Image projection device

Abstract

To provide an image projection device with which it is possible to achieve both of projecting an image with a reduced movement of line of sight via a display unit and securing the visibility of high priority information, even when using polarizing sunglasses.SOLUTION: Provided is an image projection device (100) for projecting image light onto a display unit (WS) for displaying virtual images. The image projection device (100) comprises: an image irradiation unit (10) for irradiating first image light from a first image display region and irradiating second image light from a second image display region; and a projection optical system (20) for projecting the first image light and the second image light onto the display unit (WS). The first emission angle of the first image light and the second emission angle of the second image light from the image irradiation unit (10) are different.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an image projection device. [Background technology]

[0002] Conventionally, dashboards that light up icons have been used as devices for displaying various types of information inside a vehicle. As the amount of information to be displayed increases, it has been proposed to embed an image display device in the dashboard or to configure the entire dashboard with an image display device.

[0003] However, since the instrument panel is located below the windshield of the vehicle, in order for a driver or other passenger to view the information displayed on the instrument panel, the driver or other passenger must move his or her eyes downward while driving, which is undesirable. Therefore, image projection devices such as head up displays (hereinafter referred to as HUDs) have been proposed that project images onto the windshield so that passengers can read information when they view the area ahead of the vehicle (see, for example, Patent Documents 1 and 2).

[0004] In the image projection devices of Patent Documents 1 and 2, an image projection unit projects light containing an image, and the light is reflected by a free-form mirror or the like to reach the viewpoint of the passenger so that the image is formed in space via a display unit such as a windshield. This allows the passenger to perceive the image as being displayed at the imaging position in the depth direction by the light incident on the viewpoint. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2019-119248 A [Patent Document 2] JP 2019-119262 A Summary of the Invention [Problem to be solved by the invention]

[0006] In such conventional image projection devices, the reflectance of P-polarized light on the display unit, such as the windshield, is low, so the image light used to form a virtual image contains a large amount of S-polarized light. Therefore, when a driver, etc., wears polarized sunglasses, the S-polarized light of the image light reflected on the display unit is cut by the polarized sunglasses, making it difficult to see. In particular, when information such as meter display is included in the image light, this information has a high priority in driving operations, so wearing polarized sunglasses has a large impact on reduced visibility.

[0007] Therefore, the present invention has been made in consideration of the above-mentioned conventional problems, and aims to provide an image projection device that can achieve both virtual image projection with minimal eye movement via a display unit and ensure visibility of high-priority information even when using polarized sunglasses. [Means for solving the problem]

[0008] In order to solve the above problems, the image projection device of the present invention is an image projection device that projects image light onto a display unit for displaying a virtual image, and is equipped with an image irradiation unit that irradiates a first image light from a first image display area and a second image light from a second image display area, and a projection optical unit that projects the first image light and the second image light onto the display unit, and is characterized in that a first exit angle of the first image light from the image irradiation unit and a second exit angle of the second image light are different.

[0009] In such an image projection device of the present invention, the first exit angle of the first image light from the image irradiation unit and the second exit angle of the second image light are different, and the first image light and the second image light can be separated by different polarizations and projected by the projection optical unit onto the display unit, making it possible to achieve both virtual image projection with minimal eye movement via the display unit and ensuring visibility of high priority information even when using polarized sunglasses.

[0010] In one aspect of the invention, the display unit includes a mirror display unit that reflects the second image light toward a viewpoint, and the second emission angle is smaller than the first emission angle.

[0011] In one aspect of the invention, the mirror display section is disposed so as to be inclined at a predetermined angle in the width direction with respect to a path of the second image light toward the viewing direction.

[0012] In addition, in one aspect of the invention, the second image light is incident on the mirror display unit from a side opposite to the viewpoint of the mirror display unit.

[0013] In one aspect of the invention, the projection optical unit includes a reflecting mirror that reflects the second image light and makes it incident on the mirror display unit.

[0014] In one aspect of the invention, the display unit includes a transmissive screen that scatters and transmits at least a portion of the second image light.

[0015] In one aspect of the invention, the display unit includes a windshield provided on a vehicle, and the projection optical unit projects the first image light onto the windshield. Effect of the Invention

[0016] The present invention provides an image projection device that can achieve both virtual image projection with minimal line of sight movement via a display unit and ensure visibility of high-priority information even when using polarized sunglasses. [Brief description of the drawings]

