JP2009175709A - Display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that when an anti-reflection film is formed on the display viewing side surface of a transparent substrate in a display device in which the transparent substrate configuring a cover plate or the like is formed on a display panel, a fingerprint, an oil film or the like is liable to adhere thereon and soil due to the fingerprint, the oil film or the like may be noticeable on the surface of the anti-reflection film. <P>SOLUTION: In the display device on which the transparent substrate is installed, the anti-reflection film is formed on the display viewing side surface of the transparent substrate and a silicon oxide film for anti-soiling is formed on the anti-reflection film to prevent the fingerprint, the oil film or the like from being liable to adhere to the surface of the anti-reflection film, and even when adhering thereon, to prevent the fingerprint, the oil film or the like from being noticeable. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a display device in which a translucent substrate is installed on the surface of the display panel on the display viewing side. Specifically, the present invention relates to a display device having a configuration in which a cover plate and a touch panel are provided on the surface of a display panel.

  Flat panels such as liquid crystal panels, organic EL panels, and plasma display panels are used for portable devices such as cellular phones. When a flat panel is used for a portable device, the display panel is stored in a housing, and a front plate is attached to the display surface side to protect the display surface. Moreover, it may replace with a front plate and a touch panel may be provided in the display visual recognition side (for example, refer patent document 1).

  However, when a front plate, a touch panel, or the like is installed on the surface of the display panel, display light emitted from the display panel is attenuated by reflection on the surface of the light-transmitting substrate that constitutes the front plate or touch panel. In addition, external light is reflected on the surface of the light-transmitting substrate, and display visibility is reduced. Furthermore, since display panels used in portable devices are required to have low power consumption, not only low power consumption of the display panel itself but also display light emitted from the display panel can be efficiently emitted without being attenuated as much as possible. There is a need.

Therefore, efforts have been made to reduce the reflection loss of the surface by forming an antireflection film on the surface of the translucent substrate. On the other hand, when the display panel is used in a portable device, there are many opportunities to touch the display surface with a hand or a finger when carrying the display panel. Also, depending on the usage environment, oil films and other dirt are likely to adhere.
Japanese Patent Laid-Open No. 9-274536

  The antireflection film formed on the surface of the translucent substrate reduces the reflection loss on the surface of the substrate by utilizing the interference of light in the antireflection film and improves the transmittance. When dirt adheres to the surface of such a highly transparent light-transmitting substrate, the dirt becomes conspicuous. In addition, when a user's fingerprint, sweat, or oil film adheres to the surface of the antireflection film, the light interference condition of the adhered part changes, highlighting dirt, and reducing the visibility of the display.

  Therefore, the display device of the present invention is a display device having a display panel and a translucent substrate installed on the display surface side of the display panel, and an antireflection film is provided on the surface of the translucent substrate on the display viewing side. An antifouling silicon oxide film was formed on the surface of the antireflection film. Further, a light-transmitting adhesive is filled between the display panel and the light-transmitting substrate and bonded.

  The surface of the silicon oxide film is configured such that the contact angle with water is in the range of 80 ° to 180 °. Further, the silicon oxide film is formed so that the hardness is in a range of 6H to 9H in terms of pencil hardness.

  At this time, a single layer film made of magnesium fluoride was used as the antireflection film. Further, the surface of the translucent substrate on which the silicon oxide film is formed has a light transmittance of 98% to 99%.

  Here, the transparent substrate may be a substrate constituting a front plate, a substrate constituting a touch panel, or the like. A capacitively coupled touch panel may be disposed between the translucent substrate constituting the front plate and the display panel.

  In the display device of the present invention, an antireflection film and a silicon oxide film are sequentially formed on the surface of a translucent substrate exposed to the outside. Therefore, it becomes difficult for dirt to adhere to the surface, and even if it adheres, the dirt becomes inconspicuous and it is possible to prevent the display from becoming difficult to see.

