JPS622846Y2 - - Google Patents

Description

[Detailed explanation of the idea]

This invention relates to a high voltage generator used, for example, as a flyback transformer in a television receiver. In the flyback transformer of a television receiver, a high direct current voltage is generated and derived to be applied to the anode electrode of the picture tube. There are various types of circuits for generating the above-mentioned DC high voltage, but in recent years, the secondary winding (high voltage winding) is divided into multiple parts, and these multiple winding parts are connected to multiple rectifiers. A system in which diodes are connected in series is being considered. Here, the above circuit system will be explained using FIG. Note that FIG. 1 typically shows the case where the secondary winding 13 is divided into four pieces. That is, the secondary winding 13 is divided into four winding parts N ₁₁ from the first to the fourth winding parts N 11 ,
D ₁₁ , D 12 , D ₁₃ , D ₁₄ divided into N ₁₂ , N _{13 ,} N ₁₄ and set in the same polarity direction.
They are connected in series by Note that 12 is a core, 11 is a primary winding (low voltage winding), and _C11 is an external capacitor. The operation of the flyback transformer with the above configuration is explained as follows.
To explain with reference to the signal waveform diagram in the figure, when a horizontal pulse is applied to the primary winding 11, the winding section
N ₁₁ to N ₁₄ each have the wave height value V ₁₁ shown in Fig. 2.
A pulse of V ₁₄ is generated. When this is looked at for each of the ends X ₁ to X ₇ of the winding portions N ₁₁ to N ₁₄ , a pulse with a waveform as shown as P ₁₁ in FIG. 2 appears at point X ₁ in the figure. Further, the pulse generated in the winding N ₁₂ is divided by the distributed capacitances C _a2 and C _a3 shown in FIG. 1, and appears at both ends thereof as pulses with waveforms shown as P ₁₂ and P ₁₃ in FIG. 2. Illustrated as shown
The waveform of the pulse _P12 appearing at _{the two} points X has negative polarity when viewed from the ground. The pulse P ₁₂ at this point X ₂ is superimposed on the pulse P ₁₁ at the point X ₁ in the figure. On the other hand, the remainder of the pulse of peak value V ₁₂ generated at point X _{2 appears as a positive polarity at point X 3 in} the figure. This pulse _P13 is then superimposed on the pulse _P12 . The same applies to the windings N ₁₃ and N ₁₄ below, negative polarity pulses P ₁₄ and P ₁₆ appear at points X ₄ and X ₆ in the figure, respectively, and conversely, positive pulses appear at points X ₅ and X ₇ in the figure. Pulses P ₁₅ and P ₁₇ appear. Since the DC level is turned on at the peak of the pulse, it increases so that the peaks of each pulse are superimposed and becomes an output through the diode _D14 , but since the output terminal 14 generally has a large time constant,
_The pulses appearing at _{the 8} points in Figure In other words, the sum of the pulse voltages appearing at each winding portion _N11 to _N14 becomes the output voltage _V10 . A flyback transformer with such a configuration has the following drawbacks. That is, as mentioned above, the output voltage V ₁₀ is only equivalent to the sum of the voltages V ₁₁ to V ₁₄ of the pulses P ₁₁ to P ₁₄ generated in each winding part N ₁₁ to N ₁₄ , and the output voltage efficiency is poor. That is the point. Therefore, in order to obtain a high output voltage _V10 , it is necessary to increase the number of windings and the number of divisions of the secondary winding 13, which causes the problem of increasing the size of the flyback transformer. This idea was developed to address the above-mentioned circumstances, and is a high voltage generator that has excellent output voltage efficiency and can significantly reduce the number of parts, making it possible to reduce weight, size, and manufacturing costs. The purpose is to provide Hereinafter, one embodiment of this invention will be described in detail with reference to the drawings. In FIG. 3, 21 is a primary winding (low voltage winding), and 22 is a core. 23 is divided into two parts by the secondary winding (high voltage winding), and the winding part
M ₁₁ and M ₁₂ are formed. And winding part M ₁₁
The beginning of the winding is connected to the reference potential end, and the end of the winding is connected to the winding part _M12 through the rectifier diode _D21 in the forward direction.
is connected to the beginning of the winding. The end of the winding portion M ₁₂ is connected to the output end 24 via output rectifier diodes D ₂₂ and D ₂₃ in the forward direction. An external capacitor _{C 21} is connected between the anode of the diode D 21 and the connection midpoint of the diodes D ₂₂ and D ₂₃ .
Further, an external capacitor C ₂₂ is connected between the output terminal 24 and the reference potential terminal. The operation in the above configuration will be explained. First, when a horizontal pulse is applied to the primary winding 21, the winding section
