Translucent resin sheet, projection type display and movable body
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- SUMITOMO BAKELITE CO LTD
- Filing Date
- 2025-02-27
- Publication Date
- 2026-07-07
Smart Images
Figure 00000000_0000_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to a light-transmitting resin sheet, a projection display device, and a moving object. [Background technology]
[0002] 2. Description of the Related Art In recent years, head-up display devices have become known as projection-type displays mounted on moving objects such as automobiles (see, for example, Patent Document 1).
[0003] The head-up display device described in Patent Document 1 is a device that obtains a virtual image by reflecting an image displayed on a display device (display unit) such as a liquid crystal display or a CRT using a mirror and projecting it onto a curved windshield that is provided in a vehicle. In this head-up display device, a housing that houses the display unit is provided inside the dashboard, and an exit window that emits the display image is formed in this housing.
[0004] It has been proposed to place (attach) a translucent cover member (translucent resin sheet) on this exit window, the translucent cover member having a polarizing layer made up of a polarizer that generates polarized light, and protective layers made mainly of a resin material laminated on both sides of the polarizing layer (see, for example, Patent Document 2).
[0005] Furthermore, the light-transmitting cover member having such a configuration is punched out to correspond to the shape of the exit window of the housing, and then is attached to this exit window in a curved state in which a recess is formed in the center.
[0006] However, there was a problem in that cracks would occur in the light-transmitting cover member when punching out the light-transmitting cover member to correspond to the shape of the exit window, or when bending the light-transmitting cover member to form a recess in the center.
[0007] Furthermore, since the head-up display device having such a configuration is installed inside the dashboard, there is a problem that the translucent cover member discolors due to exposure of the dashboard to high temperatures, particularly in summer, and as a result, the projected image (virtual image) formed on the screen (windshield) is projected on the screen in a color tone different from the designed color tone. [Prior art documents] [Patent documents]
[0008] [Patent Document 1] JP 2015-49464 A [Patent Document 2] JP 2015-55679 A Summary of the Invention [Problem to be solved by the invention]
[0009] An object of the present invention is to provide a translucent resin sheet in which the occurrence of cracks is appropriately suppressed or prevented even when punched out into a specified shape or even when deformed into a curved state, and in which discoloration is appropriately suppressed or prevented even when exposed to high temperatures, and to provide a projection-type display device and a mobile object that are equipped with such a translucent resin sheet and are highly reliable. [Means for solving the problem]
[0010] Such an object can be achieved by the present invention described in the following (1) to (11). (1) A light-transmitting resin sheet used for a light-transmitting cover member capable of transmitting light, a polarizing layer including a polarizer that generates polarized light of the light; a protective layer provided on each of both surfaces of the polarizing layer and made mainly of a resin material; When the moisture content in the light-transmitting resin sheet is A [%] and the total thickness of the two protective layers provided on both sides of the polarizing layer is B [mm], the relational formula A·B(1) [mm·%] of the product of the content A and the total thickness B when the light-transmitting resin sheet is stored for 23 hours under conditions of a temperature of 25°C and a humidity of 50% Rh satisfies the relationship 0.20≦A·B(1)≦0.70.
[0011] (2) The light-transmitting resin sheet according to the above item (1), wherein when the light-transmitting resin sheet is stored for 22 hours under conditions of a temperature of 35°C and a humidity of 20% Rh, a relational formula A·B(2) [mm·%] of the product of the content A and the total thickness B satisfies the relationship 0.10≦A·B(2)≦0.42.
[0012] (3) The light-transmitting resin sheet according to (1) or (2) above, which satisfies that after storing the light-transmitting resin sheet for 1000 hours under conditions of a temperature of 105°C and a humidity of 0% Rh, the color change of the light-transmitting resin sheet is less than ΔE13.5 as measured in accordance with ISO11664-4.
[0013] (4) The protective layer is a single layer body mainly composed of the resin material, The light-transmitting resin sheet according to any one of (1) to (3) above, wherein the resin material is a polycarbonate-based resin.
[0014] (5) The light-transmitting resin sheet according to any one of (1) to (4) above, wherein the polarizing layer has a thickness of 5 μm or more and 60 μm or less.
[0015] (6) The light-transmitting resin sheet according to any one of (1) to (5) above, wherein the protective layer has a thickness of 0.07 mm or more and 0.80 mm or less.
[0016] (7) The light-transmitting resin sheet according to any one of (1) to (6), wherein the protective layer and the polarizing layer are bonded to each other via a bonding layer.
[0017] (8) The light-transmitting resin sheet according to the above (7), wherein the bonding layer has a thickness of 0.005 mm or more and 0.04 mm or less.
[0018] (9) The light-transmitting resin sheet according to any one of (1) to (8) above, which is used as the light-transmitting cover member that transmits light emitted from a projection display device.
[0019] (10) A projection type display device comprising the light-transmitting resin sheet according to (9) above as the light-transmitting cover member.
[0020] (11) A moving object comprising the projection type display device according to (10) above. Effect of the Invention
[0021] According to the present invention, there is provided a light-transmitting resin sheet including a polarizing layer made of a polarizer and protective layers mainly made of a resin material, each of which is provided on both sides of the polarizing layer. In the present invention, when the moisture content in the light-transmitting resin sheet is A [%] and the total thickness of the two protective layers provided on both sides of the polarizing layer is B [mm], when the light-transmitting resin sheet is stored for 23 hours under conditions of a temperature of 25°C and a humidity of 50% Rh, a relational expression A·B(1) [mm·%] of the product of the moisture content A and the total thickness B satisfies the relationship 0.20≦A·B(1)≦0.70. Therefore, for example, even if a translucent resin sheet is punched out to correspond to the shape of an exit window of a housing of a projection display as a translucent cover member for transmitting the emitted light emitted from the projection display, and the translucent resin sheet is attached in a curved state to correspond to the exit window, the occurrence of cracks in the translucent resin sheet (translucent cover member) can be appropriately suppressed or prevented. Furthermore, even if the projection display is exposed to high temperatures such as a dashboard in summer, discoloration of the translucent resin sheet (translucent cover member) can be appropriately suppressed or prevented. Therefore, the emitted light that has passed through the translucent cover member can be reliably projected onto the screen in the color tone as designed. [Brief description of the drawings]
[0022] [Figure 1]FIG. 1 is a side view showing an embodiment of a head-up display device for an automobile having a light-transmitting resin sheet of the present invention as a light-transmitting cover member. [Diagram 2] FIG. 2 is an enlarged cross-sectional view of an area [A] enclosed by a dashed line in FIG. [Diagram 3] FIG. 3 is an enlarged cross-sectional view of the light-transmitting resin sheet of the present invention applied to the light-transmitting cover member in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a light-transmitting resin sheet, a projection type display device, and a moving object according to the present invention will be described in detail with reference to preferred embodiments shown in the accompanying drawings.
[0024] First, before describing the light-transmitting resin sheet and the moving body of the present invention, a head-up display device (projection type display) for an automobile having the light-transmitting resin sheet of the present invention as a light-transmitting cover member will be described. That is, a head-up display device to which the projection type display of the present invention is applied will be described.
[0025] <Head-up display device> FIG. 1 is a side view showing an embodiment of a head-up display device for an automobile having the light-transmitting resin sheet of the present invention as a light-transmitting cover member, FIG. 2 is an enlarged cross-sectional view of the area [A] surrounded by a dashed line in FIG. 1, and FIG. 3 is an enlarged cross-sectional view of the light-transmitting resin sheet of the present invention applied to the light-transmitting cover member in FIG. 2. In the following, for convenience of explanation, the upper side in FIG. 1 to FIG. 3 is referred to as "upper" or "upper", and the lower side is referred to as "lower" or "lower". In addition, the left side in FIG. 1 and FIG. 2 is referred to as "front" or "forward", and the right side is referred to as "rear" or "rear". In addition, in FIG. 3, the light-transmitting cover member is illustrated in a flat state and is illustrated in an exaggerated thickness direction for ease of understanding.
[0026] 1, a head-up display device 10 is mounted on an automobile 100. The head-up display device 10 is built into an upper portion of a dashboard 101 of the automobile 100.
[0027] As shown in FIG. 2, the head-up display device 10 includes a display unit 11, a reflecting member 12, and a housing 13.
[0028] In this embodiment, the display unit 11 is configured as a liquid crystal display and emits a display image LS as emitted light, and is configured to form a full-color display image LS by emitting light of each of the colors red (R), green (G), and blue (B) that constitute each pixel in the display image LS from the display unit 11.
[0029] The reflecting member 12 is composed of, for example, a mirror, and is capable of reflecting the display image LS from the display unit 11. The display image LS reflected by the reflecting member 12 is projected onto the rear surface 102a (inner surface) of the windshield 102, using the windshield 102 as a screen. This projected light is then recognized by the driver H as the display image LS (see FIGS. 1 and 2).
[0030] 2, the storage body 13 (housing) is box-shaped, and stores therein the display unit 11, the reflecting member 12, and other components that constitute the head-up display device 10. The storage body 13 also has a window portion 131 that is an opening that opens toward the windshield 102. Through this window portion 131, the display image LS is emitted as outgoing light to the outside of the storage body 13, i.e., toward the windshield 102.
[0031] In addition, the light-transmitting cover member 1 having light-transmitting properties is installed (mounted) in a curved state in which a recess is formed in the center and the light-transmitting cover member 1 is curved so that the light-transmitting cover member 1 is convex on the side of the light-transmitting cover member 13 and concave on the side of the windshield 102, so as to cover the window portion 131. This allows the display image LS to be emitted toward the windshield 102, and prevents foreign matter such as dust and dirt from entering the light-transmitting cover member 13 through the window portion 131. This prevents the display image LS of the display unit 11 and the reflective member 12 from becoming cloudy or dirty due to the foreign matter. In addition, by making the light-transmitting cover member 1 be in a curved state in which a recess is formed, the light-transmitting cover member 1 is easily able to reflect sunlight, and can appropriately suppress the intrusion of sunlight into the light-transmitting cover member 13. In addition, for example, the light-transmitting cover member 1 can be prevented from protruding from the dashboard 101, and therefore the light-transmitting cover member 1 can be prevented from blocking the driver H's view.
[0032] The light-transmitting cover member 1 is made of the light-transmitting resin sheet of the present invention, which is capable of transmitting light, and includes a polarizing layer 2 made of a polarizer that generates polarized light of the light, and protective layers 3A and 3B mainly made of a resin material that are provided on both sides of the polarizing layer 2. When the moisture content (moisture content) of the light-transmitting resin sheet (light-transmitting cover member 1) is A [%] and the total thickness of the protective layers 3A and 3B is B [mm], the light-transmitting resin sheet (light-transmitting cover member 1) is stored for 23 hours under conditions of a temperature of 25°C and a humidity of 50% Rh, and the product of the moisture content A and the total thickness B satisfies the relationship 0.20≦A·B(1)≦0.70.
[0033] In this way, by forming the light-transmitting cover member 1 from the light-transmitting resin sheet of the present invention having optical transparency, the light-transmitting resin sheet is punched out as the light-transmitting cover member 1 in accordance with the shape of the window portion 131 (exit window) of the storage body 13 (housing) of the head-up display device 10 (projection display device). Furthermore, even if the light-transmitting resin sheet is attached in a curved state corresponding to the window portion 131 as shown in FIG. 2, it is possible to appropriately suppress or prevent the occurrence of cracks in the light-transmitting cover member 1. Furthermore, due to the dashboard 101 being exposed to high temperatures in the summer, the head-up display device 10 provided in the dashboard 101 is also exposed to high temperatures. However, in this way, even if the head-up display device 10 (light-transmitting cover member 1) is exposed to high temperatures, it is possible to appropriately suppress or prevent the occurrence of discoloration in the light-transmitting cover member 1. Therefore, the display image LS (emitted light) emitted from the display unit 11 can be reliably projected in the designed color tone onto the rear surface 102a of the windshield 102 serving as a screen.
