JP2009042315A - Liquid crystal display and television receiving device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display capable of attaining image display of high contrast without incurring complication of a driving circuit. <P>SOLUTION: The liquid crystal display 10 is provided with a panel for area display (dimming panel) 1 having a liquid crystal display panel changing transmittance of light from a backlight unit 3 matching an image displayed on a panel 2 for image display between the panel 2 for image display having a liquid crystal display panel divided into an image display area 21 and a non-display area 22 and performing image display in the image display area and the backlight unit (light source) 3 radiating light to the panel 2 for image display. The panel 1 for area display has a plurality of pixel electrodes 11 (11a to 11f) having shapes which are made coincident with shapes of the image display area 21 of the panel 2 for image display, and pixel electrodes transmitting light from the backlight and pixel electrodes transmitting no light from the backlight are determined matching the shapes of the image display area 21. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device and a television receiver in which contrast is improved by using a light control liquid crystal panel.

  In recent years, flat panel displays have become popular in the market as large and thin display devices. As flat panel displays become familiar, it is desired to improve their display performance.

  Since a liquid crystal display device as one type of flat panel display does not emit light by itself, it has a liquid crystal panel that controls image display and a backlight that illuminates the liquid crystal panel. In such a liquid crystal display device, the backlight is always turned on, and the amount of transmitted light is controlled by a liquid crystal panel placed on the light emission side of the backlight.

  Usually, polarizing plates are arranged on the front and back surfaces of the liquid crystal panel, respectively, and linearly polarized light that has passed through the polarizing plate on the incident side of the light emitted from the backlight is modulated for each pixel by the liquid crystal panel, and on the outgoing side. Analyzing with polarizing plate. In this case, the display quality of black display is determined by how efficiently light is absorbed by the two polarizing plates arranged on the front and back of the liquid crystal panel.

  However, since the backlight is always on, even if the liquid crystal panel displays black, the liquid crystal orientation in the liquid crystal panel is disturbed, the refractive index difference between the films, and the scattering by the color filter pigment. Due to various causes such as the limit of optical compensation, the light that does not sufficiently satisfy the crossed Nicols condition that can be formed by the polarizing plates on the incident side and the outgoing side is somewhat lost from the polarizing plate on the outgoing side.

  This leakage light is observed when the screen is displayed in black in a dark room, because the screen is floating in gray, and this is a factor that reduces the contrast (the difference in the amount of light between the white display and the black display). This is one of the challenges to high quality images of the device.

For example, Patent Documents 1 and 2 provide a backlight unit that uses an LED as a light source, and each of them is dimmed in accordance with the corresponding image area to improve display quality. Yes.
JP 2002-99250 (April 5, 2002) JP 2002-91385 (released March 27, 2002)

  However, in the dimming with the backlight using the LED as a light source as described above, the light emitting point may be close to point light emission, and a large number of LEDs must be spread to obtain the required luminance. This increases the complexity of the backlight drive circuit and the cost.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a liquid crystal display device and a television receiver capable of realizing high-contrast image display without causing a complicated drive circuit. And

  In order to solve the above problems, a liquid crystal display device according to the present invention has a liquid crystal display panel, and is divided into an image display area and a non-display area in the liquid crystal display panel, and the image display area displays an image. In a liquid crystal display device comprising an image display panel for performing light and a light source for irradiating the image display panel with light, the liquid crystal display panel is provided between the image display panel and the light source, and the image A light control panel that changes the transmittance of light from the light source in accordance with an image displayed on the display panel is provided, and the light control panel has a shape of the image display area in the image display panel. A plurality of pixel electrodes having a shape matching that of the pixel electrode, and a pixel electrode that transmits light from the light source according to the shape of the image display area, and does not transmit light from the light source It is characterized in that the pixel electrodes are determined.

  In the liquid crystal display device of the present invention, a light control panel capable of changing the transmittance of light from the light source according to the image displayed on the image display panel is provided between the image display panel and the light source. Has been placed. And the shape of the pixel electrode provided in the said light control panel corresponds with the shape of the image display area in the image display panel.

