KR20070115772A - Display device and driving method thereof - Google Patents

Abstract

A display device and a driving method thereof are provided to increase brightness of a light source unit corresponding to a low-brightness emission and display area unit to obtain low display brightness for a dark image uniformly. A display part is formed by a transmissive LCD having a display area(11) including pixels arranged in a matrix configuration. A backlight(40) includes light source units(42) individually disposed corresponding to a plurality of display area units constituting the display area, and illuminates a back surface of the display part. A driving unit drives the display part and the backlight on the basis of an input signal from the outside. The driving unit includes a controller(70) controlling an illumination state of the light source unit corresponding to the display area unit on the basis of a maximum input signal within the display area unit, which has a maximum value of an input signal corresponding to each display area unit. The controller checks whether a low-brightness emission and display area unit having the maximum input value in the display area unit which is lower than a first set value exists, and checks whether a high-brightness emission and display area unit having the maximum input signal in the display area unit which is the same as or higher than a second set value which is greater than the first set value exists. When the high-brightness emission and display area unit exists around the low-brightness emission and display area unit, the controller increases brightness of the light source unit corresponding to the low-brightness emission and display area unit.

Description

Display device and driving method thereof

1A, 1B, 1C, and 1D show light transmittances (opening ratios) in pixels constituting a display area unit for explaining a method of driving the display device in Example 1 or Example 2, respectively. Is a diagram schematically illustrating a state of, a state of light source luminance, and a state of display luminance.

2A, 2B, 2C, and 2D are diagrams illustrating the light transmittance (opening ratio) in the pixels constituting the display area unit for explaining the method of driving the display device according to the third embodiment, respectively. It is a figure which shows typically the state, the state of a light source luminance, and a display luminance state.

3 is a flowchart for explaining a method of driving the display device according to the first embodiment.

4 is a conceptual diagram of a display device including a color liquid crystal display device and a backlight suitable for use in the embodiment.

5 is a conceptual diagram of a portion of a drive circuit suitable for use in the embodiment.

FIG. 6A is a diagram schematically showing the arrangement and arrangement of light emitting diodes and the like in the backlight of the embodiment, and FIG. 6B is a schematic diagram of a display device including the color liquid crystal display and the backlight of the embodiment. Some cross section.

7 is a schematic partial sectional view of a color liquid crystal display device.

8A and 8B show display luminance and second prescribed values when it is assumed that a control signal corresponding to an input signal having a value equal to the value (x _{U -max} ) of the display area unit / maximum input signal is supplied to the pixel. As (y ₂ ) is obtained by the light source unit, it is a conceptual diagram for explaining a state in which the light source luminance Y ₂ of the light source unit is increased or decreased under the control of the driving unit.

FIG. 9A is a diagram schematically showing a relationship between a value obtained by multiplying a value of an input signal input to a liquid crystal display driving circuit to drive a subpixel by 2.2 (xx ^2.2 ) and a duty ratio (= t _ON / t _Const ); FIG. 9B is a diagram schematically showing a relationship between the value X of the control signal and the display luminance y for controlling the light transmittance of the subpixel.

10A and 10B are conceptual views for explaining the relationship between the light source luminance of the backlight, the light transmittance (opening ratio) of the pixel, and the display luminance in the display area unit.

11A, 11B, and 11C each illustrate a light transmittance (opening ratio) state, a light source luminance state, and a display luminance state in pixels constituting a display area unit for explaining problems in the prior art. It is a figure shown normally.

<Description of the symbols for the main parts of the drawings>

10.Color liquid crystal display 11.Display area

12.Display area unit 13.Liquid crystal material

20. Front panel 21. First substrate

22.Color filter 23.Overcoat layer

24. Transparent first electrode 25. Alignment film

26.Polarizing film 30.Rear panel

31.second substrate 32.switch element

34. Transparent second electrode 35. Alignment film

36.Polarizing film 37.Insulation layer

40.Backlight 41,41R, 41G, 41B.Light Emitting Diode (Light Source)

42.Light source unit 43,43R, 43G, 43B.Photodiode (light sensor)

44 bulkhead 51. casing body

52a. Bottom of case body 52b. Side of case body

53.Outer frame 54.Inner frame

55a, 55b. Spacer 56. Guide member

57.Bracket member 61.Diffusion plate

62.Diffusion Sheet 63.Prism Sheet

64.polarization conversion sheet 65.reflection sheet

70.Backlight control circuit (control unit) 71.Operation circuit

72. Storage device (memory) 80. Light source unit drive circuit (control unit)

81.Backlight 82.Memory Unit (Memory)

83. LED driving circuit 84. Photodiode control circuit

85R, 85G, 85B. Switch element 86. LED driving power supply

90. Liquid crystal display drive circuit 91. Timing controller

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device comprising a liquid crystal display device, a display device having a back light, and a driving method thereof.

In the liquid crystal display device, the liquid crystal material itself does not emit light. Thus, for example, a direct backlight is disposed on the back of the liquid crystal display device. Further, in the color liquid crystal display device, one pixel is composed of three subpixels, for example, a red light emitting subpixel, a green light emitting subpixel, and a blue light emitting subpixel. Then, the liquid crystal cell constituting each pixel or each subpixel is operated as a kind of optical shutter (light valve), that is, the light transmittance (opening ratio) of each pixel or each subpixel. Is controlled and the light transmittance of the illumination light (for example, white light) emitted from the backlight is displayed to display an image.

Conventionally, the backlight illuminates the entire liquid crystal display device uniformly and at a constant brightness. However, the backlight is provided with a plurality of display area units constituting a display area in the liquid crystal display device different from the backlight. Background Art A backlight composed of a plurality of corresponding light source units and having a configuration for changing the distribution of illuminance in a display area unit is known from, for example, Japanese Patent Application Laid-Open No. 2004-258403.

Such a backlight is controlled based on the method described below. Further, based on an input signal input to the drive unit from the outside, a control signal for controlling the light transmittance of the pixel is supplied from the drive unit to each pixel. That is, the maximum luminance of each light source unit constituting the backlight is Y _max , and the maximum value (specifically, 100%, for example) of the light transmittance (opening ratio) of the pixel in the display area unit is Lt _max . do. When each light source unit constituting the backlight has the highest luminance Y _max , the light transmittance (aperture ratio) of each pixel for obtaining display luminance y ₀ of each pixel in the display area unit is Lt _0. Shall be. Then, in this case, the light source luminance Y ₀ of each light source unit constituting the backlight is

_{Y 0 · Lt max = Y max} · Lt 0

It is good to control so as to satisfy. Also, conceptual diagrams of such control are shown in Figs. 10A and 10B. Here, the light source luminance Y ₀ of the light source unit is changed for each frame (called an image display frame for convenience) in the image display of the liquid crystal display device.

As a result of the control of the backlight (also called the division driving of the backlight), an increase in the white level in the liquid crystal display device and an increase in the contrast ratio due to the decrease in the black level can be achieved. The quality of the image display can be improved, and the power consumption of the backlight can be reduced.

[Patent Document 1] Japanese Patent Application Laid-Open No. 2004-258403

An input signal input from the outside corresponding to a maximum value in a plurality of control signals supplied to a plurality of pixels constituting the display area unit is called an internal / maximum input signal (value: x _U-max ). The display area unit of the other display area unit (for convenience, referred to as the (A + 1) th display area unit) and the maximum input signal value (x _U-max ) is a large value (x _H ). adjacent to the unit display region unit (the adjacent) display area unit in a-value of the maximum input signal in [convenience, the a-th display area unit, and the (a + 2) as calling the display area unit of the nth] (x _{U -} Assume _max is a small value (x _L ). That is, the light source luminance of the (A + 1) th light source unit corresponding to the (A + 1) th display area unit is an expensive value (Y _H ), while the Ath and (A + 2) th display area units The light source luminances of the light source units of the A-th and (A + 2) -th light sources corresponding to are low values Y _L. A state of an input signal for controlling the light transmittance (opening ratio) in the pixels constituting such a display area unit is schematically shown in FIG. 11A and a light source luminance state is schematically shown in FIG. 11B. In addition, the light source luminance state shown in FIG. 11B and the display luminance state shown in FIG. 11C showed an ideal state. In practice, the light source luminance of one light source unit is affected by the light source luminance of another light source unit.

By the way, the light transmittance of a liquid crystal cell cannot normally be made into "0" completely. Therefore, even if the input signal is at the minimum value, the light transmittance (opening ratio) of each pixel or each subpixel should not be the minimum value, and light will be dropped from the liquid crystal cell. As a result, in the (A + 1) th display area unit, the input signal corresponding to the control signal to any pixel is the maximum / input signal in the display area unit, and has a large value (x _H ). Assuming that a control signal corresponding to a low value (x _L ) input signal is supplied to the other pixels constituting the (A + 1) th display area unit, the Ath and (A + 2) th display area units are configured. Assume that a control signal corresponding to an input signal having a low value (x _L ) is also supplied to all the pixels (see FIG. 11A). In this case, as shown schematically in Fig. 11C, regardless of whether a control signal corresponding to a low value (x _L ) input signal is supplied to another pixel constituting the (A + 1) th display area unit, In this part, the display luminance becomes higher than the desired display luminance (indicated by the value yy _L in FIG. 11C). As a result, regardless of whether the value of the input signal is the same value (x _L ), the display luminance (the value y _{L in} FIG. 1C) in the pixels constituting the A-th and (A + 2) th display area units is obtained. Difference). When this phenomenon occurs, the black display portion is observed as if it has floated, and a uniform low display luminance state is not obtained, and the quality of the image display is deteriorated.

Accordingly, an object of the present invention is to provide a display apparatus and a driving method thereof which make it possible to make the display luminance state of a dark image display portion as uniform as possible when there is a bright image display portion in the vicinity where the dark image display portion is spread. Is to provide.

In the display device according to the first to third aspects of the present invention, or the display device according to the first to third aspects of the present invention for achieving the above object. The display device,

(a) a display portion comprising a transmissive liquid crystal display device having a display area composed of pixels arranged in a matrix,

(b) a back light for illuminating a rear surface of the display unit, comprising a light source unit individually disposed corresponding to the plurality of display area units constituting the display area;

(c) A display device having a display section and a driving section for driving the backlight on the basis of an input signal from the outside. The driving unit has a control unit for controlling the light emission state of the light source unit corresponding to the display area unit on the basis of the maximum input signal in the display area unit having the maximum value in the input signal corresponding to each display area unit.

In the following description, a plurality of display area units (this display area unit is a kind of virtual one) may be referred to as P × Q display area units, and in this case, the number of light source units is P ×. Q. In addition, an input signal corresponding to one display area unit (the number of input signals is equal to the number of pixels constituting this display area unit, or equal to the number of subpixels constituting this display area unit. In the display area unit, the maximum input signal value may be expressed as "x _{U -max} ". Furthermore, the maximum value in the value (x _{U -max} ) of the maximum input signal in the display area unit (the number of maximum input signals in the display area unit is P × Q) may be expressed as “x _MAX ”. .

