JP2001078468A - High-voltage outputting device, method for controlling high-voltage output, and image-forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To control the output of a high-voltage outputting device with serial data without causing circuits to malfunction. SOLUTION: A high-voltage outputting device is provided with a controller 1, which generates serial control data, a shift register 2 which converts the serial control data generated from the controller 1 into parallel control data, and a high-voltage generating circuit 7 which generates a high voltage. The outputting device is also provided with a plurality of high-voltage control circuits 6a-6h, which output prescribed control voltages by controlling the high voltage from the circuit 7 based on the parallel control data. The outputting device transfers the serial control data generated from the controller 1 to the shift register 2 at a high frequency, which is higher than a prescribed clock frequency and sets the converted parallel control data in a latch circuit selected by means of a decoder 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage output device, a high-voltage output control method, and an image forming apparatus, and more particularly, to a high-voltage output device for supplying a high voltage to a thermographic charger for image formation. And a high-voltage output control method, and an image forming apparatus such as an electrophotographic copying machine or a printer equipped with the high-voltage output device.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine or a printer, various high voltages are required in an image forming process. However, conventionally, a high voltage output device having a plurality of converter transformers has been conventionally used. Thus, a plurality of types of required high voltages are generated, and the high voltages are supplied to a plurality of high-voltage load devices such as a thermographic charger.

For example, in a color printer or a color copying machine that forms a full-color image by mixing four colors of yellow (Y), magenta (M), cyan (C), and black (K), a developing device for each color is used. A high voltage is supplied to a plurality of high-voltage load devices such as a printer and a transfer charger.

[0004] In such a case, the high voltage power supply circuit can be shared by supplying a high voltage from a single high voltage power supply circuit to a plurality of high voltage load devices. It is thought that cost reduction and cost reduction can be achieved.

However, since the timing and output voltage of the high voltage applied by the high-voltage load devices are different from each other, a high voltage is generated by the high-voltage generation circuit, while a plurality of high-voltage control devices corresponding to the number of the high-voltage load devices are generated. Circuit,
By controlling the output timing and output voltage of the high voltage by the high voltage control circuit based on the control signal output from the controller of the image forming apparatus, the high voltage generated by the high voltage generation circuit is transmitted from the high voltage control circuit. It supplies to each high voltage load equipment.

[0006]

The contents of control of an image forming apparatus have become more complicated and sophisticated with the recent demand for higher image quality. Therefore, high voltage load equipment to which a high voltage is supplied is required. Types are also increasing. Particularly, in a color printer or a color copying machine, a high-voltage load device is required for each color, and thus the number of control signals output from the controller is also increasing.

In addition, since the controller and the high-voltage generating circuit are usually usually incorporated into different circuit boards or units, the number of cables connecting the controller and the high-voltage generating circuit also increases.
Therefore, conventionally, there has been a problem that the downsizing of the device is hindered and the cost is increased.

In order to solve such a problem, a control signal output from the controller is converted into serial data,
A method of controlling a plurality of high-voltage outputs by one serial data is conceivable. In such a case, noise is generated from a high-voltage AC circuit or the like constituting a high-voltage generation circuit, and the noise is superimposed on the serial data to generate data. Because of the change, a problem that a malfunction of the high voltage generation circuit may be caused may newly arise.

The present invention has been made in view of such circumstances, and a high-voltage output device, a high-voltage output control method, and an image forming apparatus that enable control by serial data without causing a circuit operation to malfunction. The purpose is to provide.

[0010]

In order to achieve the above object, a high voltage output device according to the present invention comprises a serial data generating means for generating serial control data, and a serial control data generated by the serial data generating means. Data conversion means for converting into parallel control data, high voltage generation means for generating a high voltage, and a plurality of high voltage controls for controlling a high voltage from the high voltage generation means based on the parallel control data and outputting a predetermined control voltage Means, wherein the serial data generating means generates the output values of the plurality of high-voltage generating circuits so that data is sequentially and repeatedly input periodically, and generates the generated serial control data at a predetermined frequency or higher. Having a data transfer means for transferring the serial control data to the data conversion means at a high frequency. That.

