JPH11167241A - Multicolor image forming device and high voltage output method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an inexpensive multicolor image forming device small in size and light in weight, having plural developing units and electrifying devices. SOLUTION: This device is, provided with only one high voltage output device. The voltage generated by one high voltage output device 13 is input to respective DC bias circuits 14, 16 and 18 disposed in respective printing units on an electrifying device 5, developing device 6, auxiliary electrifying device 7, or the like. The respective DC bias circuits 14, 16 and 18 rectify the voltage being input from the high voltage output device 13 in accordance with respective connected units for printing, and output respectively to output control circuits 15, 17 and 19. The respective output control circuits 15, 17 and 19, are allowed to generate DC bias by stepping down the DC bias from the voltage being input from respective DC bias circuits 14, 16 and 18, and to feed the DC bias to the electrifying device 5, the developing device 6 and the auxiliary electrifying device 7.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multicolor image forming apparatus and a high-voltage output method therefor, and more particularly, to developing a toner image on a photosensitive drum after an electrostatic latent image is formed. The present invention relates to a multi-color image forming apparatus configured to apply a high voltage to each of a plurality of printing units such as a container and a high-voltage output method thereof.

[0002]

2. Description of the Related Art FIG. 6 is an explanatory view showing the structure of a developing unit and its peripheral elements of an image forming apparatus such as a multi-color copying machine which is generally used in the past.

In FIG. 1, reference numeral 1 denotes a charger high-voltage output device for applying a high voltage to the charger 5, and reference numeral 2 denotes a high-voltage output device for developing device DC bias that applies a high voltage to the developing device 6. Reference numeral 3 denotes a high voltage output device for applying a high voltage to the auxiliary charger 7, and a DC bias for the auxiliary charger 7. Reference numeral 4 denotes a photosensitive drum.

For each of the charger 5, the developing device 6, and the auxiliary charger 7, a predetermined voltage is supplied to each of the components from the high voltage output devices 1 to 3 provided one for each component. Is supplied, and charged toner adheres to the developing device. The attached toner is attached to the photosensitive drum 4 in accordance with the electrostatic latent image on the photosensitive drum 4, whereby a toner image is formed.

In the case of an image forming apparatus such as a multi-color copying machine, the applied voltage needs to be controlled for each color because the properties of the toner differ depending on the color. Therefore, generally, in an image forming apparatus such as a multi-color copying machine, one high-voltage output device is provided for each of a plurality of developing devices and a plurality of charging devices provided for each color.

FIG. 7 is an electric circuit diagram showing a circuit configuration of a conventional high-voltage output device employed in such an image forming apparatus.

In FIG. 1, a high-voltage output device 1 for DC bias of a charger includes an error amplifier 8 and an oscillator (OSC).
9, a control circuit 10, a converter transformer 11, a control signal input terminal 12, resistors R1 to R8, a transistor Q1, diodes D1 and D2, a varistor CR1, and capacitors C1 and C2. .

A power supply voltage of 24 V is applied to one end of the primary coil of the converter transformer 11. The error amplifier 8 is a two-input type amplifier. A control input signal is input to one input terminal via a resistor R1, and the other input terminal is a variable resistor R5 to detect an output voltage of the step-down output device 1. Connected to R7. The output side of the error amplifier 8, the base side of the transistor Q1, and the oscillator 9 are connected to the control circuit 10, and the transistor Q1
Is connected to the primary side of the converter transformer 11. One end of the secondary coil of the converter transformer 11 is connected to an output terminal for outputting a high voltage to the charger 5, and the other end is grounded.

The output of the error lamp 8 and the output of the transmitter 9 are controlled by the control circuit 10, and the transistor Q1 controls the converter transformer 11 according to the control result. According to the control result of the transistor Q1, the power generated on the secondary side of the converter transformer 11 is rectified and smoothed by the diode D2 and the capacitor C2, and then supplied to the charger 5.