In addition, a display area unit whose value (x _{U -max} ) in the display area unit and the maximum input signal is equal to or less than the _first specified value PD _{1 is} referred to as a "low luminance light emission display area unit". The display area unit whose value (x _{U -max} ) of the maximum input signal is the same value as the second specified value (PD ₂ > PD ₁ ), which is greater than the _first specified value (PD ₁ ), or exceeds the second specified value. It is called "high brightness light emission display area unit". In the case where the liquid crystal display device is a color liquid crystal display device, one pixel is composed of three subpixels, for example, a red light emitting subpixel, a green light emitting subpixel, and a blue light emitting subpixel. Therefore, the input signal also includes three sets of input signals, one for the red light emitting pixel, one for the green light emitting pixel, and one for the blue light emitting pixel. The value of the maximum input signal (x _{U -max} ) is the value of the input signal for the maximum red light emitting subpixel, the value of the input signal for the maximum green light emitting subpixel, and the maximum in one display area unit. It indicates the maximum value within the value of the input signal for the blue light emitting subpixel.

In the display device according to the first aspect of the present invention, the control unit includes:

The presence or absence of the low luminance light emitting display area unit,

Investigate whether or not the high luminance light emitting display area unit exists around the low luminance light emitting display area unit,

When the high luminance light emission display area unit exists in the vicinity of the low luminance light emission display area unit, a process of increasing the luminance of the light source unit corresponding to the low luminance light emission display area unit is characterized in that the processing is performed.

In the method of driving the display device according to the first aspect of the present invention,

The controller checks the presence or absence of the low luminance light emitting display area unit.

The control unit checks whether or not the high luminance light emitting display area unit exists in the vicinity of the low luminance light emitting display area unit,

When the high luminance light emission display area unit exists in the vicinity of the low luminance light emission display area unit, the control unit performs a process of increasing the brightness of the light source unit corresponding to the low luminance light emission display area unit.

Moreover, in the display apparatus which concerns on the 2nd form of this invention, a control part is

The ratio (RT ₁ ) of the low luminance light emitting display area unit to all the display area units is obtained.

Investigate whether or not the high luminance light emitting display area unit exists around the low luminance light emitting display area unit,

When the ratio (RT ₁ ) of the low luminance light emitting display area unit is _equal to or greater than a predetermined value (RT ₀ ), while the high luminance light emitting display area unit exists in the vicinity of the low luminance light emitting display area unit, the low luminance light emitting light is emitted. And a process of increasing the brightness of the light source unit corresponding to the display area unit.

In the method of driving the display device according to the second aspect of the present invention,

The ratio (RT ₁ ) of the low luminance light emitting display area unit to the entire display area unit is obtained from the control unit.

The control unit checks whether or not the high luminance light emitting display area unit exists in the vicinity of the low luminance light emitting display area unit,

When the ratio (RT ₁ ) of the low luminance light emission display area unit is _equal to or greater than a predetermined value (RT ₀ ), while the high luminance light emission display area unit exists in the vicinity of the low luminance light emission display area unit, the low luminance light emission occurs A process of increasing the luminance of the light source unit corresponding to the display area unit is performed by the controller.

In the display device according to the third aspect of the present invention, the control unit includes:

The ratio (RT ₁ ) of the low luminance light emitting display area unit to all the display area units is obtained.

Whether or not the high luminance light emitting display area unit exists adjacent to a plurality of consecutive low luminance light emitting display area units;

The ratio (RT ₁ ) of the low luminance light emitting display area unit is _equal to or greater than a predetermined value (RT ₀ ), and there exists a high luminance light emitting display area unit adjacent to a plurality of consecutive low luminance light emitting display area units. And processing to increase the luminance by the light source unit corresponding to the low luminance light emitting display area unit close to the high luminance light emitting display area unit.

Moreover, in the driving method of the display apparatus which concerns on the 3rd aspect of this invention,

The ratio (RT ₁ ) of the low luminance light emitting display area unit to the entire display area unit is obtained from the control unit.

The control unit checks whether or not the high luminance light emitting display area unit exists adjacent to the low luminance light emitting display area unit,

The ratio (RT ₁ ) of the low luminance light emitting display area unit is _equal to or greater than a predetermined value (RT ₀ ), and there exists a high luminance light emitting display area unit adjacent to a plurality of consecutive low luminance light emitting display area units. And a process of increasing the luminance by the light source unit corresponding to the low luminance light emitting display area unit close to the high luminance light emitting display area unit.

In general, the light transmittance (opening ratio) of the pixel (or each subpixel) before correction based on the gamma (gamma) characteristic is determined when the input signal x exceeds a certain value (x _th ). It can be expressed as a linear function of the signal x. However, when the input signal x is below a certain value x _th , the reduction ratio of the light transmittance (opening ratio) is smaller than the reduction ratio of the input signal x. That is, when the input signal x is below a certain value x _th , it deviates from the linear function of the input signal x. In the display device or its driving method according to the first to third aspects of the present invention, the first prescribed value PD ₁ is, for example, a value obtained by normalizing this certain value x _th . Do it. Alternatively, more specifically, the first prescribed value PD ₁ may be any value of 25% or less, preferably 15% or less of the maximum value x _{In -max} of the input signal. Here, as the maximum value x _{In -max} of the input signal, for example, when the gray scale control is 8-bit control, the gray scale control is performed in 2 to ⁸ steps of 0 to 255, but the maximum value of the input signal (x _{In-max). -max} ) is a value corresponding to "255".

In the display device according to the first to third aspects of the present invention including the above-described preferred configuration, or a driving method thereof, the second prescribed value PD ₂ is the maximum input in the display area unit. It can be any value in excess of 25% of the highest value (x _MAX) in the value of the signal (x _{U -max).}

In the display device or the driving method thereof according to the second to third aspects of the present invention including various preferred aspects and configurations described above, the predetermined value RT ₀ depends on the characteristics of the light source. . That is, in the case of using a light source having a small magnification of light, the black display portion is observed to float even when the magnification (area) of the low luminance portion is small, so that the predetermined value RT ₀ needs to be reduced. On the other hand, when using a light source that has a large magnification of light and can brightly illuminate to a distant place, even when the magnification (area) of the low luminance part is large, the black display part is observed to float and becomes difficult, so that a predetermined value ( RT ₀ ) can be increased. Therefore, the predetermined value RT ₀ may be determined by performing various tests and examining the relationship between the magnification (area) of the low luminance portion and the phenomenon observed as if the black display portion floats.

The light transmittance (also called the opening ratio) Lt of the pixel or subpixel, the luminance (display luminance) y of the portion of the display area unit corresponding to the pixel or subpixel, and the luminance (light source luminance) Y of the light source unit It defines as follows.

Y ₁ ... Is the highest luminance, for example, of light source luminance, and may be referred to as light source luminance and first prescribed value hereinafter.

Lt ₁ ... The light transmittance (opening ratio) of the pixel or subpixel in the display area unit is, for example, the maximum value, which may be referred to as light transmittance and the first prescribed value hereinafter.

Lt _{2 When the} light source luminance is the light source luminance first prescribed value Y ₁ , a control signal corresponding to the maximum input signal (value: x _{U -max} ) in the display area unit is supplied to the pixel or sub-pixel. It is the light transmittance (opening ratio) of a pixel or subpixel when assumed, and it may be called light transmittance and a 2nd regulation value below. In addition, 0≤Lt ₂ ≤Lt ₁

y _{2 .. The display} luminance obtained when the light source luminance is the light source luminance and the first prescribed value (Y ₁ ) and the light transmittance (aperture rate) of the pixel or subpixel is the light transmittance and the second prescribed value (Lt ₂ ). Hereinafter, it may be called display luminance second regulation value.

Y _{2 Assuming} that a control signal corresponding to the maximum input signal (value: x _{U -max} ) in the display area unit has been supplied to the pixel or subpixel, and the light transmittance of the pixel or subpixel at this time The light source luminance of the light source unit for setting the luminance of the pixel or subpixel to be the display luminance and the second regulatory value y ₂ when it is assumed that the (opening ratio) is corrected to the light transmittance and the first regulatory value Lt ₁ .

However, the light source luminance Y ₂ may be subjected to correction in consideration of the influence of the light source luminance of each light source unit on the light source luminances of other light source units.

In the display device according to the first aspect of the present invention or a driving method thereof (hereinafter, these may be collectively referred to simply as the first aspect of the present invention), a low luminance light emission display area is controlled by a control unit. The presence or absence of a unit is examined, but in this case, if there is even one low luminance light emitting display area unit, it is assumed that there is a low luminance light emitting display area unit. In addition, the control unit checks whether or not the high luminance light emitting display area unit exists around the low luminance light emitting display area unit, but here, the low luminance light emitting display area unit has one low luminance. High luminance light emitting display area in the case where high luminance light emitting display area unit is adjacent to the light emitting display area unit or R consecutive low luminance light emitting display area units (where R is an integer of 2 or more) It means the unit is adjacent. Alternatively, there are R ＇(where R 'is an integer of 1 or more) display area units (referred to as intermediate display area units for convenience) between the low luminance light emitting display area unit and the high luminance light emitting display area unit. I mean the state. In this case, the intermediate display area unit has a value (x _{U -max} ) within the display area unit _exceeding the first prescribed value PD ₁ while being less than the _second specified value PD ₂ . Is a display area unit.

Further, in the first aspect of the present invention, when the high luminance light emitting display area unit exists around the low luminance light emitting display area unit, the luminance of the light source unit corresponding to the low luminance light emitting display area unit is increased. Although the process of making it make it carry out, specifically, the following processes are implemented, for example. That is, assuming that a control signal corresponding to the maximum input signal in the display area unit (where the value ( _x＇U-max ) exceeds (x _MAX )) is supplied to the pixel or subpixel, Assuming that the light transmittance (opening ratio) of the pixel or subpixel at this time is corrected to the light transmittance · 1 prescribed value Lt ₁ , a light source for setting the luminance of the pixel or subpixel to be the display luminance and the second prescribed value y ₂ . The processing is performed such that the light source luminance (may be denoted as Y ₂ kHz) of the unit is obtained. This processing may be performed on the light source units corresponding to all the low luminance light emitting display area units. It is also assumed that a control signal corresponding to the maximum input signal (value: x _{U -max} ) in the display area unit has been supplied to the pixel or subpixel, and the light transmittance (opening ratio) of the pixel or subpixel at this time is light. Assuming that the transmittance and the first regulation value Lt ₁ are corrected, the light source luminance of the light source unit for setting the luminance of the pixel or subpixel to the display luminance and the second regulation value y ₂ is the light source luminance (Y ₂ ＇). For all of the light source units that do not reach, the processing in which the light source luminance becomes Y ₂ kW may be performed. In other light source units, it is assumed that a control signal corresponding to the maximum input signal (value: x _{U -max} ) in the display area unit is supplied to the pixel or sub-pixel, and at this time, the pixel or sub-pixel Assuming that the light transmittance (aperture rate) of the light source unit is corrected to the light transmittance · 1 prescribed value (Lt ₁ ), the light source luminance (Y) of the light source unit for setting the luminance of the pixel or subpixel to the display luminance / second prescribed value (y ₂ ) _What is necessary is just to implement the process as ₂ ) is obtained.

