US4745488A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Image reader
Assignee: Canon Inc
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Filing: 1987-01-22
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Granted: 1988-05-17
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Expires: 2007-01-22
Abstract
Abstract An image reader, comprises a plurality of photosensors which photoelectrically convert incident light from an object to be read, a memory for storing, as correction reference data, data corresponding to photoelectric conversion outputs from said photosensors when said object to be read presents a uniform halftone image, and a correction circuit for obtaining uniform photoelectric conversion output levels among said photosensors using the correction reference data.
Inventors
- 👤 Noriyuki Kaifu
- 👤 Shinichi Seito
- 👤 Hiromi Kodama
- 👤 Katsuhiko Yamada
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 08:26
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/401
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
65 words
An image reader, comprising: a plurality of photosensors which photoelectrically convert incident light from an object to be read; memory means for storing, as correction reference data, data corresponding to photoelectric conversion outputs from said photosensors when the object to be read presents a uniform halftone image; and correction means for obtaining uniform photoelectric conversion output levels among said photosensors using the correction reference data.
Claim 2
Dependent Claim
65 words
An image reader, comprising: a plurality of photosensors which photoelectrically convert incident light from an object to be read; memory means for storing, as correction reference data, data corresponding to photoelectric conversion outputs from said photosensors when the object to be read presents a uniform halftone image; and correction means for obtaining uniform photoelectric conversion output levels among said photosensors using the correction reference data.
Claim 3
Dependent Claim
38 words
An image reader according to claim 1, wherein the correction reference data is obtained such that illuminance of light radiated on a white object to be read is decreased to be lower than that in a reading mode.
Claim 4
Dependent Claim
38 words
An image reader according to claim 1, wherein the correction reference data is obtained such that reflected incident light from a white object to be read is photoelectrically converted while a drive voltage for said photosensors is decreased.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-05-17 | 1991-11-16 | 1992-05-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-05-17 | 1995-11-16 | 1996-05-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-05-17 | 1999-11-16 | 2000-05-17 | $7700.00 | Window Closed / Lapsed |