JP2001290366A - Developing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a developing device where waste material generated when exchanging magnetic carrier can be decreased. SOLUTION: In this device, a developing sleeve 6, a first restricting member 8, a second restricting member 9a (a part of 9) and a toner containing part (not shown) are constituted as one attachable and detachable unit (developing sleeve assembly 4b) to and from a main body 4a of the developing device 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device and an image forming apparatus such as a copying machine, a facsimile, a printer, and the like provided with the developing device. The present invention relates to a developing device that takes in toner into the developer from the developing device.

[0002]

2. Description of the Related Art In a two-component developing device (hereinafter, referred to as a developing device) using a so-called two-component developer (hereinafter, referred to as a developer) containing a toner and a magnetic carrier, usually, the developing agent And only the toner is consumed, and the magnetic carrier is repeatedly used. However, as the magnetic carrier is used, a toner or a third additive is welded to the surface to be spent, or the magnetic carrier wears the surface coat layer. When the spent and abrasion progress to some extent, a phenomenon called so-called carrier adhesion that causes a magnetic carrier to adhere to a latent image carrier such as a photoconductor is caused, and toner is applied to a background portion (non-latent image portion) of the latent image carrier. Or cause a phenomenon called so-called background fouling. In order to avoid such carrier adhesion and background contamination, it is necessary to replace the magnetic carrier with a new one at the time when the magnetic carrier reaches the end of life due to the progress of the above-mentioned spent.

Therefore, conventionally, a developing sleeve, a stirring / mixing section for conveying toner supplied from a toner replenishing device of the image forming apparatus to the developing sleeve while stirring and mixing with a magnetic carrier by a stirring / conveying member, In a developing device including a regulating member for regulating the layer thickness of the component developer, there is known a developing device in which the developing sleeve, the stirring / mixing unit, and the regulating member are configured as a single detachable unit detachable from the developing device main body. ing. In this type of developing device, the developer is carried on a developing sleeve or housed in a stirring and mixing section. For this reason, by detaching the detachable unit including the developing sleeve and the stirring and mixing unit from the developing device main body, it is possible to separate and remove the magnetic carrier developing device main body from the end of its life. After the magnetic carrier is separated and removed in this way, a new detachable unit including the new magnetic carrier is attached to the developing device main body, so that the expired magnetic carrier can be replaced with a new one. it can. Further, after removing the magnetic carrier from the detached detachable unit, a new magnetic carrier may be charged into the detachable unit or the developing device main body to perform carrier exchange. In the carrier exchange as described above, the developing device main body can be continuously used, so that the cost can be reduced as compared with the case where the entire developing device is replaced.

[0004]

By the way, conventionally, the developing device does not include the stirring and mixing section as described above, and the developing device carries the developing agent from the toner supply port of the toner accommodating portion by the movement of the developer carried on the developer carrying member such as the developing sleeve. 2. Description of the Related Art A developing device that takes toner into an agent is known. In this type of developing device, a so-called self-toner concentration control is performed in which a proper amount of toner corresponding to the toner concentration is taken in from a toner supply port by its own movement for a developer carried on a developer carrying member. . In the developing device having such a configuration, since the stirring and mixing unit is not provided, a method of exchanging the magnetic carrier by exchanging a detachable unit including the agitating and mixing unit and the developer carrier cannot be adopted. However, the magnetic carrier has been replaced by replacing the entire developing device. However, such replacement requires replacement of the developing device casing and the like in addition to the magnetic carrier which has reached the end of its life, which causes a problem of increasing costs.

The present invention has been made in view of the above background, and an object of the present invention is to provide a developing device that takes in toner into a developer from a toner replenishing port by movement of the developer carried on the developer carrier. Another object of the present invention is to provide a developing device and an image forming apparatus that can perform carrier replacement at a lower cost than when the entire developing device is replaced.

[0006]

According to a first aspect of the present invention, a developer containing a toner and a magnetic carrier is carried by a magnetic force generated by a magnetic field generating means and moves endlessly in a predetermined direction. Developer carrying member, and a regulating member that regulates the layer thickness of the developer carried on the developer carrying member,
And a toner container having a toner supply port facing the developer carrier at a position upstream of the regulating member in the predetermined direction, wherein the developer carried on the developer carrier is provided. The developing device takes in the toner from the toner supply port into the developer, wherein the developer carrier is configured to be detachable from the developing device main body.

