JP5273391B2 - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correctly perform AC driving on a display panel in a display device of a field sequential system, which also uses a color filter system. <P>SOLUTION: The display panel in which switch elements are separately arranged at right and left sides of a data signal line, and in which switch elements are separately arranged at upper and lower sides of a scan line is used. A means for performing AC driving with two sub-pixel periods on the display panel is provided. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device that displays images by a field sequential method.

  As a method for performing color display in a display device that displays an image using a liquid crystal display panel or the like, a color filter method and a field sequential method are known. The color filter method is a method for realizing color display by providing a color filter that selectively transmits a specific color (for example, three colors of red, green, and blue) for each pixel of the display device.

  On the other hand, in the field sequential method, color display is performed by sequentially switching and displaying images of a plurality of colors (for example, three colors of red, green, and blue) instead of using a color filter. If the images are switched at a sufficiently high speed, the human eye perceives them as a full color image in which the colors of these images are synthesized. Further, Patent Document 1 and Patent Document 2 propose a method of using a color filter together in the field sequential method.

  Further, in a liquid crystal display panel or the like, AC driving is used in order to avoid the occurrence of image sticking due to the bias of the voltage applied to the pixels. One of the AC drive methods is a staggered configuration in which odd-numbered and even-numbered columns of pixels are alternately connected to the data signal lines for each scanning signal line. A method for reducing electric power has been proposed (Patent Document 3).

JP-T-2006-501513 JP 2005-346042 A JP-A-9-16132

  In a field sequential type liquid crystal display device, when a conventional color filter type liquid crystal display panel is used as a display panel, the voltage held in the pixels of the liquid crystal display panel during inversion driving may be biased depending on the display image. This causes image quality degradation such as horizontal stripes, and causes burn-in.

  In the field sequential method, since each color image is displayed in a time-sharing manner, when three types of pixels (for example, three colors of red, green, and blue) are used, driving at a refresh rate of three times is required. Become. However, when the refresh rate of the liquid crystal display panel is increased, the time for supplying a video signal per pixel of the liquid crystal display panel (hereinafter referred to as “writing time”) is shortened. As a result, it becomes impossible to secure a sufficient time for the video signal to follow the original video signal, so that a sufficient potential is not held in the pixel electrode (hereinafter referred to as “writing shortage”), and the display on the display panel Is different from the original video signal. As a result, image quality degradation such as luminance reduction occurs.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to perform inversion driving with sufficient image quality in a field sequential display device using a color filter.

  The liquid crystal display device of the present invention includes a liquid crystal display panel that controls the orientation of a liquid crystal composition, and a backlight that alternately irradiates the liquid crystal display panel with first backlight light and second backlight light that are different colors of light. The liquid crystal display panel includes a first pixel composed of two adjacent sub-pixels each having a different color filter, and two adjacent ones adjacent to the first pixel and each having the different color filter. A potential difference between a high-potential-side grayscale voltage and a low-potential-side grayscale voltage with respect to a reference potential in the two subpixels of the first pixel. In the inversion drive in which are alternately written, a potential difference of the same phase is written, and the two sub-pixels of the second pixel have phases opposite to the phase of the first pixel in the inversion drive. In phase Potential difference is written, is a liquid crystal display device according to claim.

  In the liquid crystal display device of the present invention, the two subpixels of the first pixel and the two subpixels of the second pixel are connected to the source or drain of the pixel transistor of the liquid crystal display panel. They can be arranged on the same straight line parallel to the signal line.

  In the liquid crystal display device of the present invention, the two sub-pixels of the first pixel and the two sub-pixels of the second pixel are connected to a gate of a pixel transistor of the liquid crystal display panel. Are aligned on the same straight line parallel to

  In the liquid crystal display device of the present invention, of the two subpixels, one subpixel includes a first field that is a scanning period in which gradation data corresponding to the first backlight is sequentially written for each line. The gradation data is written only in one of the scanning periods of the second field, which is the scanning period in which the gradation data corresponding to the second backlight is sequentially written for each line. Can do.

  In the liquid crystal display device of the present invention, the area of the color filter of the two subpixels is determined based on a period during which the color emitted from the subpixel is emitted through the color filter. be able to.

  In the liquid crystal display device of the present invention, in the liquid crystal display panel, the first field which is a scanning period in which gradation data corresponding to the first backlight light is sequentially written for each line, and the second backlight light. It can be assumed that the second field, which is a scanning period in which the gradation data corresponding to is sequentially written for each line, overlaps.

  In the liquid crystal display device of the present invention, the backlight divides an irradiation area into a plurality of areas, and irradiates the first backlight light to an area where gradation data corresponding to the first backlight light is written. The irradiation area may be controlled to be scanned so that the area where the gradation data corresponding to the second backlight light is written is irradiated with the second backlight light.

  In the liquid crystal display device of the present invention, the backlight is provided with an extinguishing period in which no backlight is irradiated between the irradiation period of the first backlight light and the irradiation period of the second backlight light. And so on.

  According to the present invention, in a field sequential display device using a color filter together, inversion driving can be performed to obtain a good image display with sufficient image quality.

1 is a diagram schematically showing a liquid crystal display device according to a first embodiment of the present invention. It is a figure which shows the structure of the liquid crystal display panel of FIG. It is a figure which shows the state which displays blue (B) and green (G) in the field sequential system of this embodiment. It is a figure which shows the state which displays blue (B) and red (R) in the field sequential system of this embodiment. It is a table | surface shown about the combination of the color filter and backlight in a liquid crystal display device. It is a figure which shows schematically the control structure of a liquid crystal display device. It is a figure which shows the pixel structure of the liquid crystal display panel which concerns on the liquid crystal display device of 1st Embodiment. 8 is a timing chart showing operation timings of scanning signal lines and data signal lines in the pixel configuration of FIG. 7. It is a figure which shows the structure of the data conversion circuit which concerns on the liquid crystal display device of 1st Embodiment. It is a figure which shows the structure of 1 pixel in the liquid crystal display device of 1st Embodiment. It is a figure which shows the structure of the backlight which concerns on the liquid crystal display device of 1st Embodiment. It is a figure shown about the modification of the backlight which concerns on the liquid crystal display device of 1st Embodiment. It is a figure which shows about operation | movement of a backlight when not scanning a backlight. It is a figure which shows about operation | movement of the backlight at the time of scanning a backlight synchronizing with the scanning of a liquid crystal display panel. It is a figure for demonstrating the scanning of the backlight which concerns on 1st Embodiment. It is a figure which shows the pixel structure of the liquid crystal display panel of the liquid crystal display device which concerns on 2nd Embodiment. FIG. 17 is a timing chart showing operation timings of scanning signal lines and data signal lines in the pixel configuration of FIG. 16. 12 is a timing chart showing timings of operations of scanning signal lines and data signal lines of the liquid crystal display device according to the third embodiment. It is a figure shown about the comparative example of the scanning of a liquid crystal display panel. It is a figure shown about the comparative example of the scanning of a liquid crystal display panel. It is a figure shown about the scanning by the trace drive of a liquid crystal display panel. It is a figure which shows the pixel structure of the liquid crystal display panel of the liquid crystal display device which concerns on 4th Embodiment. FIG. 23 is a timing chart showing operation timings of scanning signal lines and data signal lines in the pixel configuration of FIG. 22. It is a figure which shows the pixel structure of the liquid crystal display panel of the liquid crystal display device which concerns on 5th Embodiment. FIG. 25 is a timing chart showing operation timings of scanning signal lines and data signal lines in the pixel configuration of FIG. 24. FIG. 25 is a timing chart showing a modified example of the operation when trace driving is not applied in the pixel configuration of FIG. 24. It is a figure which shows the pixel structure of the liquid crystal display panel of the liquid crystal display device which concerns on 6th Embodiment. 28 is a timing chart showing operation timings of scanning signal lines and data signal lines in the pixel configuration of FIG. It is a figure which shows the pixel structure of the liquid crystal display panel of the liquid crystal display device which concerns on 7th Embodiment. 30 is a timing chart showing timings of operations of scanning signal lines and data signal lines in the pixel configuration of FIG. 29. FIG. 30 is a timing chart showing a modified example of the operation when the trace drive is not applied in the pixel configuration of FIG. 29. FIG. It is a figure which shows the pixel structure of the liquid crystal display panel of the liquid crystal display device which concerns on 8th Embodiment. FIG. 33 is a timing chart showing operation timings of scanning signal lines and data signal lines in the pixel configuration of FIG. 32. It is a figure which shows the pixel structure of the liquid crystal display panel of the liquid crystal display device which concerns on 9th Embodiment. FIG. 35 is a timing chart showing operation timings of scanning signal lines and data signal lines in the pixel configuration of FIG. 34. FIG. FIG. 35 is a timing chart showing operation timing when trace driving is applied in the pixel configuration of FIG. 34. It is a figure which shows the structure of the backlight of the liquid crystal display device which concerns on 10th Embodiment. It is a figure which shows the backlight lighting method in the backlight of FIG. It is a figure which shows the pixel structure in the liquid crystal display device of a 3 color filter system. It is a figure which shows the pixel structure in the liquid crystal display device of the 2 color filter which applied 1 subpixel inversion alternating current. It is a graph which shows the relationship between the gradation data for AC drive, and a data voltage.

