JP2006162647A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device displaying an image under high contrast and widening its visual field angle. <P>SOLUTION: In the liquid crystal display device wherein a liquid crystal is interposed between upper and lower substrates having transparent electrodes on respective inner surfaces thereof, the transparent electrode 73 of the upper substrate and the transparent electrode 63 of the lower substrate are opposed to each other to form a display pixel region A. A plurality of aperture parts 73a to be small holes are provided on at least one transparent electrode of the transparent electrodes 73 and 63. The aperture part 73a has 4 to 30 μm size and the ratio of the sum total area of the plurality of aperture parts to the area of the display pixel region A is 10 to 70%. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, and more particularly to a display with a wide viewing angle.

  In general, TN (twisted nematic) liquid crystal, STN (super twisted nematic) liquid crystal, and the like are widely used as liquid crystal display devices. These liquid crystal display devices are often used with a backlight on the back side of the liquid crystal display device in order to brighten the display.

  FIG. 11 shows a cross-sectional view of a main part of a liquid crystal display device having an extremely simple configuration. Here, the liquid crystal display device 20 has a configuration in which the lower substrate 1 and the upper substrate 11 are arranged to face each other with a certain gap therebetween, and the liquid crystal 17 is sealed through a sealing material 19. And the upper polarizing plate 15 is stuck on the outer side of the upper substrate 11, and the lower polarizing plate 5 is stuck on the outer side of the lower substrate 1 to complete the liquid crystal display device 20. Here, the lower substrate 1 includes a lower transparent substrate 2 made of transparent glass, a transparent ITO film provided on the upper surface thereof, a lower transparent electrode 3 also called a common electrode, and the lower transparent electrode 3 and the lower transparent substrate. 2 and a lower alignment film 4 provided on the substrate 2. On the other hand, the upper substrate 11 is made of an upper transparent substrate 12 made of transparent glass, a transparent ITO film provided on the lower surface thereof, an upper transparent electrode 13 also called a segment electrode, and the upper transparent electrode 13 and the upper transparent substrate. The upper alignment film 14 is provided on the upper alignment film 14. Although not shown, a spacer ball having a certain particle diameter is sandwiched between the upper and lower substrates 11 and 1 so as to face each other with a certain gap, and the liquid crystal 17 is sealed with a sealant 19. Take the structure.

  FIG. 11 shows a state in which a voltage is applied to the upper and lower transparent electrodes 13 and 3. The liquid crystal 17 is divided into a liquid crystal molecule 17b standing up and down and a liquid crystal molecule 17a lying on the left and right. Shown in a separate state. When a predetermined voltage is applied to the upper and lower transparent electrodes 13 and 3, the liquid crystal molecules 17 b sandwiched between the upper and lower transparent electrodes 13 and 3 stand up. A portion sandwiched between the upper and lower transparent electrodes 13, 3, that is, a region portion indicated by A in the drawing is a portion indicating display, and is a region portion indicating one display pixel.

  FIG. 12 is a cross-sectional view of a main part in which a backlight is disposed below the liquid crystal display element 20. In general, a backlight is provided below the liquid crystal display device. A transflective plate 21 is disposed on the lower surface side of the liquid crystal display device 20, a diffusion plate 22 is disposed under the transflective plate 21, and a light guide plate 23 is disposed thereunder. The light guide plate 23 is provided with a reflection plate 24. An illumination light source 25 is disposed on the side surface of the light guide plate 23. Here, the light guide plate 23 provided with the diffusion plate 22 and the reflection plate 24 and the light source 25 constitute a backlight device 26.

  The light from the light source 25 is guided to the back by the light guide plate 23, the light is emitted above the light guide plate 23 by the reflection plate 24, and the light is diffused by the diffusion plate 22 and transmitted through the transflective reflection plate 21. The light that has passed through the transflective plate 21 passes through the region of the liquid crystal molecules 17b of the liquid crystal display device 20, that is, the portion of the display pixel A, and is emitted outside. As a result, the display is viewed brightly.

  However, the configuration of the conventional liquid crystal display device described above has a narrow viewing angle, and when the display portion is at the center, the range of ± 45 ° within the upper, lower, left, and right is within the range where the display can be confirmed. Therefore, when the display is viewed at a position deviating from that, there is a problem that the display cannot be visually recognized well.

  In order to widen the range in which this display can be confirmed, various techniques have been reported in the past as techniques for widening the viewing angle. As one of them, the technical disclosure of Patent Document 1 below can be seen.

JP-A-9-152606

  Here, the technique for widening the viewing angle disclosed in Patent Document 1 will be briefly described with reference to FIG. FIG. 13 shows a side view of a liquid crystal display device having a backlight as disclosed in Patent Document 1. From FIG. 13, the liquid crystal display device includes a liquid crystal display element 40, a backlight 30 disposed behind the liquid crystal display element 40, and a diffusion plate 50 provided on the surface of the liquid crystal display element 40. . Here, the backlight 30 includes a light guide plate 32, a prism sheet 34 affixed on the light guide plate 32, a light source lamp 33, and a case 3 provided so as to cover them. The light guide plate 32 is provided with V-shaped grooves 32a on the bottom surface with gradually decreasing pitches toward the center. The prism sheet 34 has a fine width prism portion 34a along a direction orthogonal to a plane including the normal line H and the viewing angle direction F of the liquid crystal display element 40, that is, a direction parallel to the V-shaped groove of the light guide plate 32. It is provided in a straight line. The liquid crystal display element 40 is formed by attaching polarizing plates 43 and 44 to upper and lower surfaces of a liquid crystal cell 41 in which transparent electrodes and alignment films are provided on upper and lower substrates 42a and 42b and liquid crystal is sealed. The diffuser plate 50 is attached to the polarizing plate 43, but the scattering rate of light incident along the incident surface parallel to the predetermined direction increases with the inclination angle from the normal of the incident surface. The optical film has a diffusion characteristic having a change range that increases, and a scattering incident angle range including an incident angle range corresponding to the change range of the scattering rate is set to a predetermined angle. That is, the diffusing plate 50 has directivity in the diffusion characteristics of transmitted light, and light along a plane that includes the normal line of the diffusing plate and is orthogonal to a specific direction is transmitted with a high transmittance. The light transmitted along the surface inclined in the direction perpendicular to the angle is scattered at a scattering rate corresponding to the incident angle. In the liquid crystal display device, it is desirable to set the scattering incident angle range to 15 ° to 45 °.

  However, the configuration in which the diffusion plate is provided has a problem that the viewing angle is widened but is not extremely widened. Further, since the viewing angle is widened by using scattered light, a display image is blurred. Further, an angle of about 140 ° is desired as an enlarged viewing angle.

  An object of the present invention is to display an image with high contrast and to dramatically widen the viewing angle. As a means for achieving this object, the invention described in claim 1 is a liquid crystal display device in which liquid crystal is sealed between upper and lower substrates each having a transparent electrode on each inner surface, and the transparent electrode on the upper substrate and the lower electrode on the lower substrate. A plurality of openings made of small holes are provided in at least one of the transparent electrode of the upper substrate or the transparent electrode of the lower substrate where the transparent electrode of the substrate is opposed to form the display pixel region. It is what.

  The invention described in claim 2 is characterized in that the shape of the opening formed by the small holes is a circular shape or a polygonal shape.

  The invention according to claim 3 is characterized in that the size of the opening formed of the small holes is in the range of 4-30 μm in the minor axis and the major axis.

  According to a fourth aspect of the present invention, the total area of the plurality of openings is 10 to 70% with respect to the area of the display pixel region.

  The invention according to claim 5 is characterized in that the plurality of openings are formed in the same shape, the same size, and at equal intervals.

  The invention described in claim 6 is characterized in that the size of the plurality of openings increases toward the outer periphery of the display pixel region.

  The invention described in claim 7 is characterized in that there are a plurality of display pixel regions, and all the display pixel regions have openings with the same pattern pattern.

  According to the eighth aspect of the present invention, when a plurality of openings made of small holes are provided in both the transparent electrode of the upper substrate and the transparent electrode of the lower substrate where the display pixel region is formed, the upper substrate The opening on the side and the opening on the lower substrate side do not overlap each other.

  When the liquid crystal has a positive dielectric anisotropy, at least one of the transparent pixel portions of the upper and lower substrates facing each other, that is, the display pixel region portion where the upper and lower transparent electrodes are opposed to form a display image is transparent. When an opening made of very small holes is provided in the electrode, when a voltage is applied to the upper and lower transparent electrodes, no voltage is applied to the surface where the small holes are provided, so that the electric field strength in the vicinity of the surface of the small holes becomes weak. Since the liquid crystal molecules are oriented toward the direction where the electric field strength is strong, if there is a portion where the electric field strength is weak, the liquid crystal molecules in that portion show a tilted orientation. Accordingly, the liquid crystal molecules in that portion stand up with an inclination. That is, the liquid crystal molecules in the vicinity where the openings are provided show an inclined alignment. For this reason, since the light travels along the alignment direction in which the liquid crystal molecules are inclined, the light is dispersed therein, and the dispersed light is emitted from the liquid crystal display device. Thereby, an emission angle becomes wide and a viewing angle becomes wide. Here, the shape of the opening is preferably circular or polygonal. The liquid crystal molecules in the electric field rise up step by step while rotating from the lying state. If the boundary where the electric field is cut off is circular, the rise of liquid crystal molecules can be continuously connected. Therefore, light can be efficiently guided around the circle from the central portion of the opposite side of the surface having the circular hole. Circular shapes include round, oval, oval and the like. In the case of a polygonal shape, a polygonal shape having a large number of corners that is particularly close to a circle is more desirable. At the corners, the rise of liquid crystal molecules is not continuous, and light having a large inclination cannot be efficiently guided. For this reason, the greater the angle of the corner, the more continuity can be ensured, and the efficiency of guiding light with inclination is improved. Further, since the direction of rubbing is different from that of the straight line, the inclination of the liquid crystal molecules in each straight line portion appears differently. This appears as a difference in viewing angle depending on the viewing location. It also becomes a cause of color unevenness. This difference in the directionality of the inclination appears remarkably in polygons with a small number of corners, that is, triangles and quadrangles, and becomes smaller as the polygons with a large number of corners, that is, polygons close to a circle. In the case of a polygon, a stable viewing angle can be obtained by designing the orientation tilt of the liquid crystal molecules so as to have a uniform direction as much as possible. Further, variations such as color unevenness become very small. It is preferable to select a hexagonal shape or more as the polygonal shape.

  Moreover, in this invention, the magnitude | size of an opening part is controlled to 4-30 micrometers. As a result, the viewing angle is widened up to a maximum of 70 ° on one side (140 ° as the combined left and right angles). The viewing angle of 70 ° on one side is within the viewing angle range where the display can be clearly seen from almost any position. If the size of the opening is smaller than 4 μm, the viewing angle is not much different from the conventional viewing angle, and the effect of wide viewing angle does not appear. On the other hand, if it is larger than 30 μm, a remarkable effect of a wide viewing angle can be obtained, but a color shift appears in the case of color display. In the case of black and white display, the roughness becomes conspicuous, and the contrast between white and black becomes worse. A size of 4 to 30 μm is selected as a suitable size of the opening.

  Further, the total area of the plurality of openings is restricted to 10 to 70% with respect to the area of the display pixel region. When the area is less than 10%, the effect of wide viewing angle does not appear remarkably. On the other hand, if it exceeds 70%, the electrode area is reduced, the amount of transmitted light toward the front is reduced, and the display image becomes dark and difficult to view.

  In addition, when a plurality of openings are formed in the same shape, the same size, and at equal intervals, the brightness of the display image also appears uniformly. In addition, since the tilt angles of the liquid crystal molecules are the same, the same viewing angle can be obtained.

  Further, if the opening is formed larger as it goes to the outer periphery of the display pixel region, the rising angle of the liquid crystal molecules becomes smaller as it goes to the outer periphery. As a result, the tilt angle of the light is increased, and a large amount of light having a large tilt angle is emitted to the outside, thereby widening the viewing angle. Even in a perspective state, the outline of the pattern becomes clear and identification is possible.

