JP2001154490A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carrier scraping device capable of restraining carrier from passing through and having high carrier scraping efficiency. SOLUTION: This image forming device is provide with an image support PR where an image is developed to a toner image by a developing device G having two-component developer having the carrier and toner, a carrier transport member 26 equipped with a cylindrical magnet roll 27 where a plurality of magnetic poles extending in the axial direction are arranged some intervals in the circumferential direction and a cylindrical non-magnetic carrier transport sleeve 28 rotationally moving in a state where it oppositely approaches to the surface of the image carrier PR with its outer side surface coated, and a carrier scraping blade 33 which is arranged toward an upstream side in the rotating direction of the sleeve 28 from the peak position of magnetic field formed on the surface of the sleeve 28 by one of the magnetic poles and whose tip edge 33a abuts on the image support PR.

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, and more particularly, to an image forming apparatus having a carrier scraping device for scraping a carrier adhered to the surface of a cylindrical carrier conveying member.

[0002]

2. Description of the Related Art As an image forming apparatus having a carrier scraping device of the type described above, the following technology (J1) is conventionally known. (J1) Technology described in Japanese Patent Application Laid-Open No. 7-306596. In this publication, when only toner is supplied from a developer carrying member to a photoreceptor in a two-component developing device, a carrier erroneously attached to the photoreceptor is transferred. Previously, a carrier scraping device has been described. In this carrier scraping device, a cylindrical sleeve surface having a fixed magnet therein is arranged close to a photoreceptor surface, and a carrier attached to the sleeve is scraped off at a predetermined position by a scraper (blade).

[0003]

[Problem to be Solved by the Invention] (Problem of (J1)) Since the free end of the scraper comes into frictional contact with the sleeve surface with a predetermined pressing force, the tip of the scraper and the surface of the sleeve gradually change over time. Wear progresses. For this reason, the contact surfaces of the two become non-uniform, so that the carrier on the sleeve cannot be scraped over time, resulting in an image quality defect. In particular, in the case of a small particle size carrier in an image forming apparatus aimed at improving image quality in recent years, carrier leakage from a non-uniform contact surface is promoted, and image quality tends to be defective. Therefore, in the carrier scraping device, it is necessary to make the friction contact surface between the sleeve surface and the scraper uniform and to make the contact pressure uniform.

[0004] Although different from a device for scraping a carrier on a cylindrical sleeve, the following technology is conventionally known as a technology for making the layer thickness of a one-component developer (magnetic toner) attached on a rotating sleeve uniform. is there. (J2) Technique described in Japanese Patent Application Laid-Open No. 9-211971 This publication describes a magnetic toner (one-component developer without using a carrier) on a rotating sleeve having a fixed magnet therein.
A technique using a magnetic scraper to make the layer thickness of the magnetic recording medium constant is described. Since the free end of the magnetic scraper is arranged to face the magnetic pole of the fixed magnet inside the sleeve, it is considered that the magnetic force is attracted to the sleeve surface with a uniform force by the magnetic force, and abuts on the sleeve surface with a uniform contact pressure. (Problem of the above (J2)) The technology described in this publication is a technology for making the layer thickness of the magnetic toner on the sleeve constant, so that the magnetic toner on the sleeve passes between the sleeve and the magnetic scraper. And cannot be used to scrape the carrier on the sleeve.

The following technique is conventionally known as a technique for scraping a one-component developer (magnetic toner) attached to a rotating sleeve, which is different from a device for scraping a carrier on a cylindrical sleeve. (J3) Japanese Patent Application Laid-Open No. 8-76594 discloses a cleaning member for removing magnetic toner remaining on an image carrier in contact with the image carrier, and a cleaning member disposed below the cleaning member. A fixed sleeve having a sleeve that receives and conveys the magnetic toner dropped from the member and rotates in a forward direction with respect to the rotation direction of the image carrier, and a magnetic pole disposed in the sleeve and disposed at a position away from the image carrier. A cleaning device including a magnet roll and a magnetic scraper disposed with a free end facing the magnetic pole is described. (Problem of the above (J3)) The technology described in this publication is a technology for scraping magnetic toner. When the carrier is scraped using the technology described in this publication, the pressing force of the magnetic scraper against the sleeve is obtained. If the value is too small, there is a problem that the carrier slips through.

As a result of the experiment, the inventor of the present invention has determined that the contact position of the leading edge of the magnetic scraper with respect to the sleeve surface is located on the upstream side of the sleeve surface in the rotational movement direction from the position facing the magnetic pole of the magnet inside the sleeve. It has been found that career slippage is reduced.

SUMMARY OF THE INVENTION In view of the foregoing, the present invention provides a carrier having a carrier scraping blade (scraper) in which a fixed magnet is disposed and abuts against the surface of a rotating carrier transport sleeve to scrape off the carrier attached to the sleeve surface. An object of the scraping device is to describe the following (O01) and (O02). (O01) To provide a carrier scraping device which has little carrier slip-through and high carrier scraping efficiency. (O02) To make the pressure contact force between the edge of the tip of the carrier scraping blade and the carrier transport sleeve small and uniform.

