JP2007163934A - Developing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing apparatus capable of forming an image of high quality over a long period while preventing the deterioration of developer by reducing mechanical stress loaded on the developer and surely electrifying the developer. <P>SOLUTION: Regarding the developing apparatus 6 including a developer carrier 6c that holds and carries non-magnetic one-component developer on the outer peripheral surface thereof, and a supply member 6d for supplying the developer to the developer carrier 6c, a recovery member 6f for recovering the developer remaining on the outer peripheral surface of the developer carrier 6c is provided on the upstream side of the supply member 6d in the rotating direction T2 of the developer carrier 6c, and also, an electrode member 6e composed of a conductive fur brush coming in contact with the outer peripheral surface of the supply member 6d is provided. At least the outer peripheral surface of the supply member 6d is densely formed, so that the developer never enter the inside of the supply member 6d, and an electrical field directed to press the developer against the outer peripheral surface of the supply member 6d is formed between the supply member 6d and the electrode member 6e. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is provided in an image forming apparatus such as a copying machine, a printer, and a facsimile machine, and supplies a developer to an electrostatic latent image formed on an image carrier corresponding to a recorded image to visualize the electrostatic latent image. The present invention relates to a developing device.

  2. Description of the Related Art Conventionally, in electrophotographic image forming apparatuses such as copying machines, printers, and facsimile machines, toner (developer) is carried on the outer peripheral surface of a developing container containing non-magnetic toner of a one-component developer. A substantially cylindrical developer carrier that is conveyed while being transported, a toner supply and recovery member that supplies and collects toner to and from the developer carrier, and the amount of toner that is supplied and carried from the toner supply and recovery member to the developer carrier A developing device having a regulating blade for regulating the above. In this type of developing device, the developer carrier is provided so as to be rotatable about an axis, and is disposed so that a part of the outer peripheral surface is exposed to the outside through an opening formed in the developing container. Has been. The toner supply / recovery member is formed in a substantially cylindrical shape so as to be rotatable about an axis, and the developer container is in a state in which the axial direction coincides with the developer carrying member and the outer peripheral surfaces thereof are in contact with each other. Is disposed on the upstream side in the rotation direction of the developer carrier. The regulating blade is provided on the downstream side in the rotation direction of the developer carrier relative to the toner supply and recovery member and on the upstream side in the rotation direction of the developer carrier relative to the opening of the developer container. Are provided with a predetermined gap.

  The developing device configured as described above is provided with respect to a substantially cylindrical image carrier (photosensitive drum) which is provided so as to be rotatable about an axis and on which an electrostatic latent image of a recorded image is formed. The image forming apparatus is provided such that the outer peripheral surface of the photosensitive drum and the outer peripheral surface of the developer carrying member face each other with a predetermined gap through the opening of the developing container. Then, the toner adhered and conveyed on the outer peripheral surface of the toner supply / recovery member is supplied to the developer carrying member at the contact portion between the outer peripheral surfaces, and passes through the gap with the regulating blade by the rotation of the developer carrying member. At the same time, excess toner is removed to form a thin layer. Then, the toner is further conveyed to the portion facing the photosensitive drum by the further rotation of the developer carrying member, and the toner is supplied to the electrostatic latent image to be visualized.

  On the other hand, in this type of developing device, a bias voltage is applied to the developer carrying member and the toner supply / recovery member to electrically carry the charged toner or to supply the toner by a potential difference between the members. I have to. For this reason, it is necessary to charge non-magnetic one-component toner. In the above developing device, when the toner is supplied from the toner supply / recovery member to the developer carrier, the toner supply / recovery member and the developer carrier are used. The contact portion is rubbed while being subjected to pressure while being frictionally charged. Further, when a thin layer is formed by the regulating blade, the frictional charge is imparted by rubbing while pressure is applied. However, in the developing device that imparts a charged charge to the toner in this way, the toner is deformed by friction under pressure, or the quality of the formed image is deteriorated due to the generation of frictional heat. was there.

  On the other hand, in the developing device disclosed in Patent Document 1, an elastic roller having a sponge layer or a roller having a fur brush is used as a toner supply roller (toner supply / recovery member). Further, in this developing device, the casing (developing container) is formed so that the inner surface portion below the toner supply roller is in contact with the surface (outer peripheral surface) of the toner supply roller, and a power source is connected to the contact portion of the casing. Electrode plate. In the developing device configured as described above, the toner adhering to the gap and the surface of the sponge layer of the toner supply roller and the fur brush and the surface is charged, and the precharged toner is supplied to the developer carrier. It is possible to do.

In the developing device disclosed in Patent Document 2, a contact member is disposed in contact with an outer peripheral surface portion of a supply roller (toner supply / recovery member), and has a function of moving toner to the connection roller side of the connection member. A power source for generating an electric field is connected. Moreover, this contact member is comprised combining the contact material and the base material. In this developing device, the toner adhering to the supply roller passes through the contact portion between the contact material and the supply roller and is charged by the friction, so that it is possible to supply the pre-charged toner to the developer carrier. Has been.
JP-A-8-36299 JP-A-8-87174

  However, in the developing device disclosed in Patent Document 1 described above, since the toner supply roller and the electrode plate are in contact with each other, the toner is pressed when the charged charge is applied to the toner passing through the contact portion. However, there is a problem that the toner is deteriorated. This electrode plate preliminarily charges the toner, and friction charging at the contact portion between the toner supply roller and the developer carrying member is also required. There was a problem that it could not be resolved.

