US2989583A - Electron beam control system for vertical strip color tube - Google Patents

Description

R. D. THOMPSON June 20, 1961 ELECTRON BEAM CONTROL SYSTEM FOR VERTICAL STRIP COLOR TUBE Filed OC'L. 20. 1954 4 Sheets-Sheet 1 June 20, 1961 R. D. THOMPSON ELECTRON BEAM CONTROL SYSTEM FCR VERTICAL STRIP COLOR TUBE Filed Oct. 20, 1954 54M Jef/U INVENTOR. oaf T10/wia# BY fro/Mfr June 20, 1961 R. D. THOMPSON ELECTRON BEAM CONTROL SYSTEM FOR VERTICAL STRIP COLOR TUBE Filed Oct. 20, 1954 4 Sheets-Sheet 5 INVENTOR R065? 0. Z100/#50N June 20, 1961 R. D. THoMPscN 2,989,583

ELECTRON BEAM CONTROL sYsTEM ROR VERTICAL STRIP COLOR TUBE Filed Oct. 20, 1954 4 Sheets-Sheet 4 INVENTOR. R065@ 7. ZoMso/v United States Patent 4O ELEc'moN BEAM coisrRoL SYSTEM FOR VERTICAL STRIP COLOR TUBE Roger D. Thompson, Princeton, NJ., assignor to Radio Corporation of America, a corporation of Delaware Filed Oct. 20, 1954, Ser. No. 463,380 '13 Claims. (Cl. 178' .'4)

This invention relates to color television and more particularly to methods and arrangements for the reproduction of images in substantially their natural color.

It has been previously proposed to reproduce an image in color by causing a beam of electrons to repeatedly impinge upon different color light producing elements. 'Ihe beam of electrons being sequentially intensity modulated with signals representative of each of the different light colors as it is deflected over the different color light producing elements. The periods or intervals of beam modulation with a particular signal, must correspond to particular impinging intervals, i.e., periods during which the beam impinges upon a particular color light producing element. Such a system requires accurate controlling of the electron beam intensity modulation with respect to beam position, such that the interval during which a color light producing element of a particular color is being excited repeatedly will coincide with the interval during which like color signals modulate the electron beam.

'Ihe presentinvention in its more general form applies to a color television receiver wherein an electron beam repeatedly impinges upon various light producing elements on a target electrode, and is a method and apparatus for applying to the electron beam during particulark intervals, color signals which are representative of colors which coincide with the colors produced by the light producing elements on which the beam repeatedly impinges. The system Iutilizes certain signal generating elements placed on the target electrode, which are so positioned as to generate a control signal indicative of the position of the electron beam with respect to the light producing elements. The control signal generated by the signal generating elements is not only used to maintain the correct relationship between the time interval during which the electron beam impinges on a particular lightproducing element, and the time interval din-ing whichv the electron beam is modulated by a particular color signal by sequentially switching the appropriate color channels on to the electron beam control means but the control signal is also employed to control the sequence rate which is subject to change if non-linear Vdeiection s experienced.

An object of this invention is to provide an improved color television image reproducing system.

Another object of this invention is to provide an improved electron beam controlling system by means of which an electron beam may be caused to excite a series of light producing Velements according to the reception of video signals representing the colors reproduced respectively by said elements.

A further object of the invention is to provide a color television image reproducing system in Which'a multicolor ikinescope is used, having a vertically arranged striplike light-producing element target in which is incorporated facilities for generating control signals which may be utilized to control the intervals of intensity modulation of the electron beam with respect to the intervals during which different light colors are produced by the kinescope.

Other and incidential objects of this Ainvention will be apparent to those skilled in the art from reading the -following specification and on inspection of the accompanying drawings in which:

FIGURE 1l shows a block diagrammatic representation of one Aform of the invention.

2,989,583 PatentedV June 20, 1961 FIGURES 2A and 2B show views of a form of a target electrode to be used in the kinescope of a system of the invention shown in FIGURE 1.

FIGURES 3a, Sband 3c show various curves and diagrammatic representations to be used in the explanation of the invention.

FIGURE 4 shows a block diagrammatic representation of another form of the invention.

FIGURE 5 shows one form of a variable phase shifter which may be used in the diagrammatic representation of FIGURE 1.

