Correction characteristic determining device, correction characteristic determining method, and display device

• US 20030117414A1
• Filed: 12/10/2002
• Published: 06/26/2003
• Est. Priority Date: 12/21/2001
• Status: Active Grant

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Sasaki, Takashi
• Granted Patent: US 7,110,001 B2
• Time in Patent Office: Days
• US Class Current: 345/589
• CPC Class Codes: G09G 2320/0276 for the purpose of adaptation to the characteristics of a display device, i.e. gamma correction
• CPC Class Codes: G09G 3/006 Electronic inspection or testing of displays and display drivers, e.g. of LED or LCD displays testing individual LED's G01R31/2635; testing lamps G01R31/44; testing of optical features of LCD displays G02F1/1309
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers

Abstract

A correction characteristic determining device provided with (a) data converting means for converting measured data, indicative of an emission condition of a liquid crystal panel, into brightness data of three primary colors by using a conversion matrix, and (b) correction characteristic determining means for determining the correction characteristic in accordance with a conversion result obtained by the data converting means, further includes a conversion matrix generator for generating a conversion matrix. The conversion matrix generator includes: matrix element generating means for generating a matrix element of an inverse matrix of the conversion matrix, in accordance with measured data obtained when the display means displays highest gray scales of respective primary colors; matrix element correcting means for correcting a matrix element that has been generated by the matrix element generating means based on measured data obtained when the display means displays a highest gray scale of white; and inverse matrix generating means for generating an inverse matrix of a matrix constituted of the matrix element that has been corrected. Thus, it is possible to provide the correction characteristic determining device which matches a correction characteristic of a liquid crystal device to a characteristic of a liquid crystal panel.

Claims

1. A correction characteristic determining device for determining a correction characteristic in a display device which corrects an image signal constituted of three primary color signals, and displays a color image in display means in accordance with thus corrected image signal, said correction characteristic determining device comprising:

data converting means for converting measured data, convertible into a tristimulus value, that indicates a result of measurement performed with respect to an emission condition of display in the display means, into brightness data of three primary colors, by using a conversion matrix;

correction characteristic determining means for determining the correction characteristic in accordance with a conversion result obtained by the data converting means; and

matrix generating means for generating the conversion matrix, wherein

said matrix generating means includes;

matrix element generating means for generating a matrix element of an inverse matrix of the conversion matrix, in accordance with measured data obtained when the display means displays highest gray scales of respective primary colors;

matrix element adjusting means for adjusting a matrix element that has been generated by the matrix element generating means in accordance with measured data obtained when the display means displays a highest gray scale of white; and

inverse matrix generating means for generating an inverse matrix of a matrix constituted of the matrix element that has been adjusted.

2. The correction characteristic determining device as set forth in claim 1, further comprising

target mixture ratio generating means for generating a mixture ratio of output brightness of the three primary colors, by converting target chromaticity data, convertible into a tristimulus value, that indicates target chromaticity required in setting display chromaticity in the display means, in accordance with the conversion matrix, wherein

the correction characteristic determining means includes highest gray scale determining means for determining target output brightness, corresponding to the highest gray scales of the respective primary color signals of the image signal, in accordance with (a) a result obtained by causing the data converting means to convert the measured data obtained when the display means displays the highest gray scale of white and (b) the target mixture ratio.

3. The correction characteristic determining device as set forth in claim 2, wherein

the highest gray scale determining means is such that, in accordance with (a) a ratio of brightness data of the respective primary colors that has been obtained by causing the data converting means to convert the measured data obtained when the display means displays the highest gray scale of white, and (b) the target mixture ratio, the highest gray scale determining means regards the brightness data of one primary color signal, being shortest, as the target output brightness corresponding to the highest gray scale value of the primary color signal, and regards the target output brightness as a reference value, so as to determine other target output brightness corresponding to highest gray scale values of other primary color signals in accordance with the target mixture ratio.

4. The correction characteristic determining device as set forth in claim 2, wherein

the correction characteristic determining means includes intermediate gray scale determining means that determines the target output brightness corresponding to a plurality of intermediate gray scale values of the respective primary color signals in accordance with (a) the target output brightness corresponding to the highest gray scale values of the respective primary color signals that have been determined by the highest gray scale determining means, and (b) a ratio of the target output brightness corresponding to the highest gray scale value that has been set in the display means and the target output brightness respectively corresponding to the intermediate gray scale values.

