JP3023228B2 - 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 and the like, 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 electrode 52; a control circuit 55 for generating a signal corresponding to image information; a driving circuit 56 for switching the control grid 53 based on the signal;
A support plate for positioning and fixing the back electrode 52 at a predetermined position via a spring 57a biased from the bottom surface.

[0003] The operation of such an apparatus will be briefly described below. The magnetic toner contained in the toner container 51 is regulated in layer thickness by a doctor blade 51b and then controlled by a control grid 5a.
The developing electric field is applied between the developing roller 50 and the rear electrode 52 by a power supply circuit 54 provided on the rear electrode 52 side at the developing position. In this state, the control grid 53 is controlled to be energized in the X-Y axis directions based on signals from the control circuit 55 and the drive circuit 56, so that the matrix-shaped toner passage holes 5 are formed.
The recording field 58 is inserted into the surface of the back electrode 52 in synchronism with the image information by selectively blocking or conducting the development electric field acting on the 3a in accordance with the image information. 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.

[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. toner is Ru generally at the transition downstream side <br/> Oh, it be pulled back it in the opposite direction because it is adsorbed to the back surface electrode side is not a medium people easily. 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 peel off the toner adsorbed by the frictional charging by only the electric field of the developing bias. Therefore, a cleaning method of blowing off the control grid with air or the like is being studied. However, the configuration using air requires a blowing pressure higher than the electrostatic attraction force of the toner. As a result, the size of the air generating device is increased and the cost is increased.

In view of the drawbacks of the prior art, the present invention smoothly removes the control grid even if it becomes clogged without complicating the maintenance work, thereby providing a precise image without disturbing the image. It is another object of the present invention to provide an image forming apparatus capable of forming a clear and clear image.

[0009]

According to the present invention, the toner adsorbed on the control grid by applying an electric field, a magnetic field or a mechanical action force falls on the back electrode side, not on the developing roller side (note that the back electrode does not necessarily fall downward). The term "transfer" is used in the claims as it is not necessarily located.) However, the present invention is characterized in that the dropped toner is not formed on the recording paper but between the control grid and the back electrode. Before
The recording material is placed on a thin layer interposed separately from the recording material.
The first feature is that the transfer is performed after the print operation is completed . The second feature is that, after transferring the toner onto the thin layer body, the thin layer body is configured to be movable in a direction to retreat from an image forming position of the control grid.

[0010] The Ususotai is a thin layer for those to be interposed in a narrow slit space between the control grid back electrode
It is premised that the toner adhered to the control grid is charged by its rubbing, so that at least the surface of the thin layer body is coated with an insulating layer,
The toner carrying capacity is increased, so that toner scattering during the movement of the thin layer body can be prevented.

[0011] Such a thin layered body is formed in an endless circulating body having a plane portion parallel to the control grid on a side facing the control grid, more specifically, in a belt shape or a flat disk shape. Good to do. That is, since the thin layer body has a plane portion parallel to the control grid, the electric field, magnetic field, and other physical acting forces applied to the thin layer body uniformly act on the entire image forming area of the control grid. Thus, the toner adhering to the control grid can be accurately and reliably removed without generating residual toner.

The physical acting force is not particularly limited. For example, the physical acting force may be applied by using a developing bias or the like. More preferably, the toner is more reliably captured from the control grid side at the image forming position, and The acting force is released at the position where the thin layer member is retracted from the image forming position, the adhered toner is easily removed to the toner storage portion side, and the acting force does not adversely affect the image formation. It is necessary to take care. In an image forming apparatus using a magnetic toner, the ON /
The present invention proposes a magnetic field generating means formed by spirally winding an electromagnet or a conductor that can be turned off.

In this case, the magnetic field generating means may be formed by an electromagnet. However, by forming a conductive wire by winding it in a spiral shape, the thin layer body and the magnetic field generating means can be integrated, and accurate control can be achieved. And it is easy to adjust the magnetic field force capable of attracting the toner by adjusting the winding amount, thereby preventing the toner adhered to the control grid from affecting the toner carried on the developing roller. It can be surely transferred to the thin layer side. It is difficult to completely remove the electrostatically attracted toner only by the magnetic field generating means. The present invention is to dispose the rubbing means for rubbing the control grid surface to be adjacent to the magnetic field generating means.