FIGURE 6 shows one form of gate circuit which may be used in the diagrammatic representation of FIGURES 1 and 4.

FIGURE 7 shows one form of a photocell voltage control circuit which may be used in the diagrammatic representations of FIGURES 1 and 4.

Referring now to FIGURE 1 there is shown a television receiver 10 which is utilized for receiving a television signal and forming therefrom 3 image component color signals. The color signals being a green signal, a blue signal, and a red signal. A television receiver for deriving such color signals from a received color television signal is shown and described in Radio Television News May 1954, in an article entitled Fundamentals of Color Television by Milton S. Kiver. 'I'he color signals green, blue and red are applied respectively to gate circuits 12, 14 and 16. A further gate circuit 18 is provided to gate a substantially unvarying voltage from a voltage source 20. The gated color signals from the gate circuits 12, 14, 16 and the gated unvarying voltagev from the gate circuit 18 are combined and applied to a cathode 21 of an image reproducing tube 22. The control or gating of the circuits 12, 14, 16 and 18 is effected by gating signals from variable phase shifter circuits 24, 26, 28 and 30. A control signal is generated within the image reproducing tube 22. The detailed manner which the control signal is generated will be later explained; however, generally, the control signal results from electron beam energy exciting signal generating elements within the image lreproducing tube 22. The light control signals emitted from the signal generating elements are` selected from otherlight signals by a wave length selec-y tive light lter 37, and converted into electrical control signals at the photoelectric cell 36 which serves as 4a sensing means.

.It is to be understood that in other forms of the invention other methods than light control signal generating elements may be used, for example, electron emissive elements, or electron conductive elements.

The control signal is separated into a low pass control signal by a low pass filter 34, and a band pass control signal by a bandpass iilter 38. The bandpass control signal is applied to the variable phase Shifters 24, 26, 28 and 30 to be shifted in phase yand formed into gating signals to control the operating and closing of the gate circuits 12, 14, 16 and 1S. The low pass control signal is amplilied by a D.C. amplifier 32 and applied to the variable phase Shifters 24, 26, 28 and 30 to vary the phase shift effected by the respective phase Shifters. The low pass control signal thus acts as a phase shift control signal to vary the degree of phase shift of the gating signals.

The low pass control signal, passing through the low pass iilter 34 is also utilized as a servo control lfor the voltage supply to the photoelectric cell 36 to provide control of phototube gain. The signal is fed to a peak detector 40 and then amplified in a D.C. amplifier 42, after y which it is applied to a phototube voltage control circuit 44 to vary the voltage applied at the photoelectric cell from a voltage source 46 in accordance with the amplitude of -the peak amplitude of the low pass control signal. Since this rectification is of the peak type, re-

will be proportional to the phototube output produced during the initial portion of each horizontal scan, in which sampling has not yet begun. The signal so produced -thus provides a reference signal to set the photocell voltage.

The image reproducing tube 22 is also provided with deection coils 23 to be utilized to cause an electron beam in tube 22 to scan a raster pattern.

Before explaining the operation of the system shown i n FIGURE l the target electrode utilized in the image reproducing tube 22 which is shown in FIGURES 2A and 2B will be considered.

The target electrode as shown in FIGURES 2A and 2B consists of a foundation plate 50 having strip-like color light producing elements R, B, and G positioned thereon. As taught by Leverenz in United States Patent No. 2,310,863 when the light producing phosphor elements which make up the different groups are to emit blue, green and red light, respectively, the materials of which the elements are composed may comprise: silver activatedv zinc sulfide and zirconium silicate for the blue elements B, alphawillemite activated with manganese or zinc cadmium sulfide activated with silver for the green elements G, chromium-activated aluminum berylliiate or zinc cadmium sulfide activated by silver for the red elements R.

Every Ifourth element position in the pattern of the image screen is opaque and unoccupied by light producing material in the plane of the light producing elements R,`B, and G. Positioned upon the light producing elementsy R, B, and G is. an electron-transparent light-refleeting layer 52 which may be composed of aluminum. A series of ultra violet light emitting phosphor coating elementsl 54 are then positioned in registry with one side of the strip-like area which is unoccupied by light producing material. The ultra violet light emitting elements may be composed of calcium magnesium silicate, .zincY oxide or other fast phosphor materials.

