US3700319A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control circuit for single frame film advance audio projector
Assignee: OPTISONICS CORP
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Filing: 1971-01-12
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Granted: 1972-10-24
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Expires: 1991-01-12
Abstract
Abstract A control circuit for an audio-visual projector of the type wherein a dual track magnetic tape recording provides an audio presentation and control signal bursts for advancing a filmstrip in single frame sequence in predetermined synchronism with said audio presentation. The projector is turned on by manual operation of a momentary contact switch; this renders conductive a main semiconductive switch which energizes the projector lamp, the tape drive motor, and, via a diode, a first circuit control bulb and a storage capacitor in parallel with said bulb. Light from the bulb is sensed by a first photoconductor in parallel with the manual switch. The first photoconductor assumes a lowered impedance, thereby to maintain the main semiconductive switch (and hence the projector lamp, tape drive motor, and first bulb) energized so that the first frame of the filmstrip is projected and the audio presentation is heard. Each burst from the control track of the audio tape advances the filmstrip one frame as follows: the burst (after amplification) briefly energizes a second circuit control bulb; this illuminates (and lowers the impedance of) a second photoconductor, thereby to render conductive a second semiconductive switch which energizes the projector''s geneva film drive mechanism. The second semiconductive switch shunts the first circuit control bulb and diode but does not extinguish the first bulb when turned on briefly because the capacitor, having been charged, supplies current to maintain the first bulb on during film advance intervals. However at the end of the audio visual presentation, a long control burst is provided which turns on the second semiconductive switch long enough to cause the capacitor''s charge to dissipate, whereby the first control bulb turns off, interrupting the latching action of the circuit associated with the main semiconductive switch so as to turn off the entire projector.
Inventors
- 👤 Harold Gallina
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 12:24
CPC Classifications
G; G03; G03B; G03B19/00; G03B19/18; G03B31/00; G03B31/02
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
145 words
In combination: a. a source of electrical energy, an electrical load, and switch means having a control terminal for selectively connecting said source to said load in response to a predetermined electrical input at said control terminal, b. a source of light connected to receive energy from said electrical source and thereby provide light output when said switch connects said electrical source to said load, c. electrical storage means connected to accumulate and store a charge when said light source receives electrical energy, d. light responsive means positioned to receive light when provided by said light source and in response thereto supply said predetermined electrical input to said control terminal of said switch means, and realtively e. means for selectively substantially interrupting the supply of electrical energy from said electrical source to said light source without interrupting the supply of electrical energy to said load.
Claim 2
Dependent Claim
145 words
In combination: a. a source of electrical energy, an electrical load, and switch means having a control terminal for selectively connecting said source to said load in response to a predetermined electrical input at said control terminal, b. a source of light connected to receive energy from said electrical source and thereby provide light output when said switch connects said electrical source to said load, c. electrical storage means connected to accumulate and store a charge when said light source receives electrical energy, d. light responsive means positioned to receive light when provided by said light source and in response thereto supply said predetermined electrical input to said control terminal of said switch means, and realtively e. means for selectively substantially interrupting the supply of electrical energy from said electrical source to said light source without interrupting the supply of electrical energy to said load.
Claim 3
Dependent Claim
64 words
The combination of claim 1 wherein said (e) means comprises means for interrupting the supply of electrical energy to said light source for two alternative intervals, one interval being long anough to allow said storage means to discharge sufficiently to extinguish said light source, and the other interval being shorter than necessary for said storage means to discharge sufficiently to extinguish said light source.
Claim 4
Dependent Claim
17 words
The combination of claim 1 wherein said (e) means comprises means for selectively shunting said light source.
Claim 5
Dependent Claim
52 words
The combination of claim 1 wherein said source of electrical energy is an alternating current source, said switch means is a triac, said source of light is connected to one terminal of said triac via a diode, and said storage means is a capacitor connected in shunt with said source of light.
Claim 6
Dependent Claim
69 words
The combination of claim 2 wherein said load comprises an optical projector and an audio playback unit, and wherein said (e) means comprises a recording in said playback unit arranged to supply alternatively a relatively short and a relatively long control signal, and means responsive to said control signals for interrupting said supply of electrical energy for intervals substantially equal to the temporal width of each received control signal.
Claim 7
Dependent Claim
233 words
In an audio projection apparatus of the type wherein a recorded control signal is provided in synchronism with an audio-visual presentation for sequencing the visual part of said presentation by means of a relatively short control signal, and turning off said apparatus when said presentation is terminated by means of a relatively long control signal, a control circuit comprising: a. a source of electrical energy and an electronic switch for selectively connecting said electrical source to operate the projection lamp and audio playback unit of said apparatus in response to a predetermined electrical input to said electronic switch, b. light means connected to receive energy from said electrical source and thereby produce light in response to the connection of said electrical source to said lamp and said playback unit, c. electrical storage means connected to accumulate and store a charge in response to the connection of said electrical source to said lamp and said playback unit, d. light responsive means positioned to receive light when provided by said light source and, in response thereto, supply said predetermined electrical input to said electronic switch, and e. means responsive to said control signals for selectively substantially interrupting the supply of energy from said electrical source to said light means without interrupting the supply of electrical energy to said lamp and playback unit for respective intervals substantially equal to the temporal width of each control signal.
Claim 8
Dependent Claim
233 words
In an audio projection apparatus of the type wherein a recorded control signal is provided in synchronism with an audio-visual presentation for sequencing the visual part of said presentation by means of a relatively short control signal, and turning off said apparatus when said presentation is terminated by means of a relatively long control signal, a control circuit comprising: a. a source of electrical energy and an electronic switch for selectively connecting said electrical source to operate the projection lamp and audio playback unit of said apparatus in response to a predetermined electrical input to said electronic switch, b. light means connected to receive energy from said electrical source and thereby produce light in response to the connection of said electrical source to said lamp and said playback unit, c. electrical storage means connected to accumulate and store a charge in response to the connection of said electrical source to said lamp and said playback unit, d. light responsive means positioned to receive light when provided by said light source and, in response thereto, supply said predetermined electrical input to said electronic switch, and e. means responsive to said control signals for selectively substantially interrupting the supply of energy from said electrical source to said light means without interrupting the supply of electrical energy to said lamp and playback unit for respective intervals substantially equal to the temporal width of each control signal.
Claim 9
Dependent Claim
44 words
The control circuit of claim 6 wherein said electrical source is an alternating current sourcE, said electronic switch is a triac and said light means and said storage means are connected in a parallel circuit which is connected to said triac via a diode.
Claim 10
Dependent Claim
42 words
The control circuit of claim 7 wherein said (e) means comprises (1) a second triac in shunt with said parallel circuit and said diode and (2) means for rendering said second triac conductive for the duration of each of said control signals.
Claim 11
Dependent Claim
54 words
The control circuit of claim 8 wherein said means for rendering said second triac conductive comprises a second light means for providing light for the duration of each control signal and a second light responsive means connected to receive light from said second light means, and, in response thereto, render said second triac conductive.
Claim 12
Dependent Claim
29 words
The control circuit of claim 7 wherein said light responsive means is connected between a control electrode of said triac and said projection lamp and said audio playback unit.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-10-24 | 1976-04-24 | 1976-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-24 | 1980-04-24 | 1980-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-24 | 1984-04-24 | 1984-10-24 | $7700.00 | Window Closed / Lapsed |