  Further, if any display pixel region has openings with the same pattern, a display image having the same viewing angle and the same brightness is obtained on the entire screen, and the uniformity of the display image appears.

  Further, when the openings are provided in both the transparent electrode on the upper substrate and the transparent electrode on the lower substrate, the openings on the upper substrate side and the openings on the lower substrate side are provided so as not to overlap each other. When the openings overlap, liquid crystal molecules do not stand up and light does not pass through the overlapped portions. Accordingly, the brightness is lowered because the light utilization efficiency is lowered.

  The best mode for carrying out the present invention will be described below with reference to FIGS. 1 and 2 show only one of many display pixel areas, FIG. 1 is a plan view showing one display pixel area, and FIG. 2 is a cross-sectional view of the main part in FIG. The explanatory view explaining the transmissive state of light in is shown. 1 and 2, the display pixel region A has a square shape, and an upper transparent electrode 73 (also referred to as a segment electrode) formed on the lower surface of the upper transparent substrate 72 and a lower transparent substrate 62. A region sandwiched between lower transparent electrodes 63 (also referred to as common electrodes) formed over the entire upper surface forms a display pixel region A for displaying an image. Accordingly, a portion where the upper transparent electrode 73 is formed appears as a display pixel region. The upper transparent electrode 73 and the lower transparent electrode 63 have a structure in which alignment films 74 and 64 subjected to rubbing treatment are provided on the upper surfaces, respectively, and liquid crystal 77 is sealed between the alignment films 74 and 64. taking it. A polarizing plate provided outside the upper and lower transparent substrates 72 and 62 is not shown.

  The upper transparent electrode 73 is provided with a plurality of openings 73a each having a round circular small hole. All the openings 73a have the same size and are arranged at equal intervals. The gap amount (gap amount) for enclosing the liquid crystal 77 is set in the range of 2 to 10 μm, and the TN (twisted nematic) type liquid crystal is used as the encapsulated liquid crystal 77. A voltage of 5 to 15 V is generally applied to the liquid crystal 77 in the display pixel region A via the upper and lower transparent electrodes 73 and 63.

  When the liquid crystal has positive dielectric anisotropy, it shows a lying state when no voltage is applied, and rises when a voltage is applied from above and below. When a required voltage is applied to the upper and lower transparent electrodes 73 and 63, the upper transparent electrode 73 does not generate an electric field in the portion where the opening 73a made of a small hole is formed, and generates a strong electric field in the portion where the electrode is formed. To do. On the other hand, the lower transparent electrode 63 generates a strong electric field over the entire surface. Therefore, as shown in FIG. 2, the liquid crystal molecules 77c in the region of the opening 73a at the portion where the upper transparent electrode 73 is formed stand up with the liquid crystal molecules tilted toward the surface where the electrode is located. . In addition, the liquid crystal molecules 77b in the portion without the opening 73a are oriented toward both electrodes and stand up. In the portion where the upper transparent electrode 73 is not formed, the liquid crystal molecules 77a are in a lying state.

  As a result, in the portion where the liquid crystal molecules 77c are inclined, the light transmitted therebends and travels along the inclined direction of the liquid crystal molecules 77c (lights L1, L2, L3, L4, L5, L6), and the liquid crystal molecules In the portion where 77b stands, the light passing therethrough travels between the standing liquid crystal molecules 77b. On the other hand, the portion where the liquid crystal molecules 77a are lying does not transmit light. As can be seen from FIG. 2, the lights L1, L2, L5, and L6 are light traveling along the tilted liquid crystal molecules 77c, and have an emission angle tilted along the tilt of the liquid crystal molecules. Thus, the viewing angle is expanded by the appearance of the light inclination angle α.

  The inclination angle α of the light is affected by the size of the opening 73a made of a small hole and the gap amount between both electrodes (upper and lower transparent electrodes 73 and 63). In the present invention, since the gap amount of the liquid crystal display device is 2 to 10 μm, the size of the opening 73a is set to 4 to 30 μm. FIG. 3 is an explanatory diagram used for setting the size of the opening 73a. FIG. 3A shows a case where the inclination angle α of the light is large, and FIG. The case where the light inclination angle α is small is shown. In general, when there are no openings in the upper and lower transparent electrodes, the inclination angle of light (viewing angle on one side) is 30 ° ± 15 ° (60 ° ± 30 ° when both sides are combined). That is, it has a light inclination angle of 45 ° at one side. Therefore, in order to widen the viewing angle, it is necessary to set the tilt angle of light to 45 ° or more. The viewing angle is determined by the tilt angle of the light, and the viewing angle is set in a state almost equal to the tilt angle of the light. Therefore, the viewing angle can be widened by increasing the tilt angle of the light. 3A shows a case where the light tilt angle is set to 55 °, and FIG. 3B shows a case where the light tilt angle is set to 45 °. Here, since the light inclination angle 55 ° has a variation of ± 15 ° on one side at a viewing angle of 55 ° on one side (110 ° viewing angle on both right and left sides), the viewing angle on one side is max 70 ° ( A maximum angle of max 140 ° on both the left and right sides is obtained. If the viewing angle on one side is within a range of 70 ° max, the visibility of the display image is not affected. On the other hand, when the light tilt angle is 45 °, a maximum viewing angle can be obtained in a normal liquid crystal display device. In the present invention, the objective is to obtain a viewing angle equal to or larger than the normally obtained max viewing angle, and therefore, the light inclination angle is set to 45 ° as min.

  In FIG. 3A, G indicates the gap amount between the upper transparent electrode 73 and the lower transparent electrode 63, and a numerical value of 2 to 10 μm is given. D indicates the size of the opening 73 a formed by a small hole in the upper transparent electrode 73. r indicates 1/2 of the size D of the opening 73a, and D = 2r. Lm represents a gradient line with a light inclination angle of 55 °. 3 (a) is an explanatory diagram for obtaining the size of the opening 73a of the small hole of the upper transparent electrode 73, the components that do not affect the size of the opening 73a are omitted. It is. Here, from FIG. 3A, the size D of the opening 73a is given by D = 2r, but since r = Gtan55 °, it is given by D = 2Gtan55 °. Therefore, when G = 2 μm, a size of D≈6 μm is obtained, and when G = 10 μm, a size of D≈30 μm is obtained. For this reason, the size D of the opening 73a can be allowed up to 30 μm at the maximum to make the light inclination angle 55 ° or less.

