Image projector and method for projecting image

Abstract

To provide an image projector and a method for projecting an image which can perform a precise initialization in image display position adjusting processing with a simple configuration.SOLUTION: An image projector (10) for projecting a virtual image through a display unit includes: an image radiation unit (11) for radiating image display light (GL) for forming a virtual image; a movable mirror (12) for guiding the image display light (GL) to the display unit; a driving unit (13) for rotating a reflection surface of the movable mirror (12) and changing the direction of the image display light (GL); a control unit (20) for controlling the driving unit (13); a control substrate (20a) equipped with the control unit (20); and a switch (15) equipped in the control substrate (20a). The control unit (20) specifies an initial position Pi of the movable mirror (12) on the basis of the contact of the movable mirror (12) and the switch (15).SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an image projection apparatus and an image projection method.

Background Art

[0002] Conventionally, as a device for displaying various information inside a vehicle, an instrument panel that lights up icons has been used. However, since the instrument panel is located below the vehicle's windshield (front glass), in order for the driver to visually recognize the information displayed on the instrument panel, it is necessary to move the line of sight downward during driving, which is not preferable. Therefore, an image projection device such as a head-up display (hereinafter referred to as "HUD": Head Up Display) has been proposed that projects an image onto the windshield so that information can be read when the driver visually recognizes the front of the vehicle.

[0003] In the conventional image projection device as described above, an image irradiation unit using a liquid crystal display device or the like irradiates irradiation light including an image (hereinafter referred to as "image display light"), and the irradiation light is reflected by one or a plurality of free-form mirrors (hereinafter sometimes referred to as "optical system") so that an image (virtual image, hereinafter referred to as "display image") is formed in space and reaches an eyebox of a driver or the like. As a result, the driver or the like can recognize that the display image is displayed at the imaging position in the depth direction in front of the vehicle by the image display light incident on the eyebox. Patent Document 1 discloses an example of such a conventional HUD.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] Here, the height of the above-mentioned glove box may vary for each driver. This is because the position of the driver's viewpoint varies depending on factors such as the driver's height and the position of the seat. Therefore, for each driver, it may be necessary to adjust the display position of the above-mentioned display image (hereinafter, "image display position") (hereinafter, "image display position adjustment"). As an example, the image display position adjustment can be performed by adjusting the inclination of a mirror included in the optical system. FIG. 5 shows an image projection apparatus 100 according to a prior art having an adjustment mechanism for the inclination of such a mirror.

[0006] As shown in FIG. 5, the image projection apparatus 100 includes an image irradiation unit 11, a fixed mirror 16, a movable mirror 12, a drive unit 13, and a control unit 50. The image display light GL irradiated from the image irradiation unit 11 is reflected by a windshield (not shown) and sent to the driver's viewpoint, and a display image is formed. The movable mirror 12 is provided with a drive unit 13 that rotates the movable mirror 12 in the direction of the double-headed arrow D shown in the figure to adjust the inclination of the image display light GL irradiated from the image irradiation unit 11 and reflected by the fixed mirror 16 in the direction D. In the image projection apparatus 100, the image display position adjustment is performed by the above configuration. The control unit 50 performs overall control of the image projection apparatus 100.

[0007] Here, a rotating body such as the movable mirror 12 that can be rotated by the drive unit 13 generally has various target positions that can change. Therefore, in such a rotating body, it is necessary to determine a position (hereinafter, "initial position") that serves as a reference for the rotation amount (for example, rotation angle). For example, by using a motor having an initial position setting function, movement to the initial position (hereinafter, "initialization") can be performed. However, such a motor is generally expensive and is not preferable from the viewpoint of cost reduction. Therefore, there is a demand for an image projection apparatus with a simple configuration and a reduced price. Furthermore, the accuracy of detecting the initial position must be maintained.

[0008] Therefore, the present invention has been made in view of the above-described conventional problems, and an object thereof is to provide an image projection apparatus and an image projection method capable of performing highly accurate initialization with a simple configuration in image display position adjustment processing.

