| 摘要 |
PROBLEM TO BE SOLVED: To detect which LEDs are disconnected without lighting the LEDs.SOLUTION: A control device is provided including a plurality of LED arrays connected in parallel to one another, each of the plurality of LED arrays including LEDs connected in series and resistance elements 5 connected in series to the LEDs and having resistance values different from each other, a voltage supply circuit 2 for supplying voltage to the LED arrays, a switching element TR1 interposed between the LED arrays and a ground, a voltage detection circuit 3 having an end connected between the switching element and the LED arrays, and a capacitor C1 having an end connected between the switching element and the LED arrays and the other end connected to the ground. In the control device, the switching element is made a connection state, a command signal for supplying voltage for lighting the LEDs is output to the voltage supply circuit to light the LEDs, the switching element is made a cut-off state, and a command signal for supplying rectangular wave pulse voltage having a pulse width not to light the LEDS is output to the voltage supply circuit, thereby specifying disconnected LED arrays on the basis of a voltage value read from the voltage detection circuit. |
