JPH09179404A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heighten the effect of preventing the scatter of a developer in a developing area and prevent a visible image from being disarranged by providing a sealing member for preventing the scatter of the developer, and bringing the tip part of the sealing member into contact with the surface of a latent image carrier more on the rotating direction upper reaches side than the developing area, over the whole longitudinal length. SOLUTION: Sealing members 93, 93R, 93B for preventing the scatter of a developer existing in a developing area D are respectively provided at developing apparatus 3, 3R, 3B, and the tip part of the sealing member 93 of the developing apparatus 3 in a developing position is brought into contact with the surface of a photoconductor drum 11 more on the upper reaches side in the rotating direction of the photoconductor drum 11 than the developing area D. Accordingly, when the developing apparatus 3 is in developing action, that is, when the developer is most liable to scatter from the developing area D, the tip part of the sealing member 93 additionally provided at the developing apparatus 3 is in contact with the surface of the photoconductor drum 11 over the whole longitudinal length, so that the scatter of the developer can be effectively suppressed. Also since the tip of the sealing member 93 comes in contact with the upper reaches side in the rotating direction of the photocnductor drum 11, there is no fear of disarranging a visible image.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a developing device provided with a developer carrying member carrying and carrying a powdery developer, and a latent image carrier rotatably driven. The present invention relates to an image forming apparatus that visualizes an electrostatic latent image formed on a latent image carrier by the developer transported by a transport member to a developing area between the developer transport member and the latent image carrier. It is a thing.

[0002]

2. Description of the Related Art In an image forming apparatus of the above type configured as a copying machine or a printer, a powdery developer is conveyed to a developing area by a developer conveying member of the developing device to form an electrostatic latent image. It makes a visible image, but at the time of this operation,
A small amount of the developer existing in the developing area may be scattered. If left unattended, the scattered developer may adhere to various elements in the image forming apparatus, particularly optical elements, to deteriorate the function of the image forming apparatus or to contaminate the periphery of the apparatus.

In order to prevent such a problem, an image forming apparatus has been proposed which is provided with a seal member for preventing the scattering of the developer existing in the developing area. However, depending on the conventional seal member, the scattering of the developer can be prevented. It is difficult to enhance the effect, and the sealing member may disturb the visible image formed on the latent image carrier.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus of the type described at the outset, which eliminates the above-mentioned conventional disadvantages.

[0005]

In order to achieve the above object, the present invention provides an image forming apparatus of the type described at the beginning with a seal member for preventing the scattering of the developer existing in the developing area. An image forming apparatus is proposed in which the tip portion of the above is brought into contact with the surface portion of the latent image carrier on the upstream side in the rotational direction of the latent image carrier with respect to the entire length in the longitudinal direction thereof.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a sectional view showing a main part of an image forming apparatus configured as a copying machine. A photosensitive drum 11 which is an example of the configuration of a latent image carrier rotatably driven, and developing devices 3 and 3.
It has R and 3B. A latent image carrier composed of a photosensitive belt may be used instead of the photosensitive drum, and a latent image carrier composed of a dielectric belt or a dielectric drum may be used depending on the model of the image forming apparatus. Also, in this example,
A plurality of developing devices 3, 3R, 3B are integrally assembled, and this is configured as one developing unit 1. The developing unit 1 is supported by the image forming apparatus main body (the copying machine main body 2 in this example) so as to be able to be pulled out, and FIG. 2 shows a state where the developing unit 1 is pulled out from the copying machine main body 2. There is. The developer chambers 4, 4R, 4B of the developing units 3, 3R, 3B incorporated in the developing unit 1 are
It is partitioned by three partition walls 6, 6R, 6B of the casing member 5 made of a non-magnetic material such as aluminum and two end walls 7, 8 (Fig. 2) fixed to both ends thereof.

