In this invention, an ultra thin layer of CoCr alloy nucleation layer is sputtered at an extremely low deposition rate above a predominantly (200) oriented Cr film followed by a CoCrPt based alloy sputtered film at higher rates and moderate temperatures. This structure creates a media which has very high Hc, and excellent PW50, low noise and excellent low TNLD values. By using this technique, the CoCrPt magnetic film achieves excellent in-plane crystallographic orientation, and high Hc is achieved with minimal amount of Pt addition to the magnetic film. The method allows very fine grain structure of cobalt to be formed which contributes to good signal to noise ratio. A fine grain structure combined with chromium segregation between the grains improve the signal to noise ratio even more. A high degree of in-plane c-axis orientation is achieved in the cobalt layer which provides very high hysteresis loop squareness which helps to improve the OW and TNLD. The perfection of the grains is very high so that high anisotropy is obtained in the magnetic layer, resulting in high Hc without the necessity of addition of high level of Pt. The high degree of crystalline perfection also contributes to low TNLD.

The present invention relates generally to magnetic recording media used in rigid disc drives commonly used for computer data storage and methods of making the same.
In the hard disk drive industry, the ever-increasing recording density demands continuous improvement in hard disk recording media so as to support a higher linear recording density (thousands of flux changes per inchxe2x80x94KFCI) and track density (thousands of tracks per inchxe2x80x94KTPI). Recording density is proportional to the product of KFCI and KTPI, and is typically expressed as giga-bits per square inch (Gb/in2). Currently the recording density is increasing at compound annual growth rate of 60%.
In order for the media to be able to support the high KFCI (e.g., over 200 KFCI), the pulse width (PW50xe2x80x94pulse width at 50% of pulse amplitude) needs to be as small as possible to reduce the inter-symbol interference so that high resolution at high recording density can be obtained. The resolution is defined as the pulse amplitude at high frequency divided by the pulse amplitude at low frequency. Based on generally known magnetic recording theory, in order to reduce PW50 and hence increase resolution, the magnetic recording media must have high coercivity, Hc. For today""s typical recording density of 2 Gb/in2, the value of Hc needs to be on the order of 2500 Oe, and in future it needs to be 3000 Oe or more for even higher recording density. Other means of reducing PW50 include increasing the hysteresis loop squareness, generally defined as xe2x80x9cSxe2x80x9d which is ratio of remanent to saturation magnetization (Mr/Ms), increasing the coercivity squareness xe2x80x9cS*xe2x80x9d, increasing the remanent coercivity squareness xe2x80x9cS*remxe2x80x9d, and narrowing the switching field distribution (xe2x80x9cSFDxe2x80x9d), as described by William and Comstock in xe2x80x9cAn Analytical Model of the Write Process in Digital Magnetic Recording,xe2x80x9d A.I.P. Conference Proceedings on Magnetic Materials 5, p. 738 (1971).
For increased TPI, the media should also have high Hc to support a high off track compressibility (OTC). OTC is the measure of how much the individual tracks can be squeezed together before they start to interfere with each other and degrade the error rate as the track being squeezed. For example, in order to support 10 KTPI, the Hc of the media should be equal to or higher than 2500 Oe. In summary, in order for the media to be able to support high areal recording density, Hc of the media must be as high as possible.
Other parameters of importance for recording performance are overwrite (OW), signal to noise ratio (SNR), and total non-linear distortion (TNLD). Overwrite is a measure of the ability of the medium to accommodate overwriting of existing data. In another words, OW is a measure of what remains of a first signal after a second signal (for example of a different frequency) has been written over the original data. OW will be low or poor when a significant amount of the first signal still remains after over-writing. OW is generally affected by the coercivity, the squareness, and the SFD of the medium. For future high density recording, higher Hc media will be preferred for narrower PW50 and high resolution. However, an increase in Hc is generally accompanied by reduction in OW. Thus, there is a need in the art to improve the S* and the SFD to obtain improvements in OW for a given Hc. High hysteresis loop squareness and narrow switching field distribution can be obtained by having uniform distribution of the grain size of the media.
Another factor which is important for increased KFCI and KTPI is that the signal to noise ratio must be maximized. There are contributions to SNR from the electronics and the channel used to process the magnetic signal. But there is also intrinsic noise from the media that must be minimized. The largest contribution to the media noise is generated from the interparticle (or intercrystalline) magnetic exchange interaction. To suppress this exchange interaction, one must isolate the magnetic crystals from each other by one or more nonmagnetic elements (such as Cr atom) or compounds. The amount of separation need be only a few angstroms for there to be a significant reduction in intergranular exchange coupling. Another source of intrinsic media noise is the size or dimension of the magnetic grain. As the recording density approaches 2 Gb/in2 and beyond, the bit size along the track will be in the order of 0.1 xcexcm or less. Therefore to prevent the excessive noise arising from the physical dimensions of the grain, the diameter of each magnetic grain on the average should be approximately 0.01 xcexcm (10 nm) or less for media in the 2.0-2.5 Gb/in2 media range. The grain size should be approximately 7.5 nm or less for 5 Gb/in2 media, and should be approximately 5 nm or less for 10 Gb/in2 media. Intrinsic media noise has been theoretically modeled by J. Zhu et al. in xe2x80x9cMicromagnetic Studies of Thin Metallic Filmsxe2x80x9d in Journal of Applied Physics, Vol. 63, No. 8, (1988) p. 3248-53 which is incorporated by reference herein. T. Chen et al. also describe the source of intrinsic media noise in xe2x80x9cPhysical Origin of Limits in the Performance of Thin-Film Longitudinal Recording Mediaxe2x80x9d in IEEE Transactions on Magnetic, Vol. 24, No. 6, (1988) p. 2700-05 which is also incorporated by reference herein.
There is another intergranular interaction, called magnetostatic interaction, which acts over a much greater distance between particles as compared to the exchange interaction. Reducing the magnetostatic interaction does reduce intrinsic media noise slightly. However, the effects of magnetostatic interaction actually improve hysteresis loop squareness and narrow the switching field distribution (but to a lesser extent than the exchange interaction), and hence improve PW50 and OW. Therefore, magnetostatic interaction is generally desirable and hence tolerated.
Total non-linear distortion (TNLD) is another parameter that needs to be reduced for high density recording, and it comes about from intersymbol interference between adjacent bits, and partial erasure of a bit at the transition during writing. TNLD can be reduced by increasing the coercivity, reducing the remanent magnetization Mr, and reducing the film thickness T, for a reduction in remanence thickness product MrT. TNLD is also improved by orienting the easy magnetization direction of the magnetic particles in the plane of the media. Increasing the Hc is desirable not only for TNLD but also for PW50 as mentioned previously. Since TNLD increases as the recording density increases, it is becoming an important parameter for higher recording density.
In order to obtain the best performance from the magnetic media, each of the above criteria such as PW50, resolution, OW, SNR, and TNLD must be optimized. This is a formidable task, as each of these performance criteria are interrelated. For example, obtaining a narrower PW50 and reducing TNLD by increasing the Hc will adversely affect OW. A thinner medium also provides narrower PW50, better OW, and lower TNLD, however the SNR decreases because the media signal itself is reduced. Increasing squareness of the hysteresis loop contributes to narrower PW50, better OW, and lower TNLD, but may increase noise due to intergranular exchange coupling and magnetostatic interaction. The SNR of the media can be reduced by decreasing the grain of the media, however smaller grain size may reduce Hc due to onset of super-paramagnetic effect which comes about due to inability of the grain to support the magnetization when it competes with the thermal fluctuation. In general, the effect of onset of super-paramagnetic can be delayed by increasing the Ku of the magnetic grain through addition of platinum which has high orbital moment, and also improving the crystalline perfection of the hexagonal close packed (HCP) cobalt grains.
Therefore, an optimal thin film magnetic recording medium for high density recording applications that can support high bit density will require low noise and high signal without adversely sacrificing PW50, OW and TNLD. The cobalt alloy which is currently used for optimization of certain of the above performance criteria typically includes the addition of chromium (Cr), tantalum (Ta) and platinum (Pt), due to their ability to provide high Hc and high magnetic moment. Chromium is typically added in the amount greater than 10 atomic % to act as segregant to separate the cobalt alloy grains for noise reduction and for corrosion resistance. Other additives such as Ti, V, W, Mo are sometimes used. In all cases, the cobalt crystal structure must be hexagonal close-packed (HCP), and it is preferable to have the c-axis of the grains oriented in the film plane. This is accomplished by depositing a chromium film below the cobalt layer and arranging for the epitaxial growth of cobalt alloy grain above the chromium layer. In order to describe the crystallography of the cobalt alloy and chromium, planes and directions in the crystal are denoted by generally accepted conventions, such as described in xe2x80x9cElements of X-ray Diffractionxe2x80x9d by B. D. Cullity published by Addison-Wesley Publishing Co. Inc., herein incorporated for reference. It is typical to describe the crystallographic planes and directions in hexagonal crystals such as cobalt by a 4 indices notation called Miller-Bravais indices, while cubic structure crystals such as chromium are denoted by 3 indices notation called Miller indices. Brackets, xe2x80x9c less than   greater than xe2x80x9d are used to describe crystallographic directions, while parenthesis xe2x80x9c( )xe2x80x9d are used to denote specific planes. xe2x80x9c{ }xe2x80x9d are used to denote a class of planes which are crystallographically equivalent. For example with chromium with body-centered (BCC) crystallographic structure,  less than 001 greater than  direction is normal to a (001) plane. For a hexagonal crystal structure such as cobalt, the crystal surface with the most dense atomic packing is the (0001) plane and the direction normal to that plane is  less than 0001 greater than  direction. The  less than 0001 greater than  direction is often referred to as the c-axis as described earlier. The crystallographic directions and the surfaces for cobalt is shown in FIG. 1 and those for chromium are shown in FIG. 2.
The crystallographic orientation relationship that occurs between hexagonal cobalt film and BCC chromium film was originally reported by J. Daval and D. Randet in xe2x80x9cElectron microscopy on High-coercive-force Coxe2x80x94Cr Composite Filmsxe2x80x9d in IEEE Transaction on Magnetics, MAG-6, No. 4, (1970) p. 768-73. This work was preceded by work by J. P. Lazzari, I. Melnick and D. Randet in xe2x80x9cExperimental studies using in-contact recording on chromium-cobalt filmsxe2x80x9d in IEEE Transactions on Magnetics, Vol. MAG-5, No. 4, (1969) p. 955-59 where they reported that Hc of the cobalt film is increased by its deposition on top of a chromium underlayer.
The crystallographic orientation of chromium which promotes the cobalt c-axis to lie in the plane of the film is to arrange for chromium film to grow with  less than 001 greater than  preferred growth, which means that {001} type planes of chromium lie in the plane of the film. It has been found that cobalt {11{overscore (2)}0} type planes match well with the atoms on a {001}Cr plane as shown in FIG. 3 hereof. Lattice spacing for pure Cr (ao=2.885 xc3x85) and pure Co (c=4.069 xc3x85, ao=2.507 xc3x85) is illustrated in FIG. 3. As seen in the Figure, the  less than 0001 greater than  direction of cobalt is aligned with the  less than 110 greater than  direction of the chromium lattice in the plane of epitaxy. In this direction, the Cr and Co lattices are closely matched and the mismatch is around 0.3%. Along the orthogonal direction ( less than 01{overscore (1)}0 greater than Co), the mismatch with the Cr lattice is much larger at around 6.4%. In this orientation relationship between cobalt and chromium, the lattice match is close only in one direction. The same holds true for alloys of cobalt. It should also be pointed out that in the above orientation relationship between chromium and cobalt, there are two equally plausible configuration for the cobalt. The  less than 0001 greater than Co direction can lie along two orthogonal  less than 110 greater than Cr type directions. In fact when the chromium grains are large, two variants of cobalt grains which are oriented 90xc2x0 to each other can form on the {001} surface of the chromium grains as described in xe2x80x9cEffect of Microstructural Features on Media Noise in Longitudinal Recording Mediaxe2x80x9d by T. Nolan et al. published in Journal of Applied Physics, 73(10), May 15, (1994) p. 5566-68.