  According to the above configuration, since the pixel electrode of the light control panel is formed according to the shape of the image display area in the image display panel, the light control panel corresponds to the predetermined image display area. Dimming can be performed using the pixel electrode. That is, when an image is displayed in a specific image display area, a bright image is displayed on the corresponding pixel electrode of the dimming panel (that is, the light transmittance is increased), thereby making the image display area brighter. Can be displayed. Further, since the pixel electrode of the light control panel is formed in accordance with the shape of the image display area in the image display panel, light is not transmitted from the corresponding pixel electrode of the light control panel in the non-display area. In this way, the light from the backlight can be prevented from leaking from the light control panel, and the display can be made darker.

  Therefore, according to the present invention, a high contrast display can be realized without using a complicated circuit such as a backlight control circuit.

  The liquid crystal display device of the present invention displays an image in a panel such as an in-vehicle liquid crystal display panel equipped with a car navigation system, an information liquid crystal display panel in which an area for presenting information is predetermined, and the like. The present invention can be suitably used for a liquid crystal display panel in which an area and a non-display area are clearly divided into relatively large sections.

  In the liquid crystal display device of the present invention, the image display panel has a plurality of display states having different shapes of the image display area, and matches the shape of the image display area in each of the plurality of display states. In addition, it is preferable that a pixel electrode that transmits light from the light source among the pixel electrodes provided on the light control panel is determined.

  According to said structure, when an image display panel is each display state, light control can be performed with the pixel electrode of a light control panel with respect to each image display area. In addition, an area that is an image display area in the first display state and a non-display area in the second display state is displayed by changing the transmittance of the pixel electrode in the corresponding area on the dimming panel. The light can be adjusted according to the image. That is, a bright display can be realized in the first display state, and a more sunk black display can be achieved in the second display state.

  In the liquid crystal display device of the present invention, it is preferable that the light control panel is provided with a drive unit that changes a gradation value of an image displayed on each of the pixel electrodes.

  According to the above configuration, the dimming panel can perform, for example, gradation display from black to white by changing the voltage applied to the pixel electrode by the drive circuit as described above, and the image It is possible to display with different gradations for each display area. Therefore, more detailed gradation expression can be performed by using two panels of an image display panel and a dimming panel, and the display quality can be further improved.

  A television receiver according to the present invention includes a tuner unit that receives a television broadcast, and a liquid crystal display device that displays the television broadcast received by the tuner unit. It is characterized by being a liquid crystal display device.

  Since the television receiver of the present invention includes the above-described liquid crystal display device, an image display with high contrast and improved display quality can be realized.

  As described above, the liquid crystal display device according to the present invention has a liquid crystal display panel between the image display panel and the light source. From the light source according to the image displayed on the image display panel. The light control panel has a plurality of pixel electrodes having a shape that matches the shape of the image display area in the image display panel. According to the shape of the image display area, a pixel electrode that transmits light from the light source and a pixel electrode that does not transmit light from the light source are determined.

  Therefore, according to the present invention, a high contrast display can be realized without using a complicated circuit such as a backlight control circuit.

  An embodiment of the present invention will be described below with reference to FIGS. Note that the present invention is not limited to this.

  In this embodiment, a liquid crystal display device in which an image display area and a non-display area are clearly divided into relatively large sections in a panel such as an in-vehicle liquid crystal display panel or an information display will be described as an example. . However, the present invention is not limited to this.

  In the liquid crystal display device 10 according to the present embodiment, as shown in FIG. 1, an area display panel (light control panel) 1 is disposed between an image display panel 2 and a backlight unit (light source) 3. This is the structure. In FIG. 1, an optical film such as a scattering plate 41 provided between the image display panel 2 and the area display panel 1 and a light diffusion plate provided in the backlight unit 3 is illustrated. Omitted.

  The area display panel 1 is composed of a liquid crystal display panel, and a plurality of pixel electrodes 11 (11a to 11f) having different shapes are provided on the panel surface. As a result, the area display panel 1 varies the transmittance of the light emitted from the backlight unit 3 according to the image displayed on the image display panel 2, depending on the pixel electrodes 11 (11 a to 11 f). be able to. The pixel electrodes 11 (11a to 11f) transmit light from the backlight unit 3 or block light from the backlight unit 3 in accordance with the shape of the image display area in the image display panel 2. is doing.

  The image display panel 2 is a liquid crystal display panel having an image display surface (also referred to as an internal region) 2a in which a plurality of pixels (not shown) are arranged in a matrix. That is, the liquid crystal display panel constituting the image display panel 2 is a so-called active matrix liquid crystal display panel in which switching elements such as TFT elements are provided for a plurality of pixels arranged in a matrix. is there.

