GB2160381A

GB2160381A - Stereoscopic TV system

Info

Publication number: GB2160381A
Application number: GB08414843A
Authority: GB
Inventors: Felipe Herman Arizcorreta
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-06-11
Filing date: 1984-06-11
Publication date: 1985-12-18
Also published as: JPS613595A; FR2565755A1; GB8414843D0; DE3421652A1; NL8401860A

Abstract

A stereoscopic TV system comprises a stereoscopic TV camera having two separate optical means and a servocontrol for focusing said optical means both for parallax and depth, for producing two stereo images, light sensitive means coupled to each one of said optical means to convert said stereo images into corresponding video signals, high speed switcher means to alternate passage of the video signals provided by said light sensitive means, TV signals transmitter means for transmitting the alternated video signals passing through said switcher means, TV signals receiver means for receiving said transmitted TV signals and converting them into video signals through deflecting coil means producing a scan in an image tube, such that said alternated video signals are arranged on the screen as an alternated series of vertical video straps of stereoscopic signals and a stereo refracting xographic screen superposed to the image forming screen of the image tube, said xographic screen comprising a plurality of vertical semicylindrical aspherical lenses to refract in opposite angular directions the alternated switched signals of each adjacent pair of said video straps, so as to produce a pair of diverging refracted beams to permit perception of a three-dimensional image. <IMAGE>

Description

SPECIFICATION Stereoscopic TV system The present invention refers to a stereoscopic TV system and, more particularly, it is related to a stereoscopic television transmission and reception system capable of producing a pair of stereoscopic signals that may be separately perceived by the eyes of the observer without the use of image separating spectacles.

The possibility of producing a stereoscopic or three-dimensional image on television receivers, has not been thought of as a practical matter, because if two superposed images are transmitted by the transmitter and received by the receiver to be watched by the observer, who will of course have to use the same type of glasses that have been traditionally used in connection with stereoscopic movie pictures, then apart from the discomfort produced in the watchers of the TV set, other factors render the system completely unacceptable, because when not using the spectacles, the watchers of the TV receiver will not be able to watch a well defined image, because of the superposition of the two images that should be made for producing the stereoscopic sensation.On the other hand, the mere fact that the transmission and reception of television signals depends on the scanning of the screen by an electron beam in itself has rendered the transmission of two superposed images practically unobtainable, whereby no workers in the prior art have endeavoured to develop a system for the transmission of stereoscopic television signals for being watched by the observers.

In view of the above mentioned apparent difficulties, the workers in the television field have not even thought it to be possible to transmit stereoscopical or three-dimensional images for being watched by the observers either wearing or not wearing suitable spectacles, whereby the field of stereoscopic television is entirely empty since no development or innovation has been made in this field by the workers in the art.

The present invention provides a stereoscopic TV system which permits watching a stereoscopical or three-dimensional image in a TV receiver, and comprising a stereoscopic TV camera having two separate optical means and a servocontrol for focusing said optical means both for convergence and depth, for producing two stereo images, light sensitive means coupled to each one of said optical means to convert said stereo images into corresponding video signals high speed switcher means to alternate passage of the video signals produced by said light sensitive means, TV signals transmitter means for transmitting the alternated video signals passing through said switcher means, TV signals receiver means for receiving said transmitted TV signals and converting them into video signals through deflecting coil means arranged in an image tube, and a xographic screen placed on the image receiving screen of the image tube, said xographic screen comprising a plurality of vertical semicylindrical lenses to refract in opposite angular directions the alternated switched signals received, so as to produce perception of a threedimensional image by means of refracting one of the stereo video signals on one of the eyes of the observer and the other of said stereo video signals on the other eye of the observer.

