Cover glass and optical apparatus

Abstract

Provided is a technology for improving the impact resistance, the high-temperature and high-humidity resistance, and the heat resistance of a cover glass for protecting an electronic device, while reducing perspective distortion of the cover glass. This cover glass for protecting an electronic device has an inside surface that faces the electronic device and an outside surface that faces a direction which is opposite to the direction the inside surface faces, and this cover glass for protecting an electronic device sequentially has a glass plate, a resin film, and an inorganic film in this order from the outside to the inside. The resin film has a film thickness of 0.01 µm to 5 µm.

Description

Cover Glasses and Optical Instruments

[0001] The present disclosure relates to cover glasses and optical instruments.

[0002] Cover glass is used as a protective plate for protecting electronic devices such as LiDAR (Light Detection and Ranging) sensors. The cover glass described in Patent Document 1 includes a conductor, a dielectric multilayer film, and a heat-generating film arranged in a desired order from the outside of a housing toward the inside of the housing. The conductor and the heat-generating film are insulated from each other, and the conductor is electrically connected to ground.

[0003] The imaging device described in Patent Document 2 includes an imaging element, a lens that focuses light onto the imaging element, and a protective plate that is located closer to the subject than the lens and is in contact with the outside air. The protective plate includes a glass plate, a resin layer that is provided in contact with a main surface of the glass plate, and an inorganic film that is provided on the resin layer. The resin layer has a thickness of 20 μm to 100 μm.

[0004] International Publication No. 2023 / 068187 International Publication No. 2017 / 170606

[0005] A cover glass that protects an electronic device has an inner surface facing the electronic device and an outer surface facing the opposite side of the inner surface. An impact may be applied to the cover glass from the outside. In this case, the cover glass bends into a concave curve facing outward. As a result, compressive stress occurs on the outer surface and tensile stress occurs on the inner surface. The tensile stress may cause cracks.

[0006] A cover glass may have, from the outside to the inside, a glass plate and an inorganic film. The inorganic film improves the optical properties of the cover glass. However, the inorganic film is easily cracked by tensile stress. If a crack in the inorganic film extends to the glass plate, a crack will also occur in the glass plate, originating from the crack in the inorganic film.

[0007] Therefore, in order to prevent cracks in the inorganic film from extending to the glass plate, it is conceivable to form a resin film between the inorganic film and the glass plate. The resin film prevents cracks from extending between the inorganic film and the glass plate. However, if the resin film has a thickness of 20 μm to 100 μm as described in Patent Document 2, the high-temperature and high-humidity resistance and heat resistance will decrease, and perspective distortion will increase.

[0008] An embodiment of the present disclosure provides a technology for improving the impact resistance, high temperature and humidity resistance, and heat resistance of a cover glass that protects an electronic device, while reducing perspective distortion.

[0009] A cover glass for protecting an electronic device according to an embodiment of the present disclosure has an inner surface facing the electronic device and an outer surface facing opposite the inner surface, and includes, from the outside to the inside, a glass plate, a resin film, and an inorganic film, in this order, wherein the resin film has a thickness of 0.01 μm to 5 μm.

[0010] According to one embodiment of the present disclosure, it is possible to improve the impact resistance, high temperature and humidity resistance, and heat resistance of a cover glass that protects an electronic device, while reducing perspective distortion.

[0011] Fig. 1 is a cross-sectional view showing an optical device according to an embodiment. Fig. 2 is a plan view showing an example of the glass plate shown in Fig. 1. Fig. 3 is a cross-sectional view showing an optical device according to a modified example. Fig. 4 is a cross-sectional view taken along line IV-IV in Fig. 3. Fig. 5 is a cross-sectional view showing an example of an impact resistance test of a cover glass.

[0012] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, the same or similar components are denoted by the same reference numerals, and their description may be omitted. In the specification, the symbol "to" indicating a numerical range means that the numerical values ​​before and after it are included as the lower and upper limits. The numerical range includes the range rounded up or down.

[0013] First, an optical device 10 according to one embodiment will be described with reference to Fig. 1. The optical device 10 includes a cover glass 20 and an electronic device 30. The cover glass 20 protects the electronic device 30. The electronic device 30 is, but is not limited to, an in-vehicle sensor, for example. The in-vehicle sensor is, for example, a LiDAR (Light Detection and Ranging) sensor.

[0014] A LiDAR sensor detects the distance to and direction of an object by irradiating the object with infrared rays and receiving the infrared rays reflected by the object. Although not shown, the LiDAR sensor includes, for example, a laser light source, an irradiation optical system that irradiates the object with infrared rays from the laser light source, a receiving optical system that guides the infrared rays reflected by the object to a receiver, and the receiver.

[0015] The on-board sensor is not limited to a LiDAR sensor, but may be an imaging sensor such as a CCD image sensor or a CMOS image sensor. The on-board sensor may further include an optical system that guides visible light to the imaging sensor. The electronic device 30 is not limited to an on-board sensor. However, it is preferable that the electronic device 30 is an optical sensor.

[0016] The optical device 10 preferably includes a housing 40. The housing 40 houses the electronic device 30. The cover glass 20 is provided at an opening of the housing 40 to prevent snow, rain, dust, and the like from entering the inside of the housing 40 and protect the electronic device 30.

[0017] When the electronic device 30 is a LiDAR sensor, the cover glass 20 is preferably an infrared pass filter. The infrared pass filter transmits infrared light and blocks visible light. This improves the sensitivity of the LiDAR sensor. Furthermore, blocking visible light makes the electronic device 30 invisible from outside the housing 40.

[0018] When the electronic device 30 is an image sensor, the cover glass 20 is preferably an infrared cut filter. The infrared cut filter transmits visible light and blocks infrared light. By transmitting visible light and blocking infrared light, an image with colors similar to those seen by the human eye can be produced.

[0019] Next, referring again mainly to FIG. 1 , a cover glass 20 according to one embodiment will be described. The cover glass 20 has an inner surface 20a facing the electronic device 30 and an outer surface 20b facing opposite the inner surface 20a. An impact may be applied to the cover glass 20 from the outside. In this case, as shown by the dashed line in FIG. 1 , the cover glass 20 bends into a concave curved surface facing outward. As a result, compressive stress occurs in the outer surface 20b and tensile stress occurs in the inner surface 20a. The tensile stress may cause cracks.

[0020] The cover glass 20 has, from the outside to the inside, a glass plate 21, a resin film 22, and an inorganic film 23, in this order. The inorganic film 23 improves the optical properties of the cover glass 20. However, the inorganic film 23 is easily broken by tensile stress. If a crack in the inorganic film 23 extends to the glass plate 21, a crack will also occur in the glass plate 21. The resin film 22 suppresses the extension of the crack between the inorganic film 23 and the glass plate 21. This improves the impact resistance of the cover glass 20.

[0021] The glass plate 21 is, for example, soda-lime glass, borosilicate glass, alkali-free glass, quartz glass, or aluminosilicate glass. From the viewpoint of impact resistance, the glass plate 21 is preferably chemically strengthened glass. Chemically strengthened glass is glass in which a compressive stress layer is formed on the surface by ion exchange at a temperature below the glass transition point. The compressive stress layer is formed by exchanging alkali metal ions contained in the glass, which have a small ionic radius, for alkali ions, which have a larger ionic radius.

[0022] The glass plate 21 is a flat plate in this embodiment, but may be a curved plate.

[0023] The thickness of the glass plate 21 is preferably 1.5 mm to 5.0 mm. If the thickness of the glass plate 21 is 1.5 mm or more, the glass plate 21 is less likely to break upon impact. The thickness of the glass plate 21 is more preferably 1.7 mm or more. On the other hand, if the thickness of the glass plate 21 is 5.0 mm or less, the cover glass 20 is thin and not bulky. The thickness of the glass plate 21 is more preferably 3.0 mm or less.

[0024] The flexural modulus of the glass plate 21 is preferably 500 MPa or more. If the flexural modulus of the glass plate 21 is 500 MPa or more, the glass plate 21 is less likely to break due to impact. The flexural modulus of the glass plate 21 is more preferably 30 GPa or more, and even more preferably 50 GPa or more. The flexural modulus of the glass plate 21 is more preferably 100 GPa or less.

