JPH09236986A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely execute recovering toner, and to improve developing efficiency, by making condition of the toner on an image carrier easily stuck to a magnetic brash tip of a developing device, in the case of making the temporarily recovering toner by a cleaning device, recovered from a developing area to the developing device. SOLUTION: The developing device 4 is provided with developer transporting body 5 for transporting the developer consisting of the toner and carrier into the vicinity of the image carrier 1, and an electrode member 17 disposed in the vicinity of the developer transporting body 5, on the upstream side of the image carrier 1 in the case of viewing it in the developer transporting direction. In the meantime, this device is allowed to impress bias on the developer transporting body 5 and the electrode member 17 so as to shift the toner from the developer transporting body 5 to the image part of the electrostatic latent image on the image carrier 1, and shift the toner from the electrode member 17 to the developer transporting body 5 in the image forming mode, and to impress bias on the developer transporting body 5 and the electrode member 17 so as to shift the toner from the image carrier 1 to the developer transporting body 5 and shift the toner from the developer transporting body 5 to the electrode member 17, in the toner recovering mode.

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 a dry process such as an electrophotographic method, and more particularly to an image forming apparatus having a toner reuse system.

[0002]

2. Description of the Related Art Techniques relating to a developing device and a cleaning device in an image forming apparatus adopting a dry process such as an electrophotographic system include the following, for example. [A] Japanese Unexamined Patent Publication No. 3-185477: An electrode member facing the sleeve is provided in a partial area in the circumferential direction of the developing sleeve to serve as a developer adjusting portion, and a magnetic field is formed there to hold a carrier and an electric field. A developing device that forms toner and attaches toner to the sleeve. [B] Japanese Patent Application Laid-Open No. 4-145474: An electrode member is provided in contact with the magnetic brush, and the toner is collected from the magnetic brush in the image area, and the toner is not collected from the magnetic brush in the non-image area. Magnetic brush cleaning device that switches the bias. [C] Japanese Unexamined Patent Publication No. 5-61387: A cleaning device that collects toner cleaned by a magnetic brush using a potential difference. [D] Japanese Unexamined Patent Publication No. 5-119607: A developing device in which an alternating electric field is formed in a space between plate-shaped members facing each other and a toner and a carrier in the space are vibrated and charged. [E] Japanese Patent Application Laid-Open No. 5-346736: A first oscillating electric field is formed between the plate-shaped member that is in contact with the upstream portion of the developing area on the sleeve and the sleeve, and a second oscillating electric field is generated between the photosensitive member and the sleeve. A developing device that creates an electric field.

[0003]

In an image forming apparatus such as a copying machine, a plain paper printer, and a facsimile using an electrophotographic method, from the viewpoint of reducing maintenance (toner collection work) and effectively using resources, There is a social demand for reuse. In such an image forming apparatus,
Toner in the developing device adheres to the image carrier (photoconductor) during development, and most of it moves (transfers) to a transfer material such as paper. At this time, as a method of reusing the toner remaining on the image carrier without being transferred, (1) the toner is once collected by a cleaning device, and then conveyed to a developing device through a conveyance path, and directly or mixed with replenishment toner. What is supplied to the developing device,
(2) The toner is held on the image carrier as it is and directly collected from the developing area to the developing device. (3) The toner is once collected by the cleaning device and then re-attached to the image carrier, and the toner is re-attached to the developing area. Directly from the developer to the developing device. The above (1) and (2) are techniques well known to those skilled in the art, and (3) is the content previously filed by the applicant.

When the above technique (3) is embodied, the developing device is required to have a function of adhering toner to the electrostatic latent image on the image carrier and a function of collecting the toner on the image carrier. . However, it is necessary to satisfy the conditions that are difficult to be compatible with each other, such as a magnetic brush on the sleeve having a small amount of toner for collection, and a magnetic brush having a large amount of toner for development being suitable.

