JP2018132566A - Display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a display that has a new structure.SOLUTION: A display comprises: an LCD element 10 that displays a desired pattern; a cover member 52 that is arranged on a display surface of a display device and has a curved plate-like shape; and a light guide member 60 that is arranged between the LCD element 10 and cover member 52 in close adhesion with both the LCD element 10 and cover member 52.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a display device, particularly a liquid crystal display device.

  In general, a liquid crystal display device includes a light source, a liquid crystal cell, and a polarizing plate. In products using a liquid crystal display device, a protective member or a cover member is often provided on the display surface side of the liquid crystal display device (for example, Patent Documents 1 and 2). In some cases, the surface of the protective member or cover member is a curved surface in order to improve appearance quality and optical characteristics (for example, Patent Documents 3 and 4).

JP-A-7-1114010 Japanese Patent Laid-Open No. 8-043784 JP 2002-202410 A JP 2007-178646 A

  A main object of the present invention is to provide a display device having a novel structure.

  According to a main aspect of the present invention, a display device that displays a desired pattern, a translucent resin member that is disposed on a display surface side of the display device and has a curved plate shape, and the display device There is provided a display device having a light guide member disposed in close contact with both the display device and the light transmissive resin member between the light transmissive resin member.

  A display device having a novel structure is provided.

It is sectional drawing which shows a 1st liquid crystal display device. It is sectional drawing which shows a 2nd liquid crystal display device. 3A and 3B are cross-sectional views showing a third liquid crystal display device and a modified version thereof. FIG. 4A is a cross-sectional view showing a fourth liquid crystal display device, and FIG. 4B is a graph showing the dependence of the light transmittance on the inclination angle (observation angle) in the liquid crystal display element constituting the fourth liquid crystal display device. It is a top view which illustrates the electrode pattern of the liquid crystal cell by an Example.

  FIG. 1 is a cross-sectional view showing the basic structure of the first liquid crystal display device 101. Note that the relative sizes and positional relationships of the constituent members shown in the drawing are different from the actual ones.

  The first liquid crystal display device 101 includes a liquid crystal display element (LCD element) 10, a light source 40 such as a fluorescent lamp or an LED light, and a cover member 51. The LCD element 10 and the light source 40 are accommodated in a predetermined casing, and the cover member 51 constitutes a part of the casing. Such a liquid crystal display device is used for, for example, a vehicle-mounted display that displays a speedometer, a fuel gauge, and the like.

  The LCD element 10 includes, for example, a vertical alignment type liquid crystal cell 20 and a pair of polarizing plates 31 and 32 disposed so as to sandwich the liquid crystal cell 20 therebetween. On the optical axis of the light source 40, one polarizing plate (back side polarizing plate) 31, the liquid crystal cell 20, the other polarizing plate (front side polarizing plate) 32, and the cover member 51 are arranged in order from the light source 40 side. The These components are usually provided in close contact with each other. In the LCD element 10, a surface opposite to the light source 40 (a surface away from the light source 40 or a surface on which the front polarizing plate 32 is disposed) may be referred to as a display surface of the LCD element.

  The liquid crystal cell 20 is, for example, a VA (vertical alignment) drive type liquid crystal cell having a segment type electrode structure. Note that, for example, an IPS (in-plane switching) driving type liquid crystal cell may be used. The liquid crystal cell 20 includes a lower substrate 21 and an upper substrate 22 that are disposed to face each other, and a liquid crystal layer 27 that is sandwiched between the lower substrate 21 and the upper substrate 22.

  The lower substrate 21 and the upper substrate 22 are transparent substrates such as a glass substrate and a plastic substrate, respectively. Specifically, a 0.7 mm thick soda lime glass substrate can be used.

  The lower substrate 21 and the upper substrate 22 are bonded to each other with a gap of, for example, 4 μm. The gap between the lower substrate 21 and the upper substrate 22 is held by rod-shaped or spherical spacers contained in a frame-shaped sealing material (not shown) and spherical spacers that are uniformly distributed in the substrate surface.