[0017] [Figure 1] 1 is a schematic side cross-sectional view illustrating projection of a virtual image using the image projector 100 according to the first embodiment. [Diagram 2] 1 is a schematic top cross-sectional view illustrating projection of a virtual image using the image projection device 100. FIG. [Diagram 3]3A is a graph explaining the emission angles of image light for far distances and image light for near distances, and FIG. 3B is a schematic diagram explaining the arrangement of the far display area and the near display area in the image irradiation unit 10. [Figure 4] 11 is a schematic side cross-sectional view illustrating projection of a virtual image using an image projector 100 according to a second embodiment. FIG. [Diagram 5] FIG. 11 is a schematic side cross-sectional view illustrating projection of a virtual image using an image projector 100 according to a third embodiment. [Figure 6] 13 is a schematic side cross-sectional view illustrating projection of a virtual image using an image projector 100 according to a fourth embodiment. FIG. [Figure 7] 13 is a schematic diagram for explaining the display position and the imaging position of a virtual image when a transmissive screen 70 is not used. FIG. [Figure 8] 8A and 8B are diagrams for explaining a display using near image light, in which FIG. 8A shows a case in which a transmissive screen 70 is not used, and FIG. 8B shows a case in which a transmissive screen 70 is used. [Figure 9] 13 is a schematic side cross-sectional view illustrating projection of a virtual image using an image projector 100 according to a fifth embodiment. FIG. [Figure 10] 13 is a schematic side cross-sectional view illustrating projection of a virtual image using an image projector 100 according to a sixth embodiment. FIG. [Figure 11] 13 is a schematic side cross-sectional view illustrating projection of a virtual image using an image projector 100 according to a seventh embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] (First embodiment) Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing will be given the same reference numerals, and duplicated explanations will be omitted as appropriate. In the following explanation, an embodiment in which an image projection device 100 according to the present invention is applied to a HUD mounted on a vehicle or the like will be described as an example. FIG. 1 is a schematic side cross-sectional view explaining the projection of a virtual image using the image projection device 100 according to this embodiment.

[0019] As shown in Fig. 1, the image projection device 100 includes an image projection unit 10, a first mirror 20, a mirror display unit 30, a half-wave plate 40, and a housing 50. In the image projection device 100, each unit is controlled using a control unit (not shown) connected to each unit so as to be able to communicate information with the unit. The configuration of the control unit is not limited, but an example includes a CPU (Central Processing Unit) for performing information processing, a memory device, a recording medium, an information communication device, and the like. The control unit controls the operation of each unit according to a predetermined program, and sends information including an image (image information) to the image projection unit 10.

[0020] The image projection unit 10 is a part that projects light containing an image as image light onto the first mirror 20 based on image information from the control unit. The specific configuration of the image projection unit 10 is not limited, but as an example, the image projection unit 10 includes a light source, a lens, and an image display unit, and the light projection unit 10 adjusts the light distribution of the light projected from the light source and projects the image displayed on the image display unit as image light.

[0021] The image projection unit 10 has a single display area divided into a far display area and a near display area. The far image displayed in the far display area is reflected by the first mirror 20 and the windshield WS as far image light (first image light) and reaches the driver's viewpoint position e, as shown by the solid line in FIG. 1. The near image displayed in the near display area is transmitted through the half-wave plate 40 as near image light (second image light) and is reflected by the first mirror 20 and the mirror display unit 30 and reaches the driver's viewpoint position e, as shown by the solid line in FIG. In this embodiment, the far image light and near image light reflected by the windshield WS and the mirror display unit 30 reach the viewpoint position e, so that the combination of the windshield WS and the mirror display unit 30 corresponds to the display unit in the present invention.

[0022] Examples of distant images displayed in the distant display area include images that call attention to the driver's safety and emergency information, etc. Examples of near images displayed in the near display area include a speedometer, a volume indicator, a driving direction guide, etc.

[0023] The light sources are, for example, semiconductor light emitting elements such as LEDs (Light Emitting Diodes), and are arranged in a predetermined direction (the depth direction of the paper in FIG. 1). The light emission color of the light sources is not particularly limited, but in this embodiment, white light is used as an example. Note that, in this embodiment, the light sources are arranged in one row, but may be arranged in two or more rows. Furthermore, the light sources are not limited to LEDs, and may be semiconductor lasers, organic EL (Electro Luminescence) elements, etc.

[0024] A lens is an optical member that is arranged in the light emission direction of a plurality of light sources and has a function of adjusting the light distribution of the light emitted from the light sources and emitting, for example, parallel light or light close to parallel light (hereinafter, both of these will be collectively referred to as "approximately parallel light"). One example of a lens is a TIR (Total Internal Reflection) lens that has a refracting portion in the center that refracts light and reflecting portions on both sides of the refracting portion that reflect light.

[0025] The image display unit functions as a spatial light modulation unit in which light irradiated from a light source enters from the rear surface and emits light modulated by image information from the exit surface. The specific configuration of the image display unit is not limited, but as an example, a transmissive liquid crystal display device that transmits light incident from the rear surface and emits it from the front surface can be used. Since a transmissive liquid crystal display device transmits only light polarized in a specific direction, the device is arranged so that the polarization direction is S-polarized with respect to the windshield WS.

[0026] The first mirror 20 is an optical member that reflects the far-field image light and the near-field image light, which are among the image light arriving from the image projection unit 10, toward the windshield WS and the mirror display unit 30, respectively. In the example shown in Fig. 1, the first mirror 20 is shown as a concave reflecting mirror, but it is preferable to use a free-form surface mirror. Also, in Fig. 1, an example is shown in which the first mirror 20 is made up of a single mirror, but the image light may be irradiated onto the windshield WS and the mirror display unit 30 by repeatedly reflecting the light using multiple mirrors.

