Image Projection Device

Abstract

To provide an image projection device with which it is possible to suppress a rise of temperature in an image irradiation unit due to external light.SOLUTION: Provided is an image projection device for irradiating a display unit with a projection image that displays a virtual image. The image projection device comprises: an image irradiation unit (20) for irradiating image light; a projection optical unit (40) for irradiating image light in a viewpoint direction as a projection image via the display unit; and a shutter unit (30) for switching between a transparent mode in which light is passed through and a cutoff mode in which light is cut off, and disposed on the optical path of image light somewhere from the image irradiation unit (20) to the display unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image projection device, and more particularly to an image projection device that projects a projection image onto a display unit for displaying a virtual image. [Background technology]

[0002] Conventionally, dashboards that illuminate icons have been used to display various types of information inside vehicles. 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 vehicle's windshield, the driver must move their eyes downward while driving in order to see the information displayed on the instrument panel, which is undesirable. Therefore, a head-up display (hereinafter referred to as HUD) has been proposed, which projects an image onto the windshield so that the driver can read information when looking ahead of the vehicle (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-119248 [Patent Document 2] Japanese Patent Application Publication No. 2019-119262 Summary of the Invention [Problem to be solved by the invention]

[0005] In such conventional HUD devices, a projection image is projected through the windshield, which serves as the display unit, and light is emitted from below the windshield upward. Therefore, when external light such as sunlight enters from above the windshield, the external light reaches the image projection unit that displays the image via the projection optical system. In this case, the external light that reaches the image projection unit via the projection optical system is concentrated by the optical power of the projection optical system, causing a problem of deterioration due to temperature rise.

[0006] To suppress this temperature rise, it has been proposed to place a wavelength cut filter in the optical path of the projection optical system to cut out the infrared and ultraviolet light contained in the external light. However, it is unavoidable that visible light contained in the external light passes through the wavelength cut filter and reaches the display unit, and because the light transmittance of the wavelength cut filter is not 100%, some of the light emitted from the display unit is also attenuated, which can cause a decrease in brightness of the image projection.

[0007] SUMMARY OF THE INVENTION The present invention has been made in consideration of the above-mentioned conventional problems, and has as its object to provide an image projection device capable of suppressing a temperature rise in the image irradiation section due to external light. [Means for solving the problem]

[0008] In order to solve the above-described problems, the image projection device of the present invention is an image projection device that projects a projection image onto a display unit for displaying a virtual image, and includes: an image projection unit that projects image light; a projection optical unit that projects the image light as the projection image in a viewing direction via the display unit; and a shutter unit that is disposed on an optical path of the image light between the image projection unit and the display unit and that switches between a transmission mode in which light is transmitted and a blocking mode in which light is blocked. The image projection unit includes a first projection area that projects a first image and a second projection area that projects a second image at different positions within the entire display area, the projection optical unit includes a first optical unit that projects the first image onto the display unit and a second optical unit that projects the second image onto the display unit, and the shutter unit selects the transmission mode and the blocking mode for each of the first projection area and the second projection area. It is characterized by:

[0009] In the image projection device of the present invention, the shutter section switches between transmitting and blocking light, so that it is possible to appropriately select between a transmission mode in which image light from the image irradiation section is transmitted to project an image, and a blocking mode in which external light is blocked to suppress a rise in temperature in the image irradiation section, thereby making it possible to suppress a rise in temperature in the image irradiation section due to external light.

[0010] In one aspect of the present invention, the image irradiation unit The shutter unit includes a first light-transmitting unit, a light-transmitting unit, a rotating body having a light-shielding unit, and a driving unit that drives the rotating body to rotate, the first light-transmitting unit being provided at a position overlapping the first irradiation area, and the second light-transmitting unit being provided at a position overlapping the second irradiation area. .

[0011] In another aspect of the present invention, The shutter portion has a disk shape, and the first light transmitting portion and the second light transmitting portion are formed in a fan shape along the circumferential direction of the disk shape. .

[0012] Also, In order to solve the above problem, the image projection device of the present invention is an image projection device that irradiates a projection image onto a display unit for displaying a virtual image, and includes an image irradiation unit that irradiates image light, a projection optical unit that irradiates the image light in the viewing direction via the display unit as the projection image, and a shutter unit that is arranged on the optical path of the image light between the image irradiation unit and the display unit and switches between a transmission mode that transmits light and a blocking mode that blocks light, wherein the projection optical unit images the image light at an intermediate imaging position on the optical path, and the shutter unit is arranged at the intermediate imaging position.