The output voltage is detected by resistors R5 to R7, and the detected voltage is input to one input terminal of error amplifier 8. A control signal is input to the other input terminal of the error amplifier 8 via the resistor R1, and a signal generated by the control circuit 10 is changed according to a difference voltage between the control signal and the detection voltage. Stabilization is achieved.

The varistor CR1 has an overvoltage of the charger 5
Is provided as a constant-voltage element so as not to be applied to the power supply.

The high voltage output device 2 for developing device DC bias and the high voltage output device 3 for auxiliary charger DC bias are shown in FIG.
Is configured similarly to the high voltage output device 1 for DC bias of the charger shown in FIG.

[0013]

However, the conventional multi-color image forming apparatus requires, as described above, high-voltage output devices of the same number as the total number of developing units and charging units provided for each color. Become. Therefore, there is a problem that the image forming apparatus becomes large and expensive.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is an object of the present invention to provide a multicolor image forming apparatus having a plurality of developing units and a charging unit, which can be reduced in size, weight, and cost. It is an object of the present invention to provide a multicolor image forming apparatus and a high-voltage output method thereof.

[0015]

According to a first aspect of the present invention, there is provided a multi-color image forming apparatus having a plurality of printing units different for each color. High voltage output means for generating and outputting a voltage,
DC bias means provided one for each of the plurality of printing units; and output control means provided one for each of the plurality of printing units, wherein the DC bias means The output unit is configured to rectify the output voltage input from the output unit according to the printing unit and send the output voltage to the output control unit, and the output control unit converts the output voltage rectified by the DC bias unit into the printing unit. The DC bias is generated by stepping down the DC bias corresponding to.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the output control means controls a drawing current flowing between the high voltage output means and the printing unit. It has a control element.

According to a third aspect of the present invention, in the image forming apparatus of the first or second aspect, the plurality of units for print output include a developing device and a charging device. I do.

According to a fourth aspect of the present invention, there is provided a high-voltage output method for a multicolor image forming apparatus having a plurality of printing units which are different for each color. Generated, between the high-voltage output means and the printing unit, to generate a DC from the generated high voltage according to the printing unit, and to reduce a DC bias according to the printing unit from the DC voltage. It is characterized by generating.

According to a fifth aspect of the present invention, there is provided the high-voltage output method for a multicolor image forming apparatus according to the fourth aspect, wherein the generated high voltage is transmitted between the high-voltage output means and the printing unit. The step-down is performed by controlling the flowing current.

According to a sixth aspect of the present invention, in the high-voltage output method for a multicolor image forming apparatus according to the fourth or fifth aspect, the plurality of units for print output include a developing device and a charger. It is characterized by the following.

[0021]

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

FIG. 1 is a block diagram showing a configuration of a main part of the image forming apparatus according to the present embodiment. In the figure, the same components as those in FIG. 6 described above are denoted by the same reference numerals.

In the present embodiment, the same number of high-voltage output devices as a plurality of chargers and developing devices are not provided as in the prior art, but a plurality of chargers 5, a plurality of developing devices, And a DC bias to be supplied to the plurality of auxiliary chargers 7.

In FIG. 1, the image forming apparatus includes one high-voltage output device 13 for generating and outputting a high-voltage output required for image formation, and a plurality of chargers 5 and 5 provided for each color.
a, 5b..., a plurality of developing devices 6 provided for each color,
6a, 6b... And a plurality of auxiliary chargers 7, 7a, 7b. In the following description,
The configuration of one color among a plurality of chargers, developing devices, and auxiliary chargers will be described.

Between the high voltage output device 13 and the charger 5,
A DC bias circuit 14 and an output control circuit 15 are provided. A DC bias circuit 16 and an output control circuit 17 are arranged between the high-voltage output circuit 13 and the developing device 6, and a DC bias circuit 18 and an output control circuit are provided between the high-voltage output circuit 13 and the auxiliary charger 7. 19 are arranged.

