JP4139060B2 - Image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer, and more particularly to an image forming apparatus having a rotating body used for image formation.
[0002]
[Prior art]
In this type of image forming apparatus, generally, a toner image formed on a surface of an image carrier formed in a drum shape or a belt shape as the rotating body by a well-known image forming process using an electrophotographic method. Is transferred, and a transfer material such as an OHP sheet or copy paper is fed to a transfer portion between the image carrier and a transfer means such as a transfer charger or a transfer roller to which a predetermined transfer bias is applied. The toner image is transferred onto the transfer material by the transfer means. Then, after the transfer material onto which the toner image has been transferred is separated from the image carrier, the toner image is fixed at a fixing portion between a fixing roller as a fixing unit and a press roller.
[0003]
By the way, the transfer material onto which the toner image has been transferred is likely to be electrostatically attracted to the image carrier, so that the transfer material is not separated from the image carrier, and there is a risk of poor transfer material separation. For this reason, in this type of image forming apparatus, there is known an apparatus in which a separating means is arranged at a separation portion downstream of the transfer portion so that the transfer material is forcibly separated from the image carrier. .
[0004]
[Problems to be solved by the invention]
The present inventor previously disclosed that the separation means uses two separation claws provided so that the tip portion contacts the image carrier (see Japanese Patent Application No. 2000-207275). In this image forming apparatus, both ends of the transfer material in the longitudinal direction of the image carrier are forcibly separated by the separation claw.
[0005]
However, even in an image forming apparatus equipped with such a separating means, when a thin transfer material is used, the transfer material itself is weak, so that transfer material separation failure occurs, and the fixing portion In some cases, the transfer material does not smoothly enter and the transfer material is wrinkled or jammed. Specifically, with the central portion of the transfer material in the longitudinal direction of the image carrier being electrostatically attracted to the image carrier, only both ends of the transfer material in the longitudinal direction are forcibly separated from the image carrier. As a result, the transfer material is curved. Then, when the transfer material in the curved state enters the fixing portion as it is, the transfer material becomes wrinkled or a jam occurs.
[0006]
The image forming apparatus is not limited to the image forming apparatus provided with the separating unit, and the longitudinal direction of the rotating body is also used in the image forming apparatus in which the transferring material is separated from the rotating body using, for example, the stiffness and weight of the transferring material itself. In the state in which the central portion of the transfer material is electrostatically attracted to the rotating body, only both ends of the transfer material in the longitudinal direction are separated from the rotating body, and the transfer material may be curved. Therefore, even in an image forming apparatus that does not include a separating unit, there is a risk that wrinkles or jams of the transfer material may occur similarly due to the curvature of the transfer material.
[0007]
The present invention has been made in view of the above problems, and the object of the present invention is to reduce the bending of the transfer material due to the electrostatic attraction force with the rotating body, and to prevent the transfer material from wrinkling and jamming. An object of the present invention is to provide an image forming apparatus that can be suppressed.
[0008]
[Means for Solving the Problems]
To achieve the above object, a first aspect of the invention, among the plurality of transport guides, each pair of conveyance guides on the corresponding positions at both ends in the longitudinal direction of the transfer material standard size, an auxiliary member for protruding the rotary section than other transport guides the pair, the attachment means for attaching the transfer material detachably and separation member for separating from the rotating member is provided, a plurality of the pair The auxiliary member and the separating member are attached to the at least one of the plurality of pairs by the attaching means .
According to a second aspect of the present invention, in the image forming apparatus of the first aspect, the opening / closing cover that can be opened and closed with respect to the main body case is provided with the plurality of conveyance guides.
The invention of claim 3 is the image forming apparatus according to claim 2, respectively both ends in the longitudinal direction of the transfer material being conveyed, it has to pass between the auxiliary member and the separating member It is characterized by.
