JP5398037B2 - Driving circuit, image display apparatus, and driving method - Google Patents

Description

    The present invention relates to a drive circuit, an image display device, and a drive method.

    In a general liquid crystal display device including a liquid crystal display element having a plurality of pixels and an illumination device that irradiates light to the liquid crystal display element, an image is displayed by modulating the illumination light using the liquid crystal display element. It is carried out. Among the general image display methods of a liquid crystal display device, a direct view type in which an image is directly displayed by light modulated by a liquid crystal display element, and an image is displayed by projecting light modulated by the liquid crystal display element onto a screen. Projection type exists.

    Further, as a method for performing color display in a liquid crystal display device, color generation methods such as juxtaposed (parallel) additive color mixture, simultaneous additive color mixture, and continuous additive color mixture are used.

    As a method of color display using juxtaposed (parallel) additive color mixing, pixels (sub-pixels) having color filters of R color (red), G color (green), and B color (blue) are arranged close to each other. There is a method of using a configured pixel for color display. In each pixel for color display, the arrangement interval between adjacent sub-pixels is set to be narrower than the detection limit of the spatial resolution of the user's eyes at a predetermined observation position. By modulating light using such color display pixels, the user is made to recognize various colors. In a direct-view type liquid crystal display device, a color display method using a juxtaposed (parallel) additive color mixture is generally used.

    In addition, as a method of performing color display using simultaneous additive color mixture, each liquid crystal display has a liquid crystal display element that modulates light of each of R color (red), G color (green), and B color (blue). There is a type that displays an image by superimposing light modulated into each color by an element. In a projection type liquid crystal display device (liquid crystal projector), a so-called “three-plate type liquid crystal projector” is generally used, and the color display method uses simultaneous additive color mixing.

    In addition, as a color display method using continuous additive color mixing, there is a so-called “FSC (Field Sequential Color) method” (for example, Japanese Patent Application Laid-Open Nos. 2005-024755 and 2006-163358). And Japanese Patent Publication No. 2007-171567.)

    The “FSC system” is a field for displaying a plurality of field images constituting a frame image in one frame period (for example, 1/60 seconds) for displaying a frame image as one completed image. For each period (for example, 1/180 second), images of gradation levels set for different colors (for example, R, G, and B, which are primary colors) are sequentially applied to the same pixel of the liquid crystal display element. It is a method to display on. In the FSC method, the field period for displaying each color field image is set shorter than the detection limit of the time resolution of the human eye, and the field image is switched and displayed every time the field period elapses. To recognize various colors.

    When the FSC method is applied to a direct-view type liquid crystal display device, effects such as a reduction in manufacturing cost and an improvement in resolution can be expected from the advantage that a color filter and sub-pixels are unnecessary in configuration. In addition, when the FSC system is applied to a projection type liquid crystal display device, it can be constituted by a monochrome single plate (one liquid crystal display element not equipped with a color filter), so that an effect such as downsizing of the liquid crystal display device is expected. .

    Note that in the FSC method in which field images of a plurality of colors are sequentially displayed on a single monochrome liquid crystal display element as the field period elapses, the liquid crystal display element responds faster than other color generation methods. There is also a need for a lighting device that switches between multiple colors of light as well as required. Illumination devices capable of such switching operations include, for example, illumination devices composed of a white light source and a color wheel, and LEDs (Light Emitting Diodes) that output monochromatic light (R color light, G color light, or B color light), respectively. An illumination device configured from a solid light source such as) is known.

    Incidentally, a general liquid crystal display device has the following features [1] to [5].

    Feature [1]: The liquid crystal display element has a slow optical response (light transmittance response).

    Characteristic [2]: Since a p-Si (polycrystalline silicon) TFT (Thin Film Transistor) circuit formed in the liquid crystal display element has a low operating frequency, it takes time to transfer image data.

    Feature [3]: The image data input to the liquid crystal display element is immediately applied to the corresponding pixel, and the liquid crystal of the pixel starts to respond.

    Feature [4]: All the pixels of the liquid crystal display element are simultaneously illuminated with the same color light.

    Feature [5]: When the gradation displayed on the liquid crystal display element changes from the black level (gradation level 0%) to the white level (gradation level 100%) and from the white level to the black level The response characteristics of the light transmittance are different from each other.

    First, the feature [5] will be described.

    The liquid crystal display device has a liquid crystal mode such as a TN (Twisted Nematic) mode, an IPS (In-Plane Switching) mode, a VA (Vertically Aligned) mode, and an OCB (Optically Compensated Bend) mode. In either case, the direction of the liquid crystal (director) is changed by the applied electric field to control the degree of birefringence, and the polarization state of the light passing through the liquid crystal is changed. Then, the transmittance of light whose polarization state is controlled by the polarizing plate is changed.

    In general, the latter is slower when the applied electric field is increased to change the direction of the liquid crystal (director) and when the applied electric field is weakened and the direction of the liquid crystal (director) is changed by the viscoelasticity of the liquid crystal. . Therefore, in the case of a so-called normally white structure that displays white when no electric field is applied, the change from white level (gradation level 100%) to black level (gradation level 0%) (the applied electric field is strengthened). The change from the black level to the white level (change that weakens the applied electric field) is slower than (change). In addition, in the case of a structure that displays black when no electric field is applied, that is, a so-called normally black structure, a change from a black level to a white level (a change that increases the applied electric field) to a change from a white level to a black level (applied electric field) Change is weaker).

    As described above, the above feature [5] is due to the fact that the response characteristic of the liquid crystal varies depending on the applied electric field. In addition, this feature causes the following problems. In other words, the video quality when changing from a dark image to a bright image is particularly poor in the case of a normally white structure, and the video quality when changing from a bright image to a dark image is particularly bad in the case of a normally black structure. Especially worse.

    Next, a malfunction phenomenon caused by the above feature will be described.

    The feature [1] means that the liquid crystal display device that displays an image using the liquid crystal display element has a problem that the quality of the moving image is deteriorated.

    Furthermore, the feature [1] has a problem that in the FSC system, there is a problem that the gradation reproducibility is deteriorated or the chromatic color is deviated from the original color. It means that there is.

    Hereinafter, the problem in the FSC system that the gradation reproducibility is deteriorated will be specifically described by taking a liquid crystal display element having a normally white structure as an example.

    When displaying a single blue color on a certain pixel, the gradation level set for that pixel in field R is set to 0%, the gradation level set for that pixel is set to 0% in field G, and the pixel is set in field B to that pixel. The gradation level to be set is 100%. A characteristic curve EX1 shown in FIG. 1 is an LCD (Liquid Crystal Display) relative transmittance with respect to time when a single blue color is displayed on the same pixel. Here, it is assumed that gradation data is set for the pixel at the timing of field switching.

    The “LCD relative transmittance” here is a relative value of the light transmittance of the liquid crystal display element, and the gradation level is set to 100% (drive so that the gradation level becomes 100%). It is a relative value when the light transmittance is 100% when the liquid crystal responds sufficiently and the state is stabilized.

    When a cyan color, which is a mixed color of green and blue, is displayed on a certain pixel, the gradation level set for that pixel in field R is 0%, and the gradation level set for that pixel in field G is 100%. And the gradation level set for the pixel in field B is 100%. A characteristic curve EX2 shown in FIG. 2 shows an LCD with respect to time when red is displayed on the same pixel at a gradation level of 0% and then green and blue are sequentially displayed at a gradation level of 100%. Relative transmittance. Here, it is assumed that gradation data is set for the pixel at the timing of field switching.

    For example, even when the set gradation level of the constituent primary color B (blue) is the same 100%, at the end of the field B, the LCD relative transmittance (characteristics) when the displayed color is blue as shown in FIG. The value of the point a) of the curve EX1 and the LCD relative transmittance (point b of the characteristic curve EX2) when the displayed color is cyan as shown in FIG. 2 are different from each other. That is, even when the same gradation level is set, the brightness varies depending on the color to be displayed. That is, the gradation reproducibility is deteriorated.

    This malfunction phenomenon is caused by the feature [1] and the fact that the history of the state change of the liquid crystal orientation (director) differs depending on the color displayed in the FSC system. Note that this inconvenience can occur even in a still image.

    Further, in normally white, when the gradation changes from the white level (gradation level 100%) to the black level (gradation level 0%) due to the feature [5], the gradation level changes from the black level to the white level. Since the transmittance response is slower, the display of the primary color becomes dark.

    On the other hand, in normally black, the transmittance response is slower when the gradation is changed from the black level to the white level due to the feature [5]. When an image of a complementary color (for example, blue) (yellow in this example) is displayed, the constituent primary color component (blue in this example) does not become darker. In other words, it becomes a whitish color.

