JP2023136362A - Image projection device and image projection method - Google Patents

Abstract

To provide an image projection device and an image projection method suppressing a sense of incongruity when visually recognizing a front display image even if a preceding vehicle approaches.SOLUTION: An image projection device (10) projecting a projection image to a wind shield (16) for displaying virtual images (17 and 18), is equipped with an image irradiating portion (11) that irradiates the projection image, optical portions (12, 13, 14, and 15) that irradiates the projection image to the wind shield (16) as image light, distance measuring means (20) that detects the overlapping of the virtual images (17 and 18) on a preceding vehicle, and a control portion (30) that controls a projection position of the projection image so as to avoid the overlapping of the virtual images (17 and 18) and the preceding vehicle, on the basis of a degree of the overlapping.SELECTED DRAWING: Figure 1

Description

The present invention relates to an image projection device and an image projection method.

2. Description of the Related Art Conventionally, an instrument panel that displays illuminated icons has been used as a device for displaying various information in a vehicle. Additionally, as the amount of information to be displayed increases, it has also been proposed to embed an image display device in the instrument panel or to configure the entire instrument panel with an image display device.

However, since the instrument panel is located below the vehicle's windshield, in order for the driver to see the information displayed on the instrument panel, the driver must move his/her line of sight downwards while driving. Therefore, it is undesirable. Therefore, a head-up display (hereinafter referred to as HUD) that projects an image onto the windshield so that the driver can read information when visually checking the front of the vehicle has also been proposed (for example, Patent Document 1 , 2).

JP2019-119248A JP 2019-119262 Publication

In a vehicle equipped with a HUD, a driver visually recognizes a virtual image displayed in front of the vehicle (hereinafter referred to as a "front display image"). The display position of the forward display image in the vertical direction is normally set assuming a state where there is no preceding vehicle. Therefore, when a preceding vehicle approaches the host vehicle on the road, the forward display image overlaps with the preceding vehicle, making it difficult to visually recognize the forward display image, and the driver may feel uncomfortable. From the viewpoint of safety, it is preferable to eliminate such discomfort as much as possible.

SUMMARY OF THE INVENTION The present invention has been made in view of the above conventional problems, and provides an image projection device and an image projection method that suppress discomfort when viewing a front display image even when a preceding vehicle approaches. The purpose is to provide

In order to solve the above problems, an 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 irradiation unit that irradiates the projection image; an optical section that irradiates the display section with the projected image as image light; a detection section that detects an overlap between the virtual image and the preceding vehicle; and a detecting section that detects the overlap between the virtual image and the preceding vehicle based on the degree of overlap. The present invention is characterized by comprising a control unit that controls the projection position of the projection image so as to avoid overlapping.

Such an image projection device of the present invention includes an image irradiation unit that irradiates the projected image, an optical unit that irradiates the projected image as image light to a display unit that displays the virtual image, and an overlap between the virtual image and the preceding vehicle. The control unit controls the projection position of the projected image based on the degree of overlap so as to avoid overlap between the virtual image and the preceding vehicle. As a result, when the driver visually recognizes the road ahead, the overlap between the virtual image and the preceding vehicle is eliminated. This makes it possible to suppress the sense of discomfort when viewing the forward display image even when the preceding vehicle approaches.

Further, in one aspect of the present invention, the control unit controls the projection position of the projected image so as to move the virtual image downward to avoid overlapping the virtual image and the preceding vehicle. .

Further, in one aspect of the present invention, at night, the control unit allows the virtual image to overlap with the preceding vehicle and moves the virtual image above the taillight of the preceding vehicle.

Further, in one aspect of the present invention, the detection unit is a distance measuring unit that measures a distance to the preceding vehicle, and the control unit obtains the degree of overlap based on the distance to the preceding vehicle. It is characterized by

Further, one aspect of the present invention is characterized in that the detection section is an imaging means for capturing an image of the preceding vehicle, and the control section obtains the degree of overlap using an image of the preceding vehicle.

Further, in one aspect of the present invention, the control unit controls the projection position of the projection image while maintaining a constant relative positional relationship between the preceding vehicle and the virtual image.

Further, in one aspect of the present invention, the control unit may take a predetermined time to avoid overlapping the virtual image and the preceding vehicle when the preceding vehicle enters or exits from another lane. The method is characterized in that the projection position of the projection image is controlled.

Further, in one aspect of the present invention, the control unit determines whether it is necessary to avoid overlapping the virtual image and the preceding vehicle, taking into account the color relationship between the virtual image and the preceding vehicle. do.

