Image display device

Abstract

An image display device (100) comprises a first image projection unit (S) for irradiating a first image and a projection optical unit (G) for projecting the light of the first image in the direction of a viewpoint, and a rotation holding unit (CS) for holding the projection optical unit (G) so as to be rotatable laterally around a rotation axis (AX) so as to make the angle (θ) formed between the direction of travel of the light of the first image projected from the projection optical unit (G) and the direction of the central line of sight from the viewpoint variable.

Description

Technical Field

[0001] The present disclosure relates to an image display device, and in particular to an image display device that forms an image by superimposing a plurality of images in a depth direction of space. Background Art

[0002] Conventionally, as a device for displaying various information in a vehicle, an instrument panel that displays icons by lighting has been used. In addition, as the amount of information displayed increases, it has been proposed to embed an image display device in the instrument panel so that the image display device constitutes the entire instrument panel.

[0003] However, since the instrument panel is located below the vehicle's windshield, the driver must shift their gaze downward while driving to visually confirm the information displayed on the instrument panel, which is not ideal. Therefore, a head-up display (hereinafter referred to as HUD) has been proposed that projects an image onto the windshield, allowing the driver to read the information while visually confirming the direction ahead of the vehicle (see, for example, Patent Document 1). This type of HUD requires an optical device to project the image onto a large area of ​​the windshield, and miniaturization and weight reduction of the optical device are desired.

[0004] On the other hand, as an image display device that projects light using a small optical device, a head-mounted HUD in the shape of glasses is known (see, for example, Patent Document 2). In a head-mounted HUD, light emitted from a light source is directly directed to the user's eyes, projecting an image onto the user's retina.

[0005] Prior art literature

[0006] Patent Literature

[0007] Patent Document 1: Japanese Patent Application Publication No. 2018-118669

[0008] Patent Document 2: Japanese Patent Application No. 2018-528446 Summary of the Invention

[0009] Problems that the invention will solve

[0010] However, while conventional head-mounted HUDs can display images superimposed on the background, the aerial image's position is fixed within the user's field of view, limiting the degree of freedom in display placement. Consequently, depending on the user's usage and preferences, the aerial image may be displayed in an inappropriate position, making it difficult to provide an appropriate visual experience.

[0011] Therefore, an object of the present disclosure is to provide an image display device that can change the position of an image projected in space and can increase the degree of freedom of the display position.

[0012] Means for solving problems

[0013] In order to solve the above-mentioned problems, the image display device disclosed in the present invention comprises: a first image projection unit, which irradiates a first image; and a projection optical unit, which projects the light of the first image toward the viewpoint, and comprises a rotation holding unit, which holds the projection optical unit so as to be able to rotate laterally around a rotation axis so that the angle θ formed by the direction of travel of the light of the first image projected from the projection optical unit and the central line of sight direction from the viewpoint can be changed.

[0014] In the image display device of the present disclosure, the projection optical unit is held by the rotation holding unit so as to be rotatable laterally. Therefore, the projection position of the first image projected from the image projection unit in the air can be changed, thereby increasing the degree of freedom of the display position.

[0015] Effects of the Invention

[0016] The present disclosure can provide an image display device that can change the position of an image projected in space and increase the degree of freedom of the display position. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic plan view of the image display device according to the first embodiment.

[0018] Figure 2 This is a photograph showing the propagation of a laser beam inside the waveguide.

[0019] Figure 3A Schematic diagram showing the difference in imaging direction due to angle when light is reflected an odd number of times inside the waveguide.

[0020] Figure 3B Schematic diagram showing the difference in imaging direction due to angle when light is reflected an odd number of times inside the waveguide.

[0021] Figure 4A Schematic diagram showing the difference in imaging direction due to angle when light is reflected an even number of times inside the waveguide.

[0022] Figure 4B Schematic diagram showing the difference in imaging direction due to angle when light is reflected an even number of times inside the waveguide.

[0023] Figure 5 These are photographs showing examples of image display devices.

[0024] Figure 6 These are photographs showing how the display position of the first image changes when the rotation angle is changed in the embodiment.

[0025] Figure 7 This is an optical path diagram of the image display device according to the second embodiment.

[0026] Figure 8 It is a schematic top view of the image display device.

