JPS62127780A - Developing device - Google Patents

Abstract

PURPOSE:To prevent the sticking of a developer unnecessarily on a photosensitive body at the time of non-developing by rotating reversely a rotation sleeve while the main pole of a magnetic roller is separated from the circumferential surface of the photosensitive body at the time of the non-developing. CONSTITUTION:While a main pole 13 of a magnet roller 10 is separated from the peripheral surface of a photosensitive body drum 5 at the time of non- development, a rotating sleeve 9 is reversely rotated. For such a reason, the developer located at a developing part is shifted to the main pole 13 side accompanying the rotation of the rotating sleeve 9, the conveying of the developer is stopped by the existence of a cleaning blade 7, and the developer is not supplied newly to the developing part. As the result, the developer does not exist at the developing part of a developing roller 4 facing to the peripheral surface of the photosensitive body drum 5, and the reduction of the picture quality due to the sticking of the developer at the surface of the photosensitive body drum 5 at the time of the non-developing can be prevented.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an improvement in a developing device for developing an electrostatic latent image formed on a photoreceptor of an image forming apparatus such as an electrostatic copying machine. .

(Prior Art) Conventionally, in a developing device equipped with a developing roller that rubs developer to develop an electrostatic latent image on a photoreceptor, developer is supplied from the developing roller to the photoreceptor during non-development. If this happens, there is a problem in that unnecessary developer adheres to the photoreceptor and image quality deteriorates.

Especially each along the circumferential surface of the photoreceptor? It is configured to perform multicolor development by disposing a plurality of developing devices containing different color developers, and each developing device is frequently switched between a developing state and a non-developing state. Therefore, it is possible to properly develop the electrostatic latent image during development, and
It is desired to be able to effectively prevent unnecessary developer from adhering to the photoreceptor during non-development, and to be able to quickly switch between the developing state and the non-developing state.

For this reason, for example, as shown in Japanese Unexamined Patent Application Publication No. 58-34469, the magnetic roller disposed inside the rotating sleeve of the developing roller is displaced by about 1800 rotations, and the magnetic pole such as the main pole of the magnetic roller is There are some devices in which unnecessary developer is prevented from coming into contact with the photoreceptor by separating it from the circumferential surface of the photoreceptor. Hf of this configuration
In the fl, all the magnetic poles of the magnet roller are located in the developer container during non-development to prevent the supply of developer to the photoreceptor, so that the magnetic poles do not face the photoreceptor during non-development. The magnetic pole cannot be disposed over more than half the circumference of the magnetic roller to prevent the problem from occurring, and as a result, there is a problem that the developer conveyance force during development tends to be insufficient.

Furthermore, in order to prevent deterioration in image quality due to lack of developer at the start of development, it is necessary to quickly and smoothly transport the developer for forming the magnetic brush from the developer container to the developing section. For this reason, in conventional devices, a cleaning blade for removing the developer remaining on the rotating sleeve of the developing roller is provided so as to be able to approach and separate from the surface of the rotating sleeve. The cleaning blade is separated from the surface of the rotating sleeve and the magnetic pole is moved from inside the developer container to a position facing the developing section of the photoreceptor, which poses a problem of complicating the structure.

(Objective of the Invention) The present invention has been made in order to solve the above-mentioned problems.It has a simple structure, can secure sufficient developer conveying force during development, and does not need to be attached to the photoreceptor during non-development. To provide a developing device that can prevent undesirable toner from being supplied.

(Structure of the Invention) The present invention includes a developer container containing a developer, a developing roller provided facing the circumferential surface of a photoreceptor, and regulating the brush height of a magnetic brush formed on the developing roller. and a cleaning blade that removes developer remaining on the developing roller after development. In a developing device constituted by a moving rotating sleeve and a magnet roller having a main pole facing the circular surface of a photoreceptor during development and rotatably disposed within the rotating sleeve, one It is provided with a rotation means for rotationally displacing the magnet roller in a direction to separate the recording main pole from the circumferential surface of the photoreceptor, and a reversing means for reversing the direction of rotation of the rotary sleeve during non-development.

According to the above configuration, the rotating sleeve rotates in the opposite direction during non-development, so that the surface of the rotating sleeve passes through the cleaning blade section and then reaches the developing section facing the circumferential surface of the photoreceptor, so that the developer reaches the developing section. Since the toner is no longer conveyed and the sovereignty of the magnet roller is separated from the circumferential surface of the photoreceptor, unnecessary toner is no longer attached to the circumferential surface of the photoreceptor during non-development.