Means for Solving the Problems

[0009] In order to solve the above problems, an image projection apparatus of the present invention is an image projection apparatus that projects a virtual image through a display unit, and includes an image irradiation unit that irradiates image display light for forming the virtual image, a reflection unit that guides the image display light to the display unit, a drive unit that rotates a reflection surface of the reflection unit to change a direction of the image display light, a control unit that controls the drive unit, a substrate on which the control unit is mounted, and a position detection unit of the reflection unit mounted on the substrate. The control unit specifies an initial position of the reflection unit based on a detection result of the position detection unit.

[0010] In such an image projection apparatus of the present invention, an image irradiation unit that irradiates image display light for forming a virtual image, a reflection unit that guides the image display light to the display unit, a drive unit that rotates a reflection surface of the reflection unit to change a direction of the image display light, a control unit that controls the drive unit, a substrate on which the control unit is mounted, and a position detection unit of the reflection unit mounted on the substrate are provided, and the control unit specifies an initial position of the reflection unit based on a detection result of the position detection unit. As a result, in image display position adjustment processing, it becomes possible to perform highly accurate initialization with a simple configuration.

[0011] Further, in one aspect of the present invention, the position detection unit is a contact type switch having a contact, the substrate is disposed behind the reflection unit, and the initial position of the reflection unit is specified based on contact between a back surface of the reflection unit and the contact of the contact type switch.

[0012] Further, in one aspect of the present invention, the control unit rotates the reflection unit in a first direction, once stops at the initial position, then rotates in a second direction opposite to the first direction, and stops at a standby position of the reflection unit.

[0013] In addition, in one aspect of the present invention, the image display light forms a virtual image through the display unit, and the initial position is used to specify the reference position of the reflection unit when adjusting the position of the virtual image.

[0014] In order to solve the above problems, an image projection method of the present invention is an image projection apparatus that projects a virtual image through a display unit, and includes an image irradiation unit that irradiates image display light for forming the virtual image, a reflection unit that guides the image display light to the display unit, a drive unit that rotates a reflection surface of the reflection unit to change a direction of the image display light, a control unit that controls the drive unit, a substrate on which the control unit is mounted, and a position detection unit of the reflection unit mounted on the substrate. The image projection method uses the image projection apparatus, and is characterized in that the control unit specifies an initial position of the reflection unit based on a detection result of the position detection unit.

Advantages of the Invention

[0015] In the present invention, it is possible to provide an image projection apparatus and an image projection method capable of performing high-precision initialization with a simple configuration in image display position adjustment processing.

Brief Description of the Drawings

[0016]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0017] 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 redundant explanations will be omitted as appropriate. In the following description, a form in which the image projection device in the present invention is applied to a HUD mounted on a vehicle or the like will be exemplified and described. The HUD of the present embodiment displays, for example, driving support information that assists the driver's driving.

[0018] With reference to FIGS. 1 to 4, an image projection device and an image projection method according to the present embodiment will be described. FIG. 1 is a longitudinal sectional view showing an example of the configuration of an image projection device 10 according to the present embodiment. The main body of the image projection device 10 is disposed, for example, below the dashboard of the vehicle. As shown in FIG. 1, the image projection device 10 includes an image irradiation unit 11, a movable mirror 12, a drive unit 13, a switch 15, a fixed mirror 16, a control unit 20, a control board 20a, a housing 30, and a light transmissive unit 31. In FIG. 1, the traveling direction of the vehicle is the left direction of the paper surface.

[0019] The image irradiation unit 11 irradiates image display light GL for forming a display image in front of the vehicle. The image irradiation unit 11 is configured, for example, by a liquid crystal panel, an organic EL panel, or the like. FIG. 1 also shows the path of the image display light GL. That is, the image display light GL irradiated from the image irradiation unit 11 passes through the light transmissive unit 31 provided in a part of the housing 30 described later and heads toward a windshield (not shown). Note that the "windshield" is an example of the "display unit" according to the present invention.

[0020] The fixed mirror 16 is a fixed reflecting member having no movable part, and reflects the image display light GL irradiated from the image irradiation unit 11 toward the movable mirror 12. Note that the fixed mirror 16 is an auxiliary configuration, and may be omitted so that the image display light GL from the image irradiation unit 11 is directly irradiated onto the movable mirror 12.

