JP2009093000A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve a luminance and a lifetime of a liquid crystal display device including a cylindrical screen having curvature in a horizontal direction. <P>SOLUTION: A fluorescent tube 30 curved in the same direction as that of a liquid crystal display panel 10 is installed in a horizontal direction in a light source of a back light of the liquid crystal display panel 10 having the curvature in the horizontal direction. Accordingly, the phenomenon of the vapor of the mercury in the fluorescent tube 30 gathering downward in the fluorescent tube 30 to shorten the lifetime of fluorescent tube, which causes a problem when the fluorescent tube 30 is erected for use, can be avoided. Also, the screen luminance can be made uniform by curving the fluorescent tube 30 in the same direction as that of the liquid crystal display panel 10. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device having a curved display screen.

  The demand for liquid crystal display devices is expanding from computer displays, mobile phone terminals, etc. to TVs and the like because the display device can be made thin and the weight does not increase. The liquid crystal display device is also characterized by a flat screen.

  On the other hand, since the liquid crystal display device can be made thin, development for making the liquid crystal display device a flexible display is also underway. An example of such development is “Non-Patent Document 1”. “Non-Patent Document 1” has the following description. A liquid crystal display panel is formed by sandwiching a polymer dispersed ferroelectric liquid crystal between two plastic substrates and maintaining a gap between the substrates by polymer columns. In this case, the backlight needs to be formed flexibly. In “Non-patent Document 1”, this is achieved by installing an LED on the side of a flexible light guide plate.

H.SATO et. Al. “A4-Sized LCDs with Flexible Light Guide Plate” International Display Workshop (IDW) 06

  The purpose of the development of a conventional flexible liquid crystal display is to make the display itself flexible. In other words, studies have been made on the assumption that the backlight is also flexible. Therefore, how to make the entire display device thin, how to make the backlight flexible, etc. has not yet been prospected for practical use. In order to make the backlight flexible, development of a light guide plate material for making the light guide plate flexible is also an important issue.

  In order to make the light guide plate flexible, it is necessary to make the light source flexible. In this case, it is necessary to install an LED on the side of the flexible light guide plate and direct the light from the LED to the liquid crystal display panel side. is there. In order to efficiently direct light from the light source to the liquid crystal display panel, an optical pattern is formed on the surface (one side or both sides) of the light guide plate. Furthermore, since the light guide plate itself is also curved, the design of the optical pattern becomes very complicated.

  As described above, the conventional flexible display has a particularly complicated backlight configuration, and there are many problems to be overcome in terms of material development, cost, reliability, and the like until realization. On the other hand, a place where a thin display having a curved display surface is installed, for example, a side surface of a column such as a station, or a side surface of a train, a bus, or the like. In addition, examples of applications where the display itself is a curved surface include slot machine gaming machines and various gaming machines existing in game centers.

  In the display for such use, a display having a curved display screen is required, but the display device itself does not need to be flexible. In such applications, the display screen does not need to be spherical, and a cylindrical curved surface is often sufficient. In such applications, a bright screen is required. For this purpose, the backlight needs to have high luminance, and a fluorescent light tube is most advantageous as a light source that enables this. The fluorescent tube includes a cold cathode fluorescent tube and a hot cathode fluorescent tube. Since the cold cathode fluorescent tube can be made thin, it is suitable for a thin backlight. On the other hand, the hot cathode fluorescent tube has excellent luminance. Therefore, it may be selected depending on the use of the display, that is, taking into consideration the thickness of the entire display device and the required luminance.

  FIG. 14 shows an example of a backlight 20 used for a cylindrical screen having a curvature in the horizontal direction. In this example, a linear fluorescent tube 30 is used, and the arrangement of the fluorescent tube 30 is curved in accordance with the curved surface of the screen. The fluorescent tube 30 is installed in the vertical direction. By the way, the inside of the fluorescent tube 30 is filled with mercury vapor. Since mercury molecules are heavy, when the fluorescent tube 30 is used in an upright position, mercury vapor collects in the lower portion of the fluorescent tube 30 due to gravity, resulting in non-uniform mercury vapor density.

  Thus, when the density of the mercury vapor becomes non-uniform, the life of the fluorescent tube 30 is deteriorated. According to experiments, when the fluorescent tube 30 is used in an upright position, the life of the fluorescent tube 30 is about 70% as compared with the case where the fluorescent tube 30 is used sideways and the density of mercury vapor is not particularly problematic. Become. The life of the entire display is often determined by the life of the light source of the backlight 20. Therefore, the deterioration of the life of the fluorescent tube 30 is extremely important for the display.

