JPS5947953B2 - flyback transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention aims to provide a flyback transformer that can efficiently extract a larger focus voltage.

Current flyback transformers are mainly of the direct rectification type, which are impregnated and molded with thermosetting resin such as epoxy.

For wiring, a high-voltage winding is often divided into multiple parts and a diode is inserted between them. This reduces the AC pulse voltage by dividing the high-voltage winding, and
This is because a higher voltage is generated due to the accumulation of AC pulse voltages, so compared to the case where the high voltage winding is not divided, the AC component is smaller, insulation becomes easier, and the device can be made smaller and lighter. Furthermore, since the high-voltage winding is divided, the equivalent secondary side capacity is reduced and high-order tuning becomes possible. The present invention uses the above-described flyback transformer to efficiently extract a larger focus voltage, and the present invention will be described below with reference to the drawings. In FIG. 1, numerals 1, 2, 3, and 4 are divided high-voltage windings, and between each winding, there are rectifier diodes 6,
T, 8, and 9 are connected.

5 is the primary winding, and the beginning of winding is +B power supply (not shown)
, the end of the winding is connected to the collector or emitter (not shown) of a horizontal output transistor.

Anode 1 of cathode ray tube 13 from cathode of diode 6
4 is supplied with high pressure. A medium-high voltage is taken out from the electric (alternating current) center point of the winding 2 (focus winding), lowered to an appropriate voltage by dividing resistors 10, 11, and 12, and the focus voltage is supplied to the focus electrode 15 of the cathode ray tube 13. are doing. 4 is a high voltage side winding, and 1 is a low voltage side winding.

FIG. 2 schematically shows the pulse voltage generated in the high-voltage winding in the wiring diagram of FIG. 1.

Explain why such a pulse voltage is generated. Considering one of the multi-divided high-voltage windings shown in FIG. 1, as shown in FIG. 3, a diode B.
C is connected in the direction of current flow. In this connection diagram, as shown in FIG. 4, the line capacitance and ground capacitance of the secondary winding can be equivalently written as C1, C2, and lumped constant capacitance. This can also be rewritten as shown in FIG. As can be seen from Figure 5,
The pulse voltage generated in the secondary winding A is C1 and C in FIG.
Considering the ground potential, a positive pulse voltage is generated at C1 and a negative pulse voltage is generated at C2. At the electrical midpoint of the winding, no pulse voltage is generated, but a DC voltage is generated. For the above reasons), in the wiring diagram shown in FIG. 1, high voltage is generated by the alternating accumulation of positive and negative pulse voltages, as shown in FIG. In FIG. 2, A shows the result by the coil 1, the opening shows the result by the coil 2, C shows the result by the coil 3, and 2 shows the result by the coil 4. The focus voltage is supplied to the electrical intermediate points of the winding 2 where no pulse voltage is generated. This focus voltage supply means is an extremely effective means because a DC voltage can be obtained without using a rectifying element such as a diode. In the flyback transformer of the above-mentioned means, the present invention is configured as follows in order to more efficiently generate a focus voltage.

In Fig. 5, if the values of C1 and C2 are equal, the magnitudes of the positive and negative pulse voltages are equal, and the electrical midpoint where no pulse voltage is generated is at υ of the 5 total turns of the secondary winding A. It is in.

If the values of C1 and C2 are different, for example, if C1>C2, the voltage divided by the capacitance of C2 will be larger than C1.
The negative pulse voltage (as well as the positive pulse voltage) also increases. Then, the electrical midpoint is formed in the direction of the third winding end of all the windings of the secondary winding. As mentioned above, C1 and C are the equivalent summation of the ground capacitance and line capacitance of the secondary winding, so for example, for winding 2 in Fig. 1, C
1. C2 is the capacitance of diodes 8 and 9, and winding 4
The inter-winding capacitance between winding 3 and winding 2, the inter-winding capacitance between winding 1 and winding 2, the winding method of winding 2, the number of turns of winding 2, the wire diameter of winding 2,
Depends on etc.

