JP2012208277A - Liquid crystal display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystal display element allowing stereoscopic display without deteriorating display quality.SOLUTION: A liquid crystal display element 100 includes a pair of substrates 120 and 130 having a liquid crystal layer 110 interposed therebetween, and a pair of electrodes 121 and 131 provided on inner surfaces of the substrates 120 and 130, respectively and applying an electric field to the liquid crystal layer 110. A plurality of openings 124 and 134 are formed in a part of or the entire region of each of the electrodes 121 and 131. The pitch of the openings 124 and 134 is 75 μm or more and 150 μm or less.

Description

  The present invention relates to a segment display type liquid crystal display element.

  Conventionally, a segment display type liquid crystal display element performs display by turning on and off display pixels, and is limited to planar display. On the other hand, Patent Document 1 discloses a technique in which the first and second segment electrodes whose width changes in a step shape are arranged in a comb shape and the display color is changed to obtain a stereoscopic display effect. . Patent Document 2 discloses a technique in which a small opening is provided in a part of the electrode (sub-segment electrode) to express the light and shade by the outline of the segment and display with more stereoscopic effect.

Japanese Patent Laid-Open No. 5-34705 JP 2001-201755 A

  However, in the method of forming a minute opening in a part of the electrode disclosed in Patent Document 2, if the size of the opening is too small, the liquid crystal orientation cannot be controlled when the display is about 10% thin. On the other hand, if it is too large, uneven light emission is conspicuous in the segment, and there is a problem that the display quality is lowered depending on the size of the opening.

  Accordingly, an object of the present invention is to provide a liquid crystal display element capable of three-dimensional display without deteriorating display quality.

  In order to solve the above problems, the present invention includes a pair of substrates that sandwich a liquid crystal layer, and a pair of electrodes that are respectively formed on the inner surface of the substrate and that apply an electric field to the liquid crystal layer. In the liquid crystal display element, a plurality of openings are formed in a partial region or the entire region of each electrode, and the pitch of the openings is 75 μm or more and 150 μm or less.

  According to the present invention, a three-dimensional display is possible without degrading display quality.

The front view of the liquid crystal display element which is embodiment of this invention. The fragmentary sectional view of a liquid crystal display element same as the above. The partial perspective view which shows the light-and-dark part of the transparent electrode of a liquid crystal display element same as the above. The figure which shows the evaluation result of a liquid crystal display element same as the above.

  An embodiment in which the present invention is applied to a segment display type liquid crystal display element will be described below with reference to FIGS. In addition, this invention is not limited by the following embodiment and drawing. It goes without saying that changes (including deletion or addition of components) can be added to the following embodiments (including the aspects described in the drawings).

  As shown in FIGS. 1 and 2, the liquid crystal display element 100 includes a liquid crystal layer 110, an upper substrate 120, and a lower substrate 130. A polarizing plate (not shown) is provided outside the upper and lower substrates 120 and 130, respectively.

  The liquid crystal layer 110 is composed of liquid crystal including liquid crystal molecules sandwiched between the upper substrate 120 and the lower substrate 130. The upper substrate 120 and the lower substrate 130 are overlapped and fixed so as to face each other with a predetermined distance between them with a sealing member (not shown) interposed therebetween. A sealed space is formed by the upper substrate 120, the lower substrate 130, and the sealing member, and the liquid crystal is confined in the formed sealed space. A method of confining the liquid crystal can be performed by a known method. The liquid crystal confined in the sealed space constitutes a liquid crystal layer 110. The liquid crystal is made of, for example, a liquid crystal material having a negative dielectric anisotropy characteristic.

  The upper substrate 120 is a transparent substrate (for example, a transparent glass substrate) that transmits light, and a transparent electrode 121 having a predetermined shape that forms the display unit 190 is formed on the inner surface, that is, the surface facing the lower substrate 130. . The transparent electrode 121 is formed by a known method (for example, sputtering, vapor deposition, or etching). On the upper substrate 120, an insulating film (not shown) is formed so as to cover the transparent electrode 121, and an alignment film (not shown) is formed on the insulating film so as to cover the insulating film. Each of the insulating film and the alignment film is formed by a known method (for example, flexographic printing).

