JP2002086789A - Imaging apparatus and cleaning method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an imaging apparatus where developer removed by cleaning does not float in the apparatus. SOLUTION: At the time of cleaning operation for removing development adhering to a small hole of an insulating basic material, a vibration generating means 264 is controlled to impart mechanical vibration to the insulating basic material 251. A control electrode 261 is applied with a signal for blocking passage of developer through the small hole and a specified voltage is applied to a back face potential applying means 223 thus forming an electric field for flying developer to the side of an image receiving means 221 between the back face potential applying means 223 and a developer carrying means 214.

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 applied to a copying machine, a facsimile machine, a printer, and the like, and more particularly, to an image forming apparatus for ejecting a developer to a recording member to form an image. .

[0002]

2. Description of the Related Art One of conventional image forming apparatuses employs a direct marking method for forming an image directly on a recording member. For example, an image forming apparatus disclosed in JP-B-44-26333 proposes a developer injection type apparatus which is one of direct marking methods. This is achieved by inputting an image signal to a control electrode provided in the print head to generate an accelerating electric field, passing the charged developer through a small hole near the control electrode, and applying the developer to a voltage applied to a counter electrode. The image is formed by landing on a recording member.

In this image forming apparatus, for example, 100
In order to form a dot of about μm, the small hole of the head must also have a fine dimension of about 100 μm. Therefore, when the image forming operation is repeated, there is a possibility that the small holes are clogged, the dots are thinned, or the dots do not appear.

[0004] This is due to the fact that the developer used for printing adheres to the small holes and the developer is clogged in the small holes, in addition to the dust or dust scattered in the apparatus clogging the small holes. .
Therefore, an appropriate print head cleaning means is required. As this cleaning means, a means has been proposed in which a vibrating body is fixed to an image signal electrode, mechanical vibration is applied to the print head by the vibrating body, and a developer or the like attached to the small holes is removed.

[0005]

However, the conventional image forming apparatus is not provided with a means for attracting the developer removed by cleaning. For this reason, the conventional image forming apparatus has a problem that the developer and the like removed by cleaning from the small holes of the image signal electrodes float in the apparatus and contaminate the inside of the apparatus.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to provide an image forming apparatus in which a developer removed by cleaning does not float in the apparatus.

[0007]

According to the present invention, a vibration generating means is controlled and a mechanical vibration is applied to an insulating substrate during a cleaning operation for removing a developer attached to a small hole of the insulating substrate. A signal is applied to a control electrode for controlling the passage of the developer passing through the small hole so as to prevent the developer from passing through the small hole, and a predetermined voltage is applied to the rear surface potential applying means to carry the developer. An electric field for causing the developer removed by cleaning to fly to the image receiving means side is formed between the developing means and the means.

Thus, the developer removed by the cleaning operation and floating in the apparatus can be fixed on the image receiving means. As a result, the removed developer does not float in the apparatus, and image formation can be performed reliably.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming apparatus according to a first aspect of the present invention comprises a developer carrying means for carrying and transporting a charged developer, and a plurality of small holes through which the developer passes in a plurality of rows. A formed insulating base material, and a control electrode to which a signal for controlling the passage of the developer passing through the small hole, which is disposed around the small hole and opposed to the developer carrying means, is applied. An image receiving unit to which the developer that has passed through the small hole adheres, an image receiving unit to which the developer that has passed through the small hole adheres, and the developer is applied to the image receiving unit side by applying a predetermined voltage. Back potential applying means for forming an electric field to fly, vibration generating means for applying mechanical vibration to the insulating substrate, and vibration generating means for a cleaning operation for removing the developer attached to the small holes Control the mechanical vibration on the insulating substrate Urges employs a configuration provided with the, and control means for applying a predetermined voltage to the back potential applying means applies a signal to block the passage of the developer to the control electrode.

With this configuration, the developer removed by cleaning and floating in the apparatus can be attracted to the back potential applying means and fixed on the image receiving means. As a result, the developer removed by the cleaning does not float in the apparatus. As a result, the image forming operation is continuously and reliably performed. In addition, by using the back potential applying unit normally used for image formation as a unit for attracting the developer floating during cleaning, it is not necessary to add a new configuration.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the control means performs the cleaning operation during a period in which image formation is not performed, and continues from the image forming operation to the cleaning operation. Preferably, the predetermined voltage is applied to the back potential applying means.

With this configuration, it is not necessary to switch the voltage of the back potential applying means in the image forming operation and the cleaning operation. Thus, switching between the image forming operation and the cleaning operation can be performed only by switching the voltage of the control electrode. As a result, switching between the image forming operation and the cleaning operation can be performed smoothly.

A third aspect of the present invention is directed to a cleaning operation for removing the developer adhering to the small holes of the insulating base material in which a plurality of small holes through which the developer passes are formed in a plurality of rows. The developer is applied to a control electrode to which a signal for controlling the passage of the developer passing through the small hole is applied around the small hole by applying a mechanical vibration to the insulating base material. A cleaning method for an image forming apparatus, comprising: applying a signal for preventing passage through a hole; and forming an electric field for causing the developer to fly toward an image receiving unit to which the developer adheres.

Hereinafter, an image forming apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings. FIG.
1 is a cross-sectional view illustrating a schematic configuration of an image forming apparatus 1 according to the embodiment. In FIG. 1, the right side is the front side of the image forming apparatus 1, and the left side is the rear side.

As shown in FIG. 1, the present image forming apparatus 1
The recording paper cassette 10 is arranged near the bottom surface and on the front side. The recording paper cassette 10 has a detachable configuration. Inside the recording paper cassette 10, a recording paper mounting plate 101 is provided. The recording papers 102 are stored in the recording paper cassette 10 in a stacked state such that a part of the recording papers 102 is placed on the recording paper mounting plate 101. A lift unit 103 is provided at an end of the recording paper placing plate 101. The lift unit 103 lifts an end on the rear surface side of the recording paper mounting plate 101 upward by a spring (not shown).

A paper feed roller 105 having a semicircular cross section is provided above the recording paper cassette 10 and on the rear side. The paper feed roller 105 is rotated clockwise by a drive unit (not shown), and feeds the uppermost recording paper 102 into the apparatus.

A recording paper guide 106 is provided slightly behind the paper supply roller 105 in the paper supply direction. A pair of conveying rollers 10 is provided near the front end of the recording paper guide 106.
7 are provided. The transport roller 107 transports the recording paper 102 fed by the feed roller 105 in the same direction. Further, a pair of registration rollers 109 is provided near the rear end of the recording paper guide 106. The registration roller 109 adjusts the conveyance of the recording paper 102 so that the leading end position of the recording paper 102 is aligned with the leading end position of an image formed on a transfer belt described later.

On the other hand, an image forming unit 20 is disposed above these paper feed mechanisms. Image forming unit 20
Is a developing unit 210 for forming a plurality of color images.
And an image receiving unit 220 on which a single-color image formed by the developing unit 210 is superimposed. The developing unit 210 can be moved independently of the image receiving unit 220.
10 can be detached outside the apparatus when maintenance or the like of a constituent member is performed.

The developing unit 210 has flexible printed circuit boards into which developer supply units (hereinafter referred to as developing units) 211a to 211d containing toners as developers of four colors of yellow, magenta, cyan and black are inserted. (Hereinafter, "FPC" (Flexible
Four head units 212a to 212d (referred to as Printed Circuits) are provided above and below.
The FPC head units 212a to 212d are configured to be detachable from an FPC folder unit (not shown) provided in the developing unit 210. The details of the FPC head units 212a to 212d will be described later.

Each of the developing devices 211a to 211d
It is detachable from the PC head units 212a to 212d, and is detached when the toner inside the developing units 211a to 211d is replenished. Further, the developing devices 211a to 211a
On the rear side inside 11d, there are provided developing rollers 214a to 214d as developer carrying means for carrying toner. Such developing devices 211a to 211d are FPC
Pressing portions 215a to 215d formed of springs or the like press from the front side so as to be fixed at predetermined positions when mounted on the head units 212a to 212d.

The image receiving unit 220 includes an endless transfer belt 221 having three belt rollers 222a as image receiving means.
To 222c. The belt roller 222c supports the transfer belt 221, and is connected to a drive motor (not shown), and functions as a drive roller for the transfer belt 221.

