| 摘要 |
<p>A display LED drive circuit configured in such a manner that, for example, a constant current circuit, a green display LED circuit, and a red display LED circuit are connected in series and a resistor circuit having a resistor that generates a potential difference identical to the respective display LEDs is connected in parallel to the respective LED circuits, a corresponding switching element of the display LED circuit and a corresponding switching element of the resistor circuit connected in parallel are controlled to be opened and closed in opposite ways, another route connected to a source circuit in parallel is connected to the constant current circuit, a blue display LED circuit connected in parallel to the resistor circuit as described above, and a constant voltage diode in series, and a predetermined voltage is derived from an output terminal by the constant voltage diode and supplied to a control circuit. In this arrangement, the number of constant current circuits can be reduced, and hence reduction of current consumption and cost, and improvement of the power source usage efficiency are achieved.</p> |