The above-mentioned conventional techniques [A], [D], and [E] are techniques of the developing device alone, and [B] and [C] are techniques of the magnetic brush cleaning device alone. We will see if these satisfy the two functions described above.
In [A], a magnetic brush is formed only in a specific area of the developing sleeve and toner is attached to the sleeve. However, since there is no carrier in the developing area, it becomes difficult to collect the toner from the image carrier. . In [B] and [C], the toner is collected from the magnetic brush according to the situation, but the toner on the magnetic brush tends to be insufficient, and if the development is performed as it is, the efficiency is lowered. In [D], toner and carrier are vibrated on the sleeve to be charged before development, but this does not lead to improvement in cleaning function. [E]
Forms an oscillating electric field different from that in the developing area and improves the developing efficiency, but it does not lead to the cleaning function.

The present invention has been made in view of the above circumstances, and an object (problem) thereof is to collect toner once by a cleaning device and then re-attach it to an image carrier, and directly attach it from the developing area to the developing device. 1. An image forming apparatus having a toner collecting system for collecting toner according to claim 1, wherein: 1. To make sure that the toner on the image bearing member is easily attached to the tip of the magnetic brush of the developing device, to reliably collect the toner, and to improve the developing efficiency at the same time. By collecting the toner from the image carrier, it is possible to prevent the collected toner on the magnetic brush of the developing device from becoming excessive and scattering around the developing device (Claim 5). Even if high-density toner is collected from the image carrier, toner scattering and contamination of the device due to it are prevented.

[0007]

In order to achieve the above object, according to the present invention, in an image forming apparatus equipped with a developing means using a developer consisting of toner and carrier, a magnetic brush of a developer carrying body at the time of collecting toner. Toner can be removed electrically from the vicinity of the tip to make it easier to collect toner,
At the time of image formation, the collected toner is electrically supplied to the magnetic brush of the developer carrier to create a state where the developing efficiency is improved. Further, immediately after the toner is collected, the collected toner is electrically adsorbed to prevent the toner from scattering.

The image forming apparatus of the present invention comprises an image carrier and an electrostatic latent image forming means, a developing means, a transfer means and a cleaning means which are arranged around the image carrier, and the electrostatic latent image is formed. An electrostatic latent image is formed on the image carrier by the forming means, the electrostatic latent image is developed with toner by the developing means, and the toner image formed on the image carrier is transferred to the transfer material by the transfer means. ,
It operates in the image forming mode in which the residual toner on the image carrier after transfer is cleaned by the cleaning means and in the toner recovery mode in which the toner recovered by the cleaning means is transferred to the image carrier and the toner is recovered by the developing means. To do.

According to the first aspect of the invention, the developing means includes a developer carrying body for carrying the developer consisting of toner and carrier to the vicinity of the image carrier, and a developer carrying direction near the developer carrying body from the developer carrying direction. In the image forming mode, the toner is moved from the developer transporting member to the image portion of the electrostatic latent image of the image bearing member, and the electrode member is developed from the electrode member. To move the toner to the agent carrier,
Applying a bias to the developer carrier and the electrode member,
In the toner recovery mode, a bias is applied to the developer carrier and the electrode member so as to move the toner from the image carrier to the developer carrier and to move the toner from the developer carrier to the electrode member. And Further, in the invention of claim 2, in addition to the configuration of claim 1, a bias having a vibration component is applied to the electrode member in at least one of the image forming mode and the toner collecting mode.

According to a third aspect of the present invention, the developing means regulates a developer carrier that carries a developer composed of toner and carrier to the vicinity of the image carrier, and an amount of developer carried by the developer carrier. A developer regulating member is provided, and the developer regulating member can supply a bias, and the bias causes the toner to move from the developer regulating member to the developer transport body in the image forming mode, In the toner recovery mode, the potential is set such that the toner moves from the developer transport body to the developer regulating member.

In the invention of claim 4, the developing means conveys a developer consisting of toner and carrier to the vicinity of the image carrier, and a developer conveying direction near the developer conveying body when viewed from the developer conveying direction. In the image forming mode, there is an electrode member provided on the downstream side of the image carrier, and in the image forming mode, the developer carrier is used to move the toner from the developer carrier to the image portion of the electrostatic latent image of the image carrier. A bias is applied to the body, and in the toner recovery mode, the toner is moved from the image carrier to the developer carrier, and the toner is moved from the developer carrier to the electrode member. A bias is applied to the member.

