JPH05127515A - Image forming device - Google Patents

Abstract

PURPOSE:To provide an image forming device capable of smoothly removing the clogging of a control grid without complexing maintenance work, even if the control grid has the clogging, in an image forming device on which a toner carrier and a rear electrode are oppositely arranged via the control grid. CONSTITUTION:As a characteristic, toner attracted to the control grid 2 by imparting an electric field, or a magnetic field, or a mechanical action, is dropped not on the side of a developing roller 1, but on the side of the rear electrode 3. Especially, the dropped toner is dropped not on a recording form, but on a thin layer body 4 interposed/fitted between the control grid 2 and the rear electrode 3, as a characteristic. Then, the thin layer body 4 is constituted so as to move in a direction where it is retreated from the image forming position of the control grid 2, after the toner is dropped on the thin layer body 4.

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 a plain paper or other recording material without interposing a photosensitive drum or other latent image carrier, and particularly, to an electromagnetic type. The present invention relates to an image forming apparatus in which a toner carrier carrying toner and a back electrode are arranged face-to-face via a control grid in which openable and closable toner passage holes are arranged in a matrix.

[0002]

2. Description of the Related Art 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 has hitherto been performed. The device is Japanese Unexamined Patent Publication No. 3-168766.
To 70 etc., and a brief description of such a device configuration based on the schematic diagram shown in FIG.
51 rotatably supports the developing roller 50,
A toner container having a strip-shaped opening 51a formed on the lower surface side, 53 is a matrix-shaped control grid stretched over the strip-shaped opening 51a, 52 is a back electrode facing the control grid 53 through a predetermined space, and 54 is the back surface. A power supply circuit for applying a developing bias to the electrode 52, a control circuit 55 for generating a signal corresponding to image information, a drive circuit 56 for switching the control grid 53 based on the signal, 57.
Is a support plate for positioning and fixing the back electrode 52 at a predetermined position through a spring 57a biased from the bottom surface.

To briefly explain the operation of the apparatus, the magnetic toner contained in the toner container 52 is regulated by the doctor blade 51b to control the layer thickness, and then the control grid 5 is formed.
3, a power supply circuit 54 provided on the rear electrode 52 side applies a developing electric field between the developing roller 50 and the rear electrode 52 at the developing position. Then, 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 5 are formed.
By selectively blocking or conducting the developing electric field acting on 3a corresponding to the image information and inserting the recording material 58 on the surface of the back electrode 52 in synchronization with the image information, the recording material 58 is passed through the toner passage hole 53a. Thus, 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.

Therefore, such a technique is used in the control grid 53.
In order to form the dot pattern corresponding to the image information 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. Since the toner is covered, the toner is electrostatically adsorbed by the rubbing generated between these portions and the toner, which hinders the smooth passage of the toner and causes disorder in the image pattern formed on the recording paper. ..

In order to solve such a drawback, the present applicant first applied electric fluctuation to the toner by applying a fluctuating voltage to the control grid 53 at the time of non-image formation, and the toner is applied to the recording paper passing through the back electrode 52. The toner is dropped to the developing roller 50 side by applying a voltage having the same polarity as the charging potential of the toner to the control grid 53 and applying a reverse bias developing electric field to the control grid 53. Proposing technology. (JP-A-3-168767
issue)

[0006]

In any of the above techniques, even if an electric vibration is applied to the control grid, the amount of vibration is limited, and even if an attempt is made to pull back by applying a reverse bias, it adheres to the control grid. The formed 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. Therefore, at the time of non-image formation, for example, in a state where the 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 to the periphery of the toner passage hole is collected on the recording paper inserted through the back electrode side. It is conceivable to use the recording paper wastefully each time the cleaning operation is performed in the above-mentioned configuration, and if the recording paper with the toner adhered to the solid black is fixed every time, Since the solid black toner is thicker than that used during normal image formation,
Toner easily sticks to the fixing device side, and there is a problem in terms of maintenance.

