Image projection apparatus and image projection method

Abstract

To provide an image projection device and image projection method, which improve visibility of an image by suppressing fluctuation of imaging position due to vehicle vibration while securing effective image display area.SOLUTION: An image projection device (100) for irradiating a display unit for displaying a virtual image with a projection image is provided, the image projection device (100) comprising an image irradiation unit (10) for irradiating a first image, a first optical unit (30) configured to irradiate the first image as first image light via the display unit in a viewing direction, a vibration sensing unit (50) for sensing vibration, and a first optical drive unit (70) configured to change an incident angle of the first image light with respect to the display unit according to vibration information.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] Conventionally, as a device for displaying various information in a vehicle, an instrument panel that lights up icons has been used. In addition, with the increase in the amount of information to be displayed, 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.

[0003] However, since the instrument panel is located below the front glass (windshield) of the vehicle, it is not preferable because the driver needs to move the line of sight downward during driving in order to visually recognize the information displayed on the instrument panel. Therefore, a head-up display (hereinafter referred to as HUD: Head Up Display) that projects an image onto the front glass so that the driver can read the information when visually recognizing the front of the vehicle has also been proposed (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In addition, in order to present more information, it has also been proposed to project a plurality of images onto the windshield using a driving assistance HUD device. However, in order to project a plurality of images as virtual images at different distances and form images, it is necessary to provide a plurality of image irradiation units and projection optical systems, and there is a problem that the degree of freedom in design is low in order to accommodate them in the instrument panel. Therefore, the applicant of the present application has proposed an image projection device that aims to save space by displaying a plurality of images in one image irradiation unit and branching the optical paths of each image by an optical branching unit such as a prism.

[0006] FIG. 6 is a schematic diagram showing a conventional image projection device for projecting a plurality of images on one screen. As shown in FIG. 6, the conventional image projection device includes an image irradiation unit 1, a reflecting mirror 2, a free-form surface mirror 3, an optical branching unit 4, a free-form surface mirror 5, and a windshield 6. In such an image projection device, a part of the light irradiated from the image irradiation unit 1 is branched by the optical branching unit 4, reflected by the free-form surface mirror 5, the free-form surface mirror 3, and the windshield 6, and reaches the driver's viewpoint, and a virtual image 8 is formed in the distance. Another part of the light irradiated from the image irradiation unit 1 is reflected by the reflecting mirror 2, the free-form surface mirror 3, and the windshield 6 and reaches the driver's viewpoint, and a virtual image 7 is formed nearby.

[0007] Therefore, in the conventional image projection device, the virtual image 8 is projected at a distance several degrees below the horizontal direction (about 15 m from the driver in FIG. 6), and the line-of-sight movement for the driver to visually recognize the driving assistance information can be reduced. In addition, the virtual image 7 is projected closer and further below (about 3 m from the driver in FIG. 6), and the vehicle speed display etc. can be visually recognized well by moving the line of sight. However, during the running of the vehicle, since the vehicle itself and the image projection device vibrate according to the running state and the road surface state, there is a problem that the imaging positions of the virtual images 7 and 8 are displaced due to the vibration and the visibility is reduced.

[0008] FIG. 7 is a schematic diagram showing a display area displayed by an image irradiation unit 1 in a conventional image projection device. In the image irradiation unit 1, the entire display area 1a indicates all areas where an image can be displayed. In the entire display area 1a, a near display area 1b for displaying a near image formed nearby and a far display area 1c for displaying a far image formed far away are provided. In the image projection device shown in FIG. 6, light irradiating the near image displayed in the near display area 1b is imaged as a virtual image 7 nearby via a reflecting mirror 2, and light irradiating the far image displayed in the far display area 1c is imaged as a virtual image 8 far away via an optical branching unit 4. However, when the vehicle is running, the vehicle and the image projection device vibrate, so that the imaging positions of the virtual images 7 and 8 vary with respect to the background, and a problem occurs in that the visibility of the image deteriorates.