    Next, it will be described that the reproducibility of chromatic colors is deteriorated in the FSC system. Similar to the above-described problem of poor tone reproducibility, the phenomenon that the color of the chromatic color shifts is also caused by the characteristic [1] and the state change of the liquid crystal orientation (director) depending on the color displayed in the FSC system. This is because the history is different. That is, the state of the liquid crystal director in one field affects the relative transmittance of the LCD in the next field, thereby shifting the chromatic color. Note that this inconvenience can occur even in a still image.

    For example, when the cyan color is displayed as shown in FIG. 2, the set gradation level of both the constituent primary color G (green) and the constituent primary color B (blue) is 100%, but the end of the field G The LCD relative transmittance at the time point (point c of the characteristic curve EX2) and the LCD relative transmittance at the end time of the field B (point b of the characteristic curve EX2) are different from each other. This is because the LCD relative transmittance in the field G is affected by the state of the liquid crystal director in the field R in which the set gradation level is 0%, and the LCD relative transmittance in the field B is 100% in the set gradation level. This is because it is affected by the state of the liquid crystal director in the field G.

    In the example of FIG. 2, which is a case of normally white, the G color (green) is displayed darker than the original cyan color. In this way, since the balance between the G color and the B color is deviated from the original, the color is deviated. That is, the chromatic color reproducibility is deteriorated.

    In addition, the FSC system has a problem that the colors are different between the upper part and the lower part of the same display screen depending on the features [1] to [4].

    In the following, regarding the problem in the FSC system in which the colors are different between the upper part and the lower part of the same display screen, a liquid crystal display element having a normally white structure will be described as an example. explain.

    Depending on the features [1] to [3], the timing for outputting the image data designating the gradation level to the liquid crystal display element differs depending on the position in the screen constituted by the liquid crystal display element. Therefore, the phase at which the LCD relative transmittance starts to change varies depending on the position in the screen. Further, according to the feature [4], the light of the same color is simultaneously illuminated on all the pixels of the liquid crystal display element. Therefore, as in the region R3 for the characteristic curve EX3 and the region R4 for the characteristic curve EX4 shown in FIG. 3, the area (brightness) of each region depends on the phase at which image data is displayed on the pixel (that is, the position in the screen). There is a problem that they are different. In addition, in the case of the FSC system, when displaying an image of the same color with uniform gradation, the color differs depending on the position in the screen.

    Further, the liquid crystal display device works to hold the display until the image data is updated (in the FSC system, it works to hold the display of the previous field until the display of the image of the next field is started). Display device. The hold-type display device is said to have a lower moving image quality than an impulse-type display device (for example, CRT (Cathode Ray Tube)) in which the pixel is allowed to emit light in comparison with the cycle of updating the image data.

    As one method for improving the moving image quality in such a hold-type display device, it is known to shorten the image data update cycle.

    However, the features [1] to [4] cause a problem that the difference in gradation reproducibility corresponding to each position in the screen increases as the image data update cycle is shortened.

As above
In the FSC system, a problem occurs in the gradation reproducibility of a single primary color.

    In the FSC system, the chromatic color tone deviates from the original color.

    With normally white, there is a problem with the video quality when changing from displaying a dark image with a low gradation level to displaying a bright image with a high gradation level. With normally black, There is a problem with the video quality when changing to a dark image.

    In the FSC system, the colors are different between the upper part and the lower part of the same display screen.

    When the update cycle of image data is shortened in order to improve the moving image quality, there is a problem in that the difference in gradation reproducibility corresponding to each position in the screen increases accordingly.

    An object of the present invention is to provide a drive circuit, an image display apparatus, and a drive method that solve the above-described problems.

In order to solve the above problems, a driving circuit according to the present invention is used in an FSC image display device that forms one frame image by field images of a plurality of different colors, and displays the field image. A driving circuit that outputs a driving signal to the liquid crystal display element, and includes a gradation control unit that displays an image having a uniform gradation for a predetermined period when the field image is displayed on the liquid crystal display element ,
The gradation control means includes
An initialization data generation unit for generating initialization data indicating an image having a uniform gradation;
A selection unit that drives the liquid crystal display element by a signal in which the initialization data generated by the initialization data generation unit is inserted with respect to the supplied video signal indicating the field image;
The liquid crystal display element has a plurality of pixels arranged in a row direction and a column direction so as to form a lattice, and each of the pixels has a row direction arranged in the row direction for selecting the pixels. And connected to a line in the column direction arranged in the column direction for transmitting the signal output from the selection unit,
The selection unit outputs the initialization data to a pixel connected to a number of rows in a row direction, which is larger than the number of rows in a row direction selected when the video signal is simultaneously output to the pixel in a certain period. Output simultaneously,
The selection unit selects a pixel connected to the line in the row direction, which is selected in the slow order when outputting the video signal, and a pixel connected to the line in the row direction, which is selected earlier. It is characterized in that initialization data of a gradation that outputs an electric field smaller than the applied electric field is output .

In order to solve the above-described problems, an image display device according to the present invention is an FSC image display device that forms one frame image with a plurality of different color field images, and displays the field image. And a gradation control means for displaying an image having a uniform gradation for a predetermined period when displaying the field image on the display means ,
The gradation control means includes
An initialization data generation unit for generating initialization data indicating an image having a uniform gradation;
A selection unit that drives the display unit with a signal in which the initialization data generated by the initialization data generation unit is inserted with respect to the supplied video signal indicating the field image;
The display means has a plurality of pixels arranged in a row direction and a column direction so as to form a lattice, and each of the pixels has a row direction arranged in the row direction for selecting the pixel. Connected to a line and connected to a line in a row direction arranged in the column direction for transmitting a signal output from the selection unit,
The selection unit outputs the initialization data to a pixel connected to a number of rows in a row direction, which is larger than the number of rows in a row direction selected when the video signal is simultaneously output to the pixel in a certain period. Output simultaneously,
The selection unit selects a pixel connected to the line in the row direction, which is selected in the slow order when outputting the video signal, and a pixel connected to the line in the row direction, which is selected earlier. It is characterized in that initialization data of a gradation that outputs an electric field smaller than the applied electric field is output .

In order to solve the above-described problem, the driving method of the present invention provides a liquid crystal display element for displaying the field image included in the FSC image display device that forms one frame image by a plurality of different color field images. A driving method for outputting a driving signal, comprising: a gradation control process for displaying an image having a uniform gradation for a predetermined period when the field image is displayed on the liquid crystal display element ;
In the gradation control process,
Initialization data generation processing for generating initialization data indicating an image having a uniform gradation;
A selection process for driving the liquid crystal display element with a signal in which the initialization data generated in the initialization data generation process is inserted is performed on the supplied video signal indicating the field image,
The liquid crystal display element has a plurality of pixels arranged in a row direction and a column direction so as to form a lattice, and each of the pixels has a row direction arranged in the row direction for selecting the pixels. And connected to a line in the column direction arranged in the column direction for transmitting the signal output from the selection unit,
In the selection process, the initialization data is transferred to pixels connected to a larger number of row-direction lines than the number of row-direction lines selected when the video signal is simultaneously output to the pixels in a certain period. Output simultaneously,
In the selection process, when outputting the video signal, the pixel selected to be connected to the line in the row direction whose order is selected later is changed to the pixel connected to the line in the row direction whose order is selected earlier. It is characterized in that initialization data of a gradation that outputs an electric field smaller than the applied electric field is output .

    According to the present invention, an image having a uniform gradation is displayed on the liquid crystal display element before switching the field for updating the image data.

    With such a configuration, the influence of the state of the liquid crystal display element before the update of the image data on the state of the liquid crystal display element when displaying the image data (that is, the history dependency of the liquid crystal display element) can be reduced, As a result, the video quality can be improved.

It is a figure which shows the characteristic with respect to the elapsed time of LCD relative transmittance | permeability in a specific 1 pixel at the time of displaying a blue image on the general liquid crystal display device of a FSC system. It is a figure which shows the characteristic with respect to the elapsed time of LCD relative transmittance | permeability in a specific 1 pixel at the time of displaying a cyan image on the general liquid crystal display device of a FSC system. When a cyan image is displayed on a general liquid crystal display device of the FSC system, the LCD relative transmittance in each of the pixel to which the transferred image data is applied first and the pixel to which the transferred image data is applied last It is a figure which shows the characteristic with respect to elapsed time. It is a figure which shows the structure of the liquid crystal display device of Embodiment 1 of this invention. It is a figure which shows the structure of a liquid crystal display element. In Embodiment 1, it is a figure which shows an example of the gradation level designated as initialization data with respect to the pixel of a liquid crystal display element. In Embodiment 1, it is a figure which shows the characteristic of LCD relative transmittance | permeability in each of the pixel which applies the transferred image data first, and the pixel which applies the transferred image data last. In Embodiment 2, it is a figure which shows an example of the gradation level designated as initialization data with respect to the pixel of a liquid crystal display element. In Embodiment 2, it is a figure which shows the characteristic of LCD relative transmittance | permeability in each of the pixel which applies the transferred image data first, and the pixel which applies the transferred image data last. It is a figure which shows the structure of the liquid crystal display device of Embodiment 3 of this invention. In Embodiment 3, it is a figure which shows an example of the gradation level designated as initialization data with respect to the pixel of a liquid crystal display element.

