JP2010210689A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus which can reduce the load of exchange for a latent image carrier coating film without enlarging the image forming apparatus in a configuration wrapping the latent image carrier coating film onto a surface of the latent image carrier more on the upstream side in the moving direction of the surface of the latent image carrier than a toner image forming position. <P>SOLUTION: A copying machine 500 has the coating film F configured in an endless loop state so that the coating film F which is the latent image carrier coating film that is separated from the surface of a photoreceptor 10 which is the latent image carrier can be wrapped around the surface of the photoreceptor 10 again. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a facsimile, and a printer.

Conventionally, an image forming apparatus using an electrophotographic method is widely known. This method is called the Carlson process, and the toner image is obtained on various transfer media such as plain paper by repeating the steps of charging, exposure, development, transfer, cleaning and initialization on the surface of the latent image carrier. . Then, the transferred toner image is heated and melted and fixed on the transfer medium to obtain a final image. Therefore, the cleaning process is indispensable in the Carlson process. As the cleaning process, there is known a process in which the transfer residual toner on the latent image carrier is removed by rubbing a cleaning member such as a cleaning blade or a cleaning brush against the surface of the latent image carrier.
In the configuration including such a cleaning member, there arises a problem that the surface of the latent image carrier is worn by sliding of the cleaning member and the life of the latent image carrier is reduced. In addition, when a latent image carrier made of an abrasion-resistant material is used in order to prevent the life of the latent image carrier from being reduced by rubbing the cleaning member, the latent image carrier has photoconductivity. However, a material having excellent wear resistance is used, which causes a problem that the material selection range of the latent image carrier is narrowed.

In recent years, image forming apparatuses equipped with a cleaner-less system that reuses toner that has been discarded in the cleaning process are also frequently seen. The feature of this cleanerless system is that unnecessary toner is collected in the development process by passing the surface of the latent image carrier on which the transfer residual toner exists after passing through the transfer position as it is through the charging / exposure process. Therefore, this method is sometimes called a simultaneous development cleaning method. As such a cleanerless type image forming apparatus, for example, there is an image forming apparatus described in Patent Document 1.
In an image forming apparatus equipped with this cleanerless system, the cleaning member is not completely eliminated but an alternative member is required. In other words, the toner remaining on the photoconductor after passing through the transfer process includes a relatively large amount of toner whose charge polarity is reversed and weakly charged toner. For this reason, the transfer residual toner is not necessarily a toner that can be suitably used as it is for the development process. Therefore, some conventional cleanerless type image forming apparatuses are equipped with a charging member for controlling the toner charging polarity for returning the charging polarity of the transfer residual toner to normal instead of the cleaning process. In such a cleaner-less method, charging is performed by a charging member for controlling the toner charging polarity separately from the charging necessary for forming a toner image on the latent image carrier, and therefore the surface of the latent image carrier is statically charged. There is a problem that the life of the latent image carrier is reduced due to the electric hazard. In addition, when a latent image carrier made of a material that is resistant to a hazard due to charging is used, there is a problem that the range of material selection for the latent image carrier is narrowed, as in the case of using the wear-resistant material described above. .
As described above, in the configuration in which the toner image is directly formed on the surface of the latent image carrier, there are problems that the life of the latent image carrier is reduced and the material selection range of the latent image carrier is narrowed.

  In the Japanese Patent Application No. 2008-238449 (hereinafter referred to as the prior application), the applicant of the present invention has proposed that the toner image on the latent image carrier is developed at least by development. A configuration is proposed in which a latent image carrier coating film is wound around the surface of the latent image carrier so that the surface of the latent image carrier is coated at a toner image forming position where the toner image is formed. In the configuration described in the prior application, the electrostatic latent image formed on the latent image carrier is developed through the latent image carrier coating film, and the latent image carrier coating film on which the toner image is formed is Before the next toner image is formed, it is separated from the surface of the latent image carrier. Therefore, it is possible to form an image without direct contact of the toner with the surface of the latent image carrier, and to improve the problems caused by the above-described configuration of directly forming the toner image on the surface of the latent image carrier. Can do.

  In the image forming apparatus described in the prior application, the latent image carrier covering film before being wound around the surface of the latent image carrier is accommodated in a roll shape, and the latent image carrier covering film wound around the surface of the latent image carrier Are discharged to the outside of the apparatus together with the recording medium, or collected by a collecting device arranged in the apparatus. That is, the structure is such that the latent image carrier-covered film separated from the surface of the latent image carrier after being wound on the surface of the latent image carrier is not wound again on the surface of the latent image carrier. For this reason, when there is no longer a roll of the latent image carrier-covered film before being wound around the surface of the latent image carrier, it is necessary to set a new roll of the latent image carrier-covered film in the image forming apparatus. Here, if the roll of the new latent image carrier-covered film set in the image forming apparatus is small, the latent image carrier-covered film roll frequently disappears, and the burden of maintenance increases. On the other hand, when the roll of the new latent image carrier-covered film is large, the space in the image forming apparatus for setting the roll of the new latent image carrier-covered film becomes large, leading to an increase in the size of the image forming apparatus.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a latent image carrier coating film on the surface of the latent image carrier upstream of the toner image forming position in the surface movement direction of the latent image carrier. An object of the present invention is to provide an image forming apparatus that can reduce the burden of replacing a latent image carrier-covered film with a winding configuration without increasing the size of the image forming apparatus.

In order to achieve the above object, a first aspect of the present invention provides a latent image carrier that moves on the surface, charging means that uniformly charges the surface of the latent image carrier, and an electrostatic latent image on the latent image carrier. An image forming apparatus comprising: a latent image forming unit that forms a toner image; and a toner image forming unit that supplies toner to an electrostatic latent image formed on the latent image carrier to form a toner image. The latent image carrier-covered film covers the surface of the latent image carrier at the toner image forming position where the toner image is formed by the toner image forming means. Before reaching the position where the surface of the latent image carrier coated with the latent image carrier covering film is again wrapped by the coating film winding means. The surface of the latent image carrier Coating film separating means for separating the latent image carrier-covered film that has passed through the toner image forming position in a covered state from the surface of the latent image carrier; and on the latent image carrier-coated film at the toner image forming position. Transfer means for transferring the formed toner image to a recording medium, and the latent image carrier coating film separated from the surface of the latent image carrier is wrapped around the surface of the latent image carrier again. The carrier-coated film is formed in an endless loop shape.
The invention according to claim 2 is the image forming apparatus according to claim 1, wherein the covering film winding means is arranged so that the latent image forming member is positioned more than the latent image forming position where the latent image is formed by the latent image forming means. Wrapping the latent image carrier covering film around the surface of the latent image carrier on the downstream side of the surface movement direction and upstream of the toner image forming position on the surface movement direction of the latent image carrier, Is a configuration in which the latent image carrier-covered film is separated from the surface of the latent image carrier on the upstream side in the surface movement direction of the latent image carrier from the uniform charging position uniformly charged by the charging means. It is characterized by this.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the transfer means forms a transfer nip between the latent image carrier and the latent image carrier with the latent image carrier coating film interposed therebetween. A latent image carrier-covered film and a recording medium respectively enter the transfer nip at the entrance side of the transfer nip, and the recording medium enters the latent image carrier via the latent image carrier-coated film at the transfer nip. The recording medium is separated from the latent image carrier-covered film that contacts and covers the surface of the latent image carrier on the exit side of the transfer nip, and then the latent image carrier from the surface of the latent image carrier. The body covering film is separated.
According to a fourth aspect of the present invention, in the image forming apparatus according to the first or second aspect, the transfer means forms a transfer nip between the latent image carrier covering film and the latent image carrier covering film. A latent image carrier-covered film and a recording medium respectively enter the transfer nip at the entrance side of the transfer nip, and the recording medium enters the latent image carrier via the latent image carrier-coated film at the transfer nip. The latent image carrier covering film is brought into contact with the recording nip and separated from the latent image carrier on the exit side of the transfer nip.
According to a fifth aspect of the present invention, in the image forming apparatus of the fourth aspect, the latent image carrier covering film that has passed through the transfer nip together with the recording medium heats and fixes the toner image on the recording medium. The image forming apparatus is characterized in that it enters the fixing section together with the recording medium, and is separated from the recording medium after passing through the fixing section.
According to a sixth aspect of the present invention, in the image forming apparatus according to the fifth aspect, the fixing device includes a heating roller having a heat source therein, and a pressure roller that contacts and pressurizes the heating roller. A fixing nip as the fixing portion is formed at a contact portion between the roller and the pressure roller.
According to a seventh aspect of the present invention, in the image forming apparatus according to the fifth aspect, the fixing device faces the latent image carrier covering film at the fixing portion and is orthogonal to the moving direction of the latent image carrier covering film. It comprises a plate-like heating body extending in the direction to do.
The invention according to claim 8 is the image forming apparatus according to any one of claims 5 to 7, wherein the latent image carrier-covered film is downstream of the fixing unit in the moving direction and the latent image. It has a film cooling means for cooling the latent image carrier covering film on the upstream side of the position where the carrier covering film is separated from the recording medium.
According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first to eighth aspects, after the latent image carrier-covered film is separated from the surface of the latent image carrier, the latent image is again formed. A film cleaning means is provided for removing foreign matter on the surface of the latent image carrier-covered film until it is wound around the surface of the carrier.
The invention according to claim 10 is the image forming apparatus according to any one of claims 1 to 9, wherein the latent image carrier covering film is separated from the surface of the latent image carrier and then the latent image is again formed. It is characterized by comprising a polarity control means for aligning the charging polarity of the toner existing on the surface of the latent image carrier covering film until it is wound around the surface of the carrier with a predetermined charging polarity.
According to an eleventh aspect of the present invention, in the image forming apparatus according to the tenth aspect, the polarity control means includes a brush roller-shaped polarity control brush to which a voltage having the same polarity as the toner used in toner image formation is applied. It is a feature.
According to a twelfth aspect of the present invention, in the image forming apparatus of the tenth aspect, the charging unit includes a roller-shaped charging roller, and the polarity control unit is applied with a voltage having the same polarity as the toner used in toner image formation. The charging roller and the polarity control roller are a common roller member.
The invention according to claim 13 is the image forming apparatus according to claim 10 or 12, wherein the polarity control unit is configured to align the charging polarity of the toner existing on the surface of the latent image carrier covering film with a predetermined charging polarity. In addition, the toner on the film collects the toner having a predetermined charging polarity on the downstream side in the moving direction of the latent image carrier-covered film and on the upstream side in the moving direction of the latent image carrier-covered film from the toner image forming position. A collection means is provided.
According to a fourteenth aspect of the present invention, in the image forming apparatus according to the thirteenth aspect, the on-film toner collecting means is configured to carry the latent image carrier on the upstream side in the surface movement direction of the latent image carrier relative to the toner image forming position. A rotatable sleeve member disposed in the developing device as the toner image forming means so as to face the latent image carrier coated with the body covering film, and a plurality of magnetic poles disposed in the sleeve member. And a voltage applying means for applying a voltage having a polarity opposite to the predetermined charging polarity to the sleeve member.
The invention according to claim 15 is the image forming apparatus according to claim 14, wherein the sleeve member moves in the direction of surface movement of the sleeve member at a position facing the latent image carrier covered with the latent image carrier coating film. However, the sleeve member rotates so as to be opposite to the surface moving direction of the latent image carrier-covered film.

  According to the present invention, since the latent image carrier-covered film is configured in an endless loop shape, the latent image carrier is configured like a configuration in which a roll-shaped latent image carrier-coated film is wound on the surface of the latent image carrier. Since the latent image carrier-covered film wound on the surface is not lost, there is an excellent effect that the burden of replacing the latent image carrier-covered film can be reduced without increasing the size of the image forming apparatus.

