Patent ID: 7830097

Claim:
A light emitting diode driving semiconductor circuit that is connected to a light emitting diode block including a rectifier circuit that rectifies an alternating-current voltage and one or more light emitting diodes to which a voltage output from the rectifier circuit is applied to emit light, the light emitting diode driving semiconductor circuit comprising: a junction type FET to which the output voltage of the rectifier circuit is applied directly or by way of the light emitting diode; a first switching element that is connected between the light emitting diodes and a ground potential; and a control circuit block that controls on/off of the first switching element, the control circuit block comprising: an input terminal that inputs an output voltage of the junction type FET; an input voltage detection circuit that detects the voltage output from the rectifier circuit and compares the detected voltage with a predetermined value to output a light emitting signal or a extinction signal for controlling emission or extinction of the light emitting diodes; a current detection circuit that detects a current flowing into the first switching element; and a control circuit that intermittently controls on/off of the first switching element at a predetermined oscillating frequency based on an output signal of the current detection circuit so that the current flowing into the light emitting diode is constant while the input voltage detection circuit is outputting the light emitting signal, a regulator that is connected to the input terminal and receives the output voltage of the junction type FET to output a constant reference voltage when the output voltage of the junction type FET is greater than or equal to a predetermined value, a start/stop circuit, wherein the control circuit block is driven by applying the output voltage of the junction type FET to the input terminal, each circuit in the control circuit block is driven by applying the constant reference voltage, the regulator outputs a start signal or a stop signal for the on/off control of the first switching element based on whether or not the output voltage of the junction type FET is greater than or equal to the predetermined value, and the start/stop circuit outputs the stop signal to the control circuit when the regulator outputs the stop signal, and outputs the light emitting signal or the extinction signal of the input voltage detection circuit to the control circuit when the regulator outputs the start signal.