JP2010039248A - Liquid crystal display, color modulation method, color modulation program, and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inexpensive liquid crystal display or the like capable of reproducing a color of high quality at a low electric power consumption. <P>SOLUTION: In this liquid crystal display 81, a light intensity of a fluorescent tube 72 is regulated in response to an image signal serving as a basis of an image, and a color image signal included in the image signal is worked matched with the light intensity of the fluorescent tube 72, to modulate the color of the image. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device. The present invention also relates to a method for modulating the color of an image displayed on a liquid crystal display device, a color modulation program for the color modulation, and a recording medium on which the color modulation program is recorded.

  Usually, in a liquid crystal display device equipped with a non-light emitting liquid crystal display panel, a backlight unit for supplying light to the liquid crystal display panel is also mounted. For example, as shown in the cross-sectional view of FIG. 10, the backlight unit includes a plurality of fluorescent tubes 172 that emit white light, and causes the white light to reach the liquid crystal display panel 161 via the diffusion sheet 173.

  In such a liquid crystal display device 181, if the luminance of the image on the liquid crystal display panel 161 is to be improved, the light intensity of the white light emitting fluorescent tube 172 in the backlight unit 171 is increased. However, the following problems occur. That is, even when an image that emphasizes a specific color (an image in which the specific color has a relatively high color purity) is to be displayed, since the light emitted from the fluorescent tube 72 is white, The problem is that only the light intensity cannot be increased.

  Such a problem is caused by the fact that the fluorescent tube 172 has a relatively high light intensity in each of the red wavelength range, the green wavelength range, and the blue wavelength range, as shown in the spectrum diagram of FIG. This is because the light intensity of other colors is also increased.

  Therefore, recently, a backlight unit 171 having a red light source, a green light source, and a blue light source has been developed. For example, in the case of the backlight unit 171 of Patent Document 1, an LED (Light Emitting Diode) is employed as a light source. That is, a red light emitting LED, a green light emitting LED, and a blue light emitting LED are employed in the backlight unit 171.

The spectrum diagram of these three color LEDs is as shown in FIG. 12 (R, G, and B in the figure correspond to the emission colors of red, green, and blue). As is clear from this figure, each LED is centered on a specific wavelength and does not contain energy of other wavelengths. Therefore, with such a backlight unit 171, high-quality white light is generated by color mixing. Further, with this backlight unit 171, when an image that emphasizes a specific color is displayed, the light intensity of the LED that matches the specific color can be increased.
JP 2008-153014 A

  However, the image displayed on the liquid crystal display panel 161 may not only emphasize the specific color but also suppress the specific color. When the specific color is suppressed in this way, it is conceivable to reduce the light intensity of some LEDs in the backlight unit 171.

  However, the luminous efficiency (lumens / watt) of the LED is often about half of the luminous efficiency of the fluorescent tube 172 in many cases. In particular, the luminous efficiency of green LEDs is lower than the luminous efficiency of LEDs of other colors. Therefore, in the recent large-screen and thin liquid crystal display device 181, reducing the light intensity of some LEDs causes a decrease in luminance with respect to the entire image, which is a problem.

  Moreover, in order to prevent such a brightness | luminance fall, mounting a lot of LED is also considered. However, LEDs are more expensive than fluorescent tubes 172. Therefore, when such a preventive measure is performed, the cost of the backlight unit 171 and, consequently, the liquid crystal display device 181 increases. Further, the power consumption of such a liquid crystal display device 81 tends to increase.

  In addition, as shown in FIG. 12, the three-color LED has sufficient energy for a specific wavelength, but hardly has energy for other wavelengths. For this reason, when the light intensity of some LEDs is lowered, the color of the image is remarkably changed, which may stand out.

  The present invention has been made to solve the above problems. An object of the present invention is to provide a liquid crystal display device that is inexpensive, low power consumption, and capable of reproducing high-quality colors.

  The liquid crystal display device includes a liquid crystal display panel that displays an image, and a backlight unit that includes a plurality of linear light sources that emit different colors, generates white color by color mixture, and irradiates the liquid crystal display panel. Further, the liquid crystal display device receives a video signal as a basis of an image, calculates a chromaticity from the color video signal in the video signal, and corresponds to the chromaticity, and emits light from some linear light sources. Obtain a light intensity modulation signal for reducing the intensity below the light intensity of the remaining linear light source, and further obtain a processed color video signal that processes the color video signal corresponding to the light intensity modulation signal. Includes a display controller.

  Since such a liquid crystal display device includes a relatively inexpensive linear light source, the cost can be reduced. In addition, the display control unit can turn off some of the linear light sources in accordance with the video signal. Therefore, power consumption can be suppressed. Even if some linear light sources are turned off, the color video signal is processed in accordance with the remaining linear light sources, so that the quality of the image can be maintained.

  A storage unit for storing the light intensity modulation signal and the processed color video signal is included, and the display control unit acquires the light intensity modulation signal and the processed color video signal from the storage unit without acquiring the light intensity modulation signal and the processed color video signal by generation. May be.

  The backlight unit preferably includes a red light-emitting linear light source, a green light-emitting linear light source, and a blue light-emitting linear light source in order to generate white light.

  In addition, the liquid crystal display panel includes a red color filter, a green color filter, and a blue color filter. The spectral characteristics of the red color filter and the spectral characteristics of the linear light source emitting red light are approximated, and the green color filter It is desirable that the spectral characteristics and the spectral characteristics of the green light-emitting linear light source approximate, and the spectral characteristics of the blue color filter and the spectral characteristics of the linear blue light-emitting light source approximate.

