Display drive device and drive controlling method
(19)AUSTRALIAN PATENT OFFICE (54) Title Display drive device and drive controllingmethod (51)6 International Patent Classification(s) G09G 003/36 (21) Application No: 2003294181 (22) Application Date: 2003.12.25 (87) WIPO No: WO04/059603 (30) Priority Data (31) Number (32) Date (33) Country 2002-376241 2002.12.26 JP (43) Publication Date : 2004 .07.22 (43) Publication Journal Date : 2004 .08.26 (71) Applicant(s) CASIO COMPUTER CO., LTD. (72) Inventor(s) Harada, Takahiro (-1-1) Application NoAU2003294181 A8(19)AUSTRALIAN PATENT OFFICE (54) Title Display drive device and drive controllingmethod (51)6 International Patent Classification(s) G09G 003/36 (21) Application No: 2003294181 (22) Application Date: 2003.12.25 (87) WIPO No: WO04/059603 (30) Priority Data (31) Number (32) Date (33) Country 2002-376241 2002.12.26 JP (43) Publication Date : 2004 .07.22 (43) Publication Journal Date : 2004 .08.26 (71) Applicant(s) CASIO COMPUTER CO., LTD. (72) Inventor(s) Harada, Takahiro -1- A display drive device applied to a display device which drives a display panel (110) comprising a plurality of display pixels (Px) which comprises a gradation voltage setting circuit (40a, 40c) which sets a plurality of gradation voltages and voltage ranges according to each luminosity gradation of the display data, which reverses the gradation voltages for each luminosity gradation of the display data in a predetermined period while providing a change characteristic of the center voltage in reversal of the gradation voltages for each luminosity gradation corresponding to the change inclination of the field through voltage produced when the display signal voltage of each luminosity gradation is applied, and which maintains this change characteristic constant for changing the voltage range value; and a gradation conversion circuit (30a, 30d) which produces display signal voltages based on gradation voltages corresponding to the luminosity gradations of the display data. CLAIMS 1. A display drive device which drives a display panel comprising a plurality of display pixels based on display data composed of digital signals comprising at least: a gradation voltage setting circuit (40a, 40c) comprising: a means which sets a plurality of gradation voltages corresponding to each luminosity gradation of the display data based on the highest reference voltage and lowest reference voltage, and sets the voltage range of these gradation voltages ; a means which reverses each gradation voltage value for each luminosity gradation of the display data in a predetermined period; a means which changes the voltage range value according to reversal of the gradation voltages; a means which provides a predetermined change characteristic value of the center voltage in reversal of the gradation voltages for each luminosity gradation;STDC0424 and a means which maintains the change characteristic constant for changing the voltage range value; a gradation conversion circuit (30a, 30d) which produces a display signal voltage based on the gradation voltages corresponding to the luminosity gradations of the display data; a display signal voltage output circuit (20) which applies the display signal voltage to the display pixels. <Desc/Clms Page number 47> 2. The display drive device according to claim 1, wherein the gradation voltage setting circuit (40a, 40c) comprises a means which sets the highest gradation voltage and lowest gradation voltage which regulate the voltage range of the display signal voltage based on the highest reference voltage and lowest reference voltage.
3. The display drive device according to claim 2, wherein the gradation voltage setting circuit (40a, 40c) comprises a voltage divider circuit (Rsa, Rsd, Rse) which applies the highest gradation voltage and lowest gradation voltage at both ends, performs voltage division of the potential difference between the highest gradation voltage and the lowest gradation voltage in a plurality of stages, and produces a plurality of gradation voltages.
4. The display drive device according to claim 3, wherein the voltage divider circuit (Rsa, Rsd, Rse) consists of a plurality of resistance elements connected in series with the highest gradation voltage and the lowest gradation voltage is applied at both ends of these plurality of resistance elements.
5. The display drive device according to claim 3, wherein the gradation conversion circuit (30a, 30d) comprises a gradation voltage selection circuit which selects the gradation voltage corresponding to the luminosity gradations of the display data <Desc/Clms Page number 48> from a plurality of gradation voltages produced by the voltage divider circuit (Rsa, Rsd, Rse) and makes these selected gradation voltages be the display signal voltage.
6. The display drive device according to claim 2, wherein the gradation voltage setting circuit (40a, 40c) comprises: a means which sets the first highest gradation voltage and lowest gradation voltage which regulate the voltage range in one side of the reverse gradation voltages as the highest gradation voltage and lowest gradation voltage; a means which sets the second highest gradation voltage and lowest gradation voltage which regulate the voltage range in the other side of the reverse gradation voltages; a means which sets the second highest gradation voltage and lowest gradation voltage as the value changed in the opposite direction to each other by a correction voltage which has a predetermined voltage value to the first highest gradation voltage and lowest gradation voltage.
7. The display drive device according to claim 6, wherein a plurality of display pixels (Px) of the display panel (110) are liquid crystal display pixels with liquid crystal molecules filled between the counter electrode and the pixel electrode where the display signal voltage is applied; and the correction voltage is the voltage corresponding to the voltage difference of the field through voltage produced <Desc/Clms Page number 49> when the display signal voltage corresponding to the highest gradation voltage and the lowest gradation voltage to the display pixels is applied.
8. The display drive device according to claim 6, wherein the gradation voltage setting circuit (40a) comprises a gradation voltage switching circuit (SWA, SWB) which alternately switches the first highest gradation voltage and lowest gradation voltage with the second highest gradation voltage and lowest gradation voltage according to reversal of the gradation voltages of the highest gradation voltage and the lowest gradation voltage which is applied at both ends of the voltage divider circuit (Rsa).
9. The display drive device according to claim 8, wherein the gradation voltage switching circuit (SWA, SWB) comprises a switching element which alternately selects either the highest reference voltage or the lowest reference voltage according to reversal of the gradation voltages.
10. The display drive device according to claim 6, wherein the voltage divider circuit comprises: a first voltage divider circuit (Rsd) where the first highest reference voltage and lowest reference voltage is applied at both ends; and a second voltage divider circuit (Rse) where the second highest reference voltage and lowest reference voltage is applied <Desc/Clms Page number 50> at both ends ; and a gradation voltage setting circuit (40c) comprises a voltage divider circuit switching circuit (SWC, SWD) which selects either the first voltage divider circuit (Rsd) or the second voltage divider circuit (Rse) according to reversal of the gradation voltages.
11. The display drive device according to claim 10, wherein the first voltage divider circuit (Rsd) and the second voltage divider circuit (Rse) have different voltage division characteristics to each other.
12. The display drive device according to claim 1, wherein the change characteristic of the center voltage in reversal of the gradation voltages for each luminosity gradation in the gradation voltage setting circuit has a linear change inclination to each of the luminosity gradations.
13. The display drive device according to claim 12, wherein a plurality of display pixels (Px) of the display panel (110) are liquid crystal display pixels with liquid crystal molecules filled between the counter electrode and the pixel electrode where the display signal voltage is applied; and the change characteristic of the center voltage in reversal of the gradation voltages for each luminosity gradation has a characteristic corresponding to the characteristic which <Desc/Clms Page number 51> performs straight line approximation of the change inclination of the field through voltage produced when the display signal voltage of each luminosity gradation to the display pixels is applied.
14. The display drive device according to claim 1, wherein the change characteristic of the center voltage in reversal of the gradation voltages for each luminosity gradation in the gradation voltage setting circuit has a nonlinear change inclination to each of the luminosity gradations.
15. The display drive device according to claim 14, wherein a plurality of display pixels (Px) of the display panel (110) are liquid crystal display pixels with liquid crystal molecules filled between the counter electrode and the pixel electrode where the display signal voltage is applied; and the change characteristic of the center voltage in reversal of the gradation voltages for each luminosity gradation has a characteristic corresponding to the change inclination of the field through voltage produced when the display signal voltage of each luminosity gradation to the display pixels is applied.
16. A display drive device which drives a display panel comprising a plurality of display pixels based on display data composed of digital signals comprising at least: <Desc/Clms Page number 52> a storage circuit (40) which stores information showing the relationship of the gradation voltages for each luminosity gradation of the display data; a gradation voltage setting circuit (40b) which sets a plurality of gradation voltages corresponding to each luminosity gradation of the display data based on the highest reference voltage and the lowest reference voltage :STDC0485 a gradation conversion circuit (30c) which produces a display signal voltage based on the gradation voltages corresponding to the luminosity gradations of the display data from a plurality of gradation voltages set by the gradation voltage setting circuit based on the relationship of the gradation voltages for each luminosity gradation stored in the storage circuit; and a display signal voltage output circuit (20) which applies the display signal voltage to the display pixels.
17. The display drive device according to claim 16, wherein the gradation conversion circuit (30c) in producing the display signal voltage comprising: a means which reverses the signal polarity of the display signal voltage based on the gradation voltages in a predetermined period on the basis of the relationship of the gradation voltages for each luminosity gradation stored in the storage circuit (40) and provides a predetermined change characteristic value of the center voltage in reverse signal <Desc/Clms Page number 53> polarity of the display signal voltage for each luminosity gradation; and a means which maintains the change characteristic constant for changing the highest reference voltage and lowest reference voltage.
18. The display drive device according to claim 17, wherein the gradation conversion circuit (30c) which produces the display signal voltage comprising: a means which sets the first highest gradation voltage and lowest gradation voltage which regulate the voltage range of the display signal in one side of the signal polarity based on the relationship of the gradation voltages for each luminosity gradation stored in the storage circuit (40); a means which sets the second highest gradation voltage and lowest gradation voltage which regulate the voltage range of the display signal in the other side of the signal polarity;STDC0268 a means which sets the second highest gradation voltage and lowest gradation voltage as the value changed in the opposite direction by a correction voltage which has a predetermined voltage value to the first highest gradation voltage and lowest gradation voltage.
19. The display drive device according to claim 18, wherein a plurality of display pixels (Px) of the display panel (110) are liquid crystal display pixels with liquid crystal molecules <Desc/Clms Page number 54> filled between the counter electrode and the pixel electrode where the display signal voltage is applied; and the correction voltage is the voltage corresponding to the voltage difference of the field through voltage produced when the display signal voltage corresponding to the highest gradation voltage and the lowest gradation voltage to the display pixels is applied.
20. The display drive device according to claim 17, wherein the change characteristic of the center voltage of the display signal voltage in reversal of the signal polarity for each luminosity gradation in the gradation conversion circuit (30c) has a linear change inclination to each luminosity gradation.
21. The display drive device according to claim 20, wherein a plurality of display pixels (Px) of the display panel (110) are liquid crystal display pixels with liquid crystal molecules filled between the counter electrode and the pixel electrode where the display signal voltage is applied; and the change characteristic of the center voltage of the display signal voltage in reversal of the signal polarity for each luminosity gradation has a characteristic corresponding to the characteristic which performs straight line approximation of the change inclination of the field through voltage produced when the display signal voltage of each luminosity gradation to the display pixels is applied. <Desc/Clms Page number 55> 22. The display drive device according to claim 17, wherein the change characteristic of the center voltage of the display signal voltage in reversal of the signal polarity for each luminosity gradation in the gradation conversion circuit (30c) has a nonlinear change inclination to each luminosity gradation.
23. The display drive device according to claim 22, wherein a plurality of display pixels (Px) of the display panel (110) are liquid crystal display pixels with liquid crystal molecules filled between the counter electrode and the pixel electrode where the display signal voltage is applied; and the change characteristic of the center voltage of the display signal voltage in reversal of the signal polarity for each luminosity gradation has a characteristic corresponding to the change inclination of the field through voltage produced when the display signal voltage of each luminosity gradation to the display pixels is applied.
24. The display drive device according to claim 16, wherein the gradation voltage setting circuit (40b) comprises a voltage divider circuit (Rsc) which applies the highest gradation voltage and lowest gradation voltage at both ends, performs voltage division of the potential difference between the highest reference voltage and the lowest reference voltage in a plurality of stages, and produces a plurality of gradation voltages. <Desc/Clms Page number 56> 25. The display drive device according to claim 24, wherein the gradation conversion circuit (30c) comprises a gradation voltage selection circuit which selects the gradation voltage corresponding to the luminosity gradations of the display data and makes these selected gradation voltages to the display signal voltage based on the relationship of the gradation voltages for each luminosity gradation stored in the storage circuit (40) from a plurality of gradation voltages produced by the voltage divider circuit (Rsc).
26. A display device which performs image display based on the display data composed of digital signals comprising at least: a display panel (110) in which two-dimensional array of a plurality of display pixels is performed; a scanning driver (120) comprising a means which sequentially scans the display pixel clusters of each line of the display panel and sets the selective state; a data driver (130) comprises a means which applies the produced display signal voltage to the display pixel clusters set as the selective state comprises: a means which sets a plurality of gradation voltages corresponding to each luminosity gradation of the display data based on the highest reference voltage and lowest reference voltage and sets the voltage range of these gradation voltages;STDC0811 a means which reverses each gradation voltage value <Desc/Clms Page number 57> for each luminosity gradation of the display data in a predetermined period; a means which changes the voltage range value according to reversal of the gradation voltages ; a means which provides a predetermined change characteristic value of the center voltage in reversal of the gradation voltages for each luminosity gradation; a means which maintains the change characteristic constant for changing the voltage range; a gradation conversion circuit (30a, 30c, 30d) means which produces a display signal voltage based on the gradation voltage corresponding to the luminosity gradations of the display data; and a display signal voltage output circuit (20) which applies the display signal voltage to the display pixels.
