Image projection device and image projection method

Abstract

Provided are an image projection device and an image projection method that make it possible to, with a simple configuration, effectively suppress an increase in the temperature of an image irradiation part due to external light. An image projection device (10) projects a virtual image via a display part, and is characterized by comprising an image irradiation part (11) that performs irradiation with image display light (GL) for forming the virtual image; and a reflection mirror (12) that guides the image display light (GL) to the display part. The image projection device (10) is also characterized by, if a predetermined condition is satisfied, changing the orientation of the reflection mirror (12) such that light (SL) incident on the reflection mirror (12) from the direction of the display part is not incident on the image irradiation part (11).

Description

Image projection device and image projection method

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

[0002] Conventionally, an instrument panel that displays icons by lighting them has been used as a device for displaying various types of information inside a vehicle. However, because the instrument panel is located below the windshield (front glass) of the vehicle, the driver must move their eyes downward while driving in order to see the information displayed on the instrument panel, which is undesirable. Therefore, image projection devices such as head-up displays (hereinafter referred to as "HUDs") have been proposed that project images onto the windshield so that the driver can read information when looking ahead of the vehicle.

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

[0004] Japanese Patent Application Laid-Open No. 2022-156071

[0005] In the HUDs of the above-described conventional technology, it is conceivable that sunlight, which is external light concentrated by the optical system, may strike the image projection unit by tracing the optical path from the image projection unit to the driver's eyebox in reverse. If sunlight is irradiated onto the image projection unit for a long period of time, the heat from the sunlight may increase the temperature of the image projection unit, potentially causing it to exceed its rated temperature. This may result in a malfunction of the image projection unit. Therefore, there is a need for an image projection device that can protect the image projection unit from exposure to sunlight as external light. It is also important that such an image projection device has a simple configuration, independent of the optical system configuration. The image projection device disclosed in Patent Document 1 addresses the issue of suppressing the temperature rise of the image projection unit due to external light, but the image projection device disclosed in Patent Document 1 solves this issue by devising an imaging method in the optical system.

[0006] Therefore, the present invention has been made in consideration of the above-mentioned conventional problems, and aims to provide an image projection device and an image projection method that have a simple configuration and can effectively suppress the temperature rise of the image irradiation section due to external light.

[0007] In order to solve the above problem, the image projection device of the present invention is an image projection device that projects a virtual image via a display unit, and is equipped with an image irradiation unit that irradiates image display light to form the virtual image, and a reflection unit that guides the image display light to the display unit, and is characterized in that when predetermined conditions are met, the reflection unit changes its orientation so that light incident on the reflection unit from the direction of the display unit does not enter the image irradiation unit.

[0008] The image projection device of the present invention includes an image projection unit that projects image display light to form a virtual image, and a reflector that directs the image display light to the display unit, and when a predetermined condition is satisfied, changes the orientation of the reflector so that light incident on the reflector from the direction of the display unit does not enter the image projection unit. As a result, a temperature rise in the image projection unit due to external light can be effectively suppressed with a simple configuration.

[0009] In one aspect of the present invention, the light incident on the reflecting portion from the direction of the display portion is sunlight.

[0010] In one aspect of the present invention, the reflecting unit has two positions: an operating position where the image display light is directed to the display unit, and a retracted position where light incident on the reflecting unit from the direction of the display unit is not allowed to be incident on the image irradiating unit; and further includes a temperature monitoring unit that monitors the temperature of the image irradiating unit; a drive unit that rotates the reflecting unit in a vertical plane around a rotation axis; and a control unit that controls the drive unit to change the position of the reflecting unit from the operating position to the retracted position when the temperature monitored by the temperature monitoring unit exceeds a predetermined retraction judgment temperature.

[0011] In one aspect of the present invention, the control unit is further configured to control the position of the reflection unit to change from the operating position to the retracted position when receiving an instruction to terminate operation of the image projection device.

[0012] In one aspect of the present invention, the control unit stops the irradiation of image display light by the image irradiation unit before changing the position of the reflecting unit from the operating position to the retracted position.

[0013] In one aspect of the present invention, when the monitoring temperature becomes equal to or lower than a predetermined return judgment temperature after the reflection unit has temporarily retreated to the retreat position, the control unit changes the position of the reflection unit from the retreat position to the operating position and resumes irradiating the image display light in the image irradiation unit.

