An object throwing and catching apparatus having a strap with handles and bridging members to define an object receiving area around netting or solid material. Elastic strips are present in the bridging members to cause them to contract creating a cradle effect in the netting. Such a cradle enhances control of the object to be thrown and caught and enables the object to be easily catapulted via the snap action created by the cradle. For use with water balloons, bursting clips and netting knots may be provided on the apparatus to facilitate breakage of the water balloon. VELCRO fasteners may also be provided on the receiving surface of the apparatus as well as the ball to be caught to facilitate overall control.

The present invention relates generally to an apparatus for throwing and catching objects. More specifically, the present invention relates to a game or sports apparatus for throwing and catching balls, water balloons or the like that can be propelled.
In prior art game and sporting apparatus, particularly throwing and catching devices, it has been well known to employ two handles with a length or area of material therebetween to catch and hold the object being propelled. Typically, at least two such devices are used so a number of people may pass the object between one other to enhance enjoyment and interest in the game. Such a prior art device is disclosed in U.S. Pat. No. 3,342,491 issued to Padovani. This patent discloses a projecting and catching device which employs two handles with a resilient net disposed therebetween to provide the surface for contact the ball during play. The net has an overall shape that is fixed and predetermined at the time of manufacture. The netting simply bridges the two handles to provide a surface that may be stretched according to the desire of the user. U.S. Pat. No. 3,342,491 provides a flat netting surface.
A device sold by Kenner Toys under the trademark SKYBALL also employs a flexible netting with handles for throwing and catching objects, preferably balls. The SKYBALL device provides no means to retain and control the ball on the netting during catching or throwing.
Another prior art game apparatus, U.S. Pat. No. 4,234,183 issued to Stephens, has similar features as U.S. Pat. No. 3,342,491 but also includes a ball locating opening to maintain the ball on the netting portion of the device. As in the Padovani patent, U.S. Pat. No. 4,234,183 discloses a flat netting surface for contact with the object to be thrown or caught.
A flat surfaced throwing and catching game, as in U.S. Pat. No. 4,303,247 issued to Faln, discloses a device where the ball has hook and loop fasteners, such as VELCRO, while the surface of the device has a series of fasteners complimentary to those on the ball. The material of the device is flexible and requires the presence of the VELCRO thereon to secure and maintain the ball on its surface.
Non-flat ball projector and catching devices are known, as disclosed in U.S. Pat. No. 3,467,381 issued to Kreiss. This device a has a cup to hold the ball or object with two retractable members which trap the ball inside the cup. To release the ball, opposing handles connected to the retractable members are pulled away from each other opening a gap large enough for the ball to fit through. This device requires many mechanical parts which adds significantly to the complexity and cost of manufacture.
Therefore, it is desirable in the field of throwing and catching devices for objects, particularly balls, to have a device that is easy and fun to use with comfort while providing a sportlike game. It is further desirable to have a popular product that can be manufactured inexpensively. A throwing and catching device that employs a unique means for controlling the ball during throwing or catching is also desired.

Apparatus for throwing and catching objects


An annular collet (10) is externally fitted to a support rod (4) inserted into a housing (2), and an annular transmission member (14) is arranged around the collet (10) with an annular tapered clearance (C) interposed therebetween. A large number of balls (B) inserted into the annular tapered clearance (C) are pushed up by a pushing spring (17). When pressurized oil is supplied to a hydraulic actuation chamber (25), a clamping piston 24 moves the transmission member (14) downward, so that a tapered internal peripheral surface (15) of the transmission member (14) gets engaged with a tapered external peripheral surface (11) of the collet (10) while rolling the balls (B). Thereby, the collet (10) is diametrically contracted.

1. Field of the Invention
The present invention relates to a clamping device of the type adapted to hold and fix a rod by a collet and is a technique favorable for clamping, for example a support rod of a work support for a machine tool at a predetermined height.
2. Description of the Earlier Technology
There is such a clamping device of this collet-type as constructed to diametrically contract the collet by engaging a tapered internal surface of a cylindrical transmission member with a tapered external surface of the collet and to hold and fix a support rod by that diametrically contracted collet (for example, Japanese Utility Model Publication No. 6-7868 proposed previously by the Assignee of the present Application).
By the way, when increasing the foregoing holding and fixing force, it is necessary to decrease a taper angle for engagement.
In the above-mentioned technique, however, when the taper angel for engagement is decreased, since a static friction force acting between the engaged surfaces is increased at the beginning of disengagement, the disengagement becomes impossible due to that large static friction force.
Therefore, in the prior art, the taper angle for engagement could be set merely to a small value from about 6 degrees to about 10 degrees, so that the increasing of the holding and fixing force was limited.


A compatible optical pickup compatibly using a high density recording medium and at least one low density recording medium, includes an objective lens to form a light spot suitable for use on a recording surface of the high density recording medium by focusing a corresponding incident light beam with a high NA suitable for the high density recording medium and a light spot suitable for use on another recording surface of the low density recording medium by focusing another corresponding incident light beam, and an actuator provided to apply tilt to the objective lens. The light beam for the low density recording medium is incident on the objective lens as a divergent beam. When the objective lens is shifted in a radial direction, a tilt is applied to the objective lens corresponding to the shift.

1. Field of the Invention
The present invention relates to a compatible optical pickup, and more particularly, to a compatible optical pickup which can correct a spherical aberration generated due to the difference in thickness between recording media by using a divergent light beam with respect to a recording medium having a thickness deviated from optimal design conditions of an objective lens.
2. Description of the Related Art
In general, an optical recording and/or reproducing apparatus records information on or reproduces information from an optical disc by using a light spot focused by an objective lens. In the optical recording and/or reproducing apparatus, a recording capacity of the optical disc is determined by a size S of a light spot formed by the optical recording and/or reproducing apparatus. The size S of a light spot is proportional to the wavelength λ of a light beam and is inversely proportional to the numeric aperture (NA) of the objective lens, as shown in Mathematical Formula 1 below.S∝λ/NA  Mathematical Formula 1Thus, to reduce the size S of the light spot formed on the optical disc so as to increase the density of the optical disc, it is necessary to use a short wavelength light source, such as a blue-violet laser, and to use an objective lens having an NA of 0.6 or more.
Also, when the inclination angle, refractive index, and thickness of an optical disc is θ, n, and d, respectively, and the numerical aperture of the objective lens is NA, a coma aberration W31 generated by the inclination of the optical disc can be expressed in Mathematic Formula 2 below.
                              W          31                =                              -                          d              2                                                                                n                  2                                                                  (                                                            n                      2                                        -                    1                                    )                                                          sin                                                                                θ                                                                                cos                                                                                θ                                                      (                                                      n                    2                                    -                                                            sin                      2                                                            θ                                                  )                                            5                /                2                                                        N                                                                          A            3                                              Mathematical                                                  Formula                                                  2            Here, the refractive index n and thickness d of the optical disc indicate the refractive index and thickness of an optical medium from a light incident surface to a recording surface, respectively.
In consideration of Mathematical Formula 2, the thickness of the optical disc needs to be reduced in order to secure allowance with respect to the inclination of the optical disc while allowing the NA of the objective lens to be increased to provide higher density discs.
The thickness of the optical disc has been reduced from 1.2 mm in a compact disc (CD) to 0.6 mm in a digital versatile disc (DVD). In the future, the thickness will probably be reduced to 0.1 mm in a next generation DVD, a so-called HD-DVD (high density digital versatile disc) whose density is higher than the DVD. Of course, the NA of the objective lens has increased from 0.45 in the CD to 0.6 in the DVD. In the next generation DVD (i.e., the HD-DVD), the NA of the objective lens will probably be more than 0.6 and could be, for example, 0.85. Also, considering the recording capacity, it is highly likely the next generation DVD will use a blue-violet light source. Here, the compatibility with the existing optical discs is considered in the development of optical discs having new specifications.
For example, since the reflectivity of a DVD-R or a CD-R, which can record once, is sharply reduced according to a wavelength, it is necessary to use light sources having a wavelength of 650 nm and 780 nm. Thus, considering compatibility with the DVD-R and/or CD-R, an optical pickup for the next generation DVD needs to use two or three light sources having different wavelengths. When a compatible optical pickup uses a plurality of light sources having different wavelengths, it is preferable to use a single objective lens considering a variety of merits such as the size, easiness in assembly, and cost of an apparatus. When optical discs having different thicknesses are compatibly recorded and/or reproduced with a single objective lens, a spherical aberration is generated due to the difference in thickness between the optical discs. Thus, the compatible optical pickup should correct the spherical aberration so that optical discs having different thicknesses can be recorded and/or reproduced by using a single objective lens only.
In Korean Patent Application No.1997-42819 and corresponding Korean Patent Publication No. 1999-19439, the present applicant has suggested a CD and DVD compatible optical pickup having an optical arrangement in which an objective lens is optimally designed with respect to a DVD. Thus, a first light beam having a wavelength of 650 nm for the DVD is incident on the objective lens as a parallel beam. A second light beam having a wavelength of 780 nm for a CD and having a thickness of a substrate out of a range of design conditions of the objective lens is incident on the objective lens as a divergent beam. As such, the spherical aberration due to the difference in thickness of a substrate between a DVD and a CD can be corrected when the CD is used. However, when the divergent beam is used as in the above device, during reproduction of an eccentric optical disc, the coma aberration is greatly generated when the objective lens is shifted in a radial direction of the optical disc. Thus, a tracking error signal and a reproduction signal are further deteriorated when reproducing the eccentric optical disc.
In the configuration of a compatible optical pickup capable of compatibly using a next generation DVD and an optical disc having a density lower than the next generation DVD (such as a CD and/or a DVD), while no such device has been created or suggested, assuming that the objective lens is designed to be suitable for the next generation DVD having the highest density and a divergent beam is used for the CD and/or DVD such that the spherical aberration can be corrected and working distance can be secured, an additional problem would remain. Specifically, when a divergent beam is used in an optical pickup for a next generation DVD family optical disc (hereinafter, referred to as the next generation DVD) as a method to compatibly use the existing DVD family optical disc (hereinafter, referred to as the DVD) and the CD family optical disc (hereinafter, referred to as the CD), although the spherical aberration due to the wavelength and the difference in thickness of the optical discs could be corrected, an optical path difference (OPD) would be created due to the shift of the objective lens in a radial direction of the optical disc when an eccentric optical disc is being reproduced. In particular, the coma aberration would be generated greatly. The created OPD deteriorates a tracking error signal and a reproduction signal.
That is, a high level of technology is required to design and manufacture an objective lens capable of using a next generation DVD, a DVD, and/or a CD as a single lens. Also, it is difficult to make long working distances to be the same as that of an objective lens for a DVD that is designed optimal to the DVD.
According to technology in the field to which the present invention pertains, the objective lens is typically designed to have a working distance of about 0.6 mm with respect to a blue-violet light source and a thickness of 0.1 mm. When light spots are formed on the recording surfaces of a DVD and a CD by focusing a light beam having a 650 nm wavelength for the DVD and a light beam having a 780 nm wavelength for the CD using the objective lens having a high NA designed to the thickness of 0.1 mm and the blue-violet light beam, the working distances are 0.32 mm and −0.03 mm, respectively. That is, the CD and the objective lens collide.
However, if the light source for a CD is arranged at a position deviated from a position of the focal point of a collimating lens (i.e., a position shorter than the focal length) so that the light beam having the 780 nm wavelength is incident on the objective lens in the form of a divergent beam, the working distance can be secured and the spherical aberration due to the difference in thickness between the next generation DVD and the CD and the difference in wavelength therebetween can be corrected. Also, when a light beam for the DVD is divergent when incident on the objective lens, the spherical aberration due to the difference in thickness between the next generation DVD and the DVD and the difference in wavelength therebetween can be corrected.
However, when the divergent beam is used for the CD and/or DVD, although it is possible to correct the spherical aberration and secure a sufficient working distance, the optical pickup becomes a finite optical system. Thus, when a shift of the objective lens in a radial direction of the optical disc is generated, such as when an eccentric optical disc is being recorded or reproduced, the coma aberration is greatly generated so that the aberration characteristic is abruptly deteriorated. In particular, the deterioration of the tracking signal and the reproduction signal becomes severe due to the coma aberration.