Moreover, it is quite difficult to peel off the toner adsorbed by the frictional electrification by the force of only the electric field called the developing bias. Therefore, a cleaning method in which the control grid is blown off with air or the like is also under study. However, the configuration using air requires a blowing pressure equal to or higher than the electrostatic attraction force of the toner, resulting in an increase in the size of the air generator and an increase in cost.

In view of the above-mentioned drawbacks of the prior art, the present invention eliminates the clogging of the control grid and removes it smoothly without complicating maintenance work. An object of the present invention is to provide an image forming apparatus capable of forming a clear image.

[0009]

According to the present invention, the toner attracted to the control grid by applying an electric field, a magnetic field or a mechanical action force is dropped not to the developing roller side but to the back electrode side (the back electrode is not always downward). The term “transfer” is used in the claims because it is not always located.), But the present invention is particularly characterized in that the dropped toner is not on the recording paper but between the control grid and the back electrode. The first feature is that the thin film is transferred to the thin layered body interposed in between.
The second characteristic is that after the toner is transferred onto the thin layer body, the thin layer body can be moved in a direction of retreating from the image forming position of the control grid.

Since the toner transfer member is to be interposed in the narrow slit space between the control grid and the back electrode, it is premised that it is a thin layer body, and the toner adhered to the control grid is Since the thin layer body is charged due to the rubbing, at least the surface of the thin layer body is covered with an insulating layer, so that the toner carrying capacity is increased and the toner scattering can be prevented during the movement of the thin layer body. ..

Such a thin layered body is formed as an endless winding body having a plane portion parallel to the control grid on the side facing the control grid, more specifically, in the form of a belt or a flat plate. Good to do. That is, since the thin layer body has a plane portion parallel to the control grid, the electric field, the magnetic field, and other physical acting forces applied to the thin layer body should be uniformly applied to the entire image forming area of the control grid. Therefore, the toner adhering to the control grid can be removed accurately and surely without generating residual toner.

Further, the physical acting force is not particularly limited and may be adhered by utilizing, for example, a developing bias, but more preferably, the toner is surely trapped from the control grid side at the image forming position, and At the position where the thin layer body is retracted from the image forming position, the acting force is released and the adhered toner is easily removed to the toner containing portion side, and further, the acting force does not have an adverse effect at the time of image formation. Need to be considered. In the image forming apparatus using the magnetic toner, it is possible to achieve the above-mentioned effects.
We propose a magnetic field generating means that is formed by spirally winding an electromagnet or conducting wire that can be turned off.

In this case, the magnetic field generating means may be formed by an electromagnet. However, by winding the conducting wire in a spiral shape, the thin layer body and the magnetic field generating means can be integrated, and accurate control is possible. In addition, it is easy to adjust the magnetic force that can attract the toner by adjusting the winding amount, and the toner attached to the control grid can be removed without affecting the toner carried on the developing roller. It can be reliably transferred to the thin layer side. It is difficult to completely wipe off the electrostatically adsorbed toner only by the magnetic field generating means. Therefore, in the present invention, rubbing means for rubbing the surface of the control grid adjacent to the magnetic field generating means is provided on the thin layer body.

As a result, since the toner adhering to the control grid can be swept away by the rubbing means, the toner can be magnetically adsorbed on the thin layer body, so that the toner is scattered even if the rubbing means is used. Further, the paper dust and the like can be removed together with the magnetic toner by the rubbing, and the cleaning effect of the control grid is further improved.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment of the present invention will be described in detail below as an example with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention thereto, but are merely illustrative examples. Not too much. Figure 1
1 shows a main part configuration of an image forming apparatus according to an embodiment of the present invention, including a developing roller 1 having a toner container 10 in order from the top, a flat mesh control grid 2 having toner passage holes 2a formed in a matrix, The control grid 2 comprises a back electrode 3 arranged below the image forming area, and a belt body 4 arranged so as to pass through the upper surface of the back electrode 3 and circulate therebelow. The developing roller 3 is grounded, and a developing bias power source 12 is applied to the back electrode 3 via a switch 11. A control voltage 13 for electromagnetically opening and closing the toner passage hole 2a can be applied to the control grid 2.

Next, the structure of the belt body, which is the main part of the present invention, will be described. The belt body 4 is formed of an insulating resin film having a high tensile strength, and a pair of shaft rollers 21 supporting the belt body 4 are arranged at a position lower than the back surface electrode 3 so that the belt body 4 and the back surface electrode 3 are connected to each other. It is possible to circulate by supporting at three points, so that the belt body 4 can circulate while being stretched on the surface of the back electrode 3. In addition, the residual toner storage container 2 is provided below the peripheral circuit of the belt body 4.
2 is provided, and the toner dropped to the belt body 4 side at the facing position of the control grid 2 by the cleaning process described later, and the toner attached to the belt body 4 is removed by a scraper,
A brush or other toner scraping member 23 is used to be swept to the storage container 22 side.

Reference numeral 24 denotes a charge eliminating brush which is arranged so as to be able to face the shaft roller 21 on the downstream side in the belt moving direction at the sweeping position.
It is configured to be movable to a position facing the control grid 2.

Next, the operation of this embodiment will be described. During image operation, by applying a pulsed control voltage to the control grid 2 while applying a developing bias to the back electrode 3, the developing electric field acting on the matrix-shaped toner passage holes 2a is made to correspond to image information. The toner carried on the developing roller 1 is adhered to the recording material side through the toner passage hole 2a on the recording paper inserted on the surface of the back electrode 3 by selectively blocking or conducting. , Predetermined image formation is performed.

Then, as shown in the time chart of FIG. 2, after the printing operation is continued for a predetermined time or each time the printing operation of one sheet is completed, the belt body 4 starts to rotate and the control grid 2 is controlled. Stop applying voltage. As a result, since the toner passage hole 2a is opened electromagnetically, by applying a pulsed developing bias from the back electrode 3 side in this state, the toner attached around the toner passage hole 2a is removed. It is transferred onto the belt body 4 stretched on the surface of the back electrode 3. Since the toner is charged by rubbing against the control grid 2,
While being carried by the insulative belt body 4, the belt body 4 and the belt body 4 are circulated to the lower surface side of the peripheral circuit, and then are wiped off to the storage container side using the toner scraping member 23. After the cleaning, the surface of the belt body 4 is neutralized by the static elimination brush, and when the static elimination unit moves to the position facing the control grid 2, the circulation is stopped. After that, the print operation is restarted and the above operation is repeated.

FIG. 4 shows a plan view of a belt body 40 according to another embodiment of the present invention, in which a large number of winding portions 41 in which a conductor wire is spirally wound in a rectangular shape along the longitudinal direction are provided. In the arrayed state, the upper and lower surfaces are sandwiched by insulating films, and one end of the winding 41 is pulled out and connected to the electrode portions 42 exposed at the side edges of the film. Further, bristles 42 are planted along the lateral direction between adjacent windings on the outer peripheral surface of the belt 40, and the control grid 2 is provided via the bristles 42.
The surface can be rubbed.

As shown in FIG. 3, the belt body 40 is stretched and supported by a pair of rotating rollers 31 so that the slit space between the control grid 2 and the back electrode 3 can be circulated substantially parallel to each other. As shown in the drawing, a leaf spring-shaped lead electrode 32 in contact with the electrode portion 41 is arranged on the side of the belt body 40 corresponding to the image forming area of the control grid 2, and connected to the power source 39 via the lead electrode 32. The switch 33 is connected. A toner storage portion 34 is arranged below the belt body 40 so that the toner adhering to the belt body 40 can be swept away by the brush 35, and a mesh-shaped paper is provided on the outlet side of the storage container 34. A powder separation filter 36 is provided, and after removing the paper powder by the filter 36, it can be returned to the developing container 10 again. The belt body 40 located on the back side of the belt body 40
May be arranged in contact with the belt body 40, or may be arranged in parallel in a non-contact state.

Next, the operation of this embodiment will be described in detail. The control voltage is applied to the control grid 2 after the above-described printing operation is continued for a predetermined time or after the printing operation of one sheet is completed in the state where the belt body 40 is not rotated and the switch 33 of the winding 41 is turned off. And the switch 33 of the winding 41 is turned on to turn on the belt body 40.
The orbital drive of is started. As a result, the toner passage hole 2a is electromagnetically opened, and a magnetic attraction force is exerted on the side of the belt body 40 facing the grid 2. By rotating the belt body 40 in this state, the flocked hair 42 is controlled by the control grid. After rubbing the two surfaces to mechanically remove toner, paper dust, and the like, these are attracted to the surface of the belt body 40 by the magnetic attraction force of the winding wire 41.

Then, when the belt body 40 comes out of the image forming area due to the subsequent circulation, the contact with the lead electrode 32 is released and the magnetic attraction force is released.
Since 0 is an insulating material, it circulates while maintaining the toner carrying state, circulates to the lower surface side of the peripheral circuit, and then is wiped off to the storage container 34 side using the brush 32. After the cleaning, the paper dust separating filter 36 removes the paper dust on the outlet side of the storage portion 34, and then the fan 37 is used to return the paper dust to the developing container 10 side. After that, when the belt body 4 makes a predetermined revolution, the revolution is stopped and the printing operation is restarted. After that, the above operation is repeated.

[0024]

As described above, according to the present invention, even if the control grid is clogged, it can be removed smoothly without complicating the maintenance work, and thus the image can be precisely processed without causing image distortion. It also enables clear image formation. Further, even if the adsorbed toner of the control grid is dropped onto the back electrode side, cleaning can be smoothly performed without contaminating the recording paper or the like.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a time chart diagram showing the operation of the image forming apparatus shown in FIG.

FIG. 3 is a configuration diagram of main parts of an image forming apparatus according to another embodiment of the present invention.

4 is a plan view of a belt body used in the apparatus of FIG.

FIG. 5 is an overall configuration diagram of an image forming apparatus according to a conventional technique.

[Explanation of reference numerals] 1 toner carrier 2 control grid 3 back electrodes 4, 40 belt body 41 magnetic field generating means (winding) 41 magnetic field generating means (winding)

 ─────────────────────────────────────────────────── ─── Continued front page (72) Masayuki Tone 2-14-9 Tamagawadai, Setagaya-ku, Tokyo Kyocera Corporation Tokyo Yoga Works (72) Inventor Akira Sato 2-14 Tamagawadai, Setagaya-ku, Tokyo No. 9 Kyocera Corporation Tokyo Yoga Works

Claims (4)

[Claims] 1. A toner carrier and a back electrode, on the surface of which a recording material is movable, are arranged facing each other through a control grid in which a group of electromagnetically openable and closable toner passage holes are arranged in a substantially matrix. In the image forming apparatus, a thin layer body having an insulating layer at least on the surface is interposed between the control grid and the back electrode, and the toner adsorbed on the control grid is transferred onto the thin layer body by a physical force. After that, the image forming apparatus is configured such that the thin layer body can be moved in a direction of retracting from the image forming position of the control grid. 2. The image forming apparatus according to claim 1, wherein the thin layer body is formed of an endless revolving body having a plane portion parallel to the control grid on the side facing the control grid. 3. The image forming apparatus according to claim 1, wherein a magnetic toner is used, the thin layer body is provided with a magnetic field generating means that is generated only during non-image formation, and the magnetic field is provided at least at a position facing the control grid. The image forming apparatus according to claim 1, wherein the generation of the magnetic field can be stopped at a predetermined position where the occurrence of the magnetic field occurs and the image forming position is retracted. 4. The image forming apparatus according to claim 3, wherein rubbing means for rubbing the surface of the control grid adjacent to the magnetic field generating means is provided on the thin layer body.