In this developing device, so-called self-toner density control is performed in which toner is taken into the developer from a toner supply port by the movement of the developer carried on the developer carrier. The inventor of the present invention has made intensive studies and found that a developing device that appropriately performs such self-toner density control necessarily has the following configuration. That is, the developer is moved to the developer carrier so that the movement speed of the developer near the toner supply port and the contact area between the developer and the toner can be appropriately changed according to the toner concentration of the developer. The structure is such that it is retained in the magnetic force area. Alternatively, even if the developer is moved to the outside of the magnetic force area, the developer is held around the developer carrier so that it can be returned to the magnetic force area by its own weight. As a result, the developer carrier can be removed from the developing device main body with all or most of the magnetic carriers in the developing device magnetically attached. For this reason, in this developing device in which the developer carrier is detachably attached to the developing device main body, by removing the developer carrier, all or most of the magnetic carrier inside the developing device can be removed from the developing device main body. Can be separated and removed. Then, the magnetic carrier that has reached the end of its life is removed from the removed developer carrier, and a new magnetic carrier is magnetically attached to the developer carrier,
If the developer carrier is attached to the developing device main body after being charged into the developing device main body, the magnetic carrier can be easily replaced. At this time, instead of reusing the removed developer carrier, a new developer carrier may be attached to the developing device main body. In the replacement of the magnetic carrier as described above, at least the developing device main body can be continuously used, and the carrier can be replaced at a lower cost than when the entire developing device is replaced.

However, there is a possibility that a very small amount of the magnetic carrier that has not been magnetically attached to the developer carrier at the time of detachment is left in the developing device main body, and that all the magnetic carriers cannot be reliably replaced.

Therefore, a second aspect of the present invention is the developing device according to the first aspect, wherein the developing device main body is configured to be detachable from the image forming apparatus.

In this developing device, all the magnetic carriers can be reliably replaced by performing the following operations. That is, first, the entire developing device is removed from the image forming apparatus, and then the developer carrier of the developing device is removed from the developing device main body. This removal exposes a portion of the developing device body that was not exposed before. When the developing device main body is tilted and shaken while holding it in such an exposed state, a very small amount of magnetic carrier left in the exposed portion can be removed from the developing device main body. . Then, after this, the magnetic carrier carried on the developer carrier is replaced, and then the developer carrier is attached, so that the magnetic carrier that has reached the end of its life is not left behind in the developing device main body. Can be reliably replaced.

By the way, in a developing device having a regulating member such as the developing device according to the present invention, when the developer carrying member is attached to and detached from the developing device main body, the gap between the developer carrying member and the regulating member is slightly changed. Therefore, it is necessary to perform a troublesome operation such as fine adjustment of the cap after the developer carrier is mounted. Further, in the case of performing self-toner concentration control as in the developing device according to the present invention, since the agitating and conveying member for actively rubbing the toner and the magnetic carrier is not provided, the amount of triboelectric charge of the toner may be insufficient. It is easy to cause soiling.

According to a third aspect of the present invention, in the developing device of the first or second aspect, the developer regulated by the regulation member is accommodated, and the accommodated developer is moved together with the developer carrier. The developer container that rubs the developer,
Provided downstream of the toner supply port in the predetermined direction,
The developer accommodating portion, the developer carrier, and the regulating member are configured as a single detachable unit that can be attached to and detached from the developing device main body.

In this developing device, the developer contained in the developer accommodating portion and the developer moving together with the developer carrier are located upstream of the regulating member in the direction of movement of the developer carrier. By rubbing, the toner in both developers is positively charged by friction. The developer containing the toner thus frictionally charged is transported to a development area downstream of the regulating member in the direction of movement of the developer carrier, and is used for development. Background dirt can be reduced. Further, in this developing device, the developer accommodating portion is included in the detachable unit, and when the detachable unit is detached, the developer contained in the developer accommodating portion is not left in the developing device main body, and the developer main body is not left behind. Can be separated and removed from In such a configuration, it is possible to substantially eliminate the remaining magnetic carrier that has reached the end of its life in the developing device main body. Further, in this developing device, not only the developer carrier and the developer container but also the regulating member are integrally configured as a detachable unit, so that the gap between the developer carrier and the regulating member can be finely adjusted. The magnetic carrier can be exchanged without performing such an operation.

By the way, claims 1 and 2 described above.
Or, in the developing device of 3, in order to remove the magnetic carrier which has reached the end of its life from the removed developer carrier, for example, vacuum is applied to the surface of the developer sleeve while manually rotating the developer sleeve as the developer carrier. A troublesome operation such as suctioning and removing the magnetic carrier by approaching the apparatus, scraping and removing the magnetic carrier by applying a rubber blade or the like to the surface of the developing sleeve is required.