[0027] Figure 9 This is a schematic perspective view showing changes in the imaging position when the rotary support portion is rotated in the image display device. DETAILED DESCRIPTION

[0028] (First embodiment)

[0029] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. Identical or equivalent components, members, and processes shown in the respective drawings are denoted by the same reference numerals, and duplicate descriptions are omitted as appropriate. Figure 1 FIG is a schematic top view of the image display device 100 of this embodiment. Figure 1 As shown, the image display device 100 includes a first image projection unit S (an example of an image projection unit), a lens unit L, a waveguide unit G, and a housing unit CS. The solid arrows in the figure schematically illustrate the path of light emitted from the first image projection unit S. Furthermore, the dashed arrows in the figure indicate the direction directly in front of the user's visual horizontal position as the front center direction. Furthermore, the rectangular object represented by the double-dashed line in the figure is a virtual line when the waveguide unit G is rotated by an angle θ, as described later.

[0030] The shell CS is a frame that houses and holds each part. Figure 1 In the illustrated example, the housing CS houses the first image projection unit S, the lens unit L, and one end of the waveguide unit G within the housing CS. Furthermore, the housing CS rotatably holds one end of the waveguide unit G about a rotation axis AX. The housing CS corresponds to the rotation holding unit in the present disclosure. The structure for rotatably holding the waveguide unit G within the housing CS is not particularly limited; for example, a structure in which a support shaft provided in the waveguide unit G is axially supported by a bearing provided in the housing CS may also be employed.

[0031] The waveguide section G is a component that guides the light emitted from the first image projection section S and projects it in the direction of the user's viewpoint. The waveguide section G is equivalent to the projection optical section in the present disclosure. Figure 1As shown, one end of the waveguide portion G is held so as to be rotatable in the lateral direction with the rotation axis AX as the rotation center. The specific structure of the waveguide portion G is not limited, but it is preferably made of a transparent material that can visually confirm the background (H1 direction in the figure), and glass or resin materials can be used. Figure 1 In the example shown, the partial reflection portion HM is used as an optical element for extracting the light propagating through the waveguide portion G in the viewpoint direction, but a diffraction grating or the like may also be used.

[0032] The reflector M is an optical element provided inside the waveguide G and reflects light. Figure 1 In the example shown, the waveguide G is formed into a flat plate shape, and the reflective portion M is provided at an angle of 45 degrees relative to the in-plane direction of the waveguide G. However, the angle of the reflective portion M is not limited to 45 degrees relative to the in-plane direction of the waveguide G. The partial reflective portion HM is an optical element provided inside the waveguide G that reflects part of the light and transmits the remaining part. Figure 1 In the example shown, the partial reflection portion HM is provided at an angle of 45 degrees with respect to the in-plane direction of the waveguide portion G. However, the angle of the partial reflection portion HM is not limited to 45 degrees with respect to the in-plane direction of the waveguide portion G.

[0033] The first image projection unit S is a device that irradiates light constituting an image and projects the image toward the user's eyes (viewpoints). Figure 1 In the example shown, the first image projection unit S uses a laser light source unit that emits a laser beam, causes the light to enter the waveguide unit G via the lens unit L, and projects the light reflected by the reflection unit M and the partial reflection unit HM in the viewpoint direction.

[0034] The lens unit L is an optical element that adjusts the path of light emitted by the first image projection unit S. The specific configuration of the lens unit L is not limited; a known lens such as a collimating lens, a convex lens, a concave lens, or an aspheric lens for collimating a laser beam can be used. Furthermore, the lens unit L may include multiple lenses.

[0035] exist Figure 1 In the illustrated image display device 100, light including a first image projected from a first image projection unit S is incident on one end of a waveguide unit G via a lens unit L, and then incident on a reflective unit M at a predetermined angle. The light incident on the reflective unit M is reflected, propagates within the waveguide unit G, and is incident on the partially reflecting unit HM. The light is then reflected again by the partially reflecting unit HM, projected in the viewpoint direction, and visually recognized by the user.

[0036] exist Figure 1 In the figure, when the waveguide G is positioned at right angles to the viewing direction H1 as indicated by the solid line, light incident on the reflective portion M at a 45-degree angle enters the partially reflective portion HM at a 45-degree angle and reaches the viewpoint along the viewing direction H1. Therefore, the user visually recognizes the background in the viewing direction H1 as overlapping with the first image.