[0025] The flexural modulus of the glass plate 21 governs the flexural modulus of the cover glass 20. Therefore, the flexural modulus of the cover glass 20 is preferably 500 MPa or more, more preferably 30 GPa or more, and even more preferably 50 GPa or more. Moreover, the flexural modulus of the glass plate 21 of the cover glass 20 is more preferably 100 GPa or less.

[0026] The resin film 22 is not particularly limited, but includes, for example, acrylic resin, epoxy resin, polyester resin, silicone resin, polycarbonate resin, polyurethane resin, polyurea resin, ethylene-vinyl acetate copolymer resin, resin modified from polyvinyl alcohol, cycloolefin polymer resin, polystyrene resin, fluororesin, polyamide resin, polyimide resin, polyamideimide resin, etc. An example of a resin modified from polyvinyl alcohol is polyvinyl butyral resin.

[0027] From the viewpoint of availability, the resin film 22 preferably contains at least one resin selected from the group consisting of polyimide resin, epoxy resin, polycycloolefin resin, polycarbonate resin, and acrylic resin. From the viewpoint of heat resistance, the resin film 22 more preferably contains polyimide resin.

[0028] The resin film 22 is obtained by applying a liquid resin composition to the inner surface 21a of the glass plate 21 using a spray coating method, inkjet method, or the like, and then solidifying it. Solidification includes curing. To strengthen the adhesion between the glass plate 21 and the resin film 22, a silane coupling agent may be applied to the inner surface 21a of the glass plate 21 in advance. Examples of the silane coupling agent that can be used include aminosilanes, epoxysilanes, vinylsilanes, γ-methacryloxypropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane. Examples of the aminosilane include γ-aminopropyltriethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-N'-β-(aminoethyl)-γ-aminopropyltriethoxysilane, and γ-anilinopropyltrimethoxysilane. Epoxy silanes include γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, etc. Vinyl silanes include vinyltrimethoxysilane, N-β-(N-vinylbenzylaminoethyl)-γ-aminopropyltrimethoxysilane, etc.

[0029] The resin film 22 may be applied to a substrate other than the glass plate 21, solidified, and then transferred from the substrate to the inner surface 21 a of the glass plate 21.

[0030] The resin film 22 is preferably in contact with the inner surface 21 a of the glass plate 21. This is because if the resin film 22 were not in contact with the inner surface 21 a of the glass plate 21 and an inorganic film (not shown) existed between the resin film 22 and the glass plate 21, cracks in the inorganic film (not shown) would extend to the glass plate 21. However, even if an inorganic film (not shown) exists between the resin film 22 and the glass plate 21, the resin film 22 can suppress the extension of cracks midway between the inorganic film 23 and the glass plate 21.

[0031] The resin film 22 is preferably in contact with the outer surface 23b of the inorganic film 23. Compared to when the resin film 22 is not in contact with the outer surface 23b of the inorganic film 23, the resin film 22 is closer to the source of the crack, and the propagation of the crack can be stopped before it expands.

[0032] The thickness of the resin film 22 is 0.01 μm to 5 μm. If the thickness of the resin film 22 is 0.01 μm or more, the resin film 22 can suppress the propagation of cracks. The thickness of the resin film 22 is preferably 0.10 μm or more, and more preferably 0.20 μm or more. On the other hand, if the thickness of the resin film 22 is 5 μm or less, the high temperature and humidity resistance and heat resistance are good, and perspective distortion is small. The thickness of the resin film 22 is preferably 4 μm or less, and more preferably 3 μm or less.

[0033] The thickness of the resin film 22 is measured at the center of the inner surface 21a of the glass plate 21. This is because large tensile stress occurs at the center of the inner surface 21a. The measurement sample is obtained by cutting the cover glass 20 along the line L1 shown in Figure 2. The line L1 is set so that the distance from the center 21a1 of the inner surface 21a to the peripheral edge 21a2 of the inner surface 21a is the shortest. This is because large tensile stress occurs at the center of this line L1. The cut surface of the measurement sample is observed with a scanning electron microscope (SEM), and the average film thickness within a range from the center 21a1 of the inner surface 21a to 10% of the distance D from the center 21a1 to the peripheral edge 21a2 is used as the film thickness.