(Embodiment 1)
Hereinafter, an image display device (including a driving circuit and a driving method) according to the first embodiment of the present invention will be described.

    Hereinafter, the case where the image display device of the present invention is the FSC liquid crystal display device 1 will be described as an example. However, the image display device of the present invention can be applied to any FSC system display device that forms a single frame image with field images of a plurality of different colors.

    First, the configuration of the liquid crystal display device 1 of Embodiment 1 will be described.

    As shown in FIG. 4, the present liquid crystal display device 1 includes a control unit 111, a data processing unit 11, a liquid crystal display element 12 that is a “display unit”, and an illumination unit 13.

    The liquid crystal display device 1 may be of a direct view type in which an image is directly displayed by light modulated by the liquid crystal display element 12. The light modulated by the liquid crystal display element 12 is screened (not shown) through a projection optical system (not shown). Projection type that displays images by projecting to (). Further, when the liquid crystal display device 1 is a projection type, it may be a front projection type having a projection optical system (not shown), or a rear projection having a projection optical system (not shown) and a screen (not shown). It may be a mold.

    The control unit 111 receives a timing signal indicating the synchronization timing of the input frame (hereinafter referred to as “input frame synchronization timing”), and generates a timing signal indicating the synchronization timing of the output frame (hereinafter referred to as “output frame synchronization timing”). . Further, a timing signal indicating the output field synchronization timing (hereinafter referred to as “output field synchronization timing”) obtained by dividing one frame period of output into three color field periods is generated. In addition, the control unit 111 converts the timing signal into the data rearrangement unit 112, the initialization data generation unit 113, the selection unit 114, the VT characteristic correction unit 115, the liquid crystal display element 12, and the illumination unit 13. Output to.

    Hereinafter, the start timing of the output frame period is the timing at which the gradation data of the image in that frame is first applied to the liquid crystal display element. The start timing of the output field period of each color is set to the timing at which the gradation data of the corresponding color of the image in the corresponding frame is first applied to the liquid crystal display element.

    In the present embodiment, the input frame synchronization timing and the output field synchronization timing are synchronized, but they may be asynchronous. Note that these timing signals are not specifically described. Since the operation timing will be described in the operation description to be described later, it should be easily understood by those skilled in the art.

    The data processing unit 11 includes a data rearrangement unit 112, an initialization data generation unit 113, a selection unit 114, and a VT characteristic correction unit 115. The initialization data generation unit 113 and the selection unit 114 constitute “gradation control means”.

    The data rearrangement unit 112 receives two systems of timing signals (a timing signal indicating an input frame synchronization timing and a timing signal indicating an output field synchronization timing) from the control unit 111.

    The data rearrangement unit 112 includes a memory control unit 112a and a frame memory 112b.

    The memory control unit 112a accepts a plurality of video signals corresponding to a plurality of colors on a one-to-one basis for each input frame synchronization timing by a timing signal from the control unit 111. In the present embodiment, the memory control unit 112a includes, as a plurality of video signals, an R color video signal (video signal (R)) corresponding to red and a G color video signal (video signal (G)) corresponding to green. The B color video signal (video signal (B)) corresponding to blue is received and the image data of each color is written in the frame memory 112b.

    The plurality of video signals each include image data VDATA for displaying an arbitrary image. Here, “image data VDATA” refers to data indicating the gradation level LVV set for each pixel of the liquid crystal display element 12 in each field (field R, field G, or field B).

    In addition, the memory control unit 112a performs the arrangement of the R color image data, the G color image data, and the B color image data on the frame memory 112b at each output frame synchronization timing in accordance with the timing signal from the control unit 111. The signals are read one by one in order and output to the VT characteristic correction unit 115 as an R color video signal, a G color video signal, and a B color video signal, respectively.

    The frame memory 112b is used as a buffer for rearranging a plurality of video signals. The rearrangement of the plurality of video signals is performed by differently controlling the memory address when writing the image data of each color into the memory and when reading it out from the memory.

    The initialization data generation unit 113 generates “initialization data INT”. Then, the initialization data generation unit 113 outputs the initialization data INT to the selection unit 114 at every output field synchronization timing in accordance with the timing signal from the control unit 111.

    “Initialization data INT” is image data with substantially uniform gradation applied before the original image data VDATA is applied to the liquid crystal display element 12. Hereinafter, the initialization gradation level, which is the gradation level indicated by the initialization data INT, will be expressed as a symbol “LVI”. Hereinafter, setting the gradation level LVI indicated by the initialization data INT to each pixel is referred to as “initialization”.

    In the first embodiment, the initialization data generation unit 113 generates initialization data INT indicating an initialization gradation level LVI set in advance to a fixed value.

    The liquid crystal display element 12 may be either normally white or normally black. Hereinafter, the case of normally white will be described as an example.

    The gradation level LVI for initialization is that the LCD relative transmittance (that is, the state of the liquid crystal orientation) of the liquid crystal display element 12 when the image of the previous field is displayed is the liquid crystal when the image of the next field is displayed. It is set to reduce the influence of the display element 12 on the LCD relative transmittance (that is, the state of the liquid crystal orientation). Therefore, the initialization gradation level LVI has an electric field with a value smaller than the gradation level at which the electric field applied to the pixel is maximum (for example, the gradation level 0% which is a black level in normally white). It is desirable that the gradation corresponds to the application. This is from the viewpoint of avoiding a start state in which the transmittance response is the slowest when displaying a gray scale different from the gray scale currently displayed by the pixel.

    In the example of the first embodiment, the initialization data generation unit 113 generates initialization data INT in which the initialization gradation level LVI is set to “60%” for all the pixels in the liquid crystal display element 12.

    As will be described later in Embodiment 3, the initialization data generation unit 113 may generate initialization data INT based on a plurality of video signals input from the outside.

    The selection unit 114 alternately selects the image data VDATA and the initialization data INT in the video signal corresponding to the color of each field for each output field synchronization timing according to the timing signal from the control unit 111, and the image data VDATA or initialization data INT is output to the liquid crystal display element 12 as an LCD drive signal.

    Note that the data line driving circuit and the scanning line driving circuit provided in the liquid crystal display element 12 set the gradation level LVV or the initialization gradation level LVI to each pixel.

    When the video signal of each color is input, the VT characteristic correction unit 115 applies the pixel to the pixel based on the VT characteristic representing the relationship between the applied voltage (drive voltage) in the liquid crystal display element 12 and the relative LCD transmittance of light. The image data in the video signal is corrected so as to adjust the applied voltage. The correction method of the VT characteristic of the liquid crystal display element 12 may be a general method.

    The VT characteristic correction unit 115 also corrects the R color video signal, the G color video signal, and the B color video signal corrected based on the VT characteristic at each output field synchronization timing by the timing signal from the control unit 111. Are output to the selection unit 114 one by one in the arrangement order.

    In order to prevent deterioration (burn-in) that occurs when the electric field applied to the liquid crystal of the liquid crystal display element 12 is not zero in terms of time average, a general method may be used to reverse the polarity of the applied electric field.

    The illumination unit 13 includes an R color LED light source 13-R including an LED that emits light of R color (red), a G color LED light source 13-G that includes an LED that emits light of G color (green), and a B color ( It has a B-color LED light source 13-B including an LED emitting blue light.

    The illuminating unit 13 changes the R color LED light source 13-R, the G color LED light source 13-G, and the B color LED light source 13-B at every output field synchronization timing according to the timing signal from the control unit 111. Light up one by one in order. Note that the timing (period and phase) at which the illumination unit 13 irradiates light is a response of light transmittance after the image data VDATA indicating the original gradation level LVV is output to the liquid crystal display element 12 as an LCD drive signal. It is adjusted considering the degree.

    The light output from the illumination unit 13 illuminates the liquid crystal display element 12. Since the liquid crystal display element 12 controls the light transmittance for each pixel in accordance with the image data VDATA, an image is displayed when the illumination unit 13 illuminates the light. Therefore, the image display device 1 operates as follows.

    When the liquid crystal display element 12 forms an image corresponding to the R color video signal, the illumination unit 13 turns on the R color LED light source 13-R and irradiates the liquid crystal display element 12 with R color light. Thereafter, when the liquid crystal display element 12 forms an image corresponding to the G color video signal, the illumination unit 13 lights the G color LED light source 13-G and irradiates the liquid crystal display element 12 with the G color light. To do. Thereafter, when the liquid crystal display element 12 forms an image corresponding to the B color video signal, the illumination unit 13 turns on the B color LED light source 13-B and irradiates the liquid crystal display element 12 with the B color light. To do.

