An electron gun provides an improved focusing characteristic of electron beams surely and effectively, and permits position alignment to be relatively easy in assembling thereof. In an electron gun which includes a cathode for discharging electrons and a plurality of grids each having electron passing-through holes for guiding the electrons discharged from the cathode unidirectionally, an electron dischargeable region is formed in an electron discharging plane of the cathode, which is band-shaped. In addition, the length of the band-shaped area constituting the electron dischargeable region on its shorter side is less than 80% of the diameter of the area from where electrons are discharged when a practical maximum current is taken out without limiting the electron dischargeable region.

The present invention relates to an electron gun for a cathode ray tube which is used for CRT, electron microscope or an electron beam exposure device, and more particularly to an improvement in a cathode of the electron gun.
FIG. 19 is an enlarged sectional view of the vicinity of a cathode of a conventional electron gun as disclosed in JP-A-7-85807. In FIG. 19, reference numeral 1 denotes a heater. Reference numeral 2 denotes a sleeve composed of an inner sleeve 2A of a cylinder of molybdenum formed so as to surround the heater 1 and an outer sleeve 2B covering the inner sleeve 2A. The upper side (discharging side of electrons) of the inner sleeve is blocked. The upper end of the outer sleeve 2B is also blocked like the inner sleeve 2A whereas its center is opened. Reference numeral 3 denotes an electron dischargeable (i.e., discharge) region, and reference numeral 4 denotes a cathode pellet.
The cathode used in the above conventional electron gun is called an impregnated cathode. The cathode pellet 4 is formed of a porous substrate of tungsten (W) impregnated with aluminate compound of BaO, CaO and Al.sub.2 O.
The cathode pellet 4 is fixed on the upper central surface of the blocking portion of the inner sleeve 2A and exposed from the opening portion of the outer sleeve 2B. This exposed area of the cathode pellet 4 constitutes an electron dischargeable region 3. The sleeve 2 and cathode pellet 4 constitutes a cathode 5.
Above and apart from the cathode 5, a first grid 6 is provided. The first grid 6 is provided with a first grid electron passing through-hole 7. Above the first grid 6, a second grid 8 is arranged, which is provided with a second grid electron passing through-hole 9. The first grid 6 and the second grid 8 are formed of a conductive plate.
FIG. 20 shows an entire schematic configuration of a cathode ray tube used in the conventional electron gun. In FIG. 20, reference numeral 10 is a fluorescent screen opposed to the cathode 5.
As seen from FIG. 20, on the side of the fluorescent screen 10, the third grid 11, fourth grid 12 and fifth grid 13 are provided. These third, fourth and fifth grids are formed of a conductive plate and provided with an electron passing through-hole, respectively.
It should be noted that the cathode 5 and the plural grids 6, 8, 11, 12 and 13 are secured by a supporting body (not shown) so that they are in a proper alignment with one another.
Further, the first grid electron passing through-hole 7 and second grid electron passing through-hole 9 are formed of cylindrical holes having equal diameters located on the same axis, respectively. On the extending line of the axis, the cathode pellet 4 is located. The cathode pellet 4 is formed in a region around the above axis, and has a smaller area than that of the first grid electron passing though-hole 7.
An explanation will be given of the electron gun having the above configuration. To the first grid 6, a predetermined voltage, lower than that applied to the cathode 5, is applied. To the second grid 8, a predetermined voltage, higher than that applied to the cathode 5, is applied. In this way, by applying suitable voltages to the cathode 5, first grid 6 and second grid 8, electrons can be taken out to side of the fluorescent screen 10. The amount of electrons to be taken out, i.e., discharging current, can be adjusted by varying the voltage at the cathode 5 or first grid 6. Also, to the third grid 11, fourth grid 12 and fifth grid 13, predetermined voltages are applied. Thus, the electrons discharged from the surface of the cathode 5 by the field lens composed of the cathode 5 and plural grids 6, 8, 11, 12 and 13 are incident on the fluorescent screen 10 in their focused state.
As described above, the main configuration of the electron gun is provided with the cathode 5 for discharging electrons and plural grids 6 and 8 provided with the electron passing though-holes 7 and 9 for unidirectionally guiding the electrons discharged from the cathode 5.
FIG. 21 is a view for explaining the locus of the electrons discharged from the cathode 5, which illustrates the electron locus in the neighborhood of the cathode on its section. In FIG. 21, the abscissa represents a distance (mm) from the electron discharging plane of the cathode 5 toward the electron discharging side, and the ordinate represents the distance (mm) from the center axis on the electron discharging plane. Reference numeral 14 denote electron loci of the electrons discharged from the cathode 5 and reference symbol D denotes an equi-potential line. As seen from FIG. 21, the electrons discharged from the neighborhood of the cathode 5 provide crossover points in the vicinity of the fluorescent screen (right side of FIG. 21), whereas the electrons discharged from positions remote from the central axis Z provide cross-over points in the neighborhood of the electron discharging plane (left side in FIG. 21). Specifically, the force acting on electrons is in the direction normal to the equi-potential line. The field lens including the cathode 5, first grid 6 and second grid 8 is regarded as a spherical lens. Therefore, the electron beams discharged from the neighborhood of the center axis Z of the electron discharging plane cross over substantially at a single point. On the other hand, the electrons discharged from the positions apart from the center axis Z are subjected to the strong force directed to the center axis so that they provide cross-over points at positions nearer to the electron discharging plane than the electrons discharged from the neighborhood of the center axis Z do.
For this reason, reducing the diameter of an electron dischargeable region can eliminate the electron discharging from the positions remote from the center axis Z so that occurrence of "halo" due to the electron discharge therefrom can be reduced. Thus, the converging characteristic can be improved. In this way, the electron gun having the above configuration, in which the electron dischargeable region 3 has a smaller area than that of the first grid electron passing through-hole 7, can improve the convergence characteristic of electrons.
The first problem of the above conventional electron gun is to require the coincidence of the respective center axes of the electron dischargeable region 3, first grid passing through-hole 6 and second grid electron passing through-hole 8, which makes adjustment of axis alignment difficult.
The second problem of the conventional electron gun is as follows. In the case where the area of the electron dischargeable region 3 is made excessively smaller than that of the first grid electron passing through-hole 7, the electron convergence characteristic is not necessary improved in a greater degree than in the electron gun in which the area of the electron dischargeable region 3 is larger than that of the first grid electron passing through-hole 7.
The second problem will be described below in more detail. Where the electron dischargeable region is so large that it does not limit the electron discharging region, the electron discharging region in the electron discharging plane is determined mainly by the discharging current amount although it varies according to the type of the electron gun. For example, the electron gun used for CRT has an upper limit of the discharging current amount in a practical use according to the use and performance of CRT.
The upper limit in practical use will be explained. For example, the CRT for display monitor generally requires the image luminance as high as about 100 cd/cm.sup.2. In the case of a color monitor, electrons discharged from the electron discharging plane of the cathode are incident on the aperture grill provided with an electron passing slits or the shadow mask provided with electron passing through-holes according to the luminescent pattern of the luminescent screen. The electrons having passed through the electron passing slits or electron passing through-holes are incident on the fluorescent plane. Thus, the light flux substantially proportional to the incident amount of electrons is discharged from the fluorescent body and passes through the fluorescent glass which is a screen so that the light flux is discharged externally from the CRT.
For example, as regards a certain model of electron gun, the aperture rate of the aperture grill or shadow mask, light emitting efficiency of the fluorescent body, permeability of the fluorescent glass, etc., can be regarded constant. For this reason, the substantial maximum current amount which must be discharged from the cathode in order to obtain predetermined image luminance can be uniquely determined. The upper limit of performance will be explained below. For example, as matters now stands, generally, the CRT for HDTV (High Definition Television) does not have sufficient luminance. The sufficient luminance can be obtained by increasing the current amount discharged from the cathode. But, an increase in the current commonly deteriorates the convergence in an electron beam. On the other hand, because the HDTV displays video images with high resolution, the HDTV is required to converge the electrons discharged from the cathode so that the current amount cannot be simply increased in order to maintain the resolution constant. Thus, the approximate maximum current amount which can be discharged in order to obtain a predetermined image quality can be determined uniquely.
The maximum current required to obtain the maximum luminance in a practical range in a certain model of CRT using an electron gun is called a practical maximum current. It can be defined as follows. The maximum luminance in the practical range is a necessary and sufficient value as luminance of this kind of model or a substantial value that this model can spell out as performance in a catalogue. The luminance that the model can provide but leads to the image quality which is not practical because of greatly reduced focusing does not refer to the maximum luminance in the practical range. Even when the practical maximum current is taken out, in almost all cases, the area of the electron discharge region is not larger than that of the first grid electron passing through-hole 7 and is about 1/4 as large as thereof (i.e. 1/2 in diameter).
For example, assuming that the first grid electron passing through-hole 7 has a disk shape with a diameter of about 0.4 mm, even when the practical maximum current of the electron gun is taken out, the diameter of the electron discharging region in the electron discharging plane of the cathode may be about 0.2 mm. In this case, even when the electron dischargeable region is disk-shaped with a diameter of 0.3 mm which is smaller than that of the first grid electron passing through-hole 7, the effect of improving the focusing characteristic cannot be obtained. Further, even when the electron dischargeable region 3 has a diameter of 0.19 mm, the great effect of improving the focusing characteristic cannot be obtained because the amount of discharged electrons is little in the vicinity of the boundary of the electron discharging region.

Electron gun having a cathode with limited electron discharge region


The method of generating an address scramble includes receiving address information for each of a plurality of memory cells included in a semiconductor memory device and the address information that includes a logical address and a physical address corresponding to each of the memory cells; generating an address scramble logical expression, the address scramble logical expression relating logical addresses to physical addresses based on the address information; and reducing the address scramble logical expression using a given algorithm.

