JPH0446560A - power supply - 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 [Field of Industrial Application] The present invention relates to a power supply device used as a switching regulator in electrophotographic copying machines, printers, and the like.

(Prior Art) Conventionally, electrophotographic copying machines, printers, etc. have used switching regulators with voltage resonance flyback transformers as power supplies. The polarity of the output rectified output is determined, and for example, if it is used as a power source for a transfer device, it is biased with the opposite polarity to the developer.In this case, when the developer is on the photoconductor, the polarity of the rectified output is determined. If there is no rolling paper, the transfer device or developer may get dirty, and the back side of the transfer paper may become dirty.Especially, if the roller is a contact type roller, the stains will be severe.Therefore, in order to prevent this, During periods when there is no transfer paper, a reverse bias is applied to the transfer device to clean it.

[Problem to be solved by the invention]

However, in a power supply device configured as a conventional switching regulator, the output polarity is fixed as described above, so when used for a transfer device, for example, a power supply or transformer is required to generate the bias used for normal transfer. A power supply or transformer is required to generate the bias used for cleaning.
There was a problem that the equipment became larger and more expensive.

The present invention has been made with attention to such problems, and it is possible to obtain any output polarity from positive to negative with the same converter transformer, making it possible to reduce the size and cost of the device. The purpose is to obtain a power supply device.

[Means to solve the problem]

The power supply device of the present invention is constructed as follows.

1. In a power supply device having a converter transformer whose primary side is switching controlled, a diode for obtaining a positive polarity output on the secondary side of the converter transformer;
The negative polarity output opposite to that output is 14? A diode was connected to the output terminal to supply a mixed output of both polarities to the load.

II. In the aforementioned power supply device, one end of the secondary winding of the converter transformer was grounded, and each half-wave rectifier diode was connected to the other end to obtain a bipolar output.

In the power supply devices listed in Items M and H, each diode for obtaining a bipolar output is connected to one end of the secondary winding of the converter transformer, and a diode for rectifying the return current from the load is connected to the other end. Connected.

(Function) In the power supply device of the present invention, respective diodes for obtaining different output polarities are connected to the same converter transformer, and outputs of positive polarity and negative polarity can be obtained.

Then, these bipolar outputs are mixed and output to the load.

〔Example〕

FIG. 1 is a circuit diagram showing the configuration of a power supply device according to a first embodiment of the present invention. In the figure, Tl0I is the voltage resonance ft
, Q, the primary side of which is a flyback transformer is connected to a 24V DC chamber ffxVcc, and is driven by a switching transistor Tr101.

Primary right line T101a of this converter transformer T101
In addition to the transistor TrlO1, a resonance capacitor Cl0I and a diode DIOI are connected in parallel, and a secondary winding 7101b is connected to the secondary side to provide the positive Jut output (flyback output). A seventh-order winding T101c is provided to obtain an output (forward output) of negative polarity opposite to that output. Then, a rectifying diode DI0 is connected to each of the next windings 7101b and T101c.
3. D104 and IV Namekawa capacitor ClO3, ClO
4 are connected, and resistors RIOI and R103 are connected between the output terminals of each secondary winding 7101b and T101c, respectively.

Also, one output end of the secondary winding 7101b is connected to the load +02
The other output terminal is connected to one output terminal of the secondary winding T101c via the resistor R102, and the other 110,000 terminal of this secondary winding 191T101c is connected to the resistor R1.
05 to the connection point of the series circuit of resistors R104 and R106.

And 24V DC chamber ll connected to resistor R106
l! I! V c c applies a bias to the other output terminal of the primary wire T 101 c through the resistor R105, and each secondary winding Tl01b, T1
The bipolar outputs from 01c to fJ are mixed by the resistor circuit 41 made of the above-mentioned resistors and are supplied to fs/:r t02.

101 is controlled from a foreign controller 4JS101
A PWM circuit that drives (on, off) the switching transistor TrlO1 manually inputs the voltage appearing on the resistor R105, and outputs a PWM signal corresponding to the human input to the switching transistor Tr101 to control the load 1.
The current flowing through 02 is controlled to be constant.

Next, the operation will be explained.

The PWM circuit 101 switches the switching transistor Tr101 according to a control signal 5101 from an external controller.
A PWM signal is output to drive the converter transformer T101. As a result, as described above, a positive polarity flyback output and a negative polarity forward output are obtained on the secondary side of the converter transformer T101, and these bipolar outputs are mixed by the resistor circuit and supplied to the load 102. Ru. At this time, a feedback voltage corresponding to the load current is manually applied to the PWM circuit 101, and the current flowing through the load 102 is controlled to be constant.

FIG. 2 shows the relationship between the flyback output and forward output when the pulse width of the PWM signal output from the PWM circuit 101 to the switching transistor TrlO1 is changed.

As shown in the figure, the positive polarity flyback output increases at a constant level as the pulse width increases,
Negative forward output is converter transformer T101
When the operation is stable, it is hardly affected by the pulse width. Therefore, in the circuit shown in Figure 7JJ1, the load 102
Since the voltage supplied to is the sum of the above-mentioned positive polarity output and negative polarity output, the output is as shown by the dotted line in FIG. That is, by performing PWM control within the control range shown in FIG. 2, the output supplied to the load 102 can be freely changed from positive to negative.

In this way, any output polarity from positive to negative can be obtained with the same converter transformer T101, so when used as a bias power source for the transfer device of an electrophotographic copying machine, for example, control number 48 from the controller can be used. 51
By controlling 01, it is possible to control from a normal transfer bias to a cleaning reverse bias. Therefore, it is possible to reduce the size and cost of the device.

