Display unit

Abstract

To provide a display unit that can employ a structure to rotate a polarization selection module to have better mountability into an instrumental panel and easily switch between a real image and a virtual image.SOLUTION: A display unit has: a display 10 that emits light from a light source 111 as P-polarized light and displays a display image; a polarization selection module 20 that reflects S-polarized light and transmits the P-polarized light; a rotation driving unit 21 that causes the polarization selection module 20 to rotate around a rotation axis S; and a control unit 30 that controls the rotation driving unit 21, and comprises: a first mirror 11 that is provided at a first angle position along a circumferential direction around the rotation axis S; and a second mirror 12 that is provided at a second angle position. When causing a viewer to view a real image RI, the display unit rotates the polarization selection module 20 to a first rotation position for displaying a real image RI, and when causing the viewer to view a virtual image VI, rotates the polarization selection module 20 to a second rotation position for displaying a virtual image VI.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a display device that provides a desired display to a viewer. [Background technology]

[0002] A display device described in Patent Document 1, for example, is known from the past. This display device is installed in a vehicle and has an optical system that forms a real image in front of the viewer and an optical system that forms a virtual image, and by switching between these, the viewer can see the display at different display distances. Specifically, the virtual image is perceived as being outside the vehicle, and the real image is perceived as being inside the vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-70074 Summary of the Invention [Problem to be solved by the invention]

[0004] However, for example, when it is desired to view a display image without using a front window (windshield) as shown in Patent Document 1, it is necessary to complete the optical system within the instrument panel, and when displaying a real image or a virtual image, it is necessary to increase the optical path length, which leads to an increase in the size of the entire device and reduces the ease of installation within the instrument panel.

[0005] Therefore, the present invention has been made in consideration of the above problems, and aims to provide a display device that can easily switch between real and virtual images while improving the mountability of the device within an instrument panel by adopting a structure that rotates the polarization selection module. [Means for solving the problem]

[0006] The present invention relates to a display device 1 that is provided in an instrument panel IP of a vehicle C, and that emits display light L from an emission port 17 to allow a virtual image VI and a real image RI of a display image represented by the display light L to be visually recognized. The display device 1 includes a light source 111, a display unit 10 that emits light from the light source 111 with a first linearly polarized light and displays the display image, a polarization selection module 20 that reflects a second linearly polarized light that is orthogonal to the first linearly polarized light and transmits the first linearly polarized light, a rotation drive unit 21 that rotates the polarization selection module 20 around a rotation axis S so that an angle with respect to an optical path is variable, a control unit 30 that controls the rotation drive unit 21, and a first mirror 11 and a second mirror 12 that are arranged at positions to reflect the display light L to the polarization selection module 20, the first mirror 11 being arranged at a first angular position along a circumferential direction around the rotation axis S, and the second mirror 12 being arranged at a different angular position from the first angular position. The control unit 30 controls the rotation drive unit 21 to rotate the polarization selection module 20 to a first rotation position for displaying a real image RI, where, when the real image RI is to be viewed, the display light L emitted from the display unit 10 is transmitted, the display light L reflected by the first mirror 11 is incident, and then the direction of the reflected and emitted display light L is toward the second mirror 12, and the direction of the display light L after the display light L reflected by the second mirror 12 is transmitted is toward the exit 17; and when the virtual image VI is to be viewed, the control unit 30 controls the rotation drive unit 21 to rotate the polarization selection module 20 to a second rotation position for displaying a virtual image VI, where the display light L emitted from the display unit 10 is transmitted, the display light L reflected by the first mirror 11 is incident, and then the direction of the reflected and emitted display light L is toward the exit 17 without passing through the second mirror 12. [Effects of the Invention]

[0007] According to the present invention, the mountability within the instrument panel is improved, and it is possible to easily switch between a real image and a virtual image without using a windshield. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing how a viewer views a real image in a display device according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing how a viewer views a virtual image in the display device according to the first embodiment of the present invention. [Figure 3] FIG. 2 is a diagram showing a layout when a real image is viewed in the display device according to the first embodiment of the present invention. [Figure 4] FIG. 2 is a diagram showing a layout when a virtual image is visually recognized in the display device according to the first embodiment of the present invention. [Figure 5] 1 is a diagram showing the configuration of a display unit in a display device according to a first embodiment of the present invention. [Figure 6] 1 is a diagram showing the structure of a polarization selection module in a display device according to a first embodiment of the present invention. [Figure 7] 3A and 3B are diagrams illustrating the transition of the polarization state of display light when a real image is viewed in the display device according to the first embodiment of the present invention. [Figure 8] 3A and 3B are diagrams illustrating the transition of the polarization state of display light when a virtual image is viewed in the display device according to the first embodiment of the present invention. [Figure 9] FIG. 10 is a diagram showing the structures of a polarization selection module, a first mirror, and a second mirror in a display device according to a second embodiment of the present invention. [Figure 10] 10A and 10B are diagrams illustrating the transition of the polarization state of display light when a real image is viewed in a display device according to a second embodiment of the present invention. [Figure 11] 10A and 10B are diagrams illustrating the transition of the polarization state of display light when a virtual image is viewed in a display device according to a second embodiment of the present invention. [Figure 12] FIG. 10 is a diagram illustrating a system capable of displaying a real image in a display device according to another embodiment of the present invention, rearranged into a coaxial system. [Figure 13] FIG. 10 is a diagram illustrating a system capable of displaying a virtual image in a display device according to another embodiment of the present invention, rearranged into a coaxial system. [Figure 14] FIG. 10 is a diagram showing an example of the configuration of a display device according to another embodiment of the present invention when a lens is inserted in the optical path of display light. [Figure 15] FIG. 1 is a diagram showing the configuration of a doublet lens. DETAILED DESCRIPTION OF THE INVENTION

