JPH01302383A - On vehicle liquid crystal display - Google Patents

Abstract

PURPOSE:To prevent the reflected image of a display surface projected in a front glass by setting the polarizing direction of a light emitted from a projecting part so as to be parallel to an incident surface in the front glass of a light beam to be emitted from the display surface and made incident on the position of the mean sight line of a driver. CONSTITUTION:For the reflection of the light on the boundary surface of a medium different in refraction factor, there are (s) components vertical to the incident surface to contain an incident light B and a reflected light C and (p) components parallel to the incident surface. Since the components to be reflected by a front glass 4 and to reach eyes of the (p) components and (s) components of the light B to be emitted from a display surface 6 of a projecting part 51 of a liquid crystal display 5 and made incident on the front glass 4 are mainly the (s) components, a means to eliminate the (s) components of the light B incident on the front glass 4 is executed. Namely, a combination is executed by setting the polarizing direction of the light emitted from the display surface 6 so as to be made parallel to the incident surface in the front glass 4 of the light beam incident on the position of the mean sight line of the driver. Thus, the project-in of a video to the front glass made into the hinderence of a driving can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a vehicle-mounted liquid crystal display device that prevents images of its display surface from being reflected on a windshield.

(Prior Art) An in-vehicle liquid crystal display device 5 is placed near various indicators 7 in front of the driver's seat, as shown in FIGS. 9 and 10, for example. Road map display.

It is used for multiple purposes, such as monitoring the remaining amount of fuel, and as a receiver for TV broadcasting. However, depending on where it is placed, as shown in FIG. 11, in addition to direct light A from the display surface 6 of the projection section 51 of the display device 5, light B incident on the windshield 4 may be reflected. Sometimes you can see C. FIG. 11 shows how the image on the display surface 6 of the projection section 51 of the liquid crystal display device 5 is reflected on the upper part of the windshield 4. Also, the darker the field of view, the more clearly the reflected image will be recognized. The image reflected on the windshield 4 obstructs the driver's view.

It is a danger. As a means to prevent such reflection on the windshield, conventionally, as shown in the cross-sectional structure of FIG. The arranged film 8 was put into practical use.

As shown in FIG. 13, the film 8 has a structure in which light incident beyond a specific angle is absorbed by the black strip 82, so that the light reaches only the range S1 and does not reach the range S2. It becomes. By placing this in front of the display surface 6 of the projection section 51 of the display device 5, the light does not reach the windshield 4 as shown in FIG. 14, and the light is directed only toward the driver. By reaching.

It is possible to prevent images from being reflected on the windshield 4. However, since the film 8 has a structure in which a large number of fine lines are lined up in the horizontal direction as shown in FIG. 15, moiré occurs due to interference with the pixel arrangement pattern of the display surface 6 of the projection section 51. was there. Furthermore, since the fine lines are not necessarily uniform, there is also the disadvantage that streaks become noticeable and interfere with direct viewing of the image.

(Problems to be Solved by the Invention) As mentioned above, a film in which many fine black strips are arranged in parallel, which was used to prevent the image on the display screen from being reflected on the windshield, has been developed. The in-vehicle display device used has two problems: ■ Moiré occurs due to interference with the pixel arrangement pattern on the display surface of the projection section; ■ Uneven streaks are noticeable due to unevenness of the strips, which hinders direct viewing of images. Also, the range in which the light emitted from the display surface spreads is limited primarily to the driver's direction, resulting in the inconvenience that the image cannot be clearly seen by anyone other than the driver.

The present invention has been made in order to improve the above-mentioned drawbacks of the conventional device, and an object of the present invention is to provide an in-vehicle liquid crystal display device that prevents images from being reflected on the windshield, which would impede driving.

[Structure of the invention]

(Means for Solving the Problem) The present invention has been made to achieve this object, and the present invention has been made in order to achieve the above object.

It is characterized in that the light rays exiting from the display surface and entering the position of the driver's average line of sight are set parallel to the incident surface of the windshield and combined.

A liquid crystal display device according to the present invention will be described below.