[0034] The total thickness of the glass plate 21 and the resin film 22 is not particularly limited, but is preferably 1.5 mm to 5.0 mm. If the total thickness is 1.5 mm or more, the glass plate 21 is less likely to break upon impact. The total thickness is more preferably 1.7 mm or more. On the other hand, if the total thickness is 5.0 mm or less, the cover glass 20 is thin and not bulky. The total thickness is more preferably 3.0 mm or less. The total thickness is measured at the center of the inner surface 21a of the glass plate 21, similar to the film thickness of the resin film 22.

[0035] The arithmetic mean roughness Ra of the inner surface 22a of the resin film 22 is preferably 0.5 nm or more, more preferably 1.0 nm or more, and even more preferably 1.5 nm or more, from the viewpoint of adhesion between the resin film 22 and the inorganic film 23. The arithmetic mean roughness Ra is measured in accordance with JIS B0601:2013. The arithmetic mean roughness Ra of the inner surface 22a of the resin film 22 is preferably 100 nm or less, more preferably 90 nm or less, and even more preferably 80 nm or less.

[0036] The unevenness of the surface of the resin film 22 is transferred to the surface of the inorganic film 23, etc. The arithmetic mean roughness Ra of the inner surface 20a of the cover glass 20 is approximately equal to the arithmetic mean roughness Ra of the inner surface 22a of the resin film 22. Therefore, the arithmetic mean roughness Ra of the inner surface 20a of the cover glass 20 is preferably 0.5 nm or more, more preferably 1.0 nm or more, and even more preferably 1.5 nm or more. The arithmetic mean roughness Ra of the inner surface 20a of the cover glass 20 is preferably 100 nm or less, more preferably 90 nm or less, and even more preferably 80 nm or less.

[0037] The inorganic film 23 is preferably a dielectric multilayer film. The dielectric multilayer film includes two or more dielectric films with different refractive indices. For example, the dielectric multilayer film includes two or more films selected from a low refractive index dielectric film (low refractive index film), a medium refractive index dielectric film (medium refractive index film), and a high refractive index dielectric film (high refractive index film). The dielectric multilayer film can increase or decrease the reflectance by utilizing the interference effect of light. The higher the reflectance, the lower the transmittance. The transmittance also depends on the extinction coefficient, which is determined by the type of material. The higher the extinction coefficient, the higher the absorption rate and the lower the transmittance.

[0038] Examples of materials for the high-refractive-index film include silicon (Si). When the cover glass 20 is an infrared pass filter, amorphous silicon is preferred from the viewpoint of its visible light absorption ability, and amorphous silicon not doped with hydrogen is particularly preferred. The high-refractive-index film preferably has a refractive index of 3.0 or more, more preferably 4.0 or more.

[0039] The material of the medium refractive index film is, for example, Ta. ２ O５ , Nb ２ O ５ , TiO ２ , ZrO ２ , HfO ２ , SiO, Al ２ O ３ When the cover glass 20 is an infrared pass filter, Nb is used in view of the ease of designing a film that suppresses reflection of light with a high incident angle and the high reproducibility of the optical constants. ２ O ５ and Ta ２ O ５ The refractive index of the medium refractive index film is preferably 1.6 to 3.0, and more preferably 1.8 to 2.5.

[0040] The low refractive index film may be made of, for example, SiO ２ , SiO ｘ N ｙ , SiO, SiN, Al ２ O ３ Among them, from the viewpoint of productivity, SiO ２ The low refractive index film preferably has a refractive index of 2.0 or less, more preferably 1.5 or less.

[0041] The total number of layers in the dielectric multilayer film is preferably 10 or more, more preferably 15 or more, and even more preferably 20 or more, in order to obtain the desired optical characteristics. However, if the total number of layers is too large, warping or the like may occur, or the film thickness may increase. Therefore, the total number of layers is preferably 70 or less, more preferably 60 or less, and even more preferably 50 or less.

[0042] From the viewpoint of productivity, the thickness of the dielectric multilayer film is preferably 1.5 μm or less, and more preferably 2.0 μm or less.

[0043] The dielectric multilayer film may be formed by either a dry method or a wet method. Dry methods include, for example, CVD, sputtering, or vacuum deposition. Wet methods include, for example, spraying, inkjet printing, or dipping.

[0044] The dielectric multilayer film preferably has an anti-reflection function for light of a desired wavelength. The dielectric multilayer film is in contact with air and prevents reflection of infrared rays at the interface between the air and the cover glass 20. The dielectric multilayer film prevents reflection of light traveling from the inside to the outside of the cover glass 20, for example. For example, when the cover glass 20 is an infrared pass filter, the dielectric multilayer film has an anti-reflection function for infrared rays, and the cover glass 20 has a maximum transmittance T ８００－１６００ＭＡＸ is preferably 90% to 100%. ８００－１６００ＭＡＸ is more preferably 93% or more, and even more preferably 95% or more. ８００－１６００ＭＡＸ is more preferably 99% or less, and even more preferably 98% or less.

[0045] The dielectric multilayer film preferably has a light-blocking function for light of a desired wavelength. For example, when the cover glass 20 is an infrared pass filter, the dielectric multilayer film has a light-blocking function for visible light, and the cover glass 20 has an average transmittance T ４００－６８０ＡＶＥ is preferably 0% to 5%. ４００－６８０ＡＶＥ is more preferably 3% or less, and even more preferably 1% or less.

[0046] It is preferable that the dielectric multilayer film has an anti-reflection function for light of a desired wavelength and a light-blocking function for light of another wavelength. For example, when the cover glass 20 is an infrared pass filter, it is preferable that the dielectric multilayer film has an anti-reflection function for infrared rays and a light-blocking function for visible light. In addition, the T of the cover glass 20 ８００－１６００ＭＡＸ and T ４００－６８０ＡＶＥ is preferably in the above range.

[0047] As shown in Figure 1, the cover glass 20 preferably has a second inorganic film 24 on the opposite side of the glass plate 21 from the inorganic film 23. The second inorganic film 24 improves the optical properties of the cover glass 20, similar to the inorganic film 23. When an impact is applied to the cover glass 20 from the outside, compressive stress is generated in the second inorganic film 24, but tensile stress is not generated. Therefore, the second inorganic film 24 is unlikely to break, and a resin film may not be required between the second inorganic film 24 and the glass plate 21. However, a resin film may be present between the second inorganic film 24 and the glass plate 21.

[0048] The second inorganic film 24 is preferably a dielectric multilayer film, similar to the inorganic film 23. The dielectric multilayer film preferably has an anti-reflection function for light of a desired wavelength, a light-blocking function for light of a desired wavelength, or an anti-reflection function for light of a desired wavelength and a light-blocking function for light of another wavelength. For example, if the cover glass 20 is an infrared pass filter, the dielectric multilayer film preferably has an anti-reflection function for infrared light and a light-blocking function for visible light.

[0049] The inorganic film 23 and the second inorganic film 24 may have different functions. For example, the inorganic film 23 may have an anti-reflection function for light of a desired wavelength (e.g., infrared light), and the second inorganic film 24 may have a light-blocking function for light of another wavelength (e.g., visible light). Alternatively, the inorganic film 23 may have a light-blocking function for light of a desired wavelength (e.g., visible light), and the second inorganic film 24 may have an anti-reflection function for light of another wavelength (e.g., infrared light).

[0050] As shown in Fig. 1, the cover glass 20 preferably has a water-repellent film 25 on the outer surface 20b. The water-repellent film 25 prevents water droplets and the like from adhering to the outer surface 20b of the cover glass 20 and suppresses absorption of infrared rays by the water droplets. In this embodiment, the water-repellent film 25 is formed on the second inorganic film 24, but the second inorganic film 24 may be omitted and the water-repellent film 25 may be formed on the glass plate 21. The water-repellent film 25 may have any configuration.

[0051] Next, a cover glass 20 according to a modified example will be described with reference to Figures 3 and 4. Differences from the above embodiment will be mainly described below. As shown in Figure 3, the resin film 22 of this modified example is formed over the entire inner surface 21a of the glass plate 21, and extends continuously from the entire periphery of the inner surface 21a to the side surface 21c, covering the corners of the inner surface 21a and the side surface 21c of the glass plate 21. The resin film 22 can prevent cracks in the inorganic film 23 from extending to the glass plate 21 at the corners. Furthermore, after the resin film 22 is formed, the corners of the glass plate 21 are less likely to be scratched.