[0021] The movable mirror 12 is an optical member that guides the image display light GL irradiated from the image irradiation unit 11 to the windshield. The form of the movable mirror 12 is not particularly limited, but in this embodiment, a concave mirror is used. The image display light GL irradiated on the windshield is reflected by the windshield, forming an instrument panel for the driver and forming a display image as a virtual image in front of the vehicle. As a result, the line-of-sight movement for the driver to visually recognize the driving support information can be reduced. In this embodiment, an optical system using two mirrors, namely the fixed mirror 16 and the movable mirror 12, is illustrated and described, but the present invention is not limited to this, and other reflecting members such as free-form mirrors may be included. Note that the "movable mirror 12" is an example of the "reflecting part" according to the present invention.

[0022] The drive unit 13 includes a motor 13a and has a function of changing the rotation angle of the movable mirror 12 in the vertical plane around the rotation mechanism 13b in the initialization process of the movable mirror 12 described later. That is, the movable mirror 12 according to this embodiment is rotatable in the directions of arrow D1 and arrow D2 around the rotation axis of the rotation mechanism 13b engaged with the motor 13a. Here, the "vertical plane" according to this embodiment refers to a plane perpendicular to the ground. The motor to be used is not particularly limited, and for example, a synchronous motor that operates in synchronization with the input pulse power, or a stepping motor, etc. can be used. In this embodiment, a form using the rotation mechanism 13b engaged with the motor 13a is illustrated and described, but the present invention is not limited to this, and the orientation of the movable mirror 12 may be directly changed around the rotation axis of the motor 13a.

[0023] The control unit 20 comprehensively controls the entire image projection apparatus 10 and executes an image display position adjustment program described later. The control unit 20 includes a CPU, a ROM, a RAM, etc. (not shown). Note that the control unit 20 may be an ECU (Engine Control Unit) of a vehicle on which the image projection apparatus 10 is mounted. The control unit 20 according to the present embodiment is configured as an LSI as an example and is mounted on a control board 20a. The control board 20a is configured by, for example, a printed circuit board. Details of the control board 20a will be described later. Note that the "control board 20a" is an example of the "board" according to the present invention.

[0024] The switch 15 has a function of detecting an initial position Pi in an initialization process described later. The switch 15 is configured by, for example, a contact switch or the like and is mounted on the control board 20a. Details of the switch 15 will be described later. Note that the "switch 15" is an example of the "position detection unit" according to the present invention.

[0025] The housing 30 houses the above configuration inside and constitutes one unit. A light-transmitting portion 31 is provided in a part of the housing 30 to transmit the image display light GL from the image irradiation unit 11. The light-transmitting portion 31 is formed of, for example, a transparent resin or the like.

[0026] Next, with reference to FIG. 2, the electrical configuration of the image projection device 10 according to the present embodiment will be described. As shown in FIG. 2, the image projection device 10 includes a control unit 20, an image irradiation unit 11, a drive unit 13, a switch 15, and a storage unit 24. The control unit 20 is connected to the HCU 40. The HCU (Human Machine Interface Control Unit) 40 is one of the in-vehicle ECUs and has a function of controlling the Human Machine Interface (HMI) system. The HMI includes an input interface function for receiving operations by the vehicle driver and an output interface function for presenting information to the driver. The input / output interface 41 is a part that provides these interface functions to the driver, mainly inputs operation instructions by the driver, and displays various information to the driver. The input / output interface 41 is not particularly limited and can be configured by a liquid crystal panel, an organic EL panel, or the like. Also, the input / output interface 41 may be configured to receive operations through a touch panel. Further, the HCU 40 sends an instruction corresponding to the operation content input from the driver to the control unit 20.

[0027] The control unit 20 includes a processing unit 21, a drive control signal generation unit 22, and an image control signal generation unit 23. The processing unit 21 mainly controls the image irradiation unit 11, the drive unit 13, the switch 15, and the storage unit 24 based on the image display position adjustment instruction from the HCU 40 and the image display position for each driver stored in the storage unit 24. The drive control signal generation unit 22 generates an instruction signal for rotating the movable mirror 12. The instruction signal is sent to the motor 13b, and as a result, the drive unit 13 is controlled. The image control signal generation unit 23 generates a signal for irradiating the image display light GL from the image irradiation unit 11.

[0028] The storage unit 24 is a storage means that stores an image display position adjustment program and the like in the image display position adjustment process (described later) executed by the image projection device 10. Information related to the adjustment of the image display position, such as the image display position for each driver, may be stored in the storage unit 24. The form of the storage unit 24 is not particularly limited, and for example, a RAM, an HDD (Hard Disk Drive), or the like can be used.