Further, in one aspect of the present invention, the control unit controls the projection position of the projection image by a display position adjustment unit included in the image irradiation unit that adjusts the display position of the projection image. .

Further, in one aspect of the present invention, the control section controls the projection position of the projection image by a reflecting means included in the optical section and whose angle with respect to the projection image can be adjusted.

In order to solve the above problems, an image projection method of the present invention is an image projection device that projects a projection image onto a display section for displaying a virtual image, comprising: an image irradiation section that irradiates the projection image; An image projection method using an image projection device including an optical section that irradiates the projected image as image light onto a display section, and a detection section that detects an overlap between the virtual image and a preceding vehicle, the method comprising: The present invention is characterized in that the projection position of the projected image is controlled based on the degree of overlap of the virtual image and the preceding vehicle.

According to the present invention, it is possible to provide an image projection device and an image projection method in which discomfort when viewing a front display image is suppressed even when a preceding vehicle approaches.

FIG. 1 is a block diagram showing an example of the configuration of an image projection device according to a first embodiment. FIG. 3 is a schematic diagram showing an example of a configuration of a display area of an image irradiation unit according to the first embodiment. 2 is a flowchart showing the flow of processing of a display position adjustment program executed by the image projection device according to the first embodiment. FIG. 3 is a schematic diagram showing a method of calculating an adjusted depression angle in the image projection device according to the first embodiment. (a) to (c) are schematic diagrams showing the operation of the image projection device according to the first embodiment. It is a block diagram showing an example of composition of an image projection device concerning a 5th embodiment.

Embodiments of the present invention will be described in detail below with reference to the drawings. Identical or equivalent components, members, and processes shown in each drawing are designated by the same reference numerals, and redundant explanations will be omitted as appropriate. In the following description, an example will be described in which the image projection device according to the present invention is applied to a HUD mounted on a vehicle or the like.

(First embodiment)
An image projection device and an image projection method according to this embodiment will be described with reference to FIGS. 1 to 5. FIG. 1 is a block diagram showing an example of the configuration of an image projection device 10 according to this embodiment. The main body of the image projection device 10 is placed, for example, at the bottom of a dashboard of a vehicle. The image projection device 10 is an example of an image projection device that employs an image projection method capable of projecting two front display images on one screen. That is, the image projection device 10 displays a far image that is formed as a virtual image relatively far in front of the vehicle, and a near image that is formed as a virtual image relatively near in front of the vehicle. is possible. However, the application is not limited to this, and may be applied to an image projection device that projects three or more front display images on one screen, or an image projection device that projects one front display image on one screen, or an image projection device that projects three or more front display images on one screen. The present invention may be applied to an image projection device that projects a plurality of front display images.

As shown in FIG. 1, the image projection device 10 according to the present embodiment includes an image irradiation section 11, a reflecting mirror 12, a free-form surface mirror 13, a light branching section 14, a free-form surface mirror 15, a distance measuring means 20, an imaging means 21, and a control section 30. FIG. 1 also shows a windshield 16 onto which a projected image from the image projection device 10 is irradiated. Note that the "windshield 16" is an example of the "display section" according to the present invention. Moreover, the "reflector 12," the "free-form surface mirror 13," the "light branching section 14," and the "free-form surface mirror 15" are examples of the "optical section" according to the present invention.

The image irradiation unit 11 irradiates the front of the vehicle with an image for forming a virtual distant image or a near image. The image irradiation unit 11 includes, for example, a liquid crystal panel, an organic EL panel, a DMD (Digital Micro Mirror Device), and the like. The image irradiation unit 11 is divided into a far display area that displays an image for forming a far image and a near display area that displays an image for forming a near image. In FIG. 1, the optical path of the far image light emitted from the far display area is shown by a broken line, and the optical path of the near image light emitted from the near display area is shown by a dashed line.

The image projection device 10 is configured such that a far-field image (virtual image 18) displayed in front of the vehicle can be moved up and down (vertically). Therefore, the configuration is such that the position of the image displayed in the far display area of the image irradiation unit 11 can be changed. By moving the image displayed in the far display area, the projection position of the far image light from the image irradiation unit 11 onto the windshield 16 is adjusted, and as a result, the vertical direction of the far image is adjusted.

With reference to FIG. 2, movement of the display image in the far display area will be described in more detail. FIG. 2 is a schematic diagram showing a display area 40 in which an image is displayed by the image irradiation unit 11. The display area 40 is the entire area in which images can be displayed as a display. The display area 40 is provided with a far display area 41 that displays a far image formed at a far distance, and a near display area 43 that displays a near image formed at a near distance. In the image projection device 10, far-field image light that illuminates the far-field image displayed in the far-field display area 41 is formed into a far-field virtual image 18 via the light branching section 14 and the like. Furthermore, the near image light that illuminates the near image displayed in the near display area 43 is focused as a virtual image 17 in the near area via the reflecting mirror 12 and the like.

A margin area 42 is provided around the far display area 41, and the image displayed in the far display area 41 can be moved within the margin area 42 in directions D1 and D2 shown by arrows in FIG. . As a result, the irradiation position of the far-field image light onto the windshield 16 is adjusted, and as a result, the vertical position of the far-field image is adjusted.

As shown in FIG. 1, the image irradiation unit 11 is connected to the control unit 30, and the control unit 30 controls the movement of the position of the image displayed in the far display area, that is, the vertical movement of the far image. In this embodiment, the "distant display area 41" in which the position of the displayed image can be changed is an example of the "display position adjustment means" according to the present invention.

Note that in this embodiment, the image displayed in the far display area is configured so that the far image can be moved up and down, but if the discomfort of the near image becomes a problem, it is possible to move the far image in the near display area. It may be configured such that the near image can be moved in the vertical direction by moving the displayed image. Alternatively, the configuration may be such that both the far image and the near image can be moved in the vertical direction.

The light branching unit 14 is a member that branches distant image light irradiated from a far display area, and is composed of a prism as an example. As shown in FIG. 1, the far-field image light passes through the light branching section 14, is reflected by the free-form mirror 15, the free-form mirror 13, and the windshield 16, and reaches the driver's viewpoint 52. As a result, a virtual image 18 (distant image) is formed in a relatively far distance in front of the vehicle. The display position of the distant image is, for example, about 15 m in front of the vehicle. In FIG. 1, "driving support display" is illustrated as an example of the content of the distant image.

On the other hand, as shown in FIG. 1, the near-field image light is emitted from the near-field display area, is reflected by the reflecting mirror 12, the free-form mirror 13, and the windshield 16, and reaches the driver's viewpoint 52. As a result, a virtual image 17 (near image) is formed relatively near the front of the vehicle. The display position of the near image is, for example, about 3 m in front of the vehicle. In FIG. 1, "vehicle speed display, etc." is illustrated as an example of the content of the near image.

With the above configuration, in the image projection device 10, the virtual image 18 is projected in the distance several degrees downward from the horizontal direction, and the driver's line of sight movement for viewing the driving support information can be reduced. Further, a virtual image 17 is projected further downward and near, and by moving the line of sight, the vehicle speed display etc. can be clearly viewed.

The distance measuring means 20 is a part that measures distances to objects around the vehicle, and is configured by, for example, LiDAR (Light Detection and Ranging), radar, or the like. In this embodiment, the distance measuring means 20 is mainly used to measure the distance between the preceding vehicle traveling ahead and the own vehicle (hereinafter referred to as "inter-vehicle distance"). The measured distance is sent to the control section 30. Note that the "distance measuring means 20" is an example of the "detection section" according to the present invention.

The image capturing means 21 is a part that captures an image of the front of the vehicle, and is constituted by, for example, an on-vehicle camera. The camera may be a monocular camera or a stereo camera. A stereo camera can also serve as a distance measuring device. In this embodiment, the imaging means 21 is mainly used to detect an overlap between a distant image and a preceding vehicle. The imaging means 21 is connected to the control section 30, and the image taken by the imaging means 21 is sent to the control section 30 and subjected to image processing. Note that the imaging means 21 is not used in this embodiment, but is used in the second embodiment described below.

The control unit 30 performs overall control of the entire image projection device 10, and also executes a display position adjustment program to be described later. The control unit 30 is configured to include a CPU, ROM, RAM, etc., which are not shown. Note that the control unit 30 may be an ECU (Engine Control Unit) of a vehicle in which the image projection device 10 is mounted.

Here, as described above, when a preceding vehicle approaches the host vehicle on the road, the distant image overlaps with the preceding vehicle, making it difficult to visually recognize the distant image, and the driver may feel uncomfortable. Therefore, in this embodiment, the overlapping between the distant image and the preceding vehicle is estimated, and based on the estimation result, the distant image is moved downward to avoid the overlapping between the distant image and the preceding vehicle. More specifically, the distance to the preceding vehicle, that is, the inter-vehicle distance, is measured by the distance measuring means 20, and when the inter-vehicle distance satisfies a predetermined condition, an adjustment depression angle is calculated to adjust the depression angle of the distant image. The position of the image displayed in the far display area of the image irradiation unit 11 is adjusted. As a result, the projection position of the far image light from the image irradiation unit 11 onto the windshield 16 is adjusted, and the vertical position of the far image is adjusted. Note that in this embodiment, the present invention is applied to far images, so in the following description, "far images" will be referred to as "front display images."