[0027] The reflecting surface of the first mirror 20 is designed to expand the light diameter in the driver's viewpoint direction in order to project the far-distance image light and the near-distance image light as virtual images through the windshield WS and the mirror display unit 30. Here, the expansion of the light diameter in the viewpoint direction includes not only the case where the light diameter expands consistently after reflection, but also the case where the light diameter shrinks and expands after forming an image at an intermediate point. The first mirror 20 corresponds to the projection optical unit in the present invention. In this embodiment, the near-distance image light reflected by the first mirror 20 reaches the mirror display unit 30, so the first mirror 20 corresponds to the reflecting mirror in the present invention.

[0028] The mirror display unit 30 is an optical member that irradiates image light that arrives from the near display area of ​​the first mirror 20 via the half-wave plate 40 in the direction of the viewpoint position e. Although Fig. 1 shows an example in which a concave mirror is used as the mirror display unit 30, a plane mirror or a convex mirror may also be used. Although Fig. 1 shows an example in which the mirror display unit 30 is placed above the dashboard and housed in a housing 50, the position and the presence or absence of a housing 50 are not limited.

[0029] The half-wave plate 40 is an optical member made of a birefringent material having different refractive indices in the slow axis and the fast axis. The half-wave plate 40 is designed so that a phase difference of half the wavelength of the light occurs between the slow axis and the fast axis before the incident light is emitted. The slow axis and the fast axis of the half-wave plate 40 are arranged in a direction that differs by 45 degrees from the polarization direction of the light irradiated from the near display area. Therefore, the second image light displayed in the near display area of ​​the image irradiation unit 10 and irradiated with S-polarized light is converted into P-polarized light after passing through the half-wave plate 40, reflected by the first mirror 20, and irradiated to the mirror display unit 30.

[0030] Furthermore, the half-wave plate 40 does not need to have a phase difference of exactly 50% with respect to the wavelength of light, and as long as it produces a phase difference close to 50%, it can perform the function of rotating the polarization direction in the plane. Since the angle of incidence on the half-wave plate 40 is not necessarily perpendicular, it is preferable to use a half-wave plate 40 with small angle dependency.

[0031] 1, the half-wave plate 40 is disposed so as to overlap the near display region of the image projection unit 10, but it may be disposed so as to overlap the far display region. In this case, the far image light and near image light emitted from the image display unit are P-polarized light with respect to the windshield WS, and the P-polarized far image light emitted from the far display region is converted to S-polarized light by the half-wave plate 40.

[0032] The housing 50 is formed of a light-shielding material, constitutes a part of the outer shape of the image projection device 100, and is a part that houses at least a part of each part that constitutes the image projection device 100. In the example shown in FIG. 1, the housing 50 is disposed so as to protrude above the dashboard of the vehicle, and the mirror display unit 30 is housed inside. Although not shown in the example shown in FIG. 1, the housing 50 is provided with a light exit port for transmitting the near image light irradiated from the mirror display unit 30. The light exit port may be an opening provided in the housing 50, or may be a region partially constituted by a light-transmitting material.

[0033] Although not shown in FIG. 1, the housing 50 may be provided with a warning light unit separate from the image projection unit 10. The warning light unit is a unit that displays information such as a warning light with the highest priority. The configuration of the warning light unit is not limited, and a liquid crystal display device may be used, or a backlight may be transmitted through an opening in a shade shaped like an icon. The position where the warning light unit is disposed is not limited.

[0034] The windshield WS is a part provided in front of the driver's seat of the vehicle that transmits visible light. On the inside surface of the vehicle, the windshield WS reflects the S-polarized distant image light incident from the image projection device 100 toward the viewpoint direction, and transmits light from outside the vehicle toward the viewpoint direction. Here, an example using the windshield WS is shown, but a combiner may be provided separately from the windshield WS to reflect the light from the image projection device 100 toward the viewpoint direction. In addition, the windshield WS is not limited to being located in front of the vehicle, and may be located to the side or rear as long as it projects an image toward the viewpoint of the passenger.

[0035] The virtual image is an image that is displayed as if it were formed in space on an extension of the path of the far-distance image light when the far-distance image light reflected by the windshield WS reaches the viewpoint (eyebox) of the passenger (not shown). The position where the virtual image is formed is determined by the composite focal length of the first mirror 20 and the windshield WS included in the image projection device 100.

[0036] In Fig. 1, the optical paths of the far-distance image light and the near-distance image light are drawn as a single straight line. However, the actual image light is displayed in a predetermined area in the image projection unit 10, and has a predetermined area in a direction perpendicular to the traveling direction. In Fig. 1, the S-polarized far-distance image light projected from the image projection unit 10 is shown by a solid line, and the near-distance image light converted to P-polarized light by the half-wave plate 40 is shown by a dashed line. The far-distance image light may be reflected by the first mirror 20 and travels with its light diameter reduced, and may be intermediately imaged at an intermediate image position F (not shown) between the first mirror 20 and the windshield WS.

