WO2018124299A1 - Virtual image display device and method - Google Patents

Abstract

Provided are a virtual image display device and method with which it is possible for hazard signals and other additional information, in addition to display contents such as vehicle speed, to be displayed at multiple distances in such a way as to allow appropriate recognition thereof, while having a simple configuration. A virtual image display device 100 is provided with an image forming element 11, which is a display unit, and a virtual image display optical system 30 which enlarges an image formed in a display region by the image forming element 11, wherein an optical path length varying element 16 having a construction with different thicknesses in an optical axis AX direction is disposed in an optical path from the display region to a mirror 17a, which is a first reflective body.

Description

Virtual image display apparatus and method

The present invention relates to a virtual image display device and a virtual image display method in which a virtual image is displayed at the tip of a line of sight and the projection position of the virtual image is variable.

Conventional head-up display (HUD) devices generally generate a virtual image at a position away from a driver by a certain distance, and display contents by HUD are limited to vehicle speed, car navigation information, and the like. It was. In the first place, the purpose of installing the HUD in the car is to support the safer driving by minimizing the movement of the driver's line of sight. It is more preferable to use a system in which, for example, a car, a pedestrian, an obstacle, etc. in front of the vehicle are detected by a camera or a sensor, and the driver is informed of the danger in advance through HUD to prevent an accident. In order to realize such a system, for example, it is conceivable to display a danger signal or other additional information superimposed on a see-through image of a car, a person, an obstacle or the like.

In the system that displays the danger signal superimposed as described above, if the distance from the driver to the virtual image is constant, the actual position and the position of the danger signal will be shifted if the driver's eyes are displaced. Therefore, there is a problem that the driver misidentifies the danger signal. As a technique for solving such a problem, it is conceivable to superimpose a virtual image on the real object including the depth direction.

For example, Patent Document 1 discloses a method of changing a distance from a driver to a virtual image by switching a reflector to be projected by moving a mirror. However, in such a method, there are at most two virtual image positions. As such, it is not sufficient to prevent driver misidentification. Patent Document 2 discloses a method of generating a plurality of virtual images by arranging a plurality of display elements. In such a method, the virtual image distance is reduced due to physical restrictions such as the thickness of the display elements and wiring. It is difficult to make fine adjustments, and there is a concern that the cost may increase due to having a plurality of display elements, and the display control circuit may be complicated.

Japanese Patent Laid-Open No. 6-144082 JP 2004-168230 A

The present invention has been made in view of the above-described background art, and has a simple configuration and can display a virtual image display device capable of displaying additional information as described above at a large number of distances to allow proper recognition. It is another object of the present invention to provide a virtual image display method.

In order to achieve at least one of the above objects, a virtual image display device reflecting one aspect of the present invention includes a display unit and a virtual image display optical system that enlarges an image formed in the display region by the display unit. An optical path length changing element having a structure with different thicknesses in the optical axis direction is arranged in the optical path from the display area to the first reflector.

In order to achieve at least one of the above objects, a virtual image display method reflecting one aspect of the present invention includes a display unit and a virtual image display optical system that enlarges an image formed in the display region by the display unit. In the virtual image display method used, an optical path length changing element having a structure having a different thickness in the optical axis direction is arranged in the optical path from the display region to the first reflector, and the projection distance is set by the arrangement of the optical path length changing element. Change.

FIG. 1A is a side cross-sectional view showing a state in which the virtual image display device of the first embodiment is mounted on a vehicle body, and FIG. 1B is a front view from the vehicle inner side explaining the image display device. It is an expanded side sectional view explaining the specific structural example of a virtual image display apparatus. 3A and 3B are a side sectional view and a front view illustrating the optical path length changing element and the like. 4A and 4B are diagrams for explaining the positional relationship between the virtual image position and the see-through object in the virtual image display device according to the first embodiment. 5A and 5B are diagrams for explaining the positional relationship between a virtual image position and a see-through object in the virtual image display device of the comparative example. It is a block diagram explaining the display system for moving bodies containing a virtual image display apparatus. It is a figure explaining the virtual image display apparatus of 2nd Embodiment. 8A and 8B are a side sectional view and a front view illustrating the optical path length changing element. It is a figure explaining the virtual image display apparatus of 3rd Embodiment. 10A and 10B are a side sectional view and a front view illustrating the optical path length changing element. It is a figure explaining the virtual image display apparatus of 4th Embodiment. It is a figure explaining the virtual image display apparatus of 5th Embodiment. It is a figure explaining the virtual image display apparatus of 6th Embodiment. 14A and 14B are a partially broken side view and a partially broken front view for explaining the structure of the diffusion portion incorporating the intermediate screen. FIG. 15A is a diagram specifically illustrating a change in the position of the functional area, and FIG. 15B is a diagram specifically illustrating a change in the movable projection position of the intermediate image. It is a figure explaining the display zone and distance zone while showing the relationship between the position of an apparent intermediate image, and projection distance. It is a figure explaining the operation example of the virtual image display apparatus of 6th Embodiment. It is a conceptual diagram explaining an example of the display switching in a display zone. It is a figure explaining the virtual image display apparatus of 7th Embodiment. It is a figure explaining the virtual image display apparatus of 8th Embodiment.

[First Embodiment]
Hereinafter, a virtual image display device and method according to a first embodiment of the present invention will be described with reference to the drawings.

1A and 1B are a conceptual side sectional view and a front view illustrating a virtual image display device 100 according to the present embodiment and a use state thereof. The virtual image display device 100 is mounted in the vehicle body 2 as a head-up display device, for example, and includes a drawing unit 10 and a display screen 20. The virtual image display device 100 displays image information displayed on an image forming element 11 (to be described later) in the drawing unit 10 for a driver UN through the display screen 20.

The drawing unit 10 of the virtual image display device 100 is installed so as to be embedded in the dashboard 4 of the vehicle body 2 and emits display light HK corresponding to an image including driving-related information and the like toward the display screen 20. The display screen 20 is a half mirror also called a combiner, and is a concave mirror or a plane mirror having a semi-transmission property. The display screen 20 is erected on the dashboard 4 with the lower end supported, and reflects the display light HK from the drawing unit 10 toward the rear of the vehicle body 2. That is, in the illustrated case, the display screen 20 is an independent type that is installed separately from the windshield 8. The display light HK reflected by the display screen 20 which is a half mirror is guided to an eye box (not shown) corresponding to the pupil HT of the driver UN sitting on the driver's seat 6 and its peripheral position. The driver UN can observe the display light HK reflected by the display screen 20, that is, the display image IM as a virtual image in front of the vehicle body 2. On the other hand, the driver UN can observe external light transmitted through the display screen 20 that is a half mirror, that is, a real image of a front view, a car, and the like. As a result, the driver UN observes a display image (virtual image) IM including operation-related information and the like formed by reflection of the display light HK on the display screen 20 so as to overlap the external image behind the display screen 20. Can do.

