| 摘要 |
PROBLEM TO BE SOLVED: To make an arrangement position of a backlight light source and a drive circuit visible at once when the backlight light source is in trouble. SOLUTION: The backlight light source drive circuit 3 is provided with a shunt resistor R for detecting a tube current I, and a protection signal output circuit 34 for outputting a PROTECTION SIGNAL S2 when the tube current falls below a given threshold value. The protection signal output circuit 34 is provided with an LED lighting circuit 35 to which a power source V2 is supplied at all times from a power source circuit 2. A switching element control part 33 turning on/off a switching element 32 turns off the switching element 32 in response to a signal S1 for turning off as a standby state when the signal S2 is generated. When the switching element 32 is turned off, an oscillation operation is stopped. At the standby state, the backlight light source drive circuit or the backlight light source with the tube current I fallen can be made visible as an LED 350 in the circuit is lit. COPYRIGHT: (C)2007,JPO&INPIT |