A large variety of cobalt alloys have been used with a Cr undercoat. In its current industrial form, the Cr undercoat thickness is typically between 500 to 2000 xc3x85, and it is deposited on a heated substrate. A high degree of epitaxy between the Cr and the magnetic layer is required in order to obtain high Hc and high hysteresis loop squareness. Typically, Cr grows with strong  less than 100 greater than  orientation above 200xc2x0 C. In the plane of the film, the epitaxial relationship is  less than 110 greater than Cr// less than 0001 greater than Co, and {100}Cr//{11{overscore (2)}0}Co where xe2x80x9c//xe2x80x9d denotes xe2x80x9cparallel toxe2x80x9d. Alloying elements can be added to either chromium and cobalt or to both to attempt to match the lattice better. As mentioned before however, only one direction along the crystallographic direction can be truly matched, while the other direction (orthogonal) will always be mismatched in the above epitaxial orientation.
More recently, it has been shown by K. Hono, B. Wong, and D. E. Laughlin in the article xe2x80x9cCrystallography of Co/Cr Bilayer Magnetic Thin Filmsxe2x80x9d in Journal of Applied Physics 68(9) (1990) p.4734-40 that in-plane c-axis orientation may be achieved through other crystallographic relationship between Cr and Co lattice. The following lattice plane relationships have been proposed: (002)Cr//(11{overscore (2)}0)Co, (110)Cr//(10{overscore (1)}0)Co, (110)Cr//(10{overscore (1)}0)Co, and (211)Cr//(10{overscore (1)}0)Co. Generally, the addition of alloying elements into cobalt expands the lattice. For an alloy composition of CoCr10Pt18 for example, the lattice parameters are calculated to be co=4.148 xc3x85, ao=2.556 xc3x85. For this composition, the lattice mismatch for pure Cr and CoCr10Pt18 alloy for several combination of planes are listed in Table 1. The two mismatch numbers are two orthogonal directions in the plane of the epitaxy. It can be seen from table 1 that best epitaxial match can be obtained between (110)Cr and (10{overscore (1)}1)Co for a lattice mismatch of 0.2% and 2% respectively. However, in this case the c-axis of the cobalt is tilted 28xc2x0 out of the plane. Another closely matched relationship is (211)Cr and (10{overscore (1)}0)Co for a lattice mismatch of 1.7% and 2% respectively. For other epitaxial relationships where the c-axis lies in the plane of the film, the difference in mismatch along the two directions is always greater.
Since the original work by J. Daval and D. Randet on Co/Cr epitaxial film structure, there are many examples of work on both the cobalt and chromium underlayer alloys to improve the recording performance of the cobalt/chromium alloy structure. A variety of schemes have been proposed to improve the lattice matching between Cr or Cr alloys with the cobalt alloy, and hence improve the in-plane orientation of the cobalt, and improve Hc and other properties as previously noted. There are several approaches. The first involves alloy or deposition variations on a basic two layer structure, involving Cr and Co alloy films. The second approach involves use of multiple layers in the undercoat or a different material other than Cr or alloys of Cr in an attempt to affect the magnetic properties. Thirdly, multiple magnetic layers can be used to attempt a better in-plane orientation.
For a basic two layer approach, in an article by Deng et al. entitled xe2x80x9cMagnetic Properties and Crystal Texture of Co Alloy Thin Films Prepared on Double Bias Cr,xe2x80x9d Journal of Applied Physics 73(10) May 15 (1993) p. 6677-79, the authors claim that (200)Cr orientation can be formed on single crystal Si substrates which then allow (11{overscore (2)}0)Co orientation to form on the (200)Cr at room temperature. This is useful in terms of obtaining the good in-plane orientation of the Co, but the Si substrate is considerably expensive compared to conventional NiP/Aluminum substrates or alternative substrates such as glass or glass-ceramic, and therefore it is not practical. The authors also note that with substrate bias, Cr forms a strong (110) orientation, which then causes the cobalt alloy film to form with (10{overscore (1)}1)Co texture which is out of the plane and hence the Hc of the film dropped. Therefore the cobalt alloy film has a natural tendency to form with the out of plane (10{overscore (1)}1)Co orientation on (110)Cr. The Cr thickness was 1000 xc3x85 and Hc wasxe2x89xa62000 Oe for a CoCrTa film thickness of 300 xc3x85. In another paper entitled xe2x80x9cPreferred Orientation in Cr-and Co-Based Thin Films and its Effect on the Read/Write Performance of the Mediaxe2x80x9d by H-C Tsai et al. in Journal of Applied Physics 71(7), Apr. 1 (1992) p. 3579-85, the authors discuss the importance of achieving (200)Cr which then promotes the in-plane orientation of (11{overscore (2)}0)Co for higher Hc and improved parametric performance. On glass ceramic substrates (canasite) however, the authors note that (110)Cr is formed which then causes the Co-alloy to grow with the c-axis out of the plane. In fact a vertical orientation in which the c-axis is normal to the film plane was reported in one case. The authors report that formation of preferred orientation in the Cr layer is determined by substrate material and the oxygen content in the sputtered film. For the in-plane media, a Hc of 1350 Oe was obtained for CoCrTa alloy, and 1370-1830 Oe was obtained for CoCrPtTa alloy. Typical Cr thickness in these films were xcx9c1700 xc3x85, and MrT of the media was also high at around 5 memu/cm2.
Using the second approach, in U.S. Pat. No. 4,652,499 by K. Howard, it is disclosed that to improve the lattice matching between the Co-alloy and the Cr underlayer for better epitaxy, the Cr underlayer is alloyed with Vanadium (V). Other alloying additions such as Ti, Mo, Hf and Ta have been also tried. According to each of these methods, the Cr underlayer must be several hundred angstroms thick to establish the proper Cr texture for epitaxial growth of the Co-alloy. However, the consequence of forming such a thick Cr or Cr alloy layer is that the grain size of the Cr or Cr alloy also grows, to a size of several hundreds or possibly thousands of angstroms in diameter. Since the grain size of the Co-alloy deposited on the Cr underlayer will match the grain size of the Cr underlayer, the resulting epitaxially grown Co-alloy will also have a grain size of several hundreds to possibly thousands of angstroms in diameter. In such a case, the high intrinsic media noise at the magnetic transitions due to the large grains renders the media useless for current and future high density recording.
In an approach using multiple underlayer and different materials, Lee et al. (Carnegie Mellon) in xe2x80x9cNiAl Underlayers for CoCrTa Magnetic Thin Films,xe2x80x9d IEEE Transactions on Magnetics, vol. 30, no. 6, pp. 3951-3 (November 1994); xe2x80x9cEffects of Cr Intermediate Layers on CoCrPt Thin Film Media on NiAl Underlayers,xe2x80x9d IEEE Transactions on Magnetics, vol. 31, no. 6, pp. 2728-30 (November 1995); and European Patent Application Publication EP 0 704 839 A1, claiming priority from a U.S. patent application Ser. No. 08/315,096, filed Sep. 29, 1994, teach a Co based magnetic alloy layer formed above an underlayer having a B-2 crystal structure. The B-2 crystal is a body centered cubic structure alloy such as NiAl. In one embodiment, the Co based magnetic alloy layer is grown epitaxially on the B-2 structure layers directly below. The proposed rationale is that (110)NiAl and (112)NiAl preferred growth orientation of the NiAl layer provides the basis for the Co-alloy to assume a (10{overscore (1)}0)Co orientation, resulting in an in-plane c-axis orientation of the cobalt alloy, and hence resulting in high Hc.
In another embodiment, an extremely thin Cr intermediate layer (25 to 50 xc3x85) is deposited between a B-2 NiAl underlayer and the Co based magnetic alloy layer, in order to increase Hc of the CoCrPt alloy. In this case, the Cr layer is grown epitaxially on the B-2 crystal underlayer, and the Co based magnetic alloy is grown epitaxially on the thin Cr layer. While the Cr layer is necessary for increased coercivity and squareness, the Cr layer cannot interrupt the crystallographic relationship between the (112)NiAl and the (10{overscore (1)}0)Co (i.e., the indirect epitaxy between the B2 layer and the magnetic recording material layer). Thus, Lee et al. require that the intermediate layer be extremely thin (between 25 xc3x85 and 50 xc3x85) to prevent the Cr from developing its own preferred orientation. Lee et al. also state that a Cr intermediate layer is required to prevent contamination of the Co by the excess Al on the NiAl film surface, and that the Cr intermediate layer must be sufficiently thin to (a) minimize diffusion of Cr into the Co film layer, and (b) avoid interference with the epitaxy between the Co alloy magnetic recording layer and the NiAl underlayer. In their examples, relatively high coercivity up to 3300 Oe and squareness (S*) of  greater than 90% are reported for the high Pt content of 18 atomic % alloy.
Despite the high coercivity, high squareness, and fine grain structure taught by Lee et al. (see EPO 704 839 A1), the mere addition of the NiAl underlayer provides only a minimal improvement in the media noise performance, and thus the resulting media is inadequate for current and future high density recording applications. With reference to EPO 704 839 A1, this minimal improvement can be seen in FIGS. 14 and 15 showing carrier noise measurement data, and FIGS. 16 and 17 showing integrated media noise measurement data. Importantly, it appears that the media taught by Lee et al. suffers from high intergranular exchange interaction as evidenced by the high hysteresis loop squareness S* of larger than 90% shown in the above-referenced paper in IEEE Transactions on Magnetics, V.31, p. 2728, (1995). There is no teaching by Lee et al. to address the issue of reducing the noise. In addition, a very thick layer of NiAl of over 1000 xc3x85 is required in order to form the necessary (112)NiAl texture. Such thick layer is expensive to manufacture. Thick layers cause the deposition shields around the cathodes to flake early, necessitating frequent shut-downs for clean-up. Flaking parts also cause defects which is detrimental to the performance of the media. NiAl is also a difficult material to make the sputtering target out of, hence it is expensive to make. Also the use of thick layers necessitates the use of high rate sputtering methods such as using DC magnetron sputtering. A high rate can be used to deposit thick films but the machine must be cleaned frequently since the inside of the deposition chamber becomes coated just as fast as the substrates. If slower deposition method such as RF sputtering is used, the time allowed for each sample must be increased hence the throughput of the machine will be decreased. In either case, the cost of depositing a thick layer makes it impractical and costly for commercial use.
There are several other problems with the NiAl underlayer concept. As it was shown previously in Table 1, a (110)NiAl texture is like the (110)Cr in that it is also likely to cause the growth of (10{overscore (1)}1)Co texture, since the lattice match is equally favorable. Since (10{overscore (1)}1)Co texture has c-axis oriented 28xc2x0 out of the plane, it is not a favorable orientation for good parametric performance. Therefore it is quite possible that under some more varied deposition or substrate conditions that can occur in a typical manufacturing environment, the perfect in-plane orientation of the cobalt alloy layer may not occur. We also believe that the high coercivity taught by Lee et al. results from the use of a relatively large amount of platinum (e.g., xcx9c18 atomic per cent to obtain Hc of 3300 Oe), as opposed to being derived exclusively from the c-axis in-plane orientation of the cobalt and perfection of the crystallite lattice. As will be discussed further below, a properly isolated CoPt based film can achieve a coercivity of over 3,000 Oe, even with less than 13 atomic % Pt in the alloy even without the benefit of Cr epitaxy, (that is without c-axis in the plane of the film) if the grains in the film are properly isolated as we have shown in the copending patent application by Chen et al., Ser. No. 08/802646, which application is assigned to the assignee of the present invention, and which application is hereby incorporated by reference herein. Indeed, such a high coercivity may be produced with random orientation of grains. The fact that an Hc even higher than 3300 Oe was not obtained by Lee et al. with 18 atomic % Pt in the alloy together with the fact that they obtained extremely high hysteresis loop squareness and no improvement in noise performance indicate that the film taught by Lee et al. has significant intergranular exchange interaction between the physical grains.