A procedure for adjusting the display position of the front display image executed by the image projection device 10 according to the present embodiment will be described with reference to FIG. 3. FIG. 3 is a flowchart showing the process flow of a display position adjustment program, which shows the procedure of display position adjustment processing executed by the control unit 30 of the image projection device 10. This display position adjustment program is stored in a storage means such as a ROM (not shown), and is read out by the CPU, expanded to a RAM, etc., and executed.

In step S10, the control unit 30 waits for detection of a preceding vehicle. If the determination in step S10 is affirmative, the process moves to step S11.

In step S11, it is determined whether the angle of depression of the front display image needs to be adjusted.

With reference to FIG. 4, an example of a method of determining whether or not adjustment of the depression angle is necessary, which is executed in the image projection apparatus 10 according to the present embodiment, will be described. In FIG. 4, a vehicle 51 as the own vehicle traveling on a road 50 and a preceding vehicle 54 preceding the vehicle 51 are illustrated. The symbol hr indicates a horizontal line extended from the driver's viewpoint 52. In this embodiment, when the front display image and the preceding vehicle 54 overlap, the destination of the front display image is assumed to be below the lower end of the rear license plate 55. Assuming that the distance between vehicles is L, the distance from the road surface of the road 50 to the horizontal line hr is H, and the distance from the road surface to the lower end of the rear license plate 55 is h, the depression angle θ shown in FIG. 4 is generally expressed as follows. It can be calculated using (Formula 1).
θ=arctan((HH)/L)... (Formula 1)

On the other hand, the angle of depression measured from the horizontal line hr when the upper end of the front display image in the standard display position overlaps the lower end of the rear license plate 55 is defined as the minimum angle of depression θmin. If the inter-vehicle distance between the vehicle 51 and the preceding vehicle 54 measured by the distance measuring means 20 at this time is the maximum inter-vehicle distance Lmax, the minimum depression angle θmin is calculated from (Equation 1) by (Equation 2) shown below.
θmin=arctan((HH)/Lmax)... (Formula 2)

As described above, in the image projection device 10, the position below the lower end of the rear license plate 55 is assumed as the position to which the front display image is moved when it overlaps with the preceding vehicle 54. In other words, it is assumed that at this position, the driver can view the forward display image without being obstructed by the preceding vehicle 54. Of course, the minimum depression angle θmin is not limited to the above concept, and may be set assuming other locations of the preceding vehicle 54. The distance H from the road surface to the horizontal line hr can be set in advance by adopting a standard value for the position of the viewpoint 52. However, the setting is not limited to this, and may be set for each driver. On the other hand, the distance h from the road surface to the license plate can also be set in advance by adopting a standard value. However, the setting is not limited to this, and may be set for each vehicle. In this embodiment, H and h are set in advance, and (HH) is treated as a constant.

Based on the above assumptions, the depression angle θ of the lower end of the rear license plate 55 of the preceding vehicle 54 can generally be calculated from the above (Formula 1) using the inter-vehicle distance L. In this embodiment, in step S11, it is determined that the depression angle needs to be adjusted when θ>θmin. Since the depression angle θ and the inter-vehicle distance L have a 1:1 correspondence, it may be determined that the depression angle needs to be adjusted when L<Lmax.

Referring again to FIG. 3, the adjusted depression angle θa is obtained in step S12. The adjusted depression angle θa is basically the depression angle θ calculated by substituting the inter-vehicle distance L measured by the distance measuring means 20 into (Equation 1). However, the present invention is not limited to this, and the calculated θ may be subjected to some kind of correction, such as, for example, multiplied by a coefficient that takes into account safety.

In step S13, it is determined whether the adjusted depression angle θa obtained in step S12 is within the depression angle adjustment range. If the determination is affirmative, the process moves to step S14, and if the determination is negative, the process moves to step S15.

Here, in this embodiment, the depression angle adjustment is started when the depression angle θ becomes θ>θmin, and the depression angle θ is increased as the inter-vehicle distance L becomes smaller than the maximum inter-vehicle distance Lmax. The maximum depression angle θmax, which is the upper limit value of the depression angle θ at this time, may be set in advance. Step S13 is a process when this maximum depression angle θmax is determined. The maximum depression angle θmax may be set, for example, within a range in which the far display area 41 can move within the margin area 42, or may be set within the tilt angle adjustment range of the free-form mirror 13 in the fifth embodiment described below. Good too. Alternatively, it may be set within the visible range of the forward display image by the driver. When the maximum depression angle θmax is set, the minimum inter-vehicle distance Lmin is inevitably set.