1 is a schematic configuration diagram of an entire copying machine according to a first embodiment. FIG. 2 is an enlarged explanatory view of an image forming unit of the copier according to the first embodiment. FIG. 3 is an explanatory diagram of a state in which the covering film and the sheet face each other at the transfer position of the image forming unit of the copying machine according to the first embodiment. FIG. 3 is an enlarged explanatory diagram of an image forming unit of a copying machine according to a second embodiment. FIG. 6 is an explanatory diagram illustrating an example of a bias applied to a toner collecting roller provided in the copier according to the second embodiment. FIG. 6 is an explanatory diagram illustrating an example of bias applied to a developing roller provided in the copier according to the second embodiment. FIG. 9 is a schematic configuration diagram of an entire copying machine according to a third embodiment. FIG. 6 is an explanatory diagram of a state in which a covering film and a sheet face each other at a transfer position of an image forming unit of a copying machine according to a third embodiment. FIG. 5 is an enlarged explanatory view of a heat fixing device provided in the copier of Embodiment 3. FIG. 6 is an enlarged explanatory view of a heat fixing device provided in a copying machine according to a fourth embodiment. FIG. 6 is an enlarged explanatory view of a heat fixing apparatus including a cooling unit to which the copying machine of the fourth embodiment can be applied.

[Embodiment 1]
Hereinafter, a first embodiment (hereinafter referred to as a first embodiment) in which the present invention is applied to an image forming apparatus will be described with reference to the drawings. The embodiments of the present invention are not limited to those described below, and various modifications can be made without departing from the spirit of the present invention.

FIG. 1 is a schematic configuration diagram of an entire copying machine (hereinafter referred to as a copying machine 500) as an image forming apparatus according to the first embodiment.
In the copying machine 500, a copying machine main body 100 for forming an image is placed on a sheet bank 300 as a paper feeding device, and an image reading device 200 is attached to the upper part of the copying machine main body 100. An automatic document feeder 400 that can be opened and closed up and down with the back side as a fulcrum is mounted on the image reading apparatus 200.

The copying machine main body 100 is provided with a drum-shaped photoreceptor 10 as an image carrier inside.
FIG. 2 is an enlarged explanatory view of the image forming unit that is in the vicinity of the photoconductor 10 of the copying machine main body 100 of the first embodiment. FIG. 3 is a coating film F at the transfer position B of the image forming unit shown in FIG. It is explanatory drawing of the state to which sheet | seat S and oppose.
A charging device including a charging roller 8 is disposed around the photoconductor 10 on the left side of the photoconductor 10. Around the photosensitive member 10, the charging roller 8, the developing device 12, and the transfer device 13 are sequentially arranged from the upstream side of the surface moving direction with respect to the surface moving direction (counterclockwise direction) of the photosensitive member 10 indicated by an arrow A in the drawing. ing. Note that the copying machine 500 is not provided with a cleaning device for cleaning the photoreceptor 10.
In the developing device 12, by using the developing roller 4, a toner is attached to a coating film F, which will be described in detail later, and the electrostatic latent image on the photoconductor 10 is visualized.

In addition, the transfer device 13 is configured by a transfer belt 17 being stretched between a first stretching roller 15 and a second stretching roller 16 that are arranged above and below, and at the transfer position B, the circumference of the photoreceptor 10. Pressed against the surface and brought into contact. At the transfer position B, the transfer roller 7 facing the photoconductor 10 with the transfer belt 17 interposed therebetween is disposed, and the transfer belt 17 forms a coating film F to be described later by a transfer nip formed by the photoconductor 10 and the transfer roller 7. It is in contact with the photoconductor 10 with being sandwiched.
In the copying machine main body 100, a coating film transport that transports a coating film F that is a “latent image carrier coating film” that covers the surface of the photoreceptor 10 at a development position where the developing roller 4 faces the surface of the photoreceptor 10. A device 20 is arranged. The covering film conveying device 20 includes a loop-shaped covering film F, a first film stretching roller 201, a second film stretching roller 202, a third film stretching roller 203, and a fourth film stretching roller 204. Then, the coating film F is moved endlessly in accordance with the movement of the surface of the photoreceptor 10. In the coated film conveying apparatus 20 according to the first embodiment, the first film stretching roller 201 is a driving roller, and the first film stretching roller 201 is driven to rotate by driving a driving source (not shown). Move F endlessly.

The covering film F transported by the covering film transporting device 20 is wound so as to be in close contact with the surface of the photoreceptor 10 through the surface of the winding roller 81 and covers the surface of the photoreceptor 10. That is, in the first embodiment, the position where the winding roller 81 and the photoconductor 10 face each other is the latent image carrier covering film winding position. The coating film F sticks to the photoconductor 10 by the pressing force of the winding roller 81 and is conveyed downstream as it is, and passes through the development position and the transfer position B with the surface of the photoconductor 10 covered.
The photoreceptor 10, the charging roller 8, and the laser writing device 47 are disposed inside the loop of the covering film F, and the developing device 12 and the transfer device 13 are disposed outside the loop of the covering film F. The developing roller 4 of the developing device 12 and the transfer belt 17 of the transfer device 13 are in contact with the coating film F.

  Further, inside the copying machine main body 100, a sheet S, which is a recording medium fed from a sheet cassette 61 (described later) in the sheet bank 300, is conveyed from the lower side to the upper side through the transfer position B to the stack position. A transport device C is provided. The sheet conveying apparatus C forms a supply path R1, a manual feed path R2, and a sheet conveyance path R.

  In the sheet conveyance path R, the registration roller 21 is disposed at a position upstream of the photosensitive member 10 in the conveyance direction of the sheet S. Further, a thermal fixing device 22 is disposed at a position downstream of the photosensitive member 10 in the transport direction. The thermal fixing device 22 includes a heating roller 30 as a heating member having a heat source therein and a pressure roller 32 as a pressure member.

  Further, a discharge roller 35 is disposed further downstream in the conveyance direction of the heat fixing device 22, and a discharge stack unit 39 for stacking sheets on which images have been formed is further provided.

  As described above, the laser writing device 47 is provided inside the loop of the covering film F. The laser writing device 47 includes a laser light source (not shown), a scanning rotary polygon mirror 48, a polygon motor 49, a scanning optical system 50 such as an fθ lens, and the like.

  The image reading apparatus 200 includes a light source 53, a plurality of mirrors 54, an imaging optical lens 55, an image sensor 56 such as a CCD, and the like. A contact glass 57 is provided on the upper surface.

  The automatic document feeder 400 on the contact glass 57 is provided with a document setting table (not shown) at the document placement position and a document stack table (not shown) at the discharge position. In addition, a sheet conveyance device having a document conveyance path (not shown) that conveys a document sheet from a document setting table to a document stacking table through a reading position on the contact glass 57 of the image reading device 200 is provided. The sheet conveying apparatus includes a plurality of sheet conveying rollers (not shown) that convey the original sheet.

  The sheet bank 300 includes therein a plurality of sheet cassettes 61 for storing sheets S such as transfer paper and OHP film as recording media. Each sheet cassette 61 includes a calling roller 62, a supply roller 63, and a separation roller 64, respectively. A supply path R1 leading to the sheet conveyance path R of the copying machine main body 100 is formed on the right side of the multi-stage sheet cassette 61 in the drawing. The supply path R <b> 1 is also provided with a plurality of sheet transport rollers 66 that apply a transport force to the sheet S by rotating and transport the sheet S.

  A manual paper feed unit 68 is provided on the right side of the copying machine main body 100 in the drawing. The manual feed unit 68 includes a manual feed path R <b> 2 that opens and closes a manual feed tray 67 and guides a manually fed sheet S set on the manual feed tray 67 to the sheet conveyance path R. Similarly, the manual feed tray 67 is provided with a calling roller 62, a supply roller 63, and a separation roller 64.

  When copying using the copying machine 500 having such a configuration, first, a main switch (not shown) is turned on, and a document is set on a document setting table of the automatic document feeder 400. In the case of a book document, the automatic document feeder 400 is opened, the document is set directly on the contact glass 57 of the image reading device 200, and the automatic document feeder 400 is closed to press the document.

  When a start switch (not shown) is pressed, when an original is set on the automatic document feeder 400, the image reading device 200 is driven after the document is moved by the sheet carrying roller through the document carrying path onto the contact glass 57. Then, the document contents are read and discharged onto the document stacking table. On the other hand, when the document is set directly on the contact glass 57, the image reading apparatus 200 is immediately driven to read the content of the document.

  When the image reading apparatus 200 is driven, the image reading apparatus 200 moves the light source 53 along the contact glass 57, reflects light from the light source 53 on the document surface on the contact glass 57, and reflects the reflected light into a plurality of light. The light is reflected by a mirror 54, passes through an imaging optical lens 55, is put in an image sensor 56, and the image content is read by the image sensor 56.

  At the same time, as the electrostatic latent image forming step, the photosensitive member 10 is rotated by a photosensitive member driving motor (not shown), and the surface of the photosensitive member 10 is uniformly charged by the charging device including the charging roller 8. Next, the writing process is performed by irradiating the writing light 3 from the laser writing device 47 according to the content of the original read by the image reading device 200. Next, the coating film F conveyed by the coating film conveyance device 20 is wound around the surface of the photosensitive member 10 at the facing portion between the photosensitive member 10 and the winding roller 81, and the surface of the photosensitive member 10 is covered with the coating film F. To do. Thereafter, a toner is attached to the coating film F that covers the surface of the photoreceptor 10 using the developing device 12 according to the latent image formed on the photoreceptor 10 under the coating film F, and the electrostatic latent image Visualization (development) is performed.

On the other hand, at the same time as the start switch is pressed, the sheet S is sent out by the calling roller 62 from within the sheet cassette 61 containing the sheet S of the selected size among the multi-stage sheet cassettes 61 in the sheet bank 300. The sheet S sent out by the calling roller 62 is separated and conveyed one by one by a supply roller 63 and a separation roller 64 following the calling roller 62, and is sent to the supply path R1. The sheet S sent to the supply path R1 is transported by the sheet transport roller 66 and guided to the sheet transport path R, and is abutted against the registration roller 21 and stopped. Then, the registration roller 21 rotates so that the timing at which the toner image visualized on the coating film F on the surface of the photoconductor 10 reaches the transfer position B of the sheet S coincides, and the sheet S is moved to the photoconductor 10. It is sent to the right side of.
When an image is formed on the manual sheet S set on the manual feed tray 67, the manual sheet S set on the manual feed tray 67 of the manual sheet feeder 68 is sent to the manual supply path R2. Then, as in the case where image formation is performed on the sheet S in the sheet cassette 61 described above, the manual sheet S is fed to the right side of the photoconductor 10 in synchronization with the rotation of the photoconductor 10 by the registration roller 21. .

  The sheet S fed to the right side of the photoconductor 10 covers the surface of the photoconductor 10 at the transfer position B, and overlaps with the coating film F on which the toner image is formed. In the copying machine 500 of the first embodiment, a transfer bias is applied to the transfer roller 7 by a bias applying device (not shown), and a transfer electric field is formed between the transfer roller B and the photoconductor 10. Therefore, as shown in FIG. 3, the toner image facing the sheet S at the transfer position B moves from the surface of the covering film F covering the photoreceptor 10 to the sheet S by the transfer electric field, and the toner image is moved to the covering film. Transferred from the surface of F to the surface of the sheet S. The sheet S on which the toner image has been transferred is separated from the photoconductor 10 covered with the covering film F and conveyed to the heat fixing device 22.

In the copying machine 500 according to the first embodiment, the covering film F is stretched between the surface of the photoreceptor 10 on the downstream side of the transfer position B in the surface movement direction and the third film stretching roller 203. For this reason, the covering film F is pulled in the direction of the third film stretching roller 203 arranged in a direction different from the conveying direction of the sheet S, and is separated from the sheet S along the surface of the photosensitive member 10. It is also separated from the surface of the body 10. In the copying machine 500 according to the first embodiment, the configuration in which the covering film F is stretched between the third film stretching roller 203 and the photoreceptor 10 functions as a latent image carrier covering film separating unit.
The surface of the photoconductor 10 that has passed the transfer position B and from which the coating film F has been separated is removed from the residual potential by a neutralizing device (not shown), and is ready for the next image formation starting from the charging roller 8 described above.