Example embodiments of the inventive concepts relate to a semiconductor test device, and more particularly, to a semiconductor test device for automatically generating an address scramble and/or a method of generating an address scramble using the same.
With the increase in the storage capacity and operation speed of a semiconductor memory device, the number of transistors included in the semiconductor memory device has increased. Accordingly, the probability of occurrence of failures in semiconductor memory devices has also increased. Therefore, it has been important to probe and detect the failures.
To test a semiconductor memory device for a failure, data is written to a plurality of memory cells in the semiconductor memory device and then data is read from the memory cells. The data that has been written is compared with the data that has been read, so that the semiconductor memory device is judged good or bad based on a comparison result.
A memory cell array of a semiconductor memory device does not have a structure in which row addresses and column addresses sequentially increase. Therefore, an investment in improving equipment and commitment of work force is required to realize an address scramble.
In addition, the semiconductor memory device has a complex and irregular block structure in a memory cell array in order to improve its characteristics and optimize its area. Accordingly, the probability of occurrence of human errors in making a program is increasing.
In a test process, an address scramble is generated using a partial test in which a test operation is carried out on only part of memory cells in order to increase productivity. For the partial test, a method of matching a logical address and a physical address one on one and a method of developing a logical expression for each address pin is used.
However, the method of matching the logical and physical addresses one on one is restrictively used in certain test devices. The method of developing the logical expression is likely to cause human errors and delay compiling time since the logical expression is massive.
Therefore, it is desired to generate an address scramble that is not restricted to certain semiconductor test devices based on the block structure of semiconductor memory device.

Semiconductor test device and method of generating address scramble using the same


The invention provides novel inhibitors of hedgehog signaling that are useful as a therapeutic agents for treating malignancies where the compounds have the general formula I:

Hedgehog (Hh) protein was first identified in Drosophila melanogaster as a segment-polarity gene involved in embryo patterning (Nusslein-Volhard et al., Roux. Arch. Dev. Biol. 193: 267-282 (1984)). Three orthologs of Drosophila hedgehog (Sonic, Desert and Indian) were later identified to occur in all vertebrates including fish, birds and mammals. Desert hedgehog (DHh) is expressed principally in the testes, both in mouse embryonic development and in the adult rodent and human; Indian hedgehog (IHh) is involved in bone development during embryogenesis and in bone formation in the adult; and, Sonic hedgehog (SHh) is expressed at high levels in the notochord and floor plate of developing vertebrate embryos. In vitro explant assays as well as ectopic expression of SHh in transgenic animals have shown that SHh plays a key role in neuronal tube patterning (Echelard et al., supra.; Ericson et al., Cell 81: 747-56 (1995); Marti et al., Nature 375: 322-5 (1995); Krauss et al., Cell 75, 1432-44 (1993); Riddle et al., Cell 75: 1401-16 (1993); Roelink et al, Cell 81:445-55 (1995); Hynes et al., Neuron 19: 15-26 (1997)). Hh also plays a role in the development of limbs (Krauss et al., Cell 75: 1431-44 (1993); Laufer et al., Cell 79, 993-1003 (1994)), somites (Fan and Tessier-Lavigne, Cell 79, 1175-86 (1994); Johnson et al., Cell 79: 1165-73 (1994)), lungs (Bellusci et al., Develop. 124: 53-63 (1997) and skin (Oro et al., Science 276: 817-21 (1997)). Likewise, IHh and DHh are involved in bone, gut and germinal cell development (Apelqvist et al., Curr. Biol. 7: 801-4 (1997); Bellusci et al., Dev. Suppl. 124: 53-63 (1997); Bitgood et al., Curr. Biol. 6: 298-304 (1996); Roberts et al., Development 121: 3163-74 (1995)).
Human SHh is synthesized as a 45 kDa precursor protein that upon autocatalytic cleavage yields a 20 kDa N-terminal fragment that is responsible for normal hedgehog signaling activity; and a 25 kDa C-terminal fragment that is responsible for autoprocessing activity in which the N-terminal fragment is conjugated to a cholesterol moiety (Lee, J. J., et al. (1994) Science 266, 1528-1536; Bumcrot, D. A., et al. (1995), Mol. Cell Biol. 15, 2294-2303; Porter, J. A., et al. (1995) Nature 374, 363-366). The N-terminal fragment consists of amino acid residues 24-197 of the full-length precursor sequence which remains membrane-associated through the cholesterol at its C-terminus (Porter, J. A., et al. (1996) Science 274, 255-258; Porter, J. A., et al. (1995) Cell 86, 21-34). Cholesterol conjugation is responsible for the tissue localization of the hedgehog signal.
At the cell surface, the Hh signal is thought to be relayed by the 12 transmembrane domain protein Patched (Ptc) (Hooper and Scott, Cell 59: 751-65 (1989); Nakano et al., Nature 341: 508-13 (1989)) and the G-protein-coupled-like receptor Smoothened (Smo) (Alcedo et al., Cell 86: 221-232 (1996); van den Heuvel and Ingham, Nature 382: 547-551 (1996)). Both genetic and biochemical evidence support a receptor model where Ptc and Smo are part of a multicomponent receptor complex (Chen and Struhl, Cell 87: 553-63 (1996); Marigo et al., Nature 384: 176-9 (1996); Stone et al., Nature 384: 129-34 (1996)). Upon binding of Hh to Ptc, the normal inhibitory effect of Ptc on Smo is relieved, allowing Smo to transduce the Hh signal across the plasma membrane. However, the exact mechanism by which Ptc controls Smo activity still has yet to be clarified.
The signaling cascade initiated by Smo results in activation of Gli transcription factors that translocate into the nucleus where they control transcription of target genes. Gli has been shown to influence transcription of Hh pathway inhibitors such as Ptc and Hip1 in a negative feedback loop indicating that tight control the Hh pathway activity is required for proper cellular differentiation and organ formation. Uncontrolled activation of Hh signaling pathway are associated with malignancies in particular those of the brain, skin and muscle as well as angiogenesis. An explanation for this is that Hh pathway has been shown to regulate cell proliferation in adults by activation of genes involved in cell cycle progression such as cyclin D which is involved in G1-S transition. Also, SHh blocks cell-cycle arrest mediated by p21, an inhibitor of cyclin dependent kinases. Hh signaling is further implicated in cancer by inducing components in the EGFR pathway (EGF, Her2) involved in proliferation as well as components in the PDGF (PDGFα) and VEGF pathways involved in angiogenesis. Loss of function mutations in the Ptc gene have been identified in patients with the basal cell nevus syndrome (BCNS), a hereditary disease characterized by multiple basal cell carcinomas (BCCs). Dysfunctional Ptc gene mutations have also been associated with a large percentage of sporadic basal cell carcinoma tumors (Chidambaram et al., Cancer Research 56: 4599-601 (1996); Gailani et al., Nature Genet. 14: 78-81 (1996); Hahn et al., Cell 85: 841-51 (1996); Johnson et al., Science 272: 1668-71 (1996); Unden et al., Cancer Res. 56: 4562-5; Wicking et al., Am. J. Hum. Genet. 60: 21-6 (1997)). Loss of Ptc function is thought to cause an uncontrolled Smo signaling in basal cell carcinoma. Similarly, activating Smo mutations have been identified in sporadic BCC tumors (Xie et al., Nature 391: 90-2 (1998)), emphasizing the role of Smo as the signaling subunit in the receptor complex for SHh.
Various inhibitors of hedgehog signaling have been investigated such as Cyclopamine, a natural alkaloid that has been shown to arrest cell cycle at G0-G1 and to induce apoptosis in SCLC. Cyclopamine is believed to inhibit Smo by binding to its heptahelical bundle. Forskolin has been shown to inhibit the Hh pathway downstream from Smo by activating protein kinase A (PKA) which maintains Gli transcription factors inactive. Despite advances with these and other compounds, there remains a need for potent inhibitors of the hedgehog signaling pathway.

Pyridyl inhibitors of hedgehog signalling

Abstract: wherein A, X, Y R1, R2, R3, R4, m and n are as described herein.


A method for modifying a fine particle dispersion liquid has excellent dispersibility and dispersion stability. In this method for modifying a fine particle dispersion liquid having improved fine particle dispersibility, impurities included in an agglomeration of fine particles contained in the fine particle dispersion liquid are released into the dispersion liquid by applying physical energy to the agglomeration and performing dispersion processing for dispersion into particles that are smaller than the agglomeration of fine particles. The impurities are removed from the dispersion liquid by means of a removal unit provided with a filtration membrane before reagglomeration is caused by the impurities.

