JP2009115968A - Method of driving liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of driving a liquid crystal display device that can suppress a color break. <P>SOLUTION: Disclosed is the method of driving the liquid crystal display device which is divided into 2n pieces (n: an integer of 2 to 4) having a plurality of continuous gate lines and provided with light sources of a plurality of colors for each of the areas, the method of driving the liquid crystal display device being characterized in that a write period, a liquid crystal response period, an illumination period, and an erasure period are provided in each sub-frame. By forming a set using any two areas of the 2n pieces of areas, the write periods are alternately provided by color for each area of each set, and the write periods are provided by pluralities of colors in order for each set of the 2n pieces of areas. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for driving a liquid crystal display device by a field sequential method.

  In recent years, color liquid crystal display devices have been actively developed. As a method for realizing color display, there are generally a color filter method and a field sequential method. In the color filter system, a white light source is used as a backlight, and color display is realized by attaching R, G, B micro color filters to each pixel. On the other hand, in the field sequential method, the backlight is switched in time with R, G, B, R, G, B, etc., and the black and white shutter of the liquid crystal is opened and closed in synchronization with it, and the color is timed by the afterimage effect of the retina. Thus, color display is realized. In this field sequential method, color display is possible with one pixel, and it is not necessary to use a color filter with low transmittance, so that bright and high-definition color display is possible, and low power consumption and low cost can be realized. It is useful in.

  Conventionally, in the field sequential method, after a plurality of gate lines are sequentially scanned and written, the plurality of gate lines are sequentially scanned and erased. Further, the light source is always turned on for the uniformity of image display. However, the luminance differs between the gate line scanned first and the gate line scanned last, and the liquid crystal is different from the color to be displayed due to the influence of the driving state of the liquid crystal in the immediately preceding subframe. There is a problem that colors are displayed and color reproducibility is lowered. Moreover, there is a problem that writing and erasing takes too much time if writing and erasing sequentially. In addition, the light source is turned on at the time of erasing, and there is a problem that the light from the light source cannot be used effectively.

Therefore, a driving method for writing a reset signal to all pixels at the end of each subframe and immediately before the next subframe has been proposed for the purpose of suppressing variations in luminance and color reproducibility at each pixel. (For example, refer to Patent Document 1 and Patent Document 2).
In addition, for the purpose of improving the light utilization efficiency, the light source is turned on after applying voltage to the last gate line for writing and immediately after erasing by applying voltage to the first gate line. A driving method for turning off the light has been proposed (see, for example, Patent Document 3).
Furthermore, for the purpose of increasing the light utilization efficiency and reducing the time required for erasing, voltage is applied to the liquid crystal by simultaneously selecting multiple pixel electrodes during the erasing process, and the light source is supplied to all pixel electrodes. A driving method for lighting only after writing scanning has been proposed (see, for example, Patent Document 4).

  In the field sequential method, light sources of multiple colors are turned on sequentially, so when displaying a fast moving movie, the phenomenon that the colors appear to be separated, the so-called color break, occurs and the image quality is significantly reduced. is there. In order to solve this problem, as described above, when the light source is turned on after writing to all the gate lines, the interval between the lighting periods of the light sources of a plurality of colors may be shortened.

  Further, in the liquid crystal display device, as a method of reducing outline blurring when displaying a moving image, a method of dividing a display area into a plurality of parts and sequentially turning on a light source for each light emission divided area corresponding to the plurality of divided display areas Has been proposed (see, for example, Patent Document 5 and Patent Document 6).

JP-A-5-265403 JP 2004-206003 A JP 2001-235766 A JP 2003-5153 A JP 2004-62134 A JP 2002-82326 A

  When sequentially turning on the light source for each light-emitting divided area and writing the RGB three-color image data one by one in all the divided display areas, the red image data is sequentially written in all the divided display areas, and then all The green image data is sequentially written in the divided display areas, and the blue image data is sequentially written in all the divided display areas. In this case, it is possible to shorten the time required to write the RGB three-color image data in all the divided display areas as compared with the above case. However, it is difficult to shorten the interval between the lighting periods of the light sources of a plurality of colors.

  The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a driving method of a liquid crystal display device capable of suppressing a color break.

  In order to achieve the above object, the present invention provides a liquid crystal that is divided into 2n (n is an integer of 2 to 4) regions having a plurality of continuous gate lines, and a light source of a plurality of colors is provided in each region. In the display device driving method, a voltage is sequentially applied to a plurality of gate lines in the one region in each subframe to sequentially turn on a plurality of switching elements, and a plurality of source lines have a first A writing period in which a voltage of polarity is applied, a liquid crystal response period in which the ferroelectric liquid crystal waits for a response after the writing period, and a light source of one color provided in the region is turned on after the liquid crystal response period After the lighting period and after the lighting period, a voltage is simultaneously applied to the plurality of gate lines in the region to simultaneously turn on the plurality of switching elements, and simultaneously to the plurality of source lines opposite to the first polarity. An erasing period in which either the second polarity voltage or the zero voltage is applied, and any two of the 2n regions are defined as one set, and each region in each set region A driving method of a liquid crystal display device is provided, in which writing periods are alternately provided for each color, and writing periods are sequentially provided for each group in 2n regions.

  According to the present invention, any two regions out of 2n regions obtained by dividing a plurality of gate lines are set as one set, and writing periods are alternately provided for each region in each set region, Since the writing period is sequentially provided for each set in the 2n regions, the interval between the lighting periods of the light sources of the plurality of colors can be shortened, and the color break can be suppressed.

  In the above invention, the writing period is preferably equal to or longer than a total time of the liquid crystal response period, the lighting period, and the erasing period. This is because since the writing period is equal to or longer than the total time of the liquid crystal response period, the lighting period, and the erasing period, writing scanning can be performed efficiently.

  In the present invention, after the writing period of a certain region, a voltage is simultaneously applied to a plurality of gate lines in a region other than the region to simultaneously turn on the plurality of switching elements, and the plurality of source lines May have a first initialization period in which a zero voltage is applied simultaneously. This is because when the liquid crystal having spontaneous polarization is used, the charge amount of each pixel can be equalized by providing the first initialization period a plurality of times in one frame. As a result, it is possible to prevent the charge balance from deteriorating and the liquid crystal response from deteriorating.

  Further, in the present invention, after the erasing period of the last subframe in one frame, at least the above-described switching elements are turned on at the same time while simultaneously applying voltages to the plurality of gate lines in the one region. You may have the 2nd initialization period which applies and hold | maintains a zero voltage simultaneously to a several source line. In the second initialization period, the time for applying the voltage to the plurality of gate lines simultaneously is set longer than the time required for the liquid crystal response. When a liquid crystal having spontaneous polarization is used, the charge amount of each pixel can be equalized by turning on the gate line longer than the response time of the liquid crystal in the second initialization period. is there. As a result, it is possible to prevent the charge balance from deteriorating and the liquid crystal response from deteriorating.

  In the above case, in the second initialization period, the second source period is simultaneously applied to the plurality of source lines while simultaneously applying voltages to the plurality of gate lines in the one region and simultaneously turning on the plurality of switching elements. After the reverse polarity voltage initialization period for applying and holding a voltage of the polarity and after the reverse polarity voltage initialization period, the plurality of switching elements are applied by simultaneously applying voltages to the plurality of gate lines in the one region. A zero voltage initialization period in which a zero voltage is simultaneously applied to and held in the plurality of source lines while being turned on at the same time may be provided. This is because the charge amount of each pixel can be equalized.

  In the present invention, after the erasing period of the last subframe in one frame, the plurality of switching elements are simultaneously turned on by simultaneously applying voltages to the plurality of gate lines in the one region, and A reverse polarity voltage holding period for simultaneously applying and holding the voltage of the second polarity to the source lines may be provided. There is a reverse polarity voltage holding period after the erasing period of the last subframe, and in this reverse polarity voltage holding period, the liquid crystal in each pixel is simultaneously reversed to the polarity of the applied voltage in the writing period. This is because the voltage of the second polarity is applied and held, so that the bias of charge can be suppressed and burn-in can be prevented.

Furthermore, in the present invention, after the erasing period of the last subframe in one frame, the plurality of switching elements are simultaneously turned on by simultaneously applying voltages to the plurality of gate lines in the one region, and A first holding period in which the voltage of the first polarity is simultaneously applied to the source line and held therein, a voltage is simultaneously applied to the plurality of gate lines in the region to simultaneously turn on the plurality of switching elements, and You may have the alternating voltage application period which has alternately the 2nd holding | maintenance period which applies and hold | maintains the said 2nd polarity voltage simultaneously to a several source line. In this case, it is preferable that the first holding period of a certain region is provided other than the lighting period of the region adjacent to the region, and the data written in the writing period and the data written in the alternating voltage application period are different. .
There is an alternating voltage application period after the erase period of the last subframe. During this alternating voltage application period, the voltages of the first polarity and the second polarity, which are opposite in polarity, are alternately applied to the liquid crystal in each pixel. This is because, when a still image is displayed for a long time, it is possible to suppress the bias of electric charges and prevent burn-in. In addition, since the data to be written in the writing period is different from the data to be written in the alternating voltage application period, the charge bias can be effectively suppressed.

  In the above case, it is preferable that the data to be written in the alternating voltage application period is randomly different for each frame. This is because the bias of charge can be further suppressed.

  In the present invention, the scanning order in the writing period of the previous subframe and the scanning order in the writing period of the next subframe may be reversed. This is because the time during which a voltage is applied between the electrodes of the pixels along each gate line can be averaged.

  Furthermore, in the present invention, when the writing period of a certain area overlaps with the lighting period of the area adjacent to this area, the writing period of the certain area is adjacent to this area. You may scan from the said gate line located in the opposite side to the side in which the area | region to provide is provided. This is because light leakage can be prevented.

  In the present invention, it is preferable to use a ferroelectric liquid crystal that exhibits monostability and exhibits half V-shaped switching characteristics. When a ferroelectric liquid crystal exhibiting monostable and half V-shaped switching characteristics is used, the aperture time as a black and white shutter can be made sufficiently long, and a bright color display liquid crystal display device can be obtained. This is because it can be realized.

  In the present invention, a plurality of gate lines divided into 2n (n is an integer of 2 to 4) regions, a plurality of source lines, and the gate lines and the source lines are connected to each other and arranged for each pixel. A plurality of switching elements, a plurality of pixel electrodes connected to the switching elements and disposed for each pixel, a counter electrode disposed at a position facing the pixel electrodes, and disposed between the pixel electrode and the counter electrode A liquid crystal panel including a liquid crystal panel, a gate driver connected to the plurality of gate lines and applying a scanning signal, and a source driver connected to the plurality of source lines and applying an image signal, and the liquid crystal panel A plurality of color light sources provided for each region, and the gate driver, the source driver, and the light source connected to the above-described liquid crystal display device. To provide a liquid crystal display device characterized by having a control unit for driving the liquid crystal display device by.

  Since the liquid crystal display device of the present invention is driven by the above-described driving method of the liquid crystal display device, the interval between lighting periods of a plurality of light sources can be shortened, and color breaks can be suppressed.

  In the present invention, any two regions out of 2n regions obtained by dividing a plurality of gate lines are set as one set, and writing periods are alternately provided for each region in each set region. Since the writing period is sequentially provided for each set in each region, a color break can be suppressed.

  Hereinafter, the driving method and the liquid crystal display device of the liquid crystal display device of the present invention will be described in detail.

A. Method for Driving Liquid Crystal Display Device The method for driving a liquid crystal display device according to the present invention is divided into 2n (n is an integer of 2 to 4) regions having a plurality of continuous gate lines, and light sources of a plurality of colors are provided for each region. In each subframe, a voltage is sequentially applied to a plurality of gate lines in the one region to sequentially turn on a plurality of switching elements and a plurality of sources. A writing period in which a voltage having a first polarity is applied to the line; a liquid crystal response period in which the ferroelectric liquid crystal waits for a response after the writing period; and one color provided in the region after the liquid crystal response period A lighting period for turning on the light source, and after the lighting period, simultaneously applying a voltage to the plurality of gate lines in the region to turn on the plurality of switching elements at the same time, and simultaneously applying the voltage to the plurality of source lines. An erasing period in which either a second polarity voltage or a zero voltage having a polarity opposite to the first polarity is applied, and any two of the 2n regions as a set, The writing period is alternately provided for each region in each set of regions, and the writing period is sequentially provided for each group in a plurality of colors in 2n regions.