[0013] In another aspect of the present invention, The shutter unit includes a cylindrical rotating body having a light-transmitting portion and a light-blocking portion, and a driving portion that drives the rotating body to rotate. .

[0014] In another aspect of the present invention, The image irradiation unit irradiates the image light by pulse driving that repeatedly turns on and off, and the shutter unit selects the transmission mode during the light-on period of the pulse driving and the blocking mode during the light-off period of the pulse driving. [Effects of the Invention]

[0015] The present invention can provide an image projection device that can suppress a temperature rise in the image irradiation unit due to external light. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a block diagram showing a configuration of an image projection device 100 according to a first embodiment of the present invention. [Figure 2] 1 is a schematic cross-sectional view showing an example of the configuration of an image projection device 100 according to a first embodiment. [Figure 3] 2 is a schematic plan view showing an example of a shutter section 30 according to the first embodiment. FIG. [Figure 4]4A and 4B are schematic diagrams illustrating the transmission mode and blocking mode of the shutter unit 30, where FIG. 4A shows the display area in the image projection unit 20, FIG. 4B shows the transmission mode, and FIG. 4C shows the blocking mode. [Figure 5] 5A and 5B are timing charts according to a modification of the first embodiment, in which FIG. 5A shows the opening and closing timing of the shutter unit 30, and FIG. 5B shows the turning on and off of the light source unit 10. FIG. [Figure 6] 6A and 6B are schematic diagrams showing the relationship between the configuration of the shutter section 30 and the image irradiation section 20 in the second embodiment, where FIG. 6A shows the full transmission mode, FIG. 6B shows the far blocking mode, FIG. 6C shows the full blocking mode, and FIG. 6D shows the near blocking mode. [Figure 7] 7A and 7B are diagrams showing an example of the configuration of an image projection device 100 according to a third embodiment, where FIG. 7A is a schematic cross-sectional view of the entire device, and FIG. 7B is a schematic perspective view showing an example of a shutter unit 30. [Figure 8] 8A and 8B are schematic diagrams showing examples of the configuration of the shutter section 30 according to the fourth embodiment, where FIG. 8A shows an example of a substantially rectangular configuration, and FIG. 8B shows an example of a configuration in which a blocking mode is provided only in a partial area. DETAILED DESCRIPTION OF THE INVENTION

[0017] (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 assigned the same reference numerals, and redundant explanations will be omitted where appropriate. FIG. 1 is a block diagram showing the configuration of an image projection device 100 according to this embodiment. As shown in FIG. 1, the image projection device 100 includes a light source unit 10, an image projection unit 20, a shutter unit 30, a projection optical unit 40, and a control unit 50. Light projected from the image projection device 100 is irradiated onto the driver's viewpoint via a windshield (display unit) not shown.

[0018] The light source unit 10 is a light source that irradiates light onto the image irradiation unit 20. The light emitted from the light source unit 10 may be a constant light emission, but is preferably PWM (Pulse Width Modulation) controlled in accordance with a control signal from the control unit 50, as will be described later. The specific configuration of the light source unit 10 is not limited, but a light emitting diode (LED), an organic EL element, or the like can be used.

[0019] The image projection unit 20 is a part that projects light containing an image (image light) based on image information from the control unit 50. The specific configuration of the image projection unit 20 is not limited, and a conventionally known device such as a liquid crystal display device, an organic EL display device, or a combination of a laser light source and a light modulation element can be used. In the example shown in FIG. 1, a device that projects light from a light source unit 10 from the rear side of the liquid crystal display device is used. As will be described later, the image projection unit 20 may be configured to include a near display region 22 and a far display region 23 that display a near image and a far image, respectively.

[0020] The shutter unit 30 switches between a transmission mode that transmits light and a blocking mode that blocks light in response to a control signal from the control unit 50. The configuration of the shutter unit 30 is not limited, but examples include a liquid crystal shutter that can change light transmittance in response to an electrical signal, a digital mirror device that switches the direction of light reflection, and a mechanical shutter that mechanically switches between an opening and a blocking section. When a mechanical shutter is used as the shutter unit 30, the shutter unit 30 may be provided with a mechanism and a drive unit that operate the light blocking plate of the shutter unit 30. Because the shutter unit 30 has a light blocking section that blocks external light, the temperature of the shutter unit 30 itself is likely to rise due to the blocked external light. Therefore, it is preferable that the shutter unit 30 be made of a metal material with high thermal conductivity.