In regard to the operation of the system shown in FIGURE 1 it is desired to control the gate circuits 12, 14, 16 and 18 by the application of gating signals in such av manner that the electron beam in the image reproducing tube 22 is sequentially modulated with the following different signals: a red signal, a blue signal, a green signal and -a substantially unvarying signal. The intervals during which the electron beam is modulated with these different signals must coincide with the intervals` during which the electron beam impinges upon the diiferent strip-like color light producing elements on the image screen within the reproducing tube 22. During the time when the electron beam impinges upon the signal generating elements, or in this case the ultra violet light emitting elements of thetarget electrode which in this form of the invention are utilized as the signal generating elements, ultra violet light will be emitted. The ultra violet light control signals are sensed through the light filter 37 by the photoelectric cell 36 positioned in a window of the image reproducing tube 22. The control signals sensed by the photoelectric cell 36 will be filtered by the band pass filter 38 and then applied to the variable phase shift circuits 24, 26, 28 and 30, wherein there are formed four gating signals each of which is shifted `substantially 90 from the other. The 90 phase shifted gating signals when applied to the gate circuits 12, 14, 16 and 18wwi1l therefore sequentially allow the passage of the substantially unvarying signal through the gate circuit 18, the green signal through the gate circuit 12, the blue signal through the gate circuit 14 and the red signal through the gate circuit 16, to the cathode 21 of the image reproducing tube 22. As these signals are sequentially applied to the cathode 21, the electron beam in the tube 22 will be intensity modulated according to the intensity of the gated signals. The low pass controlsignalpassing through the low pass lter 3 8 is utilized to sensitively control the amount of phase shift elected by the variable phase shift circuits 24, 26, 28 and 30. The low pass control signal is separated in the low pass filter 34 and amplified in the D.C. amplifier 32 and results in a phase shift control signal. The phase shift control signal is utilized as a correction signal to vary the degree of phase shift effected by the variable phase shifter circuits 2,4, 26, 28 and 30, and thereby effectively assures correct beam modulation with respect to the electron beam position.

The manner in which the phase shift control signal is utilized will be explained with reference to FIGURES 3A, 3B land 3C. There is shown in FIGURES 3A, 3B and 3C an enlarged portionof the ultra violet light emitting element 54 and the adjacent opaque area 55. Areas 60, 62, 66, 68, 74 and 76 represent various areas on which an electron beam within the image reproducing tube may impinge upon the target electrode. Though an electron beam of a square cross section is shown, such is the case only for purposes of illustration, and it may be seen, that more irregular electron beams will give satisfactory performance.

Consider iirst- FIGURE 3A and assume that the electron beam has been receiving a substantially unvarying potential for atime since it was in a position as to impinge on the dashed line enclosed area 60 where it carne initially in contact with the ultra violet light emitting element 54. Assume further that the electron beam became turned off, so to speak, i.e., dropped to a low intensity level upon reaching a position as shown by a solid line enclosed area 62. There is shown a curve 64 which. indicates the control signal generated when the electron beam is turned on at a position shown by area 6,0 and turnedoff at a. position shown by area 62. The curve 6,4v will be seen to be representative of a control signal of continually increasing magnitude as the electron beam. is moved on to the element 54 causing a greater number of the electrons within the electron beam to impinge upon the ultra violet light emitting phosphor element 54.

Referring now to FIGURE 3B there is shown a control signal which would be generated if the electron beam were keyed on to a substantially unvarying intensity when inV position as shown by dashed line enclosed. area 66, and werekeyed. oif when in a position substantially as shownby solid line enclosed* area 68. It may be seen that the control signal as shown in curve 70 will be generated having increased direct current component over theL control signal shownv by the curve 64. In the case as shown in FIGURE 3B it will be seen that the electron beam has been keyed on at a time later than t-he case shown in FIGURE 3A-or phase time delayed.

Referring now to FIGURE 3C there is'shown a control signal incurve 72 which is representative of the signal which wouldbe generated if the electron beam were keyed onat the position asshown by the dashed line enclosed area 74 and keyed off at the position shown by the solid line enclosed area v76. In considering the curves 64, 70, and 72, it will be seen that as the gating or keying signal is varied inphase with respect to the scanning of the signal generating elements the generated signal will vary both in'magnitude and peak intensity.

A consideration of the FIGURES 3A, 3B, and 3C indicatesthat the frequency ofthe control signal and the amplitude ofthe control signal will be indicative, of the position of the electron beam. The bandpass control signalthus becomes a signalwhich in frequency isindicative of the number ofsignal generating elements scanned by the electron beam during a particular period. The bandpass control signalvmay, thus be utilized to generate the gating signals for switching the Kapplication of the different color signals andthe unvarying voltage to the cathode 20 of image reproducing vtube- 2.2.1 A'l similar Switching. mengementis. .shQwnand-- descnibedgin United S States Patent No. 2,545,325, issued to P. K. weimer, March 13, 1951.

The amplitude and the direct current component .of the control signals shown in curves 64, 70 and 72 may be seen to vary as the interval during which the electron beam is keyed to a substantially unvarying voltage in relation to the deflected position of the electron beam on the target electrode. If the keying is properly timed with respect to the scanning of the signal generating element 54, the control signal will be of an amplitude as shown in curve 64. If the keying to substantially unvarying Voltage is delayed with respect to the signal generating element 54, as shown by FIGURE 3B, the control signal will be of increased amplitude and have a greater direct current leomponent las shown in curve 70, than it had in curve 54. If the keying of fthe electron beam intensity to a substantially unvarying value is premature with respect to the signal generating element `54, as shown in FIGURE 3C, then a control signal of lesser amplitude and having a smaller `direct current component will be generated as shown by curve 72. It may therefore be seen that the low pass control signal which varies as the direct current component of lche control signal is a sensitive indication of the timing relationship of the electron beam intensity modulation with respect to the position of the electron beam. The low pass control signal may therefore be utilized las a phase shift control signal to vary the degree of phase shift effected by the variable phase Shifters 24, 26, 28 and 30. The control signal amplitude or condition which exists as shown in FIG- URE 3A may be set as an equilibrium condition, and if the control signal generated increases in magnitude 'and direct current component the phase of the gating signals will require to be phase advanced, whereas if the control signal generated decreases in magnitude and direct current component, it will be indicated that the phase of the gating signals should be phase delayed.

Referring now to FIGURE 4 there is shown another form of the invention illustrated by a system having an image reproducing tube 22 with a target electrode substantially as shown in FIGURES 2A and 2B. Components of the systems shown in FIGURE 4 which are similar to components in FIGURE l are similarly numbered.

The television receiver is utilized to generate a green signal, a blue signal, and a red signal. The various color component signals are applied sequentially along with `a substantially unvarying signal to the cathode 21 of the image reproducing tube 22 to sequentially modulate the electron beam as described with reference to FIGURE l. The gate circuits 12, 14, 16 and 18 are controlled by phase Shifters 82, 84, 86 and 88 which are not variable. 'Il-he phase Shifters 82, 84, 86 and 88 act upon signals received from -an oscillator 90 to produce diierent gating signals each being substantially 90 displaced from the other to be utilized to control the gate circuits 12, 14, 16 and 18. The control signal sensed as previously described by the photoelectric device =36 through the lter 37 is passed through the low pass ampliiier 34 and thence applied to auxiliary `deflection plates 92 positionedl within the image reproducing tube 22.

In the system as shown in FIGURE 4 the variation to correct for deviation in the timing between the intervals during which the electron beam is intensity modulated With the different component color signals, and the i11- tervals during which the electron beam i-mpinges upon the diiferent light producing strip-like elements of the image screen is made by Varying the time of occurrence of the impinging intervals by utilizing the auxiliary deecting plates 92 to alter the beam position. That is t0 say, 'if the electron beam is being modulated by, for example, a green signal but is still impinging upon `a blue color producing element, the auxiliary deflecting means 92 will tend to deflect the electron beam as it scans further to cause'the period during which the beam is intensity modulated with a green component signal to coinbetween the interval of modulation, and the interval ofV f 6 cide with the period during which the electron beam impinges upon the ygree light producing element.