As a result, after the toner adhering to the control grid is swept down by the rubbing means, it can be magnetically adsorbed on the thin layer body. Also, paper dust and the like can be removed together with the magnetic toner by the above-mentioned rubbing, and the cleaning effect of the control grid is further improved.

[0015]

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 configuration of a main part of an image forming apparatus according to an embodiment of the present invention. A developing roller 1 having a toner container 10 sequentially from above, a control grid 2 of a flat mesh shape having toner passing holes 2a formed in a matrix form, It comprises a back electrode 3 arranged below the image forming area of the control grid 2, and a belt body 4 arranged so as to pass through the upper surface of the back electrode 3 and go around the lower area. The developing roller 1 is grounded, and a power source 12 for developing bias is applied to the back electrode 3 via a switch 11. The control grid 2 is configured to be able to apply a control voltage 13 for electromagnetically opening and closing the toner passage hole 2a.

Next, the structure of the belt body as a main part of the present invention will be described. The belt member 4 is formed of an insulating resin film having a large tensile strength. A pair of shaft rollers 21 supporting the belt member 4 are disposed below the back electrode 3, and are disposed between the back electrode 3 and the shaft roller 21. The belt member 4 can be circulated by three-point support so that the belt member 4 can be circulated while being stretched on the surface of the back electrode 3. A residual toner container 2 is located at a position below the peripheral circuit of the belt member 4.
2 is disposed, and in a cleaning process described later, the toner that has fallen toward the belt body 4 at a position facing the control grid 2 and adhered to the belt body 4 is removed by a scraper,
A brush or other toner scraping member 23 is used so that it can be swept down to the storage container 22 side.

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

Next, the operation of the embodiment will be described. At the time of image operation, by applying a pulse-like control voltage to the control grid 2 with a development bias applied to the back electrode 3, the development electric field acting on the matrix-like toner passage holes 2a is made to correspond to image information. The toner carried by the developing roller 1 adheres to the recording material side through the toner passage hole 2a on the recording paper inserted into the surface of the back electrode 3 by selectively blocking or conducting. , A predetermined image formation is performed.

As shown in the time chart of FIG. 2, after the printing operation is continued for a predetermined time or each time one printing operation is completed, the belt body 4 starts to rotate and the control grid 2 is controlled. Stop applying voltage. As a result, the toner passage hole 2a is electromagnetically opened. In this state, by applying a pulse-like developing bias from the back electrode 3 side, the toner adhering around the toner passage hole 2a is removed. The transfer to the belt body 4 stretched on the surface of the back electrode 3. Since the toner is charged by rubbing with the control grid 2,
After the belt member 4 is circulated to the lower surface side of the peripheral circuit while being carried on the insulating belt member 4, the belt member 4 is swept down to the storage container 22 side using the toner scraping member 23. Then, after the sweeping, the surface of the belt body 4 is neutralized by the neutralizing brush 24 , and then the static eliminator is controlled by the control grid 2.
When the robot moves to the position facing the above, the circling is stopped. Thereafter, the printing 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 plurality of winding portions 41 are formed by spirally winding conductive wires in the same direction in a longitudinal direction. both the upper and lower both sides while sequence pinched by an insulating film, is pulled out the winding portion 41 at one end to each electrode portion 44 to expose people connected to the film side edge. A bristle 42 is implanted along the lateral direction between adjacent windings on the outer peripheral surface of the belt body 40, and the surface of the control grid 2 is slidable through the bristle 42.