    The plurality of colors are not limited to the R color, the G color, and the B color, and may be arbitrary. For example, cyan, magenta, and yellow may be used. Further, the number of the plurality of colors may be four or more. For example, in addition to the R color, the G color, and the B color, white or yellow may be included. In order to control white and yellow light, for example, the illumination unit 13 may be individually controlled with a white LED light source and a yellow LED light source, or the illumination unit 13 may be an R-color LED light source or G color. When an LED light source and a B color LED light source are provided, white light may be turned on simultaneously with RGB, or yellow light may be turned on simultaneously with RG. The order of the plurality of colors is R, G, and B, but other orders may be used.

    The liquid crystal display element 12 receives an LCD drive signal containing image data having gradation level information of each pixel from the selection unit 114 of the data processing unit 11, and receives a timing signal (LCD control signal) from the control unit 111. ). Then, a predetermined gradation level is set for each pixel by these signals. That is, a voltage corresponding to a predetermined gradation level is applied to each pixel electrode (not shown) by these signals. As a result, an electric field corresponding to a predetermined gradation level is applied to the liquid crystal of each pixel.

    As shown in FIG. 5, the liquid crystal display element 12 includes a plurality of pixels, a plurality of data lines, a plurality of scanning lines, a data line driving circuit, and a scanning line driving circuit.

    The plurality of pixels in the liquid crystal display element 12 are arranged in the X direction (column direction) and the Y direction (row direction) so as to form a lattice. Each pixel extends in the Y direction (row direction) and is connected to one of a plurality of signal lines (data lines) in the X direction (column direction), and extends in the X direction to have a plurality of signal lines (scanning lines) in the Y direction. Is connected with either. The data line can be generally referred to as a “column-direction line”. Further, the scanning line can be generally referred to as a “line in the row direction”.

    The scanning line driving circuit inputs a timing signal (LCD control signal) from the control unit 111 and drives each scanning line. The scanning line driving circuit selects each scanning line in order according to the LCD control signal.

    The data line driving circuit receives a timing signal (LCD control signal) from the control unit 111 and an LCD driving signal from the selection unit 114, and drives each data line. The data line driving circuit sequentially selects each data line according to the LCD control signal and supplies a voltage corresponding to a predetermined gradation level according to the LCD driving signal to the selected data line. Then, a voltage corresponding to a predetermined gradation level is supplied from the selected data line to the pixels connected to the selected scanning line.

    When the liquid crystal display element 12 receives the LCD drive signal from the selection unit 114, a voltage corresponding to the gradation level LVV or the initialization gradation level LVI is supplied to each pixel, and an electric field is applied to the liquid crystal disposed in each pixel. Applied. As a result, the direction (director) of the liquid crystal is controlled for each pixel, and the light transmittance changes according to the direction (director) of the liquid crystal for each pixel. In this way, the liquid crystal display element 12 modulates the light emitted from the illumination unit 13 and displays an image. Further, in the case of the FSC system, image data of a color corresponding to each color field is applied to the liquid crystal display element 12, and light of a corresponding color is irradiated from the illumination unit 13 to the liquid crystal display element 12 in synchronization therewith. Thus, a color image is displayed.

    In the present embodiment, the scanning line driving circuit can simultaneously select two or more scanning lines from all the scanning lines shown in FIG. In the initialization period, that is, the period in which the initialization data INT is selected by the selection unit 114, the initialization data is simultaneously transmitted from the data line selected by the data line driver circuit to the pixels connected to the two or more selected scanning lines. An initialization gradation level LVI indicated by INT is set. By doing so, the initialization period can be shortened. In the present embodiment, as shown in FIG. 6, an initialization gradation level LVI preset to a fixed value (for example, 60%) is set in an image display area formed by all pixels of the liquid crystal display element 12. It is set uniformly.

    A method for simultaneously outputting the initialization data INT to a plurality of signal lines is not particularly limited.

    For example, a known method for shortening the data transfer time in the vertical direction (Y direction) as disclosed in JP-A-2006-163358 can be used. In this case, during the initialization period, first, the scanning line driving circuit detects the odd-numbered specific scanning line (for example, the first scanning line) and the even-numbered row immediately below the specific scanning line. One scanning line of the eye (for example, the scanning line in the second row) is selected at the same time. Then, simultaneously with the pixels connected to the two selected scanning lines, the initialization gradation level LVI indicated by the initialization data INT is set from the data line selected by the data line driving circuit. The scanning line driving circuit includes the following odd-numbered one scanning line (for example, the third scanning line) and the even-numbered first scanning line (for example, the fourth scanning line) immediately below the scanning line. Are simultaneously selected, and the above-described procedure is repeated to apply the initial gradation level to all pixels. By doing so, the initialization period can be shortened.

    Also, for example, a known method for shortening the data transfer time in the horizontal direction (X direction) as disclosed in Japanese Patent Application Laid-Open No. 2007-171567 can be used. In this case, in the initialization period, that is, in the period in which the initialization gradation level LVI is set in the pixel, the data line driving circuit has more data lines than in the case where the image gradation level LVV is set in the pixel. A voltage corresponding to the gradation level LVI for initialization is simultaneously supplied to the plurality of selected data lines at the same time. By doing so, the initialization period can be shortened.

    By the method as described above, in the present invention, the time difference between the time when the initialization data INT is first output to the pixel and the time when the initialization data INT is last output to the pixel is reduced. Thereby, the time difference at which the transmittance of each pixel in the liquid crystal display element 12 starts to change is reduced. Therefore, when displaying a field image, the difference in color according to the position in the screen can be reduced.

    Next, the liquid crystal display device 1 according to the first embodiment having the above-described configuration performs an operation of alternately selecting the image data VDATA and the initialization data INT and outputting them as LCD drive signals to each pixel of the liquid crystal display element 12. This will be described with reference to FIG.

    In this example, the liquid crystal display device 1 displays a cyan frame image in which G color and B color are mixed. That is, the gradation level LVV indicated by the R color video signal is 0%, the gradation level LVV indicated by the G color video signal is 100%, and the gradation level LVV indicated by the B color video signal is 100%.

    First, when the control unit 111 inputs a timing signal indicating the input frame synchronization timing of the frame FR-1 shown in FIG. 7, each output of the field R, field G, and field B obtained by dividing one frame FR-1 into three. A timing signal indicating field synchronization timing is generated.

    Further, the memory control unit 112a of the data rearrangement unit 112 corresponds to the R color video signal corresponding to red and the green color in synchronization with the input frame synchronization timing of the frame FR-1 by the timing signal from the control unit 111. The G color video signal and the B color video signal corresponding to blue are received and written to the frame memory 112b.

    Thereafter, the memory control unit 112 a reads out the R color video signal on the frame memory 112 b in synchronization with the output frame synchronization timing by the timing signal from the control unit 111, and outputs it to the VT characteristic correction unit 115.

    When the R color video signal from the memory control unit 112a is input, the VT characteristic correction unit 115 adjusts the voltage applied to the pixel based on the VT characteristic in the liquid crystal display element 12. Correct the image data. Further, the VT characteristic correction unit 115 outputs the R color video signal corrected based on the VT characteristic to the selection unit 114 in synchronization with the output field synchronization timing by the timing signal from the control unit 111.

    When the selection unit 114 selects the R color video signal from the VT characteristic correction unit 115 in synchronization with the output field synchronization timing by the timing signal from the control unit 111, the selection unit 114 converts the R color video signal into the LCD drive signal. To the liquid crystal display element 12.

    Note that in the R color image data transfer period of the field R, the scanning line driving circuit selects one scanning line at a time, and the data line driving circuit applies to each pixel of one row connected to the selected scanning line. The image data VDATA indicating the gradation level LVV (0%) included in the R color video signal is transferred. Since the application of the gradation level LVV (0%) here is a case where the electric field applied to the liquid crystal is strengthened, the LCD relative transmittance of each pixel is a predetermined value (see FIG. 5) in the order in which the gradation level LVV is applied. In the example of FIG. 7, it quickly changes to 0%).

    Thereafter, the illumination unit 13 turns on the R-color LED light source 13-R in synchronization with the output field synchronization timing by the timing signal from the control unit 111. That is, when the liquid crystal display element 12 forms an image corresponding to the R color video signal, the illumination unit 13 turns on the R color LED light source 13-R and irradiates the liquid crystal display element 12 with R color light. To do.

