阅读说明：本技术 光学部件 (Optical component ) 是由 久保善则 于 2020-04-22 设计创作，主要内容包括：本公开所涉及的光学部件具备包含蓝宝石并具有相互对置的主面的基板,在俯视主面的情况下,在至少一部分存在通过掺杂材料而被着色的区域。(The optical component according to the present disclosure includes a substrate including sapphire and having main surfaces facing each other, and a region colored by a dopant material is present in at least a part of the main surfaces in a plan view.)

1. An optical component is provided with:

a substrate including sapphire and having main surfaces opposed to each other,

in a plan view of the main surface, a region colored by the dopant material is present in at least a part thereof.

2. The optical component of claim 1,

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

3. The optical component of claim 1,

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

4. The optical component of claim 1,

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 member according to any one of claims 1 to 4,

the doping material is a substance containing a metal element.

6. The optical member according to any one of claims 1 to 5,

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

7. The optical component of claim 6,

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

8. The optical component according to claim 6 or 7,

the optical component is a color wheel.

9. The optical member according to any one of claims 1 to 5,

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

10. The optical component of claim 9,

the optical component is a color filter.

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

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

Technical Field

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

Background

Image display devices such as projector devices (PJ devices) and head-up display devices (HUD devices) are devices that use a light source and various optical elements to irradiate a wall, a screen, a window, and the like with image information displayed by an image forming unit such as a liquid crystal panel, so that a user visually recognizes the image information. Such a device includes various optical components.

As one of the optical components, a color wheel is cited. 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 and the like. In general, most of the light irradiated from the light source to the phosphor is converted into heat, which causes heat generation of the color wheel.

Prior art documents

Patent document

Patent document 1: JP 2011-186132 publication

Disclosure of Invention

An 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 described above positioned on the optical path of the light emitted from the light source. Furthermore, a 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 member according to an embodiment of the present disclosure, where (a) is a plan view, and (B) is an explanatory view showing a cross section when cutting along X-X' line.

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

Fig. 3 is a schematic diagram for explaining a step configuration layer.

Detailed Description

Color wheels (optical components) used in image display devices such as HUD devices are required to improve light conversion efficiency (for example, conversion efficiency into RGB color light) with respect to light from a light source. In recent years, such a demand has been further increased in image display devices in which the density and the definition of images to be displayed 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 efficiency of light conversion with respect to light from the light source is improved, and the improvement of luminance and the improvement of heat dissipation to the outside (reduction of heat generation) are also advantageous.

An optical component according to an embodiment of the present disclosure will be described with reference to fig. 1. An optical component (color wheel) 1 shown in fig. 1 (a) includes a substrate 2, and a colored region 3 in a plan view of a main surface of the substrate 2.

The substrate 2 has principal surfaces opposed to each other, and the principal 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 thereon. 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. The sapphire is aluminum oxide (Al)₂O₃) The single crystal of (1). Sapphire has excellent heat resistance, thermal conductivity and heat dissipation, and can restrain the temperature rise of the color wheel. Further, sapphire is excellent in mechanical strength, is hardly broken even by a relatively strong centrifugal force, and is also excellent in light transmittance. Examples of such a substrate 2 include a sapphire substrate. As shown in fig. 1 (B), a fixing hole 21 for fixing to the rotation holding portion is formed in a substantially central portion of the main surface of the substrate 2.

The transmittance of the substrate 2 is not limited. The sapphire substrate 2 has a relatively high transmittance, and the sapphire substrate 2, for example, which does not contain the coloring dopant 4, has a transmittance of 82% or more at a wavelength of 400 to 800 nm. In the sapphire substrate 2 containing the doping material 4, a part of the light is further absorbed, and colored light is formed. 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 explained. Fig. 2 shows a crystal structure of sapphire. As shown in fig. 2 (a) to (D), sapphire has a hexagonal structure, and typical crystal planes include a c-plane, an m-plane, an a-plane, and an r-plane. The axes perpendicular to these planes are referred to as the c-axis, the m-axis, the a-axis, and the r-axis, respectively. In the color wheel 1, the substrate 2 may be processed so that any crystal plane of sapphire becomes a main surface, and particularly, a substrate processed so that a c-plane of sapphire becomes a main surface is preferable because birefringence (anisotropy of refractive index) does not occur. Further, a substrate processed so that the a-plane of sapphire becomes a main surface is excellent in mechanical strength.

The coloring region 3 existing in the color wheel 1 includes a 1 st coloring region 31, a 2 nd coloring region 32, and a 3 rd coloring region 33, and the coloring regions 3 are colored in different colors. 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 sector shape having a central angle of substantially 120 ° in a plan view.

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

The dopant material 4 is not limited if it is a material that causes the 1 st colored region 31, the 2 nd colored region 32, and the 3 rd colored region 33 to respectively develop different desired colors. Examples of such a dopant 4 include a substance containing a metal element. Specifically, compounds containing elements such as Cr (chromium), Co (cobalt), Fe (iron), Ti (titanium), and Ni (nickel) are exemplified. For example, in the case where the respective colored regions 3 are colored in different colors with different dopant materials 4, the dopant materials 4 as follows are used.

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

Alternatively, two or more different kinds of the doping materials 4 may be used in combination and developed into a desired color by adjusting the mixing ratio. In this case, the kinds of the plurality of doping materials included in each of the 1 st, 2 nd, and 3 rd colored regions 31, 32, and 33 may be the same for each region. For example, iron oxide, titanium oxide, and nickel oxide can be added to sapphire, and the amounts of these added can be adjusted so that the sapphire develops yellow to yellow-green to blue colors.