  A common electrode (solid electrode) 23 that is patterned so as to display a desired character, figure, or the like is provided on one surface side of the lower substrate 21 (the surface facing the upper substrate 22). On one surface side of the upper substrate 22 (on the surface facing the lower substrate 21), segment electrodes (display electrodes) 24 patterned in a planar shape such as desired characters and figures are provided. These electrodes 23 and 24 are formed by appropriately patterning a transparent conductive film such as indium tin oxide (ITO).

  A lower alignment film 25 is provided on one surface side of the lower substrate 21 so as to cover the common electrode 23. Similarly, an upper alignment film 26 is provided on one surface side of the upper substrate 22 so as to cover the segment electrode 24. As these alignment films 25 and 26, vertical alignment films that restrict the alignment state of the liquid crystal layer 27 to the vertical alignment (substrate normal direction) are used. Each alignment film is subjected to a uniaxial alignment process such as a rubbing process so as to be antiparallel to each other (directions of the uniaxial alignment process are indicated by arrows 25r and 26r in the figure).

  The liquid crystal layer 27 is provided between the lower substrate 21 and the upper substrate 22 so as to be surrounded by a frame-shaped sealing material (not shown). A liquid crystal member constituting the liquid crystal layer 27 is filled in a space defined by the lower substrate 21, the upper substrate 22, and a frame-shaped sealing material. As the liquid crystal material, for example, a negative liquid crystal material (birefringence Δn = 0.08, dielectric anisotropy Δε = −5.0) manufactured by Merck & Co. can be used.

  When no voltage is applied (light shielding state), the alignment direction of the liquid crystal molecules constituting the liquid crystal layer 27 is substantially perpendicular to the substrate surfaces of the lower substrate 21 and the upper substrate 22. The pretilt angle of the liquid crystal molecules is about 89.7 °. In the figure, the liquid crystal layer central liquid crystal molecule alignment direction is shown as an arrow 27d. When a voltage is applied (translucent state), the alignment direction of the liquid crystal molecules is substantially horizontal with respect to the substrate surfaces of the lower substrate 21 and the upper substrate 22.

  The pair of polarizing plates 31 and 32 are arranged so that their absorption axes are orthogonal to each other (crossed Nicols arrangement). Further, these absorption axes are arranged so as to be inclined by approximately 45 ° with respect to the liquid crystal molecule alignment direction of the liquid crystal cell 20.

  The cover member 51 is made of, for example, a translucent resin member, and is formed, for example, in a bowl shape by a molding method using a mold. The surface on the front side of the cover member 51 (the surface far from the light source 40) may be formed to have a curved surface for reasons such as improving the appearance of the product. Also, the back surface (surface close to the light source 40) is often flat for reasons such as being in close contact with the LCD element 10.

  With respect to such a liquid crystal display device, the present inventor finds the following technical problems. In other words, the molding of the cover member using the mold needs to produce a mold that is elaborately prepared in advance, so that the overall cost for manufacturing the cover member can be increased.

  The inventor has studied a method of forming the front surface of the cover member into a curved surface without using a mold. This inventor examined the method of making the surface side surface of a cover member into a curved surface by distorting a flat resin member using the hot press method.

  FIG. 2 is a cross-sectional view showing the second liquid crystal display device 102. The LCD element 10 and the light source 40 used in the second liquid crystal display device 102 are the same as those used in the first liquid crystal display device 101 (see FIG. 1). Hereinafter, the LCD element 10 is shown in a simplified manner for convenience.

  The second liquid crystal display device 102 is different in cover member shape from the first liquid crystal display device 101 (see FIG. 1). In the second liquid crystal display device 102, the cover member 52 has a shape in which a plate-like resin member is curved, for example, in a dome shape or an arch shape. The cover member 52 is not particularly limited as long as it is a curved plate-like member, and is formed into a desired shape according to the appearance design of the product.

  The cover member 52 is obtained by bending a flat plate-like resin member having thermoplasticity using, for example, a hot press method. Specifically, a flat acrylic resin or polycarbonate resin is heated and softened, and a concave / convex die, for example, a press die is pressed against the resin member to be bent into a desired shape. By producing a cover member by a method of distorting a flat resin member, it is possible to obtain a cover member having a desired curved surface on the front side without using a closed mold such as an injection mold. it can.

  With respect to such a liquid crystal display device, the present inventor finds the following technical problems.

  The display surface of the LCD element 10 is generally flat. For this reason, no matter how close the LCD element 10 and the cover member 52 are arranged, the cover member 52, which is a curved plate member, and the LCD element 10 having a flat display surface cannot be brought into close contact with each other. Can not. That is, an air layer is interposed in the gap between the LCD element 10 and the cover member 52. The light reflection at the interface between the air layer and the cover member 52 or at the interface with the LCD element 10 can lead to a decrease in display quality such as generation of a ghost image.

  The present inventor has studied a method for improving such deterioration in display quality. The present inventor has studied a method of reducing the light reflection at the interface between the members by providing a light guide member (optical matching member) in the gap between the LCD element 10 and the cover member 52.

  FIG. 3A is a cross-sectional view showing the third liquid crystal display device 103. The LCD element 10, the light source 40, and the cover member 52 used in the third liquid crystal display device 103 are the same as those used in the second liquid crystal display device 102 (see FIG. 2).

  In the third liquid crystal display device 103, a light guide member 60 made of, for example, a gel-like resin member is provided between the cover member 52 and the LCD element 10. The light guide member 60 can be formed by the following method, for example.

  In a vacuum, the cover member 52 and the LCD element 10 are bonded together via a gel-like resin such as silicone. At this time, the gel-like resin member adheres to these members while deforming so as to correspond to the curved shape of the cover member 52 and the flat display surface of the LCD element 10.

  Thereafter, bubbles are removed from the resin member by high-temperature and high-pressure treatment, and the resin member, the cover member 52, and the LCD element 10 are brought into close and uniform contact. Thereby, the light guide member 60 which consists of a gel-like resin member is formed. If a gel-like resin member is used for the light guide member 60, the light guide member 60 can be brought into close contact with the cover member 52 or the LCD element 10 relatively easily regardless of the shape of the cover member 52 or the LCD element 10. it can.

  The refractive indexes of the light guide member 60, the cover member 52, and the LCD element 10 (especially, the glass substrates 21 and 22, constituting the same, see FIG. 1) are substantially equal, for example within the range of 1.4 to 1.6. is there. The refractive index of the light guide member 60 is preferably within a range of ± 0.1 of the refractive index of the cover member 52 or the LCD element 10 (or its glass substrate). Since the refractive indexes of the light guide member 60, the cover member 52, and the LCD element 10 are substantially equal, light reflection at the interface between them is reduced, and deterioration in display quality such as generation of a ghost image is suppressed.

  FIG. 3B is a cross-sectional view showing a modification 103a of the third liquid crystal display device. For the light guide member 60, for example, a fiber plate including a configuration in which a large number of optical fibers having a diameter of several microns are bundled and cut may be used. The fiber plate may be urexite that produces a fiber effect. The fiber plate is sometimes called a fiber optic plate or an image fiber. Moreover, as shown to FIG. 3B, you may make it the structure which embedded the fiber plate 62 in the translucent resin member 61. FIG. When the fiber plate is used, when the pattern displayed by the LCD element is viewed from the cover member side, the pattern is recognized at a position closer to the cover member.

  FIG. 4A is a cross-sectional view showing the fourth liquid crystal display device 104. Basic components are the same as those of the third liquid crystal display device 103 (see FIG. 3A).

  In the fourth liquid crystal display device 104, the LCD element 10 is tilted with respect to a virtual plane orthogonal to the optical axis 41 of the light source 40. According to the study of the present inventor, when the LCD element 10 is disposed at an inclination, the brightness and brightness of the pattern displayed by the LCD element 10 change.

  The inventor measured the observation angle dependency of the light transmittance in the LCD element 10 alone in the following manner. That is, a light source is disposed behind the LCD element 10, and the LCD element 10 is tilted (rotated) about the optical axis of the light source and the axis perpendicular to the liquid crystal molecule alignment direction of the LCD element 10 to display the display surface side. From this, the light transmittance of the LCD element 10 was measured.

  The posture / mode when the LCD element is directly facing the light source (orthogonal to the optical axis of the light source) is taken as a reference (observation angle = 0 °). The direction when the LCD element is tilted is set to a positive rotation (tilt) direction so that the liquid crystal molecule alignment direction faces the light source. Conversely, the direction when the LCD element is tilted is set to a negative rotation (tilt) direction so that the liquid crystal molecule alignment direction is opposite to the light source.

  FIG. 4B is a graph showing the light transmittance of the LCD element alone when the LCD element is tilted when a voltage is applied (translucent state). The horizontal axis indicates the tilt angle (observation angle) of the LCD element, and the vertical axis indicates the light transmittance of the LCD element.

  When the inclination of the LCD element is 0 °, the light transmittance of the LCD element is about 13%. When the LCD element is tilted (rotated) in the positive direction, the light transmittance monotonously increases until the tilt reaches about 40 °. On the other hand, when the LCD element is tilted (rotated) in the negative direction, the light transmittance monotonously decreases until the tilt becomes approximately −30 °.

  It can be seen from the graph shown in FIG. 4B that the light transmittance changes by tilting the LCD element. As shown in FIG. 4A, by tilting the LCD element 10, the brightness and brightness of the pattern displayed by the LCD element 10 can be adjusted. If a gel-like resin member is used for the light guide member 60, the light guide member 60 can be brought into close contact with the cover member 52 or the LCD element 10 relatively easily regardless of the inclination of the LCD element 10.

  FIG. 5 is a plan view showing a segment electrode pattern (segment electrode 24, see FIG. 1) of the LCD element. Assume that the display pattern of the fourth liquid crystal display device 104 (see FIG. 4A) is projected on a screen orthogonal to the optical axis of the light source. When the LCD element is disposed at an angle, the display pattern by the LCD element can be projected in a trapezoidal shape on the screen. In such a case, as shown in FIG. 5, the segment electrode may be formed so that the distortion is corrected in consideration of the distortion of the display pattern at the time of projection. The display pattern distortion may be corrected so as to increase the trapezoidal distortion and the distortion may be emphasized.

  Since the cover member 52 (see FIG. 4), which is a curved plate member, can also function as an optical lens, the display pattern by the LCD element can be distorted on the screen depending on the shape of the cover member. In such a case, the segment electrode may be formed so that the distortion is corrected.

  As mentioned above, although this invention was demonstrated based on some Examples, this invention is not limited to these. For example, the LCD element could be replaced by a display device such as a so-called organic EL (electroluminescence) element. It will be apparent to those skilled in the art that other various modifications, improvements, combinations, and the like are possible.

DESCRIPTION OF SYMBOLS 10 ... Liquid crystal display element, 20 ... Liquid crystal cell, 21, 22 ... Substrate, 23, 24 ... Electrode (segment type), 25, 26 ... Alignment film, 27 ... Liquid crystal layer, 31, 32 ... Polarizing plate, 40 ... Light source, DESCRIPTION OF SYMBOLS 41 ... Optical axis, 51, 52 ... Cover member, 60, 61 ... Light guide member, 62 ... Fiber plate, 101-104 ... Liquid crystal display device.

Claims (5)

A display device for displaying a desired pattern;
A translucent resin member disposed on the display surface side of the display device and having a curved plate shape;
Between the display device and the translucent resin member, a light guide member disposed in close contact with both the display device and the translucent resin member;
A display device. The display device is
A light source;
A liquid crystal cell disposed on the optical axis of the light source;
A pair of polarizing plates arranged to sandwich the liquid crystal cell;
The display device according to claim 1, comprising:   The display device according to claim 2, wherein the liquid crystal cell is of a vertical alignment type and is inclined with respect to a virtual plane orthogonal to the optical axis of the light source.   The display device according to claim 1, wherein a refractive index of the light guide member is in a range of −0.1 to +0.1 of a refractive index of the display device and the translucent resin member. The display device according to claim 1, wherein the light guide member is made of a gel-like resin material.

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