CIRCUIT FOR DRIVING LIGHT-EMITTING DEVICE

PROBLEM TO BE SOLVED: To provide a light emitting device driving circuit which can detect defective light-emitting devices, without consuming more electric power. SOLUTION: The light-emitting device driving circuit has such a structure that four LEDs 23 for magenta (hereinafter, to be called "M...

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Bibliographic Details
Main Author KATSUMA NOBUO
Format Patent
LanguageEnglish
Published 21.04.2005
Edition7
Subjects
BASIC ELECTRIC ELEMENTS
CORRECTION OF TYPOGRAPHICAL ERRORS
ELECTRIC HEATING
ELECTRIC LIGHTING NOT OTHERWISE PROVIDED FOR
ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
ELECTRICITY
i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME
LINING MACHINES
MEASURING
MEASURING ELECTRIC VARIABLES
MEASURING MAGNETIC VARIABLES
PERFORMING OPERATIONS
PHYSICS
PRINTING
SELECTIVE PRINTING MECHANISMS
SEMICONDUCTOR DEVICES
STAMPS
TESTING
TRANSPORTING
TYPEWRITERS
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Summary:PROBLEM TO BE SOLVED: To provide a light emitting device driving circuit which can detect defective light-emitting devices, without consuming more electric power. SOLUTION: The light-emitting device driving circuit has such a structure that four LEDs 23 for magenta (hereinafter, to be called "M"), an LED 24 for displaying which emits red-color light, and a constant-current circuit 27 for stabilizing currents in these LEDs 23 and 24, are connected in series to form a group 26; and that a driving power supply 31 supplies power to a plurality of such a group 26, in parallel. When none of the LEDs 23 for M in any group 26 has a disconnection defect, current is caused to flow in the LED 24 for displaying, and hence the LED 24 for displaying is lighted up red. However, when either of the groups 26 includes at least one LED 23 for M which has a disconnection defect, no current is caused to flow in the LED 24 for displaying, and hence the LED 24 for displaying is not lighted up. By this method, the group 26, which includes at least one LED 23 for M which has a disconnection defect, if any, can be specified, facilitating decision about repairing. COPYRIGHT: (C)2005,JPO&NCIPI
Bibliography:Application Number: JP20030338237