[0029] Next, with reference to FIG. 3, a method for adjusting the image display position in the image projection device 10 will be described. FIG. 3 is a flowchart showing the processing flow of an image display position adjustment program that describes the image display position adjustment process executed by the control unit 20. This image display position adjustment program is stored in the storage unit 24 or storage means such as a ROM (not shown), read by the CPU, and expanded and executed in a RAM or the like.

[0030] Here, the outline of the image display position adjustment executed by the image projection device 10 according to this embodiment is as follows. That is, when an image display position adjustment instruction is given from the input / output interface 41 by the driver, the instruction is sent to the control unit 20 via the HCU 40. The control unit 20 that has received the image display position adjustment instruction rotates the movable mirror 12 based on the image display position adjustment program, and the adjustment of the image display position is executed. In the image display position adjustment process, an initialization process for detecting the initial position Pi of the movable mirror 12, which is one of the features of the image projection device 10 according to this embodiment, is executed.

[0031] With reference to FIG. 3, in step S10, the control unit 20 waits until it receives a start instruction from the HCU 40. The start instruction is generated, for example, when the vehicle engine is started.

[0032] In step S11, the control unit 20 determines whether the initialization process of the movable mirror 12 has already been executed. Information on whether the initialization process has been executed is held in storage means such as the storage unit 24, for example. If the determination is negative, the process proceeds to step S12, and if the determination is positive, the process proceeds to step S16.

[0033] In step S12, the control unit 20 controls the drive unit 13 to rotate the movable mirror 12 in the D1 direction shown in FIG. 1.

[0034] In step S13, the control unit 20 waits until it receives a contact signal from the switch 15. The contact signal is a signal indicating that the movable mirror 12 has contacted the switch 15. When the contact signal is received for the first time, in order to indicate that the initialization process has already been executed, that fact is stored in a storage means such as the storage unit 24.

[0035] In step S14, the control unit 20 controls the drive unit 13 to stop the rotation of the movable mirror 12. The stop position of this movable mirror 12 is the initial position Pi.

[0036] In step S15, the control unit 20 controls the drive unit 13 to rotate the movable mirror 12 in the D2 direction and stop it at the standby position Ps. The standby position Ps is a reference position of the movable mirror 12 when performing the image display position adjustment process. The standby position Ps can be appropriately set in consideration of, for example, the movable range of the movable mirror 12. As an example, the substantially central position of the movable range of the movable mirror 12 can be set as the standby position. Note that the standby position Ps may be the initial position Pi.

[0037] In step S16, the control unit 20 determines whether it has received an image display position adjustment instruction from the HCU 40. If the determination is affirmative, the process proceeds to step S17, and if the determination is negative, the process proceeds to step S18. Steps S12 to S15 are the initialization process according to the present embodiment.

[0038] In step S17, the control unit 20 executes the image display position adjustment process. More specifically, based on the specific instruction of the image display position input from the input / output interface 41 by the driver and received via the HCU 40, the drive unit 13 is controlled to rotate the movable mirror 12 from the standby position Ps to the position corresponding to the instruction.

[0039] In step S18, the control unit 20 determines whether it has received an end instruction for the image projection device 10. If the determination is negative, the process proceeds to step S11. If the determination is positive, the present image display position adjustment program ends. That is, in the present embodiment, while the vehicle engine is running, the loop between step S11 and step S18 is repeated, so it is possible to respond to the image display position adjustment instruction during that period. Note that the determination of whether the end instruction has been received may be made based on, for example, an engine stop signal or the like.

[0040] Next, referring to FIG. 4, a perspective view of the image projection device 10 will be described. FIG. 4 shows a configuration close to the actual one, where (a) shows an example of the overall configuration of the image projection device 10, and (b) shows an example of the configuration around the movable mirror 12.