[0037] As shown in Fig. 1, the S-polarized far-distance image light irradiated from the far-distance display area of ​​the image irradiating unit 10 is reflected by the first mirror 20 and the windshield WS and reaches the driver's viewpoint position e. The driver visually recognizes a virtual image formed on an extension of the optical path along which the far-distance image light is incident. In this embodiment, an example is shown in which the image projection device 100 projects the far-distance image light to form one virtual image, but the number of virtual images is not limited, and multiple virtual images may be formed at different depth positions.

[0038] The near distance image light irradiated from the near distance display area of ​​the image irradiating unit 10 is converted from S-polarized light to P-polarized light by the half-wave plate 40, and is reflected by the first mirror 20 and the mirror display unit 30 to reach the driver's viewpoint position e. The driver visually recognizes displays such as meters in the extension direction of the optical path along which the near distance image light has entered. The driver also visually recognizes warning displays displayed on the warning light unit.

[0039] At this time, the far-distance image light traveling from the windshield WS to the viewpoint position e is S-polarized light, and the near-distance image light traveling from the mirror display unit 30 to the viewpoint position e is P-polarized light. Therefore, even if the driver is wearing polarized sunglasses, the near image displayed by the P-polarized near-distance image light on the mirror display unit 30 can be clearly seen. Also, when the driver is not wearing polarized sunglasses, in addition to the near image displayed on the mirror display unit 30, the driver can view the S-polarized far-distance image light via the windshield WS by reducing the movement of the line of sight from the front.

[0040] Moreover, in the image projection device 100 of this embodiment, the first mirror 20 is disposed on the front side of the vehicle (closer to the windshield WS) than the mirror display unit 30. Therefore, the near image light is reflected by the first mirror 20 from the opposite side to the viewpoint position e and enters the mirror display unit 30. As a result, even if the irradiation direction of the far image light and the near image light from the image projection unit 10 is oriented horizontally, a path from the image projection unit 10 to the mirror display unit 30 can be secured, and the image projection device 100 can be made smaller and thinner.

[0041] FIG. 2 is a schematic top cross-sectional view illustrating the projection of a virtual image using the image projection device 100. The image projection device 100 mounted on a vehicle projects the far-field image light and the near-field image light from the traveling direction to the viewpoint position e of the driver, so it is usually disposed at a position offset from the center in the width direction of the windshield WS toward the driver's seat. Therefore, the area of ​​the windshield WS where the far-field image light is irradiated is inclined at a predetermined angle in the width direction with respect to the path of the far-field image light toward the viewpoint position e. Similarly, the mirror display unit 30 is preferably inclined at a predetermined angle in the width direction with respect to the path of the near-field image light toward the viewpoint position e, as shown by the dashed line in FIG. 2.

[0042] Fig. 3 is a diagram for explaining the far display area and the near display area of ​​the image projection unit 10, Fig. 3(a) is a graph for explaining the emission angle of the far image light and the near image light, and Fig. 3(b) is a schematic diagram for explaining the arrangement of the far display area and the near display area in the image projection unit 10. In Fig. 3(a), the horizontal axis indicates the emission angle of the light beam in the image projection unit 10, and the vertical axis indicates the contrast. In Fig. 3(a), the contrast required for the virtual image of the far image is indicated by a dashed line, and the contrast required for the meter display of the near image light is indicated by a broken line.

[0043] As shown in Fig. 3(a), the contrast of the image light irradiated from the image irradiating unit 10 is maximum in a direction perpendicular to the image display unit (emission angle 0 degrees), and the contrast decreases as the emission angle increases. The contrast of the image for far distances projected through the windshield WS may be lower than the contrast of the image light for near distances projected by the mirror display unit 30. Therefore, it is preferable that the first emission angle of the image light for far distances from the image irradiating unit 10 is different from the second emission angle of the image light for near distances, and the second emission angle is smaller than the first emission angle.

[0044] In FIG. 3(b), the far display area 10a in the image projection unit 10 is indicated by a thin broken line, and the near display area 10b is indicated by a dashed line. The angle between the long sides of the approximately rectangular far display area 10a and the near display area 10b is θ. As shown by the solid line in FIG. 2, when the mirror display unit 30 is disposed approximately perpendicular to the path of the near image light toward the viewpoint position e, the inclination angle in the width direction of the windshield WS is different. Therefore, it is necessary to correct the inclination of the far image light and the near image light reflected by the windshield WS and the mirror display unit 30 by providing the angle θ as shown in FIG. 3(b) in the image projection unit 10.