Further, in the high voltage output control method according to the present invention, there is provided a serial data generating step for generating serial control data, and a data conversion for converting the serial control data generated in the serial data generating step into parallel control data. Step, a high voltage generating step of generating a high voltage, and a control voltage output step of controlling the high voltage based on the parallel control data and outputting a predetermined control voltage from the high voltage control means, further comprising the serial data The serial control data generated in the generation step is periodically repeated at a high frequency higher than a predetermined frequency. The method further includes a data transfer step of transferring the serial control data.

Further, an image forming apparatus according to the present invention is provided with the high-voltage output device.

The other features of the present invention will become apparent from the following description of embodiments of the present invention.

[0014]

Next, an embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a high-voltage output device according to the present invention. The high-voltage output device is divided into a control unit and a power supply unit, and a thermographic charger for image formation. For example, a high voltage is supplied to a plurality of high-voltage load devices built in the image forming apparatus.

That is, in FIG. 1, reference numeral 1 denotes a controller for performing a predetermined sequence control. The controller 1 generates a serial data signal, a clock signal, and a set signal. The set signal is supplied to the Di terminal and the CLK terminal, respectively, and the set signal is supplied to the set terminal of the decoder 3. The shift register 2 has 12 binary cells (D0 to D11) in which 1-bit information is set, respectively.
Each time a clock signal is input from the controller 1, the shift is performed by one digit.

Of the outputs of the binary cells, outputs D0 to D7 are connected to first to eighth latch circuits 4a to 4h, and bit signals from the outputs D0 to D7 are output to first to eighth latch circuits 4a. To 4h.

The outputs D8 to D1 of the shift register 2
1 is connected to the select terminal of the decoder 3 and the output D8
ＤD11 are input to the select terminal.

The decoder 3 includes first to eighth latch circuits 4a.
To 8h, and the bit signals input from the outputs D8 to D11 are supplied to one of the first to eighth latch circuits 4a to 4h selected by the set signal.

The first to eighth latch circuits 4a to 4h
Are respectively connected to the first to eighth D / A converters 5a to 5h, and the bit signals output from the first to eighth latch circuits 4a to 4h are respectively connected to the first to eighth D / A converters 5a to 5h.
h.

Further, first to eighth D / A converters 5
a to 5h are connected to first to eighth high-voltage control circuits 6a to 6h, respectively.
a to 6h are also connected to the high voltage generation circuit 7. The analog signals output from the first to eighth D / A converters 5a to 5h and the voltage signals output from the high-voltage control circuit 7 are supplied to the first to eighth high-voltage control circuits 6a to 6h. A high voltage is supplied from the first to eighth high-voltage control circuits 6a to 6h to high-voltage load devices (not shown) via the first to eighth high-voltage output terminals 11a to 11h.

FIG. 2 is an electric circuit diagram showing details of the high voltage generation circuit 7.

Reference numeral 8 denotes an oscillator. The oscillator 8 is input to a gate terminal of a field effect transistor (FET) Q via a resistor R1. The drain terminal of the FET Q is connected to one end of the primary winding of the converter transformer T. The primary winding of the converter transformer T has a bifarer winding structure, and the center tap is connected to a power supply (Vcc) via a resistor R2.
And grounded via a capacitor C1.

The other end of the primary winding of the converter transformer T is connected to the cathode terminal of the diode D1, the anode terminal of the diode D1 is grounded, and the oscillator 8 and the FET Q are connected via a resistor R3. It is connected to the midpoint of the gate terminal.

On the other hand, one end of the secondary winding of the converter transformer T is connected to the high voltage control circuit 6 (first to eighth high voltage control circuits 6a to 6h), and the other end is grounded.

In the high voltage generation circuit 7 configured as described above, the oscillator 8 generates an oscillation pulse at the driving frequency of the converter transformer T, and the FET Q performs a switching operation using the oscillation pulse as a trigger. That is, the converter transformer T is excited by the switching operation of the FET Q to generate a high AC voltage in the secondary winding, and the high AC voltage is applied to each of the high voltage control circuits (first to eighth).
To the high-voltage control circuits 6a to 6h).

FIG. 3 is an electric circuit diagram showing details of the high voltage control circuit 6.

The high voltage control circuit 6 includes capacitors C2 and C
3, and the diodes D2 and D3 constitute a rectifying / smoothing circuit 9. The high-voltage output output from the high-voltage generating circuit 7 is rectified and smoothed by the rectifying / smoothing circuit 9, and the negative-side output of the rectifying / smoothing circuit 9 is a high-voltage output. It is supplied to the high-pressure load device as it is via the output 11. Note that a resistor R4 is interposed between the positive output and the negative output of the rectifying / smoothing circuit 9.

The positive output of the rectifying / smoothing circuit 9 is connected to the collector terminal of the transistor Tr via a resistor R5, and the emitter terminal of the transistor Tr is connected to a resistor R6.
Grounded. The base terminal of the transistor Tr is connected to the output terminal of the operational amplifier 10 via the resistor 7. The positive input terminal of the operational amplifier 10 is connected to the high voltage output 11 and the power supply (Vcc) via the resistors R8 to R10, respectively, and is grounded via the diode D4.

The negative input terminal of the operational amplifier 10 is connected to the D / A converter 5 via a resistor R10, and the resistor R7 and the operational amplifier 1 are connected via a capacitor C5.
It is connected to an intermediate point with the output terminal of 0.

In the high voltage control circuit 6 configured as described above, assuming that the control voltage output from the D / A converter 5 is Vcont, the voltage at the high voltage output terminal 11, that is, the output voltage Vhvl is expressed by the following equation (1). expressed.

Vhvl = [Vcont × (R8 + R9) −Vcc × R10] / R8 (1) That is, the output voltage Vhvl is controlled by the control voltage Vcont.

FIG. 4 is a timing chart showing the operation of the high voltage output device of the present invention.

That is, as shown in FIGS. 4A and 4B, serial data is output in synchronization with a clock signal.
It is input to the Di terminal of the shift register 2. The shift register 2 sequentially shifts the input serial data through the 12-bit shift register 2 from D0 to D11 in synchronization with the clock signal, and converts the serial data into parallel data. Then, among the outputs of the shift register 2, the output D0
The 8-bit parallel data of D8 to D7 is input to any one of the first to eighth latch circuits 4a to 4h, and the 4-bit data of the outputs D8 to D11 is input to the select terminal of the decoder 3. You. After the serial data is input to the shift register 2, the serial data from the controller 1 is input to the decoder 3 as a set signal, as shown in FIG. In the present embodiment,
The decoder 3 does not output the latch signal when the set signal is set to "1", and is selected by the 4-bit parallel data of the outputs D8 to D11 only when the set signal is set to "0". First to eighth latch circuits 4
A latch signal is supplied to any one of the latch circuits a to 4h, for example, the first latch circuit 4a.

The first latch circuit 4a to which the latch signal is supplied latches 8-bit parallel data from the outputs D0 to D7, and the first D / A converter connected to the first latch circuit 4a. 8-bit parallel data is input to 5a, and the first D / A converter generates a 256-resolution analog voltage from the latched 8-bit parallel data.

If the parallel data input to the first D / A converter 5a differs before and after the first latch circuit 4a latches, as shown in FIG.
The control voltage Vcont changes, and therefore the output voltage Vhvl also changes according to equation (1).

The set signals input from the controller 1 to the decoder 3 are designed to sequentially designate different latch circuits. As shown in FIG. The 8-bit parallel data of D7 is input to the second latch circuit 4b and latched. If the parallel data input to the second D / A converter 5b is different before and after the latch by the second latch circuit 4b, As shown in FIG. 4 (g), the control voltage Vcont
And therefore, according to equation (1), the output voltage Vhv
l also changes.

Thus, the output voltage Vhvl of the D / A converter 5 can be changed at the timing when the latch circuit 4 selected by the decoder 3 performs the latch operation.

FIG. 5 is a time chart showing the relationship between the control voltage Vcont and the output voltage Vhvl on the time axis to which a number of latch signals are input.

That is, as shown in FIG.
On the time axis in which a large number of latch signals are input as shown in (d), the control voltage Vcont changes at the output timing of the latch signal. The output voltage Vhvl fluctuates in response to the fluctuation of the control voltage Vcont, as shown in Expression (1).
In the present embodiment, since the serial data is output from the controller 1 at a high frequency equal to or higher than the predetermined clock frequency, the transfer cycle of the serial data becomes sufficiently faster than the response time of the output voltage. Voltage V
The convergence time to reach hvlo is very long. Therefore, as shown in FIG. 5B, even when the noise signal N is superimposed on the control voltage Vcont, the output voltage Vhv
l does not respond immediately, and normal parallel data is D / A at the output timing of parallel data from the next latch circuit.
When the control voltage Vcont is input to the converter, the control voltage Vcont returns to the desired voltage, so that the output voltage Vhvl does not fluctuate greatly and the voltage fluctuation can be suppressed to such an extent that image formation is not affected. Since the response of the output voltage to the control signal is usually several tens to several hundreds of ms,
The predetermined clock frequency at which the serial data is transferred is given by Equation 1.
The effects of the present invention can be achieved at a high frequency of 0 kHz or more.

