US4093375A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Methods and apparatus for automatic exposure control
Assignee: Hoechst AG
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Filing: 1976-04-26
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Granted: 1978-06-06
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Expires: 1996-04-26
Abstract
Abstract This invention relates to a method of exposure control in photographic printing apparatus for printing from originals made on different types of photographic material, the method comprising: Determining which of at least two types (such as silver halide or diazo film) of photographic material the original employs by an examination of the spectral transmission characteristics of the original, Determining the image density of the original, and Controlling the exposure in accordance with both the type of material as determined and the image density.
Inventors
- 👤 Dorothee Griesch
- 👤 Herbert Schroter
- 👤 Peter Schwagler
- 👤 Eckehard Stein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 20:09
CPC Classifications
G; G03; G03B; G03B27/00; G03B27/72; G03B27/80; G03G; G03G15/00; G03G15/04; G03G15/043
Claims Analysis
Total Claims: 33
Claim 1
Independent Claim
79 words
A method of exposure control in photographic printing apparatus for printing from originals made on different types of photographic material, the method comprising: determining which of at least two types (such as silver halide or diazo film) of photographic material the original employs by an examination of the spectral transmission characteristics of the original, determining the image density of the original, and controlling the exposure in accordance with both the type of material as determined and the image density.
Claim 2
Independent Claim
79 words
A method of exposure control in photographic printing apparatus for printing from originals made on different types of photographic material, the method comprising: determining which of at least two types (such as silver halide or diazo film) of photographic material the original employs by an examination of the spectral transmission characteristics of the original, determining the image density of the original, and controlling the exposure in accordance with both the type of material as determined and the image density.
Claim 3
Dependent Claim
27 words
A method as claimed in claim 1 wherein the photographic material is microfilm and the image density is determined from the actinic light transmission through the microfilm.
Claim 4
Dependent Claim
31 words
A method as claimed in claim 1, wherein the spectral transmission characteristics in a band in the red and infrared regions are examined to distinguish silver halide material from diazo material.
Claim 5
Dependent Claim
23 words
A method as claimed in claim 3, wherein the band in the red and infrared regions commences at approximately 650 nanometers wave length.
Claim 6
Dependent Claim
20 words
A method as claimed in claim 1, wherein the spectral transmission characteristics in at least two spectral bands are compared.
Claim 7
Dependent Claim
38 words
A method as claimed in claim 5, wherein the comparison of the characteristics in at least two spectral bands includes subtracting a signal representing the transmission in one band from a signal representing the transmission in another band.
Claim 8
Dependent Claim
38 words
A method as claimed in claim 5, wherein the comparison of the characteristics in at least two spectral bands includes dividing a signal representing the transmission in one band by a signal representing the transmission in another band.
Claim 9
Dependent Claim
29 words
A method as claimed in claim 1, wherein the spectral transmission characteristics in at least two bands in the actinic region are examined to distinguish between different diazo materials.
Claim 10
Dependent Claim
23 words
A method as claimed in claim 8, wherein one of the said bands extends from approximately 450 to approximately 500 nanometers wave length.
Claim 11
Dependent Claim
23 words
A method as claimed in claim 8, wherein one of the said bands extends from approximately 550 to approximately 600 nanometers wave length.
Claim 12
Dependent Claim
79 words
Photographic printing apparatus for printing from originals made on different types of photographic material, the apparatus comprising: means to determine which of at least two types (such as silver halide or diazo film) of photographic material the original employs comprising means to examine the spectral transmission characteristics of said original, means to determine the image density of the original, and means to control the exposure in accordance with both the type of material as determined and the image density.
Claim 13
Dependent Claim
79 words
Photographic printing apparatus for printing from originals made on different types of photographic material, the apparatus comprising: means to determine which of at least two types (such as silver halide or diazo film) of photographic material the original employs comprising means to examine the spectral transmission characteristics of said original, means to determine the image density of the original, and means to control the exposure in accordance with both the type of material as determined and the image density.
Claim 14
Dependent Claim
32 words
Apparatus as claimed in claim 11, wherein the apparatus is a microfilm re-enlargement apparatus and the means to determine the image density comprises means to measure actinic light transmission through the microfilm.
Claim 15
Dependent Claim
35 words
Apparatus as claimed in claim 11, wherein the means to examine the spectral transmission characteristics is arranged to respond to transmission in the red and infrared regions to distinguish silver halide material from diazo material.