As shown in FIG. 2, the drawing unit 10 operates a main body optical system 13 including a magnification image forming system or a projection optical system including an image forming element 11 and a virtual image type reflection optical system, and a main body optical system 13. A display control unit 18 and a housing 14 for housing the main optical system 13 and the like are provided. Among these, the combination of the main body optical system 13 and the display screen (combiner) 20 constitutes a virtual image display optical system 30.

The main body optical system (projection optical system) 13 includes an image forming optical system 15 capable of forming an intermediate image TI obtained by enlarging an image formed on the image forming element 11 in addition to the image forming element 11 serving as a display unit. An optical path length changing element 16 disposed in the latter stage of the optical path in the vicinity of the imaging position of the image TI and a virtual image forming optical system 17 for converting the intermediate image TI into a virtual image are provided.

The image forming element 11 is a display unit having a two-dimensional display surface 11a. The image formed on the display surface 11a of the image forming element 11 is enlarged by the image forming optical system 15 in the main body optical system 13 to form an intermediate image TI, passes through the optical path length changing element 16, and is a virtual image forming optical system. To 17 mag. At this time, by using the image forming element 11 capable of two-dimensional display, the intermediate image TI or the display image (virtual image) IM can be switched at a relatively high speed. The image forming element 11 may be a reflective element such as DMD or LCOS, or a transmissive element such as liquid crystal. In particular, when a DMD is used as the image forming element 11, it becomes easy to switch images at high speed while maintaining brightness, which is advantageous for display in which a virtual image distance or a projection distance is changed. The image forming element 11 operates at a frame rate of 30 fps or higher. This makes it easy to make it appear as if a plurality of display images IM are simultaneously displayed at different projection distances.

The imaging optical system 15 is a fixed-focus lens system, and has a plurality of lenses (not shown). The imaging optical system 15 enlarges and projects an image formed on the display surface 11a of the image forming element (display unit) 11 at an appropriate magnification, and intermediate image TI at a position close to the incident surface 16j of the optical path length changing element 16. Form. The imaging optical system 15 has a stop 15a arranged closest to the optical path length changing element 16 of the imaging optical system 15.

The optical path length changing element 16 is a rotating body formed of resin or glass, and is driven by a rotation driving device 62a provided in the arrangement changing device 62 that is a moving portion and rotates at a constant speed. Although the optical path length changing element 16 will be described in detail later, the optical path length changing element 16 has a plurality of partial areas having different thicknesses. These partial areas are intermediate areas formed by the imaging optical system 15 as the optical path length changing element 16 rotates. Sequentially arranged at the position of the image TI. By moving the optical path length changing element 16 around the optical axis AX by the arrangement changing device 62, the virtual image forming optical system 17 displays the display image IM as a virtual image formed behind the display screen (combiner) 20 and the observer. The distance to a certain driver UN can be increased or decreased. Thus, the display image IM is changed while changing the virtual image distance to the display image IM by changing the position of the projected display image IM forward and backward and by changing the display contents according to the position. As a result, the display image IM as a series of projection images can be made three-dimensional.

Fig. A is a side sectional view for explaining the optical path length changing element 16 and the arrangement changing device 62, and Fig. 3B is a front view for explaining the optical path length changing element 16. The optical path length changing element 16 includes a shaft portion 19a through which a rotation axis RX extending parallel to the optical axis AX passes, and four partial regions 16a to 16d supported by the shaft portion 19a and arranged around the rotation axis RX. . The rotation driving device 62a rotates the optical path length changing element 16 via the shaft portion 19a. The rotation drive device 62a is fixed on a support member 62b having a pedestal and a support column.

The optical path length changing element 16 is a stepped structure including four partial regions 16a to 16d, and is a disk-shaped structure 116 provided with the partial regions 16a to 16d around the center. The optical path length changing element 16 as the disk-like structure 116 has a role of changing the optical path length converted into air in, for example, four stages. Each of the partial areas 16a to 16d constituting the optical path length changing element 16 has a size corresponding to the intermediate image TI formed in the display area. These partial regions 16a to 16d have different thicknesses in the optical axis AX direction. Specifically, the optical path length changing element 16 has a plurality of exit surfaces 16e to 16h arranged stepwise along a circumference 16r through which the optical axis AX passes on the virtual image forming optical system 17 side or the rear stage side of the optical path. Each of the exit surfaces 16e to 16h is a flat surface. That is, in the optical path length changing element 16, the exit surfaces 16e to 16h arranged on the opposite side of the intermediate image TI formed in the display area are stepped. On the other hand, the optical path length changing element 16 has an incident surface 16j that is a single plane on the imaging optical system 15 side or the optical path pre-stage side. The intermediate image TI is formed in a display region from the optical path length changing element 16 to the preceding stage of the optical path. Specifically, the optical path length changing element 16, that is, the incident surface 16j is within ± 1 mm from the imaging position of the intermediate image TI. Has been placed. The incident surface 16j of the optical path length changing element 16 has a diffusion function. The incident surface 16j is processed into a polished glass surface, for example. In this case, a compulsory intermediate image is formed on the incident surface 16j, and light diffuses therefrom, so that a wide eye box can be secured. In addition, the part of the frosted glass surface corresponding to a spreading | diffusion function can be affixed on the entrance plane 16j of the optical path length change element 16 as another component, for example. As another part to be affixed on the incident surface 16j, a polished glass plate, a diffusion plate, a microlens array, or the like can be used.

The optical path length changing element 16 is also rotated around the rotation axis RX by rotating the shaft portion 19a, for example, at a constant speed by the rotation drive device 62a. As a result, the four partial regions 16a to 16d sequentially move on the optical axis AX, and the partial regions 16a to 16d move so as to cross the optical axis AX. At this time, the positional relationship is adjusted and positioned so that the centers of the partial areas 16a to 16d cross the optical axis AX. When the shaft portion 19a rotates in the clockwise direction when viewed from the front, for example, the partial regions 16a to 16d are arranged on the optical axis AX in the order. At the timing when the center of the partial region 16a is arranged on the optical axis AX, the partial region 16a is the thickest, and the image or intermediate image TI displayed on the image forming element 11 which is the display unit at this time is a half mirror. It is displayed as a virtual image closest to the back of a certain display screen (combiner) 20. Further, at the timing when the center of the partial region 16d is arranged on the optical axis AX, the partial region 16d is the thinnest, and the image or intermediate image TI displayed on the image forming element 11 at this time is a half mirror. It is displayed as a virtual image farthest behind the screen (combiner) 20. Here, the apparent position of the intermediate image TI viewed from the virtual image forming optical system 17 is closest to the virtual image forming optical system 17 when the thickest partial region 16a is positioned on the optical axis AX, and the thinnest portion. When the region 16d is positioned on the optical axis AX, it is closest to the display surface 11a of the image forming element 11. The image display on the image forming element 11 is intermittent, like a strobe, and is at the timing when the center or the periphery of the partial areas 16a to 16d is arranged on the optical axis AX. Note that the number of partial regions is not limited to four, and the number of partial regions may be changed according to the number of distances at which a virtual image is desired to be displayed.

The virtual image forming optical system 17 shown in FIG. 2 enlarges the intermediate image TI formed on the optical path length changing element 16 in cooperation with the display screen 20, and forms a display image IM as a virtual image in front of the driver UN. The virtual image forming optical system 17 includes at least one mirror, but in the illustrated example, includes two mirrors 17a and 17b. Here, the one mirror 17a is a first reflector, which is disposed on the intermediate image TI side in the front stage of the optical path, and is a first mirror having optical power. The other mirror 17b is disposed on the display screen (combiner) 20 side in the latter stage of the optical path, and is a second mirror having optical power. In this case, the main body optical system (projection optical system) 13 can be increased in magnification and performance.

FIG. 4A is a conceptual plan view for explaining display by the virtual image display optical system 30 or the virtual image display device 100 of the embodiment, and FIG. 4B is a diagram for explaining how the display corresponding to FIG. 4A is seen. As shown in FIG. 4A, a case will be described in which a display frame HW, which is a display image IM, is formed at or near the position of an object (in this case, an automobile traveling in an oncoming lane) KT that is being observed by the driver UN. Such a display frame HW is a danger warning signal or other virtual image, and shows, for example, a result of identifying a car, a bicycle, a pedestrian, or the like that is close to the front. In this case, since the display frame HW projects the display frame HW in the vicinity of the object KT as shown in FIG. 4A, as shown in FIG. 4B, not only the driver UN at the standard position P0 but also the head The target object KT and the display frame HW are substantially overlapped with each other and the driver UN whose posture is changed to the changed position P1 where the position is moved appears to be substantially free from displacement.

FIG. 5A is a conceptual plan view for explaining display by a virtual image display optical system or a virtual image display device of a comparative example, and FIG. 5B is a diagram for explaining how a display corresponding to FIG. 5A is seen. As shown in FIG. 5A, a case will be described in which the display frame HW that is the display image IM is formed at a fixed position regardless of the object KT that the driver UN observes. In this case, as shown in FIG. 5A, since the display frame HW is projected substantially in front of the object KT, as shown in FIG. 5B, for the driver UN at the standard position P0, the object KT and the display frame HW Even if they appear to be substantially overlapped with each other, the display frame HW appears to be greatly displaced in the lateral direction in which the eyes are aligned with respect to the object KT for the driver UN whose posture has been changed to the change position P1. The possibility of misidentifying the frame HW increases.

FIG. 6 is a block diagram illustrating the moving body display system 200, and the moving body display system 200 includes the virtual image display device 100 as a part thereof. The virtual image display device 100 has the structure shown in FIG. 2, and a description thereof is omitted here. A moving body display system 200 shown in FIG. 6 is incorporated in an automobile or the like that is a moving body.

The moving body display system 200 includes a driver detection unit 71, an environment monitoring unit 72, and a main control device 90 in addition to the virtual image display device 100.

The driver detection unit 71 is a part that detects the presence and viewpoint position of the driver UN, and includes a driver seat camera 71a, a driver seat image processing unit 71b, and a determination unit 71c. The driver seat camera 71a is installed in front of the driver seat of the dashboard 4 in the vehicle body 2 (see FIG. 1B), and takes images of the head of the driver UN and its surroundings. The driver seat image processing unit 71b performs various types of image processing such as brightness correction on the image captured by the driver seat camera 71a to facilitate processing in the determination unit 71c. The determination unit 71c detects the head and eyes of the driver UN by extracting or cutting out an object from the driver seat image that has passed through the driver seat image processing unit 71b, and detects the vehicle body 2 from the depth information attached to the driver seat image. The spatial position of the eyes of the driver UN (resulting in the direction of the line of sight) is calculated along with the presence or absence of the head of the driver UN.

The environment monitoring unit 72 is a part for identifying a car, a bicycle, a pedestrian, and the like that are close to the front, and includes an external camera 72a, an external image processing unit 72b, and a determination unit 72c. The external camera 72a is installed at appropriate positions inside and outside the vehicle body 2, and captures an external image such as the front or side of the driver UN or the windshield 8. The external image processing unit 72b performs various types of image processing such as brightness correction on the image captured by the external camera 72a to facilitate processing by the determination unit 72c. The determination unit 72c detects the presence / absence of a target KT (for example, see FIG. 4A) such as an automobile, a bicycle, and a pedestrian by extracting or cutting out an object from the external image that has passed through the external image processing unit 72b. The spatial position of the object KT in front of the vehicle body 2 is calculated from the depth information attached to the image.

The driver's seat camera 71a and the external camera 72a are not shown, but are, for example, compound eye type three-dimensional cameras. That is, both cameras 71a and 72a are obtained by arranging camera elements, each of which includes an imaging lens and a CMOS or other image sensor, in a matrix, and each has a drive circuit for the image sensor. The plurality of camera elements constituting each of the cameras 71a and 72a are adapted to focus at different positions in the depth direction, for example, or to detect relative parallax, and are obtained from each camera element. By analyzing the state of the image (focus state, object position, etc.), the distance to each region or object in the image can be determined.

Even if a combination of a two-dimensional camera and an infrared distance sensor is used in place of the compound- eye cameras 71a and 72a as described above, distance information in the depth direction is obtained for each part in the captured screen (dead angle image). Obtainable. In addition, distance information in the depth direction can be obtained for each part (region or object) in the captured screen by using a stereo camera in which two two-dimensional cameras are separately arranged in place of the compound- eye cameras 71a and 72a. In addition, in a single two-dimensional camera, distance information in the depth direction can be obtained for each part in the captured screen by performing imaging while changing the focal length at high speed.

The display control unit 18 operates the virtual image display optical system 30 under the control of the main controller 90, and the three-dimensional display in which the virtual image distance or the projection distance changes behind the display screen (combiner) 20 that is a half mirror. The image IM is displayed. The display control unit 18 is display information including the display shape and display distance received via the main control device 90, and is displayed on the virtual image display optical system 30 from information obtained based on the signal from the environment monitoring unit 72. A display image IM to be generated is generated. The display image IM is, for example, a display frame HW (FIG. 4B) located in the periphery with respect to the depth position direction and the direction orthogonal thereto with respect to an automobile, bicycle, pedestrian, or other object KT existing behind the display screen 20. For example).

The display control unit 18 receives a detection output related to the presence of the driver UN and the eye position from the driver detection unit 71 via the main control device 90. Thereby, the projection of the display image IM by the virtual image display optical system 30 can be automatically started and stopped. It is also possible to project the display image IM only in the direction of the line of sight of the driver UN. Further, it is possible to perform projection with emphasis such as brightening or blinking only the display image IM in the direction of the line of sight of the driver UN.

The main controller 90 has a role of coordinating the operations of the virtual image display device 100, the environment monitoring unit 72, and the like, and the virtual image display optics so as to correspond to the spatial position of the object KT detected by the environment monitoring unit 72. The spatial arrangement of the display frame HW projected by the system 30 is adjusted.