[0009]
In this image forming apparatus, among the plurality of conveyance guides , a conveyance guide located at a position corresponding to an end portion in the longitudinal direction of the rotator of a standard size transfer material is moved closer to the rotator than the other conveyance guides by an auxiliary member. The projecting portion is pushed, and both end portions in the longitudinal direction of the transfer material are pushed out toward the rotating body by the projecting portion , and the transfer material is guided to the next process while restricting the curvature of the transfer material. Thereby, the curve of the transfer material due to the electrostatic attraction force with the rotating body can be reduced, and the generation of wrinkles and jams on the transfer material can be suppressed.
[0011]
In this image forming apparatus, an auxiliary member configured to be detachable from the transport guide is attached to a desired transport guide in accordance with the width of the transfer material used in the longitudinal direction of the rotating body. For transfer materials of various widths, it is possible to reduce the curvature of the transfer material due to electrostatic attraction with the rotating body.
In addition, by configuring the auxiliary member so that it can be attached to and detached from the transport guide plate, only transfer materials that do not easily cause bending of the transfer material due to electrostatic attraction with the rotating body, such as strong transfer materials, are used. It is possible to provide a user with a low initial cost without providing the auxiliary member. Furthermore, when an auxiliary member is required, it can be retrofitted as an option.
[0013]
In this image forming apparatus, the transfer material is separated from the rotating body at the tip of the separation claw. A separation claw detachable from the conveyance guide is attached to a desired conveyance guide in accordance with the width of the transfer material used in the longitudinal direction of the rotating body, so that various sizes of the transfer material can be well separated. can do.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment in which the present invention is applied to a printer which is an image forming apparatus using an electrophotographic process will be described. First, the outline of the entire apparatus will be described with reference to FIGS. 1 and 2.
The printer 200 includes a drum-shaped photosensitive member 1 as an image carrier that is a rotating member used in an image forming apparatus, a charging roller 2 as a charging unit, a developing unit 3 as a developing unit, and a cleaning unit as a photosensitive member cleaning unit. 4 includes an image forming unit 100 configured to be detachable from the main body of the printer 200 that accommodates 4 (see FIG. 2).
[0015]
A latent image writing unit 6 for writing an electrostatic latent image on the photoreceptor 1 is provided on the side of the image forming unit 100. As this latent image writing unit 6, for example, an optical signal corresponding to image information read by a scanner or the like is emitted from a semiconductor laser, and the laser beam is scanned by a polygon mirror that is driven to rotate. A device for writing an optical signal 6a corresponding to color-separated image information on a photosensitive member through a converging lens and a mirror for correcting surface tilt of a polygon mirror disposed in the optical path, a mirror for deflecting laser light, or the like is used. be able to.
[0016]
Also, below the image forming unit 100, a transfer roller 8 for separating and feeding transfer sheets 8 as transfer materials stored in a sheet feed cassette 7 one by one, and a sheet feed roller 9 feeds the sheet. After the transferred transfer paper 8 is temporarily kept in front of the photoreceptor 1, the leading edge of the image formed on the photosensitive body 1 and the leading edge of the transfer paper 8 serve as the photosensitive body 1 and a transfer unit. A registration roller 11 is provided for re-feeding the transfer paper 8 in synchronism with the rotation of the photoconductor 1 at the timing when the nip portion with the transfer roller 10 is reached almost simultaneously.
[0017]
Further, above the image forming unit 100, there are a fixing roller 14 and a press roller 15 containing a heater 13 rotatably arranged so as to be pressed against each other across the conveyance path 12 of the transfer paper 8. A fixing device 16 is provided. In addition, on the downstream side of the fixing device 16 in the transfer paper conveyance direction, the transfer paper 8 that has passed through the nip between the fixing roller 14 and the press roller 15 is discharged on the upper side of the main body case 200 a of the printer 200. A paper discharge roller 18 for discharging the paper to the stacker unit 17 is provided.
[0018]
Also, in the main body case 200a of the printer 200, an electrical unit 20 is provided as a control means for controlling each image forming means and print information related to the image forming process of the printer 200. The electrical unit 20 includes a control board (not shown) and various adjustment switches and control units mounted on the control board, and is arranged from the side to the lower side of the latent image writing unit 6. It is housed in an electrical case 21 made of metal.