It may therefore be seen by comparing FIGURES 1 and 4 that in diierent forms of the invention a correction signal may be formed to vary the position of the electron beam of the intensity modulation intervals of the electron beam, to maintain the correct relationship beam impingement.

FIGURE 5 shows a form of a variable phase shifter which may be used as the variable phase shifter circuits 24, 26, 28 and 30 of VFIGURE 1. Terminal 100 is provided for receiving a direct current voltage which varies as the amount of phase shift desired. 'I'he direct currenty voltage applied vat terminal 100 will pass through inductive elements 102 and 104. The inductive elements 102 and 104 are inductively coupled to inductance elements 106 and 108. The inductance elements 106 and 108 form part of a delay line 110 which also includes capacitors 112, 114 and 116. An alternating current signal applied at terminal 118 will be phase delayed by a prei determined amount on passing through the phase delay line 110. The application of a direct current voltage to terminal will vary the inductance reactance of the induotance elements 106 and 108 and will therefore vary the degree of phase shift affected by the delay line 110. It may therefore be seen that if the low pass control signal is applied to the terminal 100, and a bandpass control signal is applied to the alternating current terminal 118, the low pass control signal will vary the phase delay aifected in the bandpass signal by the delay line according to the amplitude of the low pass control signal.

FIGURE 6 shows a form of a gating circuit which may be used as the gating circuits 12, 14, 16 and 18. A gating signal is applied to the terminal 122. The signal to be gated is applied at the terminal 124. Both terminals 122 and 124 are connected to current control grids of an electron discharge device 126. The current through the electron discharge device 126 will therefore be controlled by the potential applied at the terminal 122 and 124. The electron discharge device 126 is so biased that until the gating signal applied at terminal 122 reaches a predetermined amplitude, no signal will pass through the electnon discharge device 126 and no alternating signal will appear at the output terminal 128. Upon the occurrence of a gating signal above a predetermined magnitude the electron discharge device 126 Will become conducting, however, the current through the device will be modulated in accordance with the signal applied at the terminal 124. In this manner a gated color signal may be caused to periodically appear at the output terminal 128 upon the occurrence of a gating signal applied at the terminal 122 of a particular amplitude.

In the event that the direct current signal from the peak detector 40 of FIGURE l decreases in amplitude the decrease will be sensed by the connection from the peak detector 40, and cause the photocell 36 to receive a voltage of increased magnitude thereby regulating the amplitude of the control signal to compensate for power fluctuations.

FIGURE 7 shows a form of photocell voltage control circuit 44 which may be used in the system of FIGURES l and 4. Terminal 130 is adapted to be connected to a source of negative potential. The negative potential is coupled through cathodes in electron discharge devices 134 and 138. The electron discharge device 134 has a control grid connected through a battery 136 to a plate of the elect-ron discharge device 138. The electron discharge device 138 acts as a direct current amplifier and thereby applies a potential to the control grid of the electron discharge device 134. As the cathode potential at the electron discharge devices 134 and 138 varies, the output voltage appearing at terminal 140 will also vary because Ythe potential is dependent upon the voltage applied to the control grid of the tube 138. It may there,

fore ,be seen that the output potential appearing at terminal 140 will vary vas the input signal applied at the electron discharge device 138 through input terminal 142 and the signal from the .peak detector 40 of FIGURE 1 may be applied at the input terminal 142 to vary the phototube voltage control circuit, and thereby Vary the voltage supplied at the photoelectric cell 36.

lIn still another form of this invention a well regulated Voltage supply may be applied directly to thephotocell 36 .without employing the photocell voltage control circuit including the photocell voltage control circuit 44, the D.C. amplifier 42, and the peak detector 40.

It may therefore be seen that the invention provides an improved system for reproducing color images, utilizing asingle electron beam with apparatus to maintain the registry of the electron beam correct with respect to the image reproducing screen.

What is claimed is:

l. An electron beam control system comprising a target electrode having a plurality of light producing elements and a plurality of signal generating elements, said light producing elements being responsive to emit light energy when excited by electron beam energy, said signal generating elements being responsive to generate a control signal including low frequency components when excited by electron beamrenergy, means for forming an electron scanning beam for exciting said elements, controlled modulating means for intensity modulating said electron beam with different values during different time intervals of modulation including a reference value at times when said beam impinges upon said signal generating elements, each lof said time intervals of modulation substantially coinciding with a particular impinging time interval during which said electron beam excites certain of said elements, frequency discriminatory sensing means for sensing the amplitude of the low frequency components of said control signal, varying means connected to receive said control signal, said varying means for varying said time interval of modulation with respect to said particular impinging interval in accordance with the amplitude of said control signal.

2. A device according to claim l wherein said varying means comprises dellecting means for deilecting said electron beam commensurate with said control signal to thereby vary the time of occurrence of said impinging interval.

3. A device according to claim l wherein said varying means comprises switching means connected to said modulating means, said switching means being such as to vary the time of occurrence of said interval of modulation commensurate with said control signal.

4. A color television image reproducing system comprising in combination a target electrode having a plurality of light producing elements. and a plurality of signal generating elements, said light producing elements being responsive to emit light energy when excited by electron beam energy, said signal generating elements being responsive to generate a control signal when excited by electron beam energy, means for forming an electron scanning beam for exciting said elements, gating means adapted to be connected to sources of a plurality of different signals including a source of unvarying signal, beam intensity control means connected ,to said gating means, said gating means being operative to modulate said beam with said unvarying signal at times related to the impingement of said beam upon said signal generating elements, sensing means for sensing said control signal ygenerated by said signal generating elements, variable phase shift means connected to said sensing means for generating a phase shifted gating signal for each of said different signals, means for applying said gating signals to said gating means such as to control the application of said different signals to said beam intensity control means for modulating said electron beam sequentially with said different signals, means for isolating the low frequency components of said control signal to form a phase control signal, and means for applying said phase control signal to said variable phaseshift means for varying the phase shift effected by said variable phase shift means as a function of the amplitudeA of said low frequency components. Y

5. A color television image reproducing system comprising in combination a target electrode having a plurality of light producing strip-like elements., and a plurality of signal generating strip-like elements, saidlight producing strip-like elements being responsive to emit light energy when excited by electron beam energy, said signal generating strip-like elements being responsive to generate a control signal when excited by electron beam energy, means for forming an electron scanning beam for exciting said strip-like elements, gating means adapted to be connected to sources of plurality of different signals including an unvarying reference signal, beam intensity control means connected to said gating means, sensing means for sensing said control signal generated by said signal generating strip-like elements, variable phase shift means connected to said sensing means for generating a phase shifted -gating signal for `each of said different signals, means for applying said gating signals to said gating means such as to control the application of said different signals to said beam intensity control means for modulating said electron beam sequentially with said different signals and with said reference signal when said beam impinges upon a signal generating element, means for isolating certain frequency components of said control signal to form a phase control signal indicative of the amplitude of said certain frequency components, means for applying said phase control signal to said variable phase shift means for varyu'ng the phase shift effected by said variable phase shift means as a function of the amplitude of said certain frequency components, and means for receiving certain frequency components of said control signal for controlling variations in said sensing means. y

6. A color television image vreproducing system comprising in combination a target electrode having a plurality of light producing elements and a plurality of signal generating elements, said light producing elements being responsive to emit light energy when excited by electron beam energy, said signal generating elements being responsive to generate a control signal including low frequency components when excited by electron beam energy, means for forming an electron scanning beam, electron beam dellection means for deflecting said electron scanning beam in a scanning pattern to excite said elements, gating means adapted to beconnected to a plurality of sources of different signals including an unvarying reference signal, beam intensity control means connected to said gating means, sensing means for sensing said control signal generated by said signal generating elements, phase shift means connected to said sensing means for generating from said control signal, a phase shifted gating signal for each of said different signals, means for applying said phase shifted gating signals to said gating means such as to control the application of said different signals to said beam intensity control means for modulating said electron beam sequentially with said different signals and with said reference signal when said beam impinges upon a signal generating element, means for isolating said low frequency `components of said control signal to form a deflection correction signal, auxiliary deilecting means for imparting additional deflection to said electron beam, and means for applying said deflection correction signal to said auxiliary deflection means to control deflection of said beam as a function of the amplitude of said low frequency components of said control signal.