  Further, in the developing device disclosed in Patent Document 1, since toner is also taken into the gap in addition to the surface of the sponge layer and fur brush of the toner supply roller, the toner taken into the gap with respect to the toner on the surface. Has a problem that the toner is not easily charged and is conveyed in a state containing uncharged toner. When the uncharged toner is conveyed in this way, the development transfer becomes worse, causing problems such as background stains and resolution degradation.

  On the other hand, in the developing device disclosed in Patent Document 2, the toner adhering to the supply roller is rubbed while being pressed when passing through the contact portion between the contact material and the supply roller. In addition, since frictional charging is required at the contact portion between the supply roller and the developing roller (developer carrier), there is a problem that toner deterioration cannot be eliminated.

  In addition to this, in the developing devices disclosed in Patent Document 1 and Patent Document 2 described above, among the toner that is triboelectrically charged and carried on the developer carrier, the toner is developed without being supplied to the photosensitive drum. When the toner in the non-image area (residual toner) remaining on the agent carrier reaches the contact portion with the toner supply roller (supply roller), it is mechanically separated by the toner supply roller and collected in the developing container. It is configured as follows. That is, in the developing devices disclosed in Patent Document 1 and Patent Document 2, toner supply to the developer carrying member and toner collection from the developer carrying member are performed by one member of the toner supply roller. Has been. At this time, the electric field formed between the developer carrier and the toner supply roller is, for example, one direction from the toner supply roller toward the developer carrier when the toner is supplied. Residual toner is mechanically peeled away. For this reason, it is necessary to bring the toner supply roller into contact with the developer carrier with a large pressure, and when supplying toner from the toner supply roller to the developer carrier, a large pressure is applied to the toner frictionally charged at this contact portion. There is a problem in that deterioration is more likely to occur due to load.

  In view of the above circumstances, the present invention enables high-quality image formation over a long period of time by reliably charging the developer while reducing the mechanical pressure applied to the developer and preventing deterioration of the developer. An object of the present invention is to provide a developing device.

  In order to achieve the above object, the present invention provides the following means.

  The developing device of the present invention comprises a developer carrying member that is rotated around an axis while carrying a non-magnetic one-component developer on the outer circumferential surface, and the developer carried on the outer circumferential surface while being rotated around an axis. A supply member that supplies the developer carrier, and supplies the developer conveyed by the developer carrier to an image carrier on which an electrostatic latent image of a recorded image is formed, thereby A developing device for visualizing an image, wherein after the developer is supplied to the image carrier, a recovery member for recovering the developer remaining on the outer peripheral surface of the developer carrier, An electrode member made of a conductive fur brush that is provided on the upstream side of the supply member in the rotation direction of the developer carrier and is in contact with the outer peripheral surface of the supply member is provided. Has at least a dense outer peripheral surface Wherein the assumed never developer enters, between the supply member and the electrode member, characterized in that the electric field in a direction for pressing the developer on the outer peripheral surface of the supply member is formed.

  In the developing device according to the present invention, since the conductive fur brush of the electrode member is provided so as to come into contact with the outer peripheral surface of the supply member, the fur brush is applied with a large pressure on the developer attached to the supply member. The developer can be charged by frictional contact without loading. At this time, since an electric field is formed between the supply member and the fur brush so as to press the developer toward the supply member, the charged charge can be reliably applied to the developer, and charged development can be performed. It is possible to reliably carry the agent on the supply member.

  On the other hand, the developer taken in the fur brush may not be charged. However, in the developing device according to the present invention, even when the developer taken in the fur brush is uncharged, the uncharged developer. The charged developer is not pressed against the supply member side by the electric field and remains in the fur brush as it is, and is not transported by the supply member. The agent is transported and development transfer is not deteriorated, and background stains and resolution degradation are not caused.

  Further, since the outer peripheral surface of the supply member is formed so as not to enter the developer, all the developer adhering to the supply member is positioned between the supply member and the electrode member. Therefore, all the developer can be sufficiently charged before being supplied to the developer carrying member. Therefore, like a conventional developing device, the developer enters the gap of the supply member (toner supply roller), and this developer is conveyed in an uncharged state, resulting in poor development transfer, background contamination, and resolution degradation. It is supposed not to invite.

  This eliminates the need to frictionally charge the developer by applying a large pressure to the developer when supplying to the developer carrier or when forming a thin layer with a regulating blade, and supplying the developer to the developer carrier By separately providing a member and a recovery member for recovering the developer from the developer carrier, and separately providing the developer, the developer carrier and the supply member, the developer carrier and the recovery member Therefore, it is not necessary to bring the supply member and the recovery member into contact with the developer carrying member with a large pressure. Therefore, it is possible to dispose the supply member and the recovery member in a non-contact or light contact state with respect to the developer carrier.

  At this time, since the developer is sufficiently charged in advance, the developer can be electrically supplied to the developer carrier, so that the developer can be supplied from the supply member to the developer carrier. The amount (attachment amount) can be set to a predetermined amount corresponding to the potential difference between the supply member and the developer carrying member. As a result, unlike a conventional developing device, a large pressure is not applied to the developer when passing through the regulating blade for regulating the amount of the developer carried on the developer carrying member. In the developing device according to the invention, the regulating blade can be replaced with a leveling member that leveles the developer carried on the developer carrying member.

  According to the developing device of the present invention, since the developer can be sufficiently charged even when the supply member and the recovery member are arranged in a non-contact or light contact state with respect to the developer carrier, Thus, unlike the developing device, a large pressure is not applied to the developer, and the developer can be prevented from being deteriorated. As a result, high-quality image formation can be performed over a long period of time.

