Image projection device

Abstract

A HUD (42) displays a virtual image within an eye box (EB). The HUD (42) is provided with a first concave mirror (422) and a second concave mirror (424) which respectively emit light to a first region (R1) and a second region (R2) that are different from each other and are smaller than the maximum region of the eye box (EB).

Description

Image irradiation device

[0001] The present disclosure relates to an image projection device.

[0002] An image projection device for a vehicle is known, as disclosed in Patent Document 1. The image projection device projects an image or video onto a windshield or a combiner, and superimposes the image on real space through the windshield or the combiner so that the image is visually recognized by the occupant, thereby realizing so-called augmented reality (AR).

[0003] The image projection device disclosed in Patent Document 1 includes an illumination device, a polarization separation element, a first optical modulation unit, a second optical modulation unit, and a projection unit. The polarization separation element transmits a first polarized light and reflects a second polarized light orthogonal to the first polarized light from the illumination device. The first optical modulation unit displays a first image using the transmitted light that has passed through the polarization separation element. The second optical modulation unit displays a second image using the reflected light from the polarization separation element. The projection unit projects the first image onto a first projection area on a projection surface, and projects the second image onto a second projection area different from the first projection area on the projection surface.

[0004] Japanese Patent Application Publication No. 2018-072597

[0005] Since the line of sight of a vehicle occupant can move, the image projection device is configured to emit light within a range (eye box) in which the occupant can see a virtual image. The size of the reflector of the image projection device is determined by the angle of view of the occupant and the size of the eye box. Therefore, in order to emit light to the entire area of ​​the eye box, a large reflector is required, and there is room for improvement in miniaturizing the entire device.

[0006] An object of the present disclosure is to provide an image projection device that can easily reduce the size of the entire device.

[0007] An image projection device according to one aspect of the present disclosure is an image projection device that displays a virtual image within an eyebox, and includes a plurality of reflecting mirrors that emit light to different areas that are smaller than the maximum area of ​​the eyebox.

[0008] According to the present disclosure, an image projection device is provided that can easily reduce the size of the entire device.

[0009] Fig. 1 is a schematic diagram illustrating a vehicle 1 provided with an image projection device of the present disclosure. Fig. 2 is a perspective view of the image projection device of Fig. 1. Fig. 3 is a schematic diagram showing the relationship between an eye box and an illumination area of ​​light of the image projection device of Fig. 1.

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. For the sake of convenience, descriptions of components having the same reference numerals as those already described in the description of the embodiments will be omitted. Furthermore, for the sake of convenience, the dimensions of each component shown in the drawings may differ from the actual dimensions of each component.

[0011] Furthermore, in the description of this embodiment, for convenience of explanation, the terms "left-right direction," "up-down direction," and "front-rear direction" may be referred to as appropriate. These directions are relative directions set for the head-up display (HUD) 42 shown in FIG. 1 . Here, the "left-right direction" refers to a direction including the "left direction" and the "right direction." The "up-down direction" refers to a direction including the "upward direction" and the "downward direction." The "front-rear direction" refers to a direction including the "forward direction" and the "rearward direction." The front-rear direction in the HUD 42 and the front-rear direction in the vehicle 1 coincide with each other. Here, the traveling direction of the vehicle 1 is defined as the forward direction. Although not shown in FIG. 1 , the left-right direction refers to a direction perpendicular to the up-down direction and the front-rear direction. The left-right direction also corresponds to the width direction of the vehicle 1.

[0012] 1 is a schematic diagram illustrating a vehicle 1 equipped with a HUD 42 according to the present embodiment. As shown in FIG. 1, the vehicle 1 is equipped with the HUD 42 and a camera 62.

[0013] At least a portion of the HUD 42 is located inside the vehicle 1. Specifically, the HUD 42 is installed at a predetermined location inside the vehicle 1. For example, the HUD 42 may be disposed inside the dashboard of the vehicle 1. The HUD 42 is an example of an image projection device.

[0014] The HUD 42 is configured to display a virtual image. More specifically, the HUD 42 is configured to display predetermined information (hereinafter referred to as HUD information) as an image directed to the occupant of the vehicle 1 so that the HUD information is superimposed on the real space outside the vehicle 1 (particularly, the surrounding environment ahead of the vehicle 1). The HUD information displayed by the HUD 42 is, for example, vehicle driving information related to the driving of the vehicle 1 and / or surrounding environment information related to the surrounding environment of the vehicle 1 (particularly, information related to objects present outside the vehicle 1). The HUD 42 is an AR display that functions as a visual interface between the vehicle 1 and the occupant.

[0015] The camera 62 is disposed inside the vehicle 1 and configured to acquire image data showing the occupant. The camera 62 functions as a tracking camera that tracks the occupant's viewpoint E. The camera 62 may have a light projection function, an image processing function, and an arithmetic processing function required for tracking. Here, the occupant's viewpoint E is the viewpoint of the occupant's left eye and right eye. The camera 62 is connected to a vehicle control unit 22 that controls the driving of the vehicle 1. The vehicle control unit 22 may identify the position of the occupant's left eye and the position of the occupant's right eye based on the image data acquired by the camera 62. The positions of the occupant's left eye and right eye are updated at a predetermined interval based on the image data.

[0016] The camera 62 defines an eye box EB as a detectable area. The eye box EB is fixed depending on the position where the camera 62 is attached to the vehicle 1. The eye box EB has, for example, a rectangular shape. In this embodiment, the longitudinal direction of the eye box EB corresponds to the arrangement direction DA of the multiple concave mirrors described below. When the camera 62 detects the occupant's viewpoint E within the eye box EB, it transmits the eye box EB including the viewpoint E to the vehicle control unit 22 as image data. Based on the image data received from the camera 62, the vehicle control unit 22 may identify the position of the viewpoint E (the position of the occupant's left eye and the position of the occupant's right eye) as, for example, coordinates within the eye box EB.

[0017] The HUD 42 is configured to display a virtual image within this eye box EB. More specifically, light emitted from the HUD 42 is reflected by the windshield 18 of the vehicle 1 and irradiated onto the occupant's viewpoint E (the occupant's left eye and right eye). As a result, the occupant perceives the light emitted from the HUD 42 as an image (predetermined image) formed at a predetermined distance in front of the windshield 18. In this way, the image displayed by the HUD 42 is superimposed on the real space in front of the vehicle 1 through the windshield 18, allowing the occupant to visually perceive a virtual image object I formed by the predetermined image as floating above the road located outside the vehicle.

[0018] Next, the HUD 42 will be described in detail. Fig. 2 is a perspective view of the HUD 42. As shown in Fig. 2, the HUD 42 includes a picture generation unit (PGU) 420, a first concave mirror 422, a second concave mirror 424, a plane mirror 426, and a control unit 428. The first concave mirror 422 and the second concave mirror 424 are examples of a plurality of reflecting mirrors.

[0019] The image generating device 420 is configured to emit light that forms a predetermined image (virtual image) that is displayed toward the occupants of the vehicle 1. The image generating device 420 emits light that generates a changing image that changes depending on the situation of the vehicle 1, for example. The image generating device 420 has a light source, optical components, and a display device. The light source is, for example, a laser light source or an LED light source. The optical components include a prism, a lens, a diffuser, a magnifying glass, etc. The display device is, for example, a liquid crystal display, a DMD (Digital Mirror Device), etc.

[0020] The plane mirror 426 is disposed on the optical path of the light emitted from the image generating device 420. In this embodiment, the plane mirror 426 has a planar reflective surface. The reflective surface of the plane mirror 426 is disposed to face the emission surface of the image generating device 420. The plane mirror 426 reflects light at the same magnification as the image of the light emitted from the image generating device 420 and formed. The plane mirror 426 is configured to reflect a portion of the light emitted from the image generating device 420 toward the first concave mirror 422. Furthermore, the plane mirror 426 is configured to reflect another portion of the light emitted from the image generating device 420 toward the second concave mirror 424.

