LIQUID CRYSTAL DISPLAY DEVICE CAPABLE OF REDUCING RESIDUAL IMAGES AND RELATED METHOD THEREOF

• US 20130342434A1
• Filed: 09/09/2012
• Published: 12/26/2013
• Est. Priority Date: 06/26/2012
• Status: Abandoned Application

• Current Assignee: AmTRAN Technology Co., Ltd.
• Original Assignee: AmTRAN Technology Co., Ltd.
• Inventors: Chen, Chien-Chou, Huang, Yu-Nan
• Application Number:
  US13/607,782
• Publication Number:
  US 20130342434A1
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G09G 2310/0237 Switching ON and OFF the backlight within one frame
• CPC Class Codes: G09G 2320/0247 Flicker reduction other than flicker reduction circuits used for single beam cathode-ray tubes
• CPC Class Codes: G09G 2320/0257 Reduction of after-image effects
• CPC Class Codes: G09G 3/342 using several illumination sources separately controlled corresponding to different display panel areas, e.g. along one dimension such as lines

Abstract

A method of reducing residual images of a liquid crystal display device includes generating multiple pulse width modulation signals corresponding to display blocks of a liquid crystal panel in turn; generating multiple driving signals corresponding to the display blocks according to the pulse width modulation signals; and correspondingly providing backlight to the display blocks according to the driving signals. During each frame period of the liquid crystal panel, each pulse width modulation signal has a first fixed width pulse voltage and a second fixed width pulse voltage. A period between a beginning of the first fixed width pulse voltage and an end of the second fixed width pulse voltage is longer than or equal to 16 milliseconds minus a predetermined time. A period between the end and a beginning of a first fixed width pulse voltage of a next frame period is shorter than or equal to the predetermined time.

Claims

1. A liquid crystal display device capable of reducing residual images, the liquid crystal display device comprising:

a liquid crystal panel having a 60 Hz frame rate, wherein the liquid crystal panel comprises multiple display blocks;

a pulse width modulation signal generator for generating multiple pulse width modulation signals corresponding to the display blocks in turn, wherein each pulse width modulation signal has a first fixed width pulse voltage and a second fixed width pulse voltage during each frame period of the liquid crystal panel, a period between a beginning of the first fixed width pulse voltage and an end of the second fixed width pulse voltage is longer than or equal to 16 milliseconds minus a predetermined time, wherein a period between the end of the second fixed width pulse voltage and a beginning of a first fixed width pulse voltage of a next frame period is shorter than or equal to the predetermined time;

a backlight driving circuit for generating multiple driving signals corresponding to the display blocks according to the pulse width modulation signals; and

a backlight module for correspondingly providing backlight to the display blocks according to the driving signals.

2. The liquid crystal display device of claim 1, wherein each pulse width modulation signal further has an adjustable width pulse voltage during each frame period of the liquid crystal panel, the adjustable width pulse voltage exists between the first fixed width pulse voltage and the second fixed width pulse voltage, and the adjustable width pulse voltage is followed behind the first fixed width pulse voltage, or the second fixed width pulse voltage is followed behind the adjustable width pulse voltage.

3. The liquid crystal display device of claim 2, wherein a sum of a lasting time of the first fixed width pulse voltage, a lasting time of the second fixed width pulse voltage and a lasting time of the adjustable width pulse voltage is shorter than or equal to the period between the beginning of the first fixed width pulse voltage and the end of the second fixed width pulse voltage.

4. The liquid crystal display device of claim 2, wherein the period between the beginning of the first fixed width pulse voltage and the end of the second fixed width pulse voltage is equal to a sum of a lasting time of the first fixed width pulse voltage, a lasting time of the second fixed width pulse voltage and a lasting time of the adjustable width pulse voltage.

5. The liquid crystal display device of claim 4, wherein the period between the beginning of the first fixed width pulse voltage and the end of the second fixed width pulse voltage is defined as a liquid crystal relative steady-state area of the liquid crystal panel.

6. A method of reducing residual images of a liquid crystal display device, the liquid crystal display device comprising a pulse width modulation signal generator, a backlight driving circuit, a backlight module, and a liquid crystal panel, wherein the liquid crystal panel has a 60 Hz frame rate, and the liquid crystal panel comprises multiple display blocks, the method comprising:

the pulse width modulation signal generator generating multiple pulse width modulation signals corresponding to the multiple display blocks in turn, wherein each pulse width modulation signal has a first fixed width pulse voltage and a second fixed width pulse voltage during each frame period of the liquid crystal panel, a period between a beginning of the first fixed width pulse voltage and an end of the second fixed width pulse voltage is longer than or equal to 16 milliseconds minus a predetermined time, wherein a period between the end of the second fixed width pulse voltage and a beginning of a first fixed width pulse voltage of a next frame period is shorter than or equal to the predetermined time;

the backlight driving circuit generating multiple driving signals corresponding to the display blocks according to the pulse width modulation signals; and

the backlight module correspondingly providing backlight to the display blocks according to the driving signals.

7. The method of claim 6, wherein each pulse width modulation signal further has an adjustable width pulse voltage during each frame period of the liquid crystal panel, the adjustable width pulse voltage exists between the first fixed width pulse voltage and the second fixed width pulse voltage, and the adjustable width pulse voltage is followed behind the first fixed width pulse voltage, or the second fixed width pulse voltage is followed behind the adjustable width pulse voltage.

8. The method of claim 7, wherein a sum of a lasting time of the first fixed width pulse voltage, a lasting time of the second fixed width pulse voltage and a lasting time of the adjustable width pulse voltage is shorter than or equal to the period between the beginning of the first fixed width pulse voltage and the end of the second fixed width pulse voltage.

9. The method of claim 7, wherein the period between the beginning of the first fixed width pulse voltage and the end of the second fixed width pulse voltage is equal to a sum of a lasting time of the first fixed width pulse voltage, a lasting time of the second fixed width pulse voltage and a lasting time of the adjustable width pulse voltage.

10. The method of claim 9, wherein the period between the beginning of the first fixed width pulse voltage and the end of the second fixed width pulse voltage is defined as a liquid crystal relative steady-state area of the liquid crystal panel.