MXPA96005911A - High voltage transformer for detelevis receiver - Google Patents

Abstract

The present invention relates to a high voltage transformer for a television receiver comprising: a coil former in which auxiliary windings are arranged, a primary winding disposed on the auxiliary windings and a high voltage winding disposed on the primary winding; a first sleeve forming a flat base for the primary winding, being placed between the auxiliary windings and the primary winding, wherein the primary winding is wound from a plurality of solid wire layers which are directly placed on top of each other; second sleeve made of a dielectric material is inserted between two of the primary layers to reduce the winding capacitance of the primary winding, and a second coil former disposed about the first coil former with the primary winding, with the second coil former being disposed around the high volta winding

Description

HIGH VOLTAGE TRANSFORMER FOR TELEVISION RECEIVER.

D E S C R I P C I O N The invention is based on a high-voltage transformer for a television receiver according to the preamble of clause 1. In the case of a transformer of this type, it is known to wind the primary winding with a multiple-stranded wire. The use of braided multiple wire. The use of multiple braided wire for the primary winding is necessary in order to keep the so-called surface losses sufficiently low, in particular at relatively high line frequencies of 32 kHz. However, a primary winding made of braided multiple wire is more expensive than a solid wire by a factor of about 7 and has disadvantages during the winding operation, during welding and the socket is being fastened to the transformer connection terminals.

The invention is based on the object of designing such a high-voltage transformer such that solid wire can be used instead of multiple braided wire for the primary winding and, irrespective of this, the requirements with respect to coupling are satisfied. , copper losses and surface losses. This object is achieved by means of the invention specified in clause 1. Advantageous developments of the invention are specified in the sub-clauses.

According to the invention, then, the primary winding is wound up from pluralities of solid wire layers lying on top of one another and a sleeve made of a dielectric material between each two layers is inserted.

To date, it has been assumed that the use of braided multiple wire is essential for the primary winding of the high voltage transformer due to surface losses that occur otherwise, in particular at a high line frequency of 32 kHz. The solution according to the invention is based on the following ideas and considerations: The winding capacitance of the primary winding is considerably reduced by the insertion of the sleeve between the two layers of the primary winding which are one on top of the other. Consequently, the capacitive reactive currents also become correspondingly smaller. Since reactive currents are the main cause of surface losses, the reduction in the capacitance of the winding causes the surface losses occurring in the primary winding to become correspondingly lower. The reduction in surface losses therefore makes it possible, surprisingly, to use a solid wire instead of a braided multiple wire for the primary winding even at relatively high frequencies of 32 kHz. The relatively inexpensive sleeve between the two layers of the primary winding, therefore renders unnecessary the expensive braided multiple wire previously necessary for the primary winding. It can be inherently assumed that the coupling of the transformer is reduced by the insertion of the sleeve. However, it has been shown that this is not the case. This is due to the fact that the radial distance on the extended primary winding is practically increased in comparison with the known transformers, as a result of the individual layers, in other words the somewhat extended flattened primary winding. As a result, a good coupling between the primary winding and the high voltage winding is still ensured.

Above all, the invention produces the following advantages. The costs of the transformer become significantly low, because the primary winding has the relatively expensive braided multiple wire replaced by the solid wire, which is cheaper by a factor of 7. In spite of this, a good coupling of the transformer is achieved because the solution according to the present invention, allows a structure that is narrower in the radial direction. Low copper losses and low surface losses also lead to a reduction in transformer heating. The solid wire instead of the additionally braided multiple wire has the advantage that it can be welded better and faster during production. The winding operation and the ability to wind the ends of the wire over the transformer connection terminals are also significantly improved.

The primary winding preferably consists of two layers with a copper wire insulated by two layers of enamel, and a so-called CuEE wire, is inserted whereby the sleeve has a wall thickness of the order of magnitude of 0.4 to 0.8 mm. The individual layers of the primary winding are in this case preferably designed as a bifilar winding with two wires lying one after the other. In other words, the two wires are continuously wound in parallel at the same time.

It is also possible to wind a first layer of the primary winding directly on the auxiliary windings without the interposition of a sleeve. This is particularly advantageous when the first layer only has a small number of turns.

Preferably, the sleeve is produced as a cylindrical plastic injection molding having a wall thickness of 0.4 to 0.8 mm. The sleeve is grooved in the longitudinal direction and can be placed on the coil former so that it expands in the radial direction. The sleeve may also consist of a plurality of layers of film or paper.

In the preferred embodiment of the invention, the length L of the coil former in the axial direction is significantly smaller than the external diameter D of the complete coil former for auxiliary windings, ie the ratio of L / D is appreciably less than 1.

Such a structure allows reducing costs and weight, in particular for the ferrite core.

The invention is explained in the following with reference to the drawings, in which: Figure 1 shows the structure of a high voltage transformer made in accordance with the present invention.

Figure 2 shows values of the inductance and non-reactive resistance of the primary winding of this transformer as a function of frequency; Y Figure 3 shows the circuit of a line output stage with high voltage generation using a transformer according to figure 1.

Figure 1 shows limb 1 of the high voltage transformer core. Preferably the core is designed as a U / U core, as an E / I core or as a U / I core. The coil former 2 is disposed on the limb 1 of the core. Located at the bottom of the coil former 2 is, first of all, a plurality of auxiliary windings 3, for example to generate operating voltages, pulse voltages and to heat the picture tube. The auxiliary windings 3 have a non-uniform surface. For this reason, the sleeves 4 made of a dielectric material and having a wall thickness of, for example, 0.4 to 0.8 mm are arranged on the auxiliary windings 3 and form a smooth base for the primary winding. The first primary winding element Pl is first arranged in the form of a layer on the sleeve 4. The winding element Pl is wound in a bifilar manner with a CuEE wire having a diameter of 2 x 0.45 mm. An additional sleeve 5 is on the winding element Pl. The second primary winding element P2, which is connected in series with the winding element Pl, is on the sleeve 5. The sleeve 5 performs, in the manner described, the reduction in winding capacitance of the complete windings Pl, P2 and as a result, the advantages that have been previously mentioned. The coil former 2 is surrounded by the camera-type coil former 6, in whose chambers 7 the winding 8 is located.

Figure 2 shows the advantages achieved by the transformer according to figure 1. Columns a and b show the inductance L and the non-reactive resistance R of the primary winding P as a function of the frequency f for a known transformer. It is evident that the values of L and R increase considerably when the frequency f increases. The frequencies f shown are present in practice as a result of the harmonics in the current of the primary winding Pl which occur in particular in a transformer at a high line frequency of 32 kHz. The pronounced increase in L and R when the frequency f increases leads to the production of considerable surface and copper losses in the transformer.

The columns c and d in Fig. 2 show the values of L and R for a transformer according to Fig. 1. It is evident that the values of L and R are increased, desirably, significantly less with the frequency f than in the case of known transformers, as revealed in columns a and b. Consequently, the surface and copper losses in the transformer are considerably reduced because of these reduced values of L and R, in particular at relatively high frequencies, with the result that it is now possible, in the manner described, to use a wire Solid significantly more economical for the primary P winding instead of the braided multiple wire.

Figure 3 shows a line deflection circuit with the high voltage obtained using a transformer having the structure according to figure 1. This figure shows the switching transistor 13, which is controlled by the frequency switching voltage 12 of line, the return diode 14, the return capacitor 15, the coupling or capacitor 16 tangent, the line deflection coils 17, the primary winding connected to an operating voltage UB and having the primary winding elements Pl and P2 connected in series according to Figure 1, an auxiliary winding 3, which generates an operating voltage Ul via the rectifier circuit 10 and the high voltage winding 8, which generates the high voltage UH for the image tube 18 via the rectifier High voltage D According to FIG. 1, the sleeve 5 is arranged between the primary winding elements Pl and P2.

Claims (7)

R E I V I N D I C A C I O N S

1. - High voltage transformer for a television receiver having a coil former in which auxiliary windings are located, the primary winding on the latter and the high voltage winding on the primary winding, a sleeve forming a flat base for the The primary winding is arranged on the auxiliary windings; characterized in that the primary winding is wound on a plurality of solid wire layers that are on top of each other and a sleeve made of a dielectric material is inserted between two layers.

2. - Transformer according to clause 1, characterized in that the primary winding consists of two layers and a copper wire isolated by two layers of enamel.

3. - Transformer according to clause 1 or 2, characterized in that the layers of the primary winding are formed by bifilar windings.

4. - Transformer according to clause 1, characterized in that a first layer of the primary winding is directly on the auxiliary windings without the interposition of a sleeve.

5. - Transformer according to clause 1, characterized in that the sleeve is produced as a plastic injection molding.

6. - Transformer according to clause 1, characterized in that the sleeve consists of a plurality of layers of film or paper.

7. - Transformer according to clause 1, characterized in that the length of the coil former in the axial direction of the core is appreciably smaller than the outer diameter of the coil former. SUMMARY In the case of a high voltage transformer for a television receiver, it is known to arrange on a coil former a plurality of auxiliary windings first, on the latter a sleeve to form a flat base for the primary winding that is on them and on the primary winding the high-voltage winding in the form of a camera-type winding. The primary winding is wound with multiple braided wire instead of solid copper wire, in particular at a high line frequency of 32 kHz, for example HDTV, in order to reduce the surface and copper losses that increase with the high frequency. However, that winding made of braided multiple wire is more expensive than a winding made of solid wire by a factor of about 7. The object is to develop a transformer of this type in such a way that the solid wire can be used in place of a braided multiple wire and independently of this the coupling and loss requirements are met. According to the present invention, the primary winding P is wound from a plurality of layers (Pl, P2) of solid wire that are on top of each other and a sleeve (5) of a dielectric material is located between each two layers . In particular, it is a high voltage transformer for a television receiver at a high line frequency of 32 kHz. Fig. 1