CN113728254B

CN113728254B - Optical component

Info

Publication number: CN113728254B
Application number: CN202080029819.4A
Authority: CN
Inventors: 久保善则
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2019-04-25
Filing date: 2020-04-22
Publication date: 2023-08-22
Anticipated expiration: 2040-04-22
Also published as: CN113728254A; WO2020218350A1; JPWO2020218350A1; JP7238106B2

Abstract

The optical component according to the present disclosure includes a substrate including sapphire and having main surfaces facing each other, and a region colored with a doping material is present in at least a part of the main surfaces in a plan view.

Description

Optical component

Technical Field

The present invention relates to an optical member used in an optical device such as an image display device, and an image display device and a head-up display using the optical member.

Background

An image display device such as a projector device (PJ device) and a head-up display device (HUD device) is a device that irradiates image information displayed by an image forming section such as a liquid crystal panel onto a wall, a screen, a window, or the like using a light source and various optical elements, so that a user visually recognizes the image information. Such a device is provided with various optical components.

As one of the optical components, a color wheel is exemplified. The color wheel is an optical member used for displaying a color image. For example, patent document 1 describes a projector device including a color wheel. Conventionally, a coloring portion of a color wheel includes a phosphor or the like. In general, most of the light irradiated from the light source to the fluorescent material is converted into heat, which causes heat generation in the color wheel.

Prior art literature

Patent literature

Patent document 1: JP-A2011-186132

Disclosure of Invention

The optical component according to the present disclosure includes a substrate including sapphire and having main surfaces facing each other, and a region colored with a dopant material is present in at least a part of the main surfaces in a plan view.

An image display device according to the present disclosure includes: a light source, and the optical member positioned on the optical path of the light emitted from the light source. The head-up display according to the present disclosure includes: the image display device includes a display unit for displaying an image.

Drawings

Fig. 1 is an explanatory view showing a color wheel as an optical component according to an embodiment of the present disclosure, in which (a) is a plan view, and (B) is an explanatory view showing a cross section at the time of cutting by an X-X' line.

Fig. 2 is an explanatory diagram showing a crystal structure of sapphire.

Fig. 3 is a schematic view for explaining a step structure layer.

Detailed Description

A color wheel (optical member) used in an image display device such as a HUD device is required to improve light conversion efficiency (for example, conversion efficiency to RGB color light) with respect to light from a light source. In recent years, such demands have been further increased in image display devices in which the density and definition of the displayed image have been increased.

The optical component according to the present disclosure includes a substrate including sapphire and having main surfaces facing each other, and a region colored with a dopant material is present in at least a part of the main surfaces in a plan view. Therefore, the light conversion efficiency with respect to the light from the light source is improved, and the light conversion efficiency is also advantageous in terms of improvement of brightness and improvement of heat radiation property to the outside (reduction of heat generation).

An optical component according to an embodiment of the present disclosure will be described with reference to fig. 1. The optical member (color wheel) 1 shown in fig. 1 (a) has a substrate 2, and a colored region 3 is present when the main surface of the substrate 2 is viewed from above.

The substrate 2 has main surfaces facing each other, and the main surfaces have a circular shape in a plan view. The size of the substrate 2 is not particularly limited, and is appropriately set according to the size of the image display device or the like to be mounted. The substrate 2 may have a diameter of, for example, 10mm or more and 100mm or less, and may have a thickness of, for example, 0.1mm or more and 1mm or less.

The substrate 2 comprises sapphire. Sapphire is alumina (Al ₂ O ₃ ) Is a single crystal of (a). Sapphire has excellent heat resistance, heat conductivity and heat dissipation, and can suppress the temperature rise of the color wheel. Further, sapphire is excellent in mechanical strength, is hardly damaged even by a relatively strong centrifugal force, and is also excellent in light transmittance. Examples of such a substrate 2 include a sapphire substrate. In a substantially central portion of the main surface of the substrate 2, as shown in fig. 1 (B), a fixing hole 21 for fixing to the rotation holding portion is formed.

The transmittance of the substrate 2 is not limited. The substrate 2 containing sapphire has a relatively high transmittance, and for example, the transmittance at a wavelength of 400 to 800nm of the sapphire substrate 2 containing no doping material 4 for coloring is 82% or more. In the sapphire substrate 2 containing the doping material 4, a part of the light thereof is further absorbed, thereby forming colored light. The transmittance (i.e., conversion efficiency) of the colored light depends on the kind and concentration of the doping material 4, but is larger than the conversion efficiency (e.g., several%) of the phosphor. Therefore, heat generation due to coloring can be reduced. The light transmittance can be measured using, for example, an ultraviolet-visible near-infrared spectrophotometer.

