JPS5850458B2 - oscillation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an oscillation device that can obtain an oscillation output synchronized with an AC power supply and whose oscillation phase does not change due to noise superimposed on the AC power supply.

Conventionally, an oscillation device shown in FIG. 1 has been proposed.

1 is an AC power source, and a full-wave rectifier 2 is connected to this power source 1.

A constant voltage element 4 is connected between the output terminals of the rectifier 2 via a resistor 3, and the rectified voltage is made into a constant voltage, that is, a trapezoidal waveform voltage.

A tension oscillation circuit 5 is connected in parallel with this constant voltage element 4.

This constant oscillation circuit 5 includes a voltage dividing circuit of a resistor 6 and a resistor 7, a time constant circuit of a transistor and a capacitor 90,
It consists of a PUTIO whose gate is connected to the voltage dividing point of the voltage dividing circuit and whose anode is connected to the connection point of the transistor 8 and capacitor 9 of the time constant circuit, and a pulse transformer 11 provided at the cathode of this PUTIO. It is.

A control signal is input to the base of the transistor 80 of the time constant circuit, and the degree of conduction is changed to change the time constant of the time constant circuit.

Also, the transistor 8 and capacitor 9 of the time constant circuit
A resistor 12 connected between the connection point and the positive electrode of the rectifier 2
improves the linearity of charging the capacitor 9.

In the conventional device configured in this manner, the voltage at the voltage dividing point of the voltage dividing circuit, that is, the trapezoidal waveform voltage, is applied to the gate of PUTIO, and the voltage across the capacitor 90 of the time constant circuit, which rises with time, is applied to the anode.

When the anode potential of PUTlo reaches a predetermined value relative to the gate potential, PUTlo becomes conductive and the pulse transformer 11 outputs a pulse.

In addition, a trapezoidal waveform voltage is applied to the gate of PUTIO, and this voltage drops to zero potential in synchronization with the half cycle of AC power supply 1, so once it reaches this zero potential, the PU
Tlo is reliably conductive and the charge in the capacitor 9 of the time constant circuit is discharged.

Therefore, since the capacitor 9 starts charging every half cycle of the AC power supply 1, PUTIO conducts at a constant phase of each half cycle of the AC power supply 1, and the pulse transformer 11
It can output pulses from.

However, in this conventional device, if noise is superimposed on the AC power supply 1 or the like, this noise is directly included in the trapezoidal voltage and is applied to the gate of PUTlo.

For this reason, for example, if polar pulse noise that lowers the voltage is superimposed on the AC power supply 1, the gate potential of PUTlo will drop instantaneously due to the noise, so if the capacitor 9 is charged to some extent at this time. ,PUTlo
was conductive.

Therefore, there is a drawback that the pulse transformer 11 outputs a pulse at a phase earlier than a predetermined phase, making it impossible to obtain a pulse output at a predetermined phase.

Note that this drawback can be overcome by connecting a noise bypass capacitor between the gate and cathode of PUTIO, but on the other hand, the trapezoidal waveform voltage applied to the gate will be smoothed, so the AC This made it impossible to obtain a pulse output synchronized with each half cycle of the power supply 1.

The present invention has been made in order to eliminate such drawbacks of conventional devices, and provides an oscillation device that can obtain a pulse output synchronized with an AC power supply and whose pulse output phase does not change due to noise. The purpose is to

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows the first embodiment.

20 is an AC power supply, 21 is a full-wave rectifier, 22 is a resistor, 2
Reference numeral 3 denotes a constant voltage element, which has the same configuration as in FIG.

Next, 24 is a smoothed DC power supply, and a tension oscillation circuit 25 is connected to this power supply 24.

In addition, the tension oscillation circuit 25 includes a voltage dividing circuit including a resistor 26 and a resistor 27 connected to the smoothed DC power supply 24;
A transistor 28 connected in parallel to the constant voltage element 23
and a time constant circuit consisting of a capacitor 29, a PUT 30 whose gate is connected to the voltage dividing point of the voltage dividing circuit and whose anode is connected to the connection point of the transistor 28 and the capacitor 29 of the time constant circuit, and a cathode of this PUT 30. It consists of a pulse transformer 31.

That is, a smoothed DC voltage is applied to the gate of the PUT 30 instead of a trapezoidal voltage.

Further, the resistor 32 is provided between the positive electrode of the full-wave rectifier 21 and the capacitor 29 in order to improve the linearity of charging the capacitor 29.

Next, 33 is a first transistor whose emitter and collector are connected in series with a resistor 34 and connected in parallel to the smoothed DC power supply 24, and a resistor 35 and a resistor whose base is connected in parallel to the constant voltage element 24. It is connected to the intermediate point of 36 series circuits, and conduction is controlled in synchronization with the trapezoidal waveform voltage, that is, the AC power supply 1.

