JPS617863A - Dry developing device - Google Patents

Abstract

PURPOSE:To prevent staining in the device due to a developer which sticks unnecessarily on the surface of a latent image carrier by providing a developing roll movably from the latent image carrier by a specific extent. CONSTITUTION:The developing roll 2 is arranged at the opening part 5 of a developer storage tank 3 and its lower part is blocked with a stopper 41. The developing device 7 which consists of the storage tank 3 and developing roll 2 is so provided that it can be separated from the electrostatic latent image carrier 1 by the specific extent. In this constitution, the developing device 7 is put away from the carrier 1 when no development is performed and a permanent magnet 2b is rotated in the opposite direction of development to recover a developer in a developing area into the storage tank 3. Consequently, no unnecessary developer sticks on the carrier 1 and staining in the developer with the sticking developer is prevented.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention relates to an electrophotographic dry developing device. [Prior Art] Examples of the prior art of a dry developing device (hereinafter referred to as a developing device) include: Japanese Patent Application No. 57-177581 discloses that a developing roll is installed opposite to an electrostatic latent image carrier, and this developing roll is connected to a non-magnetic hollow sleeve (hereinafter referred to as sleeve) and the space inside this sleeve. The sleeve and the permanent magnets are configured to rotate rapidly relative to each other.

A developer storage tank is installed near the developer roll, and the development roll is located within the opening of the developer storage tank, with one circumference of the roll in contact with the developer stored in the developer storage tank. ing.

In this state, the developer magnetically attracted to the sleeve surface is discharged from the opening of the developer storage tank by the rotation of the sleeve, the rotation of the permanent magnet, or the rotation of both the sleeve and the permanent magnet.

The magnetic brush moves along the surface of the electrostatic latent image carrier and is conveyed to the development area, forming a magnetic brush to develop the electrostatic image on the electrostatic latent image carrier by rubbing.

A part of the developer in this development area adheres to the electrostatic image on the electrostatic latent image carrier for development, and the remaining developer is collected inside the developer storage tank through the opening of the developer storage tank. be done.

[Problem that the invention seeks to solve]

In the conventional dry-type developing device as described above, there are cases where the printing paper jams in the transfer section of the electrostatic latent image carrier during rubbing development using the developer in the developing area, or when the power to the device is cut off or the development ends. Sometimes, unnecessary developer adheres to the surface of the electrostatic latent image carrier due to the difference in timing between turning off the high power supply for primary charging and the bias power supply for development, and this adhered developer scatters or falls, causing electrostatic charge. There was a problem in that it adhered to the film or nails used to separate the printing paper from the latent image carrier, staining the printing paper.

In addition, since the rotation of the sleeve is mainly used to collect the developer on the surface of the sleeve in the developing area into the developer storage tank, the developer transporting capacity of the sleeve is greater than that of the permanent magnet. In addition, because the gap between the electrostatic latent image carrier and the sleeve is narrow, developer overflow occurs in a part of the developing area, and the developer in that area scatters or falls, resulting in excess developer on the electrostatic latent image carrier. This has become a problem as it adheres to the paper and stains the printing paper.

In addition, agglomerates tend to form near the opening of the developer storage tank.
There is also a problem in that this causes blocking development and deteriorates image quality.

[Means for solving problems]

In response to the above-mentioned problem, the present invention includes a permanent magnet having multiple poles disposed within a non-magnetic hollow sleeve.

An image roll is disposed in an opening of a developer storage tank to form a developing device, and the developing device is brought close to an electrostatic latent image carrier;
It is movable so that it can be moved further away.

[Effect]

By doing the above, when not developing, the developing device is moved away from the electrostatic latent image carrier, the magnetic brush is separated from the electrostatic latent image carrier, and the permanent magnet of the developing roll is rotated in the opposite direction to that during development. All the developer in the developing area on the sleeve is collected into the developer storage tank, and then the developing device is returned to its original position to ensure a minute gap between the regular developing roll and the electrostatic latent image carrier. Therefore, staining due to developer can be prevented.

〔Example〕

FIG. 1 is a sectional side view of a main part of a developing device showing an embodiment of the present invention, in which 1 is an electrostatic latent image carrier formed of a photosensitive material such as selenium, and 2 is an electrostatic latent image carrier 1. 2a is a non-magnetic hollow sleeve (hereinafter referred to as sleeve) that constitutes the developing roll 2;
The developing roll 2 also includes a plurality of permanent magnets that extend in the axial direction and have N and S poles alternately in the circumferential direction in the hollow of the sleeve 2a, and the sleeve 2a and the permanent magnets 2b are opposite to each other. It has a rotatable structure. 3 is a developer storage tank,
It has an opening facing the electrostatic latent image carrier 1, and the developing roll 2 is disposed therein. 4 is developing roll 2
A stopper is provided on the developer storage tank 3 so as to contact the developing roll 2 over the entire length in the axial direction at the bottom.The stopper 4 is made of a flammable material such as felt or polyurethane rubber. Therefore, below the developing roll 2, the developer storage tank 3 and the outside are closed off.