Compatible optical pickup applying tilt to objective lens in proportion to radial movement of objective lens


An apparatus for storage and dispensing of a gas, comprising a gas storage and dispensing vessel holding a physical sorbent medium and gas adsorbed on the physical sorbent medium, wherein a carrier gas, e.g., helium, hydrogen, argon, etc., is flowed through the vessel to effect desorption of the sorbate gas and entrainment of the desorbed gas in the carrier gas stream. The storage and dispensing system of the invention may be employed to provide the dispensed sorbate gas to a downstream locus of use in applications such as epitaxial film formation and ion implantation, in the manufacture of semiconductor devices.

1 . Field of the Invention
This invention relates generally to storage and dispensing systems for the selective dispensing of fluids from a vessel in which the fluid component(s) are sorptively retained by a sorbent medium, and are desorptively released from the sorbent medium in the dispensing operation. More specifically, the invention relates to such type of storage and dispensing system from which the sorbate fluid is supplied by flow of carrier gas through the storage and dispensing system during the dispensing operation.
2. Description of the Related Art
In a wide variety of industrial processes and applications, there is a need for a reliable source of process fluid(s), which is compact, portable, and available to supply the fluid(s) on demand. Such processes and applications include semiconductor manufacturing, ion implantation, manufacture of flat panel displays, medical treatment, water treatment, emergency breathing systems, welding operations, space-based applications involving dispensing of liquids and gases, etc.
U.S. Pat. No. 4,744,221 issued May 17, 1988 to Karl O. Knollmueller discloses a method of storing and subsequently delivering arsine, by contacting arsine at a temperature in the range of from about -30.degree. C. to about .+-.30.degree. C. with a zeolite of pore size in the range of from about 5 to about 15 Angstroms to adsorb arsine on the zeolite, and then dispensing the arsine by heating the zeolite to an elevated temperature of up to about 175.degree. C. for sufficient time to release the arsine from the zeolite material. Knollmueller utilizes thermal desorption to effect dispensing of the arsine at elevated pressures. An optical sensor or spectrophotometer is described in the patent as being used to monitor arsine concentrations. The Knollmueller system operates at pressures that are >15 psig and at temperatures in excess of 60.degree. C. to dispense arsine at concentrations of 15-60% by volume.
U.S. Pat. No. 5,518,528 issued May 21, 1996 in the names of Glenn M. Tom and James V. McManus, describes a gas storage and dispensing system, for the storage and dispensing of gases, e.g., hydride gases, halide gases, organometallic Group V compounds, etc., which overcomes various disadvantages of the gas supply process disclosed in the Knollmueller patent.
The gas storage and dispensing system of the TQm et al. patent comprises an adsorption-desorption apparatus, for storage and dispensing of gases, including a storage and dispensing vessel holding a solid-phase physical sorbent medium, and arranged for selectively flowing gas into and out of the vessel. A sorbate gas is physically adsorbed on the sorbent medium. A dispensing assembly is coupled in gas flow communication with the storage and dispensing vessel, and provides, exteriorly of the vessel, a pressure below the vessel's interior pressure, to effect desorption of sorbate gas from the solid-phase physical sorbent medium, and flow of desorbed gas through the dispensing assembly. Heating means may be employed to augment the desorption process, but it is preferred to operate the Tom et al. system with the desorption being carried out at least partially by pressure differential-mediated release of the gas from the sorbent medium.
The storage and dispensing system of the Tom et al. patent embodies a substantial advance in the art, relative to the prior art use of high pressure gas cylinders. Conventional high pressure gas cylinders are susceptible to leakage from damaged or malfunctioning regulator assemblies, as well as to rupture and unwanted bulk release of gas from the cylinder if the internal gas pressure in the cylinder exceeds permissible limits. Such over-pressure may for example derive from internal decomposition of the gas leading to rapid increasing interior gas pressure in the cylinder.
The fluid storage and dispensing system of the Tom et al. patent thus reduces the pressure of stored sorbate gases by reversibly adsorbing them onto a sorbent medium, e.g., a zeolite or activated carbon material.
A fluid storage and dispensing system of the general type disclosed in the Tom et al. patent, hereafter referred to as an "FSDS," is commonly used in association with low pressure end use applications, such as ion imnplantation in semiconductor manufacturing processes, that provide a pressure differential, .DELTA.P, between the near-ambient interior pressure of the storage and dispensing vessel, P.sub.FSDS, and the low pressure of the downstream process in which the dispensed fluid is used, P.sub.use. The near-ambient pressure of the FSDS vessel's interior volume may for example be on the order of 600 to 800 torr, and the pressure of the downstream process may for example be below 500 torr.
In these low pressure applications, the pressure differential, .DELTA.P=P.sub.FSDS -P.sub.use, is favorable for extracting the sorbate fluid from the FSDS vessel, including the fluid in the head space and in the interstices of the bed of sorbent material (typically present as a bed of particulate, pelletized, bead, granular or other finely divided material having affinity for the sorbate gas species of interest), as well as effecting desorption of the sorbate fluid from the sorbent material by virtue of the pressure differential.
Difficulties arise, however, in dispensing fluid from an FSDS when the pressure level of the downstream process is at atmospheric or slightly below atmospheric pressure, and the pressure differential, .DELTA.P=P.sub.FSDS -P.sub.use, is very low. In many instances, this pressure differential driving force (for mass transfer of the sorbate gas from the sorbent material into the surrounding gas phase of lower concentration of the sorbate species) is by itself inadequate to achieve the desired rate of dispensing of the sorbate gas.
Under such atmospheric or near-atmospheric dispensing conditions, therefore, there exists little or no driving force for mass transfer, i.e., there is little or no pressure gradient for achieving release of the sorbate fluid from the sorbent medium. As a result, only low or even minimal mass transfer of the sorbate gas may be possible. This is true for sub-atmospheric pressure processes, such as chemical vapor deposition (CVD) of tetraethylorthosilocate (TEOS), and is especially true in applications such as silicon epitaxy and other processes operating at atmospheric pressure.
An alternative means of achieving the desired desorption is the use of heat inputted to the sorbent material to mediate thermal desorption. Heating of the sorbent material in the storage and dispensing vessel of the FSDS shifts the equilibrium isotherm of the sorbent material so that the sorptive capacity of the sorbent material for the sorbate fluid is reduced. This in turn facilitates the desorption of the sorbate fluid from the sorbent material as the sorbent material is heated.
At the same time, however, the sorbent material has a finite heat capacity, and this "thermal mass" prevents the sorbent material from being instantly cooled when the input of heat is terminated at the fmish of the dispensing operation. As a result, even though the dispensing of the sorbate fluid has been concluded, fluid continues to desorb from the hot sorbent material and remain in the desorbed state, causing an overpressure in the FSDS vessel. Such pressure increase is at odds with the desired low pressure condition for the FSDS vessel interior volume, and the pressure increase may with significant heating create a hazardous high pressure level in the FSDS vessel.
It is an object of the present invention to provide an improved fluid storage and dispensing apparatus and method which overcome the aforementioned difficulties of the prior art.
It is another object of the present invention to provide an improved fluid storage and delivery system which utilizes little or no heating to supply the sorbate fluid for downstream applications which are at atmospheric pressure or above-atmospheric pressure levels.
It is a further object of the present invention to provide an improved means of controlling the dispensing flow rate and concentration of sorbatel fluid from a fluid storage and dispensing system.
Other objects and advantages of the invention will be more fully apparent from the ensuing disclosure and appended claims.