The third approach to improving in-plane orientation of the cobalt alloy film is the dual magnetic layer approach as taught in many publications as cited below. In a laid-open Japanese patent application JP8-147660 by Yan and Okumura, a double layer of CoCrTa/CoCrPt on Cr has improved recording density and lowered noise. In one example, the total magnetic layer thickness is 200 xc3x85 with thin CoCrPt top layer thickness between 20-60 xc3x85. Cr thickness was 700 xc3x85, and Pt concentration in CoCrPt alloy was between 10-15 atomic %. With CoCrTa:CoCrPt ratio of 150 xc3x85:50 xc3x85(i.e. 3:1), a maximum Hc of 2150 Oe was achieved.
In another laid-open Japanese patent application JP5-120663 by Yamaguchi and Onodera (Fuji Electric), a dual magnetic layer consisting of a CoCrTa first layer and a CoCrPt second layer having low noise and high Hc is described. In this case, the thickness ratio of CoCrTa:CoCrPt between 1:9 to 7:3 is specified, with optimum around 3:7 to 5:5 (half) achieving the combination of high Hc with low noise. For a total thickness of the film at 500xc3x85, the CoCrTa layer is from 50 xc3x85(1/9) to 250 xc3x85(5/5). The maximum Hc obtained was 1900 Oe with a top layer alloy composition of Co82Cr14Pt4 with a 1000 xc3x85 Cr underlayer. The MrT of the media was xcx9c3.6 memu/cm2. The inventors also stipulates that in the preferred embodiment, the CoCrTa film must be sputtered within 15 seconds after the Cr layer is deposited, and CoCrPt is to be sputtered within 10 seconds after the deposition of CoCrTa film. This is to maintain the high Hc of the film and prevent contamination of the film once it has been sputtered.
In a Japanese laid-open publication JP5-109043 by Inao, Utsumi and Kondoh, the order of the magnetic alloy film stack is now reversed, where the first layer above the Cr is CoCrPt followed by CoCrTa alloy. The first layer is 100 to 1000 xc3x85 thick with preferred thickness of 100 to 800 xc3x85. For the second layer, the thickness is 100 to 1000 xc3x85 with a preferred layer thickness of 150 to 700 xc3x85. They claim that it is preferable to have CoCrPt as the bottom layer with its high Hc capability and the low noise CoCrTa film on top for the best performance. In their preferred embodiment, they obtain maximum Hc of about 1700 Oe with 10 atomic % Pt for Cr(3000 xc3x85)/CoPt10 (300 xc3x85)/CoCr12Ta4 (400 xc3x85) structure. The Hc they achieve is actually very low for the Pt content that they use, indicating that less than ideal Ku has been achieved in their media. No mention is made of the orientation of the magnetic media.
In an article titled xe2x80x9cRecording Characteristics of CoCrTa, CoCrPt Double Layerxe2x80x9d by Yamaguchi et al. in 15th Annual Japanese Applied Magnetic Conference (1991), the authors also describe a magnetic double layer consisting of 150 xc3x85 thick CoCrTa alloy as the first layer above the Cr, followed by 350 xc3x85 thick CoCrPt layer as having good resolution, SNR and OW. Films are sputtered by DC magnetron method to achieve Hc of 1200-1900 Oe. Alloy compositions are not specified. In an accompanying article by Kodama et al. in the same journal entitled xe2x80x9cMagnetic properties of CoCrTa, CoCrPt Double Layersxe2x80x9d, the authors show that for 500 xc3x85 total film thickness, there is a smooth transition in Hc from the lower value of 1000 Oe for 100% CoCrTa to higher Hc value of about 2100 Oe for 100% CoCrPt as the ratio of thickness of the two alloy films are changed. Yamaguchi et al. show that for CoCrTa=150 xc3x85 and CoCrPt=350 xc3x85, superior SNR, OW and PW50 are obtained over those of a single layer CoCrPt film.
More recently, a paper by P.Glijer et al. (Univ. of Minnesota) entitled xe2x80x9cAdvanced Multilayer Thin Films for Ultra-High Density Magnetic Recording Mediaxe2x80x9d published in IEEE Transaction on Magnetics, Vol. 30, No 6, (1994), describe the properties of CoCrTa/CoCrPt double layer with the thickness ratio of 50 xc3x85:200 xc3x85. It is claimed that CoCr16Ta2.5 alloy has better lattice match with a Cr underlayer than with CoCr13Pt13 hence leading to better in-plane c-axis orientation of the cobalt alloy magnetic layer. The epitaxial relationship was quoted to be {10{overscore (1)}0}Co matched to {110}Cr and {112}Cr. A Very high Hc of 3720 Oe was obtained for MrT of 0.9 memu/cm2, with a good S* ratio of 0.88. Media noise was expected to be higher for this structure however, due to increased intergranular exchange present in the media.
A paper by L. L. Fang et al. entitled xe2x80x9cNew High Coercivity Cobalt Alloy Thin Film Medium Structure for Longitudinal Recordingxe2x80x9d published in Applied Physics Letters, 65 (24) Dec. 12, (1994) also describes a double layer magnetic structure using CoCr13Ta3 and CoCr10Pt18. In this work, the Cr layer is 1000 xc3x85 and a range of thickness rations of CoCrTa and CoCrPt is explored. For a total double layer thickness of 300 or 400 xc3x85, the Hc peaks at around 4000 Oe for 50 to 60 xc3x85 thick intermediate CoCrTa layer. The orientation relationship is reported as (110)Cr matched to (10{overscore (1)}1)Co. Even though this implies out of plane c-axis orientation of the cobalt alloy, the hysteresis loop squareness is very high. Whereas without the CoCrTa intermediate layer, the magnetic layer shows vertical orientation, as indicated by x-ray diffraction and hysteresis loop. The high Hc obtained by Fang et al. is quite likely due to the high Pt content in the magnetic layer, and the fact that high squareness was obtained despite the out of plane c-axis orientation suggests that media has high exchange coupling.
A paper by B. Zhang et al. entitled xe2x80x9cCoCrTa/CoCrPtTa Double-Layer Films for Magnetic Recordingxe2x80x9d published in IEEE Transactions on Magnetics Vol. 32 No. 5 p. 3590 (1996) also describes recording and magnetic properties of various combinations of double layer structures. In this work, the ratio between CoCrTa and CoCrPtTa layers are varied as in Glijer""s work. When the bottom CoCrTa layer is 1/3 of the total thickness and balance of 2/3 made up of CoCrPtTa, the Hc peaks at around 2500 Oe which is higher than the Hc of each alloy by itself. SNR however decreased monotonically with increasing CoCrPtTa thickness. The hysteresis loop of the double layer film shows a more square loop compared to the single layer films. When the film stacking order was reversed with CoCrPtTa as the bottom layer however, the results were completely different. The SNR remained low for the most part, inheriting the poor SNR of the CoCrPtTa layer, while Hc increased monotonically with CoCrPtTa thickness and never peaking as it did in the reverse stacking. It is claimed that the CoCrTa alloy has the right grain structure, namely smaller and more uniform grain size which can be passed on to CoCrPtTa when it is deposited first above the Cr underlayer. From their results, a thickness in the range of xcx9c60 xc3x85 is required in order to set the proper microstructure of CoCrTa in place for the subsequent proper growth of CoCrPtTa layer. They do not state the orientation relationship in their film, but they show x-ray diffraction data showing a strong presence of (110)Cr along with (10{overscore (1)}1)Co and (10{overscore (1)}0)Co orientations. Alloy compositions are not stated, nor are the deposition conditions in this publication.
Lastly, in an published abstract #CC-09 by J. Zou et al. (Carnegie Mellon) for the Joint MMM-Intermag Conference to be held January, 1998, the authors claim that by interspersing CoCrTa between the (112)NiAl plane and CoCrPt magnetic layer, the (10{overscore (1)}0)Co texture improves and in-plane Hc also increases. (10{overscore (1)}0)Co in CoCrTa is claimed to have better lattice match to the (112)NiAl than CoCrPt. Therefore interspersing a very thin layer of CoCrTa is claimed to cause better in-plane orientation of the CoCrPt film, hence contributing to the high Hc and hysteresis loop squareness.
In all of the aforementioned publications, a common theme is that lattice matching between Co alloy and Cr is claimed as the key contributor to the high Hc and lower noise. Particularly with respect to double layers using CoCrTa first layer and CoCrPt second layer, it is claimed that CoCrTa is better lattice matched to Cr, whether the orientation relationship claimed is (200)Cr//(11{overscore (2)}0)Co, (110)Cr//(10{overscore (1)}0)Co or sometimes even (110)Cr//(10{overscore (1)}1)Co. However, as shown earlier in table 1, a perfect lattice match in all directions is not possible. Furthermore, perfect or even good epitaxy in an actual production machines is also difficult to achieve. One reason is that residual gases in the system which are often water vapor and oxygen which can be produced from the water vapor, can affect the interface between the Cr and the Co alloy layer and cause loss or partial loss of epitaxy.
From our experience in this work, most of the deposition processes reported in the references cited in this application can be considered xe2x80x9chigh-ratexe2x80x9d. Typically rates above approximately 5 xc3x85/sec fall in the high rate category. Although some of the prior art discloses lower deposition rates, such processes are typically used only in research settings, where there is little or no emphasis on throughput. In contrast, it is generally considered desirable to use high rate processes to achieve high throughput in a production environment to make the process commercially viable. For example, in many production level machines, rates as high as 50 xc3x85/sec are typically used in order to maintain high throughput.
One alternative to reducing the effect of residual gases on epitaxy is to improve the vacuum of the deposition chamber. M. Takahashi et al. in xe2x80x9cThe Ultra Clean Sputtering Process and High Density Magnetic Recording Mediaxe2x80x9d published in IEEE Transactions on Magnetics Vol. 33, No. 5 p. 2938 (1997) shows that by maintaining the vacuum at an ultra high vacuum level of about 10xe2x88x929 Torr, higher Hc is obtained at a thinner Cr thickness. It is claimed that high Hc is obtained through increase in the magnetocrystalline anisotropy field Hkgrain, and by a decrease in the degree of intergranular magnetic coupling. The high vacuum allows better segregation of Cr at the grain boundary, and formation of smaller magnetic grains through smaller Cr underlayer grains. These effects also in turn improved the S/N ratio of the media. It can also be inferred that in-plane orientation of the media is improved by reducing the oxidation of Cr underlayer. Although the results are impressive, the type of vacuum levels which are advocated are not practical in terms of a low cost, high throughput manufacturing operation.
Therefore, under deposition conditions that are not entirely perfect in terms of vacuum conditions and at high rate of deposition typically used in a commercial application, obtaining good epitaxy between Cr and Co-alloy layer is difficult to achieve. Hence c-axis in-plane orientation of the hexagonal cobalt film is not necessarily achieved, leading to lower Hc than is possible for a given Pt content of CoCrPt based alloy, and also reduced squareness. In addition, the grain size may not be uniform and grain themselves may not have the proper crystalline perfection for high anisotropy constant Ku. These factors lead to films having less than desirable parametric performance. As it was shown earlier, even under best conditions where epitaxy is favored, there is still inherent mismatch between hexagonal cobalt and cubic chrome lattice. Lack of good epitaxy and subsequent poor growth-of the magnetic layer can result in formation of a large amount of imperfections such as dislocations, stacking faults and other irregularities in the crystalline structure which will reduce Hc potential for given alloy composition and Pt content. If the magnetic crystallites contain a high amount of imperfections, the Ku of the media will be decreased drastically. When the CoCrTa layer is inserted between the CoCrPt based alloy and Cr according to the above cited prior art, it apparently helps the perfection of the CoCrPt based alloy to some extent, but the cited literature still has to resort to high Pt containing alloy to raise the Hc. High platinum costs more, reduces the magnetization Ms of the film and hence requires a thicker film to obtain a given MrT, and also causes more lattice imperfections in the cobalt HCP structure. At above 8% platinum content, there is increased chance of producing FCC (face-centered cubic) crystal structure which will reduce the Ku value of the HCP structure by more than an order of magnitude. Hence adding an excessive amount of Pt in an attempt to raise Hc will defeat the purpose of the benefit of Pt. Because of these difficulties, we have through careful research invented a new and unique method of overcoming the aforementioned difficulties as follows:
