Display device

• US 20030179221A1
• Filed: 03/20/2003
• Published: 09/25/2003
• Est. Priority Date: 03/20/2002
• Status: Active Grant

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Hitachi, Ltd.
• Inventors: Tanaka, Yoshinori, Nitta, Hiroyuki, Furuhashi, Tsutomu, Kawabe, Kazuyoshi, Hirakata, Junichi
• Granted Patent: US 7,038,651 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G09G 2310/0205 Simultaneous scanning of several lines in flat panels
• CPC Class Codes: G09G 2310/0224 Details of interlacing
• CPC Class Codes: G09G 2310/0237 Switching ON and OFF the backlight within one frame
• CPC Class Codes: G09G 2310/024 Scrolling of light from the illumination source over the display in combination with the scanning of the display screen
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2310/08 Details of timing specific for flat panels, other than clock recovery
• CPC Class Codes: G09G 2320/02 Improving the quality of display appearance
• CPC Class Codes: G09G 2320/0261 in the context of movement of objects on the screen or movement of the observer relative to the screen
• CPC Class Codes: G09G 2320/10 Special adaptations of display systems for operation with variable images
• CPC Class Codes: G09G 3/3406 Control of illumination source illumination devices structurally associated with liquid crystal cells G02F1/1336
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

In a hold-type display device such as a liquid crystal display device, a so-called blurring which appears on a profile of a displayed animated image or the like can be suppressed without damaging the brightness of the display image. According to the present invention, an image based on video data to be inputted to a display device is displayed for every frame period and, thereafter, the image is masked with a blanking image. Here, a ratio between an image display period of the video data and a blanking image display period in one frame period is adjusted based on the number of selection of pixel rows in a pixel array in response to a scanning clock for respective periods, frequency of the scanning clock, shortening of a horizontal period of display signal inputting to every pixel row with respect to a horizontal scanning period of the video data whereby the display image can be efficiently cancelled using the blanking image while ensuring the image display brightness of the video data.

Claims

1. A display device comprising:

a pixel array having a plurality of pixels which are arranged two-dimensionally along the first direction and the second direction which crosses the first direction;

a plurality of first signal lines which are juxtaposed along the second direction of the pixel array and transmit scanning signals which select a plurality of pixel rows consisting of respective groups formed of a plurality of pixels along the first direction;

a plurality of second signal lines which are juxtaposed along the first direction of the pixel array and supply display signals to the pixels included in pixel rows which are selected from a plurality of pixel rows in response to scanning signals, the display signals determining respective display gray scales of the pixels;

a first driving circuit which outputs the scanning signals to a plurality of respective first signal lines;

a second driving circuit which outputs the display signals to a plurality of respective second signal lines; and

a display control circuit which receives video data and control signals for every frame period, transmits a first clock signal which controls an outputting interval of the scanning signals from the first driving circuit and a scanning starting signal which instructs starting of the pixel row selection step in response to the first clock signal to the first driving circuit, and transmits display data which are served for generating display signals which are generated based on the video data and are outputted from the second driving circuit and a second clock signal which controls an outputting interval of the display signals from the second driving circuit, wherein

the display control circuit makes the first driving circuit perform at least twice the pixel row selection step in the pixel array for every frame period in which the display device receives video data, and

the second driving circuit outputs the display signals in response to the selection of respective pixel rows in the first pixel row selection step which is performed every frame period and outputs display signals which display the pixel array darker than the first selection step to respective selected pixel rows in the second selection step of the pixel row.

2. A display device according to claim 1, wherein the first driving circuit sequentially outputs the scanning signal which selects N lines (N being a natural number of 2 or more) which are arranged close to each other out of the plurality of first signal lines in response to the first clock signal for every N other lines of the plurality of first signal lines.

3. A display device according to claim 1, wherein the second driving circuit outputs the display signal at an interval shorter than a horizontal scanning period of the video data which the display control circuit receives.

4. A display device according to claim 1, wherein the first driving circuit sequentially outputs the scanning signal which selects a plurality of first signal lines every 1 line in response to the first clock signal having frequency which is N times (N being a natural number of 2 or more) larger than frequency of the second clock signal.

5. A display device according to claim 1, wherein the first selection step of the pixel rows during the frame period is allocated a time longer than a time for the second selection step of the pixel rows during the frame period.

6. A display device according to claim 1, wherein the frame period includes a time which is allocated to neither the first selection step nor the second selection step, and the display signal which is supplied to the pixel array in the first selection step which comes before the time or in the second selection step is held in the pixel array during the time.

7. A display device comprising:

a pixel array having a plurality of pixels which are arranged two-dimensionally along the first direction and the second direction which crosses the first direction;

a plurality of first signal lines which are juxtaposed along the second direction of the pixel array and transmit scanning signals which select a plurality of pixel rows consisting of respective groups formed of a plurality of pixel along the first direction;

a plurality of second signal lines which are juxtaposed along the first direction of the pixel array and supply display signals to the pixels included in pixel rows which are selected from a plurality of pixel rows in response to the scanning signals, the display signals determining respective display states of the pixels;

a first driving circuit which outputs the scanning signals to a plurality of respective first signal lines;

a second driving circuit which outputs the display signals to a plurality of respective second signal lines;

a display control circuit which transmits a first clock signal which controls an output interval of the scanning signals to the first signal lines and a scanning starting signal which makes the display control circuit start the selection of the pixel rows over the pixel array in response to the first clock signal to the first driving circuit, and transmits the second clock signal which controls an output interval of the display signals to the second driving circuit; and

a clock generating circuit which generates a display clock signal, wherein

the display control circuit makes the first driving circuit perform, in response to the scanning starting signal, at least twice, steps for selecting the pixel rows over the pixel array for every frame period of the inputted video data, and transfer, in the first pixel row selection step, display data formed based on the video data to the second driving circuit in response to the display clock signal, and

the second driving circuit supplies the first display signal generated based on the display data in the first pixel row selection step to the pixel array in response to the second clock signal, and supplies the second display signal which makes the pixel array darker after supplying of the first display signal to the pixel array in response to the second clock signal in the second pixel row selection step.