[0019]
In the printer 200 having such a configuration, first, the photosensitive member 1 is uniformly charged by the charge from the charging roller 2 during rotation. Next, the latent image writing unit 6 is driven based on image information read from the outside, whereby the image information is formed as an electrostatic latent image in the charging area (image forming area) of the photoreceptor 1. The The electrostatic latent image formed on the photosensitive member 1 is developed with a developer (toner) supplied to the photosensitive member 1 by the developing roller 3a of the developing unit 3 to become a visible image (toner image).
[0020]
On the other hand, while the toner image is being formed on the photosensitive member 1, the transfer paper 8 is pulled out from the paper supply cassette 7 by the paper supply roller 9, and the leading end of the transfer paper 8 is in the nip of the registration roller 11. The transfer paper 8 is put on standby in a state where it is in contact with the portion. The transfer paper 8 starts rotating with the registration roller 11 in synchronization with the rotation of the photosensitive member 1 at the timing when the leading end of the transfer paper 8 and the leading end of the toner image coincide with each other. The photosensitive member 1 is conveyed to a transfer position formed at a nip with a transfer roller 10 that is pressed against and rotated. As a result, the transfer paper 8 on which the toner image on the photosensitive member 1 is transferred at the transfer position is fixed in the process of being conveyed by the fixing roller 14 and the press roller 15 of the fixing device 16 and discharged. The paper is discharged onto the stacker unit 17 by the roller 18. In the meantime, the residual toner remaining on the photosensitive member 1 without being transferred onto the transfer paper 8 in the transfer process of the toner image onto the transfer paper 8 is transferred to the photosensitive member 1 by the cleaning blade 4a of the cleaning unit 4. It is removed from above and collected in the cleaning container 4b.
[0021]
Further, the charge on the transfer paper 8 is removed by a static elimination brush 22 as a static elimination means disposed on the downstream side of the transfer roller 10 in the transfer paper conveyance direction.
Further, the printer 200 according to the present embodiment is provided with a separation claw 203 as a separation unit that separates the transfer paper 8 from the photoconductor, and the transfer paper 8 that has been neutralized by the static elimination brush 22 is physically removed from the photoconductor 1. To separate. The separation means using the separation claw 203 will be described in detail later.
[0022]
On the other hand, the main body case 200a of the printer 200 includes an open / close cover structure 201 that forms a side surface of the main body case 200a on the transfer path 8 side of the transfer paper 8 and a manual feed unit 23 for manually feeding the transfer paper. Are supported by the same support shaft 202. This manual feed unit 23 is configured to be able to take the open position shown in FIG. 1 and the closed position (see FIG. 2) stored in the manual feed unit storage portion 201c which is a recess of the opening / closing cover structure 201. ing. The transfer paper fed using the manual feed unit 23 is conveyed to the registration roller 11 by the rotation of the manual paper feed roller 24 provided on the printer main body 200 side.
[0023]
Further, as shown in FIG. 3, a holder portion 201 b that holds the transfer roller 10 is fixed to the opening / closing cover structure 201, so that the transfer roller 10 is supported by the opening / closing cover structure 201. . Further, the static elimination brush 22 is also attached to the opening / closing cover structure 201.
[0024]
Further, the opening / closing cover structure 201 is provided with a conveyance guide plate 201 a for forming a transfer sheet conveyance surface of the conveyance path 12 and guiding the transfer sheet 8 to the fixing device 16. The conveyance guide plate 201a will also be described in detail later.
[0025]
In FIG. 1, when the opening / closing cover structure 201 is opened in the clockwise direction in the drawing with the support shaft 202 as the center of rotation, as shown in FIG. 2, the conveyance guide plate 201a, the transfer roller 10, and the charge eliminating brush 22 are shown. However, the transfer paper 8 is largely retracted from the conveyance path 12. Therefore, operations such as attachment / detachment of the image forming unit 100 to / from the printer body, replacement of the fixing device 16, and jam processing of the transfer paper 8 jammed in the transport path 12 can be easily performed.
[0026]
Next, the separation unit and the conveyance guide plate 201a, which are features of the present embodiment, will be described.