  Further, a diffusion sheet for diffusing light is interposed between the liquid crystal display panel and the backlight unit, and the distance between the diffusion sheet and the light source is such that the width of the light flux diverging from the linear light source and the width of the diffusion sheet are increased. It is desirable that the interval matches.

  By the way, the above color modulation in the liquid crystal display device can be grasped from the viewpoint of the method. That is, a liquid crystal display device that includes a liquid crystal display panel that displays an image and a backlight unit that includes a plurality of linear light sources that emit different colors, generates white color by mixing colors, and irradiates the liquid crystal display panel. It can be grasped as a color modulation method.

  In the color modulation method, a chromaticity calculation step of receiving a video signal that is a basis of an image and calculating chromaticity from the color video signal in the video signal, and a part of lines corresponding to the chromaticity A light intensity modulation signal acquisition step for acquiring a light intensity modulation signal for lowering the light intensity of the linear light source from the light intensity of the remaining linear light sources, and processing the color video signal corresponding to the light intensity modulation signal A processed initial video signal acquisition step of acquiring a processed color video signal.

  The color modulation in the above liquid crystal display device can also be grasped as a program. That is, a liquid crystal display panel that displays an image, a backlight unit that has a plurality of linear light sources that emit different colors, generates white by mixing colors, and irradiates the liquid crystal display panel; It can be grasped as a color modulation program of a liquid crystal display device including a display control unit for controlling the light quantity of the light unit.

  In the color modulation program, the video signal that is the basis of the image is received, the chromaticity is calculated from the color video signal in the video signal, and the light of some linear light sources is associated with the chromaticity. Obtain a light intensity modulation signal for reducing the intensity below the light intensity of the remaining linear light source, and further obtain a processed color video signal that processes the color video signal corresponding to the light intensity modulation signal. The display control unit is caused to execute display control.

  A computer-readable recording medium in which the above color modulation program is recorded can also be said to be the present invention.

  According to the present invention, the display control unit turns off some of the linear light sources, processes the color video signal in accordance with the remaining linear light sources, and displays an image on the liquid crystal display panel based on the processed color video signal. Therefore, the liquid crystal display device can maintain the quality of the image and suppress the power consumption. In addition, since a relatively inexpensive linear light source is included, the cost of the liquid crystal display device is reduced.

[Embodiment 1]
The following describes one embodiment with reference to the drawings. For convenience, member codes and the like may be omitted, but in such a case, other drawings are referred to.

  FIG. 2 is an exploded perspective view of the backlight type liquid crystal display device 81. As shown in this figure, the liquid crystal display device 81 includes a liquid crystal display panel 61 and a backlight unit 71 that supplies light to the liquid crystal display panel 61.

  The liquid crystal display panel 61 employs an active matrix method. Therefore, in the liquid crystal display panel 61, liquid crystal (non-liquid crystal) is formed by an active matrix substrate 62 to which an active element (switching element) such as a TFT (Thin Film Transistor) 65 is attached and an opposing substrate 64 facing the active matrix substrate 63. (Shown). That is, the active matrix substrate 62 and the counter substrate 67 are substrates for sandwiching liquid crystal, and are formed of transparent glass or the like.

  On the active matrix substrate 62, a gate signal line 63, a source signal line 64, a TFT 65, and a pixel electrode 66 are formed on one side facing the counter substrate 67.

  The gate signal line 63 is a line through which a gate signal (scanning signal) for controlling ON / OFF of the TFT 65 flows, and the source signal line 64 is a line through which a source signal (image signal) required for image display flows. And these both lines 63 * 64 are arranged in a line, respectively. More specifically, on the active matrix substrate 62, the gate signal lines 63 arranged in a row intersect with the source signal lines 64 arranged in a row, and these lines 63 and 64 are arranged in a matrix. A region divided by the gate signal line 63 and the source signal line 64 corresponds to a pixel of the liquid crystal display panel 61.

  The gate signal flowing through the gate signal line 63 is generated by the gate driver 41, and the source signal flowing through the source signal line 64 is generated by the source driver 42 (see FIG. 1 described later).

  The TFT 65 is located at the intersection of the gate signal line 63 and the source signal line 64 and controls ON / OFF of each pixel in the liquid crystal display panel 61 (note that only a part of the TFT 65 is shown for convenience). That is, the TFT 65 controls ON / OFF of each pixel by the gate signal flowing through the gate signal line 63.

  The pixel electrode 66 is an electrode connected to the drain of the TFT 65 and is arranged corresponding to each pixel (that is, the pixel electrode 66 is spread in a matrix on the active matrix substrate 62). The pixel electrode 66 sandwiches the liquid crystal together with a common electrode 68 described later.

  A common electrode 68 and a color filter 69 are formed on one surface of the counter substrate 67 facing the counter substrate 67.

  Unlike the pixel electrode 66, the common electrode 68 is arranged corresponding to a plurality of pixels (that is, the common electrode 68 has an area that covers the plurality of pixels together on the counter substrate 67). The common electrode 68 sandwiches the liquid crystal together with the pixel electrode 66. As a result, the liquid crystal is controlled by the potential difference between the common electrode 68 and the pixel electrode 66.

  The color filter 69 is a filter that transmits light of a specific color. As an example, there are color filters 69 of red (R), green (G), and blue (B), which are the three primary colors of light (note that R, G, and B in FIG. means). Further, these color filters 69 are arranged in, for example, a stripe shape, a delta shape, or a square shape. These color filters 69 have spectral characteristics (spectral characteristics) as shown in FIG.

  In the liquid crystal display panel 61 as described above, when the TFT 65 is turned on with the gate signal voltage applied via the gate signal line 63, the source signal voltage on the source signal line 64 is changed to the pixel via the source / drain of the TFT 65. Applied to the electrode 66. Then, in accordance with the source signal voltage, the voltage of the source signal is written in the liquid crystal portion sandwiched between the pixel electrode 66 and the common electrode 68, that is, the pixel. On the other hand, when the TFT 65 is OFF, the source signal voltage is held by the liquid crystal and the capacitor (not shown).

