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公开(公告)号:JP2002351417A
公开(公告)日:2002-12-06
申请号:JP2001156177
申请日:2001-05-24
Applicant: IBM
Inventor: SAKURAI TAKAAKI , WATANABE YOSHIAKI , YANA TOSHIYUKI , KARUBE SATOSHI
Abstract: PROBLEM TO BE SOLVED: To provide a liquid crystal driving power supply circuit in which a driving power supply voltage to be supplied to a driver circuit is precisely generated by employing a low precision reference voltage generating circuit. SOLUTION: A driving power supply circuit 11 consists of a DC/DC converter 34 which generates a voltage having a size based on oscillating signals VOUT from a power supply voltage Vcc of the circuit 11 and outputs the generated voltage as a driving power supply voltage Vdcdc , a stable power supply circuit 60 which generates a most significant reference potential Vref H used to generate a gradation voltage in a driver circuit, a comparison section 46 which computes the difference between the voltage Vdcdc and the potential Vref H and outputs the computed difference as a difference voltage, an internal reference voltage generating section 42 which generates an internal reference voltage VREF having a prescribed size, an error amplifying section 44 which computes the difference between a reference voltage that is determined by the generated voltage VREF and the difference voltage and a PWM converting section 32 which outputs the signals VOUT in accordance with the difference.