    On the other hand, the initialization data generation unit 113 generates the initialization data INT indicating the initialization gradation level LVI in advance. In the first embodiment, the gradation level LVI for initialization is preset to 60%. Then, the initialization data generation unit 113 outputs the initialization data INT to the selection unit 114 in synchronization with the output field synchronization timing based on the timing signal from the control unit 111.

    When the selection unit 114 selects the initialization data INT from the initialization data generation unit 113 in synchronization with the output field synchronization timing in accordance with the timing signal from the control unit 111, the selection unit 114 uses the initialization data INT as the LCD drive signal. Output to the display element 12.

    Then, in the initialization data transfer period, the scanning line driving circuit and the data line driving circuit set the initialization gradation level LVI indicated by the initialization data INT in each pixel of the liquid crystal display element 12. In the present embodiment, the scanning line driving circuit is configured to scan, from all the scanning lines, a specific one scanning line on the odd-numbered row (for example, the first row) and one scanning on the even-numbered row immediately below the specific scanning line. A line (for example, the second row) is selected at the same time. Then, simultaneously with the pixels connected to the two selected scanning lines, the initialization gradation level LVI indicated by the initialization data INT is set from the data line selected by the data line driving circuit. The scanning line driving circuit simultaneously selects the next odd-numbered one scanning line (for example, the third line) and the even-numbered first scanning line (for example, the fourth line) immediately below the scanning line. The above procedure is repeated to apply the initial gradation level to all the pixels. By doing so, the initialization period is shortened.

    Then, the LCD relative transmittance of each pixel of the liquid crystal display element 12 corresponds to the R gradation level LVV (0%) in the order in which the initialization data INT indicating the initialization gradation level LVI is output. It starts to change from LCD relative transmittance (0%).

    Here, attention is focused on the waveform of the LCD relative transmittance of the pixel to which the image data VDATA shown in FIG. 7 is transferred last.

    With respect to this pixel, since the gradation level LVV (= 0%) of the field R is set, the LCD relative transmittance is 0% at the timing when the R color LED light source 13-R is turned on. Further, an initialization gradation level LVI (= 60%) is set for this pixel shortly before the end of the field R, and the applied electric field is weakened. Therefore, as the time for the liquid crystal of the pixel for which the gradation level LVI is set last to respond, the time for almost one field from when the gradation level LVI is set until the G color LED light source 13-G is turned on. It is secured.

    On the other hand, the waveform of the LCD relative transmittance in the pixel to which the image data is applied last when the cyan image is displayed on the general liquid crystal display device of the FSC system illustrated in FIG. 3 is referred again. In the example of FIG. 3, the applied electric field is weakened after the LCD relative transmittance of this pixel has changed to 0% in the field R. The gray level is applied to this pixel at the end of the image data transfer period of the field G. (100%) is set. Therefore, in the example of FIG. 3, the G color LED light source is turned on without securing a sufficient response time for the liquid crystal of the pixel whose gradation level is set last, as in the example of FIG.

    As described above, in the liquid crystal display device 1 according to the present invention, the image data VDATA is caused by the time difference between the time when the non-zero gradation level is first set after the relative transmittance becomes zero and the time when the LED light source is turned on. As a result, the time required for the last applied pixel for the liquid crystal response is secured, and as a result, the gradation reproducibility can be improved.

    The detailed explanation of the operation in the field G is as follows. Among the operations in the field R described above, the video signal read from the frame memory 112b by the memory control unit 112a is read from “R color video signal” to “G color video signal”. “R color image data transfer period” is read as “G color image data transfer period of field G”, and “gradation level LVV (0%) included in R color video signal” is “floor included in G color video signal”. By replacing “tone level LVV (100%)”, “R color LED light source 13-R” with “G color LED light source 13-G”, and “R color light” with “G color light” It can be carried out.

    In the field G, the applied electric field to the liquid crystal of each pixel is weakened for each order in which the image data VDATA indicating the gradation level LVV (100%) is applied, so that the LCD relative transmittance of each pixel further increases. To do.

    Thereafter, in the field G, the LCD relative transmittance of each pixel further increases in the order in which the initialization data INT indicating the gradation level LVI is applied. Note that, as described above, in the present embodiment, the gradation level LVI (60%) that is not zero is applied to each pixel in the field R and the gradation level LVI is applied to each pixel in the field G. 1 field is reserved.

    The detailed description of the operation in the field B is as follows. Among the operations in the field R described above, the video signal read out from the frame memory 112b by the memory control unit 112a is changed from “R color video signal” to “B color video signal”. “R color image data transfer period of field R” is read as “B color image data transfer period of field B”, and “gradation level LVV (0%) included in R color video signal” is included in “B color video signal included To “Gray level LVV (100%)”, “R color LED light source 13-R” to “B color LED light source 13-B”, and “R color light” to “B color light” Can be done.

    In the field B, the LCD relative transmittance of each pixel further increases in every order in which the gradation level LVV (= 100%) indicated by the image data VDATA included in the B color video signal is set. In this embodiment, when the transfer of the image data VDATA of the field B is completed and the LCD relative transmittance of each pixel is maximum, the B-color LED light source 13-B irradiates each pixel.

    Thereafter, in the field B, the LCD relative transmittance of each pixel changes to a predetermined value (60% in the example of FIG. 7) in every order in which the LCD drive signal of the initialization gradation level LVI is output.

    The liquid crystal display device 1 repeatedly performs the above-described operation for each frame period. Thus, the operation of the liquid crystal display device 1 according to the first embodiment alternately selecting the image data VDATA and the initialization data INT and outputting it as an LCD drive signal to each pixel of the liquid crystal display element 12 is completed.

    As described above, according to the first embodiment of the present invention, before the liquid crystal display element 12 displays the image of the next field, the LCD relative transmittance of each pixel in the liquid crystal display element 12 starts to change. Advance the phase in advance. That is, the influence of the liquid crystal state before the update of the image data VDATA on the liquid crystal state when the image data VDATA is displayed (history dependence of the liquid crystal state) can be reduced, and the moving image quality can be improved.

    Thereby, in normally white, when the gradation level LVV set in the liquid crystal display element 12 changes from a low black level to a high white level, the effect of improving the liquid crystal response start phase is particularly great.

    Further, according to the first embodiment, even when the largest electric field is applied to each pixel in the gradation setting for each pixel in a certain color field, the gradation level of initialization is performed in that color field. LVI (eg, 60%) is set and the applied electric field is weakened. Therefore, it is possible to secure a time for the liquid crystal of each pixel to respond until the gradation level LVV of the original image data VDATA is set for each pixel and illuminated in the next field, and the gradation of the primary color in the FSC system is secured. Reproducibility and chromatic color reproducibility can be improved. In particular, a great improvement effect is obtained with respect to the gradation reproducibility of the pixel whose gradation level LVV is set last.

    According to the first embodiment, when transferring the initialization data INT, the scanning line driving circuit simultaneously selects a plurality of scanning lines, and the data line driving circuit simultaneously initializes the initialization data INT to the plurality of selected scanning lines. Apply. As a result, the difference in timing at which each pixel starts the liquid crystal response can be further reduced, and as a result, the difference in color reproducibility and gradation reproducibility according to the position (for example, upper and lower) in the display screen can be improved. It becomes possible.

Furthermore, according to the first embodiment, in the field period immediately before the next field, the LCD drive signal of the initialization gradation level LVI is output to the liquid crystal display element 12 in advance, so that the liquid crystal state is turned to the intermediate state. Keep it changing. Therefore, the change in the liquid crystal state can be accelerated on average prior to the update of the field image.
(Embodiment 2)
Next, the liquid crystal display device 1 of Embodiment 2 will be described.

    In the second embodiment, the difference in the liquid crystal response phase between the pixels having different positions in the screen, which is caused by the timing difference in which the image data VDATA is applied to each pixel of the liquid crystal display element 12, is further reduced as compared with the first embodiment.

    Therefore, the liquid crystal display device 1 according to the second embodiment displays an image display area including all pixels of the liquid crystal display element 12 in relation to the order (timing) of transferring the image data VDATA indicating the gradation level LVV. 8 is divided into a plurality of areas, and relative to pixels in an area where the order (timing) in which the image data VDATA indicating the gradation level LVV is applied is slow and the LCD relative transmittance is delayed and changes are started. Therefore, an initial gradation level LVI having a higher gradation corresponding to applying a small electric field is set.

    In the example of FIG. 8, the image display area is divided into five areas (A = 1 to 5) in the Y direction (see FIG. 5) according to the order of the scanning lines. For each color field period, image data is first applied to all pixels in the area A = 1, then image data is applied to all pixels in the area A = 2, and thereafter A = 3. Next, image data is applied to the area A, the area A = 4, and the area A = 5.

