JPS6020883B2 - flyback transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flyback transformer used for supplying DC high voltage to a cathode ray tube of a TV receiver, etc.
More specifically, the present invention relates to a flyback transformer that has been improved to have a smaller ringing ratio.

In general, a flyback transformer consists of a primary winding that is an input winding, a secondary winding that is a high voltage output winding, and AFC, A
A tertiary winding for extracting signals such as GC and secondary B power is magnetically coupled to each other, and the primary winding and tertiary winding are particularly closely coupled. be. A flyback transformer configured in this manner is required to have a ringing ratio as small as possible in order to operate efficiently. This ringing ratio is the first peak value B of ringing, as shown in Figure 1, which represents a high voltage pulse when fifth-order tuning is induced on the secondary side of a flyback transformer.
, the peak value of the shot pulse, and the ringing peak value B
It is the ratio of A to the sum of A. In other words, the ringing ratio is R
r: Amount X・〇. It refers to the value expressed in (%).
And in the secondary flyback transformer, Part 2
The ringing ratio is reduced by appropriately tuning the resonance circuit between the leakage inductance and stray capacitance of the next winding. However, since the ringing and the shot pulse caused by this method change in relation to each other, it is very difficult to adjust the ringing, and even if the peak value of the ringing is reduced below a certain value, the peak value of the shot pulse must be simultaneously reduced. Therefore, there is naturally a limit to the improvement of the ringing ratio. The present invention has been made in view of these points, and an object of the present invention is to provide a flyback transformer in which the ringing ratio can be adjusted extremely easily by completely new means, and the value can be made smaller than before. This is the purpose.

The specific configuration is such that at least a part of the tertiary winding for purposes other than taking out the secondary B power source has a weak magnetic coupling with the primary winding, and the secondary winding is connected to the primary winding. The tertiary winding is wound at a position where it intersects with the leakage magnetic flux, and the tertiary winding is connected to a load through a rectifier circuit to be rectified during the scanning period. Accordingly, only the peak value of the ringing is reduced regardless of the shot pulse. An embodiment of the present invention will be described in detail below with reference to the drawings.
In Fig. 2, 11 is a low-voltage coil bobbin that has a plurality of winding grooves formed on the core 12, 13 is a primary winding that is dividedly wound into each winding groove of this low-voltage coil bobbin 11, and 14 is this divided winding. 3 each wound on the primary winding 13
This is the secondary winding, which is used for purposes other than extracting the secondary B power supply for extracting signals such as AFC, AGC, etc., and has a loose magnetic coupling with the primary winding 13, and will be described later. It is wound on the primary winding 13 with a thick insulating material 15 such as a resin film interposed therebetween in order to bring it close to the secondary winding.

Note that the winding direction of the tertiary winding 14 is arbitrary;
This tertiary winding 14 is connected to a so-called scanning period in which rectification is performed only during the scanning period of a horizontal deflection circuit of a TV receiver or the like when a load is connected through a rectifying circuit consisting of a rectifying element such as a diode and a smoothing capacitor. It is used in such a way that rectification is achieved. The circuit that performs this scanning period rectification can take several configurations depending on the combination of the winding direction of the tertiary winding 14 and the connection direction of the rectifier elements of the rectifier circuit connected thereto. In short, it is sufficient to configure the circuit so that the rectifier elements such as diodes that make up the rectifier circuit connected to the tertiary winding are not conductive during the retrace period of the horizontal deflection circuit and are only conductive during the scanning period. . Reference numeral 16 designates a high voltage coil bobbin having a plurality of winding grooves mounted on the low voltage coil bobbin 11; 17 represents a secondary winding that is dividedly wound in each winding groove of the high voltage coil bobbin 16; It covers the secondary winding 14 and is formed close to the tertiary winding 14.

The flyback transformer of the present invention is basically configured as described above.

In other words, in a conventional flyback transformer, all of its tertiary windings are formed to be tightly magnetically coupled to the primary winding, and the tertiary windings used for purposes other than extracting the secondary B power are rectified. Although it was not intended to be used by connecting a circuit, ``In the present invention, the magnetic coupling of the tertiary winding with the primary winding is weak, and the leakage magnetic flux of the secondary winding with respect to the primary winding is reduced. The major feature is that the load is connected to the point formed at the position interlinked with the tertiary winding and the tertiary winding through a rectifier circuit, and that the rectification method uses scanning period rectification.Next Next, the functions and effects of the flyback transformer configured as described above will be explained.