Fine particle is the material used in wide fields such as a semiconductor, a tonner, a paint, a ceramic, a metal, a drug, a cosmetic, a chemical, and a color filter, wherein when these materials are made to fine particles, new characteristics emerges so that various production methods thereof have been proposed.
These fine particles are actually used by dispersing them in various solvents, wherein when they are in the state of aggregates, namely in the state of forming secondary particles, characteristics as nanoparticles cannot be fully expressed in many cases. Especially when they are made to fine particles with the size of 200 nm or less, the characteristics thereof improve; however, in it there is a problem of readily forming aggregates. Therefore, a method for producing fine particle dispersion solution with which not only dispersion property of the fine particles is controlled but also the particles are dispersed to primary particles is being wanted.
When fine particles are produced in a liquid phase, in general, a fine particle raw material solution obtained by dissolving fine particle raw materials into a solvent is mixed with a separating solvent capable of separating the fine particles from the raw material solution thereof so as to separate the fine particles. Especially as disclosed in Patent Literatures 1 and 2, when the fine particles are separated in between processing surfaces which are disposed so as to be able to approach to and separate from each other as well as to rotate relative to each other, the fine particle dispersion solution with high dispersion can be obtained comparatively easily.
However, when the liquid phase method is used, the fine particle dispersion solution includes impurities derived from the fine particle raw material solution or from the fine particle separating solvent. Therefore, during a certain period after separation of the fine particles, a high dispersion state can be retained; however, because of these impurities, with a passage of time the fine particles are aggregated in the fine particle dispersion solution to cause precipitation thereof in many instances. In the case where a fluid processing apparatus with a forced thin film type provided with processing surfaces which are disposed so as to be able to approach to and separate from each other as well as to rotate relative to each other, the equipment being described in Patent Literatures 1 and 2, is used, the fine particles immediately after separation thereof have small and uniform particle diameters and are originally highly dispersive, so that in some instances these are highly influenced by aggregation with passage of time.
In general, impurities are removed from the fine particle dispersion solution like this in the way as follows. Namely, the fine particle dispersion solution is concentrated by a method such as centrifugal separation, suction filtration, or filter press, and then, after a washing solution such as pure water is charged to it; the centrifugal separation, the suction filtration, or the like is repeated so as to remove the impurities in the fine particle dispersion solution.
For example, in Patent Literature 3, a purification method for removing by separating ionic impurities included in fine particles is disclosed. In Patent Literature 3, by using membrane filtration, ionic impurities are removed by separation together with a permeated solution to obtain a concentrated fine particle dispersion solution, into which water is added so as to dilute the solution to a certain concentration of the fine particles; and then, the membrane filtration is repeated with a circulation membrane filtration by a cross-flow method so as to purify the fine particles. At this time, by monitoring pH of the permeated solution, progress of removal process of the ionic impurities can be readily confirmed, thereby with this it is considered that a high dispersion is obtained. However, because there is no mechanism installed to disperse or crush the aggregate, even if purification to a target pH is performed, it is difficult to remove the impurities included in the aggregate; and thus, it has been difficult to obtain a fine particle dispersion solution whose dispersion property is controlled.
Alternatively, as illustrated in Patent Literature 4, it is presumed that to stir the fine particle dispersion solution before treatment thereof with filtration membrane may be effective; however, it is difficult to disperse the aggregate of the fine particles to primary particles by mere stirring. Further, in the paragraph 0159 (Example 12) of Patent Literature 5, it is described that a disperser (BATCH SAND, manufactured by Kanpe Co., Ltd.) was used before the treatment with filtration membrane; however, this method is applied only to production of the dispersion solution of zirconia from the powders thereof. Moreover, this disperser is for rough dispersion and is used in a batch system; therefore, it is difficult to continuously disperse this with filtration membrane. It is also described that washing is carried out until conductivity of the dispersion solution reaches preferably 3 mS/cm or less, while more preferably 0.3 mS/cm or less, indicating that this is rough washing. Accordingly, the inventions disclosed in Patent Literatures 4 and 5 propose neither the technology focusing on the origin of the impurities in the fine particle dispersion solution nor the removal process of the impurities before re-aggregation. Therefore, the inventions disclosed in these literatures proposed neither to reduce total amount of the impurities in the dispersion solution including the fine particles nor to enhance dispersion property of the fine particles after completion of the treatment.

Precise modifying method for fine particle dispersion liquid


The invention relates to the development of in vitro assay systems that force the release of a water-soluble polymer, such as polyethylene glycol (PEG) and polysialic acid (PSA), from proteins modified with a reversibly-linked water-soluble polymer. The invention includes methods for analyzing the release of the water-soluble polymer and measuring regained protein activity. The invention further includes methods appropriate for the quality control of proteins modified with releasable water-soluble polymers, including polymers like PEG and PSA.

The lack or dysfunction of blood clotting Factor VIII (FVIII) is associated with the bleeding disorder hemophilia A. The treatment of choice for the management of hemophilia A is replacement therapy with plasma-derived or recombinant FVIII (rFVIII) concentrates. It is generally accepted that patients with severe hemophilia A, i.e. with FVIII levels below 1%, are best treated by a prophylactic therapy with the aim of keeping FVIII levels above 1% in-between doses. Taking into account the average half-lives of the various FVIII products in the circulation, this circulating concentration can usually be achieved by administering FVIII two to three times a week. To increase the convenience of current prophylaxis therapy, the development of a next generation product with enhanced pharmacodynamic and pharmacokinetic properties, while maintaining all other product characteristics, is envisaged to allow dosing on a weekly basis.
Therapeutic polypeptide drugs are not only exposed to proteolytic enzymes and neutralizing antibodies, but are also prone to removal from the circulation by receptor-mediated cellular uptake. These events are associated with a reduction in the half-life and circulation time of the applied proteins, thereby limiting their therapeutic effectiveness. Modification of the polypeptide drugs with polymers such as PEG has been shown to protect them from enzymatic degradation and clearance to a significant extent thereby improving their pharmacodynamic and pharmacokinetic profiles. In addition, PEGylation can lead to decreased immunogenicity, increased physical and thermal stability, increased solubility, increased liquid stability, and reduced aggregation.
PEGylation is usually achieved by the covalent attachment of one or more PEG chains per monomer to a polypeptide drug. Stable linkage of PEG to proteins has the disadvantage of decreasing the protein's biological function in an irreversible manner. This can be circumvented by modifying the proteins with a reversibly-linked PEG, which has the potential to dissociate from the protein over time. This type of releasable PEG should allow liberation of the native protein, accompanied with a full regain of the native protein's activity.

Methods for determining active ingredients in pro-drug PEG protein conjugates with releasable PEG reagents (in vitro de-pegylation)


A device for dispensing adhesive on a substrate comprises a writing head with a first dispensing nozzle and at least one second dispensing nozzle. The device can be operated in two operating modes and is configured to perform the following steps for the change from the one operating mode to the other operating mode: —lifting of the writing head, retracting or extending a pin, and lowering of the writing head to a predetermined working altitude, wherein the tips of the dispensing nozzles reach a substantially similar altitude above the substrate in the retracted state of the pin, and wherein the tip of the at least one second dispensing nozzle reaches a higher altitude above the substrate than the tip of the first dispensing nozzle in the extended state of the pin.

Such devices are used as a dispensing station in a semiconductor mounting apparatus in order to apply adhesive such as epoxy to the chip mounting surfaces of a substrate. Subsequently, the substrates are transported to a bonding station where the semiconductor chips are placed. From U.S. Pat. No. 6,129,040 and EP 1432013 devices for the application of adhesive to a substrate are known, which contain a writing head with a dispensing nozzle which is movable in three spatial directions X, Y and Z. From CH 705475 a method is known which uses a camera for recognizing the position of the substrate location prior to the application of the adhesive and for the quality control after the application of the adhesive, which coordinates the application of the adhesive with the movement of the writing head in order to obtain high throughput. From US 2003044534 a device is known which comprises a writing head with a dispensing nozzle with two outlet openings. From U.S. Pat. No. 7,977,231 a device is known which comprises two dispensing nozzles which are independently movable from each other in at least one direction. Furthermore, semiconductor mounting apparatus are known which contain two complete dispensing stations with one dispensing nozzle each.
Dispensing stations with only one dispensing nozzle come with the disadvantage that they are often slower than the following bonding station, because the waiting time which is required until the adhesive applied to the substrate has detached from the dispensing nozzle limits the throughput. The dispensing stations known from the state of the art with two dispensing nozzles come with various disadvantages, namely lack of flexibility and/or high constructional complexity.

Device for dispensing adhesive on a substrate


A new apricot tree cultivar producing early maturing fruit of very good dessert and canning qualities.

This invention relates to a new and distinct cultivar of apricot tree, developed near Cream Ridge, N.J., as part of an extensive program to develop improved apricot trees having early maturing fruit of excellent dessert and canning quality.
The cultivar of this inventiton is a seedling whose parentage is known, and was selected from a block planted near Cream Ridge, N.J., in a cultivated area of other trees whose breeding records are also kept.
The new cultivar which I have chosen to designate as NJA54, was produced by crossing a seedling known as NJA2, being the seed parent, and another selection, RR17-62, being the pollen parent.
I have found during continued growth of the trees of this cultivar, that it produces a vigorous, upright tree with fruit of excellent dessert and canning quality.
The tree flowers at about the same time as the cultivar known as "Harcot" (unpatented), and the apricot fruit produced has excellent quality with a firm texture.
During the course of the several years of observing the growth it is noted that I have caused the selection to be asexually propagated by grafting on peach rootstocks at Cream Ridge, N.J.
The selected tree was of grafted material which has maintained the desired characteristics after propagation in successive generations.


A distributed computing system provides a data management system in communication with a software management system and enables the software applications to move to the data to be processed in a distributed computing environment. The software management system stores a plurality of computer-executable software applications thereon and is in communication with a user system for receiving a selection of one of the plurality of software applications. The software management system generates an identifier for the selected software application which is provided to the data management system, which then obtains the selected software application from the software management system based on the identifier. The obtained software application is then executed with data from a data storage system using resources from a resource system. The resource system includes a plurality of resources and a manage mechanism for managing assignment of the plurality of resources to support execution of the software application.

Distributing computing environments, in which various components may be remotely located from each other, are designed around software applications that process data. In such an environment, the software applications in the system may be stored in a central location and data that is to be processed moves from a data store to the central location of the software applications. Since such a system is designed around the methods performed by the software applications, it is considered to be method-centric. A user of the distributed computing environment interacts more directly with the software applications than with the data. The data to be processed is remotely retrieved so that the data moves to where the software applications are located.
The distributed computing environment in which the data moves to the software applications operates well if the data that is moving is small. However, when the data is large, remote retrieval of the data can be a tedious process that can consume large amounts of resources for the transfer. When the data is retrieved, it is only a copy of the data that is sent. If multiple copies of the data are provided to multiple sources for processing and the data is altered during processing, then the integrity of the data becomes difficult to manage. Further, during the transfer of data to the location of the software applications the security of the data is reduced, thus introducing the possibility of corruption, theft, etc., and the possibility of non-compliance with statutory requirements for personal privacy protection.

International Business Machines Corporation


A high chair incorporates a swivel feature and a height adjustment feature that permits the seat member to be positioned to the convenience of the caregiver. The high chair includes an H-shaped base member having a vertical pedestal member that houses a gas cylinder that provides height adjustment for the seat member and that supports the seat member for rotational movement relative to the pedestal. The H-shaped base allows the high chair to be positioned close to the caregiver. A swivel lock includes an actuation lever that has handles positioned on opposing sides of the seat member for actuation from either side of the high chair. The pivoted actuation lever also includes a spring-loaded stop member that is engagable with a toothed gear plate affixed to the pedestal to secure the rotated position of the seat member by positioning the stop member between teeth on the gear plate.

