JP2007114480A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable production of peak luminance in field sequential driving of ≥4 colors of a liquid crystal display device. <P>SOLUTION: In the liquid crystal display device 100, a controller 37 lights only the LED of R (red) of a back light 10 via an LED driving section 9 to perform display of an LCD panel 41, then lights only the LED of G (green) of the back light 10 to perform display of the LCD panel 41, lights only the LED of B (blue) of the back light 10 to perform display of the LCD panel 41, and lights all the LEDs of R, G, B of the back light 10 to perform display of the LCD panel 41. At this time, the controller 37 calculates the display data as R=R, G=G, B=B, W=R<SP>2</SP>G<SP>2</SP>B<SP>2</SP>. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device used for a liquid crystal television, an in-vehicle navigation system monitor, an OA liquid crystal monitor, a mobile monitor, and the like.

  Conventionally, a TN liquid crystal display element has been generally used as the liquid crystal display element.

  An OCB type display element has been studied as a liquid crystal display element characterized by high-speed response (for example, Non-Patent Document 1). This OCB type liquid crystal display element has an advantage of a high response speed, and can be expected to be applied to a field sequential type display device. In this field sequential display device, R (red), G (green), and B (blue) light sources are separately formed in a backlight, and each color is sequentially lit in time series, and according to the display color. The video is displayed on the liquid crystal panel. Therefore, a display device that does not require a color filter, is inexpensive, bright, and has low power consumption can be provided.

However, this field sequential type display device has a problem of “color breakup” that appears instantaneously in rainbow colors due to the movement of the line of sight and the blurring of the screen. To alleviate this, instead of the conventional three-color display of R, G, B, four-color display of R, G, B, W (white), or R, G, B, C (cyan), M ( Magenta) and Y (yellow) have been proposed (for example, Non-Patent Document 2 and Patent Document 1).
The Institute of Electrical Communication IEICE Technical Report EDI 98-144, page 199 2003 SID (Society for Information Display) Proceedings 1212-1215 JP 2003-280614 A

  By the way, in a CRT display device that has been used for many years as a display, if there is a locally bright part on a dark screen, the display power tends to concentrate and shine strongly. This phenomenon is desirable for an image with a sharp edge. On the other hand, in general, a liquid crystal display device has a problem that it is difficult to provide a beam and peak luminance does not occur.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid crystal display device capable of providing peak luminance with a sharp beam in field sequential driving of four or more colors.

  According to the present invention, the liquid crystal display panel includes a plurality of color light sources and a liquid crystal display panel, and the liquid crystal display panel performs display corresponding to the lighting color in synchronization with the light sources of the plurality of colors sequentially lighting. A field sequential type liquid crystal display device that performs color display corresponding to input data of a plurality of colors having a luminance correction period in which light sources of a plurality of colors emit light, and the display data displayed in the luminance correction period is the luminance There is provided a liquid crystal display device that is calculated approximately equal to the product of the power of the input data of the plurality of colors corresponding to the light sources of the plurality of colors that emit light during the correction period.

  In addition, according to the present invention, the liquid crystal display panel includes a plurality of light sources and a liquid crystal display panel, and the liquid crystal display panel performs display corresponding to the lighting color in synchronization with the light sources of the plurality of colors being sequentially turned on. A field-sequential type liquid crystal display device that performs color display corresponding to input data of a plurality of colors, with respect to the input data of the plurality of colors so as to increase white brightness rather than a single color while maintaining the color purity of the single color. Thus, there is provided a liquid crystal display device that converts display data corresponding to the number of fields.

  The liquid crystal display device of the present invention makes it possible to produce peak luminance with a sharp beam and to prevent color breakup by field sequential driving of four or more colors.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 schematically shows a circuit configuration of the liquid crystal display device 100.

  The liquid crystal display device 100 is connected to an image information processing unit SG serving as an external signal source. The image information processing unit SG performs image information processing and supplies a synchronization signal and a display signal to the liquid crystal display device 100. The power supply voltage of the liquid crystal display device is also supplied to the liquid crystal display device 100 from the image information processing unit SG.

  The liquid crystal display device 100 includes an LCD panel 41 that forms a matrix array (liquid crystal display element section) of a plurality of OCB liquid crystal display elements 6, and a backlight 10 that includes a plurality of R, G, and B LEDs that illuminate the LCD panel 41. And a drive circuit DR for driving the LCD panel 41 and the backlight 10. The LCD panel 41 includes an array substrate AR, a counter substrate CT, and a liquid crystal layer LQ.