Therefore, the invention of claim 4 is based on claims 1 and 2
Or the moving device moving endlessly in the predetermined direction, the magnetic field generating means being fixed so as not to move with the moving member, and attracting and holding the developer on the surface of the moving member by a magnetic force. Wherein the magnetic field generating means has the plurality of magnetic poles, and at least two of the magnetic poles are adjacent magnetic poles of the same polarity. .

In this developing device, for example, a moving member (sleeve or the like) in which a developer carrier moves in a predetermined direction, such as a conventional developing sleeve, and a magnetic field generating means (magnet) fixed so as not to move with the moving member. Rollers, etc.). This developer carrier has a characteristic configuration different from a conventional developing sleeve. Specifically, different magnetic poles are alternately formed on the magnet roller of the conventional developing sleeve so as to be adjacent to each other. When the different magnetic poles are adjacent to each other, a magnetic field line extending from one magnetic pole to the sleeve surface between the magnetic poles enters the other magnetic pole. Therefore, an effective magnetic force capable of attracting the magnetic carrier is maintained between the magnetic poles, and the magnetic carrier moved between the magnetic poles along with the sleeve surface is continuously restrained by the sleeve surface. On the other hand, the magnetic field generating means of the developer carrier of the developing device has the same magnetic poles adjacent to each other. A so-called repulsive magnetic field that repels the magnetic forces of the magnetic poles is formed between these magnetic poles, and the magnetic force at an approximately intermediate position between the two magnetic poles becomes almost zero.
For this reason, the magnetic carrier moved between these magnetic poles following the endless movement of the moving member such as the sleeve pipe is released from the binding force of the magnetic field generating means, and is smoothly separated from the surface of the moving member. In the present developing device provided with the developer carrier having such a configuration, if the following operation is performed,
The magnetic carrier can be easily removed from the developer carrier without using any special removing means such as the above-described vacuum means and rubber blade. That is, first, the moving member of the developer carrier removed from the developing device main body is moved endlessly by manual operation or the like, and the magnetic carriers magnetically attached to the moving member are sequentially moved to the position of the repulsive magnetic field. Then, the moved magnetic carrier may be sequentially separated from the surface of the moving member under the influence of the magnetic force of the repelling magnetic field.

However, in this developing device, the magnetic carrier (developer) once detached from the moving member of the developer carrying member due to the influence of the repulsive magnetic field during the developing operation is dropped from the developing device by gravity or the like, and the developing is performed. If the carrier amount in the apparatus is gradually reduced, the developing performance will eventually be reduced and the self-toner density control function will be lost.

According to a fifth aspect of the present invention, there is provided the developing device according to the fourth aspect, wherein the developer which detaches from the developer carrier due to a repulsive magnetic field formed by the adjacent magnetic poles having the same polarity is provided. An agent holding member for contacting and holding the developer in the vicinity of the developer carrier is provided.

In this developing device, the magnetic carrier (developer) detached from the moving member of the developer carrier due to the influence of the repulsive magnetic field is held near the developer carrier by the agent holding member. When the amount of the magnetic carrier held by the agent holding member increases in accordance with the endless movement of the moving member, the movement of the subsequent carrier before entering the repulsive magnetic field is hindered. Then, it is pushed out of the repulsive magnetic field by the subsequent carrier, and is magnetically attached to the moving member again under the influence of the magnetic force of the magnetic field generating means. In such a configuration, it is possible to prevent the magnetic carrier from falling off the developing device due to the influence of the repulsive magnetic field.

According to a sixth aspect of the present invention, there is provided an image forming apparatus comprising: a latent image forming means for forming a latent image on a latent image carrier; and a developing device for developing the latent image by adhering toner to form a toner image. In the above, the developing device is described in claims 1 and 2,
3, 4, or 5 developing devices are provided.

In this image forming apparatus, the carrier can be replaced at a lower cost than the case where the entire developing apparatus is replaced by the same operation as the developing apparatus of the first aspect.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an electrophotographic printer as an image forming apparatus will be described below. First, a basic configuration of the printer according to the present embodiment will be described. FIG. 1 is a schematic configuration diagram showing a developing device of the printer together with a photosensitive drum. In the figure, a photosensitive drum 1 as a latent image carrier is driven to rotate in a direction indicated by an arrow a (clockwise) in the figure by a driving unit (not shown). Around the photosensitive drum 1, a developing device 4, a charging unit (not shown), an optical writing unit, a charge removing unit, a transfer unit, a drum cleaning unit, and the like are arranged.