Different products are used by parents to aid in the positioning of their children to facilitate feeding them from the time the child is an infant until the child is old enough and large enough to sit at a table properly. One such product is a high chair, which is typically used to support infants and small toddlers at an elevated position so that the caregiver can easily feed the child. Another such product is a booster seat that is typically attached in a detachable manner to a standard chair so that the child is elevated on the chair to reach a normal table. Booster seats are typically used with older toddlers.
The high chair is a self-standing unit that provides a safe and secure seating area with a feeding tray that is removable from the high chair to facilitate the placement of the child on the high chair and to facilitate the cleaning of the tray and high chair structure. High chairs can incorporate height adjustment mechanism so that the seat can be vertically positioned to fit various table heights so that the tray mechanism could be removed from the high chair and the child positioned on the high chair be pushed up to a table. The booster seats typically attach to the standard chair with one or two adjustable straps so that the booster seat can be removed when no longer in use. The typical booster seat positions the child about three or four inches above the chair seat to locate the child at the table. Some booster seats are provided with height adjustment to fit various table heights. Some booster seats are adapted to receive a tray mechanism so that the booster seat can be utilized away from the table.
Although office chairs and other similar devices have long incorporated a swivel feature and/or a tilt feature combined with a height adjustment feature, child high chairs have traditionally been manufactured as a fixed structure with a base on which is mounted a fixed chair member for the seating of the child with the tray selectively positionable in front of the child. An example of an office chair having a chair tilt mechanism combined with a height adjustment feature can be found in U.S. Pat. No. 5,244,253, granted to Geoffrey Hollington, et al on Sep. 14, 1993, in which the rotatably mounted office chair incorporates a gas spring in a pedestal structure for the seat base with an actuation lever that is operable to release the gas spring to permit expansion thereof and a resulting vertical movement of the seat member.
The use of gas springs in a pedestal structure to provide a height adjustment feature is not limited to office furniture. In U.S. Pat. No. 7,185,949, granted to Rebecca Finell on Mar. 6, 2007, incorporates a wheeled base formed into an upwardly extending pedestal structure within which is supported a gas spring that is connected to the seat member. A vertical height adjustment of the seat member is accomplished through the manipulation of a foot pedal that releases the gas spring in a conventional manner to permit the vertical movement of the high chair seat. This high chair structure does not incorporate a swivel feature for the seat member as rotational movement of the high chair can be accomplished through a rotation of the wheeled base, which incorporates an arresting feature to limit the movement of the wheeled base structure.
Chairs or seats are known to incorporate a swivel feature. A swivel seat for use in a vehicle, such as a farm tractor or a combine, for example, is disclosed in U.S. Pat. No. 5,482,354, issued on Jan. 9, 1996, to Dennis Gryp in which the selected rotated position of the seat is controlled through a rack mechanism that is cooperable with an actuation lever to secure the position of the seat by engaging a notch in the toothed rack with the actuation lever. Similarly, the tractor seat in U.S. Pat. No. 5,733,006, issued to Perry Woods on Mar. 31, 1998, is positionally controlled by a stop pin engagable through aligned holes in the seat member and the base member, with the actuation mechanism being positionable in a free swivel mode of operation.
In U.S. Pat. No. 6,361,111, granted on Mar. 26, 2002, to Daniel Bowers, et al, the seat member of a powered personal mobility vehicle is pivotally mounted for movement through substantially a 180 degree range of movement to permit the operator to rotate the seat member ninety degrees from a central operating position for ease of ingress and egress to the seat member. This seat member incorporates a notched disk affixed to the base member. The actuation lever can be pivotally manipulated to selectively place a stop member into engagement with the notched disk to secure the seat member in the selected rotated position.
The high chair disclosed in U.S. Pat. No. 7,032,966, granted to Peter Myers on Apr. 25, 2006, includes a base stand that can incorporate a turn table mechanism that provides a rotational function for the high chair seat member. The turn table mechanism incorporates a series of notches around the circumference thereof. A spring-loaded latch mechanism is engagable with the notches around the circumference of the turn table mechanism to restrain the rotated position of the high chair seat member. As is seen in FIGS. 11-16 of the Myers patent, the turn table mechanism is a substantial structural part of the seat member that also incorporates a tilt function for the seat member.
It would be desirable to provide a high chair structure that will provide a swivel feature that can be actuated conveniently by the caregiver to position the high chair seat member at a desired rotated position relative to the base member, while incorporating a high adjustment feature for the seat member.

High chair with swivel feature and height adjustment


This system and method provides a direction finding system that enables modern RF DF systems to analyze short duration signals in the entire instantaneous bandwidth. By providing a method to process wideband data, the invention drastically improves throughput and probability of intercept (POI). The invention is unique in that it does not require separate narrowband channels for analysis, and can simultaneously calculate azimuth and elevation estimates for every frequency in the bandwidth of an incident signal. It is also well-suited for fixed point, FPGA implementations making it a perfect match for modern state-of-the-art processing systems. The system and method capitalizes on the ability of Fourier Frequency Transform operations to accurately resolve incident wave phase at discrete frequencies. The system then uses the phase information from the individual elements in the array to arrive at an emitter azimuth angle. The azimuth angle is nearly simultaneously used in concert with lookup tables of all possible elevation angles to compare the arrival time delay between the array elements to determine emitter elevation angle.

1. Field of the Invention
This invention relates generally to signal transmitter locating systems and, more specifically, to a Method for Real-time, Automatic, Wideband, High Accuracy 3D RF Direction Finding.
2. Description of Related Art
This patent application describes an enhanced method for locating radio frequency signal emitters.
Today's high frequency direction finding systems perform well in situations that require analysis on very few frequencies and when target signals are of constant frequency and long duration. However, these systems suffer from serious performance and cost issues in the face of short duration signals or situations that require analysis of the entire RF band. A modern RF DF system should process entire receiver bandwidths at speeds that enable it to analyze modern, short duration signals without introducing enormous hardware requirements and costs.
Current Direction Finding systems are narrow-band in nature, possessing bandwidths of a few Kilohertz (KHz) and requiring many RF receiver channels and DSP processors to digitize and process each narrowband channel. The results are then later stitched together. This approach is very costly for the subset of real-world applications, often referred to as wideband applications, which require the analysis of large segments of the Electromagnetic Spectrum. Generally, to keep costs down, fewer receiver channels are used which adversely effects processing efficiency as the system can only process small amounts of bandwidth simultaneously. In addition, further serial processing is required if elevation and azimuth are desired compounding both cost and efficiency problems.
What is needed therefore, in order to feasibly determine the angle of arrival (AoA) of RF emitters as efficiently as possible is a method that not only (1) operates on wideband data provided by a single receiver channel doing work that would normally require thousands of separate receivers, but also (2) calculates both azimuth and elevation results at numerous frequencies in parallel. Multipath results in errors in the determination of the arrival angles. By increasing the size of the antenna array so its diameter is larger than the wavelength substantial reduction of the multipath errors can be achieved. When the array diameter is larger than half the wavelength then special methods have to be applied in order to remove the ambiguities in the received relative phases. This patent application describes such a method.

Method for real-time, automatic, wideband, high accuracy RF direction finding


An ultrasonic diagnostic imaging system has a thin two dimensional array transducer probe which is taped or belted to a patient to image a target region during radiotherapy. The radiotherapy procedure is conducted based upon planning done based on images of the target region acquired prior to the procedure. The array transducer is operated by an ultrasound system to produce three dimensional images of the target region by electronic beam steering, either during or between fractions of the treatment procedure. The ultrasound images are used to adjust the treatment plan in response to any movement or displacement of the target anatomy during the treatment procedure.

In preparation for radiation therapy or radiotherapy, medical diagnostic images are taken of the treatment target (tumor) to plan the procedure. Both the location (depth) of the tumor and the presence of surrounding healthy tissue structures are taken into consideration in planning the procedure. These considerations lead to a choice of the intensity and focus of the radiation dose, the locations in the tumor where treatment fractions are to be delivered, and the path of the radiation beam through surrounding healthy tissue. Typically the planning images are CT images of the target region, called a simulation CT scan. Based on the CT images, the outcome of the planning is a set of instructions that are sent to the treatment d delivery device, usually a linear accelerator. The instructions define the path of radiation delivery and the planned dose distribution inside the patient. Since the planning images are acquired prior to commencement of the treatment, it is of paramount importance that the treatment target (the tumor) and the surrounding structures (healthy tissues) are positioned exactly as they appear in the simulation CT scan before each treatment fraction; otherwise the dose will not be safely and correctly delivered. Patient positioning is therefore becoming increasingly of interest in order to obtain the desired results of treatment.
One of the modalities which can be used in image guidance of radiotherapy is ultrasound imaging, which has some unique characteristics. Ultrasound has been widely used for diagnosis of cancer. It is relatively inexpensive and easy to use and, with ever-increasing improvements in image quality, it can have a diagnostic value comparable to MRI or CT imaging. Two dimensional (2D) ultrasound images of the target are compared to the corresponding CT projections conventionally used for radiotherapy planning. Similar to MRI, ultrasound imaging is benign and does not add extra undesirable radiation dose to the patient, and it is generally a non-invasive imaging modality. Ultrasound imaging is therefore a good candidate for organ motion monitoring between treatment fractions, which is a prerequisite for adaptive applications.
The initial use of ultrasound in radiotherapy followed the typical use of ultrasonic multiplanar reconstruction to visualize two perpendicular planes of the target. This first application of ultrasound was available only for prostate cancer treatment and showed many limitations, which have been documented in the literature. See Langen et al., "Evaluation of ultrasound-based prostate localization for image-guided radiotherapy," Int. J. Radiat. Oncol. Biol. Physics, vol. 57 (2003) at pp 635-44; and Van den Heuvel et al., "Independent verification of ultrasound based image-guided radiation treatment, using electronic portal imaging and implanted gold markers," Med. Phys., vol. 30 (2003) at pp 2878-87. At the present time, only prostate cancer treatment has been clinically implemented using a mechanically swept transducer which continuously scans the target trans-perineally during irradiation. The position of the prostate is compared to the position of the prostate in a trans-perineal ultrasound image acquired prior to commencement of the procedure which is used for the therapy planning. During setup of the patient for each treatment fraction, ultrasound guidance determines the position of the targets and nearby organs at risk. The current position of the target can be used to recalculate dose and, if necessary, re-plan the patient treatment in adaptive applications. See Abramowitz et. al., "Noninvasive Real-time Prostate Tracking Using a Transperineal Ultrasound Approach", In'l J. Rad., Oncol., Biol. & Physics, vol.84 (2012) at pp S133, and Court et al., "Automatic online adaptive radiation therapy techniques for targets with significant shape change: a feasibility study," Phys. Med. Biol., vol. 51 (2006) at pp 2493-50.
One of the problems inherent in the application of ultrasound for radiation therapy guidance is the need to maintain good acoustic coupling of the ultrasound probe to the body of the patient. Typical ultrasound probes have handles which are grasped by the clinician and used both to hold the probe and to press it into good acoustic contact with the skin of the patient. The problem this causes in radiotherapy is displacement of the tumor and adjacent and intervening tissues and organs by reason of the firm pressure needed to press the probe against the patient. Thus, the use of ultrasound itself becomes a source of re-positioning of the anatomy of the patient from that which is shown in the planning images, requiring treatment re-planning and reprogramming of the therapy delivery system as a result. Accordingly it is desirable to be able to use ultrasound for radiotherapy image guidance, but in a way which does not disrupt the constant positioning of organs and tissues necessary for a safe and effective radiotherapy procedure.