[0014] In addition, in one aspect of the present invention, when the operating position is changed by adjusting the position of the eye box formed by the image display light being reflected by the display unit, the control unit stops irradiating the image display light in the image irradiation unit and waits for the time it takes to move from the retracted position to the changed operating position.

[0015] In order to solve the above problem, the image projection method of the present invention is an image projection method using an image projection device that projects a virtual image via a display unit, and is equipped with an image irradiation unit that irradiates image display light to form the virtual image, and a reflection unit that directs the image display light to the display unit, and is characterized in that when a predetermined condition is met, the orientation of the reflection unit is changed so that light incident on the reflection unit from the direction of the display unit does not enter the image irradiation unit.

[0016] The present invention can provide an image projection device and an image projection method that can effectively suppress a temperature rise in an image irradiation unit due to external light with a simple configuration.

[0017] 1A is a longitudinal cross-sectional view showing an example of the configuration of an image projection device according to an embodiment; FIG. 1B is a longitudinal cross-sectional view showing the operating position of a reflecting mirror; and FIG. 1C is a longitudinal cross-sectional view showing the retracted position of the reflecting mirror. In the image projection device according to an embodiment, FIG. 1A is a longitudinal cross-sectional view explaining the path of sunlight; FIG. 1B is a plan view showing the positional relationship between the sunlight irradiation area and the image projection unit when the reflecting mirror is in the operating position; and FIG. 1C is a plan view showing the positional relationship between the sunlight irradiation area and the image projection unit when the reflecting mirror is in the retracted position. FIG. 1C is a block diagram showing an example of the configuration of an image projection device according to an embodiment. FIG. 1D is a flowchart showing the processing flow of a main routine of a reflecting mirror driving program executed by an image projection device according to a first embodiment. FIG. 1E is a flowchart showing the processing flow of a temperature abnormality processing subroutine of a reflecting mirror driving program executed by an image projection device according to a second embodiment. FIG. 1F is a diagram showing a differential angle-operating time comparison table referenced by an image projection device according to a second embodiment.

[0018] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing will be denoted by the same reference numerals, and redundant explanations will be omitted as appropriate. In the following description, an embodiment in which the image projection device of the present invention is applied to a HUD mounted on a vehicle or the like will be described as an example.

[0019] (First embodiment) An image projection device and an image projection method according to this embodiment will be described with reference to Figures 1 to 5. Figure 1(a) is a longitudinal cross-sectional view 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 disposed, for example, below the dashboard of a vehicle. As shown in Figure 1(a), the image projection device 10 includes an image irradiation unit 11, a reflecting mirror 12, a driving unit 13, a temperature monitoring unit 14, a control unit 20, a housing 30, and a light-transmitting unit 31. In Figure 1(a), the traveling direction of the vehicle is the -Y direction, and the height direction of the vehicle is the Z-axis direction.

[0020] The image projection unit 11 projects image display light to form a virtual image ahead of the vehicle. The image projection unit 11 is configured, for example, with a liquid crystal panel, an organic EL panel, or the like. FIG. 1B shows the path of the image display light. That is, the image display light GL projected from the image projection unit 11 passes through a light-transmitting portion 31 provided in a part of a housing 30 (described later) and heads toward a windshield (not shown). The "windshield" is an example of the "display unit" according to the present invention.

[0021] The reflector 12 is an optical system that guides the image display light GL emitted from the image projection unit 11 to the windshield. The shape of the reflector 12 is not particularly limited, but in this embodiment, a concave mirror is used. The image display light emitted to the windshield is reflected by the windshield, forming an eye box for the driver and forming a virtual image in front of the vehicle. This reduces the amount of line-of-sight movement required by the driver to visually recognize the driving assistance information. Note that this embodiment will be described using an optical system with one reflector 12 as an example, but this is not limiting and the system may include other reflective members such as a free-form mirror. Note that the "reflector 12" is an example of a "reflecting unit" according to the present invention.

