Display device

Abstract

A display device is provided with: a display unit (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 the S-polarized light and transmits the P-polarized light; and a first mirror (11) and a second mirror (12) that are disposed at positions at which the display light (L) is reflected toward the polarization selection module, the polarization selection module being disposed such that 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 display light emitted by reflection is directed toward the second mirror. The direction of the display light reflected by the second mirror is directed toward the exit opening (17) after the display light is transmitted. According to the display device of the present invention, by adopting a structure for rotating the polarization selection module, the mounting performance relative to a device in an instrument panel can be good, and a display image can be formed.

Description

Technical Field

[0001] The present invention relates to a display device that provides a desired display to a visual observer. Background Art

[0002] In the prior art, for example, a display device described in Patent Document 1 is known. This display device comprises an optical system installed in a vehicle and forming a real image in front of a visual observer, and an optical system forming a virtual image. By switching between these systems, the visual observer can view the display at different display distances. Specifically, the virtual image is visually recognized as extending outside the vehicle, while the real image is visually recognized as being located inside the vehicle.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2011-70074 Summary of the Invention

[0006] Problems to be solved by the invention

[0007] However, if, for example, it is desired to visually confirm a displayed image without using the front window (windshield), as disclosed in Patent Document 1, the optical system must be implemented within the instrument panel. This requires the optical path length to be determined when displaying a real or virtual image. This results in an increase in the overall size of the device, which can compromise its fit within the instrument panel.

[0008] Therefore, the present invention has been made in view of the above-mentioned problems, and an object thereof is to provide a display device that can form a display image while having good mountability in a device inside an instrument panel by adopting a structure in which a polarization selection module is rotated.

[0009] Means for solving problems

[0010] The present invention is a display device 1, which is arranged in an instrument panel IP of a vehicle C and visually recognizes a real image RI of a display image represented by the display light L by emitting display light L from an emission port 17. The display device includes: a display unit 10 having a light source 111, which emits light from the light source 111 as first linearly polarized light and displays the display image; a polarization selection module 20 that reflects second linearly polarized light orthogonal to the first linearly polarized light and transmits the first linearly polarized light; and a first reflector 11 and a second reflector 12 that are arranged at a position to reflect the display light L toward the polarization selection module 20, wherein the polarization selection module 20 is configured to transmit the display light L emitted from the display unit 10, direct the display light L reflected by the first reflector 11, reflected, and emitted toward the second reflector 12, and direct the display light L reflected by the second reflector 12, after being transmitted, toward the emission port 17.

[0011] Effects of the Invention

[0012] According to the present invention, it is possible to form a display image without using a windshield while improving the installability in the instrument panel. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 1 is a diagram showing a state in which a viewer visually recognizes a real image in the display device according to the first embodiment of the present invention.

[0014] Figure 2 1 is a diagram showing a state in which a viewer visually recognizes a virtual image in the display device according to the first embodiment of the present invention.

[0015] Figure 3 It is a diagram showing a layout when a real image is visually recognized in the display device according to the first embodiment of the present invention.

[0016] Figure 4 It 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.

[0017] Figure 5 It is a diagram showing the configuration of a display unit in a display device according to the first embodiment of the present invention.

[0018] Figure 6 It is a diagram showing the configuration of a polarization selection module in a display device according to the first embodiment of the present invention.

[0019] Figure 7These are diagrams for explaining transitions in the polarization state of display light when a real image is visually recognized in the display device according to the first embodiment of the present invention.

[0020] Figure 8 These are diagrams for explaining transitions in the polarization state of display light when a virtual image is visually recognized in the display device according to the first embodiment of the present invention.

[0021] Figure 9 It is a diagram showing the configuration of a polarization selection module, a first reflecting mirror, and a second reflecting mirror in a display device according to a second embodiment of the present invention.

[0022] Figure 10 These are diagrams for explaining transitions in the polarization state of display light when a real image is visually recognized in the display device according to the second embodiment of the present invention.

[0023] Figure 11 These are diagrams for explaining transitions in the polarization state of display light when a virtual image is visually recognized in the display device according to the second embodiment of the present invention.

[0024] Figure 12 This is a diagram showing a display device according to another embodiment of the present invention in which a system capable of displaying a real image is replaced with a coaxial system.

[0025] Figure 13 This is a diagram showing a display device according to another embodiment of the present invention in which a system capable of displaying a virtual image is replaced with a coaxial system.

[0026] Figure 14 This is a diagram showing an example of a configuration in which a lens is inserted into the optical path of display light in a display device according to another embodiment of the present invention.

[0027] Figure 15 It is a diagram showing the structure of a doublet lens.

[0028] Figure 16 It is a diagram showing the structure of multiple lenses.

[0029] Explanation of symbols

[0030] C: Vehicle;

[0031] DL1: first lens;

[0032] DL2: second lens;

[0033] DL3: third lens;

[0034] DL4: fourth lens;

[0035] DL5: fifth lens;

[0036] F1, F2: optical focus;

[0037] IP: Dashboard;

[0038] L: display light;

[0039] Lr: light;

[0040] PS: visual observer;

[0041] RI: real image;

[0042] S: rotation axis;

[0043] VI: virtual image;

[0044] 1: Display device;

[0045] 10: Display unit;

[0046] 11: first reflector;

[0047] 12: second reflector;

[0048] 17: opening (injection port);

[0049] 20: polarization selection module;

[0050] 21: Rotation drive unit;

[0051] 30: Control Department;

[0052] 50: Radiator;

[0053] 111: light source;

[0054] 112: focusing lens;

[0055] 113: Biconvex lens;

[0056] 114: diffuser plate;

[0057] 115: LCD display;

[0058] 116: polarizing plate;

[0059] 117: shell;

[0060] 118: height adjustment unit;

[0061] 119: connecting part;

[0062] 171, 172: lens;

[0063] 201: substrate;

[0064] 202: 1 / 4λ plate;

[0065] 202a: first 1 / 4λ plate;

