DE112015003842T5 - On-board display device - Google Patents

Abstract

Provided is an on-board display device having a cover glass with excellent impact resistance. The on-board display device is formed by laminating elements from a surface layer cover glass as a first layer to an n-th layer, the cover glass being a reinforced glass having a plate thickness of 0.5 to 2.5 mm and a depth of a surface compression stress layer of at least 10 μm, and the device satisfies the specific formula (I).

Description

Technical area

The present invention relates to an on-board display device.

background

In order to protect a display panel such as a liquid crystal panel, a transparent protective member covering the display surface (display panel) of the display panel has hitherto been used. As a protective member for protecting such a display device, for example, according to Patent Document 1, there is disclosed a transparent surface material attached via an adhesive layer, which has an adhesive layer on the surface.

Reference to the prior art

Patent Document

• Patent Document 1: WO2011 / 148990

Disclosure of the invention

Technical problem

On a vehicle, such as a motor vehicle, an on-board display device, such as a car navigation device, is mounted. The type of on-board display device may be, for example, the dashboard type where mounting is outside the instrument panel, or the dashboard type where it is embedded in the instrument panel.

In addition, in such an on-board display device, a transparent protective member such as a film or glass is used for the purpose of protecting the display panel. However, in recent years, it was desirable to use a glass protective element (cover glass) instead of a film because of texture. For glass materials, however, laminated glass tends to be thick and is likely to have design problems and high costs, and therefore the use of reinforced glass is desired.

For the sake of safety, a cover glass is required for an on-board display device in which an excellent impact resistance is provided so that it does not break even if the head of an occupant or the like strikes in a collision of the vehicle. The collision in a rear-end collision has some energy that is much greater than the shock expected, for example, in a stationary-type display device such as an LCD TV, for which reason the cover glass requires good impact resistance.

The present invention has been made in consideration of the above points, and an object of the invention is to provide an on-board display device in which the cover glass has excellent impact resistance.

the solution of the problem

The on-board display device according to an embodiment of the present invention is an on-board display device formed by laminating elements of a surface layer cover glass as a first layer to an n-th layer, the cover glass being a reinforced glass having a plate thickness of 0.5 to 2.5 mm and a thickness of a surface compression stress layer of at least 10 μm, and the on-board display device satisfies the following formula (I): P <= 0.0302t ₁ ² + 0.0039t ₁ + 0.0478 Formula (I)

Here, in the formula (I), P = E ₁ / (E ₁ t ₁ ² + ... + E _n t _n ² ), E _{1 is} the Young's modulus of the cover glass (unit: GPa), t ₁ the thickness of the cover glass (unit: mm) is, E _n the Young's modulus of the element n-th layer (unit: GPa), and t _{n is} the thickness of the n-th layer (unit: mm), where n is an integer of at least the second

Advantageous Effects of the Invention

According to the present invention, it is possible to provide an on-board display device having a cover glass excellent in impact resistance.

Brief description of the drawing

1 FIG. 12 is a schematic sectional view illustrating a cover glass attached via an adhesive layer. FIG.

2 is a schematic sectional view showing an on-board display device.

3 FIG. 12 is a schematic diagram illustrating a four-layered structure. FIG.

4 is a perspective view showing a test specimen.

5 is a cross-sectional view along a line AA of 4 ,

6 is a plan view showing the test specimen.

7 is a graph obtained by printing evaluation results of impact resistance.

Description of embodiments

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings. However, the present invention is not limited to the following embodiment. Rather, without departing from the scope of the present invention, various modifications or substitutions may be made to the following embodiment.

Hereinafter, a cover glass attached via an adhesive layer for use with the on-board display device of the present embodiment will first be described, and then the on-board display device of the present embodiment will be described.

Cover glass applied over an adhesive layer

1 FIG. 12 is a schematic sectional view illustrating a cover glass attached via an adhesive layer. FIG. In the present embodiment, as an example of a method of manufacturing an on-board display device, there is shown an embodiment for producing a cover glass attached via an adhesive layer and connecting it to a display panel. However, the method of manufacturing an on-board display device is not limited thereto. The cover glass and the display panel can be connected via an OCA (Optically Clear Adhesive OCA) film.

The cover glass attached via an adhesive layer 10 as shown in 1 has a transparent cover glass 12 , an adhesive layer 14 , a protective film 16 and a light shielding portion 20 ,

The adhesive layer 14 is on the cover glass 12 intended. In the cover glass 12 becomes the surface on which the adhesive layer 14 is to be provided, floor space 12a called. In the cover glass 12 is the light-shielding section 20 at the peripheral portion 12b formed, and the adhesive layer 14 is at the first main surface 12c of the cover glass 12 educated.

The shapes of the cover glass 12 and the adhesive layer 14 are, for example, rectangular when viewed in plan view, with the adhesive layer 14 is smaller in outer shape. The adhesive layer 14 is on the cover glass 12 for example, such that it is tuned to the center, arranged. In the first main surface 12c of the cover glass 12 is along the peripheral portion 12b at the periphery of the available area 12a the light shielding section 20 formed in the form of a frame.

