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Patent Searching and Data


Title:
PHOTOMETRIC CIRCUIT
Document Type and Number:
Japanese Patent JPS5975233
Kind Code:
A
Abstract:

PURPOSE: To project or store automatically a strobe light emission part by generating a difference in brigthness level at which an operation is performed according to the variation state of subject brightness and providing the photometric operation with hysteresis.

CONSTITUTION: When a specific voltage is supplied from a power source terminal 1 while the strobe light emission part is at a storage position, a photocurrent flows through resistances 3 and 4 since a switch 10 is off. A comparator 8 compares the level of the voltage drop generated across the resistances 3 and 4 by the photocurrent with the voltage level of a reference power source 9 to lower the subject brightness; and the voltage drop level drops at hand-shake limit brightness to invert the output from H to L. When the strobe light emission part is moved from the storage part to a projection position to turn on the switch 10, the specific voltage applied to the power source terminal 1 is supplied between the base and emitter of a transistor 7, which turns on to form a short circuit across the resistance 4.


Inventors:
NIWA KATSUHISA
IKEDA TAKAHIRO
Application Number:
JP18694382A
Publication Date:
April 27, 1984
Filing Date:
October 25, 1982
Export Citation:
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Assignee:
WEST ELECTRIC CO
International Classes:
G01J1/44; G03B7/16; G03B15/05; (IPC1-7): G01J1/44; G03B15/05