In the developer chambers 4, 4R, 4B of the developing units, powdery developers 9, 9R, 9B of different colors are contained, and in the present example, these developers are black. , Red, and blue. In each developer chamber, a developer of cyan, yellow and magenta toners is stored,
It can be configured to form a full-color image. Although a one-component developer containing no carrier can be used as the developer, in the example shown in the figure, a two-component developer having a carrier and a toner, at least a part of which is a magnetic developer Shall be used.

Although the first to third developing units 3, 3R and 3B are arranged radially around the central axis O of the developing unit 1, since their structures are all the same, they will be described below. The structure of the first developing device 3 is mainly clarified, and R and B are attached to the reference numerals assigned to the respective elements of the first developing device 3 for the respective portions of the other developing devices 3R and 3B.

As will be described later, the developing unit 1 is rotatably supported around its central axis O, and each developing device rotates to a predetermined developing position to perform a developing operation. The state where the container 3 occupies the developing position is shown.

In FIG. 1, the developing device 3 has a developer carrying member for carrying and carrying a powdery developer, in the example of the drawing, a developing roller 10, and the developing roller 10 has two partition walls 6. , 6R partially exposes through the opening (Fig. 2
See also), and occupies a predetermined position with respect to the photosensitive drum 11 rotatably supported by the copying machine main body 2. In this example, the developing roller 10 is positioned parallel to the photosensitive drum 11 with a predetermined minute gap.

Inside the developing roller 10, S and N shown in FIG.
A magnet 21 having a magnetic pole composed of an S pole and an N pole is fixedly arranged in the casing member 5 of the developing unit 1 as indicated by the symbol. Thereby, when the developing roller 10 of the developing device 3 brought to the developing position facing the photosensitive drum 11 is rotationally driven in the counterclockwise direction in FIG. 1, the developing roller 10 has the blade 15 and rotates in the counterclockwise direction. The magnetic developer 9 supplied to the developing roller 10 while being stirred and charged by the impeller 16 is
The developer is carried on the surface of the developing roller 10 by the magnetic force of the magnet 21 and is conveyed counterclockwise. The conveyed developer is scraped by a doctor blade 22 fixed to the casing member 5, and a predetermined amount of the developer passing through the blade 22 is sent to the photosensitive drum 11 with its layer thickness regulated.

On the other hand, the photosensitive drum 11 is rotationally driven in the clockwise direction in FIG. 1, and an electrostatic latent image corresponding to an original (not shown) image is formed on the surface thereof by charging / exposure means (not shown). It is formed in a manner known per se. When this latent image reaches the opposing development area D between the photoconductor drum 11 and the developing roller 10, the charged toner in the developer also conveyed to this area D is electrostatically transferred to the electrostatic latent image, and the latent image is formed. Is visualized.

As described above, the image forming apparatus according to the present embodiment includes the developing device 3 including the developer conveying member including the developing roller 10 that carries and conveys the powdery developer, and the photosensitive member that is rotationally driven. A latent image carrier configured as the body drum 11, and by the developer carrying member, the developer conveyed to the developing area between the developer carrying member and the latent image carrier,
It is configured to visualize the electrostatic latent image formed on the latent image carrier. In the illustrated example, the developing device occupying the developing position executes the developing operation.

The visible image formed on the photosensitive drum 11 as described above is transferred onto a transfer paper (not shown) by a transfer device (not shown), and the transferred visible image is fixed by a fixing device (see FIG. It is fixed by (not shown). The developer that has passed through the development area D is returned to the inside of the developer chamber 4 again, mixed with another developer in this chamber, and used again.

Since the toner in each developer chamber is sequentially consumed with the progress of the above-described developing operation, each of the developer chambers 4, 44 R and 44 B shown in FIG.
The toner is supplied to 4R and 4B. In FIG. 1, only the position of the toner supply device is indicated by a chain line. Further, the developing unit 1 in this embodiment is carried on a unit carrier as described below.

That is, as shown in FIGS. 1 to 3, the slider 6
2 is pulled out to the front side (direction of arrow G in FIG. 2) of the main body 2 of the copying machine by a slide guide device 61 known per se or, conversely, is pushed toward the back side (also direction of arrow H). It is slidably supported by the main body 2,
The developing unit housing 63 is supported by the slider 62. The slider 62 and the unit storage 63 constitute a unit carrier.