Now, as shown in the circuit diagram of FIG. 3, the flyback transformer of the present invention has a horizontal deflection circuit 18 on the primary winding 13 side, a rectifier circuit 19 on the secondary winding 17 side, and a diode on the tertiary winding 14 side. Rectifier circuit 2 consisting of a rectifying element such as and a smoothing capacitor
Connect 0 to each.

Here, the tertiary winding 14 is connected so that its rectification method is scanning period rectification, as described above. A rectangular wave pulse signal of 15.7 degrees is applied to the input side of the primary side horizontal output transistor configured in this way, and a resistor 21 is connected to the tertiary winding 14 via the rectifier circuit 20. Then, the pulse waveform induced in the secondary winding 17 when fifth-order tuning was performed was observed using a synchroscope.
As a result, a waveform as shown in FIG. 4a was obtained, and the value of the ringing ratio determined from this waveform was 11.0%. In order to compare the flyback transformer of the present invention with a conventional one in which all of the tertiary windings are tightly magnetically coupled to the primary winding, the tertiary winding 14 in FIG. is wound directly on the primary winding 13 with the insulating material 15 removed, and the other structure is exactly the same as that of the embodiment shown in FIG. The resulting pulse waveform was observed in the same manner as described above.
As a result, a waveform as shown in FIG. 4b was obtained, and the value of the ringing ratio determined from this waveform was 16.5%. From this fact, the flyback transformer of the present invention
It can be seen that the ringing ratio is greatly improved compared to the conventional one. The reason why the ringing ratio has been greatly improved is that, as is clear from comparing the waveforms in Figure 4 a and b, the shot pulse waveform has not changed at all, and only the amplitude of the ringing has become smaller. The amplitude of this ringing became smaller because its frequency became higher.The reason why only the ringing waveform changed without any change in the shot pulse waveform is as follows. In other words, the rectification method of the tertiary winding 14 is scanning period rectification, and since the load is connected to the tertiary winding, the tertiary winding 14 is only active during the scanning period, that is, the period when ringing occurs. This results in an alternating current short circuit via the capacitor in the rectifier circuit.The tertiary winding 14 that acts in this way is placed close to the secondary winding 17, so this phenomenon inevitably occurs. The leakage magnetic flux of the secondary winding 17 with respect to the primary winding 13 interlinks with this tertiary winding 14. However, as mentioned above, this tertiary winding 14 is Since the tertiary winding 14 is short-circuited, a current flows through the tertiary winding 14 to cancel out the interlinked magnetic flux only during the scanning period.
The leakage magnetic flux that inevitably occurs in the secondary winding 17 is substantially reduced only during the scanning period. On the other hand, the frequency of ringing during the scanning period is the series resonance frequency of the leakage inductance LI of the secondary winding 17 and the stray capacitance Cs, and as is well known, this is the frequency of f=2. Since it is determined by S, as described above, as the leakage magnetic flux of the secondary winding 17 decreases, its resonance frequency, that is, the ringing frequency increases.

As described above, the tertiary winding 14 is short-circuited in AC only during the scanning period, so the amplitude of ringing can be reduced without affecting the shot pulse waveform in any way. Although the configuration and operation and effects of the flyback transformer of the present invention have been described above, the configuration of the flyback transformer of the present invention is not limited to that shown in the second figure.