[0034] Hereinafter, each layer constituting the light-transmitting cover member 1, that is, the light-transmitting resin sheet of the present invention, will be described.
[0035] 3, the light-transmitting cover member 1 is capable of transmitting light, and in this embodiment, is a laminate including a polarizing layer 2, bonding layers 4A and 4B, and protective layers 3A and 3B. Each layer will be described below.
[0036] (Polarizing layer 2) The polarizing layer 2 is an intermediate layer located at the center in the thickness direction of the light-transmitting cover member 1 (light-transmitting resin sheet), and is a portion whose thickness is constant in the surface direction of the light-transmitting cover member 1.
[0037] This polarizing layer 2 functions as a polarizer that extracts linearly polarized light having a polarization plane in a predetermined direction from the light passing through the light-transmitting cover member 1. As a result, the light passing through the light-transmitting cover member 1 is polarized.
[0038] In addition, it is desirable that the polarization degree of the polarizing layer 2 is as close to 100% as possible, specifically, it is preferably 80.0% to 98.0%, more preferably 85.0% to 98.0%, which allows the polarizing layer 2 to reliably function as a polarizer.
[0039] Such a polarizing layer 2 is not particularly limited as long as it is a film having the above-mentioned functions, and examples thereof include a polymer film composed of polyvinyl alcohol (PVA), partially formalized polyvinyl alcohol, polyethylene vinyl alcohol, polyvinyl butyral, polycarbonate, ethylene-vinyl acetate copolymer partially saponified product, etc., which is dyed by adsorbing a dichroic substance such as iodine or a dichroic dye and uniaxially stretched, and a polyene-based oriented film such as a dehydrated product of polyvinyl alcohol or a dehydrochlorinated product of polyvinyl chloride.
[0040] Among these, the polarizing layer 2 is preferably a film obtained by adsorbing iodine or a dichroic dye to a polymer film mainly made of polyvinyl alcohol (PVA), dyeing it, and uniaxially stretching it. Polyvinyl alcohol (PVA) is a material that is excellent in transparency, heat resistance, affinity with the dyeing agent iodine or dichroic dye, and orientation during stretching. Therefore, the polarizing layer 2 mainly made of PVA has excellent heat resistance and polarizing ability.
[0041] After the polymer film is dyed with a dichroic dye or the like, the polymer film is dried. By appropriately setting the drying conditions, it is possible to relatively easily obtain a light-transmitting cover member 1 that satisfies the relationship 0.20≦A·B(1)≦0.70.
[0042] The dichroic dye is not particularly limited, but examples thereof include Brilliant Blue 6B, Solophenyl Blue FGLE 220%, Solophenyl Blue GL 250%, Kayacelon Blue C-2R, Chlorazol Black BH, Direct Paper Blue STL, Solarus Rubine BLN, TOA Scarlet 4BS, EVERPULP ORENGE 2G, Hamadai Paper Yellow R 125%, Direct Fast Orange S Conc, Benzopurpurine, Diacotton Fast Orange WS, Direct Fast Orange S, AIZEN Primula Scarlet GSH, JAPANSOL FAST BLACK D conc., and the like, and one or more of these can be used in combination.
[0043] In this specification, the term "main material" refers to a constituent material that is contained in an amount of 50% by weight or more among the constituent materials that make up the layer that contains this substance.
[0044] The thickness of the polarizing layer 2 is not particularly limited, and is, for example, preferably from 5 μm to 60 μm, and more preferably from 10 μm to 40 μm. If the thickness is less than the lower limit, the polarizing layer 2 may not function sufficiently as a polarizer, and even if the thickness exceeds the upper limit, further improvement in the function as a polarizer cannot be expected.
[0045] The refractive index of the polarizing layer 2 is not particularly limited, and is, for example, preferably from 1.50 to 1.60, and more preferably from 1.52 to 1.55.
[0046] (Protective layer 3A, 3B) As shown in FIG. 3, a protective layer 3A is disposed on the upper surface of the polarizing layer 2, and a protective layer 3B is disposed on the lower surface thereof. This not only protects the polarizing layer 2, but also functions as a water vapor barrier layer that prevents water vapor (moisture) from reaching the polarizing layer 2.
[0047] These protective layers 3A and 3B are not particularly limited, but are composed of a single layer body mainly made of a resin material such as a polyamide resin, a polycarbonate resin, or a cellulose resin such as triacetyl cellulose, and one or more of these may be used in combination. Among them, it is preferable that the protective layers 3A and 3B are mainly made of a polyamide resin or a polycarbonate resin, and it is more preferable that the protective layers 3A and 3B are mainly made of a polycarbonate resin.
[0048] Polycarbonate-based resins are excellent in transparency (light transmissibility) and mechanical strength such as rigidity, and can therefore improve the transparency and impact resistance of the light-transmitting cover member 1. Among the above-mentioned resin materials, the water vapor barrier properties are best in the order of polycarbonate-based resins, polyamide-based resins, and cellulose-based resins, and polycarbonate-based resins can be said to be a resin material with particularly good water vapor barrier properties, so that it is relatively easy to obtain a light-transmitting cover member 1 that satisfies the relationship 0.20≦A·B(1)≦0.70.
[0049] The polyamide resin is not particularly limited, and various resins can be used, such as alicyclic polyamide and semi-aromatic polyamide. Alicyclic polyamide is a material with excellent impact resistance. Therefore, the translucent cover member 1 can exhibit excellent impact resistance. Semi-aromatic polyamide is a material with a high elastic modulus. Therefore, the translucent cover member 1 can have excellent resistance to stress such as bending.
[0050] In this specification, semi-aromatic polyamide refers to a polyamide in which one of the dicarboxylic acid and diamine monomers constituting the polyamide is an aromatic compound and the other is an aliphatic compound, and specifically, can be represented by the following formula (1B).
[0051] [ka] (However, R in formula (1B) 1 and R 2one of which is a divalent aromatic substituent and the other is a divalent aliphatic substituent, and n is an integer of 2 or greater.
[0052] The polyamide may be a copolymer (random copolymer, block copolymer, etc.) containing two or more kinds of monomers of at least one of dicarboxylic acid and diamine.
[0053] In addition, R in the above formula (1B) 1 , R 2 Of these, the aromatic substituent is preferably a group represented by the following formula (2B).
[0054] [ka] (In formula (2B), l and m each independently represent an integer of 0 or more and 2 or less.)
[0055] This makes it possible to more suitably protect the polarizing layer 2 and to further improve the processability of the light-transmitting cover member 1. Furthermore, when retardation is imparted to the protective layers 3A and 3B, it is possible to more easily control the retardation by stretching the protective layers 3A and 3B.
[0056] R in the above formula (1B) 1 , R 2 Of these, the aliphatic substituent is preferably a group having 4 to 18 carbon atoms, more preferably a hydrocarbon group having 4 to 18 carbon atoms, and even more preferably a saturated hydrocarbon group having 4 to 18 carbon atoms. This allows the workability of the light-transmitting cover member 1 to be further improved.
[0057] Furthermore, the semi-aromatic polyamide is preferably a compound containing an aromatic dicarboxylic acid and an aliphatic diamine as constituent monomers. This makes it possible to more suitably protect the polarizing layer 2 and to further improve the processability of the light-transmitting cover member 1. In addition, it is easier to control the retardation by stretching.
[0058] An alicyclic polyamide has an alicyclic chemical structure in its molecule, and may have an alicyclic chemical structure in its main chain structure or may have an alicyclic chemical structure in its side chain structure.
[0059] Examples of the alicyclic polyamide include compounds in which at least one of the dicarboxylic acid and diamine monomers constituting the polyamide has an alicyclic chemical structure, and specifically, for example, can be represented by the following formula (3B).
[0060] [ka] (In formula (3B), R 3 , R 4 are each independently a hydrogen atom or a hydrocarbon group having 4 or less carbon atoms, o is an integer of 2 or more and 14 or less, p is an integer of 0 or more and 6 or less, and n is an integer of 2 or more.
[0061] The polycarbonate resin is not particularly limited and various resins can be used, but among them, aromatic polycarbonate resins are preferable. Aromatic polycarbonate resins have aromatic rings in their main chains, which can further improve the strength of the light-transmitting cover member 1.
[0062] The aromatic polycarbonate resin is synthesized, for example, by an interfacial polycondensation reaction between bisphenol and phosgene, or an ester exchange reaction between bisphenol and diphenyl carbonate.
[0063] Examples of bisphenols include bisphenol A and bisphenol (modified bisphenol) which is the source of the repeating unit of polycarbonate represented by the following formula (1A).
[0064] [ka] (In formula (1A), X is an alkyl group having 1 to 18 carbon atoms, an aromatic group, or a cyclic aliphatic group; Ra and Rb are each independently an alkyl group having 1 to 12 carbon atoms; m and n are each an integer of 0 to 4; and p is the number of repeating units.)
[0065] Specific examples of bisphenols that are the source of the repeating units of the polycarbonate represented by the formula (1A) include 4,4'-(pentane-2,2-diyl)diphenol, 4,4'-(pentane-3,3-diyl)diphenol, 4,4'-(butane-2,2-diyl)diphenol, 1,1'-(cyclohexanediyl)diphenol, 2-cyclohexyl-1,4-bis(4-hydroxyphenyl)benzene, 2,3-biscyclohexyl-1,4-bis(4-hydroxyphenyl)benzene, 1,1'-bis(4-hydroxy-3-methylphenyl)cyclohexane, and 2,2'-bis(4-hydroxy-3-methylphenyl)propane, and any of these may be used alone or in combination of two or more.
[0066] In particular, the polycarbonate resin is preferably a bisphenol-type polycarbonate resin having a skeleton derived from bisphenol, which is the main component. By using such a bisphenol-type polycarbonate resin, the light-transmitting cover member 1 can exhibit even greater strength.
[0067] Furthermore, the protective layers 3A and 3B may contain other components in addition to the resin material contained as the main material. Such components are not particularly limited, but may include, for example, a resin material other than the main material, a colorant such as a dye, a filler, an alignment aid, a stabilizer (such as a heat stabilizer, an ultraviolet absorber, and an antioxidant), a plasticizer, a colorant, a flame retardant, an antistatic agent, and a viscosity adjuster.
[0068] In this case, the content of the resin material in the protective layers 3A and 3B is not particularly limited, but is preferably 75 parts by mass or more, and more preferably 85 parts by mass or more, per 100 parts by mass of the protective layers 3A and 3B. By setting the content of the resin material within the above range, a light-transmitting cover member 1 having excellent strength can be obtained.
[0069] The protective layers 3A and 3B may be made of the same or different materials.
[0070] Furthermore, when retardation (phase difference; birefringence × thickness) is to be exhibited in the protective layers 3A and 3B, it is preferable that the retardation of the protective layer 3A is different from the retardation of the protective layer 3B, and it is preferable that the retardation of the protective layer 3A is lower than the retardation of the protective layer 3B.
[0071] As a result, the protective layer 3B is easily deformed in a direction in which the curvature of curvature becomes smaller due to thermal contraction, but the protective layer 3A can be made difficult to deform due to thermal contraction. Therefore, as shown in FIG. 2, by applying a translucent resin sheet to the translucent cover member 1 provided in the head-up display device 10, it is used in a curved state, and in this case, it is preferable to make the curved shape so that the protective layer 3B is located on the curved convex surface side and the protective layer 3A is located on the curved concave surface side. In this case, the protective layer 3B has a relatively high thermal contraction rate and is relatively prone to thermal deformation, but in the translucent cover member 1, the protective layer 3A exerts a function of suppressing the thermal deformation of the protective layer 3B. Therefore, the translucent cover member 1 as a whole can be prevented from excessive deformation due to heat. As a result, it is possible to appropriately suppress or prevent the translucent cover member 1 from thermally deforming due to the dashboard 101 being exposed to high temperatures in the summer.