The photosensitive drum 1 carries an electrostatic latent image on its surface by, for example, the following well-known electrophotographic process. That is, the surface of the photosensitive drum 1 is neutralized when passing through the position facing the neutralizing means, and then moves to the position facing the charging device to be uniformly charged. Then, the optical writing unit performs an optical writing process based on the image information to carry an electrostatic latent image.

The electrostatic latent image carried on the photosensitive drum 1 as described above passes through a developing region which is a region facing the developing device 4 as the photosensitive drum 1 rotates, and The toner which electrostatically moves from above the developing sleeve 6 is adhered and developed into a toner image. This toner image moves to a transfer area, which is an area facing a transfer unit (not shown), as the photosensitive drum 1 rotates. And
In the transfer area, the sheet is superimposed on a transfer sheet (not shown) and is transferred onto the transfer sheet. The transfer paper is sent to a fixing device (not shown), where the toner image is fixed, and then discharged outside the printer.

After the residual toner remaining without being transferred is removed by the drum cleaning means, the surface of the photosensitive drum 1 which has passed through the transfer area is moved again to a position facing the charge removing means and the next image is formed. It is discharged for formation.

The developing device 4 disposed on the side of the photosensitive drum 1 has a casing 2 in which a toner accommodating portion 11 is formed. This toner storage unit 1 that stores toner T inside
Reference numeral 1 denotes an opening (toner supply port) facing the developing sleeve 6
Is formed. An agitator 5 that is driven to rotate clockwise in the figure by a driving unit (not shown) is provided inside the toner storage unit 11. The agitator 5 sends out the toner T stored in the toner storage unit 11 toward the passage 3 while stirring.
The length of the agitator 5 is desirably set to such an extent that the tip of the agitator 5 does not touch the staying developer Cb staying in the passage 3. With this setting, the magnetic carrier in the stagnant developer Cb is removed from the agitator 5.
Accordingly, it is possible to avoid carrier consumption caused by scraping the toner into the toner storage unit 11.

The bottom wall of the casing 2 has a toner storage 1
1 is provided with a toner sensor 10 for detecting the remaining amount of the toner T in 1. The toner sensor 10 converts the detection result of the remaining toner amount into an electric signal and transmits the electric signal to a control unit (not shown).

On the left side of the opening (toner supply port) of the passage 3 in the figure, a developing sleeve 6 as a developer carrier is disposed. The developing sleeve 6 is provided with a magnet roller as a magnetic field generating means fixed in a cylindrical non-magnetic pipe. It is designed to be rotationally driven in the direction b (counterclockwise).

Around the developing sleeve 6, a first regulating member 8 is provided between the front end of the developing sleeve 6 and the surface of the developing sleeve 6 at a position upstream of the position facing the photosensitive drum 1 (developing area) in the sleeve rotation direction. It is arranged so as to maintain a predetermined gap. The first regulating member 8 constitutes a part of the housing of the agent container 7. The housing of the agent container 7 includes a first regulating member and a cover 9, and one end of the cover 9 functions as a second regulating member 9a. This second regulating member 9
“a” holds a gap between the front end and the developing sleeve 6 that is larger than the gap between the developing sleeve 6 and the first regulating member 8. Further, as shown in FIG. 2, the passage 3 is formed by disposing the second regulating member 9a so as to maintain a predetermined gap and a length L with a part of the bottom wall of the casing 2. ing. Note that the agent container 7 and the second regulating member 9a may be formed as individual members.

The angle θ of the bottom surface of the passage 3 is desirably set so as to descend from the toner container toward the developing sleeve 6 as shown in FIG. With this setting, even if the magnetic carrier is moved from above the developing sleeve 6 into the passage 3 due to vibration, uneven magnetic force distribution of the magnet roller, scraping by the second regulating member 9a, etc., its own weight and its The developing sleeve 6 can be carried again by the synergistic action with the magnetic force of the magnet roller. As a result, it is possible to avoid carrier consumption caused by moving the developer Cb staying in the vicinity of the passage 3 into the toner container by its own weight.

The developer in the developer container 7 having an opening toward the developing sleeve 6 (hereinafter referred to as “container developer Cc”)
As shown by the arrow in FIG. 2, circulation is performed so as to rotate clockwise. Specifically, the developing sleeve 6
After moving in the sleeve rotation direction while rubbing with the developer Ca that rotates with the developer Ca, it is pushed in the opposite direction by being pushed by the subsequent contained developer Cc while being in contact with the first regulating member 8, and the like. To circulate. The agent container 7
Is formed so as to secure a sufficient space for circulating the developer Cc under the influence of the magnetic force of the magnet roller.

