JP2006243422A - Liquid crystal display device and method of driving liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide technique for reducing a blur of a moving picture occurring on a liquid crystal display device. <P>SOLUTION: One frame period is divided into a plurality of sub frame periods and respective rows of liquid crystal pixels are repeatedly selected in order for each sub frame period. In a specific sub frame period including one of the starting sub frame period and ending sub frame period, preset specific image data are outputted as driving image data and in other sub frame periods, image data based upon an input image signal are outputted as driving image data. To liquid crystal pixels in respective columns of respective rows selected one after another, a specific pixel voltage corresponding to the specific image data in the specific sub frame period is applied and a pixel voltage corresponding to the image data based upon the input image signal in other sub frame periods is applied. The specific pixel voltage has a level equal to below a minimum value that the pixel voltage corresponding to the image data based upon the input image signal can has. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a technique for improving blurring of a moving image that occurs when a moving image is displayed on a liquid crystal display device.

  An image display device (also referred to as “liquid crystal display device”) using a liquid crystal panel (also referred to as “liquid crystal device”) is becoming widespread. However, when a moving image is displayed on the liquid crystal display device, there is a problem that the outline or ghost of the contour of the object occurs according to the moving speed of the object in the moving image. Hereinafter, the blur and ghost of the outline of these objects are collectively referred to as “moving image blur”.

  The occurrence of blurring of the moving image as described above is considered to be mainly caused by the following two problems.

  First, a voltage (electric field) corresponding to image data (gradation data) applied to each pixel (hereinafter referred to as “liquid crystal pixel”) of the liquid crystal panel is applied to the pixel. The response speed until the desired light transmittance is reached is low. For example, since the response time of a twisted nematic liquid crystal (hereinafter referred to as “TN type”), which is one of typical liquid crystals, is usually several ms or more for a frame period of about 16.7 ms. In some cases, the change in the light transmittance of each liquid crystal pixel cannot sufficiently follow the change in the applied voltage, resulting in blurring of the moving image.

  Second, each liquid crystal pixel is a hold type electro-optical element. For this reason, the characteristic of the signal frequency represented by the image data given to each liquid crystal pixel has a low-pass type time-frequency characteristic in which the response characteristic in the high frequency is reduced, and accordingly, the displayed display image is visually recognized. As a result, the moving image may be blurred.

  Thus, with respect to the first problem, for example, the technique described in Patent Document 1, Patent Document 2, Patent Document 3, and the like is used to improve the problem. Moreover, about the 2nd problem, improvement of a problem is achieved by using the technique described in patent document 4, patent document 5, etc., for example.

Japanese Patent Laid-Open No. 9-265073 Japanese Patent No. 1-10299 Japanese Patent No. 2002-207463 JP 2001-296838 A Japanese Patent Laid-Open No. 2001-311932

  However, the conventional technique used for improving the first problem described above has the problems described below.

  The technique described in Patent Document 1 increases the response speed of the liquid crystal by applying the repetitive voltage to the liquid crystal many times, and therefore applies the repetitive voltage to the liquid crystal many times. Therefore, there is a problem that a complicated circuit is required. Another problem is that the processing speed of the circuit must be increased in accordance with the increase in display resolution.

  Further, the technique described in Patent Document 2 is obtained based on gradation data corresponding to the display gradation of a certain frame and gradation data corresponding to the display gradation to be displayed in the next frame. By applying a voltage corresponding to the corrected gradation data to the liquid crystal, the response speed of the liquid crystal is increased. The technique described in the above-mentioned Patent Document 3 uses display data (gradation data) by a predetermined conversion method. ) Is corrected, and the response speed of the liquid crystal is increased by applying a voltage corresponding to the corrected gradation data to the liquid crystal. For this reason, the techniques described in Patent Document 2 and Patent Document 3 have a problem that a complicated circuit using an arithmetic circuit, a correction data table, and the like is necessary for generating the correction gradation data.

  The present invention has been made to solve the above-mentioned problems in the prior art, and solves the problem of the response speed of the liquid crystal more simply than before, and improves the blurring of moving images generated in the liquid crystal display device. The purpose is to provide technology.

In order to solve at least a part of the above-described problems, a liquid crystal display device of the present invention includes:
A liquid crystal display device that displays an image represented by an input image signal,
A liquid crystal unit having liquid crystal pixels arranged in a matrix;
One frame period corresponding to one period of the vertical synchronization signal indicating the vertical synchronization timing of the input image signal is divided into a plurality of subframe periods, and sequential selection of each row of the liquid crystal pixels is repeated for each subframe period. A vertical drive to perform,
Among the plurality of subframe periods, in a specific subframe period including one of a first subframe period and a last subframe period, specific image data is generated as the drive image data, and the specific subframe In another subframe period excluding the period, a drive image data generation unit that generates display image data corresponding to the image data included in the input image signal as the drive image data;
In the specific subframe period, a specific pixel voltage corresponding to the specific image data supplied as the drive image data is applied to the liquid crystal pixels in each column of each row that are sequentially selected, and the other In the subframe period, a horizontal driving unit that applies a pixel voltage corresponding to image data based on the input image signal supplied as the driving image data to the liquid crystal pixels in each column of each row that is sequentially selected;
With
The specific pixel voltage has a magnitude equal to or less than a minimum value that can be taken as a pixel voltage corresponding to image data based on the input image signal.

