Device and method for controlling luminance of flat display

• US 6,661,428 B1
• Filed: 04/14/2000
• Issued: 12/09/2003
• Est. Priority Date: 04/15/1999
• Status: Expired due to Term

• Current Assignee: LG Electronics, Inc. (LG Corporation)
• Original Assignee: LG Electronics, Inc. (LG Corporation)
• Inventors: Kim, Hak Su
• Primary Examiner(s): Hjerpe, Richard
• Assistant Examiner(s): Eisen, Alexander
• Application Number:
  US09/550,071
• Time in Patent Office: 1,334 Days
• Field of Search: 345/55, 345/59, 345/77, 345/89, 345/99, 345/204, 345/211, 345/213, 345/690-693, 315/169--16
• US Class Current: 345/690
• CPC Class Codes: G09G 2310/02 Addressing, scanning or driving the display screen or processing steps related thereto
• CPC Class Codes: G09G 3/20 for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
• CPC Class Codes: G09G 3/2014 by modulation of the duration of a single pulse during which the logic level remains constant
• CPC Class Codes: G09G 3/2018 by time modulation using two or more time intervals
• CPC Class Codes: G09G 5/30 Control of display attribute

Abstract

Device and method for controlling a luminance of a flat display minimizes a chip area, and controls a luminance of a desired portion of a display efficiently without an additional power consumption. The device includes a reference signal part for receiving an external video signal and provides a duty ratio of a scan signal and a video data desired to display. A controller converts the duty ratio from the reference signal part and generates a remaining scan time period. A display part receives and displays an image data (video data) with the application of scanning pulses having a duty ratio processed by the controller.

Claims

1. A driving circuit for a display device, comprising:

a reference signal generator that receives video signal, said reference signal generator generating a first duty ratio and a video data;

a controller receiving the first duty ratio and video data, said controller converting the first duty ratio to a second duty ratio when a luminance of a pixel of the display device is to be changed, said second duty ratio being less than the first duty ratio;

a driver circuit that used the second duty ratio and video data for displaying at least one of image and text, wherein the controller includes a scan controller circuit for converting the first duty ratio to the second duty ratio thereby changing a first scan time period to a second time period within which a scan line is driven for one frame period such that there is an additional scan time period for driving a plurality of scan lines, and the scan controller applying the additional scan time period to a scan line desired to display brighter than other scan lines.

2. The circuit of claim 1, wherein the controller includes:

a frequency converter that generates a plurality of second clock signals based on a first clock signal;

a frequency selector for selecting one of the plurality of second clock signals as a reference clock signal;

a duty ratio controller for setting up the second duty ratio based on the reference clock signal;

a first signal controller for generating a first signal for driving a first signal line based on the second duty ratio; and

a display controller for synchronizing the duty ratio controller and the first signal controller.

3. The circuit of claim 2, wherein said first signal controller is a scan signal controller and the first signal line is a scan line.

4. The device of claim 3, wherein the controller further includes a data signal controller for converting a data by using masking in applying an additional scan time period remaining based on the second duty ratio to a particular scan line.

5. The circuit of claim 1, wherein the reference signal generator includes:

a system interface for receiving a video signal and converting the video signal to a control signal and video data for display;

a control circuit for fixing the first duty ratio in response to the control signal; and

a memory for storage of the video data.

6. The circuit of claim 1, wherein the controller further includes a data controller for driving a portion or entire data corresponding to the scan lines applied and masking the rest of the data.

7. The circuit of claim 1, wherein the additional scan time period is applied to a single scan line.

8. The circuit of claim 1, wherein the additional scan time period is divided into a plurality of additional scan time periods, each being applied to a corresponding scan line for brighter luminance or the plurality of additional scan time periods being to a prescribed number of the plurality of scan lines, respectively.

9. The circuit of claim 1, wherein the plurality of additional scan time periods is adjusted through masking.

10. The circuit of claim 1, wherein the driver circuit includes:

a data driver for applying video data from the controller to a plurality of data lines; and

a scan driver for applying a driving signal based on the second duty ratio from the controller to a plurality of scan lines, for displaying at least one of image and text.

11. The driving circuit of claim 1, wherein the additional scan time period includes a number N of additional scan signals, where 1≦

N<

the number of scan lines.

12. A controller for a display device comprising:

a scan controller circuit for converting a first duty ratio based on a first scan time period for each of a plurality of scan lines to a second duty ratio based on a second scan time period within which each scan line is driven for one frame period; and

a data controller circuit for driving a portion or entire data corresponding to the scan lines, wherein the second duty ratio is less than the first duty ratio such that there are additional second scan time period remaining for driving the plurality of scan lines within one frame period, wherein the additional second scan time period is used in at least one of the following;

(a) the additional second scan time period is applied to a single scan line,

(b) the additional second scan time period is divided into a plurality of additional scan time periods, each being applied to a corresponding scan line for brighter luminance or the plurality of additional scan time periods being applied to a prescribed number of the plurality of scan lines, respectively, and

(c) the additional second scan time period is adjusted through masking.