The toner storage unit 1 is controlled by the agitator 5.
The toner T sent out from 1 through the passage 3 toward the developing sleeve 6 is taken into the developer Ca that rotates with the developing sleeve 6.

The thickness of the layer of the developer Ca into which the toner T has been taken in this way is regulated when passing through the position facing the second regulating member 9a with the rotation of the developing sleeve 6. . The developer Ca, which is prevented from rotating together with the developing sleeve 6 due to this regulation, stays in the passage 3 or in the vicinity of the toner replenishing port thereof to become a staying developer Cb,
It is again carried by the developing sleeve 6 and passes through a position facing the second regulating member 9a. On the other hand, the developer Ca which has been moved to the position facing the developer container 7 without being restricted by the second regulating member 9a rubs against the above-mentioned developer Cc, exchanges the toner 5, performs the replacement of the developer 5, or Or a part of Cc. At this time, the toner T moves to the vicinity of the first regulating member 8 while frictional charging of the toner T inside is achieved by rubbing with the magnetic carrier.

The first regulating member 8 is arranged so as to maintain a gap smaller than the gap between the second regulating member 9a and the developing sleeve 6 between the first regulating member 8 and the developing sleeve 6, and rotates together with the developing sleeve 6. The layer thickness of the developer Ca is further reduced.
During this regulation, the internal pressure of the developer Ca that rotates with the developing sleeve 6 increases, and the frictional charging of the toner 5 inside the developer Ca is further promoted.

The developer Ca, which has been prevented from rotating together with the developing sleeve 6 due to the regulation by the first regulating member 8, is taken into the contained developer Cc and circulates in the developer containing section 7. On the other hand, the developer Ca that continues to rotate with the developing sleeve 6 without being regulated by the first regulating member 8 moves to the developing area.

A developing bias is applied to the developing sleeve 6 by a power source (not shown). By applying this developing bias, the developer C on the developing sleeve 6 is placed between the electrostatic latent image carried on the photosensitive drum 1 and the developing sleeve 6.
A development potential occurs such that the toner T in a is electrostatically moved toward the electrostatic latent image. Further, between the background portion (non-latent image portion) of the photoreceptor drum 1 and the developing sleeve 6, a development suppression potential is generated that suppresses the electrostatic movement of the toner T to the background portion. As a result, the developer Ca that has moved to the above-described development area by rotating with the developing sleeve 6 separates the toner T inside from the surface of the magnetic carrier and adheres to the electrostatic latent image. The adhesion causes the electrostatic latent image to be developed into a toner image.

In the developing device 4, the developer Ca having taken in a large amount of toner T from the toner supply port of the passage 3
Transfers a part of the taken-in toner T to the developer Cc contained in the developer container 7. In the above-described development area, the toner 5 in the developer Ca is consumed with the development. If the amount of toner taken in from the toner supply port exceeds the consumed amount, the toner concentration of the contained developer Cc gradually increases. Come. When the bulk of the stored developer Cc increases due to this increase, the frictional resistance between the subsequent developer Ca and the stored developer Cc is gradually increased, and the subsequent developer Ca is transferred from the agent storage unit 7 into the toner in the passage 3. A so-called thrusting phenomenon, such as pushing out to the supply port side, occurs. Also, a large amount of toner T
Developer Ca that has taken in the second
The amount regulated by the regulating member increases. As a result, the staying developer Cb staying in the passage 3 or near the toner supply port
Gradually increases, and the opening ratio of the toner supply port gradually decreases. Due to such a decrease in the aperture ratio, the contact area between the developer Ca and the toner T on the developing sleeve 6 at the position facing the passage 3 decreases. In addition, the staying developer Cb
Gradually decreases the staying movement speed with the increase. As a result, the amount of the developer Ca taken in with the developing sleeve 6 by the toner Ca gradually decreases.
That is, when the toner concentration of the developer Ca gradually increases due to the toner intake amount exceeding the toner consumption amount, the toner intake amount from the toner supply port 3 to the developer Ca gradually decreases. come.

