发明人：MIZOGUCHI TADASHI 申请号：JP22617090
申请日：19900828
公开号：JPH04107888A
公开日：
19920409
摘要：PURPOSE:To always keep constant the quantity of light emitted from LED without relation to ambient temperature by storing a temperature compensating voltage value of the reference voltage for controlling a current and reading a temperature compensating voltage value corresponding to a measured value of ambient temperature sent from a temperature detecting means to control the reference voltage which determines an output current value of an LED driver. CONSTITUTION:A temperature information converted to a digital value is inputted to EEPROM 3 and content is read by designating an address. A value for compensating temperature characteristic of quantity of light emission of LED is previously written in EEPROM 3 using temperature information as an address. Digital temperature information read from EEPROM 3 is inputted to a D/A converter 4 and is then converted again to voltage value. An output voltage of the D/A converter 4 is inputted to a subtraction amplifier OP1 of a driver stage 5. An output voltage, namely temperature compensating reference voltage (VRO) of this D/A converter 4 corresponds to the conventional reference voltage (VR). Therefore, an operating current I of each LED of an LED array 6 is determined by reading VR as VRO with a resistor R.
申请人：NEC CORP
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