Throughflow gas storage and dispensing system


A method and apparatus for improving servo stability in read heads while writing is disclosed. In one embodiment, a magnetic storage device includes a disk surface and a transducer. The disk surface has servo information and user data stored thereon. The transducer includes a read head and a write head. The read head is operable to read servo information and user data from the disk surface. The write head is operable to write user data onto the disk surface. The read head is biased by a first bias current when reading user data and servo information from the disk surface during a read operation. The read head is biased by a second bias current when reading servo information from the disk surface during a write operation. The second bias current, which is different from the first bias current, is selected to increase servo stability in the read head when writing. Further, the write current may also be modified from a standard value in order to increase servo stability in the read head while writing.

Computer disk drives store information on magnetic disks. Typically, the information is stored on each disk in concentric tracks that are divided into sectors. Information is written to and read from a disk by a transducer that is mounted on an actuator arm capable of moving the transducer radially over the disk. Accordingly, the movement of the actuator arm allows the transducer to access different tracks. The disk is rotated by a spindle motor at high speed which allows the transducer to access different sectors on the disk.
A conventional disk drive, generally designated 10, is illustrated in FIG. 1. The disk drive comprises a disk 12 that is rotated by a spin motor 14. The spin motor 14 is mounted to a base plate 16. An actuator arm assembly 18 is also mounted to the base plate 16.
The actuator arm assembly 18 includes a transducer 20 mounted to a flexure arm 22 which is attached to an actuator arm 24 that can rotate about a bearing assembly 26. The actuator arm assembly 18 also contains a voice coil motor 28 which moves the transducer 20 relative to the disk 12. The spin motor 14, voice coil motor 28 and transducer 20 are coupled to a number of electronic circuits 30 mounted to a printed circuit board 32. The electronic circuits 30 typically include a read channel chip, a microprocessor-based controller and a random access memory (RAM) device.
The disk drive 10 typically includes a plurality of disks 12 and, therefore, a plurality of corresponding actuator arm assemblies 18. However, it is also possible for the disk drive 10 to include a single disk 12 as shown in FIG. 1.
FIG. 2 is an air-bearing surface view of a transducer 20. As shown in FIG. 2, the transducer 20 includes functionally separate write and read heads 40, 42, respectively. More specifically, the transducer 20 typically includes a write element 200, a write gap 204, a first shield 208, a second shield 212, a read gap 216 and a magneto-resistive read element (or giant magneto-resistive read element) 220.
FIG. 3 is a simplified top view of a disk 12 illustrating a conventional embedded servo system (also known as sectored servo system). As illustrated in FIG. 3, the disk 12 includes a plurality of concentric tracks 44 for storing data on the surface of the disk. Although FIG. 3 only shows a relatively small number of tracks (i.e., 8), for ease of illustration, it should be appreciated that typically many thousands of tracks are included on the surface of a single disk 12.
Each track 44 is divided into a plurality of data sectors 46 and a plurality of servo sectors 48. The servo sectors 48 in each track are radially aligned with servo sectors 48 in the other tracks, thereby forming servo wedges 50 which extend radially across the disk 12. The servo sectors 48 are used to position the read head 42 and write head 40 associated with each disk 12 during operation of the disk drive 10.
In general, the transducer 20 has three modes of operation. First, the transducer 20 may read servo data located within servo sectors 48 using the read head 42. Second, the transducer 20 may read customer data located within data sectors 46 using the read head 42. Third, the transducer 20 may write customer data into data sectors 46 using the write head 40.
As is well understood by those skilled in the art, the first mode of operation of the transducer 20 (i.e., reading servo data) is used in conjunction with the second and third modes of operation (i.e., reading customer data and writing customer data, respectively). Specifically, the servo data must be read in connection with performing the operations of reading and writing customer data so that the read head 42 and the write head 40 are properly positioned over the disk surface (i.e., over the correct track 44 and data sector 46) when such operations are performed.
More specifically, when performing a read operation, servo data located in servo sectors 48 is read by read head 42 to properly position the read head 42 both radially and circumferentially over the disk 12. Customer data is then read from one or more data sectors 46 using the read head 42. While customer data is being read from the disk 12, the read head 42 is unable to make adjustments in its position over the disk 12. Accordingly, servo data located in servo sectors 48 is periodically read to make positional adjustments of the read head 42.
Similarly, when performing a write operation, servo data located in servo sectors 48 is read by read head 42 to properly position the write head 40 both radially and circumferentially over the disk 12. Customer data is then written to one or more data sectors 46 using the write head 40. While customer data is being written onto the disk 12, the read head is unable to make adjustments in the position of the write head 40 over the disk 12. Accordingly, servo data located in servo sectors 48 is periodically read by the read head 42 to make positional adjustments of the write head 40. It should be noted, however, that the write current to the write head 42 is turned off prior to the read head 42 reading servo data.
As is understood by those skilled in the art, the read head 42 and write head 40 are spaced apart from one another by a small distance in a downtrack direction (see FIG. 2). (In some cases, the read head 42 and write head 40 may also be spaced apart from one another by a small distance in a cross-track direction.) Because of this spacing, the read head 42 and write head 40 are generally unable to follow the same path over the disk 12. The amount by which the paths of the read and write heads 42, 40 differ (i.e., the skew) depends upon the radial position of the transducer 20 over the disk 12. Accordingly, the track over which the read head 42 is positioned will generally be different from the track over which the write head 40 is positioned. Thus, when performing a write operation, the position of the transducer 20 is adjusted after reading servo data from a servo sector 48 to properly position the write head 40 over the appropriate data track 44. This adjustment is known as "microjogging."
Information is capable of being written onto or read from the surface of the disk 12 because the disk 12 is coated with a magnetic material that is capable of changing its magnetic orientation in response to an applied magnetic field. Writing is performed by delivering a write signal having a variable current to the write head 40 while the write head 40 is held close to the track 44 and data sector 46 to which such data is to be written. The write signal creates a variable magnetic field at a gap portion of the write head 40 that induces magnetic polarity transitions onto the surface of the disk 12 which constitute the data being stored.
Reading is performed by sensing the magnetic polarity transitions on the rotating track with the read head 42. As the disk 12 spins below the read head 42, the magnetic polarity transitions on the track present a varying magnetic field to the read head 42. The read head 42 converts the varying magnetic field into an analog read signal that is then delivered to a read channel (not shown) for appropriate processing. The read channel converts the analog read signal into a properly-timed digital signal that can be recognized by a host computer system (not shown).
More specifically, a read head 42 typically has an MR read element (or a GMR read element), which includes a strip of magneto-resistive material that is generally held between two magnetic shields. The resistance of the magneto-resistive material varies almost linearly with applied magnetic field. During a read operation, the MR strip is held near a desired track, with the varying magnetic field caused by the magnetic transitions on the track. A constant DC current (known as a bias current) is passed through the strip resulting in a variable voltage across the strip. By Ohm's law (i.e., V=IR), the variable voltage is proportional to the varying resistance of the MR strip and, hence, is representative of the data stored within the desired track. The variable voltage signal (which is the analog read signal) is then processed and converted to digital form for use by the host computer.
One problem with many conventional disk drives is that they suffer from a phenomenon known as write-induced instabilities. That is, when performing a write operation, the magnetic flux generated by the write head 40 to record information onto the disk surface has an affect on the read head 42 (after the write current is turned off) which prevents the read head 42 from properly reading servo data from the servo sectors 48. Specifically, during a write operation, after the write current to the write head 40 has been turned off and the read head 42 is being used to read servo data to properly position the write head 40, the read head 42 may not be able to properly read servo data from servo sectors 48.
More specifically, an instability is created in the domains of the read head 42 (e.g., in one or both of the shields, permanent magnet or MR/GMR element) due to the flux generated by the write current that is applied to the write head 40 while writing customer data onto the disk 12. This instability causes a large perturbation for a short period of time (e.g., 1-2 microseconds). Accordingly, the read signal generated when reading servo data from a servo sector 48, immediately after writing customer data to a data sector 46, is corrupted. Thus, the write head 40 may be positioned in an erroneous location over the surface of the disk 12 or the read head 42 must be permitted to re-read the servo data (by the disk spinning an entire revolution) before resuming the write operation. As will be appreciated, the performance of the drive, which is required to write information with high speed and high accuracy, can be significantly diminished by write-induced instability errors.
In order to ensure that disk drives 10 having transducers 20 that suffered from write-induced instabilities were not shipped to consumers, several tests were developed. Many of these tests require a drive to be manufactured before testing occurs. Accordingly, when a drive fails one of these tests, it is required to be discarded or reassembled (with new read head(s)), resulting in reduced manufacturing yield and manufacturing throughput, as well as, increased manufacturing costs.
For example, one of these tests is known as a WIPE test (write-induced position error test). In the WIPE test, many write operations are performed on each disk surface and every time servo data is determined to be corrupted, such errors are recorded on a head-by-head basis. The instability error rate for each head of a drive is then compared to a target instability error rate to determine whether a drive is within acceptable parameters to be sold to consumer. Again, if a drive fails the test, it is either discarded or disassembled, resulting in a loss of time and money for a disk drive manufacturer.
It would be advantageous to provide a method and apparatus for improving servo stability in MR heads while writing. More specifically, it would be advantageous to provide a method and apparatus for reducing instances of write-induced instabilities, so that manufacturing yields may be increased, manufacturing throughput can be increased and manufacturing costs can be decreased.

