Indication device

Abstract

The present invention provides a display device that reduces the possibility of transparent adhesive, which may have seeped out from between the liquid crystal display panel and the protective panel during bonding, adhering to the electrode portion of the liquid crystal display panel. [Solution] A display device 100 comprising a liquid crystal display panel 2 and a protective panel 1 covering the front side of the liquid crystal display panel 2, wherein the front side of the liquid crystal display panel 2 and the back side of the protective panel 1 are joined with a transparent adhesive 3, the liquid crystal display panel 2 comprising a front glass 2a facing the back side of the protective panel 1 and a back glass 2b laminated on the back side of the front glass 2a, the back glass 2b having an electrode portion 2c to which wiring is connected, and the thickness t1 of the front glass 2a is thicker than the thickness t2 of the back glass 2b.

Description

Technical Field

[0001] The present disclosure relates to a display device.

Background Art

[0002] There is known a display device including a liquid crystal display panel and a protective panel covering the front side of the liquid crystal display panel, and joining the front side of the liquid crystal display panel and the back side of the protective panel with a transparent adhesive (see, for example, Patent Document 1). In this type of display device, even if there are warps or sink marks on the back side of the protective panel, the liquid crystal display panel and the protective panel can be properly joined by increasing the application amount of the transparent adhesive.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, when the application amount of the transparent adhesive is increased, the amount of the transparent adhesive protruding from between the liquid crystal display panel and the protective panel also increases, and the protruding transparent adhesive may adhere to the electrode portion of the liquid crystal display panel.

[0005] Therefore, an object of the present disclosure is to provide a display device capable of reducing the possibility that the transparent adhesive protruding from between the liquid crystal display panel and the protective panel during joining adheres to the electrode portion of the liquid crystal display panel.

Means for Solving the Problems

[0006] In one aspect, the following solution means is provided. A liquid crystal display panel, a protective panel covering the front side of the liquid crystal display panel, A display device in which the front side of the liquid crystal display panel and the back side of the protective panel are joined together with a transparent adhesive, The aforementioned liquid crystal display panel is The front glass facing the back of the protective panel, The front glass is laminated on the back side, and the glass comprises a back glass laminated on the back side of the front glass, The aforementioned back glass has an electrode portion to which wiring is connected, The thickness of the front glass is greater than the thickness of the back glass. [Effects of the Invention]

[0007] According to this disclosure, the possibility of transparent adhesive that squeezes out from between the liquid crystal display panel and the protective panel during bonding adhering to the electrode portion of the liquid crystal display panel can be reduced. [Brief explanation of the drawing]

[0008] [Figure 1] This is a schematic front view of a display device according to an embodiment of the present disclosure. [Figure 2] This is a schematic cross-sectional view of AA in Figure 1. [Figure 3] Figure 1 is an enlarged cross-sectional view of the main part of the BB. [Figure 4] (a) is a cross-sectional view showing a protective panel of a display device according to the first modified example of the present disclosure, and (b) is a cross-sectional view showing a protective panel of a display device according to the second modified example of the present disclosure. [Modes for carrying out the invention]

[0009] The following describes the embodiments in detail with reference to the attached drawings.

[0010] The display device 100 according to the embodiment of this disclosure will be described with reference to Figures 1 to 3. The display device 100 is mounted on a vehicle (automobile, motorcycle, agricultural machinery, construction machinery, etc.) and is configured as an instrument that displays information such as vehicle speed. In Figure 2, the printed layer 1e is not shown.

[0011] In the following, to facilitate understanding of the configuration of the display device 100, for each component, the direction in which the display device 100 views the user seated in the vehicle driver's seat will be referred to as "front" or "front," and the opposite side as "back" or "rear."

[0012] The display device 100 comprises a protective panel 1, a liquid crystal display panel 2, a transparent adhesive 3, a circuit board 4, and a case member 5.