The relationship between the incident light B incident on the windshield 4 and its reflected light C shown in FIG. 11 and its reflection on the surface of the windshield 4 is shown in FIG. 6, when a light ray enters the glass surface from the air. When light is reflected at the boundary surface of a medium with a difference in refractive index, an electric vector component (hereinafter S The reflectances of the electric vector component parallel to the plane of incidence (hereinafter referred to as the p component) can be described by Fresnel's reflection law, as is well known. For example, when the refractive index of the windshield 4 is assumed to be 1.5, how these reflectances change with respect to the incident angle θ is as shown in FIG. The reflectance of the S component is higher than that of the P component regardless of the angle of incidence (it is equal only when it is incident perpendicularly). It can be considered that the light C reflected by the windshield 4 mainly consists of the S component, when the angle of incidence θ satisfies tanθ=n, where the refractive index of the windshield 4 is n, that is, the angle of incidence θ matches the polarization angle. As mentioned above, sometimes there is only the S component.

Among the p component and S component of the light B that exits from the display surface 6 of the projection section 51 of the liquid crystal display device 5 and enters the windshield 4, it is mainly the S component that is reflected by the windshield 4 and reaches the eyes. Therefore, if a means is taken to eliminate the S component of the light B incident on the windshield 4, that is, the component perpendicular to the plane of incidence on the windshield, the reflected light C can be reduced.
The intensity of can be reduced to zero or reduced.

(Function) The polarization direction of the light emitted from the display surface of the projection part of the in-vehicle liquid crystal display is set to be parallel to the plane of incidence on the windshield of the light rays emitted from one display surface and incident on the driver's average line of sight. By combining (υ) it is possible to prevent the reflected image of the display surface of the projection section from being reflected on the windshield.

(2) Since there is no fine black band like the film 8, no moiré occurs due to interference with the pixel arrangement button on the display surface of the projection section.

(2) Unlike the film 8, the direction of polarization of the light emitted from the projection section is not limited to the direction of the driver, so that people other than the driver can view the screen without any trouble. There are effects such as

(Examples) Example 1 The configuration of an on-vehicle liquid crystal display device according to an example of the present invention is shown in FIG. The liquid crystal cell 2 of the projection section 11 of the display device 1 is of a so-called GH mode, and has a configuration in which a polarizer 3 is disposed on the back side thereof. The direction angle α of polarization of the light emitted from the display surface 111 is shown in FIG. 2(a).
As shown in FIG. As shown in FIG. 2, the display surface 111 is rotated by an angle of 20 degrees with respect to the vertical direction 1-1'. At angles other than the set angle of 20'', the image on the display surface 111 was clearly recognized as a reflected image, whereas in the state where the angle was set in this way, it was not recognized at all.

Further, as shown in FIGS. 4(a) and 4(b), the display surface 111 of the projection unit 11 of the display device 1 is placed at a position where the reflected image can be seen almost directly above and to the side of the windshield 4. In , the set angles were approximately 0' and approximately 90'', respectively.

In any of these cases, almost no reflected image of the image on the display surface 111 was observed.

Embodiment 2 The configuration of a vehicle-mounted liquid crystal display device according to another embodiment of the present invention is shown in FIG.
The liquid crystal cell 2 of 1 is of a so-called TN mode,
Polarizers 31 and 32 are arranged on both sides in an angular relationship such that the directions of polarization are perpendicular to each other6.
The polarization direction of the polarizer 32 is set so that the direction angle α of the polarization of the light emitted from the display surface 111 is 20'' as in the first embodiment, and the polarization direction of the polarizer 31 and the liquid crystal are set so as to correspond to that direction. The orientation of the liquid crystal of the cell 2 is set.The surface of the polarizer 32 on the m-side is subjected to a matte treatment with fine irregularities. This was carried out to prevent the image from being reflected as an image.The matte was lightly processed so as not to impair the resolution of the image on the display surface 111.The same experiment as in Example 1 was conducted using this display device 1. When this was carried out, although a reflected image was slightly visible due to the polarization performance being slightly reduced by the matte treatment, the effects aimed at by the present invention were sufficiently compared.