  Before describing the embodiment of the present invention, AC driving of a liquid crystal display panel will be described. 39 and 40 are diagrams illustrating a pixel configuration of a liquid crystal display panel used in the liquid crystal display device. FIG. 39 is a diagram illustrating an example of a pixel configuration in a conventional liquid crystal display device of a three-color filter system of R (red), G (green), and B (blue). FIG. 39 shows an example of a panel in which pixels each having R, G, and B subpixels are arranged in 4 × 3. In the following description, when a subpixel on the liquid crystal display panel is designated, the xth subpixel from the left end along the scanning signal line and the yth subpixel from the upper end along the data signal line are represented as P (x, y). I will do it. At the intersection of the data signal line and the scanning signal line, a TFT connected to each sub-pixel is disposed. In the drawing, D1 to D10 are data signal lines, and G1 to G4 are scanning signal lines.

  In FIG. 39, n is 1 to 4, P (1, n) is an R pixel, P (2, n) is a G pixel, and P (3, n) is a B pixel. Three color sub-pixels are arranged in stripes. The display panel needs to alternately write positive and negative data voltages to sub-pixels in order to prevent burn-in due to bias of applied voltage. Further, at this time, in order to avoid the occurrence of image quality deterioration due to crosstalk of scanning signal lines and data signal lines, it is common to alternately arrange positive and negative sub-pixels spatially. In FIG. 39, the polarities of the sub-pixels at a certain point in time are indicated by + and-signs, P (1,1) and P (3,1) are positive, P (2,1) and P (1 , 2) are arranged in a so-called checkered pattern so that the polarity of each sub-pixel is alternately positive and negative for each sub-pixel in both the data signal line direction and the scanning signal line direction so as to be negative. ing. This is realized not by arranging TFTs only on the left and right sides of the data signal lines but by alternately arranging TFTs on the left and right sides of the data signal lines for each scanning signal line. In this way, power consumption can be reduced while maintaining image quality. Further, this polarity is inverted, for example, every frame. That is, a subpixel having a positive polarity in a certain frame has a negative polarity in the next frame.

  As described above, in FIG. 39, AC is performed in units of one subpixel in the scanning signal line direction and data signal line direction, and in the frame unit in the time direction, and there is no deterioration in image quality such as flicker and crosstalk. Good display can be obtained.

  In AC driving, the polarity of the pixel voltage is switched as follows: frame inversion driving that switches in units of frames, data signal line inversion driving that switches in units of adjacent data signal lines, and scanning signal line inversion driving that switches in units of adjacent scanning signal lines Various AC driving methods such as dot inversion driving that switches in units of sub-pixels have been proposed. When these drive methods are compared, in general, dot inversion drive is the best image quality, data signal line inversion drive and scanning signal line inversion drive have problems such as crosstalk, and frame inversion drive has flicker. .

  On the other hand, the power consumption of the frame inversion driving is the smallest, followed by the data signal line inversion driving, and the power consumption of the scanning signal line inversion driving and the dot inversion driving is larger than these two. However, the above power consumption is the case where TFTs are arranged only on the left and right sides of the data signal lines. If the TFTs are alternately arranged on the left and right sides of the data signal lines as shown in FIG. Dot inversion drive can be realized.

  The data signal lines D1, D2, and D3 in FIG. 39 will be described as an example. When the scanning signal line G1 is selected, the data signal line D2 is connected to the sub-pixel P (2, 1) via the TFT. Similarly, when the scanning signal line G2 is selected, the subpixel P (1,2) is selected, when the scanning signal line G3 is selected, the subpixel P (2,3) is selected, and when the scanning signal line G4 is selected, the subpixel is selected. Connected to P (1,4). The polarities of these subpixels are all negative. Further, all the subpixels connected to the data signal lines D1 and D3 adjacent to the data signal line D2 are positive. That is, the polarity of each data signal line is only the same polarity during one frame period. This corresponds to data signal line inversion driving for the data signal line driving circuit. However, these sub-pixels are alternately arranged on the left and right of the data signal line for each scanning signal line, and as a result, dot inversion driving is realized on the display panel. As described above, by disposing the TFTs alternately on the left and right sides of the data signal line, it is possible to realize the image quality of the dot inversion drive while maintaining the power consumption equivalent to the data signal line inversion drive.

  FIG. 41 is a graph showing an example of the relationship between gradation data and data voltage for AC driving of the display panel. A data voltage corresponding to positive and negative polarities is applied to the data signal line based on the input gradation data. Specifically, when the minimum value of the gradation data that can be displayed on the display panel is Dmin and the maximum value is Dmax, the positive polarity associates the data voltage Vmin with the gradation data Dmin, and the gradation data Dmax. Data voltage + Vmax. On the other hand, in the negative polarity, Dmin and Vmin are associated with Dmax and -Vmax. In other words, the grayscale data Dx satisfying Dmin ≦ Dx ≦ Dmax is associated with the data voltage + Vx in the positive polarity and the data voltage −Vx in the negative polarity. At this time, as shown in the graph of FIG. 41, a relationship of −Vmax ≦ −Vx ≦ Vmin ≦ + Vx ≦ + Vmax is established. The characteristic curve shown in FIG. 41 is appropriately set in advance so that desired display luminance corresponding to the gradation data can be obtained based on the characteristics of the display panel.

  40, the one-subpixel inversion alternating current applied to the display device having the three color filters of FIG. 39 is applied to the display device having the two color filters of B (blue) and Y (yellow) as it is. The case is shown. Note that color display using two color filters will be described in the first embodiment. In FIG. 40, the sub-pixel P (1,1) is a Y pixel, the sub-pixel P (2,1) is a B pixel, and the sub-pixel P (3,1) is also a Y pixel. Sub-pixels are arranged in a stripe pattern. Similarly to FIG. 39, positive and negative subpixels are arranged in a checkered pattern for each subpixel.

  However, considering the case of solid blue display on the entire screen, the B pixels such as the sub-pixel P (2,1) and the sub-pixel P (4,1) are positive and negative corresponding to the blue display data. Polarity voltages are written alternately. For example, as shown in the graph of FIG. 41, if the gradation data is Dmax, the data voltages are + Vmax and -Vmax.

  In this blue monochromatic display, the gradation data of the Y pixel of the sub-pixel P (1, 1) and sub-pixel P (3, 1) is the minimum value Dmin. At this time, since the data voltage is Vmin regardless of whether it is positive or negative, focusing on the scanning signal lines G1 and G2, only the subpixels of the data voltages + Vmax and Vmin are alternately arranged on the scanning signal line G1. On the other hand, in the scanning signal line G2, only the sub-pixels having the data voltages -Vmax and Vmin are alternately arranged. Although the scanning signal lines G1 and G2 both display the same data, the scanning signal line G1 is biased to be positive and the scanning signal line G2 is biased to be negative. That is, alternating current is not normally realized in the scanning signal line direction, and it is perceived as horizontal streak-like image quality degradation. Therefore, it is difficult to apply the conventional one-pixel inversion AC to the two-color filter method in terms of display quality.

  Embodiments of the present invention will be described below with reference to the drawings. In the drawings, the same or equivalent elements are denoted by the same reference numerals, and redundant description is omitted.

[First Embodiment]
FIG. 1 schematically shows a liquid crystal display device 100 according to an embodiment of the present invention. As shown in this figure, the liquid crystal display device 100 includes a liquid crystal display panel 200 fixed to be sandwiched between an upper frame 110 and a lower frame 120, a backlight 360, and the like.

  FIG. 2 shows the configuration of the liquid crystal display panel 200 of FIG. The liquid crystal display panel 200 includes two substrates, a TFT (Thin Film Transistor) substrate 230 and a color filter substrate 220, and a liquid crystal composition is sealed between these substrates. The TFT substrate 230 is provided with scanning signal lines controlled by the scanning signal line driving circuit 330 and data signal lines controlled by the data signal line driving circuit 320, and these signal lines form a sub-pixel 311. ing. Note that the liquid crystal display panel 200 has a number of pixels corresponding to the resolution of the display, but is simplified to avoid complicating the drawing.

  3 and 4 are diagrams for explaining the color display of the liquid crystal display device 100. FIG. The liquid crystal display device 100 is a device that performs color display by a field sequential method, and one pixel 312 of the color filter substrate 220 includes a blue (B) first color filter 222 and a yellow (Y) second color filter 224. With color. The backlight 360 is configured to emit light by switching two colors of the first backlight light 131 and the second backlight light 132 having different colors, and the first backlight light 131 and the second backlight light 132 are mutually transmitted. A selection is made so that a part of the emission spectrum overlaps and the spectrum of the light transmitted through the first color filter 222 also overlaps. In the present embodiment, the first backlight 131 is cyan (C) and the second backlight 132 is magenta (M).

  FIG. 3 is a diagram illustrating a state in which blue (B) and green (G) are displayed. In this state, the backlight 360 emits light in the cyan of the first backlight light 131, and the cyan backlight light becomes blue transmitted light when transmitted through the blue color filter 222 and is transmitted through the yellow color filter 224. It becomes green transmitted light.

  FIG. 4 is a diagram illustrating a state in which blue (B) and red (R) are displayed. In this state, the backlight 360 emits light with magenta of the first backlight light 131. When the magenta backlight light passes through the blue color filter 222, it becomes blue transmitted light, and when it passes through the yellow color filter 224. It becomes red transmitted light.

  Based on the above-described principle, the liquid crystal display device 100 performs display of three primary colors by combining two types of color filters and two types of backlight light, thereby performing full color display.

  The above-described combination of the color of the color filter and the color of the light of the backlight is an example, and the liquid crystal display device of the present invention is not limited to this. For example, the first color filter 222 may be red, the second color filter 224 may be cyan, the first backlight 131 may be magenta, and the second backlight 132 may be yellow. Alternatively, for example, the first color filter 222 may be green, the second color filter 224 may be magenta, the first backlight 131 may be yellow, and the second backlight 132 may be cyan.

  FIG. 5 is a table showing combinations of color filters and backlights in the liquid crystal display device 100. Since the first color filter 222 is configured to include a blue spectral component, the color of the first color filter 222 is blue. On the other hand, since the second color filter 224 is configured to include green and red spectral components, the color of the second color filter 224 is yellow.

  Since the first backlight 131 is configured to mainly include a blue spectral component and a green spectral component, the emission color of the first backlight 131 is cyan. Further, since the second backlight light 132 is configured to mainly include a blue spectral component and a red spectral component, the emission color of the second backlight light 132 is magenta.

  When the first backlight 131 and the first color filter 222 are combined, only the blue spectral component is transmitted. Similarly, when the first backlight 131 and the second color filter 224 are combined, only the green spectral component is transmitted. Similarly, when the second backlight 132 and the first color filter 222 are combined, only the blue spectral component is transmitted. Similarly, when the second backlight 132 and the second color filter 224 are combined, only the red spectral component is transmitted.

  Here, as the light source of the backlight light, for example, a light emitting diode (LED) can be used. For example, a backlight can be configured using three color LEDs as light sources. In this case, for example, the backlight is configured using LEDs of three colors of red, green, and blue. It is preferable that the green and blue LEDs emit light at the same time to make cyan of the first backlight light 131, and the red and blue LEDs emit light at the same time to make magenta of the second backlight light 132. In this case, it is possible to individually control the emission intensities of the red, green, and blue LEDs, and there is a feature that the degree of freedom in adjusting the hue is high.

  Or a backlight can be comprised using LED of two colors as a light source. In this case, for example, it is preferable to use a cyan LED that emits the light of the first backlight 131 and a magenta LED that emits the light of the second backlight 132. Here, as a configuration example of the cyan and magenta LEDs, a material for the LED chip may be selected to obtain a desired emission color. Or you may comprise so that a desired luminescent color may be obtained, for example by combining a blue LED chip and fluorescent substance. For example, when a blue LED chip and a green phosphor are combined, light is emitted from cyan. Further, when a blue LED chip and a red phosphor are combined, magenta light emission is obtained.

  In general, an LED chip has a different temperature-luminance characteristic and life because its constituent material is different for each emission color. In the case of emitting light by combining LED chips of a plurality of colors, for example, the color obtained as the temperature rises changes (color shift). As a display device, since the occurrence of color shift is not preferable, it is necessary to adjust the emission intensity of individual LEDs so as to compensate for the characteristics, and to take control to keep the emission color constant. As the number of LEDs increases, the difficulty level increases. Compared to the method using three-color LEDs, the method using two-color LEDs can more easily configure the backlight and reduce the number of parts. Management costs can be reduced. Furthermore, in the case of a combination of a blue LED and a green or red phosphor, by making the blue LED chip used for both the same type, the temperature characteristics of both can be made uniform, and control is easier. Become.

  In addition to using a blue LED, an LED that combines a near-ultraviolet LED chip and a phosphor can also be used.

  FIG. 6 schematically shows a control configuration of the liquid crystal display device 100. The liquid crystal display device 100 includes a data conversion circuit 350, a timing control circuit 340, a data signal line drive circuit 320, a scanning signal line drive circuit 330, a liquid crystal display panel 200, a backlight drive circuit 370, and a backlight 360. And. The liquid crystal display device 100 has a function of receiving input display data 382 and an input control signal group 381 and driving the liquid crystal display panel 200 and the backlight 360. The input control signal group 381 includes, for example, a vertical synchronization signal that defines one frame period (a period for displaying one screen), a horizontal synchronization signal that defines a horizontal scanning period (a period for displaying one line), and display data It consists of a data valid period signal that defines the valid period, a reference clock signal synchronized with display data, and the like. The input display data 382 and the input control signal group 381 are input to the liquid crystal display device 100 from an external signal generation circuit (not shown).

  The data conversion circuit 350 converts the input display data 382 into converted display data 352 for the liquid crystal display panel 200. The input display data 382 is generally composed of data of three primary colors of R, G, and B. On the other hand, since the liquid crystal display panel 200 is composed of two color filters as described above, the input display data 382 cannot be displayed as it is. Therefore, the data conversion circuit 350 has a function of converting the input display data 382 into converted display data 352 suitable for the liquid crystal display panel 200 and outputting the converted display data 352.

  Further, since the liquid crystal display device 100 uses a field sequential method, a field that is a plurality of writing scan periods is configured and displayed in one frame. For example, if the number of fields is 2, the refresh rate of the display panel is twice the frame frequency of the input display data. At this time, if the frame frequency of the input display data is 60 Hz, the display panel is driven at 120 Hz or higher. Therefore, the data conversion circuit 350 also has a function of converting the frame frequency of the input display data 382. Further, the data conversion circuit 350 generates a conversion control signal group 351 synchronized with the conversion display data 352.

  The conversion control signal group 351 includes a vertical synchronization signal that defines one frame period of the converted display data 352, a horizontal synchronization signal that defines a horizontal scanning period, a display data effective period signal that defines an effective period of the converted display data 352, and a conversion. It is composed of a clock signal synchronized with the display data 352, a field identification signal for identifying the field order, and the like.

  The timing control circuit 340 receives the conversion control signal group 351 and the conversion display data 352 output from the data conversion circuit 350 as inputs. Then, from the conversion control signal group 351 and the conversion display data 352, a data signal line drive circuit control signal group 341 for controlling the data signal line drive circuit 320, output display data 342, and a scanning signal line drive circuit 330 are displayed. This is a circuit for generating a scanning signal line drive circuit control signal group 343 for controlling and a backlight control signal group 344 for controlling the backlight drive circuit 370.

  The scanning signal line drive circuit control signal group 343 includes, for example, a shift signal that defines a scanning signal line selection period for one line, a vertical start signal that defines the start of scanning of the first line, and the like.

  The data signal line driver circuit 320 generates a potential corresponding to the number of display gradations, selects a one-level potential corresponding to the output display data 342, and applies the data voltage 321 to the data signal line D.

  The scanning signal line driving circuit 330 generates a scanning signal line selection signal 331 based on the scanning signal line driving circuit control signal group 343 and outputs it to the scanning signal line G of the liquid crystal display panel 200.

  The sub-pixel 311 of the liquid crystal display panel 200 includes a TFT (Thin Film Transistor) including a source electrode, a gate electrode, and a drain electrode, a liquid crystal layer, and a counter electrode. The TFT is switched by applying a scanning signal to the gate electrode. When the TFT is open, the data voltage is written to the drain electrode connected to one of the liquid crystal layers via the source electrode, and when the TFT is closed, the data voltage is applied to the drain electrode. The written voltage is retained. The drain electrode voltage is Vd, and the counter electrode voltage is Vcom. The liquid crystal layer changes the polarization direction based on the potential difference between the drain electrode voltage Vd and the counter electrode voltage Vcom, and transmits the amount of light transmitted from the backlight 360 disposed on the back surface via the polarizing plates disposed above and below the liquid crystal layer. Changes to perform gradation display.

  The backlight 360 has a function of illuminating the liquid crystal display panel 200. The backlight 360 is configured to be able to illuminate by switching between two types of backlights having different colors. For example, LEDs (light emitting diodes) and CCFLs (cold cathode tubes and HCFLs (hot cathode tubes)) can be used as the light source for the backlight 360. The backlight 360 includes a diffusion sheet, a prism sheet, a brightness enhancement sheet, and the like. The backlight driving circuit 370 is a circuit having a function of driving the backlight 360 based on the backlight control signal group 344, and outputs the backlight driving signal group 371. To do.

  FIG. 7 is a diagram illustrating a pixel configuration of the liquid crystal display panel 200. 7 shows a display panel having a resolution of 4 pixels in the vertical direction and 4 pixels in the horizontal direction (subpixel is 8) for simplification of description, the resolution of the display device to which the present invention is applied is as follows. However, the present invention is not limited to this. A display panel having a larger resolution, for example, a so-called full HD (High Definition) resolution of vertical 1080 pixels and horizontal 1920 pixels (sub-pixel is 3840) may be used. Alternatively, other resolutions may be used.

