JP2898806B2 - Image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus in which a toner image can be directly adhered to plain paper or other recording material without passing through a photosensitive drum or other latent image carrier, and more particularly, to an electromagnetism apparatus. The present invention relates to an image forming apparatus in which a toner carrier that carries toner and a back electrode are arranged to face each other via a control grid in which openable and closable toner passage holes are arranged in a matrix.

[0002]

2. Description of the Related Art Conventionally, image formation in which toner carried on a developing roller is directly transferred onto a recording material in a dot pattern corresponding to image information without using a photosensitive drum functioning as a latent image carrier. The device is disclosed in JP-A-3-168766.
To 70, etc., and such a device configuration will be briefly described based on the schematic diagram shown in FIG.
51 rotatably supports the developing roller 50,
A toner container 53 having a band-shaped opening 51a formed on the lower surface side; 53, a control grid in the form of a matrix stretched over the band-shaped opening 51a; 52, a back electrode disposed to face the control grid 53 via a predetermined gap; A power supply circuit for applying a developing bias to the electrodes; 55, a control circuit for generating a signal corresponding to image information; 56, a drive circuit for switching the control grid 53 based on the signal; 57, a spring biased from the bottom surface 57a through the back electrode 52
Is a support plate for positioning and fixing the position at a predetermined position.

[0003] The operation of such an apparatus will be briefly described below. The magnetic toner contained in the toner container 52 is regulated in layer thickness by a doctor blade 51b and then controlled by a control grid 5a.
The developing roller 5 is guided by a power supply circuit 54 provided on the back electrode side in the developing position.
0 and a back surface electrode 52 are applied with a developing electric field. In this state, by energizing the control grid 53 in the X-Y axis directions based on signals from the control circuit 55 and the drive circuit 56, the matrix-shaped toner passage holes 53a are formed.
The recording material 58 is inserted into the surface of the back electrode 52 in synchronization with the image information by selectively blocking or conducting the development electric field acting on the toner according to the image information. A predetermined image can be formed while the toner corresponding to the image information is transferred from the developing roller 50 to the recording material 58 side.

[0004] Accordingly, such a technique is based on the control grid 53.
In order to adopt a configuration in which a dot pattern corresponding to the image information is formed on the recording paper while allowing the toner to pass through the toner passage hole 53a, an insulating layer is formed around the control grid 53 and the toner passage hole 53a. Because the toner is covered, the toner is electrostatically attracted by the rubbing that occurs between these portions and the toner, and the smooth passage of the toner is prevented, and the image pattern formed on the recording paper is disturbed. .

In order to eliminate such a drawback, the present applicant first applies an electric vibration to the toner by applying a fluctuating voltage to the control grid 53 during non-image formation, so that the toner is applied to the recording paper passing through the back electrode 52. The technique of dropping the toner is applied, and a voltage having the same polarity as the charged potential of the toner is applied to the control grid 53, and a reverse bias developing electric field is applied to pull the toner back to the developing roller 50 side. Propose technology. (JP-A-3-168767)
issue)

[0006]

In any of the above-mentioned techniques, even if electric vibration is applied to the control grid, the amount of the vibration is limited. The transferred toner is generally on the downstream side in the transfer direction. Since it is adsorbed on the back electrode side, it is not easy to pull it back in the opposite direction. For this reason, at the time of non-image formation, for example, a state where application of the control voltage to the control grid is stopped,
In other words, by applying a developing bias to the back electrode side while the electromagnetic toner passage hole is open, the toner adhering around the toner passage hole is collected on the recording paper inserted through the back electrode side. Although it is conceivable to use a means for causing the recording paper to wastefully be used for each cleaning operation in the above-described configuration, and when an image is fixed to a recording paper having toner adhered to solid black each time, the above-described configuration is required. Because the solid black toner is thicker compared to normal image formation,
The toner easily adheres to the fixing device side, and there is a problem in maintenance.

However, it is very difficult to separate the toner adsorbed by the frictional charging by the force of only the electric field of the developing bias. Therefore, a cleaning method or a mechanical sliding method in which the control grid is blown off by air or the like is used. Although cleaning methods by rubbing are also being studied, all of them are performed with extremely narrow slit gaps between the back electrode and the control grid, which makes it difficult to arrange the cleaning means. It is difficult to uniformly and reliably remove the entire area of the control grid having the area at the image forming position of the narrow slit gap.

In view of the drawbacks of the prior art, the present invention makes it possible to remove the toner adherence to the control grid uniformly and reliably by a simple cleaning means, and to remove the toner without complicating the maintenance work. Accordingly, an object of the present invention is to provide an image forming apparatus capable of forming a precise and clear image without causing image disorder. Another object of the present invention is to provide a so-called earth-friendly image forming apparatus in which the toner collected from the control grid can be reused without being discarded.

[0009]

According to the present invention, basically, cleaning is not performed with a very narrow slit gap between the back electrode and the control grid, but the control grid surface is moved and retracted from the image forming position. The toner adhering to the control grid surface is collected by using the cleaning means disposed at the retracted position. That is, the present invention is configured such that the control grid is configured to be movable independently or integrally with the toner carrier in a direction to withdraw from the image forming area, and a grid cleaning unit is provided facing the grid surface , The cleaning means is
A first roller for cleaning residual toner on the control grid surface;
Separating means for separating the residual toner from the first roller
And a magnetic attraction arranged downstream of the separation means.
And a second roller that is sucked and fed by the second roller
And a conveying means for conveying the collected toner to the return passage.
It is characterized by having been done. The movement of the control grid is not particularly limited. However, it is preferable that the control grid be rotated around the fulcrum, because it is easy to return to the original position.

[0010]

According to this technical means, since the cleaning is performed at the position where the control grid is retracted from the image forming position, an extra space necessary for disposing the cleaning means can be easily taken, and the position where the control grid faces the control grid. Since there is no member that obstructs cleaning such as the back electrode, the cleaning means can be disposed directly facing the control grid, so that even when the image forming area of the control grid is widened. Thus, the grid-adsorbed toner can be collected easily and reliably.

Further, the arrangement of the cleaning means in the extra space, ie, the retreat position, allows the cleaning means to be constructed with a free idea without much restriction of the space. For example, a return passage communicating the cleaning means with the toner carrier side. Is provided, and the grid-adsorbed toner caught by the cleaning means can be returned to the toner carrier. And the cleaning means is provided with
A first roller (2) for cleaning residual toner on the grid surface
2,221,222,223, etc.)
Collect the remaining toner and remove the residual toner from the first roller.
By the separation means (scraper 23) for separating the toner
As the toner is loosened, paper dust and toner particles
Separation is performed to some extent, and it is located downstream of the separation means.
A second roller (24) having a magnetic attraction force.
Magnetically attract the toner particles, and further remove the paper dust and toner.
Can be separated. This makes it possible to collect and recycle the attached toner on the control grid in a closed circuit,
A so-called earth-friendly image forming apparatus can be obtained.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention; However, unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention, but are merely illustrative examples. Not just. FIG.
1 shows a schematic configuration of an image forming apparatus according to an embodiment of the present invention, and the configuration will be briefly described along the flow direction of recording paper. paper feed roller for feeding paper conveying path, and 3 registration rollers, the back electrode formed on the horizontal portion the upper surface of the downstream side of the paper guide plate 5 is 4, 6 fixing roller pair, 7 fixing said back electrode 4 This is a transport plate disposed between the roller pair 6. An image unit 10 in which a control grid 8 and a developing roller 9 are integrated is provided on the upper surface side of the back electrode 4, and a cleaning unit 20 is provided above the registration roller 3 on a side of the image unit 10.