  The backlight unit 3 uses a plurality of fluorescent lamps as light sources, a surface facing the area display panel 1 and the image display panel 2 as a light emission surface 3a, and the area display panel 1 and the image display from the light emission surface 3a. Light is directed toward the panel 2 for use.

  FIG. 2 is a cross-sectional view showing a more specific configuration of the liquid crystal display device 10.

  As shown in FIG. 2, the area display panel 1 is located between the image display panel 2 and the backlight unit 3. The area display panel 1 has a liquid crystal layer 14 sandwiched between two substrates 101a and 101b. The polarizing plate 15 on the backlight unit 3 side and the polarizing plate on the light incident side of the image display panel 2 ( In the present embodiment, the polarizing plate 25a) has a panel configuration capable of gray scale display.

  The image display panel 2 includes a liquid crystal layer 24 between glass substrates 201a and 201b, and includes a liquid crystal display panel in which a plurality of pixels (not shown) are arranged in a matrix. As the liquid crystal display panel constituting the image display panel 2, a liquid crystal display panel generally used as a display device can be used. Polarizing plates 25a and 25b having a crossed Nicols relationship are disposed on the outer sides of the glass substrates 201a and 201b.

  The display surface of the image display panel 2 is divided into an internal region 2a in which a plurality of pixels are arranged and an image is displayed, and a frame region 2b provided outside the internal region. Furthermore, the internal area 2a includes an image display area 21 where an image is actually displayed and a non-display area 22 where no image is displayed (that is, a black display state) (the shaded portion in FIG. 1). It is divided.

  The image display panel 2 according to the present embodiment includes, for example, an image display state (first display state) for displaying an image such as a television image or a car navigation display as shown in FIG. A plurality of display states in which the shape of the image display area differs depending on the case, such as an instrument display state (second display state) for displaying various instruments such as a speedometer and a fuel meter as shown in a). It is possible to switch with. FIG. 1 shows a state where a television image is displayed as an example of the display state.

  Further, the polarizing plate on the display surface side (the side opposite to the backlight unit 3 side) of the area display panel 1 can also serve as the polarizing plate 25 a of the image display panel 2. Therefore, in the present embodiment, as shown in FIG. 2, the polarizing plate on the display surface side of the area display panel is omitted. Here, the polarizing plate 15 of the area display panel 1 and the polarizing plate 25a on the back side (backlight unit 3 side) of the image display panel 2 have a crossed Nicols relationship.

  However, the present invention is not limited to the above configuration, and a polarizing plate may be further disposed between the area display panel 1 and the scattering plate 41. That is, the scattering plate 41 may be sandwiched between two polarizing plates. In this case, since the polarized light disturbed by the area display panel 1 can be absorbed, the contrast can be further improved.

  A scattering plate 41 is installed between the image display panel 2 and the area display panel 1. By scattering the light transmitted through the area display panel 1 by the scattering plate 41, the display boundary of the area display panel 1 (that is, the boundary of the pixel electrode 11) can be enhanced.

  The area display panel 1 and the image display panel 2 are preferably installed with a certain distance d, and the scattering plate 41 is preferably installed in contact with the image display panel 2. Thus, by arranging the area display panel 1 and the image display panel 2 with a predetermined interval therebetween, not only the effect of tanning by the scattering plate 41 disposed between the panels is further enhanced. There is a merit that a diffusion effect can be obtained while suppressing that the polarized light emitted from the area display panel 1 is disturbed by the scattering plate 41.

  The backlight unit 3 is a general backlight using a lamp 38 made of a fluorescent tube as a light source. Therefore, although the backlight unit 3 can adjust the light to some extent on the entire emission surface or for each fluorescent tube, it cannot be dimmed for each divided area by dividing the emission surface.

  Further, in order to divide the backlight unit 3 composed of fluorescent tubes into areas, it is necessary to provide fluorescent tubes for each area and make the mechanism capable of being turned on and off. .

  For example, when a fluorescent tube is arranged according to the shape of the area, the shape of the fluorescent tube itself is complicated. In addition, the area size is limited by the size of the fluorescent tube, and it is not possible to deal with a fine area. Furthermore, as the number of areas increases, the circuit for driving the fluorescent tube becomes complicated.

