JPH05265306A - Corona discharge device - Google Patents

Abstract

PURPOSE:To shorten the adjusting time of the distance of a photosensitive body and a corona discharger and the down time of an image forming device by easily executing the adjusting work of the distance of the photosensitive body and the corona discharger. CONSTITUTION:Discharging from a corona discharge electrode 41 to the photosensitive body 1 is interrupted by the fitting of a mask (shunt means) 50, except one end part in the longitudinal direction of the corona discharger, and a discharge current flowing in the photosensitive body 1 at this time, (which is in proportion to the distance of one end part of the corona discharger 41 and the photosensitive body 1), can be detected by a photosensitive body current detecting circuit 2. On the other hand, when the mask 50 is reversely fitted, the discharging from the corona discharge electrode 41 to the photosensitive body 1 is interrupted, except the other end part in the longitudinal direction of the corona discharger, and the discharge current flowing in the photosensitive body 1 at this time, (which is in proportion to the distance of the other end part and the photosensitive body 1), can be detected by the photosensitive body current detecting circuit 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a corona discharge device used in an image forming apparatus such as a copying machine.

[0002]

2. Description of the Related Art Generally, in an image forming apparatus such as a copying machine, a drum-shaped or belt-shaped photosensitive member and several corona dischargers are arranged around the photosensitive member in the image forming section. A discharge is generated between the photoconductor and a current is passed to charge and remove the photoconductor. Since the charge amount of the photoconductor has a great influence on the formed image, it is necessary to accurately control the charge amount and the like in order to realize good image formation.

By the way, this type of corona discharger, when used for a long period of time, adsorbs toner, paper powder, and dust in the air to become dirty. Since this kind of dirt adversely affects the discharge state, periodical cleaning and maintenance work such as replacement of the corona discharger are required. When the corona discharger is replaced, the distance between the electrode of the corona discharger (wire having a pole of about 80 μm) and the photoconductor changes. Therefore, in order to obtain a uniform density image, The distance between the wire and the photosensitive member (L1, L2 in FIG. 4a) must be adjusted.

In this kind of adjustment work, conventionally, the photoconductor is first removed from the image forming apparatus, a pseudo photoconductor (jig drum) is incorporated in place of the photoconductor, and a charging current is applied at both ends in the axial direction of the photoconductor. While alternately measuring, the adjustment screw provided on the front side of the corona discharger was turned to adjust so that the charging currents at both ends were equal, and then the pseudo photoconductor was removed and the photoconductor was attached instead. ..

[0005]

However, the conventional work for adjusting the distance between the photoconductor and the corona discharger is very troublesome, and the image forming apparatus cannot be used during the work. It was

The present invention has been made in view of the above points, and by further simplifying the work of adjusting the distance between the photoconductor and the corona discharger, the time required for the work of adjustment is shortened, and the image forming apparatus. The goal is to reduce downtime.

[0007]

In order to achieve the above-mentioned object, the present invention comprises a corona discharger arranged facing a photoconductor of an image forming apparatus, and a power supply for supplying a high voltage to the corona discharger. In a corona discharge device provided with a control means for controlling the power supply to adjust a discharge current, a current detecting means for detecting a current flowing through the photoconductor and a part of the discharge current flowing to the photoconductor side are cut off, The flow dividing means is provided to bypass the detecting means.

Further, it is desirable to provide information output means for outputting information corresponding to the inclination of the corona discharger with respect to the photoconductor, based on the current detected by the current detection means. Further, it is preferable that the corona discharger is provided with a holding means to which the flow dividing means can be attached and detached. Along with this, it is desirable that the flow dividing means be configured by a mask that blocks the discharge from the corona discharger to the photoconductor except for one end portion in the longitudinal direction of the corona discharger. Furthermore, it is preferable that a part of the bypass route formed by the flow dividing means is formed by the shield electrode of the corona discharger.

Further, rotation adjusting means for adjusting the inclination of the corona discharge electrode of the corona discharger is provided, and the flow dividing means is detachable from the corona discharger and one of the openings facing the photoconductor of the corona discharger. The information output unit is configured to output a value calculated based on the difference between the electric currents detected at both axial ends of the photoconductor in association with the rotation amount of the rotation adjusting unit. It is desirable to configure

[0010]

In the corona discharge device according to the present invention, a part of the discharge current flowing to the photosensitive member side is cut off by the shunting means, and the cut off discharge current is caused to flow bypassing the current detecting means. For example, except for one end in the longitudinal direction of the corona discharger, the discharge from the corona discharger to the photoconductor is interrupted, and the discharge current flowing in the photoconductor at that time (the size is proportional to the distance between the one end and the photoconductor) Detect).

Next, except for the other longitudinal end of the corona discharger, the discharge from the corona discharger to the photoconductor is interrupted, and at that time, the discharge current flowing to the photoconductor (the size of the other end is different from that of the photoconductor). (Proportional to the distance of). Therefore, since the inclination adjustment of the corona discharger may be performed so that the respective current values are equal, the time required for the adjustment work is shortened and the downtime of the image forming apparatus is reduced accordingly.

By using the inventions of claims 2 to 6, it is possible to provide a more effective corona discharge device.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 1 shows the construction of an image forming unit for a copying machine embodying the present invention and a high-voltage power supply device for corona discharge connected thereto. This will be described with reference to FIG. The drum-shaped photoconductor 1 provided in the image forming unit rotates in the direction indicated by an arrow O in the figure. The photoconductor 1 is grounded via a photoconductor current detection circuit (hereinafter referred to as Id detection circuit) 2.

