JP2001518412A - Image forming method and apparatus, and cleaning device - Google Patents

Abstract

(57) [Problem] By combining airflow and electrostatic force by an electric field, a small airflow generating means and a non-magnetic toner adhering to a toner control member with a safe applied voltage that does not generate discharge can be obtained. The present invention also provides an image forming method and apparatus capable of obtaining good cleaning performance. When a non-image is formed, a cleaning electric field is generated in the space that generates an air current in a space adjacent to the toner control member and moves toner in a direction away from the toner control member. For example, a slit 2a is formed in the outer peripheral portion of the sleeve-shaped rotatable counter electrode member 2, and an air flow source 10 such as a fan is connected to the slit 2a. A cleaning electrode 11 formed in a convex shape is formed around the slit 2 a of the counter electrode member 2, and a voltage for forming a cleaning electric field is applied to the cleaning electrode 11 from a cleaning power supply 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

【Technical field】

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning technique for removing powder attached to a surface to be cleaned, and more particularly, records a chargeable powder as an image forming substance via a powder control member having a powder passage hole. Image formation in which an image is formed on the recording medium by causing the powder to fly toward the medium and selectively passing the powder to fly toward the recording medium through the powder passage holes based on the image information In the method and apparatus, the present invention relates to a cleaning technique for removing powder attached to the surface of the powder control member.

[0002]

[Background Art]

2. Description of the Related Art Conventionally, as this type of image forming method and apparatus, those employing an image forming method called direct toning or toner projection are known. In this image forming method, for example, a voltage is applied to a control electrode provided around a powder passage hole formed of a slit or a plurality of minute passage holes of a powder control member based on image information, and the charged powder is charged. Is selectively moved (flies) through the powder passage hole, and the toner is directly applied to a recording medium such as paper to form an image. In the image forming apparatus employing the above-described image forming method, when the image forming operation is continued, the powder is formed on the surface of the powder control member, particularly on the surface of the portion where the powder passage hole of the powder control member is formed. There were cases where dust and dirt adhered. If the powder or dust adheres to the surface of the powder control member in this manner, the flying of the powder toward the recording medium cannot be controlled as intended, and the image quality may be degraded.

Therefore, various cleaning methods and apparatuses for cleaning the surface of the powder control member have been conventionally known. For example, as a method of cleaning using a mechanical force, a method in which a brush roller that is rotated and driven is brought into contact with a powder control member (see Japanese Patent Application Laid-Open No. 3-21064), and a method in which the powder control member is vibrated. (See, for example, JP-A-4-216072), heating and thermally expanding a powder control member, and shaking off powder or the like adhering to the member by deformation of the powder control member. Method (see Japanese Patent Application Laid-Open No. 4-141458)
And a cleaning method using an air stream (JP-A-58-94481, JP-A-4-191780, JP-T4-505899, JP-A-5-134)
No. 581) is known.

As a method of cleaning using an electromagnetic force, there is known a method in which an electric field is applied to a charged powder and the powder is cleaned by an electrostatic force (Coulomb force) generated in the powder. (JP-A-58-96570, JP-A-58-104)
769, JP-A-58-104711, JP-A-59-188450, JP-A-63-123060, JP-A-3-168767, JP-A-4-269563, JP-A-4 -329154, JP-A-5-138
No. 919).

Further, a combination of the above cleaning methods is also known. For example, in Japanese Patent Application Laid-Open No. 5-92608, a magnetic toner is used as a powder, and a toner transport belt as a powder carrier and a counter electrode member are sandwiched between control grids as powder control members via a gap. In an image forming apparatus provided with a back electrode plate, at the time of non-image formation, a voltage having a polarity opposite to that of the toner is applied to the control grid to promote the separation of the adhered toner by an electrostatic force, and the control grid is formed by a magnetic brush on the toner transport belt. There is disclosed one that removes magnetic toner attached to the control grid surface by rubbing the surface. Further, for example, Japanese Patent Application Laid-Open No. Hei 7-117257 discloses a method in which an air flow and ions are simultaneously sprayed on a mesh electrode serving as a powder control member to remove toner on the mesh electrode while removing static electricity. . Also, for example, in Japanese Patent Application Laid-Open No. 6-234233, a multicolor image generating apparatus provided with a toner carrier as a powder carrier itself and a rear electrode belt as a counter electrode member so as to sandwich a powder control member via a gap is disclosed. There is disclosed an apparatus in which toner attached to a powder control member is dropped by a bristle pad provided on a rear electrode belt, and the toner is sucked and collected through a through hole formed in the rear electrode belt. Further, for example, in Japanese Patent Application Laid-Open No. 5-286165, an image forming apparatus provided with a developing brush roller as a powder carrier and a counter electrode member so as to sandwich an aperture electrode as a powder control member with a gap interposed therebetween. There is disclosed an apparatus in which toner adhered to an electrode is shaken off by vibrating an electrode, and the shaken-down toner is collected on a developing brush roller by an electric field.

However, it has been found that the conventional cleaning method described above has various problems. For example, in the cleaning method using the brush roller, the brush roller rotates while being in contact with the powder control member, so that the powder control member is damaged, or the brush that has fallen off adheres to the developing unit or the powder control member. An abnormal image may be generated. Further, in the cleaning method in which the powder control member is vibrated or the powder control member itself is deformed by heat to shake off the powder, the powder control member may be damaged, and the vibration and the vibration In the deformation, the powder on the powder control member could not be completely removed, and there was a possibility that some of the powder would remain attached. Further, the above-described cleaning method using a magnetic force has a disadvantage that it can be applied only to powder having magnetism.

As a cleaning method capable of obtaining good cleaning characteristics even for non-magnetic powder without damaging the powder control member, there are a cleaning method using the air flow and a cleaning method using the air flow. A cleaning method using an electrostatic force (Coulomb force) can be considered.

However, in order to completely remove the powder adhering to the powder control member by the above-described cleaning method using an air flow, it is necessary to provide a large fan, a pump, or the like as an air flow generation source. In addition to the rise, there is a problem that the noise generated from the fan or the like increases. In addition, as disclosed in the above-mentioned Japanese Patent Application Laid-Open No. Hei 7-117257, when a cleaning method in which an air stream and ions are simultaneously blown to a mesh electrode as a powder control member is adopted, the toner on the mesh electrode is removed. It is considered that good cleaning performance can be obtained even if the air flow is set weak, because it is removed while removing static electricity.However, a corona generator for ion generation is required, which is one of the original merits of direct toning. Simplicity is lost.

[0010] Furthermore, in a method of cleaning using an electrostatic force (Coulomb force), when the powder adhering to the powder control member is to be completely cleaned, a cleaning electric field for applying the electrostatic force to the powder is formed. However, when the applied voltage is increased, discharge may occur. As disclosed in Japanese Patent Application Laid-Open No. 5-92608, the outer magnetic toner is removed by rubbing with a magnetic brush while encouraging the magnetic toner on a control grid as a powder control member to be separated by electrostatic force. In such a case, there is a possibility that the intensity of the electric field for applying the electrostatic force can be reduced to a level that does not generate electric discharge, but there is a problem that it can be applied only to magnetic toner (powder). . Further, Japanese Patent Application Laid-Open No. 5-28
As disclosed in Japanese Patent No. 6165, even when the toner shaken off by vibrating an aperture electrode as a powder control member is collected by a developing brush roller with an electric field, the intensity of the electric field is generated by discharging. There is a possibility that the toner (powder) cannot be reduced to such a degree that the toner (powder) cannot be shaken off by the vibration.

[0010] Further, a plurality of the image forming units are provided for selectively passing a powder which is to fly toward a recording medium based on image information for forming a multicolor image through a powder passage hole of a powder control member. When cleaning the powder control member in an image forming apparatus provided with a set, a configuration in which a cleaning device is provided in parallel with each powder control member can be considered, but a plurality of cleaning devices corresponding to each powder control member are required. However, there is a problem that the number of parts increases. In order to clean the plurality of powder control members,
It is known that a hair-like pad as a cleaning member is provided on a rear electrode belt as a counter electrode member, and the hair-like pad drops toner adhered to the powder control member (Japanese Patent Laid-Open No. Hei 6-234233). Reference), there is a problem that the powder control member may be damaged by the rubbing of the hairy pad.

[0011]

DISCLOSURE OF THE INVENTION

A first object of the present invention is to control the flight of powder as an image forming substance toward a recording medium by a powder control member having a powder passage hole and a control electrode provided around the powder passage hole. An image forming apparatus that forms an image on the recording medium by combining an air current with an electrostatic force generated by an electric field, thereby providing a small air current generating means and a safe applied voltage that does not generate a discharge, An object of the present invention is to provide an image forming method and apparatus capable of obtaining good cleaning performance even for a non-magnetic powder attached to a control member.

A second object of the present invention is to provide a small airflow generating means and a non-magnetic material attached to a cleaning object with a safe applied voltage that does not generate electric discharge by combining an airflow with an electrostatic force caused by an electric field. An object of the present invention is to provide a cleaning apparatus suitable for the image forming method and apparatus, which can obtain good cleaning performance even with respect to powder.

[0013] A third object of the present invention is to provide a method for controlling the flying of a powder as an image forming substance toward a recording medium by using a powder having a powder passage hole and a control electrode provided around the powder passage hole. An image forming apparatus provided with a plurality of image forming units for forming an image on the recording medium by controlling with a body control member, capable of non-contact cleaning of a powder control member which does not cause damage due to rubbing Even when a simple cleaning device is used, an image forming apparatus that can satisfactorily clean each powder control member with a smaller number of parts compared to a configuration in which a plurality of cleaning devices corresponding to each powder control member are provided. To provide.

Further, a fourth object of the present invention is to provide a method in which a powder as an image forming substance flies from a powder carrier to an opposite electrode member around a powder passage hole and around the powder passage hole. An image forming apparatus comprising a plurality of image forming units for forming an image on a recording medium conveyed by a belt member by controlling with a powder control member having a control electrode. An object of the present invention is to provide an image forming apparatus capable of easily cleaning each powder control member without separately providing a cleaning device dedicated to non-contact cleaning of the powder control member.

[0015] In order to achieve the first object, the present invention is directed to flying a chargeable powder as an image forming substance toward a recording medium via a powder control member having a powder passage hole. In the image forming method for forming an image on a recording medium by selectively passing powder that is to fly toward the recording medium through the powder passage hole based on the image information, A cleaning electric field for generating an air current in a space adjacent to the powder control member and moving the powder in a direction away from the powder control member is sometimes formed in the space. In the image forming method of the present invention, an airflow is generated in a space adjacent to the powder control member, and the powder adhering to the surface of the powder control member is cleaned while being separated from the surface. Simultaneously with the cleaning by the air flow, a cleaning electric field is formed to move the powder by electrostatic force in a direction away from the powder control member, and the powder adhering to the surface of the powder control member is removed by the cleaning electric field. Clean while removing from the surface. As described above, the airflow and the electrostatic force are combined, and the cleaning by the airflow and the cleaning by the electrostatic force are simultaneously performed.

