JPH0218026B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flyback transformer for supplying high voltage to a cathode ray tube anode of a television receiver.

Generally, in a flyback transformer, a predetermined high voltage is obtained by boosting the pulse voltage generated by the switching operation and the L and C resonance circuits using a high voltage coil and rectifying it using a rectifier diode. It is known that the pulse voltage is generated during the retrace period, but due to distributed capacitance and leakage inductance, it becomes a high frequency much higher than the fundamental wave of the flyback pulse, and is superimposed on the pulse as ringing. It is being This ringing energy then spreads to various parts of the television circuit through capacitive coupling or electromagnetic coupling, and as a result, bright and dark vertical stripes appear on the screen of the cathode ray tube, causing a decline in image quality.
This causes inconveniences such as unnecessary current flowing through the high-voltage coil and causing a rise in temperature. Eliminating such inconveniences, in other words, obtaining a flyback transformer that does not cause ringing, will lead to good image quality characteristics. This was strongly desired from the viewpoint of safety and the availability of the product.

On the other hand, in recent years, as shown in FIG. 1, a flyback transformer has been developed in which a high-voltage coil 1 is divided into a plurality of (four in the drawing) winding sections 1a, 1b, each having an approximately equal number of turns.
Divided into 1c and 1d, between each winding section 1a to 1d,
Then, rectifier diodes 2a, 2b, 2c, and 2d are connected in series to the output side of the final winding section 1d, and each winding section 1a to 1d of the high voltage coil 1 is wound on the core 3 via an insulating layer S. Turned primary coil 4
A structure in which the core 3 is sequentially laminated and wound concentrically around the core 3 has been developed and put into practical use. In the case of such a configuration, since the coupling between each layer (winding sections 1a to 1d) of the high voltage coil 1 is extremely good, and there is no AC potential between each layer,
A loop for causing ringing is not formed between each of the winding sections 1a to 1d, and ringing occurs only between the winding section 1a on the starting end side (first layer) of the high voltage coil 1 and the primary coil 4.

Conventionally, in order to eliminate such ringing, as shown in FIG. It was caused by consuming ringing energy.

However, in such a configuration, the resistor 5
The ringing energy is consumed and the ringing is attenuated by In addition, the ringing energy may be concentrated on the resistor 5, causing the resistor 5 to generate heat.

The present invention relates to a flyback transformer intended to eliminate the above-mentioned drawbacks, and particularly to a flyback transformer having a configuration that consumes ringing energy generated in the flyback transformer without losing the fundamental pulse of the flyback transformer. It is something.

Hereinafter, one embodiment of the flyback transformer of the present invention will be described in detail with reference to the drawings. In FIG. 2, a primary coil 12 is wound around the outer periphery of the core 11 in a wide manner, and a high voltage coil 13 is wound around the outer periphery of the primary coil 12 into four winding sections 13a, each having a substantially equal number of turns.
13b, 13c, and 13d, and each winding section 13a to 13d is sequentially wound around the core 11 (primary coil 12) in a concentrically laminated state with an insulating layer S interposed therebetween. Rectifier diodes 14a, 14b, 14c, and 14d are connected in series between each winding section 13a to 13d of the high voltage coil 13 and on the output side of the final winding section 13d, respectively.
A high voltage output is obtained from the output end of the rectifier diode 14d. Here, among the winding sections 13a to 13d constituting the high voltage coil 13, the primary coil 1
The starting end side where ringing occurs between 2, that is,
A winding section 13a wound on the innermost circumference adjacent to the primary coil 12 has a number of turns approximately equal to the number of turns of the winding section 13a, and a resistance value higher than that of the winding section 13a. For example, ringing removal means RC equipped with a ringing removal coil 15 made of high resistance wire, fine wire, etc. are connected in parallel, and the ringing removal coil 15 of the ringing removal means RC is connected to the inner circumference of the winding section 13a. , winding section 1
3a and the primary coil 12, and is wound around the core 11.

