US2665393A - Deflecting and high voltage supply circuit - Google Patents

Description

Jan. 5, 1954 c. v. BocclARELLl DEFLECTING AND HIGH VOLTAGE SUPPLY CIRCUIT 2 Sheets-Sheet l Filed Sept. 6,

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om@ y. 50x/maw' AGEN/f Jan. 5, 1954 c. v. BocclARELLl DEFLECTING AND HIGH VOLTAGE SUPPLY CIRCUIT Filed sept. e, 195o 2 Sheets-Sheet 2 Patented Jan. 5, 954

nEiLcTING AND HIGH VOLTAGE SUPPLY CIRCUIT Carlo V. Bocciarelli, Philadelphia, Pa., assignor to Philco Corporation corporation of Pennsyl Philadelphia, Pa., a. vania Appiicati'o september 6, 195o, serial No. 183,395

6 claims. (c1. 315-27) l ode-ray tube. In such arrangements according.

to the` prior art, the fraction of thevtotal energy supplied by the deiiecting signal source,ywhich was required by ,Y thehigh-potential rectifying circuit ,was invariably@r relatively small iraction (e. g. 10%).. This `was'largely due to the( fact that the deecting'yokes commonly used in such circuits were of relatively low eliciency. v

In such circuits it was customary to employ a conventional closed-core transformer for transferring energy from .the `deflecting signal source to both the deiiectirig'V yoke and the highvoltage rectifyirig circuit. Such a` transformer functioned initially to transfer substantially all of the energy from the deflectingsignal source to` tliedeflecting yoke'. l During the return ofthe cathode-'ray beaml fromf-the end of onevlineto th'begi'nnin'g of the next, a relatively small portion vof this energy,'which was stored in the eld surrounding thedeilecting yoke, was returned through the transformer to the high-voltage rectifyingcircuit. v k

Recently there have been developed delecting yokes of much higher eiiiciency, such, for example,l as the one described and claimed in my copending'application Serial No. 164,465, led May 26,1950, in which the windings of the yoke are disposed at all points in close proximity to the path of the electron beam so as to exert the maximum force tendngto deflect the beam at all points along' its path, whereby the maximum possible deflection of the beam is eiected in response to a minimumof deectng energy.

vWhen such a high efficiency yoke is employed in" a combination deecting and high-voltage supplycircuit of the sort above referred to, the fraction ofthe total energy supplied bythe deflecting signal source which goes to the high.

voltage rectifying circuit` is substantially in-A creased (e. g. to as muchas 30%) by reason of the reduction in the energy requirements of theY defiecting yoke. It Ilwas, found in practice however, that the advantages" of increased eiiciency of -such yokes could not berealilzed in a Icombination deecting and hgl-'voltageV circuit coni' 2. structed in accordance withthe prior art.V Further it appearedthat such an arrangement tend-.- ed to provide too` higha delectingcurrent in the yoke, while at the same time developing an in.- sufciently high potential for second anode sup.

ply purposes. Upon investigation of lthis situation it appeared that the diiculty lay in the con.- ventional form of transformer, whichwhile it op,-v erated efciently to transfer energy from the de-Y ecting signal source `to the `deilecting-v yoke, failed to permit the supply of a sucient'fraction ofthedeflecting energy to the high-voltage rec,-`

tifying circuit. Thus if this transformer were cle.

signed to supply the right amount of power to the deecting yoke, then` an insuiiicientamount of power would be supplied to the high-voltage rectifying circuit, while,` on the other hand, if.

it were designed to supply sufficient power to the high-voltage rectifying circuit, then an unnecessarilylarge amount of energy wouldbe sup--V plied to the deflecting yoke. Further it was noted that, since all of the energy from the delecting signal source was initially supplied to the deecting yoke and ,a portion of it later returned` through the transformer to the high-voltage rectifying circuit,` arsubstantial loss4 (eg. as much as 20%) resulted fromthis yunnecessary transfer ofV energy from the deectingv signal source t0 the deflectingyoke and then from the delecting yoke back to the high-voltage rectifying circuit.Y