[0037] exist Figure 1 In the figure, when the waveguide portion G rotates by an angle θ as indicated by the virtual line, the incident angle of the light incident on the reflective portion M and the partially reflective portion HM changes, so that the light projected from the partially reflective portion HM toward the viewpoint becomes inclined at a predetermined angle relative to the line of sight H1. Therefore, the user visually recognizes the first image at a position offset to the side of the background in the line of sight H1. Here, the range of angle θ is preferably within a range of 25 degrees to the left and right of the user's viewpoint relative to the center of the front (-25 degrees or less, θ ≤ 25°). If the angle θ is greater than ±25°, the projection position of the first image changes significantly, making it difficult to maintain comfort when displaying it in superposition with the background.

[0038] Figure 2 This is a photograph showing the propagation of the laser beam inside the waveguide G. In the figure, the rectangle drawn with white dotted lines represents the cross section of the waveguide G, and the two arrows drawn with white dotted lines represent the direction of travel of the light outside the waveguide G. Figure 2 As shown, the laser beam is incident from the lower left in the figure to the position of the circle drawn by the white solid line. At this time, inside the waveguide G, the laser beam propagates to the right while being totally reflected by the main surface, and the light reflected by the partial reflection portion HM irradiates downward in the figure. The propagation of light inside the waveguide G is shown in FIG. Figure 2 As shown, therefore, by making Figure 1 The housing portion CS shown is rotated in the left-right direction to change the angle between the sight line direction H1 and the waveguide portion G, thereby changing the visual confirmation direction of the first image.

[0039] Figure 3A as well as Figure 3B Schematic diagram showing the difference in imaging direction due to angle when light is reflected an odd number of times inside the waveguide G. Figure 3A An example is shown in which the waveguide portion G is rotated to the side opposite to the user. Figure 3B An example is shown in which the waveguide portion G is rotated toward the user side. Figure 4A as well as Figure 4B Schematic diagram showing the difference in imaging direction due to angle when light is reflected an even number of times inside the waveguide G. Figure 4A An example is shown in which the waveguide portion G is rotated to the side opposite to the user. Figure 4B An example is shown in which the waveguide portion G is rotated toward the user side. Figure 4B In the figure, the line of sight direction when θ=0 degrees is indicated by a two-dot chain line.

[0040] exist Figure 3A 、 Figure 3B 、 Figure 4A as well as Figure 4BIn the figure, the dotted arrows indicate the path of the light emitted from the first image projection unit S when the waveguide unit G is rotated at an angle θ=0 degrees, which is equivalent to Figure 1 As shown by the solid arrow. Figure 3A 、 Figure 3B 、 Figure 4A as well as Figure 4B In FIG, the solid arrows indicate the paths of the light emitted from the first image projection unit S when each waveguide unit G rotates. Figure 1 Similarly, light incident on the reflective portion M from below in the figure propagates while being totally reflected on the inner surface of the waveguide portion G, and reaches the partial reflective portion HM. The light reflected by the partial reflective portion HM is projected toward the viewpoint. Figure 3A 、 Figure 3B 、 Figure 4A as well as Figure 4B As shown by the arrow drawn by the single-dot chain line in FIG, it appears as if the first image is displayed in the depth of the partial reflection part HM from the viewpoint. Figure 4B In the example shown, the direction of the first image visually confirmed is slightly changed in the lateral direction compared to the case of θ=0 degrees.

[0041] like Figure 3A 、 Figure 3B 、 Figure 4A as well as Figure 4B As shown, whether the light is reflected an odd number of times by the main surface of the waveguide portion G or an even number of times, the traveling angle of the light projected from the partial reflection portion HM can be made equal to Figure 1 Furthermore, regardless of whether the waveguide G is rotated toward the user or the opposite side to the user, light can be projected toward the user at an angle different from the line of sight H1.

[0042] (Example)

[0043] Figure 5 : is a photograph showing an embodiment of the image display device 100. The transparent plate-shaped member shown in the figure is the waveguide portion G, and the black frame shown on the right side of the waveguide portion G is the housing portion CS. The white solid line shown in the figure represents the inclination of the waveguide portion G when the rotation angle θ is changed from 0 degrees to 20 degrees with the rotation axis AX as the center. Figure 5 In the example shown, the waveguide portion G is located at θ=0 degrees.

