JPS6031426Y2 - flyback transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a flyback transformer for use in television receivers, etc., which allows a predetermined DC voltage lower than a high voltage output to be directly obtained.

A flyback transformer has a high-voltage coil that absorbs the pulses generated during the horizontal retrace period of a television signal and uses that energy effectively, and can extract the high voltage necessary for the acceleration voltage of cathode ray tubes. It is normal for it to look like this.

By the way, in order to operate a cathode ray tube, in addition to the above-mentioned accelerating voltage, a DC voltage for focusing is usually required, and this voltage is lower than the high voltage for accelerating.
So-called medium voltage is required.

Therefore, conventionally, a method has been widely adopted in which this medium voltage is divided and extracted from the high voltage for acceleration.

FIG. 1 shows an example of a flyback transformer circuit using such a method of dividing a high voltage to take out a medium voltage.

In the figure, 1 is the core of a flyback transformer, 2 is a low-voltage coil connected to a horizontal output transistor (not shown), etc., to which horizontal deflection current is supplied, and 3-1
．． 3-2.3-3 is a high-voltage coil wound in three groups; 4-1.4-2.4-3 is a high-voltage rectifier diode also provided in three groups; 5- 1.5-2.
5-3 is a high voltage bleeder resistor for voltage division.

Note that EHV is high voltage for accelerating the electron beam of a cathode ray tube, v
M represents a medium voltage for focusing, and a dot attached to one end of each coil represents the polarity of the coil.

When the horizontal output transistor is driven by the horizontal synchronization pulse, current flows through the low voltage coil 2, and a large pulse (flyback pulse) is generated every horizontal retrace period, and the high voltage coil 3-1.3-2.3-3 A high voltage appears.

This pulsed high voltage is applied to the diode 4-1.4-2.4
-3 and rectified, and a DC high voltage EHV is obtained.

This high voltage E) (V is supplied to the accelerating electrode of the cathode ray tube,
High voltage E with no ripples is smoothed by the capacitance between the accelerating electrode and the graphite film connected to ground.
It becomes HV and accelerates the electron beam.

Also, from this high voltage E) IV, the bleeder resistor 5-1
．． A bleeder current flows through 5-2.5-3 to stabilize the voltage.

Therefore, among these resistors, for example, resistors 5-1 and 5-
From the connection point 2, a medium voltage vM having a predetermined voltage lower than the high voltage E, 4v is taken out.

The voltage value of the medium voltage VM taken out at this time is the resistor 5-
Resistance 5-2.5- for resistance value of 1.5-2.5-3
Needless to say, it is determined by the ratio of the resistance values of 3.

If the resistor 5-3 is set as a variable resistor, the medium voltage ■2
can be correctly adjusted to a predetermined value.

With this kind of circuit, the high voltage E for accelerating the cathode ray tube
It is possible to obtain a medium voltage VM for HV and focus, but for this purpose, a resistor 5-1.5-2.5-3 for voltage division is required.
etc. are now required.

Since high voltage E)IV, which is the acceleration voltage of the cathode ray tube, is applied to these resistors 5-1, they must be able to withstand this voltage, and in addition, the heat generated by the bleeder current flowing there cannot be ignored. It is necessary to have a large-sized device with sufficient consideration given to heat dissipation, which causes a large increase in cost, and has the drawback of being undesirable from an energy-saving perspective.

In addition, in recent years, various improvements have been made to flyback transformers to improve their characteristics, and good high-voltage regulation characteristics have been obtained even in a small range of load current values.

When such a flyback transformer is used, the high-voltage bleeder resistor that was required in the past is essentially unnecessary, but in the circuit shown in Figure 1, it is necessary only to take out the medium voltage VM This requires the relatively expensive resistors 5-1 to 5-3, making the cost disadvantage even more unacceptable.

In order to eliminate this drawback, for example, a flyback transformer circuit as shown in FIG. 2 is known.