  Another problem with the arrangement of the fluorescent tube 30 as shown in FIG. 14 is as follows. That is, many displays are long in the horizontal direction and short in the vertical direction. In the arrangement as shown in FIG. 14, in order to arrange the fluorescent tubes 30 in the long axis direction of the display, it is necessary to use more fluorescent tubes 30 in order to make the pixels uniform brightness. This pushes up display manufacturing costs

  The present invention solves the above-described problems, and a fluorescent tube having a curvature in the same direction as the liquid crystal display panel is used in the horizontal direction as a light source for a backlight of a cylindrical liquid crystal display panel having a curvature in the horizontal direction. Take the configuration to install. Specific means are as follows.

  (1) A TFT substrate on which a pixel electrode and a TFT are formed, a color filter substrate on which a color filter is formed, and a liquid crystal is sandwiched between the color filter substrate and the TFT substrate, on the color filter substrate Is a liquid crystal display panel in which an upper polarizing plate is attached and a lower polarizing plate is attached under the TFT substrate, and a liquid crystal display device having a backlight, wherein the liquid crystal display panel is in a horizontal direction. A liquid crystal display device characterized in that a cylindrical curved surface having a curved surface and a fluorescent tube curved in the same direction as the liquid crystal display panel is installed in the backlight in the lateral direction.

  (2) The fluorescent tube has a certain radius of curvature, and the distance between the fluorescent tube and the liquid crystal display panel is, when the average of the distance between the fluorescent tube and the liquid crystal display panel is m, The liquid crystal display device according to (1), which is within m ± 10%.

  (3) The backlight is provided with a plurality of fluorescent tubes, the plurality of fluorescent tubes have a constant radius of curvature, and the distance between the fluorescent tube and the liquid crystal display panel is the plurality of fluorescent tubes. The liquid crystal display device according to (1), wherein the average distance between each fluorescent tube and the liquid crystal display panel is m ± 10% or less.

  (4) The liquid crystal display device according to (1), wherein the TFT substrate and the color filter substrate are made of glass.

  (5) A TFT substrate on which a pixel electrode and a TFT are formed, a color filter substrate on which a color filter is formed, and a liquid crystal is sandwiched between the color filter substrate and the TFT substrate. Has an upper polarizing plate, a liquid crystal display panel having a lower polarizing plate attached to the lower side of the TFT substrate, a frame and a backlight for covering and surrounding the periphery of the liquid crystal display panel In the liquid crystal display device, the liquid crystal display panel has a cylindrical curved surface having a curvature in a horizontal direction, the backlight has a diffusion plate curved in the same direction as the liquid crystal display panel, and the same direction as the display area A fluorescent tube curved in a horizontal direction is installed in the horizontal direction, and the liquid crystal display panel is held in the horizontal direction by being sandwiched between the frame and the diffusion plate. The liquid crystal display device characterized by having a surface.

  (6) The liquid crystal display device according to (5), wherein a front plate having a curved surface having a lateral curvature is provided between the frame and the liquid crystal display panel.

  (7) A TFT substrate on which pixel electrodes and TFTs are formed, a color filter substrate on which color filters are formed, and a liquid crystal is sandwiched between the color filter substrate and the TFT substrate, on the color filter substrate Is a liquid crystal display panel in which an upper polarizing plate is attached and a lower polarizing plate is attached under the TFT substrate, and a liquid crystal display device having a backlight, wherein the liquid crystal display panel is in a horizontal direction. The backlight is provided with a fluorescent tube having a bent portion in the lateral direction, and the distance between the fluorescent tube and the liquid crystal display panel is the same as that of the fluorescent tube and the liquid crystal display panel. A liquid crystal display device, wherein an average distance from the liquid crystal display panel is m, and is within m ± 10%.

  (8) The liquid crystal display device according to (7), wherein the bent portion of the fluorescent tube is parallel to the bent portion.

  (9) A TFT substrate on which pixel electrodes and TFTs are formed, a color filter substrate on which color filters are formed, and a liquid crystal is sandwiched between the color filter substrate and the TFT substrate, on the color filter substrate Is a liquid crystal display panel in which an upper polarizing plate is attached and a lower polarizing plate is attached under the TFT substrate, and a liquid crystal display device having a backlight, wherein the liquid crystal display panel is in a horizontal direction. The backlight is provided with a fluorescent tube having a portion with a large radius of curvature and a portion with a small radius of curvature in the lateral direction, and the fluorescent tube and the liquid crystal display panel. The distance between the fluorescent tube and the liquid crystal display panel is m ± 10% or less, where m is the average distance between the fluorescent tube and the liquid crystal display panel.