In this invention, a thin layer of a Co alloy such as a CoCr based alloy, including an alloy having the same composition used for the main magnetic layer, is sputtered at an extremely low deposition rate of preferably  less than 1.0 xc3x85/second to a thickness of preferably less than 20 xc3x85 on a {200} oriented Cr film under moderate substrate temperatures, followed by high rate deposition of CoCrPt based alloy to create a media which has very high Hc, low PW50, high SNR and low TNLD values. By using this technique, the CoCrPt based alloy layer achieves excellent in-plane crystallographic orientation, and high Hc is achieved with a minimal amount of Pt. The combination of low Pt, high rate deposition of the main magnetic layer and relative insensitivity of the process to the vacuum conditions of the system makes the method very commercially viable. There are also several additional key benefit which the previous literature have failed to achieve. They are as follows: First, the method allows very fine grain structure of cobalt to be formed which contributes to good signal to noise ratio. Second, the fine grain structure combined with chromium segregation between the grains improve the signal to noise ratio even higher. Third, a high degree of in-plane c-axis orientation is achieved in the cobalt layer which provides very high squareness media which in turn helps to improve OW and obtain low TNLD. Fourth, the quality of the grains is high so that high anisotropy constant Ku, is obtained in the magnetic layer, resulting in high Hc without the necessity of addition of excessively high level of Pt. Low TNLD also results from the high perfection of the grains. These results are obtained using very conventional sputtering processes, without having to invoke ultra high vacuum conditions.
Also there is apparently little impact of specific % lattice mismatch between the Cr underlayer and the CoCrPt based alloy in order to obtain high Hc and good recording performance as long as there is a (200)Cr orientation in the Cr to allow some matching with the subsequently deposited cobalt alloy film. Similar results can be obtained for different Cr alloy layers, such as CrV films. There is much more flexibility now to choose the alloy composition based on the ability of the alloy to affect such parameters as ability to segregate, or to form small grain sizes as opposed to adjusting the magnetic and underlayer compositions to adjust for lattice matching between the two as proposed conventionally.
The present invention consists of magnetic thin film media with the structure of chromium or chromium alloy underlayer, followed by an ultra-thin nucleation layer consisting of CoCr based alloy deposited at slow deposition rate with sufficient atomic mobility conditions, such as with substrate heating or in combination with DC bias on the substrate, followed by full deposition of CoCrPt based magnetic alloy at high deposition rate which is the primary layer for the recording. First, a Cr or Cr alloy film is sputtered using preferably RF diode or RF magnetron cathodes, with heating up to around 250xc2x0 C. or lower at a base pressure of 1xc3x9710xe2x88x926 Torr or better. A conventional deposition rate of between 5 to 50 xc3x85/sec is first used to deposit Cr layer to obtain preferably a (200)Cr orientation. The Cr thickness is typically 300 xc3x85 or less. The second layer which is a nucleation layer consisting of preferably a CoCr based alloy such as CoCrTa is deposited at a very low deposition rate, and it is designed to form a small-grained template for the subsequent growth of the CoCrPt based alloy magnetic layer. An important discovery is that the nucleation layer is very thin, at preferably less than approximately 20 xc3x85 thick, and that it should preferably be deposited at a very slow rate of less than approximately 1.0 xc3x85/sec. In addition, sufficient mobility is preferably imparted to the slowly depositing atoms. This can be achieved by various means including applying substrate heating, substrate DC bias, and using an RF sputter deposition process. The RF process allows for low sputter rate and also induces high mobility to the sputter species from the high bombardment of substrate with electrons.
Alternatively, instead of RF diode sputtering, DC magnetron sputtering can be used, particularly in the high rate deposition of Cr underlayer and the top magnetic layer. For the nucleation layer, DC magnetron can be used for low rate deposition, but it will be more difficult to obtain low rates compared to the RF deposition method. If DC magnetron sputtering is used, additional means of providing high mobility to the sputtering species are desirable, such as a higher level of substrate heating and/or higher DC substrate bias.
By forming the ultra-thin CoCr based alloy nucleation layer by the above method, the magnetic properties of CoCrPt based alloy film such as CoCrTaPt sputtered at high deposition rate above the nucleation changes drastically over the case where the nucleation layer does not exist. The Hc is dramatically raised and hysteresis loop squareness increases. This media will typically exhibit coercivity squareness and remanent coercivity squareness of 0.8 or better and a switching field distribution approaching 0.2 or less. At the same time, the intrinsic media noise is reduced substantially, and resolution is enhanced. TNLD and OW values are also improved over the performance of a non-epitaxial three-dimensional isotropic film. The media is ideally suited for current and future high storage density applications, such as use with magneto-resistive (MR) heads and future giant MR head.
An important aspect of our invention is to overcome the imperfect lattice matching between Cr or Cr alloy underlayer and the magnetic layer by introducing a very good lattice matching of a nucleation layer to the magnetic layer. At low deposition rates with high enough atomic mobility of the nucleation layer, a near equilibrium growth condition is obtained so that a near perfect HCP crystal structure of the nucleation layer is obtained. The thin nucleation layer then serves as a template for the high rate deposition of magnetic layer. Since the main magnetic layer has the same crystal structure as, and is very closely lattice matched to the nucleation layer, there is a high likelihood of good epitaxy between these two layers, hence leading to in-plane orientation of the c-axis and more perfect crystal lattice structure of the cobalt alloy grains. Achieving an equilibrium or near equilibrium condition during the initial growth of the nucleation layer on the Cr or Cr alloy underlayer appears to be very critical to achieving good epitaxy between the nucleation layer and the Cr underlayer. The Cr or Cr alloy underlayer has cubic BCC structure on which the hexagonal HCP structure of the cobalt alloy film must grow. The two lattices do not match very well, and near equilibrium conditions with high mobility of the depositing species will favor better epitaxy. The surface of the Cr or Cr alloy film is also very sensitive to vacuum. It can be easily contaminated or oxidized so that even if proper crystallographic orientation of the Cr layer has been deposited, the subsequent magnetic layer may not grow epitaxially above it. In fact, the cobalt alloy film generally does not favor growth with the c-axis in the plane of the film. The (0002)Co growth (perpendicular orientation) is much more favored, especially at a high deposition rate, so that any problem in epitaxy between a depositing Co alloy film and a Cr underlayer will cause perpendicular orientation to form. Near-equilibrium, slow-rate deposition overcomes this tendency for perpendicular orientation in the cobalt alloy film, and also allows time for the depositing atoms to xe2x80x9cfindxe2x80x9d the correct epitaxy for in-plane c-axis orientation. Near equilibrium growth state can also expel the impurity atoms such as oxygen and other residual gas from the surface.
Once a CoCr based alloy nucleation layer is formed, the surface is more favorable for subsequent deposition of the magnetic layer, even at moderate vacuum conditions so that subsequent to its deposition, the magnetic layer film can be deposited at a higher rate and achieve good in-plane orientation as long as it has close lattice matching with the nucleation layer. It was discovered that this can occur even when the nucleation layer film thickness is only few angstroms thick. Therefore the process is well-suited for use in production equipment where the vacuum levels are usually poorer compared to machines typically used in research. In using a typical production deposition tool for making the recording media, a high rate deposition is necessary in order to make the process economical. But in so doing, thermodynamic equilibrium is difficult to achieve and good epitaxy is often compromised. By splitting the magnetic layer process into two parts, namely a thin and slow deposition rate layer and thicker high rate deposition layer, high throughput is still maintained. Therefore the structure and the method of deposition of the layers are well-suited for production deposition process.
In previous art using much thicker films of CoCrTa as an intermediate layer between Cr and CoCrPt, it is claimed that better lattice match between Cr and CoCrTa alloy as opposed to Cr with CoCrPt is the key contributor to obtaining high Hc and in-plane c-axis orientation. In this invention, there is no limitation to CoCrTa as the alloy of choice for nucleation layer. Since it is the slow deposition rate with high mobility which determines the quality of the epitaxy between the Cr underlayer and the nucleation layer, there is more freedom in the alloy selection for the nucleation layer. In fact, the most ideal choice would be that the same alloy composition is used for both the nucleation layer as well as for the magnetic layer. In practice, a small modification from the magnetic alloy can be used for the nucleation layer composition. For example, for a CoCr15Ta4Pt3 magnetic layer, CoCr15Ta4 without the Pt can be used as the nucleation layer to save the cost of the Pt, but the lattice constant of the two alloys are very close to each other (e.g., within 0.5% lattice mismatch). For higher Pt content magnetic alloy, the nucleation layer may require additional Pt so as to maintain a lattice constant that is closer to that of the magnetic layer. It is quite important that there is a close lattice match between the nucleation layer and the magnetic layer in this invention in order to obtain good epitaxy and also to obtain a high quality crystalline film in the magnetic layer for high Ku values. However, since the crystal structure will be the same hexagonal structure between the nucleation layer and magnetic layer, there is actually more flexibility in the choice of alloys for the two layers. Therefore the alloy selection can be based more on factors such as ability to form small and uniform grains or on basis of creating segregated grains as opposed to selection based on lattice matching considerations alone as is the case with previous art. See the earlier referenced patent application of Chen et al., Ser. No. 08/802,646, for a description of some methods of achieving small and uniform grains and for creating segregated grains.
Control of grain growth and structure is also a key benefit of the present invention. Media according to the present invention comprise a magnetic recording layer having fine individual magnetic grains having a diameter of 100 xc3x85 or less which are isolated from one another by a solid segregant such as excess Cr in CoCrPt base alloy. The magnetic grains have a uniform size, and spacing on the order of about 10 xc3x85. Importantly, the grains of the magnetic recording layer are principally single crystals with minimum defects in the grains, such as dislocations and stacking faults throughout the thickness of the layer, so as to maximize the magnetocrystalline anisotropy constant, Ku, of each individual grain, and furthermore, the c-axis of the grains are oriented predominantly in the plane of the film and are randomly oriented in the plane to provide high Hc. Such magnetic grain structure is a consequence of the use of thin nucleation layer formed in slow rate deposition under near equilibrium condition and high atomic mobility. Since the main magnetic layer grains grows epitaxially over the nucleation layer grains, controlling the size of each nucleation site (grains) and the spacing between adjacent nucleation sites will provide an easy means for controlling the grain growth characteristics, size and spacing of the magnetic recording layer, as well as providing large angle grain boundaries. In addition, proper control of the size and spacing of the nucleation layer grains provides a method for optimizing the segregation of segregant material such as Cr at the grain boundaries in the magnetic recording layer.
The consequence of having the microstructure as described above on the magnetic properties of the media are as follows. Smaller grains contribute to lower intrinsic noise in the recording media. More crystalline perfection in the grains provide the highest possible Ku so that high Hc is obtained for a given Pt concentration in the alloy. Uniform and small grains also contribute to improving the OW. TNLD is improved by having the c-axis in the plane of the film. High hysteresis loop squareness is obtained with having uniformly isolated grains, with uniform size distribution.
Lastly, the process used herein is highly economical and reproducible. With even a relatively low platinum content of around 3 atomic %, an Hc value of about 3000 Oe has been obtained at the MrT value of 0.7-0.8 memu/cm2. This is in contrast with the very high Pt content used by others to obtain high Hc in the literature we have cited. Reducing the Pt content in the sputtering target will reduce the cost of producing the disk significantly, and increase the Ms of the film. This means that film thickness itself can be reduced for a given MrT product, which results in better performance through effectively lower head-media spacing.

