JPH08327939A - Head up display - Google Patents

Abstract

(57) [Abstract] [Purpose] To reduce the chromatic aberration while improving the visibility of the display virtual image that is comparable to the brightness of the background. [Structure] A hologram 1 arranged inside the vehicle with respect to a dark color concealing layer 3 provided on a peripheral portion of a windshield 10, and a light source 16 comprising a cold cathode tube or a hot cathode tube provided below the windshield 10. A head-up display in which light emitted from the light source 16 and transmitted through the display body 4 is incident, is diffracted toward the observation position 6 of the observer, and the observer visually recognizes the display virtual image 7.

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, and more particularly to a head-up display which is equipped with a reflection hologram on a windshield of a vehicle such as a vehicle or an aircraft so as to project information necessary for a driver such as speed. Regarding display.

[0002]

2. Description of the Related Art A head-up display (hereinafter referred to as HUD) is used as a method of displaying information to a driver in a vehicle.
Has been used recently. This is because the optical information projected from the light emitting display means such as a liquid crystal display device is displayed on a combiner including a half mirror and a hologram provided on the windshield so that the driver hardly moves his line of sight from the driving state. The information can be read.

In particular, a hologram using a hologram as a combiner is capable of diffracting optical information toward a driver and forming an image at an arbitrary position, and it has a high brightness without impairing the foreground brightness. It is effective as a combiner for HUD because it has a characteristic that a display virtual image can be obtained.

However, when such a hologram is arranged on the transparent portion of the windshield, the front background of the hologram is bright, so that a virtual image displayed unless a light source with a high brightness of the light emitting display means is used. The visibility of the will deteriorate. Therefore, the brightness of the display virtual image is 3000c.
d / m ² or more is required. In order to increase the brightness of the display virtual image, it is required to use a halogen lamp or the like having a high brightness as the light source of the light emitting display means.

On the other hand, when the hologram is arranged on the windshield, if the hologram is a regular reflection type hologram, the observer will see a double image due to the diffracted light by the hologram and the reflected light on the glass plate surface. . for that reason,
It is desirable to use a non-regular reflection type hologram.

However, when a non-regular reflection type hologram is used, the angle of diffraction is different depending on the wavelength of the light from the light emitting display means, so that chromatic aberration occurs in the display virtual image.

[0007]

Therefore, as shown in FIG. 3, the light emitting display means is a light source 8 composed of a halogen lamp,
It has been proposed that the display body 4 is composed of a liquid crystal display element that makes the light from the light source 8 contain information, and the bandpass filter 9 arranged between the light source 8 and the display body 4. By configuring the light emitting display means in this way,
It is possible to narrow the wavelength band of the light including the information that is incident on the hologram 1 and reduce the chromatic aberration due to the hologram. In the figure, 6 is the observation position of the observer, 7
Is a display virtual image, and 10 is a windshield.

However, in the above-mentioned structure of the light emitting display means, the number of parts is increased and the light emitting display means becomes large in size. Also, the bandpass filter itself is expensive. Furthermore, when a bandpass filter having a half width of several nm is used to reduce chromatic aberration, the loss of the light amount from the light source becomes large. Therefore, it is necessary to use a light source with a large power consumption, for example, a power consumption of 50 W or more. As a result, a mechanism for radiating the heat emitted from the light source is required, and the mechanism is also complicated. By using the bandpass filter, the mechanism of the entire light emitting display means is also complicated.

Although it is conceivable to use a light source that originally emits light in a narrow band as a light source, such a light source does not have sufficient brightness, and the displayed virtual image loses the brightness of the background. It had drawbacks.

An object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide a head-up display that has not been known in the past.

[0011]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and emits light including a hologram arranged on a windshield and light provided below the windshield and containing information. In a head-up display that includes at least a display unit and diffracts the light toward an observation position of an observer by a hologram, the windshield has a dark-colored hiding layer at a peripheral portion thereof, and the dark-colored hiding layer is a vehicle. A head-up display is provided, in which a hologram is arranged inside, and the light emitting display means has a light source composed of a cold cathode tube or a hot cathode tube.

[0012]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a schematic sectional view showing an example of a head-up display according to the present invention. A windshield 10 made of laminated glass in which two glass plates 2 and 2 ′ are laminated with an intermediate film 15 interposed between them is provided with a dark color hiding layer 3. The hologram 1 is arranged on the inside of the vehicle with respect to the dark color hiding layer 3 of the windshield 10.

Below the windshield 10, there is provided a light emitting display means 5 having a light source 16 composed of a cold cathode tube or a hot cathode tube and a display body 4 composed of a liquid crystal display element for containing information in the light emitted from the light source 16. It is equipped. Thus, the light including the information emitted from the light emitting display means 5 is the hologram 1
And is diffracted toward the observation position 6 of the observer, and the observer visually recognizes the display virtual image 7.

In this example, the distance between the hologram 1 and the light emitting display means 5 is 200 mm, and the light incident from the light emitting display means 5 at an incident angle of 10 ° is observed by an observer at a diffraction angle of 65 °. Diffract toward position 6 and holograms 1 to 3
A hologram was used such that the display virtual image 7 was observed at a position separated by 00 mm.

