US 5,327,070 AGranted

Power supply circuit for driving a light emitting element

AssigneeSeikosha Co., Ltd.

InventorsYoichi Seki, Shinichi Endo, Hiroyuki Saito, Akira Ito, Michio Kawai

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Abstract

In a step-up circuit for causing the emission of light of a distance measuring light emitting element, the step-up circuit outputs a step-up voltage from one terminal of a step-up capacitor. A step-up voltage level changeover circuit applies a step-up voltage to the capacitor every time the distance measuring light emitting element emits light that is higher than the step-up voltage in the normal state. The number of parts is reduced by eliminating a separate capacitor for light emission, the space for the circuit is reduced by using the capacitor having a small capacity, the soldering steps for fabrication of the circuit are automated; and the costs for assembly are ameliorated owing to the automation.

Claims9

Dependent claims

A power supply circuit for driving a light emitting element, comprising:

a step-up capacitor having two terminals;
a step-up circuit connected to said step-up capacitor to apply a step-up voltage of a first level thereto;
a step-up voltage level changeover means connected to both of the terminals of said step-up capacitor for changing over the step-up voltage level applied to said step-up capacitor to a second step-up voltage level that is higher than the first step-up voltage level;
a distance measuring light emitting element connected to both terminals of said step-up capacitor for selectively receiving the voltages of first and second step-up voltage applied thereto;
an operating means generating a step-up voltage changeover signal which is the first step-up voltage when said distance measuring light emitting element does not emit and the second step-up voltage when said light emitting element emits;
and
a control means connected between said operating means and said step-up voltage changeover means, and communicating said step-up voltage to said changeover signal.

4 more elements

A power supply circuit for driving a light emitting element, comprising:

a step-up capacitor having two terminals;
a step-up circuit connected to said step-up capacitor to apply a step-up voltage thereto;
a step-up voltage level changeover means connected to said step-up circuit for controlling said step-up to selectively apply step-up voltages of first and second levels to said step-up capacitor;
a distance measuring light emitting element, and means connecting said light emitting element to the terminals of said step-up capacitor to receive voltages applied to said step-up capacitor;
an operating means generating a first step-up voltage changeover signal when said distance measuring light emitting element does not emit and second step-up voltage changeover signal when said light emitting element emits;
and
means connected to apply said first an second step-up voltage changeover signals to said step-up voltage level changeover means;
said step-up voltage level changeover means being responsive to receipt of said first step-up voltage changeover signal for controlling said step-up circuit to apply said voltage of said first level to said step-up capacitor, and means responsive to receipt of said second step-up voltage changeover signal for controlling said step-up circuit to apply said voltage of said second level to said step-up capacitor.

5 more elements

Dependencies are inferred from the claim text.