JP7799090B2 - Display panel and display device - Google Patents

Description

The present invention relates to a display panel of a display device that displays information and images for car navigation and the like.

Display panels for in-vehicle display devices that display various information and images are made of synthetic resin or glass, but glass panels are often used in high-end devices because the glossy texture of the panel creates a sense of luxury.
The display panel is attached to the front frame of the housing that houses the electronic device, and in many cases, the back side of the glass display panel is attached to the front frame using adhesive tape or the like.

The method of attaching and fixing the display panel to the housing using adhesive tape or similar is cumbersome, requiring the preparation of the adhesive tape needed for fixing and the adjustments required to accurately position the panel. Furthermore, if the display panel becomes scratched or damaged and needs to be replaced, it can be difficult to do so if it is fixed with adhesive tape or similar.

Instead of the above-mentioned adhesive fixing method, a method is being considered in which a locking portion such as a rib made of a resin material is integrally attached to the back side of the glass display panel by outsert molding, and the locking portion is then joined to a locking portion provided on the front frame of the housing to attach the display panel to the housing (see, for example, Patent Document 1).

JP 2013-159114 A

When using outsert molding to create a locking portion on the back side of a glass display panel, if the locking portion is thick and wide, the difference in thermal contraction between the glass and resin can cause the locking portion to not adhere properly to the back side of the display panel, resulting in the locking portion easily peeling off.

Furthermore, to enhance the design of such glass display panels, there is a demand for them to be formed into gently curved shapes. For example, forming a car navigation display panel into a glossy curved glass surface would give it an attractive appearance, but in this case, if the display panel were fixed to the front of the housing with adhesive tape, there is a concern that the adhesive tape may gradually peel off during use, causing the display panel to fall off.

To eliminate the risk of the display panel falling, it is desirable to physically secure the display panel to the housing. For example, it is desirable to provide a locking portion on the back of the display panel, which is then connected to a locking portion on the housing. However, if the locking portion is thick, as described above, the difference in thermal contraction between the glass and the resin can easily result in insufficient adhesion of the locking portion. Furthermore, in cases where the locking portion is provided on the back of thin glass that can be processed into a curved shape using outsert molding, there is a problem in that the thermal contraction of the resin used for the locking portion can cause a slight convex bulge (sink mark) on the surface of the glass directly behind the portion where the locking portion is provided. When the display panel reflects external light, the undulations on the glass surface appear as streaky gloss, which degrades the appearance of the beautifully curved display panel.

In view of the problems inherent in conventional technology, the present invention aims to provide a display panel in which a resin molding is integrally formed on the back side of a thin glass display panel, serving as a locking portion for fixing the panel to a housing, and to enable the resin molding to be stably fixed to the back side of the display panel without causing any undulations to appear on the surface of the display panel.

In order to solve the above-mentioned problem, the inventors investigated the conditions under which undulations would appear on the surface of the glass when a resin molded body was placed on the back surface of the glass that constitutes the display panel. They found that undulations would not appear if the glass was sufficiently thick compared to the thickness of the resin molded body, but that when glass with a thickness of approximately 0.3 mm was used and a resin molded body was placed on the back surface, undulations were likely to appear on the surface of the glass even if the resin molded body was thin.

3 shows the appearance of the front side of a display panel. The illustrated display panel 1 is formed by fixing a resin molding 3, which serves as a fastening portion, to the rear surface of a glass substrate 2 having an adhesive layer 22 disposed along the periphery of the rear surface of a glass plate 21. The waviness of the glass surface often appears as a convex shape, higher in the center and slightly lower around the periphery, on the surface of the glass plate 21 directly behind the portion where the resin molding 3 is fixed.
As shown in Figure 4, when the glass is thin, the contraction force (amount of contraction) CF of the resin that is applied to the back surface of the glass as the resin in contact with the back surface hardens into the shape of the molded body is greater than the force that holds the glass flat (static force of the glass) SF, and this contraction force CF acts to locally deform the portion of the glass where the resin molded body is provided into a convex shape (the portion indicated by the dashed line in the figure), and it is presumed that this convex deformation is the cause of the waviness that appears on the surface of the glass.

According to this speculation, if the contraction force of the resin is smaller than the static force of the glass, or if the resin itself is weaker than the static force of the glass, it is expected that the occurrence of undulations can be suppressed.
Based on the above findings and assumptions, the inventor selected the material to be used for the resin molding, and verified whether the resin molding could be fixed to glass with a contraction force smaller than the static force of the glass, thereby completing the present invention.