[0052] The resin film 22 preferably covers less than 50% of the entire side surface of the glass plate 21. In other words, the resin film 22 preferably does not cover more than 50% of the entire side surface of the glass plate 21. When the glass plate 21 is a rectangular plate, the entire side surface of the glass plate 21 means the four side surfaces 21c. If most of the side surfaces 21c are not covered with the resin film 22, the adhesion between the glass plate 21 and the housing 40 is good.

[0053] Experimental data will be described below. In Examples 1 to 5 below, cover glasses 20 were fabricated with the same configuration except for the film thickness of the resin film 22, as shown in Table 1. In Example 1, a cover glass 20 was fabricated that had, from the outside to the inside, a second inorganic film 24, a glass plate 21, and an inorganic film 23, in this order. On the other hand, in Examples 2 to 5, a cover glass 20 was fabricated that had, from the outside to the inside, a second inorganic film 24, a glass plate 21, a resin film 22, and an inorganic film 23, in this order. Examples 1 and 5 are comparative examples, and Examples 2 to 4 are working examples.

[0054] In Examples 1 to 5, the glass plate 21 was a rectangular plate (length: 33 mm, width: 33 mm, thickness: 2 mm). The glass plate 21 was chemically strengthened glass (maximum compressive stress of the surface: 900 MPa). The flexural modulus of the glass plate 21 was 73 GPa.

[0055] In Examples 1 to 5, the inorganic film 23 and the second inorganic film 24 both had an anti-reflection function for infrared rays and a light-shielding function for visible light. The inorganic film 23 was a dielectric multilayer film, and was made of SiO ２ layer and Nb ２ O ５The second inorganic film 24 is a dielectric multilayer film, and is composed of an amorphous Si layer and a SiO ２ layer and Nb ２ O ５ The layer was repeated multiple times.

[0056] In Examples 2 to 5, the resin film 22 was formed by spray coating on the entire inner surface 21a of the glass plate 21 and on the corners between the inner surface 21a and the side surface 21c. In other words, the resin film 22 covered not only the entire inner surface 21a but also the corners between the inner surface 21a and the side surface 21c. The resin film 22 contained a polyimide resin.

[0057]

[0058] Impact resistance was investigated using a test apparatus 100 shown in FIG. 5 . The test apparatus 100 includes a square frame 101 and an iron ball 102. The square frame 101 horizontally supports the cover glass 20 from below. The upper surface of the cover glass 20 is the outer surface 20b, and the lower surface of the cover glass 20 is the inner surface 20a. An area of ​​the inner surface 20a within a distance of 2 mm from the periphery of the inner surface 20a contacted the square frame 101. The iron ball 102 was dropped freely from a height of 300 mm onto the center of the upper surface of the cover glass 20. The weight of the iron ball 102 was 0.5 kg. In Table 1, an impact resistance rating of "A" means that the cover glass 20 did not break, and an impact resistance rating of "B" means that the cover glass 20 broke.

[0059] The transmitted wavefront aberration was measured in the central region of the inner surface 21a of the glass plate 21. The central region refers to the entire area of ​​the inner surface 21a, excluding the area within 2 mm from the periphery. A Shack-Hartmann sensor (manufactured by Imagine Optic, product name: HASO4) was used as the measuring device. In Table 1, a transmitted wavefront aberration of "A" means that the RMS value of the transmitted wavefront aberration was 63.3 nm or less, and a transmitted wavefront aberration of "B" means that the RMS value of the transmitted wavefront aberration exceeded 63.3 nm. The smaller the RMS value of the transmitted wavefront aberration, the smaller the perspective distortion.

[0060] The high-temperature, high-humidity resistance was investigated by exposing the cover glass 20 to an environment of 85° C. and 85% relative humidity for 1,000 hours using a high-temperature, high-humidity chamber. In Table 1, a high-temperature, high-humidity resistance rating of "A" means that the inorganic film 23 did not peel off from the glass plate 21, and a high-temperature, high-humidity resistance rating of "B" means that the inorganic film 23 peeled off from the glass plate 21.