  According to the liquid crystal display device, it is possible to improve the blurring of moving images generated in the image display device with a simple configuration as compared with the case of the prior art.

The liquid crystal pixels are set to a normally black mode,
The specific image data may be set to image data representing a gradation value lower than the gradation value of the display image data representing a black level,
In addition, the liquid crystal pixel is set to a normally white mode,
The specific image data may be set to image data representing a gradation value higher than the gradation value of the display image data representing the white level.

When the liquid crystal pixel is set to a normally white mode,
On the back surface of the liquid crystal unit, the liquid crystal unit is divided into a plurality of illumination regions along the direction of the row, and includes an illumination device that illuminates each illumination region independently,
It is preferable that the illumination device does not illuminate an illumination area corresponding to a row in which a pixel voltage corresponding to the specific image data is applied and held.

  If it does as mentioned above, the fall of contrast can be controlled.

The illumination device may include a shutter that opens and closes independently for each illumination area.
The lighting device may include a plurality of lamps that are turned on and off independently for each lighting area.

In any configuration, the liquid crystal unit can be easily divided into a plurality of illumination areas along the row direction, and each illumination area can be illuminated independently,
An illumination area corresponding to a row in which a pixel voltage corresponding to specific image data is applied and held can be made non-illuminated.

  Note that the present invention is not limited to the above-described aspect of the liquid crystal display device, and can also be realized as an aspect of a method invention such as a driving method of the liquid crystal display device.

Hereinafter, embodiments of the present invention will be described in the following order based on examples.
A. First embodiment:
A1. Configuration of the liquid crystal display device:
A2. Driving operation of liquid crystal display device:
A3. Lighting operation of the liquid crystal display device:
B. Second embodiment:
B1. Configuration of the liquid crystal display device:
B2. Driving operation of liquid crystal display device:
C. Variations:

A. First embodiment:
A1. Configuration of the liquid crystal display device:
FIG. 1 is an explanatory diagram showing a schematic configuration of a liquid crystal display device as a first embodiment of the present invention. The liquid crystal display device 1000 includes an input processing unit 100, a drive image data generation unit 200, a drive timing control unit 300, a liquid crystal panel unit 410, a vertical drive unit 420 that controls the operation of the liquid crystal panel unit 410, and a horizontal drive. A light source (not shown), an illumination shutter 510, and a shutter drive unit 520 that constitute the illumination device. The illumination shutter 510 is disposed on the back side of the liquid crystal panel unit 410, and a light source (not shown) is disposed such that illumination light emitted from the light source illuminates the liquid crystal panel unit 410 via the illumination shutter 510. Has been.

  The input processing unit 100 samples the image data included in the input image signal VSIN based on a timing signal indicating the synchronization timing of each pixel, performs various image processing, and inputs the image data to the driving image data generation unit 200. The image data signal PS is converted into a possible image data signal PS and output to the drive image data generation unit 200. The input processing unit 100 also supplies the pixel clock signal IPXCK, the horizontal synchronization signal IHSYNK, and the vertical synchronization signal IVSYNK to the drive timing control unit 300 as timing signals (synchronization signals) indicating the synchronization timing of the image data signal PS. Output.

  When the input image signal VSIN is an analog image signal, the input image signal VSIN is sampled with a clock signal generated based on a horizontal synchronization signal (not shown) input at the same time, and converted into digital image data. Converted. The sampled digital image data is output as an image data signal PS using the pixel clock signal IPXCK, the horizontal synchronization signal IHSYNK, and the vertical synchronization signal IVSYNK as timing signals. However, when the input image signal VSIN is a digital image signal, the input image signal VSIN is sampled as it is based on a pixel clock signal (not shown) input at the same time.

  The drive image data generation unit 200 includes a line buffer 210, a frame memory 220, a gradation conversion unit 230, and a selector 240.

  The line buffer 210 is a memory for temporarily storing image data corresponding to the number of pixels corresponding to one horizontal line (hereinafter, simply referred to as “one line”) of the image represented by the image data signal PS. The line buffer 210 converts the image data of each pixel included in the image data signal PS (hereinafter also simply referred to as “image data PS”) into the write control signal LWCTL supplied from the drive timing control unit 300. On the basis of this, they are sequentially captured and stored in the cycle of the pixel clock signal IPCK. In addition, the line buffer 210 receives the sequentially written image data PS of the double-speed clock signal 2XPCK having a double-speed cycle of the pixel clock signal IPCK based on the read control signal LRCTL supplied from the drive timing control unit 300. The data are sequentially read in a cycle and output to the frame memory 220 as an image data signal WPS. As described above, the line buffer 210 has a function of converting the input image data signal PS from the image data signal having the pixel period of the pixel clock signal IPCK to the image data signal WPS having the pixel period of the double speed clock signal 2XPCK. is doing.

