JPH11334134A - Image formation apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image formation apparatus that is equipped with a means for eliminating problems such as a decrease in a mirror image force brought about when a quantity of a developer required to be cleaned also because of a cleaning electric field by an AC increases, etc. SOLUTION: A potential is impressed to an electrode 27 of a control electrode 26 from a control power source part 31, thereby controlling passing of a developer 21 through a gate 29 from a hold body 22. The developer flying towards an opposite electrode 25 forms an image to a surface of a recording medium 5. In this case, a dielectric layer is set at the side of the opposite electrode 25 of the control electrode 26 so as to hold a relationship Fc<Fb wherein Fc is an adhesion force of the developer adhering to a surface of the control electrode 26 at the side of the opposite electrode 25 and Fb is an adhesion force of the developer adhering to the opposite electrode 25. Moreover, a cleaning electric field is applied between the opposite electrode 25 and the control electrode 26, which is changed in field direction by an oscillation component and satisfies a relationship Fc<FE<Fb wherein FE is an electric force applied from the cleaning electric field to the developer adhering to the control electrode 26. The developer adhering to the control electrode 26 is accordingly removed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a printing section of a digital copying machine and a facsimile apparatus, a digital printer, a plotter, and the like, and an image forming apparatus for forming an image on a recording medium by flying a developer. It is about.

[0002]

2. Description of the Related Art In recent years, as an image forming apparatus for outputting an image signal as a visible image on a recording medium such as paper, for example, an electric field is applied to a charged particle by applying an electric field as disclosed in Japanese Patent Application Laid-Open No. Hei 4-286662. The charged particles heading toward the recording medium are controlled by changing the potential applied to a control electrode having a plurality of through holes arranged in the flight path, and an image is directly formed on the recording medium by adhering to the recording medium. An image forming apparatus to be formed has been proposed. As a method for cleaning the charged particles attached to the control electrode, Japanese Patent Application No.
Although a method like -201181 has been proposed, it causes the following problems.

[0003]

An image forming apparatus of the type typified by the above-mentioned prior art uses control means for controlling the passage of charged particles through the gate. By controlling the electric field formed between the recording medium and the carrier, whether or not the toner can fly is controlled, and the toner is caused to reach the surface of the paper as a recording medium by the strong electric field formed by the counter electrode to form an image. In this type of image forming apparatus, it is inevitable that toner adheres to the control electrode. The toner adheres to the inside of the gate through which the toner passes and the counter electrode side of the control electrode, in addition to the surface of the control electrode facing the carrier.

Various problems occur due to the adhesion of the toner. For example, not only the potential applied to the control electrode by the toner is shielded, but also the potential of the control electrode changes due to the potential due to the electric charge of the toner. No toner flight can be obtained. If good toner flight cannot be obtained, the diameter of the formed dots will change or the dot density will not be appropriate, which will easily cause image deterioration. Further, in such a state, a desired electric field cannot be formed around the gate, and the flying trajectory of the toner greatly changes from a good state, making it difficult to control the flying trajectory of the toner. In a state where it is difficult to control the flight trajectory of the toner, it is difficult to guide the toner to a predetermined position, and for example, the scattering of the toner easily occurs, and the quality of the formed dots is deteriorated. Thus, the dot diameter and the dot density change as described above occurs. In such a state, it is difficult to form a desired halftone, and in a color image forming apparatus, it is difficult to achieve good color reproduction. Further, if toner adheres to the control electrode inside the gate, which is a toner passage, for example, it becomes difficult for the toner to pass through the gate, and a predetermined amount of toner cannot pass through the gate, thus causing the above-described problem. .

Further, the flying locus of the flying toner changes due to the contact between the passing toner and the toner attached to the inside of the gate or the electric field formed by the charge of the toner attached to the inside of the gate. Similarly, the trajectory of the toner cannot be satisfactorily controlled, causing the same problem as described above. In addition, if the toner adhesion to the control electrode deteriorates, the gate will eventually be clogged, and the toner will not physically pass, which will easily cause image loss.

Further, when a part of the sheet comes into contact with the control electrode due to wrinkles or curls of the sheet, for example, the adhered toner adheres to the sheet due to the toner adhering to the counter electrode side of the control electrode. In addition to the generation of dirt, a defect that disturbs the formed image occurs. As described above, since the adhesion of the toner to the control electrode is inevitable and causes various problems, the toner attached to the control electrode must be cleaned.

In the above prior art, an AC potential is applied to a control electrode to form a cleaning electric field composed of an AC electric field having almost no DC component between the control electrode and the counter electrode, and toner is removed by a difference in mirror image force. This is a configuration for selecting the direction in which to perform. However, as the amount of adhesion on the control electrode increases, the amount of toner to be removed necessarily increases. As the amount of toner to be removed increases, the collected toner on the counter electrode adheres in multiple layers, and the adhered toner on the second and third layers moves between the control electrode and the counter electrode because the effect of the image force is lost. The toner is not easily collected by the counter electrode.

Further, at the same time when the cleaning electric field is turned off, the toner adhered to the counter electrode partially flies back to the control electrode.
The toner adheres to the vicinity of the wall surface of the hole of the gate, a hole clogging occurs due to an increase of the toner adhered to the wall surface, a reciprocating area expands while the toner reciprocates between the control electrode and the counter electrode, and the toner scatters outside the printing area. Unless the toner is a magnetic toner that works, the toner cannot be moved back to the toner carrier without using a contact member such as a bristle brush or a blade that causes wear on the electrode surface (Japanese Patent Laid-Open No. Hei 7-32641). The control electrode dielectric surface and its surroundings are frictionally charged with the toner due to the reciprocation of the toner, and if a conductive film is provided to release the charge, the adhesion of the toner will increase and the cleaning performance will deteriorate, causing the generation of a high-voltage oscillating electric field. However, there is a problem that a high-speed response expensive power supply and a dangerous current need to flow.

[0009] The present invention relates to the prior art AC
It is an object of the present invention to provide an image forming apparatus provided with means for solving the above-mentioned problem that occurs when the amount of developer that needs to be cleaned also increases due to the cleaning electric field caused by the above.