The light-shielding section 20 serves to conceal a wiring member and the like connected to the display panel except for the display surface (display surface) of the display panel, as will be described later, from that of the second main surface 12d to the own side of the cover glass 12 can not be visually perceived. In the case of a structure in which, for example, a wiring member and the like can not be optically perceived from the observation side of the display panel, the light-shielding portion needs to be 20 not necessarily be provided.

At the first main surface 14a the adhesive layer 14 is a protective film 16 to cover the entire surface of the coverslip 12 provided so that it can be deducted. At the time of bonding the cover glass attached via an adhesive layer 10 with the on-board display device, the protective film becomes 16 deducted. In such a case, for example, a cutting line is in the first main surface 16a of the protective film 16 trained, and it becomes the protective film 16 deducted. The protective film 16 is not particularly limited, and for example, a comparatively soft film of polyethylene, polypropylene and the like can be used more.

cover glass

The cover glass 12 serves to protect the display surface (display surface) of the on-board display device, and is usually a plate-like body (glass plate) having a flat or curved surface.

The plate thickness of the cover glass 12 ranges from 0.5 to 2.5 mm. If the plate thickness is less than 0.5 mm, then the thickness of the cover glass 12 itself tends to be inadequate, and the impact resistance of the coverslip attached via an adhesive layer is likely to decrease 10 , Furthermore, if the panel thickness exceeds 2.5 mm, it tends to be too large and becomes unsuitable for use with an on-board display device in view of the design.

The outline or size of the cover glass 12 is generally larger than the display panel in view of the design, mounting of a sensor, or mounting to a display module. The shape of the cover glass 12 is appropriately determined in view of the design so as to be attuned to the on-board display device. The on-board display device may have various shapes, such as rectangular, trapezoidal, and the like, in which case the outer shape of the coverslip 12 often equivalent to the outer shape of the on-board display device. Depending on the external shape of the on-board display device, it is possible to use a cover glass 12 to use, which has a shape that covers the entire surface of the display device of the display panel and having a curved shape containing outer shape.

Mention may be made of an example of the size of the coverslip 12 For example, the case of a rectangular shape with 10 to 800 mm in the longitudinal direction and 40 to 300 mm in the transverse direction.

Is used in the present embodiment as a cover glass 12 a plate-shaped reinforced glass which has undergone a reinforcing treatment used, for example, in colorless and transparent soda-lime glass or aluminosilicate glass (SiO ₂ -Al ₂ O ₃ -Na ₂ O-type glass).

As a cover glass 12 It is preferable to use a chemically strengthened glass (for example, "Dragon Trail (Registered Trade Mark)" manufactured by Asahi Glass Co. Ltd.) which has undergone an ion exchange strengthening treatment used, for example, in aluminosilicate glass.

As the cover glass 12 forming glass material can be used here, for example, a glass material with, based on mole percent, 50 to 80% of SiO ₂ , 1 to 20% of Al ₂ O ₃ , 6 to 20% of Na ₂ O, 0 to 11% of K ₂ O. , 0 to 15% of MgO, 0 to 6% of CaO and 0 to 5% of ZrO ₂ .

On each surface of the chemically amplified coverslip 12 a compression stress layer is formed, wherein the depth of the surface compression stress layer is at least 10 μm, preferably at least equal to 15 μm, more preferably at least equal to 25 μm, and most preferably at least equal to 30 μm. Further, the surface compression load in the surface compression stress layer is preferably at least 650 MPa, and more preferably at least 750 MPa.

The method of applying the chemical amplification treatment to the coverslip 12 is usually a process in which the coverslip 12 is immersed in a molten KNO ₃ salt for ion exchange treatment and then cooled to about room temperature. The treatment parameters, such as the temperature of the molten KNO ₃ salt, the immersion time, and the like, may be selected such that the surface compression load and the depth of the surface compression stress layer have the desired values.

adhesive layer

The adhesive layer 14 serves to connect the cover glass 12 with an on-board display device at the time of connection of the cover glass 12 with the on-board display device. The adhesive layer 14 is like the coverslip 12 preferably transparent, wherein the difference in the refractive index between the cover glass 12 and the adhesive layer 14 preferably as small as possible.

The adhesive layer 14 For example, it may be a layer composed of a transparent resin obtained by curing a liquid curable resin compound. The curable resin compound may be, for example, a photocurable resin compound or a thermosetting resin compound and the like, with a photo-curable resin compound containing a curable compound and a photopolymerization initiator being preferred. As the curable resin compound, for example, a photo-curable resin compound for forming a layer-like portion as described in Patent Document 1 may preferably be given.

The adhesive layer 14 may further be associated, for example, with OCA, which is separately in the form of a film on the coverslip 12 , as mentioned above, is cured.

The thickness of the adhesive layer 14 For example, it may preferably range from 5 to 400 microns and more preferably from 50 to 200 microns. Furthermore, the storage shear module reaches the adhesive layer at a temperature of 25 ° C 14 for example, preferably from 5 kPa to 5 MPa, and more preferably from 1 MPa to 30 MPa.

Method for producing a cover glass attached via an adhesive layer

Now, a method for producing a cover glass attached via an adhesive layer will be described 10 described. Hereinafter, an embodiment will be described in which a liquid resin compound on a cover glass 12 is applied, whereupon hardening thereof takes place.