According to a fifth aspect of the present invention, the developing means has a developer carrier for carrying a developer composed of toner and carrier to the vicinity of the image carrier, and an electrode member provided near the developer carrier. Then, in the toner recovery mode, a bias is applied to the developer carrier and the electrode member so that the toner is moved from the image carrier to the developer carrier and the toner is moved from the developer carrier to the electrode member. Then, after the toner recovery mode, a bias is applied to the developer transport body and the electrode member so as to move the toner from the electrode member to the developer transport body.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

[Embodiment 1] First, an embodiment corresponding to claims 1 and 5 will be described. FIG. 1 is a cross-sectional view of an essential part schematically showing a configuration example of an image forming apparatus in which the present invention is implemented. This image forming apparatus includes a drum-shaped image carrier (for example, a photoconductor (OPC) having an organic photoconductive layer) 1, and a charging roller 2, an image exposure system 3, and a periphery of the image carrier 1. Developing device 4, transfer roller 10, separation charger 1
1, a pre-cleaning charger 12, a cleaning device 13, and a discharge lamp 15 are arranged. In this image forming apparatus, the image bearing member 1 is uniformly charged by the charging roller 2, and the electrostatic latent image is formed on the image bearing member 1 by the electrostatic latent image forming means including the image exposure system 3 such as a laser scanning device. And the electrostatic latent image is developed with toner by the developing device 4, the toner image formed on the image carrier is transferred to the transfer material 9 by the transfer roller 10, and remains on the image carrier after transfer. There are two modes, an image forming mode in which toner is cleaned by the cleaning roller 14 of the cleaning device 13 and a toner recovery mode in which the toner collected by the cleaning device 13 is transferred to the image carrier 1 and the toner is collected by the developing device 4. It operates, and is controlled by the control part of FIG. 2 mentioned later.

FIG. 3 is a schematic sectional view showing a structural example of the developing device. The developing device 4 includes a developing sleeve 5, which is a developer carrier, a doctor blade 6 that regulates the amount of the developer carried by the developing sleeve 5, stirring members 7 and 8, an electrode member 17, and the like. The agitating members 7 and 8 mix and agitate the developer including the toner and the carrier. The developing sleeve 5 is made of a non-magnetic conductive member such as aluminum or stainless and has a permanent magnet that forms a plurality of magnetic poles inside. The developing sleeve 5 rotates in the direction of the arrow in the drawing to convey the developer, but the amount of the developer conveyed is restricted by the doctor blade 6. Doctor blade 6 is developing sleeve 5
A gap of about 0.2 to 1 mm is formed between the and. The electrode member 17 is provided at a position on the downstream side of the doctor blade 6 and close to the developing sleeve 5 on the upstream side of the image carrier 1 when viewed from the developer conveying direction of the developing sleeve 5, and is formed of a metal roller or plate. It has a shape. This electrode member 1
A bias different depending on the mode is applied to 7 by the power supply 18a. Further, a bias different depending on the mode is applied to the developing sleeve 5 by the power source 18b. The developer used is a two-component developer composed of a non-magnetic toner and a magnetic carrier, and the toner is negatively charged.

FIG. 2 shows a block diagram of a control system in the image forming apparatus of the present invention. The control unit 20 includes a central processing unit (CPU) including a known microcomputer, and a memory (RO that stores control programs and control data.
M, RAM), various control circuits, a clock, an input / output circuit (I / O), etc., and a high voltage power supply 18 for applying a bias to each unit according to a preset program, an image exposure timing, etc. It controls a laser control system 21, which controls the charging roller 10, a mechanism 22 that brings the charging roller 10 into and out of contact with the image carrier 1, a paper feeding mechanism 23 that supplies the transfer material 9, and a cleaning roller rotating mechanism 24 that controls the rotation of the cleaning roller 14. Although not shown, the rotation mechanism of the image carrier 1, the rotation mechanism of the developing sleeve 5 and the stirring members 7 and 8, the rotation mechanism of the fixing roller of the fixing device 16, and the turning on / off of the discharging lamp 15 are of course controlled. It is controlled by the unit 20. Further, key input information from the operation unit 25 and detection information from various sensors 26 are input to the control unit 20.