Method and apparatus for improving servo stability in read heads while writing


The fluid distribution discs include a plurality of fluid distribution channels that radiate from the fluid distribution disc origin to conically shaped tines connected at the perimeter of the fluid distribution disc. The fluid distribution channels are aligned with similar channels within a bushing securable to the fluid distribution disc radial portion. A stationary plate or disc valve has a disc valve fluid channel in a disc valve radial surface, which is in contact with the rotating bushing radial surface resulting in a periodic alignment between the disc valve fluid channel and each of the bushing channels. Fluid is pumped to a fluid port in a hub having a fluid port in fluid communication with the disc valve fluid channel. As the tines of the fluid distribution disc penetrate the field surface, fluid is channeled through the disc valve into the fluid distribution disc channels and the tines. Fluid leakage from disc valve radial surface/rotating bushing radial surface interface is captured and redirected by a bleed groove though the tines at point after a tine has entered the ground and before the fluid is delivered to the tine through the disc valve fluid channel.

1. Field of the Invention
This invention is relevant to the field of soil treatment apparatuses.
2. Discussion of the Related Art
Fertilizer is a common and preferred treatment used in modern agriculture. Liquid fertilizers are often preferred for their ease of delivery to agricultural roots systems. Prior apparatus are disclosed in the following United States or foreign patents; U.S. patent application No. 200256554 J W Hargraves et al., U.S. Pat. No. 5,769,169 F J Mikstiz, U.S. Pat. No. 5,353,724 R B Wheeley, Jr., U.S. Pat. No. 5,178,078 D B Pendergrass, U.S. Pat. No. 4,919,060 W F Cady, U.S. Pat. No. 4,677,921 M A Brown, U.S. Pat. No. 4,649,836 L Overocker, U.S. Pat. No. 4,677,921 M J Kordon, U.S. Pat. No. 4,034,686 W C Collens, U.S. Pat. No. 3,926,131 W C Collens, U.S. Pat. No. 3,716,005 J W Fennell, U.S. Pat. No. 3,602,166 M L Peterson, U.S. Pat. No. 3,211,114 B Ucinhaska, U.S. Pat. No. 3,143,090 R D Cecil et al., U.S. Pat. No. 3,025,806 A W Peck, U.S. Pat. No. 2,975,735 W T Purvance, U.S. Pat. No. 2,876,718 J B Vaughan, U.S. Pat. No. 2,866,422 R L Colson, U.S. Pat. No. 2,845,884 P K Clausing et al., FR1107575 De Lomine et al., U.S. Pat. No. 2,649,060 C A Hawkins et al., U.S. Pat. No. 2,649,061 C A Hawkins et al., GB643395, U.S. Pat. No. 2,384,469 J Kalix, U.S. Pat. No. 2,139,306 C Gaffney, U.S. Pat. No. 2,072,331 W R Hanna, U.S. Pat. No. 1,871,529 G C Karshner, U.S. Pat. No. 1,424,728 H Knight et al., U.S. Pat. No. RE15151 H Knight, U.S. Pat. No. 1,359,177 H Knight, U.S. Pat. No. 1,171,277 H D Thayer, U.S. Pat. No. 1,117,333 W Cooper, DE225866 A Lucht, U.S. Pat. No. 5,107,895. However, none of the above patents however disclose the aspects of the current invention.

Fluid distribution assembly having bleed groove for leakage


This invention relates to protein structures, to methods of producing those protein structures, and to peptides used in the formation of the protein structures.

As our understanding of sequence-to-structure relationships in proteins improves, so does our ability to rationally design new proteins and protein-based materials. Unlike discrete peptide and protein objects, the design of biomaterials requires additional rules for self-assembly to allow the nano-to-micron scale regimes to be bridged (Woolfson, D. N. & Ryadnov, M. G. Curr. Opin. Chem. Biol. 10, 559-567 (2006); Ulijn, R. V. & Smith, A. M. Chem. Soc. Rev. 37, 664-675 (2008)). In these respects, synthetically accessible peptides, which can be programmed to fold into prescribed structures and to self-assemble into larger architectures, offer routes to rationally designed peptide and protein-based biomaterials. Indeed, a variety of peptide-based self-assembling fibres, tapes and hydrogels have been produced (Zhang, S. G., Holmes, T., Lockshin, C. & Rich, A. Proc. Natl. Acad. Sci. USA 90, 3334-3338 (1993); Aggeli, A. et al., Nature 386, 259-262 (1997); Pandya, M. J. et al., Biochemistry 39, 8728-8734 (2000); Hartgerink, J. D., Beniash, E. & Stupp, S. I. Science 294, 1684-1688 (2001); Schneider, J. P. et al., J. Am. Chem. Soc. 124, 15030-15037 (2002); Paramonov, S., Gauba, V. & Hartgerink, J. Macromolecules 38, 7555-7561 (2005)). Much of this effort has been directed to the assembly of β-structured systems, though α-helix-based fibrous and α-helix-containing gelling materials have been explored to some extent (Pandya et al., 2000 supra; Petka, W. A., Harden, J. L., McGrath, K. P., Wirtz, D. & Tirrell, D. A. Science 281, 389-392 (1998); Wang, C., Stewart, R. J. & Kopecek, J. Nature 397, 417-420 (1999); Potekhin, S. A. et al., Chem. Biol. 8, 1025-32 (2001); Zimenkov, Y., Conticello, V. P., Guo, L. & Thiyagarajan, P. Tetrahedron 60, 7237-7246 (2004); Dong, H., Paramonov, S. E. & Hartgerink, J. D. J. Am. Chem. Soc. 130, 13691-13695 (2008); Gribbon, C. et al., Biochemistry 47, 10365-10371 (2008)).
In WO 2001/021646, the inventors described a self-assembling fibre (SAF) system enabling the sticky-end directed molecular assembly of α-helical coiled coils. The system comprises two short peptides (SAF-p1 and SAF-p2) of de novo design. The SAF-p1 and SAF-p2 sequences were designed to co-assemble, resulting in an offset α-helical dimer with complementary sticky ends. The ends promote longitudinal assembly into α-helical coiled-coil fibrils, which bundle to form matured fibres. Subsequently, the inventors introduced fibre-shaping peptides into the SAF system allowing morphological changes to be made to protein fibres comprising self-assembling peptides (WO 2004/022584).
In viruses (H. F. Lodish, Molecular cell biology. (W.H. Freeman, New York, ed. 6th, 2008)) and certain bacterial microcompartments (S. Tanaka et al., Science 319, 1083 (2008)), capsids and suprastructures are produced via the self-assembly of large folded proteins, usually in highly symmetric manners, and with exquisite positioning of non-covalent protein-protein interactions. Biomimetic assemblies have potential for creating simpler encapsulation systems, and for applications in controlled delivery and release, sensing, and the preparation of protocells for various aspects of synthetic biology (C. M. Agapakis, P. M. Boyle, P. A. Silver, Nat. Chem. Biol. 8, 527 (2012); D. A. Hammer, N. P. Kamat, FEBS Lett. 586, 2882 (2012); M. Uchida et al., Adv. Mater. 19, 1025 (2007)). To these ends, others have produced macroscopic "sacs" from peptide amphiphiles (R. M. Capito, H. S. Azevedo, Y. S. Velichko, A. Mata, S. I. Stupp, Science 319, 1812 (2008)); and engineered micelle-like structures (F. Boato et al., Angew. Chem. Int. Ed. Engl. 46, 9015 (2007); S. Raman, G. Machaidze, A. Lustig, U. Aebi, P. Burkhard, Nanomedicine 2, 95 (2006)), small polyhedra (N. P. King et al., Science 336, 1171 (2012); Y. T. Lai, D. Cascio, T. 0. Yeates, Science 336, 1129 (2012)), extended protein arrays (J. C. Sinclair, K. M. Davies, C. Venien-Bryan, M. E. M. Noble, Nat. Nanotechnol. 6, 558 (2011)), and metal-directed assemblies (J. D. Brodin et al., Nat. Chem. 4, 375 (2012); M. M. Pires, J. Lee, D. Ernenwein, J. Chmielewski, Langmuir 28, 1993 (2012)) using mainly natural peptides and proteins.
The inventors have produced self-assembled cage-like particles, SAGEs, from a set of short, de novo, α-helical, coiled-coil peptides by employing clear sequence-to-structure relationships and rational-design principles to direct stable and highly specific protein-protein interactions. Such sequence-to-structure relationships and rational-design principles are described in E. H. C. Bromley, K. Channon, E. Moutevelis, D. N. Woolfson, ACS Chem. Biol. 3, 38 (2008); A. N. Lupas, M. Gruber, Adv. Prot. Chem. 70, 37 (2005); and D. N. Woolfson, Adv. Prot. Chem. 70, 79 (2005).

Self-assembling peptide cages from coiled-coil peptide modules


An image display apparatus capable of displaying images in similar image groups to allow the user to determine the difference between the images in each of the similar image groups, and to select an image to be deleted or saved in easier and more efficient way. An evaluation value obtaining means calculates an evaluation value representing the desirability of an image for each of the images in each of the similar image groups using a predetermined evaluation criterion. A sorting means rearranges each of the images in each of the similar image groups in the order of the evaluation value to generate a display order. A display control means causes each of the images in each of the similar image groups to be displayed on a display section according to the display order.

