JP2008197231A - Image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device that can maintain an image of high picture quality by reducing warpage of a surface film by reducing an influence of heat and preventing the image from having color unevenness and noise even when the image display device is used for a long period of time. <P>SOLUTION: The image display device (color liquid crystal display) 100 has a display panel (liquid crystal display panel) 1 having pixels each composed of a plurality of sub-pixels, and the surface film 3 which is disposed on a top surface of the display panel 1 and diffuses light in each unit pixel, and the rate of thermal expansion length variations of the top surface part and reverse surface part of the surface film 3 is so adjusted that the difference in thermal expansion variation due to the temperature difference between the top surface part and reverse surface part of the surface film 3 becomes substantially 0. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image display device, and more particularly to an image display device provided with a surface film that reduces the influence of thermal expansion.

  In recent years, the demand for color liquid crystal displays instead of CRT displays has been increasing. As an example of this color liquid crystal display, a TFT side substrate module including a switching element such as a TFT is provided in front of a backlight, the counter electrode including the substrate module and a color filter and serving as a counter electrode of the substrate module The structure which provides a liquid-crystal layer between side substrate modules is mentioned. In this liquid crystal display, a light transmitting state and a light blocking state are created for each pixel by the operation of the switching element, and light converted from electric energy passes through the color filter so that a color image is visually recognized in front. .

In the color filter, one colored layer of blue (B), green (G), and red (R), which are the three primary colors, is arranged in each pixel, and light irradiation to each colored layer is performed. It is possible to develop various colors by adjusting the color and mixing these colors. In addition, a black layer has been provided at the boundary between these colored layers in order to improve the visibility such as increasing the display contrast and coloring effect.
Conventionally, in such a color liquid crystal display, when monochrome display is performed, when the screen is viewed at a close distance, color mixture of light constituting adjacent pixels, color separation within the same pixel, or black layer It caused image noise, such as making it stand out.

On the other hand, in Patent Document 1, for each pixel that forms a liquid crystal display screen, a filter panel formed so as to converge each light bundle from three primary color light emitting portions that form each pixel, for example, each pixel A technique is disclosed in which a meniscus concave lens having both sides formed in a concave lens shape is provided on the front surface of the display surface.
Further, in Patent Document 2, among the three color LEDs forming one pixel, the pellets of the two color LEDs are provided outside the optical axis of the resin lens, and the chief rays emitted from the LEDs of the respective colors are cylindrical concave lenses. After refracting and making it parallel, it is configured to diffuse on the display surface, or the principal rays emitted in parallel from the three color LEDs forming one pixel are converged by a convex lens and then made parallel by a diffusion lens. And a technique for diffusing on the display surface is disclosed.
JP-A-5-11243 JP-A-8-202292

However, no matter which technique is used, the three color light beams emitted from the primary color light emitting section or LED are converged from the actual pitch of each light source and projected onto the display surface. When viewed, the gap between the pixels becomes large, and the pixel grid is conspicuous on the contrary.
Therefore, in order to solve such a problem, the present inventors can arrange microlenses corresponding to the subpixels in one pixel that are arranged on the surface of the color display, although they are not yet known. When various color mixing methods using surface film are examined, and a surface film that can optically mix RBG pixels is installed, preventing color separation between adjacent pixels and preventing color separation within the same pixel when viewing the pixels I found a technology to improve the image quality.

However, in the above-described technology, one surface of the surface film is likely to be overheated due to the influence of the generated heat, so that the surface film is warped. As the display time passes, the subpixels of the color display and the optical lens of the surface film As a result, there was a problem that a slight misalignment occurred between the images, and as a result, when the image was displayed for a long time, the effect of color mixing was changed to cause uneven color and noise in the image.

  The present invention has been made in view of the above points, and reduces the influence of heat to reduce the warpage of the surface film, and prevents the occurrence of uneven color and noise even when used for a long time. It is an object of the present invention to provide an image display device capable of maintaining an image with high image quality.

In order to achieve the object, an image display device according to claim 1,
A display panel in which one pixel is formed by a plurality of subpixels;
A surface film disposed on the surface of the display panel for diffusing light in each unit pixel;
In an image display device comprising:
The rate of change in thermal expansion length between the front and back surfaces of the surface film is adjusted so that the difference in rate of change in thermal expansion due to the temperature difference between the front and back surfaces of the surface film is substantially zero. It is characterized by being.