In the display device related to the second aspect of the present invention or a driving method thereof (hereinafter, these may be collectively referred to simply as the second aspect of the present invention), a high luminance light emitting display unit is provided by a control unit. Is examined in the periphery of the low luminance light emitting display area unit, but here, the &quot; periphery &quot; of the low luminance light emitting display area unit is a high luminance light emitting display area in one low luminance light emitting display area unit. The case where the units are adjacent to each other or that the high luminance light emitting display area unit is adjacent to one end of consecutive R low luminance light emitting display area units (where R is an integer of 2 or more). Alternatively, it means a state in which R ＇(where R 'is an integer equal to or greater than 1) intermediate display area units exist between the low luminance light emitting display area unit and the high luminance light emitting display area unit. In addition, when the ratio RT ₁ of the low luminance light emission display area unit is _equal to or greater than a predetermined value RT ₀ , the high luminance light emission display area unit is present in the vicinity of the low luminance light emission display area unit. Although the process of increasing the brightness of the light source unit corresponding to the light emission and display area unit is performed, specifically, the same process as described in the first aspect of the present invention may be performed. In the second aspect of the present invention, when the ratio RT ₁ of the obtained low luminance light emission display area unit to all display area units is _equal to or greater than a predetermined value RT ₀ , the low luminance light emission display area Since a process of increasing the brightness of the light source unit corresponding to the unit is performed, more natural image display can be obtained.

In the display device related to the third aspect of the present invention or a driving method thereof (hereinafter, these may be collectively referred to simply as the third aspect of the present invention), a high brightness light emitting display unit is provided by a control unit. A process of increasing the luminance by the light source unit corresponding to the low luminance light emitting display area unit close to is performed. Specifically, R consecutive low-luminance light-emitting display area units (where R is an integer of 2 or more) based on the position of the high-luminance light-emitting display area unit are the first low-luminance light-emitting display area units. When the second low luminance light emitting display unit is used as the second (R-1) th low luminance light emitting display unit, and the Rth low luminance light emitting display unit is used. In the light source unit corresponding to the first low luminance light emitting display area unit (r = 1, 2 ... R), the maximum input signal in the display area unit (value: x ” _U-max (r)) that the control signal is supplied to the pixel or sub-pixel is assumed which corresponds to and, in addition, when this time the pixels or the light transmittance (aperture ratio) of the sub-pixels of the assumption that the correction to the light transmittance · first specified value (Lt _1), pixel or Light source light of the light source unit for setting the luminance of the subpixel to the display luminance and the second prescribed value (y ₂ ) Degree and the process as described is obtained (is sometimes denoted as Y ₂ (r) "). Here, the value (x ” _U-max (r)) of the maximum input signal in the display area unit is

x ” _U-max (r) = β ₁ ^rx _MAX (Where 0 <β ₁ <1)

or,

_{x "U-max (r)} = (1-β 2 · r) x MAX (0 <β ₂ <1)

If you are satisfied. In the third aspect of the present invention, when the ratio RT ₁ of the obtained low luminance light emitting display area unit to the all display area units is _equal to or greater than a predetermined value RT ₀ , the low luminance light emitting display area is obtained. Since a process of incrementally increasing the brightness of the light source unit corresponding to the unit is performed, a more natural image display can be obtained.

In the first aspect of the present invention, when the high luminance light emission display area unit does not exist in the vicinity of the low luminance light emission display area unit, the following processing is performed in all the light source units, for example. In the second aspect of the present invention, when the ratio RT ₁ of the low luminance light emission display area unit is less than a predetermined value RT ₀ or the high luminance light emission display area unit is low luminance light emission / display. Even if it does not exist in the vicinity of the area unit, the following processing is performed in all the light source units, for example. Further, in the third aspect of the present invention, when the ratio RT ₁ of the low luminance light emission display area unit is less than a predetermined value RT ₀ , or the high luminance light emission display area unit is low luminance light emission / display. For example, the following processing is performed in all the light source units even when they are not adjacent to the area unit or when there are a plurality of low luminance light emitting display areas, and they are not continuous. That is, assuming that a control signal corresponding to the maximum input signal (value: x _U-max ) in the display area unit is supplied to the pixel or subpixel, and the light transmittance (opening ratio) of the pixel or subpixel at this time is light. Assuming that the transmittance and the first regulatory value Lt ₁ are corrected, the same processing as the light source luminance Y ₂ of the light source unit for obtaining the luminance of the pixel or subpixel as the display luminance and the second regulatory value y ₂ is obtained. Is carried out.

In the display device which concerns on the 1st-3rd form of this invention including the preferable form and structure which were demonstrated above, or its driving method (henceforth these may be called generically only this invention), One light source unit is surrounded by four light source units, or is surrounded by three light source units and one side of the case body (to be described later), or two of the two light source units and the case body. It is surrounded by the side of the dog. In the case where the high luminance light emitting display area unit exists in the vicinity of the low luminance light emitting display area unit or is adjacent to the low luminance light emitting display area unit, According to at least one of the directions (vertical, horizontal and inclined), a high luminance light emitting display unit may exist or be adjacent to each other.

In the present invention, a light emitting diode (LED) may be used as a light source of the light source unit constituting the backlight, or a cold cathode linear fluorescent lamp, an electroluminescence (EL) device, Cold cathode field emission devices (FEDs), plasma displays, and ordinary lamps may also be mentioned. When the light source is configured from a light emitting diode, for example, a red light emitting diode emitting red light having a wavelength of 640 nm, for example, a green light emitting diode emitting green light having a wavelength of 530 nm, and a blue light emitting diode emitting blue light having a wavelength of 450 nm, for example. The white light can be obtained by forming a pair of white light, and white light can also be obtained by light emission of a white light emitting diode (for example, a light emitting diode which emits white light by combining ultraviolet or blue light emitting diodes with phosphor particles). You may further be provided with the light emitting diode which light-emits the 4th color and 5th color ... other than red, green, and blue.

When the light source is constituted by light emitting diodes, a plurality of red light emitting diodes emitting red light, a plurality of green light emitting diodes emitting green light, and a plurality of blue light emitting diodes emitting blue light are arranged and arranged in a case body. . More specifically, (1 red light emitting diode, 1 green light emitting diode, 1 blue light emitting diode), (1 red light emitting diode, 2 green light emitting diodes, 1 blue light emitting diode), (2 red light emitting diodes) Diode, two green light emitting diodes, one blue light emitting diode), and the like. At least one light emitting diode unit is provided in one light source unit.

The light emitting diode may have a so-called face up structure or may have a flip chip structure. That is, the light emitting diode may be composed of a substrate and a light emitting layer formed on the substrate, and may be a structure in which light is emitted from the light emitting layer to the outside, or may be a structure in which light from the light emitting layer is emitted to the outside through the substrate. More specifically, the light emitting diode (LED) includes, for example, a first clad layer and a first clad layer formed of a compound semiconductor layer having a first conductivity type (for example, n type) formed on a substrate. A first electrode having a laminated structure of an active layer formed on the second clad layer and a compound semiconductor layer having a second conductivity type (for example, p-type) formed on the active layer, and electrically connected to the first clad layer; A second electrode electrically connected to the second cladding layer is provided. The layer constituting the light emitting diode may be made of a known compound semiconductor material depending on the light emission wavelength.

In the present invention, it is preferable that an optical sensor for measuring the light emission state of the light source (specifically, for example, the brightness of the light source, the chromaticity of the light source, or the brightness and chromaticity of the light source) is disposed. Although the minimum number of photosensors may be sufficient, it is preferable to set it as the structure by which one set of photosensors are arrange | positioned in one light source unit from a viewpoint of reliably measuring the light emission state of each light source unit. As an optical sensor, a well-known photodiode and a CCD device are mentioned. When the light source is constituted of, for example, a red light emitting diode, a green light emitting diode, and a blue light emitting diode as a pair, the light emission state of the light source measured by the optical sensor is the luminance and chromaticity of the light source. In this case, a set of optical sensors may be used for the photodiode with a red filter to measure the light intensity of the red light, the photodiode with a green filter to measure the light intensity of the green light, and the light intensity of the blue light. It can be configured as a photodiode equipped with a blue filter in order to measure.

The drive unit including the control unit includes, for example, a control circuit composed of a pulse width modulation (PWM) signal generation circuit, a duty ratio control circuit, a light emitting diode (LED) drive circuit, a calculation circuit, a memory device (memory), and the like (back as a control unit). And a liquid crystal display device driving circuit composed of known circuits such as a light control circuit and a light source unit driving circuit) and a timing controller.

The backlight can also be configured to include a group of optical functional sheets such as a diffusion plate, a diffusion sheet, a prism sheet, and a polarization conversion sheet, and a reflection sheet.

Control of the luminance (display luminance) of the pixel and the luminance (light source luminance) of the light source unit is performed for each image display frame. The number of image information (every second image) sent to the drive unit as an electric signal for one second is the frame frequency, and the inverse of the frame frequency is the frame time (unit: second).

The transmissive liquid crystal display device is made of, for example, a front panel having a transparent first electrode, a rear panel having a transparent second electrode, and a liquid crystal material disposed between the front panel and the rear panel.

More specifically, the front panel is, for example, a transparent first electrode (also called a common electrode) provided on an inner surface of a first substrate made of a glass substrate or a silicon substrate and the first substrate, for example, ITO And the polarizing film provided on the outer surface of the first substrate. In the transmissive color liquid crystal display device, a color filter coated with an overcoat layer made of an acrylic resin or an epoxy resin is provided on the inner surface of the first substrate. Examples of the arrangement pattern of the color filter include a delta array, a stripe array, a diagonal array, and a recreation array. And the front panel further has the structure in which the transparent 1st electrode was formed on the overcoat layer. In addition, an alignment film is formed on the transparent first electrode. On the other hand, as for the rear panel, conduction / non-conduction is controlled by the switch element and the switch element which were formed in the inner surface of the 2nd board | substrate which consists of a glass substrate and a silicon substrate, and a 2nd board | substrate, for example. It consists of a transparent 2nd electrode (also called a pixel electrode and consists of ITO, for example), and the polarizing film provided in the outer surface of a 2nd board | substrate. An alignment film is formed on the entire surface including the transparent second electrode. Various members and liquid crystal materials constituting the liquid crystal display device including these transmissive color liquid crystal display devices can be composed of known members and materials. Examples of the switch element include three-terminal elements such as MOS type FETs and thin film transistors (TFTs) formed on a single crystal silicon semiconductor substrate, and two-terminal elements such as MIM elements, varistor elements, and diodes.

A region including a liquid crystal cell that meets in an overlapping region of the transparent first electrode and the transparent second electrode corresponds to one pixel (pixel) or one subpixel (subpixel). In the transmissive color liquid crystal display device, the red light emitting subpixel (subpixel [R]) constituting each pixel (pixel) is composed of a combination of a relevant region and a color filter transmitting red color, and green The light emitting sub-pixel (subpixel [G]) is composed of a combination of a relevant region and a color filter that transmits green, and the blue light emitting subpixel (subpixel [B]) transmits the relevant region and blue. It consists of a combination with a color filter. The arrangement pattern of the subpixel [R], the subpixel [G], and the subpixel [B] corresponds to the arrangement pattern of the color filter mentioned above. In addition, the pixel is not limited to the structure which consists of three sets of subpixels of a red light emitting subpixel, a green light emitting subpixel, and a blue light emitting subpixel as a set, for example, to these 3 subpixels, or one or more 1 trillion plus subpixels (e.g., 1 trillion plus subpixels emitting white to improve brightness, 1 trillion plus subpixels emitting complementary colors to expand color reproduction, In order to expand the color reproduction range, a pair of subpixels emitting yellow and cyan may be added).