Rather, what is shown in the second figure is a principle example for explaining the present invention, and the ringing ratio is actually designed in balance with other characteristics of the flyback transformer. The structures shown in Figs. to 10 are more practical, that is, the structure shown in Fig. 5 has a tertiary winding
4 into the winding groove at one end of the low voltage coil bobbin 11.
The secondary winding 17 is formed so as to cover both the primary winding 13 and the tertiary winding 14. In this case, it is desirable to wind the tertiary winding 14 on the lower potential side of the secondary winding 17 in consideration of its withstand voltage. In the case shown in FIG. 6, the tertiary winding 14 shown in FIG.
The one shown in FIG.
In the case where the illustrated tertiary winding 14 is distributed and wound also on the high potential side of the secondary winding 17, in the case shown in FIG. 8, the tertiary winding 14 illustrated in FIG. The bottom of the winding groove has been raised. What is shown in FIG. 9 is a low voltage coil bobbin 11.
In the case where the winding groove in the middle is raised to the bottom and the tertiary winding 14 is formed in that part, the one shown in FIG. It is designed to form a . Although there are some differences in degree, all of these are capable of sufficiently reducing the ringing ratio for the same reason as the one shown in the second figure. Furthermore, in the above embodiments, each winding has been described as having a split winding, but the present invention is not limited to this in any way, and an appropriate winding such as a solenoid winding can be applied. Furthermore,
As in the embodiment shown in FIG.
The magnetic coupling with the secondary winding becomes loose and the 2
Rather than installing it in a position that interlinks with the leakage magnetic flux of the next winding,
As shown in FIG. 11, in which the same machine components as in FIG. It is also possible to have a configuration in which it is connected to. In this case, the dispersion ratio of the tertiary winding close to the 2nd winding and that close to the primary winding is determined to be optimal depending on the overall configuration of the flyback transformer. It should be selected so that the characteristics can be obtained.
In other words, if all of the tertiary windings are provided at a position where the magnetic coupling with the primary winding is loose and the leakage magnetic flux of the secondary winding with respect to the primary winding is linked, the tertiary winding When the load connected to the winding becomes large and the current flowing through the tertiary winding becomes large, the shot pulse waveform induced in the secondary winding becomes as shown in Figure 12, which shows a case where fifth-order tuning is applied. A distortion occurs in which the right shoulder drops, which has a negative effect on high voltage regulation. However, if the tertiary winding is distributed as described above, the tertiary winding Even when the connected load is large, distortion does not occur in the shot pulse waveform and the high voltage regulation does not deteriorate, which is very good. In addition, as the tertiary winding for purposes other than taking out the secondary B power, in the above embodiment, a tertiary winding for signals such as AFC and AGC was illustrated, but the tertiary winding of the flyback transformer according to the present invention is It may also be used solely for the purpose of improving the ringing ratio without being used for signals such as AFC and AOC. The tertiary winding of the flyback transformer according to the present invention is thus configured to have two
Next B: Since it is not used for the purpose of extracting power,
It is also possible to integrate a rectifier circuit connected to the tertiary winding and a load such as an impedance element such as a resistor connected to the rectifier circuit with the flyback transformer.
Various embodiments of the flyback transformer of the present invention have been described above, but the point is that at least a part of the tertiary winding for purposes other than extracting the secondary B power source has a loose magnetic coupling with the primary winding. , and a rectifying element such as a diode which is biased in the forward direction during the scanning period of the horizontal deflection circuit is installed in the tertiary winding at a position interlinking with the leakage magnetic flux of the secondary winding with respect to the primary winding. It is sufficient to connect the load through a rectifier circuit consisting of a smoothing capacitor and a rectifier circuit to perform rectification during the scanning period, and there are various configurations that satisfy this requirement in addition to the above-mentioned embodiments. death,
The present invention includes all of them.

By having the flyback transformer of the present invention configured as described above, only the amplitude of the ringing can be reduced by 4 degrees without affecting the shot pulse in any way, and the adjustment is extremely easy. This provides an excellent effect in that the value of the ringing ratio can be made much smaller than in the past.

Furthermore, when such a flyback transformer is incorporated into a TV receiver, it is possible to extremely reduce unnecessary radiation.

[Brief Description of the Drawings] Fig. 1 is a diagram showing a pulse waveform for explaining the ringing ratio, Fig. 2 is a sectional view of a main part of a flyback transformer according to an embodiment of the present invention, and Fig. 3 4 is a diagram showing the induced waveform of the secondary winding of the flyback transformer, {a) is the one according to the present invention, ' Figures 5 to 11 are partial cross-sectional views of main parts showing other embodiments of the flyback transformer of the present invention, and Figure 12 shows the effect of the load connected to the tertiary winding. It is a figure which shows the induced waveform of the secondary winding for explanation. 11...Low pressure coil bobbin, 12...Core, 13
...Primary winding, 14...Third winding, 15...Insulating material, 16...High voltage coil bobbin, 17...Secondary winding, 18...Horizontal deflection circuit, 19, 20... Rectifier circuit, 21.
··resistance. Figure 1 Figure 2 Figure 3 Figure 4 Figure S Figure 6 Figure B Figure 8 Figure 9 Figure 10 Figure 11 Figure 12

Claims (1)

[Claims] 1 At a position where the magnetic coupling with the primary winding is weak and where the leakage magnetic flux of the secondary winding with respect to the primary winding interlinks, 2
A rectifier circuit consisting of a rectifying element and a smoothing capacitor, which is wound with at least a part of the tertiary winding other than for the purpose of extracting the secondary B power source, and the tertiary winding is biased in the forward direction during the scanning period of the horizontal deflection circuit. A flyback transformer characterized in that a load is connected through.