JPH05119293A - Display device - Google Patents

Abstract

PURPOSE:To provide a display device where the liquid crystal display panel of a backlight system is used as a display element, the utilization efficiency of a luminous flux is enhanced while preventing the unnecessary occurrence of a multiple reflected image, the brightness of the image of the display information of a display element is made high and excellent observation is accomplished. CONSTITUTION:As to the display device where two pieces of information, that is, the display information from the display element 1 and image information 8 positioned in a direction different from the display information are spatially superposed through a light transmissive luminous flux coupling element 3 and observed in the same visual field, the display element 1 is constituted of the liquid crystal display panel of the backlight system and the liquid crystal display panel is arranged to be inclined so that its normal may form the angle of polarization or an angle near it with an optical axis.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device, and more particularly to an image information such as a natural scene in front of a display device and an artificial image through a light beam coupling element composed of a transparent multi-layered reflective surface and a volume phase diffraction grating. The present invention relates to a display device suitable for simultaneously observing both pieces of display information created by a display element.

[0002]

2. Description of the Related Art Display information from a display device and image information such as natural scenery of the outside world are within the same field of view by using an optically transparent light flux coupling element such as a multilayer reflection surface or a volume phase diffraction grating. The display device that is spatially superposed for observation is
Generally called a head-up display device, it is widely used in each field.

Conventionally, various display devices have been proposed in which this head-up display device is used for various vehicles such as the cockpit of an aircraft.

In this head-up display device,
For example, in the case of an aircraft, in addition to the marks for shooting, display information such as speed, altitude, remaining amount of fuel, etc. is displayed, and the same content is displayed on automobiles, railway vehicles, etc.

As a problem to be solved by the conventional head-up display device, the luminous flux from the display element is multiple-reflected by the luminous flux coupling element, and the display information is observed as double or triplet and the visibility is lowered. There was a problem of making it.

On the other hand, Japanese Patent Application Laid-Open No. 61-45218 proposes a display device having a structure as shown in FIG. 2 to solve this problem.

In the figure, the luminous flux from the fluorescent display tube 21 as a display element is incident on the luminous flux coupling element 25 through the color filter 22, the lens 23, and the polarizing plate 24. Then, it is reflected and deflected toward the observer 26 by the light beam coupling element 25.

On the other hand, the light flux from the image information 28 such as the scenery of the outside world passes through the light flux coupling element 25 and enters the observer 26.

In the figure, an image 27 of the display information of the display element 21 is formed at a predetermined position on the outside through the light beam coupling element 25,
The image information 28 of the outside world is spatially superimposed, and both pieces of information are observed from the same direction.

At this time, the light beam incident on the light beam combining element 25 is polarized by the polarizing plate 24 and its polarization direction is changed.
It is limited so that it becomes parallel (P polarized light) within the plane of incidence on 5,
In addition, the angle α _B formed by the optical axis L of the display unit 20 and the normal line of the light beam coupling element 25 is arranged to be the Brewster angle. The reflectance of P-polarized light at the Brewster angle is zero.
As a result, in this display device, the light flux based on the display information is prevented from being multiple-reflected on the front surface and the back surface of the light flux coupling element 25, the double image and the triple image are prevented from occurring, and the observation is performed in a good state. ing.

[0011]

However, in the display device shown in FIG. 2, of the light flux from the display element 21, only the P-polarized light is passed by the polarizing plate 24 and the other light flux is shielded. For this reason, there is a problem that the utilization efficiency of the light flux is poor, the brightness of the image 27 of the display information of the display element is low, and the visibility is lowered.

The above-mentioned Japanese Patent Laid-Open No. 61-45218 proposes a display device in which a liquid crystal display panel provided with a polarizing plate as a display element is used also as the polarizing plate 24. Has not shown any solution.

In the present invention, a backlight type liquid crystal display panel is used as a display element, and the liquid crystal display panel is arranged at an appropriate angle with respect to the optical axis to prevent the generation of unnecessary multiple reflection images while preventing the occurrence of light flux. An object of the present invention is to provide a display device capable of improving utilization efficiency and brightness of an image of display information on a display element and enabling good observation.

[0014]

SUMMARY OF THE INVENTION A display device of the present invention is a light-transmitting luminous flux for two pieces of information: display information from a display element and image information located in a direction different from the display information. In a display device for spatially overlapping and observing in the same visual field through a coupling element, the display element is composed of a backlight type liquid crystal display panel, and the liquid crystal display panel has its normal line on the optical axis. On the other hand, it is characterized in that it is arranged so as to be inclined at a Brewster's angle or an angle in the vicinity thereof.

In particular, in the present invention, the liquid crystal display panel is arranged so as to be inclined such that the normal line thereof is within the range of 30 to 65 degrees with respect to the optical axis, and the luminous flux emitted from the liquid crystal display panel is The polarized light oscillates in a plane parallel to the incident surface to the light beam coupling element, and the incident angle to the light beam coupling element is set to be Brewster's angle or an angle in the vicinity thereof.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic view of the essential portions of an embodiment of the present invention.

In the figure, reference numeral 2 is a light source means, which is composed of, for example, an incandescent lamp. Reference numeral 1 denotes a display element, which is composed of a backlight type liquid crystal display panel, and a polarizing plate is provided in a part thereof. The liquid crystal display panel 1 is arranged so as to be inclined with respect to the optical axis L of the light source means 2 so that the normal line thereof is the Brewster angle or an angle θ in the vicinity thereof. That is, the liquid crystal display panel 1 is illuminated with the light beam from the light source means 2 from the direction of the angle θ with respect to the normal line.