    In the liquid crystal display device 1 according to the second embodiment, in the configuration illustrated in FIG. 4, the initialization data generation unit 113 has a fixed value set in advance so as to be different for each area of A = 1 to 5 in the liquid crystal display element 12. Initialization data INT indicating the gradation level LVI of initialization represented by Expression 2 is generated with K (A). However, Formula 1 shall be materialized.

また、初期化データ生成部１１３は、制御部１１１からのタイミング信号によって出力フィールド同期タイミングごとに、エリアごとに異なる階調レベルＬＶＩを示す初期化データＩＮＴを、画像データＶＤＡＴＡが各エリアに出力される順番と同じ順番で、選択部１１４へ出力する。

The initialization data generation unit 113 outputs initialization data INT indicating different gradation levels LVI for each area and image data VDATA to each area for each output field synchronization timing in accordance with a timing signal from the control unit 111. To the selection unit 114 in the same order as

    In the present embodiment, as illustrated in FIG. 8, the initialization data generation unit 113 performs the initialization gradation level for each pixel belonging to the area of A = 1 where the image data VDATA is output first. Set LVI to "50%".

    The initialization data generation unit 113 sets the initialization gradation level LVI to “70%” for each pixel belonging to the area of A = 5 where the image data VDATA is output last.

    In the present embodiment, the gradation level LVI (50%) set for the area A = 1 and the gradation level LVI (70%) set for the area A = 5 are set. By performing linear interpolation, the gradation level LVI for the pixels belonging to each area of A = 2 to 4 is calculated. That is, it calculates by the above-mentioned formula 2 and the following formula 3.

しかし、Ａ＝２〜４の各エリアに属する画素に適用する階調レベルＬＶＩは、これらのうち画像データＶＤＡＴＡが先に適用される画素に適用する階調レベルＬＶＩよりも、画像データＶＤＡＴＡが後から適用される画素に適用する階調レベルＬＶＩが大きくなるようであれば、線形補間以外にも任意の方法を用いて算出可能である。例えば、初期化データ生成部１１３は、非線形補間を用いてＡ＝２〜４の各エリアに属する画素に適用する階調レベルＬＶＩを算出してもよく、演算またはＬＵＴ（Look-up Table）により階調レベルＬＶＩを算出してもよい。

However, the gradation level LVI applied to the pixels belonging to each area of A = 2 to 4 is the image data VDATA later than the gradation level LVI applied to the pixels to which the image data VDATA is applied first. As long as the gradation level LVI to be applied to the pixels to be applied increases, it can be calculated using any method other than linear interpolation. For example, the initialization data generation unit 113 may calculate the gradation level LVI to be applied to the pixels belonging to each area of A = 2 to 4 by using non-linear interpolation, and by calculation or LUT (Look-up Table). The gradation level LVI may be calculated.

    The selection unit 114 receives initialization data INT indicating different gradation levels LVI for each area of A = 1 to 5 within the initialization period at an output field synchronization timing according to a timing signal from the control unit 111. As a drive signal, the image data VDATA is output to the liquid crystal display element 12 in the same order as the order of outputting to each area.

    The liquid crystal display element 12 inputs the initialization data INT from the selection unit 114 as an LCD drive signal in the same order as the output order of the image data VDATA, and receives a timing signal (LCD control signal) from the control unit 111. . Then, in the initialization data transfer period of each color field, the scanning line driving circuit firstly, in the area of A = 1, from among all scanning lines in the area, a specific scanning line on the odd row and immediately below it. Are selected simultaneously with the even-numbered one scanning line. Then, simultaneously to the pixels connected to the two selected scanning lines, from the data line selected by the data line driving circuit, the initialization gradation level LVI determined for the area of A = 1 (in this example, 50%) Set. The scanning line driving circuit simultaneously selects the odd-numbered one scanning line that follows and the even-numbered one scanning line immediately below the scanning line driving circuit, repeats the above-described procedure, and sets the initialization gradation level LVI. Applies to all pixels in the area of A = 1.

    Subsequently, the scanning line driving circuit and the data line driving circuit respectively perform the same operation as the area of A = 1 for each area of A = 2, 3, 4 and 5, and the initialization levels different for each area. The tone level LVI is applied to all the pixels in each area of A = 2 to 5, respectively.

    Next, the operation of the liquid crystal display device 1 of Embodiment 2 will be described with reference to FIG. In this example, the liquid crystal display device 1 displays a cyan frame image in which G color and B color are mixed.

    In the operation of the second embodiment, the initialization data generation unit 113 performs initialization as shown as an initialization gradation level LVI set in advance to a fixed value different for each area of A = 1 to 5 as illustrated in FIG. The point in which the digitized data INT is generated in advance is different from the operation of the first embodiment.

    In the operation of the second embodiment, the selection unit 114 uses, as an LCD drive signal, initialization data INT indicating different gradation levels LVI for each area in the initialization data transfer period at each output field synchronization timing. The point of outputting to the liquid crystal display element 12 in the same order that the image data VDATA is output to the area is different from the operation of the first embodiment.

    The initialization data generation unit 113 uses the timing signal from the control unit 111 to synchronize with the output field synchronization timing, and the initialization data indicating different gradation levels LVI for each area in the initialization data transfer period of each color field. INT is output to the selection unit 114 in the same order as the order in which the image data VDATA is output to each area. In the present embodiment, the initialization data generation unit 113 sends the initialization data INT indicating the gradation level LVI corresponding to each area of A = 1, 2, 3, 4, 5 to the selection unit 114 in that order. Output.

    Then, the selection unit 114 converts the initialization data INT from the initialization data generation unit 113 into the LCD drive signal in the initialization data transfer period shown in FIG. 9 at each output field synchronization timing by the timing signal from the control unit 111. Are output to the liquid crystal display element 12 in each order of A = 1, 2, 3, 4, 5 in that order.

    The liquid crystal display element 12 inputs the initialization data INT as an LCD drive signal one by one in the order output from the selection unit 114, and inputs a timing signal (LCD control signal) from the control unit 111. Then, the scanning line driving circuit and the data line driving circuit sequentially apply LCD driving signals having different gradation levels LVI for each area to each pixel belonging to each area of A = 1, 2, 3, 4 and 5. Go.

    As an example of this application operation, the liquid crystal display element 12 inputs a timing signal (LCD control signal) indicating the output field synchronization timing of the field R from the control unit 111 in one frame FR-1 shown in FIG. I will explain.

    In this case, in the initialization data transfer period of the field R, the liquid crystal display element 12 first selects the initialization data INT indicating the gradation level LVI set to a fixed value (50%) for the area of A = 1. Input from the unit 114. The scanning line driving circuit and the data line driving circuit output initialization data INT indicating 50% as the gradation level LVI to each pixel in the area of A = 1 as an LCD driving signal.

    In the present embodiment, in the area of A = 1, the scanning line driving circuit generates a specific odd-numbered scanning line and an even-numbered scanning line immediately below it from all the scanning lines in the area. Select simultaneously. Then, simultaneously to the pixels connected to the two selected scanning lines, from the data line selected by the data line driving circuit, the initialization gradation level LVI determined for the area of A = 1 (in this example, 50%) Set. The scanning line driving circuit simultaneously selects the odd-numbered one scanning line that follows and the even-numbered one scanning line immediately below the scanning line driving circuit, repeats the above-described procedure, and sets the initialization gradation level LVI. Applies to all pixels in the area of A = 1.

    Then, in the order in which the gradation level LVI for initialization for A = 1 is applied, the LCD relative transmittance of each pixel belonging to the area of A = 1 corresponds to the gradation level LVV (0%) of R color. It starts to change from LCD relative transmittance (0%).

    Subsequently, the liquid crystal display element 12 selects initialization data INT indicating the gradation level LVI set to a fixed value (55%) for the area of A = 2 during the initialization data transfer period of the field R. Enter from. Then, the scanning line driving circuit and the data line driving circuit output initialization data INT indicating 55% as the gradation level LVI to each pixel in the area of A = 2 as an LCD driving signal. Note that the operation in which the scanning line driving circuit and the data line driving circuit apply the gradation level LVI indicated by the initialization data INT to each pixel in the area A = 2 is the same as the operation described for the area A = 1. It is.

    Then, in the order in which the initialization gradation level LVI for A = 2 is applied, the LCD relative transmittance of each pixel belonging to the area of A = 2 corresponds to the gradation level LVV (0%) of the R color. It starts to change from LCD relative transmittance (0%).

    Thereafter, the scanning line driving circuit and the data line driving circuit also have gradations set to different fixed values for each area of A = 3, 4, 5 in the order of the areas of A = 3, 4, 5 as well. Initialization data INT indicating the level LVI is output as an LCD drive signal.

