JPS62178171A - High-voltage power unit - Google Patents

Abstract

PURPOSE:To stabilize a secondary induced output by constituting an astable- multivibrator of a digital inverter, applying voltage corresponding to supply voltage to the multivibrator and altering oscillation frequency and a duty ratio. CONSTITUTION:A multivibrator 1 is constituted of cascade-connected digital inverters 11-13, resistors 14, 15 connected in series between an output terminal for the inverter 13 and an input terminal for the inverter 11, a capacitor 16 connected between an output terminal for the inverter 12 and a node between the resistors 14, 15, etc. An input terminal and an output terminal for the multivibrator 1 are supplied with input voltage from a sliding terminal for a variable resistor 61. The oscillation frequency and duty ratio of the multivibrator 1 change in response to input voltage, and a secondary induced output from a set-up transformer 3 is stabilized to supply voltage fluctuation.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Valve 'Jr] The present invention relates to a high-voltage power supply device with a simple circuit configuration, small size, and low cost, and relates to a high-voltage power supply device suitable as a high-voltage power supply for a copying machine, for example.

[Prior Art] Conventionally, series dropper type and switching regulator type high voltage power supply devices with stabilized output have been known.

[Problems to be Solved] However, the former method is inefficient and generates a large amount of heat, resulting in an increase in the size of the device. Further, the latter has the disadvantage that the circuit configuration is complicated and expensive.

The present invention has been made in view of the problems in the conventional type described above, and an object of the present invention is to provide a high voltage power supply device with a simple circuit configuration, small size, and low cost.

[Means and operations for solving the problem] In order to achieve the above object, in the first invention, an unstable multivibrator is configured by a digital inverter, and a power supply voltage VB is applied to the input signal side or output of the multivibrator. The oscillation frequency and duty ratio are varied by applying a voltage according to the voltage. With this configuration, the oscillation frequency rises or falls according to the high/low of the power supply voltage v8, and the duty ratio decreases or increases, and the secondary induced output of the step-up transformer driven by this oscillation output is caused by fluctuations in the power supply voltage. stabilized against

In a second invention, in addition to the first invention, a quantity of electricity to be stabilized among the quantity of electricity (voltage, current, power, etc.) supplied to the load via the step-up transformer is further detected, and this detection output is provided. The oscillation frequency and duty ratio are also varied by controlling the operating voltage VCC of the unstable multivibrator. Further, in a third aspect of the invention, the detection output is applied to the unstable multivibrator together with a voltage corresponding to the power supply voltage Va. According to these second and third inventions, the amount of electricity supplied to the load is stabilized not only with respect to high and low power supply voltages Vs but also with respect to fluctuations in the load.

[Description of Example 1 Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 shows the configuration of a high voltage power supply device according to an embodiment of the present invention. In the figure, B is the positive terminal of a DC power source (not shown), and the negative terminal of this DC power source is grounded. 1
is an astable multivibrator, 2 is a transistor, 3 is a stepping transformer, and 4 is a high voltage rectifier circuit.

Multivibrator 1 has cascade-connected digital inverters it, 12.13, and the output end of inverter 13 (
Resistors 14 and 15 are connected in series between the output end of the multivibrator 1 (output end of the multivibrator 1) and the input end of the inverter 11, and the connection point between the output end of the inverter 12 and the input end of the multivibrator 1). It is composed of a capacitor 16 and the like connected between the two, and generates a high frequency output at a frequency higher than the audible frequency, for example, 20 to 100 kHz. This high-frequency output is supplied to the base of the transistor 2 via the resistor 5, and the transistor 2 is turned on and off at high frequency to drive the primary winding 3p of the step-up transformer 3. As a result, a high-voltage, high-frequency voltage is generated in the secondary winding 3S of the step-up transformer 3. The high-voltage rectifier circuit 4 rectifies and smoothes this high-voltage high-frequency voltage, converts it into a high-voltage DC voltage, and supplies it to a load (not shown). Note that here, digital inverters 11.12
．． 13, three of the six inverter circuits included in 0MO3-IC4069 are used.

By the way, if the oscillation frequency and duty ratio of the multivibrator 1 are kept constant, the secondary induced output of the step-up transformer 3 or the output of the high voltage rectifier circuit 4 will be the voltage of the DC power supply (
It is affected by variations in Va (hereinafter referred to as input voltage) and load.

Therefore, in this embodiment, an input voltage compensation circuit 6 is provided, and the input voltage v8 is divided by the variable resistor of this circuit 6.
It is applied to the input signal side and output of the multivibrator 1. That is, both fixed terminals of the variable resistor 61 are connected to the positive and negative terminals of the DC power supply, respectively, and the sliding terminals are connected to the input and output ends of the multivibrator 1 via the diode 62; P3 and the resistor 63, respectively. Connected.

