Diffusion plate, diffusion plate manufacturing method, and projection device

Abstract

This diffusion plate is provided with: a glass substrate having a first main surface and a second main surface facing the opposite direction from the first main surface; and a lens array formed on the first main surface of the glass substrate. When the first main surface of the glass substrate is viewed from the front side, the glass substrate and the lens array each have a ring shape, and the lens array includes a plurality of lenses. The first main surface of the glass substrate has an annular flat surface having a width of 1.0 mm or more between the inner periphery of the glass substrate and the inner periphery of the lens array, or has an annular flat surface having a width of 1.0 mm or more between the outer periphery of the glass substrate and the outer periphery of the lens array.

Description

Technical Field

[0001] The present disclosure relates to a diffusion plate, a method for manufacturing the diffusion plate, and a projection device. Background Art

[0002] As a method for manufacturing a diffuser plate, there is a method of sandblasting one side of a glass substrate. Patent Documents 1 and 2 disclose a diffuser plate comprising a glass substrate, wherein a lens array is formed on at least one side of the glass substrate. It is generally known that a diffuser plate formed with a lens array has better light distribution controllability than a diffuser plate formed by sandblasting. The lens array has a plurality of lenses. To form the lens array, at least one method selected from wet etching, dry etching, cutting, and laser processing is used, for example.

[0003] Patent Document 1: International Publication No. 2014 / 104106

[0004] Patent Document 2: International Publication No. 2019 / 189225

[0005] It is conceivable that when the main surface of the glass substrate is viewed from the front, the glass substrate and the lens array each have a ring-shaped diffusion plate. A through hole is formed in the center of the glass substrate, and the rotation shaft is embedded in the through hole.

[0006] If a lens array is formed on the entire main surface of a glass substrate having a ring shape, the presence of the lenses may cause excessive stress concentration on the inner or outer periphery of the glass substrate, potentially causing cracks in the glass substrate. Summary of the Invention

[0007] One aspect of the present disclosure provides a technique for improving the strength of a diffuser plate.

[0008] A diffuser plate according to one embodiment of the present disclosure comprises: a glass substrate having a first main surface and a second main surface facing oppositely to the first main surface; and a lens array formed on the first main surface of the glass substrate. When the first main surface of the glass substrate is observed from the front, the glass substrate and the lens array each have a ring-shaped shape, and the lens array includes a plurality of lenses. The first main surface of the glass substrate has a flat annular surface with a width of 1.0 mm or more between the inner periphery of the glass substrate and the inner periphery of the lens array, or has a flat annular surface with a width of 1.0 mm or more between the outer periphery of the glass substrate and the outer periphery of the lens array.

[0009] According to one embodiment of the present disclosure, an annular flat surface having a width of 1.0 mm or greater is provided along the inner or outer periphery of the first main surface. This can suppress excessive stress concentration and improve the strength of the diffuser plate. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a top view of a diffuser plate according to one embodiment.

[0011] Figure 2 It is along Figure 1 Cross-sectional view along line II-II.

[0012] Figure 3 It means composition Figure 1 A top view of an example of an arrangement of lenses of a lens array.

[0013] Figure 4 Yes means including Figure 1 A cross-sectional view of an example of a diffuser plate for a projection device.

[0014] Figure 5 This is a flowchart showing a method for manufacturing a diffuser plate according to one embodiment.

[0015] Figure 6 Yes Figure 5 A cross-sectional view of an example of S101.

[0016] Figure 7 Yes Figure 5 A cross-sectional view of an example of S102.

[0017] Figure 8 Yes Figure 5 A cross-sectional view of an example of S103.

[0018] Figure 9 Yes Figure 5 A cross-sectional view of an example of S104.

[0019] Figure 10 This is a cross-sectional view showing an example of a method for measuring the fracture strength of a diffuser plate.

[0020] Figure 11 It is a box graph showing the measurement results of the fracture strength of the diffuser plates according to Examples 1 to 3. DETAILED DESCRIPTION

[0021] Hereinafter, the method for implementing the present disclosure will be described with reference to the accompanying drawings. In each of the drawings, the same or corresponding structures are marked with the same reference numerals, and the description is sometimes omitted. In the specification, the "to" indicating a numerical range means that the numerical values ​​recorded before and after it are included as the lower limit and the upper limit.

