US3431456A - Three beam color television deflection system - Google Patents

Description

March 4, 1969 A. LIEBSCHER 3,431,456

THREE BEAM COLOR TELEVISION DEFLECTION SYSTEM Filed Aug. 3, 1966 CONTROL C/RCU/T AMP. /7

SAM T0077! GEN 3 R0 HARM C. GEN.

MATRIX &

DEA/00 lNVE/VTOR ARTHUR L/EBSCHER ATTORNEY 3,431,456 THREE BEAM COLOR TELEVISION DEFLECT ION SYSTEM Arthur Liebscher, 252 Wyncote Road, Jenirintown, Pa. 19046 Filed Aug. 3, 1966, Ser. No. 569,957 US. Cl. 315--13 Int. Cl. H01j 29/ 50, 29/70 10 Claims ABSTRACT OF THE DISCLOSURE This invention relates to a television picture tube, and more particularly to a tube having a single-cathode electron gun which provides a triple beam, simultaneous color-element display.

In the past, the basic designs of color television picture tubes have been associated with either simultaneous or sequential color-element display. Both types of color picture tubes are compatible with the standard color-video signal specifications which have been adopted by the Federal Communications Commission.

'In color television picture tubes designed for simultaneous color-element display, it is typical to employ a plurality of electron guns, for example three. These electron guns are arranged so as to focus the individual electron beams produced thereby upon a respective color-reproductivephosphor deposit which is distributed throughout the screen area. Thus, each electron gun may be considered to be operative to provide a specific color-signal selecting electron beam. In the simultaneous display apparatus, the amount of each color reproduced at the color reproductive phopshor deposits is controlled by a proportionate color-signal control circuitry. Properly proportioned intensities of the three basic colors (blue, green and red) blend to produce an optical impression of white light. That is, white light is produced by the properly proportioned intensities of the three basic colors and upon simultaneous illumination of the three color-reproductivephosphor elements by the electron beams. Such simultaneous illumination is obtained by the precision alignment of the three electron beams produced by the respective guns. The focusing arrangement for this type of tube includes a plurality of grids and the like associated with each electron gun. In addition, the focusing arrangement is so designed to control the electron beams produced by the guns such that the respective beams penetrate a perforated mask adjacent the phosphor deposits on the screen area. This focusing control assures that the proper phosphor deposit in a triangularly arranged tricolor phosphor dot array is activated. That is, the proper electron beam impinges on the phosphor deposits at the proper angle to generate a response by the specific phosphor dot. It is inherently obvious that in this type of apparatus the alignment of the device is critical. Furthermore, this critical alignment is subject to the position of the picture tube with respect to the magnetic field of the earth. Therefore,

States Patent 'ice this type of tube is diflicult to maintain and readily causes problems for the user.

In the sequential type of tube there is typically employed a single gun electron beam source. Again, each tube includes a screen area which incorporates color-reproductive phosphors thereon. In the sequential type of tube, the screen may typically include a ruled-grid type of area having a repetitiously arranged tricolor-element sequence. -In this apparatus, the electron beam is focused by a focusing arrangement which will vary the intensity and position of the electron beam. This variation of the electron beam produces the color reproduction by the selected phosphors. By proportionate variations of the beam intensity as a three-bar color element is scanned, an optical impression of white light is achieved. However, because of the division of a tricolor sequence to approximately one-third exposure time for each of the colors, the total light output is generally considered to be less than that of the previously described simultaneous exposure. On the other hand, the sequential tube has the advantage of eliminating a shadow mask requirement as Well as being relatively unaffected by the earths magnetic field effect whereby maintenance of alignment is simplified.

Thus it is seen that the single gun sequential type color picture tube is more readily adaptable to mass production whereby lower costs are achieved than are possible in the three gun simultaneous type. This reduction in cost for a sequential type tube having a single gun is available even though some color-registry device may be necessary in conjunction with the sequential tube and the related circuitry.

This invention is designed to incorporate the advantageous features of both the simultaneous and sequential type picture tubes in order to permit the production of a color television picture tube which is relatively inexpensive. In this invention, a color television picture tube is designed wherein a single electron gun which generates a plurality of electron beams, for example three, is utilized. The focusing means associated therewith include proper deflection means for advancing all three electron beams simultaneously and instantaneously from one group of tricolor elements to the next whereupon the three beams dwell momentarily and simultaneously to produce another element of color video.

Thus an object of this invention is to provide a color television picture tube which is capable of simultaneous energization of a plurality of color reproductive phosphors while using only a single electron gun.

Another object of this invention is to provide a color television picture tube, as noted above, which is relatively inexpensive to produce.

These and other objects and advantages of this invention will become more readily apparent when the following description thereof is read in conjunction with the attached drawing which is a schematic diagram of the invention in an exploded view.

