JP2003057956A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device capable of preventing the defect of image quality such as the flowing of a toner image (stripe-shaped void) from occurring at a transfer point by stabilizing a discharge state in the axial direction of the leading edge of a destaticizing member. SOLUTION: In this image forming device, a plurality of toner images formed on an image carrier are temporarily multiply primarily transferred to an intermediate transfer body, and then a plurality of toner images multiply transferred to the intermediate transfer body are collectively secondarily transferred to transfer material to form an image. The conductive destaticizing member for destaticizing the intermediate transfer body and the transfer material is arranged on the downstream side of the secondary transfer part of the intermediate transfer body, and the back side of the destaticizing member is held by an insulating housing member so as to bring the whole leading edge of the destaticizing member into contact with the surface of the housing member.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus, such as a copying machine, a printer, or a facsimile, which employs an electrophotographic system, and more particularly, a charge removing member is provided downstream of a transfer point to separate and run a transfer material. The present invention relates to an improvement in an image forming apparatus configured to stabilize the state.

[0002]

2. Description of the Related Art Conventionally, various types of image forming apparatuses, such as copying machines, printers, and facsimiles, which have adopted the electrophotographic method have been proposed and have been actually commercialized. Among such image forming apparatuses,
As an image forming apparatus capable of forming a high-quality color image regardless of the material of the transfer material, the photosensitive drum is
Each time it rotates, four color toner images of yellow, magenta, cyan, black, etc. are sequentially formed on the photosensitive drum, and four toner images of yellow, magenta, cyan, black, etc. are sequentially formed on this photosensitive drum. A color toner image is temporarily transferred onto the intermediate transfer member by the primary transfer rolls in a multiplex manner, and then the secondary transfer rolls are collectively transferred from the intermediate transfer member onto the transfer material to form a color image. Various 4-cycle intermediate transfer type image forming apparatuses for forming have been proposed and have been commercialized by the present applicants.

In the four-cycle intermediate transfer type image forming apparatus, yellow, which is sequentially formed on the photosensitive drum,
Toner images of four colors, such as magenta, cyan, and black, are temporarily primary-transferred on the intermediate transfer member by the primary transfer roll, so that the intermediate transfer member sequentially transfers the toner images of the respective colors from the photosensitive drum. In addition, the intermediate transfer member itself may be charged to a high potential by being charged by the primary transfer roll for transfer. Therefore, in the above-mentioned image forming apparatus, when the transfer material to which the toner images of four colors such as yellow, magenta, cyan, and black are collectively secondarily transferred is peeled from the intermediate transfer body, the transfer material is transferred onto the transfer material by peeling discharge. The toner image secondarily transferred onto the intermediate transfer member may be disturbed, or in some cases, the transfer material is not peeled off from the intermediate transfer member but is conveyed while being adsorbed on the intermediate transfer member, which may cause a jam. Was there.

Therefore, in the above-mentioned image forming apparatus, a charge removing member such as a charge removing needle or a sawtooth charge removing plate is provided downstream of the secondary transfer point, and a bias voltage is applied to the charge removing member to transfer the intermediate transfer member and the transfer material. It is configured to stabilize the peeling and running state of the transfer material by removing the charge.

[0005]

However, the above-mentioned prior art has the following problems. That is, in the case of the above-mentioned conventional image forming apparatus, when spherical toner is used as the toner for forming the toner image, the transfer efficiency of the toner image is raised and the image quality is improved. However, there is a problem in that the flow of the toner image on the transfer material (white streaks in the form of streaks) occurs in the charge eliminating section. One of the reasons why the toner image flow (streak-shaped white spots) occurs is the shape of the toner. If spherical toner is used as the toner for forming the toner image in order to improve the image quality by increasing the transfer efficiency of the toner image, the spherical toner easily rolls due to its shape, and unevenness in the electric field for static elimination by the static eliminating member is uneven. If there is, it is easy to move depending on the strength of the static elimination electric field, and a toner image flow (streak-shaped white spots) occurs. This toner image flow (streak-shaped white spots) remarkably occurs in the spherical toner, and tends to improve as the toner shape gradually changes from a spherical shape to an elliptical shape.