    In this case, an electric field smaller than the electric field applied to the pixels belonging to the area where the initialization data INT is output first is applied to the pixels belonging to the area where the initialization data INT is output later. For this reason, even if the LCD relative transmittance of the pixel to which the initialization data INT is output later is changed later than the LCD relative transmittance of the pixel to which the initialization data INT is output earlier, it is output later. The LCD relative transmittance of the pixel can be made closer to the LCD relative transmittance of the pixel whose LCD has started to change first.

    That is, according to the second embodiment, the image data VDATA is reduced in order to reduce the difference in the LCD relative transmittance between the pixels having different in-screen positions caused by the timing difference in which the image data VDATA is applied to each pixel of the liquid crystal display element 12. The gradation level LVI corresponding to the weakening of the applied electric field is applied to the pixel to be transferred later than the pixel to which the gradation level LVV is transferred earlier.

Thereby, a difference in gradation and a difference in color according to the position in the screen where the pixels for displaying the image are arranged can be reduced.
(Embodiment 3)
Next, the liquid crystal display device 1 of Embodiment 3 will be described.

    In the FSC system, the history of the state change of the liquid crystal orientation (director) in each color field differs depending on the color to be displayed, and the gradation and color vary depending on the position in the screen.

    Therefore, in the third embodiment, the initialization gradation level LVI for each area is determined based on the gradation level LVV of the video applied to the pixels in each area.

    First, the configuration of the liquid crystal display device 1 of Embodiment 3 will be described with reference to FIG.

    As illustrated in FIG. 10, the initialization data generation unit 113 according to the third embodiment inputs two timing signals (a timing signal indicating an input frame synchronization timing and a timing signal indicating an output field synchronization timing) from the control unit 111. Then, the R color video signal, the G color video signal, and the B color video signal are input in synchronization with the input frame synchronization timing by the timing signal.

    The initialization data generation unit 113 receives the R color image signal of the R color video signal, the G color image data of the G color video signal, Based on each of the B color image data of the B color video signal, a predetermined calculation value CALC (A) is calculated for each area of A = 1 to 5 in the color field corresponding to each color.

    Then, the initialization data generation unit 113 calculates F (A) by substituting the calculated value CALC (A) into the relational expression exemplified in the following Expression 4.

本実施形態では、式４におけるＫ（Ａ）は、上述の式３に示したＫ（Ａ）と同じである。Ｋ（Ａ）は、画像データＶＤＡＴＡを各エリアに適用するタイミング差と、各エリアの画素間のＬＣＤ相対透過率の差異とを考慮して調整してもよい。

In this embodiment, K (A) in Equation 4 is the same as K (A) shown in Equation 3 above. K (A) may be adjusted in consideration of a timing difference in which the image data VDATA is applied to each area and a difference in LCD relative transmittance between pixels in each area.

    Further, the constants C and D in Expression 4 are individually adjusted and set in advance in the liquid crystal display device 1. In this embodiment, it is set in advance to a fixed value of C = 1.5, and is set in advance to a fixed value of D = 30%.

    When the initialization data generation unit 113 calculates F (A) using Equation 4, the initialization gradation level LVI for each area of A = 1 to 5 is calculated based on F (A) and Equation 5 below. [%] Is determined, and initialization data INT indicating the gradation level LVI is generated.

つまり、初期化データ生成部１１３は、算出したＦ（Ａ）と、１００とを比較して、比較の結果、Ｆ（Ａ）が１００以下である場合、そのＦ（Ａ）を、初期化の階調レベルＬＶＩとして決定する。また、初期化データ生成部１１３は、比較の結果、Ｆ（Ａ）が１００よりも大きい場合、固定値である１００［％］を、初期化の階調レベルＬＶＩとして決定する。

That is, the initialization data generation unit 113 compares the calculated F (A) with 100, and if F (A) is 100 or less as a result of the comparison, the initialization data generation unit 113 converts the F (A) into the initialization data. The gradation level LVI is determined. Further, when F (A) is larger than 100 as a result of comparison, the initialization data generation unit 113 determines 100 [%], which is a fixed value, as the initialization gradation level LVI.

    In this embodiment, the initialization data generation unit 113 receives the R color image signal of the R color video signal, the G color video signal each time the R color video signal, the G color video signal, or the B color video signal is input. Based on the G color image data or the B color image data of the B color video signal, the average value AVR (A) within the area of the gradation level LVV of the image in each area for each color field corresponding to each color is calculated. Calculated as the value CALC (A).

    That is, in the present embodiment, the initialization data generation unit 113 calculates F (A) using the following Expression 6 in which the average value AVR (A) is substituted into Expression 4 as the calculated value CALC (A).

そして、初期化データ生成部１１３は、Ｆ（Ａ）と式５とに基づいて各エリアの初期化の階調レベルＬＶＩ［％］を決定して、階調レベルＬＶＩを示す初期化データＩＮＴを生成する。このように入力フレーム同期タイミングに同期して求められた初期化データＩＮＴは、初期化データ生成部１１３におけるバッファ（図示せず）に保持される。

Then, the initialization data generation unit 113 determines the initialization gradation level LVI [%] of each area based on F (A) and Equation 5, and sets initialization data INT indicating the gradation level LVI. Generate. Thus, the initialization data INT obtained in synchronization with the input frame synchronization timing is held in a buffer (not shown) in the initialization data generation unit 113.

    Then, the initialization data generation unit 113 converts the initialization data INT indicating the gradation level LVI for each area in each color field into the R color, the G color, and the output field synchronization timing according to the timing signal from the control unit 111. The data is output from the buffer to the selection unit 114 in the order of B color. When the initialization data INT is output in each color field, the initialization data generating unit 113 initializes the initialization data indicating the gradation level LVI corresponding to each area of A = 1, 2, 3, 4, 5. INT is output to the selection unit 114 in that order.

    Next, in accordance with the average value AVR (A) of the gradation level LVV set in the pixels for each area of A = 1 to 5, the gradation level for initialization of each area is obtained by the linear calculation and clamping described above. An example in which the LVI is specifically determined will be described with reference to FIG.

    When the average value AVR (1) = 20% of the gradation level LVV set in the area of A = 1 in the specific one color field calculated by the initialization data generation unit 113 for the area of A = 1 think of.

    When the initialization data generation unit 113 calculates the average value AVR (1) of the area of A = 1, the initialization data generation unit 113 calculates F (1) using the average value AVR (1) and Expression 6. Note that K (A) in Equation 6 is obtained by substituting A = 1 into Equation 3 as K (1) = 0.5. Therefore, the initialization data generation unit 113 calculates F (1) = AVR (1) × K (1) × C + D = 20 × 0.5 × 1.5 + 30 = 45 as F (1).

    Subsequently, the initialization data generation unit 113 compares the calculated F (1) = 45 with 100. In this case, F (1) is 100 or less. Therefore, the initialization data generation unit 113 determines F (1) = 45 as an initialization gradation level LVI [%] to be applied to the area of A = 1 based on Equation 5.

    That is, as shown in FIG. 11, in correspondence with the case where the average value AVR (1) = 20% of the image data in the area A = 1, the gradation level of initialization applied to the area A = 1. LVI is determined to be 45%.

    Further, consider a case where the average value AVR (1) of the area of A = 1 calculated by the initialization data generation unit 113 is 80%.

    The initialization data generation unit 113 calculates F (1) corresponding to the average value AVR (1) = 80% by Expression 6. In this case, the initialization data generation unit 113 calculates F (1) = 80 × 0.5 × 1.5 + 30 = 90 as F (1). Subsequently, the initialization data generation unit 113 compares the calculated F (1) = 90 with 100. In this case, since F (1) is 100 or less, the initialization data generation unit 113 sets F (1) = 90 to the gradation level LVI for initialization for the area of A = 1 based on Equation 5. Determine as.

    That is, as shown in FIG. 11, in correspondence with the case where the average value AVR (1) = 80% of the image data in the area A = 1, the gradation level of initialization applied to the area A = 1. LVI is determined to be 90%.

    Also, consider a case where the average value AVR (5) = 20% of A = 5 in a specific color field calculated by the initialization data generation unit 113 for the area of A = 5.

    The initialization data generation unit 113 calculates F (5) corresponding to the average value AVR (5) = 20% using Expression 6. Note that K (A) in Equation 6 is obtained by substituting A = 5 into Equation 3 as K (5) = 0.7. In this case, the initialization data generation unit 113 calculates F (5) = AVR (5) × K (5) × C + D = 20 × 0.7 × 1.5 + 30 = 51 as F (5).

    Subsequently, the initialization data generation unit 113 compares the calculated F (5) = 51 with 100. In this case, since F (5) is 100 or less, the initialization data generation unit 113 sets F (5) = 51 based on Expression 5 to the gradation level LVI for initialization for the area of A = 5. Determine as. That is, as shown in FIG. 11, the gradation level of initialization applied to the area of A = 5 corresponding to the case where the average value AVR (5) of the image data in the area of A = 5 = 20%. LVI is determined to be 51%.