Ultrasonic image guidance of radiation therapy procedures


Compositions and methods are provided for treatment of autoimmune and other related diseases. 3d, a point mutation of the protein uncoordinated-93b (unc-93B), unc-93A, unc-93B, and unc-93C, polypeptides, nucleic acids encoding them and methods for making and using them, for example, to produce transgenic non-human animals.

The mammalian Toll-like receptors (TLR) sense conserved molecules of microbial origin, including bacterial lipopolysaccharides (LPS), lipopeptides, glucans, flagellin, and nucleic acids. Poltorak, A. et al., Science 282:2085-2088, 1998; Takeuchi, O. et al., J. Immunol. 164:554-557, 2000; Takeuchi, O. et al., 13:933-940, 2001; Gantner, B. N. et al., J. Exp. Med. 197:1107-1117, 2003; Hayashi, F. et al., Nature 410:1099-1103, 2001; Hemmi, H. et al., Nature 408:740-745, 2000; Alexopoulou, L. et al., Nature 413:732-738, 2001; Diebold, S. S. et al., Science 303:1529-1531, 2004; Heil, F. et al., Science 303:1526-1529, 2004; Lund, J. M. et al., Proc. Natl. Acad. Sci U.S.A 101:5598-5603, 2004. While TLRs 1, 2, 4, and 6 are at least partly represented on the surface of mammalian cells, TLRs 3, 7, and 9, which detect dsRNA, ssRNA, and unmethylated DNA, respectively are predominantly or entirely intracellular receptors, residing within the endoplasmic reticulum (ER) and/or endosomes. Hemmi, H. et al., Nature 408:740-745, 2000; Alexopoulou, L. et al., Nature 413:732-738, 2001; Diebold, S. S. et al., Science 303:1529-1531, 2004; Heil, F. et al., Science 303:1526-1529, 2004; Lund, J. M. et al., Proc. Natl. Acad. Sci U.S.A 101:5598-5603, 2004; Matsumoto, M. et al., J. Immunol. 171:3154-3162, 2003; Funami, K. et al., Int. Immunol. 16:1143-1154, 2004; Ahmad-Nejad, P. et al., Eur. J. Immunol. 32:1958-1968, 2002; Leifer, C. A. et al., 173:1179-1183, 2004; Latz, E. et al., 5:190-198, 2004; Heil, F. et al., Eur. J. Immunol. 33:2987-2997, 2003.
TLRs mediate the great majority of phenomena associated with microbial infections, including the upregulation of costimulatory molecules that are required to initiate adaptive immune responses to peptides processed and presented by antigen-presenting cells of the host. Beutler, B. Nature 430:257-263, 2004. But the processing and presentation of antigens—whether endogenous or exogenous—occurs constitutively in the absence of infection and does not dependent upon TLR signaling. Moreover, where exogenous antigens are concerned, processing for class I MHC presentation (cross presentation) involves a series of biochemical events very different from those associated with processing for class II MHC presentation.

Compositions and methods for treatment of autoimmune and related diseases


The present invention provides an induction-hardened hollow driving shaft that comprises, as a raw material, a steel pipe that contains, by mass %, 0.30 to 0.47% C, 0.5% or less Si, 0.3 to 2.0% Mn, 0.018% or less P, 0.015% or less S, 0.15 to 1.0% Cr, 0.001 to 0.05% Al, 0.005 to 0.05% Ti, 0.004% or less Ca, 0.01% or less N, 0.0005 to 0.005% B and 0.0050% or less O (oxygen) and the balance Fe and impurities and of which Beff defined by an equation (a) or (b) below is 0.0001 or more, wherein a prior austenite grain size number (JIS G0551) after the hardening is 9 or more. Here, in the case of Neff=N−14×Ti/47.9≧0, Beff=B−10.8×(N−14×Ti/47.9)/14 . . . (a), and, in other cases, Beff=B . . . (b). According to the present invention, a hollow driving shaft that is simultaneously provided with excellent cold workability, hardenability, toughness and torsional fatigue strength and can exert stable fatigue lifetime can be obtained and can be widely utilized.

