JPH04358123A - Display device - Google Patents

Abstract

PURPOSE:To make the display device easy to use and improve the man-machine interface. CONSTITUTION:A polarizing direction control element 101 (e.g. twisted nematic type liquid crystal) which rotates the polarization direction with an electric signal is arranged in front of an observer 501 and a display information selecting element 102 is arranged right before the observer; and linear polarized light transmitted in a 1st polarizing plate is optically rotated or transmitted without being rotated in the polarizing direction control element 101 like twisted nematic liquid crystal according to display information, and this optically rotated or transmitted light is selectively passed through the optical display information selecting means 102 right before the observer to obtain private display information.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device capable of protecting the privacy of an observer.

0002

2. Description of the Related Art There has been remarkable progress in display devices using CRTs and liquid crystals. In particular, liquid crystal display devices take advantage of their features such as thinness, light weight, and low power consumption to be used in mobile TVs and even
The market for projectors that can project images onto large screens is rapidly growing. As described above, a huge demand for display devices is expected not only in the entertainment market such as broadcasting and video, but also in the communication field.

[0003] In order to build a smoother man-machine interface, video telephones using images as media have become essential. It is thought that the market for entertainment and the market for communication will not only be limited to homes and offices, but will also penetrate deeply into the public, such as on trains, buses, and parks.

[0004] In the not too distant future, it is expected that the public will be flooded with various images. In addition to this image, so-called sounds from radios, portable cassette tapes, telephones, etc.
Although they have become widespread in the public, devices such as earphones, headphones, and handsets not only protect personal privacy, but also play a role in preventing interference with third parties. It is thought that the demand for privacy protection for images, like that for sounds, will increase in the future.

[0005] A display device using liquid crystal will be explained below.

FIG. 3 is an example diagram for explaining the principle of a liquid crystal display device. The liquid crystal display device is configured with, for example, a first polarizing plate 301, a twisted nematic liquid crystal cell 302, and a second polarizing plate 303 as the minimum required elements.

As shown in FIG. 3(1), circularly polarized light 304 from a light source (not shown) becomes linearly polarized light when it passes through a first polarizing plate 301. As shown in FIG. When no voltage is applied to the liquid crystal cell 302, the linearly polarized incident light 305 has its polarization direction changed by 90 degrees by the twisted nematic liquid crystal. If the polarization direction of the linearly polarized light 306 emitted from the liquid crystal cell 302 is the same as the polarization direction of the second polarizing plate 303, the light will not be blocked and will come out of the liquid crystal display device.

On the other hand, as shown in FIG. 3(2), the liquid crystal cell 3
When a voltage is applied to 02, the linearly polarized incident light 305 to the liquid crystal cell 302 becomes the linearly polarized outgoing light 306 without changing the polarization direction by passing through the liquid crystal cell 302.
becomes. This linearly polarized outgoing light 306 has a polarization direction in the second direction.
Since the light is perpendicular to the polarization direction of the polarizing plate 303, it is blocked.

FIG. 4 is a cross-sectional structural diagram of one pixel in a conventional liquid crystal display device. One pixel is constructed based on the principle explained in FIG. 3 above. The liquid crystal display device includes a transparent electrode 403 on a glass substrate 401 for applying a voltage to a liquid crystal 402, an alignment film 404 for aligning the orientation direction of liquid crystal molecules, and a first polarized light attached to the glass substrate 401. A plate 405 (corresponding to 301 in FIG. 3) and a second polarizing plate 406 (corresponding to 303 in FIG. 3) are integrally formed. In an actual display device, a screen is composed of thousands, tens of thousands, or hundreds of thousands of pixels.

FIG. 5 is a diagram showing an example of the use of a conventional liquid crystal display device. An observer 501 can recognize images or characters displayed on a display device 502 placed in front of him. Since images or characters are displayed on the display device 502, not only the observer 501 but also a third party other than the observer 501 can easily recognize the information.

[0011] In order to prevent information from being recognized by a third party, a head-mounted display device is available as a display device that displays information only for the observer 501. FIG. 6 shows an example of how the head-mounted display device is used. Observer 5
01 wears a hairband-shaped holder 602 on his head and observes a small display device 603 attached to the holder 602 with one eye.

FIG. 7 shows a principle diagram of the head-mounted display device. This display device is composed of a single light emitting diode array 701 arranged in a linear manner, a lens 702, and a movable mirror 703 that rotates at high speed.

Display information is sequentially displayed one line at a time from the light emitting diode array 701, and the movable mirror 703 is rotated in synchronization with switching of one line of information to form one frame of display information.

Observer 501 looking at movable mirror 703
It looks as if the light emitting diode array 701 constitutes one frame. This head-mounted display device has the advantage of giving the illusion of looking at an A4-sized screen, even though the physical screen size is small.

[0015]

[Problems to be Solved by the Invention] In the head-mounted display device as described above, although it is a private display device only for the observer, the display surface can only be observed with one eye. It was unavoidable that the observer would be burdened by having to wear a device with a certain amount of weight on his or her head.

Furthermore, if a head-mounted display device is applied to a videophone device, the camera will always take an image of the person wearing the head-mounted display device, and that image will be transmitted to the other party's terminal. A sense of discomfort arises.

As described above, in the prior art, there has been no display device that is easy to use and can improve the human interface.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a private display device which eliminates the above-mentioned problems of the prior art, is easy to use, and can improve the human interface.

[0019]

[Means for Solving the Problems] The present invention has means for selectively obtaining display information using the polarization direction of light, and includes at least a first polarizing plate and an electrical signal to rotate the polarization direction. In a display device that is integrally configured with a polarization direction control element, such as a twisted nematic liquid crystal, and a second polarizing plate that selectively transmits polarized light, the display information selection element made of the second polarizing plate is configured to It is characterized in that it is configured separately from the polarizing plate and the polarization direction control element, and is placed in front of the observer.

[0020]

[Operation] According to the present invention, linearly polarized light passing through the first polarizing plate is rotated or not rotated in a polarization direction control element such as a twisted nematic liquid crystal based on display information. Private display information can be obtained by selectively passing the transmitted light in front of the observer's eyes.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a cross-sectional structure of one pixel in a polarization direction control element 101 of a display device according to an embodiment of the present invention. One pixel is constructed based on the principle explained in FIG. The liquid crystal display device includes a transparent electrode 403 for applying a voltage to a liquid crystal 402 and an alignment film 404 for aligning the alignment direction of liquid crystal molecules, which are integrally formed on a glass substrate 401. Compared to the conventional liquid crystal display device shown in FIG. 4, it includes only one polarizing plate (second polarizing plate 406) instead of two, first and second polarizing plates 405 and 406.

FIG. 2 is a diagram showing an example of use of the display device of the present invention. An observer 501 can view the display screen by placing the display information selection element 102 made of a second polarizing plate in front of him.

That is, since light polarized in various directions passes through thousands or tens of thousands of pixels and is emitted from the polarization direction control element 101 placed in front of the observer 501, the polarization direction The control element 101 only appears to be shining brightly. However, the observer 501 who has the display information selection element 102 in front of him can obtain the display information, and a third party who does not have the display information selection element 102 cannot obtain any display information.

[0024] In the above embodiment, only the case of a transmissive type using liquid crystal was explained, but the present invention is not limited to this, and a reflective type can be implemented in exactly the same way.

Further, in the above embodiment, only the case where liquid crystal is used as the polarization direction control element has been described, but the invention is not limited to this, and any material that rotates the polarization direction may be used.

Furthermore, although the above embodiment does not describe the form of the polarizing plate constituting the display information selection element 102, for example, glasses with polarizing plates attached, or
If used for communication, a polarizing plate may be attached to the handset. In either method, any form may be used as long as the display information selection element is placed in front of a limited number of viewers.

[0027]

As explained above, the display device of the present invention includes a first polarizing plate, a polarization direction control element that rotates the polarization direction by an electric signal, and a second polarization direction control element that selectively transmits polarized light. In a display device having a display information element consisting of a plate, the display information selection element is configured separately from the first polarizing plate and the polarization direction control element, and is placed in front of the viewer, so that other than the viewer It is possible to provide a display device that protects the privacy of individuals by not providing display information to third parties.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional structure of one pixel in a polarization direction control element of a display device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of use of the display device of the present invention.

FIG. 3 is an example diagram for explaining the principle of a liquid crystal display device.

FIG. 4 is a cross-sectional structural diagram of one pixel in a conventional liquid crystal display device.

FIG. 5 is a diagram illustrating a usage example of a conventional liquid crystal display device.

FIG. 6 is a diagram illustrating a usage example of a conventional head-mounted display device.

7 is a principle diagram of the head-mounted display device of FIG. 6. FIG.

[Explanation of symbols]

101... Polarization direction control element, 102... Display information selection element, 301, 405... First polarizing plate, 302
...Twisted nematic liquid crystal cell, 303,40
6...Second polarizing plate, 304...Circularly polarized light, 305...
Linearly polarized incident light, 306...Linearly polarized outgoing light,
401...Glass substrate, 402...Liquid crystal, 403
...transparent electrode, 404...alignment film, 501...observer, 502, 603...display device, 602...holder,
701...Light emitting diode array, 702...Lens, 703...Movable mirror.

Claims (2)

[Claims] 1. At least a first polarizing plate, a polarization direction control element that rotates the polarization direction by an electric signal,
In a display device having a display information selection element made of a second polarizing plate that selectively transmits polarized light, the display information selection element made of the second polarizing plate is connected to the first polarizing plate and the polarization direction control element. A display device configured separately from the display device and placed in front of an observer. 2. The display device according to claim 1, wherein the polarization direction control element includes at least a liquid crystal as one of its constituent elements.