  The frame memory 220 is a memory for temporarily storing a number of image data corresponding to the number of pixels for one frame included in the image data signal WPS. The frame memory 220 uses the image data of each pixel included in the image data signal WPS (hereinafter also simply referred to as “image data WPS”) as a write control signal FWCTL supplied from the drive timing control unit 300. On the basis of this, they are sequentially captured and stored in the cycle of the double-speed clock signal 2XPCK. Further, the frame memory 220 sequentially reads the sequentially written image data WPS in the cycle of the double-speed clock signal 2XPCK based on the read control signal FRCTL supplied from the drive timing control unit 300, and the gradation conversion unit 230 More specifically, after the gradation conversion, a conversion process for extending the bit width is performed, and the image data signal RPS is output to the selector 240.

  The selector 240 receives an image data signal RPS input from the frame memory 220 via the gradation conversion unit 230 and a specific image data signal OWS representing specific image data set in advance. Based on the selection signal SBF supplied from the timing controller 300, either the image data signal RPS or the specific image data signal OWS is selected and output as the drive image data signal DPS. The specific image data included in the specific image data signal OWS (hereinafter, also simply referred to as “specific image data OWS”) is image data RPS input via the gradation conversion unit 230, as will be described later. Is set to data corresponding to a gradation value higher than the gradation value set as the white level gradation value (hereinafter referred to as “overwhite data”). .

  The generation timing of the drive image data signal DPS in the drive image data generation unit 200 will be further described later.

  Based on the pixel clock signal IPCK, the horizontal synchronization signal IHSYNC, and the vertical synchronization signal IVSYNC, the drive timing control unit 300 generates a write control signal LWCTL and a read control signal LRCTL from the line buffer 210, and a write control signal FWCTL from the frame memory 220. The vertical drive control signal VCTL for controlling the operation of the vertical drive unit 120 and the horizontal drive for controlling the operation of the horizontal drive unit 130 while generating the read control signal FRCTL and the selection signal SBF of the selector 240. A control signal HCTL.

  The liquid crystal panel unit 410 includes m scanning lines Y # m (m = 1, 2, 3,...) Wired in parallel along the horizontal direction (horizontal direction) of the paper, and the vertical direction (vertical direction) of the paper. N data lines X # n (n = 1, 2, 3,...) Wired in parallel along the line, and each portion at the intersection of each scanning line and data line has a normally White mode liquid crystal pixels 412 are arranged in a matrix, which corresponds to the liquid crystal portion of the present invention, and each liquid crystal pixel 412 is a thin film transistor (Thin Film Transistor) as shown enlarged in a circle indicated by a one-dot chain line. (Hereinafter referred to as “TFT”) 414, and is connected to the scanning line and the data line that form each intersection. Specifically, the gate electrode of the TFT 414 is connected to the scanning line, and the source electrode is connected to the scanning line. Connected to the data line, drain electrode connected to the pixel electrode of the liquid crystal pixel 412 That.

  Here, when a scanning signal is given to a scanning line connected to a certain TFT 414, the TFT 414 becomes conductive, and the liquid crystal pixel 412 connected to the TFT 414 is connected to the data line connected to the TFT 414. By applying a predetermined analog voltage (hereinafter also referred to as “pixel voltage”), image data corresponding to the pixel voltage is written. The liquid crystal pixel 412 to which a predetermined pixel voltage is applied changes to the light transmittance corresponding to the voltage. And the light irradiated from the back surface is permeate | transmitted according to the transmittance | permeability. As a result, the liquid crystal panel unit 410 can display an image corresponding to the image data written in each liquid crystal pixel 412.

  Based on the vertical drive control signal VCTL supplied from the drive timing control unit 300, the vertical drive unit 420 is activated by sequentially supplying scan signals to m scan lines Y # m for each subframe described later. By making (active), all TFTs 414 connected to the activated scanning line are turned on, and each liquid crystal pixel 412 connected via each turned-on TFT 414 is moved along the scanning line. Select in line units (line units).

  The horizontal drive unit 430 generates a pixel voltage corresponding to drive image data (hereinafter, also simply referred to as “drive image data DPS”) represented by the drive image data signal DPS supplied from the drive image data generation unit 200, as a drive timing control unit. Based on the horizontal drive control signal HCTL supplied from 300, the voltage is applied to each liquid crystal pixel 412 connected to the scanning line activated by the vertical drive unit 420 via the corresponding data line. Thus, the corresponding driving image data is written.

  The illumination shutter 510 includes a plurality of micro shutters arranged corresponding to the respective liquid crystal pixels 412 of the liquid crystal panel unit 410. Each micro-shutter controls irradiation of each liquid crystal pixel with illumination light emitted from a light source (not shown). As this illumination shutter 510, for example, FIXEL Ltd. A company-made Flexel array can be used.