`Accordingly it is, the primary object of the lin- Vention to overcome;v theaforementioned di-'f culties and to provide a combined deliectng and high-voltage supply system for cathode-ray tubes, Y 'in which botha cathode-ray beam deflecting yoke and a high-voltage. second anode supply*L circuit, whose energy requirements constitute` a relatively large` fraction ofthe total energy `sup` plied to bothsaid yoke and said high-voltage circuit, are energized from a common source'ofV del-Vv fiecting signal, and inV which energy is suppliedfrom said common source to saiddeecting yoke and said high-voltage supply circuit n proportion to theirrespective requirements and with maximum efliciency. f Ihave -discoveredthat this objective can be' plied by the deflecting signal source tobe-stored 1n the field surrounding Vthe transformer, said portionbeing substantiallyequal to the portion of the total supplied energy which is required by ,ransferred to the high-voltage rectifying cirg- In contradistinction to the mode of operai of the prior art arrangement, lthe portion energy supplied from the deliecting signal rce to the high-voltage rectifying circuit is plied directly from the source to the rectifycircuit without an intermediate transfer to deflecting yoke and back again. Hence the :es inherent in the prior art arrangement areV iinated and maximum efficiency is insured. further feature of the arrangement in acdance with the present invention lies in the t that the open-core transformer employed rein not only provides for the proper dis- Jution of energy between the deecting yoke l the high-voltage rectifying circuit to cause im to operate properly and to insure the deed overall high efficiency, but is also substanlly cheaper and more readily manufactured n the conventional closed-core type employed prior art arrangements. )ther objects and advantages will be apparent m the following description of a preferred 'n1 of the invention and from the drawings, which: Figures l and 2 are graphs of anode potential :sus deection energy, showing the manner in lich these two factors vary for different types cathode-ray tubes and for different deecn angles; Figures 3 and 4 are perspective views of a prefred type of coupling transformer for use in `evision deflection and H.V. circuits designed accordance with the present invention; and Figure 5 is a schematic diagram of one form cathode-ray beam deflection circuit designed accordance with the present invention and iploying the transformer of Figs. 3 and 4. In order to comprehend fully the advantages a deflection and high-voltage circuit of the ,ture set forth in the present disclosure, it is ilpful to consider the manner in which the `Werrdeveloped in a television deflection circuit utilized by different types of cathode-ray tubes. will be sufficient for the purpose of the present ustration to consider four cathode-ray tubes, ie of which is a standard, or conventional, tube wing a 55 deflection angle, the second of which a similar tube having a 70 deflection angle, ie third of which is a 55 narrow-neck tube :signed in accordance with the principles set .rth in applicants copending case above-menoned, and the last of which is another narrowack tube with a '10 deflection angle.

Considering first the 55o standard tube, there shown in Figure 1 a curve of the energy which Lay be supplied to this tube for deflection, versus ie high voltage, or anode potential, developed t any particular deflection energy value. It will e observed that the relationship takes the form f a straight line the lower portion of which Within the anode potential region of approxilately 8 to 10 kv.) corresponds to a domain lhere a standard 10 tube of this type might e operated. The above portion is followed, for

iigher anode voltages, by a similar one charac- 4, teristic of a 12" tube, then one of a 16" tube, and so on. The linearity of the curve is primarily due to the fact that any increase in defiection current (for an equal deflection angle) is proportional to the square root of the anode potential, and hence the deflection energy (which may be expressed as l/g Li2) is directly proportional to the high voltage. In practice, various circuit losses will cause the curve to depart slightly from a perfectly linear condition.

The other curves of Figure 1 similarly indicate theV anode potential versus deflection energy relationship for the other tube types mentioned above. It will be noted in this connection that, the more efficient the tube type, the steeper the slope of the line which represents it. Furthermore, while the narrow-neck 55 and '70 tubes may be deflected by Va B+ supply of approximately volts, the standard 55 normally requires 250 volts, and the standard 70 in the neighborhood of 330 volts.

It may readily be seen from Figure l that with a power input of, say, 19 watts, the standard 70 tube may be supplied with about 11/4 millijoules of deflection energy, and hence the maximum anode potential which can be developed is in the neighborhood of 6 kilovolts. With the narrowneck '70 deflection angle tube, however, almost as much deflection energy is obtained from the same input, while the high voltage is increased to nearly 12 kv. when using a transformer of the type to be later described.