  According to the present invention, in a liquid crystal display device having a cylindrical screen having a curvature in the horizontal direction, a fluorescent tube that is curved in the same direction as the screen is installed in the horizontal direction as a backlight light source. This prevents mercury vapor from collecting at one end of the fluorescent tube. Therefore, the life of the fluorescent tube can be improved, and consequently the life of the liquid crystal display device can be improved.

  Further, according to the present invention, a fluorescent tube curved in the same direction as the screen is used as a light source for a backlight of a liquid crystal display panel having a cylindrical screen having a curvature in the horizontal direction and a long screen in the horizontal direction. Since it is installed in the direction, the number of fluorescent tubes can be reduced, and the cost of the liquid crystal display device can be reduced.

  The detailed contents of the present invention will be disclosed according to the embodiments.

  FIG. 1 is an external view of a display device according to the first embodiment. FIG. 1 shows a display whose screen is convex outward. Such a display device is used for amusement applications such as slot machine gaming machines. In FIG. 1, the liquid crystal display panel 10 is curved outward. The liquid crystal display panel 10 curved outward can be formed by using plastic as a substrate as described in, for example, “Non-Patent Document 1”. On the other hand, the liquid crystal display panel 10 having a curved screen can be formed by forming the substrate from glass and thinning the glass substrate.

  In FIG. 1, a liquid crystal display panel 10 is covered with a curved front frame 11 leaving a display portion. A backlight 20 is installed on the back surface of the liquid crystal display panel 10. FIG. 4 is an exploded cross-sectional view of the AA cross-sectional view of FIG. 1. The liquid crystal display panel 10 includes a TFT substrate 101 on which thin film transistors (TFTs) and pixel electrodes are formed, and a color filter substrate 102 on which color filters and the like are formed. A polarizing plate is attached above and below the liquid crystal cell with the liquid crystal sandwiched between them. Moreover, the backlight 20 is comprised from various optical components and a light source so that it may demonstrate later. In this embodiment, a fluorescent tube 30 is used as the light source. The fluorescent tube 30 is driven by an inverter, but is omitted in FIG.

  FIG. 2 is a schematic diagram showing only the backlight 20 portion of FIG. The backlight 20 includes not only the fluorescent tube 30 that is a light source but also many optical components. However, in the backlight 20 of FIG. 2, components other than the fluorescent tube 30 are omitted for the sake of clarity. The fluorescent tube 30 used in FIG. 2 is curved with a curvature R2. The fluorescent tubes 30 are installed in the horizontal direction and arranged in the vertical direction. The thickness of the fluorescent tube is, for example, about φ3 mm to φ4 mm for a liquid crystal display device for TV and about φ2.4 mm to φ2.6 mm for a liquid crystal display device for a monitor of 10 inches to 15 inches.

  As shown in FIG. 2, since the fluorescent tube 30 is installed in the horizontal direction, the problem that mercury vapor in the tube of the fluorescent tube 30 collects at one end of the fluorescent tube 30 does not occur. Therefore, according to the present embodiment, it is possible to prevent life deterioration of the fluorescent tube 30 due to non-uniform mercury vapor pressure. The fluorescent tube 30 is curved toward the liquid crystal display panel 10 with a radius of curvature R2. This is because the distance between the liquid crystal display panel 10 and the fluorescent tube 30 is kept constant because the liquid crystal display panel 10 is curved outward. Thus, in this embodiment, since the fluorescent tube 30 is curved and the distance from the liquid crystal display panel 10 is made constant, the screen brightness of the liquid crystal display panel 10 can be made uniform.

  In FIG. 2, the upper surface of the backlight 20 is actually a diffusion sheet described later, but this radius of curvature is R1. Since this diffusion sheet comes into contact with the liquid crystal display panel 10, it becomes equal to the radius of curvature R 1 inside the liquid crystal display panel 10. In FIG. 2, since the difference between the radius of curvature R2 of the fluorescent tube 30 and the radius of curvature inside the liquid crystal display panel 10 is slight, there is no problem even if they are the same.

  3 is a cross-sectional view taken along the line AA in FIG. In FIG. 3, the liquid crystal display panel 10 is curved outward. Although details will be described later, the originally flat liquid crystal display panel 10 is curved by the curved front frame 11. A backlight 20 is installed on the back surface of the liquid crystal display panel 10, but in FIG. 3, only the fluorescent tube 30 is shown in the backlight 20 part, and other optical components are omitted. The backlight 20 is accommodated in the back frame 12.