A pulse P ₂₁ having a waveform shown as a peak value V ₂₁ is generated at M ₁₁ from the DC DC level=0. In addition, the winding part M ₁₂ has a wave height value V ₂₂ from the AC level = 0.
A pulse P _2A having a waveform shown as is generated. By the way, since the distributed capacitances C _b2 and C b3 are connected in series between the winding start of this winding portion M ₁₂ , that is, _{the two} points Y shown in the figure, and the winding end, that is, the _{three points} Y,
Pulses P ₂₂ and P ₂₃ having peak values obtained by dividing the pulse P _2A generated in the winding portion M ₁₂ by the respective capacitance values are generated in each of the distributed capacitances C _b2 and C _b3 . That is, if the peak values of the pulses P ₂₂ and P ₂₃ appearing in the distributed capacitances C _b2 and C _b3 are V _b2 and V _b3 , the following equation (1) holds true. V _b2 /V _b3 = C _b3 /C _b2 ...(1) However, V ₂₂ = V _b2 + V _b3 By the way, since the connection midpoint of distributed capacitances C _b2 and C _b3 is grounded, the distribution seen from the ground Capacity C
The pulse P ₂₂ of _b2 has negative polarity, and the pulse P ₂₃ of distributed capacitance C _b3 has positive polarity. Then, each pulse rises so as to be superimposed at its peak, resulting in a state as shown in FIG. That is, the pulse P ₂₁ appears at the Y ₁ point in FIG. 3, and the pulse P ₂₁ and the pulse P ₂₂ appear at the Y ₂ point shown in FIG. 3, superimposed on each other at their peak points. Also illustrated
At point _Y3 , a pulse _P23 appears in a superimposed state. Note that the DC component appearing at the _Y3 point is the same as the DC component V ₂₁ +V _b2 appearing at the _Y2 point. Here, the characteristic operation of this invention will be explained. The voltage V ₂₃ across the capacitor C ₂₁ is only the DC component of the pulse P _2A ≒ V ₂₂ during the first retrace period, but during the scanning period, the voltage V 23 across the capacitor C 21 is the DC component of the pulse P ₂₃ charged in the distributed capacitance C _b3 . flows through the loop of diode D ₂₂ , capacitor C ₂₁ , and winding M ₁₁ , and the capacitor
C charged to ₂₁ . At this time, the potential at _point Y in the diagram becomes a negative value as shown in Figure 4, so the voltage charged to the external capacitor _C21 is the DC component of the pulse _P23 charged to the distributed capacitor _Cb3 and the winding. It becomes the sum of the negative voltages of part _M11 . Therefore, during the next retrace period, a voltage greater than the voltage _V22 of the pulse _P2A of the winding _M12 becomes the voltage across the capacitor _C21 , so the diode
D ₂₂ is not turned on, and the pulse P ₂₁ generated in the winding M ₁₁
A voltage obtained by superimposing the voltage across the external capacitor D ₂₁ is peak-rectified through the diode D ₂₃ and outputted to the output terminal 24 as a DC high voltage. In such a configuration, the DC component of the pulse P ₂₃ at point Y ₃ is stored in the distributed capacitance C _b3 , so there is no need to connect an external capacitor to this point Y ₃ . By the way, the output DC high voltage V ₂₀ can be expressed using the following formula. V ₂₀ =V ₂₁ (2+m ^a )+V ₂₂ (1-1+m ^b /K ₁ +1)
...(2) However, K ₁ =C _b3 /C _b2 . Moreover, m ^a indicates the ratio of S ₁ to S ₂ (see FIG. 3) in the pulse P ₂₁ generated in the winding portion M ₁₁ , and m ^a =S ₂ /S ₁ . Similarly, for m ^b , the pulse P _2A generated in the winding part M ₁₂
It shows the ratio of S ₃ to S ₄ (see Figure 3), m ^b =
S ₄ /S ₃ . Since it can be assumed that m ^a and m ^b ≈0, equation (2) can be expressed as the following equation (3). That is, V ₂₀ ≒2V ₂₁ +V ₂₂ (1-1/K ₁ +1) (3) From this equation (3), in order to increase the output voltage V ₂₀ , K ₁ should be increased. That is, distributed capacitance C _b2 , C
It is sufficient to regulate _b3 so that C _b3 is as large as possible than C _b2 . This embodiment described in detail above has the following effects. Since it is configured to perform voltage doubler rectification, it is possible to obtain an output voltage V ₂₀ that is greater than the sum of the pulse voltages generated in each winding portion M ₁₁ and M ₁₂ , resulting in good voltage efficiency. Therefore, in order to obtain a predetermined output voltage, the number of turns of the secondary winding can be reduced compared to that shown in FIG. For example, in the case of obtaining 24KV as an output voltage, if we compare the one in this example (referred to as A for convenience) and the one shown in Fig. 1 (referred to as A for convenience), we can see that the voltage generated in each winding section is The pulse voltage and the voltage across external capacitor _C21 in A are as shown in the table below. However, in case A of this embodiment, the capacitance values of external capacitors C ₂₁ and C ₂₂ are
360PF and 1000PF, and the number of turns of the winding parts M ₁₁ and M ₁₂ are flat wound 1416 (T) and 538 (T), respectively.
K ₁ =3. In addition, in the case shown in Fig. 1, the number of windings in the winding portions _N11 to _N14 is 850 each in flat winding.
(T).

