Image projection device

Abstract

An image projection device (20) that makes an occupant of a moving body visually recognize an image as a virtual image comprises a control unit (25) configured so as to switch between a first image (Ia) projected to a first position and a second image (Ib) projected to a second position different from the first position, on the basis of the movement speed of the moving body (1). The control unit (25) sets the movement speed of the moving body (1) when switching from the first image (Ia) to the second image (Ib) to be different from the movement speed of the moving body (1) when switching from the second image (Ib) to the first image (Ia).

Description

Image Projection Device

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

[0002] Patent Document 1 discloses a head-up display (HUD) in which light for forming an image emitted from an image generation unit is reflected by a concave mirror and incident on the windshield of a vehicle, causing the occupant to perceive the image as a virtual image.

[0003] Japanese Patent Application Publication No. 2019-166891

[0004] The HUD in Patent Document 1 changes the position where a virtual image of predetermined information is projected based on the relationship between the vehicle speed and stopping distance, but does not disclose any information about the display positions of the multiple pieces of information displayed by the virtual images or how to change the display positions.

[0005] An object of the present disclosure is to provide an image projection device that can improve the visibility of a plurality of images that are visually recognized by an occupant as virtual images.

[0006] An image projection device according to one aspect of the present disclosure is an image projection device that allows an occupant of a moving body to view an image as a virtual image, and includes a control unit configured to switch between a first image projected at a first position and a second image projected at a second position different from the first position based on the moving speed of the moving body, and the control unit differentiates the moving speed of the moving body when switching from the first image to the second image from the moving speed of the moving body when switching from the second image to the first image.

[0007] According to the present disclosure, the first image or the second image can be displayed in accordance with the line of sight of the occupant, thereby improving the visibility of multiple images that are viewed by the occupant as virtual images.

[0008] According to the present disclosure, it is possible to improve the visibility of a plurality of images that are visually recognized by an occupant as virtual images.

[0009] FIG. 1 is a schematic diagram showing a configuration of a head-up display (HUD) according to an embodiment; FIG. 2 is a diagram for explaining a virtual image object displayed by the HUD; FIG. 3 is a diagram showing a flow of control executed by a control unit; FIG. 4 is a diagram for explaining a virtual image object displayed by the HUD; FIG. 5 is a diagram for explaining a virtual image object displayed by the HUD; FIG. 6 is a diagram for explaining a virtual image object displayed by the HUD; FIG. 7 is a diagram for explaining a virtual image object displayed by the HUD; FIG. 8 is a diagram for explaining a virtual image object displayed by the HUD;

[0010] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. For convenience of explanation, the dimensions of each component shown in the drawings may differ from the actual dimensions of each component. In addition, in the drawings, arrow U indicates the upward direction of the illustrated structure. Arrow D indicates the downward direction of the illustrated structure. Arrow F indicates the forward direction of the illustrated structure. Arrow B indicates the rearward direction of the illustrated structure. Arrow L indicates the leftward direction of the illustrated structure. Arrow R indicates the rightward direction of the illustrated structure. These directions are relative directions set for the head-up display (HUD) 20 shown in FIG. 1.

[0011] 1 is a schematic diagram of a HUD 20 according to an embodiment, viewed from the side of a vehicle 1. The HUD 20 is provided in the vehicle 1. The vehicle 1 is an example of a moving body. For example, the HUD 20 is disposed in the dashboard of the vehicle 1. The HUD 20 is an example of an image projection device.

[0012] The vehicle 1 is configured to be able to execute a driving assistance function. The term "driving assistance" used in this specification refers to a control process that at least partially performs at least one of driving operations (steering, acceleration, deceleration), monitoring of the driving environment, and backup of driving operations. In other words, "driving assistance" encompasses everything from partial driving assistance such as a speed maintenance function, a distance maintenance function, a collision damage mitigation braking function, and a lane keep assist function to fully automated driving operations.

[0013] The HUD 20 functions as a visual interface between the vehicle 1 and the occupants of the vehicle 1. Specifically, the HUD 20 is configured to display predetermined information as a predetermined image so that the information is superimposed on the real space outside the vehicle 1 (particularly, the surrounding environment in front of the vehicle 1). The predetermined image may include a still image or a moving image (video). The information displayed by the HUD 20 is, for example, information related to the traveling of the vehicle 1.

[0014] 1, the HUD 20 includes a HUD main body 21. The HUD main body 21 has a housing 22 and an exit window 23. The exit window 23 is made of a transparent plate that transmits visible light. The HUD main body 21 has, inside the housing 22, an image generation unit (PGU) 24, a control unit 25, a concave mirror 26, and a lens 27. The concave mirror 26 is an example of a reflecting unit.

