JPS6145218A - Display device for vehicle - Google Patents

Abstract

PURPOSE:To improve visibility and display quality by polarizing linearly drive information display light incident upon a windshield so that the electric field direction of polarization goes to parallel to the incidence surface, and setting the angle of incidence of the display light to the windshield to a Brewster angle. CONSTITUTION:A projector 5 which displays a drive information image is incorporated in an instrument panel 6 and consists of a fluorescent display tube 5a as an image display body, color filter 5b, lens 5c, and polarizing plate 5d, which polarizes light passed through the lens 5c in the direction of an electric field vector. When the projector 5 is positioned opposite the windshield 1 so that the image display light from the projector 5 is incident on the internal surface of the windshield 1 at the Brewster angle alphaB, there is no reflection on the internal surface of the windshield 1. Then, the image display light traveling inward is reflected by the surface of a wavelength selective reflecting film including a vapor-deposited film 4 and a virtual image formed outside and in front of it is viewed, thereby improving the visibility and display quality.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a display device for a vehicle that improves the visibility of a display by eliminating reflections on the inner surface of a windshield.

(b) Prior art In the past, driving information such as vehicle speed, mileage, remaining fuel level, time, and various warnings was displayed using meters, clocks, or warning lamps installed on the instrument panel. It has been proposed to display this driving information in front of the windshield so that you do not have to take your eyes away from the front view to view this driving information inside the vehicle (Japanese Unexamined Patent Publication No. 182541/1982).

This type of display device is called a head-up display device, and a projector containing a liquid crystal display panel is installed on the instrument pad inside the windshield, and the driving information image displayed on the liquid crystal display panel is reflected directly or using a reflector. The image is guided to a board or display device, or the image is formed in front of the outside of the windshield. In this device, a reflector for wavelength selection is attached to the inside surface of the windshield, and a non-reflective coating is applied to prevent light from reflecting. It is being considered to embed it inside the windshield because it can cause damage. This will eliminate the problem of damage, but the inside of the windshield may
& Because the layered structure creates multiple surfaces, the driving information display image from the projector is reflected on each of these surfaces, resulting in a double display image.

311, and visibility is significantly reduced.

(c) Purpose and structure of the invention The present invention has been made in view of the above points, and an object of the present invention is to improve the visibility of display by eliminating reflection on the inner surface of the windshield. , the driving information display light incident on the windshield is linearly polarized so that the electric field direction of the polarized light is parallel to the windshield entrance surface,
In addition, the angle of incidence of the driving information display light on the windshield is set to be the Prewster angle.

(d) Examples The present invention will be explained below based on the drawings.

Prior to explaining the embodiments, the principle of the present invention will be explained using FIG. 2.

As shown in Figure 2, when the refractive index ring and the medium n are in contact, linearly polarized light (rl) perpendicular to the plane of incidence of the incident light
Let the reflection coefficient of linearly polarized light (r,) parallel to r, , respectively be
When expressed as r, tan (α1-α□) sln (α1-α wealth) fit s l na, mfi, s i na.

Here, α is the angle of incidence, and α1 is the angle of refraction. (As is known, when the angle of incidence α satisfies the following equation, r becomes zero, and α−αI in this case is known as the Priest angle.

For example, since the refractive index of glass is 1.5, the Prustian angle when incident from air to glass is 56.3'', and R is the boundary surface.

The present invention aims to prevent double or triple display of driving information by focusing on this Prewster angle, and one embodiment is shown in FIG. 1.

In FIG. 1, inside a windshield 1, a polyvinyl butyral 2, a polyester sheet 3, and a 5if
Iris 1gI consisting of three layers of t, TlOs, 310 proverbs
4 are laminated to form a wavelength selective reflection sheet.

On the other hand, a projector 5 for displaying the driving information image. is incorporated into the instrument panel 6, and is composed of a fluorescent display tube 5a as an image display, a color filter 5b, a lens 5G, and a polarizing plate 5d. deflects parallel to (direction of electric field vector).

What is important here is that the image display light emitted from the projector 5 is on the windshield! The projection n5 is arranged with respect to the windshield l so that it is incident on the inner surface of the windshield 1 at a breaster angle α, and in this way, the reflection of the image display light on the inner surface of the windshield 1 is reduced. Becomes zero. The image display light that has advanced into the inside of the windshield 1 is reflected by the surface of the wavelength selective reflection film containing the vapor 1!11114, and a virtual image thereof is formed on the outside front of the windshield 1. The driver will see this virtual image with eyes E. Although there may be some reflection of the image display light on the outer surface of the windshield l, it can be ignored because it is one order of magnitude smaller than the amount of light reflected by the wavelength-selective reflective film. If you want to reduce the reflection on the outer surface of the windshield 1, you can add a light absorber to the commonly used polyvinyl butyral or glass, or you can use colored glass, which is already used in some car models. Good,
In the figure, 7 is a driving information image formed on the front outside of the windshield 1, and 8 is a foreground visible in front of the vehicle.

In the above embodiment, the electric field vector component of the light is polarized by the polarizing plate, but the component perpendicular to this can be considered in the same way. In addition, a liquid crystal panel can be used as a display body for driving information images, and if this liquid crystal panel is originally equipped with a polarizing plate, it is possible to use the polarizing plate so that the direction of polarized light is parallel to the plane of the paper. This can be realized without using a separate polarizing plate.

(e) Detailed Description of the Invention As described above, the present invention provides a display device such as a head-up display used in a vehicle having a light wavelength selective film inside the windshield, in which driving information display light incident on the windshield is polarized. Since the electric field direction is parallel to the plane of incidence, the display light is a-tightly polarized, and the angle of incidence of the display light on the windshield is set to the Priest angle, so the driving information display light is reflected on the inner surface of the windshield and is reflected on the windshield. Overlapping with the reflection from the internal optical wavelength selection film, the operation 1 signal image becomes 211. 311, and visibility and display quality are improved. In addition, there is no need to apply a 'M coating such as an anti-reflection coating to the inner surface of the windshield.
No damage caused by wiping or film peeling.

Furthermore, since reflection loss on the inner surface of the windshield is reduced, the amount of light reflected by the wavelength selection film, which contributes to the original display, is increased, improving visibility.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of an embodiment of a vehicle display device according to the present invention, and FIG. 2 shows a Priest angle used in the present invention of 1! FIG. 〆、・ 1... Windshield, 2... Polyvinyl Petitler 1' Ru, 3... Polyester sheet, 4... Clan film, 5
... Projector, 6... Instrument panel, 7.
... Formed driving information image, 8... Foreground.

Claims (1)

[Claims] In a vehicle display device that reflects driving information displayed on a display section provided inside the windshield by a light wavelength selective film provided inside the windshield and forms an image on the outside front of the windshield and displays the image, A polarizing means is provided for linearly polarizing the incident driving information display light so that the direction of the electric field of the polarized light is parallel to the windshield incident surface, and the angle of incidence of the display light on the windshield is set to the Priest angle. Vehicle display device.