[0072] The retardation of the protective layer 3A is preferably 0 nm or more and 500 nm or less, more preferably 50 nm or more and 350 nm or less. The retardation of the protective layer 3B is preferably 2600 nm or more and 8000 nm or less, more preferably 3500 nm or more and 6500 nm or less. This allows the retardation of the protective layer 3A to be sufficiently low, and the retardation of the protective layer 3B to be sufficiently high. Therefore, the effect obtained by making the retardation of the protective layer 3A lower than that of the protective layer 3B can be more significantly exhibited. In addition, the polarization performance of the light-transmitting cover member 1 can be sufficiently improved.
[0073] The difference in retardation between the protective layers 3A and 3B can be realized by varying the constituent materials contained in the layers, the thicknesses, and further the stretching ratios.
[0074] The stretching ratio of the protective layer 3A is not particularly limited, but is preferably, for example, 0.95 to 1.1 so as to be set to the magnitude of the retardation. The stretching ratio of the protective layer 3B is not particularly limited, but is preferably, for example, 1.5 to 3.5 so as to be set to the magnitude of the retardation.
[0075] Moreover, it is preferable that the protective layer 3A, the protective layer 3B and the polarizing layer 2 are stretched in the same direction, thereby enabling the polarization performance of the light-transmitting cover member 1 to be further improved.
[0076] The thickness of the protective layers 3A and 3B is, for example, preferably 0.07 mm or more and 0.80 mm or less, more preferably 0.10 mm or more and 0.50 mm or less, and even more preferably 0.12 mm or more and 0.35 mm or less. By setting the thickness of the protective layers 3A and 3B within this range, the protective layers 3A and 3B can reliably perform the function of protecting the polarizing layer 2. Therefore, when the light-transmitting cover member 1 is attached to cover the window portion 131 of the housing body 13 in a curved state, the light-transmitting cover member 1 can reliably perform the function as a cover member covering the window portion 131. In addition, it is relatively easy to obtain a light-transmitting cover member 1 that satisfies the relationship 0.20≦A·B(1)≦0.70.
[0077] Furthermore, the thicknesses of the protective layers 3A and 3B may be the same or different, so long as the light-transmitting cover member 1 satisfies the relationship 0.20≦A·B(1)≦0.70.
[0078] Furthermore, the refractive index of the protective layers 3A and 3B is not particularly limited, but is preferably, for example, 1.45 or more and 1.66 or less, and more preferably 1.48 or more and 1.60 or less.
[0079] In this embodiment, the protective layers 3A and 3B are each configured as a single layer body mainly made of a resin material, but this is not limited to this. The protective layers 3A and 3B may each be configured as a laminate body having, for example, a first layer and a second layer mainly made of a resin material, with the first layer and the second layer being bonded together with a bonding layer.
[0080] (Joining layer 4A, 4B) The polarizing layer 2 and the protective layer 3A are bonded to each other via an adhesive layer 4A, and the polarizing layer 2 and the protective layer 3B are bonded to each other via an adhesive layer 4B.
[0081] The bonding layers 4A and 4B are various adhesives or pressure-sensitive adhesives such as a urethane adhesive, an epoxy adhesive, an acrylic adhesive, an acrylic pressure-sensitive adhesive, etc. This ensures reliable bonding between the layers, and makes it possible to obtain a light-transmitting cover member 1 that can withstand long-term use.
[0082] The thickness of the bonding layers 4A and 4B is not particularly limited, and is preferably 0.005 mm or more and 0.04 mm or less, and more preferably 0.006 mm or more and 0.015 mm or less. If the thickness of the bonding layers 4A and 4B is less than the lower limit, the adhesive strength may decrease, and if the thickness of the bonding layers 4A and 4B exceeds the upper limit, depending on the type of adhesive or pressure-sensitive adhesive, the light-transmitting cover member 1 may be distorted due to the hardening and shrinkage of the bonding layers 4A and 4B. The thicknesses of the bonding layers 4A and 4B may be different from each other, but are preferably the same.
[0083] The refractive index of the bonding layers 4A and 4B is not particularly limited, and is preferably, for example, 1.46 or more and 1.55 or less, and more preferably 1.461 or more and 1.545 or less.
[0084] The light-transmitting cover member 1 (light-transmitting resin sheet) having such a configuration has the following problems, as described in the background art above.
[0085] That is, when punching out the light-transmitting cover member 1 (light-transmitting resin sheet) corresponding to the shape of the window portion 131 (exit window) of the storage body 13 (housing) of the head-up display device 10 (projection type display device) or when bending the light-transmitting cover member 1 to form a recess in the center, there is a problem that cracks are generated in the light-transmitting cover member 1. Furthermore, the head-up display device 10 is installed inside the dashboard 101 of the automobile 100, and since the dashboard 101 is exposed to high temperatures especially in the summer, the light-transmitting cover member 1 is also heated, causing the light-transmitting cover member 1 to discolor, and as a result, there is a problem that the display image LS (projected image) formed on the back surface 102a of the windshield 102 as a screen is projected on the back surface 102a in a color tone different from the designed color tone.
[0086] The present inventors have conducted extensive research with the aim of solving these problems, and have found that these problems are related to the amount of moisture contained in the light-transmitting cover member 1, and in particular, the polarizing layer 2. More specifically, it has been found that if the amount of moisture contained in the light-transmitting cover member 1 (polarizing layer 2) is too low, the cracks will occur in the light-transmitting cover member 1, and if the amount of moisture contained in the light-transmitting cover member 1 (polarizing layer 2) is too high, the discoloration will occur in the light-transmitting cover member 1 when it is exposed to high temperatures.