8. A display device according to claim 7, wherein the display clock signal has frequency higher than frequency of a dot clock signal included in the video control signals.

9. A display device according to claim 8, wherein the second clock signal has frequency higher than frequency of a horizontal synchronizing signal which is included in the video control signals and inputs the video data to the display control circuit.

10. A display device according to claim 7, wherein the first driving circuit sequentially outputs scanning signals which select N pieces of neighboring lines (N being a natural number of 2 or more) out of the plurality of first signal lines to every N other lines out of the plurality of first signal lines in response to the first clock signal.

11. A display device according to claim 7, wherein the second driving circuit outputs the display signal at an interval shorter than a horizontal scanning period of the video data which the display control circuit receives.

12. A display device according to claim 7, wherein the first driving circuit sequentially outputs the scanning signal which selects a plurality of first signal lines every 1 line in response to the first clock signal having frequency which is N times (N being a natural number of 2 or more) larger than frequency of the second clock signal.

13. A display device according to claim 7, wherein the scanning starting signal includes a first pulse and a second pulse which respectively correspond to the first and second pixel row selection steps for every frame period, and an interval between the first pulse and the second pulse of the scanning starting signal which is generated in a certain frame period differs from an interval between the second pulse and a first pulse of the scanning starting signal which is generated in a frame period next to the certain frame period.

14. A display device comprising:

a liquid crystal panel having a plurality of pixels which are arranged two-dimensionally along the first direction and the second direction which crosses the first direction;

a plurality of first signal lines which are juxtaposed along the second direction of the liquid crystal panel and transmit scanning signals which select a plurality of pixel rows consisting of respective groups formed of a plurality of pixel along the first direction;

a plurality of second signal lines which are juxtaposed along the first direction of the liquid crystal panel and supply display signals to the pixels included in pixel rows which are selected from a plurality of pixel rows in response to scanning signals, the display signals determining respective display gray scales of the pixels;

a first driving circuit which outputs the scanning signals to a plurality of respective first signal lines;

a second driving circuit which outputs the display signals to a plurality of respective second signal lines;

a lighting device which irradiates light to the liquid crystal panel; and

a display control circuit which receives video data and control signals thereof for every frame period, transmits a first clock signal which controls an output interval of the scanning signals and a scanning starting signal which instructs starting of the pixel row selection step in response to the first clock signal to the first driving circuit, and transmits display data which are formed based on the video data and are served for outputting of display signals by the second driving circuit and a second clock signal which controls an output interval of the display signals to the second driving circuit,

the display control circuit makes the first driving circuit perform the pixel row selection step at least twice for every frame period in which the video data are received, and

the second driving circuit outputs the display signal generated based on the display data in the first pixel row selection step performed for every frame period in response to the selection of respective pixel rows, and outputs th display signals which make optical transmissivity of the liquid crystal panel in the second pixel row selection step lower than the optical transmissivity of the liquid crystal panel in the first pixel row selection step, and

the lighting device is controlled to start lighting thereof during the first pixel row selection step for every frame period and to stop lighting during the second pixel row selection step for every frame period.

15. A display device according to claim 14, wherein timing of starting and finishing of the lighting operation for every frame period of the lighting device is determined by a lighting control signal which is generated in synchronism with the first clock signal by the display control circuit.

16. A method for driving a display device which includes a pixel array in which a plurality of pixel rows each including a plurality of pixel juxtaposed in the first direction are juxtaposed in the second direction which crosses the first direction and a display control circuit which controls the display operation of the pixel array, the method comprising:

a step for intermittently inputting the display data to the display device for every frame period; and

a step for respectively outputting a scanning clock signal which determines an inputting interval of scanning signals for respectively selecting a plurality of pixel rows for every frame period to the pixel array, a scanning starting signal which starts an operation to select the pixel rows over the pixel array in response to the scanning clock signal, and a timing signal which determines an interval for supplying display signals which determines display states to the pixel rows or a group of pixels selected by the scanning signals, wherein

the scanning starting signal includes a first scanning starting signal which is outputted in response to inputting of the video data to the display device every frame period and a second scanning starting signal which is outputted after the inputting of the video data to the display device is finished,

the display signal includes a first display signal which is inputted to the pixel array in response to the first scanning starting signal and a second display signal which is inputted to the pixel array in response to the second scanning signal voltage,

the first display signal is generated in the inside of the display device based on the video data, and

the second display signal is also generated in the inside of the display device as a signal which makes the display brightness of the pixel array darker than the display brightness of the pixel array after the first display signal is supplied to the pixel array.

17. A method for driving a display device according to claim 16, wherein the number of the pixel rows selected by respective scanning signals during the period in which the second display signal is inputted to the pixel array may be set larger than the number of the pixel rows selected by respective scanning signals during the period in which the first display signal is inputted to the pixel array.

18. A method for driving a display device according to claim 16, wherein the frequency of the scanning clock signal during the period in which the second display signal is inputted to the pixel array may be set higher than the frequency of the scanning clock signal during the period in which the first display signal is inputted to the pixel array.

19. A method for driving a display device according to claim 16, wherein the frequency of the scanning clock signal may be set higher than the frequency of the timing signal.