Further, in the static elimination member such as the static elimination needle or the sawtooth static elimination plate, if the positional accuracy of the tip of the static elimination member, that is, the gap between the tip of the static elimination member and the housing supporting the static elimination member varies, Since the discharge state at the tip of the static eliminator changes along the axial direction (longitudinal direction), the toner is affected by the unevenness of the discharge state, and a toner image flow (white streaks) occurs. It had a problem that it would end up.

Therefore, the present invention has been made in order to solve the above-mentioned problems of the prior art, and the purpose thereof is to stabilize the discharge state along the axial direction of the tip of the static eliminating member. An object of the present invention is to provide an image forming apparatus that does not cause an image quality defect such as a toner image flow (striped white spots) at a transfer point.

[0008]

In order to solve the above-mentioned problems, according to the invention described in claim 1, a plurality of toner images formed on an image bearing member are temporarily primary-transferred in multiple layers onto an intermediate transfer member. After that, in the image forming apparatus for forming an image by collectively secondary-transferring a plurality of toner images transferred on the intermediate transfer member onto the transfer material, the secondary transfer of the intermediate transfer member is performed. On the downstream side of the section, a conductive charge removing member for removing charge from the intermediate transfer member and the transfer material is arranged,
The back side of the static eliminator is held by an insulating housing member, and all the tips of the static eliminator are brought into contact with the surface of the housing member.

According to the invention described in claim 1, since all the tips of the static eliminating member are configured to contact the surface of the housing member, the discharging state of the tip of the static eliminating member can be stabilized, and the static eliminating member concerned. It is possible to prevent the discharge state from fluctuating along the axial direction of the toner, and even in the case of turbulent toner such as spherical toner, image quality defects such as toner image flow (striped white spots) occur. Can be prevented.

Further, the invention according to claim 2 is configured such that the static eliminating member is bent at its distal end so that all the distal ends of the static eliminating member come into contact with the surface of the housing member.

Further, according to a third aspect of the present invention, by biasing the tip of the static eliminating member by the biasing means so as to contact the surface of the housing member, all the tips of the static eliminating member are stored in the housing. It is configured to contact the surface of the member.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

Embodiment 1 FIG. 2 shows a digital full-color copying machine as an image forming apparatus according to Embodiment 1 of the present invention. It is needless to say that the image forming apparatus may be a printer, a facsimile or the like other than the copying machine.

In FIG. 2, reference numeral 1 denotes a main body of a digital full-color copying machine, and an IIT 2 for reading an image of an original having a color image or the like is provided on an upper portion of the main body (image forming apparatus main body) 1 of the digital full-color copying machine. (Ima
ge Input Terminal). Image data read by this IIT2,
Image data sent from a personal computer (not shown) is, for example, red (R), green (G), blue (B).
Image data of three colors (each of 8 bits) is sent to an image processing device (not shown), and in this image processing device, shading correction, positional deviation correction, lightness / color space conversion, gamma correction, and frame correction are performed on the image data. Predetermined image processing such as erasing and color / moving editing is performed.

The image data subjected to the predetermined image processing by the image processing apparatus as described above is yellow (Y), magenta (M), cyan (C), black (BK) (each 8).
ROS3 (Rast) as four-color image data of
ER Output Scanner), and the ROS 3 performs image exposure with the laser beam LB according to the image data.

The photosensitive drum 4 as an image bearing member, which is scanned and exposed with the laser beam LB by the ROS 3, is rotationally driven at a predetermined speed in the arrow direction by a driving means (not shown). This photosensitive drum 4
The surface of is charged in advance with a predetermined polarity (for example, a negative polarity) and a potential by a scorotron 5 for primary charging, and then a laser beam LB is scanned and exposed according to image data to form an electrostatic latent image. To be done. The electrostatic latent image formed on the photoconductor drum 4 includes four color developing devices 6Y, 6M, 6C and 6BK of yellow (Y), magenta (M), cyan (C) and black (BK). By the rotary type developing device 6, for example, reversal development is performed with the toner charged to the negative polarity which is the same polarity as the charging polarity of the photoconductor drum 4 to form a toner image of a predetermined color. The toner image formed on the photosensitive drum 4 is charged by a pre-transfer charger (not shown) as necessary, and the charge amount is adjusted.