[0009] In order to suppress such a change in the imaging positions of the virtual images 7 and 8 due to vibration during vehicle running, a method can be considered in which a sensor for detecting vibration of the vehicle is provided, and the image display position in the image irradiation unit 1 is corrected according to the detection result of the sensor. When the sensor detects vibration of the vehicle, the vibration direction and the displacement amount are calculated, and the display positions of the near display area 1b and the far display area 1c are changed within the margin areas 1d and 1e, respectively. Thereby, the displacement of the virtual images 7 and 8 due to vibration can be offset by the displacement within the margin areas 1d and 1e, and a change in the imaging positions of the near image and the far image can be suppressed.

[0010] However, in such a method of changing the display positions of the near display area 1b and the far display area 1c within the margin areas 1d and 1e, it is necessary to secure the margin areas 1d and 1e in order to cancel out the vibration within the entire display area 1a. For example, as shown in FIG. 7, when securing a displacement amount of about 15% above and below the near display area 1b and the far display area 1c, respectively, it means that the image size that can be displayed becomes 30% smaller. Therefore, the image size that can be imaged as the virtual images 7 and 8 cannot be increased, and a problem occurs in that the visibility of the near image and the far image displayed as the virtual images 7 and 8 deteriorates.

[0011] Therefore, the present invention has been made in view of the above-described conventional problems, and an image projection apparatus and an image projection method capable of improving the visibility of an image by suppressing fluctuations in the imaging position due to vehicle vibrations while securing an effective image display area are provided.

Means for Solving the Problems

[0012] In order to solve the above problems, an image projection apparatus of the present invention is an image projection apparatus that irradiates a projection image onto a display unit for displaying a virtual image, and includes a first image and a second image irradiation unit that irradiates, and a first optical unit that irradiates the first image as first image light in the viewpoint direction through the display unit. a second optical unit that irradiates the second image as second image light in the viewing direction through the display unit, and an optical branching unit that branches the first image light and the second image light; Based on vibration information , changing the angle of the optical branching unit with respect to the image irradiation unit, It is characterized by including a first optical drive unit that changes the incident angle of the first image light with respect to the display unit.

[0013] In such an image projection apparatus of the present invention, based on vibration information, a correction amount of the incident angle of the first image light with respect to the display unit is calculated, and the first optical drive unit is controlled according to the correction amount to correct the imaging position of the first image. Therefore, it is possible to improve the visibility of the image by suppressing fluctuations in the imaging position due to vehicle vibrations while securing an effective image display area.

[0014] Further, in one aspect of the present invention, it includes a vibration detection unit that detects vibrations and acquires the vibration information, and a correction control unit that calculates a correction amount of the incident angle based on the vibration information and controls the first optical drive unit according to the correction amount to correct the imaging position of the first image.

[0016] Further, in one aspect of the present invention, the imaging position of the virtual image is farther from the viewpoint position for the first image than for the second image.

[0018] Further, in one aspect of the present invention, the optical branching unit is a prism.

[0019] In addition, in one aspect of the present invention, a second optical driving unit is provided that changes the incident angle of the second image light with respect to the display unit based on the vibration information.

[0020] In addition, in one aspect of the present invention, the first optical driving unit changes the angle of any of the optical members constituting the first optical unit.

[0021] In order to solve the above problems, an image projection method of the present invention is an image projection method for irradiating a projection image onto a display unit for displaying a virtual image, the first image as first image light and the second image as second image light are branched by the optical branching unit and passed through the display unit an image irradiation step of irradiating in the viewpoint direction, a vibration detection step of acquiring vibration information, and based on the vibration information, changing the angle of the optical branching unit, a correction control step of changing the incident angle of the first image light with respect to the display unit to correct the imaging position of the first image.

Advantages of the Invention

[0022] In the present invention, it is possible to provide an image projection apparatus and an image projection method capable of suppressing fluctuations in the imaging position due to vibrations of a vehicle and improving the visibility of an image while securing an effective image display area.

