JPH07163143A - Power supply - Google Patents

Abstract

PURPOSE:To save power consumption while suppressing the oscillation noise by reducing the switching loss of a switching transistor at a blocking oscillation section under light load when a stand-by signal is fed. CONSTITUTION:The power supply comprises an output control section 13 forming a bypath for the base input of a switching transistor Q1 at a blocking oscillation section 6 upon receiving a control signal for oscillation stop command, and a switch circuit section 8 inserted between a section-7 for rectifying and smoothing the output from the output winding 3c of a converter transformer 3 and a load in order to interrupt power supply to the load upon receiving a stand-by signal. The power supply further comprises a first oscillation stop command section 15 for delivering a control signal to the output control section 13 when the output voltage from the rectifying section 7 exceeds a reference level, and a second oscillation stop command section 16 for delivering a control signal to the output control section 13 when the switch circuit section 8 is turned OFF by the stand-by signal and driving the oscillation section 6 at a period set on the outside of audible range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device formed by a switching power supply having a blocking oscillator circuit configuration.

[0002]

2. Description of the Related Art Conventionally, a power supply unit of this type having a blocking oscillator circuit used in a power supply section of a television receiver is constructed as shown in FIG. 4, and the DC power supply of the DC input terminals 1 and 2 is the converter transformer 3. It is supplied to the series circuit of the input winding 3a having the number of turns N1 on the primary side and the switching transistor Q1.

When the power is turned on, a base current is supplied from the DC input terminal 1 to the transistor Q1 via the resistors R1 and R2 of the starting circuit 4 and the base resistor R3 of the drive circuit 5, and the transistor Q1 starts oscillating.

Then, the feedback output of the rectangular waveform of the feedback winding 3b having the number of turns N2 on the primary side of the transformer 3 is the capacitor C1,
Positive feedback is provided to the base of the transistor Q1 via the parallel feedback path of the series circuit of the resistor R4 and the diode D1 and the resistor R3, the transistor Q1 continues to oscillate, and the windings 3a, 3
The blocking oscillator 6 formed by b, the transistor Q1, and the circuits 4 and 5 operates.

Further, the output for load feeding generated in the output winding 3c of the winding N3 on the secondary side of the transformer 3 by the operation of the blocking oscillator 6 is a diode D of the rectifier 7.
2, rectified and smoothed by the smoothing capacitor C2, and converted into direct current.

The DC output of the rectifying section 7 is fed to the load of each section in the receiver via the power supply switch section 8 and the main output terminal 9, and the control circuit of the microcomputer configuration in the receiver is supplied from the microcomputer output terminal 10. Power is also supplied to the department. By this power supply, the control circuit section in the receiver executes various controls such as remote control reception processing, reception channel selection control, and volume control.

Next, the output voltage of the rectifier 7 is divided by the series circuit of the resistor R5, the variable resistor VR, and the resistor R6 of the oscillation stop command unit 11 and monitored. When the output voltage rises and becomes equal to or higher than the reference voltage, The voltage of the sliding piece of the variable resistance VR is the resistance R
7, the on-voltage of the transistor Q2 set by the Zener diode D3 is exceeded, and this transistor Q2 is turned on to cause the resistor R8 and the light emitting diode D of the photocoupler 12.
4, a series circuit of the transistor Q2 and the Zener diode D3 is energized, the diode D4 emits light, and a control signal of an oscillation stop command is formed.

This control signal is received by the phototransistor Q3 of the photocoupler 12 provided in the output control section 13 on the primary side of the transformer 3, converted into an electric signal, current-amplified by the transistor Q4, and the control transistor Q5.
Supplied to the base of. A sawtooth voltage obtained by integrating the rectangular wave voltage of the feedback winding 3b by the resistor R9 and the capacitor C3 is applied to the base of the transistor Q5, and the voltage of the base rises and turns on due to the superposition of the control signal of the oscillation stop command. .

When this is turned on, the transistor Q1
A bypass path for the base input of
1 is forcibly turned off, the output of the output winding 3c is reduced, and the output voltage of the rectifier 7 is reduced and corrected.

When the output voltage falls below the reference voltage, the control signal of the oscillation stop command turns off, the transistor Q5 turns off, the transistor Q1 oscillates again, and the output voltage of the rectifying section 7 is corrected to rise. .

Next, when the power of the receiver is turned off by remote control control or the like, the control circuit section of the receiver shifts from the normal mode to the standby mode to generate a high-level or open-level standby signal. . This signal causes the standby terminal 14 to invert from a low level (earth level) to a high level, and this high level signal is supplied to the base of the transistor Q6 of the power feeding switch circuit unit 8 via the base resistor R10, and this transistor Q6 is When turned off, the load power supply to the main output terminal 9 is cut off.

