Dot matrix type liquid crystal display apparatus

• US 5,638,087 A
• Filed: 06/24/1994
• Issued: 06/10/1997
• Est. Priority Date: 01/11/1993
• Status: Expired due to Term

• Current Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation), Tottori Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Sanyo Electric Company Limited (Panasonic Holdings Corporation), Tottori Sanyo Electric Company Limited (Panasonic Holdings Corporation)
• Inventors: Tanaka, Toshihiko, Iwasaki, Shoji, Kobayashi, Norimitsu
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): LAO, LUNYI
• Application Number:
  US08/265,626
• Time in Patent Office: 1,082 Days
• Field of Search: 323/280, 330/99, 330/100, 330/105, 330/252, 330/282, 330/260, 330/254, 330/228, 345/87, 345/98, 345/94, 345/211, 345/212, 345/208, 359/55, 359/56, 359/59
• US Class Current: 345/87
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers

Abstract

A liquid crystal display apparatus is driven by a voltage averaging method. The display apparatus is provided with voltages via a scanning circuit and a driver circuit from a power supplying circuit. The power supplying circuit has a voltage compensating circuit which is provided with an operational amplifier whose first input terminal is provided with a predetermined voltage and whose second input terminal is connected to an output terminal thereof through a resistor, an impedance circuit connected between the output terminal of the operational amplifier and an output terminal of the power supplying circuit, and feedback circuit for feeding back both of an alternating current component and a direct current component of an output of the impedance circuit to the second input terminal of the operational amplifier.

Claims

1. A liquid crystal display apparatus comprising:

a liquid crystal cell including a first electrode group and a second electrode group which intersect each other;

a scanning circuit connected to the first electrode group;

a driver circuit connected to the second electrode group;

a power supplying circuit for providing to the scanning circuit and to the driver circuit a selecting voltage and a non-selecting voltage so that the liquid crystal cell is driven by a voltage averaging method; and

a voltage compensating circuit provided to the power supplying circuit for compensating for an output voltage of the power supplying circuit in accordance with a value of an output current of the power supplying circuit, said voltage compensating circuit comprising

an operational amplifier having a first input terminal, a second input terminal, and an output terminal, wherein a predetermined voltage is provided to the first input terminal,

an impedance circuit connected to the output terminal of the operational amplifier at one end and to an output terminal of the power supplying circuit at another end,

a first resistor connected to the second input terminal of the operational amplifier at one end and to a connection point of the output terminal of the operational amplifier and the impedance circuit at another end, and

feedback means for feeding back an output of the impedance circuit to the operational amplifier, said feedback means being connected to the output terminal of the power supplying circuit at one end and to the second input terminal of the operational amplifier at another end.

2. A liquid crystal display apparatus according to claim 1, wherein said feedback means includes a second resistor.

3. A liquid crystal display apparatus according to claim 2, wherein said impedance circuit includes a third resistor.

4. A liquid crystal display apparatus according to claim 2, wherein said impedance circuit includes a buffer.

5. A liquid crystal display apparatus according to claim 2, wherein said impedance circuit includes a buffer and a third resistor, said third resistor being connected to an output end of the buffer.

6. A liquid crystal display apparatus according to claim 1, wherein said feedback means includes a capacitor for feeding back an alternating current component of an output of the impedance circuit.

7. A liquid crystal display apparatus according to claim 6, wherein said impedance circuit includes a third resistor.

8. A liquid crystal display apparatus according to claim 6, wherein said impedance circuit includes a buffer.

9. A liquid crystal display apparatus according to claim 6, wherein said impedance circuit includes a buffer and a third resistor, said third resistor being connected to an output end of the buffer.

10. A liquid crystal display apparatus comprising:

a liquid crystal cell including a first electrode group and a second electrode group which intersect each other;

a scanning circuit connected to the first electrode group;

a driver circuit connected to the second electrode group;

a power supplying circuit for providing to the scanning circuit and to the driver circuit a selecting voltage and a non-selecting voltage so that the liquid crystal cell is driven by a voltage averaging method; and

a voltage compensating circuit provided to the power supplying circuit for compensating for an output voltage of the power supplying circuit in accordance with a value of an output current of the power supplying circuit, said voltage compensating circuit comprising

an operational amplifier having a first input terminal, a second input terminal, and an output terminal, wherein a predetermined voltage is provided to the first input terminal,

an impedance circuit connected to the output terminal of the operational amplifier at one end and to an output terminal of the power supplying circuit at another end,

a first resistor connected to the second input terminal of the operational amplifier at one end and to a connection point of the output terminal of the operational amplifier and the impedance circuit at another end, and

feedback means for feeding back both of an alternating current component and a direct current component of an output of the impedance circuit to the operational amplifier, said feedback means being connected to the output terminal of the power supplying circuit at one end and to the second input terminal of the operational amplifier at another end.

11. A liquid crystal display apparatus according to claim 10, wherein said feedback means includes a capacitor for feeding back the alternating current component and a second resistor for feeding back the direct current component.

12. A liquid crystal display apparatus according to claim 10, wherein said impedance circuit includes a third resistor.

13. A liquid crystal display apparatus according to claim 10, wherein said impedance circuit includes a buffer.

14. A liquid crystal display apparatus according to claim 10, wherein said impedance includes a buffer and a third resistor, said third resistor being connected to an output end of the buffer.