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公开(公告)号：CA1240754A
公开(公告)日：1988-08-16
申请号：CA491274
申请日：1985-09-20
Applicant: XEROX CORP
Inventor： HUBBLE FRED F III , BULLOCK RANDOLPH A , CHEUNG LI-FUNG , CRUMRINE ROBERT E , MARTIN JAMES P , WHITE PETER P , ZOMORRODI MEHRDAD
Abstract: The present invention is concerned with a self-adjusting document sensor compensating for degradation of the sensor system. A suitable light source and a detector are provided, the output of the detector being fed into an amplifier whose gain depends upon a feedback signal. Periodically, the output of the amplifier is compared to a reference. If the output of the amplifier falls below the reference, a pulse is sent to a ripple counter whose digital output is fed back to the amplifier to change the gain of the amplifier.If the detector is an unbiased photodiode operating in the transconductance mode, the leakage currents and their subsequent effect on output with amplifier gain changes will be minimized.
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公开(公告)号：GB2165045B
公开(公告)日：1988-10-26
申请号：GB8523844
申请日：1985-09-27
Applicant: XEROX CORP
Inventor： HUBBLE III FRED F , BULLOCK RANDOLPH A , CHEUNG LI-FUNG , CRUMRINE ROBERT E , MARTIN JAMES P , WHITE PETER P , ZOMORRODI MEHRDAD
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公开(公告)号：GB2165045A
公开(公告)日：1986-04-03
申请号：GB8523844
申请日：1985-09-27
Applicant: XEROX CORP
Inventor： HUBBLE III FRED F , BULLOCK RANDOLPH A , CHEUNG LI-FUNG , CRUMRINE ROBERT E , MARTIN JAMES P , WHITE PETER P , ZOMORRODI MEHRDAD
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