US2749474A - Regulated high voltage supplies - Google Patents

Description

June 5, 1956 J. o. PREISIG 2,

REGULATED HIGH VOLTAGE SUPPLIES Filed June 29, 1954 2 Sheets-Sheet l 11 F1 YiiC/t z :04 55 F2 yew/z z PULSE $0036! I N V EN TOR. JOSE H a P/FE/S/' J. o. PRElSlG REGULATED HIGH VOLTAGE SUPPLIES June 5, 1956 2 Sheets-Sheet 2 Filed June 29, 1954 INVENTOR. J05! 0. FEELS/6 BY &

iTToR/VE REGULATED marl VOLTAGE SUPPLIES Joseph 0. Preisig, Trenton, N. J., assignor to Radio Corporation of America, a corporation of Delaware Application June 29, 1954, Serial No. 440,067

8 Claims. (Cl. 315-14) This invention relates generally to the regulation of voltage supplies and more particularly to novel improvements in the regulation of voltage supplies of the type suitable for satisfying the high voltage requirements of cathode ray tube electrodes.

It has become more or less a general practice in the monochrome television art to obtain the high voltage required for the final accelerating electrode of a receivers kinescope from a pulse type supply, in which high voltages are developed through rectification of the high amplitude, transient, fiyback pulses appearing in the receivers horizontal output transformer during retrace periods of the line scanning cycle, when cutoff of the horizontal output tube causes a sudden collapse of the magnetic field in the horizontal deflection yoke. Similarly, the development of high voltages for the final accelerating electrode, or so-called ultor electrode, of presently contemplated color kinescopes has been considered as calling for the use of such fiyback pulse type supplies. However, the high voltage requirements of a typical color kinescope are greater in magnitude, more critical as to regulation, and generally more demanding than the comparable supply requirements of a monochrome kinescope. It has thus been generally recognized that the ultor supply for a color kinescope requires the use of an active voltage regulating device to achieve the requisite stability of the supplied ultor voltage. The present invention is directed toward improved apparatus for, and methods of, regulating the high voltage supply of a color receiver to eliminate or substantially reduce certain deleterious effects which may result from variations in the supply output.

To more particularly appreciate the purposes of the present invention, as well as its form, a brief description of a conventional color kinescope ultor supply is in order. In a representative type of high voltage supply for a tri-color kinescope of the general type described in the article by H. B. Law entitled A Three-Gun Shadow-Mask Color Kinescope, appearing in the October 1951 issue of the Proceedings of the I. R. E., stepped-up fiyback pulses derived from the horizontal deflection wave output transformer are applied to the input electrode of a rectifier, which may take the form of a high voltage vacuum diode, for example. The rectifier delivers a charging current to a capacitor, connected between the output electrode of the rectifier and a suitable point of reference potential, in response to the periodic appearance of fiyback pulses. The D.-C. voltage developed across the charging capacitor is applied to the kinescopes ultor electrode, which may be directly connected to the rectifiers output electrode. Since the effective loading on the ultor supply will necessarily vary with picture content (i. e. with beam current), D.-C. regulation is generally required and achieved by shunting the space discharge path ofa regulator tube across the rectifier output circuit, and deriving an error or reference potential for the control electrode of the regulator tube 2,749,474 Patented June 5, 1956 ICC from a bleeder resistance, also shunted across the rectifier output circuit. In such supplies, the shunt regulator tube essentially functions only to effect D.-C. regulation, that is, only to remove relatively long term variations in the supplied ultor voltage. The regulator control circuit is essentially by-passed for shorter term, A.-C. variations in the supplied voltage, the charging capacitor being variations to the reference potential point.