[0044] Figure 6 Yes Figure 5 The photographs show how the display position of the first image changes when the rotation angle θ is changed in the embodiment shown. Figure 6The photograph shown is a magnified photograph of the vicinity of the partial reflector HM while visually confirming the line of sight direction H1 from the viewpoint. The white rectangle shown in the figure is the first image projected from the first image projector S, with a blank triangle added to the lower right corner of the first image.

[0045] like Figure 6 As shown, by rotating the waveguide portion G laterally about the rotation axis AX, the projection direction of the first image projected from the partial reflection portion HM changes, and the visual confirmation direction of the first image changes from the user's viewpoint.

[0046] As described above, in the image display device 100 of this embodiment, the waveguide portion G serving as the projection optical portion is held by the shell portion CS serving as the rotation holding portion so as to be rotatable laterally, thereby being able to change the projection position in the air of the first image irradiated from the first image projection portion S, thereby being able to increase the degree of freedom of the display position.

[0047] (Second embodiment)

[0048] Next, use Figures 7 to 9 A second embodiment of the present disclosure will be described, and descriptions of the contents overlapping with those of the first embodiment will be omitted. Figure 7 is a light path diagram of the image display device 110 of this embodiment. Figure 7 As shown, the image display device 110 includes a first image projecting unit S1, a first beam splitter BS1 (an example of a beam splitter), a second beam splitter BS2, a retro-reflective unit RR, a reflective unit M, and a dichroic mirror DM. Figure 7 In FIG, the lines indicated by the dotted line and the two-dot chain line schematically indicate the path of the light emitted from the first image projection unit S1.

[0049] exist Figure 7 In the image display device 100 shown, the user visually recognizes the first front image A1 and the first rear image R1 projected from the first image projection unit S1 from viewpoints in the depth direction at different distances. Figure 7 In the example, the direction in which the first front image A1 and the first rear image R1 are arranged is defined as the depth direction, the vertical direction perpendicular to the depth direction is defined as the horizontal direction, and the direction perpendicular to the depth direction and the horizontal direction is defined as the vertical direction. Figure 7 In the image, the depth direction is used to express left and right, while the horizontal and vertical directions are used to express Figure 7 The position relationship in the image can also be changed up, down, left, and right.

[0050] The first image projection unit S1 is a device that irradiates light that forms an image, projecting the image at a predetermined distance from the user's eyes (viewpoint). The first image projection unit S1 is positioned to the right of the second beam splitter BS2, described later, and irradiates light laterally onto one surface of the second beam splitter BS2 (the surface facing the first beam splitter BS1).

[0051] The configuration of the first image projection unit S1 is not limited; for example, it may be a liquid crystal display device equipped with a backlight, a self-luminous organic EL display device, or a projector device using a light source and a modulation element. The image projected by the first image projection unit S1 may be a still image or a moving image. Furthermore, the first image projection unit S1 may include optical components such as lenses.

[0052] The first beam splitter BS1 transmits a portion of the incident light and reflects a portion. A partially reflective plate with a film that adjusts reflectivity may also be used on the surface of the first beam splitter BS1. The first beam splitter BS1 is positioned at a 45-degree angle in both the lateral and depth directions. Furthermore, it is also tilted 45 degrees relative to the optical axis of the light emitted from the first image projection unit S1.

[0053] The second beam splitter BS2 transmits a portion of the incident light and reflects a portion. A partially reflective plate with a reflectivity-adjusting film formed on its surface can be used. The second beam splitter BS2 is tilted at 45 degrees in both the lateral and depth directions. Furthermore, it is also tilted 45 degrees relative to the optical axis of the light projected from the first image projection unit S1. Furthermore, the first beam splitter BS1 and the second beam splitter BS2 are arranged opposite each other, intersecting at a 90-degree angle.

[0054] Here, the transmittance and reflectance of light in the first beam splitter BS1 and the second beam splitter BS2 can be selected to achieve an arbitrary balance. For example, the transmittance of the first beam splitter BS1 and the reflectance of the second beam splitter BS2 are both 50% and 50%. Furthermore, in this embodiment, the first beam splitter BS1 and the second beam splitter BS2 are arranged at a 45-degree angle relative to the optical axis of the light emitted from the first image projection unit S1, and are arranged orthogonally to the first beam splitter BS1 and the second beam splitter BS2. However, the arrangement of the first beam splitter BS1 and the second beam splitter BS2 is not limited to this embodiment; appropriate angles can be used depending on the relationship between the direction of light emitted from the first image projection unit S1 and the position of the image.