[0013] The protective panel 1 covers the front side of the liquid crystal display panel 2. The protective panel 1 is made of a translucent (including transparent and translucent) plate member 1a as the base material and has a translucent region 1b and a light-blocking region 1c. The plate member 1a that serves as the base material is made of resin such as PMMA, POM, PPS, PET, or PC. The resin plate member 1a may have areas with partially different thicknesses (hereinafter sometimes referred to as unevenness) due to warping or sink marks. For example, as shown in Figure 4(a), the curved protective panel 1B with a convex shape on the front side is prone to unevenness due to the effect of warping. Also, as shown in Figure 4(b), the protective panel 1C in which the thickness on the central side is thicker than the thickness on the outer edge side is prone to unevenness on the central side due to the effect of sink marks. Note that in Figure 4, the cross-sectional shapes of protective panels 1B and 1C are exaggerated for ease of understanding.

[0014] The light-shielding region 1c is formed by a light-shielding printed layer 1e applied to the back surface 1d of the outer periphery of the protective panel 1. The color of the printed layer 1e is the same as or similar to the color of the case member 5. For example, if the color of the case member 5 is black, the printed layer 1e is formed using black ink.

[0015] The light-transmitting region 1b is formed inside the light-shielding region 1c. The light-transmitting region 1b is a region where the printed layer 1e is not formed and the light-transmitting properties of the plate member 1a are maintained, and it has, for example, a horizontally elongated rectangle shape.

[0016] The back surface 1d of the outer periphery of the protective panel 1 is joined to the case member 5 by laser welding. Laser welding will be described later.

[0017] The liquid crystal display panel 2 is composed of a TFT liquid crystal (Thin-Film Transistor Liquid Crystal Display) or the like, and displays various vehicle information and the like. The display state (display content) of the liquid crystal display panel 2 is controlled by a vehicle control unit (not shown). The various vehicle information displayed by the liquid crystal display panel 2 is, for example, vehicle speed, engine speed, accumulated driving distance, remaining driving distance, average fuel consumption, the situation of other surrounding vehicles, etc.

[0018] The display area of the liquid crystal display panel 2 has a horizontally long rectangle whose outer shape as seen from the user is the same size as the light-transmitting area 1b, and is arranged on the back side of the protective panel 1 so as to face the light-transmitting area 1b. Thereby, the display area of the liquid crystal display panel 2 is visually recognized by the driver through the light-transmitting area 1b of the protective panel 1. Also, the area outside the display area of the liquid crystal display panel 2 is shielded by the light-shielding area 1c of the protective panel 1.

[0019] The liquid crystal display panel 2 includes a front glass 2a facing the back side of the protective panel 1 and a back glass 2b laminated on the back side of the front glass 2a. An electrode portion 2c for connecting a liquid crystal wiring (not shown) is provided on the back glass 2b. For example, the back glass 2b has an extending portion 2d extending outward from the front glass 2a, and the electrode portion 2c is provided on the front side of the extending portion 2d.

[0020] The thickness t1 of the front glass 2a is made thicker than the thickness t2 of the back glass 2b. For example, the thickness t1 of the front glass 2a is 1.1 mm and the thickness t2 of the back glass 2b is 0.7 mm. The reason for this will be described later.

[0021] The transparent adhesive 3 is a highly transparent adhesive that joins the front side of the liquid crystal display panel 2 and the back side of the protective panel 1. As the transparent adhesive 3, an optically transparent resin such as a silicone-based, acrylic-based, or urethane-based resin, which is also called OCR (Optical Clear Resin), can be applied. Also, the transparent adhesive 3 may be an ultraviolet curable type or other heat curable type or the like.

[0022] When joining the liquid crystal display panel 2 and the protective panel 1 using transparent adhesive 3, the protective panel 1 is held with its back side facing upwards, and then the transparent adhesive 3 is applied to the back surface of the protective panel 1. The area where the transparent adhesive 3 is applied should be approximately the same as, or wider than, the surface area of ​​the front glass 2a of the liquid crystal display panel 2. Next, the surface of the liquid crystal display panel 2 (front glass 2a) is placed on top of the applied transparent adhesive 3, and the surface of the liquid crystal display panel 2 is bonded to the back surface of the protective panel 1 via the transparent adhesive 3. At this time, the transparent adhesive 3 is subjected to the weight of the liquid crystal display panel 2 or a moderate downward force. As a result, the transparent adhesive 3 not only adheres to the entire surface of the front glass 2a while filling in the irregularities on the back surface of the protective panel 1, but also extends beyond the gap between the protective panel 1 and the front glass 2a and adheres to the edge (side) of the front glass 2a. After that, the transparent adhesive 3 hardens and joins the protective panel 1 and the liquid crystal display panel 2. The thickness of the transparent adhesive 3 after curing is, for example, 0.7 to 1.0 mm.

[0023] According to the bonding method described above, even if there are irregularities on the back surface of the protective panel 1, it is possible to firmly bond the back surface of the protective panel 1 to the front glass 2a of the liquid crystal display panel 2. However, with this bonding method, the amount of transparent adhesive 3 that squeezes out from between the protective panel 1 and the front glass 2a varies depending on the size of the irregularities on the back surface of the protective panel 1. As a result, the squeezed transparent adhesive 3 may adhere not only to the edge of the front glass 2a but also to the electrode portion 2c of the back glass 2b.

[0024] Therefore, in the liquid crystal display panel 2, as mentioned above, the thickness t1 of the front glass 2a is made thicker than the thickness t2 of the back glass 2b. This reduces the possibility that the transparent adhesive 3 that has seeped out from between the protective panel 1 and the front glass 2a will reach the back glass 2b or the electrode portion 2c, and even if it does reach them, the amount of transparent adhesive 3 adhering to the electrode portion 2c can be reduced.

[0025] The circuit board 4 is positioned on the back side of the liquid crystal display panel 2. The circuit board 4 is, for example, a rigid wiring board with a wiring pattern (not shown) applied to a flat substrate, and is electrically connected to the liquid crystal display panel 2 via the aforementioned liquid crystal wiring. Various circuit components (not shown) are mounted on the circuit board 4, and these circuit components and the wiring pattern constitute the drive circuit for the liquid crystal display panel 2.

[0026] The case member 5 supports the protective panel 1 so as to surround the liquid crystal display panel 2 on the back side of the protective panel 1, and houses the liquid crystal display panel 2 and the circuit board 4. The case member 5 is made of a synthetic resin (e.g., AES, ABS) that has light-absorbing and thermoplastic properties. The color of the case member 5 is the same as or similar to the color of the printed layer 1e. In this embodiment, the case member 5 and the printed layer 1e are black.

[0027] The case member 5 has a box shape consisting of a bottom portion 5a and side wall portions 5b, with an opening 5c ​​formed on the front side. A protective panel 1 is attached to the front side of the case member 5 so as to close the opening 5c.

[0028] The bottom portion 5a is located on the back side of the circuit board 4. The side wall portion 5b rises from the outer periphery of the bottom portion 5a and is formed to surround the liquid crystal display panel 2 on the back side of the protective panel 1. The front end of the side wall portion 5b has a bonding surface 5d that is joined to the back side portion 1d on the outer periphery of the protective panel 1 by laser welding.

[0029] Next, the laser welding process mentioned above will be explained with reference to Figure 3.

[0030] The back surface 1d on the outer periphery of the protective panel 1 and the joining surface 5d of the case member 5 are joined by laser welding. Laser light is shone from the front side of the protective panel 1 toward the joining surface 5d of the case member 5. The joining surface 5d of the case member 5 absorbs the laser light and generates heat, and this heat melts and bonds the joining region S of the case member 5 and the protective panel 1. When solidified, a welded portion Y is formed. As a result, the back surface 1d on the outer periphery of the protective panel 1 and the joining surface 5d of the case member 5 are joined via the welded portion Y.