In FIG. 4, R11 and C4 are resistors and capacitors for filters which are provided in series between both ends of the input winding 3a, D5 is a rectifying diode arranged in parallel with the resistor R2, and R12 and R13. , R14 is a transistor Q
Bias resistance between the base and emitter of Q4, Q5 and Q6.

D6 and R15 are a diode and a resistor that are provided in series between one end of the winding end of the feedback winding 3b and the base of the transistor Q5, and form a discharge path of the capacitor C3. D7 and R16 are a Zener diode and a resistor connected in series, and are a diode D6 and a resistor R1.
5 are arranged in parallel in the series circuit to prevent an overcurrent when the power supply voltage becomes high. C5 is a filter capacitor arranged in parallel with the diode D2.

Further, the mark .circle-solid. In the figure indicates the winding start ends of the windings 3a to 3c. In addition, the transformer 3 and the photocoupler 12 electrically isolate the primary side and the secondary side of the transformer 3 from each other.

[0015]

In the conventional device shown in FIG. 4, the blocking oscillator 6 is constantly oscillated and driven even in the standby mode in which the switch circuit 8 is turned off by the standby signal and the load power supply is cut off. It

At this time, the load of the power supply device is only the control circuit portion that consumes less power, and the load is extremely light. Therefore, the amount of energy transferred from the input winding 3a to the output winding 3c decreases, and the transistor Q1 The oscillation frequency of becomes high.

The switching loss of the transistor Q1 is generated by turning it on and off. In particular, the loss at the time of turning on is constant depending on the circuit and is not influenced by the oscillation frequency. Therefore, when the oscillation frequency becomes high, the switching loss per unit time is increased. Will increase. Further, due to the increase in the switching loss, the heat generation amount of the transistor Q1 increases, and the power consumption increases.

Therefore, there is a problem that power consumption increases in the light load state of the standby mode. Further, when the power supply amount on the primary side becomes larger than the power consumption amount on the secondary side of the transformer 3, the transistor Q1 causes intermittent oscillation,
At this time, several hundred to several K based on conditions such as the oscillation stop period.
There is also a problem that an offensive oscillating sound with an audible frequency of Hz is generated.

In the case of FIG. 4, the control circuit section of the receiver continues to be supplied with power even in the standby mode, but even if the power supply is completely cut off in the standby mode, Similar problems arise. The present invention is
An object of the present invention is to reduce switching loss of a switching transistor of a blocking oscillator when a light load state is caused by a standby signal, prevent power consumption, and prevent annoying oscillation noise.

[0020]

To achieve the above object, in a power supply device of the present invention, a switching transistor is connected in series to the input winding of a converter transformer to which a DC power source is fed, and a switching transistor is connected to the base of the transistor. A blocking oscillating unit that positively feeds back the output of the feedback winding of the converter transformer to maintain the oscillation of the switching transistor, and an output control unit that forms a bypass path for the base input of the switching transistor by the input of the control signal of the oscillation stop command, A rectifying unit that rectifies and smoothes the output of the output winding of the converter transformer; a power supply switch circuit unit that is provided between the rectifying unit and the load and that turns off by the input of a standby signal to cut off load power supply;

When the output voltage of the rectifying section becomes equal to or higher than the reference voltage, a first oscillation stop command section that generates a control signal for an oscillation stop command and supplies it to the output control section, and a power supply switch circuit section is turned off by a standby signal. A control signal of an oscillation stop command is generated at the charge / discharge cycle of the time constant circuit based on the output of the rectifying section and supplied to the output control section, and the blocking oscillator is intermittently driven at a set cycle outside the audible range. And an oscillation stop command section.

[0022]

In the power supply device of the present invention configured as described above, when the power supply switch circuit section is turned off by the standby signal to enter the light load state, the second oscillation stop command section causes
A control signal of an oscillation stop command is formed in the charge / discharge cycle of the time constant circuit and is supplied to the output control unit.

Then, the output control section intermittently forms a bypass path for the base input of the switching transistor of the blocking oscillation section by the control signal of the oscillation stop command, and this transistor oscillates intermittently.

Therefore, when a light load state occurs due to the supply of the standby signal, the blocking oscillator is driven intermittently in a cycle outside the audible range due to the strong intermittent oscillation of the switching transistor, and the switching loss of the switching transistor increases. Is prevented, heat generation of this transistor is reduced, and power consumption is prevented. Moreover, since the blocking oscillator is driven intermittently at a frequency outside the audible range, no annoying oscillation sound is generated.