  In the display device of the present invention, a front plate and a touch panel are installed on the display surface side of the display panel. Anti-fouling silicon oxide film to prevent fingerprints and other dirt from being formed on the surface of the light-transmitting substrate, which is a component of the front plate and touch panel, on the viewer's side Is formed. As a result, there is an advantage that fingerprints and oil films are difficult to adhere, and even if fingerprints and dirt are attached, they are not noticeable.

  Examples of the display panel include a flat display panel such as a liquid crystal panel, an organic EL panel, and a plasma display panel. Examples of the translucent substrate used for the front plate and the like include substrates made of plastic materials such as glass, acrylic resin (PMMA: methyl methacrylate resin), and polycarbonate resin. A magnesium fluoride film can be used as the antireflection film. A single layer magnesium fluoride film or a multilayer structure combined with other dielectric materials can be used as an antireflection film. Note that it is advantageous in terms of cost to use single-layer magnesium fluoride.

  As the silicon oxide film, a silicon dioxide oxide film, a silicon monoxide oxide film, or SiOx (1 <x <2) can be used. The silicon oxide film can be formed by a sputtering method using silicon oxide as a target, or a reactive sputtering method in an oxygen atmosphere using silicon oxide or a silicon substrate as a target. Further, a silicon oxide film can be formed by a CVD method using silane gas and oxygen gas or a plasma CVD method.

  In addition, a light-transmitting adhesive can be filled between the display panel and the light-transmitting substrate. As the translucent adhesive, a UV curable adhesive, a visible light curable adhesive, a thermosetting adhesive, or a transparent adhesive sheet is used. By approximating the refractive index of the light-transmitting adhesive with the refractive index of the surface material of the light-transmitting substrate or display panel, the display light emitted from the display panel can be reflected on the surface of the light-transmitting substrate or the surface of the display panel. The reflection loss can be reduced. Moreover, since the translucent substrate and the display panel are integrated by the translucent adhesive, the impact resistance of the display panel is improved.

  Further, the contact angle of the silicon oxide film surface with respect to water is set in the range of 80 ° to 180 °. Thereby, the surface of the translucent substrate is converted to water repellency, and fingerprints, sweat, or an oil film is difficult to adhere. For example, when magnesium fluoride is exposed as an antireflection film, the contact angle with water is 30 ° or less. By forming a silicon oxide film on this surface, it can be converted to a water-repellent surface, and dirt can be made difficult to adhere. Further, the pencil hardness of the surface of the silicon oxide film is set in the range of 6H to 9H. Thereby, since the display surface becomes high hardness, it is hard to be damaged. The contact angle of water on the surface of the silicon oxide film may be in the range of 80 ° to 180 °, and the pencil hardness of the surface may be in the range of 6H to 9H.

  Further, a capacitively coupled touch panel can be disposed between the translucent substrate constituting the front plate and the display panel. Thereby, it becomes possible to input information from the display surface side. In particular, a capacitively coupled touch panel does not have a surface such as an air layer inside the touch panel, and thus can reduce reflection loss of display light when applied to a display device.

  Hereinafter, the present invention will be specifically described based on each example. In this embodiment, a liquid crystal panel is used as the display panel. Basically, the same reference numerals are given to the same parts or parts having the same function.

FIG. 1 is a cross-sectional view schematically showing a front plate of the display device of this embodiment. The antireflection film 2 is formed on the surface of the translucent substrate 1, and the silicon oxide film 3 is formed on the surface thereof. Glass was used as the translucent substrate 1. As the antireflection film 2, a single layer of magnesium fluoride (MgF ₂ ) was formed by sputtering. As the silicon oxide film 3, a silicon dioxide film was deposited by 1050 mm by sputtering. The film thickness of the silicon oxide film 3 is not limited to this. The wavelength can be about ½ or less of the wavelength of visible light, for example, 2,000 to ˜100.

  When the transmittance of the surface on which the silicon oxide film 3 was formed was measured, it was 98.5% in visible light. The transmittance when the antireflection film 2 was deposited before the silicon oxide film 3 was deposited was 96.1%. Therefore, the transmittance is improved by 2.4% by forming the silicon oxide film 3. The surface of the silicon oxide film 3 had a pencil hardness of 6H or higher. Therefore, it was possible to make the surface difficult to be scratched.

