JPS6355311B2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a flyback transformer used in television receivers, etc., and its purpose is to simultaneously reduce the distributed capacitance of the secondary coil and reduce leakage inductance. The present invention aims to provide a flyback transformer with good high pressure regulation, little ringing, and extremely simple design.

Typically, a flyback transformer has a primary coil, a high-voltage secondary coil, and a low-voltage tertiary coil.The high-voltage coil is for supplying the anode voltage and focus voltage of the cathode ray tube, and has several thousand turns. The distributed capacitance between the lines is reduced by dividing the line into individual section coils and connecting them in series via rectifier diodes. Each section coil is wound around the core in a concentric cylindrical shape. In this case, there are two types of section coils: one in which the coil is wound in multiple layers with interlayer insulation, and the other in which it is wound in multiple layers in the winding groove of a split bobbin with multiple flanges. be. FIGS. 3 and 4 show an example of the latter configuration. 17 is a flyback transformer, 18 is a secondary section coil divided into three parts, 19A, 1
Coils 9B are connected in parallel to each other to form a primary coil. Reference numerals 20, 21, and 22 denote low-voltage tertiary coils, which are normally arranged to supply power to a heater of a cathode ray tube or DC voltage to a video circuit, an integrated circuit, or the like. Figure 4 shows the structure of a flyback transformer in which these coils are wound. 23 is a low voltage bobbin, and the primary coil and low voltage tertiary coils 20, 21, 22 are connected to each other.
are mixed together and wrapped 24. A high voltage bobbin 25 is wound with a high voltage secondary coil 26.

What is particularly important in the performance of a flyback transformer is the degree of fluctuation of the high voltage output voltage due to changes in the high voltage load current, so-called high voltage regulation, which mainly affects the amplitude fluctuation of the screen, and the degree of fluctuation of the high voltage output voltage due to changes in the high voltage load current. It is known that this causes a vertical image of the brightness and darkness of the screen. High voltage regulation worsens as the leakage inductance between the primary and secondary of the flyback transformer increases, while ringing is caused by harmonic resonance formed by this leakage inductance and the distributed capacitance of the secondary coil. It is well known to do so.
As already mentioned, it is effective to divide the secondary coil into a plurality of section coils and connect them in series via rectifier diodes in order to reduce the distributed capacitance of the secondary coil. On the other hand, in order to reduce the leakage inductance of the primary coil and the secondary coil, a good method is to wind the primary coil and the secondary coil closely in a concentric cylindrical shape and to make the winding widths approximately equal. However, since the secondary coil has a large number of turns and a high voltage, there is a natural limit to winding it sufficiently close to the primary coil. Moreover, as is clear from FIG. 4, the low voltage bobbin 12 is wound with a large number of low voltage tertiary coils in addition to the primary coil, and the number of lead wires drawn out from the low voltage bobbin 12 increases. As a result, the dimensions between the primary coil and the secondary coil become wider, the coupling becomes looser, and the leakage inductance increases. More importantly, because the secondary coil is divided into multiple section coils for the purpose of reducing the distributed capacitance, the winding width of each section coil becomes narrower than that of the primary coil. Generally speaking, this increases the leakage inductance of the primary coil and the secondary coil, and is a major obstacle to easily realizing good high voltage regulation and low linking. For this reason, a great deal of design time and effort is required in the design of flyback transformers and, further, in the design of television sets, resulting in an increase in the cost of circuit countermeasures.

The present invention eliminates the above-mentioned conventional drawbacks, and the structure of the present invention will be explained below with reference to the drawings showing embodiments.