  However, in the present embodiment, since the gradation representation of each image display area is adjusted by the liquid crystal of the area display panel 1, the backlight unit 3 can be always in a lighting state. Therefore, there is no burden on the backlight unit 3 side composed of the fluorescent tube as described above, and the mechanism becomes simple.

  An optical film such as a scattering plate 37 and a prism sheet 36 is disposed on the surface of the backlight unit 3 (the surface facing the area display panel 1).

  In the liquid crystal display device 10 having the above configuration, a display image is expressed through two panels, an area display panel 1 and an image display panel 2. Thereby, the image display area can realize bright display by, for example, displaying the pixel electrode in the area display panel in white (transmitting light from the backlight unit 3), and the non-display area can be displayed in the area display. Both the display panel and the image display panel are displayed in black, and these black displays are combined to be expressed in black. In other words, in the black representation, the image display panel 2 is displayed using the leakage light when the area display panel 1 displays black (that is, light is not transmitted from the backlight unit 3) as the backlight. For this reason, it can be said that the display gradation width of the dark portion is widened.

  In other words, in the present invention, the white display on one image display panel 2 is maximized, the gradation expression in the dark direction spreads from here, and the black display becomes an expression through two black display states. The black display is blacker than the one display panel. For this reason, the image is tightened and the contrast is improved.

  Next, the structure of the area display panel 1 will be described in detail.

  FIG. 3 shows a planar structure of the area display panel 1. FIG. 3 shows pixels (pixel electrodes 11), signal wirings 16 and the like formed on the glass substrate 101a of the area display panel 1. FIG. 4 shows a cross-sectional structure taken along line X-X ′ of the area display panel 1 shown in FIG. 3.

  As shown in FIG. 3, the area display panel 1 corresponds to an inner area 1 a where pixel electrodes 11 (11 a to 11 f) of various shapes are arranged and an outer edge portion 1 b (a frame area of the image display panel 2). And a portion hatched in FIG. A drive driver (drive unit) 13 for driving each pixel electrode 11 is provided on the outer side of the outer edge 1b.

  In the internal region 1a, the pixel electrodes 11a to 11b formed in accordance with the shape of the image display area in the image display panel 2 are arranged so as to correspond to the image display areas.

  In the present invention, the image display panel corresponds to the image display area in each image display state when the display state can be switched between a plurality of display states having different shapes of the image display area. It is preferable that the shape of the pixel electrode is defined.

  Thereby, it is possible to perform light control by the area display panel in accordance with the image display area in each image display state, and it is possible to further improve the display quality.

  Therefore, in the area display panel 1 of the present embodiment, pixel electrodes 11a to 11f having various shapes as shown in FIG. 3 are formed.

  Further, as shown in FIG. 3, the outer edge portion 1b of the area display panel 1 is subjected to a light shielding process so that no excessive light wraps around the image display panel 2.

  In the present embodiment, the area display panel 1 employs a segment display method as its display method from the viewpoint of being able to express gradation and reducing the panel cost. In the segment display method, a signal wiring for driving is provided for each pixel. That is, as shown in FIG. 3, the signal wiring 16 is provided between all the pixel electrodes 11 a to 11 f and the driving driver 13. Then, by changing the voltage applied to each pixel electrode from the driver 13 for driving, gradation display from white to black can be performed on each pixel electrode 11a to 11f, and the luminance of the image can be adjusted. it can.

  The structure of the area display panel 1 will be described in more detail with reference to the cross-sectional view shown in FIG.

  The area display panel 1 has a configuration in which a liquid crystal layer 14 is sandwiched between substrates 101a and 101b. Here, since the substrates 101a and 101b may be transparent substrates, glass, plastic, a transparent resin film, or the like can be used as the material.

  A transparent electrode to be the pixel electrode 11 is formed on one of the two substrates 101a via the signal wiring 16 and the interlayer insulating layer 18, and the counter electrode 17 and the entire surface are formed on the other substrate 101b. A transparent electrode is formed. Then, after an alignment film (not shown) is formed on the surface of these transparent electrodes, the substrate 101a and the substrate 101b are arranged to face each other at a desired distance, and liquid crystal is sealed therebetween. In this way, the liquid crystal display panel constituting the area display panel 1 is formed.

  Below, the manufacturing method of the panel 1 for area display is demonstrated.