  Hereinafter, a developing device according to an embodiment of the present disclosure will be described with reference to FIGS. 1 and 2. This embodiment relates to a developing device provided in an electrophotographic image forming apparatus such as a copying machine, a printer, or a facsimile machine, and performs development using a non-magnetic one-component developer (developer). Therefore, the developing device relates to a developing device.

  As shown in FIG. 1, the image forming apparatus A of the present embodiment is a tandem image forming apparatus, and is provided for each color of magenta, yellow, cyan, and black according to the image signal of the recorded image. Houses a plurality of developing sections 1 for forming toner images of respective colors, an intermediate transfer body 2 having a transfer belt 2a to which toner images formed by the developing sections 1 are sequentially transferred, and a recording body S such as a sheet. Main components are a recording medium conveying means 3 that conveys the recording medium S while taking out the recording medium S from the cassette 3a, and a fixing means 4 that fixes the toner image transferred from the intermediate transfer body 2 to the recording medium S to the recording medium S. It is said that. Here, in this embodiment, the outer peripheral surface of a later-described photosensitive drum 1a that is uniformly charged in the developing unit 1 is scanned and exposed while irradiating a laser beam, and an image of a recorded image is formed on the photosensitive drum 1a. A light traveling device 5 that forms an electrostatic latent image corresponding to a signal is provided in the image forming apparatus A separately from the developing unit 1. Further, the image forming apparatus main body B is configured by combining the above-described components.

  As shown in FIGS. 1 and 2, the plurality of developing units 1 provided for each color are formed in a substantially cylindrical shape and are provided so as to be rotatable about the axis O1 (counterclockwise in the direction of arrow T1). A photosensitive drum 1a, a charger 1b for uniformly charging the outer peripheral surface of the photosensitive drum 1a to a negative charge, and a rotation direction T1 upstream of the photosensitive drum 1a with respect to the charger 1b. It comprises a cleaning device 1c that removes and cleans the developer (hereinafter referred to as toner) adhering to the outer peripheral surface of the photosensitive drum 1a, and a developing device 6 according to the present invention.

  Here, the photosensitive drum 1a, the charger 1b, and the cleaning device 1c are accommodated in one container 1d, and the charger 1b and the cleaning device 1c are provided along the outer peripheral surface on the outer side in the radial direction of the photosensitive drum 1a. The charger 1b is disposed downstream of the cleaning device 1c in the rotation direction T1 of the photosensitive drum 1a. The container 1d is provided with a first opening 1e on the downstream side in the rotation direction T1 of the photosensitive drum 1a of the charger 1b, and the rotation direction of the photosensitive drum 1a with respect to the first opening 1e. A second opening 1f is provided on the upper side downstream of T1. The photosensitive drum 1a has an outer diameter of about 30 mm, for example, and rotates at a peripheral speed of 150 mm / s, and the outer peripheral surface is sequentially exposed to the first opening 1e and the second opening 1f along with the rotation. It is provided to let you. Further, in the container 1d that accommodates the photosensitive drum 1a, the charger 1b, and the cleaning device 1c, the opening end that defines the first opening 1e defines the opening 6b of the developing container 6a described later of the developing device 6. The opening end is detachably engaged with the developing device 6.

  On the other hand, the developing device 6 of the present embodiment supplies the toner carried while being carried to the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 1a by the light running device 5 to form the toner image on the photosensitive drum 1a. A developing roller (developer carrier) 6c to be formed, a supply roller (supply member) 6d for conveying the toner while carrying the toner on the outer peripheral surface and supplying the toner to the developing roller 6c, and an outer peripheral surface of the supply roller 6d An electrode member 6e made of a conductive fur brush for charging the toner adhered to the outer peripheral surface, a collection roller (collection member) 6f for removing the toner adhered to the outer peripheral surface of the developing roller 6c, and a developing container 6a A pair of developer agitating means 6g and 6h that convey the toner inside and agitate the toner to be supplied to the supply roller 6d is housed in the developing container 6a together with the toner. In addition to the above, the developing device 6 is provided with a leveling member 6i for leveling the unevenness of the surface of the toner (toner layer) carried by the developing roller 6c, and a toner adhering to the outer peripheral surface of the collection roller 6f. A scraper 6j to be removed is provided.

  The developing roller 6c is formed in a substantially cylindrical rod shape having an outer diameter of, for example, about 14 mm. For example, a sponge-like conductive urethane is wound around a stainless steel core, and an outer peripheral surface of the conductive urethane is also provided. It is formed by coating with conductive polyimide. The developing roller 6c is provided to be rotatable around an axis O2 along a horizontally extending opening 6b formed on the upper side of the developing container 6a, and an outer peripheral surface of the developing roller 6c extends from the opening 6b. It is provided to face while being exposed to the outside. Further, in the present embodiment, the developing roller 6c is provided such that the outer peripheral surface exposed from the opening 6b is in light contact with the outer peripheral surface of the photosensitive drum 1a, and has a circumferential speed substantially equal to the peripheral speed of the photosensitive drum 1a. It is supposed to rotate clockwise (in the direction of arrow T2) at high speed.

  The supply roller 6d is formed in a substantially cylindrical rod shape having an outer diameter of, for example, about 14 mm. For example, the supply roller 6d is formed by winding a conductive urethane rubber having a rubber hardness of about 50 degrees around a stainless steel core. Yes. The supply roller 6d is formed densely so that the outer peripheral surface of the conductive urethane rubber is treated with ultraviolet rays so that toner does not enter the inside. The supply roller 6d formed in this manner is provided directly below the developing roller 6c so as to be rotatable around the axis O3 while arranging the axis O2 and the axis O3 of the developing roller 6c in parallel. It is arranged in a non-contact state with a gap of about 3 mm. The supply roller 6d rotates clockwise (in the direction of arrow T3) at a peripheral speed that is approximately 1.5 times the peripheral speed of the developing roller 6c.

