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USING CHARGE INJECTION ON CCD IMAGING CHIPS

IP.com Disclosure Number: IPCOM000024489D
Original Publication Date: 1980-Oct-31
Included in the Prior Art Database: 2004-Apr-02
Document File: 2 page(s) / 55K

Publishing Venue

Xerox Disclosure Journal

Abstract

Most present day Charge Coupled Devices (CCD) have a charge injection input for testing the CCD. If both the CCD charge injection input and the photodiode inputs are used simultaneously, the charges will add and the output of the CCD will be the. sum of the charge representing the photodiode input and the charge injection input. Two uses for this property of the CCD are'envisioned.

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XEROX DISCLOSURE JOURNAL

USING CHARGE INJECTION ON CCD ~ IMAGING CHIPS
Sidney Marshall

Proposed Classification
U.S. C1. 358/212 Int. Cl. H04n 3/12

Most present day Charge Coupled Devices (CCD) have a charge injection input for testing the CCD. If both the CCD charge injection input and the photodiode inputs are used simultaneously, the charges will add and the output of the CCD will be the. sum of the charge representing the photodiode input and the charge injection input. Two uses for this property of the CCD are'envisioned.

If it is desired to screen an image being scanned by the CCD with an additive screen, then the screen values could be inserted via the charge injection input and the output of the CCD thresholded at a fixed level. This would provide screened image data with only minimal circuitry.

Secondly, there is a variation from cell to cell of the CCD due to dark current, and this variation appears at the output of the CCD as an additive error. If this error is stored in a storage device of some sort (either analog or digital) then the dark current error can be compensated for by injecting a signal opposite to the dark current characteristics of the cells through the charge injection input. The output of the CCD will then be free of additive cell to cell errors.

Volume 5 Number 5 September/October 1980 545

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546

    XEROX DISCLOSURE JOURNAL Volume 5 Number 5 September/October 1980

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