  The shutter drive unit 520 controls the opening / closing of the micro shutter of the illumination shutter 510 based on the shutter drive control signal SCTL supplied from the drive timing control unit 300, and each liquid crystal pixel 412 of the liquid crystal panel unit 410 as described later. Illuminate.

  The liquid crystal display device 1000 having the configuration described above is driven according to the driving operation described below, and displays an image represented by the input image signal.

A2. Driving operation of liquid crystal display device:
Hereinafter, the driving operation of the liquid crystal display device 1000 having the above configuration will be described.

  FIG. 2 is an explanatory diagram showing a scanning line selection operation by the vertical drive unit. FIG. 2 is representative of the period of each frame. The Nth (N is an integer equal to or greater than 1) frame (hereinafter referred to as “N frame”) and the (N + 1) th frame (hereinafter referred to as “(N + 1)”. ) Frame))).

  As shown in FIG. 2, the vertical driver 420 (FIG. 1) divides the period of each frame into a period of the first subframe 1 and a period of the second subframe 2, and scans in the period of the first subframe 1. The line Y # 1 to the scanning line Y # m are sequentially selected (scanned), and the scanning line Y # 1 to the scanning line Y # m are sequentially selected even in the second subframe 2 period. As a result, in the period of each frame, each scanning line is selected twice at a subframe interval (hereinafter also referred to as “subframe interval”) that is approximately half of one frame, and is selected as described later. Corresponding image data is written to each liquid crystal pixel in a row connected to the scanning line.

  FIG. 3 is an explanatory diagram showing the drive image data generation operation by the drive image data generation unit and the drive image data write operation by the horizontal drive unit. FIG. 3 shows the period of N frames and the period of (N + 1) frames on behalf of the period of each frame, as in FIG. 3A shows the vertical synchronization signal IVSYNC indicating the vertical synchronization timing of the input image signal VSIN, FIG. 3B shows the horizontal synchronization signal IHSYNC indicating the horizontal synchronization timing of the input image signal VSIN, and FIG. 3C shows the input image signal. The image data signal PS corresponding to VSIN, (d) the image data signal WPS output from the line buffer 210, and (e) the image data signal RPS output from the frame memory 220 via the gradation conversion unit 230. (F) is a selection signal SBF that changes according to the subframe period, (g) is a drive image data signal DPS output from the selector 240, and (h) is a scanning line Y # 1 of the first line. The image data written to the selected liquid crystal pixel line (hereinafter referred to as “line 1”), (i) is the [p + 1] th (p is m / 2). Corresponding image data to be written to the liquid crystal pixel line selected by the scanning line Y # [P + 1] (hereinafter referred to as “line [P + 1]”), (j) is the [2p] line. Image data to be written in a liquid crystal pixel line (hereinafter referred to as “line [2p]”) selected by the scanning line Y # [2p] is shown.

  In the image data signal PS output from the input processing unit 100, as shown in FIG. 3C, the image data corresponding to each liquid crystal pixel in each line includes the vertical synchronization signal IVSYNC (FIG. 3A). In the period (frame period) of each period (also referred to as “frame period”), the period (pixel period) of the pixel clock signal IPCK (not shown) in the period of the horizontal synchronization signal IHSYNC (FIG. 3B) corresponding to each line. ), In order. For convenience of explanation and illustration, illustration of pixel-unit image data is omitted.

  The image data of each line included in the image data signal PS is sequentially written in the line buffer 210 (FIG. 1) in the cycle of the pixel clock signal IPCK in each cycle corresponding to the horizontal synchronization signal IHSYNC.

  Then, as shown in FIG. 3D, the image data written in the line buffer 210 is sequentially read out in the cycle of the double-speed clock signal 2XPCK (not shown) in each cycle corresponding to the horizontal synchronization signal IHSYNC. Output as data signal WPS. Note that reading of the image data included in the image data signal WPS is executed by reading the image data sequentially written in the cycle of the pixel clock signal IPCK in the cycle of the double-speed clock signal 2XPCK, so that the reading overtakes the writing. It is executed in the second half of each period of the horizontal synchronizing signal IHSYNC so that there is no such thing.

  Each image data included in the image data signal WPS is sequentially written in the frame memory 220 in a cycle of the double speed clock signal 2XPCK in each cycle corresponding to the horizontal synchronization signal IHSYNC.

  Here, as shown in FIG. 3E, the selection signal SBF is a period during which image data corresponding to the first half line from the line 1 to the line [p] is read as the image data signal WPS, that is, one frame. Becomes the high level (low level) in the first half of subframe 1 and the period in which the image data corresponding to the second half of the line from [P + 1] to [2p] is read as the image data signal WPS, that is, 1 It is set to be low level (high level) in the period of subframe 2 in the second half of the frame.

