JPS6184970A - Power source circuit - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is applicable to reception of television broadcasts of different broadcasting formats, display of video signals from computers, etc., in addition to reception of regular television broadcasting. The present invention relates to a power supply circuit suitable for use in a multi-scanning receiver capable of receiving video signals having different horizontal frequencies and horizontal deflection widths.

[Conventional technology]

For example, in an NTSC television signal, an image is formed with a vertical frequency of approximately 60 Hz and a horizontal frequency of approximately 15.75 kHz. On the other hand, in the so-called CCIR method, the vertical frequency is 50)1z.

Furthermore, a conversion device has been proposed that doubles the number of scanning lines through arithmetic processing or the like to improve the quality of the received image. When this device is used, the signal output from this has a vertical frequency of, for example, 6011z and a horizontal frequency of approximately 31.5.
It is set to kHz.

In addition, some so-called high-resolution display computer output signals have a horizontal frequency of about 24 kHz. Furthermore, in so-called high-definition televisions, the horizontal frequency is expected to be approximately 33.75 kHz. .

A multi-scanning receiver has been proposed that allows a single device to receive various signals having different vertical and horizontal frequencies.

By the way, in a conventional television receiver, for example, if the horizontal frequency is changed while keeping the power supply voltage Vcc supplied to the flyback transformer constant, the horizontal deflection amplitude is changed, and the high voltage output from the secondary side of the flyback transformer is changed. If this happens, this high voltage will become numb and the brightness of the screen will change.

Therefore, for example, in Figure 0, a circuit as shown in Figure 8 was proposed, the AC commercial power supply (100) is
1) is connected to the bridge rectifier circuit (102) through
A DC output end of this bridge rectifier circuit (102) is connected to one end of a smoothing capacitor (103), and the other end is grounded. One end of this capacitor (103) connects the primary winding (104a) of an isolation transformer (104) constituting a switching regulator and a switching transistor (105).
).

Furthermore, an oscillator (106), a PWM circuit (107), and a drive circuit (10B) are provided in series, and a capacitor (103) is connected to the power path of these circuits (106) to (10B).
) is connected through a resistor (109). The output terminal of this drive circuit (108) is the transistor (10
5). In addition, a damping diode (110) and a resistor (111) are connected in parallel to the primary winding (104a).
), a capacitor (112) is provided.

Further, a DC voltage of, for example, 150 volts is taken out from the secondary winding (104b) of the transformer (104) through a rectifier circuit (113b). This voltage is the amplifier (114),
The voltage is supplied to the drive circuit (108) through the transformer (115), and control is performed to stabilize this 150 volt voltage. In addition, the rectifier circuit (11
3c).

A low voltage DC voltage of, for example, 8 ports or 15 ports is taken out through (113d).

Further, the output terminal of the rectifier circuit (113b) is connected to switching transistors (116a), (116b) and a resistor (117a) connected in parallel for the series regulator.
).

(117b) and is connected to one end of the winding of the horizontal transformer (118). The other end of this transformer (118) is grounded through a switching transistor (119) which is controlled on and off by a horizontal synchronizing signal. A damper diode (120), a resonant capacitor (121), and a horizontal deflection yoke (122) are provided in parallel with this transistor (119), and a correction coil (123) and an S-shaped correction capacitor ( 124) and a deflection current detection resistor (125). The output end of this resistor (125) is connected to a drive circuit (127) through an amplifier (126), and this drive circuit (12
7), transistors (116a) and (116b
) is controlled.

According to this circuit, a predetermined constant DC voltage is first generated by a switching regulator consisting of a transformer (104), etc., and this constant DC voltage is applied to the transistors (116a),
(116b) - is supplied to the horizontal deflection output circuit through the series regulator, etc., and this deflection current is detected by the resistor (125), and feedback control is performed to the above-mentioned series regulator so that this detected value becomes a predetermined value. is applied so that the horizontal deflection amplitude is controlled to be constant. The high voltage is a separate type, with a rectifier circuit (
113b), for example, by supplying a DC voltage of 150 volts.

