US3751154A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic rangefinder electronic circuitry
Assignee: Eastman Kodak Co
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Filing: 1970-07-13
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Granted: 1973-08-07
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Expires: 1990-07-13
Abstract
Abstract This invention relates to automatic range finder circuitry for cooperative utilization with apparatus, such as a photographic camera or the like, using triangulation for range distance measurement, and having an automatic range finder mechanism. The apparatus is arranged to sweep a collimated light beam across a plane which includes a subject of interest, and the reflected light returning to the apparatus is imaged on spaced photoelectric transducers differentially connected to produce a varying electrical signal. The range finder mechanism includes a cam adapted to move as a function of the sweeping light beam. When the reflected light falls equally on the photoelectric transducers the range distance has been established. The present invention supports this apparatus by providing circuitry for detecting the instant that the reflected illumination on the photoelectric transducers is equal, and for providing an output signal which is used to lock the cam against further displacement. The range distance intelligence, defined by the locked cam position, can then be utilized for any convenient purpose.
Inventors
- 👤 J Frazee
- 👤 H Murphy
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 12:13
CPC Classifications
G; G02; G02B; G02B7/00; G02B7/28; G02B7/30; G02B7/32
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
220 words
In a triangulation rangefinding apparatus for receiving light modulated at a selected frequency and reflected from a subject spaced from the apparatus whose distance from the apparatus is to be determined and including first and second, spaced photosensitive means for respectively varying intensities of the reflected light, the distance between the apparatus and the subject being determined when the reflected light received on both said photosensitive means is substantially equal, the combination comprising: a. a difference amplifier connected to said first and second photosensitive means for providing a first difference signal; b. a push-pull amplifier responsive to said first difference signal for providing push-pull output signals; c. reference signal means for providing two synchronous pulse signals 180* out of phase and at the selected frequency at which the light is modulated; d. detector means responsive to said push-pull output signals and said two synchronous pulse signals for providing a second signal, said second signal having a waveform characterized by a relatively positive half cycle when the first photosensitive means receives more reflected light than the second photosensitive means and a relatively negative half cycle when the second photosensitive means receives more reflected light than the first photosensitive means; and e. crossover means responsive to said second signal for detecting when said waveform changes from one half cycle to the other.
Claim 2
Dependent Claim
220 words
In a triangulation rangefinding apparatus for receiving light modulated at a selected frequency and reflected from a subject spaced from the apparatus whose distance from the apparatus is to be determined and including first and second, spaced photosensitive means for respectively varying intensities of the reflected light, the distance between the apparatus and the subject being determined when the reflected light received on both said photosensitive means is substantially equal, the combination comprising: a. a difference amplifier connected to said first and second photosensitive means for providing a first difference signal; b. a push-pull amplifier responsive to said first difference signal for providing push-pull output signals; c. reference signal means for providing two synchronous pulse signals 180* out of phase and at the selected frequency at which the light is modulated; d. detector means responsive to said push-pull output signals and said two synchronous pulse signals for providing a second signal, said second signal having a waveform characterized by a relatively positive half cycle when the first photosensitive means receives more reflected light than the second photosensitive means and a relatively negative half cycle when the second photosensitive means receives more reflected light than the first photosensitive means; and e. crossover means responsive to said second signal for detecting when said waveform changes from one half cycle to the other.
Claim 3
Dependent Claim
26 words
The invention as set forth in claim 1 wherein the first photosensitive means includes a first photodiode and the second photosensitive means includes a second photodiode.
Claim 4
Dependent Claim
72 words
The invention as set forth in claim 1 wherein said reference signal means comprises a phototransistor and dual cooperating transistors, said phototransistor being exposed to light amplitude modulated at the same selected frequency as said reflected amplitude modulated light, the photocurrents produced by said phototransistor being coupled to said dual cooperating transistors to produce alternate ON or OFF operation for each of said cooperating transistors to provide said two synchronous pulse signals.
Claim 5
Dependent Claim
58 words
The invention as set forth in claim 1 wherein said detector means comprises two field effect transistors each having a source, a gate, and a drain, the respective sources being connected to receive said push-pull outputs, the respective gates being connected to receive said synchronous pulse signals, the drains being connected in common to provide said second signal.
Claim 6
Dependent Claim
115 words
The invention as set forth in claim 1 wherein said crossover means comprises a first transistor, a second transistor, zener diode means, and a controlled rectifier means having a gate electrode, said first transistor means being connected in the common emitter configuration having its base responsive to the voltage excursions of said second signal, said second transistor being connected as an emitter follower having its base connected to the collector of said first transistor and its emitter connected to said zener diode means, said zener diode means being connected to said gate electrode, whereby when said waveform crosses from one half cycle to the other, said output control signal is applied to said gate electrode.
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) | 1976-08-06 | 1977-02-05 | 1977-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-06 | 1981-02-05 | 1981-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-06 | 1985-02-05 | 1985-08-07 | $7700.00 | Window Closed / Lapsed |