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).

  • Patent number: 6683646
    Abstract: 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: Grant
    Filed: November 24, 1997
    Date of Patent: January 27, 2004
    Assignee: Xerox Corporation
    Inventors: Paul A. Hosier, Scott L. Tewinkle, Jagdish C. Tandon
  • Patent number: 6654056
    Abstract: 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: Grant
    Filed: December 15, 1998
    Date of Patent: November 25, 2003
    Assignee: Xerox Corporation
    Inventors: Alain E. Perregaux, Jagdish C. Tandon, Paul A. Hosier, Roger L. Triplett, Xiao-Fan Feng
  • Patent number: 6650416
    Abstract: 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: Grant
    Filed: December 4, 2002
    Date of Patent: November 18, 2003
    Assignee: Xerox Corporation
    Inventors: Jagdish C. Tandon, Lingappa K. Mestha, Fred F. Hubble, III
  • Patent number: 6646248
    Abstract: 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: Grant
    Filed: April 24, 2001
    Date of Patent: November 11, 2003
    Assignee: Xerox Corporation
    Inventors: Paul A. Hosier, Jagdish C. Tandon, Josef E. Jedlicka, Gaurav Sharma, Alain E. Perregaux, Robert P. Herloski
  • Patent number: 6646247
    Abstract: 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: Grant
    Filed: March 22, 2001
    Date of Patent: November 11, 2003
    Assignee: Xerox Corporation
    Inventors: Paul A. Hosier, Jagdish C. Tandon
  • Patent number: 6642964
    Abstract: 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: Grant
    Filed: December 15, 1998
    Date of Patent: November 4, 2003
    Assignee: Xerox Corporation
    Inventors: Alain E. Perregaux, Jagdish C. Tandon, Roger L. Triplett, Xiao-Fan Feng
  • Publication number: 20030194864
    Abstract: 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: Application
    Filed: November 30, 2001
    Publication date: October 16, 2003
    Applicant: Xerox Corporation.
    Inventors: Alain E. Perregaux, Paul A. Hosier, Josef E. Jedlicka, Nicholas J. Salatino, Jagdish C. Tandon
  • Patent number: 6621576
    Abstract: 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: Grant
    Filed: May 22, 2001
    Date of Patent: September 16, 2003
    Assignee: Xerox Corporation
    Inventors: Jagdish C. Tandon, Lingappa K. Mestha
  • Publication number: 20030132982
    Abstract: 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: Application
    Filed: February 28, 2003
    Publication date: July 17, 2003
    Applicant: Xerox Corporation
    Inventors: Jagdish C. Tandon, Lingappa K. Mestha
  • Patent number: 6567170
    Abstract: 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: Grant
    Filed: June 25, 2001
    Date of Patent: May 20, 2003
    Assignee: Xerox Corporation
    Inventors: Jagdish C. Tandon, Lingappa K. Mestha
  • Publication number: 20030086090
    Abstract: 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: Application
    Filed: December 4, 2002
    Publication date: May 8, 2003
    Applicant: Xerox Corporation
    Inventors: Jagdish C. Tandon, Lingappa K. Mestha, Fred F. Hubble
  • Patent number: 6556300
    Abstract: 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: Grant
    Filed: May 22, 2001
    Date of Patent: April 29, 2003
    Assignee: Xerox Corporation
    Inventors: Jagdish C. Tandon, Lingappa K. Mestha, Fred F. Hubble, III
  • Patent number: 6528336
    Abstract: 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: Grant
    Filed: April 9, 2001
    Date of Patent: March 4, 2003
    Assignee: Xerox Corporation
    Inventors: Paul A. Hosier, Jagdish C. Tandon
  • Publication number: 20030007154
    Abstract: 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: Application
    Filed: June 25, 2001
    Publication date: January 9, 2003
    Applicant: Xerox Corporation
    Inventors: Jagdish C. Tandon, Lingappa K. Mestha
  • Publication number: 20030008423
    Abstract: 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: Application
    Filed: April 9, 2001
    Publication date: January 9, 2003
    Applicant: Xerox Corporation
    Inventors: Paul A. Hosier, Jagdish C. Tandon
  • Publication number: 20020196437
    Abstract: 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: Application
    Filed: May 22, 2001
    Publication date: December 26, 2002
    Applicant: Xerox Corporation
    Inventors: Jagdish C. Tandon, Lingappa K. Mestha, Fred F. Hubble
  • Publication number: 20020191183
    Abstract: 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: Application
    Filed: May 22, 2001
    Publication date: December 19, 2002
    Applicant: Xerox Corporation
    Inventors: Jagdish C. Tandon, Lingappa K. Mestha
  • Publication number: 20020181033
    Abstract: 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: Application
    Filed: May 29, 2001
    Publication date: December 5, 2002
    Applicant: Xerox Corporation
    Inventors: Jagdish C. Tandon, Keith T. Knox, Robert R. Buckley
  • Publication number: 20020153471
    Abstract: 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: Application
    Filed: April 24, 2001
    Publication date: October 24, 2002
    Applicant: Xerox Corporation
    Inventors: Paul A. Hosier, Jagdish C. Tandon, Josef E. Jedlicka, Gauray Sharma, Alain E. Perregaux, Robert P. Herloski
  • Publication number: 20020134913
    Abstract: 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: Application
    Filed: March 22, 2001
    Publication date: September 26, 2002
    Applicant: Xerox Corporation
    Inventors: Paul A. Hosier, Jagdish C. Tandon