Brief Description of the Drawings

[0023] [Fig. 1] It is a block diagram showing the configuration of an image projection apparatus 100 according to the first embodiment. [Fig. 2] It is a schematic diagram showing the configuration of an image projection apparatus 100 according to the first embodiment. [Fig. 3] It is a schematic diagram showing the display area of an image irradiated from an image irradiation unit 10 in the image projection apparatus 100 according to the first embodiment. [Fig. 4] It is a flowchart showing the steps of an image projection method according to the first embodiment. [Fig. 5] It is a schematic diagram showing the configuration of an image projection apparatus 110 according to the second embodiment. [Fig. 6] It is a schematic diagram showing a conventional image projection apparatus for projecting a plurality of images on one screen. [Fig. 7] It is a schematic diagram showing the display area of the image displayed by the image irradiation unit 1 in the conventional image projection device.

Embodiments for Carrying Out the Invention

[0024] (First Embodiment) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The same or equivalent components, members, and processes shown in each drawing are denoted by the same reference numerals, and repeated explanations will be omitted as appropriate. FIG. 1 is a block diagram showing the configuration of an image projection device 100 according to the present embodiment. As shown in FIG. 1, the image projection device 100 includes an image irradiation unit 10, an optical branching unit 20, a first optical unit 30, a second optical unit 40, a vibration detection unit 50, a correction control unit 60, and an optical drive unit 70. The light projected from the image projection device 100 is irradiated to the driver's viewpoint position through a windshield (display unit) not shown in the figure.

[0025] In addition, the image projection device 100 includes a control unit that is connected to each unit so as to be capable of information communication and controls each unit (not shown in the figure). The configuration of the control unit is not limited, but examples include those equipped with a CPU (Central Processing Unit) for performing information processing, a memory device, a recording medium, an information communication device, and the like. The control unit controls the operations of each unit according to a predetermined program and sends information (image information) including an image to the image irradiation unit 10.

[0026] The image irradiation unit 10 is a part that irradiates light including an image based on the image information from the control unit. The specific configuration of the image irradiation unit 10 is not limited, and for example, a conventionally known one such as a liquid crystal display device, an organic EL display device, or a combination of a laser light source and an optical modulation element can be used. In the example shown in FIG. 1, a device that irradiates light from the back side of the liquid crystal display device with a light emitting diode (LED: Light Emitting Diode) is used. As will be described later, the image irradiation unit 10 is configured to include a far - distance display area 13 and a near - distance display area 12 that respectively display a far - distance image and a near - distance image.

[0027] The optical branching unit 20 is an optical member that branches the light of the image irradiated from the image irradiation unit 10. It branches at least the first image displayed in the far display area 13 as the first image light and the second image displayed in the near display area 12 as the second image light. The structure of the optical branching unit 20 is not limited as long as it is an optical member that branches light. A prism may be used, or a method such as using a mirror to make the incident angle and reflection angle of light different may be used. In the example shown in FIG. 2, a prism is used as the optical branching unit 20, and the prism is arranged overlapping the far display area 13 of the image irradiation unit 10. Therefore, the first image light irradiated from the far display area 13 is reflected by the free-form mirror 41 through a path different from that of the second image light by the optical branching unit 20 and reaches the free-form mirror 32. Also, the second image light irradiated from the near display area 12 is reflected by the mirror 31 and reaches the free-form mirror 32.

[0028] Here, arranging the optical branching unit 20 overlapping the image irradiation unit 10 means that in a plan view, the area where the optical branching unit 20 is arranged overlaps the image display area of the image irradiation unit 10. Also, both the case where the optical branching unit 20 is in contact with the image irradiation unit 10 and the case where they are not in contact are included in the overlapping arrangement. Further, even when an optical member that transmits light is interposed between the optical branching unit 20 and the image irradiation unit 10, or a holding member for maintaining the distance between the two is interposed, it is included in the overlapping arrangement.

[0029] The first optical unit 30 is a combination of optical elements that irradiates the far image displayed in the far display area 13 as the first image light through the display unit in the viewpoint direction. The optical configuration of the first optical unit 30 is not limited, and a combination of a plurality of mirrors, lenses, prisms, etc. may be used. The second optical unit 40 is a combination of optical elements that irradiates the near image displayed in the near display area 12 as the second image light through the display unit in the viewpoint direction. The optical configuration of the second optical unit 40 is not limited, and a combination of a plurality of mirrors, lenses, prisms, etc. may be used.

