JPH0833687B2 - Image forming device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention generally relates to an image forming apparatus, and is particularly suitable for an image forming apparatus in which an electrophotographic recording system, an electrostatic recording system or the like is adopted in an image forming process. Applied.

As is well known in the prior art, a two-component developer composed of a toner and a carrier has a property of deteriorating when continuously used for a certain period. Therefore, in a developing device containing such a two-component developer, various means have been conventionally used as a method for regularly exchanging the two-component developer contained in the device. There is. For example, the proposal concerning the above-mentioned method is disclosed in Japanese Patent Publication No. 50-28263. The outline of the proposal disclosed in the publication is to open a partial section of the developer circulation path set in the developing device to remove a deteriorated two-component developer contained in the developing device. A carrying means such as a screw is carried out of the developing device and collected. In addition,
For details of the configuration described above, refer to the above-mentioned publication.

Problems to be Solved by the Invention By the way, in the developing device according to the above-mentioned proposal,
When the developing device is in a developing position facing the outer peripheral surface of the photosensitive drum, which is an image carrier in the image forming apparatus, the screw or the opening of the developing device described above is used to collect the deteriorated two-component developer. When only the developing sleeve arranged so as to face is driven, the two-component developer spills out from the gap defined by the developing sleeve and the photosensitive drum because the photosensitive drum is stopped. Each part in the image forming apparatus is contaminated by the spilled two-component developer, or only a specific position on the outer peripheral surface of the photosensitive drum is in sliding contact with the two-component developer. There was a problem such as adversely affecting the photoconductor drum. or,
If the two-component developer is collected while rotating the photoconductor drum, the above-mentioned problems can be eliminated, but the two-component developer adheres to the outer peripheral surface of the photoconductor drum. Electrical control such as bias voltage application must be performed, which complicates the operation sequence of the apparatus and causes a problem in safety during the developer collecting operation. Further, if only the screw is rotated without rotating the developing sleeve, there is a problem that the developer adhering to the outer peripheral surface of the developing sleeve cannot be collected.

Therefore, for the purpose of eliminating the above-mentioned problems and the occurrence of various problems, by rotating the magnet roller inside the developing sleeve rotatably arranged facing the opening of the developing device, A method has been proposed in which the repulsive magnetic pole of the magnet roller is moved to the developing position side and the developer is recovered by utilizing the repulsive magnetic field generated by the repulsive magnetic pole. The method according to the proposal, for example, the diameter 32
When a developing device having a 5 mm developing sleeve and a magnet roller having a 5-pole magnetic pole including the repelling magnetic pole disposed in the developing sleeve is adopted, the repelling magnetic pole in the developing sleeve becomes an obstacle and deteriorates the development. There was a problem that the recovery time of the agent was very long.

Furthermore, in such a developing device, the magnet roller, which is originally an important process element that is fixedly provided in the developing sleeve, is rotationally moved to recover the deteriorated developer. Because I have to let
Not only does electrical and mechanical means are required to rotate the magnet roller in the developing sleeve, but after recovering the deteriorated developer, each magnetic pole forming the magnet roller can be accurately returned to the home position. Electrical and mechanical means are also required. Therefore, there is a problem that the configuration of the developing device becomes extremely complicated.

Therefore, the present invention was devised in order to solve the above-mentioned problems, and an object thereof is to remove a deteriorated developer stored in a developing device without complicating the structure of the developing device. An image forming apparatus having a developing device capable of easily and surely collecting each portion of the image forming apparatus without being contaminated, and not damaging each portion inside the image forming apparatus including the outer peripheral surface of the photosensitive drum. Is to provide.

Means for Solving the Problems The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention is directed to a first
A developer carrying member which contains a magnet and carries a developer, a developing device which has the developer carrying member and faces the image carrying member at the developing position, and a developer collecting position which is remote from the developing position. And a developer collecting device for collecting the developer in the developing device into a collecting container, wherein the developing device can move between the developing position and the developer collecting position. The developer collecting device is stationary, and has a developer carrying body containing a rotating second magnet, and the developer carrying body in the developing device is rotatable in any direction when collecting the developer. And an image forming apparatus.

Embodiment Hereinafter, an embodiment according to the present invention will be described with reference to the drawings.

This embodiment shows a case where the present invention is applied to a full-color electrophotographic copying machine, which is an example of an image forming apparatus. However, in a multi-color electrophotographic copying machine, a color recording device connected to an output section of a computer, etc. Of course, the present invention can be easily applied to other image forming apparatuses equipped with a developing device that accommodates a two-component developer.

FIG. 1 shows an embodiment of an image forming apparatus for forming a full-color copy image embodying the present invention. In FIG. 1, an image carrier, that is, a photosensitive drum 1, is disposed in a region near the left of the center of the inside of the main body of the image forming apparatus. An exposure optical system 3 including a charger 2 is provided in an upper region near the outer peripheral surface of the photosensitive drum 1 in the main body of the image forming apparatus. In the main body of the image forming apparatus, the developing device 4 is arranged in the left region near the outer peripheral surface of the photoconductor drum 1, and the cleaning device 6 is arranged in the region facing the developing device 4 with the photoconductor drum 1 interposed therebetween. It is set up.
A transfer system 5 is arranged in a lower region near the outer peripheral surface of the photosensitive drum 1 in the main body of the image forming apparatus. In the area near the developing device 4 in the image forming apparatus main body, that is, in the lower left area in the image forming apparatus main body, a developer recovery container 12 and a motor M for driving each part of the image forming apparatus main body are arranged.
A fixing device 9 is disposed in an upper right area of the image forming apparatus main body, and one end side of the image forming apparatus main body is attached to the fixing device 9 so that the discharge tray 10 can be detachably attached. Is provided. At the lower right end of the main body of the image forming apparatus, a paper feed cassette 7 is detachably attached to the main body of the apparatus.

The photosensitive drum 1 is rotatably supported in the direction of arrow A in FIG. The charger 2 uniformly charges the outer peripheral surface of the photosensitive drum 1 at a predetermined potential. The exposure optical system 3 has a document scanning unit 3a and a color separation filter 3b.

The developing device 4 includes, for example, a yellow developing device 4Y containing a yellow developer, a magenta developing device 4M containing a magenta developer, a cyan developing device 4C containing a cyan developer, and a black developing device containing a black developer. It has four developing units of the container 4BK. In the present embodiment, the developing device 4 has a developing device supporting means, that is, a rotating body 100, which is attached concentrically to the central shaft 101 with respect to the central shaft 101 and rotates the surrounding of the central shaft 101, The four developing devices are attached to the rotating body 100.
A rotary developing device is used, in which 4Y to 4BK are detachably housed at angular intervals of approximately 90 °. However, the developing device 4Y
The developing device supporting means that holds and conveys 4BK is not necessarily a rotating body, and may be an endless moving body other than the rotating body. That is, the developing device may be configured so that each of the developing devices 4Y to 4BK can be moved along the non-circular orbit by the endless moving body.

The developing devices 4Y to 4BK are the same as those of the applicant's application.
As described in JP-A-5-20579, a developer carrying member having a permanent magnet (magnet roller), that is, a developing roller 46 is provided, and each developing device 4Y to 4BK rotates and moves together with the rotating member 100. However, the developer is prevented from scattering due to the action of the magnetic field from the permanent magnet. The developing roll 46 may itself be a multi-pole magnetic pole roll, or may be composed of such a magnet roll and a developing sleeve surrounding the magnet roll. As is clear from the above description, the developing device 4
By rotating the rotator 100 around the central axis 101 in the direction of arrow B in FIG. 1, the developing devices 4Y, 4M, 4C,
The 4BKs are respectively conveyed to the developing positions facing the outer peripheral surface of the photosensitive drum 1, and the developing process is performed.

The transfer system 5 includes a transfer drum 5b having a gripper 5a, and a transfer discharger 5c arranged on the inner peripheral side of the transfer drum 5b. A transfer material separating unit 8 is provided near the outer peripheral surface of the transfer drum 5b. The transfer drum 5b winds the transfer material supplied from the paper feed cassette 7 around the outer peripheral surface of the transfer drum 5b by the gripper 5a, and rotates in the arrow direction in FIG. When the transfer discharger 5c is driven, the visible image of each color formed on the outer peripheral surface of the photoconductor drum 1 is sequentially transferred to the transfer material wound and held on the outer peripheral surface of the transfer drum 5b. A full-color visible image is formed on the transfer material. Transfer material separating means 8
Is configured to separate the transfer material, which is wound and held on the outer peripheral surface of the transfer drum 5b and on which the full-color visible image is transferred, from the outer peripheral surface of the transfer drum 5b. The fixing device 9 receives the transfer material separated from the outer peripheral surface of the transfer drum 5b by the transfer material separating means 8, fixes the full-color visible image transferred onto the transfer material on the transfer material, and then discharges the paper. It is designed to discharge to tray 10.

FIG. 2 visualizes the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 1 when one of the developing devices constituting the developing device 4 shown in FIG. 1 is at the developing position. It shows the state of being. The developing position shown in FIG. 2 is
A developing device facing the outer peripheral surface of the photosensitive drum 1 in FIG.
This is the 4Y position. The developer collecting position shown in FIG. 8 is the position of the developing device 4M at the lowermost position inside the image forming apparatus main body shown in FIG. As is clear from the contents already described, the developer recovery container 12 is disposed near the lower part of the developing device 4M as a developer recovery device for recovering the deteriorated developer. Further, during the normal copying process, the necessary driving force is supplied only to the developing device at the developing position, that is, the developing device 4Y here.

Since the developing devices 4Y to 4BK described above have the same structure, the developing devices at the developing position are shown in FIG.
I will explain 4Y in detail.

As is apparent from FIG. 2, the developing device 4Y includes a developing container 41 and a developing container provided inside the developing container 41.
41 a partition plate 42 for partitioning the inside, and screws 43, 44 respectively arranged in the space section partitioned by the partition plate 42,
The developing roller 46 is provided at the opening of the developing container 41, and the doctor blade 45 is provided at the opening so as to face the outer peripheral surface of the developing roller 46. Second of partition plate 42
The front side of the drawing and the back side of FIG. 2 are voids so that the developer can be circulated. The screw 43 moves in the direction of the arrow in FIG. 2 (counterclockwise direction in FIG. 2), and the screw 44 moves in the direction of the second
They are arranged so as to be rotatable in the directions of arrows in the drawing (clockwise in FIG. 2). The screw 43 and the screw 44 are rotationally driven to cooperate with each other to circulate and move the developer in the developing container 41. In the present embodiment, the developing roll 46 includes a fixed magnet 46a magnetized as shown in the figure, and encloses the magnet 46a in the vicinity of the outer peripheral portion of the magnet 46a so as to be rotatable in the arrow C direction in FIG. And a developing sleeve 46b attached. The developing sleeve 46b is provided to convey the developer, and by the rotation of the developing sleeve 46b, the developer drawn up by the S ₂ pole is disposed near the N ₂ pole. The amount of conveyance is restricted by the doctor blade 45 which is present, and the conveyance is performed in the order of S ₃ pole → N ₁ pole → S ₁ pole → S ₂ pole. The N ₁ pole is the main developing pole, and the developer that is in a so-called spike state at the N ₁ pole visualizes the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 1. The developer on the outer peripheral surface of the developing sleeve 46 then drops onto the screw 43 in the developing container 41 due to the repulsive magnetic field generated from the S ₁ pole and the S ₂ pole.

As is well known, the rotary developing device 4 causes the developing devices 4Y to 4BK having the above-described configurations to sequentially rotate and move to the developing position, and the static developing device 4Y on the outer peripheral surface of the photosensitive drum 1 corresponding to the developer of each color. A full-color copy image is formed by sequentially converting the latent image into a visible image, but the developer deteriorates as the number of developed sheets increases. Therefore, it is necessary to collect the deteriorated developer in each of the developing devices 4Y to 4BK and periodically replace it with a new developer.

Therefore, in the rotary developing device 4 according to the present invention,
The developing device accommodating the deteriorated developer is rotationally moved to the above-mentioned developer collecting position, and at the same time, the driving force necessary for collecting the deteriorated developer is supplied only to the developing device, and other developing It was decided to control the drive of each developing device so that the developing device would not be driven. By performing such control, it is possible to reliably collect the developer carried on the outer peripheral surface of the developing roll 46 into the developer collecting container 12.

5 to 11 each show a state in which the developing device embodying the technical idea of the present invention collects the developer. That is, assuming that the developing unit existing at the developer collecting position shown in FIG. 8 is the developing unit 4M shown in FIG. 1, the developing unit 4M is the developing unit shown in FIG. This means that the developing device 4Y located at the position is present at a position rotated by 90 ° in the clockwise direction.

Next, the manner of collecting the developer according to the present invention will be described with reference to FIGS. In the developer recovery device shown in FIGS. 5 to 11, the developer recovery container 12 has a developer recovery sleeve 50 as a rotatable developer carrier having a substantially cylindrical shape at the opening thereof. ing. A magnet, that is, a second magnet 51 is rotatably provided inside the developer collecting sleeve 50. Where the sixth
FIG. 7 and FIG. 7 show the relative positional relationship between the developer recovery container 12 and each developing device when the developer is not recovered. Sixth
In the state shown in the figure, the magnetic pole N of the magnet 51 is
₃ is opposed to the magnetic pole N ₁ of the magnet roller 46 in the developing sleeve 46b. On the other hand, in the state shown in FIG.
Both the magnetic poles N ₃ and S _{4 of the} magnet 51 are located at positions separated from the position of the magnetic pole N ₁ of the magnet roller 46a.
That is, when the developer is not collected, the magnetic pole of the magnet 51 is
Since neither N ₃ nor S ₄ has any adverse effect on the developer on the outer peripheral surface of the developing sleeve 46b, the relative position of the magnet 51 may be set to either of FIG. 6 and FIG.

When the developer recovery container 12 recovers the deteriorated developer in each developing device, the magnetic pole S ₄ of the magnet 51 is used as a means such as a lever (not shown) provided at the end of the magnet 51. And rotationally move to a position facing the developing main pole N ₁ (see FIG. 5). Meanwhile, the developing sleeve 46
About b, it is driven by a developing sleeve drive motor driver 107 as shown in FIG. 3 and a control system as shown in FIG. The developing sleeve drive motor driver 107 shown in FIG.
When the transistors 25 and 26 are in the conductive state, the drive motor M rotates forward (rotates in the same direction as the developing operation) and the transistors 27 and 28 are in the conductive state. Drive motor M is rotated in the reverse direction. The control system shown in FIG. 4 includes a controller 101, a memory 103, and an I / O port 105. The controller 101 performs arithmetic operations and logical operations. The controller 101 puts the developing sleeve drive motor driver 107 under its control through the I / O port 105. The controller 101 outputs a predetermined drive command signal to each of the transistors 25 to 28 forming the developing sleeve drive motor driver 107 based on various data stored in the memory 103. The memory 103 stores various data. The data stored in the memory 103 is, for example, time data when the developing sleeve drive motor M is normally / reversely rotated.

In the structure described above, the developing sleeve 46b is first rotated in the normal direction under the control of the control system shown in FIG. 4, and the developer collecting sleeve 50 is moved in the direction of arrow E in FIG. It can be rotated. The developer on the outer peripheral surface of the developing sleeve 46b near the magnetic pole N ₁ is
_{4 is} separated from the outer peripheral surface of the developing sleeve 46b by the action of the magnetic field generated from _4, and the developer recovery container 12 is moved along the arrow E direction.
Fall inside. At this time, the developer is conveyed to the side of the developing sleeve 46b by the rotation of the screw 44, but the developer moving to the magnetic pole S ₂ side on the outer peripheral surface of the developing sleeve 46b and the developer moving to the magnetic pole S ₁ side. To be separated. Here, if the positional relationship between the magnetic pole of the magnetic pole roller 46a and the magnetic pole of the magnet 51 is as shown in FIG. 8, it corresponds to the magnetic pole S ₁ on the outer peripheral surface of the developing sleeve 46b. The movement of the developer from the part to the part corresponding to the magnetic pole S ₂ is
It is extremely difficult due to the action of the repulsive magnetic field and the self-weight of the developer. Therefore, as shown in FIG. 9, the complete amount of the developer from the portion on the outer peripheral surface of the developing sleeve 46b corresponding to the magnetic pole S ₁ is completely removed. It is impossible to separate them. The state shown in FIG. 9 shows the end of the developer collecting operation shown in FIG.

FIG. 10 shows the second developer recovery state. The developing sleeve 46b reversely rotates in the direction of arrow F in FIG. 10 by the means described in FIGS. As a result, the developer stagnant on the outer peripheral surface of the developing sleeve 46b corresponding to the vicinity of the magnetic pole S ₁ is discharged into the developer collecting container 12. FIG. 11 shows the state at the end of the second developer recovery state shown in FIG. 10, and shows that the deteriorated developer has been completely recovered. The forward / reverse rotation time of the developing sleeve 46b is as described above.
A timer can be set in the memory 103, or an operator can provide a switch that can freely set the forward / reverse rotation time while confirming the recovery state of the developer.

Although the above description relates to a color copying machine including a rotary type developing device, the present invention is not limited to the above description and can be easily applied to various other image forming apparatuses. It is possible. Further, in the above description, it is assumed that the collected developer is a deteriorated developer, but the present invention is not limited to this, and it is possible to temporarily store it during maintenance of the developing device (for example, inspection of the density detection element). There is a case where a developer that can be used for a specific purpose is collected, and this case is also applicable.

As described above, according to the present invention, the structure of the developing device is not complicated, and the deteriorated developer contained in the developing device does not contaminate each part of the image forming apparatus. It is possible to provide an image forming apparatus having a developing device which can be easily and surely collected and which does not damage each part in the image forming apparatus including the image carrier.

[Brief description of drawings]

FIG. 1 is an overall longitudinal sectional view showing a color image forming apparatus according to an embodiment of the present invention. FIG. 2 is a partial vertical sectional view showing the structure of the developing device according to the embodiment of the present invention. FIG. 3 is a circuit configuration diagram of a developing sleeve drive motor driver according to an embodiment of the present invention. FIG. 4 is a block diagram showing a configuration of a control system according to an embodiment of the present invention. FIG. 5 is a diagram showing the developer recovery container and each developing device at the start of the developer recovery operation according to the embodiment of the present invention. FIG. 6 and FIG. 7 are views showing the relative positional relationship between the developer recovery container and each developing device during the developer recovery according to the embodiment of the present invention. FIG. 8 is a diagram showing a first developer recovery state according to an embodiment of the present invention. FIG. 9 is a diagram showing a state at the end of the first developer collecting state according to the embodiment of the present invention. FIG. 10 is a diagram showing a second developer recovery state according to an embodiment of the present invention. FIG. 11 is a diagram showing a state at the end of the second developer collecting state according to the embodiment of the present invention. 1: Photosensitive drum 4: Developing device 46: Developing roll 46a: Magnet roller 46b: Developing sleeve 100: Rotating body

Claims (1)

[Claims] 1. A developer carrying member containing a first magnet having a repulsive magnetic pole and carrying a developer; a developing device having the developer carrying member and facing the image carrying member at a developing position; A developer collecting device that collects the developer in the developing device into a collecting container at a developer collecting position apart from the developing position, and the developing device moves between the developing position and the developer collecting position. In the image forming apparatus, the first magnet is stationary, the developer collecting device has a developer carrying body containing a rotating second magnet, and the developer carrying body in the developing device collects the developer. An image forming apparatus capable of rotating in any direction at any time.