According to the virtual image display device 100 according to the first embodiment described above, the optical path length changing element 16 having a structure with different thicknesses in the optical axis AX direction is arranged for each of the partial regions 16a to 16d that are predetermined segmented regions. Therefore, the distance from the driver UN to the display image (virtual image) IM can be finely changed depending on the thickness of the optical path length changing element 16, and the display image IM can be superimposed on the real object including the depth direction. Accordingly, even if the viewpoint is shifted, the positional relationship between the display image IM such as a danger signal and the real object does not shift, and thus it is easy to prevent the driver UN from being mistaken.

[Second Embodiment]
The virtual image display device and method according to the second embodiment will be described below. The virtual image display device according to the second embodiment is a modification of the virtual image display device according to the first embodiment, and matters not specifically described are the same as those in the first embodiment.

As shown in FIG. 7, in the case of the virtual image display device 100 of the second embodiment, the optical path length changing element 16 is a rectangular plate-like step-like structure 216.

The arrangement changing device 262, which is a moving unit attached to the optical path length changing element 16 or the stepped structure 216, moves the optical path length changing element 16 to a desired position along the vertical direction perpendicular to the optical axis AX. It is for making it happen. The arrangement changing device 262 includes a guide portion 262a that guides the vertical movement of the step-like structure 216 in the vertical direction perpendicular to the optical axis AX, and the step-like structure 216 in the vertical direction perpendicular to the optical axis AX at a desired speed. And a drive unit 262b for reciprocal movement.

As shown in FIGS. 8A and 8B, the staircase structure 216 has a plurality of partial regions 216a to 216c arranged in a direction perpendicular to the optical axis AX, and the partial regions 216a to 216c are formed in the display region. It has a size and contour shape corresponding to the intermediate image TI. These partial regions 216a to 216c have different thicknesses in the optical axis AX direction. Specifically, the staircase-like structure 216 has a plurality of emission surfaces 216e to 216g arranged in a staircase shape on the virtual image forming optical system 17 side or the rear side of the optical path, and each of the emission surfaces 216e to 216g has It has become a plane. On the other hand, the step-like structure 216 has an incident surface 16j that is a single plane on the imaging optical system 15 side or the optical path upstream side, and the incident surface 16j has a diffusion function. The intermediate image TI is formed in a display region from the step-like structure 216 to the front stage of the optical path. Specifically, the step-like structure 216, that is, the incident surface 16j is within ± 1 mm from the image formation position of the intermediate image TI. Has been placed.

By moving the step-like structure 216 in the direction perpendicular to the optical axis AX by the arrangement changing device 62, the three partial regions 216a to 216c are sequentially moved on the optical axis AX, and the display screen 20 is moved by the virtual image forming optical system 17. It is possible to increase or decrease the distance between the display image IM as a virtual image formed behind the driver UN and the driver UN as an observer. Thus, the display image IM is changed while changing the virtual image distance to the display image IM by changing the position of the projected display image IM forward and backward and by changing the display contents according to the position. As a result, the display image IM as a series of projection images can be made three-dimensional. The moving direction of the staircase structure 216 may be a horizontal direction perpendicular to the optical axis AX, and the number of partial regions is not limited to three.

In the virtual image display device 100 of the second embodiment, the generation distance of the entire virtual image can be changed by sliding the optical path length changing element 16. By sliding the optical path length changing element 16 at a high speed, it can be seen that virtual images are displayed at a plurality of distances simultaneously. Further, the virtual image distance can be finely adjusted by adjusting the number and thickness of the partial regions 216a to 216c constituting the optical path length changing element 16 or the step-like structure 216.

[Third Embodiment]
The virtual image display device and method according to the third embodiment will be described below. The virtual image display device according to the third embodiment is a modification of the virtual image display device according to the first embodiment, and items that are not particularly described are the same as those in the first embodiment.

As shown in FIG. 9, in the case of the virtual image display device 100 of the third embodiment, the optical path length changing element 16 is a rectangular plate-like stepped structure 316, which is fixedly arranged along the optical path.

As shown in FIGS. 10A and 10B, the staircase structure 316 includes a plurality of partial regions 316a to 316c arranged in a direction perpendicular to the optical axis AX, and each partial region 316a to 316c is an intermediate region in the display region. The image TI has a size and contour shape obtained by dividing the image TI into three in the vertical Z direction, and has a size and contour shape corresponding to the intermediate image TI that is the display region as a whole when the partial regions 316a to 316c are combined. These partial regions 316a to 316c have different thicknesses in the optical axis AX direction. Specifically, the staircase structure 316 has a plurality of emission surfaces 316e to 316g arranged in a staircase shape on the virtual image forming optical system 17 side or the optical path rear side, and each of the emission surfaces 316e to 316g It has become a plane. On the other hand, the step-like structure 316 has an incident surface 16j that is a single plane on the imaging optical system 15 side or the optical path upstream side, and the incident surface 16j has a diffusion function. The intermediate image TI is formed on the stepped structure 316 or the display region from the optical path length changing element 16 to the previous stage of the optical path. Specifically, the stepped structure 316, that is, the incident surface 16j, forms an image of the intermediate image TI. It is arranged within ± 1 mm from the position.

In this virtual image display device 100, the intermediate image TI is composed of partial images TIa to TIc divided into three in the vertical Z direction. The partial image TIa is an image for relatively short distance projection, the partial image TIc is an image for relatively long distance projection, and the partial image TIb is an image for medium distance projection. That is, the lower part IMa constituting the display image (virtual image) IM by the virtual image display device 100 is imaged at a relatively short distance corresponding to the partial image TIa, and the upper part IMa constituting the display image (virtual image) IM is formed. The portion IMc is imaged at a relatively long distance corresponding to the partial image TIc. Further, an intermediate portion IMb regarding the upper and lower sides of the display image (virtual image) IM is formed at an intermediate distance corresponding to the partial image TIb. In this case, the positions of the display images IMa to IMc in the depth direction are fixed, but the display image IM is three-dimensional.

In the virtual image display device 100 of the third embodiment, it is not necessary to provide a movable part for the optical path length changing element, so that it is preferable as a device mounted on a vehicle or other moving body. Furthermore, the virtual image distance can be finely adjusted by adjusting the thickness in each partial region. In addition, it is preferable to set the thickness of the partial region so that the long distance display is performed above the virtual image and the short distance display is performed below the virtual image.

When a virtual image is displayed at different positions in the depth direction by the single image forming element 11 as in the virtual image display device 100 of the third embodiment, light is incident across the step boundary of the staircase structure 316, and the virtual image is displayed. Therefore, it is preferable to provide a region that is not used for display as a boundary portion in the image forming element 11 or the intermediate image TI.

[Fourth Embodiment]
The virtual image display device and method according to the fourth embodiment will be described below. Note that the virtual image display device of the fourth embodiment is a modification of the virtual image display device of the first to third embodiments, and items not specifically described are the same as those of the first embodiment.

