Warning circuit in an auto-controlled flashlight photographing device
US4193677A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 28, 1978 |
| Grant date | Mar 18, 1980 |
| Priority date | — |
| Expiry date | Jul 28, 1998 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B2215/0514
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A warning circuit in an auto-controlled flashlight device comprises a first circuit for generating a voltage corresponding to the guide number determined by film sensitivity, aperture value and object distance, a second circuit for generating a maximum voltage corresponding to the maximum value of the quantity of light emitted by the auto-controlled speed light and a minimum voltage corresponding to the minimum value of the quantity of light emitted by the auto-controlled speed light, comparator means for comparing the output voltage of said first circuit with said maximum voltage and said minimum voltage and generating a high-level signal when the output voltage is in the range of said maximum voltage value and said minimum voltage value but generating a low-level signal when the output voltage is beyond the range, and a light emitting display element turned on in response to the high-level signal from the comparator means.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.