JP2006285022A - Transparent plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transparent plate to be used for a display device such as a HUD (head-up display) for cars, ships or others to display information in a front view field, the display eliminating a double image and having uniform and high display quality without display irregularity. <P>SOLUTION: The transparent plate is used for a display device which reflects display light from a display light source for imaging by the display light in the front view field of an observer and makes the observer visually recognize the image. The transparent plate comprises at least one transparent material and an optical retardation film, wherein the optical retardation film has ≥180°C glass transition temperature and ≤60 μm thickness. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a transparent plate, and more particularly to a transparent plate useful for a display device such as a head-up display (hereinafter, HUD).

  In recent years, for vehicles, ships, aircraft, etc., safety and convenience have been improved by HUD that displays information in the forward visual field. The HUD projects the display light of the display onto a transparent plate, reflects the display light on the surface of the transparent plate, the surface of the transparent plate, or a reflective film provided inside, and displays the display light in the front field of view. The image is visually recognized. The transparent plate is composed of a single plate or laminated glass or plastic, but there is a drawback that reflection at the interface with a large difference in interlayer refractive index, for example, reflection on the back surface of the transparent plate and the air interface is unavoidable, and the image is viewed twice. It was.

In order to eliminate this drawback, it has been proposed to provide a retardation film having a retardation corresponding to λ / 2 on a transparent plate.
However, when the retardation film is provided, the retardation film can be bonded to the transparent body and / or the intermediate film or directly to the intermediate film via an adhesive or pressure-sensitive adhesive, but it can withstand the bonding temperature condition at the time of bonding. The specific material of the retardation film is not disclosed, and defects and unevenness occur in the retardation film provided on the transparent plate, so that a double image can be partially seen when displaying finely. was there.

Japanese Patent Laid-Open No. 2-141720 Japanese Patent Laid-Open No. 10-96874

  The present invention provides a transparent plate for use in a display device such as a HUD that displays information in a front field of view for a vehicle, a ship, an aircraft, or other devices with uniform display quality with no display unevenness that makes a double image invisible. The purpose is to provide.

  In order to solve the above-mentioned problems, the present inventors considered that the glass transition temperature and thickness of the retardation film used inside or on the surface of the transparent plate are important, and as a result of intensive studies, We have succeeded in obtaining a display device such as a HUD for displaying information in a vehicle, ship, aircraft, or other front view with high display quality that makes it difficult to see the image.

That is, the present invention can be achieved by the following [1] to [8].
[1] A transparent plate for use in a display device that reflects display light from a display light source to form an image of the display light in the front field of view of the observer so that the observer can visually recognize the transparent light. The plate comprises at least one transparent body and a retardation film, and the retardation film has a glass transition temperature of 180 ° C. or more and a thickness of 60 μm or less.

[2] The transparent plate as described above, wherein the retardation film has a dimensional change rate of 0.5% or less when treated at 140 ° C. for 1 hour.

[3] The transparent plate as described above, wherein the retardation film is made of a polycarbonate resin.

[4] The transparent plate as described above, wherein the polycarbonate resin has a fluorene skeleton.

（上記式（Ａ）においてＲ_１〜Ｒ_８はそれぞれ独立に水素原子、ハロゲン原子および炭素数１〜６の炭化水素基から選ばれる少なくとも一種の基であり、Ｘは下記式（Ｘ） [5] The polycarbonate resin is represented by the following formula (A)

(In the above formula (A), R _{1 to} R ₈ are each independently at least one group selected from a hydrogen atom, a halogen atom and a hydrocarbon group having 1 to 6 carbon atoms, and X is the following formula (X):

であり、Ｒ_９およびＲ_１０はそれぞれ独立して水素原子、ハロゲン原子または炭素数１〜３のアルキル基である。）
で示される繰り返し単位および下記式（Ｂ）

R ₉ and R ₁₀ are each independently a hydrogen atom, a halogen atom or an alkyl group having 1 to 3 carbon atoms. )
And a repeating unit represented by the following formula (B)