[0008]

Means for Solving the Problems Next, the present invention for solving the above-mentioned problems will be described. Elements of the present invention are described in order to facilitate correspondence with the elements of the embodiments described later. The sign of parentheses is added in parentheses. The reason why the present invention is described in correspondence with the reference numerals of the following embodiments is to facilitate understanding of the present invention, and not to limit the scope of the present invention to the embodiments.

(Invention) In order to solve the above-mentioned problems, an image forming apparatus of the invention is characterized by having the following requirements (A01) to (A03). (A01) An electrostatic latent image formed by irradiating a light beam on the surface of a rotating and moving image carrier (PR) uniformly charged in a charged area (Q0) has a two-component developer having a carrier and a toner. An image carrier (PR) which is developed into a toner image by a developing device (G); (A02) a cylindrical magnet roll (27, R0a) fixedly supported and having axially extending magnetic poles spaced in a circumferential direction; A plurality of magnet rolls (27, R0a), and the magnet rolls (27, R0
0a) with the outer surface thereof covered and the image carrier (P
R) a carrier transport member (26, R) having a cylindrical non-magnetic carrier transport sleeve (28, R0b) having a sleeve surface that rotates and moves in a state facing and approaching the surface;
(A03), (A03) The carrier transport sleeve (28, R0b) is determined from the peak position of the magnetic field formed by one of the plurality of magnetic poles on the surface of the carrier transport sleeve (28, R0b).
b) The leading edge (31a, 3) is located at the position on the upstream side in the rotation direction.
3a) a carrier scraping blade (31, 33) which abuts and whose tip is located upstream of the carrier transport sleeve (28, R0b).

(Function of the Present Invention) In the image forming apparatus of the present invention having the above-described configuration, the surface of the image carrier (PR) that rotates and moves is uniformly in the charged area (Q0). The electrostatic latent image is formed by being charged and irradiated with a light beam, and the electrostatic latent image includes a carrier and a toner.
The toner image is developed by a developing device (G) having a component developer. The carrier transport member (26, R0) is a fixedly supported cylindrical magnet roll (27, R0a), in which a plurality of magnetic poles extending in the axial direction are arranged at intervals in the circumferential direction. , R0a) and a cylindrical non-magnetic carrier transport sleeve (28, R0b) that rotates and moves while covering the outer surface of the magnet roll (27, R0a).
And The carrier transport sleeve (28, R0b)
The surface of the sleeve rotates while facing and approaching the surface of the image carrier (PR). Such a carrier transport sleeve (28, R0b) includes a developing sleeve (R0b) used in the developing device (G) or a carrier collecting device (K) for collecting a carrier adhered to the surface of the image carrier (PR). And a carrier collection sleeve (28). The carrier scraping blades (31, 33) are provided at their leading edges (31).
a, 33a) is the carrier transport sleeve (28, R0).
It is arranged facing the upstream side of b). Edges (31a, 33) at the tips of the carrier scraping blades (31, 33)
Part a) is such that one magnetic pole of the plurality of magnetic poles of the magnet roll (27, R0a) is the carrier transport sleeve (28, R0a).
R0b) abuts on the upstream side in the rotation direction of the carrier transport sleeve (28, R0b) from the peak position of the magnetic field formed on the surface. The carrier scraping blade (31, 33)
Due to the arrangement of the edges (31a, 33a) at the tip, even if the pressure contact force between the edges (31a, 33a) and the sleeve surface is small, the carrier does not slip through the sleeve and the carrier scraping efficiency is increased. Can be.

[0011]

(Embodiment 1) The embodiment 1 of the image forming apparatus of the present invention has the following requirements (A0) in the present invention.
(A04) wherein the tip position of the carrier scraping blade (31, 33) and the peak position of the magnetic field are the carrier transport sleeve (28, R0b).
(Radian), the magnetic field at the peak position of the magnetic field is Mp (mT), and the radius of the carrier transport sleeve (28, R0b) is r (mm). The carrier transport member (2)
6, R0) and the carrier scraping blade (3
1,33), 38.1 ≦ Mp / rθ ≦ 119.4.

(Operation of the First Embodiment) In the first embodiment of the image forming apparatus according to the present invention having the above-described configuration, the carrier transport member (26, R0) and the carrier scraping blades (31, 33) are provided. Since the above formula is satisfied, the carrier adhered and transported on the surface of the carrier transport sleeve (28, R0b) is scraped by the magnetic pole when approaching the tip of the carrier scraping blade (31, 33). It is attracted to the magnetic field formed on the upper surface of the removing blade (31, 33), moves to the upper surface of the carrier scraping blade (31, 33), and is scraped off the surface of the carrier transport sleeve (28, R0b). That is,
It is possible to prevent the carrier from slipping between the tip of the carrier scraping blade (31, 33) and the surface of the carrier transport sleeve (28, R0b). Therefore, the carrier scraping efficiency is improved.