  As the substrate 101a, first, Al and Mo which are materials of the signal wiring 16 are successively formed in this order by sputtering on a glass substrate. The material of the signal wiring 16 is not limited to these, and Cu, Al alloy, or Cu alloy may be used instead of Al. Moreover, you may use refractory metals, such as Ti and Ta, instead of Mo. In order to use wet etching for low resistance and wiring formation, it is preferable to select Al and Mo as the material of the signal wiring and to set the film thickness to 3000 mm for Al and 1000 mm for Mo.

  Next, in order to process the formed metal film into wiring, a photoresist is applied and a wiring pattern is formed on the resist by photolithography. Thereafter, the Al and Mo films are wet-etched with an etching solution. After the etching process, the resist is removed to form the signal wiring 16. The width of each signal line 16 may be set to 100 μm, for example.

  A photosensitive acrylic resin is applied on the formed signal wiring 16 as an interlayer insulating layer 18 disposed between the pixel electrode 11. Then, contact holes are formed in the interlayer insulating layer 18 by photolithography.

  Next, an ITO film is formed on the interlayer insulating layer 18 of the substrate 101a as a transparent electrode to be the pixel electrode 11 by sputtering. The ITO film and the signal wiring 16 are connected through a contact hole formed in the interlayer insulating layer 18.

  After the sputtering film formation is performed on the ITO film, a resist is applied, and a resist pattern is formed in the shape of each pixel electrode by photolithography. Based on this resist pattern, the ITO film is processed by wet etching to form pixel electrodes 11 of various shapes.

  On the other substrate 101b, an ITO film as a transparent electrode is formed as a counter electrode 17 on the entire surface by sputtering.

  An alignment film (not shown) is further formed on the substrate 101a and the substrate 101b having the above structure. For example, the alignment film is formed by printing a polyimide film with a thickness of 500 mm. After that, rubbing or ultraviolet irradiation is performed as necessary to align the liquid crystal, and a sealing resin (not shown) is formed on the outer periphery of the panel and bonded to each substrate. Then, a liquid crystal material is injected between the substrates to display the area. Panel 1 is formed.

  In this embodiment, the liquid crystal is aligned vertically, and the gap between the upper and lower substrates is 5 μm. As a method for guaranteeing the distance between the two substrates, a method of spreading beads over the entire surface of the substrate can be used. However, in the present invention, the orientation of the liquid crystal panel used as the area display panel 1 is not limited to the vertical orientation, and may be other orientations.

  The area display panel 1 manufactured as described above is further provided with a driving driver 13. Here, an example is shown in which driving drivers 13 are arranged on the left and right sides, and each pixel 11 is driven from both the left and right sides. In the cross-sectional view of the area display panel 1 shown in FIG. 4, of the two substrates constituting the area display panel 1, the substrate 101 a on which the signal wiring is formed is a region where the driving driver 13 is mounted at the end. Each signal wiring 16 is formed so as to be connected to the driver terminal of the driving driver 13.

  Note that the arrangement of the signal wiring 16 to the pixel 11 is not limited to the example shown in FIGS.

  Subsequently, the image display panel 2 displays, for example, an image display state (first display state) in which an image such as a television image or a car navigation display as shown in FIG. 5A is displayed, and FIG. When switching between a plurality of display states in which the shape of the image display area is different from each other, such as an instrument display state (second display state) for displaying various instruments such as a speedometer and a fuel meter as shown in FIG. The display state of the area display panel 1 will be described.

  FIG. 5 is a diagram when the liquid crystal display device 10 is in the first display state. FIG. 5A is a diagram illustrating a display state of the image display panel 2, and FIG. 5B is a diagram illustrating a display state of the area display panel 1.

  FIG. 6 is a diagram when the liquid crystal display device 10 is in the second display state. FIG. 6A is a diagram showing a display state of the image display panel 2, and FIG. 6B is a diagram showing a display state of the area display panel 1.

  As shown in FIG. 5A, in the first display state, the image display panel 2 has three image display areas 21a, 21a, and 21a in the internal region 2a. At this time, in the area display panel 1, as shown in FIG. 5B, the pixel electrodes 11a, 11b, 11c, 11e, and 11f corresponding to the three image display areas 21a, 21a, and 21a are constant. The display is performed with the gradation value. That is, the light from the backlight is transmitted with various transmittances in the pixel electrodes 11a, 11b, 11c, 11e, and 11f corresponding to the image display area. On the other hand, the pixel electrode 11 d corresponding to the non-display area is displayed in black, and the light from the backlight unit 3 is shielded by the area display panel 1. That is, the light from the backlight is not transmitted through the pixel electrode 11d corresponding to the non-display area.