The A.-C. variations in the supplied voltage may be considered as caused by two efifects, one being the residual 60 cycle ripple in the D.-C. output of the rectifier due to the use of periodic pulses as the energy source for the supply. To appreciate the other cause of A.-C. variations in the supply output, it must be recognized that a kinescope, while intended primarily as an image reproducing device, is also effectively a video signal amplifier, the ultor electrode serving as the anode for the video-modulated grid-controlled beam current. While appropriate choice of the value of the supplys filter capacitor may reduce the effect of video signal variations to relatively small percentage changes in the high voltage output, the expense of providing suitably insulated high voltage capacitors of high capacitance value introduces an economic factor which must be considered. In typical high voltage power supplies of the prior art, the value of the filter capacitor has been chosen, with an eye to this cost factor, of a value such that the capacitor presents a sutficiently low impedance to most video signal frequencies so that the output variations at these frequencies are relatively insignificant. At low video signal frequencies, such as frequencies of the order of the 60 cycle field scanning rate, however, the impedence of the typical ultor supply filter capacitor is sufficiently high that output variations of the order of several per cent are possible in response to the presence of video signal components of such frequencies in the beam modulating signal. While variations of such an order in the potential of the ultor electrode may be tolerable, another efiect which is less tolerable is also a result.

The other effect noted above is a beam rnisconvergence efiect, which results from the fact that where supplies of the type discussed above are used for tri-color kinescopes incorporating beam convergence apparatus of an electrostatic type, it has been the practice to derive the D.-C. (static) convergence voltage required by the kinescopes convergence anode from the aforesaid output bleeder of the ultor supply. The problems of beam convergence in color image reproducers are discussed in some detail in the article entitled Deflection and Convergence in Color Kinescopes by Albert W. Friend, also appearing in the aforementioned October 1951 issue of the Proceedings of the I. R. E. It may be appreciated by those familiar with beam convergence problems that the permission of the aforesaid low frequency A.-C. variations in the ultor supply voltage, appearing across the bleeder to which the convergence anode is coupled, will result in the application of undesired dynamic convergence voltage variations to the beam convergence anode. The re sultant rnisconvergence effects, while certainly not wholly destructive of the fidelity of the color image reproduction effected by the color kinescope, may be annoying and undesirable, and their elimination should result in the production of a more pleasing color picture.

As will be appreciated from the previous discussion, a reduction in these rnisconvergence effects may be achieved by increasing the capacitance value of the filter capacitor employed in the ultor-convergence supply, so asto more effectively short out the low video frequency signals. However, it will again be appreciated that achievement of a substantial elimination of these rnisconvergence effects in such a manner might involve a considerable added expense, as represented by the increase in cost of the high voltage capacitor utilized.

In accordance with the present invention, however, means for substantially eliminating these misconvergence effects are proposed, whereby such expense as involved in providing a filter capacitor of relatively high capacitance value is avoided. In accordance with embodiments of the present invention, such a result is achieved through utilizing the shunt regulator tube of the ultor supply for A.-C. regulation purposes as well as D.-C. regulation purposes. More specifically, the usual filter capacitor is supplanted by a capacitor of comparable value which couples the ultor voltage output to the control electrode of the shunt regulator tube so as to achieve a degeneration of the aforesaid video signal variations in the output. This capacitor, in series with the usual bias filter capacitor associated with the regulator tube, provides the requisite charging path for the ultor rectifier current, and achieves the filtering function normally effected by the filter capacitor which they supplant. The values of the two series capacitors are preferably chosen with respect to the resistance values of the portions of the bleeder which they shunt (i. e. the bleeder portions on either side of the regulator sampling tap) to provide substantially equal time constants, so that a constant ratio division of the AC. signals is effected at the regulator control electrode for all video signal frequencies. Elimination of rnisconvergence effects due to the coupling of video signal components to the convergence anode of a color kinescope via the output circuit of the ultor supply is thus achieved without increasing the cost of the conventional ultor supply.

Accordingly, it is a primary object of the present invention to provide a novel regulated high voltage supply.

It is an additional object of the present invention to provide novel means to eliminate misconvergence eifects in the operation of a color kinescope resulting from the ap pearance of video signal variations in the supply output from which the D.-C. convergence voltage is derived.