The present invention will best be understood from the following description of certain specific embodiments, when read in conjunction with the accompanying drawings, in which: Figure lisa block diagram of the various components constituting the stereoscopic TV system built in accordance with the present invention; Figure 2 is a diagrammatic perspective view of the stereoscopic TV cameras for use with the system of the present invention; Figure 3 is a diagrammatical plan view of the stereoscopical camera for use in the system of the present invention, showing the colinear relationship between the optical assemblies and the light sensitive devices for transforming the optical images into video signals and with the camera focused to infinity; Figure 4 is a view similar to Figure 3, but showing the camera focused on a nearby object;; Figure 5 is a diagrammatical fragmentary view of part of the TV receiver screen and xographic screen superposed thereto, in order to illustrate the relationship between the positions of said xographic screen with respect to the vertical bands of the video screen wherein the left and right images are formed; Figure 6 is a diagram of the left and right photograms showing the manner in which the light beams corresponding to the two different stereo bands are refracted by the aspherical lenses of the xographic screen; Figure 7 is a block diagram of the signal commuting circuit for the stereoscopical camera;; Figure 8 is a figure representing superposed graphs of the electrical signals produced by the clock used in the circuit of the present invention, the electrical signals generated in divided alternate time cues for the left and right controls of the switchers, and the commuted video signals; Figure 9 is a diagrammatic view of the screen of the receiver of the present invention, showing the vertical scanning mode of the system of the present invention; and Figure 10 is an electrical clocked diagram of the deflecting coils for producing stereo and non-stereo signals, in the vertical scanning mode of the system for stereo vision and horizontal scanning mode for non stereo vision.

In accordance with the present invention, the novel system provided for transmitting and recieving stereo video signals attempts to modify both the transmission of TV signals and the reception thereof, by permitting the observer to have the sensation of watching three-dimensional images, as well as also certain modifications to a TV camera, switcher and receiver apparatus, all of them built in accordance with one of several standards of common use through the world, such as NTSC, PAL, SECAM and the like. This represents a breakthrough in the field of television, since for the first time an apparatus is provided which permits watching three-dimensional images rather than only bidimensional images as is the case of the prior art systems.

It is to be reminded that, when using the eyes, that is, when using binocularvision,the human brain is capable of feeling the signals transmitted by the eyes in three-dimensional manner because of the difference in the position of the points of vision, which motivate certain slight differences in the observation of objects located in nearby points as related to objects which are at distant points. In this manner, the human brain receives two different images, merging the same in order to form one single three-dimensional image.

The average distance between the human eyes, which are located at the centre of the face and displace in a horizontal plane, is of approximately 60 mm, which is the interocular distance in human beings. As mentioned above, the different images perceived by each eye of the pair are interpreted by the brain merging the same in one single stereoscopic image or three-dimensional image which contains height, width and depth.

The camera used in the TV system of the present invention, as illustrated in Figures 2 and 3, and to be described in more detail hereinbelow, therefore, imitating the human eyes, comprises two optical assemblies 12 and 13, instead of one single optical assembly as the TV cameras broadly used in prior art systems, in order to accomplish the obtention of a double image which will thereafter produce in the human brain the perception of a three-dimensional single image. The normal horizontal distance of spacing between said optical assemblies, therefore, must be the same at the antropomorphic measure of approximately 60 mm.

The complete system of the present invention as illustrated in Figure 1 of the drawings, essentially comprises one TV camera provided with two optical assemblies as mentioned above, which contain the customary elements to transform the optical images into video electronic signals which are sent through suitable lines 25 and 26 to a commuting device 2 which comprises a high frequency switcher 2 to be described in more detail hereinafter, in order to switch the passage of said two video signals arriving through lines 25 and 26, such that only one of said signals is allowed to pass in a predetermined time, through the commuter device which is arranged such that it will accurately and strictly alternate the two video signals, namely, the left and the right signals, as will also be described in more detail hereinbelow.The alternated video signals are sent through a suitable line 27 to a transmitter 3, which will transmit said signal as is very well known in the prior art, either through suitable antenna, a cable, a carrier or the like, in the form of electromagnetic waves 28 which will be perceived by the corresponding antenna or cable of a TV receiver4which contains, besides the normal image screen of the image tube, an additional xographic screen containing a plurality of vertically arranged semicylindrical aspherical lenses as also will be described hereinbelow. The image tube of the TV receiver 4, will contain the normal deflection coils which may or may not be modified, in accordance with the embodiments of the invention that may be used as will also be described in more detail hereinbelow.