[0022] The drive unit 13 includes a motor 13a and has the function of changing the rotation angle of the reflecting mirror 12 in a vertical plane as needed. That is, the reflecting mirror 12 in this embodiment is rotatable in the direction of the double-headed arrow D around the rotation axis of the rotation mechanism 13b, which is engaged with the motor 13a and extends in the X-axis direction. Here, the "vertical plane" in this embodiment refers to a plane perpendicular to the ground, i.e., the Y-Z plane shown in FIG. 1(a). The motor used is not particularly limited, and examples include a synchronous motor that operates in synchronization with input pulse power, a stepping motor, and the like. Note that this embodiment has been described with an example in which a rotation mechanism 13b engaged with the motor 13a is used, but this is not limiting. The orientation of the reflecting mirror 12 may also be changed directly around the rotation axis of the motor 13a.

[0023] In this embodiment, a leveling actuator for a headlamp or the like is used as the motor 13a. A leveling actuator is a motor used in an auto-leveling system for a vehicle's headlamps. A headlamp auto-leveling system is a system that automatically adjusts the illumination range (vertical direction) of the headlamp according to the fore-aft inclination of the vehicle. This system aims to prevent dazzling to those around the vehicle caused by the headlamp when the fore-aft inclination of the vehicle changes due to an increase or decrease in the number of occupants, the presence or absence of luggage, acceleration or deceleration while driving, etc., and to ensure the necessary illumination range. Because both motors are used in common in that they move the headlamp up and down, the control software can also be reused. This allows for the sharing of components, which also contributes to cost reduction.

[0024] For the sake of convenience, the position of the reflecting mirror 12 is defined as a rotation angle θ (hereinafter referred to as "position angle θ") of the rotation direction D of the rotation mechanism 13b with respect to the horizontal line h shown in FIG. 1(a). However, the reference position is not limited to this, and may be another position, for example, the irradiation direction of the image display light GL from the image irradiation unit 11. Furthermore, the method of defining the position is not limited to the position angle, and may be, for example, the stroke amount of the motor 13a. Here, the position angle θ in the state shown in FIG. 1(b) is referred to as an "operation angle θ". ｗ The position of the reflecting mirror 12 in this state is called the "operating position."

[0025] The temperature monitoring unit 14 has a function of monitoring the temperature of the image projection unit 11. The form of the temperature monitoring unit 14 is not particularly limited, but for example, it is configured by attaching a thermistor to a part of the image projection unit 11. The monitored temperature monitored by the temperature monitoring unit 14 is sent to the control unit 20, which will be described later.

[0026] The control unit 20 controls the entire image projection device 10 and executes a reflecting mirror driving program, which will be described later. The control unit 20 includes a CPU, ROM, RAM, etc., which are not shown. The control unit 20 may be an ECU (Engine Control Unit) of a vehicle in which the image projection device 10 is mounted.

[0027] The housing 30 accommodates the above-described components and forms a single unit. The light-transmitting portion 31 is disposed in a part of the housing 30 and has a function of transmitting the image display light GL from the image irradiating portion 11. The light-transmitting portion 31 is formed of a transparent resin or the like.

[0028] Here, the retracted position of the reflecting mirror 12 will be described with reference to FIG. 1C. As described above, the image projection device 10 according to this embodiment aims to effectively suppress a temperature rise in the image projection unit 11 due to external light. FIG. 2A shows the path of sunlight SL, which is external light irradiated from the windshield direction, when the reflecting mirror 12 is in the operating position. As shown in FIG. 2A, sunlight SL traveling along the irradiation path of the image display light GL reverses the irradiation path and enters the image projection unit 11. This causes a temperature rise in the image projection unit 11. To avoid this, when the temperature monitoring unit 14 detects an abnormal monitored temperature, the image projection device 10 controls the reflecting mirror 12 to prevent sunlight SL from directly hitting the image projection unit 11, as shown in FIG. 1C. That is, the reflecting mirror 12 is rotated in the direction indicated by LD to divert sunlight SL away from the image projection unit 11. The area of ​​the housing 30 on which sunlight SL hits after the control is referred to as the "retraction area LA." The position of the reflecting mirror 12 shown in FIG. 1C is called the "retracted position," and the position angle of the reflecting mirror 12 is called the "retracted angle θ ｅThe operation of retracting reflector 12 to the retracted position is referred to as the "retraction operation." Note that the retraction area LA of housing 30 may be provided with a light absorber that absorbs sunlight SL, a light shield against sunlight SL, or the like, so that the sunlight SL is not scattered to other areas within the housing.