When the toner intake amount gradually decreases and falls below the toner consumption amount, the toner concentration of the developer Ca that rotates with the developing sleeve 6 and the contained developer Cc decreases, and the volume of the developer Ca decreases. Will also decrease. Then, conversely, as a result of the decrease in the bulk of the stagnant developer Cb and the amount of the carrier, the opening ratio of the toner supply port closed by the stagnant developer Cb gradually increases, and the stagnant developer Cb also increases. The staying movement speed of the agent Cb gradually increases. Then, due to the synergistic effect of the increase in the aperture ratio and the increase in the staying movement speed, the amount of toner taken into the developer Ca from the passage 3 gradually increases, and the toner concentration of the developer Ca increases. Become like

As described above, in the developing device 4 of the present printer, the contact state between the developer Ca and the toner T is changed according to the toner concentration of the developer Ca entrained with the developing sleeve 6, and the change is caused by this change. The self toner density control for increasing or decreasing the amount of toner taken into the developer Ca is performed. By performing such self-toner concentration control, the developer C in the developing area can be provided even if a toner concentration sensor for detecting the toner concentration of the developer Ca is not provided.
The toner density a can be kept within a predetermined fluctuation range.

A shutter (not shown) is provided in the case of the developer container 7 of the developing device 4, and the initial setting of the magnetic carrier is performed as follows. That is, first, the shutter is opened, and the developing sleeve 6 is rotated while a so-called starting agent, in which the magnetic carrier and the toner T are mixed at a predetermined ratio in advance, is charged from the shutter into the agent container 7, and the developing sleeve 6 is rotated. 6 to obtain the developer Ca magnetically attached, the contained developer Cc, and the staying developer Cb. Next, toner T for replenishment may be charged into the toner storage unit 11.

Next, a characteristic configuration of the printer according to the present embodiment will be described. As shown in FIG. 2, the magnet roller 6a of the developing sleeve 6 has P1 (N pole), P1
2 (S pole), P3 (S pole), P4 (N pole), P5 (S pole)
Pole). Of these magnetic poles, P5 is disposed at a position facing the agent container 7 so as to promote circulation of the developer Cc in the agent container 7. P1 is the developer Ca in the development area.
So that can be restrained on the developing sleeve 6 with a desired strength.
It is arranged at a position facing the developing area. Also, P4
Is disposed at a position facing the toner supply port of the passage 3 so that the staying developer Cb can be restrained in the vicinity of the passage 3.

Here, what should be noted are the polarities and arrangement positions of P2 and P3. These magnetic poles are configured to have the same polarity (S-pole) and are arranged adjacent to each other.
P3 (S) to P4 (N pole), P4 (N pole) to P5 (S
P), P5 (S-pole) to P1 (N-pole), P1 (S-pole) to P
2 (N pole) are adjacent to each other with different poles,
P2 (S-pole) to P3 (S-pole) are adjacent to each other at the same polarity. Since a repulsive magnetic field is formed between P2 and P3 where the same poles are adjacent to each other, the magnetic force at the approximate intermediate position becomes almost zero. For this reason, P
The developer Cc that has moved between P2 and P3 no longer receives the magnetic force of the magnet roller 6a, and smoothly separates from the surface of the developing sleeve 6.

On the other hand, the casing 2 of the developing device 4
As shown in FIG. 5, an agent holding portion 2a as an agent holding member extending further downward from the lower portion of the passage 3 toward the lower side of the developing sleeve 6 is provided. The developer holding portion 2a is provided with a developing sleeve 6
Is formed so as to maintain a predetermined gap between
P2 and P3 are disposed at positions facing the agent holding portion 2a.

The developer Cc detached from the surface of the developing sleeve 6 due to the influence of the repulsive magnetic field falls by its own weight and is received by the developer holding portion 2a.
As shown in (1), it is held below the developing sleeve 6. When the amount of the developer Ca held in this manner increases, the gap between the developing sleeve 6 and the agent holding portion 2a is eventually closed, and the subsequent development that attempts to enter between P2 and P3 is performed. The movement of the agent Ca is inhibited. And P2
The developer Ca held in the agent holding portion 2a between P3
Is pushed out of the region of the repulsive magnetic field by the subsequent developer Ca, reaches the region within the magnetic force of P3, and
Again.

In a magnetic field generating means such as a magnet roller 6a having a plurality of magnetic poles disposed endlessly, if only one area is arranged so that magnetic poles of the same polarity are adjacent to each other, the number of magnetic poles must be increased. Be odd. On the other hand, when different magnetic poles are alternately arranged, the number of magnetic poles is always an even number.

FIG. 3 is a perspective view of the developing device 4. As shown in the figure, the developing device 4 includes a main body 4a and a developing sleeve assembly 4b as a detachable unit 4b detachably mounted on the main body 4a.

The main body 4a of the developing device 4 is
In addition to the toner accommodating section, agitator, and toner sensor (not shown) included in the casing 2 including a, a drive gear 16 and idle gears 15 and 14 rotatably supported on the side surface of the casing. The drive gear 16 receives a rotational driving force from a developing motor provided in a printer main body (not shown), rotates an agitator (not shown) provided in the toner storage section, and agitates the toner T in the toner storage section. Also, two idle gears 15, 1
The rotational driving force is transmitted to a sleeve gear described later via the fourth gear 4.

The developing sleeve assembly 4b detachably attached to the main body 4a includes a sleeve gear rotatably supported on the side surface of the cover 9 in addition to the first regulating member 8, the cover 9, and the developing sleeve 6. 13 and the like. The sleeve gear 13 includes a developing sleeve assembly 4 b and a main body 4.
In the state set at a, the idle gear 14 meshes with the idle gear 14, and receives the rotational driving force from the idle gear 14 to rotate the surface of the developing sleeve 6.

In the developing device 4 of the present printer, by performing the following operations, the magnetic carrier (developer Ca) which has reached the end of its life can be easily removed from the developing device 4. That is, first, the developing sleeve assembly 4b
Is removed from the main body 4a. As shown in FIG. 2, since the magnetic pole P4 is disposed at a position facing the passage 3 of the magnet roller 6a, when the developing sleeve assembly 4b is removed from the main body 4a, the magnetic pole P4 in the staying developer Cb is removed. The carrier can be securely magnetically attached to the developing sleeve 6 by the magnetic force of the magnetic pole P4. Therefore, even if the developing sleeve assembly 4b is removed from the main body 4a, the accumulated developer C
The magnetic carrier in b does not remain in the main body 4a. After removing the developing sleeve assembly 4b, the user holds the developing sleeve assembly 4b and places a container such as a trash can under the developing sleeve assembly 4b. Next, the sleeve gear 13 of the developing sleeve assembly 4b is rotated manually or by a dedicated motor, etc.
The developer Ca magnetically attached to the surface is sequentially moved to the position of the repulsive magnetic field, that is, to the lower side of the developing sleeve assembly 4b. Then, under the influence of the repelling magnetic field, the developer is separated from the surface of the developing sleeve 6 and dropped into the container 17 as shown in FIG. Such a developing sleeve 6
The magnetic carrier is transferred to the developing sleeve assembly 4b and thus the developing device if the magnetic carrier is carried out without the above-mentioned stored developer Cc in the toner storage section (not shown) in the developing sleeve assembly 4b. 4 can be easily removed.

The first regulating member 8 and the second regulating member 9a
It is necessary to precisely control the gap between the developing sleeve 6 and each other, for example, in a minute unit such as the order of μm, and the gap is strictly adjusted and fixed before shipment from the factory.
If these regulating members are separated from the developing sleeve 6 at the time of removing the magnetic carrier, re-adjustment of the gap requires a great deal of labor and time. However, in the present printer, these regulating members are configured integrally with the developing sleeve 6 as a detachable unit (developing sleeve assembly 4b), and are detachably attached to the developing sleeve 6. Therefore, it is not necessary to perform a troublesome work of finely adjusting the gap after setting these regulating members in the main body 4a.
The carrier exchange operation can be facilitated and the time can be reduced.

As described above, during the developing operation, the developing sleeve 6 is opposed to the developer holding portion 2a, and the developer Ca once separated from the surface of the developing sleeve 6 by the influence of the repulsive magnetic field is removed. It is held around the developing sleeve 6 by the holding portion 2a (FIG. 2). For this reason, the separated developer Ca does not drop to a region outside the magnetic force beyond the magnetic force of the magnet roller 6a, and the consumption of the magnetic carrier due to such a drop can be avoided.

Since the agent holding portion 2a is formed integrally with the casing 2 of the main body 4a, the developing sleeve assembly 4
When b is removed from the main body 4a, the agent holding portion 2a and the developing sleeve assembly 4b are separated. Therefore, when the magnetic carrier is removed, as shown in FIG. 4, the agent holding portion 2a is not positioned below the developing sleeve 6, and the magnetic carrier removed from the surface of the developing sleeve 6 is not used. (Developer Ca) can be easily dropped into the container 17.

Further, the second step for forming the repulsive magnetic field is performed.
The two magnetic poles (P2, P3) are arranged so as not to face the agent container 7. For this reason, the developer Ca detached from the surface of the developing sleeve 6 due to the influence of the repulsive magnetic field does not need to be accommodated in the agent accommodating section 7, so that the operation of removing the magnetic carrier can be easily facilitated.

As described above, according to the printer of the present embodiment, the magnetic carrier whose life has expired can be replaced with a new magnetic carrier without discarding the developing device 4.