As already mentioned above, the TV camera bult in accordance with an embodiment of the present invention which is illustrated in Figures 2, 3 and 4 of the drawings, comprises a pair of optical assemblies 12 and 13 which, as clearly shown in Figure 3 of the drawings, may be arranged parallel to each other, in order to focus very distant objects, that is, objects located at a practically infinite distance, very much as the human eyes are also arranged such that their lines of vision will be almost parallel for focusing distant objects, and will be capable of focusing nearby objects by means of the provision of a suitable servomechanism (very well known and not shown) and a telemetric system, in order to place the access of the optical assemblies 12 and 13 such that their lines of vision will form an angle which will be larger, when the objects are nearer, very much the same as the lines of vision of the human eye also form a larger angle by the action of the ocular muscles, when the objects are very near the pair of eyes.

The TV camera built in accordance with this invention generally comprises a housing, within which there is mounted a pair of optical devices or lenses 12 and 13, which are colinearly arranged with a photosensitive device such as image analyzing tubes as those shown under reference numerals 16, 17 and 18 in Figure 3 ofthe drawings, which may be in number of three as shown, forming two assemblies 14 and 15, each one of said assemblies colinearly arranged with the corresponding optical assemblies 12 and 13, respectively, or which may comprise one single image analyzing tube when the signal to be transmitted is black and white.The camera built in accordance with this embodiment of the invention also comprises the two usual eye pieces 10 and 11 in order to permit the operator of the camera to look into the same through the optical assemblies 12 and 13, thus receiving a different image through each one ofthe eye pieces 10 and 11, so that said operator may also determine the manner in which the image is being generated by the camera, so as to duly control the operation thereof. The above described eye pieces, however, may be replaced by a small receiver or monitor built in the same manner to be described hereinafter for receiver 4, which may be placed behind the camera 1 to provide a stereo vision signal to the operator.

It is to be mentioned that the light sensitive elements 14 and 15 of the camera built in accordance with the present invention, may be selected from a different number of known devices, such as image analyzing tubes, charge coupled devices and the like, without thereby departing from the true scope and spirit of the invention.

Finally, the camera built in accordance with the present invention will comprise a servomechanism to control the telemetrical and angular focusing of the optical assemblies 12 and 13 and the light sensitive or image analyzing assemblies 14 and 15, which focusing action may be fully automatic, as is well known in the art, both as to the telemetry thereof and as to the stereoscopicity thereof.This servomechanisms may be manual or operated by sonar and the like, and as mentioned above, are well known in the art and it may be only necessary to adapt the same to carry out the work for which they are needed in the camera built in accordance with the present invention, whereby it is intended that the instant application will not be restricted to the use of a predetermined type of servomechanism to carry out his action, so long as said servomechanism may have the appropriate capacity to angularly move the optical assemblies 12 and 13 and image analyzing assemblies 14 and 15 in unison and at different stereoscopic angles, and at the same time may be sufficient to telemetrically control the focusing of each one of the optical assemblies 12 and 13, as is well known in the art.

In orderto produce special effect with the TV camera built in accordance with the present invention, and as shown in Figure 2 of the drawings, the camera may be provided with an additional device for producing hyper-stereoscopicity or hypostereoscopicity, for which purpose it will be necessary to space the optical assemblies 12 and 13 of the camera to a larger or lesser distance than the antropomorphic interocular distance as shown under the reference numeral 7 in Figure 2 of the drawings, for which purpose a further mechanism is provided to move, in conjunction with the focusing servomechanism described above, the two optical assemblies 12 and 13 either in the direction of the arrows 8 to produce hyper-stereoscopicity or in the direction of the arrows 9 to produce hypostereoscopicity.

