JP2988640B2 - Image forming apparatus and transfer apparatus high-voltage control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using a transfer roller in an electrophotographic process and a method for controlling a high voltage of the transfer apparatus.

[0002]

2. Description of the Related Art Conventionally, control of a high-voltage power supply using a contact transfer method is performed with a basic configuration as shown in FIG.

In the electrophotographic process of this embodiment, a positive high voltage is applied to a transfer roller 2 serving as a transfer means adjacent to a drum-shaped photosensitive member 1 to transfer a toner image on the photosensitive drum 1 onto a transfer material 3. I do. Here, the toner image is formed by a well-known electrophotographic process including a primary charger 4, a developing unit 5, respective high-voltage power supplies 7, 6 and an exposure unit for forming an electrostatic latent image. The developing high voltage power supply 6 and the primary charging high voltage power supply 7 are controlled by control signals CONT3, COT
ON / OFF control is performed by NT4.

The high voltage applied to the transfer roller 2 is shown in FIG.
Are output from the inverter transformer 9 shown in FIG. The inverter transformer 9 receives the pulse signal OSC from the high-voltage controller 8.
Is driven through the transistor 10. The pulse signal is rectified on the secondary side of the inverter transformer 9 (diode 11, capacitor 12) and applied to the transfer roller 2. Here, the DC level of the transfer high voltage output is proportional to the emitter potential of the transistor 13 and is turned on / off via the transistor 14 by a control signal CONT2 from the voltage control unit 8.

FIG. 16 shows a high-pressure control sequence. When the system enters a printing operation and the photosensitive drum is driven, high-voltage output is performed for each of primary charging, development, and transfer by control signals CONT4, CONT3, and CONT2.

At the time of the pre-rotation and the paper interval, CONT1 is at "H" level and the analog switches 16a and 16c are
N and 16b are turned off and the constant current operation starts. At this time, the output of the operational amplifier 15 is input to the operational amplifier 17 through the analog switch 16a. Therefore, the output of the operational amplifier 15 determines the emitter potential of the transistor 13. Since the output of the inverter transformer 9 is determined by the emitter potential of the transistor 13, the output of the operational amplifier 15 determines the transfer output value. The output of the operational amplifier 15 is charged into the low-leakage capacitor 18 through the analog switch 16c, so that the output voltage during the constant current operation is equivalently stored. The current value It during the constant current operation is
It is determined by the divided voltage value of Vcc by the resistors 19 and 20 and the resistance value of the resistor 21. That is, in this example, It = Vcc · R20 / (R19 + R20) / R21.

At the time of printing, CONT1 is at the "L" level and the analog switches 16a and 16c are OFF and 16b
Turns ON and enters constant voltage operation. In the constant voltage operation, the potential charged in the low leakage capacitor 18 determines the emitter potential of the transistor 13 through the analog switch 16b.
The transfer output is determined by the potential charged in the transfer.

The output voltage of the transfer is as shown in FIG. During a constant current operation, the voltage fluctuates due to load fluctuation (resistance unevenness in the circumferential direction of the transfer roller). The output of the operational amplifier 15 is charged to the low-leakage capacitor 18 by averaging it with the time constant of the resistor 36 and the capacitor 18.

[0009]

However, in the above-mentioned prior art, the following problems have been encountered since the present invention relies on hardware using a capacitor as a means for storing an output voltage during a constant current operation.

(1) The circuit configuration is complicated.

(2) The capacitor current fluctuates due to the leak current, and the output voltage changes during the constant voltage operation.

(3) The constant current operation must be repeated for each print for item (2), which complicates the sequence.

The present invention has been made to solve the above-mentioned problems of the conventional example, and has a circuit configuration and a sequence.
And a stable transfer high voltage can be output.
The toner image on the image carrier is transferred to a transfer material using a transfer roller.
In the image forming apparatus copies, when setting the constant voltage to be supplied to the transfer unit at the time of image formation, it is an object that you as not receiving as much as possible the influence of the resistance-free et <br/> transfer roller .

[0014]

In order to achieve the above object, according to the present invention, an image forming apparatus includes the following (1) to (7).
And the high-pressure control method of the transfer device is as follows.
The configuration is as shown in (8) .

(1) Transfer roller for transferring toner image on image carrier
A transfer unit that transfers to a transfer material by using, to the transfer unit
Voltage control means for outputting a constant voltage, and output to the transfer means
And control means for outputting a voltage instruction value for instructing a constant voltage to said voltage control means is, before the said voltage control means
A first detecting means for detecting a current value output to the serial transfer means, and determination means for current value detected by said first detecting means determines whether or not reached a predetermined value, the determination
Determining means for determining a voltage indication value according to the determination result of the means, and a voltage indication value based on the voltage indication value determined by the determining means.
A second method for detecting a current value when a constant voltage is output to the transfer unit in a manner in which the rotation angle of the transfer roller is varied.
An image forming apparatus comprising: a detection unit; and a correction unit that performs an arithmetic process based on the current value detected by the second detection unit and corrects the voltage instruction value determined by the determination unit.

(2) The second detecting means includes a transfer row.
(1) detecting current values for a plurality of rotation angles
The image forming apparatus as described in the above.

(3) The second detecting means includes a transfer row.
The current value is detected multiple times during one rotation of the
The image forming apparatus according to (2).

(4) Voltage finger used for previous image formation
The voltage finger used for the second and subsequent image formation based on the indicated value
The image forming apparatus according to (1), wherein the reading value is determined.

(5) Voltage finger used for previous image formation
The value obtained by multiplying a predetermined value to示値 as the initial value, the second and subsequent
Having means for determining a voltage indication value used for image formation
The image forming apparatus according to the above (4).

(6) The control means converts the digital value to D / A
The above-mentioned (1), which is converted and input to the voltage control means.
Image forming apparatus.

(7) The control means outputs the pulse width modulated signal.
Filter processing and input to the voltage control means
The image forming apparatus according to (1).

(8) A transfer roller for transferring the toner image on the image carrier
A high voltage control method of a transfer apparatus for transferring a transfer material using a conductive for instructing a constant voltage output to the transfer device
And a control step of outputting the pressure command value, whether a first detection step of detecting a current value output to the transfer device, the current value Oite detected in the first detection step reaches a predetermined value a determination step of determining, a determination step of determining a voltage command value in accordance with the determination result of said determining step, determined the
A constant voltage based on the voltage instruction value was supplied to the transfer device.
The current value at the time, the rotation angle of the transfer roller was changed
A second detection step of detecting in an aspect, and the second detection step
Performing an arithmetic process based on the detected current value,
A high-voltage control method for a transfer device, the method including a correction step of correcting a voltage instruction value .

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

(Configuration) FIG. 1 shows a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a photosensitive drum which is a photosensitive member in an electrophotographic process, 2 denotes a transfer roller which is a transfer means in a contact transfer system, 3 denotes paper as a transfer material, 4 denotes a primary charger, and 5 denotes a primary charger. Is a developing device, 6 is a high voltage power source for developing,
Reference numeral 7 denotes a primary charging high-voltage power supply, and reference numeral 8 denotes a high-voltage control unit including a determination unit and a storage unit C. Circuits indicated by 9 and thereafter are transfer high-voltage power supplies constituting the voltage control means A and the output current detection means B.

In this embodiment, the drum-shaped photosensitive member 1
The toner image on the photosensitive drum 1 is transferred onto the transfer material 3 by applying a positive high voltage to the transfer roller 2 as transfer means adjacent to the transfer roller 3. Here, the toner image is formed by a well-known electrophotographic process including a primary charger 4, a developing unit 5, respective high-voltage power supplies 7, 6 and an exposure unit for forming an electrostatic latent image. The developing high voltage power supply 6 and the primary charging high voltage power supply 7 are turned on by the control signals CONT3 and CONT4 from the high voltage control unit 8.
N / OFF control is performed.