[0009] (First embodiment of the present invention) A display device according to the present embodiment will be described with reference to the drawings. FIG. 1 is a diagram showing how a viewer views a real image on the display device according to the present embodiment, and FIG. 2 is a diagram showing how a viewer views a virtual image on the display device according to the present embodiment. In FIGS. 1 and 2, the display device 1 is mounted in an instrument panel IP (hereinafter referred to as instrument panel IP) installed at the front of the interior of a vehicle C, and includes a display unit 10 that displays a display image to be viewed by a viewer PS, a polarization selection module 20 that transmits first linearly polarized light from the display unit 10 and reflects second linearly polarized light orthogonal to the first linearly polarized light, and rotates around a rotation axis S so that the angle with respect to the optical path is variable, and a control unit 30 that controls the display mode of the display unit 10 and also controls the rotation angle of the polarization selection module 20. The display light L emitted from the display unit 10 passes through the polarization selection module 20 and mirrors (first mirror 11, second mirror 12) described below and is emitted from an opening (exit) 17 in the instrument panel IP, and the display light L is directed to a viewer PS who is seated inside the vehicle facing the instrument panel IP, allowing the viewer PS to view the display image represented by the display light L.

[0010] FIG. 1 shows a state in which the viewer PS views a real image RI as if it were floating in front of an instrument panel IP (between the viewer PS and the instrument panel IP). The specific display distance is, for example, about 500 mm to 800 mm from the eye position. For example, an operation screen or the like is displayed as the real image RI when the system is started up or when a gesture by the viewer PS is detected. FIG. 2 shows a state in which the viewer PS views a virtual image VI as if it were embedded in the depths of the instrument panel IP. The specific display distance is, for example, about 2 m to 3 m from the eye position. For example, entertainment content such as a movie or game selected by the viewer PS is displayed as the real image RI as the virtual image VI. Thereafter, the real image RI is switched to when the content ends or when a gesture by the viewer PS is detected.

[0011] The viewer PS includes the driver of vehicle C and the person sitting in the passenger seat, and the instrument panel IP refers to the entire front area of ​​the vehicle interior (for example, the area in front of the driver's seat where instruments are located, the area between the driver's seat and the passenger seat where displays and equipment are located, and the dashboard area in front of the passenger seat).

[0012] In addition, the optimal display position and display size of the real image RI and the virtual image VI may be determined by, for example, having a person actually sit in vehicle C view a virtual image surface using a head-mounted display or the like, and evaluating the image from various perspectives, such as whether the real image RI and the virtual image VI can be viewed without strain, and whether the person is likely to be motivated to use them.

[0013] The configuration of the display device 1 shown in Fig. 1 and Fig. 2 will be described in detail. Fig. 3 is a diagram showing a layout when a real image is viewed in the display device 1 according to this embodiment, and Fig. 4 is a diagram showing a layout when a virtual image is viewed in the display device 1 according to this embodiment.

[0014] 3 and 4, the display unit 10 is disposed at a position below the display device 1. This allows the area below the display device 1 to be narrowed and made compact, and allows for efficient layout by taking advantage of the shape inside the instrument panel IP.

[0015] The configuration of the display unit 10 will now be described in more detail. FIG. 5 is a diagram showing the configuration of the display unit 10 in the display device 1 according to this embodiment. As shown in FIG. 5, the display unit 10 includes a light source 111, such as a white LED; a condenser lens 112, which is disposed downstream of the light source 111 and focuses the light beams emitted from the light source 111; a lenticular lens 113 and a diffuser 114, which are disposed downstream of the condenser lens 112 and uniformize the brightness of the light beams focused by the condenser lens 112; a liquid crystal display 115, which is disposed downstream of the liquid crystal display 115 and generates display light L for an image to be viewed by a viewer PS; and a polarizer 116, which transmits only light beams with a specific vibration direction among the display light L with various vibration directions. Here, the display unit 10 is oriented relative to a polarization selection module 20, which will be described later, so as to produce, for example, P-polarized light (first linearly polarized light). These various components constituting the display unit 10 are fixed to and supported by a housing 117.

[0016] The housing 117 is connected to a rod-shaped height adjustment unit 118. This height adjustment unit 118 (advance / retreat drive unit) is twisted and can be rotated in the direction of arrow a by, for example, a stepping motor. A connection unit 119 that is twisted is joined to the housing 117, and the twisted portion of the connection unit 119 and the twisted portion of the height adjustment unit 118 are connected in an engaged state. In other words, the pinion-rack mechanism can displace the position of the display unit 10 in the vertical direction (a normal direction that is approximately perpendicular to the emission direction of display light L of the display unit 10 or the surface direction of the liquid crystal display 115), that is, can displace the display unit 10 so as to advance or retreat relative to the polarization selection module 20, thereby making it possible to adjust the display quality of the display image viewed by the viewer PS.

[0017] 3 and 4, the display unit 10 emits display light L representing a display image to be viewed by a viewer PS from below the display device 1 toward a polarization selective module 20 arranged above it. The polarization selective module 20 is a set of plate-like members that have the property of reflecting light rays of one polarization and transmitting light rays of another polarization orthogonal to the one polarization. Here, the polarization selective module 20 is set to have the property of transmitting P-polarized light rays (first linearly polarized light) and reflecting S-polarized light rays (second linearly polarized light).

[0018] The polarization selective module 20 has a pitch axis in the width direction of the vehicle C, and a rotation axis S along the pitch axis at the center of the polarization selective module 20. The polarization selective module 20 is driven to rotate around the rotation axis S by a rotation drive unit 21 such as a motor so that the angle with respect to the optical path of the display light L is variable.

[0019] 3 and 4, a first mirror 11 that reflects display light L is disposed at a first angular position (a position above the instrument panel IP) along the circumferential direction around the rotation axis S. A second mirror 12 that reflects display light L is disposed at a second angular position different from the first angular position (a position on the far side of the instrument panel IP as seen by the viewer PS or a position approximately perpendicular to the first angular position around the rotation axis S). The first mirror 11 and the second mirror 12 are disposed at positions that reflect the display light L to the polarization selection module 20. A heat sink 50 for heat dissipation is disposed further below the display unit 10 (on the back side of the light source 111). The first mirror 11 and the second mirror 12 may be flat mirrors, but are preferably concave mirrors. In particular, to display a real image RI, the second mirror 12 needs to be a concave mirror.