Next, a crystal plane of sapphire will be described. Fig. 2 shows a crystal structure of sapphire. As shown in fig. 2 (a) to (D), sapphire has a hexagonal structure, and c-plane, m-plane, a-plane, and r-plane are typical crystal planes. The axes perpendicular to these planes are referred to as c-axis, m-axis, a-axis, and r-axis, respectively. In the color wheel 1, the substrate 2 may be processed to have an arbitrary crystal surface of sapphire as a main surface, and particularly, a substrate processed to have a c-surface of sapphire as a main surface is preferable because birefringence (anisotropy of refractive index) does not occur. The substrate processed to have the a-plane of sapphire as the main surface is excellent in mechanical strength.

The colored region 3 existing in the color wheel 1 includes a 1 st colored region 31, a 2 nd colored region 32, and a 3 rd colored region 33, and each colored region 3 is colored in a different color. The 1 st colored region 31, the 2 nd colored region 32, and the 3 rd colored region 33 are each formed in an annular fan shape having a center angle of approximately 120 ° in a plan view.

The colored region 3 is colored by adding the doping material 4 to the 1 st colored region 31, the 2 nd colored region 32, and the 3 rd colored region 33 as shown in fig. 1 (B), respectively. Hereinafter, the color wheel 1 will be described by taking an RGB color wheel as an example. The term "RGB" means three primary colors of red, green and blue.

The doping material 4 is not limited as long as it is a material for developing the 1 st colored region 31, the 2 nd colored region 32, and the 3 rd colored region 33 into different desired colors. As such a doping material 4, for example, a substance containing a metal element is cited. Specifically, compounds containing elements such as Cr (chromium), co (cobalt), fe (iron), ti (titanium), and Ni (nickel) are listed. For example, when each of the colored regions 3 is colored with a different doping material 4 in a different color, such a doping material 4 as follows is used.

When the 1 st colored region 31 is colored red, a compound containing Cr element such as chromium oxide is used as the doping material 4. When the 2 nd colored region 32 is colored green, a compound containing Co element such as cobalt oxide is used as the doping material 4. When the 2 nd colored region 33 is colored blue, a compound containing an Fe element such as iron oxide (and titanium oxide) is used as the doping material 4. When the 2 nd colored region 33 is colored yellow, a compound containing Ni element such as nickel oxide is used as the doping material 4. Such a compound (doping material 4) may be used alone in each colored region 3, and two or more kinds may be used in combination as long as color development is not inhibited. The amount of the dopant 4 to be added is also appropriately set in consideration of the color development shade, the size and thickness of the substrate 2, and the like. The doping material 4 is added, for example, at a concentration of about 100 to 50000ppm relative to the mass of the sapphire in the colored region 3.

Alternatively, two or more different doping materials 4 may be used in combination, and the mixture ratio of the regulators may be used to develop a desired color. In this case, the types of the plurality of dopant materials contained in each of the 1 st colored region 31, the 2 nd colored region 32, and the 3 rd colored region 33 may be the same in each region. For example, iron oxide, titanium oxide, and nickel oxide may be added to sapphire, and the addition amounts thereof may be adjusted to color the sapphire yellow to yellow green to blue.

The outer peripheral surface of the color wheel 1, that is, the substrate side surface 22 shown in fig. 1 (B), may be smooth, or the step structure layer 5 may be formed at least in part. The step structure layer 5 is described based on fig. 3.

The step structure layer 5 includes: a step surface 6 and a side surface 8 abutting against an edge line 7 of the step surface 6. The step surface 6 is a surface that expands to be planar. The side surface 8 is a surface extending substantially perpendicularly from the edge line 7 of one step surface 6 to the other step surface 6. As shown in fig. 3, the step structure layer 5 has a concave-convex shape. Therefore, when such a step structure layer 5 is formed on the substrate side surface 22, the surface area of the substrate side surface 22 can be increased as compared with the case of smoothing. By increasing the surface area of the substrate side surface 22, the heat dissipation from the substrate side surface 22 can be improved. The irregularities of the step structure layer 5 are different from extremely sharp concave or convex portions that easily become starting points of cracks and breaks.