It is a further object of the present invention to pro vide a novel high voltage supply for a color lcinescope in which both short term and long term variations of the supply output are regulated out.

It is also an object of the present invention to provide a color television receiver with a novel and improved high voltage supply in which a shunt regulator tube eifectively functions as both a D.-C. and an A.-C. regulator.

Another object of the present invention is to improve the regulation of conventional high voltage supplies for a color kinescope without increase in the expense thereof.

Other objects and advantages of the present invention may be ascertained by those skilled in the art upon a reading of the following detailed desscription and an inspection of the accompanying drawing in which:

Figure 1 illustrates schematically a high voltage supply suitable for color kinescope purposes, in which regulation is achieved in accordance with prior art principles.

Figure 2 illustrates schematically such a high voltage supply as regulated in accordance with principles of the present invention.

Figure 3 illustrates the use of a high voltage supply in accordance with an embodiment of the present invention in a typical color television receiver.

Referring to Figure 1 in more detail, a high voltage supply of a type used prior to the present invention for supplying the ultor and convergence electrodes of a color kinescope is illustrated. High amplitude flyback pulses, appearing at terminal Z of a fiyback pulse source 11, which may comprise the horizontal deflection wave output transformer of the color receiver, are applied to the anode 14 of a diode rectifier 13. The cathode 15 of diode 13 is directly connected to the supply output terminal U, to which the ultor electrode of the color kinescope may be coupled, and is coupled to a point of reference potential (i. e. ground in the illustration) by a charging capacitor 17. A charging current is delivered by rectifier 13 to capacitor 17 in response to the periodic appearance of fiybaclt pulses at terminal Z, developing a DC. potential across capacitor 17 which is utilized by the aforesaid ultor electrode as its operating potential.

To eifect the requisite D.-C. regulation of the supply output, the space discharge path of a regulator tube, triode 19, is effectively shunted across the ultor supply output, the anode 21 of triode 19 being connected to the output terminal U and the cathode 25 being connected to the high potential terminal of a suitable B+ supply (not illustrated). An error or reference potential, for controlling the current in the space discharge path of regulator tube 19 in accordance with variations in the D.-C. voltage supplied to the ultor electrode, is applied to the control grid 23 of regulator 19 via its coupling to the adjustable tap of a potentiometer 32, which forms a series resistance portion of a high voltage bleeder 7.9, also shunting the ultor supply output. The D.-C. (static) convergence voltage required by the convergence anode of the color kinescopc (employing electrostatic convergence methods) is also commonly derived from the high voltage bleeder 29, as by coupling the convergence supply output terminal (1" to the adjustable tap of potentiometer 31 which forms another series resistance portion of the bleeder 29. It will be noted that in accordance with common practice, a bias filter capacitor 27 is coupled between the control grid 23 and cathode 25 of the regulator tube 19.

In Figure 2, application of the principles of the present invention to the prior art supply of Figure l is illustrated. Again, the anode 14 of rectifier 13 is connected to the terminal Z of the fiyback pulse source 11, and cathode 15 is connected to the supply output terminal The space discharge path of regulator tube 19 is again effectively shunted across the ultor supply output, and its control grid 23 is again coupled to the adjustable tap of potentiometer 32 forming a series resistance portion of the output-shunting high voltage bleeder 29. It will be noted, however, that the usual coupling of a capacitor 17 between the cathode 15 and a point of reference potential is not effected. instead, a capacitor 17 is coupled between rectifier cathode 15 and the control grid 23 of the rcgulator tube 19. The bias filter capacitor 27 is illustrated as being coupled between the control grid 23 and ground. It will be noted that the circuit of Figure 2 contains no additional circuit elements over those shown in Figure l. However, there are marked advantages to the use of the circuit connections illustrated in Figure 2 over the prior art connections illustrated in Figure l, which shall now be noted.