5. The correction characteristic determining device as set forth in claim 4, wherein

in the display means, a relationship between gray scale values of the respective primary color signals and output brightness is such that density of gray scale values employed as the intermediate gray scale values is made higher at a gray scale value area, at which variation of the output brightness is relatively small with respect to variation of the gray scale value, than at a gray scale value area, at which the variation of the output brightness is relatively large with respect to the variation of the gray scale value.

6. The correction characteristic determining device as set forth in claim 4, wherein

the correction characteristic determining means includes gray scale adjusting means for adjusting the target output brightness, corresponding to the intermediate gray scale values of the respective primary color signals, that has been determined by the intermediate gray scale determining means, in accordance with the result obtained by causing the data converting means to convert the measured data obtained when the display means displays the lowest gray scale of white.

7. The correction characteristic determining device as set forth in claim 6, wherein:

the intermediate gray scale values include a lowest gray scale value of white, and

as to each of the primary color signals, the gray scale adjusting means subtracts the result, obtained by causing the data converting means to convert the measured data obtained when the display means displays the lowest gray scale of white, from the target output brightness corresponding to the lowest gray scale of white that has been determined by the intermediate gray scale determining means, so as to obtain an adjustment parameter of the primary color signal, and

the gray scale adjusting means subtracts the adjustment parameter of the primary color signal from at least indisplayable target brightness so as to perform adjustment, the indisplayable target brightness being part of the target brightness corresponding to the intermediate gray scales determined by the intermediate gray scale determining means.

8. The correction characteristic determining device as set forth in claim 7, wherein

the gray scale adjusting means performs the adjustment with respect to part of the intermediate gray scale values, the part being not more than a threshold value which is set as an upper limit of the gray scale that should be adjusted.

9. The correction characteristic determining device as set forth in claim 4, further comprising gray scale value converting means for determining corrected gray scale values, corresponding to the highest gray scale values of the respective primary color signals and the plurality of intermediate gray scale values of the respective primary color signals, in accordance with (a) the target output brightness and (b) the result obtained by causing the data converting means to convert the measured data obtained when the display means displays the highest gray scale of white.

10. The correction characteristic determining device as set forth in claim 6, further comprising gray scale value converting means for determining corrected gray scale values, corresponding to the highest gray scale values of the respective primary color signals and the plurality of intermediate gray scale values of the respective primary color signals, in accordance with (a) the target output brightness and (b) the result obtained by causing the data converting means to convert the measured data obtained when the display means displays the highest gray scale of white.

11. A display device which corrects an image signal constituted of three primary color signals, and displays a color image in display means in accordance with thus corrected image signal,

said display device comprising:

storage means for storing corrected gray scale values determined by the correction characteristic determining device as set forth in claim 9;

and

signal converting means for converting the image signal into the corrected image signal in accordance with the corrected gray scale values that have been stored in the storage means.

12. A display device which corrects an image signal constituted of three primary color signals, and displays a color image in display means in accordance with thus corrected image signal,

said display device comprising:

storage means for storing corrected gray scale values determined by the correction characteristic determining device as set forth in claim 10;

and

signal converting means for converting the image signal into the corrected image signal in accordance with the corrected gray scale values that have been stored in the storage means.

13. The display device as set forth in claim 11, wherein the signal converting means generates the corrected image signal by interpolating the corrected gray scale values, that have been stored, corresponding to the image signal.

14. The display device as set forth in claim 12, wherein the signal converting means generates the corrected image signal by interpolating the corrected gray scale values, that have been stored, corresponding to the image signal.