[0022] Reference Figures 1 to 4 , a diffuser plate 2 according to an embodiment will be described. Figures 1 to 4As shown, the diffuser plate 2 includes a glass substrate 10 and a lens array 20. The glass substrate 10 has a first principal surface 11 and a second principal surface 12 facing opposite to the first principal surface 11. The lens array 20 is formed on the first principal surface 11 of the glass substrate 10.

[0023] The lens array 20 is formed on the first principal surface 11 of the glass substrate 10, but not on the second principal surface 12 of the glass substrate 10. The second principal surface 12 of the glass substrate 10 is a flat surface as a whole. However, the lens array 20 may be formed not only on the first principal surface 11 of the glass substrate 10, but also on the second principal surface 12 of the glass substrate 10.

[0024] like Figure 1 As shown in FIG, when the first main surface 11 of the glass substrate 10 is viewed from the front, the glass substrate 10 and the lens array 20 each have a ring shape. Figure 1 In FIG, the area of ​​the dot pattern is the area of ​​the lens array 20. Figure 2 as well as Figure 3 As shown, the lens array 20 includes a plurality of lenses 21 .

[0025] like Figure 2 As shown, the glass substrate 10 may also have an inner peripheral surface 13 perpendicular to the first main surface 11 and the second main surface 12. In addition, the glass substrate 10 may also have chamfered surfaces 14 at the boundaries between the inner peripheral surface 13 and the first main surface 11 and at the boundaries between the inner peripheral surface 13 and the second main surface 12. Although the chamfered surfaces 14 are C-chamfered surfaces in this embodiment, they may also be R-chamfered surfaces.

[0026] The glass substrate 10 may also have an outer peripheral surface 15 perpendicular to the first principal surface 11 and the second principal surface 12. Furthermore, the glass substrate 10 may also have chamfered surfaces 16 at the boundaries between the outer peripheral surface 15 and the first principal surface 11, and at the boundaries between the outer peripheral surface 15 and the second principal surface 12. In this embodiment, the chamfered surfaces 16 are C-chamfered surfaces, but they may also be R-chamfered surfaces.

[0027] The inner diameter D1 of the glass substrate 10 (see Figure 1 ) is preferably 5mm to 20mm, more preferably 7mm to 15mm.

[0028] The outer diameter D2 of the glass substrate 10 (see Figure 1 ) is preferably 20mm to 100mm, more preferably 25mm to 60mm.

[0029] The thickness T of the glass substrate 10 (see Figure 2 ) is preferably 0.2mm to 2.0mm, more preferably 0.5mm to 1.0mm.

[0030] The first main surface 11 of the glass substrate 10 has an annular first flat surface 17 along the inner circumference of the glass substrate 10, or has an annular second flat surface 18 along the outer circumference of the glass substrate 10. Although the first main surface 11 has both the first flat surface 17 and the second flat surface 18 in this embodiment, it may have only one of them.

[0031] like Figure 1 As shown, the first flat surface 17 is formed between the inner periphery of the glass substrate 10 and the inner periphery of the lens array 20. The inner periphery of the lens array 20 is provided outside the inner periphery of the glass substrate 10 and is concentric with the inner periphery of the glass substrate 10. The inner periphery of the lens array 20 is the smallest imaginary circle that is tangent to the plurality of lenses 21.

[0032] The width W1 of the first flat surface 17 (see Figure 2 ), for example, 1.0 mm or greater. When the width W1 is 1.0 mm or greater, the distance between the inner periphery of the glass substrate 10 and the lens 21 is sufficiently large, thereby suppressing excessive stress concentration on the inner periphery of the glass substrate 10 due to the presence of the lens 21. This prevents cracks from extending from the inner periphery of the glass substrate 10, thereby preventing the glass substrate 10 from breaking.

[0033] The width W1 of the first flat surface 17 is preferably 2.5 mm or more. The larger the width W1, the greater the strength of the glass substrate 10. However, from the perspective of miniaturization of the diffuser plate 2, the width W1 is preferably 30 mm or less.

[0034] like Figure 1 As shown, the second flat surface 18 is formed between the outer periphery of the glass substrate 10 and the outer periphery of the lens array 20. The outer periphery of the lens array 20 is provided concentrically with the outer periphery of the glass substrate 10 on the inner side of the outer periphery of the glass substrate 10. The outer periphery of the lens array 20 is the largest imaginary circle tangent to the plurality of lenses 21.

[0035] The width W2 of the second flat surface 18 (see Figure 2 ), for example, 1.0 mm or greater. When the width W2 is 1.0 mm or greater, the distance between the periphery of the glass substrate 10 and the lens 21 is sufficiently large, which can suppress the occurrence of excessive stress concentration on the periphery of the glass substrate 10 due to the presence of the lens 21. This can suppress the extension of cracks from the periphery of the glass substrate 10, and can prevent the glass substrate 10 from breaking.

[0036] The width W2 of the second flat surface 18 is preferably 2.5 mm or more. The larger the width W2, the greater the strength of the glass substrate 10. However, from the perspective of miniaturization of the diffuser plate 2, the width W2 is preferably 10 mm or less.

[0037] The material of the glass substrate 10 is not particularly limited, but examples thereof include aluminosilicate glass, borosilicate glass, and quartz glass.

[0038] like Figure 2 as well as Figure 3 As shown, the lens array 20 includes a plurality of lenses 21. In this embodiment, the lenses 21 are concave lenses, but they may also be convex lenses. Furthermore, in this embodiment, the lenses 21 are spherical lenses, but they may also be aspherical lenses. The lens array 20 refracts and diffuses light that passes through the diffuser plate 2.

[0039] The plurality of lenses 21 have substantially the same shape and substantially the same size and are regularly arranged. Figure 3 As shown in FIG. 1 , when the first main surface 11 of the glass substrate 10 is viewed from the front, the centers of the lenses 21 are arranged at the lattice points of a regular hexagon (six vertices and one center of a regular hexagon). Figure 3 In , grayscale represents the difference between height and depth. The closer the color of the image is from white to black, the lower the height is. Figure 3 In FIG, a dotted line represents a straight line connecting two adjacent vertices of a regular hexagon.

[0040] In addition, the arrangement of the lenses 21 is not limited to Figure 3 The arrangement shown. For example, the center of the lens 21 may be arranged at the lattice points of a square lattice (the four vertices of a square) instead of the center of the lens 21 being arranged at the lattice points of a regular hexagonal lattice. In addition, the center of the lens 21 may be arranged at the lattice points of a lattice formed by compressing a regular hexagonal lattice or a square lattice in a prescribed direction. Furthermore, the arrangement of the lenses 21 may be irregular or non-regular. In addition, the height difference of the lens 21 may be the same or different among multiple lenses 21.

[0041] When observing the first main surface 11 of the glass substrate 10 from the front, each lens 21 has a hexagonal shape. In this case, the circular equivalent diameter of each lens 21 is preferably 30 μm to 500 μm, and more preferably 110 μm to 300 μm. In addition, the height difference between the periphery and the center of each lens 21 is preferably 3 μm to 50 μm. In addition, although the shape of the lens 21 is hexagonal in this embodiment, it is not limited to hexagonal, and it can also be circular, elliptical, or polygonal. In addition, although there is no flat surface between adjacent lenses 21 in this embodiment, there can also be a flat surface.

[0042] like Figure 4As shown, the diffuser plate 2 is mounted on, for example, a projection device (projector) 1. The projection device 1 is not particularly limited, but is, for example, a head-up display (HUD). The diffuser plate 2 transmits light emitted from the light source 3. The transmitted light is diffused by the lens array 20. This suppresses glare.

[0043] Projection device 1, for example, includes a diffuser plate 2 and a light source 3. Light source 3 may include, for example, a laser light source. Laser light sources offer excellent brightness and color rendering, but they also increase glare. When light source 3 includes a laser light source, the diffuser plate 2 significantly reduces glare. Light source 3 may include multiple types of laser light sources, such as a blue laser light source, a green laser light source, and a red laser light source.

[0044] Projection device 1 includes a rotating shaft 5 and a rotating motor 6. The rotating shaft 5 is embedded in a through-hole 19 in the center of a glass substrate 10. The rotating motor 6 rotates the diffuser plate 2 together with the rotating shaft 5. Light emitted from the light source 3 passes through the diffuser plate 2 at a predetermined distance from the rotation centerline of the rotating shaft 5. Even if the lenses 21 are regularly arranged, rotating the diffuser plate 2 together with the rotating shaft 5 can suppress glare.

[0045] When the entire second principal surface 12 of the glass substrate 10 is flat, the first principal surface 11 of the glass substrate 10 is preferably arranged to face the light source 3. The unevenness of the lens array 20 can suppress reflection of light incident from the light source 3 to the diffuser plate 2. This can reduce the reflectivity of light and increase the transmittance of light.

[0046] Reference Figures 5 to 9 , a method for manufacturing the diffuser plate 2 according to one embodiment will be described. Figure 5 As shown, the method for manufacturing the diffuser plate 2 includes, for example, steps S101 to S104. Furthermore, the method for manufacturing the diffuser plate 2 may include steps other than steps S101 to S104. For example, after step S104, a step of chamfering the inner and outer peripheries of the glass substrate 10, i.e., forming the chamfered surfaces 14 and 16, may be performed. Furthermore, before step S104, a step of heating the entire glass substrate 10 may be performed to reduce stress remaining in the glass substrate 10 due to laser processing.

[0047] Step S101 includes: Figure 6As shown, the first laser beam LB1 is irradiated on the first principal surface 11 of the glass substrate 10 at predetermined positions where lenses 21 are to be formed, thereby forming recesses 22. The recesses 22 are formed at the positions irradiated by the first laser beam LB1. Step S101 forms a plurality of recesses 22 by changing the irradiation position of the first laser beam LB1 on the first principal surface 11 of the glass substrate 10. In this embodiment, the irradiation position of the first laser beam LB1 is changed by moving the glass substrate 10. However, this can also be achieved by moving an optical element (e.g., a reflective mirror) constituting the optical system 52.

[0048] The first laser beam LB1 forms the recess 22 by sublimating or evaporating the glass. The shape and size of the recess 22 are controlled by the focusing position, focusing angle, focusing diameter, and irradiation time of the first laser beam LB1. Compared to sandblasting, laser processing can reduce damage to the glass substrate 10 (e.g., the occurrence of potential damage) and improve the strength of the diffuser plate 2. Furthermore, compared to sandblasting, laser processing makes it easier to control the position, shape, and size of the recess 22.

[0049] As described above, first laser beam LB1 forms recess 22 by sublimating or evaporating glass. Therefore, from the perspective of glass absorptivity, the wavelength of first laser beam LB1 is preferably 9.2 μm to 10.8 μm. From the perspective of glass absorptivity, light source 51 of first laser beam LB1 is preferably a CO2 laser. Light source 51 is, for example, a continuous wave laser.

[0050] Immediately after being emitted from light source 51, first laser beam LB1 is linearly polarized, and the intensity distribution of the cross section of first laser beam LB1 is Gaussian. An optical system 52 is provided between light source 51 and glass substrate 10. Optical system 52 directs the first laser beam LB1 emitted from light source 51 toward glass substrate 10. First laser beam LB1 is incident perpendicularly to first principal surface 11 of glass substrate 10. Optical system 52 includes, for example, a wavelength plate 53 and a focusing lens 54.

[0051] Wave plate 53 converts the polarization of first laser beam LB1 from linearly polarized light to circularly polarized light. Wave plate 53 is formed, for example, by a quarter-wave plate. Wave plate 53 is disposed, for example, between light source 51 and focusing lens 54. Wave plate 53 may be omitted, and optical system 52 may irradiate glass substrate 10 with linearly polarized first laser beam LB1.

[0052] The condenser lens 54 condenses the first laser beam LB1 onto the glass substrate 10. The condenser lens 54 irradiates the glass substrate 10 with the first laser beam LB1. The condenser lens 54 is located, for example, at or near the first principal surface 11 of the glass substrate 10. The glass substrate 10 is locally heated, and the heated portion is removed, thereby forming the recess 22. The condenser lens 54 is disposed, for example, between the wave plate 53 and the glass substrate 10.

[0053] Furthermore, the optical system 52 may include a homogenizer. The homogenizer converts the intensity distribution of the cross section of the first laser beam LB1 from a Gaussian distribution to a top-hat distribution. The homogenizer is disposed, for example, between the wave plate 53 and the condenser lens 54.

[0054] The optical system 52 may also include an aperture. The aperture has a circular opening smaller than the cross-section of the first laser beam LB1. By shielding the peripheral edge of the cross-section of the first laser beam LB1, the circularity of the cross-section of the first laser beam LB1 is improved. The aperture is, for example, disposed between the wave plate 53 and the focusing lens 54. Alternatively, the aperture is, for example, disposed between the homogenizer and the focusing lens 54.

[0055] Prior to step S101, various functional films may be formed on the glass substrate 10. For example, a protective film may be formed on at least one of the first principal surface 11 and the second principal surface 12 of the glass substrate 10. The protective film prevents the adhesion of machining debris scattered from the first principal surface 11 by irradiation with the first laser beam LB1. The protective film is preferably a removable film, such as a water-soluble film.