In the supply circuit illustrated in Figure l, the regulator tube 19 eiiectively functions only as a D.-C. regulator, overcoming relatively long term variations in the output voltages supplied. The charging capacitor 17 is intended to also serve as filter capacitor. effectively shorting video signals appearing at terminal U (due to the previously discussed video signal amplifying action of the color kinescope) to ground. As previously noted, however, unless a high voltage capacitor of relatively high capacitance value is utilized as capacitor 17, the filtering action of capacitor 17 is not too effective at the low end of the video signal frequency range. That is, the impedance of capacitor 17 at low video signal frequencies, of the order of the cycle field scanning rate, for example, is sutficiently high that significant variations in the supply output may occur. If the A.-C. variations are of the order of, say, two percent of the nominal ultor voltage value, such A.-C. changes in the potential of the ultor electrode may be readily tolerable. but a more serious result resides in the resultant variations in the voltage supplied to the convergence electrode of the color kinescope. Since the convergence electrode is coupled. to the ultor supply output via the high voltage bleeder 29, ultor voltage variations of the aforesaid. order result effectively in the application of an undesired dynamic convergence voltage waveform which may introduce significant misconvergence efiects. While suitable increase of the capacitance of filter capacitor 17 to a value at which its filtering action at the low end of the video signal frequency range is sufficient to reduce these misconvergence effects to a tolerable level is one solution, this is an unduly expensive solution in view of the manner in which the present invention proposes to eliminate such deleterious effects.

The solution as envisaged by the present invention and illustrated in Figure 2 is to utilize the regulator tube 19, already present in the circuit and performing a D.-C. regulating function, to degenerate or regulate out the aforesaid video signal variations. By capacitively coupling the video signals which appear at anode 21 to the control grid 23 also, such degeneration is effected. The capacitor 17, efiecting this desired coupling, may also serve, in series with the bias filter capacitor 27, to provide the charging path required for the ultor rectifier 13. It may be observed that the capacitors 17 and 27 efiectively provide a capacitance voltage divider for applying a predetermined fraction of the A.-C. signal variations to the control grid 23, similar to the D.-C. voltage division effected by the tapping of bleeder 29 for connection to control grid 23. The capacitance values of capacitors l7 and 27 are preferably chosen with relation to the resistance portions of the bleeder 29 that they shunt (i. e. R1 and R2, respectively) so that the time constants, R1 C17 and R2 C27 are substantially equal. With such a relationship, it will be appreciated that the ratio of the A.-C. signal variations applied to control grid 23 to the A.-C. signal variations appearing at terminal U will be substantially constant at all frequencies, the ratio corresponding to the D.-C. voltage division effected at the tap connection of control grid 23 to bleeder 29. It may be observed that in addition to effecting a degeneration of the video signals amplified by the kinescope, the A.-C. regulating arrangement of Figure 2 aids in degenerating ripple components which may inhere in the output of the rectifier 13.

Figure 3 illustrates a color television receiver including a high voltage supply which operates in accordance with the embodiments of the present invention discussed above.

The illustrated receiver is generally representative of presently contemplated color receivers for a simultaneous subcarrier type color television system in accordance with the revised FCC color standards, and is in general accord with the principles and apparatus discussed in the article entitled Principles and Development of Color Television Systems, by G. H. Brown and D. G. C. Luck appearing in the June 1953 issue of the RCA Review. Carrier waves modulated by a composite color picture signal are received by conventional signal receiving apparatus 61, which may include the usual R. F. tuner, converting apparatus, I. F. amplifier, signal detector, etc. The video frequency signals recovered from the modulated carrier in the receiving apparatus 61 are amplified in the video amplifier 63. Synchronizing information is derived from the recovered signals in the sync separator 65 and utilized to synchronously control the receivers subcarrier drive apparatus 67, to control the generation of vertical scanning waves in the vertical deflection circuits 69, and control the generation of horizontal frequency sawtooth voltage waves in the horizontal sawtooth wave generator 71.

