Patent US4906842A successfully refreshed from Google Patents.
US4906842A
Expired / Lapsed
US
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Document counter and endorser with light source control
Assignee: De la Rue Systems Americas Corp
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Filing: 1989-04-07
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Granted: 1990-03-06
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Expires: 2009-04-07
Abstract
Abstract Apparatus for examining documents moved along a path between a light source normally energized at a first level and a photodetector, in which a first potential proportional to the long term average value of the photodetector output with no document between the light source and the photodetector and a second potential proportional to the instantaneous value of the photodetector output are compared to energize the light source at a higher level by shorting part of the resistance in the normal energizing circuit when the second potential falls below a predetermined percentage of the first potential.
Inventors
- 👤 Richard A. Melcher
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:17
CPC Classifications
G; G06; G06K; G06K13/00; G06K13/02; G06K13/06; G06K13/067
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
135 words
Apparatus for examining documents including in combination, a light source, a photodetector, means mounting said photodetector and said light source in spaced relationship with light from said source directed toward said photoconductor, means for moving documents along a path between said light source and said photodetector, means normally energizing said source at a first level, means responsive to said photodetector for storing a first potential proportional to the long term average value of the photodetector output when no document is present, means for comparing said first potential with a second potential proportional to the instantaneous value of said photodetector output for producing a control signal when said second potential is less than said first potential, and means responsive to said control signal for energizing said source at a second level higher than said first level.
Claim 2
Dependent Claim
135 words
Apparatus for examining documents including in combination, a light source, a photodetector, means mounting said photodetector and said light source in spaced relationship with light from said source directed toward said photoconductor, means for moving documents along a path between said light source and said photodetector, means normally energizing said source at a first level, means responsive to said photodetector for storing a first potential proportional to the long term average value of the photodetector output when no document is present, means for comparing said first potential with a second potential proportional to the instantaneous value of said photodetector output for producing a control signal when said second potential is less than said first potential, and means responsive to said control signal for energizing said source at a second level higher than said first level.
Claim 3
Dependent Claim
51 words
Apparatus as in claim 1 in which said means normally energizing said light source at said first level includes a potential source and a resistance connected in series with said light source and in which said means responsive to said control signal comprises means for shorting a portion of said resistance.
Claim 4
Dependent Claim
61 words
Apparatus as in claim 1 in which said potential storing means comprises a capacitor, means responsive to said first potential for charging said capacitor through a short time constant path when said first potential exceeds said second potential and means providing a relatively longer time constant path for discharging said capacitor when said first potential is less than said second potential.
Claim 5
Dependent Claim
106 words
Apparatus as in claim 1 in which said means normally energizing said source at said first level includes a potential source and a resistance connected in series with said light source, in which said means responsive to said control signal comprises means for shorting a portion of said resistance, and in which said potential storing means comprises a capacitor, means responsive to said first potential for charging said capacitor through a short time constant path when said first potential exceeds said second potential and means providing a relatively longer time constant path for discharging said capacitor when said first potential is less than said second potential.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-03-05 | 1993-09-04 | 1994-03-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-03-05 | 1997-09-04 | 1998-03-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-03-05 | 2001-09-04 | 2002-03-06 | $7700.00 | Window Closed / Lapsed |