Next, the operation of the apparatus shown in FIG. 1 will be explained.

First, it is assumed that the input voltage Vs has increased from the standard voltage. In this case, the voltage at the sliding terminal of the variable resistor 61 increases and is applied to the input and output ends of the multivibrator 1. As a result, mainly multivibrator 1
The rise of the terminal voltage of the capacitor 16 becomes steeper due to the effect of the voltage applied to the input terminal of the inverter 13, and the rise of the terminal voltage of the capacitor 16 becomes steeper due to the effect of the voltage applied to the output terminal of the multi-vib break 1. If not, then about 1/2 VCC (where ycc is the operating power supply voltage of the inverter 13) increases. Therefore, the oscillation frequency of the multivibrator 1 increases, the duty ratio decreases, and the output of the device decreases.

On the other hand, when the input voltage VB falls below the standard voltage, contrary to the above, the voltage at the oscillating terminal of the variable resistor 61, and therefore the voltage applied to the input and output ends of the multivibrator 1, falls. The rise of the terminal voltage of capacitor 16 becomes more gradual, and the threshold voltage of inverter 13 decreases.

As a result, the excavation frequency of the multivibrator 1 decreases, the duty ratio increases, and the output increases.

In other words, the device shown in Fig. 1 changes the output of the device in a direction that compensates for increases and decreases in the input voltage 8 by controlling the pulse width (PWM) of the output waveform of the multivibrator 1 according to the input voltage. The output is not easily affected by the input voltage. That is, the output is stabilized against fluctuations in the input voltage V8.

FIG. 2 shows a circuit configuration of a high voltage power supply device according to another embodiment of the present invention. The device shown in the figure, in contrast to the device shown in FIG. device 12, capacitor 7
3.Detection circuit 7 consisting of 74J5, diode 75, etc.
6, and by varying the output voltage Vcc of the constant voltage circuit using this detection output, the oscillation frequency and duty ratio of the multivibrator 1 are varied, and the output J current of the step-up transformer 3 is controlled by negative feedback. This is the one in which a circuit 7 is added. Also, here MOS-IC
2 out of 4 2-person NOR circuits included in /1001
Two are used as inverters 12 and 13, one is used as inverter 11, and one input terminal is used as a disable terminal for stopping oscillation. That is, in the multivibrator 1, this disable terminal is 11 L I
Oscillation starts and continues while it is at T level, but when it is at HI
Oscillation stops when the + level is reached.

In the device shown in FIG. 2, when the input voltage Vs changes, output fluctuations due to the input voltage are suppressed in the same manner as in the device shown in FIG.

Also, if the output current changes due to load fluctuations,
The detection output voltage of the detection circuit 76 changes.

This voltage is applied to the base of the output voltage CC detection transistor 77 of the constant voltage circuit 71, and the transistor 17 detects the output voltage of the constant voltage circuit 71 even when the detected output voltage fluctuates. It operates similarly to change the base drive current of transistor 78. As a result, the output voltage of the constant voltage circuit 71, that is, the operating voltage ycc of the inverter 13 changes. As mentioned above, the threshold voltage of the inverter 13 is approximately 1/2 of the operating voltage CC. Further, the "H" level output of the inverter 13 is approximately equal to the operating voltage ycc. Therefore, when the operating voltage Vcc changes, the output voltage of the inverter 13 for charging the capacitor 16 changes, and the slope of the rise and fall of the terminal voltage of the capacitor 16 changes.
The threshold voltage of the inverter 13 changes and
The timing of switching from "L" to "S" to "H11" changes. That is, the oscillation frequency and duty ratio of the multivibrator 1 change, and the output current changes. The above operation is performed in a negative feedback manner, and the output current is stabilized even against load fluctuations.

FIG. 3 shows a circuit configuration of a high voltage power supply device according to still another embodiment of the present invention. The device shown in the figure differs from the device shown in FIG.
A DC voltage created by rectifying and smoothing the voltage induced in the tertiary winding 3d is applied to the output terminal of the inverter 13 together with a voltage obtained by dividing the input voltage Va. .

Further, in this device, the output of the multivibrator 1 is supplied from the output end of the inverter 12 via the inverter 14 to the base of the transistor 2 connected to Darlington.

According to the device shown in FIG. 3, the same output stabilization (compensation) operation that was performed in accordance with fluctuations in the input voltage VB in the device shown in FIG. 1 is performed also in accordance with fluctuations in the output voltage. , the output voltage is stabilized against both input voltage and load fluctuations.