Respective color mixture signals (e. g. narrow band E signals and wider band Er signals, discussed in detail in the aforementioned article) are recovered from the video signal output of amplifier 63 in respective color demodulator channels which include bandpass filters 75 and 77 of respectively appropriate passbands, synchronous demodulators 81 and 83 receiving respectively appropriate phases of the output of the subcarrier drive apparatus 67, and low pass filters 85 and 87 having the respectively appropriate narrow and wider responses. The receiver is also provided with a brightness channel, including a low pass filter 86 having the desired wide band response, through which the broad band monochrome portion of the composite picture signal may pass. The outputs of the brightness channel and two color channels are suitably combined in the matrixing circuits 89 of the receiver to obtain the simultaneous color sig nals which may be applied to appropriate beam control elements of the color image reproducer 40.

The color image reproducer 40 is illustrated schematically as one of the three-gun shadow-mask kinescope type. Color image reproducers of this general type are discussed in some detail in the aforementioned article by H. B. Law entitled A Three-Gun Shadow-Mask Kinescope. In a color image reproducer of this type, three electron beams are used, one for each primary color. The beams strike a phosphor screen composed of a regular array of red-, green-, and blue-emitting phosphor dots. Between the electron gun position and the phosphor screen there is placed a thin perforated metal sheet for the purpose of partially masking the electron beams. The phosphor dot array on the screen comprises a plurality of closely spaced phosphor dot trios, each trio consisting of a red-, green-, and blue-emitting phosphor dot with the centers of the dots lying at the corners of an equilateral triangle. The trios themselves lie at the corners of an equilateral triangle of larger size. Associated with each of the phosphor dot trios is a hole in the shadow mask, these holes also being located at the corners of an equilateral triangle. The three beams, disposed apart about the tube axis, are converged to a point on the mask by suitable static and dynamic beam converging means, the electron beam which is to contribute the red portion of the picture is prevented, by the mask, from striking those areas on the screen containing blue and green emitting phosphors. Likewise the green and blue beams can strike only the green and blue emitting phosphor dots, respectively. The target structure 51 of the illustrative color kinescope 40 may be considered to be of the general shadow-mask type above described.

As schematically illustrated, the three electron beams are developed and shaped in respective electron gun structures, each including a thermionic cathode 41, a control grid 43, a first anode or accelerating electrode 45, and a focusing electrode 47. The electron gun structures may be disposed symmetrically about the tube axis such as to produce three substantially parallel beams or may be inclined at respective angles to the tube axis so as to provide three beams substantially converging at a common point on the target.

A common convergence anode 49 is illustrated, which when energized by suitable dynamic convergence waveforms generated in the dynamic convergence waveform generator 56 along with an appropriate (static convergence) D.-C. component, serves to converge the three beams to a common point in the plane of the shadowrnask of target structure 51 throughout the scanning of the raster. The principles of multibeam convergence, and a description of typical circuits for developing dynamic convergence waveforms from sawtooth waves of field and line frequency may be found in an article by Albert W. Friend appearing in the October 1951 issue of the Proceedings of the I. R. E. and entitled Deflection and Convergence in Color Kinescopes. As illustrated, the beam convergence circuits may derive the respective sawtooth information from the vertical deflection circuits 19 and the horizontal output transformer 93, and convert these sawtooth Waves into essentially parabolic waveforms, as disclosed in the aforementioned Friend article, for combined application with a D.-C. component as suitable convergence waveforms to the common convergence electrode 49. Also, as indicated in Figure 3, the correcting waveform output of generator 56 may be applied, suitably modified in amplitude, to the focus electrodes 47 to maintain essentially optimum focus throughout the entire raster, as suggested in the Friend article. Beam alignment magnets 57, one associated with each of the three electron beams, may be employed to provide individual correction of beam misalignment, as disclosed in the aforementioned Friend article.