  In FIG. 3, the fluorescent tube 30 is curved with a radius of curvature R2, and the liquid crystal display panel 10 is curved with a radius of curvature R1. The distance between the front surface of the fluorescent tube 30 and the rear surface of the liquid crystal display panel 10 can be made uniform by making d constant over the entire surface of the liquid crystal display device, and the optical design can be facilitated. The distance d between the front surface of the fluorescent tube 30 and the back surface of the liquid crystal display panel 10 varies depending on component variations, assembly accuracy, and the like. However, by setting the value of d within 10% over the entire display device, the brightness of the screen is constant. I can keep it.

  FIG. 4 is a detailed cross-sectional view in a state in which the parts in the AA cross section of FIG. 1 are separated. In FIG. 4, a front plate 13 is installed inside a front frame 11 made of metal. The front plate 13 is made of a transparent resin such as acrylic and has a thickness of about 0.5 mm. The front plate 13 is formed by a press so as to be a cylindrical surface having a predetermined curvature. Since the front plate 13 also has a role of mechanically protecting the liquid crystal display panel 10, it is relatively thick and has a thickness of about 0.5 mm.

  A liquid crystal display panel 10 is installed under the front plate 13. The liquid crystal display panel 10 is obtained by bonding an upper polarizing plate 103 and a lower polarizing plate 104 to a liquid crystal cell. The liquid crystal cell includes a TFT substrate 101 on which a thin film transistor (TFT) and pixel electrodes are formed, a color filter substrate 102 on which a color filter and the like are formed, and a liquid crystal sandwiched between the TFT substrate 101 and the color filter substrate 102. Has been. An image is formed by controlling the light from the backlight 20 by controlling the voltage applied to the liquid crystal molecules for each pixel by the video signal.

  Since the light needs to be polarized in order to control the light with the liquid crystal, the light from the backlight 20 is polarized by the lower polarizing plate 104. This polarized light is controlled by the liquid crystal, and the light transmitted through the liquid crystal cell is again polarized (analyzed) by the upper polarizing plate 103, so that a human can recognize the image.

  FIG. 5 is an exploded perspective view of the portion of the liquid crystal display panel 10 above the backlight 20 in FIG. Details of the backlight 20 in FIG. 5 are omitted. In FIG. 5, as described above, the front frame 11 and the front plate 13 have predetermined curvatures formed in advance by pressing. In FIG. 5, the liquid crystal cell, the upper polarizing plate 103, and the lower polarizing plate 104 are originally flat plates, but have a curvature by being along the front plate 13 or the front frame 11 having a curvature. Here, although the liquid crystal cell is made of glass, after the liquid crystal cell is manufactured, the TFT substrate 101 and the color filter substrate 102 are polished to be thinned so as to have a curved surface easily.

  The degree to which the glass can be curved is determined by the balance with the thickness of the glass. FIG. 6A is a diagram showing the thickness of the liquid crystal display panel 10 and the range in which the liquid crystal display panel 10 can be bent without breaking the glass. FIG. 6B is a diagram showing the parameters of FIG. As shown in FIG. 6B, the liquid crystal display panel 10 includes a TFT substrate 101 on which TFTs and pixel electrodes are formed, and a color filter substrate 102 on which color filters and the like are formed. The TFT substrate 101 and the color filter substrate. Liquid crystal is sandwiched between 102. The liquid crystal is sealed with a sealing material 113.

  The glass substrate which comprises the liquid crystal display panel 10 is standardized as 0.7 mm or 0.5 mm, for example. Therefore, when the glass substrate is thinned in order to provide more curvature, after the liquid crystal display panel 10 is formed, the outside of the glass substrate is polished and thinned. For polishing, mechanical polishing and chemical polishing are used in combination. In this case, both the TFT substrate 101 and the color filter substrate 102 are polished. The liquid crystal layer 114 is several μm, and can be ignored in consideration of the thickness t of the entire liquid crystal display panel 10.

  In FIG. 6, the vertical axis represents the radius of curvature of the liquid crystal display panel 10. The definition of the curvature radius is a curvature radius inside the liquid crystal display panel 10 as shown in FIG. The glass thickness on the horizontal axis in FIG. 6A represents the thickness t of the entire liquid crystal display panel 10. That is, in FIG. 6A, when the horizontal axis is 0.2 mm, the thickness of the TFT substrate 101 or the color filter substrate 102 is 0.1 mm.

  A straight line G in FIG. 6 (a) indicates a glass breaking limit line. That is, if it is below the straight line G, the glass substrate is broken, and if it is above this straight line, the glass substrate is not broken. When the radius of curvature is R and the thickness of the liquid crystal display panel 10 is t, the straight line G has a relationship of R = 400 t. That is, when the radius of curvature R is 400 times or less of the thickness, the glass substrate is broken. However, if scratches or the like are present in the glass, the glass is broken even slightly above the straight line G. Therefore, in an actual product, it is desirable to have a margin twice as large as the straight line G and use a region on or above the straight line of R = 800t. In the product, the relationship between the glass substrate and the curvature is set with a margin above the straight line G as shown in FIG.