(Embodiment 2) Embodiment 2 of the image forming apparatus of the present invention is characterized in that the following requirement (A05) is provided in the present invention or Embodiment 1. (A05) The carrier transport member (26, R) disposed at a position downstream of the developing device (G) and upstream of the transfer area (Q4) in the rotational movement direction of the surface of the image carrier (PR).
0).

(Operation of the Second Embodiment) In the second embodiment of the image forming apparatus of the present invention having the above-described configuration, the downstream side of the developing device (G) in the rotational movement direction of the surface of the image carrier (PR). The carrier on the surface of the image carrier (PR) is located on the side of the transfer area (Q4) and on the upstream side of the transfer area (Q4).
6, R0) on the surface of the carrier transport sleeve (28, R0b). Therefore, it is possible to prevent the carrier from being transported to the transfer area (Q4), and to prevent the carrier from being transferred from the image carrier (PR) to the transfer material (recording sheet or the like) (S) in the transfer area (Q4). Can be.

(Embodiment 3) Embodiment 3 of the image forming apparatus of the present invention is characterized in that the following requirement (A06) is provided in the present invention or Embodiment 1 or 2. (A06) The carrier scraping blade (31, 33) made of a magnetic material.

(Effect of Third Embodiment) In the third embodiment of the image forming apparatus of the present invention having the above-described configuration, the carrier scraping blades (31, 33) are made of a magnetic material. The tip of the carrier scraping blade (31, 33) is attracted by the magnetic force of the magnet roll (27, R0a) of (26, R0), and the edge (31a, 33a) is formed on the surface of the carrier transport sleeve (28, R0b).
Abuts. The magnetic force is applied to the carrier scraping blade (3
1, 33) Since it uniformly acts on the entire region in the width direction of the tip, the carrier transport sleeve (28, R
0b) It is easy to make the contact pressure of the edges (31a, 33a) to the surface uniform. In this case, the carrier has the edge (31a, 33a) and the carrier transport sleeve (28, R0).
b) It can be prevented from slipping through the surface.

(Embodiment 4) An embodiment 4 of the image forming apparatus of the present invention is characterized in that the following requirement (A07) is provided in any one of the above-mentioned present invention and Embodiments 1 to 3. . (A07) The carrier scraping blade (31, 33)
When the angle between the tip position of the magnetic field and the peak position of the magnetic field with respect to the center of the carrier transfer sleeve (28, R0b) is θ (radian), 4 ° ≦ θ ≦ 10 °. A carrier conveying member (26, R0) and the carrier scraping blade (31, 33);

(Effect of Embodiment 4) In Embodiment 4 of the image forming apparatus of the present invention having the above configuration, the carrier scraping blades (31, 33) made of a magnetic material are attracted to the magnetic pole. Carrier transport sleeve (28, R0
b) The surface is pressed by magnetic force. Since the magnetic force acts uniformly on the entire area in the width direction of the carrier scraping blades (31, 33), the edge (31a, 33) on the surface of the carrier transport sleeve (28, R0b) having the above configuration is formed.
It is easy to make the contact pressure a) uniform. Also,
When the angle θ satisfies the expression 4 ° ≦ θ ≦ 10 °, the edge (31) at the tip of the carrier scraping blade (31, 33)
a, 33a) is attracted to the magnetic field formed on the surface of the carrier scraping blade (31, 33) by the magnetic poles, and the carrier scraping blade (3, 33a).
1, 33), and the carrier transport sleeve (2
8, R0b) scraped from the surface. For this reason, the carrier can be prevented from staying at the tip of the carrier transport sleeve (28, R0b), and a part of the staying carrier can be edged (3, R0b).
1a, 33a) and the surface of the carrier transfer sleeve (28, R0b) can be prevented from slipping.

(Embodiment 5) An embodiment 5 of the image forming apparatus of the present invention is characterized in that the following requirement (A08) is provided in any of the above-mentioned embodiments of the present invention or Embodiments 1 to 4. . (A08) In order to clean the surface of the image carrier (PR), on the upstream side of the charging area (Q0) and the downstream side of the transfer area (Q4) in the rotational movement direction of the surface of the image carrier (PR). The cleaner, wherein the cleaner has the carrier transport member (26, R0).

(Effect of Fifth Embodiment) In the fifth embodiment of the image forming apparatus according to the present invention having the above-described configuration, the surface of the image carrier (PR) is cleaned to clean the surface of the image carrier (PR). The cleaner disposed on the upstream side of the charging area (Q0) in the rotational movement direction and on the downstream side of the transfer area (Q4) has the carrier transport member. Therefore, the carrier adhered to the surface of the image carrier (PR) is collected by the carrier conveying member of the cleaner.

(Examples) Next, specific examples (examples) of the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples. To facilitate understanding of the following description, in the drawings, the front-back direction is the X-axis direction, the right-left direction is the Y-axis direction, and the up-down direction is the Z-axis direction.
Axial direction and directions indicated by arrows X, -X, Y, -Y, Z, -Z or sides indicated are forward, rear, right, left, upper, lower, or front, rear, right, respectively. , Left side, upper side, lower side. Also, in the figure, those in which “•” is described in “○” mean an arrow pointing from the back of the paper to the front,
A mark with "x" in "o" means an arrow pointing from the front to the back of the paper.