1. Field of the Invention
The present invention relates to an image display apparatus and method for displaying a plurality of images. It also relates to a computer-readable recording medium on which a program for causing a computer to execute control for realizing the image display method is recorded. Still further, the present invention relates to a photograph print order accepting apparatus incorporating the image display apparatus of the present invention.
2. Description of the Related Art
Digital cameras may provide an image at a lower cost compared to silver halide film cameras since they require no film cost. As a result, more and more images are obtained by digital cameras. This trend is further encouraged by increasingly larger capacity of recording media detachably provided to digital cameras. As a result, a great number of images are stocked in the recording media of digital cameras, and other recording media including hard disks and CD-R of personal computers and the like on which the image data read out from the recording media of digital cameras are recorded. Those images include both necessary images (good images) and unnecessary images (failed photographs, duplicated images, and the like), which are moreover often left ungroomed.
Organizing such a great number of images is a troublesome task. Consequently, apparatuses for assisting in searching/extracting necessary images, and extracting/deleting unnecessary images from the stocked images, or classifying/organizing stocked images based on the event, date and time, location, and the like are proposed.
One such apparatus is known as described, for example, in Japanese Unexamined Patent Publication No. 2005-141584. The apparatus displays a plurality of candidate images to be deleted at the same time, which are determined to be similar among candidate images to be deleted that satisfy a predetermined deletion criterion, and deletes an unnecessary image based on selection by the user.
As describe in the aforementioned patent publication, however, it is not easy for the user to recognize the difference between the displayed images, and to decide which image should be deleted (saved) even the similar candidate images to be deleted are collectively displayed at the same time.
The present invention has been developed in view of the circumstances described above, and it is an object of the present invention to provide an image display apparatus and method that allows the user to select an image to be deleted or saved from a group of images constituted by a plurality of similar images. It is a further object of the present invention to provide a computer-readable recording medium on which a program for causing a computer to execute control for realizing the image display method of the present invention is recorded. It is a still further object of the present invention to provide a photograph print order accepting apparatus that includes the image display apparatus of the present invention.

Image display apparatus and method, computer-readable recording medium on which the program is recorded, and photograph print order accepting apparatus


A method for provisioning a network element is included where a custom default file and a standard default file are provided in a network element. The custom default file includes one or more default parameters of a same type, but having a different value from, corresponding default parameters in the standard default file. Service parameters are determined based on the default parameters of the standard default file as modified by overriding default parameters of the custom default file. The service is generated based on the service parameters.

Telecommunications systems, cable television systems, and data communications networks may use optical networks to rapidly convey large amounts of information between remote points. In an optical network, information is conveyed in the form of optical signals through optical fibers. Optical fibers comprise thin strands of glass capable of transmitting the signals over long distances with very low loss.
Optical networks may use network elements that provide telecommunications services at discrete points of the network. A network element includes software that provisions the network element and manages the telecommunications services based on standard defaults provisioned to the network element. The standard defaults are generally hardcoded at the network element and are typically set by the supplier of the equipment.

Provisioning a network element using custom defaults


A method for measuring electricity usage that includes steps of: coupling a sensor to a power source; converting a signal from the sensor to a digital measurement signal; using a microcomputer to determine quantities indicative of electricity consumption from the digital measurement signal; and using a nonvolatile, reprogrammable memory coupled to the microcomputer to control the microcomputer in determining the quantities indicative of electricity consumption.

This invention relates generally to electricity metering, and more particularly, to a microcomputer based electricity meter.
Electronic electricity meters for metering multi-phase services typically include a digital signal processor (DSP) and a microcomputer. Certain functions and operations are separately performed in the DSP and microcomputer. By dividing the functionality between the DSP and microcomputer, communications of data and commands must be provided between the DSP and microcomputer. Such an architecture is complex.
In addition, such meters typically are programmed to perform certain functions. Although the meters are upgradeable, the types of upgrades that can be performed are limited to the tables and functions prestored in the meter. In addition, and in the past, increased functionality typically was a trade-off to cost. That is, adding functionality to the meter typically resulted in adding significant costs to the meter.
It would therefore be desirable to provide methods and apparatus for electricity metering that do not require a DSP as well as a microcomputer, and that provide the flexibility of increased functionality by program upgrades.
There is therefore provided, in one embodiment of the present invention, a method for measuring electricity usage that includes steps of: coupling a sensor to a power source; converting a signal from the sensor to a digital measurement signal; using a microcomputer to determine quantities indicative of electricity consumption from the digital measurement signal; and using a nonvolatile, reprogrammable memory coupled to the microcomputer to control the microcomputer in determining the quantities indicative of electricity consumption.
The above-described embodiment performs metering of electricity usage without requiring a DSP. In addition, reprogrammability is provided so that metering upgrades are easily performed.

High function, user configurable electricity meter


A magnetic recording medium having excellent durability and containing carbon black having a mean particle diameter of 25 to 130 nm, a BET specific surface area of 30 to 80 m.sup.2 /g and an oil absorption of 300 to 500 ml/100 g which is incorporated into a magnetic layer of a magnetic recording medium.

1. Field of the Invention
The present invention relates to a magnetic recording medium and more particularly to a magnetic recording medium which is particularly excellent in durability.
2. Description of the Related Art
Carbon black is usually contained in a magnetic layer of a magnetic recording medium. The carbon black is used for the purpose of imparting a light shielding property and an antistatic performance to the magnetic recording medium. There is also a proposal on the combined use of two types of carbon black, which differ from each other in particle diameter, for the purpose of imparting better lubricity to the recording medium.
Studies on the relationship between the selection of carbon black and the durability of the magnetic recording medium containing carbon black have not always been sufficient.

Magnetic recording medium containing carbon black having specific properties


The invention relates to a veneer lathe knife assembly comprising supported by a frame assembly a knife mounting beam (4) and a nose bar beam (5), both of which having a front portion (4xe2x80x2; 5xe2x80x2) for holding a cutting knife (6) and a nose bar (7), respectively, and a stiffening rear portion. The knife mounting beam (4) and the nose bar beam (5) are adapted movable relative to each other on the frame assembly so as to permit adjustment of the knife gap formed between the cutting knife (6) and the nose bar (7). Heat transfer means (2, 2xe2x80x2, 2xe2x80x3, 2xe2x80x2xe2x80x3) are adapted to the stiffening rear portion of both the knife mounting beam (4) and the nose bar beam (5). Both the knife mounting beam (4) and the nose bar beam (5) have placed thereon, in a close vicinity to the knife (6) and the nose bar (7), at least one first set of temperature sensors (3, 3xe2x80x2) disposed in predetermined positions along the length of the knife and the nose bar. Furthermore, both the knife mounting beam (4) and the nose bar beam (5) have placed thereon, at a distance from the knife (6) and the nose bar (7), at least one second set of temperature sensors (1, 1xe2x80x2, 1xe2x80x3, 1xe2x80x2xe2x80x3) disposed in predetermined positions along the length of the knife and the nose bar, whereby the heat transfer means (2, 2xe2x80x2, 2xe2x80x2xe2x80x3, 2xe2x80x3) placed in the stiffening rear portion (4xe2x80x3, 4xe2x80x2xe2x80x3; 5xe2x80x3, 5xe2x80x2xe2x80x3) of both the knife mounting beam (4) and the nose bar beam (5) are adapted controllable for adjusting the respective portions of the knife mounting beam and the nose bar beam under feedback from the second set of temperature sensors to a temperature value derived from the measurement signal given by the first set of temperature sensors.

The invention relates to a knife assembly for a veneer lathe. Conventionally, the knife assembly includes a knife mounting beam and a nose bar beam, both supported by a frame structure. Either one of these elements comprises a beam-like member which extends essentially over the entire length of the lathe and incorporates means required for mounting the opposed blade elements known as the cutting knife and the nose bar. Generally, the opposed sides of the support beam are provided at the fixing points of the blade elements with a plurality of bulkhead-like projecting members that function as stiffeners of the support beam structure. The knife assembly is arranged controllably movable along guides toward the log being peeled in synchronism with the progress of peeling, and, respectively, away therefrom when the peeling of a new log is to be started. The mutual distance between the knife mounting beam and the nose bar beam is made adjustable to control the knife gap between these opposed knife elements. To achieve a good peeling result, it is mandatory to keep the knife gap in a predetermined value over the entire length of the knife mounting beam and the nose bar beam. Hence, accurate control of the knife gap requires both the knife mounting beam and the nose bar beam to be massive structures that are rigid and resistant to bending.
Conventionally, veneer is peeled from soaked wood that has been kept in a water or steam bath in order to elevate the temperature of the log. When entering the lathe station, the temperature of the log may by as high as 80xc2x0 C. Additional heat is generated from the friction of the knife peeling the log and the nose bar running on the log, as well as from the friction of the veneer passing through the knife gap. This heat load is imposed on the knife mounting beam and the nose bar beam within the structures of the beams holding the knife bar and the nose bar. Such a local rise of temperature generates thermal stresses in the knife mounting beam and the nose bar beam that result in minor deformations of these structures. However, the deformations also are reflected in the value of the knife gap that should stay constant to a tolerance of about 0.02 mm over the entire length of the knife and nose bar.
In the prior art a remedy to this problem has been generally sought by way of providing heating means on the rear portions of the knife mounting beam and the nose bar beam that are on the opposite side of the beam relative to the mounting structures of knife and nose bar. Conventionally, such heating has been accomplished by adapting cavities into the reinforcing structures of the rear portions of the beams and then circulating heated medium therein. The goal of these arrangements has been to stabilize the temperature of the entire knife/nose bar assembly at an elevated level. This technique can indeed minimize deformations induced by thermal stresses on the knife mounting beam and the nose bar beam. However, the overall result thus obtained has not been sufficiently well controlled to keep the knife gap at its predetermined value over the entire length of the knife.
A knife assembly, which is implemented according to the invention and comprises in a conventional manner a frame assembly that supports a knife mounting beam and a nose bar beam, both of which having a front portion for holding a cutting knife and a nose bar insert, respectively, and a stiffening rear portion, whereby the knife mounting beam and the nose bar beam are adapted movable relative to each other on the frame assembly so as to permit adjustment of the knife gap formed between them, and further comprises heat transfer means adapted to the stiffening rear portion of both the knife mounting beam and the nose bar beam, offers in accordance with the invention an improvement in controlling the knife gap to a correct predetermined value by virtue of having placed on both the knife mounting beam and the nose bar beam, in a close vicinity to the knife and nose bar at least one first set of temperature sensors disposed in predetermined positions along the length of the knife and nose bar, and, both the knife mounting beam and the nose bar beam having placed thereon at least one second set of temperature sensors, disposed in predetermined positions along the length of the knife and nose bar, at a distance from the knife and the nose bar, and the assembly further having the heat transfer means located in the stiffening rear portion of the knife mounting beam and the nose bar beam, respectively, being adapted controllable for adjusting the respective portions of the knife mounting beam and the nose bar beam under feedback from the second set of temperature sensors to a temperature value derived from the measurement signal given by the first set of temperature sensors.
Next, the invention will be examined in greater detail with the help of the attached drawing, wherein is diagrammatically illustrated a knife assembly of a veneer lathe.


