US3162791A

US3162791A - Width controlling means for cathode ray tube displays

Info

Publication number: US3162791A
Application number: US256459A
Authority: US
Inventors: Gostyn Ernest
Original assignee: Arris Technology Inc
Current assignee: Arris Technology Inc
Priority date: 1963-02-05
Filing date: 1963-02-05
Publication date: 1964-12-22
Anticipated expiration: 1981-12-22

Description

Dec. 22, 1964 E. GOSTYN 3,162,791

WIDTH CONTROLLING MEANS FOR CATHODE RAY TUBE DISPLAYS Filed Feb. 5, 1963 2 Sheets-Sheet l INVENTOR. fen 52" 6057/ E. GOSTYN Dec. 22, 1964 WIDTH CONTROLLING MEANS FOR CATHODE RAY TUBE DISPLAYS 2 Sheets-Sheet 2 Filed Feb. 5, 1963 FIG. .9

INVENTOR.

[PA/55f aayrm/ Af/a/PA EXJ current in the horizontal deflection windings.

United States Patent 3,162,791 WHDTH @GNTRQLHNG MEANS FUR CATHQDE RAY TUBE DKSPLAYS Ernest Gostyn, Longrneadow, Mass, assignor to General instrument (Corporation, Newark, Ni, a corporation of New Jersey Filed Feb. 5, W63, Ser. No. 256,459 16 Claims. (Cl, 317--2tl) The present invention relates to means adapted to be used in conjunction with a cathode ray tube in order to control a single dimension of the display, and without deleterious effects on the desired shape (usually rectangular) 0f the display.

In a cathode ray tube display, such as that used for television reception, a beam of electrons is scanned laterally and vertically, thereby to sweep over that area of the screen where the display is to be produced. Because of the diiferent characteristics of the horizontal (width) sweep, and the vertical (height) sweep, the means employed for controlling the extents of each sweep, and thus controlling the width and height respectively of the picture display, should vary. Control of the extent of vertical sweep (height) is comparatively simple. However, control of the extent of horizontal sweep (width) generally presents more of a problem, particularly because of the rapidity with which that sweep must be carried out, it being necessary that a large number of horizontal sweeps (usually in excess of two hundred) be carried out in the period of time required for a single vertical sweep.

In most instances the electron beam is swept by means of magnetic fields passing through the neck of the tube and generated by windings mounted on the exterior of the tube. These windings generally comprise two sets of coils, one for controlling horizontal sweep and the other for controlling vertical sweep, these two sets of coils being designated as horizontal and vertical deflection coils respectively. They are generally assembled on a specially designed support of insulating material so as to define a separately manufactured unit which can be increase in the width, the horizontal sweep circuit would have to work harder because of the line voltage increase, and would also have to work harder because of the additional loading engendered by the action of the reactor in compensating for the increase in line voltage. It is to be noted that increased loading efifect derived from the reactor is due not only to the fact that the reactor itself has losses, but also the fact that the introduction of the reactor into the circuit adversely changes the transformation ratio of that circuit.

An alternative to the variable reactor is the use of a metallic conductive sleeve which is introduced into the magnetic field, usually in the cylindrical space between the glass neck of the picture tube and the deflection yoke assembly. The eltect of this sleeve is electrically similar to that of the variable reactor-it affects the current in the horizontal deflection circuit. It does so by acting as a shorted secondary turn, eddy currents being induced therein, those eddy currents in turn reacting upon the Hence use of such a metallic sleeve will, like the variable reactor, increase the loading on the horizontal deflection circuit.

termed windows.

Patented ec. 22, 1964 In addition, the existence of the eddy currents generates heat which may lead to failure of the deflection assembly.

Because of the complex requirements on both the horizontal and vertical deflection fields, as well as the geometry of the display tube itself, a tendency exists on the part of the display even in the absence of attempts at width control, to depart from accurate rectangularity. More particularly, the display tends to be larger at the corners than elsewhere, giving rise to what has been very aptly termed pin cushion effect. In order to minimize this effect compensating magnets are often employed. Since these compensating magnets are usually fixed in position and in strength in order to produce optimum eliect for a given magnitude of the fields which produce horizontal and vertical deflection, any modification of the deflection field so as to control the dimensions 'of the display is often accompanied by an increase in undesirable pin cushion effect, even when only the horizontal deflection current is modified.