First, along the peripheral portion 12b of the cover glass 12 a light shielding section 20 formed in the form of a frame. Then it is on the entire first main surface 12c of the cover glass 12 a curable resin compound for the purpose of the light-shielding portion 20 using a method such as a press-coating (die-coater) or roll-coater applied to form a curable resin compound film (not shown in the figure). The curable resin compound film is cut as described later to form an adhesive layer 14 forms.

Then, a film material is bonded to the surface of the curable resin compound film (not shown). The film material is cut, as will be described later, to give a protective film 16 forms. After bonding the film material to the surface of the curable resin compound film, the curable resin compound film is cured by a photocuring treatment or a thermosetting treatment to give a laminate in which the curable resin compound film is protected from the film material.

Then, in the obtained laminate, a cutting line is set at a position facing a side surface 14b the adhesive layer 14 and the laminate is cut along the cutting line by means of a laser beam. This can be an attached via an adhesive layer cover glass 10 received, where a protective film 16 at the first main surface 14a the adhesive layer 14 is trained.

Here, in a case where a pre-cured adhesive layer film with the transparent surface material 10 or in a case where the resin compound can be applied precisely, the cutting step is also omitted.

On-board display device

Now an on-board display device 100 of the present embodiment.

2 is a schematic sectional view showing the on-board display device 100 , As in 2 is shown, the on-board display device 100 a concave housing 106 on. On a housing bottom element 107 which is a bottom plate of the housing 106 is is a background light unit 102 mounted, and on the backlight unit 102 is a display field 104 assembled. In this way, the backlight unit 102 and the display field 104 in the case 106 accommodated. The housing 106 has an opening section 108 , where the display field 104 on the opening 108 attached to your own page. The area of the display panel 104 according to the opening 108 is as a display interface 104a thought. This will be a display panel module 100a from the background light 102 and the display panel 104 , which are its main components, formed.

The background light unit 102 is composed of, for example, a lens sheet, a diffusion sheet, a photoconductive sheet, a lamp, a reflective plate, and the like, the thickest of which is usually the light guide plate, which is the constituent main element in determining the overall strength of the backlight unit. The thickness of the light guide plate is preferably at most 10 mm, more preferably at most 7 mm, and most preferably at most 5 mm. This is desirable to achieve a thin configuration of the housing through the narrow frame. The thickness of the light guide plate is preferably at least equal to 1 mm, more preferably at least equal to 2 mm, and most preferably at least equal to 4 mm. This is desirable to prevent breakage of the light guide plate by a bending load when a shock is applied to the portion of the backlight unit.

The Young's modulus of the material for forming the light guide plate is preferably at least equal to 1 GPa, more preferably at least equal to 2 GPa, most preferably at least equal to 3 GPa, and most preferably at least equal to 60 GPa. This is desirable to improve the impact resistance of the coverslip.

The linear expansion coefficient of the material for forming the light guide plate is preferably at most 800 × 10 ^-7 / ° C., more preferably at most 600 × 10 ^-7 / ° C., and most preferably at most 200 × 10 ^-7 / ° C. This is desirable to suppress the thermal expansion of the light guide plate by a light source in the backlight unit or by an increase in the internal temperature of the vehicle and to achieve a thin configuration of the housing through a narrow frame.

As the optical properties of the material for forming the light guide plate, it is preferable that the minimum value of the internal transmittance in a wavelength range of 400 to 700 nm is 80% and the difference between the maximum value and the minimum value is 50 mm in the condition of an optical path length of 50 mm internal transmittance is equal to or less than 15%. Even more preferable is when the aforementioned minimum value of the internal transmittance is at least 85% and the difference between the maximum value and the minimum value of the internal transmittance is at most 13%. It is further preferable that the aforementioned minimum value of the internal transmittance is at least 90% and the difference between the maximum value and the minimum value of the internal transmittance is at most 8%.

The material for forming the light guide plate is not particularly limited as long as it satisfies the conditions described above, in addition to the finished on-board display device 100 satisfies the formula (I) described below. Specifically, the material for forming the light guide plate is an acrylic resin, polycarbonate, glass and the like, of which glass is preferable. It has an excellent Young's modulus and is also excellent in achieving a high strength of the housing or the backlight unit, a small expansion due to heat and moisture, and a thin configuration of the housing. The glass may undergo a reinforcing treatment, wherein the reinforcing treatment is not limited to a chemical or physical treatment but is preferably a chemical reinforcement.

Furthermore, the end surface of the glass may preferably be tapered. In addition, it is preferred if the rejuvenation is followed by chemical reinforcement. This is desirable to prevent breakage of the end surface of the light guide plate due to vibration of the disc-internal display device.