[0055] The first beam splitter BS1 and the second beam splitter BS2 of the present embodiment are plate-shaped beam splitters, but may be cubic beam splitters formed by joining the inclined surfaces of two right-angle prisms to each other so as to sandwich a film for adjusting reflectivity.

[0056] The retroreflective unit RR is an optical component that reflects incident light in the direction of incidence. Alternatively, a structure in which the surface of a reflective film is covered with tiny glass beads or a structure using prisms may be used. The retroreflective unit RR is positioned to the right of the first beam splitter BS1. The retroreflective surface of the retroreflective unit RR is perpendicular to the horizontal direction.

[0057] The reflector M is an optical component that reflects incident light in a regular manner relative to the incident direction. For example, a reflector having a structure in which the surface of a plate-like component is mirror-finished can be used in the reflector M. The reflector M is arranged in the depth direction along with the first beam splitter BS1 and the second beam splitter BS2, and the reflective surface of the reflector M is orthogonal to the depth direction. Figure 7 In FIG, a flat plate-shaped reflecting portion M is shown, but a concave mirror or a convex mirror may also be used.

[0058] The dichroic mirror DM is an optical component that reflects light of a specific wavelength and transmits light of other wavelengths. The dichroic mirror DM is arranged to the left of the retro-reflective portion RR and the first beam splitter BS1 and can be tilted and rotated in the depth direction. Figure 7 In the example shown, the dichroic mirror DM reflects certain wavelengths of light projected from the first image projection unit S1, while transmitting other visible light. As will be described later, the light reflected by the dichroic mirror DM spatially forms a first front image A1 and a first rear image R1. Therefore, the dichroic mirror DM constitutes the projection optical unit in the present disclosure.

[0059] In addition, although Figure 7 Although omitted in the figure, an imaging lens may be disposed between the first beam splitter BS1 and the dichroic mirror DM as part of the imaging optical system. The imaging lens is an optical component used to image the light traveling from the first beam splitter BS1 at a predetermined spatial position. Alternatively, multiple lens groups may be used as the imaging lens.

[0060] like Figure 7 As shown, the light emitted from the first image projection unit S1 is reflected by the second beam splitter BS2 and then reaches the first beam splitter BS1. A portion of the light reaching the first beam splitter BS1 is reflected and travels toward the retro-reflection unit RR, and is reflected again by the retro-reflection unit RR and enters the first beam splitter BS1 again. Here, as shown in FIG. Figure 1 As shown, the light that has expanded its optical path before reaching the retro-reflective section RR is incident on the first beam splitter BS1 as light with a narrowed optical path due to the retro-reflective characteristics of the retro-reflective section RR. The light that has again entered the first beam splitter BS1 passes through the first beam splitter BS1, is reflected by the dichroic mirror DM, and is focused at a first distance between the dichroic mirror DM and the viewpoint, forming a first front image A1.

[0061] The remaining portion of the light that reaches the first beam splitter BS1 passes through and travels toward the reflector M, where it is reflected again and re-enters the first beam splitter BS1. The light that re-enters the first beam splitter BS1 is reflected by the first beam splitter BS1 and then by the dichroic mirror DM, traveling toward the viewpoint. At this point, the light reflected by the reflector M, the first beam splitter BS1, and the dichroic mirror DM has a widened optical path. Therefore, to the user, it appears as light focused at a second distance behind the dichroic mirror DM. Consequently, the first rear image R1 is formed behind the dichroic mirror DM.

[0062] Light formed as the first front image A1 and the first rear image R1 reaches the user's eyes. Thus, the user visually recognizes the first front image A1 and the first rear image R1 in the depth direction. Furthermore, if a transmissive plate that transmits background light is positioned in the direction of the user's viewpoint, the user can also visually recognize the background through the transmissive plate, and can also visually recognize the first front image A1 formed in front of the dichroic mirror DM and the first rear image R1 formed behind the dichroic mirror DM.

[0063] Specific examples of the transmissive panels include display surfaces of other head-mounted displays (HMDs), vehicle windshields, helmet visors, etc. These transmissive panels may also be used to display images using other display devices.