FIG. 3 is an explanatory diagram illustrating a schematic configuration of the separating unit, and FIG. 4 is a perspective view of the separating unit. The separation means is configured using a separation claw 203 made of a sheet-like member and a support member 202 that supports the separation claw 203. The separation claw 203 is bent toward the photoreceptor as shown in FIG. 3 in the vicinity of the photoreceptor 1, and the tip thereof is processed at an acute angle as shown in FIG. The separation claw 203 is supported at the base end portion by the support member 203 so that the tip end portion thereof can come into contact with the surface of the photoreceptor 1. The separation claw 203 and the support member 202 are provided on the two conveyance guide plates 201a at both ends in the longitudinal direction of the photosensitive member 1 in the conveyance guide plate 201a (see FIG. 5). In this embodiment, the support member 202 is attached to the conveyance guide plate 201a with a double-sided tape.
[0027]
The material of the separation claw 203 is preferably such that at least the contact portion with the photoconductor is elastic so that the surface of the photoconductor 1 is not damaged by contact with the separation claw 201. In this embodiment, a sheet-like member made of a PET (polyethylene terephthalate) film having a thickness of 0.125 mm is used as the separation claw 203. Further, as the support member 202, a SUS material having a thickness of 1 mm is used.
[0028]
Further, as shown in FIG. 5, a plurality of conveyance guide plates 201 a are arranged along the longitudinal direction of the photosensitive member 1 so as to protrude from the conveyance path 12 so as to guide the transfer paper 8 at the end face. In this embodiment, the conveyance guide plate 201a is formed as an integral part with the opening / closing cover structure 201 to reduce the number of components of the printer, but is formed as a separate member and attached to the opening / closing cover structure 201. May be. For example, if the conveyance guide plate 201a is formed using a conductive member having a medium resistance, toner dust in an unfixed image is suppressed and a higher quality image can be obtained.
[0029]
In this embodiment, as shown in FIG. 5, auxiliary plates 204 as auxiliary members are attached to the two conveyance guide plates 201a at both ends in the longitudinal direction of the photoreceptor 1 among the conveyance guide plates 201a. As a result, the transfer paper 8 is protruded closer to the rotating body than the other conveyance guide plate 201a so as to regulate the curvature of the transfer paper 8 due to the electrostatic attraction force with the photoconductor 1. Specifically, as shown in FIG. 4, a through hole 205 is provided in the auxiliary plate 204 and the support member 202 integrated with, for example, a double-sided tape, and the through hole 205 and the illustration provided in the conveyance guide plate 201 a The auxiliary plate 204 is attached to the conveyance guide plate 201 by engaging the screw hole that is not to be engaged and screwing.
[0030]
In the above configuration, the central portion of the transfer paper 8 on which the toner image is transferred is lifted by the electrostatic attraction force with the photosensitive member 1 as shown in FIG. When the transfer sheet 8 is separated and reaches the conveyance guide plate 201a, the both end portions of the transfer sheet 8 are placed on the photosensitive member 1 side at the end surfaces of the conveyance guide plates 201a at the both end portions which are protruded highly by attaching the auxiliary plate 204. The transfer paper 8 is guided to the fixing device 16 while the extrusion and the lifting of the transfer paper 8 are restricted.
[0031]
In the above configuration, the amount of curve h of the transfer paper 8 when using the thin transfer paper 8 that is likely to be curved due to the electrostatic attraction force with the photoreceptor 1 is shown in FIG. The bending amount h1 when the plate 204 is not provided can be made smaller. Since the transfer paper 8 enters the fixing nip formed by the fixing roller 14 and the press roller 15 in a state where the curvature of the transfer paper 8 is reduced as described above, the transfer paper 8 is not wrinkled or jammed at the fixing nip. Can be suppressed.
[0032]
In the present embodiment, the curvature of the transfer paper 8 can be reduced even for various transfer papers 8 having different widths in the longitudinal direction of the photoconductor 1, and the transfer paper 8 can be satisfactorily separated from the photoconductor 1. Such a configuration is adopted. Hereinafter, such a configuration will be described.