It is well known that as the human eyes are fixed on objects which are at larger distances, the threedimensional effect is reduced, inasmuch as the physical spacing of the eyes is very small (only about 6 cm), whereby in the camera built in accordance with the present invention, said threedimensional effect may be considerably increased by increasing the spacing between the two optical assemblies 12 and 13, which will be moved in unison with the analyzing assemblies, thus causing an effect which is called hyper-stereoscopicity, which effect may be accomplished at the will and taste of the operator, by means of a manual control, or may be arranged in an automatic interrelationship with the telemetric servomechanism described above.

On the contrary, when the human eyes are fixed on objects located at a very close distance therefrom, the interocular spacing of about 60 mm will produce a stereo effect which is frequently too large, whereby the spacing mechanism for the optical assemblies 12 and 13 of the camera of the present invention may be provided with the capability of moving said optical assemblies 12 and 13 one to each other, in order to reduce the stereo effect, thereby to produce a less exaggerate and more pleasant stereoscopical image.

The camera built in accordance with the present invention will have twin telemeters, that is, each one of the optical assemblies 12 and 13 will always preserve equal focal distance, that is, the telemeters will be fully synchronized so as to vary the focusing distance of the two optical assemblies 12 and 13 in equal manner, so as to maintain said focusing simultaneously in the two optical assemblies. This synchronized focusing effect will be accomplished by the above mentioned servomechanism which will simultaneously actuate both optical assemblies, synchronizing their movements in unison, and the eye pieces 10 and 11 of the operator will also be binocular in order to permit said operator to appreciate the stereoscopical pair.In reality the camera built in accordance with the present invention comprises two cameras in one, one of said cameras being for the left photogram and the other one for the right photogram, but included in the same casing or apparatus illustrated with the reference numeral 1.

The angular arrangement of the two optical assemblies 12 and 13, will also be controlled by said servomechanism in function of the telemetric distance shown by the automatic or manual telemeters attached to each optical assembly, so as to synchronize all the movements, both the change in focal distance for field depth focusing, and the change in angular position to adapt the direction of the lines of vision of the two optical assemblies to a point regardless of the distance to which said point is located with respect to the optical assemblies, as already described above and in a form analogous to the natural human eye convergent strabismus.

Each optical assembly will perceive the object and the light beams will thereafter reach, if the camera is for colour television, three colour filters to thereafter pass to the image analyzing tubes 14 and 15 and then to frequency filters as is well known in the art, to thereafter be passed to the commuting device shown under number 2 in Figure 1 of the drawings.

Of course that when the camera is used for black and white images, only one single image analyzing tube will be used per each optical assembly but the actions will be exactly the same as described for colour television.

At the receiver these switched video signals will form a blockage by means of a pattern comprising a mosaic of alternated vertical straps on the image tube, all said straps being of the same width, and very fine, in order to form alternated left strap, right strap, left strap, and so forth as shown by the reference numerals 18 and 19 in Figure 5 of the drawings, which is a representation of an image screen 16 on which said vertical straps are provided by the video signals sent by the transmitter as will be described hereinbelow in connection with the electronics of the system.

The audio of the system may also be selected between monaural or stereo, but preferably the present invention utilizes stereo audio, because this will enhance the perception of the third dimension by the eyes, inasmuch as stereo vision plus stereo audio will produce a total stereo reception.

It is to be noted that the stereogram formed by alternated vertical straps will not in itself permit the observer to appreciate three-dimensional images as shown in Figure 5 of the drawings, in relation with the image screen 16 containing the vertical straps 18 and 19 for left signal and right signal respectively, inasmuch as the series of alternated stereo straps on the image screen 16 will be seen by both eyes, and in order to perceive a three-dimensional signal it is indispensible that the right eye may only see what corresponds to the right image and not what corresponds to the left image, and vice versa. In other words, each one of the human eyes must only perceive the image strap 18 or 19 which corresponds thereto and must block the contrary image.

The image signals sent by the transmitter are divided into two stereo images, which are provided in the form of alternating thin vertical straps forming an alternated mosaic on the image screen 16 as shown in 18 and 19. These alternated straps may be optically separated by means of a transparent xographic screen 17 as shown in Figure 5.