1. Field of the Invention
The present invention relates to an induction hardened hollow driving shaft suitable for reducing weight of a driving shaft that transmits an engine diving force of an automobile to respective wheels such as a drive shaft, in more detail, an induction hardened hollow driving shaft excellent in cold workability, hardenability, toughness and torsional fatigue strength that are demanded as fundamental characteristics of the driving shaft.
2. Description of the Related Art
Of automobile parts, in a drive shaft that is used as a driving shaft that transmits an engine driving force to wheels, as an automobile engine becomes higher in its output, a demand for higher strength is stronger. Normally, as the strength characteristics necessary for the drive shaft, the torsional fatigue strength is cited. Accordingly, hitherto, with a drive shaft having a solid structure, a drive shaft that exerts excellent torsional fatigue strength characteristics and steel that is used therefor have been proposed.
Although the deeper a depth of a hardened layer is, the more the fatigue strength of the driving shaft is improved, when the hardened layer is made excessively deep, there is a risk of quench crack. Accordingly, in Japanese Patent Application Publication No. 2000-154819, proposed is a high strength drive shaft where, in order to obtain a high strength drive shaft, an upper limit of a depth of the hardened layer is defined, and, in order to secure the hardness of the hardened layer, higher C and lower Cr are aimed in a composition design.
In the torsional fatigue fracture of an induction hardened member, since a crack occurs in a plane in parallel with a longitudinal direction of the shaft and at a boundary between a surface or a hardened layer and a core portion and initially propagates in a plane in parallel with the longitudinal direction, when elongated MnS is present in the longitudinal direction, along the elongated MnS, an occurrence and the initial propagation of the crack are promoted. Accordingly, Japanese Patent Application Publication No. 2002-69566 has proposed induction hardening steel where MnS is granulated and made finer. Thereby, the crack is inhibited from occurring and initiating the propagation and thereby the torsional fatigue strength can be improved.
The high strength drive shaft and the induction hardening steel proposed in the Japanese Patent Application Publication Nos. 2000-154819 and 2002-69566 are applied as a method of improving the torsional fatigue strength of a driving shaft that postulates a solid structure and expected to exhibit predetermined strength characteristics.
However, from a viewpoint of a recent further global environmental protection, it is strongly demanded to make an automobile body lighter to improve the fuel efficiency. Accordingly, there has been variously attempted to replace, in automobile parts, solid members with hollow members. As one of the attempts, as a driving shaft, a hollow structure is under study to adopt. When an automobile part is made a hollow structure, not only simple lightweight, but also an improvement in acceleration response owing to an improvement in the torsional stiffness and an improvement in the quietness in a running car owing to an improvement in the vibration characteristics can be expected.
In order to achieve such expectations, a development of a hollow driving shaft fabricated into a special shape is strongly demanded. For instance, in a design of a shaft that engages both shaft end portions with constant-velocity joints, while an intermediate portion of a driving shaft is made as small as possible in the thickness and as large as possible in the diameter to heighten the torsional stiffness and improve the vibration characteristics, the both shaft end portions that engage with the constant-velocity joints are made with a diameter same as that of the solid member used thus far, and thereby an existing constant-velocity joint can be favorably used as it is.
As a manufacturing method of a hollow driving shaft, there is a method where to both end portions of a hollow blank tube hollow or solid shafts are engaged by use of a friction welding method. However, in the method, it is difficult to make a diameter of the hollow portion larger and that of the both end portions smaller. From the above reason, in order to form a driving shaft having a shape where an intermediate portion is made as small in the thickness and as large in the diameter as possible and diameters of the both end portions are made small, a steel pipe material is cold worked to make the intermediate portion thinner in the thickness, followed by applying cold reducing process etc. to both ends of the steel pipe material to reduce outer diameters of the both end portions to thicken the wall thickness thereof, and thereby an integrally formed hollow driving shaft is manufactured.
In the integrally formed hollow driving shaft, in order to secure a special shape thereof, a complicated cold working is applied to form. Accordingly, in order to do so without the occurrence of the crack caused during the cold working and to secure the torsional fatigue strength after the working, as a raw material of an integrally formed hollow driving shaft, for instance, a seamless steel pipe is necessarily adopted.
When an integrally formed hollow driving shaft is manufactured with a steel pipe as a hollow shaft material, it is important to inhibit the crack due to the reducing process or spinning process at the pipe end from occurring. Furthermore, it is demanded that after the cold working, the heat treatment is applied to harden over an entire thickness of the steel pipe from an outer surface to an inner surface to secure high toughness and furthermore to secure the torsional fatigue strength so as to enable to obtain long lifetime as a product.
In other words, in the hollow driving shaft of which raw material is a steel pipe, it is indispensable to satisfy the cold workability that enables to easily obtain a complicated shape, the hardenability accompanying the heat treatment, and the toughness and torsional fatigue strength, and to achieve stable fatigue lifetime as the driving shaft. However, in the hollow driving shafts hitherto proposed, studies from the viewpoints of materials or the grain boundary strength have hardly done.
For instance, in Japanese Patent Application Publication No. 6-341422, a drive shaft where a balance weight is attached to a driving shaft steel pipe to reduce the rotational whirling is disclosed, and it is further disclosed that, when values of carbon equivalents (Ceq=C+Si/24+Mn/6+Cr/5+Mo/4+Ni/40+V/14) of the driving shaft steel pipe and the balance weight are defined, the fatigue fracture generated from a site where the balance weight is welded can be reduced.
However, when only values of carbon equivalents (Ceq) of the driving shaft steel pipe and the balance weight are defined, the driving shaft steel pipe excellent in both the cold workability and the fatigue characteristics cannot be obtained. Accordingly, it is difficult to apply an automobile drive shaft disclosed in the Japanese Patent Application Publication No. 2000-154819 as an integrally formed hollow driving shaft.
In the next place, in Japanese Patent Application Publication No. 7-18330, a manufacturing method of high strength and high toughness steel pipe suitable for a high strength member used in automobile underbody members is proposed. In the manufacturing method according to the disclosure, a specific composition system is defined. However, since neither Ti is added nor N is defined, even when B is added, it is not a composition system that can secure sufficient hardenability. Furthermore, since neither the cold workability nor the fatigue characteristics is considered in the composition design, in the manufacturing method proposed in Japanese Patent Application Publication No. 7-18330, it is difficult to obtain an integrally formed hollow driving shaft.
On the other hand, Japanese Patent Application Publication No. 2000-204432 discloses a drive shaft where the induction hardening is applied to graphite steel to harden a superficial layer and to generate two-phase structure of ferrite and martensite at a core portion. However, a chemical composition that the Japanese Patent Application Publication No. 2000-204432 discloses shows a composition system suitable for a hollow driving shaft steel material for use in the friction welding and it takes a long heat treatment time to obtain graphitized steel. Furthermore, since the chemical composition does not include Cr and the hardenability and the fatigue strength are insufficient, an integrally formed driving shaft cannot be obtained.
In Japanese Patent Application Publication No. 2001-355047, as a raw material of a drive shaft, a high carbon steel pipe that has a grain diameter of cementite of 1 μm or less and is excellent in the cold workability and the induction hardenability is proposed. However, in the high carbon steel pipe proposed in Japanese Patent Application Publication No. 2001-355047, since the warm working is necessary to obtain a target microstructure, the manufacturing cost goes up. At the same time, the disclosed steel composition cannot constitute an integrally formed hollow driving shaft simultaneously satisfying the cold workability, the hardenability and the fatigue characteristics.
In order to not only simply achieve lightweight but also achieve an improvement in acceleration response owing to an improvement in the torsional stiffness and in the quietness in a running car room owing to an improvement in the vibration characteristics, a development of hollow driving shaft is necessary. When a solid driving shaft is manufactured, as the heat treatment, the surface hardening is applied. On the other hand, when a hollow driving shaft is manufactured, in order to secure sufficient strength, it is necessary to apply the hardening over an entire thickness to an inner surface of the driving shaft.
As described in Japanese Patent Application Publication No. 2002-69566, in the torsional fatigue fracture in the solid diving shaft, a crack is generated in a plane in parallel with the longitudinal direction at a boundary between a surface or a hardened layer and a core portion. On the contrary, according a study by the present inventors, the torsional fatigue fracture in the hollow diving shaft is generated in a direction that is at 45° to the longitudinal direction, and in a principal stress plane. This is because while in the solid driving shaft a deformation energy that accompanies load of the torsional torque is absorbed by a low hardness region inside of the solid driving shaft, in the hollow driving shaft such an action of absorption of the deformation energy is not generated.
According to a further study of the present inventors, in the hollow driving shaft, owing to the load of the torsional torque, the intergranular fracture tends to occur. In particular, when the intergranular fracture occurs at an early stage, the torsional fatigue fracture rapidly progresses and the fatigue lifetime of the driving shaft becomes obviously instable. The instability of the fatigue lifetime as well is assumingly caused by the fact that in the hollow driving shaft the deformation energy accompanying the torsional torque is not absorbed in a low hardness region inside of the shaft.
Thus, in the hollow driving shaft and the solid driving shaft, owing to difference of the hardened microstructures due to the heat treatment, fracture behaviors under torsional torque load are different. Accordingly, in order to improve the torsional fatigue fracture of the hollow driving shaft and to stabilize the fatigue lifetime thereof, improvement methods of the torsional fatigue strength proposed in Japanese Patent Application Publication Nos. 2000-154819 and 2002-69566 cannot be applied. That is, in the hollow driving shaft, since owing to the load of the torsional torque the intergranular fracture tends to occur, in order to improve the torsional fatigue fracture of the hollow driving shaft and to stabilize the fatigue lifetime thereof, the strength of a prior austenite grain boundary is necessarily secured.
On the other hand, when a steel pipe is used as a raw material of the hollow driving shaft, it is necessary that the crack due to the reducing process or spinning process at the pipe end is inhibited from occurring, the heat treatment is applied after the cold working to harden an entire thickness through an inner surface of the steel pipe and to secure high toughness, and furthermore in order to display excellent performance as the hollow driving shaft, the cold workability, the hardenability, the toughness and the torsional fatigue strength are simultaneously secured.
However, in proposals of Japanese Patent Application Publication Nos. 6-341422, 7-18330, 2000-204432 and 2001-355047, there is hardly found an attempt where so as to exhibit, as a hollow driving shaft with a steel pipe as a raw material, excellent cold workability, the hardenability, the toughness and the torsional fatigue strength, raw materials and grain boundary strength are studied and thereby the chemical composition and grain diameter are specified.
In other words, each of the characteristics that the hollow driving shaft demands is not difficult to improve individually. However, according to existing knowledge, it is considered difficult to simultaneously satisfy all the characteristics. For instance, since, in order to secure high fatigue strength, the strength of the steel is effectively increased, when the steel pipe that is used as a raw material is made high in the strength, whereby the cold workability is deteriorated accordingly.


A method of using a GPS receiver to receive secondary data. A conventional GPS receiver is modified to receive such data, without modifying its hardware. The secondary data is carried in a signal that has the same characteristics as a conventional GPS navigation signal, but is delivered at a specified frequency and time and with a specified and “unused” spreading code. The secondary data is contained in a data subframe that is sufficiently similar to subframes that carry GPS navigation data, such that it can be demodulated and accessed by the GPS receiver.

GPS, which stands for Global Positioning System, is a geolocation system designed to determine the position of a receiver unit on the Earth anytime, in any weather, anywhere. GPS has 3 parts: the space segment, the user segment, and the control segment. The space segment consists of at least 24 satellites, each in its own orbit above the Earth. The user segment consists of small receivers. The control segment consists of ground stations (five of them, located around the world) that make sure the satellites are working properly.
The GPS satellites each take 12 hours to orbit the Earth. Each satellite is equipped with an accurate clock to let it broadcast signals coupled with a precise time message. A receiver receives the satellite signal, which travels at the speed of light. Even at this speed, the signal takes a measurable amount of time to reach the receiver. The difference between the time the signal is sent and the time it is received, multiplied by the speed of light, enables the receiver to calculate the distance to the satellite. To measure precise latitude, longitude, and altitude, the receiver measures the time it took for the signals from four separate satellites to get to the receiver.
GPS receivers can be hand carried or installed on aircraft, ships, tanks, submarines, cars, and trucks. Many different receiver models are in use. The typical hand-held receiver is about the size of a cellular telephone, and newer models are even smaller.
The GPS signals to a GPS receiver are fairly weak, and significant amounts of processing power are required to acquire and track them. When the receiver is indoors, the signals are considerably attenuated by structure such as walls and ceilings, and the signal strengths may easily drop below the receiver's sensitivity level. As a result, current GPS receivers do not work indoors and often fail or experience severe accuracy degradation in urban environments or under dense foliage.
Various approaches have been developed to increase the sensitivity of GPS receivers so that they may be used indoors. "Assisting data", such as techniques for weak signal detection, along with efficient correlation and synchronization algorithms, may be delivered to the receiver. One approach, used for cellular handsets that include a GPS receiver as well as the cellular signal receiver, is to pass assisting data from a cell site to the handset via the cellular system. The data is then passed to the GPS receiver. A second approach is the use of differential GPS (psuedolite system), which broadcasts correction data to GPS receivers. A third approach uses a wide area augmentation system (WAAS), specifically for aiding aircraft during landing. Each of these systems requires receiver hardware in addition to that used for acquiring and processing navigation data.

Method for delivering secondary (non-location) data to a GPS receiver


A portable exercising apparatus includes a chest-expander, two rod members adapted for fastening to two handles at two distal ends of the chest-expander for vertical pulling exercises, two wheels adapted for mounting on one rod member for back and forth body extending exercises on the floor, and a bag adapted for holding parts of the exercising apparatus when the exercising apparatus is not in use or fastening to the other handle of the chest-expander to hold a pad to support the knees on the floor when performing back and forth body extending exercises.

