JPH10142550A - Headup display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a headup display device capable of displaying plural images easy to see and having a small and inexpensive constitution. SOLUTION: This headup display device is composed so that signal light beams 311, 312 radiated from a displayer 21 are projected on a combiner 11 provided with a reflection hologram, displayed images 821, 822 are visualized by the diffracted light beams 321, 322 reflected to the line of sight of an observer in the combiner 11. The displayer 21 has plural radiating surfaces 221, 222 radiating signal light beams 311, 312 in different wavelength bands and the hologram composing the combiner 11 makes the plural optical wavelength bands of signal beams the selected wavelength areas of high diffraction efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a head-up display device, and more particularly to a head-up display device capable of simultaneously recognizing a plurality of display images within a visual field.

[0002]

2. Description of the Related Art In normal driving of an automobile, in order to confirm a speed display or the like, it is necessary to temporarily move a line of sight from an outside scene to instruments on an instrument panel. This operation is indispensable for driving, but is a very troublesome act. It is also said that frequent eye movements cause considerable fatigue for the driver. Therefore,
In recent years, there has been proposed a head-up display in which information necessary for driving such as speed and an external scene can be viewed simultaneously by using a combiner such as a holographic optical element (Japanese Patent Application Laid-Open No. 57-182540, actual application). Kaisho 6
No. 2-27835).

That is, as shown in FIG. 8, a head-up display 90 transmits optical information (signal light 31) radiated from a display 92 such as a CRT through an optical element 93 such as a lens or a hologram or directly. Is projected onto a combiner 91 such as a half mirror or a hologram, and is superimposed on an outside scene 83 so that a display image 82 is visually recognized by a viewer 85. As a result, when the display image 82 is viewed, the movement of the line of sight of the viewer 85 and the operation of adjusting the focus become unnecessary, and the visual recognition can be facilitated. Then, the hologram can provide complex various characteristics to the combiner 91 without increasing the size.

[0004] On the other hand, with the advancement of vehicle equipment and the development of information infrastructure, information that can be provided to drivers has been diversified. That is, conventionally, the information displayed by the head-up display is limited to the vehicle speed, the warning display, and the like.
Display of ICS (road traffic information communication system) information and the like is newly required for a head-up display. However, there is a limit to displaying a plurality of pieces of information on the head-up display simultaneously and easily in a single color.

Japanese Patent Application Laid-Open No. 2-186319 proposes a display device that displays an image in multiple colors and at different display positions. That is, a plurality of holograms having different characteristics are stacked to form a combiner, and the same number of display devices are arranged one-to-one with respect to the holograms. Then, each display emits signal light in the selected wavelength band of the hologram from a direction suitable for the characteristics of the corresponding hologram. as a result,
Images of different colors are displayed by the number of holograms. A liquid crystal display such as a full-color TFT type is known as a display which is relatively small and capable of multicolor display.

[0006]

[Problems to be solved]
The display device disclosed in Japanese Patent No. 86319 has a problem that the size of the display device is increased because a plurality of displays must be arranged by the number of holograms. In addition, it is difficult to adjust the position of the hologram and the combiner during mounting.

On the other hand, the method of obtaining a multi-color image using a liquid crystal display has a problem that it is difficult to obtain sufficient brightness because the light transmittance of the liquid crystal display element is low. Therefore, in order to increase the brightness of the image, it is necessary to use a high-luminance, high-power backlight, which increases the amount of heat generated and requires a measure for heat radiation. Furthermore,
Costs also rise significantly. The present invention has been made in view of such a conventional problem, and an object of the present invention is to provide a small and inexpensive head-up display device that can easily display a plurality of images.

[0008]

In the head-up display device according to the first aspect of the present invention, the display device has a plurality of radiating surfaces for radiating signal lights in different wavelength bands, and the hologram forming the combiner has a plurality of holograms. Is defined as a selected wavelength region (a wavelength region having high diffraction efficiency). Therefore, a plurality of display images (virtual images) corresponding to the signal lights in different wavelength bands are displayed. That is, a display image of the color of the first wavelength band is displayed by the hologram using the signal light of the first wavelength band as the selected wavelength region, and the hologram using the signal light of the second wavelength band as the selected wavelength region. The display images of the colors of the two wavelength bands are displayed, and the images of the number of the wavelength bands are sequentially displayed.