The image unit 10 has an opening at the bottom of the toner container 11, accommodates the developing roller 9 in the container 11 so as to face the opening, and has one bottom wall of the opening end slightly downward. A doctor blade 12 extending toward the developing roller 9 is attached to the inclined wall, and the tip of the blade 12 is brought into contact with the peripheral surface of the roller 9. A holding frame 13 for attaching the control grid 8 is fixed to both bottom walls of the opening end, and is stretched in parallel with a predetermined distance with the back electrode 4 in an opening of the holding frame 13 facing the developing roller 9. Have been. The image unit 10 is configured to be rotatable toward the cleaning unit 20 around a rotation fulcrum 14 provided at an upper position in the container 11.

On the other hand, the guide plate 5 forming the back electrode 4 is
A pressure spring 42 configured to swing up and down about a fulcrum 41 provided on the registration roller 3 side, and to urge the lower surface of the back electrode 4 vertically upward; and a guide plate against the spring 42 A solenoid 43 that pushes 5 downward is attached.

[0015] The cleaning unit 20 is 2 as shown <br/> (A), the frame body 21 to open the position facing the imaging unit 10 to the control grid 8 stretched over the bottom side when the rotated A cleaning roller 22 disposed at the opening position, and a collecting roller which is located on the inner side of the cleaning roller 22 and scrapes off toner adhered to the roller 22 with a scraper 23 and then collects the separated toner. Roller 24
And a screw member 26 for transporting the toner to the return passage 25 side communicating with the toner container 11 while sucking the toner from the collection roller 24, and a second screw member 27 disposed in the passage 25. The detailed configuration of the cleaning unit 20 will be described later.

Next, the operation of the embodiment will be described. First, the recording paper is guided out of the paper supply cassette 1 by the paper supply roller 2 and is made to stand by at the registration roller 3. Then, a pulse-like control voltage is applied to the control grid 8 with the developing bias applied to the back electrode 4. The developing electric field acting on the matrix-like toner passage holes can be selectively cut off or turned on in accordance with the image information, while a recording paper is formed on the surface of the back electrode 4 in synchronization with the image by the registration roller 3. As a result, the toner carried by the developing roller 9 adheres to the recording material side via the toner passage hole, and a predetermined image is formed.

The image unit 10 is moved to the position shown in FIG.
After turning from (A) to the state of FIG. 1 (B), a cleaning operation described later is performed. That is, first, the solenoid 43 is operated to lower the guide plate 5 against the spring 42.
After securing the pivoting space of the image unit 10 is lowered by pressing on, the image unit 10 by using the driving system (not shown)
Is rotated to a position facing the cleaning roller 22.

On the other hand, in the cleaning unit 20, for example, as shown in FIG. 2 (A), the two rollers 24, 22 are divided into two magnetic poles by right and left semicircles, and magnetic poles having opposite polarities are arranged so as to face each other. By rotating the rollers 24 and 22 synchronously in this state, the toner adsorbed on the surface of the control grid 8 is magnetically attracted to the first magnet roller 22 (cleaning roller) side and transferred and collected. After the toner adhered to the surface of the toner is scraped off by the scraper 23 and collected by the second magnet roller 24, the toner is collected by the screw member 26 when the toner is moved to a position facing the first screw member 26. While the toner is being sucked from the roller 24, the toner enters the passage 25 side communicating with the toner container 11, and a second screen disposed in the passage 25. The toner container 11 by-menu member 27
To the side.

Although paper dust and toner are mixed and adsorbed on the surface of the control grid 8, they are rubbed on the surface of the control grid 8 by toner spikes carried on the first magnet roller 22. It is possible to transfer to the magnet roller 22 side while doing so. Further, the toner spikes mixed with the paper powder carried on the first magnet roller 22 are
In 3, while the toner is loosened by scraping, only the toner having a magnetic attraction is collected by the second magnet roller 24, while the paper dust and the like fall into the frame 21 without being collected. Thus, paper dust can be separated.

Incidentally, the cleaning roller 22 is (B)
As shown in FIG. 5, the first magnet roller 22 may be replaced by a sleeve 222 containing a magnet assembly 221 and the magnet assembly 221 or the sleeve 222 may be rotated to collect toner. Further, as shown in (C), a brush roller 223 may be used. The toner collected by the second magnet roller 24 (collection roller) is sequentially deposited, and the deposited portion is separated by the first screw member 2.
The rotation of 6 causes the toner to be conveyed to the side of the passage 25 communicating with the toner container 11, and is returned to the side of the toner container 11 by the second screw member 27 disposed in the passage 25.

At the stage when the cleaning operation is completed, the image unit 10 is rotated to the original position, and then the solenoid 43 is turned off, so that the spring 42 is turned off.
As a result, the guide plate 5 returns upward. In addition, a spacer (not shown) is interposed between the guide plate 5 and the image unit 10 to maintain an accurate interval. After the operation is completed, the printing operation is restarted, and the above operation is repeated.

FIG. 3 shows an image forming apparatus according to another embodiment, which differs from the above embodiment in that the rotation center 14 of the image unit 10 is centered on the developing roller 9. As a result, even if the image unit 10 is rotated, the developing roller 9 does not swing, but can follow the image unit 10 and swing to a position where the control grid 8 faces the cleaning roller 22. According to this embodiment, since only the control grid 8 rotates and the developing roller 9 is fixed in position, it is easy to maintain the accuracy between the roller and the back electrode 4 or the like. In this embodiment, the back electrode 4 is separated from the guide plate 5 in order to further maintain the accuracy, and only the back electrode 4 is configured to be swingable up and down.

[0023]

As described above, according to the present invention, since the cleaning operation is performed at the position retracted from the image forming position, the adhesion of the toner on the control grid can be uniformly and reliably removed by a simple cleaning means. This can be removed without complicating the maintenance work. Further, according to the present invention, it is possible to smoothly perform toner cleaning without contaminating recording paper and the like. Further, according to the present invention, the toner collected from the control grid can be reused without being discarded as it is, thereby providing a so-called earth-friendly image forming apparatus. And so on.

[Brief description of the drawings]

FIG. 1A is an overall configuration diagram of an image forming apparatus according to a first embodiment of the present invention, wherein FIG. 1A shows an image forming state, and FIG. 1B shows a cleaning operation state.

FIG. 2 shows various modifications of the cleaning unit shown in FIG.

FIG. 3 is an overall configuration diagram of an image forming apparatus according to another embodiment of the present invention, wherein (A) shows an image forming state and (B) shows a cleaning operation state.

FIG. 4 is an overall configuration diagram of an image forming apparatus according to the related art.
Is shown.

[Explanation of symbols]

 Reference Signs List 4 back electrode 8 control grid 9 toner carrier 11 toner container 20 cleaning means 25 return passage

Claims (1)

(57) [Claims] (1)In the image forming state,Open and close electromagnetically
Do not arrange the possible toner passage holes in a matrix.
Record the toner carrier and surface via a control grid
With a back electrode that allows the material to moveButFace-to-face arrangementAs well as
The control grid on the back electrode side in an image forming state
The image forming area in the direction where the
Can be moved and evacuatedIn an image forming apparatus comprising:Cleaning means for cleaning the toner;
If a return passage for returning to the toner carrier side is provided,
In the meantime, The cleaning means includes a residual toner on the control grid surface.
A first roller for cleaning the toner, and the remaining roller from the first roller.
Separating means for separating the residual toner;
A second roller having a magnetic attraction disposed therein;
The toner that is sucked and sent by the rollers is returned to the return passage.
And transport means for transporting the The toner captured by the cleaning means is supplied to the return passage.
Can be returned to the toner carrier side through Specially
An image forming apparatus.