5 is a gap between the developer storage tank 3 and the upper part of the developing whirl 2, and is an opening for discharging and recovering the developer, which will be described later; 6 is the developer stored in the developer storage tank 3; 7 is the developing roll 2; This developing device includes a developer storage tank 3 having a developer storage tank 3, and the developing device 7 is movable in the directions of arrows H and I facing the electrostatic latent image carrier 1, and the developing device 7 is movable in directions of arrows H and I facing the electrostatic latent image carrier 1 and the developing roll 2. minute distance F
can be changed.

The developer 6 stored in the developer storage tank 3 is supplied through an upper replenishment port (not shown) of the developer storage tank 3, and the replenishment port opens only when supplying, and is normally tightly closed. There is. Therefore, the developer 6 contained in the developer storage tank 3 is discharged to the outside only through the opening 5.

The developing device of this embodiment has the above-mentioned configuration.
Next, its operation will be explained.

Before the start of development, the developer 6 does not adhere to the development area, which is the surface of the sleeve 2a facing the outside of the developer storage tank 3. , when development is started, first the permanent magnet 2b rotates in the direction of the arrow, so that the chain of developer 6 rotates in the opposite direction to the rotation of the permanent magnet 2b along with the change in the direction of the magnetic flux flow. do.

Therefore, the developer 6 stored in the developer storage tank 3 is transferred to the opening 5 of the developer storage tank 3. From there, it is discharged to the outer periphery of the sleeve 2 on the outside side in the direction of arrow C, passes through the developing area, and reaches the stopper 4.

A little later than the rotation of the permanent magnet 2b, the sleeve 2a starts rotating in the direction of arrow B at a lower rotation speed than the rotation of the permanent magnet 2b, and at the same time, the electrostatic latent image carrier 1 also rotates in the direction of arrow E. . Incidentally, as long as startup time is not an issue, it does not matter which one rotates first or at the same time.

In this way, when the sleeve 2a and the permanent magnet 2b rotate for a predetermined period of time, the developer 6 is conveyed to the developed image area on the surface of the sleeve 2a and forms the ears of the magnetic brush, and the length of the ears is balanced. becomes.

Next, the conveyance state of the developer 6 will be explained.

The lower layer of the developer 6 formed on the surface of the sleeve 2a is transported in the direction indicated by the arrow mainly depending on the rotation of the sleeve 2a and returns 9 into the developer storage tank 3 through the opening 5, while the upper layer The developer 6 is transported in the direction of arrow C while rotating on the surface of the sleeve 2a mainly depending on the rotation of the permanent magnet 2b, and is discharged from the opening 5 of the developer storage tank 3. The developer 6 in the upper layer eventually reaches the stopper 4, is drawn into the lower layer in a U-turn by the rotation of the permanent magnet 2b near the stopper 4, and then moves in the direction of the arrow depending on the rotation of the sleeve 2a. direction and returned to the developer storage tank 3.

In this manner, the magnetic brush of the developer 6 is maintained, and the electrostatic image formed on the electrostatic latent image carrier 1 is developed by rubbing.

In this development, since the developer 6 adheres to the electrostatic latent image carrier 1, the developer 6 in the development area from the opening 5 to the stopper 4 is consumed, but the developer 6 is removed from the developer storage tank 3 one after another. Since developer 6 is supplied, the amount of developer 6 in the developing area can be maintained constant, and the length of the ears of the magnetic brush can also be maintained in a balanced state.

The explanation so far is the same as that of the prior art described above.

Next, movement of the developing device 1 will be explained.

When the development is completed, the developing device 1 moves in the direction of arrow H to a position where the magnetic bluff of the sleeve 2a does not come into contact with the electrostatic latent image carrier 1. Next, the sleeve 2a and the permanent magnet 2b are stopped, and the permanent magnet 2b is rotated in the direction of arrow G, which is the opposite direction to the direction used during development, to transfer the developer 6 attached to the development area of the sleeve 2a into the developer storage tank 3. After the collection is completed, the permanent magnet 2b is stopped.

After that, move the developing device I in the direction of the arrow ■ and
The electrostatic latent image carrier 1 is stopped at the original position where a small distance F between the electrostatic latent image carrier 1 and the electrostatic latent image carrier 1 is properly maintained.

Therefore, during non-development, all the developer 6 is stored in the developer storage tank 3.
This prevents the equipment and surrounding area from becoming contaminated.

Next, a driving method for moving the developing device 7 will be explained with reference to FIG. 2.

FIG. 2 is a block configuration diagram showing a method of driving the developing device 7. When printing starts, the control circuit 8 outputs a signal 8a and a signal 8b, and the signal 8a rotates the shimo motor 9a, which transmits the gear belt, etc. The driving force is applied by the driving means 10B, 10b to the electrostatic latent image carrier 1. The signal is transmitted to the sleeve 2a and both rotate. On the other hand, the motor 9b is rotated by the signal 8b, and the permanent magnet 2b is rotated by the transmission drive means 10c such as a gear or a belt.

