JPWO2019138914A1 - Virtual image display device and head-up display device - Google Patents

Abstract

The screens (23a, 23b) forming the image, the moving mechanism (23t) for moving the screens (23a, 23b) in a predetermined direction, and the screens (23a, 23b) moving in a predetermined direction. It has a virtual image forming optical system (24) that transforms images sequentially formed during the process to form a virtual image (i2) at a projection distance corresponding to the position of the screen (23a, 23b) on the optical axis. , A virtual image display device capable of displaying a virtual image (i2) substantially simultaneously at a plurality of projection distances for each position of an actual object, and a head-up display device.

Description

The present invention relates to a virtual image display device and a head-up display device.

Conventional head-up displays (hereinafter, also referred to as "HUD") generally generate a virtual image at a position separated from the driver by a certain distance, and the display contents by the HUD are vehicle speed and car navigation information. Was limited to. However, in the first place, the purpose of mounting the HUD on a vehicle is to support safer driving by minimizing the movement of the driver's line of sight, but in the sense of safe driving support, display contents such as vehicle speed etc. It's not enough. For example, a system that detects a vehicle, a pedestrian, an obstacle, etc. in front with a camera or a sensor and causes the driver to detect a danger in advance through the HUD to prevent an accident is more preferable. In order to realize such a system, it is conceivable to superimpose a danger signal as a virtual image on a see-through image that is a target for detecting danger of a car, a person, an obstacle, or the like.

When displaying such a virtual image, the distance to the object for detecting danger is not constant. For example, if a danger signal is displayed and superimposed on a virtual image that can be seen 2 m ahead with respect to a danger 50 m ahead, there is a problem that the human eye feels uncomfortable because the focal position is different. As a method for solving such a problem, it is conceivable to superimpose a virtual image on an appropriate position in the depth direction with respect to the real thing.

As described above, as a method for giving depth to the virtual image, in the HUD disclosed in Patent Document 1, a scanning type image forming means such as a MEMS (Micro Electro Mechanical Systems) mirror, a diffusion screen, a projection means, and a diffusion screen It is equipped with a movable means for changing the position of the virtual image, and the distance of the virtual image is changed by changing the position of the diffusion screen. As a result, in view of the fact that the distance that humans gaze at changes with the speed of the vehicle, the virtual image position is moved closer or further away to reduce the movement of the driver's line of sight.

Japanese Unexamined Patent Publication No. 2009-150947

However, as in Patent Document 1, when the position of the virtual image is uniformly moved away from or closer to the speed during driving, the real thing is when the driver moves his face laterally to shift the position of his eyes. There is a problem that the position of the driver and the position of the virtual image such as the danger signal are displaced, and the driver may misidentify the danger signal.

The present invention has been made to solve such a problem, and provides a virtual image display device and a head-up display device capable of displaying a virtual image at a plurality of projection distances at a plurality of projection distances substantially simultaneously at each actual position. The purpose is to do.

The above object of the present invention is solved by the following means.

(1) A screen forming an image, a moving mechanism for moving the screen in a predetermined one direction, and the image sequentially formed while the screen is moving in the predetermined one direction are converted. , A virtual image display device comprising a virtual image forming optical system that forms a virtual image at a projection distance corresponding to the position of the screen on the optical axis.

(2) The moving mechanism is a belt rotating mechanism in which an endless belt is hung on at least two rollers and the belt is rotated by the rotation of the rollers, and is installed perpendicular to the surface of the belt. The virtual image display device according to (1) above, wherein the screen is moved in the predetermined one direction on the optical axis by rotation of the belt.

(3) The moving mechanism has a plurality of the screens, and the moving mechanism moves the plurality of screens vertically installed on the surface of the belt so as to be separated from each other by the rotation of the belt, thereby moving in the predetermined one direction. From the screen that moves any one of the screens to the predetermined one direction and reaches from the roller side at one end of the belt rotation mechanism to the roller side at the other end, a direction other than the predetermined one direction. The virtual image display device according to (2) above, which moves to and switches to another screen that has reached the roller side at one end of the belt.

(4) The screen further includes a display element and a projection optical system that magnifies and projects the image displayed on the display element, and the screen is a diffusion screen that forms the image by being projected. , The virtual image display device according to any one of (1) to (3) above.