  The transparent electrode 121 is made of, for example, ITO (indium tin oxide) that transmits light. Details of the transparent electrode 121 will be described later.

  The lower substrate 130 has substantially the same configuration as the upper substrate 120 and is a transparent substrate corresponding to the upper substrate 120. A transparent electrode 131 corresponding to the transparent electrode 121 is formed on the inner surface of the lower mold substrate 130, that is, on the surface facing the upper substrate 120. The lower substrate 130 includes an insulating film and an alignment film (not shown), and corresponds to the insulating film and the alignment film provided on the upper substrate 120.

  A plurality of transparent electrodes 121 and 131 are formed in a desired shape. One or more transparent electrodes 121 and 131 may be formed. The transparent electrodes 121 and the transparent electrodes 131 facing each other have substantially the same planar shape (the shape viewed from the thickness direction of the liquid crystal layer 110). In the display surface of the liquid crystal display element 100, a region corresponding to a portion where the plurality of transparent electrodes 121 and the plurality of transparent electrodes 131 are opposed to each other is a display unit 190 on which the liquid crystal display element 100 displays a display pattern. That is, the display unit 190 is formed by the plurality of transparent electrodes 121 and the plurality of transparent electrodes 131.

  Each of the transparent electrodes 121 and 131 is composed of monochrome electrode portions 122 and 132 constituting a segment 191 described later and gray scale electrode portions 123 and 133 constituting a gray scale portion 192 described later. The monochrome electrode parts 122 and 132 are formed in a shape corresponding to the segment 191, and ITO is formed in all areas. The gray scale electrode parts 123 and 133 are located on the periphery of the monochrome electrode parts 122 and 132, and are formed in a shape corresponding to a part of the outline of the monochrome electrode parts 122 and 132. A part is removed, and minute openings 124 and 134 are provided. By partially removing the ITO, the gray scale portion 192 has a location where the orientation of the liquid crystal is controlled by on / off of voltage application depending on the presence or absence of the ITO (that is, a location where light can be transmitted) and the orientation of the liquid crystal. Uncontrolled locations (i.e., locations where light is not transmitted) occur, resulting in a lighter grayscale than the segment 191. The liquid crystal display element 100 can obtain a three-dimensional display pattern as compared with the display of only the segment 191 by expressing the shade by the gray scale portion 192 and enhancing the outline of the segment 191. When the background of the display unit 190 is black and the segment 191 is displayed in white, the gray scale unit 192 is displayed in gray whose white is lighter than the segment 191. The gray scale can be adjusted by changing the aperture ratio (ratio of the area of the opening to the predetermined unit area of the electrode section) in the gray scale electrode sections 123 and 133, and the aperture ratio is gradually changed. By doing so, it is also possible to change gradation of gradation and express gradation. FIG. 3 shows a specific example of forming the openings 124 and 134 in the gray scale electrode parts 123 and 133. The gray scale electrode parts 123 and 133 are designed so that the openings 124 and 134 are formed by removing a part of the ITO. Here, in order to eliminate the influence of the oblique electric field, the locations where the openings 124 and 134 are formed are preferably the same in the gray scale electrode portions 123 and 134 and the openings 124 and 134 are opposed to each other. The shapes of the openings 124 and 134 may be a circle or a triangle in addition to the rectangle shown in FIG. Further, as a result of intensive studies by the inventor of the present application, the alignment of the liquid crystal is favorably controlled in the gray scale electrode portions 123 and 133, and the light emission unevenness due to the openings 124 and 134 is not conspicuous. The pitch (width) W (in this embodiment, the distance between the end portions of adjacent openings) is 75 μm or more and 150 μm or less (more desirably 75 μm or more and 100 μm or less). The size of the openings 124 and 134 is arbitrarily determined by the pitch W and the opening ratio of the openings 124 and 134. When the openings 124 and 134 are formed in a square shape, for example, the length of one side Is formed with a thickness of about 5 μm to 140 μm.

