Display device, liquid crystal monitor, liquid crystal television receiver, and display method

• US 20050184944A1
• Filed: 01/21/2005
• Published: 08/25/2005
• Est. Priority Date: 01/21/2004
• 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: Miyata, Hidekazu, Tomizawa, Kazunari, Ishihara, Tomoyuki
• Granted Patent: US 7,932,915 B2
• Time in Patent Office: Days
• US Class Current: 345/89
• CPC Class Codes: G09G 2300/0443 with several sub-pixels for the same colour in a pixel, not specifically used to display gradations G09G3/364 takes precedence
• CPC Class Codes: G09G 2300/0447 for multi-domain technique to improve the viewing angle in a liquid crystal display, such as multi-vertical alignment [MVA]
• CPC Class Codes: G09G 2300/0876 Supplementary capacities in pixels having special driving circuits and electrodes instead of being connected to common electrode or ground; Use of additional capacitively coupled compensation electrodes
• 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 2320/028 by changing the viewing angle properties, e.g. widening the viewing angle, adapting the viewing angle to the view direction
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2360/18 Use of a frame buffer in a display terminal, inclusive of the display panel
• CPC Class Codes: G09G 3/2029 the sub-frames having non-binary weights
• CPC Class Codes: G09G 3/2081 with combination of amplitude modulation and time modulation space and time error diffusion G09G3/2066
• CPC Class Codes: G09G 3/3611 Control of matrices with row and column drivers
• 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

A control section divides a single frame so that a ratio of a period corresponding to a latter sub-frame and a period corresponding to a former sub-frame ranges from 1:3 to 1:7. A divisional point of the frame is a point which allows each of the latter sub-frame and the former sub-frame to minimize a difference between an actual brightness and an expected brightness. The frame may thus be divided at the point where the difference is largest in the normal hold display, so that it is possible to minimize the difference at this point. On this account, it is possible to reduce the difference in a single frame substantially by half as compared with an arrangement for carrying out the normal hold display, and thereby suppress the excess brightness caused by the difference.

Claims

1. A display device, wherein a single frame is divided into first and second sub-frames so as to display an image, said display device comprising:

a display section for displaying an image whose luminance is based on a luminance gradation of a display signal; and

a control section for generating a first display signal in the first sub-frame and a second display signal in the second sub-frame so that division of the frame does not vary a total luminance outputted from the display section in a single frame, and for outputting the first and second display signals to the display section, wherein

the control section is adapted to adjust a luminance gradation of the first display signal and set a luminance gradation of the second display signal to a minimum value or a value smaller than a first predetermined value to display an image whose brightness is relatively low, and

the control section is adapted to set the luminance gradation of the first display signal to a maximum value or a value larger than a second predetermined value and adjust the luminance gradation of the second display signal to display an image whose brightness is relatively high, and

the control section is adapted to divide the frame so that a ratio of a period corresponding to the first sub-frame and a period corresponding to the second sub-frame is at least one of 1;

n and n;

1, wherein n is a number more than 1.

2. The display device as set forth in claim 1, wherein n is in a range not more than 7.

3. The display device as set forth in claim 1, wherein

the second predetermined value is 80% of the maximum gradation.

4. The display device as set forth in claim 1, wherein:

n is an integer, and

the control section calculates Lt represented by

Lt=(1/(n+1)) {circumflex over ( 

)}(1/γ

)×

Lmax

in accordance with (i) a maximum luminance Lmax of an image displayed in a single frame and (ii) a predetermined value γ

, and

the control section determines whether or not a frame gradation L indicative of a luminance gradation of a display signal in a normal hold display is not more than Lt, and

the control section sets a luminance gradation F of the second display signal to be minimum (0) and sets a luminance gradation R of the first display signal so that

R=(1/(n+1)) {circumflex over ( 

)}(1/γ

)×

L

when the frame gradation L is not more than Lt, and

the control section sets the luminance gradation R of the first display signal to be maximum and sets the luminance gradation F of the second display signal so that

F=((L{circumflex over ( 

)}γ

−

(1/(n+1))×

Lmax{circumflex over ( 

)}γ

)) {circumflex over ( 

)}(1/γ

)

when the frame gradation L is more than Lt.

5. The display device as set forth in claim 1, wherein

the control section is designed so as to alternately output the first display signal and the second display signal to the display section with a difference of 1/(n+1) cycle.

6. The display device as set forth in claim 1, wherein the display section is adapted to cause a liquid crystal panel to display an image.

7. The display device as set forth in claim 6, wherein the liquid crystal panel is in a VA mode.

8. The display device as set forth in claim 6, wherein the liquid crystal panel is normally black.

9. The display device as set forth in claim 6, wherein

the control section is designed to determine whether a liquid crystal response speed of the liquid crystal panel satisfies conditions (c) and (d) or not, and the control section is adapted to carry out normal hold display when the conditions (c) and (d) are not satisfied,

said conditions (c) and (d) being as follows:

(c) when a voltage signal maximizing a brightness is provided to a liquid crystal displaying an image whose brightness is minimum, a voltage of the liquid crystal reaches a value not less than 90% of a voltage of the voltage signal within the period corresponding to the first sub-frame, and

(d) when a voltage signal minimizing a brightness is provided to a liquid crystal displaying an image whose brightness is maximum, a voltage of the liquid crystal reaches a value not more than 5% of a voltage of the voltage signal within the period corresponding to the first sub-frame.

10. The display device as set forth in claim 6, wherein the control section is designed to equalize polarities of a voltage, applied to liquid crystal, with each other in the first and second sub-frames and

wherein the control section is designed to differentiate the polarities of the voltage from each other between frames adjacent to each other.

11. The display device as set forth in claim 6, wherein

the control section is designed to differentiate polarities of a voltage, applied to liquid crystal, from each other between two sub-frames in a single frame, and wherein the control section is designed to equalize the polarities of the voltage with each other in a first sub-frame of a single frame and a second sub-frame of other frame adjacent to the first sub-frame.

12. The display device as set forth in claim 1, wherein:

the control section is set so as to generate the display signal by using (i) an image signal inputted from an outside and (ii) each of relation tables indicative of a relationship between the image signal and the display signal, and

the relation tables are provided in plurality so as to cover temperature ranges different from each other, and

the control section is designed so as to select a relation table corresponding to an environmental temperature and use the relation table thus selected.

13. The display device as set forth in claim 6, wherein the control section is designed so as to vary a polarity of a voltage applied to liquid crystal at a frame cycle.

23. A liquid crystal monitor, comprising:

the display device, as set forth in claim 1, whose display section is a liquid crystal panel; and

a signal input section for conveying an image signal to the control section, wherein the control section of the display device is designed to generate the display signal in accordance with the image signal.

27. A liquid crystal television receiver, comprising:

the display device, as set forth in claim 1, whose display section is a liquid crystal panel; and

a tuner section for selecting a channel of a television broadcasting signal to convey a television image signal of the channel thus selected to the control section, wherein the control section of the display device is designed to generate the display signal in accordance with the television image signal.

68. The display device as set forth in claim 1, wherein

the first predetermined value is 0.02% of the maximum gradation.

14. A display device, dividing a single frame into m number of sub-frames, where m is an integer not less than 2, so as to display an image, said display device comprising:

a display section for displaying an image whose luminance is based on a luminance gradation of a display signal; and

a control section for generating first to m-th display signals in first to m-th sub-frames so that division of the frame does not vary a total luminance outputted from the display section in a single frame and for outputting the first to m-th display signals to the display section, wherein

each of pixels provided on the display section varies its luminance according to a voltage of each of the first to m-th display signals,

each pixel has first and second sub-pixels connected to a single source line and a single gate line, and

the control section is designed to set a luminance of the first sub-pixel to a first luminance and to set a luminance of the second sub-pixel to a second luminance, different from the first luminance, with respect to at least one display signal voltage.

15. The display device as set forth in claim 14, wherein m is 2.

16. The display device as set forth in claim 14, wherein the control section is designed to set luminance gradations of the sub-pixels so that a total value of luminances outputted from both the sub-pixels is a luminance corresponding to the display signal.

17. The display device as set forth in claim 14, wherein

the sub-pixels are connected to auxiliary lines different from each other, and wherein each of the sub-pixels includes:

a pixel capacitor;

a switching element for applying a display signal, which has been applied to the source line, to the pixel capacitor when the gate line turns ON; and

an auxiliary capacitor connected to the pixel capacitor and each of the auxiliary lines, and wherein

the control section is adapted to differentiate auxiliary signals, flowing in the auxiliary lines connected to the sub-pixels, from each other so as to differentiate voltages, each of which is applied to the pixel capacitor of the sub-pixel, from each other.