（上記式（Ｂ）においてＲ_１１〜Ｒ_１８はそれぞれ独立に水素原子、ハロゲン原子および炭素数１〜２２の炭化水素基から選ばれる少なくとも一種の基であり、Ｙは下記式群（Ｙ）

(In the above formula (B), R _{11 to} R ₁₈ are each independently at least one group selected from a hydrogen atom, a halogen atom and a hydrocarbon group having 1 to 22 carbon atoms, and Y represents the following formula group (Y):

であり、ここでＲ_１９〜Ｒ_２１、Ｒ_２３及びＲ_２４はそれぞれ独立に水素原子、ハロゲン原子及び炭素数１〜２２の炭化水素基から選ばれる少なくとも１種の基であり、Ｒ_２２及びＲ_２５はそれぞれ独立に炭素数１〜２０の炭化水素基から選ばれる少なくとも１種の基であり、Ａｒ_１〜Ａｒ_３はそれぞれ独立に炭素数６〜１０のアリール基から選ばれる少なくとも１種の基である。）
で示される繰り返し単位を含んでなり、上記式（Ａ）で表される繰り返し単位が当該ポリカーボネートを構成する繰り返し単位の合計を基準として全体の１０〜９０ｍｏｌ％を占めるポリカーボネート共重合体および／またはブレンド体である上記の透明板。

Here, R _{19 to} R ₂₁ , R ₂₃ and R ₂₄ are each independently at least one group selected from a hydrogen atom, a halogen atom and a hydrocarbon group having 1 to 22 carbon atoms, and R ₂₂ and R ₂₅ is at least one group independently selected from a hydrocarbon group having 1 to 20 carbon atoms, and Ar _{1 to} Ar ₃ are each independently at least one group selected from an aryl group having 6 to 10 carbon atoms. It is. )
A polycarbonate copolymer and / or blend comprising the repeating unit represented by formula (A), wherein the repeating unit represented by the formula (A) accounts for 10 to 90 mol% of the total of the repeating units constituting the polycarbonate. Said transparent board which is a body.

（上記式（Ｃ）においてＲ_２６〜Ｒ_２７はそれぞれ独立に水素原子およびメチル基から選ばれる。）で示される繰り返し単位が全体の１０〜９０ｍｏｌ％と、下記式（Ｄ） [6] The polycarbonate resin is represented by the following formula (C)

(In the formula (C), R _{26 to} R ₂₇ are each independently selected from a hydrogen atom and a methyl group.) The repeating unit represented by 10 to 90 mol% of the whole is represented by the following formula (D)

（上記式（Ｄ）においてＲ_２８〜Ｒ_２９はそれぞれ独立に水素原子およびメチル基から選ばれる。）
で示される繰り返し単位が当該ポリカーボネートを構成する繰り返し単位の合計を基準として全体の９０〜１０ｍｏｌ％を占めるポリカーボネート共重合体および／またはブレンド体である上記の透明板。

(In the formula (D), R _{28 to} R ₂₉ are each independently selected from a hydrogen atom and a methyl group.)
The transparent plate as described above, wherein the repeating unit represented by (1) is a polycarbonate copolymer and / or blend occupying 90 to 10 mol% of the total of the repeating units constituting the polycarbonate.

[7] The transparent plate, wherein the retardation film is located between two transparent bodies.

[8] A display device comprising at least the above-mentioned transparent plate and a display light source, wherein the display light from the display light source is reflected on the transparent plate so as to be within the observer's front field of view. A display device that forms an image of display light so that the observer can visually recognize the display light.

  According to the present invention, since a retardation film having high heat resistance and good dimensional stability is used, it is difficult for a double image to be seen. It is possible to obtain a display device such as a HUD that displays information therein.