On the other hand, the sheet S on which the toner image has been transferred and conveyed to the thermal fixing device 22 is passed through a fixing nip as a fixing portion formed by the heating roller 30 and the pressure roller 32 and conveyed to these rollers. At the same time, heat and pressure are applied to fix the toner image to the sheet S.
Thereafter, the sheet S on which the toner image is fixed passes through the discharge roller 35 and is discharged and stacked on the discharge stack portion 39.
The copying machine 500 according to the first exemplary embodiment is a monochrome image forming apparatus that includes one photosensitive member and one developing device. However, a full-color image forming device in which four developing devices are arranged on one photosensitive member. Even so, a configuration in which the latent image carrier covering film is wound around the surface of the photosensitive member is applicable.

As the covering film F, a film of a transparent, lightweight and flexible film-like material having a thickness of about 10 [μm] for wrapping foods and dishes generally used as a food wrap film can be used. . These films are rich in heat resistance and water resistance, and are said to be adaptable to temperatures from minus 60 [deg.] C. to around 150 [deg.] C. Wrap film materials include cellophane, polyethylene terephthalate (PET), stretched polypropylene (OPP), nylon (NY), polyethylene (PE), polypropylene (PP), polyvinylidene chloride (PVDC), polyvinyl alcohol (PVA), polychlorinated. Examples include vinyl (PVC) and polymethylpentene (PMP). Further, polyethylene + polypropylene (PE + PP), nylon + polyethylene (NY + PE), and the like can be used as a wrap film made of a composite material.
As the covering film F that can be used in the first embodiment, it can hold static electricity, can withstand a certain amount of stress, can maintain a film state even when pulled, and can maintain a film state without being dissolved in water to some extent. The characteristics such as are also required. Needless to say, the coating film F used in Embodiment 1 is not limited to the food wrap film described above as long as it has these characteristics.

  The covering film F of Embodiment 1 is a seamless loop member. For example, a product manufactured as follows can be used. The resin material of the coating film F described above is put into a rotating cylindrical mold in a fluidized state. A resin layer having a longer dimension than that at the time of use is formed by centrifugal molding, and solvent evaporation or reaction solidification is performed. In this method, the resin layer is peeled from the mold and the opening of the resin layer is cut. Here, when the coating film F manufactured in a loop shape has an air surface on the inside and a mold surface on the outside, the toner image is created by the copying machine 500 on the mold surface. However, the loop-shaped covering film F is not limited to this, and a covering film F having a seam may be used.

Next, the conveying operation of the coating film F after transferring the toner image will be described.
In the copying machine main body 100 according to the first exemplary embodiment, the latent image carrier in which the covering film F is wound around the photosensitive member 10 again at the downstream side of the moving direction of the covering film F from the position where the covering film F is separated from the photosensitive member 10. A development recovery auxiliary brush 23 serving as a polarity control means is arranged at a position upstream of the coating film winding position in the movement direction of the coating film F. The development recovery auxiliary brush 23 is a brush roller to which a negative polarity bias having the same polarity as the toner contained in the developer in the developing device 12 is applied by a bias application unit (not shown).

After the toner image is transferred to the sheet S, the coating film F is separated from the photoconductor 10 and passes through the third film stretching roller 203 and the fourth film stretching roller 204, and then the development recovery assist brush 23. To reach the position opposite. Here, the transfer residual toner remaining on the coating film F is given a negative charge, and the charge polarity of the transfer residual toner is aligned on the negative polarity side.
On the other hand, the surface of the photoconductor 10 after the covering film F is separated is removed from the residual potential by a neutralizing device (not shown), charged by the charging roller 8, and subsequently, an electrostatic latent image is formed by the laser writing device 47. Applied. The covering film F in which the charging polarity of the transfer residual toner on the surface is aligned on the negative polarity side passes through the first film stretching roller 201 and the second film stretching roller 202 and is stretched by the winding roller 81. Reach the position. Here, the covering film F is again wound around the surface of the photoreceptor 10 on which the charge removal, charging, and electrostatic latent image have been formed, by the winding roller 81, and the covering film F is conveyed to the developing position. At the developing position, the transfer residual toner having the negative polarity on the coating film F and the charged polarity aligned is mixed with the developer on the developing roller 4 and contributes again to the development together with the toner that has entered the developing device 12.
The covering film F that has passed the development position is conveyed to the transfer position B, overlapped with the sheet S as described above, and the toner image is transferred to the sheet S. Image formation is continued by repeating this process.

  In the first embodiment, the transfer residual toner on the surface of the coating film F after passing through the transfer position B is configured to have the charging polarity aligned by the polarity control means and collected by the developing device 12. As a configuration for removing the transfer residual toner on the surface, a configuration including a cleaning unit for cleaning the toner by mechanical rubbing such as a blade or a brush may be used.

  In the first embodiment, the development recovery auxiliary brush 23 made of a brush roller is used as the polarity control means, but the member used as the polarity control means is not limited to the brush roller, and a roller member may be used. When a roller member is used as the polarity control means, the same roller member as the charging roller 8 can be used so that parts can be shared by the two members, and the manufacturing cost can be reduced.

  In the copying machine 500 according to the first exemplary embodiment, the surface of the photoconductor 10 is moved between the developing position where the developing roller 4 of the developing device 12 and the surface of the photoconductor 10 are opposed to the transfer position B in the moving direction of the photoconductor 10. The coating film F covers the surface. Then, after passing through the transfer position B, the coating film F is separated from the surface of the photoconductor 10, and the photoconductor before development by the winding roller 81 disposed on the upstream side of the development position in the surface movement direction of the photoconductor 10. The coating film F is wound around the surface of 10. With such a configuration, in the copying machine 500, the toner image is formed on the coating film F that covers the photoreceptor 10, and the toner does not directly adhere to the surface of the photoreceptor 10. For this reason, a photoconductor cleaning means for cleaning the surface of the photoconductor 10 is unnecessary.

  As an example of a conventional image forming apparatus that does not require a photosensitive member cleaning unit, Patent Document 1 discloses a cleaner-less system that collects unnecessary toner in a development process, and increases the charging efficiency of transfer residual toner, thereby efficiently using fog toner. A cleanerless type image forming apparatus that can be removed to improve image forming quality is disclosed. In this apparatus, a charging roller, a developing device, a primary transfer roller, and a charging auxiliary means (charging brush) are arranged around the photosensitive drum. The developing device performs negative development simultaneous cleaning by moving the negatively charged toner from the rotating sleeve to the toner image forming region while moving the toner from the non-forming region to the rotating sleeve. By placing a charging brush charging auxiliary means (charging brush) downstream of the primary transfer roller and applying -1000 [V], the transfer residual toner on the photosensitive drum is negatively charged. In the primary transfer from the photosensitive drum to the intermediate transfer belt, a primary transfer bias voltage of 700 [V] higher than 500 [V] applied in the toner image forming area is primary transferred in the inter-paper space where the toner image is not formed. This is to prevent defects in the residual toner by applying to the roller.

In an image forming apparatus equipped with an electrophotographic cleanerless system, the cleaning member is not completely eliminated but an alternative member is required.
The reason for this is that “transfer residual toner remains on the image carrier against the transfer bias voltage of the transfer device that draws the toner charged to the normal charging polarity to the recording material or the intermediate transfer belt. Most of the toner is insufficiently charged or charged to a polarity opposite to the normal charging polarity, and like toner charged to the normal charging polarity, it is not collected on the developing member by dynamic development. '' “Especially when the image formation with a high image ratio is performed continuously and the toner is replenished in a high-temperature and high-humidity environment or at the endurance, the ratio of the toner that is insufficiently charged increases, so that the image is formed as a so-called fog toner. A large amount of toner adheres to the carrier because the charge in the developing device is low and the environment is such that the charge application is severe. Therefore, the image forming quality is deteriorated by hindering normal charging and exposure of the image bearing member.Therefore, in the cleanerless type image forming apparatus, an auxiliary charging means is arranged on the downstream side of the transfer apparatus, and the transfer residual which is insufficiently charged. The toner or the transfer residual toner charged to the opposite polarity is charged to the normal charge polarity. That is, even though the cleanerless system is used, a member that substitutes the function of the cleaning member is required.

In addition, in the configuration in which the charging auxiliary means is provided on the downstream side of the transfer device as in Patent Document 1, an electrostatic hazard is applied to the surface of the latent image carrier separately from the charging and exposure necessary for forming the toner image. The life of the latent image carrier is likely to be shortened due to a change in photoconductivity on the surface of the latent image carrier due to electrostatic hazards, as compared with a configuration without auxiliary means.
The copier 500 according to the first exemplary embodiment includes a development recovery auxiliary brush 23 that charges the transfer residual toner to a normal charging polarity as in the conventional charging auxiliary unit. However, since the target subject to electrostatic hazard by the development recovery auxiliary brush 23 is the coating film F, unlike the latent image carrier on which the electrostatic latent image is formed, the influence of the electrostatic hazard is small. Further, in the copying machine 500 of the first embodiment, the photoreceptor 10 is inside the loop of the covering film F, and the circumference of the covering film F is longer than the circumference of the photoreceptor 10. For this reason, when one place on the peripheral surface of the covering film F is affected by the electrostatic hazard due to charging of the development recovery auxiliary brush 23, one place on the peripheral surface of the latent image carrier having the conventional configuration is charged auxiliary. Significantly less than the opportunity to be affected by electrostatic hazards due to the charging of the means.
Even if a member that replaces the function of the cleaning member is provided, there is a limit in removing the toner directly attached to the surface of the photoreceptor once.

As another example of a conventional image forming apparatus that does not require a photoconductor cleaning means, for example, Japanese Utility Model Laid-Open No. 03-065146 discloses an apparatus that obtains an image by feeding a sheet film and superimposing it on another transfer medium. Yes. This apparatus obtains a latent image by exposing a film sheet of microcapsule paper, which is a photosensitive pressure sensitive paper, and then superimposes it on developer paper, which is a recording paper, to obtain an image. Then, by passing both of them through a pressure developing device, the microcapsules of the microcapsule paper are destroyed, so that the dye precursor of the unexposed part is applied to the surface of the developer paper as the recording paper It reacts with and develops color. Next, the device is such that a final image is obtained by promoting color development by a heat fixing device.
The apparatus described in this publication has an example of an apparatus that obtains an image by superimposing a sheet and a recording paper, but this does not use an electrophotographic method, and there is no problem of cleaning when toner remains. The image forming apparatus is essentially different from the copier 500 of the first embodiment.

  On the other hand, in the copying machine 500 according to the first embodiment, the electrostatic latent image on the photoconductor 10 that is an electrophotographic photoconductor is developed through the coating film F that is a film layer, and then this toner image is transferred to the sheet S. Then, by repeating the step of separating the coating film F from the photoconductor 10, it is possible to essentially prevent the toner from remaining on the photoconductor 10. For this reason, a cleaning means for cleaning the photoreceptor 10 is unnecessary. For this reason, since the electrical influence does not increase while avoiding the influence of mechanical wear on the photoreceptor 10, the durability of the photoreceptor 10 is remarkably improved.

Next, the developing device 12 that forms a toner image corresponding to the electrostatic latent image formed on the surface of the photoreceptor 10 on the coating film F will be described.
The developing device 12 provided in the copying machine 500 is a two-component developing device composed of a magnetic carrier and toner. The copying machine 500 includes a toner bottle (not shown) that stores toner used in the developing device 12, and the toner in the toner bottle is supplied to the developing device 12 by a toner replenishing device (not shown).
The toner supplied from a toner supply port (not shown) by the toner supply device is supplied onto a developer composed of a magnetic carrier and toner in a developing container 12a which is a casing of the developing device 12. The supplied toner is transported in the depth direction of the paper surface in FIG. 2 while being agitated by the spiral second transport screw 2 together with the developer. The conveyance path provided with the second conveyance screw 2 and the conveyance path provided with the first conveyance screw 1 are communicated with each other at the rear end in the paper plane direction and the front end in the paper plane in FIG. Then, the developer that has reached the end in the paper surface in FIG. 2 by the second transport screw 2 moves to the transport path where the first transport screw 1 is arranged, and the first transport screw 1 causes the paper surface in FIG. It is conveyed from the back to the front. Then, the developer that has reached the front end in FIG. 2 by the first transport screw 1 moves to the transport path in which the second transport screw 2 is arranged. As described above, the developer circulates in the developing device 12.
The developer in which the supplied toner is agitated is pumped up to the surface of the developing roller 4 by the magnetic force of the developing roller 4 having a magnet built therein in the conveying path conveyed by the first conveying screw 1. As indicated by an arrow D in the figure, the developer adsorbed by the magnetic force on the surface of the developing roller 4 rotating in the clockwise direction in the figure is regulated to a fixed amount by the developing doctor 70 and the toner and the magnetic carrier are rubbed together. Charged.