The driving method of the liquid crystal display device of the present invention will be described with reference to the drawings.
FIG. 1 is a circuit diagram of a liquid crystal display device. The circuit illustrated in FIG. 1 includes j rows of gate lines G ₁ , G ₂ ,... G _j and k columns of source lines S ₁ , S _{2 ,.} , J row gate lines G ₁ , G ₂ ,... G _j , and k column source lines S ₁ , S _{2 ,.} . These gate lines _{G 1, G 2, ... G} j and a source line _{S 1,} S 2, ... in each pixel in the vicinity of each intersection of _{S k,} gate lines _{G 1, G 2, ... G} j and Switching elements 4 are arranged in a state of being connected to the source lines S ₁ , S ₂ ,... S _k , and pixel electrodes 5 are connected to the respective switching elements 4.

  The gate driver applies a voltage to the gate line (supplying a scanning signal), and the source driver applies a positive or negative voltage to the source line (supplying an image signal). At this time, an image signal corresponding to one unit color among a plurality of unit colors for displaying an arbitrary color by mixed color is supplied to the source line. As a result, the gate driver sequentially applies voltages to the plurality of gate lines to sequentially turn on the plurality of switching elements in units of gate lines, and the source driver applies positive or negative voltage to the plurality of source lines. The liquid crystal is driven by applying a positive or negative voltage to the liquid crystal via the switching element and the pixel electrode. That is, a voltage corresponding to the image signal is applied between the pixel electrode and the counter electrode of the pixel along each gate line, and image data is written to each pixel along the gate line, and depending on the degree of response of the liquid crystal to this, The light transmittance of each pixel is controlled.

  FIG. 2 is a timing chart showing an example of a method for driving a liquid crystal display device by a field sequential method using the circuit diagram shown in FIG. As the liquid crystal, a ferroelectric liquid crystal in which liquid crystal molecules operate only when a positive voltage is applied as illustrated in FIG. 3B is used.

In FIG. 2, Scan schematically shows a state in which m rows of gate lines G ₁ , G ₂ ,... G _m in each region are scanned, and the LED indicates the lighting timing of the light source (RGB three-color light source). It is shown. In addition, a period in which one full-color still image is displayed is 1 frame F, and a period in which one RGB still image is displayed is a subframe SF _R , SF _G , SF _B.

As shown in FIG. 1, j rows of gate lines G ₁ , G ₂ ,... G _j are divided into _four regions A _{1 to} A ₄ for each m rows. A color light source is provided. The four areas A _{1 to} A ₄ are a set of two adjacent areas as illustrated in FIG. Here, two adjacent areas A ₁ and A ₂ are set as a first set, and two adjacent areas A ₃ and A ₄ are set as a second set. Then, a writing period is alternately provided for each region in each set of regions, and a writing period is sequentially provided for each group in a plurality of colors in 2n regions.

First, in the first set of regions _{A 1,} in subframe SF _R, gate lines _G 1 m rows by the gate driver _2, G 2, ... and a voltage from the m-th row in the order of the first row is applied to _{G m} a plurality of switching elements 4 as well as on the order in the gate line basis, the source lines S ₁ k columns by the source driver _3, S 2, _... applies a positive voltage to S _k, the switching element 4 and the pixel electrode 5 The liquid crystal is driven by applying a positive voltage to the liquid crystal. In this manner, voltages are sequentially applied to a plurality of gate lines in one region to sequentially turn on the plurality of switching elements, and the first polarity is applied to the plurality of source lines (positive polarity in FIG. 2). period for applying a voltage is a write period T _a.

Next, a voltage is applied to the last gate line G ₁ by the gate driver 2 to turn on the switching element 4 along the gate line G _1, and the source lines S ₁ , S ₂ ,. A positive voltage is applied to _Sk and a positive voltage is applied to the liquid crystal via the switching element 4 and the pixel electrode 5 to drive the liquid crystal. At this time, the liquid crystal of the pixel in the m-th row to which the voltage has been applied first has already sufficiently responded since the time has passed sufficiently. Therefore, to the liquid crystal along the gate lines G ₁ of the first row responds, it is necessary to wait. Thus, the period of waiting for the liquid crystal to respond to the last row after the writing period is a liquid crystal response period T _b.

Then, after the liquid crystal response period T _b, after the liquid crystal is fully driven in pixels along the end of the gate lines G _1, by irradiating predetermined time the red light R from the red light source, so that the red image is recognized To. Thus, the period during which the light source is turned on after the liquid crystal response period is the lighting period _Tc .

Then, the gate lines _{G 1,} G 2 of the m rows, ... with simultaneously on a plurality of the switching elements 4 and simultaneously applying a voltage to the _{G m,} the source lines _S 1 of k _columns, S 2, ... _{S k} simultaneously A negative voltage is applied to reset the driving state of the liquid crystal. As described above, after the lighting period, a plurality of switching elements are simultaneously turned on by simultaneously applying a voltage to a plurality of gate lines in one region, and a second polarity voltage or a zero voltage is simultaneously applied to a plurality of source lines. A period during which any one of the negative voltages is applied in FIG. 2 is an erasing period _Td .
At this time, because it is being written in the image data of the red in the area A _2, a moment, the writing scanning area A ₂ is interrupted.

Then, even in the sub-frame SF _G and SF _B, similarly to the sub-frame SF _R, performs writing, the liquid crystal response, lighting, and erasing. Then, it is a non-selection period T _h.

In the first group A ₂ , writing, liquid crystal response, lighting, erasing, writing, liquid crystal response, lighting, erasing, writing, liquid crystal response, lighting, and erasing are performed in the same manner as the area A _1. Not selected.

In the first set of areas _A 1, _{A 2,} following the writing period _{T a} of the sub-frame SF _R region _{A 1,} the writing period _{T a} of the sub-frame SF _R regions _{A 2} are provided. Moreover, following the writing period _{T a} of the sub-frame SF _R regions _{A 2,} the writing period _{T a} of the sub-frame SF _G region _{A 1} is provided. That is, the write period, region subframe _{A 1} SF writing period _{R T a,} the writing period _{T a} of the sub-frame SF _R area _{A 2,} the area _{A 1} of the sub-frame SF writing period of _{G T a,} the area A write period of the _second subframe SF _{G T a,} the writing period of the sub-frame SF _B region _{a 1 T a,} are provided in the order of writing period _{T a} of the sub-frame SF _B region _{a 2.}
In this way, in each set of areas, red image data is first written in two areas in order, then green image data is sequentially written in two areas, and finally blue image data is written in two areas. They are written in order. That is, the writing period is alternately provided for each region in each set of regions.

Further, in the second set area A ₃ , writing, liquid crystal response, lighting, erasing, writing, liquid crystal response, lighting, erasing, writing, liquid crystal response, lighting and erasing are performed in the same manner as the first set area A _1. Followed by deselection.
Further, in the second set area A ₄ , similarly to the first set area A ₁ , writing, liquid crystal response, lighting, erasing, writing, liquid crystal response, lighting, erasing, writing, liquid crystal response, lighting and erasing are performed. Followed by deselection.

In the second set of regions _A 3, _{A 4,} similarly to the first set of regions _A 1, _{A 2,} writing period, the area _{A 3} of the sub-frame SF _R writing period _{T a,} the sub-frame region _{A 4} SF writing period _{R T a,} the writing period of the sub-frame SF _G area _{a 3 T a,} the writing period _{T a} of the sub-frame SF _G area _{a 4,} area _{a 3} of the sub-frame SF _B writing period _T a, It is provided in order of the writing period _{T a} of the sub-frame SF _B area _{a 4.}

Furthermore, in the first set of regions _{A 2} and the second set of regions _{A 3,} following the writing period _{T a} region _{A 2} of the sub-frame SF _B, subframe area _{A 3} SF writing period _{R T a} Is provided. Also, a second set of regions _{A 4} in the first set of regions _{A 1} and, following the writing period _{T a} of the sub-frame SF _B area _{A 4,} subframe areas _{A 1} SF writing period _{R T a} Is provided. That is, the write period, region subframe _{A 1} SF writing period _{R T a,} the writing period _{T a} of the sub-frame SF _R regions _{A 2,} area _{A 1} of the sub-frame SF writing period of _{G T a,} the area A ₂ subframe SF _G write period T _a , area A ₁ subframe SF _B write period T _a , area A ₂ subframe SF _B write period T _a , area A ₃ subframe SF _R write period _{T a,} the writing period of the sub-frame SF _R region _{a 4 T a,} the writing period _{T a} of the sub-frame SF _G area _{a 3,} the area _{a 4} subframes SF _G writing period _{T a,} the area _{a 3} writing period of the sub-frame SF _{B T a,} it is repeatedly arranged in the order of writing period _{T a} of the sub-frame SF _B area _{a 4.}
In this way, the three color image data are sequentially written in the first set of areas, and then the three color image data are sequentially written in the second set of areas. That is, the writing period is provided in order of plural colors for each group in 2n areas.

  In one area, the color of light emitted from a light source through a series of driving (writing, liquid crystal response, lighting, erasing, writing, liquid crystal response, lighting, erasing, writing, liquid crystal response, lighting, erasing, and non-selection) Repeatedly changing RGB and the image to be displayed. In one set of areas, image data is written for each color. Then, in 2n areas, image data is written in three colors of RGB for each set. By repeating such a series of driving operations, images of different colors can be visually mixed and recognized as a full color image.

According to the present invention, an arbitrary two regions are set as one set, and a writing period is alternately provided for each region in each set of regions, and a writing period is provided for each group in a plurality of colors in 2n regions. Are provided in order, the intervals of the lighting periods of the light sources of the plurality of colors can be shortened, and color breaks can be suppressed. For example, in FIG. 2, in any of the areas A _{1 to} A ₄ , the interval between the lighting period T _c of the red R light source and the lighting period T _c of the green G light source, and the lighting period T of the green G light source. The interval between _c and the lighting period _Tc of the blue B light source can be shortened.

  On the other hand, for example, when writing periods are sequentially provided for each color in 2n areas, when writing image data of RGB three colors, red image data is sequentially written in 2n areas, and then 2n Since the green image data is sequentially written in this area, and then the blue image data is sequentially written in the 2n areas, it is difficult to shorten the intervals of the lighting periods of the three color light sources.

In the present invention, any two regions are set as one set, and writing periods are alternately provided for each region in each set region, and writing periods are provided for each group in a plurality of colors in 2n regions. When the image data of RGB three colors is written, the red image data is sequentially written in a certain set of areas (two areas), and then the green color is written in the set areas (two areas). Image data is written sequentially, then blue image data is written sequentially to the set of regions (two regions), and red image data is written sequentially to the next set of regions (two regions). Therefore, it is possible to shorten the interval between the lighting periods of the light sources of a plurality of colors.
The erasing period may be as short as the response time of the liquid crystal, and in the present invention, since the liquid crystal exhibiting high-speed response is used, the erasing period can be further shortened.
Therefore, in the present invention, color break can be suppressed.

In addition, since the erasing period is short, the time during which voltage is applied to the liquid crystal can be shortened, and image sticking can be suppressed.
In addition, there is an erasing period after the lighting period, and the driving state of the liquid crystal in each pixel is reset at the same time, thereby completely eliminating fluctuations in image display in the next subframe due to image display in the previous subframe. Therefore, it is possible to realize gradation display with good reproducibility.