If the secondary winding shown in Fig. 1 has a structure in which the appropriate number of turns is wound for each slit on a bobbin having a plurality of ribs, and is impregnated and molded with thermosetting resin such as epoxy, then As shown in the figure, when winding 2 and winding 3 are brought close together and winding 1 and winding 2 are separated, the inter-winding capacitance between winding 2 and winding 3 is The capacitance between the windings is larger than the capacitance between the windings.

That is, C1 in the triangle in FIG. 5 increases and C2 decreases. Therefore, the negative pulse voltage is larger than the positive pulse voltage.
The electrical midpoint moves from the center of the winding toward the end of the winding.
The voltage at the electrical midpoint when looking at the ground potential is clearly C.
The value is larger in the case of 1>C2, and when this is used as a focus voltage, the focus voltage can be generated more efficiently in the case of C1>C2 than in the case of C1=C2. This is shown in Figure 6A. Shown in b. In Fig. 7, the same parts as in Fig. 1 are indicated by the same numbers, 16 is a thermosetting resin, 17 is a high-voltage winding bobbin, 18 is a case, 19 is a primary winding bobbin, and 20 is a terminal for connecting to an external circuit. It's a pin. As described above, by changing the distance between the windings, the focus voltage can be increased using the same winding without using any additional electrical components.

In other words, it is possible to generate a given focus voltage with fewer secondary windings.
This is an extremely effective means for high-order tuning, low ringing voltage flyback transformers. In particular, in the case of high-bipotential cathode ray tubes that have been used in recent years, the focus voltage supplied to the flyback transformer is 30% of the anode voltage.
~32% is required. Therefore, the focus voltage supply windings (in the case of Figure 1, windings 1 and 2) have a much larger number of windings than the other windings, resulting in high-order tuning. , it was extremely difficult to design a low ringing voltage flyback transformer. The present invention can be said to be an extremely effective method for improving this. Although the distance between the winding 3 and the winding 4 is not mentioned, in order to balance the divided voltage of the diode, it is better to keep the distance between the winding 2 and the winding 3 as close as possible. But either is fine. Furthermore, even when the number of divisions of the high-voltage winding is three (the diode between winding 3 and winding 4 is eliminated, and the winding is reduced to one winding), the contents described above can be applied. Further, as shown in FIG. 8, a thermosetting resin 16 is provided between the winding 2 and the winding 3, and a thermosetting resin 2 having a dielectric constant larger than that of the bobbin IT is provided.
0, the inter-winding capacitance between windings 2 and 3 will be larger than the inter-winding capacitance between windings 1 and 2, and the focus voltage can be made larger. .

As described above, according to the present invention, a higher focus voltage can be obtained using the same number of windings.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of a flyback transformer according to an embodiment of the present invention, Fig. 2 is a pulse waveform diagram for explaining the flyback transformer, Fig. 3, Fig. 4, and Fig. 5 are the same flyback transformer. A circuit diagram for explanation, FIG. 6A and b are waveform diagrams for explanation of the same flyback transformer, FIG. 7 is a cross-sectional front view of the same flyback transformer, and FIG. 8 is a flyback of another embodiment of the same. FIG. 3 is a sectional front view of the transformer. 5...Primary winding, 1, 2, 3, 4...
Secondary winding, 6, T, 8, 9...Diode, 1
0, 11, 12... Divided resistance, 13...
・Cathode ray tube, 20...Thermosetting resin.

Claims (1)

[Claims] 1. The secondary winding is divided into at least three parts, and diodes are installed between each winding and at the high voltage terminal of the high voltage side winding among the three windings. The windings are connected so that current flows from the low voltage side winding to the high voltage side winding, and the distance between the windings between the low voltage side winding and the focusing winding connected to this winding via a diode is The distance between the winding connected to the high voltage side terminal of the focus winding via a diode and the focus winding is set to be greater than the distance between the windings, and the focus voltage is extracted from the AC midpoint of the focus winding. Features a flyback transformer. 2. A resin inserted between the focus winding and the winding connected to the high voltage side terminal of the focus winding via a diode, and between the low voltage side winding and the focus winding, and each of the above windings. 2. The flyback transformer according to claim 1, wherein a resin having a dielectric constant higher than that of the bobbin around which the bobbin is wound is inserted.