Furthermore, subject to the structure of the display panel 104 and the material and the like for the housing 106 (Including the housing bottom element 107 ) no special limitation, as long as the on-board display device 100 satisfies the formula (I) described below. The outer shape and size of the housing bottom element 107 are in correspondence with the outer shape of the on-board display device 100 suitably determined. In an on-board display device 100 has recently been the display panel module 100a designed to be thinner for the purpose of design. The outer shape of the display panel 104 is usually rectangular, in which case the outer shape of the housing bottom element 107 is preferably rectangular. The given plan view size of the housing bottom element 107 is preferably selected such that when a boundary portion between the cover glass 12 and the display panel 104 as a stepped CG rear section 300 is referred to, the housing bottom element 107 is connected to the lower portion such that the entire stepped CG rear side portion 300 is covered vertically from the furthest rearward side when viewed. This is desirable for giving excellent impact resistance in a head butt test, which will be described later. The size of the housing bottom element 107 is preferably greater than or equal to that of the cover glass 12

In a case where the non-display area is wide from the display panel end to the cover glass end, it is preferable that the case bottom member 107 is connected to the lower portion such that the stepped CG rear side portion 300 is covered.

Further, for example, on the lower surface side of the bottom case member 107 laminated another plate element. Preferably, with respect to such a plate member, when viewed vertically from the most rearward side, connection with the lower portion becomes such that the entire stepped CG rear side portion 300 is covered. This is also desirable in order to provide excellent impact resistance in a head butt joint test, which will be described later. The size of the plate element is particularly preferably greater than or equal to that of the cover glass 12 ,

As in 2 is shown in the opening 108 of the housing 106 a step from the display surface 104a of the display field 104 to the end surface 106a of the housing 106 available.

In the case of the cover glass attached via an adhesive layer 10 becomes after peeling off the protective film 16 the adhesive layer 14 with the display interface 104a of the display field 104 connected so that the opening 108 of the housing 106 is filled. This makes it possible with the cover glass 12 the entire area of the display surface 104a the vehicle display device 100 to the end surface 106a of the housing 106 to cover. The cover glass 12 acts as a protection element for the display surface 104a the on-board display device 100 ,

Thus, the on-board display device of the present invention has such a structure that lamination exists as the first layer from this first layer to an n-th layer. In particular, the onboard display device 100 As described above, for example, a structure in which at least four layers, that is, the cover layer 12 (first layer), the display panel 104 (second layer), the backlight unit 102 (third layer) and the housing bottom element 107 (fourth layer) are laminated in this order. Further, the on-board display device may be constituted to have no backlight unit and a structure such that at least three layers, that is, the cover glass (first layer), the display panel (second layer), and the case bottom element (third layer), in this order , are laminated. For example, in a case where the display panel is an organic EL panel or a PDP panel, the apparatus has the aforementioned structure without the backlight unit.

Further, in practice, an adhesive layer is present between the coverslip (first layer) and the display panel (second layer). The handling of such an adhesive layer will be described below.

The on-board display device as described above has a structure in which the cover glass is regarded as a first layer element (that is, the first layer element is the surface layer of the display surface side), wherein one type or a plurality of types of elements from the next layer of the first Layer are successively laminated such that such a laminate structure is formed that the laminate is such that it has a structure in which the respective elements are assembled in this order one after the other and assembled successively in that order, the respective elements not for the purpose have to be connected to the lamination, but can be partially or completely laminated with a room or else may be partially enclosed or overlapped, resulting in laminated structures with various variations.

Meanwhile, in the on-board display device, the cover glass must have excellent impact resistance so that it does not break even if the head of an occupant or the like impacts at the time of a collision of the vehicle.

E₁

der Youngsche Modul des Deckglases (Einheit: GPa) ist,

t₁

die Dicke des Deckglases (Einheit: mm) ist,

E_n

der Youngsche Modul des Elementes der n-ten Schicht (Einheit: GPa) ist, und

t_n

die Dicke der n-ten Schicht (Einheit: mm) ist.

It has been found in the context of the present invention that the impact resistance of the coverslip is excellent when the on-board display device of the above structure satisfies the following formula (I): P ≦ 0.0302t ₁ ² + 0.0039t ₁ + 0.0478 Formula (I) wherein in the formula (I) P = P = E ₁ / (E ₁ t ₁ ² + ... + E _n t _n ² ),

E ₁

the Young's modulus of the cover glass (unit: GPa) is,

t ₁

the thickness of the cover glass (unit: mm) is

E _n

the Young's modulus of the nth layer element (unit: GPa) is, and

t _n

the thickness of the nth layer (unit: mm) is.

In the above formula, n denotes an integer of at least 2.

The impact resistance of the coverslip, which is excellent when formula (I) is satisfied, is shown under "Examples" which will be described later. That is, under "Examples", it is shown that in a case where formula (I) is not satisfied (in the comparative examples), the glass breaks, while in a case where the formula (I) is satisfied (at Examples), the coverslip does not break.

E₁:

Youngscher Modul des Deckglases (Einheit: GPa)

t₁:

Dicke des Deckglases (Einheit: mm)

E₂:

Youngscher Modul des Anzeigefeldes (Einheit: GPa)

t₂:

Dicke des Anzeigefeldes (Einheit: mm)

E₃:

Youngscher Modul der Hintergrundlichteinheit (Einheit: GPa)

t₃:

Dicke der Hintergrundlichteinheit (Einheit: mm)

E₄:

Youngscher Modul des Gehäusebodenelementes (Einheit: GPa)

t₄:

Dicke des Gehäusebodenelementes (Einheit: mm)

Further, the on-board display device as described above has, for example, a four-layered structure including the cover glass (first layer), the display panel (second layer), the backlight unit (third layer), and the case bottom element (fourth layer), with the above-described P as follows is expressed. P = E ₁ / (E ₁ t ₁ ² + E ₂ t ₂ ² + E ₃ t ₃ 2 + E ₄ t ₄ ² )