Mesothelin is a differentiation antigen present on the surface of ovarian cancers, mesotheliomas and several other types of human cancers. Because among normal tissues, mesothelin is only present on mesothelial cells, it represents a good target for antibody mediated delivery of cytotoxic agents. The present invention is directed to anti-mesothelin antibodies, including Fv molecules with particularly high affinity for mesothelin, and immunoconjugates employing them. Also described are diagnostic and therapeutic methods using the antibodies. The anti-mesothelin antibodies are well-suited for the diagnosis and treatment of cancers of the ovary, stomach, squamous cells, mesotheliomas and other malignant cells expressing mesothelin.

In many types of cancer cells, differentiation antigens are expressed. These antigens have been used as targets in cancer therapy. For example, CD19, CD20, CD22 and CD25 have successfully been used as targets in hematopoietic malignancies (Press, et al., New Eng. J. Med. 329:1219-1224 (1993); and Osterborg, et al., J. Clin. Oncol. 15:1567-1574 (1997)). However, this targeted cancer therapy has not been successful with solid tumors, in large part because the targeted antigens are also expressed in tissues from which the tumors arose. Thus, such targeted therapies kill healthy cells as well as the malignant cells.
In the United States, despite therapy, an estimated 15,000 women die of ovarian cancer each year. Although less common than ovarian cancer, mesotheliomas are known to be resistant to all chemotherapeutic agents and therefore have a high mortality rate. Because of the morbidity of these cancers, new therapeutic approaches to these malignancies are needed.
Common to ovarian, squamous cell and some stomach cancers as well as mesotheliomas is the expression of mesothelin on the cell surface (Chang, et al., Cancer Res. 52:181-186 (1992); Chang, et al., J. Surgical Pathology 16:259-268 (1992); and Chang, et al., Nat'l Acad. Sci. USA 93:136-140 (1996)). Mesothelin is a 40 kD GPI-linked glycoprotein antigen present on the surface of mesothelial cells. It is synthesized as a 69 kD precursor which is then proteolytically processed. The 30 kD amino terminus is secreted and has been termed megakaryocyte potentiating factor (Yamaguchi, et al., J. Biol. Chem. 269:805-808 (1994)). The 40 kD carboxyl terminus remains bound to the membrane as mature mesothelin (Chang, et al., Nat'l Acad. Sci. USA 93:136-140 (1996)). Unlike many cell surface antigens present on cancer cells, the membrane-bound form of mesothelin cannot be detected in the blood of cancer patients and is not shed by cultured cells into medium (Chang, et al., Cancer Res. 52:181-186 (1992)). In addition to malignant cells, mesothelin is also found on the cell surface of cells of mesothelial origin, including ovarian cancers. Because damage to cells in these tissues would not lead to life-threatening consequences, the presence of mesothelin on the surface of cancer cells makes it a promising candidate for targeted therapies.
Immunotoxins are antibodies directed against cell surface antigens joined to a toxic moiety. In the treatment of cancer, the antibody preferably is directed against a cell surface antigen expresser only on cancer cells. However, if the death of normal cells which also express the surface antigen is not more life-threatening than the existence of the malignancy, antibodies directed against cell surface antigens expressed on non-malignant cells can be used in cancer therapy. The toxic moiety of the immunotoxin can be any toxin that is not harmful to non-targeted cells at low concentrations after systemic administration. Such a toxin is the Pseudomonas aeruginosa exotoxin (PE). Previous studies with PE have demonstrated that the active portion of the protein is composed of domain II and III, both of which are located at the carboxyl end of the toxin.
The antibodies that target the immunotoxin can be polyclonal, monoclonal, or recombinant antibodies, such as chimeras or variable region fragments. If the antibody is non-recombinant, the immunotoxin must be formed by chemical conjugation of the antibody to the toxic moiety. If the antibody is produced recombinantly, the antibody can be joined to the toxin through chemical bonding or through recombinant fusion. In recombinant fusion, cDNA encoding the antibody is inserted, in frame, into a plasmid that already contains cDNA which encodes the toxin. Of course, the reverse could be done as well; the toxin cDNA can be inserted into a plasmid carrying cDNA which encodes the antibody.
Because of the potential large size of the immunotoxin, it is sometimes desired to join only a fragment of an antibody to the toxic moiety. Fab, Fab′ and F(ab)2 fragments can be made from polyclonal, monoclonal and chimeric antibodies and then joined to the toxin through chemical bonding.
Alternatively, a cDNA can be produced in which the variable regions of an antibody are connected to essential framework regions. These smaller antibodies are then secreted as double chain Fv antibodies or, if the heavy and light chain regions are joined either directly or through a peptide linker, as single chain Fv antibodies (scFv).
One method of creating a scFv is through phage display libraries made from splenic mRNA of mice immunized with an immunogen (Chowdhury, et al., Mol. Immunol. 34:9-20 (1997)). However, if a protein immunogen is naturally found in mammals but is recombinantly expressed in prokaryotes, the protein will not have the correct glycosylation pattern and may not have the correct conformation. Antibodies developed by the mouse in response to this immunogen may not recognize the protein in its native state. One solution to this problem is to immunize animals with the native protein made in mammalian cells, but purification from mammalian cells of sufficient amounts of some proteins, in particular cell surface proteins, may not be possible. Another solution, although not as common, is to immunize animals with cDNA which encodes the immunogen. The cDNA, under the control of an appropriate promoter, is introduced into the animal. After boosting injections and when the antibody titer reaches a maximum, the animals are sacrificed and the spleens removed to create the phage display library.
There is a need for better chemotherapeutic agents to control cancers such as ovarian cancer and mesotheliomas, both of which are rarely cured by currently available chemotherapies. The following disclosure describes such a chemotherapeutic agent.

Antibodies, including FV molecules, and immunoconjugates having high binding affinity for mesothelin and methods for their use

The United States of America as represented by the Department of Health and Human Services


A new method of completing a tungsten contact is described. An insulator layer is formed over device structures in and on a semiconductor substrate. The insulator layer is flowed to planarize the layer. The insulator layer is covered with a spin-on-glass layer which is baked and cured. Contact openings are formed through the insulator and spin-on-glass layers to the device structures and to the substrate. A nucleation layer is formed over the spin-on-glass layer and within the contact openings. A layer of tungsten is deposited over the nucleation layer. The tungsten layer is etched back, thereby leaving the tungsten layer within the contact openings and leaving some of the tungsten layer as residue overlying the spin-on-glass layer. The spin-on-glass layer is removed, thereby removing any tungsten layer residue overlying the spin-on-glass layer. The contacts are completed by an aluminum metalization.

(1) Field of the Invention
The invention relates to a method of completing a tungsten contact in an integrated circuit device, and more particularly, to a method of completing a tungsten contact while maintaining underlayer planarity.
(2) Description of the Prior Art
Blanket etchback of tungsten is known. In his book, Chemical Vapor Deposition of Tungsten and Tungsten Silicides (by John E. J. Schmidt, Noyes Publications, Park Ridge, NJ, c. 1992, pp. 43-50), Schmidt describes the etchback of blanket tungsten either with or without a sacrificial layer. The problem of tungsten residue is not addressed.
Referring to FIG. 1, there is shown a portion of a partially completed integrated circuit in which there is a silicon substrate 10. Also shown are dielectric layers 12 and 16 and a polysilicon layer 14. Contact or via opening 17 is shown to a source/drain region 18. A shorter contact or via opening 19 contacts polysilicon layer 14. A layer of tungsten 20 is blanket deposited over all. A barrier or adhesion layer such as titanium nitride may be used under the tungsten layer, but is not illustrated.
FIG. 2 shows the same portion of the integrated circuit after tungsten etchback. There are four problem areas. In area 1 where the slope of the indentation is 40% or more, a residue of tungsten layer 20 remains after etching. In area 2, where the slope is 30% or more, some tungsten residue remains. In area 3, the contact is about 1 micrometer in height. There is a dimple in the tungsten plug. In area 4, where the contact is less than about 0.6 micrometers in height, the plug may have a dimple which goes all the way to the underlying layer. If the tungsten is etched enough to remove the residue in areas 1 and 2, the entire plug is area 4 will be etched away and damage may occur to the underlying layer 14. If tungsten residue exists after the tungsten etchback, leakage will occur from the residue into overlying layers. Overetching to remove the residue results in the loss of the tungsten plug in short via holes. Another drawback of the conventional process is that surface roughness of the tungsten is transferred to the underlayer silicon oxide layer when the tungsten is etched back. Because of this, there is a critical requirement for underlayer planarity necessitating a higher flow temperature for the insulator flow process.
U.S. Pat. No. 5,164,330 to Davis et al describes a method of etching a tungsten layer using nitrogen trifluorid (NF.sub.3) and argon gases to reduce residue buildup.