[0010]

According to a first aspect of the present invention, there is provided an image forming apparatus comprising: a supply unit having a carrier for supporting a developer; a supply unit configured to supply the developer from the carrier; An electrode, a high-voltage power supply for supplying a voltage for generating a high potential difference between the counter electrode and the carrier, and a gate disposed between the carrier and the counter electrode and serving as a developer passage portion , A control electrode provided around the gate on the insulating substrate, and control circuit means for controlling a potential state of the control electrode, wherein the control electrode means A predetermined potential is applied to control the passage of the developer from the supply means through the gate, and the developer which passes through the gate and flies toward the counter electrode forms an image on the surface of the recording medium. Image forming apparatus, wherein the control electrode A dielectric material is provided on the control electrode side of the counter electrode so that the relationship between the adhesive force Fc of the developer adhered to the surface of the counter electrode and the adhesive force Fb of the developer adhered to the counter electrode is Fc <Fb. A cleaning electric field in which a layer is provided and the direction of the electric field is changed by an oscillating component between the counter electrode and the control electrode, wherein the cleaning electric field applies an electric force FE to the developer adhered to the control electrode; And applying a cleaning electric field so as to make the relationship of Fc Fc <FE <Fb to remove the developer adhering to the control electrode, and whether the DC component of the cleaning electric field is very small with respect to the vibration component. Or in an image forming apparatus with an electric field having no DC component,
At the end of the operation of applying the cleaning electric field, the last electric field direction ends in a direction in which the developer adhered to the surface of the control electrode facing the counter electrode is directed toward the counter electrode.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the cleaning electric field is applied in a direction in which the developer on the control electrode attached to the surface of the counter electrode is directed toward the counter electrode. The developer is removed by maintaining the state of applying the developing agent on the counter electrode.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, when the cleaning electric field is formed,
The relationship between the effective working surfaces of the control electrode and the counter electrode is offset from the parallel arrangement.

According to a fourth aspect of the present invention, in the image forming apparatus according to the third aspect, the counter electrode has an electrode area having an area larger than the printing area, and the counter electrode and the control electrode are connected to each other. The distance between the print area and the print area is smaller than that in the print area.

According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects, a high-resistance film is provided on a surface of the dielectric layer outside a printing area, and a resistance of the high-resistance film is reduced. A time constant determined by the capacitance between the high-resistance film and the counter electrode is larger than the oscillation period of the cleaning electric field.

According to a sixth aspect of the present invention, in the image forming apparatus according to the first or second aspect, an electric field between the carrier carrying the developer and the control electrode as the cleaning electric field is applied to the surface of the counter electrode. This is a direction in which the adhered developer is directed toward the developer carrier, and the equipotential surface of the gate portion is made convex toward the counter electrode.

According to a seventh aspect of the present invention, in the image forming apparatus according to any one of the first to sixth aspects, the distance between the counter electrode and the control electrode during the formation of the cleaning electric field is larger than that during printing, and The present invention is characterized in that the potential difference between the counter electrode and the control electrode is made larger than at the time of printing.

According to a further aspect of the present invention, there is provided a supply means having a carrier for carrying a developer, for supplying a developer from the carrier, a counter electrode disposed opposite to the carrier, and a counter electrode. High-voltage power supply means for supplying a voltage for generating a high potential difference between the carrier and the carrier; and an insulating member provided with a gate disposed between the carrier and the counter electrode and serving as a developer passage portion. A substrate, a control electrode provided around the gate on the insulating substrate, and control circuit means for controlling a potential state of the control electrode, and applying a predetermined potential to the control electrode by the control circuit means An image forming apparatus that controls the passage of the developer from the supply unit through the gate, and the developer that passes through the gate and flies toward the counter electrode forms an image on the surface of a recording medium. The counter electrode is divided into a plurality of divided electrodes. Vital is that characterized by the removal of the developer adhering to the control electrode by forming a uniform electric field between said segmented electrode are approximated to the divided electrodes to each other.

According to a ninth aspect of the present invention, in the image forming apparatus according to the eighth aspect, different voltages are alternately applied to the divided electrodes.

According to a tenth aspect of the present invention, in the image forming apparatus of the eighth or ninth aspect, the counter electrode is a divided electrode roll, and a cleaning electric field is formed on the electrode while rotating the divided electrode roll. It is a characteristic.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (Embodiment 1) The components of an image forming apparatus according to the present embodiment will be outlined with reference to FIG. In the following description, an image forming apparatus having a configuration corresponding to a negatively charged toner will be described in detail. However, when a positively charged toner is used, the polarity of each applied voltage is appropriately set accordingly. do it. In this embodiment, as shown in FIG.
And an image forming unit 1 having the following. The image forming unit 1 visualizes an image corresponding to an image signal on a sheet as a recording medium using toner as a developer. In other words, the present image forming apparatus directly forms an image on paper by controlling the flying of the toner based on an image signal while causing the toner to fly and adhere to the paper.

On the side of paper entering the image forming section 1,
A paper feeding device 10 is provided. The paper feeding device 10 includes a paper cassette 4 that stores paper 5 as a recording medium, a pickup roller 6 that feeds the paper 5 from the paper cassette 4, a paper feed guide 7 that guides the supplied paper 5, and predetermined paper. It consists of a pair of registration rollers 125 for giving a transport speed. Further, the paper feeding device 10 includes a paper feeding sensor (not shown) for detecting that the paper 5 has been supplied. The pickup roller 6 is driven to rotate by a driving device (not shown).

On the paper output side of the sheet from the image forming section 1, a fixing section 11 for fixing the toner image formed on the sheet 5 in the image forming section 1 to the sheet 5 by heating and pressing is provided. Is provided. The fixing unit 11 includes the heating roller 1
2, a heater 13, a pressure roller 14, a temperature sensor 15, and a temperature control circuit 80. The heating roller 12
For example, it is made of an aluminum tube having a thickness of 2 mm. The heater 13 includes, for example, a halogen lamp, and is built in the heating roller 12. The pressure roller 14 is made of, for example, a silicone resin. The heating roller 12 and the pressure roller 14 provided opposite to each other are pressurized with springs or the like (not shown) at both ends of each shaft so as to be able to press the paper 5 therebetween.
g load is applied. The temperature sensor 15 measures the temperature of the surface of the heating roller 12. The temperature control circuit 80
The main controller controls the ON / OFF of the heater 13 based on the measurement result of the temperature sensor 15 to maintain the temperature of the surface of the heating roller 12 at, for example, 150 ° C.

The fixing section 11 has a paper discharge sensor (not shown) for detecting that the paper 5 has been discharged.
The materials of the heating roller 12, the heater 13, the pressure roller 14, and the like are not particularly limited. Further, the temperature of the surface of the heating roller 12 is not particularly limited. Further, the fixing unit 11 may be configured to fix the toner image by heating or pressing the paper 5. Although not shown, on the paper output side of the paper from the fixing unit 11, a paper discharge roller for discharging the paper 5 processed by the fixing unit 11 onto a paper discharge tray, and a paper discharge for receiving the discharged paper 5 A tray is provided. The above heating roller 1
2. The pressure roller 14 and the paper discharge roller are rotationally driven by a driving device (not shown).

The toner supply unit 2 of the image forming unit 1 includes a toner storage tank 2 in which a toner 21 as a developer is stored.
A toner carrier 22 as a cylindrical carrier (sleeve) for carrying the toner 21 by magnetic force, and a toner storage tank 20 are provided inside the toner carrier 22 to charge the toner 21 and to provide an outer periphery of the toner carrier 22. The doctor blade 23 regulates the thickness of the toner layer carried on the surface.
The doctor blade 23 is provided on the upstream side in the rotation direction of the toner carrier 22 so that the distance from the outer peripheral surface of the toner carrier 22 is, for example, 60 μm.
The toner 21 is, for example, a magnetic toner, and is provided with a negative charge by the doctor blade 23.
The distance between the doctor blade 23 and the toner carrier 22 is not particularly limited.