[0087] The present inventor further investigated the amount of moisture contained in the light-transmitting cover member 1 (polarizing layer 2) and found that the amount of moisture in the light-transmitting cover member 1 (particularly the polarizing layer 2) over a long period of time is closely related to the moisture amount of the light-transmitting cover member 1 as a whole and the thicknesses of the protective layers 3A and 3B. Specifically, when the moisture content in the light-transmitting cover member 1 (light-transmitting resin sheet) is A [%] and the total thickness of the protective layers 3A and 3B is B [mm], the light-transmitting cover member 1 (light-transmitting resin sheet) is stored for 23 hours under conditions of a temperature of 25° C. and a humidity of 50% Rh, and the product of the moisture content A and the total thickness B satisfies the relationship A·B(1) [mm·%], where A is the moisture content in the light-transmitting cover member 1 (light-transmitting resin sheet) and B is the total thickness B, and the product satisfies the relationship 0.20≦A·B(1)≦0.70. This led to the completion of the present invention.
[0088] In other words, by making the relational expression A·B(1) [mm·%] satisfy the relationship of 0.20≦A·B(1), it is possible to appropriately suppress or prevent cracks from occurring in the light-transmitting cover member 1 when punching out the light-transmitting cover member 1 (light-transmitting resin sheet) to correspond to the shape of the window portion 131 (exit window) of the storage body 13 (housing) of the head-up display device 10 (projection type display) or when bending the light-transmitting cover member 1 to form a recess in the center.
[0089] Furthermore, when the dashboard 101 is exposed to high temperatures in summer, the head-up display device 10 provided in the dashboard 101 is also exposed to high temperatures. However, when the relational expression A·B(1) [mm·%] satisfies A·B(1)≦0.70, discoloration of the light-transmitting cover member 1 can be appropriately suppressed or prevented even when the head-up display device 10 (light-transmitting cover member 1) is exposed to high temperatures. Therefore, the display image LS (emitted light) emitted from the display unit 11 can be reliably projected in the designed color tone onto the rear surface 102a of the windshield 102 serving as a screen.
[0090] When the water vapor barrier for the polarizing layer 2 is taken into consideration, it is presumed that not only the thicknesses of the protective layers 3A and 3B laminated on the polarizing layer 2 but also the thicknesses of the bonding layers 4A and 4B are related to the water vapor barrier for the polarizing layer 2. However, in consideration of the relationship between the constituent materials contained in the protective layers 3A, 3B and the bonding layers 4A, 4B described above, and further the thicknesses of the protective layers 3A, 3B and the bonding layers 4A, 4B, it is considered that it is a reasonable judgment as a basis for setting parameters to specify the magnitude of the relational expression A·B(1) by setting the total thickness of the protective layers 3A and 3B as B [mm], excluding the thicknesses of the bonding layers 4A and 4B.
[0091] Furthermore, the moisture content A in the light-transmitting cover member 1 is, for example, preferably 0.150% or more and 1.800% or less, more preferably 0.200% or more and 1.200% or less, and even more preferably 0.400% or more and 1.000% or less. This makes it relatively easy to obtain a light-transmitting cover member 1 that satisfies the relationship 0.20≦A·B(1)≦0.70.
[0092] The moisture content A (water vapor content) [%] in the light-transmitting cover member 1 can be measured using, for example, a moisture content measuring device (manufactured by ITS Japan, "AQUATRACK 3E").
[0093] The relational expression A·B(1) [mm·%] may satisfy the relationship 0.20≦A·B(1)≦0.70, preferably 0.23≦A·B(1)≦0.52, and more preferably 0.23≦A·B(1)≦0.38. By setting A·B(1) within the above range, the above effect can be exhibited more significantly. In addition, in order to suppress the discoloration of the light-transmitting cover member 1 when exposed to high temperatures to a level that can withstand practical use while minimizing cracks during molding of the light-transmitting cover member 1, the relationship 0.42≦A·B(1)≦0.65 is preferable, and in order to consider the balance between the two, the relationship 0.46≦A·B(1)≦0.60 is more preferable.
[0094] Furthermore, the relational expression A·B(2) [mm·%] of the product of the moisture content A and the total thickness B when the light-transmitting cover member 1 is stored under different conditions, such as a temperature of 35°C and a humidity of 20% Rh for 22 hours, preferably satisfies the relationship 0.10≦A·B(2)≦0.42, and more preferably satisfies the relationship 0.17≦A·B(2)≦0.30. By setting A·B(2) within the above range, the effect obtained by setting A·B(1) within the above range can be more significantly exhibited. Note that, in order to minimize cracks during molding of the light-transmitting cover member 1 while suppressing discoloration of the light-transmitting cover member 1 during high-temperature exposure to a level that can withstand practical use, the relationship 0.32≦A·B(2)≦0.41 is preferable, and in order to consider the balance between the two, the relationship 0.33≦A·B(2)≦0.40 is more preferable.
[0095] Specifically, after storing the light-transmitting cover member 1 (light-transmitting resin sheet) under conditions of a temperature of 105° C. and a humidity of 0% Rh for 1000 hours, the color change of the light-transmitting cover member 1 measured in accordance with ISO11664-4 is preferably less than ΔE13.5, more preferably less than ΔE12.0, and even more preferably less than ΔE10.6. This means that the light-transmitting cover member 1 is appropriately suppressed or prevented from discoloring even when exposed to high temperatures.
[0096] The color change [ΔE] of the light-transmitting cover member 1 is measured in accordance with ISO11664-4 (JIS Z 8781-4) using a D65 light source at a viewing angle of 2°. * a * b * ) can be calculated based on
[0097] Although the light-transmitting resin sheet, the projection display device, and the moving object of the present invention have been described above, the present invention is not limited to these.
[0098] For example, each component constituting the projection type display device and the moving body of the present invention can be replaced with any component capable of exerting a similar function.