FIG. 4 is a flow chart for explaining the basic operation of the control system. When the apparatus is started, the rotation of the image carrier 1, the discharge from the separation charger 11 and the pre-cleaning charger 12, and the lighting of the discharge lamp 15 are started.
Next, charging by the charging roller 2, image exposure by the image exposure system 3, development by the developing device 4, transfer by the transfer roller 10, fixing by the fixing device 16, and cleaning device 1
An image forming mode in which each process of cleaning by 3 and a process of removing charge by the charge removing lamp 15 is performed, and a toner collecting mode in which the toner collected by the cleaning device 13 is transferred to the image carrier 1 and the toner is collected by the developing device 4 are executed. When the image formation is completed, the operation of each unit is stopped.

FIG. 5 is a flow chart for explaining an operation example in the image forming mode. In the following, a series of image forming processes will be described as a negative / positive process.
In the image forming mode, first, the charging roller 2 comes into contact and a bias is applied to the charging roller 2, so that the image carrier 1 which is a photoconductor (OPC) having an organic photoconductive layer is uniformly negatively charged. (-700V). Next, developing device 4
-500V to developing sleeve 5 and -80 to electrode member 17
0V, cleaning roller 14 of cleaning device 13
A +200 V bias is applied by the high voltage power supply 18 to rotate the cleaning roller 14 at a low speed. Next, the image carrier 1 is irradiated with laser light whose intensity is modulated by the image exposure system 3 according to the image signal, so that an electrostatic latent image is formed. At this time, the lowest solid black potential is -100V.

The latent image thus formed is developed by the magnetic brush formed on the developing sleeve 5 of the developing device 4 when passing through the developing area to form a toner image. On the other hand, a transfer paper (transfer material) 9 is fed from a paper feed mechanism (not shown), and a pair of upper and lower registration rollers (not shown) are provided between the image carrier 1 and the transfer roller 10 in synchronization with the leading edge of the image. And the toner image is transferred. The transfer roller 10 is +2 to match the timing.
A constant current of about 0 μA is supplied. After that, the transfer paper 9 is separated from the image carrier 1 and then the image is fixed through the fixing device 16 and discharged as a copy.

Although almost all the toner developed by the developing sleeve 5 is charged to the negative polarity, the transfer roller 10
Then, since the positive charge is supplied, the charge is injected from the transfer roller 10 into a part of the transfer residual toner to become the positive polarity toner. The pre-cleaning charger 12 (hereinafter referred to as PCC) supplies a negative corona to these toners, and the toners are recharged to the negative side. Since the positive bias is applied to the cleaning roller 14 while rotating, the transfer residual toner negatively charged by the PCC is collected by the cleaning roller 14. Further, the charge eliminating lamp 15 is turned on to erase the negative charge on the image carrier 1. Further, the image exposure is stopped after the exposure of one image is completed.

In this image forming mode, -500V is applied to the developing sleeve 5 and -800V is applied to the electrode member 17 by the high voltage power source 18 (18a, 18b), so that an electric field formed between them is generated. As a result, the toner attached to the electrode member 17 moves to the vicinity of the tip of the magnetic brush of the developing sleeve 5. Therefore, the amount of toner supplied to the image carrier 1 is increased and the developing efficiency is improved.

Next, FIG. 6 is a flow chart for explaining an operation example in the toner collecting mode. When the image formation is completed, the charging roller 2 is separated from the image carrier 1, the bias application is stopped, and −20 μA is supplied to the transfer roller 10. Also, + 300V to the developing sleeve 5,
+600 V is applied to the electrode member 17, −10 μA is supplied to the cleaning roller 14, and the cleaning roller 14 rotates at high speed. Then, this mode ends when the cleaning roller 14 makes almost one rotation.

When the rotation speed of the cleaning roller 14 and the bias are switched, the toner collected by the cleaning roller 14 is discharged to the image carrier 1. The discharged toner is conveyed to the developing area as the image carrier 1 rotates. At this time, the charging roller 2 is separated from the image carrier 1 so that the discharged toner does not adhere, and the surface potential of the image carrier 1 becomes about 0V. Also, the developing sleeve 5 has +300
Since V is applied, the electrostatic force directed from the image carrier 1 to the developing sleeve 5 acts on the toner on the image carrier in the developing area, and the impact force of the magnetic brush is also applied to remove the toner on the image carrier from the developing sleeve. Collect on the magnetic brush formed above.

In this toner recovery mode, a bias of +300 V is applied to the developing sleeve 5 and a bias of +600 V is applied to the electrode member 17 by the high voltage power source 18 (18a, 18b), and therefore the tip of the magnetic brush on the developing sleeve is applied. A part of the negatively charged toner in the above is generated by the electric field formed between the developing sleeve 5 and the electrode member 17,
Move to the electrode member 17. As a result, the amount of toner at the tip of the magnetic brush is reduced. On the other hand, since the surface potential of the image carrier 1 is almost 0V, the negatively charged toner on the image carrier moves to the magnetic brush to which a positive bias is applied. At this time, since there is no toner on the surface of the carrier and the exposed area is large, the toner on the image carrier easily adheres to that portion.

Further, in the flow chart of FIG. 4, if the image forming mode is not entered immediately after the toner is collected, +200 V is applied to the developing sleeve 5 to make the electrode member 1
By grounding 7 the toner on the electrode member may only be gradually returned to the magnetic brush. As a result, since the toner adheres to the magnetic brush over a wider area than when it is collected from the image carrier 1, it is possible to prevent the toner from accumulating on the electrode member 17 while preventing the scattering.

It should be noted that the numerical values shown in this embodiment are not limited, as long as the above-described action is produced. For example, when an image is formed by normal development (positive / positive process) using positively charged toner, the bias value naturally becomes appropriate and is applied to the electrode member 17. The applied voltage is also set to a value such that the toner moves from the electrode member 17 to the developing sleeve 5 in the image forming mode, and moves from the developing sleeve 5 to the electrode member 17 in the toner collecting mode.

[Embodiment 2] Next, an embodiment corresponding to claim 2 will be described. In this embodiment, the image forming apparatus has the same configuration as that of the first embodiment (FIGS. 1 to 3), except that the vibration component is superimposed on the bias applied to the electrode member 17.

More specifically, in the toner recovery mode, +300 V is applied to the developing sleeve 5 and DC is applied to the electrode member 17 by the high voltage power source 18 (18a, 18b).
In addition to component + 600V, AC component 2kHz, 500V (p
p) is applied. As a result, a part of the negatively charged toner from the tip of the magnetic brush on the developing sleeve to the vicinity of the root moves to the electrode member 17 due to the electric field formed between the developing sleeve 5 and the electrode member 17. . As a result, the amount of toner on the magnetic brush decreases around the tip, and the area where the carrier surface is exposed increases, so that the toner on the image carrier easily adheres to that portion.

In the image forming mode, -500V is applied to the developing sleeve 5 and -800V is applied to the electrode member 17 by the high voltage power source 18 (18a, 18b). Due to the electric field formed between the two, the toner attached to the electrode member 17 moves to the vicinity of the tip of the magnetic brush of the developing sleeve 5. Therefore, the amount of toner supplied to the image carrier 1 is increased and the developing efficiency is improved.

[Embodiment 3] Next, an embodiment corresponding to claim 3 will be described. In this embodiment, the developing device of the image forming apparatus shown in FIG. 1 has a structure as shown in FIG. The developing device 4 is composed of a developing sleeve 5 which is a developer carrier, a doctor blade 6 which regulates the amount of the developer carried by the developing sleeve 5, and stirring members 7 and 8, which are basically shown in FIG. Similar to the developing device, except that no electrode member is provided. That is, in this embodiment, at least a part of the doctor blade 6 is made of a magnetic or non-magnetic metal material, and a bias can be applied to the part from the high voltage power supply 18a. It has the same function as the member.

More specifically, in the toner collecting mode, +300 V is applied to the developing sleeve 5 and +60 is applied to the doctor blade 6 by the high voltage power supplies 18a and 18b.
When a bias of 0 V is applied, a part of the negatively charged toner on the tip of the magnetic brush on the developing sleeve 5 is doctored by an electric field formed between the developing sleeve 5 and the doctor blade 6. Move to blade 6. As a result, the amount of toner at the tip of the magnetic brush is reduced, and the area where the carrier surface is exposed increases, so that the toner on the image carrier easily adheres to that portion.

In the image forming mode, the developing sleeve 5 is -50 with respect to the high voltage power supplies 18a and 18b.
When a bias of 0 V and -800 V is applied to the doctor blade 6, the toner attached to the doctor blade 6 moves to the vicinity of the tip of the magnetic brush of the developing sleeve 5 due to the electric field formed between them. To do. Therefore, the amount of toner supplied to the image carrier is increased and the developing efficiency is improved.

[Embodiment 4] Next, an embodiment corresponding to claims 4 and 5 will be described. In this embodiment, the developing device of the image forming apparatus shown in FIG. 1 has a structure as shown in FIG. The developing device 4 is composed of a developing sleeve 5 which is a developer carrier, a doctor blade 6 which regulates the amount of the developer carried by the developing sleeve 5, stirring members 7 and 8, and an electrode member 17. 3 is similar to the developing device shown in FIG. 3, but the arrangement position of the electrode member 17 is different. That is, in this embodiment, the electrode member 17 is provided in the vicinity of the developing sleeve 5 and on the downstream side of the image carrier 1 when viewed from the developer transport direction, and biases different depending on the mode are applied.

More specifically, in the toner recovery mode, a bias of +300 V is applied to the developing sleeve 5 and a bias of +600 V is applied to the electrode member 17 by the high-voltage power supplies 18a and 18b, so that the image carrier 1 is biased. Since the surface potential is almost 0 V, the negatively charged toner on the image carrier moves and adheres to the magnetic brush of the developing sleeve 5 to which a positive bias is applied. Then, a part of the negatively charged toner attached near the tip of the magnetic brush is
The electric field formed between the developing sleeve 5 and the electrode member 17 moves the electrode member 17. As a result, the amount of toner at the tip of the magnetic brush is reduced, and the scattering of toner to the outside (especially outside the developing device) is reduced.

In the image forming mode, the developing sleeve 5 is -50 with respect to the high voltage power supplies 18a and 18b.
When a bias of 0 V and −800 V is applied to the electrode member 17, the toner adhered to the electrode member 17 moves to the vicinity of the tip of the magnetic brush of the developing sleeve 5 due to the electric field formed therebetween. However, accumulation of dirt on the electrode member 17 due to toner is prevented.

If the image forming mode is not entered immediately after the toner is collected, a bias of +200 V is applied to the developing sleeve 5 by the high voltage power supplies 18a and 18b.
By grounding the electrode member 17, only the toner on the electrode member 17 is gradually returned to the magnetic brush. As a result, the toner adheres to the magnetic brush over a wider area than when the toner is collected from the image carrier 1, so that the scattering can be prevented.

[0037]

As described above, in the image forming apparatus according to the first aspect, in the toner collecting mode, the developer carrier and the electrode member are biased so as to move the toner from the developer carrier to the electrode member. Is applied to reduce the toner concentration near the tip of the magnetic brush, the toner on the image carrier easily adheres to the magnetic brush. In the image forming mode, a bias is applied to the developer carrier and the electrode member so as to move the toner adhering to the electrode member to the tip of the magnetic brush in the toner collecting mode, thereby removing dirt on the electrode member, In addition, the development efficiency can be improved. As described above, the efficiency of development and toner recovery can be improved.

In the image forming apparatus according to claim 2,
In addition to the structure according to claim 1, by superposing the vibration component on the bias applied to the electrode member, the toner can be moved from the base side of the magnetic brush, and the toner that moves between the magnetic brush and the electrode member can be moved. The amount can be increased, and the efficiency of toner recovery from the image carrier and development on the image carrier can be improved.

In the image forming apparatus according to claim 3,
In the toner recovery mode, a bias can be supplied to the developer regulating member, and in the toner collecting mode, the developer regulating member regulates the layer of the developer carrying member to remove a part of the toner in the vicinity of the tip of the magnetic brush. Makes it easier to collect the toner on the image carrier. Further, in the image forming mode, the toner adhered in the toner collecting mode in the vicinity of the tip of the magnetic brush is supplied while the developer regulating member regulates the layer of the developer transport body, so that the developing efficiency can be increased.

In the image forming apparatus according to claim 4,
The electrode member is provided in the vicinity of the developer transport body and on the downstream side of the image carrier when viewed from the developer transport direction.
Since a bias is applied to the developer transport body and the electrode member so as to move the toner from the developer transport body to the electrode member,
In toner recovery mode, immediately after the toner is collected from the image carrier to the magnetic brush of the developer carrier, the toner is electrically attracted to the electrode member from the tip of the magnetic brush to prevent the toner from scattering around the developing device. can do.

In the image forming apparatus according to claim 5,
In the toner recovery mode, a bias is applied to the electrode member provided in the vicinity of the developer transport body so that the toner moves from the developer transport body to the electrode member, and the toner recovery mode is applied. After that, by applying a bias to the developer carrier and the electrode member so as to move the toner from the electrode member to the developer carrier, the toner is electrically collected from the magnetic brush of the developer carrier to the electrode member, After that, since the toner can be gradually returned from the electrode member to the magnetic brush, even if the high-density toner is collected from the image carrier in the toner collection mode, it is possible to prevent the toner from scattering and being contaminated.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an essential part schematically showing a configuration example of an image forming apparatus in which the present invention is implemented.

FIG. 2 is a block diagram showing a configuration example of a control system of the image forming apparatus shown in FIG.

FIG. 3 is a schematic sectional view showing a configuration example of a developing device of the image forming apparatus shown in FIG.

FIG. 4 is a flowchart illustrating a basic operation example of a control system.

FIG. 5 is a flowchart illustrating an operation example in an image forming mode.

FIG. 6 is a flowchart illustrating an operation example in a toner recovery mode.

FIG. 7 is a schematic cross-sectional view showing another configuration example of the developing device.

FIG. 8 is a schematic cross-sectional view showing still another configuration example of the developing device.

[Explanation of symbols]

 1: image carrier (photoreceptor) 2: charging roller 3: image exposure system (electrostatic latent image forming means) 4: developing device (developing means) 5: developing sleeve (developer carrier) 6: doctor blade ( Developer regulating member) 7, 8: Stirring member 9: Transfer material 10: Transfer roller (transfer means) 11: Separation charger 12: Pre-cleaning charger 13: Cleaning device (cleaning means) 14: Cleaning roller 15: Static elimination lamp 16: Fixing device 17: Electrode member 18 (18a, 18b): High-voltage power supply 20: Control unit 21: Laser control system 22: Charging / separating mechanism 23: Paper feeding mechanism 24: Cleaning roller rotating mechanism 25: Operation unit

Claims (5)

[Claims] 1. An image carrier, comprising: an image carrier; and an electrostatic latent image forming means, a developing means, a transfer means, and a cleaning means, which are arranged around the image carrier. An electrostatic latent image is formed on the surface, the electrostatic latent image is developed with toner by the developing unit, the toner image formed on the image carrier is transferred to a transfer material by the transfer unit, and the image carrier after transfer is formed. An image forming apparatus that operates in an image forming mode in which residual toner on the body is cleaned by a cleaning unit, and a toner collecting mode in which the toner collected by the cleaning unit is transferred to an image carrier and the toner is collected by a developing unit. In the above, the developing means is provided with a developer transporting body that transports a developer consisting of toner and carrier to the vicinity of the image carrier, and is provided near the developer transporting body on the upstream side of the image carrier as viewed in the developer transporting direction. Has an electrode member In the image forming mode, the toner is transferred from the developer carrier to the image portion of the electrostatic latent image on the image carrier, and the toner is transferred from the electrode member to the developer carrier. A bias is applied to the electrode member, and in the toner recovery mode, the toner is transferred from the image carrier to the developer carrier, and the toner is transferred from the developer carrier to the electrode member. An image forming apparatus, wherein a bias is applied to the electrode member. 2. The image forming apparatus according to claim 1, wherein a bias having a vibration component is applied to the electrode member in at least one of an image forming mode and a toner collecting mode. 3. An image carrier, which comprises an image carrier and an electrostatic latent image forming means, a developing means, a transfer means, and a cleaning means which are arranged around the image carrier. An electrostatic latent image is formed on the electrostatic latent image, the electrostatic latent image is developed with toner by the developing unit, the toner image formed on the image carrier is transferred to a transfer material by the transfer unit, and the image bearing after transfer is performed. An image forming apparatus that operates in an image forming mode in which residual toner on the body is cleaned by a cleaning unit, and a toner collecting mode in which the toner collected by the cleaning unit is transferred to an image carrier and the toner is collected by a developing unit. In the above, the developing means includes a developer transporting body that transports a developer consisting of toner and a carrier to the vicinity of the image carrier, and a developer regulating member that regulates the amount of developer transported by the developer transporting body.
The developer regulating member can supply a bias, and the bias causes the toner to move from the developer regulating member to the developer transport body in the image forming mode, and the developer transport body in the toner collecting mode. An image forming apparatus having an electric potential such that toner moves from a developer regulating member to the developer regulating member. 4. An image bearing member, and an electrostatic latent image forming unit, a developing unit, a transfer unit, and a cleaning unit disposed around the image bearing member. The electrostatic latent image forming unit includes the image bearing member. An electrostatic latent image is formed on the electrostatic latent image, the electrostatic latent image is developed with toner by the developing unit, the toner image formed on the image carrier is transferred to a transfer material by the transfer unit, and the image bearing after transfer is performed. An image forming apparatus that operates in an image forming mode in which residual toner on the body is cleaned by a cleaning unit, and a toner collecting mode in which the toner collected by the cleaning unit is transferred to an image carrier and the toner is collected by a developing unit. In the above, the developing means is provided on a developer transport body for transporting a developer consisting of toner and carrier to the vicinity of the image carrier, and on the downstream side of the image carrier as seen from the developer transport direction near the developer carrier. Has an electrode member In the image forming mode, a bias is applied to the developer carrying body so as to move the toner from the developer carrying body to the image portion of the electrostatic latent image of the image carrying body. An image forming apparatus, wherein a bias is applied to the developer transport body and the electrode member so as to move the toner from the body to the developer transport body and to move the toner from the developer transport body to the electrode member. 5. An image carrier, and an electrostatic latent image forming unit, a developing unit, a transfer unit, and a cleaning unit arranged around the image carrier, the electrostatic latent image forming unit comprising the image carrier. An electrostatic latent image is formed on the electrostatic latent image, the electrostatic latent image is developed with toner by the developing unit, the toner image formed on the image carrier is transferred to a transfer material by the transfer unit, and the image bearing after transfer is performed. An image forming apparatus that operates in an image forming mode in which residual toner on the body is cleaned by a cleaning unit, and a toner collecting mode in which the toner collected by the cleaning unit is transferred to an image carrier and the toner is collected by a developing unit. In the above, the developing unit has a developer transport body that transports a developer consisting of toner and a carrier to the vicinity of the image carrier, and an electrode member provided near the developer transport body, and in the toner recovery mode, From the image carrier A bias is applied to the developer transport body and the electrode member so as to move the toner to the developer transport body and move the toner from the developer transport body to the electrode member, and the toner is developed from the electrode member after the toner recovery mode. An image forming apparatus characterized in that a bias is applied to a developer carrier and an electrode member so as to move toner to the agent carrier.