[Effects of the Invention] As described above, according to the present invention, the active elements have a very simple configuration of three inverter circuits (1/2 to 1 in case of IC) and one transistor or several transistors. A high-voltage power supply device with stabilized output can be constructed. Further, since this device stabilizes the output by controlling the pulse width like a switching regulator or the like, the device can be made compact. Further, the device of the present invention has a simple circuit configuration and is small in size as described above, and therefore is inexpensive.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a high-voltage power supply according to an embodiment of the present invention, FIG. 2 is a circuit diagram of a high-voltage power supply according to a third embodiment of the present invention, and FIG. FIG. 7 is a circuit configuration diagram of a high voltage power supply device according to another embodiment. 1...Unstable multivibrator. 11, 12.13...Digital inverter, 14, 1
5... Resistor, 16... Capacitor, 2... Transistor, 3... Step-up transformer, 6... Input voltage compensation circuit, 61... Variable resistor, 62... Diode, 63...
...resistor, 7...feedback circuit, 71...constant voltage circuit, 76...output current detection circuit,
11... Operating voltage control transistor.

Claims (1)

[Claims] 1. An unstable multivibrator configured using a DC power supply and a plurality of digital inverters, a switching circuit that is turned on and off by the output of this astable multivibrator, and driven by this switching circuit. and a step-up transformer supplied with power from the DC power supply, the high voltage power supply device generating a high-voltage, high-frequency voltage from the DC power supply, and dividing the voltage of the DC power supply and applying it to the unstable multivibrator. A high-voltage power supply device comprising an input voltage compensation circuit that varies the frequency and duty ratio of the unstable multivibrator. 2. The unstable multivibrator includes first to third inverters connected in cascade, and a capacitor connecting the output end of the second inverter and the input end of the first inverter;
a first resistor connecting the output end of the third inverter and the input end of the first inverter, and the input voltage compensation circuit includes a variable resistor or at least two resistors that divides the output voltage of the DC power supply. The high voltage according to claim 1, comprising a series circuit of resistors, and a second resistor connecting the sliding terminal of the variable resistor or the connection point between the resistors and the output end of the third inverter. power supply. 3. A DC power supply, an astable multivibrator configured using multiple digital inverters, a switching circuit that is turned on and off by the output of this astable multivibrator, and a switching circuit that is driven by this switching circuit to generate electricity from the DC power supply. A high-voltage power supply device that generates a high-voltage, high-frequency voltage from the DC power supply, comprising a step-up transformer to which power is supplied, and divides the output voltage V_B of the DC power supply and applies it to the unstable multivibrator. An input voltage compensation circuit that varies the frequency or duty ratio of the stable multivibrator, and an operating power source for the digital inverter by detecting the secondary induced output of the step-up transformer or the current, power, or voltage supplied from the step-up transformer to the load. A high-voltage power supply device comprising: a feedback circuit that controls voltage Vcc and varies the frequency or duty ratio of the unstable multivibrator. 4. The unstable multivibrator includes first to third inverters connected in cascade, and a capacitor connecting the output end of the second inverter and the input end of the first inverter;
a first resistor connecting the output end of the third inverter and the input end of the first inverter, and the input voltage compensation circuit includes a variable resistor or at least two resistors that divides the output voltage of the DC power supply. Claim 3 comprising a series circuit of resistors, and a second resistor connecting the sliding terminal of the variable resistor or the connection point between the resistors and the output end of the third inverter. High voltage power supply. 5. A DC power supply, an astable multivibrator configured using multiple digital inverters, a switching circuit that is turned on and off by the output of this astable multivibrator, and a switching circuit that is driven by this switching circuit to generate electricity from the DC power supply. A high-voltage power supply device that generates a high-voltage, high-frequency voltage from the DC power supply, and is equipped with a step-up transformer to which power is supplied, and divides the output voltage of the DC power supply and applies it to the unstable multivibrator. An input voltage compensation circuit that varies the frequency or duty ratio of the multivibrator, and detects the secondary induced output of the step-up transformer or the current, power, or voltage supplied from the step-up transformer to the load and applies it to the astable multivibrator. and a feedback circuit that varies the frequency or duty ratio of the unstable multivibrator. 6. The unstable multivibrator includes first to third inverters connected in cascade, and a capacitor connecting the output end of the second inverter and the input end of the first inverter;
a first resistor connecting the output end of the third inverter and the input end of the first inverter, and the input voltage compensation circuit includes a variable resistor or at least two resistors that divides the output voltage of the DC power supply. a series circuit of resistors, and a second resistor that connects the sliding terminal of the variable resistor or the connection point between the resistors and the output end of the third inverter,
The high voltage power supply device according to claim 5, wherein the detection output terminal of the feedback circuit and the output terminal of the third inverter are connected via a third resistor.