Sound motion picture camera
US4134649A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 16, 1977 |
| Grant date | Jan 16, 1979 |
| Priority date | — |
| Expiry date | Mar 16, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B1/60
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A sound motion picture camera having a monitor circuit for applying to an earphone an audio signal which is being recorded on the film is capable of warning of the exhaustion of the film through the earphone. A switch responsive to a mechanism for detecting the exhaustion of the film applies a signal from an oscillator to the earphone or actuates an oscillator connected to the earphone, to provide the warning when the film has been nearly exhausted or has been completely exhausted. A switching device periodically interrupts the oscillating electric signal so that a warning sound can be heard intermittently through the earphone. A delay circuit interrupts the actuation of the oscillator to cease the oscillating electric signal when a predetermined time has passed after the detection of the exhaustion of the film.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.