  Next, in FIG. 3B, Ln represents a gradient line with a light inclination angle of 45 °. G indicates the gap amount between the upper transparent electrode 73 and the lower transparent electrode 63, and a numerical value of 2 to 10 μm is given. D indicates the size of the opening 73 a formed by a small hole in the upper transparent electrode 73. From FIG. 3B, the size D of the opening 73a is given by D = 2r, and since r = Gtan45 °, it is given by D = 2Gtan45 °. Therefore, when G = 2 μm, a size of D = 4 μm is obtained, and when G = 10 μm, a size of D = 20 μm is obtained. Therefore, the size D of the opening 73a can be allowed to be a minimum of 4 μm in order to make the light inclination angle 45 ° or more.

  From the above, by setting the size of the opening 73a in the range of 4 μm to 30 μm, the range of the viewing angle can be further increased from the normal range (one side 30 ° ± 15 °), and the maximum viewing field The angle can be expanded to a range of 140 °. Note that it is possible to further increase the viewing angle by further increasing the size of the opening 73a. However, when the size of the opening 73a becomes visible, a black dot appears and an appearance effect appears. Furthermore, in the case of a color image, color misalignment or the like starts to stand out, and in the case of a black and white image, the roughness is conspicuous and the influence of deterioration of the black and white contrast appears. If the size of the opening 73a is within the range of 30 μm, it is invisible to the eyes, so there is no effect on the appearance, and a viewing angle with no hindrance is obtained so that the display image can be viewed from any position. Visible clearly.

  Further, the total area of the opening 73a in the display pixel region A also affects the viewing angle and the brightness of the display image. In the present invention, the total area of the openings 73a is set as a preferable range of 10 to 70% with respect to the area of the display pixel region A. Table 1 shown below shows the visibility of the display image and the display image by changing the total area of the openings to the area of the display pixel region by forming round and circular openings at a uniform size of 30 μm. It is the table | surface which evaluated the brightness.

Here, the evaluation method is performed based on the following criteria.
Visibility of the display image: This is an evaluation based on subjective judgment as to whether or not the image can be viewed by looking at the display image from both the front direction and the direction inclined by 70 ° from the front. , X marks are not clearly visible as a whole in either direction. The sharpness of the ◯ mark decreased to such an extent that it was almost visible as a whole in either direction. The ◎ mark is clearly visible as a whole from both directions. Represents the evaluation.
Brightness of the display image: Evaluation based on subjective judgment as to whether the brightness of the display image when viewed from the front is sufficient. The x mark indicates that the display image is too dark and the image is clear. do not do. The Δ mark shows the image but lacks brightness. The mark ○ is bright enough to be evaluated, and the image can be clearly seen. The symbol ◎ is a brightness that does not cause any problems.

  From the above results, it was found that the range in which the total area of the openings 73a is 10 to 70% is a range having no problem in terms of visibility and brightness of the display image. And if the total area is less than 10%, although sufficient brightness can be obtained, the amount of light having an inclination angle generated by the opening is small, so that visibility in a wide viewing angle cannot be obtained sufficiently. found. It has also been found that if the total area is more than 70%, the displayed image lacks brightness, and satisfactory brightness cannot be obtained. Through the above evaluation experiment, it has been evaluated that 30% is preferable as the area of the more preferable opening.

  FIG. 4 is a plan view as an example showing the shape of the opening 73a. 4A shows a round shape, FIG. 4B shows an oval shape, FIG. 4C shows a regular octagonal shape, and FIG. 4D shows an elongated octagonal shape. As the shape of the opening 73a, a round circular shape shown in FIG. 4A, an oval shape shown in FIG. 4B, or a circular shape such as an elliptical shape (not shown). A shape is more preferable. If the opening 73a is circular, the liquid crystal molecules in the electric field rise from the lying state when a voltage is applied to the upper and lower transparent electrodes 73, 63, and gradually rise, but the electric field is cut off. When the boundary side is circular, the rise of liquid crystal molecules is continuously connected. Therefore, light can be efficiently guided from the central part of the opposite side of the surface having the circular hole around the entire circumference of the circle. Further, the shape of the opening is not only circular, but also a regular octagon shown in FIG. 4C and an elongated octagon shown in FIG. A polygonal shape may be used. In the case of a polygon, the rising of liquid crystal molecules is not continuous at the corners, and light with a large inclination to be guided cannot be efficiently guided with an inclination. Further, the inclination of the liquid crystal molecules at each straight line E appears with different directivity and inclination due to the difference between the rubbing direction and the straight line direction. This difference in the directionality of the inclination appears remarkably in a triangle or a quadrangle, and appears as a difference in viewing angle depending on the viewing location. It also becomes a cause of color unevenness. When the corner becomes a polygon with a large number of corners, that is, a polygon close to a circle, continuity can be secured at the rising edge of the liquid crystal molecules at the boundary where the electric field is cut off, and the inclination of The efficiency of light guiding is also improved. Therefore, a shape such as a triangle or a quadrangle should be avoided, and it is preferable to select a polygon that is at least a hexagon. From this, a stable viewing angle can be obtained by designing the alignment tilt of the liquid crystal molecules so as to have a uniform direction as much as possible.

  As described above, the size of the opening 73a is preferably in the range of 4 to 30 μm. Here, the size of the opening 73a will be described with reference to FIG. Since (a) in FIG. 4 shows a round circle, the size of the diameter a becomes the size of the opening. Since (b) in FIG. 4 shows an oval shape, the size of the opening is indicated by the short diameter b and the long diameter c. The minor axis b and the major axis c are within the range of 4 to 30 μm. Similarly, since FIG. 4C shows a regular octagon, the size of the opening is indicated by the short diameter d and the long diameter (diagonal line) e. Further, since FIG. 4D shows a long and narrow octagon, the short diameter f and the long diameter g indicate the size of the opening. Both the minor axis and the major axis are in the range of 4 to 30 μm.