[0015] The image generating unit 24 is configured to emit light for generating a predetermined image. The image generating unit 24 is fixed to the housing 22. The light emitted from the image generating unit 24 is, for example, visible light. Although detailed illustrations are omitted, the image generating unit 24 includes a light source, optical components, and a display device. The light source is, for example, an LED light source or a laser light source. The LED light source is, for example, a white LED light source. The laser light source is, for example, an RGB laser light source configured to emit red laser light, green laser light, and blue laser light, respectively. The optical components include a prism, a lens, a diffuser, a magnifying glass, etc. as appropriate. The optical components transmit the light emitted from the light source and emit it toward the display device. The display device is, for example, a liquid crystal display, a DMD (Digital Mirror Device), etc. The drawing method of the image generation unit 24 may be a raster scan method, a DLP (Digital Light Processing) method, or an LCOS (Liquid Crystal On Silicon) method. When the DLP method or the LCOS method is adopted, the light source of the image generation unit 24 may be an LED light source. Note that when the liquid crystal display method is adopted, the light source of the image generation unit 24 may be a white LED light source.

[0016] The control unit 25 controls the operation of each unit of the HUD 20. The control unit 25 is connected to a vehicle control unit (not shown) of the vehicle 1. The control unit 25 generates a control signal for controlling the operation of the image generation unit 24 based on, for example, information related to vehicle driving transmitted from the vehicle control unit, and transmits the generated control signal to the image generation unit 24. Examples of information related to vehicle driving include vehicle driving state information related to the driving state of the vehicle and surrounding environment information related to the surrounding environment of the vehicle 1. The vehicle driving state information may include speed information of the vehicle 1, position information of the vehicle 1, or remaining fuel amount information of the vehicle 1. The surrounding environment information may include information on objects (pedestrians, other vehicles, signs, etc.) present outside the vehicle 1. The surrounding environment information may include information on attributes of objects present outside the vehicle 1, and information on the distance and position of the objects relative to the vehicle 1.

[0017] The control unit 25 is equipped with a processor such as a CPU (Central Processing Unit) and a memory, and the processor executes a computer program read from the memory to control the operation of the image generation unit 24, etc. The control unit 25 may be configured integrally with a vehicle control unit. In this regard, the control unit 25 and the vehicle control unit may be configured as a single electronic control unit.

[0018] The concave mirror 26 is disposed on the optical path of the light emitted from the image generation unit 24. Specifically, the concave mirror 26 is disposed in front of the image generation unit 24 inside the housing 22. The concave mirror 26 is configured to reflect the light emitted from the image generation unit 24 toward the windshield 18 (e.g., the front window of the vehicle 1). The concave mirror 26 has a reflective surface that is concavely curved. The concave mirror 26 reflects the image of the light emitted from the image generation unit 24 and formed thereon at a predetermined magnification. The concave mirror 26 can be configured to be rotatable by a drive mechanism (not shown).

[0019] The lens 27 is disposed between the image generator 24 and the concave mirror 26. The lens 27 is configured to change the focal length of light emitted from the light emission surface 241 of the image generator 24. The lens 27 is disposed at a position through which a portion of the light emitted from the light emission surface 241 of the image generator 24 and directed toward the concave mirror 26 passes. The lens 27 may include, for example, a drive unit and be configured to change the distance from the image generator 24 in response to a control signal generated by the control unit 25. Movement of the lens 27 changes the focal length (apparent optical path length) of the light emitted from the image generator 24, thereby changing the distance between the windshield 18 and the predetermined image displayed by the HUD 20. Note that a mirror, for example, may be used as an optical element instead of the lens 27.

[0020] 1 , light emitted from the image generation unit 24 is reflected by the concave mirror 26 and emitted from the exit window 23 of the HUD main body 21. The light emitted from the exit window 23 of the HUD main body 21 is irradiated onto the windshield 18. A portion of the light irradiated from the exit window 23 onto the windshield 18 is reflected toward the occupant's viewpoint E. As a result, the occupant perceives the light emitted from the HUD main body 21 as a virtual image (predetermined image) formed at a predetermined distance in front of the windshield 18. In this way, the image displayed by the HUD 20 is superimposed on the real space in front of the vehicle 1 through the windshield 18, and as a result, the occupant can visually perceive the virtual image objects Ia and Ib formed by the predetermined image as floating above the road outside the vehicle.