[0066] 202b: second 1 / 4λ plate;

[0067] 203: Polarization selection plate. DETAILED DESCRIPTION

[0068] (First embodiment of the present invention)

[0069] A display device according to this embodiment will be described with reference to the drawings. Figure 1 1 is a diagram showing a state in which a real image is visually recognized by a visual observer in the display device according to the present embodiment. Figure 2 : is a diagram showing a state in which a virtual image is visually recognized by a visual observer in the display device according to this embodiment. Figure 1 and Figure 2 In the present invention, a display device 1 is mounted in an instrument panel IP (hereinafter referred to as instrument panel IP) provided at the front of the interior of a vehicle C. The display device 1 includes a display unit 10 that displays a display image visually recognized by a viewer PS; a polarization selection module 20 that transmits a first linearly polarized light from the display unit 10 and reflects a second linearly polarized light orthogonal to the first linearly polarized light, rotating about a rotation axis S so as to change the angle relative to the optical path; and a control unit 30 that controls the display mode of the display unit 10 and the rotation angle of the polarization selection module 20. Display light L emitted from the display unit 10 is emitted from an opening (emission port) 17 of the instrument panel IP via the polarization selection module 20 and reflective mirrors (first reflective mirror 11 and second reflective mirror 12) described later. The display light L is then directed toward the viewer PS seated in the vehicle facing the instrument panel IP, enabling the viewer PS to visually recognize the display image represented by the display light L.

[0070] Figure 1 This indicates the state in which the visual observer PS visually recognizes the instrument panel IP, with a real image RI appearing close to the instrument panel IP (between the visual observer PS and the instrument panel IP). The specific display distance is, for example, approximately 500 mm to 800 mm from the eye. The real image RI is used to display an operation screen, for example, when the system is activated or the visual observer PS's posture is detected. Figure 2 This indicates a state in which the visual observer PS is visually observing a virtual image VI that is recessed into the instrument panel IP. The specific display distance is, for example, approximately 2 to 3 meters from the eye. The virtual image VI displays entertainment content, such as a movie or game, selected by the visual observer PS via the real image RI. The virtual image VI then switches to the real image RI when the content ends or when the visual observer PS's gesture is detected.

[0071] In addition, the visual observer PS includes the driver of the vehicle C or the person sitting in the passenger seat, and the instrument panel IP refers to the entire front surface of the vehicle (for example, including the area in front of the driver's seat where instruments are configured, the area between the driver's seat and the passenger seat where displays or equipment are configured, the area of ​​the control panel in front of the passenger seat, etc.).

[0072] In addition, as for the optimal display position or display size of the real image RI or the virtual image VI, for example, by visually confirming the virtual image surface using a head-mounted display while actually riding in the vehicle C, the real image RI or the virtual image VI can be visually confirmed without burden, or it can be evaluated from various perspectives, such as whether the willingness to use it is increased.

[0073] Explain in detail Figure 1 and Figure 2 The structure of the display device 1 is shown. Figure 3 1 is a diagram showing a layout when a real image is visually recognized in the display device 1 according to the present embodiment. Figure 4 It is a diagram showing a layout when a virtual image is visually recognized in the display device 1 according to the present embodiment.

[0074] exist Figure 3 and Figure 4 In the embodiment, the display unit 10 is arranged at a position below the display device 1. This arrangement allows the area below the display device 1 to be narrowed and compacted, and allows efficient layout by utilizing the shape of the instrument panel IP.

[0075] Here, the structure of the display unit 10 will be described in further detail. Figure 5 1 is a diagram showing the structure of the display unit 10 of the display device 1 according to this embodiment. Figure 5 As shown, the display unit 10 includes a light source 111, such as a white LED; a condenser lens 112, located behind the light source 111, to condense the light emitted from the light source 111; a lenticular lens 113 and a diffuser 114, located behind the condenser lens 112, to uniformize the brightness of the light condensed by the condenser lens 112; a liquid crystal display 115, located on the rear side, to generate display light L for the display image visually recognized by a viewer PS; and a polarizing plate 116, which transmits only light of a specific vibration direction among the various vibration directions of the display light L. Here, the polarizing plate 116 is located so as to produce, for example, P-polarized light (first linearly polarized light) relative to the polarization selection module 20 described later. These various components constituting the display unit 10 are fixed to and supported by a housing 117.

[0076] The housing 117 is connected to a rod-shaped height adjustment portion 118. The height adjustment portion 118 (advance and retreat drive portion) is subjected to a twisting process and can be rotated in the direction of arrow a by, for example, a stepping motor or the like. A connection portion 119 subjected to a twisting process is joined to the housing 117, and the twisting portion of the connection portion 119 is connected to the twisting portion of the height adjustment portion 118 in a mutually engaged state. That is, the position of the display unit 10 can be displaced in the up and down direction (the normal direction that is approximately orthogonal to the emission direction of the display light L of the display unit 10 or the surface direction of the liquid crystal display 115) by the rack and pinion mechanism, that is, the display unit 10 can be displaced in a manner that advances and retreats relative to the polarization selection module 20, thereby adjusting the display quality of the display image visually recognized by the visual observer PS.

[0077] exist Figure 3 and Figure 4 In the display device 1, the display unit 10 emits display light L representing a display image visually recognized by a viewer PS from the bottom side of the display device 1 toward the polarization selection module 20 disposed above it. The polarization selection module 20 is a set of plate-like components that has the property of reflecting light of one polarization and transmitting light of another polarization orthogonal to the first polarization. Here, the polarization selection module 20 is configured to transmit light of P polarization (first linear polarization) and reflect light of S polarization (second linear polarization).

[0078] The polarization selection module 20 has a pitch axis along the width of the vehicle C and a rotation axis S at the center of the polarization selection module 20. The polarization selection module 20 is driven to rotate about the rotation axis S by a rotation drive unit 21, such as a motor, to change the angle relative to the optical path of the display light L.

