Patent Application
20240385433
The invention relates to a light source unit and an image display device.
PCT Publication No. 2016/208195 discusses technology in which light emitted from a display device configured to display an image is sequentially reflected by multiple mirrors, and the light reflected by the final mirror is further reflected toward a user by a reflecting member such as a windshield or the like, so that the user views a virtual image corresponding to the image displayed by the display device.
An embodiment of the invention is directed to provide a light source unit and an image display device that are small and can display a high-quality image.
A light source unit according to an embodiment of the invention includes a display device configured to display an image, and an imaging optical system including an input element and an output element; light emitted from the display device is incident on the input element; light traveling via the input element is incident on the output element; and light emitted from the output element forms a first image corresponding to the image. The imaging optical system is substantially telecentric at the first image side. The light emitted from the display device has a substantially Lambertian light distribution.
An image display device according to an embodiment of the invention includes the light source unit, and a reflection unit that is separated from the light source unit and reflects light emitted from the imaging optical system. The first image is formed between the light source unit and the reflection unit.
According to an embodiment of the invention, a light source unit and an image display device that are small and can display a high-quality image can be provided.
Embodiments will now be described with reference to the drawings. The drawings are schematic or conceptual, and the relationships between the thickness and width of portions, the proportions of sizes among portions, etc., are not necessarily the same as the actual values. Also, the dimensions and proportions may be illustrated differently among drawings, even when the same portion is illustrated. Furthermore, in the specification and the drawings, components similar to those described in regard to an antecedent drawing are marked with the same reference numerals, and a detailed description is omitted as appropriate.
First, a first embodiment will be described.
Generally speaking, as shown in
For example, the image display device 10 is mounted in a vehicle 13 of an automobile or the like and is applied to a HUD (Head Up Display). Specifically, the greater part of the light reflected by the reflection unit 12 is reflected by a surface of a front windshield 13a of the vehicle 13 facing a user 14 inside the vehicle, i.e., the inner surface of the front windshield 13a, and enters an eyebox 14a of the user 14 that is a driver of the vehicle 13, etc. In other words, the inner surface of the front windshield 13a of the vehicle 13 functions as a reflecting surface. However, instead of the front windshield, the reflecting surface may be a surface of a combiner facing the user. As a result, the user 14 can view a second image IM2 corresponding to the image displayed by the display device 110. The second image IM2 is a virtual image that is larger than the first image IM1. In the specification, “eyebox” means the area of space in front of the eyes of the user where the virtual image is visible. In the drawings, similarly to the first image IM1, the position at which the second image IM2 is formed is shown by circular marks for easier understanding of the description. Similarly to the first image IM1, although the emission positions on the display device 110 and the arrival positions at the second image IM2 of the chief rays L are shown by marks of different shapes, the second image IM2 and the image displayed on the display device 110 have substantially similar shapes.
Components of the image display device 10 will now be elaborated. For easier understanding of the following description, the arrangements and configurations of the components are described using an XYZ orthogonal coordinate system. Hereinbelow, the direction in which an X-axis extends is called an “X-direction,” the direction in which a Y-axis extends is called a “Y-direction,” and the direction in which a Z-axis extends is called a “Z-direction.” According to the embodiment, an example is described in which the longitudinal direction of the vehicle 13 is along the “X-direction,” the lateral direction of the vehicle 13 is along the “Y-direction,” and the vertical direction of the vehicle 13 is along the “Z-direction.” In other words, in the following example, the XY-plane is the horizontal plane of the vehicle 13.
Also, hereinbelow, the X-direction in the direction of the arrow is called the “+X direction,” and the opposite direction also is called the “−X direction”. Also, the Y-direction in the direction of the arrow is called the “+Y direction,” and the opposite direction also is called the “−Y direction”. Also, the Z-direction in the direction of the arrow is called the “+Z direction,” and the opposite direction also is called the “−Z direction”. Also, a member A and a member B being arranged in this order in the +X direction is referred to as “the member B being positioned at the +X side of the member A” or “the member A being positioned at the −X side of the member B.” This is similar for the +Y direction and the +Z direction as well.
For example, the display device 110 of the light source unit 11 includes multiple pixels 110p, and is an LED display in which LED (Light Emitting Diode) elements 112 are located in the pixels 110p. For example, the display device 110 is electrically connected to a controller (not illustrated) mounted in the vehicle 13, and displays an image corresponding to the state of the vehicle 13.
As shown in
For example, the substrate 111 has a flat plate shape. The substrate 111 can include, for example, glass or a resin such as polyimide, etc. As shown in
As shown in
The semiconductor stacked body 112a includes a p-type semiconductor layer 112p1, an active layer 112p2 located on the p-type semiconductor layer 112p1, and an n-type semiconductor layer 112p3 located on the active layer 112p2. The semiconductor stacked body 112a includes, for example, a gallium nitride compound semiconductor of InXAlYGa1-X-YN (0≤X, 0≤Y, and X+Y<1). According to the embodiment, the light that is emitted by the LED element 112 is visible light.
The anode electrode 112b is electrically connected to the p-type semiconductor layer 112p1. Also, the anode electrode 112b is electrically connected to a wiring part 118a of the individual circuit 118 described below. The cathode electrode 112c is electrically connected to the n-type semiconductor layer 112p3. Also, the cathode electrode 112c is electrically connected to another wiring part 118a of the individual circuit 118 described below. The electrodes 112b and 112c can include, for example, a metal material.
According to the embodiment, multiple recesses 112t are provided in a light-emitting surface 112s of each LED element 112. In the specification, “the light-emitting surface of the LED element” means the surface of the LED element that mainly emits the light that is incident on the imaging optical system 120. According to the embodiment, the surface of the n-type semiconductor layer 112p3 that is positioned at the side opposite to the surface facing the active layer 112p2 corresponds to the light-emitting surface 112s. Examples of methods for providing the multiple recesses 112t in the surface of the n-type semiconductor layer 112p3 positioned at the side opposite to the surface facing the active layer 112p2 include, for example, a method in which multiple protrusions are formed in the upper surface of a growth substrate, and then the n-type semiconductor layer 112p3, the active layer 112p2, and the p-type semiconductor layer 112p1 are grown in this order on the growth substrate, and the n-type semiconductor layer 112p3 and the growth substrate are detached by LLO (Laser Lift Off) or the like, a method of performing surface roughening of the surface of the n-type semiconductor layer 112p3 to form the multiple recesses 112t after detaching the growth substrate, etc. Methods of surface roughening include anisotropic etching, etc.
Hereinbelow, the optical axis of the light emitted from each pixel 110p is called simply an “optical axis C.” As shown in
Thus, by providing the multiple recesses 112t in the light- emitting surface 112s of each LED element 112, the light that is emitted from each LED element 112, i.e., the light that is emitted from each pixel 110p, has a substantially Lambertian light distribution as shown by the broken line in
However, the configuration of each LED element is not limited to that described above. For example, multiple protrusions instead of multiple recesses may be provided in the light-emitting surface of each LED element, or both multiple recesses and multiple protrusions may be provided. Also, when the growth substrate is light-transmissive, the growth substrate may not be detached from the semiconductor stacked body, and multiple recesses and/or multiple protrusions may be provided in the surface of the growth substrate corresponding to the light-emitting surface. In such configurations as well, the light that is emitted from each LED element has a substantially Lambertian light distribution. Also, in each LED element, an n-type semiconductor layer may be provided to face the substrate, an active layer and a p-type semiconductor layer may be stacked in this order on the n-type semiconductor layer, and the surface of the p-type semiconductor layer at the side opposite to the surface facing the active layer may be used as the light-emitting surface of the LED element. Also, as described in other embodiments described below, it is sufficient for the light finally emitted from each pixel to have a substantially Lambertian light distribution, and the light that is emitted from each LED element may not have a substantially Lambertian light distribution.
For example, the scanning circuit 113, the scanning lines 114, the lighting control lines 115, the driver circuit 116, the signal lines 117, and the individual circuits 118 are formed by a low-temperature polysilicon (LTPS: Low Temperature Polycrystalline Silicon) process on the substrate 111.
As shown in
The driver circuit 116 is located in the substrate 111 to be adjacent in the Y-direction to the multiple LED elements 112 arranged in the matrix configuration when viewed in plan. The driver circuit 116 is a circuit configured to control the output of each LED element 112 belonging to the row 112i to be driven. The multiple signal lines 117 extend in the Y-direction from the driver circuit 116. The multiple signal lines 117 are arranged in the X-direction. The driver circuit 116 may include an IC chip, and the IC chip may be mounted on the substrate 111.
According to the embodiment, one individual circuit 118 corresponds to one LED element 112. However, multiple LED elements may be located in one pixel; in such a case, one individual circuit may correspond to the multiple LED elements in the one pixel. As shown in
As shown in
The gate electrode of the first transistor T1 is electrically connected to the lighting control line 115. The drain electrode of the first transistor T1 is electrically connected to the drain electrode of the second transistor T2 via the wiring part 118c. The source electrode of the second transistor T2 is electrically connected to a power supply line 119b via the wiring part 118d. The power supply line 119b is connected to a power supply (not illustrated).
The gate electrode of the second transistor T2 is electrically connected to the drain electrode of the third transistor T3 via the wiring part 118e. The source electrode of the third transistor T3 is electrically connected to the signal line 117. The gate electrode of the third transistor T3 is electrically connected to the scanning line 114.
The wiring part 118e is electrically connected to one terminal of the capacitor Cm. The other terminal of the capacitor Cm is electrically connected to the power supply line 119b.
