JP7620114B2 - In-vehicle display panel and display device - Google Patents

Description

The present invention relates to a display panel for an in-vehicle display device that displays information and images such as car navigation systems.

Display panels for in-vehicle display devices that show various information and images are available in either synthetic resin or glass versions. In luxury devices, however, glass versions are often used because the glossy texture of the panel creates a sense of luxury.
The display panel is attached to the front frame of a housing that houses an 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 a display panel to a housing with adhesive tape or the like is cumbersome, requiring the preparation of the adhesive tape required for fixing and adjustments to accurately position the panel. Also, if the display panel becomes scratched or broken and needs to be replaced, it is difficult to do so if it is fixed with adhesive tape or the like.

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

JP 2013-159114 A

When creating a locking portion on the back side of a glass display panel by outsert molding, if the locking portion is thick and wide, the difference in thermal contraction between the glass and the resin can cause the locking portion to not adhere sufficiently to the back side of the display panel, leading to the locking portion being prone to peeling off.

In addition, to improve the design of the glass display panel, it is required to form the display panel into a gently curved shape. For example, if the display panel of a car navigation system is formed into a glossy curved glass shape, it will have an attractive appearance, but in this case, if the display panel is fixed to the front of the housing with adhesive tape, there is a concern that the adhesive tape will gradually peel off during use, causing the display panel to fall off.

To eliminate the concern of the display panel falling off, it is desirable to physically fix the display panel to the housing, for example by providing a locking portion on the back of the display panel and connecting it to a locking portion provided on the housing. However, if the locking portion is thick as described above, the difference in thermal contraction between the glass and the resin makes it easy for the locking portion to be insufficiently fixed. In addition, in an embodiment in which the locking portion is provided on the back surface of thin glass that can be processed into a curved shape by outsert molding, there is also the problem that the thermal contraction of the resin used for the locking portion causes a slight convex bulge on the surface side of the glass directly behind the portion where the locking portion is provided, called "sink mark." The swell on the glass surface appears as a streaky gloss when the display panel reflects external light, which reduces the quality of the appearance of the beautiful curved display panel.

In view of the problems inherent in conventional technology, the present invention aims to provide a display panel for vehicle installation in which a resin molded body is integrally provided on the back side of a thin glass display panel, which serves as an engagement portion for fixing the panel to a housing, and which can be stably fixed to the back side of the display panel without causing any undulations on the surface of the display panel.

In order to solve the above-mentioned problems, the inventors investigated the conditions under which undulations appear on the surface side of the glass when a resin molded body is provided on the back side of the glass that constitutes the display panel. They found that undulations do not appear when the glass is sufficiently thick compared to the thickness of the resin molded body, but that when glass with a thickness of about 0.3 mm is used and a resin molded body is provided on the back side of this, undulations are likely to appear on the surface of the glass even if the thickness of the resin molded body is small.

3 shows the appearance of the front side of a display panel. The illustrated display panel 1 is formed by fixing a resin molded body 3, which is a locking part, to the rear side of a glass substrate 2 having an adhesive layer 22 disposed along the periphery of the rear side of a glass plate 21. The waviness of the glass surface often appears as a convex shape that is high in the center and slightly low around the periphery on the surface of the glass plate 21 directly behind the part where the resin molded body 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 when the resin in contact with the back surface of the glass hardens into the shape of the molded body is stronger than the force (static force of the glass) SF that holds the glass flat, and this contraction force CF acts to cause the portion of the glass where the resin molded body is provided to deform locally 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 undulations that appear on the glass surface.

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 has a weaker static force than the glass, it is expected that the occurrence of swells can be suppressed.
Based on the above-mentioned 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 for vehicle mounting having a configuration in which a resin molded body is provided on at least a part of one of the front and rear sides of a glass substrate,
The resin molded body contains a thermoplastic elastomer, and the resin molded body has a tensile modulus of elasticity of 100 MPa or less and a rubber hardness of 95 or less on the A scale in accordance with JIS-K-6253.
[2] The in-vehicle 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 in-vehicle display panel according to [2], wherein the thickness of the glass substrate is 0.5 mm or less.
[4] The in-vehicle display panel according to any one of [1] to [3], wherein the thermoplastic elastomer is a polyester-based thermoplastic elastomer.
[5] The in-vehicle 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 area on the opposite side of the glass substrate facing the part of the glass substrate where the resin molding is formed is 20 μm or less.
[6] The in-vehicle display panel according to any one of [1] to [5], wherein a printing 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 in-vehicle display panel according to any one of [1] to [6].
The above-mentioned "JIS-K-6253" standard was created based on ISO7619-1.

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

FIG. 2 is a diagram showing the front and back surfaces of a display panel, which is a composite produced in an embodiment, divided. 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. 1 is a graph showing measurement results of an example and a comparative example.

The following describes in detail a preferred embodiment of the present invention, but the present invention is not limited to the following embodiment and can be modified as appropriate within the scope of the gist of the invention.

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

Elastomers are soft polymers with rubber-like elasticity, and resin materials containing them have the characteristics of being easy to process because they are fluid at high temperatures, and having strength 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, and at the same time, the shrinkage force of the resin during molding is small and falls below the static force of the glass, making it possible to suppress undulations on the glass surface.
The tensile modulus of the resin molded body formed of 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 is hard and the contraction force of the resin during molding is also large, so that the static force of the glass is exceeded and undulations are likely to occur on the glass surface. If the tensile modulus is 100 MPa or less, the convex deformation of the glass is suppressed to a small value and the undulations are not noticeable, or the contraction force of the resin is smaller than the static force of the glass, so that undulations can be prevented from occurring. If the tensile modulus is too small, the resin molded body becomes too soft and does not 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 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-described configuration, it is preferable that the thermoplastic elastomer 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 the resin molded body formed of a material containing a thermoplastic elastomer is 95 or less, the resin molded body is appropriately soft, and the contraction force of the resin can be suppressed from being transmitted to the glass at the joint surface between the glass and the resin, and the occurrence of undulations can be prevented. If the rubber hardness is 40 or more, the locking member can have an appropriate hardness. 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 molding is formed on a part of the glass substrate, and that the flatness of a 15 mm square surface of the glass substrate opposite the portion of the glass substrate on which the resin molding is formed is 20 μm or less.
If the flatness of the surface of the glass substrate satisfies the above numerical conditions, undulations are not noticeable in appearance, and there is no effect on the display output of information and images on the display panel.

The in-vehicle display panel of the present invention may have a configuration in which 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 have a black printed layer formed in a stripe along the four peripheral sides of a glass plate having a rectangular shape in a plan view on the back side of the glass plate, an adhesive layer laminated on the surface of the printed layer, and a resin molded body formed on the adhesive layer.

The ink for forming the print layer may be any ink that can be directly printed on a glass plate, and any ink commercially available for printing on glass plates may be used.
From the viewpoint of adhesion to glass, an ink containing a silane coupling agent is preferred.
The ink is used by incorporating 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 surface of the glass plate preferably has a thickness of 0.2 mm or more and 2.0 mm or less, and more preferably has a thickness of 0.5 mm or less in applications where the glass is curved and fixed in a curved shape.
If the thickness is 2.0 mm or less, the weight of the in-vehicle display panel can be reduced, and the load on the locking portion can be suppressed, which is preferable. Also, the sensitivity of the sensor attached to the back surface of the display panel can be improved, which is preferable.
If the thickness is 0.5 mm or less, the glass substrate can be processed to have a curved shape and can be installed in a housing while maintaining the curved shape, which is preferable. If the thickness is 0.2 mm or more, the glass substrate is less likely to break even when curved.

Examples of the glass substrate include borosilicate glass, aluminosilicate glass, aluminoborosilicate glass, etc. Examples of the glass substrate include low-alkali glass and non-alkali glass of these glasses, etc. Examples of the glass substrate further include silica glass and soda-lime glass, etc. Among these, borosilicate glass, aluminosilicate glass, aluminoborosilicate glass, and low-alkali glass of these glasses are preferred, and non-alkali glass of these glasses is 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 uses a resin containing a thermoplastic elastomer as a material, and it is more preferable to use a thermoplastic elastomer.
Examples of the thermoplastic elastomer used in the resin molded body 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 as long as the tensile modulus is 100 MPa or less. Examples of the thermoplastic resin include ABS resin, polypropylene resin, polyamide resin, polycarbonate resin, POM resin, PMMA resin, PBT resin, and PC-ABS resin.

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 for embodying the technical concept of the present invention, and the present invention is not limited to the forms described below.

An in-vehicle display panel according to the present invention shown in FIG. 1 was produced.
This display panel 1 is formed with the expectation that it will be used as a display panel for car navigation, 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 a strip shape along the four peripheral sides of the back side of a 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 on a printed layer 22a provided on the back side of the glass substrate 2. In detail, 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, and after the printed layer 22a dries, a two-component curing polyurethane ink is applied to its surface and dried, and the adhesive layer 22b is laminated on the upper surface of the printed layer 22a.

The resin molding 3 is fixed to the rear surface of the glass substrate 2 at three locations: the center of the upper edge and the lower parts of the left and right edges. The material used for the resin molding 3 was changed to perform a performance evaluation, including whether or not undulations appeared on the surface of the display panel 1.

Example 1
Thermoplastic polyester elastomer "Hytrel (registered trademark) 4047N" (Toray DuPont Co., Ltd.) was used as the material for the resin molded body, and the resin molded body 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 produced 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 Tohoku Industrial Technology Center. The measured rubber hardness was 92 in the first measurement and 93 in the second measurement.
In addition, 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 material used was determined by carrying out a tensile test in accordance with JIS K 6251: 2010. Note that a dumbbell-shaped No. 2 test piece was used.
3, the flatness of the glass substrate of the display panel 1 was measured on the rear side of the resin molded body 3 arranged at the center of the upper side of the rear side of the display panel 1, that is, on the front side of the glass substrate of the display panel 1, in a 15 mm square area centered on the center of the resin molded body 3. The flatness was measured using a "Surface Roughness/Contour Shape Measuring Instrument Form Tracer Avant FTA-D4000" (Mitutoyo Corporation). The measurement using this measuring instrument was in accordance with the surface quality evaluation of JIS B 0633:2001 and JIS B 0651:2001.
In addition, the presence or absence of waviness on the surface of the manufactured display panel was visually confirmed.
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 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 produced in the same manner as in Example 1 had a rubber hardness of 83 in the first measurement using the fully automatic micro rubber hardness tester, and 84 in the second measurement. The rubber hardness was also measured using the durometer and was 86.

Example 3
A thermoplastic polyester elastomer "TEFABLOCK (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 produced in the same manner as in Example 1 had a rubber hardness of 60 in the first measurement using the fully automatic micro rubber hardness tester, and 76 in the second measurement. The rubber hardness was also measured using the durometer and was 78.

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

Example 5
A thermoplastic polyester elastomer "TEFABLOCK (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 produced in the same manner as in Example 1 had a rubber hardness of 43 the first time measured by the fully automatic micro rubber hardness tester, and the rubber hardness of 43 the second time measured by the fully automatic micro rubber hardness tester. The rubber hardness was also 43 when measured by the durometer.

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 resin molded article had a first rubber hardness of 99 and a second rubber hardness of 99 measured with a fully automatic micro rubber hardness tester. The rubber hardness was also measured with a durometer and was 99.

Comparative Example 2
A thermoplastic polyester elastomer "Hytrel (registered trademark) 5557" (Toray DuPont Co., Ltd.) 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 produced in the same manner as in Example 1 had a rubber hardness of 97 in the first measurement using the fully automatic micro rubber hardness tester, and 98 in the second measurement. The rubber hardness was also measured using the durometer and was 98.

In the "Waviness Evaluation" section of Table 1, if the waviness was not noticeable at all when visually checked, it was marked as "O", if it was slightly noticeable, it was marked as "△", and if it was noticeable, it was marked as "X".

Figure 5 shows a graph showing the relationship between the elastic modulus of 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 "Example 1" to "Example 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 when looking closely in Example 1, but the waviness was small and only slightly bothersome. Moreover, 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 of the examples and the comparative examples, it was found that the appearance of the slightly bothersome undulations as in Example 1 was not impaired even when used in a car navigation display panel, and therefore there was no practical problem.

According to the results of visually inspecting the above-mentioned ripples, 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 ripples that occur on the display panel less noticeable to the point that they are not bothersome.
Furthermore, as shown in the graph of FIG. 5, it is estimated that if the elastic modulus of the material used is 100 MPa or less, preferably 68 MPa or less which is the elastic modulus of the material of Example 1, it is possible to make the ripples occurring in the display panel less noticeable to the point that they are not noticeable, or to prevent the ripples from occurring at all.
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 ripples that occur in the display panel less noticeable to the point that they are not noticeable, or to prevent the ripples 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 according to the display device, and an appropriate number of resin molded bodies are provided on the back side of the glass substrate, and are provided at appropriate positions on the back side of the glass substrate according to the size of the display device.
The shapes and combinations of the glass substrate and the resin molded body constituting the composite of the present invention are merely examples, and various modifications can be made based on design requirements and the like without departing from the spirit of the present invention.

REFERENCE SIGNS LIST 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 for vehicle mounting having a configuration in which a resin molded body serving as a locking portion, such as a rib 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 according to JIS-K-6253 ;
The thickness of the glass substrate is 0.2 mm or more and 2.0 mm or less . 2. The vehicle-mounted display panel according to claim 1 , wherein the glass substrate has a thickness of 0.5 mm or less. The in-vehicle display panel according to claim 1 or 2, wherein the thermoplastic elastomer is a polyester-based thermoplastic elastomer. The in-vehicle display panel according to claim 1 or 2, in which the resin molded body is formed on a part of the glass substrate, and the flatness of a 15 mm square on the surface of the glass substrate opposite the part on which the resin molded body is formed is 20 μm or less. The in-vehicle display panel according to claim 1 or 2, in which a print layer and an adhesive layer are laminated on a glass substrate, and a resin molded body is disposed on the adhesive layer. A display device comprising the in-vehicle display panel according to claim 1 or 2.

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