Ultra-thin nucleation layer for magnetic thin film media and the method for manufacturing the same


The invention is a dial inbound MIU which includes a rechargeable power supply, such as a double layer capacitor (sometimes called a "supercapacitor" or a "SuperCap") or a rechargeable battery. The power supply can be recharged from the telephone line, either from the DC current available when the phone line is on-hook or off-hook or from the AC current which is available when the telephone line is ringing.

The present invention relates to an apparatus for calling a central computer and transmitting metering information over the telephone lines. In particular the present invention relates to a dial inbound Meter Interface Unit ("MIU") which derives its power from the telephone line, particularly from a ringing telephone line, to which the MIU is connected.
As used herein, the term Meter Interface Unit ("MIU") refers to an electronic unit located at the residence or business location of a customer of a public utility (water, gas, electricity, or heat). While the term "MIU" is generally used to refer to devices which interface a utility meter with a medium such as telephone or radio ("RF"), as used herein, the term "MIU" will be limited to telephone MIUs, particularly telephone MIUs which are used for dial inbound purposes.
A dial inbound MIU is one which calls a central computer system located at an office of the public utility. The central computer is typically equipped with a number of modems and telephone lines for placing and receiving telephone calls to and from remote MIUs which are located at customers' locations. A dial inbound MIU is an MIU which is used to call the central computer from a customer's location.
Heretofore, dial inbound MIUs have been used to dial central computers for the purpose of transmitting utility metering data from the customers' meters to the utility. The MIU dials the central computer periodically or at a time which has been predetermined and entered into the MIU, either directly (typically at the time the MIU is first installed at a customer's location) or downloaded to the MIU by the central computer (when the MIU dials the central computer to upload metering information). In a typical transaction, an MIU reads metering information from a meter, dials the central computer, and uploads the metering data via modem to the central computer. While the MIU is connected to the central computer, the central computer may download certain information to the MIU, such as the time at which the MIU should next send meter data to the central computer. Thus, one feature of the MIU is that it must have knowledge of its next call back time. In order to retain this information, the MIU typically has a semiconductor device called a real time clock which retains either the real time, typically expressed as month, day, year and hour, minute, second, or, alternatively, a countdown of days, hours, minutes, and seconds (although possibly expressed as only hours, minutes, seconds, or even only as seconds) to the next call.
In a typical installation at a customer's residence, there may be only a single telephone line which serves the residence. Accordingly, there must be provisions within the MIU to enable the MIU to detect whether the telephone line is in use, so that the MIU can determine whether it can make use of (seize) the telephone line. In addition, after the MIU has seized the telephone line, it must be able to detect whether an extension to the seized telephone line has been lifted off-hook by someone at the location, in which event the MIU must release the telephone line to the other user.
In view of the electronic circuitry within an MIU and the typical desire to prevent power outages from causing the circuitry to lose information, such as the current time or call-back time, both of which require the real time clock circuit, it is desirable for an MIU to be able to be operated independently of the AC power at the customer's location. Thus, it has heretofore been typical for dial inbound MIUs to be operated by either internal or external batteries.
U.S. Pat. Nos. 4,455,453; 4,469,917; 4,847,892; and 4,578,534 all disclose dial inbound MIUs which are powered by external batteries. The use of an external battery renders an MIU more costly to maintain than an internal battery. In addition, external battery supplies can interfere with the installation of MIUs in confined spaces, such as pits or service boxes.
U.S. Pat. No. 4,644,103 discloses an MIU which derives its operating current from a telephone line. As described in that patent, telephone line current is used to energize a tone detection circuit in the MIU. The tone detection circuit is responsible for determining if the MIU is being interrogated by the central computer. The tone detection circuit operates intermittently. Power is used every few seconds to ensure that the circuit is functioning properly. The short powered discharge intervals associated with the device limit its capability solely to signal detection. In addition, the telephone must be frequently placed in the off-hook state to accommodate recharging of a voltage regulating capacitor. Such constant recharging of the capacitor increases the likelihood that there will be interference with the customer's use of the telephone line.
A legal limitation on the use of the telephone line as a source for powering an MIU is found in the Code of Federal Regulations, 47 C.F.R. .sctn.68.312, which limits the amount of current which can be drawn from a telephone line while the telephone is in the "on-hook" state. In the on-hook state, the telephone handset is placed on the telephone receiver, where it depresses a switch which disconnects the telephone instrument from the telephone line, resulting in an open circuit. When a telephone instrument is in the on-hook state, it is commonly referred to as being "hung up". While in the on-hook state, a device connected to the telephone line must have an effective DC resistance between the pair of telephone wires (which are called "tip" and "ring") of the telephone line which is greater than 5 megohms for all DC voltages up to and including 100 volts. A 5 megohm resistance would correspond to a draw of about 9.6 microamps if the voltage between the tip and ring wires was about 48 volts.
When the handset is lifted "off-hook", the telephone is connected to the line, and current flows through the telephone instrument. In the off-hook state, the telephone is available for use by the customer (or by a device connected to the telephone lines). In accordance with the Code of Federal Regulations, 47 C.F.R. .sctn.68.312, while off-hook, there is no limit with respect to the amount of DC current that may be drawn from the telephone line.
In U.S. Pat. No. 5,454,031 ("the '031 patent"), a dial inbound MIU is described which derives its power from a telephone line, storing the power in a double layer capacitor. As described in that patent, DC current can be drawn from the telephone line, while the telephone is in the on-hook state, to charge the double layer capacitor. Further, that patent describes drawing additional DC current from the telephone line while the telephone is in the off-hook state for charging the double layer capacitor. As described in the '031 patent, when the telephone line is on-hook DC current is drawn through a large resistor (10 megohm). As the specifications for a telephone line requires only a minimum of 21 volts between tip and ring when the telephone is in the on-hook state, the amount of DC current which can be drawn by the circuit described in that patent is limited to as little as 2.1 microamps. While the '031 patent describes the charging of the double layer capacitor using the DC current which is available while the telephone is both in the on-hook state and when the telephone is in the off-hook state, it specifically fails to mention one particularly useful charging opportunity. In particular, 47 C.F.R. .sctn.68.312 permits a telephone device to draw considerably more current when on-hook and ringing, than when on-hook and not ringing, as during a ringing condition, AC current is available.

