Voltage calibration circuit and related liquid crystal display device

• US 9,653,035 B2
• Filed: 04/23/2014
• Issued: 05/16/2017
• Est. Priority Date: 08/23/2013
• Status: Active Grant

• Current Assignee: Sitronix Technology Corporation
• Original Assignee: Sitronix Technology Corporation
• Inventors: Lin, Tsun-Sen, Liao, Min-Nan
• Primary Examiner(s): Blancha, Jonathan
• Application Number:
  US14/259,167
• Publication Number:
  US 20150054810A1
• Time in Patent Office: 1,119 Days
• Field of Search: 345 87-100, 345211
• CPC Class Codes: G09G 2310/06 Details of flat display driving waveforms
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers

Abstract

The present disclosure provides a voltage calibration circuit. The voltage calibration circuit includes a coupling voltage detection circuit and a common voltage circuit. The coupling voltage detection circuit is used for detecting a coupling voltage in an initial phase and generating a compensation voltage according to the coupling voltage. The common voltage circuit is used for adjusting a common voltage according to the compensation voltage and outputting the common voltage to a display module in a display phase.

Claims

1. A voltage calibration circuit for a display module, the display module comprising a plurality of pixel capacitors and a common voltage terminal, one end of each of the plurality of pixel capacitors electrically and directly connected to the common voltage terminal, the voltage calibration circuit comprising:

a coupling voltage detection circuit for detecting a coupling voltage in an initial phase and generating a compensation voltage according to the coupling voltage;

a common voltage circuit for adjusting a common voltage according to the compensation voltage and outputting the common voltage to the display module in a display phase; and

a switch, having one terminal connected to the common voltage terminal of the display module, and another terminal connected to the coupling voltage detection circuit or the common voltage circuit, such that the switch is configured to couple the display module to the coupling voltage detection circuit or the common voltage circuit;

wherein the initial phase is a time period after the display module is turned on but before any image has been displayed;

wherein the coupling voltage in the initial phase is a voltage difference on the common voltage terminal before and after an initial falling edge of gate signals of the display module.

2. The voltage calibration circuit of claim 1, wherein the switch couples the display module to the coupling voltage detection circuit in the initial phase.

3. The voltage calibration circuit of claim 1, wherein the switch couples the display module to the common voltage circuit in the display phase.

4. The voltage calibration circuit of claim 1 further comprising a switch coupled to a source driving circuit and the coupling voltage detection circuit, for coupling the display module to the source driving circuit or the coupling voltage detection circuit.

5. The voltage calibration circuit of claim 1 further comprising:

a first switch coupled to a source driving circuit and the coupling voltage detection circuit, for coupling the display module to the source driving circuit or the coupling voltage detection circuit.

6. The voltage calibration circuit of claim 1 further comprising a voltage setting unit coupled to the coupling voltage detection circuit and the common voltage circuit for setting a predetermined shift value for the common voltage.

7. A liquid crystal device (LCD) comprising:

a display module comprising a plurality of parasitic capacitances, a plurality of pixel capacitors and a common voltage terminal, wherein one end of each of the plurality of pixel capacitors is electrically and directly connected to the common voltage terminal;

a gate driving circuit for generating a plurality of gate signals;

a source driving circuit coupled to the display module for outputting a display voltage to the display module; and

a voltage calibration circuit comprising;

a coupling voltage detection circuit for detecting a coupling voltage in an initial phase and generating a compensation voltage according to the coupling voltage;

a common voltage circuit for adjusting a common voltage according to the compensation voltage and outputting the common voltage to the display module in a display phase; and

a switch, having one terminal connected to the common voltage terminal of the display module, and another terminal connected to the coupling voltage detection circuit or the common voltage circuit, such that the switch is configured to couple the display module to the coupling voltage detection circuit or the common voltage circuit;

wherein the initial phase is a time period after the display module is turned on but before any image has been displayed;

wherein the coupling voltage in the initial phase is a voltage difference on the common voltage terminal before and after an initial falling edge of gate signals of the display module.

8. A voltage calibration circuit for a display module, the display module comprising a plurality of pixel capacitors and a common voltage terminal, one end of each of the plurality of pixel capacitors electrically and directly connected to the common voltage terminal, the voltage calibration circuit comprising:

a coupling voltage detection circuit for detecting a coupling voltage in an initial phase and generating a compensation voltage according to the coupling voltage;

a source driving voltage circuit for adjusting a display voltage according to the compensation voltage and outputting the display voltage to the display module in a display phase; and

a switch, having one terminal connected to the common voltage terminal of the display module, and another terminal connected to the coupling voltage detection circuit or a ground terminal, such that the switch is configured to couple the display module to the coupling voltage detection circuit or the ground terminal;

wherein the initial phase is a time period after the display module is turned on but before any image has been displayed;

wherein the coupling voltage in the initial phase is a voltage difference on the common voltage terminal before and after an initial falling edge of gate signals of the display module.

9. The voltage calibration circuit of claim 8 further comprising a switch coupled to the coupling voltage detection circuit, for coupling the display module to a ground terminal or the coupling voltage detection circuit.

10. The voltage calibration circuit of claim 9, wherein the switch couples the display module to the coupling voltage detection circuit in the initial phase.

11. The voltage calibration circuit of claim 9, wherein the switch couples the display module to the ground terminal in the display phase.

12. The voltage calibration circuit of claim 8 further comprising a switch coupled to the source driving circuit and the coupling voltage detection circuit, for coupling the display module to the source driving circuit or the coupling voltage detection circuit.

13. The voltage calibration circuit of claim 8 further comprising:

a first switch coupled to the source driving circuit and the coupling voltage detection circuit, for coupling the display module to the source driving circuit or the coupling voltage detection circuit.

14. The voltage calibration circuit of claim 8 further comprising a voltage setting unit coupled to the coupling voltage detection circuit and the source driving circuit for setting a predetermined shift value for the display voltage.

15. A liquid crystal device (LCD) comprising:

a display module comprising a plurality of parasitic capacitances, a plurality of pixel capacitors and a common voltage terminal, wherein one end of each of the plurality of pixel capacitors is electrically and directly connected to the common voltage terminal;

a gate driving circuit for generating a plurality of gate signals; and

a voltage calibration circuit comprising;

a coupling voltage detection circuit for detecting a coupling voltage in an initial phase and generating a compensation voltage according to the coupling voltage;

a source driving circuit for adjusting a display voltage according to the compensation voltage and outputting the display voltage to the display module in a display phase; and

a switch, having one terminal connected to the common voltage terminal of the display module, and another terminal connected to the coupling voltage detection circuit or a ground terminal, such that the switch is configured to couple the display module to the coupling voltage detection circuit or the ground terminal;

wherein the initial phase is a time period after the display module is turned on but before any image has been displayed;

wherein the coupling voltage in the initial phase is a voltage difference on the common voltage terminal before and after an initial falling edge of gate signals of the display module.