In step S14, the projection position adjustment section, that is, the image irradiation section 11 in this embodiment, is adjusted. More specifically, the image displayed in the far display area 41 of the display area 40 is moved based on the adjusted depression angle θa, and the projection position of the far image light emitted from the image irradiation unit 11 onto the windshield 16 is adjusted. By doing this, the irradiation position of the distant image is adjusted.

On the other hand, in step S15, the front display image, that is, the distant image is turned off. This is because if the forward display image continues to be displayed while the depression angle adjustment range is exceeded, there is a high probability that the forward display image will overlap with the preceding vehicle 54.

In step S16, it is determined whether an end instruction has been given. If the determination is negative, the process moves to step S10 to continue detecting the preceding vehicle. That is, in this embodiment, since the preceding vehicle is constantly detected, the relative positional relationship between the preceding vehicle 54 and the display position of the forward display image is continuously and smoothly adjusted. On the other hand, if the determination is affirmative, this display position adjustment program is ended. The instruction to end is, for example, turning off the power of the image projection device 10.

With reference to FIG. 5, the functions and effects of the image projection device 10 according to this embodiment will be described in more detail. FIG. 5(a) shows a state where the preceding vehicle 54 is far away and the front display image (virtual image 18, distant image) is located sufficiently below the preceding vehicle 54, that is, the depression angle θ is θ≦θmin (the inter-vehicle distance L is L ≧Lmax).

Next, when the vehicle 51 approaches the preceding vehicle 54 and the depression angle θ becomes θ>θmin (the inter-vehicle distance L is L<Lmax), the front display image (virtual image 18) changes to the preceding vehicle 54 as shown in FIG. 5(b). This overlaps, making it difficult for the driver to visually recognize the forward display image (virtual image 18).

FIG. 5(c) shows a state in which the forward display image (virtual image 18) has been moved to the lower part of the preceding vehicle 54 as a result of the execution of the display position adjustment process, and the difficulty in visual recognition has been resolved.

Note that although the color of the preceding vehicle 54 was not considered in the above description, the color relationship between the preceding vehicle 54 and the forward display image may be used as one of the criteria for determining overlap. That is, for example, if the color of the front display image is a bright color and the color of the preceding vehicle 54 is a dark color such as black, the degree of difficulty in visual recognition for the driver is low, so the front display image is intentionally moved. Not even. In such a case, it may be determined that there is no need to move the front display image. More specifically, step S11 of the flowchart shown in FIG. 3 may include a comparison between the color of the preceding vehicle 54 acquired by the imaging means 21 or the like and the color of the forward display image.

As described in detail above, according to the image projection device and the image projection method according to the present embodiment, even when a preceding vehicle approaches, an image can be projected that suppresses the sense of discomfort when viewing the forward display image. It becomes possible to provide a device and an image projection method.

(Second embodiment)
An image projection device 10A and an image projection method according to the present embodiment will be described with reference to FIGS. 1 to 3 and 5. This embodiment is a modification of the first embodiment described above, in which the method for detecting a preceding vehicle and the method for detecting an overlap between the forward display image and the preceding vehicle are changed. That is, in this embodiment, a preceding vehicle is detected using the imaging means 21 shown in FIG. 1, an overlap between the forward display image and the preceding vehicle is detected, and an overlap between the forward display image and the preceding vehicle is avoided. The configuration of the image projection device according to this embodiment is the same as that of the first embodiment except for the imaging means 21, so detailed explanation will be omitted. However, this embodiment is also applicable to the fifth embodiment described below. In the image projection device 10A, the forward display image to be avoided from overlapping with the preceding vehicle is a distant image (virtual image 18), as in the image projection device 10. Note that the "imaging means 21" is an example of the "detecting section" according to the present invention.

The imaging means 21 is connected to the control unit 30 and, under the control of the control unit 30, acquires an image in front of the own vehicle, for example, an image as illustrated in FIG. sending. The control unit 30 processes the surrounding image and recognizes, for example, the external shape of the preceding vehicle. On the other hand, the control unit 30 knows the display position of the forward display image based on the angle of depression, for example. The image irradiation unit 11 of the image projection device 10A according to this embodiment also has the configuration shown in FIG. 2, and allows movement of the far display area 41, that is, vertical adjustment of the front display image.

The basic procedure of the image projection method according to this embodiment is the same as that shown in FIG. 3. That is, the display position adjustment process shown in FIG. 3 is also executed in the image projection device 10A. The display position adjustment process executed by the control unit 30 according to the present embodiment will be described below with reference to FIG. 3.