The present invention is not limited to the above embodiments, and can be implemented with various modifications without departing from the gist thereof. In Example 2 above, an example was described in which the surface of the polarizer 32 was matte-treated to prevent surrounding objects from being reflected on the polarizer 32. good.

Further, an antireflection film that utilizes light interference may be provided.

〔Effect of the invention〕

According to the present invention, the direction of polarization of the light emitted from the display surface of the projection section is set parallel to the plane of incidence on the windshield of the light rays that exit from the display surface and enter the position of the driver's average line of sight. Because there is.

■ It is possible to prevent the reflected image of the display surface of the projection section from being reflected on the windshield.

(2) Since there is no fine black band like the film 8, no moiré occurs due to interference with the pixel arrangement button on the display surface of the projection section.

(2) Unlike the film 8, the direction of polarization of the light emitted from the projection section is not limited to the direction of the driver, so that people other than the driver can view the screen without any trouble. It has the following effects.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of an in-vehicle liquid crystal display device according to an embodiment of the present invention. FIG. 2(a) is a diagram showing how the image on the display screen of the projection section is reflected on the upper part of the windshield. FIG. 2(b) is a diagram illustrating the effect of the in-vehicle liquid crystal display device according to the embodiment of the present invention in eliminating the image reflected on the display surface by the windshield. FIG. 3 is a diagram showing that the direction of polarization of light emitted from the display surface of the vehicle-mounted liquid crystal display device according to the embodiment of the present invention is rotated and set by a specific angle with respect to the vertical direction of the display surface. FIG. 4(a) is a diagram showing how the image on the display screen of the projection section is reflected almost directly above the windshield. FIG. 4(b) is a diagram showing how the image on the display screen of the projection section is reflected almost directly to the side of the windshield. FIG. 5 is a diagram showing the configuration of an in-vehicle liquid crystal display device according to another embodiment. FIG. 6 is a diagram showing how light rays are incident and reflected on the windshield surface. FIG. 7 is a diagram showing changes in reflectance with respect to the incident angle on a glass surface with a refractive index of 1.5, divided into a component parallel to the incident surface (p component) and a component perpendicular to the incident surface (S component). FIG. 8 is a diagram showing how light emitted from the display surface of the projection section of the display device is reflected by the windshield and enters the eyes. FIG. 9 and FIG. 10 are diagrams showing typical positions where an in-vehicle display device is arranged. FIG. 11 is a diagram showing light rays that come out from the display surface of the projection section of the in-vehicle display device and directly reach the driver's eyes, and light rays that are reflected on the windshield and reach the driver's eyes. FIG. 12 is a diagram showing the structure of a film used in conventional vehicle-mounted display devices to prevent images on the display screen from being reflected on the windshield. FIGS. 13 and 14 are diagrams explaining the effects of the film whose structure is shown in FIG. 12. FIG. 15 is a diagram showing how fine strips are visible when the film whose structure is shown in FIG. 12 is viewed from the front. 1... Liquid crystal display device t 11... Projection section of the liquid crystal display device. 111...Display surface of the projection section. 2...Liquid crystal cell, 3,31.32...Polarizer. 4... Windshield, 5... Display device. 51... Projection section, 6... Display surface of the projection section. 7...Indicator. 8... Agent for anti-reflection film Patent attorney Nori Ken Yudo Chika Mitsuyuki Matsuyama Figure 5 Figure 6 included @$ + Figure 7 Figure 8 Figure 9 to Figure 1O Figure 11 Figure β Figure 12 - Figure 14 Figure 15

Claims (1)

[Claims] 1) The direction of polarization of the light emitted from the display surface of the liquid crystal display device is parallel to the plane of incidence on the windshield of the light rays that exit from the display surface and enter the position of the average line of sight of the driver. An in-vehicle liquid crystal display device characterized in that it is configured and combined with. 2) The vehicle-mounted liquid crystal display device according to claim 1, further comprising a light diffusing means on the display surface. 3) The vehicle-mounted liquid crystal display device according to claim 1, further comprising a light reflection prevention means on the display surface. 4) The in-vehicle liquid crystal display device according to claim 1, wherein the linear polarization means combined on the display side has a variable polarization direction.