  The retardation film used in the present invention can be bonded to a transparent body and / or an intermediate film via an adhesive or a pressure-sensitive adhesive, or directly to an intermediate film. For example, polyvinyl butyral (hereinafter PVB), which is a typical intermediate film, is used. In general, pressure bonding is performed under a temperature condition of about 140 ° C. In order to maintain a uniform retardation even under such temperature conditions, the glass transition temperature of the retardation film is 180 ° C. or higher, preferably 180 to 280 ° C., more preferably 185 to 260 ° C., more preferably 190 to 190 ° C. It is good that it is 250 degreeC, Most preferably, it is 195-240 degreeC. When the temperature is less than 180 ° C., the dimensional stability is poor, and when the temperature exceeds 280 ° C., the temperature control in the stretching process becomes very difficult, so that the production becomes difficult.

  The dimensional change rate of the retardation film at 140 ° C. for 1 hour is preferably 0.5% or less, more preferably 0.4% or less, still more preferably 0.3% or less, and particularly preferably 0.2%. Hereinafter, it is most preferable that it is 0.1% or less. If the dimensional change rate is larger than 0.5%, stress may be generated between the layers by heat treatment, and phase difference unevenness, bubbles, haze, and the like may occur. A retardation film having such characteristics can be obtained, for example, by forming a thermoplastic polymer having a relatively high glass transition temperature into a film and stretching it.

  The thickness of the retardation film is 60 μm or less, preferably 1 to 60 μm, more preferably 5 to 50 μm, still more preferably 10 to 45 μm, still more preferably 15 to 40 μm, and still more preferably 20 to 30 μm. If the thickness exceeds 60 μm, phase difference unevenness occurs in the phase difference film at the time of adhesion, or when filling the area where the phase difference film is not disposed with another material, a large amount of material is required, or the total thickness of the transparent plate is The problem of becoming thick arises. Moreover, handling of a film will become difficult as it is 1 micrometer or less.

The in-plane retardation value (R value) of the retardation film used in the present invention is represented by the following formula (a).
_{R = (n x -n y)} × d (a)
It is represented by In the above formulas, n _x, n _y is the three-dimensional refractive index of the retardation film, the x-axis direction refractive index is a maximum in each film plane, the refractive in the y-axis direction perpendicular to the x-axis in the film plane Rate. D is the thickness (nm) of the retardation film.

  The in-plane retardation of the retardation film used in the present invention is preferably λ / 2 over a wide wavelength range, and particularly preferably around 275 nm, which is λ / 2 at a wavelength of 550 nm with high visibility. Specifically, it is 200-350 nm, More preferably, it is 250-300 nm. The retardation value and the bonding angle with the transparent plate are appropriately adjusted.

  In the present invention, the optical anisotropy of the retardation film is regarded as a refractive index ellipsoid, and this three-dimensional refractive index is obtained by a method for obtaining it by a known refractive index ellipsoid formula. Since this three-dimensional refractive index is dependent on the wavelength of the light source used, it is preferably defined by the light source wavelength used. In the display device of the present invention, the center wavelength of the display body is discussed. If not specified, the value at 550 nm is used.

  The material constituting the retardation film is not particularly limited, and has excellent heat resistance, good optical performance, and can be formed into a film, such as polyarylate, polyester, polycarbonate, polyolefin, polyether, polysulfine-based copolymer, A thermoplastic polymer such as polysulfone or polyethersulfone is preferred.

  The thermoplastic polymer may be a blend of two or more types of copolymers, or may be a blend of one or more types of copolymers and the above-mentioned blend or other polymers, or two or more types of copolymers. It may be a blend or copolymer or a blend of other polymers. A polycarbonate copolymer produced by reacting a bisphenol with a carbonate ester-forming compound such as phosgene or diphenyl carbonate is excellent in transparency, heat resistance and productivity, and can be particularly preferably used. The polycarbonate copolymer is preferably a copolymer having a structure having a fluorene skeleton.

で示される繰り返し単位および下記式（Ｂ）

で示される繰り返し単位からなり、かつ上記式（Ａ）で表される繰り返し単位が全体（上記式（Ａ）で表される繰り返し単位と上記式（Ｂ）で表される繰り返し単位の合計を基準として）の１０〜９０ｍｏｌ％を占めるポリカーボネートである。該ポリカーボネートは、共重合体、２種類以上のポリマー（共重合体を含む）のブレンド体、またはこれらの混合物である。 Specifically, the following formula (A)

And a repeating unit represented by the following formula (B)

The repeating unit represented by the above formula (A) is the whole (based on the total of the repeating unit represented by the above formula (A) and the repeating unit represented by the above formula (B). As a polycarbonate). The polycarbonate is a copolymer, a blend of two or more kinds of polymers (including a copolymer), or a mixture thereof.

In the above formula (A), R _{1 to} R ₈ are each independently selected from a hydrogen atom, a halogen atom, and a hydrocarbon group having 1 to 6 carbon atoms. Examples of the hydrocarbon group having 1 to 6 carbon atoms include alkyl groups such as methyl group, ethyl group, isopropyl group, and cyclohexyl group, and aryl groups such as phenyl group. Among these, a hydrogen atom and a methyl group are preferable.

で表されるフルオレン環であり、Ｒ_９およびＲ_１０はそれぞれ独立して水素原子、ハロゲン原子または炭素数１〜３のアルキル基である。 X is the following formula (X)

And R ₉ and R ₁₀ are each independently a hydrogen atom, a halogen atom or an alkyl group having 1 to 3 carbon atoms.

In the formula (B), R _{11 to} R ₁₈ are each independently selected from a hydrogen atom, a halogen atom, and a hydrocarbon group having 1 to 22 carbon atoms. Examples of the hydrocarbon group having 1 to 22 carbon atoms include alkyl groups having 1 to 9 carbon atoms such as a methyl group, an ethyl group, an isopropyl group, and a cyclohexyl group, and aryl groups such as a phenyl group, a biphenyl group, and a terphenyl group. It is done. Among these, a hydrogen atom and a methyl group are preferable.

からなる群より選ばれる少なくとも1種の基であり、Ｒ_１９〜Ｒ_２１、Ｒ_２３及びＲ_２４はそれぞれ独立に水素原子、ハロゲン原子及び炭素数１〜２２の炭化水素基から選ばれる少なくとも１種の基である。かかる炭化水素基については、上記したものと同じものを挙げることができる。Ｒ_２２及びＲ_２５はそれぞれ独立に炭素数１〜２０の炭化水素基から選ばれ、かかる炭化水素基については、上記したものと同じものを挙げることができる。Ａｒ_１〜Ａｒ_３としてはフェニル基、ナフチル基等の炭素数６〜１０のアリール基を挙げられる。 Y is the following formula group

At least one group selected from the group consisting of R _{19 to} R ₂₁ , R ₂₃ and R ₂₄ each independently at least one selected from a hydrogen atom, a halogen atom and a hydrocarbon group having 1 to 22 carbon atoms. It is the basis of. Examples of the hydrocarbon group include the same ones as described above. R ₂₂ and R ₂₅ are each independently selected from hydrocarbon groups having 1 to 20 carbon atoms, and examples of such hydrocarbon groups include the same ones as described above. Examples of Ar _{1 to} Ar ₃ include aryl groups having 6 to 10 carbon atoms such as a phenyl group and a naphthyl group.

で示される繰り返し単位と、下記式（Ｄ）

で示される繰り返し単位からなり、上記式（Ｃ）で表される繰り返し単位が全体（上記式（Ｃ）で表される繰り返し単位と上記式（Ｄ）で表される繰り返し単位の合計を基準として）の１０〜９０ｍｏｌ％を占めるフルオレン骨格を有するポリカーボネート共重合体および／またはブレンド体が特に好適である。 Among the above polycarbonates, the following formula (C) is used in terms of the balance of film forming properties, transparency, heat resistance, durability, productivity, and the like.

A repeating unit represented by the following formula (D):

The repeating unit represented by the above formula (C) is the whole (based on the total of the repeating unit represented by the above formula (C) and the repeating unit represented by the above formula (D). A polycarbonate copolymer and / or a blend having a fluorene skeleton occupying 10 to 90 mol% of the above is particularly suitable.

