JP2020166072A - Head-up display device - Google Patents

Abstract

To secure a wide vision to see a display image while reducing rotation and/or movement of an optical member.SOLUTION: The head-up display device is provided with a display unit 10 that generates light of a display image, and a holographic optical system 20 that diffracts light, which results from the incidence of the light of the display image, to a plurality of different directions, delivers first diffraction light 101 to a first region 201 where a first virtual image of the display image can be seen, and delivers second diffraction light 102 to a second region 202 where a second virtual image of the display image can be seen and that is disposed above the first region 201.SELECTED DRAWING: Figure 3

Description

The present disclosure relates to a head-up display device used for a moving body such as a vehicle.

In Patent Document 1, the position (height) of the eyes is described by changing the position where the light of the display image is projected by rotating and / or moving the mirror that reflects the light of the display image by an actuator or the like. Disclosed is a head-up display device capable of allowing different observers to visually recognize a virtual image of a displayed image.

International Publication No. 2017/138242

An actuator for rotating or moving an optical member (for example, a mirror of Patent Document 1) has been required. Further, it is necessary to provide a large space for rotating and / or moving the optical member for directing the light of the displayed image to observers having different eye positions, and it is necessary to reduce the number of actuators or rotate the optical member. And / or there was room for improvement in terms of reducing movement.

A summary of the particular embodiments disclosed herein is presented below. It should be understood that these aspects are presented solely to provide the reader with an overview of these particular embodiments and do not limit the scope of this disclosure. In fact, the present disclosure may include various aspects not described below.

The outline of the present disclosure ensures a wide viewing range in which the displayed image can be visually recognized while reducing the rotation and / or movement of the optical member. More specifically, it relates to reducing the number of actuators that rotate and / or move the optical member.

Therefore, the head-up display device described in the present specification incidents the light of the display image with the display (10) that generates the light of the display image, and directs the light of the display image in a plurality of different directions. The first virtual image of the displayed image can be visually recognized by distributing the first diffracted light (101) to the first region (201) where the first virtual image of the displayed image can be visually recognized. A holographic optical system (20) that distributes the second diffracted light (102) to the second region (202) arranged above the first region (201) is provided. According to this, by using a holographic optical system that receives image light from a display, generates a plurality of diffracted lights in different directions of reflection (diffracting), and projects them onto a projected portion, the height of the eyes The image can be visually recognized by different observers. In the past, for observers with different eye heights, the direction of the display light was changed by moving and / or rotating the optical system in the HUD device with an actuator or the like. It is also possible to abolish the actuator that drives the optical system, and even if an actuator is provided, the movable range can be kept small.

It is a figure which shows the schematic structure of the head-up display device which concerns on some embodiments. It is a figure which shows the structure of the display which concerns on some embodiments. It is a figure which showed the optical path of the 1st diffracted light and the 2nd diffracted light of the head-up display device which concerns on some Embodiments. It is a figure explaining an example of the structure of the holographic optical system which concerns on some Embodiments, the incident light from the display which is incident | region | light | light path of the 1st diffracted light and the 2nd diffracted light of this incident light. .. Modifications of the configuration of the holographic optical system according to some embodiments, incident light from a display incident on the holographic optical system, first diffracted light of this incident light, optical path of second diffracted light, and surface reflected light. It is a figure explaining. It is a figure explaining the modification of the structure of the holographic optical system which concerns on some embodiments.

Hereinafter, embodiments according to the present invention will be described with reference to the drawings. The present invention is not limited to the following embodiments (including the contents of the drawings). Of course, changes (including deletion of components) can be made to the following embodiments. Further, in the following description, in order to facilitate understanding of the present invention, description of known technical matters will be omitted as appropriate.

Hereinafter, FIGS. 1 and 3 provide an exemplary configuration of the HUD device and an explanation of the optical path of the display light emitted from the HUD device. FIG. 2 provides a description of an exemplary display configuration. In FIGS. 4, 5, and 6, an example of the configuration of the holographic optical system will be described.