[0025]

Embodiments (1 embodiment) One embodiment will be described with reference to FIGS. In FIG. 1, the same symbols as those in FIG. 4 indicate the same elements, and the different points are the following points (i) to (iii). (i) In place of the command unit 11 of FIG. 4, a first oscillation stop command unit 15 having the same configuration as the command unit 11 is provided. (ii) Backflow prevention diode D8 at the standby terminal 14
The point where the resistor R10 of the power feeding switch circuit unit 8 is connected via the. (iii) The second oscillation stop command unit 16 is provided.

The command unit 16 is the photocoupler 1
A transistor Q7 forming a second conduction path of the second diode D4, a transistor Q8 for controlling the base of the transistor Q7, a zener diode D9, a resistor R17,
It has R18 and a time constant circuit described below. In this time constant circuit, the output of the rectifying unit 7 is supplied via the resistors R14 and R10 of the power feeding switch circuit unit 8 to resistors R19 and R10.
20 and a capacitor C6.

Then, in the normal mode in which the standby signal of the high level or the open level is not supplied to the standby terminal 14, the standby terminal 14 is held at the low level, the diode D8 is turned on, and the transistor Q6 is turned on.

At this time, the emitter of the transistor Q6,
The output of the rectifier 7 flowing through the resistor R14 between the bases is the resistor R
The capacitor C6 of the command unit 16 is not charged through the diode 10, the diode D8, and the standby terminal 14, the transistor Q8 is turned off, and the transistor Q7 is also held off.
Therefore, in the normal mode, the command unit 16 is in a disconnected state and operates in the same manner as the conventional device of FIG.

Next, as shown in FIG. 2, at t1, the standby terminal 14 is supplied with the high-level standby signal shown in FIG. 3A, and when the normal mode period Tα shifts to the standby mode period Tβ, the rectification unit 7 outputs the resistances R19 and R2 of the command unit 11 via the resistances R14 and R10.
0, the capacitor C6 is supplied to the time constant circuit, the capacitor C6 is charged, and the voltage between its terminals rises as shown in FIG.

When the voltage between the terminals exceeds the threshold voltage Vsat of the transistor Q8 determined by the Zener voltage of the diode D9 at t2, the transistor Q8 is turned on, and its collector, as shown in FIG. The emitter-to-emitter voltage becomes zero. At this time, the transistor Q7 is turned on, the resistor R8, the diode D4 of the photocoupler 12,
A current flows through the transistor Q7, the diode D4 emits light, and a control signal of an oscillation stop command similar to that when the transistor Q2 is turned on is formed.

This control signal is sent to the photocoupler 12
Is received by the transistor Q3 and converted into an electric signal,
This signal turns on the transistor Q5 and turns off the transistor Q1, stops its oscillation, and turns off the transistor Q1.
The voltage between the collector and the emitter becomes 0 as shown in FIG.

When this oscillation is stopped, the output of the output winding 3c disappears, the capacitor C2 of the rectifying section 7 discharges, and the voltage across its terminals decreases as shown in FIG. 2 (b). As a result, the voltage across the terminals of the capacitor C6 also drops. When this terminal voltage drops to the threshold voltage Vsat at t3, the transistor Q8 turns off and the transistor Q7.
Is turned off, the light emission of the diode D4 is stopped, and the control signal of the oscillation stop command is turned off.

When the control signal is turned off, the transistor Q
5 is turned off, the transistor Q1 oscillates again, the output of the output winding 3c rises, and the voltage across the terminals of the capacitor C2 of the rectifying unit 7 and the capacitor C6 of the command unit 16 also rises. Then, when the voltage across the terminals of the capacitor C6 rises again to the threshold voltage Vsat at t4, the oscillation of the transistor Q1 is stopped by the same operation as at t2.

After that, the transistor Q1 repeats the forced intermittent oscillation by repeating the charge and discharge of the capacitor C6. Then, the synchronization of this intermittent oscillation is set to T, the oscillation period of the transistor Q1 during this period is Ton, and the oscillation stop period is Ton.
If they are off, these periods are determined by the on / off cycle of the transistor Q8 based on the time constants of charging / discharging the capacitor C2 and charging / discharging the resistors R19, R20 and the capacitor C6.

On the other hand, the voltage across the terminals of the capacitor C6 changes in a constant width centered on the threshold voltage Vsat due to the repeated charging and discharging described above. The base is reverse biased and turns off. As in the conventional device, the power supply switch circuit section 8 cuts off the load power supply when the standby signal is applied, and the power supply device enters the light load state, as in the conventional device.