It is the prime object of the present invention to provide a method for controlling, either in fixed or adjustable fashion, a single dimension of the display (usually the width) in a simple and inexpensive manner, and in such a way as to avoid the disadvantages inherent in the prior art approaches to the subject as summarized above.

'More particularly, the arrangement of the present invention provides for width control Without increasing the loading on the horizontal deflection circuit to any appreciable extent. Moreover, the arrangement of the present invention lends itself readily to simple modification in order to minimize, and in some cases largely eliminate, pin cushion effect.

The structure of the present invention is specially designed to be used with a deflection winding which has axially extending conductor lengths connected by end turns, the Winding being formed in two diametrically opposed coils each having two axially extending conductor lengths circumferentially separated from one another by an appreciable space. Each of the axially extending conductor lengths of a given coil may be located circumferentially adjacent to axially extending conductor lengths of the other coil. This type of coil arrangement list typified by the so-called saddle windings. The spaces between the circumferentially inner peripheral edges of the adjacent conductor lengths of the two coils are here termed the butt sections of the winding. The spaces between the circumterentially inner edges of the twoseparated conductor lengths of each coil are here There are two butt sections and two windows for each pair of coils.

In accordance with the present invention control of the extent of the deflection caused by a winding of the type described is achieved by locating, substantially completely inside each butt section of the widing, a segment formed of high permeability magnetic material. These segments may be quite thin, and therefore may be conveniently interposed between the Winding in question and the neck of the tube on which the deflection yoke together with its windings is mounted. These magnetic segments act as magnetic shields or shunts which by-pass some of the magnetic field generated by the horizontal windings, thus reducing the amount of the generated field which is rendered efiective upon the electron beam for deflection purposes. When the segments are, as described, located substantially completely circumferentially inside the butt sections of the winding groups with which they are related, they will have a maximum etfect upon the horizontal deflection field, and will have no significant effect upon sociated with a given winding group is formed of a plurality of circumferentially separated sections, width control is achieved and at the same time the tendency of the overall display to assume pin cushion shape is minimized to a significant extent.

To the accomplishment of the above, and to such other objects as may hereinafter appear, the present invention relates to a structure for controlling deflection in a single direction in a cathode ray tube or the like, as defined in the appended claims, and as described in this specification, taken together with the accompanying drawings in which:

FIG. 1 is a side elevational View of a deflection yoke assembly embodying the present invention and providing for adjustable control of width;

FIG. 2 is a cross sectional view taken along the line 22 of FIG. 1;

FIG. 3 is a cross sectional view taken along the line 33 of FIG. 2;

FIG. 4 is a three-quarter perspective view of the adjustable element shown in FIGS. 1-3;

FIG. 5 is a view similar to FIG. 4, but showing a specificially different adjustable element;

FIG. 6 is a front elevational view of a deflection yoke assembly in which the present invention is embodied in a fixed and non-adjustable form;

FIG. 7 is a detailed cross sectional view taken along the line 7-7 of FIG. 6;

FIG. 8 is a side elevational view of a deflection yoke assembly similar to that of FIG. 6 but having a difierent type of vertical deflection winding thereon; and

FIG. 9 is a schematic cross sectional view of a typical deflection yoke assembly, such as that of FIG. 1.