  Next, the backlight unit 71 that supplies light to the liquid crystal display panel 61 will be described. The backlight unit 71 includes a fluorescent tube 72 and a diffusion sheet 73 (note that the fluorescent tube 72 is accommodated in a box-shaped housing 74).

  The fluorescent tubes 72 are light sources such as cold cathode fluorescent lamps (CCFLs), and are mounted in a plurality (only a part of the fluorescent tubes 72 are shown in the drawing). These fluorescent tubes 72 include a fluorescent tube 72R that emits red, a fluorescent tube 72G that emits green, and a fluorescent tube 72B that emits blue.

  The color emitted by the fluorescent tube (linear light source) 72 is determined by the phosphor applied to the inside of the glass tube in the fluorescent tube 72. That is, ultraviolet rays generated at a high voltage applied between the electrodes at both ends of the fluorescent tube 72 excite the R phosphor for red, the G phosphor for green, and the B phosphor for blue, so that the visible light region Changes to (red, green, blue) light. The spectrum diagrams of these fluorescent tubes 72R, 72G, and 72B are shown in FIGS. 4A to 4C, and the spectrum diagram (MBX) that collectively illustrates FIGS. 4A to 4C is FIG. 4D.

  The fluorescent tube 72 employs a pulse width modulation (PWM) method in which the amount of light is changed in accordance with a change in the time ratio (duty) between the lighting period and the extinguishing period within a short period called a PWM period. To do. And this light quantity control is performed via the light source control unit 51 (refer FIG. 1 mentioned later).

  The diffusion sheet 73 is positioned so as to cover the fluorescent tubes 72, diffuses the light from the fluorescent tubes 72 while mixing the colors, and spreads the light throughout the liquid crystal display panel 61. That is, in the backlight unit 71 as described above, the light from the fluorescent tube 72 is emitted as whitened planar light (backlight light) by the diffusion sheet 73 and reaches the liquid crystal display panel 61. .

  Here, various circuits included in the liquid crystal display device 81 on which the liquid crystal display panel 61 and the backlight unit 71 as described above are mounted will be described with reference to FIG. More specifically, the video signal processing unit (VSP) 21, display controller (DCR) 11, nonvolatile memory (NVM) 31, gate driver 41, source driver 42, and light source control unit (LCU) 51 included in the liquid crystal display device 81. explain.

  The video signal processing unit (VSP) 21 generates a video processing signal by processing a video signal, for example, a television video signal for television broadcasting or a video video signal for video. The video processing signal includes, for example, a color video signal indicating a color (a red video signal RS, a green video signal GS, a blue video signal BS, and the like) and a synchronization signal (a clock signal CLK, a vertical synchronization signal VS, And a horizontal synchronizing signal HS).

  Further, the video signal processing unit 21 may perform various correction processes such as γ correction, contrast correction, and color space conversion process on the color video signal.

  The display controller (DCR) 11 controls driving of the liquid crystal display panel 61 and the backlight unit 71 via the gate driver 41, the source driver 42, and the light source control unit 51. For such control, the display controller (display control unit) 11 includes a timing controller (TCR) 12, a frame data monitoring unit (FDM) 13, and a data conversion unit (DCN) 16.

  The timing controller 12 receives the synchronization signal from the video signal processing unit 21 and generates various timing signals. For example, the timing controller 12 transmits various timing signals to the gate driver 41, the source driver 42, and the light source control unit 51.

  More specifically, the timing controller 12 generates a timing signal such as a gate clock signal (GCK) and a gate start pulse (GSP) and transmits the timing signal to the gate driver 41, and also a source clock signal (SCK) and a source start pulse (SSP). ) And the like are transmitted to the source driver 42. In addition, the timing controller 12 generates a lighting timing signal that links driving (lighting / extinguishing) of the fluorescent tube 72 with driving of the liquid crystal display panel 61, and transmits it to the light source control unit 51.

  The frame data monitoring unit (FDM) 13 includes a frame memory (FMY) 14 and a chromaticity distribution calculation unit (CDC) 15.

  The frame memory 14 stores the color video signal for one screen (one frame) transmitted from the video signal processing unit 21. The chromaticity distribution calculation unit 15 calculates chromaticity from the color image signal for one screen transmitted from the frame memory 14, and further calculates chromaticity distribution data from the chromaticity. Then, the chromaticity distribution calculation unit 15 transmits the chromaticity distribution data to the data conversion unit 16.

  An example of the chromaticity distribution data is chromaticity (x, y) shown in a CIE Yxy chromaticity diagram defined by CIE (Commission Internationale de l'Eclairage) as shown in FIG. Note that the triangular graph line in FIG. 5 indicates the chromaticity distribution obtained by the color mixture of the fluorescent tubes 72R, 72G, and 72B (note that RGB is attached to this graph line for convenience).

  Further, RED, GREEN, and BLUE in FIG. 5 indicate rough colors in the chromaticity diagram. Also, the chromaticity of the vertices of the color triangular area (chromaticity distribution) formed by triangular graph lines, that is, the chromaticity of the vertices near RED, the chromaticity of the vertices near GREEN, and the chromaticity of the vertices near BLUE Are represented as (xr, yr), (xg, yg), (xb, yb) for convenience.

  The data conversion unit (DCN) 16 receives the chromaticity distribution data transmitted from the chromaticity distribution calculation unit 15 of the frame data monitoring unit 13. Then, the data converter 16 determines the light intensity of the fluorescent tube 72 (72R, 72G, 72B) required to reproduce the chromaticity distribution data, and sends a light intensity modulation signal indicating that to the light source control unit 51. Transmit (details will be described later).

