US3895876A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Quantized indication apparatus
Assignee: Pentax Corp
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Filing: 1973-09-10
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Granted: 1975-07-22
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Expires: 1993-09-10
Abstract
Abstract Apparatus provides a quantized indication of a variable parameter that varies in relation to a variable signal advantageously provided by a photosensitive device in a camera. Preferably, exposure time is the indicated parameter, exposure time being of course a function of object brightness. The apparatus comprises a logarithmic compression circuit, a plurality of logarithmic expansion circuits each responsive to the logarithmic compression circuit, and indicating means including a plurality of switching elements each having a different threshold of switching. Preferably, the switching elements control lamps that are selectively lit to indicate which of a plurality of ranges encompasses the exposure time.
Inventors
- 👤 Chiharu Mori
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 06:47
CPC Classifications
G; G03; G03B; G03B7/00; G03B7/08; G03B7/081; G03B7/083; G01; G01J; G01J1/00; G01J1/42; G01J1/44; G03B17/00; G03B17/18; G03B17/20; G03B7/003; G03B9/00; G03B9/70
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
145 words
Apparatus for providing a quantized indication of a parameter that varies in relation to a variable input signal which comprises: a logarithmic compression circuit including a controllable voltage source providing a first voltage and control means responsive to the signal for controlling the controllable voltage source so that the first voltage varies in logarithmic relationship with respect to variations in the signal; a plurality of logarithmic expansion circuits each including a voltage-controlled current source controlled by the first voltage and each having an inverse-logarithmic voltage-in to current-out transfer characteristic; and indicating means including a plurality of threshold-detecting switching elements respectively corresponding to the plurality of expansion circuits, each switching element having a different threshold and being operative to switch between opposite switching conditions in accordance with whether the current out of its corresponding expansion circuit is on one side or the other of its threshold.
Claim 2
Dependent Claim
145 words
Apparatus for providing a quantized indication of a parameter that varies in relation to a variable input signal which comprises: a logarithmic compression circuit including a controllable voltage source providing a first voltage and control means responsive to the signal for controlling the controllable voltage source so that the first voltage varies in logarithmic relationship with respect to variations in the signal; a plurality of logarithmic expansion circuits each including a voltage-controlled current source controlled by the first voltage and each having an inverse-logarithmic voltage-in to current-out transfer characteristic; and indicating means including a plurality of threshold-detecting switching elements respectively corresponding to the plurality of expansion circuits, each switching element having a different threshold and being operative to switch between opposite switching conditions in accordance with whether the current out of its corresponding expansion circuit is on one side or the other of its threshold.
Claim 3
Dependent Claim
44 words
Apparatus according to claim 1 wherein the logarithmic compression circuit includes a photosensitive element and the control means includes means for controlling the controllable voltage source so that the first voltage has a value proportional to a selected one of the APEX-represented photographic parameters.
Claim 4
Dependent Claim
23 words
Apparatus according to claim 2 wherein each voltage-controlled source comprises a bipolar transistor having its base-emitter junction connected to receive the first voltage.
Claim 5
Dependent Claim
41 words
Apparatus according to claim 3 wherein the threshold detecting switching elements Each include a transistor having a resistor connected in parallel with its base-emitter junction, the current from the corresponding current source being provided to develop a voltage across the resistor.
Claim 6
Dependent Claim
79 words
A quantized indication arrangement for a camera, which comprises: a voltage source providing a voltage whose value is determined in proportion to APEX-represented values of photographic parameters, a controllable current source having said voltage value as its input and having a non-linear input-voltage to output-current transfer characteristic; and comparing means for controlling the quantized indication, the comparing means including switching means operative to switch in accordance with the value of the output current relative to a predetermined threshold value.
Claim 7
Dependent Claim
79 words
A quantized indication arrangement for a camera, which comprises: a voltage source providing a voltage whose value is determined in proportion to APEX-represented values of photographic parameters, a controllable current source having said voltage value as its input and having a non-linear input-voltage to output-current transfer characteristic; and comparing means for controlling the quantized indication, the comparing means including switching means operative to switch in accordance with the value of the output current relative to a predetermined threshold value.
Claim 8
Dependent Claim
16 words
An arrangement according to claim 5 wherein the controllable current source comprises a bipolar type transistor.
Claim 9
Dependent Claim
31 words
An arrangement according to claim 6, wherein said voltage value is applied to the base-emitter junction of the transistor, the transistor having a logarithmically expanded current relative to said voltage value.
Claim 10
Dependent Claim
42 words
An arrangement according to claim 5 wherein the comparing means includes a resistor across which there is developed a voltage proportional to the output current, and the switching means comprises a transistor having its base-emitter junction connected in parallel with the resistor.
Claim 11
Dependent Claim
19 words
An arrangement according to claim 8 wherein the resistor has a resistance value established in proportion to exposure time.
Claim 12
Dependent Claim
32 words
An arrangement according to claim 5 further comprising a plurality of additional ones of said controllable current source, each comprising a transistor having its base-emitter junction connected to receive the voltage value.
References Cited (Backward Citations)
US3723014A
Cited
US3737240A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-07-21 | 1979-01-20 | 1979-07-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-21 | 1983-01-20 | 1983-07-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-21 | 1987-01-20 | 1987-07-22 | $7700.00 | Window Closed / Lapsed |