(5) The moving mechanism is provided with an outer cylinder having two spiral grooves extending spirally along the side surface while penetrating the side surface, and the two spiral grooves provided at the upper and lower ends of the screen, respectively. A helicoid that moves the screen in the spiral groove along the spiral groove by rotating the outer cylinder around the central axis in the engaged state, and translates the screen in the predetermined one direction in the outer cylinder. The virtual image display device according to (1) above, which is a helixoid mechanism having a pin.

(6) The moving speed measuring unit for measuring the moving speed of the screen in the predetermined one direction, the motor for driving the roller, and the measured moving speed so as to be within a predetermined threshold range. The virtual image display device according to (2) or (3) above, further comprising a control unit for controlling the rotation speed of the motor.

(7) The virtual image display device according to any one of (1) to (6) above, and the object detection unit that detects an object existing in the detection area and determines the distance to the object are determined. A head-up display device including a control unit that causes the virtual image display device to form a virtual image at the projected distance corresponding to the distance to the object.

While the screen forming the image is moved in a predetermined direction, the images sequentially formed are converted to form a virtual image at a projection distance corresponding to the position of the screen on the optical axis. As a result, virtual images can be displayed at a plurality of projection distances at substantially the same time for each actual position.

It is the schematic which looked at the state which mounted the head-up display device in a vehicle from the side. It is the schematic which looked at the vehicle equipped with the head-up display device from the inside. It is a schematic diagram which shows the structure of the virtual image display device. It is a block diagram which shows the hardware structure of the arithmetic control system of a head-up display device. It is a perspective view for demonstrating the display state of a virtual image. It is a schematic diagram for demonstrating the operation which moves a diffusion screen in a specific direction by a helicoid mechanism. It is a schematic diagram for demonstrating the operation which moves a diffusion screen in a specific direction by a helicoid mechanism.

Hereinafter, the virtual image display device and the head-up display device according to the embodiment of the present invention will be described with reference to the drawings. In the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted. The dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios. In the drawings, the vertical direction is the Z direction, the direction parallel to the traveling direction of the vehicle is the Y direction, and the direction orthogonal to these Z and Y directions is the X direction when the virtual image display device is mounted on the vehicle.

(First Embodiment)
FIG. 1 is a schematic view of a state in which the head-up display device is mounted on a vehicle as viewed from the side. FIG. 2 is a schematic view of a vehicle equipped with a head-up display device as viewed from the inside. The user (driver) 900 holds the steering wheel 813 and sits in the driver's seat 816.

The virtual image display device 20 included in the head-up display device 10 displays the image displayed on the display element 21 described later as a virtual image toward the user 900 via the display screen 243.

The configuration other than the display screen 243 of the virtual image display device 20 is arranged so as to be embedded in the dashboard 814 of the vehicle body 811 behind the display 815 such as a car navigation system. The virtual image display device 20 emits a display light D1 corresponding to the virtual image including driving-related information and the like toward the display screen 243. The display screen 243, also called a combiner, is a semitransparent concave mirror or a planar mirror. The display screen 243 is erected on the dashboard 814 by the support at the lower end, and reflects the incident display light D1 toward the rear side (Y direction) of the vehicle body 811. The virtual image display device 20 shown is a stand-alone type in which the display screen 243 is installed separately from the front window 812. The display light D1 reflected by the display screen 243 is guided to the pupil 910 of the user 900 sitting in the driver's seat 816 and the eye box (not shown) corresponding to the peripheral position thereof. The user 900 can observe the display light D1 reflected by the display screen 243, that is, the virtual image i2 as a display image separated by a predetermined distance as if it were in front of the vehicle body 811. On the other hand, the user 900 can observe the outside light transmitted through the display screen 243, that is, the front view, the real image of the automobile, and the like. As a result, the user 900 can observe the virtual image i2 formed by the reflection of the display light D1 on the display screen 243 on the external world image behind the display screen 243, that is, the see-through image.

FIG. 3 is a schematic view showing the configuration of the virtual image display device.

The virtual image display device 20 includes a display element 21, a projection optical system 22, an imaging device 23, a virtual image forming optical system 24, an imaging device driving unit 25, a display control unit 26, and a housing 27. The imaging device 23 includes diffusion screens 23a and 23b, and a belt rotation mechanism 23t. The diffusion screens 23a and 23b constitute a screen. The belt rotation mechanism 23t constitutes a movement mechanism. The virtual image forming optical system 24 includes mirrors 241, 242, and a display screen 243. A component of the virtual image display device 20 other than the display screen 243 is housed in the housing 27.

