Patent ID: 8729821
Filing Date: 2014-05-20
Classification: H05B,Y02B

Abstract:
1. A semiconductor light source lighting circuit comprising: a transistor and a current detection resistor in series in a semiconductor light source current supply path; a control circuit arranged to control the transistor so as to decrease any difference between a voltage occurring at the current detection resistor and a reference voltage during operation of the semiconductor light source lighting circuit; and a bypass resistor arranged to establish a bypass path for current supplied to a semiconductor light source, wherein a first end of the bypass path is located at a connection node between the transistor and the semiconductor light source; wherein the current is divided such that a portion of the current flows into the transistor and another portion of the current flows into the bypass resistor when an input voltage to the semiconductor light source lighting circuit is within an operation range; and wherein the operation range is the range of values for the input voltage over which the size of the current flowing in the transistor changes according to changes in the input voltage.