Title:
BACK LIGHT DEVICE FOR LIQUID CRYSTAL DISPLAY DEVICE
Document Type and Number:
Japanese Patent JP3486304
Kind Code:
B2
Abstract:
PROBLEM TO BE SOLVED: To prolong the using time of a battery power source by turning off a current supplied to a back light in the case the supplied power source voltage is lower than a reference voltage supplied from a stabilized power source.
SOLUTION: A comparator 12 compares the reference voltage value with the voltage value of the battery 9. As a result, when the voltage value of the battery 9 is larger than the reference voltage value, the comparator 12 transmits a signal H to the base of a transistor 13 and a CPU 1. As to the transistor 13, the base receives the signal H, a collector is turned on, a current from the battery 9 is transmitted to the back light 10 so as to turn on the back light 10, and an easy-to-view LCD screen can be obtained. When the voltage of the battery 9 is lower than the reference voltage in the case the comparator 12 performs comparison, a signal L is outputted from the comparator 12 to the base of the transistor 13 and the CPU 1, and a power source circuit supplying power source current to the back light 10 from the battery 9 is turned off, and the power source of the battery 9 can be saved.
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Inventors:
Masato Kanehara
Application Number:
JP20642296A
Publication Date:
January 13, 2004
Filing Date:
July 18, 1996
Export Citation:
Assignee:
Kawai Musical Instruments Mfg. Co., Ltd.
International Classes:
G02F1/133; F21V8/00; G02F1/13; G09G3/18; G10H1/18; (IPC1-7): G02F1/133; F21V8/00; G02F1/13; G09G3/18; G10H1/18
Domestic Patent References:
| JP272326A | ||||
| JP2195390A | ||||
| JP3233516A | ||||
| JP6120864A | ||||
| JP7253779A | ||||
| JP61119190U | ||||
| JP61179594U |
Attorney, Agent or Firm:
Kaoru Kawanami