The optical axis AX that passes through the display element 21, the projection optical system 22, and the imaging device 23 and reaches the mirror 241 of the virtual image forming optical system 24 is set to the same height in the Z direction.

The display element 21 has a two-dimensional display surface 21a. The image formed on the display surface 21a is magnified by the projection optical system 22 and projected onto one of the two diffusion screens 23a and 23b on the optical axis AX. As a result, an image is formed on the diffusion screens 23a and 23b. At this time, by using the display element 21 capable of two-dimensional display, the switching of the projected image to the diffusion screens 23a and 23b can be performed at a relatively high speed. The display element 21 may be a reflective element such as a DMD (Digital Micromirror Device) or LCOS (Liquid Crystal On Silicon), or a transmissive element such as a liquid crystal. In particular, when DMD is used as the display element 21, it becomes easy to switch images at high speed while maintaining brightness, and a virtual image i2 is formed. The projection distance from the user 900 (hereinafter referred to as "virtual image distance"). ) Is advantageous for display that changes. The display element 21 forms an image at a frame rate sufficient to display at a sufficient frame rate for each virtual image distance to be displayed. For example, it operates at a frame rate of 30 fps or more, preferably 90 fps at each virtual image distance. This makes it easy to make it appear that a plurality of virtual images i2 are displayed at the same time at different virtual image distances.

The projection optical system 22 is a fixed focus lens system and has a plurality of lenses (not shown). The projection optical system 22 magnifies and projects the image formed on the display surface 21a of the display element 21 onto the diffusion screens 23a and 23b on the optical axis AX as an intermediate image i1 at an appropriate magnification. As a result, of the two diffusion screens 23a and 23b, the projected intermediate image (image) i1 is formed on the diffusion screen (for example, 23a) on the optical axis AX. The formation of the intermediate image i1 on the diffusion screens 23a and 23b is premised on the display operation of the display element 21. The projection optical system 22 has an aperture 221 arranged on the diffusion screens 23a and 23b of the projection optical system 22. By arranging the aperture 221 in this way, it becomes relatively easy to set and adjust the F number on the diffusion screens 23a and 23b of the projection optical system 22.

The belt rotation mechanism 23t of the imaging device 23 has columnar rollers R1 and R2 arranged at one end and the other end on both end sides, and an endless belt B hung on these rollers R1 and R2, respectively. .. Two diffusion screens 23a and 23b are installed on the surface of the belt B so as to be perpendicular to the surface of the belt B and separated from each other. As the belt B rotates, one of the two diffusion screens 23a and 23b (for example, 23a) is parallel to a predetermined direction (hereinafter, referred to as "specific direction") on the optical axis AX indicated by the solid arrow. It moves, and the other (for example, 23b) moves in a direction other than the specific direction (the direction indicated by the broken line arrow). When either one of the diffusion screens 23a and 23b moves in a specific direction and reaches the other end e1 of the belt B from the other end e2, and the other moves in a direction other than the specific direction and reaches the one end e1 of the belt B. , The diffusion screens 23a and 23b that move in a specific direction are switched. That is, the diffusion screens 23a and 23b moving on the optical axis AX are switched from one of the diffusion screens 23a and 23b to the other. When the diffusion screens 23a and 23b are conveyed in a specific direction by the belt B, the diffusion screens 23a and 23b have a rotation axis on the same plane as the rotation axes of the rollers R1 and R2 in order to make the movement of the diffusion screens 23a and 23b smooth. , Carrier rollers that rotate dependently on rollers R1 and R2 may be used.

The diffusion screens 23a and 23b are diffusion plates for controlling the light distribution angle to a desired angle, and the intermediate image i1 at the imaging position (that is, within the depth of focus at or near the planned imaging position of the intermediate image i1). To form. As a result, by moving the diffusion screens 23a and 23b in the optical axis AX direction, the position of the intermediate image i1 also moves in the optical axis AX direction. As the diffusing screens 23a and 23b, for example, frosted glass, a lens diffusing plate, and a microlens array can be used.