As a value when denote the number of elements (pixels) arranged in a matrix M ₀ × N ₀ to _{(M 0, N 0),} (M 0, N 0), Specifically, VGA (640,480), S -VGA (800,600), XGA (1024,768), APRC (1152,900), S-X GA (1280,1024), U-XGA (1600,1200), HD-TV (1920,1080), Q- Although the number of resolutions for image display, such as XGA (2048, 1536), (1920, 1035), (720, 480), (1280, 960), can be illustrated, it is not limited to these values. Further, as a relationship between the value of the value of the (M _0, N ₀₎ and (P, Q), but not limited to, it can be exemplified in Table 1 below. As the number of pixels constituting one display area unit, 20x20 to 320x240, preferably 50x50 to 200x200 can be exemplified. The number of pixels in the display area unit may be constant or may differ.

Hereinafter, although the display apparatus of this invention is demonstrated based on an Example with reference to drawings, Prior to that, the outline | summary of the display part and backlight which consist of a transmissive color liquid crystal display apparatus suitable for use in an Example is shown in FIG. 5, 6A, 6B, and 7 will be described.

As shown the schematic diagram in Figure 4, a color liquid crystal display device 10 of a transmission type corresponding to the display portion, one M ₀ depending on the direction of the first and N ₀ of, in total, depending on the direction of the 2 M ₀ × N ₀ The display area 11 has four pixels arranged in a matrix. It is assumed here that the display area 11 is divided into P × Q virtual display area units 12. Each display area unit 12 is composed of a plurality of pixels. Specifically, for example, when the resolution for image display satisfies the HD-TV standard, and the number M ₀ × N ₀ of the pixels (pixels) arranged in a matrix form is expressed as (M ₀ , N ₀ ), For example, (1920, 1080). In addition, the display region 11 (indicated by a dashed-dotted line in FIG. 4) composed of pixels arranged in a matrix form is arranged in the P × Q virtual display region units 12 (shown by dotted lines). It is divided. The value of (P, Q) is (19, 12), for example. However, for the sake of simplicity, the number of display area units 12 (and the light source unit 42 described later) in FIG. 4 is different from this value. Each display area unit 12 is composed of a plurality of M × N pixels, and the number of pixels constituting one display area unit 12 is about 10,000, for example. Each pixel is comprised by one set of several subpixel which light-emits different color. More specifically, each pixel includes three subpixels of a red light emitting subpixel (subpixel [R]), a green light emitting subpixel (subpixel [G]), and a blue light emitting subpixel (subpixel [B]). Subpixels). This transmissive color liquid crystal display device 10 is linearly driven. More specifically, the color liquid crystal display device 10 has a scan electrode (which extends along the first direction) and a data electrode (which extends along the second direction) that intersect in a matrix form. A scan signal is input to select and scan a scan electrode, and an image is displayed based on the data signal (a signal based on a control signal) input to the data electrode to form one screen.

As shown in FIG. 7, the color liquid crystal display device 10 is a front panel 20 having a transparent first electrode 24 and a rear panel having a transparent second electrode 34. 30 and the liquid crystal material 13 disposed between the front panel 20 and the rear panel 30.

The front panel 20 is comprised from the 1st board | substrate 21 which consists of a glass substrate, and the polarizing film 26 provided in the outer surface of the 1st board | substrate 21, for example. The inner surface of the first substrate 21 is provided with a color filter 22 coated with an overcoat layer 23 made of an acrylic resin or an epoxy resin, and a transparent first electrode (common electrode) on the overcoat layer 23. Also referred to as, for example, ITO (24) is formed, and the alignment film 25 is formed on the transparent first electrode 24. On the other hand, the rear panel 30 is more specifically, for example, a second substrate 31 made of a glass substrate and a switch element formed on the inner surface of the second substrate 31 (specifically, A thin film transistor (TFT) 32, a transparent second electrode (also referred to as a pixel electrode, made of, for example, ITO) 34 whose conduction / non-conduction is controlled by the switch element 32, and the second The polarizing film 36 provided on the outer surface of the board | substrate 31 is comprised. An alignment film 35 is formed on the entire surface including the transparent second electrode 34. The front panel 20 and the rear panel 30 are joined to each other through a sealing material (not shown) at their outer periphery. In addition, the switch element 32 is not limited to TFT, For example, it can also be comprised with a MIM element. In the drawing, reference numeral 37 is an insulating layer provided between the switch element 32 and the switch element 32.

Since the various members and liquid crystal material which comprise such a transmissive color liquid crystal display device can be comprised by a well-known member and material, detailed description is abbreviate | omitted.

The backlight (direct-surface planar light source device) 40 is composed of P × Q light source units 42 individually disposed corresponding to the P × Q virtual display area units 12, and each light source unit 42 illuminates the display area unit 12 corresponding to the light source unit 42 from the back side. And the light source with which the light source unit 42 is equipped is controlled individually. In addition, although the backlight 40 is located under the color liquid crystal display 10, in FIG. 4, the color liquid crystal display 10 and the backlight 40 were displayed separately. The arrangement and arrangement of light emitting diodes and the like in the backlight 40 are schematically shown in FIG. 6A, and a schematic partial cross-sectional view of a display device including the color liquid crystal display device 10 and the backlight 40 is shown in FIG. 6B. Shown in The light source is comprised of the light emitting diode 41 driven based on a pulse width modulation (PWM) control system.

As shown in the schematic partial cross-sectional view of the display device in FIG. 6B, the backlight 40 is composed of a case body 51 having an outer frame 53 and an inner frame 54. The end portions of the transmissive color liquid crystal display device 10 are held by the outer frame 53 and the inner frame 54 so as to be interposed between the spacers 55A and 55B. In addition, a guide member 56 is disposed between the outer frame 53 and the inner frame 54, and the color liquid crystal display device 10 interposed between the outer frame 53 and the inner frame 54. ) Is a structure that does not shift. The diffusion plate 61 is attached to the inner frame 54 through the spacer 55C and the bracket member 57 in the upper portion of the case body 51. Moreover, on the diffuser plate 61, the optical function sheet group called the diffusion sheet 62, the prism sheet 63, and the polarization conversion sheet 64 is laminated | stacked.

The reflection sheet 65 is provided in the lower part of the case body 51. Here, the reflecting sheet 65 is disposed so that the reflecting surface thereof faces the diffuser plate 61, and is attached to the bottom surface 52A of the case body 51 via a mounting member (not shown). The reflective sheet 56 can be formed, for example, of a silver reflective film having a structure in which a silver reflective film, a low refractive index film, and a high refractive index film are laminated in this order on a sheet substrate. The reflective sheet 65 includes light emitted from the plurality of light emitting diodes 41 (light sources 41), side surfaces 52B of the case body 51, or in some cases, partition walls 44 shown in FIG. 6A. Reflects the reflected light. In this way, a plurality of red light emitting diodes 41R (light sources 41R) that emit red light, a plurality of green light emitting diodes 41G (light sources 41G) that emit green light, and a plurality of blue light emitting diodes 41B (light emitting blue) ( Red light, green light and blue light emitted from the light source 41B are mixed colors, and white light having high color purity can be obtained as illumination light. This illumination light passes through a group of optical function sheets called a diffuser plate 61, a diffusion sheet 62, a prism sheet 63, and a polarization conversion sheet 64, and irradiates the color liquid crystal display device 10 from the back side. do. The light source unit 42 and the light source unit 42 constituting the backlight 40 are divided into partitions 44. The partition 44 is attached to the bottom face 52A of the case body 51 via a mounting member (not shown).

In the vicinity of the bottom surface 52A of the case body 51, photodiodes 43R, 43G and 43B which are optical sensors are arranged. In addition, the photodiode 43R is a photodiode equipped with a red filter for measuring the light intensity of red light, and the photodiode 43G is a photodiode with a green filter for measuring the light intensity of green light. The photodiode 43B is a photodiode equipped with a blue filter in order to measure the light intensity of blue light. Here, one set of light sensors (photo diodes 43R, 43G, 43B) is arranged in one light source unit 42. The light emission states of the light sources 41R, 41G, 41B measured by the photodiodes 43R, 43G, 43B as optical sensors are the luminance and chromaticity of the light emitting diodes 41R, 41G, 41B.

The arrangement state of the light emitting diodes 41R, 41G, 41B is, for example, a red light emitting diode 41R that emits red (e.g., a wavelength of 640 nm), and green that emits green (e.g., a wavelength of 530nm). A plurality of light emitting diode units including a light emitting diode 41G and a blue light emitting diode 41B that emits blue (for example, a wavelength of 450 nm) as a pair can be arranged in a horizontal direction and in a vertical direction. In this case, one light emitting diode unit is arranged in one light source unit 42.

As shown in Figs. 4 and 5, the driving unit for driving the backlight 40 and the color liquid crystal display device 10 based on an input signal from the outside (display circuit) is based on the pulse width modulation control method. A backlight control circuit 70 and a light source unit driving circuit for performing on / off control of the red light emitting diode 41R, the green light emitting diode 41G, and the blue light emitting diode 41B constituting the backlight 40; 80) (corresponding to the control section) and the liquid crystal display device driver circuit 90. As shown in FIG. The backlight control circuit 70 is composed of an operation circuit 71 and a memory device (memory) 72. The light source unit 42 corresponding to the display area unit 12 is based on the maximum and the input signal in the display area unit having the maximum value (x _{U -max} ) among the input signals corresponding to each display area unit 12. Control the light emission state. On the other hand, the light source unit driving circuit 80 is composed of a computing circuit 81, a memory device (memory) 82, an LED driving circuit 83, a photodiode control circuit 84, and a switch element 85R, 85G. 85B), and a light emitting diode driving power supply (constant current source) 86. Such a circuit or the like constituting the backlight control circuit 70 and the light source unit driving circuit 80 can be a known circuit or the like. On the other hand, the liquid crystal display drive circuit 90 for driving the color liquid crystal display device 10 is configured by a known circuit called the timing controller 91. The color liquid crystal display device 10 is equipped with a gate driver, a source driver, and the like (these are not shown) for driving the switch element 32 formed of TFTs constituting the liquid crystal cell. The light emitting states of the light emitting diodes 41R, 41G, 41B in any image display frame are measured by the photodiodes 43R, 43G, 43B, and the output from the photodiodes 43R, 43G, 43B is a photodiode. Inputted to the control circuit 84, the photodiode control circuit 84 and the calculation circuit 81 regard the light emitting diodes 41R, 41G and 41B as data (signals), for example, as luminance and chromaticity, and The data to be sent is sent to the LED driving circuit 83, and a feedback mechanism is formed in which the light emitting states of the light emitting diodes 41R, 41G, and 41B are controlled in the next image display frame. Downstream of the light emitting diodes 41R, 41G, and 41B, resistors r _R , r _G , and R _B for current detection are inserted in series with the light emitting diodes 41R, 41G, 41B, and the resistor r Under the control of the LED driving circuit 83, the current flowing through _R , r _G , r _B is converted into a voltage, and the voltage drop in the resistors r _R , r _G , r _B becomes a predetermined value. The operation of the LED driving power supply 86 is controlled. Here, in Fig. 5, the light emitting diode driving power supply (constant current source) 86 is described as one, but in reality, the light emitting diode driving power supply 86 for driving each of the light emitting diodes 41R, 41G, and 41B. This is arranged.