  The openings 73a of the present embodiment are round and circular in shape, are the same size, and are formed at the same intervals. When openings having the same shape, the same size, and the same interval are provided, unevenness and the like are reduced in transmitted / radiated light quantity, so that a good black and white contrast appears. Further, the same viewing angle can be obtained from any direction with respect to the display image. Therefore, it is most preferable that the openings are provided in the same shape, the same size, and the same interval. However, it does not particularly stick to the same shape, the same size, and the same interval. As for the shape, a round shape or an oval shape may be mixed. In the case of an oval shape, it is efficient to align the major axis with the alignment direction of the alignment film. Also, various sizes may be mixed in the range of 4 to 30 μm.

  The arrangement of the openings 73a may be a random arrangement. In any case, it is only necessary to have an arrangement interval that does not cause color unevenness or contrast failure in the color image.

  Embodiments of the present invention will be described below with reference to FIGS. Here, the illustration will be briefly described. FIG. 5 is a plan view of the main part of the liquid crystal display device according to the first embodiment of the present invention, and FIG. 6 is a cross-sectional view of the main part of the liquid crystal display device in FIG. FIG. 7 is a plan view of a liquid crystal display device drawn out of only one display pixel region of the liquid crystal display device according to the second embodiment of the present invention, and FIG. 8 is a cross-sectional view of the main part of the display pixel region in FIG. Show. FIG. 9 is a plan view of the liquid crystal display device drawn out from only one display pixel region of the liquid crystal display device according to Embodiment 3 of the present invention, and FIG. 10 is a cross-sectional view of the main part of the display pixel region in FIG. The figure is shown.

  First, a liquid crystal display device according to Embodiment 1 of the present invention will be described with reference to FIGS. The liquid crystal display device 80 of the first embodiment is a simple matrix type liquid crystal display device. On the lower surface of the upper transparent substrate 92 made of glass, an upper transparent electrode 93 made of a plurality of ITO films in stripes (electrodes provided in parallel in the vertical direction in FIG. 5) is provided, while the lower transparent substrate 82 made of glass is provided. A lower transparent electrode 83 (an electrode provided in parallel in the horizontal direction in FIG. 5) is also provided on the upper surface in a stripe shape so as to intersect the upper transparent electrode 93 of the upper transparent substrate 92 at 90 degrees. ing. The upper transparent electrode 93 and the lower transparent electrode 83 intersect at 90 degrees, and the intersecting portion is the display pixel region A. The display pixel area A can display a color image, and is divided into a red display pixel area A (R), a blue display pixel area A (B), and a green display pixel area A (G). I know. Further, a black matrix 98 is provided between the display pixel areas A (R), A (B), and A (G), and the display pixel areas A (R), A (B), and A (G ) Is arranged in a matrix, and the black matrix 98 is arranged in a lattice shape. In addition, color filters 96R, 96B, and 96G made of red, blue, and green are predetermined on the lower surface of the upper transparent substrate 92 at the positions of the display pixel regions A (R), A (B), and A (G). It is provided in the pattern arranged. A color display image appears in the display pixel region A where the upper transparent electrode 93 and the lower transparent electrode 83 to which a voltage is applied intersect.

  Hereinafter, the configuration of the liquid crystal display device 80 of Embodiment 1 will be described with reference to FIG. In the liquid crystal display device 80, the upper substrate 91 and the lower substrate 81 are arranged to face each other, a fixed gap amount (set to 10 μm in this embodiment) is provided by the spacer 86, and the liquid crystal 87 is sealed between the gaps. The structure sealed with the material (not shown) is taken. The liquid crystal is a TN (twisted nematic) type liquid crystal. A polarizing plate 95 is provided on the outer surface of the upper substrate 91, and a transflective film 89 having both light transmission and reflection functions is provided on the outer surface of the lower substrate 81. 80. Further, a backlight 99 is disposed below the liquid crystal display device 80.

  The upper substrate 91 includes an upper transparent substrate 92 made of transparent glass having a thickness of 0.7 to 1.1 mm, and color filters 96R, 96B, and 96G made of red, blue, and green provided on the lower surface thereof according to a predetermined arrangement. The black matrix 98 provided in a lattice shape so as to partition the color filters 96R, 96B, 96G, the transparent protective film 97 provided flat on the color filters 96R, 96B, 96G, and the protective film 97 And an upper transparent electrode 93 made of a transparent ITO film and an alignment film 94 subjected to a rubbing process. As described above, the upper transparent electrode 93 is formed in a stripe shape, and a plurality of openings 93 a made up of elliptical small holes are arranged in each display pixel region A. ing.

  On the other hand, the lower substrate 81 includes a lower transparent substrate 82 made of transparent glass having a thickness of 0.7 to 1.1 mm, and a lower substrate made of an ITO film provided in a stripe shape with a predetermined width on the lower transparent substrate 82. It comprises a transparent electrode 83 and an alignment film 84 that has been rubbed.

  The backlight 99 has the same configuration as that described in the prior art. That is, the light guide plate provided with the reflection plate is disposed below the diffusion plate, and the light source is disposed on the side surface of the light guide plate. The light from the light source incident from the side surface of the light guide plate guides the light to the back of the light guide plate, reflects the light above the light guide plate with the reflection plate provided on the lower surface, and emits the light above the light guide plate. A structure is adopted in which light is diffused by a diffusion plate and incident on the transflective film 89 and the liquid crystal display device 80.