That is, the gist of the present invention is as follows.
[1] A display panel having a configuration in which a resin molding is provided on at least a part of one of the front and rear surfaces of a glass substrate,
The display panel is characterized in that the resin molded body contains a thermoplastic elastomer, the tensile modulus of the resin molded body is 100 MPa or less, and the rubber hardness on the A scale in accordance with JIS-K-6253 is 95 or less.
[2] The display panel according to [1], wherein the thickness of the glass substrate is 0.2 mm or more and 2.0 mm or less.
[3] The display panel according to [2], wherein the thickness of the glass substrate is 0.5 mm or less.
[4] The display panel according to any one of [1] to [3], wherein the thermoplastic elastomer is a polyester-based thermoplastic elastomer.
[5] The display panel according to any one of [1] to [4], wherein the resin molding is formed in a part of the glass substrate, and the flatness of a 15 mm square on the surface of the glass substrate opposite to the part where the resin molding is formed is 20 μm or less.
[6] The display panel according to any one of [1] to [5], wherein a print layer and an adhesive layer are laminated on a glass substrate, and a resin molded body is disposed on the adhesive layer.
[7] A display device comprising the display panel according to any one of [1] to [6].
The above-mentioned "JIS-K-6253" standard was created based on ISO7619-1.

With the in-vehicle display panel of the present invention, even when a resin molded body such as a locking portion for fixing to the housing is integrally provided on the back side of a thin glass display panel, the resin molded body can be stably fixed to the back side of the display panel without causing any undulations on the surface of the display panel.

1 is a diagram showing the front and back surfaces of a display panel, which is a composite manufactured in an example, divided into parts. 2 is an enlarged cutaway perspective view of a portion of the display panel of FIG. 1 where a resin molded body is provided. FIG. 2 is an enlarged external view of the front side of the display panel of FIG. 1. FIG. 4 is an enlarged cross-sectional view taken along line IV-IV in FIG. 3. 1 is a graph showing measurement results of an example and a comparative example.

The following describes in detail preferred embodiments of the present invention, but the present invention is not limited to the following embodiments and can be modified and implemented as appropriate within the scope of its essence.

As described above, the present invention relates to an in-vehicle display panel having a configuration in which a resin molded body is provided on at least a portion of one of the front and rear surfaces of a glass substrate, and the resin molded body contains a thermoplastic elastomer, and is characterized by having a tensile modulus of elasticity of 100 MPa or less and a rubber hardness of 95 or less on the A scale according to JIS-K-6253.

Elastomers are soft polymers with rubber-like elasticity, and resin materials containing them are fluid at high temperatures, making them easy to process, and they have the characteristic of being strong even without fillers. By forming the resin molded body, which is the aforementioned locking portion, from a material containing a thermoplastic elastomer, the resin molded body can be stably fixed to the glass surface. In addition, the shrinkage force of the resin during molding is small, and is lower than the static force of the glass, making it possible to suppress the occurrence of undulations on the glass surface.
The tensile modulus of elasticity of a resin molded body formed from a material containing a thermoplastic elastomer is preferably 100 MPa or less. If the tensile modulus is greater than 100 MPa, the resin molded body will be hard, and the shrinkage force of the resin during molding will also be large, which will exceed the static force of the glass and make it more likely that undulations will occur on the glass surface. If the tensile modulus is 100 MPa or less, the convex deformation of the glass will be kept small, making the undulations less noticeable, or the shrinkage force of the resin will be smaller than the static force of the glass, preventing undulations from occurring. If the tensile modulus is too small, the resin molded body will be too soft and will no longer function as a locking portion, making it difficult to physically fix the display panel to the housing of the display device. Therefore, the lower limit of the tensile modulus of elasticity of the resin molded body is preferably 2 MPa or more, more preferably 9 MPa or more, and the upper limit is preferably 70 MPa or less, more preferably 50 MPa or less.

In the in-vehicle display panel having the above configuration, the thermoplastic elastomer preferably has a rubber hardness of 95 or less.
The rubber hardness referred to here means the rubber hardness on the A scale in accordance with JIS-K-6253.
If the rubber hardness of a resin molded body formed from a material containing a thermoplastic elastomer is 95 or less, the resin molded body is appropriately soft, and the transmission of the contraction force of the resin to the glass at the joint surface between the glass and the resin can be suppressed, preventing the occurrence of undulations. If the rubber hardness is 40 or more, the resin molded body has an appropriate hardness for use as a locking member. The lower limit of the rubber hardness is preferably 50 or more, and more preferably 55 or more. The upper limit is preferably 85 or less, and more preferably 80 or less.

