| 摘要 |
PROBLEM TO BE SOLVED: To provide a display device having a battery as its power source, capable of restraining flickering of a light emitting element, irrespective of the type of the battery when the voltage of a power source consisting of the battery changes rapidly. SOLUTION: When an appliance plug switch SW is turned on, a control part 3 turns on/off a solenoid valve 5 for temperature control, and compares the voltage difference between both detected voltages of a power source 1 by a voltage detecting circuit 4 under respective conditions with a prescribed threshold voltage to discriminate the type of a battery. First and second control signals, associated with the on/off operation of the solenoid valve 5 for temperature control, are determined so that current flowing through a light-emitting diode, LED 6 may be almost constant, irrespective of whether the solenoid valve 5 for temperature control is turned on or off according to the type of a battery. An LED drive circuit 7 is controlled by the second control signal to light the light-emitting diode 6. In turning on the solenoid valve 5 for temperature control, the first control signal starts controlling of the LED drive circuit 7, while in turning off the solenoid valve 5 for temperature control, the second control signal starts controlling of the LED drive circuit 7.
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