Stereoscopic Color Television System With Lenticular Screen

This invention relates to a stereoscopic color television system. The known stereoscopic color television sytem include a type which comprises two picture tubes combined with polarizing glasses, a type using a lenticular lens assembly and a type based on application of laser rays. However, none of those known stereoscopic color television systems are as suitable as expected. For example, in known systems using a lenticular lens assembly true color stereoscopic pictures can be achieved at best at very limited viewing angles.

It is accordingly an object of this invention to provide a stereoscopic color television system based on the NTSC system.

Another object of the invention is to provide a stereoscopic color television receiving system adapted also to receive the existing broadcast color television and monochrome television.

Still another object of the invention is to provide a picture tube adapted suitably for reproduction of a stereoscopic color image.

A furthr object of this invention is to provide a three-dimensional color television system which enables true color stereoscopic viewing from any position without the necessity of using any viewing from any position without the necessity of using any viewing aids such as polarized glasses or special optical spectacles and is compatible with existing monochrome and color television systems.

According to an aspect of the invention, there is provided a stereoscopic color television transmission method comprising the steps of: photographing an object by M color television cameras provided with color signal outputs and horizontally arranged at an equal interval; generating a horizontal synchronization signal, a vertical synchronization signal for each field, a stereoscopic synchronization signal for every Mx2 fields or M frames and a color subcarrier signal; switching the operation of said M color television cameras successively in response to the horizontal synchronization signal, vertical synchronization signal, stereoscopic synchronization signal and color subcarrier signal per period of said color subcarrier signal, while changing for each field the order in which the operation of said M color television cameras is switched over during every M periods of the color subcarrier signal; and sending forth output signals from said M color television cameras together with the horizontal synchronization signal, vertical synchronization signal, stereoscopic synchronization signal and color subcarrier signal.

According to another aspect of this invention there is provided a color television receiver apparatus comprising a cathode ray tube including a faceplate, a shadow mask, a lenticular lens assembly which is disposed between the faceplate and shadow mask, and is formed of lenticular lenses horizontally arranged with an equal width to the horizontal pitch of apertures of the shadow mask and eash adapted to display the effect of a convex lens only in a horizontal direction, and a plurality of sets of three color phosphor stripes formed with an equal width to the vertical pitch of the apertures of the shadow mask on the focal plane of the lenticular lens assembly which faces the shadow mark, and M horizontally arranged groups of electron guns each formed of three vertically arranged electron guns; means for demodulating, upon the receipt of broadcast signals, a horizontal synchronization signal, vertical synchronization signal, stereoscopic synchronization signal, color subcarrier signal and three video signals including color information; means for coupling the three video signals to the corresponding electron guns of the M groups of electron guns included in the cathode ray tube; and means for succesively switching the operation of the M groups of electron guns in response to the horizontal synchronization signal, vertical synchronization signal, stereoscopic synchronization signal and color subcarrier signal.

According to still another aspect of this invention there is provided a stereoscopic color television receiver apparatus comprising a cathode ray tube including a faceplate, shadow mask, lenticular lens assembly which is disposed between the faceplate and shadow mask, and is formed of lenticular lenses horizontally arranged with an equal width to the horizontal pitch of apertures of the shadow mask and each adapted to display the effect of a convex lens only on a horizontal direction and a plurality of sets of three color phosphor stripes each formed with an equal width to the vertical pitch of apertures of the shadow mask on the focal plane of the lenticular lens assembly which faces the shadow mask, and three vertically arranged electron guns; means for demodulating, upon receipt of broadcast signals, a horizontal synchronization signal, vertical synchronization signal, stereoscopic signal, color subcarrier signal and three video signals including color information; means for coupling the three video signals to the corresponding electron guns included in the cathode ray tube; and means for horizontally shifting electron beams emitted from the three electron guns in response to the horizontal synchronization signal, vertical synchronization signal, stereoscopic synchronization signal and color subcarrier signal.