27. The display device according to claim 26, wherein the data driver (130) comprises a means which sets the highest gradation voltage and the lowest gradation voltage which regulate the voltage range of the display signal voltage based on the highest reference voltage and lowest reference voltage.
28. The display device according to claim 27, wherein the data driver (130) comprises a voltage divider circuit (Rsa, Rsc, Rsd, Rse) which applies the highest gradation voltage and lowest gradation voltage at both ends, performs voltage division of <Desc/Clms Page number 58> the potential difference between the highest gradation voltage and the lowest gradation voltage in a plurality of stages, and produces a plurality of gradation voltages.
29. The display device according to claim 28, wherein the voltage divider circuit (Rsa, Rsc, Rsd, Rse) consists of a plurality of resistance elements connected in series with the highest gradation voltage and the lowest gradation voltage is applied at both ends of these plurality of resistance elements.
30. The display device according to claim 28, wherein the data driver (130) in the gradation conversion circuit (30a, 30d) comprises a gradation voltage selection circuit which selects the gradation voltages corresponding to the luminosity of the display data from a plurality of gradation voltages produced by the voltage divider circuit (Rsa, Rsd, Rse) and makes these selected gradation voltages the display signal voltage.
31. The display device according to claim 28, wherein the data driver (130) comprises: a means which sets the first highest gradation voltage and lowest gradation voltage which regulate the voltage range in one side of the reverse gradation voltage as the highest gradation voltage and lowest gradation voltage; a means which sets the second highest gradation voltage and lowest gradation voltage which regulate the voltage range <Desc/Clms Page number 59> in the other side of the reverse gradation voltage; a means which sets the second highest gradation voltage and lowest gradation voltage as the value changed in the opposite direction to each other by a correction voltage which has a predetermined voltage value to the first highest gradation voltage and lowest gradation voltage.
32. The display device according to claim 31, wherein a plurality of display pixels (Px) of the display panel (110) are liquid crystal display pixels with liquid crystal molecules filled between the counter electrode and the pixel electrode where the display signal voltage is applied; and the correction voltage is the voltage corresponding to the voltage difference of the field through voltage produced when the display signal voltage corresponding to the highest gradation voltage and the lowest gradation voltage to the display pixels is applied.
33. The display device according to claim 31, wherein the data driver (130) comprises a gradation voltage switching circuit (SWA, SWB) which alternately switches the highest gradation voltage and lowest gradation voltage with the second highest gradation voltage and lowest gradation voltage corresponding to the highest gradation voltage and the lowest gradation voltage which is applied at both ends of the voltage divider circuit (Rsa) of the reverse gradation voltages. <Desc/Clms Page number 60> 34. The display device according to claim 33, wherein the gradation voltage switching circuit (SWA, SWB) comprises a switching element which alternately selects either the first highest reference voltage or the lowest reference voltage according to reversal of the gradation voltages.
35. The display device according to claim 31, wherein the data driver (130) further comprising: a storage circuit (40) which stores information showing the relationship of the gradation voltages for each luminosity gradation of the display data; a means which sets the first highest gradation voltage and lowest gradation voltage which regulate the voltage range of the display signal in one side of the reverse gradation voltages based on the relationship of the gradation voltages for each luminosity gradation stored in this storage circuit (40) ; and a means which sets the second highest gradation voltage and lowest gradation voltage which regulate the voltage range of the display signal in the other side of the reverse gradation voltages.
36. The display device according to claim 35, wherein gradation conversion circuit (30c) comprises a gradation voltage selection circuit which selects the gradation voltages corresponding to the luminosity gradations of the display data and makes this <Desc/Clms Page number 61> selected gradation voltage the display signal voltage based on the relationship of the gradation voltages for each luminosity gradation stored in the storage circuit (40) from a plurality of gradation voltages produced by the voltage divider circuit (Rsc).