In the digital full-color copying machine according to the present embodiment, by improving the transferability of the toner image and the like, it is possible to further improve the image quality and to eliminate oil in the fixing device. In 6M, 6C, and 6BK, instead of the amorphous toner produced by the conventional pulverization method or the like, a nearly spherical toner is used.

Specifically, the toner has an average particle size of 6
In order to improve toner graininess and obtain high transferability,
A spherical toner having a shape factor (ML ² / A) of 110 to 140 or less, and a shape factor of 120 (here, a polymerized toner) is used. An external additive is added to the spherical toner for cleaning property, transfer property and charge maintaining property. Further, the developing devices 6Y, 6M, 6C and 6BK use a two-component developer, and the toner volume (Tv) in this two-component developer is 30 or more.

The shape factor of the toner (ML ² /
A) is represented by the following equation. Shape factor (ML ² / A) = (absolute maximum length of toner diameter) ²
/ (Projected area of toner) x π / 4 x 100

The toner images of the respective colors sequentially formed on the photosensitive drum 4 are provided on the intermediate transfer belt 7 as an intermediate transfer body disposed below the photosensitive drum 4 as a first transfer means. The images are sequentially transferred by the primary transfer roll 8 in a state of being superimposed on each other. This intermediate transfer belt 7
Is driven by a drive roll 9, a tension roll 10, a backup roll 11 and a driven roll 12 as opposed rolls forming a part of the secondary transfer means, for example, at the same moving speed as the peripheral speed of the photosensitive drum 4 in the arrow direction. It is rotatably supported along. In addition, the intermediate transfer belt 7
Together with a drive roll 9, a tension roll 10, a backup roll 11, and a driven roll 12 that stretch the intermediate transfer belt 7, the intermediate transfer belt unit is integrally formed. It is attachable to and detachable from the main body 1 in the direction of insertion and removal on the front side.

On the intermediate transfer belt 7, yellow (Y), magenta (M), cyan (C), and black (BK), which are formed on the photosensitive drum 4, are formed according to the color of the image to be formed. Toner images of all or part of the four colors are transferred in a state of being sequentially superposed by a primary transfer roll 8 as a primary transfer unit. The toner image transferred onto the intermediate transfer belt 7 is transferred onto a secondary transfer position at a predetermined timing, and a backup roll 11 that supports the intermediate transfer belt 7 on a transfer sheet 13 as a transfer material.
Transfer is performed by the pressure contact force and the electrostatic attraction force of the secondary transfer roll 14 that constitutes a part of the secondary transfer unit that is pressed against the backup roll 11. As shown in FIG. 2, the transfer sheet 13 is of a predetermined size from a plurality of sheet cassettes 15, 16 and 17 arranged in the lower part of the copying machine body 1 by a feed roll 18 and a separation roll pair 19. Papers are fed one by one. The transferred transfer paper 13 is transferred by the plurality of transport roll pairs 20 and the registration rolls 21.
The intermediate transfer belt 7 is conveyed to a secondary transfer position at a predetermined timing. Then, on the transfer paper 13, as described above, the backup roll 1 as the secondary transfer means is provided.
1 and the secondary transfer roll 14, the intermediate transfer belt 7
Toner images of a predetermined color are collectively transferred from above.

The transfer paper 13 on which the toner image of a predetermined color has been transferred from the intermediate transfer belt 7 is neutralized together with the intermediate transfer belt 7 by the neutralization device 40, and separated from the intermediate transfer belt 7, as will be described later. After that, the toner image is conveyed by the suction conveyance belt 22 to the fixing device 23 as a fixing means, and the heating roller 24 and the pressure roller 25 of the fixing device 23 fix the toner image on the recording paper 13 by heat and pressure. The sheet is discharged onto the sheet discharge tray 27 provided outside the copying machine main body 1 by the main body discharge roll 26, and the color image forming process is completed.

In FIG. 2, 28 is a cleaning device for the photoconductor for removing residual toner, paper dust and the like from the surface of the photoconductor drum 4 after the transfer process is completed, and 29 is the intermediate transfer belt 7. A cleaning device for cleaning the intermediate transfer belt for cleaning, 30 is a cleaner for cleaning the secondary transfer roll 14, and 31 is a manual feed tray. The toner collected by the cleaning device 28 for the photoconductor and the cleaning device 29 for the intermediate transfer belt is collected and collected in the collected toner box 32.

By the way, in this embodiment, a plurality of toner images formed on the image bearing member are temporarily primary-transferred to the intermediate transfer member in a multiple manner, and then a plurality of toner images are transferred to the intermediate transfer member in a multiple manner. In an image forming apparatus that forms an image by collectively secondarily transferring the toner image of the intermediate transfer member onto a transfer material, a charge removal of the intermediate transfer member and the transfer material is performed downstream of the secondary transfer portion of the intermediate transfer member. Is arranged so that the back side of the static elimination member is held by an insulating housing member, and all the tips of the static elimination member are brought into contact with the surface of the housing member.

Further, in this embodiment, the static elimination member is
By bending the tip, all the tips of the charge eliminating member are configured to contact the surface of the housing member.

That is, in this embodiment, as shown in FIGS. 2 and 3, the secondary transfer roll 14 is pressed against the backup roll 11 which stretches the intermediate transfer belt 7 via the intermediate transfer belt 7. On the downstream side of the next transfer section 41,
A static eliminator 40 is arranged at a position close to the surface of the secondary transfer roll 14 below the transfer material transport path through which the transfer material 13 separated by the secondary transfer portion 41 passes.
In FIG. 3, reference numeral 35 denotes a suction conveyance belt 22 for the transfer material 13.
The guide member which guides to is shown.

As shown in FIGS. 4 and 5, the static eliminator 40 is a conductive static eliminator 42 for neutralizing the intermediate transfer belt 7 and the transfer material 13, and an insulator for holding the rear side of the static eliminator 42. And a flexible housing member 43. As shown in FIG. 4, the conductive static eliminating member 42 is formed of a conductive thin plate member made of stainless steel or the like, and the distal end portion 42 a of the static eliminating member 42 is formed.
Are formed in a sawtooth shape at a constant pitch. In addition, the conductive static elimination member 42 has a hole 44 for positioning and fixing.
Are drilled. The tip portion 42a of the static elimination member 42 is not limited to the sawtooth shape and may be formed in a needle shape.

On the other hand, as shown in FIGS. 1 and 5, the housing member 43 is made of an insulating material such as synthetic resin, and its tip portion 43a is transferred from the intermediate transfer belt 7 by transfer. An inclined surface is formed so as to guide the material 13. Further, one side surface 43b (right side surface in the drawing) of the housing member 43 constitutes a flat surface for disposing the static eliminator 42, and the flat surface 43b for disposing the static eliminator is shown in FIG. As described above, the thin plate static eliminating member 42 is attached in a state where the positioning fixing hole 44 is fitted to the projection 45 projecting at a predetermined position of the plane surface 43b. Further, a cover 46 for the charge removing member for holding and fixing the charge removing member 42 is attached to the front surface (the surface on the charge removing member side) of the housing member 43. In addition, the transfer material 1 separated from the intermediate transfer belt 7 has a tip portion on the flat surface 43b for disposing the charge removing member.
A convex portion 47 having a triangular cross section which forms a slope for guiding
Is provided so as to form the same plane as the slope 43a, and the space between the convex portions 47 is shown in FIG.
As shown in, a recess 48 in which the tip portion 42a of the static elimination member 42 is located is provided.