  More preferably, the repeating unit represented by the above formula (C) is 90 to 10 mol in total (based on the total amount of the repeating unit represented by the above formula (C) and the repeating unit represented by the above formula (D)). % Of a polycarbonate copolymer, a blend, and a mixture thereof.

In the above formula (C), R _{26 to} R ₂₇ are each independently a hydrogen atom or a methyl group, and preferably both are methyl groups from the viewpoint of handleability.

In the above formula (D), R _{28 to} R ₂₉ are each independently a hydrogen atom or a methyl group, and both are preferably a hydrogen atom from the viewpoint of economy and film characteristics.

  The copolymer may be a combination of two or more repeating units represented by the above formulas (A) and (B). In the case of a blend, two or more of the repeating units may be combined.

  Here, the molar ratio can be obtained for the entire polycarbonate bulk constituting the polymer oriented film, for example, by a nuclear magnetic resonance (NMR) apparatus, regardless of the copolymer or blend.

  The above copolymer and / or blend can be produced by a known method. As the polycarbonate, a method by polycondensation of a dihydroxy compound and phosgene, a melt polycondensation method or the like is preferably used. In the case of a blend, a compatible blend is preferable, but even if it is not completely compatible, light scattering between components can be suppressed and transparency can be improved by adjusting the refractive index between components.

  Retardation film used in the present invention The film is stretched on a polymer film such as the above polycarbonate to align the polymer chain. As a method for producing such a polymer film, a known melt extrusion method, solution casting method or the like is used. As the solvent in the solution casting method, methylene chloride, dioxolane and the like are preferably used in the case of polycarbonate.

  In the present invention, as described above, a polymer film produced by a melt extrusion method or a solution casting method is heated and stretched at a temperature near the glass transition temperature. In the film, for the purpose of improving stretchability, phthalates such as dimethyl phthalate, diethyl phthalate and dibutyl phthalate which are known plasticizers, phosphate esters such as tributyl phosphate, aliphatic dibasic esters, glycerin derivatives, A glycol derivative or the like may be contained. At the time of stretching, the organic solvent used at the time of film formation described above may remain in the film for stretching.

  The additives such as the plasticizer and the liquid crystal can change the wavelength dependency of the retardation of the retardation film, but the addition amount is preferably 10 wt% or less, more preferably 3 wt% or less with respect to the polymer solid content.

  In addition, UV absorbers such as phenyl salicylic acid, 2-hydroxybenzophenone, triphenyl phosphate, bluing agents for changing the color, antioxidants, heat stabilizers, antioxidants, light stabilizers, transparent nucleating agents In addition, polymer modifiers such as permanent antistatic agents and fluorescent brighteners may be present in the film at the same time.

  The retardation film of the present invention has good transparency, preferably a haze of 5% or less and a total light transmittance of 85% or more. However, the haze value may be intentionally increased. is there.

  In the present invention, the term “retardation film” is used, but it is meant to include “film” or “sheet”.

  Moreover, you may provide layers, such as a hard coat, an ultraviolet absorption layer, a reflection layer, on the surface of retardation film.

  Examples of the transparent body constituting the transparent plate of the present invention include inorganic glass such as plate glass and organic glass such as a transparent resin plate. These transparent bodies may have a transparent hard coat layer, and not only a single plate but also a structure in which two transparent bodies are combined with an intermediate film or the like, or a structure in which transparent bodies are laminated. Etc. can be applied.

  The transparent plate of the present invention is provided not only for windshields for vehicles, ships, aircrafts, etc., but also for HUD as a separate application, and it is provided for architectural glass, partitions, etc. for various displays. It may be.

  When applied to windshields for vehicles, ships, aircraft, etc., it is preferable to provide a retardation film on the mating surface of the transparent body from the viewpoint of improving impact resistance and penetration resistance. When a retardation film is provided on the surface side, sunlight is irradiated to the retardation film via an intermediate film such as polyvinyl butyral (hereinafter PVB), which is preferable in that ultraviolet rays are absorbed to some extent and durability is improved. .