Dial inbound meter interface unit which derives power from telephone line when telephone is ringing


A navigation system including a GPS receiver; a variable directivity antenna capable of forming a null point in at least one direction; a null point setting unit for setting the null point of the variable directivity antenna in the direction of a GPS satellite that can perform positioning; and a multipath determination unit for determining whether a reception signal from the variable directivity antenna is in a multipath state in accordance with the reception signal.

1. Field of the Invention
The present invention relates to multipath detection methods in global positioning system (GPS) receivers used for detecting the positions of movable bodies, such as vehicles.
2. Description of the Related Art
Receivers, such as GPS receivers, for receiving signals that are spectrum-spread by a direct spread system receive signals from a plurality of earth-orbiting GPS satellites to detect the positions of vehicles, vessels, and the like. GPS receivers using three or more GPS satellites are capable of detecting two-dimensional positions (latitude and longitude). GPS receivers using four or more GPS satellites are capable of detecting three-dimensional positions (longitude, latitude, and altitude).
In-vehicle navigation apparatuses use signals received from the GPS receiver to detect the present position of a vehicle, display a map around the present position of the vehicle on a display, and provide route guidance from the present position of the vehicle to a destination.
A GPS receiver in an in-vehicle navigation apparatus includes an antenna 200 that has a directivity in the zenith direction and that is mounted on a vehicle, for example, as shown in FIG. 9. The GPS receiver receives radio waves from three or four GPS satellites 210 via the antenna 200, performs de-spreading and demodulation on the received signals, and regenerates original transmission signals.
Also, for example, Japanese Unexamined Patent Application Publication No. 5-302972 discloses a positioning apparatus in which antennas A and B having narrow grazing angles of θ1 and θ2, respectively, are installed in a vehicle so that diversity reception is performed using the antennas A and B, as shown in FIG. 10. The positioning apparatus switches time-divisionally between the antennas A and B using a switching circuit, so that information from the GPS satellites 210 received by any one of the antennas A and B is used for positioning calculation. Accordingly, time for position detection can be reduced.
However, the known in-vehicle navigation apparatuses described above have problems. For example, when a vehicle provided with such a navigation apparatus travels on a road surrounded by high-rise buildings or the like in an urban area, a GPS receiver may receive multipath indirect waves due to reflection by the buildings. The GPS receiver may not detect the present position of the vehicle accurately under the influence of multipath because an error may occur in position calculation if waves other than pure direct waves from GPS satellites are used for position detection.
In order to solve such a problem, a beam antenna having a directivity of a particular direction may be used to reduce the influence of multipath. It is, however, practically difficult to use an antenna having a directivity of a particular direction for the GPS receiver because the GPS receiver needs to receive radio waves from a plurality of satellites. In contrast, the GPS receiver may be provided with a multipath detection circuit so that multipath noise can be eliminated from reception signals. This arrangement, however, complicates a circuit configuration of the GPS receiver and increases the cost of the GPS receiver.

Method and system for multipath detection


Servo-assisted steering arrangement for an element pivotable about a steering axis, for example a propeller drive means suspended on a boat transom, said drive means driving a pair of hydraulic steering cylinders (20a, 20b) which connect the drive means to the transom. A manually driven low pressure pump (39), for example a steering wheel pump, communicates both with a cylinder chamber (70, 71) in each steering cylinder (20a, 20b) and with a control valve (36). A motordriven high pressure pump (41) communicates via the control valve with the other cylinder chamber (72, 73) in each steering cylinder. The control valve is disposed so that, when the low pressure pump is driven, it opens a communication both between the pressure side (40) of the high pressure pump and a cylinder chamber (72) in the one cylinder (20b) and between the return side (42) and the corresponding cylinder chamber (73) in the other cylinder.

The present invention relates to a servo-assisted steering arrangement for an element pivotable about a steering shaft, comprising, in a hydraulic circuit, a first hydraulic pump driven by a manual drive means, at least two double-acting hydraulic piston cylinder devices connected in tie hydraulic circuit, each having a cylinder chamber on either side of the respective pistons, said piston cylinder devices being connected between the pivotable element and another element and a second hydraulic pump coupled into the hydraulic circuit, said second hydraulic pump being driven by a drive motor, the hydraulic circuit being divided into two, at least essentially mutually separated first and second partial circuits with a first hydraulic pump in the first partial circuit and a second hydraulic pump in the second partial circuit.
GB 2 159 482, for example, discloses a servo-assisted steering arrangement of the above type for pivoting an outboard motor about a vertical steering axis. The steering arrangement comprises a pair of piston cylinder devices, which are mounted between the ends of a steering arm joined to the engine propeller rig and mounting brackets on the boat hull. The piston rod of one of the piston cylinder devices is mechanically joined to a valve slide in a control valve, the valve housing of which is joined to a steering arm connected to the propeller rig. The control valve thus forms a mechanical connection between the piston rod of the first piston cylinder device and the propeller rig. The cylinder chambers on either side of the associated piston communicate with a steering wheel pump, which, when the steering wheel is turned, pumps hydraulic fluid to one or the other cylinder chamber, depending on the rotational direction of the steering wheel. The circuit, including the steering wheel pump and the first piston cylinder device, forms a low pressure circuit which is separate from a high-pressure circuit in which the control valve is coupled between a motor-driven hydraulic pump and the second piston cylinder device.
When the steering wheel is turned, oil is pumped into one cylinder chamber in the associated piston cylinder device, and at the same time the opposite cylinder chamber is drained. Initially, this leads to a displacement of the valve slide from its closed neutral position to one of its open lateral positions, in which a communication is established between the motor-driven pump and the opposite cylinder chamber in the second piston cylinder device, which leads to displacement of the piston in the opposite direction, which in turn results in the valve housing being displaced in the same direction as the valve slide during the steering movement. As long as the steering wheel is turned, the slide and the housing move together with the slide in the open position. When the turning of the steering wheel and the slide movement stops, the valve closes after a short displacement of the valve housing relative to the slide. The system described thus has a mechanical feedback, which requires that the control valve be movable together with the piston rod of the associated piston cylinder device. One disadvantage of a system with this function, i.e. initial turning of the steering wheel only takes up play and does not result in any steering forces, is that the driver will experience a marked looseness in the system when turning the steering wheel. Another disadvantage is that the total length of the piston cylinder device and the control valve makes it necessary that the distance between the mountings in the boat hull and in the propeller rig be relatively large- which makes it impossible to use the service device described together with certain marine drive units, e.g. an outboard drive unit of the type shown in SE 501 147 (U.S. Pat. No. 5,562,508).
The purpose of the present invention is to achieve a servo-assisted steering device of the type described by way of introduction, which is experienced as being virtually without play and which permits placement of the control valve independently of the placement of the piston cylinder device.
This is achieved to the invention by virtue of the fact that the partial circuits are so connected to the control valve means and to their individual pair of cylinder chambers that the flow in the first partial circuit is directed to one cylinder chamber of the associated pair of cylinder chambers via the control valve means, which at a predetermined pressure open the communication between the second hydraulic pump and one of the cylinder chambers of the associated pair of cylinder chambers, so that the pistons in the respective piston-cylinder devices are displaced in a direction dependent on the flow direction in the first partial circuit.
By controlling the flow from the steering wheel pump parallel to a steering cylinder and to the control valve, a maneuver pressure is achieved immediately in the cylinder striving to pivot the pivotable elements coupled to the cylinders. No play arises on the order of magnitude which is unavoidable in the described known system, in which the hydraulic cylinder coupled to the steering wheel pump only steers a slave cylinder. The servo-assisted steering arrangement according to the invention therefore provides the driver with a better steering feeling and control over the boat. Since the feedback between the steering cylinders, the control valve and the steering wheel pump is completely hydraulic, the control valve can be mounted wherever desired in the boat, which means that it will not, as with the control valve in the described known servo arrangement encroach on the space available for the steering cylinders.
One particular example of a control valve suitable for the steering arrangement according to the invention comprises a valve housing, a valve slide which is displaceable in said housing and which is spring-biased towards a neutral position, in which it breaks the communication between the inlet to and the outlet from the valve housing and a control piston which is joined to the valve slide and is displaceable in a cylinder in the valve housing, said cylinder having, on opposite sides of the control piston, cylinder chambers, each having an inlet and an outlet so that a pressure in either cylinder chamber strives to displace the control piston and thus the valve slide to one of two open positions.
A control valve of this type, which, in a control circuit for a steering device according to the invention, permits manual emergency steering in the event of pressure failure on the high pressure side, is characterized in that the valve slide in one of said two positions establishes communication between a valve housing inlet intended to be connected to the high pressure side in a hydraulic circuit, and one of two connections intended to be connected to individual pressure medium-actuated devices, at the same time as communication is established between the second connection and an outlet from the valve housing intended to be connected to the low pressure side of the hydraulic circuit, non-return valve means arranged in the valve housing permitting, if there is pressure failure on the high pressure side, flow from the low pressure side to the high pressure side when the pressure on the low pressure side exceeds the pressure on the high pressure side.