[0029] Here, it is considered that the intensity of sunlight SL shown in FIG. 2A changes depending on the position of the sun throughout the day. In order to deal with this, the retraction angle θ is set to be more efficient by taking into account the position of the sun throughout the day. ｅ Alternatively, the retraction angle θ may be set according to the time of day. ｅ may be changed.

[0030] FIG. 2B is a plan view showing the positional relationship between the irradiation area SA1 of sunlight SL and the image projection unit 11 when the reflecting mirror 12 is in the operating position, and FIG. 2C is a plan view showing the positional relationship between the irradiation area SA2 of sunlight SL and the image projection unit 11 when the reflecting mirror 12 is in the retracted position. During normal display operation, the irradiation area SA1 of sunlight SL overlaps with the image projection unit 11 as shown in FIG. 2B. However, when the retraction operation is performed, the irradiation area SA2 of sunlight SL shifts above the image projection unit 11, so that sunlight SL no longer directly hits the image projection unit 11. Note that, in this embodiment, an example is described in which the irradiation area of ​​sunlight SL is shifted above the image projection unit 11. However, this is not limiting and the irradiation area SA1 may be shifted to another part of the housing 30, for example, downward. To retract the irradiation area SA1 laterally in FIG. 2B, the drive unit 13 may be rotated in that direction.

[0031] Next, the electrical configuration of the image projection device 10 according to this embodiment will be described with reference to FIG. 3 . As shown in FIG. 3 , the image projection device 10 includes an image projection unit 11, a motor 13a, a temperature monitoring unit 14, a storage unit 24, and a control unit 20. The control unit 20 is connected to an HCU 40. The HCU (Human Machine Interface Control Unit) 40 is one of the vehicle ECUs and has the function of controlling a Human Machine Interface (HMI) system. The HMI has an input interface function for accepting operations by the vehicle driver and an output interface function for presenting information to the driver. The HCU 40 sends instructions corresponding to the operations input by the driver to the control unit 20. The HCU 40 also acquires information such as the position angle of the reflecting mirror 12 from the control unit 20.

[0032] The control unit 20 includes a processing unit 21, a drive signal generation unit 22, and an image signal generation unit 23. The processing unit 21 controls the motor 13a and the image projection unit 11 mainly based on monitored temperature information from the temperature monitoring unit 14, each determined temperature (described later) from the memory unit 24, and the like. The processing unit 21 acquires instructions from the HCU 40 corresponding to operations input by the driver, and the like. The processing unit 21 also sends information such as the position angle of the reflecting mirror 12 to the HCU 40. The drive signal generation unit 22 generates a signal to control the motor 13a of the drive unit 13, and the image signal generation unit 23 generates a signal to control the display image in the image projection unit 11.

[0033] The storage unit 24 stores the respective determination temperatures and the operating angle θ in the reflecting mirror driving process (described later) executed by the image projection device 10. ｗ , retraction angle θ ｅ , a reflecting mirror driving program, etc. The form of the storage unit 24 is not particularly limited, but for example, a ROM, a HDD (Hard Disk Drive), etc. can be used.

[0034] A method for controlling the reflecting mirror 12 in the image projection device 10 will be described with reference to Figures 4 and 5. Figure 4 is a flowchart showing the flow of processing of a reflecting mirror drive program that describes the reflecting mirror drive process executed in the image projection device 10. This reflecting mirror drive program is stored in a storage means such as a ROM (not shown), and is read out by the CPU, expanded into a RAM, etc., and executed. In the flowchart shown in Figure 4, it is assumed that an instruction to start operation has already been sent from the HCU 40 to the control unit 20. Furthermore, the reflecting mirror 12 is in a retracted position, and the position angle θ is the retraction angle θ ｅ It is as follows.

[0035] In step S10, the control unit 20 performs initialization processing as necessary. For example, the control unit 20 checks the position angle of the reflecting mirror 12. The reflecting mirror 12 is normally in a retracted position. After checking the position, the control unit 20 moves the reflecting mirror 12 from the retracted position to the operating position. That is, the position angle θ is set to the retracted angle θ ｅ From the operating angle θ ｗ The initial processing also includes clearing the monitored temperature data stored in the storage unit 24.

[0036] In step S11 , the control unit 20 acquires the monitored temperature from the temperature monitoring unit 14 .

[0037] In step S12, the control unit 20 determines whether the monitored temperature acquired in step S11 exceeds an evacuation determination temperature, which is a threshold for determining a temperature abnormality. The evacuation determination temperature is set based on the upper limit of the temperature at which the image projection unit 11 can operate normally. Specifically, the evacuation determination temperature may be appropriately determined depending on the specifications of the image projection unit 11 being used, and may be, for example, the rated upper limit temperature of the image projection unit 11, for example, 105°C. The evacuation determination temperature may be determined with a margin relative to the rated upper limit temperature, for example, 95°C. If the determination is negative, the process proceeds to step S13, and if the determination is positive, the process proceeds to a temperature abnormality processing subroutine.

[0038] In step S13, the control unit 20 determines whether or not an end instruction has been received from the HCU 40 for the image projection device 10. If the determination is affirmative, the process proceeds to step S16, and if the determination is negative, the process proceeds to step S14.

[0039] In step S14, the control unit 20 acquires an operation instruction for the image projection device 10 (HUD) from the HCU 40. The operation instruction for the image projection device 10 is, for example, an instruction on the display content of the image projection device 10 from the driver.

[0040] In step S15, the control unit 20 controls the image projection unit 11 so that the image display light GL is projected onto the driver's eye box.

[0041] In step S16, the control unit 20 controls the image projection unit 11 to stop projection of the image display light GL.

[0042] In step S17, the control unit 20 controls the drive unit 13 (motor 13a) to move the reflecting mirror 12 to the retracted position. By retracting the reflecting mirror 12 to the retracted position, sunlight SL can be prevented from irradiating the image projection unit 11 when the image projection device 10 is not in operation. Thereafter, the reflecting mirror drive program is terminated.

[0043] The temperature abnormality processing subroutine will be described with reference to Fig. 5. This subroutine is a program that mainly performs processing to wait until the temperature of the image projection unit 11, which has once become abnormally high, drops to a normal temperature.

[0044] In step S20, the control unit 20 controls the image projection unit 11 to stop projection of the image display light GL.

[0045] In step S21, the control unit 20 controls the drive unit 13 (motor 13a) so that the reflecting mirror 12 moves to the retracted position.

[0046] In step S22, the control unit 20 determines whether or not an end instruction has been received from the HCU 40 for the image projection device 10. If the determination is negative, the process proceeds to step S23, and if the determination is positive, the reflecting mirror driving program is terminated.

[0047] In step S23, the control unit 20 acquires the monitored temperature from the temperature monitoring unit 14.

[0048] In step S24, the control unit 20 determines whether the monitored temperature acquired in step S23 is equal to or lower than a return judgment temperature for judging whether to return to the main routine. If the judgment is negative, the process returns to step S22, and if the judgment is positive, the process proceeds to step S25. There are no particular restrictions on the value of the return judgment temperature, but it is preferable to set the value to a temperature sufficiently lower than the evacuation judgment temperature, for example, room temperature, in order to confirm that the temperature of the image projection unit 11 has dropped sufficiently.

[0049] In step S25, the control unit 20 changes the position of the reflecting mirror 12 from the retracted position to the operating position. That is, the position angle θ is changed to the retracted angle θ ｅ From the operating angle θ ｗ Then, the process returns to the main routine, because the temperature of the image projection unit 11 has returned to the normal temperature range, and the image projection device 10 is then put into normal operation.

[0050] As described above in detail, the image projection device and image projection method according to this embodiment can provide an image projection device and image projection method that have a simple configuration and can effectively suppress the temperature rise of the image irradiation section due to external light.

[0051] Second Embodiment An image projection device and an image projection method according to this embodiment will be described with reference to FIG. 6 . This embodiment differs from the above embodiment in that it takes into consideration eyebox position adjustment. For a driver to properly view a projected image (virtual image) using the image projection device 10, the driver's viewpoint (eye point) must be located within the eyebox. The eyebox is the visible range in a two-dimensional space within which the driver can view the virtual image of the projected image. The eyebox is determined by the characteristics of the optical system of the image projection device 10 (the reflector 12 in this embodiment). In other words, for the driver to view the virtual image of the projected image, the image display light GL must be irradiated onto the windshield in the driver's line of sight. The irradiation position and irradiation angle of the image illumination light GL onto the windshield are primarily determined by the characteristics of the optical system of the image projection device 10. In other words, the range within which the driver can view the virtual image of the projected image is determined by the reflector 12 of the image projection device 10.

