Patent ID: 8797246

Claim:
A voltage generating circuit for generating a providing voltage to a drive circuit comprising: a first and a second variable resistances for adjusting said providing voltage; a first operational amplifier outputting a high level of said providing voltage, and a non-inversion input thereof connected to a variable portion of said second variable resistance; a second operational amplifier outputting a low level of said providing voltage, and a non-inversion input thereof connected to a variable portion of said second variable resistance; a first resistance connecting a variable portion of said first variable resistances to an inversion input of said first operational amplifier; a second resistance wherein one terminal of said second resistance connected to said inversion input of said first operational amplifier, and the other terminal of said second resistance connected to output of said first operational amplifier; a third resistance connecting a constant voltage supply to an inversion input of said second operational amplifier; a fourth resistance wherein one terminal of said fourth resistance connects to a inversion input of said second operational amplifier, and the other terminal of said fourth resistance connects to an output of said second operational amplifier; wherein total resistance of said first variable resistance is a resistance value of one third or less of at least one of the total resistance of said second variable resistance and resistance of said first operational amplifier, said second operational amplifier, said first resistance, said second resistance, said third resistance, and said fourth resistance; and wherein said first and second variable resistances adjust a low level of said providing voltage and a voltage difference between a high level and the low level of said providing voltage.