In this apparatus, the number of displays is one, and a plurality of radiating surfaces are formed on one display.
The device does not become large and can be manufactured at low cost. In addition, interference fringes are recorded on the plurality of holograms so that the virtual images are on the same line of sight of the viewer.

According to a second aspect of the present invention, a concave mirror records on the hologram and assigns a different value to the focal length of the concave mirror for each wavelength band of the signal light.
The position (depth) of each display image can be different. As a result, it is easier to distinguish each display image.
As for the display position, it is preferable that the minimum interval between the image forming positions is 20 mm or more and the maximum interval between the image forming positions is 100 mm or less. As will be described in detail later, when the interval between images is less than 20 mm, the difference in the sense of depth between the images is reduced, and it becomes difficult to classify the images. On the other hand, if it exceeds 100 mm, it becomes difficult to view a plurality of images without changing the adjustment of the eyes, and the eyes become tired.

The hologram having a plurality of selected wavelength regions may be formed by laminating a plurality of holograms. However, as described in claim 4, it is possible to form a hologram on one photosensitive member by multiple exposure. it can. In the case of a head-up display for a vehicle, it is preferable that each member of the combiner from the display is housed in a single case and arranged near the dashboard of the vehicle. By integrating the head-up display device into a single case, it is possible to manufacture the head-up display device on an independent manufacturing line, and adjustment and assembly are facilitated. Also, removal from the vehicle becomes easy, and maintenance and repair become easy.

In the case of a head-up display for a vehicle, the combiner can be arranged on the windshield. By doing so, the viewer (driver) can have a sense of unity between the vehicle and the head-up display device, and can feel the presence of the head-up display as natural.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 In this embodiment, as shown in FIG. 1, the signal lights 311 and 312 emitted from the display 21 are projected onto a combiner 11 having a reflection hologram, and the diffracted light 321 reflected by the combiner 11 is projected. , 322, the display image 8 as a virtual image
This is a vehicle head-up display device 1 configured to visually recognize 21, 822. The display 21 has two emission surfaces 221 and 222 for emitting signal lights 311 and 312 of different wavelength bands λ1 and λ2, respectively, and the hologram forming the combiner 11 includes a plurality of signal light wavelength bands λ1 and λ2. , Λ2 are selected wavelength regions having high diffraction efficiency.

In the hologram, a plurality of concave mirrors having different selected wavelength regions are recorded by multiple exposure.
The focal length of the concave mirror is the signal light wavelength band λ1, λ2
Each has a different value. All the members from the display 21 to the combiner 11 are housed in a single case 41 and arranged near the dashboard of the vehicle.
The following is a supplementary explanation for each.

As shown in FIG. 1, the head-up display 1 includes a display 21 provided inside a case 41.
And the mirror 1 for reflecting the signal lights 311 and 312 emitted from the display 21 in the direction of the hologram combiner 11
5 and a controller (not shown) for controlling the display 21 (liquid crystal element, backlight, etc.). The hologram combiner 11 is attached to the case 41 so as to be rotatable around the holder shaft 42, and can be raised and lowered on the upper surface of the case 41.
The angles can be adjusted so that the diffracted lights 321 and 322 travel in the direction of the eye.

As shown in FIG. 2, the display 21 has a liquid crystal display element 211 and a cold cathode tube 212 (light emission wavelength = 543 nm and 610 nm) serving as a backlight of the liquid crystal display element 211.
nm), a light diffusion plate 213, a color filter 214,
215. The liquid crystal display element 211 is a dot-type DSTN (Double STN) type liquid crystal element, and the color filters 214 and 215 are a low-pass filter 214 and a high-pass filter 215 having a cutoff wavelength of 575 nm.