[0030] The vibration detection unit 50 is a part that detects vibrations during the running of a vehicle on which the image projection device 100 is mounted and acquires vibration information. The specific configuration of the vibration detection unit 50 is not limited, but an acceleration sensor such as a conventionally known gyro sensor can be used. Here, a case where the vibration detection unit 50 is provided inside the image projection device 100 is shown, but vibration information may be acquired by a separately provided vibration detection unit 50 outside the image projection device 100, and the vibration information may be transmitted to the control unit of the image projection device 100 using information communication means, and the image projection device 100 may acquire the vibration information.

[0031] Based on the vibration information acquired by the vibration detection unit 50, the correction control unit 60 calculates a correction amount for the incident angle of the first image light from the first optical unit 30 to the display unit, and controls the optical drive unit 70 according to the correction amount to correct the imaging position of the first image. The correction control unit 60 is a function realized by a program executed by the control unit, and executes each step according to a predetermined procedure. Here, a case where the correction control unit 60 is provided inside the image projection device 100 is shown, but a separately provided correction control unit 60 outside the image projection device 100 may calculate a correction amount based on the vibration information, and the correction amount may be transmitted using information communication means. Also, a control signal for the optical drive unit 70 may be generated based on the correction amount calculated externally, and the driving of the optical drive unit 70 may be controlled using information communication means.

[0032] The optical drive unit 70 is a part that changes the incident angle of the first image light to the display unit by changing the optical path of the first optical unit 30. The configuration of the optical drive unit 70 is not limited, but for example, a motor device that changes the angles of the first optical unit 30 and the optical branching unit 20, or an optical element that electrically controls the traveling direction of light can be used. The optical drive unit 70 corresponds to the first optical drive unit in the present invention. When a motor device is used as the optical drive unit 70, it is preferable to use a stepping motor that can precisely control the rotation angle.

[0033] FIG. 2 is a schematic diagram showing the configuration of the image projection apparatus 100 according to the present embodiment. As shown in FIG. 2, the image projection apparatus 100 includes an image irradiation unit 10, an optical branching unit 20, a vibration detection unit 50, a correction control unit 60, an optical drive unit 70, a reflecting mirror 31, a free-form surface mirror 32, a free-form surface mirror 41, and an external light cut filter 80. Here, the combination of the free-form surface mirror 41 and the free-form surface mirror 32 constitutes the first optical unit 30 in the present invention, and the combination of the reflecting mirror 31, the free-form surface mirror 32, and the free-form surface mirror 41 constitutes the second optical unit 40 in the present invention.

[0034] In the example shown in FIG. 2, a part of the light irradiated from the image irradiation unit 10 irradiates the first image light in the viewing direction through the first optical unit 30 and the windshield (display unit). Further, another part of the light irradiated from the image irradiation unit 10 irradiates the second image light in the viewing direction through the second optical unit 40 and the windshield (display unit). Convex lenses or concave lenses may be arranged in the first optical unit 30 and the second optical unit 40 as necessary to enlarge or reduce the optical path. Further, the arrangement and orientation of the optical branching unit 20, the reflecting mirror 31, the free-form surface mirror 32, the free-form surface mirror 41, and the external light cut filter 80 are not limited to those shown in FIG. 2.

[0035] The reflecting mirror 31 is an optical member on which the second image light irradiated from the image irradiation unit 10 is incident and which reflects the first image light in the direction of the free-form surface mirror 32. In the example shown in FIG. 2, a convex mirror is shown as the reflecting mirror 31, but an optically designed one necessary for projecting the first image light as a virtual image can be used, and a concave mirror, a plane mirror, a free-form surface mirror, etc. can be used as necessary. Further, the reflecting mirror 31 may be omitted so that the first image light from the image irradiation unit 10 directly enters the free-form surface mirror 32.

