Method and apparatus for correcting the output signal for a blanking period

• US 7,903,064 B2
• Filed: 09/14/2005
• Issued: 03/08/2011
• Est. Priority Date: 09/17/2004
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Shiomi, Makoto
• Primary Examiner(s): Mengistu; Amare
• Assistant Examiner(s): Lee; Gene W
• Application Number:
  US11/663,079
• Publication Number:
  US 20070252795A1
• Time in Patent Office: 2,001 Days
• Field of Search: 345/87
• US Class Current: 345/87
• CPC Class Codes: G09G 2310/0205 Simultaneous scanning of several lines in flat panels
• CPC Class Codes: G09G 2310/061 for resetting or blanking
• CPC Class Codes: G09G 2320/0252 Improving the response speed
• 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 2340/16 Determination of a pixel data signal depending on the signal applied in the previous frame
• CPC Class Codes: G09G 3/2048 with addition of random noise to an image signal or to a gradation threshold
• CPC Class Codes: G09G 3/3614 Control of polarity reversal in general
• CPC Class Codes: G09G 3/3648 using an active matrix G09G3/367 - G09G3/3696 take precedence

Abstract

Based on each of video data repeatedly supplied to a pixel, a signal processing section generates video data (Dd) for an image display period to be supplied to the pixel and video data (Db) for a blanking period to be supplied to the pixel, and outputs the video data (Dd) and (Db) in a predetermined order. Further, when a gradation transition from a gradation indicated by previous video data (D(i,j,k−2)) supplied to the pixel to a gradation indicated by current video data (D(i,j,k)) supplied to the pixel indicates an increase in luminance, a generating circuit for a blanking period of the signal processing section outputs video data indicative of a gradation which is increased compared with a gradation indicated by gradation data for a blanking period in a steady state, the video data thus outputted being regarded as video data (Db(i,j,k−1)) for a blanking period. This allows for providing a display device capable of displaying moving images with high quality.

Claims

1. A method for driving a liquid crystal display device which uses a liquid crystal as a pixel, said method comprising the steps of:

(i) the step of displaying an image by supplying an output signal for an image display period to a the pixel of the liquid crystal display device so as to control luminance of the pixel, the output signal corresponding to a video signal indicative of an image to be displayed by the liquid crystal display device, the step (i) being performed repeatedly; and

(ii) the step, performed between the steps (i), of controlling blanking by supplying an output signal for a blanking period to the pixel so that luminance of the pixel does not exceed luminance of the pixel in at least one of the steps (i) between which the step (ii) is performed or so that luminance of the pixel becomes a luminance for dark display,

in the step (ii), when a change from first luminance to second luminance is a predetermined one where the first and second luminances are luminances indicated by output signals for image display periods in the steps (i) before and after the step (ii), the output signal for a blanking period being corrected so that the output signal for a blanking period has luminance which is corrected in a same direction as a direction of the change from the first luminance to the second luminance, the direction being a direction in which the luminance increases or decreases compared with an output signal for a blanking period obtained in a case where the first luminance is identical with the second luminance.

2. A method for driving a liquid crystal display device which uses a liquid crystal as a pixel, said method comprising the steps of:

(i) the step of displaying an image by supplying an output signal for an image display period to the pixel of the liquid crystal display device so as to control luminance of the pixel, the output signal corresponding to a video signal indicative of an image to be displayed by the liquid crystal display device, the step (i) being performed repeatedly; and

(ii) the step, performed between the steps (i), of controlling blanking by supplying an output signal for a blanking period to the pixel so that luminance of the pixel does not exceed luminance of the pixel in at least one of the steps (i) between which the step (ii) is performed or so that luminance of the pixel becomes a luminance for dark display,

in the step (ii), when a change from first luminance to second luminance is a predetermined one where the first and second luminances are luminances indicated by output signals for image display periods in the steps (i) before and after the step (ii), the output signal for a blanking period being corrected in accordance with the first luminance and the second luminance.

3. A method for driving a liquid crystal display device which uses a liquid crystal as a pixel, said method comprising the steps of:

(i) generating (a) gradation data for an image display period which is to be supplied to the pixel of the liquid crystal display device and (b) gradation data for a blanking period which is to be supplied to the pixel and is indicative of a gradation not brighter than a gradation indicated by the gradation data for an image display period or of a gradation for dark display, the generating being repeatedly performed based on gradation data supplied as gradation data to the pixel; and

(ii) outputting in an order the gradation data (a) and (b) generated in a corresponding step (i), the step (ii) being performed to correspond to each of the steps (i),

said method further comprising the step of, when a gradation transition from a gradation indicated by previous gradation data supplied to the pixel to a gradation indicated by current gradation data supplied to the pixel is a predetermined one, outputting gradation data indicative of a gradation which is corrected in a same direction as a direction of the gradation transition, the direction being a direction in which the gradation increases or decreases compared with gradation data for a blanking period obtained in a case where a gradation indicated by the previous gradation data and a gradation indicated by the current gradation data are identical with each other, the gradation data thus outputted being regarded as gradation data for a blanking period to be supplied between gradation data for an image display period supplied in the step (i) based on the previous gradation data and gradation data for an image display period supplied in the step (i) based on the current gradation data.