The hologram constituting the combiner 11 is
This is a volume hologram, and interference fringes are formed by performing multiple exposures using a photopolymer as a photosensitive material. The hologram is formed by preparing an argon laser (514 nm) as an exposure light source, using the emitted light as reference light, irradiating the laser light onto a previously prepared master hologram, and using the diffracted light as object light, To form interference fringes. In the first step, the angle between the reference light and the object light is set so that the center value (the wavelength having the highest diffraction efficiency) of the selected wavelength region at the time of reproduction is a short wavelength (543 nm).

An aspheric concave mirror is recorded on the master hologram, and an off-axis aspheric concave mirror having a focal length of 168 nm is recorded on the created hologram. In the subsequent second step, the master hologram was changed and exposure was performed again to form another interference fringe. At this time, the incident angle of the reference light was changed, and the exposure was performed so that the central value (the wavelength having the highest diffraction efficiency) of the selected wavelength region at the time of reproduction became a longer wavelength (610 nm). Also,
With the changed master hologram, the focal length of the off-axis concave mirror is 163 mm.

As shown in FIG. 3, the hologram combiner 11 is provided on one surface of a transparent resin substrate 111 (signal light 31).
A hologram element 112 on which a concave mirror is recorded is formed on the entrance / exit surfaces of the light emitting elements 1 and 312, and an anti-reflection coat 113 is provided on the surface of the hologram element 112 to prevent external damage and a noise image due to reflected light. . Similarly, an antireflection coat 115 is formed on the opposite surface.

As shown in FIG. 1, the short wavelength (543 nm) signal light 311 emitted from the first radiation surface 221 of the display 21 uses the short wavelength formed in the first step as a selected wavelength region. Diffracted by the first hologram, the diffracted light 321 causes the viewer 85 to visually recognize a green display image 821 (virtual image). The signal light 312 of a long wavelength (610 nm) emitted from the second radiation surface 222 of the display 21 is diffracted by the second hologram having a longer wavelength formed in the second step and having a selected wavelength region. Diffracted light 32
2 allows the viewer 85 to visually recognize a red-orange display image 822 (virtual image).

Signal beams 311 and 31 incident on the hologram
Although the angle 2 is slightly different, the diffraction angles (reflection angles of the concave mirror) of the first hologram and the second hologram are slightly different, and the directions of the diffracted lights 321 and 322 are the same. Therefore, the viewer 85 can visually recognize the display images 821 and 822 on the same line of sight without moving the line of sight. Since the focal lengths of the concave mirrors recorded on the first and second holograms are different, the distance between the combiner 11 and the display images 821 and 822 differs by several tens of mm.
When the two display images 821 and 822 are simultaneously displayed, the viewer 85 can view the images 821 and 822 separately and three-dimensionally. In this example, the optical path length between the display 21 and the combiner 11 is 120 mm,
Incident angles of the signal lights 311 and 312 with respect to
The distance between the combiner 11 and the viewer 85 is about 90 cm.

As described above, the head-up display device 1 of the present embodiment can simultaneously display images 821 and 822 of different colors at different positions. And display 2
The number of 1 is one, and by forming a plurality of radiating surfaces 221 and 222 on one display 21, the device 1 can be reduced in size and can be manufactured at low cost. In addition, a plurality of radiating surfaces 2
21 and 222, the incident light (signal light 311 and 312) and the diffracted light 321, 32
2 are substantially the same, and the exposure optical system of the hologram corresponding to each wavelength (color) is substantially the same. Therefore, the hologram can be easily manufactured.

In this embodiment, a photopolymer is used as the photosensitive material. However, a silver salt, gelatin dichromate, photoresist or the like may be used. Further, in this example, multiple exposures were performed on one photosensitive member, but two holograms, one hologram forming a hologram in the first step and a separate hologram forming a hologram in the second step, were used.
The sheets may be attached. The display 21 uses the liquid crystal display element 211 and the cold cathode tube 212 as a backlight. However, if the display 21 is divided into regions having different wavelength bands by a filter, the light source is a fluorescent display tube or a light emitting diode. (LED). Also, the liquid crystal display element 211
May be a light source such as a halogen bulb or a xenon lamp.