  The wettability of the surface of the silicon oxide film 3 was 98 ° for water and 61 ° for oleic acid. The contact angle of the antireflection film 2 made of a magnesium fluoride film before the silicon oxide film 3 was deposited was 24 ° with respect to water and 20 ° with respect to oleic acid. That is, by depositing the silicon oxide film 3, the surface could be converted to a water-repellent surface.

  FIG. 2 schematically shows a cross-sectional configuration of the liquid crystal display device 10 of the present embodiment. As illustrated, the liquid crystal display device 10 includes a translucent substrate 1, a liquid crystal panel 12, and a backlight 15. The liquid crystal panel 12 has a configuration in which a liquid crystal layer 6 is sealed between an upper substrate 4 and a lower substrate 5 made of glass by using a sealing material 7, and an upper polarizing plate 8 is disposed on the outer surface of the upper substrate 4. A lower polarizing plate 9 is affixed to the outer surface. The lower substrate 5 protrudes from the upper substrate 4, a driver IC 13 for driving the liquid crystal layer 6 is mounted on the inner surface side of the protruding portion, and a flexible connector 14 for transmitting a drive signal to the driver IC 13 is connected. Has been.

  The translucent substrate 1 and the liquid crystal panel 12 are bonded by a translucent adhesive 16. As the translucent adhesive 16, a UV curable adhesive or a visible light curable adhesive was used. Compared with a thermosetting adhesive, a UV curable adhesive or a visible light curable adhesive does not need to be heated and has a low curing shrinkage rate. Therefore, the liquid crystal layer 6 is deteriorated due to deterioration or shrinkage of the upper and lower polarizing plates 8 and 9. The stress applied to can be reduced. A translucent adhesive 16 in which a thermosetting adhesive is added to a photocurable adhesive can also be used. Since the liquid crystal panel 12 is fixed to the translucent substrate 1 by the translucent adhesive 16, the impact resistance of the liquid crystal panel 12 is improved.

  Here, the refractive index of the translucent adhesive 16 is set to 1.50 to 1.55, for example. By approximating the refractive index of the translucent adhesive 16 to the translucent substrate 1 and the upper polarizing plate 8, the interface between the lower surface of the translucent substrate 1 and the translucent adhesive 16, and the upper polarizing plate The reflection loss of light at the interface between 8 and the translucent adhesive 16 could be reduced.

  In FIG. 2, the liquid crystal panel 12 may be turned upside down. The liquid crystal panel 12 may be a simple matrix type liquid crystal panel or an active matrix type liquid crystal panel in which a TFT element is formed in each pixel, and the type of liquid crystal is not limited. In addition, a backlight 15 is installed in the lower part, and a diffusion plate or a prism sheet for controlling the direction of light emitted from the backlight 15 is inserted between the backlight 15 and the liquid crystal panel 12. Can do. Further, as the backlight 15, an EL light emitting sheet or a type in which an LED is installed at an end portion and light is guided upward by a light guide plate can be used.

  Further, in FIG. 2, the upper polarizing plate 8 is attached to the upper substrate 4. However, the upper polarizing plate 8 may be attached to the surface of the translucent substrate 1 on the liquid crystal panel 12 side. Good. In addition, a quarter-wave plate for anti-glare can be installed on the surface of the upper polarizing plate 8 or the surface of the translucent substrate 1 on the liquid crystal panel 12 side.

  By configuring the liquid crystal display device 10 as described above, the reflection loss on the display viewing side surface of the translucent substrate 1 is reduced, and an air layer is formed between the liquid crystal panel 12 and the translucent substrate 1. Since the refractive index of the translucent adhesive 16 was approximated to the refractive index of both substrates without interposing, the reflection loss of the display light emitted from the liquid crystal panel 12 could be greatly reduced. In addition, since the exposed surface of the liquid crystal display device 10 is a water-repellent surface, fingerprints and the like are hardly attached. In addition, even when fingerprints or the like were attached, it became inconspicuous. Furthermore, since the pencil hardness of the silicon oxide film 3 is set to 6H or more, the exposed surface can be hardly damaged.