The step surface 6 on which the step structure layer 5 is formed has, for example, 1 μm ² Above and 100 μm ² The following areas. The side surface 8 has a height at which at least an edge existing at the boundary between the step surface 6 and the side surface 8 can be recognized when observed by an electron microscope at about 3000 times. Specifically, the side surface 8 has a height of several atomic layers or more and 0.1 μm or less.

The method of manufacturing the color wheel 1 according to the embodiment is not limited, and is obtained by the following method, for example. The substrate 2 is prepared. When a sapphire substrate is used as the substrate 2, for example, a sapphire ingot is cut and processed to have a desired size, for example, a diameter of 10mm or more and 100mm or less and a thickness of 0.1mm or more and 1mm or less, thereby obtaining the substrate 2.

Next, a fixing hole 21 for fixing the obtained color wheel 1 to the rotation holding portion is formed in the substantially central portion of the substrate 2. Then, the substrate 2 was processed by a polishing apparatus so that the arithmetic average roughness Ra of both main surfaces was 1 μm or less. The polishing may be performed using, for example, a flat plate made of cast iron and diamond abrasive grains.

The arithmetic average roughness Ra is a value according to JIS B0601 (2013). The arithmetic average roughness Ra can be measured using, for example, a laser microscope device VK-9510 (manufactured by KEYENCE CORPORATION). For example, the measurement conditions may be such that the measurement mode is color super-depth, the measurement magnification is 1000 times, the measurement pitch is 0.02 μm, the cut-off filter λs is 2.5 μm, the cut-off filter λc is 0.08mm, and the measurement length is 100 to 500 μm.

After the polishing step, CMP (Chemical Mechanical Polishing) polishing using colloidal silica may be performed. The mirror polishing is performed so that the arithmetic average roughness Ra of both principal surfaces of the substrate 2 is, for example, 0.2 μm or less, whereby the substrate 2 having a smooth principal surface can be obtained. The mirror polishing process may be performed so that the arithmetic average roughness Ra of both main surfaces of the substrate 2 is 30nm or less. By performing CMP polishing, the number of processing damage layers on both main surfaces of the substrate 2 can be reduced, and the light transmittance can be further improved.

The step structure layer 7 may be formed on the substrate side surface 22 as needed. Specifically, the step structure layer 7 may be formed between the polishing step and the CMP polishing step. The step structure layer 7 is formed by performing heat treatment on the substrate side surface 22. Specifically, the substrate 2 is treated at a temperature of about 1800 ℃ to 2000 ℃ for 5 hours to more than 6 hours, and cooled to room temperature, thereby forming the step structure layer 7.

The heat treatment may be performed in an inert gas atmosphere such as argon or in vacuum. By performing the heat treatment in this way, the atoms and crystal defects are rearranged on the surface and inside of the substrate 2, and microcracks, crystal defects, or internal stress formed on the surface and inside during the processing step can be reduced. By the heat treatment, the step structure layer 7 is formed not only on the substrate side surface 22 but also on both main surfaces of the substrate. However, the step structure layer 7 formed on both main surfaces of the substrate is polished and removed by the subsequent CMP polishing step. As a result, the step structure layer 7 remains only on the substrate side surface 22.

Next, the substrate 2 is divided into a 1 st colored region 31, a 2 nd colored region 32, and a 3 rd colored region 33. The color wheel 1 is obtained by adding the desired doping material to the respective colored regions 3. As described above, the color wheel 1 according to the embodiment is manufactured without combining substrates that have been colored in advance in various colors, and can be manufactured by dividing one substrate 2 into a plurality of colored regions 3 and developing the same into different colors. The doping material 4 can be added by a method based on addition of an ion beam or the like, thermal diffusion after application in a paste form, or the like. The addition of the doping material 4 may be performed before the CMP polishing process.

The color wheel 1 according to the embodiment is provided so as to be positioned on the optical path of light emitted from the light source, and other members (for example, various lenses, a holding portion for holding and rotating the color wheel 1, a micromirror, and the like) are provided as necessary, thereby obtaining an image display device. Examples of the light source include white light (mercury lamp, etc.), ultraviolet light, LED, and laser.

When the light from the light source has a broad wavelength spectrum such as white light, the light is absorbed in a part of the wavelength region of the coloring region 3, and the transmitted light is colored. Therefore, the color conversion efficiency is higher than that of a color wheel that uses wavelength conversion such as fluorescence. Further, since light of a short wavelength among the incident light is easily absorbed, there is a tendency that the wavelength of the outgoing light becomes longer than that of the incident light. Therefore, the arithmetic average roughness Ra of the exit face (back face) may be set smaller than the arithmetic average roughness Ra of the entrance face (surface). The light-emitting surface (back surface) may be a non-mirror surface (arithmetic average roughness Ra is greater than 0.2 μm) to emit diffused light. In this way, when the back surface is a non-mirror surface, a diffusion plate is not required, and the structure of the image display device can be simplified (space saving and low cost).

