JPS5932232Y2 - flyback transformer - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a flyback transformer for a television receiver.

In television receivers, especially color television receivers, the anode voltage of the picture tube is a very high value of 20 to 30 KV, and such high voltage remains after the receiver is powered off. This is extremely dangerous during maintenance work such as inspection and repair.

Further, this residual voltage may generate a brightly shining spot near the center of the screen of the picture tube after the power is turned off, giving a sense of uneasiness to the user and damaging the fluorescent side of the picture tube.

In order to solve this problem, various measures have been taken to quickly attenuate the anode voltage of the picture tube after the receiver is powered off.

FIG. 1 shows an example of the prior art. In the figure, 1 is a flyback transformer, 2 is a primary winding, 3 is a first secondary winding of the secondary windings divided into two, and 4 is a primary winding. is the second secondary winding,
5 is a first high voltage diode, 6 is a second high voltage diode, 1 is a picture tube, 8 is an anode electrode, 9 is an equivalent capacitance that the picture tube anode has between the ground, 10 is a power supply, 11 is a power switch, 12 is a high voltage leak resistance.

The anode electrode 80 of the picture tube 7 has a ground capacitance 9 of about 1000 to 2000 PF in a color receiver, and even after the power switch 11 is turned off, a charge remains in this capacitance 9.
A residual voltage of 20-30 KV is maintained.

If the accumulated energy of this charge is large, it is extremely dangerous to receive an accidental electric shock during maintenance or repair.

The high-voltage leak resistor 12 is added for this purpose, and after the power is turned off, the charge on the anode electrode 8 is discharged through the leak resistor 12 and disappears.

However, since this flyback transformer 1 requires a special addition of an expensive high-voltage leak resistor 12, the cost of parts and installation increases due to the labor involved, and the high-voltage leak resistor 12 is usually large. Since it is a component, it requires a large installation space and has disadvantages such as increasing the size of the entire flyback transformer 1.

The object of the present invention is to eliminate the above-mentioned drawbacks, to provide a small and inexpensive flyback transformer that requires fewer man-hours, does not require a high voltage leak resistance.

In order to achieve the above-mentioned purpose, in the present invention, a secondary winding, a secondary winding, and a high-voltage diode are housed in a case.
- A filler made of magnetic powder such as ferrite oxide and synthetic resin is injected into the space including the center hollow part of the next winding, and the insulation resistance value of this filler is equal to that of the DC high voltage output end of the flyback transformer. 1×103Mβ between earths
Or 3×104MQ! We decided to select the following.

FIG. 2 is a sectional view of a flyback transformer showing an embodiment of the present invention, and FIG. 3 is a circuit diagram of a high voltage generation circuit according to this embodiment.

In FIG. 2, 13 is a primary bobbin around which the primary winding 2 is wound;
14 is a secondary bobbin around which the secondary windings 3 and 4 are wound; 15 is a primary winding 2; - secondary bobbin 13; secondary windings 3 and 4; secondary bobbin 1
4. High voltage diodes 5, 6 fixed to the secondary bobbin 14
It is a cast case that stores.

Reference numeral 16 denotes a filler made of magnetic powder and synthetic resin, which is cast into the casting case 15 to fill the primary winding 2 inside the casting case 15.
, the secondary windings 3 and 4, the high voltage diodes 5 and 6, etc., to perform insulation treatment and form a magnetic circuit.

17 is a DC high voltage output lead wire, and 18 is a low voltage side extraction terminal.

In the present invention, since the high-voltage diodes 5 and 6 are also embedded in the filler 16, there is an equivalent connection between the DC high-voltage output terminal a1, that is, the cathode of the high-voltage diode 6, and the earth b, which is determined by the insulation resistance of the filler 16. A leak resistance is formed.

Here, the value of the insulation resistance of the filler 16 forming the equivalent leak resistance is selected so that the resistance value between the DC high voltage output terminal a and the earth b is 1×10 3 Mβ to 3×10′ M,O.

19 is the equivalent leakage resistance caused by the filler 16 directly between the DC high voltage output terminal a (high voltage diode 60 cathode) of the flyback transformer 1 and the ground b (start of secondary winding), and 20° and 21 are the seven. This shows the equivalent leakage resistance generated between the anode and cathode of the high voltage diodes 5 and 6.

These three typical equivalent leak resistances 19, 20°21
As a result, a required total leak resistance is formed between the DC high voltage output terminal a and the ground b.

In the present invention, since the leak resistance is formed by the filler 16, in addition to the leak resistance 19, 20.21, there are many discharge paths for residual charge, that is, leak resistance, between each electrode inside the casting case 15. Of course, it can be assumed, and the above three are representative ones.

The value of the total leak resistance R between the DC high voltage output terminal a and the earth b is determined from the discharge extinction time of the residual voltage, that is, the discharge time constant.

In order to prevent the risk of electric shock to users, maintenance personnel, etc., it is desirable that the discharge time constant of the picture tube be within one minute.

As mentioned above, the capacitance 9 of the anode electrode 8 of the picture tube is 1
000 to 2000PF, it is desirable that the total leak resistance R be as follows.

However, lowering the value of the total leak resistance R increases power loss, which is inconvenient.

It is desirable to suppress the power loss due to the total leak resistance R to less than IW, and the voltage at the high voltage output terminal a is approximately 30 KV at maximum.
Therefore, in order to keep the power loss below IW, the lower limit of the value of the total leak resistance R should be about 1000 M# or more.

As explained above, the present invention eliminates the need for an expensive and large-sized high voltage leak resistor, eliminates the need for installation work and storage space, is small and easy to manufacture, is inexpensive, and allows high voltage to remain after the power is turned off. You can't get a flyback transformer.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a conventional high voltage generation circuit, Fig. 2 is a sectional view showing an embodiment of a flyback transformer according to the present invention, and Fig. 3 is a high voltage generation circuit according to the embodiment shown in Fig. 2. FIG. 2... Primary winding, 4... Secondary winding, 5, 6... High voltage diode, 16... Filler.

Claims (1)

[Scope of utility model registration request] a primary winding; a secondary winding electromagnetically coupled to the primary winding;
In a flyback transformer having a high-voltage diode connected in series to a secondary winding, a magnetic path is formed by a filler made of magnetic powder and a synthetic resin, and the above-mentioned 2.
Between the next winding and ground, 1X103Mβ or more, 3X
A flyback transformer characterized by forming a resistance of 10'MQ or less.