In addition to the beam controlling apparatus already described, the illustrated color kinescope 4t is also provided, as is generally customary, with a color purity yoke 54, applying a uniform transverse magncdc field to all the electron beams to orient the system of beams as desired. The yoke may comprise either a rotatable single pair of coils, or two fixed pairs of coils at right angles, fed from an adjustable source of D.-C. (as indicated on the drawing). The use of such a purity coil to deflect the three beams equally so that they may be adjusted to pass through their respective color centers is explained in greater detail in the aforesaid Friend article.

The kinescope is provided, as is conventional, with a final accelerating electrode, the ultor 50, which may take the usual form of a conductive coating on the inner surface of the lrinescope 46 extending from the vicinity of the convergence electrode 4? to the beam target structure 52. Where the flared portion of the kinescope envelope is itself a conducting metal, the conductive coating need only extend forward sufficiently to make electrical contact with the metal flared portion.

To effect deflection of the three beams to trace a scanning raster n the target structure 51., a deflection yoke 53 is provided with appropriately disposed hori Zontal and vertical deflection windings. The yoke 53 is illustrated as having vertical yoke terminals V--V, to which field frequency scanning waves developed in the vertical deflection circuits as are applied. The horizontal yoke terminals I-L-Ii derive line frequency scanning waves from the horizontal output transformer 93, energized by a current supplied by the horizontal output tube 91 to provide the desired scanning sawtooth in the horizontal yoke. The illustrated horizontal. output trans former 93 is of the autotransformer type, the cutout ot' the horizontal output tube 91 being applied across a selected portion of the total series of windings, and the horizontal yoke being effectively coupled across a smaller segment of this portion. The driving connection output tube 91 to the transformer $3 is illustrated as being at an intermediate point Y, while the yoke connections are illustrated at lower potential terminals R and on the transformer 93. The conventional danger tube 92 is illustrated as having its cathode connected to trans former 93 at point T. intermediate points S and Y," and its anode connected via a B-boost capacitor 94 to the low potential terminal R. Details of components and circuitry conventionally associated with yoke circuits, such as width and linearity controls, centering circuits, etc. have not been illustrated for the sake of simplifying the drawing.

The high voltage supply illustrated in Figure 3 as associated with the horizontal output transformer 93, in cludes a conventional focus supply arrangement. in which the focus rectifier Edi is coupled to an intermediate point X on the output transformer 3. The D.-C. output of rectifier Kill, appearing across the capacitor 103, is applied across the fixed terminals of potentiometer U35. The focus supply output terminal F, to which the focus electrodes 47 of itinescope 4% are coupled, is connected to a variable tap on potentiometer 195, so that adjustment of the voltage supplied to the focus electrodes may be made.

The ultor-convergence voltage supply arrangement illustrated in Figure 3 is in accordance with the embodiment of the invention illustrated in Figure 2. The anode 14 of the ultor rectifier 13 is connected to the high potential terminal Z of the output transformer 93. The

ultor supply output terminal U is connected to cathode 15 of rectifier 13. The space discharge path of regulator tube 19 shunts the output of ultor rectifier 13, and derives its D.-C. reference potential via the coupling of control grid 23 to the variable tap of the potentiometer 32 portion of a high voltage bleeder 29, also shunting the ultor rectifier output. The convergence supply output terminal C, to which the convergence anode 49 is coupled, is connected to the variable tap on the potentiometer 31 portion of bleeder 29.

in accordance with the principles of the present invention as previously discussed, the capacitive charging path for rectifier 13 is provided by a series connection of capacitors 17' and 27' between terminal U and ground. The regulator control grid 23 is connected to the junction point between capacitors 17 and 27.

To review the advantages noted for this arrangement of the regulated ultor supply, it may be noted that video signal variations which appear at terminal U, and would otherwise tend to adversely affect beam convergence, are effectively degenerated by the action of regulator tube 19 due to the capac' ive coupling betwee. control grid 23 and terminal U. By appropriate proportioning of the values of capacitors 17 and 27, a satisfactory degree of degeneration may be achieved for all video frequencies. Degeneration or ripple components in the pulse rectifier output is also effected. The 2vvantageous performance thus outlined may be achieved without requiring additional tubes or circuit elements over those used in prior art supplies 01? this general type.