FIG. 3 shows another embodiment of the ringing removal means RC of the flyback transformer of the present invention, in which the ringing removal coil 15 is connected in series to the ground side of a ringing removal coil 15 made of ordinary copper wire (of the same type as the high voltage coil 13). A ringing removal means having a resistance value higher than the resistance value of the winding section 13a by connecting a resistor 16 to the winding section 13a.
It is composed of RC and is a means for removing ringing.
Of the RC, the ringing removal coil 15 is wound on the core 11 while being sandwiched between the winding section 13a and the primary coil 12 as described above,
is integrated (built-in) into the flyback transformer,
Alternatively, it is provided separately (externally attached).

In a flyback transformer with such a configuration,
Each layer of the high voltage coil 13 (winding sections 13a to 13
By making the number of turns of d) approximately equal and concentrically stacking the primary coil 12 wound around the core 11, the coupling between each layer of the high-voltage coil 13 is improved. Since there is no AC potential between each layer, no loop is formed between each winding section 13a to 13d to cause ringing, and the winding section 13a on the starting end side of the high voltage coil 13 and the primary Between the coils 12, as a ringing removing means RC, a ringing removing coil 15 having approximately the same number of turns as the winding section 13a is connected in parallel to the winding section 13a. The same voltage waveform as in winding section 13a is induced, and no current flows through the distributed capacitance between winding section 13a and ringing removal coil 15, so winding section 1
3a and the ringing removal coil 15, a loop for causing ringing is not formed (that is,
The area between the high voltage coil 13 and the primary coil 12 is shielded by the ringing removal means RC),
Ultimately, a ringing loop is formed by the distributed capacitance between the ringing removal coil 15 and the primary coil 12 that constitute the ringing removal means RC, and ringing occurs. It is consumed by the DC resistance component and the ringing is attenuated. Here, the current flowing through the winding section 13a on the starting end side of the high voltage coil 13 and the current flowing through the ringing removal means RC (ringing removal coil 15) are determined by the resistance value of each coil. The ringing removing coil 15 of the ringing removing means RC is made of a high-resistance wire or a thin wire, or a resistor 16 is connected in series to the ground side of the ringing removing coil 15, so that the ringing removing coil 15 of the ringing removing means RC is removed in advance. Since the resistance value of is set higher than the resistance value of the winding section 13a, the current flowing through the ringing removal coil 15 (ringing removal means RC) is smaller than the current flowing through the winding section 13a. As a result, most of the basic pulse current of the flyback transformer flows through the winding section 13a and is not consumed or lost, and almost no power loss occurs.

In addition, in one embodiment of the flyback transformer of the present invention, a high-voltage coil is divided into four winding sections having approximately the same number of turns. However, the number of divisions of the high-voltage coil is limited to the embodiment. The number of rectifying diodes can be increased or decreased according to the increase or decrease in the number of divided high-voltage coils. Also,
The winding shape of the high voltage coil and the primary coil is arbitrary, and for example, it may be wound in a section shape using a section bobbin.

