Gray scale voltage generating circuit
View Patent ↗A gray scale voltage generating circuit includes a first resistor ladder circuit, connected between a high voltage power supply terminal and a low voltage power supply terminal and having nodes for outputting respective reference voltages, a second resistor ladder circuit, connected between the high voltage power supply terminal and the low voltage power supply terminal, and plural voltage follower circuits, connected between the respective nodes of the second resistor ladder circuit and the respective nodes of the first resistor ladder circuit with first resistor provided between the n/2'th node voltage and the high voltage power supply terminal and a second resistor provided between the n/2+1'th node voltage and the low voltage power supply terminal.
1. A gray scale voltage generating circuit comprising:
a first resistor ladder circuit for outputting first to n'th reference voltages from n nodes thereof, n being an even number, said n nodes being arranged between a high voltage power supply terminal and a low voltage power supply terminal;
a second resistor ladder circuit including n nodes arranged between an output terminal of a constant voltage generating circuit and said low voltage power supply terminal;
first to n'th voltage follower circuits respectively arranged between said n nodes of said second resistor ladder circuit and corresponding ones of said n nodes of said first resistor ladder circuit;
a first resistor connected between a n/2'th node as counted from the low voltage power supply terminal side of said first resistor ladder circuit and said high voltage power supply terminal; and
a second resistor connected between a n/2+1'th node as counted from the low voltage power supply terminal side of said first resistor ladder circuit and said low voltage power supply terminal.
2. The gray scale voltage generating circuit according to claim 1 further comprising:
a third resistor connected between a n'th node as counted from said low voltage power supply terminal of said first resistor ladder circuit and said high voltage power supply terminal; and
a fourth resistor connected between the first node as counted from said low voltage power supply terminal of said first resistor ladder circuit and said low voltage power supply terminal.
3. The gray scale voltage generating circuit according to claim 1 , wherein, in said first resistor ladder circuit, said n/2'th node and said n/2+1'th node are not connected via a resistor.
4. A display apparatus including a driver, said driver comprising:
the gray scale voltage generating circuit as set fourth in claim 1 ; and
a digital-to-analog converter receiving output voltages from said gray scale voltage generating circuit and outputting a signal voltage corresponding to an input digital data signal;
wherein said first resistor ladder circuit and the voltage follower circuits of the gray scale voltage generating circuit is provided in said driver and said second resistor ladder circuit of the gray scale voltage generating circuit is provided outside said driver.
5. A display apparatus including a driver, said driver comprising:
the gray scale voltage generating circuit as set fourth in claim 1 ; and
a digital-to-analog converter receiving output voltages from said gray scale voltage generating circuit and outputting a signal voltage corresponding to an input digital data signal;
wherein said first resistor ladder circuit of the gray scale voltage generating circuit is provided in said driver; and said voltage follower circuits and said second resistor ladder circuit are provided outside said driver.
6. A gray scale voltage generating circuit comprising:
a first resistor ladder circuit for outputting first to n'th reference voltages from n nodes thereof, n being an even number, said n nodes being arranged between a high voltage power supply terminal and a low voltage power supply terminal;
a second resistor ladder circuit including n nodes arranged between an output terminal of a constant voltage generating circuit and said low voltage power supply terminal;
first to n'th voltage follower circuits arranged between n nodes of said second resistor ladder circuit and corresponding n nodes of said first resistor ladder circuit;
a first current source arranged between a n/2'th node of said first resistor ladder circuit as counted from the low voltage power supply terminal side and said high voltage power supply terminal; and
a second current source arranged between a n/2+1'th node of said first resistor ladder circuit as counted from the low voltage power supply terminal side of said first resistor ladder circuit and said low voltage power supply terminal.
7. The gray scale voltage generating circuit according to claim 6 further comprising:
a third current source connected between a n'th node as counted from the low voltage power supply terminal side of said first resistor ladder circuit and said high voltage power supply terminal; and
a fourth current source connected between the first node as counted from the low voltage power supply terminal side of said first resistor ladder circuit and said low voltage power supply terminal.
8. A display apparatus including a driver, said driver comprising:
the gray scale voltage generating circuit as set fourth in claim 6 ; and
a digital-to-analog converter receiving output voltages from said gray scale voltage generating circuit and outputting a signal voltage corresponding to an input digital data signal;
wherein said first resistor ladder circuit and the voltage follower circuits of the gray scale voltage generating circuit is provided in said driver and said second resistor ladder circuit of the gray scale voltage generating circuit is provided outside said driver.
9. A display apparatus including a driver, said driver comprising:
the gray scale voltage generating circuit as set fourth in claim 6 ; and
a digital-to-analog converter receiving output voltages from said gray scale voltage generating circuit and outputting a signal voltage corresponding to an input digital data signal;
wherein said first resistor ladder circuit of the gray scale voltage generating circuit is provided in said driver; and said voltage follower circuits and said second resistor ladder circuit are provided outside said driver.