According to a second aspect of the present invention, in the image display device according to the first aspect,
The surface film is composed of three layers: a base material, an incident side film layer positioned on the light incident side surface of the base material, and an output side film layer positioned on the light output side surface of the base material. And
The incident side film layer and the output side film layer are the same material,
The incident side film layer is thinner than the emission side film layer.

According to a third aspect of the present invention, in the image display device according to the first or second aspect,
The thermal expansion length change rate of the surface film is the same as the thermal expansion length change rate of the display panel.

According to a fourth aspect of the present invention, in the image display device according to any one of the first to third aspects,
The display panel is a liquid crystal display panel.

The invention according to claim 5 is the image display device according to any one of claims 1 to 4,
The rate of change in thermal expansion length of the surface film is adjusted by the material or thickness of the surface film.

The invention according to claim 6 is the image display device according to any one of claims 1 to 5,
The display panel further includes a backlight for emitting light.

  According to invention of Claim 1 and Claim 4, 5, and 6, When the surface film arrange | positioned on the surface of a display panel (for example, liquid crystal display panel) deform | transforms with the heat | fever which generate | occur | produces for a long time use. In addition, since the difference between the thermal expansion length change rate of the front surface portion of the surface film and the thermal expansion length change rate of the back surface portion of the front film is substantially 0, the occurrence of warpage of the front film is prevented, Even when used for a long time, it is possible to maintain a high image quality that does not cause uneven color or noise in the image.

  According to invention of Claim 2, when the surface film arrange | positioned on the display panel surface deform | transforms with the heat | fever which generate | occur | produces for a long time use, the incident side film layer of a surface film, and an output side film layer heat Since the difference in expansion length change rate is substantially zero, it is possible to prevent warpage of the surface film and maintain high image quality that does not cause uneven color or noise even when used for a long time. .

  According to invention of Claim 3, when the surface film arrange | positioned on the display panel surface and the display panel surface deform | transforms with the heat | fever which generate | occur | produces for a long time use, a thermal expansion with a display panel and a surface film is carried out. Since the length change rate is the same, it is possible to prevent the display panel and the surface film from being misaligned, and to maintain high image quality that does not cause color unevenness or noise even when used for a long time. .

  Hereinafter, an embodiment of an image display apparatus according to the present invention will be described with reference to FIG. However, the scope of the invention is not limited to the illustrated examples.

FIG. 1 shows a main configuration of a color liquid crystal display 100 which is an example of an image display apparatus as an embodiment according to the present invention.
As shown in FIG. 1, a color liquid crystal display 100 according to this embodiment includes a liquid crystal display panel 1, a backlight 2 that emits light toward the liquid crystal display panel 1, and a surface film 3 that diffuses light that has passed through the liquid crystal display panel 1. , Etc. are provided.

  The liquid crystal display panel 1 is a first panel in which a polarizing plate, a glass substrate, a transparent electrode, an alignment film, a liquid crystal layer, an alignment film, and a transparent electrode (all not shown) are sequentially formed in layers from the backlight 2 side. A layer 11 is provided. A color filter 12 is provided on the surface of the first panel layer 11 on the side where the transparent electrode is exposed and formed.

  The color filter 12 includes blue (B), green (G), and red (R) sub-pixels 12b, 12b, and 12b arranged in this order via a support member 12a, and these three-color sub-pixels 12b. One unit pixel is configured with a pair. A grid-like black boundary line (not shown) is formed on the support member 12a so as to surround each unit pixel.

  The surface of the color filter 12 opposite to the first panel layer 11 side is provided with a second panel layer 13 in which a glass substrate and a polarizing plate (both not shown) are formed in order.

  Thus, the liquid crystal display panel 1 is configured by laminating the first panel layer 11, the color filter 12, and the second panel layer 13 in this order, and the glass substrate of the first panel layer 11 and the second panel layer 13. The color filter 12 is sandwiched between the glass substrate.

  A backlight 2 that emits light toward the liquid crystal display panel 1 is disposed on the side of the liquid crystal display panel 1 that faces the first panel layer 11. As will be described later, the backlight 2 is configured to be able to emit light so that light transmitted through the liquid crystal display panel 1 becomes substantially parallel light. This is because when the image is displayed, the light emitted from the backlight 2 passes through the color filter 12 and then forms an image through the liquid crystal display panel 1. This is to prevent light transmitted through a region corresponding to a specific pixel from spreading on the incident surface side of the surface film 3, which will be described later, beyond the pixel pitch and mixing with light constituting adjacent pixels. This is to prevent light leakage into adjacent pixels in the incident stage.

