ARRAY BASED SENSOR TO MEASURE SINGLE SEPARATION OR MIXED COLOR (OR IOI) PATCHES ON THE PHOTORECEPTOR USING MEMS BASED HYPERSPECTRAL IMAGING TECHNOLOGY

• US 20080080027A1
• Filed: 09/26/2006
• Published: 04/03/2008
• Est. Priority Date: 09/26/2006
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Mestha, Lalit K., Wang, Yao Rong, Lin, Pinyen, Gulvin, Peter M.
• Granted Patent: US 7,583,418 B2
• Time in Patent Office: Days
• US Class Current: 358/504
• CPC Class Codes: G01J 1/4223 specially adapted for copy - or printing apparatus
• CPC Class Codes: G01J 3/02 Details
• CPC Class Codes: G01J 3/0256 Compact construction
• CPC Class Codes: G01J 3/0264 Electrical interface; User interface
• CPC Class Codes: G01J 3/0291 Housings; Spectrometer accessories; Spatial arrangement of elements, e.g. folded path arrangements
• CPC Class Codes: G01J 3/26 using multiple reflection, e.g. Fabry-Perot interferometer, variable interference filters
• CPC Class Codes: G01J 3/2803 using photoelectric array detector
• CPC Class Codes: G01J 3/36 Investigating two or more bands of a spectrum by separate detectors
• CPC Class Codes: G01J 3/50 using electric radiation detectors
• CPC Class Codes: G01J 3/51 using colour filters
• CPC Class Codes: G01J 3/513 having fixed filter-detector pairs
• CPC Class Codes: G01J 3/52 using colour charts
• CPC Class Codes: G01J 3/524 Calibration of colorimeters
• CPC Class Codes: H04N 1/46 Colour picture communication systems
• CPC Class Codes: H04N 1/6033 using test pattern analysis H04N1/6055 takes precedence

Abstract

A Micro-Electro-Mechanical System (MEMS) based Fabry-Perot array may be used as a spectral filter to light sensing array, such as a CCD or CMOS photodetector. Applying different voltages to the electrodes of individual Fabry-Perot cells within the array allows a gradient in the Fabry-Perot air gap across the Fabry-Perot array. In this manner the MEMS Fabry-Perot array serves as a spectral filter of light passing through the Fabry-Perot array to the photodetector array. Embodiments of the disclosed sensor, used with LEDs that emit light outside the photosensitivity range of a photoreceptor belt, may be used to measure spectral information from toned patches and/or images placed upon a photoreceptor belt within a marking system. Other embodiments of the disclosed senor, used with LEDs that emit light of any wavelength, may be used to measure spectral information from toned patches or images placed by a marking system upon a non-photosensitive output substrate, such as an intermediate belt or paper.

Claims

1. A method of calibrating a marking engine that includes a photoreceptor transfer device having at least a first area on a surface of the photoreceptor transfer device, the at least first area receiving at least one color of marking material that is a portion of an image, the photoreceptor transfer device conveying the marking material to at least one of another transfer device or an output substrate, the method comprising:

configuring Fabry-Perot cells within a Fabry-Perot array to form a desired light filter pattern;

disposing at least one toned patch in a second area of the photoreceptor transfer device, the second area being a margin area located on the surface of the photoreceptor transfer device; and

illuminating the disposed toned patch or image on the photoreceptor transfer device;

filtering light reflected from the toned patch or image through the Fabry-Perot array;

measuring the filtered light received from different Fabry-Perot cells within the Fabry-Perot array to obtain measured spectral information values for the toned patch or image in response to the illumination; and

performing a color calibration for use in a marking operation based on the measured spectral information values.

2. The method of claim 1, wherein configuring Fabry-Perot cells into a desired light filter pattern comprises setting Fabry-Perot cells within the Fabry-Perot array with a desired cell gap.

3. The method of claim 1, wherein configuring Fabry-Perot cells into a desired light filter pattern comprises setting Fabry-Perot cells within the Fabry-Perot array so that the cell gaps across the array in selected direction form a desired slope.

4. The method of claim 1, wherein configuring Fabry-Perot cells into a desired light filter pattern comprises setting a subset of the Fabry-Perot cells within the Fabry-Perot array to a common gap width.

