JP2867423B2 - Head-up display device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a head-up display device, and more particularly, to a head-up display device which is artificially created with image information such as a natural scene in front through a hologram optical element having transparency. The present invention relates to a head-up display device suitable for simultaneously observing both pieces of display information.

(Prior Art) Display information from a display device using an optically transparent light beam coupling element such as a multilayer film reflection surface or a hologram optical element,
2. Description of the Related Art A display device in which image information such as natural scenery of the outside world is spatially superimposed and observed in the same field of view is generally called a head-up display device, and is widely used in various fields.

Conventionally, various display devices using this head-up display device in various vehicles such as a cockpit of an aircraft have been proposed.

When such head-up display devices are used by persons of various sizes, it is desired that observation can be performed in a better state than at various positions (directions).

For example, when adjusting a display optical system in response to a change in seat height, seat position, and the like in a driver's seat of a car when a half mirror or a dichroic mirror is used as a light beam coupling element, Japanese Utility Model Laid-Open No. 61-31931 discloses a half mirror. A method has been proposed in which the position is adjusted.

Japanese Patent Application Laid-Open No. 61-188236 proposes a method in which the angle of a bending mirror provided in an optical path is adjusted.

Japanese Utility Model Application Laid-Open No. 62-46228 proposes a method in which the entire display optical system is rotated.

(Problems to be Solved by the Invention) When a hologram diffraction grating element is used instead of a half mirror as a light beam coupling element, an outside scene can be observed brightly, and at the same time, an image of a display element composed of a light beam having excellent monochromaticity. The method has a feature that information can be reflected at a high diffraction efficiency and can be observed brightly. In order to adjust the observation position, various problems occur in each of the above-described methods.

Next, a problem that occurs when the observation position (observation direction) is changed using a reflection volume phase type diffraction grating as an example will be described with reference to FIGS.

FIG. 5 shows a state where the reflection volume phase type diffraction grating 35 is used to observe from the directions of the reflection diffraction angle θ ₄ = 50 (solid line) and the angle θ ₄ ′ = 45 ° (dashed line).

Unlike the half mirror, the diffraction grating 35 generates a large amount of diffracted light in the diffraction direction satisfying the black condition, and at the same time, shifts the center wavelength.

The diffraction grating shown in the figure is mainly composed of, for example, poly (N-vinylcarbazole) as a photosensitive material, has an average refractive index of 1.67, an in-plane grating pitch of 1.92 μm, and a grating tilt angle.
4.94 ゜.

Light having a wavelength of 510 nm, on which a light beam enters the diffraction grating 35 at an incident angle θ ₃ = 30 °, is reflected and diffracted, and the reflected diffraction angle θ ₄ = 50.
Proceed in the direction of ゜. Light having a wavelength of 518 nm incident at an incident angle θ ₃ ′ = 25.9 ° is reflected and diffracted, and the reflected diffraction angle θ ₄ ′ = 45.
Proceed in the direction of ゜.

Figure 6 is the spectral energy of suitable fluorescent display tube to combine a display device which changes the center wavelength of the observation direction at this time (Z _n O, P15-G1 fluorescers whose main composition to Z _n) It shows the distribution. By setting the center wavelength of the diffraction grating near the peak wavelength of the spectral energy distribution of the phosphor (the wavelength at which the amount of diffracted light is maximized), the display can be observed brightly even if the observation position fluctuates up and down and back and forth. It becomes possible.

In the display device having such a configuration, the wavelength width of the light used ranges from 10 nm to 50 nm due to the wavelength characteristics of the diffraction grating 35, and as a result, the display image is blurred due to the wavelength dispersion. As an example of a means for correcting such chromatic dispersion, U.S. Pat.
No. 13200 proposes a method in which two diffraction gratings similar to the diffraction grating 35 are arranged in parallel with each other.

However, although this method can achieve aberration correction, it requires a long optical path length from the display to the diffraction grating, which causes a problem that the entire apparatus becomes large, and there is a problem that office machines and automobiles placed on a desk are required. It is not very desirable for the dashboard of the driver's seat because it is desired that the volume be as small as possible.

INDUSTRIAL APPLICABILITY The present invention can be efficiently accommodated in a small volume, has less blur of a display image caused by wavelength dispersion of a diffraction grating, and easily adjusts an observation position (observation direction) to various positions (directions). It is an object of the present invention to provide a head-up display device capable of performing such operations.

(Means for Solving the Problems) A head-up display device of the present invention includes a display for displaying information with a light beam having a predetermined wavelength width, a first diffraction grating for diffracting and deflecting the light beam from the display device, In a head-up display device including a second diffraction grating that reflects and diffracts a light beam from the first diffraction grating and has a light transmitting property, the angle of the first diffraction grating can be changed and the angle can be changed. An adjusting means having a mechanism for changing the optical path length by moving the first diffraction grating in accordance with the change is provided.