[0061] The heat resistance was investigated by exposing the cover glass 20 to an environment at a temperature of 150° C. for 1 hour using a high-temperature bath. In Table 1, a heat resistance rating of "A" means that the inorganic film 23 did not peel off from the glass plate 21, and a heat resistance rating of "B" means that the inorganic film 23 peeled off from the glass plate 21.

[0062] T ８００－１６００ＭＡＸ and T ４００－６８０ＡＶＥ was measured using a spectrophotometer (manufactured by JASCO Corporation, product name: V-7200). The angle of incidence of light on the cover glass 20 was set to 0°.

[0063] As can be seen from Table 1, in Examples 2 to 4, unlike Examples 1 and 5, the film thickness of the resin film 22 was 0.01 μm to 5 μm, so the impact resistance, high temperature and humidity resistance, and heat resistance were good, and the perspective distortion was small.

[0064] The cover glass and optical device according to the present disclosure have been described above, but the present disclosure is not limited to the above-described embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations are possible within the scope of the claims. These naturally fall within the technical scope of the present disclosure.

[0065] This application claims priority based on Japanese Patent Application No. 2024-101928, filed June 25, 2024, the disclosure of which is incorporated herein in its entirety by reference.

[0066] REFERENCE SIGNS LIST 10 Optical device 20 Cover glass 20a Inner surface 20b Outer surface 21 Glass plate 22 Resin film 23 Inorganic film 30 Electronic device

Claims

1. A cover glass for protecting an electronic device, the cover glass having an inner surface facing the electronic device and an outer surface facing opposite the inner surface, and having, from the outside to the inside, a glass plate, a resin film, and an inorganic film in this order, the resin film having a film thickness of 0.01 μm to 5 μm.

2. The cover glass according to claim 1, wherein the inorganic film is a dielectric multilayer film having an anti-reflection function for light of a desired wavelength.

3. The cover glass according to claim 2, wherein the dielectric multilayer film has an anti-reflection function against infrared rays, and the cover glass has a maximum transmittance of 90% to 100% for light wavelengths of 800 nm to 1600 nm.

4. The cover glass according to claim 1, wherein the inorganic film is a dielectric multilayer film having a light-blocking function against light of a desired wavelength.

5. The cover glass according to claim 4, wherein the dielectric multilayer film has a light-blocking function against visible light, and the cover glass has an average transmittance of 0% to 5% for light wavelengths of 400 nm to 680 nm.

6. The cover glass according to claim 1, wherein the inorganic film is a dielectric multilayer film having an anti-reflection function for light of a desired wavelength and a light-blocking function for light of another wavelength.

7. The cover glass according to claim 6, wherein the dielectric multilayer film has an anti-reflection function for infrared rays and a light-blocking function for visible light, and the cover glass has a maximum transmittance of 90% to 100% for light wavelengths of 800 nm to 1600 nm and an average transmittance of 0% to 5% for light wavelengths of 400 nm to 680 nm.

8. The cover glass of claim 1, wherein the cover glass has a flexural modulus of elasticity of 500 MPa to 100 GPa.

9. The cover glass according to claim 1, wherein the resin film contains at least one resin selected from the group consisting of polyimide resin, epoxy resin, polycycloolefin resin, polycarbonate resin, and acrylic resin.

10. The cover glass of claim 1, wherein the resin film comprises a polyimide resin.

11. The cover glass according to claim 1, wherein the total thickness of the glass plate and the resin film is 1.5 mm to 5.0 mm.

12. The cover glass of claim 1, wherein the glass plate is chemically strengthened glass.

13. The cover glass of claim 1, wherein the inner surface of the cover glass has an arithmetic mean roughness Ra of 0.5 nm to 100 nm.

14. The cover glass according to claim 1, wherein the resin film is formed on the entire inner surface of the glass plate, and extends continuously from the entire periphery of the inner surface of the glass plate to the side surface of the glass plate, covering the corners of the inner surface and side surface of the glass plate.

15. The cover glass according to claim 14, wherein the resin film covers less than 50% of the entire side surface of the glass plate.

16. An optical device comprising the cover glass according to any one of claims 1 to 15 and the electronic device.

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