Claim 16
Dependent Claim
34 words
Apparatus as claimed in claim 13, wherein the means to examine the spectral transmission characteristics comprises a photo-electric transducer and a filter operative to respond to wave lengths in the red and infrared regions.
Claim 17
Dependent Claim
22 words
Apparatus as claimed in claim 14, wherein the photo-electric transducer and filter are responsive to wave lengths commencing at approximately 650 nanometers.
Claim 18
Dependent Claim
28 words
Apparatus as claimed in claim 11, wherein the means to examine the spectral transmission characteristics is arranged to compare the transmission characteristics in at least two spectral bands.
Claim 19
Dependent Claim
41 words
Apparatus as claimed in claim 16, wherein the means to examine the spectral transmission characteristics comprises a first photo-electric transducer and filter to measure transmission in one band and a second photo-electric transducer and filter to measure transmission in another band.
Claim 20
Dependent Claim
30 words
Apparatus as claimed in claim 17, wherein a difference-forming circuit is connected to the outputs of the first and second transducers to compare the said transmissions by forming their difference.
Claim 21
Dependent Claim
30 words
Apparatus as claimed in claim 17, wherein a quotient-forming circuit is connected to the outputs of the first and second transducers to compare the said transmissions by forming their quotient.
Claim 22
Dependent Claim
27 words
Apparatus as claimed in claim 17, wherein the first transducer and filter are responsive to a band extending from approximately 450 to approximately 500 nanometers wave length.
Claim 23
Dependent Claim
27 words
Apparatus as claimed in claim 19, wherein the second transducer and filter are responsive to a band extending from approximately 550 to approximately 600 nanometers wave length.
Claim 24
Dependent Claim
74 words
Apparatus as claimed in claim 12, wherein the means to determine the image density comprises a first photo-electric transducer and filter responsive to actinic light and the means to examine the spectral transmission characteristics comprises a second photo-electric transducer arranged to respond to wave lengths in the red and infrared regions and a difference-forming circuit connected to the outputs of the first and second transducers to compare the said transmissions by forming their difference.
Claim 25
Dependent Claim
27 words
Apparatus as claimed in claim 22, wherein a dichroic plate is provided to transmit light to the first transducer and to reflect light to the second transducer.
Claim 26
Dependent Claim
63 words
Apparatus as claimed in claim 11, wherein the means to control the exposure comprises a respective exposure function generator for each type of material determinable by the means to determine the type of photographic material, and means to connect one of the exposure function generators to the output of the means to determine the image density in accordance with the material type determined.
Claim 27
Dependent Claim
66 words
Apparatus as claimed in claim 11, wherein the means to control the exposure comprises an exposure time/function generator having a common characteristic for all types of material determinable by the means to determine the type of photographic material and arranged to respond to the output of the means to determine the image density, and means to control light intensity in accordance with the material type determined.
Claim 28
Dependent Claim
31 words
Apparatus as claimed in claim 14, wherein the means to determine the type of photographic material includes a comparator operative to compare the output of the transducer with a predetermined level.
Claim 29
Dependent Claim
34 words
Apparatus as claimed in claim 18, wherein the means to determine the type of photographic material includes a comparator operative to compare the output of the difference-forming circuit with one or more predetermined levels.
Claim 30
Dependent Claim
34 words
Apparatus as claimed in claim 19, wherein the means to determine the type of photographic material includes a comparator operative to compare the output of the quotient-forming circuit with one or more predetermined levels.
Claim 31
Dependent Claim
32 words
Apparatus as claimed in claim 22, wherein the means to determine the type of photographic material includes a comparator operative to compare the output of the difference-forming circuit with a predetermined level.
Claim 32
Dependent Claim
28 words
Apparatus as claimed in claim 24, wherein each exposure function generator is operative to provide a respective exposure time for each value in a range of image densities.
Claim 33
Dependent Claim
48 words
Apparatus as claimed in claim 26 wherein the comparator is connected to a switching circuit operative to select one of a plurality of function generators, each function generator being adapted to control the exposure in accordance with both the type of material as determined and the image density.
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) | 1981-06-05 | 1981-12-05 | 1982-06-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-06-05 | 1985-12-05 | 1986-06-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-06-05 | 1989-12-05 | 1990-06-06 | $7700.00 | Window Closed / Lapsed |