[0021] For example, light (an example of first light) emitted from point Pa1 on the light emission surface 241 of the image generation unit 24 travels along optical path La1, is reflected at point Pa2 on the concave mirror 26, travels along optical path La2, and is emitted to the outside of the HUD 20 through the exit window 23 of the HUD main body 21. The light that has traveled along optical path La2 is incident on point Pa3 on the windshield 18, thereby forming part of a virtual image object Ia (an example of a first image) formed by a predetermined image. The virtual image object Ia is formed, for example, a relatively short predetermined distance forward from the windshield 18. The virtual image object Ia is formed, for example, about 3 m forward from the windshield 18.

[0022] On the other hand, light (an example of second light) emitted from point Pb1 on the light emission surface 241 of the image generation unit 24 travels along optical path Lb1 after passing through the lens 27. The focal length of the light emitted from point Pb1 changes as it passes through the lens 27. That is, the apparent optical path length of the light emitted from point Pb1 is lengthened as it passes through the lens 27. The light traveling along optical path Lb1 is reflected at point Pb2 on the concave mirror 26, then travels along optical path Lb2, and is emitted to the outside of the HUD 20 through the exit window 23 of the HUD main body 21. The light traveling along optical path Lb2 is incident on point Pb3 on the windshield 18, thereby forming part of a virtual image object Ib (an example of a second image) formed by a predetermined image. The virtual image object Ib is formed, for example, above the virtual image object Ia and further forward from the windshield 18 than the virtual image object Ia. The virtual image object Ib is formed, for example, about 15 m in front of the windshield 18. The distance of the virtual image object Ib (the distance from the windshield 18 to the virtual image) can be adjusted appropriately by adjusting the position of the lens 27.

[0023] When forming 2D images (planar images) as the virtual image objects Ia and Ib, a predetermined image is projected to become a virtual image at a single distance that is arbitrarily determined. When forming 3D images (stereoscopic images) as the virtual image objects Ia and Ib, a plurality of predetermined images, which may be the same or different from one another, are projected to become virtual images at different distances.

[0024] 2, the virtual image object Ia is displayed below the vehicle in front of the vehicle, and the virtual image object Ib is displayed above the vehicle in front of the vehicle. In this way, it is preferable that the display areas of the virtual image objects Ia and Ib are displayed at positions that do not overlap with the preceding vehicle 100. As described above, the virtual image object Ib is formed further forward from the windshield 18 than the virtual image object Ia, and is visually recognized by the occupant as a smaller image than the virtual image object Ia.

[0025] The virtual image object Ia includes, for example, a vehicle speed image Ia1 indicating the current speed of the vehicle 1, a sign image Ia2 indicating sign information for the road on which the vehicle 1 is currently traveling, a status image Ia3 indicating the current vehicle state of the vehicle 1, and a navigation image Ia4 indicating the traveling direction (right turn, left turn, or straight ahead) of the vehicle 1. In Fig. 2, the navigation image Ia4 indicates that the traveling direction of the vehicle is straight ahead. The virtual image object Ib includes, for example, a vehicle speed image Ib1 indicating the current speed of the vehicle 1 and a sign image Ib2 indicating sign information for the road on which the vehicle 1 is currently traveling.

[0026] Either one or both of the virtual image objects Ia and Ib are displayed based on information related to the traveling of the vehicle 1. Specifically, the control unit 25 switches between a state in which only the virtual image object Ia is displayed, a state in which both the virtual image object Ia and the virtual image object Ib are displayed, and a state in which only the virtual image object Ib is displayed, based on information related to the traveling of the vehicle 1.

[0027] 3 to 10, the display control of the virtual image objects Ia and Ib executed by the control unit 25 will be described. In this example, the control using the speed information of the vehicle 1 as an example of information related to the traveling of the vehicle 1 will be described.

[0028] As illustrated in Fig. 3, the control unit 25 projects the virtual image object Ia with high brightness and hides (does not project) the virtual image object Ib (STEP 1). Next, the control unit 25 acquires speed information of the vehicle 1 (STEP 2). The control unit 25 acquires the speed information, for example, at predetermined time intervals. For example, as shown in Fig. 4, when the speed of the vehicle 1 is 82 km / h, the control unit 25 projects the virtual image object Ia with high brightness downward in front of the vehicle and hides (does not project) the virtual image object Ib. The virtual image object Ia projected in STEP 1 may include a vehicle speed image Ia1, a sign image Ia2, a status image Ia3, and a navigation image Ia4.

[0029] Next, the control unit 25 determines whether the vehicle speed V is equal to or greater than a first threshold value Vth1 (STEP 3). If it is determined that the vehicle speed V is less than the first threshold value Vth1 (NO in STEP 3), the control unit 25 keeps the virtual image object Ia projected at high brightness and keeps the virtual image object Ib hidden (unprojected). The first threshold value Vth1 can be set appropriately based on, for example, the vehicle speed at which the occupant's focal position is assumed to be farther away than the display distance of the virtual image object Ia. For example, the first threshold value Vth1 is 90 km / h.

