JPH06202035A - Head-up display device - Google Patents

Abstract

PURPOSE:To reduce the overall size of the device and excellently compensate the chromatic aberration by using a 1st and a 2nd diffraction grating and properly setting the arrangement relation among respective elements. CONSTITUTION:When equations I hold for the incidence angles and diffraction angles of the diffraction gratings, the distances between respective elements, etc., the condition shown by an equation II is satisfied. In the equations, lambdao is center wavelength, L1a the distance from the center of a display unit 31 to the center of the 1st diffraction grating 11, L2a the distance from the center of the diffraction grating 11 to the center of the 2nd diffraction grating 35, theta1a and theta2a the incidence angle and diffraction angle of luminous flux on the center of the diffraction grating 11, and theta3a and theta4a the incidence angle and diffraction angle of luminous flux on the center of the diffraction grating 35. Further, lambdagamma is the wavelength of the luminous flux, Rgamma1 and Rgamma 2 the distances the positions of spot light sources A and B emitting pieces A and B of luminous flux to a photosensitive material, and thetagamma1 and thetagamma2 the angles of incidence of the pieces A and B of luminous flux in the center of the photosensitive material when the diffraction grating 11 is formed. They are minus when the diffraction grating 11 is in converging operation and plus when in diverging operation.

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 image information such as natural scenery in front and display information artificially created through a diffraction grating such as a transparent hologram optical element. The present invention relates to a head-up display device (hereinafter also referred to as “HUD”) suitable for observing both information items at the same time.

[0002]

2. Description of the Related Art Display information from a display device and image information such as a natural scenery of the outside world are spatially distributed within the same field of view by using an optically transparent light flux coupling element such as a multilayer film reflecting surface or a hologram optical element. A display device for superimposing and observing is generally called a head-up display device and is often used in each field.

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

When an image is displayed by using a diffraction grating optical element as the light beam coupling element, the display is made multicolored, or when an ordinary inexpensive fluorescent tube is used as the above-mentioned display device, it is generated by the diffraction grating optical element. There is a problem that the color of the display image is blurred or the display image is blurred due to the chromatic aberration.

One method for solving this problem is proposed in, for example, Japanese Patent Application Laid-Open No. 1-296214.

FIG. 3 is a schematic view of a head-up display device (HUD) proposed in the publication.

In FIG. 1, a light beam 32 emitted from a display 31 is reflected and diffracted by a reflection type diffraction grating 11 on a substrate 10 to become a light beam 33, which is a reflection type light beam disposed between transparent substrates 34 and 37. The light enters the volume phase type diffraction grating 35.

Light flux 3 reflected and diffracted by the diffraction grating 35
6 enters the observer's pupil 51. Thereby, the observer simultaneously observes the display information on the display 31 and the image information 101 behind the diffraction grating 35 in the same field of view through the diffraction grating 35.

At this time, as shown in the figure, the distance between the display 31 and the first diffraction grating 11 is L1, the distance between the first diffraction grating 11 and the second diffraction grating 35 is L2, The in-plane pitches of the first diffraction grating and the second diffraction grating are P1 and P, respectively.
2, the incident angle and the diffraction angle of the light beam at the center of the first diffraction grating 11 are θ1 and θ2, respectively, the incident angle and the diffraction angle of the light beam at the center of the second diffraction grating 35 are θ3 and θ4, respectively. When the central wavelength of the light flux of is λ ₀

[0010]

[Equation 3] Here, P1 = λ ₀ / | are set each element such that relation is established _{| sinθ1 -sinθ2 | P2 = λ 0} / | sinθ4 -sinθ3.

Thus, the holographic display device capable of performing good observation by correcting the blurring of the image in the vertical direction of the observation direction due to the color dispersion of the diffraction grating 35 is achieved.

[0012]

If a diffraction grating having a straight line interval is used as a diffraction grating used for correcting chromatic aberration that occurs when a diffraction grating optical element is used as a light beam coupling element in a HUD device, the center of the grating is used. In the vicinity, chromatic aberration can be sufficiently corrected.

On the other hand, it is preferable to use a diffraction grating having an optical power as the diffraction grating for correcting chromatic aberration because the burden of correction of various aberrations is reduced, the optical path length is shortened, and the entire apparatus is downsized.

However, in general, a diffraction grating having an optical power is satisfactorily corrected for chromatic aberration in a region of the diffraction grating which can be regarded as linear equal intervals in the vicinity of the optical axis. For this reason, the chromatic aberration of the light beam that enters and is diffracted in a region far away from the optical axis is not sufficiently corrected, and some aberration remains.
As a result, there is a problem that image blurring occurs at the upper end and the lower end of the display image.