In order to achieve the first object, the present invention is directed to flying a chargeable powder as an image forming substance toward a recording medium via a powder control member having a powder passage hole. In the image forming apparatus for forming an image on the recording medium by selectively passing the powder to fly toward the recording medium through the powder passage hole based on the image information, Airflow generating means for generating an airflow in a space adjacent to the body control member,
A cleaning electric field forming means for forming a cleaning electric field for moving the powder in a direction away from the powder control member in the space; and controlling generation of an air flow by the air current generating means and formation of a cleaning electric field by the cleaning electric field forming means. And control means for performing the control. In the image forming apparatus of the present invention, by controlling the airflow generating means by the control means, during non-image formation that does not affect the image on the recording medium, an airflow is generated in a space adjacent to the powder control member. Cleaning is performed while removing the powder adhering to the surface of the powder control member from the surface. Simultaneously with the cleaning by the airflow, the control means controls the electric field forming means to form a cleaning electric field for moving the powder by electrostatic force in a direction away from the powder control member. The cleaning is performed while removing the powder adhering to the surface of the control member from the surface. As described above, the airflow and the electrostatic force are combined, and the cleaning by the airflow and the cleaning by the electrostatic force are simultaneously performed.

In the image forming apparatus of the present invention, the airflow generating means may include an airflow facing member having an airflow port for sucking or blowing out an airflow to the powder control member; A driving means for driving the airflow opposing member so as to be able to take an opposing position approaching and opposing the member and a separated position separated from the powder control member. . In the image forming apparatus of the present invention, the airflow port for sucking or blowing out the airflow is driven by the driving unit at the time of non-image formation by driving the airflow opposing member at the separated position separated from the powder control member. Is moved to an opposing position approaching and opposing the powder control member. By moving the airflow port to the opposed position, the airflow sucked or blown out from the airflow port approaching the powder control member removes the powder attached to the surface of the powder control member for cleaning. I do.

The image forming apparatus according to the present invention includes a powder carrier that supports a chargeable powder as an image forming substance, a counter electrode member disposed to face the powder carrier, A flying electric field forming means for forming a flying electric field for causing the powder on the body carrier to fly toward the counter electrode member; and a flying electric field forming means between the powder carrier and the counter electrode member. A powder control member having a powder passage hole for controlling the flight of powder to the counter electrode member and a control electrode around the powder passage hole, and a power supply for applying a voltage to the control electrode based on image information An image forming apparatus comprising: a cleaning electric field forming unit configured to form the cleaning electric field between a cleaning electrode provided around an airflow port of the airflow facing member and the control electrode. A voltage is applied to the cleaning electrode. It is characterized by using a power source for leaning. In the image forming apparatus of the present invention, at the time of image formation, the powder having chargeability as an image forming substance is caused to fly from the powder carrier toward the counter electrode member by the flying electric field formed by the flying electric field forming means. The flying of the powder toward the counter electrode member is controlled by a powder control member having a powder passage hole and a control electrode to which a voltage is applied based on image information. An image is formed on the recording medium by selectively adhering the powder to the recording medium transported between the recording medium and the recording medium. When a non-image is formed, a voltage is applied from a cleaning power source to a cleaning electrode provided around the airflow port of the airflow facing member, whereby a cleaning electric field is applied between the cleaning electrode and the control electrode of the powder control member. To form The powder adhering to the surface of the powder control member is separated from the surface by the cleaning electric field, and is moved in a direction approaching or away from the airflow port. As the powder separates from and moves from the surface of the powder control member, the powder adhering to the surface of the powder control member is removed and cleaned by an airflow sucked or blown out from the airflow port.

In the image forming apparatus according to the present invention, the counter electrode member is formed of a rotatable cylindrical member or a belt member having the air flow port, and is also used as the air flow counter member. It is. In the image forming apparatus of the present invention, when forming an image, a portion of the counter electrode member, which is formed by using a rotatable cylindrical member or a belt member with respect to the powder carrier, is formed so as to face the portion where the airflow port is not formed. The flying electric field formed by the electric field forming means causes the charged powder as the image forming substance to fly from the powder carrier toward the counter electrode member. The flying of the powder toward the counter electrode member is controlled by a powder control member having a powder passage hole and a control electrode to which a voltage is applied based on image information. An image is formed on the recording medium by selectively adhering the powder to the recording medium transported between the recording medium and the recording medium. Then, at the time of non-image formation, the counter electrode member is rotated so that the air flow port formed in the counter electrode member also serving as the air flow counter member faces the surface of the powder control member, and The powder adhered to the surface of the powder control member is removed and cleaned by the sucked or blown air current.

In the image forming apparatus according to the present invention, the cleaning electric field is mainly formed by a voltage applied to the cleaning electrode. In the image forming apparatus of the present invention, the cleaning electric field between the cleaning electrode provided around the airflow port of the airflow facing member and the control electrode of the powder control member is mainly controlled by the voltage applied to the cleaning electrode. Since it is formed, the potential of the control electrode can be set to be lower than the withstand voltage of an electric circuit component such as an IC connected to the control electrode.

In the image forming apparatus according to the present invention, the cleaning electric field is an electric field obtained by superposing an alternating electric field on an electrostatic field. In the image forming apparatus of the present invention, a cleaning electric field in which an alternating electric field is superimposed on an electrostatic field is formed in a space adjacent to the powder control member, and a force for reciprocating the powder adhered to the powder control member. Makes the powder easier to separate from the surface of the powder control member than when a cleaning electric field consisting only of an electrostatic field is formed.

In the image forming apparatus of the present invention, the frequency of the alternating electric field is 0.5 kHz or more and 3
kHz or less. In the image forming apparatus of the present invention, by setting the frequency of the alternating electric field of the cleaning electric field to the predetermined range, a force for reciprocating the powder adhered to the powder control member is more reliably applied. .

In the image forming apparatus of the present invention, the direction of the air current and the cleaning electric field are set so that the direction of movement of the powder moving with the air current is substantially the same as the direction of the powder moving with the cleaning electric field. Is set. In the image forming apparatus of the present invention, the direction of movement of the powder moving by the air current is substantially the same as the direction of the powder moving by the cleaning electric field, so that the direction of separation from the powder control member by the cleaning electric field is increased. Is moved by the airflow in substantially the same direction as the direction of the movement.

In the image forming apparatus according to the present invention, the maximum value of the cleaning electric field is set to a value smaller than a discharge starting electric field obtained based on Paschen's discharge curve. In the image forming apparatus of the present invention, the maximum value of the cleaning electric field is made smaller than the discharge starting electric field obtained based on the Paschen's discharge curve, so that no discharge occurs in the cleaning electric field.

In the image forming apparatus of the present invention, the pressure difference between the air pressure inside the air flow opposing member and the atmospheric pressure for sucking or blowing out the air flow with respect to the powder control member,
It is characterized by being set to 15 mm (H ₂ O) or less. In the image forming apparatus of the present invention, the pressure difference between the pressure inside the airflow facing member and the atmospheric pressure is set to 15 mm (H ₂ O) or less, so that a low-noise, low-cost fan or the like is used as the airflow generation means. Can be used.

In the image forming apparatus according to the present invention, in a state where the airflow is generated by the airflow generation unit,
The cleaning electric field forming means starts forming a cleaning electric field. In the image forming apparatus of the present invention, the airflow is generated by the airflow generating means,
In the state where the cleaning of the powder by the air current is performed, the cleaning electric field is started by the cleaning electric field means and the cleaning by the electric field is added. Unlike the case where the cleaning by the electric field is started, the powder does not adhere to the surface of a member such as the airflow opposing member (opposing electrode member) constituting the cleaning electric field forming means.

In the image forming apparatus of the present invention, the gap between the air flow opposing member and the powder control member when the air flow port is at the opposing position is larger than when the air flow port is at the separated position. It is characterized by being narrowed. In the image forming apparatus of the present invention, by narrowing a gap between the airflow facing member and the powder control member when the airflow port is at the facing position, the airflow port is located at the separated position. As compared with the case where the gap is the same, the cleaning by the air flow can be performed more efficiently.

In the image forming apparatus according to the present invention, a gap between the airflow facing member and the powder control member when the airflow port is at the facing position is set to 0.3 mm or less. It is. In the image forming apparatus of the present invention, by setting the gap to 0.3 mm or less, it is possible to reduce the size of airflow generating means such as a fan that generates a predetermined airflow in a space adjacent to the powder control member, and The magnitude of the voltage for forming the cleaning electric field in the space can be reduced to a safe level.

In order to achieve the second object, in the cleaning apparatus of the present invention, an airflow generating means for generating an airflow in a space adjacent to the object to be cleaned, and moving the powder in a direction away from the object to be cleaned. Cleaning electric field forming means for forming a cleaning electric field to be formed in the space. In the cleaning device of the present invention, an airflow is generated in a space adjacent to the surface to be cleaned, and the powder adhering to the surface to be cleaned is cleaned while being separated from the surface. Simultaneously with the cleaning by the air flow, a cleaning electric field is formed to move the powder by electrostatic force in a direction away from the surface to be cleaned, and the powder adhering to the surface to be cleaned is separated from the surface by the cleaning electric field. While cleaning. As described above, the airflow and the electrostatic force are combined, and the cleaning by the airflow and the cleaning by the electrostatic force are simultaneously performed. In the cleaning device of the present invention, in order to obtain better cleaning performance, the cleaning electric field may be formed by a voltage obtained by superimposing a DC voltage on an AC voltage, or the frequency of the AC voltage may be improved by a good cleaning performance. It is preferable to set within the range specified. Further, in order to more reliably prevent the generation of discharge due to the cleaning electric field, a gap between a pair of electrodes where the cleaning electric field is formed, a potential difference between the electrodes, and a cleaning electric field are formed based on a Paschen curve. It is desirable to set the pressure and the like of the space to be discharged to a size that does not cause discharge. Further, in order to enhance the cleaning efficiency, it is preferable that the direction of movement of the powder moving by the air current is substantially the same as the direction of the powder moving by the cleaning electric field.

In order to achieve the third object, an image forming apparatus according to the present invention is directed to an image forming apparatus, comprising: charging a chargeable powder as an image forming substance via a powder control member having a powder passage hole; An image forming unit that forms an image on the recording medium by selectively passing powder that is to fly toward the recording medium through the powder passage hole based on image information A plurality of sets, a belt member movable along an image forming position of each image forming unit, and a belt driving unit for driving the belt member, wherein a cleaning device for cleaning the powder control member is provided. Is movably provided between a cleaning position facing the powder control member and a retracted position separated from the image forming position. Here, the belt member includes:
Not only the belt member for conveying the recording medium, but also a belt member as an intermediate image carrier for temporarily carrying an image composed of powder before being transferred to the recording medium is included. In the image forming apparatus of the present invention, when an image is formed, a cleaning device for cleaning each powder control member is moved to a retracted position separated from the image forming position of each image forming unit, so that recording by each image forming unit is performed. An image can be formed on a medium. Then, at the time of non-image formation, the cleaning device is sequentially moved to a cleaning position facing each powder control member, thereby cleaning each powder control member.

In the image forming apparatus of the present invention, the cleaning device is configured to be movable along the belt member, and driving means for moving the cleaning device between the retracted position and the cleaning position is provided. It is characterized by having been provided. In the image forming apparatus of the present invention, at the time of image formation, a cleaning device for cleaning the powder control member by the driving unit is driven along the belt member, and is moved to a retracted position separated from the image forming position. An image can be formed on a recording medium by each image forming unit. Then, at the time of non-image formation, cleaning of each powder control member is performed by sequentially moving the cleaning device along the belt member to a cleaning position facing each powder control member by the driving unit.

In the image forming apparatus of the present invention, the cleaning device is configured to be able to take a driven state following the belt member and a driven released state in which the driven is released, and the driven state of the cleaning device is provided. And a driven switching means for switching between the driven release state and the driven release state. In the image forming apparatus of the present invention, when the cleaning device is moved during non-image formation, the state of the cleaning device is switched to a driven state in which the cleaning device is driven by the belt member by driven switching means, and the belt member is driven. The cleaning device can be sequentially moved to a cleaning position facing the powder control member of each image forming unit. When the cleaning device is moved to the retracted position during image formation, the driven switching device switches the state of the cleaning device to a driven release state in which the driven device with the belt member is released, and the image on the recording medium is removed. The cleaning device is prevented from moving from the retracted position regardless of the driving of the belt member for forming.

In the image forming apparatus of the present invention, the cleaning device is wrapped around the plurality of rotating members so that a part of the belt member is detoured in a direction opposite to a direction capable of facing the powder control member. And a cleaning member disposed in an area where the belt member is detoured. In the image forming apparatus of the present invention, the cleaning members arranged in the detour region of the belt member can be sequentially moved to the cleaning positions facing the powder control members of the respective image forming units.

In the image forming apparatus according to the present invention, one of the rotating members of the belt detour means is used also as the cleaning member. In the image forming apparatus of the present invention, the number of components is further reduced by using one of the rotating members of the belt detour means as the cleaning member.

The image forming apparatus according to the present invention includes: a powder carrier for supporting a chargeable powder as an image forming substance; a counter electrode member arranged to face the powder carrier; Flying electric field forming means for forming a flying electric field for causing the powder on the body support to fly toward the counter electrode member; and a flying electric field forming means between the powder support and the counter electrode member. Each image forming unit is configured by using a powder passage member for controlling the flight of powder to the counter electrode member and a powder control member having a control electrode around the powder passage hole. An image forming apparatus provided with a power supply for applying a voltage to the control electrode based on the control signal, wherein a retracting means for moving the counter electrode member to a retracted position separated from a moving path of the cleaning device is provided. Things. In the image forming apparatus of the present invention, at the time of non-image formation, the retreating means moves the counter electrode member, which is disposed in each image forming section so as to face the powder carrier, to the retreat position separated from the movement path of the cleaning device. This ensures that the cleaning device can be moved to the cleaning position in each image forming section without interference between the cleaning device and the counter electrode member.

[0036] The image forming apparatus of the present invention includes a powder carrier for supporting a chargeable powder as an image forming substance, a counter electrode member arranged to face the powder carrier, and Flying electric field forming means for forming a flying electric field for causing the powder on the body support to fly toward the counter electrode member; and a flying electric field forming means between the powder support and the counter electrode member. Each image forming unit is configured by using a powder passage member for controlling the flight of powder to the counter electrode member and a powder control member having a control electrode around the powder passage hole. An image forming apparatus provided with a power supply for applying a voltage to the control electrode based on the control member, wherein the belt member is formed using a conductive material and is used as a common counter electrode member facing each powder carrier. It is characterized by having been. In the image forming apparatus of the present invention, at the time of image formation, the powder on each powder carrier is caused to fly toward a common counter electrode member formed of a conductive material as a belt member.

In the image forming apparatus according to the present invention, a belt unit configured to include the belt member is provided on a side opposite to the retracted position with a cleaning position for each of the powder control members interposed therebetween. It is characterized by being provided so as to be able to swing about an axis. In the image forming apparatus of the present invention, a belt unit configured to include a belt member during non-image formation is provided with a swing unit provided on a side opposite to the retreat position with a cleaning position for each of the powder control members interposed therebetween. By oscillating about the moving axis, a cleaning device for cleaning each powder control member can be moved to the cleaning position without contacting the belt member.

The image forming apparatus according to the present invention includes a powder carrier for supporting a chargeable powder as an image forming substance, a counter electrode member arranged to face the powder carrier, and Flying electric field forming means for forming a flying electric field for causing the powder on the body support to fly toward the counter electrode member; and a flying electric field forming means between the powder support and the counter electrode member. Each image forming unit is configured by using a powder passage member for controlling the flight of powder to the counter electrode member and a powder control member having a control electrode around the powder passage hole. An image forming apparatus provided with a power supply for applying a voltage to the control electrode based on the control signal, wherein the counter electrode member is swingable integrally with the belt unit. In the above-described image forming apparatus, in the configuration including the counter electrode member disposed so as to face the powder carrier, the counter electrode member can be swung integrally with the belt unit so that each of the powders is formed. A path for moving a cleaning device for cleaning the body control member to the cleaning position without interfering with the belt member and the counter electrode member is secured.

In order to achieve the fourth object, an image forming apparatus according to the present invention comprises a powder carrier for supporting a chargeable powder as an image forming substance, and a powder carrier opposed to the powder carrier. Electrode member arranged as described above, flying electric field forming means for forming a flying electric field for causing the powder on the powder carrier to fly toward the counter electrode member, the powder carrier and the counter electrode A powder control member having a powder passage hole for controlling the flight of the powder from the powder carrier to the counter electrode member with respect to the member, and a control electrode around the powder passage hole; A belt member movable along an image forming position of each image forming unit, a belt driving unit for driving the belt member, and applying a voltage to the control electrode based on image information. An image forming apparatus having a power supply, An opening for cleaning is formed, and the counter electrode member is also used as a cleaning member for cleaning the powder control member through the opening. In the image forming apparatus of the present invention, the cleaning opening formed on the belt member is opposed to the powder control member, and the powder control member is cleaned by the counter electrode member also serving as the cleaning member via the opening.

In the image forming apparatus of the present invention, the distance between the outer peripheral surface of the portion used for cleaning and the center of rotation is the distance between the outer peripheral surface of the other portion and the center of rotation as the counter electrode member also serving as the cleaning member. It is characterized in that a rotating member longer than the rotating member is used, and a rotation driving means for rotating the rotating member is provided. In the image forming apparatus of the present invention, during non-image formation, the counter electrode member also serving as a cleaning member is rotated so that the outer peripheral surface having a long distance from the rotation center of the counter electrode member is opposed to the powder control member. The powder control member can be easily cleaned through the opening. During image formation, the counter electrode member is rotated so that the outer peripheral surface of the counter electrode member having a short distance from the center of rotation is opposed to the powder control member so as not to interfere with the belt member.

In the image forming apparatus according to the present invention, the edge of the belt member is reinforced with a reinforcing material. In the image forming apparatus of the present invention, the durability of the belt member is improved by reinforcing the edge of the belt member having the opening for cleaning with a reinforcing material.

In the image forming apparatus according to the present invention, an edge of the opening of the belt member is reinforced with a reinforcing material. In the image forming apparatus of the present invention, the durability of the belt member is improved by reinforcing the edge of the opening of the belt member with a reinforcing material.

In the image forming apparatus of the present invention, when the cleaning device faces the powder control member, the cleaning device generates an airflow in a space adjacent to the powder control member and moves away from the powder control member. An apparatus for forming a cleaning electric field for moving the powder in a direction is used. In the image forming apparatus of the present invention, at the time of non-image formation that does not affect the image on the recording medium, the cleaning device is sequentially opposed to each powder control member, and an airflow is generated in a space adjacent to the powder control member, Cleaning is performed while removing the powder adhering to the surface of the powder control member from the surface. Simultaneously with the cleaning by the air flow, a cleaning electric field is formed to move the powder by electrostatic force in a direction away from the powder control member, and the powder adhering to the surface of the powder control member is removed by the cleaning electric field. Clean while removing from the surface. As described above, the airflow and the electrostatic force are combined, and the cleaning by the airflow and the cleaning by the electrostatic force are simultaneously performed.

[0044]

[Detailed description]

Hereinafter, embodiments of the present invention will be described with reference to the drawings. First Embodiment FIG. 1 is a perspective view illustrating a schematic configuration of a main part of an image forming apparatus according to a first embodiment. This image forming apparatus uses a toner that is a chargeable powder as an image forming substance,
The apparatus includes a sleeve-shaped toner carrier 1 as a powder carrier, a sleeve-shaped counter electrode member 2 arranged to face the toner carrier 1, a toner control member 3 as a powder control member, and the like. The toner carrier 1 is disposed inside a toner container 4 containing toner. The toner carrier 1 is provided on the surface of the toner carrier 1 when a known electrophotographic image forming apparatus carries toner on a developing roller. The toner can be carried by any known technique. In the present embodiment, the toner that has been negatively charged by friction between the doctor blade 5 or a toner supply member (not shown) and the toner carrier 1 is carried on the toner carrier 1 by electrostatic force. By regulating, a toner layer is formed.

The toner control member 3 is attached so as to close an opening formed in a lower wall portion of the toner container 4. As shown in FIG. 2, the toner control member 3 controls a plurality of toners between the toner carrier 1 and the opposing electrode member 2 so as to control the flying of toner from the toner carrier 1 to the opposing electrode member 2. It has a toner passage hole (hereinafter, referred to as “hole”) 31 as a powder passage hole and a ring-shaped control electrode 32 formed around each hole. The diameter φh of the holes 31 and the pitch Ph between the holes 31 in a direction perpendicular to the conveying direction of the recording paper 6 as a recording medium (the axial direction of the toner carrier 1) are determined.
Is set according to the resolution of the image to be formed. In this embodiment, the resolution is 300d
In order to form an image of about pi, a hole 31 having a diameter φh of 0.160 mm and a pitch Ph of 0.0845 were formed on a substrate made of polyimide having a thickness of 0.075 mm.
mm. Eight rows (31-1 to 31-8) of the holes 31 are formed in a region where the width W of the recording paper 6 in the conveying direction is about 2 mm.
There are 300. Around each hole 31, an electrically independent ring-shaped control electrode 32 is formed, and each control electrode 32 is connected to a power supply circuit for applying a voltage according to image information.

FIG. 3 is an enlarged schematic diagram of an image forming section in which the toner carrier 1 and the counter electrode member 2 face each other with the toner control member 3 interposed therebetween. The toner carrier 1 is grounded, and forms a flying electric field between the toner carrier 1 and the counter electrode member 2 for causing the toner 7 carried on the toner carrier 1 to fly toward the counter electrode member 2. A power supply 8 as a flying electric field forming means is connected. The power supply 8 causes the toner 7 to be applied to the opposite electrode member 2.
, Ie, a positive DC high voltage is applied. A power supply (hereinafter referred to as “image power supply”) 9 for applying a control voltage generated based on image information to each control electrode 32 is provided between the toner carrier 1 and each control electrode 32 of the toner control member 3. Is connected. The image power supply 9 applies independent image signal voltages to the control electrodes 32 based on image information. The distance Li between the control electrode 32 of the toner control member 3 and the counter electrode member 2 is 0.4 mm, the distance Lk between the control electrode 32 and the toner carrier 1 is 0.05 mm, and the peripheral speed of the toner carrier 1 is 150 mm / sec, conveyance speed of the recording paper 6 is 50 mm / sec
c respectively.