[0021] The projection optical unit 40 is an optical member for irradiating the image light from the image projection unit 20 onto the windshield, which is the display unit. The projection optical unit 40 may include multiple optical members, or may be a combination of multiple lenses, concave mirrors, convex mirrors, prisms, etc. Furthermore, the image light from the image projection unit 20 may be focused at the same distance along a single optical path, or may be branched into multiple optical paths to focus images at multiple focal lengths.

[0022] The control unit 50 is a part that is connected to each part so as to be able to communicate information with each part and controls each part. The configuration of the control unit 50 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, etc. The control unit 50 controls the operation of each part in accordance with a predetermined program, and sends information including an image (image information) to the image projection unit 20.

[0023] Fig. 2 is a schematic cross-sectional view showing an example of the configuration of an image projection device 100 according to this embodiment. In the example shown in Fig. 2, a transmissive liquid crystal display device is arranged as an image projection unit 20 on the light irradiation surface of a light source unit 10 having an LED, and a shutter unit 30 is arranged opposite the light emission surface of the image projection unit 20. A specific example of the configuration of the shutter unit 30 will be described later. In addition, in the example shown in Fig. 2, a light branching unit 41, a free-form surface mirror 42, a reflecting mirror 43, and a free-form surface mirror 44 are provided as a projection optical unit 40.

[0024] The light branching unit 41 is an optical element that branches the image light emitted from the image projection unit 20, and branches at least the first image displayed in the far display region 23 as first image light L1 and the second image displayed in the near display region 22 as second image light L2. The shutter unit 30 is disposed between the light branching unit 41 and the image projection unit 20. The structure of the light branching unit 41 is not limited as long as it is an optical element that branches light, and a prism may be used, or a method such as using a reflecting mirror to change the angle of incidence and the angle of reflection of light may be used. In the example shown in FIG. 2, a prism is used as the light branching unit 41, and the prism is disposed so as to overlap the far display region 23 of the image projection unit 20.

[0025] Here, arranging the light branching unit 41 so as to overlap the image projection unit 20 means that the area where the light branching unit 41 is arranged overlaps with the image display area of ​​the image projection unit 20 in a planar view. Therefore, the first image light L1 irradiated from the far display area 23 is reflected by the light branching unit 41 on a path different from that of the second image light L2 and reaches the free-form surface mirror 44 after being reflected by the free-form surface mirror 42. In addition, the second image light L2 irradiated from the near display area 22 is reflected by the reflecting mirror 43 and reaches the free-form surface mirror 44.

[0026] The first image light L1 and the second image light L2 that reach the free-form surface mirror 44 are reflected upward to reach the windshield (not shown), where they are reflected and enter the viewpoint of the passenger. The projection optical unit 40 may be provided with a convex lens or a concave lens to expand or reduce the light diameter as needed. The arrangement and orientation of the light branching unit 41, the free-form surface mirror 42, the reflecting mirror 43, and the free-form surface mirror 44 are not limited to those shown in FIG. 2. A separate shielding plate for blocking external light may be provided on the optical path of the first image light L1 and / or the second image light L2 as needed.

[0027] The free-form surface mirror 42 is an optical member that receives the first image light L1 via the optical branching unit 41 and reflects the first image light L1 toward the free-form surface mirror 44. The reflective surface of the free-form surface mirror 42 is designed to expand the light diameter in the driver's viewing direction in order to project the light as a virtual image through the windshield. Here, the expansion of the light diameter in the viewing 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.

[0028] The reflecting mirror 43 is an optical member onto which the second image light L2 irradiated from the image irradiating unit 20 is incident and which reflects the second image light L2 toward the free-form surface mirror 44. In the example shown in FIG. 2, a convex mirror is shown as the reflecting mirror 43, but a mirror with an optical design necessary for projecting the second image light L2 as a virtual image can be used, and a concave mirror, a plane mirror, a free-form surface mirror, or the like can be used as necessary. Furthermore, the reflecting mirror 43 may be omitted, and the second image light L2 from the image irradiating unit 20 may be directly incident on the free-form surface mirror 44.

[0029] The free-form surface mirror 44 is a concave mirror that receives the first image light L1 and the second image light L2 and reflects the first image light L1 and the second image light L2 toward the windshield. The reflective surface of the free-form surface mirror 44 is designed to expand the light diameter toward the driver's viewpoint in order to project a virtual image through the windshield. Here, the expansion of the light diameter toward the viewpoint includes not only the case where the light diameter consistently expands after reflection, but also the case where the light diameter shrinks and expands after forming an image at an intermediate point.

[0030] The windshield (not shown) is a part provided in front of the driver's seat of the vehicle that transmits visible light. The windshield, on the inside surface of the vehicle, reflects the first image light L1 and the second image light L2 incident from the free-form surface mirror 44 toward the viewpoint and transmits light from outside the vehicle toward the viewpoint, and therefore corresponds to the display unit of the present invention. Although an example in which the windshield is used as the display unit is shown here, a combiner may be provided as a display unit separate from the windshield and reflect light from the free-form surface mirror 44 toward the viewpoint. Furthermore, the display unit is not limited to being located at the 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.

[0031] The virtual image is an image that appears as if it were formed in space when the first image light L1 and the second image light L2 reflected by the windshield reach the viewpoint (eyebox) of the driver, etc. The position at which the virtual image is formed is determined by the spread angle of the light irradiated from the image irradiator 20 as it travels toward the viewpoint after being reflected by the free-form surface mirror 42, the reflecting mirror 43, the free-form surface mirror 44, and the windshield.

[0032] In the image projection device 100 shown in FIG. 2, a prism serving as the optical branching unit 41 is disposed at a position overlapping the far display region 23, thereby branching the paths of the first image light L1 from the far display region 23 and the second image light L2 from the near display region 22. The first image displayed in the far display region 23 reaches the occupant's viewpoint via the optical branching unit 41, the free-form surface mirror 42, the free-form surface mirror 44, and the windshield. The second image displayed in the near display region 22 reaches the occupant's viewpoint via the reflecting mirror 43, the free-form surface mirror 44, and the windshield. The first image light L1 and the second image light L2 each have their light diameters expanded by the projection optical unit 40 before reaching the viewpoint, so the occupant perceives virtual images of the first image light L1 and the second image light L2 as if they were formed at a predetermined distance. Here, the position of the virtual image of the first image is farther from the viewpoint than the position of the virtual image of the second image.

[0033] FIG. 3 is a schematic plan view showing an example of the shutter unit 30 according to this embodiment. In the example shown in FIG. 3, the shutter unit 30 is a rotating body made of a substantially circular flat plate-like member, and is provided with a light-shielding unit 31, a near opening 32, and a far opening 33. The light-shielding unit 31 is made of a light-blocking material and blocks the first image light L1, the second image light L2, and external light that reach the light-shielding unit 31. The near opening 32 is an opening provided in a position overlapping the near display region 22. The far opening 33 is an opening provided in a position overlapping the far display region 23. Since the near opening 32 and the far opening 33 are openings provided in the shutter unit 30, they transmit light and correspond to the light-transmitting portion in the present invention. Here, the near opening 32 and the far opening 33 are shown as openings that are transparent, but the shutter section 30 may be made of a light-transmitting material, and a light-shielding layer that does not transmit light may be formed in the light-shielding section 31, and the area where the light-shielding layer is not formed may be used as the transparent section.

[0034] The shutter unit 30 also includes a motor unit (not shown) as a drive unit, which rotates the shutter unit 30 at a predetermined rotational speed in accordance with a control signal from the control unit 50, thereby enabling switching between the transmission mode and the blocking mode. The mechanism by which the motor unit rotates the shutter unit 30 is not limited, and the central axis of the shutter unit 30 may be directly connected to the rotating shaft of the motor unit, or may be driven via some kind of gear mechanism. Alternatively, a rotor may be brought into contact with the outer periphery of the shutter unit 30, and the rotor may be rotated by the motor unit, thereby indirectly rotating the shutter unit 30. The configuration of the motor unit is not limited, but using a stepping motor allows the rotational speed and phase to be controlled, thereby enabling accurate switching between the transmission mode and the blocking mode of the shutter unit 30.