As shown in FIG. 11, in the virtual image display device 100 according to the fourth embodiment, the main body optical system 13 omits the imaging optical system 15, and the image forming element 11, the optical path length changing element 16, and the virtual image forming optics. It consists of a system 17. For this reason, the display surface 11a of the image forming element 11 serving as a display unit is disposed in the vicinity of the position where the intermediate image TI is present in FIG. The incident surface 16 j disposed on the side of the optical path length changing element 16 facing the image forming element 11 is disposed within 1 cm from the display surface 11 a of the image forming element 11. In this case, the display surface 11a of the image forming element 11 serves as a display area as it is, and the image formed on the display surface 11a is directly enlarged and projected as a display image (virtual image) IM by the virtual image forming optical system 17 or the like. . Note that the incident surface 16j of the optical path length changing element 16 does not have a diffusion function. In the virtual image display device 100 of the fourth embodiment, since the intermediate image TI is not formed in the preceding stage of the optical path of the optical path length changing element 16, the optical path length changing element 16 can be reduced in size.

When the entrance surface 16j of the optical path length changing element 16 is not provided with a diffusion function as in the present embodiment, the thinnest partial region 16c among the partial regions 16a to 16c can be omitted as having a thickness of zero.

The above is an example in which the virtual image display device 100 of the first embodiment is modified. However, the virtual image display devices 100 of the second and third embodiments can be similarly changed, and the main body optical system 13 to the imaging optical system. 15 can be omitted, and the image formed on the display surface 11a as a display area can be directly enlarged and projected as a display image (virtual image) IM without using the intermediate image TI.

[Fifth Embodiment]
The virtual image display device and method according to the fifth embodiment will be described below. The virtual image display device according to the fifth embodiment is a modification of the virtual image display device according to the first to fourth embodiments, and items not specifically described are the same as those in the first embodiment.

As shown in FIG. 12, in the case of the virtual image display device 100 according to the fifth embodiment, the virtual image forming optical system 17 includes only one mirror 517a. Here, the mirror 517a is a first reflector and is a first mirror having optical power. In this case, since the main body optical system (projection optical system) 13 can be simplified, the virtual image display device 100 can be made inexpensive.

[Sixth Embodiment]
The virtual image display device and method according to the sixth embodiment will be described below. The virtual image display device according to the sixth embodiment is a modification of the virtual image display device according to the first embodiment, and matters not specifically described are the same as those in the first embodiment.

As shown in FIG. 13, the main body optical system 13 includes an optical path length changing element 416 disposed between the imaging optical system 15 and the virtual image forming optical system 17.

In the case of the sixth embodiment, the apparent position of the intermediate image TI viewed from the virtual image forming optical system 17 does not change discretely as in the first embodiment, but by the optical path length changing element 416, the virtual image forming optical system. The apparent position of the intermediate image TI viewed from 17 is continuously changed.

The optical path length changing element 416 is arranged immediately after a projection position or an imaging position by the imaging optical system (first projection optical system) 15, and has a rotating body 6a and a hollow frame body 6b, and is an arrangement that is a moving unit. It is driven by the rotation drive device 62a of the changing device 62 and rotates around the rotation axis RX at a constant speed, for example.

14A is a partially broken side view for explaining the optical path length changing element 416, and FIG. 14B is a partially broken front view for explaining the optical path length changing element 416. FIG. The optical path length changing element 416 includes a spiral rotator 6a having a profile close to a disk as a whole, and a cylindrical hollow frame 6b that houses the rotator 6a.

The rotating body 6a has a central portion 6c and an outer peripheral optical portion 6p. The rotating body 6a is a spiral member having light permeability, and the outer peripheral optical part 6p of the rotating body 6a functions as the three-dimensional shape part 106. One surface 6f or the incident surface 16j formed on the outer peripheral optical part 6p of the rotator 6a is a plane perpendicular to the rotation axis RX, but may have a diffusion function. The intermediate image TI is formed in a display region from the optical path length changing element 416 to the preceding stage of the optical path. Specifically, the optical path length changing element 416, that is, the incident surface 16j is within ± 1 mm from the imaging position of the intermediate image TI. Has been placed. The other surface 6s formed on the outer peripheral optical part 6p of the rotating body 6a is a spiral surface having the rotation axis RX as a spiral axis. Since one surface 6s is a flat surface and the other surface 6s is a spiral surface, the rotator 6a has a thickness t that changes in the direction of the rotation axis RX or the optical axis AX. A step portion 6j is formed at one place along the circumference of the optical path length changing element 416. The step portion 6j has a connecting surface 6k that connects the steps between the spiral ends and is inclined with respect to a plane including the rotation axis RX that rotates the optical path length changing element 416.

In the rotating body 6a, one place along the circumferential direction is a functional area FA through which the optical axis AX of the main body optical system 13 passes, and an intermediate image TI is formed in the vicinity of the functional area FA on the image forming element 11 side. Is done. This functional area FA moves at a constant speed on the rotating body 6a as the rotating body 6a rotates. That is, by rotating the rotating body 6a and causing the display light (image light) HK to enter the functional area FA that is a part of the rotating body 6a, the thickness of the functional area FA in the optical axis AX direction is continuously changed instead of stepwise. To do. As a result, the apparent position of the intermediate image TI viewed from the virtual image forming optical system 17 can be continuously changed in the optical axis AX direction. If the display of the image forming element 11 is not operating, an intermediate image as a display is not necessarily formed, but an apparent position where the intermediate image will be formed is also referred to as an apparent position of the intermediate image. In the illustrated example, the apparent position of the intermediate image TI is reciprocated once in the direction of the optical axis AX by one rotation of the rotating body 6a. Hereinafter, the apparent position of the intermediate image TI viewed from the virtual image forming optical system 17 is also referred to as a movable projection position of the intermediate image TI.

The hollow frame 6b has a cylindrical outer contour, and includes a side surface portion 6e and a pair of end surface portions 6g and 6h. The side surface portion 6e and the pair of end surface portions 6g and 6h are formed of the same material having optical transparency. However, the side part 6e does not need to have light transmittance. The rotating body 6a in the hollow frame body 6b is fixed to the hollow frame body 6b via a pair of central shaft portions 65, and the hollow frame body 6b and the rotating body 6a rotate integrally around the rotation axis RX. To do. Thus, by arranging the rotating body 6a provided with the intermediate screen 19 in the hollow frame body 6b, it is possible to suppress dust and the like from adhering to the rotating body 6a, and to generate sound accompanying the rotation of the rotating body 6a. Therefore, it is easy to stabilize the rotation of the rotating body 6a at a high speed.

Returning to FIG. 13, the arrangement of the functional area FA on the rotating body 16a is rotated by rotating the optical path length changing element 416 around the rotation axis RX at a constant speed by the rotation driving device 62a which is a screen driving unit. To do. That is, as shown in FIG. 15A, as the rotating body 6a rotates, the functional area FA on the intermediate screen 19 is sequentially shifted to the adjacent functional area FA ′ set at a position shifted at an equal angle, for example. By such movement of the functional area FA, the optical path length of the optical path passing through the rotating body 6a changes so as to continuously decrease, and the apparent position or intermediate image of the intermediate image TI viewed from the virtual image forming optical system 17 The movable projection position of TI can also be moved to the display surface 11a side of the image forming element 11 along the optical axis AX direction. Although details will be described later, for example, by moving the apparent position of the intermediate image TI viewed from the virtual image forming optical system 17 to the display surface 11a side of the image forming element 11, the projection distance or virtual image distance to the projection image IM can be reduced. Can be increased. Further, by moving the apparent position of the intermediate image TI viewed from the virtual image forming optical system 17 to the virtual image forming optical system 17 side, the projection distance or the virtual image distance to the projection image IM can be reduced.