Furthermore, it is preferable that the resin molded body is formed on a part of the glass substrate, and that the flatness of a 15 mm square area on the surface of the glass substrate opposite the part where the resin molded body is formed is 20 μm or less.
If the flatness of the surface of the glass substrate satisfies the above numerical conditions, undulations will not be noticeable in appearance, and there will be no effect on the display output of information and images on the display panel.

The in-vehicle display panel of the present invention can be configured such that a print layer and an adhesive layer are laminated on a glass substrate, and a resin molded body is disposed on the adhesive layer.
For example, when the in-vehicle display panel of the present invention is a display panel for car navigation, the glass substrate can be formed by forming a black printed layer in a strip shape along the four peripheral sides of a glass plate that is rectangular in plan view on the back side of the glass plate, laminating an adhesive layer on the surface of this printed layer, and forming a resin molded body on this adhesive layer.

The ink for forming the printing layer may be any ink that can be used for direct printing on a glass plate, and commercially available inks for printing on glass plates can be used.
From the viewpoint of adhesion to glass, ink containing a silane coupling agent is preferred.
The ink contains a black colorant such as carbon black, and the printed layer forms a black colored portion on the surface of the glass plate.

The adhesive layer may be any adhesive that can bond the printed layer to the resin molded body to be outsert molded.
Furthermore, commercially available binder inks and adhesion enhancers for use in injection molding can also be used.

The glass substrate having a printed layer and an adhesive layer laminated on one side of the glass plate preferably has a thickness of 0.2 mm or more and 2.0 mm or less, and more preferably 0.5 mm or less in applications where glass is curved and held in a curved shape while being fixed.
If the thickness is 2.0 mm or less, the weight of the in-vehicle display panel can be reduced, the load on the locking portion can be reduced, and the sensitivity of the sensor bonded to the back surface of the display panel can be improved.
A thickness of 0.5 mm or less is preferable because the glass substrate can be processed to have a curved shape and can be installed in a housing while maintaining the curved shape, whereas a thickness of 0.2 mm or more is preferable because the glass substrate is less likely to break even when curved.

Examples of the glass substrate include borosilicate glass, aluminosilicate glass, and aluminoborosilicate glass. Also included are low-alkali and non-alkali glasses of these glasses. Further examples include silica glass and soda-lime glass. Among these, borosilicate glass, aluminosilicate glass, aluminoborosilicate glass, and low-alkali glasses thereof are preferred, and non-alkali glasses thereof are more preferred.
The glass substrate may be colorless or colored, but is preferably colorless and transparent in order to improve the visibility of the display.

The resin molded body is made of a resin containing a thermoplastic elastomer, and it is more preferable to use a thermoplastic elastomer.
Examples of the thermoplastic elastomer used in the resin molded article include styrene-based elastomers, vinyl chloride-based elastomers, olefin-based elastomers, urethane-based elastomers, polyester-based elastomers, nitrile-based elastomers, polyamide-based elastomers, etc. From the viewpoint of adhesion to the adhesive layer, styrene-based elastomers, urethane-based elastomers, and polyester-based elastomers are preferred, and among these, polyester-based elastomers are more preferred.
Although the resin molded product is preferably a thermoplastic elastomer alone, it may contain one or more known thermoplastic resins, such as ABS resins, polypropylene resins, polyamide resins, polycarbonate resins, POM resins, PMMA resins, PBT resins, and PC-ABS resins, as long as the tensile modulus of the resin is 100 MPa or less.

The in-vehicle display panel of the present invention can be used as a display panel for devices that display various types of information and images. Examples of display devices include car navigation systems, meter panels, and heater controllers.

The following describes the in-vehicle display panel of the present invention based on examples. However, the examples shown below are merely examples intended to embody the technical concept of the present invention, and the present invention is not limited to the embodiments described below.

An in-vehicle display panel according to the present invention shown in FIG. 1 was produced.
This display panel 1 is designed to be used as a display panel for car navigation systems, and is constructed by arranging a resin molding 3, which serves as a fastening portion, integrally on the back side of a rectangular glass substrate 2.

As shown in Figures 1 and 2, the glass substrate 2 has a black colored portion 22 in the form of a strip along the four periphery of the back side of the transparent glass plate 21, and is formed to an overall thickness of approximately 0.5 mm.