Embodiment 1 FIG. 1 is an overall explanatory view of an image forming apparatus provided with a carrier scraping device according to Embodiment 1 of the present invention. 1, the image forming apparatus U has a main body U1 and an automatic document feeder U2 placed on a platen glass PG on the upper surface of the main body U1. The automatic document feeder U2 has a document feed tray TG1 on which a plurality of documents Gi to be copied are stacked. The plurality of originals Gi placed on the original feed tray TG1 are sequentially passed through a copy position on the platen glass PG and discharged to the original discharge tray TG2. The automatic document feeder U2 is rotatable with respect to the copying machine U1 by a hinge shaft (not shown) extending at the rear end (-X end) and extending in the left-right direction. Is rotated upward when placed on the platen glass PG by hand.

The image forming apparatus main body U1 has a UI (user interface) for a user to input an operation command signal such as a copy start signal. The IIT as an original reading device disposed below the transparent platen glass PG on the upper surface of the copying machine main body U1 has an exposure optical system A. In the case of the ADF mode in which copying is performed using the automatic document feeder (auto document feeder) U2,
When the exposure optical system A is stopped at the home position, each document Gi sequentially passes through the copy position on the platen glass PG.
Is exposed. Platen glass P by the operator
In the case of the platen mode in which copying is performed on the sheet G, the exposure optical system A scans the original on the platen glass PG while moving. The reflected light from the document Gi exposed by the lamp of the exposure optical system A passes through the exposure optical system A and is converged on a CCD (solid-state imaging device). Said C
The CD outputs an electric signal corresponding to the amount of reflected light of the document converged on its imaging surface.

The controller C includes an IPS (image processing system), a power supply circuit (a developing device, a transfer roll,
The operation timing of the power supply circuit E of the fixing device and the laser drive circuit DL is controlled. The IPS (image processing system) converts the electric signal input from the CCD into image data and temporarily stores the image data, and converts the image data at a predetermined timing as image data for forming a latent image into an IOT (image output). To the laser drive circuit DL of the terminal. The laser drive circuit DL outputs a laser drive signal ROS according to the input image data.
(Latent image forming apparatus).

Image carrier P constituted by a photosensitive drum
R rotates in the direction of the arrow Ya, and after its surface is uniformly charged by the charger CR in the charging area Q0,
The ROS (latent image forming apparatus) at the latent image writing position Q1
Is exposed and scanned by the laser beam L to form an electrostatic latent image. The electrostatic latent image on the rotating image carrier PR is developed into a toner image by a developing device G in a developing area Q2,
Carriers adhering to the surface of the image carrier PR during development are collected by the carrier collection device K in the carrier collection area Q3. The developing device G and the carrier collecting device K will be described later in detail. The surface of the image carrier PR on which the toner image has been formed moves to the transfer area Q4. Below the transfer area Q4, a slide frame Fs, which is slidable back and forth (in a direction perpendicular to the paper surface) by a pair of left and right slide rails SR, is detachably supported with respect to the image forming apparatus main body. . The slide frame Fs supports a transfer roll T, a transfer roll cleaner CLt, a roll support lever Lr, a post-transfer sheet guide SG2, and a sheet transport belt BH.

The roll support lever Lr is a rotatable lever that supports the transfer roll T and the transfer roll cleaner CLt. The roll support lever Lr is rotated by a motor (not shown) to move the transfer roll T
It is moved between a transfer position in contact with the image carrier PR and a jam processing position remote from the image carrier PR. The post-transfer sheet guide SG2 guides the recording sheet S, which has passed the transfer area Q4, which is the contact area between the transfer roll T and the image carrier PR, to the downstream sheet conveying belt BH.

Below the slide frame Fs, a first paper feed tray TR1 for storing recording sheets S, an intermediate tray TR0 used for double-sided copying, etc., and a second paper feed tray TR
2. The third paper feed tray TR3 is detachably housed.
The intermediate tray TR0 is a tray used when reversing the recording sheet S on which the first copy has been performed at the time of double-sided copying or the like and re-transmitting it to the transfer area Q4. The first
A manual feed tray TRt is provided at an upper right position of the paper feed tray TR1. Each recording sheet S sent from the manual feed tray TRt or each of the paper feed trays TR0 to TR3 is
The sheet is conveyed to the transfer area Q4 through the first sheet conveying path SH1.

The recording sheets S stored in the paper feed trays TR0 to TR3 are picked up by a pickup roll R at a predetermined timing.
It is taken out by p, separated one by one by the separating roll Rs, transported by a plurality of transport rolls Ra, and transported to the registration roll Rr. The recording sheet S conveyed to the registration roll Rr is conveyed from the pre-transfer sheet guide SG1 to the transfer area Q4 in time with the movement of the toner image on the image carrier PR to the transfer area Q4. In the transfer area Q4, the transfer roll T is attached to the image carrier PR.
The upper toner image is electrostatically transferred to the recording sheet S. The residual toner is removed from the surface of the image carrier PR after the transfer by the image carrier cleaner CLp. Further, the toner adhered to the surface of the transfer roll T is collected by the transfer roll cleaner CLt.

