JPS62277026A - Electric source - 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] 3. Detailed Description of the Invention [#: Field of Use of χF] The present invention relates to a power supply device, and particularly to a power supply device that generates high-voltage alternating current.

[Prior Art] Conventionally, AC high-voltage power supplies have a configuration in which AC output from a commercial power supply or a switching circuit is increased to >1 voltage using a step-up transformer.

[The problem that Part 1 attempts to solve] However, in the charging process of electrophotographic processes such as copying machines, IK)
High-voltage AC with a power frequency below Iz is required,
A 4-voltage transformer for such a low frequency is extremely large and requires a power supply circuit.

It was extremely difficult to reduce the size and weight of the entire device.

In particular, copying machines and the like sometimes require amplitude and phase control of high-voltage AC output during charging and developing processes, and when such a control circuit is provided, there is a problem that the apparatus tends to become larger.

[Means for Solving the Problems] In order to solve the above problems, the present invention includes a plurality of DC power supplies whose output voltages can be controlled, each of which switches the DC power supply voltage, and the output of one switching means. A step-up circuit consisting of multiple stages of switching means connected to form a common line for the next-stage switching means is provided, and each switching means switches each DC power supply voltage in the same phase, so that the switching means of the final stage can A configuration was adopted in which a boosted AC output is obtained and the #i width of the high voltage AC output at the final stage is controlled by controlling the output voltages of the plurality of DC power supplies.

[Function] According to the above configuration, each switching stage turns on and off multiple DC power supplies synchronously, and by connecting their outputs in series, a high voltage whose amplitude is the sum of the DC power supply voltages is generated. AC output can be obtained, and by controlling the output of the DC power supply, the amplitude of the high voltage AC output can be controlled.

[Example] The present invention will be described in detail below based on an example shown in one drawing.

Figure 1 shows an embodiment of the power supply circuit according to the present invention, which basically consists of a pulse generator 1 that generates rectangular wave pulses.
It consists of two switching (amplification) circuits including transistors Tri and Tr2.

The pulse generator 1 generates a switching pulse suitable for the load, and inputs this as a switching control signal to the transistor Tri side via the resistor R11 and the terminal pH.

The two transistors Tri and Tr2 each have a resistor R
11NR15 and resistors R21 to R25 constitute a switching circuit, and the voltages of the isolated power supplies El and E2 are switched by their corephthal emitters based on the driving conditions defined by the respective resistors. The base of the transistor Trl is directly controlled by the pulse generator l via the resistors R11 and R12.
The base of the transistor TRI is connected to the common potential (here, ground potential) on the transistor TRI side via the resistor R21 and the terminal P21.

The switching output output from the collector of the transistor Tri is connected to the common potential of the switching circuit on the transistor Tr2 side via the terminal P12, and is further connected to the terminal P2 connected to the collector of the transistor Tr2.
The total output is taken out from 2.

In the above configuration, when the pulse generator 1 generates a pulse of a predetermined frequency, the transistor Tri is turned on/off by this pulse. Transistor Tr
Resistors R14 and R connected to the collector and emitter of i
15 is set to R14))R15, so terminal P1
The collector output voltage of transistor Tr 1c7) is approximately Ov when it is on and +EIV when it is off.

Since the output of the terminal P12 is the common potential on the transistor TrZ side, the base voltage of the transistor Tr2 is
The transistor Tr2 is biased so that when the common potential on the transistor TrZ side is Ov, the transistor Tr2 is turned on, and when the common potential moves toward EIV, the transistor Tr2 is turned off in the middle thereof.

The above operation causes terminal P12. The waveform of P22 is as shown in Figure 52 (A), transistor l.

Since Tr2 synchronously controls each voltage El and E2, when both transistors are on, both collector levels are O, and conversely, when both transistors are off, each transistor Tri,
The collector potential of Tr2 is El.

It becomes E2. As mentioned above, since the common line on the transistor TrZ side is connected to the output on the transistor Tri side, the total output of the terminal P22 is O~+(El+E2
) It becomes an alternating current high voltage with an amplitude range of V.

Note that during the above operation, the resistors R15 and R25 prevent the transistors Tri and Tr2 from becoming excessively saturated and reducing the switching speed. The respective power supply voltages El are applied to the corephthal emitters of the transistors Trl and Tr2.

A voltage exceeding R2 is never applied, and there is no risk of element destruction.

As described above, it is possible to obtain a small, lightweight, simple and inexpensive high-voltage AC power supply device without using a step-up transformer.

Since this embodiment does not use a step-up transformer, there is no need to consider problems based on transformer characteristics such as ringing, magnetic flux saturation, and overshoot due to resonance, so there is no need to increase the cost of the equipment, and there is no energy loss or output distortion. There is no need to worry about inviting such problems.

In the above, a switching circuit with two-stage connection was illustrated, but three
It is also possible to connect more than one stage of switching circuits to obtain a higher voltage.

The circuit shown in FIG. 3 has the configuration shown in FIG.
ry, and a switching circuit including resistors R31 and R32. The three stages of switching circuits are connected in the same way as described above so that the output of the previous stage becomes a common line of the latter stage.

According to the above configuration, the total output obtained from the terminal P32 is generated by the in-phase switching of Tri to Tri3 by each transistor, as shown in FIG.
This becomes an alternating current with an amplitude of (E1+E2+E3)V.

In the following manner, the same effect as described above can be obtained, and the output voltage can also be increased. Needless to say, it is possible to further increase the output by connecting four or more stages of switching circuits.

In the above example, we have shown a configuration that outputs high-voltage alternating current with a constant amplitude, but if it is necessary to change the output amplitude, the following configuration can be considered.It is necessary to control the amplitude by human power. A certain load may be a developing roller of an electrophotographic copying machine or a printer, and FIG. 4 shows the configuration of a power supply device as a developing bias generating circuit for this type of developing roller.

In the lower half of FIG. 4, two series-connected power supply blocks consisting of transistors Tri and Tr2 of the circuit of FIG. 3 are shown. As the power supply voltage of these power supply blocks, the AC output generated by the winding 13 of the transformer TI is connected to the diodes Di l , D12 (D21 , D2
2), capacitor C1l, C12 (C21, C22)
Voltages E1 and R2 which are voltage-doubled and rectified by are given respectively.

Here, the transformer Tl constitutes a known switching type power supply together with the oscillation circuit 3 connected to its winding 11, and has a winding 12 in addition to the winding 13, and this! !
The output of the c line is fed from the terminal HPI to another predetermined load via a rectifier circuit 4 consisting of a diode and a capacitor.

The output of the winding No. 3 is input to each itt block via a resistor Rbl, and the voltage at the output terminal of the resistor RbL can be controlled by a transistor Tr3. That is, the output terminal of the resistor Rbl is connected to the resistor Rb.
2. It is connected to the series circuit connected to the ground potential from the corephthalic emitter of the transistor Tr3 and the resistor Rb3.

The base of the transistor Tr3 is controlled by the output of the operational amplifier 5 via the resistor Rb4. One input terminal of the operational amplifier 5 receives the control voltage inputted through the terminal IPI and the resistor Rb7, and the input terminal E1 of the transistor T r 1 'JN(1') MIX block is inputted to the input terminal of the operational amplifier 5 through the resistor Rb5. ．． The image divided by Rb6 is input.

In the configuration 1- below, when the power supply by the transformer Tl is driven, the power is supplied to each power supply block including the transistors Tri and Tr2, and the pulse generating unit 1 is activated at the same time, the amplitude of the AC output obtained from the collector of the transistor Tr2 is As mentioned above, it matches + (El, R2)V with extremely high accuracy.

The alternating current of 15t applied to the collector of transistor Tr2 is
It is superimposed on the high voltage DC voltage output from the high voltage DC power supply 2 via the coupling capacitor Ca.

After level shifting, power is supplied from the terminal HP2 to a load such as a developing roller of a copying machine as a developing bias.

In the development process of a copying machine, etc., it may be necessary to independently control the AC and DC development biases, but in the above configuration, by changing the control voltage via the terminal IPI to the operational amplifier 5, the voltage at the terminal HP2 can be changed. The AC component of the output can be controlled.

That is, in the configuration north of this point, the operational amplifier 5 is connected to the resistor Rb5.
, the voltage El detected by Rb6 is compared with the single-handed control voltage, and the conductivity of the transistor Tr3 is controlled to change the voltage drop across the resistor Rbl, so that the voltage El,
It controls E2.

Therefore, the terminal IPI which is the threshold fd during comparison operation
By changing the input voltage of the terminal HP2, it is possible to control the AC component of the output of the terminal HP2 as desired.

[Effects] As is clear from the above description, according to the present invention, a plurality of mutually insulated DC power supplies, each of which switches the DC power supply voltage, and the output of one switching means is connected to the next stage switching means. A step-up circuit consisting of multiple stages of switching means connected to form a common line is provided, and each switching means switches the DC power supply voltage in the same phase, thereby obtaining a boosted AC output from the final stage switching means. By adopting this configuration, it is possible to obtain the desired high voltage AC according to the number of connected stages of the switching means, and since a Y1 voltage transformer is not required, there is no need to consider the problems that occur when using a transformer. Therefore, the circuit design becomes easy, and the power supply circuit and the entire device to be adopted can be made small, lightweight, simple and inexpensive, which is an excellent effect.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing the configuration of a power supply device employing the present invention, FIGS. 2A and 2B are waveform diagrams explaining the operation of the power supply device according to the present invention, and FIG. 3 is a circuit diagram showing the configuration of a power supply device according to the present invention. FIG. 4 is a circuit diagram showing a further different structure of a power supply device according to the present invention. l...Pulse generator 2...High voltage DC power supply 3...
・Oscillation circuit 4... Rectifier circuit 5... Operational amplifier Tri-Tr3... Transistors R1-R15, R21-R23, R31-R33...
Resistor El-E3...Power source Fig. 1 (A) (B) No. 1-7r, Shichoko 5 reflection] Bow Fig. 2

Claims (1)

[Scope of Claims] 1) A plurality of DC power supplies whose output voltages can be controlled, each switching the DC power supply voltage, and connected so that the output of one switching means becomes a common line for the next stage switching means. a step-up circuit consisting of a plurality of stages of switching means, each switching means switching each DC power supply voltage in the same phase to obtain a boosted AC output from the final stage switching means; A power supply device characterized in that the amplitude of a high-voltage AC output at the final stage is controlled by controlling the output voltage of a DC power supply. 2) The power supply device according to claim 1, further comprising means for inputting switching control signals to each of the switching means in a mutually insulated state. 3) Each switching control input terminal of the switching means in each stage is connected to the common line of the previous stage via a resistor, and the switching of each switching means is controlled by a change in potential difference between each common line and the switching control input terminal. A power supply device according to claim 1.