The high voltage applied to the transfer roller 2 is output from an inverter transformer 9 constituting the voltage control means A shown in FIG. The inverter transformer 9 includes the high-voltage control unit 8
Is driven via the transistor 10 by the pulse signal OSC from The pulse signal is rectified on the secondary side of the inverter transformer 9 (the diode 11 and the capacitor 1).
2) applied to the transfer roller 2;

Here, the DC level of the transfer high voltage output is proportional to the emitter potential of the transistor 13. The output HVTIN1 (DC level signal) from the high voltage control unit 8 is:
The transistor 13 amplified in the operational amplifier 100
Is entered at the base of Therefore, the transfer output voltage increases with an increase in HVTIN1. The output current at this time can be detected by referring to the voltage drop of the resistor 102 by the operational amplifier 101 constituting the output current detecting means B.
The high-voltage control unit 8 outputs the output of the operational amplifier 101 (HVTOU
From T1), the output current It can be calculated as It = (5-HVTOUT1) / R102.

In the high-voltage control unit 8, HVTIN1 is set to D
The / A output signal and HVTOUT1 are A / D input signals.

(Operation) An operation will be described based on the above configuration.

FIGS. 2 to 5 are flow charts showing the high-pressure control sequence and the functions of the judgment means and storage means C constituting the high-pressure control unit 8 in this embodiment. In the figure, SO to S29 represent each step of the flowchart.

First, the first printing operation after the power is turned on is set to S0.
To S5.

The system enters a printing operation, drives the photosensitive drum in S0, starts a timer in S1, sets an initial value in S2, and outputs primary charging and developing high voltage by control signals CONT4 and CONT3 in S3.

In S4, HVTIN1 is incremented by one bit, and in S5, it is determined whether HVTOUT1 has reached a target current value K. If HVTOUT1 is larger than K, it is determined that the current value has not reached the target current value, and the process returns to S4 and H
The operation of increasing VTIN1 by 1 bit is repeated. HVTO
If UT1 is equal to or less than K, it is determined that the target current value has been reached, and the time of the timer is stored (TA = t) in S6. In steps S7 and S8, the input HVTOUT1 to the A / D of the high-voltage controller 8 is sampled during the time t1 for one rotation of the transfer roller, and the total TOTAL is obtained. At this time, the transfer high voltage output is in a constant voltage operation state at HVTIN1.

After a lapse of t1 from the time TA, at step S9, the HVTI
A desired constant voltage output value CV is obtained from N1, the target value K, the total TOTAL of the output current, and the number of samples N as follows.

CV = HVTIN1 · (5-K) / (5-TOTAL / N) This calculates the output voltage value obtained from the difference between the average output current and the target constant current output value K.

When the time t2 at which the printing operation starts in S10 (t ≧ t2), the desired constant voltage operation corrected in S11 starts (HVTIN1 is fixed to the obtained value CV). Also, the time (t2-t1) until the printing operation starts.
-TA), the transfer output may be turned off (HVTIN1 = 0).

During continuous printing, HVTIN1
Is set to “0”, and the constant voltage value obtained earlier is output (HVTIN1 = CV) at the timing of starting printing.

After printing is completed in S12, CONT is performed in S13.
3, after turning off CONT4 and HVTIN1, and after the post-rotation processing, the drive of the photosensitive drum 1 is stopped in S14, and the timer is reset in S15.

Next, the printing operation from the second and subsequent pre-rotations is shown in S16 to S29 of FIG.

First, a drum start is set in S16, a timer is started in S17, an initial value is set in S18, and C is set in S19.
ONT3 and CONT4 are turned on to output a developing high voltage and a primary charging high voltage power supply.

Subsequently, in step S20, HVTIN1 is set as the output voltage value CV obtained in the previous printing operation, and the operation enters the constant voltage output operation. In steps S21 and S22, the input HVTIN1 to the A / D of the high-voltage controller 8 is sampled during the time t1 for one rotation of the transfer roller, and the total TOTAL is obtained. After a lapse of t1 from the start of the timer in S17, HVTIN1 and the target value K, the total TOTAL of the output current,
A desired constant voltage output value CV is obtained from the number N of samples (S
9).

Thereafter, at time t2 when the printing operation is started at S24, the desired constant voltage operation corrected at S25 is started (HVTIN1 is fixed to the obtained value CV). Also,
Time (t2-t) before starting the printing operation in S24
In 1), the transfer output may be turned off (HVTIN1 = 0).

At the time of continuous printing, HVTIN1
Is set to “0”, and the constant voltage value obtained earlier is output (HVTIN1 = CV) at the timing of starting printing.

After printing is completed in S26, CONT is performed in S27.
3, after turning off CONT4 and HVTIN1, and after the post-rotation processing, the drive of the photosensitive drum 1 is stopped in S28, and the timer is reset in S29.

In this embodiment, HVTIN1 is used as the D / A output signal from the high voltage controller 8, but it is also possible to adopt a configuration in which the PWM signal passes through a low-pass filter.

Next, a second embodiment will be described with reference to the drawings.

FIGS. 6 to 9 are flow charts showing the high-pressure control sequence and the functions of the judgment means and storage means C constituting the high-pressure control unit 8 in the second embodiment. In the drawing, S0 to S29 represent each step of the flowchart.

The hardware configuration of the second embodiment is the same as that of the first embodiment, and a description thereof will be omitted.

The first printing operation after power-on (S0 to S1)
5) is the same as in the first embodiment, and a description thereof will not be repeated.

The printing operation from the pre-rotation for the second and subsequent times is S
16 to S29.

First, a drum start is set in S16, a timer is started in S17, an initial value is set in S18, and C is set in S19.
ONT3 and CONT4 are turned on to output a developing high voltage and a primary charging high voltage power supply.

At S20-1, the constant voltage output operation is started with HVTIN1 as the output voltage value CV · 0.8 obtained in the previous print operation. In steps S21 and S22, the input HVTOUT1 to the A / D of the high-voltage controller 8 is sampled during the time t1 for one rotation of the transfer roller, and the total TOTAL thereof is sampled.
Take. After t1 has elapsed from the start of the timer in S16, S2
3, HVTIN1 and target value K, total TOTA of output current
A desired constant voltage output value CV is obtained from L and the number of samples N as follows.

CV = HVTIN1 · (5-K) / (5-TOTAL / N) Then, at time t2 when the printing operation starts in S24, the desired constant voltage operation corrected in S25 starts (HVTI).
N1 is fixed to the obtained value CV). In addition, the transfer output may be turned off (HVTIN1 = 0) during the time (t2-t1) before the printing operation in S24.

During continuous printing, HVTIN1
Is set to “0”, and the constant voltage value obtained earlier is output (HVTIN1 = CV) at the timing of starting printing.

After printing is completed in S26, CONT is performed in S27.
3, after turning off CONT4 and HVTIN1, and after the post-rotation processing, the driving of the photosensitive drum 1 is stopped in S28, and the timer is reset in S29.

This embodiment is effective for preventing excessive output from being applied to the transfer roller and the photosensitive drum when the load condition of the high-voltage power supply changes due to environmental changes (temperature, humidity) around the transfer roller during standby. .

In this embodiment, HVT is selected in S20-1.
IN = CV · 0.8. However, as long as the error due to the linearity of the circuit system and the accuracy of the A / D converter input to the HVTOUT1 is within an allowable range for the system, the number may be multiplied (it does not need to be 0.8).

Although HVTIN1 is used as the D / A output signal from the high voltage controller 8, it is also possible to adopt a configuration in which the PWM signal passes through a low-pass filter.

Next, a third embodiment will be described with reference to the drawings.