[0056] Step S102 includes: Figure 7 As shown, the second laser beam LB2 is irradiated at a predetermined position on the inner periphery of the glass substrate 10 to form a first modified layer 31. The first modified layer 31 is formed, for example, in a linear shape from the first main surface 11 to a predetermined depth, and also in a linear shape from the second main surface 12 to a predetermined depth. Although not shown, the first modified layer 31 may also be formed over the entire thickness direction of the glass substrate 10.

[0057] Step S102 includes repeatedly rotating the glass substrate 10 and irradiating the second laser beam LB2 at a position at a predetermined distance from the rotation center line of the glass substrate 10. The distance between the optical axis of the second laser beam LB2 and the rotation center line of the glass substrate 10 is equal to half the inner diameter D1 of the glass substrate 10. In addition, although in this embodiment, the irradiation position of the second laser beam LB2 is changed by moving the glass substrate 10 (more specifically, rotating it), it can also be changed by moving an optical element (e.g., a reflective mirror) constituting the optical system 62.

[0058] The second laser beam LB2 modifies the glass to form the first modified layer 31. Two-photon absorption occurs where the second laser beam LB2 is focused, causing interaction between the second laser beam LB2 and the glass. This changes the physical properties of the glass (e.g., density), thereby forming the first modified layer 31. The shape and size of the first modified layer 31 are controlled by the focusing position, focusing angle, focusing diameter, and irradiation time of the second laser beam LB2.

[0059] As described above, the second laser beam LB2 forms the first modified layer 31 by modifying the glass. Therefore, the wavelength of the second laser beam LB2 is preferably 1000 nm to 1100 nm. The light source 61 of the second laser beam LB2 is, for example, a YAG laser. The light source 61 may also be a light source that oscillates a second high-frequency wave or a third harmonic. The light source 61 is, for example, a pulsed laser. The pulse width (the duration of each pulse) is, for example, 100 fs (femtoseconds) to 20 ps (picoseconds).

[0060] An optical system 62 is provided between the light source 61 and the glass substrate 10. The optical system 62 irradiates the glass substrate 10 with the second laser beam LB2 emitted from the light source 61. The second laser beam LB2 is incident perpendicularly to the first principal surface 11 or the second principal surface 12 of the glass substrate 10. The optical system 62 includes, for example, a wavelength plate 63, a focusing lens 64, and the like. Since the optical system 62 has the same configuration as the optical system 52, its description will be omitted.

[0061] Step S103 has: Figure 8 As shown, the third laser beam LB3 is irradiated to a predetermined position on the periphery of the glass substrate 10 to form a second modified layer 32. The second modified layer 32 is formed, for example, in a linear shape from the first main surface 11 to a predetermined depth, and also in a linear shape from the second main surface 12 to a predetermined depth. Although not shown, the second modified layer 32 may also be formed over the entire thickness direction of the glass substrate 10.

[0062] Step S103 includes repeatedly rotating the glass substrate 10 and irradiating the glass substrate 10 with the third laser beam LB3 at a position a certain distance from the rotation centerline of the glass substrate 10. The distance between the optical axis of the third laser beam LB3 and the rotation centerline of the glass substrate 10 is equal to half the outer diameter D2 of the glass substrate 10. In addition, although in this embodiment, the irradiation position of the third laser beam LB3 is changed by moving the glass substrate 10 (more specifically, rotating it), it can also be changed by moving an optical element (e.g., a reflective mirror) constituting the optical system 72.

[0063] The third laser beam LB3, like the second laser beam LB2, modifies the glass to form the second modified layer 32. Since the light source 71 of the third laser beam LB3 is configured similarly to the light source 61 of the second laser beam LB2, its description is omitted.

[0064] An optical system 72 is provided between the light source 71 and the glass substrate 10. The optical system 72 irradiates the glass substrate 10 with the third laser beam LB3 emitted from the light source 71. The third laser beam LB3 is incident perpendicularly to the first principal surface 11 or the second principal surface 12 of the glass substrate 10. The optical system 72 includes, for example, a wavelength plate 73, a focusing lens 74, and the like. Since the optical system 72 has the same configuration as the optical system 52, its description will be omitted.

[0065] The order of steps S101, S102, and S103 is not particularly limited. For example, S101 may be performed after S102 and S103. Furthermore, S103 and S104 may be performed in parallel. Specifically, after forming the first modified layer 31 and the second modified layer 32 on one surface of the glass substrate 10, the first modified layer 31 and the second modified layer 32 may be formed on the opposite surface of the glass substrate 10.