  Each component having the above-described configuration is as follows. The upper transparent substrate 92 and the lower transparent substrate 82 are made of transparent glass, and soda glass, quartz glass, borosilicate glass, normal plate glass, or the like is used as the glass. Since rigidity is required, a thickness of 0.7 to 1.1 mm is often selected. The black matrix 98 provided in a lattice shape is made of a chromium oxide (CrO) film, and is formed by a method such as a vacuum deposition method, a sputtering method, or a CVD method, and then an unnecessary portion is removed by a photolithographic method to finish a desired shape. . The color filters 96R, 96B, and 96G composed of red, blue, and green are formed by a screen printing method or the like by mixing red, blue, and green pigments with a resin such as a transparent acrylic resin. The transparent protective film 97 is provided for the purpose of protecting the color filter, the purpose of forming the upper transparent electrode 93 on a flat surface, etc. This is a printing method using a transparent acrylic resin, epoxy resin, urethane resin or the like. To form a flat surface. The upper transparent electrode 93 and the lower transparent electrode 83 are formed to a thickness of 500 to 600 mm by a method such as a vacuum deposition method, a sputtering method, or a CVD method using indium oxide ITO (Indium Tin Oxide) powder doped with tin. After that, it is finished in a stripe shape by a photomask and a photoetching method. The opening 93a provided in the upper transparent electrode 93 is formed together at this time. The alignment films 84 and 94 are finished by forming a thin film by a printing method or the like using a transparent polyimide resin or the like, and performing a rubbing process on the surface thereof. The polarizing plates 85 and 95 are produced by uniaxially stretching a polyvinyl alcohol film by a conventional method to form a polarizing film having a thickness of 20 μm, and a cellulose-based film having a thickness of 80 μm is pasted on both surfaces to form a 180 μm thickness. A polarizing plate is used. A semi-transmissive reflective film 89, which is a transparent film formed by thinly forming a highly reflective metal film such as aluminum or silver by vacuum deposition or the like, and has both light transmission and reflection functions. .

  Here, the plurality of openings 93a made of small holes provided in the upper transparent electrode 93 are formed in an elliptical shape in the first embodiment. The shape is not limited to an elliptical shape, and a round shape, an oval shape, or a polygon shape can be selected as described in the above embodiment. The size of the opening 93a is set so that the minor axis of the ellipse is 15 μm and the major axis is 30 μm. The arrangement of the openings 93a is set so that the total area of the openings 93a in the display pixel region A is 30% of the area of the display pixel region A, and the vertical and horizontal intervals are constant. Provided.

  When the liquid crystal has positive dielectric anisotropy, the liquid crystal molecules are lying sideways when no voltage is applied to the upper and lower transparent electrodes 93 and 83 or when only one of them is applied. Further, when a voltage is applied to both the upper and lower transparent electrodes 93 and 83, it stands upright. In the first embodiment, the upper transparent electrode 93 has an elliptical opening 93a having a minor axis of 15 μm and a major axis of 30 μm. Therefore, when a required voltage is applied to the upper and lower transparent electrodes 93 and 83, the liquid crystal molecules are aligned toward the surface of the upper transparent electrode 93 where the electrodes are removed except for the openings 93a. Accordingly, the liquid crystal molecules in the region of the opening 93a are oriented with an inclination, and the light transmitted there travels along the inclined orientation and is emitted out of the liquid crystal display device 80. As a result, a liquid crystal display device having a wide viewing angle and a wide viewing angle can be obtained. In the first embodiment, the opening 93a has an elliptical shape with a short diameter of 15 μm and a long diameter of 30 μm, and the total area of the opening 93a is 30% with respect to the area of the display pixel region A. was gotten.

  In Example 1, the opening 93a made of a small hole was formed in an elliptical shape, and an opening having a minor axis of 15 μm and a major axis of 30 μm was formed. The size of the opening affects the viewing angle, but the size is not limited to this value, and can be set as appropriate within the range of 4 to 30 μm as described in the above embodiment. it can. The total area of the opening 93a also affects the viewing angle. In the first embodiment, the total area of the openings 93a is set to 30% with respect to the area of the display pixel region A. However, the total area of the opening 93a is not limited to 30%, and can be appropriately set within a range of 10 to 70%.

  The liquid crystal display device 80 according to the first embodiment has three types of display, a red display pixel area A (R), a blue display pixel area A (B), and a green display pixel area A (G). A plurality of pixel regions A are provided. The openings 93a formed in the upper transparent electrodes 93 of the plurality of display pixel areas A are all formed in the same pattern pattern. That is, every display pixel region A is provided with an elliptical shape having the same size and the same arrangement interval. In this way, the same viewing angle can be obtained for any image in any display pixel region A, and an image having the same hue but a different color can be obtained. Then, a uniform image without variations for each display pixel region A is obtained.

  In the liquid crystal display device 80 according to the first embodiment, the upper transparent electrode 93 is provided with the small hole opening 93a. However, the small transparent hole 83 is provided on the lower transparent electrode 83 side. You can take different configurations.

  Further, the liquid crystal display device 80 according to the first embodiment is a simple matrix type liquid crystal display device in which the upper transparent electrode 93 and the lower transparent electrode 83 are respectively formed in a stripe shape, and they intersect at right angles. However, the present invention can be similarly applied to an active matrix type liquid crystal display device using TFT elements. The liquid crystal display device 80 of the first embodiment uses TN liquid crystal. Among liquid crystals, there are birefringence mode liquid crystals including STN (super twisted nematic) type liquid crystals, and it is known that when a voltage is applied to the liquid crystal in this mode, the color changes depending on the applied voltage and color display is possible. ing. The same applies to a liquid crystal using this mode.

  Next, a liquid crystal display device according to Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 7 is a plan view of a liquid crystal display device drawn out of only one display pixel region of the liquid crystal display device according to the second embodiment of the present invention, and FIG. 8 is a cross-sectional view of the main part of the display pixel region in FIG. Show. The liquid crystal display device shown here is a polymer dispersion type liquid crystal display device and does not use an alignment film or a polarizing plate. As shown in FIG. 8, the liquid crystal display device 100 has a configuration in which a lower substrate 101 and an upper substrate 111 are arranged to face each other with a certain gap, and a liquid crystal 107 is sealed in the gap. The lower substrate 101 is configured by providing a lower transparent electrode 103 made of an ITO film on an upper surface of a transparent lower transparent substrate 102 made of glass. The upper substrate 111 is configured by providing an upper transparent electrode 113 made of an ITO film on the lower surface of an upper transparent substrate 112 made of transparent glass. The upper transparent electrode 113 is provided for each display pixel region A, and the display pixel region A is formed by a region where the lower transparent electrode 103 and the upper transparent electrode 113 are opposed to each other. In addition, as shown in FIG. 7, the upper transparent electrode 113 in this embodiment forms an opening 113a composed of a plurality of very small round holes. The size of the opening 113a increases as it goes to the outer periphery of the display pixel region A. That is, the size of the opening 113a is small near the center of the display pixel region A, and the size is increased toward the outer periphery.