[0099] In the above embodiment, the light-transmitting resin sheet of the present invention has the polarizing layer 2 and the protective layers 3A and 3B laminated on the polarizing layer 2, and the polarizing layer 2 and the protective layers 3A and 3B are bonded via the bonding layers 4A and 4B. However, the present invention is not limited to this. For example, the light-transmitting resin sheet may have an intermediate layer provided at least one between the polarizing layer 2 and the bonding layers 4A and 4B, and between the protective layers 3A and 3B and the bonding layers 4A and 4B, or may have an outermost layer such as a hard coat layer laminated on at least one of the protective layers 3A and 3B. A material different from that of the protective layer may be used for the intermediate layer.
[0100] Furthermore, in the above embodiment, the projection type display of the present invention is described as being applied to a head-up display device 10 equipped in an automobile 100 as a moving body. However, moving bodies to which the head-up display device 10 can be applied are not limited to automobiles 100, and may include, for example, ships, railway vehicles, airplanes, buses, motorcycles, bicycles, forklifts, work vehicles used for specific tasks at construction sites, golf carts, etc. Furthermore, the light-transmitting resin sheet of the present invention is not limited to the use as a light-transmitting cover member of the above-mentioned head-up display device, but can also be applied to lenses of eyewear such as spectacles, sunglasses, etc. For example, the light-transmitting resin sheet of the present invention can be punched into the shape of a lens, and the light-transmitting resin sheet curved to correspond to the lens can be attached to the surface of the lens for use. EXAMPLES
[0101] The present invention will be described in more detail below with reference to examples, although the present invention is not limited to these examples in any way.
[0102] 1. Preparation of various films First, various films used in the manufacture of the light-transmitting resin sheets of each of the Examples and Comparative Examples are shown below.
[0103] (PVA film) As a PVA (polyvinyl alcohol) film, Kuraray Vinylon #7500 (manufactured by Kuraray Co., Ltd.) was prepared.
[0104] (Protective film 1) As the protective film 1, a polycarbonate resin sheet (thickness: 0.325 mm) was prepared.
[0105] (Protective film 2) As the protective film 2, a polycarbonate resin sheet (thickness: 0.250 mm) was prepared.
[0106] (Protective film 3) As the protective film 3, a polycarbonate resin sheet (thickness: 0.125 mm) was prepared.
[0107] (Protective film 4A) A polyamide resin sheet (thickness: 0.400 mm) was prepared as the protective film 4A.
[0108] (Protective film 4B) As the protective film 4B, a polyamide resin sheet (thickness: 0.200 mm) was prepared.
[0109] (Protective film 5) As the protective film 5, a triacetyl cellulose resin sheet (thickness: 0.080 mm) was prepared.
[0110] 2. Manufacturing of translucent resin sheets Example 1 <1> First, in a dyeing apparatus equipped with a swelling tank, dyeing tank, crosslinking tank, and dryer, the PVA film was stretched and dyed for 10 minutes at 40°C in an aqueous solution of dichroic dye (4 g / L Brilliant Blue 6B, 2 g / L Benzopurpurine, and 1 g / L JAPANSOL FAST BLACK D conc.), followed by crosslinking with boric acid and drying for 5 minutes at 80°C and 0% Rh to form polarizing layer 2.
[0111] <2> Next, protective films 1 were pressure-bonded as protective layers 3A and 3B to both sides of the obtained polarizing layer 2 via a one-component moisture-curing polyurethane adhesive to prepare a translucent resin sheet of Example 1 having a total thickness of 0.7 mm.
[0112] (Examples 2 to 5, 8, and 9) The above steps <2> The light-transmitting resin sheets of Examples 2 to 5, 8 and 9 were obtained in the same manner as in Example 1, except that the combinations of protective films to be pressure-bonded as protective layers 3A and 3B had layer structures shown in Table 1.
[0113] (Examples 6 and 7, Comparative Examples 1 and 2) The above steps <1> The light-transmitting resin sheets of Examples 6 and 7 and Comparative Examples 1 and 2 were obtained in the same manner as in Example 1, except that the conditions for obtaining the polarizing layer 2 by drying were the conditions shown in Table 1.
[0114] Example 10 The above steps <1> A light-transmitting resin sheet of Example 10 was obtained in the same manner as in Example 1, except that the drying of the polarizing layer 2 in step 1 was omitted.
[0115] 3. Evaluation The light-transmitting resin sheets of the respective Examples and Comparative Examples were evaluated by the following methods.
[0116] Calculation of the relationship A·B(1) First, the light-transmitting resin sheets of each of the examples and comparative examples were stored for 23 hours under conditions of a temperature of 25° C. and a humidity of 50% Rh.
[0117] Next, for the translucent resin sheet after storage under these conditions, the moisture content (moisture content) A in the translucent resin sheet was measured using a moisture content measuring device (manufactured by ITS Japan, "AQUATRACK 3E").
[0118] Then, based on the obtained moisture content A and the total thickness B of the protective layers 3A and 3B provided on the light-transmitting resin sheet, the magnitude of A·B(1) was calculated.
[0119] Calculation of the relationship A·B(2) First, the light-transmitting resin sheets of each of the Examples and Comparative Examples were stored for 22 hours under conditions of a temperature of 35° C. and a humidity of 20% Rh.
[0120] Next, for the translucent resin sheet after storage under these conditions, the moisture content (moisture content) A in the translucent resin sheet was measured using a moisture content measuring device (manufactured by ITS Japan, "AQUATRACK 3E").
[0121] Then, based on the obtained moisture content A and the total thickness B of the protective layers 3A and 3B provided on the light-transmitting resin sheet, the magnitude of A·B(2) was calculated.
[0122] <c>Bend test evaluation First, the translucent resin sheets of each Example and Comparative Example were punched out to form test pieces of 5 cm square, and then these test pieces were heated to 140° C. and subjected to a thermal bending process to form them into a curved state with a curvature radius of 80 mm. Then, 20 test pieces in this curved state were formed for each of the translucent resin sheets of each Example and Comparative Example, and the appearance of each test piece was visually observed to confirm the presence or absence of cracks in the test pieces.