The imaging device drive unit 25 includes a motor 251 and an encoder 252. The imaging device drive unit 25 rotates the rotation axes of the rollers R1 and R2 by the motor 251 to rotate the rollers R1 and R2 at a constant rotation speed. As a result, as the belt B rotates, one of the two diffusion screens 23a and 23b moves in a specific direction on the optical axis AX at a predetermined moving speed, and the other moves in a direction other than the specific direction. The encoder 252 may be composed of a slit disk (not shown) connected to the drive shafts of the rollers R1 and R2, and a photosensor (not shown) that detects light passing through the slit of the slit disk. The light passing through the slit per unit time corresponds to the rotation speed of the rollers R1 and R2. Therefore, the encoder 252 outputs a signal including information on the rotation speeds of the rollers R1 and R2. The output of the encoder 252 is transmitted to the display control unit 26, and is used for measuring the moving speed of the diffusion screens 23a and 23b moving in a specific direction, as will be described later.

The virtual image distance can be changed by moving the diffusion screens 23a and 23b in a specific direction along the optical axis AX by the imaging device driving unit 25. In this way, by changing the position of the projected virtual image i2 and making the display content according to the position, the virtual image i2 is changed while changing the virtual image distance, and as a series of projected images. The virtual image i2 of can be made three-dimensional. Here, the moving range of the diffusion screens 23a and 23b along the optical axis AX in a specific direction is the planned imaging position of the intermediate image i1 or its vicinity, but the focus on the diffusion screens 23a and 23b side of the projection optical system 22. It is desirable to keep it within the depth range. As a result, the virtual image i2 can be formed in a relatively well-focused state.

The moving speed of the diffusion screens 23a and 23b in a specific direction is set to a speed at which the virtual images i2 can be displayed at a plurality of places or at a plurality of distances at the same time. For example, assuming that the virtual image i2 is projected sequentially in three stages of long distance, medium distance, and short distance, when the display element 21 displays at a frame rate of 90 fps, the virtual image i2 at each distance is displayed at 30 fps. Will be switched. As a result, the human eye recognizes that the long-distance, medium-distance, and short-distance virtual images i2 are performed in parallel, and the switching is continuous. As is clear from the above, the movement of the diffusion screens 23a and 23b is controlled so as to be synchronized with the display operation of the display element 21.

The virtual image forming optical system 24 magnifies the intermediate image i1 formed on the diffusion screens 23a and 23b in cooperation with the display screen 243 to form the virtual image i2 in front of the user 900. The virtual image forming optical system 24 is composed of at least one mirror, but includes two mirrors 241 and 242 in the illustrated example.

The display control unit 26 controls the display element 21 and the imaging device drive unit 25. As a result, the timing of forming the intermediate image i1 on the diffusion screens 23a and 23b is controlled, and the three-dimensional virtual image i2 whose virtual image distance changes is sequentially displayed behind the display screen 243. When the position of the intermediate image i1, that is, the positions of the diffusion screens 23a and 23b are close to the virtual image forming optical system 24 on the optical axis AX, the virtual image distance becomes small. On the contrary, when the positions of the diffusion screens 23a and 23b are far from the virtual image forming optical system 24 on the optical axis AX, the virtual image distance becomes large.

The display control unit 26 forms an image on the display element 21 according to the positions of the diffusion screens 23a and 23b. Specifically, an image corresponding to a short-distance virtual image distance is formed on the display element 21 when the positions of the diffusion screens 23a and 23b are close to the virtual image forming optical system 24 on the optical axis AX. On the contrary, an image corresponding to a long-distance virtual image distance is formed on the display element 21 when the positions of the diffusion screens 23a and 23b are far from the virtual image forming optical system 24 on the optical axis AX. The images formed on the diffusion screens 23a and 23b are converted by the virtual image forming optical system 24 and formed as a virtual image i2 at a virtual image distance corresponding to the positions of the diffusion screens 23a and 23b on the optical axis AX.

More specifically, the display control unit 26 sequentially displays images according to the positions of the diffusion screens 23a and 23b while the diffusion screens 23a and 23b are being moved in a specific direction (a predetermined direction). To form. That is, for example, when the diffusion screens 23a and 23b move in a specific direction, the distances between the diffusion screens 23a and 23b and the virtual image forming optical system 24 become short distances, medium distances, and long distances, and the distances correspond to these distances. Images are sequentially formed on the display element 21. Therefore, an image corresponding to the virtual image distance is always formed on the display element 21 in the order of the image corresponding to the virtual image distance of the short distance, the medium distance, and the long distance. As a result, the order of the images formed on the display element 21 according to the positions of the diffusion screens 23a and 23b (that is, the virtual image distance) becomes constant, so that the control of the display order of the images formed on the display element 21 is simplified. it can. Further, the intermediate image i1 formed on the diffusion screens 23a and 23b while the diffusion screens 23a and 23b move in a specific direction is displayed as a virtual image i2. As a result, the fluctuation in the moving speed of the diffusion screens 23a and 23b moving in a specific direction becomes smaller than in the case where the diffusion screens 23a and 23b are reciprocated, so that the movement speed of the diffusion screens 23a and 23b varies. Fluctuations in the frame rate of the virtual image i2 can be suppressed.