[0021] The first concave mirror 422 is disposed on the optical path of the light emitted from the image generating device 420. The first concave mirror 422 has a concavely curved reflective surface. The reflective surface of the first concave mirror 422 is disposed to face the reflective surface of the plane mirror 426. The first concave mirror 422 reflects the light at a predetermined magnification relative to the image of the light emitted from the image generating device 420 and formed. The first concave mirror 422 is configured to reflect the light emitted from the plane mirror 426 toward the windshield 18 ( FIG. 1 ). The light reflected by the first concave mirror 422 is irradiated toward the left eye of the occupant within the eye box EB.

[0022] The second concave mirror 424 is disposed on the optical path of the other light emitted from the image generating device 420. The second concave mirror 424 has a concavely curved reflective surface. The reflective surface of the second concave mirror 424 is disposed to face the reflective surface of the plane mirror 426. The second concave mirror 424 reflects the light at a predetermined magnification relative to the image of the light emitted from the image generating device 420 and formed. The second concave mirror 424 is configured to reflect the other light emitted from the plane mirror 426 toward the windshield 18 (FIG. 1). The light reflected by the second concave mirror 424 is irradiated toward the right eye of the occupant within the eye box EB.

[0023] The control unit 428 is configured to control the operation of each part of the HUD 42. The control unit 428 is connected to the vehicle control unit 22 that controls the driving of the vehicle 1 (FIG. 1). The control unit 428 can be realized by one or more processors and memories. Examples of the processor include a CPU, an MPU, and a GPU. Examples of the memory include a ROM and a RAM. In this case, the ROM is an example of a non-transitory computer-readable medium that stores a computer program that executes processing related to the operation of each part of the HUD 42. A general-purpose microprocessor specifies at least a portion of the computer program stored in the ROM, expands it on the RAM, and executes the above-mentioned processing in cooperation with the RAM.

[0024] The control unit 428 controls the operation of the image generation device 420. Specifically, the control unit 428 generates a control signal for controlling the operation of the image generation device 420 based on vehicle driving information, surrounding environment information, and the like transmitted from the vehicle control unit 22, and transmits the generated control signal to the image generation device 420. The vehicle driving information includes, for example, information related to the driving of the vehicle 1 (for example, vehicle speed, information related to autonomous driving, etc.). The surrounding environment information includes, for example, information related to objects present outside the vehicle 1 (pedestrians, other vehicles including a vehicle ahead, signs, etc.).

[0025] 3 is a schematic diagram showing the relationship between the eye box EB and the light irradiation area of ​​the HUD 42. In FIG. 3, the maximum area of ​​the eye box EB is indicated by a thick dashed line. As shown in FIG. 3, the first concave mirror 422 is configured to emit light to a first area R1 that is smaller than the maximum area of ​​the eye box EB. The second concave mirror 424 is configured to emit light to a second area R2 that is smaller than the maximum area of ​​the eye box EB. The first area R1 and the second area R2 are different areas.

[0026] More specifically, the first region R1 is a region that is displayed when the entire light-emitting surface of the emission surface of the image generating device 420 that emits light incident on the first concave mirror 422 is lit. Similarly, the second region R2 is a region that is displayed when the entire light-emitting surface of the emission surface of the image generating device 420 that emits light incident on the second concave mirror 424 is lit.

[0027] Unlike the present embodiment, if a single concave mirror were to illuminate the entire maximum area of ​​the eye box EB, a large concave mirror would be required. To accommodate such a single large, flat concave mirror within the HUD, a relatively large storage space would be required. However, according to the present embodiment, the first concave mirror 422 and the second concave mirror 424 each emit light toward a different area within the eye box EB, making it easier to make each concave mirror smaller. In other words, since the present embodiment divides a single large concave mirror into multiple small concave mirrors, it becomes easier to place small concave mirrors in storage space within the HUD 42 that was previously unused. In this way, since the HUD 42 is configured with the small first concave mirror 422 and the small second concave mirror 424, it is easier to miniaturize the entire HUD 42.