[0052] On the other hand, since the position of the viewpoint changes depending on the height of the driver, it may be necessary to adjust the position of the eye box depending on the driver. As described above, the eye box position adjustment is performed by adjusting the operating angle θ of the reflecting mirror 12. ｗ In this embodiment, the adjustment of the eye box position, that is, the operating angle θ ｗ This embodiment takes into consideration the adjustment of the image projection light GL. After receiving notification from the control unit 20 that the reflecting mirror 12 has been set to the operating position, the HCU 40 sends an instruction to the control unit 20 to start emitting the image projection light GL from the image projection unit 11. If the travel time from the retracted position to the operating position is unknown, the HCU 40 must wait until the image projection unit 11 starts operating, allowing a margin for the expected travel time. In other words, the main purpose of this embodiment is to reduce the wasted wait time caused by the HCU 40. Note that the configuration of the image projection device according to this embodiment is similar to the configuration of the image projection device 10 according to the above embodiment, and therefore detailed description thereof will be omitted and reference will be made to FIG. 1 if necessary.

[0053] Referring to FIG. 6 , the operational position adjustment process executed in the image projection device 10 according to this embodiment will be described. FIG. 6 is a flowchart showing the processing flow of an operational position adjustment program that describes the operational position adjustment process. The operational position adjustment program is stored in a storage device such as a ROM (not shown), read by the CPU, and deployed to a RAM or the like for execution. In the flowchart shown in FIG. 6 , it is assumed that an instruction to start operation has already been sent from the HCU 40 to the control unit 20. The operational position adjustment process is executed, for example, when the driver inputs an instruction to adjust the position of the projected image via a UI (User Interface) of the HCU 40. The operational position adjustment program may be executed as an initial process of the reflecting mirror drive program shown in FIG. 4 . In this case, the operational position adjustment program may be incorporated into the initial process of step S10. Before the flowchart shown in FIG. 6 is executed, the reflecting mirror 12 is in the retracted position, and the position angle θ is the retraction angle θ ｅ It is as follows.

[0054] In step S30, the control unit 20 acquires position information of the eyebox from the HCU 40. This position information of the eyebox is set, for example, by the driver via the UI of the HCU 40 while checking the image projected by the image projection device 10. Alternatively, the position information of the eyebox may be automatically set by detecting the driver's viewpoint (eye point) using an imaging device or the like.

[0055] In step S31, the control unit 20 calculates the operating angle θ based on the position information of the eye box acquired in step S30. ｗ Calculate.

[0056] In step S32, the control unit 20 determines the retraction angle θ ｅ and operating angle θ ｗ The difference angle θ ｄ =(θ ｅ -θ ｗ In this embodiment, the retreat area LA is set above the image projection unit 11. ｄ >0, but when the retreat area LA is set below the image projection unit 11, θ ｄ <0.

[0057] In step S33, the control unit 20 calculates the difference angle θ calculated in step S32. ｄ Based on the operation time t ｗ The operation time t ｗ is the angle θ at which the reflecting mirror 12 is retracted. ｅ The operating angle θ after setting ｗ The time required to rotate the motor to the position indicated by the arrow t ｗ For example, the difference angle θ ｄ and operating time t ｗ The difference angle θ ｄ and operating time t ｗ 1 shows a differential angle vs. operation time comparison table, which is an example of the relationship data. This differential angle vs. operation time comparison table may be stored in advance in the storage unit 24. Note that the retraction angle θ ｅ If you want to set a fixed value, the operating angle θ ｗ and operating time t ｗ From the relationship between the operating time t ｗ In this embodiment, the operation time is acquired by referring to the angle difference vs. operation time comparison table. However, the present invention is not limited to this. For example, the angle difference θ ｄ Alternatively, it may be calculated from the rotation speed of the motor 13a.