[0045] However, if the far display area 10a and the near display area 10b are inclined to each other by an angle θ as shown in Fig. 3(b), a large-area image display unit is required to display the far display area 10a and the near display area 10b, as shown by the thick dashed rectangle. Therefore, as shown by the dashed line in Fig. 2, the near image light is inclined by a predetermined angle in the width direction with respect to the path toward the viewpoint position e, thereby reducing the angle θ in Fig. 3(b). As a result, as shown by the thick solid rectangle in Fig. 3(b), the far display area 10a and the near display area 10b can be projected even with an image display unit with a small area, and the image projection device 100 can be made smaller.

[0046] As described above, in the image projection device 100 of this embodiment, the first emission angle of the image light for far distances from the image irradiation unit 10 and the second emission angle of the image light for near distances are different, and the image light for far distances and the image light for near distances can be separated by different polarizations and projected by the first mirror 20 onto the windshield WS and the mirror display unit 30, making it possible to achieve both virtual image projection with minimal eye movement via the windshield WS and ensuring visibility of high priority information even when using polarized sunglasses.

[0047] Second embodiment Next, a second embodiment of the present invention will be described with reference to FIG. 4. The description of the contents overlapping with the first embodiment will be omitted. FIG. 4 is a schematic side cross-sectional view for explaining the projection of a virtual image using the image projection device 100 according to this embodiment. As shown in FIG. 4, the image projection device 100 includes an image projection unit 10, a first mirror 21, a second mirror 22, a mirror display unit 30, a half-wave plate 40, and a housing 50. The first mirror 21 is an optical member that reflects the image light for distance arriving from the image projection unit 10 in the direction of the windshield WS. The second mirror 22 is an optical member that reflects the image light for near distance arriving from the image projection unit 10 in the direction of the mirror display unit 30.

[0048] In this embodiment, since the far-distance image light and the near-distance image light reflected by the windshield WS and the mirror display unit 30 reach the viewpoint position e, the combination of the windshield WS and the mirror display unit 30 corresponds to the display unit in the present invention. Also, in this embodiment, the combination of the first mirror 21 and the second mirror 22 corresponds to the projection optical unit in the present invention. Also, in this embodiment, since the near-distance image light reflected by the second mirror 22 reaches the mirror display unit 30, the second mirror 22 corresponds to the reflecting mirror in the present invention.

[0049] In the image projection device 100 of this embodiment, the S-polarized far-distance image light irradiated from the far-distance display area of ​​the image irradiating unit 10 is reflected by the first mirror 21 and the windshield WS to reach the driver's viewpoint position e. The driver visually recognizes a virtual image formed on an extension of the optical path along which the far-distance image light is incident. In addition, the near-distance image light irradiated from the near-distance display area of ​​the image irradiating unit 10 is converted from S-polarized light to P-polarized light by the half-wave plate 40, and is reflected by the second mirror 22 and the mirror display unit 30 to reach the driver's viewpoint position e. The driver visually recognizes displays such as meters in the extension direction of the optical path along which the near-distance image light is incident. In addition, the driver visually recognizes a warning display displayed on the warning light unit.

[0050] Also, in the image projection device 100 of this embodiment, the second mirror 22 is disposed on the front side of the vehicle (closer to the windshield WS) than the mirror display unit 30. Therefore, the near image light is reflected by the second mirror 22 from the opposite side of the viewpoint position e and enters the mirror display unit 30. As a result, even if the irradiation direction of the far image light and the near image light from the image projection unit 10 is directed horizontally, a path from the image projection unit 10 to the mirror display unit 30 can be secured, and the image projection device 100 can be made smaller and lower in height. In addition, since the far image light is reflected by the first mirror 21 and the near image light is reflected by the second mirror 22, the design freedom can be improved. In addition, by individually setting the inclination angles of the first mirror 21 and the second mirror 22, the depression angles for visually recognizing the far image light and the near image light can be individually set.

[0051] Third embodiment Next, a third embodiment of the present invention will be described with reference to FIG. 5. The description of the contents overlapping with the first embodiment will be omitted. FIG. 5 is a schematic side cross-sectional view for explaining the projection of a virtual image using the image projection device 100 according to this embodiment. As shown in FIG. 5, the image projection device 100 includes an image projection unit 10, a first mirror 21, a second mirror 22, a third mirror 23, a mirror display unit 30, a half-wave plate 40, and a housing 50. The third mirror 23 is an optical member that reflects the far-field image light and the near-field image light arriving from the image projection unit 10 toward the first mirror 21 and the second mirror 22, respectively.

[0052] In this embodiment, since the far-distance image light and the near-distance image light reflected by the windshield WS and the mirror display unit 30 reach the viewpoint position e, the combination of the windshield WS and the mirror display unit 30 corresponds to the display unit in the present invention. Also, in this embodiment, the combination of the first mirror 21, the second mirror 22, and the third mirror 23 corresponds to the projection optical unit in the present invention. Also, in this embodiment, since the near-distance image light reflected by the second mirror 22 reaches the mirror display unit 30, the second mirror 22 corresponds to the reflecting mirror in the present invention.