The xographic screen must be placed in front of the image tube, regardless of the fact that said image tube may be a trichromo or colour television image tube or a mono-chromatic or black and white television image tube. This xographic screen is an arrangement of semi-cylindrical lenses vertically placed in a continuous array and following a direction and having the same width as a pair of straps of the image tube, but centred for fully spanning said pair of straps as clearly shown in Figure 6 of the drawings.

In view of the interocular spacing of the human eyes each eye of the observer will look through the cylindrical lenses under a different angle, and therefore by the interposition of said semicylindrical lenses, the right eye will only ses the right image and the left eye will only see the left image, inasmuch as the light is refracted by each one of said semi-cylindrical lenses, departing from the optical axis as shown at 23 and 24 in Figure 6 of the drawings, wherein it may be seen that the pattern of the left images 18 and the pattern of right images 19 will be presented in each one of the straps 18 and 19 respectively, and being each one of said straps 18 and 19 encompassed by one single semi-cylindrical lens 20 of the screen 17, said semicylindrical lens will refract the light rays coming from the right image strap 19 towards the right as shown in 24 in Figure 5 of the drawings, whereas said semi-cylindrical lenses 20 will refract the light coming from the left strap 18 towards an angular direction shown at 23 in the drawings, thus forming two different images or light beams 23 and 24 which may be perceived by both eyes separately, namely, the left eye will receive the light rays 23, whereas the right eye will receive the light rays 24, and each one of said light rays provides a different stereoscopical image to the eyes of the observer.

The xographic screen built in accordance with the present invention may be rigid or elastic to be adjusted to the spacing which may be desired in accordance with the width of the vertical straps 18 and 19 to be transmitted, and when the reception signal is not stereoscopical, said xographical screen must be withdrawn by folding the same either in a roll form or an extended form, by means of an electrical pulse carried within one of the free regions of the band width of the video signal from the transmitter.

The stereoscopic TV system built in accordance with the present invention may be arranged such that it may comply with the international signal transmission and conduction standards, such as the NTSC, PAL and SECAM systems, and the signals may be sent by air, cable, carriers, satellites, and the like by very well known systems of transmitting television signals.

In order to more clearly understand the fundamental electronic arrangement of the system of the present invention, reference will be had in what follows to Figures 7,8,9 and 10. In accordance with said figures and particularly Figure 7 of the drawings, once the optical assemblies of the camera 1 perceive certain images different to each other, that is, right and left images, these images are translated into video signals 25 and 26, which are commuted by means of a high speed analogic switcher 2, so that said signals alternately pass in shared periods of time, containing the corresponding right and left informations.The commuting system is actually formed by a digital clock 29 operating at a frequency which is the double of the horizontal scanning frequency used nowadays, for instance, for the NTSC system, of 2 x 15,750 = 31500 Hz, a flip-flop 30 which alternately delivers a logical 1 at the outlets 34 and 35 at a fequency which is the same as the horizontal deflection (15750 Hz) for the NTSC system, and a double analogical switcher 2, having normally open electronic contacts 36 and 37 when the control signal received by said contacts is a logical zero.As it may be seen in Figure 7 of the drawings, the left video signals 26 and the right video signal 25 are controlled by the control signals sent through the outlets 34 and 35 of the flip-flop 30, respectively, and the operations of said signals is as follows: Firstly, the left video signal 26 appears at the outlet 39 of the analogical switcher 2, in the form of a wave shown at the graph Vo left in Figure 8(B) of the drawings, that is, the crest 42 of said wave appears in view of the fact that the left control signal 35 is a logical one, whereas the right control signal 34 is a logical zero, which secures the blocking of the right video signal 25 by maintaining the electronic contact 36 opened at the analogical switcher 2 whereas the electronic contact 37 of said analogical switcher is in its closed position. The right video signal 25 at this time, as shown in the graph Vo right in Figure 8(C), will not appear at the outlet 39 of the switcher 2, because at this time said signal will present the valley 44 of the wave.

