FR2481843A1 - Extended parabolic profile deflection ring for CRT - has saddle shaped windings defined by two plastics formers for easy production self-convergent in line tube deflection - Google Patents

Abstract

The windings are wound inside the ferrite core, which consists of a cylindrical rear part and a parabolically flared front part. A plastics former is glued inside the rear part. The former consists of a series of internal slots to guide the wires parallel to the axis and a series of radial slots on the rear face. A second thin plastics former is placed against the front face of the deflection ring. The second former has a series of notches on its inside edge and dowels on the front face to provide the correct angular positioning of the wires. The deflection ring consists of at least two distinguishable toric sections forming the front and rear parts respectively.

Description

The present invention relates to a deflector, in particular for cathode ray tubes of the type comprising a toroidal deflection ring of elongated shape with a substantially cylindrical rear part and a front part which widens in a substantially parabolic profile.

 A more particular subject of the invention is improvements to the winding of these deflectors so as to enable better characteristics, notably of convergence and geometry of the electron beam subjected to the action of such a deflector, to be obtained.

Deviators with a deflection ring are well known, in particular for the horizontal and / or vertical scanning of a cathode ray tube (s). A conventional deflector consists of a deflection ring, made of ferrite, in the form of a divergent tubular portion, that is to say the outer contour of which is flared in an axial direction, and a winding of which the turns have their active part. , inside the ring, approximately located in planes passing through the main axis of symmetry of the deflection ring This winding mode is advantageous for its simplicity and ease of execution
On the other hand, the distribution of the turns around the nucleus determines the magneto-optical characteristics of the deflector.

With elongated magnetic cores comprising a substantially cylindrical rear part and a front part which widens in a substantially parabolic profile, it is theoretically possible to obtain the self-convergence of a color television tube with three cannons in line and good correction of the geometric distortion of the image, if a "saddle" winding is produced in which the internal turns of the deflector are not contained in the same plane for the cylindrical part of the ring and for the parabolic part.

Unfortunately, in practice, it is extremely difficult to produce such self-converging and distortion corrected windings, at least industrially.

 The object of the invention is to solve these difficulties.

To this end, a deflector according to the invention is characterized in that it comprises concentrically and internally at its rear part an attached ring, for example of plastic material, comprising on its internal face grooves or the like ensuring the guidance of the wires winding over substantially the entire length of said rear portion. In this way, it is possible, by arranging the turns of the winding in the rear part of the deflector in these grooves, to obtain directions different from the planes of the turns wound inside the deflector for the front part and for the rear part.

According to another characteristic of the invention, the deflector further comprises on its front face a second attached ring, for example of plastic material, of small thickness, comprising on its internal face small notches or teeth, ensuring the angular positioning of the wires winding at the front of the diverter. Thus, it is possible to guide and maintain the turns of the winding inside the front part of the deflector between the place where they leave the grooves of the internal ring provided in the rear part of the deflector and the place where they penetrate into the notches formed on the second ring at the front of the deviator.

In this way, it is possible without difficulty, using the rings mentioned, to simulate a ten saddle winding having all the required qualities of self-convergence and correction in geometry.
On the other hand, by providing on each of said rings projecting from the rear and front faces respectively of the deflector of the notches and / or pins, it is possible to wedge and guide the return of the winding wires on the corresponding sections of the deflector facilitating its production.

The invention will appear more clearly with the aid of the description which follows, given with reference to the accompanying drawings in which
FIG. 1 shows in perspective view a rear ring used according to the invention,
FIG. 2 shows, in the same way as FIG. 1, a front ring,
FIG. 3 shows in perspective and schematically how the winding turns are produced in such a type of deflector,
FIG. 4 schematically shows how winding is carried out in a deflector designed according to the invention and illustrating the modification-distribution of the winding between the front zone and the rear zone.

 Referring first to Figure 4, we see a deflector identified as a whole 1 comprising a substantially cylindrical O-ring ferrite forming rear part (AR) 2 of the magnetic core of the deflector, and an O-ring 3 of substantially section parabolic forming front part (AV) of the magnetic core of the deflector; the two parts 2 and 3 are, for reasons of manufacturing convenience preferably manufactured in two separate parts and are joined by any suitable means, for example by gluing.