[0028] 3, the first concave mirror 422 may be configured so that the first region R1 is movable within a first movement range MR1. In other words, the maximum range over which the first region R1 can move is the first movement range MR1. Similarly, the second concave mirror 424 may be configured so that the second region R2 is movable within a second movement range MR2. In other words, the maximum range over which the second region R2 can move is the second movement range MR2. The first movement range MR1 and the second movement range MR2 are different movement ranges.

[0029] More specifically, the first concave mirror 422 is configured to rotate in a first direction D1 and a second direction D2 perpendicular to the first direction D1 ( FIG. 1 ). The first direction D1 is, for example, the up-down direction. The second direction D2 is, for example, the left-right direction. The first concave mirror 422 is supported by a first drive shaft A1 that rotates the first concave mirror 422 in the first direction D1 and a second drive shaft A2 that rotates the first concave mirror 422 in the second direction D2 ( FIG. 2 ). The first concave mirror 422 further includes a rotation mechanism that drives the first drive shaft A1 and the second drive shaft A2. The rotation mechanism is, for example, a swivel actuator. For example, the rotation mechanism rotates the first drive shaft A1 based on a control signal transmitted from the control unit 428. This causes the first concave mirror 422 to rotate in the up-down direction around the first drive shaft A1. Similarly, for example, the rotation mechanism rotates the second drive shaft A2 based on a control signal sent from the control unit 428. This causes the first concave mirror 422 to rotate left and right about the second drive shaft A2. Because the first concave mirror 422 is configured to rotate in the first direction D1 and the second direction D2 in this manner, the first region R1, which is the light irradiation range of the first concave mirror 422, can move within a first movement range MR1.

[0030] Similarly, the second concave mirror 424 is configured to rotate in the first direction D1 and the second direction D2 (FIGS. 1 and 2). The configuration of the second concave mirror 424 is similar to that of the first concave mirror 422, and therefore a description thereof will be omitted.

[0031] The control unit 428 may drive the first concave mirror 422 in at least one of the first direction D1 and the second direction D2 based on the position of the occupant's left eye acquired by the camera 62. Similarly, the control unit 428 may drive the second concave mirror 424 in at least one of the first direction D1 and the second direction D2 based on the position of the occupant's right eye acquired by the camera 62.

[0032] The control unit 428 may rotate the first concave mirror 422 and the second concave mirror 424 depending on the display position of the virtual image. The vehicle 1 is provided with an operation unit 82 that receives an operation by the occupant to display the display position of the virtual image ( FIG. 1 ). The operation unit 82 is, for example, a lever switch. If the occupant feels uncomfortable with the display position of the virtual image, the occupant can adjust the display position of the virtual image by moving the lever switch up, down, left, or right. The operation unit 82 is connected to the vehicle control unit 22. The vehicle control unit 22 may identify the display position of the virtual image to be changed based on the operation input of the occupant received by the operation unit 82 and transmit the identified position to the control unit 428 of the HUD 42.

[0033] The first concave mirror 422 and the second concave mirror 424 may be rotated independently of each other, or may be rotated in conjunction with each other.

[0034] In this way, the first region R1 and the second region R2 of the first concave mirror 422 and the second concave mirror 424 can move within different ranges. More specifically, the first concave mirror 422 and the second concave mirror 424 can rotate in the first direction D1 and the second direction D2, respectively, depending on the movement of the occupant's viewpoint E (left eye and right eye) and the display position of the virtual image. This effectively expands the area that can be illuminated by the first concave mirror 422 and the second concave mirror 424. This allows light to be irradiated over a wide area of ​​the eye box EB. Furthermore, using smaller first concave mirrors 422 and second concave mirrors 424 facilitates further miniaturization of the entire HUD 42.

[0035] The first movement range MR1 and the second movement range MR2 may partially overlap each other. In FIG. 3 , the area where the first movement range MR1 and the second movement range MR2 partially overlap each other is indicated by hatched areas. As shown in FIG. 3 , because the first movement range MR1 and the second movement range MR2 partially overlap each other, the HUD 42 of this embodiment can easily irradiate light over the entire maximum area of ​​the eyebox EB. In other words, the maximum area of ​​the eyebox EB, which would previously have been covered by a single large concave mirror in the past, can now be covered by multiple small concave mirrors (the first concave mirror 422 and the second concave mirror 424).

[0036] The size of the entire area from which the first concave mirror 422 and the second concave mirror 424 can emit light may be equal to or larger than the maximum area of ​​the eyebox EB. In FIG. 3 , the entire area from which the first concave mirror 422 and the second concave mirror 424 can emit light is the sum of the area of ​​the first movement range MR1 and the second movement range MR2, minus the area where the first movement range MR1 and the second movement range MR2 overlap (the shaded area). The size of this entire area is equal to or larger than the maximum area of ​​the eyebox EB, as indicated by the thick dashed line. As described above, according to this embodiment, the eyebox EB, which would conventionally be covered by a single large concave mirror, can be easily covered by multiple small concave mirrors (the first concave mirror 422 and the second concave mirror 424).

[0037] The light emitted from the first concave mirror 422 and the second concave mirror 424 may each form a single common virtual image. As shown in FIG. 3 , a first virtual image I1 is displayed in a first region R1 of the light emitted from the first concave mirror 422. The first virtual image I1 represents, for example, the traveling speed of the vehicle 1. Similarly, a second virtual image I2 is displayed in a second region R2 of the light emitted from the second concave mirror 424. Like the first virtual image I1, the second virtual image I2 also represents the traveling speed of the vehicle 1. In this way, the first concave mirror 422 and the second concave mirror 424 each form a single common virtual image, the first virtual image I1 and the second virtual image I2, so that the occupant can view a single virtual image.

[0038] Furthermore, the image generating device 420 may be arranged so that a portion of the image generating device 420 overlaps the first concave mirror 422 and the second concave mirror 424 when viewed from the array direction DA in which the first concave mirror 422 and the second concave mirror 424 are arranged ( FIG. 1 ). As shown in FIG. 1 , the lower end of the first concave mirror 422 is located below the lower end of the exit surface of the image generating device 420, and the upper end of the first concave mirror 422 is located above the upper end of the exit surface of the image generating device 420. The same applies to the positional relationship between the image generating device 420 and the second concave mirror 424. In this way, when viewed from the array direction DA, the image generating device 420 is arranged so that it overlaps the first concave mirror 422 and the second concave mirror 424 in the vertical direction. This allows for space savings compared to when the image generating device 420 is arranged farther away from the first concave mirror 422 or the second concave mirror 424 in the vertical direction.

[0039] Furthermore, the image generating device 420 may be provided between the first concave mirror 422 and the second concave mirror 424 in the array direction DA ( FIG. 2 ). In this embodiment, a single large concave mirror, which is conventional, is divided into multiple small concave mirrors (the first concave mirror 422 and the second concave mirror 424). This allows the image generating device 420 to be placed in a space that was not previously available, namely, between the first concave mirror 422 and the second concave mirror 424, thereby saving space.

[0040] Although the embodiments of the present disclosure have been described above, it goes without saying that the technical scope of the present disclosure should not be interpreted as being limited by the description of the present embodiments. The present embodiments are merely examples, and it will be understood by those skilled in the art that various modifications of the embodiments are possible within the scope of the invention described in the claims. The technical scope of the present disclosure should be determined based on the scope of the invention described in the claims and its equivalents.

[0041] The HUD 42 does not need to include the plane mirror 426. In this case, light emitted from the image generating device 420 can be directly irradiated onto the first concave mirror 422 and the second concave mirror 424. Even when the plane mirror 426 is not provided, the first concave mirror 422 and the second concave mirror 424 emit light to the first region R1 and the second region R2, respectively, which are smaller than the maximum region of the eye box EB. This provides the same effect as described above, that is, the entire HUD 42 can be easily miniaturized.

[0042] The HUD 42 may include multiple flat mirrors. One flat mirror may direct a portion of the light emitted from the image generating device 420 to the first concave mirror 422, and another flat mirror may direct another portion of the light emitted from the image generating device 420 to the second concave mirror 424.

[0043] The number of concave mirrors is not limited to two. For example, the number of concave mirrors may be four. In this case, the image generating device 420 may be arranged so as to be surrounded by four concave mirrors in the front-to-rear direction. Each concave mirror emits light to a different area that is smaller than the maximum area of ​​the eye box EB. Each of these four different areas may be movable within a corresponding range of movement, and the size of the total area into which all four concave mirrors can emit light may be equal to or larger than the maximum area of ​​the eye box EB.

[0044] The image generating device 420 does not have to be provided between the first concave mirror 422 and the second concave mirror 424. For example, in the array direction DA, the first concave mirror 422 may be provided between the second concave mirror 424 and the image generating device 420. It is sufficient that a portion of the light from the image generating device 420 is emitted toward the first concave mirror 422, and another portion of the light from the image generating device 420 is emitted toward the second concave mirror 424.

[0045] The first concave mirror 422 or the second concave mirror 424 may be configured to be driven in translation rather than rotation. For example, the first concave mirror 422 may be driven in translation in the front-to-rear direction.

[0046] The configurations described in the following items also constitute part of the present disclosure. Item 1: An image projection device that displays a virtual image in an eyebox, comprising a plurality of reflecting mirrors that emit light to different regions that are smaller than the maximum region of the eyebox. Item 2: The image projection device according to item 1, wherein the regions of the plurality of reflecting mirrors are configured to be movable within different movement ranges. Item 3: The image projection device according to item 2, wherein the movement ranges partially overlap each other. Item 4: The image projection device according to item 3, wherein the size of all regions from which all the plurality of reflecting mirrors can emit light is equal to or larger than the maximum region of the eyebox. Item 5: The image projection device according to any one of items 1 to 4, wherein light emitted by the plurality of reflecting mirrors each forms a single common virtual image. Item 6: The image projection device according to any one of items 1 to 5, wherein the plurality of reflecting mirrors are each concave mirrors. Item 7: The image projection device according to any one of Items 1 to 6, further comprising an image generation device that emits light that forms the virtual image, wherein at least a portion of the image generation device overlaps with the plurality of reflecting mirrors when viewed from an arrangement direction in which the plurality of reflecting mirrors are arranged. Item 8: The image projection device according to Item 7, wherein the image generation device is provided between the plurality of reflecting mirrors. Item 9: The image projection device according to any one of Items 1 to 8, wherein each of the plurality of reflecting mirrors rotates in a first direction and a second direction perpendicular to the first direction.

[0047] This application claims priority based on Japanese Application No. 2023-116022 filed on July 14, 2023, and incorporates by reference all of the contents of the aforementioned Japanese application.

Claims

1. An image projection device for displaying a virtual image within an eyebox, comprising a plurality of reflecting mirrors for emitting light to different areas each of which is smaller than the maximum area of ​​the eyebox.

2. The image projection device according to claim 1, wherein said plurality of reflecting mirrors are configured so that said regions are each movable within a different range of movement.

3. The image projection device according to claim 2, wherein the movement ranges overlap each other.

4. The image projection device according to claim 3, wherein the size of the entire area from which all of said plurality of reflecting mirrors can emit light is equal to or larger than said maximum area of ​​said eye box.

5. The image projection device of claim 1, wherein the light beams emitted by the plurality of reflecting mirrors each form a common virtual image.

6. The image projection device according to claim 1, wherein each of said plurality of reflecting mirrors is a concave mirror.

7. The image projection device according to claim 1, further comprising an image generating device that emits light that forms the virtual image, wherein at least a portion of the image generating device overlaps with the plurality of reflecting mirrors when viewed from the direction in which the plurality of reflecting mirrors are arranged.

8. The image projection device according to claim 7, wherein the image generating device is provided between the plurality of reflecting mirrors.

9. The image projection device according to claim 1, wherein each of the plurality of reflecting mirrors rotates in a first direction and in a second direction perpendicular to the first direction.

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