Around the photosensitive member 1, a charging corona discharger 4 connected to a charging high-voltage power supply (hereinafter referred to as C power supply) 3, a developing sleeve 6a connected to a developing bias power supply (hereinafter referred to as B power supply) 5. Including a developing device 6, pre-transfer static elimination high-voltage power supply (hereinafter referred to as PT transformer) 7, PT corona discharger 8, transfer high-voltage power supply (hereinafter referred to as T power supply) 9, transfer corona discharger 10, Separated corona discharger 1 connected to separated high-voltage power supply (hereinafter referred to as D transformer) 11.
2, a cleaning device 1 including a PC corona discharger 14 connected to a high voltage power supply (hereinafter referred to as a PC transformer) 13 for pre-cleaning static electricity removal, and a bias roller 16a connected to a cleaning bias power supply (hereinafter referred to as a BR power supply) 15
6, and static elimination high-voltage power supply (hereinafter referred to as PQ transformer) 17
A static elimination corona discharger 18 connected to the is provided.

Further, between the PT corona discharger 8 and the transfer corona discharger 10, a guide plate and a feed roller 19 in the path of transfer paper are transferred, and on the downstream side of the separation corona discharger 12, an image is transferred. A transfer device 20 is provided for sending the transferred transfer paper to a fixing device (not shown) in the next step.

A control circuit (CP
U) 30 is connected with PWM (pulse width modulation) timers 31, 32 and 34 via a bus line 21. The PWM timer 31 is connected to five power sources 3, 5, 9, 15, 17 that output a high DC voltage. The PWM timer 32 is connected to the AC component drive circuit 33, and the PWM timer 34 is connected to the DC component drive circuit 35.

To the power supplies 7, 11, and 13, a voltage in which the alternating current output by the alternating current drive circuit 33 and the direct current output by the direct current drive circuit 35 are superimposed is applied. An oscillator circuit 36 and an output detection circuit 37 are connected to the power supplies 7, 11, and 13, respectively. The control circuit 30 is connected via a serial data communication circuit to a main controller (not shown) that controls the operation of the entire copying machine.

Next, the image forming process by the copying machine of FIG. 2 will be briefly described. The photoreceptor 1 containing selenium as a main component is charged to a positive high potential (about 800 V) by corona discharge by the charging corona discharger 4. The reflected light obtained by exposing the original image is formed on the charged surface, and thereby a potential distribution corresponding to the intensity distribution of the reflected light, that is, an electrostatic latent image is formed.

Further, the electrostatic latent image is visualized by adhering toner on the developing sleeve 6 provided in the developing device 6 according to the potential thereof, and a toner image is formed on the surface of the photoconductor 1. It Then, the electrostatic attraction force between the toner and the photoconductor 1 is weakened by the AC corona discharge by the PT corona discharger 8.

On the other hand, the transfer sheet is sent out by the feed roller 19 in time with the image forming timing, and is superposed on the toner image formed on the photoconductor 1. Next, an electric field having a polarity opposite to the charge (negative polarity) of the toner is applied from the back surface of the transfer paper by the transfer corona discharger 10, and the toner image on the photoconductor 1 is transferred to the transfer paper.

Since this transfer paper is attracted to the photoconductor 1 by the electric field in the transfer step, an AC electric field is applied from the back surface of the transfer paper by the separating corona discharger 12 to eliminate the electric charge of the transfer paper. As a result, the transfer paper on which the toner image is transferred is separated from the photoconductor 1 by its own weight and moves toward the transport device 20.

Since paper dust and a small amount of toner that has not been transferred adhere to the photoreceptor 1 after separation, an AC electric field is applied by the PC corona discharger 14 to make the potential uniform, and then cleaning is performed. The fur brush 16b in the device 16 removes the residual toner from the photoconductor 1. The toner attached to the fur brush 16b is removed by the bias roller 16a and is collected in a waste toner tank (not shown).

Next, the photoconductor 1 is neutralized by a DC electric field by the PC corona discharger 18, and then photo-erased by the static elimination lamp 22 to return to the initial state, and one cycle of a series of image forming processes is completed. ..

Next, the contents of the copying process by the main control unit (not shown) will be described with reference to the flowchart of FIG. When the power is turned on, the CPU is first initialized, and then each unit of the copying machine is set to the initial state. This initial setting includes initial setting of the discharge current (photoconductor charging current) of each corona discharger of the image forming unit.

Next, it is judged whether or not the SP mode for service maintenance is selected, and if it is not selected, the SP mode processing is executed as it is, and if it is selected, the standby mode processing is executed. To do. This processing includes display processing of the operation unit of the copying machine, reading of the state of each key and processing corresponding to the result, reading of each sensor output, and determination of abnormality.

After the parts of the copying machine are ready and ready for copying, the standby mode process is repeated until the operator presses the print key. When the print key is pressed, Perform the pre-copy mode processing. Here, the process of feeding the transfer paper to the image forming unit is performed.

Next, a copy mode process is executed. In this process, each corona discharger is turned on / off at a predetermined timing according to the sizes of the original and the transfer paper, control of other parts involved in the copying process, transfer paper transfer processing, and the like are performed. When making multiple copies, this mode is repeated until the number of repeats is reached.

Next, the post-copy mode processing is executed.
Here, the discharge processing of the transfer sheet and the setting of the discharge current of the corona discharger for the next copy are performed. When this process ends, the process returns to the above-mentioned standby mode process, and this mode is repeated until the print key is pressed again.

As described above, when the post-copy mode is executed,
Since the discharge current of the corona discharger is set (photoconductor charging current setting mode, which will be described later), while the operator is taking out the copied transfer paper or original, the discharge current setting is completed and Can be prepared for a copy of.

During execution of the photoconductor charging current setting mode, in order to make the induced current from the developing device or cleaning device in contact with the photoconductor constant, the developing sleeve and bias disposed in these devices are set. The bias voltage supplied to the roller is always maintained at a constant value.

Next, the contents of software processing relating to the high voltage generating section by the control circuit 30 of FIG. 2 will be described with reference to the flowchart of FIG. When the power is turned on,
Perform initial settings. In this initial setting, the count value of the PWM timer 31 shown in FIG. 2 and the immediately preceding values such as the target value in the constant current control and the photoconductor charging current setting mode are read from the backup memory of the main control unit and the control circuit 30 Is set to.

Further, from the output detection circuit 37 to the control circuit 3
The signal to be taken into 0 is selected, and the FB interrupt timer which sets the timing of the processing is started. Therefore, when the trigger of the power supply and the transformer is turned on after this setting is completed, the corresponding high voltage output is supplied to the corona discharger.