  Returning to FIG. 4, a backlight 20 including optical components is installed under the lower polarizing plate 104. The backlight 20 includes a back frame 12, a light source, a diffusion plate 205, and various optical sheets. In FIG. 4, the inner side of the back frame 12 is a reflecting surface, and the light from the fluorescent tube 30 is increased by reflecting the light from the fluorescent tube 30 toward the liquid crystal display panel 10. The fluorescent tube 30 is installed on the back frame 12 via a socket 31. The fluorescent tube 30 is curved toward the liquid crystal display panel 10 with a radius of curvature R2. This is to keep the distance between the liquid crystal display panel 10 and the fluorescent tube 30 within a certain value.

  The light exiting the fluorescent tube 30 or the light reflected by the back frame 12 first enters the diffusion plate 205. The diffusion plate 205 is made of polycarbonate having a thickness of about 2 mm and has a certain degree of rigidity. The diffusion plate 205 is formed so as to have the same curvature as the curved surface of the screen of the liquid crystal display panel 10 at the time of molding. Each optical sheet is curved along the diffusion plate 205.

  The diffuser plate 205 has a role of making light from the light source uniform. That is, the diffusion plate 205 prevents only the fluorescent tube 30 from being brightened and prevents the screen luminance from becoming uneven. Since the diffusion plate 205 diffuses light, the light transmittance is sacrificed to some extent. Light exiting the diffusion plate 205 passes through the lower diffusion sheet 204. The lower diffusion sheet 204 has a role of making the light emitted from the diffusion plate 205 more uniform.

  A lower prism sheet 203 is installed on the lower diffusion sheet 204. The lower prism sheet 203 is formed with a large number of prisms extending in the horizontal direction of the screen, for example, at a constant pitch, and light that attempts to spread in the vertical direction of the screen from the backlight 20 in the vertical direction of the screen of the liquid crystal display panel 10. Focus. That is, the front luminance can be increased by using a prism sheet. An upper prism sheet 202 is installed on the lower prism sheet 203. The upper prism sheet 202 is formed with a large number of prisms extending at a constant pitch in a direction perpendicular to the lower prism sheet 203, for example, in the vertical direction of the screen. Thereby, the light that spreads in the horizontal direction of the screen from the backlight 20 is focused in the vertical direction with the surface of the liquid crystal display panel 10. In this way, by using the lower prism sheet 203 and the upper prism sheet 202, it is possible to focus light that is going to spread in the vertical and horizontal directions of the screen in the vertical direction of the screen.

  An upper diffusion sheet 201 is installed on the upper prism sheet 202. In the prism sheet, prisms extending in a certain direction are formed at a pitch of 50 μm, for example. That is, bright and dark stripes are formed with a pitch of 50 μm. On the other hand, the liquid crystal display panel 10 is formed with scanning lines at a constant pitch in the horizontal direction of the screen or data signal lines in the vertical direction of the screen. Therefore, bright and dark stripes are formed by the scanning line pitch or the data signal line pitch. Then, the bright and dark stripes of the prism and the bright and dark stripes of the liquid crystal display panel 10 cause interference to generate moiré. The upper diffusion sheet 201 has a role of reducing this moire by a diffusion action.

  The optical sheet described above is placed on the diffusion plate 205. Since each optical sheet is as thin as about 50 μm to 150 μm, the same curvature as that of the diffusion plate 205 can be obtained simply by placing it on the diffusion plate 205. On the other hand, the liquid crystal display device has the same curvature as the curved surface previously formed in the frame by being accommodated in the frame. Therefore, the distance between the fluorescent tube 30 as the light source and the liquid crystal display panel 10 can be set to be constant, and the brightness of the screen can be made constant.

  As shown in FIG. 2, in this embodiment, long fluorescent tubes 30 are installed along the long side in the horizontal direction (horizontal direction) and arranged in the short side direction (vertical direction). Therefore, the brightness of the screen can be made uniform with fewer fluorescent tubes 30 than when the fluorescent tubes 30 are erected and arranged in the horizontal direction.

  As described above, according to this embodiment, since the fluorescent tube 30 is installed in the horizontal direction using the fluorescent tube 30 curved with respect to the cylindrical screen curved in the horizontal direction, mercury vapor is caused to flow by the gravity. The problem of gathering at one end of 30 can be avoided. Thereby, the life of the fluorescent tube 30 can be improved, and therefore the life of the display device can be improved. Furthermore, the number of fluorescent tubes 30 can be reduced on a screen that is longer in the horizontal direction than in the vertical direction.