  The liquid crystal 107 uses polymer dispersed liquid crystal. In this polymer dispersed liquid crystal, liquid crystal fine particles of 0.5 to several μm are dispersed in a polymer material, which is in a state of light transmission (transparent) and light scattering (white turbidity) depending on the presence or absence of an electric field. Change between. Typical examples of such liquid crystals include DS mode liquid crystals, cholesteric mode liquid crystals, polymer dispersed liquid crystals, and smectic mode liquid crystals. In the second embodiment, PNLCD (polymer network liquid crystal) which is a polymer dispersed liquid crystal is used. This PNLCD is a mixed material of a polymer material (monomer) and a liquid crystal material (for example, nematic liquid crystal), and is a liquid crystal in which monomers are polymerized by ultraviolet irradiation to form a polymer network. It becomes transparent when a predetermined voltage is applied, and becomes cloudy when no voltage is applied. Since the liquid crystal material itself uses TN liquid crystal, when a voltage is applied to the upper and lower transparent electrodes, the liquid crystal molecules stand upright.

  As shown in FIG. 8, in the liquid crystal display device 100 having the above-described configuration, the size of the opening 113a increases toward the outer peripheral region of the display pixel region A, so that the liquid crystal molecules around the opening 113a are increased. Rises as the distance from the outer periphery of the display pixel region A decreases, and the inclination angle of the transmitted light increases toward the outer periphery of the display pixel region A. As a result, the inclination angle of light transmitted around the opening 113a is different between the central region and the outer peripheral region of the display pixel region A. Thereby, the display surface becomes small in a perspective state, but the outline of the pattern becomes clear and the pattern can be identified. By providing the opening 113a in multiple stages (for example, 10 μm, 20 μm, and 30 μm), there is no extreme change in the tilt angle of the light, so that the contour of the pattern can be recognized in a natural state and more clearly Can be identified. In addition, a uniform display image without color misregistration can be obtained.

  The size of the opening 113a is set in several steps from the range of 4 to 30 μm. It is preferable to provide the floors in as many floors as possible, but it is preferable to set them appropriately according to the size of the display pixel region A. Further, the total area of the opening 113a to be formed is set within a range of 10 to 70% with respect to the display pixel region A.

  In the second embodiment, the opening 113a is provided in a round circular shape. However, the opening 113a may be formed in an oval shape, an oval shape, a polygonal shape or the like within a range of 4 to 30 μm. good. In the second embodiment, the PNLCD is used for the description. However, the same effect can be obtained with a DS mode liquid crystal, a cholesteric mode liquid crystal, and a smectic mode liquid crystal.

  Next, a liquid crystal display device according to Embodiment 3 of the present invention will be described with reference to FIGS. FIG. 9 is a plan view of a liquid crystal display device drawn out from only one display pixel region of the liquid crystal display device according to Embodiment 3 of the present invention, and FIG. 10 is a cross-sectional view of the main part of the display pixel region in FIG. It is shown. The third embodiment will be described by taking up one display pixel region. Even a display pixel region having a large number of display pixel regions has the same configuration and structure. Accordingly, the same effect can be obtained in one display pixel region in other display pixel regions.

  As shown in FIGS. 9 and 10, the liquid crystal display device 120 of Example 3 is provided with openings 133 a and 123 a formed of elliptical small holes in both the upper transparent electrode 133 and the lower transparent electrode 123. In FIG. 9, an elliptical opening 133 a indicated by a solid line is an opening provided in the upper transparent electrode 133, and an elliptical opening 123 a indicated by a broken line indicates an opening provided in the lower transparent electrode 123. . They are provided at substantially equal intervals without overlapping each other. The long axis of the ellipse is more effective when matched to the rubbing direction. Therefore, in the case of a TN liquid crystal, it is efficient if the opening 133a and the opening 123a are oriented orthogonally. In the case of a PNLCD, the opening 133a and the opening 123a may be parallel.

  Further, the liquid crystal display device 120 of the third embodiment is different from the liquid crystal display device of the first embodiment described above, except for the upper transparent electrode 133 and the lower transparent electrode 123, the configuration and structure of the liquid crystal display device of the first embodiment. Has the same structure and structure. That is, the liquid crystal display device 120 has a configuration in which the upper substrate 131 and the lower substrate 121 are arranged to face each other, a certain gap amount is provided via a spacer, and the liquid crystal 127 is sealed with a sealing material between the gaps. Is taking. The liquid crystal is a TN (twisted nematic) type liquid crystal. A polarizing plate 135 is provided on the outer surface of the upper substrate 131, and a transflective film 128 having both light transmission and reflection functions is provided on the outer surface of the lower substrate 121, thereby providing a liquid crystal display device. 120 is configured. Further, a backlight 129 is disposed below the liquid crystal display device 120.

  The upper substrate 131 includes an upper transparent substrate 132 made of transparent glass having a thickness of 0.7 to 1.1 mm, a color filter 136 made of red, blue, and green provided on the lower surface thereof according to a predetermined arrangement, and these three colors. A black matrix 138 provided in a lattice shape so as to partition each of the color filters 136, a transparent protective film 137 provided flat on the color filter 136, and a transparent ITO film provided on the protective film 137 The upper transparent electrode 133 and the alignment film 134 subjected to the rubbing process. Further, the lower substrate 121 is subjected to a rubbing treatment with a lower transparent substrate 122 made of transparent glass having a thickness of 0.7 to 1.1 mm, a lower transparent electrode 123 made of an ITO film provided on the lower transparent substrate 122, and the like. The alignment film 124 is formed.

  Here, as shown in FIG. 9, the upper transparent electrode 133 is provided with an elliptical opening 133 a, and the lower transparent electrode 123 is similarly provided with an elliptical opening 123 a in the elliptical shape of the upper transparent electrode 133. The position is different from that of the opening 133a. The two components of the upper transparent electrode 133 and the lower transparent electrode 123 are different from the configuration of the first embodiment, and all other configurations are the same as those of the first embodiment. Moreover, the component of the same specification is used.