[0031] The laser beams used for laser welding include YAG lasers, diode lasers, fiber lasers, and infrared lasers. The laser beam moves along the longitudinal direction of the bonding region S (the direction of the outer periphery of the protective panel 1) and is irradiated onto the bonding region S with a predetermined laser irradiation diameter R.

[0032] The back surface 1d on the outer periphery of the protective panel 1 has a non-printed area 1f where the printed layer 1e is not formed, corresponding to the joint area S formed by laser welding. Not only is the light-shielding printed layer 1e absent in the non-printed area 1f, but also the transparent and semi-transparent printed layers.

[0033] The unprinted area 1f has a strip shape with a predetermined width W sandwiched between the printed layers 1e. Furthermore, the predetermined width W is set to be narrower than the laser irradiation diameter R for laser welding. With this configuration, when laser light is irradiated from the front side to the back side of the protective panel 1 during the laser welding described above, the laser light that has passed through the unprinted area 1f is irradiated onto the joint surface 5d of the case member 5. The joint surface 5d of the case member 5 absorbs the laser light and generates heat, and this heat melts and bonds the joint area S of the case member 5 and the protective panel 1. At this time, since the printed layer 1e is not interposed between the case member 5 and the protective panel 1 in the joint area S, the melt bonding between the case member 5 and the protective panel 1 is not hindered by the printed layer 1e, and the bonding strength of the welded part Y can be increased.

[0034] Furthermore, since the width W of the unprinted area 1f is set to be narrower than the laser irradiation diameter R, during laser welding, the entire unprinted area 1f of the protective panel 1 is melted and bonded with the case member 5, forming a band-shaped welded area Y that exhibits a nearly uniform black color. Since the welded area Y is formed without gaps between the adjacent black printed layers 1e on both sides, the welded area Y and the printed layers 1e appear as one, making the welded area Y difficult to see.

[0035] Furthermore, the outer surface portion 1g of the protective panel 1 has a tapered surface 1h in the region facing the welded portion Y, which is inclined to recede further outward from the surface portion 1g of the light-transmitting region 1b. In this way, the tapered surface 1h promotes external light reflection from the perspective of a user viewing the display device 100 (liquid crystal display panel 2), making it even more difficult to see the state of the welded portion Y.

[0036] Although each embodiment has been described in detail above, the invention is not limited to any particular embodiment, and various modifications and changes are possible within the scope described in the claims. Furthermore, it is possible to combine all or more of the components of the embodiments described above. [Explanation of Symbols]

[0037] 100 display device 1, 1B, 1C protective panel 1a Plate member 1b Translucent area 1c Shading area 1d Back part 1e printing layer 1f No printing area 1g surface area 1h Tapered surface 2. LCD display panel 2a Front glass 2b Back glass 2c Electrode section 2d extension 3. Transparent adhesive 4 Circuit boards 5 Case components 5a Bottom part 5b Side wall part 5c opening 5d joint surface Y welded part S junction area R Laser irradiation diameter W width of the area without printing t1 Thickness of the front glass t2 Back glass thickness

Claims

1. LCD display panel, The system includes a protective panel that covers the front side of the liquid crystal display panel, A display device in which the front side of the liquid crystal display panel and the back side of the protective panel are joined together with a transparent adhesive, The aforementioned liquid crystal display panel is The front glass facing the back of the protective panel, The front glass is laminated on the back side, and the glass comprises a back glass laminated on the back side of the front glass, The aforementioned back glass has an electrode portion to which wiring is connected, A display device in which the thickness of the front glass is greater than the thickness of the back glass.

2. The aforementioned back glass has an extended portion that extends outward from the front glass, The display device according to claim 1, wherein the electrode portion is provided on the extended portion.

3. The display device according to claim 1, wherein the protective panel has a convex shape on its front side.

4. The display device according to claim 1, wherein the thickness of the protective panel is greater on the central side than on the outer end side.

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