By the way, as shown in FIG. 1, the static elimination member 42 has a tip 42b bent toward the housing member 43, and all the tips 42 of the static elimination member 42 are bent.
b is a flat surface 43b for disposing the static elimination member of the housing member 43
It is configured to contact (close contact) with. Further, the tip end 42b of the static eliminating member 42 is arranged so as to be located below the upper end of the housing member 43 by a predetermined amount. A predetermined voltage is applied to the static elimination member by a power source (not shown).

With the above-described structure, in the image forming apparatus according to the first embodiment, the discharge state along the axial direction of the tip of the charge eliminating member is stabilized in the following manner, so that the toner image is formed at the transfer point. Flow (white streaks)
It is designed to prevent the occurrence of image quality defects such as.

That is, in the digital full-color copying machine according to this embodiment, as shown in FIG. 2, yellow (Y), magenta (M), cyan (C), which are multiply transferred onto the intermediate transfer belt 7, Backup roll 1 that supports the intermediate transfer belt 7 for a toner image such as black (BK)
1 and the secondary transfer roll 14 that constitutes a part of the secondary transfer means that is in pressure contact with the backup roll 11 and the electrostatic attraction force collectively perform secondary transfer on the transfer material 13 to form a color image. It is configured to form an image.

At this time, in the digital full-color copying machine, as shown in FIG. 3, toner images of yellow (Y), magenta (M), cyan (C), black (BK), etc. are formed on the intermediate transfer belt 7. When the transfer materials 13 that have been secondarily transferred in a batch are separated from the intermediate transfer belt 7, the neutralization device 40 disposed on the downstream side of the secondary transfer portion 41 of the intermediate transfer belt 7 causes the intermediate transfer belt 7 to move. 7 and transfer material 13
Is designed to eliminate static electricity.

In the static eliminator 40, as shown in FIG. 1, the tip 42a of the static eliminator 42 is bent toward the housing member 43, and all the tips 42b of the static eliminator 42 are located in the housing member 43. It is configured to come into contact (close contact) with the flat surface 43b for disposing the charge removing member. Therefore, in the static eliminator 40, when a predetermined voltage is applied to the static eliminator 42 by a power source (not shown) and the intermediate transfer belt 7 and the transfer material 13 are neutralized by the discharge generated at the tip 42b of the static eliminator 42, the static eliminator 40 is removed. Since all the tip ends 42b of 42 are in contact with the flat surface 43b of the housing member 43 for disposing the static elimination member 42,
All the tips 42a of the above are accurately arranged geometrically at the same position with respect to the static elimination member disposing plane 43b of the housing member 43. Therefore, when a predetermined voltage is applied to the static elimination member 42 by a power source (not shown), the discharge generated at the tip 42b of the static elimination member 42 becomes uniform along the axial direction (longitudinal direction) thereof and varies along the axial direction. Does not occur. Therefore, the discharge state along the axial direction of the static elimination member tip 42b can be stabilized, and the static elimination member 4 in the secondary transfer portion 41 can be stabilized.
Since there is no variation along the axial direction in the discharge generated at the second end 42b of the second toner, a toner image is formed using a toner that easily rolls like spherical toner and is easily affected by the discharge variation in the secondary transfer portion. Even in such a case, it is possible to prevent the occurrence of image quality defects such as toner image flow (streak-shaped white spots), and it is possible to form a high quality color image.

Second Embodiment FIG. 6 shows a second embodiment of the present invention. The same parts as those of the first embodiment will be designated by the same reference numerals in the following description. The static elimination member is configured to bring all the tips of the static elimination member into contact with the surface of the housing member by urging the tip of the static elimination member into contact with the surface of the housing member by the biasing means.

That is, in the second embodiment, as shown in FIG. 6, the static elimination member 42 is disposed at a predetermined position on the static elimination member disposing plane 43b of the housing member 43 via the spacer member 50. At the same time, the tip portion 42a of the static elimination member 42 has a static elimination member cover 46 that also serves as a biasing means.
Is urged by the distal end portion 46a of the housing member 43 so as to come into contact with the static elimination member disposing flat surface 43b of the housing member 43,
All the tips 42b of the static elimination member 42 are configured to come into contact (close contact) with the surface 43b of the housing member 43.