18. The display device as set forth in claim 14, wherein

the display section is adapted to cause a liquid crystal panel to display an image, and

the control section is adapted to vary a polarity of a voltage applied to liquid crystal of the sub-pixel at a frame cycle.

19. The display device as set forth in claim 18, wherein

the control section is designed to reverse a phase of each of the auxiliary signals at the frame cycle.

24. A liquid crystal monitor, comprising:

the display device, as set forth in claim 14, whose display section is a liquid crystal panel; and

a signal input section for conveying an image signal to the control section, wherein the control section of the display device is designed to generate the display signal in accordance with the image signal.

28. A liquid crystal television receiver, comprising:

the display device, as set forth in claim 14, whose display section is a liquid crystal panel; and

a tuner section for selecting a channel of a television broadcasting signal to convey a television image signal of the channel thus selected to the control section, wherein the control section of the display device is designed to generate the display signal in accordance with the television image signal.

69. The display as set forth in claim 15, wherein

a ratio of a period corresponding to the first sub-frame and a period corresponding to the second sub-frame is 1:

n or n;

1, where n is a number more than 1.

20. A display device, dividing a single frame into m number of sub-frames, where m is an integer not less than 2, so as to display an image, said display device comprising:

a display section for displaying an image whose luminance is based on a luminance gradation of a display signal; and

a control section for generating first to m-th display signals in first to m-th sub-frames so that division of the frame does not vary a total luminance outputted from the display section in a single frame and for outputting the first to m-th display signals to the display section, wherein

the display section is set to cause a liquid crystal panel to display an image, and

the control section is designed to vary a polarity of a voltage applied to liquid crystal at a frame cycle.

25. A liquid crystal monitor, comprising:

the display device, as set forth in claim 20, whose display section is a liquid crystal panel; and

a signal input section for conveying an image signal to the control section, wherein the control section of the display device is designed to generate the display signal in accordance with the image signal.

29. A liquid crystal television receiver, comprising:

the display device, as set forth in claim 20, whose display section is a liquid crystal panel; and

a tuner section for selecting a channel of a television broadcasting signal to convey a television image signal of the channel thus selected to the control section, wherein the control section of the display device is designed to generate the display signal in accordance with the television image signal.

21. A display device, dividing a single frame into two sub-frames as first and second sub-frames so as to display an image, said display device comprising:

a display section for displaying an image whose luminance is based on a luminance gradation of a display signal; and

a control section for generating a first display signal in a first sub-frame and a second display signal in a second sub-frame so that division of the frame does not vary a total luminance outputted from the display section in a single frame and for outputting the first and second display signals to the display section at a doubled clock, wherein

the control section is set to;

adjust a luminance gradation of the first display signal and minimizes a luminance gradation of the second display signal in case of displaying an image whose brightness is low, and

maximize the luminance gradation of the first display signal and adjusts the luminance gradation of the second display signal in case of displaying an image whose brightness is high, and

divide the frame so that a ratio of a period corresponding to the first sub-frame and a period corresponding to the second sub-frame is at least one of 1;

n and n;

1, wherein n is a natural number not less than 1.

22. The display device as set forth in claim 21, wherein n is a natural number ranging from 3 to 7.

26. A liquid crystal monitor, comprising:

the display device, as set forth in claim 21, whose display section is a liquid crystal panel; and

a signal input section for conveying an image signal to the control section, wherein the control section of the display device is designed to generate the display signal in accordance with the image signal.

30. A liquid crystal television receiver, comprising:

the display device, as set forth in claim 21, whose display section is a liquid crystal panel; and

a tuner section for selecting a channel of a television broadcasting signal to convey a television image signal of the channel thus selected to the control section, wherein the control section of the display device is designed to generate the display signal in accordance with the television image signal.

31. A method of displaying an image by dividing a single frame into two sub-frames as first and second sub-frames, said method comprising an outputting step for generating a first display signal in the first sub-frame and a second display signal in the second sub-frame so that division of the frame does not vary a total luminance outputted from the display section in a single frame and for outputting the first and second display signals to the display section, wherein

the outputting step is such that:

a luminance gradation of the first display signal is adjusted and a luminance gradation of the second display signal is set to a minimum value or a value smaller than a first predetermined value for displaying an image whose brightness is relatively low, and

the luminance gradation of the first display signal is set to a maximum value or a value larger than a second predetermined value and the luminance gradation of the second display signal is adjusted for displaying an image whose brightness is relatively high, and

the frame is divided so that a ratio of a period corresponding to the first sub-frame and a period corresponding to the second sub-frame is at least one of 1;

n and n;

1, wherein n is a number more than 1.

