SOURCE DRIVER AND A METHOD OF OPERATING THE SAME

• US 20130307838A1
• Filed: 05/16/2013
• Published: 11/21/2013
• Est. Priority Date: 05/18/2012
• Status: Abandoned Application

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: KIM, Seung-hyun, Lee, Jae-Youn, Lim, Sang-hoon
• Application Number:
  US13/895,475
• Publication Number:
  US 20130307838A1
• Time in Patent Office: Days
• US Class Current: 345/212
• CPC Class Codes: G09G 2310/0235 Field-sequential colour display
• 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 2310/0291 Details of output amplifiers or buffers arranged for use in a driving circuit
• CPC Class Codes: G09G 2310/0297 Special arrangements with multiplexing or demultiplexing of display data in the drivers for data electrodes, in a pre-processing circuitry delivering display data to said drivers or in the matrix panel, e.g. multiplexing plural data signals to one D/A converter or demultiplexing the D/A converter output to multiple columns
• CPC Class Codes: G09G 2340/16 Determination of a pixel data signal depending on the signal applied in the previous frame
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence
• CPC Class Codes: G09G 3/3688 suitable for active matrices only
• CPC Class Codes: G09G 3/3696 Generation of voltages supplied to electrode drivers
• CPC Class Codes: G09G 5/001 Arbitration of resources in a display system, e.g. control of access to frame buffer by video controller and/or main processor

Abstract

A source driver including a first source driving unit including a first source amplifier controlling a first slew rate in response to a first bias control signal and generating a first driving voltage of first display data; a second source driving unit including a second source amplifier controlling a second slew rate in response to a second bias control signal and generating a second driving voltage of second display data; and a bias control signal generating unit sequentially generating the first and second bias control signals, and applying the first and second bias control signals respectively to the first and second source driving units, wherein the first bias control signal is based on a difference between the first display data sequentially applied to the first source amplifier and the second bias control signal is based on a difference between the second display data applied to the second source amplifier.

Claims

1. A source driver for a display device, the source driver comprising:

a first source driving unit comprising a first source amplifier that controls a first slew rate in response to a first bias control signal and generates a first source driving voltage corresponding to first display data;

a second source driving unit comprising a second source amplifier that controls a second slew rate in response to a second bias control signal and generates a second source driving voltage corresponding to second display data; and

a bias control signal generating unit that sequentially generates the first and second bias control signals, and applies the first and second bias control signals respectively to the first and second source driving units,

wherein the first bias control signal is based on a difference between the first display data sequentially applied to the first source amplifier and the second bias control signal is based on a difference between the second display data applied to the second source amplifier.

2. The source driver of claim 1, wherein the first source amplifier adjusts the first slew rate by controlling an amount of a bias current in response to the first bias control signal.

3. The source driver of claim 1, wherein the bias control signal generating unit generates the first bias control signal to increase a bias current of the first source amplifier as the difference between the first display data increases.

4. The source driver of claim 1, further comprising a bias voltage generating unit that applies a bias voltage to the first and second source amplifiers,

wherein bias currents of the first and second source amplifiers are generated in response to the bias voltage, and an amount of the bias current of the first source amplifier is controlled in response to the first bias control signal and an amount of the bias current of the second source amplifier is controlled in response to the second bias control signal.

5. The source driver of claim 1, wherein the first display data comprises current display data and previous display data that is applied to the first source amplifier prior to the current display data,

wherein the bias control signal generating unit comprises:

a line buffer that buffers at least part of the previous display data and outputs the at least part as previous data; and

a comparison unit that generates the first bias control signal based on a difference between the previous data and current data corresponding to at least part of the current display data.

6. The source driver of claim 1, wherein the first source driving unit comprises:

a data latch that receives and stores the first bias control signal and the first display data;

a digital-analog conversion unit that selects a gray-scale voltage corresponding to the first display data from among a plurality of gray-scale voltages; and

the first source amplifier that controls the first slew rate to be adjusted in response to the first bias control signal, and outputs the selected gray-scale voltage as the first source driving voltage.

7. The source driver of claim 1, wherein the first source driving unit sequentially drives a plurality of source lines of a display panel in a time-division manner.