The display control unit 26 receives the output of the encoder 252 from the imaging device drive unit 25. As described above, the output of the encoder 252 includes information on the rotation speeds of the rollers R1 and R2 of the belt rotation mechanism 23t. The display control unit 26 calculates the rotation speeds of the rollers R1 and R2 based on the output of the encoder 252, and calculates the movement speeds of the diffusion screens 23a and 23b from the rotation speeds of the rollers R1 and R2. Measure. The display control unit 26 feedback-controls the rotation speed of the motor 251 that drives the rollers R1 and R2 so that the moving speeds of the diffusion screens 23a and 23b are within a predetermined threshold range. The predetermined threshold range is determined based on the frame rate of the display element 21 and the specifications of the fluctuation range set in the frame rate.

By arranging the diffusion screens 23a and 23b that can move on the optical axis AX in this way, not only can the intermediate image i1 that can move in the optical axis AX direction be formed, but also the viewing angle and eyebox size can be secured. , The light utilization efficiency of the optical system can be increased. If the light distribution angle of the diffusion by the diffusion screens 23a and 23b is made too large, the F value of the virtual image forming optical system 24 needs to be reduced in order to increase the light utilization efficiency, so that the depth of focus becomes shallow and the display becomes shallow. It should be noted that the possible distance range is narrowed.

FIG. 4 is a block diagram showing a hardware configuration of an arithmetic control system of a head-up display device. In addition to the virtual image display device 20 described above, the head-up display device 10 includes a driver detection unit 71, an environment monitoring unit 72, and a main control unit 60. The environment monitoring unit 72 constitutes an object detection unit.

The main control unit 60 controls the entire head-up display device 10 to three-dimensionally display the virtual image i2 corresponding to objects such as oncoming vehicles and pedestrians.

The driver detection unit 71 is a part that detects the presence or viewpoint position of the user 900 in the vehicle 800, and has an internal camera 71a directed toward the driver's seat 816, an image processing unit 71b for the driver's seat, and a determination unit 71c. .. The internal camera 71a is installed on the dashboard 814 in the vehicle body 811 facing the driver's seat 816 (see FIG. 2), and takes an image of the head of the user 900 sitting in the driver's seat 816 and its surroundings. To do. The driver's seat image processing unit 71b performs various image processing such as brightness correction on the image captured by the internal camera 71a, and facilitates the processing by the determination unit 71c. The determination unit 71c detects the head and eyes (pupil 910) of the user 900 by extracting or cutting out an object from the driver's seat image processed by the driver's seat image processing unit 71b, and accompanies the driver's seat image. From the depth information to be processed, the presence or absence of the head of the user 900 in the vehicle body 811 and the spatial position of the eyes of the user 900 (resulting in the direction of the line of sight) are calculated.

The environment monitoring unit 72 identifies objects such as automobiles, bicycles, and pedestrians that are close to the front, and determines the distance to the objects. The environment monitoring unit 72 includes an external camera 72a, an external image processing unit 72b, and a determination unit 72c. The external camera 72a is installed at an appropriate position inside and outside the vehicle body 811 and captures external images such as the front and side of the user 900 or the vehicle 800. The external image processing unit 72b performs various image processing such as brightness correction on the image captured by the external camera 72a, and facilitates the processing by the determination unit 72c. The determination unit 72c detects the existence and size of objects such as automobiles, bicycles, and pedestrians by extracting or cutting out objects from the external image processed by the external image processing unit 72b, and accompanies the external image. The spatial position of the object in front of the vehicle 800 is calculated from the depth information.