The recording sheet S to which the toner image has been transferred
Are the sheet guide SG2 after the transfer, the sheet conveying belt BH
Is transferred to the fixing area Q5, and when passing through the fixing area Q5, is heat-fixed by a fixing device F having a pair of fixing rolls composed of a heating roll Fh and a pressure roll Fp. The recording sheet S on which the toner image is fixed is conveyed to the sheet discharge path SH2 or the sheet reversal path SH3 by the conveyance path switching gate GT1. The recording sheet S conveyed to the sheet discharge path SH2 is discharged to the recording sheet discharge tray TRh by the conveying rolls Ra and Rh, and the recording sheet S conveyed to the sheet reversing path SH3 is reversed and then conveyed to the intermediate tray TR0. Is done. The sheet transport path S
The sheet conveying device SH is constituted by H1, the sheet discharge path SH2, the sheet reversing path SH3, and the elements indicated by the reference numerals Rp, Rs, Rr, SG1, SG2, BH, Ra and the like.

(Developing Unit G) FIG. 2 is an enlarged explanatory view of a main part of FIG. 1 and is an explanatory view of a developing device and a carrier collecting device. FIG. 3 is a perspective view of a developing device as a main part of the developing device. FIG. 4 is an enlarged explanatory view of a developer supply port portion of the developing device shown in FIG. 3 and is a partial cross-sectional view as seen from the direction of arrow IV in FIG. FIG. 5 is an explanatory view of the developing device, and FIG.
5B is a sectional view taken along line VA-VA, FIG. 5B is a sectional view taken along line VB-VB in FIG. 4, and FIG. 5C is an explanatory view of a rotational force transmission gear of the developing device. 2 to 5, a developing device G arranged opposite to the image carrier PR in the developing area Q2 is a developing container for containing a two-component developer composed of a negatively charged toner and a positively charged magnetic carrier. V. 3, a developing container V includes a developing container main body 1 and a front connecting member 2 connected to a front end (X end) and a rear end (−X end) of the developing container main body 1 (see FIGS. 3 and 5A). And a rear connection member 3. The front connecting member 2 has a front upper connecting member 2a and a front lower connecting member 2b, and the rear connecting member 3 has a rear upper connecting member 3a and a rear lower connecting member 3b. In FIG. 3, the developing container main body 1
A pair of supported portions 1a, 1a are provided at upper portions of the front end and the rear end, respectively. When the developing container V is mounted inside the image forming apparatus U, each of the supported portions 1a is provided.
Are supported by a frame (not shown) of the image forming apparatus U.

In FIG. 5, a developing roll (developer conveying member) R0 is provided inside a developing container V formed by the developing container main body 1, the front connecting member 2 and the rear connecting member 3.
And a stirring and conveying member R1, R2 and a stirring member (retaining developer stirring member) R3.
0a and a rotatable developing sleeve (developer conveying sleeve) R0b that covers the outer surface of the magnet roll R0a. A partition wall 4 (see FIG. 5B) is provided between the stirring and conveying members R1 and R2. The partition wall 4 divides the inside of the developing container V into upper and lower parts. At the front end and the rear end of the partition wall 4, communication ports 4a and 4b (only 4a is shown) are formed to communicate vertically, and the developer in the developing container V is circulated by the stirring and conveying members R1 and R2. While stirring.

5A and 5B, a stirring member R3 (FIG. 5B) is provided between the stirring and conveying member R2 and the developing roll R0.
See). The stirring member R3 is a member for stirring and conveying the developer remaining between the stirring and conveying member R2 and the developing roll R0. 2 to 4,
A developer supply port 6 is provided above the front connection member 2 and at the front end.
Are formed. 3, 4 and 5A, a developer discharge port 7 is formed on the upper side surface of the front connection member 2. The developer discharge port 7 is provided at a position upstream of the developer supply port 6 (in the rearward direction) from the position of the developer supply port 6 in order to reduce the rate at which new developer supplied from the developer supply port 6 is discharged immediately after replenishment. (End side). In FIG. 5B, a layer thickness regulating member 8 for regulating the layer thickness of the developer on the developing roll R0 is disposed in the developing container V. The developing containers V (1 to 8) in this embodiment are constituted by the elements indicated by the reference numerals 1 to 8.

Referring to FIGS. 2 and 5C, the developing roll R
The gear G0 is attached to the rear end (-X end) of the 0 axis,
Gears G1, G2, G3 are mounted on the rear ends of the shafts of the stirring and conveying members R1, R2 and R3. Gear G0 and gear G
1 meshes via an intermediate gear G4. Gear G
1, G2 and G3 are sequentially engaged. During the developing operation, the rotational force of the gear G0 is sequentially changed to the gears G4, G1, G2, G
Conveyed to 3. At this time, the developing roll R0, the stirring and conveying members R1, R2, and the stirring member R3 rotate.

