Patents by Inventor Jagdish C. Tandon
Jagdish C. Tandon has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).
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Patent number: 6683646Abstract: A CMOS-based photosensor array, having a plurality of photodiodes therein, includes a spillover protection circuit associated with each photodiode. The spillover protection circuit causes a potential to be applied to a photodiode in response to a charge spillover or “blooming” condition. The spillover protection device is momentarily disabled whenever a bias charge is injected onto the photodiode by the transfer circuit. Also, a reference voltage applied to the gate of a transistor forming the spillover protection device is higher than a threshold voltage of the transistor but is lower than a sum of the threshold voltage and a maximum light-intensity signal from the photodiode.Type: GrantFiled: November 24, 1997Date of Patent: January 27, 2004Assignee: Xerox CorporationInventors: Paul A. Hosier, Scott L. Tewinkle, Jagdish C. Tandon
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Patent number: 6654056Abstract: Geometric configurations for photosites found on photosensitive chips for creating electrical signals from an original image, as would be found, for example, in a digital scanner, copier, facsimile machine, or other document generating or reproducing device. The photosensitive chips are mounted on a substrate to form a photosensitive array in a full width scanner or other photosensitive device. The geometric configurations reduce the Moiré patterns to provide a higher quality image.Type: GrantFiled: December 15, 1998Date of Patent: November 25, 2003Assignee: Xerox CorporationInventors: Alain E. Perregaux, Jagdish C. Tandon, Paul A. Hosier, Roger L. Triplett, Xiao-Fan Feng
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Patent number: 6650416Abstract: A color spectrophotometer incorporating a low cost commercial imaging chip, which normally forms part of a document imaging bar used for imaging documents in scanners, etc., having multiple photo-sites with three different rows of color filters. Each chip is mounted on the optical axis of an imaging lens system, in the image plane of that lens system, to image the reflected illumination from an illuminated color test target area on the chip. The optical axis of the imaging lens system is oriented at 45° to the illuminated color test patches, and the photodetector chip is physically mounted perpendicular to the plane of the illuminated color test patches. Respective photo-sensor chips and associated 1:1 optics may be mounted on opposing sides of the spectrophotometer physically oriented at 90° to the test target area plane receiving the reflected light from the test target optically oriented at 45° to the illuminated test target.Type: GrantFiled: December 4, 2002Date of Patent: November 18, 2003Assignee: Xerox CorporationInventors: Jagdish C. Tandon, Lingappa K. Mestha, Fred F. Hubble, III
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Patent number: 6646248Abstract: A photosensitive imaging device for recording images across the entire visible spectrum includes a set of photosensors which have a peak response around the orange part of the spectrum, about 600 nm. The peak response is obtained by combining responses of, in one case, photosensors associated with a filter which admits red or infrared wavelengths and longer and photosensors associated with a filter which admits orange wavelengths and longer. In another case, the photosensor is structured to attenuate longer wavelengths, which, in combination with a filter which admits orange and longer wavelengths, can simulate a peak behavior around the orange part of the spectrum.Type: GrantFiled: April 24, 2001Date of Patent: November 11, 2003Assignee: Xerox CorporationInventors: Paul A. Hosier, Jagdish C. Tandon, Josef E. Jedlicka, Gaurav Sharma, Alain E. Perregaux, Robert P. Herloski
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Patent number: 6646247Abstract: In a photosensitive device wherein a photodiode is operated by placing an initial fat zero charge thereon before the integration of a light-induced signal, the actual dark level signal created by the fat zero charge is sampled with each readout from the photodiode, and then retransferred to the photodiode. After integration, the sampled dark level is subtracted from the total signal level on the photodiode. In this way both fixed-pattern and thermally-induced noise is obviated.Type: GrantFiled: March 22, 2001Date of Patent: November 11, 2003Assignee: Xerox CorporationInventors: Paul A. Hosier, Jagdish C. Tandon
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Patent number: 6642964Abstract: Geometric configurations for photosites found on photosensitive chips for creating electrical signals from an original image, as would be found, for example, in a digital scanner, copier, printer, facsimile machine, or other document generating or reproducing device. The photosensitive chips are mounted on a substrate to form a photosensitive array in a full width scanner or other photosensitive device. The geometric configurations reduce the Moiré patterns to provide a higher quality image.Type: GrantFiled: December 15, 1998Date of Patent: November 4, 2003Assignee: Xerox CorporationInventors: Alain E. Perregaux, Jagdish C. Tandon, Roger L. Triplett, Xiao-Fan Feng
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Publication number: 20030194864Abstract: The present disclosure relates that by modifying chip die dicing methodology to a U-groove profile from a V-groove profile by modifying the second etch step to be a dry etch instead of a wet etch results in a direct cost savings by eliminating a more expensive process step, as well as the need for stripping the developed photoresist layer. Furthermore, going to a U-groove profile accomplishes additional indirect and greater cost savings resulting from increased process throughput, improved yield, and reduced metal layer defects.Type: ApplicationFiled: November 30, 2001Publication date: October 16, 2003Applicant: Xerox Corporation.Inventors: Alain E. Perregaux, Paul A. Hosier, Josef E. Jedlicka, Nicholas J. Salatino, Jagdish C. Tandon
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Patent number: 6621576Abstract: An improved and lower cost color spectrophotometer, especially suitable for on-line color printer color control systems, incorporating a low cost commercial imaging chip, which normally only forms part of a three row, three color, document imaging bar used for imaging documents in scanners, digital copiers, or multifunction products, having multiple photo-sites with at least three different color filters in three rows. This multiple photo-sites chip may be modified to also provide unfiltered photo-sites. This spectrophotometer may have a substantially reduced number of different LED or other spectral illumination sources, one of which may be for white light, yet provide multiple spectral data outputs from the differently filtered photo-sites being simultaneous illuminated by the light reflected from a color test target area which is being sequentially illuminated by the respective limited number of LEDs, enabling broad spectrum information and color control.Type: GrantFiled: May 22, 2001Date of Patent: September 16, 2003Assignee: Xerox CorporationInventors: Jagdish C. Tandon, Lingappa K. Mestha
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Publication number: 20030132982Abstract: An improved and lower cost color spectrophotometer, especially suitable for on-line color printer color control systems, incorporating a low cost commercial imaging chip, which normally only forms part of a three row, three color, document imaging bar used for imaging documents in scanners, digital copiers, or multifunction products, having multiple photo-sites with at least three different color filters in three rows. This multiple photo-sites chip may be modified to also provide unfiltered photo-sites. This spectrophotometer may have a substantially reduced number of different LED or other spectral illumination sources, one of which may be for white light, yet provide multiple spectral data outputs from the differently filtered photo-sites being simultaneous illuminated by the light reflected from a color test target area which is being sequentially illuminated by the respective limited number of LEDs, enabling broad spectrum information and color control.Type: ApplicationFiled: February 28, 2003Publication date: July 17, 2003Applicant: Xerox CorporationInventors: Jagdish C. Tandon, Lingappa K. Mestha
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Patent number: 6567170Abstract: A low cost yet higher speed color spectrophotometer, especially suitable for on-line color printer color control systems, wherein multiple test patches of different colors may be simultaneously illuminated and substantially simultaneously discretely color analyzed. Reduced numbers of test print sheets, with multiple sets of multiple small adjacent different color test patches, may be used. Reflected images of the multiple different color test patches may be simultaneously focused on different areas of a photodetector chip to expose differently color responsive sets of multiple photo-sites to provide plural discrete color signals for each different color test patch image.Type: GrantFiled: June 25, 2001Date of Patent: May 20, 2003Assignee: Xerox CorporationInventors: Jagdish C. Tandon, Lingappa K. Mestha
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Publication number: 20030086090Abstract: A color spectrophotometer incorporating a low cost commercial imaging chip, which normally forms part of a document imaging bar used for imaging documents in scanners, etc., having multiple photo-sites with three different rows of color filters. Each chip is mounted on the optical axis of an imaging lens system, in the image plane of that lens system, to image the reflected illumination from an illuminated color test target area on the chip. The optical axis of the imaging lens system is oriented at 45° to the illuminated color test patches, and the photodetector chip is physically mounted perpendicular to the plane of the illuminated color test patches. Respective photo-sensor chips and associated 1:1 optics may be mounted on opposing sides of the spectrophotometer physically oriented at 90° to the test target area plane receiving the reflected light from the test target optically oriented at 45° to the illuminated test target.Type: ApplicationFiled: December 4, 2002Publication date: May 8, 2003Applicant: Xerox CorporationInventors: Jagdish C. Tandon, Lingappa K. Mestha, Fred F. Hubble
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Patent number: 6556300Abstract: A color spectrophotometer incorporating a low cost commercial imaging chip, which normally forms part of a document imaging bar used for imaging documents in scanners, etc., having multiple photo-sites with three different rows of color filters. Each chip is mounted on the optical axis of an imaging lens system, in the image plane of that lens system, to image the reflected illumination from an illuminated color test target area on the chip. The optical axis of the imaging lens system is oriented at 45° to the illuminated color test patches, and the photodetector chip is physically mounted perpendicular to the plane of the illuminated color test patches. Respective photo-sensor chips and associated 1:1 optics may be mounted on opposing sides of the spectrophotometer physically oriented at 90° to the test target area plane receiving the reflected light from the test target optically oriented at 45° to the illuminated test target.Type: GrantFiled: May 22, 2001Date of Patent: April 29, 2003Assignee: Xerox CorporationInventors: Jagdish C. Tandon, Lingappa K. Mestha, Fred F. Hubble, III
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Patent number: 6528336Abstract: A method of fabricating and a wafer having a plurality of photosensor Arrays thereon. And, a method of testing the wafer before the wafer is diced and assembled to form a Silicon photosensor Array which may be combined with other like photosensor arrays to form a full page width image sensor bar. The invention allows checking of every V-groove on every chip. An implanted or diffused region is placed across the V-groove, with electrical connections on both ends of the diffusion. If the V-groove is formed, the diffused region will be broken and the electrical path will be open. A deeper diffusion can be also used to check for incomplete V-grooves. If one end of the electrical path is tied to an existing I/O pad on the chip and the other end to ground, this path will have no effect on the input resistance if the V-groove is formed. There will be a small, but acceptable, increase in input capacitance.Type: GrantFiled: April 9, 2001Date of Patent: March 4, 2003Assignee: Xerox CorporationInventors: Paul A. Hosier, Jagdish C. Tandon
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Publication number: 20030007154Abstract: A low cost yet higher speed color spectrophotometer, especially suitable for on-line color printer color control systems, wherein multiple test patches of different colors may be simultaneously illuminated and substantially simultaneously discretely color analyzed. Reduced numbers of test print sheets, with multiple sets of multiple small adjacent different color test patches, may be used. Reflected images of the multiple different color test patches may be simultaneously focused on different areas of a photodetector chip to expose differently color responsive sets of multiple photo-sites to provide plural discrete color signals for each different color test patch image.Type: ApplicationFiled: June 25, 2001Publication date: January 9, 2003Applicant: Xerox CorporationInventors: Jagdish C. Tandon, Lingappa K. Mestha
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Publication number: 20030008423Abstract: A method of fabricating and a wafer having a plurality of photosensor Arrays thereon. And, a method of testing the wafer before the wafer is diced and assembled to form a Silicon photosensor Array which may be combined with other like photosensor arrays to form a full page width image sensor bar. The invention allows checking of every V-groove on every chip. An implanted or diffused region is placed across the V-groove, with electrical connections on both ends of the diffusion. If the V-groove is formed, the diffused region will be broken and the electrical path will be open. A deeper diffusion can be also used to check for incomplete V-grooves. If one end of the electrical path is tied to an existing I/O pad on the chip and the other end to ground, this path will have no effect on the input resistance if the V-groove is formed. There will be a small, but acceptable, increase in input capacitance.Type: ApplicationFiled: April 9, 2001Publication date: January 9, 2003Applicant: Xerox CorporationInventors: Paul A. Hosier, Jagdish C. Tandon
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Publication number: 20020196437Abstract: A color spectrophotometer incorporating a low cost commercial imaging chip, which normally forms part of a document imaging bar used for imaging documents in scanners, etc., having multiple photo-sites with three different rows of color filters. Each chip is mounted on the optical axis of an imaging lens system, in the image plane of that lens system, to image the reflected illumination from an illuminated color test target area on the chip. The optical axis of the imaging lens system is oriented at 45° to the illuminated color test patches, and the photodetector chip is physically mounted perpendicular to the plane of the illuminated color test patches. Respective photo-sensor chips and associated 1:1 optics may be mounted on opposing sides of the spectrophotometer physically oriented at 90° to the test target area plane receiving the reflected light from the test target optically oriented at 45° to the illuminated test target.Type: ApplicationFiled: May 22, 2001Publication date: December 26, 2002Applicant: Xerox CorporationInventors: Jagdish C. Tandon, Lingappa K. Mestha, Fred F. Hubble
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Publication number: 20020191183Abstract: An improved and lower cost color spectrophotometer, especially suitable for on-line color printer color control systems, incorporating a low cost commercial imaging chip, which normally only forms part of a three row, three color, document imaging bar used for imaging documents in scanners, digital copiers, or multifunction products, having multiple photo-sites with at least three different color filters in three rows. This multiple photo-sites chip may be modified to also provide unfiltered photo-sites. This spectrophotometer may have a substantially reduced number of different LED or other spectral illumination sources, one of which may be for white light, yet provide multiple spectral data outputs from the differently filtered photo-sites being simultaneous illuminated by the light reflected from a color test target area which is being sequentially illuminated by the respective limited number of LEDs, enabling broad spectrum information and color control.Type: ApplicationFiled: May 22, 2001Publication date: December 19, 2002Applicant: Xerox CorporationInventors: Jagdish C. Tandon, Lingappa K. Mestha
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Publication number: 20020181033Abstract: In an imaging apparatus such as a scanner or digital camera, a photosensitive device includes multiple linear arrays of photosensors. One of the arrays has a higher spatial resolution than other arrays. The high-resolution array is filtered to detect different portions of the color spectrum than the low-resolution arrays.Type: ApplicationFiled: May 29, 2001Publication date: December 5, 2002Applicant: Xerox CorporationInventors: Jagdish C. Tandon, Keith T. Knox, Robert R. Buckley
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Publication number: 20020153471Abstract: A photosensitive imaging device for recording images across the entire visible spectrum includes a set of photosensors which have a peak response around the orange part of the spectrum, about 600 nm. The peak response is obtained by combining responses of, in one case, photosensors associated with a filter which admits red or infrared wavelengths and longer and photosensors associated with a filter which admits orange wavelengths and longer. In another case, the photosensor is structured to attenuate longer wavelengths, which, in combination with a filter which admits orange and longer wavelengths, can simulate a peak behavior around the orange part of the spectrum.Type: ApplicationFiled: April 24, 2001Publication date: October 24, 2002Applicant: Xerox CorporationInventors: Paul A. Hosier, Jagdish C. Tandon, Josef E. Jedlicka, Gauray Sharma, Alain E. Perregaux, Robert P. Herloski
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Publication number: 20020134913Abstract: In a photosensitive device wherein a photodiode is operated by placing an initial fat zero charge thereon before the integration of a light-induced signal, the actual dark level signal created by the fat zero charge is sampled with each readout from the photodiode, and then retransferred to the photodiode. After integration, the sampled dark level is subtracted from the total signal level on the photodiode. In this way both fixed-pattern and thermally-induced noise is obviated.Type: ApplicationFiled: March 22, 2001Publication date: September 26, 2002Applicant: Xerox CorporationInventors: Paul A. Hosier, Jagdish C. Tandon