  Further, the data conversion unit 16 refers to the chromaticity distribution data, and processes the processed color video signal (processed red signal R ′S, processed green signal G ′S, processed blue signal B ′S) that is the basis of the source signal. The data is transmitted to the source driver 42 (details will be described later).

  The nonvolatile memory (NVM) 31 stores the light intensity modulation signal and the processed color video signal transmitted from the data converter 16. That is, the light intensity modulation signal and the processed color video signal are calculated in advance, and the nonvolatile memory (storage unit) 31 includes a light intensity modulation signal memory (LPM) 32 that stores the light intensity modulation signal, and the processed color video signal. And a processed color video signal memory (PSM) 33 for storage.

  The gate driver 41 generates a gate signal based on various timing signals such as a gate clock signal (GCK) and a gate start pulse (GSP) transmitted from the timing controller 12 and transmits them to the gate signal line 63.

  Based on various timing signals such as a source clock signal (SCK) and a source start pulse (SSP) transmitted from the timing controller 12, the source driver 42 processes a processed color video signal (R ′S) transmitted from the data converter 16. , G ′S, B ′S), a source signal is generated and transmitted to the source signal line 64.

  That is, when an image is displayed on the liquid crystal display panel 61, the gate driver 41 and the source driver 42 operate as follows (note that the common electrode 68 includes a display controller (DCR) 11 not shown). The common voltage is applied by the common electrode voltage control unit).

  First, the gate driver 41 transmits a gate signal to each gate signal line 63, thereby sequentially turning on the TFTs 65 of each pixel. The source driver 42 transmits the source signal to the source signal line 64 in synchronization with the timing of transmission of the gate signal to each gate signal line 63 by the gate driver 41. Then, the potential difference between the pixel electrode 66 and the common electrode 68 changes according to the source signal, and the liquid crystal is modulated. As a result, the amount of light from the backlight unit 71 changes as it passes through the liquid crystal, and an image corresponding to the source signal is displayed on the liquid crystal display panel 61.

  The light source control unit (LCU) 51 is a circuit that controls the fluorescent tube 72, and includes a dimming pulse generator (ALP) 52, a pulse width modulation unit (PWMU) 53, and an inverter unit (IVTU) 55.

  The dimming pulse generator 52 includes a reference oscillator (not shown) that generates a reference oscillation clock, and generates a dimming pulse signal based on the clock.

  The pulse width modulation unit 53 includes a plurality of pulse width modulation units (PWM) 54 corresponding to each fluorescent tube 72. The pulse width modulation unit 54 receives the dimming pulse from the dimming pulse generation unit 52 and modulates the pulse width and period of the dimming pulse (note that the modulated dimming pulse signal is Also called PWM signal).

  The inverter unit 55 includes a plurality of inverters (IVTs) 56 corresponding to each fluorescent tube 72 and thus for each pulse width modulation unit 54. The inverter 56 adjusts the current supplied from the power source (not shown) based on the PWM signal generated by the pulse width modulation unit 54, and generates a light emission signal for controlling the light emission of the fluorescent tube 72, It transmits to the fluorescent tube 72. As a result, the light emission of the fluorescent tube 72 is controlled by the light source control unit 51.

  Here, the light emission control of the fluorescent tube 72 in the liquid crystal display device 81 equipped with various circuits as described above will be described in detail.

  First, the chromaticity of the fluorescent tubes 72R, 72G, 72B will be described. The chromaticity distribution (color triangular area) in the chromaticity diagram shown in FIG. 5 is obtained when the fluorescent tubes 72R, 72G, and 72B are lit with the same light intensity. Then, if all types of the fluorescent tubes 72R, 72G, and 72B do not emit light but emit light every two types, naturally, the chromaticity distribution is different from FIG. 6 to 8 show chromaticity distributions when the fluorescent tube 72 emits light every two types.

  Specifically, FIG. 6 is a chromaticity diagram when the fluorescent tube 72R does not emit light and the fluorescent tube 72G and the fluorescent tube 72B are lit with the same light intensity. Therefore, in FIG. 6, [−R] GB is attached to this graph line for convenience (note that the graph line in the chromaticity diagram is a broken line and the dot is a square). Further, the chromaticity of the vertex in the color triangle area, that is, the chromaticity of the vertex near RED, the chromaticity of the vertex near GREEN, and the chromaticity of the vertex near BLUE are expressed as (x [−R] r, y [ -R] r), (x [-R] g, y [-R] g), (x [-R] b, y [-R] b).

  FIG. 7 is a chromaticity diagram when the fluorescent tube 72G does not emit light and the fluorescent tube 72R and the fluorescent tube 72B are lit with the same light intensity. Therefore, in FIG. 7, for the sake of convenience, this graph line is given R [-G] B (note that the graph line in the chromaticity diagram is a one-dot chain line and the dot is a triangle). For convenience, the chromaticity of the vertex in the color triangle area, that is, the chromaticity of the vertex near RED, the chromaticity of the vertex near GREEN, and the chromaticity of the vertex near BLUE are (x [−G] r, y [ -G] r), (x [-G] g, y [-G] g), (x [-G] b, y [-G] b).

  FIG. 8 is a chromaticity diagram when the fluorescent tube 72B does not emit light and the fluorescent tube 72R and the fluorescent tube 72G are lit with the same light intensity. Therefore, in FIG. 8, RG [-B] is attached to this graph line for convenience (note that the graph line in the chromaticity diagram is a two-dot chain line, and the dot is a rhombus). Further, the chromaticity of the vertex in the color triangle area, that is, the chromaticity of the vertex near RED, the chromaticity of the vertex near GREEN, and the chromaticity of the vertex near BLUE are (x [−B] r, y [ -B] r), (x [-B] g, y [-B] g), (x [-B] b, y [-B] b).