As a specific configuration of such a backlight 2, a vector radiation coupling type backlight configuration using a circular prism sheet 2a can be applied.
The circular prism sheet 2a is a sheet in which prisms are concentrically arranged, and this sheet is arranged on the upper surface of the light guide plate 2b so that the prism surface is the lower surface, and the reflection sheet 2c is disposed on the lower surface of the light guide plate 2b. Deploy. A concave-convex pattern is formed on the lower surface of the light guide plate 2b. An LED is arranged at the center of the prism at the end of the light guide plate 2b, and light is emitted from the LED. The light incident from the end face of the light plate 2b is totally reflected on the upper and lower surfaces of the light guide plate 2b, and is guided radially and linearly around the LED, and the angle of the incident light is changed by the uneven pattern. When the incident angle to the light guide plate 2b is smaller than the critical angle, light is emitted obliquely from the upper surface of the light guide plate 2b, and the emitted light is refracted by the lower surface prism and directed in a certain direction. Accordingly, substantially parallel light is emitted. As a result, the backlight 2 functions as a backlight capable of emitting substantially parallel light and enables an analytical optical design, and the optimal directivity profile of the emitted light, such as the uniformity and the emission efficiency of the emitted light. Therefore, parallel light with a narrow directivity of emitted light can be emitted.

Here, when the substantially parallel property of the backlight 2 is defined, the condition of the substantially parallel property of the emitted light from the backlight 2 is that the emitted light having a divergence angle of α <θ, where α is the half-value angle of the emitted light. Is substantially parallel light.
Here, θ satisfies tan θ = R / H.
(H: In the sub-pixel 12b closest to the end of one pixel, this is the distance from the position closest to the end of this one pixel to the position reaching the concave surface 8 by making a perpendicular to the surface film 3. 1 is the distance from the end of one pixel to the nearest subpixel 12b.)

  On the surface of the second panel layer 13 of the liquid crystal display panel 1 (the upper surface of the second panel layer 13 in FIG. 1), a sheet-like surface film 3 is disposed. The surface film 3 includes a substrate 5 having a thermal expansion coefficient similar to that of glass, and an incident side film layer 4 and an emission side film layer 6 having substantially the same physical property values are attached to both surfaces of the substrate 5. It has a multilayer structure. Hereinafter, the configuration of the surface film 3 will be described in detail.

An incident-side film layer 4 is provided on the surface of the substrate 5 of the surface film 3 on the liquid crystal display panel 1 side, that is, on the light incident-side surface. The incident side film layer 4 is made of, for example, PET, acrylic resin, or the like.
A diffusion lens 7 is provided on a surface (back surface portion) on the side facing the liquid crystal display panel 1 of the four incident side films, and the diffusion lens 7 has a concave surface that is recessed toward the liquid crystal display panel 1. A portion 8 is formed for each subpixel 12b.

  The concave surface portion 8 is configured to refract the incident light and change its optical path, and the light transmitted through the liquid crystal display panel 1 and incident on the surface film 3 is a concave surface corresponding to each subpixel 12b. The optical path of the surface film 3 is changed by the portion 8 so that the light is diffused into each pixel range on the emission side surface of the surface film 3 (the upper surface of the surface film 3 in FIG. 1).

Specifically, the concave surface portion 8 includes two types of concave surface portions 8 (hereinafter referred to as “first concave surface portion 8a” and “second concave surface portion 8b”, respectively) having different shapes, and one unit pixel. For the three sub-pixels 12b constituting the first concave surface portion 8a, one first concave surface portion 8a corresponds to the second concave surface portion 8b arranged on both sides of the first concave surface portion 8a.
That is, for example, as shown in FIG. 1, when the three subpixels 12b constituting one unit pixel are arranged in the order of B, G, and R, for the G subpixel 12b located at the center, The first concave surface portion 8a corresponds, and a part of the second concave surface portion 8b corresponds to the B subpixel 12b and the R subpixel 12b located on the left and right. The second concave surface portion 8b is configured such that the center of the second concave surface portion 8b is positioned at the boundary with the adjacent pixel of the liquid crystal display panel 1, and one second concave surface portion 8b includes a plurality of adjacent pixels. It corresponds to a subpixel 12b (for example, in FIG. 1, a B subpixel 12b constituting a unit pixel and an R subpixel 12b constituting a unit pixel adjacent to the unit pixel).
The concave surface portion 8 is formed so as to be symmetric with respect to the first concave surface portion 8a corresponding to the subpixel 12b (for example, the G subpixel 12b in FIG. 1) located at the center of one unit pixel. With this configuration, the light emitted from each first concave surface portion 8a and second concave surface portion 8b is diffused within each pixel range and is not emitted to adjacent pixels.