FIG. 1 is a schematic oblique view of a stereoscopic color television picture tube embodying the invention;

FIGS. 2 and 3 are diagrams for explaining the operation of the stereoscopic color television picture tube;

FIG. 4 shows the relationship of a lenticular lens assembly and a shadow mask;

FIG. 5 is a block diagram of a stereoscopic color television transmission system embodying the invention;

FIG. 6 indicates the section for switching the color television cameras of FIG. 5;

FIG. 7 shows the order in which the operation of the color television cameras in switched over for each field;

FIG. 8 shows the waveforms of video signals issued during three picture frames by the stereoscopic color television system of the invention;

FIGS. 9A and 9B show a block diagram of a stereoscopic color television receiver according to an embodiment of the invention;

FIG. 10 shows a stereoscopic color television receiver according to another embodiment of the invention;

FIG. 11 shows the arrangement of a ring counter for shifting electron beams used with the receiver of FIG. 10;

FIG. 12 schematically indicates a lateral shift device used with the receiver of FIG. 10;

FIG. 13 shows a stereoscopic color television receiver according to still another embodiment of the invention;

FIG. 14 shows the arrangement of a ring counter section of FIG. 13; and

FIGS. 15 and 16 illustrate the operation of the color television receiver of FIG. 13.

Prior to description of a stereoscopic color television transmission system embodying this invention, there will now be explained the principle by which a stereoscopic color image is reproduced by reference to FIGS. 1 to 4 showing a cathode ray tube for the stereoscopic color television.

Referring to FIG. 1, the stereoscopic color picture tube of this invention includes a lenticular lens assembly LL positioned between a cathode ray tube faceplate FP and a shadow mask SM which may be of the same type as that used in the ordinary color television picture tube. The respective horizontally arranged lenticular lenses of the lenticuular lens assembly LL extend in the vertical direction of the faceplate FP and are each formed with an equal width to the horizontal pitch W of the holes of the shadow mask SM. Namely, in accordance with this invention, the lenticular lenses of the lenticular lens assembly LL are so arranged as to present the effect of a convex lens only in the lateral direction of the faceplate FP.

The focal plane FL of the lenticular lens assembly LL which faces the shadow mask SM is made smooth. A large number of red, green and blue phosphor stripes R, G, B are horizontally formed, as shown in FIG. 4, on the smooth focal plane FL of the lenticular lens assembly LL. The respective sets of red, green and blue phosphor stripes R, G, B are arranged with an equal width to the longitudinal pitch U of the holes of the shadow mask SM.

As shown in FIG. 1, three electron gun groups .alpha.g, .beta.g, .theta.g each formed of three vertically arranged electron guns used for emission of red, green and blue lights respectively are set in a lateral direction. The three electron gun groups are so arranged that when electron beams emitted from the electron guns pass through a given hole of the shadow mask SM on the phosphor screen, then those portions of one set of red, green and blue phosphor stripes which correspond to the given hole and lie immediately under one lenticular lens of the lenticular lens assembly LL emit three color lights indicated by .alpha.R, .alpha.G, .alpha.B; .beta.R, .beta.G, .beta.B; and .theta.R, .theta.G, .theta.B according to the intensity of electron beams emitted from the electron guns.

In this invention, the operation of the electron gun groups .alpha.g, .beta.g, .theta.g is switched in turn at a rate equal to the frequency of a color synchronization subcarrier signal.

FIG. 2 shows the manner in which an image reproduced on the color television picture tube of FIG. 1 is watched by both eyes of an observer. Where the observer occupies a position shown in FIG. 2, the left and right eyes of the observer can see images reproduced by, for example, electron gun groups .beta.g and .theta.g due to the lateral lens action of the lenticular lens assembly LL, but cannot recognize an image reproduced by the electron gun group .alpha.g. A bright spot under each lenticular lens is spread to the full width W of the lens due to its property. FIG. 3 presents the manner in which the observer's left eye LE watches an image reproduced by the electron gun group .beta.g. Depending on the position occupied by an observer, images reproduced by the electron gun groups (.alpha.g+.beta.g), (.alpha.g+.theta.g), or (.beta.g+.theta.g) can be observed, thereby allowing true color stereoscopic viewing from a plurality of positions. As mentioned above, the observer's left eye LE and right eye RE watch different images. Obviously, therefore, these images, if stereoscopically picked up, admit of a stereoscopic observation.

FIG. 5 is a block diagram of a stereoscopic color television transmission system embodying this invention. This system is little different from the ordinary color television transmission system, except for the sections S1, S2 enclosed in broken lines. Red, blue and green video signals from the color television camera section S2 are supplied to a matrix circuit Mat through gamma correction circuits R.gamma., G.gamma., B.gamma. to provide a luminance signal Y and color video signals I, Q. The Q signal is conducted to a 0.5 MHz bandpass amplifier Qa. The I signal is applied to a 1.5 MHz bandpass amplifier Ia through a delay circuit Id1. The Y signal is applied to another delay circuit Yd1.

A color subcarrier of 3.58 MHz generated by an oscillator O has its phase shifted -57.degree. by a first phase shifter P1, and further shifted -90.degree. by a second phase shifter P2. An output from the second phase shifter P2 is suppressed-carrier amplitude-modulated by the Q signal from the bandpass amplifier Qa in a balanced modulator Qmd. An output from the first phase shifter P1 is suppressed-carrier amplitude-modulated by the I signal from the bandpass amplifier Ia in a balanced modulator Imd.

The 3.58 MHz color subcarrier is applied to a color synchronization burst generator Bg and synchronization signal generator SY to provide a horizontal synchronization signal HSP, vertical synchronization signal VSP and stereoscopic synchronization signal SSP. Outputs from the delay circuit Yd1, modulators Imd, Qmd, color synchronization burst generator Bg and synchronization signal generator SY are delivered to an adder Add to provide a colorplexed video signal. The colorplexed video signal is applied to an amplitude modulator Amd through a low pass filter LPF. Voices picked up by a microphone Mic are amplified by an amplifier Sa. A sound carrier is frequency modulated with the output signal of the amplifier Sa in a frequency modulator Fmd. Outputs from the amplitude modulator Amd and frequency modulator Fmd are coupled to a transmission antenna T.Ant. A transmitted signal has a frequency band of about 6 MHz as in the ordinary television broadcasting.

The color television camera section S2 comprises, for example, three color television cameras .alpha.c, .beta.c, .theta.c equidistantly spaced in a horizontal direction as shown in FIG. 5.

As far as the stereoscopic photographing of an object is concerned, the interspace between the cameras .alpha.c, .beta.c, .theta.c has no direct relationship with a distance between both eyes of an observer. Therefore, the interspace of the cameras .alpha.c, .beta.c, .theta.c may be suitably chosen. The camera .alpha.c comprises red, green and blue pickup tubes .alpha.Ri, .alpha.Gi, .alpha.Bi; the camera .beta.c comprises red, green and blue pickup tubes .beta.Ri, .beta.Gi, .beta.Bi; and the camera .theta.c comprises red, green and blue pickup tubes .theta.Ri, .theta.Gi, .theta.Bi.

The cathodes of the pickup tubes of the respective cameras .alpha.c, .beta.c, .theta.c are jointly connected to the corresponding output terminals of the camera switching section S1. The input terminals of the camera switching section S1 are supplied with 3.58 MHz color synchronization pulses from the oscillator O, horizontal synchronization pulses HSP and vertical synchronization pulses VSP and stereoscopic synchronization pulses SSP emitted for every three picture frames (or 6 fields) from the synchronization signal generator SY, thereby causing the cameras .alpha.c, .beta.c, .theta.c to be successively switched per period of the color synchronization pulses.

FIG. 6 illustrates the arrangement of the camera switching section S1 which is formed of a ring counter comprising two TTL logic integrated circuits SN7496N manufactured by Texas Instrument Incorporated. Negative horizontal synchronization pulses HSP are supplied to a differentiation circuit formed of a capacitor C1 and resistor R1. A negative spike pulse generated by the differentiation circuit is applied to the terminal T16 of a first ring counter RCA through a diode D1. A positive spike pulse produced by the differentiation circuit is applied to the terminal T8 of the first ring counter RCA through a diode D2. The terminal T16 is connected to the clear terminals Cr of flip-flop circuits .alpha.FF, .beta.FF, .theta.FF, all of which, therefore, are cleared in response to the negative transition of the horizontal synchronization pulses. As the result, the output terminals Q of all the flip-flop circuits are set at a zero potential.

The terminal T8 of the first ring counter RCA is connected to the preset terminals Pr of the flip-flop circuits .alpha.FF, .beta.FF, .theta.FF through NAND gates. Terminals T2, T3 and T4 are coupled to the preset terminals Pr of the flip-flop circuits .alpha.FF, .beta.FF and .theta.FF through the NAND gates, respectively. Each flip-flop circuit is preset when the positive spike pulse is applied to the terminal T8 and the corresponding one of the terminals T2, T3 and T4 is at a positive level. When, therefore, the terminal T2 connected to the terminal T115 of a second ring counter RCB is at a positive potential, then the flip-flop circuit .alpha.FF is preset. Accordingly, the output terminal Q of the flip-flop circuit .alpha.FF is rendered positive to activate a transistor TR.alpha. connected to the terminal T15, thereby causing the cathodes of the pickup tubes of the color television camera .alpha.c to be grounded to operate the camera .alpha.c. At this time, only the camera .alpha.c sends forth video signals.