According to the present invention, the first diffraction grating and the second diffraction grating having optical power display information displayed by visible light having a wavelength width.
When the display is performed at a predetermined position behind the second diffraction grating using the above diffraction grating, by appropriately setting the arrangement relationship of each element, the overall size of the device can be reduced and the chromatic aberration over a wide range of the entire screen can be achieved. It is an object of the present invention to provide a head-up display device capable of satisfactorily correcting both the display information of the display and the image information behind the second diffraction grating, such as a scene, in the same field of view. .

[0016]

A head-up display device of the present invention diffracts and deflects a light beam from a display device, which displays information with a light beam having a center wavelength λ _{0 and} a predetermined wavelength width, by a first diffraction grating, and then Image information behind the second diffraction grating is formed by diffracting and deflecting the second diffraction grating having a light-transmitting property to form display information on the display at a predetermined position behind the second diffraction grating. When observed in the same field of view by spatially overlapping with, the distance from the center of the display to the center of the first diffraction grating is L1a,
The distance from the center of the first diffraction grating to the center of the second diffraction grating is L2a, the incident angle of the light beam to the center of the first diffraction grating and the diffraction angles from it are respectively θ1a and θ2a, and the second diffraction grating. The incident angle of the light beam to the center and the diffraction angle from it are θ
3a, θ4a, the first diffraction grating is formed by recording the interference of two light beams on a sensitive material, and the wavelength of the light beam when forming the first diffraction grating at this time is λγ, Point light source A that emits one of two light fluxes A when forming a diffraction grating
Is Rγ1, the distance between the center of the photosensitive material and the center of the photosensitive material is Rγ1, the distance between the position of the point light source B that emits the other luminous flux B and the photosensitive material is Rγ2, and the sensitivity of the luminous flux A and the luminous flux B when the first diffraction grating is formed. The incident angles at the center of the material are θγ1 and θγ2, respectively, when the first diffraction grating has a converging action, with a minus sign, and when it has a diverging action, with a plus sign,

[0017]

[Equation 4] When

[0018]

[Equation 5] It is characterized by satisfying the following condition.

[0019]

EXAMPLE 1 FIG. 1 is a schematic view of a main part of an optical system of Example 1 of the present invention.

In this embodiment, a head-up display device (HUD) is applied to, for example, a driver's seat of an automobile.

The outline of the optical arrangement of this embodiment is similar to that of the conventional HUD shown in FIG. 3, but this embodiment uses the first diffraction grating 1
1 has an optical power, and as a result, the conditions such as the distance between each element, the incident angle of the light flux to each diffraction grating, and the diffraction angle from it differ.

Next, the features of each element of this embodiment are shown in FIG.
It will be explained though it partially overlaps with the HUD.

In the figure, an indicator 3 such as a CRT or a fluorescent tube is shown.
The visible light flux 32 having a predetermined wavelength width radiated from one surface is reflected and diffracted by the reflection-type first diffraction grating 11 having a predetermined power (refractive power) provided on the surface of the substrate 10. The light beam 33 becomes a light beam 33 and is incident on a second reflection volume phase type 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 observer's pupil 51. At this time, the display information on the surface of the display 31 is formed at a predetermined position behind the second diffraction grating 35.

As a result, the display information on the surface of the display 31 is spatially superposed on the image information 101 such as the background behind the second diffraction grating 35 and observed in the same visual field.

Reference numeral 29 is a light-shielding plate, which prevents the light flux from the display 31 from being directly observed, and allows external light to be displayed on the display 31.
The amount of light incident on is reduced so that the display information on the display 31 can be observed well.

In this embodiment, the first diffraction grating 11 is a reflection type diffraction grating and is a reflection volume phase type diffraction grating.
It is manufactured by holographic pattern formation by two-beam interference from a laser.

As the substrate 10 used in this embodiment, a flat substrate is used, or a convex surface, a concave surface, a cylindrical surface or the like can be used.

Next, an example of a method of correcting chromatic aberration of the optical system and a method of manufacturing the first diffraction grating 11 in this embodiment will be described.

FIG. 2 shows the first diffraction grating 11 according to this embodiment.
It is explanatory drawing of the optical system at the time of manufacturing.

In the figure, light of wavelength λγ from a laser light source (not shown) is split into two lights by a half mirror (not shown). These respective light beams are converted into light beams 43 and 44 by the beam expanders 41 and 42, respectively (note that the divergence points from the beam expanders 41 and 42 correspond to the positions of the point light sources).

