Display apparatus and method of driving the same

• US 9,318,063 B2
• Filed: 08/22/2012
• Issued: 04/19/2016
• Est. Priority Date: 02/17/2012
• Status: Expired due to Fees

• Current Assignee: Samsung Display Company Limited (Samsung Group)
• Original Assignee: Samsung Display Company Limited (Samsung Group)
• Inventors: Kim, Tae-Jin
• Primary Examiner(s): Patel, Kumar
• Assistant Examiner(s): Ahn, Sejoon
• Application Number:
  US13/591,531
• Publication Number:
  US 20130215096A1
• Time in Patent Office: 1,336 Days
• Field of Search: 345 87-104, 345204-699
• US Class Current: 1/1
• CPC Class Codes: G09G 2320/0214 with crosstalk due to leakage current of pixel switch in active matrix panels
• CPC Class Codes: G09G 2320/103 Detection of image changes, e.g. determination of an index representative of the image change
• CPC Class Codes: G09G 2330/021 Power management, e.g. power saving
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3655 Details of drivers for counter electrodes, e.g. common electrodes for pixel capacitors or supplementary storage capacitors

Abstract

A method of driving a display apparatus including a plurality of pixels that respectively store a voltage level corresponding to a data signal and respectively include a storage capacitor connected between a pixel electrode and a second common voltage electrode, the method including operations of determining whether image data of a current frame is changed, compared to image data of a previous frame, when the image data of the current frame is changed, storing a voltage level corresponding to the image data of the current frame in the storage capacitor of each of the plurality of pixels, and when the image data of the current frame is not changed, changing a level of a second common voltage applied to the second common voltage electrode of each of the plurality of pixels.

Claims

1. A method of driving a display apparatus having a plurality of pixels, each pixel including a liquid crystal cell connected between a pixel electrode and a first common voltage electrode and a storage capacitor connected between the pixel electrode and a second common voltage electrode, the method comprising:

determining whether image data of a current frame is changed, as compared to image data of a previous frame;

when the image data of the current frame is changed, storing a voltage level corresponding to the image data of the current frame in the storage capacitor of each of the plurality of pixels;

when the image data of the current frame is not changed, changing a level of a second common voltage applied to the second common voltage electrode of each of the plurality of pixels; and

when a reference time elapses after the voltage level is changed to the level of the second common voltage applied to the second common voltage electrode of each of the plurality of pixels, changing the level of the second common voltage to a level before the second common voltage is changed.

2. The method of claim 1, wherein, when the image data of the current frame is not changed, the image data of the current frame is not written to the pixel electrode of each of the plurality of pixels.

3. The method of claim 1, wherein changing the level of the second common voltage is performed to compensate for a voltage drop of the pixel electrode of each of the plurality of pixels.

4. The method of claim 1, further comprising

measuring a voltage level of the pixel electrode of each of the plurality of pixels, and

when a difference between the voltage level of the pixel electrode and the voltage level corresponding to the image data of the current frame is equal to or greater than a reference value, changing the level of the second common voltage includes compensating for a voltage drop of the pixel electrode by changing the level of the second common voltage by the difference.

5. The method of claim 1, wherein changing the level of the second common voltage includes changing the level of the second common voltage by a set voltage value at regular intervals.

6. The method of claim 1, wherein the display apparatus is an electrophoretic image display apparatus, an organic electroluminescent display apparatus, or a liquid crystal display apparatus.

15. The method of claim 1, further comprising,

when the image data of the current frame is changed, inverting a polarity of a voltage applied to a liquid crystal cell.

7. A display apparatus, comprising:

a pixel unit including a plurality of pixels, each of the plurality of pixels including a liquid crystal cell connected between a pixel electrode and a first common voltage electrode and a storage capacitor connected between the pixel electrode and a second common voltage electrode;

a common voltage driver to supply a second common voltage to the plurality of pixels; and

a compensation controller to determine whether image data of a current frame is changed, as compared to image data of a previous frame,

wherein, when the image data of the current frame is changed, the compensation controller is to control the common voltage driver to store a voltage level corresponding to the image data of the current frame in the storage capacitor of each of the plurality of pixels,

wherein, when the image data of the current frame is not changed, the compensation controller is to control the common voltage driver to change a level of the second common voltage applied to the second common voltage electrode of each of the plurality of pixels, and

wherein, when a reference time elapses after the voltage level is changed to the level of the second common voltage applied to the second common voltage electrode of each of the plurality of pixels, the compensation controller is to control the common voltage driver to change the level of the second common voltage to a level before the second common voltage is changed.

8. The display apparatus of claim 7, wherein, when the image data of the current frame is not changed, the compensation controller is to control the image data of the current frame not to be written to the pixel electrode of each of the plurality of pixels.

9. The display apparatus of claim 7, wherein, when the image data of the current frame is not changed, the compensation controller is to control the level of the second common voltage to be changed to compensate for a voltage drop of the pixel electrode of each of the plurality of pixels.

10. The display apparatus of claim 7, wherein each of the plurality of pixels further comprises a first transistor having a gate electrode connected to a gate line for delivering a scan signal, a first electrode connected to a data line for delivering a data signal, and a second electrode connected to the pixel electrode.

11. The display apparatus of claim 7, further comprising:

a voltage detector to measure a voltage level of the pixel electrode of each of the plurality of pixels, and

when a difference between the voltage level of the pixel electrode and the voltage level corresponding to the image data of the current frame is equal to or greater than a reference value, the compensation controller is to control a voltage drop of the pixel electrode to be compensated for by changing the level of the second common voltage by the difference.

12. The display apparatus of claim 7, wherein, when the level of the second common voltage is changed, the compensation controller is to control the level of the second common voltage to be changed by a set voltage value at regular intervals.

13. The display apparatus of claim 7, wherein the display apparatus is an electrophoretic image display apparatus, an organic electroluminescent display apparatus, or a liquid crystal display apparatus.

14. The display apparatus of claim 7, further comprising:

a scan driver to output a scan signal to each of the plurality of pixels;

a data driver to output a data signal to each of the plurality of pixels; and

a timing controller to control the scan driver and the data driver.

16. The display apparatus of claim 7, wherein, when the image data of the current frame is changed, the compensation controller is to control a polarity of a voltage to be inverted, wherein the voltage is applied to the liquid crystal cell.