In the present invention, as illustrated in FIG. 2, the writing period is preferably equal to or longer than the total time of the liquid crystal response period, the lighting period, and the erasing period. In this case, the liquid crystal response period, the lighting period, and the erasing period can be provided in the writing period.
For example, the first set of regions _A 1, _{A 2,} the liquid crystal response period _{T b} of the sub-frame SF _R region _{A 1,} the lighting period _{T c,} and erase period _{T d} is the area _{A 2} of the sub-frame SF _R It is provided in the writing period T _a. Similarly, the liquid crystal response period _{T b} of the sub-frame SF _G region _{A 1,} the lighting period _{T c,} and erase period _{T d} is provided in the writing period _{T a} of the sub-frame SF _G regions _{A 2,} area A liquid crystal response period _{T b} of the _first subframe SF _B, lighting period _{T c,} and erase period _{T d} are provided in the writing period _{T a} of the sub-frame SF _B region _{a 2.} That is, the writing period is equal to the total time of the liquid crystal response period, the lighting period, and the erasing period.
Thus, during the writing period in which image data of one color is written in a certain area, a liquid crystal response period, a lighting period, and an erasing period can be provided in another area. In one set of regions, a liquid crystal response period, a lighting period, and an erasing period can be provided in a writing period in which one color image data is written in one area. Therefore, the time during which writing scanning is not performed can be reduced or eliminated, and writing scanning can be performed efficiently.
In the present invention, since the driving state of the liquid crystal in each pixel is simultaneously reset in the erasing period, it does not take time to erase the image data written in each pixel in the writing period. Since the erasing period can be shortened in this way, the writing period can be made longer than the total time of the liquid crystal response period, the lighting period, and the erasing period.

  Hereinafter, each period in the driving method of the liquid crystal display device of the present invention and the liquid crystal used in the present invention will be described in detail.

1. Write period In the driving method of the liquid crystal display device of the present invention, in each subframe, voltages are sequentially applied to a plurality of gate lines in one region to sequentially turn on a plurality of switching elements, and to a plurality of source lines. A writing period for applying a voltage of the first polarity is provided.

  A voltage is sequentially applied to the gate lines row by row (a scanning signal is sequentially supplied) to set a selected state. That is, a plurality of gate lines in one region are scanned line-sequentially. A voltage having a first polarity (positive polarity or negative polarity) is applied to the source line (image signal is supplied). As a result, a voltage corresponding to the image signal is applied between the pixel electrode and the counter electrode of each pixel along the gate line, that is, a voltage corresponding to the difference between the pixel electrode and the counter electrode is applied to the liquid crystal. Is written to each pixel along the gate line. In each pixel, the liquid crystal responds according to the potential difference between the pixel electrode and the counter electrode. The light transmittance of each pixel is controlled by the degree of response of the liquid crystal.

  The first polarity voltage may be either positive or negative voltage.

The order of scanning in the writing period is not particularly limited.
For example, the scanning order in the writing period of the previous subframe and the scanning order in the writing period of the next subframe may be reversed.

FIG. 4 is a timing chart showing an example of a method for driving a liquid crystal display device by a field sequential method using the circuit diagram shown in FIG. 1, and shows the scanning order in the writing period of the previous subframe and the next subframe. This is an example in which the scanning order in the writing period is reversed. As the liquid crystal, a ferroelectric liquid crystal in which liquid crystal molecules operate only when a positive voltage is applied as illustrated in FIG. 3B is used. Moreover, the symbols in FIG. 4 are the same as the symbols in FIG.
In the example shown in FIG. 4, in the region _{A 1,} first, in the previous frame _{F 1,} at sub-frame SF _R, m-th row, the (m-1) row, the m-2 line, ..., the first row A voltage is sequentially applied to the gate line. Next, in the subframe SF _G , a voltage is applied to the gate lines in the order of the first row, the second row, the third row,. Subsequently, in the subframe SF _B , a voltage is applied to the gate lines in the order of the m-th row, the (m−1) -th row, the m-2th row,. Then, in the next frame F _2, at subframe SF _R, first row, second row, third row, ..., a voltage is applied to the gate line in the order of the m-th row. Then, although not shown in the sub-frame SF _R of the next frame F _2, the m-th row, the (m-1) row, the m-2 line, ..., a voltage is applied to the gate line in the order of the first row. Subsequently, in the sub-frame SF _G of the next frame F _2, the first row, second row, third row, ..., a voltage is applied to the gate line in the order of the m-th row.

  As described above, when the scanning order in the writing period of the previous subframe and the scanning order in the writing period of the next subframe are opposite, the pixel electrode and the counter electrode of the pixel along each gate line The time during which the voltage is applied can be averaged.

  In addition, for example, when the writing period of a certain region overlaps with the lighting period of a region adjacent to the region, the region adjacent to the region is changed in the writing period of the certain region. You may scan from the said gate line located in the opposite side to the side provided.

FIG. 5 is a timing chart showing an example of a method for driving a liquid crystal display device by a field sequential method using the circuit diagram shown in FIG. 1, and a region adjacent to this region is written in a writing period of a certain region. This is an example of scanning from a gate line located on the side opposite to the provided side. As the liquid crystal, a ferroelectric liquid crystal in which liquid crystal molecules operate only when a positive voltage is applied as illustrated in FIG. 3B is used. Further, the symbols in FIG. 5 are the same as the symbols in FIG.
In the example shown in FIG. 5, for example, for each write period T _a region A _3, a lighting period T _c of the writing period T _a and the area A ₂ of the sub-frame SF _B sub-frame SF _R region A ₃ duplicate and has, at the writing time period T _a of the sub-frame SF _R region a _3, the m-th row, the (m-1) row, the m-2 line, ..., and scan the gate lines in the order of the first row . That is, in the writing period in the region A _3, is scanning from the gate line located on the opposite side to the side where the area A ₂ that is adjacent to the region A ₃ is provided. Also, region and lighting period T _c of the sub-frame SF _R writing period of the sub-frame SF _G of A ₃ T _a and the area A ₄ is duplicated, the writing period of the sub-frame SF _B region A ₃ T _a and the area A a lighting period T _c of the _fourth sub-frame SF _G are duplicated, the sub-frame SF _G area a _3, in each writing period T _a of SF _B, the first row, second row, third row, ..., the gate lines are scanned in the order of the m-th row. That, in the writing period in the region A _3, is scanning from the gate line located on the side opposite to the side where the area A ₄ which are adjacent to the region A ₃ is provided. As a result, it is possible to prevent light leakage from occurring in the area A ₃ where writing scanning is performed while the light source is lit in the adjacent areas A ₂ and A ₄ .

  In this way, when the writing period of a certain region overlaps with the lighting period of a region adjacent to this region, a region adjacent to this region is provided in the writing period of a certain region. In the case of scanning from the gate line located on the opposite side to the side where the light is present, light leakage can be prevented.

The length of the writing period is not particularly limited, but the writing period is preferably equal to or longer than the total time of a liquid crystal response period, a lighting period, and an erasing period, which will be described later. This is because, as described above, writing scanning can be performed efficiently.
When the writing period is equal to or longer than the total time of the liquid crystal response period, the lighting period, and the erasing period, the writing period may be equal to the total time or longer than the total time. In particular, the writing time is preferably equal to the total time of the liquid crystal response period, the lighting period, and the erasing period. Accordingly, the liquid crystal response period, the lighting period, and the erasing period can be provided within the writing period, and conversely, the writing period can be provided within the period including the liquid crystal response period, the lighting period, and the erasing period. This is because scanning can be performed more efficiently.

  The writing period is appropriately selected according to the type of liquid crystal (liquid crystal response speed), the number of gate lines, and the like. For example, the writing time per gate line can be set to 4 μs to 8 μs.

  In the present invention, any two regions out of 2n regions are set as one set, and a writing period is alternately provided for each region in each set region, and 2n regions are provided for each set. Write periods are provided in order for each of a plurality of colors.

In each set of regions, it is only necessary to alternately provide a writing period for each color for each region. In a region where the writing period for the first color is performed first, a writing period for one color and a writing for the first color are performed later. The writing period of the color in the region where the period is performed may or may not be continuous. Among these, as shown in FIGS. 2 and 4, it is preferable that these writing periods are provided continuously. 2 and FIG. 4, for example, in the first set of regions _A 1, _{A 2,} and the writing period _{T a} of the sub-frame SF _R region _{A 1,} the writing period _{T a} of the sub-frame SF _R region _{A 2} Is continuous. Thereby, the interval of each lighting period of the light source of a several color can be shortened, and a color break can be suppressed effectively.

  Further, in the 2n regions, it is only necessary to provide a plurality of colors for each group in order, and the last writing period of the previous group and the first writing period of the next group are continuous. May not be continuous.

2. Liquid crystal response period In the driving method of the liquid crystal display device of the present invention, the liquid crystal responds during each subframe as the time when the liquid crystal response is almost completed in the pixel along the gate line scanned last after the writing period. It has a liquid crystal response period for waiting.

  The liquid crystal response period is appropriately selected according to the type of liquid crystal (liquid crystal response speed), the potential difference between the applied voltage immediately before the writing period and the applied voltage in the writing period, and the like. For example, the liquid crystal response period can be set from 100 μs to 1000 μs.

3. Lighting Period The driving method of the liquid crystal display device of the present invention has a lighting period in which a light source of one color provided in one region is lit after each liquid crystal response period in each subframe.

As the light source, a light source of a plurality of colors is used. For example, a light source configured to selectively irradiate light of two colors or more, preferably 3 to 5 colors, is used.
The light source (backlight) can be either a side edge type or a direct type. In the case of the direct type, in the method for driving the liquid crystal display device of the present invention, the partition in the vertical direction (source line direction) is not essential.

  The lighting period is appropriately selected according to the length of a writing period, a reverse polarity voltage holding period, which will be described later, or an alternating voltage application period.

4). Erase period In the driving method of the liquid crystal display device of the present invention, a plurality of switching elements are simultaneously turned on by simultaneously applying voltages to a plurality of gate lines in one region after a lighting period in each subframe. And an erasing period in which either a voltage having a second polarity opposite to the first polarity or a zero voltage is applied to the source lines simultaneously.

  A voltage is applied to the gate lines all at once (a scanning signal is supplied) to select the gate line. In addition, a voltage having a second polarity (positive or negative polarity) or zero voltage is applied to the source line (a reset signal is supplied). Thereby, a voltage corresponding to the reset signal is applied between the pixel electrode and the counter electrode of all the pixels, and the reset data is written to all the pixels.

  Whether to apply the second polarity voltage or the zero voltage is appropriately selected according to the type of liquid crystal. For example, when using a ferroelectric liquid crystal having a half V-shaped switching characteristic as described later, a voltage of the second polarity can be applied. For example, when using a ferroelectric liquid crystal or a nematic liquid crystal exhibiting V-shaped switching characteristics as described later, a zero voltage can be applied. In particular, not only the type of liquid crystal, but it is preferable to apply a zero voltage after applying a voltage of the second polarity. This is because the response speed (falling) of the liquid crystal can be increased and the operation start positions of the liquid crystal can be aligned.

  The voltage of the second polarity may be a voltage having a polarity opposite to that of the first polarity, and may be a positive voltage or a negative voltage.

  The erasing period is usually set on the order of μs to ms.

5). First initialization period In the driving method of the liquid crystal display device of the present invention, after the writing period of a certain region, a voltage is simultaneously applied to a plurality of gate lines in a region other than the region so that the plurality of switching elements are You may have the 1st initialization period which applies a zero voltage simultaneously to the said several source line while turning on simultaneously.

  FIG. 6 is a timing chart showing an example of a method for driving a liquid crystal display device by a field sequential method using the circuit diagram shown in FIG. As the liquid crystal, a ferroelectric liquid crystal in which liquid crystal molecules operate only when a positive voltage is applied as illustrated in FIG. 3B is used. The symbols in FIG. 6 are the same as the symbols in FIG. 2, and the thick line in FIG. 6 indicates the timing when the gate line is turned on.

First, in the area A ₁ , in the sub-frame SF _R of the frame F ₁ , a voltage is applied to the m rows of gate lines in the order from the first row to the m-th row to turn on the plurality of switching elements in units of gate lines. Then, a positive voltage is applied to the k-th source lines, and a positive voltage is applied to the liquid crystal via the switching element and the pixel electrode to drive the liquid crystal (writing period T _a ). Next, in the regions A ₂ , A ₃ , and A ₄ other than the region A ₁ , a voltage is simultaneously applied to the m rows of gate lines to simultaneously turn on the plurality of switching elements and simultaneously zero to the k column source lines. A voltage is applied (first initialization period T _g ). Next, after the first initialization period _Tg , a liquid crystal response period _Tb is provided as a liquid crystal response time (rise time). Next, after the liquid crystal in the pixels along the last gate line is driven, the red light R is emitted from the red light source for a predetermined time so that the red image is recognized (lighting period T _c ). Next, a voltage is simultaneously applied to the m-th row gate lines to simultaneously turn on the plurality of switching elements, and a negative polarity voltage is simultaneously applied to the k-column source lines to reset the driving state of the liquid crystal (erasing period). _Td ).