[0035] 4A and 4B are schematic diagrams illustrating the transmission mode and blocking mode of the shutter unit 30, in which FIG. 4A shows the display area in the image projection unit 20, FIG. 4B shows the transmission mode, and FIG. 4C shows the blocking mode. As shown in FIG. 4A, a near display area 22 and a far display area 23 are provided at different positions in the entire display area 21 of the image projection unit 20. If the only areas in the entire display area 21 that display images are the near display area 22 and the far display area 23, a light-blocking member may be provided in the entire display area 21 to form openings corresponding to the near display area 22 and the far display area 23.

[0036] The near display area 22 is an area irradiated with second image light L2 containing a near image that is perceived as if it were formed at a position relatively close to the occupant, and corresponds to the second irradiation area in the present invention. The far display area 23 is an area irradiated with first image light L1 containing a far image that is perceived as if it were formed at a position relatively far from the occupant, and corresponds to the first irradiation area in the present invention. As described above, the first image light L1 and the second image light L2 are reflected by the projection optical unit 40 and the windshield, respectively, to reach the occupant's viewpoint. Therefore, the near display area 22 and the far display area 23 on the image irradiator 20 are distorted areas as shown in FIG. 4(a) so that they become rectangular virtual images after reflection by the windshield.

[0037] As shown in FIG. 4( b), in the transmission mode of the shutter unit 30, the near opening 32 overlaps the near display region 22, and the far opening 33 overlaps the far display region 23. Therefore, the second image light L2 emitted from the near display region 22 passes through the near opening 32 and enters the light branching unit 41, where it is reflected by the free-form surface mirror 42, the free-form surface mirror 44, and the windshield to form a near image as a virtual image. Similarly, the first image light L1 emitted from the far display region 23 passes through the far opening 33 and enters the reflecting mirror 43, where it is reflected by the free-form surface mirror 44 and the windshield to form a far image as a virtual image. At this time, the first image light L1 and the second image light L2 pass through the near opening 32 and the far opening 33, which have high transmittance, and therefore there is little attenuation of the light amount, thereby increasing the brightness of the projected virtual image.

[0038] Here, the near opening 32 and the far opening 33 are formed in a shape with a fan-like curvature along the circumferential direction of the disc-shaped shutter unit 30. Therefore, as shown in Fig. 4(b), it is preferable to arrange the shutter unit 30 so that the curvature direction of the near opening 32 and the far opening 33 coincides with the distortion direction of the near display region 22 and the far display region 23. Furthermore, since the far display region 23 is often larger in area than the near display region 22, it is preferable to provide the near opening 32 on the inner periphery side and the far opening 33 on the outer periphery side of the disc-shaped shutter unit 30.

[0039] As shown in FIG. 4(c), when the shutter unit 30 is in the blocking mode, the shading unit 31 overlaps the near display area 22 and the far display area 23. Therefore, external light that reaches the shutter unit 30 from the windshield via the projection optical unit 40 is blocked by the shading unit 31 and does not reach the image projection unit 20. This reduces the amount of external light that reaches the image projection unit 20, making it possible to suppress temperature rise and deterioration of the image projection unit 20.

[0040] As described above, in the image projection device 100 of this embodiment, the shutter unit 30 switches between transmitting and blocking light, so that it is possible to appropriately select between a transmission mode in which image light from the image irradiation unit 20 is transmitted to project an image, and a blocking mode in which external light is blocked to suppress a rise in temperature in the image irradiation unit 20, making it possible to suppress a rise in temperature in the image irradiation unit 20 due to external light.

[0041] (Modification of the first embodiment) Next, a modified example of the first embodiment of the present invention will be described with reference to FIG. 5. Description of content that overlaps with the first embodiment will be omitted. This modified example differs from the first embodiment in that the light source unit 10 is pulse-driven by PWM control to save power, and repeatedly turns on and off at a predetermined duty ratio. FIG. 5 is a timing chart for this modified example, where FIG. 5(a) shows the opening and closing timing of the shutter unit 30, and FIG. 5(b) shows the turning on and off timing of the light source unit 10.