As shown in FIG. 3, the belt body 40 is not shown in FIG. 3, but can circulate in a substantially parallel slit space between the control grid 2 and the back electrode 3 shown in FIG. And a pair of rotating rollers 31 so as to be stretched and supported, and the electrode is provided on the side of the belt body 40 corresponding to the image forming area of the control grid 2 (see FIG. 1).
A leaf spring-shaped lead electrode 32 that is in contact with the portion 44 is disposed,
The switch 33 is connected to the power supply 39 via the lead electrode 32. A toner storage container 34 is disposed below the belt body 40 so that the toner attached to the belt body 40 can be swept off by a brush 35. A powder separation filter 36 is provided, and after paper dust is removed by the filter 36, the filter can be returned to the toner container 10 again. The back electrode 3 located on the back side of the belt body 40 is
It 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 the present embodiment will be described in detail. The control grid 2 (see FIG. 1) after the above-described printing operation is continued for a predetermined period of time with the belt body 40 stopped rotating and the switch 33 of the winding unit 41 turned off, or after one printing operation is completed . The application of the control voltage to the winding unit 41 is stopped, and the switch 33 of the winding unit 41 is turned on to start driving the belt body 40 to rotate. As a result,
The toner passage hole 2a is opened electromagnetically and the control
Magnetic attraction acts on the side of the belt body 40 facing the lid 2, and in this state, by rotating the belt body 40, the flocking 42 rubs the surface of the control grid 2, and the toner or paper dust is mechanically formed. After these are removed, these are attracted to the surface of the belt body 40 by the magnetic attraction of the winding part 41 .

When the belt body 40 deviates from the image forming area due to the subsequent rotation, the contact with the lead electrode 32 is released and the magnetic attraction is released.
0 in order to be insulating, circulates while maintaining the toner carrying state, after passing around to the divider lower side, Bra
The toner is swept down to the toner storage container 34 side by using a web 35 . After the cleaning, the toner container
After the paper dust is removed by the paper dust separation filter 36 at the outlet 34, the paper dust is returned to the toner container 10 side using the fan 37. Thereafter, when the belt body 4 has rotated a predetermined amount, the rotation is stopped and the printing operation is restarted. Thereafter, the above operation is repeated.

[0024]

As described above, according to the present invention, even if the control grid is clogged, the control grid can be smoothly removed without complicating the maintenance work. In addition, clear images can be formed. Further, even if the toner adsorbed on the control grid is dropped on the back electrode side, the cleaning can be performed smoothly without contaminating the recording paper or the like.

[Brief description of the drawings]

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

FIG. 2 is a time chart illustrating an operation of the image forming apparatus illustrated in FIG. 1;

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

FIG. 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 the related art.

[Explanation of symbols]

 1Developing roller (toner carrier)  2 control grid 3 back electrode 4, 40 belt body 41Winding part (magnetic field generating means)

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Akira Sato 2-14-9 Tamagawadai, Setagaya-ku, Tokyo Kyocera Corporation Tokyo Yoga Office (56) References JP-A-3-168767 (JP, A) 58-104769 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B41J 2/385

Claims (4)

(57) [Claims] 1. A toner carrier and a back electrode on which a recording material can move on a front surface side are arranged face-to-face via a control grid in which toner passage holes that can be opened and closed electromagnetically are arranged in a substantially matrix form. and between the back electrode and the control grid in an image forming apparatus comprising, together with at least the surface to be separately interposed between the recording material thin layer body composed of an insulating layer, after printing operation is completed to the recording medium, wherein After the toner adsorbed on the control grid is transferred onto the thin layer body by a physical action force, the thin layer body is configured to be movable in a direction to retract from an image forming position of the control grid. Image forming device. The method according to claim 2, wherein the thin layer body, on the side facing the control grid, said control grid and an image forming apparatus according to claim 1, wherein the formation of an endless circulation member formed with a plane parallel sites. 3. The image forming apparatus according to claim 1, wherein a magnetic field generating means which is generated only during non-image formation is provided in said thin layer body, and said magnetic field is generated at least at a position facing said control grid. 2. The image forming apparatus according to claim 1, wherein generation of said magnetic field is stopped at a predetermined location retracted from said image forming position. Wherein said magnetic field generating means and the image forming apparatus according to claim 3, wherein the disposing the rubbing means for rubbing the control grid surface to be adjacent.