[0030] When it is determined that the vehicle speed V is equal to or greater than the first threshold value Vth1 (YES in STEP 3), the control unit 25 adjusts the brightness, display position, and display range of the virtual image object Ia and the virtual image object Ib based on the speed information (STEP 4). Specifically, as illustrated in FIGS. 5 and 6, as the speed of the vehicle 1 increases, the brightness of the virtual image object Ia is decreased and the brightness of the virtual image object Ib is increased. Furthermore, as the speed of the vehicle 1 increases, at least a portion of the images included in the virtual image object Ia, for example, images Ia1 and Ia2, is moved slightly upward, and at least a portion of the images included in the virtual image object Ib, for example, images Ib1 and Ib2, is moved slightly upward. Furthermore, as the speed of the vehicle 1 increases, at least a portion of the images included in the virtual image object Ia, for example, the upper region of image Ia1, is hidden. That is, as the speed of the vehicle 1 increases, the control unit 25 moves the images Ia1 and Ia2 upward, while changing the display range of the image Ia1.

[0031] Specifically, as shown in FIG. 5 , when the speed of the vehicle 1 increases to, for example, 92 km / h, the control unit 25 moves the vehicle speed image Ia1 and the sign image Ia2 of the virtual image object Ia slightly upward from the state shown in FIG. 4 . The control unit 25 also projects the virtual image object Ib (vehicle speed image Ib1, sign image Ib2) at a lower brightness than the virtual image object Ia, farther up in front of the vehicle 1. As shown in FIG. 6 , when the speed of the vehicle 1 further increases to, for example, 95 km / h, the control unit 25 reduces the brightness of all images Ia1 to Ia4 included in the virtual image object Ia compared to the state shown in FIG. 5 , and moves the vehicle speed image Ia1 and the sign image Ia2 further upward. At this time, the control unit 25 gradually hides the upper regions of the images Ia1 and Ia2 in accordance with the upward movement of the vehicle speed image Ia1 and the sign image Ia2. That is, the control unit 25 controls the virtual image object Ia so that it is not displayed above a predetermined region. Furthermore, the control unit 25 increases the brightness of the virtual image object Ib (vehicle speed image Ib1, sign image Ib2) more than in the state of FIG. 5, and moves the virtual image object Ib slightly upward more than in the state of FIG.

[0032] Next, the control unit 25 determines whether the vehicle speed V is equal to or greater than a second threshold value Vth2 (STEP 5). The second threshold value Vth2 is a value that is higher than the first threshold value Vth1 by a predetermined value. For example, the second threshold value Vth2 is 100 km / h. If it is determined that the vehicle speed V is less than the second threshold value Vth2 (NO in STEP 5), the control unit 25 continues the processing of STEP 4.

[0033] When it is determined that the vehicle speed V is equal to or greater than the second threshold value Vth2 (YES in STEP 5), the control unit 25 hides (does not project) the virtual image object Ia and projects the virtual image object Ib at high brightness (STEP 6). As shown in Fig. 7, when the speed of the vehicle 1 further increases from the state shown in Fig. 6 to, for example, 100 km / h, the control unit 25 further reduces the brightness of the virtual image object Ia to be lower than the state shown in Fig. 6, thereby hiding the entire virtual image object Ia. Furthermore, the control unit 25 moves the virtual image object Ib further upward than the state shown in Fig. 6, and further increases the brightness of the virtual image object Ib to project it at high brightness.

[0034] Next, the control unit 25 determines whether the vehicle speed V is less than the third threshold value Vth3 (STEP 7). If it is determined that the vehicle speed V is equal to or greater than the third threshold value Vth3 (NO in STEP 7), the control unit 25 continues the processing of STEP 6. The third threshold value Vth3 is preferably lower than the first threshold value Vth1 and the second threshold value Vth2. For example, the third threshold value Vth3 is 85 km / h.

[0035] If it is determined that the vehicle speed V is less than the third threshold value Vth3 (YES in STEP 7), the control unit 25 adjusts the brightness, display position, and display range of the virtual image object Ia and the virtual image object Ib based on the speed information (STEP 8). Specifically, as illustrated in FIGS. 8 and 9, as the speed of the vehicle 1 decreases, the brightness of the virtual image object Ia is increased and the brightness of the virtual image object Ib is decreased. Furthermore, as the speed of the vehicle 1 decreases, at least a portion of the images included in the virtual image object Ia, for example, the vehicle speed image Ia1 and the sign image Ia2, are moved slightly downward, and the vehicle speed image Ib1 and the sign image Ib2 included in the virtual image object Ib are moved slightly downward. Furthermore, as the speed of the vehicle 1 decreases, the vehicle speed image Ia1 and the sign image Ia2 are gradually displayed from their lower regions.