[0079] exist Figure 3 and Figure 4 In the display unit 10, a first reflector 11 is arranged at a first angular position along the circumference around the rotation axis S (a position above the instrument panel IP) that reflects the display light L. In addition, a second reflector 12 is arranged at a second angular position different from the first angular position (a position on the back side of the instrument panel IP as viewed from the visual observer PS or a position approximately perpendicular to the first angular position around the rotation axis S) that reflects the display light L. The first reflector 11 and the second reflector 12 are arranged at positions that reflect the display light L toward the polarization selection module 20. A heat sink 50 for heat dissipation is arranged further below the display unit 10 (on the back side of the light source 111). In addition, the first reflector 11 and the second reflector 12 may be plane mirrors, but are preferably concave mirrors. In particular, in order to display the real image RI, it is necessary for the second reflector 12 to be a concave mirror.

[0080] The control unit 30 controls the content and display mode of the display image displayed on the display unit 10 , controls the rotation angle of the rotation drive unit 21 , and controls the height adjustment of the height adjuster 118 .

[0081] In addition, Figure 3 In this case, the position of the optical focus F1 (first optical focus) of the optical component consisting of the first reflector 11, the second reflector 12, and the polarization selection module 20 is set so that it is 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 selection module 20 and the display unit 10. Furthermore, the polarization selection module 20 is positioned at an angle (first rotational position) such that the upper portion of the polarization selection module 20 (the region above the rotation axis S) is located on the viewer's side. This creates a state where one surface of the polarization selection module 20 faces the two first reflectors 11 and the second reflector 12. Consequently, the display light L emitted from the display unit 10 passes through the polarization selection module 20, is reflected and inverted by the first reflector 11, is reflected by the polarization selection module 20 in a direction substantially perpendicular to the back side of the viewer PS (the direction in which the second reflector 12 is located), is reflected and inverted by the second reflector 12, and then passes through the polarization selection module 20 again, allowing the viewer PS to visually recognize a real image RI in front of the instrument panel IP.

[0082] In addition, Figure 4 In the case of , the position of the optical focus F2 (second optical focus) of the optical component composed of the first reflector 11 and the polarization selection module 20 is set so as to be closer to the side opposite to the opening 17 than 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. In addition, here, the angle of the polarization selection module 20 is such that the lower part of the polarization selection module 20 (the area below the rotation axis S) is located on the visual observer side (second rotation position), that is, with Figure 3 In the case of the polarization selection module 20, the polarization selection module 20 is arranged at an angle of approximately 90 degrees, so that one surface of the polarization selection module 20 faces the first reflector 11, and the other surface faces the second reflector 12. Thus, the display light L emitted from the display unit 10 passes through the polarization selection module 20, is reflected and inverted by the first reflector 11, and is reflected by the polarization selection module 20 toward the front side of the visual observer PS, that is, toward the side of the visual observer PS in a direction approximately perpendicular to the visual observer PS, so that the visual observer PS visually recognizes the virtual image VI on the back side of the instrument panel IP.

[0083] In this way, by adopting an optical system in which the display light L passes through the same optical path twice, the optical path length can be ensured and the required volume can be reduced compared to the case of adopting an optical system in which the display light L passes through the same optical path only once.

[0084] In addition, Figure 3In the embodiment, the second reflector 12 is preferably configured so that the display light L reflected by the second reflector 12 and transmitted through the polarization selection module 20 toward the viewer PS is directed in a different direction than the light Lr directly reflected by the polarization selection module 20 from the display light L emitted from the display unit 10. This configuration prevents the light directly reflected by the polarization selection module 20 from entering the eyes of the viewer PS and being visually recognized as an unintended image (stray light). In this case, the configuration of the second reflector 12 is modified within a range that does not significantly degrade the imaging performance of the displayed image of the display light L, and this range can also be determined based on the required specifications.

[0085] In addition, the inclination of the polarization selection module 20 is preferably such that the incident angle ( Figure 3 The angle θ shown is set to be close to the Brewster angle (the angle at which the reflectivity of incident P-polarized light is zero or extremely low). This arrangement can minimize stray light.

[0086] Next, we will explain in detail Figure 3 and Figure 4 In each structure, the process of imaging the display image of the real image RI or the virtual image VI. Figure 6 1 is a diagram showing the structure of the polarization selection module 20 in the display device 1 according to the present embodiment. Figure 7 1 is a diagram illustrating a transition of the polarization state of the display light L when the real image RI is visually recognized in the display device 1 according to the present embodiment. Figure 8 1 and 2 are diagrams for explaining the transition of the polarization state of the display light L when the virtual image VI is visually recognized in the display device 1 according to the present embodiment.

[0087] Figure 6 The polarization selection module 20 shown is formed by stacking a substrate 201, a polarization selection plate 203, and a 1 / 4λ plate 202 in this order. The substrate 201 is a base for attaching and supporting various components, and is formed of glass such as optical glass or acrylic glass. In addition, considering the large size of the display device 1 or the influence of the vibration of the vehicle C, tempered glass or the like can be used. The reflectivity of glass is generally not 100%, and it will reflect a part of the light. In order to cope with this situation, an AR (Anti-Reflection) film can be attached to the lower part of the substrate 201 (the side where the display unit 10 is configured) or a coating can be applied to transmit a large amount of light.

[0088] The 1 / 4λ plate 202 is a film-like component that has the function of delaying the phase of polarized light by π / 4. This function can 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. The type of circularly polarized light to be converted depends on how the 1 / 4λ plate 202 is arranged. Figure 7 and Figure 8 In the embodiment, the P-polarized light (linearly polarized light) is converted into the left circularly polarized light (first circularly polarized light) and the left circularly polarized light (first circularly polarized light) is converted into the P-polarized light (linearly polarized light).