Next, the FR adjustment mode, the photoconductor charging current setting mode, the image forming mode, and the output abnormality process are repeatedly processed in a loop. These modes are executed as needed in response to an interrupt signal from the main controller.
Normally, after the photoconductor charging current setting mode process is executed when the power of the copying machine is turned on, when the print key is pressed, the image forming mode process is executed in coordination with the copy mode process of the main controller. In the post-copying mode processing, the processing of the photoconductor charging current setting mode is executed. Therefore, after the power is turned on, the process of the photoconductor charging current setting mode is executed for each copy by pressing the print key.

Next, the SP mode will be described. Although many functions for maintenance are provided in this mode, only the FR adjustment mode according to the present invention will be described here. For example, when the corona discharge electrode of the corona discharger is replaced, if there is an inclination between the electrode and the photoconductor 1, the image density becomes uneven. In order to eliminate this unevenness in image density (density difference between the front side F and the rear side R of the corona discharger), the FR adjustment mode is used.

In this adjustment, as shown in FIG.
Distance L1 on the front side of the corona discharge electrode 41 with respect to the photoconductor 1
The inclination is corrected by adjusting the distance L2 on the rear side and the distance L2 on the rear side.
As for the corona discharge electrode 41, as shown in FIG. 8, the height can be adjusted only on the front side F by rotating the adjusting screw 42. Therefore, the inclination can be corrected by rotating the adjusting screw 42.

Now, the processing of the SP mode by the control circuit 30 of FIG. 2 will be described with reference to FIG. This SP
The mode is designated by switching a dip switch (not shown) mounted on the apparatus body. After entering the SP mode, a mode for maintenance is selected by a key operation on the operation panel (not shown). If an instruction to select the FR adjustment mode is given here, first, on the operation panel. "Instruction to attach the front side of the mask (flow dividing means)" is displayed.

Then, the operator follows the display and
The mask 50 as shown in FIG. 3 is attached to the shield electrode (case) 43 of the corona discharger so that the cutout hole 50a is on the front side (F side). The shield electrode is
A slide portion 43a (holding means) for holding the mask 50 is formed, and the mask 50 is fitted and attached to this portion.

The mask 50 is molded of plastic (insulator), and a conductive electrode (hereinafter referred to as a pattern) 51 is provided on the surface facing the corona discharge electrode 41. The mask 50 has a detachable shape with respect to the corona discharger. By mounting this, the opening (the portion facing the photoconductor) of the corona discharger (shield electrode 43) is masked except for the portion of the cutout hole 50a, and the pattern 51 is the shield electrode of the corona discharger. 43
And is electrically connected to earth.

When the mask 50 is mounted on the corona discharger, the pattern 51 has a shape in which the current flowing to the photosensitive member 1 side is at the same level as when the mask 50 is not provided, and the state of corona discharge and the current distribution are similar. Is set. More specifically, the photoconductor 1 has a cylindrical shape, and the photoconductor 1 has an arcuate shape when viewed from the corona discharger disposed outside thereof. On the other hand, mask 5
Reference numeral 0 is a flat plate, and the distance from the corona discharge electrode 41 is shorter than that from the photoconductor.

Therefore, if the pattern 51 is uniformly provided on the mask 50, the actual discharge state will be greatly different. Therefore, while making the pattern 51 into a ladder shape,
The central portion near the corona discharge electrode 41 has a wide width.
Further, since the notch hole 50a is formed at one end of the mask 50, only one end or the other end of the corona discharger is opened to the photoconductor 1 depending on the mounting direction of the mask 50.

When the print key on the operation panel is pressed, the FR adjustment mode start flag is transmitted as an interrupt to the control circuit 30 of the high voltage generator. As a result, the control circuit 30 of the high voltage generator executes the FR adjustment subroutine as shown in FIG. 13, so that a predetermined high voltage is applied to the electrode 41 of the corona discharger, and the corona discharge is applied to the photoconductor 1 by the corona discharge. An electric current flows.

However, since the mask 50 is attached to the corona discharger and the cutout hole 50a is located on the front side (F side) at this time, only the position of the cutout hole 50a as shown in FIG. A corona discharge current (FId) flows through the. Further, the corona discharge current (Id-FId) at the portion blocked by the mask 50 is shunted by the conductive pattern 51 on the mask 50, and the shield electrode 43 of the corona discharger is formed.
The corona discharge current (Id-FId) in the part of which the ground (housing) is cut off via the shunt is shunted by the conductive pattern 51 on the mask 50, and the shield electrode 4 of the corona discharger is provided.
Through 3 to the ground (housing).

As a result, the shunted current bypasses the Id detection circuit 2 and the corona discharge current Ic to the shield electrode 43.
It flows to the ground with. On the other hand, since the current flowing to the photoconductor 1 is detected by the Id detection circuit 2, the control circuit 30
Takes in the form of digital data by the built-in A / D converter and sends the information to the main controller.

Next, the control circuit 30 displays the "instruction to attach the rear side of the mask" on the display section on the operation panel.
According to the display, the operator reverses the direction of the mask 50 and mounts it on the corona discharger so that the cutout hole 50a is on the rear side (R side). Then, when the print key on the operation panel is pressed again, a predetermined high voltage is applied to the electrode 41 of the corona discharger as in the above case, and a corona discharge current flows through the photoconductor 1 by corona discharge.

In this case, the notch hole 50a is on the rear side (R side).
Since the mask 50 is attached to the corona discharger so as to be located at the position shown in FIG.
As shown in (C) of FIG.
d) flows. Since this current is detected by the Id detection circuit 2, the control circuit 30 captures it in the form of digital data by the built-in A / D converter and transmits this information to the main control device.

Also in this case, as in the case of FIG. 1B, a part of the current (Id) flowing to the photosensitive member 1 side is shunted by the conductive pattern 51 and flows to the ground. In the subsequent processing step, the detected front side current value FId and the rear side current value R are detected.
The front-rear difference ΔId is calculated as the difference from Id, and in the next processing step, the rotation amount N of the adjusting screw 42 required to make the front-rear difference ΔId zero is calculated. This processing is executed by the calculation of the following equation.