The scanning circuit 113 selects one row among the multiple rows 112i and transmits an on-signal to the scanning line 114 electrically connected to the row 112i. As a result, the third transistors T3 of the individual circuits 118 corresponding to the row 112i are in a state in which the third transistors T3 can be switched on. Also, the driver circuit 116 transmits, to the signal lines 117, drive signals corresponding to the setting outputs of the LED elements 112 belonging to the row 112i. The drive signal voltages are thereby stored in the capacitors Cm. Also, the drive signal voltages set the second transistors T2 of the individual circuits 118 corresponding to the row 112i to a state in which the second transistors T2 can be switched on.
Also, the scanning circuit 113 transmits, to the lighting control line 115 electrically connected to the row 112i, a control signal that sequentially switches the first transistors T1 of the row 112i on and off. When the first transistors T1 are in the on-state, the light emission luminances of the LED elements are controlled by currents corresponding to the drive signal voltages stored in the capacitors Cm flowing in the LED elements 112 belonging to the row 112i. Also, the light emission periods of the LED elements 112 are controlled for each row 112i by switching the first transistors T1 on and off.
The scanning circuit 113 sequentially switches, in the Y-direction, the scanning line 114 transmitting the on-signal and the lighting control line 115 transmitting the control signal. Accordingly, the row 112i that is driven is sequentially switched in the Y-direction.
The configuration of the drive circuit including the scanning circuit, the multiple scanning lines, the multiple lighting control lines, the driver circuit, the multiple signal lines, the multiple individual circuits, etc., is not limited to the configuration described above. For example, the individual circuit may include a second transistor, a third transistor, a capacitor, and wiring parts without including a first transistor, only multiple scanning lines may extend from the scanning circuit, and a lighting control line may not be included. Also, the scanning lines, the lighting control lines, the signal lines, the wiring parts of the individual circuits, etc., may not be on the surface of the substrate, and may be provided in the substrate. Also, the electrical elements such as the transistors, capacitors, and the like included in the drive circuit may be separately manufactured and then mounted on the substrate instead of being formed on the substrate. Also, instead of separately manufacturing the LED elements and then mounting to the substrate, the LED elements may be formed on the substrate by using a semiconductor material such as silicon (Si) or the like as the substrate. Also, the configuration of the display device may not be an LED display as long as the emitted light has a substantially Lambertian light distribution.
The imaging optical system 120 of the light source unit 11 is an optical system that includes all of the optical elements necessary for forming the first image IM1 at the prescribed position. The embodiment includes an input element 121 on which the light emitted from the display device 110 is incident, and an output element 123 on which the light traveling via the input element 121 is incident. The imaging optical system 120 further includes an intermediate element 122 located between the input element 121 and the output element 123. The imaging optical system may not include an intermediate element. As shown in
The imaging optical system 120 is substantially telecentric at the first image IM1 side. Here, “the imaging optical system 120 is substantially telecentric at the first image IM1 side” means that the multiple chief rays L that are emitted from mutually-different positions of the display device 110, travel via the imaging optical system 120, and reach the first image IM1 are substantially parallel to each other before and after the first image IM1 as shown in
When the imaging optical system 120 is substantially telecentric at the first image IM1 side, the multiple chief rays L cross each other before being incident on the input element 121. Hereinbelow, the point at which the multiple chief rays L cross each other is called a “focal point F”. Therefore, for example, whether or not the imaging optical system 120 is substantially telecentric at the first image IM1 side can be confirmed by utilizing the backward propagation of light by the following method. First, a light source that can emit parallel light such as a laser light source or the like is provided at the vicinity of the position at which the first image IM1 is formed. The light that is emitted from the light source is irradiated on the output element 123 of the imaging optical system 120. The light that is emitted from the light source and travels via the output element 123 is incident on the input element 121. Then, if the light that is emitted from the input element 121 condenses at a point, i.e., the focal point F, before reaching the display device 110, then the imaging optical system 120 can be determined to be substantially telecentric at the first image IM1 side.
Because the imaging optical system 120 is substantially telecentric at the first image IM1 side, the light emitted from each pixel 110p that is mainly incident on the imaging optical system 120 is the light that passes through the focal point F and the vicinity of the focal point F. Optical elements included in the imaging optical system 120 will now be described.
The input element 121 is positioned at the −Z side of the display device 110 and arranged to face the display device 110. The input element 121 is a mirror that includes a concave mirror surface 121a. The input element 121 reflects the light emitted from the display device 110.
The intermediate element 122 is positioned at the −X side of the display device 110 and the input element 121 and arranged to face the input element 121. The intermediate element 122 is a mirror that includes a concave mirror surface 122a. The intermediate element 122 further reflects the light reflected by the input element 121.
The input element 121 and the intermediate element 122 are included in a bending part 120a that bends the multiple chief rays L so that the multiple chief rays L emitted from mutually-different positions of the display device 110 are substantially parallel to each other. According to the embodiment, the mirror surfaces 121a and 122a are biconic surfaces. However, the mirror surfaces may be portions of spherical surfaces or may be freeform surfaces.
The output element 123 is positioned at the +X side of the display device 110 and the input element 121 and arranged to face the intermediate element 122. The output element 123 is a mirror that includes a flat mirror surface 123a. The output element 123 reflects the light traveling via the input element 121 and the intermediate element 122 toward the formation position of the first image IM1. Specifically, the multiple chief rays L that are substantially parallel due to the bending part 120a are incident on the output element 123. The mirror surface 123a is tilted in the +X direction toward the −Z direction with respect to the XY-plane, i.e., the horizontal plane of the vehicle 13. As a result, the light that is reflected by the intermediate element 122 is reflected by the output element 123 in a direction tilted in the +X direction toward the −Z direction with respect to the Z-direction. Thus, as shown in
According to the embodiment, the optical path between the input element 121 and the intermediate element 122 extends in a direction crossing the XY-plane. Also, the optical path between the intermediate element 122 and the output element 123 extends in a direction along the XY-plane. Because a portion of the optical path inside the imaging optical system 120 extends in a direction crossing the XY-plane, the light source unit 11 can be somewhat smaller in directions along the XY-plane. Also, because another portion of the optical path inside the imaging optical system 120 extends in a direction along the XY-plane, the light source unit 11 can be somewhat smaller in the Z-direction.
Also, the optical path between the display device 110 and the input element 121 crosses the optical path between the intermediate element 122 and the output element 123. Thus, by causing the optical paths to cross each other inside the light source unit 11, the light source unit 11 can be downsized.
However, the optical paths inside the light source unit are not limited to those described above. For example, all of the optical paths inside the imaging optical system may extend in directions along the XY-plane or may extend in directions crossing the XY-plane. Also, the optical paths inside the light source unit may not cross each other.
The input element 121, the intermediate element 122, and the output element 123 each may include a main member made of glass, a resin material, or the like and a reflective film such as a metal film, a dielectric multilayer film, or the like forming the mirror surfaces 121a, 122a, and 123a located at the surface of the main member. Also, the input element 121, the intermediate element 122, and the output element 123 each may be entirely formed of a metal material.
According to the embodiment as shown in
Although the imaging optical system 120 is described above, the configuration and position of the coupling optical system are not limited to those described above as long as the coupling optical system is substantially telecentric at the first image side. For example, the number of optical elements included in the direction modifying part may be two or more.
According to the embodiment, the reflection unit 12 includes a mirror 131 that includes a concave mirror surface 131a. According to the embodiment, the mirror surface 131a is a biconic surface. However, the mirror surface may be a portion of a spherical surface or may be a freeform surface. As shown in
The mirror 131 may include a main member made of glass, a resin material, or the like and a reflective film such as a metal film, a dielectric multilayer film, or the like forming the mirror surface 131a located at the surface of the main member. Also, the mirror 131 may be entirely formed of a metal material.
According to the embodiment, the reflection unit 12 is located at a dashboard part 13c of the vehicle 13. For example, the reflection unit 12 is located at the inner side of a wall 13s2 of the dashboard part 13c of the vehicle 13 exposed inside the vehicle. A through-hole 13h2 through which the light emitted from the output element 123 of the light source unit 11 can pass is provided in the wall 13s2. The light that is emitted from the output element 123 passes through the through-hole 13h1, forms the first image IM1, subsequently passes through the through-hole 13h2, and is irradiated on the reflection unit 12. However, the reflection unit may be mounted to the upper surface of the dashboard part. Also, the reflection unit may be located at the ceiling part, and the light source unit may be located at the dashboard part.
The X-direction in which the eyebox 14a and the inner surface of the front windshield 13a face each other is taken as a first direction, and the Z-direction orthogonal to the first direction is taken as a second direction. As shown in
Although the reflection unit 12 is described above, the configuration and position of the reflection unit are not limited to those described above. For example, the number of optical elements such as mirrors and the like included in the reflection unit may be two or more. It goes without saying that the reflection unit 12 must be arranged so that, for example, sunlight that is irradiated from outside the vehicle via the front windshield 13a is not reflected toward the eyebox 14a.
Effects of the embodiment will now be described.
In the light source unit 2011 according to the reference example, a display device 2110 is an LCD (Liquid Crystal Display) that includes multiple pixels 2110p. In
In the display device 2110 of the reference example as shown in
In such a display device 2110, the luminous intensity and/or chromaticity changes according to the viewing angle of the user, even when the light is emitted from the same position of the display device 2110. Accordingly, even when the luminance of the light emitted from all of the pixels is uniform, the luminance and/or chromaticity of the first image IM1 fluctuate if the imaging optical system 2120 receives the light emitted from the display device 2110 from directions other than the normal direction. In other words, the quality of the first image IM1 degrades. Accordingly, to prevent degradation of the quality of the first image IM1, it is necessary to receive the light emitted from each pixel 2110p of the display device 2110 from the normal direction. As a result, the imaging optical system 2120 is larger.