Further, the head-up display device of the present invention comprises a display for displaying information with a light beam having a predetermined wavelength width, a first diffraction grating for diffracting and deflecting the light beam from the display, In a head-up display device including a second diffraction grating that reflects and diffracts a light beam and has a light transmitting property, an optical path length is changed by moving the first diffraction grating, and the optical path length is changed. And adjusting means having a mechanism for changing the angle of the first diffraction grating.

(Embodiment) FIG. 1 is a schematic view of a main part of an optical system according to an embodiment of the present invention. In the figure, a light beam 32 emitted from the surface of a display 31 such as a CRT or a fluorescent tube is reflected by a first reflection type light beam provided on the surface of a substrate 11.
The light beam 33 is reflected and diffracted by the diffraction grating 11 to become a light beam 33, and is incident on a reflection volume phase type second diffraction grating 35 disposed between the transparent substrates 34 and 37. The light beam 36 reflected and diffracted by the second diffraction grating 35 enters the pupil 51 of the observer, and the display on the display 31 is observed together with the background.

In the present embodiment, the first diffraction grating 11 may be a reflection type diffraction grating, a surface relief grating formed by machining, a relief grating formed on the back surface of a transparent substrate, a reflection volume phase type diffraction grating, or the like. In addition, the arrangement of the grating can be made to have a function such as a part of a zone plate having a condensing property or a cylindrical lens other than the linear equal-interval grating. And a holographic pattern formed by two-beam interference from a laser. In addition, the substrate may have a convex surface, a concave surface, or a cylindrical surface other than a flat surface.

In this embodiment, since a sufficient function can be achieved by using a linearly-spaced grating, the following description will be made on the case where a planar linearly-spaced grating is used as the first diffraction grating.

In this embodiment, the grating pitch P1 required for the first diffraction grating 11 is 0.82 μm. The light beam 33 is incident on the second diffraction grating 35 at an incident angle θ ₃ = 25 ° and is reflected and diffracted at an angle θ ₄ = 45 °. Here, the in-plane pitch P2 of the diffraction grating 35 is 1.91 μm, and various materials such as poly (N-vinylcarbazole), dichromated gelatin, and gum arabic can be used as a material constituting the diffraction grating. Can be used. The present invention has a configuration in which blurring due to color dispersion of the displayed content to be observed is prevented.

 Next, the technical contents will be briefly described.

Now, the display 31 has a finite wavelength spread of, for example, a half-value width of about 10 nm to 300 nm, and the corresponding reflection type diffraction grating 35 also has a wavelength characteristic of a half-value width of about 10 nm to 100 nm.

The most noticeable decrease in image quality when viewing display contents displayed by combining such a light source and a diffraction grating is image blur in the vertical direction of the image.

The correction of the vertical blur is performed as follows.
Now, consider light having a wavelength slightly longer than the center wavelength (for example, 515 nm for 510 nm). This wavelength light is traced back along the optical path 36 to calculate a virtual light flux. When these virtual light fluxes intersect with the result of the ray tracing of the center wavelength on the display 31, an image in which the color shift in the vertical direction has been corrected is observed from the observation position 51. At this time, the condition under which the color shift can be corrected is that the distance from the display 31 to the first diffraction grating 11 is l1, the distance from the first diffraction grating 11 to the second diffraction grating 35 is l2, Assuming that the incident angle and the diffraction angle of the light beam on the first diffraction grating 11 are θ ₁ and θ ₂ , and the incident angle and the diffraction angle on the second diffraction grating 35 are θ ₃ and θ ₄ Given by Here, the pitches P1 and P2 of the diffraction grating are given by P1 = λ ₀ / | sin θ ₁ −sin θ ₂ | P ₂ = λ ₀ / | sin θ ₃ −sin θ ₄ |

As a result, the display 31 may be fixed, and the first diffraction grating 11 may be changed so as to satisfy, for example, the following conditional expression.

(B) Reference position Incident angle θ ₁ = 45 °, diffraction angle θ ₂ = 5 °, incident angle θ ₃ = 30 °, diffraction angle θ ₄ = 50 °, center wavelength 510 nm, l2 / l1 = 2 (b) Observation When the position is moved downward Incident angle θ ₁ = 41 °, diffraction angle θ ₂ = 1.7 °, incident angle θ ₃ = 25.9 °, diffraction angle θ ₄ = 45 °, center wavelength 518 nm, l2 / l1 = 1.92 (c ) When the observation position moves upward: Incident angle θ ₁ = 49 °, diffraction angle θ ₂ = 8.3 °, incident angle θ ₃ = 33.9 °, diffraction angle θ ₄ = 55 °, center wavelength 502 nm, l2 / l1 = 2.17 FIG. 2 is a diagram showing a first example according to the change of the observation direction in the present invention.
FIG. 4 is an explanatory diagram of an embodiment of an adjusting means for adjusting an optical path length and a reflection diffraction angle by changing the diffraction grating 11 of FIG.