It is preferable to set each element so that the angle θ falls within the range of 30 ° to 65 ° in view of observation and downsizing of the entire apparatus.

Reference numeral 3 denotes a light flux coupling element, which is composed of, for example, a multi-layer reflection film having a wavelength selectivity or a hologram, and reflects or deflects the light flux from the liquid crystal display panel 1 toward the observer 4 or diffracts it. At this time, the luminous flux from the display information on the liquid crystal display panel 1 forms an image 7 of the display information at a position behind the luminous flux coupling element 3 by the luminous flux coupling element 3. 8
Is image information such as the scenery of the outside world, and the light flux from the image information 8 passes through the light flux coupling element 3 and is incident on the observer 4.

In the display device shown in the figure, the image 7 of the display information on the liquid crystal display panel 1 and the image information 8 such as the scenery behind the light flux coupling element 3 are spatially superimposed via the light flux coupling element 3,
Both pieces of information are observed in the same field of view.

When a half mirror or a hologram having no lens action is used as the light beam coupling element 3 as in this embodiment, a lens system for magnifying and projecting display information is arranged at an arbitrary position in the optical path. It may be configured with.

Next, the traveling state of the luminous flux in this embodiment will be described.

The light flux from the light source means 2 which is incident on the liquid crystal display panel 1 is optically modulated according to the display pattern of the liquid crystal display panel 1 and is emitted as a light flux having a polarization state limited by a polarizing plate provided therein. To do. In the present embodiment, the liquid crystal display panel 1 is arranged so that the emitted light beam at this time becomes a polarized light beam that oscillates in a plane parallel to the incident surface to the light beam combining element 3, that is, P-polarized light (polarized light that oscillates parallel to the paper surface). The polarization direction of the polarizing plate provided inside is set.

In this way, the light beam emitted from the liquid crystal display panel 1 as P-polarized light is made incident on the light beam combining element 3 and is reflected and deflected or diffracted by the light beam combining element 3 to be guided to the observer 4. . At this time, the incident angle θ _B of the light flux from the liquid crystal display panel 1 on the light flux coupling element 3 is set to be the Brewster angle or an angle in the vicinity thereof.

The reflectance of P-polarized light at the Brewster angle is zero. Therefore, the incident light flux on the light flux coupling element 3 is not reflected on the front surface or the back surface thereof. That is, the incident light beam is only subjected to regular reflection deflection or reflection diffraction by the reflection film of the light beam coupling element 3 or the hologram. As a result, a multiple image such as a double image or a triple image due to multiple reflection in the light beam coupling element 3 does not occur. As a result, in this embodiment, both the image 7 and the image information 8 of the display information of the target liquid crystal display panel 1 can be observed in good condition within the same visual field.

Further, in the present embodiment, the angle θ formed by the optical axis L of the light source means 2 and the normal line of the liquid crystal display panel 1 is relatively inclined so that the angle θ is at or near the Brewster's angle. . Then, the loss due to the light flux of the P-polarized component from the light source means 2 being reflected on the surface of the liquid crystal display panel 1 is eliminated, and the light utilization efficiency is close to 100%. Thereby, the brightness of the image 7 of the display information on the liquid crystal display panel 1 is increased and the visibility is improved.

By increasing the light utilization efficiency as described above, the brightness of the display information image 7 can be increased with low power consumption without increasing the brightness of the light source means 2 too much.

In addition to this, in this embodiment, since the light utilization efficiency can be improved without providing an antireflection film on the liquid crystal display panel, there is a feature that the manufacturing is easy.

[0029]

According to the present invention, a backlight type liquid crystal display panel is used as a display element, and by disposing the liquid crystal display panel at an appropriate angle with respect to the optical axis as described above, an unnecessary multiple reflection image can be displayed. It is possible to achieve a display device in which the utilization efficiency of the light flux is increased while the generation is prevented, the brightness of the image of the display information of the display element is increased, and good observation is possible.

[Brief description of drawings]

FIG. 1 is a schematic view of a main part of an embodiment of the present invention.

FIG. 2 is a schematic view of a main part of a conventional head-up display device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Liquid crystal display panel 2 Light source means 3 Luminous flux coupling element 4 Observer 7 Image of display information 8 Image information

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoko Yoshinaga 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Tetsuro Fukui 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Co., Ltd. (72) Inventor, Yoshika Doshida, 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Innovator, Norio Okuma, 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc.

Claims (3)

[Claims] 1. Display information from a display element and two pieces of image information, which are image information located in different directions from the display information, are spatially superposed through a light transmissive light beam coupling element. In a display device for observing in the same field of view, the display element is composed of a liquid crystal display panel of a backlight system, and the liquid crystal display panel has a normal line to the Brewster angle or an angle in the vicinity thereof with respect to the optical axis. A display device characterized by being arranged so as to be inclined. 2. The display device according to claim 1, wherein the liquid crystal display panel is arranged so as to be inclined such that a normal line thereof is within a range of 30 degrees to 65 degrees with respect to the optical axis. 3. The light flux emitted from the liquid crystal display panel is polarized light vibrating in a plane parallel to the incident surface to the light flux coupling element, and the incident angle to the light flux coupling element is Brewster's angle or the same. The display device according to claim 1, wherein the display device is set to have an angle in the vicinity.