The toner carrier 22 is driven by a driving device (not shown), and rotates in the direction of arrow A in the figure, for example, at a speed of 80 mm / sec on the surface. Further, the toner carrier 22 is grounded, and magnets (not shown) are arranged inside the toner carrier 22 at a position facing the doctor blade 23 and a position facing a control electrode 26 (described later). Thus, the toner carrier 22 can carry the toner 21 on its outer peripheral surface. Further, the toner 21 carried on the outer peripheral surface of the toner carrier 22 forms ears at positions corresponding to the above positions on the outer peripheral surface. The rotation speed of the toner carrier 22 is not particularly limited. Further, instead of supporting the toner 21 by a magnetic force, the toner carrier 22 may be configured to support the toner 21 by an electric force or an electric force and a magnetic force.

The printing unit 3 of the image forming unit 1 is made of, for example, an aluminum plate having a thickness of 1 mm, and has a counter electrode 25 facing the outer peripheral surface of the toner carrier 22 and a high-voltage power supply for supplying a high voltage to the counter electrode 25. 30, a cleaning brush 25b (details will be described later) as a cleaning means for cleaning the counter electrode 25, and a control provided between the driving means 25d (details described later) of the cleaning brush 25b and the toner carrier 22. The apparatus includes an electrode 26, a paper guide 128, and a suction device 92 that suctions air so that the paper 5 does not contact the control electrode 26. In the suction device 92, a chamber 96, a fan 93 for reducing the pressure in the chamber, an intake port 94 for sucking the paper 5, paper guides 124 and 126, and a counter electrode 25 are arranged.

The counter electrode 25 is connected to the toner carrier 22.
Is provided such that the distance from the outer peripheral surface thereof is, for example, 1 mm. The suction device 92 reduces the pressure in the chamber 96 by the fan 93, and the suction port 94 is reduced by the reduced pressure.
The sheet 5 is sucked by air. Further, a high voltage of, for example, 2 kV is applied to the counter electrode 25 by a high voltage power supply (control means) 30 at the time of printing.
That is, between the counter electrode 25 and the toner carrier 22,
An electric field necessary for causing the toner 21 carried on the toner carrier 22 to fly in the direction of the counter electrode 25 is applied by the high voltage applied from the high voltage power supply unit 30. The distance between the counter electrode 25 and the toner carrier 22 is not particularly limited. Further, the voltage applied to the counter electrode 25 is not particularly limited.

Although not shown, the present image forming apparatus
As a control circuit, a main control unit that controls the entire image forming apparatus, an image processing unit that converts the obtained image data into a format of image data to be printed, an image memory that stores the converted image data, An image forming control unit that converts image data obtained from the image processing unit into image data to be provided to the control electrode 26; The above control electrode 2
Numeral 6 is two-dimensionally spread parallel to the counter electrode 25 and opposed to the counter electrode 25, and has a structure capable of passing toner from the toner carrier 22 in the direction of the counter electrode 25. The electric field applied to the surface of the toner carrier 22 changes according to the potential supplied to the control electrode 26,
The flying of the toner 21 from the toner carrier 22 to the counter electrode 25 is controlled.

The control electrode 26 is connected to the toner carrier 22
Is provided so that the distance from the outer peripheral surface thereof is, for example, 100 μm, and is fixed by a support member (not shown). As shown in FIG. 2, the control electrode 26 includes an insulating substrate 26a, a high-voltage driver (not shown), and an independent ring-shaped conductor, that is, a ring-shaped electrode 27. The substrate 26a is made of, for example, a polyimide resin and has a thickness of 25 μm. Further, a hole to be a gate 29 described later is formed in the substrate 26a. The ring-shaped electrode 27 has a thickness of 18 μm, for example.
And is provided around the hole, and is arranged according to a predetermined arrangement. The opening of each hole has a diameter of, for example, 160 μm, and serves as a passage for the toner 21 flying from the toner carrier 22 to the counter electrode 25. Hereinafter, this passing portion is referred to as a gate 29. Further, a shield electrode 39 which is made of one electrode and is in contact with the control electrode 26 is disposed on the side of the counter electrode 25 of the control electrode 26. The distance between the control electrode 26 and the toner carrier 22 is not particularly limited. Each ring-shaped electrode 27 is provided with an opening having an opening diameter of 200 μm.

The size of the gates 29, 29, and the materials and thicknesses of the substrate 26a and the ring-shaped electrode 27 are not particularly limited. Each of the ring electrodes 27 is
It is electrically connected to the control power supply unit 31 via a power supply line 41 and a high-voltage driver (not shown). Note that the number of ring electrodes 27, 27 is not particularly limited. The surfaces of the ring-shaped electrodes 27, 27, the power supply lines 41, 41 and the surface of the shield electrode 39 have a thickness of 30 mm.
It is covered with an insulating layer 26c (not shown in FIG. 2) of μm, which will be described later, whereby the insulating properties between the ring-shaped electrodes 27, 27, the insulating properties between the power supply lines 41, 41, and the connection between each other. Ring-shaped electrodes 27, 27 and feeder 4
1 and 41 and insulation with the toner carrier 22 and the counter electrode 25 are ensured.

A pulse corresponding to an image signal, that is, a voltage is applied to a ring-shaped electrode 27 of the control electrode 26 by a control power supply unit (control means) 31. That is, when the control power supply unit 31 allows the toner 21 carried by the toner carrier 22 to pass through the ring-shaped electrodes 27 and 27 in the direction of the counter electrode 25 (hereinafter referred to as an ON potential), the control power supply unit 31, for example, is 350
When V is applied and not passed (hereinafter, OFF potential), for example, 0 V is applied. As described above, when the potential applied to the control electrode 26 is controlled in accordance with the image signal and the paper 5 is disposed on the surface of the counter electrode 25 facing the toner carrier 22, the surface of the paper 5 is responsive to the image signal. A toner image is formed. The control power supply 31 is controlled by a control electrode control signal sent from an image forming control unit (not shown).

The above-described image forming apparatus can be used not only as a printer for output from a computer or a word processor but also for a print portion of a digital copy. The forming operation is performed using FIG. First,
For example, when a document to be copied is placed on the image reading unit and a copy start button (not shown) is operated, the main control unit receiving this input starts an image forming operation (step S1). That is, a document image is read by the image reading unit (Step S2), the image data is processed by the image processing unit (Step S3), and stored in the image memory (Step S4).