Next, in the subframe SF _G of the frame F _{1 in} the area A ₁ , writing is performed in the same manner as in the subframe SF _R. Subsequently, in the regions A ₂ , A ₃ and A ₄ other than the region A ₁ , a voltage is simultaneously applied to the m rows of gate lines to simultaneously turn on the plurality of switching elements and simultaneously zero to the k column source lines. A voltage is applied (first initialization period T _g ). Then, similarly to the subframe SF _R , liquid crystal response, lighting and erasing are performed.
Then, in the sub-frame SF _B of frames F ₁ in the area A _1, similarly to the sub-frame SF _R, performs writing. Subsequently, in the regions A ₂ , A ₃ and A ₄ other than the region A ₁ , a voltage is simultaneously applied to the m rows of gate lines to simultaneously turn on the plurality of switching elements and simultaneously zero to the k column source lines. A voltage is applied (first initialization period T _g ). Then, similarly to the subframe SF _R , liquid crystal response, lighting and erasing are performed.

In the areas A ₂ , A ₃ , and A ₄ , the writing, the initialization of other areas, the liquid crystal response, the lighting and the erasing are repeated in the same manner as the area A ₁ with a predetermined period of time.
In this case, during the non-selection period T _h, the first initialization period T _g is provided a plurality of times.

As described above, when the first initialization period is provided after the writing period of a certain region, the first initialization period in which the zero voltage is applied a plurality of times in one frame is provided. Can be removed.
Hereinafter, this reason will be described.
That is, the ferroelectric liquid crystal has spontaneous polarization. When the ferroelectric liquid crystal is operated by applying a voltage during the writing period, the direction of spontaneous polarization is reversed. In each pixel, the charge is reduced by the polarization of the ferroelectric liquid crystal. Then, when the ferroelectric liquid crystal is operated by applying a reverse polarity voltage in the erasing period after the lighting period, the direction of spontaneous polarization is reversed again. In each pixel, as in the writing period, the charge is reduced by the polarization of the ferroelectric liquid crystal. In this way, even when the same voltage is applied, the charge is reduced in the bright display area and the voltage is not sufficiently applied, resulting in a charge bias, and the ferroelectric liquid crystal compared to the other areas. Responsiveness may be reduced.
On the other hand, by providing a first initialization period in which a zero voltage is applied a plurality of times in one frame, the polarization of the ferroelectric liquid crystal is reversed even when the ferroelectric liquid crystal operates and the direction of spontaneous polarization is reversed. Thus, charges that compensate for the reduced charge are supplied, so that the charge amount can be equalized in all pixels. As a result, it is possible to prevent the response of the ferroelectric liquid crystal from being lowered.

  The reason why the zero voltage is applied all at once in the area other than the area where writing is performed is that the written image data changes if the zero voltage is applied also to the area where writing is performed.

6). Second initialization period In the driving method of the liquid crystal display device of the present invention, after the erasing period of the last subframe in one frame, a voltage is simultaneously applied to the plurality of gate lines in the one region to You may have the 2nd initialization period which applies and hold | maintains a zero voltage to at least said several source line simultaneously with a switching element turned ON simultaneously. In the second initialization period, the time for applying the voltage to the plurality of gate lines simultaneously is set longer than the time required for the liquid crystal response.

  FIG. 7 is a timing chart showing an example of a method of driving a liquid crystal display device by a field sequential method using the circuit diagram shown in FIG. As the liquid crystal, a ferroelectric liquid crystal in which liquid crystal molecules operate only when a positive voltage is applied as illustrated in FIG. 3B is used. The symbols in FIG. 7 are the same as the symbols in FIG. 2, the thick line in FIG. 7 indicates the timing for turning on the gate line, and the thick frame in FIG. 7 indicates the time for applying a voltage to the gate line. Show.

First, in the area A ₁ , in the sub-frame SF _R of the frame F ₁ , a voltage is applied to the m rows of gate lines in the order from the first row to the m-th row to turn on the plurality of switching elements in units of gate lines. Then, a positive voltage is applied to the k-th source lines, and a positive voltage is applied to the liquid crystal via the switching element and the pixel electrode to drive the liquid crystal (writing period T _a ). Next, after the first initialization period _Tg , a liquid crystal response period _Tb is provided as a liquid crystal response time (rise time). Next, after the liquid crystal in the pixels along the last gate line is driven, the red light R is emitted from the red light source for a predetermined time so that the red image is recognized (lighting period T _c ). Next, a voltage is simultaneously applied to the m-th row gate lines to simultaneously turn on the plurality of switching elements, and a negative polarity voltage is simultaneously applied to the k-column source lines to reset the driving state of the liquid crystal (erasing period). _Td ).

Next, in the subframe SF _G of the frame F ₁ , writing is performed in the same manner as in the subframe SF _R. Subsequently, in the regions A ₂ , A ₃ and A ₄ other than the region A ₁ , a voltage is simultaneously applied to the m rows of gate lines to simultaneously turn on the plurality of switching elements and simultaneously zero to the k column source lines. A voltage is applied (first initialization period T _g ). Then, similarly to the subframe SF _R , liquid crystal response, lighting and erasing are performed.
Then, in the sub-frame SF _B frames F _1, as with the sub-frame SF _R, performs writing. Subsequently, in the regions A ₂ , A ₃ and A ₄ other than the region A ₁ , a voltage is simultaneously applied to the m rows of gate lines to simultaneously turn on the plurality of switching elements and simultaneously zero to the k column source lines. A voltage is applied (first initialization period T _g ). Then, similarly to the subframe SF _R , liquid crystal response, lighting and erasing are performed.

Next, while simultaneously applying a voltage to the m-th row gate lines and simultaneously turning on the plurality of switching elements, a voltage of the second polarity is simultaneously applied to the k-column source lines and is held. A zero voltage is simultaneously applied to the line and held (second initialization period T _i ). In this case, during the non-selection period T _h, a second initialization period T _i is provided.

The timing chart of the region A ₁ shown in FIG. 7 is shown in FIG. In FIG. 8, Scan schematically shows a state in which m rows of gate lines in one region are sequentially scanned, and V _g1 ,... V _gm indicate timings at which voltages are respectively applied to the gate lines. Yes, V _LC indicates a change in voltage applied to the liquid crystal, and T _{1 to} T _m indicate a change in transmittance (that is, the driving state of the liquid crystal) in the pixels along each gate line. The LED indicates the lighting timing of the light source (RGB three-color light source). In addition, a period in which one full-color still image is displayed is 1 frame F, and a period in which one RGB still image is displayed is a subframe SF _R , SF _G , SF _B.

In the second initialization period T _i , as illustrated in FIG. 8, the voltage is simultaneously applied to the m rows of gate lines and the plurality of switching elements are simultaneously turned on, and the second column is simultaneously applied to the k column source lines. A polarity voltage is applied and held (reverse polarity voltage initialization period T _i1 ), and a plurality of switching elements are simultaneously turned on by simultaneously applying a voltage to the m rows of gate lines, and simultaneously to the k column source lines. A zero voltage is applied and held (zero voltage initialization period T _i2 ).

In the areas A ₂ , A ₃ , and A ₄ , the writing, liquid crystal response, lighting, and erasing are repeated and the initialization is performed similarly to the area A ₁ with a predetermined period of time.

As described above, by providing the second initialization period in which at least the zero voltage is applied and held while the gate line is turned on, the accumulated charge can be discharged reliably and the driving can be performed more stably. .
This is because when a liquid crystal having spontaneous polarization, such as a ferroelectric liquid crystal, is used, the liquid crystal operates and is spontaneously provided by providing a second initialization period in which at least zero voltage is applied and held while the gate line is turned on. This is because, even when the direction of polarization is reversed, the charge that compensates for the reduced charge due to the polarization of the liquid crystal is supplied, so that the amount of charge can be equalized in all pixels. As a result, it is possible to prevent the liquid crystal response from being lowered.

7). Reverse polarity voltage holding period In the driving method of the liquid crystal display device of the present invention, after the erasing period of the last subframe in one frame, a plurality of switching elements are applied by simultaneously applying voltages to a plurality of gate lines in one region. You may have the reverse polarity voltage holding | maintenance period which turns on simultaneously and applies and hold | maintains the voltage of a 2nd polarity simultaneously to a several source line. This reverse polarity voltage holding period is provided only once in one frame. Note that this reverse polarity holding period is not provided when an alternating voltage application period described later is provided.

  When a second polarity voltage is applied simultaneously to a plurality of source lines during the erasing period of the last subframe in one frame, the second polarity voltage is held as it is in the reverse polarity voltage holding period. . On the other hand, when zero voltage is simultaneously applied to a plurality of source lines in the erase period of the last subframe in one frame, voltages are simultaneously applied to a plurality of gate lines in the reverse polarity voltage holding period. The plurality of switching elements are simultaneously turned on, and the second polarity voltage is simultaneously applied to the plurality of source lines and held.

The timing chart of the region A ₁ shown in FIG. 4 shown in FIG. In Figure 9, Scan gate lines _G 1 m rows of one _region, G 2, and illustrates a state of scanning the ... _{G m} sequentially _{schematically, V g1,} ... _{V gm} gate lines _{G 1} , G ₂ ,... G _m indicate timings of applying voltages, V _LC indicates changes in voltage applied to the liquid crystal, and T _{1 to} T _m indicate pixels along each gate line. A change in transmittance (that is, a driving state of the liquid crystal) is indicated, and an LED indicates a lighting timing of the light source (RGB three-color light source). In addition, a period in which one full-color still image is displayed is 1 frame F, and a period in which one RGB still image is displayed is a subframe SF _R , SF _G , SF _B.

First, in the sub-frame SF _R, by applying a voltage sequentially to the plurality of gate lines as well as on the plurality of switching elements in order in the gate line basis, by applying a voltage of positive polarity (+) to a plurality of source lines, The liquid crystal is driven by applying a positive (+) voltage to the liquid crystal through the switching element and the pixel electrode (writing period T _a ). Next, after the writing period Ta, _a liquid crystal response period _Tb is provided as a liquid crystal response time (rise time). Next, after the liquid crystal in the pixels along the last gate line is driven, red light R is emitted from the red light source for a certain period of time so that a red image is recognized (lighting period T _c ). Next, a voltage is simultaneously applied to the plurality of gate lines to simultaneously turn on the plurality of switching elements, and a negative (−) voltage is simultaneously applied to the plurality of source lines to reset the driving state of the liquid crystal (erase) Period T _d ).
Then, in the sub-frame SF _G, writing scanning the gate lines from the first row in reverse order of the m-th row to the scan order in the sub-frame SF _R, the liquid crystal responds as the sub-frame SF _R, Turn on and erase. Next, in the sub-frame SF _B, similarly to the sub-frame SF _R, the writing scanning the gate lines from the m-th row in the order of the first row, perform liquid crystal response, lighting and erasing.
Next, the negative-polarity (-) voltage is applied to the plurality of source lines (reverse polarity voltage holding period T _e ).

  As described above, by providing the reverse polarity voltage holding period only once after the erasing period of the last subframe in one frame, it is possible to suppress the bias of electric charges and prevent burn-in.

  The reverse polarity voltage holding period is appropriately selected according to the length of the writing period, lighting period, and the like. Usually, the reverse polarity voltage holding period is set in the order of ms, and can be set to, for example, 1 ms to 5 ms.

  In the present invention, in one area, the non-selection period is from the end of the last subframe erasure period to the start of the next frame in the previous frame. Since the light source is not turned on during this non-selection period, basically, no matter how the liquid crystal is driven, the image display is not affected. In this non-selection period, a reverse polarity voltage holding period that can prevent burn-in can be provided.

8). Alternating voltage application period In the driving method of the liquid crystal display device of the present invention, a plurality of switching elements are simultaneously applied by simultaneously applying voltages to a plurality of gate lines in one region after the erasing period of the last subframe in one frame. A first holding period in which a voltage having a first polarity is simultaneously applied to a plurality of source lines and held; and a plurality of switching elements are applied by simultaneously applying a voltage to a plurality of gate lines in the one region. You may have the alternating voltage application period which turns on simultaneously and has alternately the 2nd holding | maintenance period which applies and hold | maintains the voltage of 2nd polarity simultaneously to several source lines. This alternating voltage application period is provided only once in one frame. In the case where the reverse polarity holding period is provided, the alternating voltage application period is not provided.

  FIG. 10 is a timing chart showing an example of a method for driving a liquid crystal display device by a field sequential method using the circuit diagram shown in FIG. As the liquid crystal, a ferroelectric liquid crystal in which liquid crystal molecules operate only when a positive voltage is applied as illustrated in FIG. 3B is used. Further, the symbols in FIG. 10 are the same as the symbols in FIG.

First, in the first set of regions _{A 1,} in subframe SF _R frame _{F 1,} the gate lines _G 1 m _rows, G 2, ... and a voltage from the m-th row in the order of the first row is applied to _{G m} The plurality of switching elements 4 are sequentially turned on in units of gate lines, and a positive voltage is applied to the _k source lines S ₁ , S ₂ ,... S _k , and the liquid crystal is supplied via the switching elements 4 and the pixel electrodes 5. A positive voltage is applied to the liquid crystal to drive the liquid crystal (writing period T _a ). Next, after the writing period Ta, _a liquid crystal response period _Tb is provided as a liquid crystal response time (rise time). Then, after the liquid crystal is driven at a pixel along the last gate line G _1, by irradiating predetermined time the red light R from the red light source, so that the red image is recognized (lighting period T _c). Then, the gate lines _{G 1,} G 2 of the m rows, ... with simultaneously on a plurality of the switching elements 4 and simultaneously applying a voltage to the _{G m,} the source lines _S 1 of k _columns, S 2, ... _{S k} simultaneously A negative voltage is applied to reset the driving state of the liquid crystal (erasing period T _d ).

Then, in the sub-frame SF _G, writing scanning the gate lines from the first row in reverse order of the m-th row to the scan order in the sub-frame SF _R, the liquid crystal responds as the sub-frame SF _R, Turn on and erase. Then, in the sub-frame SF _B, similarly to the sub-frame SF _R, the writing scanning the gate lines from the m-th row in the order of the first row, perform liquid crystal response, lighting and erasing.

Next, a negative voltage is applied to _k source lines S ₁ , S ₂ ,... S _k (second holding period T ₂ ), and m rows of gate lines G ₁ , G _{2 ,.} Are simultaneously turned on to simultaneously turn on the plurality of switching elements 4 and simultaneously apply and hold a positive voltage to the _k- line source lines S ₁ , S ₂ ,... S _k (first holding period T ₁ ) Further, a plurality of switching elements 4 are simultaneously turned on by simultaneously applying voltages to m rows of gate lines G ₁ , G ₂ ,... G _m , and k columns of source lines S ₁ , S _{2 ,.} At the same time, a negative voltage is applied and held (second holding period T ₂ ). This is the alternating voltage application period _Tf .
At this time, in addition to lighting period _{T c} of the area _{A 2} that is adjacent to the area _{A 1,} providing the first holding period _{T 1.} That is, providing the first holding period T ₁ during the period when the light source in adjacent regions A ₂ is not illuminated.
Further, data different from the data written in the writing period is written in the alternating voltage application period.

Further, in the first set of regions _{A 2,} shifted by writing period _{T a} portion of the sub-frame SF _R regions _{A 1,} in the same manner as area _{A 1,} the writing, the liquid crystal response, lighting, erase, write, liquid crystal response , Lighting, erasing, writing, liquid crystal response, lighting, and erasing. Then, in addition to lighting period T _c of the region A ₁ and A ₃ adjacent the regions A _2, i.e. the period during which the light source is not illuminated at adjacent regions A ₁ and A _3, providing the first holding period T ₁ . At this time, data different from the data written in the writing period is written in the alternating voltage application period.

In the second set of regions _{A 3,} shifted by the amount of combined writing period _{T a} region _{A 2} of the sub-frame SF _R and the sub-frame SF _G and the sub-frame SF _B, a first set of regions _{A 1} and Similarly, writing, liquid crystal response, lighting, erasing, writing, liquid crystal response, lighting, erasing, writing, liquid crystal response, lighting, and erasing are performed. Then, in addition to lighting period T _c of the region A ₂ and A ₄ is adjacent to the region A _3, that is, the period in which the light source is not illuminated at adjacent regions A ₂ and A _4, providing the first holding period T ₁ . At this time, data different from the data written in the writing period is written in the alternating voltage application period.
Further, in the second set of regions _{A 4,} shifted by writing period _{T a} portion of the sub-frame SF _R region _{A 3,} in the same manner as the first set of regions _{A 1,} write, liquid crystal response, lighting, erase, Writing, liquid crystal response, lighting, erasing, writing, liquid crystal response, lighting, and erasing are performed. Then, in addition to lighting period T _c of the area A ₃ adjacent to the region A _4, that is, the period in which the light source in adjacent areas A ₃ is not lit, providing the first holding period T _1. At this time, data different from the data written in the writing period is written in the alternating voltage application period.

Next, the first set of regions A _1, in subframe SF _R of the next frame F _2, the order of the m-th row from the first row write scan the gate lines, a liquid crystal responds as described above, the lighting and Erase. Then, although not shown, in the next frame F ₂ of the sub-frame SF _G, writing scanning the gate lines from the m-th row in the order of the first row, in the same manner as described above the liquid crystal response, it performs on and erased. Then, in the next frame F ₂ of the sub-frame SF _B, writing by scanning the gate lines in the order of the m-th row from the first row, in the same manner as described above the liquid crystal response, it performs on and erased. Then, as in the previous frame F _1, performs alternating voltage applied.

  In one area, a series of driving (writing, liquid crystal response, lighting, erasing, writing, liquid crystal response, lighting, erasing, writing, liquid crystal response, lighting, erasing, and alternating voltage application) is written for each subframe. The scanning order in the period is reversed, and the process is repeated while changing the color RGB of the light emitted from the light source and the image to be displayed. In one set of areas, image data is written for each color. Then, in 2n areas, image data is written in three colors of RGB for each set. By repeating such a series of driving operations, images of different colors can be visually mixed and recognized as a full color image.

The timing chart of the region _{A 1} shown in FIG. 10 is shown in FIG. 11. The symbols in FIG. 11 are the same as the symbols in FIG.

First, in the sub-frame SF _R, by applying a voltage sequentially to the plurality of gate lines as well as on the plurality of switching elements in order in the gate line basis, by applying a voltage of positive polarity (+) to a plurality of source lines, The liquid crystal is driven by applying a positive (+) voltage to the liquid crystal through the switching element and the pixel electrode (writing period T _a ). Next, after the writing period Ta, _a liquid crystal response period _Tb is provided as a liquid crystal response time (rise time). Next, after the liquid crystal in the pixels along the last gate line is driven, red light R is emitted from the red light source for a certain period of time so that a red image is recognized (lighting period T _c ). Next, a voltage is simultaneously applied to the plurality of gate lines to simultaneously turn on the plurality of switching elements, and a negative (−) voltage is simultaneously applied to the plurality of source lines to reset the driving state of the liquid crystal (erase) Period T _d ).
Then, in the sub-frame SF _G, writing scanning the gate lines from the first row in reverse order of the m-th row to the scan order in the sub-frame SF _R, the liquid crystal responds as the sub-frame SF _R, Turn on and erase. Then, in the sub-frame SF _B, similarly to the sub-frame SF _R, the writing scanning the gate lines from the m-th row in the order of the first row, perform liquid crystal response, lighting and erasing.
Next, a negative polarity to the plurality of source lines (-) voltage is kept applied to the (second holding period T _2), a plurality of gate lines G _1, G 2, _... simultaneously applying a voltage to G _m A plurality of switching elements 4 are simultaneously turned on, a positive voltage is simultaneously applied to a plurality of source lines S ₁ , S ₂ ,... S _k and held (first holding period T ₁ ), and a plurality of gate lines G _{1, G} 2, _... simultaneously applying a voltage to the G _m as well as on the plurality of switching elements 4 at the same time, a plurality of source lines S _1, S 2, _... by applying a negative voltage at the same time S _k Hold (second holding period T ₂ ). This is the alternating voltage application period _Tf .

  In this way, in one frame, after the erasing period of the last subframe, there is an alternating voltage application period only once, and in this alternating voltage application period, the liquid crystal in each pixel is positive and negative. Since the voltage is alternately applied and held, when a still image is displayed for a long time, it is possible to suppress the bias of electric charge and prevent burn-in. In particular, since the data written in the alternating voltage application period is different from the data written in the writing period, it is possible to effectively suppress the charge bias.

In the alternating voltage application period, data different from the data written in the writing period is written. Thereby, the bias of electric charges can be effectively suppressed.
Note that the data written in the alternating voltage application period is different from the data written in the writing period that the data written in the alternating voltage application period has nothing to do with the image data written in the writing period. Say. Since burn-in occurs when a fixed image is displayed for a long time, data unrelated to image data is written in an alternating voltage application period. At this time, a different voltage is applied to each source line. The data to be written in the alternating voltage application period is preferably data that does not partially bias the density of the image.

The second holding period is a period in which voltages are simultaneously applied to a plurality of gate lines to simultaneously turn on a plurality of switching elements and a voltage having a second polarity is simultaneously applied to a plurality of source lines to be held. As illustrated in FIG. 11, a voltage of the second polarity (negative polarity in FIG. 11) is applied in the erasing period _Td , and then the voltage of the second polarity (as illustrated in the alternating voltage application period _Tf ). 11 is negative), the first second holding period of the alternating voltage application period is a period for holding the voltage of the second polarity applied in the erasing period as it is.

In the first holding period, the first polarity voltage is applied and held, and in the second holding period, the second polarity voltage is applied and held. In the present invention, the polarity of the voltage applied in the writing period is the first polarity. Therefore, for example, as shown in FIG. 11, when _a positive voltage is applied in the writing period Ta, the first polarity is positive and the second polarity is negative. On the other hand, although not shown, when a negative voltage is applied during the writing period, the first polarity is negative and the second polarity is positive.

  The alternating voltage application period only needs to have the first holding period and the second holding period alternately, and the order and number of times of the first holding period and the second holding period are not particularly limited.

As an order of the first holding period and the second holding period, as illustrated in FIG. 11, the alternating voltage application period T _f may start from the second holding period T ₂ . You may start with a retention period. In particular, it is preferable that the alternating voltage application period starts from the second holding period. This is because the voltage of the first polarity is applied in the writing period, and therefore it is preferable to apply the voltage of the second polarity first in the alternating voltage application period in order to prevent the bias of the charge.
As the order of the first retention period and a second holding period may be alternating voltage application period T _f as illustrated in FIG. 11 terminates in a second holding period T _2, but not shown alternating voltage application period The first holding period may end.

  Moreover, as the number of times of the first holding period and the second holding period, the first holding period and the second holding period need only be alternately provided, so the total number of the first holding period and the second holding period is 2 The number of times of the first holding period and the second holding period may be one or more times. The total number of times of the first holding period and the second holding period may be two or more as described above, but is usually about 2 to 4 times. Further, the number of times of the first holding period may be one or more, but is usually about once or twice. The number of times of the second holding period may be one or more, but is usually about once or twice.

  The alternating voltage application period is appropriately selected according to the length of the writing period, lighting period, and the like. Usually, the alternating voltage application period is set on the order of ms, and can be set to, for example, 1 ms to 3 ms.

Further, the lengths of the first holding period and the second holding period are not particularly limited, but the length of all the second holding periods is longer than the length of all the first holding periods. It is preferable that the length is longer. Since the voltage of the first polarity is applied during the writing period, the second holding period in which the voltage of the second polarity opposite to the first polarity is applied and held is held in order to prevent the bias of charge. This is because the combined length is preferably relatively long. Note that even when the total length of all the second holding periods is relatively short, by increasing the magnitude of the applied voltage, it is possible to suppress the bias of electric charges and prevent burn-in.
The length of one first holding period and the length of one second holding period are appropriately selected according to the length of the alternating voltage application period, and are usually set to about 500 μs to 1000 μs.