In this embodiment, the printer having the developing device 4 for forming the repulsive magnetic field has been described. However, the present invention can be applied to an image forming apparatus having a developing device which does not generate the repulsive magnetic field. It is. In such a developing device, the detachable unit such as the developing sleeve assembly 4b may be disposed as a disposal member together with the magnetic carrier. Even if it is discarded in this way, the developing device main body such as the main body 4a can be reused, and the number of discarded members can be reduced.

[0056]

According to the first, second, third, fourth, fifth and sixth aspects of the invention, there is an excellent effect that the carrier can be replaced at a lower cost than when the entire developing device is replaced.

In particular, according to the second aspect of the invention, the magnetic carrier which has reached the end of its life is not left in the developing device main body.
There is an excellent effect that all magnetic carriers can be reliably replaced.

In particular, according to the invention of claim 3, there is an excellent effect that background contamination due to insufficient charging of the toner can be reduced. Further, there is an excellent effect that it is possible to almost completely remove the magnetic carrier whose life has expired from being left in the developing device main body. Also, there is an excellent effect that the magnetic carrier can be exchanged without performing a troublesome operation such as fine adjustment of the gap between the developer carrier and the regulating member.

In particular, according to the invention of claim 4, an excellent effect that the magnetic carrier can be easily removed from the developer carrying member without using any special removing means such as a vacuum means or a rubber blade. There is.

According to the fifth aspect of the present invention, the magnetic carrier is prevented from dropping from the developing device due to the influence of the repulsive magnetic field. There is an excellent effect that it is possible to avoid the disappearance of.

According to the sixth aspect of the present invention, it takes time and effort to remove the carrier by suction with a vacuum or the like, remove the carrier by scraping with a blade or the like, and finely adjust the gap between the developer carrier and the regulating member. There is an excellent effect that the carrier of the developing device can be exchanged without performing the operation. Also, there is an excellent effect that the carrier can be replaced at a lower cost than when the entire developing device is replaced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a developing device of a printer according to an embodiment together with a photosensitive drum.

FIG. 2 is a sectional view showing a configuration around a developing sleeve of the developing device.

FIG. 3 is a perspective view of the developing device.

FIG. 4 is an explanatory diagram for explaining an operation of removing the magnetic carrier in the developing device.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 photoconductor drum 2 casing 3 passage 3a toner supply port 4 developing device 5 agitator 6 developing sleeve (developer carrier) 6a magnet roller (magnetic field generating means) 7 agent container 8 first regulating member 9 cover 9a second regulating member REFERENCE SIGNS LIST 10 toner sensor 11 toner storage section (development substance storage section) 13 sleeve gear 14, 15 idle gear 16 drive gear 17 container Ca (co-rotating) developer Cb staying developer Cc storage developer T toner (development substance)

Claims (6)

[Claims] A developer carrying a developer containing a toner and a magnetic carrier by a magnetic force generated by a magnetic field generating means and moving endlessly in a predetermined direction; and a developer carrying the developer carried on the developer carrying body. A regulating member for regulating a layer thickness, and a toner accommodating portion accommodating toner therein and having a toner supply port facing the developer carrier at an upstream side of the regulating member in the predetermined direction. In a developing device for taking in toner into the developer from the toner supply port by movement of the developer carried on a carrier, the developer carrier is configured to be detachable from a developing device main body. . 2. The developing device according to claim 1, wherein said developing device main body is configured to be detachable from said image forming apparatus. 3. The developing device according to claim 1, wherein the developer containing the developer regulated by the regulating member is rubbed with the developer moving together with the developer carrier. A container is provided downstream of the toner replenishing port in the predetermined direction, and the agent container, the developer carrier, and the regulating member are configured as a single detachable unit that can be attached to and detached from the developing device main body. A developing device. 4. The developing device according to claim 1, wherein the movable member is fixed so as not to move together with the movable member and moves the developer by magnetic force. The developing carrier is constituted by the magnetic field generating means attracting and supporting the surface, the magnetic field generating means having the plurality of magnetic poles, and at least two of the magnetic poles having the same magnetic pole adjacent to each other. A developing device, characterized in that: 5. The developing device according to claim 4, wherein the developer comes into contact with the developer which is to be separated from the developer carrier due to a repulsive magnetic field formed by the magnetic poles of the same polarity adjacent to each other. A developer holding member for holding the developer in the vicinity of the developer carrier. 6. An image forming apparatus comprising: a latent image forming means for forming a latent image on a latent image carrier; and a developing device for developing the latent image by attaching toner to form a toner image. An image forming apparatus provided with the developing device according to claim 1, 2, 3, 4, or 5.