JP2993319B2 - Display device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for displaying display information through a virtual image through an optical system, and more particularly to a display device which can be compact and can be mounted in a small space.

[0002]

2. Description of the Related Art A conventional display device is disclosed, for example, in Japanese Patent Application Laid-Open No. 62-31531.
In these apparatuses, an optical system for projecting driving information displayed on a driving information display section is constituted by a reflecting (or diffractive) member and a transflective (or transflective) member, and the transflective (or transflective) member is provided. Reflection (or diffraction) of a member
By arranging it between the member and the operation information display unit, compared to a lens system device that projects using an optical lens,
The optical path length can be lengthened despite its small size.

FIGS. 6 and 7 show examples of the above-mentioned conventional vehicle display device. 6 includes a combiner 602 mounted on a windshield 601 and a driving information display body 60 disposed in a dashboard 603.
4, an optical system (projector) including a plane mirror 605 and a semi-transmissive concave mirror 606. The display light emitted from the operation information display body 604 is transmitted to the semi-transmissive concave mirror 606.
Is reflected by the plane mirror 605 and further reflected by the semi-transmissive concave mirror 606 to enter the combiner 602 and reach the eyes 607 of the driver via the combiner 602. The driver's eyes 607 can see and see the display information 608 in front of the windshield 601.

The vehicle display device shown in FIG. 7 has an optical system including a combiner 702 mounted on a windshield 701, a display information display body 704, a concave mirror 705, and a transflective plane mirror 706 disposed in a dashboard 703. (Projector). Display information display 70
4 is transmitted through the semi-transmissive plane mirror 706, reflected by the concave mirror 705, and further transmitted through the semi-transmissive plane mirror 70.
The light is reflected by 6, enters the combiner 702, and reaches the driver's eyes 707 via the combiner 702. Driver's eyes 7
07, the display information 70 is displayed in front of the windshield 701.
8 appears.

[0005]

However, according to the above-mentioned conventional display device, the installation space of the optical system is reduced to about half as compared with the case of using an optical lens, and the device can be made more compact. However, there is a problem that the efficiency of using display luminance is poor. For example, when using a semi-transmissive member having a ratio of the transmitted light amount to the reflected light amount of 50:50, assuming that the luminance of the light source (display information display) is 100, it becomes 50 when transmitted through the semi-transmissive member. Even if the reflectance of the reflective member is 100%, the luminance after reflection by the semi-transmissive member again becomes 25. That is,
Even when a member having the most ideal optical characteristics is used, there is a problem that the utilization efficiency of a single projector (optical system) does not become 25% or more.

[0006] Further, since the use efficiency of display luminance is low, it is necessary to use a high-luminance light source in order to make the luminance of display light reaching the driver's eyes appropriate luminance. Also, there is a problem that the life of the light source is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above, and a display which can use a low-luminance light source by improving the utilization efficiency of display luminance, can reduce the cost of the light source, and improve the life of the light source. It is intended to provide a device.

[0008]

In order to achieve the above object, the present invention provides a display information output means for outputting display information as display light having a peak at a predetermined wavelength, and a display output from the display information output means. It is disposed on the optical axis of the light, and the reflection member that anti shines display light, disposed on the optical axis between the display information output means and the reflection portion <br/> member, the display information output means while transmitting the display light output from the anti by reflections member
The morphism been displayed light diffracted reflected, and whether the display information output means
Angle of incidence of display light output from
And a display diffracted by the transflective member arranged so that the incident angle of the displayed display light is different from the transflective member.
Reflects the light in the direction of the driver and sets the driver in the foreground of the vehicle.
It includes a semi-transmissive member that transmits a direction, a display information output Hand
An object of the present invention is to provide a display device in which a step, a reflection member, and a transflective member are arranged in an instrument .

It is to be noted that the incident angle of the display light is set so that the transmission optical characteristic due to the incident angle of the transmitted display light and the transmission optical characteristic due to the incident angle of the diffracted display light do not become large. desirable.