The vertices of the color triangle area in FIGS. 6 to 8 can be expressed as follows.
When x [-R] r, x [-G] r, and x [-B] r are collectively referred to as xr '.
When x [-R] g, x [-G] g, and x [-B] g are collectively referred to as xg '.
When x [-R] b, x [-G] b, and x [-B] b are collectively referred to as xb '.
When y [-R] r, y [-G] r, and y [-B] r are collectively referred to as yr '.
When y [-R] g, y [-G] g, and y [-B] g are collectively referred to as yg '.
When y [-R] b, y [-G] b, and y [-B] b are collectively referred to as yb '.

  FIG. 9 is a chromaticity diagram that collectively illustrates FIGS. The following can be said from FIG.

  That is, the fluorescent tubes 72R, 72G, 72B have a broad spectrum distribution as shown in FIGS. 4A, 4B, and 4C. Therefore, even if not all types of fluorescent lamps 72R, 72G and 72B emit light, the chromaticity distribution when the fluorescent lamps 72G and 72B emit light (when the emission luminance of the fluorescent tube 72R is relatively low), the fluorescent lamp Chromaticity distribution when 72R and 72B emit light (when the emission luminance of the fluorescent tube 72G is relatively low), and chromaticity when the fluorescent light 72R and 72G emit light (when the emission luminance of the fluorescent tube 72B is relatively low) Even with the distribution, a chromaticity distribution similar to the chromaticity distribution when all the fluorescent lights 72R, 72G, 72B emit light is generated.

  Then, depending on the color video signals (RS, GS, BS) generated by the video signal processing unit (VSP), it is possible to cope with all types of fluorescent tubes 72R, 72G, 72B not emitting light. That is, if the chromaticity distribution calculated based on the color video signals (RS, GS, BS) is a relatively narrow chromaticity distribution, the fluorescent tube 72 that can reproduce the narrow chromaticity distribution only needs to emit light. (For example, if the signal intensity of the color video signal BS is extremely low, a small amount of light from the fluorescent tube 72B may be turned off).

  However, since all the fluorescent tubes 72 do not emit light (because some of the fluorescent tubes 72 emit relatively low luminance), the color video signals (RS, GS, BS) are processed in consideration of this, The processed color video signal (R ′S, G ′S, B ′S) is obtained. Such processing is desirable if the following relational expression is satisfied {note that Y in the Yxy chromaticity diagram is luminance (lightness)}.

* Relational expression (1)
(RS [i] × xr + GS [i] × xg + BS [i] × xb) / (RS [i] + GS [i] + BS [i])
= (R'S [i] * xr '+ G'S [i] * xg' + B'S [i] * xb ') / (R'S [i] + G'S [i] + B'S [i])
* Relational expression (2)
(RS [i] x yr + GS [i] x yg + BS [i] x yb) / (RS [i] + GS [i] + BS [i])
= (R'S [i] x yr '+ G'S [i] x yg' + B'S [i] x yb ') / (R'S [i] + G'S [i] + B'S [i])
* Related color (3)
(RS [i] * Yr + GS [i] * Yg + BS [i] * Yb) = (R'S [i] * Yr '+ G'S [i] * Yg' + B'S [i] * Yb ')

In addition,
RS [i] : Signal strength of red video signal RS
GS [i] : Signal strength of green video signal GS
BS [i] : Blue video signal BS signal strength
xr : Value of x in the red video signal RS in the Yxy chromaticity diagram
xg : Value of x in the green video signal GS in the Yxy chromaticity diagram
xb : Value of x in the blue video signal BS in the Yxy chromaticity diagram
yr : Value of y in the red video signal RS in the Yxy chromaticity diagram
yg : Value of y in the green video signal GS in the Yxy chromaticity diagram
yb : Value of y in the blue video signal BS in the Yxy chromaticity diagram
Yr : Y value in the red video signal RS in the Yxy chromaticity diagram
Yg : Y value in the green video signal GS in the Yxy chromaticity diagram
Yb : Y value in the blue video signal BS in the Yxy chromaticity diagram
R'S [i]: Signal strength of processed red video signal R'S
G'S [i]: Signal strength of processed green video signal G'S
B'S [i]: Signal intensity of processed blue video signal B'S
xr ′: the value of x in the processed red video signal R ′S in the Yxy chromaticity diagram
xg ′: x value in the processed green video signal G ′S in the Yxy chromaticity diagram
xb ′: the value of x in the processed blue video signal B ′S in the Yxy chromaticity diagram
yr ': the value of y in the processed red video signal R'S in the Yxy chromaticity diagram
yg ': the value of y in the processed green video signal G'S in the Yxy chromaticity diagram
yb ′: y value in the processed blue video signal B ′S in the Yxy chromaticity diagram
Yr ′: Y value in the processed red video signal R ′S in the Yxy chromaticity diagram
Yg ': Y value in the processed green video signal G'S in the Yxy chromaticity diagram
Yb ′: Y value in the processed blue video signal B ′S in the Yxy chromaticity diagram.

  However, in reality, there are cases where the related colors (1) to (3) are not satisfied. This is because, for example, R ′S [i], G ′S [i], and B ′S [i] show a negative value or a situation exceeding full gradation occurs. In addition, there are numerous calculation cases based on such relational expressions (1) to (3). Therefore, the signal strengths (R ′S [i], G ′S [i], B ′S [i]) of the processed color video signals (R ′S, G ′S, B ′S) are calculated in advance and stored in the nonvolatile memory 31. ing.

In addition, since the memory capacity of the nonvolatile memory 31 is also limited, it is difficult to store a large amount of light intensity signal data in the light intensity signal memory 32. Therefore, for example, fluorescent tubes 72R, 72G, in each 72B, the light intensity large, the light intensity small, set to two stages, the fluorescent tubes 72R, 72G, 8 pattern derived by a combination of 72B ^{(2 3} patterns) may store the pattern data of the light intensity modulation signal {However, not limited to this, the light intensity large, in the light intensity, the light intensity modulation signal of light intensity is small, 27 patterns derived from three stages (3 ³ patterns) May also be stored}.

  Based on the above, the liquid crystal display device 81 adjusts the light intensity of the fluorescent tube 72 in accordance with the video signal that is the basis of the image (controls the light emission of the fluorescent tube 72), and further, the color video included in the video signal The signal is processed in accordance with the light intensity of the fluorescent tube 72 to modulate the color of the image. Therefore, the process of such color modulation will be described in detail with reference to FIG.

  First, the video signal processing unit 21 in the liquid crystal display device 81 receives a video signal. Then, the video signal processing unit 21 processes the video color signal to generate a color video signal and a synchronization signal related to the color video signal [video signal processing step]. Further, the video signal processing unit 21 transmits the color video signal and the synchronization signal to the display controller 11.

  The display controller 11 receives the color video signal and the synchronization signal transmitted from the video signal processing unit 21. More specifically, the timing controller 12 in the display controller 11 receives the synchronization signal, and the frame data monitoring unit 13 receives the color video signal.

  The color video signal is first received by the frame memory 14 of the frame data monitoring unit 13, and the frame memory 14 receives one frame based on the timing signal indicating the start and end of one frame transmitted from the timing controller 12. One color video signal is stored [1-frame color video signal storage step]. Then, the color image signal for one frame is transmitted to the chromaticity distribution calculation unit 15 by the frame memory 14.

  The chromaticity distribution calculation unit 15 calculates chromaticity distribution data from the received color video signal for one frame. That is, chromaticity distribution data is calculated by calculating chromaticity from each color video signal constituting one frame and mapping the chromaticity data [chromaticity calculation step]. Then, the chromaticity distribution calculation unit 15 transmits the calculated chromaticity distribution data to the data conversion unit 16.

  The data conversion unit 16 acquires a light intensity modulation signal of the fluorescent tube 72 required for reproducing the received chromaticity distribution data. More specifically, the data conversion unit 16 acquires pattern data of a light intensity modulation signal stored in the light intensity signal memory 32 of the nonvolatile memory 31.

This pattern data is data indicating what kind of chromaticity distribution is generated by the fluorescent tube 72 that emits light. For example, fluorescent tubes 72R, 72G, in each 72B, the light intensity large, the light intensity small, set to two stages, the light intensity of the fluorescent tubes 72R, 72G, 8 pattern derived by a combination of 72B ^{(2 3} patterns) When the signal pattern data is recorded, the data conversion unit 16 acquires one pattern data capable of reproducing the received chromaticity distribution data from the eight pattern data [light intensity modulation signal acquisition step].

  Further, the data conversion unit 16 acquires a processed color video signal corresponding to the acquired pattern data. The processed color video signal is as follows in detail. That is, when the light from the fluorescent tube 72 based on the determined pattern data is emitted through the color filter 69, the color video signal is processed so as to have a color assumed in the color video signal.

  In short, if the pattern data is such that all types of fluorescent tubes 72 emit light, the color image signal based on the light emission of all types of fluorescent tubes 72 is desired by the light of some types of fluorescent tubes 72. The color cannot be reproduced. Therefore, in order to reproduce a color as close as possible to the desired color (in order to modulate the color of an undesired image to the color of the desired image), a signal based on the light emission of some types of fluorescent tubes 72 is required. Become. The signal is a processed color video signal obtained by processing the color video signal.

  The processed color video signal is preferably processed in accordance with each gradation in the range from zero gradation to full gradation in order to display an image rich in gradation. However, the processing burden is very heavy. Therefore, the processed color video signal is calculated in advance and stored in the processed color video signal memory 33. Therefore, the data conversion unit 16 acquires the processed color video signal stored in the processed color video signal memory 33 according to the acquired pattern data. That is, the data conversion unit 16 acquires a processed color video signal required for color modulation of an image corresponding to the pattern data (light intensity modulation signal) [processed color video signal acquisition step].

  As described above, the data conversion unit 16 acquires the pattern data and the processed color video signal. In summary, the display controller 11 receives the video signal that is the basis of the image, calculates the chromaticity from the color video signal in the video signal, and corresponds to the chromaticity, and the light of some of the fluorescent tubes 72. A light intensity modulation signal (pattern data) for reducing the intensity below the light intensity of the remaining fluorescent tubes 72 is acquired. Further, the display controller 11 acquires a processed color video signal (a signal obtained by processing the color video signal) required for color modulation of the image in correspondence with the pattern data.

  The display controller 11 (more specifically, the data conversion unit 16) transmits the pattern data to the light source control unit 51 and transmits the processed color video signal to the source driver 42.

  The light source control unit 51 receives a lighting timing signal from the timing controller 12 in addition to the pattern data. More specifically, the pulse width modulation unit 53 of the light source control unit 51 receives the pattern data and the lighting timing signal, and further receives the dimming pulse signal from the dimming pulse generation 52. Then, the pulse width modulation unit 53 modulates the dimming pulse signal based on the pattern data and the lighting timing signal to obtain a PWM signal [PWM signal generation step].