In contrast, in the light source unit 11 according to the embodiment, the imaging optical system 120 is substantially telecentric at the first image IM1 side, and the light emitted from the display device 110 has a substantially Lambertian light distribution. Therefore, the quality of the first image IM1 can be improved while downsizing the light source unit 11. Specifically, because the light emitted from the display device 110 has a substantially Lambertian light distribution, the dependence on the angle of the luminous intensity and/or chromaticity of the light emitted from the pixels 110p of the display device 110 is less than the dependence on the angle of the luminous intensity and/or chromaticity of the light emitted from the pixels 2110p of the display device 2110 according to the reference example. In particular, as an exact Lambertian light distribution is approached, that is, as the approximation formula of the light distribution pattern approaches cosn θ in which n is 1, the luminous intensity and/or chromaticity of the light emitted from each pixel 110p of the display device 110 is substantially uniform regardless of the angle. Therefore, as shown in
Also, the image display device 10 according to the embodiment includes the light source unit 11, and the reflection unit 12 that is separated from the light source unit 11 and reflects the light emitted from the imaging optical system 120. The first image IM1 is formed between the light source unit 11 and the reflection unit 12. In such a case, the light that is emitted from one point of the display device 110 is condensed at the formation position of the first image IM1 after traveling via the output element 123. On the other hand, when the first image IM1 is not formed between the light source unit 11 and the reflection unit 12, the light diameter of the light emitted from one point of the display device 110 gradually spreads from the input element 121 toward the reflection unit 12. Accordingly, in the output element 123 according to the embodiment, the range in which the light emitted from one point of the display device 110 is irradiated can be less than when the first image IM1 is not formed. Therefore, the output element 123 can be smaller.
Also, because the light source unit 11 according to the embodiment is small, the light source unit 11 can be easily arranged in the limited space inside the vehicle 13 when the light source unit 11 is mounted in the vehicle 13 and used as a head-up display.
Also, according to the embodiment, the imaging optical system 120 includes the bending part 120a and the direction modifying part 120b. Thus, the design of the imaging optical system 120 is easier because the part of the imaging optical system 120 having the function of making the chief rays L parallel to each other and the part of the imaging optical system 120 forming the first image IM1 at the desired position are separate.
Also, a portion of the optical path inside the imaging optical system 120 extends in a direction crossing the XY-plane orthogonal to the Z-direction. Therefore, the imaging optical system 120 can be somewhat smaller in directions along the XY-plane.
Also, another portion of the optical path inside the imaging optical system 120 extends in directions along the XY-plane orthogonal to the Z-direction. Therefore, the imaging optical system 120 can be somewhat smaller in the Z-direction.
Light source units according to examples and a reference example will now be described.
The image display devices according to the examples 1 to 12 and the reference example were set in simulation software to include a light source unit and a reflection unit, wherein the light source unit included multiple light-emitting areas arranged in a matrix configuration and an imaging optical system. The light-emitting areas correspond to the pixels 110p of the display device 110 according to the embodiment described above.
In
In the examples 2 to 12, the light that was emitted from each light-emitting area was set in the simulation software to have a light distribution pattern in which the luminous intensity in the direction of the angle θ with respect to the optical axis was represented by cosn θ times the luminous intensity at the optical axis. In the example 2, n=2, and n was set to increase by one in order from the example 2 to the example 12.
Also, by investigating the light distribution pattern in one plane of the light emitted from the pixels of an LCD, the light distribution pattern was found to be a light distribution pattern such as that illustrated by the fine broken line of
The imaging optical systems of the examples 1 to 12 and the reference example each were set to be telecentric at the first image side.
Then, the luminance distribution of the second image formed when the luminance was constant for all light-emitting areas was simulated for the examples 1 to 12 and the reference example. In this case, the second image was a rectangle having a long side of 111.2 mm and a short side of 27.8 mm. Also, in this case, the plane in which the second image was formed was divided into square areas having sides of 1 mm, and the luminance value of each area is simulated. Some of the results are shown in
Also, the uniformity of the luminance of the second image was evaluated for this case. Herein, “the uniformity of the luminance” is the value of the ratio of the minimum value to the maximum value of the luminance inside the second image expressed in percent. The results are shown in
As shown in
Accordingly, it was found that when the imaging optical system is configured to be substantially telecentric, it is favorable for the light emitted from the display device to have a substantially Lambertian light distribution to suppress the uneven luminance of the first and second images. Specifically, it was found that it is favorable for n of cosn θ which is the approximation formula of the light distribution pattern to be not more than 11, and more favorably 1. Although the uniformity of the luminance of the second image IM2 degrades as n deviates from 1 as described above, a prescribed luminance distribution can be pre-provided in the display luminance of the display device 110 to remedy such nonuniformity of the luminance. For example, when the luminance at the outer edge portion of the second image IM2 tends to be less than the luminance at the central portion due to the light emitted from the pixels 110p of the display device 110 traveling via the imaging optical system 120, the display device 110 may be controlled so that the outputs of the LED elements 112 of the pixels 110p at the outer edge vicinity of the display device 110 to be greater than the outputs of the LED elements 112 of the pixels 110p at the center.
A second embodiment will now be described.
The orientation of the display device 110 and the configuration of an imaging optical system 220 of the light source unit 21 according to the embodiment are different from those of the light source unit 11 according to the first embodiment.
As a general rule in the following description, only the differences with the first embodiment are described. Other than the items described below, the embodiment is similar to the first embodiment. This is similar for the other embodiments described below as well.
In the display device 110 according to the embodiment, the light-emitting surface 112s of the display device 110 is arranged to face the −X direction. However, the orientation of the display device is not limited to such an orientation.
The imaging optical system 220 includes an input element 221, an intermediate element 222, and an output element 223. The input element 221 and the intermediate element 222 are included in a bending part 220a, and the output element 223 is included in a direction modifying part 220b. A focal point F2 of the imaging optical system 220 is positioned between the display device 110 and the input element 221. In other words, the imaging optical system 220 is substantially telecentric at the first image IM1 side.
The input element 221 is a mirror that includes a concave mirror surface 221a. The input element 221 is located at the −X side of the display device 110 and faces the display device 110. The light that is emitted from the display device 110 is reflected by the input element 221. The intermediate element 222 is a mirror that includes a concave mirror surface 222a. The intermediate element 222 is located adjacent to the input element 221 in the Y-direction and faces the input element 221. The light that is reflected by the input element 221 is further reflected by the intermediate element 222. Multiple chief rays L2 that are emitted from mutually-different positions of the display device 110 and pass through the focal point F2 are bent to become substantially parallel to each other by being sequentially reflected by the input element 221 and the intermediate element 222.
The output element 223 is a mirror that includes a flat mirror surface 223a. The output element 223 is located at the +X side of the intermediate element 222 and faces the intermediate element 222. Similarly to the mirror surface 123a of the output element 123 according to the first embodiment, the mirror surface 223a is tilted in the +X direction toward the −Z direction with respect to the XY-plane. As a result, the output element 223 reflects the light reflected by the intermediate element 222 in a direction tilted with respect to the Z-direction to be in the +X direction toward the −Z direction.
The optical path between the input element 221 and the intermediate element 222 and the optical path between the intermediate element 222 and the output element 223 extend in directions along the XY-plane. As a result, the imaging optical system 220 can be smaller in the Z-direction.
A third embodiment will now be described.
The light source unit 31 according to the embodiment differs from the light source unit 21 according to the second embodiment in that a light-shielding member 340 is further included. In
The light-shielding member 340 is located between the display device 110 and the input element 221 of the imaging optical system 220. For example, the light-shielding member 340 has a flat plate shape substantially parallel to the ZY-plane. An aperture 341 that extends through the light-shielding member 340 in the X-direction is provided in the light-shielding member 340. The focal point F2 of the imaging optical system 220 is positioned inside the aperture 341. The light that is emitted from the display device 110 and passes through the focal point F2 and the vicinity of the focal point F2 passes through the aperture 341 of the light-shielding member 340 and is incident on the input element 221, and the greater part of the light other than the light passing through the aperture 341 is shielded by the light-shielding member 340.
As described above, the light source unit 31 according to the embodiment further includes the light-shielding member 340 that is located between the display device 110 and the imaging optical system 220, the aperture 341 that transmits a portion of the light from the display device 110 toward the imaging optical system 220 is provided in the light-shielding member 340, and the light-shielding member 340 shields another portion of the light from the display device 110 toward the imaging optical system 220. Therefore, the light that is emitted by the display device 110 and does not pass through the focal point F2, i.e., ineffective light, can be prevented from being incident on the imaging optical system 220. The occurrence of stray light can be suppressed thereby. Also, when light such as sunlight or the like from outside the light source unit 11 penetrates the light source unit 31, the light can be prevented from traveling toward the display device 110. An increase of the temperature of the display device 110 can be suppressed thereby. This is because problems such as deviation of the optical axis due to thermal expansion, etc., occur when the temperature of the display device 110 rises to become a prescribed value or more.
A fourth embodiment will now be described.
The orientation of the display device 110 and the configuration of an imaging optical system 420 of the light source unit 41 according to the embodiment are different from those of the light source unit 11 according to the first embodiment.
According to the embodiment, the display device 110 is arranged so that the light-emitting surface 112s of the display device 110 faces a direction between the +Z direction and the +Y direction. However, the orientation of the display device is not limited to such an orientation.
The imaging optical system 420 includes an input element 421, an intermediate element 422, and an output element 423. The input element 421 and the intermediate element 422 are included in a bending part 420a, and the output element 423 is included in a direction modifying part 420b. A focal point F4 of the imaging optical system 420 is positioned between the display device 110 and the input element 421. In other words, the imaging optical system 420 is substantially telecentric at the first image IM1 side.