  Then, the image data written in the frame memory 220 is sequentially read out in the period of the double speed clock signal 2XPCK in the period of the subframe 2 and output as the image data signal RPS as shown in FIG. The

  The image data signal RPS read from the frame memory 220 is output as the drive image data signal DPS by the selector 240 in the period of the subframe 2 as shown in FIG. On the other hand, in the period of subframe 1, the specific image data signal OWS representing the above-described overwhite level is output as the drive image data signal DPS. That is, the specific image data signal OWS representing the overwhite level is output as the drive image data signal DPS in the subframe 1 period, and the image data signal RPS read from the frame memory 220 is driven in the subframe 2 period. It is output as an image data signal DPS.

  As shown in FIGS. 3 (h), (i), and (j), the liquid crystal pixels in each line are based on the drive image data signal DPS output from the drive image data generation unit 200 as described above. When the corresponding scanning line is selected, the specific image data indicating the over-white level is written in the period of the subframe 1 and held until the original image data is written in the period of the next subframe 2. The However, actually, the specific image data is not directly written, but a specific pixel voltage corresponding to the specific image data is applied and held. In the period of subframe 2, the corresponding original image data is written and held until the specific image data representing the over-white level is written in the period of the next subframe 1. However, similarly, the actual image data is not actually written directly, but a pixel voltage corresponding to the original image data is applied and held. The pixel voltage corresponding to the image data is actually applied in an alternating manner in synchronization with the period of the horizontal synchronization signal, the period of the vertical synchronization signal, the period of the pixel clock signal, etc. Since there is no particular relationship above, it is ignored.

  FIG. 4 is an explanatory diagram showing image data written to a certain liquid crystal pixel and the transmittance of the liquid crystal pixel. As shown in FIG. 4, in a certain liquid crystal pixel, a specific image data holding period (hereinafter referred to as a “specific image data period”) representing an overwhite level written in the period of the subframe 1 described above, The original image data holding period written in the subframe 2 period (hereinafter referred to as “display image data period”) is alternately repeated. As a result, the transmittance of the liquid crystal pixel is once set to the transmittance corresponding to the specific image data of the over-white level in the specific image data period, and then to the transmittance corresponding to the original image data in the display image data period. The The length of the specific image data period corresponds to the length of the subframe 1 period, the length of the display image data period corresponds to the length of the subframe 2 period, and the generation interval of each period is any Is also equal to the frame period.

  Here, for example, in the case of a TN liquid crystal, the liquid crystal pixel is applied from a state in which no pixel voltage is applied to the liquid crystal pixel (hereinafter referred to as “off state”) (hereinafter referred to as “on state”). It is known that a relatively high-speed response characteristic is exhibited in the case of a change to an on-state, but a considerably low-speed response characteristic is exhibited in the case of a change from an on state to an off state. A normally white mode liquid crystal has the highest transmittance in the off state and the lowest transmittance in the on state.

  Therefore, as described above, before writing the original image data, specific image data of an overwhite level that is a gradation value higher than the white level, for example, an image in which the pixel voltage applied to the liquid crystal pixel is “0” By writing the data, the change in the state of the liquid crystal pixels when the original image data is written can always be changed from the off state side (high transmittance side) to the on state side (low transmittance side). Response characteristics when original image data is written to each liquid crystal pixel can be improved.

  In the above-described embodiment, the specific image data is described as image data having an overwhite level that is higher than the gradation value set as the white level. However, the gradation set as the white level is described. Value image data may be used. In this case, the gradation conversion unit can be omitted.

A3. Lighting operation of the liquid crystal display device:
By the way, as described above, each liquid crystal pixel is in an excessive transmittance state in which specific image data having an overwhite level is always written in the specific image data period, so the liquid crystal pixel in which the specific image data is written. When the illumination light is irradiated, the black level side of the displayed image becomes brighter, resulting in a bright image with low contrast as a whole. Therefore, the illumination of each liquid crystal pixel is effectively displayed as a non-illumination period in the specific image data period, and an original image is displayed as the illumination period in the display image data period. Is preferred. Specifically, the micro shutter of the illumination shutter 510 described above is opened and closed as described below so that the illumination light is not irradiated to the liquid crystal pixels in which the specific image data is written and held. The illumination period and the non-illumination period can be controlled.

FIG. 5 is an explanatory diagram showing an illumination operation of each liquid crystal pixel. In FIG. 5, for ease of explanation, the number of liquid crystal pixel lines is assumed to be six. FIG. 5 shows the illumination operation in the period of N frames and the period of (N + 1) frames, representing the period of each frame.

  In the period of the subframe 1, the first line 1 to the last line 6 are selected (scanned) in order in units of lines, and specific image data with an overwhite level is written respectively. In FIG. 5, a line in which image data is actually being written is indicated by a dashed arrow. At this time, the lines are not illuminated in the order of the lines where writing starts. In FIG. 5, lines that are actually not illuminated are shown by cross-hatching.

  Then, in the period of subframe 2, the first line 1 to the last line 6 are again selected in line units, and the original image data corresponding to each line is written in order. At this time, each line is illuminated in the order of the lines on which writing is performed.

  As described above, by controlling the opening and closing of the micro shutter corresponding to each liquid crystal pixel of the illumination shutter 510, the line in which the over-white level specific image data is written is not illuminated, and the line in which the original image data is written Can be illuminated. As a result, before the new image is displayed, the illumination light is temporarily shielded to effectively erase the visual influence of the previously displayed image, and then the new image is displayed. Therefore, it is possible to suppress blurring of a moving image generated due to the liquid crystal being a hold-type electro-optical element as described in the related art.

B. Second embodiment:
B1. Configuration of the liquid crystal display device:
FIG. 6 is an explanatory diagram showing a schematic configuration of a liquid crystal display device as a second embodiment of the present invention. The liquid crystal display device 1000A includes an input processing unit 100, a drive image data generation unit 200, a drive timing control unit 300A, a liquid crystal panel 400, a light source (not shown), an illumination shutter 510, and a shutter drive that constitute an illumination device. Part 520.

  The liquid crystal panel 400 includes a drive control unit that controls operations of the vertical drive unit 420 and the horizontal drive unit 430 in addition to the liquid crystal panel unit 410, the vertical drive unit 420, and the horizontal drive unit 430. It functions as.

  The liquid crystal display device 1000A according to the present embodiment uses a single liquid crystal device to form a liquid crystal display device, so that a read control signal FRCTL is supplied from the drive timing control unit 300A to the frame memory 220 of the drive image data generation unit 200. And the vertical drive control signal VCTL is supplied to the vertical drive unit 420 and the horizontal drive control signal HCTL is not supplied to the horizontal drive unit 430, but the drive control signal DCTL is supplied to the drive control unit 440. Is basically the same as the liquid crystal display device 1000 of the first embodiment except for the point that it is supplied.

B2. Driving operation of liquid crystal display device:
FIG. 7 is an explanatory diagram illustrating the drive image data generation operation by the drive image data generation unit and the drive image data write operation by the horizontal drive unit. 7A to 7J represent the same signals as in FIGS. 3A to 3J. FIG. 7A shows the vertical synchronization signal IVSYNC, and FIG. 7B shows the horizontal synchronization signal IHSYNC. (C) is the image data signal PS, (d) is the image data signal WPS, (e) is the image data signal RPS, (f) is the selection signal SBF, (g) is the drive image data signal DPS. (H) shows image data written to the line 1, (i) shows image data written to the line [P + 1], and (j) shows image data written to the line [2p]. Further, (k) and (l) indicate the vertical synchronization signal DVSYNC and the horizontal synchronization signal DHSYNC included in the drive control signal DCTL of the liquid crystal panel 400.

  In the present embodiment, as shown in FIG. 7 (k), the period is synchronized with the vertical synchronization signal IVSYNC and has a period ([1 / 2V]) that is half the period ([1V]) of the vertical synchronization signal IVSYNC. Control including the vertical synchronization signal DVSYNC, the horizontal synchronization signal DHSYNC having a period half the period of the horizontal synchronization signal IHSYNC, and the pixel clock signal DCK equal to the double speed clock signal 2XPCK shown in FIG. The signal DCTL is input to the drive control unit 440 of the liquid crystal panel 400 to operate the vertical drive unit 420 and the horizontal drive unit 430 at double speed.

  Then, as shown in FIG. 7 (f), the image data signal WPS output from the frame memory 220 via the gradation converting unit 230 is converted into a vertical synchronization signal DVSYNC (FIG. 7 (k) corresponding to the period of the subframe 2. )) In the cycle of the horizontal synchronization signal DHSYNC (FIG. 7 (l)), the image data of the corresponding lines are sequentially output.

  Even when operated as described above, the specific image data signal OWS representing the over-white level is output as the drive image data signal DPS in the period of the vertical synchronization signal DVSYNC corresponding to the period of the subframe 1, and the subframe 2 In the period of the period of the vertical synchronization signal DVSYNC corresponding to this period, the corresponding image data signal RPS is output as the drive image data signal DPS.

  Further, based on the drive image data signal DPS output from the drive image data generation unit 200, the liquid crystal pixels of each line are scanned correspondingly as shown in FIGS. 7 (h), (i), and (j). When a line is selected, specific image data representing an over-white level is written and held in the subframe 1 period, and corresponding image data is written and held in the subframe 2 period.

  Therefore, also in the present embodiment, as described above, the original image data is written by writing the specific image data of the over-white level that is the gradation value higher than the white level before writing the original image data. In this case, the change in the state of the liquid crystal pixel can always be changed from the off-state side (high transmittance side) to the on-state side (low transmittance side), so when original image data is written to each liquid crystal pixel Response characteristics can be improved.

C. Variations:
In addition, this invention is not restricted to said Example and embodiment, In the range which does not deviate from the summary, it is possible to implement in various aspects.