[0058] In step S34, the control unit 20 counts the operation time t ｗ Count the number.

[0059] In step S35, the control unit 20 determines the operation time t ｗ If the determination is negative, the process returns to step S34 to continue counting the counter, and if the determination is positive, the process proceeds to step S36.

[0060] In step S36, the control unit 20 notifies the HCU 40 that the setting of the reflecting mirror 12 to the operational position has been completed, and then ends the actual operational position adjustment program.

[0061] As described above in detail, the image projection device and image projection method according to the present embodiment can also provide an image projection device and image projection method that can effectively suppress a temperature rise in the image irradiation unit due to external light with a simple configuration. According to the image projection device and image projection method according to the present embodiment, the HCU 40 can obtain information that the position of the reflecting mirror 12 has been set to the operating position, for example, in the initial processing, which has the effect of reducing wasted waiting time before image projection by the image projection device 10.

[0062] This international application claims priority based on Japanese Patent Application No. 2023-117584, filed on July 19, 2023, the entire contents of which are incorporated herein by reference.

[0063] The above descriptions of specific embodiments of the present invention have been presented for purposes of illustration. They are not intended to be exhaustive or to limit the invention to the precise forms described. Numerous modifications and variations will be apparent to those skilled in the art in light of the above description.

[0064] REFERENCE SIGNS LIST 10...Image projection device 11...Image irradiation unit 12...Reflector 13...Drive unit 13a...Motor 13b...Rotation mechanism 14...Temperature monitoring unit 20...Control unit 21...Processing unit 22...Drive signal generation unit 23...Image signal generation unit 24...Storage unit 30...Housing 31...Light-transmitting unit 40...HCU D, LD...Rotation direction h...Horizontal line LA...Retreat area GL...Image display light SL...Sunlight SA1, SA2...Irradiation area θ...Position angle θ ｗ …Operating angle θ ｅ …Retraction angle

Claims

1. An image projection device that projects a virtual image via a display unit, comprising: an image irradiation unit that irradiates image display light to form the virtual image; and a reflection unit that directs the image display light to the display unit, and is characterized in that, when a predetermined condition is satisfied, the orientation of the reflection unit is changed so that light that is incident on the reflection unit from the direction of the display unit is not incident on the image irradiation unit.

2. An image projection device according to claim 1, characterized in that the light incident on said reflecting section from the direction of said display section is sunlight.

3. An image projection device as described in claim 2, wherein the reflecting section has two positions set therein: an operating position where the image display light is guided to the display section, and a retracted position where light incident on the reflecting section from the direction of the display section is not allowed to be incident on the image irradiation section; and further comprising: a temperature monitoring section for monitoring the temperature of the image irradiation section; a drive section for rotating the reflecting section in a vertical plane around a rotation axis; and a control section for controlling the drive section to change the position of the reflecting section from the operating position to the retracted position when the temperature monitored by the temperature monitoring section exceeds a predetermined retraction judgment temperature.

4. An image projection device as described in claim 3, characterized in that the control unit further controls the position of the reflection unit to change from the operating position to the retracted position when an instruction to end operation of the image projection device is received.

5. An image projection device as described in claim 3, characterized in that the control unit stops the irradiation of image display light in the image irradiation unit prior to changing the position of the reflection unit from the operating position to the retracted position.

6. An image projection device as described in claim 3, characterized in that, when the monitoring temperature becomes equal to or lower than a predetermined return judgment temperature after the reflection unit has temporarily retreated to the retreat position, the control unit changes the position of the reflection unit from the retreat position to the operating position and resumes irradiation of the image display light by the image irradiation unit.

7. An image projection device as described in claim 3, characterized in that when the operating position is changed by adjusting the position of an eye box formed by reflection of the image display light on the display unit, the control unit stops irradiating the image display light in the image irradiation unit and waits for the time it takes to move from the retracted position to the changed operating position.

8. An image projection method using an image projection device that projects a virtual image via a display unit, the image projection device comprising: an image irradiation unit that irradiates image display light to form the virtual image; and a reflection unit that directs the image display light to the display unit, the image projection method being characterized in that, when a predetermined condition is satisfied, the orientation of the reflection unit is changed so that light incident on the reflection unit from the direction of the display unit is not incident on the image irradiation unit.

Images