[0020] The control unit 30 controls the content and display mode of the image displayed by the display unit 10, the rotation angle of the rotation drive unit 21, and the height adjustment of the height adjustment unit 118.

[0021] 3, the position of the optical focus F1 (first optical focus) of the optical member consisting of the first mirror 11, the second mirror 12, and the polarization selective module 20 is set so as to be closer to the opening 17 than the display unit 10 along the optical path of the display light L. Here, it is set between the polarization selective module 20 and the display unit 10. In addition, here, the angle of the polarization selective module 20 is set at an angle (first rotation position) such that the upper part of the polarization selective module 20 (the region above the rotation axis S) is on the viewer side, and one surface of the polarization selective module 20 faces the two mirrors, the first mirror 11 and the second mirror 12. As a result, the display light L emitted from the display unit 10 passes through the polarization selection module 20, is reflected and turned back by the first mirror 11, is reflected by the polarization selection module 20 in a direction approximately perpendicular to the rear side of the viewer PS (the direction in which the second mirror 12 is positioned), is reflected and turned back by the second mirror 12, and passes through the polarization selection module 20 again, allowing the viewer PS to view a real image RI in front of the instrument panel IP.

[0022] 4, the position of the optical focus F2 (second optical focus) of the optical member consisting of the first mirror 11 and the polarization selective module 20 is set to be on the opposite side of the opening 17 from the display unit 10 along the optical path of the display light L. Here, it is set between the display unit 10 and the heat sink 50. The polarization selective module 20 is also set at an angle (second rotation position) such that the lower part of the polarization selective module 20 (the region below the rotation axis S) is on the viewer side, that is, at an angle that is approximately 90 degrees different from the case of FIG. 3, with one surface of the polarization selective module 20 facing the first mirror 11 and the other surface facing the second mirror 12. As a result, the display light L emitted from the display unit 10 passes through the polarization selective module 20, is reflected and folded by the first mirror 11, and is reflected by the polarization selective module 20 toward the viewer PS, that is, in a direction approximately perpendicular to the viewer PS, allowing the viewer PS to view a virtual image VI on the far side of the instrument panel IP.

[0023] In this way, by adopting an optical system in which the display light L passes through the same optical path twice, it is possible to ensure the optical path length and reduce the required volume compared to adopting an optical system in which the display light L passes through the same optical path only once.

[0024] 3, the second mirror 12 is preferably arranged to guide light rays in different directions from the display light L reflected by the second mirror 12, transmitted through the polarization selective module 20, and guided to the viewer PS. This prevents the light directly reflected by the polarization selective module 20 from entering the eyes of the viewer PS and causing them to view the light as an unintended image (stray light). The arrangement of the second mirror 12 is changed within a range that does not significantly deteriorate the imaging performance of the display image of the display light L, and this range may be determined according to required specifications.

[0025] Furthermore, it is desirable to set the tilt of the polarization selection module 20 so that the angle of incidence (angle θ shown in FIG. 3) of the display light L emitted from the display unit 10 is close to Brewster's angle (the angle at which the reflectance of incident P-polarized light is 0 or extremely low). By arranging it in this way, stray light can be prevented as much as possible.

[0026] Next, a detailed description will be given of the process by which the real image RI and the virtual image VI are formed in each of the configurations of Figures 3 and 4. Figure 6 is a diagram showing the structure of the polarization selection module 20 in the display device 1 according to this embodiment, Figure 7 is a diagram explaining the transition of the polarization state of the display light L when the real image RI is viewed in the display device 1 according to this embodiment, and Figure 8 is a diagram explaining the transition of the polarization state of the display light L when the virtual image VI is viewed in the display device 1 according to this embodiment.

[0027] The polarization selective module 20 shown in FIG. 6 is formed by laminating a base material 201, a polarization selective plate 203, and a 1 / 4λ plate 202 in this order. The base material 201 is a base for attaching and supporting various components, and is made of glass such as optical glass or acrylic glass. Note that tempered glass may also be used in consideration of the increased size of the display device 1 and the effects of vibrations of the vehicle C. Glass generally does not have a 100% reflectivity, and some light rays are reflected. To address this situation, an AR (Anti-Reflection) film may be attached to the bottom of the base material 201 (the side where the display unit 10 is located), or a coating may be applied to allow more light rays to pass through.

[0028] The quarter-lambda plate 202 is a film-like member that has the function of delaying the phase of polarized light by π / 4. This function makes it possible to convert linearly polarized light into circularly polarized light and circularly polarized light into linearly polarized light. However, there are two types of circularly polarized light: left-handed circularly polarized light and right-handed circularly polarized light, and the type of circularly polarized light that linearly polarized light becomes is determined by how the quarter-lambda plate 202 is positioned. In Figures 7 and 8, which will be described later, it is assumed that the quarter-lambda plate 202 is positioned to convert P-polarized light (linearly polarized light) into left-handed circularly polarized light (first circularly polarized light) and left-handed circularly polarized light (first circularly polarized light) into P-polarized light (linearly polarized light).

[0029] The polarization selection plate 203 is a member that has the property of reflecting a specific circularly polarized light (for example, right-handed circularly polarized light (second circularly polarized light)) and transmitting circularly polarized light of the opposite direction (for example, left-handed circularly polarized light (first circularly polarized light)), and is known to be, for example, a liquid crystal polymer layer. A liquid crystal polymer layer has the property of highly reflecting right-handed circularly polarized light and highly transmitting left-handed circularly polarized light. Specifically, it is known that the reflectance of right-handed circularly polarized light is approximately 70%, and the transmittance of left-handed circularly polarized light is approximately 90%. Furthermore, it is known that the material has the property of reflecting right-handed circularly polarized light again as right-handed circularly polarized light, a property not seen in ordinary mirrors.