[0036] The free-form surface mirror 32 is a concave mirror into which the second image light reflected by the reflecting mirror 31 is incident and which reflects the second image light in the direction of the windshield. The reflecting surface of the free-form surface mirror 32 is designed such that the optical path diameter expands in the direction of the driver's viewing point in order to project a virtual image through the windshield. Here, the expansion of the optical path diameter in the viewing point direction includes not only the case where the optical path diameter continuously expands after reflection, but also the case where the optical path diameter shrinks and forms an image at an intermediate point and then expands.

[0037] The free-form surface mirror 41 is an optical member into which the first image light is incident through the optical branching unit 20 and which reflects the first image light in the direction of the free-form surface mirror 32. The reflecting surface of the free-form surface mirror 41 is designed such that the optical path diameter expands in the direction of the driver's viewing point in order to project a virtual image through the windshield. Here, the expansion of the optical path diameter in the viewing point direction includes not only the case where the optical path diameter continuously expands after reflection, but also the case where the optical path diameter shrinks and forms an image at an intermediate point and then expands.

[0038] The external light cut filter 80 is an optical member having a wavelength characteristic of blocking infrared light and / or ultraviolet light and transmitting visible light, and is disposed on the optical path of the first image light between the image irradiation unit 10 and the windshield. FIG. 2 shows an example in which the external light cut filter 80 is disposed between the windshield and the free-form surface mirror 32, but the placement location is not limited as long as the external light incident on the image irradiation unit 10 can be cut. By disposing the external light cut filter 80, infrared light and / or ultraviolet light contained in external light such as sunlight incident from above the windshield are blocked. Thereby, it is possible to suppress a temperature rise and deterioration of the display surface when sunlight reaches the image display area of the image irradiation unit 10 through the free-form surface mirror 32, the reflecting mirror 31, and the free-form surface mirror 41. Further, since the external light cut filter 80 transmits visible light, the first image light transmits through the external light cut filter 80 well and has no influence on the projection of the virtual image.

[0039] The windshield (not shown) is provided in front of the driver's seat of the vehicle and is a portion that transmits visible light. The windshield corresponds to the display unit in the present invention because, on the inner surface of the vehicle, it reflects the first image light and the second image light incident from the free-form mirror 32 in the viewing direction and transmits the light from the outside of the vehicle in the viewing direction. Here, an example using the windshield as the display unit is shown, but a combiner may be prepared as the display unit separately from the windshield, and the light from the free-form mirror 32 may be reflected in the viewing direction. Further, it is not limited to being located in front of the vehicle, and it may be arranged on the side or the rear as long as it projects an image with respect to the passenger's viewing point.

[0040] The virtual image is an image that is displayed as if it were formed in space when the first image light and the second image light reflected by the windshield reach the viewing point (eyebox) of the driver or the like. The position where the virtual image is formed is determined by the spreading angle when the light irradiated from the image irradiation unit 10 travels in the viewing direction after being reflected by the reflecting mirror 31, the free-form mirror 32, the free-form mirror 41, and the windshield.

[0041] In the example shown in FIG. 2, the optical drive unit 70 is configured by a stepping motor, and the angle of the optical branching unit 20 is changed. In the present embodiment, during the running of the vehicle or the like, the correction control unit 60 calculates a correction amount based on the vibration information acquired by the vibration detection unit 50 and sends a control signal to the optical drive unit 70. The optical drive unit 70 is driven according to the control signal, the optical branching unit 20 is rotated with the direction perpendicular to the paper surface as the rotation axis, and the relative angle with the image irradiation unit 10 is changed. As a result, the optical path after the first image light passes through the optical branching unit 20 is changed, and the imaging position of the distant image moves in the vertical direction of the paper surface.

[0042] FIG. 3 is a schematic diagram showing a display area of an image irradiated from an image irradiating unit 10 in the image projection apparatus 100 according to the present embodiment. The entire display area 11 is the entire area where the image of the image irradiating unit 10 is displayed. A part of the entire display area 11 is a near display area 12, and the other part is a far display area 13. A first image is displayed in the far display area 13, and a second image is displayed in the near display area 12. Examples of the second image displayed in the near display area 12 include a speed and volume indicator, a traveling direction guide, and the like. Further, examples of the first image displayed in the far display area 13 include an image for attracting attention and auxiliary information related to driving such as emergency information.