The input element 421 is a mirror that includes a concave mirror surface 421a. The input element 421 is located at the +Y side and +Z side of the display device 110 and faces the display device 110. The light that is emitted from the display device 110 is reflected by the input element 421. The intermediate element 422 is a mirror that includes a concave mirror surface 422a. The intermediate element 422 is located at the −X side and −Y side of the input element 421 and faces the input element 421. The light that is reflected by the input element 421 is further reflected by the intermediate element 422. Multiple chief rays L4 that are emitted from mutually-different positions of the display device 110 and pass through the focal point F4 are bent by being sequentially reflected by the input element 421 and the intermediate element 422 to become substantially parallel to each other.
The configuration of the output element 423 is similar to the configuration of the output element 123 according to the first embodiment, and a description is therefore omitted.
The optical path between the input element 421 and the intermediate element 422 extends in a direction crossing the XY-plane which is the horizontal plane of the vehicle 13. Also, the optical path between the intermediate element 422 and the output element 423 extends in a direction along the XY-plane. As a result, the imaging optical system 420 can be smaller in directions along the Z-direction and the XY-plane.
A fifth embodiment will now be described.
The orientation of the display device 110 and the configuration of an imaging optical system 520 of the light source unit 51 according to the embodiment are different from those of the light source unit 11 according to the first embodiment.
According to the embodiment, the display device 110 is arranged so that the light-emitting surface 112s of the display device 110 faces the +X direction. However, the orientation of the display device is not limited to such an orientation.
The imaging optical system 520 includes an input element 521, an intermediate element 522, and an output element 523. The input element 521 and the intermediate element 522 are included in a bending part 520a, and the output element 523 is included in a direction modifying part 520b. A focal point F5 of the imaging optical system 520 is positioned between the display device 110 and the input element 521. In other words, the imaging optical system 520 is substantially telecentric at the first image IM1 side.
According to the embodiment, the input element 521 is a lens on which the light emitted from the display device 110 is incident. The input element 521 is located at the +X side of the display device 110 and faces the display device 110. According to the embodiment, the intermediate element 522 is a lens on which the light emitted from the input element 521 is incident. The intermediate element 522 is located at the +X side of the input element 521 and faces the display device 110. Multiple chief rays L5 are emitted from mutually-different positions of the display device 110, pass through the focal point F5, are bent by being refracted by the input element 521 and the intermediate element 522, and become substantially parallel to each other. Although an example is shown in
The configuration of the output element 523 is similar to the configuration of the output element 123 according to the first embodiment, and a description is therefore omitted.
The optical path between the input element 521 and the intermediate element 522 and the optical path between the intermediate element 522 and the output element 523 extend in a direction along the XY-plane. As a result, the imaging optical system 220 can be smaller in the Z-direction.
As described above, the optical elements such as the input element 521, the intermediate element 522, etc., included in the imaging optical system 520 may be lenses. By such a configuration as well, the light source unit 51 that is small and can display a high-quality image can be provided. Also, the number of lenses included in the imaging optical system may be one, three, or more.
A sixth embodiment will now be described.
The orientation of the display device 110 and the configuration of an imaging optical system 620 of the light source unit 61 according to the embodiment are different from those of the light source unit 11 according to the first embodiment.
According to the embodiment, the display device 110 is arranged to have an orientation such that the light-emitting surface 112s of the display device 110 faces a direction between the +X direction and the +Z direction. However, the orientation of the display device is not limited to such an orientation.
According to the embodiment, the imaging optical system 620 is made of one optical element 621. The optical element 621 is, for example, a mirror that includes a concave mirror surface 621a. The optical element 621 is located at the +Z side and +X side of the display device 110 and faces the display device 110. A focal point F6 of the optical element 621 is positioned between the display device 110 and the optical element 621. Multiple chief rays L6 that are emitted from mutually-different positions of the display device 110 and pass through the focal point F6 become substantially parallel to each other by being reflected by the optical element 621. Also, the travel directions of the multiple chief rays L6 are modified by being reflected by the optical element 621 so that the multiple chief rays L6 that are emitted from mutually-different positions of the display device 110 and pass through the focal point F6 travel toward the formation position of the first image IM1.
As described above, the imaging optical system 620 may be made from one optical element 621. By such a configuration as well, the light source unit 61 that is small and can display a high-quality image can be provided. According to the orientation and/or position of the display device, one optical element included in the imaging optical system may be a lens.
A seventh embodiment will now be described.
The display device 710 according to the embodiment differs from the display device 110 according to the first embodiment in that the surface of an n-type semiconductor layer 712p3 positioned at the side opposite to the surface facing the active layer 112p2 is substantially flat, and a protective layer 714, a wavelength conversion member 715, and a color filter 716 are further included.
The protective layer 714 covers multiple LED elements 712 arranged in a matrix configuration. The protective layer 714 can include, for example, a light-transmitting material such as a polymer material that includes a sulfur (S)-including substituent group or a phosphorus (P) atom-including group, a high refractive index nanocomposite material in which inorganic nanoparticles having a high refractive index are introduced to a polymer matrix of polyimide, etc.
The wavelength conversion member 715 is located on the protective layer 714. The wavelength conversion member 715 includes at least one type of wavelength conversion material such as a general fluorescer material, a perovskite fluorescer material, a quantum dot (Quantum Dot: QD), etc. The light that is emitted from each LED element 712 is incident on the wavelength conversion member 715. The wavelength conversion material that is included in the wavelength conversion member 715 emits light of a different light emission peak wavelength from the light emission peak wavelength of the LED element 712 by the light emitted from the LED element 712 being incident on the wavelength conversion material. The light that is emitted by the wavelength conversion member 715 has a substantially Lambertian light distribution.
The color filter 716 is located on the wavelength conversion member 715. The color filter 716 is configured to shield the greater part of the light emitted from the LED element 712. Accordingly, the light that is emitted mainly by the wavelength conversion member 715 is emitted from each pixel 110p. Therefore, as illustrated by the broken line in
According to the embodiment, the light emission peak wavelength of the LED element 712 may be in the ultraviolet region or may be in the visible light region. When blue light is to be emitted from at least one pixel 110p, for example, blue light may be emitted from the LED element 712 of such a pixel 110p, and the wavelength conversion member 715 and the color filter 716 may not be provided for this pixel 110p. In such a case, the light that is emitted from the pixel 110p may have a substantially Lambertian light distribution by providing a light-scattering member including light-scattering particles to cover the LED element 712.
An eighth embodiment will now be described.
The image display device 80 according to the embodiment differs from the image display device 10 according to the first embodiment in that the travel direction of the light reflected by the reflection unit 12 is modifiable according to the pupil position of the user 14.
The image display device 80 further includes a driver 86 configured to modify the orientation of the reflection unit 12, a camera 87 configured to image the eye of the user 14, and a controller 88 that estimates the pupil position of the user 14 and controls the driver 86 according to the image that is imaged by the camera 87.
The driver 86 includes a first motor 86a and a second motor 86b configured to modify the orientation of the mirror 131 of the reflection unit 12, and a circuit 86c that drives the first motor 86a and the second motor 86b. For example, the first motor 86a is configured to rotate the mirror 131 around a rotation axis D1 extending in the Y-direction. For example, the second motor 86b is configured to rotate the mirror 131 around a rotation axis D2 extending in the X-direction. The circuit 86c is electrically connected to the first motor 86a, the second motor 86b, and the controller 88. Gears may be provided between the motors and the mirror. Also, the number of motors included in the driver may be one. Also, the driver may modify the orientation of the reflection unit by a part other than a motor such as a solenoid, etc.
For example, the camera 87 is located at the +Z side and +X side of the user 14. However, the position of the camera is not limited to such a position as long as the eye of the user 14 can be imaged.
The controller 88 is electrically connected to the driver 86 and the camera 87. The controller 88 includes, for example, a processor such as a CPU (Central Processing Unit) or the like, memory such as ROM (Read Only Memory), RAM (Random Access Memory), etc. The controller 88 estimates the pupil position of the user 14 according to the image that is imaged by the camera 87. The controller 88 modifies the orientation of the reflection unit 12 by controlling the driver 86 according to the estimated pupil position.
For example, when the estimated pupil position is positioned at the −Z side or +Z side of the light reflected by the front windshield 13a, the controller 88 drives the first motor 86a to rotate the mirror 131 around the rotation axis D1. As a result, the irradiation position on the front windshield 13a of the light emitted from the mirror 131 can be modified along the Z-direction. Also, when the estimated pupil position is positioned at the −Y side or +Y side of the light reflected by the front windshield 13a, the controller 88 drives the second motor 86b to rotate the mirror 131 around the rotation axis D2. As a result, the irradiation position on the front windshield 13a of the light emitted from the mirror 131 can be modified along the Y-direction.
According to the embodiment as described above, the travel direction of the light emitted from the reflection unit 12 can be modified according to the pupil position of the user 14.
A ninth embodiment will now be described.
The location of the light source unit 11 of the image display device 90 according to the embodiment is different from that of the image display device 10 according to the first embodiment.
In the image display device 90, the light source unit 11 is located adjacent to the reflection unit 12 in the Y-direction. For example, the light source unit 11 and the reflection unit 12 are located at the dashboard part 13c. However, the light source unit and the reflection unit may be located at the ceiling part.