E ₁ :

Younger module of the cover glass (unit: GPa)

t ₁ :

Thickness of cover glass (unit: mm)

E ₂ :

Young's module of the display panel (unit: GPa)

t ₂ :

Thickness of the display panel (unit: mm)

E ₃ :

Young's module of the backlight unit (Unit: GPa)

t ₃ :

Thickness of the backlight unit (unit: mm)

E ₄ :

Young's module of the housing bottom element (unit: GPa)

t ₄ :

Thickness of the housing bottom element (unit: mm)

Here, the backlight unit has a structure in which a thick light guide plate made of a glass plate, a polycarbonate plate or an acrylic resin and a plurality of thin functional films such as a reflective polarizing film, a brightness-enhancing film and the like are laminated however, due to the light guide plate dominating the strength of the backlight unit, the calculation is made by using the Young's modulus of the light guide plate as the Young's modulus of the backlight unit.

The Young's modulus (E ₁ ) of the cover glass preferably ranges from 60 to 80 GPa, and more preferably from 70 to 80 GPa.

The Young's modulus (E ₂ ) of the display panel preferably ranges from 60 to 80 GPa, and more preferably from 70 to 80 GPa.

The Young's modulus (E ₃ ) of the backlight unit preferably ranges from 1 to 90 GPa, more preferably from 2 to 90 GPa, and most preferably from 60 to 90 GPa.

The Young's modulus (E ₄ ) of the housing bottom element preferably ranges from 40 to 250 GPa, more preferably from 150 to 250 GPa. Here, each of the display panel, the backlight unit, and the housing may be a composite material formed of a plurality of combined materials. In such a case, it is preferable that the Young's modulus of the entire composite material is in the aforementioned numerical range.

The Young's modulus of each element is measured by the tensile test (JIS K7161, JIS K7113).

The thickness (t ₁ ) of the cover glass ranges from 0.5 to 2.5 mm, preferably from 0.7 to 2 mm and most preferably from 1.3 to 2 mm.

The thickness (t ₂ ) of the display panel preferably ranges from 1 to 2 mm, and more preferably from 1.1 to 1.3 mm.

The thickness (t ₃ ) of the backlight unit preferably ranges from 1 to 10 mm, more preferably from 2 to 6 mm, and most preferably from 3 to 5 mm.

The thickness (t ₄ ) of the housing bottom element preferably ranges from 0.5 to 4 mm and particularly preferably from 1 to 4 mm.

The thickness of each element is the length in the vertical direction according to 2 ,

Here, in the internal display device as described above, at least one layer of the layers from the cover glass (first layer) to the n-th layer is an adhesive layer. For example, in the above-described four-layer structure, between the cover glass 12 (first layer) and the display panel 104 (second layer) an adhesive layer 14 (referred to as 1.5-th layer) arranged.

If the Young's modulus (E _1.5 ) and the thickness (t _1.5 ) of the adhesive layer are taken into account, the said P can be expressed as follows: P = E ₁ / (E ₁ t ₁ ² + E _1.5 t _1.5 ² + E ₂ t ₂ ² + E ₃ t ₃ ² + E ₄ t ₄ ² )

However, the Young's modulus (E _1.5 ) of the adhesive layer is sufficiently small as compared with the Young's modulus of the other layers, the thickness (t _1.5 ) of which ranges, for example, from 5 to 400 μm. Thus, the value of "E _1.5 t _1.5 ² " at the aforementioned P is negligibly small compared to the values of the other "E ₁ t ₁ ² " to "E ₄ t ₄ ² ".

Even if the adhesive layer is present in the laminated structure (first layer to n-th layer), therefore, in the present embodiment, considering formula (I), the adhesive layer is considered not to exist. In other words, the value P can be obtained on the assumption that the value of "E _1.5 t _1.5 ² " is 0 (zero).

Hereinafter, P in formula (I) will be described.

• Krümmung

In a case where beams (composite beams) of different materials layered parallel to the neutral axis of the bend undergo bending with respect to the curvature (equal in each layer) and the stress formed in each layer, the formulas (1) to (3), which are theoretical calculation formulas (A _i : cross-sectional area of the ith layer, E _i : Young's modulus of the ith layer, I _i : second cross-sectional moment of the ith layer, are considered n: number of layers). • Position of the neutral axis