As shown in FIG. 5, in this embodiment, each set is different with two conveyance guide plates 201 a located at left and right symmetrical positions with respect to the central portion in the longitudinal direction of the photosensitive member of the conveyance guide plate 201 a as one set. This corresponds to the transfer paper 8 having a width. Each conveyance guide plate 201a is arranged such that the distance between each pair of conveyance guide plates 201a is several mm smaller than the width of the corresponding transfer paper 8. Each conveyance guide plate 201 a is provided with a screw hole (not shown). The auxiliary plate 204 is engaged with the through hole 205 provided in the auxiliary plate 204 and the support member 202 to be screwed. And the support member 202 is attached. That is, the auxiliary plate 204 and the separation claw 203 attached to the auxiliary plate 204 via the support plate 202 are configured to be detachable from the respective transport guide plates 201a.
[0033]
In the above configuration, the auxiliary plate 204 and the support plate 202, by mounting the pair of sheet guide 201a corresponding to the width of the transfer sheet 8 to be used also for various transfer sheet 8 different widths, The curvature of the transfer paper 8 can be reduced, and the transfer paper 8 can be satisfactorily separated from the photoreceptor 1.
In addition, since the separation claw 203 and the auxiliary plate 204 can be attached to and detached from the conveyance guide plate 201a, the separation claw 203 and the auxiliary plate 204 are attached to cope with a change in the size of the transfer material to be used. It is also possible to improve handling when changing the conveyance guide plate.
Further, for example, for a user who does not use a thin transfer material, it is possible to provide an apparatus with low initial cost that does not include the auxiliary plate 204 and the separation claw 203. Furthermore, when the auxiliary plate 204 or the separation claw 203 is necessary, it can be retrofitted as an option.
[0034]
【The invention's effect】
According to the first to third aspects of the present invention, it is possible to reduce the bending of the transfer material due to the electrostatic attraction force with the rotating body, and it is possible to suppress the occurrence of wrinkles and jams on the transfer material. is there.
[0035]
In addition, the transfer material having various widths also has an excellent effect of being able to reduce the curvature of the transfer material due to the electrostatic adsorption force with the rotating body.
[0036]
Furthermore , there is an excellent effect that transfer materials of various sizes can be well separated.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram illustrating an entire printer according to an embodiment.
FIG. 2 is a schematic configuration diagram illustrating a state where an opening / closing cover of the printer is opened.
FIG. 3 is an explanatory diagram illustrating a schematic configuration of a separating unit.
FIG. 4 is a perspective view of the separation means.
FIG. 5 is a side view of a separating unit and a conveyance guide plate as viewed from a transfer material conveyance direction.
FIG. 6 is an explanatory diagram for explaining a defect of a conveyance guide plate according to a comparative example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging roller 3 Developing unit 4 Cleaning unit 8 Transfer paper 10 Transfer roller 12 Transfer paper transport path 14 Fixing roller 15 Press roller 16 Fixing device 22 Static elimination brush 100 Process cartridge 200 Printer 200a Printer main body case 201 Opening / closing cover 201a Transport Guide plate 202 Support member 203 Separation claw 204 Auxiliary plate 205 Through hole

Claims (3)

An image having a rotator used for image formation and a plurality of conveyance guides arranged along the longitudinal direction of the rotator so as to guide the separated transfer material to the next process at the end face protruding in the transfer material conveyance path. In the forming device,
Among the plurality of transport guides, each pair of conveyance guides on the corresponding positions at both ends in the longitudinal direction of the transfer material standard size, for protruding the said pair in the rotational body side than the other conveying guide Mounting means for detachably mounting the auxiliary member and the separating member for separating the transfer material from the rotating body , a plurality of the pairs corresponding to a plurality of fixed sizes, and a plurality of the plurality of pairs An image forming apparatus , wherein the auxiliary member and the separating member are attached to at least one of the pair by the attaching means . The image forming apparatus according to claim 1.
An image forming apparatus, comprising: an opening / closing cover that is openable / closable with respect to the main body case; The image forming apparatus according to claim 2.
Each of both ends in the longitudinal direction of the transfer material being conveyed, the image forming apparatus is characterized in that as passage between the auxiliary member and the separating member.

Images