Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1990-11-26
1993-05-25
Coles, Sr., Edward L.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358443, 358464, H04N 140
Patent
active
052145204
ABSTRACT:
An image data reading apparatus is provided, comprising a transport part for transporting an original sheet to a reading position within the image data reading apparatus, a white reference plate provided at the reading position, a light source for generating a light projected to the reading position, a light receiving part for converting an incoming light reflected from the white reference plate into a white reference signal and for converting an incoming light reflected from the original sheet into an image signal, a correction part for eliminating a shading from the image signal based on a reference voltage, a peak level holding part for detecting and storing a peak level of a corrected signal from the correction part, a quantization part for converting an incoming signal from the correction part into digital information based on the peak level, and a switching part for turning the peak level holding part off to stop detection and storing of the peak level of the incoming signal for a prescribed time period between a time the white reference signal is received by the light receiving part from the white reference plate and at a time the original sheet is transported to the reading position, so that the peak level holding part receives no signal from the light receiving part during the prescribed time period.
REFERENCES:
patent: 4870501 (1989-09-01), Yoshida
patent: 4876605 (1989-10-01), Ishikawa et al.
patent: 4916549 (1990-04-01), Sekizawa
patent: 5038225 (1991-08-01), Maeshima
Coles Sr. Edward L.
Lee Thomas D.
Ricoh Comany, Ltd.
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