The slider 62 has a support plate 64 on the front side, a support plate 65 on the back side, and a substrate 66 connecting these,
The support plates 64, 65 have first to third connecting rods 67, 68, which extend parallel to each other in the sliding direction of the slider 62.
Each end of 69 is fixed, and these connecting rods 6
Both support plates 64, 65 are reinforced by 7, 68, 69.

The storage base 63 also has a front side support arm 70 and a rear side support arm 71, and these arms 70, 71 are provided.
A lower cover 72 is fixed to the. Also storage 63
An upper cover 75 is rotatably supported by a pivot pin 73 in the direction of arrow J, and the upper cover 75 is normally held in the closed position shown in FIG. 1 (the position indicated by the chain line in FIG. 2). There is.

On the other hand, the outer peripheral surface of the end wall 7 on the front side of the developing unit 1 is formed in a cylindrical shape, and the outer peripheral surface of the end wall 8 on the rear side is also cylindrical. Both support arms 7 of storage table 63
The upper portions 70a, 71a of the base plates 0, 71 are formed in an arc shape adapted to the outer peripheral surfaces of the end walls 7, 8, and two support rollers 76, 77 are rotatably supported by the support arm 70 on the near side. , The outer peripheral surface of the end wall 7 on the front side of the developing unit 1
These support rollers 76 and 77 support the rollers at two places. When the slider 62 is pulled out of the copying machine main body 2, the cylindrical end wall 8 on the back side of the developing unit 1 is rotatably supported on the arc-shaped upper portion 71a of the support arm 71 on the back side. , The developing unit 1 is a storage table 6
3 while being supported by it, it can rotate about its central axis O.

When the developing unit 1 is set, the slider 62 is held while the developing unit 1 is carried on the storage table 63.
Only in the direction of arrow H (FIG. 2), and when this pushing operation is completed, the rear end wall 8 of the developing unit 1
A positioning pin 78 protruding from the center axis O of the unit 1 is rotated by a positioning hole (also not shown) formed in a rear side plate (not shown) of the copying machine main body 2. The developing unit 1 is positioned freely with respect to the copying machine main body 2, that is, the photosensitive drum 11 supported at a predetermined position of the main body 2. The end wall 7 on the front side remains rotatably supported by the two support rollers 76 and 77 even after the setting of the developing unit 1, but the pin 82 protruding from the support arm 70 on the front side of the storage table 63.
Is fitted into a positioning hole formed in the front side plate 83 of the copying machine main body 2 or a center hole of the receiving member 85 fitted therein, and the front side of the storage base 63 is positioned with respect to the photosensitive drum 11. Is done.

On the other hand, as also schematically shown in FIG. 4, a unit drive motor 88 is supported by the storage base 63, and this motor 88 is provided in the developing unit 1 via a gear 89 supported by the storage base 63. It is drivingly connected to the unit gear 90. When a visible image is formed by the second or third developing device 3R, 3B, the unit 1 is rotationally driven by the motor 88 around the rotation center O, and each developing device 3R, 3B is rotated.
3B is brought to the developing position where the first developing device 3 shown in FIGS. 1 and 4 is located, and the developing operation is performed. In this way, the unit drive motor 88 is used for the plurality of developing devices 3, 3R, 3B.
The developing unit 1 is rotatably driven so that the selected one of the developing units occupies the developing position facing the photosensitive drum 11.

When the developing operation described above is performed by the developing device brought to the developing position, the developing roller 1
The developer existing in the developing area D transported by 0 scatters to some extent, and if left undisturbed, the developer scatters in all directions as described above, which causes various elements inside the copying machine body, especially optical elements. Adheres to and reduces the function of the copier,
Alternatively, the area around the copying machine may become dirty.