  In the example shown in FIG. 40, the scanning signal line direction and the data signal line direction are ACed in units of one subpixel (the period is two subpixels). However, in the liquid crystal display device 100, as shown in FIG. The sub-pixel unit (cycle is 4 sub-pixels) in the direction along, and the sub-pixel unit (cycle is 2 sub-pixels) in the direction along the data signal line. By realizing such alternating current, it is possible to suppress the occurrence of horizontal streaks during monochromatic display, which was a problem in the pixel configuration of FIG.

  For example, in the case of displaying a solid blue color on the entire screen, the B pixel P (1,1) has a positive polarity and the B pixel P (3,1) has a negative polarity data voltage. In this manner, the polarity of the connected B pixel in both the scanning signal lines G1 and G2 is alternately positive and negative, and balanced AC driving can be performed without being biased to one of the polarities. Good display quality can be obtained without causing image quality degradation such as streaks.

  Further, in the liquid crystal display device 100, the pixel configuration of the liquid crystal display panel 200 is different from the pixel configuration of FIG. 40 for the purpose of reducing power consumption and suppressing cost increase.

  A common point is that data signal line inversion AC driving is applied by alternately disposing TFTs on the left and right of the data signal line for each scanning signal line, thereby reducing power consumption. That is, for example, in the data signal line D2, transistors connected to the subpixels P (1,2), P (2,2), P (1,4), and P (2,4) are provided. On the other hand, the arrangement of TFTs connected to the scanning signal lines is different.

  In the pixel arrangement of FIG. 40, a TFT is arranged below each scanning signal line. On the other hand, in the pixel arrangement of FIG. 7, TFTs are arranged above and below each scanning signal line, and the upper and lower positions are switched every two sub-pixels. For example, the scanning signal line G2 includes transistors connected to the subpixels P (1,2), P (2,1), P (3,1), P (4,2), P (5,2). It is installed.

  As in the pixel arrangement of FIG. 40, when TFTs are arranged side by side below the scanning signal line, it is not possible to make an alternating current in units of two subpixels. This is due to the following reason.

  The data signal line driving circuit 320 for driving the data signal lines has a first voltage generating circuit that generates a positive data voltage and a second data voltage that generates a negative data voltage for the purpose of reducing the circuit scale. The voltage generation circuit is alternately arranged for each data signal line, and a method is widely adopted in which the voltage generation circuit is connected to the data signal line via a switch that switches between the two based on the polarity signal. In such a data signal line driving circuit, the polarity of the data signal line is inverted in units of one data signal line (period is two data signal lines) such as positive, negative, positive, negative,. On the other hand, in the AC conversion in units of two subpixels shown in FIG. 7, the polarity of the subpixels is inverted in units of two subpixels in the direction along the scanning signal line, such as positive, positive, negative, negative. It is necessary to let Since the data signal line inversion unit of the data signal line driving circuit 320 is different from that of the data signal line driving circuit 320, the data signal line driving circuit 320 cannot be connected as it is, so that it is necessary to newly design a data signal line driving circuit for two sub-pixel alternating current, which increases costs It becomes a factor.

  However, as shown in FIG. 7, if TFTs are provided above and below the scanning signal line and the upper and lower positions are switched in units of two sub-pixels, in order to realize alternating current in units of two sub-pixels, FIG. The data signal line driving circuit used in the pixel arrangement can be applied, and the cost increase can be suppressed.

  With the configuration as described above, high image quality by alternating current in units of two subpixels, low power consumption by data signal line inversion driving, and cost increase by diverting a conventional data signal line driving circuit. The suppression effect can be obtained.

  FIG. 8 is a timing chart showing operation timings of the scanning signal line and the data signal line in the pixel configuration of FIG. The operations of the vertical synchronization signal, the polarity signal, the data signal lines D1 to D5, and the scanning signal lines G1 to G5 are shown. As described above, the vertical synchronization signal is a signal that defines one frame period of the input display data. The polarity signal is one of the data signal line drive circuit control signal group 341 and is a signal that defines the polarity of the display panel. Based on this polarity signal, the data signal line drive circuit 320 determines the polarity for each data signal line.

  In FIG. 8, when the polarity signal is High, odd-numbered data signal lines (D1, D3, etc.) are positive, and even-numbered data signal lines (D2, D4, etc.) are negative. On the contrary, when the polarity signal is Low, the odd-numbered data signal lines have a negative polarity, and the even-numbered data signal lines have a positive polarity. As described above, by controlling the polarity signal, alternating current in the time direction can be performed. In frame inversion driving, the polarity signal is inverted every frame. Similarly, in the data signal line inversion driving, the polarity signal is inverted every frame, and in the scanning signal line inversion driving and the dot inversion driving, the polarity signal is inverted every scanning signal line selection period. The smaller the inversion frequency of the polarity signal is, the less charge / discharge of the pixel is, so the power consumption becomes smaller. At this time, from the viewpoint of preventing flicker and reducing power consumption, it is preferable that the first field and the second field have the same polarity.

  In one frame period (time t1 to t11) defined by the vertical synchronization signal, a first field (time t1 to t6) that is a scanning period in which gradation data corresponding to the first backlight 131 is written, and a second There is a second field (time t6 to t11) that is a scanning period in which gradation data corresponding to the backlight 132 is written. In the timing chart of FIG. 8, in the first field period, data B is written in the B pixel, data YG is written in the Y pixel, the backlight is lit in C (cyan), and blue and green are displayed. In the second field period, data B is written to the B pixel, data YR is written to the Y pixel, the backlight is lighted at M (magenta), and blue and red are displayed.

  In the data writing, the display on the display panel is updated (refreshed) at least once in each of the first field period and the second field period. Specifically, in each field period, each of the scanning signal lines G1 to G5 is sequentially selected at least once, and data for each sub-pixel connected to each scanning signal line is displayed in the scanning signal line selection period. Data voltages are supplied (written) from the signal lines D1 to D9. For example, the scanning signal line G1 is selected at times t1 to t2, the scanning signal line G2 is selected at times t2 to t3, and thereafter, the same operation is repeated for each scanning signal line. At the same time, the data voltage of the corresponding subpixel is supplied to each data signal line at each time. In FIG. 8, the types of data voltages supplied from the data signal lines are distinguished by hatching and hatching.

  In the data signal lines of FIG. 7, there are data signal lines in which TFTs are not arranged at intersections with the scanning signal lines on the four sides of the display panel. When the scanning signal line is selected, a dummy data voltage not used for display is supplied to the data signal line in which the TFT is not arranged. Alternatively, dummy subpixels that are not used for display are prepared on the outer periphery of the upper, lower, left, and right sides, and dummy subpixels are connected to data signal lines not provided with TFTs, and a dummy data voltage is supplied. It can be. For example, at time t1 to t2, the scanning signal line G1 is selected, and at the same time, the sub-pixel P (1,1) is selected for the data signal line D1, the sub-pixel P (4,1) is the data signal for the data signal line D4. The data voltage of the sub-pixel P (5, 1) is supplied to the line D5, and the data voltage of the sub-pixel P (8, 1) is supplied to the data signal line D8. On the other hand, dummy data voltages are supplied to the data signal lines D2, D3, D6 and D7.

  As described above, in the liquid crystal display device 100, by adopting the pixel configuration described with reference to FIG. 7, image quality degradation such as a horizontal stripe at the time of monochromatic solid display, which is one of the problems in the configuration of FIG. 40, is generated. Therefore, the data signal line inversion drive can be realized, and both low power consumption and high image quality can be achieved.

  FIG. 9 is a diagram showing a configuration of the data conversion circuit 350. The data conversion circuit 350 converts the input display data 382 into converted display data 352 for the liquid crystal display panel 200. The data conversion circuit 350 includes an n-times speed conversion circuit 710, a frame memory 720, a field counter 730, a line counter 740, a dot counter 750, a line memory 760, a selector 770, and an arithmetic circuit 780.

  The n-times speed conversion circuit 710 generates and outputs n-times speed display data 712 obtained by multiplying the frame frequency of the input display data 382 by n (n is a natural number of 2 or more) in order to generate field data. Here, for example, n = 2. The n-times speed of data can be realized, for example, by reading the input display data 382 written once in the frame memory 720 n times during one frame period. Further, the n × speed conversion circuit 710 generates a conversion control signal group 351.

  The field counter 730 is a counter circuit that generates a field counter value 731 for identifying the field of the n-times speed display data 712 from the conversion control signal group 351. The line counter 740 is a counter circuit that generates a line counter value 741 for identifying the vertical position of the n-times speed display data 712, that is, the line position, from the conversion control signal group 351. The dot counter 750 is a counter circuit that generates a dot counter value 751 for identifying the horizontal position of the n-times speed display data 712, that is, the position of a dot (pixel), from the conversion control signal group 351.