The internal camera 71a and the external camera 72a include, for example, a compound eye type three-dimensional camera. That is, both cameras 71a and 72a are a matrix of camera elements in which a lens for imaging, a CMOS (Complementary Metal-Oxide Sensor) sensor, and other image pickup elements are arranged in a matrix. It has a drive circuit for each. The plurality of camera elements constituting the cameras 71a and 72a are, for example, focused on different positions in the depth direction, or can detect relative parallax, and are obtained from each camera element. By analyzing the state of the image (focus state, position of the object, etc.), the distance to each area in the image or the object is determined.

In addition, instead of or together with the compound eye type cameras 71a and 72a as described above, a combination of a two-dimensional camera and an infrared distance sensor may be used. As a result, it is possible to obtain distance information in the depth direction for each part in the captured screen. Further, instead of the compound eye type cameras 71a and 72a, a stereo camera in which two two-dimensional cameras are separately arranged can obtain distance information in the depth direction with respect to each part (area or object) in the captured screen. In addition, with a single two-dimensional camera, distance information in the depth direction may be obtained for each part in the captured screen by performing imaging while changing the focal length at high speed.

Further, instead of the compound eye type external camera 72a, LIDAR (Light Detection And Ringing) technology may be used. As a result, distance information in the depth direction can be obtained for each part (area or object) in the detection area. With the LIDAR technology, it is possible to measure scattered light for pulsed laser irradiation, measure the distance and extent to an object at a long distance, and acquire information on the distance to an object in the field of view and information on the extent of the object. By combining radar sensing technology such as this LIDAR technology with technology for detecting the distance of an object from image information, the detection accuracy of the object can be improved.

The display control unit 26 operates the virtual image display device 20 under the control of the main control unit 60 to display a three-dimensional virtual image i2 whose virtual image distance changes behind the display screen 243. The display control unit 26 generates a virtual image i2 to be displayed on the virtual image display device 20 based on information including the distance and size of the object received from the environment monitoring unit 72 via the main control unit 60. The virtual image i2 is, for example, a frame F (see FIG. 5) located around the car, bicycle, pedestrian, or other object OB (see FIG. 5 described later) existing behind the display screen 243 in the depth position direction thereof. It becomes a sign like.

The display control unit 26 receives a detection output regarding the presence of the user 900 and the position of the eyes from the driver detection unit 71 via the main control unit 60. This makes it possible to automatically start and stop the projection of the virtual image i2 by the virtual image display device 20. It is also possible to project the virtual image i2 only in the direction of the line of sight of the user 900. Further, it is possible to perform projection with emphasis such as brightening or blinking only the virtual image i2 in the direction of the line of sight of the user 900.

FIG. 5 is a perspective view for explaining the display state of the virtual image. The front of the user 900, who is the driver, is a detection area DF corresponding to the observation field of view. Within the detection area DF, that is, in and around the road, there are objects OB1 and OB3 of a person such as a pedestrian, and objects OB2 of a moving object such as an automobile. In this case, the main control unit 60 of the head-up display device 10 projects a three-dimensional virtual image i2 (i21 to i23) by the virtual image display device 20, and serves as a related information image for each object OB1, OB2, OB3. Frames F1, F2, and F3 are added. At this time, since the distances from the user 900 to the objects OB1, OB2, and OB3 are different, the environment monitoring unit 72 determines the virtual image distances of the virtual images i21, i22, and i23 for displaying the frames F (F1, F2, F3). It corresponds to the distance from the user 900 or the vehicle 800 to each object OB1, OB2, OB3. The projected distances of the virtual images i21, i22, and i23 are discrete and may not exactly match the actual distances to the objects OB1, OB2, and OB3. However, if the difference between the projected distances of the virtual images i21, i22, and i23 and the actual distances to the objects OB1, OB2, and OB3 is not large, parallax is unlikely to occur even if the viewpoint of the user 900 moves (in the X direction). The arrangement relationship between the objects OB1, OB2, OB3 and the frames F1, F2, F3 can be substantially maintained.

(Second Embodiment)
A second embodiment of the present invention will be described. The difference between the present embodiment and the first embodiment is that the imaging device 23 is configured by the diffusion screen 23c and the helicoid mechanism 23t'. Since the present embodiment is the same as the first embodiment in other respects, duplicate description will be omitted or simplified.

6A and 6B are schematic views for explaining the operation of moving the diffusion screen in a specific direction by the helicoid mechanism. In the figure, in order to clarify the moving operation of the diffusion screen 23c, only the portion visible from the front surface (front of the paper) of the diffusion screen 23c, the helicoid pins P1, P2, and the spiral grooves G1 and G2 is shown by a solid line, and other parts are shown. The shape is shown by a broken line.

The helicoid mechanism 23t'has an outer cylinder 23d and helicoid pins P1 and P2 provided at the upper and lower ends of the disc-shaped diffusion screen 23c. The outer cylinder 23d has two spiral grooves G1 and G2 on the side surface. The spiral grooves G1 and G2 each penetrate the side surface of the outer cylinder 23d and extend along the side surface. The helicoid pins P1 and P2 are engaged with the spiral grooves G1 and G2, respectively.

Reference to FIG. 6A shows a state in which the helicoid pins P1 and P2 are engaged with the spiral grooves G1 and G2, respectively, and the diffusion screen 23c is closest to the virtual image forming optical system 24. From this state, when the outer cylinder 23d is rotated in the direction of the solid arrow (forward direction) in the figure around the central axis indicated by the alternate long and short dash line, the helicoid pins P1 and P2 spiral along the spiral grooves G1 and G2, respectively. It moves in the grooves G1 and G2. As a result, the diffusion screen 23c can be translated in the specific direction indicated by the white arrow.

FIG. 6B shows a state in which the diffusion screen 23c moves in a specific direction and is farthest from the virtual image forming optical system 24. In this state, when the outer cylinder 23d is rotated in the direction of the solid arrow in the figure (opposite direction) around the central axis indicated by the alternate long and short dash line, the helicoid pins P1 and P2 spiral along the spiral grooves G1 and G2, respectively. It moves in the grooves G1 and G2. As a result, the diffusion screen 23c can be translated in the direction opposite to the specific direction indicated by the white arrow. When the diffusion screen 23c moves in the direction opposite to the specific direction and comes closest to the virtual image forming optical system 24, the diffusion screen 23c returns to the position shown in FIG. 6A.

The moving speed at which the diffusion screen 23c is moved in the direction opposite to the specific direction can be set to be less than one frame time of the intermediate image i1. That is, the moving speed of the intermediate image i1 is the time from the position where the diffusion screen 23c is farthest from the virtual image forming optical system 24 (the position in FIG. 6B) to the position where the diffusion screen 23c is closest to the virtual image forming optical system 24 (the position in FIG. 6A). It can be set to be less than one frame time. As a result, the virtual image i2 can be formed substantially based only on the intermediate image i1 formed on the diffusion screen 23c while the diffusion screen 23c moves in a specific direction.

The embodiment according to the present invention has the following effects.

While the screen forming the image is moved in a predetermined direction, the images sequentially formed are converted to form a virtual image at a projection distance corresponding to the position of the screen on the optical axis. As a result, virtual images can be displayed at a plurality of projection distances at substantially the same time for each actual position. In addition, it is possible to simplify the control of the image formation order according to the projection distance, and it is possible to suppress the fluctuation of the frame rate of the virtual image by suppressing the fluctuation of the moving speed of the screen.

Further, the moving mechanism of the screen is a belt rotating mechanism in which an endless belt is hung on at least two rollers and the belt is rotated by the rotation of the rollers, and the screen installed perpendicular to the surface of the belt is a belt. Moves in a specific direction by rotating. As a result, the screen can be moved in a specific direction with a simple configuration.

Further, a plurality of screens are vertically installed on the surface of the belt of the belt rotation mechanism so as to be separated from each other. Then, by moving a plurality of screens by rotating the belt, any one screen that moves in a specific direction is moved in a specific direction and reaches from one end to the other end of the belt in a direction other than the specific direction. To switch to another screen that has reached one end of the belt. As a result, the time when the screen does not exist on the optical axis can be effectively shortened, and the time when the virtual image is not formed can be suppressed.

Further, a display element and a projection optical system for enlarging the image displayed on the display element and projecting it on the screen are provided, and the screen is used as a diffusion screen. As a result, the moving mechanism of the screen can be simplified.

Further, the moving mechanism of the screen is such that the helicoid pins provided at the upper and lower ends of the screen are engaged with the spiral grooves provided on the side surface of the outer cylinder to rotate the outer cylinder so that the screen can be moved in a specific direction in the outer cylinder. A helicoid mechanism that moves in parallel. As a result, the movement of the screen becomes smoother, and the image quality of the virtual image can be improved.