At a position inside the transfer belt 221 disposed on the front side and facing each of the developing rollers 214a to 214d, an electric field is applied by applying a predetermined voltage between the developing rollers 214a to 214d. Are provided as back surface electrodes 223a to 223d as potential applying means for forming. In other words, the developing rollers 214a to 214d and the back electrodes 223a to 223 are connected via the transfer belt 221.
d are facing each other.

A box-shaped waste toner unit 230 is provided on the rear side of the belt roller 222a. The waste toner unit 230 is provided in a detachable configuration. Inside the waste toner unit 230, the waste toner unit 23
The shaft 231 is fixedly provided on the housing 0. A blade 232 is attached to the front side of the shaft 231.

The distal end of the blade 232 projects from the housing of the waste toner unit 230. The tip of the blade 232 is just the belt roller 222.
a and comes in contact with the surface of the transfer belt 221 at a position on the rear side. As a result, the toner remaining on the transfer belt 221 such as not being transferred onto the recording paper 102 is scraped off by the blade 232. The scraped toner is stored in the waste toner unit 230.

Here, the developing unit 211 and the FPC head unit 2 which are members constituting the developing unit 210
The configuration around 12 will be described in detail with reference to FIG.
FIG. 2 shows the developing device 211 and the FPC head unit 21.
FIG. 2 is a partially enlarged view showing a configuration around 2; FIG. 2 shows a state in which the developing unit 211 is mounted at a predetermined position with respect to the FPC head unit 212 by the pressing unit 215.

As shown in FIG. 2, on the transfer belt 221 side of the FPC head unit 212, an FPC 251 which is an insulating substrate and is a developer passage control means for controlling the supply of toner from the developing unit 211 is attached. I have. Specifically, one end of the FPC 251 is fixed to the FPC head unit 212 by a fixing screw 252. FPC
The other end of 251 is bent forward by the stay portion 253, and one end of a tension spring 255 is attached to a spring attachment hole 254 formed near the tip of the other end. Further, the other end of the tension spring 255 is connected to the FPC head unit 212.
Is attached to a spring hook 256 provided in the camera. The tension spring 255 pulls the FPC 251 forward. Since the stopper 257 is provided upright at the point where the FPC 251 is pulled, the contact of the FPC 251 with the stopper 257 restricts the FPC 251 from moving further. Thus, the FPC 251 is attached to the FPC head unit 212. The FPC 251 is made of a sheet-like flexible insulating material.

A spacer 258 is fixed to a surface of the FPC 251 on the side of the developing device 211 (hereinafter, referred to as a “back surface of the FPC 251”) slightly above the axis of the developing roller 214. The spacer 258 is in contact with the developing roller 214 to maintain a constant distance between the FPC 251 and the developing roller 214. The transfer belt 221 is located at a position corresponding to the axis of the developing roller 214 of the FPC 251.
A large number of small holes 259 are formed at a fine pitch along the width direction of.

Here, the small hole 2 formed in the FPC 251
The structure around 59 will be described with reference to FIG. FIG.
4 is an enlarged view of the back surface of the FPC 251 and the surface of the FPC 251 on the transfer belt 221 side (hereinafter, referred to as “the front surface of the FPC 251”).

As shown in FIG. 3, the back surface 2 of the FPC 251
A plurality of small hole rows 260 are formed in the small hole 63 by the small holes 259 that are formed. Also, the back surface 2 of the FPC 251
The ring 63 has a ring-shaped image signal electrode (control electrode) 261 formed so as to surround each small hole 259. On the other hand, an aperture electrode 269 is formed on the surface of the FPC 251. In this embodiment, the diameter of the small hole 259 is 145 μm, and the inner diameter of the image signal electrode 261 is 150 μm.
m, a ring shape having an outer diameter of 250 μm, and an aperture electrode 269 having an inner diameter of 250 μm.

Each image signal electrode 261 is also connected to the FPC 2
51 are independently connected to an image signal output unit serving as an image signal voltage switching unit through lead wires wired on the back surface. Normally, a voltage of 400 V or less is applied to the image signal electrode 261. In the present embodiment, a voltage of 300 V is applied for dot formation, and a voltage of -100 V for non-dot formation.

As shown in FIG. 2, the FPC 251 is disposed below the small hole 259 formed in this way and on the back surface of the FPC 251 to remove the toner attached to the inside and around the small hole 259. A vibration mechanism, which is mechanical vibration means for mechanically vibrating, is provided. The vibration mechanism includes a metal vibration plate 264 fixed to the back surface of the FPC 251 along the small hole row 260 and the FPC head unit 2.
And an ultrasonic vibration generator 265 which is fixedly supported on the outer wall of the twelfth and generates ultrasonic vibration.

The diaphragm 264 has a width of, for example, 5 m.
m, a stainless plate having a plate thickness of 0.2 mm can be used. One end of the vibration plate 264 is connected to the ultrasonic vibration generator 26.
5 is screwed and fixed to the output end. The vibration frequency of the ultrasonic vibration generation section 265 may be a sine wave of 1 MHz or less, for example, a frequency of about 20 kHz is suitably used. This is because if the vibration frequency increases, the toner and the FPC 251 vibrate in the same manner, and it becomes impossible to prevent the toner from adhering and accumulating. The vibration plate 264 is configured to transmit ultrasonic vibration while allowing the ultrasonic vibration generation unit 265 and the vibration plate 264 to mutually move relative to each other.

On the other hand, the developing device 211 has a developing roller 21
4, a toner supply roller 266 is provided.
The toner supply roller 266 stirs the toner stored in the developing device 211 to frictionally charge the toner and supplies the toner to the developing roller 214. Further, a toner regulating blade 267 is provided above the developing roller 214. The toner regulating blade 267 regulates the toner layer carried on the developing roller 214.

Further, outside of both ends in the axial direction of the developing roller 214, the developing roller 214 contacts the back electrode 223.
Collar 2 for keeping the distance between the electrode and the back electrode 223 constant
68 are attached. The regulating collar 268 keeps the distance between the back electrode 223 and the developing roller 214 at, for example, 150 to 1000 μm.
It is configured to be set to 0 μm. A drive gear (not shown) for transmitting a rotational driving force to the developing roller 214 is provided to rotate the developing roller 214 in a counterclockwise direction.

The back electrode 223 functions as a counter electrode and forms an electric field with the developing roller 214.
A conductive filler dispersed in a metal plate or resin is used. Although a DC voltage of about 500 to 2000 V is applied to the back electrode 223, a voltage of 1000 V is applied in the present embodiment.

When a voltage of 1000 V is applied to the back electrode 223, the toner carried on the developing roller 214 causes the toner carried on the developing roller 214 side, in other words, the transfer belt 221.
It will be drawn to the side. However, in the present image forming apparatus 1, by adjusting the voltage applied to the image signal electrode 261 provided on the FPC 251,
The toner passing through the small holes 259 is controlled. As a result, a desired recorded image is formed.

FIG. 4 is a schematic diagram showing a configuration around the developing unit and the FPC head unit of the image forming apparatus according to the above embodiment.

As shown in the figure, the potential of the developing roller 214 is set to the ground level. The developer is assumed to be negatively charged.

Returning to FIG. 1, the description of the configuration of the image forming apparatus 1 will be continued. The transfer unit 30 is disposed below the belt roller 222c and on the rear side of the above-described paper feeding mechanism. The transfer unit 30 is provided in a detachable configuration on the rear surface side, and improves the maintainability when a paper jam occurs in the image forming apparatus 1.

A transfer roller 301 is provided above and on the front side of the transfer unit 30 at a position facing the belt roller 222c. It is desirable to use urethane foam as a material of the transfer roller 301. The transfer roller 301 transfers images of a plurality of colors formed on the transfer belt 221 to the recording paper 102. Specifically, the transfer belt 2
The transfer roller 3 electrically transfers the toner constituting the image on the transfer roller 3.
The image is transferred to the recording paper 102 by drawing to the recording paper 102.

On the front side of the transfer roller 301, a recording paper guide 302 formed integrally with the housing of the transfer unit 30 is provided. The recording paper guide 302 transports the recording paper 102 conveyed from the registration roller 109 to the belt roller 2.
It is led to the contact surface between the transfer roller 301 and the transfer roller 301.

A recording paper guide 306 is provided slightly above the transfer roller 301 and on the rear side. The recording paper guide 306 guides the recording paper 102.

As shown in FIG. 1, a fixing unit 40 is disposed in the recording paper guide 306 in the direction in which the recording paper 102 is conveyed. Similarly to the transfer unit 30, the fixing unit 40 is provided in a detachable configuration on the rear surface side, and the maintenance performance when a paper jam occurs in the image forming apparatus 1 is improved.

The fixing unit 40 has a receiving port 401 provided below the housing of the fixing unit 40 for facilitating the reception of the conveyed recording paper 102. Reception 401
The recording paper 102 is provided in a shape that gradually narrows as the recording paper 102 is transported, and also serves as a guide for the recording paper 102. A fixing roller 402 and a heater roller 403 are provided inside the receiving port 401.

Recording paper 1 received from receiving port 401
02 enters the contact surface between the fixing roller 402 and the heater roller 403. The heater roller 403 applies heat to the recording surface of the recording paper 102, and the fixing roller 402 presses the recording paper 102 between the recording paper 102 and the heater roller 403, so that an image is fixed on the recording paper 102.

The oil roller 404 and the cleaning roller 405 are provided so as to contact the peripheral surface of the heater roller 403. The oil roller 404 supplies a predetermined amount of oil to the heater roller 403, thereby enhancing the toner releasability of the heater roller 403.
The cleaning roller 405 is made of, for example, a solid aluminum material. Also, the cleaning roller 405
The temperature of the heater roller 403 is lower than that of the heater roller 403, so that unnecessary toner adhering to the heater roller 403, in other words, toner not fixed on the recording paper 102 is offset toward the cleaning roller 405.
(Fixed).

The recording paper 102 discharged from the contact surface between the heater roller 403 and the fixing roller 402 passes through a transport path 406 formed by the housing of the fixing unit 40. A pair of discharge rollers 407 is provided at the end of the transport path 406. The discharge roller 407 discharges the recording paper 102 transported on the transport path 406 to the outside of the fixing unit 40.

A recording paper guide 408 is provided in the transport direction of the recording paper 102 discharged by the discharge roller 407. The recording paper guide 408 regulates conveyance of the recording paper 102 discharged from the discharge roller 407. This allows
The paper discharge tray 40 arranged below the recording paper guide 408
The recording paper 102 on which an image has been formed is discharged.

Next, a hardware configuration of the image forming apparatus according to the above embodiment will be described with reference to FIG.
FIG. 5 is a block diagram of hardware of the image forming apparatus according to the embodiment.

The main control unit 501 is a CPU or the like, and performs a predetermined process according to a program stored in a storage unit provided in the image forming apparatus 1.

The image forming apparatus 1 is provided with a ROM 502 as a non-volatile memory and a RAM 503 as a volatile memory as storage means. The ROM 502 stores a program that is read and processed by the main control unit 501. The RAM 503 is a work memory, in which image information to be processed is stored, and a program is downloaded.

In the image forming apparatus 1, the recording paper 102 stored in the paper feed cassette 10 is transferred to the image forming unit 20.
A paper feed control unit 504 that controls the lift unit 103, the paper feed roller 105, and the like is provided to send the paper to the printer. The paper feed control unit 504 performs a predetermined process based on a signal from the main control unit 501.

The image forming apparatus 1 has an image signal electrode 261 for forming an image on the fed recording paper.
Is provided with an image signal control unit 505 for controlling the image signal. Specifically, the image signal control unit 505 controls the image signal electrode 26
1. An image signal output unit 50 that outputs an image signal directly to
6 is controlled. The image signal output unit 506 outputs an image signal for controlling an image signal electrode according to a control signal from the image signal control unit 505. A positive voltage of a predetermined value or more is applied to the image signal electrode 261 according to the received image signal. The image signal control unit 505 performs a predetermined operation according to a control signal from the main control unit 501.

The image forming apparatus 1 has a back electrode 22
3 is provided.
The back electrode control unit 507 controls to apply a predetermined voltage to the back electrode 223. The back electrode control unit 507 performs a predetermined operation according to a control signal from the main control unit 501.

The image forming apparatus 1 includes a transfer belt 2
A transfer belt control unit 509 that controls a drive motor 508 that drives the drive 21 is provided. Transfer belt controller 50
9 appropriately controls the transfer belt 221 so that the yellow, magenta, cyan, and black images are sequentially superimposed on the same position on the transfer belt 221. Thus, a color image is formed on the transfer belt 221. The transfer belt control unit 509 appropriately controls the transfer belt 221 according to a control signal from the main control unit 501.

The image forming apparatus 1 has a transfer belt 2
A transfer control unit 510 that controls the transfer roller 301 is provided to transfer the image information formed on the recording paper 21 to the recording paper 102. The transfer control unit 510 performs a predetermined process according to a control signal from the main control unit 501.

Further, the image forming apparatus 1 is provided with a fixing control section 511 for controlling the fixing unit 40 in order to fix the image information on the recording paper 102 on which the image information has been transferred. The fixing control unit 511 performs a predetermined process according to a control signal from the main control unit 501.

Further, the image forming apparatus 1 is provided with a vibration control unit 512 for controlling an ultrasonic vibration generation unit 265 for removing toner adhered inside or around the small hole 259. The vibration control unit 512 controls the ultrasonic vibration generation unit 2 at a predetermined timing according to a control signal from the main control unit 501.
65 is controlled.

The image forming apparatus 1 is provided with an input unit 513 for inputting various information and a display unit 514 for visually displaying various information such as processing status.

Next, an image forming operation of the image forming apparatus 1 according to the above embodiment will be described.

When the image forming apparatus 1 receives a signal indicating that an image is to be formed from the input unit 513, the paper feed control unit 504 controls the paper feed roller 105 and the like to feed the recording paper 102 to the image forming unit 20. When the recording paper 102 is placed at a predetermined position of the image forming unit 20, the small holes 259
The image signal control unit 505 controls the image signal electrodes 2 so as to allow the toner to pass through the transfer belt 221 side.
61 to control the image signal electrode 2 according to an external image signal.
A positive voltage equal to or higher than a predetermined value is applied to 61. At this time, the image forming apparatus 1 controls the back electrode control unit 507 to apply a predetermined voltage to the back electrode 223 in order to attach toner to the transfer belt 221.

When a positive voltage of a predetermined value or more is applied to the image signal electrode 261 in this manner, an acceleration electric field is formed between the developing roller 214 and the image signal electrode 261. Then, the toner of the developing device 211 flies toward the image signal electrode 261. Thus, the flying toner passes through the small hole 259 provided at the center of the image signal electrode 261.
Then, the toner that has passed through the small holes 259 is
3, the toner is pulled in the direction of the back electrode 223, that is, in the direction of the transfer belt 221, and the toner lands on the transfer belt 221. Thus, an image is formed on the transfer belt 221.

The image transferred to the transfer belt 221 moves on the transfer belt 221 and is transferred to the recording paper 102 by the transfer roller 301. Recording paper 102 on which the image has been transferred
, Heat is applied to the recording surface by the heater roller 403. Further, the recording paper 102 on which the image has been transferred is pressed between the fixing roller 402 and the heater roller 403, so that the image is fixed on the recording paper 102.

Incidentally, since the small holes 259 of the image forming apparatus 1 have minute dimensions, there is a possibility that toner or the like may be clogged in the small holes 259 when the image forming operation is repeated. For this reason, in the image forming apparatus 1, the portion where the small holes 259 are formed in the FPC 251 is vibrated by the ultrasonic vibration generation unit 265, and the attached toner is removed from the small holes 259.

However, simply removing the toner or the like from the small holes 259 by vibration causes a problem that the removed toner or the like floats in the image forming apparatus 1 and contaminates the inside of the image forming apparatus 1. Have. In order to solve this, the present invention is intended to suppress the generation of floating toner by attracting toner floating in the apparatus by a cleaning operation by some means.

In view of the above, the present invention focuses on the back electrode 223 which functions to attract toner during an image forming operation, and uses the back electrode 223 to attract toner floating in a cleaning operation. Things.

Hereinafter, the cleaning operation according to the above embodiment will be described in detail with reference to FIG. FIG.
FIG. 4 is a timing chart illustrating vibration control of the image forming apparatus according to the embodiment.

As shown in FIG. 6, the present image forming apparatus 1
When an image is formed, a positive voltage equal to or higher than a predetermined value is applied to the image signal electrode 261 in order to cause toner to fly to a print point on the transfer belt 221. Further, the image forming apparatus 1
Applies a negative voltage of a predetermined value or more to the image signal electrode 261 in order to prevent the toner from flying at the non-printing point of the transfer belt 221.

When printing over a plurality of pages, the image forming apparatus 1 controls the control signal electrodes 26 described above.
The control 1 is repeated for each page.

During the one-page image forming operation, a positive voltage equal to or higher than a predetermined value is continuously applied to the back electrode 223 in order to land toner on a predetermined position of the transfer belt 221.

On the other hand, when performing the cleaning operation, the image forming apparatus 1 controls the vibration control unit 512 between the recording of one page and the recording of the next page, and
56 is driven. Thereby, the small hole 2
The toner adhering to 59 is dropped by vibration.

During the cleaning operation, that is, between pages, a positive voltage of a predetermined value or more is applied to the back electrode 223. As a result, the toner removed from the small holes 259 by the application of the mechanical vibration flies in the direction of the back electrode 223 by the voltage applied to the back electrode 223 and adheres to the transfer belt 221 as in image formation. Can be. Further, since it is not necessary to switch the voltage of the back electrode between pages, it is necessary to increase the voltage of the back electrode 223 from low level to high level.
Time of about 0 ms can be saved, and the image forming operation can be performed at higher speed.

Then, the transfer belt 22 is moved by the ultrasonic vibration.
1 moves on the transfer belt 221,
It is scraped off by the blade 232. The scraped toner is stored in the waste toner unit 230.

This will be described in more detail. As can be seen from FIG. 6, the operation of cleaning the toner adhered to the small holes 259 is performed when the image forming operation is not performed. More specifically, the vibration control unit 51 operates until the image forming operation of a certain page ends and the image forming operation of the next page starts.
2 sends a predetermined signal to the ultrasonic vibration generator 265 to apply vibration to the small hole 259 of the FPC 251. In other words, prior to the cleaning, the image forming apparatus 1 applies a voltage equal to or lower than a predetermined value to the image signal electrode 261, that is, a voltage having a polarity opposite to that during image formation.

As a result, at the time of cleaning, there is no toner that newly flows from the developing roller 214 through the small holes 259 and flies to the transfer belt 221 side. Therefore, at the time of the cleaning operation, it is possible to prevent the toner from flying to the transfer belt 221 side from the developing roller 214 in addition to the toner attached to the small holes 259. Thereby, the transfer belt 221
Pollution can be minimized.

As described above, according to the above embodiment, the toner removed by cleaning is applied to the back electrode 2
Due to the voltage applied to the transfer belt 23, it flies in the direction of the back electrode 223 in the same manner as in image formation, and adheres to the transfer belt 221. As a result, the toner removed by the cleaning does not float in the image forming apparatus 1.

In the above embodiment, the back electrode 223 normally used for the image forming operation is used as a means for attracting the toner removed by the cleaning. For this reason, it is not necessary to add a configuration for attracting the toner newly removed by cleaning.

In the above embodiment, the transfer belt 2
The toner adhering to 21 is stored in waste toner unit 230 without remaining in image forming unit 20. As a result, the image forming apparatus 1 does not contaminate the inside of the apparatus even if the image forming operation is continuously repeated, so that the image forming apparatus 1 can continue to form an image accurately.

Further, in the above embodiment, in the image forming operation and the cleaning operation, since the image forming apparatus 1 applies a positive voltage of a predetermined value or more to the back electrode 223, it is necessary to switch the voltage of the back electrode 223. Absent. Thus, switching between the image forming operation and the cleaning operation can be performed only by switching the voltage of the image signal electrode 261. The switching operation of the image signal electrode 261 is performed by the back electrode 2
It is much faster than the switching of the voltage of 23. For this reason,
Switching between the image forming operation and the cleaning operation can be performed smoothly.

In the above embodiment, the image forming apparatus 1 is described as forming a color image, but may be formed as a monochrome image. In this case, the developing device 21
One may be provided.

Further, the image forming apparatus 1 of the above embodiment can be applied to a facsimile apparatus having an information transmitting / receiving device and an image reading device.

In the above embodiment, the transfer belt 2
Although the description has been made of the form in which the floating toner is attached to 21, the form in which the floating toner is attached to paper or the like may be used.

In the above embodiment, the main control unit 50
1, the paper feed control unit 504, the image signal control unit 505, the back electrode control unit 507, the transfer belt control unit 509, the transfer control unit 510, the fixing control unit 511, and the vibration control unit 512 have been described as separate control units. The functions of these control units are stored in the ROM 502 as programs and stored in the main control unit 50.
1 may be executed.

[0084]

As described above, according to the present invention,
Since the developer removed by the cleaning can be prevented from floating in the apparatus, the inside of the apparatus is not contaminated with the floating developer.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a schematic configuration of an image forming apparatus according to an embodiment of the present invention;

FIG. 2 is a partially enlarged view showing a configuration around a developing unit and an FPC head unit of the image forming apparatus according to the embodiment;

FIG. 3 is an FPC of the image forming apparatus according to the embodiment;
Enlarged view of front and back of

FIG. 4 is a schematic diagram illustrating the periphery of the image forming apparatus according to the embodiment;

FIG. 5 is a block diagram of hardware of the image forming apparatus according to the embodiment;

FIG. 6 is a timing chart illustrating vibration control of the image forming apparatus according to the embodiment;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 20 Image forming unit 210 Developing units 211a to 211d Developing units 212a to 212d FPC head units 214a to 214d Developing rollers 220 Image receiving units 221 Transfer belts 222a to 222c Belt rollers 223a to 223d Back electrodes 251 FPC (Flexible Printed)
Circuit 259 Small hole 260 Small hole row 261 Image signal electrode 264 Vibration plate 265 Ultrasonic vibration generator 501 Main controller 505 Image signal controller 506 Image signal output unit 507 Back electrode controller 512 Vibration controller

Continuing on the front page (72) Inventor Hiroshi Saegusa 2-3-8 Shimomeguro, Meguro-ku, Tokyo Matsushita Electric Transmission System Co., Ltd. (72) Inventor Takahiro Tsujimoto 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture F-term in Matsushita Electric Industrial Co., Ltd.

Claims (3)

[Claims] A developer carrying means for carrying and transporting a charged developer; an insulating base having a plurality of small holes through which the developer passes; and an insulating base material surrounding the small holes. And a control electrode to which a signal for controlling the passage of the developer passing through the small hole, which is disposed to face the developer carrying means, is applied, and an image receiving unit to which the developer passing through the small hole adheres. Back potential applying means for forming an electric field for causing the developer to fly toward the image receiving means by application of a predetermined voltage; vibration generating means for energizing the insulating base material with mechanical vibration; During the cleaning operation for removing the developer adhered to the control member, the vibration generating means is controlled to urge mechanical vibration to the insulating base material, and a signal is transmitted to the control electrode to prevent the developer from passing therethrough. To the back potential applying means. Control means for applying the predetermined voltage,
An image forming apparatus comprising: 2. The method according to claim 1, wherein the control unit performs the cleaning operation during a period in which image formation is not performed, and continuously applies the predetermined voltage to the back surface potential applying unit from the image forming operation to the cleaning operation. The image forming apparatus according to claim 1. 3. A cleaning operation for removing the developer adhering to the small holes of the insulating base material in which a plurality of small holes through which the developer passes is formed in a plurality of rows. For preventing the developer from passing through the small hole to a control electrode to which a signal for controlling the passage of the developer passing through the small hole is applied. A method for cleaning an image forming apparatus, the method comprising: applying a signal that causes the developer to fly, and forming an electric field that causes the developer to fly toward an image receiving unit to which the developer adheres.