  In addition, the first holding period of a certain area is provided other than the lighting period of the area adjacent to the area. That is, the first holding period is provided in a period in which the light source is not lit in the adjacent region. This is because if the first holding period is provided in the lighting period in which the light source is lit in the adjacent area, light may leak from the adjacent area.

  Furthermore, it is preferable that the data to be written in the alternating voltage application period is randomly different for each frame. This is because the bias of charge can be further suppressed.

  In the present invention, as described above, in one area, the non-selection period is from the end of the erasing period of the last subframe in the previous frame until the start of the next frame. Since the light source is not turned on during this non-selection period, basically, no matter how the liquid crystal is driven, the image display is not affected. An alternating voltage application period that can prevent burn-in can be provided in this non-selection period.

9. Third Initialization Period In the driving method of the liquid crystal display device of the present invention, after the reverse polarity voltage holding period or the alternating voltage application period, a plurality of switching elements are provided by simultaneously applying a voltage to a plurality of gate lines in one region. You may have the 3rd initialization period which applies a zero voltage simultaneously to a several source line while turning on simultaneously.
For example, when a zero voltage is applied in the erasing period, a third initialization period is provided after the reverse polarity voltage holding period or the alternating voltage application period, so that the immediately preceding reverse polarity voltage holding period or the alternating voltage application period is provided. This is because the operation start positions of the liquid crystals can be aligned. In particular, it is possible to align the liquid crystal operation start positions immediately before the writing period of each subframe.
Further, for example, in the case where the second polarity voltage is applied in the erasing period, the third initialization period is provided after the reverse polarity voltage holding period or the alternating voltage application period, so that the first subframe writing period is set. This is because the response speed (rise) of the liquid crystal can be increased, and the response time of the liquid crystal (liquid crystal response period) can be shortened.

  In addition, when the second polarity voltage is applied in the erasing period, the third polarity is applied not only after the reverse polarity voltage holding period or the alternating voltage application period but also after the erasing period of a subframe other than the last subframe. An initialization period may be provided. This is because the response speed (rise) of the liquid crystal can be increased and the response time of the liquid crystal (liquid crystal response period) can be shortened in the writing period of each subframe. Further, by providing the third initialization period after the reverse polarity voltage holding period or the alternating voltage application period and after the erasing period of the subframes other than the last subframe, the liquid crystal operation immediately before the writing period of each subframe is performed. This is because the start positions can be aligned.

  When the third initialization period is provided after the reverse polarity voltage holding period or the alternating voltage application period, the third initialization period is provided immediately after the reverse polarity voltage holding period or the alternating voltage application period and immediately before the next frame. It is done. Further, when the third initialization period is provided after the erasing period of the subframes other than the last subframe, the third initialization period is performed immediately after the erasing period of the subframes other than the last subframe. It is provided immediately before.

  When the third initialization period is provided after the reverse polarity voltage holding period or the alternating voltage application period, either the reverse polarity voltage holding period or the alternating voltage application period and the third initialization period may be longer or shorter. . For example, when the scanning order in the writing period of the previous subframe and the scanning order in the writing period of the next subframe are the same, the reverse polarity voltage holding period or the alternating voltage application period is the third initialization period. Longer and relatively longer. In this case, since the same polarity voltage is applied for a relatively long time in a line with a fast scanning order compared to a line with a slow scanning order, the reverse polarity voltage holding period or the alternating voltage application period is relatively long. This is because it is preferable. On the other hand, for example, when the scanning order in the writing period of the previous subframe and the scanning order in the writing period of the next subframe are reversed, the reverse polarity voltage holding period or the alternating voltage application period is the third initial period. It may be longer or shorter than the conversion period. In this case, since the time during which the voltage is applied is averaged between the line with the earlier scanning order and the line with the later scanning order, the reverse polarity voltage holding period or the alternating voltage application period may be relatively short. .

  Further, in the case where the second polarity voltage is applied in the erasing period, the third initialization period is provided after the reverse polarity voltage holding period or the alternating voltage application period, and the subframes other than the last subframe are provided. When the third initialization period is longer than the reverse polarity voltage holding period or the alternating voltage application period, a plurality of gate lines are simultaneously applied with a voltage immediately before the next frame. These switching elements may be simultaneously turned on, and a second polarity voltage may be simultaneously applied to a plurality of source lines. This makes it possible to align the liquid crystal operation start positions immediately before the writing period of each subframe.

  The third initialization period is usually set on the order of μs or ms.

  When the third initialization period is provided after the erasing period of subframes other than the last subframe, the third initialization period can be set to 6 μs to 8 μs, for example. Further, when the third initialization period is provided after the reverse polarity voltage holding period or the alternating voltage application period and the third initialization period is shorter than the reverse polarity voltage holding period or the alternating voltage application period, The third initialization period can be set at, for example, 6 μs to 8 μs.

  Further, when the third initialization period is provided after the reverse polarity voltage holding period or the alternating voltage application period, and when using a liquid crystal having spontaneous polarization, for example, a ferroelectric liquid crystal, the third initialization period, The time for applying the zero voltage simultaneously to the plurality of gate lines is preferably longer than the time required for the response of the liquid crystal, and more preferably about the time required for the response of the liquid crystal. In the third initialization period, the time for applying the zero voltage simultaneously to the plurality of gate lines is made longer than the time required for the response of the liquid crystal, so that the liquid crystal operates and the direction of the spontaneous polarization is reversed. Since the charge for compensating for the reduced charge due to the polarization of is supplied, the charge amount can be equalized in all the pixels. As a result, it is possible to prevent the liquid crystal response from being lowered.

  In the third initialization period, when the time for applying the voltage simultaneously to the plurality of gate lines is set to the time required for the liquid crystal response, the time for applying the zero voltage to the plurality of gate lines simultaneously is, for example, 100 μs. It can be set at ˜500 μs.

10. Other Periods In the present invention, as illustrated in FIG. 12, a subframe SF _W that displays white may be provided.
In the example shown in FIG. 12, after writing the three primary colors of RGB for each group in all areas A _{1 to} A ₄ , the RGB three-color light sources are simultaneously turned on to obtain white light, and all areas A ₁ It is written order for white in to a _4. In the subframe SF _W , similarly to the subframes SF _R , SF _G , and SF _B , a writing period T _a ′, a liquid crystal response period T _b ′, a lighting period T _c ′, and an erasing period T _d ′ are provided. Yes.

  When displaying white, the white image data is the smallest signal among the original RGB image data, and the RGB image data is converted from the original RGB signal to the white signal. The signal value can be subtracted. For example, when the original RGB image data is (R, G, B) = (125, 100, 220), the minimum signal 100 is a white signal, and 100 is subtracted from the original RGB signal Can be (R, G, B, W) = (25, 0, 120, 100).

  Since a color break does not occur in the white display, the writing of the white image data can be started after the writing of RGB for each group is completed in all regions. When white is displayed, W may be written after the writing of RGB is completed for each group in all areas as described above, or RGBW may be written for each group in all areas.

11. Liquid crystal The liquid crystal used in the present invention is not particularly limited as long as it has high-speed response. Examples of the liquid crystal having high-speed response include a ferroelectric liquid crystal and an OCB mode liquid crystal.

Among these, ferroelectric liquid crystal is preferably used. This is because the ferroelectric liquid crystal has spontaneous polarization, so that the response speed is extremely short on the order of μs and is suitable for a high-speed device.
Hereinafter, the ferroelectric liquid crystal will be described.

The ferroelectric liquid crystal used in the present invention is not particularly limited as long as it exhibits a chiral smectic C phase (SmC ^* ). For example, the phase sequence changes in phase with the nematic phase (N) -cholesteric phase (Ch) -chiral smectic C phase (SmC ^* ) in the temperature lowering process, the nematic phase (N) -chiral smectic C phase (SmC ^* ) , Nematic phase (N) -smectic A phase (SmA) -chiral smectic C phase (SmC ^* ), phase change, nematic phase (N) -cholesteric phase (Ch) -smectic A phase (SmA ) -Chiral smectic C phase (SmC ^* ) and the like.

Among these, it is preferable that the ferroelectric liquid crystal is monostable.
“Showing monostability” means a state in which the state of the ferroelectric liquid crystal when no voltage is applied is stabilized in one state. In the ferroelectric liquid crystal, as illustrated in FIG. 13, the liquid crystal molecules 1 are tilted from the layer normal z and rotate along a cone ridge having a bottom surface perpendicular to the layer normal z. In such a cone, the tilt angle of the liquid crystal molecules 1 with respect to the layer normal z is referred to as a tilt angle θ. Thus, the liquid crystal molecules 1 can operate on the cone between two states inclined by a tilt angle ± θ with respect to the layer normal z. Specifically, showing monostability means a state where the liquid crystal molecules 1 are stabilized in any one state on the cone when no voltage is applied.

  The ferroelectric liquid crystal exhibiting monostability has a V shaped switching characteristic in which liquid crystal molecules operate when a positive or negative voltage as illustrated in FIG. 14 is applied. And those showing half-V shaped switching characteristics in which liquid crystal molecules operate only when a positive or negative voltage as illustrated in FIG. 3 is applied. Either can be used.

In particular, a ferroelectric liquid crystal exhibiting half V-shaped switching characteristics is preferably used. Using a ferroelectric liquid crystal exhibiting such a half V-shaped switching characteristic, it is possible to take a sufficiently long opening time as a black and white shutter, thereby making it possible to display each color that is temporally switched brighter. A liquid crystal display device with bright color display can be realized.
The “half V-shaped switching characteristic” refers to an electro-optical characteristic in which the light transmittance with respect to an applied voltage is asymmetric.

  Such a ferroelectric liquid crystal can be variously selected from generally known liquid crystal materials according to required characteristics.

In particular, a liquid crystal material that exhibits an SmC ^* phase from the Ch phase without passing through the SmA phase is suitable as a material that exhibits a half V-shaped switching characteristic. Specifically, “R2301” manufactured by AZ Electronic Materials may be mentioned.

In addition, as the liquid crystal material that passes through the SmA phase, a material that expresses the SmC ^* phase from the Ch phase through the SmA phase is preferable because of a wide range of material selection. In this case, a single liquid crystal material exhibiting an SmC ^* phase can be used, but a non-chiral liquid crystal (hereinafter sometimes referred to as a host liquid crystal) having a low viscosity and easily exhibiting an SmC phase is used. By adding a small amount of an optically active substance that does not show large spontaneous polarization and an appropriate helical pitch, the liquid crystal material showing the phase sequence as described above has low viscosity and can realize faster response. preferable.

The host liquid crystal is preferably a material exhibiting an SmC phase in a wide temperature range, and can be used without particular limitation as long as it is generally known as a host liquid crystal of a ferroelectric liquid crystal. For example, the general formula:
^{Ra-Q 1 -X 1 - (} Q 2 -Y 1) m -Q 3 -Rb
(In the formula, Ra and Rb are each a linear or branched alkyl group, alkoxy group, alkoxycarbonyl group, alkanoyloxy group or alkoxycarbonyloxy group, and Q ¹ , Q ² and Q ³ are each 1 , 4-phenylene group, 1,4-cyclohexylene group, pyridine-2,5-diyl group, pyrazine-2,5-diyl group, pyridazine-3,6-diyl group, 1,3-dioxane-2,5 -Diyl group, and these groups may have a substituent such as a halogen atom, a hydroxyl group, and a cyano group, and X ¹ and Y ¹ are each —COO—, —OCO—, —CH ₂ O— , —OCH ₂ —, —CH ₂ CH ₂ —, —C≡C—, or a single bond, and m is 0 or 1.). As the host liquid crystal, the above compounds can be used alone or in combination of two or more.