A display area composed of pixels arranged in a matrix form is divided into P × Q display area units. However, when this state is expressed in “rows” and “columns”, the display area is divided into Q row × P column display area units. I can speak. In addition, the display area unit 12 is composed of a plurality of pixels (M × N). However, when this state is expressed by “row” and “column”, it can be said that the display area unit 12 is composed of pixels of N rows × M columns. . Further, the display area unit is arranged in a matrix and is located in the qth row and the pth column (where q = 1, 2, ..., Q and p = 1, 2, ..., P). , The light source unit is denoted by the display area unit 12 ( _{q, p} ) and the light source unit 42 ( _{q, p} ) _, respectively, and the display area unit 12 ( _{q, p} ) or the light source unit 42. the elements, items related to the _{(q, p),} the subscript "(q, p)" or - in some cases will add a "(q, p)". Here, the red light emitting subpixels (subpixel [R]), the green light emitting subpixels (subpixel [G]) and the blue light emitting subpixels (subpixel [B]) are collectively collected as "subpixels [R, G, B] ”and the subpixels [R, G, B] for the control of the operation of the subpixels [R, G, B] (specifically, the control of the light transmittance (opening ratio), for example). The red light emission control signal, the green light emission control signal, and the blue light emission control signal which are input to the data may be collectively referred to as "control signals [R, G, B]", and the sub-pixels [R, G forming the display area unit may be referred to. , B], the red light emitting pixel input signal, the green light emitting pixel input signal and the blue light emitting pixel input signal which are input from the outside to the driving unit are collectively collected and called "input signal [R, G, B]". There is a case.

Each pixel has three subpixels (subpixels) of a subpixel [R] (red light emitting subpixel), a subpixel [G] (green light emitting subpixel), and a subpixel [B] (blue light emitting subpixel). Although it is configured as a group, in the following description of the embodiments, the control (gradation control) of the luminance of each of the subpixels [R, G, B] is set as 8-bit control, and is performed in ^2-8 steps of 0 to 255. do. Therefore, the input signals [R, G,] input to the liquid crystal display drive circuit 90 to drive each of the sub-pixels [R, G, B] in each pixel constituting each display area unit 12. Each of the value of B] (x _R , x _G , x _B ) takes the values of 2 ⁸ steps. In addition, the values of the pulse width modulation output signals S _R and S _G for controlling the light emission time of the red light emitting diode 41R, the green light emitting diode 41G, and the blue light emitting diode 41B constituting each light source unit, respectively. , S _B ) also takes a value from 2 to ^{8 in} the range 0 to 255. However, the present invention is not limited to this, and for example, 10-bit control may be performed in ^2-10 steps of 0 to 1023. In this case, the expression of 8-bit numerical value is increased by 4 times. It is good.

To each of the pixels, a control signal for controlling each light transmittance Lt of the pixel is supplied from the driver. Specifically, a control signal [R, G, B] for controlling the light transmittance Lt of each of the subpixels [R, G, B] is provided in each of the subpixels [R, G, B]. It is supplied from the drive circuit 90. That is, in the liquid crystal display drive circuit 90, control signals [R, G, B] are generated from the input signals [R, G, B] input, and the control signals [R, G, B] are negative. It is supplied (output) to the pixels [R, G, B]. In addition, since the light source luminance Y ₂ of the light source unit 42 is changed for each image display frame, the control signals [R, G, B] basically change the values of the input signals [R, G, B]. The value multiplied by 2.2 has a value that is corrected (compensated) based on the change in the light source luminance Y ₂ . Then, the control signals [R, G, B] are known from the timing controller 91 constituting the liquid crystal display device driver circuit 90 to the gate driver and the source driver of the color liquid crystal display device 10. And the switch element 32 constituting each subpixel is driven based on the control signals [R, G, B], and the transparent first electrode 24 and the transparent second electrode 34 constituting the liquid crystal cell are driven. By applying a desired voltage to), the light transmittance (opening ratio) Lt of each subpixel is controlled. Here, the larger the value of the control signals [R, G, B], the higher the light transmittance (the aperture ratio of the subpixels) Lt of the subpixels [R, G, B], and the subpixels [R, G, B]. ] Luminance (display luminance y) becomes expensive. That is, the image (usually a kind and point shape) comprised by the light which passes through subpixels [R, G, B] is bright.

Control of the display luminance y and the light source luminance Y ₂ is performed for each image display frame, for each display area unit, and for each light source unit in the image display of the color liquid crystal display device 10. In addition, the operation of the color liquid crystal display device 10 and the operation of the backlight 40 in one image display frame are synchronized.

Embodiment 1 relates to a display device and a driving method thereof according to the first aspect of the present invention. In Embodiment 1, in the backlight control circuit 70 and the light source unit driving circuit 80 corresponding to the control unit, the presence or absence of the low luminance light emitting display area unit is checked, while the high luminance light emitting display area is checked. It is checked whether or not the unit exists around the low luminance light emitting display area unit, and when the high luminance light emitting display area unit exists around the low luminance light emitting display area unit, the low luminance light emitting display area unit The process of increasing the brightness of the light source unit corresponding to the above is performed.

In Embodiment 1 or Embodiments 2 to 3 described later, the first prescribed value PD1 is any value of 25% or less of the maximum value x _{In -max} of the input signal. The second prescribed value PD2 is a value of 100% of the maximum value x _{MAX in the} display area unit / maximum input signal value x _{U -max} , that is, the maximum value x _MAX itself. . In addition, since the gray scale control is performed in 2 to ⁸ steps of 0 to 255, the maximum value x _{In -max} of the input signal is a value corresponding to "255".

Hereinafter, the driving method of the display device in Example 1 is demonstrated with reference to FIG. 1, FIG. 3, FIG. 4, and FIG.

[Step-100]

The input signals [R, G, B] and the clock signal CLK for one image display frame sent from a known display circuit such as a scan converter are input to the backlight control circuit 70 and the liquid crystal display device driver circuit 90. (See FIG. 4). The input signals [R, G, B] are output signals from the imaging tube, for example, when the amount of input light to the imaging tube is y _in . ) Is an input signal which is also input to the liquid crystal display driver circuit 90 to control, and can be expressed as a function of 0.45 times the input light quantity y _in . The value (x _R , x _G , x _B ) of the input signal [R, G, B] for one image display frame input to the backlight control circuit 70 constitutes the backlight control circuit 70. The memory device (memory) 72 is stored once. The liquid crystal display driver circuit 90 also has a value (x _R , x _G , x _B ) of the input signals [R, G, B] for one image display frame input to the liquid crystal display driver circuit 90. It is stored once in the memory | storage device (not shown) which comprises this.

[Step -110]

Next, in the arithmetic circuit 71 constituting the backlight control circuit 70, the value of the input signals [R, G, B] stored in the storage device 72 is read out, and the (p, q) In the display area unit 12 _{(q, p)} of the [th, first, p = 1, q = 1], the (p, q) second display area unit 12 _{(q, p)} is The value of the input signals [R, G, B] _{(q, p)} for driving the subpixels [R, G, B] _{(q, p)} in all the pixels constituting _, x _{R- (q, p),} The calculation circuit 71 obtains the value x _{U -max (q, p)} of the maximum input signal in the display area unit which is the maximum value in x _{G- (q, p)} and x _{B- (q, p)} . The storage unit 72 stores the value x _{U -max (q, p)} of the internal / maximum input signal in the display area unit. This step is performed for all of m = 1, 2, ..., M, n = 1, 2, ..., N, that is, MxN pixels.

For example, x _{R- (q, p)} is a value corresponding to "110", x _{G- (q, p)} is a value corresponding to "250", and x _{B- (q, p)} is " In the case of a value corresponding to "50", x _{U -max (q, p)} is a value corresponding to "250".

This operation is repeated from (p, q) = (1, 1) to (P, Q), and the value of the maximum input signal in the display area unit in all the display area units 12 _{(q, p)} . x _{U -max (q, p)} is stored in the storage device 72.

Similarly, in the arithmetic circuit 71 _, the presence or absence of the low luminance light emitting display area unit whose value x _{U-max (q, p)} of the maximum input signal in the display area unit is equal to or less than the first specified value PD ₁ is determined. If there is even one low luminance light emitting display area unit, the position (p, q) is stored in the storage device 72, and the low luminance light emitting display area unit present flag is already reset. Change from the initial value "0" to "1". Further, in the arithmetic circuit 71, a display unit in a region, the maximum value of the input signal _{x U -max (q, p)} , the value of the high luminance light emission over a predetermined value or a value of the second predetermined value, such as 2 PD ₂ of Investigate whether the display area unit exists in the vicinity of the low luminance light emitting display area unit, and if such a high luminance light emitting display area unit exists, the positions p and q are stored in the storage device 72. Then, the high luminance light emission display area unit present flag is changed from the initial value "0" already reset.

In addition, in Example 1, the high luminance light emission display area unit is adjacent to each other in the direction of the low luminance light emission display area unit (near each other). In this case, it is assumed that a high luminance light emitting display area unit exists around the low luminance light emitting display area unit.

Light transmittance (opening ratio) in the pixels constituting the display area unit when the low luminance light emission display area unit present flag is "1" and the high luminance light emission display area unit present flag is "1". 1A schematically shows an input signal state for controlling?, And FIG. 1B schematically shows a light source luminance (light source luminance 1) state in this state. In addition, the value (x _{U -max} ) of the maximum input signal in the display area unit of the high luminance light emission display area unit is represented by (x _H ), and the maximum input signal in the display area unit of the low luminance light emission display area unit is indicated. The value (x _{U -max} ) is represented by (x _L ). In this state, the light source luminance 1 of the light source unit corresponding to the high luminance light emitting display area unit is a high value (Y _H ), and the light source luminance 1 of the light source unit corresponding to the low luminance light emitting display area unit. Is a low value Y _L. The state of the light source luminance 1 shown in FIG. 1B and the light source luminances (light source luminances 1 and 2) and display luminance states shown in FIGS. 1C, 1D, 2B, 2C, and 2D described later showed an ideal state. . In practice, the light source luminance of one light source unit is affected by the light source luminance of another light source unit. 1 or 2 to be described later, the high luminance light emitting display area unit and the low luminance light emitting display area unit are referred to as a high luminance display area unit and a low luminance display area unit, and a light source unit corresponding to these is shown. High brightness light source units and low brightness light source units are indicated.

[Step -120]

Next, when the low luminance light emission display area unit present flag is "1" and the high luminance light emission display area unit present flag is "1", the light source unit corresponding to the low luminance light emission display area unit Although the process which increases a brightness | luminance is performed, the following process is specifically implemented. Specifically, specifically, the control signal [R, corresponding to the maximum input signal in the display area unit (where the value x ＇ _U-max is a value exceeding x _MAX and is the same in the second embodiment described later). Assuming that G and B are supplied to the subpixels [R, G, B], the light transmittance (opening ratio) of the subpixels [R, G, B] at this time is the light transmittance and the first prescribed value (Lt ₁ ). Is assumed to have been corrected, the light source luminance Y of the light source unit for setting the luminance of the subpixels [R, G, B] to be the display luminance and the second prescribed value (y ₂ and represented by y _L 는 in FIG. 1D). ₂ iv) (indicated by Y _L 'in FIG. 1C) is performed. In other words, the light source luminance of the light source unit is increased or decreased under the control of the light source unit driving circuit 80 _{(q, p)} .

In the first embodiment, this processing is performed on the light source units corresponding to all the low luminance light emitting display area units. It is also assumed that the control signals [R, G, B] corresponding to the maximum and maximum input signals (value: x _U-max ) in the display area unit are supplied to the subpixels [R, G, B]. Assuming that the light transmittance (opening ratio) of the subpixels [R, G, B] is corrected to the light transmittance, the first prescribed value Lt ₁ , the luminance of the subpixels [R, G, B] is displayed. the predetermined value (y _2), the light source luminance of the light source unit for a 'with respect to all of the light source units that are short of, the light source luminance (light source luminance y ₂ (y _2), and the process such that a). In the other light source units, control signals [R, G, B] corresponding to the maximum input signal (value: x _{U -max} ) in the display area unit are supplied to the subpixels [R, G, B]. In addition, assuming that the light transmittance (opening ratio) of the subpixels [R, G, B] at this time is corrected to the light transmittance and the first prescribed value (Lt ₁ ), the subpixels [R, G, B] A process is performed in which the light source luminance Y ₂ of the light source unit for setting the luminance of the display to the display luminance and the second prescribed value y ₂ is obtained.

That is, in Example 1, even if it is the darkest light source unit in this state, a light source brightness is (Y _Lk ). The state of the light source luminance (light source luminance 2) in this state is schematically shown in Fig. 1C, and the display luminance state is shown in Fig. 1D.

By the way, as mentioned above, the light transmittance of a liquid crystal cell cannot normally be made into "0" completely. Therefore, even if the light transmittance (opening ratio) of each subpixel is a minimum, the omission of light from a liquid crystal cell will arise. As a result, in the high luminance light emission display area unit, the input signal corresponding to the control signal to a certain pixel is the maximum input signal in the display area unit, and has a large value (x _H ) while It presented to the other pixels constituting the display area unit that the control signal is supplied which corresponds to the input signal of low value (x _L), and the low luminance input of all the pixels to a lower value (x _L) constituting the light emission, the display area unit Even when it is assumed that a control signal corresponding to the signal is supplied (see FIG. 1A), as shown schematically in FIG. 1D, display luminance (yy) in other pixels constituting the high luminance light emitting display region unit is shown. _The difference between _L 'and display luminance (y _L ') in the pixels constituting the low luminance light emitting display area unit can be made smaller than that shown in Fig. 11C. Therefore, the black display portion cannot be observed as if it floats, and a consistently low display luminance state can be obtained, and the quality of the image display can be improved.

On the other hand, when the low luminance light emitting display area unit present flag is "0", or when the high luminance light emitting display area unit present flag is "0", all the light source units 42 _{(q, p)} For example, the following processing is performed. That is, the control signals [R, G, B] _{(q, p)} corresponding to the maximum and maximum input signals (value: x _{U -max (q, p)} ) in the display area unit are subpixels [R, G, B]. Assume that it has been supplied to _{(q, p)} , and furthermore, it is assumed that the light transmittance (opening ratio) of the subpixels [R, G, B] _{(q, p)} at this time is corrected to the light transmittance and the first prescribed value Lt ₁ . when, the sub-pixels [R, G, B] _{(q, p)} the brightness of the display luminance · second specified value of _- in the _{(y 2 (q, p)} ) the light source unit _{(42) (q, p)} for a The processing as to obtain light source luminance Y _{2- (q, p)} is performed.

In the processing in [Step-120] described above, more specifically, the light source luminance (Y ₂ ＇, Y) per one light source unit for each image display frame so as to satisfy the following equation (1). ₂ ) can be controlled. In other words, the brightness of the light source 41 is controlled based on equation (2) which is a light source brightness control function g (x _{nol -max} ), while the light source brightness Y ₂ ＇, Y ₂ is satisfied to satisfy equation (1). Good to control. The conceptual diagram of such control is shown to FIG. 8A and FIG. 8B. However, as described later, correction based on the influence of the other light source unit 42 needs to be performed with respect to the light source luminances Y ₂ ＇and Y ₂ . Further, these relations regarding the control of the light source luminances Y ₂ ＇, Y ₂ , that is, the values (x _{U -max} , x＇ _U-max ) of the maximum and maximum input signals in the display area unit, and the maximum value (x _{U The} value of the control signal corresponding to the input signal having the same value as _-max , x ＇ _U-max ), and the display luminance when the control signal is supplied to the pixel (subpixel) and the second regulation value (y ₂ ) Display luminance when the light transmittance (opening ratio) [light transmittance, second regulation value (Lt ₂ )] of each subpixel at this time, and the light transmittance (opening ratio) of each subpixel are set to light transmittance, first regulation value (Lt ₁ ). The relationship between the brightness control parameters in the light source unit from which the second prescribed values Y ₂ ＇and Y ₂ are obtained may be obtained in advance and stored in the storage device 72 or the like.

_{Y 2 · Lt 1 = Y 1} · Lt 2 (One)

g (x _{nol -max} ) = a ₁ (x _{nol -max} ) ^2.2 + a ₀ (2)

Here, input signals (input signals [R, G, B]) input to the liquid crystal display drive circuit 90 to drive the pixels (or each of the subpixels [R, G, B] constituting the pixels). When the maximum value of) is (x _In-max ),

x _{nol -max} ≡x _{U -max} / x _{In -max}

, A ₁ , a ₀ are integers,

a ₁ + a ₀ = 1

0 <a ₀ <1, 0 <a ₁ <1

It can be represented as. For example,

a ₁ = 0.99

a ₀ = 0.01

It is good to do. In addition, since each of the values (x _R , x _G , x _B ) of the input signals [R, G, B] takes values of 2 ⁸ steps, the value of (x _{In -max} ) corresponds to "255". Is a value.

By the way, in the back light, for example, (p, q) = (1, 1) of the light source unit 42. When the luminance assumed for the control of the _{(1, 1),} other P × Q of the light source unit (42 Need to consider the impact from Since the influence of the light source unit 42 from the other light source units 42 is determined in advance by the light emission profile of each light source unit 42, the difference can be calculated by inversion, and as a result, correction is possible. Do. The basic types of operations are described below.

The luminance (light source luminance Y ₂ ＇, Y ₂ ) required for the P × Q light source units 42 based on the requests of formulas (1) and (2) is represented by a matrix [L _PxQ ]. In addition, the luminance of a light source unit obtained when only one light source unit is driven and the other light source unit is not driven is obtained in advance for the P × Q light source units 42. The luminance concerned is represented by a matrix [L ＇ _PxQ ]. In addition, the correction coefficient is represented by a matrix [α _PxQ ]. Then, the relationship of such a matrix can be represented by the following formula | equation (3-1). The matrix [α _PxQ ] of the correction coefficients can be obtained in advance.

[L _PxQ ] = [L ＇ _PxQ ] · [α _PxQ ] (3-1)

By doing so, the matrix [L ＇ _PxQ ] may be obtained from equation (3-1). The matrix [L ＇ _PxQ ] can be obtained from the calculation of the inverse matrix. In other words,

[L ＇ _PxQ ] = [L _PxQ ] · [α _PxQ ] ^-1 (3-2)

Calculate Then, as the luminance represented by the matrix [L _{좋고 PxQ} ] is obtained, the light source 41 _{(q, p)} may be controlled. Specifically, the operation and processing involved are stored in the storage device (memory) 82. This may be done using the stored information (data table). In addition, in the control of the light sources 41 _{(q, p)} , since the value of the matrix [L ＇ _PxQ ] does not take a negative value, it goes without saying that the calculation result needs to be set in the positive region. Therefore, the solution of Formula (3-2) is not exact but may be approximate.

Thus, the matrix [L _PxQ ] obtained on the basis of the values of the formulas (1) and (2) obtained in the calculation circuit 71 constituting the backlight control circuit 70 and the matrix [α _PxQ ] of the correction coefficients. On the basis of the above, as described above, the matrix of luminance when the light source unit was driven alone [L ＇ _PxQ ] is calculated and converted into a corresponding integer in the range of 0 to 255 based on the conversion table stored in the storage device 72. In this way, in the arithmetic circuit 71 constituting the backlight control circuit 70 _, the emission time of the red light emitting diodes 41R _{(q, p) in} the light source unit 42 _{(q, p)} is controlled. The value of the pulse width modulated output signal S _{R-(q, p)} to control the light emission time of the green light emitting diode 41G _{(q, p)} (S _{G- ( q, p)} ), and the value S _{B- (q, p)} of the pulse width modulation output signal for controlling the light emission time of the blue light emitting diode 41B _{(q, p)} can be obtained.

[Step -130]

Next, the values S _{r-(q, p)} , S _{G- (q, p)} and S _{B -of the} pulse width modulated output signal obtained in the arithmetic circuit 71 constituting the backlight control circuit 70. for _{(q, p)),} the light source unit (42), _{(q, p)} in the installed and sent out to the storage device 82 to the light source unit drive circuit (80), _{(q, p),} the storage device 82 corresponding to the Is remembered. The clock signal CLK is also sent to the light source unit driving circuit 80 _{(q, p)} (see Fig. 5).

Then, based on the values S _{R-(q, p)} , S _{G- (q, p)} and S _{B- (q, p)} of the pulse width modulated output signal, the light source unit 42 _{(q, p) )} to configure a red light emitting diode (41R), _{(q, p-on} time (t _R-oN) and off-time (t _R-oFF) of _a), a green light emitting diode _{(41G) (q,} on time of the _p) (t that _G-ON ) and the off time (t _G-OFF ), the on time (t _B-ON ) and the off time (t _B-OFF ) of the blue light emitting diode 41B _{(q, p} ) are calculated by the calculation circuit (81). Decide. Also,

t _R-ON + t _R-OFF = t _G-ON + t _G-OFF = t _B-ON + t _B-OFF = _Constant t _Const

to be. The duty ratio in driving based on pulse width modulation of the light emitting diode is t _ON / (t _ON + t _OFF ) = t _ON / t _Const

It can be represented as.

