Liquid crystal display device, source driver, and method of driving a liquid crystal display panel

• US 8,063,896 B2
• Filed: 01/30/2008
• Issued: 11/22/2011
• Est. Priority Date: 01/31/2007
• Status: Active Grant

• Current Assignee: Renesas Electronics Corporation
• Original Assignee: Renesas Electronics Corporation
• Inventors: Nishimura, Kouichi
• Primary Examiner(s): Xiao, Ke
• Assistant Examiner(s): HERNANDEZ, JESUS J
• Application Number:
  US12/010,840
• Publication Number:
  US 20080180427A1
• Time in Patent Office: 1,392 Days
• Field of Search: None
• US Class Current: 345/209
• CPC Class Codes: G09G 2310/027 Details of drivers for data electrodes, the drivers handling digital grey scale data, e.g. use of D/A converters
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 3/3688 suitable for active matrices only

Abstract

A source driver which can control the spatial cycle of inverting the polarity of offset voltage in response to the spatial cycle of inverting the polarity of data signal. The liquid crystal display device according to the present invention has an LCD panel, having data lines, and source drivers for supplying data signal to the data lines. The source driver includes an offset cancel control circuit for generating an offset cancel control signal and an amplifier used for generating the data signal, which is configured so as to invert the polarity of the offset voltage in response to the offset cancel control signal OCC. The offset cancel controller circuit receives the pattern select signal PSEL specifying the cycle of inverting the polarity of the offset voltage of the amplifier to generate the offset cancel control signal in response to the pattern select signal PSEL.

Claims

1. A display device, comprising:

a display panel having a data line; and

a source driver coupled to said panel, said source driver including a control circuit and an amplifier, said amplifier being coupled to said data line to supply a data signal with an offset voltage, said amplifier being responsive to a control signal from said control circuit to invert a polarity of said offset voltage,

wherein said control circuit generates said control signal in response to a pattern select signal, a gate start pulse signal, and a strobe signal indicative of a cycle of inversion of the polarity of said offset voltage,

wherein the source driver is configured to drive said display panel in a 2H inverted drive,

wherein said polarity of said offset voltage of said amplifier during said 2H inverted drive is inverted for every one horizontal line in response to said pattern select signal,

wherein the display device further comprises a gate driver for scanning gate lines in the display panel,

wherein the gate start pulse signal is supplied to the gate driver for initiating the scan by the gate driver,

wherein the source driver comprises;

a plurality of registers sequentially receiving display data from an external source;

a plurality of latches responsive to the strobe signal to latch the display data from the registers simultaneously; and

a driver circuit for driving the data lines in response to the display data latched in the latch circuits, and

wherein the control circuit comprises;

a first divider circuit dividing the gate start pulse signal to generate ¼

divided gate start pulse signal;

a second divider circuit dividing the strobe signal to generate ¼

divided strobe signal and ½

divided strobe signal;

a first selector circuit in response to the pattern select signal to select either the ¼

divided strobe signal or the ½

divided strobe signal; and

a second selector circuit in response to an output of the first selector circuit for outputting the ¼

divided gate start pulse signal or the inverted signal of the ¼

divided gate start pulse signal.

2. The display device according to claim 1, wherein the source driver is configured to drive said display panel in a 1H inverted drive and in said 2H inverted drive alternatively, and

wherein said polarity of said offset voltage of said amplifier during the 1H inverted drive is inverted for every two horizontal lines in response to said pattern select signal.

3. The display device according to claim 1, wherein the source driver further includes a D/A converter supplied with a set of grayscale voltages to select and output one thereof based on display data, and

wherein the amplifier includes a power amplifier coupled to receive the one grayscale voltage from the D/A converter to generate the data signal in response to the one grayscale voltage.

4. The display device according to claim 1, wherein the source driver further includes:

a grayscale voltage generator circuit;

a D/A converter supplied with a set of grayscale voltages from said generator circuit to select and output one thereof based on display data; and

a power amplifier responsive to the selected grayscale voltage to generate the data signal, and

wherein the amplifier includes a gamma amplifier integrated with the grayscale voltage generator circuit to cooperate to generate the set of grayscale voltages.

5. The display device according to claim 1, wherein the source driver further includes:

a grayscale voltage generator circuit; and

a D/A converter supplied with a set of grayscale voltages from said generator circuit to select and output one thereof based on display data, and

wherein the amplifier includes;

a power amplifier to generate the data signal based on the selected grayscale voltage; and

a gamma amplifier integrated with the grayscale voltage generator circuit to generate the set of grayscale voltages.

6. The display device according to claim 1, wherein data indicative of the pattern select signal or a value of the pattern select signal is externally supplied to the source driver.

7. The display device according to claim 1, wherein a polarity signal is supplied to the source driver to specify a polarity of the data signal, and

wherein the source driver includes a determining circuit responsive to said polarity signal to determine the cycle of inversion of the polarity of the data signal and to generate the pattern select signal in response to a result of the determination.

8. The display device according to claim 1, wherein said control circuit generates said control signal further in response to an offset cancel enable signal, said offset cancel enable signal comprising a signal that forbids a control on said inverting the polarity of the offset voltage.

9. The display device according to claim 8, wherein, when the offset cancel enable signal is at a first level, the control of the inverting the polarity of the offset voltage is allowed, and

wherein, when the offset cancel enable signal is at a second level, said control signal is fixed such that the polarity of the offset voltage is not inverted.

10. The display device according to claim 1, wherein the gate start pulse signal inverts said control signal for a predetermined number of frame intervals, and

wherein an activation of the gate start pulse signal indicates a start of each of said frame intervals.

11. The display device according to claim 10, wherein the strobe signal indicates a start of a horizontal period, the strobe signal inverting said control signal for a desired number of horizontal periods for said inverting the polarity of said offset voltage.

12. The display device according to claim 1, wherein the pattern select signal comprises a signal that specifies the cycle of inversion of the polarity of the offset voltage.