[0036] As shown in FIG. 8 , when the speed of the vehicle 1 decreases to, for example, 75 km / h, the control unit 25 moves the virtual image object Ib (vehicle speed image Ib1 and sign image Ib2) slightly downward. The control unit 25 also moves the vehicle speed image Ia1 and sign image Ia2 of the virtual image object Ia slightly downward while projecting them at low brightness. At this time, the control unit 25 gradually displays the vehicle speed image Ia1 and sign image Ia2 from their lower regions in accordance with their downward movement. As shown in FIG. 9 , when the speed of the vehicle 1 further decreases to, for example, 65 km / h, the control unit 25 further decreases the brightness of the virtual image object Ib compared to the state shown in FIG. 8 and moves the virtual image object Ib further downward. The control unit 25 also increases the brightness of the vehicle speed image Ia1 and sign image Ia2 of the virtual image object Ia compared to the state shown in FIG. 8 and moves them further downward, displaying the entire images Ia1 and Ia2. As described above, the virtual image object Ia is controlled so that it is not displayed above a predetermined area, so that the vehicle speed image Ia1 and the sign image Ia2 are gradually displayed from the lower area as they gradually move downward from the state shown in Figure 5.

[0037] Next, the control unit 25 determines whether the vehicle speed V is less than a fourth threshold value Vth4 (STEP 9). The fourth threshold value Vth4 is a value that is lower than the third threshold value Vth3 by a predetermined value. For example, the fourth threshold value Vth4 is 60 km / h. If it is determined that the vehicle speed V is equal to or greater than the fourth threshold value Vth4 (NO in STEP 9), the control unit 25 continues the processing of STEP 8.

[0038] If it is determined that the vehicle speed V is less than the fourth threshold value Vth4 (YES in STEP 9), the control unit 25 projects the virtual image object Ia with high brightness and hides (does not project) the virtual image object Ib (STEP 10). Specifically, as shown in FIG. 10 , when the speed of the vehicle 1 decreases to, for example, 58 km / h, the control unit 25 projects not only the vehicle speed image Ia1 and the sign image Ia2, but also the status image Ia3 and the navigation image Ia4. The control unit 25 also further reduces the brightness of the virtual image object Ib compared to the state shown in FIG. 9 to hide the virtual image object Ib. As a result, the display mode of the virtual image object Ia and the virtual image object Ib returns to the initial state shown in FIG. 4, and the processing ends.

[0039] As described above, in the HUD 20 (an example of an image projection device) according to this embodiment, the control unit 25 is configured to project a virtual image object Ia (an example of a first image) at a lower position (an example of a first position) in front of the vehicle 1, and project a virtual image object Ib (an example of a second image) at an upper position (an example of a second position) in front of the vehicle 1. The control unit 25 projects the virtual image object Ia when the speed of the vehicle 1 is less than a first threshold Vth1 (an example of a first condition), projects the virtual image object Ib when the speed of the vehicle 1 is equal to or greater than a second threshold Vth2 that is higher than the first threshold Vth1 (an example of a second condition), and projects both the virtual image object Ia and the virtual image object Ib when the speed of the vehicle 1 is equal to or greater than the first threshold Vth1 but less than the second threshold Vth2 (an example of a third condition). This configuration makes it possible to switch between displaying the virtual image object Ia and the virtual image object Ib, or to overlap and display the virtual image object Ia and the virtual image object Ib, depending on the speed of the vehicle 1. This improves the visibility of the multiple images visually recognized by the occupant as virtual images. Furthermore, when switching between the projection of the virtual image object Ia and the virtual image object Ib in accordance with the speed of the vehicle 1, the virtual image object Ia and the virtual image object Ib are projected in an overlapping manner for a certain period of time. This reduces the sense of discomfort felt by the occupant.

[0040] When the speed of the vehicle 1 is equal to or greater than the first threshold value Vth1 and less than the second threshold value Vth2 and the vehicle 1 is accelerating, the control unit 25 decreases the luminance of the virtual image object Ia and increases the luminance of the virtual image object Ib. With this configuration, when the display switches from the virtual image object Ia to the virtual image object Ib while the vehicle 1 is accelerating, the sense of discomfort felt by the occupants can be further reduced.

