US4906842A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Document counter and endorser with light source control
Assignee: De la Rue Systems Americas Corp
•
Filing: 1989-04-07
•
Granted: 1990-03-06
•
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 17:03
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.
References Cited (Backward Citations)
US3944979A
Cited
US4225808A
Cited
US4406530A
Cited
US4808809A
Cited
US4745272A
Cited
US4727290A
Cited
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 |