  The line memory 760 is a line memory that can store n-times display data for at least one line, and holds line delay n-times display data 761 obtained by delaying n-times display data in units of lines. It is used to refer to the value of the line delay n-times display data 761, for example, the value of the n-times display data 712 one line before.

  The selector 770 uses the field counter value 731, the line counter value 741, and the dot counter value 751 to select pixel data to be displayed from the n × speed display data 712 and the line delay n × speed display data 761, and Output as replacement display data 771. Here, selection of pixel data corresponds to rearrangement of pixel data. Here, when selecting data, that is, rearranging data, the decoder circuit of the selector is configured so that appropriate pixel data is output based on the pixel configuration of the display panel.

  The arithmetic circuit 780 performs color conversion processing on the rearranged display data 771 to generate and output converted display data 352.

  The color conversion processing includes, for example, γ conversion for converting the RGB data of the rearranged display data 771 into the respective luminance values, and the luminance values to be output by the respective pixels by calculating the respective luminance values of RGB according to the display panel. Can be configured by conversion processing such as matrix conversion for recalculating, and inverse γ conversion for returning the matrix-converted luminance value to the converted display data 352 along the γ characteristics of the display panel.

  FIG. 10 is a diagram illustrating a configuration of one pixel in the liquid crystal display device 100. In the liquid crystal display device 100, one pixel is composed of two subpixels. One subpixel is a first subpixel 810 having a first color filter. The other sub-pixel is a second sub-pixel 820 having a second color filter. At this time, if the area of the first subpixel 810 and the second subpixel 820 is p: q, it can be configured such that p: q ≠ 1: 1. More specifically, the liquid crystal display device 100 is preferably configured so that p: q = 1: 2.

  As shown in FIG. 10, the first subpixel 810 is described as B, and the second subpixel 820 is described as Y. The second subpixel 820 generates different colors in the first field and the second field. Since the first backlight 131 is C (cyan), G is colored in the first field, and since the second backlight 132 is M (magenta), R is colored in the second field. On the other hand, the first subpixel 810 colors B in both the first field and the second field. This indicates that the light emission period is different for each color of RGB.

  If the periods of the first field and the second field are u and v, respectively, the ratio of the light emission period is R: G: B = u: v: u + v. For example, if u: v = 1: 1, then R: G: B = 1: 1: 2, and the R and G emission periods are ½ of the B emission period. This simply indicates that the emission intensity of R and G is ½ of the emission intensity of B. However, this is not preferable for adjusting the color temperature by balancing the emission colors of the display device.

  On the other hand, this problem can be solved by changing the areas of the first subpixel 810 and the second subpixel 820. The emission intensity of each pixel is the product of the area of the subpixel and the emission time. Specifically, R: G: B = u × q: v × q: (u + v) × p. At this time, as described above, if u: v = 1: 1 and p: q = 1: 2, R: G: B = 1 × 2: 1 × 2: (1 + 1) × 1 = 2: 2: 2, and the emission intensity of each color of R, G, B can be made uniform and balanced.

  Note that the area ratio of the sub-pixels of the present invention is not limited to this area ratio. Depending on the spectral distribution of the two types of color filters and the spectral distribution of the two types of backlight light, it may be easier to adjust the color temperature or the intensity of transmitted luminance may be higher than this area ratio. . In such a case, it is preferable to positively change u, v, p, and q other than the above values so that desired characteristics can be obtained.

  For example, it may be configured to be approximately p: q = 1: 1, or may be configured with other ratios. Further, the ratio u: v of the lengths of the first field and the second field is not necessarily limited to 1: 1. Further, when displaying input display data of a specific pattern, for example, when displaying an achromatic monochrome image such as white or gray over the entire surface of the display panel, one frame period is not divided into two fields. Two types of backlight light may be emitted at the same time. In this case, since the light emission time of both the first backlight light 131 and the second backlight light 132 is doubled, the light emission intensity is increased. Thereby, for example, it is possible to improve the maximum luminance at the time of full white display.

  Alternatively, for example, when displaying input display data that does not include any display of red or green, the entire frame period is handled as the first or second field, and the other field is not provided. You can also. For example, when displaying a full-surface green solid image, it is not necessary to display red, so the second field is unnecessary. Therefore, the entire one frame period can be handled as the first field. In this case, since the period of the first field is extended, the intensity of the first backlight 131 is increased. As a result, it is possible to obtain the effect that the luminance of the image is improved and the color development becomes bright.

  FIG. 11 is a diagram illustrating a configuration of the backlight 360. The backlight 360 is a so-called direct-type backlight in which light sources are arranged directly below the display panel, and an LED (light emitting diode) is used as the light source. The backlight 360 is configured by arranging LEDs in a grid on a frame 2100.

  At this time, two types of LEDs, that is, the LED 2101 that outputs the first backlight light 131 and the LED 2102 that outputs the second backlight light 132 are mixed and arranged. At this time, it is preferable to arrange the two types of LEDs in a staggered manner in order to eliminate the occurrence of uneven brightness and color. Or LED which can light-emit two backlight lights, the 1st backlight light 131 and the 2nd backlight light 132 with one package, can also be used. In this case, since it is not necessary to mix and arrange two types of packages, they can be simply arranged in a lattice pattern.

  FIG. 11 shows an example in which the interval xa between the LEDs adjacent in the left-right direction and the interval ya between the LEDs adjacent in the up-down direction are substantially equal. However, as shown in FIG. The interval xb may be different from the interval yb between the vertically adjacent LEDs. At this time, it is preferable to adjust xb and yb so that LEDs of the same color are arranged at the vertices of a regular triangle.

  Further, it is preferable that the backlight 360 is configured to be controlled to be turned on / off by being divided into a plurality of regions in the vertical direction. FIG. 11 shows a case where the backlight is divided into four areas 2110, 2120, 2130, and 2140. Further, it is preferable that a so-called scanning is possible in which a plurality of areas are sequentially turned on in synchronization with the scanning of the liquid crystal display panel 200. The reason for this will be described with reference to FIG.

  FIG. 13 and FIG. 14 are diagrams showing a comparative example of scanning of the liquid crystal display panel 200 and scanning of the backlight 360. Here, FIG. 13 is a comparative example when the backlight is not divided and the backlight is not scanned. The horizontal axis represents time, and the vertical axis represents the scanning position of the display panel and the lighting timing of the backlight. A vertical synchronization signal is also shown.

  The first field data is written on the display panel with the time t1 to t5 as the first field, and the first backlight 131 is illuminated. Further, the second field is written on the display panel with the time t5 to t9 as the second field, and the second backlight 132 is illuminated. In the figure, the lighting period of the first backlight light 131 and the lighting period of the second backlight light 132 are indicated by the presence or absence of shading.

  At this time, in the uppermost stage of the screen, the liquid crystal display panel 200 and the backlight light correspond appropriately, so that color display can be performed normally. However, since it takes time to scan the display panel, for example, at the uppermost stage of the screen, the correspondence between the display panel and the backlight becomes impossible. For example, from time t5 to t9, the display panel displays the first field data, while the backlight is illuminated with the second backlight 132. For this reason, normal color display cannot be performed. This is because the light emission is switched at the same time in the backlight.

  FIG. 14 is a comparative example when the backlight 360 is scanned in synchronization with the scanning of the liquid crystal display panel. Here, as described with reference to FIGS. 11 and 12, the backlight is divided into four in the vertical direction. In this case, the uppermost region of the backlight is illuminated with the first backlight 131 at times t1 to t5 and illuminated with the second backlight 132 at times t5 to t9. On the other hand, in the second region from the top, the first backlight 131 emits light at times t2 to t6, and the second backlight 132 is illuminated at times t6 to t10. Thereafter, similarly, the light emission timing is shifted for each region. With such a configuration, the scanning of the liquid crystal display panel and the backlight can be associated with each other even in the lower stage of the screen, so that relatively normal color display can be performed.

  However, even if the backlight is scanned as shown in FIG. 14, color unevenness occurs at the boundary of the backlight region. The number of divisions of the backlight area is smaller than the number of sub-pixels in the vertical direction of the display panel. For example, when the resolution of the display panel is full HD, the number of subpixels (number of rows) in the vertical direction is 1080, but it is not realistic to divide the backlight into 1080 areas. Therefore, one backlight region illuminates a plurality of rows of subpixels. For example, in a full HD resolution liquid crystal display device, when the backlight region is divided into four, one backlight region includes 270 rows. At this time, the scanning time of the liquid crystal display panel is also different between the uppermost stage and the lowermost stage of the backlight region. This causes color unevenness at the backlight region boundary.

  For example, the situation at the time t1 of the backlight area in the uppermost stage of the backlight will be described. At this time, in the upper part of the backlight region, the first field data is displayed on the liquid crystal display panel and illuminated with the first backlight 131, so that normal color display can be performed. On the other hand, in the lower part of the backlight area, since the liquid crystal display panel has not been scanned yet, the data in the second field of the previous frame remains displayed. However, since the area is illuminated with the first backlight 131, an erroneous color display is performed. This phenomenon will be eliminated at time t2, but erroneous color display will be performed even for a short time, so that color unevenness appears on the screen.

  FIG. 15 is a diagram for explaining backlight scanning applied to the backlight 360 of the liquid crystal display device 100 according to the first embodiment of the present invention. When switching between the first backlight 131 and the second backlight 132 in each area of the backlight 360, both the backlights are turned off once. Further, the turn-off operation is linked with the scanning of the liquid crystal display panel 200. Specifically, before the scanning of the display area of the liquid crystal display panel 200 illuminated by the backlight area is started, both the first backlight light 131 and the second backlight light 132 are turned off to scan the display area. After ending, either one of the backlights is turned on again. By performing the backlight scanning as shown in FIG. 15, it is possible to avoid the occurrence of color unevenness at the region boundary. Furthermore, since the backlight is turned off, the so-called moving image blur of the display device can be reduced.

  Note that FIG. 15 shows an example of a liquid crystal display device that does not perform trace driving, which will be described later, but the present backlight can be similarly applied to a liquid crystal display device that performs trace driving.

[Second Embodiment]
FIG. 16 is a diagram showing a pixel configuration of the liquid crystal display panel 411 of the liquid crystal display device according to the second embodiment of the present invention. FIG. 17 is a timing chart showing operation timings of the scanning signal lines and the data signal lines in the pixel configuration of FIG. The first embodiment is different from the first embodiment only in the configuration and operation timing chart of the liquid crystal display panel, and the other configurations are the same, and thus the description of the other configurations is omitted.

  In the first embodiment, two types of sub-pixels B and Y are alternately connected to one scanning signal line. In this embodiment, one type of B or Y is used for one scanning signal line. Only the sub-pixels are connected. Further, the scanning signal lines connected only to the B pixels and the scanning signal lines connected only to the Y pixels are alternately arranged. Specifically, the sub-pixels P (2,1), P (2,2), P (4,1), P (4,2), etc. are connected to the scanning signal line G2. On the other hand, sub-pixels P (1,2), P (1,3), P (3,2), P (3,3), etc. are connected to the scanning signal line G3. As a result, either the B pixel or the Y pixel can be selectively updated.

[Third Embodiment]
FIG. 18 is a timing chart showing operation timings of the scanning signal lines and the data signal lines of the liquid crystal display device according to the third embodiment of the present invention. In the present embodiment, the same liquid crystal display panel 411 as that in the second embodiment is used. Note that the second embodiment is different from the second embodiment only in the operation timing chart, and the other configurations are the same, so the description of the other configurations is omitted.

  Since the Y pixel has different colors to be displayed in the first field and the second field, it is necessary to update data for each field. On the other hand, since the B pixel displays blue in both the first field and the second field, it is not necessary to update data for each field. In other words, data may be updated in one of the first field and the second field.

  For example, as shown in FIG. 18, in the first field, all scanning signal lines are selected, and the data of both the B pixel and the Y pixel are updated. However, in the second field, only the Y pixel is updated by selecting only the scanning signal lines G1, G3, and G5 to which the Y pixel is connected. The scanning signal lines G2 and G4 to which the B pixel is connected are not selected. Further, in FIG. 17 of the second embodiment, during the period when the scanning signal lines G2 and G4 are selected, the data voltage is not supplied to each data signal line, or a dummy voltage is supplied.

  With such a configuration, the number of times of data voltage supply of the data signal line in the second field or the frequency of data voltage change is reduced. Thereby, the power consumption of the data signal line driving circuit can be reduced.

[Fourth Embodiment]
In the third embodiment, in the second field, a non-selection period in which the scanning signal line of the B pixel is not selected is provided. However, providing this non-selection period can be considered useless. If the time devoted to the non-selection period can be used to extend the selection period (writing time) of other scanning signal lines, insufficient writing of the data voltage is less likely to occur, which is advantageous for driving a high refresh rate. It is. However, it is not possible to simply reduce the dead time.

  19-21 is a figure for demonstrating the solution method of the above-mentioned subject. FIG. 19 is a diagram in which the timing chart of FIG. 8 and the like is rewritten to show the entire screen. The horizontal axis represents time, and the vertical axis represents the scanning position of the liquid crystal display panel. A vertical synchronization signal is also shown. As shown in FIG. 19, if one frame period is time t1 to t9, the first field is time t1 to t5, and each scanning signal line is selected from the uppermost stage to the lowermost stage of the screen to select the data voltage. Is written (scanned). This scan is shown at 1101. The second field is scanned from time t5 to t9 in the same manner. This scan is shown at 1102.

  On the other hand, FIG. 20 shows an example of scanning when the non-selection period of the second field described with reference to FIG. 18 is eliminated. The non-selection period in FIG. 18 occurs at a rate of one for two scanning signal lines. If this non-selection period is eliminated, scanning of one screen can be executed at twice the speed. For example, as shown in FIG. 20, when scanning of the second field is started at time t5, scanning of one screen is completed at time t7. This scan is shown at 1104. The first field scan is the same as in the example of FIG. This scan is shown at 1103. In this case, brightness and color gradients occur at the top and bottom of the display screen. For example, the period in which the data of the first field is held has the length of time t1 to t5 at the top of the screen, but only the length of time t5 to t7 at the bottom of the screen. Similarly, the period in which the data of the second field is held is t5 to t9 at the top of the screen, and t7 to t13 at the bottom. In other words, the period in which data is held is not uniform between the upper and lower portions of the screen, which causes the occurrence of luminance and color gradients.

  FIG. 21 shows a method for solving this problem. As described above, the problem of luminance gradient and color gradient when the non-selection period is eliminated is unavoidable as long as the first field and the second field are implemented separately. However, this problem can be solved by alternately scanning the first field and the second field.

  The first field is implemented from time t1 to time t9. This scan is shown at 1105. On the other hand, the second field is implemented from time t5 to time t13. This scan is shown at 1106. Here, the first field and the second field overlap from time t5 to t9. At this time, both scanning is not performed at the same time, but both are performed alternately.

  Here, in the first field and the second field, by appropriately setting the length of the scanning signal line selection period, the data holding period can be made uniform between the upper part and the lower part of the screen. Here, since the first field is driven so that the second field follows, this method is called trace driving. Hereinafter, the trace driving will be described in more detail with reference to FIGS.

  FIG. 22 is a diagram showing a pixel configuration of the liquid crystal display panel 412 of the liquid crystal display device according to the fourth embodiment of the present invention. FIG. 23 is a timing chart showing operation timings of the scanning signal lines and the data signal lines in the pixel configuration of FIG. The first embodiment is different from the first embodiment only in the configuration and operation timing chart of the liquid crystal display panel, and the other configurations are the same, and thus the description of the other configurations is omitted.

  In the third embodiment, after the scanning for one screen in the first field is completed, the scanning for one screen in the second field is performed. That is, the first field and the second field are independent. On the other hand, the fourth embodiment is different in that the first field and the second field overlap as shown in FIG.

  During the period from time t1 to time t3, the scanning signal lines G1 and G2 are selected, and the first field data is written. Subsequently, the scanning signal line G5 is selected at time t3 to t4, and the data of the second field is written. Similarly, the data of the first field is written at times t4 to t6 and t7 to t8, and the data of the second field is written at times t6 to t7, t9 to t10, and t12 to t13.

  As described above, by alternately writing the data voltages of the first field and the second field and further appropriately adjusting the writing time, the scanning speed of the first field is equal to the scanning speed of the second field. Can be controlled. Thereby, the inclination of a brightness | luminance and a color can be suppressed at the upper and lower sides of a screen.

  In the configurations of the second and third embodiments, the length of the selection period is set so that all the scanning signal lines are selected twice in one frame period T. In these embodiments, since there are five scanning signal lines, the selection period per scanning signal line is 1/10 × T. On the other hand, in this embodiment, it is not necessary to select two scanning signal lines to which the B pixel is connected among the five scanning signal lines, and eight scanning signal lines (= 5) in one frame period. × 2-2) What should be selected? Therefore, the selection period per scanning signal line may be extended to 1/8 × T.

  In the present embodiment, a non-selection period is provided between times t8 and t9 after the lowermost scanning signal line G5 is selected. This is a measure for keeping the scanning signal line scanning interval in the second field constant. In the first field, two pairs other than the lowest scanning signal line are selected. However, since the number of scanning signal lines is an odd number, only the lowest stage is spaced by one scanning period and is balanced with other scanning signal lines.

  In the configurations of the second and third embodiments, in the case of a display device in which the vertical resolution (= the number of subpixels) is N (N is a natural number), the total number of scanning signal lines is N + 1, and the scanning signal lines The selection period per one is 1 / (2 × N + 2) × T. On the other hand, in the fourth embodiment, the number of scanning signal lines connecting Y pixels is N / 2 + 1, and the number of scanning signal lines connecting B pixels is N / 2, so scanning should be performed in one frame period. The number of scanning signal lines is 3/2 × N + 2 (= (N / 2 + 1 + N / 2) × 2-N / 2), and the selection period per scanning signal line is 1 / (3/2 × N + 2). ) Can be extended to xT. Since N = 1080 in the so-called full HD resolution, in the fourth example, the selection period per scanning signal line is extended to approximately 1.3 times compared to the second and third embodiments. be able to. In other words, the data writing time can be afforded, which is advantageous for increasing the refresh rate. As described above, a display device that supports trace driving has an advantage that a writing time can be increased and a high refresh rate can be easily achieved as compared with a display device that does not.

