US3810203A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electrical controls for camera shutters
Assignee: Individual
•
Filing: 1972-11-24
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Granted: 1974-05-07
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Expires: 1992-11-24
Abstract
Abstract An electrical system for controlling the operation of a camera shutter. The system includes a shutter-operating circuit section controlled directly from a logarithmic expansion circuit section. A logarithmic compression circuit section is provided for receiving light from the object which is to be photographed and for providing a given output. An emitter-follower circuit section is electrically connected between the logarithmic-compression circuit section and the logarithmic-expansion circuit section to receive the output from the former and to perform certain computations determining the input to the latter. A variable resistor means is operatively connected as a load resistance to the emitter-follower circuit section in order introduce into the computations exposure-determing factors in addition to the light at the object. This variable resistor means has a resistance value which changes in accordance with an index function according to the additive APEX system in relation to given conditions such as the diaphragm setting or film speed.
Inventors
- 👤 C Mori
- 👤 K Ota
- 👤 H Togawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 20:49
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/083
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
164 words
In an electrical system for controlling a camera shutter, shutter-operating circuit means, logarithmic-expansion circuit means electrically connecting with said shutter-operating circuit means for controlling the operation thereof, photosensitive means for receiving light from the object to be photographed, logarithmic-compression circuit means electrically connected with said photosensitive means for logarithmically compressing signals from said photosensitive means, emitter-follower computation circuit means electrically connected between said logarithmiccompression circuit means and said logarithmic-expansion circuit means for performing computations on the output received from said logarithmic-compression circuit means and for forming an input to said logarithmic-expansion circuit means, and variable resistor conversion means coupled into an emitter circuit of said emitter-follower computation circuit means for introducing at least one additional exposure determining factor such as the setting of the diaphragm or the film speed and converting said factor into an exponential function whereby said computations performed by said emitter-follower circuit means includes the algebraic addition of the output from the logarithmic-compression circuit means and the additional exposure determining factor.
Claim 2
Dependent Claim
164 words
In an electrical system for controlling a camera shutter, shutter-operating circuit means, logarithmic-expansion circuit means electrically connecting with said shutter-operating circuit means for controlling the operation thereof, photosensitive means for receiving light from the object to be photographed, logarithmic-compression circuit means electrically connected with said photosensitive means for logarithmically compressing signals from said photosensitive means, emitter-follower computation circuit means electrically connected between said logarithmiccompression circuit means and said logarithmic-expansion circuit means for performing computations on the output received from said logarithmic-compression circuit means and for forming an input to said logarithmic-expansion circuit means, and variable resistor conversion means coupled into an emitter circuit of said emitter-follower computation circuit means for introducing at least one additional exposure determining factor such as the setting of the diaphragm or the film speed and converting said factor into an exponential function whereby said computations performed by said emitter-follower circuit means includes the algebraic addition of the output from the logarithmic-compression circuit means and the additional exposure determining factor.
Claim 3
Dependent Claim
44 words
The combination of claim 1 and wherein said emitter-follower computation circuit means includes a single transistor and wherein said variable resistor conversion means includes a single variable resistor for introducing into the emitter circuit both the setting of the diaphragm and the film speed.
Claim 4
Dependent Claim
56 words
The combination of claim 1 and wherein said emitter-follower computation circuit means includes a pair of transistors connected in cascade one after the other and wherein said variable resistor conversion means includes a pair of variable resistors respectively connected in each of the emitter circuits for respectively introducing the factors of diaphragm setting and film speed.
Claim 5
Dependent Claim
34 words
The combination of claim 1 and wherein said variable resistor conversion means has a number of predetermined settings and provides at any two successive settings resistance values one of which is double the other.
Claim 6
Dependent Claim
65 words
The combination of claim 1 and wherein said logarithmic-compression circuit means includes logArithmic-compression components having given temperature characteristics and said logarithmic-expansion circuit means and said emitter-follower computation circuit means including transistors having given temperature characteristics, and the latter three circuit means being electrically connected to each other for providing a relationship according to which the latter temperature characteristics cancel those of the former temperature characteristics.
Claim 7
Dependent Claim
27 words
The combination of claim 1 and wherein an emitter-follower buffer circuit means is electrically connected between said logarithmic compression circuit means and said emitter-follower computation circuit means.
Claim 8
Dependent Claim
27 words
The combination of claim 1 and wherein said emitter-follower computation circuit means is directly connected between said logarithmic compression circuit means and said logarithmic expansion circuit means.
Claim 9
Dependent Claim
156 words
An electrical syytem for controlling a camera shutter including, photosensitive means for generating an electric current which is in proportion to intensity of light received from an object to be photographed, logarithmic-compression means comprising at least one logarithmic-compression element serially connected to said photosensitive means, logarithmic-expansion means for converting a linearly variable voltage into an electric current which varies in the form of an exponential function, timing circuit means for setting the shutter time in inverse proportion to said last-mentioned electric current, emitter-follower circuit means electrically connected between said logarithmic-compression means and said logarithmic-expansion means for performing computations for coordination therebetween, and variable resistance means coupled as a load resistance of said emitter-follower circuit means for converting a selected aperture value and a selected film speed value into an exponential function, whereby said emitter-follower circuit means provides said linearly variable voltage by combining the logarithmic compression values and the exponential function from the variable resistance means.
Claim 10
Dependent Claim
156 words
An electrical syytem for controlling a camera shutter including, photosensitive means for generating an electric current which is in proportion to intensity of light received from an object to be photographed, logarithmic-compression means comprising at least one logarithmic-compression element serially connected to said photosensitive means, logarithmic-expansion means for converting a linearly variable voltage into an electric current which varies in the form of an exponential function, timing circuit means for setting the shutter time in inverse proportion to said last-mentioned electric current, emitter-follower circuit means electrically connected between said logarithmic-compression means and said logarithmic-expansion means for performing computations for coordination therebetween, and variable resistance means coupled as a load resistance of said emitter-follower circuit means for converting a selected aperture value and a selected film speed value into an exponential function, whereby said emitter-follower circuit means provides said linearly variable voltage by combining the logarithmic compression values and the exponential function from the variable resistance means.
References Cited (Backward Citations)
US3533348A
Cited
US3535530A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-05-06 | 1977-11-05 | 1978-05-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-06 | 1981-11-05 | 1982-05-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-06 | 1985-11-05 | 1986-05-07 | $7700.00 | Window Closed / Lapsed |