Therefore, in the image forming apparatus of this example,
Sealing members 93, 93R, 93B for preventing the scattering of the developer existing in the developing area D are provided in the developing units 3, 3R, 3B, respectively, and the respective seal members have a base end side of the developing unit main body, that is, It is fixedly fixed to the casing member 5 of the developing unit 1. The seal member is made of, for example, an elastic film made of synthetic resin, a sheet (polyester film, polyurethane rubber sheet, etc.), a flexible brush, or the like. As shown in FIG. When the operation is executed, the tip end portion of the seal member 93 attached to the developing device 3 extends over the entire length in the longitudinal direction, and the rotation direction of the latent image carrier formed of the photoconductor drum 11 is larger than the developing area D. It is in contact with the surface of the latent image carrier on the upstream side. That is, the tip of the seal member 93 of the developing device 3 at the developing position abuts on the surface of the photosensitive drum on the upstream side in the rotation direction of the photosensitive drum with respect to the developing area D, and the developer is more photosensitive than the seal member 93. It is prevented from scattering to the upstream side in the drum rotation direction. The seal members 93R and 93B of the other developing devices 3R and 3B also have the same seal members 93R and 93B as the seal members 93 shown in FIG. 1 when the developing devices 3R and 3B are brought to the developing position. The developer is prevented from scattering by contacting the surface of the photosensitive drum 11 in exactly the same manner.

As described above, in the image forming apparatus of this example, when the developing device is performing the developing operation, that is, when the developer is most likely to be scattered from the developing area D, the developing device is attached to the developing device. The leading end of the sealing member, that is, the free end side thereof, extends over the entire length in the longitudinal direction of the photosensitive drum 11.
Since it comes into contact with the surface of the developer, scattering of the developer can be effectively suppressed. If the tip of the seal member is slightly separated from the surface of the photosensitive drum, or if only a part of the seal member in the longitudinal direction is in contact with the surface of the photosensitive drum, the seal member is In spite of the provision, the problem that the developer in the developing area D is scattered to the upstream side in the rotation direction of the photosensitive drum cannot be avoided. According to the seal member of this example, it is possible to prevent such a problem from occurring. Further, the seal member of this example has its tip end abutted on the surface of the photoconductor drum 11, but since it abuts on the photoconductor drum surface portion on the upstream side in the rotation direction of the photoconductor drum than the developing region D, There is no fear that the seal member disturbs the visible image on the photosensitive drum.

By the way, in order to select the developing device to be used, the developing unit 1 is connected to the unit driving motor 8 as described above.
8, the seal members 93, 93R,
93B also rotates together with the unit 1, so that the developing device that has occupied the developing position or the seal member of the developing device that moves to the developing position is in sliding contact with the peripheral surface of the photosensitive drum 11, and is exposed to external force from the photosensitive drum 11. Bending deformation. At this time, assuming that the developing unit 1 rotates around its center O in the counterclockwise direction in FIG. 1, the sealing member 93 is moved from the photosensitive drum 11 so that the front end thereof is pressed against the mounting posture. Under an external force, the sheet is largely bent and deformed as shown in FIG. Therefore, in some cases, the seal member 93 may be damaged, or conversely, the seal member may damage the surface of the photosensitive drum 11.

Therefore, in the illustrated image forming apparatus, all the seal members 9 are rotated when the developing unit 1 is rotated.
The rotation direction of the developing unit 1 is set so that the base ends of 3, 93R, 93B always move downstream from the free ends. In the example of FIG. 1, the developing unit 1 is configured to always rotate only clockwise in FIG. With this configuration, when the developing unit 1 rotates, the seal member 93 only needs to be slightly bent and deformed due to the mounting posture thereof, and a large external force is exerted on the seal member 93 and the photosensitive drum 11. Can be removed. That is, the developing unit 1 is rotated only in a direction in which the amount of bending deformation of the seal member by the external force received from the photosensitive drum 11 during rotation of the developing unit is reduced, and each developing unit is brought to the developing position. The same applies to the sealing members 93R and 93B attached to the other developing units 3R and 3B, and the deformation amount is kept small.