In FIGS. 1-3 is disclosed a deflection yoke assembly comprising an insulating support generally designated 2 which is adapted to be mounted on the neck of a television tube. The horizontal windings, generally designated 4, are mounted on the interior of the support 2, while the vertical windings d are mounted on the exterior thereof. A magnetically permeable ring 8 surrounds the axially extending portions of the vertical windings 6, and is held in place by a clamp 10. The horizontal windings 4 are of the saddle type, and comprise two coils or groups of

Winding

4A and 4B. The coil 4A comprises axially extending conductor lengths 12 connected by end turns 14 while the coil 43 comprises axially extending conductor lengths 16 connected by end turns 18. The circumfertially outer edges of the groups of conductor lengths 12 I and 16 of the

coils

4A and 4B respectively are located close to one another at 20 (see FIG. 2), but the circumferentially inner edges of each pair of conductor lengths 12 and each pair of conductor lengths 16 are respectively circumferentially separated from one another by appreciably wide spaces 22. Those areas comprehended by the adjacent pairs of

conductor lengths

12 and 16 are here denominated the butt sections of the windings, while the spaces 22 between the butt sections of a given

coil

4A or 4B are called windows.

In the form shown in FIG. 1-3, the vertical winding 6 is also of the saddle type, in that respect being similar to the horizontal windings 4, and is, as illustrated, mounted on the exterior of the insulating support 2. The horizontal and deflection windings 4 and 6 are in space quadrature with one another.

The deflection yoke assembly as thus far described is essential conventional. The horizontal windings 4 and vertical windings 6 are separately energized, and each produces a magnetic field at right angles to the field produced by the other, and extending across the neck of the display tube on which the assembly is mounted, those fields controlling the horizontal and vertical deflection respectively of the electron beam which passes through the In accordance with the present invention, a pair of

segments

24 and 26 of high permeability ferro-magnetic material, preferably having low loss characteristics, are located inside the

horizontal windings

4A and 4B in such a position as to have parts extending in the same direction as the magnetic field produced by those windings. Reference may here be made to FIG. 9, in which the broken lines 23 represent the magnetic lines of force of the field generated by the

horizontal windings

4A and 4B. t will be noted that the

segments

24 and 26 respectively extend across each adjacent pair of groupings of winding lengths I2 and 16, are substantially completely circumferentially received within the confines of the butt sections of the

windings

4A and 4B, and do not extend circumferentially into the windows 22 defined between each adjacent assemblage of

winding lengths

12, 12 or 16, 16. Hence it will be apparent that the

segments

24 and 26, since they are of high permeability magnetic material, act as shunts or by-passes for the magnetic field represented by the lines 28, thus reducing the amount of the generated field which is available for actual deflection purposes. It will be appreciated that the degree of by-passing of the horizontal deflection field can be controlled by varying the size of the

segments

24 and 26 which are elfectively interposed in the field.

As disclosed in FIGS. 1-5, variation in the degree of magnetic field by-passing, and consequently the control of deflection width, is achieved by making the

segments

24 and 26 adjustably axially positionable. T 0 this end the

segments

24 and 26 are secured to, and project axially out from, an insulating sleeve 36, the

segments

24 and 26 being occasionally flared outwardly and having a degree of inherent deformability so as to tend to conform to the flared inner contours of the

windings

4A and 4B. The tube 3t) is axially slidable inside the support 2 and the

windings

4A and 4B and is adapted to be received directly over the neck of the cathode ray tube on which the assembly is mounted. As the tube 34 is slid in and out relative to the deflection yoke assembly, the segments 24 and 2d slide with it, and hence more or less of those segments are operatively interposed into, and act as magnetic shunts with respect to, the horizontal deflection field represented by the lines 23. In this way the etfect of that field on the electron beam is modified, thus C011: trolling th width of the display.

It is to be emphasized that since the segments 24 and 2d are substantially completely received in circumferential registration with the butt sections of the

windings

4A and 4B, and do not extend circumferentially into the windows-22 formed by those windings, and because the

segments

24 and 26 are magnetically permeable and not primarily electrically conductive, they will have no appreciable effect on the vertical deflection field generated by the vertical windings.