  Next, for example, when the display state is changed to the second display state by switching the screen, each instrument is displayed in the internal area 2a of the image display panel 2, so that as shown in FIG. The image display areas 21b, 21b, 21b, and 21b are formed. At this time, in the area display panel 1, as shown in FIG. 6B, the pixel electrodes 11b, 11c, 11d, and 11f corresponding to the four image display areas 21b, 21b, 21b, and 21b are constant. The display is performed with the gradation value. On the other hand, the pixel electrodes 11 a and 11 e corresponding to the non-display areas are displayed in black, and the light from the backlight unit 3 is blocked by the area display panel 1.

  In the area display panel 1, display can be performed with different gradation values between the pixel electrodes 11a to 11f by changing the voltage applied from the driving driver connected to each pixel electrode.

  Next, an operation for displaying an image in the liquid crystal display device having the above configuration will be described below with reference to a block diagram shown in FIG.

  FIG. 7 is a schematic block diagram of a video signal supply circuit for supplying video signals to the area display panel 1 and the image display panel 2 constituting the liquid crystal display device according to the present embodiment. This video signal supply circuit is provided in a liquid crystal controller or the like.

  As shown in FIG. 7, the video signal supply circuit includes a frame memory 301 that temporarily stores a video signal input from the outside, and a display on the area display panel 1 from the video signal stored in the frame memory 301. An area display signal generation circuit 302 for generating a signal, and an image display signal generation circuit 303 for generating a display signal for the image display panel 2 from the video signal stored in the frame memory 301. ing.

  The area display signal generation circuit 302 extracts only the luminance signal from the video signal stored in the frame memory 301, performs area separation and gradation level measurement to determine the gradation for each area, and displays the area display floor. The tone is determined, and this area display gradation signal is output to the area display panel 1 as an area display signal.

  On the other hand, the image display signal generation circuit 303 extracts both the luminance signal and the color signal from the video signal stored in the frame memory 301, corrects the color and gradation of the pixel in the corresponding area, and corrects the corrected color. The signal and the gradation signal are output to the image display panel 2 as an image display signal.

  Specifically, in the area display signal generation circuit 302, after extracting a luminance signal from the video signal stored in the frame memory 301, a pixel is determined in order to determine a gradation for each area with respect to the luminance signal. Mapping processing for associating an area with the position is performed to measure the gradation level. Therefore, the area display signal generation circuit 302 performs area separation and gradation level measurement.

  Next, a reference gradation is determined for each area. This reference gradation means that the entire area is displayed with this gradation, and is determined from the gradation of each pixel corresponding to the area. For example, if the gradation of the pixel group of the image display panel corresponding to a certain area is high and whitish, the pixel electrode of that area on the area display panel may be displayed with the highest gradation number of the pixel group. .

  In the liquid crystal display device of this configuration, an image display panel 2 that displays an image with both luminance signals and color signals and an area display panel 1 that displays a grayscale image from a grayscale signal generated from the luminance signal are combined. Is displayed. Therefore, the luminance information is expressed through two panels. Therefore, in a panel that expresses gradation by transmitting light, such as a transmissive liquid crystal panel, the product of the gradations of both panels becomes the display gradation, so that the area display panel 1 side for a bright image. If the tone is lowered, the image becomes dark and dark.

  On the other hand, when the entire pixel group of the image display panel 2 is expressed with dark gradation, it may be the average value of the entire luminance information of the pixels corresponding to the area, or may be set darker than the average. Good. In this way, the gradation level of the pixel corresponding to the area is measured, and the reference gradation is determined according to the character. Here, a reference gradation may be determined by providing a gradation look-up table according to the character in the circuit in advance and appropriately reading out from the look-up table according to the pixel gradation level corresponding to the area.

  As described above, when the gradation of the area display panel 1 is determined, the image on the image display panel 2 needs to be corrected accordingly. This is because, as described above, light is transmitted through two panels to display an image, and color expression is shifted unless correction is also made to color information depending on the gradation of area display.