Then, the red light emitting diodes 41R _{(q, p)} constituting the light source unit 42 _{(q, p)} , the green light emitting diodes 41G _{(q, p)} , and the blue light emitting diodes 41B _{(q, p)} Signal corresponding to the ON time (t _{R-ON- (q, p)} , t _{G-ON- (q, p)} , t _{B-ON- (q, p)} ) of the LED driver circuit 83 From this LED drive circuit 83, it corresponds to the on time t _{R-ON- (q, p)} , t _{G-ON- (q, p)} , t _{B-ON- (q, p)} Based on the value of the signal, the switch element (85R) _{(q, p)} , (85G) _{(q, p)} , (85B) _{(q, p} ) has the on time t _{R-ON- (q , p)} , t _{G-ON- (q, p)} , t _{B-ON- (q, p)} ) are turned on, and the LED driving current from the LED driving power supply 86 is changed to each light emitting diode ( 41R) _{(q, p)} , (41G) _{(q, p)} , (41B) _{(q, p)} flows. As a result, each light emitting diode 41R _{(q, p)} , (41G) _{(q, p)} , (41B) _{(q, p)} has an on time t _{R-ON- ( q, p)} , t _{G-ON- (q, p)} , t _{B-ON- (q, p)} ). In this way, the (p, q) th display area unit 12 _{(q, p)} is illuminated at a predetermined illuminance.

Although the state obtained in this way is shown by the solid line in FIGS. 9A and 9B, FIG. 9A is a value obtained by multiplying the value of the input signal input to the liquid crystal display drive circuit 90 by 2.2 to drive the subpixel (≡x ^2.2). ) And the relationship between the duty ratio (= t _ON / t _Const ) and FIG. 9B shows the value X and the display luminance y of the control signal for controlling the light transmittance Lt of the subpixel. It is a figure which shows typically the relationship with).

[Step -140]

On the other hand, the values (x _{R- (q, p)} , x _{G- (q, p)} , x _B of the input signals [R, G, B] _{(q, p)} input to the liquid crystal display driving circuit 90 _{-(q, p)} ) is sent to the timing controller 91, and in the timing controller 91, the control signal [R, G corresponding to the input signal [R, G, B] _{(q, p)} inputted. , B] _{(q, p)} is supplied (outputted) to the subpixels [R, G, B] _{(q, p)} . A control signal [R, generated in the timing controller 91 of the liquid crystal display driving circuit 90 and supplied to the subpixels [R, G, B] _{(q, p)} from the liquid crystal display driving circuit 90. G, B] _{(q, p)} values (X _{R- (q, p)} , X _{G- (q, p)} , X _{B- (q, p)} ) and input signals [R, G, B] The value of _{(q, p)} (x _{R- (q, p)} , x _{G- (q, p)} , x _{B- (q, p)} ) is the following formula (4-1) and formula (4 -2) and the relationship of Formula (4-3). However, (b _{1 _R} , b _{0 _R} , b _{1 _G} , b _{0 _G} , b _{1 _B} , b _{0 _B} ) is an integer. In addition, since the light source luminances _{2- (q, p)} of the light source unit 42 _{(q, p)} are changed for each image display frame, the control signals [R, G, B] _{(q, p)} are basically For the value obtained by multiplying the value of the input signal [R, G, B] _{(q, p)} by 2.2, the value of the correction (compensation) based on the change in the light source luminance Y _{2- (q, p)} is obtained. Have That is, in the embodiment, since the light source luminance Y _{2- (q, p)} changes for every one image display frame, the display luminance at the light source luminance Y _{2- (q, p} ) (≤Y ₁ ) As the second prescribed value y _{2- (q, p)} is obtained, the values of the control signals [R, G, B] _{(q, p)} (X _{R- (q, p)} , X _{G- (q, p)} , X _{B- (q, p)} ) is determined and corrected (compensated), and the light transmittance (opening ratio) Lt of the subpixel is controlled. Here, the functions (f _R , f _G , f _B ) of the formulas (4-1), (4-2), and (4-3) are previously obtained functions for performing the relevant correction (compensation). to be.

X _{R- (q, p)} = f _R (b _{1 _Rx} x _{R- (q, p)} ^2.2 + b _{0 _R} ) (4-1)

X _{G- (q, p)} = f _G (b _{1 _Gx} x _{G- (q, p)} ^2.2 + b _{0 _G} ) (4-2)

X _{B- (q, p)} = f _B (b _{1 _Bx} x _{B- (q, p)} ^2.2 + b _{0 _B} ) (4-3)

In this way, the image display operation in one image display frame is completed.

Embodiment 2 relates to a display device and a driving method thereof according to the second aspect of the present invention. In Embodiment 2, in the backlight control circuit 70 and the light source unit driving circuit 80 corresponding to the control unit, the ratio RT ₁ of the low luminance light emitting display area unit is _equal to or greater than a predetermined value RT ₀ . On the other hand, when the high luminance light emitting display area unit exists in the vicinity of the low luminance light emitting display area unit, a process of increasing the luminance of the light source unit corresponding to the low luminance light emitting display area unit is performed. In addition, in Example 2 or Example 3 described later, the predetermined value (RT ₀ ) is examined to examine the relationship between the magnification (area) of the low luminance portion and the phenomenon observed as the black display portion floats. Decided to.

Hereinafter, the driving method of the display device in Example 2 is demonstrated again with reference to FIG. 1 and FIG.

[Step -200]

First, the same steps are executed in [Step-100] of the first embodiment.

[Step -210]

Next, the same steps are executed in [Step-110] of the first embodiment, and the values (x _{U -max ( )} of the maximum and maximum input signals in the display area units of all the display area units 12 _{(q, p)} are executed. _{q, p)} ) is stored in the storage device 72.

At the same time, in the arithmetic circuit 71, all of the low luminance light emitting display area units whose value (x _{U-max (q, p)} ) in the display area unit and the maximum input signal are equal to or less than the _first specified value PD ₁ . Find the ratio (RT ₁ ) to the display area units (P × Q). When the ratio RT ₁ of the low luminance light emitting display area unit is equal to or greater than a predetermined value RT ₀ , the positions p and q of the low luminance light emitting display area unit are stored in the storage device 72. The low luminance light emitting display area unit present flag is changed from the initial value "0" already reset. Further, in the arithmetic circuit 71, the value _{( xU -max (q, p)} ) in the display area unit / maximum input signal exceeds the same value as the second prescribed value PD ₂ or the second specified value. It is checked whether or not the high luminance light emitting display area unit as a value exists around the low luminance light emitting display area unit, and if such a high luminance light emitting display area unit exists, the position (p, q) is stored in the storage device 72. ), And change the high luminance light emitting display area unit present flag from the initial value "0" already reset.

In Example 2, the high luminance light emitting display area unit is adjacent to each other in the direction of the low luminance light emitting display area unit in the direction of both sides (to be adjacent to each other). In this case, it is assumed that the high luminance light emitting display area unit exists around the low luminance light emitting display area unit.

Light transmittance (opening ratio) in the pixels constituting the display area unit when the low luminance light emission display area unit present flag is "1" and the high luminance light emission display area unit present flag is "1". The state of the input signal for controlling the state and the light source luminance (light source luminance 1) state in this state are the same as those shown in Figs. 1A and 1B.

[Step -220]

Next, when the low luminance light emission display area unit present flag is "1" and the high luminance light emission display area unit present flag is "1", the light source unit corresponding to the low luminance light emission display area unit Although the process of increasing the brightness is performed, specifically, the same steps as in [Step-120] of the first embodiment may be performed. The state of the light source luminance (light source luminance 2) and the display luminance state in the state thus obtained are the same as those shown in Figs. 1C and 1D.

On the other hand, even when the low luminance light emitting display area unit present flag is "0" or when the high luminance light emitting display area unit present flag is "0", it is the same as [Step-120] of Example 1 You may execute the step.

[Step -230]

Further, by executing the same steps as in [Step-130] and [Step-140] of Example 1, the image display operation in one image display frame is completed.

Embodiment 3 relates to a display device and a driving method thereof according to the third aspect of the present invention. In Embodiment 3, in the backlight control circuit 70 and the light source unit driving circuit 80 corresponding to the control unit, the ratio RT ₁ of the low luminance light emission display unit is more than a predetermined value RT ₀ . On the other hand, when there are a plurality of continuous low luminance light emitting display unit units adjacent to a plurality of continuous low luminance light emitting display unit units (in the third embodiment, R = 2), the high luminance light emitting display unit is close to the high luminance light emitting display unit. A process of increasing the luminance by the light source unit corresponding to the low luminance light emission display unit is performed.

Hereinafter, the driving method of the display device in Example 3 is demonstrated with reference to FIG. 2 and FIG.

[Step -300]

First, the same steps as in [Step-100] of the first embodiment are executed.

[Step -310]

Next, the same steps as in [Step-110] of the first embodiment are executed, and the values (x _{U -max ( )} of the maximum and maximum input signals in the display area units in all the display area units 12 _{(q, p)} are executed. _{q, p)} ) is stored in the storage device 72.

Similarly, in the arithmetic circuit 71, the value of the low luminance light emission / display area unit in which the value (x _{U-max (q, p)} ) in the display area unit and the maximum input signal is equal to or less than the _first specified value PD ₁ . Find the ratio (RT ₁ ) for all display area units (P × Q). When the ratio RT ₁ of the low luminance light emitting display area unit is equal to or greater than a predetermined value RT ₀ , the positions p and q of the low luminance light emitting display area unit are stored in the storage device 72. The low luminance light emitting display area unit present flag is changed from the initial value "0" already reset. Further, in the arithmetic circuit 71, the value (x _{U -max (q, p)} ) of the display area unit / maximum input signal is equal to the second prescribed value PD ₂ or the second specified value. It is checked whether or not the high luminance light emitting display area unit that is an excess value exists adjacent to a plurality of consecutive low luminance light emitting display area units, and if such high luminance light emitting display area unit exists, the position (p, q). Is stored in the storage device 72, and the high luminance light emitting display area unit present flag is changed from the initial value "0" already reset.

Also in Example 3, the high luminance light emitting display area unit is adjacent to one end of the continuous low luminance light emitting display area unit in either direction of the low luminance light emitting display area unit ( Adjacent to each other), a high luminance light emitting display area unit exists adjacent to a low luminance light emitting display area unit. Light transmittance (opening ratio) in the pixels constituting the display area unit when the low luminance light emission display area unit present flag is "1" and the high luminance light emission display area unit present flag is "1". 2A and 2B show the state of an input signal for controlling the state and the state of the light source luminance (light source luminance 1) in this state.

