US4010479A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Focusing apparatus for optical systems
Assignee: Pentax Corp
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Filing: 1975-06-30
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Granted: 1977-03-01
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Expires: 1995-06-30
Abstract
Abstract Focusing apparatus for use in optical systems, such as photographing cameras, is disclosed. The focusing apparatus of the invention comprises an electronic system for developing, through either a single or two separate channels, pulse trains, the number of pulses contained in the pulse trains being related to the brightness of the image forming light received by the optical system as focused on photoconductive elements. The electronic system further includes a comparing subsystem for comparing the number of pulses included in the two pulse trains and, in accordance therewith, generating an information output signal related to the focus state of the optical system. Alternatively, the output signal may control a drive system adapted to move the imaging lens portion of the optical system toward focus.
Inventors
- 👤 Tsukumo Nobusawa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 20:40
CPC Classifications
G; G02; G02B; G02B7/00; G02B7/28; G02B7/36
Claims Analysis
Total Claims: 27
Claim 1
Independent Claim
202 words
Focusing apparatus for use in an optical system comprising: at least one photoconductive elememt mounted such that an imaging lens forming part of an optical system directs light onto its photosensitive surface and having an internal resistance that varies in accordance with the intensity of light impinging onto its photo sensitive surface; pulse generating means for generating pulse trains, said pulse generating means connected to said at least one photoconductive element such that the frequency of the pulses generated by said pulse generating means is related to the internal resistance of said at least one photoconductive element; counting means connected to said pulse generating means for counting two pulse trains generated by said pulse generating means during a predetermined time period; comparing means connected to said counting means for comparing said two pulse trains counted by said counting means; and, output means connected to said comparing means for providing one form of output when said comparing means determines that said two pulse trains include an equal number of pulses and a different form of output when said comparing means determines that said two pulse trains include different numbers of pulses, said equality of pulses occurring when said optical system is in focus.
Claim 2
Dependent Claim
202 words
Focusing apparatus for use in an optical system comprising: at least one photoconductive elememt mounted such that an imaging lens forming part of an optical system directs light onto its photosensitive surface and having an internal resistance that varies in accordance with the intensity of light impinging onto its photo sensitive surface; pulse generating means for generating pulse trains, said pulse generating means connected to said at least one photoconductive element such that the frequency of the pulses generated by said pulse generating means is related to the internal resistance of said at least one photoconductive element; counting means connected to said pulse generating means for counting two pulse trains generated by said pulse generating means during a predetermined time period; comparing means connected to said counting means for comparing said two pulse trains counted by said counting means; and, output means connected to said comparing means for providing one form of output when said comparing means determines that said two pulse trains include an equal number of pulses and a different form of output when said comparing means determines that said two pulse trains include different numbers of pulses, said equality of pulses occurring when said optical system is in focus.
Claim 3
Dependent Claim
14 words
The focusing apparatus claimed in claim 1 wherein said output means includes a display.
Claim 4
Dependent Claim
152 words
The focusing apparatus claimed in claim 1 wherein: said at least one photoconductive element includes two photoconductive elements, each photoconductive element having an internal resistance that varies in accordance with the intensity of light impinging on its photo sensitive, said photoconductive elements being mounted in symmetrical positions about the optical axis of said optical system; said pulse generator means includes first and second oscillators connected to said first and second photoconductive elements, respectively, such that said first and second photoconductive elements control the frequency of pulses generated by said first and second oscillators, respectively; and, said counting means includes first and second counters, one connected to each of said first and second oscillators so as to count pulses generated by said first and second oscillators, said first and second counters being connected to said comparing means such that said comparing means compares the pulse counts counted by said first and second counters.
Claim 5
Dependent Claim
30 words
The focusing apparatus claimed in claim 3 including a control system for controlling the application of pulses generated by said first and second oscillators to said first and second counters.
Claim 6
Dependent Claim
103 words
The focusing apparatus claimed in claim 4 wherein said control means comprises: a timer; a first control AND gate having one input connected to the output of said timer and a second input connected to the output of said first oscillator, the output of said first control AND gate being connected to the input of said first counter; and, a second control AND gate having one input connected to the output of said timer and a second input connected to the output of said second oscillator, the output of said second control AND gate being connected to the input of said second counter.
Claim 7
Dependent Claim
54 words
The focusing apparatus claimed in claim 5 wherein said first and second counters are multi-stage counters formed such that they have related stages and wherein said comparing means includes a plurality of compare AND gates at least one of which is connected to corresponding outputs of related stages of said first and second counters.
Claim 8
Dependent Claim
29 words
The focusing apparatus claimed in claim 6 wherein said control means includes an output AND gate having inputs connected to the outputs of said plurality of compare AND gates.
Claim 9
Dependent Claim
29 words
The focusing apparatus claimed in claim 7 wherein said control means also includes a starting circuit connected to said timer and to one input of said output AND gate.
Claim 10
Dependent Claim
24 words
The focusing apparatus claimed in claim 8 wherein said output means also includes a display connected to the output of said output AND gate.
Claim 11
Dependent Claim
15 words
The focusing apparatus as claimed in claim 9 wherein said timer is a monostable multivibrator.
Claim 12
Dependent Claim
123 words
The focusing apparatus as claimed in claim 1 wherein said counting means includes: a first counter connected to the output of said pulse generating means for counting the pulses generated by said pulse generating means during sequential predetermined time periods; a second counter connected to the output of said pulse generating means for counting the pulses generated by said pulse generator means over said sequential predetermined time periods simultaneously with the counting of said same pulses by said first counter; a third counter; and, a transfer circuit for transferring the pulse count counted by said second counter after the end of one of said sequential predetermined time periods to said third counter, said first and third counters being connected to said comparing means.
Claim 13
Dependent Claim
36 words
The focusing apparatus as claimed in claim 11 including a first oscillator for generating additional pulses and applying said additional pulses to said first and third counters subsequent to each of said sequential predetermined time periods.
Claim 14
Dependent Claim
82 words
The focusing apparatus claimed in claim 12 including a sequential control means connected to said pulse generator means, said first oscillator and said transfer circuit for controlling the operation of said pulse generator, said oscillator and said transfer circuit in a sequential manner such that subsequent to each of said sequential predetermined time periods, said first oscillator applies pulses to said first and third counters prior to said transfer circuit transferring a pulse count from said second counter to said third counter.
Claim 15
Dependent Claim
26 words
The focusing apparatus claimed in claim 13 wherein the output of said comparing means is connected to the reset inputs of said first and third counters.
Claim 16
Dependent Claim
95 words
The focusing apparatus claimed in claim 14 wherein said control means includes: a selector for generating four sequential control outputs, one of said control outputs being connected to said pulse generating means and a second of said control outputs being connected to said first oscillator; a second oscillator connected to receive the third of said control outputs and connected to said transfer circuit for applying an enabling pulse to said transfer circuit; and, a third oscillator connected to receive the fourth of said control outputs and connected to the reset input of said second counter.
Claim 17
Dependent Claim
14 words
The focusing apparatus claimed in claim 15 wherein said output means includes a display.
Claim 18
Dependent Claim
37 words
The focusing apparatus claimed in claim 15 wherein said output means includes a drive mechanism connected to move said imaging lens adapted to image light onto the photo sensitive surface of said at least one photoconductive element.
Claim 19
Dependent Claim
111 words
The focusing apparatus claimed in claim 1 wherein said counting means comprises: a first counter connected to receive the pulse output of said pulse generating means during said predetermined time period; a second counter connected to receive the pulse output of said pulse generator means simultaneously with the receipt of pulses by said first counter during said predetermined time period; a first shift register; a first transfer circuit for transferring the output of said first counter to said first shift register; a second shift register; a second transfer circuit for transferring the output of said second counter to said second shift register, said shift registers being connected to said comparing means.
Claim 20
Dependent Claim
32 words
The focusing apparatus claimed in claim 18 including a shifting means connected to said shift registers for shifting the counts stored in said shift registers through said first and second shift registers.
Claim 21
Dependent Claim
95 words
The focusing appartus claimed in claim 19 including a control means for controlling the operation of said pulse generating means, said first and second transfer circuits and said shifting means such that subsequent to said pulse generating means generating pulses over said predetermined time period, the output of said first counter is transferred by said first transfer circuit to said shift register: the counts contained in said first and second shift registers are shifted therethrough, and, then, the output of said second counter is transferred by said second transfer circuit to said second shit register.
Claim 22
Dependent Claim
62 words
The focusing apparatus claimed in claim 20 wherein said comparing means is connected to the reset inputs of said first counter and said first and second shift registers so as to reset said first counter and said first and second shift registers prior to the output of said second counter being transferred by said second transfer circuit to said second shift register.
Claim 23
Dependent Claim
133 words
The focusing apparatus claimed in claim 21 wherein said control means includes: a selector adapted to generate five control outputs in sequence, the first control being applied to said pulse generating means for controlling the operation of said pulse generating means such that it generates pulses over said predetermined time period; a first oscillator having its input connected to receive the second control of said selector and its output connected to said first transfer circuit; a second oscillator having its intput connected to receive the third control output of said selector and its output connected to the shift inputs of said first and the second shift registers; a third oscillator having its input connected to receive the fourth control output of said selector and its output connected to said second transfer circuit; and,
Claim 24
Dependent Claim
28 words
a fourth oscillator having its intput connected to receive the fifth control output of said selector and its output connected to the reset input of said second counter.
Claim 25
Dependent Claim
28 words
a fourth oscillator having its intput connected to receive the fifth control output of said selector and its output connected to the reset input of said second counter.
Claim 26
Dependent Claim
14 words
The focusing apparatus claimed in claim 22 wherein said output means includes a display.
Claim 27
Dependent Claim
37 words
The focusing apparatus claimed in claim 22 wherein said output means includes a drive mechanism connected to move said imaging lens adapted to image light onto the photo sensitive surface of said at least one photoconductive element.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-02-29 | 1980-08-30 | 1981-03-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-02-29 | 1984-08-30 | 1985-03-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-02-29 | 1988-08-30 | 1989-03-01 | $7700.00 | Window Closed / Lapsed |