Further, the moving speed of the screen moving in a specific direction is measured, and the rotating speed of the motor for driving the roller of the belt rotation mechanism is controlled based on the measured moving speed of the screen. Thereby, the accuracy of the virtual image distance of each virtual image can be improved.

The present invention is not limited to the embodiments described above.

For example, instead of the diffusion screen, an LED display, a liquid crystal display, or an organic EL display that forms an image with a plurality of pixels may be used as the screen. As a result, the display element and the projection optical system can be omitted, so that the device can be simplified.

Further, the number of diffusion screens conveyed by the belt rotation mechanism may be one or three or more. The number of rollers on which the belt is hung by the belt rotation mechanism may be three or more.

Further, as the spiral groove of the helicoid mechanism, in addition to the spiral groove for moving the screen in a specific direction, another spiral groove connected to the spiral groove for moving the screen in the opposite direction to the specific direction is provided. May be good. As a result, the screen moved in a specific direction can be returned to the position before the movement without changing the rotation direction of the outer cylinder.

Further, the screen moved in a specific direction by the helicoid mechanism is not limited to a disk shape and may be a square plate shape.

This application is based on a Japanese patent application (Japanese Patent Application No. 2018-002445) filed on January 11, 2018, the disclosure of which is referenced and incorporated as a whole.

10 Head-up display device,
20 Virtual image display device,
21 Display element,
21a display surface,
22 Projection optics,
23 Imaging device,
23a, 23b, 23c diffuse screen,
23d outer cylinder,
23t belt rotation mechanism,
23t'helicoid mechanism,
24 Virtual image formation optical system,
241 and 242 mirrors,
243 display screen,
25 Imaging device drive unit,
26 Display control unit,
27 housing,
60 Main control unit,
71 Driver detector,
72 Environmental Monitoring Department,
800 vehicles,
811 body,
812 front window,
813 handle,
814 dashboard,
815 display,
816 Driver's seat,
900 users,
910 eyes,
AX, AX0, AX1 optical axis,
D1 display light,
DF detection area,
F, F1, F2, F3 frames,
G1, G2 spiral groove,
OB object,
P1, P2 helicoid pins,
i1 intermediate image,
i2, i21, i22, i23 Virtual image.

Claims (7)

The screen that forms the image and
A moving mechanism that moves the screen in a predetermined direction,
A virtual image forming optical system that transforms the images sequentially formed while the screen is moving in a predetermined direction to form a virtual image at a projection distance corresponding to the position of the screen on the optical axis. ,
Virtual image display device having. The moving mechanism is a belt rotation mechanism in which an endless belt is hung on at least two rollers and the belt is rotated by the rotation of the rollers, and the screen installed perpendicular to the surface of the belt is mounted. The virtual image display device according to claim 1, wherein the belt is rotated to move the belt in the predetermined direction on the optical axis. Having multiple screens
The moving mechanism moves a plurality of the screens vertically installed on the surface of the belt so as to be separated from each other by rotation of the belt, thereby moving any one of the screens in a predetermined direction. From the screen that has moved in the predetermined one direction and reached from the roller side at one end of the belt rotation mechanism to the roller side at the other end, it has moved in a direction other than the predetermined one direction and is at the one end of the belt. The virtual image display device according to claim 2, wherein the screen is switched to another screen that has reached the roller side. Display element and
It further has a projection optical system that magnifies and projects the image displayed on the display element.
The screen is a diffusion screen that forms the image when projected.
The virtual image display device according to any one of claims 1 to 3. The moving mechanism is provided in a state in which an outer cylinder having two spiral grooves extending spirally along the side surface while penetrating the side surface and the upper and lower ends of the screen are engaged with the two spiral grooves, respectively. The helicoid pin, which moves the screen in the spiral groove along the spiral groove by rotating the outer cylinder around the central axis and translates the screen in the predetermined direction in the outer cylinder. The virtual image display device according to claim 1, which is a helixoid mechanism having. A moving speed measuring unit that measures the moving speed of the screen in the predetermined direction,
The motor that drives the roller and
A control unit that controls the rotational speed of the motor so that the measured moving speed is within a predetermined threshold range.
The virtual image display device according to claim 2 or 3, further comprising. The virtual image display device according to any one of claims 1 to 6.
An object detection unit that detects an object existing in the detection area and determines the distance to the object,
A control unit that causes the virtual image display device to form a virtual image at the projected distance corresponding to the determined distance to the object.
Head-up display device with.