Accordingly, when the standby signal causes a light load state, the control signal of the oscillation stop command of the command unit 16 forcibly drives the blocking oscillator 16 intermittently. Since the transistor Q1 intermittently stops oscillation by this intermittent driving, an increase in switching loss of the transistor Q1 due to a light load is prevented, heat generation of the transistor Q1 is reduced, and power consumption is prevented.

Also, based on the settings of the capacitances of the capacitors C2 and C6 and the resistance values of the resistors R19 and R20, the oscillation stop period Toff is set so that the period T becomes a long period outside the audible range.
Is set to be long, and the generation of conventional harsh oscillation noise is also prevented.

(Other Embodiments) Next, other embodiments will be described with reference to FIG. FIG. 3 shows a configuration in which the converter transformer has a plurality of output windings. In FIG. 3, the same reference numerals as those in FIG. 1 designate the same or corresponding components.

The structure of FIG. 3 differs from that of FIG.
The following points (a) to (e). (A) Instead of the transformer 3 shown in FIG. 1, the input winding 17a having the number of turns N1, the feedback winding 17b having the number of turns N2, and the numbers of turns N3 and N
A converter transformer 17 having three output windings 17c, 17d, and 17e of 4 and N5 is provided.

(A) Instead of the rectifying unit 7 of FIG. 1, diodes D2a, D2b, D corresponding to the diode D2, capacitors C2, C5 of FIG. 1 are provided for each of the output windings 17c to 17e.
2c, capacitors C2a, C2b, C2c, C5a, C
The point which provided the rectification | straightening part 18 which has 5b and C5c. (C) Instead of the output terminal 9 of FIG. 1, a high-voltage output terminal 19 for horizontal deflection voltage power supply, a first main output terminal 20a for various signal system power supply, and a second main output terminal for vertical deflection voltage power supply. The point where 20b is provided.

(D) Instead of the switch circuit section 8 of FIG. 1, between the rectifying section 18 and the output terminals 20a and 20b, transistors Q6a, Q6b and resistor R10a corresponding to the transistor Q6, resistors R10 and R14 of FIG. 1, respectively. , R1
0b, R14a, the point provided with the power supply switch circuit unit 21 provided R14b. (E) Instead of the diode D8 of FIG. 1, diodes D8a and D8b are provided between the standby terminal 14 and the resistors R19a and 19b, respectively.

In the normal mode, the standby terminal 14 is held at the low level (earth level), the diodes D8a and D8b are turned on, and the transistor Q6 is turned on.
a and Q6b turn on. Further, the outputs of the output windings 17c to 17e based on the oscillation drive of the blocking oscillator 6 are rectified and smoothed by the rectifier 18, respectively, and converted into a DC high voltage output, a signal system output, and a vertical deflection output.

Then, the high voltage output of the rectifying section 18 is directly supplied from the output terminal 19 to the horizontal deflection circuit section of the receiver,
The signal system output is supplied as it is to the control circuit section of the receiver via the output terminal 10, and is also supplied to various processing circuit sections such as video and audio of the receiver via the transistor Q6a of the switch circuit section 21 and the output terminal 20a. The vertical deflection output is supplied to the vertical deflection circuit section of the receiver via the transistor Q6b of the switch circuit section 21 and the output terminal 20b.

Further, the command section 15 monitors the voltage of the high voltage output as the output voltage of the rectifying section 18, and when this voltage rises above the reference voltage, the transistor Q2 is turned on and the diode D4 of the photocoupler 12 emits light. , A transistor Q of the output control unit 13 by forming a control signal of an oscillation stop command.
5 is turned on to stop the oscillation of the transistor Q1.

Then, by controlling the oscillation of the transistor Q1, the output voltage of the rectifying section 18 in the normal mode is held at the set voltage. Next, when the normal mode is shifted to the standby mode and a high level or open level standby signal is applied to the standby terminal 14, the diodes D8a and D8b are turned off.

The signal system output of the rectifying section 18 is the resistance R.
Resistances R19 and R of the command unit 16 via 14a and R10a.
20, the capacitor C6 is supplied to the time constant circuit, and the capacitor C6 is charged.

When the transistor Q8 is turned on by this charging, the transistor Q7 is turned on and the diode D4 of the photocoupler 12 emits light to form a control signal for an oscillation stop command. This control signal turns on the transistor Q5 and the transistor Q1. Oscillation stops. When the signal system output of the rectification unit 18 is reduced due to this stop, the capacitor C6
, The transistor Q8 turns off, the transistor Q5 turns off, and the transistor Q1 oscillates again.