[Step -320]

Next, when the low luminance light emission display area unit present flag is "1" and the high luminance light emission display area unit present flag is "1", the light source unit corresponding to the low luminance light emission display area unit Although the process which increases a brightness | luminance is performed, the following process is specifically implemented. That is, in Example 3, since R = 2, two consecutive low luminance light emission display area units based on the position of the high luminance light emission display area unit [first low luminance light emission display area unit] And the second low luminance light emission display area unit, in the light source unit corresponding to the r th light emission r display area unit (r = 1, 2). It is assumed that the control signals [R, G, B] corresponding to the input signals (value: x ” _U-max (r)) are supplied to the subpixels [R, G, B]. , G, B] the light transmittance (aperture ratio), the light transmittance · first specified value, assuming that the correction (Lt _1), the sub-pixels [R, G, B] the display luminance · second specified value luminance of the (y ₂ To obtain the light source luminance Y ₂ (r) ”of the light source unit for The processing as described above is carried out. Here, the value (x ” _U-max (r)) of the maximum input signal in the display area unit is

x ” _U-max (r) = β ₁ ^rx _MAX (Where 0 <β ₁ <1)

or,

_{x "U-max (r)} = (1-β 2 · r) x MAX (0 <β ₂ <1)

If you are satisfied. Although the state of the light source luminance (light source luminance 2) in this state is schematically shown in FIG. 2C and the display luminance state is shown in FIG. 2D, the value (x ” _U-max ( The light source luminance of the light source unit corresponding to r)) is represented by (Y _L (r) ”, and the display brightness is represented by (y _L (r)”). In addition, the display luminance in other pixels constituting the high luminance light emitting display area unit is indicated by (yy _L ″).

On the other hand, even when the low luminance light emitting display area unit present flag is "0" or when the high luminance light emitting display area unit present flag is "0", it is the same as [Step-120] of Example 1 You may execute the step.

[Step -330]

Further, by executing the same steps as in [Step-130] and [Step-140] of Example 1, the image display operation in one image display frame is completed.

As mentioned above, although this invention was demonstrated based on the preferable Example, this invention is not limited to this Example. The structure and structure of the transmissive color liquid crystal display device, the backlight, the light source unit, the display device, and the control unit described in the embodiments are exemplifications, and the members, materials, etc. constituting them are examples, and can be changed as appropriate. By monitoring the temperature of the light emitting diode with a temperature sensor and feeding the result back to the light source unit driving circuit 80, luminance compensation (correction) and temperature control of the light source unit 42 may be performed. In the embodiment, the explanation is given assuming that the display area of the liquid crystal display device is divided into P × Q virtual display area units. However, in some cases, the transmissive liquid crystal display device displays P × Q actual displays. The area unit may have a divided structure.

In the present invention, when the low luminance light emitting display area unit satisfies a specific condition and the positional relationship between the low luminance light emitting display area unit and the high luminance light emitting display area unit satisfies a predetermined relationship, A process of increasing the luminance of the light source unit corresponding to the light emitting display area unit is performed. Therefore, even when there is a bright image display portion in the vicinity where the dark image display portion is spreading, the display luminance state of the dark image display portion can be made as uniform as possible, and the black display portion is observed to float, and the low It is possible to reliably avoid the occurrence of a problem that the display luminance state is not obtained and the quality of the image display is deteriorated.

In addition, the luminance of the pixel when the control signal corresponding to the input signal having the same value as the value (x _{U -max} ) in the display area unit and the maximum input signal is supplied to the pixel (the light transmittance and the first prescribed value) As the display luminance and the second prescribed value y ₂ ) in Lt ₁ ) are obtained, the luminance of the light source constituting the light source unit corresponding to the display area unit is controlled by the driver so that the power consumption of the backlight is reduced. Not only can the reduction be achieved, but also the increase of the white level and the decrease of the black level can be achieved, and the high contrast ratio (the brightness of the whole black display unit and the white display unit, which does not include external light reflection or the like on the screen surface of the liquid crystal display device). B) and the brightness of the desired display area can be emphasized, so that the quality of the image display can be improved.

Claims (12)

(a) a display portion comprising a transmissive liquid crystal display device having a display area composed of pixels arranged in a matrix, (b) a back light for illuminating a rear surface of the display unit, comprising a light source unit individually disposed corresponding to a plurality of display area units constituting the display area; (c) a display device having a display portion and a driving portion for driving the backlight based on an input signal from the outside, The driving unit has a control unit for controlling the light emitting state of the light source unit corresponding to the display area unit on the basis of the maximum input signal in the display area unit having the maximum value in the input signal corresponding to each display area unit, The control unit, The presence or absence of the low luminance light emitting display area unit whose value of the maximum input signal in the display area unit is equal to or less than the first prescribed value is examined. The high luminance light emitting display area unit whose value of the input signal within the display area unit is the same as the second prescribed value which is greater than the first prescribed value or exceeds the second prescribed value is used for the low luminance light emitting display area unit. Check whether it's around or not, A display device characterized by performing a process of increasing the luminance of a light source unit corresponding to the low luminance light emitting display area unit when the high luminance light emitting display area unit is present in the vicinity of the low luminance light emitting display area unit. The method of claim 1, The first prescribed value is any one of 25% or less of the maximum value of the input signal. The method of claim 1, The second prescribed value is any value exceeding 25% of the maximum value in the value of the maximum input signal in the display area unit. (a) a display portion comprising a transmissive liquid crystal display device having a display area composed of pixels arranged in a matrix, (b) a back light for illuminating a rear surface of the display unit, comprising a light source unit individually disposed corresponding to the plurality of display area units constituting the display area; (c) a display device having a display portion and a driving portion for driving the backlight based on an input signal from the outside, The driving unit has a control unit for controlling the light emission state of the light source unit corresponding to this display area unit on the basis of the maximum input signal in the display area unit having the maximum value in the input signal corresponding to each display area unit, The control unit, The ratio of the low luminance light emitting display area unit to all display area units whose value of the maximum input signal in the display area unit is equal to or less than the first prescribed value is calculated; The high luminance light emitting display area unit whose value of the input signal within the display area unit is the same as the second prescribed value which is greater than the first prescribed value or exceeds the second prescribed value is used for the low luminance light emitting display area unit. Check whether it's around or not, The light source corresponding to the low luminance light emitting display area unit when the ratio of the low luminance light emitting display area unit is greater than or equal to a predetermined value and the high luminance light emitting display area unit is present in the vicinity of the low luminance light emitting display area unit. A display apparatus characterized by performing a process of increasing the luminance of a unit. The method of claim 4, wherein The first prescribed value is any one of 25% or less of the maximum value of the input signal. The method of claim 4, wherein The second prescribed value is any value exceeding 25% of the maximum value in the value of the maximum input signal in the display area unit. (a) a display portion comprising a transmissive liquid crystal display device having a display area composed of pixels arranged in a matrix, (b) a back light for illuminating a rear surface of the display unit, comprising a light source unit individually disposed corresponding to the plurality of display area units constituting the display area; (c) a display device having a display portion and a driving portion for driving the backlight based on an input signal from the outside, The driving unit has a control unit for controlling the light emitting state of the light source unit corresponding to the display area unit on the basis of the maximum input signal in the display area unit having the maximum value in the input signal corresponding to each display area unit, The control unit, The ratio of the low luminance light emitting display area unit to all display area units whose value of the maximum input signal in the display area unit is equal to or less than the first prescribed value is calculated; A plurality of continuous low-luminance light emission and display devices having a high luminance light emitting display area unit having a value equal to or higher than a second prescribed value having a value greater than or equal to a first prescribed value in the display area unit and having a value larger than the first prescribed value. Checks whether or not it is adjacent to the display area unit, When the ratio of the low luminance light emitting display area unit is equal to or greater than a predetermined value and there is a high luminance light emitting display area unit adjacent to a plurality of consecutive low luminance light emitting display area units, the high luminance light emitting display area unit is present. A display device characterized by performing a process of increasing luminance by a light source unit corresponding to a near low luminance light emitting display area unit. The method of claim 7, wherein The first prescribed value is any one of 25% or less of the maximum value of the input signal. The method of claim 7, wherein The second prescribed value is any value exceeding 25% of the maximum value in the value of the maximum input signal in the display area unit. (a) a display portion comprising a transmissive liquid crystal display device having a display area composed of pixels arranged in a matrix, (b) a back light for illuminating a rear surface of the display unit, comprising a light source unit individually disposed corresponding to the plurality of display area units constituting the display area; (c) a display section and a driving section for driving the backlight, based on an input signal from the outside, The driving unit drives the display device having a control unit for controlling the light emission state of the light source unit corresponding to the display area unit on the basis of the maximum input signal in the display area unit having the maximum value in the input signal corresponding to each display area unit. Way, The control unit checks for the presence or absence of the low luminance light emitting display area unit whose value of the maximum input signal in the display area unit is equal to or less than the first prescribed value, The high luminance light emitting display area unit whose value of the input signal within the display area unit is the same as the second prescribed value which is greater than the first prescribed value or exceeds the second prescribed value is used for the low luminance light emitting display area unit. The controller checks whether or not it is in the vicinity. When the high luminance light emitting display area unit exists in the vicinity of the low luminance light emitting display area unit, the display apparatus characterized in that the control unit performs processing for increasing the luminance of the light source unit corresponding to the low luminance light emitting display area unit. Driving method. (a) a display portion comprising a transmissive liquid crystal display device having a display area composed of pixels arranged in a matrix, (b) a backlight unit composed of light source units individually disposed corresponding to the plurality of display area units constituting the display area, and illuminating the rear surface of the display unit; (c) a display section and a driving section for driving the backlight, based on an input signal from the outside, The driving unit drives the display device having a control unit for controlling the light emission state of the light source unit corresponding to the display area unit on the basis of the maximum input signal in the display area unit having the maximum value in the input signal corresponding to each display area unit. Way, The control unit obtains the ratio of the low luminance light emitting display area unit to all the display area units whose value of the maximum input signal within the display area unit is equal to or less than the first prescribed value. The high luminance light emitting display area unit whose value of the input signal within the display area unit is the same as the second prescribed value which is greater than the first prescribed value or exceeds the second prescribed value is used for the low luminance light emitting display area unit. The controller checks whether or not it is in the vicinity. The light source corresponding to the low luminance light emitting display area unit when the ratio of the low luminance light emitting display area unit is greater than or equal to a predetermined value and the high luminance light emitting display area unit exists near the low luminance light emitting display area unit. A control method for driving a display device, characterized in that the control unit performs a process of increasing the luminance of the unit. (a) a display portion comprising a transmissive liquid crystal display device having a display area composed of pixels arranged in a matrix, (b) a back light for illuminating a rear surface of the display unit, comprising a light source unit individually disposed corresponding to the plurality of display area units constituting the display area; (c) a display section and a driving section for driving the backlight, based on an input signal from the outside, The driving unit drives the display device having a control unit for controlling the light emission state of the light source unit corresponding to the display area unit on the basis of the maximum input signal in the display area unit having the maximum value in the input signal corresponding to each display area unit. Way, The ratio of the low luminance light emitting display area unit to the entire display area unit in which the value of the input signal in the display area unit and the maximum input signal is equal to or less than the first prescribed value is determined by the controller. Meanwhile, A plurality of continuous low-luminance light emission and display devices having a high luminance light emitting display area unit having a value equal to or higher than a second prescribed value having a value greater than or equal to a first prescribed value in the display area unit and having a value larger than the first prescribed value. The controller checks whether or not it is adjacent to the display area unit, When the ratio of the low luminance light emitting display area unit is equal to or greater than a predetermined value, and there is a high luminance light emitting display area unit adjacent to a plurality of consecutive low luminance light emitting display area units, the high luminance light emitting display area unit is present. A driving method of a display device, characterized in that the control unit performs a process of increasing the luminance by a light source unit corresponding to a near low luminance light emitting display area unit.

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