The X-direction in which the eyebox 14a and the inner surface of the front windshield 13a face each other is taken as the first direction, and the Z-direction that is orthogonal to the first direction is taken as the second direction. The light from the inner surface of the front windshield 13a toward the eyebox 14a is positioned at the XY-plane orthogonal to the second direction (the Z-direction). The light source unit 11 and the reflection unit 12 are located in a region at one side (the −Z side) in the second direction with the XY-plane as a boundary. In other words, the light source unit 11 and the reflection unit 12 are separated in the −Z direction from the XY-plane. However, at least one of the light source unit or the reflection unit and the light from the inner surface of the front windshield toward the eyebox may be positioned at the same XY-plane orthogonal to the second direction (the Z-direction). Here, the light source unit being positioned at the XY-plane means that a portion of the light source unit is positioned at the XY-plane. This is similar for the reflection unit as well.
A tenth embodiment will now be described.
The image display device 100 according to the embodiment can be mounted in the vehicle 130 and used as a HUD. In other words, an automobile 1000 according to the embodiment includes the vehicle 130 and the image display device 100. The image display device 100 is fixed to the vehicle 130. This is similar for other embodiments as well. The light source unit 11 of the image display device 100 is located at a ceiling part 130b of the vehicle 130. The reflection unit 12 of the image display device 100 is located at a dashboard part 130c of the vehicle 130.
The light source unit 11 that is located at the ceiling part 130b forms the first image IM1 between the light source unit 11 and the reflection unit 12. The reflection unit 12 reflects the light emitted from the light source unit 11. The greater part of the light reflected by the reflection unit 12 is reflected by the inner surface of a front windshield 130a and enters the eyebox of the user 14. As a result, the user 14 can view the second image IM2. The light source unit 11 also can be configured to have a continuous body with a rearview mirror unit (not illustrated), etc.
An eleventh embodiment will now be described.
The image display device 70A according to the embodiment differs from the image display device 10 according to the first embodiment in that a display device 710A is included instead of the display device 110, and a reflective polarizing element 740 is further included.
The display device 710A differs from the display device 710 (see
As shown in
According to the embodiment, the first polarized light 710p is P-polarized light, and the second polarized light 710s is S-polarized light. Herein, “P-polarized light” means light of which the oscillation direction of the electric field is substantially parallel to the XY-plane. Also, “S-polarized light” means light of which the oscillation direction of the electric field is substantially perpendicular to the XY-plane including the incident light and the reflected light.
There are cases where the user 14 of the vehicle 13 wears polarized sunglasses 14b to reduce glare such as sunlight reflected by a puddle in front of the vehicle 13 and transmitted by the front windshield 13a, etc. In such a case, the component corresponding to the P-polarized light of the sunlight reflected by the puddle or the like when reflected and viewed through the front windshield 13a is particularly reduced; therefore, the polarized sunglasses 14b are designed to shield the greater part of S-polarized light. Accordingly, when the user 14 wears the polarized sunglasses 14b, there is a possibility that the second image IM2 may be difficult for the user 14 to view because the polarized sunglasses 14b also undesirably shield the greater part of the S-polarized light included in the light emitted by the display device 710A. In the specification, P-polarized light and S-polarized light are physically defined by reflection objects such as the puddles and the like described above.
According to the embodiment, the reflective polarizing element 740 transmits the first polarized light 710p of the light emitted from the display device 710A and reflects the second polarized light 710s of the light emitted from the display device 710A. After traveling via the imaging optical system 120, the reflection unit 12, and the inner surface of the front windshield 13a, the greater part of the first polarized light 710p transmitted by the reflective polarizing element 740 enters the eyebox 14a without being shielded by the polarized sunglasses 14b. The incidence angle of the first polarized light 710p when incident on the inner surface of the front windshield 13a is set to a different angle from Brewster's angle.
Specifically, as shown in
The greater part of the first polarized light 710p included in the short-wavelength light and long-wavelength light is transmitted by the reflective polarizing element 740 and emitted from the imaging optical system 120.
Also, the greater part of the second polarized light 710s included in the short-wavelength light and long-wavelength light is reflected by the reflective polarizing element 740. Scattering reflection of a portion of the second polarized light 710s reflected by the reflective polarizing element 740 is performed by components of the display device 710A such as the light-scattering member 716A, the wavelength conversion member 715, etc. A portion of the second polarized light 710s is converted into the first polarized light 710p by the scattering reflection. A portion of the first polarized light 710p converted from the second polarized light 710s is transmitted by the reflective polarizing element 740 and emitted from a light source unit 71A. Therefore, the luminance of the first image IM1 can be increased while increasing the ratio of the first polarized light 710p included in the light emitted from the light source unit 71A. By improving the luminance of the first image IM1, the luminance of the second image IM2 also is improved. As a result, the user 14 more easily views the second image IM2.
Also, a portion of the short-wavelength light included in the second polarized light 710s may be reflected by the reflective polarizing element 740 and then incident on the wavelength conversion member 715. In such a case, an effect can be expected in which the wavelength conversion member 715 absorbs the short-wavelength light of the second polarized light 710s and radiates new long-wavelength light. Both the scattered reflection light and the radiated light have substantially Lambertian light distributions.
Also, the reflective polarizing element 740 itself may scatter and reflect the second polarized light 710s. In such a case as well, a portion of the second polarized light 710s is converted into the first polarized light 710p by the scattering reflection.
For example, a multilayer stacked thin film polarizing plate in which thin film layers of different polarization characteristics are stacked, etc., can be used as the reflective polarizing element 740.
According to the embodiment, one reflective polarizing element 740 covers all of the pixels of the display device 710A. However, the light source unit may include multiple reflective polarizing elements, and the reflective polarizing elements may be located respectively on the pixels. Also, the configuration of the display device used in combination with the reflective polarizing element is not limited to the configuration described above. For example, the display device may be configured without a light-scattering member by using the light scattering reflection effect of the wavelength conversion member. Also, the display device may be configured without a wavelength conversion member by using the scattering reflection effect of the light-scattering member. Also, the display device may be configured without a wavelength conversion member or a light-scattering member by using the light scattering reflection effect of multiple recesses or multiple protrusions provided in the light-emitting surface of the LED element as in the first embodiment.
Effects of the embodiment will now be described.
The light source unit 71A according to the embodiment further includes the reflective polarizing element 740 that is located on the display device 710A, transmits the first polarized light 710p of the light emitted from the display device 710A, and reflects the second polarized light 710s of the light emitted from the display device 710A. Therefore, the luminance of the first image IM1 can be increased while increasing the ratio of the first polarized light 710p included in the light emitted from the light source unit 71A.
Also, the light that is emitted from the reflective polarizing element 740 has a substantially Lambertian light distribution. Therefore, according to the embodiment as well, the light source unit 71A that is small and can form a high-quality first image IM1 can be provided. Because the multiple LED elements 712 are discretely mounted on the substrate 111, the first image IM1 may have a grainy appearance. The wavelength conversion member 715 has the effect of relaxing the grainy appearance. Also, the light-scattering member 716A can further reinforce the effect of relaxing the grainy appearance.
An image display device 70B according to the embodiment differs from the image display device 10 according to the first embodiment in that a light source unit 71B includes the display device 710A having a configuration similar to that of the eleventh embodiment instead of the display device 110, and a reflective polarizing element 750 and a light-shielding member 760 are further included. In
The reflective polarizing element 750 is located at a part of the optical path from the display device 710A to the reflection unit 12 at which the multiple chief rays L are substantially parallel to each other. According to the embodiment, the multiple chief rays L are substantially parallel to each other in the optical path between the intermediate element 122 and the reflection unit 12, and the reflective polarizing element 750 is located between the intermediate element 122 and the output element 123.
The reflective polarizing element 750 transmits the first polarized light 710p, which is P-polarized light, and reflects the second polarized light 710s, which is S-polarized light, to return the second polarized light 710s to the display device 710A. Specifically, the display device 710A emits light 710a that includes the first and second polarized light 710p and 710s. The light 710a travels via the input element 121 and the intermediate element 122 and then is incident on the reflective polarizing element 750.
The reflective polarizing element 750 transmits the greater part of the first polarized light 710p included in the light 710a. The greater part of the first polarized light 710p transmitted by the reflective polarizing element 750 travels via the output element 123 and then is emitted from the reflection unit 12.
The reflective polarizing element 750 reflects the greater part of the second polarized light 710s included in the light 710a and returns the greater part of the second polarized light 710s along the optical path from the display device 710A to the reflective polarizing element 750. Specifically, the reflective polarizing element 750 has a flat plate shape. The reflective polarizing element 750 is arranged to be substantially orthogonal to the chief rays L. The reflective polarizing element 750 specularly reflects the greater part of the second polarized light 710s. Therefore, the greater part of the second polarized light 710s reflected by the reflective polarizing element 750 travels via the intermediate element 122 and the input element 121 in this order and then returns to the display device 710A.
Similarly to the eleventh embodiment, a portion of the second polarized light 710s returning to the display device 710A is scattered and reflected by the components of the display device 710A such as the light-scattering member 716A, the wavelength conversion member 715, etc. A portion of the second polarized light 710s converted into the first polarized light 710p by the scattering reflection. A portion of the first polarized light 710p converted from the second polarized light 710s travels via the input element 121 and the intermediate element 122 and then is transmitted by the reflective polarizing element 750. The greater part of the first polarized light 710p transmitted by the reflective polarizing element 750 travels via the output element 123 and then is emitted from the reflection unit 12. Therefore, the luminance of the second image IM2 can be increased while increasing the ratio of the first polarized light 710p included in the light emitted from the image display device 70B. As a result, the user 14 more easily views the second image IM2.
Also, similarly to the eleventh embodiment, a portion of the short-wavelength light included in the second polarized light 710s returning to the display device 710A may be irradiated on the wavelength conversion member 715. In such a case as well, similarly to the eleventh embodiment, the wavelength conversion member 715 absorbs the short-wavelength light of the second polarized light 710s, and an effect of radiating new long-wavelength light can be expected.
The reflective polarizing element 750 can include, for example, a wire-grid reflective polarizing element using multiple metal nanowires.
The light-shielding member 760 is located between the display device 710A and the input element 121 of the imaging optical system 120. For example, the light-shielding member 760 has a flat plate shape substantially parallel to the XY-plane. An aperture 761 that extends through the light-shielding member 760 in the Z-direction is provided in the light-shielding member 760. The focal point F of the imaging optical system 120 is positioned inside the aperture 761.
The light emitted from the display device 710A and passing through the focal point F and the vicinity of the focal point F passes through the aperture 761 of the light-shielding member 760 and is incident on the input element 121, and the greater part of the light other than the light passing through the aperture 761 is shielded by the light-shielding member 760. Also, the second polarized light 710s that is reflected by the reflective polarizing element 750 and travels along the optical path, i.e., the light that passing through the focal point F and the vicinity of the focal point F, passes through the aperture 761 of the light-shielding member 760 and returns to the display device 710A. On the other hand, the greater part of the second polarized light 710s that is reflected by the reflective polarizing element 750 and travels toward the display device 710A and not along the optical path is shielded by the light-shielding member 760.
Effects of the embodiment will now be described.
The image display device 70B according to the embodiment further includes the reflective polarizing element 750. The reflective polarizing element 750 is located at a part of the optical path from the display device 710A to the reflection unit 12 at which the multiple chief rays L that are emitted from mutually-different positions of the display device 710A and pass through the first image IM1 are substantially parallel to each other, transmits the first polarized light 710p of the light emitted from the display device 710A, and reflects the second polarized light 710s of the light emitted from the display device 710A to return the second polarized light 710s to the display device 710A. Therefore, the luminance of the second image IM2 can be increased while increasing the ratio of the first polarized light 710p included in the light emitted from the image display device 70B.
Also, the light-shielding member 760 is located between the display device 710A and the input element 121. The aperture 761 that transmits the second polarized light 710s returning to the display device 710A along the optical path is provided in the light-shielding member 760. Therefore, the second polarized light 710s that is reflected by the reflective polarizing element 750, does not travel along the optical path, and becomes stray light can be prevented from traveling toward the display device 710A while permitting the second polarized light 710s that is reflected by the reflective polarizing element 750 and travels along the optical path to return to the display device 710A. The quality of the first and second images IM1 and IM2 can be increased thereby. Also, the light that is emitted from the display device 710A, does not travel along the optical path, and becomes stray light can be prevented by the light-shielding member 760 from being reflected by the reflective polarizing element 750 and/or optical elements of the imaging optical system 120, traveling toward the display device 710A, and being re-excited and/or scattered and reflected at unexpected locations.
The position of the reflective polarizing element 750 is not limited to the position shown in
Also, the light-shielding member 760 may not be included in the image display device 70B. Also, according to the eleventh embodiment, the reflective polarizing element 740 may be further provided on the display device 710A of the image display device 70B. In such a case, the second polarized light 710s that could not be reflected by the reflective polarizing element 740 on the display device 710A can be reflected by the reflective polarizing element 750. Therefore, the luminance of the second image IM2 can be increased while increasing the ratio of the first polarized light 710p included in the light emitted from the image display device 70B.
A thirteenth embodiment will now be described.
The light source unit 80A according to the embodiment includes the display device 710A similar to that of the eleventh embodiment, the reflective polarizing element 740 similar to that of the eleventh embodiment, an imaging optical system 820, a reflective polarizing element 871, a first waveplate 880, and a second waveplate 890. The display device 710A, the reflective polarizing element 871, the first waveplate 880, and the imaging optical system 820 are arranged in the X-direction in this order. However, the direction in which the display device, the reflective polarizing element, the first waveplate, and the imaging optical system are arranged is not particularly limited to the X-direction.
According to the embodiment, the display device 710A is arranged so that the light-emitting surface of the display device 710A faces the +X direction. However, the orientation of the display device is not limited to such an orientation.
The reflective polarizing element 740 is located on the display device 710A. According to the embodiment, the reflective polarizing element 740 transmits the first polarized light 710p, which is the P-polarized light emitted from the display device 710A, and reflects the second polarized light 710s, which is the S-polarized light emitted from the display device 710A, toward the display device 710A.
The imaging optical system 820 is made of one mirror 821. The mirror 821 includes a concave mirror surface 821a. The mirror 821 reflects the light emitted from the display device 710A and forms the first image IM1 corresponding to the image displayed by the display device 710A. The mirror 821 is substantially telecentric at the first image IM1 side. In other words, multiple chief rays L7 that are emitted from mutually-different positions on the display device 710A and reach the first image IM1 cross each other at a focal point F3 between the display device 710A and the mirror 821. Also, the multiple chief rays L7 that are emitted from the mirror 821 are substantially parallel to each other.
The reflective polarizing element 871 is located between the display device 710A and the mirror 821. The reflective polarizing element 871 transmits the first polarized light 710p and reflects the second polarized light 710s. For example, the reflective polarizing element 871 can include a beam splitter. For example, the reflective polarizing element 871 has a flat plate shape. For example, the reflective polarizing element 871 is tilted in the +X direction toward the +Z direction. However, the shape and orientation of the reflective polarizing element are not limited to such a shape and orientation.
The first waveplate 880 is located between the reflective polarizing element 871 and the mirror 821. According to the embodiment, the first waveplate 880 is a quarter-wave plate. The first waveplate 880 has a flat plate shape. For example, the first waveplate 880 is arranged to be substantially orthogonal to the chief rays L7 reflected by the mirror 821. In other words, the first waveplate 880 is arranged to be substantially parallel to the YZ-plane. However, the orientation of the first waveplate is not limited to such an orientation. For example, the first waveplate may be tilted with respect to a plane orthogonal to the chief rays reflected by the mirror.
The second waveplate 890 is located at the-Z side of the first waveplate 880. According to the embodiment, the second waveplate 890 is a half-wave plate. The second waveplate 890 has a flat plate shape. For example, the second waveplate 890 is arranged to be substantially orthogonal to the chief rays L7 that are reflected by the mirror 821, transmitted by the first waveplate 880, and then reflected by the reflective polarizing element 871. Accordingly, the second waveplate 890 is arranged to be tilted in the +X direction toward the +Z direction. However, the orientation of the second waveplate is not limited to such an orientation. For example, the second waveplate may be tilted with respect to a plane orthogonal to the chief rays.
The greater part of the first polarized light 710p of the light emitted from the display device 710A is transmitted by the reflective polarizing element 740, and the greater part of the second polarized light 710s of the light emitted from the display device 710A is reflected by the reflective polarizing element 740 and returns to the display device 710A.
The greater part of the first polarized light 710p transmitted by the reflective polarizing element 740 is transmitted by the reflective polarizing element 871 and then incident on the first waveplate 880. The first waveplate 880 is arranged to convert the greater part of the incident first polarized light 710p into a circularly polarized light 710c. The greater part of the circularly polarized light 710c emitted from the first waveplate 880 is reflected by the mirror surface 821a of the mirror 821.
The greater part of the circularly polarized light 710c reflected by the mirror surface 821a is incident on the first waveplate 880. The first waveplate 880 converts the greater part of the incident circularly polarized light 710c into the second polarized light 710s. The greater part of the second polarized light 710s emitted from the first waveplate 880 is reflected by the reflective polarizing element 871 toward the formation position P of the first image IM1.
The greater part of the second polarized light 710s reflected by the reflective polarizing element 871 is incident on the second waveplate 890. The second waveplate 890 is arranged to convert the greater part of the incident second polarized light 710s into the first polarized light 710p.
Effects of the embodiment will now be described.
The light source unit 80A according to the embodiment includes the display device 710A configured to display an image, the mirror 821 reflecting the light emitted from the display device 710A to form the first image IM1 corresponding to the image, the reflective polarizing element 871 located between the display device 710A and the mirror 821, and the first waveplate 880 located between the reflective polarizing element 871 and the mirror 821. The reflective polarizing element 871 transmits the first polarized light 710p of the light emitted from the display device 710A. The first waveplate 880 converts the first polarized light 710p transmitted by the reflective polarizing element 871 into the circularly polarized light 710c. The mirror 821 reflects, toward the first waveplate 880, the circularly polarized light 710c emitted from the first waveplate 880. The first waveplate 880 converts the circularly polarized light 710c reflected by the mirror 821 into the second polarized light 710s. The reflective polarizing element 871 reflects, toward the formation position P of the first image IM1, the second polarized light 710s emitted from the first waveplate 880.
The mirror 821 is substantially telecentric at the first image IM1 side, and the light that is emitted from the display device 710A has a substantially Lambertian light distribution. Therefore, according to the embodiment as well, the light source unit 80A that is small and can display a high-quality image can be provided.
Also, the light source unit 80A can be even smaller because the first image IM1 can be formed by one mirror 821.
Also, because the light reflected by the mirror 821 is reflected toward the formation position P of the first image IM1 by the reflective polarizing element 871 located between the display device 710A and the mirror 821, the light source unit 80A can be even smaller while forming the first image IM1 at the desired formation position P.
Also, the light source unit 80A further includes the second waveplate 890 that converts the second polarized light 710s reflected by the reflective polarizing element 871 into the first polarized light 710p. Therefore, the ratio of the first polarized light 710p included in the light emitted from the light source unit 80A can be increased.
Also, the light source unit 80A further includes the reflective polarizing element 740 that is located on the display device 710A, transmits the first polarized light 710p of the light emitted from the display device 710A, and reflects, toward the display device 710A, the second polarized light 710s of the light emitted from the display device 710A. Therefore, the luminance of the first image IM1 can be increased while increasing the ratio of the first polarized light 710p included in the light emitted from the light source unit 80A.