FIG. 1 is a diagram showing a part of a head-up display device according to an embodiment of the present invention, and shows a case where it is adopted in an automobile. The head-up display device of the present invention (hereinafter, also referred to as a HUD device) can be used not only for automobiles but also for display devices in mobile objects.

The HUD device 1 of FIG. 1 is the front of the own vehicle arranged in front of the observer (typically, the driver seated in the driver's seat of the own vehicle) 2 (forward, which can be said to be the traveling direction of the own vehicle). The display light 100 is projected toward the windshield (an example of the projected member) 3. The display light 100 emitted by the HUD device 1 is reflected by the front windshield 3 of the own vehicle toward the observer 2, and is distributed to the eye box 200, which is a predetermined area. By arranging the eyes in the eye box 200, the observer 2 can visually recognize the virtual image 300 of the display image displayed by the HUD device 1 on the side farther from the front windshield 3. In the drawings used in this embodiment, the left-right direction of the own vehicle is the X-axis direction (the left side when facing the front of the own vehicle is the X-axis positive direction), and the vertical direction is the Y-axis direction (self traveling on the road surface). The upper side of the vehicle is the Y-axis positive direction), and the front-rear direction of the own vehicle is the Z-axis direction (the front of the own vehicle is the Z-axis positive direction).

The "eye box" used in the description of the present embodiment means an area where at least a part of the displayed image can be visually recognized in the (1) area and a part of the displayed image is not visible outside the area, or (2) displayed in the area. At least a part of the image is visible at a predetermined brightness or higher, and outside the region, the entire displayed image is a region having a brightness lower than the predetermined brightness. That is, when the observer 2 arranges the eyes (both eyes) outside the eye box 200, the observer 2 cannot see the entire display image, or the visibility of the entire display image is very low and difficult to perceive. The predetermined brightness is, for example, about 1/50 of the brightness of the display image at the center of the eye box.

The HUD device 1 includes a display 10 that emits light from a display image and a holographic optical system 20 that reflects the display light 100 emitted by the display 10 toward a front windshield (an example of a projected member) 3. Consists of at least. That is, in addition to these, the HUD device 1 may add a refractive optical system such as a lens, a catadioptric system such as a plane mirror or a concave mirror, a diffraction optical system, and / or an optical system combining these functions.

The display 10 is, for example, a laser scanning display device, which includes a light source unit 11, a scanner 12 including a MEMS (Micro Electro Mechanical System) mirror, and a screen 13, and displays a display image on the screen 13 ( It emits light from the displayed image.) The displayed image may be distorted in advance and displayed on the screen 13 so as to cancel the distortion (curvature) caused by the holographic optical system 20 and the projected member (front windshield 3). The distortion of the display image may be caused by the warping process by the control unit (not shown) of the display device 10 and the arrangement of each configuration of the optical member in the laser scanning display device.

The light source unit 11 emits a composite light beam 15 in which light beams of a plurality of different colors such as red, green, and blue are combined. The light source unit 11 is located on the optical path of, for example, a semiconductor laser light source (not shown) that emits a monochromatic light beam and a monochromatic light beam emitted from the semiconductor laser light source, and is not shown for condensing the monochromatic light beam. It is composed of a condensing lens and a photosynthesis unit (not shown) including a dichroic mirror that aligns the traveling directions of monochromatic light beams. It should be noted that the folded mirror 11a which is arranged on the optical path of the synthetic light beam 15 emitted from the light source unit 11 and reflects the synthetic light beam 15 toward the scanner 12 may be provided. The folded mirror 11a may be omitted. Further, the folded mirror 11a may be formed in a curved surface shape, and the received synthetic light beam 15 may be optically adjusted and then reflected by the scanner 12.