32. A method of displaying an image by dividing a single frame into m number of sub-frames where m is an integer not less than 2, said method comprising an outputting step for generating first to m-th display signals in first to m-th sub-frames so that division of the frame does not vary a total luminance outputted from the display section in a single frame and for outputting the first to m-th display signals to the display section, wherein

each of pixels provided on the display section varies its luminance according to a voltage of each of the first to m-th display signals, and

the pixel has first and second sub-pixels connected to a single source line and a single gate line, and

the outputting step is such that:

a luminance of the first sub-pixel is set to a first luminance and a luminance of the second sub-pixel is set to a second luminance, different from the first luminance, with respect to at least one display signal voltage.

33. A method of displaying an image by dividing a single frame into m number of sub-frames where n is an integer not less than 2, said method comprising an outputting step for generating first to m-th display signals in first to m-th sub-frames so that division of the frame does not vary a total luminance outputted from the display section in a single frame and for outputting the first to m-th display signals to the display section, wherein

the display section is set so as to cause a liquid crystal panel to display an image, and

the outputting step is such that a polarity of a voltage applied to liquid crystal is varied at a frame cycle.

34. A method of displaying an image by dividing a single frame into two sub-frames as first and second sub-frames, said method comprising an outputting step for generating a first display signal in a first sub-frame and a second display signal in a second sub-frame so that division of the frame does not vary a total luminance outputted from the display section in a single frame and for outputting the first and second display signals to the display section at a doubled clock, wherein

the outputting step is such that:

a luminance gradation of the first display signal is adjusted and a luminance gradation of the second display signal is minimized in case of displaying an image whose brightness is low, and

the luminance gradation of the first display signal is maximized and the luminance gradation of the second display signal is adjusted in case of displaying an image whose brightness is high, and

the frame is divided so that a ratio of a period corresponding to the first sub-frame and a period corresponding to the second sub-frame is at least one of 1;

n and n;

1, wherein n is a natural number not less than 1.

35. The method as set forth in claim 34, wherein n is a natural number ranging from 3 to 7.

36. A display driving method, comprising:

supplying an image signal of a gradation level; and

displaying the image signal at the supplied gradation level, wherein a frame of the image signal is supplied in a plurality of sub-frames, and wherein at least two of the sub-frames include periods of different lengths.

37. The display driving method of claim 36, wherein

the image signal is displayed on an LCD display device.

38. The display driving method of claim 36, wherein

the plurality of sub-frames include at least one of a sub-frame of a maximum gradation level or a value larger than a second predetermined value, and a sub-frame of a minimum gradation level or a value smaller than a first predetermined value.

39. The display driving method of claim 37, wherein

the plurality of sub-frames include at least one of a sub-frame of a maximum gradation level or a value larger than a second predetermined value, and a sub-frame of a minimum gradation level or a value smaller than a first predetermined value.

40. An apparatus for displaying an image of an image signal, comprising:

a control section, adapted to supply a gradation level of the image signal; and

a display section, adapted to display the image signal at the supplied gradation level, wherein a frame of the image signal is supplied in a plurality of sub-frames, and wherein a period of at least two of the sub-frames different from one another.

41. The apparatus of claim 40, wherein the display section includes an LCD display device.

42. The apparatus of claim 40, wherein the plurality of sub-frames include at least one of a sub-frame of a maximum gradation level or a value larger than a second predetermined value, and a sub-frame of a minimum gradation level or a value smaller than a first predetermined value.

43. The apparatus of claim 41, wherein the plurality of sub-frames include at least one of a sub-frame of a maximum gradation level or a value larger than a second predetermined value, and a sub-frame of a minimum gradation level or a value smaller than a first predetermined value.

44. A display driving method, comprising:

supplying an image signal of a gradation level, wherein a frame of the image signal is divided into a plurality of sub-frames, the periods of at least two of the sub-frames being different from one another; and

reversing a polarity of the supplied image signal at a frame cycle; and

displaying the image signal at the supplied gradation level, inclusive of any polarity reversal.

45. The display driving method of claim 44, wherein

the image signal is displayed on an LCD display device.

46. The display driving method of claim 44, wherein

the plurality of sub-frames include at least one of a sub-frame of a maximum gradation level or a value larger than a second predetermined value, and a sub-frame of a minimum gradation level or a value smaller than a first predetermined value.