  It is necessary to prevent the polarity of each pixel from changing in the first field and the second field that are started in the same frame. In the present embodiment, as shown in FIG. 23, the times t1 to t3, t4 to t10, and t12 to t13 are fields that start in the same frame, so the polarity signals are the same. On the other hand, the time t3 to t4 is a field that starts in the previous frame, and the time t10 to t12 is the next frame, so the polarities are different.

[Fifth Embodiment]
FIG. 24 is a diagram showing a pixel configuration of the liquid crystal display panel 413 of the liquid crystal display device according to the fifth embodiment of the present invention. The first embodiment is different from the first embodiment only in the configuration and operation timing chart of the liquid crystal display panel, and the other configurations are the same, and thus the description of the other configurations is omitted.

  In this embodiment, two rows of subpixels are defined as one unit, and three scanning signal lines are wired per unit. Scanning signal lines are arranged above, in the center, and below the subpixels in the two rows. The upper scanning signal line is connected to the upper Y pixel of the two rows of subpixels, the central scanning signal line is connected to the B pixel of the two rows of subpixels, and the lower scanning signal line is The lower Y pixels in the two rows of sub-pixels are connected. Specifically, the Y pixel in the first row is connected to the scanning signal line G1. The B pixels in the first and second rows are connected to the scanning signal line G2. The Y pixels on the two rows are connected to the scanning signal line G3.

  In addition, two subpixels adjacent to each other in the upper and lower portions in one unit are respectively connected to left and right data signal lines sandwiching the subpixel. At this time, when one is connected to the left data signal line, the other is connected to the right data signal line. Further, when one of the sub-pixels of the same color adjacent to each other with one row of sub-pixels of another color is connected to the left data signal line, the other is connected to the right data signal line. Specifically, the subpixel P (1,1) is on the scanning signal line G1 and the data signal line D1, the subpixel P (1,2) is on the scanning signal line G3 and the data signal line D2, and the subpixel P (3 , 1) is connected to the scanning signal line G1 and the data signal line D4, and the sub-pixel P (3, 2) is connected to the scanning signal line G3 and the data signal line D3. Similarly, the sub-pixel P (2,1) is on the scanning signal line G2 and the data signal line D2, and the sub-pixel P (2,2) is on the scanning signal line G2 and the data signal line D3, and the sub-pixel P (4,1 ) Is connected to the scanning signal line G2 and the data signal line D4, and the sub-pixel P (4, 2) is connected to the scanning signal line G2 and the data signal line D5. With the above configuration, the data signal line driver circuit 320 can be applied.

  FIG. 25 is a timing chart showing operation timings of the scanning signal lines and the data signal lines in the pixel configuration of FIG. When writing Y pixels, it differs from the other embodiments described so far in that the upper and lower scanning signal lines are selected simultaneously. For example, the scanning signal lines G1 and G3, and G4 and G6 are selected simultaneously.

  As in the fourth embodiment, it is possible to implement a drive that updates the Y pixel for each field and updates the B pixel once in two fields by trace driving. Furthermore, in the case of the present embodiment, if the vertical resolution N is an even number, the number of scanning signal lines for driving the Y pixels is also an even number. There is an advantage that a non-scanning period after the scanning signal line is selected becomes unnecessary. Also in this configuration, when N is sufficiently large, for example, in a display device with full HD resolution, the length of the scanning signal line selection period can be about 1.3 times that in the case of no trace driving.

  FIG. 26 is a timing chart showing a modified example of the operation when the trace driving is not applied in the fifth embodiment. Both Y and B pixels are updated twice per frame. As described above, the display device according to the fifth embodiment can be used by switching between application / non-application of trace driving.

[Sixth Embodiment]
FIG. 27 is a diagram showing a pixel configuration of the liquid crystal display panel 414 of the liquid crystal display device according to the sixth embodiment of the present invention. FIG. 28 is a timing chart showing operation timings of the scanning signal lines and the data signal lines in the pixel configuration of FIG. The first embodiment is different from the first embodiment only in the configuration and operation timing chart of the liquid crystal display panel, and the other configurations are the same, and thus the description of the other configurations is omitted.

  In the embodiments described so far, one data signal line is provided between the left and right adjacent subpixels. In the sixth embodiment, as shown in FIG. In addition, two data signal lines are provided. The TFTs are arranged at different positions for each scanning line. Specifically, the odd-numbered scanning signal lines have 4 subpixels as a unit, and the TFTs are arranged in the order of left, left, right, and right, and the even-numbered scanning signal lines have 4 subpixels in the same manner. One unit is set, and the TFTs are arranged in the order of right, right, left, and left.

  With the above configuration, the data signal line driver circuit 320 can be applied. In the present embodiment, data can be simultaneously written in two rows of subpixels adjacent vertically. Thereby, compared with 1st Embodiment, the frequency | count of writing can be made into about 1/2. In other words, the data writing time can be approximately doubled, and high refresh rate driving can be performed.

[Seventh Embodiment]
FIG. 29 is a diagram showing a pixel configuration of the liquid crystal display panel 415 of the liquid crystal display device according to the seventh embodiment of the present invention. The first embodiment is different from the first embodiment only in the configuration and operation timing chart of the liquid crystal display panel, and the other configurations are the same, and thus the description of the other configurations is omitted.

  This embodiment is different from the other embodiments in that one scanning signal line is arranged above and below each row. Only one of the Y pixel and the B pixel is connected to each scanning signal line, and TFTs are alternately arranged on the left and right in the subpixels of the same color that are adjacent to the left and right across the other subpixel. The TFTs are arranged at different positions on the left and right even in the subpixels of the same color that are adjacent vertically. Specifically, for example, the subpixel P (1,1) is on the scanning signal line G1 and the data signal line D1, and the subpixel P (1,2) is on the scanning signal line G3 and the data signal line D2, and the subpixel P is on. (3, 1) is connected to the scanning signal line G1 and the data signal line D4, and the sub-pixel P (3, 2) is connected to the scanning signal line G3 and the data signal line D3. Similarly, the sub-pixel P (2,1) is on the scanning signal line G2 and the data signal line D3, and the sub-pixel P (2,2) is on the scanning signal line G4 and the data signal line D2, and the sub-pixel P (4,1 ) Is connected to the scanning signal line G2 and the data signal line D4, and the sub-pixel P (4, 2) is connected to the scanning signal line G3 and the data signal line D5.

  FIG. 30 is a timing chart showing operation timings of the scanning signal lines and the data signal lines in the pixel configuration of FIG. In this embodiment, when writing data to the Y pixel, two odd-numbered scanning signal lines are selected. When writing data to the B pixel, two even-numbered scanning signal lines are selected. Specifically, at time t1 to t2, the scanning signal lines G1 and G3 are selected and YG data of the first field is written. At time t2 to t3, scanning signal lines G2 and G4 are selected and B data in the first field is written. Thereafter, repeat until the bottom of the screen.

  In addition, from time t4 to t5, the scanning signal lines G1 and G3 are selected and YR data of the second field is written. Thereafter, repeat until the bottom of the screen. By performing such driving, trace driving can be realized.

  FIG. 31 is a timing chart showing a modification in the case where the trace driving is not performed in the seventh embodiment. In this modification, the trace driving is not performed, and both the Y pixel and the B pixel are updated in both the first and second fields.

[Eighth Embodiment]
FIG. 32 is a diagram showing a pixel configuration of the liquid crystal display panel 416 of the liquid crystal display device according to the eighth embodiment of the present invention. FIG. 33 is a timing chart showing operation timings of the scanning signal lines and the data signal lines in the pixel configuration of FIG. The first embodiment is different from the first embodiment only in the configuration and operation timing chart of the liquid crystal display panel, and the other configurations are the same, and thus the description of the other configurations is omitted.

  As shown in FIG. 32, it differs from the previous embodiments in that two rows of subpixels are used as one unit and one scanning signal line is wired in the center of the two rows. Upper and lower subpixels are connected to the scanning signal line. On the other hand, it is the same as the sixth embodiment shown in FIG. 27 in that two data signal lines are provided between the left and right adjacent subpixels. The sub-pixels connected to the scanning signal line are arranged in the order of left, right, left, and right with 4 sub-pixels as one unit, and the subsequent 4 pixels are inverted in position to the right, left, right, left Arrange in order, and thereafter repeat in units of 4 sub-pixels.

  With the above configuration, the data signal line driver circuit 320 can be applied. In the present embodiment, data can be simultaneously written in two rows of subpixels adjacent vertically. For example, compared with the first embodiment, the number of times of writing can be reduced to about ½. In other words, the data writing time can be approximately doubled, and high refresh rate driving can be performed.