[0089] The polarization selection plate 203 is a component that has the property of reflecting specific circularly polarized light (e.g., right-handed circularly polarized light (second circularly polarized light)) and transmitting circularly polarized light in the opposite direction (e.g., left-handed circularly polarized light (first circularly polarized light)). For example, a liquid crystal polymer layer is known. The liquid crystal polymer layer has the property of effectively reflecting right-handed circularly polarized light and effectively transmitting left-handed circularly polarized light. Specifically, the reflectivity of right-handed circularly polarized light is known to be approximately 70%, while the transmittance of left-handed circularly polarized light is known to be approximately 90%. Furthermore, materials are known that have the property of re-reflecting right-handed circularly polarized light as right-handed circularly polarized light, a property not found in conventional mirrors, etc.

[0090] Description Figure 6 The function of the polarization selection module 20 shown is premised on Figure 7 and Figure 8 The polarization state is converted until the images are respectively imaged and displayed.

[0091] exist Figure 7In the figure, the polarization selection module 20 is configured so that the 1 / 4λ plate 202 is located closer to the display unit 10 (on the lower side of the drawing) than the polarization selection plate 203. First, the display light L of P polarization 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 polarization to left circular polarization by passing through the 1 / 4λ plate 202, and then passes through the polarization selection plate 203 and travels to the first reflector 11. The left circularly polarized display light L is reflected by the first reflector 11, and the polarization becomes right circular polarization. In addition, it is a well-known physical phenomenon that the direction of circular polarization on a mirror surface is reversed. Next, the display light L of right circular polarization is reflected by the polarization selection plate 203 and travels to the second reflector 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 circular polarization. Then, the right circularly polarized display light L is reflected by the second reflector 12 and becomes left circularly polarized light. According to the characteristics of the polarization selection plate 203, the left circularly polarized display light L is transmitted through the polarization selection plate 203. The left circularly polarized display light L that has transmitted the polarization selection plate 203 is converted into P polarized light by the 1 / 4λ plate 202 and emitted to the outside of the display device 1. Figure 1 and Figure 3 As shown, the visual observer PS is in a state where the real image RI can be visually recognized.

[0092] exist Figure 8 In, with Figure 7 The same as the situation above, the polarization selection module 20 is configured so that the 1 / 4λ plate 202 is located closer to the display unit 10 (the lower side of the drawing) than the polarization selection plate 203. First, the display light L of P polarized light is emitted from the display unit 10 and is incident on the polarization selection module 20. At this time, the polarization of the display light L is converted from P polarized light to left circularly polarized light by passing through the 1 / 4λ plate 202, and passes through the polarization selection plate 203 to go to the first reflector 11. The display light L of left circularly polarized light is reflected by the first reflector 11, so that the polarization becomes right circularly polarized light. Then, according to the characteristics of the polarization selection plate 203 mentioned above, the display light L of right circularly polarized light is reflected by the polarization selection plate 203 and is directly emitted to the outside of the display device 1. Thus, as shown in FIG. Figure 2 and Figure 4 As shown, the visual observer PS is in a state where the virtual image VI can be visually recognized.

[0093] Furthermore, regarding the internal layout of the display device 1, the display unit 10 can be positioned at the top and the first reflector 11 at the bottom. In this case, the polarization state of the display light L is converted using the same principle as described above. For example, in the above description, the polarization selection module 20 rotates to tilt toward the right in the drawing (toward the second reflector 12) when the real image RI is visually recognized, and to tilt toward the left in the drawing (toward the first reflector 11) when the virtual image VI is visually recognized. However, in the case of an upside-down rotation, the tilt is reversed.

[0094] Thus, the display device 1 involved in this embodiment comprises: a display unit 10, which has a light source 111, which 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, which reflects a second linearly polarized light (for example, S polarized light) orthogonal to the first linear polarized light and transmits the first linear polarized light; a rotation drive unit 21, which rotates the polarization selection module 20 around the rotation axis S, thereby being able to change the angle of the optical path relative to the display light L; a control unit 30, which controls at least the rotation drive unit 21; and a first reflector 11 and a second reflector 12, which are arranged at a position that reflects the display light L toward the polarization selection module 20, the first reflector 11 being set at a first angular position along the circumference around the rotation axis S (for example, a position above the instrument panel IP), and the second reflector 12 being set at a position relative to the first angular position. The control unit 30 controls the rotation drive unit 21 to rotate the polarization selection module 20 to the first rotation position for displaying the real image RI when the real image RI is visually confirmed. When the display light L emitted from the display unit 10 is transmitted and incident on the display light L reflected by the first reflector 11, the direction of the display light L reflected and emitted is directed to the second reflector 12, and the direction of the display light L reflected by the second reflector 12 after being transmitted is directed to the opening 17. When the polarization selection module 20 is rotated to the second rotation position for displaying the virtual image VI, when the virtual image VI is visually confirmed, when the display light L emitted from the display unit 10 is transmitted and incident on the display light L reflected by the first reflector 11, the direction of the display light L reflected and emitted is directed to the opening 17 without passing through the second reflector 12.

[0095] Thus, when the visual observer PS visually confirms the real image RI, the polarization selection module 20 is rotated to the first rotation position, thereby achieving a relatively long optical path length on the path of the display unit 10, the polarization selection module 20, the first reflector 11, the polarization selection module 20, the second reflector 12, the polarization selection module 20 and the opening 17, so that the real image RI can be visually confirmed on the near front side of the instrument panel IP from the visual observer PS.

[0096] When the visual observer PS visually confirms the virtual image VI, the polarization selection module 20 is rotated to the second rotation position, thereby achieving a relatively short optical path length on the path of the display unit 10, the polarization selection module 20, the first reflector 11, the polarization selection module 20 and the opening 17, so that the virtual image VI can be visually confirmed on the inner side of the instrument panel IP from the visual observer PS.

[0097] Furthermore, when visually observing the real image RI, by forming an optical path that passes through the same position (polarization selection module 20) twice, the optical path length can be increased without increasing the size of the entire display device 1. As a result, the device can be mounted more easily within the instrument panel IP, which is subject to space constraints.