  The transparent plate of the present invention is preferably provided with a transparent reflective layer in order to enable display with high brightness and high contrast. As the transparent reflective layer, various transparent reflective layers such as metal oxides such as titanium oxide, indium oxide, and tin oxide can be used in addition to metal thin films such as Au, Ag, and Cu. The transparent reflection layer is used on the surface of the transparent body or the surface of the retardation film.

  In the present invention, since the double image of the display is considerably reduced by the retardation film, a sufficient effect can be expected even with a relatively low reflectivity that compensates for the loss of back surface reflection, and is more excellent in scratch resistance. Thinning with a medium refractive index material or the same film material is possible. Moreover, since it is not necessary to raise the reflectance to the maximum within the restrictions on the transmittance defined by the law, for example, when used for a vehicle, it is possible to obtain a good appearance in which the reflection is less noticeable.

According to the present invention, the display light can be projected onto the transparent plate, and the display light can be imaged and viewed in the front field of view of the observer. Therefore, a head-up display that displays information in the front field ( A display device such as HUD) can be provided. Therefore, the display device includes at least a display light source that emits display light and the transparent plate that reflects the display light from the display light source. The display light is reflected on the transparent plate, and the display light can be imaged in the front field of view of the observer so as to be visually recognized by the observer. (See, for example, Fig. 1)
In the present invention, the incident angle of the display light to the transparent plate is preferably in the vicinity of the Brewster angle. For example, when the observer-side outermost surface of the transparent plate is an untreated plate glass, it is preferably about 56 ± 10 °.

  As the display light source, for example, any display body that emits polarized light such as a liquid crystal display body, or any display body that emits ordinary light when combined with means for polarizing ordinary light such as an EL element provided with a circularly polarizing plate is used. it can.

  The retardation film can be bonded to the transparent body and / or the intermediate film via the adhesive or the pressure-sensitive adhesive, or directly to the intermediate film, but a known adhesive or pressure-sensitive adhesive is used. You may add a ultraviolet absorber etc. to these adhesive agents and adhesives.

Further, these layers are not necessarily integrated, and the same effect can be expected even if they are provided separately.
As the intermediate film, a known material such as PVB can be used.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto.
The material characteristic values and the like described in the present specification are obtained by the following evaluation methods.

(1) Measurement of in-plane retardation R value and three-dimensional refractive index In-plane retardation R value and three-dimensional refractive index were measured by a birefringence measuring apparatus “KOBRA-21ADH” (manufactured by Oji Scientific Instruments). .

(2) Measurement of glass transition temperature (Tg) of retardation film It was measured by “DSC2920 Modulated DSC” (manufactured by TA Instruments).

(3) Film thickness measurement It measured with the electronic micro made from Anritsu.

(4) Measurement of dimensional change rate at 140 ° C. for 1 hour Marking at intervals of 100 mm was made on the retardation film before heat treatment, and the dimensional change rate was measured by measuring the distance between the markings after heat treatment.

(5) Measurement of polymer copolymerization ratio Measurement was performed by proton NMR of “JNM-alpha600” (manufactured by JEOL Ltd.). In particular, in the case of a copolymer of bisphenol A and biscresol fluorene, heavy benzene was used as a solvent, and calculation was performed from the proton intensity ratio of each methyl group.

(6) Copolymer polymerization method The monomer structure of the polycarbonate used in Examples 1 and 2 is shown below.

  A reaction vessel equipped with a stirrer, a thermometer and a reflux condenser is charged with an aqueous sodium hydroxide solution and ion-exchanged water, and the monomers [E] and [F] having the above structure are dissolved at a molar ratio of a: b, A small amount of hydrosulfite was added. Next, methylene chloride was added thereto, and phosgene was blown in at about 20 ° C. over about 60 minutes. Furthermore, after emulsifying by adding p-tert-butyphenol, triethylamine was added and stirred at 30 ° C. for about 3 hours to complete the reaction. After completion of the reaction, the organic phase was separated and methylene chloride was evaporated to obtain a polycarbonate copolymer. The composition ratio of the obtained copolymer was almost equal to the monomer charge ratio. The material characteristic values and the like described in the present specification are obtained by the above evaluation method.

[Example 1]
The polycarbonate copolymer copolymerized by the above method with a: b = 50: 50 was dissolved in methylene chloride to prepare a dope solution having a solid content concentration of 18% by weight. A cast film was prepared from this dope solution and uniaxially stretched 1.9 times at 220 ° C., whereby the glass transition temperature was 213 ° C., the dimensional change rate was 0.08% at 140 ° C. for 1 hour, the R value was 278 nm, A retardation film having a thickness of 30 μm was obtained. Using this retardation film, a transparent plate having the structure shown in FIG. 2 was produced by the following method.

Arrangement so that incident display light is rotated by 90 ° on a transparent soda-lime inorganic glass plate (transparent body 1) having a thickness of 2 mm with an isocyanate adhesive layer (adhesive layer 1) interposed therebetween. Bonded at an angle. The same isocyanate adhesive layer (adhesive layer 2) as the adhesive layer 1 is further bonded onto this, and then bonded to a 2 mm thick soda lime inorganic glass (transparent body 2) through a PVB film to produce a transparent plate. did.
The light emitted from the liquid crystal display was made incident on the transparent plate at an incident angle of 56 ° so that the polarization vibration direction was parallel to the transparent plate.
The display on the transparent plate was clearly visible without a double image.

[Example 2]
The polycarbonate copolymer copolymerized by the above method with a: b = 63: 37 was dissolved in methylene chloride to prepare a dope solution having a solid concentration of 18% by weight. A cast film was prepared from this dope solution and uniaxially stretched 2.1 times at 225 ° C. to obtain a glass transition temperature of 220 ° C., a dimensional change rate of 0.04% at 140 ° C. for 1 hour, an R value of 278 nm, and a thickness. A retardation film having a thickness of 40 μm was obtained. A transparent plate was produced in the same configuration as in Example 1 except that this retardation film was used.
The display on the transparent plate was clearly visible without a double image.

[Example 3]
“APEC” manufactured by Bayer was dissolved in methylene chloride to prepare a dope solution having a solid concentration of 18% by weight. A cast film was prepared from this dope solution and uniaxially stretched 1.2 times at 225 ° C. to obtain a glass transition temperature of 218 ° C., a dimensional change rate of 0.08% at 140 ° C. for 1 hour, an R value of 278 nm, and a thickness. A retardation film having a thickness of 30 μm was obtained. A transparent plate was produced in the same configuration as in Example 1 except that this retardation film was used.
The display on the transparent plate was clearly visible without a double image.

[Comparative Example 1]
A trade name “Panlite” C1400QJ manufactured by Teijin Chemicals Ltd. was dissolved in methylene chloride to prepare a dope solution having a solid concentration of 18% by weight. A cast film was prepared from this dope solution, and uniaxially stretched 1.2 times at 165 ° C., so that the glass transition temperature was 158 ° C., the dimensional change rate at 140 ° C. for 1 hour was 0.59%, R value was 278 nm, thickness A retardation film having a thickness of 30 μm was obtained. A transparent plate was produced in the same configuration as in Example 1 except that this retardation film was used.
The display on the transparent plate partially had a double image, and there were portions where bubbles were generated, which was uneven and unclear.

[Comparative Example 2]
Example 1 except that “ZEONOR FILM” manufactured by Optes Co., Ltd., having a glass transition temperature of 145 ° C., 140 ° C. for 1 hour, a dimensional change rate of 3.2%, an R value of 275 nm, and a thickness of 40 μm was used as the retardation film. A transparent plate was produced with the same configuration.
The display on the transparent plate partially had a double image, bubbles were generated on the entire surface, and it was uneven and unclear.