    Further, consider a case where the average value AVR (5) of the area of A = 5 calculated by the initialization data generation unit 113 is 80%.

    The initialization data generation unit 113 calculates F (5) corresponding to the average value AVR (5) = 80% by Expression 6. In this case, the initialization data generation unit 113 calculates F (5) = 80 × 0.7 × 1.5 + 30 = 114 as F (5). Subsequently, the initialization data generation unit 113 compares the calculated F (5) = 114 with 100. In this case, since F (5) is larger than 100, the initialization data generation unit 113 determines 100 [%] as the initialization gradation level LVI for the area of A = 5 based on Expression 5. . That is, as shown in FIG. 11, in correspondence with the case where the average value AVR (5) of image data in the area A = 5 = 80%, the gradation level of initialization applied to the area A = 5 LVI is determined to be 100%.

    Then, the initialization data generation unit 113 generates initialization data INT indicating the determined gradation level LVI of each area.

    Then, the initialization data generation unit 113 converts the initialization data INT indicating the gradation level LVI for each area in each color field into the R color, the G color, and the output field synchronization timing according to the timing signal from the control unit 111. The data is output to the selection unit 114 in the order of B color. When the initialization data INT is output in each color field, the initialization data generating unit 113 initializes the initialization data indicating the gradation level LVI corresponding to each area of A = 1, 2, 3, 4, 5. INT is output to the selection unit 114 in that order.

    The selection unit 114 outputs initialization data INT indicating the gradation level LVI for each area to each area as an LCD drive signal in the initialization data transfer period at each output field synchronization timing in accordance with the timing signal from the control unit 111. Are output to the liquid crystal display element 12 in the same order as the output order of the image data VDATA.

    The liquid crystal display element 12 inputs the initialization data INT as an LCD drive signal one by one in the order output from the selection unit 114, and inputs a timing signal (LCD control signal) from the control unit 111. Then, the scanning line driving circuit and the data line driving circuit perform the same operation as the application operation described above in the second embodiment, so that the LCD driving signal of the gradation level LVI corresponding to each area is A = 1, This is sequentially applied to each pixel belonging to each of the areas 2, 3, 4 and 5.

    Note that the value used as the calculated value CALC (A) shown in Expression 4 is not particularly limited.

    For example, the calculated value CALC (A) may be the maximum value of the image gradation level LVV for each area, or may be the average value of gradation levels belonging to the top 10% in the frequency distribution for the image gradation level. These values are calculated values CALC (A) that place importance on gradation levels that are slower in response than the average value AVR (A) in each area.

    Therefore, when the gradation level LVI for initialization of each area is determined using these values as the calculation value CALC (A), a high gradation level LVV is set for some pixels in a certain area (small). Even if it is necessary to apply an electric field, the gradation level LVI for initialization becomes larger and the effect of weakening the applied electric field is further enhanced. For this reason, the effect of improving the gradation level of the portion with poor gradation reproducibility in the screen is further enhanced.

    As described above, according to the third embodiment, the initialization gradation level applied to each area according to the predetermined calculation value CALC (A) of the gradation level LVV set for the pixels belonging to each area. Adjust LVI. This reduces a difference in LCD relative transmittance between pixels with different positions in the screen caused by a difference in timing when the image data VDATA is applied to each pixel of the liquid crystal display element 12, and further reduces a specific position in the screen (for example, It is also possible to reduce the history dependence of the liquid crystal response of each pixel in a specific area.

    As mentioned above, although this invention was demonstrated with reference to Embodiment 1-3, this invention is not limited to the said Embodiment 1-3. Various modifications that can be understood by those skilled in the art can be made to the configuration and details of the present invention without departing from the gist of the present invention.

Claims (9)

A driving circuit for outputting a driving signal to a liquid crystal display element that is used in an FSC image display device that forms one frame image from a plurality of different color field images;
When the field image is displayed on the liquid crystal display element, the image display device includes gradation control means for displaying an image having a uniform gradation for a predetermined period ,
The gradation control means includes
An initialization data generation unit for generating initialization data indicating an image having a uniform gradation;
A selection unit that drives the liquid crystal display element by a signal in which the initialization data generated by the initialization data generation unit is inserted with respect to the supplied video signal indicating the field image;
The liquid crystal display element has a plurality of pixels arranged in a row direction and a column direction so as to form a lattice, and each of the pixels has a row direction arranged in the row direction for selecting the pixels. And connected to a line in the column direction arranged in the column direction for transmitting the signal output from the selection unit,
The selection unit outputs the initialization data to a pixel connected to a number of rows in a row direction, which is larger than the number of rows in a row direction selected when the video signal is simultaneously output to the pixel in a certain period. Output simultaneously,
The selection unit selects a pixel connected to the line in the row direction, which is selected in the slow order when outputting the video signal, and a pixel connected to the line in the row direction, which is selected earlier. A drive circuit which outputs initialization data of a gradation that applies an electric field smaller than an applied electric field . The drive circuit according to claim 1 ,
The selection unit includes pixels included in each area of initialization data of gradations determined according to a calculated value of gradation of the video signal for each of a plurality of areas each including a part of the plurality of pixels. A drive circuit characterized by output to The drive circuit according to claim 1 or 2 ,
The initialization data generation unit generates initialization data of a gradation corresponding to applying an electric field having a value smaller than a gradation at which an electric field applied to the pixel is maximum among gradations of the video signal. A drive circuit characterized by that. An FSC image display device that forms one frame image with a plurality of different color field images,
Display means for displaying the field image;
A gradation control means for displaying an image having a uniform gradation for a predetermined period when the field image is displayed on the display means ;
The gradation control means includes
An initialization data generation unit for generating initialization data indicating an image having a uniform gradation;
A selection unit that drives the display unit with a signal in which the initialization data generated by the initialization data generation unit is inserted with respect to the supplied video signal indicating the field image;
The display means has a plurality of pixels arranged in a row direction and a column direction so as to form a lattice, and each of the pixels has a row direction arranged in the row direction for selecting the pixel. Connected to a line and connected to a line in a row direction arranged in the column direction for transmitting a signal output from the selection unit,
The selection unit outputs the initialization data to a pixel connected to a number of rows in a row direction, which is larger than the number of rows in a row direction selected when the video signal is simultaneously output to the pixel in a certain period. Output simultaneously,
The selection unit selects a pixel connected to the line in the row direction, which is selected in the slow order when outputting the video signal, and a pixel connected to the line in the row direction, which is selected earlier. An image display device that outputs initialization data having a gradation that applies an electric field smaller than an applied electric field . The image display device according to claim 4 ,
The selection unit includes pixels included in each area of initialization data of gradations determined according to a calculated value of gradation of the video signal for each of a plurality of areas each including a part of the plurality of pixels. An image display device characterized by output to The image display device according to claim 4 or 5 ,
The initialization data generation unit generates initialization data of a gradation corresponding to applying an electric field having a value smaller than a gradation at which an electric field applied to the pixel is maximum among gradations of the video signal. An image display device characterized by that. A driving method for outputting a driving signal to a liquid crystal display element that displays the field image provided in an FSC image display device that forms one frame image with a plurality of different color field images,
A gradation control process for displaying an image having a uniform gradation for a predetermined period when the field image is displayed on the liquid crystal display element ;
In the gradation control process,
Initialization data generation processing for generating initialization data indicating an image having a uniform gradation;
A selection process for driving the liquid crystal display element with a signal in which the initialization data generated in the initialization data generation process is inserted is performed on the supplied video signal indicating the field image,
The liquid crystal display element has a plurality of pixels arranged in a row direction and a column direction so as to form a lattice, and each of the pixels has a row direction arranged in the row direction for selecting the pixels. And connected to a line in the column direction arranged in the column direction for transmitting the signal output from the selection unit,
In the selection process, the initialization data is transferred to pixels connected to a larger number of row-direction lines than the number of row-direction lines selected when the video signal is simultaneously output to the pixels in a certain period. Output simultaneously,
In the selection process, when outputting the video signal, the pixel selected to be connected to the line in the row direction whose order is selected later is changed to the pixel connected to the line in the row direction whose order is selected earlier. A driving method characterized by outputting initialization data of a gradation that applies an electric field smaller than an applied electric field . The driving method according to claim 7 ,
In the selection process, the initialization data of the gradation determined according to the calculated value of the gradation of the video signal for each of the plurality of areas each including a part of the plurality of pixels is included in each of the areas. A driving method comprising: The driving method according to claim 7 or 8 ,
In the initialization data generating process, initialization data having a gradation corresponding to applying an electric field having a value smaller than a gradation at which the electric field applied to the pixel is maximum among the gradations of the video signal is generated. A driving method characterized by that.

Images