The virtual image forming optical system (second projection optical system) 17 enlarges the intermediate image TI formed by the imaging optical system (first projection optical system) 15 through the optical path length changing element 416, and the driver VD as an observer. A projection image IM as a virtual image is formed in front of. The virtual image forming optical system 17 can have an optical characteristic that compensates for distortion of image formation and light beam deflection caused by the optical path length changing element 416 and the like.

In the image display apparatus 100 shown in FIG. 13 and the like, the optical path length changing element 416 rotates around the rotation axis RX and corresponds to the functional area FA by operating the rotation driving device 62a under the control of the display control unit 18. The apparent position of the intermediate image TI or the movable projection position of the intermediate image TI repeatedly and periodically moves in the direction of the optical axis AX, and the projected image IM as a virtual image formed behind the display screen 20 by the virtual image forming optical system 17. And the driver VD as the observer can be made larger or smaller. As described above, the position of the projected image IM to be projected is changed back and forth, and the image forming element 11 is synchronized with the apparent arrangement of the intermediate image TI under the control of the display control unit 18. By making the display content of the display element 11 according to the position, the display content of the projection image IM is changed while changing the projection distance or virtual image distance to the projection image IM, and a series of projection images The projected image IM can be made three-dimensional.

The rotational speed of the optical path length changing element 416 or the rotating body 6a or the moving speed of the functional area FA can be seen as if the projected image IM as a virtual image is simultaneously displayed at a plurality of locations or a plurality of projection distances in the depth direction. It is desirable to be speed. Here, if the projection image IM of each distance zone (sub zone described later) is switched at 30 fps or more, preferably 60 fps or more, a plurality of displayed images are visually recognized as continuous images. For example, assuming that the projection image IM is sequentially projected in five steps from a short distance to a long distance in accordance with the operation of the optical path length changing element 416, when the image forming element 11 performs display at 200 fps, each distance (for example, The display of the short-distance projection image IM is switched at 40 fps, and the projection image IM at each distance is performed in parallel and the switching is recognized as being substantially continuous.

FIG. 15B is a diagram specifically illustrating a change in the apparent position of the intermediate image TI as viewed from the virtual image forming optical system 17 or the movable projection position of the intermediate image TI as the optical path length changing element 416 rotates. As the optical path length changing element 416 rotates, the movable projection position of the intermediate image TI is a sawtooth shaped temporal pattern PA along the optical axis AX direction when the image forming element (display element) 11 performs continuous display. Repeatedly move periodically. That is, the position of the intermediate image TI changes continuously and periodically with the rotation of the optical path length changing element 416, while being discontinuous at the position corresponding to the step portion 6j. As a result, although not shown, the position of the projected image (virtual image) IM is also different in scale, but repeatedly moves periodically along the optical axis AX in the same manner as the movable projected position of the intermediate image TI, and the projection distance Can be changed continuously. Here, since the image forming element 11 does not perform continuous display but performs intermittent display while switching display contents, the movable projection position of the intermediate image TI is also discrete on the sawtooth-shaped temporal pattern. Position. In the temporal pattern PA, the display position Pn closest to the near distance side or the virtual image forming optical system 17 and the display position Pf closest to the far distance side or the anti-virtual image forming optical system 17 ensure a margin, and the temporal pattern PA It is set at a position away from the both ends by a predetermined amount. Further, the break PD in the temporal pattern PA corresponds to the step portion 6j provided in the rotating body 6a of the optical path length changing element 416.

Here, when displaying an image in a certain distance zone, the displayed distance in the depth direction changes by changing the position of the apparent intermediate image within the displayed time as shown in FIG. 15B. To do. At this time, the display distance that can be seen by the observer (driver) in the display zone in which the distance in the depth direction changes is approximately the average position of the distance in the depth direction that changes within the display time.

FIG. 16 is a diagram for explaining the relationship between the movable projection position of the intermediate image and the projection distance or the relationship between the movable projection position of the intermediate image and the display zone. When the virtual image of the intermediate image TI viewed from the virtual image forming optical system 17 is moved at the same speed in the direction of the optical axis AX according to the characteristic C1 indicated by the one-dot chain line, the switching time interval δ of each distance zone is set to a constant value. For example, the step size of the projection distance is short at a short distance and long at a long distance. The apparent step size Δ of the movement of the intermediate image or the virtual image of the intermediate image TI is equal to the switching time of the distance zone to be displayed.

When the time for moving between both ends of the movable projection position of the intermediate image shown in FIG. 15B is considered as one cycle, the display unit having the depth is set as a display zone, and the time of the one cycle is the display time of each display zone, If the time is shorter than the product of the number n of display zones, the display zone extends over a plurality of distance zones, and at least adjacent display zones overlap in the projection distance range displayed in each zone (FIG. 16). Display zones DZ1 to DZn). By performing overlapping display in this way, the same projected image (virtual image) can be displayed with a spread in the depth direction, and the display time of each display zone is made longer compared to a display that does not overlap. And the brightness of the projection image (virtual image) IM is improved.

As illustrated in FIG. 16, n display zones can be set along the characteristic C1. Here, for convenience of explanation, the shortest display zone is called a first display zone DZ1, and the farthest display zone is called an nth display zone DZn (n is a natural number). In the plurality of display zones DZ1 to DZn, the distance width of display increases as the distance increases from the short distance. Among the plurality of display zones DZ1 to DZn, adjacent display zones partially overlap in projection distance. That is, the projection distances of the kth display zone DZk (k is a natural number smaller than n) and the (k + 1) th display zone DZk + 1 partially overlap. For example, the second display zone DZ2 and the third display zone DZ3 are projected distances. Are partially overlapping. The k-th display zone DZk also displays an image displayed in the display zone set before, after, or before and after the original display image of the projection distance of the display target to be displayed there. It is a composite projection image. In the example shown in the figure, the entire zone or the corresponding zones corresponding to the sub-zones LZk-2 to LZk + 1 are displayed in a certain period of time while the k-th display zone is being displayed. ing. In this case, the display time of the image displayed in each of the display zones DZ1 to DZn is shifted between the adjacent display zones DZ1 to DZn at the pitch δ of the display time. The distance between both ends of the near side and the far side varies, and the average distance also varies. Since the human eye or the brain captures the display image at the average distance of the display zones DZ1 to DZn, even when displaying simultaneously, the display distances of the respective display zones DZ1 to DZn are displayed as different positions. Can be in a state.