5. The method of claim 1, wherein configuring Fabry-Perot cells into a desired light filter pattern comprises setting Fabry-Perot cells within the Fabry-Perot array based upon marking material in the first area or a toned patch in the second area.

6. The method of claim 1, wherein configuring Fabry-Perot cells into a desired light filter pattern comprises setting Fabry-Perot cells within the Fabry-Perot array in a fixed, immovable configuration.

7. The method of claim 1, wherein disposing the at least one toned patch comprises:

retrieving a stored toned patch pattern stored in a memory device for at least one toned patch; and

disposing the at least one toned patch on the photoreceptor transfer device based upon the retrieved toned patch pattern.

8. The method of claim 7, wherein disposing the at least one toned patch further comprises disposing at least one toned patch separately from each primary color used by the marking engine.

9. The method of claim 1, wherein the at least one toned patch comprises at least one of a single-color patch, a mixed-color patch, or a multi-separation image-on-image color patch.

10. The method of claim 1, wherein illuminating the at least one toned patch comprises illuminating the at least one toned patch with an illumination wavelength outside the photo response range of the photoreceptor transfer device.

11. The method of claim 10, wherein illuminating the at least one toned patch with an illumination wavelength outside the photo response range of the photoreceptor transfer device includes, selecting an illumination source that emits illumination at a wavelength for which the photoreceptor generates a number of electron-hole pairs below a predetermined threshold determined for the photoreceptor transfer device.

12. The method of claim 11, wherein the predetermined threshold may be any value below which ghosting is not observed in subsequent toned patches or output image pitches.

13. The method of claim 1, wherein performing the calibration comprises:

determining a tone reproduction curve for a pitch based on the measured spectral information values; and

applying the tone reproduction curves to the respective pitch.

14. A system comprising:

a photoreceptor transfer device that includes a plurality of first areas receiving at least one color of marking material that is a portion of an image and conveying the marking material to one of another transfer device or to an output substrate;

a first storage device adapted to store a toned patch pattern for a toned patch;

a marking engine that marks a desired image and marks a toned patch in a second area of the photoreceptor transfer device based on the stored toned patch pattern, at least one illumination source that illuminates a toned patch or image on the photoreceptor transfer device with an illumination wavelength;

a Fabry-Perot array sensor that measures spectral information for a toned patch or image illuminated on the photoreceptor transfer device to obtain spectral information values for the toned patch or image in response to illumination of the toned patch from the at least one illumination source; and

a calibration processor that performs a color calibration for use in a marking operation based on the measured reflectance value.

15. The system of claim 14, wherein the calibration processor determines at least one tone reproduction curve based on the spectral information values.

16. The system of claim 14, wherein the at least one illumination source illuminates a toned patch with an illumination wavelength outside the photo response range of the photoreceptor transfer device.

17. The system of claim 16, wherein the at least one illumination source selects an illumination source that emits illumination at a wavelength for which the photoreceptor generates a number of electron-hole pairs below a predetermined threshold determined for the photoreceptor transfer device.

18. The system of claim 17, wherein the predetermined threshold may be any value below which ghosting is not observed in subsequent toned patches or output image pitches.

19. The system of claim 14, the Fabry-Perot array sensor further comprising:

an illumination controller that controls illumination of the at least one illumination source.

20. The system of claim 14, the Fabry-Perot array sensor further comprising a light sensing array that measures filtered light received from Fabry-Perot cells within the Fabry-Perot array to obtain measured spectral information values for the toned patch in response to the illumination.

21. The system of claim 14, wherein Fabry-Perot cells within the Fabry-Perot array are set in a fixed, immovable configuration.

22. The system of claim 14, the Fabry-Perot array sensor further comprising a reconfiguration controller that configures Fabry-Perot cells within a Fabry-Perot array to form a desired light filter pattern.

23. The system of claim 22, wherein the reconfiguration controller configures Fabry-Perot cells within the Fabry-Perot array into a desired light filter pattern based upon marking material in at least one of the plurality of first areas or the second area.

24. The system of claim 14, the Fabry-Perot array sensor further comprising a spectral filtering controller that provides spectral information to a marking system controller based upon measured spectral values received from a light sensing array and Fabry-Perot array filter configuration information received from a reconfiguration controller.

25. An image forming device comprising the system of claim 14.

26. A xerographic image forming device comprising the system of claim 14.