The developer composed of the charged magnetic carrier and toner rises at the main pole of the maximum magnetic strength of the developing roller 4 and comes into contact with the coating film F that covers the surface of the photoreceptor 10. A bias voltage is applied to the developing roller 4, and toner is selectively attached to the surface of the coating film F by the electrostatic latent image on the photoreceptor 10 and developed. The toner density of the developer in the developing container 12a is monitored by the toner density sensor 5. When the toner concentration is low, a toner replenishing device (not shown) is driven to supply toner from a toner bottle (not shown) and control is performed so as to keep the toner concentration constant.
Further, a reference pattern is formed with toner on the covering film F covering the surface of the photoreceptor 10, and the pattern density sensor 6 measures the reflection density of the reference pattern. Based on the measurement result of the pattern density sensor 6, the output value of the toner density sensor 5 is automatically selected as to which toner replenishment operation should be started.

  As shown in FIG. 2, the toner concentration sensor 5 is installed under the second conveying screw 2 that conveys the developer, and measures the toner concentration of the developer from the magnetic permeability of the developer. When the toner concentration is lowered, the magnetic carrier is concentrated, so that the magnetic permeability is increased. If the value of the magnetic permeability detected by the toner concentration sensor 5 exceeds a predetermined value (threshold value), it is determined that the toner concentration has become low, and the control unit (not shown) transfers to the toner supply device until the predetermined toner concentration is reached. A signal for toner supply operation is sent.

  By such replenishment control, the density of the reference pattern formed on the covering film F covering the surface of the photoconductor 10 is controlled to be constant, but when the toner in the toner bottle runs out, It is determined from the outputs of both the pattern density sensor 6 and the toner density sensor 5 that detect the density of the reference pattern using a determination mechanism (not shown) that the toner has run out.

  In Embodiment 1, toner is supplied from a toner bottle. The toner used in the copying machine 500 can be preferably a toner containing a polyester resin, but is not limited thereto.

Next, toner used in the copying machine 500 will be described.
The polyester of the toner containing the polyester resin is a diacid compound having a polyhydric alcohol and a polyacid (mostly a compound having a diol group and a diacid (— (COOH) ₂ ) or a diester (— (COOR) ₂ )). Alternatively, an unmodified polyester resin is used in which a polyester compound (unmodified polyester) is obtained by dehydration (or dealcoholization) condensation reaction with a diester compound. Further, a polyisocyanate compound obtained by a condensation reaction of diisocyanate (a compound having two —NCO groups) and an active hydrogen compound (particularly a diol, a dioic acid, or a compound having both OH and COOH groups) It may contain a modified polyester resin.

  The ratio of the polyvalent isocyanate compound is usually 5/1 to 1/1, preferably 4/1, as an equivalent ratio [NCO] / [OH] of the isocyanate group [NCO] and the hydroxyl group [OH] of the polyester having a hydroxyl group. To 1.2 / 1, more preferably 2.5 / 1 to 1.5 / 1.

  By using the unmodified polyester and the urea-modified polyester in combination, the low-temperature fixability and the glossiness when used in a full-color image forming apparatus are improved. Therefore, it is preferable to use the urea-modified polyester alone. The unmodified polyester may include a polyester modified with a chemical bond other than a urea bond.

The unmodified polyester and the urea-modified polyester are preferably at least partially compatible with each other in terms of low-temperature fixability and hot offset resistance. Therefore, it is preferable that the unmodified polyester and the urea-modified polyester have a similar composition.
The weight ratio of unmodified polyester to urea-modified polyester is usually about 20/80 to 95/5.
The urea-modified polyester used as the prepolymer may contain a urethane bond as well as a urea bond. The molar ratio of urea bond content to urethane bond content is usually 100/0 to 10/90.

  In the copying machine 500 of the first embodiment, toner having a melting point of about 120 [° C.] is used, the fixing temperature is set to 150 [° C.], and the coating film F that can be adapted to 150 [° C.] or higher is used.

Next, an experiment for confirming that development can be performed in a state where the surface of the photoreceptor is covered with the latent image carrier covering film will be described.
[Experiment 1]
As Experiment 1, the following experiment was performed using an image MP5000 (manufactured by Ricoh) as an image forming apparatus.
A PVDC film having a thickness of 10 [μm] and a trade name: Kurelap (registered trademark) were prepared as a latent image carrier covering film. The pre-charged photoconductor drum was taken out in the dark, and this PVDC film was wound around the photoconductor drum. The image forming apparatus was mounted on the image forming apparatus to form an image without causing the charging apparatus to function. The image forming apparatus is stopped at the timing when the toner image is formed for one rotation of the photosensitive drum without supplying the paper. When the photosensitive drum was removed and observed, it was recognized that an image was formed. When the wrap film was peeled off from the surface and the toner surface was attached to the paper, it was confirmed that the image was clear.

[Experiment 2]
As Experiment 2, the following experiment was performed using an image MP5000 (manufactured by Ricoh) as an image forming apparatus.
A polymethylpentene (PMP) film having a thickness of 7.5 [μm] as a latent image carrier covering film and a trade name: Couplap (registered trademark) were prepared. When experiments similar to Experiment 1 and Experiment 2 were performed, it was confirmed that images could be formed on the film surface.

表１に示す５種類の透明フィルムのうち、厚さが１００［μｍ］のプリンタック（登録商標）以外は画像形成が可能であることが確認された。このように、厚さが１００［μｍ］のプリンタック（登録商標）では画像形成ができないのは、フィルムの厚みが厚すぎることによって、感光体ドラム上の静電潜像を形成する静電電荷に感応して静電潜像をその表面に保持することができないためと考えられる。 In addition, as experiment 1 similar to experiment 1, it implemented about five types of transparent films including Kurelap (trademark) and Co-wrap (trademark).
Table 1 shows the conditions of the transparent film used in the actual experiment.
Further, “nominal value” in Table 1 is a representative value of the thickness of each transparent film, and “thickness” in Table 1 is an actual measured value.

Of the five types of transparent films shown in Table 1, it was confirmed that image formation was possible except for a printerac (registered trademark) having a thickness of 100 [μm]. As described above, an image cannot be formed with a 100 μm thick Printac (registered trademark) because the film is too thick to form an electrostatic charge on the photosensitive drum. This is because the electrostatic latent image cannot be held on the surface in response to the above.

[Embodiment 2]
In the copying machine 500 of the first embodiment described above, the transfer residual toner whose charge polarity is made uniform by the development recovery auxiliary brush 23 as the polarity control means is collected by the developing roller 4 of the developing device 12 and contributes again to the development. is there. As a configuration for collecting the transfer residual toner by the developing device 12 and contributing to the development again, a toner collecting member different from the developing roller 4 may be provided.
Hereinafter, as an image forming apparatus to which the present invention is applied, the surface of the photosensitive member is coated at least at the development position with a loop-shaped latent image carrier coating film, and the transfer residual toner on the latent image carrier coating film is collected by the developing device. A second embodiment (hereinafter referred to as a second embodiment) of the present invention in which the developing device includes a toner collecting member in addition to the developing roller will be described.
FIG. 4 is an enlarged explanatory view of the image forming unit in the vicinity of the photoconductor 10 of the copying machine main body 100 according to the second embodiment.
The copier 500 according to the second embodiment is different from the copier 500 according to the first embodiment in the configuration of the developing device 12 and the configuration of the polarity control unit. The difference will be described.

  As shown in FIG. 4, in the copying machine main body 100 according to the second embodiment, the coating film F is again attached to the photoconductor 10 on the downstream side in the moving direction of the coating film F from the position where the coating film F is separated from the photoconductor 10. A toner polarity control roller 24 serving as a polarity control unit is disposed at a position upstream of the winding direction of the covering film F with respect to the winding position of the latent image carrier covering film to be wound. The toner polarity control roller 24 is a roller member to which a negative polarity bias having the same polarity as the toner contained in the developer in the developing device 12 is applied by a bias application unit (not shown). By using the same roller member as that of the charging roller 8 as the roller member used for the toner polarity control roller 24, the product cost can be reduced.

Next, the developing device 12 included in the copying machine 500 according to the second embodiment will be described.
Similarly to the first embodiment, the developing device 12 of the second embodiment is a two-component developing device composed of a carrier and a toner. However, the developing device 12 of the second embodiment has a third conveying screw 41 and a toner collecting roller 40 arranged. The developing device 12 is different from the developing device 12 of the first embodiment. The developer conveying path in which the third conveying screw 41 and the toner collecting roller 40 of the developing device 12 are arranged is separated from the developer conveying path in which the developing roller 4 and the first conveying screw 1 are arranged by the first partition plate 43. The second partition plate 44 partitions the developer transport path in which the second transport screw 2 is disposed. The first partition plate 43 and the second partition plate 44 are provided with openings at the end portion in the back direction and the front direction end portion in FIG. 4 and communicate adjacent conveyance paths with the partition plate interposed therebetween.

The copying machine 500 includes a toner bottle (not shown) that stores toner used in the developing device 12, and the toner in the toner bottle is supplied to the developing device 12 by a toner replenishing device (not shown). The toner supplied from a toner supply port (not shown) by the toner supply device is supplied onto a developer composed of a magnetic carrier and toner in a developing container 12a which is a casing of the developing device 12. At this time, the toner is supplied onto the developer conveyed by the second conveying screw 2.
The supplied toner is conveyed in the depth direction of the paper surface in FIG. 4 while being agitated by the second conveying screw 2 together with the developer. As described above, the transport path in which the second transport screw 2 is disposed, the transport path in which the third transport screw 41 is disposed, and the transport path in which the first transport screw 1 is disposed are the planes of FIG. The rear end and the front end of the paper communicate with each other. Then, the developer that has reached the end of the sheet in FIG. 4 by the second conveying screw 2 moves to the conveying path where the third conveying screw 41 is arranged and the conveying path where the first conveying screw 1 is arranged. The first transport screw 1 and the third transport screw 41 are transported from the back direction to the front direction in FIG. Then, the developer that has reached the front end of the paper surface in FIG. 4 by the first transport screw 1 and the third transport screw 41 moves to the transport path where the second transport screw 2 is arranged. As described above, the developer circulates in the developing device 12.

  In the developing device 12 of the second embodiment, the screw pitch, the number of strips, the shaft diameter, the blade diameter, the material, and the rotation speed of the first transport screw 1 and the third transport screw 41 are the same. However, the structure of the 1st conveyance screw 1 and the 3rd conveyance screw 41 is not this limitation. Further, instead of the first transport screw 1 and the third transport screw 41, one transport screw is disposed, and the developer is supplied to the developing roller 4 while transporting the developer with one transport screw, which will be described later. Alternatively, the toner collected by the toner collecting roller 40 may be taken into the developer and stirred and conveyed.

The developer in the transport path transported by the third transport screw 41 is pumped up to the surface of the toner recovery roller 40 by the magnetic force of the toner recovery roller 40 having a magnet built therein. The developing roller 4 and the toner collecting roller 40 are partitioned by a first partition plate 43 so that the developer pumped up on the two rollers is not in contact with each other.
As indicated by an arrow E in the figure, the developer adsorbed by the magnetic force on the surface of the toner collecting roller 40 rotating counterclockwise in the figure is regulated to a fixed amount by the collecting roller doctor 71, and the toner, the magnetic carrier, and the like. Is triboelectrically charged.
The charged developer on the toner collecting roller 40 comes into contact with the coating film F that covers the surface of the photosensitive member 10 at the main pole of the maximum magnetic strength of the toner collecting roller 40. A bias voltage having a polarity opposite to the charging polarity of the toner in the developer (plus polarity) is applied to the toner collecting roller 40, and on the coating film F whose charging polarity is made negative by the toner polarity control roller 24. The transfer residual toner is collected. The developer mixed with the transfer residual toner on the toner collection roller 40 is separated from the surface of the toner collection roller 40 at the agent separation pole, and falls onto the agent surface above the developer conveyed by the third conveyance screw 41. Thereby, the transfer residual toner on the coating film F can be taken into the developer in the developing device 12.