  Example 1 is a case where the screen of the liquid crystal display device is convex outward. An advantage of the present invention using a liquid crystal display device is that it can be formed even when the screen is concave. When the screen is concave, the characteristics of the liquid crystal display device can be further utilized.

  FIG. 7 shows viewing angle characteristics of the liquid crystal display panel 10. One problem with the image quality of the liquid crystal display panel 10 is that brightness, chromaticity, and the like change depending on the angle at which the screen is viewed. FIG. 7 shows viewing angle characteristics in a normal TN liquid crystal display device. In FIG. 7, the vertical axis represents luminance. The brightness when viewed from the vertical direction of the screen is 100%. The horizontal axis in FIG. 7 is the angle at which the screen is viewed. That is, the angle when the screen is viewed from the vertical direction is set to 0 degree, and the angle deviated from the vertical direction is taken on the horizontal axis. As shown in FIG. 7, when the liquid crystal screen is shifted 30 degrees from the vertical direction, the luminance is reduced to nearly 40%. In addition, since the decrease in luminance is different for each color, there also arises a problem that the color changes depending on the viewing angle.

  This viewing angle characteristic varies depending on the method of the liquid crystal display device. For example, an IPS (In Plane Switching) type liquid crystal that controls light transmission by rotating liquid crystal molecules in a direction parallel to the TFT substrate 101 exhibits a viewing angle characteristic superior to that of a normal TN type liquid crystal. . In any case, when the screen is flat or the screen is convex outward, it is necessary to deal with it by improving the viewing angle characteristics of the liquid crystal display panel 10.

  FIG. 8 is an external view of the liquid crystal display device according to this embodiment. 8 differs from FIG. 1 in that the screen has a concave curved surface on the outside. 1 except that the screen is concave outward. That is, by installing the liquid crystal display panel 10 in a frame that is concave outward, the liquid crystal display panel 10 is curved to form a screen with a curved surface. When the liquid crystal display panel 10 is made of glass, the relationship between the radius of curvature of the liquid crystal display panel 10 and the thickness of the liquid crystal display panel 10 is the same as in FIG. A backlight 20 is installed on the back surface of the liquid crystal display panel 10.

  FIG. 9 is a schematic view of the backlight 20 of FIG. In FIG. 9, optical components other than the fluorescent tube 30 are omitted. The fluorescent tube 30 of FIG. 9 is curved with a radius of curvature R2, and the upper surface of the backlight 20 in FIG. 9 is a diffusion sheet. This diffusion sheet is curved with a radius of curvature R1 similar to that of the liquid crystal display panel 10. ing. R1 and R2 are a slight difference. Therefore, even if R1 and R2 are the same, the distance between the fluorescent tube 30 and the liquid crystal display panel 10 can be kept substantially constant. By arranging the fluorescent tubes 30 in this way, the life of the fluorescent tubes 30 can be improved, and the number of fluorescent tubes 30 in the display device can be reduced as in the first embodiment.

  If the screen is concave outward as in this embodiment, it is very effective in improving the viewing angle characteristics of the liquid crystal display. FIG. 10 shows this state. When viewing the liquid crystal screen from the front, the viewing angle becomes a problem at the periphery of the screen. Therefore, as shown in FIG. 10, when the periphery of the screen is concave outward, the angle at which the liquid crystal screen is viewed is closer to a right angle than when the screen is flat. That is, it is close when viewing the front of the screen.

  As shown in FIG. 7, the luminance characteristics are greatly improved only by improving the viewing angle by about 20 degrees. The same applies to the color difference. Such an effect is particularly effective when the position where the display is viewed is fixed, such as an automobile display. As shown in FIG. 10, if the position where the display is viewed matches the radius of curvature of the display, any position on the display screen can be viewed as clearly as when viewed from the front. For example, in the case of an automobile display, if the distance between the display and a person is 50 cm, the curvature radius of the display is set to 50 cm, so that an image similar to that seen from the front can be obtained over the entire screen of the display. Even if the curvature of the display is not sufficient, a great effect can be obtained by providing a slight curvature.

  FIG. 11 is an explanatory diagram when the display is a TV. In FIG. 11, the liquid crystal display panel 10 constituting the display has a concave curved surface on the outside. In the case of TV, the optimal position for watching TV is said to be a position that is twice to four times the vertical diameter H of the screen. FIG. 11 shows an example in which a human is watching TV at a position 3H from the screen.

  When watching TV at this position, if the radius of curvature of the screen is 3H, a clear image similar to that seen at the center of the screen can be seen at any position on the screen. In the case of the liquid crystal display panel 10, the viewing angle characteristics do not change significantly in the vertical direction of the screen compared to the horizontal direction. Therefore, the curvature may be set in the horizontal direction of the screen.

  For example, when viewing a 37-inch TV with an aspect ratio of 16: 9, the vertical length of the screen is 46 cm. Then, the position of 3H is about 1.4 m. Therefore, if a curvature radius of 1400 mm is provided on the screen, a good image can be obtained over the entire screen. On the other hand, if the optimal position for watching TV is four times the screen vertical diameter H, that is, the position of 4H is good, the curvature radius in the horizontal direction of the screen may be set to 4H. Incidentally, in this case, if it is a 37-inch TV, a radius of curvature of about 1870 mm may be provided.

  In a TV or the like, the optical sheet used for the backlight 20 of the liquid crystal display device is not necessarily configured as shown in FIG. In the case of a TV or the like, since the commercial power can be used instead of the battery, the power consumption of the backlight 20 is not so much a problem as compared with the case of a notebook personal computer or a mobile phone. On the other hand, focusing of the light from the backlight 20 is not so required. Therefore, the lower prism sheet 203 and the upper prism sheet 202 shown in FIG. 4 can be omitted. On the other hand, depending on the case, a plurality of diffusion sheets may be used.

  As described above, in this embodiment, by using the curved fluorescent tube 30 of the backlight 20, the lifetime of the fluorescent tube 30 can be improved and the number of the fluorescent tubes 30 can be reduced, and the viewing angle characteristics can be improved. Since it can be improved, it is very suitable for a liquid crystal TV. Further, this embodiment is very suitable for a system in which the viewing position is always fixed, such as a display for an automobile.

  In Example 1 and Example 2, the fluorescent tube 30 is curved with a specific curvature. After the fluorescent tube 30 is formed into a straight rod-like fluorescent tube 30, it is bent so as to have a predetermined curvature. It may be difficult to curve the straight rod-shaped fluorescent tube 30 with a certain radius of curvature. If the fluorescent tube 30 having the shape as shown in FIG. 12 is used, it is not always necessary to curve the fluorescent tube 30 with a certain radius of curvature.

  In FIG. 12, the two portions of the fluorescent tube 30 are bent with a radius of curvature r1, and the other portions, s1, s2, etc. are straight lines. Also in this case, when the average distance between the liquid crystal display panel 10 and the fluorescent tube 30 between the end portions of the fluorescent tube 30 is m, the distance between the fluorescent tube 30 and the liquid crystal display panel 10 in each place. Should not be far from the value of m. For example, it is desirable that the distance d1 between the fluorescent tube 30 and the liquid crystal display panel 10 in the center of the display and the distance d2 between the fluorescent tube 30 and the liquid crystal display panel 10 in the periphery of the display are within m ± 10%.

  FIG. 13 shows a case where the liquid crystal display panel 10 has a larger screen or a case where the radius of curvature is small. In FIG. 13, the fluorescent tube 30 is bent at four places with a radius of curvature r2 or a radius of curvature r3. The other portions, s1, s2, and s3 are straight lines. Also in this case, the distances d1, d2, and d3 between the fluorescent tube 30 and the liquid crystal display panel 10 at the center, middle, and periphery of the display are such that the average distance between the liquid crystal display panel 10 and the fluorescent tube 30 is within m ± 10% of m. It is desirable to do.

  12 and 13 may be a curve having a radius of curvature larger than the radius of curvature r1, r2, r3, etc. of the bent portion instead of the straight line such as s1, s2, s3 of the fluorescent tube 30 in FIGS.

  In the above example, the liquid crystal display panel 10 is curved with a specific radius of curvature. However, depending on the application, the radius of curvature of the liquid crystal display panel 10 may have, for example, a large radius of curvature near the center and a small radius of curvature in the peripheral portion. In such a case, the use of the fluorescent tube 30 as shown in FIG. 12 or FIG. 13 makes it easy to keep the distance between the fluorescent tube 30 and the liquid crystal display panel 10 within a specific value.