The voltage generated by the high voltage output device 13 is input to DC bias circuits 14, 16, and 18 provided for each printing unit such as the charger 5, the developing device 6, and the auxiliary charger 7. DC bias circuits 14, 16 and 18
The AC voltage input from the high voltage output device 13 is rectified and output to the output control circuit 15 as a DC bias.

The output control circuit 15 includes the DC bias circuit 1
The DC bias generated by reducing the voltage from the DC bias input from 4 to a voltage value suitable for the connected printing output unit is supplied to each of the charger 5, the developing device 6, and the auxiliary charger 7.

FIG. 2 is a diagram showing a circuit configuration of the high-voltage output device 13 shown in FIG. In FIG.
The same components as those described above are denoted by the same reference numerals.

The high voltage output device 13 includes an operational amplifier 8, a control circuit 10, a converter transformer 11, and a resistor R11.
To R16, the transistor Q11, and the diode D11
And capacitors C11 and C13.

The operational amplifier 8 is a two-input type amplifier. A power supply voltage of 24 V is applied to one input terminal via R11, and a control circuit 10 is connected to the other input terminal. The control circuit 10 is connected to the output side of the operational amplifier 8. The base of the transistor Q11 is connected to the control circuit 10, and the transistor Q1
One collector side is connected to one end of a primary coil of the converter transformer 11. The secondary coil of the converter transformer is connected to an output terminal S11 that outputs an HVAC signal that is a high-voltage output. A power supply voltage of 24 V is applied to the transformer 11 via a resistor R16.

In the above configuration, the operational amplifier 8, the resistor R
11, R12, R13, R14 and the capacitor C11 constitute an oscillation circuit, and the oscillation waveform generated at C11 is input to the control circuit 10. Further, the control circuit 10 performs switching of the transistor Q11 according to the input oscillation frequency.
The high voltage generated at 1 is controlled. The high voltage generated in converter transformer 11 is output from output terminal S11 as an HVAC signal.

FIG. 3 shows a DC bias circuit 14 and an output control circuit 1 provided between the high voltage output device 13 and the charger 5 for supplying a DC bias suitable for the charger 5.
5 is an electric circuit diagram showing the configuration of FIG.

In the figure, the DC bias circuit 14
Resistors R21 and R22, capacitors C21 and C22,
It is a rectifier circuit composed of diodes D21 and D22. The HVAC signal output from the output terminal S11 of the high voltage generator 13 is input via the capacitor C21, rectified by the DC bias circuit 14, and then input to the output control circuit 15 via the resistor R29.

The output control circuit 15 includes a transistor Q21 as a current control element, a control circuit 22, an error amplifier 23, resistors R24 to R27, and a capacitor C23. The resistor 24 is connected to an output terminal S21 that outputs a DC bias current to the charger 5, and the output voltage to the charger 5 is detected via resistors R23, R24, and R25.

The detected output voltage is supplied to the error amplifier 23
Is input to the + input terminal. An analog signal from a sequence control circuit (not shown) is input to the-input terminal of the error amplifier 23 as an output control signal via an input terminal S22. The error amplifier 23 compares the input detection voltage with the output control signal, and compares the result with the control circuit 2.
Send to 2.

The capacitor C25 is a phase guarantee capacitor.

The base side of the transistor Q21 is connected to the control circuit 22. The control circuit 22 changes the current drawn into the transistor Q21 by controlling the base current according to the result input from the error amplifier 23. At this time, the output voltage detected by the resistor R24 can be stabilized by adopting the configuration of the negative feedback circuit. That is, the high voltage supplied to the charger 5 can be changed to a desired value by changing the output control signal.

An AC bias circuit comprising an oscillator 24, a driver 25 of the oscillator 24, a transformer 26, and a capacitor C24 is provided between the output control circuit 15 and the output terminal S21. Although an AC bias is superimposed on the voltage, it is not the essence of the present invention, and a detailed description thereof will be omitted.