N = ΔId / Ids where Ids:
Amount of change in Id per rotation of AS The result of this calculation, that is, the value of N is displayed on the display unit on the operation panel. In this display, in addition to the numerical value, a + or-symbol depending on the polarity of N is also included. Therefore, when the operator rotates the adjusting screw 42 according to the displayed numerical value, the inclination between the discharge electrode 41 and the photosensitive member 1 is corrected,
The current unevenness (ΔId) becomes zero.

Next, another example of the mask will be described with reference to FIGS. The mask 52 shown in FIG. 9 is made of a conductor (for example, metal such as stainless steel) whose material is different from that of the above-mentioned example of FIG. 7, and is coated with an insulating material except for the conductive pattern 52a portion for shunting the corona discharge current. There is. The coating may be screen-printed or a plastic film (eg mylar sheet) may be applied. This conductor mask has the advantages of high strength and high dimensional accuracy.

The mask 53 shown in FIG. 10 is formed of an insulating material, and a plurality of conductive patterns 54a, 54b, 54 are formed on the mask 53 so as to be parallel to the corona discharge electrode 41.
c, 54d are formed, and print resistors 55a, 55b, 55c are provided between each pattern and the ground.

In this example, the resistance value of each printing resistor is set so that an appropriate corona discharge current flows through each conductive pattern. Therefore, the print resistance 55b connected to the pattern 54b in the central portion where a large amount of current flows has the lowest resistance value. By setting this resistance value, an arbitrary current can be passed through each pattern. In this example, the printing resistor is used as the resistor for setting the current, but a chip resistor or a normal resistor may be used without any problem. In addition to a resistor, a constant voltage element, a capacitor, or the like may be connected to make the current characteristic non-linear.

In the mask 56 shown in FIG. 11, the connection of the conductive pattern 57 to the ground is different from the above-described embodiments, and is not connected to the ground when the mask 56 is attached to the corona discharger. The pattern 57 on the mask 56 is connected to the shunt terminal 58, and is connected to the ground through a wire or the like outside the mask 56. An ammeter or the like may be connected instead of this electric wire.

Next, the power supply and transformer of the high-voltage power supply device shown in FIG. 2 will be described. C power source 3, T power source 9, P
The Q power supply 17 is a high-voltage power supply that outputs a direct current (about 6000 V) for corona discharge, and the output current is constant current controlled.
Each of the power supplies 3, 9 and 17 has the same circuit configuration, so one circuit among them will be described with reference to FIG. As shown in the figure, the power supply itself has a function of stabilizing the output.

As shown in FIG. 13, the DC high-voltage timer 31 applies to the power supply circuit a PWM signal whose cycle is T1 (for example, 1 KHz) and whose pulse width T2 changes. D / A converter 6
Reference numeral 1 denotes an integrating circuit, which integrates (smooths) the input PWM signal to generate an analog signal whose level changes in accordance with the pulse width of the PWM signal. This analog signal is output to the reference voltage terminal of the comparator 62.

The comparator 62 receives the voltage level of the analog signal and the feedback signal Es from the output detection circuit 63.
Voltage level of the pulse width modulation circuit (PWM circuit) 6
Output to 4.

The pulse width modulation circuit 64 outputs a pulse signal having a time width corresponding to the input error signal to the transistor Q.
1 and the transistor Q1 is turned on / off to switch the current in the primary winding of the high voltage transformer HVT1. Therefore, the switching duty of Q1 corresponds to the error signal, and a high voltage corresponding to the error signal is generated in the secondary winding of the high voltage transformer HVT1 (see FIG. 1).
4).

This high voltage is converted into direct current by the rectifier circuit and supplied to the load (corona discharger). The voltage Es corresponding to the load current (discharge current) is detected by the output detection circuit 63, and this is fed back to the input terminal of the comparator 62. Therefore, if the duty of the PWM signal input from the timer 31 to this power supply is constant, the load current flowing through the corona discharger is controlled to a constant value. Further, by adjusting the duty of the signal output from the timer 31, the load current flowing in the corona discharger can be changed according to the adjustment.

The B power source 5 and the BR power source 15 are constant voltage power sources which output a DC voltage (about 600 V), and control for stabilizing the output voltage. The circuit configuration and operation are the same as those of the C power supply 3, except that the circuit for detecting the output current is changed to the circuit for detecting the voltage.

PT transformer 7, D transformer 11, and P
Each of the C transformers 13 outputs AC biased AC power (AC500 Hz, 5500 Vrms) for corona discharge, and has a circuit for stabilizing the output current. These transformers 7, 11 and 13 have the same configuration. The structure of one circuit is shown in FIG. In this circuit, the output stabilization control is performed by the control circuit 30, which will be specifically described with reference to FIG.

The transistors Q2 and Q3 are alternately turned on / off as shown in FIG. 16 by the pulse signal supplied from the 500 Hz common oscillating circuit 36 which is common to the other transformers (VQ2, VQ3). Therefore, on the secondary side of the high voltage transformer HVT2, positive and negative times (T4, T5)
And an AC high voltage of a rectangular wave having the same peak value (V +, V-) is induced.

Each transformer has a 500 Hz common oscillation circuit 36.
The pulse signal from is shared. Therefore, the waveform of the AC voltage induced on the secondary side of each transformer is synchronized. The voltage value of this AC high voltage becomes a value proportional to the DC voltage supplied from the AC drive circuit 33 to the high voltage transformer HVT2.

The AC component driving circuit 33 constitutes a chopper type DC / DC converter as shown in FIG. 17, and the output voltage corresponds to the duty of the PWM signal supplied from the AC component timer 32 to the base of the transistor Q6. It becomes the value. The cycle of this PWM signal is about 20 KHz. Therefore, the AC component of the high voltage output can be adjusted to an arbitrary value by the duty of the PWM signal output from the AC component timer 32.