In addition, when the kth display zone DZk is divided at the timing when the overlapping distance zones are switched and considered as a series of subzones LZk-2 to LZk + 1 including the reference subzone LZk, a display operation is appropriately performed on the image forming element (display element) 11. By doing so, the same projected image (virtual image) IM is displayed in each subzone. That is, the display zone DZk is configured by a combination of a series of a plurality of subzones LZk−2 to LZk + 1 whose distance changes stepwise. At this time, in consideration of the change in the projection distance, the same projection image (virtual image) IM is displayed in an overlapping manner in the adjacent distance zones LZk−2 to LZk + 1 so that the positions and the angle sizes coincide with each other. Thereby, the projection image (virtual image) IM in which the projection distance changes can be displayed in a state where there is no deviation or blurring. In addition, the average display distance at this time is a distance corresponding to the reference subzone LZk. In FIG. 16, for convenience of display, the display zones DZ1 to DZn are shown to extend in the horizontal direction. However, when the vertical axis is the position of the intermediate image, the display zones DZ1 to DZn have characteristics C1. It will extend along.

The display times in the first display zone DZ1 to the nth display zone DZn are all equal. By equalizing the display time in each of the display zones DZ1 to DZn, the display brightness of each of the display zones DZ1 to DZn can be matched, and the driver VD who is an observer unintentionally focuses on an image at a specific distance. Can be prevented from occurring. Depending on the application, it is possible to provide a difference in display luminance in each of the display zones DZ1 to DZn. For example, for a display zone corresponding to long-distance projection, it is possible to increase the display brightness.

When displaying different objects in a specific depth direction on the screen, display objects with different distances are close to each other in a two-dimensional plane other than the depth direction, or overlap each other, and there is interference between the displays. It is thought that it will occur, and it is necessary to avoid this. For example, when a display target existing at a different display distance DZk ′ with respect to a display target in the display zone DZk is located in the vicinity in the two-dimensional plane and interference occurs in the display for each target, these are displayed in the interference region. It is conceivable to display such that Specifically, in a common area or intersection area where a pair of display objects overlap, a pair of display objects are images that are displayed in a semi-transparent superimposed manner, and in a difference area or an independent area where a pair of display objects do not overlap, The standard display is sufficient. Alternatively, it is possible to make a display that makes a difference by using methods such as color and size (including thickness in the case of lines), brightness, and blinking, and use various display methods that are devised to communicate to the driver. Can do.

FIG. 17 is a conceptual diagram illustrating the operation of the main control unit 90 in the sixth embodiment. First, when the main control unit 90 detects an object using the environment monitoring unit 72, the main control unit 90 generates display data corresponding to the display frame HW surrounding the target object KT (see FIG. 4A and the like) corresponding to the object. It is stored in the illustrated storage unit (step S11). Thereafter, the main control unit 90 performs data conversion such that the display data obtained in step S11 is distributed to the corresponding display zones DZ1 to DZn (step S12). Specifically, according to the position of one or more objects KT, one or more corresponding display frames HW are displayed in any one of the display zones DZ1 to DZn (in the example of FIG. 11, display zones DZa to DZc). Assign to. Next, the main control unit 90 processes the display data corresponding to one or more display frames HW so as to match the assigned display zones DZ1 to DZn, and stores them in a storage unit (not shown) (step S13). This adaptation includes image processing such as correcting the outline and arrangement of the frame image for each of the distance zones LZk−2 to LZk + 1. Thereafter, the main control unit 90 synthesizes the display data adapted in step S13 with the existing data (step S14). Although the display by the display zones DZ1 to DZn is performed in parallel at the same time, although there is a time difference, the display is performed so as to leave an afterimage for a short time, so when a new target KT appears, the existing target In view of this, it is necessary to reorganize the display contents so that the new object and the new object coexist. Finally, the main control unit 90 outputs the display data obtained in step S15 to the display control unit 18 in synchronization with the operation of the rotation driving device 62a, and the image forming element (display element) 11 has the function of the rotating body 6a. A display operation corresponding to the movable projection position of the area FA or the intermediate image TI is performed.

FIG. 18 is a diagram for explaining the operation of the image forming element 11. In this case, the first to nth display areas arranged in the vertical direction correspond to the first to nth display zones DZ1 to DZn shown in FIG. In one cycle corresponding to one rotation of the rotator 6a, the first display area to the nth display on the display surface 11a of the image forming element (display element) 11 corresponding to the first to nth display zones DZ1 to DZn. The display in the area is repeated. In each display area, the signals F1 to F4 mean that the same display image is repeated in four subzones, and each of the signals F1 to F4 includes R, G, and B signal components for color display. ing.

In the above sixth embodiment, the spiral shape as a three-dimensional shape formed on the rotating body 6a is not limited to one cycle, and the azimuth region can be divided into a plurality of cycles. Further, the spiral shape of the rotating body 6a is not limited to linearly increasing / decreasing the thickness, but may be one that increases / decreases the thickness nonlinearly.

According to the virtual image display apparatus or method of the present embodiment, the movable projection position of the intermediate image is continuously changed by rotating the optical path length changing element 416 around the rotation axis RX, and the simple configuration is reliable. It is possible to display while changing the display position of the virtual image at a high speed including the depth direction while securing the property.

Further, according to the virtual image display apparatus or method of the present embodiment, since the image forming element (display element) 11 performs display in synchronization with the rotation of the optical path length changing element 416 that changes the projection distance, the depth direction is included. Thus, virtual images with different display positions can be displayed while changing at high speed, and various images can be simultaneously projected at a plurality of distance positions. At this time, the control units 90 and 18 set the projection distance so as to partially overlap in adjacent display zones among the plurality of display zones DZ1 to DZn that change the projection distance. When displaying in the display zone with the number of distance divisions set within one period, changing from the far end to the far end or displaying from the far end to the near end, the projection distance of the adjacent display zone Compared to a display without overlapping, by providing overlapping even with the same number of divisions, it is possible to lengthen the projection time or display time by each display zone, and it becomes easy to simultaneously project a high-luminance image.

[Seventh Embodiment]
The virtual image display device and method according to the seventh embodiment will be described below. The virtual image display device according to the seventh embodiment is a modification of the virtual image display device according to the second embodiment or the sixth embodiment, and matters not specifically described are the same as those in the second or sixth embodiment.

As shown in FIG. 19, the main body optical system 13 includes an optical path length changing element 516 disposed between the imaging optical system 15 and the virtual image forming optical system 17. The optical path length changing element 516 is a three-dimensionally shaped portion formed in a wedge shape, and is thin on the tip side and thick on the root side.

By moving the optical path length changing element 516 in the direction perpendicular to the optical axis AX by the arrangement changing device 62, the location where the optical axis AX crosses in the optical path length changing element 516 sequentially moves, and the intermediate position viewed from the virtual image forming optical system 17 The apparent position of the image TI or the movable projection position of the intermediate image TI moves. As a result, the distance between the display image IM as a virtual image formed behind the display screen 20 by the virtual image forming optical system 17 and the driver UN as an observer can be increased or decreased.

Also in the virtual image display device of the seventh embodiment, the apparent position of the intermediate image TI viewed from the virtual image forming optical system 17 is continuously changed as in the sixth embodiment. Therefore, display control similar to that in the sixth embodiment is performed. I do. At this time, the movable projection position of the intermediate image TI can be moved at a constant speed as shown in FIG. 15B, but can also be moved at a periodically changing speed such as a sine wave. In this case, if the display zones DZ1 to DZn are set in consideration of the moving speed of the optical path length changing element 516, the luminance of the display frame HW and the like can be made uniform regardless of the projection position.

In addition, when color dispersion becomes remarkable by the optical path length changing element 516, the image forming element 11 can perform display with a color shift in advance.

[Eighth Embodiment]
The virtual image display device according to the eighth embodiment will be described below. The virtual image display device according to the eighth embodiment is a modification of the virtual image display device according to the first to seventh embodiments, and items not specifically described are the same as those in the first embodiment.

As shown in FIG. 20, in the case of the virtual image display device 100 according to the eighth embodiment, a display screen 220 is pasted inside a rectangular reflection region 8d provided in front of the driver's seat of the windshield 8 forming the front window. ing. That is, a half mirror is formed on the windshield 8. The display screen 220 can also be embedded in the windshield 8.

Although the virtual image display device 100 as a specific embodiment has been described above, the virtual image display device according to the present invention is not limited to the above. For example, the optical path length changing element 16 in the first to fifth embodiments is not limited to the staircase structure, and may include divided regions or partial regions 16a to 16d separated from each other. In this case, the divided area or the partial area can be connected to each other by a connecting member such as a frame.

When each of the partial regions 16a to 16d constituting the optical path length changing element 16 has a different thickness, it is desirable to incorporate a balancer for smooth rotation. However, if the number of partial regions constituting the optical path length changing element 16 is twice as many as the virtual image display distance, the rotational balance of the optical path length changing element 16 is arranged by arranging the partial areas corresponding to the same virtual image display distance to face each other. Can be increased.

In the first embodiment, the arrangement of the virtual image display device 100 can be turned upside down, and the display screen 20 can be arranged at the upper part of the windshield 8 or at the sun visor position. A screen 20 is arranged. Further, the display screen 20 may be disposed at a position corresponding to a conventional mirror of an automobile.

In the above-described embodiment, the outline of the display screen 20 is not limited to a rectangle, but may be various shapes.

The image forming optical system 15 and the virtual image forming optical system 17 shown in FIG. 2 and the like are merely examples, and the optical configurations of the image forming optical system 15 and the virtual image forming optical system 17 can be changed as appropriate. For example, an intermediate image as a preceding stage of the intermediate image TI can be additionally formed in the imaging optical system 15. One or more mirrors having no optical power may be disposed in the optical path of the imaging optical system 15 and the virtual image forming optical system 17. In this case, it may be advantageous for downsizing the drawing unit 10 and the like by folding.

In the above embodiment, the display screen (combiner) 20 is a flat plate, but the display screen 20 can be a free curved surface or other curved surface while taking into consideration the optical specifications of the main body optical system 13.

In the first to fifth embodiments, the display position of the display image (virtual image) IM is not limited to the three or four illustrated in the above embodiment, and can be set to an appropriate number of five or more. The display of the display image IM can be performed continuously or intermittently by changing the position.

In the first to fifth embodiments, the diffusion regions 16a to 16d of the optical path length changing element 16 are illustrated as rectangles. However, the diffusion region of the optical path length changing element 16 may be trapezoidal, fan-shaped, or other shapes. In a more preferred embodiment, the shape is in consideration of the number of regions of the diffusion screen, the relationship between the rotation axis RX and the optical axis AX, the rotation speed, and the like.

The virtual image display device 100 described above is not limited to a projection device mounted on an automobile or other moving body, but can be incorporated in a digital signage or the like, but can also be applied to other uses.

Claims (17)

1. A display unit, and a virtual image display optical system for enlarging an image formed in a display region by the display unit,
   A virtual image display device in which optical path length changing elements having structures having different thicknesses in the optical axis direction are arranged in an optical path from the display region to the first reflector.
2. The virtual image display device according to claim 1, wherein the optical path length changing element has a predetermined segmented region having a thickness different in an optical axis direction.
3. The optical path length changing element is a stepped structure including a plurality of partial regions each having a size corresponding to a display region of the display unit and having different thicknesses in the optical axis direction as the predetermined segmented region. The virtual image display device described in 1.
4. 4. The virtual image display device according to claim 3, wherein the optical path length changing element is a disk-like structure provided around the center with the plurality of partial regions having different thicknesses in the optical axis direction.
5. The optical path length changing element is a stepped structure having a size corresponding to a display area of the display section as a whole and including a plurality of partial areas having different thicknesses in an optical axis direction as the predetermined segmented area. Item 3. The virtual image display device according to Item 2.
6. The virtual image display device according to any one of claims 1 to 5, wherein the optical path length changing element has a plane of incidence and emission.
7. The virtual image display device according to claim 6, wherein the optical path length changing element has a stepped shape in which the exit surface disposed on the opposite side of the display region includes a plurality of planes.
8. The display unit forms an intermediate image corresponding to the display surface of the image forming element on the display region from the optical path length changing element to the front stage of the optical path,
   The virtual image display device according to any one of claims 1 to 7, wherein the optical path length changing element is disposed within ± 1 mm from an imaging position of an intermediate image, and an incident surface on the display region side has a diffusion function. .
9. The display unit is an image forming element,
   The incident surface arranged on the side of the optical path length changing element facing the image forming element is arranged within 1 cm from the display surface of the display element. Virtual image display device.
10. The virtual image display device according to claim 1, wherein the optical path length changing element has a three-dimensional shape in which the thickness of the functional region in the optical axis direction changes continuously by rotation.
11. The display unit performs display in synchronization with the movement of the optical path length changing element that changes the projection distance, and the projection distances partially overlap in adjacent display zones among the plurality of display zones that change the projection distance. The virtual image display device according to claim 10, further comprising a control unit configured to make the setting as described above.
12. The virtual image display device according to any one of claims 1 to 11, further comprising a moving unit that moves the optical path length changing element.
13. The virtual image display optical system includes a first mirror corresponding to the first reflector and having an optical power, and a half mirror having an optical power that is disposed in the latter stage of the optical path of the first mirror. The virtual image display device according to any one of claims 1 to 12, further comprising:
14. The virtual image display optical system includes a first mirror corresponding to the first reflector and having an optical power, and a second mirror having an optical power that is disposed downstream of the optical path of the first mirror. The virtual image display device according to any one of claims 1 to 12, further comprising: a half mirror that is disposed downstream of the optical path of the second mirror and has optical power.
15. The virtual image display device according to any one of claims 13 and 14, wherein the half mirror is a combiner.
16. The virtual image display device according to any one of claims 13 and 14, wherein the half mirror is a windshield.
17. A virtual image display method using a display unit and a virtual image display optical system for enlarging an image formed in a display region by the display unit,
    A virtual image display method in which optical path length changing elements having structures having different thicknesses in the optical axis direction are arranged in an optical path from the display region to the first reflector, and the projection distance is changed by the arrangement of the optical path length changing elements.

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