Contrary to the above, when the right control signal 34 is a logical one as produced by the flip-flop 30, whereas the left control signal 35 is a logical zero, then the electronic contact 36 of the switcher 2 will be in its closed position whereas the electronic contact 37 of the switcher 2 will be in its open position, whereby it will be the right video signal 25 the one to be passed through the switcher 2, and the left video signal 26 will be stopped in view of the fact that the electronic contact 37 of the switcher 2 is in its open position, as shown by the valley 43 of the graph Vo left in Figure 8(B) and the crest 45 of the graph Vo right in Figure 8(C).

In view of the fact that the outlets of each one of the contacts of the electronic switcher 2, as shown at 40 and 41 are joined together in one single outlet 39, the result is that a commuted video signal is obtained at line 39, as shown at the graph Vo in Figure 8(D) of the drawings.

As the clock 29 will send through line 33 to the flip-flop 30 periodical pulses and its connection is direct to the inlet 33 of the flip-flop 30, periodical control pulses which are alternated between signals 35 and 34 will be obtained upon passing of one full cycle of the wave sent to the flip-flop 30 by the clock 29, under the condition that the inlets 32 and 31 of the flip-flop will maintain their logical one 1 L condition.

At the time intervals which may be regarded as odd as shown att1 in the graph corresponding to the clock in Figure 8(A) of the drawings, (wave 40), the signals to be allowed to pass through the switcher 2 are the left video signals as shown at the graph Vo left in Figure 8(B) of the drawings under reference numeral 42, that is, the signals to be allowed to pass through the switcher 2 the left video signals as shown at the graph Vo of Figure 8(D) of the drawings at 46, whereas during the even intervals of time as shown at t2 in Figure 8(A) (wave 41), the right video information as shown at 45 in Figure 8(C) and also at 47 in Figure 8(D) will be the one obtained.

The above means that, for instance, in time t, as shown in Figure 8(B) under reference character number 42 the left control signal will be a logical one whereas the right control signal as shown in Figure 8(C) at 44 will be a logical zero, whereas in the time t2, the opposite will be accomplished, namely, that the left control signal 43 is zero whereas the right control signal 45 is one, hence in the time tithe left video signal 46 will be obtained, whereas in the time t2 the right video signal 47 will be obtained, as shown in Figure 8(D).

The TV transmitting station will send the stero program signals as set of commuted video signals through the air or by cable or carrier or the like, in the same manner very well known in the prior art.

If the camera 1 of the system of the present invention is to be used for transmitting programs without the stereo image, the signals to be utilised will be the signals received by one single optical assembly of the two optical assemblies contained by camera 1, and will be sent by means of an internal control pulse as shown at 38 in Figure 7 of the drawings, which constitutes a bypass to the switcher 2 of the present invention, in order that the video signal may be sent directly to modulation in the transmitting system. In this particular instance, the clock 30 will be inhibited.

If the electronic circuitry described above in connection with Figures 7 and 8 of the drawings is used under the conditions specified, then it is necessary to effect certain modifications both to the camera and to the TV receiver because, considering the NTSC system as an example, the scanning of the beam of the stereo camera will scan through 525 lines, but contrary to the presently used systems without stereo images, vertical arrows are drawn as shown at 49 in Figure 9 of the drawings, on the video screen 48 of the receiver, instead of horizontal lines, and the frequency of stereovertical scanning is of 15,750 Hz whereas it is 60 Hz for the stereo horizontal scanning.

From the electronic point of view this is possible by using the same deflection coils of the present cameras but applying the horizontal deflecting signal to the vertical coil and the vertical deflecting signal to the horizontal coil. If the deflecting signals were applied directly on the coils of the stereo system, aii undesirable format (4 units of height by 3 units of width) would be obtained. The format of the screen of a TV stereo camera as shown in Figure 9, is the same as the format of the TV cameras used in the prior art (4 units of width by 3 units of height).In order to obtain the actual format of the screen, the horizontal deflecting coil 50 as shown in Figure 10 of the drawing receives the signal produced by the vertical amplifier 53 which must be higher at the rate of 4/3, is increased by the linear amplifier 55 which is included in the circuit, and then the signals will reach the contract 60 of the switch 54 to thereafter pass to the deflecting coil 50 as mentioned above.