[Ninth Embodiment]
FIG. 34 is a diagram showing a pixel configuration of the liquid crystal display panel 417 of the liquid crystal display device according to the ninth embodiment of the present invention. The first embodiment is different from the first embodiment only in the configuration and operation timing chart of the liquid crystal display panel, and the other configurations are the same, and thus the description of the other configurations is omitted.

  In the first to eighth embodiments described above, the sub-pixels of two colors are arranged in a stripe shape in the vertical direction. On the other hand, in the ninth embodiment, the sub-pixels of two colors are arranged in a stripe shape in the horizontal direction. Accompanying this change in arrangement, the alternating current is also changed in units of two subpixels.

  In the present embodiment, it is common that AC is converted in units of 2 sub-pixels, but the pattern is rotated 90 degrees as compared with the above-described embodiment. Specifically, in the first to eighth embodiments, in the liquid crystal display device according to the first embodiment of the present invention, the sub-pixel unit (period is 4 sub-pixels) in the direction along the scanning signal line direction. Pixel) and in the direction along the data signal line, alternating current is made in units of one subpixel (cycle is two subpixels). On the other hand, in the ninth embodiment, one subpixel unit (period is two subpixels) in the direction along the scanning signal line direction, and two subpixel units (period is four subpixels) in the direction along the data signal line. Pixel).

  However, it is common that the TFTs of the liquid crystal display panel are arranged on the left and right sides of the data signal lines to realize alternating current in units of two subpixels by data signal line inversion driving.

  35 and 36 are timing charts showing timings of operations of the scanning signal lines and the data signal lines in the pixel configuration of FIG. The timing chart of FIG. 35 is a timing chart when the trace driving is not performed, and the timing chart of FIG. 36 is a timing chart when the trace driving is performed.

[Tenth embodiment]
FIG. 37 is a diagram showing a configuration of the backlight 510 of the liquid crystal display device according to the tenth embodiment of the present invention. Since only the configuration of the backlight is different from that of the first embodiment, and the other configurations are the same, the description of the other configurations is omitted.

  The backlight 510 is a so-called side light or edge light type backlight in which a light source is disposed on the side surface of the liquid crystal display panel 200 and light emitted from the light source is guided by the light guide plate 2410 to illuminate the entire liquid crystal display panel 200. is there. As the light source, LEDs (light emitting diodes) arranged in a straight line on the substrate 2420 are used.

  In the present embodiment, the case where the substrate 2420 is arranged on one side of the light guide plate 2410 is shown, but a configuration may be adopted in which the substrate 2420 is arranged on two sides, three sides, and four sides.

  Similar to the backlight 360 of the first embodiment, two types of LEDs, the LED 2421 that outputs the first backlight light 131 and the LED 2422 that outputs the second backlight light 132, are mixed and arranged. At this time, it is preferable to arrange the two types of LEDs in a staggered manner in order to eliminate the occurrence of uneven brightness and color.

  Or LED which can light-emit two backlight light of the 1st backlight light 131 and the 2nd backlight light 132 with one package can also be used. In this case, there is an advantage that it is not necessary to mix and arrange two types of packages.

  Here, in the edge light type backlight as shown in FIG. 37, unlike the direct type backlight 360 shown in the first embodiment, the backlight is divided into a plurality of regions and individually illuminated. Have difficulty. This is because even if the light sources on the substrate 2420 are individually made to emit light, only a part of the area cannot be selectively illuminated because the light guide plate illuminates a wide range. That is, in the edge light type backlight, since the backlight cannot be scanned as applied in the first embodiment, the problem regarding the color display described in the column of the first embodiment occurs.

  FIG. 38 is a diagram illustrating a backlight lighting method in the backlight 510 of the present embodiment. As described with reference to FIGS. 13 and 14, the above-described problem is caused by lighting the backlight while the field data displayed on the display panel is switched. As shown in FIG. 4, the backlight is turned off during the period of scanning the display panel.

  At this time, as described with reference to FIG. 13, if all the time of the first field and the second field is used for scanning, the backlight cannot be turned on. Therefore, in order to secure a period for turning on the backlight, it is necessary to scan the liquid crystal display panel in a shorter period. For example, at times t1 to t3, the backlight is turned off and used for the first field of the display panel. Subsequently, the backlight is turned on with the first backlight 131 after time t3 when the scanning of the display panel is completed. Similarly, at times t5 to t7, the backlight is turned off and used for the second field of the liquid crystal display panel. Subsequently, the backlight is turned on with the second backlight 132 after time t5 when the scanning of the display panel is completed.

  By performing this control, the display of the liquid crystal display panel and the light emission of the backlight can be normally associated over the entire screen, and an erroneous color can be prevented from being displayed.

  In FIG. 37, a sidelight type backlight in which a light source is arranged on the long side of the screen is used, but a light source may be arranged on the short side of the screen. In this case, the backlight can be scanned as in FIG. 15 of the first embodiment.

  According to the above-described embodiment, in a field sequential display device using a color filter together, it is possible to appropriately perform AC driving of the display panel and obtain a good image display without image quality degradation such as horizontal stripes.

  Furthermore, according to the above-described embodiment, it is possible to ensure the writing time of the pixels of the display panel in the display device. As a result, it is possible to suppress the occurrence of insufficient writing during high refresh rate driving and obtain a good image display.

  100 liquid crystal display device, 110 color filter, 110 upper frame, 120 lower frame, 131 first backlight, 132 second backlight, 200 liquid crystal display panel, 220 color filter substrate, 222 first color filter, 224 second Color filter, 230 TFT substrate, 310 backlight, 311 sub-pixel, 312 pixel, 320 data signal line driving circuit, 321 data voltage, 330 scanning signal line driving circuit, 331 scanning signal line selection signal, 340 timing control circuit, 341 data Signal line drive circuit control signal group, 342 output display data, 343 scanning signal line drive circuit control signal group, 344 backlight control signal group, 350 data conversion circuit, 351 conversion control signal group, 352 conversion display data, 360 backlight, 70 backlight drive circuit, 371 backlight drive signal group, 381 input control signal group, 382 input display data, 411 to 417 liquid crystal display panel, 510 backlight, 710 n double speed conversion circuit, 712 n double speed display data, 720 frame memory 730 field counter, 731 field counter value, 740 line counter, 741 line counter value, 750 dot counter, 751 dot counter value, 760 line memory, 761 line delay n double speed display data, 770 selector, 771 rearrangement display data, 780 Arithmetic circuit, 810 subpixel, 820 subpixel, 2100 frame, 2110 region, 2410 light guide plate, 2420 substrate.

Claims (8)

A liquid crystal display panel for controlling the orientation of the liquid crystal composition;
The liquid crystal display panel includes a backlight that alternately irradiates light of different colors with first backlight light and second backlight light,
The liquid crystal display panel is
A first pixel comprising two adjacent subpixels each having a different color filter;
A second pixel composed of two adjacent sub-pixels adjacent to the first pixel and having the different color filters, respectively.
In the inversion driving, in which the two sub-pixels of the first pixel are alternately written with the potential difference between the high-potential-side gradation voltage and the low-potential-side gradation voltage with respect to the reference potential, Is written,
The liquid crystal display device, wherein the two sub-pixels of the second pixel are written with a potential difference in phase opposite to that of the first pixel in the inversion driving.   The two subpixels of the first pixel and the two subpixels of the second pixel are on the same straight line parallel to the data signal line connected to the source or drain of the pixel transistor of the liquid crystal display panel. The liquid crystal display device according to claim 1, wherein the liquid crystal display devices are arranged side by side. The two subpixels of the first pixel and the two subpixels of the second pixel are arranged on the same straight line parallel to the scanning signal line connected to the gate of the pixel transistor of the liquid crystal display panel. are, the liquid crystal display device according to claim 1 or 2, characterized in that. Of the two sub-pixels, one sub-pixel has a first field that is a scanning period in which gradation data corresponding to the first backlight light is sequentially written for each line, and a floor corresponding to the second backlight light. 4. The gradation data is written only in any one of the second fields, which is a scanning period in which tone data is sequentially written for each line . The liquid crystal display device according to one item . Area of the color filters of the two sub-pixels, wherein the color emitted from the sub-pixel is determined based on the period of light emitted through the color filter, any of claims 1 to 4, characterized in that the liquid crystal display device according to an item or. In the liquid crystal display panel, the first field, which is a scanning period in which gradation data corresponding to the first backlight light is sequentially written for each line, and the gradation data corresponding to the second backlight light for each line. turn a writing scanning period and the second field, and overlap, it liquid crystal display device according to any one of claims 1 to 5, characterized in. The backlight divides an irradiation area into a plurality of areas, irradiates the first backlight light to an area where gradation data corresponding to the first backlight light is written, and corresponds to the second backlight light. as the the gradation data is written region second backlight light is irradiated, and controls so as to scan the irradiation area, it claimed in any one of claims 1 to 6, wherein Liquid crystal display device. The backlight is controlled to provide an extinguishing period in which no backlight is irradiated between the irradiation period of the first backlight light and the irradiation period of the second backlight light. The liquid crystal display device according to any one of claims 1 to 7 .

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