# US 4,395,658 A · Proper light emission indicating device for computer flash device

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- Number: US 4,395,658 A
- Document ID: US4395658A
- Status: Granted
- Kind: A
- Application number: 06/181,675
- Filed: 1980-08-27
- Granted: 1983-07-26
- Earliest claimed: 1979-08-31
- Assignees: Canon Kabushiki Kaisha
- Inventors: Tadashi Okino
- Web page: https://patentgrep.com/patent/US4395658A

## CPC

- H05B 41/325: {by measuring the incident light}
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL

## Abstract

In the disclosed device, a sensor produces a corroborating signal when a computer flash unit emits a flash proper for an exposure. A timer energizes an indicator for a predetermined time in response to the corroborating signal. When the sensor produces a subsequent corroborating signal in response to another flash, while the indicator is energized, a reset device resets the timer. According to one embodiment of the invention, an overriding arrangement connected to the timer nullifies the operation of the timer a predetermined time after a flash emission.

## Claims

### Claim 1

An indicating device for a computer flash unit comprising:
sensing means for producing a confirmation signal when a flash causing a proper exposure has been emitted;
indicating means for producing a signal;
timing means for energizing the indicating means for a predetermined time interval in response to a confirmation signal;
reset means for resetting the timing means when a confirmation signal occurs during energization of the indicating means by said timing means; and
overriding means connected to said timing means to nullify the operation of the timing means when a predetermined time has elapsed after initiation of a flash.

### Claim 2 (depends on 1)

An indicating device according to claim 1, wherein said overriding means includes a timer circuit which begins to start a timing operation in response to initiation of the flash.