8. The source driver of claim 1, wherein the first display data comprises previous display data and current display data that are sequentially applied to the first source driving unit and each of the previous and current display data comprise first data, second data, and third data sequentially applied to the first source amplifier, and the bias control signal generating unit comprises:

a line buffer that buffers the third data of the previous display data and outputs the third data as previous data;

a first comparator that generates a first sub-bias control signal based on a difference between the previous data and the first data of the current display data;

a second comparator that generates a second sub-bias control signal based on a difference between the first data and the second data of the current display data; and

a third comparator that generates a third sub-bias control signal based on a difference between the second data and the third data of the current display data.

9. The source driver of claim 8, wherein the bias control signal generating unit generates the first, second, and third sub-bias control signals, and outputs the first, second, and third sub-bias control signals as the first bias control signal to the first source driving unit.

10. The source driver of claim 8, wherein the first source driving unit comprises:

a data latch that receives and stores the first, second, and third sub-bias control signals and the current first, second, and third data;

a multiplexer that sequentially selects and outputs the first, second, and third sub-bias control signals in response to a channel selection signal, and sequentially selects and outputs the current first, second, and third data;

a digital-analog conversion unit that selects a gray-scale voltage corresponding to the selected data from among a plurality of gray-scale voltages;

the first source amplifier controls the first slew rate to be adjusted in response to the selected sub-bias control signal, and outputs the selected gray-scale voltage as the first source driving voltage; and

a channel selection unit that sequentially outputs the first source driving voltage through a first channel, a second channel, and a third channel in response to the channel selection signal.

11. A method of operating a source driver comprising a plurality of source amplifiers, the method comprising:

generating a plurality of bias control signals based on a difference between display data sequentially applied to the plurality of the source amplifiers;

respectively controlling slew rates of the plurality of source amplifiers based on the plurality of bias control signals; and

generating source driving voltages using the plurality of source amplifiers.

12. The method of claim 11, wherein the plurality of bias control signals are sequentially generated in a bias control signal generating unit, and each of the plurality of bias control signals is applied to a corresponding one of the plurality of source amplifiers.

13. The method of claim 11, wherein generating the plurality of bias control signals comprises:

generating a first bias control signal of the plurality of bias control signals based on a difference between previous display data output from a line buffer and current display data; and

storing the current display data in the line buffer.

14. The method of claim 11, wherein the display data comprise first data, second data and third data, and each of the plurality of bias control signals comprise first, second and third sub-bias control signals, and

wherein generating a first bias control signal of the plurality of bias control signals comprises:

generating the first sub-bias control signal based on a difference between the third data of previous display data output from a line buffer and the first data of current display data;

generating the second sub-bias control signal based on a difference between the first data and the second data of the current display data;

generating the third sub-bias control signal based on a difference between the second data and the third data of the current display data; and

storing the third data of the current display data in the line buffer.

15. The method of claim 14, wherein a first source amplifier of the plurality of source amplifiers outputs a source driving voltage corresponding to the first data of the current display data when a slew rate of the first source amplifier is adjusted by the first sub-bias control signal, outputs a source driving voltage corresponding to the second data of the current display data when the slew rate of the first source amplifier is adjusted by the second sub-bias control signal, and outputs a source driving voltage corresponding to the third data of the current display data when the slew rate of the first source amplifier is adjusted by the third sub-bias control signal.

16. A source driver, comprising:

a source driving unit configured to output a source driving voltage in response to a bias control signal; and

a bias control signal generating unit configured to generate the bias control signal in response to first display data stored in the bias control signal generating unit and second display data input to the bias control signal generating unit.

17. The source driver of claim 16, wherein a slew rate of the source driving voltage is changed by the bias control signal.

18. The source driver of claim 16, wherein the bias control signal includes first and second sub-bias control signals.

19. The source driver of claim 18, wherein a first bias current corresponding to the first sub-bias control signal is different than a second bias current corresponding to the second sub-bias control signal.

20. The source driver of claim 16, wherein the bias control signal generating unit includes a buffer to store the first display data and a comparator to compare the first display data with the second display data.