3.58 MHz color synchronization pulses CSP are applied to the terminal T1 coupled to the clock terminals CK of the flip-flop circuits .alpha.FF, .beta.FF, .theta.FF. The outputs Q of the flip-flop circuits .alpha.FF, .beta.FF, .theta.FF are successively rendered positive by the color synchronization pulses CSP. Namely, if a color synchronization pulse is applied to the terminal T1 when the output Q of the flip-flop circuit .alpha.FF is positive, then the output Q of the flip-flop circuit .alpha.FF is set to the zero potential and the output of the flip-flop circuit .beta.FF is set to the positive level. At this time, the transistor TR.beta. connected to the terminal T14 is rendered conductive and the video signals from the camera .beta.c are sent forth. Upon receipt of the next color synchronization pulse, only the terminal T13 is rendered positive to activate the transistor TR.theta.. As a result the camera .theta.c sends forth video signals. When the succeeding color synchronization pulse CSP is delivered to the terminal T1, then the output terminal Q of the flip-flop circuit .alpha.FF is set to the positive level to render the transistor TR.alpha. conductive. Consequently, the camera .alpha.c is put into operation and sends forth video signals.

Thus, the operation of the color television cameras .alpha.c, .beta.c, .theta.c is switched over in turn per period of a color synchronization pulse CSP during every period of horizontal scanning. Periodically changing the order of camera scanning operation, as is explained in more detail below, minimizes the loss of resolution and flicker which could result from a non-alternated scanning order. Accordingly, when each succeeding horizontal synchronization pulse is supplied, all the flip-flop circuits are cleared. Thereafter, the operation of the color television cameras .alpha.c, .beta.c, .theta.c is changed over successively in the order mentioned upon receipt of color synchronization pulses CSP during the horizontal scanning period of the first field (odd field).

The determination of which camera will first operate at the beginning of each horizontal scanning panel in the above-mentioned changed-over operation of the color television cameras .alpha.c, .beta.c, .theta.c is controlled by the second ring counter RCB connected to receive stereoscopic synchronization signal SSP and vertical synchronization signal VSP. Namely, upon receipt of stereoscopic synchronization signal SSP produced for every six fields (or three frames) in synchronism with a vertical synchronization pulse VSP, flip-flop circuits FF1, FF2, FF3 included in the second ring counter RCB are cleared like the flip-flop circuits .alpha.FF, .beta.FF, .theta.FF included in the first ring counter RCA. Later, the flip-flop circuit FF1 alone is preset since terminal T102 is connected to a positive DC power supply Vcc and the output terminal Q thereof is set to the positive level. Since the terminal T115 connected to the output terminal Q of the flip-flop circuit FF1 is also connected to the terminal T2 of the first ring counter RCA, the flip-flop circuit .alpha.FF alone is preset as previously described. In the first field immediately following the issue of a stereoscopic synchronization pulse SSP, the operation of the color television cameras .alpha.c, .beta.c, .theta.c is changed over successively in the order mentioned. The outputs Q of the flip-flop circuits FF1, FF2, FF3 of the second ring counter RCB are successively set to the positive level, each time a vertical synchronization pulse VSP is supplied to the terminal 101. In the the second field following the first field, the output Q of the flip-flop circuit FF2 alone is set to the positive level. Since the terminal T3 is rendered positive which is connected to the terminal T114 connected with the output Q of the flip-flop circuit FF2, the flip-flop circuit .beta.FF alone of the first ring counter RCA is preset. Namely, in the second field, the operation of the color television cameras .beta.c, .theta.c, .alpha.c begins with camera Bc and is changed over in the order mentioned for each horizontal scanning period.

In the third field, the output terminal Q of the flip-flop circuit FF3 alone is set to the positive level. In the third field, therefore, the operation of the color television cameras .theta.c, .alpha.c, .beta.c begins with camera .theta.c and is changed over successively in the order mentioned. The operation of the color television cameras is switched over in the order of .alpha.c, .beta.c, .theta.c in the fourth field, in the order of .beta.c, .theta.c, .alpha.c in the fifth field and in the order of .theta.c, .alpha.c, .beta.c in the sixth field. In the seventh and succeeding fields, the above-mentioned switching of the operation of the color television cameras is repeated by the same process as described above due to an interlaced scanning system and the issue of a stereoscopic synchronization signal for every six fields. FIG. 7 shows the order in which the operation of the color television cameras is changed over in different orders throughout the first to the sixth field.

As apparent from the foregoing description, where three color television cameras are used, each camera sends forth one picture frame in one-tenth of a second. It is further apparent from the foregoing description that the disclosed sequencing of the starting order of switching the three cameras enhences image resolution or definition which otherwise would have been reduced over normal resolution or definition by the multiplexing of three picture signals. Where M color television cameras are provided, a stereoscopic synchronization signal is issued for every Mx2 fields. In this case, each camera generates one picture frame in a time of M/30 sec.

FIG. 8 shows the waveforms of video signals issued during three picture frames by the stereoscopic color television system of this invention. Bst denotes a burst signal and Eqp shows an equalization pulse. A stereoscopic synchronization signal is overlapped on a vertical synchronization signal VSP at the rate of once for every three frames.

FIG. 9 represents the arrangement of a color television receiving device provided with a cathode ray tube including nine electron guns as shown in FIG. 1. This receiving device is little different from the ordinary color television receiving device except for the sections S1, S2 enclosed in broken lines. Tun denotes a tuner; IFa an intermediate frequency amplifier; Pdct a video signal detector; Pa1 a first video amplifier; Pa2 a second video amplifier for amplifying a Y signal; Yd1 a delay circuit for delaying the Y signal; Pa3 a third video amplifier; Ca a bandpass amplifier; Bst a burst gate; APC an automatic phase control circuit; and XZdm a demodulator for demodulating the signals X, Z by a color subcarrier issued from the 3.58 MHz oscillator OSC. Color video signals R-Y, G-Y, B-Y are respectively synthesized by a matrix circuit Mat. SY denotes a synchronization signal separator for separating a horizontal synchronization signal HSP, vertical synchronization signal VSP and stereoscopic synchronization signal SSP form an output signal from the first video amplifier Pa1, Df1 shows horizontal and vertical deflection circuits; Ht a high voltage power source for the anode And of the picture tube; Conv a convergence device; Vdct a sound detection circuit; Vif an intermediate frequency amplifier; FMdct an FM detector; Va an audio amplifier; and SP a loudspeaker.

The ring counter section RC of FIG. 9 has the same arrangement as that of FIG. 6. Namely, the ring counter section RC causes the operation of three groups .theta.g, .beta.g, .alpha.g of electron guns of the picture tube which are arranged in the same manner as in FIG. 1 to be switched over, each time operation of the corresponding three color television cameras is changed over. A demodulated Y signal is supplied to the cathode of that group of electron guns which is operated. Color video signals R-Y, G-Y, B-Y are applied to the grids of the corresponding electron guns of the respective groups. Since a stereoscopic color picture picked up by the color television cameras .alpha.c, .beta.c, .theta.c is reproduced on a picture tube, an observer can recognize a stereoscopic color picture by the action of a lenticular lens assembly.

FIG. 10 indicates the arrangement of a stereoscopic color television receiving device according to another embodiment of this invention. This embodiment comprises only one group of vertically arranged red, blue and green electron guns and an electromagnetic lateral shifting device Latsh responsive to a ring counter RC for shifting electron beams emitted from electron guns in a horizontal direction in synchronism with the operation of the color television cameras. With the ring counter section S1 of FIG. 10, the terminal T15 of a first ring counter RCA is connected to the base of a transistor TR.alpha. and the terminal T13 thereof is connected to the base of a transistor TR.theta. as shown in FIG. 11. The terminal T14 of the first ring counter RCA is put out of use in this embodiment. The collectors of the transistors TR.alpha., TR.theta. are connected, as shown in FIG. 12, to the terminals .theta.L, .alpha.L of the lateral shifting device Latsh. When the terminal T15 of the first ring counter RCA is rendered positive, namely, when the color television camera .alpha.c is operated, then current flows through coils lying between the terminals +B, .alpha.L of the lateral shifting device Latsh, causing electron beams emitted from the electron gun group to be shifted in the right direction of FIG. 12. When the terminal T13 of the first ring counter RCA is rendered positive, then current flows through coils lying between the terminals +B, .theta.L of the lateral shifting device Latsh, causing electron beams emitted from the electron gun group to be shifted in the left direction of FIG. 12. When the terminal T14 of the first ring counter RCA is rendered positive, then the lateral shifting device Latsh causes electron beams emitted from the electron gun group to move straight forward without deflection.