The electrode member 6e is a conductive fur brush that is configured by implanting conductive fibers on the surface of a substantially flat substrate made of, for example, aluminum. The conductive fiber constituting the fur brush 6e has, for example, an electrical property with a medium yarn resistance of 10 ⁶ to 10 ¹⁰ Ωcm, a single yarn diameter of 10 to 40 μm, and a hair length of 3 to 6 mm. The planting density is 10,000 to 200,000 / inch ² . The fur brush 6e is disposed upstream of the developing roller 6c in the rotation direction T3 of the supply roller 6d, and the base material is fixed to the developing container 6a, and conductive fibers ( The tip of the fur brush 6e) is provided so as to bite about 1 mm and lightly contact the supply roller 6d. At this time, the circumferential width of the supply roller 6d with which the fur brush 6e is lightly contacted is about 7 mm. Here, in this embodiment, the light contact indicates a contact state in which the mechanical pressure is not applied to the toner conveyed to the contact portion and the toner does not deteriorate. The contact state is such that a pressure smaller than cm ² is generated.

  The collection roller 6f is formed in a substantially cylindrical rod shape having an outer diameter of about 10 mm, for example, and is formed by coating the surface of a metal such as stainless steel with a conductive fluororesin with a thickness of about 2 to 50 μm, for example. ing. The collecting roller 6f is lightly in contact with the outer peripheral surface of the developing roller 6c, and is upstream of the supply roller 6d in the rotation direction T2 of the developing roller 6c and from the opening 6b of the developing container 6a. The developing roller 6c is provided on the downstream side in the rotation direction T2 so as to be rotatable about the axis O4. At this time, the collection roller 6f is driven by the rotation of the developing roller 6c, that is, is rotated counterclockwise (in the direction of arrow T4). Further, on the outer peripheral surface located downstream in the rotation direction T4 from the contact portion of the collecting roller 6f with the developing roller 6c, the collecting roller 6f is supported by a support member 6k fixed to the developing container 6a, and the axis O4 of the collecting roller 6f. The tip of a thin plate-shaped scraper 6j extending along the line is provided in light contact.

  The pair of developer agitating means 6g and 6h are, for example, auger screws, and the axes O2 and O3 of the developing roller 6c and the supply roller 6d and the axes O5 and O6 are arranged in parallel below the developing container 6a. It is provided so as to be rotatable around the axes O5 and O6. One developer stirring means 6g is formed with an outer diameter of about 12 mm, for example, and is provided directly below the supply roller 6d with a predetermined interval. The other developer stirring means 6h is formed with an outer diameter of about 8 mm, for example, and is provided obliquely above the upstream side in the rotation direction T3 of the supply roller 6d with respect to one developer stirring means 6g. . Here, the non-magnetic toner of the one-component developer is accommodated below the supply roller 6d of the developer container 6a, and the other developer agitating means 6h is accommodated by the rotation around the axis O6. The toner can be conveyed toward one developer stirring means 6g side while conveying the toner in one direction of the axis O6. On the other hand, the other developer stirring means 6h conveys the toner in the one direction in the direction of the axis O6, whereas the one developer stirring means 6g has the toner in the direction opposite to the one direction in the direction of the axis O5. It can be conveyed toward the supply roller 6d located above while being conveyed. Here, in order to prevent the toner from being directly conveyed to the supply roller 6d side by the other developer stirring means 6h, the developing container 6a is provided with a gap between the supply roller 6d and the other developer stirring means 6h. A partition wall 6m is provided.

  The leveling member 6i is formed, for example, by coating a conductive polyimide on the surface of a sponge-like conductive urethane. The leveling member 6i has the surface lightly contacted with the developing roller 6c, and is downstream of the supply roller 6d in the rotation direction T2 of the developing roller 6c and more than the opening 6b of the developing container 6a. Is fixed to the upstream side in the rotation direction T2 while being supported by the developing container 6a.

  In the developing device 6 configured as described above, the opening end that defines the opening 6b of the developing container 6a has an opening that defines the first opening 1e of the container 1d that accommodates the photosensitive drum 1a and the like. The developing unit 1 is configured integrally with the end while being detachably engaged. Further, the developing unit 1 is provided with an opening (not shown) for irradiating the photosensitive drum 1a with laser light emitted from the light running device 5. Further, in the plurality of developing containers 6a of the plurality of developing units 1, toner storage tanks 8b, 8c, 8y, and 8m that store toner for each color provided in the image forming apparatus A separately from the developing units 1, respectively. Are connected to each other, and toner is sequentially supplied in accordance with a decrease in toner in the developing container 6a.

  On the other hand, in the developing device 6 of the present embodiment, as shown in FIG. 2, the first bias voltage applying means 10 is provided on the developing roller 6c, the second bias voltage applying means 11 is provided on the supply roller 6d, and the electrode member (fur brush). ) 6e is provided with third bias voltage applying means 12 respectively. These bias voltage applying means 10, 11, and 12 are configured to include power supplies 10 a, 11 a, and 12 a, respectively, and the power supplies 10 a and 12 a of the first bias voltage applying means 10 and the third bias voltage applying means 12 are respectively DC. The potential of the developing roller 6c is, for example, DC-300V, and the potential of the fur brush 6e is, for example, DC-1200V. On the other hand, the power supply 11a of the second bias voltage applying means 11 is a direct current and alternating current power supply. For example, the potential of the supply roller 6d is DC−600V + AC1000V (peak-to-peak voltage) / 1 kHz. Here, the potential of the collection roller 6f is set to DC-0V, and the photosensitive drum 1a is set to the potential of the outer peripheral surface thereof to -600V by the charger 1b, and the laser beam is irradiated from the light traveling device 5. Thus, the potential of the portion where the electrostatic latent image is formed (image portion) is set to, for example, −50V.

  Here, the toner in the present embodiment is charged to, for example, a polyester negative charge. Between the developing roller 6c and the supply roller 6d, toner is supplied from the supply roller 6d to the development roller 6c due to the potential difference (supply potential difference) of the DC component between the first bias voltage application unit 10 and the second bias voltage application unit 11. An electric field in the moving direction is formed, and the fur brush 6e is provided between the supply roller 6d and the fur brush 6e by a potential difference (charging potential difference) of a DC component between the second bias voltage applying unit 11 and the third bias voltage applying unit 12. An electric field is formed in a direction in which the toner is pressed from the toner toward the supply roller 6d. In addition, an electric field is formed between the developing roller 6d and the collecting roller 6f in a direction in which the toner moves from the developing roller 6c toward the collecting roller 6f.

  As shown in FIG. 1, the developing unit 1 configured as described above has a photosensitive drum 1a facing the upper outer side from the second opening 1f on the outer peripheral side of the transfer belt 2a of the intermediate transfer member 2 described later in detail. It is arranged along the transfer belt 2a while contacting the outer peripheral surface. At this time, the developing units 1 that form toner images of magenta, yellow, cyan, and black are arranged in this order from the most upstream side with reference to the transfer direction (arrow direction) of the transfer belt 2a. Yes.

  The intermediate transfer body 2 is provided on the inner peripheral side of the transfer belt 2a, an endless transfer belt 2a that is circulated and moved by a driving roller 2b, a tension roller 2c, and support rollers 2d and 2e arranged on the inner peripheral side thereof. The plurality of primary transfer rollers 2f that press the transfer belt 2a against the outer peripheral surface of the photosensitive drum 1a of each developing unit 1 disposed on the outer peripheral side of the transfer belt 2a, and the transfer direction (arrow direction) of the transfer belt 2a It is provided so as to face the support roller 2e disposed on the downstream side in the transfer direction with respect to the developing unit 1 for forming a black toner image provided on the most downstream side of the transfer belt 2a and sandwich the transfer belt 2a with the support roller 2e. The secondary transfer roller 2g and the outer peripheral side of the transfer belt 2a on the upstream side in the transfer direction from the developing unit 1 that forms the magenta toner image provided on the most upstream side in the transfer direction. Vignetting, and a belt cleaning device 2h for removing toner attached to the transfer belt 2a.

  The recording medium conveying means 3 includes a plurality of conveying rollers 3b that rotate synchronously, conveys the recording medium S while taking it out of the cassette 3a, and between the secondary transfer roller 2g and the transfer belt 2a. It is for supply. Further, the recording medium S carrying the toner image by the secondary transfer roller 2g is conveyed to a fixing device 4 provided downstream in the recording medium S conveyance direction, which will be described later, and thereby the recording medium S on which the toner image is melted and fixed. Is further conveyed and discharged to the outside of the image forming apparatus main body B.

  The fixing device 4 includes a heating roller 4a and a pressure roller 4b that are provided so that their outer peripheral surfaces are in pressure contact with each other. The heating roller 4a is formed in a substantially columnar shape and is rotatable about a shaft. The heating roller 4a is configured by, for example, a heat-resistant elastic layer such as silicon rubber wound around a metal core, and includes a heat source such as a halogen lamp therein. It is supposed to be. On the other hand, the pressure roller 4b is formed in a substantially cylindrical shape capable of rotating the shaft, and is configured, for example, by winding a heat-resistant elastic layer such as silicon rubber around a metal core. Such a fixing device 4 presses the toner image carried by the recording material S fed between the heating roller 4a and the pressure roller 4b while heating and melting the recording material S, and applies the toner image to the recording material S. Can be melt-fixed.

  Next, the operation of the image forming apparatus A configured as described above will be described, and the operation and effect of the developing device 6 of this embodiment will be described.

  First, when the image forming apparatus A is operated, an image signal of the acquired recorded image is sent to a control unit (not shown), and an operation command is issued from the control unit to the developing unit 1. Upon receiving the command, the developing unit 1 uniformly charges the outer peripheral surface of the photosensitive drum 1a to a negative charge by the charger 1b, and the light traveling device 5 irradiates the laser beam to respond to the image signal of the recorded image. An electrostatic latent image is formed. At the time when the image forming apparatus A is operated, the developer agitating means 6g and 6h, the developing roller 6c, the supply roller 6d, and the collecting roller 6f (not shown) that are instructed by the control means are driven. The toner in the developing container 6a is agitated and the toner is supplied toward the outer peripheral surface of the supply roller 6d. At this time, since the outer peripheral surface of the supply roller 6d is solid and toner does not enter the toner roller, the toner contacts and adheres only to the outer peripheral surface of the supply roller 6d.