The process waits until a preceding vehicle is detected in step S10, and if an affirmative determination is made, the process moves to step S11.

In step S11, it is determined whether the angle of depression of the display position of the front display image needs to be adjusted. This determination is made, for example, by image recognition, and for example, when the preceding vehicle 54 and the virtual image 18 overlap as shown in FIG. 5(b), it is determined that the angle of depression needs to be adjusted. Note that the determination that the angle of depression adjustment is necessary is not limited to the case where the preceding vehicle 54 and the virtual image 18 completely overlap, but is determined that the angle of depression adjustment is necessary when the virtual image 18 overlaps by a predetermined percentage, for example, 50% or more. It's okay.

In step S12, the adjusted depression angle, that is, the depression angle necessary to avoid overlapping is obtained. The adjustment angle of depression is performed by calculating, for example, the angle of depression when the virtual image 18 is located below the preceding vehicle 54 by image recognition.

The processing from step S13 onward is the same as that of the image projection device 10 according to the first embodiment, so the explanation will be omitted. In this embodiment as well, steps S10 to S16 are looped unless an end instruction is given in step S16, so the relative positional relationship between the preceding vehicle 54 and the display position of the forward display image is adjusted continuously and smoothly.

As described above, the image projection device and the image projection method according to the present embodiment suppress the discomfort when viewing the forward display image even when a preceding vehicle approaches, and It becomes possible to provide an image projection method.

(Third embodiment)
The image projection device and the image projection method according to this embodiment are such that a predetermined display position adjustment process is executed when a vehicle travels at night. The configuration of the image projection device according to this embodiment is the same as that in FIG. 1, so the drawing is omitted. The image projection device and image projection method according to this embodiment can be applied to any of the first embodiment and second embodiment described above, or the fifth embodiment described below.

Here, as mentioned above, if the color of the front display image is a bright color and the color of the preceding vehicle 54 is a dark color such as black, it will be less difficult for the driver to visually recognize There is no need to move the displayed image. Considering this point further, at night, the rear of the preceding vehicle 54 is in a dark state except for lights such as taillights (rear combination lamps). Therefore, in the display position adjustment process of the front display image, although the front display image is basically moved downward when it overlaps with the preceding vehicle 54, it may be moved upward only at night. . In this case, it is necessary to avoid overlapping with the taillight, so it may be moved above the taillight. Determination that it is nighttime and detection of taillights are performed, for example, by the control unit 30 processing an image captured by the imaging means 21. Of course, the determination of whether it is nighttime may be made using a clock.

The specific process of this embodiment includes, for example, a process for determining whether it is night time and a process for detecting a taillight in step S11 in the flow of the display position adjustment process shown in FIG. 3. Then, in step S12, the angle of depression for moving upward while avoiding taillights etc. may be calculated. In this embodiment as well, steps S10 to S16 are looped unless an end instruction is given in step S16, so the relative positional relationship between the preceding vehicle 54 and the display position of the forward display image is adjusted continuously and smoothly.

As described above, the image projection device and the image projection method according to the present embodiment suppress the discomfort when viewing the forward display image even when a preceding vehicle approaches, and It becomes possible to provide an image projection method. Furthermore, according to the image projection device and the image projection method according to the present embodiment, the forward display image is moved upward as well as downward, so that the display position of the forward display image can be set to be more easily recognized by the driver. I can do it.

(Fourth embodiment)
The image projection device and image projection method according to the present embodiment are configured to execute a predetermined display position adjustment process when a preceding vehicle suddenly enters or leaves the vehicle. The configuration of the image projection device according to this embodiment is the same as that in FIG. 1, so the drawing is omitted. The image projection device and image projection method according to this embodiment are applicable to any of the first embodiment and second embodiment described above, or the fifth embodiment described below.

In the display position adjustment processing according to each of the embodiments described above, the change of course of the preceding vehicle 54 or the host vehicle is not taken into account. However, on an actual road, the host vehicle may change lanes, or the preceding vehicle 54 may suddenly enter or exit the vehicle. In such a case, it is expected that the display position of the forward display image (in this embodiment, the distant image) will change rapidly as the host vehicle or the preceding vehicle 54 changes course. Such sudden movement of the forward display image may make the driver feel uncomfortable, so it is better to avoid it as much as possible. Therefore, in this embodiment, the display position of the forward display image is configured not to change suddenly when the host vehicle changes lanes or a preceding vehicle suddenly enters or leaves the vehicle.