The image data stored in the image memory is transferred to the image forming control unit (step 5), and the image forming control unit starts converting the input image data into a control electrode control signal to be given to the control electrode 26. (Step S6). When the image forming control unit obtains a predetermined amount of the control electrode control signal, a driving device (not shown) operates, and the pickup roller 6 shown in FIG. The paper 5 is sent out toward the image forming unit 1 (step S12), and the paper feed sensor detects that the paper is in a normal paper feed state (step S13). The sheet 5 sent out by the pickup roller 6 is extruded at a predetermined speed by the registration roller 125, reaches the suction port 94, and is conveyed to the area where the counter electrode 25 and the control electrode 26 face each other while being sucked. In this state, the paper 5 is
It moves at a predetermined speed while sliding on 26. The predetermined amount of the control electrode control signal varies depending on the configuration of the image forming apparatus.

Thereafter, the image forming control unit supplies the control electrode control signal to the control power supply 31 (step S15). The control power supply unit 31 controls a high voltage applied to each ring-shaped electrode 27 of the control electrode 26 based on the control electrode control signal. That is, a potential of 350 V or 0 V is appropriately applied to the predetermined ring-shaped electrode 27 from the control power supply unit 31, and the electric field near the control electrode 26 is controlled.
That is, in the gate 29 of the control electrode 26, the prevention of the flying of the toner 21 from the toner carrier 22 to the counter electrode 25 and the release thereof are appropriately performed according to the image data (step S15). Thereby, the paper guides 124 and 12
6, a toner image corresponding to the image signal is formed on the paper 5 moving toward the paper output side. After the sheet 5 on which the toner image is formed is conveyed to the fixing unit 11, the toner image is fixed on the sheet 5 by the fixing unit 11. The paper 5 on which the toner image has been fixed is discharged onto a paper tray by a paper discharge roller, and a normal discharge is detected by a paper discharge sensor. Based on this detection operation, the main control unit determines that the printing operation has ended normally (step S16). By the above image forming operation, a good image is formed on the sheet 5.

In the present image forming apparatus, since an image is formed directly on the sheet 5, a visualizing member such as a photosensitive member or a dielectric drum used in a conventional image forming apparatus is not required. Therefore, the transfer operation of transferring the image from the visualized object to the sheet 5 is omitted, so that the image does not deteriorate. For this reason, the reliability of the device is improved. In addition, since the configuration of the apparatus is simplified and the number of parts is reduced, the size and the cost can be reduced.

In the case where the image forming apparatus according to the above embodiment is used as a print portion of an output terminal of a computer or a print portion of a digital copy, there are differences in the image signals to be processed and their exchanges. The image forming operation method itself has no difference. The potential applied to the ring-shaped electrodes 27 of the control electrode 26 to prevent the passage of the toner 21 and the potential applied to the passage of the toner 21 through the ring-shaped electrode 27 do not depart from the scope of the present invention. There is no particular limitation.

The cleaning operation of the control electrode 26 in the above embodiment will be described. When cleaning the control electrode 26, an oscillating potential as shown in FIG.
5 is given. In FIG. 4, for example, a rectangular wave having a frequency of 50 Hz, an amplitude of 2 kV, and a duty of 50% is applied as a cleaning potential between sheets during continuous printing to form a cleaning electric field. FIG. 5 schematically shows the behavior of the toner 21 attached to the control electrode 26 in such a state. The toner 21 attached to the control electrode 26 is first attached to the surface of the control electrode 26 as shown in FIG. In FIG. 5, the toner 21 represented by ● represents the positively charged toner 21, and the toner 21 represented by ○ represents the oppositely charged toner 21. In this state, when a cleaning potential as shown in FIG. 4 is applied to form a cleaning electric field, vibration is applied to the toner 21 attached to the control electrode 26, and the control electrode 2
Adhesive force such as van der Waals force on the control electrode 26 is weakened, and the control electrode 26 is separated from the toner 21 having a weak adhesive force on the control electrode 26 as shown in FIG.
Start flying for 5. FIG. 5B shows a case where the same electric field as in printing is applied.

The toner 21 flying in FIG.
5C, when the electric field arrives at the counter electrode 25 and then an electric field in the opposite direction to that during printing is applied, the toner returns from the counter electrode 25 to the control electrode 26 as shown in FIG. 21
Then, the oppositely charged toner 21 newly flying by the electric field is generated. Here, among the toner 21 that has reached the counter electrode 25 as shown in FIG. 5E, the toner 21 which starts flying against the control electrode 26 as shown in FIG. The toner 21 remaining on the surface of the toner 25 exists.

When a potential as shown in FIG. 4 is applied, the electric fields applied in FIGS. 5B and 5D have opposite directions but the same electric field strength, and therefore, the electric fields given in FIG. ) And FIG.
It seems that the amount of toner 21 flying in (D) is equal. That is, the amount of the toner 21 flying from the control electrode 26 to the counter electrode 25 and the amount of the toner 21 flying from the counter electrode 25 to the control electrode 26 should be equal. However, actually, as shown in FIG. 5D, the amount of the toner 21 flying toward the control electrode 26 is reduced.
Less.

This is for the following reason. Control electrode 26
When the adhesion force of the toner 21 to the counter electrode 25 is compared with the adhesion force of the toner 21 to the counter electrode 25, if the adhesion force is reduced by applying vibration to the toner 21 as in the present embodiment, the mirror image force is extremely low Occupies a large weight. Therefore, as shown in FIG. 6, comparing the image force F1 on the surface of the control electrode 26 and the image force F2 on the surface of the counter electrode 25, the image force F1 acting on the shield electrode 39 via the protective layer 26c, which is a dielectric, and the metal force F1 Considering that the image force is inversely proportional to the square of twice the distance between the charge and the metal, the mirror image force F2 when the toner 21 exists on the surface is F1 << F2, that is, the counter electrode of the control electrode. It can be easily understood that the relationship between the adhesive force Fc of the developer adhered to the side surface and the adhesive force Fb of the developer adhered to the counter electrode is Fc << Fb. Therefore, even when an electric field in the opposite direction to that of FIG. 5B is applied in the state as shown in FIG. 5C, the electric field which satisfies Fc <FE <Fb by adjusting the electrode force FE received from the applied electric field. In this case, the same amount as the amount of flight from the control electrode 26 to the counter electrode 25 does not return from the counter electrode 25 to the control electrode 26,
Although a part returns to the control electrode 26 as shown in FIG. 5D, a part cannot fly due to the above-mentioned mirror image force and stays at the counter electrode 25.

Further, the toner 21 that has returned from the counter electrode 25 to the control electrode 26 is the toner 2 remaining on the control electrode 26.
When the same electric field as that shown in FIG. 5B is applied again as shown in FIG. 5E due to a phenomenon such as collision with the toner 1, the toner that did not fly in FIG. 21 starts a new flight. Such a behavior is caused by the positively charged toner 21.
The same applies to the oppositely charged toner 21 as well.
Such an operation is repeated, and the toner 21 finally attached to the control electrode 26 as shown in FIG.
5 and the control electrode 26 is cleaned.