[0064] Here, in Figure 7 In FIG. 1 , an example is shown in which the second beam splitter BS2, the first beam splitter BS1, and the reflector M are arranged in the depth direction. However, even if the reflector M and the retro-reflector RR are replaced, the first front image A1 and the first rear image R1 are formed on the same plane as the image. Figure 1 In addition, the same position as shown in Figure 7 In the figure, the light from the first image projection unit S1 is reflected by the second beam splitter BS2 and reaches the first beam splitter BS1. However, the first image projection unit S1 can also be arranged in the depth direction of the second beam splitter BS2, and the light transmitted through the second beam splitter BS2 reaches the first beam splitter BS1. Alternatively, the second beam splitter BS2 can be omitted and the light can be directly incident on the first beam splitter BS1. Furthermore, another image projection unit can be provided so that the light is incident on the first beam splitter BS1 via the second beam splitter BS2, thereby forming multiple front and rear images.

[0065] Figure 8 1 is a schematic top view of the image display device 110. Figure 8As shown, the image display device 110 includes a first image projection unit S1, a first beam splitter BS1, a second beam splitter BS2, a retroreflective unit RR, a reflector M, a dichroic mirror DM, a shutter unit SH, a housing CS, and a rotation support unit ARM. The dichroic mirror DM is held by the housing CS about a rotation axis AX1, while the rotation support unit ARM is held about a rotation axis AX2. Therefore, the combination of the rotation support unit ARM and the housing CS includes the rotation axes AX1 and AX2, and corresponds to the rotation holding unit in the present disclosure.

[0066] The shutter unit SH is an optical component positioned between the first beam splitter BS1 and the retro-reflective unit RR, and between the first beam splitter BS1 and the reflective unit M, that switches between passing and blocking light. The specific configuration of the shutter unit SH is not limited; known components such as an optical isolator, a liquid crystal shutter, and an aperture may also be used. The switching of the shutter unit SH (passing and blocking) is controlled by a control unit (not shown).

[0067] The shell CS is a frame that houses and holds each part. Figure 8 In the example shown, the first beam splitter BS1, the second beam splitter BS2, the retroreflective unit RR, the reflective unit M, and the shutter unit SH are housed inside the housing CS, while the first image projection unit S1 and the dichroic mirror DM are held outside the housing CS.

[0068] The rotation support ARM is a component that supports the first beam splitter BS1, the retro-reflective unit RR, the reflective unit M, and the dichroic mirror DM while maintaining their relative positional relationship. It is also configured to rotate about the rotation axis AX2. In this embodiment, the first image projection unit S1 is also supported by the rotation support ARM.

[0069] The rotation support part ARM can rotate while maintaining the relative positional relationship of each part, so it needs to be made of a material with a certain degree of rigidity. The specific material and shape of the rotation support part ARM are not limited, but for example, metal, resin, paper, etc. can also be used.

[0070] In this embodiment, the path of light projected by the first image projection unit S1 is the same as in the first embodiment, forming a first front image A1 on the side of the dichroic mirror DM closer to the user, and forming a first rear image R1 on the side farther from the dichroic mirror DM. In this case, only light along the path through which the shutter unit SH is open (transmitted) forms an image, allowing the first front image A1 and the first rear image R1 to be selectively formed by opening and closing the shutter unit SH.

[0071] Specifically, if the shutter portion SH disposed between the first beam splitter BS1 and the retro-reflective portion RR is in a transmissive state, and the shutter portion SH disposed between the first beam splitter BS1 and the retro-reflective portion RR is in a blocking state, only the first front image A1 is formed. Conversely, if the shutter portion SH disposed between the first beam splitter BS1 and the retro-reflective portion RR is in a blocking state, and the shutter portion SH disposed between the first beam splitter BS1 and the retro-reflective portion RR is in a transmissive state, only the first rear image R1 is formed.

[0072] As described above, in the image display device 110 of this embodiment, the first front image A1 and the first rear image R1 can be selectively formed by opening and closing the shutter unit SH, thereby enabling the user to switch between displaying the first front image A1 and the first rear image R1. Furthermore, even if a transmissive plate that transmits background light is disposed in the direction of the user's viewpoint, the user can visually recognize the background through the transmissive plate, and can visually recognize the first front image A1 formed in front of the dichroic mirror DM and the first rear image R1 formed behind the dichroic mirror DM.

