GB2116399A

GB2116399A - 3-Dimensional television

Info

Publication number: GB2116399A
Application number: GB08305889A
Authority: GB
Inventors: Robert Frederick Oxley
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-03-04
Filing date: 1983-03-03
Publication date: 1983-09-21
Also published as: GB8305889D0

Abstract

A method of achieving 3- dimensional television in which images from two signals are displayed alternately on a television screen and including means for synchronising the viewing by each eye with the alternating displayed images. The alternating images preferably correspond to the output of two video cameras which are positioned in such a way to simulate binocular vision. The viewing period of the screen by each eye is arranged to be synchronised with the display periods of the alternating sequence of images so that the left eye receives light from the screen when one of the output signal images is displayed and the right eye receives light from the screen when the other of the output signal images is being displayed. The optical switching of the images between eyes may be carried out by spectacles containing Kerr effect or liquid crystal cells or voltage sensitive glass or mechanical shutters.

Description

SPECIFICATON 3-dimensional television The present invention is concerned with 3dimensional television.

Several methods have been proposed previously for achieving 3-dimensional television viewing.

Possibly the earliest technique proposed for this purpose is that which involves displaying simultaneously a pair of monochromatic images, one in red and the other in blue or green. The viewer wears a pair of spectacles with a corresponding red filter over one eye and a blue or green filter over the other eye. The spectacles effecively blank out the unwanted image to each eye whereby each eye "sees" a separate image which the brain combines to form a 3-dimension view. This system works well but has the disadvantage that only black and white reproduction is possible.

Another known technique makes use of polarised spectacles through which polarised images from two separate screens are viewed via a semi-reflector which optically superimposes the images from the two screens. Polarising screens are placed over each screen to prevent each eye from seeing what should only be seen by the other eye. Althouth full colour can be achieved, the reproduction apparatus is bulky in this instance since two screens are required. Also, the resulting image lacks brightness due to the light intensity being reduced by the various polarising screens and glasses.

A third known technique splits the image into two entirely separate images which are displayed on the left and right hand sides of the screen respecdvely. A viewing hood over the screen contains prismatic lenses which bend the viewing paths so that the viewer's eyes can take in both pictures. The problem with this system is that it can only be viewed by one person at a time, that is there must be a display set for each viewer.

Another known technique makes use of a socalled lenticular screen which comprises an array of vertically disposed cylindrical lenses which direct left and right eye images in slightly different directions. No special spectacles are necessary but this method involves a restriction on how far the viewer can turn his head and it thus imposes a restriction on where the viewer sits.

It is an object of the present invention to provide a system for displaying 3-dimensional television images in full colour in which the problems and disadvantages of the aforegoing known techniques are reduced.

In accordance with the present invention there is provided a method of achieving 3dimensional television comprising synchronising the viewing by each eye with alternating displayed images from two positions.

The alternating images can correspond to the outputs of two video cameras, or the like, positioned in such a way as to simulate binocular vision, the resulting two output signals being displayed on the t.v. screen alternately in rapid sequence. The eye is conscious of flicker to an extent dependent on the brightness of the display, the frequency with which the intensity varies and the viewing angle. It is believed that flicker will be avoided if the images are displayed alternately, preferably at a frequency in excess of 25 times per second.The viewing period of the screen by each eye is then arranged to be synchronised with the display periods of the alternating sequence of images so that the left eye substantially only receives light from the screen when the image from a first of the two video cameras is being displayed and the right eye substantially only receives light from the screen when the image from the other of the two video cameras is being displayed. Thus, the screen is viewed alternately by one eye and then the other in rapid succession to effect a 3-D view of the scene.

In order to ensure that each eye only "sees" the image from a respective one of the cameras, it is necessary sequentially to block the light received by each eye in synchronism with the alternating images on the screen. This may be effected by a viewing device using, for example, the Kerr effect or liquid crystals mounted in spectacles or a lorgnette so as to blank each eye alternately, or special voltage-sensitive glass suitable for switching of approximately 60 fields per second. Alternatively, a mechanical means such as miniature Venetian blinds could be used.

The synchronism between the viewing device and the alternating images can be effected by wire between the t.v. set and the viewing device or, alternatively by infra red or ultrasonic signals in a similar manner to that used presently in conventional remote controlled t.v. sets.

In an alternative system, the two video cameras in the aforegoing embodiment could be replaced by a single video camera having an optical device such as an oscillating prism or electronic deflection device arranged such that the camera generates a stereoscopic picture signal.

In transmitting the signals, one possibility would be to send the two signals as consecutive fields of an interlaced system. In order to provide for monoscopic viewing of such signals, means would be provided in the receiver to repeat one of the two signals transmitted and to suppress the other. For example by employing a field or frame period delay.

The signals are transmitted at either the field or frame frequency of the system. Only a single picture tube is required.

Claims

1. A method of achieving 3-dimensional television comprising synchronising the viewing by each eye with alternating displayed images from two positions.

2. A method as claimed in claim 1 in which the alternating images correspond to the outputs of two video cameras, or the like, positioned in such a way as to simulate binocular vision, the

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATON 3-dimensional television The present invention is concerned with 3dimensional television. Several methods have been proposed previously for achieving 3-dimensional television viewing. Possibly the earliest technique proposed for this purpose is that which involves displaying simultaneously a pair of monochromatic images, one in red and the other in blue or green. The viewer wears a pair of spectacles with a corresponding red filter over one eye and a blue or green filter over the other eye. The spectacles effecively blank out the unwanted image to each eye whereby each eye "sees" a separate image which the brain combines to form a 3-dimension view. This system works well but has the disadvantage that only black and white reproduction is possible. Another known technique makes use of polarised spectacles through which polarised images from two separate screens are viewed via a semi-reflector which optically superimposes the images from the two screens. Polarising screens are placed over each screen to prevent each eye from seeing what should only be seen by the other eye. Althouth full colour can be achieved, the reproduction apparatus is bulky in this instance since two screens are required. Also, the resulting image lacks brightness due to the light intensity being reduced by the various polarising screens and glasses. A third known technique splits the image into two entirely separate images which are displayed on the left and right hand sides of the screen respecdvely. A viewing hood over the screen contains prismatic lenses which bend the viewing paths so that the viewer's eyes can take in both pictures. The problem with this system is that it can only be viewed by one person at a time, that is there must be a display set for each viewer. Another known technique makes use of a socalled lenticular screen which comprises an array of vertically disposed cylindrical lenses which direct left and right eye images in slightly different directions. No special spectacles are necessary but this method involves a restriction on how far the viewer can turn his head and it thus imposes a restriction on where the viewer sits. It is an object of the present invention to provide a system for displaying 3-dimensional television images in full colour in which the problems and disadvantages of the aforegoing known techniques are reduced. In accordance with the present invention there is provided a method of achieving 3dimensional television comprising synchronising the viewing by each eye with alternating displayed images from two positions. The alternating images can correspond to the outputs of two video cameras, or the like, positioned in such a way as to simulate binocular vision, the resulting two output signals being displayed on the t.v. screen alternately in rapid sequence. The eye is conscious of flicker to an extent dependent on the brightness of the display, the frequency with which the intensity varies and the viewing angle. It is believed that flicker will be avoided if the images are displayed alternately, preferably at a frequency in excess of 25 times per second.The viewing period of the screen by each eye is then arranged to be synchronised with the display periods of the alternating sequence of images so that the left eye substantially only receives light from the screen when the image from a first of the two video cameras is being displayed and the right eye substantially only receives light from the screen when the image from the other of the two video cameras is being displayed. Thus, the screen is viewed alternately by one eye and then the other in rapid succession to effect a 3-D view of the scene. In order to ensure that each eye only "sees" the image from a respective one of the cameras, it is necessary sequentially to block the light received by each eye in synchronism with the alternating images on the screen. This may be effected by a viewing device using, for example, the Kerr effect or liquid crystals mounted in spectacles or a lorgnette so as to blank each eye alternately, or special voltage-sensitive glass suitable for switching of approximately 60 fields per second. Alternatively, a mechanical means such as miniature Venetian blinds could be used. The synchronism between the viewing device and the alternating images can be effected by wire between the t.v. set and the viewing device or, alternatively by infra red or ultrasonic signals in a similar manner to that used presently in conventional remote controlled t.v. sets. In an alternative system, the two video cameras in the aforegoing embodiment could be replaced by a single video camera having an optical device such as an oscillating prism or electronic deflection device arranged such that the camera generates a stereoscopic picture signal. In transmitting the signals, one possibility would be to send the two signals as consecutive fields of an interlaced system. In order to provide for monoscopic viewing of such signals, means would be provided in the receiver to repeat one of the two signals transmitted and to suppress the other. For example by employing a field or frame period delay. The signals are transmitted at either the field or frame frequency of the system. Only a single picture tube is required. Claims

2. A method as claimed in claim 1 in which the alternating images correspond to the outputs of two video cameras, or the like, positioned in such a way as to simulate binocular vision, the resulting two output signals being displayed on the t.v. screen alternately in rapid sequence.

3. A method as claimed in claim 1 or 2 in which the viewing period of the screen by each eye is arranged to be synchronised with the display periods of the alternating sequence of images so that the left eye substantially only receives light from the screen when the image from a first of the two video cameras is being displayed and the right eye substantially only receives light from the screen when the image from the other of the two video cameras is being displayed.

4. A method as claimed in any of claims 1, 2 or 3 in which the light is blocked from each eye in synchronism with the alternating images on the screen.

5. A method as claimed in claim 4 in which the light is blocked by means of a viewing device using the Kerr effect or liquid crystals mounted in spectacles or a lorgnette so as to blank each eye alternately, or special voltage-sensitive glass.

6. A method as claimed in claim 4 in which the light is blocked by a viewing device having a mechanical shutter means.

7. A method as claimed in any of claims 5 or 6 in which the synchronism between the viewing device and the alternating images is effected by wire between the television set and the viewing device.

8. A method as claimed in any of claims 5 or 6 in which the synchronism between the viewing device and the alternating images is effected by infra red or ultrasonic signals.

9. A method as claimed in claim 1 in which the alternating displayed images are derived from a single video camera having an optical device for generating a stereoscopic picture signal.

10. A method as claimed in claim 9 in which the optical device comprises an oscillating prism or electronic deflection device.

11. A method of achieving 3-dimensional television substantially as hereinbefore described.