Figure 2 is a graph showing the number of driver tubes, vand the value of B+ power supply, required for cathode-ray tubes of the types now being considered. For example, with a single GBQS driver tube, and a B+ supply of volts, approximately one millijoule of deection energy is produced for a standard '70 cathoderay tube together with approximately 4 kv. of anode potential. With a narrow-neck 70 tube, and using the transformer of the present application, nearly as much deflection energy is developed, while at the same time the high voltage output is raised to approximately 8 kv., or nearly double the amount. Other relationships are apparent from an inspection of the graph. However, a portion of the data which is available therein may be summarized in the following table:

It will be noticed that the graph of Figure 2 may be roughly divided into three Zones. The first is a region utilizing the transformer described in the present application, the second is a section lying closer to the 1/2 Li2 axis where a transformer with a closed core is normally required, and the third is an intermediate region where not only a closed core transformer but also a voltage doubler would probably be necessary and which includes a large majority of the standard cathode-ray tubes now known in the art. It is of course apparent that each location lying progressively further from the origin will require progressively larger power output tubes for satisfactory operation.

accuses Referring now to Figures 3 andl 4 of the drawings, there is shown a preferred form of coupling, or output, transformer designed for use-in a circuit according to the present invention; This transformer, generally indicated by the reference numeral I0, includes a core member I2 composed of some suitable finely-dividedv ferromagnetic material, such as powdered iron, in combination with a binder. The core member I2 (which may also be called a slug) is of generally cylindrical form, and is enclosed within an insulating tube ifi Iwhich serves as a support upon which a plurality of coils are wound.

As hereinbefore pointed out, the configuration and dimensions of this core are chosen so as to provide an air gap in the magnetic flux path linking the windings of the transformer which issuciently large to causea portion of the total energy supplied by the deecting signal source to be stored in the held surrounding the transformer, said portion being substantially equal to the portion of the total supplied energy which is required by the high-potential rectifying circuit. Under these conditions the impedance of the transformer looking into the terminals to which the yoke is connected is small compared to the yoke impedance. In the circuit for which the present transformer was designed, the requirement of the deecting yoke was 9 watts, while that of the high-voltage supply circuit was 3 watts. The procedures involved in designing a core to satisfy this requirement are well understood by those skilled in the art of magnetic circuit and transformer design, and therefore need not be discussed in detail in this specification. Sumce it to point out that, in the present instance the length of the core satisfying this requirement is substantially equal to the longitudinal distance measured along the core axis which is occupied by the various windings associated therewith.

The insulating tube Ill is positioned by a U- shaped mounting bracket I6 having a pair of anges I8 and 2li to which the ends of the tube Iii vare respectively secured by means of removable rivets 22, the flanges I8 and 2G being curved in such a manner that the tube I4 is eifectively cradled therein. The entire assembly may be bolted vto a television chassis or other apparatus through openings Z formed in the lower portion of the bracket Iii.

A pair of concentric coil windings 26 and 28 are supported by the insulating tube I, the coil 26 being laid down next to the tube so that it encircles the core member I2, and coil 28 being wound upon coil 26 in the general form of a disc which lies midway between the ends of the latter.

Adjacent to the coil 25 is a further coil 30, these two windings being separated by an insulating spacer 32. The coil 30, as best shown in Figure 3, may consist of not more than two or three turns of wire loosely wound on the tube It.-

While three coil windings have been shown in the drawings, it will be appreciated that the number of such coils employed will depend upon the use to which the transformer IEB is to be put. For example, the coils 2S and 28 may represent portions of an auto-transformer for the horizontal deflection circuit of a television receiver employing a surge-type rectifier, while the coil 3G may represent the rectifier heater winding. However, it should be clearly understood that the numberand arrangement of the coils themwith the 6, selves forms no speclc Vpart of-'thelpresent in# vention, and that numerous otherV winding ar-y rangements may be usedif desired Yin-place' of the one illustrated.

Mounted on one of the side'members of the bracket I6 is a terminal board 34 having a cen-- tral aperture through which projects one end 'of the insulating tube I4, as well as the ange 20 to which that end of the tube I4 is attached by the rivets 22. This construction is-best shown in Figure 4. Additional rivets 36 secure ther terminal board 3ft to the support I 5.-

Terminal board 34 is provided with a number of connectoi` lugs A,'B, C, D and E. When the transformer Iii is utilized as a coupling element in a horizontal deection circuit of the type shown in Figure 5,'then the lugs A and E are ree spectively joined to the ends of the winding-26friShis permits the anode of a power output tub to be connected to the terminal E, and the posi--V tive terminal of the B-I- supplyto be connected to 'f the terminal A either directly or through a socalled boost condenser as shown in the drawing.

Accordingly,

nected to one end of an adjustable ywidth-control lnductor the other end of which is joined to vterminal A. A pair of high-efficiency deiiectioncoils are connected across the terminals A and C.

These may be of the sort described and claimed in my aforementioned copendingv` application.

Winding 28, which is the high-voltage, orstep-'up,- winding of the transformer It, hasitshighvoltage end shown in Figure 5.' It

ture of these terminals will depend upon thedesign of the particular circuit-in which the trans'- former I is to be employed.'-

The performance and eiciency ofthe trans--v former It depends in material composing the cylindrical core I2.

that another characteristics plish this transformer, constitutes an extension of one of the bers of the bracket I5. y sulating tube I being partially cut away in Figure 3 in order clearly to tion) projects through aniopeningi di? formed in the tube IIS in such cylindrical core lies flat against core. A

However, when it is desired to remove the core I2 for replacement or other reasons, the

may be used. Inorder'to accom'- side mem# rivets 22 are extraetedffrom'that end of the transformer. This permits a separation of the tube it and the flange I8, the prong 38 withdraw--v Since the prong is le. Following the insertionl ofanothe'rcore ele ment, thetube I t' is again'broug'ht'inconta tlf' iange I8 and the@rivetsZ-i-reisertedi Lugs B, C and D respectively representtaps on the winding 2Q, as also indicated bythe the cathode y connectedfto a'ter'minal F onvv the board 3d, to which point a cable 36 is also soldered f` or otherwise securely attached. This-cableleads to the anode of the high-voltage rectifier' tube will of course be apparent` that whereas a specie number of terminals `orf` lugs have been illustrated as beingmounted on: the panel 3e, nevertheless the number and 'na-Y part upon the nature of` Itum may be desirable at times toV removev thel core'so* one havingl different operating"v without completely disassembling the there is provided prong 38 which This prong 38 (the inv-- bring out this construcf a:manner that, when thev 2- is* in position',` the `prong .38' one ofthe end' surfaces of `the M nough such replacement means is only neces-- y at one end of the transformer, it may obusly be employed at both ends if found necesy or desirable. The high-voltage winding 28 is provided with elatively large number of turns as compared a, standard transformer. Normally this would an that the retrace portion of each scanning le would be increased to a prohibitive degree. the case of the transformer as described in the :sent application, this undesirable increase in race time is not present due to the looser coung between the turns of the winding which rets from the relatively small amount of core ,terial employed. Thus it is possible to achieve high-voltage output `from the transformer, ile at the same time maintaining the inverse ,tage on the damper-tube and the direct kick the power tube comparatively low. This simes circuit design and permits cheaper power )es to be utilized. If it is found that the relaely loose coupling between turns of the highltage winding causes a tendency of the transrmer to rng, this tendency can be almost :npletely overcome by slightly increasing the eicient of coupling between turns by the use Wire having a slightly higher degree of resistce. For example, if iine magnetic wire is subtuted for the usual copper wire, the coeflicient coupling will be increased, while at the same ne the circuit losses will not be appreciably eater since the current drawn by the cathodey tube does not normally exceed 10-4 amperes. the same time, the use of cheaper iron wire rther reduces the cost of the transformer. Another advantage obtained through the use a transformer constructed in accordance with le showing of Figures 3 and 4 is that the highltage winding 28 has a relatively low capacince t ground. This is due principally to the )sence of a closed core, since, when such a `ember is used, its proximity to the high end the step-up winding reduces the L/C ratio of le transformer and undesirably increases the ,'oportion ofeach deflection cycle that is reiired for retrace. Inasmuch as only a single slug is employed in the transformer of the :esent disclosure, there is no iron mass near the righ end of the winding 28, and hence the .inimum snap-back time is determined in factice mainly by the reactance of the remain- Lg components of thedeflection circuit.

