JP3440970B2 - Rotary developing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary developing device used in an image forming apparatus such as a copying machine, a facsimile, a printer or the like.

[0002]

2. Description of the Related Art Heretofore, as a rotary developing device of this type, a developing device unit having a plurality of developing devices arranged around a rotation axis is rotated about the rotation axis so that an arbitrary developing device is rotated. , A developing port in which a developer carrying member housed in the developing device is exposed is moved to a developing position facing the image carrying member,
It is known that the magnetic force of a magnetic field generating means provided inside the developer carrying member develops the developer carried on the developer carrying member.

[0003]

However, in this type of rotary developing device, since the developing device unit is repeatedly rotated, the developing device is placed at a rotation position such that the developer exists above the developer carrying member. When there is a unit, the developer tries to move downward in the developing device due to the influence of gravity. And since this developer has some fluidity,
Attempts to move laterally toward the end of the developer carrying member in the longitudinal direction.
Here, there is usually no magnetic field generating means at the end portion in the longitudinal direction, and the magnetic force of the magnetic field generating means is not exerted, so if the developer laterally moves around the end portion in the longitudinal direction. However, it is no longer possible to control the developer with magnetic force in the magnetic field generating means. For this reason, when the developing device unit is rotated to set the developer carrying member to the developing position facing the latent image carrying member and the developing operation is started, the developer remaining around the end portion in the longitudinal direction remains. However, due to the movement of the developer carrier accompanying the developing operation, the developer carrier is conveyed to the developing port at once. Then, the developer conveyed to the developing port at one time is
When the developer carrying member tries to return to the inside of the developing device again with the movement of the developer carrying member, it cannot be completely returned from between the developer carrying member forming the developing port and the developer carrying member, and the developer overflows from the developing port. There was a problem that it would occur.

Further, for example, in a rotary developing device in which side seals are provided at both ends of a developing port of a developing device as a developer scattering preventing member for preventing developer scattering from the both ends, the developer overflows. Due to the above, the overflowed developer may impose an excessive load on the side seal, which may damage the side seal. Further, the developer is pressed by the high pressure when the developer is forced to enter between the developing port and the developer carrier, and the heat generated at this time fixes the developer on the developer carrier. However, when the developer carrying member is packed with the adhered developer, there is a risk of causing a locking phenomenon of the developer carrying member that prevents rotation of the developer carrying member, so-called development lock. there were.

The present invention has been made in view of the above problems, and an object of the present invention is to develop a developer when the developer moves inside the developing device as the developing device unit rotates. It is an object of the present invention to provide a rotary developing device capable of preventing the above-mentioned agent overflow from occurring by preventing the agent carrier from getting around the edge portion.

[0006]

In order to achieve the above object, the invention of claim 1 rotates a developing device unit having a plurality of developing devices arranged around a rotation axis about the rotation axis. Then, the arbitrary developing device is moved to a developing position where the developing port in which the developer carrying member accommodated in the developing device is exposed faces the latent image carrying member, and the magnetic field provided inside the developer carrying member is moved. In a rotary developing device for developing with a developer carried on the developer carrying member by the magnetic force of the generating means,
The development is carried out from at least one of the developer carrying body supports which support the developer carrying body on the longitudinal end side so as to cover the outer peripheral portion of the developer carrying body which is not exposed from the developing port of the developing device. An end portion covering member configured to project at a predetermined width toward the central portion side in the longitudinal direction of the agent carrier is disposed so as to come into contact with a magnetic brush formed on the developer carrier by the magnetic force of the magnetic field generating means. It is characterized by having done.

In the invention of claim 1, from at least one of the developer carrier supports which supports the developer carrier at the end portion in the longitudinal direction, the developer carrier has a predetermined width from the central portion side in the longitudinal direction. Due to the protruding end cover member, the outer peripheral portion of the developer carrier not exposed from the developing port of the developing device comes into contact with the magnetic brush formed on the developer carrier by the magnetic force of the magnetic field generating means. As described above, the gap between the developer carrying member and the end portion covering member is closed by the magnetic brush of the developer formed by the magnetic force of the magnetic field generating means. Therefore, unlike the case where the end portion covering member is not provided, when the developer carrier is positioned at a rotation position where the developer is present above the developer carrier by the rotation of the developing device unit, The developer having fluidity moves downward in the developing device by its own weight, and further, on the developer carrying member in a direction orthogonal to the developer conveying direction, that is, the developer is Even if the developer tries to move to both ends in the longitudinal direction, the developer does not go around the end portion of the developer carrier through the gap.