Embodiment 2 This embodiment is different from Embodiment 1 in that two display images 821 and 821 are displayed.
Four types of hologram combiners 11 having different distances D (FIG. 4) between the hologram combiners 822 and 822 are manufactured.
22 is a test of the relationship between visibility (FIG. 6) and three-dimensional appearance (FIG. 5). That is, as shown in FIG.
The distance D generated between the image 82 and the image 822 is varied.
A sensory test was conducted on 1,822 for visibility and three-dimensional effect.

As shown in FIGS. 5 and 6, the image distance D (D
Is negative when the image 821 is in front of the image 822) in seven steps between minus 150 mm and plus 150 mm, and a sensory test was performed on three subjects. In both figures, ，, □, and Δ are symbols indicating the difference between subjects, and the vertical direction in FIG. 5 indicates the strength of the three-dimensional effect (separability between images), and the vertical direction in FIG. Show the visibility of

According to the results of these experiments, in the head-up display device 1 for a vehicle, by setting the absolute value of the distance D between images to be between 20 mm and 100 mm,
It has been found that the display images 821 and 822 can be distinguished naturally and three-dimensionally. Others are the same as in the first embodiment.

Third Embodiment As shown in FIG. 7, this embodiment differs from the first embodiment in that the hologram combiner 13 is replaced with the windshield 55 of the vehicle.
And another member such as the display 21 and the hologram combiner 13 are separately provided. The signal light 31 emitted from the display 21
1 and 312 directly enter the combiner 13 without passing through a mirror. The display 21 is embedded in the dashboard of the vehicle.

By arranging the combiner 13 in this manner, the viewer (driver) 85 is given a sense of unity between the vehicle and the head-up display device 1, and the presence of the head-up display is made more natural. You can feel it. Note that, as in the first embodiment, the display 21
A mirror for changing the optical path may be arranged between the mirror and the combiner 13. By arranging the mirror, the degree of freedom for the position of the display 21 is increased. Others are the same as the first embodiment.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of a head-up display device according to a first embodiment.

FIG. 2 is a perspective view of the display device according to the first embodiment.

FIG. 3 is a sectional view of a combiner according to the first embodiment.

FIG. 4 is a diagram showing a positional relationship between a viewer and a display image in a sensory test performed in a second embodiment.

FIG. 5 is a diagram showing a result of a sensory test (three-dimensional effect of an image) performed in the second embodiment (part 1);

FIG. 6 is a diagram showing the results of a sensory test (image legibility) performed in Embodiment 2 (part 2).

FIG. 7 is a system configuration diagram of a head-up display device according to a third embodiment.

FIG. 8 is a system configuration diagram of a conventional head-up display device.

[Explanation of symbols]

 1. . . Head-up display device, 11, 13. . . Hologram combiner, 21. . . Indicators, 221, 222. . . Radiation surface, 311, 312. . . Signal light, 321,322. . . Diffracted light, 821, 822. . . Display image,

Claims (6)

[Claims] A head configured to project a signal light emitted from a display onto a combiner provided with a reflection hologram, and to visually recognize a display image by diffracted light reflected in a line of sight of a viewer in the combiner. An up display device, wherein the display has a plurality of emission surfaces for emitting signal lights in different wavelength bands, respectively, and the hologram forming the combiner is configured to convert the plurality of signal light wavelength bands into diffraction efficiency. Head-up display device, characterized in that the selected wavelength region is high. 2. The head-up display according to claim 1, wherein a concave mirror is recorded on the hologram, and a focal length of the concave mirror has a different value for each signal light wavelength band. apparatus. 3. A minimum distance between image forming positions of a display image for different signal light wavelength bands is 20 m.
m, and the maximum distance between image forming positions of display images for different signal light wavelength bands is 100 mm or less. 4. The head-up display device according to claim 1, wherein the hologram of the combiner has a plurality of selected wavelength regions formed by multiple exposure. 5. The vehicle according to claim 1, wherein all members from the display to the combiner are housed in a single case and arranged near a dashboard. Head-up display device. 6. The head-up display device for a vehicle according to claim 1, wherein the combiner is disposed on a windshield.