JP3087861B2 - Viewing angle control type display device - Google Patents

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 observing a display image only in an observation area of an observer.

[0002]

2. Description of the Related Art Display devices using CRTs and liquid crystals have made remarkable progress. In particular, liquid crystal display devices are rapidly growing in the field of portable TVs and projectors by taking advantage of their features of thinness, light weight, and low power consumption. Extensive demand is expected not only in markets for broadcasting and video, but also in the field of communications such as TV phones.

In the not-so-distant future, the public is expected to be flooded with various images. Apart from this image, so-called sound from radios, portable cassette tapes, telephones, etc. is flooding the public, but devices such as earphones, headphones or handsets not only protect individual privacy, but also protect third parties. It has a function of preventing the disturbance of the object. The demand for protecting the privacy of images as well as sound is expected to increase in the future.

Hereinafter, a conventional display device using liquid crystal will be described.

FIG. 6 is an example for explaining the principle of the liquid crystal display device. The liquid crystal display device includes, for example, a first polarizing plate 601 and a cell 60 using a twisted nematic liquid crystal.
The second and second polarizing plates 603 are configured as the minimum necessary elements. As shown in FIG. 6A, circularly polarized light 604 from the light source
Becomes linearly polarized light that passes through the first polarizing plate 601.
When no voltage is applied to the liquid crystal cell 602, the direction of polarization of the incident light of this linearly polarized light is rotated by 90 degrees by the twisted liquid crystal. If the polarization direction of the linearly polarized light from the liquid crystal cell 602 is the same as the polarization direction of the second polarizing plate 603, the linearly polarized light emerges from the liquid crystal display without being blocked. On the other hand, as shown in FIG.
When a voltage is applied to 2, the incident light of linearly polarized light into the liquid crystal cell 602 becomes the emitted light of linearly polarized light without changing the polarization direction by passing through the liquid crystal cell 602. The emitted light of this linearly polarized light is blocked because the polarization direction is orthogonal to the polarization direction of the second polarizing plate 603.

FIG. 7 is a sectional view of one pixel in a conventional liquid crystal display device. One pixel is configured based on the principle shown in FIG. The liquid crystal display device has a glass substrate 7
01 on the transparent electrode 7 for applying a voltage to the liquid crystal 702
03, an alignment film 704 for aligning the alignment direction of liquid crystal molecules, and a first film 701 attached to a glass substrate 701.
The polarizing plate 601 and the second polarizing plate 603 are integrally formed. In an actual display device, a screen is composed of thousands, tens of thousands, and hundreds of thousands of pixels.

FIG. 8 is a diagram showing an example of use of a conventional liquid crystal display device. The observer 801 has the display device 8 arranged in front.
It is possible to recognize the image or the character displayed on the image 02. Since the image or the character is displayed on the display device 802, not only the observer 801 but also a third person other than the observer 801 can easily recognize the information.

[0008] In order to prevent the information from being recognized by a third party, there is a head-mounted display device as a device for displaying only the observer 801. FIG. 9 is a diagram illustrating an example of use of a head-mounted display device. Observer 80
1 mounts a hair band type holder 902 on the head, and observes a small head mounted display device 903 attached to the holder 902 with one eye.

FIG. 10 shows the principle of the head-mounted display device 903. This display device includes a single diode array 1001 and a lens 1 arranged in a large number in a line.
002 and a movable mirror 1003 rotating at high speed. The display information is sequentially displayed one line at a time from the light emitting diode array 1001, and the movable mirror 1003 is rotated in synchronization with the switching of the information of one line to form display information for one frame. The observer looking at the movable mirror 801 is as if it were a light emitting diode array 1001
Appear to constitute one frame. The head-mounted display device 903 also has an advantage that, although the physical screen size is small, an illusion of looking at an A4-size screen is obtained.

[0010]

As described above,
The head-mounted display device is a private display device for the observer only. However, the observer cannot observe the display surface with only one eye, and the observer must wear a device with a certain weight on his / her head. Could not be avoided.

Further, when the head-mounted display device is applied to a videophone device, the camera always takes a human image with the head-mounted display device attached, and the image is transmitted to the partner terminal. I feel uncomfortable.

An object of the present invention is to solve the above-mentioned disadvantages of the prior art and to provide a viewing angle control type display device capable of privatizing a display screen without attaching any special device to an observer.

[0013]

SUMMARY OF THE INVENTION A viewing angle control type display device according to the present invention includes a surface light source and a plurality of shutter regions, each of which can be switched between a light transmitting region and a light blocking region by an electric signal. An optical shutter plate, an optical path control plate including a microlens having a function of condensing light emitted from the surface light source to a predetermined position, which has been transmitted through the light transmitting region of the shutter plate, and And a transmission type display device that forms a display screen using light as a light source.