Incidentally, reference numeral 94 in FIG. 1 is a second seal member provided on the upper cover 75.
Reference numeral 4 also contacts the photosensitive drum 11 and forms a double seal together with the seal member 93 described above.

In the image forming apparatus illustrated as described above, the developing unit 1 is rotated and driven around the center thereof in the same direction, in the present example, in the clockwise direction (direction of arrow Q) in FIGS. 1 and 4. However, even when a force to rotate the developing unit 1 in the counterclockwise direction opposite to the clockwise direction acts on the developing unit 1 when the developing unit 1 is stopped, the developing unit 1 is driven. The gear 89 and the unit drive motor 88 positively prevent the developing unit 1 from rotating counterclockwise. This has the following advantages.

That is, the developing roller 10 of the developing device 3 occupying the developing position as shown in FIGS. 1 and 4 rotates counterclockwise in these figures during the developing operation, but its load is the developer. It becomes very large due to the circulation of.
Moreover, since the developing roller 10 occupies a position largely deviated from the rotation center O of the developing unit 1, the developing roller 10
By the counterclockwise rotation (rotation) of the developing unit 1,
, A large counterclockwise moment acts on the rotation center O thereof. Therefore, the developing unit 1 is shown in FIG.
And try to rotate counterclockwise in FIG. 4 (opposite to Q). At this time, if the developing unit 1 actually rotates, the developing roller 10 will be displaced from the predetermined position,
It becomes impossible to perform a predetermined developing operation. However, as described above, when the developing unit 1 is stopped, the rotation in the counterclockwise direction is positively prevented by the gear 89 or the unit drive motor 88 or the like, so that the developing roller 10 does not move from a predetermined position. Therefore, there is no adverse effect on the developing operation. It is also advantageous to provide locking means so that the developing unit 1 does not rotate counterclockwise.

Further, if the developing unit 1 is rotationally driven only in a fixed direction, the following advantages can be obtained.

As shown in FIG. 4, developing roller gears 14, 14R, 14B are fixed to the developing rollers 10, 10R, 10B rotatably supported by the developing unit 1 (see FIG. 3).
(See also), the developing roller gear of the developing roller brought to the developing position by the rotation of the developing unit 1 is in a suitable place other than the developing unit 1, for example, the drive gear 111 rotatably supported by the support shaft of the photosensitive drum 11. Mesh with each other. FIG. 4 shows the first
4 shows a state in which the gear 14 of the developing roller 10 meshes with the driving gear 111. During the developing operation, the driving gear 111 rotates clockwise (direction of arrow R) in FIG. Driven clockwise.

When changing the developing device to be used, the developing unit 1 is rotated by the unit driving motor 88, and at this time, the developing roller gears 14, 14R and 14B are set in the unit 1.
The developing roller gear of the developing device selected by revolving the rotation center O of the above meshes with the drive gear 111. In this case, by rotating the developing unit 1, one of the developing roller gears 14,
When 14R and 14B start to engage with the drive gear 111,
As shown in FIG. 6, the tooth tip of the developing roller gear and the drive gear 11
The tooth tips of one may abut each other. If such a situation occurs, there is a risk that these gears will stop or the gear teeth will be cut off.

To eliminate this inconvenience, the drive gear 11
By the time immediately before starting to mesh with the driving gear 111,
May be configured to have already started rotating clockwise (direction of arrow R) in FIG. That is, when the developing roller gear revolves and any of the gears engages with the drive gear 111, the gear 111 is already rotated. With this configuration, when the developing roller gear, for example, the gear 14 of the first developing device 3 starts to mesh with the driving gear 111, it is assumed that the tooth tips of the two gears 14 and 111 abut as shown in FIG. Also, by the rotation of the drive gear 111, both gears immediately release the abutment between the tooth tips,
A predetermined correct meshing state results.

Since the rotation of the drive gear 111 may start immediately before any of the developing roller gears starts to engage with the gear 111, the drive gear 111 is rotated at the same time when the developing unit 1 starts to rotate. The process may be started, or the drive gear 111 may be continuously rotated when the power of the copying machine is in the on state. In this case, the higher the relative speed between the drive gear 111 and the developing roller gear that is to be engaged with the drive gear 111 in the engagement area, the more quickly the abutment between the tooth tips of the two gears can be released. In this example, the rotation direction of the driving gear 111 must be clockwise because the developing roller gear needs to be rotated in the counterclockwise direction. Therefore, the relative speed between the driving gear 111 and the developing roller gear to be engaged with the driving gear 111 is required. In order to achieve this, the developing roller should be revolved clockwise in FIG. 4 (direction of arrow Q). To achieve this, the rotation direction of the developing unit 1 must be clockwise in FIG. Q
Direction), which coincides with the rotation direction of the developing unit 1 described above. In other words, by rotating the developing unit 1 only in this direction, it is possible to prevent the abutment between the tooth tips at the start of the engagement between the developing roller gear and the driving gear 111, or to immediately release the abutment. .

As shown in FIG. 5, when the driving gear 111 is arranged inside the developing roller gear 14 of the developing device at the developing position and the developing roller gear is rotated counterclockwise during the normal developing operation, Since the rotation direction of the drive gear 111 is clockwise, in this case, the developing unit 1
Is rotated counterclockwise around its center O, and if each developing roller is revolved in this direction, this gear will become the driving gear 111 which has already started to rotate clockwise.
In addition, the two engagement areas are engaged with each other with a large relative speed, so that abutment between the tooth tips can be prevented. When the rotation direction of the developing unit 1 is set in the opposite direction to that in FIG. 1, the mounting posture of each of the seal members 93, 93R, and 93B is changed so that they do not bend significantly when the developing unit rotates. do it.

According to the present invention, the developer carrying member is a member other than the developing roller, for example, the developing device composed of a carrying belt, or the developer carrying member does not rotate, but the magnet provided therein rotates, or both of them. The present invention can also be applied to an image forming apparatus having a developing device of a rotating type, a developing device using a non-magnetic developer, and the like, and also to an image forming apparatus such as a printer other than a copying machine.

[0038]

According to the image forming apparatus of the first aspect of the present invention, when the developing device is performing the developing operation, the tip portion of the seal member extends over the entire length in the longitudinal direction of the surface of the latent image carrier. It is possible to effectively prevent the scattering of the developer existing in the developing area. Moreover, since the seal member abuts on the surface portion of the latent image carrier on the upstream side in the rotation direction of the latent image carrier with respect to the developing area, the seal member disturbs the visible image on the latent image carrier. There is no fear.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a main part of an image forming apparatus.

FIG. 2 is a perspective view showing a state in which a developing unit is pulled out from a copying machine main body and the unit is removed from a storage table.

FIG. 3 is a perspective view of the copier main body as viewed from the rear side with the developing unit removed.

FIG. 4 is an explanatory diagram showing a rotating operation of a developing unit.

FIG. 5 is an explanatory diagram showing another arrangement of gears.

FIG. 6 is an explanatory diagram for explaining a collision between tooth tips.

FIG. 7 is an explanatory diagram showing a state in which a large external force is applied to a seal member in contact with the photosensitive drum and the seal member is greatly deformed.

[Explanation of symbols]

 3 developing device 3R developing device 3B developing device 9 developing agent 9R developing agent 9B developing agent 93 sealing member 93R sealing member 93B sealing member D developing area

Claims (1)

[Claims] 1. A developing device having a developer carrying member for carrying and carrying a powdery developer, and a latent image carrier rotatably driven. In an image forming apparatus that visualizes the electrostatic latent image formed on the latent image carrier by the developer conveyed to the developing region between the agent transport member and the latent image carrier, the development in the developing region is performed. A seal member for preventing the agent from scattering is provided, and the tip end portion of the seal member is in contact with the latent image carrier surface portion on the upstream side in the rotational direction of the latent image carrier with respect to the developing region over the entire length in the longitudinal direction. An image forming apparatus characterized by the above.