15. A correction characteristic determining method for determining a correction characteristic in a display device which corrects an image signal constituted of three primary color signals, and displays a color image in display means in accordance with thus corrected image signal, said method comprising the steps of:

(i) converting measured data, convertible into a tristimulus value, that indicates a result of measurement performed with respect to an emission condition of display in the display means, into brightness data of three primary colors, by using a conversion matrix;

(ii) determining the correction characteristic in accordance with a conversion result obtained by the step (i); and

(iii) generating the conversion matrix before performing the step (i), wherein

the step (iii) includes the steps of;

(iii-a) generating a matrix element of an inverse matrix of the conversion matrix, in accordance with measured data obtained when the display means displays highest gray scales of respective primary colors;

(iii-b) adjusting a matrix element that has been generated by the step (iii-a) in accordance with measured data obtained when the display means displays a highest gray scale of white; and

(iii-c) generating an inverse matrix of a matrix constituted of the matrix element that has been adjusted.

16. The method as set forth in claim 15, further comprising the step of (iv) generating a mixture ratio of output brightness of the three primary colors, by converting target chromaticity data, convertible into a tristimulus value, that indicates target chromaticity required in setting display chromaticity in the display means, in accordance with the conversion matrix, wherein

the step (ii) includes the step of (ii-a) determining target output brightness, corresponding to the highest gray scales of the respective primary color signals of the image signal, in accordance with (a) a result obtained by causing the data converting means to convert the measured data obtained when the display means displays the highest gray scale of white and (b) the target mixture ratio.

17. The method as set forth in claim 16, wherein:

the step (ii) is such that, in accordance with (a) a ratio of brightness data of the respective primary colors that has been obtained by causing the data converting means to convert the measured data obtained when the display means displays the highest gray scale of white, and (b) the target mixture ratio, the brightness data of one primary color signal, being shortest, is regarded as the target output brightness corresponding to the highest gray scale value of the primary color signal, and the target output brightness is regarded as a reference value so as to determine other target output brightness corresponding to highest gray scale values of other primary color signals in accordance with the target mixture ratio.

18. The method as set forth in claim 16, wherein

the step (ii) includes the step of (ii-b) determining the target output brightness, corresponding to the intermediate gray scale values of the respective primary color signals, in accordance with (a) the target output brightness corresponding to the highest gray scale values of the respective primary color signals that have been determined by the highest gray scale determining means, and (b) a ratio of the target output brightness corresponding to the highest gray scale value that has been set in the display means and the target output brightness respectively corresponding to a plurality of intermediate gray scale values.

19. The method as set forth in claim 18, wherein

in the display means, a relationship between gray scale values of the respective primary color signals and output brightness is such that density of gray scale values employed as the intermediate gray scale values is made higher at a gray scale value area, at which variation of the output brightness is relatively small with respect to variation of the gray scale value, than at a gray scale value area, at which the variation of the output brightness is relatively large with respect to the variation of the gray scale value.

20. The method as set forth in claim 18, wherein

the step (ii) includes the step of (ii-c) adjusting the target output brightness corresponding to the intermediate gray scale values of the respective primary color signals, that have been determined by the intermediate gray scale determining means, in accordance with the result obtained by causing the data converting means to convert the measured data obtained when the display means displays the lowest gray scale of white.

21. The method as set forth in claim 20, wherein

the intermediate gray scale values include a lowest gray scale value of white, and

the step (ii-c) is such that, as to each of the primary color signals, the result, obtained by causing the data converting means to convert the measured data obtained when the display means displays the lowest gray scale of white, is subtracted from the target output brightness corresponding to a lowest gray scale of white that has been determined by the intermediate gray scale determining means, so as to obtain an adjustment parameter of the primary color signal, and

the adjustment parameter of the primary color signal is subtracted from at least indisplayable target brightness so as to perform adjustment, the indisplayable target brightness being part of the target brightness corresponding to the intermediate gray scales determined by the intermediate gray scale determining means.

22. The method as set forth in claim 21, wherein

the step (iii) is such that the adjustment is performed with respect to part of the intermediate gray scale values, the part being not more than a threshold value which is set as an upper limit of the gray scale that should be corrected.

23. The method as set forth in claim 18, further comprising the step of determining corrected gray scale values, corresponding to the highest gray scale values of the respective primary color signals and the intermediate gray scale values of the respective primary color signals, in accordance with (a) the target output brightness and (b) the result obtained by causing the data converting means to convert the measured data obtained when the display means displays the highest gray scale of white.