The optically active substance added to the host liquid crystal is not particularly limited as long as it is a material having a large spontaneous polarization and the ability to induce an appropriate helical pitch, and is generally added to a liquid crystal composition exhibiting an SmC phase. Any known material can be used. In particular, a material that can induce large spontaneous polarization with a small addition amount is preferable. Examples of such an optically active substance include the following general formula:
^{Rc-Q 1 -Za-Q 2} -Zb-Q 3 -Zc-Rd
(In the formula, Q ¹ , Q ² and Q ³ represent the same meaning as in the above general formula, and Za, Zb and Zc are —COO—, —OCO—, —CH ₂ O—, —OCH ₂ —, —CH _{2, respectively.} CH ₂ —, —C≡C—, —CH═N—, —N═N—, —N (→ O) ═N—, —C (═O) S— or a single bond, and Rc is asymmetric. A linear or branched alkyl group which may have a carbon atom, an alkoxy group, an alkoxycarbonyl group, an alkanoyloxy group or an alkoxycarbonyloxy group, wherein Rd is a linear or branched group having an asymmetric carbon atom; And an alkyl group, an alkoxy group, an alkoxycarbonyl group, an alkanoyloxy group or an alkoxycarbonyloxy group, and Rc and Rd may be substituted with a halogen atom, a cyano group or a hydroxyl group. Can be used. As the optically active substance, the above compounds may be used alone or in combination of two or more.

  Specific examples of the ferroelectric liquid crystal passing through the SmA phase include “FELIXM4851-100” manufactured by AZ Electronic Materials.

  A compound having an arbitrary function may be added to the ferroelectric liquid crystal depending on the function required for the liquid crystal display device. Examples of such a compound include a polymerized polymerizable monomer. By containing a polymer of such a polymerizable monomer in the liquid crystal layer, the alignment of the liquid crystal material is so-called “polymer stabilization”, and a liquid crystal display device excellent in alignment stability can be obtained.

  The polymerizable monomer used in the polymerized polymer of the polymerizable monomer is not particularly limited as long as it is a compound that generates a polymer by a polymerization reaction, and a thermosetting resin monomer that generates a polymerization reaction by heat treatment, and actinic radiation. An actinic radiation curable resin monomer that undergoes a polymerization reaction upon irradiation of can be exemplified. Among these, it is preferable to use an actinic radiation curable resin monomer. When a thermosetting resin monomer is used, it is necessary to perform a heating process in order to cause a polymerization reaction. Therefore, the regular arrangement of the ferroelectric liquid crystal is impaired by such a heating process, There is a risk of inducing a phase transition. On the other hand, when the actinic radiation curable resin monomer is used, there is no such fear, and the alignment of the ferroelectric liquid crystal is hardly harmed by the polymerization reaction.

  Examples of the actinic radiation curable resin monomer include an electron beam curable resin monomer that undergoes a polymerization reaction upon irradiation with an electron beam, and a photocurable resin monomer that undergoes a polymerization reaction upon irradiation with light. Among these, it is preferable to use a photocurable resin monomer. It is because a manufacturing process can be simplified by using a photocurable resin monomer.

  The photocurable resin monomer is not particularly limited as long as it causes a polymerization reaction when irradiated with light having a wavelength in the range of 150 nm to 500 nm. Among them, it is preferable to use an ultraviolet curable resin monomer that generates a polymerization reaction when irradiated with light having a wavelength in the range of 250 nm to 450 nm, particularly in the range of 300 nm to 400 nm. This is because it has advantages in terms of the ease of the irradiation apparatus.

  The polymerizable functional group possessed by the ultraviolet curable resin monomer is not particularly limited as long as it causes a polymerization reaction upon irradiation with ultraviolet rays in the above wavelength region. In particular, it is preferable to use an ultraviolet curable resin monomer having an acrylate group.

  Further, the UV curable resin monomer may be a monofunctional monomer having one polymerizable functional group in one molecule, or a polyfunctional having two or more polymerizable functional groups in one molecule. It may be a monomer. Among these, it is preferable to use a polyfunctional monomer. By using a polyfunctional monomer, a stronger polymer network can be formed, so that the intermolecular force and the polymer network at the alignment film interface can be strengthened. Thereby, the disorder of the alignment of the ferroelectric liquid crystal due to the temperature change can be suppressed.

  Among the polyfunctional monomers, bifunctional monomers having a polymerizable functional group at both ends of the molecule are preferably used. By having a polymerizable functional group at both ends of the molecule, it is possible to form a polymer network with a wide interval between polymers, and to prevent a decrease in driving voltage of the ferroelectric liquid crystal due to the inclusion of a polymer of a polymerizable monomer. Because.

  Of the ultraviolet curable resin monomers, it is preferable to use an ultraviolet curable liquid crystal monomer that exhibits liquid crystallinity. The reason why such an ultraviolet curable liquid crystal monomer is preferable is as follows. That is, since the ultraviolet curable liquid crystal monomer exhibits liquid crystallinity, it can be regularly arranged by the alignment regulating force of the alignment film. For this reason, the ultraviolet curable liquid crystal monomer can be fixed while maintaining the regular alignment state by causing a polymerization reaction after the ultraviolet light curable liquid crystal monomer is regularly arranged. By the presence of the polymer having such a regular alignment state, the alignment stability of the ferroelectric liquid crystal can be improved, and excellent heat resistance and impact resistance can be obtained.

  The liquid crystal phase exhibited by the ultraviolet curable liquid crystal monomer is not particularly limited, and examples thereof include an N phase, an SmA phase, and an SmC phase.

  Examples of the ultraviolet curable liquid crystal monomer used in the present invention include compounds represented by the following formulas (1) to (3).

In the above formulas (1) and (2), A, B, D, E and F represent benzene, cyclohexane or pyrimidine, and these may have a substituent such as halogen. A and B, or D and E may be bonded via a bonding group such as an acetylene group, a methylene group, or an ester group. M ¹ and M ² may be any of a hydrogen atom, an alkyl group having 3 to 9 carbon atoms, an alkoxycarbonyl group having 3 to 9 carbon atoms, or a cyano group. Further, the acryloyloxy group at the end of the molecular chain and A or D may be bonded via a bonding group such as an alkylene group having 3 to 6 carbon atoms.

  In the above formula (3), Y is hydrogen, alkyl having 1 to 20 carbons, alkenyl having 1 to 20 carbons, alkyloxy having 1 to 20 carbons, alkyloxycarbonyl having 1 to 20 carbons, It represents formyl, alkylcarbonyl having 1 to 20 carbons, alkylcarbonyloxy having 1 to 20 carbons, halogen, cyano or nitro.

  Among the above, the compounds represented by the following formulas can be exemplified as those suitably used.

  Moreover, the said polymerizable monomer may be used independently and may be used in combination of 2 or more type. When two or more different polymerizable monomers are used, for example, an ultraviolet curable liquid crystal monomer represented by the above formula and another ultraviolet curable resin monomer can be used.

  When an ultraviolet curable liquid crystal monomer is used as the polymerizable monomer, the polymer of the polymerizable monomer is a main chain liquid crystal type polymer in which the main chain exhibits liquid crystallinity by having an atomic group exhibiting liquid crystallinity in the main chain. It may be a side chain liquid crystal polymer in which the side chain exhibits liquid crystallinity by having an atomic group exhibiting liquid crystallinity in the side chain. Especially, it is preferable that the polymer of a polymerizable monomer is a side chain liquid crystal type polymer. This is because the presence of an atomic group exhibiting liquid crystallinity in the side chain increases the degree of freedom of the atomic group, so that the atomic group exhibiting liquid crystallinity is easily aligned. Further, as a result, the alignment stability of the ferroelectric liquid crystal can be improved.

The amount of the polymerized monomer in the liquid crystal layer is not particularly limited as long as the alignment stability of the ferroelectric liquid crystal is within a desired range, but usually 0.5% by mass in the liquid crystal layer. It is preferably within the range of ˜30% by mass, more preferably within the range of 1% by mass to 20% by mass, and even more preferably within the range of 1% by mass to 10% by mass. This is because if it exceeds the above range, the drive voltage may increase or the response speed may decrease. On the other hand, if the amount is less than the above range, the alignment stability of the ferroelectric liquid crystal becomes insufficient, and the heat resistance and impact resistance of the liquid crystal display device may be impaired.
The abundance of the polymerizable monomer polymer in the liquid crystal layer is obtained by washing the monomolecular liquid crystal in the liquid crystal layer with a solvent and then measuring the weight of the remaining polymerizable monomer polymer with an electronic balance. It can be calculated from the remaining amount and the total mass of the liquid crystal layer.

12.2n Regions In the present invention, the region is divided into 2n (n is an integer of 2 to 4) regions having a plurality of continuous gate lines. The number of regions is 2n (n is an integer of 2 to 4), specifically, any of 4, 6, or 8. For example, when j rows of gate lines and k columns of source lines are formed as shown in FIG. 1, four regions (A _{1 to} A ₄ ), six in the row direction as illustrated in FIG. is divided into regions _(a 1 ~A ₆₎ or eight regions _(a 1 ~A _8).

In addition, 2n areas are a set of arbitrary two areas.
The two arbitrary regions are not particularly limited. For example, in the case of the four regions shown in FIG. 15A, A ₁ and A ₂ are the first set, and A ₃ and A ₄ are the second. A ₁ and A ₃ may be a first set, A ₂ and A ₄ may be a second set, A ₁ and A ₄ may be a first set, and A ₂ and A ₃ may be a second set. .
Further, the combination of any two regions may be the same in all frames or may be different for each frame.
As the number of sets, for example, two sets of two in the case of four areas, three sets of two in the case of six areas, and four sets of two in the case of eight areas. Is done.

Also, when the number of gate lines is large as in full high-definition (FHD), the FHD panel is divided into two upper and lower areas, the upper area is the source driver placed on the upper side, and the lower area is placed on the lower side. Data can be input with the source driver. As described above, by arranging the source drivers in both the upper and lower two regions, the gate lines can be scanned in parallel.
FIG. 16 shows a driving method when an FHD panel is taken as an example, in which display is performed symmetrically in the upper region and the lower region. In FIG. 16, the display is performed symmetrically in the upper region and the lower region, but the present invention is not necessarily limited to this mode, and different driving methods may be used for the upper region and the lower region. .
In the example shown in FIG. 16, the upper region is divided into _four regions A _{1 to} A ₄ , and LEDs are arranged in the respective regions. Further, the lower region is divided into four regions A _{5 to} A ₈ , and LEDs are arranged in the respective regions. The LEDs in each area can be controlled ON / OFF independently. In this case, since the lighting timing of the LEDs is the same in the region A ₄ and the region A _5, it is not necessary to consider the influence of light leakage.

The number of gate lines may be plural, but it is preferable that the number of the gate lines be such that the writing period is equal to or longer than the total time of the liquid crystal response period, the lighting period, and the erasing period.
In addition, when dividing a plurality of gate lines into 2n regions, the number of gate lines for one region is not particularly limited, but as described above, the writing period is the liquid crystal response period, the lighting It is preferable that the number is equal to or longer than the total time of the period and the erasing period.

  In the 2n areas, light sources of a plurality of colors are provided for each area.

B. Next, the liquid crystal display device of the present invention will be described.
The liquid crystal display device of the present invention is connected to a plurality of gate lines divided into 2n (n is an integer of 2 to 4) regions, a plurality of source lines, and the gate lines and source lines. A plurality of arranged switching elements, a plurality of pixel electrodes connected to the switching elements and arranged for each pixel, a counter electrode arranged at a position facing the pixel electrode, and between the pixel electrode and the counter electrode A liquid crystal panel including: a liquid crystal disposed in a plurality of gate lines; a gate driver connected to the plurality of gate lines to apply a scanning signal; and a source driver connected to the plurality of source lines to apply an image signal; and A liquid crystal panel that emits light to the liquid crystal panel and is connected to the plurality of color light sources provided for each of the regions, and the gate driver, source driver, and light source, and the liquid crystal display device described above The driving method is characterized in that it has a control unit for driving the liquid crystal display device.