4. A method for driving a liquid crystal display device which uses a liquid crystal as a pixel, said method comprising the steps of:

(i) generating (a) gradation data for an image display period which is to be supplied to the pixel of the liquid crystal display device and (b) gradation data for a blanking period which is to be supplied to the pixel and is indicative of a gradation not brighter than a gradation indicated by the gradation data for an image display period or of a gradation for dark display, the generating being repeatedly performed based on gradation data supplied as gradation data to the pixel; and

(ii) outputting in an order the gradation data (a) and (b) generated in a corresponding step (i), the step (ii) being performed to correspond to each of the steps (i),

said method further comprising the step of, when a gradation transition from a gradation indicated by previous gradation data supplied to the pixel to a gradation indicated by current gradation data supplied to the pixel is a predetermined one, correcting gradation data for a blanking period supplied between gradation data for an image display period supplied in the step (i) based on the previous gradation data and gradation data for an image display period supplied in the step (i) based on the current gradation data, the correcting being performed based on the previous gradation data and the current gradation data.

5. A driving device for a liquid crystal display device which uses a liquid crystal as a pixel, the driving device (i) controlling, during each of repeated image display periods, luminance of the pixel of the liquid crystal display device by supplying to the pixel an output signal for an image display period which output signal varies depending on a video signal indicative of an image to be displayed, till a next image display period, by the liquid crystal display device, and (ii) controlling, during each blanking period between the image display periods, luminance of the pixel by supplying to the pixel an output signal for a blanking period, so that luminance of the pixel does not exceed luminance in at least one of the image display periods between which the blanking period exists or so that the luminance becomes a luminance for dark display,

said device comprising blanking controlling means for, when a change from first luminance to second luminance is a predetermined one where the first and second luminances are luminances indicated by output signals for image display periods supplied during the image display periods before and after the blanking period, correcting the output signal for a blanking period so that the output signal for a blanking period has luminance which is corrected in a same direction as a direction of the change from the first luminance to the second luminance, the direction being a direction in which the luminance increases or decreases compared with an output signal for a blanking period obtained in a case where the first luminance is identical with the second luminance.

11. The driving device as set forth in any one of claims 5 to 8, wherein

the predetermined change or the predetermined gradation transition indicates an increase in luminance of the pixel, and

when an increase in luminance is indicated, the blanking controlling means corrects the output signal or the gradation data for a blanking period so that luminance of the pixel increases during the blanking period.

13. The driving device as set forth any one of claims 5 to 8, wherein:

when a change or a gradation transition is not the predetermined one, the blanking controlling means controls an output signal for a blanking period or gradation data for a blanking period so that the output signal or the gradation data has a value.

15. The driving device as set forth in claim 5, 6, 7, or 8, wherein:

when a change or a gradation transition is not the predetermined one, the blanking controlling means controls an output signal or gradation data for a blanking period so that the output signal or the gradation data varies in accordance with an output signal or gradation data for an image display period adjacent to the blanking period.

16. The driving device as set forth in claim 15, wherein the blanking controlling means includes:

judging means for judging whether the gradation data for an image display period is in a steady state or not;

generating means for a steady state, for generating the gradation data for a blanking period, the gradation data for a blanking period being generated when the gradation data for an image display period is in a steady state;

blanking generating means for generating the gradation data for a blanking period, the gradation data for a blanking period being generated when the gradation data for an image display period changes; and

output means for selecting and outputting one of an output of the generating means for a steady state and an output of the blanking generating means, based on a result of judgment performed by the judging means.

22. A program causing a computer to function as each means as set forth in any one of claims 5 to 8.

23. A storage medium in which a program as set forth in claim 22 is stored.

24. A liquid crystal display device, comprising a driving device as set forth in any one of claims 5 to 8.

25. The liquid crystal display device as set forth in claim 24, said liquid crystal display device being a TV receiver.

26. The liquid crystal display device as set forth in claim 24, said liquid crystal display device being a liquid crystal monitor which displays a video signal.

6. A driving device for a liquid crystal display device which uses a liquid crystal as a pixel, the driving device (i) controlling, during each of repeated image display periods, luminance of the pixel of the liquid crystal display device by supplying to the pixel an output signal for an image display period which output signal varies depending on a video signal indicative of an image to be displayed, till a next image display period, by the liquid crystal display device, and (ii) controlling, during each blanking period between the repeated image display periods, luminance of the pixel by supplying to the pixel an output signal for a blanking period, so that luminance of the pixel does not exceed luminance in at least one of the image display periods between which the blanking period exists or so that the luminance becomes a luminance for dark display,

said device comprising blanking controlling means for, when a change from first luminance to second luminance is a predetermined one where the first and second luminances are luminances indicated by output signals for image display periods supplied during the image display periods between which the blanking period exists, correcting the output signal for a blanking period, based on the first luminance and the second luminance.