The scanner 12 is composed of, for example, a piezoelectric-driven biaxial laser light scanning mirror. In the scanner 12, the reflecting surface swings in the biaxial direction in response to a control signal input from the control unit of the display 10. Specifically, the scanner 12 receives the synthetic light beam 15 and directs the scanning beam 17, which is the reflected light reflected from the synthetic light beam 15, to the screen 13.

The screen 13 functions as an exit pupil magnifying element (EPE) that receives the incident scanning beam 17 and magnifies the exit pupil. For example, the screen 13 is a microlens array in which a plurality of microlenses are arranged. In the present embodiment, the screen 13 has a flat plate shape, but a part or the whole may be curved. Further, a field lens (not shown) may be arranged in the vicinity of the screen 13 on the optical path of the scanning beam 17 between the scanner 12 and the screen 13.

As another example, the display 10 may be composed of a liquid crystal projector, a DLP projector, an LCOS projector, and a screen that receives the projected light of these projectors and displays a display image. Further, the projector including the laser scanning display device may not have a screen and may project the display image onto the holographic optical system 20 described later. Further, the display 10 may be an LCD panel or an organic EL display panel that transmits light from a backlight such as an LED.

The holographic optical system 20 is arranged on the optical path of the display light 100 between the display 10 and the external projected member (front windshield 3) of the HUD device 1, and the display light 100 from the display 10 Has a reflectivity that reflects toward the front windshield 3. Further, the holographic optical system 20 of the present embodiment has an image enlargement function (an example of an optical function) for forming an image of the display image generated by the display 10 as an enlarged virtual image 300, and has no distortion (less distortion). ) It may have an image distortion correction function (an example of an optical function) for forming an image as a virtual image 300. By providing the holographic optical system 20 with a concave mirror function (image enlargement function and / or image distortion correction function), it is possible to provide the observer 2 with a large display image (virtual image) and a display image with little distortion. At the same time, it is possible to reduce the size of the display 10 and other optical systems (which may also include the holographic optical system 20) in the HUD device 1, and further to reduce the size of the entire HUD device 1. ..

FIG. 3 is a diagram showing an optical path of the display light 100 (first diffracted light 101, second diffracted light 102) of the HUD device 1 according to the present embodiment. The holographic optical system 20 of FIG. 3 receives the light of the display image (hereinafter, also referred to as incident light 10L) from the display 10 and diffracts the first diffracted light 101 in two different directions. The display light 100 including the second diffracted light 102 and the second diffracted light 102 is projected onto the front windshield 3. The holographic optical system 20 sets the diffraction direction of the first diffracted light 101 so that the first diffracted light 101 reflected by the front windshield 3 is distributed to a predetermined region (first eyebox 201). However, the second diffracted light 102 reflected by the front windshield 3 is distributed to the region (second eyebox 202) above the first eyebox 201 (in the positive direction of the Y axis). 2 The diffraction direction of the diffracted light 102 is set. The observer 2 who has his eyes placed in the first eye box 201 visually recognizes the first virtual image 301 of the displayed image and does not visually recognize the second virtual image 302 of the displayed image (the brightness is so low that it is difficult to see). The virtual image 302 of 2 is visually recognized.) On the other hand, the observer 2 who placed his eyes on the second eye box 202 visually recognizes the second virtual image 302 and does not visually recognize the first virtual image 301 (the first virtual image 301 whose brightness is so low that it is difficult to see is visually recognized. To do.). These are set by utilizing the angle selectivity (an example of the optical function) of the holographic optical system.