In particular, the invention of claim 2 is the rotary type developing device of claim 1, wherein the gap between the end portion covering member and the developer carrying member is developed between the developer carrying member and the latent image carrying member. It is characterized in that it is set larger than the gap.

According to the second aspect of the present invention, the gap between the end portion covering member and the developer carrying member is set to be larger than the developing gap between the developer carrying member and the latent image carrying member. This prevents the developer from aggregating in the gap. As a result, unlike the case where the gap is set smaller than the developing gap, the developer agglomeration does not occur in the gap, so that the packing of the gap caused by the developer agglomeration can be prevented and the packing can be formed. Since the friction between the developer and the end portion covering member is reduced, it is possible to prevent the developer from being fixed to the developer carrying member side due to frictional heat.

Here, when the rotary developing device is repeatedly rotated, after passing through the developer regulating member for regulating the magnetic brush made of the developer carried on the developer carrying member to a predetermined height or amount. Because of its fluidity,
There is a possibility that the swelling of the developer may occur at the end portion of the developer bearing member when the developer carrier is moved toward the end portion. If the developer is conveyed to a portion facing the latent image carrier while the swelling of the developer is generated, the side seal may be damaged when the side seal is provided.

Therefore, in particular, in the invention of claim 3, in the rotary developing device of claim 1, the protrusion width of the end portion covering member toward the central portion side in the longitudinal direction of the developer carrier is
The magnetic brush made of the developer conveyed on the developer carrying member is set to be smaller on the downstream side than on the upstream side in the developer conveying direction of the developer regulating member that regulates the magnetic brush to a predetermined height or amount. It is characterized by having done.

According to the third aspect of the present invention, even if the developer passing through the developer regulating member tries to move to the end side of the developer carrying member by the repeated rotation of the rotary developing device, the end coating is performed. Since the projecting width of the member is smaller on the downstream side of the developer regulating member than on the upstream side in the developer conveying direction, compared to the case where the projecting width is the same before and after passing through the developer regulating member. The escape path for the developer in the longitudinal direction of the developer carrier can be secured.

According to a fourth aspect of the present invention, in the rotary developing apparatus according to the first aspect in which the developer carrying member is rotatable in the forward and reverse directions, the developer carrying member is conveyed on the developer carrying member before starting the development. The magnetic brush composed of the developer stays in the gap between the end covering member and the developer carrier in the vicinity of the upstream side in the developer transport direction with respect to the developer regulating member that regulates the magnetic brush to a predetermined height or amount. A control means is provided for controlling the developer carrier to rotate in a direction opposite to the direction in which the developer carrier is conveyed so as to convey the developer in a direction opposite to the developer conveying direction. It is what

In a fourth aspect of the present invention, the developer carrying member housed in the developing device is controlled by the control means in a direction opposite to the rotating direction of the developer carrying member at the time of development before starting the development. Control to rotate. By this control, the end coating in the vicinity of the upstream side in the developer transport direction of the developer regulating member that regulates the magnetic brush made of the developer transported on the developer carrying member to a predetermined height or amount. The developer staying in the gap between the member and the developer carrying member is returned to the developer stirring unit side of the developing device by the carrying magnetic force of the magnetic field generating means when the developer carrying member rotates in the reverse direction, The degree of agglomeration of the developer staying in is relaxed.

In particular, the invention of claim 5 is the rotary developing apparatus according to claim 1, wherein the magnetic field generating means disposed inside the developer carrying member or the end of the developer carrying member is magnetic. It is characterized in that a member is provided.

In the invention of claim 5, it is provided at the end portion of the magnetic field generating means or the end portion of the developer carrying member, that is, the portion where the magnetic force is usually higher than the other portions. The magnetic member reduces the magnetic force at the end of the magnetic field generating means and reduces the amount of developer attracted by the magnetic force to the end of the developer carrier.