  In addition, an exit-side film layer 6 is provided on the surface of the substrate 5 opposite to the surface on which the entrance-side film layer 4 is formed. The emission side film layer 6 functions as a light diffusion layer, and is configured to diffuse the light transmitted through the surface film 3 within the pixel range. And it is visually observed from the surface (surface part) side on the opposite side to the board | substrate 5 of the output side film layer 6. FIG. The emission-side film layer 6 can be applied with a conventionally known surface sheet for preventing image flickering and color separation, but may be composed of, for example, PET, acrylic resin, or the like.

  Moreover, in this embodiment, the incident side film layer 4 and the output side film layer 6 are set so that the difference in the rate of change in the thermal expansion length between these layers is substantially zero during use. By doing in this way, the curvature of the surface film 3 produced at the time of use is reduced.

  Moreover, in this embodiment, it is preferable that the thermal expansion length change rate at the time of use of the surface film 3 is the same as the thermal expansion length change rate at the time of use of the liquid crystal display panel 1. By doing so, the liquid crystal display panel 1 and the surface film 3 always maintain the same shape when used for a long time.

  In the present embodiment, the color liquid crystal display 100 is viewed from the surface film 3 side toward the backlight 2 side.

  Next, a method of calculating the thermal expansion length change rate (δL / L) due to thermal deformation of the liquid crystal display panel 1 and the surface film 3 will be described.

First, the coefficient of thermal expansion α1 of the liquid crystal display panel 1 can be obtained by the following general formula (1).
_{α1 = {α x + α Z} + (α y -α x -α Z)} t y · E y / (t x · E x + t y · E y + t Z · E z) ··· (1)
In the above equation, α _x , α _y , and α _Z are the thermal expansion coefficients of the first panel layer 11, the color filter 12, and the second panel layer 13, respectively, and t _x , t _y , and t _Z are the first _values , respectively. The thickness (mm) of the panel layer 11, the color filter 12, and the second panel layer 13, E _x , E _y , and E _Z are the Young's modulus (GPa) of the first panel layer 11, the color filter 12, and the second panel layer 13. It is.

Moreover, generally the synthetic _{| combination} thermal expansion coefficient (alpha) _xy of the film which consists of two layers can be calculated _| required by following General formula (2).
α _xy = (α _x · t _x · E _x + α _y · t _y · E _y ) / (t _x · E _x + _ty · E _y ) (2)
In the above equation, α _x and α _y are the thermal expansion coefficients of each layer, t _x and _ty are the thickness (mm) of each layer, and E _x and E _y are the Young's modulus (GPa) of each layer.

Then, the above general formula (2), the synthetic thermal expansion coefficient α2 of the incident-side film layer 4 and the substrate _5, and calculates the synthetic thermal expansion coefficient α3 of the exit-side film layer 6 and the substrate 5.

Next, the thermal expansion change amount δL (mm) indicating the change amount of the length depending on the temperature of each film can be obtained using the following general formula (3).
δL = α × L × δT (3)
In the above equation, α is a coefficient of thermal expansion, L (mm) is the diagonal length of the liquid crystal display panel 1, the incident side film layer 4, and the exit side film layer 6 before use, and δT is a temperature change (° C. ).
At this time, L (mm) is the same value in the liquid crystal display panel 1, the incident side film layer 4, and the emission side film layer 6.
Furthermore, by dividing the thermal expansion change amount δL obtained using the general formula (3) by the diagonal length L, the thermal expansion length change rate δL / L can be obtained.
As described above, the thermal expansion length change amount in the present invention represents the δL, and the thermal expansion length change rate represents δL / L.