FIG. 4 shows an example of the configuration of the holographic optical system 20 according to the present embodiment, the incident light 10L from the display 10 incident on the holographic optical system 20, the first diffracted light 101 and the second diffracted light 102 of the incident light 10L. It is a figure explaining an optical path. The holographic optical system 20 of FIG. 4 is composed of, for example, a hard base material 21 such as glass and a holographic layer 22 provided on the base material 21. The holographic layer 22 of FIG. 4 is formed by laminating the first hologram 23 and the second hologram 24 in this order from the base material 21 side. The first hologram 23 and the second hologram 24 are optical members made of, for example, a hologram material such as a photopolymer or gelatin dichromate and having angle selectivity to reflect incident light in a desired direction. , Created by recording the interference pattern of object light and reference light. In the laminating method, the material of the first hologram 23 is first applied on the base material 21, the desired optical function is recorded and fixed, and then the material of the second hologram 24 is applied on the first hologram 23. , The desired optical function may be recorded. Further, the first hologram 23 and the second hologram 24 on which the optical functions are recorded in advance may be formed by laminating them on the base material 21 in order. Further, the holographic layer 22 may be a single holographic optical system in which diffraction directions in a plurality of directions are recorded. In other words, the holographic layer 22 does not have to be a stack of a plurality of holograms.

The diffraction rate (transmittance, reflectance) of the first hologram 23 and the second hologram 24 can be changed by changing the hologram material and / or changing the thickness and the refractive index modulation of the hologram material. The hologram of the layer on the front surface side of the holographic layer 22 (second hologram 24 in FIG. 4) has higher transmittance than the hologram of the layer on the back surface side of the holographic layer 22 (first hologram 23 in FIG. 4). Is set to be. Ideally, the second hologram 24 is a partially reflective hologram having a transmittance of 50% (reflectance 50%), and the first hologram 23 is a total reflection having a transmittance of 0% (reflectance 100%). It is preferably a type hologram (reflection type hologram). Further, each of the first hologram 23 and the second hologram 24 may have an image enlargement function and / or an image distortion correction function by recording the function of the concave mirror.

Subsequently, an example of setting the diffraction direction using the angle selectivity of the holographic optical system will be described with reference to FIG. Here, the angle of incidence of the incident light 10 L from the display 10 on the holographic optical system 20 (the second hologram 24 on the most surface side) is set to θi2, and the reflection of the second diffracted light 102 diffracted by the second hologram 24. The angle (diffraction angle) is θr2, the angle of incidence of the incident light 10L transmitted through the second hologram 24 on the first hologram 23 is θi1, and the reflection angle (times) of the first diffracted light 101 diffracted by the first hologram 23. (Diffraction angle) is θr1. Since the incident light 10L incident on the first hologram 23 is refracted by the first hologram 23, the incident angle θi1 on the first hologram 23 and the incident angle θi2 on the second hologram 24 are typically different. In FIG. 4, they are shown as equal. In FIG. 4, the first hologram 23 and the second hologram 24 have an angle selectivity that increases the reflection angle with respect to the incident angle. That is, the reflection angle θr1 of the first diffracted light 101 diffracted by the first hologram 23 with respect to the holographic optical system 20 (first hologram 23) is larger than the incident angle θi1, while the second diffracted by the second hologram 24. The reflection angle θr2 of the diffracted light 102 with respect to the holographic optical system 20 (second hologram 24) is larger than the incident angle θi2 and smaller than the reflection angle θr1 of the first diffracted light 101 (θr1 <θr2). The angle selectivity of the hologram 23 and the second hologram 24 is set. As a result, the first diffracted light 101 and the second diffracted light 102 are diffracted in different directions, and in the first diffracted light 101, the observer 2 having a relatively low eye height visually recognizes the first virtual image 301. The light is distributed to the possible first eye box 201, and the second diffracted light 102 is distributed to the second eye box 202 where the observer 2 having a relatively high eye height can see the second virtual image 302. ..