The absence of a closed core in the trans- )rmer has a still further advantage over conentional designs in that the danger of arcing etween this element and the H.V. winding 28 a effectively eliminated. This introduces a fac- )r of safety into the deflection circuit thatV 'ould not otherwise be obtainable.

Although the assembly of Figures 3 and 4 has `een shown to include only a single high-voltage ectier heater winding 30, it is obvious that the Lumber of such windings depends upon the numler of high-voltage rectifier tubes which are ltilized.

Further it is to be understood that, while the pecic transformer herein described for use in circuit according to the invention is of the crm commonly referred to as an autotrans- 'ormer, the invention is not limited to the use )f such a transformer. On the contrary, Kif desirable other forms of transformers, such as -hose having separate primary and secondary windings may be utilized.

Having thus described my invention, I clamf 1. In a combined deiiecting and high-voltage supply system for cathode-ray tubes, a source of deecting energy, a cathode-ray beam deflecting yoke and a circuit for rectifying a portion of said deiiecting energy to provide a high potential for supplying the second anode of a cathode-ray tube, the energy required by said high-potential rectifying circuit constituting a relatively large fraction of the total energy supplied by said source to both said yoke and said rectifying circuit, and an open-core transformer having input terminals connected to said source and having output terminals connected respectively to said .defiecting yoke and said rectifying circuit and serving as an energy transfer device supplying .energy from said source to both said deflecting yoke and said rectifying circuit, the core of said .transformer having an air gap suiliciently large .to cause a portion of the total energy supplied Iby said source to be stored in the field surrounding said transformer, said portion being substan- .tially equal to the portion of the total supplied energy which is required by said high-potential lrectifying circuit.

2. A combined deflecting and high-voltage supply system according to claiml in which said transformer is provided with a common winding to which are connected both the input terminals .and also the output terminals associated with the said deflecting yoke, said transformer in addition 'being provided with a further Winding, constituting an extension of said common winding, to which is connected the output terminal associated with the said rectifying circuit.

3. A combined deflecting and high-voltage supply system according to claim 2, wherein the wire of which the said further winding is composed has a higher coefficient of resistance than the wire comprising the said common winding.

4. A combined delecting and high-voltage supply system according to claim 1 in which said .transformer is provided with a plurality of windings arranged to overlie the said core, the conguration of the latter being such that it is substantially completely contained within the space occupied by the said windings.

5. In a combined defiecting and high-voltage supply system for cathode-ray tubes, a source of energy, a'cathode-ray beam deflecting yoke having a given impedance and a circuit for rectifying Ia portion of said energy to provide a high potential for supplying the anode of a cathode-ray tube, the energy required by said high ypotential rectifying circuit constituting a relatively large fraction of the total energy supplied by said source of both said yoke and said rectifying circuit, and an open core transformer having input terminals connected to said source and having output terminals connected respectively to said deflecting yoke and said rectifying circuit, said .transformer serving as an energy transfer device for supplying energy from said source to both said deecting yoke and said rectifying circuit, said transformer exhibiting at the output terminals thereof connected to said deflecting yoke an impedance value smaller than the impedance .value of said deflecting yoke, the core of said transformer having an air gap sufficiently large to cause a portion of the total energy supplied lto said transformer by said source to be stored in the magnetic eld surrounding said transformer, said portion being substantially equal to the portion of the total supplied energy which CARLO V. BOCCIARE-LLI.

References Cited in the file of this patent UNITED STATES PATENTS Number CII Name Date Lyman Mar. 26, 1946 Foster June 8, 1948 Schlesinger Jan. 11, 1949 Torsch May 17, 1949 Clark Jan. 2, 1951 Schwarz Feb. 27, 1951

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