C1. Modification 1:
In the above embodiment, a direct-view type liquid crystal display device is described as an example. However, the liquid crystal device is used as a light valve, and light (image light) representing an image emitted from the liquid crystal device is used by a projection optical system. By forming an image on the projection screen, it is possible to provide a projector that projects an image on the projection screen SC.

C2. Modification 2:
In the above embodiment, one frame period is divided into two subframe periods, the specific image data of the over-white level is written in the first half subframe 1 period, and the original image data is written in the second half subframe 2 period. Although the case has been described as an example, the original image data may be written in the period of the first half of the subframe 1, and the specific image data of the over-white level may be written in the period of the second half of the subframe 2. Even in this case, before the original image data is written, the specific image data of the over-white level having a gradation value higher than the gradation value set as the white level is written, and the original image data is written. In this case, the change in the state of the liquid crystal pixel can always be changed from the off-state side (high transmittance side) to the on-state side (low transmittance side), so when original image data is written to each liquid crystal pixel Response characteristics can be improved.

C3. Modification 3:
In the above embodiment, the case where one frame period is divided into two subframe periods has been described as an example, but one frame period is divided into three or more subframe periods, and the first subframe period or In a specific subframe period including the last subframe period, specific image data having an overwhite level may be written and held, and original image data may be written and held in another subframe period.

  FIG. 8 is an explanatory diagram showing image data written to a certain liquid crystal pixel and transmittance of the liquid crystal pixel when one frame period is divided into three subframe periods. FIG. 8 shows a case where the specific image data is written and held in the period of subframe 1 and the original image data is written and held in the periods of subframes 2 and 3. In this case, the original image data written in the period of subframe 2 is held for the length of the specific image display period in which the specific image data written in the period of subframe 1 is held. Since the length of the display image data period (corresponding to the length corresponding to the periods of subframe 2 and subframe 3) can be increased, the liquid crystal pixels in the display image data period are illuminated. , Effective in suppressing flicker.

  FIG. 9 is another explanatory diagram showing image data written to a certain liquid crystal pixel and transmittance of the liquid crystal pixel when one frame period is divided into three subframe periods. FIG. 9 also shows the case where the specific image data is written and held in the period of subframe 1 and the original image data is written and held in the periods of subframes 2 and 3 as in FIG. As shown in FIG. 9, the response speed of the change from the off-state side to the on-state side of the liquid crystal, specifically, the response speed of the transmittance corresponding to the image data written in the original subframe 2 period, The response speed of the change from the on-state side to the off-state side of the liquid crystal, specifically, the response speed of the transmittance corresponding to the specific image data written in the period of the subframe 1 is slower than that. May be a problem. In this case, as shown in FIG. 9, in the display image data period, the original image data is written and the transmittance is changed, in this case, the length of the subframe 2 period. During the period corresponding to the non-illumination of the corresponding liquid crystal pixel, the period corresponding to the length of the subframe 3 in this case, the period corresponding to the length of the subframe 3 What is necessary is just to illuminate the liquid crystal pixel to perform. In this way, it is possible to suppress the blurring of the moving image caused by the response characteristics of the liquid crystal and the hold-type element as described in the prior art. However, in this case, since the illumination period in one frame period, that is, the period during which an image is actually displayed is shortened, flicker tends to increase.

  If the response speed of the transmittance corresponding to the specific image data is a problem, the specific image data is written in the first consecutive subframe periods, or the last consecutive multiple The specific image data may be written in the subframe period. However, when the display image data period in which the original image data is written and held is shorter than the specific image data period in which the specific image data is written and held, the illumination period in one frame period, that is, Since the period during which an image is actually displayed is shortened, flicker tends to increase.

C4. Modification 4:
In the above embodiment, the liquid crystal operating in the normally white mode has been described as an example. However, the liquid crystal operating in the normally black mode may be used. In this case, image data representing a gradation value equal to or lower than the gradation value set as the black level may be written as the specific image data. In this case, the illumination shutter can be omitted.

C5. Modification 5:
In the above-described embodiment, the illumination apparatus including the illumination shutter 510 including the micro-shutter corresponding to each liquid crystal pixel is described as an example. However, the present invention is not limited to this. An illumination shutter having a shutter controlled in units of rows may be used, and any illumination shutter can be used as long as a liquid crystal pixel to which a pixel voltage corresponding to specific image data is applied and held can be non-illuminated. It doesn't matter.

  In addition, a liquid crystal pixel including a plurality of lamps corresponding to a plurality of illumination areas obtained by dividing each liquid crystal pixel along a row (horizontal line) direction, and a pixel voltage corresponding to specific image data being applied and held The illumination area corresponding to this row may be unilluminated.

  In other words, a plurality of illumination areas obtained by dividing each liquid crystal pixel along the direction of a row (horizontal line) can be illuminated independently, and a liquid crystal pixel to which a pixel voltage corresponding to specific image data is applied and held Various illumination devices can be used as long as the illumination area corresponding to can be made non-illuminated.

It is explanatory drawing which shows schematic structure of the liquid crystal display device as 1st Example. It is explanatory drawing shown about the selection operation | movement of the scanning line by a vertical drive part. It is explanatory drawing which shows the drive image data production | generation operation | movement by a drive image data production | generation part, and the write operation of the drive image data by a horizontal drive part. It is explanatory drawing which shows the image data written in a certain liquid crystal pixel, and the transmittance | permeability of the liquid crystal pixel. It is explanatory drawing shown about the illumination operation | movement of each liquid crystal pixel. It is explanatory drawing which shows schematic structure of the liquid crystal display device as 2nd Example. It is explanatory drawing which shows the drive image data production | generation operation | movement by a drive image data production | generation part, and the write operation of the drive image data by a horizontal drive part. It is explanatory drawing which shows the image data written in the liquid crystal pixel when one frame period is divided | segmented into three sub-frame periods, and the transmittance | permeability of the liquid crystal pixel. It is another explanatory drawing which shows the image data written in the liquid crystal pixel when one frame period is divided into three sub-frame periods, and the transmittance of the liquid crystal pixel.

Explanation of symbols

1000 ... Liquid crystal display device 1000A ... Liquid crystal display device 100 ... Input processing unit 200 ... Drive image data generation unit 210 ... Line buffer 220 ... Frame memory 230 ... Tone conversion unit 240 ... selector 300 ... drive timing control unit 300A ... drive timing control unit 400 ... liquid crystal panel unit 410 ... liquid crystal panel 412 ... liquid crystal pixel 414 ... TFT
420 ... Vertical drive unit 430 ... Horizontal drive unit 440 ... Drive control unit 510 ... Illumination shutter 520 ... Shutter drive unit

Claims (7)

A liquid crystal display device that displays an image represented by an input image signal,
A liquid crystal unit having liquid crystal pixels arranged in a matrix;
One frame period corresponding to one period of the vertical synchronization signal indicating the vertical synchronization timing of the input image signal is divided into a plurality of subframe periods, and sequential selection of each row of the liquid crystal pixels is repeated for each subframe period. A vertical drive to perform,
Among the plurality of subframe periods, in a specific subframe period including one of a first subframe period or a last subframe period, specific image data set in advance is output as drive image data, and In other subframe periods excluding a specific subframe period, a drive image data generation unit that outputs image data based on the input image signal as the drive image data;
In the specific subframe period, a specific pixel voltage corresponding to the specific image data supplied as the drive image data is applied to the liquid crystal pixels in each column of each row that are sequentially selected, and the other In the subframe period, a horizontal driving unit that applies a pixel voltage corresponding to image data based on the input image signal supplied as the driving image data to the liquid crystal pixels in each column of each row that is sequentially selected;
With
The liquid crystal display device, wherein the specific pixel voltage has a magnitude equal to or smaller than a minimum value that can be taken as a pixel voltage corresponding to image data based on the input image signal. The liquid crystal display device according to claim 1,
The liquid crystal pixel is set to a normally black mode,
The liquid crystal display device, wherein the specific image data is set to image data representing a gradation value equal to or less than a gradation value of the display image data set as a black level. The liquid crystal display device according to claim 1,
The liquid crystal pixel is set to a normally white mode,
The liquid crystal display device, wherein the specific image data is set to image data representing a gradation value equal to or higher than a gradation value of the display image data set as a white level. The liquid crystal display device according to claim 3,
On the back surface of the liquid crystal unit, the liquid crystal unit is divided into a plurality of illumination regions along the direction of the row, and includes an illumination device that illuminates each illumination region independently,
The liquid crystal display device characterized in that the illumination device unilluminates an illumination region corresponding to a row in which a pixel voltage corresponding to the specific image data is applied and held. The liquid crystal display device according to claim 4,
The illumination device includes a shutter that opens and closes independently for each illumination region. The liquid crystal display device according to claim 4,
The illumination device includes a plurality of lamps that are turned on and off independently for each illumination area. A driving method of a liquid crystal display device having liquid crystal pixels arranged in a matrix and displaying an image represented by an input image signal,
One frame period corresponding to one period of the vertical synchronization signal indicating the vertical synchronization timing of the input image signal is divided into a plurality of subframe periods, and sequential selection of each row of the liquid crystal pixels is repeated for each subframe period. Run,
Among the plurality of subframe periods, in one specific subframe period of either the first subframe period or the last subframe period, specific image data is generated as the drive image data, and the specific subframe period In other subframe periods except for, display image data corresponding to image data included in the input image signal is generated as the drive image data,
In the specific subframe period, a specific pixel voltage corresponding to the specific image data supplied as the drive image data is applied to the liquid crystal pixels in each column of each row that are sequentially selected, and the other In the subframe period, a pixel voltage corresponding to image data based on the input image signal supplied as the drive image data is applied to the liquid crystal pixels in each column of each row that is sequentially selected,
The driving method according to claim 1, wherein the specific pixel voltage has a magnitude equal to or smaller than a minimum value that can be taken as a pixel voltage corresponding to image data based on the input image signal.

Images