In the present embodiment, the translucent substrate 1 is described as a component of the front plate. However, the translucent substrate constituting the touch panel is basically the same. The configuration of the liquid crystal display device in this case is schematically shown in FIG. In the same manner as described above, the antireflection film 2 and the antifouling silicon oxide film 3 are sequentially formed on the viewer side of the translucent substrate constituting the input element 11 such as a touch panel or a touch switch. The liquid crystal panel is pasted with a translucent adhesive 16.

  FIG. 4 schematically shows a cross-sectional configuration of the liquid crystal display device 10 according to the present embodiment. The difference from the liquid crystal display device 10 of FIG. 2 is that a capacitively coupled touch panel is inserted between the liquid crystal panel 12 and the translucent substrate 1 constituting the front plate. The other configuration is the same as the configuration of FIG.

  The translucent substrate 1 and the touch panel 17 are bonded by a translucent adhesive 16. Similarly, the touch panel 17 and the liquid crystal panel 12 are also bonded by the translucent adhesive 16. The capacitive touch panel 17 has a transparent conductive film formed on the surface of a transparent substrate such as glass. When the user touches the surface opposite to the surface on which the transparent conductive film is formed with a finger or the like, the capacitance between the touched portion and the transparent conductive film changes. The current fluctuation accompanying this capacitance change is detected two-dimensionally, and the position touched by the finger or the like is calculated. Therefore, unlike a resistive film type touch panel, there is no need to interpose an air layer, so that a touch panel that is thin and has low light reflection loss on the surface can be incorporated.

Also in this case, the reflection loss of light on the surface of the touch panel can be reduced by approximating the refractive index of the translucent adhesive 16 and the refractive index of the glass substrate of the touch panel. Further, since the antireflection film 2 and the silicon oxide film 3 as an antifouling film are formed on the surface of the translucent substrate 1, fingerprints are difficult to adhere and display is difficult to see. Can be prevented.

By forming the antireflection film and the silicon oxide film in order on the surface of the transparent substrate exposed to the outside as in the configuration of each embodiment described above, it is difficult for dirt to adhere to the surface. It is possible to prevent the dirt from becoming conspicuous and making the display difficult to see.

It is typical sectional drawing of the translucent board | substrate used for the display apparatus of this invention. It is typical sectional drawing of the display apparatus of this invention. It is typical sectional drawing of the display apparatus of this invention. It is typical sectional drawing of the display apparatus of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Translucent substrate 2 Antireflection film 3 Silicon oxide film 4 Upper substrate 5 Lower substrate 6 Liquid crystal layer 7 Spacer 8 Upper polarizing plate 9 Lower polarizing plate 10 Liquid crystal display device 11 Input element 12 Liquid crystal panel 17 Capacitive touch panel

Claims (8)

In a display device in which a translucent substrate is installed on the display surface side of the display panel,
A display device, wherein an antireflection film is formed on a surface of the translucent substrate on the display viewing side, and an antifouling silicon oxide film is formed on the surface of the antireflection film.   The display device according to claim 1, wherein a light-transmitting adhesive is filled between the display panel and the light-transmitting substrate.   3. The display device according to claim 1, wherein the surface of the silicon oxide film has a contact angle with water in a range of 80 ° to 180 °.   The display device according to claim 1, wherein the silicon oxide film has a pencil hardness in a range of 6H to 9H.   The display device according to claim 1, wherein the antireflection film is a single layer film made of magnesium fluoride.   6. The surface of the translucent substrate on which the silicon oxide film is formed has a light transmittance in a range of 98% to 99%. Display device.   The display device according to claim 1, wherein a capacitive coupling touch panel is sandwiched between the translucent substrate and the display panel.   The display device according to claim 7, wherein the translucent substrate is a substrate constituting a front plate.

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