The color wheel 1 according to the embodiment improves heat radiation to the outside and can be used even under relatively high temperature conditions. Examples of the image display device used under such high temperature conditions include an image display device (e.g., HUD device) mounted on a moving object such as a vehicle, a railway, a ship, or an airplane, and an image display device used outdoors, e.g., a HUD device for use in a vehicle.

The image light obtained by the HUD device is projected on a display section (screen) located outside the HUD device. Examples of the display unit include glass and a screen. In the case where the HUD device is used as a HUD device for a vehicle, examples of the display unit include a windshield, a rear glass, and a window of an automobile.

The optical component of the present disclosure is not limited to the optical component (color wheel) 1 according to the above-described embodiment. The color wheel 1 according to one embodiment is divided into three coloring areas 3. However, the colored region is not limited if it is divided into two or more. Specifically, in a case where the main surface of the substrate is viewed in plan, the main surface may be divided into n (n is an integer of 2 or more) sectors (annular sectors in the case where the fixing hole is present) having substantially the same center angle.

All of the three coloring areas 3 of the color wheel 1 according to one embodiment are colored. However, not all areas that need to be divided are colored. For example, the region divided into n regions as described above may be colored at least n-1. The uncolored region is used in the original color without changing the color of the light used as the light source.

The optical component of the present disclosure can be used as a color wheel, as well as other components such as a color filter. For example, in the color wheel 1 according to one embodiment, the main surface of the substrate 2 has a circular shape in a plan view. However, the main surface of the substrate may have a polygonal shape such as a triangular shape, a quadrangular shape, a pentagonal shape, or a hexagonal shape. In the case of such a polygonal shape, the optical member of the present disclosure is used as a color filter or the like, for example.

The optical member 1 of the present disclosure can also be used as a color filter used in combination with a light receiving device or a display device. For example, each colored region (31, 32, …) is formed by using a photolithography technique, whereby a high-resolution multicolor filter used in combination with a CCD (solid-state imaging device), a liquid crystal, or the like is obtained. In contrast to the conventional multicolor filters, which have boundary regions between colored regions that cannot be used as filters, the color filter of the present invention can produce a high-resolution color filter without such boundary regions.

Symbol description

1. Optical component (color wheel)

2. Substrate board

21. Fixing hole

22. Side of substrate

3. Colored regions

31. 1 st colored region

32. 2 nd colored region

33. 3 rd colored region

4. Doping material

5. Step structure layer

6. Step surface

7. Edge line

8. A side surface.

Claims

1. An optical member is provided with:

a substrate including sapphire and having main surfaces facing each other, one of the main surfaces being a light incident surface and the other being a light emitting surface,

in a planar main surface, at least a part of the main surface has a region colored with a doping material, and the arithmetic average roughness Ra of the emission surface is greater than 0.2 μm.

2. The optical component of claim 1, wherein,

the region colored by the doping material includes a plurality of regions colored in different colors.

3. The optical component of claim 1, wherein,

the region colored by the doping material has a plurality of regions colored by different doping materials to different colors.

4. The optical component of claim 1, wherein,

the region colored by the doping material has a plurality of regions containing the same plurality of doping materials and colored in different colors by adjustment of the mixing ratio of the respective doping materials.

5. The optical component according to any one of claims 1 to 4, wherein,

the doping material is a substance containing a metal element.

6. The optical component according to any one of claims 1 to 4, wherein,

the main surface has a circular shape in plan view.

7. The optical component of claim 6, wherein,

when the main surface is viewed from above, the main surface is divided into n fan-shaped regions having substantially the same center angle, and at least n-1 of the fan-shaped regions are colored in different colors by different doping materials, wherein n is an integer of 2 or more.

8. The optical component of claim 7, wherein,

the optical component is a color wheel.

9. The optical component according to any one of claims 1 to 4, wherein,

the main surface has a polygonal shape in a plan view.

10. The optical component of claim 9, wherein,

the optical component is a color filter.

11. An image display device is provided with: a light source, and the optical component of any one of claims 1 to 10 located on the optical path of light emitted from the light source.

12. A head-up display is provided with: the image display device according to claim 11, and a display unit for displaying an image.