FIG. 3 is a circuit diagram showing a second embodiment of the present invention. In the embodiment shown in FIG. 1 above, two secondary windings are provided on the secondary side of the converter transformer, or in this embodiment, two secondary windings 720 l b are provided on the secondary side of the converter transformer T2O1.
A diode D103 for obtaining a positive flyback output and a diode D104 for obtaining a negative forward output are connected in parallel to the secondary winding 720 lb. Then, the output end nails of both poles of jFf'1 are connected to resistors R1ot and R103, which are pseudo loads, and between them, the straight 3'1 of resistors R201 and R202 are connected.
1 circuit is connected, and these resistors R201 and R202
The connection point of is connected to negative σr102. Further, a DC power supply VCC and a switching transistor TrlO1 are connected to the primary winding 7201a of the converter transformer T2O1, and the other configuration is the same as that of the circuit shown in FIG.

In the circuit shown in FIG. 3, one end of the secondary winding 7201b of the converter transformer T2O1 is grounded through the resistor R104R105, and the other end is connected to each half-wave rectifier TIO 1"D103 to obtain a bipolar output. .D104 is connected, and as in the circuit of FIG.
' A negative forward output is generated by the rectifying and smoothing circuit of D104 and capacitor ClO4. These bipolar outputs are then added together by a resistor circuit and supplied to the f's load 102.

Here, if the resistance values of the low resistances R201 and R202 are the same, the voltage supplied to the load 102 is
The potential is intermediate between the positive voltage and the negative voltage generated in the P-slip circuit. Therefore, the positive and negative polarity outputs when PWM control is performed are the same as in the embodiment shown in FIG.
The output obtained by mixing the two becomes a voltage as shown by the dotted line in FIG. That is, in the embodiment shown in FIG. 3, it is important to control the output from the positive electrode to the negative electrode,
The same effects as the embodiment shown in FIG. 1 can be obtained. Further, in this embodiment, compared to the embodiment shown in FIG. 1, there is no need to provide separate secondary windings for the positive and negative poles of the converter transformer, and further, the converter transformer T2O1 can be made smaller.

Note that, like FIG. 2, FIG. 4 shows the output waveform of the circuit in FIG. 3.

FIG. 5 is a circuit diagram showing a third embodiment of the present invention. In this embodiment, each of diodes D103 . D104 is connected to the other end of the diode D301.D104, which rectifies the return current from the load 102. D302 is connected. Further, a DC power supply VCC and a switching transistor Tr101 are connected to the primary winding T301a of the converter transformer T301, and the other configurations are the same as those in FIG. 1 or FIG. 3.

In the circuit of FIG. 5, a diode D103.
A positive flyback output is generated by the rectifying and smoothing circuit of D301 and capacitor ClO3, and the diode D104.
A forward output of negative polarity is generated by a rectifying and smoothing circuit including D302 and capacitor ClO4, and these outputs of both polarities are added and supplied to the load 102. The other operations are similar to those of the circuit shown in FIG. 1.

Here, the output when PWM control is performed with the circuit of FIG. 5 is the same as that of the circuit of FIG. 1, and the converter transformer T30
Even if there is only one secondary winding T301b, the circuit has the same performance as the circuit shown in FIG. 1, and the output variable width is also the same.

Therefore, even with such a configuration, the same effects as those of the embodiments described in L can be obtained.

In each of the above embodiments, the positive polarity output is used as the flyback output and the negative polarity output is used as the forward output, or conversely, the positive polarity is generated from the forward output and the negative polarity is generated from the flyback output. It's okay.

〔Effect of the invention〕

As described above, according to the present invention, diodes for obtaining positive and negative outputs are connected to the secondary side of the converter transformer, and the 71 forces of both polarities are mixed and supplied to the load. Therefore, any output polarity from positive to negative can be obtained with the same converter transformer, and the device can be made smaller and lower in cost.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing the first embodiment of the present invention, FIG. 2 is an output waveform diagram of the circuit of FIG. 1, and FIG. 3 is a circuit diagram showing the second embodiment of the present invention. 41A is an output waveform diagram of the circuit shown in FIG.'dX3, and FIG. 5 is a circuit diagram showing a third embodiment of the present invention. 101...PWM circuit 102...Load ClO3, ClO4...Capacitor 11 Applicant
Canon Co., Ltd. Ne1 TrlOl...Switching transistor Tl
0I T101a T101b, T101c r101 C103C104 C103C104 R101~R106 Conharter transformer - dog shoulder I T 201 b R201, R202 Compa'-Futrans-Kumaki f made of 22 8 stitches\coarse- NiJ≦--%a month-) Mine 2 * Woit! jrJ Inner J Self-Rainbow 3$ 3 Also, Fig. 2 301a 301b C301, 0302 Humbuck transformer-blown winding wire varnish winding diode wire removal/) A 3 branch example-Lecture box 57

Claims (3)

[Claims] (1) In a power supply device having a converter transformer whose primary side is switching controlled, a diode is provided on the secondary side of the converter transformer to obtain a positive polarity output, and a diode to obtain a negative polarity output opposite to that output. 1. A power supply device characterized by connecting a diode and supplying a mixed output of these bipolar outputs to a load. (2) One end of the secondary winding of the converter transformer is grounded, and each half-wave rectifier diode is connected to the other end to obtain a bipolar output.
Power supply listed. (3) A diode for obtaining a bipolar output is connected to one end of the secondary winding of the converter transformer, and a diode for rectifying the return current from the load is connected to the other end. The power supply device according to claim 1.