[Table] By the way, if we define the output voltage efficiency η as the ratio between the output voltage and the voltage sum of the pulses generated in each winding, then the output voltage efficiency _η of this example and the output voltage efficiency of the one shown in FIG. η ₂ is the following formula
It is expressed as (4) and (5). That is, η ₁ =V ₂₁ +V ₂₂ /V ₂₀ ...(4) η ₂ =V ₁₁ +V ₁₂ +V ₁₃ +V ₁₄ /V ₁₀ ...
(5) Substituting the data from the previous table into equations (4) and (5) above, η ₁ = (10.0 + 3.8) / 24≒0.55, η ₂ = (6.0 + 6.0 + 6.0 + 6.0) / 24=1 is obtained. As described above, the flyback transformer of this embodiment has better voltage efficiency than the flyback transformer shown in FIG. Therefore, the number of turns of the secondary winding 23 can be reduced as described above, and thereby the winding area of the secondary winding 23 can be reduced. (The one in this example is 1416 + 538 = 1954
(T), the one shown in Figure 1 is 850 x 4 = 3400 (T)
It is. ) Also, the number of divisions of the secondary winding 23 can be reduced compared to the system shown in FIG.
This allows the number of bobbins for winding the secondary winding to be reduced. Furthermore, the number of diodes can be reduced compared to the system shown in FIG. In this way, according to this embodiment, in order to obtain the same output voltage, the number of windings of the secondary winding can be reduced compared to the conventional flyback transformer, and the number of parts can be reduced, so the flyback Reducing transformer manufacturing costs and downsizing the shape,
Weight reduction can be achieved. Further, since the pressure-doubling rectification is performed within the envelope of the flyback transformer, it has the advantage of not requiring a pack unlike the conventional pack-equipped rectification system. 5a, b, and c are the circuit diagrams shown in FIG. 3 _, and in order to obtain an output voltage V ₂₀ =24KV,
Figure a shows the _relationship between the pulse voltage V ₂₁ generated in _{the winding section M 11 and} the output _voltage efficiency η ₁ . , Figure b shows the relationship between V ₂₁ and the pulse voltage V ₂₂ generated in the winding M ₁₂ , and Figure c shows the relationship between V ₂₁ and the external capacitor.
It shows the relationship between the voltage V ₂₃ across C ₂₁ . Note that in the circuit shown in Figure 3, the external capacitor
The capacitance values of C ₂₁ and C ₂₂ were measured as 360PF and 1000PF, respectively. In addition, in the figure, point Q indicates the data described in the explanation of the effect above. Note that this invention is not limited to the previous embodiment. For example, the number of divisions of the secondary winding 23 is not limited to two. In some cases, the number of divisions may be set to three or more in order to obtain the required output voltage in an optimal state. What is shown in FIG. 6 shows the case where it is divided into three parts. In this case, one end of the external capacitor C ₂₁ is connected to the connection midpoint of the output rectifier diodes D ₃₃ and D ₃₄ , and the other end of the external capacitor C 21 may be connected to the anode of the rectifier diode D ₃₂ , or the rectifier diode is connected as shown by the broken line. _D31
It may be connected to the anode of In this way, the number of divisions of the secondary winding in the high voltage generator of this invention is not limited, but in any case, compared to the conventional system shown in Fig. When trying to obtain the following, the number of windings and the number of divisions of the secondary winding can be reduced. Of course, the number of diodes can also be reduced. Furthermore, it goes without saying that the high voltage generator of this invention is effective only for flyback transformers of television receivers. As described above, according to this invention, it is possible to provide a high voltage generator that has excellent output voltage efficiency and can significantly reduce the number of parts, thereby reducing weight, size, and manufacturing costs.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram showing the circuit configuration of a conventional flyback transformer, Figure 2 is a signal waveform diagram to explain the operation of the circuit shown in Figure 1, and Figure 3 is a high voltage generator according to this invention. A circuit diagram showing an example of
FIG. 4 is a signal waveform diagram for explaining the operation of the circuit shown in FIG. 3, FIG. It is a circuit diagram showing a modification. 23 ... Secondary winding, M ₁₁ , M ₁₂ , M ₁₃ ... Winding section, D ₂₁ , D ₃₁ , D ₃₂ ... Rectifier diode, D ₂₂ ,
D ₂₃ , D ₃₃ , D ₃₄ ... Output rectifier diode, C ₂₁ ...
external capacitor.

Claims (1)

[Scope of utility model registration request] A secondary winding divided into a plurality of winding parts, a plurality of rectifier diodes connected in the same polarity direction between each winding part to connect the plurality of winding parts in series, and the rectifier diodes two output rectifier diodes connected in series so as to have the same polarity as the rectifier diodes on the output side of the secondary winding connected in series; and an external capacitor connected between any one of the anodes.