As shown in
A fourteenth embodiment will now be described.
The light source unit 80B according to the embodiment differs from the light source unit 80A according to the thirteenth embodiment in that a reflective polarizing element 840 is included instead of the reflective polarizing element 740, a reflective polarizing element 872 is included instead of the reflective polarizing element 871, and the second waveplate 890 is not included.
The reflective polarizing element 840 is located on the display device 710A. According to the embodiment, the reflective polarizing element 840 transmits a first polarized light 810s, which is the S-polarized light emitted from the display device 710A, and reflects, toward the display device 710A, a second polarized light 810p, which is the P-polarized light emitted from the display device 710A.
The reflective polarizing element 872 is located between the display device 710A and the mirror 821. The reflective polarizing element 872 transmits the first polarized light 810s, which is the S-polarized light, and reflects the second polarized light 810p, which is the P-polarized light. The reflective polarizing element 872 can include, for example, a beam splitter. For example, the reflective polarizing element 872 has a flat plate shape. For example, the reflective polarizing element 872 is tilted in the +X direction toward the +Z direction. However, the shape and orientation of the reflective polarizing element are not limited to such a shape and orientation.
The greater part of the first polarized light 810s of the light emitted from the display device 710A is transmitted by the reflective polarizing element 840, and the greater part of the second polarized light 810p of the light emitted from the display device 710A is reflected by the reflective polarizing element 840 and returns to the display device 710A.
The greater part of the first polarized light 810s transmitted by the reflective polarizing element 840 is transmitted by the reflective polarizing element 872 and incident on the first waveplate 880. The first waveplate 880 converts the greater part of the incident first polarized light 810s into the circularly polarized light 710c. The greater part of the circularly polarized light 710c emitted from the first waveplate 880 is reflected by the mirror surface 821a of the mirror 821.
The greater part of the circularly polarized light 710c reflected by the mirror surface 821a is incident on the first waveplate 880. The first waveplate 880 converts the greater part of the incident circularly polarized light 710c into the second polarized light 810p. The greater part of the second polarized light 810p emitted from the first waveplate 880 is reflected by the reflective polarizing element 872 toward the formation position P of the first image IM1.
Effects of the embodiment will now be described.
In the light source unit 80B according to the embodiment, the reflective polarizing element 872 transmits the first polarized light 810s, which is S-polarized light, and reflects the second polarized light 810p, which is P-polarized light. It is therefore unnecessary to include the second waveplate 890 of the thirteenth embodiment. Therefore, the light source unit 80B can be small while increasing the ratio of the P-polarized light included in the light emitted from the light source unit 80B.
As shown in
The light source units 80A and 80B described above are applicable to an image display device in combination with the reflection unit 12. Also, such an image display device is applicable to a head-up display.
Examples are described in the eleventh to fourteenth embodiments in which the ratio of the P-polarized light included in the light emitted from the light source unit or the image display device is increased. However, according to the eleventh to fourteenth embodiments described above, the ratio of the S-polarized light included in the light emitted from the light source unit or the image display device may be increased by reversing the P-polarized light and the S-polarized light. S-polarized light is easily reflected by the inner surface of the front windshield 13a. Therefore, for example, in an environment in which the frequency of use of the polarized sunglasses 14b is low, the user 14 can more easily view the second image IM2 by increasing the ratio of the S-polarized light included in the light emitted from the light source unit or the image display device.
Modifications of the display device 110 of the light source unit 11 according to the first embodiment will now be described.
As shown in
In a display device 110B as shown in
As shown in
For easier understanding of the description in
As shown in
The light-shielding member 117C may include a resin member and light-reflective particles located inside the resin member, and may shield by reflecting the light. Also, the light-shielding member 117C may include a resin member and light-absorbing particles located inside the resin member, and may shield by absorbing the light. The resin member can include a thermosetting resin such as a silicone resin, an epoxy resin, etc. The light-reflective particles can include silicon oxide (SiO2), titanium oxide (TiO2), aluminum (Al), silver (Ag), etc. Carbon particles made of carbon powder, etc., can be used as the light-absorbing particles. This is similar for other light-shielding members described below as well.
Also, as shown in
Also, as shown in
As shown in
As shown in
Also, as shown in
Also, as shown in
In a display device 110E as shown in
As shown in
As shown in
Hereinbelow, an LED element that emits blue light also is called a “blue LED element,” an LED element that emits green light also is called a “green LED element,” and an LED element that emits red light also is called a “red LED element.” Also, a wavelength conversion substance that emits yellow light also is called a “yellow wavelength conversion substance,” a wavelength conversion substance that emits green light also is called a “green wavelength conversion substance,” and a wavelength conversion substance that emits red light also is called a “red wavelength conversion substance.” Herein, blue light is, for example, light having a light emission peak wavelength of not less than 450 nm and not more than 495 nm. Yellow light is, for example, light having a light emission peak wavelength of not less than 570 nm and not more than 620 nm. Green light is, for example, light having a light emission peak wavelength of not less than 495 nm and not more than 570 nm. Red light is, for example, light having a light emission peak wavelength of not less than 620 nm and not more than 750 nm. Yellow light also can be obtained by mixed light of green light and red light.
According to the modifications described with reference to
Also, the LED element may include a semiconductor stacked body in which a first n-type semiconductor layer, a first active layer, a first p-type semiconductor layer, a second n-type semiconductor layer, a second active layer, and a second p-type semiconductor layer are stacked, and the light emission peak wavelength of the light emitted by the first active layer and the light emission peak wavelength of the light emitted by the second active layer may be different. Hereinbelow, such an LED element is called a two-color LED element. The LED element may be a two-color LED element of blue light and green light, and the wavelength conversion member may include a red wavelength conversion substance.
Also, a blue LED element and a green LED element may be located in one pixel, and a wavelength conversion member that includes a red wavelength conversion substance may be located on the blue LED element and the green LED element. Similarly, a blue LED element and a red LED element may be located in one pixel, and a wavelength conversion member that includes a green wavelength conversion substance may be located on the blue LED element.
The wavelength conversion member may include a light-transmitting resin member, and a wavelength conversion substance located inside the resin member. Also, the wavelength conversion member may be a sintered body of a wavelength conversion substance. Also, the wavelength conversion member may have a sheet-like shape, layer shape, or plate shape.
The wavelength conversion substance can include an yttrium-aluminum-garnet-based fluorescer (e.g., Y3(Al, Ga)5O12: Ce), a lutetium-aluminum-garnet-based fluorescer (e.g., Lu3(Al, Ga)5O12: Ce), a terbium-aluminum-garnet-based fluorescer (e.g., Tb3(Al, Ga)5O12: Ce), a CCA-based fluorescer (e.g., Ca10(PO4)6Cl2: Eu), an SAE-based fluorescer (e.g., Sr4Al14O25: Eu), a chlorosilicate-based fluorescer (e.g., Ca8MgSi4O16Cl2: Eu), an oxynitride-based fluorescer such as a β-sialon-based fluorescer (e.g., (Si, Al)3(O, N)4: Eu), an α-sialon-based fluorescer (e.g., Ca(Si, Al)12(O, N)16: Eu), or the like, a nitride-based fluorescer such as an SLA-based fluorescer (e.g., SrLiAl3N4: Eu), a CASN-based fluorescer (e.g., CaAlSiN3: Eu), a SCASN-based fluorescer (e.g., (Sr, Ca)AlSiN3: Eu), or the like, a fluoride-based fluorescer such as a KSF-based fluorescer (e.g., K2SiF6: Mn), a KSAF-based fluorescer (e.g., K2Si0.99Al0.01F5.99: Mn), a MGF-based fluorescer (e.g., 3.5 MgO·0.5 MgF2·GeO2: Mn), or the like, a fluorescer having a perovskite structure (e.g., CsPb(F, Cl, Br, I)3), a quantum dot fluorescer (e.g., CdSe, InP, AgInS2, or AgInSe2), etc.
White light can be emitted from each pixel by combining any of the LED elements and wavelength conversion members described above. However, the color of the light emitted from each pixel is not limited to white.
In
As shown in
Also, as shown in
Also, as shown in
As shown in
As shown in
As shown in
As shown in
As shown in
As shown in
As shown in
The display device 110F can display a color image by any of the configurations described above. The number of blue LED elements and the number and arrangement of green LED elements, red LED elements, and/or two-color LED elements located in one pixel are not limited to those described above. Also, the areas of the light-emitting surfaces of the different types of LED elements may be the same, and the areas of the light-emitting surfaces of two or more types of LED elements may be different from each other.
In the display device 110H, the multiple LED elements 112H may be formed on one growth substrate 119H. The growth substrate 119H is, for example, a light-transmitting sapphire substrate. Also, a wavelength conversion member 115H may be located around the LED element 112H and/or on the growth substrate 119H.
The display device 110I may include multiple growth substrates 119I, and the multiple LED elements 112I may be formed on each growth substrate 119I. Also, a wavelength conversion member 115I may be located around the LED element 112I and/or on the multiple growth substrates 119I.
As shown in
A fifteenth embodiment will now be described.
The automobile 1000 includes the vehicle 13, and an image display device 20 fixed to the vehicle 13. The image display device 20 includes the light source unit 11 and a reflection unit 22. The image display device 20 according to the embodiment differs from the image display device 10 according to the first embodiment in that a mirror surface 322a of a mirror 322 of the reflection unit 22 also is used as a reflecting surface causing the user 14 to view the second image IM2.
