EP0286484A1 - Winding method for non-radial windings of a CRT deflector - Google Patents

Abstract

To avoid the use of adhesives or notched parts when winding non-radial layers of a cathode-ray tube deflector, a large-pitched radial layer (24) is first wound, which acts as notches for the layers following non-radial winding (25).

Description

The invention relates to a winding method for non-radial winding of a cathode ray tube deflector.

Trichrome cathode ray tubes in line with barrels are currently equipped with deflectors themselves realizing the auto-convergence of the electron beams and the corrections of image geometry. The line field, created by saddle-shaped coils, is said to be "positive astigmatism", while the field field is said to be "negative mean astigmastime" to ensure convergence and to "positive forward astigmatism" to ensure geometry correction.

In the field of consumer television, various methods are used to produce a frame winding in accordance with the above requirements: either a saddle-shaped coil or a toroidal coil can be used. The toroidal coil can be produced either with a radial frame cooperating with field conformers (ferromagnetic parts attached to the deflector), or by using an inclined winding technique with a rear angle greater than the front angle, such winding being able to also be associated with magnetic correction means. The latter solution, widely used, generally uses one of the following three techniques for winding:
- Plastic parts are used provided with notches fixed at the front and at the rear of the ferrite, these notches determining the inclination of the winding wire. This process makes it possible to obtain strong inclinations of the wire, but is expensive because it requires the use of special parts and additional handling of these parts, which increases the manufacturing time.
- The wire is spooled onto the bare ferrite, possibly notched, but the inclination of the wire is then very limited (approximately 15 ° at most) because the wire tends to slip generally asymmetrically.
- Or finally, we use, to avoid slippage of the wire, adhesive elements deposited on the ferrite at the front and rear planes, these elements can be adhesive tapes, glues, waxes, etc. Such a process is expensive, difficult to automate, and does not allow wire inclinations greater than about 20 °.

The subject of the present invention is a winding method making it possible to obtain winding wire inclinations of up to approximately 30 ° on the edges of the winding, on bare ferrites without notches, without the addition of parts or of adhesive element. , a process that can be easily automated.

The method according to the invention consists in producing a first winding layer at least approximately radially with a large winding pitch, then in depositing the following non-radial layers using at least part of the wires of the first layer to avoid the sliding of the following layers.

• - les figures 1 à 4 sont différentes vues d'un bobinage de trame de l'art antérieur utilisant des encoches en matière plastique,
• - les figures 5 et 6 sont des vues de face et de côté d'un bobinage de trame de l'art antérieur utilisant des adhésifs de retenue du fil,
• - la figure 7 est une vue partielle de dessus d'une machine de bobinage classique au cours de la réalisation de la première couche du bobinage conforme à l'invention,
• - la figure 8 est une vue de côté d'une demi-ferrite bobinée conformément à l'invention, pendant le bobinage des couches non radiales,
• - les figures 9 et 10 sont des vues de derrière et de côté d'un bobinage de trame à plusieurs couches, conforme à l'invention.

The invention will be better understood on reading the description of an embodiment taken as a nonlimiting example and illustrated by the appended drawing in which:

• FIGS. 1 to 4 are different views of a weft winding of the prior art using plastic notches,
• FIGS. 5 and 6 are front and side views of a weft winding of the prior art using yarn retaining adhesives,
• FIG. 7 is a partial top view of a conventional winding machine during the production of the first layer of the winding according to the invention,
• - Figure 8 is a side view of a half-ferrite wound in accordance with the invention, during the winding of the non-radial layers,
• - Figures 9 and 10 are rear and side views of a weft winding with several layers, according to the invention.

FIGS. 1 and 2 show exploded front and rear views of the two half-ferrites 1,2 each comprising a half-frame winding 3,4. The wires of the half-windings 3,4 are not arranged radially, that is to say that they are not parallel to the generatrices of the conical surface formed by the half-ferrites 1,2. These wires form with respect to these generators a variable angle of inclination according to the position of the strands of wire within the winding and as a function of the angular position of the notches. To keep all the turns of the two half-coils in place, plastic parts with notches 5,6 and 7,8 are fixed on the front and rear end faces of each half-ferrite 1,2. The successive turns of the half-windings 3,4 are maintained by these notches, which allows them to be wound with a high angle of inclination.

FIGS. 3,4 show two side views, considered at 180 ° relative to each other, of a finished deflector, produced from the elements of FIGS. 1 and 2.

FIGS. 5 and 6 show another embodiment of a deflector of the prior art. For this embodiment, there are deposited on the front and rear end faces of the two half-ferrites, or near these front faces on the periphery of these half-ferrites, eight segments of adhesive material 9 to 16, for example tape double-sided adhesive or adhesive paste. These segments are deposited at the ends, in the peripheral direction, of the half-windings 17, 18 of the deflector 19, projecting slightly outwards. Indeed, it is generally sufficient to immobilize the extreme turns of the first layer to prevent the turns of the layers following to slide.

The process of the invention will now be described with reference to FIGS. 7 to 10. The winding machine, partially shown in FIG. 7, essentially comprises a device 20 for holding and driving in rotation the half-ferrites 21, and a rotary wire guide 22 (better known under the English name of "flyer"), the axis of rotation 23 of which is perpendicular to the axis B of the half-ferrites 21 in the radial winding position.

FIG. 7 shows a half-ferrite 21 on which the wire guide 22 is depositing the layer of radial winding 24 at large pitch. The turns of this first layer being substantially radial (that is to say truly radial or inclined by a few degrees), have a stable positioning relative to the portion of conical crown formed by the half-ferrite whose generator is also radial . These turns will be difficult to move when removing the following non-radial layers (or at least for the second layer which guides the following) for which they act as retaining notches. Of course, the radial winding and the non-radial winding are carried out with the same wire, without interruption.

According to a first embodiment of the invention, the pitch (angle of rotation of the ferrite or of the "flyer" around the axis B for a turn) of this first layer 24 is constant and equal to approximately 2 to 5 times the pitch of a winding with contiguous turns made with the same wire.

According to a second embodiment of the invention, this pitch is variable: it has a first value P1 at the ends of the layer, and a second value P2, greater than P1, in the middle of the layer. Preferably P1 is equal to approximately 2 to 5 times said pitch of winding with contiguous turns, and P2 is equal to approximately 2 to 3 times P1. As can be seen in FIGS. 8 to 10, the layer 24 must be sufficiently wide, in particular at the rear of the ferrite and protrudes slightly at the front (from 5 turns approximately) of the following layers, in order to be sure that the extreme turns of the non-radial winding will always be maintained by those of the layer 24 without the need to position with great precision the first turn of the non-radial winding 25 , compared to layer 24.

To make non-radial windings according to the invention, the half-ferrite 21 is inclined around an axis contained in the break plane P (the plane of separation between two half-ferrites formed by breaking of an entire ferrite) . In Figure 8 we see the trace T of this axis (which is perpendicular to the plane of the drawing). Let B be the machine axis (axis around which the machine rotates the half-ferrites to make the radial windings). The angle I formed by B and P is the angle of inclination of the ferrite. The angles of inclination of the different turns of the non-radial winding 25 depend on the angle I and on the angular position of these turns within the winding.

The angular distribution of the different turns of the resulting winding (24 + 25) is the composition of the distribution of the different layers, the effect of the first one being weak insofar as its number of turns is low.

The average inclination of a half-ferrite carrying a non-radial winding produced in accordance with the invention is equivalent to that obtained with a ferrite inclined for all the turns, minus the fact that the first layer is not inclined. If the total winding (24 + 25) has N turns, and the first layer n turns, the equivalent inclination Ieq of the half-ferrite 21 will be:
I eq = I (N - n) / N
I being the angle of inclination of the half-ferrites (Figure 8).

For example, a winding of 440 turns in four layers in steps of 1 °, occupying a center angle of 110 °, on a ferrite inclined at an angle I = 20 °, and produced according to a method of the prior art, is equivalent to a winding produced, in accordance with the invention, by winding a first radial layer of 40 turns in 3.4 ° steps (therefore occupying an angle at the center of about 136 °) , on which four non-radial layers of 100 turns are each wound in 1.1 ° steps on an inclined ferrite of Iʹ = 22 °.

In addition, it is advantageous that the winding pitch of the non-radial layers is greater than that which would have been without the first radial layer, so as to allow the wires of this first layer to be interposed in the turns of the subsequent layers of the winding without disturbing the arrangement too much.

The process of the present invention can be implemented when it is desired to obtain a winding whose coverage angle (angle at the center formed by the two extreme turns of the winding, in a plane PA perpendicular to the axis of the ferrite ) front is greater than the rear coverage angle (that is to say for a plane PA passing through the front or rear front face, respectively of the ferrite), and this, with a first radial layer (like said layer 24). After having wound the first layer, the half-ferrite is tilted in a direction opposite to that shown in FIG. 8. This type of winding is useful in particular for producing a self-converging deflector giving an image having good resolution uniformity.

Claims (6)

1. Winding method for a non-radial winding of a cathode-ray tube deflector, characterized in that a first winding layer (24) is produced at least approximately radially, and that the following layers are deposited not radial (25) using at least part of the threads of the first layer to prevent slipping of the following layers. 2. Method according to claim 1, characterized in that the pitch of the winding of the first layer is constant. 3. Method according to claim 2, characterized in that the pitch of the winding of the first layer is equal to approximately 2 to 5 times the pitch of a winding with contiguous turns produced with the same wire. 4. Method according to claim 1, characterized in that the pitch of the winding of the first layer is variable and has a value, at the ends of the layer, less than that in the middle of the layer. 5. Method according to claim 4, characterized in that the pitch at the ends of the layer is equal to approximately 2 to 5 times the pitch of a winding with contiguous turns formed with the same wire, and that in the middle of the layer it has a value equal to about 2 to 3 times that at the ends. 6. Method according to any one of the preceding claims, characterized in that the winding pitch of the non-radial layers is greater than that which would have been without the first radial layer.

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