• curvature

Now a four-layered structure, as in 3 is shown, this can be described by the following formulas (4) to (6) (M: bending moment, y ': position of the neutral axis, y: distance from the neutral axis). σ ₁ = E ₁ {My / (E ₁ I ₁ + E ₂ I ₂ + E ₃ I ₃ + E ₄ I ₄ )} σ ₂ = E ₂ {My / (E ₁ I ₁ + E ₂ I ₂ + E ₃ I ₃ + E ₄ I ₄ )} σ ₃ = E ₃ {My / (E ₁ I ₁ + E ₂ I ₂ + E ₃ I ₃ + E ₄ I ₄ )} σ ₄ = E ₄ {My / (E ₁ I ₁ + E ₂ I ₂ + E ₃ I ₃ + E ₄ I ₄ )} (4) y '= {bE ₁ h ₁ (h _1/2) + bE ₂ h ₂ (h ₁ + h _2/2) + bE ₃ h ₃ (h ₁ + h ₂ + h _3/2) + bE ₄ h ₄ (h ₁ + h ₂ + h ₃ + h _4/2)} / (bE ₁ h ₁ + h ₂ + bE ₂ bE ₃ h ₃ + h ₄ bE ₄₎ (5) I ₁ = bh ₁ ^3/12 + bh ₁ (y '- h _1/2) ² I ₂ = bh ₂ ^3/12 + bh ₂ (- y h ₁ + h _2/2' ² I ₃ = bh ₃₎ ^3/12 + bh ₃ (h ₁ + h ₂ + h _3/2 - y ') ² I ₄ = bh ₄ ^3/12 + bh ₄ (h ₁ + h ₂ + h ₃ + h _4/2 - y' ² (6)

If the four-layered structure of cover glass / display panel / background light unit / housing bottom element is considered here, the load which forms in the rear surface of the cover glass as a first layer should be as small as possible so that the cover glass does not break. In other words, σ ₁ in the formula (4) should be better small, and it should be understood that σ ₁ becomes small when the Young's modulus of each element constituting each layer is larger and the layer is thicker.

From formula (6) it can be seen that the second cross-sectional moment has a correlation with the cube of the thickness of the cover glass, while it can be seen from formula (4) that the back surface position (y) of the first layer, ie the thickness, is multiplied. therefore, as a parameter for judging whether the cover glass breaks, the value P is represented by the following formula derived from formulas (4) and (6). P = E ₁ / (E ₁ t ₁ ² + E ₂ t ₂ ² + E ₃ t ₃ ² + E ₄ t ₄ ² )

The display panel may be, for example, a liquid crystal panel, an organic EL panel, a PDP, an electronic ink type panel, and the like, and may have a touch panel and the like.

In the case of a display panel that is not the liquid crystal panel, such as in the case of an organic EL panel or a POP, the calculation is performed on a layout that does not include the backlight unit.

Such an on-board display device may be, for example, an on-instrument type car navigation device mounted on an instrument panel, a car navigational type vehicle navigation device embedded in the dashboard of the vehicle, and the like, and may also include an apparatus. which is not a navigation device (for example, an instrument panel).

Examples

Hereinafter, embodiments of the present invention will be described specifically by way of examples and the like. However, the present invention is not limited to these examples.

Preparation of the cover glass

As a cover glass, a reinforced glass was treated with an aluminosilicate glass which has undergone chemical strengthening treatment (trade name "Dragon Trail" (Registered Trade Mark) manufactured by Asahi Glass Co., Ltd. Compression stress layer depth: 38 μm, Compression stress layer surface compression load: 774 MPa).

Preparation of the cover glass attached via an adhesive layer

On the first major surface of the coverslip, an OCA film ("MHM-FWD", manufactured by Nichiei Kakoh Co., Ltd.) was laminated to prepare a coverslip attached via an adhesive layer.

Preparation of the test specimen

First, a test specimen was 200 prepared to perform a rigid body model impact test (hereinafter called "head impact test"). The test sample 200 will be explained below 4 to 6 described.

4 is a perspective view illustrating the sample. 5 is a cross-sectional view along a line AA in 4 , 6 is a plan view to show the sample.

It is assumed that the test piece is an on-board display device 100 of the am dashboard type is.

The on-board display device 100 has a housing bottom element 107 , wherein on the circumference of the housing bottom element 107 four case frames 109 are arranged, each having a rib inside. From the housing bottom element 107 and the four case frames 109 becomes a housing 106 formed with a rectangular recess on the central surface, wherein in this recess a display panel module 100a which is a background light unit 102 and a display field 104 as constituent main elements.

An end portion of the upper surface to own side of the backlight unit 102 is with an end portion on the lower surface to own side of the display panel 104 for example, by a double-sided tape or tape (days) 207 appropriate. This is between the display field 104 and the backlight unit 102 an air gap by virtue of the thickness of the double-sided tape or adhesive tape 207 available. The space formed by this air gap is from 0.5 to 1.5 mm from the backlight unit 102 selected to the display field. In this case, the air gap is generally selected at 1.5 mm, although this may not be equal to 1.5 mm, depending on the circumstances, and possibly even no air gap is present. The air gap is determined by the thickness of an adhesive element, such as the double-sided tape 207 , controlled or regulated, wherein, however, such an adhesive element, depending on the situation may not be used. The upper surface of the display panel 104 is at a lower position compared to the upper surface of the housing frame 109 with circumferential attachment and has a recess. To fill the recess, the adhesive layer becomes 14 of the cover glass attached via an adhesive layer 10 on the upper surface of the display panel 104 connected. The border of the cover glass 12 and the display panel 104 becomes the stepped CG rear portion 300 , A housing end frame 110 is outside the side end surface of the cover glass 12 and on the upper surface of the housing frame 109 arranged.

Such an on-board display device 100 is on a tight fixation rib 213 that with a support plate 215 is integral, which in turn is a flat plate, by a bolt 211 fixed in a room in a rack 109 is arranged.