[0042] As shown in Figures 5(a) and 5(b), the shutter unit 30 is in a closed state, i.e., a blocking mode, when the light source unit 10 is turned off, and is in an open state, i.e., a transmission mode, when the light source unit 10 is turned on. By switching the shutter unit 30 between the transmission mode and the blocking mode as shown in Figures 4(b) and 4(c), the shutter unit 30 is switched between open and closed states as shown in Figure 5(a). At this time, the control unit 50 may control the rotation of the motor unit to rotate the shutter unit 30 only when switching between open and closed states, or may rotate the shutter unit 30 continuously at a constant speed.

[0043] When the light source unit 10 is turned off, no light is emitted from the light source unit 10, and therefore the image displayed on the image projection unit 20 is not projected as a virtual image. Therefore, by synchronizing the turning-off timing of the light source unit 10 with the blocking mode of the shutter unit 30, external light does not reach the image projection unit 20 during the time when it is not contributing to the projection of a virtual image, and temperature rise and deterioration of the image projection unit 20 due to external light can be suppressed.

[0044] Furthermore, since light is emitted from the light source unit 10 at the timing when the light source unit 10 is turned on, the image displayed on the image projection unit 20 is projected as a virtual image. Therefore, by synchronizing the timing when the light source unit 10 is turned on with the transmission mode of the shutter unit 30, the first image light L1 and the second image light L2 are projected without being attenuated during the time that contributes to the projection of the virtual image, and the brightness of the projected virtual image can be improved.

[0045] 5 shows an example in which the duty ratio, which is the ratio of the lighting time of the light source unit 10 to the total time, is set to 50%, but the brightness may be adjusted by changing the duty ratio of the light source unit 10. In that case, it is preferable to change the duty ratio within a range in which the lighting period of the light source unit 10 is included in the period in which the shutter unit 30 is in the transmissive mode.

[0046] In the shutter unit 30 shown in Fig. 3, the light-blocking portion 31 is provided within an angular range of 180 degrees, resulting in an opening / closing duty ratio of 50%. However, if the shutter unit 30 is rotated at a constant rotation speed to alternate between the transmission mode and the blocking mode, the duty ratio may be set by changing the proportion of the light-blocking portion 31 provided. As an example, if the light-blocking portion 31 is provided within a range of 90 degrees and the near opening 32 and the far opening 33 are provided within a range of 270 degrees, the opening / closing duty ratio can be set to 75%.

[0047] In addition, in the example shown in Figures 5(a) and (b), the timing of switching the shutter unit 30 between open and closed coincides with the timing of turning the light source unit 10 on and off, but the timing can be selected so that they overlap each other, so that the transmission mode is included in the on period and the blocking mode is included in the off period.

[0048] As described above, in the image projection device 100 of this modified example, the image projection unit 20 irradiates image light by pulse driving the light source unit 10, which repeatedly turns on and off, and the shutter unit 30 selects the transmission mode during the light-on period and the blocking mode during the light-off period. This makes it possible to improve the brightness in the transmission mode while suppressing the temperature rise and deterioration of the image projection unit 20 due to external light in the blocking mode.

[0049] (Second embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. 6. Description of content that overlaps with the first embodiment will be omitted. This embodiment differs from the first embodiment in that transmission and blocking of the first image light L1 and the second image light L2 are set separately. FIG. 6 is a schematic diagram showing the relationship between the configuration of the shutter unit 30 and the image irradiation unit 20 according to this embodiment, with FIG. 6(a) showing the full transmission mode, FIG. 6(b) showing the far blocking mode, FIG. 6(c) showing the full blocking mode, and FIG. 6(d) showing the near blocking mode.

[0050] 6(a) to 6(d), in the shutter unit 30 of this embodiment, the near opening 32 and the far opening 33 are provided at positions that differ by 90 degrees. Similarly, the light blocking unit 31 includes a far light blocking portion 31a and a near light blocking portion 31b, and the far light blocking portion 31a and the near light blocking portion 31b are provided at positions that differ by 90 degrees.

[0051] 6(a), the near opening 32 overlaps with the near display region 22, and the far opening 33 overlaps with the far display region 23. Therefore, the first image light L1 and the second image light L2 pass through the near opening 32 and the far opening 33, which have high transmittance, and therefore the attenuation of the light amount is small, and the brightness of the projected virtual image can be increased.