Thereafter, by repeating the same operation, during the standby mode, the blocking oscillator 6 is forcibly driven intermittently as in the case of the first embodiment. The intermittent driving is determined by the ON / OFF cycle of the transistor Q8 based on the time constants of charging / discharging the capacitor C2b and charging / discharging the resistors R19, 20 and the capacitor C6, as in the case of the first embodiment.

Therefore, also in the case of this embodiment, the same effect as that of the first embodiment can be obtained. The switching circuit unit 21
When the transistors Q6a and Q6b are turned off and the signal system output of the rectifying unit 18 and the load power supply of the vertical deflection output are cut off,
Since the operation of the horizontal deflection circuit section due to the signal system output is stopped, the load power supply of the high voltage output of the rectification section 18 is also substantially cut off.

Although both of the above embodiments are applied to the power supply device of the television receiver, it is needless to say that the present invention can be applied to this kind of power supply device having a blocking oscillation circuit configuration of various devices. Further, the specific configuration of each unit is not limited to the embodiment.

[0051]

Since the present invention is configured as described above, it has the following effects. When the power supply switch circuit units 8 and 21 are turned off by the standby signal to be in a light load state, the second oscillation stop command unit 16 generates a control signal of the oscillation stop command at the charge / discharge cycle of the time constant circuit, and the output control unit. 13, the control unit 13 intermittently forms a bypass path for the base input of the switching transistor Q1 of the blocking oscillator 6, and the transistor Q1 oscillates intermittently.

Therefore, the blocking oscillating section 6 is driven intermittently in a cycle outside the audible range due to the forced intermittent oscillation of the switching transistor Q1, and the switching loss of the switching transistor Q1 increases when the standby signal causes a light load state. Can be prevented, heat generation of the transistor Q1 can be reduced, and power consumption can be prevented.

[Brief description of drawings]

FIG. 1 is a connection diagram of an embodiment of a power supply device of the present invention.

FIG. 2 is a waveform diagram of each part of FIG.

FIG. 3 is a connection diagram of another embodiment of the present invention.

FIG. 4 is a connection diagram of a conventional device.

[Explanation of symbols]

 3, 17 converter transformer 3a, 17a input winding 3b, 17b feedback winding 3c, 17c to 17e output winding 7,18 rectifying unit 13 output control unit 15 first oscillation stop command unit 16 second oscillation stop command unit Q1 switching transistor

[Procedure amendment]

[Submission date] February 18, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0024

[Correction method] Change

[Correction content]

Therefore, in the light load state accompanying the supply of the standby signal, the blocking oscillator is driven intermittently in a cycle outside the audible range due to the forced intermittent oscillation of the switching transistor, and the switching loss of the switching transistor increases. The heat generation of this transistor is reduced and power consumption is prevented. Moreover, since the blocking oscillator is driven intermittently at a frequency outside the audible range, no annoying oscillation sound is generated.

[Procedure Amendment 2]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 1

[Correction method] Change

[Correction content]

[Figure 1]

[Procedure 3]

[Document name to be corrected] Drawing

[Name of item to be corrected] Figure 3

[Correction method] Change

[Correction content]

[Figure 3]

[Procedure amendment 4]

[Document name to be corrected] Drawing

[Name of item to be corrected] Fig. 4

[Correction method] Change

[Correction content]

[Figure 4]

Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI Technical display location H02M 3/338 Z 8726-5H H04N 5/63 Z

Claims (1)

[Claims] 1. A switching transistor is connected in series to an input winding of a converter transformer fed with a DC power source, and the output of a feedback winding of the transformer is positively fed back to the base of the transistor to maintain oscillation of the transistor. A blocking oscillating unit, an output control unit that forms a bypass path for the base input of the transistor by inputting a control signal of an oscillation stop command, a rectifying unit that rectifies and smoothes the output of the output winding of the transformer, and the rectifying unit. And a load, and a power supply switch circuit unit that is turned off by the input of a standby signal to cut off the load power supply, and generates the control signal when the output voltage of the rectification unit is equal to or higher than a reference voltage and outputs the control signal. A first oscillation stop command section to be supplied to the output control section; A second oscillation stop command section for generating the control signal in a charge / discharge cycle of a time constant circuit based on force and supplying the control signal to the output control section to intermittently drive the blocking oscillation section at a set cycle outside the audible range. A power supply device characterized by being provided.