7. A color television image reproducing system comprising in combination a target electrode having aplurality'of light` producing strip-like elements and a plurality of signal ygenerating strip-like elements, said light aesasa elements being responsive to emit light energylI when excited by electron beam energy, said signal generating strip-like elements being responsive to generate a control signal including low frequency components when excitedV by electron beam energy, means for forming an electron' scanning beam, electron beam deflection means for'ldeiiecting said electron scanning beam in a scanning pattern to excite said elements, gating means adapted to be connected to a plurality of sources of diiferent signals, b'eam intensity control means connected to said `gating means, sensing means for sensing said control signal generatedby said signal generating strip-like elements, phase shift means connected to said sensing means for generating from said control signal a phase shifted keying signal for each of said different signals, means for applying said gating signals to said gating means such as to control the application of said ldierent signals to said beam intensity control means for modulating said electron beam vsequentially with said different signals and with an unvarying Areference signal at times related to the times of beam impingement upon said signal generating elements, means' for isolating saidlow frequency components of said control signal'to'form a deilection correction signal, auxiliary deecting means 4for imparting additional deflection to said electron beam, means for applying said deflection correctionsignal totsaid auxiliary deilection means, and means 'adapted to receiye saidlow frequency components forfcontrolling the voltagesupplied to said sensing means.

"8. Iny a color television system embodying a color kinescope having a target formed of groups of strip-like elements, each. .group of strip-like elements for producing light ivithinaparticular range of Wave lengths whenl excited byelectron beam energy, at least oneof said groups ofl'strip-like elements' forV producing a control signal including low frequency components, means for generating an j electronubeam ,for exciting said Vstrip-like elements, beam modulating means for modulating said electron beam alternately with different signals and for modulating said beam to a reference value at times related to its impingement upon said control signal producing elements, means for controlling said beam modulation means, means for sensing said control signal, means for selecting said low frequency components of said control signal to form a correction signal which varies as a function of the amplitude of said low frequency components, means for coupling said correction signal to said means for controlling said beam modulation means such as to cause said electron beam to be modulated with a signal representative of light within a particular range of wave lengths at a predetermined time.

9. A color television system embodying a color kinescope having a screen formed of groups of strip-like elements, each group of strip-like elements for producing light within a particular range of wave lengths when excited by electron beam energy, at least one group of strip-like elements for producing a control signal including low frequency components when excited by an electron beam, means for generating an electron beam for exciting said strip-like elements, beam modulating means for modulating said electron bearn alternately with diierent signals and for modulating said beam to a reference value at times related to its impingement upon said control signal producing elements, means for sensing said control signal, feedback means for maintaining the sensitivity of said sensing means substantially constant, means for selecting said low frequency components of said control signal to form a correction signal, auxiliary beam deflection means, means for coupling said correction signals to said auxiliary beam dellection means for controlling said beam deflection such that to cause said electron beam to be modulated with a signal representative of light within a particular range of wave lengths at a predetermined time.

l0. A color television image reproducing system coml prising in combination a target electrode having a plurality of light producing elements, and a plurality of sigl of gating circuits, each of said gating circuits being connal generating elements,

being responsive to generate a control signal including beam energy, means for forming an electron scanning beam, means for deilecting said electron scanning beam in such a manner as to excite said elements, Aa plurality nected to a source of a dilerent signal, beam intensity control means connected to said gating circuits, sensing means for sensing said Vcontrol signal generated by said signal generating elements, feedback means for maintaining the sensitivity of said sensing means substantially con-" stant, variable phase shift means connected to said sensing means for generating a phase shifted gating signal for each of said different signals, means for applying each of said gating signals to one of said gating circuits such as to control the application of said different signals to said beam intensity control means for modulating said'electron beam sequentially With said different signals and for modulating said beam to a reference value at times related to its impingement upon said control signal producing elements, means for isolating said low frequency components of said control signal to form a phase control signal, and means for applying said phase control signal to said variable phase shift means for varying the phase shift effected by said variable phase shift means.