On the other hand, the developer in the transport path transported by the first transport screw 1 is pumped up to the surface of the developing roller 4 by the magnetic force of the developing roller 4 having a built-in magnet. As indicated by an arrow D in the figure, the developer adsorbed by the magnetic force on the surface of the developing roller 4 rotating in the clockwise direction in the figure is regulated to a fixed amount by the developing doctor 70 and the toner and the magnetic carrier are rubbed together. Charged.
The charged developer on the developing roller 4 rises at the main pole of the maximum magnetic strength of the developing roller 4 and comes into contact with the coating film F that covers the surface of the photoreceptor 10 at the developing position. A bias voltage is applied to the developing roller 4, and toner is selectively attached to the surface of the coating film F by the electrostatic latent image on the photoreceptor 10 and developed. The developer on the developing roller 4 after passing through the developing position is separated from the surface of the developing roller 4 at the agent separation pole and falls onto the agent surface above the developer conveyed by the first conveying screw 1.
The timing for starting the rotation of the developing roller 4 and the toner collecting roller 40 at the time of image formation coincides with the timing for starting the rotation driving of the first film stretching roller 201 and the photosensitive member 10 that are driving rollers for the covering film F. .

Next, the bias applied to the toner collecting roller 40 and the developing roller 4 provided in the developing device 12 of Embodiment 2 will be described.
FIG. 5 is an explanatory diagram illustrating an example of the bias applied to the toner collecting roller 40, and FIG. 6 is an explanatory diagram illustrating an example of the bias applied to the developing roller 4. 5 and 6, the vertical axis represents the surface potential of each member of the photoreceptor 10, the toner collection roller 40, and the developing roller 4, and the horizontal axis represents the elapsed time. Each of t ₁ to t _{4 on the} horizontal axis is t ₁ timing of driving start, t ₂ is timing of bias application start to the photosensitive member (the front end of the surface charged by the charging roller reaches a portion facing the roller) timing), t ₃ is the timing when the trailing edge of the charged surface by the bias application end timing (the charging roller to the photosensitive member reaches the opposite end of the roller), t ₄ shows the timing of the drive-end .
Further, the change in potential indicated by the solid line in FIGS. 5 and 6 indicates the change in the surface potential of the photoconductor 10. 5 and 6, Va represents the potential of the non-image portion on the surface of the charged photoconductor 10 (hereinafter, non-image portion potential Va), and Vb represents the potential of the image portion of the charged photoconductor 10 surface. (Hereinafter, image portion potential Vb) is shown.
Further, the change in the potential indicated by the broken line in FIG. 5 indicates the change in the surface potential of the toner collecting roller 40. In the hatched area in FIG. 5, the negative polarity toner is transferred from the photosensitive member 10 side to the toner collecting roller 40. The potential difference acting to move to is shown.
The change in potential indicated by the broken line in FIG. 6 indicates the change in the surface potential of the developing roller 4. In the hatched area in FIG. 6, the negative polarity toner is transferred from the developing roller 4 to the photoconductor 10 side. The potential difference acting to move is shown.

As shown in FIGS. 5 and 6, in this example, the non-image portion potential Va of the photoconductor 10 is −650 [V], and the image portion potential Vb is −50 [V]. As shown in FIG. 5, the surface potential of the toner collection roller 40 by applying a bias is +150 [V]. The start and end of bias application to the toner recovery roller 40 are the drive start timing (t ₁ ) and the drive end timing (t ₄ ) of the toner recovery roller 40. By applying the bias in this way, the negative polarity transfer residual toner on the coating film F is attracted to the toner collection roller 40 side and collected. At this time, mainly in the non-image portion, a potential difference is generated in which the magnetic carrier being developed is attracted to the photoconductor 10 side and adheres to the coating film F. For this, a rare earth magnet is used for the main pole of the toner collecting roller 40 to give a strong magnetic force of 160 [mT] (the ferrite magnet of the main pole of the developing roller 4 is about 100 [mT]), thereby suppressing carrier adhesion. ing. Even when the magnetic carrier adheres to the covering film F, the developing roller 4 moves the developing film 4 on the covering film F at the development position downstream of the moving direction of the covering film F from the position where the toner collection roller 40 and the covering film F face each other. The carrier is collected in the developing container 12a.

  On the other hand, as shown in FIG. 6, the surface potential due to bias application of the developing roller 4 is −500 [V], which is higher than the non-image portion potential Va of the photoconductor 10 in the positive polarity direction. The potential is lower than the image portion potential Vb of the photoreceptor. The start and end of the bias application to the developing roller 4 is a general electrophotographic developing bias timing. By applying such a bias, the negative polarity toner in the developer on the developing roller 4 is attracted to the image portion (electrostatic latent image portion) of the photosensitive member 10 and adheres through the coating film F to develop. Is done. Note that the value of the applied bias described here is not fixed, but is controlled by the use environment of the user. Note that there is a potential difference of several hundred [V] between the surface potential of the toner recovery roller 40 and the surface potential of the developing roller 4, but they are insulated by the first partition plate 43.

  Note that the copier 500 of the second embodiment controls the replenishment of toner to the developing device 12 based on the outputs of the pattern density sensor 6 and the toner density sensor 5 as in the first embodiment.

[Embodiment 3]
In the copying machine 500 according to the first and second embodiments described above, the coating film F that has passed the transfer position B is separated from the surface of the photoreceptor 10 after being separated from the sheet S that is a recording medium. The configuration including the loop-shaped coating film F may be a configuration in which the coating film F that has passed the transfer position B is separated from the surface of the photoreceptor 10 together with the sheet S.
Hereinafter, as an image forming apparatus to which the present invention is applied, the surface of the photosensitive member is coated at least at the development position with a loop-shaped latent image carrier coating film, and the latent image carrier coating film that has passed the transfer position is a latent image together with the recording medium. A third embodiment of the present invention (hereinafter referred to as Embodiment 3) that is separated from the surface of the carrier will be described.

FIG. 7 is a schematic configuration diagram of the entire copying machine 500 according to the third embodiment. FIG. 8 is an explanatory diagram of a state in which the coating film F and the sheet S face each other at the transfer position B of the image forming unit in the vicinity of the photoconductor 10 of the copying machine main body 100 according to the third embodiment. FIG. 9 is an enlarged explanatory view of the heat fixing device 22 provided in the copying machine 500 according to the third embodiment.
The copying machine 500 according to the third embodiment is different from the copying machine 500 according to the first embodiment in the configuration in which the loop-shaped coating film F is wound up to the heat fixing device 22 and the configuration in which the polarity control unit is not provided. Since they are common, descriptions of common configurations are omitted, and differences are described.

  As with the first and second embodiments, the coated film conveyance device 20 included in the copying machine 500 according to the third embodiment includes a loop-shaped coated film F, a first film stretching roller 201, and a second film stretching roller 202. The third film stretching roller 203 and the fourth film stretching roller 204 are provided, and the covering film F is moved endlessly in accordance with the surface movement of the photoreceptor 10. Moreover, also in the covering film conveyance apparatus 20 of Embodiment 3, the 1st film stretching roller 201 is a drive roller.

The covering film F transported by the covering film transporting device 20 is wound so as to be in close contact with the surface of the photoreceptor 10 through the surface of the winding roller 81 and covers the surface of the photoreceptor 10. That is, also in the third embodiment, the position where the winding roller 81 and the photoconductor 10 face each other is the latent image carrier covering film winding position, as in the first embodiment. The coating film F sticks to the photoconductor 10 by the pressing force of the winding roller 81 and is conveyed downstream as it is, and passes through the development position and the transfer position B with the surface of the photoconductor 10 covered. Further, in the copying machine 500 of the third embodiment, as shown in FIGS. 7 and 9, the coating film F that has passed the transfer position B also passes through the fixing nip of the thermal fixing device 22.
Inside the loop of the covering film F, the photoconductor 10, the charging roller 8, and the laser writing device 47 are arranged, and further, the heating roller 30 of the heat fixing device 22 is arranged. Further, the developing device 12 and the transfer device 13 are disposed outside the loop of the covering film F, and further, the pressure roller 32 of the heat fixing device 22 is disposed. The developing roller 4 of the developing device 12, the transfer belt 17 of the transfer device 13, and the pressure roller 32 of the heat fixing device 22 circumscribe the coating film F, and the heating roller 30 of the heat fixing device 22 contacts the coating film F. Inscribed.
Further, in the coated film conveying apparatus 20 of the first embodiment, the third film stretching roller 203 is inscribed in the covering film F, but in the third embodiment, the third film stretching roller 203 is circumscribed in the covering film F. It is a configuration.

  The processes from reading the original content when copying using the copying machine 500 of the third embodiment to forming a toner image on the surface of the coating film F on the surface of the photoreceptor 10 are the copying machine 500 of the first embodiment. It is the same. The process until the sheet S in the sheet cassette 61 or on the manual feed tray 67 is fed to the right side of the photoreceptor 10 is the same as that of the copier 500 of the first embodiment.

  The sheet S fed to the right side of the photoconductor 10 covers the surface of the photoconductor 10 at the transfer position B, and overlaps with the coating film F on which the toner image is formed. In the copying machine 500 according to the third embodiment, a transfer bias is applied to the transfer roller 7 by a bias applying device (not shown), and a transfer electric field is formed between the transfer roller B and the photoconductor 10. As shown in FIG. 8, the toner image facing the sheet S at the transfer position B is sandwiched between the covering film F and the sheet S. However, the photosensitive member 10 is electrostatically moved by the transfer electric field. The state moves from the surface of the covering film F to be coated to the sheet S, and the toner image on the sheet S is transferred. The sheet S on which the toner image has been transferred is separated from the photoreceptor 10 together with the coating film F, and is conveyed to the thermal fixing device 22.

In the copying machine 500 according to the third embodiment, the coating film F is stretched between the surface of the photoreceptor 10 and the heating roller 30. For this reason, at the transfer position B, the covering film F is pulled in the direction of the heating roller 30 arranged in the same direction as the conveyance direction of the sheet S, and separated from the surface of the photoreceptor 10 together with the sheet S. In the copying machine 500 according to the third embodiment, the configuration in which the covering film F is stretched between the heating roller 30 and the photosensitive member 10 functions as a latent image carrier covering film separating unit.
The surface of the photoreceptor 10 from which the coating film F has been separated at the transfer position B is in a state ready for the next image formation starting from the charging roller 8 by removing the residual potential by a neutralizing device (not shown).

On the other hand, the sheet S to which the toner image has been transferred and conveyed to the thermal fixing device 22 together with the coating film F is passed through a fixing nip formed by the heating roller 30 and the pressure roller 32 together with the coating film F. In the heat fixing device 22, while the coating film F and the sheet S are conveyed to these rollers, heat and pressure are applied to fix the toner image to the sheet S.
In the copying machine 500 of the third embodiment, the coating film F is stretched between the surface of the heating roller 30 on the downstream side in the surface movement direction from the fixing nip and the third film stretching roller 203. For this reason, the covering film F is pulled in the direction of the third film stretching roller 203 arranged in a direction different from the conveying direction of the sheet S, and the covering film F is separated from the sheet S along the surface of the heating roller 30. . The sheet S that has passed through the fixing nip and separated from the coating film F passes through the discharge roller 35 and is discharged and stacked on the discharge stack portion 39. Further, the coating film F separated from the sheet S after passing through the fixing nip passes through the position where it is stretched by each stretching roller, and comes into close contact with the surface of the photoreceptor 10 again through the surface of the winding roller 81. And the surface of the photoreceptor 10 is covered. Image formation is continued by repeating this process.

In the copying machine 500 according to the third exemplary embodiment, the toner image is transferred from the top of the photoreceptor 10 to the sheet S from the development position where the developing roller 4 of the developing device 12 and the surface of the photoreceptor 10 face each other in the surface movement direction of the photoreceptor 10. Until the transfer position B moves, the coating film F covers the surface of the photoreceptor 10. Then, the coating film F is separated from the surface of the photoreceptor 10 together with the toner image at the transfer position B. Further, the coating film F separated from the surface of the photoconductor 10 together with the toner image passes through the thermal fixing device 22, passes through the stretching position by each stretching roller, and then forms the latent image on the photoconductor 10 before development. It is the structure which wraps around the surface again. With such a configuration, in the copying machine 500, the toner image is formed on the coating film F that covers the photoreceptor 10, and the toner does not directly adhere to the surface of the photoreceptor 10. For this reason, a photoconductor cleaning means for cleaning the surface of the photoconductor 10 is unnecessary.
The copying machine 500 according to the third exemplary embodiment is a monochrome image forming apparatus that includes one photoconductor and one developing device. However, a full-color image forming apparatus in which four developing devices are arranged on one photoconductor. Even so, a configuration in which the latent image carrier covering film is wound around the surface of the photosensitive member is applicable.

Since heat is applied in the thermal fixing device 22, in the configuration in which the coating film F is applied to the fixing device, the separation between the coating film F and the sheet S and the separation between the coating film F and the heating roller 30 are performed. Is concerned.
However, in the copying machine 500 according to the third embodiment, since it was possible to satisfactorily separate the sheet S and the heating roller 30 without taking any special measures, it is not considered to be a great concern.

First, regarding the separability between the covering film F and the heating roller 30, the covering film F is on a loop, and further, if the covering film F is not tensioned in an image forming process such as transfer, the image is defective. Therefore, it is considered that a certain amount of tension is applied to the coating film F. Further, the coating film F can be separated from the heating roller 30 by a physical force by a tensile force from the third film stretching roller 203 disposed downstream of the heating roller 30 in the moving direction of the coating film F. it is conceivable that.
As for the separation between the covering film F and the sheet S, when the sheet S is separated from the covering film F, the covering film F forms a loop in a state where tension is applied in the image forming process as described above. Therefore, it is considered that the coating film F is integrated with the heating roller 30 at a position where the sheet S and the coating film F are separated. At this time, the relationship between the coating film F of the third embodiment and the heating roller 30 can be considered to be equivalent to the relationship between the fixing belt and the heating roller of the conventional fixing device. For this reason, in the copying machine 500 according to the third embodiment, the separation of the coating film F and the sheet S is performed using an extreme separation or a separation plate as in the separation of the fixing belt and the recording medium in the conventional fixing device. Can be separated.

In the copying machine 500 according to the third embodiment, when the offset toner remains on the coating film F separated from the sheet S by the thermal fixing device 22, the surface of the coating film F is contaminated by the offset toner in the next development and charging process. As a result, problems such as developability and chargeability may occur.
Here, in the heat fixing device 22, if the releasability of the heating roller 30 or the pressure roller 32 is poor, a part of the toner adheres to the heating roller 30 or the pressure roller 32 and an offset occurs. appear.
As a fixing device of a conventional image forming apparatus that does not include a latent image carrier covering film, a release layer is formed on the outer periphery of the fixing device so that a good release property can be obtained with a fixing roller or a pressure roller. A configuration in which an oil application roller for applying silicone oil to the release layer is known.
However, with such a configuration, it is difficult to completely prevent the occurrence of offset. Then, a small amount of offset toner remains on the fixing roller or the pressure roller, and the surface of the oil application roller is soiled with toner or paper powder. May be soiled. When the surface of the oil application roller is fouled, the fouled offset toner is reversely transferred to the fixing roller or the pressure roller to cause image fouling on the recording paper.

Such a problem can be improved by the configuration of the fixing device described in JP-A-7-234600 and JP-A-9-6173.
In the fixing device described in Japanese Patent Application Laid-Open No. 7-234600, an oil application roller is formed on a roller base formed of a foam, and countless fine holes are formed in a fluororesin having the same quality as a release layer of a fixing roller or a pressure roller. And a cleaning member for cleaning the surface of the oil application roller.
In addition, the fixing device described in Japanese Patent Laid-Open No. 9-6173 is provided with a cleaning roller for cleaning the surface of the oil application roller and a blade for removing foreign matter adhering to the outer peripheral surface of the cleaning roller.
The thermal fixing device 22 of the copying machine 500 according to the third exemplary embodiment is a configuration studied using the principle of the configuration described in these publications. As shown in FIG. 9, in the heat fixing device 22 of the copying machine 500 according to the third embodiment, the coating film F is wound around the heating roller 30 corresponding to the fixing roller described in the above publication, and the pressure roller 32 is traced. The oil application roller 82 is in contact, and the cleaning roller 83 is in contact with the trace amount oil application roller 82.
With such a configuration, the occurrence of offset can be prevented and good image formation can be performed over time.

Note that the copying machine 500 according to the third embodiment has a configuration in which the surface of the coating film F is cleaned before the coating film F separated from the sheet S by the thermal fixing device 22 is wrapped around the photoreceptor 10 again. Absent. Even when the coating film F passes through the thermal fixing device 22 as in the third embodiment, the surface of the coating film F is cleaned before the coating film F separated from the sheet S wraps around the photoreceptor 10 again. The structure provided with a cleaning means may be sufficient.
As an example of this cleaning means, the third film stretching roller 203 may be used as a cleaning roller so as to remove offset toner on the surface of the coating film F. In such a configuration, the offset toner on the coating film F is soft when passing through the thermal fixing device 22 and can be easily removed by a configuration where it is wiped off by a cleaning roller. The cleaning means for the covering film F is not limited to such a configuration, and any means can be used as long as it can remove the offset toner on the covering film F after passing through the thermal fixing device 22. It may be a simple configuration.

[Embodiment 4]
The copying machine 500 according to the third embodiment described above has a configuration in which the loop-shaped coating film F passes through the fixing unit of the thermal fixing device 22 and the heating member uses the roller-shaped heating roller 30. The heating member constituting the fixing unit is not limited to a roller-shaped member.
Hereinafter, as an image forming apparatus to which the present invention is applied, at least the surface of the photosensitive member at the development position is coated with a loop-shaped latent image carrier coating film, and the latent image carrier coating film that has passed the transfer position is a latent image together with the recording medium. A fourth embodiment of the present invention (hereinafter referred to as implementation) in which the latent image carrier-covered film separated from the surface of the carrier is passed through the fixing device together with the recording medium, and the heating member is different from the roller shape. (Referred to as form 4).
FIG. 10 is an enlarged explanatory view of the heat fixing device 22 provided in the copying machine main body 100 according to the fourth embodiment.
The copier 500 of the fourth embodiment is different from the copier 500 of the third embodiment in the structure of the heating member of the thermal fixing device 22, and the other configurations are the same. explain.

  As shown in FIG. 10, the thermal fixing device 22 according to the third exemplary embodiment includes a ceramic heater 90 including a plate-like heating body 91 supported by a heater support member 92 as a heating member. The covering film F includes a pressure roller 32 at a position facing the heating body 91, and a fixing nip is formed between the heating body 91 and the pressure roller 32. Further, the thermal fixing device 22 includes a fixing inlet roller 93 on the upstream side in the moving direction of the covering film F with respect to the fixing nip, and a fixing outlet roller 94 on the downstream side in the moving direction of the covering film F with respect to the fixing nip.

The covering film F is an endless belt-like heat-resistant film, and is stretched by a fixing inlet roller 93 and a fixing outlet roller 94 that are arranged in parallel to a heating body 91 that is fixedly supported by a heater support member 92. It is built. The covering film F is stretched in a tensioned state by these two rollers (93, 94), the stretching rollers (201 to 204), the winding roller 81, and the photoreceptor 10. . Further, since the covering film F comes into close contact with the sheet S carrying the unfixed toner from the photoreceptor 10 and enters the thermal fixing device 22 together with the sheet S, the sheet S carrying the unfixed toner does not wrinkle, meander, or speed delay. It can pass through the thermal fixing device 22.
The pressure roller 32 is a roller member having an elastic layer with good releasability, such as silicon rubber. The pressure roller 32 is in contact with the heating body 91 with the covering film F interposed therebetween, and is applied with a total pressure 39. The fixing nip is formed by opposing pressure contact with a contact pressure of 2 [N] to 9.8 [N].
Further, since the coating film F used in the copying machine 500 is repeatedly used for heat fixing of a toner image, it is preferable to have a thin film having excellent heat resistance, releasability and durability.

The flat substrate constituting the heating body 91 of Embodiment 4 is made of a material having high thermal conductivity and high electrical resistivity, such as alumina, and has a thickness of 0.6 [mm], a width of 10 [mm], and a length. It is 310 [mm], and the heating element 91 has a resistance heating element that extends in the longitudinal direction (the front-rear direction in FIG. 10) on the surface that contacts the coating film F.
The heater support member 92 is made of, for example, PPS (Polyphenylene Sulfide), PAI (Polyamideimide), PI (Polyimide), PEEK (Polyetheretherketone), a high heat resistant resin such as a liquid crystal polymer, these resins and ceramics, metal, It can be composed of a composite material such as glass. The ceramic heater 90 provided in the thermal fixing device 22 according to the fourth embodiment supplies the maximum power when starting up, thereby heating the heating body 91 to a vicinity of a predetermined temperature sufficient to fix the toner image on the sheet S.

When the coating film F is stretched around the heating roller 30 as a heating member like the thermal fixing device 22 provided in the copying machine 500 of the third embodiment described above, the coating film F is a fixing nip region for fixing toner. In addition to being stretched around the heating roller 30, the entire region in contact with the surface of the heating roller 30 is heated, and the coating film F may be damaged by heat.
On the other hand, if the structure is such that the ceramic heater 90 of the fourth embodiment locally heats the coating film F so as to heat the coating film F only at the fixing nip, damage to the coating film F due to heating is reduced. . Further, the rising time of fixing can be shortened as compared with the configuration in which heating is performed by a heating roller.

The thermal fixing device 22 may be configured to include a cooling unit that cools the coating film F that has passed through the fixing nip for heating and fixing the toner image to the sheet S.
FIG. 11 is an enlarged explanatory view of the heat fixing device 22 having a configuration in which the heat fixing device 22 according to the fourth embodiment described with reference to FIG. 10 includes a heat sink 95 as a cooling unit.
In the thermal fixing device 22 shown in FIG. 11, the coating film F is cooled by the sheet S heat sink 95 carrying the toner image that has passed through the fixing nip. The covering film F that has passed through the portion facing the heat sink 95 is pulled in the direction of the third film stretching roller 203 disposed on the downstream side of the moving direction of the covering film F with respect to the fixing outlet roller 94, and the fixing outlet roller 94. Is separated from the sheet S along the surface.

Next, the configuration for separating the coating film F and the sheet S after cooling will be described in more detail.
The sheet S that is heated and pressurized and is in close contact with the belt-shaped coating film F is conveyed to a portion facing the heat sink 95 that is a cooling unit as the coating film F moves. In the cooling unit, the heat sink 95 is brought into contact with the back surface of the coating film F to absorb the thermal energy of the sheet S that is in close contact with the coating film F. Then, air is passed through the fin surface of the heat sink 95, and heat energy is released into the air. That is, the sheet S is cooled to a predetermined temperature by continuously transferring thermal energy from the covering film F and the sheet S to the heat sink 95 and further into the air.
Then, after the covering film F and the sheet S are cooled to a predetermined temperature, the sheet S is separated from the covering film F. Thus, the coating film F and the sheet S are separated after being cooled to a predetermined temperature. As a result, the toner and the resin on the surface of the paper are cooled to near the glass transition point temperature, and the mirror surface of the surface of the coating film F can be copied to finish the glossy print. The image can be glossed.

On the other hand, when the sheet S is separated from the coating film F without being sufficiently cooled, the toner and the resin on the surface of the sheet S are pulled to the coating film F by the adhesive force to the coating film F during the separation, and the surface of the sheet S In addition, minute irregularities are continuously generated on the surface of the toner image, and the glossiness is lowered. In the temperature range where the glossiness is stable, the toner and the resin on the surface of the sheet S are cooled to increase the cohesive force. Therefore, when the sheet S is separated from the coating film F, the resin is divided and the coating film is separated. The surface of the coating film F can always be maintained in a mirror state without remaining on the F surface.
As described above, it is possible to obtain a high-gloss image by cooling with the coating film F and heating, and further, the sheet S and the coating film F can be satisfactorily separated by cooling.
Further, in the copying machine 500 of the fourth embodiment, the coating film F has a loop shape, and the coating film F is repeatedly used. Therefore, the coating film F reaches the image forming unit again after fixing by cooling. Sometimes it does not have heat, and it is possible to prevent problems caused by the temperature of the image forming section such as the developer in the developing device 12 and the photoconductor 10 rising.

Even if the heating member is not in the form of a roller as in the heat fixing device 22 of the fourth embodiment, a small amount of oil application roller 82 or cleaning is applied to the pressure roller 32 as in the heat fixing device 22 of the third embodiment. The structure which arrange | positions the roller 83 may be sufficient.
Further, as shown in FIG. 11, the configuration including the cooling means for cooling the coating film F after passing through the fixing position is not limited to the configuration in which the heating member is a ceramic heater as in the fourth embodiment, but the third embodiment. As described above, any configuration that performs heat fixing, such as a configuration of a heating roller, is applicable.

  In the first to fourth embodiments described above, the winding roller 81 is positioned downstream of the latent image forming position where the electrostatic latent image is formed and upstream of the developing position in the surface movement direction of the photoconductor 10. And the covering film F is brought into close contact with the surface of the photosensitive member 10 to cover the surface of the photosensitive member 10. The position where the surface of the photoconductor 10 is coated may be upstream of the development position. Between the uniform charging position uniformly charged by the charging roller 8 and the electrostatic latent image forming position, or the uniform charging. It may be upstream from the position. However, as in Embodiments 1 to 4 described above, the surface of the photoreceptor 10 on which charging and formation of an electrostatic latent image have been performed is covered with the coating film F, so that the electrostatic latent image can be obtained evenly during charging. There is no influence of the coating film F at the time of formation, and a relatively high-quality image can be formed.

As described above, the copying machine 500 according to each of the embodiments described above includes the photosensitive member 10 that is a latent image carrier that moves on the surface, the charging roller 8 that is a charging unit that uniformly charges the surface of the photosensitive member 10, and the photosensitive member 10. The latent image forming means for forming an electrostatic latent image is a laser writing device 47 and a toner image forming means for supplying toner to the electrostatic latent image formed on the photoreceptor 10 to form a toner image. A developing device 12, and a coating film F, which is a latent image carrier coating film, covers the surface of the photoreceptor 10 at least at a developing position that is a toner image forming position where a toner image is formed by the developing device 12. The winding roller 81 which is a coating film winding means for winding the coating film F around the surface of the photoconductor 10 and the surface of the photoconductor 10 covered with the coating film F are again covered by the winding roller 81. Before reaching the position where the film F can be wound, the coating film separating means for separating the coating film F that has passed the development position from the surface of the photoconductor 10 in a state where the surface of the photoconductor 10 is coated, and the coating film at the development position A transfer device 13 that is a transfer unit that transfers the toner image formed on F to a sheet S that is a recording medium, and the covering film F separated from the surface of the photoconductor 10 is wound around the surface of the photoconductor 10 again. The covering film F is configured in an endless loop shape. For this reason, the coating film F that is wound around the surface of the photoconductor 10 as in the configuration in which the roll-shaped coating film F is wound around the surface of the photoconductor 10 is not lost. The burden of replacing the covering film F can be reduced. Further, since the coating film F covers the surface of the photoconductor 10 at least from the development position to the transfer position B where the toner image is transferred to the sheet S, the toner does not directly adhere to the surface of the photoconductor 10 and the photoconductor 10 is exposed. The configuration for cleaning the body 10 is not required, and the life of the photoreceptor 10 can be extended.
In the configuration in which a roll-shaped coating film F is wound around the surface of the photoconductor 10 and the coating film F is not attached to the sheet S and only the sheet S on which the toner image is fixed is discharged, the photoconductor 10 A space for collecting the separated coating film F is required. However, in the case of the copying machine 500 according to each embodiment to which the present invention is applied, the coating film F is repeatedly used in a loop shape. Is also unnecessary, saving space. Further, compared to a configuration in which the covering film F is not in a loop shape, user maintenance such as replenishment and disposal of the covering film F and an economical burden can be reduced.
In the copying machine 500 according to the first and second embodiments, the configuration in which the covering film F is stretched between the third film stretching roller 203 and the photosensitive member 10 functions as a latent image carrier covering film separating unit. .
In the copying machine 500 according to the third embodiment, the configuration in which the coating film F is stretched between the heating roller 30 and the photoconductor 10 functions as a latent image carrier covering film separating unit, and the copying machine 500 according to the fourth embodiment. Then, the configuration in which the covering film F is stretched between the fixing entrance roller 93 and the photosensitive member 10 functions as a latent image carrier covering film separating unit.

  Further, in the copying machine 500 of each of the above-described embodiments, the winding roller 81 is located at the developing position downstream of the latent image forming position where the latent image is formed by the laser writing device 47 in the surface movement direction of the photoconductor 10. The coating film F is wound around the surface of the photoconductor 10 on the upstream side of the surface movement direction of the photoconductor 10, and the coating film separating means is arranged so that the charging roller 8 is uniformly charged by the charging roller 8. In this configuration, the coating film F is separated from the surface of the photoreceptor 10 on the upstream side in the surface movement direction. With this configuration, the photosensitive film 10 is not uniformly charged through the coating film F with respect to the coating film F in which a small amount of transfer residual toner may be adhered, but before the coating film F is wound. By charging the photoconductor 10, it is possible to avoid the toner additive from being fixed to the coating film F by charging. Further, by forming the electrostatic latent image by irradiating the photosensitive member 10 with the writing light 3 before the covering film F is wound, a latent image that is sharper than that exposed through the film can be obtained.

  The transfer device 13 of the copier 500 according to the first and second embodiments includes a transfer roller 7 that forms a transfer nip with the photoconductor 10 with the coating film F sandwiched at the transfer position B. At the entrance side, the covering film F and the sheet S enter, respectively, and at the transfer nip, the sheet S contacts the latent image carrier via the covering film F and is formed between the photosensitive member 10 and the transfer roller 7. The toner image on the covering film F is moved to the sheet S by the electric field, and the sheet S is separated from the covering film F covering the surface of the photoconductor 10 on the exit side of the transfer nip, and then from the surface of the photoconductor 10. Since the covering film F is separated, when the covering film F is separated from the photoreceptor 10, the covering film F is separated from the sheet S on which the toner image is placed. It is possible to prevent the disturbance of the toner image due to separation discharge when separating from 0.

  Further, the transfer device 13 of the copying machine 500 according to the third and fourth embodiments includes a transfer roller 7 that forms a transfer nip with the photoreceptor 10 with the coating film F sandwiched at the transfer position B, and the transfer nip of the transfer nip. At the entrance side, the covering film F and the sheet S enter, respectively, and at the transfer nip, the sheet S contacts the latent image carrier via the covering film F and is formed between the photosensitive member 10 and the transfer roller 7. The toner image on the coating film F is moved to the sheet S by the electric field, and the coating film F is separated from the photoreceptor 10 together with the sheet S on the exit side of the transfer nip. Since the sheet S on which the image is placed and the covering film F are in close contact with each other with the toner image interposed therebetween, the toner image caused by peeling discharge when the covering film F is separated from the photoconductor 10 is used. Les can be prevented.

  Further, in the copying machine 500 according to the third and fourth embodiments, the coating film F that has passed through the transfer nip together with the sheet S is a fixing unit of the thermal fixing device 22 that heats and fixes the toner image on the sheet S. The sheet enters the nip together with the sheet S, and after passing through the fixing nip, is separated from the sheet S. In particular, in the copying machine 500 according to the third embodiment, since the covering film F is stretched from the photoconductor 10 to the heating roller 30, the sheet S moving in close contact with the covering film F is conveyed from the transfer position to the fixing position. The path is stable and the occurrence of fixing abnormality such as wrinkles can be suppressed. In particular, in the copying machine 500 according to the fourth embodiment, since the covering film F is stretched from the photosensitive member 10 to the fixing outlet roller 94 on the downstream side of the fixing nip, the sheet S that moves in close contact with the covering film F. The conveyance path from the transfer position to the fixing position is stabilized, and the occurrence of fixing abnormality such as wrinkles can be suppressed.

  The heat fixing device 22 according to the third embodiment includes a heating roller 30 having a heat source therein, and a pressure roller 32 that contacts and pressurizes the heating roller 30, and the contact between the heating roller 30 and the pressure roller 32. By forming a fixing nip as a fixing part at the part, the covering film F can be wound around the heating roller 30 and used as a fixing belt of a conventional fixing device, thereby realizing stable fixing. can do. In addition, the covering film F is hung on the heating roller 30 to separate the fixing belt and the transfer paper of the conventional fixing device according to the curvature of the covering film F along the heating roller 30 and the stiffness of the sheet S. Similarly, the covering film F and the sheet S can be easily separated.

  The thermal fixing device 22 of Embodiment 4 includes a plate-like heating body 91 that faces the coating film F at a fixing nip that is a fixing unit and extends in a direction orthogonal to the moving direction of the coating film F. The length of the heating body 91 in the moving direction of the covering film F is substantially the same as the nip width of the fixing nip, and the covering film F is wound around the heating roller 30 of the heating member so that the covering film F and the heating roller 30 come into contact with each other. Compared with the roller fixing in which the covering film F is heated in the entire area, the heating to the covering film F locally causes less damage to the covering film F. Furthermore, since the coating film F is thin, the heat capacity is low, heating during standby is not required, power consumption can be suppressed, and the fixing rise time can be shortened.

  Further, the thermal fixing device 22 described with reference to FIG. 11 of Embodiment 4 covers the downstream side in the moving direction of the coating film F from the fixing nip and the upstream side from the position where the coating film F separates from the sheet S. Since the heat sink 95 which is a film cooling means for cooling the film F is provided, the coating film F and the sheet S can be separated after the toner image on the sheet S is cooled and solidified. Thereby, the improvement of the separation of the coating film F and the sheet S after fixing can be achieved. Furthermore, it is possible to suppress the occurrence of problems caused by the coating film F that is repeatedly used reaching the image forming portion while being heated by fixing.

Further, in the copying machine 500 including the loop-shaped coating film F, as described in the first exemplary embodiment, after the coating film F is separated from the surface of the photoreceptor 10, the transfer of the toner image onto the sheet S is finished. Thereafter, film cleaning means for removing foreign matters such as transfer residual toner on the surface of the coating film F until it is wound around the surface of the photoreceptor 10 again by mechanical rubbing such as a blade or a brush may be disposed. . By providing the film cleaning means, it is possible to prevent problems that occur when the coating film F having foreign matter attached to the surface reaches the image forming process or the transfer process.
Further, in the configuration in which the coating film F is rotated to the fixing together with the sheet S as in the copying machine 500 of the third and fourth embodiments, the coating film F is separated from the surface of the photoconductor 10 and further passes through the thermal fixing device 22. After that, film cleaning means for removing foreign matters such as offset toner on the surface of the coating film F before being wound around the surface of the photoreceptor 10 again may be arranged. Accordingly, by removing the toner remaining on the coating film F as an offset toner, it is possible to prevent the occurrence of problems when the coating film F is repeatedly used.
In the configuration in which the covering film F is rotated together with the sheet S until fixing as in the copying machine 500 of the third and fourth embodiments, there is a fixing device that includes a conventional fixing belt that does not require cleaning of the fixing belt. As with the case, it may not be necessary to clean the coating film F.