Of these, the light flux 43 is incident on the photosensitive material 46 coated or held on a support 45 such as a transparent glass substrate from the support 45 side at an incident angle θγ1. Other luminous flux 4
4 directly enters the photosensitive material 46 from the side opposite to the incident direction of the light beam 43, that is, from the photosensitive material 46 side at an incident angle θγ 2.

The photosensitive material 46 used at this time may be of various types such as DCG (dichromated gelatin) and photopolymer.

In this embodiment, a photopolymer having a refractive index of 1.5 is used. In the present embodiment, the incident angles θγ1 and θγ2 of the light beams 43 and 44 are 38.13 ° and 7 respectively.
It is set to 5.07 °. Beam expander 41
Distance from the (42) to the center of the photosensitive material 46 Rγ1, R
γ2 was selected as Rγ1 = 500 mm and Rγ2 = ∞.

When the power (refractive power) Da of the diffraction grating produced at this time, that is, the hologram, is defined as follows,

[0036]

[Equation 6] In this embodiment, since the recording laser light is light from the argon ion laser with a wavelength of 514.5 nm, Da = 2.4050 (mm ⁻² ).

Next, as the second diffraction grating 35, a reflection type diffraction grating of an evenly spaced linear grating having an in-plane grating pitch P2 of P2 = 2.7108 μm is used to construct the HUD system of Example 1 shown in FIG. did. At this time, as the light flux from the display 31, a light flux having an oscillation center wavelength λ ₀ of λ ₀ = 540 nm is used. Specifically, a fluorescent display tube or a liquid crystal display device having a certain emission wavelength width was used.

In this embodiment, the incident angle θ3a and the diffraction angle θ4a of the display light on the second diffraction grating 35 are θ3, respectively.
a = 45 °, θ4a = 65 °, the incident angle θ1a and the diffraction angle θ2a at the first diffraction grating 11 are θ1a = 60, respectively.
And θ2a = 30 °, the first diffraction grating 11 and the second diffraction grating 11
The distance between the diffraction grating 35 and the diffraction grating 35 is L2a = 150 mm.

Next, the chromatic aberration correction method and the conditions of the optical arrangement in this embodiment will be described.

Now, as shown in FIG. 1, to the observer's pupil 51,
It is assumed that the light beam 36 having the wavelength λ ₀ from the display 31 is incident.

At this time, when the wavelength width of the light beam from the display unit 31 has a wavelength spread of λ ₀ ± Δλ, the light beams of λ ₀ -Δλ, λ ₀ , and λ ₀ + Δλ respectively enter the pupil 51 of the observer. If so, the display image (display information) on the display unit 31 does not cause blurring due to color shift.

Therefore, in the above arrangement, λ ₀ ± Δλ
Back light ray tracing is performed for the luminous flux of
The distance L1a between the diffraction grating 11 and the diffraction grating 11 may be obtained.

Now, when inverse ray tracing is performed on a light beam having a wavelength of 545 nm with Δλ = 5 nm, a light beam 36 having a wavelength of 545 nm is diffracted by the second diffraction grating 35 at an angle different from the diffraction angle θ3a of the light beam 33 having a wavelength of 540 nm. ′
Becomes

This light ray 33 'is further diffracted by the first diffraction grating 11 to become a light ray 32'. At the intersection of this light ray 32 'and the light ray 32 having the wavelength λ ₀ = 540 nm, the display 3
If the display surface of No. 1 is provided, the light flux of the wavelength λ ₀ = 540 nm and the light flux of the wavelength λ ₀ + Δλ = 545 nm emitted from the display 31 coincides with the case where they are emitted from the second diffraction grating 35. It is incident on the pupil 51, and as a result, no chromatic aberration occurs.

As a result of performing this back ray tracing using the above variables, if the following conditions are satisfied as the relationship between the variables, chromatic aberration can be corrected well.

[0046]

[Equation 7] here

[0047]

[Equation 8] P1a = λ ₀ / | sin θ1a-sin θ2a | P2a = λ ₀ / | sin θ3a-sin θ4a |, where the sign is + when the first diffraction grating 11 has a concave mirror action and + when it has a convex mirror action. .

The layout condition of this embodiment is again λ ₀ = 540.
nm, θ1a = 60 °, θ2a = 30 °, θ3a = 45
°, θ4a = 65 °, L2a = 150 mm, Da =
2.4050 (mm ^-2 ), and P1a = 1.4753μ
Substituting m, P2a = 2.7108 μm into the above relational expression to obtain the distance L1a between the display 31 and the first diffraction grating 11, it must be L1a = 65.79 mm.

The first diffraction grating 11 in the present invention is used so as to have a function as a concave mirror, so that the reference numeral is-.

Here, in the conventional arrangement of the HUD in which the chromatic aberration is corrected by the applicant of the present application, when the conditional expression disclosed in Japanese Patent Laid-Open No. 1-296214 is used, L1 = 9.
It must be 9.94 mm.

On the other hand, as shown in this embodiment, the first
Since the diffraction grating 11 has a power, the distance L1a
Has an effect that L1a = 65.79 mm, the distance between the display 31 and the first diffraction grating 11 can be shortened, and image blurring due to chromatic aberration does not occur.

Conversely, when the first diffraction grating 11 has power, if the HUD is constructed by the conditional expression for chromatic aberration correction of the conventional example, the aberration is favorably corrected near the center of the optical axis. In the surrounding area, the correction was insufficient, causing image blurring due to color misregistration.

On the other hand, according to the present embodiment, it is shown that the chromatic aberration is similarly favorably corrected not only in the optical axis center but also in the optical axis periphery.

Next, a second embodiment of the present invention will be described.
The optical arrangement is basically the same as that of the first embodiment shown in FIG.

The power (refractive power) of the first diffraction grating according to the present embodiment is made slightly weaker than the power of the first diffraction grating used in the first embodiment of FIG.

In the present embodiment, when the first diffraction grating 11 is manufactured, the incident angle θ of the light beam 44 shown in FIG.
γ2 is θγ2 = 75.07 °, and the distance Rγ2 is Rγ2 =
It is set to 500 mm and a divergent light flux is used.

At this time, the power Da of the first diffraction grating 11 is Da = 2.1470 (mm ^-2 ) by using the above-mentioned defining equation.

By substituting this into the above-mentioned conditional expression for chromatic aberration correction, the distance L1a is L1a = 68.29 mm. Therefore, in the present embodiment, the above-mentioned numerical values are θ1a = 60 °, θ2a = 30 °, θ3a = 45 °, θ.
4a = 65 °, L1a = 68.29 mm, L2a
= 150 mm, the HUD device is configured to satisfactorily correct chromatic aberration.

As described above, in Examples 1 and 2 of the present invention,
The description has been given of the case where the reflection type diffraction grating having the in-plane grating pitch of linear equal intervals is used as the second diffraction grating. However, even if this diffraction grating has power, the idea of the present invention and the conditional expression for chromatic aberration correction are It is possible to realize a HUD device that is satisfied and is well corrected for chromatic aberration.

[0060]

According to the present invention, the display information displayed by visible light having the wavelength width as described above is used by using the first diffraction grating and the second diffraction grating having the optical power. When displaying at a predetermined position behind the diffraction grating, by appropriately setting the positional relationship of each element, the overall size of the device can be reduced and the chromatic aberration can be satisfactorily corrected over a wide range of the entire screen. A head-up display device capable of satisfactorily observing both display information and image information behind the second diffraction grating, such as a scene, can be achieved.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of a first embodiment of the present invention.

FIG. 2 is an explanatory view of a method for manufacturing the diffraction grating of FIG.

FIG. 3 is a schematic view of a main part of a conventional head-up display device.

[Explanation of symbols]

 10 Substrate 11 First Diffraction Grating 31 Display 34, 37, 45 Transparent Substrate 35 Second Diffraction Grating 51 Pupil 41, 42 Beam Expander 46 Sensitive Material

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Susumu Matsumura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (1)

[Claims] 1. A first diffraction grating diffracts and deflects a light flux from a display device on which information is displayed with a light flux having a center wavelength λ _{0 and} a predetermined wavelength width, and then diffracted and deflected by a second diffraction grating having a light-transmitting property. When the display information of the display is imaged at a predetermined position behind the second diffraction grating and is spatially superposed with the image information behind the second diffraction grating and observed in the same visual field. , The distance from the center of the display to the center of the first diffraction grating is L1a, the distance from the center of the first diffraction grating to the center of the second diffraction grating is L2a, and the incidence of the light beam on the center of the first diffraction grating Angles are θ1a and θ2a, respectively, and the incident angle of the light beam to the center of the second diffraction grating and the diffraction angles from it are θ3, respectively.
a, θ4a, the first diffraction grating is formed by recording interference of two light beams on a sensitive material, and the wavelength of the light beam when forming the first diffraction grating at this time is λγ, When forming the diffraction grating, the distance between the position of the point light source A that emits one of the two light fluxes A and the center of the photosensitive material is Rγ1, and the distance between the position of the point light source B that emits the other light flux B and the photosensitive material. Rγ2, incident angles of the light beam A and the light beam B at the center of the photosensitive material when forming the first diffraction grating are θγ1 and θγ2, respectively, when the first diffraction grating has a converging action, a minus sign, a divergence action Let be a plus sign when When A head-up display device characterized by satisfying the following conditions.