[0017]

DETAILED DESCRIPTION OF THE INVENTION An embodiment in which the present invention is applied to a color electrophotographic printer (hereinafter referred to as a printer) which is an image forming apparatus will be described below. FIG. 1 is a schematic configuration diagram of a printer according to this embodiment. First, an outline of the entire printer will be described. In FIG. 1, a photosensitive drum 1 serving as a latent image carrier is uniformly driven by a charging charger 2 serving as uniform charging means while being rotationally driven in the direction of arrow A, and then image information is generated by a laser optical device 3. Scanning exposure is performed on the basis of the above to form an electrostatic latent image on the surface. Here, the image information to be exposed is image information of a single color obtained by separating a desired full-color image into color information of yellow, magenta, cyan, and black. The electrostatic latent image formed on the photoconductor drum 1 is developed by a rotary developing device 4 described later with yellow, magenta, cyan, and black toners as predetermined developers, respectively, and thus, on the photoconductor drum 1. An image of each color is formed on.

Each color image formed on the photoconductor drum 1 is formed on the intermediate transfer belt 5 which rotates in the direction of arrow B in the figure in synchronization with the photoconductor drum 1 for each color of yellow, magenta, cyan and black. The primary transfer charger 6 sequentially performs the superimposed transfer. The yellow, magenta, cyan, and black images that are superposed on the intermediate transfer belt 5 are transferred from the automatic paper feed cassette 7 for double-sided copying or the manual paper feed tray 7a through the paper feed rollers 8 and 8a and the registration rollers 9. The secondary transfer charger 11 collectively transfers the image onto the transfer sheet 10 as a transfer material that has been conveyed to. After the transfer is completed, the transfer paper 10 is transported on a transport belt 15 as a transfer material transport device arranged below the rotary developing device 4, the toner image is fixed by the fixing device 12, and the full-color print is discharged to the outside of the device. It

The toner on the photoconductor drum 1 that has not been transferred onto the intermediate transfer belt 5 is removed by the photoconductor cleaner 13.
Is removed from the photosensitive drum 1 by the
The toner on the intermediate transfer belt 5 that has not been transferred onto the
It is removed from the intermediate transfer belt 5 by the intermediate transfer belt cleaner 14.

Next, the rotary developing device according to this embodiment will be described. 2 is an exploded perspective view of the developing device, FIG.
FIG. 3 is a sectional view showing an internal structure of a developing device unit 40 of the developing device. In FIG. 2, the rotary developing device has a developing device for each of four colors, for example, black, cyan, yellow, and magenta formed therein, and has a substantially cylindrical outer periphery that is attached rotatably around the central axis in the printer body. And a four toner container 41, 42, 43, 44 corresponding to each developer in a one-to-one correspondence and containing toners of black, yellow, magenta, and cyan, respectively. A toner container unit 45 that is attached so as to be substantially coaxial with the front side in the direction of the central axis with respect to 40, and rotates integrally with the developing unit 40 around the central axis, and the developing unit 40 and the toner container. The unit 45 (hereinafter referred to as a revolver developing unit) can be slid on the printer body substantially parallel to the central axis line while being carried. The volume table 46, and a cover 47 provided so as not to rotate in the housing base before the support plate 48 so as to cover the toner container unit 45.

The revolver developing unit is provided with a receiving table 46.
Of the developing device unit 40 is supported by, for example, two support rollers 49 rotatably attached to the front supporting plate 48 of the developing device unit 40, and the disk-shaped rear end wall 51 of the developing device unit 40 is supported. The central axis 52 of the tip taper protruding from the center
Is rotatably supported by a central shaft insertion hole 54 formed in the rear plate 53 of the main body, so that the rotation axis of the printer main body is substantially the same as the rotation axis of the photosensitive drum 1 as shown in FIG. They are positioned so as to be parallel to each other in the same horizontal plane and are rotatable.

First, the mechanism for rotatably supporting the revolver developing device unit 40 will be described with reference to FIG. In FIG. 2, the accommodation base 46 includes the front support plate 48, the rear support plate 55, and a side cover 59 having front and rear end portions fixed to both support plates and reinforced by connecting rods 56, 57 and 58. Have. The front support plate 48 has an insertion hole 60 into which the revolver developing device unit 40 can be inserted.
In addition to the support roller 49, a motor 61 for driving the toner replenishing roller provided in the toner container unit 45 and a gear train driven by the motor 61 are attached. An intermediate plate 63 is attached to the connecting rods 56 and 57 in the vicinity of the rear support plate 55, and a positioning pin 63b that fits into a positioning hole 63a formed in the rear plate of the main body projects from the intermediate plate 63. It is set up. A base end portion of a bracket 64 holding a rotary positioning roller 66 is swingably attached to a positioning pin portion between the middle plate 63 and the rear support plate 55. Then, the bracket 64 fits the rollers 66 into the recesses 65 formed at predetermined positions (a total of four positions corresponding to each of the four developing devices in the present embodiment) on the peripheral surface of the developing device unit rear end wall 51. A spring 67 is biased in the direction.