[0066] Step S104 includes: wet etching the glass substrate 10 on which the recess 22, the first modified layer 31, and the second modified layer 32 are formed. Figure 9 The lens array 20, the inner periphery of the glass substrate 10, and the outer periphery of the glass substrate 10 are formed simultaneously. The etching solution is selected according to the material of the glass substrate 10, but is, for example, a mixed acid of hydrofluoric acid (HF) and hydrochloric acid (HCl). Step S104 includes, for example, immersing the glass substrate 10 in the etching solution.

[0067] The lens 21 is formed by etching the recessed portion 22. In this case, a concave lens is formed as the lens 21. The first modified layer 31 and the second modified layer 32 are easier to etch than before modification and are selectively etched. Compared to cutting, wet etching can suppress damage to the glass substrate 10 (e.g., the occurrence of latent damage), thereby increasing the strength of the diffuser plate 2.

[0068] Example

[0069] The following describes experimental data. Examples 1 to 4 are examples, and Example 4 is a comparative example.

[0070] [Example 1]

[0071] In Example 1, by Figure 5 The manufacturing method shown produces Figures 1 to 3The diffuser plate 2 shown in FIG. As the glass substrate 10, "Dragontrail (registered trademark) Pro" (aluminosilicate glass) manufactured by AGC Corporation was prepared. The thickness of the glass substrate 10 was 1.1 mm.

[0072] Figure 5 The conditions of step S101 are as follows.

[0073] Light source: CO2 laser,

[0074] Wavelength: 9.6μm,

[0075] Spot angle: about 20°.

[0076] The recesses 22 are formed only on the first principal surface 11 of the glass substrate 10, not on the second principal surface 12. The recesses 22 are regularly arranged in the predetermined area (circular shape, inner diameter: 11 mm, outer diameter: 27 mm) where the lens array 20 is to be formed. Specifically, the recesses 22 are formed at the lattice points of a regular hexagonal lattice. The recesses 22 have a diameter of 70 μm, a depth of 120 μm, and an average pitch (the distance between lens centers) of 270 μm.

[0077] Figure 5 The conditions of steps S102 and S103 are as follows.

[0078] Light source: YAG laser,

[0079] Wavelength: 1030nm,

[0080] Pulse width: 5ps~10ps,

[0081] Pulse energy: 50 μJ,

[0082] Magnification of the condenser lens: 20 times.

[0083] The first modified layer 31 was formed so as to describe a circle with a diameter of 9 mm with respect to the first principal surface 11 and the second principal surface 12 of the glass substrate 10. The second modified layer 32 was formed so as to describe a circle with a diameter of 30 mm with respect to the first principal surface 11 and the second principal surface 12 of the glass substrate 10. The 9 mm diameter circle and the 30 mm diameter circle were arranged concentrically.

[0084] Figure 5 The conditions of step S104 are as follows.

[0085] Etching solution: a mixture of fluoric acid and hydrochloric acid,

[0086] Fluoric acid concentration: 2 mol / L,

[0087] Hydrochloric acid concentration: 4mol / L.

[0088] Step S104 is performed in sequence: bringing both the first main surface 11 and the second main surface 12 of the glass substrate 10 into contact with the etching liquid (S104a), sticking the adhesive tape to the second main surface 12 of the glass substrate 10 (S104b), and bringing only the first main surface 11 of the glass substrate 10 into contact with the etching liquid (S104c).

[0089] The time of S104a is set so that the glass substrate 10 is not completely broken at the positions where the first modified layer 31 and the second modified layer 32 are formed. In S104a, the etching amount of the first main surface 11 is 280 μm, and the etching amount of the second main surface 12 is 80 μm.

[0090] The time of S104c is set so that the glass substrate 10 is completely cut at the positions where the first modified layer 31 and the second modified layer 32 are formed. In S104c, the etching amount of the first main surface 11 is 20 μm.

[0091] In Example 1, 25 diffuser plates 2 were manufactured using the above-described manufacturing method. The glass substrate 10 constituting each diffuser plate 2 had an inner diameter D1 of 9 mm, an outer diameter D2 of 30 mm, a width W1 of 1.0 mm, a width W2 of 1.5 mm, and a thickness T of approximately 0.7 mm (1.1 mm - 280 μm - 80 μm - 20 μm).