The outer peripheral surface of the color wheel 1, i.e., 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 explained 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 expanded into a planar shape. 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 concavo-convex shape. Therefore, if the stepped structure layer 5 is formed on the substrate side surface 22, the surface area of the substrate side surface 22 can be increased compared to the case where it is smooth. 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 recesses or projections which are likely to become starting points of cracks or fractures.

The step surface 6 on which the step structure layer 5 is formed has a thickness of, for example, 1 μm²Above and 100 μm²The following area. The side surface 8 has a height at least as high as an edge existing at the boundary between the step surface 6 and the side surface 8 when observed with an electron microscope at a magnification of 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. A 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 a substantially central portion of the substrate 2. Then, the substrate 2 is processed by a polishing apparatus so that the arithmetic average roughness Ra of both main surfaces is 1 μm or less. The polishing may be performed using a flat plate made of cast iron and diamond abrasive grains, for example.

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

After the polishing step, cmp (chemical Mechanical polishing) polishing using colloidal silica may also be performed. The substrate 2 having smooth main surfaces can be obtained by performing mirror polishing so that the arithmetic average roughness Ra of both main surfaces of the substrate 2 is, for example, 0.2 μm or less. Mirror polishing 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 processing damage layers on both main surfaces of the substrate 2 can be reduced, and the light transmittance can be further improved.

If necessary, the step structure layer 7 may be formed on the substrate side surface 22. 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 processed at a temperature of about 1800 ℃ to 2000 ℃ for 5 hours or more and more than 6 hours or more 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 a vacuum. By performing the heat treatment in this manner, the rearrangement of the atoms and the crystal defects is performed on the surface and inside of the substrate 2, and the microcracks, the crystal defects, or the internal stress formed on the surface and inside in 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 layers 7 formed on both main surfaces of the substrate are 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 the 1 st colored region 31, the 2 nd colored region 32, and the 3 rd colored region 33. By adding the desired doping material to the respective colored areas 3, a color wheel 1 is obtained. As described above, the color wheel 1 according to the embodiment can be manufactured without combining substrates colored in various colors in advance, and one substrate 2 can be divided into a plurality of colored regions 3 and can be colored in different colors. The doping material 4 can be added by a method such as addition by ion beam or thermal diffusion after being applied in a paste form. The addition of the doping material 4 may be performed before the CMP polishing process.

The color wheel 1 according to one embodiment is provided so as to be positioned on the optical path of light emitted from a light source, and other components (for example, various lenses, a holding unit 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 (such as a mercury lamp), ultraviolet light, an LED, and a laser.

When light from the light source has a wide wavelength spectrum such as white light, the light is absorbed in a part of the wavelength region of the colored region 3, and the transmitted light is colored. Therefore, the color conversion efficiency becomes higher than that of a color wheel using wavelength conversion of fluorescence or the like. Further, since light having a short wavelength among incident light is easily absorbed, the wavelength of emitted light tends to be longer than that of the incident light. Therefore, the arithmetic average roughness Ra of the exit surface (back surface) can be set smaller than the arithmetic average roughness Ra of the entrance surface (front surface). The light-emitting surface (back surface) may be a non-specular surface (arithmetic mean roughness Ra is greater than 0.2 μm) to emit diffused light. In this way, when the rear surface is made non-mirror, the diffuser plate is not required, and the configuration of the image display device can be simplified (space saving and low cost).

The color wheel 1 according to an embodiment has improved heat dissipation 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 mobile body such as a vehicle, a railway, a ship, or an airplane, an image display device used outdoors, and an in-vehicle HUD device.

The image light obtained by the HUD device is projected on a display portion (screen) located outside the HUD device. Examples of the display unit include glass and a screen. When the HUD device is used as an in-vehicle HUD device, examples of the display unit include a windshield, a rear glass, and a window of an automobile.

The optical member of the present disclosure is not limited to the optical member (color wheel) 1 according to the above-described embodiment. The color wheel 1 according to an embodiment is divided into three colored regions 3. However, the colored region is not limited if it is divided into two or more. Specifically, when 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) fan-shaped regions (annular fan-shaped regions when the fixing holes are present) having substantially the same central angle.

In the color wheel 1 according to an embodiment, all of the three colored regions 3 are colored. However, it is not necessary that all the divided regions be colored. For example, the region divided into n regions and colored at least n-1 regions may be used as described above. The uncolored region is used as 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, and can also be used as another component such as a color filter. For example, in the color wheel 1 according to an 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 rectangular shape, a pentagonal shape, or a hexagonal shape. In such a case of having a polygonal shape, the optical member of the present disclosure is used as, for example, a color filter or the like.

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, by forming each colored region (31, 32, …) by using a photolithography technique, a high-resolution multicolor color filter used in combination with a CCD (solid-state imaging device), a liquid crystal, or the like is obtained. While the conventional multicolor color filter has boundary regions which cannot be used as filters between the respective colored regions, the color filter of the present invention can produce a high-resolution color filter without such boundary regions.

Description of the symbols

1 optical component (color wheel)

2 base plate

21 hole for fixing

22 side of the substrate

3 colored region

31 st colored region

32 nd 2 nd colored region

33 No. 3 colored region

4 doping material

5 step structural layer

6 step surface

7 edge line

8 sides.