The present invention relates to exercising apparatus, and more particularly to a portable exercising apparatus that can be detached and then received in a carrying bag when not in use.
A variety of handy exercising apparatus, including chest-expander, hand-muscle developer, etc., have been disclosed, and have appeared on the market. FIG. 1 shows a conventional chest-expander for developing the muscles of the chest. This structure of chest-developer 8 is generally comprised of two handles 81, and a plurality of elastic cord members 80 connected between the handles 81. This structure of chest-developer is inexpensive and functional. However, exercising the body with this structure of chest-developer for a long period of time is quite boring because this structure of chest-developer provides only one single function.
According to one aspect of the present invention, a portable exercising apparatus includes a chest-expander having two handles and a plurality of elastic cord members connected between the handles, two rod members, two wheels, a bag having two barrels longitudinally aligned at one peripheral side, and a pad. When not in use, the chest-expander, one rod member, the wheels and the pad can be received in the bag, and the other rod member can be fastened to the bag on the outside to serve as a carrying handle for carrying by hand. According to another aspect of the present invention, the two rod members can be fastened to the two handles of the chest-expander for vertical pulling exercises. According to still another aspect of the present invention, the chest-expander can be separately used for exercising the muscles of the chest. According to still another aspect of the present invention, the rod members can be respectively fastened to the handles of the chest-expander to secure the bag and the wheels to the handles of the chest-expander so that the bag can be put with the pad on the floor to support the user""s knees on the floor, and the user can lay the knees on the bag on the floor and then operate the distal rod member with the hands to move the wheels back and forth on the floor.


A method of remineralizing teeth by using an oral hygiene composition comprising a polyvinyl acetal diethylaminoacetate and a fluoride ion-feeding compound; and the composition for use in the method.

The present invention relates to an oral composition effective for remineralizing teeth, and a method for using the same.
In an oral cavity, there is an equilibrium state in which a constituent ingredient of teeth, hydroxy apatite, dissolves from the teeth, and a calcium ion or a phosphate ion in a saliva deposits onto the tooth surface. Due to this equilibrium state, the tooth surface is always changing. When the equilibrium moves towards the dissolution of hydroxy apatite, a white spot develops on the tooth surface, which leads to a caries-inducing state referred to as demineralization. When the equilibrium moves towards the reformation of a demineralized enamel from hydroxy apatite, which is referred to as remineralization, caries can be prevented or treated by the remineralization.
A major factor governing the equilibrium is a saturation degree of hydroxy apatite in the oral cavity. That is, when hydroxy apatite becomes supersaturated, the remineralization occurs. Reversely, when the saturation degree of hydroxy apatite is lowered, the demineralization occurs. Since hydroxy apatite dissolves in an acid, in an acidic region, the saturation degree is lowered and the demineralization occurs.
Thus, there has been proposed an oral composition into which hydroxy apatite and calcium compounds, constituent ingredients thereof are blended and which promotes the remineralization.
For example, there is described that the remineralization is promoted by using certain hydroxy apatite in JP-A 55-57514, tetra-calcium phosphate in JP-A 1-71807, or amorphous calcium phosphate in U.S. Pat. No. 5,562,895. There is described a composition with added soluble calcium phosphate containing calcium and phosphate in the ionized state in JP-A 8-319224, and there is described a toothpaste containing silica and dicalcium phosphate in JP-A 8-502988 (WO 94/10969).
For the remineralization, it is also known that fluoride ion-feeding compounds release a fluoride ion to promote a remineralization process and, thereby, reduce caries that has previously been existed within a tooth structure. For example, there are proposed a combination of xylitol and a fluoride in U.S. Pat. No. 371,145, and a combination of hydroxy apatite and a fluoride in JP-A 1-110608. However, although a certain effect has been recognized for the primary teeth, a product which can be said to be sufficient for remineralizing the second teeth has not been developed yet.
By the way, it has been hitherto known that a fluoride ion reinforces a dentine. Thus, an attempt to enhance the caries preventing effect has been tried by intensifying such an action of a fluoride ion. In JP-A 63-246316, pyridoxine derivatives are blended into an oral composition for the purpose of promoting uptake of a fluoride ion and improving an acid-resistant property of the teeth. There is proposed a poly-cationic polymer in JP-A 3-5417. However, none of them disclose the remineralizing action.
The previous methods, which employ a composition into which hydroxy apatite is blended or an oral composition into which a fluoride is blended, can not accomplish the desired effect on the teeth under an oral cavity environment where the teeth are easily demineralized, or on the teeth which has already begun to be demineralized. Also, there is a limitation that a pH of a formulation as an oral composition is required to adjust to a higher pH than that of a weak acid because when the oral cavity is made acidic, the demineralization is caused.
An object of the present invention is to enhance the effects of preventing or treating caries of an enamel or root surface, or dentin hyperesthesia, by promoting the ability of fluorine to remineralize.
The present inventors extensively studied the promotion of the remineralizing action of a fluoride ion and, as a result, found that polyvinyl acetal diethylaminoacetate has an excellent remineralizing action promoting effect. Polyvinyl acetal diethylaminoacetate was developed as a coating agent for tablets, and, for instance, there is reported in JP-A 5-339136 that it is effective for suppressing dental plaque accumulation or promoting adsorption of a fluoride onto the tooth surface. However, its remineralizing action promoting effect is not known.
Also, the present inventors found that even when a pH of an oral composition is adjusted to an acidic region of about 3-6.5, the demineralization is not caused, and, unexpectedly, the remineralizing action promoting effect is remarkably improved than in a neutral region. Moreover, the present inventors found that the remineralizing action promoting effect is also improved by blending an anionic surfactant therein.
The present invention was completed based on such novel findings and in one aspect thereof, provides a method of remineralizing teeth which comprises using an oral composition comprising polyvinyl acetal diethylaminoacetate and a fluoride ion-feeding compound which feeds a fluoride ion. This oral composition may further contain an anionic surfactant.
In an another aspect, the present invention provides an oral composition for remineralizing the teeth, which is used for the method of the present invention.
Polyvinyl acetal diethylaminoacetate to be used in the present invention is an acetal produced by dehydration between polyvinyl alcohol and acetaldehyde, and which is a basic high-molecular compound in which a part of the remaining hydroxyl groups are bound to diethylaminoacetic acid via an ester linkage and, for example, a commercially available product such as xe2x80x9cAEAxe2x80x9d (Sankyo Corporation) may be used.
An amount of polyvinyl acetal diethylaminoacetate to be blended is in the range of 0.01-10% by weight, preferably in the range of 0.02-2% by weight, from a viewpoint of the promotion of the remineralizing action.
As the fluoride ion-feeding compound which feeds a fluoride ion, there are sodium fluoride, potassium fluoride, ammonium fluoride, calcium fluoride, copper fluoride, zinc fluoride, lithium fluoride, cesium fluoride, zirconium fluoride, tin fluoride, sodium monofluorophosphate, potassium monofluoro-phosphate, sodium titanium fluoride, potassium titanium fluoride, hexylamine hydrofluoride, laurylamine hydrofluoride, cetylamine hydrofluoride, lysine hydrofluoride, glycine hydrofluoride, alanine hydrofluoride, fluorosilane and the like, and they can be used alone or in a combination of two or more of them. In view of the oral use, preferred are sodium fluoride, potassium fluoride, ammonium fluoride, tin fluoride, sodium monofluorophosphate, and potassium monofluorophosphate. An amount of the fluoride ion-feeding compound to be blended is in the range of 10-50,000 ppm, preferably 90-20,000 ppm in terms of a fluoride ion based on the total amount of the oral composition, from a viewpoint of the remineralizing effect. When the amount is below 10 ppm, the remineralizing action can not be expected and, when it exceeds 50,000 ppm, the remineralization promoting effect by polyvinyl acetal diethylaminoacetate does not increase much, being not economical. In a method of using almost every day for a long period of time, the concentration in the composition of 90-5,000 ppm is particularly preferred and, in a method of using at long-term intervals exceeding one month, 9,000-20,000 ppm is particularly preferred.
As the anionic surfactant to be used in the present invention, there are salts of N-long chain acyl basic amino acid such as sodium salt of N-acyl-L-glutamate, sodium salt of N-hydrogenated tallow fatty acid acyl-L-glutamate, sodium lauroyl sarcosinate, water-soluble salts of higher alkyl sulfate having alkyl group of 8-18 carbon atoms such as sodium lauryl sulfate and sodium myristyl sulfate, polyoxyethylene alkyl sulfate salt, alkylsulfoacetate salt, xcex1-olefin sulfonate salt, sulfosuccinate derivatives, sodium salt of higher fatty acid monoglyceride monosulfate, N-methyl-N-palmitoyltauride salts and the like. An amount of the anionic surfactant to be blended is 0.01-10% by weight, preferably 0.1-5% by weight based on the total amount of the oral composition.
As an acid to be used for adjusting a pH of the oral composition, citric acid, malic acid, phosphoric acid, and aromatic carboxylic acids such as benzoic acid, nicotinic acid and salicylic acid, and salts thereof are exemplified, and one or more selected from them may be used. A preferred pH range is 3-6.5. When a pH is below 3, the demineralization by an acid is remarkable and, when a pH exceeds 6.5, the effect becomes weak. An amount of the acid to be blended is preferably 0.01-3% by weight and, when it exceeds 3% by weight, a physical property as an oral composition becomes unstable.
The oral composition of the present invention may be appropriately formulated, depending upon its use, into a form such as toothpaste, pasta, powder or liquid dentifrice, wetting dentifrice, gel, cream, mouthwash, spray, foam, coating agent and the like, according to the conventional methods. Other ingredients to be blended are not particularly limited and the known polishing agents, humectants, thickening agents, foaming agents, preservatives, flavoring agents, therapeutic agents and the like may be blended into the oral composition, so long as they do not deteriorate the effects of the present invention.
A container may be made of compatible materials, all kinds of dispenser-container are usable, and a laminate tube made of aluminium or plastics, a plastic container such as of squeeze-type and pump dispenser, or an aerosol container may be used. In the case of a gel or varnish form, the composition may be contained in a syringe.
The method of the present invention may be practiced by applying the oral composition to the demineralized portion of the tooth such as by brushing or mouth washing. For example, in the case of a dentifrice or a mouthwash, they are used one to three times a day according to the conventional using method. Usually, 0.2-1.5 g of a dentifrice or 5-20 ml of a mouthwash as a daily amount is used so that the daily amount of a fluoride is 0.1-2 mg, particularly preferably approximately 1 mg. Moreover, the oral composition of the present invention may be formulated into the form such as a gel or a varnish to specifically apply onto the demineralized portion of the teeth in a topical manner. In the case of a gel or a varnish for the topical application, it may be applied in the frequency of once a month to once a year.
The remineralization of teeth is accomplished by the above way of using and, thereby, the effects of preventing or treating caries, root surface caries and dentin hyperesthesia can be exerted.