[0053] In the image projection device 100 of this embodiment, the S-polarized far-distance image light irradiated from the far-distance display area of ​​the image irradiating unit 10 is reflected by the third mirror 23, the first mirror 21, and the windshield WS to reach the driver's viewpoint position e. The driver visually recognizes a virtual image formed on an extension of the optical path along which the far-distance image light is incident. In addition, the near-distance image light irradiated from the near-distance display area of ​​the image irradiating unit 10 is converted from S-polarized light to P-polarized light by the half-wave plate 40, and is reflected by the third mirror 23, the second mirror 22, and the mirror display unit 30 to reach the driver's viewpoint position e. The driver visually recognizes the display of the meter, etc. in the extension direction of the optical path along which the near-distance image light is incident. In addition, the driver visually recognizes a warning display displayed on the warning light unit.

[0054] Also, in the image projection device 100 of this embodiment, the second mirror 22 is disposed further forward of the vehicle (closer to the windshield WS) than the mirror display unit 30. Therefore, the near image light is reflected by the second mirror 22 from the opposite side of the viewpoint position e and enters the mirror display unit 30. This ensures a path from the image irradiation unit 10 to the mirror display unit 30, and allows the image projection device 100 to be made smaller and thinner. In addition, since the far image light and the near image light are reflected by the third mirror 23, the angles of incidence to the first mirror 21 and the second mirror 22 can be made small, and aberration can be suppressed.

[0055] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described with reference to Figs. 6 to 8. The description of the contents overlapping with the first embodiment will be omitted. Fig. 6 is a schematic side cross-sectional view for explaining the projection of a virtual image using an image projection device 100 according to this embodiment. As shown in Fig. 6, the image projection device 100 includes an image irradiation unit 10, a first mirror 21, a second mirror 22, a prism 60, and a transmissive screen 70. The prism 60 is an optical member made of a material that transmits light, and changes the traveling direction of light by changing the incident angle and the exit angle of light. The transmissive screen 70 is a member that scatters and transmits at least a part of light.

[0056] In this embodiment, the far-distance image light reflected by the windshield WS and the near-distance image light transmitted through the transmissive screen 70 reach the viewpoint position e, and therefore the combination of the windshield WS and the transmissive screen 70 corresponds to the display unit in the present invention. Also, in this embodiment, the combination of the first mirror 21, the second mirror 22, and the prism 60 corresponds to the projection optical unit in the present invention.

[0057] In the image projection device 100 of this embodiment, the S-polarized far-distance image light irradiated from the far-distance display area of ​​the image irradiating unit 10 is reflected by the first mirror 21 and the windshield WS to reach the driver's viewpoint position e. The driver visually recognizes a virtual image formed on an extension of the optical path along which the far-distance image light is incident. The near-distance image light irradiated from the near-distance display area of ​​the image irradiating unit 10 is reflected by the second mirror 22, refracted by the prism 60, and transmitted through the transmissive screen 70 to reach the driver's viewpoint position e. The driver visually recognizes displays such as meters in the extension direction of the optical path along which the near-distance image light is incident. The driver also visually recognizes warning displays displayed on the warning light unit.

[0058] 7 is a schematic diagram for explaining the display position and the imaging position of the virtual image when the transmissive screen 70 is not used. The range in which the far-distance image light and the near-distance image light are visible at the driver's viewpoint position e is defined as the eye box, and the area in which the near-distance image light is reflected by the mirror display unit 30 is defined as the display position. As shown in FIG. 7, when the near-distance image light is projected by the mirror display unit 30 without using the transmissive screen 70, it is necessary to provide a margin around the display position so that the virtual image can be viewed from different positions in the eye box.

[0059] 8A and 8B are diagrams for explaining display using near image light, in which FIG. 8A shows a case where the transmissive screen 70 is not used, and FIG. 8B shows a case where the transmissive screen 70 is used. As shown in FIG. 8A, when the near image light is projected using the mirror display unit 30, a margin is required between the warning light unit and the housing 50, and the display size of the near image is reduced. As shown in FIG. 8B, when the near image light is projected using the transmissive screen 70, no margin is required between the warning light unit and the housing 50, and the entire area of ​​the transmissive screen 70 is effectively used to increase the display size of the near image, thereby improving visibility.

[0060] In addition, in the image projection device 100 of this embodiment, the transmission screen 70 is used to project the near image light, and therefore the near image light irradiated from the back surface of the transmission screen 70 and transmitted therethrough is made unpolarized by scattering. Therefore, even if the driver is wearing polarized sunglasses, the near image displayed by the unpolarized near image light displayed on the transmission screen 70 can be clearly seen.

[0061] Also, in the image projection device 100 of this embodiment, the second mirror 22 is disposed on the front side of the vehicle (closer to the windshield WS) than the transmissive screen 70. Therefore, the near image light is reflected by the second mirror 22 from the opposite side of the viewpoint position e and enters the transmissive screen 70. This ensures a path from the image irradiation unit 10 to the transmissive screen 70, and the image projection device 100 can be made smaller and thinner. Furthermore, by projecting the near image light using the transmissive screen 70, no margin is required between the warning light unit and the housing 50, and the entire area of ​​the transmissive screen 70 can be effectively used to increase the display size of the near image, thereby improving visibility.