  Then, the supply roller 6d conveys the toner adhering to the outer peripheral surface thereof toward the fur brush 6e while rotating around the axis O3. At this time, since the fur brush 6e is in light contact with the outer peripheral surface of the supply roller 6d, the toner is frictionally contacted with an extremely small pressure when passing through the fur brush 6e, and is thereby charged with a negative charge. Further, since a bias voltage is applied to the supply roller 6d and the fur brush 6e, respectively, and an electric field is generated between the supply roller 6d and the fur brush 6e. Charge is applied and it is fully charged. Then, the sufficiently charged toner is electrically pressed to the supply roller 6d side and reliably carried on the outer peripheral surface of the supply roller 6d.

  The sufficiently charged toner is conveyed to a position facing the developing roller 6c by the rotation of the supply roller 6d, and is directed toward the outer peripheral surface of the developing roller 6c due to a potential difference between the developing roller 6c and the supply roller 6d. Fly and be supplied electrically. At this time, in this embodiment, since the toner is sufficiently charged by the fur brush 6e before being supplied to the developing roller 6c, it is not necessary to perform frictional charging at the time of supply, and the supply roller 6d and the developing roller 6c are not charged. Are arranged in a non-contact state, the toner is surely supplied and carried on the outer peripheral surface of the developing roller 6c. In addition, when the toner is electrically supplied to the developing roller 6c, the toner is supplied in a supply amount corresponding to the magnitude of the potential difference between the developing roller 6c and the supply roller 6d. . That is, a predetermined amount of toner is carried when it is supplied to the developing roller 6c.

  For this reason, in this embodiment, a restriction blade is provided for the toner carried on the developing roller 6c as in the conventional developing device, and the amount of toner adhered is regulated while applying pressure with the restriction blade to reduce the amount of toner. There is no need to form a layer, and since the toner is sufficiently charged before supply, there is no need to frictionally charge with this regulating blade. Therefore, in the developing device 6 of this embodiment, a leveling member 6i is provided instead of the regulating blade, and the leveling unevenness of the surface of the toner conveyed along with the rotation of the developing roller 6c is leveled by the leveling member 6i. It is supposed to be good.

  Next, the toner conveyed while being carried by the developing roller 6c and passing through the leveling member 6i is conveyed to a light contact portion with the photosensitive drum 1a. At this time, the toner is electrically supplied to the electrostatic latent image (image portion) of the photosensitive drum 1a exposed by the light traveling device 5 and having a relatively small absolute value of the potential, thereby forming a toner image. On the other hand, the toner is not supplied to the outer peripheral surface (non-image portion) of the photosensitive drum 1a other than the electrostatic latent image because the potential is DC-600 V, that is, the non-image portion corresponds to this non-image portion. The toner on the developing roller 6c remains carried on the developing roller 6c as it is. The remaining toner (residual toner) is conveyed to a light contact portion with the collecting roller 6f as the developing roller 6c rotates, and is electrically collected by an electric field formed between the developing roller 6c and the collecting roller 6f. It will be collected by being attached to 6f. Further, the residual toner adhering to the collection roller 6f is peeled off by the scraper 6j that makes a light contact with the rotation of the collection roller 6f, and collected in the developing container 6a. Incidentally, the collected toner is mixed with the toner in the developing container 6a by the pair of developer stirring means 6g and 6h, and is supplied again to the supply roller 6d for development.

  On the other hand, when a toner image is formed on each photosensitive drum 1a of each developing unit 1 provided for each color, the transfer belt 2a of the intermediate transfer body 2 drives the drive roller 2b that receives a command from the control means. As a result, it is transferred in the transfer direction. At this time, the transfer belt 2a is first pressed against the photosensitive drum 1a of the magenta developing unit 1 provided on the most upstream side in the transfer direction by the corresponding primary transfer roller 2f, and the magenta toner image is transferred. Transfer is started on the outer peripheral surface of the transfer belt 2a. Then, the transfer belt 2a is sequentially conveyed, and the toner images of the respective colors are superimposed on the toner image transferred by the developing unit 1 on the upstream side in the conveyance direction, that is, magenta, yellow, cyan, and black. The toner images are sequentially superimposed, and finally, a color toner image in which the toner images of all colors are superimposed on the outer peripheral surface of the transfer belt 2a is formed. Then, the recording medium conveying means 3 that has received an operation command from the control means conveys the recording medium S between the secondary transfer roller 2g and the transfer belt 2a, and a color toner image carried on the recording medium S by the transfer belt 2a is formed. Transcribed. The recording material S subjected to the secondary transfer is conveyed toward the fixing device 4 and passes between the heating roller 4a and the pressure roller 4b while applying heat and pressure, and the carried color toner image is melted. It will be fixed. Thus, the recording medium S on which the recording image is formed is further conveyed and discharged to the outside of the image forming apparatus main body B.

  Accordingly, in the developing device 6 of the present embodiment, an electrode member made of a conductive fur brush 6e is provided, the fur brush 6e is lightly contacted with the outer peripheral surface of the supply roller 6d, and toner is supplied from the fur brush 6e. Since the electric field is formed in the direction toward the roller 6d, the toner can be sufficiently charged before being supplied to the developing roller 6c. At the same time, the charged toner can be reliably carried on the supply roller 6d.

  At this time, since the outer peripheral surface of the supply roller 6d is densely formed and the toner does not enter the inside thereof, all of the toner adhering to the supply roller 6d can be arranged in the electric field, and the developing roller 6c Prior to supply to the toner, the toner can be sufficiently charged in advance.