The colored portion 22 is formed by laminating an adhesive layer 22b onto a printed layer 22a provided on the back side of the glass substrate 2. Specifically, the printed layer 22a is formed by applying an ink made of an acrylic urethane resin containing a silane coupling agent in a frame shape along the periphery of the back side of the glass plate 21. After the printed layer 22a has dried, a two-component curing polyurethane ink is applied to its surface and dried, and the adhesive layer 22b is laminated on top of the printed layer 22a.

The resin molding 3 is fixed to the rear surface of the glass substrate 2 in three locations: the center of the top edge and the lower parts of the left and right edges. By changing the material used for the resin molding 3, performance evaluations were conducted, including whether or not undulations appeared on the surface of the display panel 1.

Example 1
The resin molding material was a thermoplastic polyester elastomer "Hytrel (registered trademark) 4047N" (Toray DuPont Co., Ltd.), and the resin molding was integrally fixed to the back surface of the glass substrate by injection molding to produce a display panel.

Using this material, a plate sample having a length and width of 100 mm x width of 100 mm and a thickness of 2 mm was prepared by injection molding.
The rubber hardness of the prepared samples was measured using a fully automatic micro rubber hardness tester "Model MD-1 Type A, JIS A approximation value" (Kobunshi Keiki Co., Ltd.) owned by the Shiga Prefecture Northeast Industrial Technology Center. The measured rubber hardness was 92 in the first measurement and 93 in the second measurement.
Furthermore, the rubber hardness of the prepared sample was measured in accordance with JIS-K-6253 using a durometer type A. The measured rubber hardness was 94.

The elastic modulus of the materials used was determined by a tensile test in accordance with JIS K 6251: 2010. Dumbbell-shaped No. 2 test pieces were used.
For the manufactured display panel, as shown in Figure 3, the flatness of a 15 mm square glass substrate centered on the center of the resin molded body 3 on the front surface side of the glass substrate of the display panel 1 was measured directly behind the resin molded body 3 arranged in the center of the upper edge of the back surface of the display panel 1. The flatness was measured using a "Surface Roughness and Contour Shape Measuring Instrument Formtracer Avant FTA-D4000" (Mitutoyo Corporation). The measurement using this measuring instrument complies with the surface quality evaluation standards JIS B 0633:2001 and JIS B 0651:2001.
Furthermore, it was visually confirmed whether or not undulations appeared on the surface of the manufactured display panel.
The above measurement results and confirmation results are shown in Table 1.

Example 2
A thermoplastic polyester elastomer "Hytrel (registered trademark) 3001" (Toray DuPont Co., Ltd.) was used as the material for the resin molding, and a display panel was produced in the same manner as in Example 1, and the same measurements and confirmations were carried out.
The sample prepared in the same manner as in Example 1 was measured with the fully automatic micro rubber hardness tester, and the rubber hardness in the first measurement was 83, and the rubber hardness in the second measurement was 84. The rubber hardness measured with the durometer was 86.

Example 3
A thermoplastic polyester elastomer "TEFABLOC (registered trademark) A1700N" (Mitsubishi Chemical Corporation) was used as the material for the resin molded body, and a display panel was produced in the same manner as in Example 1, and the same measurements and confirmations were carried out.
The sample prepared in the same manner as in Example 1 was measured with the fully automatic micro rubber hardness tester, and the rubber hardness was 60 in the first measurement and 76 in the second measurement. The rubber hardness was also measured with the durometer and was 78.

Example 4
A thermoplastic polyester elastomer "TEFABLOC (registered trademark) A1600N" (Mitsubishi Chemical Corporation) was used as the material for the resin molded body, and a display panel was produced in the same manner as in Example 1, and the same measurements and confirmations were carried out.
The sample prepared in the same manner as in Example 1 was measured with the fully automatic micro rubber hardness tester, and the rubber hardness in the first measurement was 53 and the rubber hardness in the second measurement was 66. The rubber hardness measured with the durometer was 69.

Example 5
A thermoplastic polyester elastomer "TEFABLOC (registered trademark) A1400N" (Mitsubishi Chemical Corporation) was used as the material for the resin molded body, and a display panel was produced in the same manner as in Example 1, and the same measurements and confirmations were carried out.
The sample prepared in the same manner as in Example 1 was measured with the fully automatic micro rubber hardness tester, and the rubber hardness was 43 the first time and 43 the second time. The rubber hardness was also measured with the durometer and was 47.

Comparative Example 1
A thermoplastic polyester elastomer, "Hytrel (registered trademark) 7247" (Toray DuPont Co., Ltd.), was used as the material for the resin molded body, and an attempt was made to manufacture a display panel similar to that of Example 1. However, the resin molded body peeled off from the glass substrate and could not be fixed.
The rubber hardness of the resin molded article measured by a fully automatic micro rubber hardness tester was 99 in the first measurement and 99 in the second measurement. The rubber hardness measured by a durometer was also 99.

Comparative Example 2
A thermoplastic polyester elastomer "Hytrel (registered trademark) 5557" (Toray DuPont Co., Ltd.) was used as the material for the resin molding, and a display panel was produced in the same manner as in Example 1, and the same measurements and confirmations were carried out.
The sample prepared in the same manner as in Example 1 was measured with the fully automatic micro rubber hardness tester, and the rubber hardness in the first measurement was 97, and the rubber hardness in the second measurement was 98. The rubber hardness measured with the durometer was also 98.

In the "Waviness Evaluation" section of Table 1, if the waviness was not noticeable when visually checked, a "Good" was marked; if it was slightly noticeable, a "Good" was marked; and if it was noticeable, an "Unclear" was marked.

Figure 5 shows a graph showing the relationship between the modulus of elasticity for each material and the measured flatness of the glass of the display panel in each Example and Comparative Example 2. In the figure, "Ex. 1" to "Ex. 5" refer to Examples 1 to 5, and "Comp. 2" refers to Comparative Example 2.

As shown in Table 1, when the presence and condition of waviness on the surface of the display panel was visually confirmed, waviness was clearly observed in Comparative Example 2, and waviness was confirmed by looking closely in Example 1, but the waviness was small and only slightly bothersome. Furthermore, in Examples 2 to 5, waviness was not noticeable at all, and no waviness was confirmed by visual inspection.
From the observation of the display panels of each example and comparative example, it was found that the appearance of the undulations, which were only slightly noticeable in example 1, would not be impaired even when used in a car navigation display panel, and would not pose any practical problems.

According to the results of visually inspecting the above-mentioned waviness, it is estimated that if the rubber hardness of the material used for the resin molding is 95 or less, which is less than that of the material in Comparative Example 2 and slightly greater than that of the material in Example 1, it will be possible to make the waviness that occurs on the display panel less noticeable to the point where it is not noticeable.
Furthermore, as shown in the graph of FIG. 5, it is estimated that if the modulus of elasticity of the material used is 100 MPa or less, preferably 68 MPa or less, which is the modulus of elasticity of the material of Example 1, it will be possible to make the undulations that occur on the display panel less noticeable or to prevent the undulations from occurring.
Furthermore, if the flatness of the display panel is 20 μm or less, preferably 15 μm or less, which is the flatness measured in Example 1, it is estimated that it is possible to make the waviness that occurs on the display panel less noticeable to the point that it is not noticeable, or to prevent the waviness from occurring at all.

In the above embodiment, the composite of the present invention is applied to the display panel of a car navigation system, but it can also be applied to the display panel of other information display devices. In this case, the display panel is formed to a size corresponding to the display device, and an appropriate number of resin molded bodies are provided on the back surface of the glass substrate at appropriate positions on the back surface of the glass substrate according to the size of the display device.
The shapes and combinations of the glass substrate and resin molded body that constitute the composite of the present invention are merely examples, and various modifications can be made based on design requirements and the like within the scope of the present invention.

1. In-vehicle display panel, 2. Glass substrate, 21. Glass plate, 22. Colored portion, 22a. Printed layer, 22b. Adhesive layer, 3. Resin molded body

Claims (6)

A display panel having a configuration in which a resin molding that serves as a locking portion, such as a rib, that is connected to a locking portion of a housing is provided on one of both front and rear side surfaces of a glass substrate,
the resin molded body contains a thermoplastic elastomer, the resin molded body has a tensile modulus of elasticity of 2 MPa or more and 100 MPa or less , and a rubber hardness of 95 or less on the A scale in accordance with JIS-K-6253,
A display panel characterized in that the thickness of the glass substrate is 0.2 mm or more and 2.0 mm or less . 2. The display panel according to claim 1 , wherein the thickness of the glass substrate is 0.5 mm or less. 3. The display panel according to claim 1, wherein the thermoplastic elastomer is a polyester-based thermoplastic elastomer. 3. A display panel according to claim 1, wherein the resin molding is formed in a part of the glass substrate, and the flatness of a 15 mm square area on the opposite side of the glass substrate opposite the part of the glass substrate where the resin molding is formed is 20 μm or less. 3. The display panel according to claim 1, wherein a print layer and an adhesive layer are laminated on a glass substrate, and the resin molded body is disposed on the adhesive layer. A display device comprising the display panel according to claim 1 or 2.