[0098] In addition, the polarization selection module 20 has: a 1 / 4λ plate 202, which is capable of converting linearly polarized light into a first circularly polarized light (e.g., left circularly polarized light) and converting the first circularly polarized light into linearly polarized light; and a polarization selection plate 203, which transmits the first circularly polarized light and reflects a second circularly polarized light (e.g., right circularly polarized light) in a direction opposite to that of the first circularly polarized light.

[0099] Thus, when the viewer PS visually recognizes the real image RI, first linearly polarized light (e.g., P-polarized light) emitted from the display unit 10 passes through the polarization selection module 20 positioned in the first rotational position, is converted by the ¼λ plate 202 into first circularly polarized light (e.g., left-handed circularly polarized light), then reflected by the first reflector 11 into second circularly polarized light (e.g., right-handed circularly polarized light) and inverted. The inverted second circularly polarized light is further reflected by the polarization selection plate 203 of the polarization selection module 20 and emitted by the second reflector 12. The emitted second circularly polarized light is reflected by the second reflector 12 into first circularly polarized light, inverted, passes through the polarization selection plate 203 of the polarization selection module 20, and is converted by the ¼λ plate 202 into first linearly polarized light before traveling to the opening 17. This achieves a relatively long optical path length, allowing the viewer PS to visually recognize the real image RI closer to the front of the instrument panel IP as viewed from the front of the instrument panel IP.

[0100] When the viewer PS visually recognizes the virtual image VI, the first polarized light emitted from the display unit 10 passes through the polarization selection module 20 in the second rotational position. After being converted into first circularly polarized light (e.g., left-handed circularly polarized light) by the ¼λ plate 202, it is reflected by the first reflector 11 and then inverted into second circularly polarized light (e.g., right-handed circularly polarized light). The inverted second circularly polarized light is reflected by the polarization selection plate 203 and travels toward the opening 17. This allows for a relatively short optical path length, allowing the viewer PS to visually recognize the virtual image VI from the rear side of the instrument panel IP.

[0101] Furthermore, the ¼λ plate 202 is located closer to the display unit 10 than the polarization selection plate 203 regardless of whether the polarization selection module 20 is in the first or second rotational position.

[0102] In addition, when the polarization selection module 20 is located in the first rotation position, the optical focus F1 of the imaging optical system including the first reflector 11, the second reflector 12 and the polarization selection module 20 is located on the side of the opening 17 closer to the display unit 10 along the optical path of the display light L. When the polarization selection module 20 is located in the second rotation position, the optical focus F2 of the imaging optical system including the first reflector 11 and the polarization selection module 20 is located on the side of the display unit 10 opposite to the opening 17 along the optical path of the display light L. Therefore, simply by switching the polarization selection 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 for visual confirmation.

[0103] In addition, since there is further a height adjustment unit 118 for moving the display unit 10 forward and backward relative to the polarization selection module 20, when switching between the real image RI display and the virtual image VI display, the display can be made clear by appropriately adjusting the distance between the display unit 10 and the polarization selection module 20, thereby improving the display quality.

[0104] Furthermore, the above configuration improves transmittance and reflectance compared to a case where a half mirror is used, thereby improving brightness efficiency and reducing the amount of light emitted from the display unit 10, that is, reducing power consumption. Furthermore, due to the high transmittance and reflectance, the brightness of unexpected light is also reduced, which can reduce stray light.

[0105] Furthermore, the display device 1 according to this embodiment is mounted in the glove box on the passenger side, allowing a visual observer PS seated in the passenger seat to visually recognize both a real image RI and a virtual image VI. For example, on a screen for selecting which content to view, the real image RI can be displayed so as to appear near the glove box. When content playback actually begins, the virtual image VI can be displayed so as to appear below the glove box. The content being reproduced here can include, for example, entertainment content unrelated to driving (e.g., games or movies).

[0106] (Second embodiment of the present invention)

[0107] The display device 1 according to this embodiment will be described with reference to the accompanying drawings. While the display device 1 according to the first embodiment includes the polarization selection module 20 with the ¼λ plate 202, the display device 1 according to this embodiment includes the ¼λ plate 202 in the first and second reflective mirrors 11 and 12. In this embodiment, overlapping descriptions with those in the first embodiment are omitted.

[0108] Figure 9 1 is a diagram showing the configuration of the polarization selection module 20, the first reflecting mirror 11, and the second reflecting mirror 12 in the display device 1 according to this embodiment. Figure 10 1 is a diagram illustrating a transition of the polarization state of the display light L when the real image RI is visually recognized in the display device 1 according to the present embodiment. Figure 11 1 and 2 are diagrams for explaining the transition of the polarization state of the display light L when the virtual image VI is visually recognized in the display device 1 according to the present embodiment.

[0109] like Figure 9 As shown, the polarization selection module 20 has only the polarization selection plate 203 attached to the substrate 201. In addition, a first 1 / 4λ plate 202a and a second 1 / 4λ plate 202b are attached to the surfaces of the first reflecting mirror 11 and the second reflecting mirror 12, respectively.

[0110] Figure 9 The polarization selection plate 203 shown has the property of transmitting a specific linearly polarized light and effectively reflecting orthogonal linearly polarized light. A known example is a cold mirror film (CMF). For example, a CMF has the property of transmitting P-polarized light and reflecting S-polarized light. Specifically, the transmittance of P-polarized light and the reflectance of S-polarized light are known to be approximately 80%.

[0111] In addition, Figure 9In the embodiment, the first reflecting mirror 11 and the first ¼λ plate 202a are arranged so that when the display light L which is P-polarized light is reflected by the first reflecting mirror 11 with respect to the polarization selection module 20 and is incident again on the polarization selection module 20, it is incident as S-polarized light. The second reflecting mirror 12 and the second ¼λ plate 202b are arranged so that when the display light L which is S-polarized light is reflected by the second reflecting mirror 12 with respect to the polarization selection module 20 and is incident again on the polarization selection module 20, it is incident as P-polarized light.

[0112] Description Figure 9 In the structure shown, Figure 10 and Figure 11 The polarization state is converted until the images are respectively imaged and displayed.

[0113] exist Figure 10 In the example, 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, since the polarization selection plate 203 transmits P-polarized light, the display light L directly travels to the first reflector 11. It is then converted from P-polarized light to left circularly polarized light by the first ¼λ plate 202a. It is then reflected by the first reflector 11 to become right circularly polarized light. It is then converted again by the first ¼λ plate 202a to linearly polarized light, which then enters the polarization selection module 20. The linearly polarized light, which then reflects off the polarization selection plate 203 of the polarization selection module 20, travels to the second reflector 12. It is then converted from S-polarized light to right circularly polarized light by the second ¼λ plate 202b. It is then reflected by the second reflector 12 to become left circularly polarized light. It is then converted again by the second ¼λ plate 202b to linearly polarized light, which then enters the polarization selection module 20. Then, the display light L passes through the polarization selection module 20 and is emitted outside the display device 1 , thereby achieving a state in which the real image RI can be visually recognized by the viewer PS.

[0114] In addition, Figure 11 In the embodiment, first, the display light L of P polarized light is emitted from the display unit 10 and enters the polarization selection module 20, and the display light L goes directly to the first reflector 11. Thereafter, the display light L is converted from P polarized light to left circularly polarized light by the first 1 / 4λ plate 202a, reflected by the first reflector 11 to become right circularly polarized light, and again converted by the first 1 / 4λ plate 202a to linearly polarized light of S polarized light and enters the polarization selection module 20. Then, according to the characteristics of the polarization selection plate 203 described above, the display light L of S polarized light is reflected by the polarization selection plate 203 and directly emitted to the outside of the display device 1. Thus, a state is achieved in which the virtual image VI can be visually recognized by the visual observer PS. In addition, Figure 10 and Figure 11In the figure, for the sake of convenience, the first 1 / 4λ plate 202a and the second 1 / 4λ plate 202b are described as being on planes separated from the first reflector 11 and the second reflector 12, respectively. However, in reality, Figure 9 As shown, they are stacked adjacent to the first reflector 11 and the second reflector 12, respectively.

[0115] Thus, in the display device 1 involved in this embodiment, there are a first 1 / 4λ plate 202a and a second 1 / 4λ plate 202b on the polarization selection module 20 side of the first reflector 11 (the surface of the first reflector 11) and the polarization selection module 20 side of the second reflector 12 (the surface of the second reflector 12), which convert the first linear polarized light (for example, P polarized light) into the first circular polarized light (for example, left circular polarized light) and convert the first circular polarized light into the first linear polarized light, and convert the second linear polarized light (for example, S polarized light) into the second circular polarized light (for example, right circular polarized light) and convert the second circular polarized light into the second linear polarized light, respectively. The polarization selection module 20 has a polarization selection plate 203 that transmits the first linear polarized light and reflects the second linear polarized light orthogonal to the first linear polarized light.

[0116] Thus, when the observer PS visually recognizes the real image RI, 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 positioned in the first rotational position. It is then converted into first circularly polarized light (e.g., left-handed circularly polarized light) by the first ¼λ plate 202a located on the polarization selection module 20 side (surface side) of the first reflector 11. It is then reflected by the first reflector 11 as second circularly polarized light (e.g., right-handed circularly polarized light) and inverted. The inverted 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. It is then reflected by the polarization selection plate 203 of the polarization selection module 20 and emitted toward the second reflector 12. The emitted second linearly polarized light is then converted into second circularly polarized light by the second ¼λ plate 202b located on the polarization selection module 20 side (surface side) of the second reflector 12. It is then reflected by the second reflector 12 as first circularly polarized light and inverted. After being inverted, the first circularly polarized light is further converted into first linearly polarized light by the second ¼λ plate 202b on the polarization selection module 20 side, then passes through the polarization selection plate 203 and travels toward the opening 17. This allows for a relatively long optical path length, allowing the real image RI to be visually recognized from the viewer PS closer to the front than the instrument panel IP.

[0117] Furthermore, when the viewer PS visually recognizes the virtual image VI, 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 positioned in the second rotational position. It is then converted into first circularly polarized light (e.g., left-handed circularly polarized light) by the first ¼λ plate 202a located on the polarization selection module 20 side (front side) of the first reflector 11. The converted light is then reflected by the first reflector 11 as second circularly polarized light (e.g., right-handed circularly polarized light) and inverted. The inverted 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. The light is then reflected by the polarization selection plate 203 of the polarization selection module 20 and travels toward the opening 17. This allows for a relatively short optical path length, allowing the virtual image VI to be visually recognized from the back side of the instrument panel IP as viewed from the viewer PS.

[0118] Furthermore, by adopting the above-described configuration, it is possible to reduce the deviation in color tone after passing through the optical system, compared to the display device 1 according to the first embodiment.

[0119] Furthermore, since the polarization of the display light L finally emitted is linearly polarized light, it is easy to cut off unintended light by a polarizing plate or the like.

[0120] Furthermore, the above-described structure improves transmittance and reflectance compared to a case where a half-mirror is used, thereby improving brightness efficiency and reducing the amount of light emitted from the display unit 10, that is, reducing power consumption. Furthermore, due to the high transmittance and reflectance, the brightness of unexpected light is also reduced, which can reduce stray light.

[0121] (Other embodiments of the present invention)

[0122] In the display device 1 according to the first embodiment, the feasibility of displaying the real image RI and the virtual image VI will be described using specific numerical values. Figure 12 The liquid crystal display 115 is arranged on the left side of the reflector system. The liquid crystal display 115, the first reflector 11 and the second reflector 12 are arranged in what positional relationship so as to display the real image RI. Figure 12 In the figure, the positive direction is defined as light traveling from the left (the liquid crystal display 115 side) to the right. Furthermore, the curvature radius of the boundary surface is defined as a positive radius when the convex surface faces the left, and a negative radius when the convex surface faces the right. Furthermore, in the height direction, the positive direction is defined as the direction above the paper (the symbol side), and the negative direction is defined as the direction below the paper.