24. The method as set forth in claim 20, further comprising the step of (v) determining corrected gray scale values, corresponding to the highest gray scale values of the respective primary color signals and the intermediate gray scale values of the respective primary color signals, in accordance with (a) the target output brightness and (b) the result obtained by causing the data converting means to convert the measured data obtained when the display means displays the highest gray scale of white.

25. A display device which corrects an image signal constituted of three primary color signals, and displays a color image in display means in accordance with thus corrected image signal, a correction characteristic in said display device being determined by a correction characteristic determining method, wherein said method includes the steps of:

(i) converting measured data, convertible into a tristimulus value, that indicates a result of measurement performed with respect to an emission condition of display in the display means, into brightness data of three primary colors, by using a conversion matrix;

(ii) determining the correction characteristic in accordance with a conversion result obtained by the step (i); and

(iii) generating the conversion matrix before performing the step (i), wherein

the step (iii) includes the steps of;

(iii-a) generating a matrix element of an inverse matrix of the conversion matrix, in accordance with measured data obtained when the display means displays highest gray scales of respective primary colors;

(iii-b) adjusting a matrix element that has been generated by the step (iii-a) in accordance with measured data obtained when the display means displays a highest gray scale of white; and

(iii-c) generating an inverse matrix of a matrix constituted of the matrix element that has been adjusted.

26. A correction characteristic determining device for determining a correction characteristic in a display device which corrects an image signal, and displays an image in display means in accordance with thus corrected image signal, said correction characteristic determining device comprising:

target curve setting means for setting a target curve indicative of a relationship between a gray scale value of the image signal that has not been corrected and target output brightness, corresponding to the gray scale value, that should be displayed in the display means;

gray scale adjusting means for setting an adjustment parameter by subtracting an actual brightness value, obtained when the display means displays a lowest gray scale, from lowest target output brightness corresponding to a lowest gray scale value of the image signal in the target curve, and for adjusting the target curve by subtracting the adjustment parameter from at least target output brightness in the target curve which is less than the lowest target output brightness; and

gray scale value converting means for determining a relationship between the gray scale value, that has not been corrected, and the gray scale value, that has been corrected, in the image signal, in accordance with the target curve that has been adjusted by the gray scale adjusting means.

27. The correction characteristic determining device as set forth in claim 26, wherein

the gray scale correcting means performs the adjustment with respect to a gray scale, not more than a threshold value, that has been set as an upper limit of the gray scale value that should be subjected to the adjusted.

28. A correction characteristic determining method for determining a correction characteristic in a display device which corrects an image signal, and displays an image in display means in accordance with thus corrected image signal, said method comprising the steps of:

(I) setting a target curve indicative of a relationship between a gray scale value of the image signal that has not been corrected and target output brightness that should be displayed in the display means;

(II) setting an adjustment parameter by subtracting an actual brightness value, obtained when the display means displays a lowest gray scale, from lowest target output brightness corresponding to a lowest gray scale value of the image signal in the target curve, so as to adjust the target curve by subtracting the adjustment parameter from at least target output brightness in the target curve which is less than the lowest target output brightness; and

(III) determining a relationship between the gray scale value, that has not been corrected, and the gray scale value, that has been corrected, in the image signal, in accordance with the target curve that has been adjusted by the step (II).

29. The method as set forth in claim 28, wherein

the step (III) is such that the adjustment is performed with respect to a gray scale, not more than a threshold value, that has been set as an upper limit of the gray scale value that should be subjected to the adjustment.

30. A display device which corrects an image signal, and displays an image in display means in accordance with thus corrected image signal, a correction characteristic in said display device being determined by a correction characteristic determining method, wherein said method includes the steps of:

(I) setting a target curve indicative of a relationship between a gray scale value of the image signal that has not been corrected and target output brightness that should be displayed in the display means;

(II) setting an adjustment parameter by subtracting an actual brightness value, obtained when the display means displays a lowest gray scale, from lowest target output brightness corresponding to a lowest gray scale value of the image signal in the target curve, so as to adjust the target curve by subtracting the adjustment parameter from at least target output brightness less than the lowest target output brightness; and

(III) determining a relationship between the gray scale value, that has not been corrected, and the gray scale value, that has been corrected, in the image signal, in accordance with the target curve that has been adjusted by the step (II).