The front plate 68 of the main body is formed with an insertion hole 69 or the like into which the receiving base 46 carrying the revolver developing device unit 40 can be inserted, and between the front side plate 68 and the rear plate 53 of the main body. Upper and lower guides 70 and 71 for slidably supporting the accommodation base 46 are hung. Guided portions 72 and 73 are provided at the upper end and side portions of the side cover 59 of the storage table 46, respectively, as the receiving base portion guided by these guides 70 and 71, and the guided portion 73 on the side portion thereof is provided. A guide pin groove 75 into which the guide pin 74 planted upward in the guide 71 is inserted is formed on the lower surface of the guide 71. This pin groove 75
Is a revolver developer unit at a predetermined position relatively close to the photoconductor drum 1 when the storage base 46 is released from the photoconductor drum 1 at the time of inserting or pulling out of the photoconductor drum 1 into or from the printer body. In order to guide 40, only a predetermined portion on the front side is bent from the middle so that it is closer to the photosensitive drum 1 than the rear portion.

In the support mechanism of the revolver developing device unit 40 described above, when the accommodating base 46 is inserted into the main body, the tapered tip end of the positioning pin 63b protruding from the intermediate plate 63 is inserted into the printer main body. Immediately before the completion of the insertion, the positioning holes 63a of the rear plate 53 of the main body are inserted into the positioning holes 63a.
Accurately position 3 in the body. In addition, the accommodation table 46
In the pulled-out state, the rear end portion of the revolver developing device unit 40 supported by the rear plate 53 of the accommodating base 46 has a tapered central axis 52 immediately before the main body of the accommodating base 46 is completely inserted.
Are gradually lifted from the rear support plate 55 at the time of completion of the insertion. Then, the front support plate 48 of the accommodation table 46 is fixed to the front plate 68 of the main body with a screw 76 or the like after the insertion of the accommodation table 46 into the main body is completed. As a result, the revolver developing device unit 40 has its front end supported by the support roller 49 of the housing stand front support plate 48 accurately positioned on the main body.
Further, the rear end portion is rotatably positioned on the main body rear side plate 53 through the central shaft 52, and the rear end plate 53 is rotatable.

Further, in a state in which the accommodation table 46 is pulled out to the front side of the apparatus main body, the front end wall 50 of the developing unit 40 is rotatably supported by the support roller 49 of the accommodation table front support plate 48,
Further, since the rear end wall 51 of the developing device unit 40 is rotatably supported by the rear support plate 55 of the accommodating base and the revolver developing device unit 40 can be rotatably held, the revolver developing device unit 40 described later is appropriately rotated. It is possible to favorably perform the developer replacement operation for each developing device in this pulled out state. It should be noted that, in order to allow the revolver developing device unit 40 to rotate more smoothly in this pulled-out state, the rear support plate 55 side of the accommodating base may be supported by using the same support roller as the front side.

A revolver drive gear 78, which is driven by a revolver rotation motor (not shown) such as a stepping motor, is attached to the main body rear side plate 53 to drive the revolver developing unit 40 to rotate. This meshes with the revolver input gear 79 having substantially the same diameter as that of the rear end wall 51 fixed to the rear surface of the rear end plate of the developing device unit 40 by screws or the like, and rotationally drives the revolver developing device unit 40. There is.

Next, the main body of the developing device unit 40 will be described with reference to FIG. In FIG. 3, the developing device unit 40 includes the partition wall provided between the front and rear end walls 50 and 51 having the substantially disk shape described above. This partition wall has a hollow cylindrical portion 82 into which a cylindrical black toner bottle containing black toner can be inserted, and a partition wall extending radially from the hollow cylindrical portion 82 so that the space around the hollow cylindrical portion 82 is substantially in the circumferential direction. Developing device casing portion 8 divided into four developing chambers of the same type
3, 83C, 83M, and 83Y. Each of the developing chambers contains a carrier as a developer and a two-component developer including toner of each color. In the illustrated example, the developing position facing the photoconductor drum is the developing chamber of the black developing device containing the black toner and the carrier, and in the counterclockwise order in the figure, the yellow developing device containing the yellow toner and the carrier is arranged. A developing chamber, a developing chamber of a magenta developing unit containing magenta toner and a carrier, and a developing chamber of a cyan developing unit containing cyan toner and a carrier.

Since the internal structure of each of the four developing chambers is exactly the same, the internal structure will be described below by taking the black developing chamber at the developing position in FIG. 3 as an example, and the internal structures of the other developing chambers will be described. As the reference numerals of the members to be used, yellow, magenta,
In order to distinguish the cyan developing chambers, reference numerals with Y, M, and C suffixes are shown in the drawing, and the description thereof is omitted.

In the black developing device in the developing position in the drawing, an opening portion facing the photosensitive drum 1 is formed in the developing device casing portion 83, and a part thereof is exposed through the opening portion in the developing chamber. A developing roller 84 is provided. Further, in the developing chamber, a doctor blade 85 that regulates the amount of developer carried by a developing roller 84 and is conveyed to a portion facing the photosensitive drum 1, and the development regulated by the doctor blade 85 and held in the developing chamber An upper conveying screw 86 for conveying a part of the developer from the rear to the front along the central axis direction and a guide 87 thereof, and a stirring paddle 88 for stirring the developer in the developing chamber are provided. The stirring paddle 88 has a plurality of developer discharge holes 89a across the width of the developing roller 84.
And a plurality of stirring plate portions 90 radially extending from the peripheral surface of the hollow cylindrical portion 89. The hollow cylindrical portion 89 is provided with the agitating plate portion 90 radially extending from the peripheral surface thereof. A lower carrying screw 91 for carrying the developer in the opposite direction to the screw 86 is housed. In the developing device casing portion below the lower transport screw 91, when the developer is replaced due to the deterioration of the development in the developing chamber, the developer is used as a discharge port for the deteriorated developer and an input port for unused developer (toner mixed). A mouth 92 is formed. The agent exchange port 92 is covered from the outside by a cap 93 attached with a screw 94. (Hereafter, margin)

Here, in the rotary developing device 4, since the developing device unit 40 is repeatedly rotated, when the developing device unit 40 is located at a rotation position where the developer is above the developing roller 84. That is, when the developing roller 84C and the developing roller 84M in FIG. 3 are positioned, the developer tends to move downward in the developing device due to the influence of gravity. Since this developer has a certain degree of fluidity, it tends to move laterally toward the end portions in the longitudinal direction of the developing rollers 84C and 84M. Here, a magnet 201 as a magnetic field generating means is usually provided at the end portion in the longitudinal direction.
Since the magnetic force of the magnet 201 does not exist, if the developer moves laterally to the end portion in the longitudinal direction, the magnet 201 can no longer control the developer by the magnetic force. I will end up. For this reason, when the developing device unit 40 is rotated to set the developing roller 84C in FIG. The developer as it is remains in the developing roller 8 accompanying the developing operation.
It is conveyed to the developing port at once by the rotation of 4C. When the developer conveyed to the developing port at one time returns to the inside of the developing device with the rotation of the developing roller 84C, the developer returns from between the developing device casing 83 forming the developing port and the developing roller 84. The developer cannot be completely cut off, and the developer overflows from the developing port.

Therefore, in the present embodiment, when the developing roller is in the position such as the developing rollers 84C and 84M in FIG. 3, it is prevented that the developer gets around the end portion of the developing roller, and the developer overflows as described above. The structure is adopted so as not to cause. Hereinafter, the configuration for preventing the agent from entering the end portion of the developing roller 84 will be described with reference to FIG. FIG. 4 is a diagram of the black developing device of FIG. 3 viewed from the photosensitive drum 1 side. In the illustrated example, the roller shaft 84a of the developing roller 84 having the magnet 201 as the magnetic field generating means inside is provided with the end wall 5 as the developing roller support.
It is supported from both sides at 0,51. Then, the mylar 210 that covers the outer peripheral edge of the developing roller facing the agitator side.
a, a first regulating member 210b that covers the outer peripheral portion from the agitating portion to the doctor blade 85, and a second regulating member 210c that covers after the doctor has passed and up to the developing port. , 51 to the central portion of the developing roller 84 in the longitudinal direction, respectively.
01 end portion is formed so as to project with a predetermined width C. As shown in FIG. 5, the magnet 201 in the developing roller 84 is
Is provided so as to cover the outer peripheral portion of the developing roller 84 which is not exposed from the developing port of the developing device with gaps A and B between the developing roller 84 and the magnetic brush formed by the magnetic force. It should be noted that the predetermined width C in the present embodiment is, in the longitudinal direction of the developing roller 84,
The length is set to about 3 mm from the end of the magnet 201 in the longitudinal direction.

In this structure, the ends of the developing roller 84 protruding from both sides of the developing roller both end walls 50 and 51 supporting the developing roller 84 on the longitudinal end side to the central portion side in the longitudinal direction of the developing roller 84 with a predetermined width C. Since the outer peripheral portion of the developing roller 84 which is not exposed from the developing port of the developing device is covered by the partial covering member 210 so as to come into contact with the magnetic brush formed on the developing roller 84 by the magnetic force of the magnet 201,
The gap between the developing roller 84 and the end portion covering member 210 is closed by a magnetic brush of developer formed by the magnetic force of the magnet 201. Therefore, unlike the case where the end portion covering member 210 is not provided, when the developing roller 84 is located at a rotation position where the developer is present above the developing roller 84 due to the rotation of the developing device unit 40, a certain amount of flow occurs. The developer having a property moves downward in the developing device due to its own weight, and further, on the developing roller 84 in a direction orthogonal to the developer conveying direction, that is, the developer is at both end sides in the longitudinal direction of the developing roller 84. Even if the developer is moved to, the developer does not go around to the end portion of the developing roller 84 through the gap.

According to the above embodiment, the gap between the developing roller 84 and the end portion covering member 210 is closed by the magnetic brush of the developer formed by the magnetic force of the magnet 201, so that the end portion of the developing roller 84 is developed. Since it is possible to prevent the agent from wrapping around, it is possible to prevent the agent from overflowing when the developer does not have the end portion covering member 210 and the developer wraps around the end portion.

The gap between the mylar 210a and the surface of the developing roller 84 is preferably such that the developer is not fixed or aggregated. For example, in the present embodiment, when the gap is set to be narrower than 1 mm, the developer is rubbed at a high pressure in the gap, whereby the developer is aggregated, and the aggregated developer causes packing in the gap. . Further, the packed developer and the developing roller 84
As the frictional force between the developer increases, the developer melts,
The occurrence of sticking of the developer, which is caused by the melted developer sticking to the developing roller 84 side, becomes remarkable.
In the case of 5, the developer, that is, the development lock occurs. On the other hand, if the width is set to be wider than 3 mm, the ears of the magnetic brush formed by the magnet 201 will be covered by the end cover member 21.
Since the magnetic field may not reach 0, it may not be possible to reliably magnetically seal the gap, so that the developer may get around the end portion of the developing roller 84 when the developing device unit rotates.

Therefore, in the present embodiment, at least the gap between the mylar 210a and a part of the developing roller 84 is 1 mm.
To 3 mm, the developer is not aggregated in the gap and the gap is closed by a magnetic brush, the developer is aggregated in the gap and the developer is fixed to the developing roller 84 side. Alternatively, the developing roller 84
It surely prevents the developer from getting around the edges.

In the example of FIG. 5, the gap between the mylar 210a and the developing roller 84 is A, the gap between the developing roller 84 and the first regulating member 210b covering the outer peripheral portion from the agitator to the doctor blade 85, and the doctor passage. The gap between the second regulating member 210c covering the rear and the developing port and the developing roller 84 is set to B, and the end cover member 210 is used to cover the magnet 20.
When the predetermined width that covers the end portion of 1 is C (see FIG. 4),
These values are set as in setting example 2 in the table below. (Hereafter, margin)

[Table 1] When the respective values of A, B, and C are set as in Setting Example 1 of Table 1, developer overflow can be prevented, but developer agglomeration occurs in the gaps A and B. Overflow and aggregation of the developer could be prevented.

The developing roller of the second regulating member 210c on the downstream side of the doctor blade 85 for regulating the magnetic brush made of the developer conveyed on the developing roller 84 to a predetermined height or amount in the developer conveying direction. The width in the longitudinal direction of 84 is the first regulating member 21 before passing the doctor blade 85.
If the width of the doctor blade 8 is the same as the width of 0b, or if the width of the width of 0b is made to project toward the central portion of the developing roller 84 in the longitudinal direction, the doctor blade 8
5 The developer after passing 5 swells at the end portion of the developing roller 84. Therefore, in order to prevent such swelling of the developer, the protrusion width after passing the doctor blade 85 is
It is desirable to set it so that it is narrower than the protruding width before passing the doctor blade 85.