  The thermal expansion length change amount δL1 of the liquid crystal display panel 1 is calculated by applying the thermal expansion coefficient α1 of the liquid crystal display panel 1 to the general formula (3).

Further _{, the} change amount δL2 of the thermal expansion length of the incident side film layer 4 based on the synthetic thermal expansion coefficient α2 and the change amount δL3 of the thermal expansion length of the exit side film layer 6 based on the synthetic thermal expansion coefficient α3 are obtained. Are calculated to be the same value.
For this reason, the thermal expansion length change rate δL2 / L of the incident-side film layer 4 and the thermal expansion length change rate δL3 / L of the exit-side film layer 6 based on the thermal expansion length change amounts δL2 and δL3. The difference is calculated to be substantially zero.

Specifically, assuming that the liquid crystal display panel 1 side is 30 ° C. and the outside air on the output side film layer 6 side is 25 ° C., for example, the incident side film layer 4 is 29 ° C. and the output side film layer is inside the surface film 3. 6 has a temperature difference of 26 ° C. At this time, the temperature change of the incident side film layer 4 is δT2 = (29−25) = 4 ° C., and the temperature change of the output side film layer 6 is δT3 = (26−25) = 1 ° C.
In the above case, the temperature change δT2 of the incident side film layer 4 is four times the temperature change δT3 of the output side film layer 6. For this reason, the thickness t1 of the incident side film layer 4 and the thickness t2 of the incident side film layer 4 are set to satisfy t1 × 4 = t2 so as to satisfy δL2 = δL3. That is, by setting the thicknesses of the incident-side film layer 4 and the outgoing-side film layer 6, the combined thermal expansion coefficients α2 and α3 are controlled, and the thermal expansion length change amounts δL2 and δL3 of the respective films are set to appropriate values. Can be adjusted. Therefore, the difference between the thermal expansion length change rate δL2 / L and δL3 / L is substantially zero.

  In the present embodiment, the thermal expansion length variation δL2, δL3 of each film is adjusted to a desired value by adjusting the thicknesses of the incident side film layer 4 and the outgoing side film layer 6, but the incident side The synthetic thermal expansion coefficients α2 and α3 can be controlled by the materials of the film layer 4 and the exit side film layer 6 so that the thermal expansion length change amounts δL2 and δL3 of the respective films can be adjusted to desired values.

Further, at this time, δL1, δL2, and δL3 are all made the same.
That is, the change in the length of the surface film 3 has the same value as the change in the length of the liquid crystal display panel 1.
By doing so, when the liquid crystal display panel 1 is deformed by the influence of heat, the surface film 3 is also deformed by substantially the same length. Accordingly, the subpixels 12b and the concave surface portion 8 of the incident side film layer 4 are prevented from being displaced.

Next, the operation of the color liquid crystal display 100 will be described.
When a signal indicating that an image is displayed on the color liquid crystal display 100 is output, for example, from an external device, the LED is turned on, and light and heat are emitted from the backlight 2.
The light emitted from the backlight 2 passes through the first panel layer 11 in the liquid crystal display panel 1, then passes through the color filter 12, and has a color corresponding to each subpixel 12 b in the color filter 12. And is incident on the second panel layer 13.
Then, the light incident on the second panel layer 13 is substantially parallel light for each subpixel 12b, and is transmitted through the second panel layer 13 while maintaining this state. Next, the light emitted from the second panel layer 13 is incident on the surface film 3 through the concave portion 8, refracted according to the shape thereof, and travels inside the surface film 3 toward the emission side film layer 6. To do.

Here, the light emitted from the concave surface portion 8 corresponding to the sub-pixel 12b constituting one pixel exceeds the range of the light emitted from the concave surface portion 8 located at both ends thereof, and is in the range of light emitted by the adjacent pixels. The light emitted from each concave surface portion 8 is diffused so as to be within the range of light emitted from the same pixel.
Thereafter, in the exit-side film layer 6, the light incident on the exit-side film layer 6 is further diffused, and a color image is displayed in a state where the light transmitted through the subpixels 12b constituting the same pixel is uniformly mixed. .