In the conventional circuit shown in Fig. 2, a flyback transformer with improved high voltage regulation is used, and the bleeder resistor 5-1.5-2゜5-3 in Fig. 1 is removed accordingly. , instead of medium voltage V
Using resistors 5-4 and 5-5 for voltage division to take out M, one end of resistor 5-4 is connected to the cathode side of diode 4-1, and the DC rectified by diode 4-1 is A capacitor 6 is provided for smoothing the voltage, and other points are the same as the circuit shown in FIG.

In this circuit, high voltage coil 3-1.3-2.3-
By appropriately selecting the number of turns of diode 4-1, a DC voltage slightly higher than the focus voltage of the cathode ray tube can be immediately obtained from the cathode side of diode 4-1, so this should be divided into a predetermined value by resistors 5-4 and 5-5. The required medium voltage ■2 can be taken out if the high voltage bleeder resistor 5-1 to 5-3 is used.
(FIG. 1), all the drawbacks of the circuit of FIG. 1 can be eliminated.

However, in the circuit of FIG. 2, the DC voltage obtained on the cathode side of the diode 4-1 is high voltage EHV.
Not smoothed like .

Therefore, it is necessary to add a smoothing capacitor 6,
The drawback is that extra parts are required, which inevitably increases costs and reduces reliability.

The purpose of the present invention is to provide a flyback transformer that eliminates the drawbacks of the prior art described above, eliminates the need for high-voltage bleeder resistors and extra smoothing capacitors, and eliminates the problems associated with their presence. There is something to do.

In order to achieve this purpose, the present invention has a structure in which an auxiliary coil is wound on a part of the bobbin on which the high voltage coil is wound, and a smoothed medium voltage is obtained from the auxiliary coil. Features.

First, before describing embodiments of the present invention, a flyback transformer circuit using a DC medium voltage output auxiliary coil, which is the basis of the present invention, will be described.

In Figure 3, core 1, low voltage coil 2, high voltage coil 3
-1.3-2.3-3, rectifier diode 4-1.4-
2.4-3, resistor 5-4, 5-5, etc. are the same as in the conventional example shown in FIG. 1 or 2.

Reference numeral 7 denotes an auxiliary coil wound on the same bobbin as the high-voltage coils 3-1 to 3-3.One terminal at the beginning or end of the winding is connected to point C on the cathode side of the diode 4-1, and the other terminal is connected to the point C on the cathode side of the diode 4-1. The terminal is connected to the upper end point N of the resistor 5-4 to take out the medium voltage VM.

At this time, the polarities of the high voltage coils 3-1 to 3-1 and the auxiliary coil 7 are aligned as shown in the figure.

Next, the operation of this circuit will be explained with reference to the waveform diagram of FIG.

The symbols attached to each waveform in FIG. 4 indicate the voltage waveform at each point labeled with an alphabet in FIG. 3.

As is clear from this waveform diagram, each high voltage coil 3-1~
A large pulse is generated during the flyback pulse period at the upper end, resulting in waveforms VB-VD and VF, but at the same time, at the lower end of the high-voltage coil 3-2, 3-3, a waveform ■ appears.

,■. It can be seen that a negative pulse is generated as shown in .

This is because the lower ends of the high-voltage coils 3-1 to 3-1 are isolated from the ground by the diodes 4-1, 4-2, and these high-voltage coils 3-2, 3-
3, it can be considered that an electrical neutral point exists in the middle of the coil winding.

Therefore, if the voltage is extracted from the middle of the coil winding of these high voltage coils 3-2, 3-3, a smoothed DC voltage (medium voltage ■2 lower than the high voltage EHv) can be obtained. I understand.

However, providing a tap in the middle of a coil winding such as high voltage coil 3-2, 3-3 poses difficulties in winding work and tends to increase costs. The electrical neutral point moves significantly due to changes in current, and as a result, large ripples appear in the medium voltage VM due to changes in the brightness of the image projected on the cathode ray tube, resulting in a noticeable drawback of unstable focus. was.

Therefore, if the auxiliary coil 7 for DC medium voltage output is provided with the polarity shown, the voltage induced in this auxiliary coil 7 will cause N
The potential at the point can be brought closer to the potential at point D from the potential at point 0. Therefore, by appropriately selecting the number of coil turns of the auxiliary coil 7, the potential at point N can be brought closer to the electrical center of the high voltage coil 3-2. This can be made equivalent to the point N, and a smoothed DC medium voltage (8) can be obtained at the N point.

Therefore, if the voltage VN at point N is divided into predetermined voltages by resistors 5-4.5-5, the necessary medium voltage 2 can be obtained with sufficient smoothness, and therefore, as in the conventional example shown in Fig. 2, capacitor 6
There is no need to provide one.

Moreover, by appropriately selecting the coupling state between the auxiliary coil 7 and the high-voltage coil 3-2, the influence of the load current of the high-voltage EHV can be reduced, and the disadvantage of unstable focusing can be eliminated.

By the way, the high voltage coil 3-1°3-2.
The high-voltage coil assembly of a flyback transformer in the form of a diode multi-segmented high-voltage coil in which 3-3 is divided into a plurality of groups and these groups are electrically separated by diodes 4-1 and 4-2 is as follows: , for example, has a structure as shown in FIGS. 5 and 6.

In the figure, 8 is a split-wound high-voltage coil bobbin, which has a cylindrical body with a disc-shaped collar and has the necessary number of winding grooves 9-1 to 9-.
9 and are divided into a plurality of groups by these winding grooves 9-1 to 9-9.
Each group is configured to form a partition portion for further dividing each group into sections.

Therefore, in the conventional flyback transformer shown in FIGS. 1 and 2, for example, the high voltage coil 3-1 is placed in the winding groove 9-1. The high voltage coil 3-2+ is wound in the grooves 9-4.9-5.9-6 of the second group, and the high voltage coil 3-3 is wound in sections.
are respectively wound around the grooves 9-7.9-8.9-9 of the third group.

A diode 4-1.4-2.4-3 is provided between these high voltage coils 3-1.3-2.3-3.

The present invention relates to a specific configuration of an auxiliary coil in a flyback transformer having such a high-voltage coil assembly.
The diagram will be explained.

Figure 7 shows an embodiment of the flyback transformer according to the present invention, which includes a high voltage coil 3-1.3-2.3-3 and a diode 4.
-1.4-2.4-3, and winding grooves 9-1 to 9-3 divided into three groups. 9-4~9-6.9-7~9-
The split-wound high-voltage coil bobbin 8 having the number 9 is the same as the conventional example shown in FIGS. 5 and 6.

In the figure, the auxiliary coil 7 for DC medium voltage output is wound in the winding groove 9-4, and the wire at the beginning of the winding is connected to the cathode of the diode 4-1, and the wire at the end of the winding is separately connected. It is connected to the terminal T, which is connected to the terminal T, to take out the medium voltage VM.

That is, in the embodiment shown in FIG. 7, one of the winding grooves adjacent to the high voltage coil 3-2, that is, the winding groove 9-4, is used for winding the auxiliary coil 7.

As a result, a voltage corresponding to point N in Figure 3 is output from terminal T.
, is obtained, and by dividing this with a resistor 5-4.5-5 (Figure 3), a smoothed DC medium voltage M is obtained, using a high voltage bleeder resistor and an extra smoothing capacitor. This method can be reliably obtained without any problems, and the drawbacks of the prior art can be fully eliminated.

Here, the number of turns required for the DC medium voltage output auxiliary coil 7 varies depending on the state of the waveform ■c at the 0 point in FIG. Over a fairly wide range of 1 to 3 times the number of turns of the high voltage coils 3-1 and 3-2, 10 to 3 times the number of turns of the high voltage coil 3-2.
It has been experimentally found that it is within 0%.

For example, if the number of windings of the high voltage coil 3-1.3-2.3-3 is 3000 turns in total, about 330 turns are wound in each of the winding grooves 9-1 to 9-1.

Therefore, even if the auxiliary coil 7 is required to have the maximum number of turns, it will be 300 turns, which is 30% of 1000 turns.
As in the embodiment shown in FIG. 7, the wire can be sufficiently accommodated in one winding groove 9-4, and the auxiliary coil 7 can be wound in exactly the same way when winding the high-voltage coil 3-1. Therefore, the cost increase in winding work can be almost ignored.

The number of turns required for the auxiliary coil 7 is the high voltage coil 3-
Since it does not reach 1 to 10% of the total, the cost increase due to this is quite small, and can be reduced to less than half of the cost increase due to the addition of the capacitor 6 in the conventional example shown in FIG. , the drawbacks of the prior art can be fully eliminated.

By the way, in the embodiment shown in FIG. 7, the auxiliary coil 7 is wound in the groove 9-4 adjacent to the winding groove 9-5 in which the high-voltage coil 3-2 is wound. The high voltage coil 3-2 is wound around 5.9-6, but if the high voltage coil 3-2 cannot be completely wound, the number of grooves may be increased appropriately.

Further, the auxiliary coil 7 does not necessarily have to be provided in the groove 9-4 adjacent to the high-voltage coil 3-2.
The high voltage coil 3-2 may be provided in the grooves 9-4 and 9-6, and the auxiliary coil 7 may be provided in the groove 9-5. , or groove 9-4.
A high voltage coil 3-2 may be provided in the groove 9-5, and an auxiliary coil 7 may be provided in the groove 9-6, thereby controlling the change characteristics of the medium voltage VM (medium voltage regulation characteristics) with respect to the current change of the high voltage EHv. It can be set arbitrarily, thereby giving desired focus tracking characteristics to the operation of the cathode ray tube.

It goes without saying that in this case, consideration must be given to the insulation of the lead wire of the high voltage coil 3-2, compared to the case where the auxiliary coil 7 is provided in the groove 9-4.

FIG. 8 shows another embodiment of the present invention. This embodiment is different from the embodiment shown in FIG. A part of the auxiliary coil 7 and the auxiliary coil 7 are wound in the same groove 9-4 in a separated state.

This spacer 10 is made of a suitable insulating material such as plastic and has a ring shape as shown in FIG.

During winding work, first insert the high voltage coil 3 into the winding groove 9-4.
-2 is partially rolled up, and then the spacer 10 is spread out at the cutting part 11 as shown in FIG. 9 and fitted into the groove 9-4.

After that, the auxiliary coil 7 may be wound.

Note that FIG. 9C shows the spacer 10 viewed from the side.

This embodiment can also be applied to any groove among the grooves 9-4, 9-5, and 9-6, as in the embodiment of FIG. It is necessary to pay sufficient attention to insulation.

According to the embodiment shown in FIG. 8, not only can all the effects of the embodiment shown in FIG. It is possible to obtain the effects of changing the focus tracking characteristics to enable arbitrary focus tracking characteristics, or increasing the number of windings of the high voltage coil 3-2, thereby improving the space factor and enabling miniaturization.

FIG. 10 shows yet another embodiment of the present invention, in which the auxiliary coil 7
A part thereof is housed in the winding groove 9-4 in a bifilar manner with a part of the high-voltage coil 3-2.

According to this embodiment, the auxiliary coil 7 and the high voltage coil 3-2
Since the coupling with the lens can be further strengthened, arbitrary focus tracking characteristics can be given to FIG. 8 as in the embodiment, and the degree of freedom in design can be increased.

In each of the above embodiments, one end of the auxiliary coil 7 is connected to the cathode side of the diode 4-1 (
(FIG. 3), the present invention is not limited to this; it can be implemented, for example, it may be connected to the anode side of the diode 4-2.

In this case, it goes without saying that the polarity of the auxiliary coil 7 must be reversed from that shown in FIG.

This is easily understood from the fact that the auxiliary coil 7 has the function of bringing the N point to a potential equivalent to the electrical neutral point of the high voltage coil 3-2 by the voltage induced therein.

As a result, the number of windings required for the auxiliary coil 7 can be changed depending on whether one end of the auxiliary coil 7 is connected to the cathode side of the diode 4-1 or the anode side of the diode 4-2. This can be expected to have the effect of providing a new degree of freedom in the design of the entire high-voltage coil.

As explained above, according to the present invention, a simple structure in which an auxiliary coil for medium voltage output is provided on a bobbin for winding a high voltage coil can eliminate the need for an expensive bleeder resistor that requires a high withstand voltage to extract medium voltage. without the need to use
Furthermore, since a directly smoothed DC medium voltage can be obtained from the flyback transformer, there is no need to add an extra smoothing capacitor, eliminating all the drawbacks of the conventional technology and allowing for significant cost reductions. This has the effect that reliability can be expected to be improved.

Furthermore, according to the present invention, by using the medium voltage obtained from the auxiliary coil for DC medium voltage output as the focus voltage of the cathode ray tube, it is possible to provide optimal focus tracking characteristics for the operation of the cathode ray tube. It is possible to obtain the effect that the characteristics of the machine etc. can be further improved.

[Brief explanation of the drawing]

Figures 1 and 2 are circuit diagrams of a conventional flyback transformer, Figure 3 is a circuit diagram of a flyback transformer according to the basic configuration of the present invention, Figure 4 is a waveform diagram for explaining its operation, and Figure 5 6 is a perspective view and a partial sectional view showing a conventional example of a high voltage coil assembly for a flyback transformer using a diode multi-segmented high voltage coil type, and FIG. 7 is a high voltage coil assembly according to an embodiment of the present invention. 8 is a partially enlarged sectional view of a high voltage coil assembly according to another embodiment, and FIG. 9 is a front view and a side view showing an embodiment of the spacer in the embodiment of FIG. 8. , FIG. 10 is a partially enlarged sectional view of a high voltage coil assembly according to still another embodiment. 1...Core, 2...Low voltage coil, 3-
1.3-2.3-3... High voltage coil, 4-1.
4-2.4-3... Rectifier diode, 5-4
．． 5-5...Resistance for voltage division, 7...
Auxiliary coil for DC medium voltage output, high voltage coil bobbin, 9-1 to 9-9... Winding groove.

Claims (4)

[Scope of utility model registration request] (1) A high-voltage coil that is divided into a plurality of groups, and at least one of the plurality of groups is divided and wound into a plurality of sections, and a high-voltage coil that is located between the group of high-voltage coils and In a diode multi-segmented high voltage coil type flyback transformer comprising at least one high voltage rectifying diode connected in series between two high voltage coils, the section of the bobbin on which the high voltage coil is wound is formed. A DC medium voltage output coil is provided, which is wound around at least a part of the divided portion, and one of the terminals of which is connected to either the cathode side or the anode side of the high voltage rectifier diode, A flyback transformer characterized in that the flyback transformer is configured so that a smoothed DC medium voltage having an arbitrary voltage value lower than the high voltage from the high voltage coil can be obtained from the other terminal of the voltage output coil. (2) The DC medium voltage output coil is adjacent to the section of the high-voltage coil winding bobbin where the high-voltage coil is wound, and is wound within the section where the high-voltage coil is not wound. A flyback transformer according to claim 1 of the utility model registration claim. (3) The DC medium voltage output coil is separated by a spacer from the high voltage coil wound within any one of the partitioned portions of the high voltage coil winding bobbin around which the high voltage coil is wound. The flyback transformer according to claim 1, which is characterized in that the transformer is wound in a winding manner. (4) A state in which the DC medium voltage output coil is mixed with the high voltage coil wound within one of the sections of the high voltage coil winding bobbin around which the high voltage coil is wound. The flyback transformer according to claim 1 of the utility model registration, characterized in that the transformer is wound with