[0041] In the image projection device 10 according to the present embodiment, the image irradiation unit 11, the movable mirror 12, the fixed mirror 16, and the control board 20a are arranged as shown in FIG. 4(a) as an example. On the control board 20a, a control unit 20 as a control LSI and a switch 15 etc. are mounted (not shown). And the back surface of the movable mirror 12 and the switch 15 on the control board 20a face each other. Since the switch 15 is mounted on the control board 20a in the image projection device 10, a board and wiring for the switch 15 are unnecessary, resulting in a simple configuration. Also, since the movable mirror 12 and the switch 15 are in direct contact, there is little variation, and it is possible to detect the initial position Pi with high accuracy.

[0042] As shown in Fig. 4(b), in this embodiment, the control board 20a is arranged behind the movable mirror 12, and the back surface of the movable mirror 12 faces the switch 15 (the illustration of the control unit 20 is omitted in Fig. 4(b)). Therefore, the initial position Pi of the movable mirror 12 can be detected with high precision. Note that arranging the control board 20a behind the movable mirror 12 is just an example, and the arrangement position of the control board 20a is free as long as contact between the back surface of the movable mirror 12 and the switch 15 can be ensured. The switch 15 may be mounted on the control board 20a via a dedicated pedestal. Providing a pedestal facilitates height adjustment of the switch 15. Also, a reinforcing member may be provided at the contact position with the switch 15 on the back surface of the movable mirror 12. Wear of the movable mirror 12 can be suppressed by the reinforcing member.

[0043] In this embodiment, a form in which a contact switch is adopted as the switch 15 has been exemplified and described, but the present invention is not limited to this, and a non-contact switch may be adopted. For example, a photoelectric switch having a light projecting unit and a light receiving unit is adopted as the switch 15, and a reflector is provided at a portion corresponding to the initial position of the movable mirror 12. In this form, the position where the reflected light emitted from the light projecting unit and reflected by the reflector is received by the light receiving unit is taken as the initial position.

[0044] As described in detail above, according to the image projection apparatus and the image projection method according to this embodiment, In the image display position adjustment process, it is possible to provide an image projection apparatus and an image projection method capable of performing high-precision initialization with a simple configuration.

Explanation of Reference Numerals

[0045] 10, 100... Image projection apparatus 11... Image irradiation unit 12... Movable mirror 13... Driving unit 13a... Motor 13b... Rotation mechanism 15... Switch 16... Fixed mirror 20... Control unit 20a... Control board 21... Processing unit 22... Drive control signal generation unit 23... Image control signal generation unit 24... Memory unit 30... Housing 31... Light-transmitting part 40... HCU 41... Input / output interface 50... Control unit D, D1, D2... Directions GL... Image display light Pi... Initial position Ps... Standby position

Claims

1. An image projection apparatus that projects a virtual image through a display unit, comprising: an image irradiation unit that irradiates image display light for forming the virtual image; a reflection unit that guides the image display light to the display unit; a drive unit that rotates a reflection surface of the reflection unit to change a direction of the image display light; a control unit that controls the drive unit; a substrate on which the control unit is mounted; and a position detection unit of the reflection unit mounted on the substrate, wherein the control unit specifies an initial position of the reflection unit based on a detection result of the position detection unit. The image projection apparatus is characterized by this.

2. The image projection apparatus according to claim 1, wherein the position detection unit is a contact type switch having contacts, the substrate is disposed behind the reflection unit, and the initial position of the reflection unit is specified based on contact between a back surface of the reflection unit and the contacts of the contact type switch. The image projection apparatus is characterized by this.

3. The image projection apparatus according to claim 1, wherein the control unit rotates the reflection unit in a first direction, temporarily stops it at the initial position, then rotates it in a second direction opposite to the first direction, and stops it at a standby position of the reflection unit. The image projection apparatus is characterized by this.

4. The image projection apparatus according to claim 1, the image display light forms a virtual image through the display unit, and the initial position is used for specifying a reference position of the reflection unit when adjusting the position of the virtual image. The image projection apparatus is characterized by this.

5. An image projection device that projects a virtual image through a display unit, comprising an image irradiation unit that irradiates image display light for forming the virtual image, a reflection unit that guides the image display light to the display unit, a drive unit that rotates a reflection surface of the reflection unit to change a direction of the image display light, a control unit that controls the drive unit, a substrate on which the control unit is mounted, and a position detection unit of the reflection unit mounted on the substrate. An image projection method using the image projection device, wherein: The control unit specifies an initial position of the reflection unit based on a detection result of the position detection unit.

Images