Having thus described my invention, what is cla' ned is:

1. In a color television receiver including a color kinescope comprising an ultor electrode, a high voltage supply .com-prising in combination a rectifier having an output circuit, means for coupling said ultor electrode to said output circuit, an electron discharge device having a space discharge path and including a control grid, said space discharge path effectively shunting said output circuit, and means for capacitively coupling said ultor electrode to said control grid.

2. A high voltage supply in accordance with claim 1 including a bleeder resistance also shunting said rectifier output circuit, and means for adjustably coupling said control grid to said bleeder resistance.

3. In a cathode ray tube system including a cathode ray tube device comprising an ultor electrode, a high voltage supply comprising in combination a rectifier having an output electrode, means for connecting said ultor electrode to said output electrode, an electron discharge device including an anode, a cathode and a control grid, means for connecting said anode to said output electrode, means for connecting said cathode to a point of reference potential, a capacitor, and means for coupling said capacitor between said control grid and said ultor electrade.

4. A high voltage supply in accordance with claim 3 including a resistance, means for connecting said resistance between said ultor electrode and a point of reference potential, and means for connecting said control grid to an intermediate point on said resistance.

5. A high voltage supply in accordance with claim 4 including an additional capacitor, means for connecting said additional capacitor between said control grid and said point of reference potential, the ratio of the capacitance value of said first-mentioned capacitor to the capacitance value of said additional capacitor being substantially equal to the ratio of the ohmic value of the pontion of said resistance extending between said intermediate point and said point of reference potential to the ohmic value of the portion of said resistance extending between said intermediate point and said ultor electrode.

6. A voltage supply comprising in combination an energy source, a rectifier having an input circuit and an output circuit, an output terminal, means for coupling said input circuit to said energy source, means for coupling said output circuit to said output terminal, a regulator tube including a space discharge path and a control grid, means for shunting said space discharge path across said output circuit, a resistive voltage divider also shunted across said output circuit and including an intermediate tap, a capacitive voltage divider also shunted across said output circuit and having an intermediate terminal, and means for connecting said control grid to both said intermediate tap and said intermediate terminal.

7. In a color television receiver including a color kinescope comprising an ultor electrode and a convergence electrode, a high voltage supply comprising in combination an ultor rectifier having an output electrode coupled to said ultor electrode; :an electron discharge device having l3. space discharge path shunted across the output of said ultor rectifier and including a control electrode; means for utilizing said discharge device as a D.-C. regulator, said utilizing means comprising a high voltage bleeder also shunted across said ultor rectifier output, and means for adjustably coupling said control electrode to an intermediate point on said bleeder, said convergence electrode being coupled to a second intermediate point .On said bleeder; .and means for additionally utilizing said discharge device as an A.-C. regulator, said additional utilizing means comprising a capacitor, and means for coupling said capacitor between said control electrode and said ultor electrode.

8. A high voltage supply in accordance with claim 7 including means for rendering the A.-C. regulating performance of said discharge device essentially independent of frequency, said latter means including an additional capacitor, and means for coup-ling said additional capacitor between said control electrode and a point of reference potential, the sum of the capacitance values of said additional capacitor and said first-mentioned capacitor bearing essentially the same relationship to the capacitance value of said first-mentioned capacitor as the voltage appearing across said bleeder bears to the divided voltage appearing at said first intermediate point of said bleeder.

References Cited in the file of this patent UNITED STATES PATENTS 2,215,766 Barnard Sept. 24, 1940 2,237,649 Blurnlein et 'al. Apr. 8, 1941 2,276,455 Beers Mar. 17, 1942 2,352,988 Wilcox July 4, 1944 2,493,600 Seaward Jan. 3, 1950 2,523,108 Friend Sept. 19, 1950 2,599,798 Wissel June 10, 1952 2,621,305 Little et al. Dec. 9, 1952 2,655,615 Seldin Oct. 13, 1953

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