Amounting apparatus used to fasten a PCB (10) with through holes (12) includes a supporting board (20) and a plurality of clips (30) mounted on the PCB. The supporting board has a plurality of standoffs (22) corresponding to the through holes of the PCB. Each of the clips includes a resilient portion (34) and defines a mounting opening (35) for having the standoffs sliding therein. When the standoffs press on the resilient portions of the clips, the PCB is clamped on the supporting board.

1. Field of the Invention
The present invention relates to mounting apparatuses for printed circuit boards (PCBs), and particularly to a mounting apparatus for a PCB of a computer or server.
2. Background of the Invention
A PCB of a computer, such as a motherboard, is usually mounted to the computer by screws as described in China Patent No. 00201452.1. A plurality of protrusions is arranged on a bottom panel of the computer. Each of the protrusions defines a hole therein. In assembly, a plurality of screws is mounted into holes defined in the PCB and the corresponding holes of the protrusions. The PCB is thus mounted in the computer. However, the mounting means described above is inefficient and cumbersome for a large number of screws are used.
Another mounting apparatus for a PCB is provided in China Patent No. 02231300.1. The mounting apparatus includes a locking member, a slide member and an elastic subassembly. The locking member defines a quadrate slot in an end portion thereof. A hook protrudes from a middle portion of the locking member. The slide member can move in one direction on a chassis of a computer and defines a positioning hole therein. The elastic subassembly is mounted between the chassis and the slide member. In assembly, the locking member is rotated so that the quadrate slot engages with an edge of the PCB. The hook of the locking member is received in the positioning hole of the slide member by the elastic subassembly. The PCB is thus mounted in the computer. In disassembly, the slide member is pushed to move on the chassis. The hook is drawn out of the positioning slot. The locking member is rotated and moves away from the PCB by the elastic subassembly. The PCB is thus taken out of the computer. The mounting apparatus described above is convenient to mount the PCB. However, the mounting apparatus has a complex structure that increases manufacturing cost.
What is needed, therefore, is a mounting apparatus convenient to fasten a printed circuit board (PCB) and has a simple structure.

Mounting apparatus for printed circuit board


A step attenuator circuit is mounted on a printed circuit board and has a highpass filter network passing high frequency signals and a lowpass filter network passing low frequency signals. The lowpass network presents a high shunt reactance to the high frequency signals. The lowpass network includes an attenuator network. The attenuator network attenuates the low frequency signals by a specified amount. Parasitic capacitance exists between the highpass network and the attenuator network, causing an amount of electrical energy from the high frequency signals to be absorbed by the attenuator network. A first capacitive circuit is used to compensate for parasitic capacitance. The first compensation circuit is connected across the attenuator network and is coupled to the parasitic capacitance. Consequently, the amount of electrical energy from the high frequency signals absorbed by the attenuator network is reduced, and, as a result, the insertion loss of the step attenuator is reduced.

The present invention relates generally to electronic filters for processing communication signals, and more particularly to an electronic filter called a step attenuator and a circuit modification for improving the insertion loss of the step attenuator.
A step attenuator is a filter used primarily (but not exclusively) in a bi-directional cable television (or CATV) network. The step attenuator is also bi-directional. It processes signals transmitted from a headend to a subscriber's home (i.e., "forward path") and also processes signals transmitted from the subscriber's home to the headend (i.e., "return path"). Usually, the forward path signals are transmitted in a higher frequency band than the return path signals. In the United States, for example, the forward path frequency band is 54-1000 MHz and the return path band is 5-42 MHz. A step attenuator is usually installed in the CATV network at a subscriber tap port, just upstream of the subscriber drop cable. Step attenuators are used to equalize signal levels in the return path (and, at the same, time reduce ingress) by introducing graduated amounts (i.e., steps) of attenuation at different points in the CATV network. Step attenuators attenuate signals in the return path by a specified amount, while not disturbing the forward path. A step attenuator (and its operation) are further described in U.S. Pat. No. 5,745,838.
In FIG. 1 herein, a schematic of a prior art step attenuator circuit is shown. A step attenuator 10 includes a housing 12, an input connector 14, an output connector 16, an input conductor 18, and an output conductor 20. Step attenuator 10 includes a highpass filter network 22 connected in parallel with a lowpass filter network 24. Lowpass network 24 includes a resistive attenuator network 26. Highpass network 22 is configured to pass high frequency signals (i.e., in the forward path frequency band) and suppress low frequency signals (i.e., signals in the return path frequency band). Lowpass network 24 is configured to pass the low frequency signals and suppress the high frequency signals. Attenuator network 26 is configured to attenuate the low frequency signals by a specified amount as the signals pass through lowpass network 24. The low frequency signals are attenuated by network 26 independently of the high frequency signals.
Prior art step attenuator 10 has functioned very well in its intended environment for over ten years. In recent years, the high frequency (or forward path) spectrum of CATV networks has been extended. It now extends to 1000 MHz, and is anticipated to go even higher, possibly up to 3000 MHz. As signal frequencies approach 1000 MHz and higher, the parasitic capacitance in a step attenuator circuit begins to adversely affect performance. In particular, the parasitic capacitance between highpass network 22 and attenuator network 26 causes leakage of high frequency signal currents (or "leakage currents") from network 22 to network 26 where the power or energy of the leakage currents is absorbed (i.e., lost) in the resistive or lossy elements of network 26 (i.e., I2R loss). These leakage currents establish high frequency voltages across R3 and R1 (FIG. 1). This lost power manifests itself in the form of a higher insertion loss for the step attenuator, and is particularly noticeable at ultra high frequencies (UHF) above 750 MHz.
Lowpass network 24 is implemented as an elliptic-function lowpass filter, as indicated by the characteristic inductor/capacitor shunt branches, C6/L4 and C7/L5 in FIG. 1. In an elliptic-function filter, inductors in the shunt branches (L4 & L5) present a high shunt reactance to any of the high frequency signals that reach them. The leakage currents of the high frequency signals (from highpass network 22) will be substantially reflected by the L/C shunt branches (and also by series inductors L3 & L6) in lowpass network 124, and will thus flow through resistors R1-R3 of attenuator network 26 (FIG. 1). This concentration of leakage currents in network 26 provides a worse case for the I2R power loss of the high frequency signals. Thus, an elliptic-function implementation of lowpass network 24 is less than ideal in a step attenuator circuit, if the only goal is to minimize the adverse effects of parasitic capacitance. However, an elliptic-function lowpass network is usually chosen for a step attenuator, because it provides a sharper transition region than most implementations for a given number of electrical components used (i.e., it is an efficient design) and it provides a relatively flat passband response while still achieving a good transition region (usually a tradeoff). Thus, rather than switch to an implementation that has only a capacitor or capacitors in the shunt branch (providing a lower reactance to the high frequency signals), e.g., as shown in FIG. 1 of U.S. Pat. No. 6,784,760, it would be more desirable to find another solution to minimize the effects of parasitic capacitance.
FIG. 2 is a simulated plot of the frequency response for step attenuator 10. As shown, a low frequency response 32 (i.e., 5-42 MHz) is attenuated about 6 dB by attenuator network 26. A high frequency response 34 (i.e., 54-1000 MHz) exhibits little attenuation over a broad range of frequencies, but a noticeable amount of insertion loss 36 (or attenuation) appears above 750 MHz. As explained above, insertion loss 36 is caused (at least in significant part) by the parasitic capacitance between highpass network 22 and attenuator network 26. Heretofore, insertion loss 36 has been tolerable. However, as television service extends to 1000 MHz and above, insertion loss 36 becomes less and less tolerable, especially when additional equipment is being used in the subscriber's home (which is becoming more and more the case). A solution to correct or improve (i.e., reduce) the insertion loss is needed.
Known techniques to minimize parasitic capacitance in high frequency circuits have included (1) careful layout of circuit components and traces on the printed circuit board (PCB), (2) ample separation of the components and traces, and (3) the use of shielding, ground planes, and/or terminations where possible. Certainly, the technique of carefully laying out components and traces has been employed with success in step attenuators and like filters. However, as shown in FIG. 2, a noticeable amount of insertion loss (36) still remains at the ultra high frequencies above 750 MHz. Step attenuators are designed to be very small and compact so that they can be conveniently installed at the subscriber tap ports. Thus, there is little room for separating circuit components and board traces in current step attenuator packages.
To achieve compact size, step attenuator circuits are usually mounted on both sides of a small circuit board. If metal shields are used to minimize parasitic capacitance, all of the circuit components may need to be relocated to one side of the circuit board, thus requiring a significantly larger board. Thus, the shielding technique may not be an optimum solution, and would likely add to the cost of manufacturer. Step attenuators need to be low cost devices, because a great number of them are usually deployed throughout a communication network. The use of ground planes (e.g., sandwiched between layers of printed circuit board) to reduce parasitic capacitance may also add to the cost and complexity of manufacture and produce unintended stray capacitance, resulting in frequency response roll-off. Thus, a more optimum solution to reduce the effects of parasitic capacitance is needed.

Step attenuator circuit with improved insertion loss