FIG. 17 is a schematic perspective view showing an example of the liquid crystal display device of the present invention.
As illustrated in FIG. 17, the liquid crystal display device 10 includes a liquid crystal panel 11, a light source 12 disposed so as to face the liquid crystal panel 11, a gate driver 2 and a source driver 3 of the liquid crystal panel 11, and a light source 12. And a connected control unit 13. In the liquid crystal panel 11, a plurality of gate lines G and a plurality of source lines S and a plurality of switching elements 4 connected to the gate lines G and the source lines S and arranged for each pixel are formed on the base material 7a. A plurality of pixel electrodes 5 connected to the switching element 4 and arranged for each pixel are provided, and a counter electrode 6 is provided on the base material 7 b so as to face the pixel electrode 5. In the liquid crystal panel 11, a gate driver 2 connected to a plurality of gate lines G and a source driver 3 connected to a plurality of source lines S are provided.
The plurality of gate lines G are divided into _four regions (A _{1 to} A ₄ ) in the row direction as illustrated in FIG. Then, RGB light sources 12R, 12G, and 12B are provided for each region.
Although not shown, liquid crystal is sandwiched between the pixel electrode and the counter electrode.

  The gate line G and the source line S are arranged vertically and horizontally, and by applying a signal to the gate line G and the source line S, the switching element 4 can be operated to drive the liquid crystal. A portion where the gate line G and the source line S intersect is insulated by an insulating layer (not shown), and the scanning signal of the gate line G and the image signal of the source line S can operate independently. A portion surrounded by the gate line G and the source line S is a pixel which is a minimum unit for driving the liquid crystal display device, and at least one switching element 4 and a pixel electrode 5 are formed in each pixel. Then, by sequentially applying a signal voltage to the gate line and the source line, the switching element of each pixel can be operated.

  The gate driver 2 applies a voltage to the gate line G (applies a scanning signal), and the source driver 3 applies a positive or negative voltage to the source line S (applies an image signal). At this time, an image signal corresponding to one unit color among a plurality of unit colors (RGB in FIG. 17) for displaying an arbitrary color by mixing colors is supplied to the source line S. Accordingly, the gate driver 2 sequentially applies voltages to the plurality of gate lines G to turn on the plurality of switching elements 4 in units of gate lines, and the source driver 3 applies positive or negative polarity to the plurality of source lines S. A voltage is applied, and a positive or negative voltage is applied to the liquid crystal via the switching element 4 and the pixel electrode 5 to drive the liquid crystal. That is, a voltage corresponding to the image signal is applied between the pixel electrode and the counter electrode of the pixel along each gate line, and image data is written to each pixel along the gate line, and depending on the degree of response of the liquid crystal to this, The light transmittance of each pixel is controlled.

  Since the liquid crystal display device of the present invention is driven by the above-described driving method of the liquid crystal display device, the intervals between the lighting periods of the plurality of light sources can be shortened, and color breaks can be prevented.

  A general thing can be used for each component of a liquid crystal display device. Since the liquid crystal and the light source are described in detail in the above “A. Driving method of liquid crystal display device”, description thereof is omitted here.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has substantially the same configuration as the technical idea described in the claims of the present invention, and any device that exhibits the same function and effect is the present invention. It is included in the technical scope of the invention.

  The following examples illustrate the present invention in more detail.

[Example 1]
The number of gate lines for full high-definition (FHD): The display method of the upper region in the case where the display of 1080 is divided into two vertically and the respective upper and lower regions are further divided into four (8 divided in total) is shown in FIG. The lower region was driven symmetrically with the upper region.
The number of gate lines in each area is 1080/2/4 = 135. The gate selection time was 10.3 μsec, and the time required for 135 writing scans (writing period T _a ) was 1.39 msec. Further, the liquid crystal response period T _b was set to 0.29 msec, the lighting period T _c was set to 0.80 msec, and the erasing period T _d was set to 0.29 msec.

[Example 2]
The number of gate lines for full high-definition (FHD): The display method of the upper region when the display of 1080 is divided into two vertically and the respective upper and lower regions are further divided into four (8 divided in total) is shown in FIG. The lower region was driven symmetrically with the upper region.
The number of gate lines in each area is 1080/2/4 = 135. The gate selection time was 7.7 μsec, and the time required for 135 writing scans (writing period T _a ) was 1.04 msec. Further, the liquid crystal response period T _b was set to 0.22 msec, the lighting period T _c was set to 0.60 msec, and the erasing period T _d was set to 0.22 msec.

[Example 3]
FIG. 6 shows a driving method of the upper region when the number of gate lines of full high-definition (FHD): 1080 displays is divided into two vertically and the respective upper and lower regions are further divided into four (8 divided in total). The lower region was driven symmetrically with the upper region.
The number of gate lines in each area is 1080/2/4 = 135. The gate selection time was 10.3 μsec, and the time required for 135 writing scans (writing period T _a ) was 1.39 msec. The liquid crystal response period T _b was 0.29 msec, the lighting period T _c was 0.80 msec, the erase period T _d was 0.29 msec, and the first initialization period T _g (gate selection time) was 10.3 μsec.

[Comparative Example 1]
The number of gate lines of full high-definition (FHD): The display method of the upper region in the case where the display of 1080 is divided into two vertically and the respective upper and lower regions are further divided into four (8 divided in total) is shown in FIG. The lower region was driven symmetrically with the upper region.
The number of gate lines in each area is 1080/2/4 = 135. The gate selection time was 10.3 μsec, and the time required for 135 writing scans (writing period T _a ) was 1.39 msec. Further, the liquid crystal response period T _b was set to 0.29 msec, the lighting period T _c was set to 0.80 msec, and the erasing period T _d was set to 0.29 msec.
In this case, since the interval d of the LED lighting period requires about 5.6 msec, a color break becomes a problem.

It is a schematic diagram which shows an example of the circuit diagram of the liquid crystal display device of this invention. 4 is a timing chart illustrating an example of a driving method of the liquid crystal display device of the present invention. It is the graph which showed the change of the transmittance | permeability with respect to the applied voltage of a ferroelectric liquid crystal. It is a timing chart which shows the other example of the drive method of the liquid crystal display device of this invention. It is a timing chart which shows the other example of the drive method of the liquid crystal display device of this invention. It is a timing chart which shows the other example of the drive method of the liquid crystal display device of this invention. It is a timing chart which shows the other example of the drive method of the liquid crystal display device of this invention. It is a timing chart which shows the other example of the drive method of the liquid crystal display device of this invention. It is a timing chart which shows the other example of the drive method of the liquid crystal display device of this invention. It is a timing chart which shows the other example of the drive method of the liquid crystal display device of this invention. It is a timing chart which shows the other example of the drive method of the liquid crystal display device of this invention. It is a timing chart which shows the other example of the drive method of the liquid crystal display device of this invention. It is a schematic diagram which shows the behavior of a liquid crystal molecule. It is the graph which showed the change of the transmittance | permeability with respect to the applied voltage of a ferroelectric liquid crystal. It is a schematic diagram which shows 2n area | regions. It is a timing chart which shows the other example of the drive method of the liquid crystal display device of this invention. It is a schematic perspective view which shows an example of the liquid crystal display device of this invention. 10 is a timing chart showing a driving method of Comparative Example 1;

Explanation of symbols

T _a ... writing period T _b ... liquid crystal response period T _c ... lighting period T _d ... erasing period T _e ... reverse polarity voltage holding period T _f ... alternating voltage application period T _g ... first initialization period T _h ... non-selection period T _i ... second initialization period T _i1 ... reverse polarity voltage initialization period T _i2 ... zero voltage initialization period T ₁ ... first holding period T ₂ ... second holding period

Claims (12)

A method of driving a liquid crystal display device, wherein the liquid crystal display device is divided into 2n (n is an integer of 2 to 4) regions having a plurality of continuous gate lines, and a plurality of color light sources are provided for each region.
During each subframe,
A write period in which a plurality of switching elements are sequentially turned on by sequentially applying a voltage to a plurality of gate lines in the one region, and a voltage having a first polarity is applied to a plurality of source lines;
A liquid crystal response period waiting for the liquid crystal to respond after the writing period;
After the liquid crystal response period, a lighting period for turning on the light source of one color provided in the region;
After the lighting period, a voltage is simultaneously applied to the plurality of gate lines in the region to simultaneously turn on the plurality of switching elements, and the second polarity having the opposite polarity to the first polarity is simultaneously applied to the plurality of source lines. An erasing period for applying either a voltage of zero polarity or zero voltage,
Arbitrary two areas out of the 2n areas are set as one set, and a writing period is alternately provided for each area in each set area, and a plurality of colors are written for each set in the 2n areas. A method for driving a liquid crystal display device, characterized in that periods are provided in order.   The method for driving a liquid crystal display device according to claim 1, wherein the writing period is equal to or longer than a total time of the liquid crystal response period, the lighting period, and the erasing period.   After the writing period of one region, a voltage is simultaneously applied to a plurality of gate lines in a region other than the region to simultaneously turn on the plurality of switching elements, and a zero voltage is simultaneously applied to the plurality of source lines. The method for driving a liquid crystal display device according to claim 1, further comprising a first initialization period. In one frame, after the erasing period of the last subframe, a voltage is simultaneously applied to a plurality of gate lines in the one region to simultaneously turn on the plurality of switching elements and at least simultaneously to the plurality of source lines. Having a second initialization period in which a zero voltage is applied and held;
3. The liquid crystal display device according to claim 1, wherein, in the second initialization period, a time for simultaneously applying a voltage to the plurality of gate lines is longer than a time required for a liquid crystal response. Driving method.   In the second initialization period, the voltage of the second polarity is applied simultaneously to the plurality of source lines while simultaneously applying the voltage to the plurality of gate lines in the one region and simultaneously turning on the plurality of switching elements. A reverse polarity voltage initialization period in which a plurality of switching elements are applied and held, and after the reverse polarity voltage initialization period, the plurality of switching elements are simultaneously turned on by simultaneously applying a voltage to the plurality of gate lines in the one region. 5. The method of driving a liquid crystal display device according to claim 4, further comprising: a zero voltage initialization period in which a zero voltage is simultaneously applied to and held in the plurality of source lines.   In one frame, after the erasing period of the last subframe, a voltage is simultaneously applied to a plurality of gate lines in the one region to simultaneously turn on the plurality of switching elements, and simultaneously to the plurality of source lines. 3. The method of driving a liquid crystal display device according to claim 1, further comprising a reverse polarity voltage holding period for applying and holding a voltage of the second polarity. In one frame, after the erasing period of the last subframe, a voltage is simultaneously applied to a plurality of gate lines in the one region to simultaneously turn on the plurality of switching elements, and simultaneously to the plurality of source lines. A first holding period in which a voltage having a first polarity is applied and held; simultaneously applying voltages to the plurality of gate lines in the region to simultaneously turn on the plurality of switching elements; and simultaneously applying to the plurality of source lines Having an alternating voltage application period alternately having a second holding period for applying and holding the voltage of the second polarity;
A first holding period of a certain area is provided in addition to the lighting period of the area adjacent to the area,
The method for driving a liquid crystal display device according to claim 1, wherein data written in the writing period and data written in the alternating voltage application period are different.   8. The method of driving a liquid crystal display device according to claim 7, wherein data to be written in the alternating voltage application period is randomly different for each frame.   9. The scanning order in the writing period of the previous subframe and the scanning order in the writing period of the next subframe are opposite to each other. A driving method of a liquid crystal display device.   When the writing period of a certain region overlaps with the lighting period of a region adjacent to the region, a region adjacent to the region is provided in the writing period of the certain region. 9. The method of driving a liquid crystal display device according to claim 1, wherein scanning is performed from the gate line located on the side opposite to the side where the liquid crystal is present.   11. The method for driving a liquid crystal display device according to claim 1, wherein ferroelectric liquid crystal exhibiting monostable and half V-shaped switching characteristics is used.   A plurality of gate lines divided into 2n (n is an integer of 2 to 4) regions, a plurality of source lines, and a plurality of switching elements connected to the gate lines and the source lines and arranged for each pixel; A plurality of pixel electrodes connected to the switching element and disposed for each pixel; a counter electrode disposed at a position facing the pixel electrode; a liquid crystal disposed between the pixel electrode and the counter electrode; A liquid crystal panel having a gate driver connected to a plurality of gate lines and applying a scanning signal, and a source driver connected to the plurality of source lines and applying an image signal, and irradiating the liquid crystal panel with light And a light source of a plurality of colors provided for each region, and the gate driver, the source driver, and the light source, and connected to any one of claims 1 to 11. The liquid crystal display device characterized by having a control unit for driving the liquid crystal display device by a driving method of a liquid crystal display device.

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