[0014]

According to the present invention, a part of the light emitted from the surface light source in all directions passes through the optical shutter plate,
The optical shutter plate acts as a point light source or a line light source. In addition, since the light path control plate formed of a microlens covers the light source, the light emitted from the light source is focused on an observation position determined by the positional relationship between the light source and the microlens. Since the transmissive display device is present between the optical path control plate and the observation position, the display image reaches the observation position. Therefore, the image can be observed only in the light-collecting region without attaching any special device to the observer, and the display screen can be privatized.

[0015]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of a viewing angle control type display device according to one embodiment of the present invention.

This viewing angle control and display device includes a surface light source 10
1. An optical shutter plate 102, an optical path control plate 103, and a transmission type display device 104. Optical shutter plate 1
Reference numeral 02 here includes a first polarizing plate 105 for an optical shutter, a twisted nematic liquid crystal cell 106, and a second polarizing plate 107 for an optical shutter. The transmissive display device 104 includes a twisted nematic liquid crystal cell for display 108 and a third polarizing plate 109 for display.

Non-directional light having circular polarization emitted from the surface light source 101 is converted into linearly polarized light after passing through a first polarizing plate 105 which is a component of the optical shutter plate 102. This linearly polarized light is applied to the twisted nematic liquid crystal cell 1.
06, the polarization direction is rotated by 90 degrees when passing through the pixel in the ON state, while after passing through the pixel in the OFF state,
The polarization direction passes without change. Polarization direction is 9
Only light that has changed by 0 degrees can pass through the second polarizing plate 107. Therefore, by utilizing the polarization control of the liquid crystal, a light passing region can be formed at an arbitrary position on the optical shutter plate 102. The transmitted light is the light shutter plate 1
Depending on the passing position at 02 and the positional relationship of the lens on the optical path control plate 103, directivity is obtained in a specific direction. The light emitted from the optical path control plate 103 has not only a fixed polarization direction but also uniform directivity. The linearly polarized light having this directivity functions as a light source in the transmission type display device 104. Twisted nematic liquid crystal cell 1
At 08, the polarization direction is controlled in accordance with the display signal, and the light is analyzed by the third polarizing plate 109 to obtain a display image. This display image reaches a specific observation area from the above description.
Therefore, the display screen can be privatized without attaching any special device to the observer.

FIG. 2A is a diagram for explaining the light condensing action of the lenticular lens 201 serving as the optical path control plate 103 and the optical shutter plate 102. The vicinity of the center of the optical shutter plate 102 and the position in the horizontal direction are shown. 4 shows the result of simulating ray tracing of the light emitted from. Also,
An enlarged view near the center (FIG. 2 (2)) is also shown. A plurality of shutter regions are formed in the pitch of the lenticular lens 201. Here, as an example, the window near the center is opened (selected pixel 205) (FIG. 2 (3)). Light from the surface light source 101 passes through the window and spreads toward the center by the lenticular lens 201. This spread can be controlled by the size of the window or the relationship between the thickness of the lenticular lens 201 and the focal length. As in the vicinity of the center, the light passing through the left and right windows spreads in the left and right directions. The overlapping area of each spread light becomes the observation area 204. Light spreading due to the sidelobes 203 is also observed in an area other than the observation area 204. The side lobe 203 is light from a source other than the lens that generates the main lobe 202.

In the above embodiment, the case where the lattice-shaped shutter region is provided in the twisted nematic liquid crystal cell 108 for the optical shutter has been described. However, the present invention is not limited to this. Can be implemented. Further, the optical path control plate 103 may be composed of two lenticular lenses 201 arranged orthogonally to each other.

FIG. 3 is a sectional view of the lenticular lens 301 with a black stripe. Side robe 203
Is more effective as a method of driving the outside of the observation area 204.

FIG. 4 is a diagram showing a lens form used for a microlens. FIG. 1A shows a lenticular lens 201, which can provide directivity in either the left or right or up and down directions. FIG. 2B shows a fly-eye lens 401.
Both left and right and up and down directivities are obtained.

FIG. 5 shows an example of a functional configuration for tracking the head of the observer. The solid line is a light path, and the broken line is an electric signal. Light emitted from the surface light source 101 is emitted from the transmissive liquid crystal device 104 with directivity as described above. The directivity is determined by the positional relationship between the shutter area of the optical shutter plate 102 and the microlenses of the optical path control plate 103. Since the position of the microlens is fixed, directivity can be controlled by changing the shutter area.
This directivity control can be realized by detecting the position of the observer's head with the head detector 501 and feeding back a control signal corresponding to the movement of the observer's head to the optical shutter plate 102.

[0024]

As described above, the present invention has the following effects.

(1) According to the first aspect of the present invention, an image can be observed only in a light condensing area by disposing an optical shutter plate and an optical path control plate between a surface light source and a transmission type display device. The display screen can be privatized without attaching the device to the observer.

(2) According to the second aspect of the present invention, by forming the optical shutter plate with a liquid crystal panel, a light passing region can be formed at an arbitrary position by utilizing the polarization control of the liquid crystal.

(3) According to the third aspect of the invention, by forming the optical path control plate with a lenticular lens, the side lobes can be driven outward from the observation area, and the directivity of either the left, right, up, or down can be obtained. .

(4) According to the fourth aspect of the invention, since the optical path control plate is formed of a fly-eye lens, both the left and right and the up and down directivities are obtained.

(5) According to the fifth aspect of the present invention, since the light incident on the transmission type display device has the same direction of deflection as well as the traveling direction, a polarizing plate for converting the light into linearly polarized light is not required. Inexpensive and bright display screen.

(6) According to the invention of claim 6, the directivity of light passing through the optical shutter plate can be controlled by having the head detector.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a viewing angle control type display device according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining light condensing action by a lenticular lens 201 as an optical path control plate 103 and an optical shutter plate 102;

FIG. 3 is a sectional view of a lenticular lens with a black stripe.

FIG. 4 is a diagram showing a lens configuration used for a micro lens.

FIG. 5 is a diagram illustrating a configuration example of a function of tracking the head of an observer.

FIG. 6 is a diagram illustrating the principle of a liquid crystal display device.

FIG. 7 is a diagram showing a cross-sectional structure for one pixel in a conventional liquid crystal display device.

FIG. 8 is a diagram illustrating an example of use of a conventional liquid crystal display device.

FIG. 9 is a diagram illustrating an example of use of a conventional head-mounted display device.

FIG. 10 is a principle diagram of a head mounted display device.

[Explanation of symbols]

Reference Signs List 101 surface light source 102 optical shutter plate 103 optical path control plate 104 transmission type display device 105 first polarizing plate for optical shutter 106 twisted nematic liquid crystal cell for optical shutter 107 second polarizing plate for optical shutter 108 twisted nematic liquid crystal for display Cell 109 Third polarizer for display 201 Lenticular lens 202 Main lobe 203 Side lobe 204 Observation area 205 Selected pixel 301 Lenticular lens with black stripe 401 Fly-eye lens 501 Head detector 601 First polarizer 602 Twist Nematic liquid crystal cell 603 Second polarizing plate 604 Circularly polarized light 701 Glass substrate 702 Liquid crystal 703 Transparent electrode 704 Alignment film 801 Observer 802 Display device 902 Holder 903 Head mounted display device 1 001 LED array 1002 Lens 1003 Movable mirror

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI G09F 9/00 328 G09F 9/00 331Z 331 G02B 27/00 FL (72) Inventor Susumu Ichinose 1-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (58) Fields surveyed (Int.Cl. ⁷ , DB name) G02F 1/1335 G02B 27/00 G02F 1/1347 G02F 1/29 G09F 9/00 327 G09F 9/00 328 G09F 9 / 00 331

Claims (6)

(57) [Claims] 1. An optical shutter plate including a surface light source, a plurality of shutter regions, each of which can be switched between a light transmitting region and a light blocking region by an electric signal, and a light transmitting region of the shutter plate. A light path control plate comprising a microlens having a function of condensing light emitted from the surface light source to a predetermined position; and a transmission type display device for forming a display screen using light from the light path control plate as a light source. Viewing angle control type display device. 2. The optical shutter plate comprises: a first polarizing plate;
A liquid crystal panel comprising a polarization control element made of liquid crystal and a second polarizing plate, wherein a grid-like or stripe-like shutter region is formed on the liquid crystal panel, and the shutter region can be controlled by an electric signal. Item 1
The viewing angle control type display device according to the above. 3. The optical path control plate is a single lenticular land or two lenticular lands arranged perpendicular to each other.
Lenticular lens, one of which
3. The viewing angle control type display device according to claim 1, wherein the pitch region includes a plurality of shutter regions. 4. The viewing angle control device according to claim 1, wherein the optical path control plate is formed of a fly-eye lens, and one pitch region of the lens includes a plurality of shutter regions. 5. The viewing angle control type display device according to claim 1, wherein the transmission type display device has a polarization control element made of liquid crystal and a third polarizing plate as minimum components. 6. A head detector for detecting the position of the observer's head, and the observation area is controlled by a control signal from the head detector to an optical shutter plate according to the movement of the observer's head. The viewing angle control type display device according to any one of claims 1 to 5, which is movable.