(Embodiment) In FIG. 1, two developing devices 1a and 1b are disposed above and below in the circumferential direction of a photosensitive drum 5 in an electrostatic copying machine. The developing devices 1a and 1b include a developer container 2 containing a two-component developer consisting of toner and carrier;
A toner hopper 3 containing replenishment toner is provided, and a developing roller 4 disposed within the developer container 2 is installed to face the photoreceptor drum 5. In addition, an @itch roller 6.6 is disposed in the developer container 2 in parallel with the developing roller 4, and the developer after being used for development is transferred to the developing roller along the circumferential surface of the developing roller 4. A cleaning blade 7 that removes the magnetic brush from the circumferential surface of the magnetic brush and conveys the magnetic brush 4, and a doctor blade 8 that regulates the height of the magnetic brush. The developing devices 1a and Ib each contain a developer of a different color in each developer container 2.2. The electrostatic latent image formed in the image forming apparatus is configured to perform multicolor development of an electrostatic latent image.

The developing roller 4 includes a cylindrical rotating sleeve 9 that is rotationally driven by a driving means, and a magnet roller 10 that is rotatably disposed within the rotating sleeve 9.
A pumping pole 11 is provided on the outer periphery of this magnet roller 10.
The magnetic poles such as the transport pole 12, the main pole 13, and the transport pole 14 are magnetized clockwise at predetermined intervals. As shown in FIG. 2, the rotating sleeve 9 has one end attached to the support shaft 1.
5 is supported by the side plate 16 of the developer container 2, and its loose end is supported by the drive shaft 18 of the magnet roller 10 via a bearing 17. is fixed.

The magnetic roller 10 has one end supported by the rotating sleeve 9 via a bearing 20, and the other end supported by the side plate 21 of the developer container 2 via a drive shaft 18. A rotating means 22 consisting of a rotary solenoid or the like is attached. The rotating means 22 causes the main pole 13 of the magnet roller 10 to move into a developed state R facing the circumferential surface of the photoreceptor drum 5 (see developing device 1b at the bottom of FIG. 1), and the main pole 13 to the photoreceptor drum 5. 5
The magnet roller 10 is configured to be rotationally displaced between a non-developing state (see the developing device 1b in the upper part of FIG. 1) located near the doctor blade 8 and away from the circular surface of the magnetic roller 10.

Further, as shown in FIG. 3, the rotating sleeve 9 has the driven gear 19 in the first position. The drive gear 27
By being connected to, it can be rotated in forward and reverse directions.

That is, the transmission gear 25 is supported by a lever 28 so as to be able to swing while maintaining a meshing state with the drive gear 27, and by driving a solenoid 29 connected to the lever 28, the second It is configured to oscillate between a normal rotation state where it meshes with the intermediate gear 24 and a reverse rotation state where it meshes with the first intermediate gear 23.

In the above configuration, during development, the developer is drawn up by the pumping pole 11 of the magnet roller 10, and this developer adheres to the circumferential surface of the rotating sleeve 9, as shown in the developing amount 1b located at the bottom of FIG. A magnetic brush is thereby formed.

The magnetic brush has a portion facing the circumferential surface of the photoreceptor drum 5 that moves clockwise along with the circumferential surface of the rotating sleeve 8 that moves in the opposite direction to the drum circumferential surface, and is connected to the developing section, that is, the main pole 13. The electrostatic latent image is developed by rubbing the peripheral surface of the photoreceptor drum 5 at the corresponding position.

The developer remaining on the rotating sleeve 9 after passing through the developing section is removed by the cleaning blade 7 and guided onto the agitation roller 6, where it is agitated and mixed with the developer in the developer container 2 and moved to the developing roller 9. Supplied on the side. Furthermore, replenishment toner is appropriately replenished into the developer container 2 from within the toner hopper 3 via the replenishment roller 30 in accordance with the amount of toner consumed by the above-mentioned development.

Next, in order to shift from the developing state to the non-developing state shown in the developing device 1a located in the upper part of FIG. The main pole 13 is moved from the developing section to a position near the doctor blade 8, and the lever 28 of the reversing mechanism 26 is oscillated by two solenoids to change the direction of rotation of the rotary sleeve 9 from a normal rotation state to a reverse rotation state. Migrate.

In this way, when not developing, the main pole 13 of the magnet roller 10
Since the rotating sleeve 9 is rotated in the opposite direction while being separated from the circumferential surface of the photoreceptor drum 5, the developer located in the developing section moves toward the main pole 13 side as the rotating sleeve 9 rotates. At the same time, the presence of the cleaning blade 7 prevents the developer from being conveyed, thereby preventing new developer from being supplied to the developing section. As a result, no developer is present in the developing section of the developing roller 4 facing the circumferential surface of the photoreceptor drum 5, thereby preventing deterioration in image quality due to developer adhering to the surface of the photoreceptor drum 5 during non-development. can do.

Furthermore, since the cleaning blade 7 prevents the conveyance of the developer as described above, the above-mentioned main body 13 etc. does not necessarily have to be removed during non-development. Even if the entire i-pole is not located within the developer container 2, by separating at least the main pole 13 from the developing section, it is possible to prevent unnecessary developing agent from adhering to the photoreceptor drum 5. For this reason, the above magnetic pole arrangement? The magnetic roller 1 is less constrained by the l area.
There is no problem even if 6!1 poles are placed more than halfway around 0.
Therefore, it is possible to obtain a sufficient developer conveyance force during development. Therefore, unlike conventional devices, the cleaning blade is configured to be able to approach and separate from the circumferential surface of the developing roller in order to smoothly convey the developer for forming the magnetic brush to the developing section at the beginning of the developing BA period. There is no need to adopt a complicated structure such as a cleaning blade 7, and the structure of the apparatus can be simplified by making the cleaning blade 7 fixed.

In addition, in the reversing mechanism 26, when the transmission gear 25 makes one mechanical displacement, the driven gear 19 and the rotary sleeve 9 are appropriately reversed in the normal direction while the driving gear 27 is continuously rotated in a fixed direction. Since the configuration allows switching between the developing state and the developing state, there is no need to frequently repeat driving and stopping of the drive gear 27, which rotates at high speed, and this prevents the occurrence of photographing and failure of the device due to torque fluctuations. be able to.

Note that the specific configuration of each part can be modified in various ways, such as by using a drive motor capable of forward and reverse rotation in place of the reversing mechanism 26.

(Effects of the Invention) As explained above, in the present invention, by rotating the rotating sleeve in the opposite direction with the magnet roller's sovereignty separated from the circumferential surface of the photoreceptor during non-development, the circumferential surface of the rotating sleeve is exposed to the cleaning blade. Since the cleaning blade is configured so that the developer reaches the developing section facing the peripheral surface of the photoreceptor, the developer is no longer transported to the developing section, and the developer is not developed in the developing section. There will be no residual agent.

Therefore, it is possible to prevent unnecessary adhesion of developer onto the photoreceptor during non-development, and at the same time, there are fewer restrictions on the area in which the magnetic poles of the magnetic roller are arranged, and the magnetic poles can be arranged over more than half the circumference of the magnetic roller. By providing this, sufficient developer conveying force can be obtained during development without complicating the structure.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an embodiment of a developing device according to the present invention;
FIG. 2 is a sectional view taken along line If-II in FIG. 1, and FIG. 3 is a front view showing an embodiment of the rotary sleeve drive unit and reversing mechanism. 1a, 1b...Developing device, 2...Developer container, 4.
...Developing roller, 5...Photoconductor drum, 7...Cleaning blade, 8...Doctor blade, 9...
・Rotating sleeve, 10...Magnetic roller, 13・
...Main pole, 22... Rotating means, 26... Reversing mechanism. Patent applicant: Mr. Sanda Kogyo Co., Ltd.
Patent Attorney Etsushi Kotani Patent Attorney Cho 1) Masayuki Patent Attorney Yasuo Itaya Figure 1

Claims (1)

[Claims] 1. A developer container containing developer, a developing roller provided facing the circumferential surface of the photoreceptor, a doctor blade that regulates the height of the magnetic brush formed on the developing roller, and a a cleaning blade for removing developer remaining on the developing roller;
A rotating sleeve whose portion facing the circumferential surface of the photoconductor moves in a direction opposite to the circumferential surface of the photoconductor during development, and a main pole that faces the circumference of the photoconductor during development and is rotatable within the rotation sleeve. A developing device comprising: a rotating means for rotationally displacing the magnetic roller in a direction to separate the main pole from the circumferential surface of the photoreceptor during non-development, and a rotating means for rotating the magnetic roller during non-development. A developing device comprising a reversing mechanism for reversing the direction of rotation of a sleeve.