As described above, according to the flyback transformer of the present invention, a high-voltage coil is divided into a plurality of winding sections having approximately the same number of turns, and a rectifier diode is connected in series between each winding section and on the output side of the final winding section. In a flyback transformer in which each winding section is sequentially laminated and wound concentrically around a core around which a primary coil is wound, the winding section on the starting end side of the high voltage coil has at least the number of turns of the winding section. A ringing removing coil having a number of turns approximately equal to , and a ringing removing coil having a resistance value higher than that of the winding section on the starting end side are connected in parallel, and the ringing removing coil of the ringing removing means is connected to the starting end of the high voltage coil. The coil is wound between the side winding section and the primary coil, and the high voltage coil and the primary coil are shielded by the ringing removal means, and the ringing loop is removed between the ringing removal coil and the primary coil. However, the ringing energy is consumed by the resistance component of the ringing removal coil, or the resistance component of the ringing removal coil and the resistance component of the resistance connected in series with the ringing removal coil, and is efficiently attenuated. This makes it possible to obtain a flyback transformer with ringing eliminated.
In addition, by placing a ringing removal coil with approximately the same number of turns as the winding section of the high-voltage coil between the winding section on the starting end side of the high-voltage coil and the primary coil, the ringing removal coil is placed between each winding section of the high-voltage coil and There is no distributed capacitance between the winding section on the starting end side and the ringing removal coil, and a ringing loop is not formed. The ringing loop is moved between the ringing removal coil and the primary coil, so there is no need to provide a ringing removal means for each winding section of the high voltage coil, and the ringing loop is simply moved between the ringing removal coil and the primary coil. Ringing can be reliably removed simply by providing a ringing removing coil of the ringing removing means between the line section and the primary coil. Furthermore, by connecting a ringing removal means having a resistance value higher than the resistance value of the winding section in parallel to the winding section on the starting end side of the high voltage coil, most of the basic pulse current of the flyback transformer is removed by the ringing removal means. The basic pulse of a flyback transformer is almost never lost, compared to a conventional high-voltage coil constructed by connecting a resistor in series with the winding section. Power loss is also extremely reduced. Here, it is possible to consider a method of shielding ringing by inserting a resistor connected in series to a plate-shaped conductor between the primary coil and the high-voltage coil in the same way as a ringing removal coil, but in this case, compared to the present invention, The current flowing through the conductor increases, and the loss of fundamental pulses also increases. In addition, in the present invention, by configuring a part of the ringing removal means using a wound coil, eddy current loss with respect to the fundamental pulse is reduced compared to a case where the ringing removal means is configured using a plate-shaped conductor. Basic pulse loss and power loss are also reduced. Another way to selectively flow only the basic pulse current is to connect a parallel circuit of a resistor and coil in series to the start end (low voltage end) of the high voltage coil, but in this case, the resistor and coil are connected to the high voltage coil. Since it is connected in series with the base pulse, the impedance to the fundamental pulse current increases and the leakage inductance increases. In contrast, according to the configuration of the present invention, the ringing removal means is connected in parallel with the high-voltage coil, and there is no increase in impedance or leakage inductance with respect to the basic pulse current. Furthermore, the consumption of ringing energy is distributed over the entire ringing removal means, so there is no concern that abnormal heat generation will occur on the circuit, and it is highly safe. As described above, according to the flyback transformer of the present invention, ringing can be removed with an extremely simple configuration, and good image quality characteristics can always be obtained, making it particularly effective as a high-performance flyback transformer. be.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional flyback transformer, FIG. 2 is a sectional view of a flyback transformer according to an embodiment of the present invention, and FIG. 3 is a configuration circuit diagram of another embodiment of the present invention. 11...Core, 12...Primary coil, 13...High voltage coil, 13a to 13d...High voltage coil winding section, 1
3a... Starting end side winding section, 14a to 14d... Rectifier diode, RC... Ringing removal means, 15... Ringing removal coil, 16... Resistor.

Claims (1)

[Scope of Claims] 1. A high-voltage coil is divided into a plurality of winding sections having approximately the same number of turns, and a rectifier diode is connected in series between each winding section and on the output side of the final winding section, and each of the winding sections is In a flyback transformer in which a primary coil is sequentially wound concentrically in a laminated manner around a core, a winding section on the starting end side of the high voltage coil has at least a number of turns approximately equal to the number of turns of the winding section. Ringing removal means having a ringing removal coil having a resistance value higher than that of the winding section on the starting end side are connected in parallel, and the ringing removal coil of the ringing removal means is connected in parallel to A flyback transformer characterized by having a winding arranged between a winding section and a primary coil. 2. The flyback transformer according to claim 1, wherein the ringing removing means is comprised only of a ringing removing coil having a resistance value higher than the resistance value of the winding section on the starting end side of the high voltage coil. 3. The flyback transformer as claimed in claim 1, wherein the ringing removing means comprises a ringing removing coil and a resistor connected in series to the ground side of the ringing removing coil.