7. A driving device for a liquid crystal display device which uses a liquid crystal as a pixel, the driving device (i) generating (a) gradation data for an image display period which is to be supplied to the pixel of the liquid crystal display device and (b) gradation data for a blanking period which is to be supplied to the pixel and is indicative of a gradation not brighter than a gradation indicated by the gradation data for an image display period or of a gradation for dark display, the gradation data (a) and (b) being generated based on each of gradation data repeatedly supplied to the pixel, and (ii) outputting the gradation data (a) and (b) in an order,

said device comprising blanking controlling means for, when a gradation transition from a gradation indicated by previous gradation data supplied to the pixel to a gradation indicated by current gradation data supplied to the pixel is a predetermined one, outputting gradation data indicative of a gradation which is corrected in a same direction as a direction of the gradation transition, the direction being a direction in which the gradation increases or decreases compared with gradation data for a blanking period obtained in a case where a gradation indicated by the previous gradation data and a gradation indicated by the current gradation data are identical with each other, the gradation data thus outputted being regarded as gradation data for a blanking period to be supplied between gradation data for an image display period generated based on the previous gradation data and gradation data for an image display period generated based on the current gradation data.

9. The driving device as set forth in claim 7 or 8, wherein

the blanking controlling means includes storage means for storing data indicative of the gradation data for a blanking period corresponding to a combination of the previous gradation data and the current gradation data, and

the blanking controlling means corrects the gradation data for a blanking period based on the data.

10. The driving device as set forth in claim 9, wherein the blanking controlling means further includes calculating means for, when only data indicative of the gradation data for a blanking period corresponding to a combination of the previous gradation data and the current gradation data is stored in the storage means, calculating, by interpolating the data, the gradation data for a blanking period corresponding to a combination other than the combination.

12. The driving device as set forth in claim 7 or 8, further comprising generating means for generating, as the gradation data for an image display period, gradation data identical with supplied gradation data.

14. The driving device as set forth in claim 7 or 8, wherein

the supplied gradation data is indicative of one of 256 gradations, and

when a gradation transition is not the predetermined one, the blanking controlling means controls the gradation data for a blanking period so that the gradation data has a value of more than 0-gradation and not more than 32-gradation.

17. The driving device as set forth in claim 7 or 8, wherein

video data indicative of a gradation displayed by a the pixel is supplied to the driving device as video data to the pixel, and

when a gradation transition is not the predetermined one, the blanking controlling means controls the gradation data for a blanking period so that the gradation data is a multiplication of the gradation indicated by the video data and a constant value.

18. The driving device as set forth in claim 17, wherein the multiplication of the gradation indicated by the video data and the constant value is ½

or less of the gradation indicated by the video data.

19. The driving device as set forth in claim 7 or 8, wherein

at least a part of the predetermined gradation transition indicates a decrease in luminance of the pixel, and

said device further comprising gradation converting means for converting the supplied gradation data so that the gradation data includes only a gradation brighter than a predetermined gradation.

20. The driving device as set forth in claim 19, wherein

the gradation converting means converts the supplied gradation data so that the gradation data has a deeper gradation depth and the gradation converting means outputs the gradation data thus converted, and

the gradation converting means includes rounding means for adding noise information to the gradation data converted by the gradation converting means and then rounding the gradation data to which the noise information is added.

21. The driving device as set forth in claim 19, wherein the gradation converting means converts a gamma value of gamma characteristics of the supplied gradation data to a larger value.

27. The liquid crystal driving device as set forth in claim 20, wherein the gradation converting means converts a gamma value of gamma characteristics of the supplied gradation data to a larger value.

8. A driving device for a liquid crystal display device which uses a liquid crystal as a pixel, the driving device (i) generating (a) gradation data for an image display period which is to be supplied to the pixel of the liquid crystal display device and (b) gradation data for a blanking period which is to be supplied to the pixel and is indicative of a gradation not brighter than a gradation indicated by the gradation data for an image display period or of a gradation for dark display, the gradation data (a) and (b) being generated based on each of gradation data repeatedly supplied to the pixel, and (ii) outputting the gradation data (a) and (b) in an order,

said device comprising blanking controlling means for, when a gradation transition from a gradation indicated by previous gradation data supplied to the pixel to a gradation indicated by current gradation data supplied to the pixel is a predetermined one, correcting gradation data for a blanking period supplied between gradation data for an image display period generated based on the previous gradation data and gradation data for an image display period generated based on the current gradation data, the gradation data for a blanking period being corrected based on the previous gradation data and the current gradation data.