JPH0845762A - Flyback transformer device - Google Patents

Abstract

PURPOSE:To provide a flyback transformer wherein a ringing waveform is improved and heat generation of a switching element is reduced without being affected by the change of operating frequency. CONSTITUTION:The flyback transformer consists of the following: a second switching element 38 which operates so as to synchronize with a first switching element 23, a deflecting transformer 29 wherein one end is connected with a DC power supply, the other end is connected with the second switching element 38, and pulse voltages are generated on a secondary coil 32, and a third coil 27 which generates pulse voltages by a current flowing through a first coil, 2 of a main transformer 1. One end of the secondary coil 32 of the deflecting transformer 29 is connected with the other end of the third coil 27 of the main transformer 1. The other end of the secondary coil 32 is grounded via a second rectifier diode 35 and a resistor 36.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flyback transformer device used for a television receiver, a display monitor device and the like.

[0002]

2. Description of the Related Art Recently, an increasing number of flyback transformer devices have a control circuit for stabilizing a high voltage output voltage.

The structure of a conventional flyback transformer device will be described below. FIG. 3 is a circuit diagram of a conventional flyback transformer device. FIG. 4 is a circuit diagram of a PWM control unit of a conventional flyback transformer device. 3 and 4, reference numeral 1 denotes a main transformer, which includes a primary coil 2, a core 3, a secondary coil 4, a first rectifying diode 5, a speed-up capacitor 6, a high-voltage detection resistor 7, and a high-voltage output terminal. 8 and a detection voltage terminal 9.

Reference numeral 10 is a differential amplifier, 11 is a PWM controller, and as shown in FIG. 4, an input voltage terminal 12, an output voltage terminal 13, an input terminal 14 for a drive frequency signal pulse Pf,
Comparator IC15, 16, Volume 17, Zener diode 18, NPN transistor 19, PN
It has a P-transistor 20 and terminals 21 and 22.
Reference numeral 23 is a first switching element, 24 is a first + B voltage power supply, 25 is a first damper diode, and 26 is a terminal of the primary coil 2.

The operation of the flyback transformer device configured as described above will be described below. First +
When a current flows from the B voltage power supply 24 through the primary coil 2 during the ON period of the first switching element 23, 1
Energy is stored in the next coil 2. The energy is transferred to the secondary coil 4 during the blanking period when the first switching element 23 is off. The pulsed voltage generated in the secondary coil 4 is rectified by the first rectifying diode 5 and becomes a high voltage output voltage.

The voltage generated across the high voltage detecting resistor 7 and the reference voltage are compared by the differential amplifier 10, and the difference voltage is transmitted to the input voltage terminal 12 of the PWM control section 11 as the input voltage. The PWM control unit 11 has an input terminal 14
Since it operates in synchronism with the drive frequency signal pulse Pf input to, the ratio of the on time and the off time (duty) corresponding to both the change of the drive frequency and the change of the high output voltage of the main transformer 1 is changed. The pulse signal of (ratio) is supplied as an input signal of the first switching element 23 of the primary coil 2.

The ON time of the PWM rectangular wave pulse at the output voltage terminal 13 changes depending on the voltage at the detection voltage terminal 9.
For example, when the voltage of the detection voltage terminal 9 decreases, the input voltage of the input voltage terminal 12 decreases, and the voltage of the terminal 22 decreases due to the detection circuit including the NPN transistor 19 and the PNP transistor 20 and the Zener diode 18. The drive frequency signal pulse Pf applied to the input terminal 14 is input to the comparator IC 15, and a triangular wave signal synchronized with this signal is output from the terminal 21.

Further, the triangular wave signal at the terminal 21 and the voltage at the terminal 22 are input to another comparator IC16,
A PWM rectangular wave pulse is generated at the output voltage terminal 13 on the output side. The PWM rectangular wave pulse is synchronized with the drive frequency signal pulse Pf input to the input terminal 14, and when the voltage of the detection voltage terminal 9 is low, the ON time of the duty ratio of the first switching element 23 becomes long. Controlled. When the ON time of the first switching element 23 becomes long, the current of the primary coil 2 of the main transformer 1 increases and the output voltage flowing through the secondary coil 4 rises and is stabilized.
When the output voltage is high, the operation is reversed, the ON time of the first switching element 23 is shortened, and the high voltage output voltage is lowered and stabilized.

Next, a case where the frequency of the drive frequency signal pulse Pf changes will be described. For example, when the cycle of the drive frequency signal pulse Pf becomes longer, the cycle of the triangular wave signal also becomes longer, and the maximum value of this triangular wave signal also becomes higher. Therefore, the period in which the triangular wave signal exceeds the voltage of the terminal 22 becomes long, and the output terminal voltage 1 of the comparator IC 16 becomes 1
The ON time of the PWM rectangular wave pulse output to 3 also becomes long. In this case, the OFF time of the PWM rectangular wave pulse also becomes somewhat longer, but the ON time becomes longer than that rate, so the duty ratio changes. Even when the period of the drive frequency signal pulse Pf is increased as described above, if the voltage of the terminal 22 is lowered by the detection circuit, PW
The ON time of the M rectangular wave pulse becomes long.

[0010]

As described above, in the above-described conventional configuration, the ON time of the first switching element 23 is set so that the maximum peak value of the collector pulse voltage at the terminal 26 of the primary coil 2 becomes constant. It is controlled and the output voltage of the secondary coil 4 rises and is stabilized, but when the operating frequency changes, 1
At the terminal 26 of the next coil 2, a ringing waveform is generated in the voltage waveform of the collector pulse voltage as shown in FIG. 5, and the duty ratio is affected even at the position of H ₁ where the ringing waveform is high. Since the ON operation is performed, heat generation of the first switching element 23 due to the current is large.

The present invention solves the above problems.
An object of the present invention is to provide a flyback transformer device in which the ringing waveform is improved and the heat generation of a switching element is reduced without being affected by a change in operating frequency.

[0012]

To achieve this object, a flyback transformer device of the present invention connects a second switching element that operates in synchronization with the first switching element and one end to a DC power source. A deflection transformer for connecting the other end to the second switching element to generate a pulse voltage in the secondary coil and a tertiary coil for generating a pulse voltage by the current flowing through the primary coil of the main transformer are provided, and the deflection transformer is provided. One end of the secondary coil is connected to the other end of the tertiary coil of the main transformer, and the other end of the secondary coil is grounded via a second rectifier diode and a resistor. .

[0013]

According to the present invention, the second switching element which operates in synchronization with the first switching element, and one end of which is connected to the DC power supply and the other end of which is connected to the second switching element, are pulsed to the secondary coil. A deflection transformer that generates a voltage and a tertiary coil that generates a pulse voltage by the current flowing through the primary coil of the main transformer are provided, and one end of the secondary coil of the deflection transformer is connected to the other end of the tertiary coil of the main transformer. Since the second coil is connected and the other end of the secondary side coil is grounded via the second rectifying diode and the resistor, the voltage waveforms of the collector pulse voltages generated in the respective coils are combined to create the ringing waveform. Since energy is consumed by the resistance, heat generation of the switching element can be reduced.

[0014]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram of a flyback transformer device according to an embodiment of the present invention. In FIG. 1, the same reference numerals as those in the conventional example are basically the same, and thus the description thereof is omitted. In FIG. 1, 1 is a main transformer,
The secondary coil 2, the core 3, the secondary coil 4, the first rectifying diode 5, the speed-up capacitor 6, the high-voltage detection resistor 7, the high-voltage output terminal 8, the detection voltage terminal 9, the tertiary coil 27, and the terminal 28. I have it. 10 is a differential amplifier, 1
1 is a PWM control unit, 14 is an input terminal for driving frequency signal pulse Pf, 23 is a first switching element, and 24 is a first
+ B voltage power supply, 25 is the first damper diode, 2
Reference numeral 6 is a terminal of the primary coil 2.

Reference numeral 29 is a deflection transformer, which comprises a primary coil 30, a core 31, a secondary coil 32, a terminal 33, and a terminal 34. 35 is a second rectifier diode, 36
Is a resistor, 37 is a second + B voltage power supply, 38 is a second switching element, 39 is a second damper diode, 40
Is a resonance capacitor, 41 is a deflection coil, and 42 is an S-shaped capacitor.

The operation of the flyback transformer device configured as described above will be described below. Figure 2
(A)-(d) is a voltage waveform diagram of each part of the flyback transformer apparatus in one Example of this invention. Regarding the operation, the description of the same basic operation as that of the above-described conventional technique will be omitted. The energy stored in the primary coil 2 of the main transformer 1 is P from the PMW control unit 11 synchronized with the drive frequency signal pulse Pf input from the input terminal 14.
By the input signal of the WM rectangular wave pulse, it is transmitted to the secondary coil 4 during the blanking period when the first switching element 23 is off, and is also transmitted to the tertiary coil 27 at the same time. The voltage waveform of the collector pulse voltage transmitted to the tertiary coil 27 has a waveform as shown in FIG. 2 (a) at the terminal 28, which has a _peak value V _CPF and a width P _WF of the positive pulse collector pulse voltage. Have Then, the peak value V of the collector pulse
_A ringing waveform is generated between the _CPFs due to the influence of the secondary coil 4.

Also, synchronized with the first switching element 23.
Drive frequency signal pulse P input to the input terminal 14
The ON period of the second switching element 38 depending on f
From the second + B voltage power supply 37 to the deflection transformer 29 1
The current flowing through the secondary coil 30 causes the deflection coil to move.
Energy is stored in the primary coil 30 of the sensor 29,
This energy turns off the second switching element 38.
Transmission to the secondary coil 32 of the deflection transformer 29 during the blanking period
Is done. It is transmitted to the secondary coil 32 of the deflection transformer 29.
The voltage waveform of the collector pulse voltage generated at the terminal 33
The waveform is as shown in Fig. 2 (b), which is a negative pulse.
Peak value V of collector pulse voltage of_CPH And width P _WHHave
There is. However, this waveform has a waveform as shown in Fig. 2 (a).
There is no ringing waveform. This is the deflection transformer 2
In 9, the high voltage is generated by the secondary coil 4.
Because there is no.

A terminal 28 for a positive pulse voltage waveform including a ringing waveform generated from the tertiary coil 27,
When the terminal 33 of the voltage waveform of the negative pulse that does not include the ringing waveform generated from the secondary coil 32 of the deflection transformer 29 is connected in series, the voltage waveforms of the generated collector pulses are combined, and 2 of the deflection transformer 29 is combined. At the terminal 34 at the other end of the secondary coil 32, a voltage waveform having only a ringing waveform as shown in FIG. 2C is obtained. further,
The terminal 34 of the secondary coil 32 of the deflection transformer 29 is connected to the second
If the second rectifier diode 35 rectifies the ringing waveform generated at the terminal 34 by grounding it through the rectifier diode 35 and the resistor 36, the resistor 36 consumes the energy of the ringing component, so that the ringing waveform is suppressed. It is what is done.

At this time, each collector pulse voltage
The relationship between the peak value and the width is V_CPF ≤V _CPH , And P_WF≤
P_WHOf the tertiary coil 27 and the deflection transformer 29
The secondary coil 32 is formed. That
Is the voltage waveform of the positive pulse, the second rectifier diode 35
If there is a residual positive pulse in the combined voltage because it flows,
It remains without being rectified, but V_CPF ≤V_CPH ,as well as,
P_WF≤P_WHWhen set to, each of the voltage waveform of the terminal 34
V of the voltage waveform of the remaining negative pulse_CPH , And P_WHIs the second
This is because it is rectified by the rectifying diode 35.

As described above, when the ringing waveform of the terminal 34 is suppressed by the second rectifying diode 35 and the resistor 36, the tertiary coil 27 is controlled by the core 3 so that the primary coil 1 of the primary transformer 1 is not connected.
Since it is coupled to the secondary coil 2, this coupling suppresses the generation of the ringing waveform at the terminal 26 of the primary coil 2 of the main transformer 1, and the collector pulse voltage without the ringing waveform as shown in FIG. The voltage waveform is obtained.

[0021]

As described above, according to the present invention, the second switching element which operates in synchronization with the first switching element, one end of which is connected to the DC power supply and the other end of which is connected to the second switching element. A deflection transformer for generating a pulse voltage in the secondary coil and a tertiary coil for generating a pulse voltage by the current flowing through the primary coil of the main transformer are provided, and one end of the secondary coil of the deflection transformer is connected to the main transformer. Since it is connected to the other end of the secondary coil and the other end of the secondary coil is grounded via the second rectifier diode and the resistor, the voltage waveform of the collector pulse voltage is synthesized and the energy of the ringing waveform is consumed. Therefore, it is possible to realize an excellent flyback transformer capable of reducing the heat generation of the switching element without being affected by the change of the operating frequency.

[Brief description of drawings]

FIG. 1 is a circuit diagram of a flyback transformer device according to an embodiment of the present invention.

2 (a) to 2 (d) are voltage waveform diagrams of respective parts of the flyback transformer device according to an embodiment of the present invention.

FIG. 3 is a circuit diagram of a conventional flyback transformer device.

FIG. 4 is a circuit diagram of a PWM control unit of a conventional flyback transformer device.

FIG. 5 is a waveform diagram showing a signal waveform of a primary coil of a conventional flyback transformer device.

[Explanation of symbols]

 1 main transformer 2 primary coil 3,31 core 4 secondary coil 5 first rectifier diode 6 speed-up capacitor 7 high-voltage detection resistor 8 high-voltage output terminal 9 detection voltage terminal 10 differential amplifier 11 PWM control unit 14 input Terminal 23 First switching element 24 First + B voltage power supply 25 First damper diode 26, 28, 33, 34 Terminal 27 Third coil 29 Deflection transformer 30 Primary coil 32 Secondary coil 35 Second rectification Diode 36 Resistance 37 Second + B voltage power supply 38 Second switching element 39 Second damper diode 40 Resonance condenser 41 Deflection coil 42 S-shaped condenser

Claims (1)

[Claims] 1. A main transformer having a primary coil having a DC power supply connected to one end and a first switching element connected to the other end and a secondary coil for generating a high voltage power supply; 1st for obtaining DC high voltage from pulse voltage
Rectifying diode, detecting means for detecting a DC high voltage thereof, and a PWM control unit for changing the ratio of the on time and the off time of a rectangular wave pulse having a frequency determined by an externally applied basic signal by the detected voltage. And a second switching element that operates in synchronization with the first switching element, one end of which is connected to a DC power supply and the other end of which is connected to the second switching element. A deflection transformer for generating a pulse voltage in the secondary coil and a tertiary coil for generating a pulse voltage by the current flowing through the primary coil of the main transformer are provided, and one end of the secondary coil of the deflection transformer is connected to the secondary coil. It should be connected to the other end of the tertiary coil of the main transformer, and the other end of the secondary coil should be grounded via a second rectifying diode and a resistor. A flyback transformer device comprising a.