[0030] Based on the function of the polarization selection module 20 shown in FIG. 6, the transition of the polarization state until the display images in FIGS. 7 and 8 are formed will be described.

[0031] In FIG. 7, the polarization selection module 20 is disposed so that the quarter-lambda plate 202 is located closer to the display unit 10 (lower in the drawing) than the polarization selection plate 203. First, P-polarized display light L is emitted from the display unit 10 and enters the polarization selection module 20. At this time, the polarization of the display light L is converted from P-polarized to left-handed circularly polarized light by passing through the quarter-lambda plate 202, and then passes through the polarization selection plate 203 and proceeds toward the first mirror 11. The left-handed circularly polarized display light L is converted to right-handed circularly polarized light by reflection on the first mirror 11. Note that the reversal of the direction of circular polarization on a mirror surface is a well-known physical phenomenon. Next, the right-handed circularly polarized display light L is reflected by the polarization selection plate 203 and proceeds toward the second mirror 12. At this time, due to the characteristics of the polarization selection plate 203 described above, the polarization of the reflected display light L remains right-handed circularly polarized. Then, when the right-handed circularly polarized display light L is reflected by the second mirror 12, it becomes left-handed circularly polarized light and passes through the polarization selection plate 203 due to the characteristics of the polarization selection plate 203 described above. The left-handed circularly polarized display light L that passes through the polarization selection plate 203 is converted into P-polarized light by the 1 / 4λ plate 202 and emitted outside the display device 1, thereby enabling the viewer PS to view the real image RI, as shown in Figures 1 and 3.

[0032] 8, similarly to the case of FIG. 7, the polarization selection module 20 is disposed so that the ¼λ plate 202 is located closer to the display unit 10 (lower in the drawing) than the polarization selection plate 203. First, P-polarized display light L is emitted from the display unit 10 and enters the polarization selection module 20. At this time, the polarization of the display light L is converted from P-polarized to left-handed circularly polarized light by passing through the ¼λ plate 202, and then passes through the polarization selection plate 203 and proceeds toward the first mirror 11. The left-handed circularly polarized display light L is converted to right-handed circularly polarized light by reflection on the first mirror 11. Next, due to the characteristics of the polarization selection plate 203 described above, the right-handed circularly polarized display light L is reflected by the polarization selection plate 203 and emitted directly to the outside of the display device 1. As a result, the viewer PS is able to view the virtual image VI, as shown in FIGS. 2 and 4.

[0033] The internal layout of the display device 1 may be such that the display unit 10 is disposed at the top and the first mirror 11 is disposed at the bottom. In this case, the arrangement is adjusted so that the transition of the polarization state of the display light L follows the same principle as in the case described above. For example, in the above description, when the real image RI is viewed, the polarization selection module 20 is rotated so as to tilt to the right in the drawing (toward the second mirror 12), and when the virtual image VI is viewed, the polarization selection module 20 is rotated so as to tilt to the left in the drawing (toward the first mirror 11). However, when the top and bottom are reversed, the arrangement is such that the tilt is reversed left and right.

[0034] As described above, the display device 1 according to this embodiment includes a display unit 10 that includes a light source 111, emits light from the light source 111 as a first linearly polarized light (for example, P-polarized light), and displays a display image; a polarization selection module 20 that reflects a second linearly polarized light (for example, S-polarized light) orthogonal to the first linearly polarized light and transmits the first linearly polarized light; a rotation drive unit 21 that rotates the polarization selection module 20 around a rotation axis S so that the angle with respect to the optical path of the display light L is variable; a control unit 30 that controls at least the rotation drive unit 21; and a first mirror 11 and a second mirror 12 that are arranged at positions to reflect the display light L to the polarization selection module 20, wherein the first mirror 11 is provided at a first angular position (for example, a position above an instrument panel IP) along the circumferential direction around the rotation axis S, and the second mirror 12 is provided at a second angular position different from the first angular position. The control unit 30 controls the rotation drive unit 21 to rotate the polarization selection module 20 to a first rotation position for displaying a real image RI, where, when a real image RI is to be viewed, the display light L emitted from the display unit 10 is transmitted, the display light L reflected by the first mirror 11 is incident, and then the reflected and emitted display light L is directed toward the second mirror 12, and the display light L reflected by the second mirror 12 is transmitted and directed toward the opening 17. When a virtual image VI is to be viewed, the control unit 30 controls the rotation drive unit 21 to rotate the polarization selection module 20 to a second rotation position for displaying a virtual image VI, where the display light L emitted from the display unit 10 is transmitted, the display light L reflected by the first mirror 11 is incident, and then the reflected and emitted display light L is directed toward the opening 17 without passing through the second mirror 12.

[0035] As a result, when the viewer PS is to view the real image RI, the polarization selection module 20 is rotated to the first rotation position, and a relatively long optical path length is achieved in the path from the display unit 10, the polarization selection module 20, the first mirror 11, the polarization selection module 20, the second mirror 12, the polarization selection module 20, and the opening 17, so that the real image RI can be viewed in front of the instrument panel IP as seen by the viewer PS.

[0036] When the viewer PS is to view the virtual image VI, the polarization selection module 20 is rotated to the second rotation position, and a relatively short optical path length is achieved in the path from the display unit 10, the polarization selection module 20, the first mirror 11, the polarization selection module 20, and the opening 17, so that the virtual image VI can be viewed at the back of the instrument panel IP as seen by the viewer PS.

[0037] In this case, by forming an optical path that passes through the same location (polarization selection module 20) twice when the real image RI is viewed, it is possible to increase the optical path length without increasing the size of the entire display device 1. As a result, it is possible to improve the ease of installation in an instrument panel IP, which has space constraints.

[0038] The polarization selection module 20 also includes a 1 / 4λ plate 202 that can convert linearly polarized light into a first circularly polarized light (e.g., left-handed circularly polarized light) and convert the first circularly polarized light into linearly polarized light, and a polarization selection plate 203 that transmits the first circularly polarized light and reflects a second circularly polarized light (e.g., right-handed circularly polarized light) that is opposite to the first circularly polarized light.

[0039] As a result, when the viewer PS is to view the real image RI, the first linearly polarized light (e.g., P-polarized light) emitted from the display unit 10 is converted into first circularly polarized light (e.g., left-handed circularly polarized light) by the ¼λ plate 202 as it passes through the polarization selection module 20 in the first rotation position, and then reflected by the first mirror 11 to become second circularly polarized light (e.g., right-handed circularly polarized light) and return. The returned second circularly polarized light is further reflected by the polarization selection plate 203 of the polarization selection module 20 and emitted to the second mirror 12. The emitted second circularly polarized light is reflected by the second mirror 12 to become first circularly polarized light and return, passes through the polarization selection plate 203 of the polarization selection module 20, and is converted into the first linearly polarized light by the ¼λ plate 202, and then heads toward the opening 17. This achieves a relatively long optical path length, allowing the viewer PS to view the real image RI on the closer side than the instrument panel IP as viewed from the viewer PS.

[0040] When the viewer PS is to view the virtual image VI, the first polarized light emitted from the display unit 10 is converted into first circularly polarized light (for example, left-handed circularly polarized light) by the ¼λ plate 202 as it passes through the polarization selection module 20 in the second rotation position, and is then reflected by the first mirror 11 to become second circularly polarized light (for example, right-handed circularly polarized light) and return. The returned second circularly polarized light is reflected by the polarization selection plate 203 and travels toward the opening 17. This achieves a relatively short optical path length, allowing the viewer PS to view the virtual image VI on the far side of the instrument panel IP.

[0041] Furthermore, in both the first rotation position and the second rotation position of the polarization selection module 20, the 1 / 4λ plate 202 is positioned closer to the display unit 10 than the polarization selection plate 203, and this arrangement ensures that the path behavior of the display light L as described above can be achieved.

[0042] Furthermore, when the polarization selective module 20 is in the first rotation position, the optical focus F1 of the imaging optical system including the first mirror 11, the second mirror 12, and the polarization selective module 20 is located on the opening 17 side of the display unit 10 along the optical path of the display light L, and when the polarization selective module 20 is in the second rotation position, the optical focus F2 of the imaging optical system including the first mirror 11 and the polarization selective module 20 is located on the opposite side of the opening 17 from the display unit 10 along the optical path of the display light L.Therefore, by simply switching the polarization selective module 20 to the first rotation position or the second rotation position, the real image RI and the virtual image VI can be smoothly switched and viewed.

[0043] Furthermore, since the display unit 10 further includes a height adjustment unit 118 that moves the display unit 10 forward and backward relative to the polarization selection module 20, the display can be made clearer and the display quality can be improved by appropriately adjusting the distance between the display unit 10 and the polarization selection module 20 when switching between real image RI display and virtual image VI display.

[0044] Furthermore, the above-described configuration increases the transmittance and reflectance compared to when a half mirror is used, thereby increasing the luminance efficiency and reducing the amount of light emitted from the display unit 10, i.e., reducing power consumption. In addition, the high transmittance and reflectance also reduce the luminance of unintended light rays, reducing stray light.

[0045] Furthermore, in the display device 1 according to this embodiment, the display device 1 is mounted in a glove compartment on the passenger seat side, and a viewer PS sitting in the passenger seat can view the real image RI and the virtual image VI. For example, on a screen for selecting which content to view, a real image RI that appears to float in front of the glove compartment can be displayed, and when playback of the content actually begins, a virtual image VI that appears to sink into the glove compartment can be displayed. The content played here can be, for example, entertainment content unrelated to driving (games or movies).

[0046] (Second embodiment of the present invention) A display device 1 according to this embodiment will be described with reference to the drawings. In the display device 1 according to the first embodiment, the ¼λ plate 202 is provided in the polarization selection module 20, but in the display device 1 according to this embodiment, the ¼λ plate 202 is provided in the first mirror 11 and the second mirror 12. Note that descriptions of this embodiment that overlap with those of the first embodiment will be omitted.

[0047] Figure 9 is a diagram showing the structure of the polarization selection module 20 and the first and second mirrors 11 and 12 in the display device 1 of this embodiment, Figure 10 is a diagram explaining the transition of the polarization state of the display light L when a real image RI is viewed in the display device 1 of this embodiment, and Figure 11 is a diagram explaining the transition of the polarization state of the display light L when a virtual image VI is viewed in the display device 1 of this embodiment.

[0048] 9, the polarization selection module 20 has only a polarization selection plate 203 attached to a base material 201. In addition, a first 1 / 4λ plate 202a and a second 1 / 4λ plate 202b are attached to the surfaces of the first mirror 11 and the second mirror 12, respectively.

[0049] 9 is a member that has the property of transmitting a specific linearly polarized light and effectively reflecting linearly polarized light that is orthogonal to that light, and a known example of such a member is a cold mirror film (CMF). A CMF has the property of transmitting, for example, P-polarized light and reflecting S-polarized light, and a specific CMF with a transmittance of P-polarized light and a reflectance of S-polarized light of about 80% is known.

[0050] 9, the first mirror 11 and the first 1 / 4λ plate 202a are arranged so that the P-polarized display light L is reflected by the first mirror 11 and enters the polarization selective module 20 again as S-polarized light. The second mirror 12 and the second 1 / 4λ plate 202b are arranged so that the S-polarized display light L is reflected by the second mirror 12 and enters the polarization selective module 20 again as P-polarized light.

[0051] In the configuration shown in FIG. 9, the transition of the polarization state until the display images shown in FIGS. 10 and 11 are formed will be described.

[0052] 10 , first, P-polarized display light L is emitted from the display unit 10 and enters the polarization selection module 20. At this time, as described above, the polarization selection plate 203 transmits P-polarized light, so the display light L goes directly to the first mirror 11. Thereafter, the first ¼λ plate 202a converts the P-polarized light into left-handed circularly polarized light, reflects it off the first mirror 11 to become right-handed circularly polarized light, and then converts it back into S-polarized linearly polarized light by the first ¼λ plate 202a before it enters the polarization selection module 20. The S-polarized linearly polarized light is then reflected by the polarization selection plate 203 of the polarization selection module 20 and goes toward the second mirror 12. Subsequently, the S-polarized light is converted into right-handed circularly polarized light by the second ¼λ plate 202b, reflects it off the second mirror 12 to become left-handed circularly polarized light, and then converts it back into P-polarized linearly polarized light by the second ¼λ plate 202b before it enters the polarization selection module 20. Then, the display light L is transmitted through the polarization selection module 20 and emitted to the outside of the display device 1, thereby enabling the viewer PS to view the real image RI.

[0053] 11, first, P-polarized display light L is emitted from the display unit 10 and enters the polarization selection module 20, and the display light L proceeds directly to the first mirror 11. Thereafter, the first ¼λ plate 202a converts the P-polarized light into left-handed circularly polarized light, reflects off the first mirror 11 to become right-handed circularly polarized light, and then converts it back into S-polarized linearly polarized light by the first ¼λ plate 202a and enters the polarization selection module 20. Then, due to the characteristics of the polarization selection plate 203 described above, the S-polarized display light L is reflected by the polarization selection plate 203 and is directly emitted outside the display device 1. This allows the viewer PS to view the virtual image VI. In Figures 10 and 11, for ease of explanation, the first 1 / 4λ plate 202a and the second 1 / 4λ plate 202b are shown on a plane spaced apart from the first mirror 11 and the second mirror 12, respectively, but in reality, they are stacked adjacent to the first mirror 11 and the second mirror 12, respectively, as shown in Figure 9.

[0054] As described above, the display device 1 according to this embodiment has a first 1 / 4λ plate 202a and a second 1 / 4λ plate 202b on the polarization selective module 20 side (surface of the first mirror 11) of the first mirror 11 and on the polarization selective module 20 side (surface of the second mirror 12) of the second mirror 12, respectively, which convert first linearly polarized light (e.g., P-polarized light) into first circularly polarized light (e.g., left-handed circularly polarized light) and convert the first circularly polarized light into the first linearly polarized light, convert second linearly polarized light (e.g., S-polarized light) into second circularly polarized light (e.g., right-handed circularly polarized light) and convert the second circularly polarized light into the second linearly polarized light, and the polarization selective module 20 has a polarization selective plate 203 which transmits the first linearly polarized light and reflects the second linearly polarized light that is orthogonal to the first linearly polarized light.

[0055] As a result, when the viewer PS is made to view the real image RI, the first linearly polarized light (for example, P-polarized light) emitted from the display unit 10 passes through the polarization selection plate 203 of the polarization selection module 20 which is in the first rotation position, and is then converted into first circularly polarized light (for example, left-handed circularly polarized light) by the first ¼λ plate 202a on the polarization selection module 20 side (front side) of the first mirror 11, and is then reflected by the first mirror 11 to become second circularly polarized light (for example, right-handed circularly polarized light) and return. The returned second circularly polarized light is then further converted into second linearly polarized light (for example, S-polarized light) by the first ¼λ plate 202a on the polarization selection module 20 side, and is then reflected by the polarization selection plate 203 of the polarization selection module 20 and is emitted to the second mirror 12. The emitted second linearly polarized light is converted into second circularly polarized light by the second 1 / 4λ plate 202b on the polarization selective module 20 side (front side) of the second mirror 12, and then reflected by the second mirror 12 to become first circularly polarized light and return. The returned first circularly polarized light is further converted into first linearly polarized light by the second 1 / 4λ plate 202b on the polarization selective module 20 side, and then passes through the polarization selective plate 203 and heads toward the opening 17. This achieves a relatively long optical path length, allowing the viewer PS to view the real image RI on the closer side than the instrument panel IP.

[0056] Furthermore, when the viewer PS is to view a virtual image VI, the first linearly polarized light (e.g., P-polarized light) emitted from the display unit 10 passes through the polarization selection plate 203 of the polarization selection module 20 in the second rotation position, is converted into first circularly polarized light (e.g., left-handed circularly polarized light) by the first ¼λ plate 202a on the polarization selection module 20 side (front side) of the first mirror 11, is then reflected by the first mirror 11, and is returned as second circularly polarized light (e.g., right-handed circularly polarized light). The returned second circularly polarized light is further converted into second linearly polarized light (e.g., S-polarized light) by the first ¼λ plate 202a on the polarization selection module 20 side, is then reflected by the polarization selection plate 203 of the polarization selection module 20, and is directed toward the opening 17. This achieves a relatively short optical path length, allowing the viewer PS to view the virtual image VI on the far side of the instrument panel IP.

[0057] Furthermore, with the above-described configuration, it is possible to reduce the deviation in color after passing through the optical system, compared to the display device 1 according to the first embodiment.

[0058] Furthermore, since the polarization of the display light L that is finally emitted becomes linearly polarized light, it becomes easier to cut off unintended light rays using a polarizing plate or the like.

[0059] Furthermore, the above-described configuration increases the transmittance and reflectance compared to when a half mirror is used, thereby increasing the luminance efficiency and reducing the amount of light emitted from the display unit 10, i.e., reducing power consumption. In addition, the high transmittance and reflectance also reduce the luminance of unintended light rays, reducing stray light.

[0060] (Other embodiments of the present invention) The feasibility of displaying a real image RI and a virtual image VI in the display device 1 according to the first embodiment will be described using specific numerical values. FIG. 12 shows a diagram in which a system capable of displaying a real image RI is rearranged into a coaxial system. The liquid crystal display 115 is placed on the left side of this mirror system. The positional relationship between the liquid crystal display 115, the first mirror 11, and the second mirror 12 that allows the real image RI to be displayed will be described. In FIG. 12, light traveling from the left (the liquid crystal display 115 side) to the right is defined as the positive direction. The radius of curvature of the boundary surface is defined as a positive radius of curvature when the convex surface faces left, and a negative radius of curvature when the convex surface faces right. Furthermore, the height direction is defined as positive in the upward direction (the side indicated by the sign) and negative in the downward direction.

[0061] 12, the polarization selection module 20 is in the first rotation position, and for example, the radius of curvature of the first mirror 11 is set to -700 mm, the radius of curvature of the second mirror 12 is set to 300 mm, and the second mirror 12 is located at a position -220 mm from the first mirror 11. The liquid crystal display 115 is placed at a position 250 mm away from the first mirror 11.

[0062] In this optical system arrangement, the liquid crystal display 115 is located to the left of the optical focus F1 of the optical system, and it can be seen that the light rays emitted from the liquid crystal display 115 form a real image RI.

[0063] 13 shows the optical system when the polarization selection module 20 is in the second rotation position. At this time, it can be seen that the position of the optical focus F2 is to the right of the position of the liquid crystal display 115. From this, it can be seen that the light beam emitted from the liquid crystal display 115 forms a virtual image VI.

[0064] The above discussion is based solely on the paraxial theory. However, as the size of the image to be displayed increases, the angle between the light ray and the optical axis also increases. This means that the discussion of imaging performance cannot be fully explained by paraxial theory alone, and various aberrations, including Seidel's five aberrations, occur within this range. In such cases, it is desirable to correct aberrations as much as possible by giving the first mirror 11 and the second mirror 12 shapes that are more complex than spherical. For example, aspherical or free-form surfaces may also be used.

[0065] Alternatively, as shown in FIG. 14, for example, a lens having a focusing function may be inserted between the display unit 10 and the polarization selective module 20, or along the optical path of the display light L, between the polarization selective module 20 and the viewer PS. FIG. 14 is a diagram showing an example of a configuration in which a lens is inserted in the optical path of the display light L in the display device 1 according to this embodiment. By inserting lenses 171, 172 as shown in FIG. 14, it is possible to enlarge the real image RI and the virtual image VI that can be displayed by the first mirror 11 and the second mirror 12. In other words, this makes it possible to reduce the sizes of the first mirror 11 and the second mirror 12 required to display an image of a specific size.

[0066] Inserting lenses 171 and 172 as described above may result in chromatic aberration. This is a phenomenon that occurs because the refractive index of the material used for lenses 171 and 172 depends on the wavelength of the light. When this phenomenon occurs, the image contours of the image may appear rainbow-colored because the image is focused at different positions for each wavelength, which can impair display quality. To address this issue, the lenses may be given achromatic properties. It is known that achromatization requires the use of at least two glasses or resins with different Abbe numbers v, one with positive power (the ability to focus light) and one with negative power (the ability to diverge light).

[0067] Here, the Abbe number is an index of how easily the refractive index changes depending on the wavelength, and the refractive index at the d line (587.56 nm: equivalent to orange light) is expressed as n d, the refractive index at C line (665.27 nm: equivalent to red light) is n C , the refractive index at F line (486.13 nm: equivalent to blue light) is n F Then, the Abbe number v is

[0068] (Number 1) TIFF2025128593000002.tif3368

[0069] Also, 1 / v is called the dispersion of the material, and the larger this value is, the greater the influence of the change in refractive index for each wavelength, and the smaller this value is, the smaller the influence of the refractive index for each wavelength is.

[0070] To reduce chromatic aberration, materials with different Abbe numbers are used. A well-known combination of lenses that achieves this is called a doublet lens. Figure 15 shows the structure of a doublet lens. A doublet lens is made by creating lenses from materials with different refractive indices and then tightly bonding them together. For example, as shown in Figure 15, the first lens DL1 on the left is made of the first material and has a convex lens-like shape. The second lens DL2 on the right is made of the second material and has a concave surface on the left with the same radius of curvature as the right side of the first lens DL1, and a flat surface on the right side. The doublet lens is completed by tightly bonding the first lens DL1 and the second lens DL2 together. In this case, the first and second materials are arranged so that the first material is located in the front stage (incoming side) and the second material is located in the back stage (exiting side). If the Abbe number of the first material is v1 and the Abbe number of the second material is v2, then chromatic aberration can be effectively eliminated. In addition, since the lens shown in Figure 15 has positive power, light rays passing through this lens are refracted in the direction of convergence, which can contribute to the miniaturization of the first mirror 11 and the second mirror 12.

[0071] By arranging lenses having such properties as lenses 171 and 172 as shown in FIG. 14, an optical system in which chromatic aberration is effectively suppressed can be constructed.

[0072] (Appendix 1-1) A display device provided in an instrument panel of a vehicle, the display device emitting display light from an emission port to allow a user to visually recognize a real image of a display image represented by the display light, a display unit including a light source, emitting light from the light source as a first linearly polarized light and displaying the display image; a polarization selection module that reflects a second linearly polarized light that is orthogonal to the first linearly polarized light and transmits the first linearly polarized light; a first mirror and a second mirror disposed at positions to reflect the display light to the polarization selection module; The polarization selection module is arranged so that the display light emitted from the display unit is transmitted, and the display light reflected by the first mirror is incident, and then the direction of the reflected and emitted display light is toward the second mirror, and the direction of the display light that has been transmitted after being reflected by the second mirror is toward the exit.

[0073] (Appendix 2) The polarization selection module includes a ¼λ plate capable of converting linearly polarized light into a first circularly polarized light and converting the first circularly polarized light into the linearly polarized light; a polarization selective plate that transmits the first circularly polarized light and reflects a second circularly polarized light having an opposite direction to the first circularly polarized light; The present invention is characterized by comprising:

[0074] (Appendix 3-1) The polarization selection module is characterized in that the 1 / 4λ plate is located closer to the display unit than the polarization selection plate.