  Since the toner can be sufficiently charged before being supplied to the developing roller 6c as described above, the developing roller 6c and the supplying roller 6d are brought into contact with each other while applying a large pressure as in the conventional developing device. It is considered unnecessary to triboelectrically charge by rubbing the toner at the time, and the collection roller 6f is separated from the supply roller 6d to electrically supply the toner to the development roller 6c and collect the toner from the development roller 6c. It becomes possible to do. Since the toner supply amount can be set to a predetermined amount according to the potential difference between the developing roller 6c and the supply roller 6d, it is not necessary to control the toner supply amount with a regulating blade to form a thin layer.

  Therefore, according to the developing device 6 of the present embodiment, the toner can be sufficiently charged without applying a large pressure to the toner as in the conventional developing device. It is possible to perform image formation over a long period of time.

  The embodiment of the developing device 6 according to the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and can be changed as appropriate without departing from the spirit of the present invention. For example, in the above embodiment, the potential of the developing roller 6c is set to DC-300V, the potential of the supply roller 6d is set to -600V as a direct current component, and the potential of the electrode member (fur brush) 6e is set to DC-1200V. However, an electric field is formed in the direction in which the toner moves from the supply roller 6d toward the developing roller 6c, and an electric field is formed in the direction in which the toner is pressed from the fur brush 6e toward the supply roller 6d. Thus, the potential of each member does not need to be limited. In this embodiment, the toner is charged to a negative charge. However, if the toner is a non-magnetic component, the present invention is applied to a developing device that performs development using toner charged to a positive charge. It may be done.

  Furthermore, in the present embodiment, the supply roller 6d is formed of conductive urethane rubber and the outer peripheral surface thereof is formed by being UV-processed and densely formed. However, the supply roller 6d is, for example, a sponge-like roller Further, the outer peripheral surface may be coated so that the toner does not enter the inside.

  In this embodiment, the developing roller 6c and the photosensitive drum 1a are lightly contacted, the developing roller 6c and the supply roller 6d are not contacted, and the developing roller 6c and the collection roller 6f are lightly contacted. However, each member is only required to be arranged so as not to apply a large pressure to the toner, and the developing roller 6c and the photosensitive drum 1a are not in contact with each other, or the developing roller 6c and the supply roller 6d. May be lightly contacted.

In addition to this, the fur brush 6e has a medium yarn electrical resistance of 10 ⁶ to 10 ¹⁰ Ωcm, a single yarn diameter of 10 to 40 μm, a hair length of 3 to 6 mm, and a planting density. Is formed so as to be 10,000 to 200,000 pieces / inch ² and is provided by being cut into 1 mm on the outer peripheral surface of the supply roller 6d. However, the configuration of the fur brush 6e is limited to the above. Instead, it is only necessary to have conductivity and be formed in a brush shape. For example, the amount of biting may be set smaller than 1 mm or conversely.

  Examples of the present invention will be specifically described below. However, the present invention is not limited to this example.

  In this embodiment, as shown in FIG. 2, the developing device 6 according to the present invention provided with a supply roller 6d made of a rubber roller having a dense outer peripheral surface and an electrode member 6e made of a fur brush, and a fur brush 20b on the outer peripheral surface. 3 provided with a supply roller 20a having a metal plate and an electrode member 20c made of a metal plate, a supply roller 30a made of a sponge roller having a porous outer peripheral surface, and a conductive sponge-like electrode. Using the developing device 30 shown in FIG. 4 provided with the member 30b, a performance comparison for charging the developer (toner) attached to the supply rollers 6d, 20a, and 30a of the developing devices 6, 20, and 30 is performed. The advantage of the developing device 6 according to the present invention will be clarified.

First, the used developing devices 6, 20, and 30 will be described.
FIG. 3 shows a developing device 20 including a supply roller 20a in which a fur brush 20b is implanted and an electrode member 20c made of a metal plate. In the developing device 20, the fur brush 20b of the supply roller 20a has a yarn resistance of the order of 10 ¹⁰ Ωcm, a single yarn diameter of 11 μm, a fiber length of 1.5 mm, and a planting density of 40,000 pieces / inch ² . It is formed so as to be implanted on the outer peripheral surface of the supply roller 20a. On the other hand, the electrode member 20c is an aluminum block, and a conductive rubber sheet is pasted on the surface thereof. The fur brush 20b of the supply roller 20a is cut into the electrode member 20c by 1 mm and lightly contacted. Yes. The other configurations such as the developing roller and the pair of developer stirring means of the developing device 20 are the same as those of the developing device 6 according to the present invention shown in FIG.

  FIG. 4 shows a developing device 30 including a sponge-like supply roller 30a and a sponge-like conductive electrode member 30b. In this developing device 30, the supply roller 30 a is a soft type special urethane foam (HPE-F manufactured by INOAC) having conductivity. The electrode member 30b is formed by attaching a conductive rubber sheet to the surface of a special urethane foam made of the same material as the supply roller 30a. The other configurations such as the developing roller and the pair of developer stirring means of the developing device 20 are the same as those of the developing device 6 according to the present invention shown in FIG.

  The developing device 6 according to the present invention is configured in the same manner as the developing device of the embodiment shown in FIG.

Next, a test method and an evaluation method will be described.
In this embodiment, the bias voltage applied to the supply roller and the electrode member is changed, and the charge amount of the toner adhering to the supply roller is measured using a suction type small charge amount measuring device (Model 210HS-2A manufactured by Trek). Then, the charging performance of the toner of each developing device is compared.

  That is, in each of the developing devices 6, 20, and 30, a DC bias voltage of −600 V to −1600 V is applied to the electrode members 6e, 20c, and 30b, and the potential of the DC component is set to −600 V to the supply rollers 6d, 20a, and 30a. While maintaining the AC component, a DC and AC superimposed bias voltage in which the AC component is changed to 0V, 500V, 1000V, 1500V (all between peak voltages) is applied, and supply rollers 6d, 20a, 30a and electrode members 6e, 20c, 30b are applied. The difference in the charge amount of the toner with respect to the potential difference (charging potential difference) of the DC voltage and the AC voltage is confirmed.

  In this embodiment, the test results obtained under the test conditions described above are 10 to 20 (−μC / g), preferably 15 to 20 when the toner used in this embodiment is sufficiently charged. Whether or not a charge amount of (−μC / g) can be obtained is confirmed, and the performance of charging the toner of each of the developing devices 6, 20, and 30 is evaluated.

Next, the test results are shown in FIGS.
FIG. 5 shows the results of a test conducted using the developing device 20 shown in FIG. 3, in which the AC voltage superimposed on the supply roller 20a and the charging potential difference between the supply roller 20a and the electrode member 20c are increased. However, it was confirmed that the charge amount of the toner was less than 10 (−μC / g). As a result, when the fur brush 20b is provided on the supply roller 20a, an electric field is formed between the tip of the fur brush 20b and the electrode member 20c, and the toner taken in between the conductive fibers of the fur brush 20b is absorbed. This is because it is not charged. Therefore, when the fur brush 20b is provided on the supply roller 20a, the toner cannot be sufficiently charged before being supplied to the developing roller 6c, and the supply roller 20a (fur brush 20b) is strongly applied to the developing roller 6c. It was confirmed that the toner had to be triboelectrically charged while applying mechanical pressure to the toner.

  FIG. 6 shows a result of a test performed using the developing device 30 shown in FIG. 3. Like the result of the developing device 20 shown in FIG. It was confirmed that even when the charging potential difference between the roller 30a and the electrode member 30b was increased, the charge amount of the toner was less than 10 (−μC / g). Also in this developing device 30, since the supply roller 30a is a sponge roller and the outer peripheral surface thereof is porous, it has been confirmed that the toner is taken into the supply roller 30a and is not sufficiently charged. . Therefore, it has been confirmed that in this developing device 30 as well, the supply roller 30a must be strongly pressed against the developing roller 6c to apply frictional charging while applying mechanical pressure.

  On the other hand, FIG. 7 shows the result of a test using the developing device 6 according to the present invention. From this result, the charge amount of the toner increases as the charging potential difference between the supply roller 6d and the fur brush 6e increases. It was confirmed that the toner charge amount can be increased to 10 to 20 (−μC / g) or more by controlling the charging potential difference. In addition, it was confirmed that the charge amount of the toner is dominant because the change in the charge potential difference, which is the difference between the DC components of the supply roller 6d and the fur brush 6e, has a greater effect than the voltage change of the AC component.

  From the above results, the developing device 6 according to the present invention can sufficiently charge the toner without applying a large pressure. At this time, the charging potential difference between the supply roller 6d and the electrode member 6e is controlled. As a result, it was proved that a charged charge can be suitably imparted to the toner.

1 is a diagram illustrating an image forming apparatus including a developing device according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a developing device according to an embodiment of the present invention provided in the image forming apparatus of FIG. 1. It is the figure which showed the image development apparatus provided with the supply roller in which the fur brush of the Example was formed. It is the figure which showed the developing device provided with the sponge-shaped supply roller of an Example. It is a figure which shows the test result performed using the image development apparatus of FIG. It is a figure which shows the test result performed using the image development apparatus of FIG. It is a figure which shows the test result performed using the image development apparatus of FIG.

Explanation of symbols

1 Developing section 1a Image carrier (photosensitive drum)
6 Developing Device 6a Developing Container 6b Opening 6c Developer Carrier (Developing Roller)
6d Supply member (supply roller)
6e Electrode member (fur brush)
6f Collection member (collection roller)
6g Developer stirring means (one developer stirring means)
6h Developer stirring means (the other developer stirring means)
6i Leveling member 6j Scraper 10 First bias voltage applying means 10a Power source 11 Second bias voltage applying means 11a Power source 12 Third bias voltage applying means 12a Power source A Image forming apparatus B Image forming apparatus main body

Claims (3)

A developer carrying member that is rotated around an axis while carrying a non-magnetic one-component developer on the outer peripheral surface, and the developer carried on the outer peripheral surface while rotating around an axis is supplied to the developer carrying member. And supplying the developer conveyed by the developer carrier to an image carrier on which an electrostatic latent image of a recorded image is formed, to visualize the electrostatic latent image Development apparatus of
A recovery member for recovering the developer remaining on the outer peripheral surface of the developer carrier after supplying the developer to the image carrier is a rotation direction of the developer carrier relative to the supply member An electrode member made of a conductive fur brush that is provided on the upstream side and is in contact with the outer peripheral surface of the supply member is provided, and at least the outer peripheral surface of the supply member is densely formed inside the electrode member. The developing device is configured such that the developer does not enter, and an electric field is formed between the supply member and the electrode member in a direction to press the developer against an outer peripheral surface of the supply member. . The developing device according to claim 1,
The supply member and the developer carrying member are arranged so as to be in non-contact or light contact, and the developer carried on the supply member is placed between the supply member and the developer carrying member. A developing device, wherein an electric field is formed in a direction to be moved toward the agent carrier. The developing device according to claim 1 or 2,
The collecting member and the developer carrying member are arranged so as to be in non-contact or light contact, and the developer on the outer peripheral surface of the developer carrying member is disposed between the developer carrying member and the collecting member. A developing device characterized in that an electric field is formed in a direction to move the toner toward the collecting member.

Images