  In the array substrate AR, the plurality of pixel electrodes 15 are arranged in a substantially matrix shape on the transparent insulating substrate GL. A plurality of gate lines 29 (Y1 to Ym) are arranged along the rows of the plurality of pixel electrodes 15, and a plurality of source lines 26 (X1 to Xn) are arranged along the columns of the plurality of pixel electrodes 15. . A plurality of pixel switches 27 are arranged in the vicinity of the intersection position of the gate line 29 and the source line 26. Each pixel switch 27 includes, for example, a thin film transistor having a gate 28 connected to the gate line 29 and a source-drain path connected between the source line 26 and the pixel electrode 15, and is driven through the corresponding gate line 29. Are connected between the corresponding source line 26 and the corresponding pixel electrode 15.

  Each of the plurality of OCB liquid crystal display elements 6 has a liquid crystal capacitance Clc between the pixel electrode 15 and the counter electrode 16. Each of the plurality of auxiliary capacitance lines Cst (C1 to Cm) is capacitively coupled to the pixel electrode 15 of the OCB liquid crystal display element 6 in the corresponding row to constitute an auxiliary capacitance Cs.

  The drive circuit DR is configured to control the transmittance of the LCD panel 41 by a liquid crystal application voltage applied to the liquid crystal layer LQ from the array substrate AR and the counter substrate CT. Each OCB liquid crystal display element 6 constitutes a pixel in the range of the corresponding pixel electrode 15. In such an OCB liquid crystal display element 6, it is necessary to transfer the alignment state of liquid crystal molecules from a splay alignment to a bend alignment capable of displaying an image by applying a transition voltage different from a normal driving voltage. Therefore, the driving circuit DR initializes the transition state of the liquid crystal molecules from the splay alignment to the bend alignment by applying a transition voltage to the liquid crystal layer LQ as a liquid crystal application voltage every time a power switch (not shown) is turned on. Is configured to do.

  Specifically, the drive circuit DR sequentially drives the plurality of gate lines 29 so that the plurality of pixel switches 27 are conducted in units of rows, and the pixel switches 27 in each row are conducted by driving the corresponding gate lines 29. A backlight composed of a source driver 38 for outputting the pixel voltage Vs to the plurality of source lines 26 during the period of time, a counter electrode driver 40 for driving the counter electrode 16 of the LCD panel 41, and a plurality of LEDs of R, G, B. Power supplied to the drive circuit DR from the image information processing unit SG, and the LED drive unit 9 that drives 10, the gate driver 39, the source driver 38, the counter electrode driver 40, and the controller 37 that controls the LED drive unit 9. The gate driver 39, the source driver 38, the counter electrode gate A power supply circuit 7 that generates a plurality of internal power supply voltages required for the driver 40, the LED drive unit 9, and the controller 37 is provided.

  The controller 37 outputs a vertical timing control signal generated based on the synchronization signal input from the image information processing unit SG to the gate driver 39, and based on the synchronization signal and display signal input from the image information processing unit SG. The generated horizontal timing control signal and pixel data for one horizontal line are output to the source driver 38, and a lighting control signal is output to the LED drive unit 9. The gate driver 39 sequentially selects a plurality of gate lines 29 in one frame period under the control of the vertical timing control signal, and outputs a gate drive voltage for making the pixel switches 27 in each row conductive for one horizontal scanning period H to the selection gate line 29. . The source driver 38 converts the pixel data for one horizontal line into a pixel voltage (display voltage) Vs in one horizontal scanning period H in which the gate drive voltage is output to the selection gate line 29 under the control of the horizontal timing control signal. Are output to the source line 26 in parallel.

  Next, the operation of the liquid crystal display device 100 by the controller 37 in such a configuration will be described.

  FIG. 2 shows the concept of conventional field sequential driving. The backlight 10 composed of a plurality of LEDs of R, G, and B is turned on sequentially in the order of R (red) → G (green) → B (blue) → R (red), and in accordance with the timing. Color display is performed by displaying on the LCD panel 41 corresponding to the colors. The simple field sequential drive has three colors of R, G, and B, but is driven with four colors including W (white) in order to prevent color breakup.

  FIG. 3 shows the concept of four-color field sequential driving used in the present invention. In the figure, the controller 37 controls the LED drive unit 9 to turn on only the R (red) LED of the backlight 10 to display the letter A to be displayed in red on the LCD panel 41, and subsequently to the G of the backlight 10. Only the green LED is turned on to display the letter B for green display on the LCD panel 41. Subsequently, only the B (blue) LED of the backlight 10 is turned on to display the letter C for blue display on the LCD panel 41. Then, all the R, G, and B LEDs of the backlight 10 are turned on, and the character W to be displayed in white on the LCD panel 41 is displayed. Thus, as shown in the lower part of FIG. 3, color display of red character A, green character B, blue character C, and white character W is realized.

  In the W (white) period, since all the LEDs of R, G, and B are lit, the brightness of the W field can be increased.

  When all the LEDs are displayed in all fields, the brightness can be increased by about 1.5 times. In the case of the three-color type, since it emits a single color in one third period, if 1/3 + 1/3 + 1/3 = 1, in the case of the four-color type, it emits light in a quarter period. 1/4 + 1/4 + 1/4 + 3/4 = 6/4. That is, in the case of the four-color type, the ratio becomes 6/4 because the last frame (W field) lights all three-color LEDs.

  For this reason, the brightness when white is displayed can be increased by a factor of 1.5. That is, the W field is a luminance correction period in which the luminance is corrected and strengthened.

  However, there is a problem with this method. For example, when a single color R is displayed, 1/3 + 0/3 + 0/3 = 1/3 for the three-color type, but 1/4 + 0/4 + 0/4 + 0/4 for the four-color type. = 1/4, which is rather darker than the three-color type.

  If the W period is lit, the brightness increases but the color purity deteriorates. Therefore, inventiveness is required for a method of converting input data for increasing the brightness of white while maintaining color purity into data of R, G, B, and W.

  In the present invention, when calculating the display data from the input data, the controller 37 uses a power of the product of the input data for calculating the W display data in addition to the R, G, and B display data.

  To simplify the description of the invention, FIG. 4 shows a virtual two-color display.

  Here, there are x color and y color, and a thick dotted line area shown in FIG. 5 indicates a color range that can be expressed. The three vectors represented here are “x”, “y”, and “z” when x and y are lit simultaneously.

In the liquid crystal display device 100 of the present invention, luminance correction data to be displayed in a color period in which a plurality of LEDs are lit, such as z = x ⁿ y ⁿ , is displayed as a product of the power of the corresponding color element. Here, the display color elements x and y are each normalized between 0 and 1.

  A range indicated by a thick solid line shown in FIG. 6 is an x and y region having no z component.

In FIG. 7, as indicated by z = x ² y ² according to the concept of the present invention, the square region (thin dotted line) is deformed into a shape that is extended only in the diagonal direction. However, the coordinates of the pure color (x, 0) (0, y) do not change. Further, when white display is performed (x = 1, y = 1), (2, 2) is obtained, and the maximum luminance can be displayed.

  The present invention is not limited to n = 2. However, when n = 1, the color purity shift is large, and when n = 4 or more, the brightness near the halftone is low, so n = 2-4, preferably n = 2-3.

  Here, n need not be an integer.

  Further, the field sequential backlight is not limited to the LED, but may be a fluorescent tube.

  Next, the first embodiment will be described.

In the four-color field sequential drive shown in FIG. 3, when (R, G, B) data is input, the display data calculated by the controller 37 is
R = R
G = G
B = B
W = R ² G ² B ²
And

  At this time, when each of R, G, and B emits a single color, the brightness of white display can be maximized while maintaining the color purity. In this way, only the white peak can be intensely illuminated, and an effect of increasing the peak luminance in a pseudo manner can be obtained.

  As described above, according to the first embodiment, it is possible to realize the peak luminance that has been considered difficult in the liquid crystal display. In this case, since it is a four-color field sequential, the problem of color breakup is reduced.

  Next, a second embodiment will be described.

  Further, the present invention can be applied to R, G, B, C, M, Y type field sequential. This sequentially turns on R, G, B, G + B, B + R, and R + G, respectively.

At this time, similarly, when the data (R, G, B) is input, the display data calculated by the controller 37 is
R = R
G = G
B = B
C = G ² B ²
M = R ² B ²
Y = R ² G ²
And

  As described above, according to the second embodiment, the brightness can be achieved 1.5 times as described below while color breakup is suppressed almost completely.

1/6 + 1/6 + 1/6 + 2/6 + 2/6 + 2/6 = 9/6
Next, a third embodiment will be described.

  Furthermore, the present invention can be applied to R, G, B, C, M, Y, and W type field sequential. This sequentially lights R, G, B, G + B, B + R, R + G, and R + G + B, respectively.

At this time, similarly, when the data (R, G, B) is input, the display data calculated by the controller 37 is
R = R
G = G
B = B
C ⁼ G ^{2 B} 2
M = R ² B ²
Y = R ² G ²
W = R ² G ² B ²
And

  As described above, according to the third embodiment, the brightness can be doubled as follows while color breakup is suppressed almost completely.

1/7 + 1/7 + 1/7 + 2/7 + 2/7 + 2/7 + 3/7 = 12/6
The present invention is not limited to n = 2, but is arbitrary.

  The correction data need not be strictly a power, and correction data may be generated according to a substantially parabola.

  Further, the ratio of R, G, and B relating to the correction data may be equivalent as in this embodiment, or may be multiplied by a coefficient that emphasizes G, for example. For example, when correcting visibility, a coefficient should be applied before the correction term. It is a design matter.

  The present invention is also characterized in that the correction term can be calculated by a simple calculation.

  Further, the field sequential type liquid crystal of the present invention is not limited to the configuration as shown in FIG. 3, and the display data is changed in accordance with the color of the backlight 10 for each block as shown in FIG. The color scanning type field sequential may be changed.

  In the case of the color scanning type field sequential, it may be possible to turn off the light and turn on another color like R → G → B, but further R → Y → G → C → B → M → R. As described above, a six-color color scanning field sequential method in which the intermediate color is sandwiched between the RGB colors may be used. In this case, there is an advantage that the influence of color mixing due to the afterglow of the LED and the fluorescent tube can be minimized.

  As described above, according to the embodiment of the present invention, it is possible to achieve both monochrome color purity, white luminance, and prevention of color breakup by field sequential driving of four or more colors.

1 is a block diagram schematically showing a circuit configuration of a liquid crystal display device. The figure which shows the concept of the conventional field sequential drive. The figure which shows the concept of the four-color field sequential drive used by this invention. The figure which shows the virtual two-color display for demonstrating the principle of this invention. The figure which shows the displayable area | region in the principle of this invention. The figure which shows the input data for demonstrating the principle of this invention. The figure which shows the data after correction | amendment for demonstrating the principle of this invention. The figure for demonstrating a color scanning type | mold field sequential.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 6 ... OCB liquid crystal display element, 7 ... Power supply circuit, 9 ... LED drive part, 10 ... Back light, 15 ... Pixel electrode, 16 ... Counter electrode, 26 ... Source line, 27 ... Pixel switch, 28 ... Gate, 29 ... Gate Line 37, controller 38, source driver 39 39 gate driver 40 counter electrode driver 41 LCD panel 100 liquid crystal display device

Claims (7)

  A plurality of color light sources and a liquid crystal display panel are provided, and the liquid crystal display panel performs display corresponding to the lighting color in synchronization with the sequential lighting of the plurality of color light sources, thereby supporting input data of a plurality of colors. A field sequential type liquid crystal display device for performing color display, having a luminance correction period in which light sources of a plurality of colors emit light, and display data displayed in the luminance correction period is emitted in the luminance correction period. A liquid crystal display device, wherein the liquid crystal display device is calculated approximately equal to a product of powers of the input data of the plurality of colors corresponding to the light sources of the plurality of colors.   2. The liquid crystal display device according to claim 1, wherein the power multiplier is 2 or more and 4 or less.   2. The liquid crystal display device according to claim 1, wherein the power multiplier is 2 or more and 3 or less.   2. The liquid crystal display device according to claim 1, wherein the light sources of the plurality of colors are three colors of red, green, and blue, and the luminance correction period is a white period in which red, green, and blue are turned on simultaneously.   The light sources of the plurality of colors are three colors of red, green, and blue, and the luminance correction period includes a Y period in which red and green are lit, a C period in which green and blue are lit, and an M period in which blue and red are lit. The liquid crystal display device according to claim 1, wherein:   The light sources of the plurality of colors are three colors of red, green, and blue, and the luminance correction period is a Y period in which red and green are lit, a C period in which green and blue are lit, and an M period in which blue and red are lit. 2. The liquid crystal display device according to claim 1, wherein the period is a W period in which red, green, and blue are lit.   A plurality of color light sources and a liquid crystal display panel are provided, and the liquid crystal display panel performs display corresponding to the lighting color in synchronization with the sequential lighting of the plurality of color light sources, thereby supporting input data of a plurality of colors. A field-sequential liquid crystal display device that performs color display and displays the input data of the plurality of colors according to the number of fields so that the brightness of white is stronger than that of a single color while maintaining the color purity of the single color. A liquid crystal display device characterized by converting into data.

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