FIG. 4 shows a DC bias circuit 16 and an output control circuit 1 provided between the high voltage output device 13 and the developing device 6 for supplying a DC bias suitable for the developing device 6.
7 is an electric circuit diagram showing the configuration of FIG.

In the figure, the DC bias circuit 16
Resistors R31 and R32, capacitors C31 and C32,
It is a rectifier circuit composed of diodes D31 and D32. The HVAC signal output from the output terminal S11 of the high voltage generator 13 is input via the capacitor C31, rectified by the DC bias circuit 16, and then input to the output control circuit 17 via the resistor R33.

The output control circuit 17 includes a transistor Q31 as a current control element, a control circuit 28, an error amplifier 29, resistors R34 to R37, and a capacitor C33. The resistor R34 is connected to the output terminal S31 for outputting a DC bias current to the developing device 6 via the resistors R37 to R39, and the output voltage to the developing device 6 is detected via the resistors R34 and R37. .

The detected output voltage is supplied to an error amplifier 29
Is input to the + input terminal. An analog signal from a sequence control circuit (not shown) is input to the-input terminal of the error amplifier 29 as an output control signal via an input terminal S32. The error amplifier 29 compares the input detection voltage with the output control signal and sends the result to the control circuit 28.

The capacitor C35 is a capacitor for phase protection.

The base side of the transistor Q31 is connected to the control circuit 28. The control circuit 28 changes the current drawn into the transistor Q31 by controlling the base current according to the result input from the error amplifier 29. At this time, the output voltage detected by the resistor R37 can be stabilized by adopting the configuration of the negative feedback circuit. That is, the high voltage supplied to the developing device 6 can be changed to a desired value by changing the output control signal.

An AC bias circuit including an oscillator 31, a driver 30 for the oscillator 31, a transformer 32, and a capacitor C35 is provided between the output control circuit 17 and the output terminal S31. Although an AC bias is superimposed on the voltage, it is not the essence of the present invention, and a detailed description thereof will be omitted.

FIG. 5 shows the high-voltage output device 13 and the auxiliary charger 7
FIG. 3 is an electric circuit diagram showing a configuration of a DC bias circuit 18 and an output control circuit 19 for supplying a DC bias suitable for an auxiliary charger 7 provided between the DC power supply and the auxiliary charger 7.

In the figure, the DC bias circuit 18
Resistors R41 and R42, capacitors C41 and C42,
The rectifier circuit 33 includes diodes D41 and D42. Output terminal S11 of high voltage generator 13
Is input through a capacitor C41, rectified here, and then input to the output control circuit 19 through a resistor R44.

The output control circuit 19 comprises a transistor Q41 as a current control element, a control circuit 34, an error amplifier 35, resistors R46 and R47, and capacitors C44 and C45. The resistance R43 is equal to the resistance R
The output terminal 45 is connected to an output terminal S41 for supplying a DC bias to the auxiliary charger 7 through 45, and the output voltage to the auxiliary charger 7 is detected via resistors R43 and R46.

The detected output voltage is supplied to the error amplifier 35
Is input to the + input terminal. A DC control signal, which is an analog signal from a sequence control circuit (not shown), is input to a negative input terminal of the error amplifier 35 via a resistor R47. The error amplifier 35 compares the input detection voltage with the DC control signal, and sends the result to the control circuit 34.

The base side of the transistor Q41 is connected to the control circuit 34. The control circuit 34 changes the draw current of the transistor Q41 by controlling the base current according to the result input from the error amplifier 35. At this time, by using a configuration of the negative feedback circuit, the output voltage output via the resistor R45 can be stabilized. That is, the high voltage supplied to the auxiliary charger 7 is changed by changing the DC control signal.
It can be changed to a desired value.

As described above, according to the present embodiment, a plurality of printing output units such as a plurality of chargers, a plurality of developing devices, and a plurality of auxiliary chargers that require different applied voltages for each color are used. Even if it is equipped, it is not necessary to arrange the same number of high-pressure generators as printing units that are difficult to miniaturize.
One high pressure generator is sufficient. Therefore, the size, weight, and cost of the image forming apparatus can be reduced.

[0052]

As described above, according to the multicolor image forming apparatus of claim 1 or the high voltage output method of the multicolor image forming apparatus of claim 4, a high voltage is generated by one high voltage output means. Then, between the high-voltage output unit and the printing unit, a DC is generated from the generated high voltage according to the printing unit, and a DC bias corresponding to the printing unit is reduced from the DC voltage to generate the DC. I decided to
Even when a plurality of print output units requiring different applied voltages for each color are provided, a single high voltage generator can supply a high voltage to each print output unit. Therefore,
As a result, the size, weight, and cost of the image forming apparatus can be reduced.

According to the multicolor image forming apparatus of claim 2 or the high voltage output method of the multicolor image forming apparatus of claim 5, the generated high voltage is transmitted between the high voltage output means and the printing unit. Since the step-down current is controlled by controlling the draw current flowing between the units, a high voltage suitable for the characteristics of each print output unit can be obtained without using a large device, in addition to the effects of the above-described claim 1 or 4. Can be easily supplied to each print output unit.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a main part of an image forming apparatus according to an embodiment of the present invention.

FIG. 2 is an electric circuit diagram showing a circuit configuration of the high-voltage output device 13 shown in FIG.

FIG. 3 is provided between the high-voltage output device 13 and the charger 5 to supply a DC bias suitable for the charger 5;
FIG. 2 is an electric circuit diagram illustrating a configuration of a DC bias circuit and an output control circuit.

FIG. 4 is provided between the high-voltage output device 13 and the developing device 6 to supply a DC bias suitable for the developing device 6;
FIG. 2 is an electric circuit diagram showing a configuration of a DC bias circuit 16 and an output control circuit 17.

FIG. 5 is an electric circuit showing a configuration of a DC bias circuit 18 and an output control circuit 19 provided between the high voltage output device 13 and the auxiliary charger 7 for supplying a DC bias suitable for the auxiliary charger 5; FIG.

FIG. 6 is an explanatory view showing a configuration of a developing unit and its peripheral elements of an image forming apparatus such as a multi-color copying machine which is generally used conventionally.

7 is an electric circuit diagram showing a circuit configuration of a conventional high-voltage output device employed in the image forming apparatus shown in FIG.

[Explanation of symbols]

 Reference Signs List 5 charger 6 developing device 7 auxiliary charger 13 high voltage output device 14, 16, 18 DC bias circuit 15, 17, 19 output control circuit

Claims (6)

[Claims] 1. A multi-color image forming apparatus having a plurality of printing units that are different for each color, a high-voltage output unit that generates and outputs one high voltage, and one for each of the plurality of printing units. DC bias means provided for each of the plurality of printing units, and output control means provided for each of the plurality of printing units. The DC bias means prints the output voltage input from the high-voltage output means. The output control means is configured to rectify and send to the output control means according to a unit, and the output control means reduces and generates a DC bias corresponding to the printing unit from the output voltage rectified by the DC bias means. An image forming apparatus comprising: 2. An image forming apparatus according to claim 1, wherein said output control means has a control element for controlling a drawing current flowing between said high voltage output means and said printing unit. 3. The unit according to claim 1, wherein the plurality of units for print output include a developing device and a charging device.
Or the image forming apparatus according to 2. 4. A high-voltage output method for a multi-color image forming apparatus having a plurality of printing units that are different for each color, wherein a high voltage is generated by one high-voltage output unit, and between the high-voltage output unit and the printing unit. And generating a direct current from the generated high voltage in accordance with the printing unit, and lowering and generating a direct current bias corresponding to the printing unit from the direct current voltage. 5. The step of reducing the generated high voltage by controlling a draw current flowing between the high voltage output means and the printing unit.
High voltage output method as described. 6. The printing device according to claim 4, wherein the plurality of units for printing output include a developing device and a charging device.
Or the high voltage output method according to 5.