[0043] In the image projection apparatus 100 shown in FIG. 2, a prism, which is an optical branching unit 20, is disposed at a position overlapping the far display area 13 to branch the paths of the first image light from the far display area 13 and the second image light from the near display area 12. The first image displayed in the far display area 13 reaches the driver's viewpoint via the optical branching unit 20, the free-form surface mirror 41, the free-form surface mirror 32, the external light cut filter 80, and the windshield. Further, the second image displayed in the near display area 12 reaches the driver's viewpoint via the mirror 31, the free-form surface mirror 32, the external light cut filter 80, and the windshield. Since the optical paths of the first image light and the second image light are expanded by the first optical unit 30 and the second optical unit 40, respectively, to reach the viewpoint, the driver visually recognizes the virtual images of the first image and the second image light as if they are formed at a predetermined distance. Here, the imaging position of the virtual image is such that the first image is farther from the viewpoint position than the second image.

[0044] FIG. 4 is a flowchart showing the steps of the image projection method according to the present embodiment. First, in the image irradiation step of step S1, a near image (second image) is displayed in the near display area 12 of the image irradiating unit 10, and a far image (first image) is displayed in the far display area 13, and they are irradiated as the second image light and the first image light, respectively. The irradiation of the first image light and the second image light and the imaging of the virtual image are the same as those described above. After irradiating the first image light and the second image light, the process proceeds to step S2.

[0045] Next, in the vibration detection step of step S2, the vibration detection unit 50 detects the vibration of the vehicle to obtain vibration information, and sends the obtained vibration information to the correction control unit 60. As a specific example, when an acceleration sensor is used for the vibration detection unit 50, the acceleration information detected by the acceleration sensor is sent to the correction control unit 60 as vibration information. Alternatively, the acceleration information detected by the acceleration sensor is integrated within a predetermined period to calculate the change amounts of speed and position, and the change amount of position is sent to the correction control unit 60 as vibration information. After sending the vibration information to the correction control unit 60, the process proceeds to step S3.

[0046] Next, in the correction amount calculation step of step S3, the correction control unit 60 generates a control signal for the optical drive unit 70 based on the obtained vibration information. When the acceleration information is obtained as the vibration information, it is integrated within a predetermined period to calculate the change amounts of speed and position, and the change amount of position is converted into the change amount of the incident angle on the windshield. Further, the rotation angle of the optical path in the first optical unit 30 is calculated from the change amount of the incident angle on the windshield, and a control signal is generated so as to change the optical path of the first optical unit 30 in the opposite direction of the rotation angle. As an example, when a prism, which is the optical branching unit 20, is provided in the optical drive unit 70 and the relative angle of the optical branching unit 20 with respect to the image irradiation unit 10 is changed, the rotation angle is obtained in consideration of the refractive index of the optical branching unit 20 and the incident angle of the first image light. After the correction control unit 60 generates the control signal, it sends the control signal to the optical drive unit 70, and the process proceeds to step S4.

[0047] Next, in the correction control step of step S4, based on the control signal generated in the correction amount calculation step, the optical drive unit 70 is driven to change the optical path of the first optical unit 30. When the optical drive unit 70 is provided in the optical branching unit 20, the optical branching unit 20 is rotated to change the incident angle on the free-form surface mirror 41. As a result, the imaging position of the virtual image is controlled in the direction opposite to the vibration of the vehicle, and the positional deviation from the background due to the vibration of the vehicle is canceled out, improving the visibility. After performing the drive control of the optical drive unit 70, the process proceeds to step S5.

[0048] Next, in the end determination step of step S5, it is determined whether to end the image irradiation method. If not, the process proceeds to step S1 and the feedback control of the vibration correction is continued. If it is to end, the control is ended by exiting the loop of the feedback control. Here, the correction amount calculation step and the correction control step have been described as separate steps, but the correction amount may also be calculated in the correction control step.