Further, before starting the development, a control means may be provided for controlling the developing roller 84 housed in the developing device to rotate in a direction opposite to the rotating direction at the time of developing. By performing such control, the magnetic brush made of the developer carried on the developing roller 84 is regulated to a predetermined height or amount in the vicinity of the upstream side of the developing roller 84 in the developer carrying direction. One regulating member 2
The developer staying in the gap between 10b and the developing roller 84 is
When the developing roller 84 is rotated in the reverse direction, it is returned to the developer stirring section side of the developing device by the carrying magnetic force of the magnet 201.
Compared with the case where the developing roller 84 is not rotated in the reverse direction to the rotating direction at the time of developing before starting the development, the first regulating member 210b and the developing roller 84 in the vicinity of the upstream side of the doctor blade 85 in the developer conveying direction. The degree of agglomeration of the developer staying in the gap is relaxed. Therefore, unlike the case where the developer is not rotated in the reverse direction, the degree of aggregation of the developer on the developing roller 84 does not increase, so that the developer sticking to the developing roller 84 side in the gap can be prevented. It is possible to prevent development lock due to the developer sticking.

At the end of the developing roller 84 as shown in FIG. 6A or at the end of the magnet 201 disposed inside the developing roller 84 as shown in FIG. 6B,
A magnetic plate 240 as a magnetic member may be provided. Here, at the end portion of the developing roller 84 as shown in FIG. 6C, the magnetic force at the end portion is usually higher than the magnetic force at the central portion as shown in FIG. 7C. The magnetic plate 2
As shown in FIGS. 7A and 7B, 40 reduces the magnetic force at the end of the magnet 201, and the developing roller 84
It is possible to reduce the amount of the developer attracted by the magnetic force to the end portion side of. According to this, the end of the magnet 201,
Alternatively, as compared with the case where no magnetic member is provided at the end of the developing roller 84, that is, the case shown in FIG. 6C,
It is possible to reduce the amount of the developer attracted by the magnetic force on the end side of the magnet 201, and to reduce the amount of the developer getting around the end of the developing roller 84.

In the above-described embodiment, for example, as shown in FIGS. 8 (a) and 8 (b), in the case where the side seals 250 as the developer scattering preventing members are provided at both ends of the developing port. When the agent overflow occurs, the side seal 250 may be damaged due to the pressure of the overflowed developer, and the development lock may occur. However, since the edge covering member 210 is provided, the agent overflow can be prevented. It is also possible to prevent development lock that occurs due to breakage of the side seal 250.

[0041]

According to the invention of claims 1 to 5, the gap between the developer carrier and the end covering member is closed by a magnetic brush of the developer formed by the magnetic force of the magnetic field generating means. Since it is possible to prevent the developer from getting around to the edge of the developer carrier, it is possible to prevent the developer from overflowing when the developer does not have the edge covering member, which is caused by the developer getting around to the edge. There is an effect. Therefore, for example, when the side seals as the developer scattering prevention members are provided at both ends of the developing port, the side seals can be prevented from being damaged by the developer due to the overflow of the agent, and the side seals can be prevented. It is also possible to prevent the development lock caused by the damage.

In particular, according to the second aspect of the invention, packing of the developer can be prevented in the gap between the end covering member and the developer carrying member, and friction between the developer and the end covering member can be prevented. As a result, it is possible to prevent the developer from being fixed to the developer carrying member side due to frictional heat. Therefore, the development lock phenomenon caused by the developer in the gap which may occur due to the arrangement of the end portion covering member and the development It is possible to prevent the development lock phenomenon caused by the sticking of the agent. Further, since the packing of the developer is prevented, the end covering member does not receive an excessive force from the developer, so that the end covering member can be prevented from being damaged.

In particular, according to the third aspect of the invention, even if the developer after passing through the developer regulating member tries to move to the end portion side of the developer carrying member by the repeated rotation of the rotary developing device, the development is carried out. Since the escape path of the developer in the longitudinal direction of the agent carrier can be ensured, when the projecting width of the end covering member is the same on the upstream side and the downstream side in the developer transport direction with respect to the developer regulating member. As compared with the above, it is possible to prevent the swelling of the developer from occurring easily. Therefore, for example, when the side seal is provided, it is possible to prevent the side seal from being damaged by the developer rising at the end.

In particular, according to the invention of claim 4, compared with the case where the developer carrying member is not reversely rotated with respect to the rotation direction at the time of development, before the development is started, the development is carried out by the developer regulating member. Since the degree of cohesion of the developer retained in the gap between the end covering member and the developer carrier in the vicinity of the upstream side in the developer carrying direction is reduced, the degree of cohesion of the developer on the developer carrier is increased. In contrast to the above case, it is possible to prevent the developer from sticking to the developer carrier side in the gap and prevent the development lock due to the developer sticking.

In particular, according to the invention of claim 5, as compared with the case where no magnetic member is provided at the end of the magnetic field generating means or at the end of the developer carrying member, the end side of the magnetic field generating means. It is possible to reduce the amount of the developer attracted by the magnetic force of, and to reduce the amount of the developer coming around the end portion of the developer carrier.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a copying machine according to the present embodiment.

FIG. 2 is an exploded perspective view of a rotary developing device of the copying machine.

FIG. 3 is a sectional view of a developing unit of the rotary developing device.

FIG. 4 is a side view of the black developing device as seen from the photosensitive drum side.

FIG. 5 is a sectional view of a black developing device according to a modification.

FIG. 6A is an explanatory view showing a state in which a magnetic plate is provided at an end portion of a developing roller. (B) is an explanatory view showing a state in which a magnetic plate is provided at the end of the magnet. FIG. 6C is an explanatory view showing an end portion of the developing roller without a magnetic plate.

7A to 7C are explanatory views showing magnetic force distributions in the longitudinal direction of the respective developing rollers in FIGS. 6A to 6C.

FIG. 8A is an explanatory diagram showing a developing device in which side seals for preventing developer scattering are provided in regions opposite to the photosensitive drums at both ends of the developing roller. FIG. 8B is a side sectional view of the developing device of FIG. 8A viewed from the photosensitive drum side.

[Explanation of symbols]

1 photoconductor drum 4 Rotating developing device 40 developer unit 41 Black toner container 50 Front end wall 51 rear end wall 84 developing roller 84a Developing roller shaft 85 Doctor blade 201 magnet 210 Edge coating member 210a mylar 210b First regulating member 210c Second regulating member 240 magnetic plate 250 side seal

─────────────────────────────────────────────────── ─── Continuation of the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03G 15/01-15/01 117 G03G 15/08-15/095

Claims (5)

(57) [Claims] 1. A developing device unit having a plurality of developing devices arranged around a rotation axis is rotated about the rotation axis, and an arbitrary development device is loaded with a developer contained in the development device. The developing port where the body is exposed is moved to a developing position facing the latent image carrier, and is developed by the developer conveyed on the developer carrier by the magnetic force of the magnetic field generating means provided inside the developer carrier. In the rotary developing device for carrying out the above, a developer carrying member for supporting the developer carrying member on the longitudinal end side so as to cover the outer peripheral portion of the developer carrying member not exposed from the developing port of the developing device. An end coating member configured to project from at least one of the supports to the central portion side in the longitudinal direction of the developer carrier with a predetermined width is formed on the developer carrier by the magnetic force of the magnetic field generating means. Arranged so that it contacts the brush A rotary developing device characterized in that 2. The rotary developing device according to claim 1, wherein the gap between the end covering member and the developer carrying member is set to be larger than the developing gap between the developer carrying member and the latent image carrying member. And a rotary developing device. 3. The rotary developing device according to claim 1, wherein the protrusion width of the end portion covering member toward the central portion side in the longitudinal direction of the developer carrier is the developer conveyed on the developer carrier. The rotary developing device is characterized in that the downstream side is smaller than the upstream side in the developer conveying direction with respect to the developer regulating member that regulates the magnetic brush composed of the above to a predetermined height or amount. 4. A magnetic brush comprising a developer carried on the developer carrier before the development is started in the rotary developing device according to claim 1, wherein the developer carrier is rotatable in the forward and reverse directions. The developer retained in the gap between the end portion covering member and the developer carrying member in the vicinity of the upstream side in the developer transport direction with respect to the developer regulating member that regulates the developer to a predetermined height or amount is A rotary developing device comprising a control means for controlling the developer carrier to rotate in a direction opposite to a rotation direction during development so that the developer carrier is transported in a direction opposite to the developer transport direction. 5. The rotary developing device according to claim 1, wherein a magnetic member is provided at an end of the magnetic field generating means disposed inside the developer carrier or at an end of the developer carrier. And a rotary developing device.