JPH05131866A - Head up display for vehicle - Google Patents

Abstract

PURPOSE:To improve the transmittance of a liquid crystal so as to obtain high luminance by providing a combiner glass opposedly on the front face side of a display in such a way that the incident light from the display is reflected at a Brewster's angle. CONSTITUTION:A combiner glass 16 is opposedly provided being inclined in such a direction that the optical axis 17 of linearly polarized light coming in after passing the ON-region of a liquid crystal display 10 is injected as S- polarized light (polarized light vertical to the glass surface) to the combiner glass 16 and that the angle of incidence is to be a Brewster's angle thetaB of P- polarized light (polarized light parallel to the glass surface, 56.5 deg. in the case of glass). The P-polarized light from the liquid crystal display 10 is thereby transmitted, and the S-polarized light is reflected, which results in providing the combiner glass 16 with polarizing function. In the case of a graphic pattern or characters being displayed on the liquid crystal display 10, the graphic pattern or characters are displayed being overlapped with the background transmitted into the combiner glass 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle head-up display, for example, which irradiates a windshield of an automobile with display light to display necessary data such as a graphic pattern and characters on the windshield.

[0002]

2. Description of the Related Art Conventionally, there is a structure shown in FIG. 3 as a vehicle head-up display.

That is, the light emitted from the segment type fluorescent display tube 1 is reflected by the reflection mirror 2 and further reflected by the front glass 4 of the vehicle constituted by the combiner glass through the protective glass 3 to be displayed on the driver. It is a structure that is designed to do.

Since the above-mentioned fluorescent display tube 1 is a segment type and the display character shape is limited, a dot matrix type display is desired, but in the case of this dot matrix type, a display is made in comparison with the segment type. Since the emission brightness of the surface is as small as about 1/4, it is difficult to put it into practical use.

Therefore, it is conceivable to form a display by combining a transmissive liquid crystal and a backlight. But,
Since polarizing plates are provided on the front and rear surfaces of the liquid crystal, the light transmittance is reduced by these two polarizing plates, so it is necessary to use a high-intensity backlight, for example, a halogen lamp, as the backlight. However, this halogen lamp generates a lot of heat and has a short life, which makes it unsuitable for vehicles.

[0006]

Therefore, the present invention utilizes the polarization characteristics of the reflectivity of the combiner glass to impart a polarizing plate function to the combiner glass, thereby improving the transmittance of the liquid crystal and increasing the brightness. It is an object of the present invention to provide a vehicle head-up display that can obtain the above.

[0007]

SUMMARY OF THE INVENTION The present invention is a vehicle head-up display in which a light source is arranged on the back surface of a liquid crystal display provided with a polarizing plate, and the incident light from the display is provided on the front side of the display. The head-up display for a vehicle is provided with a combiner glass facing the Brewster's angle.

[0008]

According to the present invention, the combiner glass displays the incident light from the liquid crystal display by transmitting the P polarized light and reflecting only the S polarized light.

[0009]

As a result of the above, according to the present invention, since the combiner glass substitutes for the polarizing plate on the liquid crystal display side, the transmittance of the liquid crystal can be improved and the conventional backlight composed of a fluorescent tube can be used. High-luminance surface emission can be obtained, and a high-luminance head-up display can be obtained even if a dot matrix type display is configured.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings.

The drawing shows a head-up display for a vehicle. In FIG. 1, a liquid crystal display 10 is a holder 1.
1, and a fluorescent tube 12 as a light source on the back side thereof.
Are arranged and surrounded by the reflection plate 13. In addition, a protective glass 14 is arranged on the outgoing light side of the liquid crystal display 10,
The whole is surrounded by a case 15. Protective glass 1 mentioned above
A combiner glass 16 is arranged on the side of the outgoing light of 4,
This combiner glass 16 is the O of the liquid crystal display 10.
The optical axis 17 of the linearly polarized light passing through the N region is incident on the combiner glass 16 as S-polarized light (polarized light perpendicular to the glass surface), and the incident angle is P-polarized light (polarized light parallel to the glass surface). , Glass is approximately 56.5 degrees), and is installed so as to be inclined so as to have a Brewster's angle θB.

When the combiner glass 16 is provided as a pair as described above, the P polarized light from the liquid crystal display 10 is transmitted,
Since the S-polarized light is reflected, the combiner glass 16 has a polarizing function. FIG. 2 shows the liquid crystal display 10 described above, which is a liquid crystal 2 composed of a negative type TN type liquid crystal.
The glass substrates 18 and 18 are provided on both upper and lower surfaces of the display device 0, and the polarizing plate 19 is provided only on the back surface side.

When a graphic pattern or characters are displayed on the liquid crystal display 10 of the vehicle head-up display thus constructed, the P polarized light from the liquid crystal display 10 is transmitted through the combiner glass 16 and only the S polarized light is transmitted to the combiner glass 16. The light is reflected and polarized, and the graphic pattern or the character is displayed overlapping with the background transmitted through the combiner glass 16.

In the above display, combiner glass 1
When the contrast of ON and OFF of the liquid crystal display 10 was measured by darkening the background of 6 (background brightness 10 nit or less), a contrast ratio of about 20 was obtained, and a value equivalent to the contrast ratio of a normal transmissive liquid crystal was obtained. Was obtained. In addition, when the brightness displayed on the combiner glass 16 is measured, a brightness of about 1000 nit is obtained. For example, using a normal liquid crystal display (using two polarizing plates on both sides) having a polarizing plate on the outgoing light side. It was possible to obtain a brightness that was about 1.8 times as high as the display brightness when projected on a combiner glass.

As a result of the above, according to the above-described embodiment, the combiner glass 16 substitutes for one polarizing plate on the liquid crystal display side used for two sheets, so that the transmittance of the liquid crystal 20 can be improved and the conventional fluorescent light can be used. Even if a backlight composed of the tube 12 is used, high-luminance surface emission can be obtained. Even if a dot matrix type display is constructed, a high-luminance head-up display can be obtained.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram of a vehicle head-up display.

FIG. 2 is a sectional view of a liquid crystal display.

FIG. 3 is a cross-sectional configuration diagram of a conventional vehicle head-up display.

[Explanation of symbols]

 10 ... Liquid crystal display 12 ... Fluorescent tube 16 ... Combiner glass 19 ... Polarizing plate 20 ... Liquid crystal

Claims (1)

[Claims] 1. A vehicle head-up display in which a light source is arranged on the back surface of a liquid crystal display having a polarizing plate, and the angle of light incident from the display is reflected on the front side of the display at a Brewster's angle. Head-up display for vehicles that has a combiner glass as opposed to it.