While FIG. 5 discloses an adjustable width

member having segments

2 and 26 each of a single piece (this corresponding also to the showing in FIG. 9), it has been found that effective width control is achieved, and at the same time specific control and minimization of pin cushion distortion is achieved, when each segment 24 and Z6 is defined by a similar plurality of separated

sections

24A, 24B and 26A and 2613 respectively. The

segments

24A and 24B and the

segments

26A and 26B are similarly designed and similarly symmetrically located. By thus subdividing the active area of the

segments

24 and 26 the shielding effect produced by those segments is so modified as to tend to correct the inherent pin cushion response of the deflection yoke, thus making it much easier to completely compensate for that effect through the use of auxiliary magnets, such as those designated 32, and in some instances making it possible to dispense with the use of such auxiliary magnets 32 altogether.

While the vertical deflection winding 6 has, in FIGS. 1-7, been disclosed as the saddle type, this is not essential, and FIG. 8 discloses a deflection yoke in which the vertical windings 6' are of the toroidal type, being wound about the magnetic core 8.

The embodiments of FIGS. 6-8 also diifer from that of FIGS. l-3 in that the

magnetic segments

24 and 26, specifically shown with each segment comprising a pair of

sec ions

24A, 24B and 26A, 26B respectively, are fixed in position rather than being adjustable. To this end the segment sections are adhesively secured to an insulating strip 34 (see FIG. 7) which is in turn adhesively secured to the radially inner surfaces of the butt section of the appropriate

horizontal Winding

4A or 4B. While, with this fixed and non-adjustable embodiment, compensation cannot be made from time to time for difterent operating conditions, nevertheless the fixed arrangement has been found to be very advantageous in reducing the sensitivity of the horizontal deflection electromagnetic circuit by a predetermined selectable amount, in that way bringing about the desirable result that the adjustment in width of the display image will not significantly add to the loading effects on the sweep circuit by normal variations in operating conditions, while at the same time, and particularly where each segment is formed in a plurality of separate sections, as shown, the pin cushion effect is controlled and minimized. For low cost production of commercial television receivers, this represents a substantial manufacturing advantage.

The particular shape of the

segments

24 and 26 may be varied as dictated by the geometry and electromagnetic characteristics of different installations in order to produce optimum effects, both in the fixed and adjustable embodiments here disclosed. Moreover, in the adjustable embodiment the shape of the segments can be modified so as to bring about a desired relationship between axial positioning of the segments and degree of width control achieved thereby. In those embodiments where the segments are divided into sections, it will be appreciated that the number of sections need not be limited to two, but instead three or more sections could be used for each segment. Fixed or adjustable compensation can be effected, as desired, with yoke assemblies of either of the types of FIGS. 1 and 8.

It is exceedingly significant that with the arrangement of the present invention, in which magnetically permeable segments are utilized to modify only a single dimension (here described in terms of the Width) of the display, and are therefore located substantially completely circumferentially within the butt sections of the horizontal windings, the increased loading eifect of prior art approaches to the problem of width control on the horizontal deflection circuitry is completely eliminated. The increased loading of the prior art approaches is generally indicated by an increase in the cathode current of the amplifier tube in the horizontal sweep circuit, and is also reflected in a reduced boost voltage when the fiyback cycle deflection system is used, that boost voltage controlling the final anode voltage of the display tube. It has been found that in connection with the present invention not only have these indications of increased loading not been present, but, on the contrary, in many instances an actual reduction in cathode current and an increase in boost voltage, and hence final anode power, has been noted. This gives rise to a marked increase in picture quality.

The structure and arrangement of the present invention, and its assembly with an otherwise conventional deflection yoke, is simple and inexpensive, and consequently excellently adapted to low price quantity production. Since it results in an actual improvement in the functioning of the deflection system, both in reducing loading, minimizing pin cushion effect, and increasing picture quality, in addition to performing its primary function of width control, it constitutes a very significant advance in the art.

While but a limited number of embodiments of the present invention have been here specifically disclosed, it

will be apparent that many variations may be made therein, all within the scope of the instant invention as defined in the following claims.

I claim:

1. In a cathode ray tube deflection assembly, a defiection winding comprising substantially axially extending conductor lengths connected by end turns, said axially extending lengths being formed into two coils, the butt sections defined by said axially extending winding lengths being separated by windows, and a pair of substantially diametrically opposed segments formed of high permeability magnetic material, each circumferentially and radially located substantially completely within a different one of said butt sections and extending along said butt sections substantially adjacent said windows.