Simultaneously, the vertical deflecing coil 52 will be fed from the outlet signal from the horizontal amplifier 51, which must be reduced at a rate of 3/4, which is accomplished by the voltage drop produced by the resistor 57 included in the corresponding outlet of amplifier 51. From the resistor 57, the signal reaches contact 61 of switch 56 and from there it is fed to the deflecting coil 52 as mentioned above.

When the apparatus is to be used in transmission without stereo, the operator of the camera commutes the switches 54 and 56 to the contacts 58 and 59 respectively, with which this action is removed.

The receiver apparatus will have exactly the same commuting circuit for obtaining the appropriate deflection that the circuit shown in Figure 10 for the camera, such that both be strictly synchronised both in stereo and non-stereo programs, which is accomplished by means of an electrical pulse within one of the free frequency regions of the band width in the emission.

While the above described circuitry is the one producing the best resolution for the image transmitted, it is also possible in accordance with another embodiment of the invention, to dispense with the circuitry shown in Figure 10 ofthe drawings, by having the camera and also the TV receiver of the system to provide a horizontal scanning as it is presently done in the normal TV transmission and receiving systems of the prior art.

That is, the scanning shown in Figure 9 of the drawings would not be the vertical scanning forming the lines 49, but would rather be a horizontal scanning perpendicular thereto.

In this particular instance, the commuting system will be formed by the same digital clock 29 but with the proviso that said digital clock (Figure 7) will operate to the double of the frequency of the subcarrierwhich, for instance, in the NTSC system is of 2 x 3.579545 Mhz, that is, 7.159090 Mhz and the flip-flop 30 will also deliver alternately a logical one at the outlets 34 and 35 respectively, at a frequency equal to the frequency of the subcarrier which, in the NTSC system will of 3.579545 Mhz.

This will render the operation of the high speed switcher 2 also sufficient to provide the alternating video signals at a frequency of 3.579545 Mhz in the NTSC system, but the remainder of the circuit of Figure 7 will be exactly the same, and only the modification of the deflecting coils as shown in Figure 10 of the drawings, will be avoided.The high speed which is necessary for the flip-flop, the clock and the switcher, however, render it somewhat more difficult to accomplish these goals, and the definition of power of resolution of the system would be slightly lower than those obtainable by the first above described embodiment of the invention which comprises the modifying system of the deflecting coils, although nevertheless both embodiments of the invention perform in a highly efficient manner to obtain a stereo signal which is perceived by the human eyes in a three-dimensional pattern, in view of the semi-cylindrical lenses interposed between the surface of the video screen of the receiver, and the eyes of the user, as fully described above.

As is well known in the transmission of TV images, it is possible that, in certain areas the reception may not be completely accurate and therefore the pattern of adjustment of the image at the screen of the image tube and the convergence of the image may not be sufficiently accurate to coincide with the positions necessary for the refraction of the light by means of the semicylindrical lenses of the xographic screen 17.This problem, however, is practically absent in cable transmission of TV signals, but is quite frequent in certain regions where the TV transmission is effected through air carriers and satellites, etc, whereby it is always convenient to provide both the camera 1 and the receiver 4 of the system of the present invention with an automatic pattern and convergence adjustment control, as well as with an automatic voltage regulator and, in order to align the bands containing left and right images with the semicylindrical lenses, it is also highly convenient to provide in the receiver 4 of the system an automatic of manual horizontal position control, preferably provided with a fine tuner.

This will secure that the pattern received at the image tube will be perfectly adjusted as to length and width and that the convergence of the image, particularly in colour images, will be accurate, thereby accomplishing the goal of obtaining a full three-dimensional image perception by the user of the TV receiver set. Also, the control for adjusting the horizontal position of the image, may be regulated by the user in order to locate the vertical bands containing left and right images precisely in the position shown in Figure 6 of the drawings, in order to obtain the maximum resolution and stereoscopicity of the image in combination with the semicylindrical lenses of the xographic screen.