In the second embodiment, the tip portion 42a of the static eliminating member 42 is provided with a static eliminating member cover 46 which also serves as a biasing means.
By urging the tip end portion 46a of the above, the all tip ends 42a of the static elimination member 42 can be brought into contact with the surface 43b of the housing member 43 more reliably.

The other structure and operation are the same as those in the first embodiment, and the description thereof will be omitted.

The discharge state at the tip of the static eliminating member is
Since it is easily affected by the presence or absence of a minute space between the tip of the static eliminator and the housing, as a means for stabilizing the discharge, as shown in FIG. Bending in the opposite direction so as to be separated by about 1 mm can be considered.

[0039]

As described above, according to the present invention, the discharge state along the axial direction of the tip of the charge eliminating member is stabilized, so that the toner image flows (striped white spots) or the like at the transfer point. It is possible to provide the image forming apparatus in which the image quality defect described above does not occur.

[Brief description of drawings]

FIG. 1 is a sectional configuration diagram showing a main part (B part) shown in FIG. 3 of a digital full-color copying machine as an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a digital color copying machine as an image forming apparatus according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram showing a secondary transfer unit of a digital color copying machine as an image forming apparatus according to the first embodiment of the present invention.

FIG. 4 is a front view showing a charge eliminating member.

FIG. 5 is a configuration diagram showing a main part (A part) shown in FIG. 3 of a digital full-color copying machine as an image forming apparatus according to the first embodiment of the present invention.

FIG. 6 is a sectional configuration diagram showing a main part (B part) shown in FIG. 3 of a digital full-color copying machine as an image forming apparatus according to a second embodiment of the present invention.

FIG. 7 is a cross-sectional configuration diagram showing a main portion (B portion) shown in FIG. 3 of a digital full-color copying machine as an image forming apparatus according to a reference example of the present invention.

[Explanation of symbols]

1: photoconductor drum, 7: intermediate transfer belt, 14: secondary transfer roll, 40: static eliminator, 41: secondary transfer section, 42:
Static eliminator, 42b: tip of static eliminator, 43: housing member, 43b: flat surface for arranging static eliminator.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Mikio Kobayashi             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             X Co., Ltd. (72) Inventor, Kunori Kono             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             X Co., Ltd. (72) Inventor Naoto Yoshino             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             X Co., Ltd. (72) Inventor Yukio Hayashi             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             X Co., Ltd. (72) Inventor Makoto Ochiai             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             X Co., Ltd. (72) Inventor Satoshi Matsuzaka             Fuji Zero, 2274 Hongo, Ebina City, Kanagawa Prefecture             X Co., Ltd. F-term (reference) 2H030 AA03 AD02 BB42 BB55                 2H200 FA04 FA05 GA16 GA23 GA34                       GA47 GB12 GB25 HA07 HB06                       HB31 HB45 HB46 JA02 JC04                       JC11 LA36 LC10 MA01 MA04                       MA20 MB01                 3F101 AA04 AA08 AA13 LA02 LA07                       LB03

Claims (3)

[Claims] 1. A plurality of toner images formed on an image bearing member are temporarily primary-transferred in multiple layers onto an intermediate transfer member, and then the plurality of toner images transferred in multiple layers onto the intermediate transfer member are transferred. In an image forming apparatus that forms an image by collectively secondary-transferring onto a material, a conductive charge eliminator for removing the charge of the intermediate transfer body and the transfer material is provided downstream of the secondary transfer portion of the intermediate transfer body. An image forming apparatus, wherein members are arranged, the back side of the charge removing member is held by an insulating housing member, and all the tips of the charge removing member are brought into contact with the surface of the housing member. 2. The image forming apparatus according to claim 1, wherein the charge eliminating member is configured such that all the tips of the charge eliminating member are brought into contact with the surface of the housing member by bending the tip of the charge eliminating member. . 3. The static eliminator member is configured so that all the tips of the static eliminator are brought into contact with the surface of the housing member by urging the tip of the static eliminator to come into contact with the surface of the housing member by urging means. The image forming apparatus according to claim 1, wherein the image forming apparatus is formed.