[0123] exist Figure 12In the embodiment, the polarization selection module 20 is located in the first rotation position. For example, the curvature radius of the first reflector 11 is set to -700 mm, and the curvature radius of the second reflector 12 is set to 300 mm, so that the second reflector 12 is located at a distance of -220 mm from the first reflector 11. The liquid crystal display 115 is positioned 250 mm away from the first reflector 11.

[0124] In this configuration of the optical system, since the liquid crystal display 115 is located to the left of the optical focus F1 of the optical system, it can be seen that the light emitted from the liquid crystal display 115 forms a real image RI.

[0125] In addition, the optical system with the polarization selection module 20 located at the second rotation position is Figure 13 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. Therefore, it can be seen that the light emitted from the liquid crystal display 115 forms a virtual image VI.

[0126] Furthermore, the above discussion is solely based on paraxial theory. However, when the size of the image to be displayed increases, the angle between the light and the optical axis is increased. Therefore, discussions regarding imaging performance cannot be solely based on paraxial theory, and various aberrations, including Seidel's five aberrations, may occur within this context. In this case, it is preferable to make the first reflector 11 and the second reflector 12 have a shape more complex than a spherical surface to minimize aberration correction. For example, they can be aspherical or free-form surfaces.

[0127] In addition, for example Figure 14 As shown, a lens having a light-collecting function may be inserted between the display unit 10 and the polarization selection module 20 or between the polarization selection module 20 and the viewer PS along the optical path of the display light L. Figure 14 1 is a diagram showing an example of a structure in which a lens is inserted into the optical path of the display light L in the display device 1 according to this embodiment. Figure 14 Inserting the lenses 171 and 172 as shown can enlarge the real image RI and virtual image VI displayed by the first and second reflecting mirrors 11 and 12. That is, the sizes of the first and second reflecting mirrors 11 and 12 required to display an image of a specific size can be reduced.

[0128] If lenses 171 and 172 are inserted as described above, chromatic aberration may sometimes occur. This phenomenon is caused by the property that the refractive index of the material used for lenses 171 and 172 depends on the wavelength of light. When this phenomenon occurs, since the imaging positions of light of different wavelengths are different, the outline of the image may sometimes look like a rainbow, which impairs the display quality. To cope with this situation, the lens can be made to have a chromatic aberration function. In order to perform achromatic aberration, it is known that at least two types of glass or resin with different Abbe numbers v need to be applied to lenses with positive power (the function of focusing light) and negative power (the function of diverging light).

[0129] Here, the Abbe number is an index of how easily the refractive index changes with wavelength. When the refractive index of d-line (587.56 nm: corresponding to orange light) is set to n d , the refractive index of C line (665.27nm: equivalent to red light) is set to n C , the refractive index of F line (486.13nm: equivalent to blue light) is set to n F When , the Abbe number v is given by:

[0130] (Mathematical formula 1)

[0131]

[0132] Definition. 1 / v is called the dispersion of the material. A larger value indicates a greater effect of the refractive index change on each wavelength, while a smaller value indicates a smaller effect of the refractive index on each wavelength.

[0133] Materials having different Abbe numbers are used to reduce chromatic aberration, and a combination of lenses called a doublet lens is widely known as a combination that achieves this. Figure 15 This is a diagram showing the structure of a doublet lens. A doublet lens is made by making lenses of materials with different refractive indices and pressing them together. For example, Figure 15 As shown, the first lens DL1 on the left is made of a first material and is shaped like a convex lens, and the second lens DL2 on the right is made of a second material and has a concave surface with the same curvature radius as the right side of the first lens DL1 on the left, and a flat surface on the right side. A doublet lens is completed by placing the first lens DL1 and the second lens DL2 in close contact. At this time, of the first material and the second material, the first material is arranged at the front section (incident side), and the second material is arranged at the back section (exit side), the Abbe number of the first material is set to v1, and the Abbe number of the second material is set to v2. At this time, the configuration is such that v1>v2, so that chromatic aberration can be effectively removed. In addition, since in Figure 15The lens shown has positive power, so the light passing through the lens is refracted in a focusing direction, which can help to miniaturize the first reflector 11 and the second reflector 12 .

[0134] By placing a lens with this property as Figure 14 By arranging the lenses 171 and 172 as shown in the example, an optical system that suppresses chromatic aberration can be effectively constructed.

[0135] In addition, the lens 171 disposed near the ejection port 17 is as shown in FIG. Figure 16 As shown, a lens assembly can be configured with multiple lenses. To reduce the number of components, if a single lens is desired to image (focus) light between the glove box surface and the visual observer PS, the lens thickness becomes larger. A thick convex lens increases manufacturing difficulty, so it is preferably as small (thin) as possible. Therefore, in the present invention, three lenses of varying thicknesses are configured.

[0136] The three lenses consist of a third lens DL3 arranged on the innermost side (polarization selection module 20 side), a fifth lens DL5 arranged on the outermost side (opening 17 side), and a fourth lens DL4 arranged between the two. The central surface DL3a, which is the central part of the inner surface of the third lens DL3, is a convex surface (negative refractive index), and the peripheral surface DL3b, which is the peripheral part of the center, is a concave surface (positive refractive index). This makes it possible to efficiently correct the distortion of the displayed image. The outer surface of the third lens DL3 is a convex surface. The inner and outer surfaces of the fourth lens DL4 and the fifth lens DL5 are all convex surfaces. In addition, the convex surfaces of the third lens DL3, the fourth lens DL4, and the fifth lens DL5 are all different. Here, the convex surface refers to a hyper-torus aspheric surface or a free-form surface.

[0137] By using three lenses in this manner, light is gradually focused, ultimately converging at the eye of the viewer PS. Furthermore, the third and fourth lenses DL3 and DL4, located on the inner side, are colorless and transparent, while the fifth lens DL5, located on the outer side, is colored a smoky (translucent black) color to prevent introspection within the frame. This allows the lens to function as a lens while also preventing introspection.