[0123] <d>Heat resistance test evaluation The color change (ΔE) after storage for 1000 hours under conditions of a temperature of 105° C. and a humidity of 0% Rh for each of the light-transmitting resin sheets of the Examples and Comparative Examples was measured in accordance with ISO11664-4 (JIS Z 8781-4) using a D65 light source at a viewing angle of 2° before and after storage, as a color value (L * a * b * ) was calculated based on
[0124] The evaluation results of the thus obtained light-transmitting resin sheets of each of the Examples and Comparative Examples are shown in Table 1 below.
[0125] [Table 1]
[0126] As shown in Table 1, in the light-transmitting resin sheet in each Example, the relational expression A·B(1) [mm·%] satisfied the relationship of 0.20≦A·B(1)≦0.70. As a result, it was shown that even if the light-transmitting resin sheet was formed into a curved shape, the occurrence of cracks in the light-transmitting resin sheet could be appropriately suppressed or prevented, and even if the light-transmitting resin sheet was exposed to high temperatures, the occurrence of discoloration in the light-transmitting resin sheet could be appropriately suppressed or prevented.
[0127] In contrast, in the light-transmitting resin sheet of Comparative Example 1, the relationship A·B(1) [mm·%] was less than 0.20, and did not satisfy the relationship 0.20≦A·B(1)≦0.70. As a result, when the light-transmitting resin sheet was formed into a curved shape, cracks were generated in the light-transmitting resin sheet. Also, in the light-transmitting resin sheet of Comparative Example 2, the relationship A·B(1) [mm·%] was more than 0.70, and did not satisfy the relationship 0.20≦A·B(1)≦0.70. As a result, when the light-transmitting resin sheet was exposed to high temperatures, discoloration was observed in the light-transmitting resin sheet. [Industrial Applicability]
[0128] According to the present invention, there is provided a light-transmitting resin sheet including a polarizing layer made of a polarizer and protective layers mainly made of a resin material, each of which is provided on both sides of the polarizing layer. In the present invention, when the moisture content in the light-transmitting resin sheet is A [%] and the total thickness of the two protective layers provided on both sides of the polarizing layer is B [mm], when the light-transmitting resin sheet is stored for 23 hours under conditions of a temperature of 25°C and a humidity of 50% Rh, a relational expression A·B(1) [mm·%] of the product of the moisture content A and the total thickness B satisfies the relationship 0.20≦A·B(1)≦0.70. Therefore, for example, even if a translucent resin sheet is punched out in accordance with the shape of an exit window of a housing of a projection display as a translucent cover member for transmitting the light emitted from the projection display, and the translucent resin sheet is attached in a curved state corresponding to the exit window, the occurrence of cracks in the translucent resin sheet (translucent cover member) can be appropriately suppressed or prevented. Furthermore, even if the projection display is exposed to high temperatures such as a dashboard in summer, the translucent resin sheet (translucent cover member) can be appropriately suppressed or prevented from discoloring. Therefore, the emitted light transmitted through the translucent cover member can be reliably projected on a screen in the color tone as designed. Therefore, the present invention has industrial applicability. [Explanation of symbols]
[0129] 1. Light-transmitting cover member 2 Polarizing layer 3A protective layer 3B Protective layer 4A bonding layer 4B Bonding layer 10 Head-Up Display 11 Display section 12 Reflective material 13 Storage unit 131 Window 100 Automobiles 101 Dashboard 102 Windshield 102a Back side (inner surface) H Driver LS display image< / d> < / c>
Claims
1. A polarization layer composed of polarizers that generate polarized light, A translucent resin sheet comprising a protective layer provided on both sides of the polarizing layer and containing 50% by weight or more of a resin material, The polarizing layer has a dichroic dye, This translucent resin sheet is used in projection-type displays that are mounted on mobile devices. When the moisture content in the light-transmitting resin sheet is A [%], and the sum of the thicknesses of the two protective layers provided on both sides of the polarizing layer is B [mm], When the translucent resin sheet is stored for 23 hours under conditions of a temperature of 25°C and a humidity of 50% Rh, the relationship A・B(1) [mm・%], which is the product of the content A and the total thickness B, satisfies the relationship 0.20 ≤ A・B(1) ≤ 0.
70. A translucent resin sheet characterized in that, after being stored for 1000 hours under conditions of a temperature of 105°C and a humidity of 0% Rh, the color change of the translucent resin sheet, measured in accordance with ISO 11664-4, satisfies the condition that ΔE is less than 12.
0.
2. The translucent resin sheet according to claim 1, wherein the product of the content A and the total thickness B when the translucent resin sheet is stored for 22 hours under conditions of a temperature of 35°C and a humidity of 20% Rh, the relationship A・B(2) [mm・%] of the content A satisfies the relationship 0.10 ≤ A・B(2) ≤ 0.
42.
3. The protective layer is a single layer containing 50% by weight or more of the resin material. The translucent resin sheet according to claim 1 or 2, wherein the resin material is a polycarbonate-based resin.
4. The light-transmitting resin sheet according to claim 1, wherein the polarizing layer has a thickness of 5 μm or more and 60 μm or less.
5. The light-transmitting resin sheet according to claim 1, wherein the protective layer has a thickness of 0.07 mm or more and 0.80 mm or less.
6. The translucent resin sheet according to claim 1, wherein the protective layer and the polarizing layer are joined via a bonding layer.
7. The translucent resin sheet according to claim 6, wherein the bonding layer has a thickness of 0.005 mm or more and 0.04 mm or less.
8. The translucent resin sheet according to claim 1 is used as a translucent cover member that transmits emitted light emitted from the projection display.
9. A projection display characterized by comprising the translucent resin sheet described in claim 8 as a translucent cover member capable of transmitting light.
10. A mobile body characterized by comprising a projection-type display as described in claim 9.