JPS6122374A - Developing device - Google Patents

Abstract

PURPOSE:To obtain good printing and recording by constituting a developing drum so that a magnet roll and a sleeve for surrounding its periphery can be rotated separately, bringing a soft magnetic plate installed to the sleeve close to a developing area at the time of development, and separating it at the time of non-development. CONSTITUTION:At the time of non-development immediately before starting development, a magnet roll 52 is moved by a prescribed angle in the direction as indicated with an arrow D by a magnet roll rotating motor 56, and a magnet notch part 61 of the roll 52 is positioned in the vicinity of a doctor blade 62. As a result, when starting development, the notch part 61 approaches the blade 62, it does not occur that a magnetic toner 63 whose bilstle tips have been made uniform by the blade 62 jumps over the notch part 61 by inertia by rotation of a sleeve 51 and is carried to a part 64 of a magnetic latent image of a recording drum 1, and a toner carried by a developing drum 59 does not exist, therefore, no toner pool is formed in the developing part, and a non-latent image part of the drum 1 is not contaminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a developing device of a magnetic recording device used as an output device of a computer, and particularly to a developing device near a developing area where a recording drum and a developing drum are close to each other during non-developing. By preventing the toner from being transported and preventing a large amount of toner from adhering to the developing drum, it also prevents the toner from adhering to the surface of the recording drum, causing unnecessary toner to cause unnecessary recording on printed paper. The present invention relates to a developing device which prevents the occurrence of printing and makes it possible to perform good print recording.

A developing drum, which has a magnetic layer forming a magnetic recording medium formed around it, forms a magnetic latent image on the magnetic recording medium of a rotating recording drum using a magnetic head, and is disposed close to and facing the recording drum. The magnetic recording device rotates and uses this developing drum to scrape up magnetic toner and apply the magnetic toner to the magnetic latent image formed on the magnetic recording medium for development. It's being used.

In the developing device used in such a magnetic recording device,
In the developing area where the recording drum and the developing drum are close to each other during non-development, when the toner is fed 1 m, the toner stays on the developing drum, and this staying toner adheres to the recording drum. The excess toner deposited on the recording drum is transferred onto the recording paper, making it impossible to record good prints. Therefore, this excess toner is prevented from being conveyed to the development area just before the magnetic development device is started, so that good prints can be achieved. There is a need for a developing device that can perform recording.

C. Prior Art] Such a conventional magnetic recording device will be explained with reference to FIG. As shown in the figure, a magnetic recording medium made of a magnetic material such as γ-Fe2O3 is formed around it, and a degaussing head 2 is used to form a uniform magnetic field on a recording drum l rotating in the direction of arrow A. After aligning the magnetization directions, a current is applied from the print recording generation circuit 5 to the magnetic head 3 made of ferrite or the like using an excitation coil 4 to form a magnetic latent image on the magnetic recording medium. The drum L is rotated, and the magnetic toner 8 in the developer tank 7 is scraped up using a magnet roll with a permanent magnet embedded inside and a developer roller 6 with a non-magnetic layer formed around it, and is formed on the magnetic recording medium 1. The developed toner image is transferred and recorded by being pressed against the recording paper 10 using the transfer roller 9, and then the excess toner adhering to the recording drum 1 is removed by a cleaner 11. removed.

There are two types of developing devices used in such magnetic recording devices: a sleeve rotation type as shown in FIG. 6, and a magnet roll rotation type as shown in FIG.

FIG. 6 shows a sleeve rotation type developing device I2. As shown in the figure, this developing device I2 is provided with a magnet cutout 13 in which no permanent magnet is embedded, a magnet roll 14 in which the permanent magnet is embedded, and an aluminum layer surrounding the magnet roll 14. The developing drum 16 consists of a sleeve 15 made of a non-magnetic layer, and the magnet roll 14 is fixed in such a state that the magnet notch 13 is closest to the recording drum 1, and only the surrounding sleeve 15 is in the direction of arrow B. Developing device 1
The magnetic toner 17 inside 2 is scraped up.

The magnetic toner 17 is aligned by a doctor blade 18 made of a thin copper plate disposed close to the developing drum 16 so that the height of the spikes of toner is constant. The reason why the magnet notch 13 is provided in this way is to prevent the magnetic latent image 20 formed on the magnetic recording medium I9 of the recording drum 1 from being destroyed by the permanent magnet of the magnet roll 14. Even if this magnet notch 13 is provided, the doctor blade 1
8 and the magnet notch 13, the magnetic toner 17 whose tip height is aligned with the doctor blade 18 without being affected by the magnet notch 13.
The magnet notch 13 is not caused by the permanent magnet of the magnet roll 14, but by inertia due to the rotational movement of the sleeve 15.
The magnetic latent image 2o is reached and development can be performed.

On the other hand, in the magnet roll rotation method, the magnet roll 21 rotates in the direction of arrow C as shown in FIG. It is attached to the surface of the sleeve 22 using an adhesive or the like so as to be parallel to the rotation axis of the magnet roll 21. In this way, the soft magnetic plate 2
3 is attached because a magnetic field is generated between this soft magnetic plate 23 and the magnet roll 21, and this soft magnetic plate 23
The distribution of the magnetic field becomes steep at the position where the magnetic latent image 20 is pasted, and even if the distance between the recording drum 1 and the developing drum 24 is increased in this area to prevent the magnetic latent image 20 from being destroyed by the permanent magnet of the magnet roll 21. The magnetic toner 25 conveyed by the magnet roll 21 is stacked on this portion to form a toner pool.