[0041] Furthermore, when the display switches from the virtual image object Ia to the virtual image object Ib during acceleration of the vehicle 1, the control unit 25 moves at least a portion of the virtual image object Ia and at least a portion of the virtual image object Ib upward. In this example, the control unit 25 moves the images Ia1 and Ia2 included in the virtual image object Ia slightly upward, and moves the images Ib1 and Ib2 included in the virtual image object Ib slightly upward. In this way, when the display switches from the lower virtual image object Ia to the upper virtual image object Ib during acceleration of the vehicle 1, the images Ia1 and Ia2 and the images Ib1 and Ib2 are projected to move upward, respectively, thereby naturally guiding the occupant's line of sight from the virtual image object Ia to the virtual image object Ib.

[0042] Furthermore, when the display is switched from the virtual image object Ia to the virtual image object Ib during acceleration of the vehicle 1, the control unit 25 gradually hides at least a portion of the virtual image object Ia, for example, the image Ia1, from its upper region. This configuration allows the occupant's line of sight to be more naturally guided from the virtual image object Ia to the virtual image object Ib.

[0043] Furthermore, when the speed of the vehicle 1 is equal to or greater than the first threshold value Vth1 and less than the second threshold value Vth2 and the vehicle 1 is decelerating, the control unit 25 increases the brightness of the virtual image object Ia and decreases the brightness of the virtual image object Ib. With this configuration, when the display switches from the virtual image object Ib to the virtual image object Ia while the vehicle 1 is decelerating, the sense of discomfort felt by the occupants can be further reduced.

[0044] Furthermore, the control unit 25 moves at least a portion of the virtual image object Ia and at least a portion of the virtual image object Ib downward when the display switches from the virtual image object Ib to the virtual image object Ia during deceleration of the vehicle 1. In this way, when the display switches from the upper virtual image object Ib to the lower virtual image object Ia during deceleration of the vehicle 1, at least a portion of the virtual image object Ia and at least a portion of the virtual image object Ib are projected to move downward, thereby naturally guiding the line of sight of the occupant from the virtual image object Ib to the virtual image object Ia.

[0045] Furthermore, when the display is switched from the virtual image object Ib to the virtual image object Ia during deceleration of the vehicle 1, the control unit 25 gradually displays at least a portion of the virtual image object Ia from its lower region. This configuration makes it possible to more naturally guide the occupant's line of sight from the virtual image object Ib to the virtual image object Ia.

[0046] In this embodiment, the display of the virtual image object Ia located near and below the vehicle 1 and the virtual image object Ib located far and above the vehicle 1 are switched based on the speed information of the vehicle 1. However, this configuration is not limited to this. Instead of the speed information of the vehicle 1, the display of the virtual image object Ia and the virtual image object Ib may be switched based on the position information of the vehicle 1. For example, the control unit 25 may project the virtual image object Ia when it determines, based on the position information of the vehicle 1, that the vehicle 1 is traveling on an ordinary road (an example of a first condition), project the virtual image object Ib when it determines that the vehicle 1 is traveling on a motorway (e.g., a freeway) (an example of a second condition), and project the virtual image object Ia and the virtual image object Ib when it determines that the vehicle 1 is entering the motorway from an ordinary road (an example of a third condition). In this way, by switching the display of the virtual image object Ia and the virtual image object Ib when the vehicle 1 is traveling on an ordinary road and when it is traveling on a motorway, the visibility of these virtual image objects can be improved. Furthermore, when entering a motorway from an ordinary road, the virtual image object Ia and the virtual image object Ib are displayed in an overlapping manner, thereby reducing the sense of discomfort felt by the occupants.

[0047] In this embodiment, the moving speed of the vehicle 1 when switching from the virtual image object Ia to the virtual image object Ib is different from the moving speed of the vehicle 1 when switching from the virtual image object Ib to the virtual image object Ia. That is, the moving speed that serves as the threshold for switching is different between when the virtual image object Ib is projected in place of the virtual image object Ia and when the virtual image object Ia is projected in place of the virtual image object Ib.

[0048] Incidentally, when accelerating, occupants often shift their gaze from the near area of ​​the vehicle 1 to the distant area at a relatively early timing. On the other hand, when decelerating, occupants often keep their gaze on the distant area of ​​the vehicle 1 until the vehicle speed slows to a certain extent. Therefore, in this embodiment, the control unit 25 preferably sets the speed of the vehicle 1 when switching from the virtual image object Ia to the virtual image object Ib higher than the speed of the vehicle 1 when switching from the virtual image object Ib to the virtual image object Ia. In this way, by setting the speed threshold for switching from the virtual image object Ia to the virtual image object Ib when accelerating higher than the speed threshold for switching from the virtual image object Ib to the virtual image object Ia when decelerating, it is possible to switch the display of the virtual image object Ia and the virtual image object Ib, for example, in a manner that appropriately follows the natural movement of the occupant's gaze. This reduces the sense of discomfort felt by the occupant.