In the present embodiment, the diffraction angle is set so that the reflection angle of both the first diffracted light 101 and the second diffracted light 102 diffracted by the holographic optical system 20 is larger than the incident angle. This makes it possible to direct the diffracted light in a direction far away from the incident light 10L. As a comparative example, by increasing the incident angle of the incident light 10L from the display 10 and thereby increasing the reflection angle, it is possible to prevent the diffracted light from the holographic optical system 20 from hitting the display 10. However, in this case, the incident angle of the incident light 10L from the display 10 with respect to the holographic optical system 20 becomes large. On the other hand, in the holographic optical system 20 of the present embodiment, since the diffraction angle is set so that the reflection angle of each of the diffracted diffracted light is larger than the incident angle, the incident light from the display 10 is set. It is possible to prevent the diffracted light from hitting the display 10 while keeping the angle of incidence on the 10 L holographic optical system 20 small. By keeping the angle of incidence of the incident light 10L from the display 10 on the holographic optical system 20 small, the optical functions (image enlargement function, image distortion correction function, angle selection function) given to the holographic optical system 20 are enhanced. It can be executed while suppressing stray light, or it can be executed while suppressing an increase in design difficulty.

The diffraction rate (the ratio of the light intensity explained to the intensity of the incident light) of the plurality of stacked holograms (first hologram 23, second hologram 24) in the holographic optical system 20 is such that each diffracted light distributes light. The brightness of each virtual image (first virtual image 301, second virtual image 302) visually recognized in the region (first eye box 201, second eye box 202) may be set to be equal. preferable. Specifically, the diffraction coefficient of the hologram close to the front surface side of the holographic layer 22 (the second hologram 24 in the above embodiment) is set to the diffraction coefficient of the hologram close to the back side of the holographic layer 22 (the first hologram 23 in the above embodiment). ) Is preferably set lower than the diffraction coefficient.

Further, the magnification of the display image in the plurality of stacked holograms (first hologram 23, second hologram 24) in the holographic optical system 20 is the region (first eye box 201) in which the diffracted light is distributed. , It is preferable that the sizes of the respective virtual images (first virtual image 301 and second virtual image 302) visually recognized by the second eye box 202) are set to be the same.

As described above, in the present embodiment, the holographic optics that receives the image light from the display, generates a plurality of diffracted lights having different reflected (diffracted) directions, and projects them onto the projected portion (front windshield 3). By using the system, the displayed image can be visually recognized by observers having different eye heights. Further, conventionally, for observers having different eye heights, the direction of the display light is changed by moving and / or rotating the optical system in the HUD device with an actuator or the like. It is also possible to abolish the actuator that drives such an optical system, and even if an actuator is provided, the movable range can be suppressed to a small size.

Further, in some embodiments, a protective layer may be provided on the outermost surface side of the holographic optical system 20. The protective layer can prevent the influence of deterioration of the storage stability of the holographic optical system 20 and / or prevent stains and scratches. The specific configuration of the protective layer is not limited, and known ones can be arbitrarily applied. For example, it can be formed of a water-soluble polymer, an organic material such as a resin, or an inorganic material such as inorganic glass. The specific method for forming the protective layer is not limited, and a known one can be arbitrarily applied. For example, the protective layer is a film material and is attached to the outermost surface side of the holographic optical system 20. It may be formed by applying a protective material to the surface. In this case, the light 10L from the display 10 is surface-reflected by the protective layer on the outermost surface side of the holographic optical system 20 (see the surface-reflected light 103 in FIG. 5). When the surface reflected light 103 reaches the position of the eyes of the observer 2, it is visually recognized as stray light that becomes noise other than the display image. Therefore, the surface reflected light 103 is prevented from facing the eye box to which the diffracted light of the holographic optical system 20 is distributed. In the surface reflected light 103, the incident angle θi3 and the reflected angle θr3 are equal to each other. Therefore, specifically, the uppermost eye box among the plurality of eye boxes to which the plurality of diffracted lights by the holographic optical system 20 are distributed so that the surface reflected light 103 does not face the eye box is preferable. The reflection angle θr3 is adjusted by adjusting the relative angle (incident angle θi3) between the display 10 and the holographic optical system 20 so as to face upward (or downward from the lowermost eyebox). You may adjust.

Further, in some of the present embodiments, the diffraction direction of the holographic optical system may be increased to distribute light to three or more regions (eye boxes).

Further, in the above embodiment, the first hologram 23 and the second hologram 24 are provided in parallel, but the present invention is not limited to this. The first hologram 23 and the second hologram 24 may be arranged non-parallel. FIG. 6 is a diagram showing an example in which the first hologram 23 and the second hologram 24 are arranged non-parallel. The angle of incidence θi1a on the hologram of the back surface side of the holographic layer 22 (first hologram 23 in FIG. 6) becomes the hologram of the layer on the front surface side of the holographic layer 22 (second hologram 24 in FIG. 6). It may be arranged so as to be larger than the incident angle θi1a of. In the example of FIG. 6, in order to arrange the first hologram 23 and the second hologram 24 in a non-parallel manner, a wedge-shaped intermediate layer 26 is provided between the first hologram 23 and the second hologram 24.

The intermediate layer 26 shown in FIG. 6 has light transmission and is typically transparent. The intermediate layer 26 contains, for example, a resin. The intermediate layer 26 may have a function of improving the adhesion between the first hologram 23 and the second hologram 24. The material of the intermediate layer 26 is not limited, and any known material can be applied. For example, a resin such as a thermoplastic resin can be used. The intermediate layer 26 may contain, for example, an acrylic resin, a urethane resin, an epoxy resin, a polyester resin, a vinyl resin, or a material obtained by combining these.

The present invention is not limited to these embodiments, and embodiments configured by appropriately combining the configurations of the respective embodiments are also within the scope of the present invention.

1 ... HUD device, 2 ... Observer, 3 ... Front windshield, 10 ... Display, 10L ... Incident light, 11 ... Light source, 11a ... Folded mirror, 12 ... Scanner, 13 ... Screen, 15 ... Synthetic light beam, 17 ... scanning beam, 20 ... holographic optical system, 21 ... substrate, 22 ... holographic layer, 23 ... first hologram, 24 ... second hologram, 26 ... intermediate layer, 100 ... display light, 101 ... first diffraction Light, 102 ... second diffracted light, 103 ... surface reflected light, 200 ... eye box, 201 ... first eye box, 202 ... second eye box, 301 ... first virtual image, 302 ... second virtual image, θi1 ... Incident angle, θi1a ... Incident angle, θi2 ... Incident angle, θi3 ... Incident angle, θr1 ... Reflection angle, θr2 ... Reflection angle, θr3 ... Reflection angle

Claims (6)

A display (10) that generates the light of the display image and
The light of the display image is incident, the light of the display image is diffracted in different directions, and the first virtual image of the display image is visible in the first diffracted light (201). 101) is distributed, and the second virtual image of the displayed image can be visually recognized, and the second diffracted light (102) is placed in the second region (202) arranged above the first region (201). With a holographic optical system (20) that distributes light,
Head-up display device. The holographic optical system (20) is a reflection type first hologram (23) that diffracts the light of the display image to generate the first diffracted light (101), and a surface from the first hologram (23). A partially reflective second hologram (which is arranged on the side and diffracts a part of the light of the display image to generate the second diffracted light (102) and transmits a part of the light of the display image. 24), including,
The head-up display device according to claim 1. The first hologram (23) has a diffraction angle (θr1, θr1a) larger than the incident angle (θi1, θi1a) of the light of the display image.
The second hologram (24) has a diffraction angle (θr2) that is larger than the incident angle (θi2) of the light of the display image and smaller than the diffraction angle (θr1, θr1a) of the first hologram (23).
The head-up display device according to claim 2. The first hologram (23) is arranged in parallel with the second hologram (24).
The head-up display device according to claim 2. The first hologram (23) is arranged so that the incident angle (θi1a) of the light of the displayed image is larger than the incident angle (θi2) of the light of the displayed image on the second hologram (24). The head-up display device according to claim 2. The holographic optical system (20) is
A protective layer (25) is further provided on the surface side of the diffracting functional layer.
The surface reflected light (103) in the protective layer (25) is arranged so as to face the lower side of the first region (201) or the upper side of the second region (202).
The head-up display device according to claim 1.

Images