FIGS. 10 to 14 are flowcharts showing the high-voltage control sequence and the functions of the judgment means and the storage means constituting the high-pressure control unit 8 in the third embodiment. In the figure, S0 to S53 represent each step of the flowchart.

Since the hardware configuration in the third embodiment is the same as that in the first embodiment, the description is omitted.

The system enters a printing operation, drives the photosensitive drum in S0, starts a timer in S1, sets an initial value in S2, and outputs primary charging and developing high voltage by control signals CONT4 and CONT3 in S3.

At S4, HVTIN1 is incremented by one bit, and at S5, it is determined whether HVTOUT1 has reached the target current value K. If HVTOUT1 is equal to or larger than K, it is determined that the current value has not reached the target value, and the operation of increasing HVTIN1 by 1 bit is repeated. If HVTOUT1 is equal to or smaller than K, it is determined that the target current value has been reached, and S6
Stores the time of the timer (TA = t).

In steps S31 to S34, the constant current operation is performed at the target value K, and the total TOTAL of the output HVTIN1 at that time is set for the time t1 for one rotation of the transfer roller. Then, as a result, an average output voltage during the constant current operation is obtained in S36.

Thereafter, until the printing operation is started (t ≧ t
2) The output HVTIN1 is set to “0” in S37, and S11,
The printing operation is started in S12 and the constant voltage operation based on the voltage obtained in S36 is started (the value CV obtained by calculating HVTIN1).
Fixed to).

During continuous printing, HVTIN1
Is set to “0”, and the constant voltage value obtained earlier is output (HVTIN1 = CV) at the timing of starting printing.

After the printing is completed, at S13, CONT3, CO
NT4 is turned off, and after the post-rotation processing, the drive of the photosensitive drum 1 is stopped in S14, and the timer is reset in S15.

Next, the printing operation from the second or subsequent pre-rotation is shown in S16 to S53 of FIGS.

First, a drum start is set in S16, a timer is started in S17, an initial value is set in S18, and C is set in S19.
ONT3 and CONT4 are turned on to output a developing high voltage and a primary charging high voltage power supply.

In S41, HVTON1 is set as the output voltage value CV obtained in the previous printing operation.
In step 5, the output HVTIN1 is incremented or decremented until the target current value is reached. When the output current reaches the target value, the time of the timer is stored in S46.

Then, in S47 to S51, the D / D of the high voltage controller 8 during the constant current operation is performed during the time t1 for one rotation of the transfer roller.
Take the total TOTAL of the output HVTON1 from A
At 52, the average output voltage is determined.

Thereafter, until the printing operation is started (t ≧ t
2) The output HVTIN1 is set to “0” in S53, and S25,
At S26, the printing operation is started, and at the same time, the constant voltage operation based on the voltage obtained at S52 is started (HVTIN1 is fixed at the obtained value CV).

During continuous printing, HVTIN1
Is set to “0”, and the constant voltage value obtained earlier is output (HVTIN1 = CV) at the timing of starting printing.

After printing is completed, in S27, CONT3, CO
NT4 and HVTIN1 are turned off, and after the post-rotation processing, S
At 28, the driving of the photosensitive drum 1 is stopped, and at S29, the timer is reset.

In this embodiment, analog detection (HVTO) by an operational amplifier (101 in FIG. 1) is used as output current detection means.
Although UT1) was performed, digital detection means using a comparator can be used.

Although HVTIN1 is used as the D / A output signal from the high voltage control section 8, it is also possible to adopt a configuration in which the PWM signal passes through a low-pass filter.

[0078]

As described above, according to the present invention, the circuit configuration and the sequence can be simplified and stable.
Output high transfer pressure, and at the same time, the toner image on the image carrier
An image forming apparatus that uses a transfer roller to transfer to a transfer material
And set a constant voltage to be supplied to the transfer means during image formation.
The transfer roller to avoid the effects of uneven transfer resistance.
Can be done.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a first embodiment.

FIG. 2 is a high-pressure control sequence according to the first embodiment.

FIG. 3 is a flowchart (1) of the first embodiment.

FIG. 4 is a flowchart (2) of the first embodiment.

FIG. 5 is a flowchart (3) of the first embodiment.

FIG. 6 shows a high-pressure control sequence according to the second embodiment.

FIG. 7 is a flowchart (1) of the second embodiment.

FIG. 8 is a flowchart (2) of the second embodiment.

FIG. 9 is a flowchart (3) of the second embodiment.

FIG. 10 is a high-pressure control sequence according to the third embodiment.

FIG. 11 is a flowchart (1) of the third embodiment.

FIG. 12 is a flowchart (2) of the third embodiment.

FIG. 13 is a flowchart (3) of the third embodiment.

FIG. 14 is a flowchart (4) of the third embodiment.

FIG. 15 is a configuration diagram of a conventional example.

FIG. 16 shows a conventional high-pressure control sequence.

[Explanation of symbols]

 A voltage control means B output current detection means C determination means, storage means

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Shinpei Matsuo 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Yoji Serizawa 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inside (72) Inventor Shoji Uchiyama 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Kazuro Yamada 3-30-2, Shimomaruko, Ota-ku, Tokyo Canon Inc. (56) References JP-A-2-212872 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G03G 15/16

Claims (8)

(57) [Claims] And a transfer roller for transferring the toner image on the image carrier .
Transfer means for transferring to a transfer material, a voltage control means for outputting a constant voltage to the transfer means, and a voltage for instructing a constant voltage to be output to the transfer means.
And control means for outputting a command value to the voltage control means, the first detecting means, a current value detected by said first detection means predetermined for detecting a current value output from the voltage control means to said transferring means Determining means for determining whether or not the voltage value has been reached; determining means for determining a voltage instruction value according to the determination result of the determining means; and a constant voltage based on the voltage instruction value determined by the determining means.
The current value when the pressure is output to the transfer
Second detection that detects the rotation angle of the roller differently
Means based on the current value detected by the second detecting means.
Arithmetic processing, the voltage determined by the determination means
An image forming apparatus, comprising: a correction unit configured to correct an instruction value . 2. The image forming apparatus according to claim 1 , wherein said second detecting means is provided with a
It is characterized by detecting a current value for a plurality of rotation angles.
The image forming apparatus according to claim 1. 3. The image forming apparatus according to claim 2, wherein the second detecting means includes:
It is characterized by detecting the current value multiple times during one rotation
The image forming apparatus according to claim 2. 4. A voltage indicating value used in a previous image forming operation.
Voltage indication value used for the second and subsequent image formation based on
2. The image forming apparatus according to claim 1, wherein
Place. 5. A voltage indicating value used in a previous image forming operation.
Is multiplied by a predetermined value as the initial value.
Provision of means for determining a voltage indication value used for image formation
The image forming apparatus according to claim 4, wherein: 6. The control means performs D / A conversion of a digital value.
Processing and input to said voltage control means.
The image forming apparatus according to claim 1. 7. The control means according to claim 1, wherein the pulse width modulation signal is
Filter processing and input to the voltage control means.
The image forming apparatus according to claim 1. 8. A transfer roller for transferring a toner image on an image carrier .
A high-voltage control method of a transfer device for transferring to a transfer material, wherein a voltage instruction for instructing a constant voltage output to the transfer device is provided.
Determining a control step of outputting a value, the first detection step of detecting a current value output to the transfer device, whether the current value Oite detected in the first detection step reaches a predetermined value A determining step of determining the voltage instruction value according to the determination result of the determining step; and a constant voltage based on the determined voltage instruction value.
The current value when supplied to the transfer roller is determined by the rotation angle of the transfer roller.
A second detecting step of detecting in a different manner, and a current value detected in the second detecting step.
A high-voltage control method for a transfer device , comprising a correction step of performing an arithmetic process to correct the voltage instruction value .