[0062] Fifth embodiment Next, a fifth embodiment of the present invention will be described with reference to FIG. 9. The description of the contents overlapping with the first embodiment will be omitted. FIG. 9 is a schematic side cross-sectional view for explaining the projection of a virtual image using an image projection device 100 according to this embodiment. As shown in FIG. 9, the image projection device 100 includes an image irradiation unit 10, a first mirror 21, a half-wave plate 40, a prism 60, a transmission screen 70, a polarizing reflector 80, and a lens 81. The polarizing reflector 80 is an optical member that reflects polarized light in a predetermined direction and transmits and splits polarized light orthogonal to the predetermined direction. In the example shown in FIG. 9, the polarizing reflector 80 is arranged in a direction that reflects P polarized light toward the windshield WS and transmits S polarized light. The lens 81 is an optical member that refracts light to focus or expand it.

[0063] In this embodiment, the far-distance image light reflected by the windshield WS and the near-distance image light transmitted through the transmissive screen 70 reach the viewpoint position e, and therefore the combination of the windshield WS and the transmissive screen 70 corresponds to the display unit in the present invention. Also, in this embodiment, the combination of the first mirror 21, the polarizing reflector 80, the lens 81 and the prism 60 corresponds to the projection optical unit in the present invention.

[0064] In the image projection device 100 of this embodiment, the S-polarized far-distance image light irradiated from the far-distance display area of ​​the image irradiating unit 10 is reflected by the polarized reflecting unit 80, the first mirror 21, and the windshield WS to reach the driver's viewpoint position e. The driver visually recognizes a virtual image formed on an extension of the optical path along which the far-distance image light is incident. In addition, the S-polarized near-distance image light irradiated from the near-distance display area of ​​the image irradiating unit 10 is converted to P-polarized light by the half-wave plate 40, passes through the polarized reflecting unit 80 and the lens 81, is refracted by the prism 60, passes through the transmissive screen 70, and reaches the driver's viewpoint position e. The driver visually recognizes the display of the meter, etc. in the extension direction of the optical path along which the near-distance image light is incident. In addition, the driver visually recognizes a warning display displayed on the warning light unit.

[0065] In the image projection device 100 of this embodiment, the transmission screen 70 is also used to project the near image light, so that the near image light irradiated from the back of the transmission screen 70 and transmitted therethrough is made unpolarized by scattering. Therefore, even if the driver is wearing polarized sunglasses, the near image displayed by the unpolarized near image light displayed on the transmission screen 70 can be clearly seen. In addition, by reflecting the far image light by the polarized reflection unit 80 and making it incident on the first mirror 21, the image projection device 100 can be made compact while ensuring the optical path length.

[0066] Sixth embodiment Next, a sixth embodiment of the present invention will be described with reference to FIG. 10. The description of the contents overlapping with the first embodiment will be omitted. FIG. 10 is a schematic side cross-sectional view for explaining the projection of a virtual image using an image projection device 100 according to this embodiment. As shown in FIG. 10, the image projection device 100 includes an image irradiation unit 10, a first mirror 21, a second mirror 22, a transmissive screen 70, a fourth mirror 71, and a lens unit 90. The lens unit 90 is a combination of a plurality of lenses, and is an optical member that refracts light to focus or expand it. The fourth mirror 71 is an optical member that reflects the near image light that has passed through the transmissive screen 70 toward the driver's viewpoint position e.

[0067] In this embodiment, the far-distance image light reflected by the windshield WS and the near-distance image light transmitted through the transmissive screen 70 reach the viewpoint position e, and therefore the combination of the windshield WS and the transmissive screen 70 corresponds to the display unit in the present invention. Also, in this embodiment, the combination of the first mirror 21, the second mirror 22, the lens unit 90 and the fourth mirror 71 corresponds to the projection optical unit in the present invention.

[0068] In the image projection device 100 of this embodiment, the S-polarized far-distance image light irradiated from the far-distance display area of ​​the image irradiating unit 10 is reflected by the first mirror 21 and the windshield WS to reach the viewpoint position e of the driver. The driver visually recognizes a virtual image formed on an extension of the optical path along which the far-distance image light is incident. In addition, the near-distance image light irradiated from the near-distance display area of ​​the image irradiating unit 10 passes through the lens unit 90, is reflected by the second mirror 22, passes through the transmissive screen 70, is reflected by the fourth mirror 71, and reaches the viewpoint position e of the driver. The driver visually recognizes a virtual image of a meter or the like in the extension direction of the optical path along which the near-distance image light is incident. In addition, the driver visually recognizes a warning display displayed on the warning light unit.

[0069] In the image projection device 100 of this embodiment, the transmission screen 70 is also used to project the near image light, so that the near image light irradiated from the rear surface of the transmission screen 70 and transmitted therethrough is made unpolarized by scattering. Therefore, even if the driver is wearing polarized sunglasses, the near image displayed on the transmission screen 70 by the unpolarized near image light can be clearly seen.

[0070] Seventh embodiment Next, a seventh embodiment of the present invention will be described with reference to FIG. 11. Description of the contents overlapping with the first embodiment will be omitted. FIG. 11 is a schematic side cross-sectional view for explaining the projection of a virtual image using an image projection device 100 according to this embodiment. As shown in FIG. 11, the image projection device 100 includes an image irradiation unit 10, a first mirror 21, a fifth mirror 24, a sixth mirror 25, a seventh mirror 26, an eighth mirror 27, and a transmissive screen 70.

[0071] The fifth mirror 24 is an optical member that reflects the near image light from the image irradiation unit 10. The sixth mirror 25 is an optical member that reflects the near image light reflected by the fifth mirror 24 and the seventh mirror 26. The seventh mirror 26 is an optical member that reflects the near image light reflected by the sixth mirror 25 again to a different area of ​​the sixth mirror 25. The eighth mirror 27 is an optical member that reflects the near image light reflected by the sixth mirror 25 toward the transmission screen 70. The combination of the fifth mirror 24, the sixth mirror 25, and the seventh mirror 26 constitutes an Offner optical system.

[0072] In this embodiment, the far-distance image light reflected by the windshield WS and the near-distance image light transmitted through the transmissive screen 70 reach the viewpoint position e, and therefore the combination of the windshield WS and the transmissive screen 70 corresponds to the display unit in this invention. Also, in this embodiment, the combination of the first mirror 21, the fifth mirror 24, the sixth mirror 25, the seventh mirror 26 and the eighth mirror 27 corresponds to the projection optical unit in this invention.

[0073] In the image projection device 100 of this embodiment, the S-polarized far-distance image light irradiated from the far-distance display area of ​​the image irradiating unit 10 is reflected by the first mirror 21 and the windshield WS to reach the viewpoint position e of the driver. The driver visually recognizes a virtual image formed on an extension of the optical path along which the far-distance image light is incident. The near-distance image light irradiated from the near-distance display area of ​​the image irradiating unit 10 is reflected by the fifth mirror 24, the sixth mirror 25, the seventh mirror 26, the sixth mirror 25, and the eighth mirror 27 in this order, and passes through the transmissive screen 70 to reach the viewpoint position e of the driver. The driver visually recognizes a virtual image of a meter or the like in the extension direction of the optical path along which the near-distance image light is incident. The driver also visually recognizes a warning display displayed on the warning light unit.

[0074] In the image projection device 100 of this embodiment, the transmission screen 70 is also used to project the near image light, so that the near image light irradiated from the back surface of the transmission screen 70 and transmitted therethrough is made unpolarized by scattering. Therefore, even if the driver is wearing polarized sunglasses, the near image displayed by the unpolarized near image light displayed on the transmission screen 70 can be clearly seen. In addition, since an Offner optical system combining the fifth mirror 24, the sixth mirror 25, and the seventh mirror 26 is used as the projection optical unit, chromatic aberration can be suppressed to improve visibility.

[0075] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Explanation of symbols]

[0076] 100...Image projection device 10...Image irradiation unit 10a…Far display area 10b…Near display area 20,21…1st mirror 22…Second mirror 23…3rd mirror 24…5th mirror 25…6th mirror 26…7th mirror 27…8th mirror 30…Mirror display section 40...Half-wave plate 50…Housing 60…Prism 70...Transparent screen 71…4th mirror 80...Polarizing reflector 81...Lens 90…Lens section

Claims

1. An image projection device that projects image light onto a display unit for displaying a virtual image, an image irradiating unit that irradiates a first image light from a first image display region and that irradiates a second image light from a second image display region; a projection optical unit that projects the first image light and the second image light onto the display unit, An image projection device, wherein a first exit angle of the first image light from the image irradiation unit is different from a second exit angle of the second image light.

2. 2. The image projection device according to claim 1, the display unit includes a mirror display unit that reflects the second image light toward a viewpoint, The image projection device, wherein the second exit angle is smaller than the first exit angle.

3. 3. The image projection device according to claim 2, The image projection device, characterized in that the mirror display unit is disposed so as to be inclined at a predetermined angle in a width direction with respect to a path of the second image light toward the viewpoint direction.

4. 3. The image projection device according to claim 2, An image projection device, characterized in that the second image light is incident on the mirror display unit from the side opposite to the viewpoint of the mirror display unit.

5. 5. The image projection device according to claim 4, The image projection device according to claim 1, wherein the projection optical unit has a reflecting mirror that reflects the second image light and makes it incident on the mirror display unit.

6. 2. The image projection device according to claim 1, The image projection device according to claim 1, wherein the display unit includes a translucent screen that scatters and transmits at least a portion of the second image light.

7. 7. The image projection device according to claim 1, The display unit includes a windshield provided in a vehicle, The image projection device, wherein the projection optical unit projects the first image light onto the windshield.

Images