  Then, the pulse width modulation unit 53 transmits the PWM signal to the inverter unit 55, and the inverter unit 55 adjusts the current supplied from the power source (not shown) based on the PWM signal, and emits light from the fluorescent tube 72. A light emission signal for controlling the light is generated [light emission signal purification step]. The fluorescent tube 72 emits light based on this light emission signal.

  On the other hand, the source driver 42 receives various timing signals from the timing controller 12 in addition to the processed color video signal. Then, the source driver 42 samples the processed color video signal transmitted from the data converter 16 based on the various timing signals, and generates a source signal. Thereafter, the source driver 42 transmits the source signal to the source signal line in accordance with the timing of transmission of the gate signal to each gate signal line 63 by the gate driver 41.

  As a result, by connecting to the drain of the TFT 65, the potential difference between the pixel electrode 66 that has received the source signal and the common electrode 68 changes according to the source signal, thereby modulating the liquid crystal. Therefore, an image corresponding to the source signal is displayed on the liquid crystal display panel 61.

  In the liquid crystal display device 81 that has undergone the above process, the display controller 11 may not cause all types of fluorescent tubes 72 to emit light with the same light intensity in accordance with the video signal. For example, depending on the video signal, the fluorescent tubes 72G and 72B may be turned on and the fluorescent tube 72R may be turned off. In such a case, power consumption is suppressed compared to the case where all types of fluorescent tubes 72R, 72G, 72B are lit. That is, in the liquid crystal display device 81, low power consumption is achieved.

  It should be noted that the desired color reproduction is almost possible even by such light emission control of the fluorescent tube 72. Unlike the LED, the fluorescent tube 72 has a relatively broad spectral distribution and further has a luminous efficiency. This is because it is expensive. In addition, since the fluorescent tube 72 is less expensive than the LED, the cost of the backlight unit 71 and thus the liquid crystal display device 81 can be reduced.

[Other embodiments]
The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

  For example, in the liquid crystal display device 81 described above, the data conversion unit 16 of the display controller 11 acquires the light intensity modulation signal data (pattern data) of the fluorescent tube 72 and the processed color video signal from the nonvolatile memory 31. However, it is not limited to this. For example, when the data conversion unit 16 acquires a color video signal, the data conversion unit 16 acquires the color video signal by generating pattern data corresponding to the color video signal, and further processes the color video signal corresponding to the pattern data. Then, a processed color video signal may be acquired.

  The backlight unit 71 was equipped with a red fluorescent tube 72R, a green fluorescent tube 72G, and a blue fluorescent tube 72B. However, the emission color is not limited to this. In short, it is not particularly limited as long as it is a luminescent color capable of generating white color by mixing colors.

  By the way, the liquid crystal display panel 61 includes a red color filter 69, a green color filter 69, and a blue color filter 69. The light from the backlight unit 71 passes through these color filters 69. Therefore, the spectral characteristic of the red color filter 69 and the spectral characteristic of the red fluorescent tube 72R are approximated, and the spectral characteristic of the green color filter 69 and the spectral characteristic of the green fluorescent tube 72G are approximated. It is desirable that the spectral characteristics of the above and the spectral characteristics of the fluorescent tube 72B emitting blue light approximate.

  In this case, when the red light from the fluorescent tube 72R passes through the red color filter 69R, when the green light from the fluorescent tube 72G passes through the green color filter 69R, the blue light from the fluorescent tube 72B is When the light passes through the blue color filter 69R, the amount of light absorbed by the color filters 69R, 69G, and 69B is small. In addition, the difference in chromaticity is relatively small between the light from the fluorescent tubes 72R, 72G, and 72B and the light that has passed through the color filters 69R, 69G, and 69B. Therefore, color modulation in the liquid crystal display device 81 is relatively easy.

  As an example of approximating the spectral characteristics (transmission spectral characteristics) of the color filters 69R, 69G, 69B and the spectral characteristics of the fluorescent tubes 72R, 72G, 72B, a phosphor is applied to the glass tube of the fluorescent tube 72. In addition, it is possible to include colored particles that approximate the spectral characteristics of the color filter 69 in the glass bottle (in short, a colored glass tube coated with a phosphor may be used).

  In the liquid crystal display device 81 described above, a diffusion sheet 73 that diffuses light is interposed between the liquid crystal display panel 61 and the backlight unit 71. The distance between the diffusion sheet 73 and the fluorescent tube 72 is desirably as wide as possible. More specifically, the interval between the diffusion sheet 73 and the fluorescent tube 72 may be an interval in which the width of the light flux diverging from the fluorescent tube 72 and the width of the diffusion sheet 73 are matched.

  With this configuration, a relatively wide light beam (for example, a light beam wider than the LED) that diverges from the fluorescent tube 72 enters the entire diffusion sheet 73, and the light is uniformly diffused by the diffusion sheet 73. . Therefore, the light emitted from the diffusion sheet 73 has a relatively high uniformity.

  In addition, with such a liquid crystal display device 81, the number of fluorescent tubes 72 is also reduced, and the cost of the backlight unit 71, and thus the liquid crystal display device 81, is also suppressed (such a liquid crystal display device). It can be said that the display device 81 reduces the number of fluorescent tubes 72 regardless of the light emission control of the fluorescent tubes 72 described above).

  Incidentally, the display control (color modulation) in the liquid crystal display device 81 described above is realized by a control program. Therefore, the liquid crystal display 81 includes, for example, a CPU (central processing unit) that executes instructions of a control program that realizes various functions, a ROM (read only memory) that stores the control program, and a RAM (random access) that expands the control program. memory), a storage device (recording medium) such as a memory for storing the control program and various data.

  The control program may be recorded on a computer-readable recording medium. This is because the program recorded on the recording medium becomes portable.

  Examples of the recording medium include a tape system such as a magnetic tape and a cassette tape to be separated, a disk system of an optical disk such as a magnetic disk and a CD-ROM, a card system such as an IC card (including a memory card) and an optical card. Or a semiconductor memory system such as a flash memory.

  Further, the liquid crystal display device 81 may acquire the control program through communication from a communication network. The communication network includes the Internet, infrared communication, etc. regardless of wired wireless.

These are block diagrams which show the various circuits contained in a liquid crystal display device. FIG. 3 is an exploded perspective view of a liquid crystal display device. FIG. 4 is a spectral characteristic diagram of a red color filter, a green color filter, and a blue color filter. (A) is a spectrum diagram of a fluorescent tube emitting red light, (B) is a spectrum diagram of a fluorescent tube emitting green light, (C) is a spectrum diagram of a fluorescent tube emitting blue light, and (D) These are the spectrum figures which illustrated (A)-(C) collectively. These are chromaticity diagrams of the CIE Yxy system. These are chromaticity diagrams showing the chromaticity distribution produced by green light and blue light in the CIE Yxy system. These are chromaticity diagrams showing the chromaticity distribution produced by red light and blue light in the CIE Yxy system. These are chromaticity diagrams showing the chromaticity distribution caused by red light and green light in the CIE Yxy system. FIG. 5 is a CIE Yxy chromaticity diagram illustrating FIGS. 5 to 8 collectively. These are sectional drawings of the conventional liquid crystal display device. These are the spectrum figures of the fluorescent tube which emits white light. FIG. 3 is a spectrum diagram of a red light emitting LED, a green light emitting LED, and a blue light emitting LED.

Explanation of symbols

11 Display controller (display controller)
12 Timing controller 13 Frame data monitoring unit 14 Frame memory 15 Chromaticity distribution calculation unit 16 Data conversion unit 21 Video signal processing unit 31 Non-volatile memory (storage unit)
32 Light intensity signal memory 33 Processed color video signal memory 41 Gate driver 42 Source driver 51 Light source control unit 52 Dimming pulse generation unit 53 Pulse width modulation unit 54 Pulse width modulation unit 55 Inverter unit 56 Inverter 61 Liquid crystal display panel 62 Active matrix substrate 63 Gate signal line 64 Source signal line 65 TFT
66 pixel electrode 67 counter substrate 68 common electrode 69 color filter 71 backlight unit 72 fluorescent tube (linear light source)
73 Diffusion sheet 74 Housing 81 Liquid crystal display device

Claims (8)

A liquid crystal display panel for displaying images;
A backlight unit that has a plurality of linear light sources that emit different colors, generates white color by mixing colors, and irradiates the liquid crystal display panel;
The video signal that is the basis of the above image is received, the chromaticity is calculated from the color video signal in the video signal, and the light intensity of some of the linear light sources is adjusted to correspond to the chromaticity. Display that acquires a light intensity modulation signal for lowering the light intensity of the linear light source, and further acquires a processed color video signal that processes the color video signal corresponding to the light intensity modulation signal. A control unit;
Including a liquid crystal display device. A storage unit for storing the light intensity modulation signal and the processed color video signal;
The liquid crystal display device according to claim 1, wherein the display control unit acquires the light intensity modulation signal and the processed color video signal from the storage unit without acquiring the light intensity modulation signal and the processed color video signal by generation.   The liquid crystal display device according to claim 1, wherein the backlight unit includes a linear light source that emits red light, a linear light source that emits green light, and a linear light source that emits blue light. The liquid crystal display panel includes a red color filter, a green color filter, and a blue color filter.
The spectral characteristics of the red color filter approximate the spectral characteristics of the linear light source emitting red light, and the spectral characteristics of the green color filter approximate to the spectral characteristics of the linear light source emitting green light. The liquid crystal display device according to claim 3, wherein the spectral characteristics of the light source emitting linear blue light are approximate. Between the liquid crystal display panel and the backlight unit, a diffusion sheet that diffuses light is interposed,
5. The liquid crystal display according to claim 1, wherein an interval between the diffusion sheet and the light source is an interval that matches a width of a light beam diverging and spreading from the linear light source and a width of the diffusion sheet. apparatus. A liquid crystal display panel for displaying images;
A backlight unit that has a plurality of linear light sources that emit different colors, generates white color by mixing colors, and irradiates the liquid crystal display panel;
A color modulation method in a liquid crystal display device including:
A chromaticity calculation step of receiving a video signal that is the basis of the image and calculating a chromaticity from the color video signal in the video signal;
A light intensity modulation signal acquisition step for acquiring a light intensity modulation signal for reducing the light intensity of some of the linear light sources below the light intensity of the remaining linear light sources in correspondence with the chromaticity;
A processing initial video signal acquisition step of acquiring a processed color video signal that processes the color video signal in correspondence with the light intensity modulation signal;
Including a liquid crystal display device. A liquid crystal display panel for displaying images;
A backlight unit that has a plurality of linear light sources that emit different colors, generates white color by mixing colors, and irradiates the liquid crystal display panel;
A display control unit for controlling the image of the liquid crystal display panel and the amount of light of the backlight unit;
A color modulation program for a liquid crystal display device including:
The video signal that is the basis of the above image is received, the chromaticity is calculated from the color video signal in the video signal, and the light intensity of some of the linear light sources is adjusted to correspond to the chromaticity. Display that acquires a light intensity modulation signal for lowering the light intensity of the linear light source, and further acquires a processed color video signal that processes the color video signal corresponding to the light intensity modulation signal. A color modulation program that causes the display control unit to execute control.   A computer-readable recording medium in which the color modulation program according to claim 7 is recorded.

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