Claims

1. A stereoscopic television system which comprises, in combination, a stereoscopic camera means having two separate parallax-producing optical means, servocontrol means for focusing said optical means both for parallax and depth in order to produce two separate stereo images, light sensitive means coupled to each one of said optical means to convert said stereo images into corresponding video signals; high speed signal commuter means to produce alternated video signals from said video signals produced by said light sensitive means; signal transmitter means for transmitting said alternated video signals produced by said signal commuter means; signal receiver means for reception of said transmitted alternated signals, said signal receiver means comprising image tube means having a luminescent screen, signal deflecing coil means to format said received alternated signals as a pattern of alternated vertical straps on the luminescent screen of said image tube means; and xog raphic screen means superposed to said luminescent screen and comprising a plurality of vertical semicylindrical lenses to refract in opposite angular directions the alternated straps containing the information of each one of the alternated received signals, so as to produce perception of a three-dimensional image in an observer.

2. A stereoscopic television system according to claim 1 wherein said parallax-producing optical means comprise a pair of optical assemblies mounted at a distance from each other such that said distance be equivalent to the antropomorphic interocular spacing.

3. A stereoscopic television system according to claim 2 wherein said pair of optical assemblies include a spacer mechanism to laterally move said optical assemblies toward and away from each other, in order to produce a hypo- or hyperstereoscopicity effect.

4. A stereoscopic television system according to any one of claims 1 to 3 wherein said servocontrol means include a pair of synchronised automatic telemetric means for focusing each one of said optical means and automatic angular actuator means synchronised with said telemetric means for angularly moving said optical means so as to provide the parallax between said two optical means which corresponds to the telemetric focusing thereof.

5. A stereoscopic television system according to claim 4, wherein said light sensitive means are image analysing tubes colinearly arranged with said optical means.

6. A stereoscopic television system according to claim 4, wherein said light sensitive means are charge couple devices colinearly arranged with said optical means.

7. A stereoscopic television system according to any one of claims 1 to 6, wherein said high speed signal commuter means comprises high speed electronic switcher means, clock means to control the timing of said switcher means, and flip-flop circuit means to receive the time signal from said clock signals to be applied to said switcher means, said switcher means having two electronic contacts which are open when the signal received from said flip-flop is a logical 0 and are closed when said signal is a logical one.

8. A stereoscopic television system according to claim 7 wherein said image tube has means to effect a vertical scanning of said luminescent screen and said deflecting coil means comprises a vertical deflecting coil and a horizontal deflecting coil, resistor means connected to said vertical deflecting coil to reduce the distance of vertical scan by 3/4, and linear amplifier means connected to said horizontal deflecting coil to increase the distance of vertical scan by 4/3, so as to provide the necessary vertical to horizontal 3:4 image format on said luminescent screen.

9. A stereoscopic television system according to claim 7 wherein said image tube has means to effect a horizontal scanning of said luminescent screen and said deflecting coil means comprises unmodified vertical and horizontal deflecting coils for producing a 3 units vertical scan and a 4 units horizontal scan, so as to provide the necessary vertical to horizontal 3:4 image format on said luminescent screen.

10. A sterecscopictelevision system according to any one of claims 1 to 9 wherein said stereoscopic camera means and said receiver means each comprise automatic pattern and convergence adjustment means to secure accurate 3:4 image pattern and colour convergence in the luminescent screen.

11. A stereoscopic television system according to claim 10 wherein said receiver means comprises automatic or manual horizontal image position control means for securing alignment of a pair of said alternated straps with each one of said semicylindrical lenses of the xographic screen means.

12. A stereoscopic television system according to claim 1 wherein said light sensitive means are provided in number of three for each optical means for colour television.

13. A stereoscopic television system according to claim 1 wherein said light sensitive means are provided in number of one for each optical means for black and white television.

14. A stereoscopic television system according to claim 7 wherein said switcher means comprises a bypass electronic contact and means to actuate said bypass electronic contact and to open said two electronic contacts of the switcher means, in order to permit transmission of black and white television images.