1 is an overview diagram of a liquid crystal display device of Example 1. FIG. 1 is a schematic diagram of a backlight of Example 1. FIG. It is AA sectional drawing of FIG. FIG. 2 is an exploded cross-sectional view of the AA cross-sectional view of FIG. 1. It is a disassembled perspective view of the liquid crystal display panel of FIG. It is a graph which shows the relationship between the curvature of glass, and thickness. It is an example of the viewing angle characteristic of a liquid crystal display panel. 6 is an overview diagram of a liquid crystal display device of Example 2. FIG. 6 is a schematic diagram of a backlight of Example 2. FIG. It is a schematic diagram in the case of visually recognizing a concave screen. It is a schematic diagram in the case of visually recognizing a concave TV screen. This is an example using a partially bent fluorescent tube. It is another example which uses the fluorescent tube partially bent. This is an example in which a fluorescent tube is vertically installed in the backlight.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display panel, 11 ... Front frame, 12 ... Rear frame, 13 ... Front plate, 20 ... Back light, 30 ... Fluorescent tube, 31 ... Socket, 101 ... TFT substrate, 102 ... Color filter substrate, 103 ... Upper polarization Reference numeral 104: Lower polarizing plate 113: Sealing material 114: Liquid crystal layer 201: Upper diffusion sheet 202: Upper prism sheet 203: Lower prism sheet 204: Lower diffusion sheet 205: Diffusion plate

Claims (9)

A liquid crystal is sandwiched between the TFT substrate on which the pixel electrode and the TFT are formed, a color filter substrate on which the color filter is formed, and the color filter substrate and the TFT substrate. A liquid crystal display panel on which a plate is attached and a lower polarizing plate is attached under the TFT substrate; and a liquid crystal display device having a backlight,
The liquid crystal display panel has a cylindrical curved surface having a curvature in the horizontal direction, and the backlight is provided with a fluorescent tube curved in the same direction as the liquid crystal display panel in the horizontal direction. Display device.   The fluorescent tube has a certain radius of curvature, and the distance between the fluorescent tube and the liquid crystal display panel is m ± 10, where m is the average distance between the fluorescent tube and the liquid crystal display panel. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is within%.   The backlight is provided with a plurality of fluorescent tubes, the plurality of fluorescent tubes have a certain radius of curvature, and the distance between the fluorescent tube and the liquid crystal display panel is determined by the plurality of fluorescent tubes. 2. The liquid crystal display device according to claim 1, wherein m is within ± 10%, where m is the average distance between the liquid crystal display panel and the liquid crystal display panel.   The liquid crystal display device according to claim 1, wherein the TFT substrate and the color filter substrate are made of glass. A liquid crystal is sandwiched between the TFT substrate on which the pixel electrode and the TFT are formed, a color filter substrate on which the color filter is formed, and the color filter substrate and the TFT substrate. A liquid crystal display panel having a plate attached and a lower polarizing plate attached to the lower side of the TFT substrate; a liquid crystal display device having a frame and a backlight that covers and surrounds the periphery of the liquid crystal display panel Because
The liquid crystal display panel has a cylindrical curved surface having a curvature in the horizontal direction, and the backlight has a diffusion plate curved in the same direction as the liquid crystal display panel and a fluorescent tube curved in the same direction as the display area. Installed in the direction,
The liquid crystal display device, wherein the liquid crystal display panel has a curved surface in a horizontal direction by being sandwiched between the frame and the diffusion plate.   6. The liquid crystal display device according to claim 5, wherein a front plate having a curved surface having a curvature in a lateral direction is installed between the frame and the liquid crystal display panel. A liquid crystal is sandwiched between the TFT substrate on which the pixel electrode and the TFT are formed, a color filter substrate on which the color filter is formed, and the color filter substrate and the TFT substrate. A liquid crystal display panel on which a plate is attached and a lower polarizing plate is attached under the TFT substrate; and a liquid crystal display device having a backlight,
The liquid crystal display panel has a cylindrical curved surface having a curvature in the horizontal direction, and a fluorescent tube having a bent portion is installed in the horizontal direction in the backlight, and the distance between the fluorescent tube and the liquid crystal display panel Is a liquid crystal display device that is within m ± 10%, where m is the average distance between the fluorescent tube and the liquid crystal display panel.   The liquid crystal display device according to claim 7, wherein the bent portion of the fluorescent tube is parallel to the bent portion. A liquid crystal is sandwiched between the TFT substrate on which the pixel electrode and the TFT are formed, a color filter substrate on which the color filter is formed, and the color filter substrate and the TFT substrate. A liquid crystal display panel on which a plate is attached and a lower polarizing plate is attached under the TFT substrate; and a liquid crystal display device having a backlight,
The liquid crystal display panel has a cylindrical curved surface having a curvature in the horizontal direction, and the backlight is provided with a fluorescent tube having a large curvature radius part and a small curvature radius part in the lateral direction, The distance between the fluorescent tube and the liquid crystal display panel is m ± 10% or less, where m is the average distance between the fluorescent tube and the liquid crystal display panel.

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