In the figure, a pin 22 and a pin
23 have been planted. The pin 22 is fitted in a long groove 21 provided in the guide plate 20 and moves in the long groove 21. On the other hand, the pin 23 is pressed against the cam surface 19 of the guide plate 20 by a pressing mechanism (not shown) and slides along the cam surface 19.

Now, the pin 22 is pin 23 when moving to the position of the pin 22 ₁ is moved to the position of the pin 23 _1. The pin 22 is a pin 23 when moving to the position of the pin 22 ₂ is moved to the position of the pin 23 _2.

In this embodiment, the rotation angle is set as an arbitrary function with respect to the movement amount of the diffraction grating 11 by appropriately configuring the shape of the cam surface 19 as a function. In this embodiment, when rotating the diffraction grating 11 at a large angle, a commonly used mirror turning mechanism may be used.

FIG. 3 is a schematic view of another embodiment as an adjusting means for rotating the diffraction grating 11 according to the present invention. In the figure, substrate 10
Is formed with a reflection type diffraction grating 11. A pin 18 is attached to a support member (not shown) at the other end of the substrate 10,
The substrate 10 is rotated around the pins 18 as a rotation axis. Thereby moving the diffraction grating 11 position 11 _1, or at positions 11 _2.

The present embodiment has a feature that the angle of the diffraction grating can be satisfactorily adjusted with high reliability with a simple configuration.

In the present embodiment, the relationship between the optical path length and the rotation angle can be finely adjusted by removing the position of the pin 18 in the vertical direction from the surface of the diffraction grating 11.

FIG. 4 is a schematic view of another embodiment as an adjusting means for adjusting the diffraction grating 11 according to the present invention.

In the figure, a reflective diffraction grating 11 is formed on a substrate 10 and is attached to a link component 62. Element
Non-parallel links are constituted by 60, 61, 62 and 63. Member 6
1 member 62 when moving to the position of the member 61 ₁ is moved to the position of the member 62 _1, the diffraction grating 11 is moved to the position of the diffraction grating 11 _1. Thereby, the center position of the diffraction grating 11 is moved and the rotation angle is adjusted.

(Effects of the Invention) According to the present invention, a light flux from image information on a display surface is diffracted through two diffraction gratings of a predetermined shape and a volume phase type diffraction grating to provide a background scenery and space. Observation position (observation direction) of observer when observing both by overlapping
By adjusting the chromatic aberration variation caused by the change of the center wavelength caused by the variation in the optical path length and the rotation angle by adjusting means provided on the diffraction grating, the display image is displayed in good condition without blurring of the display image due to wavelength dispersion. A head-up display device capable of observing image information on a surface can be achieved.

[Brief description of the drawings]

FIG. 1 is a schematic view of a main part of an optical system according to an embodiment of the present invention.
3 and 4 are schematic views of an embodiment of the adjusting means for adjusting the diffraction grating of FIG. 1, FIG. 5 is an explanatory view showing a diffraction state of a volume phase type diffraction grating, and FIG. It is explanatory drawing of the spectral energy distribution of the display which concerns on invention. In the figure, 31 is a display, 11 is a first diffraction grating, 10 and 34 are substrates, 35 is a second diffraction grating, 35 and 37 are transparent substrates, 51 is an observer, and 35 is a volume phase type diffraction grating. It is.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Nobuo Kushibiki 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References JP-A-63-194222 (JP, A) JP-A-64 -18120 (JP, A) Actually open 64-6431 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) G02B 27/02

Claims (2)

(57) [Claims] 1. A display for displaying information with a light beam having a predetermined wavelength width, a first diffraction grating for diffracting and deflecting a light beam from the display device, and reflecting and diffracting a light beam from the first diffraction grating; In a head-up display device including a second diffraction grating having optical transparency, the angle of the first diffraction grating can be changed, and the first diffraction grating is moved according to the angle change. A head-up display device comprising an adjusting means having a mechanism for changing an optical path length. 2. A display for displaying information with a light beam having a predetermined wavelength width, a first diffraction grating for diffracting and deflecting the light beam from the display device, and reflecting and diffracting the light beam from the first diffraction grating; In a head-up display device including a second diffraction grating having light transmissivity, the first diffraction grating is moved to change an optical path length, and the first diffraction grating is moved in response to the optical path length change. A head-up display device comprising an adjusting unit having a mechanism for changing the angle of a diffraction grating.