When such rotation starts, the developer 6 is immediately discharged from the opening 5 as described above, forming a magnetic brush in the development area reaching the stopper 4, and growing the ears to a predetermined length. maintain. In this state, the electrostatic image formed on the electrostatic latent image carrier 1 is developed by rubbing.

After the development is completed, a signal 8d is output from the control circuit 8.
The motor 9C is rotated by the signal 8d, and the developing device 7 is moved in the direction of the arrow H by the transmission drive means 10d such as a gear belt, and when it has moved to a predetermined position, the output of the signal 8d is stopped and the rotation of the motor 9C is stopped. After stopping the movement of the developing device 1, the output of the signals 8a and 8b from the control circuit 8 is stopped, the rotation of the motors 9a and 9b is stopped, and the electrostatic latent image carrier 1. The rotation of the sleeve 2a and the permanent magnet 2b is stopped.

When the rotation of the sleeve 2a and the permanent magnet 2b completely stops, a signal 8c is output from the control circuit 8, and the signal 8c causes the motor 9b to rotate in the opposite direction to that during development, and the transmission drive means 10C, such as a gear or a belt. As a result, the permanent magnet 2b rotates in the opposite direction to that during development. The output of the signal 8c is stopped after a predetermined period of time, and the rotation of the motor 9b is stopped and the permanent magnet 2b is also stopped. During the time from when this signal 8C is output until it is stopped, all the developer 6 in the developing area is collected inside the developer storage tank 3.

After that, the signal 8e is output from the control circuit 8, and the signal 8e
The transfer motor 9C rotates, and the developing device 7 is moved in the direction of the arrow ■ by the transmission drive means 10d such as gears and belts. When it reaches the original position, the signal 8e is stopped, and the rotation of the motor 9c is stopped and the developing device 7 is moved. Movement of the device 7 is also stopped.

The configuration and operation of this embodiment are as described above.

〔Effect of the invention〕

As described above based on the embodiments, the present invention makes the developing device movable and allows the developing roll to be separated from the electrostatic latent image carrier by a predetermined amount. The brush is not in contact with the electrostatic latent image carrier during non-development, and the developing device is moved during non-development to quickly separate the magnetic brush from the electrostatic latent image carrier, and then a magnetic brush is formed. Since all the developer can be collected in the developer storage tank, it is possible to prevent unnecessary developer from adhering to the surface of the electrostatic latent image carrier, and it is also effective in preventing contamination of the inside of the device and the printing paper that previously occurred. be.

In addition, since all the developer in the developing area on the sleeve surface is collected in the developer storage tank, there is no developer that falls or scatters due to shock or vibration when the device is started. It also has the effect of preventing staining of the inside of the device and the printing paper that may occur.

After the development is completed, the developer is collected into the developer storage tank, which has the effect of preventing blocking caused by agglomerations at the opening through which the developer passes.

As described above, according to the present invention, it is possible to provide a dry type developing device with a simple structure and good performance, and it can be usefully used in an electrophotographic device.

[Brief explanation of the drawing]

FIG. 1 is a sectional side view of a main part of a developing device according to an embodiment of the present invention, and FIG. 2 is a block diagram showing a method of driving the developing device. 1... Electrostatic latent image carrier 2... Developing roll 2a.
...Sleeve (non-magnetic hollow sleeve) 2b...Permanent magnet 3...Developer storage tank 4...Stock horn (5
... Opening 6... Developer 7... Developing device patent Applicant: Oki Electric Industry Co., Ltd. Agent Patent attorney: Takashi Kanakura, Nimen 1- 1... Electrostatic latent image carrier 2. ...Developing roll 2a...Sleeve 2b...Permanent magnet 3...Developer storage tank 4...Stopper 5...Opening 6...Developer 7...Developing device

Claims (1)

[Claims] 1. A developing roll consisting of a permanent magnet with multiple poles arranged inside a rotatable non-magnetic hollow sleeve is placed in the opening of the developer storage tank, its lower part is closed off from the outside by a stopper, and its upper part is closed off from the outside by a stopper. an opening for developer to pass through is formed in the non-magnetic hollow sleeve; In a dry type developing device, a magnetic brush is formed in a developing area by relative rotation of a permanent magnet and a permanent magnet, and the electrostatic image on the electrostatic latent image carrier is developed by sliding. It is movable relative to the electrostatic latent image carrier, and when not developing, the developing roll is moved from the electrostatic latent image carrier to separate the magnetic brush from the electrostatic latent image carrier, and the permanent magnet of the developing roll is rotated during development. A dry type developing device characterized in that the developer in the developing area is collected into a developer storage tank by rotating in the opposite direction.