| 摘要 |
PROBLEM TO BE SOLVED: To solve a problem of a lighting device which is configured to be divided into a power supply unit and a light emission unit and needs to apply a voltage of a forward drop voltage (VF) or more to both the ends of LED at the light emission time, the problem being as follows: when the voltage is set to zero under lights-out, a divided voltage when a lighting switch is turned on cannot be input to a comparator, and thus a voltage of not more than VF is applied; however, the voltage is not less than VF under lighting of LED whereas the voltage is not more than VF under lights-out, so that a comparison voltage input to the comparator greatly varies between the lighting and lights-out state of LED and thus turn-on/off of the switch cannot be detected.SOLUTION: A voltage to be applied to LED is used as voltage from which a reference voltage to be input to a reference voltage input unit is generated.SELECTED DRAWING: Figure 2 |
