| 摘要 |
PROBLEM TO BE SOLVED: To prevent the brightness of a light emitting diode from being affected by the voltage of a battery and maintain the brightness at a fixed level without using a booster circuit, by detecting the voltage of a power supply, intermittently turning on a switch element to light the light emitting diode, and increasing the ratio of the light emitting diode being turned on with the reduction of the voltage of the power supply. SOLUTION: When a microcomputer 1 commands to enter into a previously set status by a signal from each part of a gas apparatus, for instance, a status where a burner is lighted, a transistor 4 is turned on and a light emitting diode 3 is lighted, and where the burner is turned off, the transistor 4 is turned off and the light emitting diode 3 is turned off. Instead of using a booster circuit, the voltage of a power supply 2 is monitored and sufficient brightness can be obtained when the voltage is sufficiently high even when a conduction time is short. Therefore, an on signal from the microcomputer 1 to the transistor 4 is converted into a pulse signal of a prescribed frequency or more, and the on-time is shortened and the off-time is lengthened. When the voltage of the power supply 2 reduces, the on-time, i.e., light emitting time, is lengthened, preventing brightness deterioration. Thus, the brightness of the light emitting diode 3 is prevented from being affected by the variation of the power supply voltage without using a booster circuit. |