FIG. 13 represents a stereoscopic color television receiving device according to still another embodiment of this invention. This embodiment comprises control electrodes .theta.p, .alpha.p for effecting the horizontal shifting of electron beams emitted from the vertically arranged electron guns and, in place of a shadow mask, a meshy focusing grid Gn for focusing electron beams.

The meshy focusing grid Gn is formed of 400 to 800 substantially square meshes in the horizontal direction and is normally impressed with a voltage about 15 kv lower than that of the anode And of the picture tube. When passing through the meshes, electron beams emitted from the electron gun group are focused to impinge on a phosphor screen.

FIG. 14 shows the arrangement of a ring counter section RC used with the embodiment of FIG. 13. The terminal T15 of a first ring counter RCA is connected to the base of a transistor TR.alpha.1 whose collector is connected to the base of a transistor TR.alpha.2. The terminal T13 of the first ring counter RCA is connected to the base of a transistor TR.theta.1 whose collector is connected to the base of a transistor TR.theta.2. The collectors of the transistors TR.alpha.2, TR.theta.2 are connected to the control electrodes .alpha.p, .theta.p respectively and the emitters of transistors TR.alpha.2, TR.theta.2 are jointly connected to the +B power supply terminal.

When the terminal T15 of the first ring counter RCA becomes positive, then the transistors TR.alpha.1, TR.alpha.2 are rendered conducting, and the control electrode .alpha.p is impressed with +B voltage, thereby causing electron beams emitted from the electron gun group to be shifted in the left direction. When the terminal T13 of the first ring counter RCA is rendered positive, then the transistors TR.theta.1, TR.theta.2 are rendered conducting to connect the control electrode .theta.p to the +B power supply terminal, causing the electron beams emitted from the electron gun group to be shifted in the right direction. When the terminal T14 of the first ring counter RCA is made positive, then neither of the control electrodes .alpha.p, .theta.p is connected to the +B power supply terminal, causing the electron beams emitted from the electron gun group to run straight between the control electrodes .alpha.p, .theta.p.

FIG. 15 illustrates the operation of a picture tube used with the embodiment of FIG. 13. Electron beam emitted from the top blue electron gun Bg is focused by the focusing grid Gn to land on a blue stripe occupying the lowest position in one set of phosphor stripes formed on a phosphor plane Fl. Electron beam emitted from the central green electron gun Gg lands on a green stripe occupying the central position of said one set of phosphor stripes. Electron beam emitted from the bottom red electron gun Rg land on a red stripe occupying the top position of said one set of phosphor stripes. FIG. 16 shows the process by which a pair of control electrodes .alpha.p, .theta.p enables a single group of electron guns to have the same function as three groups of electron guns. As apparent from FIGS. 15 and 16, a color television picture tube used with the embodiment of FIG. 13 comprises a plurality of sets of red, green and blue phosphor stripes each arranged with substantially the same equal width as the vertical width of the respective meshes of the meshy focusing grid Gn. The respective lenses of the lenticular lens assembly L are each formed with substantially the same width as the horizontal width of the respective meshes of the focusing grid Gn.

It will be seen from the foregoing description that with a stereoscopic color television system of this invention, ten frames of pictures ae reproduced per second, with the unavoidable accompaniment of some flickers. Therefore, phosphors used with the picture tube of this invention are preferred to be a type having some degree of persistence. With a shadow mask type picture tube, a reproduced picture becomes slightly dark, making it necessary to increase the anode voltage of the picture tube. If the above described meshy focusing grid is employed and/or if a color synchronization subcarrier is chosen to have a frequency of about 10 MHz, then the above-mentioned flickers will be effectively eliminated.

When the broadcast ordinary color or monochrome television is received by the above-mentioned stereoscopic television receiving system of this invention, then three identical pictures are reproduced, preventng an observer from recognizing a stereoscopic picture, and simply reproducing the same picture as is obtained from the ordinary television receiving device. The stereoscoping television system of the invention, if used in a closed circuit, will display a more prominent effect.