  The image (image display signal) to the image display panel 2 generated in this way and the image (area display signal) to the area display panel 1 can be displayed in synchronization with each other to display the entire image. . In addition, after determining the gradation for area display, correction may be performed in order to make the shading of each area smoother.

  As described above, in the liquid crystal display device 10 of the present embodiment, when the image display area in the image display panel 2 is switched depending on the situation and the shape of the area changes, the pixel electrode of the area display panel 1 is changed accordingly. 11 display state also changes.

  That is, even when the screen is switched and the image display area is changed, the pixel electrode of the area display panel corresponding to the image display area similarly controls the backlight by performing gradation display. Further, the pixel electrode of the area display panel corresponding to the non-display area shields the backlight by performing black display. As a result, the image display area is brightly displayed, and the non-display area is blackened, so that high contrast can be realized.

  By the way, as a conventional display device configured by superimposing two display panels, for example, Patent Document 3 (Japanese Patent Laid-Open No. 2001-296546 (published on October 26, 2001)) and Non-Patent Document 1 (Japanese Utility Model Application Laid-Open) 6-10975 (published February 10, 1994)).

  The display assembly described in Patent Document 3 has a laminated structure of segment display panels, and each display device has a function of ON-OFF display. On the other hand, as described above, the present invention has a laminated structure of an image display panel having active elements such as TFT elements and an area display panel employing a segment display system. In this respect, the present invention is different from the above-described prior art.

  The liquid crystal display device described in Non-Patent Document 1 includes a segment type display panel (segment display panel) on the front side and a display panel (TFT display panel) having a TFT element on the back side. The TFT display panel is cut off by the black mask formed in the segment display panel. On the other hand, in the present invention, as described above, the image display panel is provided on the front side and the area display panel is provided on the back side, and the area display panel is driven to display black. It plays the role of a black mask that blocks the backlight. In this respect, it is different from the above-described prior art.

  According to the present invention, since the area display panel plays the role of light control, it is possible to increase the display contrast for each image display area and improve the display quality.

  The liquid crystal display device of the present invention can be suitably used for a display device that performs image display in which a display area and a non-display area are clearly divided into relatively large sections within a panel. Examples of such a liquid crystal display device include an in-vehicle liquid crystal display panel equipped with a car navigation system, an information display, and the like.

  According to the present invention, it is possible to realize display with high contrast without performing complicated control such as dimming the backlight in accordance with an image displayed using the backlight control circuit.

  FIG. 8 and FIG. 9 show diagrams when the liquid crystal display device of the present invention is applied to an electronic shelf label which is an example of an information display.

  The liquid crystal display panel of the liquid crystal display device 400 used as an electronic shelf label is formed by superimposing an image display panel 402 and an area display panel 401.

  Here, for example, a state (first display state) in which the image display panel 402 displays, for example, a product name and various information on the product as shown in FIG. 8A, and FIG. 9A. Display on the area display panel 401 when switching between a plurality of display states having different shapes of the image display area, such as a state of displaying the price of the product as shown (second display state) The state will be described.

  FIG. 8 is a diagram when the liquid crystal display device 400 is in the first display state. FIG. 8A is a diagram showing a display state of the image display panel 402, and FIG. 8B is a diagram showing a display state of the area display panel 401. As shown in FIG.

  FIG. 9 is a diagram when the liquid crystal display device 400 is in the second display state. FIG. 9A is a diagram illustrating a display state of the image display panel 402, and FIG. 9B is a diagram illustrating a display state of the area display panel 401.

  Next, a television receiver including the liquid crystal display device of the present invention will be described below with reference to FIGS.

  FIG. 10 shows a circuit block when the above-described liquid crystal display device 10 is used as a display device for a television receiver.

  As shown in FIG. 10, the liquid crystal display device 10 includes a Y / C separation circuit 500, a video chroma circuit 501, an A / D converter 502, a liquid crystal controller 503, a first liquid crystal panel (image display panel) 2, a second Liquid crystal panel (light control panel) 1, backlight drive circuit 505, backlight unit 3, microcomputer 507, and gradation circuit 508.

  In the liquid crystal display device 10 having the above configuration, first, an input video signal of a television signal is input to a Y / C separation circuit 500 and separated into a luminance signal and a color signal. The luminance signal and the color signal are converted into R, G, and B which are the three primary colors of light by the video chroma circuit 501, and the analog RGB signal is converted into a digital RGB signal by the A / D converter 502, and the liquid crystal Input to the controller 503.