[0138] (Appendix 1-1)

[0139] A display device is provided in a dashboard of a vehicle, and emits display light from an emission port so that a real image of a display image displayed by the display light can be visually confirmed, wherein the display device comprises:

[0140] a display unit including a light source, emitting light from the light source as first linearly polarized light and displaying the display image;

[0141] a polarization selection module that reflects a second linearly polarized light orthogonal to the first linearly polarized light and transmits the first linearly polarized light; and

[0142] a first reflecting mirror and a second reflecting mirror, which are arranged at positions reflecting the display light toward the polarization selection module;

[0143] The polarization selection module is configured so that after the display light emitted from the display portion is transmitted and enters the display light reflected by the first reflector, the direction of the display light reflected and emitted is directed toward the second reflector, and the direction of the display light after the display light reflected by the second reflector is transmitted is directed toward the emission port.

[0144] (Note 2)

[0145] In addition, the polarization selection module has:

[0146] a ¼λ plate capable of converting linearly polarized light into first circularly polarized light and converting the first circularly polarized light into the linearly polarized light; and

[0147] A polarization selection plate transmits the first circularly polarized light and reflects a second circularly polarized light having a direction opposite to that of the first circularly polarized light.

[0148] (Appendix 3-1)

[0149] In addition, the ¼λ plate of the polarization selection module is located closer to the display unit than the polarization selection plate.

[0150] (Note 4)

[0151] In addition,

[0152] A 1 / 4λ plate is further provided on the polarization selection module side of the first reflector and the second reflector, the 1 / 4λ plate converting the first linear polarized light into the first circular polarized light and the first circular polarized light into the first linear polarized light, converting the second linear polarized light into the second circular polarized light and the second circular polarized light into the second linear polarized light,

[0153] The polarization selection module has:

[0154] A polarization selection plate transmits the first linearly polarized light and reflects the second linearly polarized light.

[0155] (Note 5)

[0156] In addition, the first reflecting mirror and the second reflecting mirror are concave mirrors.

[0157] (Appendix 6-1)

[0158] In addition, a first optical focus of an imaging optical system including the first reflecting mirror, the second reflecting mirror, and the polarization selection module is located closer to the emission port than the display unit along the optical path.

[0159] (Note 7)

[0160] In addition, a plurality of lens components are provided between the polarization selection module and the emission port side.

[0161] (Note 8)

[0162] Furthermore, the lens member on the emission port side is colored.

[0163] (Appendix 1-2)

[0164] In addition, a display device for visually confirming a virtual image and the real image further comprises:

[0165] a rotation drive unit that rotates the polarization selection module around a rotation axis, thereby changing an angle relative to an optical path; and

[0166] a control unit that controls the rotation drive unit,

[0167] The first reflector is arranged at a first angular position along a circumferential direction around the rotation axis, and the second reflector is arranged at a second angular position different from the first angular position.

[0168] The control unit controls the rotation drive unit.

[0169] When the real image is visually confirmed, the polarization selection module is rotated to a first rotation position for real image display.

[0170] When visually confirming the virtual image, the polarization selection module is rotated to the second rotation position for displaying the virtual image, and after the display light emitted from the display unit is transmitted and incident on the display light reflected by the first reflector, the direction of the reflected and emitted display light goes to the emission port without passing through the second reflector.

[0171] (Appendix 3-2)

[0172] In addition,

[0173] In either the first rotational position or the second rotational position of the polarization selection module, the ¼λ plate is located closer to the display unit than the polarization selection plate.

[0174] (Appendix 6-2)

[0175] In addition,

[0176] When the polarization selection module is located at the first rotation position, a first optical focus of the imaging optical system including the first reflecting mirror, the second reflecting mirror, and the polarization selection module is located closer to the emission port than the display unit along the optical path.

[0177] When the polarization selection module is located at the second rotational position, a second optical focus of the imaging optical system including the first reflective mirror and the polarization selection module is located on the side of the display unit opposite to the emission port along the optical path.

[0178] (Note 9)

[0179] In addition, the device further comprises an advance / retract drive unit configured to advance / retract the display unit relative to the polarization selection module.

Claims

1. A display device provided in an instrument panel of a vehicle, wherein a real image of a display image represented by the display light is visually recognized by emitting display light from an emission port, characterized in that: The display device has: a display unit including a light source, the display unit emitting light from the light source as first linearly polarized light and displaying the display image; a polarization selection module that reflects a second linearly polarized light orthogonal to the first linearly polarized light and transmits the first linearly polarized light; as well as a first reflecting mirror and a second reflecting mirror, which are arranged at positions reflecting the display light toward the polarization selection module; The polarization selection module is configured to transmit the display light emitted from the display unit, direct the display light reflected by the first reflector into, reflected and emitted from, the display light toward the second reflector, and direct the display light reflected by the second reflector after being transmitted toward the emission port.

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

3. The display device according to claim 2, wherein: The ¼λ plate of the polarization selection module is located closer to the display unit than the polarization selection plate.

4. The display device according to claim 1, wherein A 1 / 4λ plate is further provided on the polarization selection module side of the first reflector and the second reflector, the 1 / 4λ plate converting the first linearly polarized light into the first circularly polarized light and the first circularly polarized light into the first linear polarized light, converting the second linearly polarized light into the second circularly polarized light, and converting the second circularly polarized light into the second linearly polarized light, The polarization selection module has: A polarization selection plate transmits the first linearly polarized light and reflects the second linearly polarized light.

5. The display device according to any one of claims 1 to 4, characterized in that The first reflecting mirror and the second reflecting mirror are concave mirrors.

6. The display device according to any one of claims 1 to 4, characterized in that A first optical focus of an imaging optical system including the first reflecting mirror, the second reflecting mirror, and the polarization selection module is located closer to the emission port than the display unit along the optical path.

7. The display device according to any one of claims 1 to 4, characterized in that A plurality of lens components are provided between the polarization selection module and the emission port side.

8. The display device according to claim 7, wherein: The lens member on the emission port side is colored.

Images