2. The assembly of claim 1, in which the axial position of said segments relative to their respective butt sections is adjustable.

3. In the assembly of claim 2, a sleeve of insulating material axially slidably received radially inside said deflection winding, said segments being mounted on said sleeve.

4. In the assembly of claim 2, a sleeve of insulating material axially slidably received radially inside said defiection winding, said segments being mounted on said sleeve and extending axially forwardly therefrom.

5. The assembly of claim 1, in which said segments are fixedly mounted relative to their respective butt sections.

6. The assembly of claim 1, in which said segments are fixedly mounted on the radially inner surfaces of their respective butt sections.

7. In a cathode ray tube deflection assembly, a deflection winding comprising substantially axially extending conductor lengths connected by end turns, said axially extending lengths being formed into two coils, the butt sections defined by said axially extending winding lengths being separated by windows, and a pair of substantially diametrically opposed segments formed of high permeability magnetic material, each circumferentially and radially located substantially completely within a different one of said butt sections, each of said segments comprising a plurality of sections extending substantially adjacent said windows and separated from one another substantially centrally of said butt sections.

8. The assembly of claim 7, in which the axial position of said segments relative to their respective butt sections is adjustable.

9. In the assembly of claim 8, a sleeve of insulating material axially slidably received radially inside said defiection winding, said segments being mounted on said sleeve.

10. In the assembly of claim 8, a sleeve of insulating material axially slidably received radially inside said deflection winding, said segments being mounted on said sleeve and extending axially forwardly therefrom.

11. The assembly of claim 7, in which said segments are fixedly mounted relative to their respective butt sections.

12. The assembly of claim 7, in which said segments are fixedly mounted on the radially inner surfaces of their respective butt sections.

13. In a cathode ray tube deflection assembly, a deflection winding comprising substantially axially extending conductor lengths connected by end turns, said axially extending lengths being formed into two coils, the butt sections defined by said axially extending winding lengths being separated by windows, and a pair of substantially diametrically opposed segments formed of high permeability magnetic material, each located in a circumferentially substantially central position relative to a different one of said butt sections and radially and circumterentially sub stantially completely within its corresponding butt section, each of said segments comprising a plurality of sections extending substantially adjacent said Windows and separated from one another substantially centrally of said butt sections. I

14. The assembly of claim 13, in which the axial posi tion of said segments relative to their respective butt sections is adjustable.

15. In the assembly of claim 14, a sleeve of insulating,

material axially slidably received radially inside said de flection winding, said segments being mounted on said sleeve.

16. The assembly of claim 13, in which said segments are fixedly mounted on the radially inner surfaces of their respective butt sections.

References Cited by the Examiner UNITED STATES PATENTS 2,562,395 7/51 Schlesinger 317-200 X FOREIGN PATENTS 777,722 6/57 Great Britain.

JOHN F. BURNS, Primary Examiner.

JOHN P. WILDMAN, Examiner.

Claims

1. IN A CATHODE RAY TUBE DEFLECTION ASSEMBLY, A DEFLECTION WINDING COMPRISING SUBSTANTIALLY AXIALLY EXTENDING CONDUCTOR LENGTHS CONNECTED BY END TURNS, SAID AXIALLY EXTENDING LENGTHS BEING FORMED INTO TWO COILS, THE BUTT SECTIONS DEFINED BY SAID AXIALLY EXTENDING WINDING LENGTHS BEING SEPARATED BY WINDOWS, AND A PAIR OF SUBSTANTIALLY DIAMETRICALLY OPPOSED SEGMENTS FORMED OF HIGH PERMEABILITY MAGNETIC MATERIAL, EACH CIRCUMFERENTIALLY AND RADIALLY LOCATED SUBSTANTIALLY COMPLETELY WITHIN A DIFFERENT ONE OF SAID BUTT SECTIONS AND EXTENDING ALONG SAID BUTT SECTIONS SUBSTANTIALLY ADJACENT SAID WINDOWS.