Further, most of the heat released from the backlight 2 reaches the liquid crystal display panel 1 by heat conduction of the air layer surrounding the backlight 2. The liquid crystal display panel 1 gradually becomes hot as the temperature of the backlight 2 rises, causing thermal deformation.
Similarly, the heat reaching the liquid crystal display panel 1 is successively conducted from the incident side film layer 4 of the surface film 3 facing the liquid crystal display panel 1 to the outgoing side film layer 6 in contact with the outside air. At this time, the temperatures of the incident-side film layer 4, the emitting-side film layer 6 and the substrate 5 constituting the surface film 3 also gradually increase as the temperature of the backlight 2 increases, causing thermal deformation.

  At this time, the thermal expansion length change amount δL1 of the liquid crystal display panel 1, the incident side film layer 4 of the surface film 3, and the thermal expansion length change amounts δL2 and δL3 of the output side film layer 6 have the same value. Yes. With such a value, when the liquid crystal display panel 1 is thermally deformed, the surface film 3 is also deformed by substantially the same length, so that each subpixel 12b and the concave surface portion 8 of the incident-side film layer 4 are displaced. Without being generated, a color image is displayed in a state where light transmitted through the sub-pixels 12b constituting the same pixel is uniformly mixed without being mixed.

  Further, at this time, the thickness t1 of the incident-side film layer 4 is configured to be less than the thickness t2 of the emission-side film layer 6, so that when heat is radiated from the backlight 2, the surface film 3 The effect of the warpage that occurs is mitigated.

That is, since the incident-side film layer 4 and the emission-side film layer 6 have substantially the same physical property values, the thermal expansion length change amounts δL2 and δL3 due to thermal deformation thereof depend on the temperature change δT (° C.). Differences. Since the incident side film layer 4 is closer to the liquid crystal display panel 1 than the output side film layer 6, the temperature change δT (° C.) is large. For this reason, the coefficient of thermal expansion is large and warping is likely to occur. .
However, when δL2 = δL3 and t2> t1 is satisfied, the incident-side film layer 4 and the emission-side film layer 6 have a smaller coefficient of thermal expansion than the incident-side film layer 4. As a result, the warp of the surface film 3 is reduced. For this reason, even if it is a case where it uses for a long time, a high quality image can be maintained, without generating a shift in each subpixel 12b and the concave surface part 8 of the incident side film layer 4. FIG.

As described above, according to the color liquid crystal display 100 of the present embodiment, even when the liquid crystal display panel 1 is thermally deformed due to a temperature rise during long-time use, Since the amount of change in thermal expansion due to thermal deformation of the pixel 12b and the concave surface portion 8 of the incident-side film layer 4 is substantially the same, uneven color and noise of the image due to the influence of heat are prevented, and a high-quality image over a long period of time. Can be maintained.
A color image can be displayed in a state where light transmitted through the sub-pixels 12b constituting the same pixel is uniformly mixed without being mixed.

It is sectional drawing showing schematic structure of the color liquid crystal display of this embodiment.

Explanation of symbols

100 color liquid crystal display
1 Liquid Crystal Display Panel 11 First Panel Layer 11
12 Color filter 13 Second panel layer 12a Support member 12b Subpixel 2 Backlight 2a Circular prism sheet 2b Light guide plate 2c Reflective sheet 3 Surface film 4 Incident side film layer 5 Substrate 6 Output side film layer 7 Diffuse lens 8 Concave surface 8a First 1 concave surface portion 8b second concave surface portion

Claims (6)

A display panel in which one pixel is formed by a plurality of subpixels;
A surface film disposed on the surface of the display panel for diffusing light in each unit pixel;
In an image display device comprising:
The rate of change in thermal expansion length between the front and back surfaces of the surface film is adjusted so that the difference in rate of change in thermal expansion due to the temperature difference between the front and back surfaces of the surface film is substantially zero. An image display device characterized by that. The surface film is composed of three layers: a base material, an incident side film layer positioned on the light incident side surface of the base material, and an output side film layer positioned on the light output side surface of the base material. And
The incident side film layer and the output side film layer are the same material,
The image display apparatus according to claim 1, wherein a thickness of the incident side film layer is smaller than a thickness of the emission side film layer.   The image display device according to claim 1, wherein a rate of change in thermal expansion length of the surface film is the same as a rate of change in thermal expansion length of the display panel.   The image display device according to any one of claims 1 to 3, wherein the display panel is a liquid crystal display panel.   The image display device according to any one of claims 1 to 4, wherein a rate of change in thermal expansion length of the surface film is adjusted by a material or a thickness of the surface film.   The image display apparatus according to claim 1, further comprising a backlight that emits light to the display panel.

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