[0092] [Example 2]

[0093] In Example 2, 25 diffuser plates 2 were manufactured under the same conditions as in Example 1, except that the inner diameter of the area intended to form the lens array 20 was changed from 11 mm to 14 mm in S101. The glass substrate 10 constituting each diffuser plate 2 had an inner diameter D1 of 9 mm, an outer diameter D2 of 30 mm, a width W1 of 2.5 mm, a width W2 of 1.5 mm, and a plate thickness T of approximately 0.7 mm.

[0094] [Example 3]

[0095] In Example 3, 20 diffuser plates 2 were manufactured under the same conditions as in Example 1, except that the inner diameter of the area intended to form the lens array 20 was changed from 11 mm to 18 mm in S101. The glass substrate 10 constituting each diffuser plate 2 had an inner diameter D1 of 9 mm, an outer diameter D2 of 30 mm, a width W1 of 4.5 mm, a width W2 of 1.5 mm, and a thickness T of approximately 0.7 mm.

[0096] [Example 4]

[0097] In Example 4, 19 diffuser plates 2 were manufactured under the same conditions as in Example 1, except that the recessed portion 22 was formed in a circular region (diameter: 32 mm) in S101, S104 was performed after S101 instead of S102 and S103, and the glass substrate 10 was cut into a circular shape by cutting after step S104. The glass substrate 10 constituting each diffuser plate 2 had an inner diameter D1 of 9 mm, an outer diameter D2 of 30 mm, a width W1 of 0.0 mm, a width W2 of 0.0 mm, and a plate thickness T of approximately 0.7 mm.

[0098] [evaluate]

[0099] The strength of the diffuser plate 2 is measured by the ball-on-ring method. Figure 10 As shown in FIG. 1 , in order to generate maximum tensile stress on the inner periphery of the first principal surface 11 of the glass substrate 10, the glass substrate 10 was placed on a ring 81 with the first principal surface 11 facing downward, and a ball 82 inserted from above into the through-hole 19 of the glass substrate 10 was pressed downward to measure the breaking load (N) of the glass substrate 10. The inner diameter of the ring 81 was 25 mm, and the diameter of the ball 82 was 10 mm.

[0100] exist Figure 11 The measurement results of the fracture strength of the diffuser plates 2 according to Examples 1 to 3 are shown in Table 1. The measurement results of the fracture strength of the diffuser plate 2 according to Example 4 are also shown in Table 1.

[0101] [Table 1]

[0102]

[0103] Depend on Figure 11 As can be seen from Table 1 (mainly Table 1), the strength of the diffuser plate 2 can be improved by providing the annular first flat surface 17 having a width of 1.0 mm or more along the inner periphery of the first main surface 11 .

[0104] The following supplementary notes are disclosed regarding the above-mentioned embodiments and the like.

[0105] [Supplementary Note 1] A diffuser plate, wherein:

[0106] The diffuser plate has:

[0107] a glass substrate having a first main surface and a second main surface facing opposite to the first main surface; and

[0108] A lens array is formed on the first main surface of the glass substrate.

[0109] When the first main surface of the glass substrate is observed from the front, the glass substrate and the lens array each have a ring shape, and the lens array includes a plurality of lenses.

[0110] The first main surface of the glass substrate has a first annular flat surface with a width of 1.0 mm or more between the inner periphery of the glass substrate and the inner periphery of the lens array, or has a second annular flat surface with a width of 1.0 mm or more between the outer periphery of the glass substrate and the outer periphery of the lens array.

[0111] [Supplementary Note 2] The diffuser plate according to Supplementary Note 1, wherein

[0112] The first main surface of the glass substrate has a first annular flat surface with a width of 2.5 mm or more between the inner periphery of the glass substrate and the inner periphery of the lens array, or has a second annular flat surface with a width of 2.5 mm or more between the outer periphery of the glass substrate and the outer periphery of the lens array.

[0113] [Supplementary Note 3] The diffuser plate according to Supplementary Note 1 or 2, wherein

[0114] The glass substrate has a thickness of 0.2 mm to 2.0 mm.

[0115] [Supplementary Note 4] The diffuser plate according to Supplementary Note 3, wherein

[0116] The glass substrate has a thickness of 0.5 mm to 1.0 mm.

[0117] [Supplementary Note 5] A method for manufacturing a diffuser plate, the method for manufacturing a diffuser plate according to any one of Supplementary Notes 1 to 4, comprising:

[0118] forming a concave portion by irradiating a first laser beam on the first main surface of the glass substrate at a predetermined position where each of the lenses is to be formed;

[0119] irradiating a predetermined position of the glass substrate where the inner periphery is to be formed with a second laser beam to form a first modified layer;

[0120] irradiating a predetermined position of the glass substrate where the outer periphery is to be formed with a third laser beam to form a second modified layer;

[0121] The glass substrate on which the recessed portion, the first modified layer, and the second modified layer are formed is wet-etched, thereby forming the lens array, the inner periphery of the glass substrate, and the outer periphery of the glass substrate at the same time.

[0122] [Supplementary Note 6] The method for manufacturing a diffuser plate according to Supplementary Note 5, wherein:

[0123] The wavelength of the first laser beam is 9.2 μm to 10.8 μm, the wavelength of the second laser beam is 1000 nm to 1100 nm, and the wavelength of the third laser beam is 1000 nm to 1100 nm.

[0124] [Supplementary Note 7] A projection device, wherein:

[0125] have:

[0126] The diffuser plate according to any one of Notes 1 to 4;

[0127] A rotation axis is embedded in the through hole in the center of the glass substrate;

[0128] a rotary motor to rotate the diffusion plate together with the rotation shaft; and

[0129] The light source irradiates the light to be diffused by the lens array toward the diffusion plate at a predetermined distance from the rotation center line of the rotation axis.

[0130] While the diffuser plate, diffuser plate, and method for manufacturing a projection device according to the present disclosure have been described above, the present disclosure is not limited to the aforementioned embodiments. Various changes, modifications, substitutions, additions, deletions, and combinations may be made within the scope of the claims. These also fall within the technical scope of the present disclosure.

[0131] This application claims priority based on Japanese Patent Application No. 2023-014159 filed with the Japan Patent Office on February 1, 2023, and the entire contents of Japanese Patent Application No. 2023-014159 are incorporated herein by reference.

[0132] Description of Reference Numerals

[0133] 2...diffuser plate; 10...glass substrate; 11...first main surface; 12...second main surface; 17...first flat surface; 18...second flat surface; 20...lens array; 21...lens.

Claims

1. A diffuser plate, wherein: The diffuser plate comprises: a glass substrate having a first main surface and a second main surface facing opposite to the first main surface; and a lens array formed on the first main surface of the glass substrate, When the first main surface of the glass substrate is viewed from the front, the glass substrate and the lens array each have a ring shape, and the lens array includes a plurality of lenses. The first main surface of the glass substrate has a first annular flat surface with a width of 1.0 mm or more between the inner periphery of the glass substrate and the inner periphery of the lens array, or has a second annular flat surface with a width of 1.0 mm or more between the outer periphery of the glass substrate and the outer periphery of the lens array.

2. The diffuser plate according to claim 1, wherein The first main surface of the glass substrate has a first annular flat surface with a width of 2.5 mm or more between the inner periphery of the glass substrate and the inner periphery of the lens array, or has a second annular flat surface with a width of 2.5 mm or more between the outer periphery of the glass substrate and the outer periphery of the lens array.

3. The diffuser plate according to claim 1 or 2, wherein: The glass substrate has a thickness of 0.2 mm to 2.0 mm.

4. The diffuser plate according to claim 3, wherein: The glass substrate has a thickness of 0.5 mm to 1.0 mm.

5. A method for manufacturing a diffuser plate, the method for manufacturing a diffuser plate according to claim 1 or 2, wherein: have: forming a concave portion by irradiating a first laser beam on the first main surface of the glass substrate at a predetermined position where each lens is to be formed; irradiating a predetermined position of the glass substrate where the inner periphery is to be formed with a second laser beam to form a first modified layer; irradiating a predetermined position of the glass substrate where the outer periphery is to be formed with a third laser beam to form a second modified layer; The lens array, the inner periphery of the glass substrate, and the outer periphery of the glass substrate are formed together by wet etching the glass substrate on which the recessed portion, the first modified layer, and the second modified layer are formed.

6. The method for manufacturing a diffuser plate according to claim 5, wherein: The wavelength of the first laser beam is 9.2 μm to 10.8 μm, the wavelength of the second laser beam is 1000 nm to 1100 nm, and the wavelength of the third laser beam is 1000 nm to 1100 nm.

7. A projection device, wherein: have: The diffuser plate according to claim 1 or 2; a rotation axis embedded in the through hole in the center of the glass substrate; a rotary motor to rotate the diffusion plate together with the rotation shaft; and The light source irradiates the diffuser plate with light to be diffused by the lens array at a predetermined distance from a rotation center line of the rotation axis.

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