FIG. 4 is a schematic diagram showing a flying state of the toner. For example, the toner carrier 1 is grounded, a high DC voltage of +1.2 kV is applied to the counter electrode member 2, and the control voltage 32 is +
When 325 V is applied for 0.4 msec, the toner 7 on the toner carrier 1
An electric field of × 10 ⁶ V / m acts. As a result of the action of the electric field, the Coulomb force applied to the toner 7 exceeds the sum of the adhesion force and the mirror image force acting between the toner 7 and the toner carrier 1, and the toner 7 moves toward the counter electrode member 2. The recording paper that has passed through the hole 31 of the toner control member 3 and continues to fly by the flying electric field formed by the voltage applied to the counter electrode member 2, and is conveyed on the counter electrode member 2. 6 stops, and an image is formed on the recording paper 6.

As described above, an image can be formed on the recording paper 6 by using the image forming apparatus having the above configuration. However, if the image forming operation is repeated, the surface of the toner The toner may adhere to the surface in the vicinity of No. 32, making it impossible to control the target toner flight.

FIGS. 5A and 5B are explanatory diagrams for explaining how toner adheres and accumulates on the surface of the toner control member 3 on the counter electrode member 2 side. Toner 7
When the flying state of the toner 7 is projected and observed with a high-speed camera, not only the toner 7 is flying one by one, but also some of the toner 7 are seen flying together (hereinafter, this toner 7). A cluster is called a "cluster." As shown in FIG. 5A, a part of the toner 7 constituting the cluster is charged not to the normal polarity (minus polarity in this embodiment) but to the opposite polarity (plus polarity in this embodiment). (Hereinafter, the toner charged to the opposite polarity to the normal polarity is referred to as “Wrong Sign”
Toner ", abbreviated as" WST "). The reason why the WST flies against the electric field is that the adhesive force acting between the surrounding normally charged toner (negatively charged toner) is stronger than the electrostatic force generated by the electric field acting on the WST. Seems to be.

As shown in FIG. 5B, when the cluster hits the recording paper 6, W
ST 7 ′ is released from the binding of the normally charged toner (negatively charged toner) 7, flies back by electrostatic force due to the electric field, and adheres to the surface near the control electrode 32 around the hole 31 of the toner control member 3. This is the mechanism by which the toner (WST) 7 ′ charged to a polarity opposite to the normal polarity is deposited on the surface of the toner control member 3 on the recording paper 6 side. As a result of the experiments by the present inventors, it has been found that the amount of the deposited toner is 3 to 5% of the total flying toner. . Also, without cleaning the toner accumulated on the surface of the toner control member,
It was found that if the image formation on the recording paper 6 was continued one after another, the hole 31 of the toner control member 3 was clogged with less than ten sheets, and a part of the image was lost. At this time, the accumulated amount of the toner was about 15 to 30 mg. From this result, it is clear that the toner attached to the surface of the toner control member 3 must be cleaned every time one or a specific number of images are formed.

Therefore, in the present embodiment, a cleaning device that cleans toner adhered to the surface of the toner control member 3 as the surface to be cleaned is provided. Unlike the conventional cleaning method, this cleaning device performs cleaning by simultaneously applying an air current and an electrostatic force to toner adhered to the surface of the toner control member. In order to realize such cleaning, the cleaning device includes an airflow generating unit that generates an airflow in a space adjacent to the toner control member 3, and a cleaning electric field that moves the toner away from the toner control member 3 by electrostatic force. And a control unit that controls the airflow generating unit and the cleaning electric field forming unit to generate the airflow and form the cleaning electric field during non-image formation.

FIG. 6 is a perspective view showing a configuration example in which the above-mentioned cleaning device is provided on the above-mentioned counter electrode member 2 from the viewpoint of miniaturization of the device. That is, the counter electrode member 2 is used not only for forming a flying electric field during image formation but also as a part of a cleaning device during non-image formation. As shown in FIG. 6, the airflow generating means of this cleaning device includes an opposing electrode member 2 which also serves as an airflow opposing member having an airflow port for sucking or blowing airflow to / from the toner control member 3, and the opposing electrode member. An airflow generation source 10 such as a fan connected to an end of the airflow generating device 2 is provided. The counter electrode member 2 is configured to be rotatable, and a slit 2a as the air flow port is formed on an outer peripheral surface thereof along a rotation axis. In the present embodiment, the airflow source 1
At 0, the air inside the counter electrode member 2 is sucked in. In a steady state, the inside of the counter electrode member 2 is set to a negative pressure lower than the atmospheric pressure so that the air is sucked from the slit 2a.

Further, the cleaning electric field forming means is provided with the control electrode 3 of the toner control member 2.
2, a cleaning electrode 11 formed in a convex shape around the slit 2a of the counter electrode member 2, and a cleaning for applying a voltage to the cleaning electrode 11 for forming a cleaning electric field between the cleaning electrode 11 and the control electrode 32. It is configured as a power supply for use. As the cleaning power source, a power source 8 for applying a voltage for forming the flying electric field is used. The power supply 8 is not only a DC voltage for forming the flying electric field, but also an AC voltage (hereinafter referred to as “DC + AC voltage”) on which a DC voltage is superimposed in order to more efficiently remove and clean toner on the toner control member 3. "
) Can be applied. In this embodiment, the polarity of the toner mainly attached to the surface of the toner control member 3 is positive, and an air current is generated so as to suck air from the slit 2a. Is applied. Further, the maximum potential difference between the control electrode 32 of the toner control member 3 and the cleaning electrode 11 on the counter electrode member 2 side at the time of cleaning is set so that discharge does not occur. The potential difference at which such discharge does not occur can be determined based on the Paschen's discharge curve, the gap between the control electrode 32 and the cleaning electrode 11, and the pressure in the region where the cleaning electric field is formed.

The ON / OFF of the air flow source 10 such as the fan and the power supply 8 is controlled by a control unit 12 as a control unit. The control unit 12 includes, for example, a CPU, a RAM,
It can be configured by a microcomputer including a ROM, an I / O interface, and the like. A drive device (not shown) such as a motor is connected to the drive shaft 2b of the counter electrode member 2, and the drive device can be controlled by the control unit 12.

FIGS. 7A and 7B show the toner control member 3 in the image forming apparatus having the above configuration.
FIG. 9 is an explanatory diagram for explaining the cleaning operation of FIG. At the time of image formation shown in FIG. 7A, the counter electrode member 2 is driven such that the slit 2a of the counter electrode member 2 does not face the toner control member 3, and a predetermined distance Is formed, and an image is formed on the recording paper 6. On the other hand, during non-image formation shown in FIG. 7B, the airflow generation source 10 is turned on, and the slit 2a
The opposing electrode member 2 is driven such that the toner is approaching and opposing the toner control member 3. The power supply 8 is turned on after the airflow generation source 10 is turned on and the slit 2 a of the counter electrode member 2 reaches a position facing the toner control member 3. When the slit 2a of the opposing electrode member 2 reaches the position opposing the toner control member 3, air flows as shown by an arrow because the inside of the opposing electrode member 2 has a negative pressure. Further, a DC + AC voltage is applied to the cleaning electrode 11 provided around the slit 2a, and a cleaning electric field is formed to move the positively charged toner on the toner control member 3 toward the slit 2a. The air flow and the cleaning electric field act simultaneously to clean the surface of the toner control member 3. The toner to be cleaned includes not only the toner clogged in the hole 31 of the toner control member 3 but also the toner deposited on the surface of the toner control member on the side of the counter electrode member 2.

As described above, according to the image forming apparatus of the present embodiment, the cleaning by the airflow and the cleaning by the electrostatic force are performed on the toner control member 3 at the same time. Even with a small airflow source,
Good cleaning performance can be obtained. For example, small fans commonly used in office equipment such as printers, copiers and personal computers use fans as airflow sources,
Even when a negative pressure of about 15 mm (H ₂ O) is generated, good cleaning performance can be obtained. Further, as compared with the case where cleaning is performed only by an electric field, a cleaning electric field can be formed at a safer low voltage where discharge does not occur, and good cleaning performance can be obtained in a state where discharge does not occur. Furthermore, according to the image forming apparatus of the present embodiment, since no magnetic force is used for cleaning the toner control member 3, good cleaning performance can be obtained even for non-magnetic toner. Further, according to the image forming apparatus of the present embodiment, since the cleaning by the air current and the electric field is performed during non-image formation, the image formed on the recording paper 6 is the same as when cleaning is performed during image formation. There is no fear of disturbing.

Example Next, a more specific example of the cleaning device employed in the image forming apparatus according to the present embodiment will be described together with a comparative example. In the following Examples and Comparative Examples,
An aluminum roller having a diameter of 38 mm was used as the toner carrier 1 and an aluminum roller having a diameter of 50 mm was used as the counter electrode member 2. A slit 2a having a width of 1 mm was formed in a part of the outer peripheral surface of the counter electrode member 2. Further, the opposing electrode member 2 and the toner control member 3 were opposed to each other with a gap of 0.4 mm.

Example 1 The area around the slit 2 a of the counter electrode member 2 was 0.2 m as the cleaning electrode 11.
m so that the gap between the surface of the cleaning electrode 11 and the surface of the toner control member 3 is 0.2 mm. Further, a fan was connected to the counter electrode member 2 as an airflow generation source, and the inside of the counter electrode member 2 was set to a negative pressure of about 15 mm (H ₂ O). Then, the counter electrode member 2 having a negative pressure inside is rotated at 200 msec for one rotation, and the slit 2a of the counter electrode member 2 comes close to the surface of the toner control member 3 and opposes during the rotation. The toner on the toner control member 3 was cleaned by the force of the sucked air flow. The counter electrode member 2 is 200 ms
Since one rotation is performed at c, the cleaning time is estimated to be about 10 msec. The DC + AC voltage applied to the cleaning electrode 11 of the counter electrode member 2 is:
Nine types of conditions shown in Table 1 below were set. In Table 1, Vdc (V) is the value of the DC component, and Vpp (V) and f (kHz) are the peak-to-peak voltage and frequency of the AC component. The above-described airflow is generated for a substantially constant amount of toner adhered to the surface of the toner control member 3, and a cleaning test according to the so-called L9 experimental design method is performed under the conditions of applying the nine types of voltages shown in Table 1. The amount m (mg) of toner remaining after cleaning at the time of cleaning was measured. The measurement results are also shown in Table 1. FIG. 8 is a diagram showing a factor effect in a cleaning test according to the L9 experimental design method of the first embodiment.

[0059]

[Table 1]

The optimum combination of cleaning conditions obtained from the L9 experimental design method shown in Table 1 and FIG. 8 is Vdc = 400 V, Vpp = 1000 V, and f = 2.5 kHz, and the estimated residual toner amount is 0. It was 15 mg. In fact, the result measured under these optimum conditions was 0.2 mg. Further, continuous image formation was performed on 1,000 sheets under the optimum conditions, but no clogging of the hole 31 of the toner control member 3 occurred. That is, the negative pressure (15 mm (H ₂ O)) created by the fan used for office equipment, and A
By combining the C + DC electric field, the toner control member 3 could be stably cleaned. In the first embodiment, the counter electrode member 2 is used as a cleaning unit for cleaning the toner control member 3. However, a cleaning unit is provided independently of the counter electrode member so that the counter electrode member 2 is retracted during cleaning. , And may be replaced with a cleaning unit for cleaning.