37. The display device according to claim 28, wherein the voltage divider circuit consists of: a first voltage divider circuit (Rsd) where the first highest reference voltage and lowest reference voltage is applied at both ends; and a second voltage divider circuit (Rse) where the second highest reference voltage and lowest reference voltage is applied at both ends; the gradation voltage setting circuit comprises a voltage divider circuit switching circuit (SWC, SWD) which selects either the first voltage divider circuit (Rsd) or the second voltage divider circuit (Rse) according to reversal of the gradation voltages.
38. The display device according to claim 37, wherein the first voltage divider circuit (Rsd) and the second voltage divider circuit (Rse) have different voltage division characteristics to each other.
39. The display device according to claim 26, wherein the data <Desc/Clms Page number 62> driver (130) the change characteristic of the center voltage in reversal of the gradation voltages for each luminosity gradation has a linear change inclination according to each luminosity gradation.
40. The display device according to claim 39, wherein a plurality of display pixels (Px) of the display panel (110) are liquid crystal display pixels with liquid crystal molecules filled between the counter electrode and the pixel electrode where the display signal voltage is applied; and the change characteristic of the center voltage in reversal of the gradation voltages for each luminosity gradation has a characteristic corresponding to the characteristic which performs straight line approximation of the change inclination of the field through voltage produced when the display signal voltage of each luminosity gradation to the display pixels is applied.
41. The display device according to claim 28, wherein the data driver (130) the change characteristic of the center voltage in reversal of the gradation voltages for each luminosity gradation has a nonlinear change inclination according to the luminosity gradations.
4 2. The display device according to claim 41, wherein a plurality of display pixels (Px) of the display panel (110) are liquid <Desc/Clms Page number 63> crystal display pixels with liquid crystal molecules filled between the counter electrode and the pixel electrode where the display signal voltage is applied; and the change characteristic of the center voltage in reversal of the gradation voltages for each luminosity gradation has a characteristic corresponding to the change inclination of the field through voltage produced when the display signal voltage of each luminosity gradation to the display pixels is applied.
43. A drive controlling method for a display drive device which drives a display panel comprises a plurality of display pixels based on display data composed of digital signals includes at least: processing which produces a display signal voltage corresponding to the luminosity gradations of the display data; and processing which changes both the highest gradation voltage and the lowest gradation voltage in the opposite direction to each other for which the voltage range of the display signal voltage is regulated whenever this signal is reversed, providing a constant change characteristic value of the center voltage in reverse signal polarity of the display signal voltage for each luminosity gradation, while reversing the signal polarity of the display signal voltage in a predetermined period. <Desc/Clms Page number 64> 44. The drive controlling method for a display drive device according to claim 43 further includes processing which performs switch control whenever the signal polarity is reversed, based on the highest reference voltage and lowest reference voltage: processing which sets the first highest gradation voltage and lowest gradation voltage and produces the display signal voltage according to the luminosity gradations of the display data; and processing which sets the second highest gradation voltage and lowest gradation voltage which has the value changed in the opposite direction to each other by a correction voltage which has a predetermined voltage value for the first highest gradation voltage and lowest gradation voltage and produces the display signal voltage according to the luminosity gradations of the display data.
45. The drive controlling method for a display drive device according to claim 42, wherein a plurality of display pixels (Px) of the display panel (110) are liquid crystal display pixels with liquid crystal molecules filled between the counter electrode and the pixel electrode where the display signal voltage is applied; and the correction voltage is the voltage corresponding to the voltage difference of the field through voltage produced when the display signal voltage corresponding to the highest gradation voltage and the lowest gradation voltage to the display <Desc/Clms Page number 65> pixels is applied.
46. The drive controlling method for a display drive device according to claim 43, wherein the change characteristic of the center voltage in reversal of the gradation voltages for each luminosity gradation has a linear change inclination according to each luminosity gradation.
47. The drive controlling method for a display drive device according to claim 43, wherein the gradation voltage setting circuit the change characteristic of the center voltage in reversal of the gradation voltages for each luminosity gradation has a nonlinear change inclination according to the luminosity gradations.
48. The drive controlling method for a display drive device according to claim 47, wherein a plurality of display pixels (Px) of the display panel (110) are liquid crystal display pixels with liquid crystal molecules filled between the counter electrode and the pixel electrode where the display signal voltage is applied; and the change characteristic of the center voltage in reversal of the gradation voltages for each luminosity gradation has a characteristic corresponding to the change inclination of the field through voltage produced when the display signal voltage of each luminosity gradation to the display pixels is <Desc/Clms Page number 66> applied.