  As shown in FIGS. 9 and 10, the upper transparent electrode 133 and the lower transparent electrode 123 of the third embodiment have an elliptical opening 133 a having the same size in the horizontal direction and the vertical direction, respectively. It is provided with a certain interval. Similarly, the lower transparent electrode 123 is also provided with an elliptical opening 123a having the same size in the horizontal direction and the vertical direction with a certain interval between the opening 133a of the upper transparent electrode 133 and the lower transparent electrode 123. The electrode 123 is provided at a position where it does not overlap with the opening 123a.

  The display pixel area A is determined by the black matrix 138. In the display pixel region A, the upper transparent electrode 133 and the lower transparent electrode 123 face each other. Further, elliptical openings 133a and 123a as shown in FIG. 9 are provided on the faces facing each other. The openings 133a and 123a are provided at different positions without overlapping each other. The oval openings 133a and 123a are set in a size of 4 to 30 μm.

  When a predetermined voltage is applied to the upper transparent electrode 133 and the lower transparent electrode 123 provided without overlapping the openings 133a and 123a, the liquid crystal molecules 127c in the regions of the openings 133a and 123a are inclined as shown in FIG. Make your own way to stand up. Since the light from the backlight travels in the alignment direction having the inclination of the liquid crystal molecules 127c, the light bends and travels in the alignment portion having the inclination of the liquid crystal molecules 127c. That is, light travels with an inclination angle at that portion and is emitted toward the outside of the display pixel region A. By this action, the viewing angle of the display image is enlarged.

  If there is an overlap between the opening 133a of the upper transparent electrode 133 and the opening 123a of the lower transparent electrode 123, the liquid crystal molecules lie on the overlapping portion and light does not pass therethrough. For this reason, the light use efficiency decreases and the brightness decreases. This deteriorates the quality of the color display image in the display pixel region A. For this reason, the opening 133a of the upper transparent electrode 133 and the opening 123a of the lower transparent electrode 123 are designed not to overlap.

  The shape of the openings 133a and 123a is not particularly limited to the elliptical shape as described in the first embodiment. Round, oval, or polygonal shapes may be used. The size of the openings 133a and 123a is set in the range of 4 to 30 μm. Further, the total area of the opening 133a and the opening 123a is set as a total area of all the openings 133a and 123a and is within a range of 10 to 70% of the area of the display pixel region A. .

  The present invention has been described with reference to three embodiments. According to the present invention, by providing a very small opening (small hole) on at least one side of the upper transparent electrode or the lower transparent electrode, the viewing angle is dramatically increased without impairing the clarity of the display screen. Since it can be manufactured in the conventional process without increasing the number of components, the viewing angle can be increased without increasing the cost.

It is the top view which took out and drawn one display pixel area of the liquid crystal display device of the present invention. It is explanatory drawing explaining the permeation | transmission state of the light in the principal part cross section in FIG. FIGS. 3A and 3B are explanatory diagrams used to set the size of the opening. FIG. 3A shows a case where the light inclination angle α is large, and FIG. 3B shows a case where the light inclination angle α is small. The case where it took is shown. FIG. 4 (a) is a round circle, FIG. 4 (b) is an oval, FIG. 4 (c) is a regular octagon, and FIG. ) Shows an elongated octagonal shape. It is a principal part top view of the liquid crystal display device which concerns on Example 1 of this invention. It is principal part sectional drawing of the liquid crystal display device in FIG. It is a top view of the liquid crystal display device which extracted and extracted only one display pixel area | region of the liquid crystal display device which concerns on Example 2 of this invention. It is principal part sectional drawing of the display pixel area | region in FIG. It is a top view of the liquid crystal display device which extracted and extracted only one display pixel area | region of the liquid crystal display device which concerns on Example 3 of this invention. It is principal part sectional drawing of the display pixel area | region in FIG. It is principal part sectional drawing of the liquid crystal display device which takes the conventional very simple structure. It is principal part sectional drawing which has arrange | positioned the backlight under the liquid crystal display device. It is a side view of the liquid crystal display device provided with the backlight as shown by patent document 1. FIG.

Explanation of symbols

62, 82, 102, 122 Lower transparent substrate 63, 83, 103, 123 Lower transparent electrode 64, 74, 84, 94, 124, 134 Alignment film 72, 92, 112, 132 Upper transparent substrate 73, 93, 113, 133 Upper transparent electrodes 73a, 93a, 113a, 133a Openings 77, 87, 107, 127 Liquid crystals 80, 100, 120 Liquid crystal display devices 81, 101, 121 Lower substrates 85, 95, 125, 135 Polarizers 86 Spacers 89, 128 Half Transmission / reflection film 91, 111, 131 Upper substrate 96, 136 Color filter 97, 137 Protective film 98, 138 Black matrix 99, 129 Backlight A Display pixel area

Claims (8)

In a liquid crystal display device in which liquid crystal is sealed between upper and lower substrates each having a transparent electrode on each inner surface, the upper electrode and the lower substrate transparent electrode face each other to form a display pixel region. A liquid crystal display device comprising a plurality of openings each having a small hole in at least one of a transparent electrode of a substrate and a transparent electrode of a lower substrate. The liquid crystal display device according to claim 1, wherein a shape of the opening formed of the small holes is a circular shape or a polygonal shape. 3. The liquid crystal display device according to claim 1, wherein a size of the opening formed of the small holes is a size having a minor axis and a major axis in a range of 4 to 30 μm. 4. The liquid crystal display device according to claim 1, wherein a total area of the plurality of openings is 10 to 70% with respect to an area of the display pixel region. 5. The liquid crystal display device according to claim 1, wherein the plurality of openings are formed in the same shape, the same size, and at equal intervals. 5. The liquid crystal display device according to claim 1, wherein the plurality of openings have openings that increase in size toward the outer periphery of the display pixel region. 7. The liquid crystal display device according to claim 1, wherein the display pixel region includes a plurality of display pixel regions, and each of the display pixel regions forms an opening with the same pattern pattern. When a plurality of openings made of small holes are provided in both the transparent electrode on the upper substrate and the transparent electrode on the lower substrate where the display pixel region is to be formed, the opening on the upper substrate side and the opening on the lower substrate side The liquid crystal display device according to claim 1, wherein the portions do not overlap each other.

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