Title:
LED DRIVING CIRCUIT
Document Type and Number:
Japanese Patent JPH0425080
Kind Code:
A
Abstract:
PURPOSE:To suppress the wasteful consumption of electric current to be minimum by outputting control signals at the prescribed logical levels for a first and a second switching means so as to control the turning on and off of each pair of LEDs. CONSTITUTION:When turning on an LED 27b, a control signal at a logical level '1' is impressed on the non-inversion input terminal of an AND circuit 24 from the control signal output terminal 31 of a control signal output part 29. Then, the output from the AND circuit 24 becomes the opposite phase of a clock signal inputted to the inversion input terminal of the AND circuit 24. At this point, when a voltage signal at a logical level '0' is impressed on the cathode terminal side of the LED 27b (the anode terminal side of an LED 27a) from a common driving circuit 21, since a clock signal at the logical level '0' is impressed on the inversion input terminal of the AND circuit 24 in synchronism with the impression of the voltage signal. The logical level of the output of the AND circuit 24 becomes '1'. When the logical level of the output of the AND circuit 24 is at '1', regardless of the logical level of the output of the AND circuit 23, the logical level of the output of an OR circuit 25 becomes '1'. Namely, a forward direction bias voltage becomes effective for the LED 27b and the LED 27b is turned on.
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Inventors:
SHIRAKAWA HIROSHI
Application Number:
JP12591390A
Publication Date:
January 28, 1992
Filing Date:
May 16, 1990
Export Citation:
Assignee:
TOSHIBA CORP
International Classes:
H01L33/08; (IPC1-7): H01L33/00
Attorney, Agent or Firm:
Kazuo Sato (3 others)
Next Patent: JPH0425081