 On the rear part of the diverter and concentrically thereto, an added ring 4 is introduced, the configuration of which in fluted sleeve appears more clearly in FIG. 1. The ring 4 comprises a circular cylindrical part 5 of small thickness which involves substantially the entire rear part of the magnetic ring 2. The internal face of the cylindrical sleeve portion 5 has grooves 6 formed between teeth 7 which, in the example illustrated, are directed along planes passing substantially through the axis y of the deflector.

 The ring 4 also includes a collar 8 which covers the rear face of the magnetic ring 2 on which it can be bonded.

 Teeth or projections 9 are provided on the flange 8 forming substantially radial notches between them 10.

 At the front end of the deflector, a second attached ring 11 is provided, more particularly visible in FIG. 2. The ring 11 is advantageously made, like the ring 4 of plastic material, and is fixed, for example by gluing to the end of the front face of the magnetic ring 3.

 The ring 11 is thin and has on its internal face small notches 12 formed between teeth 13 slightly projecting from the internal face of the magnetic ring 3.

 On the other hand, the ring 11 has projecting pins 14 on its front end face.

On the internal face of the deflector are formed the active turns 15, 16.

The general shape taken by each turn such as 15, 16 appears more clearly in FIG. 3, the wire returning at each end to the edges 17, 18 of the deflector (without therefore passing through from the outside).

 As can be seen more clearly in FIG. 4, due to the grooves 6 formed in the ring 4, projecting from the internal surface of the deflector, and due to the notches 12 provided on the front ring 11 projecting from the internal face of the deflector , it is possible to wind the turns 15, 16 by giving them a different distribution between the front zone and the rear zone of the deflector. On the other hand, the notches 10 of the ring 4 and the pins 14 of the ring 11 allow the setting and return without difficulty of the winding wire on the corresponding edge of the deflector.

 In the example illustrated in FIG. 4, it can be seen that the turns 15, 16 are wound in the rear part 2 substantially along planes passing through the axis z of the deflector (guided as they are by the notches 6), while that in the front part, they are no longer coils in such planes but inclined according to a profile calculated so as to give the best characteristics of self-convergence and correction of desired images. In this part, the wires are suitably held taut between the outlet of the grooves 6 and the small notches 12 of the front ring 11.

 Such deflectors are advantageously used in particular in color television tubes with three cannons arranged in line ".

Of course, the invention is in no way limited to the illustrated and described embodiment which has been given only by way of example, the invention comprising all the technical equivalents of the means described as well as their combinations if these are carried out according to its spirit and implemented within the framework of the claims which follow.

Claims (2)

1. Diverter in particular for cathode ray tubes of the type comprising a toroidal deflection ring of elongated shape with a substantially cylindrical rear part and a front part flaring in a substantially parabolic profile, said ring forming a magnetic core comprising at least one winding wound at least on its internal face, said deflector being characterized in that it com-. door, concentrically and internally at its rear part (2), an attached ring (4), for example of plastic material, having on its internal face grooves or the like (6, 7) ensuring the guidance of the winding wires over substantially all the length of said rear part  24 Diverter according to claim. 1, characterized in that said ring (4) further comprises notches (10) substantially radial projecting from the rear end face of the deflector, allowing the setting and return of the winding wires on the corresponding edge of the deflectors 3. Diverter according to claim I or claim 2, characterized in that it comprises on its front face a second added ring. (11), for example of plastic material, of small thickness, comprising on its internal face small notches or teeth (12, 13) ensuring the angular positioning of the winding wires at the level of the front face of the deflector  4 diverter according to claim 3, characterized in that said second ring (îî) further comprises, projecting from the front end face of the diverter, pins or the like (14) allowing the setting and return of the winding wires on the corresponding edge of the diverter. 5. Diverter according to any one of claims 1 to 4, characterized in that said ring is constituted by at least two distinct O-ring parts forming one substantially said rear part (2), llautre substantially said front part (3).