[0049] As described above, in the image projection apparatus 100 and the image projection method of the present embodiment, the first optical unit 30 is controlled based on the vibration information to correct the imaging position of the first image. Since the variation in the imaging position due to vibration is optically corrected by feedback control, it is not necessary to provide a margin area within the entire display area 11 as shown in FIG. 3. Therefore, an effective image display area can be secured, the areas of the near display area 12 and the far display area 13 can be increased, and large first and second images can be projected. As a result, it is possible to suppress the variation in the imaging position due to the vibration of the vehicle and improve the visibility of the image.

[0050] In the present embodiment, an example is shown in which a far image is irradiated as the first image light and a near image is irradiated as the second image light. However, the first image light may be imaged as a near image at a near position, and the second image light may be imaged as a far image at a far position. However, since the distance from the driver's viewpoint position to the imaging position of the far image is long, the deviation from the background caused by the blur of the imaging position due to vibration is likely to increase. Therefore, by imaging the first image light as a far image at a far distance and correcting the imaging position based on the vibration information, the effect of suppressing the positional deviation from the background and improving the visibility can be enhanced.

[0051] Moreover, by using a prism as the optical branching unit 20, alignment and optical design become easier when partially covering the image irradiation unit 10 and branching a part of the light. Also, compared with the case of using a reflecting mirror to branch light, by using a prism as the optical branching unit 20, the volume required for branching light can be reduced, and the apparatus can be miniaturized. Further, since the prism is smaller and lighter than the reflecting mirror 31, the free-form surface mirror 32, the free-form surface mirror 41, etc., the torque during the rotational operation by the optical driving unit 70 becomes smaller, and a low-output optical driving unit 70 can be used to achieve miniaturization. Also, since the prism is small and light, the accuracy during the rotational operation can be improved, and the rotational speed during correction can be increased.

[0052] As described above, in the image projection apparatus and the image projection method of the present embodiment, based on the vibration information, the correction amount of the incident angle of the first image light with respect to the windshield (display unit) is calculated, and the optical driving unit 70 is controlled according to the correction amount to correct the imaging position of the first image. Thereby, while securing an effective image display area, it is possible to suppress the variation in the imaging position due to the vibration of the vehicle and improve the visibility of the image.

[0053] (Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. 5. Descriptions of the contents overlapping with the first embodiment will be omitted. FIG. 5 is a schematic diagram showing the configuration of an image projection apparatus 110 according to the present embodiment. As shown in FIG. 5, the image projection apparatus 110 includes an image irradiation unit 10, optical branching units 20a, 20b, a reflecting mirror 31, a free-form surface mirror 32, a free-form surface mirror 41, a vibration detection unit 50, a correction control unit 60, optical driving units 70a, 70b, and an external light cut filter 80. In the present embodiment, the difference from the first embodiment is that optical branching units 20a, 20b and optical driving units 70a, 70b are provided to perform vibration correction for both the first optical unit 30 and the second optical unit 40.

[0054] In the image projection device 110 shown in FIG. 5, an optical branching unit 20a is disposed at a position overlapping the distant display area 13, and first image light from the distant display area 13 is branched in the direction of the free-form surface mirror 41. The optical branching unit 20a corresponds to the first optical branching unit in the present invention. Further, an optical branching unit 20b is disposed at a position overlapping the near display area 12, and second image light from the near display area 12 is branched in the direction of the mirror 31. The optical branching unit 20b corresponds to the second optical branching unit in the present invention.

[0055] In the image projection device 110, the first image displayed in the distant display area 13 reaches the driver's viewpoint through the optical branching unit 20a, the free-form surface mirror 41, the free-form surface mirror 32, the external light cut filter 80, and the windshield. Further, the second image displayed in the near display area 12 reaches the driver's viewpoint through the optical branching unit 20b, the mirror 31, the free-form surface mirror 32, the external light cut filter 80, and the windshield.

[0056] The optical drive units 70a and 70b are respectively provided on the optical branching units 20a and 20b to change the relative angles with respect to the image irradiation unit 10, and each corresponds to the first optical drive unit and the second optical drive unit in the present invention. The vibration detection unit 50 and the correction control unit 60 detect the vibration of the vehicle and individually control the optical drive units 70a and 70b based on the vibration information to correct the fluctuations in the imaging positions of the first image and the second image due to the vibration.