[0052] 6(b), the near opening 32 overlaps the near display region 22, and the far light-shielding portion 31a overlaps the far display region 23. Therefore, the second image light L2 from the near display region 22 passes through the near opening 32, which has high transmittance, and therefore the attenuation of the light amount is small, thereby increasing the brightness of the projected virtual image. In addition, since the temperature rise of the image irradiator 20 due to external light tends to be significant in the far display region 23, the control unit 50 can effectively suppress the temperature rise in the far display region 23 by selecting the far blocking mode.

[0053] 6(c), near light-shielding portion 31b overlaps near display area 22, and far light-shielding portion 31a overlaps far display area 23. Therefore, external light that reaches shutter unit 30 from the windshield via projection optical unit 40 is blocked by near light-shielding portion 31b and far light-shielding portion 31a and does not reach image projection unit 20. This reduces the amount of external light that reaches image projection unit 20, making it possible to suppress temperature rise and deterioration of image projection unit 20.

[0054] 6(d), the near shading portion 31b overlaps the near display region 22, and the far opening 33 overlaps the far display region 23. Therefore, the first image light L1 from the far display region 23 passes through the far opening 33, which has high transmittance, and therefore the attenuation of the light amount is small, thereby increasing the brightness of the projected virtual image. Furthermore, by the control unit 50 selecting the near shading mode, it is possible to effectively suppress a temperature rise in the near display region 22.

[0055] As described above, in the image projection device 100 of this embodiment, the control unit 50 selects the shading mode of the shutter unit 30 depending on the area in the image projection unit 20 where it is desired to suppress a temperature rise and the display area of ​​the projected virtual image where it is desired to increase the brightness, thereby realizing suppression of a temperature rise in the image projection unit 20 and improvement of the brightness in response to a variety of situations.

[0056] (Third embodiment) Next, a third embodiment of the present invention will be described with reference to FIG. 7. Description of content that overlaps with the first embodiment will be omitted. This embodiment differs from the first embodiment in that the image light is intermediately imaged in the projection optical unit 40, and the shutter unit 30 is disposed at the intermediate image position. FIG. 7 shows an example of the configuration of an image projection device 100 according to this embodiment, with FIG. 7(a) being a schematic cross-sectional view of the entire device, and FIG. 7(b) being a schematic perspective view showing an example of the shutter unit 30.

[0057] 7(a) and 7(b), the image projection device 100 of this embodiment includes a light source unit 10, an image projection unit 20, a shutter unit 30, and an external light blocking unit 60. The projection optical unit 40 also includes a free-form surface mirror 42 and a free-form surface mirror 44. Image light emitted from the image projection unit 20 is reflected by the free-form surface mirror 42 and the free-form surface mirror 44 to reach the windshield and be projected in the direction of the passenger's viewpoint. At least one axial component of the image light reflected by the free-form surface mirror 42 is collected at an intermediate imaging position before reaching the free-form surface mirror 44, and after being collected at the intermediate imaging position, the light reaches the free-form surface mirror 44 while expanding.

[0058] The external light blocking unit 60 is a member made of a light-blocking material and has an opening at the intermediate image position. By locating the external light blocking unit 60 at the intermediate image position, it is possible to block the components of external light that enters through the windshield but does not reach the image projection unit 20, thereby preventing the occurrence of stray light.

[0059] 7(a) and 7(b), the shutter section 30 is made of a light-blocking material and is formed in a substantially cylindrical shape. Openings 35a and 35b are provided at positions facing each other on the side surface of the shutter section 30. The side surface of the shutter section 30 corresponds to the light-blocking section in the present invention, and the openings 35a and 35b correspond to the light-transmitting section in the present invention.

[0060] The shutter unit 30 is disposed at the intermediate image position of the free-form surface mirror 42 so that image light formed as an intermediate image can pass through the openings 35a and 35b. The shutter unit 30 is driven to rotate by a drive unit around the central axis of the cylinder as the axis of rotation, and the positions of the side surfaces and openings 35a and 35b can be switched. Therefore, when the side surfaces of the shutter unit 30 are located on the optical path of the image light, the shutter unit is in blocking mode, and when the openings 35a and 35b are located, the shutter unit is in transmission mode.

[0061] In the image projection device 100 of this embodiment, the shutter unit 30 also switches between transmitting and blocking light, so that it is possible to appropriately select between a transmission mode in which image light from the image projection unit 20 is transmitted to project an image, and a blocking mode in which external light is blocked to suppress a temperature rise in the image projection unit 20, making it possible to suppress a temperature rise in the image projection unit 20 due to external light. Furthermore, by providing the shutter unit 30 at an intermediate imaging position, it is possible to reduce the size and weight of the shutter unit 30 and the image projection device 100.

[0062] (Fourth embodiment) Next, a fourth embodiment of the present invention will be described with reference to Fig. 8. Description of content that overlaps with the first embodiment will be omitted. Fig. 8 is a schematic diagram showing an example of the configuration of the shutter unit 30 according to this embodiment, Fig. 8(a) shows an example of a substantially rectangular configuration, and Fig. 8(b) shows an example of a configuration in which a blocking mode is provided only in a partial area.

[0063] 8(a), a part of the disk shape is cut out, and the cutout portion 36 is used as the light-transmitting portion, and the remaining substantially rectangular portion is used as the light-blocking portion 31. Even with such a simple shape, the light-transmitting portion of the cutout portion 36 and the light-blocking portion 31 can be switched by rotating the shutter portion 30.

[0064] 8(b), a near opening 32 is provided over 360 degrees on the inner periphery of the disk, and a far opening 33 is provided over 180 degrees on the outer periphery. Temperature rise in the image irradiation unit 20 due to external light tends to be more pronounced in the far display region 23, so by switching between a light-blocking mode and a transmission mode only for the far display region 23, it is possible to effectively suppress temperature rise and deterioration in the far display region 23. Furthermore, since no light-blocking unit 31 is provided for the near display region 22 and the transmission mode is always used, it is also possible to improve the brightness of the near image.

[0065] 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]

[0066] 100...Image projection device 10...Light source section 20...Image irradiation unit 30...Shutter section 40...Projection optical section 50...Control unit 60...External light blocking section 21…Full display area 22…Near display area 23…Far display area 31...Light blocking part 31a...Far light shielding part 31b...Near light shielding part 32...Near aperture 33…Far aperture 35a, 35b…opening 36...Notched part 41...Optical branching section 42, 44...Freeform mirror 43...Reflector

Claims

1. An image projection device that projects a projection image onto a display unit for displaying a virtual image, an image irradiating unit that irradiates image light; a projection optical unit that projects the image light as the projected image in a viewing direction via the display unit; a shutter unit that is disposed on an optical path of the image light between the image irradiation unit and the display unit and that switches between a transmission mode in which light is transmitted and a blocking mode in which light is blocked, the image projection unit includes a first projection area for projecting a first image and a second projection area for projecting a second image at different positions within the entire display area; the projection optical unit includes a first optical unit that projects the first image onto the display unit and a second optical unit that projects the second image onto the display unit; The image projection device, wherein the shutter section selects the transmission mode and the blocking mode for each of the first irradiation area and the second irradiation area.

2. The image projection device according to claim 1, the shutter unit includes a first light-transmitting unit, a second light-transmitting unit, a rotating body including a light-shielding unit, and a driving unit that drives the rotating body to rotate; the first light transmitting portion is provided at a position overlapping the first illumination region, The image projection device, wherein the second light-transmitting portion is provided at a position overlapping the second illumination area.

3. An image projection device according to claim 1 or 2, The shutter portion has a disk shape, The image projection device, wherein the first light-transmitting portion and the second light-transmitting portion are formed in a fan shape along a circumferential direction of the disk shape.

4. An image projection device that projects a projection image onto a display unit for displaying a virtual image, an image irradiating unit that irradiates image light; a projection optical unit that projects the image light as the projected image in a viewing direction via the display unit; a shutter unit that is disposed on an optical path of the image light between the image irradiation unit and the display unit and that switches between a transmission mode in which light is transmitted and a blocking mode in which light is blocked, the projection optical unit forms an image of the image light at an intermediate image-forming position on the optical path; The image projection device is characterized in that the shutter section is disposed at the intermediate image forming position.

5. 5. The image projection device according to claim 4, The image projection device is characterized in that the shutter section includes a cylindrical rotating body having a light-transmitting section and a light-blocking section, and a drive section that drives the rotating body to rotate.

6. 6. The image projection device according to claim 1, the image irradiating unit irradiates the image light by pulse driving that repeatedly turns on and off; The image projection device, wherein the shutter section selects the transmission mode during a light-on period of the pulse driving, and the blocking mode during a light-off period of the pulse driving.

Images