13. The controller of claim 12, wherein the data controller circuit converts a data by using masking in applying the additional second scan time period to a corresponding scan line.

14. The controller of claim 12, wherein the additional scan time period includes a number N of additional scan signals, where 1≦

N<

the number of scan lines.

15. A display device, comprising:

a input device receiving a video signal and generating a first duty ratio and video data;

a controller that changes the first duty ratio to a second duty ratio; and

a display panel having a plurality of scan lines and a plurality of data lines intersecting at a plurality of pixels, said plurality of scan lines being driven based on the second duty ratio and video data being provided to the plurality of data lines to display at least one of an image and text, wherein

the controller includes a scan controller circuit for converting the first duty, ratio to the second duty ratio thereby changing a first scan time period to a second time period within which a scan line is driven for one frame period such that there is an additional scan time period for driving a plurality of scan lines, and the scan controller applying the additional scan time period to a scan line desired to display brighter than other scan lines.

16. The display devise of claim 15, wherein the additional scan time period includes a number N of additional scan signals, where 1≦

N<

the number of scan lines.

17. A method for controlling a luminance of a flat display, comprising:

(1) while a frame frequency is maintained, adjusting a duty ratio of a scan time period for generating additional scan time period; and

(2) adding the additional scan time period to all scan lines desired to be displayed brighter than other scan lines, wherein the additional second scan time period is used in at least one of the following;

(a) the additional second scan time period is applied to a single scan line,

(b) the additional second scan time period is divided into a plurality of additional scan time periods, each being applied to a corresponding scan line for brighter luminance or the plurality of additional scan time periods being applied to a prescribed number of the plurality of scan lines, respectively, and

(c) the additional second scan time period is adjusted through masking.

18. The method of claim 17, wherein the step (2) further includes the step of displaying only driving data on a plurality of data lines desired to display brighter while the driving data on rest of the data line are masked, for selectively driving the data lines.

19. The method of claim 18, wherein the step of driving the data lines further includes the step of adjusting the driving time period through partial masking of the data on a particular data line desired to display brighter for adjusting a luminance of the data.

20. The method of claim 17, wherein step (2) includes the steps of:

driving the scan lines starting from beginning in succession by using the adjusted duty ratio; and

adding a portion or entire additional scan time period to the scan lines desired to display brighter than other scan lines, and driving the scan lines.

21. The method of claim 17, wherein step (2) includes the steps of:

selectively applying a portion or entire additional scan time period to the scan lines desired to display brighter than other scan lines; and

applying a fixed time period to all the scan lines in succession using the adjusted duty ratio.

22. The method of claim 17, wherein step (2) includes the steps of:

partially masking a data on a particular scan line desired to display brighter than other scan lines, to adjust a driving time period therefor, for adjusting a luminance of the data.

23. The method of claim 17, wherein the additional scan time period includes a number N of additional scan signals, where 1≦

N<

the number of scan lines.

24. The method of claim 17, where the duty ratio is adjusted to a lesser duty ratio.

25. A driving circuit of a display panel comprising:

a scan electrode driving part for sequentially applying scan signals to each scan electrode, so as to drive a display panel of a passive matrix type including a plurality of pixels defined by crossing a plurality of scan electrode lines to a plurality data electrode lines;

a data electrode driving part for applying a data signal to a data electrode; and

a control part for controlling each driving part,

wherein the control part generate the scan signals greater than a number of the scan electrode lines so as to provide additional scan signals, and the scan electrode driving part is controlled apply the additional scan signals to scan electrode lines desired to be brighter than the others.

26. The driving circuit of claim 25, wherein the number of the additional scan signals N is 1≦

N<

the number of scan lines.

27. The driving circuit of claim 25, wherein the additional scan signal are used when a brighter luminescence is desired for a prescribed number of pixels.

28. The driving circuit of claim 25, wherein the scan electrode driving part switches the applied additional scan signal.

29. The driving circuit of claim 25, herein the data electrode driving part is controlled to mask the data signal.

30. The driving circuit of a display panel comprising:

a scan electrode driving part for sequentially applying scan signals to each scan electrode, so as to drive a display panel of a passive matrix type including a plurality of pixels defined by crossing a plurality of scan electrode lines to a plurality data electrode lines;

a data electrode driving part for applying a data signal to a data electrode; and

a control part for controlling each driving part,

wherein the control part generate the scan signals greater than a number of the scan electrode lines so as to provide additional scan signals, and the scan electrode driving part is controlled to apply the additional scan signals to scan electrode lines desired to be brighter than the others, and the data driving part is controlled to mask data signals on rest of the data lines except for data lines desired to display brighter than the others.

31. The driving circuit of claim 30, wherein the number of the additional scan signals N is 1≦

N<

the number of scan lines.

32. The driving circuit of claim 30, wherein the additional scan signal are used when a brighter luminescence is desired for a prescribed number of pixels.

33. The driving circuit of claim 30, wherein the scan electrode driving part switches the applied additional scan signal.