In the first embodiment, a DC + AC voltage having a polarity opposite to the polarity of the voltage applied to the cleaning electrode 11, for example, a DC + AC voltage of Vdc = + 400 V and Vpp = 1000 V is applied to the control electrode 32 of the toner control member 3. A similar cleaning electric field is formed in the space between the slit 2a and the toner control member 3 even when the voltage is applied and the counter electrode member 2 is grounded. However, when such a high voltage is applied to the control electrode 32, electronic components such as an IC of an electric circuit connected to the control electrode 32 are destroyed. That is, the voltage for forming the cleaning electric field needs to be applied to the cleaning electrode 11. However, I of the electric circuit connected to the control electrode 32
It is possible to divide a part of the voltage for forming the cleaning electric field to the control electrode 32 side within the range of the withstand voltage of the electronic component such as C.

Further, from the factor and effect diagram of the L9 experiment design method in the cleaning test of the first embodiment (see FIG. 8), regarding the voltage applied to the cleaning electrode 11, (1) it is better to have a DC component, Moreover, it is better that the DC component is large within the range of the cleaning test. (2) It is better that there is an AC component, and that the peak-to-peak voltage is large within the range of the cleaning test. It has been found that the higher the frequency of the AC component is, the higher the frequency is in the range of the cleaning test.

[Embodiment 2] In the present embodiment 2, the limit of the cleaning electric field strength at which no discharge occurs in a state where an air current of a negative pressure of 15 mm (H ₂ O) is generated as in the above-described embodiment 1 is described. In order to know, a cleaning test was performed by the L9 experimental design method under the voltage application conditions shown in Table 2 below.

[0064]

[Table 2]

When the absolute value of the maximum value of the AC + DC voltage applied to the cleaning electrode 11 exceeds 1000 V during the cleaning test, that is, 1250 V, 150
When the voltage is 0 V, discharge occurs between the control electrode 32 of the toner control member 3 and the counter electrode member 3.
The electrode wire was broken and broke. This result can be easily explained from Paschen's discharge curve for a wide gap shown in FIG. That is, the gap 0.2
mm (200 μm), the potential difference 1250 V is near the discharge curve at which discharge starts. As described above, from the results and consideration of the second embodiment, the AC +
It can be seen that the absolute value of the maximum value of the DC voltage must be below the Paschen's discharge curve.

Example 3 As can be seen from Comparative Examples 1 and 2, which will be described later, regarding the effect of the airflow (negative pressure) on the cleaning performance, the gap between the toner control member 3 and the counter electrode member 2 is 0. The effect is much greater at 0.2 mm than at 4 mm. Also, regarding the cleaning electric field, from the Paschen's discharge curve, the maximum voltage that can be applied to the cleaning electrode 11 is about 1300 V when the gap is 0.2 mm and about 2100 V when the gap is 0.4 mm. The cleaning electric fields are 6.5 × 10 ⁶ V / m and 5.2 × 10 ⁶ V / m, respectively. Therefore,
It is again advantageous to set the gap to 0.2 mm.

Therefore, in the third embodiment, first, the diameter of the counter electrode member 2 is increased by 0.2 mm instead of increasing only the cleaning electrode 11, so that the counter electrode member 2 faces the toner control member 3 even during image formation. The gap with the electrode member 2 was reduced from 0.4 mm to 0.2 mm. However, when a large number of sheets were continuously printed in this state, paper jams occurred frequently. Although the gap was widened to 0.3 mm, jams sometimes occurred. Therefore, the gap is returned to 0.4 mm, and the negative pressure in the counter electrode member 2 is reduced to 15 mm (
The H ₂ O), DC + AC voltage (Vdc = -1000V, Vpp = 2000V , f =
2 kHz) was applied to the counter electrode member 2 (cleaning electrode 11) to perform cleaning, and the amount of toner remaining after cleaning was 0.6 mg. When printing was continuously performed on 1,000 sheets under these conditions, clogging occurred on the 900th sheet. Again, the gap was returned to 0.3 mm, and the DC + AC voltage (Vdc = −750 V, V
(pp = 1500 V, f = 2 kHz) was applied to the counter electrode member 2 (cleaning electrode 11) to perform cleaning. As a result, the amount of toner remaining after cleaning was 0.4 mg, and clogging did not occur even after continuous printing of 1,000 sheets. .

As described above, from the result of the third embodiment, in order to perform stable cleaning at a negative pressure of 15 mm (H ₂ O) without causing paper jam, the toner control member 3 during cleaning is required.
It can be seen that it is preferable to make the gap between the counter electrode member 2 (cleaning electrode 11) closer to that at the time of image formation (at the time of paper conveyance). Further, it is understood that the interval is preferably within 0.3 mm.

Fourth Embodiment In a fourth embodiment, a negative pressure of 15 mm (H ₂ O
In the state where the airflow was generated, a cleaning test was performed by the L9 experimental design method under the voltage application conditions shown in Table 3 below. The counter electrode member 2 having the 0.2 mm thick cleaning electrode 11 was used so that the gap between the toner control member 3 and the counter electrode member 2 was 0.2 mm. FIG. 10 is a diagram showing a factor effect in a cleaning test according to the L9 experimental design method of the fourth embodiment.

[0070]

[Table 3]

From the factor and effect diagram of FIG. 10, it can be seen that in the case of the configuration of the fourth embodiment, the polarity of the DC component of the cleaning electric field forming voltage must be opposite to the charging polarity of the toner to be cleaned. Of course, it is also clear that in the case where an air flow is blown to the toner control member 3 instead of sucking in with a negative pressure as in the fourth embodiment, the toner control member 3 must have the same polarity as the toner to be cleaned.

Fifth Embodiment In a fifth embodiment, in order to know the optimum frequency at the cleaning AC voltage, an air flow with a negative pressure of 15 mm (H ₂ O) is generated in the same manner as in the first embodiment. A cleaning test was performed according to the L9 experimental design method under the voltage application conditions shown in Table 4 below. Also in the fifth embodiment, the counter electrode member 2 having the 0.2 mm thick cleaning electrode 11 is formed so that the gap between the toner control member 3 and the counter electrode member 2 is 0.2 mm.
Was used. FIG. 11 is a diagram showing a factor effect in a cleaning test according to the L9 experimental design method of the fifth embodiment.

[0073]

[Table 4]

The optimum value of the frequency of the AC component of the voltage applied to the cleaning electrode 11 is 2 k based on the factor-effect diagram of FIG.
It is about Hz, and it can be seen that it can be used at 0.5 kHz or more and 3.0 kHz or less.

Example 6 During the cleaning tests of Examples 1 to 5, the back surface of the recording paper of the image forming sample was sometimes stained with toner. At first, the cause of the dirt was unknown,
The present inventors have conducted various investigations and found that the counter electrode member 2 for the cleaning operation was
And the power supply 8 for generating the cleaning electric field were turned on at the same time, the distance was long, the cleaning electric field was weak, and even if the negative pressure in the counter electrode member 2 was not generated, the toner control member 3 It has been found that a part of the WST is cleaned and flies to and adheres to the counter electrode member 2, and the adhered toner adheres to the back surface of the recording paper 6 to cause back stain. Therefore, in the sixth embodiment, the DC + AC for cleaning is applied to the counter electrode member 2 at a timing when the slit 2a approaches the WST on the toner control member 3 and a negative pressure is applied thereto. A voltage was applied. As a result, all of the cleaned toner was collected in the counter electrode member 2 under a negative pressure, and the back stain of the recording paper 6 during image formation was eliminated.

[Comparative Example 1] As a comparative example with respect to each of the above examples, in Comparative Example 1, a vacuum pump was connected as a gas flow source to the counter electrode member 2, and the inside of the counter electrode member 2 was set to a negative pressure. .
As shown in FIG. 12A, the cleaning electrode 11 around the slit 2a of the counter electrode member 2 is not formed to be high, and the gap between the surface of the cleaning electrode 11 and the surface of the toner control member 3 is zero. 0.4 mm. The counter electrode member 2 was rotated in a state where the inside of the counter electrode member 2 was under negative pressure, and cleaning was performed with the slit 2a of the counter electrode member 2 and the toner control member 3 facing each other as shown in FIG. . In Comparative Example 1, the negative pressure was increased from 200 mm (H ₂ O) to 90 mm.
The cleaning residual toner amount at that time was measured in three stages up to (H ₂ O) and compared with the value before cleaning to determine the cleaning efficiency. In that condition,
1000 prints were made while cleaning each print, and the lack of images due to clogging was checked. The results are shown in Table 5 below.

[0077]

[Table 5]

From the results in Table 5, it is necessary to set the negative pressure in the counter electrode member 2 to 150 mm (H ₂ O) in order to obtain good cleaning performance with the configuration using no electric field as in Comparative Example 1. It turns out that there is. Further, the negative pressure in the counter electrode member 2 is reduced to 90 mm (H ₂ O).
When the cleaning was performed by rotating the counter electrode member 2 not only once but also many times in the state set as above, the result was almost the same. It can be seen that cleaning is not possible even when the cleaning time is long. Normally, the negative pressure at which a small fan used in OA equipment such as a printer, a copying machine, and a personal computer can be made is 15 mm (H ₂ O). As in Comparative Example 1, 150 mm (
If a large fan or vacuum pump capable of producing a negative pressure of H ₂ O) is used, the size of the apparatus is increased, the cost is increased, and the noise is increased.

Comparative Example 2 In Comparative Example 2, as shown in FIG. 7 of the present embodiment, the circumference of the slit 2 a of the counter electrode member 2 was raised by 0.2 mm to form the cleaning electrode 11, The gap between 11 and the toner control member was reduced from 0.4 mm to 0.2 mm. Then, similarly to the comparative example 1, the negative pressure in the counter electrode member 2 is reduced by 90 m.
The cleaning efficiency and the occurrence of clogging were examined in four steps from m (H ₂ O) to 15 mm (H ₂ O). The results are shown in Table 6 below.

[0080]

[Table 6]

From the results shown in Table 6, the toner control member 3 and the counter electrode member 2 (the cleaning electrode 11
It can be seen that a high negative pressure of 90 mm (H ₂ O) is still required even if the gap with ()) is close to 0.2 mm. Further, it is possible to close the gap, but it is not possible to achieve 98% or more of cleaning without clogging with a negative pressure of 15 mm (H ₂ O). In other words, it can be seen that it is impossible to clean only the air flow within the range of the negative pressure that can be created by the small fan built in the office machine.

Comparative Example 3 In Comparative Example 3, the negative pressure in the counter electrode member 2 was reduced to 0 mm (
H ₂ O), and a cleaning voltage different from +1.2 kV during image formation was applied to the counter electrode member 2 during cleaning. DC voltage V of this cleaning voltage
Table 7 shows the residual toner amount m after cleaning when dc, the peak-to-peak voltage Vpp and the frequency f were changed.

[0083]

[Table 7]

The optimum combination obtained from the L9 experimental design shown in Table 7 is Vdc = −500
V, Vpp = 1000 V, f = 1.5 kHz, and the estimated remaining toner weight at this time is 1.3 mg. Since the remaining toner amount is considered to be 0.4 mg or less in order to perform stable cleaning from Comparative Examples 1 and 2, it is expected that the hole 31 of the toner control member 3 will be clogged immediately under this condition. In fact, clogging occurred on the tens of sheets when continuous printing was performed with the optimum combination. From the above results, it can be seen that it is also impossible to clean only with an electric field.

Second Embodiment FIG. 13 is a front view illustrating a schematic configuration of an image forming apparatus according to a second embodiment. This image forming apparatus directs toner, which is a powder having a charge as an image forming substance, to a recording paper 6 as a recording medium via a toner control member 3 as a powder control member having a toner passage hole. Four sets of image forming units for forming an image on the recording paper 6 by causing the toner to fly toward the recording paper 6 based on the image information to selectively pass through the powder passage holes are provided. ing. Then, each image forming unit 40Y,
It has a paper transport belt 41 as a belt member movable in the direction A in the figure along the image forming positions of 40M, 40C, and 40BK, and a belt driving means for driving the paper transport belt 41. In addition, a paper feed cassette 42 in which the recording paper 6 before image formation is set, a fixing device 43 including a set of fixing rollers for fixing a toner image formed on the recording paper 6, and the like are also provided. A pair of support rollers 44a, 44 around which the belt driving means and the paper transport belt 41 are wound and at least one of which is a driving roller.
b, and a rotary drive device (not shown) for driving the drive roller out of the support rollers 44a and 44b.

The image forming units 40Y, 40M, 40C, and 40BK are respectively a yellow toner (Y), a magenta toner (M), a cyan toner (C), and a black toner (B
K) is used to form a toner image on the recording paper 6. Each image forming unit has substantially the same configuration, and includes a toner carrier 1 on a sleeve as a powder carrier, an opposing electrode member 2 arranged to face the toner carrier 1, and a toner carrier on the toner carrier 1. Electric field forming means for forming a flying electric field for causing the toner to fly toward the counter electrode member 2, and the toner flying from the toner carrier 1 to the counter electrode member 2 between the toner carrier 1 and the counter electrode member 2 And a toner control member 3 having a control voltage around the hole. The flying electric field forming means is constituted by using a power source (not shown) for applying a predetermined voltage between the toner carrier 1 and the counter electrode member 2. Further, a power supply (not shown) for applying a voltage to the control electrode based on image information is provided. It should be noted that reference numerals Y, M, C, and BK corresponding to the respective color toners are given to the reference numerals of the members constituting each image forming unit in FIG. The toner carrier 1 is disposed in a toner hopper 45 containing toner, and is in contact with a replenishing roller 46 for replenishing toner in the hopper 45. Note that the configuration of the toner control member 3 and the control of the toner flight are the same as those of the image forming apparatus of the first embodiment, and a description thereof will be omitted.

In the present image forming apparatus, the cleaning device 50 for cleaning each toner control member 3 is moved between the cleaning position facing each toner control member 3 and the retreat position separated from the image forming device. It is provided movably along the conveyor belt 41. Then, the paper transport belt 41 is wrapped around three rotatable rollers 47 a, 47 b, and 47 c as a rotatable rotator so that a part of the paper transport belt 41 is detoured in a direction opposite to a direction in which the toner transport member 3 can be opposed. I have. A cleaning head 51 as a cleaning member is disposed in a detour area of the paper transport belt 41. When the cleaning device 50 faces the toner control member 3, the cleaning device 50 generates an airflow in a space adjacent to the toner control member 3 and generates a cleaning electric field that moves the toner away from the surface of the toner control member 3. The cleaning head 51 cleans the toner adhered to the toner control member 3 by airflow and electrostatic force in a non-contact manner.
And an electrode (not shown) for forming a cleaning electric field. As shown by an arrow B in the drawing, the toner is sucked together with the air from the airflow port 51a.

The image forming apparatus further includes a drive unit (not shown) as a retracting unit for moving each of the counter electrode members 2 to a retracted position separated from the moving path of the cleaning device 50. When an image is formed by the image forming apparatus having the above-described configuration, the recording paper 6 is fed from a paper feed cassette 42 by a paper feed roller 42a or the like, and is conveyed to an upper portion in the figure through a guide plate (not shown). The recording paper 6 is sent between the opposing electrode member 2, which is an image forming apparatus, and the toner control member 3 provided outside the toner hopper 45 by the conveyance roller pair 48 and the paper conveyance belt 41. In each image forming section 40, the toner carrier 1
The toner of each color which is to fly toward the counter electrode member 2 through the hole of the toner control member is controlled by the control electrode provided around the hole of the toner control member 3, and the toner which has partially fly is The color image adheres to the recording paper 6 on the paper transport belt 41 to form a color image. The recording paper 6 on which the color image has been formed is sent to the fixing device 43, and the toner attached on the recording paper 6 is fixed.

Then, at the time of non-image formation after the recording paper 6 has passed between the counter electrode member 2BK and the toner control member 3BK of the last image forming unit 40BK, the cleaning device 50 is moved by the driving device (not shown) by the arrow. Move in the C direction. With the movement of the cleaning device 50, each counter electrode member 2 located inside the paper transport belt 41 moves to the retracted position on the fixing device 43 side. When the cleaning device 50 moves to the cleaning position, a cleaning electric field is formed by a voltage applied to an electrode (not shown) of the cleaning head 51, and the cleaning electric field causes the toner to separate and move from the surface of the toner control member 3. Airflow port 51a of cleaning head 51 facing control member 3
And the toner is sucked together with the air as shown by the arrow B in FIG. Thereafter, when the cleaning of each toner control member 3 is completed, the cleaning device 50 moves to the retreat position on the left side in the drawing.

As described above, according to the image forming apparatus of the present embodiment, even when the cleaning device 50 that can perform non-contact cleaning without causing damage due to rubbing is used, the cleaning device 50 faces each toner control member 3. The cleaning of each toner control member 3 can be performed by sequentially moving the toner control members 3 to the respective cleaning positions. The member 3 can be cleaned well. Further, since the retreat position of the cleaning device 50 can be set on the moving path of the paper transport belt 41,
The size of the device can be reduced.

Further, according to the image forming apparatus of this embodiment, the cleaning device 50 is sequentially moved to the cleaning position facing each toner control member 3 along the paper transport belt 41, so that each toner control member 3 Is performed, the moving path of the paper transport belt 41 becomes the same as the moving path of the cleaning device 50, and the size of the device can be reduced. Further, according to the image forming apparatus according to the present embodiment, the cleaning head 51 disposed in the detour area of the paper transport belt 41 can be sequentially moved to the cleaning device facing the toner control member 3 of each image forming unit 40. It is not necessary to secure a space for arranging the cleaning head 51 at a position distant from the movement path of the paper transport belt 41, and it is possible to further reduce the number of parts and reduce the size of the apparatus.

In the present embodiment, the rollers 47a that detour the paper transport belt 41,
47b and 47c may be configured so as to be able to assume a rotatable state and a rotation restricted state in which rotation is restricted. In this case, a driven switching mechanism (not shown)
At the time of non-image formation in which the cleaning of the toner control member 3 is performed, the rollers 47a,
7b and 47c are in the above-described rotation restricting state, and the cleaning device 50 is
1 to be driven. Accordingly, the cleaning device 50 can be moved to the cleaning position of each toner control member 3 by rotating and driving the paper transport belt 41. On the other hand, at the time of image formation, the rollers 47a, 47b, and 47c are set in the idling state, and the cleaning device 50 is set in a driven release state in which the driven with the paper transport belt 41 is released. Thereby, the cleaning device 50 can be fixed at the retracted position. As described above, the cleaning device 5 is moved by the movement of the paper transport belt 41.
Since the zero can be moved, there is no need to provide a driving device only for moving the cleaning device 50, and the cost of the device can be reduced. Further, since the retreat position of the cleaning device 50 can be set on the moving path of the paper transport belt 41, the size of the device can be further reduced.

Third Embodiment FIG. 14 is a front view illustrating a schematic configuration of an image forming apparatus according to a third embodiment. This image forming apparatus has substantially the same configuration as the image forming apparatus according to the second embodiment (see FIG. 13), and the same members as those in the second embodiment are denoted by the same reference numerals, and description thereof is omitted. I do. In the image forming apparatus shown in FIG. 14, a cylindrical member 52 is used as a cleaning member for cleaning the toner control member 3, and the cleaning member 52 is used as one of three rollers used as a bypass material of the paper transport belt 41. I also use it. A slit 52a as an air flow port is formed in an outer peripheral portion of the cleaning member 52 facing the toner control member. According to the image forming apparatus of the present embodiment, in particular, since the number of rollers for bypassing the paper transport belt 41 can be reduced by one, the number of components is further reduced.

Fourth Embodiment FIG. 15 is a front view illustrating a schematic configuration of an image forming apparatus according to a fourth embodiment. The present image forming apparatus has substantially the same configuration as the image forming apparatus according to the above-described embodiment (see FIG. 13). . In the image forming apparatus shown in FIG. 15, the paper transport belt 41 is formed of a conductive material (for example, Ni) without providing the counter electrode member 2 used in the image forming apparatus of FIG. 41 is also used as a counter electrode member. As in the apparatus shown in FIG. 14, a cylindrical member 52 is used as a cleaning member for cleaning the toner control member 3.

According to the image forming apparatus of this embodiment, the number of components can be further reduced because the paper transport belt 41 is used as a common counter electrode member formed of a conductive material. Further, unlike the image forming apparatus of FIG. 13, there is no need to retract the counter electrode member 2 during cleaning, and it is not necessary to secure a space for retracting the counter electrode member 2. Furthermore, since the retreat space of the cleaning device 50 can be set on the fixing device 43 side, it is necessary to move the cleaning device 50 to the retreat position on the sa side in the drawing after the cleaning in the last image forming unit 40BK is completed. Disappears. Therefore, the cleaning time can be reduced, and the speed of the image forming apparatus can be substantially increased. In the case where the paper transport belt 41 is formed of a conductive material such as Ni as in the present embodiment, the voltage applied to the paper transport belt 41 easily leaks to the outside and weakens in strength. It is preferable to provide an insulating layer also serving as a reinforcing material on the outer peripheral portion of the conveyor belt 41.

Fifth Embodiment FIG. 16 is a front view showing a schematic configuration of an image forming apparatus according to a fifth embodiment. This image forming apparatus has substantially the same configuration as the image forming apparatus according to the second embodiment (see FIG. 13), and the same members as those in the second embodiment are denoted by the same reference numerals, and description thereof is omitted. I do. In the image forming apparatus shown in FIG. 16, a cleaning device 50 is installed outside a belt unit 49 including the counter electrode member 2 and the paper transport belt 41, and the belt unit 40 is a support roller as a swing shaft on the right side in the drawing. (Drive roller) 44b is configured to be able to swing around. When cleaning is performed in this configuration, the belt unit 49 is retracted by swinging about the support roller (drive roller) 44b in the direction of arrow D. Then, the cleaning device 50 is moved in the direction of arrow C, and is opposed to the toner control member of each image forming unit 40. As described above, according to the image forming apparatus of the present embodiment, the cleaning device 50 for cleaning each toner control member 3 can be moved to the cleaning position without making contact with the paper transport belt 41. 41 can be improved in durability.

Sixth Embodiment FIG. 17 is a front view illustrating a schematic configuration of an image forming apparatus according to a sixth embodiment. This image forming apparatus has substantially the same configuration as the image forming apparatus according to the second embodiment (see FIG. 13), and the same members as those in the second embodiment are denoted by the same reference numerals, and description thereof is omitted. I do. In the image forming apparatus shown in FIG. 17, an opening for cleaning is formed in the paper transport belt 41, and the counter electrode member is also used as a cleaning member for cleaning the toner control member via the opening. As the counter electrode member also serving as the cleaning member, the distance between the outer peripheral surface of the portion used for cleaning and the rotation center is longer than the distance between the outer peripheral surface of the other portion and the rotation center. ~ 53BK
And a rotation drive device (not shown) for rotating the eccentric rotation member 53 is provided. When performing cleaning in the present image forming apparatus, the cleaning opening is moved below the toner control member 3 to be cleaned in the paper transport belt 41, and the eccentric rotation member 53 is rotated about 90 degrees in the direction of arrow F. The cleaning is performed by directing the airflow port formed at the position indicated by the arrow E of the eccentric rotation member 53 toward the toner control member 3. Then, all the toner control members 3 are cleaned while sequentially moving the cleaning openings of the paper transport belt 41 to the cleaning positions of the other image forming units 40.

As described above, according to the image forming apparatus according to the present embodiment, each toner control member 3 does not need to be independently provided with a cleaning device dedicated to non-contact cleaning of the toner control member 3 which does not cause damage due to rubbing. Can be easily cleaned. In addition, the eccentric rotating member 5 can be rotated by simply rotating the eccentric rotating member 53 which also serves as a cleaning member.
It is possible to switch between the cleaning state of No. 3 and an image forming possible state which does not interfere with the belt member. In the present embodiment, it is preferable to reinforce the edge of the paper transport belt 41 and the edge of the cleaning opening with a reinforcing material. Thereby, the paper transport belt 41
Can be improved in durability.

In each of the first to sixth embodiments, the image forming apparatus including the toner control member 3 and the like has been described. However, the present invention is not limited to the image forming apparatus including the toner control member 3 and the like. As long as an image forming apparatus forms an image on a recording medium by controlling the flight of toner toward the recording medium by a toner control member, the same effect can be obtained in any type of image recording apparatus. Can be.

Further, the cleaning method and the apparatus according to the present invention transfer a toner image formed on an image carrier such as a photoconductor directly to a recording medium or transfer the toner image to a recording medium via an intermediate transfer body. In the image forming apparatus, the present invention is also applicable to a case where toner adhered to the surface of the image carrier or the surface of the intermediate transfer member is cleaned.

According to the image forming method of the present invention, the cleaning is performed by combining the airflow and the electrostatic force, so that the cleaning ability by the airflow and the cleaning ability by the electrostatic force can be suppressed to a low level even if the cleaning ability by the electrostatic force is suppressed to a low level. Can be completely removed for cleaning. Therefore, it is possible to use a smaller airflow source as compared with the case where cleaning is performed only by the airflow, and to reduce the cleaning electric field by applying a lower voltage as compared with the case where the powder is completely removed only by the electric field. And discharge can be prevented. Further, since no magnetic force is used for cleaning the powder control member, there is an effect that good cleaning performance can be obtained even for non-magnetic powder. Further, since the cleaning by the airflow and the electric field is performed during non-image formation, there is an effect that there is no possibility that the image formed on the recording medium is disturbed unlike the case where cleaning is performed during image formation.

According to the image forming apparatus of the present invention, the cleaning is performed by combining the airflow and the electrostatic force, so that the cleaning ability by the airflow and the cleaning ability by the electrostatic force can be reduced even if the cleaning ability by the electrostatic force is suppressed to a low level. Can be completely removed for cleaning. Therefore, it is possible to use a smaller airflow source as compared with the case where cleaning is performed only by the airflow, and to reduce the cleaning electric field by applying a lower voltage as compared with the case where the powder is completely removed only by the electric field. And discharge can be prevented. Further, since no magnetic force is used for cleaning the powder control member, there is an effect that good cleaning performance can be obtained even for non-magnetic powder.

In particular, according to the image forming apparatus of the present invention, the airflow sucked or discharged from the airflow opening of the airflow opposing member approaching the powder control member adheres to the surface of the powder control member. Since the cleaning is performed by removing the powder, there is an effect that the cleaning by the airflow of the powder control member can be efficiently performed.

Further, in particular, according to the image forming apparatus of the present invention, the flying of the powder from the powder carrier toward the counter electrode member is performed by the powder having the powder passing hole and the control electrode around the powder passing hole. In the case where the control is performed using the body control member, there is an effect that cleaning using a combination of airflow and electrostatic force on the powder control member can be easily performed.

Further, in particular, according to the image forming apparatus of the present invention, the opposing electrode member used for forming a flying electric field for causing the powder to fly from the powder carrier generates an airflow with respect to the powder control member. Since the airflow facing member is also used, the size of the apparatus can be reduced as compared with the case where the airflow facing members are individually provided.

In particular, according to the image forming apparatus of the present invention, the potential of the control electrode of the powder control member can be set to be equal to or lower than the withstand voltage of an electric circuit component such as an IC connected to the control electrode. There is an effect that there is no fear of destroying.

In particular, according to the image forming apparatus of the present invention, the powder is more likely to be detached from the surface of the powder control member as compared with the case where a cleaning electric field consisting only of an electrostatic field is formed. There is an effect that cleaning by the cleaning electric field can be efficiently performed.

In particular, according to the image forming apparatus of the present invention, since a force for reciprocating the powder attached to the powder control member can be reliably applied, the cleaning by the cleaning electric field can be more effectively performed. There is an effect that it can be performed efficiently.

In particular, according to the image forming apparatus of the present invention, the powder moving in the direction away from the powder control member by the cleaning electric field is moved by the airflow in substantially the same direction as the moving direction. This has the effect that more efficient cleaning can be performed.

Further, in particular, according to the image forming apparatus of the present invention, there is an effect that occurrence of discharge due to a cleaning electric field can be prevented.

In particular, according to the image forming apparatus of the present invention, there is an effect that a low-cost, low-cost fan or the like can be used for the airflow generating means.

In particular, according to the image forming apparatus of the present invention, since the powder does not adhere to the surface of a member such as the airflow opposing member (opposing electrode member) constituting the cleaning electric field forming means, the recording medium is prevented. There is an effect that there is no possibility that the surface on the side of the counter electrode member where no image is formed is contaminated with powder.

In particular, according to the image forming apparatus of the present invention, there is an effect that cleaning by airflow can be performed more efficiently.

In particular, according to the image forming apparatus of the present invention, the size of an airflow generating means such as a fan for generating a predetermined airflow in a space adjacent to the powder control member is reduced, and a cleaning electric field is provided in the space. Has an effect that the magnitude of the voltage for forming the voltage can be reduced to a safe level.

According to the cleaning device of the present invention, by performing cleaning by combining the airflow and the electrostatic force, even if the cleaning ability by the airflow and the cleaning ability by the electrostatic force are each suppressed to a low level, the powder on the surface to be cleaned is reduced. The body can be completely removed and cleaned. Therefore, it is possible to use a smaller airflow source as compared with the case where cleaning is performed only by the airflow, and to reduce the cleaning electric field by applying a lower voltage as compared with the case where the powder is completely removed only by the electric field. And discharge can be prevented. In addition, since no magnetic force is used for cleaning the surface to be cleaned, there is an effect that good cleaning performance can be obtained even for non-magnetic 4 powder.

According to the image forming apparatus of the present invention, even when a cleaning device capable of non-contact cleaning of the powder control member which does not cause damage due to rubbing is used, the cleaning device faces each powder control member. Each powder control member can be cleaned by sequentially moving to the cleaning position. There is an effect that the control member can be satisfactorily cleaned.

In particular, according to the image forming apparatus of the present invention, by sequentially moving the cleaning device along the belt member to the cleaning position facing each of the powder control members, the cleaning of each of the powder control members is performed. Is performed, the movement path of the belt member becomes the same as the movement path of the cleaning device, and the size of the device can be reduced.

In particular, according to the image forming apparatus of the present invention, since the cleaning device can be moved by moving the belt member, there is no need to provide a driving device only for moving the cleaning device, thereby reducing the cost of the device. Can be achieved. In addition, since the retracted position of the cleaning device can be set on the movement path of the belt member, the size of the cleaning device can be further reduced.

Further, in particular, according to the image forming apparatus of the present invention, the cleaning members arranged in the detour area where the belt member is partially detoured are sequentially moved to the cleaning position facing the powder control member of each image forming unit. Therefore, there is no need to secure a space for arranging the cleaning member at a location distant from the movement path of the belt member, and there is an effect that the number of parts can be reduced and the apparatus can be downsized.

Further, in particular, according to the image forming apparatus of the present invention, the number of components can be further reduced by using one of the rotating members of the belt detour means as the cleaning member.

Further, in particular, according to the image forming apparatus of the present invention, there is an effect that the cleaning device can be reliably moved to the cleaning position in each image forming unit without interference between the cleaning device and the counter electrode member.

Further, in particular, according to the image forming apparatus of the present invention, in order to fly the powder on each powder carrier, a belt member as a common counter electrode member made of a conductive material is used. Therefore, there is an effect that the number of parts can be further reduced.

Further, in particular, according to the image forming apparatus of the present invention, the cleaning unit for cleaning each powder control member is brought into contact with the belt member by oscillating the belt unit including the belt member. Since the belt member can be moved to the cleaning position without being operated, there is an effect that the durability of the belt member can be improved.

According to the image forming apparatus of the present invention, the cleaning opening formed on the belt member is opposed to the powder control member, and the powder control is performed by the counter electrode member also serving as the cleaning member through the opening. Since the members can be cleaned, each powder control member can be easily cleaned without providing a dedicated cleaning device for non-contact cleaning of the powder control member which does not cause damage due to rubbing. is there.

In particular, according to the image forming apparatus of the present invention, it is possible to switch between the cleaning state of the counter electrode member and the image forming possible state which does not interfere with the belt member only by rotating the counter electrode member also serving as the cleaning member. There is an effect that can be.

In particular, according to the image forming apparatus of the present invention, there is an effect that the durability of the belt member can be improved.

In particular, according to the image forming apparatus of the present invention, even if the cleaning ability by the air current and the cleaning ability by the electrostatic force are each suppressed to a low level, the powder on each of the powder control members is completely removed and the cleaning is performed. it can. Therefore, it is possible to use a smaller airflow source as compared with the case where cleaning is performed only by the airflow, and to reduce the cleaning electric field by applying a lower voltage as compared with the case where the powder is completely removed only by the electric field. And discharge can be prevented. Moreover, since no magnetic force is used for cleaning each powder control member, there is an effect that good cleaning performance can be obtained even for non-magnetic powder.

[0128]

[Industrial applicability]

 The present invention is applicable to a copier, a facsimile, a printer, and the like.

[Brief description of the drawings]

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

FIG. 2 is an explanatory diagram showing a pattern of a control electrode in a toner control member of the image forming apparatus.

FIG. 3 is an enlarged schematic diagram of an image forming unit of the image forming apparatus.

FIG. 4 is a schematic diagram illustrating a flying state of toner in the image forming unit.

FIGS. 5A and 5B are illustrations of toner accumulation on a toner control member in the image forming unit.

FIG. 6 is a schematic configuration diagram of a cleaning device using a counter electrode member in the image forming apparatus according to the embodiment.

FIG. 7A is an explanatory diagram illustrating a state of a counter electrode member during image formation in the image forming apparatus, and FIG. 7B is an explanatory diagram illustrating a state of the counter electrode member during a cleaning operation.

FIG. 8 is a diagram showing a factor and effect in a cleaning test according to the L9 experimental design method in Example 1.

FIG. 9 is a characteristic diagram showing a Paschen's discharge curve.

FIG. 10 is a diagram showing a factor effect in a cleaning test according to the L9 experimental design method in Example 4.

FIG. 11 is a diagram showing a factor effect in a cleaning test according to the L9 experimental design method in Example 5.

12A is an explanatory diagram illustrating a state of a counter electrode member during image formation in the image forming apparatus according to Comparative Example 1, and FIG. 12B is an explanatory diagram illustrating a state of the same-direction electrode member during a cleaning operation. It is.

FIG. 13 is a front view illustrating a schematic configuration of an image forming apparatus according to another embodiment.

FIG. 14 is a front view illustrating a schematic configuration of an image forming apparatus according to still another embodiment.

FIG. 15 is a front view illustrating a schematic configuration of an image forming apparatus according to still another embodiment.

FIG. 16 is a front view illustrating a schematic configuration of an image forming apparatus according to still another embodiment.

FIG. 17 is a front view illustrating a schematic configuration of an image forming apparatus according to still another embodiment.

──────────────────────────────────────────────────続 き Continuation of the front page (71) Applicant's Owneds Brygga 13 421 57 Vestro Froland a Sweden (72) Inventor Kiyoshi Oshima 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Endo Ricoh Co., Ltd. 1-36 Nakamagome, Ota-ku, Tokyo (72) Inventor Crockal, Pale Sweden, 423 61 Torslanda, Buyorlanda Strand 97 (72) Inventor Minoru Suzuki 1-chome Nakamagome, Ota-ku, Tokyo No. 3-6 Ricoh Co., Ltd. (72) Inventor Kiyotaka Ota 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2C162 AE12 AE25 AE31 AE47 AE74 AE84 AE93 AJ05 CA02 CA12 CA24 2H029 DB04 DB07 2H034 BB01 3B116 AA47 AB53 BA08 BA22 BB72 B C01

Claims (29)

[Claims] 1. A chargeable powder as an image forming substance is caused to fly toward a recording medium via a powder control member having a powder passage hole, and based on image information,
In an image forming method for forming an image on the recording medium by selectively passing powder to fly toward the recording medium through the powder passage hole, the powder control member may be used during non-image formation. Forming an air flow in a space adjacent to the cleaning member and forming a cleaning electric field in the space to move the powder in a direction away from the powder control member. 2. A chargeable powder as an image forming substance is caused to fly toward a recording medium via a powder control member having a powder passage hole, and based on image information,
In an image forming apparatus for forming an image on the recording medium by selectively passing a powder to fly toward the recording medium through the powder passage hole, a space adjacent to the powder control member is provided. Airflow generating means for generating an airflow; cleaning electric field forming means for forming a cleaning electric field for moving the powder in a direction away from the powder control member in the space; generation of an airflow by the airflow generating means and the cleaning electric field An image forming apparatus, comprising: control means for controlling formation of a cleaning electric field by a forming means. 3. The image forming apparatus according to claim 2, wherein the airflow generating means comprises: an airflow facing member having an airflow port for sucking or blowing out an airflow with respect to the powder control member; Driving means for driving the airflow opposing member so as to be able to take an opposing position approaching and opposing the powder control member and a separated position separated from the powder control member. The image forming apparatus according to claim 2. 4. An image forming apparatus, comprising: a powder carrier for carrying a powder having a chargeability; an opposing electrode member arranged to face the powder carrier; Flying electric field forming means for forming a flying electric field for causing the powder on the body to fly toward the counter electrode member; and a countermeasure between the powder carrier and the counter electrode member between the powder carrier and the counter electrode member. A powder control member having a powder passage hole for controlling the flight of the powder to the electrode member and a control electrode around the powder passage hole, and a power supply for applying a voltage to the control electrode based on image information. 4. The image forming apparatus according to claim 3, wherein the cleaning electric field forming unit forms the cleaning electric field between a control electrode and a cleaning electrode provided around an airflow port of the airflow facing member. 5. For applying cleaning voltage to the cleaning electrode Source and an image forming apparatus characterized by being configured with. 5. The image forming apparatus according to claim 4, wherein the counter electrode member is formed of a rotatable cylindrical member or a belt member having the air flow port, and is also used as the air flow counter member. Image forming apparatus. 6. The image forming apparatus according to claim 4, wherein the cleaning electric field is mainly formed by a voltage applied to the cleaning electrode. 7. The image forming apparatus according to claim 2, wherein the cleaning electric field is an electric field obtained by superposing an alternating electric field on an electrostatic field. 8. The image forming apparatus according to claim 7, wherein the frequency of the alternating electric field is set to 0.5 kHz or more and 3 kHz or less. 9. The image forming apparatus according to claim 2, wherein the direction of movement of the powder moving by the air current is substantially the same as the direction of the powder moving by the cleaning electric field. An image forming apparatus wherein the direction of the air flow and the direction of the cleaning electric field are set as described above. 10. The image forming apparatus according to claim 2, wherein a maximum value of the cleaning electric field is set to a value smaller than a discharge starting electric field obtained based on Paschen's discharge curve. An image forming apparatus comprising: 11. The image forming apparatus according to claim 2, wherein the air pressure and the atmospheric pressure inside the air flow opposing member for sucking in or blowing out the air flow from / to the powder control member. An image forming apparatus, wherein a pressure difference is set to 15 mm (H ₂ O) or less. 12. The image forming apparatus according to claim 2, wherein the generation of the cleaning electric field by the cleaning electric field forming means is started in a state where the air current is generated by the air flow generating means. Characteristic image forming apparatus. 13. The image forming apparatus according to claim 3, wherein the gap between the air flow opposing member and the powder control member when the air flow port is at the opposing position is defined by the air flow port. The image forming apparatus is characterized in that it is narrower than when it is at the separated position. 14. The image forming apparatus according to claim 3, wherein the gap between the airflow facing member and the powder control member when the airflow port is at the facing position is 0.3 mm. An image forming apparatus having the following settings. 15. An airflow generating means for generating an airflow in a space adjacent to the object to be cleaned, and a cleaning electric field forming means for forming a cleaning electric field in the space for moving powder in a direction away from the object to be cleaned. A cleaning device comprising: 16. A chargeable powder as an image forming substance is caused to fly toward a recording medium via a powder control member having a powder passage hole, and is directed to the recording medium based on image information. A plurality of sets of image forming units for forming an image on the recording medium by selectively passing the powder to fly through the powder passage holes, and moving along the image forming position of each image forming unit An image forming apparatus having a belt member capable of driving the belt member, a cleaning device for cleaning the powder control member, a cleaning position facing the powder control member, and the image forming position. An image forming apparatus provided so as to be movable between a retreat position and a retreat position separated from the retreat position. 17. The image forming apparatus according to claim 16, wherein the cleaning device is configured to be movable along the belt member, and wherein the cleaning device is moved between the retracted position and the cleaning position. An image forming apparatus comprising a driving unit. 18. The image forming apparatus according to claim 17, wherein the cleaning device is configured to take a driven state following the belt member and a driven release state in which the driven is released. An image forming apparatus comprising a driven switching unit for switching between the driven state and the driven release state. 19. The image forming apparatus according to claim 18, wherein said cleaning device is opposite to a direction in which said belt member is wrapped around a plurality of rotating members so that a part of said belt member can face said powder control member. An image forming apparatus comprising: a belt diverter for diverting to a side; and a cleaning member disposed in a region where the belt member is diverted. 20. The image forming apparatus according to claim 19, wherein one of the rotating members of said belt bypass means is also used as said cleaning member. 21. A powder carrier for supporting a chargeable powder as an image forming substance, a counter electrode member arranged to face the powder carrier, and A flying electric field forming means for forming a flying electric field for causing the powder to fly toward the counter electrode member, and between the powder carrier and the counter electrode member between the powder carrier and the counter electrode member. Each of the image forming units is configured by using a powder passage hole for controlling the flight of powder and a powder control member having a control electrode around the powder passage hole, and the control electrode is formed based on image information. 17. The image forming apparatus according to claim 16, further comprising a power supply that applies a voltage to the cleaning device, wherein a retracting unit that moves the counter electrode member is provided at a retracted position that is separated from a moving path of the cleaning device. Forming equipment. 22. A powder carrier supporting a chargeable powder as an image forming substance, a counter electrode member arranged to face the powder carrier, and A flying electric field forming means for forming a flying electric field for causing the powder to fly toward the counter electrode member, and between the powder carrier and the counter electrode member between the powder carrier and the counter electrode member. Each of the image forming units is configured by using a powder passage hole for controlling the flight of powder and a powder control member having a control electrode around the powder passage hole, and the control electrode is formed based on image information. 17. The image forming apparatus according to claim 16, further comprising a power supply for applying a voltage to the belt, wherein the belt member is formed using a conductive material, and is used as a common counter electrode member facing each powder carrier. An image forming apparatus comprising: 23. The image forming apparatus according to claim 16, wherein a belt unit including the belt member is provided on a side opposite to the retracted position with a cleaning position for each of the powder control members interposed therebetween. An image forming apparatus provided so as to be swingable about a swing shaft. 24. A powder carrier for supporting a powder having chargeability as an image forming substance, a counter electrode member arranged to face the powder carrier, and A flying electric field forming means for forming a flying electric field for causing the powder to fly toward the counter electrode member, and between the powder carrier and the counter electrode member between the powder carrier and the counter electrode member. Each of the image forming units is configured by using a powder passage hole for controlling the flight of powder and a powder control member having a control electrode around the powder passage hole, and the control electrode is formed based on image information. 24. The image forming apparatus according to claim 23, further comprising a power supply for applying a voltage to said belt, wherein said counter electrode member is swingable integrally with said belt unit. 25. A powder carrier for supporting a chargeable powder as an image forming apparatus, an opposing electrode member arranged to face the powder carrier, and A flying electric field forming means for forming a flying electric field for causing the powder to fly toward the counter electrode member, and between the powder carrier and the counter electrode member between the powder carrier and the counter electrode member. A plurality of sets of image forming units each including a powder passage hole for controlling the flight of the powder and a powder control member having a control electrode around the powder passage hole are provided. An image forming apparatus comprising: a belt member movable along a position, a belt driving unit for driving the belt member, and a power supply for applying a voltage to the control electrode based on image information. An opening for cleaning is formed, and the counter electrode member is An image forming apparatus characterized by being combined to the cleaning member for cleaning the powder control member via the. 26. The image forming apparatus according to claim 25, wherein the distance between the outer peripheral surface of the portion used for cleaning and the center of rotation is the distance between the outer peripheral surface of the other portion and the center of rotation as the counter electrode member also serving as the cleaning member. An image forming apparatus using a rotating member longer than a distance from the image forming apparatus, and a rotation driving unit for rotating the rotating member. 27. The image forming apparatus according to claim 25, wherein an edge of said belt member is reinforced with a reinforcing material. 28. The image forming apparatus according to claim 25, wherein an edge of said opening of said belt member is reinforced with a reinforcing material. 29. The method of claim 16, 17, 18, 19, 20, 21, 22, 23.
, 24, 25, 26, 27 or 28, the cleaning device generates an airflow in a space adjacent to the powder control member when the cleaning device faces the powder control member. An image forming apparatus using a device for forming a cleaning electric field for moving the powder in a direction away from a body control member.