[0073] like Figure 8 As shown, the dichroic mirror DM is held within the housing CS so that one end thereof can be rotated laterally within an angle θ1 about a rotation axis AX1. The structure for rotatably holding the dichroic mirror DM within the housing CS is not particularly limited; for example, a structure in which a support shaft provided in the dichroic mirror DM is axially supported by a bearing provided in the housing CS may also be employed. Rotating the dichroic mirror DM about the rotation axis AX1 changes the angle of incidence of light incident on the surface of the dichroic mirror DM from the first beam splitter BS1, thereby changing the image positions of the first front image A1 and the first rear image R1. This allows the position of the first image projected from the first image projection unit S1 to be changed in the air, thereby increasing the degree of freedom in the display positions of the first front image A1 and the first rear image R1.

[0074] Here, the range of angle θ1 is preferably 25 degrees to the left and right of the user's viewpoint relative to the center of the front (-25°≤θ1≤25°). If the angle θ1 is greater than ±25°, the amount of eye movement required to visually confirm the spatial image of the first front image A1 and the first rear image R1 increases, making it difficult to maintain comfort when the image is displayed superimposed on the background.

[0075] Figure 9 1 is a schematic perspective view showing changes in imaging positions when the rotary support unit ARM is rotated in the image display device 110. Figure 9 In the figure, for simplicity and convenience, the first image projection unit S1, the first beam splitter BS1, the second beam splitter BS2, the retro-reflective unit RR, the reflecting unit M, the shutter unit SH and the housing CS are omitted.

[0076] like Figure 9 As shown, the rotation support unit ARM rotates around the rotation axis AX2, at least holding the dichroic mirror DM included in the projection optical unit, and can rotate in the left-right direction (lateral direction) within the angle range of θ2. Here, θ2 is the angle at which the rotation support unit ARM rotates in the left-right direction (lateral direction) with the direction directly in front of the horizontal direction visually confirmed by the user from the user's viewpoint e being 0 degrees. Hereinafter, θ2 being 0 degrees (the direction directly in front of the horizontal direction visually confirmed by the user) is referred to as the front center direction. Figure 9 In the figure, as the angle θ2, an example is shown in which the rotation support part ARM is rotated from the front center direction to the right direction, but it also includes the angle θ2. Figure 9 The opposite side is turned to the left.

[0077] By rotating the rotation support part ARM around the rotation axis AX2, Figure 7 The first beam splitter BS1, second beam splitter BS2, retroreflective unit RR, reflective unit M, and dichroic mirror DM are shown rotated by angle θ while maintaining their relative positional relationship. Consequently, the aerial image positions of the first front image A1 and first rear image R1 projected from the first image projection unit S1 are shifted by angle θ2, similar to the rotation of the rotary support unit ARM. This allows the user to visually view the aerial images of the first front image A1 and first rear image R1 in a direction displaced by angle θ from the front center.

[0078] Here, the range of angle θ2 is preferably within a range of 25 degrees to the left and right of the user's viewpoint e relative to the front center direction (-25°≤θ2≤25°). If the angle θ2 is greater than ±25°, the amount of eye movement required to visually confirm the spatial image of the first front image A1 and the first rear image R1 increases, making it difficult to maintain comfort when the image is displayed superimposed on the background.

[0079] Furthermore, in the rotating support unit ARM, it is preferred that the length from the rotation axis AX2 to the dichroic mirror DM is approximately the same as the length from the viewpoint e to the dichroic mirror DM. Furthermore, it is preferred that the rotation axis AX2 and the viewpoint e be at the same position in the depth direction. Consequently, the path of light reflected by the dichroic mirror DM and traveling in the direction of the viewpoint e shifts by the same amount as the rotation angle θ2 of the rotating support unit ARM. Consequently, the rotation of the rotating support unit ARM is linked to the shifting of the image positions of the first front image A1 and the first rear image R1, enabling intuitive changes in the image positions of the first front image A1 and the first rear image R1.

[0080] If the dichroic mirror DM is moved in parallel, the distance and relative angle of the dichroic mirror DM observed from the viewpoint e will change. In this case, the path of the light reflected by the dichroic mirror DM will be different from Figure 7 Unlike what is shown in , the display contents of the first front image A1 and the first rear image R1 are changed compared to before the change.