Further, the copying machine 500 according to the first and second embodiments is wound around the surface of the photoconductor 10 again after the coating film F is separated from the surface of the photoconductor 10 and after the transfer of the toner image onto the sheet S is completed. The developing recovery assisting brush 23 and the toner, which are polarity control means for aligning the charged polarity of the toner existing on the surface of the coating film F until it is applied with the negative polarity of the same polarity as the toner contained in the developer in the developing device 12 A polarity control roller 24 is provided. By making the toner remaining on the coating film F as the transfer residual toner the same polarity as the toner in the developer in the developing device 12, the transfer residual toner can be recovered at the development position, and the toner recovered as the transfer residual toner By discarding, wasteful toner can be eliminated and the user's economic burden can be reduced.
In addition, as long as the polarity of the toner on the covering film F is uniform, the transfer residual toner on the covering film F can be electrostatically removed without being limited to the configuration of collecting by the developing device 12. By electrostatically removing the transfer residual toner on the coating film F, development that is faithful to the latent image can be performed.

  Further, the copier 500 of the first embodiment has a brush roller shape to which a negative polarity voltage having the same polarity as that of the toner in the developer in the developing device 12 that is toner used in toner image formation is applied as polarity control means. By providing the development recovery auxiliary brush 23, the charging polarity of the toner on the covering film F can be made negative.

  Further, the copier 500 according to the second embodiment has a roller-like shape to which a negative polarity voltage having the same polarity as that of the toner in the developer in the developing device 12 that is toner used in toner image formation is applied as polarity control means. By providing the toner polarity control roller 24, the charging polarity of the toner on the coating film F can be made to be negative. Furthermore, since the roller-shaped charging roller 8 is provided as a charging means, and the charging roller 8 and the toner polarity control roller 24 are a common roller member, the product cost can be reduced and the economic burden on the user can be reduced.

  Further, in the copying machine 500 according to the second embodiment, the development is performed on the downstream side in the moving direction of the covering film F from the position where the toner polarity control roller 24 aligns the charging polarity of the toner existing on the surface of the covering film F with the predetermined charging polarity. By providing a toner collecting roller 40 that constitutes a toner collecting means on the film that collects toner having a negatively charged polarity upstream of the position in the moving direction of the covering film F, the toner is transferred onto the covering film F as a transfer residual toner. Since the remaining toner can be collected before development, development that is faithful to the latent image by the well-charged toner in the developing device 12 can be performed.

  Further, in the copying machine 500 according to the second embodiment, the toner recovery roller 40 forms a toner image so as to face the photoconductor 10 covered with the coating film F on the upstream side of the surface movement direction of the photoconductor 10 with respect to the development position. As a device that comprises a rotatable sleeve member disposed within the developing device 12 as a means and a magnet roller that is disposed inside the sleeve member and includes a plurality of magnetic poles, and further constitutes a toner collecting means on the film, a toner A toner recovery voltage application power source (not shown) is provided as voltage application means for applying a negative polarity voltage opposite to the predetermined charging polarity to the sleeve member of the recovery roller 40. In such a configuration, only the sleeve member of the toner recovery roller 40 rotates, so that the developer pumped on the surface of the sleeve member by the magnetic force of the pumping pole formed by the magnetic poles of the magnet roller is exchanged with the coating film F. The toner having a negative charge polarity on the surface of the coating film F is taken into the developer on the surface of the sleeve member by the positive polarity bias applied to the sleeve member at the opposite portion. it can. Then, the developer that has taken in the toner on the coating film F is transported to the agent separating pole formed by the magnetic pole of the magnet roller by the rotation of the sleeve member and dropped into the developer in the developing device 12, so A configuration for reusing toner can be realized. For this reason, the untransferred toner again contributes to development, and waste toner is eliminated, thereby reducing the economic burden on the user.

  In the copier 500 of the second embodiment, the surface movement direction of the sleeve member at the position where the sleeve member of the toner collecting roller 40 faces the photoreceptor 10 covered with the coating film F is the surface movement direction of the coating film F. On the other hand, when the sleeve member rotates so as to be in the opposite direction (the direction of arrow E in FIG. 4), the moving direction of the magnetic spikes of the developer carried on the surface of the toner recovery roller 40 is the movement of the coating film F. Since the developer on the toner collection roller 40 contacts the coating film F with a counter, the transfer residual toner on the coating film F can be collected well. As a result, the transfer residual toner can be more reliably collected, and development faithful to the latent image can be performed. In the developing device 12 of the second embodiment, the surface movement direction of the sleeve member of the developing roller 4 at the development position is forward (direction of arrow D in FIG. 4) with respect to the surface movement direction of the coating film F. When the sleeve member is rotated, the moving direction of the magnetic spike of the developer carried on the surface of the developing roller 4 becomes the forward direction with respect to the moving direction of the coating film F.

DESCRIPTION OF SYMBOLS 1 1st conveyance screw 2 2nd conveyance screw 3 Writing light 4 Developing roller 5 Toner density sensor 6 Pattern density sensor 7 Transfer roller 8 Charging roller 10 Photoconductor 12 Developing device 12a Developing container 13 Transfer device 15 First stretching roller 16 1st Bi-strand roller 17 Transfer belt 20 Cover film transport device 21 Registration roller 22 Thermal fixing device 23 Development recovery auxiliary brush 24 Toner polarity control roller 30 Heating roller
32 Pressure roller 35 Discharge roller 39 Discharge stack unit 40 Toner collection roller 41 Third transport screw 43 First partition plate 44 Second partition plate 47 Laser writing device 48 Rotating polygon mirror 49 Polygon motor 50 Scanning optical system 53 Light source 54 Mirror 55 Image-forming optical lens 56 Image sensor 57 Contact glass 61 Sheet cassette 62 Call roller 63 Supply roller 64 Separation roller 66 Sheet conveyance roller 67 Manual feed tray 68 Manual paper feed unit 70 Development doctor 71 Collection roller doctor 90 Ceramic heater 81 Winding roller 82 Trace oil application roller 83 Cleaning roller 91 Heating body 92 Heater support member 93 Fixing entrance roller 94 Fixing exit roller 95 Heat sink 100 Copying machine main body 200 Image reading device 201 First film stretching roller 202 Film stretching roller 203 third film tension roller 204 fourth film tension roller 300 sheet bank 400 automatic document feeder
500 Copier B Transfer Position C Sheet Conveying Device F Coating Film S Sheet R Sheet Conveying Route R1 Supplying Route R2 Manual Feeding Route

JP 2008-032851 A

Claims (15)

A latent image carrier that moves on the surface;
Charging means for uniformly charging the surface of the latent image carrier;
Latent image forming means for forming an electrostatic latent image on the latent image carrier;
An image forming apparatus comprising toner image forming means for supplying toner to an electrostatic latent image formed on the latent image carrier to form a toner image,
The latent image carrier coating film is coated on the surface of the latent image carrier so that the latent image carrier coating film covers the surface of the latent image carrier at least at the toner image forming position where the toner image is formed by the toner image forming means. A covering film winding means for winding;
Before the surface of the latent image carrier coated with the latent image carrier coated film reaches the position where the latent image carrier coated film is wound again by the coated film winding means, the surface of the latent image carrier is Coating film separating means for separating the latent image carrier-covered film that has passed through the toner image forming position in a coated state from the surface of the latent image carrier;
Transfer means for transferring the toner image formed on the latent image carrier-covered film at the toner image forming position to a recording medium;
An image characterized in that the latent image carrier-coated film is configured in an endless loop so that the latent image carrier-coated film separated from the surface of the latent image carrier is wound around the surface of the latent image carrier again. Forming equipment. The image forming apparatus according to claim 1.
The covering film wrapping means is located on the downstream side of the surface moving direction of the latent image carrier from the latent image forming position where the latent image is formed by the latent image forming means, and is more latent than the toner image forming position. Wrap the latent image carrier covering film around the surface of the latent image carrier upstream of the body surface movement direction,
The covering film separating means removes the latent image carrier covering film from the surface of the latent image carrier upstream of the uniform charging position uniformly charged by the charging means in the surface movement direction of the latent image carrier. An image forming apparatus characterized by being configured to be separated. The image forming apparatus according to claim 1 or 2,
The transfer means includes a transfer roller that forms a transfer nip between the latent image carrier covering film and the latent image carrier.
The latent image carrier-coated film and the recording medium enter the entrance side of the transfer nip, respectively, and the recording medium abuts the latent image carrier through the latent image carrier-coated film at the transfer nip. On the exit side of the transfer nip, the recording medium separates from the latent image carrier-coated film that covers the surface of the latent image carrier, and then the latent image carrier-coated film is separated from the surface of the latent image carrier. An image forming apparatus that is separated. The image forming apparatus according to claim 1 or 2,
The transfer means includes a transfer roller that forms a transfer nip between the latent image carrier covering film and the latent image carrier.
The latent image carrier-coated film and the recording medium enter the entrance side of the transfer nip, respectively, and the recording medium abuts the latent image carrier through the latent image carrier-coated film at the transfer nip. An image forming apparatus, wherein the latent image carrier-covered film is separated from the latent image carrier together with the recording medium on the exit side of the transfer nip. The image forming apparatus according to claim 4.
The latent image carrier covering film that has passed through the transfer nip together with the recording medium enters the fixing unit of the fixing device that heats and fixes the toner image on the recording medium together with the recording medium, and then records after passing through the fixing unit. An image forming apparatus that is separated from a medium. The image forming apparatus according to claim 5.
The fixing device includes a heating roller provided with a heat source therein, and a pressure roller that contacts and pressurizes the heating roller,
An image forming apparatus, wherein a fixing nip as the fixing portion is formed at a contact portion between the heating roller and the pressure roller. The image forming apparatus according to claim 5.
The fixing device includes a plate-shaped heating body that faces the latent image carrier-covered film at the fixing portion and extends in a direction orthogonal to the moving direction of the latent image carrier-covered film. Image forming apparatus. The image forming apparatus according to any one of claims 5 to 7,
A film that cools the latent image carrier covering film downstream of the fixing unit in the moving direction of the latent image carrier covering film and upstream of a position where the latent image carrier covering film is separated from the recording medium. An image forming apparatus having a cooling unit. The image forming apparatus according to any one of claims 1 to 8,
Film cleaning for removing foreign matter on the surface of the latent image carrier covering film after the latent image carrier covering film is separated from the surface of the latent image carrier and before being wound around the surface of the latent image carrier again An image forming apparatus comprising: means. The image forming apparatus according to any one of claims 1 to 9,
After the latent image carrier-coated film is separated from the surface of the latent image carrier, the charging polarity of the toner existing on the surface of the latent image carrier-coated film until it is wound around the latent image carrier surface again. An image forming apparatus comprising: a polarity control unit that aligns a predetermined charge polarity. The image forming apparatus according to claim 10.
The image forming apparatus according to claim 1, wherein the polarity control means includes a brush roller-shaped polarity control brush to which a voltage having the same polarity as that of toner used in toner image formation is applied. The image forming apparatus according to claim 10.
The charging means includes a roller-shaped charging roller,
The polarity control means includes a roller-shaped polarity control roller to which a voltage having the same polarity as the toner used in toner image formation is applied,
An image forming apparatus, wherein the charging roller and the polarity control roller are a common roller member. The image forming apparatus according to claim 10 or 12,
The position of the toner image formation on the downstream side of the moving direction of the latent image carrier covering film from the position where the polarity control means aligns the charging polarity of the toner existing on the surface of the latent image carrier covering film with a predetermined charging polarity. And an on-film toner collecting means for collecting toner having a predetermined charging polarity on the upstream side of the moving direction of the latent image carrier-covered film. The image forming apparatus according to claim 13.
The on-film toner collecting means is arranged to face the latent image carrier covered with the latent image carrier coating film on the upstream side of the surface movement direction of the latent image carrier with respect to the toner image forming position. A rotatable sleeve member disposed in a developing device which is a toner image forming unit;
A magnet roller disposed inside the sleeve member and provided with a plurality of magnetic poles;
An image forming apparatus comprising: a voltage applying unit that applies a voltage having a polarity opposite to the predetermined charging polarity to the sleeve member. The image forming apparatus according to claim 14.
The surface movement direction of the sleeve member at a position facing the latent image carrier covered with the latent image carrier coating film is opposite to the surface movement direction of the latent image carrier coating film. An image forming apparatus, wherein the sleeve member rotates so as to become

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