Further, 3T is a second transistor whose emitter and collector are connected in series with the resistor 38 and connected in parallel with the capacitor 29 of the time constant circuit.

The base of the second transistor 37 is connected to the collector of the first transistor 33, and is conductive when the first transistor 33 is non-conductive and non-conductive when the first transistor 33 is conductive.

Therefore, when the second transistor 37 is conductive, the charge in the capacitor 29 of the time constant circuit is changed from the capacitor 29 to the resistor 38 to the second transistor 37.
It is discharged through the closed circuit of capacitor 29.

Note that 39 is the emitter of the first transistor 33.
This is a resistor connected in parallel to the collector.

Further, a control signal is supplied to the base of the transistor 28 of the time constant circuit to change the time constant of the time constant circuit.

Next, the operation will be explained with reference to FIG.

In FIG. 3, A is the voltage of the AC power supply 1, middle is the voltage across the main constant voltage element 240, C is the emitter-collector voltage of the first transistor 33, and 2 is the emitter-collector voltage of the second transistor 37. indicates the voltage of the capacitor 29.

The voltage at the voltage dividing point of the voltage dividing circuit, that is, the smoothed DC voltage is applied to the gate of the PUT 30, and the voltage across the capacitor 290 charged via the transistor 28 or the resistor 32 is applied to the anode.

Then, when the potentials of A, .

On the other hand, a trapezoidal waveform voltage as shown at the beginning of FIG. 3 is applied to the base of the first transistor 330, and as shown in FIG.
The first transistor 33 is conductive, and the first transistor 33 becomes non-conductive when the voltage becomes low enough to make the transistor conductive.

The second transistor 37 is non-conductive when the first transistor 33 is conductive, and conductive when the first transistor 33 is non-conductive, as shown in FIG. When the first transistor 33 becomes non-conductive, that is, when the trapezoidal wave voltage drops to near zero, it becomes conductive and short-circuits the capacitor 29 of the time constant circuit.

Therefore, the charge in the capacitor 29 is accumulated while the second transistor 37 is conducting, as shown in the third diagram.
Discharge occurs through this second transistor 37.

Therefore, the capacitor 29 of the time constant circuit starts charging every half cycle of the AC power supply 1, and PUT is output at a constant phase.
30 can be electrically connected.

Furthermore, even if noise is superimposed on the AC power supply 20, the PUT
Since the divided voltage of the smoothed DC power supply 24 is applied to the gate 30, the gate potential is not adversely affected by noise.

For example, even when the smoothed DC power source 24 is obtained from the AC power source 20, noise can be absorbed by the smoothing capacitor.

Furthermore, by connecting a noise bypass capacitor between the gate and cathode of PUT 30, fluctuations in gate potential due to pulse noise can be prevented.

Of course, it is easy to understand from the above description that in this case as well, a pulse output synchronized with the AC power supply 20 can be obtained.

In this embodiment, if pulse noise is superimposed on the AC power supply 20, this noise will also be included in the trapezoidal waveform voltage.
may momentarily become non-conductive, and during this time the second transistor 37 may become conductive and short-circuit to the capacitor 29.

However, since the second transistor 37 becomes conductive due to the pulse noise as described above, the capacitor 29 is only slightly discharged due to this, so it has almost no effect on the conduction phase of the PUT 30. It is something.

FIG. 4 shows an embodiment applied to a constant voltage device using phase control.

Components that are the same as those in FIG. 2 are given the same reference numerals and explanations will be omitted.

A triac 40 for phase control is provided between the AC power supply 20 and the load 4, such as a light bulb, and its control pole is connected to the output winding of the pulse transformer 31 of the oscillator circuit 25.

46 is a transformer for detecting load voltage, and its primary winding is connected in parallel to the load 41.

Further, the secondary winding is connected to a rectifier 47.

The output of this rectifier 47 is then output from the control signal generator 4.
8 is input.

The control signal generator 48 includes known circuits such as a smoothing circuit 60, a time constant circuit 70, and an error amplifier 80, and compares the detected load voltage with a reference voltage to calculate the voltage between the two sides. This outputs a control signal that reduces the error.

This control signal is input to the base of the transistor 28 of the time constant circuit of the reinforcement oscillation circuit 25, and changes the time constant of the time constant circuit.

Next, the effect will be explained.

The tension oscillation circuit 25 outputs a pulse according to the time constant of the time constant circuit determined by the control signal from the control signal generator 48, and makes the triac 40 conductive.