[Comparative Example 3]
A trade name “PVA117” manufactured by Kuraray Co., Ltd. was dissolved in hot water to prepare a dope solution having a solid concentration of 10% by weight. A cast film was prepared from this dope solution and uniaxially stretched to obtain a retardation film having a glass transition temperature of 150 ° C., a dimensional change rate of 1.2% at 140 ° C. for 1 hour, an R value of 278 nm, and a thickness of 30 μm. . A transparent plate was produced in the same configuration as in Example 1 except that this retardation film was used.
The display on the transparent plate was partially non-uniform and unclear with a double image.

  The transparent plate of the present invention can be applied to a display device such as a HUD or the like for displaying information in a vehicle, ship, aircraft, or other front field of view with high display quality that makes it difficult to see a double image.

It is a conceptual diagram of the display apparatus of this invention. It is an example of the transparent plate in Example 1 of this invention.

Explanation of symbols

1: Transparent plate 2: Observer 3: Display light source 4: Display light projected on the transparent plate 5: Display light reflected on the transparent plate and visually recognized in the observer's front visual field 6: Observer's front visual field 7 : Transparent body 1
8: Adhesive layer 1
9: Retardation film 10: Adhesive layer 2
11: Intermediate film 12: Transparent body 2

Claims (8)

  A transparent plate for use in a display device that reflects the display light from the display light source to form an image of the display light in the front field of view of the observer so that the observer visually recognizes the transparent plate, A transparent plate comprising at least one transparent body and a retardation film, wherein the retardation film has a glass transition temperature of 180 ° C. or more and a thickness of 60 μm or less.   The transparent plate according to claim 1, wherein the retardation film has a dimensional change rate of 0.5% or less when treated at 140 ° C for 1 hour.   The transparent plate according to claim 1, wherein the retardation film is made of a polycarbonate resin.   The transparent plate according to claim 3, wherein the polycarbonate resin has a fluorene skeleton. The polycarbonate resin is represented by the following formula (A)

(In the above formula (A), R _{1 to} R ₈ are each independently at least one group selected from a hydrogen atom, a halogen atom and a hydrocarbon group having 1 to 6 carbon atoms, and X is the following formula (X):

R ₉ and R ₁₀ are each independently a hydrogen atom, a halogen atom or an alkyl group having 1 to 3 carbon atoms. )
And a repeating unit represented by the following formula (B)

(In the above formula (B), R _{11 to} R ₁₈ are each independently at least one group selected from a hydrogen atom, a halogen atom and a hydrocarbon group having 1 to 22 carbon atoms, and Y represents the following formula group (Y):

Here, R _{19 to} R ₂₁ , R ₂₃ and R ₂₄ are each independently at least one group selected from a hydrogen atom, a halogen atom and a hydrocarbon group having 1 to 22 carbon atoms, and R ₂₂ and R ₂₅ is at least one group independently selected from a hydrocarbon group having 1 to 20 carbon atoms, and Ar _{1 to} Ar ₃ are each independently at least one group selected from an aryl group having 6 to 10 carbon atoms. It is. )
A polycarbonate copolymer and / or blend comprising the repeating unit represented by formula (A), wherein the repeating unit represented by the formula (A) accounts for 10 to 90 mol% of the total of the repeating units constituting the polycarbonate. The transparent plate according to claim 4, which is a body. The polycarbonate resin is represented by the following formula (C)

(In the formula (C), R _{26 to} R ₂₇ are each independently selected from a hydrogen atom and a methyl group.) The repeating unit represented by 10 to 90 mol% of the whole is represented by the following formula (D)

(In the formula (D), R _{28 to} R ₂₉ are each independently selected from a hydrogen atom and a methyl group.)
The transparent plate according to claim 5, wherein the repeating unit represented by is a polycarbonate copolymer and / or a blend that accounts for 90 to 10 mol% of the total of the repeating units constituting the polycarbonate.   The transparent plate in any one of Claims 1-6 in which a phase difference film is located between two transparent bodies.   A display device comprising at least the transparent plate according to any one of claims 1 to 7 and a display light source, wherein the observer reflects the display light from the display light source on the transparent plate. A display device in which the display light is imaged in the front visual field of the observer so that the observer can visually recognize the display light.

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