1 is a horizontal output transistor, 2 is a damper diode, 3 is a resonant capacitor, 4 is a horizontal deflection coil, 5 is an S-shaped correction capacitor, 6 is a flyback transformer, and 7A, 7B, 7C, and 7D are coils forming the primary coil. In the present invention, the primary coil is composed of at least three coils connected in parallel. Reference numeral 8 denotes a plurality of divided section coils constituting a high-voltage secondary coil, which are connected in series via rectifier diodes to reduce distributed capacitance. Reference numerals 9, 10, and 11 are low-voltage tertiary coils for supplying electric power to the heater of the cathode ray tube or DC voltage to the video circuit, etc. As shown in FIG. 2, each section coil 8 is wound 13 in a winding groove of a high-voltage bobbin 12 having a plurality of flanges. 14
1 shows a state in which any one parallel coil 7D among the plurality of coils constituting the primary coil and all the low voltage tertiary coils 9, 10, 11 are wound close to each other, and the secondary coil is wound at a position other than the inner circumference of the high-pressure bobbin 12 (in the case of FIG. 2, below the high-pressure bobbin). 15 is a low-pressure bobbin, and on this low-pressure bobbin 15 other parallel coils 7A, 7B, and 7C constituting the primary coil are connected to the core 16.
The secondary coil is wound in the axial direction of the secondary coil, and is located on the inner periphery of the high-voltage bobbin 12 around which the secondary coil is wound.
The number of primary parallel coils wound around the inner circumference of the high voltage bobbin 12 increases as the number of section coils constituting the high voltage secondary coil increases. Since the widths approach the same direction, the leakage inductance can be reduced. Furthermore, because the diameter of the primary parallel coil can be made smaller and the winding thickness can be reduced, the collar of the low-pressure bobbin is much lower than that of conventional ones, and the distance between the primary and secondary coils is closer. In this way, the leakage inductance of the primary coil and secondary coil can be significantly reduced. On the other hand, regarding the primary parallel coil 7D and the low-voltage tertiary coil wound below the high-voltage bobbin, the low-voltage tertiary coils 9, 10, and 11 have a low degree of magnetic coupling with the secondary coil, but a low degree of coupling with the primary coil. It is easily understood that since the voltage is high, the superposition of the ringing voltage is extremely small, and the voltage stability of these tertiary coils is extremely good.

Although FIGS. 1 and 2 show an embodiment in which the secondary coil is wound in sections, the present invention is not limited to this, and the same configuration can be applied to the multi-layered flyback transformer described above. .
However, in the latter case, the section coil that makes up the secondary coil is usually wound over the entire length of the high-voltage bobbin, so the number of primary parallel coils arranged around the inner circumference of the high-voltage bobbin is limited. One piece is enough. Moreover, one of the low-voltage tertiary coil and the primary parallel coil can be arranged in separate legs of the magnetic core.

As described above, in the present invention, the high-voltage secondary coil is divided into section coils via diodes, so the distributed capacitance is small. One of the coils and the tertiary coil are wound close to each other except for the inner circumference of the secondary coil, and the remaining parallel coils are wound around the inner circumference of the secondary coil, so the primary coil The collar of the bobbin on which the coil is wound can be lowered, which allows the primary and secondary coils to be close to each other and are wound with a narrow winding width, reducing the leakage inductance between the primary and secondary coils. , the frequency of the harmonics becomes significantly higher and the amplitude decreases, resulting in less ringing. As a result, high pressure regulation can be significantly improved. In addition, the pulse voltage generated by the low-voltage tertiary winding has less superimposition of ringing voltage, improves voltage stability, and requires almost no detailed design adjustments, making it extremely simple.
It has extremely useful effects industrially.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of a flyback transformer according to the present invention, Fig. 2 is a sectional view of the same essential part, Fig. 3 is a circuit diagram showing an example of a conventional product, and Fig. 4 is a circuit diagram showing an example of a flyback transformer according to the present invention.
The figure is a sectional view of the same main part. 7A, 7B, 7C, 7D...Parallel coil, 8...Section coil, 14...Wound state.

Claims (1)

[Claims] 1. A primary coil, a high-voltage secondary coil, and a low-voltage tertiary coil are arranged around the outer periphery of the core, the primary coil is composed of a plurality of parallel coils, and the secondary coil is composed of a plurality of section coils. In a flyback transformer configured by connecting in series through a rectifier diode, one parallel coil of a plurality of parallel coils constituting the primary coil and the tertiary coil are connected to the inner circumference of the secondary coil. A flyback transformer characterized in that the coils are wound close to each other at positions other than the primary coil, and another parallel coil of the plurality of parallel coils constituting the primary coil is wound around the inner periphery of the secondary coil. . 2. A plurality of section coils constituting a high-voltage secondary coil are wound in winding grooves of a split bobbin having a plurality of flanges, and the above-mentioned section coils are wound together with a low-voltage tertiary coil among at least three or more parallel coils constituting a primary coil. The parallel coils other than the one parallel coil wound close to each other at positions other than the inner periphery of the secondary coil are arranged and wound around the inner periphery of the secondary coil in an orderly manner in the axial direction of the core. A flyback transformer according to claim 1, characterized in that: