LCD driving apparatus capable of self-adjusting drive force and method thereof

• US 8,421,730 B2
• Filed: 01/25/2008
• Issued: 04/16/2013
• Est. Priority Date: 07/16/2007
• Status: Active Grant

• Current Assignee: MediaTek, Inc.
• Original Assignee: MStar Semiconductor Incorporated (MediaTek, Inc.)
• Inventors: Wang, Chien Chuan
• Primary Examiner(s): Nguyen, Chanh
• Assistant Examiner(s): NOKHAM, JAMES S
• Application Number:
  US12/010,451
• Publication Number:
  US 20090021498A1
• Time in Patent Office: 1,908 Days
• Field of Search: 345/87, 345/92, 345/100, 345/204, 345/84, 345/104, 345/211, 345/98
• US Class Current: 345/98
• CPC Class Codes: G09G 2320/0223 Compensation for problems related to R-C delay and attenuation in electrodes of matrix panels, e.g. in gate electrodes or on-substrate video signal electrodes
• CPC Class Codes: G09G 2320/0693 Calibration of display systems
• CPC Class Codes: G09G 2330/02 Details of power systems and of start or stop of display operation
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

The invention provides an LCD driving apparatus which can self-adjust its drive force for different LCD panels. The LCD driving apparatus comprising: a variable resistor coupled to a data line of an LCD panel for receiving an input voltage, and then outputting an output current to the data line of said LCD panel; a comparison unit coupled to the data line of the LCD panel for receiving a voltage of a display unit of the data line, and comparing the voltage with a predetermined voltage for generating a comparing result; and an adjustment unit for adjusting the variable resistor in accordance with the comparing result for changing the value of the output current.

Claims

1. An LCD driving apparatus capable of self-adjusting drive force comprising:

a variable resistor including a first terminal capable of receiving an input voltage and a second terminal directly connected to a data line of an LCD panel for outputting an output current to said data line of said LCD panel;

a comparison unit including a first input terminal directly connected to said second terminal of said variable resistor for receiving a charged voltage of a display unit at said data line, and including a second input terminal directly connected to a predetermined voltage, and including an output terminal without connecting to said variable resistor, wherein said comparison unit is capable of comparing said charged voltage with a predetermined voltage for generating a comparing result at said output terminal of said comparison unit; and

an adjustment unit connected to said output terminal of said comparison unit, for adjusting said variable resistor to change the value of said output current according to said comparing result, wherein when said charged voltage is smaller than said predetermined voltage, said resistance of said variable resistor is lowered for making said output current larger; and

when said charged voltage is larger than said predetermined voltage, said resistance of said variable resistor is enlarged for making said output current lower.

2. The LCD driving apparatus of claim 1, wherein said charged voltage of said display unit is the voltage stored in a liquid crystal capacitor and a storage capacitor of said display unit after charged by said output current.

3. The LCD driving apparatus of claim 1, wherein when a scan voltage is inputted to a plurality of scan lines of said LCD panel in sequence, a plurality of display units at said data line are charged in sequence by said output current, said comparison unit performs a comparison once for generating said comparing result whenever one of the plurality of display units is charged, and said adjustment unit adjusts said variable resistor once according to said comparing result.

4. The LCD driving apparatus of claim 1, wherein said comparison unit comprises a sense amplifier.

5. The LCD driving device of claim 1, wherein said comparison unit and said adjustment unit are executed only at the first frame on said LCD panel after power on.

6. An LCD driving method capable of self-adjusting drive force, comprising the steps of:

providing an input voltage to a first terminal of a variable resistor and then generating an output current issued from a second terminal of said variable resistor to a data line of an LCD panel for charging a display unit at said data line;

comparing a charged voltage of said second terminal of said variable resistor with a predetermined voltage by using a comparison unit for generating a comparing result at an output terminal of said comparison unit, wherein said comparison unit includes a first input terminal directly connected to said second terminal of said variable resistor for receiving said charged voltage of said display unit at said data line, and includes a second input terminal directly connected to said predetermined voltage, and includes said output terminal without connecting to said variable resistor; and

adjusting said variable resistor to change the value of said output current according to said comparing result, wherein when said charged voltage is smaller than said predetermined voltage, said resistance of said variable resistor is lowered for making said output current larger; and

when said charged voltage is larger than said predetermined voltage, said resistance of said variable resistor is enlarged for making said output current lower.

7. The LCD driving method of claim 6, wherein when a scan voltage is inputted to a plurality of scan lines of said LCD panel in sequence, execute three steps of said LCD driving method once whenever said scan voltage is inputted to one of said plurality of scan lines.

8. The LCD driving method of claim 6, wherein said LCD driving method is applied only at the first frame on said LCD panel after power on.

9. The LCD driving method of claim 6, wherein said charged voltage of said display unit is the voltage stored in a liquid crystal capacitor and a storage capacitor of said display unit after charged by said output current.