(Embodiment 2) As a result of performing the operation shown in Embodiment 1 above, when the amount of toner 21 that needs to be cleaned increases, toner 21 adheres to toner 21 adhered to counter electrode 25. Condition occurs. (F) of FIG.
As shown in (2), since the image force acting on the toner 21a is smaller than that of the toner 21 attached to the first layer of the counter electrode 25, the toner 21a is easily moved and continues to move along the vibrating cleaning electric field. The final electric field determines the electrode that is ultimately deposited. Therefore, it is necessary to define the direction of the last electric field of the cleaning electric field. For example, when the polarity of the toner 21 attached to the control electrode 26 is positive, it is better that the last polarity applied to the counter electrode 25 is terminated with a negative polarity as shown in FIG. It was cleaning. In the second embodiment, the applied electrode has a frequency of 150 Hz, an amplitude of 2 kV, and a duty of 50%. However, the voltage may be appropriately adjusted according to use conditions (distance between the counter electrode 25 and the control electrode 26, charge amount of the toner 21, and the like).

(Embodiment 3) As a result of performing the operation shown in Embodiment 1, when the amount of toner that needs to be cleaned increases, the toner 21 is laminated on the counter electrode 25 as shown in FIG. Although the toner 21 close to the counter electrode 25 is restrained by the mirror image force, the restraining force of the toner 21a on the surface of the stacked toner 21 is weak, and the toner 21 receives a repulsive force from the toner 21 between the toner 21 and the counter electrode 25. At the moment when the cleaning power is exhausted, the airplane flies backward toward the control electrode 26. As a means for solving this, as shown in FIG. 8, cleaning the toner 21 from the counter electrode 25 in a state in which a cleaning electric field of a negative polarity is applied, provided better cleaning without reverse flight.

(Embodiment 4) In addition to the cleaning system as in each of the above embodiments, as shown in FIG.
By adding a structure (not shown) to change the inclination of the electrode and a collecting hole, a contact portion such as a bristle brush or a blade that causes wear of the electrode surface is not used, no magnetic force is required, and non-magnetic force is not required. This is a system in which the magnetic developer is electrostatically carried to a portion where no control electrode is provided, and the toner 21 capable of returning the non-magnetic developer to the developer carrier is recycled. This is because when charged particles such as toner 21 are present in regions where the electric field strength differs between the left and right as shown in FIG. 10 and an AC electric field is applied between the electrodes, the charged particles are in a direction in which the electric field is weak (in FIG. (Left side) while moving reciprocatingly between the electrodes (according to the arrow in FIG. 10).

This operation will be described. Toner 21 adheres to the surface of control electrode 26 after printing is completed. In this state, the counter electrode 25 is set so as not to be parallel to the control electrode 26.
By applying a voltage of 0 Hz amplitude 2 kV and a duty 50%, the toner 21 is carried to the toner collecting hole 29 a while reciprocating between the control electrode 26 and the counter electrode 25. The moved toner drops off to the toner carrier 22 through a toner collecting hole 29a provided outside the printing area. In this case, the dielectric layer 25c is provided on the surface of the counter electrode 25 to reduce the mirror image force on the counter electrode 25, so that the adhesion to the counter electrode 25 during transportation can be suppressed, so that more effective transport is possible.

(Embodiment 5) The reciprocating area of the toner 21 spreads out of the printing area due to the reciprocating movement of the toner 21 during cleaning.
Scattering of the toner 21 occurs. This is because, when the toner reciprocates during the formation of the cleaning electric field, the toner 21 bounces when it collides with the counter electrode 25 and the control electrode 26 as shown in FIG. 11D, and the Coulomb force between the toners 21 during movement. Fq
Because a force in the divergent direction such as repulsion due to the toner is applied, the toner 2
The cleaning process proceeds as shown in FIGS. 11A, 11B, and 11C, while the adhesion region gradually expands each time the toner 21 moves, as compared with the original region where 1 has adhered.

For example, when the cleaning time is 1 second, about 5 m
m, about 10 mm for 2 seconds, about 15 mm for 3 seconds
And the toner 21 was scattered in the printing area. In order to solve this problem, in addition to the cleaning method of the above-described embodiment, it is necessary to form an electric field such that a force acts on the toner 21 in the direction of convergence into the print area as shown in FIG. For example, as shown in FIG. 12, the counter electrode 25 is larger than the print area, and the distance between the counter electrode 25 and the control electrode 26 is smaller in the print area than in the print area. Since the electric field intensity in the printing area is weakened and the toner 21 receives a force in the center of the printing area, good cleaning without scattering of the toner 21 outside the printing area is obtained.

(Embodiment 6) Since the toner 21 reciprocates between the control electrode 26 and the counter electrode 25 by the cleaning electric field,
Friction charging is caused between the dielectric layer 26c on the surface of the control electrode 26 and the toner 21. Since this charging adversely affects the printing electric field, it is necessary to release the charged charges. In this case, as shown in FIG. 14, the high resistance film 2 is formed on the surface of the dielectric protection layer 26c.
The provision of the high resistance film 26d allows the charge to escape, but in order for the toner 21 to reciprocate with the high resistance film 26d provided, the charge flows around the toner 21 on the high resistance film 26d and the mirror image is formed. It is necessary to make a reverse electric field before the force increases. The adhesive force of the toner 21 on the high-resistance film 26d is small as shown in FIG. 13A at the moment of adhesion, as shown in FIG. 13A, but is small with time as shown in FIG. 13B. Goes up. The time when the adhesion becomes strong is determined by the counter electrode 25.
And the resistance C of the high-resistance film 26d and the capacitance C of the high-resistance film 26d. For example, if the frequency is 150 Hz, the capacitance between the counter electrode 25 and the high-resistance film 26d is about 25 pF, so if the resistance value of the high-resistance film 26d is 1 × 10 ⁻⁸ Ωcm or more, the cleaning state is good. there were.

(Embodiment 7) By forming a potential distribution 100 as shown in FIG. 15 at the time of forming the cleaning electric field, the toner 21 adhering to the control electrode 26 once adheres to the counter electrode 25 and then the control electrode 26 Is returned to the toner carrier 22 while converging toward the center of the ring-shaped electrode 27 when returning. For example, when the toner 21 adhered to the control electrode 26 has a positive polarity, the cleaning voltage is reduced by -5 from the printing voltage to the toner carrier 22 when a cleaning electric field is formed.
By switching to 00V, a potential as shown in FIG. 15 is obtained. Further, at this time, if clogging occurs during printing, there is a problem that the toner 21 that has reciprocated cannot return to the toner carrier 22. This problem can be solved by increasing the kinetic energy when the returned toner 21 collides with the clogging and punching out the clogging.