Blanket tungsten etchback process using disposable spin-on-glass

Industrial Technology Research Institute


A photovoltaic device that comprises an insulating transparent substrate coated with a light-receiving surface electrode formed of a thin metal film which in turn is overlaid with an amorphous semiconductor layer and a back electrode, said thin metal film being adapted for use as a mirror.

A conventional amorphous silicon solar cell system comprises a plurality of unit solar cells that are formed by superposing transparent electrodes, amorphous silicon (a-Si) film regions and back electrodes on a single glass substrate. The individual unit solar cells are connected in series in such a manner that the back electrode of one unit cell contacts the transparent electrode of an adjacent unit cell via a conductive path.
Solar cells are inherently designed to utilize the electric energy directly converted from sunlight and no considerations have been made to adapt solar cells to applications that have nothing to do with this photovoltaic conversion of sunlight to electricity. Since conventional solar cells use tin oxide or indium-tin oxide in transparent electrodes, their reflectance is too low to enable use as mirrors (for the reflectance of SnO.sub.2 as compared to metals, see FIG. 2).
Another problem with the prior art is the difficulty involved in attempts at reducing the cost of materials. Currently, thin films of tin oxide or indiumtin oxide are deposited by a thermal CVD process or sputtering but this requires the use of not only expensive oxide targets but also a complicated sputtering apparatus such as one using a radio-frequency magnetron.


A manufacturing method of a plasma display panel and the plasma display panel made using the manufacturing method include the align marks being maintained in a discernible state. The method for manufacturing a plasma display panel includes forming electrodes on a substrate along one direction, and forming align marks on edges of the substrate, depositing a dielectric paste on the substrate covering the align marks, drying the dielectric paste, and baking the dielectric paste to thereby form a dielectric layer. The align marks are left fully remaining such that they are easily discernible, thereby making sealing and other processes easy.

1. Field of the Invention
The present invention relates to a plasma display panel (PDP) and a method for manufacturing the same. More particularly, the present invention relates to a manufacturing method of a PDP in which align marks are maintained in a discernible state, and to a PDP made using the manufacturing method.
2. Description of the Related Art
A PDP is a display device that realizes the display of images through excitation of phosphors by plasma discharge. That is, predetermined voltages are applied between two electrodes mounted in a discharge region of the PDP to thereby effect plasma discharge therebetween. Ultraviolet rays generated during plasma discharge excite phosphor layers that are formed in a predetermined pattern, thereby realizing the display of images. The different types of PDPs include the AC-PDP, DC-PDP, and hybrid PDP.
A conventional PDP includes a lower substrate and an upper substrate provided opposing one another with a predetermined gap (i.e., discharge gap) therebetween. A plurality of address electrodes are formed on a surface of the lower substrate opposing the upper substrate. The address electrodes are formed in a stripe pattern substantially along the Y direction. A dielectric layer is formed on the lower substrate covering the address electrodes, and a plurality of barrier ribs are formed on the dielectric layer. The barrier ribs define discharge cells, maintain the discharge gap, and prevent crosstalk between the discharge cells. A phosphor layer is formed between each adjacent pair of the barrier ribs covering the dielectric layer therebetween and side walls of the barrier ribs.
Formed on a surface of the upper substrate opposing the lower substrate are a plurality of display electrodes. The display electrodes are formed substantially along the X direction, that is, substantially along a direction perpendicular to the address electrodes. A dielectric layer and an MgO protection layer are formed on the upper substrate covering the display electrodes.
During manufacture of the PDP, align marks are formed and used as reference points in aligning the lower and upper substrates prior to sealing together the same, and in performing an exposure process. An electrode paste is typically used for the formation of the align marks during the formation of bus electrode (i.e., the display electrodes) in the case of the upper substrate, while an electrode paste is typically used for the formation of the align marks during the formation of the address electrodes in the case of the lower substrate. In recent times, however, a laser has been employed to form the align marks.
It is preferable that none of the elements of the PDP (or portions thereof) are positioned over the align marks in order to ensure full visibility of the align marks. Accordingly, a screen mask must be used during manufacture of the dielectric layers that does not leave the align marks exposed in order to ensure that the dielectric paste is not deposited on the align marks.
However, during drying and baking of the dielectric paste, the align marks, which are exposed during these processes, become oxidized and discolored. This makes the align marks unclear, and therefore causes difficulties in the alignment of the lower and upper substrates.

Plasma display panel and manufacturing method thereof


A method and apparatus for preparing a perforated panel for reticulation to a film adhesive. The method includes supporting the perforated panel. The method also includes adhering the film adhesive to the perforated panel without initiating a cure of the film adhesive. The method applies a vacuum to the film adhesive. Next the method will move the perforated panel at a predetermined speed through a reticulation unit. Next the method will soften the film adhesive and finally remove the film adhesive from the perforations by an airflow. The method is generally used for creating acoustic sheet panels for use in many industries.

1. Field of the Invention
The present invention generally relates to applying an adhesive to a panel, and more particularly, relates to applying a film adhesive to an acoustic face sheet for use in the aerospace industry.
2. Description of Related Art
Methods for applying an adhesive to a core of an acoustic face sheet for use in aerospace or other industries, that require sound dampening, have been known for many years. These prior art core reticulation systems, as they are known, have the film adhesive directly reticulated onto the core of the acoustic panels. After reticulation the core is connected to a surface of the acoustic panel and aligned such that the holes or perforations of the acoustic panel align with the holes of the core. The core reticulation system generally has the film adhesive softened and maintained at the softened state on the core by radiant heaters. After the film adhesive is softened on the core it is passed over an air knife in order to remove the film adhesive from the holes of the core material.
Generally, the core has a honeycomb type shape and it is desired to have the adhesive only on the top portions of the core itself and not within the orifices of the honeycomb core. In the prior art system of reticulation the core, after having the film adhesive softened, will pass through a reticulator on a wire rack that slides on rails within the reticulator. Then an air knife will direct compressed air from underneath the core and at a distance of approximately one foot away from the core. This will allow for the adhesive to be blown from around the top of each cell of the honeycomb cell structure thus in theory leaving the cell passages clear and adhesive free. The end product of the prior art core reticulation system is a core that would include film adhesive around the edge of the core cells. However, many of the prior art systems, due to the size difference of the core cells and ply holes, would have the ply holes blocked during bonding which also would lead to adhesive run off which clogs even more of the perforations in the acoustic panels. The acoustic panels generally work by absorbing sound within the perforations or orifices of the acoustic face sheet. If any of these holes are blocked or the adhesive runs off, which can cause blockage in even more holes, then the acoustic absorption ability of the acoustic face sheet is sharply reduced.
The prior art method of core reticulation encounters numerous problems during the reticulation of the core. First, the air knife used to cut or remove the skin adhesive from the core is driven by compressed air that generally includes contaminants that mix with and degrade the adhesive that is left on the ends of the core cells of the core reticulation system. These contaminants will reduce the adhesive force between the core and outer panels or skins of an acoustic face sheet. Any separation of the outer panel of the acoustic member from the core will degrade the noise absorption characteristics of the panel, reduce structural integrity and also create extraneous noise due to any vibration between the loosely connected core and outer panels. Another problem associated with the prior art core reticulation method is that the air surrounding the film adhesive is capable of cooling which leads to tears in the film adhesive on the edge of the core cells. These tears will reduce the effectiveness of the film adhesive, when the film adhesive is aligned with and secured to the panel. Furthermore, if the air cools enough and the air knife is not run at an appropriate pressure the film adhesive will not be removed from over the opening of the cell in the honeycomb core structure thus blocking the acoustic absorption for that cell and reducing the overall effectiveness of the acoustic absorption of the acoustic sheet. The prior art core reticulation method also has problems developing and having uniform fillets along the edge of the honeycomb cells. Furthermore, if the wrong angle is used for the air knife, with relation to the core, a venturi can develop within each individual cell and the fillet would not be properly formed on top of the cell thus causing a reduction in the acoustic absorption capability of any such damaged cell.
The prior art core reticulation method also generally leaves defects within the core reticulation system of greater then twenty percent. Manufacturers want the acoustic sheet panels to be less then ten percent degraded due to unopened or blocked core cells in the honeycomb core of an acoustic sheet. The noise attenuation of the acoustic face sheets is paramount in the design of modem day aerospace vehicles. The more blocked cells in the honeycomb core the less the noise absorption potential for the acoustic panel. These acoustic panels line cockpits, bodies, wings and even containment walls inside an engine, thus reduction of noise is key to the effectiveness of such products.
Therefore, there is a need in the art for a new reticulation method that will directly adhere the film adhesive to the panel instead of the edge of the honeycomb core. There is also a need in the art for a reticulation method that will reduce the amount of contamination and partially block or blocked cells in the acoustic face sheet core cells. Furthermore, there is a need in the art for a low cost method for manufacturing and building acoustic face sheet panels.

Method and apparatus for applying a film adhesive to a perforated panel


The present invention relates to a transimpedance amplifier circuit that includes a linearized differential transimpedance amplifier, a detector, and dynamic current source circuitry, which diverts common mode currents from feedback resistors in the linearized differential transimpedance amplifier to keep the linearized differential transimpedance amplifier in a linear operating range. Magnitudes of the diverted common mode currents from the feedback resistors may be based on a detected magnitude associated with differential input signals that feed the linearized differential transimpedance amplifier. The detector provides a detector output signal to the dynamic current source circuitry based on the detected magnitude associated with the differential input signals, such that the diverted common mode currents are based on the detector output signal. The transimpedance amplifier circuit provides differential output signals that are based on amplifying the differential input signals.

A differential transimpedance amplifier is commonly used to convert a differential input current to a differential output voltage. For example, in a fiber-optics based communications system, photo-diodes in an optical receiver may provide differential output currents based on received optical data. A differential transimpedance amplifier may be coupled to the photo-diodes to convert the differential output currents into differential output voltages. As fiber-optics based communications standards evolve, reach requirements will increase, which will require optical receivers with increased effective sensitivity. Therefore, differential transimpedance amplifiers will be needed with improved noise performance, increased dynamic range, and improved linearity.
Presently, digital limiting differential transimpedance amplifiers are used with 40 Gigabit per second and 100 Gigabit per second optical receivers to support differential phase shift keying (DPSK) and differential quadrature phase shift keying (DQPSK) modulation methods. However, such amplifiers typically have 50 ohm input resistors, which may introduce unacceptable levels of noise in future systems. FIG. 1 shows a differential limiting amplifier 10 according to the prior art. The differential limiting amplifier 10 includes a first input transistor element QI1, a second input transistor element QI2, a first output transistor element QO1, a second output transistor element QO2, a first resistive element R1 coupled between a base of the first input transistor element QI1 and a DC supply bus, a second resistive element R2 coupled between a base of the second input transistor element QI2 and the DC supply bus, a third resistive element R3 coupled between a collector of the first output transistor element QO1 and the DC supply bus, a fourth resistive element R4 coupled between a collector of the second output transistor element QO2 and the DC supply bus, a first current source 12 coupled between an emitter of the first input transistor element QI1 and ground, a second current source 14 coupled between an emitter of the second input transistor element QI2 and ground, and a third current source 16 coupled between an emitter of the first output transistor element QO1 and ground.
The emitter of the first input transistor element QI1 is coupled to a base of the first output transistor element QO1 and the emitter of the second input transistor element QI2 is coupled to a base of the second output transistor element QO2. The emitter of the first output transistor element QO1 is coupled to an emitter of the second output transistor element QO2. Collectors of the first and second input transistor elements QI1, QI2 are coupled to the DC supply bus. A positive-side input signal VINP feeds the base of the first input transistor element QI1 and a negative-side input signal VINN feeds the base of the second input transistor element QI2. The positive-side and negative-side input signals VINP, VINN are normally phase-shifted about 180 degrees from one another and form a differential input signal. The collector of the first output transistor element QO1 provides a positive-side output signal VOUTP and the collector of the second output transistor element QO2 provides a negative-side output signal VOUTN. The positive-side and negative-side output signals VOUTP, VOUTN are normally phase-shifted about 180 degrees from one another and form a differential output signal. A DC supply signal VDCSUP feeds the DC supply bus.
The first and second input transistor elements QI1, QI2 operate as emitter followers that provide voltages at their respective emitters based on voltages at their respective bases. The first and second output transistor elements QO1, QO2, the third and fourth resistive elements R3, R4, and the third current source 16 form a differential amplifier. The bases of the first and second output transistor elements QO1, QO2 are inputs to the differential amplifier; therefore, the emitter voltages of the first and second input transistor elements QI1, QI2 feed the inputs to the differential amplifier. The collectors of the first and second output transistor elements QO1, QO2 are outputs from the differential amplifier that provide the positive-side and negative-side output signals VOUTP, VOUTN, respectively. Since the differential amplifier tends to amplify differential signals and not amplify common mode signals, a voltage difference between the positive-side and negative-side output signals VOUTP, VOUTN is based on a voltage difference between the positive-side and negative-side input signals VINP, VINN.
The differential limiting amplifier 10 may be used as a transimpedance amplifier by converting input currents associated with the positive-side and negative-side input signals VINP, VINN into input voltages by routing most of the input currents into the first and second resistive elements R1, R2. The resulting voltage drop across the first and second resistive elements R1, R2 provides the input voltages. The first and second resistive elements R1, R2 are sized to provide appropriate conversion values. For example, in one application, a value of each of the first and second resistive elements R1, R2 is equal to about 50 ohms, which may be noisy. Since a differential limiting amplifier 10 may be noisy, a differential transimpedance amplifier used as a pre-amplifier stage may reduce noise.
FIG. 2 shows a differential transimpedance amplifier 18 according to the prior art. The differential transimpedance amplifier 18 includes the first input transistor element QI1, the second input transistor element QI2, a first feedback transistor element QF1, a second feedback transistor element QF2, the first resistive element R1 coupled between the collector of the first input transistor element QI1 and a DC supply bus, the second resistive element R2 coupled between the collector of the second input transistor element QI2 and the DC supply bus, the third resistive element R3 coupled between an emitter of the first feedback transistor element QF1 and ground, the fourth resistive element R4 coupled between an emitter of the second feedback transistor element QF2 and ground, the first current source 12 coupled between the emitter of the first input transistor element QI1 and ground, a first feedback resistive element RF1 coupled between the emitter of the first feedback transistor element QF1 and the base of the first input transistor element QI1, and a second feedback resistive element RF2 coupled between the emitter of the second feedback transistor element QF2 and the base of the second input transistor element QI2.
The collector of the first input transistor element QI1 is coupled to a base of the first feedback transistor element QF1 and the collector of the second input transistor element QI2 is coupled to a base of the second feedback transistor element QF2. The emitter of the first input transistor element QI1 is coupled to the emitter of the second input transistor element QI2. Collectors of the first and second feedback transistor elements QF1, QF2 are coupled to the DC supply bus. A positive-side transimpedance input signal VTINP feeds the base of the first input transistor element QI1 and a negative-side transimpedance input signal VTINN feeds the base of the second input transistor element QI2. The positive-side and negative-side transimpedance input signals VTINP, VTINN are normally phase-shifted about 180 degrees from one another and form a differential input signal. The collector of the first input transistor element QI1 provides a positive-side transimpedance output signal VTOUTP and the collector of the second input transistor element QI2 provides a negative-side transimpedance output signal VTOUTN. The positive-side and negative-side transimpedance output signals VTOUTP, VTOUTN are normally phase-shifted about 180 degrees from one another and form a differential output signal. The DC supply signal VDCSUP feeds the DC supply bus.
The first and second input transistor elements QI1, QI2, the first and second resistive elements R1, R2, and the first current source 12 form a differential amplifier. The bases of the first and second input transistor elements QI1, QI2 are inputs to the differential amplifier, and the collectors of the first and second input transistor elements QI1, QI2 are outputs from the differential amplifier. The first and second feedback transistor elements QF1, QF2, the third and fourth resistive elements R3, R4, and the first and second feedback resistive elements RF1, RF2 form a feedback circuit that provides feedback from the outputs of the differential amplifier back to the inputs of the differential amplifier. Therefore, the differential transimpedance amplifier 18 may operate as a differential amplifier with differential feedback.
Since the differential transimpedance amplifier 18 is a transimpedance amplifier, which is commonly used to convert a differential input current to a differential output voltage, the positive-side and negative-side transimpedance input signals VTINP, VTINN are normally associated with positive-side and negative-side transimpedance input currents ITINP, ITINN, respectively. Most of the positive-side and negative-side transimpedance input currents ITINP, ITINN may flow through the first and second feedback resistive elements RF1, RF2, respectively. The first and second feedback resistive elements RF1, RF2 have positive-side and negative-side feedback currents IFP, IFN, respectively, which may be slightly less than the positive-side and negative-side transimpedance input currents ITINP, ITINN. The positive-side and negative-side feedback currents IFP, IFN and currents from the emitters of the first and second feedback transistor elements QF1, QF2 combine to feed the third and fourth resistive elements R3, R4, respectively, which have third and fourth resistive currents IR3, IR4, respectively. Most of the positive-side transimpedance input current ITINP, all of the positive-side feedback current IFP, and a portion of the third resistive current IR3 may follow a positive-side current path IPATHP. Similarly, most of the negative-side transimpedance input current ITINN, all of the negative-side feedback current IFN, and a portion of the fourth resistive current IR4 may follow a negative-side current path IPATHN.
Since the differential transimpedance amplifier 18 may operate as a differential amplifier with differential feedback, a voltage difference between the positive-side and negative-side transimpedance output signals VTOUTP, VTOUTN may be based on a current difference between the positive-side and negative-side transimpedance input currents ITINP, ITINN.
Use of the differential transimpedance amplifier 18 as a pre-amplifier stage may reduce noise compared to a differential limiting amplifier 10, but may be at the expense of linearity and dynamic range. Future optical communications systems may require linear operation to support advanced features, such as coherent detection and digital signal processing, which may be associated with electronic dispersion compensation (EDC). Thus, there is a need for a differential transimpedance amplifier which may be used as a pre-amplifier stage, is linear, has wide dynamic range, and has low noise.

Linearized differential transimpedance amplifier