US4985320A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Processor chemistry control strip reader and replenishment system
Assignee: Agfa Gevaert NV
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Filing: 1989-05-31
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Granted: 1991-01-15
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Expires: 2009-05-31
Abstract
Abstract A voltage set point system is employed to provide a constant illumination of a photographic test strip. The set voltage is used as the supply for a voltage divider comparator network for accurately determining exposed film density levels.
Inventors
- 👤 Charles D. Griffin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 18:23
CPC Classifications
G; G03; G03C; G03C5/00; G03C5/26; G03C5/29; G03C5/31; G03C5/02; G03D; G03D3/00; G03D3/02; G03D3/06; G03D3/065
Claims Analysis
Total Claims: 2
Claim 1
Independent Claim
200 words
A method for controlling replenishment chemistry in a photographic film processor, including a calibration circuit of the type using a light source and having one or more pre-determined density values located on a reference control strip, the location thereof being used for comparative purposes with the location of equivalent density values on a developer test control strip, the quantified difference between the measured and reference location being used to control automatically the film replenishment chemistry, wherein the improvement comprises the steps of: generating a reference voltage based on an electrical signal output from a photodetector when no control strip is present between said light source and said photodetector, said reference voltage being maintained at a substantially constant level by means of a feedback loop which regulates the intensity of light emitted by the source, and wherein upon insertion of a freshly developed test control strip between the source and the photodetector, a set voltage substantially equals the value of said reference voltage just prior to the insertion of the control strip and, wherein said set voltage is used as a set value in a voltage ratio network including at least one comparator to identify one or more pre-set density values.
Claim 2
Independent Claim
200 words
A method for controlling replenishment chemistry in a photographic film processor, including a calibration circuit of the type using a light source and having one or more pre-determined density values located on a reference control strip, the location thereof being used for comparative purposes with the location of equivalent density values on a developer test control strip, the quantified difference between the measured and reference location being used to control automatically the film replenishment chemistry, wherein the improvement comprises the steps of: generating a reference voltage based on an electrical signal output from a photodetector when no control strip is present between said light source and said photodetector, said reference voltage being maintained at a substantially constant level by means of a feedback loop which regulates the intensity of light emitted by the source, and wherein upon insertion of a freshly developed test control strip between the source and the photodetector, a set voltage substantially equals the value of said reference voltage just prior to the insertion of the control strip and, wherein said set voltage is used as a set value in a voltage ratio network including at least one comparator to identify one or more pre-set density values.
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) | 1994-01-14 | 1994-07-16 | 1995-01-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-01-14 | 1998-07-16 | 1999-01-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-01-14 | 2002-07-16 | 2003-01-15 | $7700.00 | Window Closed / Lapsed |