For example, as shown in FIG. 16, when the cleaning electric field is formed, the counter electrode 25 is rotated (indicated by an arrow) to switch to the cleaning electrode and simultaneously to the cleaning power source to control the counter electrode 25 and the control electrode 26. The electrode 26 is made larger than at the time of printing, and the counter electrode 25-the control electrode 26
This is made possible by making the potential difference between them larger than during printing. Since the energy of the toner 21 is determined by the potential difference, the clogging which cannot be broken by the energy at the time of printing can return the energy of the toner 21 returned by increasing the potential difference at the time of cleaning to be larger than the energy at the time of printing. Thus, it is possible to punch out clogging. At this time, the larger the potential difference, the better, and preferably, the counter electrode 25 -the control electrode 2 at the time of printing.
If the potential difference is increased in the state of the distance between 6, there is a possibility that a leak may occur. Therefore, it is better to increase the potential difference up to the point where the leak occurs after making the counter electrode 25-the control electrode 26 larger than at the time of printing, so that the cleaning state is better. Met.

(Embodiment 8) The removal of the toner 21 adhered to the control electrode 26 is performed by dividing the counter electrode 10 as shown in FIG.
1 to the divided opposing electrodes 101 alternately, for example,
By applying + 500V and -500V as the power supply 1 and the power supply 2, an extremely uneven electric field is formed near the electrodes. For example, in the configuration shown in FIG. 18, after printing, the counter electrode 25 rotates and the divided counter electrode 101 is used for cleaning.
Face the control electrode 26 (position shown). When the voltage is applied to the cleaning power supply at the same time as the confrontation, the toner 21 is attracted to the portion where the electric field is concentrated irrespective of the charging polarity and the charging amount as shown in FIG.
Can be collected by the divided opposing electrode 101. In this way,
By removing the toner adhering to the control electrode by using the divided opposing electrodes, it is not necessary to use an expensive and dangerous power supply having a high-voltage and high-speed response required for forming an oscillating electric field.

(Embodiment 9) The removal of the toner 21 adhered to the control electrode 26 is performed by using a divided counter electrode roll 102 as shown in FIG. For example, as shown in FIG.
3, the power supply 2 for the electrode 104 and the printing voltage +
Printing is performed while 1000 V is applied and rotating. After the printing is completed, the electrode 103 is switched to -1000 V during cleaning, so that the toner attached to the control electrode can be removed without using a high-voltage, high-speed, high-speed and expensive power supply which is necessary for forming an oscillating electric field. An oscillating electric field can be generated between the control electrode 26 and the divided counter electrode roll 102, and the toner collecting effect due to the concentration of the electric field can be expected. The toner 21 adhering to the control electrode 26 due to the oscillating electric field is removed by a collecting device (not shown).

(Embodiment 10) In the above embodiment, since the control electrode 26 is cleaned by moving the toner adhered to the control electrode 26 to the counter electrode 25, a cleaning means for the counter electrode 25 is separately provided. desirable. As shown in FIG. 22, in the present embodiment, as described above,
Cleaning brush 25b and cleaning brush 25
b driving means 25d is arranged. The driving unit 25d and the cleaning brush 25b have, for example, a form as shown in FIG. 22, and the counter electrode 25 is rotationally driven by the driving unit 25d. The drive means 25d can be moved in the direction of the arrow in the figure by rotation of a motor 25f which rotationally drives a shaft 25e provided with a thread groove. Further, the counter electrode 25 is a driving means 25g for performing a predetermined rotational drive.
The counter electrode 25 is rotationally driven so that good printing and good cleaning of the counter electrode 25 can be performed at a predetermined timing.

In such a configuration, for example, the counter electrode 25 is rotated before or after the control electrode 26 is cleaned between papers or the like. The plane of the counter electrode 25 facing the cleaning brush 25b is a driving unit 25d.
Cleaning by the cleaning brush 25b that moves
Before the sheet 5 is conveyed, the control electrode 2
6 is driven and controlled. In the above embodiment, the counter electrode 25 has a plate-like shape, but is not limited to this. For example, the counter electrode 25 may have any shape such as a polygonal cross-sectional shape that can provide good printing and good cleaning. . As described above, the developer moved from the control electrode 26 to the counter electrode 25 is further cleaned and removed by a mechanical action, so that the toner 21 attached to the counter electrode 25 is transferred to the surface of the sheet 5 transported to the surface. It does not adhere to the back surface and does not cause back stains on the paper 5.

In the above embodiment, the potential applied to the counter electrode 25 is an oscillating potential having no DC component as shown in FIG. 4, and the electric field formed between the control electrode 26 and the counter electrode 25 also has a DC component. An oscillating electric field that does not have Further, in the above embodiment, the electric field intensity of the electric field formed by the vibration component is formed to be equal in the direction toward the counter electrode 25 and the direction toward the control electrode 26, for example.
As a result, the cleaning operation is performed on the positively charged toner 21 and the oppositely charged toner 21 completely equally as described above.
Good cleaning of the control electrode 26 is obtained irrespective of the charging polarity of the toner 21. However, when the oscillating electric field formed in the above configuration has a DC component, the cleaning of the toner 21 of the polarity corresponding to the DC component is effective, while sufficient toner is removed for the toner 21 of the opposite polarity. 21 may not be obtained. However, if a good cleaning can be obtained, the control is not limited to the control having no DC component, and there is no problem in the control having the DC component.

On the other hand, if there is a biased characteristic such as a large or a small amount of charge of the toner 21 of one polarity, a configuration in which a DC component is appropriately adjusted and provided by utilizing these characteristics. And a more effective cleaning operation can be obtained. In the case of ordinary toner, there is no significant difference in characteristic values between the positively charged toner and the oppositely charged toner. Therefore, the best cleaning can be obtained by the oscillating electric field having no DC component as described above.

In the above embodiment, the shield electrode 39 disposed on the control electrode 26 is grounded. However, the present invention is not limited to this. For example, a potential of about 50 V may be applied. In this case, the oscillating electric field formed even if the above-described cleaning potential is applied has only a very small DC component.
Since it has only a DC component of 0 V, the effect of the cleaning electric field by the cleaning potential is obtained almost equal to the case where the shield electrode 39 is grounded as described above, and good cleaning is obtained.

Furthermore, in the above embodiment, a rectangular wave is supplied as the cleaning potential, but the present invention is not limited to this.
Potential waveforms including various vibration components such as triangular waves and limited waves can be used. However, the most effective is a potential waveform such that a very large change is obtained at the moment when the direction of the electric field formed like a rectangular wave or an impulse train composed of impulses of opposite polarities as in the above embodiment is changed. . The characteristics of these waveforms, that is, in a transitional period in which the direction of the electric field changes instantaneously, the same effect as when vibration is applied to the attached toner 21 in a very wide frequency range is obtained. There is an advantage that the cleaning effect is enhanced.

In the above embodiment, the shield electrode 39 is arranged on the counter electrode 25 side as the control electrode 26 to be used. However, the configuration of the control electrode is not limited to this. A method of arranging the shield electrode 39 and a structure of arranging the shield electrode 39 on the toner carrier 22 side and the counter electrode 25 side are also possible, and a favorable cleaning operation can be obtained as described above.

In the above embodiment, the toner 2
One flight control has been described in the case of the control electrode 26 by a single drive in which each gate 29 is controlled by one electrode. However, the present invention is not limited to the case where the control electrode 26 using the matrix control as shown in FIG. The same can be applied, and good image formation can be achieved. In FIG. 23, band electrodes 27a and 27b are arranged instead of the ring electrodes 27. A band electrode 27b is disposed on the toner carrier 22 side of the control electrode 26, and a band electrode 27a is disposed on the counter electrode 25 side. In the control electrode 26 of FIG. 23, F is a switching means for switching the potential of each gate 29.
The number of ETs can be significantly reduced. For example, in comparison with the control electrode 26 shown in FIG. 2, the number of FETs required for the control electrode 26 shown in FIG. 23 is reduced to about 1/4. From the viewpoint of reducing the number of FETs used in this manner, FIG.
The control electrode 26 as shown in FIG. 3 is very effective.

Further, the cleaning operation as described above is performed between continuous printing sheets, but is not limited to this. For example, before starting printing, after finishing printing, after turning on the power, or after clearing the paper jam. It is desirable to perform at each timing. Further, the amplitude, frequency, or duty of the potential used for the above-described cleaning is not limited to the above, and may vary depending on the characteristics of the toner 21 used, the characteristics of the dielectric layer disposed on the surface of the counter electrode 25, and the like. Adjustment to obtain good cleaning is preferable and cannot be uniquely determined.

In this embodiment, the case where the developer is a toner has been described as an example, but the developer may be an ink or the like. Further, the configuration of the toner supply unit 2 is
It is also possible to adopt a configuration to which an ion flow method is applied. That is, the image forming unit may be configured to include an ion source such as a corona charger. In this case, the same operation and effect as described above can be obtained.
In the present embodiment, the case where the developer is toner is described as an example, but the developer may be ink or the like. The image forming apparatus according to the present invention can be suitably applied to, for example, a printing unit of a digital copying machine and a facsimile machine, a digital printer, a plotter, and the like.

[0063]

According to the first aspect of the present invention, the direction of the last electric field of the cleaning electric field is defined, so that the mirror force generated when the amount of the developer that needs to be cleaned is increased is reduced. The cleaning effect is further improved by deciding the electrode to which the developer is easily attached finally.

According to the second aspect of the present invention, even when the amount of the developer which needs cleaning is increased, the developer which flies backward toward the control electrode at the moment when the cleaning electric field disappears is not generated on the counter electrode. Focusing enables more effective cleaning.

According to the third aspect of the present invention, the surface of the electrode such as a bristle brush or a blade is worn by applying a cleaning electric field between the electrodes in a configuration having different electric field strengths by offsetting the electrodes from the parallel arrangement. The non-magnetic developer can be electrostatically conveyed to the portion without the control electrode without using a simple contact member.

According to the fourth aspect of the present invention, the structure in which the distance between the counter electrode and the control electrode is made smaller in the direction outside the printing region than in the printing region is employed, so that the electric field intensity in the printing region is smaller than the electric field intensity outside the printing region. The electric field strength of the developer becomes weaker, and the developer receives a force in the direction of the center of the print area, so that the developer does not scatter outside the print area due to the reciprocating movement of the developer during the application time of the cleaning electric field. Cleaning is now possible.

According to the fifth aspect of the present invention, since the developer reciprocates between the control electrode and the counter electrode by the cleaning electric field,
Charges that adversely affect the image occur due to friction between the dielectric layer on the control electrode surface and the developer, and if a conductive film is provided to eliminate the charge, the charge can be removed, but the developer is affected. The cleaning ability is reduced due to the increased mirror image power. Since the mirror image force increases with the adhesion time, it is possible to achieve both static elimination and cleaning by applying a reverse electric field before the adhesion force increases.

According to the sixth aspect of the present invention, the electric field between the developer carrier and the control electrode as a cleaning electric field directs the developer adhering to the surface on the counter electrode side to the developer carrier and the control electrode. When a cleaning electric field is formed in which the equipotential surface of the hole is convex toward the counter electrode, the developer adhered on the control electrode once adheres to the counter electrode and then returns to the control electrode in a ring shape. Since it is returned to the developer carrier while converging toward the center of the electrode, it does not adhere to the electrode, or returns to the developer carrier without inducing clogging under bad conditions, and Effective use is achieved.

According to the seventh aspect of the present invention, when the cleaning electric field is formed, the distance between the counter electrode and the control electrode is made larger than when printing, and the potential difference between the counter electrode and the control electrode is made larger than when printing, so that leakage is reduced. Without causing
The kinetic energy of the developer is increased, clogging is punched out, and a good cleaning state is obtained.

According to the eighth aspect of the present invention, the toner adhered to the control electrode is removed by using the divided electrodes forming an uneven electric field, so that the developer is independent of the charge polarity and the charge amount of the developer. Can be collected on the split electrode.

The effect of the ninth aspect of the invention: In addition to the effect of the eighth aspect of the present invention, an extremely large uneven electric field is formed by alternately applying + and-voltages to the divided electrodes. The developer can be collected on the divided electrodes regardless of the charge polarity and charge amount of the developer without using an expensive and dangerous power supply with a high pressure and high speed response.

According to the tenth aspect of the present invention, by using the divided electrode roll, an oscillating electric field can be generated between the control electrode and the divided electrode roll without using a dangerous power source for high-speed and high-speed response. The developer can be collected irrespective of the charge polarity and charge amount of the developer.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a configuration of an embodiment of a control electrode of the image forming apparatus according to the present invention.

FIG. 3 is a diagram showing a flow of a printing operation in the image forming apparatus according to the present invention.

FIG. 4 is an explanatory diagram illustrating an example of a cleaning potential applied to a counter electrode in the image forming apparatus according to the present invention.

FIG. 5 is an explanatory diagram for explaining the behavior of the developer due to the cleaning electric field in the image forming apparatus according to the present invention.

FIG. 6 is an explanatory diagram for explaining a mirror image force on both surfaces of a control electrode and a counter electrode.

FIG. 7 is an explanatory diagram for explaining an adhesive force of a developer between a control electrode and a counter electrode.

FIG. 8 is an explanatory diagram illustrating an example of a cleaning potential applied to a counter electrode in the image forming apparatus according to the present invention.

FIG. 9 is an explanatory diagram illustrating an operation of returning the toner to the toner carrier in the embodiment of the image forming apparatus according to the present invention.

FIG. 10 is an explanatory diagram illustrating the behavior of a toner in an uneven electric field between a control electrode and a counter electrode.

FIG. 11 is an explanatory diagram illustrating a diffusion factor of toner during cleaning in the image forming apparatus according to the present invention.

FIG. 12 is an explanatory diagram illustrating a structure for preventing toner diffusion in an embodiment of the image forming apparatus according to the present invention.