47. The display driving method of claim 45, wherein

the plurality of sub-frames include at least one of a sub-frame of a maximum gradation level or a value larger than a second predetermined value, and a sub-frame of a minimum gradation level or a value smaller than a first predetermined value.

48. The display driving method of claim 44, wherein

the display driving method is used in a pixel divisional driving system including at least two sub-pixels for each display pixel.

49. The display driving method of claim 48, wherein

one of the sub-pixels is a relatively dark sub-pixel and wherein one of the sub-pixels is a relatively bright sub-pixel.

50. An apparatus for displaying an image of an image signal, comprising:

a control section, adapted to supply a gradation level of the image signal, wherein a frame of the image signal is divided into a plurality of sub-frames, the periods of at least two of the sub-frames being different from one another; and

a display section, adapted to reverse a polarity of the supplied image signal at a frame cycle, and adapted to display the image signal at the supplied gradation level, inclusive of any polarity reversal.

51. The apparatus of claim 50, wherein the display section includes an LCD display device.

52. The apparatus of claim 50, wherein the plurality of sub-frames include at least one of a sub-frame of a maximum gradation level or a value larger than a second predetermined value, and a sub-frame of a minimum gradation level or a value smaller than a first predetermined value.

53. The apparatus of claim 51, wherein the plurality of sub-frames include at least one of a sub-frame of a maximum gradation level or a value larger than a second predetermined value, and a sub-frame of a minimum gradation level or a value smaller than a first predetermined value.

54. The apparatus of claim 53, wherein the display section includes an arrangement of sub-pixels, including at least two sub-pixels for each display pixel.

55. The apparatus of claim 54, wherein one of the sub-pixels is a relatively dark sub-pixel and wherein one of the sub-pixels is a relatively bright sub-pixel.

56. A display driving method, comprising:

supplying an image signal of a gradation level, wherein a frame of the image signal is divided into a plurality of sub-frames; and

displaying the image signal, at the supplied gradation level, on an image display section including an arrangement of sub-pixels including at least two sub-pixels for each display pixel, wherein a phase of a supplemental signal is varied in conjunction with a polarity of the image signal, and wherein the phase is varied and the polarity is reversed at each frame cycle.

57. The display driving method of claim 56, wherein

the image signal is displayed on an LCD display device.

58. The display driving method of claim 56, wherein

the plurality of sub-frames include at least one of a sub-frame of a maximum gradation level or a value larger than a second predetermined value, and a sub-frame of a minimum gradation level or a value smaller than a first predetermined value.

59. The display driving method of claim 57, wherein

the plurality of sub-frames include at least one of a sub-frame of a maximum gradation level or a value larger than a second predetermined value, and a sub-frame of a minimum gradation level or a value smaller than a first predetermined value.

60. The display driving method of claim 56, wherein

one of the sub-pixels is a relatively dark sub-pixel and

wherein one of the sub-pixels is a relatively bright sub-pixel.

61. The display driving method of claim 56, wherein

the periods of at least two of the sub-frames are different from one another.

62. An apparatus for displaying an image of an image signal, comprising:

a control section, adapted to supply a gradation level of the image signal, wherein a frame of the image signal is divided into a plurality of sub-frames; and

a display section, adapted to display the image signal, at the supplied gradation level, the image display section including an arrangement of sub-pixels including at least two sub-pixels for each display pixel, wherein a phase of a supplemental supplied signal is varied in conjunction with a polarity of the supplied image signal, and wherein the phase is varied and the polarity is reversed at each frame cycle.

63. The apparatus of claim 63, wherein the display section includes an LCD display device.

64. The apparatus of claim 63, wherein the plurality of sub-frames include at least one of a sub-frame of a maximum gradation level or a value larger than a second predetermined value, and a sub-frame of a minimum gradation level or a value smaller than a first predetermined value.

65. The apparatus of claim 63, wherein the plurality of sub-frames include at least one of a sub-frame of a maximum gradation level or a value larger than a second predetermined value, and a sub-frame of a minimum gradation level or a value smaller than a first predetermined value.

66. The apparatus of claim 63, wherein one of the sub-pixels is a relatively dark sub-pixel and wherein one of the sub-pixels is a relatively bright sub-pixel.

67. The apparatus of claim 63, wherein the periods of at least two of the sub-frames are different from one another.