Referring now to the drawing, there is shown, schematically, a preferred form of the invention. In this embodiment, there is provided the usual evacuated envelope 20, fabricated of glass or other suitable material. This envelope embodies the typical flaring frusto-conical or pyramidal shape with a viewing area at one end and a narrow neck at the other end. Within the envelope there is contained a filament or heater element 1 which is contained within a thermo-emissive cathode housing 2.

The heater and cathode housing element are any typi cal heater and cathode elements which serve as the emission source for a video modulated flow of electrons. The video modulated flow of electrons or electron beams, is gated by grids 3, 4, 5. Each of the grids is connected to modulating network 12 via a conductor 12A. The grids 3, 4 and 5, in conjunction with the modulating signal supplied thereto, control the flow and form of red, green and blue designated electron beams respectively. That is, the electron beams provided by the emission source are individually controlled in accordance with the signals supplied to the respective grids.

The electron beams are substantially focused by the grids 3, 4 and 5 to pass through apertures in the mask 19. The mask 19 and apertures operate to define the diameters of the beams. The respective beams are then accelerated through the anode 6 which may be in the form of a cylindrical sleeve or the like. Anode 6 provides a preliminary acceleration to the streams of electrons. After the beams have been accelerated by the anode 6, they are focused by means of the permanent magnet 7 to provide well defined spots at the screen, which are images of the apertures in mask 19. The sweep step deflection plates 8 are connected to the 10.7 megacycle per second saw-tooth generator 16 whereby horizontal control is effected in the form of proper sweep step deflection. After passing through the deflection plates 8, the electron beams pass through coil or yoke 9. Yoke 9 is the raster control coil for the electron beams providing both vertical and horizontal deflection. Finally, after the beams pass through coil 9, further anode 10 is provided to produce further acceleration of the electron beam. The beams ultimately impinge upon the color reproducible phosphors at the screen 11. Suitable potentials for the various electrodes of the tube are provided by the source and related control circuitry 21.

The phosphors on the screen are arranged in vertical strips or stripes 11 in the conventional sequence of red, green and blue, with like color responsive groups repeated across the entire screen area. Non-luminous, conductive stripes or strips 11A are interspersed across the screen area intermediate the phosphor stripes. The conductive stripes are utilized to obtain feedback pulses from the electron beam transition thereacross. These non-luminous stripes can also be used to discharge the beam spot area which exceeds the phosphor line width and thereby reduce color fringing.

The non-luminous conductive strips 11A are connected to the phase detecting network 18. Also connected as an input to the phase detector network 18 is the output of the third-harmonic sync. generator which is connected to the output of the 3.58 megacycle per second oscillator 14. The phase detection network at the output thereof is connected to an input of the AGC sync. amplifier 17 which, together with the third-harmonic generator 15 supplies input signals to the 10.7 mc./s. saw-tooth generator 16. As noted above, the saw-tooth generator 16 is connected to the deflection plates 8, so as to provide an inverted saw-tooth action on the beams giving resultant voltage increments to produce step and dwell advancement upon horizontal line scan.

The 3.58 megacycle per second oscillator is also connected as an input to phase detector 13. The output of the phase detector 13 is connected to the matrix and demodulating network 12. The demodulating circuitry is connected, via conductors 12A, to the respective grids 3, 4 and 5 to control the operation thereof.

Referring again to the figure it is obvious that the heater 1 provides the thermal control whereby emission source 2 produces the triple beam or three separate electron beams. These beams, which are labeled R, G, B, are then controlled by grids 3, 4 and 5 in accordance with the signal which is applied thereto by the matrix and demodulating network 12. The matrix and demodulating network 12 is controlled by the signals supplied thereto via phase detecting network 13. Phase detecting network 13 receives signals from the 3.58 megacycle per second color sub-carrier oscillator circuit 14 which may be crystal controlled. Signals are applied to phase detector 13 and the oscillator circuit 14, respectively, by input lines which are connected to a receiver (not shown). The

4 1 receiver may be any typical television receiving network including any necessary antenna or the like.

In accordance with the signal supplied by the receiver, the grids 3, 4 and 5 operate on the respective electron beams R, G, and B whereby these electron beams are controlled. The beams pass through mask 19 to produce a beam of desired diameter and are accelerated by the anode sleeve 6. The electron beams are further focused by permanent magnet 7. Coil 9 and the associated circuitry 21 may be any conventional deflection system for controlling and positioning the electron beams.

Deflection plates 8 simultaneously control the horizon tal deflection of the electron beams. That is, the inverse saw-tooth deflection signal supplied to plate 8 is supplied by 10.7 megacycle saw-tooth generator 16 thereby causing the electron beams to be deflected horizontally. The 10.7 megacycle saw-tooth signal is supplied by any typical 3.58 megacycle oscillator via a known type of thirdharmonic amplifier 15. The third-harmonic amplifier is effective to lock the saw-tooth wave to the oscillator in order to assure and promote stability of the network. Coil .9 provides the raster deflection of the electron beam in order to provide the proper pattern at the target area 11.

The electron beams which have been focused and accelerated by the remainder of the circuitry impinge upon the phosphors in the target area. For example, the red, green and blue electron beams impinge selectively upon the red, green and blue phosphor strips. Thus, as the color control signals are supplied by saw-tooth generator 16 in accordance with the color-sub-carrier signal supplied by oscillator 14, the electron beams are switched or stepped along the horizontal scanning line in time with the color phasing. This color phasing can be controlled and registered by means of having feedback signals produced by the screen, for example along the strips 11A, as the electron beams sweep thereacross. The feedback signals are applied along line 22, for example, to the phase detecting network 18. This network, in addition, receives the signal from the third-harmonic sync. generator 15 and compares the feedback signals thereto. Thus, the feedback signals are, in essence, phase compared with the signal produced by the crystal oscillator and applied to the saw-tooth wave form generator via the AGC sync. amplifier 17. Thus, the amplifier 17 operates to adjust the frequency of the saw-tooth signal and thereby control the length of the dwell time of the beam-step deflection.

It is apparent that there is produced herewith an improved color television tube having advantageous properties. In this description, a preferred embodiment is described. This embodiment is not meant to be limitative of the invention inasmuch as alternate principles may be included. For example, a filter screen ruled with color lines and interspersed with a heat producing line for infrared detection will enable the forgoing advantages of color reproduction and self-contained phase lock-in when a white phosphor screen is used as illumination with the triple beam deflection as heretofore described. In this alternative embodiment, white dots represented at the screen are post-illumination colored by the filter to produce a color picture. That is, control impulses may be generated by a photocell detection of filtered colored lights which are operative to produce the image at the target area.

In another alternative embodiment, colored luminous strips on a panel or wall may be made responsive to projected beams of white light from a fluorescent tube and lens system. The color may be synchronized by means of photoelectric pickups of infrared responsive stripes. These embodiments are not shown inasmuch as the techniques are known in the art and the basic principles and advantages of this invention are shown and described with respect to the single figure.

As noted above, the showing and description are not meant to be limitative to the invention, but rather the inventive concepts are more generically defined in the appended claims.

tube comprising means for simultaneous generating a plurality of separate electron beams,

raster deflecting means providing a signal for simultaneously deflecting each of said beams, and

additional deflecting means actuated by a saw tooth signal inverse to the raster signal of higher frequency than the frequency of said raster signal,

said deflecting means providing a resultant simultaneous stair case deflection of said plurality of beams for simultaneously advancing said beams in timed relation along and confined to the axis of deflection, and

chromatic responsive means to which said beams are directed.

2. The combination as defined in claim 1 in which input signal means is provided in phase controlling relation to said additional deflecting means.

3. The combination as defined in claim 1 in which input signal means is provided in synchronized controlling relation to said additional deflection means.

4. The combination as defined in claim 1 in which said tube has a face with a portion of said responsive means thereon, and

the remainder of said responsive means including synchronizing and color receptive areas, is exteriorly disposed with respect to said tube and in spaced relation to said face.

5. The combination as defined in claim 1 in which said chromatic responsive means comprises a plurality of color receptive areas to be energized by said electron beams.

6. The combination as defined in claim 5 in which said color areas are disposed on a face of said tube.

7. The combination as defined in claim 5 in which indexing members are provided associated with said areas, and

feed back means is provided between said indexing member and one of said deflecting means.

8. The combination as defined in claim 7, in which said areas comprise oriented phosphor strips and have conductive elements associated therewith connected to said feedback means.

9. The combination as defined in claim 8 in which said areas and said conductive elements are disposed on a face of said tube.

10. A color television tube comprising a single cathode which is capable of simultaneously generating three separate electron beams,

raster deflecting means providing a signal for simultaneously deflecting each of said beams,

additional deflecting means actuated by a saw tooth signal inverse to the raster signal of higher frequency than the frequency of the raster signal,

said deflecting means providing a resultant simultaneous staircase deflection of said plurality of beams for simultaneously advancing said beams in timed relation along and confined to the axis of deflection,

said tube having a face with a plurality of phosphor areas thereon to be energized by said electron beams and non-luminous conductive elements disposed between said phosphor areas to produce signals when traversed by said electron beams and as advanced by said deflecting means, and

feedback means connected between said non-luminous conductive elements and said additional deflecting means providing phase control for said deflecting means and regulating step-frequency and dwell time of said electron beams simultaneously.

4 RODNEY D. BENNETT, JR., Primary Examiner.

M. F. HUBLER, Assistant Examiner.

US. Cl. X.R.

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