Therefore, the load 41 is supplied with phase-controlled AC power.

The voltage of this load 41 is detected by a transformer 46 and compared with a reference voltage, thereby controlling the voltage of the load 41 to be constant.

Therefore, in this embodiment, a constant light output can be obtained from the light bulb, which is the load 41.

The oscillation operation in this embodiment is the same as that in the embodiment shown in the second figure, so a description thereof will be omitted.

By the way, in the case where the load 41 is energized by phase-controlled power as in this embodiment, the tension oscillation circuit 25
The load 41 may be rendered inactive by stopping the pulse output of the triac 40 and rendering the triac 40 non-conductive.

For example, when this embodiment is applied to control the light output of a light source used in a copying machine, the smoothing DC power supply 24 is opened to stop the operation of the control signal generator 48, and the transistor 28 of the time constant circuit is The control signal may not be applied.

In this case, in this embodiment, by opening the smoothed DC power supply 24, no voltage is applied to the gate of the PUT 31, and the gate potential becomes zero potential.

Therefore, even if the capacitor 29 of the time constant circuit is to be charged by the output of the rectifier 21 via the resistor 32, the current from the rectifier 21 is The current flows continuously to the PUT 31, and the pulse transformer 31 does not output any pulses.

Therefore, the triac 40 does not conduct undesirably, and no current flows through the load 41.

On the other hand, the conventional device shown in FIG. 1 has the following drawbacks.

That is, in the device shown in FIG. 1, even if the control signal is not supplied to the transistor 8 of the time constant circuit, the PU
Since a trapezoidal voltage is applied to the gate of T9, and the capacitor 9 of the time constant circuit is charged via the resistor 12, PUTIO becomes conductive and outputs a pulse.

Therefore, the triac for phase control becomes conductive, causing current to flow through the load.

For this reason, it has been considered to provide a relay contact in the charging circuit of the capacitor 9 of the time constant circuit, but this has the drawback of being expensive.

FIGS. 5 and 6 show other embodiments.

The same parts as in FIG. 2 are given the same reference numerals.

In FIG. 5, a time constant circuit is connected to a smoothed DC power supply 24, and the conduction of the first transistor 33 is controlled by the full-wave rectified output of the AC power supply 20.

In FIG. 6, a noise bypass capacitor 90 is connected between the gate and cathode of the PUT 30.

Note that the present invention is not limited to the above embodiments.

For example, the smoothed DC power source may be derived from the AC power source or may be a separate power source.

Further, the tension oscillation circuit may include not only the PUT but also the UJT.

As described in detail above, the present invention connects a constant oscillation circuit to a smoothed DC power source, and conducts charging and discharging of a capacitor of a time constant circuit that determines the oscillation phase of the constant oscillation circuit in synchronization with an AC power source. Since the oscillation device is controlled by the first and second transistors that are controlled, it is possible to obtain an oscillation output synchronized with the AC power supply, and the oscillation phase does not change due to noise superimposed on the AC power supply, etc. It is possible to provide

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing a conventional example, Fig. 2 is a circuit diagram showing a first embodiment of the present invention, Fig. 3 is a voltage waveform diagram explaining the operation, and Fig. 4 is also an AC constant voltage device. FIGS. 5 and 6 are circuit diagrams showing other embodiments of the present invention. 20... AC power supply, 24... Smoothing DC power supply, 25... Volcanic oscillation circuit, 33...
- First transistor, 37... Second transistor.

Claims (1)

[Scope of Claims] 1. A smoothed DC power supply, a time constant circuit including a capacitor, and an oscillation circuit connected to the smoothed DC power supply, an AC power supply, and a conduction controlled in synchronization with the AC power supply. First
and a transistor connected in parallel to the capacitor of the above-mentioned oscillation circuit, which conducts when the first transistor is non-conductive and becomes non-conductive when the first transistor conducts, thereby controlling charging and discharging of the capacitor. An oscillation device comprising: a second transistor that causes the above-mentioned oscillation circuit to oscillate in synchronization with the AC power supply. 2. The oscillation device according to claim 1, wherein the smoothed DC power source is obtained by rectifying and smoothing the AC power source. 3. The oscillation device according to claim 1 or 2, wherein the tension oscillation circuit includes a PUT. 4. Claims characterized in that the time constant circuit of the tension oscillation circuit includes a series circuit of a transistor and a capacitor, and the time constant is changed by controlling the transistor with a control signal. The oscillation device according to any one of 1 to 3. 5. The oscillation according to any one of claims 1 to 4, wherein the tension oscillation circuit controls conduction of a semiconductor phase control device that controls power supply to a load by the AC power supply. Device.