[0049] Although the embodiments of the present disclosure have been described above, it goes without saying that the technical scope of the present invention should not be construed 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 invention should be determined based on the scope of the invention described in the claims and its equivalents.

[0050] The positions and ranges of the information displayed on the virtual image objects Ia and Ib are not limited to those shown in Figures 2 and 4 to 10. In addition, in the above embodiment, the control unit 25 adjusts the brightness, display position, and display range of the virtual image objects Ia and Ib based on the speed information and position information of the vehicle 1, but this is not limiting. The control unit 25 may adjust at least one of the brightness, display position, and display range of the virtual image objects Ia and Ib based on the speed information and position information of the vehicle 1.

[0051] The virtual image objects Ia and Ib are displayed based on the speed information or the position information of the vehicle 1. However, based on information related to the traveling of the vehicle other than the above information, the display of the virtual image objects Ia and Ib may be switched, or the virtual image objects Ia and Ib may be displayed simultaneously.

[0052] The light for generating the virtual image object Ia and the light for generating the virtual image object Ib are emitted from one image generation unit 24. However, the HUD 20 may be configured to include a plurality of image generation units, and the light for generating the virtual image object Ia and the light for generating the virtual image object Ib may be configured to be emitted from different image generation units.

[0053] The light emitted from the image generating unit 24 may be configured to be incident on the concave mirror 26 via an optical component such as a plane mirror.

[0054] The light emitted from the image generation unit 24 is configured to be reflected by the concave mirror 26 and irradiated onto the windshield 18, but is not limited to this. For example, the light reflected by the concave mirror 26 may be irradiated onto a combiner (not shown) provided inside the windshield 18. The combiner is formed, for example, of a transparent plastic disk. A portion of the light irradiated onto the combiner from the image generation unit 24 of the HUD main body 21 is reflected toward the occupant's viewpoint E, similar to when light is irradiated onto the windshield 18.

[0055] As described above, the present specification discloses the following: (1) An image projection device that allows a passenger of a moving body to view an image as a virtual image, the image projection device including a control unit configured to project a first image and project a second image at a position different from the first image, the control unit being configured to: project the first image under a first condition; project the second image under a second condition; and project the first image and the second image under a third condition that is a condition between the first and second conditions. This configuration makes it possible to switch between displaying the first image and the second image under a plurality of different conditions, or to display the first image and the second image in an overlapping manner, thereby improving the visibility of a plurality of images viewed by the passenger as virtual images.

[0056] (2) The image projection device according to item (1), wherein the first condition is that the moving speed of the moving object is less than a first threshold, the second condition is that the moving speed is equal to or greater than a second threshold that is higher than the first threshold, and the third condition is that the moving speed is equal to or greater than the first threshold but less than the second threshold. According to the above configuration, visibility can be improved by changing the display mode of the first image and the second image depending on the moving speed of the moving object. Furthermore, since the first image and the second image are displayed overlapping each other when switching between the display of the first image and the second image depending on the moving speed, the sense of discomfort felt by the occupant can be reduced.

[0057] (3) The image projection device according to item (1), wherein the first condition is when the moving object is traveling on an ordinary road, the second condition is when the moving object is traveling on an expressway, and the third condition is when the moving object is entering the expressway from an ordinary road. According to the above configuration, visibility can be improved by changing the display mode of the first image and the second image depending on whether the moving object is traveling on an ordinary road or an expressway. Furthermore, when entering the expressway from an ordinary road, the first image and the second image are displayed overlapping each other, thereby reducing the sense of discomfort felt by the occupant.

[0058] (4) The image projection device according to item (2) or (3), wherein the control unit, under the third condition, when the moving object is accelerating, reduces the luminance of the first image and increases the luminance of the second image. With this configuration, it is possible to further reduce the sense of discomfort felt by an occupant when the display switches from the first image to the second image during acceleration of the moving object.

[0059] (5) The image projection device according to any one of items (1) to (4), wherein the second image is an image projected higher than the first image, and the control unit moves at least a portion of the first image and at least a portion of the second image upward. According to the above configuration, when the display is switched from the first image to the second image displayed higher than the first image, at least a portion of the first image and at least a portion of the second image are projected so as to move upward, thereby making it possible to naturally guide the line of sight of an occupant from the first image to the second image, particularly when a moving object is accelerating.

[0060] (6) The image projection device according to (4) or (5), wherein the control unit gradually makes at least a portion of the first image invisible from an upper region thereof. With this configuration, it is possible to more naturally guide the line of sight of the occupant from the first image to the second image.

[0061] (7) The image projection device according to item (2) or (3), wherein the control unit increases the luminance of the first image and decreases the luminance of the second image when the moving object is decelerating under the third condition. This configuration further reduces the sense of discomfort felt by an occupant when the display switches from the second image to the first image when the moving object is decelerating.

[0062] (8) The image projection device according to any one of items (1) to (3) and (7), wherein the second image is an image projected above the first image, and the control unit moves at least a portion of the first image and at least a portion of the second image downward. According to the above configuration, when the display is switched from the second image to the first image displayed below the second image, at least a portion of the first image and at least a portion of the second image are projected so as to move downward, thereby making it possible to naturally guide the line of sight of an occupant from the second image to the first image, particularly when decelerating a moving object.

[0063] (9) The image projection device according to (7) or (8), wherein the control unit gradually displays at least a portion of the first image from a lower region of the first image. With this configuration, it is possible to more naturally guide the line of sight of the occupant from the second image to the first image.

[0064] (10) An image projection device that allows a passenger of a moving body to view an image as a virtual image includes a control unit configured to switch between a first image projected at a first position and a second image projected at a second position different from the first position based on the moving speed of the moving body, wherein the control unit differentiates the moving speed of the moving body when switching from the first image to the second image from the moving speed when switching from the second image to the first image. According to the above configuration, by differentiating the threshold moving speed when the second image is projected instead of the first image and when the first image is projected instead of the second image, a predetermined image can be displayed by tracking the line of sight of the passenger. This can improve the visibility of multiple images viewed by the passenger as virtual images.

[0065] (11) The image projection device according to item (10), wherein the control unit projects the second image in place of the first image when the moving object accelerates, and projects the first image in place of the second image when the moving object decelerates. According to the above configuration, by differentiating the speed threshold for image switching during acceleration and the speed threshold for image switching during deceleration, it is possible to reduce discomfort felt by the occupant.

[0066] (12) The image projection device according to item (11), wherein the control unit sets a moving speed of the moving object when switching from the first image to the second image higher than a moving speed of the moving object when switching from the second image to the first image. According to the above configuration, by setting a speed threshold for image switching during acceleration higher than a speed threshold for image switching during deceleration, it is possible to switch between the display of the first image and the second image in accordance with the movement of the line of sight of the occupant, thereby further reducing the sense of discomfort felt by the occupant.

[0067] (13) The image projection device according to any one of items (10) to (12), wherein the second image is an image projected higher than the first image, and the control unit moves at least a portion of the first image and at least a portion of the second image upward when switching from the first image to the second image. According to the above configuration, when switching from the first image to the second image displayed higher than the first image, at least a portion of the first image and at least a portion of the second image are projected to move upward, thereby making it possible to naturally guide the line of sight of an occupant from the first image to the second image, particularly when a moving object is accelerating.

[0068] (14) The image projection device according to any one of items (10) to (13), wherein the second image is an image projected above the first image, and the control unit, when switching from the second image to the first image, moves at least a portion of the first image and at least a portion of the second image downward. According to the above configuration, when switching from the second image to the first image displayed below the second image, at least a portion of the first image and at least a portion of the second image are projected to move downward, thereby making it possible to naturally guide the line of sight of an occupant from the second image to the first image, particularly when decelerating a moving object.

[0069] This application is based on Japanese Patent Application No. 2024-1120, filed on January 9, 2024, the contents of which are incorporated herein by reference.

Claims

1. An image projection device that allows an occupant of a moving body to visually recognize an image as a virtual image, comprising a control unit configured to switch between a first image projected at a first position and a second image projected at a second position different from the first position based on the moving speed of the moving body, wherein the control unit makes the moving speed of the moving body when switching from the first image to the second image different from the moving speed of the moving body when switching from the second image to the first image.

2. The image projection device according to claim 1, wherein the control unit projects the second image instead of the first image when the moving body accelerates, and projects the first image instead of the second image when the moving body decelerates.

3. The image projection device according to claim 2, wherein the control unit sets the moving speed of the moving body when switching from the first image to the second image to be higher than the moving speed of the moving body when switching from the second image to the first image.

4. The second image is an image projected above the first image, and the control unit moves at least a part of the first image and at least a part of the second image upward when switching from the first image to the second image. The image projection device according to claim 3.

5. The second image is an image projected above the first image, and the control unit moves at least a part of the first image and at least a part of the second image downward when switching from the second image to the first image. The image projection device according to claim 3.

Images