[0081] In contrast, in the image display device 110, the movement of the dichroic mirror DM is not parallel movement in the left-right direction, but rotational movement around the rotation axis AX2. As a result, the relative positional relationship and angular relationship of the projection optical portion for imaging the first front image A1 and the first rear image R1 are maintained. Figure 8 In the relationship shown, the imaging positions of the first front image A1 and the first rear image R1 are maintained at a distance from the viewpoint e, and the display content of the aerial image can be maintained regardless of the rotation of the rotary support ARM.

[0082] As described above, in the image display device 110 of this embodiment, the dichroic mirror DM, which is held by the rotation support unit ARM, can be rotated by an angle θ2 about the rotation axis AX2, and the dichroic mirror DM can be rotated by an angle θ1 about the rotation axis AX1. By providing the rotation support unit with multiple rotation axes, the positions of the first front image A1 and the first rear image R1 formed in space can be changed, thereby further increasing the degree of freedom in the display positions of the first front image A1 and the first rear image R1.

[0083] In addition, if Figure 9 As shown, by providing a head-mounted display (HMD) or the like in the direction of the central line of sight from viewpoint e, it is possible to simultaneously display the HMD and image the first front image A1 and the first rear image R1. In this case, by rotating the dichroic mirror DM about the rotation axis AX1 and the rotating support unit ARM about the rotation axis AX2, the image positions of the first front image A1 and the first rear image R1 can be shifted away from the display side of the HMD. This allows the HMD display to be separated from the display areas of the first front image A1 and the first rear image R1, making it easier to distinguish between them.

[0084] Alternatively, a filter can be incorporated into the dichroic mirror DM to block unwanted external light. A filter is an optical component that blocks ultraviolet light and / or infrared light, and a known film structure can also be used. The dichroic mirror DM and the filter can be constructed independently or integrated into a single piece. Alternatively, the dichroic mirror DM can reflect ultraviolet light and / or infrared light while also serving as a filter.

[0085] Therefore, even if ultraviolet light or infrared light travels from the outside toward viewpoint e, it is blocked or reflected by the filter, so it does not reach viewpoint e. This prevents ultraviolet light and infrared light from the outside from directly entering the user's viewpoint e, protecting the user's eyes.

[0086] (Third embodiment)

[0087] exist Figure 8 as well as Figure 9 In the second embodiment, an example in which the end of the rotation support portion ARM is the rotation axis AX2 is shown, but as Figure 8 As shown in FIG, the position where the rotation support portion ARM holds the housing portion CS may be set as the rotation axis AX2', so that the entire housing portion CS rotates around the rotation axis AX2' as the rotation center.

[0088] In this case, the viewing direction of the first image can be changed simply by rotating the housing CS about the rotation axis AX2'. Therefore, the movement amount of the housing CS and the dichroic mirror DM can be reduced compared to the case where the rotation axis AX2 is provided at the end of the rotation support ARM.

[0089] The present disclosure is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims. Embodiments obtained by appropriately combining technical means disclosed in different embodiments are also included in the technical scope of the present disclosure.

[0090] This application incorporates, as appropriate, the contents disclosed in Japanese Patent Application No. 2020-059210 filed on March 27, 2020.

Claims

1. An image display device, characterized in that: have: a first image projection unit that projects a first image; a projection optical unit configured to project the light of the first image toward a viewpoint; and a rotation holding portion that holds the projection optical portion so as to be rotatable laterally about a rotation axis so as to change an angle θ between a direction in which light of the first image projected from the projection optical portion travels and a central line of sight direction from the viewpoint; The projection optical unit includes a dichroic mirror that selectively reflects the wavelength of light emitted by the first image projection unit. The image display device comprises: a first beam splitter that reflects a portion of the light emitted by the first image projection unit in a first direction and transmits the remaining light in a second direction; a reflecting portion configured to reflect light traveling from the first beam splitter in one of the first direction and the second direction toward the first beam splitter; as well as a retro-reflective portion that reflects light traveling from the first beam splitter in the other of the first direction and the second direction toward the first beam splitter, The dichroic mirror forms a spatial image of the light reflected by the reflecting portion and the retro-reflecting portion.

2. The image display device according to claim 1, wherein The first image projection unit includes a laser light source unit that irradiates a laser beam.

3. The image display device according to claim 1 or 2, characterized in that The rotation range of the rotation holding portion is within a range from -25 degrees to +25 degrees of the angle θ.

4. The image display device according to claim 1 or 2, wherein: The rotation holding portion includes a plurality of rotation shafts.

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