For the DC component, the high voltage transformer HVT3
The output voltage is output between the high voltage transformer HVT2 for AC and ground. Therefore, the load (between HV and ground) is supplied with a voltage obtained by DC-biasing the AC component by VDC (V) as shown by the broken line in FIG.

The DC component voltage is amplified by the DC component driving circuit 35 for the PWM signal (0.05 msec) output from the DC component timer 34 and supplied to the base of the transistor Q4 to switch the transistor Q4. Let
It is made by rectifying the high voltage induced on the secondary side of the high voltage transformer HVT3. Therefore, like the AC component, the DC component of the high voltage output can be set to an arbitrary value by the duty of the PWM signal output from the DC component timer 34.

Next, the output control of the transformers 7, 11, 13 will be described. The overall output control is executed according to the “output detection scan” process shown in FIG. 18, but the details of the individual output control will be described here.

The output voltage and current are detected as low voltage by the output detection circuit 65, and the voltage detected by the transformer output detection circuit 37 is applied to the input terminal for A / D conversion of the control circuit 30. The processing of the detected voltage is executed according to the flowchart shown in FIG. 19 at a predetermined cycle (for example, 14 msec).

That is, first, the detection voltage fetched by the control circuit 30 is converted into digital data, and a proportional constant (fixed value) is set to a difference between the digital data and a preset target value (hereinafter referred to as "error data"). ) Multiplied by the change,
In addition to the current setting value (manipulation amount) of the PWM timer, the result is written in the PWM timer as a new setting value.

Further, the output voltage is detected at a cycle longer than the detection of the output current (for example, 100 msec) and processed according to the flowchart shown in FIG. In this process, the load state is detected by determining whether the output voltage is within the reference range, and the process corresponding to each state is performed.

Referring to FIG. 20, first, the detected output voltage is converted into digital data, and it is determined whether or not the conversion result is within the range of a predetermined reference value. When the detection data is HLMT or more or LLMT or less,
Since a serious abnormality is expected to occur in the load, the output abnormality flag FHLMT or FLLMT is set, the current processing is interrupted, and the interrupt processing of "output abnormality: 1" is executed.

Next, the output detection procedure of the transformer will be described. Since the output control of each transformer is collectively performed by the control circuit 30, the detection signal is fetched and processed in a predetermined procedure. Of the output detection signals shown in FIGS. 21 and 22, the former No. 1 to No. No. 6 of the latter with a period of 14 msec. 1 to No. Up to 6 are detected and processed in a cycle of 84 msec. A flowchart of this process is shown in FIG.

This processing is executed in the control circuit 30 by an FB interrupt which arrives every 2 ms. In this processing, a counter based on two programs is provided. One I-scan counter counts each time this subroutine is executed (2 msec cycle), and the other V-scan counter counts each I-scan counter count-up (14 msec cycle). The count value of each scan counter is associated with the detection signal shown in FIGS.

The details will be described below with reference to the flowchart of FIG. When the FB interrupt occurs, the I-scan counter is decremented and the corresponding detection value is selected.
And first, the alternating current output current PTIAC of the PT transformer 7
When it is detected, it is determined whether or not the output of the PT transformer 7 is in the on (trigger on) state. If it is off, this processing is ended. If it is on, the output detection signal PTIAC is sent to the control circuit 30.
Take in the A / D converter of.

Next, the "constant current control" subroutine shown in FIG. 19 is executed, and this processing ends. When the next FB interrupt occurs, PTIDC is detected. After that,
DIAC, DIDC, PCIAC, PCI for each FB interrupt
Output detection is performed in DC order. After that, FB
When an interrupt occurs, the V-scan counter is decremented and the subroutine shown in FIG. 23 is processed.
Here, the AC voltage VAC of the PT transformer 7 is detected,
The "output voltage detection" subroutine of FIG. 20 is executed.

Next, when the I-scan counter is reset and an FB interrupt occurs, detection is performed from the first PTIAC. Therefore, every time the detection of the signal shown in FIG. 21 is completed, the signals shown in FIG. 22 are detected one by one. Next, detection of the photoconductor charging current Id flowing by corona discharge in each corona discharger will be described. Figure 24
2 shows a specific configuration of the Id detection circuit 2.

The conductive substrate of the photoconductor 1 is the Id detection circuit 2
It is grounded via a detection resistor Rs (for example, 10 KΩ) provided inside. Therefore, when a current flows through the photoconductor 1 due to corona discharge, the current passes through the resistor Rs, so that a voltage corresponding to the current Id flowing through the photoconductor 1 is generated between both terminals of the resistor Rs.

In this Id detection circuit, the voltage generated in the resistor Rs is separated into three types of components, each of which is A / D converted by the control circuit 30. That is, the positive polarity component of the voltage is applied to the terminal A / D1 via the + minute rectification circuit composed of the diode D1, the capacitor C1 and the resistor R1, and the negative polarity component of the voltage is the diode D2, the capacitor C2, the resistor R2 and The AC component of the voltage, which is applied to the terminal A / D2 via the minus rectification circuit constituted by the polarity reversing circuit, is the capacitors C3, C4, the diode D3.
It is applied to the terminal A / D3 via an AC rectifying circuit composed of D4 and a resistor R3.

Therefore, the control circuit 30 can simultaneously measure the positive polarity component, the negative polarity component, and the alternating current component of the voltage generated across the resistor Rs, and detect the sum of the positive polarity component and the negative polarity component. By doing so, the magnitude of the DC component included in the AC signal can be detected. In the photoconductor charging current setting mode, these three types of signals applied to the A / D converter of the control circuit 30 are selected according to the corona discharger to be detected and the measurement is performed.

Next, the photoconductor charging current setting mode will be described. Roughly speaking, the high-voltage output value when the photoconductor charging current Id is set to a predetermined value is made constant, so that the photoconductor charging current Id is substantially made constant.
The specific contents are as follows.

In the photoconductor charging current setting mode, corona discharge is individually performed for each corona discharger, the value of the PWM timer or the target value of proportional control is varied, and the detected value by the Id detection circuit 2 is a predetermined value. The output current value when the (predetermined photoconductor charging current) is reached is stored, and constant current control is performed with this current value as the target value.

The output current Io of the corona discharger is divided into the photoconductor charging current Id and the casing current Ic as shown in FIG. 12, but the ratio of Io to Id is usually the toner or paper powder in the corona discharger. It changes only due to dirt caused by. Therefore, if the target value of the output current Io is corrected in a predetermined cycle in which a change due to dirt can be allowed, the value of Id can be controlled by the output current Io without measuring the actual photoconductor charging current Id. Therefore, as described above, this setting is performed when the power is turned on and each time the image forming process for copying is completed.

In this photoconductor charging current setting mode, the setting method is different between the power sources 3, 9, 17 and the transformers 7, 11, 13. In the former case, the set value of the DC high voltage timer 31 is directly operated to set the photoconductor charging current Id, whereas in the latter case, the target value of the proportional control is operated.

FIG. 25 shows the contents of the actual processing relating to the former. In this process, first, the output of the power supply is turned on (trigger on). The output current at this time changes according to the duty of the PWM signal determined by the value currently set in the PWM timer. At the initial stage, a standard set value determined in advance is set in the PWM timer.

Next, after waiting for 100 msec, the detection signal of the photoconductor charging current Id detected by the Id detection circuit 2 is set to A /
D conversion is performed, and it is determined whether or not the detected data is within a predetermined target value range. Then, when it is within the target value, the process ends as it is, and when it is outside the target value, a new set value obtained by increasing or decreasing the current set value of the DC high-voltage timer 31 which is the PWM timer is set in the AC minute timer 32, The above process is repeated until the detection data falls within the target value.

FIG. 26 shows the contents of actual processing relating to the latter. In this process, first, the constant current control subroutine shown in FIG. 19 is executed several times (for example, five times) to sufficiently raise the high voltage output, then the Id detection process and the A / D conversion, and the detection data determination. Do. As a result of the judgment, when the detected data is out of the target value, the target value of the proportional control of the "constant current control" subroutine is increased or decreased with respect to the current value, and the detected data is the target of the photoconductor charging current Id. The above process is repeated until the value falls within the range.

Next, the process of the photoconductor charging current setting mode will be described with reference to FIG. First, after rotating the photoconductor 1, the static elimination corona discharger 18 is discharged with an output current corresponding to the count value preset in the DC timer 31 to uniformly charge the entire circumference of the photoconductor 1. After-discharge is stopped. Simultaneously with this charging, the static elimination lamp 22 is turned on to perform photo static elimination. The static elimination lamp 22 is lit until this mode ends.

Next, the positive charging current Id of the photoconductor by the discharging corona discharger 18 is shown in FIG.
Set according to the "1" subroutine. Then, similarly, the transfer corona discharger 10 and the charging corona discharger 4 are set according to "Id setting: 1". When the charging corona discharger 4 is set, the eraser 23 is turned on to perform optical static elimination.

Next, the setting is made for each corona discharger which carries out a DC biased AC corona discharge. In this case, the AC component is set first and then the DC component is set. First, the AC component of the PT corona discharger 8 is shown in FIG.
After setting according to the subroutine of "d setting: 2", the setting of the direct current component is also performed using "Id setting: 2".
This DC component is detected as a difference between positive and negative polarities as described above, and is compared with the target value.

Next, after the entire periphery of the photoconductor 1 is uniformly charged by the static elimination corona discharger 18, the setting is made by the separation corona discharger 12 and the PC corona discharger 14 like the PT corona discharger 8. .. After setting the PC corona discharger, stop the photoconductor and turn off the static elimination lamp.

Although the embodiment in which the present invention is applied to the corona discharge device in the copying machine has been described above, the present invention is not limited to this, and an optical printer such as a laser printer, an LED printer, a liquid crystal shutter printer, a facsimile machine, or the like. It can also be applied to a corona discharge device in another electrophotographic image forming apparatus.

[0089]

As described above, according to the present invention, by detecting the current flowing through the photoconductor that is normally used, the corona discharge current can be measured without replacing the photoconductor with a special jig. Adjustments can be made. Moreover, since the information on the inclination of the corona discharger with respect to the photoconductor is output based on the detected current, the inclination of the corona discharger can be easily adjusted without specially preparing an ammeter or the like. Therefore, the maintenance is simplified, the required time is significantly shortened, and the downtime of the apparatus is significantly reduced.

Further, when detecting the inclination of the corona discharge electrode, when a part of the current flowing to the photosensitive member is interrupted by the mask of the shunting means, the interrupted current is diverted to the current detecting means. The discharge current and current can be accurately detected under the conditions. Furthermore, if the shunting means is detachably attached to the corona discharger and the shunting means is automatically electrically connected to the ground when mounted,
The tilt can be detected safely and easily.

[Brief description of drawings]

FIG. 1 is an explanatory diagram relating to inclination adjustment of a corona discharge electrode in each corona discharger of FIG.

FIG. 2 is a main part configuration diagram showing an image forming unit of a copying machine embodying the present invention and a high voltage power source device for corona discharge or the like connected thereto.

3 is a flowchart showing a copying process by a main controller of the copying machine shown in FIG.

FIG. 4 is a flowchart showing a process related to a high voltage generator by the control circuit 30 of FIG.

5 is an exploded perspective view showing a main part of each corona discharger of FIG. 2. FIG.

FIG. 6 is an S diagram according to the present invention by the control circuit 30 of FIG.
It is a flowchart which shows the process of P mode.

FIG. 7 is a perspective view showing an example of the mask 50 of FIG.

FIG. 8 is a circuit diagram of the control circuit 30 of FIG.
It is a flowchart which shows the process of R adjustment mode.

9 is a perspective view showing a mask different from the mask 50 of FIG. 7. FIG.

FIG. 10 is a perspective view showing a mask different from the masks of FIGS. 7 and 9;

11 is a perspective view showing a mask different from the masks of FIGS. 7, 9 and 10. FIG.

12 is a circuit diagram showing a configuration of a charging high-voltage power supply 3, a transfer high-voltage power supply 9, and a charge removal high-voltage power supply 17 of FIG.

13 is a PW output by the DC high voltage timer 31 of FIG.
It is explanatory drawing for demonstrating M signal.

14 is a diagram showing the relationship between the duty of the pulse signal output from the pulse width modulation circuit 64 and the high voltage generated in the secondary winding of the high voltage transformer HVT1. FIG.

15 is a circuit diagram showing a configuration of a pre-transfer static elimination high-voltage power supply 7, a separation high-voltage power source 11, and a pre-cleaning static elimination high-voltage power source 13. FIG.

16 is a timing chart for explaining the operation of transistors Q2 and Q3 in FIG.

17 is a circuit diagram showing a configuration of an AC drive circuit 33 of FIG.

18 is a flowchart showing an output detection scan process by the control circuit 30 of FIG.

FIG. 19 is a flowchart showing a constant current control subroutine of FIG. 18.

20 is a flowchart showing a subroutine of the output voltage detection processing of FIG. 23.

21 is an explanatory diagram for explaining the output detection scan processing of FIG. 20. FIG.

FIG. 22 is an explanatory diagram for explaining the V-scan processing of FIG. 23.

23 is a flowchart showing a subroutine of V-scan processing in FIG.

FIG. 24 is a circuit diagram showing a configuration of a photoconductor current detection circuit.

FIG. 25 is a flowchart showing a process of photosensitive member charging current setting 1 by the control circuit 30 of FIG.

FIG. 26 is a flow chart showing a process of similarly setting the charging current of the photoconductor.

FIG. 27 is a flowchart showing the processing of the photosensitive member charging current setting mode in the same manner.

[Explanation of symbols]

1 Photoconductor 2 Photoconductor current detection circuit (Id detection circuit) 3 Charging high voltage power supply (C power supply) 4 Charging corona discharger 7 Pre-transfer static elimination high voltage power supply (PT transformer) 8 PT corona discharger 9 Transfer high voltage power supply (T power supply) 10 Transfer Corona Discharger 11 Separation High Voltage Power Supply (D Transformer) 12 Separation Corona Discharger 13 Eliminating High Voltage Power Supply (PC Transformer) Before Cleaning 14 PC Corona Discharger 17 Electrification High Voltage Power Supply (PQ Power Supply) 18 Electrification Corona Discharger 30 Control Circuit ( C
PU) 41 Corona discharge electrode 42 Adjustment screw 43 Shield electrode 43a Sliding part 50, 52, 53, 56 Mask 50a Notched hole 51, 52a, 54a, 54b, 54c, 54d, 57
Conductive electrodes (pattern) 55a, 55b, 55c Printing resistor 58 Shunt terminal

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] June 6, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0002

[Correction method] Change

[Correction content]

[0002]

In general, in an image forming apparatus such as a copying machine, a drum-shaped or belt-shaped photosensitive member and several corona discharger its periphery in the image forming unit is disposed, with its corona discharger Corona discharge is generated between the photoconductor and the discharge current, and the photoconductor is charged and discharged. Since the amount of charge on the photoconductor has a great influence on the image formed, in order to achieve good image formation,
It is necessary to accurately control the corona discharger to by that the discharge amount and the like.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

By the way, this type of corona discharger is contaminated by adsorbing toner, paper powder and dust in the air after long-term use. Since this kind of dirt has an adverse effect on the discharge state, periodical cleaning and maintenance work such as replacement of the corona discharger are required. When the corona discharger is replaced, the electrodes of the corona discharger ( for example, the diameter is about 80μ
Since the distance between the wire of m) and the photoconductor changes, the distance between the wire of the corona discharger and the photoconductor ( L1, L2 in FIG. 1B) should be set to obtain an image of uniform density . I have to adjust.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

In this type of adjustment work, conventionally, the photoconductor is first removed from the image forming apparatus, a pseudo photoconductor (jig drum) is incorporated in place of the photoconductor, and a discharge current is applied at both ends in the axial direction of the photoconductor. While measuring alternately, turn the adjusting screw provided on the front side of the corona discharger to make adjustment so that the discharge currents at both ends of the corona discharger become equal, and then remove the pseudo photoconductor and replace the photoconductor instead. I was wearing it.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

[0010]

[Action] In the corona discharge apparatus according to the present invention, to cut off the part of the discharge current flowing to the photoreceptor side by diversion means to flow by bypassing the current detector discharge current in the blocked
I can . Therefore, without using a pseudo-photoreceptor , the discharge from the corona discharger to the photoconductor is interrupted except for one end in the longitudinal direction of the corona discharger, and the discharge current (the magnitude is (Proportional to the distance between the one end and the photoconductor).

[Procedure Amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

Further, by using a corona discharge apparatus according to the invention of claim 2 to 6, more inclination adjustment of the corona discharger
It will be easier .

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0013

[Correction method] Change

[Correction content]

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 2 shows the structure of an image forming unit for a copying machine embodying the present invention and a high-voltage power supply device for corona discharge or the like connected thereto. To explain this, the drum-shaped photosensitive member 1 provided in the image forming unit is indicated by an arrow O in the figure.
Rotate in the direction indicated by. The photoconductor 1 is grounded via a photoconductor current detection circuit (hereinafter referred to as “Id detection circuit”) 2.

[Procedure Amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0014

[Correction method] Change

[Correction content]

Around the photosensitive member 1, a developing corona discharger 4 connected to a charging high voltage power source (hereinafter referred to as C power source) 3, a developing bias power source (hereinafter referred to as B power source) 5 and a developing sleeve 6a. Including a developing device 6, pre-transfer static elimination high-voltage power supply (hereinafter referred to as PT transformer) 7, PT corona discharger 8, transfer high-voltage power supply (hereinafter referred to as T power supply) 9, transfer corona discharger 10, Separated corona discharger 1 connected to separated high-voltage power supply (hereinafter referred to as D transformer) 11.
2, a cleaning device 1 including a PC corona discharger 14 connected to a high voltage power supply (hereinafter referred to as a PC transformer) 13 for pre-cleaning charge removal, and a bias roller 16a connected to a cleaning bias power supply (hereinafter referred to as a BR power supply) 15
6, and a static elimination corona discharger 18 connected to a static elimination high voltage power source (hereinafter referred to as PQ power source ) 17.

[Procedure Amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0016

[Correction method] Change

[Correction content]

The control circuit provided in the high-voltage power supply apparatus (CP
The U) 30, via the bus line 21, both PW
DC high-voltage timer 31, which is an M (pulse width modulation) timer,
An AC minute timer 32 and a DC minute timer 34 are connected. The DC high voltage timer 31 outputs a high DC voltage 5
It is connected to three power sources 3, 5, 9, 15, and 17. The AC minute timer 32 is connected to the AC minute drive circuit 33, and the DC minute timer 34 is connected to the DC minute drive circuit 35.

[Procedure Amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

Each transformer 7, 11, 13 has an AC
Voltage DC and are superimposed AC and DC component driving circuit 35 min drive circuit 33 outputs to the output is applied. Also ,
Each 500Hz common oscillation circuit 36 and the transformer output detection circuit 37 is connected. The control circuit (CPU) 30 is
It is connected via a serial data communication circuit to a main controller (not shown) that controls the operation of the entire copying machine.

[Procedure Amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction content]

Next, the image forming process by the copying machine of FIG. 2 will be briefly described. Photosensitive layer mainly composed of selenium
The drum-shaped photoconductor 1 having the outer peripheral surface is formed by a corona discharge by the charging corona discharger 4 and has a positive high potential (about 8
00V). The reflected light obtained by exposing the original image is formed on the charged surface, and thereby a potential distribution corresponding to the intensity distribution of the reflected light, that is, an electrostatic latent image is formed.

[Procedure Amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

[0035] In this adjustment, as shown in the (b) Figure 1, the slope is corrected by adjustment of the front of the distance L1 and the distance of the rear side L2 of the corona discharge electrode 41 with respect to the photosensitive member 1. Regarding the corona discharge electrode 41, the height can be adjusted only on the front side F by rotating the adjusting screw 42 as shown in FIG . Therefore, the adjustment screw 4
The inclination can be corrected by rotating 2.

[Procedure Amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0036

[Correction method] Change

[Correction content]

Now, the processing of the SP mode by the control circuit 30 of FIG. 2 will be described with reference to FIG . This SP
The mode is designated by switching a dip switch (not shown) mounted on the apparatus body. After entering the SP mode, a mode for maintenance is selected by a key operation on the operation panel (not shown). If an instruction to select the FR adjustment mode is given here, first, on the operation panel. "Instruction to attach the front side of the mask (flow dividing means)" is displayed.

[Procedure Amendment 13]

[Document name to be amended] Statement

[Name of item to be corrected] 0037

[Correction method] Change

[Correction content]

[0037] Therefore, the operator in accordance with the display, as shown in FIG. 7
The mask 50 as shown in FIG. 3 is attached to the shield electrode (case) 43 of the corona discharger so that the cutout hole 50a is on the front side (F side). The shield electrode is
A slide portion 43a (holding means) for holding the mask 50 is formed, and the mask 50 is fitted and attached to this portion.

[Procedure Amendment 14]

[Document name to be amended] Statement

[Correction target item name] 0041

[Correction method] Change

[Correction content]

When the print key on the operation panel is pressed, the FR adjustment mode start flag is transmitted as an interrupt to the control circuit 30 of the high voltage power supply device. As a result , the control circuit 30 executes the processing of the FR adjustment mode as shown in FIG. 8 , so that a predetermined high voltage is applied to the electrode 41 of the corona discharger, and the photoreceptor 1 is subjected to the corona discharge. Corona discharge current flows.

[Procedure Amendment 15]

[Document name to be amended] Statement

[Correction target item name] 0042

[Correction method] Change

[Correction content]

However, since the mask 50 is attached to the corona discharger and the cutout hole 50a is located on the front side (F side) at this time, only the position of the cutout hole 50a is as shown in FIG. Then, a corona discharge current (FId) flows through the photoconductor 1. Further, the corona discharge current (Id-FId) of the portion blocked by the mask 50 is shunted by the conductive pattern 51 on the mask 50 and is grounded (case ) through the shield electrode 43 of the corona discharger. It flows to.

Claims (6)

[Claims] 1. A corona discharger arranged to face a photoreceptor of an image forming apparatus, a power supply for supplying a high voltage to the corona discharger, and a control means for controlling the power supply to adjust a discharge current. In a corona discharge device including: a current detecting unit that detects a current flowing through the photoconductor, and a shunt unit that cuts off a part of the discharge current flowing toward the photoconductor side and bypasses the current detecting unit. A corona discharge device characterized in that 2. The corona discharge device according to claim 1, further comprising: information output means for outputting information corresponding to the inclination of the corona discharger with respect to the photoconductor, based on the current detected by the current detection means. Corona discharge device characterized by. 3. The corona discharge device according to claim 1, wherein the corona discharger is provided with a holding unit to which the flow dividing unit can be attached and detached. 4. The corona discharge device according to claim 3, wherein the flow shunting means is constituted by a mask which blocks discharge from the corona discharger to the photoconductor except for one end portion in the longitudinal direction of the corona discharger. Characteristic corona discharge device. 5. The corona discharge device according to any one of claims 1 to 4, wherein a part of a bypass path formed by the flow dividing means is formed by a shield electrode of the corona discharger. apparatus. 6. The corona discharge device according to claim 2, further comprising rotation adjusting means for adjusting the inclination of the corona discharge electrode of the corona discharger, wherein the diversion means is detachable from the corona discharger. A part of the opening of the corona discharger that faces the photoconductor is closed, and the information output means is calculated based on the difference between the currents detected at both ends of the photoconductor in the axial direction. The corona discharge device is configured to output the numerical value in association with the rotation amount of the rotation adjusting means.