First, a case where the preceding vehicle 54 suddenly approaches will be explained according to the flow shown in FIG. 3. The determination of sudden entry of the preceding vehicle 54 is included in step S10, for example. More specifically, assume that the distance measuring means 20 suddenly detects a preceding vehicle 54 located at a small inter-vehicle distance L. When the preceding vehicle 54 suddenly enters, the arrangement relationship between the preceding vehicle 54 and the forward display image (virtual image 18) shown in FIG. 5(b) may suddenly appear. At this time, if the display position adjustment process is executed according to the flow shown in FIG. 3, the sudden intrusion of the preceding vehicle 54 and the rapid movement of the forward display image may overlap, making the driver feel uncomfortable.

Therefore, in this embodiment, it was decided to move the display position of the front display image (virtual image 18) from FIG. 5(b) to FIG. 5(c) over a predetermined period of time. More specifically, the angle of depression is adjusted in step S14 of the flow shown in FIG. 3 over a predetermined period of time. The predetermined time varies depending on the position of the preceding vehicle 54, the display position (depression angle) of the forward display image, etc., but is approximately several seconds. This can suppress the driver's discomfort caused by the movement of the preceding vehicle 54 and the forward display image.

Next, a case where the preceding vehicle 54 suddenly leaves will be explained according to the flow shown in FIG. 3. The determination of sudden exit of the preceding vehicle 54 is included in step S10, for example. More specifically, for example, a case is assumed in which the distance measuring means 20 suddenly detects that the distance to the preceding vehicle 54 cannot be measured (or the distance has become longer than a certain value). When the preceding vehicle 54 suddenly leaves, in the arrangement relationship between the preceding vehicle 54 and the forward display image (virtual image 18) shown in FIG. 5(c), only the forward display image is suddenly left behind. In such a case, it can be said that even if normal display position adjustment processing is performed, the driver will feel less discomfort than if the preceding vehicle 54 suddenly approached. However, for safety reasons, the forward display image may be moved over a predetermined period of time in this case as well. More specifically, the angle of depression is adjusted in step S14 of the flow shown in FIG. 3 over a predetermined period of time. Since the adjusted depression angle in this case is the depression angle of the standard display position of the distant image, that is, the minimum depression angle θmin, the depression angle of the virtual image 18 shown in FIG. 5(c) gradually moves toward the minimum depression angle θmin. The predetermined time varies depending on the position of the preceding vehicle 54, the display position (depression angle) of the forward display image, etc., but is approximately several seconds. This can suppress the driver's discomfort caused by the movement of the preceding vehicle 54 and the forward display image.

As described above, the image projection device and the image projection method according to the present embodiment suppress the discomfort when viewing the forward display image even when a preceding vehicle approaches, and It becomes possible to provide an image projection method. According to the image projection device and the image projection method according to the present embodiment, it is possible to suppress the sense of discomfort especially when a preceding vehicle suddenly enters or exits.

(Fifth embodiment)
With reference to FIG. 6, an image projection device and an image projection method according to this embodiment will be described. The image projection device 10B according to the present embodiment is a modification of the image projection device 10 according to the embodiment described above, except that the projection position adjustment section is changed. Therefore, the same components as in FIG. 1 are denoted by the same reference numerals, and detailed description thereof will be omitted.

As shown in FIG. 6, in the image projection device 10B, a free-form mirror 13 is connected to the control section 30 instead of the image irradiation section 11. The "free-form mirror 13" corresponds to the "projection position adjustment section" shown in step S14 in FIG. 3. The free-form mirror 13 is provided with a mechanism (not shown) for adjusting the tilt angle, and by adjusting the tilt angle, the projection position of the distant image light from the image irradiation section 11 onto the windshield 16 is adjusted. As a result, the vertical direction of the distant image is adjusted. The specific method and procedure for adjusting the display position of the front display image are as shown in FIGS. 3 and 5. Note that the free-form mirror 13 is an example of a "reflection means" according to the present invention.

Here, in the case of the image projection device 10B shown in FIG. 6, when the tilt angle of the free-form mirror 13 is adjusted, the near image also moves at the same time. However, since the display position of the near image is less sensitive to changes in the tilt angle than the display position of the front display image, this does not pose a problem in many cases. However, if it is desired to move only the front display image, the light branching section 14 or the free-form mirror 15 may be moved. Alternatively, separate free-form mirrors 13 may be provided for each of the far image light and the near image light.

As described above, the image projection device and the image projection method according to the present embodiment suppress the discomfort when viewing the forward display image even when a preceding vehicle approaches, and It becomes possible to provide an image projection method. In particular, according to the image projection device and the image projection method according to the present embodiment, the vertical movement range of the front display image can be increased compared to the first embodiment, and the display of the image irradiation unit 11 can be This has the advantage that there is no need to enlarge the area 40.