[0010]

[Function] The incident angle of the display light transmitted through the transflective member,
Semitransparent diffractive element the incident angle is differently reflection member of the display light is diffracted installed by a transmittance peak of the display light transmitted through the semitransparent diffractive element, display light is diffracted by the semitransparent diffractive member Is shifted from the center wavelength of the diffraction efficiency to improve the transmittance and the diffraction efficiency of the display light.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the display device according to the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a configuration of a display device according to the present embodiment, and a windshield 101 of a vehicle is shown.
, A display information display body 104 disposed in a dashboard 103, and a concave mirror 1
05, and reflection type hologram (semi-transmissive diffraction member) 10
6 comprising an optical system. The concave mirror 105
The optical axis is inclined with respect to the incident light by θ / 2 [°]. The concave mirror 105 uses an Al surface evaporation mirror.

The operation of the above configuration will be described. The display light emitted from the display information display 104 passes through the reflection hologram 106 and enters the concave mirror 105.
Here, the optical axis of the concave mirror 105 is θ / 2 with respect to the incident light.
The light reflected by the concave mirror 105 returns to the reflection type hologram 106 at an opening angle θ because the light is reflected at an angle of [°]. This light is diffracted by the reflection hologram 106, enters the combiner 102, and reaches the driver's eye 107 via the combiner 102. The driver's eyes 107 can see and display the display information 108 in front of the windshield 101.

In this device, the display information display 104
Assuming that the luminance of the light source (not shown) is 100, it becomes about 90 when transmitted through the reflection hologram 106, and suppose that the reflectance of the concave mirror 105 as a reflecting member is 100%.
Further, assuming that the diffraction efficiency of the reflection hologram 106 is 90%, the luminance after diffraction by the reflection hologram 106 is 8%.
It becomes 1. That is, when an optical system is configured using members having the most ideal optical characteristics, the utilization efficiency as a single projector can reach about 80%.

Next, the operation of the present embodiment will be described in more detail by showing the configuration of the display information display body 104 and the optical characteristics of the reflection hologram 106. Display information display 10
4 comprises a light source such as a hot-cathode tube having a narrow half-width of the emission energy spectrum of 5 to 10 nm, and a transmissive liquid crystal panel. FIG. 2 shows the wavelength spectrum of the display element light source. The characteristic indicated by the solid line 201 is a wavelength spectrum of a hot cathode tube having a narrow half width at a center wavelength of 543 nm and a half width of about 6 nm. The characteristic shown by the broken line 202 is a center wavelength of 543 nm and a half-value width of about 11 nm in the wavelength spectrum of the high-luminance arc tube (this high-luminance arc tube is being developed by Sony Corporation, Futaba Electronics Corporation). For example, Futaba Electronics Industries, as a "high-brightness backlight for in-vehicle use", has been published on the Institute of Electronics, Information and Communication Engineers, EID 90-89, pp. 19-24.
The details are described here, so the explanation is omitted here).

The characteristics of the reflection hologram 106 are, for example, wavelength characteristics of transmittance as shown by a broken line 301 and a solid line 302 in FIG. 3 in accordance with the emission spectrum of the light source. If the absorption by the glass and the hologram is neglected, the diffraction efficiency will be a value obtained by subtracting each numerical value from 100, and the characteristic will be almost the same as the graph upside down. In practice, the hologram has an incident angle θ / 2 (for example,
At 30 °), a characteristic is provided to match the spectrum of the central wavelength (543 nm) of the light source. As the hologram material, dichromated gelatin, photopolymer and the like are suitable. For example, when an Omnidex film manufactured by DuPont is used, the film thickness is 25 μm, the average refractive index n = 1.5. By setting the refractive index change Δn to 0.03, a reflection hologram having the characteristics shown in FIG. 3 can be created.

FIG. 4 shows an example of an optical system for producing a hologram. Reflection type hologram, incident angle φ / 2 = 30 °
(A reflection-type hologram created such that the incident angle and the reflection angle are the same like a mirror), the interference fringes in the hologram are parallel to the film surface. When this hologram was set at an incident angle of 41 ° and the transmission wavelength characteristic was measured, as shown by a solid line 302 in FIG.
Since the center wavelength of the diffraction efficiency shifts to the shorter wavelength side of 25 nm, it can be seen that the characteristics hardly overlap.

As can be seen from the graph of FIG. 3, in FIG.
When the optical axis is transmitted through the reflection hologram 106, it enters at an incident angle of 41 °, so that the transmittance peak of the reflection hologram 106 becomes 518 nm. However, as described above, the wavelength spectrum peak of the light source is 54
Since it is 3 nm, the actual transmittance is 90% or more.
After reflection by the concave mirror 105, the reflection type hologram 1
Since the light diffracted at 06 enters the reflection hologram 106 at an incident angle of 30 °, the diffraction efficiency (use efficiency) is 90%.
As described above, it is apparent that the efficiency is extremely improved when viewed as a whole of the projector.

A center wavelength is 543 nm, and an incident angle is 30 °.
In the case of the reflection-type volume hologram described above, the generally well-known Coupled Wave thekogel
Calculating using ory, the lattice spacing due to interference fringes in the hologram is about 190.6 nm. Optical axis opening angle θ
Is determined in consideration of the width of the wavelength spectrum of the light source.
In order to shift by nm, the incident angle must be 37 ° (that is, θ = 7).
°). Similarly, to shift by 25 nm, the incident angle may be 41 ° (that is, θ = 11 °). When the wavelength is shifted, the same effect can be obtained even if the wavelength is shifted to the longer wavelength side. For example, in order to shift from 543 nm to the longer wavelength side by 15 nm, the incident angle is 21.8 ° (that is, θ =
8.2 °). Similarly, to shift by 25 nm, the incident angle must be 14.2 ° (that is, θ = 15.8 °).
It is good.

It should be noted that which of these angles is to be selected may be determined in consideration of the actual on-board layout and the efficiency improvement.

FIG. 5 shows the configuration of another embodiment. In this embodiment, the display is not a windshield but a normal meter and is installed in an installation panel. Reference numeral 501 denotes a steering wheel. Also, the same reference numerals as those in FIG.

In the above embodiments, the concave mirror 10
5 has been described as a normal Al surface deposited mirror,
This mirror may be replaced with a hologram. As a generally known method of giving the hologram a concave mirror effect, a mirror behind the hologram dry plate shown in FIG. 4 is removed, and a beam from the same laser is split into two by a half mirror, and the hologram dry plate is removed. It is incident from both sides and interferes. At this time, if one or both beams are divergent light, the hologram can have a concave mirror effect. Further, a similar effect can be obtained even if the reflection type hologram 106 has a concave mirror effect by using an Al plane mirror instead of the concave mirror 105.

[0022]

[Effect] As described above, according to the present invention, the incident angle of the display light transmitted through the semitransparent diffractive element, such that the incident angle of the display light is diffracted by the semitransparent diffractive member are different reflection
For installing the parts material can be provided by improving the utilization efficiency of the display brightness, the display device and enabling the low-intensity light source, capable of improving the cost and light lifetime of the light source.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a display device of the present embodiment.

FIG. 2 is a wavelength spectrum of a display element light source of a display information display.

FIG. 3 is an explanatory diagram showing optical characteristics of a reflection hologram.

FIG. 4 is an explanatory diagram showing an example of an optical system for creating a hologram.

FIG. 5 is a configuration diagram of a display device according to another embodiment.

FIG. 6 is an explanatory view showing an example of a conventional vehicle display device.

FIG. 7 is an explanatory diagram showing an example of a conventional vehicle display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Windshield 102 Combiner 103 Dashboard 104 Display information display body 105 Concave mirror 106 Reflection hologram

Claims (2)

(57) [Claims] And 1. A display information output means for outputting the display information as a display light having a peak at a predetermined wavelength, is disposed on the optical axis of the output display light from the display information output means, that the anti-shine display light a reflection member, together with the display disposed on the optical axis between the information output means and the reflection portion <br/> material, transmits the display light output from the display information output means, reflection member By anti
The morphism been displayed light diffracted reflected, and whether the display information output means
Angle of incidence of display light output from
And a display diffracted by the transflective member arranged so that the incident angle of the displayed display light is different from the transflective member.
Reflects the light in the direction of the driver and sets the driver in the foreground of the vehicle.
It includes a semi-transmissive member that transmits a direction, a display information output Hand
Place steps, reflective members and transflective members in the instrument
Vehicle display device characterized by that. 2. An incident angle of the display light is set so that the transmission optical characteristic by the incident angle of the transmitted display light and the transmission optical characteristic by the incident angle of the diffracted display light do not become large. The display device according to claim 1, wherein: