US4236818A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Exposure time control for photographic printer
Assignee: Pako Corp
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Filing: 1979-09-07
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Granted: 1980-12-02
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Expires: 1999-09-07
Abstract
Abstract A photographic printer includes large area transmission density (LATD) sensors and a digital processor, such as a microprocessor, which calculates red, green and blue exposure times based upon the LATD sensor values. Prior to an exposure cycle, the LATD sensors are initialized, and LATD sensor readings are taken. From these initial sensor readings red, green, and blue initial exposure times are calculated, and an exposure cycle is initiated based upon these initial exposure times. During the exposure cycle, additional sensor readings continue to be taken on an asynchronous basis, and red, green, and blue exposure times are recalculated each time a reading is taken. The exposure times used during the exposure cycle are continuously modified and updated as a function of the recalculated exposure times. A running average of the sensor readings is maintained, and the modified exposure times are based upon a weighted average of the most recent sensor reading and the running average. In addition, individual bad readings are sorted out and are not included in the running average. The occurrence of greater than a predetermined number of bad readings or data points causes termination of the exposure.
Inventors
- 👤 II Jess F. Fauchier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 13:20
CPC Classifications
G; G03; G03B; G03B27/00; G03B27/72; G03B27/73; G03B27/735
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
96 words
A method of controlling red, green and blue exposure time in a photographic printer based upon red, green and blue large area transmission density (LATD) sensor readings, the method comprising: making red, green and blue LATD sensor readings prior to initiation of an exposure cycle; calculating red, green, and blue initial exposure times based upon the LATD sensor readings; initiating an exposure cycle; making LATD sensor readings during the exposure cycle; and modifying red, green and blue exposure times during the exposure cycle as a function of the LATD sensor readings made during the exposure cycle.
Claim 2
Independent Claim
96 words
A method of controlling red, green and blue exposure time in a photographic printer based upon red, green and blue large area transmission density (LATD) sensor readings, the method comprising: making red, green and blue LATD sensor readings prior to initiation of an exposure cycle; calculating red, green, and blue initial exposure times based upon the LATD sensor readings; initiating an exposure cycle; making LATD sensor readings during the exposure cycle; and modifying red, green and blue exposure times during the exposure cycle as a function of the LATD sensor readings made during the exposure cycle.
Claim 3
Dependent Claim
25 words
The method of claim 1 and further comprising: making running averages of the red, green, and blue LATD sensor readings during the exposure time cycle.
Claim 4
Dependent Claim
25 words
The method of claim 2 wherein modifying the exposure times is based upon the running averages of the red, green, and blue LATD sensor values.
Claim 5
Dependent Claim
17 words
The method of claim 3 wherein the running averages are weighted averages of the LATD sensor readings.
Claim 6
Dependent Claim
19 words
The method of claim 4 wherein the weighted average places greater weight upon the most recent LATD sensor reading.
Claim 7
Dependent Claim
24 words
The method of claim 1 and further comprising eliminating, when calculating initial or modified exposure times, LATD sensor readings falling outside a predetermined range.
Claim 8
Dependent Claim
30 words
The method of claim 6 and further comprising: terminating an exposure cycle if a predetermined number of consecutive LATD sensor readings in one color channel fall outside the predetermined range.
Claim 9
Dependent Claim
26 words
The method of claim 7 and further comprising: terminating an exposure cycle if a predetermined total number of LATD sensor readings fall outside the predetermined range.
Claim 10
Dependent Claim
39 words
The method of claim 1 wherein calculating red, green and blue initial exposure times comprises: converting the LATD sensor readings to logarithmic values; and calculating red, green and blue initial exposure times as a function of the logarithmic values.
Claim 11
Dependent Claim
42 words
The method of claim 9 wherein modifying exposure times during the exposure cycle comprises: providing logarithmic values of the LATD sensor readings; providing running averages of the logarithmic values; and recalculating exposure times based upon the running averages of the logarithmic values.
Claim 12
Dependent Claim
17 words
The method of claim 1 wherein the LATD sensor readings during the exposure cycle are made asynchronously.
Claim 13
Dependent Claim
23 words
The method of claim 11 wherein the LATD sensors provide red, green, and blue interrupt signals when each LATD sensor reading is completed.
Claim 14
Dependent Claim
64 words
The method of claim 12 wherein the blue LATD sensor is restarted after each blue interrupt signal; the green LATD sensor is started after each red interrupt signal and the red LATD sensor is left inactive; and the red LATD sensor is started after each green interrupt signal and the green LATD sensor is left inactive, until one of the exposure times is completed.
Claim 15
Independent Claim
79 words
A method of controlling red, green and blue exposure times in a photograhpic printer based upon red, green and blue large area transmission density (LATD) sensor readings, the method comprising: making a plurality of red, green and blue LATD sensor readings during an exposure cycle; calculating average red, green and blue sensor readings based upon the plurality of readings; and controlling red, green and blue exposure times as a function of the average red, green and blue sensor readings.
Claim 16
Independent Claim
79 words
A method of controlling red, green and blue exposure times in a photograhpic printer based upon red, green and blue large area transmission density (LATD) sensor readings, the method comprising: making a plurality of red, green and blue LATD sensor readings during an exposure cycle; calculating average red, green and blue sensor readings based upon the plurality of readings; and controlling red, green and blue exposure times as a function of the average red, green and blue sensor readings.
Claim 17
Dependent Claim
17 words
The method of claim 14 wherein the average red, green and blue sensor readings are weighted averages.
Claim 18
Dependent Claim
27 words
The method of claim 14 and further comprising eliminating, when calculating average red, green and blue sensor readings, any LATD sensor reading falling outside a predetermined range.
Claim 19
Dependent Claim
30 words
The method of claim 16 and further comprising: terminating an exposure cycle if a predetermined number of consecutive LATD sensor readings in one color channel fall outside the predetermined range.
Claim 20
Dependent Claim
26 words
The method of claim 17 and further comprising: terminating an exposure cycle if a predetermined total number of LATD sensor readings fall outside the predetermined range.
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) | 1983-12-02 | 1984-06-02 | 1984-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-12-02 | 1988-06-02 | 1988-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-12-02 | 1992-06-02 | 1992-12-02 | $7700.00 | Window Closed / Lapsed |