The configuration of the light source unit 11 of the image display device 20 is similar to that of the first embodiment. The light source unit 11 is located at the ceiling part 13b of the vehicle 13. The reflection unit 22 is located at the dashboard part 13c of the vehicle 13. The reflection unit 22 includes the mirror 322. The mirror surface 322a of the mirror 322 is, for example, a concave surface. The mirror surface 322a is arranged at a position and angle facing the eyebox 14a of the user 14 when the user 14 is in the driver's seat of the vehicle 13. For example, the mirror surface 322a faces a direction between the −X direction (the back side of the vehicle) and the +Z direction (the upper side of the vehicle). The angle of the mirror surface 322a can be finely adjusted according to the position of the eyebox 14a of the user 14.
An operation of the embodiment will now be described.
Chief rays L8 that are emitted from the light source unit 11 travel in a direction between the +X direction (the front side of the vehicle) and the −Z direction (the lower side of the vehicle), are reflected by the mirror surface 322a of the mirror 322 of the reflection unit 22, travel in a direction between the −X direction (the back side of the vehicle) and the +Z direction (the upper side of the vehicle), and enter the eyebox 14a of the user 14. The path of the chief rays L8 from the light source unit 11 toward the reflection unit 12 is positioned inward of the front windshield 13a of the vehicle 13 and is substantially along the front windshield 13a. The chief rays L8 form the first image IM1 at a position P between the light source unit 11 and the reflection unit 22.
As a result, as shown in
Effects of the embodiment will now be described.
Similarly to the first embodiment, the image display device 20 according to the embodiment is divided into the two units of the light source unit 11 and the reflection unit 22 fixed at separate positions in the vehicle 13. Although the image display device 20 requires a long optical path length to form the second image IM2 at a position several meters frontward, by separating the light source unit 11 and the reflection unit 22, a portion of the optical path length can be formed by utilizing the internal space of the vehicle 13. As a result, it is unnecessary to form the necessary optical path length entirely inside the image display device 20, and the image display device 20 can be smaller.
Also, in the image display device 20, the reflection unit 22 includes only the mirror 322. The configuration of the reflection unit 22 can be simplified thereby, and the reflection unit 22 can be smaller. Otherwise, the configuration, operations, and effects according to the embodiment are similar to those of the first embodiment.
The mirror 322 of the reflection unit 22 may include a half mirror or a transparent plate. In such a case as well, the user 14 can be prevented from undesirably viewing the interior of the dashboard part 13c by making the interior of the dashboard part 13c dark. Or, the mirror surface 322a of the mirror 322 may be black enough to sufficiently reflect the chief rays L8 emitted from the light source unit 11. As a result, degradation of the visibility due to external light or the like reflected by the mirror surface 322a of the mirror 322 can be suppressed. Also, the mirror 322 may be arranged to be continuous with the surface of the dashboard part 13c. As a result, it is unnecessary to make a hole in the dashboard part 13c, and the designability of the interior of the automobile 1000 is improved.
Also, instead of the mirror surface 322a located at the dashboard part 13c, the front windshield 13a or a combiner may be used as the reflecting surface causing the user 14 to view the second image IM2. However, by using the mirror surface 322a located at the dashboard part 13c as the reflecting surface, the user 14 can reliably view the second image IM2 without being affected by the background of the reflecting surface.
A sixteenth embodiment will now be described.
The image display device 30 according to the embodiment differs from the image display device 10 according to the first embodiment in that three units located at different positions in the vehicle 13 are included. Namely, the image display device 30 includes a light source unit 91, an optical path modifying unit 32, and the reflection unit 22.
For example, the light source unit 91 is located inside an A-pillar 13d or at the backside of a car navigation device 13e of the vehicle 13 shown in
The light source unit 91 includes the display device 110, an input element 621, and an output element 631. The configuration of the display device 110 is as described in the first embodiment. The input element 621 and the output element 631 are, for example, concave mirrors.
The optical path modifying unit 32 includes a mirror 332. The mirror 332 may be a plane mirror, may be a concave mirror, or may be a convex mirror. The type of mirror used as the mirror 332 is set according to how the optical path of the image display device 30 is set inside the vehicle 13. The configuration of the reflection unit 22 is similar to that of the reflection unit 22 of the fifteenth embodiment.
As shown in
An operation of the embodiment will now be described.
In the following description, it is taken that the driver's seat is located at the right side of the vehicle 13, and the light source unit 91 is located inside the A-pillar 13d.
Chief rays L9 that are emitted from the light source unit 91 travel in the −X direction (the back side of the vehicle), the +Z direction (the upper side of the vehicle) and the +Y direction (the left side of the vehicle), form the first image IM1 at the position P between the light source unit 91 and the optical path modifying unit 32, and reach the mirror 332 of the optical path modifying unit 32.
The chief rays L9 that are incident on the mirror 332 are reflected by the mirror surface 332a, travel in a direction between the +X direction (the front side of the vehicle) and the −Z direction (the lower side of the vehicle), are reflected by the mirror surface 322a of the mirror 322 of the reflection unit 22, travel in a direction between the −X direction (the back side of the vehicle) and the +Z direction (the upper side of the vehicle), and enter the eyebox 14a of the user 14. The path of the chief rays L9 from the optical path modifying unit 32 toward the reflection unit 12 is positioned inward of the front windshield 13a of the vehicle 13 and is substantially along the front windshield 13a.
As a result, the user 14 can view the second image IM2 depthward of the mirror surface 322a of the dashboard part 13c. The appearance of the second image IM2 is similar to that of the fifteenth embodiment.
Effects of the embodiment will now be described.
The image display device 30 according to the embodiment is subdivided into the three units of the light source unit 91, the optical path modifying unit 32, and the reflection unit 22; therefore, each unit can be smaller. As a result, the arrangement of the image display device 30 in the vehicle 13 is even easier.
In particular, the volume of the optical path modifying unit 32 located at the ceiling part 13b can be greatly reduced because the optical path modifying unit 32 can include mainly the mirror 332. The mirror 332 may be a portion of the ceiling board of the ceiling part 13b. Also, the volume of the reflection unit 22 located at the dashboard part 13c can be greatly reduced because the reflection unit 22 also can include mainly the mirror 322. Furthermore, because the light source unit 91 that has a relatively large volume can be located inside the A-pillar 13d or at the backside of the car navigation device 13e in the vehicle 13, the dead space of the vehicle 13 can be effectively utilized. Otherwise, the configuration, operations, and effects according to the embodiment are similar to those of the first embodiment.
A seventeenth embodiment will now be described.
Similarly to the image display device 30 according to the sixteenth embodiment, the image display device 40 according to the embodiment includes three units. The image display device 40 differs from the image display device 30 in that the front windshield 13a is utilized as a reflecting surface causing the user 14 to view the second image IM2. The image display device 40 includes the light source unit 91, the optical path modifying unit 32, and the reflection unit 12.
For example, the light source unit 91 is located inside the A-pillar 13d of the vehicle 13 or at the backside of the car navigation device 13e. The configuration of the light source unit 91 is as described in the sixteenth embodiment. For example, the optical path modifying unit 32 is located at the ceiling part 13b of the vehicle 13. The configuration of the optical path modifying unit 32 is as described in the sixteenth embodiment. For example, the reflection unit 12 is located at the dashboard part 13c of the vehicle 13. The configuration of the reflection unit 12 is as described in the first embodiment.
The light source unit 91 is not visible to the user 14 sitting on the driver's seat. The mirror 332 of the optical path modifying unit 32 and the mirror 131 of the reflection unit 12 may be visible or may not be visible to the user 14 sitting on the driver's seat. It is favorable for the mirror 332 and the mirror 131 not to be visible to the user 14 to improve the designability of the interior of the automobile 1000.
An operation of the embodiment will now be described.
The chief rays L9 that are emitted from the light source unit 91 form the first image IM1 at the position P, subsequently are reflected by the mirror surface 332a of the mirror 332 of the optical path modifying unit 32, and reach the reflection unit 12. The trajectory of the chief rays L9 from the light source unit 91 to the reflection unit 12 is similar to that of the sixteenth embodiment. The chief rays L9 that reached the reflection unit 12 are reflected by the mirror surface 131a of the mirror 131 of the reflection unit 12, travel in substantially the +Z direction (the upper side of the vehicle), and reach the front windshield 13a. The chief rays L9 that reached the front windshield 13a are reflected by the inner surface of the front windshield 13a, travel in the −X direction (the back side of the vehicle), and enter the eyebox 14a of the user 14.
As a result, the user 14 can view the second image IM2, which is a virtual image, beyond the front windshield 13a. For example, the second image IM2 is viewed at a position 3 m in front of the front windshield 13a.
Effects of the embodiment will now be described.
According to the embodiment as well, similarly to the sixteenth embodiment, the image display device 40 is subdivided into the three units of the light source unit 91, the optical path modifying unit 32, and the reflection unit 12; therefore, each unit can be smaller. Otherwise, the configuration, operations, and effects according to the embodiment are similar to those of the sixteenth embodiment.
The configurations of the multiple embodiments and multiple modifications described above can be combined as appropriate to the extent of technical feasibility.
As described above, the arrangement of the light source unit and the reflection unit can be set freely as long as the first image can be formed between the light source unit and the reflection unit, and the light emitted from the reflection unit can be irradiated on the reflecting surfaces such as the inner surface of the front windshield, etc.
For example, the invention can be utilized in a head-up display.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2021-154371 | Sep 2021 | JP | national |
| 2021-189574 | Nov 2021 | JP | national |
This is a national stage application of PCT Application No. PCT/JP2022/016758, filed on Mar. 31, 2022, which claims priority to Japanese Patent Application No. 2021-154371, filed on Sep. 22, 2021 and Japanese Patent Application No. 2021-189574, filed on Nov. 22, 2021.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2022/016758 | 3/31/2022 | WO |