[0075] (Appendix 4) The polarization selection module further includes a ¼λ plate that converts the first linearly polarized light into a first circularly polarized light and converts the first circularly polarized light into the first linearly polarized light, converts the second linearly polarized light into a second circularly polarized light, and converts the second circularly polarized light into the second linearly polarized light, and the first mirror and the second mirror are disposed on the polarization selection module side, The polarization selection module comprises: The optical element is characterized by comprising a polarization selection plate that transmits the first linearly polarized light and reflects the second linearly polarized light.

[0076] (Appendix 5) The first mirror and the second mirror are each a concave mirror.

[0077] (Appendix 6-1) The first optical focal point of an imaging optical system including the first mirror, the second mirror, and the polarization selection module is located closer to the exit port than the display unit along the optical path.

[0078] (Appendix 7) The present invention is also characterized in that a plurality of lens members are provided between the polarization selection module and the exit port side.

[0079] (Appendix 8) The lens member on the exit side is colored.

[0080] (Appendix 1-2) Further, a display device for visually recognizing a virtual image and the real image, a rotation drive unit that rotates the polarization selection module around a rotation axis so that the angle with respect to the optical path is variable; a control unit that controls the rotation drive unit; and the first mirror is provided at a first angular position along a circumferential direction around the rotation axis, and the second mirror is provided at a second angular position different from the first angular position; The control unit controls the rotation drive unit, When the real image is to be viewed, the polarization selection module is rotated to a first rotation position for displaying a real image; When the virtual image is to be viewed, the polarization selection module is rotated to a second rotation position for displaying a virtual image, in which the display light emitted from the display unit is transmitted, the display light is reflected by the first mirror, and then reflected and emitted, so that the direction of the display light is directed toward the exit without passing through the second mirror.

[0081] (Appendix 3-2) The polarization selection module further comprises: In both the first rotation position and the second rotation position, the ¼λ plate is located closer to the display unit than the polarization selection plate.

[0082] (Appendix 6-2) and when the polarization selective module is at the first rotation position, a first optical focal point of an imaging optical system including the first mirror, the second mirror, and the polarization selective module is located closer to the exit port than the display unit along the optical path. When the polarization selective module is in the second rotational position, a second optical focus of the imaging optical system including the first mirror and the polarization selective module is located on the opposite side of the output port along the optical path from the display unit.

[0083] (Appendix 9) The display device further comprises a forward / backward driving unit that moves the display unit forward / backward relative to the polarization selection module. [Explanation of symbols]

[0084] C vehicle DL1 First Lens DL2 Second Lens F1,F2 optical focus IP instrument panel L display light Lr rays PS Viewer RI real image S rotation axis VI Virtual Image 1 Display device 10 Display 11 1st mirror 12 Second mirror 17 Opening (injection port) 20 Polarization Selection Module 21 Rotation drive unit 30 Control Unit 50 Heatsink 111 Light source 112 Condenser Lens 113 Lenticular Lens 114 Diffuser 115 LCD display 116 Polarized Plate 117 Housing 118 Height adjustment unit 119 Connection 171,172 lenses 201 Base material 202 1 / 4λ plate 202a First 1 / 4λ plate 202b Second 1 / 4λ plate 203 Polarization Selective Plate

Claims

1. A display device provided in an instrument panel of a vehicle, emitting display light from an emission port to allow a virtual image and a real image of a display image represented by the display light to be visually recognized, a display unit including a light source, emitting light from the light source as a first linearly polarized light and displaying the display image; a polarization selection module that reflects a second linearly polarized light that is orthogonal to the first linearly polarized light and transmits the first linearly polarized light; a rotation drive unit that rotates the polarization selection module around a rotation axis so that the angle with respect to the optical path is variable; a control unit that controls the rotation drive unit; a first mirror and a second mirror disposed at positions to reflect the display light to the polarization selective module; the first mirror is provided at a first angular position along a circumferential direction around the rotation axis, and the second mirror is provided at a second angular position different from the first angular position, The control unit controls the rotation drive unit, When the real image is to be viewed, the polarization selection module is rotated to a first rotation position for real image display, where the display light emitted from the display unit is transmitted, the display light reflected by the first mirror is incident, and then the direction of the reflected and emitted display light is directed toward the second mirror, and the direction of the display light after the transmission of the display light reflected by the second mirror is directed toward the exit port; A display device characterized in that, when the virtual image is viewed, the polarization selection module is rotated to a second rotation position for virtual image display, in which the display light emitted from the display unit is transmitted, and the display light reflected by the first mirror is incident and then reflected and emitted, so that the direction of the display light is toward the exit without passing through the second mirror.

2. The polarization selection module comprises: a ¼λ plate capable of converting linearly polarized light into a first circularly polarized light and converting the first circularly polarized light into the linearly polarized light; a polarization selective plate that transmits the first circularly polarized light and reflects a second circularly polarized light having an opposite direction to the first circularly polarized light; 2. The display device according to claim 1, further comprising:

3. The polarization selection module comprises:

3. The display device according to claim 2, wherein the quarter-lambda plate is positioned closer to the display unit than the polarization selection plate is at both the first rotation position and the second rotation position.

4. a ¼λ plate on the polarization selection module side of the first mirror and the second mirror, which converts the first linearly polarized light into a first circularly polarized light and converts the first circularly polarized light into the first linearly polarized light, converts the second linearly polarized light into a second circularly polarized light and converts the second circularly polarized light into the second linearly polarized light, The polarization selection module comprises:

2. The display device according to claim 1, further comprising a polarization selection plate that transmits the first linearly polarized light and reflects the second linearly polarized light.

5. 5. The display device according to claim 1, wherein the first mirror and the second mirror are concave mirrors.

6. a first optical focal point of an imaging optical system including the first mirror, the second mirror, and the polarization selective module when the polarization selective module is at the first rotation position is located closer to the exit port than the display unit along the optical path; 5. A display device according to claim 1, wherein when the polarization selective module is in the second rotation position, a second optical focus of an imaging optical system including the first mirror and the polarization selective module is located on the opposite side of the light path from the exit port relative to the display unit.

7. 5. The display device according to claim 1, further comprising a forward / backward driving unit that moves the display unit forward and backward relative to the polarization selection module.

Images