In FIG. 2, a developer supply cylinder support member 11 is disposed above the developer supply port 6 of the developer container V. A developer supply cylinder 12 is connected to the developer supply cylinder support member 11. The inside of the developer supply cylinder 12 is connected to the developer supply port 6 of the developing container V via the inside of the developer supply cylinder support member 11. Communicate with In the developer supply cylinder 12, a supply developer transport member R4 is rotatably disposed. A gear G5 (see FIG. 2) is fixed to one end of the rotating shaft of the replenishment developer transport member R4, and the replenishment developer transport member R4 is rotationally driven by a developing device motor (not shown) that meshes with the gear G5. It has become so.

In FIG. 2, a developer supply case 14 is disposed above the developing container V. The developer supply case 14 is a two-component developer having a high toner concentration (hereinafter, referred to as a two-component developer).
A high-concentration developer) and a developer stirring container 17 provided below the developer storage container 16. The two-component developer (high-concentration developer) supplied from the developer storage container 16 to the developer stirring container 17 is stirred while being circulated in the developer stirring container 17, and is supplied to the supply cylinder connection port 1.
7a, the developer is supplied to the developer supply cylinder 12. A developer replenishing device (11 to 17 + G5) is composed of the components denoted by reference numerals 11 to 17 and G5. The high-concentration developer supplied from the developer storage container 14 into the developer supply cylinder 12 is transported by the revolving developer transport member R4 that is driven to rotate, and is supplied into the developer container V from the developer supply port 6. It has become so. Replenishment of this high concentration developer
In normal use, the detection is performed based on a detection value of a toner image density sensor (not shown) which detects the density of the density detection toner image formed on the image carrier PR.

In FIGS. 3 and 5A, a discharge developer transport tube connecting portion 21 is disposed outside the developer discharge port 7 (see FIGS. 5A and 3) of the developing container V. The front end portion (X end) of the discharge developer transfer tube 22 is connected to the discharge developer transfer tube connection portion 21, and the rear end portion (−X end portion) of the discharge developer transfer tube 22 is connected. ) Contains a developer collection container 2
3 (see FIG. 3) is connected. In FIG. 3, a discharge developer transport member R5 is disposed inside the discharge developer transport tube 22.

In FIG. 3, a gear G6 is mounted on the rear end of the rotating shaft of the discharging developer conveying member R5. The gear G6 meshes with a gear G7 meshing with the gear G2. When G2 rotates, the discharge developer transport member R5 rotates via gears G7 and G6. By the rotation of the discharge developer transport member R5, the excess developer discharged from the developer discharge port 7 into the discharge developer transport tube 22 through the discharge developer transport tube connecting portion 21 is removed by the developing device. It is conveyed to the agent collection container 23.

A carrier collecting device K (see FIG. 2) is arranged adjacent to a carrier collecting area Q3 set along a rotational movement path on the surface of the image carrier PR, and the carrier collecting area Q3 is provided with the image. It is set at a position downstream of the developing device G in the rotational movement direction of the surface of the support PR and upstream of the transfer area Q4. Note that the carrier collection device K can be disposed downstream of the transfer area Q4,
It is necessary to arrange on the upstream side of the charging area Q0. The carrier collection device K has a carrier collection container 25. A carrier transport roll (carrier transport member) 26 is accommodated in the carrier recovery container 25, and the carrier transport roll 26 faces the image carrier PR with the carrier recovery area Q3 interposed therebetween. Carrier transport roll 2
Reference numeral 6 denotes a fixedly supported cylindrical magnet roll 27 and a rotating cylindrical carrier transport sleeve 28 arranged so as to surround the outer periphery thereof. A plurality of magnetic poles extending in the axial direction are arranged on the magnet roll 27 at intervals in the circumferential direction. The positions of the magnetic poles are indicated by S and N. The carrier transport sleeve 28 includes a magnet roll 27
A cylindrical member that rotates while covering the outer surface of the
The surface rotates and moves while facing and approaching the surface of the image carrier PR.

FIG. 6 shows that the carrier scraping action differs depending on the positional relationship between the position of the magnetic pole of the magnet roll of the carrier transport roll and the position of the edge of the tip of the carrier scraping blade (31, 33) abutting on the surface of the carrier transport sleeve. FIG. 6A is an explanatory diagram of the present example, and FIG. 6B is an explanatory diagram of a comparative example. The carrier transport sleeve 28
The carrier scraping blade 31 made of a magnetic material, which scrapes the carrier attached to the surface of the carrier transport sleeve 28 by contacting the surface of the rotating sleeve, is supported by a blade support member 32. Carrier scraping blade 3
The edge 1a of the tip abuts on a position on the upstream side in the rotation direction of the carrier transport sleeve 28 from a peak position of a magnetic field formed by one of the plurality of magnetic poles on the surface of the carrier transport sleeve 28, and Are arranged facing the upstream side of the carrier transport sleeve 28.

In this embodiment, r, θ, and Mp are defined as follows. r (mm): radius of the carrier transport sleeve. θ (radian): the angle formed by the edge position of the tip of the carrier scraping blade 31 in contact with the surface of the carrier transfer sleeve 28 and the peak position of the magnetic field of the magnet roll 27 with respect to the center of the carrier transfer sleeve 28. Mp (mT): magnetic field strength at the peak position of the magnetic field. In this embodiment, the following settings are made. The reason will be described later in the section of operation of the embodiment. r = 8 (mm) θ = 7π / 180 (radian) = 7 ° Mp = 50 (mT)

As described above, r = 8 mm, Mp = 5
In the case of 0 mT, when the value of θ ° was in the range of the following equation (1), the carrier was scraped off with almost no slip-through. 4 ° ≦ θ ≦ 10 ° (1) In the above equation (1), when θ is expressed in radians, the following equation is obtained. (2)
Becomes 4π / 180 ≦ θ (radian) ≦ 10π / 180 (2) In general, the carrier transporting roll 26 and the carrier scraping blade 31 are used when Mp and r change. Experiments have shown that, by configuring or arranging so that θ satisfies the following expression (3), the carrier on the carrier transport sleeve 28 can be scraped satisfactorily. 38.1 ≦ Mp / rθ ≦ 119.4 ……………………………… (3)

(Operation of Embodiment 1) In the carrier scraping device of the embodiment having the above-described configuration, a part of the carrier on the developing roll R0 may be transferred onto the image carrier PR in the developing area Q2. This carrier is attracted by a magnetic force to a carrier transport sleeve 28 rotating outside the magnet roll 27 in the carrier recovery area Q3. The carrier sucked on the carrier transport sleeve 28 moves toward the contact portion of the edge 31a at the tip of the carrier scraping blade 31 with the rotation of the carrier transport sleeve 28 (see FIG. 6A).

When θ satisfies the above formula (1) or (2) in FIG. 6A, the carrier approaching the edge edge 31a at the tip of the carrier scraping blade 31 is moved by the magnetic pole S shown in FIG.
It is attracted to the magnetic field formed on the upper surface, moves to the upper surface of the carrier scraping blade 31, and is scraped from the surface of the carrier transport sleeve. Also, θ is calculated by the above equation (1).
Alternatively, when the condition (2) is satisfied, the carrier scraping blade 31 made of a magnetic material is attracted to the magnetic pole S shown in FIG. 6A and pressed against the surface of the carrier transport sleeve 28 by magnetic force. Since the magnetic force acts uniformly on the entire area of the carrier scraping blade 31 in the width direction, it is easy to make the contact pressure of the edge 31a on the surface of the carrier transport sleeve 28 having the above-mentioned configuration uniform. In this case, it is possible to prevent the carrier from staying at the tip of the carrier transport sleeve 28, and to prevent a state in which a part of the staying carrier slips between the edge 31a and the surface of the carrier transport sleeve 28.

In contrast to the embodiment shown in FIG. 6A, FIG.
In the case where the edge 31a is arranged at a position facing the magnetic pole S as in the prior art shown in FIG.
8. The carrier stays at the tip and a part of the staying carrier is
A problem arises in that it slips through between a and the surface of the carrier transport sleeve 28. Further, the contact position of the edge 31a on the surface of the carrier transport sleeve 28 is the same as that in FIG.
6B, the carrier stays at the leading end of the carrier transport sleeve 28 and stays in the same manner as in the case described with reference to FIG. 6B. A problem arises in that a part of the carrier that has slipped between the edge 31a and the surface of the carrier transport sleeve 28.

The above equations (1) and (2) represent the radius r (mm) of the carrier transport sleeve 28 and the magnetic field strength Mp at the peak position of the magnetic field on the surface of the carrier transport sleeve 28.
(MT) is an equation that defines an appropriate range of θ when the value of r and the next intensity Mp are not determined, but the value of θ (radian) is determined by the equation (1). Alternatively, by setting the distance in the range represented by the above equation (3), the carrier can be prevented from staying at the tip of the carrier transport sleeve 28, and a part of the staying carrier can be prevented from being edge 3
It is possible to prevent occurrence of slippage between 1a and the surface of the carrier transport sleeve 28.

(Embodiment 2) FIG. 7 is an explanatory view of a main part of Embodiment 2 of an image forming apparatus provided with a carrier scraping device of the present invention. In FIG. 7, a developing roll (a developer conveying member for conveying a developer including a carrier, that is, a carrier conveying member) R0 includes a magnet roll R0a and a rotatable developing sleeve (a carrier for covering the outer surface of the magnet roll R0a). Developer transport sleeve that transports the developer containing, that is,
A carrier transport sleeve) R0b, and a plurality of magnetic poles extending in the axial direction are arranged on the magnet roll R0a at intervals in the circumferential direction. The positions of the magnetic poles are indicated by S and N. The developing sleeve (carrier conveying sleeve) R0b is a cylindrical member that rotates while covering the outer surface of the magnet roll R0a, and the surface thereof is formed of the image carrier P0.
It rotates while facing and approaching the R surface.

The carrier scraping action is performed by the positional relationship between the magnetic pole position of the magnet roll R0a of the developing roll R0 shown in FIG. 7 and the position of the edge 33a of the tip of the carrier scraping blade 33 abutting on the surface of the developing sleeve (carrier transport sleeve). Are similar to the carrier transport member 26 and the carrier scraping blade 31 of the first embodiment described with reference to FIG. 6A. Accordingly, the positional relationship between the position of the magnetic pole of the magnet roll R0a of the developing roll R0 and the position of the edge 33a of the tip of the carrier scraping blade 33 which is in contact with the surface of the developing sleeve (carrier transport sleeve) is expressed by the equation (1) in the first embodiment. Meets. Therefore,
The carrier adhered to the developing sleeve R0b of this embodiment can be scraped off without being slipped off by the edge 33a of the carrier scraping blade 33.

(Modifications) Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above-described embodiments, but falls within the scope of the present invention described in the appended claims. Thus, various small design changes can be made. next,
The modification of this invention is illustrated. (H01) The carrier transport sleeve can be provided in a cleaner that collects the developer on the surface of the image carrier.

[0049]

The image forming apparatus of the present invention has the following effects (E01) and (E02). (E01) By setting the contact position of the edge of the tip of the carrier scraping blade with respect to the surface of the carrier transport sleeve at an appropriate position with respect to the peak position of the magnetic field, the carrier with little carrier slip-through and high carrier scraping efficiency is obtained. A scraping device can be provided. (E02) Since the carrier scraping blade made of a magnetic material is used, the pressure contact force between the edge of the tip of the carrier scraping blade and the carrier transport sleeve can be made small and uniform.

[Brief description of the drawings]

FIG. 1 is an overall explanatory diagram of an image forming apparatus including a carrier scraping device according to a first embodiment of the present invention.

FIG. 2 is an enlarged explanatory view of a main part of FIG. 1, and is an explanatory view of a developing device and a carrier collecting device.

FIG. 3 is a perspective view of a developing device as a main part of the developing device.

FIG. 4 is an enlarged explanatory view of a developer supply port portion of the developing device shown in FIG. 3 and is a partial cross-sectional view seen from the direction of arrow IV in FIG. 2;

FIG. 5 is an explanatory view of the developing device, and FIG.
5B is a sectional view taken along line VA-VA, FIG. 5B is a sectional view taken along line VB-VB in FIG. 4, and FIG. 5C is an explanatory view of a rotational force transmission gear of the developing device.

FIG. 6 is a view showing that the carrier scraping action differs depending on the positional relationship between the magnetic pole position of the magnet roll of the carrier transport roll and the position of the edge of the tip of the carrier scraping blade abutting on the surface of the carrier transport sleeve. ,
FIG. 6A is an explanatory diagram of the present embodiment, and FIG. 6B is an explanatory diagram of a comparative example.

FIG. 7 is an explanatory view of a main part of an image forming apparatus having a carrier scraping device according to a second embodiment of the present invention.

[Explanation of symbols]

26, R0: Carrier conveying member, 27, R0a: Magnet roll, 28: Carrier conveying sleeve (carrier collecting sleeve), 31, 33: Carrier scraping blade, 31
a, 33a: edge; G: developing device; K: carrier recovery device; PR: image carrier; Q0: charging area; R0b: carrier transport sleeve (developing sleeve).

Claims (4)

[Claims] 1. An image forming apparatus having the following requirements (A01) to (A03): (A01) formed by irradiating a light beam on a surface of a rotating and moving image carrier uniformly charged in a charging area. An image carrier in which an electrostatic latent image is developed into a toner image by a developing device having a two-component developer having a carrier and a toner; (A02) a cylindrical magnet roll fixedly supported and having a magnetic pole extending in the axial direction; A cylindrical shape having a plurality of the magnet rolls arranged at intervals in a circumferential direction, and a sleeve surface rotating and moving in a state of covering the outer surface of the magnet roll and facing and close to the surface of the image carrier; (A03) a carrier transport member having a non-magnetic carrier transport sleeve according to (A03), wherein one of the plurality of magnetic poles determines a carrier transport position from a peak position of a magnetic field formed on the surface of the carrier transport sleeve; Over Bed rotational direction of the upstream side of the tip of the edge position contacts and said tip is scraped carrier disposed facing the upstream side of the carrier transport sleeve blades. 2. The image forming apparatus according to claim 1, wherein the image forming apparatus satisfies the following requirement (A04): (A04) the tip position of the carrier scraping blade and the peak position of the magnetic field are set with respect to the center of the carrier transport sleeve. When the angle formed is θ (radian), the magnetic field at the peak position of the magnetic field is Mp (mT), and the radius of the carrier transport sleeve is r (mm), 38.1 ≦
The carrier transporting member and the carrier scraping blade configured to satisfy Mp / rθ ≦ 119.4. 3. The image forming apparatus according to claim 1, wherein the image forming apparatus satisfies the following requirement (A05): (A05) downstream of the developing device in a rotational movement direction of the surface of the image carrier and upstream of a transfer area. The carrier transport member disposed at a position on the side of the carrier. 4. The image forming apparatus according to claim 1, which satisfies the following requirement (A06): (A06) The carrier scraping blade made of a magnetic material.