| 摘要 |
PROBLEM TO BE SOLVED: To provide a lighting apparatus which can set up a maximum light-emitting luminance of a light-emitting diode highly even if a light source of an unstable impressing voltage is used. SOLUTION: The lighting apparatus controls emission of a light-emitting diode (LED)1 by changing a switching on/off of a transistor Q1 and includes a fixed voltage circuit 2 to control a voltage impressed from a power source Vb to the light-emitting diode 1 below a predetermined value, a voltage detecting means 3 to detect a voltage of the power source Vb and a controlling means 4 to keep light-emitting luminance of the light-emitting diode 1 at approximately the same level by inputting a drive wave signal at a first duty cycle to the transistor Ql in case a voltage value of the power source Vb detected by the voltage detecting means is more or larger than the above predetermined value, and by inputting the above drive wave signal at a second duty cycle in case the voltage value of the power source Vb is smaller or lower than the above predetermined value. COPYRIGHT: (C)2007,JPO&INPIT |