FIG. 13 is an explanatory diagram illustrating a mirror image force when a high-resistance film is provided on a control electrode in the image forming apparatus according to the present invention.

FIG. 14 is a diagram illustrating a configuration of an embodiment in which a high resistance film is provided on a control electrode in the image forming apparatus according to the present invention.

FIG. 15 is an explanatory diagram illustrating an electric field and a flying trajectory of toner in the image forming apparatus according to the present invention.

FIG. 16 is a diagram showing a configuration of one embodiment of a counter electrode in the image forming apparatus according to the present invention.

FIG. 17 is a diagram illustrating an example of a divided counter electrode in the image forming apparatus according to the present invention.

FIG. 18 is an explanatory diagram for explaining an operation in the image forming apparatus according to the present invention having the divided opposing electrodes.

19 is an explanatory diagram illustrating the principle of toner recovery of the divided opposing electrodes in FIG.

FIG. 20 is a diagram illustrating an example of a divided counter electrode roll in the image forming apparatus according to the present invention.

FIG. 21 is an explanatory diagram illustrating an operation in the image forming apparatus according to the present invention having the divided opposing electrode rolls.

FIG. 22 is an explanatory diagram for explaining a counter electrode cleaning unit and its method in the image forming apparatus according to the present invention.

FIG. 23 is a diagram showing a configuration of another embodiment of the control electrode in the image forming apparatus according to the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Image forming part, 2 ... Toner supply part, 3 ... Printing part, 4 ...
Paper cassette, 5: paper, 6: pickup roller, 7
... Sheet feeding guide, 10 ... Sheet feeding device, 11 ... Fixing unit, 12 ...
Heating roller 13 Heater 14 Pressure roller 15
Temperature sensor, 20: toner storage tank, 21, 21a: toner, 22: toner carrier, 23: doctor blade, 2
5 ... counter electrode, 25b ... cleaning brush, 25c ... dielectric layer,
25d drive means, 25e shaft, 25f motor, 25g drive means, 26 control electrode, 26a insulating substrate, 26c insulator (dielectric) layer, 26d high resistance film, 27 ring shape Electrodes, 27a, 27b strip electrodes, 29 gate, 29a toner collecting hole, 30 high voltage power supply, 31 control power supply unit, 39 shield electrode, 41
... power supply line, 80 ... temperature control circuit, 92 ... suction device, 93
... Fan, 94 ... Inlet, 96 ... Chamber, 100 ...
Potential distribution, 101: divided counter electrode, 102: divided counter electrode roll, 103, 104: electrodes of divided counter electrode roll, 124, 126, 128: paper guide, 125:
Registration roller.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Daisaku Imaizumi 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka

Claims (10)

[Claims] A supply means for supplying a developer from the carrier; a counter electrode disposed opposite to the support; a counter electrode and the support; High-voltage power supply means for supplying a voltage that generates a high potential difference between
An insulating substrate provided between the carrier and the counter electrode and provided with a gate forming a passage portion of a developer, a control electrode provided around the gate on the insulating substrate, Control circuit means for controlling the potential state of the electrode, wherein the control circuit means controls the passage of the developer from the supply means through the gate by applying a predetermined potential to the control electrode; An image forming apparatus in which a developer that passes through the developer and flies toward the counter electrode forms an image on the surface of a recording medium, and the adhesive force Fc of the developer that has adhered to the counter electrode side surface of the control electrode; Providing a dielectric layer on the counter electrode side of the control electrode so that the relationship between the developer and the adhesive force Fb attached to the counter electrode is Fc <Fb;
A cleaning electric field in which the direction of an electric field changes due to a vibration component between the counter electrode and the control electrode, and a relationship between the electric force FE applied to the developer adhered to the control electrode by the cleaning electric field and the Fb and the Fc Is applied so as to satisfy Fc <FE <Fb, the developer adhered to the control electrode is removed, and the DC component of the cleaning electric field is very small with respect to the vibration component, or the DC component is reduced. In the image forming apparatus having no electric field, at the end of the operation of applying the cleaning electric field,
The image forming apparatus is characterized in that the last electric field direction ends in a direction in which the developer adhered to the surface of the control electrode facing the counter electrode is directed toward the counter electrode. 2. The image forming apparatus according to claim 1, wherein the cleaning electric field is applied to a state in which the developer on the control electrode attached to the surface of the counter electrode applies an electric field in a direction toward the counter electrode. An image forming apparatus, wherein the developer on the counter electrode is removed by maintaining the developer. 3. The image forming apparatus according to claim 1, wherein the relationship between the effective working surfaces of the control electrode and the counter electrode is offset from a parallel arrangement when the cleaning electric field is formed. Image forming device. 4. The image forming apparatus according to claim 3, wherein said counter electrode has an electrode area having an area larger than a print area thereof, and prints a distance between said counter electrode and said control electrode. An image forming apparatus, wherein the area outside the printing area is made smaller than that inside the area. 5. The image forming apparatus according to claim 1, wherein a high resistance film is provided on a surface of said dielectric layer outside a printing area, and a resistance of said high resistance film and said high resistance film are provided. An image forming apparatus, wherein a time constant determined by the capacitance between the counter electrode and the counter electrode is larger than the oscillation period of the cleaning electric field. 6. An image forming apparatus according to claim 1, wherein an electric field between said control electrode and a carrier carrying said developer adheres to said counter electrode side surface as said cleaning electric field. An image forming apparatus, wherein an equipotential surface of the gate portion is made to project toward the counter electrode in a direction toward the developer carrier. 7. The image forming apparatus according to claim 1, wherein a distance between the counter electrode and the control electrode is larger when forming the cleaning electric field than when printing, and the distance between the counter electrode and the control electrode is larger than when printing. An image forming apparatus characterized in that a potential difference between control electrodes is made larger than at the time of printing. 8. A supply means having a carrier for carrying a developer and supplying the developer from the carrier, a counter electrode disposed opposite to the carrier, and a counter electrode and the carrier. High-voltage power supply means for supplying a voltage that generates a high potential difference between
An insulating substrate provided between the carrier and the counter electrode and provided with a gate forming a passage portion of a developer, a control electrode provided around the gate on the insulating substrate, Control circuit means for controlling the potential state of the electrode, wherein the control circuit means controls the passage of the developer from the supply means through the gate by applying a predetermined potential to the control electrode; An image forming apparatus in which a developer that passes through the developer and flies toward the counter electrode forms an image on the surface of a recording medium, wherein the counter electrode is a plurality of split electrodes, and An image forming apparatus, wherein an uneven electric field is formed between electrodes to remove a developer adhered to the control electrode. 9. The image forming apparatus according to claim 8, wherein different voltages are alternately applied to the divided electrodes. 10. The image forming apparatus according to claim 8, wherein the counter electrode is a split electrode roll, and a cleaning electric field is formed on the split electrode roll while rotating the split electrode roll. apparatus.