Note that in each of the above embodiments, the image projection device and the image projection method according to each embodiment have been individually described, but a plurality of embodiments may be combined. For example, the first embodiment and the fifth embodiment may be combined to enable both the movement of the front display image by the image irradiation unit 11 and the movement of the front display image by the free-form mirror 13. At that time, priority may be set between the movement of the front display image by the image irradiation unit 11 and the movement of the front display image by the free-form mirror 13. For example, the configuration may be such that priority is given to the movement of the front display image by the image irradiation unit 11, and the movement of the front display image by the free-form mirror 13 is applied to a range that exceeds the ability of the image irradiation unit 11.

Further, in each of the above embodiments, the display position adjustment program shown in FIG. 3 has been described by exemplifying a mode in which a preceding vehicle is always detected, but the present invention is not limited to this, and a mode in which the preceding vehicle is detected periodically or intermittently may be used. In the case of periodic detection, for example, a timer operation may be provided before step S10. Furthermore, in the case of intermittent acquisition, the control unit 30 may execute the display position adjustment program shown in FIG. 3 when necessary.

10... Image projection device 11... Image irradiation section 12... Reflection mirror 13... Free curved mirror 14... Light branching section 15... Free curved mirror 16... Windshields 17, 18... Virtual image 20... Distance measuring means 21... Imaging means 30... Control Section 40...Display area 41...Far display area 42...Margin area 43...Near display area 50...Runway 51...Vehicle 52...Viewpoint 54...Leading vehicle 55...Rear license plate D1, D2...Direction hr...Horizontal line H, h... Distance L...Distance between vehicles Lmin...Minimum distance between vehicles Lmax...Maximum distance between vehicles θ...Angle of depression θmin...Minimum angle of depression θmax...Maximum angle of depression

Claims (11)

An image projection device that projects a projection image onto a display unit for displaying a virtual image,
an image irradiation unit that irradiates the projected image;
an optical unit that irradiates the display unit with the projected image as image light;
a detection unit that detects an overlap between the virtual image and the preceding vehicle;
An image projection device comprising: a control unit that controls a projection position of the projection image based on the degree of overlap so as to avoid overlap between the virtual image and the preceding vehicle. The image projection device according to claim 1,
The image projection device is characterized in that the control unit controls the projection position of the projected image so as to move the virtual image downward to avoid overlapping the virtual image and the preceding vehicle. The image projection device according to claim 1,
In the case of nighttime, the image projection device is characterized in that the control unit allows the virtual image and the preceding vehicle to overlap and moves the virtual image above a tail light of the preceding vehicle. The image projection device according to any one of claims 1 to 3,
The detection unit is a distance measuring means for measuring a distance to the preceding vehicle,
The image projection device is characterized in that the control unit obtains the degree of overlap based on a distance from the preceding vehicle. The image projection device according to any one of claims 1 to 3,
The detection unit is an imaging means for imaging the preceding vehicle,
The image projection device is characterized in that the control unit obtains the degree of overlap using an image of the preceding vehicle. The image projection device according to any one of claims 1 to 5,
The image projection device is characterized in that the control unit controls a projection position of the projection image while maintaining a constant relative positional relationship between the preceding vehicle and the virtual image. The image projection device according to any one of claims 1 to 6,
The control unit controls the projection position of the projected image over a predetermined period of time when the preceding vehicle enters or exits from another lane, so as to avoid overlapping the virtual image and the preceding vehicle. An image projection device characterized by: The image projection device according to any one of claims 1 to 7,
The image projection device is characterized in that the control unit determines whether it is necessary to avoid overlapping the virtual image and the preceding vehicle, taking into account the color relationship between the virtual image and the preceding vehicle. The image projection device according to any one of claims 1 to 8,
The image projection apparatus is characterized in that the control unit controls the projection position of the projection image by a display position adjustment unit included in the image irradiation unit that adjusts the display position of the projection image. The image projection device according to any one of claims 1 to 8,
The image projection device is characterized in that the control section controls the projection position of the projection image by a reflecting means included in the optical section and whose angle with respect to the projection image can be adjusted. An image projection device that projects a projection image onto a display unit for displaying a virtual image, the image irradiation unit irradiating the projection image, and the optical unit irradiating the display unit with the projection image as image light. , and an image projection method using an image projection device including a detection unit that detects an overlap between the virtual image and the preceding vehicle,
An image projection method comprising: controlling a projection position of the projection image based on the degree of overlap so as to avoid overlap between the virtual image and the preceding vehicle.

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