  Returning to FIG. 1, the liquid crystal display element 100 displays a display pattern in a so-called segment display. That is, the display unit 190 for displaying the display pattern includes a plurality of segments 191 and a plurality of gray scale units 192 having a shape corresponding to a part of the outline of the segment 191. One segment 191 is composed of one monochrome electrode part 122 and one monochrome electrode part 132, and one grayscale part 192 is composed of one grayscale electrode part 123 and one grayscale electrode part 133. Is done. The liquid crystal display element 100 emits light that has passed through one or more segments 191 and the contour portion 192 selected from the plurality of segments 191 and the gray scale portion 192 (that is, the segment 191 and the contour portion 192 are output). By lighting up, a plurality of types of display patterns (for example, the numbers “0” to “9”) can be displayed. As described above, the gray scale portion 192 displays lighter than the segment 191. In order to turn on the segment 191 and the gray scale portion 192, a voltage may be applied between the transparent electrodes 121 and 132 corresponding to the desired segment 191 and gray scale portion 192. The segment part 191 and the gray scale part 192 corresponding to the segment part 191 may be connected to the same wiring and may be turned on / off in synchronization, or may be connected to separate wirings and individually switched on / off. good. Further, the formation portion of the gray scale portion 192 is arbitrary, and is not limited to the outline of the segment 191, but may be a part of the segment 191.

FIG. 4 shows a display state and a microscopic confirmation result when the pitch W of the openings 124 and 134 is set to 50 μm, 75 μm, 100 μm, and 150 μm in the liquid crystal display element 100 described above. The evaluation results of the orientation and emission unevenness are shown. In the liquid crystal display element 100 that has been evaluated, the gray scale ratio (the electrode portion of the electrode portion) is added to the fan-shaped segments 191 arranged in an arc shape and a part of the substantially rectangular segments 191 constituting the number “188”. Gray scale portions 192 were formed in which the ratio of the area of ITO to a predetermined unit area was 80%, 60%, 40%, 20%, and 10%, respectively. As a result, when the pitch W of the openings 124 and 134 is set to 100 μm, the alignment of the liquid crystal is stable, the light emission unevenness is not visually recognized in each gray scale portion 192, and the boundary between the gray scale portions 192 is not conspicuous. . In contrast, when the pitch W of the openings 124 and 134 is reduced, the orientation of the liquid crystal becomes gradually unstable. At 75 μm, the orientation of the liquid crystal is relatively stable, but when it is 50 μm, the gray scale ratio is particularly 10%. In the gray scale portion 192, a region to which an oblique electric field is applied becomes large, and the alignment of the liquid crystal becomes unstable, so that a good display cannot be obtained. In addition, when the pitch W of the openings 124 and 134 is increased, the size of the openings 124 and 134 is increased, and light emission unevenness is visually recognized in each gray scale portion 192 at 150 μm, and the boundaries between the gray scale portions 192 having different gray scale ratios. Has become conspicuous. Therefore, it is considered that the degree of light emission unevenness of the gray scale portion 192 exceeds the allowable range on the product when the pitch W of the openings 124 and 134 is larger than 150 μm.

  As described above, in the liquid crystal display element 100 according to the present embodiment, a plurality of minute openings 124 and 134 are formed in a partial region or all regions of the transparent electrodes 121 and 131, and the openings 124 and 134. By setting the pitch W to 75 μm or more and 150 μm or less (more desirably 75 μm or more and 100 μm or less), a three-dimensional display can be achieved by expressing light and shade without reducing display quality.

  The present invention is suitable for a segment display type liquid crystal display element.

DESCRIPTION OF SYMBOLS 100 Liquid crystal display element 110 Liquid crystal layer 120 Upper side substrate 121 Transparent electrode 122 Monochrome electrode part 123 Gray scale electrode part 124 Opening part 130 Lower side substrate 131 Transparent electrode 132 Monochrome electrode part 133 Gray scale electrode part 134 Opening part 190 Display part 191 Segment 192 Gray scale part

Claims (2)

A liquid crystal display element comprising: a pair of substrates sandwiching a liquid crystal layer; and a pair of electrodes formed on the inner surface of the substrate for applying an electric field to the liquid crystal layer, A liquid crystal display element, wherein a plurality of openings are formed in a partial region or all regions, and a pitch of the openings is 75 μm or more and 150 μm or less. The liquid crystal display element according to claim 1, wherein the pitch of the openings is 75 μm or more and 100 μm or less.

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