  In the first liquid crystal panel 2, RGB signals from the liquid crystal controller 503 are input at a predetermined timing, and the respective RGB gradation voltages from the gradation circuit 508 are supplied to display an image. In addition, the second liquid crystal panel 1 also receives a signal for performing gradation display at a predetermined timing to each pixel electrode. The microcomputer 507 controls the entire system including these processes.

  Video signals are displayed based on various video signals such as video signals based on television broadcasts, video signals captured by cameras, video signals supplied via the Internet, video signals recorded on DVDs, etc. Is possible.

  Further, the tuner unit 600 shown in FIG. 11 receives a television broadcast and outputs a video signal, and the liquid crystal display device 10 displays an image (video) based on the video signal output from the tuner unit 600.

  Since the television receiver includes the liquid crystal display device 10, it is possible to realize image display with high contrast and improved display quality.

  By using the liquid crystal display device of the present invention, high contrast display can be performed. The liquid crystal display device of the present invention has a relatively large division between an image display area and a non-display area in the panel, such as an in-vehicle liquid crystal display panel equipped with a car navigation system and an information liquid crystal display panel. And can be suitably used for liquid crystal display panels that are clearly separated.

It is a perspective view which shows the structure of the liquid crystal display device concerning one embodiment of this invention. It is sectional drawing which shows the more detailed structure of the liquid crystal display device shown in FIG. FIG. 2 is a plan view showing a pixel electrode arrangement of an area display panel provided in the liquid crystal display device shown in FIG. 1. It is a figure which shows the X-X 'line cross section of the area display panel shown in FIG. It is a top view which shows the 1st display state of the liquid crystal display device shown in FIG. (A) is a figure which shows the display state of the image display panel, (b) is a figure which shows the display state of the area display panel. FIG. 6 is a plan view showing a second display state of the liquid crystal display device shown in FIG. 1. (A) is a figure which shows the display state of the image display panel, (b) is a figure which shows the display state of the area display panel. It is a block diagram which shows the drive circuit for driving the liquid crystal display device of this invention. It is a top view which shows the 1st display state in the other liquid crystal display device of this invention. (A) is a figure which shows the display state of the image display panel, (b) is a figure which shows the display state of the area display panel. It is a top view which shows the 2nd display state of the liquid crystal display device shown in FIG. (A) is a figure which shows the display state of the image display panel, (b) is a figure which shows the display state of the area display panel. It is a schematic block diagram of the television receiver provided with the liquid crystal display device of this invention. It is a block diagram which shows the relationship between the tuner part and liquid crystal display device in the television receiver shown in FIG.

Explanation of symbols

1 Area display panel (light control panel)
2 Image display panel 3 Backlight unit (light source)
DESCRIPTION OF SYMBOLS 10 Liquid crystal display device 11 (11a-11f) Pixel electrode 13 Driver for drive (drive part)
16 Signal wiring 21 (21a, 21b) Image display area 22 Non-display area

Claims (4)

An image display panel having a liquid crystal display panel, divided into an image display area and a non-display area in the liquid crystal display panel, and irradiating the image display panel with light In a liquid crystal display device comprising a light source,
A liquid crystal display panel is provided between the image display panel and the light source, and a light control panel is provided that changes the transmittance of light from the light source in accordance with an image displayed on the image display panel. And
The dimming panel has a plurality of pixel electrodes having a shape that matches the shape of the image display area in the image display panel.
A liquid crystal display device, wherein a pixel electrode that transmits light from the light source and a pixel electrode that does not transmit light from the light source are determined in accordance with the shape of the image display area. The image display panel has a plurality of display states in which the shape of the image display area is different from each other,
A pixel electrode that transmits light from the light source among the pixel electrodes provided in the light control panel is determined so as to match the shape of the image display area in each of the plurality of display states. The liquid crystal display device according to claim 1.   The liquid crystal display device according to claim 1, wherein the light control panel is provided with a drive unit that changes a gradation value of an image displayed on each of the pixel electrodes. A tuner unit that receives the television broadcast, and a liquid crystal display device that displays the television broadcast received by the tuner unit,
The said liquid crystal display device is a liquid crystal display device of any one of Claims 1-3, The television receiver characterized by the above-mentioned.

Images