The cold cathode tube or the hot cathode tube has a half width of 5n.
It has a light emission characteristic in a narrow band of about m. Therefore, even if a non-regular reflection hologram having chromatic aberration is used, blurring due to the chromatic aberration can be reduced to a negligible level.

The cold-cathode tube or the hot-cathode tube having a narrow band emission characteristic usually has an emission luminance of several hundred cd / m ² or less.
Therefore, when the hologram is arranged on the transparent portion of the windshield, the visibility of the display virtual image is deteriorated due to the brightness of the background. In the HUD of the present invention, since the hologram is arranged in the dark color hiding layer, the HUD has several hundreds cd / cd like a cold cathode tube or a hot cathode tube used for obtaining a narrow band emission characteristic.
Even with a light source having an emission luminance of m ² or less, the visibility is sufficiently high.

As these cold cathode tubes or hot cathode tubes,
A flat type may be used as it is, or a diffuser plate may be used in combination with a tubular cold cathode tube or a hot cathode tube.

FIG. 2 is a graph showing the relationship between the distance between the display virtual image and the hologram and the chromatic aberration when the HUD is constructed using a cold cathode tube or a hot cathode tube as the light source.
As the degree of chromatic aberration, the deviation of the diffraction angle due to the difference in the half width of the light source is expressed in millirad. Further, the relationship between the distance between the display virtual image and the hologram and the chromatic aberration is changed by changing the difference between the incident angle to the hologram and the diffraction angle from the hologram.
Two cases are shown.

As for the chromatic aberration, if it is 1 millirad or less, it is allowed. Therefore, as shown in FIG. 2, when a cold cathode tube or a hot cathode tube is used as a light source, the chromatic aberration is set to 1 millirad or less by setting the difference between the incident angle and the diffraction angle to 70 ° or less. It is possible to obtain a sharp display virtual image.

The information to be displayed in the present invention is appropriately selected according to its display application, and examples thereof include a vehicle speedometer, a tachometer, various warning lamps and navigation information. The observer is mainly a driver of the vehicle, but can also include passengers other than the passenger seat, and all these persons.

The hologram is usually several 10 mm square to several 1
It has an area of about 00 mm square and a thickness of about several tens of μm, and has a light diffraction function. As this hologram, a so-called hologram such as an emboss type or a Lippmann type hologram can be widely used. As the hologram material, various photosensitive materials such as polyvinylcarbazole, dichromated gelatin, photoresist, photopolymer and silver salt can be used.

When such a hologram is mounted on a vehicle, it may be arranged, for example, on the inside surface of the windshield, but in view of protection of the hologram in particular, it is used by being enclosed inside the windshield. preferable. The hologram may have a single-layer configuration or a plurality of layered layers. In addition, the hologram can be provided at an appropriate place by using a transmission hologram. In any case, it is arranged on the inner side of the vehicle with respect to the dark color hiding layer. Further, the diffraction characteristics of the hologram and the optical arrangement associated therewith are also appropriately determined according to the space of the vehicle and the like, and are not limited to the above examples.

The observer is mainly the driver of the vehicle, but can also include passengers such as the passenger seat and all other persons.

The dark color hiding layer can be exemplified by a ceramic paint such as black that is normally burned on the window glass of a vehicle. It is baked when bending the glass plate, but an S dark color film or the like is separately provided in the windshield. It may be enclosed.

[0026]

According to the present invention, since the hologram is arranged in the dark color concealing layer of the windshield, it is not affected by the brightness of the background in the transparent portion of the windshield, and the light emission brightness is used as the light source used in the light emitting display means. Can be used.

In this way, since a light source with low emission brightness can be used, a light source having a narrow band emission characteristic can be used. By using a cold cathode tube or a hot cathode tube as the light source, the chromatic aberration of the display virtual image can be reduced. Can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic sectional view showing an example of a HUD according to the present invention.

FIG. 2 is a graph showing the relationship between the distance between a display virtual image and a hologram and chromatic aberration when a light source according to the present invention is used.

FIG. 3 is a schematic sectional view showing an example of a conventional HUD.

[Explanation of symbols]

 1: Hologram 2, 2 ': Glass plate 3: Dark color concealing layer 4: Display body 5: Light emitting display means 6: Observing position of observer 7: Displayed virtual image 8: Halogen lamp 9: Bandpass filter 10: Windshield 15: Intermediate film 16: Light source

Claims (2)

[Claims] 1. A hologram arranged on a windshield, and at least a light emitting display unit provided below the windshield for generating light containing information, and directing the light to an observation position of an observer by the hologram. In the head-up display that diffracts light, the windshield has a dark-colored hiding layer at the peripheral edge thereof, and a hologram is arranged inside the dark-colored hiding layer, and the light emitting display means is a cold cathode tube or a hot cathode. A head-up display having a light source formed of a tube. 2. The difference between the incident angle of light entering the hologram from the light emitting display means and the diffraction angle of light diffracted from the hologram toward the viewing position of the viewer is 70 ° or less. The head-up display according to claim 1.