The present invention is not limited to the above embodiment. For example, in the present embodiment, the parallel data input to the D / A converter 5 is latched, but the control voltage Vcont output from the D / A converter 5 is latched.
May be latched in accordance with the selected high-voltage control circuit 6, and the same effect can be obtained even when a PWM circuit is used in place of the D / A converter 5.

[0042]

As described in detail above, according to the present invention, serial control data is generated, the generated serial control data is converted into parallel control data by data conversion means, and based on the parallel control data. Since the control voltage is generated, a high voltage is output based on the control voltage, and the serial control data is transferred to the data conversion means at a high frequency equal to or higher than a predetermined frequency.
A plurality of high-voltage outputs can be controlled by one serial data, and the transfer cycle of the serial data can be made sufficiently shorter than the response time of the output voltage. Therefore, even when the noise signal is superimposed on the control voltage, the control voltage can be returned to the desired voltage by supplying the normal serial data before the high voltage is output, and thereby the noise signal can be restored. It is possible to prevent malfunction due to

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a high-voltage output device according to the present invention.

FIG. 2 is an electric circuit diagram showing details of a high voltage generation circuit.

FIG. 3 is an electric circuit diagram showing details of a high-voltage control circuit.

FIG. 4 is a timing chart showing output timings of various signal outputs.

FIG. 5 is a timing chart showing a relationship between a control voltage and an output voltage on a long-time axis.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Controller (serial generation means) 2 Shift register (data conversion means) 3 Decoder (selection means) 6a-6h High voltage control circuit (high voltage control means) 7 High voltage generation circuit (high voltage generation means)

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H02M 7/48 H02M 7/48 T H03M 1/66 H03M 1/66 C 9/00 9/00 C F term (Ref.)

Claims (8)

[Claims] 1. Serial data generating means for generating serial control data, data converting means for converting serial control data generated by the serial data generating means into parallel control data, and high voltage generating means for generating high voltage A plurality of high voltage control means for controlling a high voltage from the high voltage generation means based on the parallel control data and outputting a predetermined control voltage, wherein the serial data generation means includes an output of the plurality of high voltage generation circuits. Data transfer means for generating values so that data is sequentially and repeatedly input periodically, and transferring the generated serial control data to the data conversion means at a high frequency equal to or higher than a predetermined frequency. A high-voltage output device comprising: 2. High-pressure control means for selecting one of the plurality of high-pressure control means from among the plurality of high-pressure control means, wherein the high-pressure control means selected by the selection means receives parallel control data from the data conversion means. The high-voltage output device according to claim 1, wherein the power is supplied. 3. The predetermined frequency is at least 10 KHz.
The high-voltage output device according to claim 1 or 2, wherein: 4. The high voltage output device according to claim 1, wherein said data conversion means is a shift register. 5. A serial data generating step for generating serial control data, a data converting step for converting the serial control data generated in the serial data generating step into parallel control data, and a high voltage generating step for generating a high voltage. A control voltage output step of controlling the high voltage based on the parallel control data and outputting a predetermined control voltage from the high voltage control means, further comprising the step of transmitting the serial control data generated in the serial data generation step to a predetermined frequency. Repeat periodically with the above high frequency. A high-voltage output control method, comprising a data transfer step of transferring the serial control data. 6. A high-pressure control unit having a plurality of said high-pressure control means,
6. The high-voltage control device according to claim 5, further comprising a step of selecting one of the plurality of high-voltage control means from the plurality of high-voltage control means, and supplying parallel control data to the selected high-voltage control means. Output control method. 7. The predetermined frequency is at least 10 KHz.
7. The high-voltage output control method according to claim 5, wherein: 8. An image forming apparatus comprising the high-voltage output device according to claim 1. Description: