JPS5915164B2 - flyback transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flyback transformer used in a high voltage generating circuit such as a television receiver.

In television receivers and the like, it is common practice to provide an auxiliary winding in a flyback transformer to take out a positive or negative pulse voltage, and to supply this pulse voltage to various circuits for use. In this case, the voltage induced in the auxiliary winding is about 5 to 10 Vp,p per turn, so when obtaining a relatively low output voltage (for example, 70 to 100 Vp-p or less), the value of the output voltage is The problem is that only discrete values of integral multiples of the induced voltage per turn can be obtained. For example, when directly igniting a picture tube heater using the output voltage of an auxiliary winding installed in a flyback transformer, a voltage of 6.3 V is required in terms of effective value. When the auxiliary winding is constructed as a single winding body, the output voltage is an effective value of 5.5 V to 5.9 V, and it is not possible to obtain 6.3 V when the number of turns is 3 turns. Ta. Further, when the number of turns was 4, the voltage was 7.3V to 7.9V, which was higher than 6.3V, and 6.3V was still not obtained. In addition,
In the above description, the output voltage of the auxiliary winding is shown within a certain range because even if the number of turns of the auxiliary winding is the same, the induced voltage value differs somewhat depending on the position at which the auxiliary winding is wound.
0 Conventionally, when a predetermined voltage value cannot be obtained as the output voltage of the auxiliary winding, the auxiliary winding is set to obtain an output voltage higher than the predetermined voltage value, and the output voltage is controlled by a resistor. It is used by lowering the voltage to the specified voltage.

However, since this method uses 15 resistors, not only does power loss increase, but when igniting the heater of the picture tube, the heater heating up time becomes longer, and the image output time becomes longer in the case of a quick-start picture tube. This is a fatal flaw. (20) The present invention has been made in view of the above points, and its object is to provide a flyback transformer configured so that a desired output voltage can be easily obtained from the auxiliary winding.

The present invention is based on the fact that the voltage induced in the auxiliary winding is slightly different depending on the position at which the auxiliary 25 winding is wound.

Possible causes of this are the influence of the high voltage coil, the influence of the air gap, etc. According to experiments, the induced voltage tends to increase as the winding position of the auxiliary winding moves away from the air gap of the core, and the number of turns of the primary winding wound above the auxiliary winding increases. When the number of turns is relatively large, the induced voltage has a waveform close to the waveform of the pulse voltage generated in the primary winding, as shown in Figure 4b, but as the number of turns in the primary winding decreases, the voltage increases as shown in Figure 4a. The waveform is affected by the high-voltage coil, resulting in a difference in voltage value. For example, the first
As shown in the figure, in the divided bobbin 1 for a low voltage coil placed inside the divided bobbin 2 for a high voltage coil, the winding distribution of the primary winding does not change, and the number of turns of the auxiliary winding is kept constant. A comparison of the induced voltages when winding the sections 1, . . . at respective positions is as shown in FIG. 2. In the same figure, L,,...,LV
I indicates the auxiliary windings wound around the section portions 1, . . . , respectively. The flyback transformer of the present invention has an auxiliary winding composed of two windings A and B wound at different positions as shown in FIG. As shown in the figure, they are connected so that their respective induced voltages cancel each other out, that is, the winding directions are opposite to each other.

In the figure, windings A, . . . , E wound around the section portions 1, . According to the present invention, by appropriately selecting the number of turns and the winding position of each of the windings A and B, the output voltage value of the auxiliary winding can be adjusted over a very delicate range.

In other words, when the auxiliary winding was constructed as a single winding body as in the past, the output voltage could only take a value that was an integral multiple of the induced voltage per turn, but when constructed as in the present invention, , in addition to the above value as the output voltage of the auxiliary winding, the difference Δ in induced voltage per turn between winding A and winding B
It can also take a value that is an integral multiple of E. The voltage ΔE, which is the difference between the induced voltages mentioned above, can be finely adjusted by changing the winding positions of the windings A and B. Therefore, as mentioned above, by appropriately selecting the number of turns and the winding position of each of windings A and B, it is possible to obtain a desired voltage value without using a dropper resistor as in the conventional case. can. As explained above, the flyback transformer of the present invention has windings A and B, each of which has an auxiliary winding wound an appropriate number of times at different positions, so that the winding directions are opposite to each other. It is connected and configured.

Therefore, as described above, the output voltage of the auxiliary winding can be finely adjusted over a very wide range. Therefore, unlike conventional flyback transformers of this type, there is no need to use a dropper resistor to extract a specified voltage from the auxiliary winding, so all the inconveniences of using a dropper resistor are solved. be done.

[Brief explanation of the drawing]

FIG. 1 is a drawing for explaining the configuration of an auxiliary winding in a flyback transformer embodying the present invention, and FIG.
A drawing showing the relationship between the winding position of the winding and the induced voltage, FIG. 3 is a drawing showing the connection of the windings A and B in the flyback transformer shown in FIG. 1, and FIGS. It is a drawing showing the radio waveform induced in the auxiliary winding. In the figure, 1 is a divided bobbin for the low voltage coil, 2 is a divided poppin for the high voltage coil, A, B are the windings that make up the auxiliary winding, A, 口, C, 2, and H are the windings that make up the low voltage coil. show.

Claims (1)

[Claims] 1. In a flyback transformer in which an auxiliary winding is provided to obtain a relatively low output voltage, the auxiliary winding is
A flyback transformer characterized in that windings A and B are wound a predetermined number of times at positions with different induced voltages per turn, and are connected so that the winding directions are opposite to each other.