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

IPC: G02F1/133 ,  G09G3/20 ,  G09G3/36 ,  H02M3/155

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.