However, in this circuit, since the series regulator controls the output voltage by changing the collector loss of the transistors (116a), (116b), the transistors (116a), (116b), the drive circuit (127), and the detection Power loss in the resistor (125) etc. is large. This power loss increases as the horizontal frequency decreases, so that the normal horizontal frequency is about 15.
At 75kHz, the power consumption in the series regulator section reaches its maximum, and as a result, the transistor (105) and drive circuit (105) in the switching regulator section are at their maximum.
B) As the heat generation of components such as the rectifier circuit (113b) increases, these components become larger, and the temperature within the receiver significantly deteriorates, resulting in a significant deterioration of axis stability.

Additionally, because of increased power loss, it is not possible to share the horizontal transformer and the flyback transformer for crystal pressure output, and the configuration becomes complicated, as a similar transformer and converter switching circuit are separately provided for high-voltage output. Ta.

The applicant of the present application previously proposed a power supply circuit called a Y-Z power supply (Japanese Patent Application No. 196509/1982).

[Problem that the invention seeks to solve]

A power supply circuit has been proposed for use in a multi-scanning receiver such as the one described above. However, in this circuit, the power loss is extremely large, so 1! There were problems such as the component parts of the source circuit becoming larger and reliability decreasing.

[Means for solving problems]

The present invention provides a first winding having a controlled winding (12a) connected to the power supply side and a control winding (12b) connected to the load side.
A saturable reactor transformer (12) is provided, a primary winding (13a) is connected in series to the controlled winding (12a), and a secondary winding (13b) is connected to the primary winding (13a).
A plurality of DC constant voltage outputs are obtained from the secondary winding (13b) of the first isolated converter transformer (13) arranged in a positive or depolarizing relationship with A second transformer is connected in parallel to the primary side of the saturation reactor transformer (12) and the first isolation converter transformer (13).
The primary winding (31a) of the isolated converter transformer (31)
) and connect this second isolation converter transformer (3
1) in conjunction with the second saturable reactor transformer (41
), and this second saturable reactor transformer (41
) is controlled according to the horizontal synchronization frequency (46), and the DC output voltage is controlled according to the change in the horizontal synchronization frequency,
This power supply circuit operates so that the horizontal amplitude and high-voltage output of the receiver are substantially constant regardless of changes in the horizontal synchronization frequency.

[Effect]

According to the above circuit, even if the horizontal frequency changes to a low range, the DC voltage for the deflection system is extracted to the lightning with high efficiency, so power consumption is reduced, the components are miniaturized,
Reliability can also be improved.

〔Example〕

In Figure 1, an AC commercial power source (1) is connected to a bridge rectifier circuit (3) through a power supply switch (2), and the DC output end of this bridge rectifier circuit (3) is one end of a smoothing capacitor (4). and the other end is grounded.

This capacitor (one end of (1) is connected to one end of transformer (11)
The switching transistor ( The emitter of this transistor (14) is grounded. Also, the secondary winding (llb) of the transformer (11)
) is grounded, and the other end is connected to the base of the transistor (14) through a capacitor (15) and a resistor (16). A reverse diode (17) is connected between the base and emitter of this transistor (14), and a capacitor (18) is connected between the collector and emitter. Furthermore, one end of the capacitor (4) is connected through a resistor (19) to the midpoint between the capacitor (15) and the resistor (16).

Furthermore, the first winding (13b) on the secondary side of the transformer (13)
) A capacitor (21) is connected between both ends of the winding (13b), one end of this winding (13b) is grounded, and the other end is connected to the rectifier circuit (22
For example, an output of 24 volts DC is led out through a). Also, from the center tap of the winding (13b) to the rectifier circuit (2
For example, an output of 15 volts DC is led out through 2b). This 15 volt output terminal is passed through the amplifier (23) to the control winding (12) of the saturable reactor transformer (12).
b). Further, rectifier circuits (22c) are connected to the second and third windings (13c) and (13d) on the secondary side of the transformer (13), respectively.

For example, output terminals of 12 volts and 6.3 volts of DC are led out through (22d).

Further, one end of the capacitor (4) is connected to the collector of a switching transistor (32) through the primary winding (31a) of a second isolated converter transformer (31), and the emitter of this transistor (32) is grounded. Also, one end of the first winding (31b) on the secondary side of the transformer (31) is connected, and the other end is connected to the capacitor (33) and the coil (
34), transistor (32) through resistor (35)
connected to the base of A reverse diode (36) is connected between the base and emitter of this transistor (32), and a capacitor (37) is connected between the collector and emitter. Furthermore, one end of the capacitor (4) is a resistor (38)
It is connected to the base of the transistor (32) through the transistor (32).

Furthermore, the second winding (31c) on the secondary side of the transformer (31)
) is grounded, the other end is connected to one end of the capacitor (42) through the controlled winding (41a) of the second J saturation reactor transformer (41), and the other end is grounded. One end of this capacitor (42) is a rectifier circuit (43)
connected to. The output end of this rectifier circuit (43) is connected to the collector of a switching transistor (45) through the primary winding (44a) of a flyback transformer (44), and the emitter of this transistor (45) is grounded. Further, a terminal (46) to which a horizontal synchronizing signal is supplied is connected to a horizontal oscillator (47), and the output terminal of this oscillator (47) is connected to a transistor (45) through a drive circuit (48).
) is connected to the base of the A damper diode (49), a resonant capacitor (50), and a horizontal deflection yoke (51) are provided in parallel with this transistor (45), and a correction coil (52),
A three-figure correction capacitor (53) is provided. Also, a high voltage output end is led out from the secondary winding (44b) of the flyback transformer (44).

In this circuit, the output end of the rectifier circuit (43) is passed through the amplifier (54) to the β'' saturation reactor transformer (
41) is connected to the control winding (41b).

Further, the terminal (46) is connected to a frequency-voltage conversion circuit (55), and the output terminal of this conversion circuit (55) is connected to the amplifier (55).
4) is connected to the gain control terminal. In addition, the rectifier circuit (22
The output terminal of b) is connected to the power supply terminal of the amplifier (54).

Therefore, in this circuit, first the winding (llb), the capacitor (15), the resistor (16), the tie-out (17)
) etc., the switching of the transistor (14) is controlled by a self-excited oscillation base drive circuit, which causes the primary winding (13a) of the transformer (13) to change to wJ&! be done.

Note that starting is performed by the resistor (19). For this reason, each 2
Desired voltages are taken out to the next windings (13b) to (13d), respectively, and a voltage output of, for example, 15 volts from these voltages is passed through the amplifier (23) to the control winding (12) of the saturable reactor transformer (12). 12b), thereby controlling the magnetic flux of the transformer (12), controlling the current flowing to the controlled winding (12a), and stabilizing the voltage of each secondary winding (13b) to (13d). be done.

Also winding (31b), capacitor (33), coil (3, 4), resistor (35), diode (36)
The switching of the transistor (32) is controlled by a self-excited oscillation base drive circuit such as the above, and the primary winding (31a) of the transformer (31) is thereby excited.

Note that starting is performed by a resistor (38). Therefore, a predetermined voltage is taken out to the secondary winding (31c), and this voltage is applied to the controlled winding (41c) of the saturable reactor transformer (41).
a) is supplied to the flybank transformer (44) through a rectifier circuit (43) and the like.

At this time, the output voltage of the rectifier circuit (43) passes through the amplifier (54) to the control winding (41b) of the transformer (41).
> is supplied to stabilize the output voltage, and
A voltage corresponding to the horizontal frequency of the input video signal is formed in the frequency-voltage conversion circuit (55), and the gain of the NAMP (54) is controlled by this voltage, so that the above-mentioned flyback transformer (44) ) is controlled according to the horizontal frequency. This makes it possible to always obtain a constant horizontal deflection width and screen brightness.

For example, in a multi-scanning receiver, even if the horizontal frequency of the input video signal varies, in order to keep the screen brightness and horizontal deflection width constant, the frequency must be adjusted as shown in Figure 2. (15,75kHz, AB in the diagram)
Even if the current IP-P ('A.

C) and the fly hack pulse voltage VP (B, D) corresponding to the brightness of the screen need only be constant.

Here, the shape of the flybank pulse is the deflection yaw (51
) and the value of the resonance capacitor (50), so it is always almost constant. Therefore, in the above circuit, IP-P and Vp
In order to completely match the output voltage Vcc of the rectifier circuit (43), the output voltage Vcc of the rectifier circuit (43) may be controlled to be inversely proportional to the value obtained by subtracting the period of the flybank pulse (for example, 6μ5ec constant) from the period at each horizontal frequency.

However, in an actual video signal, the screen display period is proportional to the period at each horizontal frequency, so in order to keep the horizontal deflection width constant during the display period, it is necessary to make the output voltage Vcc proportional to the horizontal frequency. be. However, in this case, the flyback pulse voltage Vp changes in inverse proportion to the horizontal frequency. Therefore, in the above circuit, the output voltage of the frequency-voltage conversion circuit (55) is compared by the wind comparator (56), and the horizontal frequency A correction capacitor (50a) is connected in parallel to the resonance capacitor (50) by controlling the switch circuit (57) according to the range of the correction capacitor (50a).

(50b) is connected.

In the above circuit, the characteristics of the frequency-voltage conversion circuit (55) are as shown in FIG. 3A. As a result, the horizontal oscillation frequency is controlled, and the DC control current of the control winding (41a) of the saturable reactor transformer (41) is controlled as shown in FIG. 3B.

As a result, the voltage Vcc from the rectifier circuit (43) is
controlled as follows. This makes the horizontal deflection width constant. Further, at this time, the power conversion efficiency η is approximately constant as shown by the solid line in the third figure, and is significantly improved compared to the conventional one shown by the broken line.

In this way, it is possible to receive images with a constant horizontal deflection width and screen brightness regardless of changes in the horizontal frequency, but according to the circuit described above, even if the horizontal frequency changes and falls into a low range, Since the direct current voltage for the deflection system is always extracted with high efficiency, power consumption is reduced, component parts are miniaturized, and reliability can be improved. Further, since the flyback pulse voltage is always substantially constant, a high voltage output can be stably obtained using the flybank transformer (44), and there is no need to provide a separate configuration for one voltage output.

By the way, the above-mentioned circuit is complicated because two sets of primary circuits for excitation of the transformer are provided, and the printed circuit board and magnetic shielding case are large. Also, transformer (
31) Since a large excitation current flows through the circuit on the primary side, the problem remains that power loss in the starting resistor (38) becomes large.

Therefore, in Fig. 4, these excitation circuits are used in common to eliminate the above-mentioned problem. In other words, in the figure,
The controlled winding (12) of the saturable reactor transformer (12)
a) and the primary winding (1) of the isolated converter transformer (13)
An isolated converter transformer (3a) is connected in parallel to the series circuit of 3a).
Connect the primary winding (31a) of 1). In addition, the excitation circuit for the transistor (32) to the resistor (38) is omitted, and the other components are configured in the same manner as in FIG. 1.

In this example, the current and voltage waveforms at each part are as shown in FIG. Moreover, FIG. 6 shows an equivalent circuit.

In this example as well, the same effects as described above can be obtained, the circuit configuration is simplified, and the power loss in the starting resistor is reduced. Note that since the power consumption of the above-mentioned circuit is small, the circuit can be shared in this way.

Further, in Fig. 7, the saturable reactor transformer (41
) is provided on the primary side of the transformer (31). In this example as well, the effects are the same as described above.

〔Effect of the invention〕

According to the present invention, even if the horizontal frequency changes and falls into a low range, the DC voltage for the deflection system is always extracted with high efficiency, reducing power consumption, downsizing the components, and improving reliability. can also be improved.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an example of the present invention, FIGS. 2 to 7A are diagrams for explaining the same, and FIG. 8 is a diagram for explaining a conventional device. (12) and (41) are saturable reactor transformers, (13) and C31) are isolated converter transformers, (44) are flyback transformers, (51) are horizontal deflection yokes, and (55) are frequency-voltage conversion circuits. be.

Claims (1)

[Claims] A first saturable reactor transformer is provided having a controlled winding connected to the power supply side and a control winding connected to the load side, the primary winding being connected in series with the controlled winding, and 2
A plurality of DC constant voltage outputs are obtained from the secondary winding of the first insulated converter transformer, the secondary winding of which is arranged in a positive or depolarizing relationship with the primary winding, and the A primary winding of a second isolating converter transformer is connected in parallel with the primary side of the first saturable reactor transformer and the first isolating converter transformer; A saturable reactor transformer is provided, and this second saturable reactor transformer is controlled according to the horizontal synchronization frequency, so that the DC output voltage is controlled according to the change in the horizontal synchronization frequency, and the horizontal amplitude and high voltage output of the receiver are controlled according to the horizontal synchronization frequency. A power supply circuit that operates almost constant regardless of changes in synchronous frequency.