Further, in the present on-board display device, it is preferable that the case bottom member 107 to join at the lower portion to the entire stepped CG rear portion 300 to cover vertically from the furthest rearward side when viewed. Furthermore, as in 5 is shown when the distance from the stepped CG rear portion 300 to the outer periphery of the on-board display device 100 is chosen as L ₂ and L ₁ is chosen equal to L _2/2 , preferred that as the housing bottom element 107 one having an end with a size at least L ₁ greater than the cross-sectional size of the display panel 104 , please refer 5 (a) , is (that is one side of the Housing base element 107 is at least 2L ₁ greater than one side of the display panel 104 ) is used around the stepped CG rear section 300 to cover. This is because the effect of reducing the tensile load in the stepped CG rear-end section 300 expected to occur in the head impact test. It is also more preferable that the entire stepped CG rear portion 300 by covering an end having a size larger by at least L ₁ and at most L ₂ than the cross-sectional size of the display panel 104 is. In addition, it is more preferable if, as in 5 (b) is shown, one having an end having a size larger by L ₂ than the cross-sectional size of the display panel is used 104 is (that is, equal to the size given in plan view when the on-board display device 100 from the vertical direction) to the entire stepped CG rear portion 300 to cover. This is because the effect of reducing the tensile load in the stepped CG rear-end section 300 is to be expected the most in the head impact test.

Further, also in the present on-board display device, on the stepped CG rear side section 300 the housing bottom element 107 connected to the lower portion, wherein it is preferred that provided with a rib rib structure at several points for the housing frame 109 to use to increase the strength. This is because of the case frame 109 For the purpose of designing the display panel, a resin material is often used. However, there may be a case where the strength due to the resin is poor, and in such a case, by employing the above-described rib structure, it becomes possible to obtain excellent impact resistance in the head impact test. Here, the housing 106 be a structure where the case frame 109 , the housing bottom element 107 and the housing end frame 110 are each separate or form a molded product in which everything is integrated, or optionally, there is a structure in which a partial integration is given, and therefore, the structure is not particularly limited.

In the thus prepared test specimen 200 The cover glass was used by every ex 12 , the display panel 104 , the backlight unit 102 and the housing bottom element 107 changed so that the Young's modulus and the thickness were varied as shown in Tables 1 and 2 below.

Furthermore, the test specimen was used 200 Lime-soda-glass as replacement for the display panel 104 was used, and it was a polycarbonate plate as a substitute for the backlight 102 used.

Furthermore, as a housing bottom element 107 an aluminum plate (Young's modulus: 68.6 GPa) or an iron plate (Young's modulus: 206 GPa).

In the case of a display panel of the aforementioned ordinary TFT liquid crystal panel, its structure is basically a polarizing plate / glass substrate (having a plate thickness of, for example, 0.55 mm) / liquid crystal layer / glass substrate (having a plate thickness of, for example, 0.55 mm) / polarizing plate However, since the strength of the polarizing plates and the liquid crystal layer is low, the glass plates of the liquid crystal panel dominate the strength. Accordingly, the calculation was made by replacing the Young's modulus of the glass substrates forming the liquid crystal panel.

Furthermore, those with H ₁ to H ₃ and W ₁ to W ₃ in 6 designated sizes: H ₁ : 120 mm, H ₂ : 150 mm, H ₃ : 250 mm, W ₁ : 173 mm, W ₂ : 250 mm, W ₃ : 350 mm. The size of the housing bottom element 107 was 160 × 260 mm, which is larger than the display panel 104 is.

• • Klebeschicht 14: Dicke: 175 μm, vertikal: 120 mm, horizontal: 173 mm, Ablageschermodul: 8 kPa.
• • doppelseitiges Band bzw. Klebeband 207: „Scotch PBT-10”, hergestellt von Sumitomo 3M Ltd., Bandbreite: 5 mm, Banddicke: 0,5 mm
• • Gehäuserahmen 109: Material: ABS, Dicke: 1 mm
• • Gehäuseendrahmen 110: Material: ABS, Dicke 2 mm, Breite: 5 mm
• • Bolzen: 211: Material: Eisen
• • Fixierrippe 213: Material: Eisen, Größe 19 mm × 100 mm × 50 mm
• • Stützplatte 215: Material: Eisen, Lagendicke: 9 mm, vertikal: 250 mm, horizontal: 350 mm

Furthermore, the test specimen was 200 the other parts are as follows:

• • adhesive layer 14 : Thickness: 175 μm, Vertical: 120 mm, Horizontal: 173 mm, Storage modulus: 8 kPa.
• • double-sided tape or adhesive tape 207 : "Scotch PBT-10" manufactured by Sumitomo 3M Ltd., tape width: 5 mm, tape thickness: 0.5 mm
• • Body frame 109 : Material: ABS, thickness: 1 mm
• • Housing end frame 110 : Material: ABS, thickness 2 mm, width: 5 mm
• • Bolt: 211 : Material: iron
• • Fixing rib 213 : Material: iron, size 19 mm × 100 mm × 50 mm
• • support plate 215 : Material: iron, layer thickness: 9 mm, vertical: 250 mm, horizontal: 350 mm

Evaluation of impact resistance (head impact test)

Then the support plate 215 of the sample 200 placed on a horizontal plane, between the on-board display device 100 and the support plate 215 a shock absorbing pad ("CF45" manufactured by KCC Shokai Limited, thickness: 25.4 mm) was sandwiched in two stages, and at the impact position P (see 6 ) on the second main surface 12d of the cover glass 12 dropped an unillustrated model of a spherical rigid body (material: iron, diameter: 165 mm, mass: 19.6 kg) from a height of 794 mm so that it impinges at an impact speed of 3.9 m / s and so on Had energy of 152.5 J at the time of the impact.

With regard to this test method, reference is made to: "Exhibit 28" Technical standards for shock absorption instrument panel "from" Article 20: Riding equipment "of" Safety standards for road transport vehicles "(hereinafter simply referred to as" Standards ") Ministry of Land, Infrastructure and Transport. According to these "standards", the model of a spherical rigid body (material: iron, diameter: 165 mm, weight: 6.8 kg) is released and bounced at an impact speed of 6.7 m / s, so that the energy equals the moment of impact 152.4 yrs was.

This means that in the head impact test using the test specimen 200 , the energy at the time of the impact was adjusted so that it was the same as the "standards".

The collision position P (see 6 ) on the coverslip 12 on which the model of the rigid body impinged was chosen such that it faces a side opposite to that of the fixing rib 213 to your own side from the center of the display panel modules 100a when looking at the sample 200 from the upper surface. In particular, the impact position P was chosen such that it would not be on the housing frame 109 but on the display panel 104 and at a position 10 mm inside the end of the display panel 104 was located.

Tabelle 2

The results of the impact of the model of the rigid body are in the in 7 laid down graph. A case where the cover glass is not broken is indicated by "o", while a case where the cover glass is broken is indicated by "×". Here, "o" can be understood as an indication of excellent impact resistance, that is, lack of breakability, even when the head of the occupant or the like impacts at the time of an impact accident. The results are shown in Tables 1 and 2. Table 1

Table 2

As in the in 7 it can be seen that in the case where formula (I) is not satisfied (comparative examples), the cover glass is broken, whereas in the case where formula (I) is satisfied (examples), the cover glass does not break.

Industrial Applicability

According to the present invention, it is possible to obtain an onboard display device with excellent impact resistance of the cover glass, which is useful in an on-board display device for mounting on a vehicle such as a motor vehicle.

The entire revelation of submitted on 22 August 2014 Japanese Patent Application No. 2014-169322 including the description, the claims, the drawing and the abstract are hereby incorporated by reference in their entirety.

LIST OF REFERENCE NUMBERS

10

Cover glass applied over an adhesive layer

12

cover glass

12a

available space

12b

scope

12c

first main surface of the cover glass

12d

second main surface of the cover glass

14

adhesive layer

14a

first major surface of the adhesive layer

14b

Side surface of the adhesive layer

16

protective film

16a

first main surface of the protective film

20

Light shield section

100

on-board display device

100a

Display module

102

Backlight unit

104

display

104a

display surface

106

casing

106a

End surface of the housing

107

Housing base element

108

opening

109

housing frame

110

Gehäuseendrahmen

200

Test specimen

207

double-sided tape

211

bolt

213

fixing rib

215

support plate

300

stepped CG rear section

P

impact section

Claims (7)

An on-board display device formed by laminating elements of a surface layer cover glass as a first layer to an n-th layer, wherein: the cover glass is a reinforced glass having a plate thickness of 0.5 to 2.5 mm and a depth of a surface compression stress layer of at least 10 μm, and the on-board display device satisfies the following formula (I): P <= 0.0302t ₁ ² + 0.0039t ₁ + 0.0478 Formula (I) wherein in the formula (I) P = E ₁ / (E ₁ t ₁ ² + ... + E _n t _n ² ), E _{1 is} the Young's modulus of the cover glass (unit: GPa), t _{1 is} the thickness of the cover glass (unit: mm), E _{n is} the Young's modulus of the n-th layer element (unit: GPa), and t _{n is} the thickness nth layer (unit: mm), where n is an integer of at least 2. An on-board display device according to claim 1, wherein the elements from the cover glass to the n-th layer include a display panel and a case bottom member, and the size of the case bottom member is larger than the display portion of the display panel. An on-board display device according to claim 1 or 2, wherein the elements from the cover glass to the n-th layer include a backlight unit, the backlight unit has a light guide plate, and the light guide plate is made of glass. An on-board display device according to any one of claims 1 to 3, wherein the elements from the cover glass to the n-th layer include a display panel, a backlight unit, and a case bottom member, the backlight unit is mounted to the case bottom member, and the display panel is mounted to the backlight unit. An on-board display device according to any one of claims 1 to 4, wherein at least one layer of the elements from the cover glass to the n-th layer is an adhesive layer and the thickness of the adhesive layer ranges from 5 to 400 μm. An on-board display device according to any one of claims 1 to 5, wherein the surface compression load of the coverslip is at least 650 MPa. An on-board display device according to any one of claims 1 to 6, wherein the cover glass is a chemically strengthened glass having a plate thickness of 0.5 to 2.5 mm, a depth of a surface compression stress layer of at least 10 μm, and a surface compression stress of at least 650 MPa.

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