[0057] Also in the image projection device and the image projection method of the present embodiment, based on the vibration information, the correction amounts of the incident angles of the first image light and the second image light with respect to the windshield (display unit) are calculated, and the optical drive units 70a and 70b are controlled according to the correction amounts to correct the imaging positions of the first image and the second image. Thereby, while securing an effective image display area, it is possible to suppress the fluctuations in the imaging position due to the vibration of the vehicle and improve the visibility of the image.

[0058] (Third Embodiment) Next, a third embodiment of the present invention will be described. Descriptions of the content overlapping with the first embodiment will be omitted. In the first and second embodiments, the light irradiated from the image irradiation unit 10 is branched using the optical branching unit 20 and projected at different distances as a distant image and a near image to form a virtual image. However, even if the image displayed on the image irradiation unit 10 is one, a single virtual image may be formed by the first optical unit 30 without using the optical branching unit 20 and the second optical unit 40. In this case, the optical driving unit 70 can be provided on the free-form surface mirror 41 to change the relative angle of the free-form surface mirror 41 with respect to the image irradiation unit 10. At this time, the control of the optical driving unit 70 is the same as in the first embodiment. The vibration detection unit 50 acquires the vibration information of the vehicle, the correction control unit 60 calculates the correction amount based on the vibration information, and generates a control signal for controlling the driving of the optical driving unit 70.

[0059] Also in the image projection apparatus and the image projection method of the present embodiment, based on the vibration information, the correction amount of the incident angle of the first image light with respect to the windshield (display unit) is calculated, and the optical driving unit 70 is controlled according to the correction amount to correct the imaging positions of the first image and the second image. As a result, it is possible to suppress fluctuations in the imaging position due to vehicle vibration and improve the visibility of the image while ensuring an effective image display area.

[0060] The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope shown in the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention.

Description of Reference Numerals

[0061] 100, 110... Image projection apparatus 10... Image irradiation unit 11... Entire display area 12... Near display area 13... Distant display area 20, 20a, 20b... Optical branching unit 30... First optical unit 31... Reflecting mirror 32, 41... Free-form surface mirror 40…Second optical unit 50…Vibration detection unit 60…Correction control unit 70, 70a, 70b…Optical drive unit 80…External light cut filter

Claims

1. An image projection device that irradiates a projection image onto a display unit for displaying a virtual image, comprising: an image irradiation unit that irradiates a first image and a second image; a first optical unit that irradiates the first image as first image light in the viewpoint direction through the display unit; a second optical unit that irradiates the second image as second image light in the viewpoint direction through the display unit; an optical branching unit that branches the first image light and the second image light; a first optical driving unit that changes the angle of the optical branching unit with respect to the image irradiation unit based on vibration information, thereby changing the incident angle of the first image light with respect to the display unit.

2. The image projection device according to claim 1, further comprising: a vibration detection unit that detects vibration and acquires the vibration information; a correction control unit that calculates a correction amount of the incident angle based on the vibration information, controls the first optical driving unit according to the correction amount, and corrects the imaging position of the first image.

3. The image projection device according to claim 1 or 2, wherein the imaging position of the virtual image is such that the first image is farther from the viewpoint position than the second image.

4. The image projection device according to any one of claims 1 to 3, wherein the optical branching unit is a prism.

5. The image projection device according to any one of claims 1 to 4, further comprising: a second optical driving unit that changes the incident angle of the second image light with respect to the display unit based on the vibration information.

6. The image projection device according to any one of claims 1 to 5, wherein the first optical driving unit changes the angle of any one of the optical members constituting the first optical unit.

7. An image projection method for irradiating a projection image onto a display unit for displaying a virtual image, comprising: an image irradiation step of branching a first image as first image light and a second image as second image light by an optical branching unit and irradiating them in the viewpoint direction through the display unit; a vibration detection step of acquiring vibration information; a correction control step of changing the angle of the optical branching unit based on the vibration information, changing the incident angle of the first image light with respect to the display unit, and correcting the imaging position of the first image.

Images