beam energy, means for forming an elect-ron scanning beam, electron beam deilection means for deflecting said electron scanning beam in a scanning pattern to excite said elements, a plurality of gating circuits, means for connecting each of said gating circuits to a source of a diierent signal, beam intensity control means connected to each of said `gating circuits, sensing means for sensing said control signal generated by said signal generating elements, feedback means for maintaining the sensitivity of said sensing means substantially constant, phase shift means connected to said sensing means for generating from said control signal a phase shifted gating signal for each of said different signals, means for applying said phase shifted gating signals to said gating means such as to control the application of said different signals to said beam intensity control means for modulating said electron beam sequentially with said different signals and for modulating said beam to a reference value at times related to its impingement upon said control signal producing elements, means for isolating said low frequency components of. said control signal to form a deection correction signal, auxiliary deflecting means for imparting additional deflection to said electron beam, and means for applying said deflection correction signal to said auxiliary deflection means.

l2. A color television image reproducing system comprising in combination a target electrode having a multiplicity of groups of light emissive elements, said light emissive elements each being constituted essentially of a phosphor material capable of emitting light of a color individual to that element, said light emissive elements being so positioned as to leave certain areas on said target electrode void of phosphor material, a plurality of discrete phosphor coatings disposed on said target electrode within said certain areas, said discrete phosphor coatings being responsive to generate a control signal including low frequency components when excited by electron beam er1- ergy, means for forming an electron scanning beam, means for deflecting said electron scanning beam in such a manner as to excite said elements, a plurality of gating cirsaid light producing` elements being responsive to emit light energy when excited by' electron beam energy, said signal generating elementscuits, each of said gating circuits being connected, toa

source o fga different signal, beamintensity control means conneted'to said` gating circuits, sensing means for sensing ,saidY control 4signal generated by said discrete phosphor4 coatings, feedbackv means for maintaining the sensitivity ofsaid sensing means substantially constant, variable phase shift means connected to said sensing means for generating a phaseshifted gating signal for each of said different signals, meansfor applying each of said gating signals to one of said gating circuits such as to control the application of said different signals `to said beam intensity control means for modulating said electron beam sequentially with said different signalsand for modulating said beam to avreference value at times related to its impingement upon said control `signal producing elements, means for isolating said low frequency components ofsaid con-trol signal to form a phase control signal whose amplitude varies as a function of the amplitude of said low frequency components, and means for applying said phase control signal to said variable phase shift means for varying the phase shift eifected by saidvariable phase shift means.

13. A color television image reproducing system comprising in combination a target electrode having a plurality of light-producing strip-like elements, and a plurality of signal-generating strip-like elements, said lightproducing strip-like elements being responsive to emit light energy when excited by electron beam energy, said signal generating strip-like elements being responsive to generate a control signal including high and low frequency components when excited by electron beam energy, means for forming lan electron scanning beam for` exciting said strip-like elements, gating means adapted to be connected to` a plurality of sources of diicrent signalsincluding an unvarying reference signal, beam intensity control means connected to' said gating means, sensing means for sensing said control. signal generated by, saidV signal generating` strip-like elements, variable phase, shift means connectedj to said sensingmeans for generating fromfthe-.high,fre-l quency component of' said control signal a phaseA shifted` keyingsignalfor eachof said different signals, means for,l

applying said, gating signals to said gating means suchV as,

tocontrol theV application of said different signals to said.

beam intensity control means for modulating said electron beam sequentially with said different signals and with saidl unvarying reference signal at the `times of beamimpingef ment upon said signal generating elements, means .connected to said sensing means for generating a phase control signal from the low frequency component of said control signal, means for applying said phase control signal to said variable phase shift means for varying the phase shift effected by said variable phase shift means as a function ofthe amplitude of lthe high frequency component of said ycontrol signal, and feedback means connected to said sensing means and responsive to the low frequency component of ysaid control signal for controlling variations in said sensing means.

ReferencesCited in the le of this patent.v

UNITED STATES PATENTS 2,633,547 Law Mar. 31,1953 2,635,141 Bedford Apr. 14, 1953 2,648,722 Bradley Aug. 1l, 1953 2,664,520 Wiens Dec. 29, 1953 2,689,269 Bradley Sept.,14, 1954 2,706,216 Lesti Apr. 12, 1955v 2,752,418 Clapp June 26, 1956 2,771,503 Schwartz NOV. 20, 1956 2,837,687 Thompson et al June 3, 1958 FOREIGN PATENTS 616,012 Great BritainV Jan. 14, 1949-

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