Servo steering mechanism for boats for example


A sliding device for doors and (24) wardrobe doors provided with multiple adjustments consists of a carriage or slider (10), provided with rollers or bearings (22) for sliding the doors to which a profile section (28) is secured having an embossed and shaped portion (22{circumflex over ( )} of a shape complementary to the profile section of said rollers (22). The carriage or slider (10) comprises a first body or front body (12), having a substantially rectangular plan, and a second body or rear body (14) intended to be connected to the first front body (12); said rear body (14) is provided with opposed substantially cylindrical appendages (16, 18) with a vertical passing-through hole (32) in which respective cylindrical bodies are inserted along which an offset and passing-through threaded hole (36) is bored, to form as many eccentrics (34). In each of the holes (36) a threaded stem or screw (38) is entered, which protrudes from the upper side of the front body (12) on which corresponding holes or slots (32y) are bored.

This invention relates to a sliding device for doors provided with multiple adjustments.
More particularly, this invention relates to a device as defined above, especially suitable for the sliding movement of doors that alternatively close or make passage accessible between two adjacent areas or doors of wardrobes and furniture in general.
As is known, the sliding doors that separate two areas are often used based on their practicality, since they do not require cantilevering spaces for opening and, in certain solutions, they are entered in a hidden position on both sides of the wall. Even from an aesthetic point of view, the sliding doors are therefore appreciated and increasingly widespread, both in residential areas and in offices and commercial premises. To allow the sliding of these doors, specific devices are used, comprising carriages that are moved along an upper guide secured to the wall and, at the same time, secured to the upper end or header of the door to be moved; the connection between the carriages and the door is generally achieved through an appendage integral with the lower part of each carriage, which projects from a slot extending longitudinally in the above-mentioned guide. Said appendage includes on its free end a plate or the like, which by means of screws or equivalent retaining means is constrained to the door. A solution of this type is described in the EP 2 913.468 patent of the same applicant.
As an alternative, the door is provided, on the internal side facing the wall, with a shaped profile section whose upper part defines a contoured profile section complementary to that of a pair of wheels or rollers of a fixed carriage, i.e. secured to the wall, to be precisely hooked to said rollers; in this case, the opening and closing movement of the door takes place according to the sliding of the profile section on the wheels or rollers of the fixed carriage; this solution is particularly advantageous since the device as a whole is hidden from view, except for a plastic cap that closes the headers of the profile section. In both hypotheses, a complementary and opposed lower guide completes the device; said lower guide is screwed to the floor and includes a projecting appendage such as a pin or the like that engages along a slot formed at the lower end of the door. These known devices for sliding doors, although capable of performing the function to which they are designed, however, exhibit some drawbacks, connected above all to the adjustment of the carriages during installation. In this regard, an important adjustment concerns the distance of the door from the wall and is necessary if it does not present a perfectly planar development but includes one or more embossed or recessed areas with respect to others. In these cases, it is necessary to use spacers, which are interposed between the wall and the fixed carriage, on which the shaped profile section integral with the inner side of the door moves when sliding; the positioning of such spacers, which have the purpose of keeping the door for its entire width homogeneously spaced from the wall, is complex and laborious, since it requires the release of the door with respect to the carriage. This adjustment is also approximate and a further difficulty is encountered when positioning three spacers in correspondence with the three wall securing screws of the carriage without letting them fall to the ground. Finally, the fact of having a support of the fixed carriage located on the spacers does not guarantee an optimal stabilization of the carriage with respect to the wall.
The fixed carriages of the sliding devices, also called "sliders", are also provided with means for their adjustment in a vertical direction, that is to say with respect to the floor in which a guide for moving the door along the lower edge is generally integrated. Said vertical adjustment is obtained by means of a screw placed above the center of the carriage and may be difficult, being necessarily carried out prior to the insertion of the side caps that close the opposed headers of the profile section secured to the door, which, as explained above, is hooked and slides on the wheels of the carriage bound to the wall. It is also necessary, in order to perform the aforementioned vertical adjustment, that the door is open and in an end-of-stroke position.
The purpose of this invention is to obviate the disadvantages mentioned above.
WO 2012 073215 discloses the manufacture solution of a sliding door comprising a shutter able to move between two end opening and closing positions; said door is provided with means for supporting and guiding the shutter, which, in turn, comprise rotating items for slidably supporting longitudinal guide devices, secured above the shutter itself and also associated with its lower edge.
The French patent no. FR 46590 describes instead a sliding door suspended on eccentric pins; on the door frame there are lateral rollers, eccentrically adjustable in the same manner as the suspension means, so as to be able to suitably adjust the vertical position of said door. This sliding guide solution aims to avoid vibrations and noises during door movement.

Sliding device for doors and wardrobe doors provided with multiple adjustments


A system is provided to monitor targeted pest populations, disease, presence of transgenic and non-transgenic plants, or targeted pest population in a transgenic crop using remote imagery to discern differences in crops along with pest infestation in all crop varieties. The system relies on the fact that plant leaves are known to change color based on stress, herbivory, and other environmental factors. The system provides a special camera that can see reflected light energy across the visible and near infrared (about 400-1000 nm) to identify these effects.

Sustainable agriculture is a long-term approach that combines efficient production with wise stewardship of the earth's resources. Sustainable agriculture includes developing environmentally benign production techniques. One such method involves the development of transgenic crops that incorporate genes that product toxic gene products, or proteins targeting a specific pest larval form. Incorporating the gene into plants eliminates or vastly reduces the amount of traditional pesticides that must be used on crops. The most serious threat to the efficacy of transgenic plants is the evolution of resistance to expressed toxins by insect pests.
Transgenic plants that produce insecticidal substances, however, should be subject to careful testing to ensure human safety and to minimize adverse environmental impacts. Potential environmental impacts unique to transgenic plants include transfer (by cross-pollination) of the new insecticidal gene to wild or weedy relatives of the transgenic crop, as well as the establishment of self-seeded or vegetative propagated crops such as weed in either managed or natural habitats.
The United States Environmental Protection Agency considers preservation of susceptibility to transgenic toxins to be in the public interest, and proteins such as those produced by Bacillus thuringienses are therefore worthy of extra protection (U.S. Environmental Protection Agency and U.S. Department of Agriculture, 1999). Insect resistance management (IRM) relates to practices aimed at reducing the potential for insect pests to become resistant to a pesticide or transgenic plant. IRM is important for transgenic crops, particularly for those crops expressing Bacillus thuringienses proteins (commonly called Bt crops), because insect resistance poses a threat to the future use of microbial Bt formulation in organic farming and Bt technology as a whole. Scientists, public interest groups, and organic growers and other farmers have expressed concern that the widespread planting of such genetically modified plants will hasten insect resistance to Bt endotoxins, as well as to other toxins produced by transgenic plants.
Under the Federal Insecticide, Fungicide and Rodenticide Act (FIFRA), the U.S. Environmental Protection Agency requirements for transgenic crop registration are designed to ensure that there will be no unreasonable, adverse effects from the use of a pesticide when economic factors are fully considered. With the application of Bt technology, the EPA has stated that it is working to prevent what would happen if Bt no longer could control insect pests, and more toxic insecticides had to be used in its place. In 2000 the EPA imposed new IRM requirements on registered transgenic crops to combat insect resistance to Bt endotoxins. Sound IRM will prolong the life of transgenic insecticides, and adherence to IRM plans benefits growers, producers, researchers, and consumers.
The U.S. EPA has required seed producers to formulate a program of crop stewardship to include an active crop monitoring program and the adoption of an insect resistance management program as part of registration for transgenic crops that produce an insecticide protein. For example, field corn is a crop in which genes for insecticidal proteins have been inserted to protect against both the European corn borer and the corn rootworm.
The current monitoring program is a shared activity across the industry. This monitoring program is based on sampling for resistant insects during the crop season in four discrete areas that are considered to be potential areas of concern. The insects collected are subjected to a dose-response assay to detect if any of the larvae are resistant to the toxin expressed in the crop plant. The IRM program involves the insecticide protein coupled with a refuge of non-transgenic plant hybrids.
Current EPA resistance management for Bt corn hybrids for European corn borer is 20% of the corn acreage plants to a non-Bt corn hybrid of similar maturity within one half mile of the Bt-corn field. It is recommended that the hybrids be planted at approximately the same date as the transgenic crops. EPA requirements for Bt-corn hybrids for corn rootworm is much the same, with the modification that the refuge must be within the same filed or in an adjacent field. A one half mile distance is not permitted.
The refuge requirement is a legal requirement for companies marketing Bt-corn hybrid. The seed technology companies with the registration are responsible for assuring that framers planting their hybrids meet compliance standards. Failure to meet these standards can result in a company losing its registration or right to sell the hybrids within an area where a significant number of farmers are out of compliance with refuge management regulations.
Although implementation of refuge areas in a resistance management program is a legal requirement, policing the regulation is a formidable task. For this reason, remote sensing technology is considered to be the best method of obtaining a general view of the degree of compliance across large geographic areas and within high adoption areas.
Presently, monitoring of transgenic corn acreage for development of pest resistance rests on the collection of viable pest samples from four specific areas in the U.S. corn belt. There have been concerns that the seed industry is unable to report information about resistance outbreaks in a timely fashion. Since resistance development has been seen to be a "local" phenomenon, the course scale of the sampling used in current monitoring programs could easily miss areas or development of resistance.
The landmass of more than 25 million acres of transgenic corn alone does not permit the level of scrutiny to properly identify resistance development economically at an acre by acre level of inspection.
It is also useful to monitor groups of plants or areas of agricultural or other types of growth for conditions of the plants, such as response to physiological stress, insect infestation, and the like.

Optical system for plant characterization

The United States of America as represented by the Administrator of the United States Environmental Protection Agency


A semiconductor integrated circuit includes a processor for executing application code from a memory and a verifier processor arranged to receive the application code via the same internal bus as the processor. The verifier processor performs a verification function to check that the application code is authentic. The verifier processor runs autonomously and cannot be spoofed as it receives the application code via the same internal bus as the main processor.

In conditional access devices for pay television, or any other device using memory and requiring security, there is a need to provide flash memory but to avoid hacking. Hacking is the unauthorized placing of software in memory to override security features. A known way of attempting to prevent hacking is to use some form of checking instructed by ROM memory to ensure that an application code stored in flash memory is correct. Such a device is shown in FIG. 1.
A flash memory 2 has a boot sector 6 and an application sector 16. A CPU 10 is arranged to run application code from the flash memory 2 retrieved over an interface 12 via bus 8 EMI 20 and bus 18. The security is provided by the CPU 10 booting from a boot ROM 3 which contains code to check the boot sector 6 of the flash memory. This is done once by the CPU producing a function of the code in the boot sector and comparing with a stored signature on startup. The CPU then jumps to the code in the boot sector 6 if it passes the check. However, it is now known that there is a relatively simple way of hacking such a security arrangement. When the CPU 10 boots up using code from the ROM 3, the CPU checks that the code in the boot sector 6 is correct. The weakness is that the process of power on, CPU boot and checking the flash takes a predictable number of clock cycles of the CPU clock. Thus, to hack the system, a hacker places code in an unchecked part of the flash memory 2 and forces the CPU to read from that part of the memory after a predetermined number of clock cycles by fixing an external address line.
The CPU 10 thereafter runs from unchecked code and no further checks are conducted, because the verification of code is only conducted on boot up from the ROM 3.

This patent is subject to a terminal disclaimer.

STMicroelectronics (Research & Development) Limited


A system for producing a torrefied biomass that at least partially replaces coal in coal-fired processes. The system comprises: a feed bin for receiving carbonaceous feedstock, conveying the ingested feedstock and treating the ingested feedstock to produce modified feedstock; a dryer that treats the modified feedstock to produce dried feedstock, the dryer including a heater that warms the dried feedstock to produce heated feedstock; a torrefaction subassembly; a particle downsizing system; a separator for separating minerals from the feedstock; and a compactor.

(1) Field of the Invention
One aspect of this disclosure relates to a manufacturing apparatus and process to produce a torrefied biomass or biocoal that can replace coal in coal-fired systems such as gasification, pyrolysis and combustion.
(2) Background Art
Biomass aids in meeting the targets established by the Kyoto Protocol and the Copenhagen Accord. Also, using biomass for energy production can meet the Renewable Energy Portfolios of U.S. States.
Initially, using raw-biomass seemed the most promising solution to reduce greenhouse gases. Indeed, co-firing raw-biomass in coal-fired boilers has been attempted for demonstration and commercial purposes. However, problems have been encountered, the most important of which is grindability of the raw-biomass (others are high bulk volume moisture content, low calorific value, hydrophobic material, thermal instability and production of undesired tars). Using torrefied-biomass, or simply biocoal, as a replacement of coal solves many of the problems encountered in using raw-biomass because during torrefaction, hemicelluloses, made of polysaccharides, is decomposed and changes the viscoelastic properties of the biomass and improves grindability. Furthermore, biocoal will merge into existing technologies with no added technological complications, nor large capital or operation costs.
It is expected that electricity production by coal-fired utility boilers will continue to be stable at ˜45% of total production in the next 30 years. Coal's efficiencies and energy-generation capabilities are well documented. However, it is accompanied by high levels of CO2 and other emissions. Biocoal offers many of the same benefits of coal and also: (1) significantly reduces emissions (CO2, NOx, SOx, mercury, PAH, particulates); (2) can be cost-competitive with coal. Replacing 20-25% of coal by biocoal can be achieved in 10 years. Therefore it is important to develop torrefaction processes. Torrefaction has been shown to decrease volatile matter in biomass, making biocoal safer for grinding due to a lower risk of self-ignition. Temperature and residence time were found to have a great effect on: (1) the chemical properties and durability of torrefied-biomass; (2) the behavior of oxidation biocoal; (3) syngas production in gasification; (4) increasing the hydrophobic nature of biomass. As a consequence, biocoal can be considered a premium drop-in biofuel with properties similar to coal that can be controlled to match those of a given coal.
Among the patent references considered before filing this application were:
US20080263891 A1: Process for treating lignocellulosic material, and apparatus for carrying out the same;
US20030221363: Process and apparatus for making a densified torrefied fuel;
US20090250331 A1: Auto thermal and mobile torrefaction devices;
US20090272027 A1: Method for the preparation of solid fuels by means of torrefaction as well as the solid fuels thus obtained and the use of these fuels;
US20110179700 A1: System and methods for torrefaction and processing of biomass.


A specialized package for shipping and using fiber optic cable which simplifies handling prior to installation, and serves as a storage device after the cable has been installed. The disclosed device comprises a fiber board box of planar configuration with an integral lid secured in closed position by tuck tabs. Positioned within the box are a pair of planar foam layers each defining a congruent circular opening. Positioned within the opening is a flat spool having a core and at least one detachable end cap upon which the fiber optic cable is coiled, and from which project a pair of connectorized ends. When the package is closed, the connectorized ends are gently clamped between the foam layers, thus protecting the same against damage during shipment.

This invention relates generally to the field of fiber optic cables, and more particularly to an improved means and method for packaging and storing such cable to eliminate the possible damage resulting from excessive handling of the same prior to ultimate installation.
As purchased from cable manufacturers, optical cable is installed on very large spools holding integral lengths of cables, often measuring many hundreds of meters. This large length is subsequently cut to smaller standardized lengths of cable ranging in length between 10 and 25 meters, and connectorized at each end for use in telephone central offices and similar locations where a connectorized cable is employed to stand a distance normally substantially smaller than the length of the cable. The excess cable is wound in a coil of diameter greater than the minimum bend radius and stored in a cabinet drawer or other suitable protected location, since it is desirable for technical reasons to have as few joints in the cable as possible.
As contrasted with copper wire and cables comprised of copper wire, fiber optic cable is quite fragile and easily damaged if improperly handled. Thus, there arises a need to protect the fiber after it has been cut to standardized length and fitted with connectors.


A heat exchange section includes a first air heat exchanger having three vertical side surfaces through which air passes, the three side surfaces being arranged in a substantially U shape when viewed in plan, and a second air heat exchanger which is formed in a substantially flat plate shape, arranged obliquely to be away from an open surface of the first air heat exchanger toward a top end thereof, and has a single sloping surface through which the air passes.

A refrigeration apparatus such as an air conditioner has been known.
For example, Patent Document 1 discloses a refrigeration apparatus including a pair of air heat exchangers, and a support on which the pair of air heat exchangers is placed. Each of the air heat exchangers has three side surfaces that are arranged substantially in a U shape when viewed in plan. As illustrated in FIGS. 3 and 4 of Patent Document 1, the two air heat exchangers are arranged such that their open surfaces face each other. The two air heat exchangers respectively have center side surfaces which are inclined so that their outer faces are oriented obliquely downward. That is, the two air heat exchangers are arranged substantially in the shape of V when viewed from the side.


A method, an article of manufacture and apparatus for providing user-specific error analysis for a document. Specifically, the invention provides for identifying user-specific proclivities for confusing particular words which, while grammatically correct, are not used as intended by the user. The proclivities are tracked by recording changes made by the user while editing a document. The information collected while tracking the changes is then used to identify problem words to the user at a later period in time.

1. Field of the Invention
This invention relates to text editing systems, and, more particularly, the invention relates to a method, an article of manufacture and apparatus for performing spelling analysis.
2. Background of the Related Art
Computer-based text editors can be found in word processors and spreadsheets for providing spelling and grammar correction. One purpose of document checking software is to assist a person in producing a high quality document without spelling and grammar mistakes. Implicit in producing a high quality document is that corrections be made in the least amount of time and that the software be able to accurately detect a user's mistakes.
Conventional spell and grammar checking software analyze a user's document for errors by comparing the words in the user's document to the words in the software's database. If words in the user's document do not match words in the software's database, the user's words are highlighted, and the user is given the option to change the word.
However, one problem with conventional spell and grammar checking software is that the software analyzes a user's document with no reference to a user's spelling habits. For instance, a user may have a habit of typing the word "an" rather than the word "and". Since the word is spelled correctly, the word would not be detected by a conventional software.
A second problem with conventional spell and grammar checking software is the inability of the software to detect a user's problem words. For instance, the two sentences, "Thomas and Eagle went to the store" and "Thomas an Eagle went to the store" are both grammatically correct. Hence, conventional software would not be able to detect the user's problem words "and" and "an". Therefore, the user would have to manually detect the correction. This results in inefficient use of time and lost productivity for the user.
Therefore, a need exists in the art for a method, an article of manufacture and apparatus for providing spelling analysis in an efficient manner.

Method and apparatus for providing spelling analysis

International Business Machines Corporation