Further, a doctor blade 26 is also provided in the same manner as in the sleeve rotation method, so that the heights of the spikes of toner 25 are made to be the same.

On the other hand, in addition to such a developing device, two developing devices are provided as shown in FIG. Using a rotation method, the particle size of the second magnetic toner 34 used in the second developing device 32 is made larger than the particle size of the first magnetic toner 33 used in the first developing device 31. After developing the magnetic latent image on the recording drum 1 with a magnetic toner, the magnetic recording medium on the recording drum 1 is developed with a second magnetic toner, and a non-magnetic latent image other than the magnetic latent image developed with the first toner is developed. There is a two-stage developing device that uses a second toner to remove a first toner adhering to a latent image area.

[Problem that the invention seeks to solve]

However, in such a developing device, whether it is a sleeve rotation method, a magnet roll rotation method, or a two-stage development method, there is always a magnetic field between the magnet roll and the recording drum 1. Therefore, magnetic toner does not adhere to the surface of the developing drum even when the magnetic recording device is stopped, the developing device is stopped, and toner transport is stopped, that is, even when not developing. are doing.

Therefore, when the magnetic recording device is driven to start development, linear streaks are formed on the surface of the developing drum by the toner adhering to the developing drum, and these linear streaks are formed on the recording drum 1. There was a problem in that linear streaks caused by the toner adhered to the recording drum were further transferred onto the recording paper, making it impossible to perform good printing and recording.

In order to solve this problem, conventionally, as shown in FIG. 9, when starting development, the developing device 41 is driven using an eccentric cam 42, etc., and the developing drum 43 is moved away from the recording drum 1. The drum 43 is rotated to prevent the toner staying in the developing area close to the recording drum 1 and the developing drum 43 from adhering to the magnetic latent image formed on the recording drum, and the developing device is driven. After some time has elapsed, the developing drum 43 is returned to its normal position and development is performed. Such a device can be applied to a sleeve rotation type or a magnet roll rotation type, and can also be applied to a first stage developing device of a two-stage development type.

However, a device using such an eccentric cam has the problem that it is complicated and the device itself is large-scale.

Another drawback is that it takes too much time to move the developing drum 43 from the recording drum 1 using the eccentric cam.

[Means for solving problems]

The above-mentioned problem consists of a rotating recording drum that is surrounded by a magnetic recording medium on which a magnetic latent image is formed, and a developing drum that is placed opposite to the recording drum and that conveys the magnetic toner. In a magnetic recording device that develops the magnetic latent image by conveying magnetic toner to a developing area where a recording drum and a developing drum are close to each other and depositing the magnetic toner on a magnetic latent image, the developing drum surrounds a magnetic roll and its periphery. The sleeve is configured to be rotatable separately, and during development, the notch of the magnet roll or the soft magnetic plate installed on the sleeve is brought close to the development area, and when not in development, the notch of the magnet roll or the sleeve is placed close to the development area. This is achieved by the magnetic recording apparatus of the present invention in which the upper soft magnetic plate is isolated from the development area.

[Effect]

That is, in the magnetic recording device of the present invention, the developing drum is provided with a mechanism that allows the magnetic roll and sleeve of the developing drum to rotate separately, and when the sleeve rotation method is used at the start of development, the magnet cutter of the magnetic roll is In order to prevent unnecessary toner from being conveyed to the developing area of the developing drum, the notched portion or the soft magnetic plate when using the magnet roll rotation method are separated from the developing area during non-development immediately before the start of development. This is what I did.

The device can be used with either the sleeve rotation method or the magnet roll rotation method, thereby expanding the usable range of the device.

〔Example〕

Hereinafter, one embodiment of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view of a developing drum in a developing device of the present invention which can be used for either the sleeve rotation method or the magnet roll rotation method. In the figure, 51 is a sleeve, 52 is a magnet roll, and 53 is for sleeve rotation. A rotating shaft 54 is a rotating shaft for rotating a magnet roll, 55 is a motor for rotating a sleeve, and 56 is a motor for rotating a magnetic roll. The developing drum 59 is rotated by a bearing 58, and the developing drum 59 is provided with a bearing 60 for driving a rotating shaft for rotating the magnet roll.

By rotating the sleeve rotation motor 55, only the sleeve 51 is rotated, and by driving the magnet roll rotation motor 56, only the magnet roll 52 is rotated.

The case where the developing device of the present invention is used to perform development using the sleeve rotation method will be described with reference to FIG. 2.

FIG. 2 is a schematic diagram showing the state immediately before the start of development, that is, during non-development. When developing using the developing device of the present invention as shown in the figure, just before driving the developing device, the magnet shown in FIG. The roll rotation motor 56 is driven, and the second
As shown in the figure, the magnet roll 52 is moved by a predetermined angle in the direction of the arrow so that the magnet notch 61 of the magnet roll 52 is in a position close to the doctor blade 62. Then, at the start of development, the magnet notch 61 is placed close to the doctor blade 62, and the magnetic toner 63 whose tips are aligned by the doctor blade 62 is moved through the magnet notch by inertia caused by the rotation of the sleeve 51. Since the toner is not carried over the area to the magnetic latent image location 64 of the recording drum 1 and there is no toner carried by the developing drum 59, no toner pool is formed in the developing area. The non-latent image portions of the recording drum are no longer contaminated, the surface of the recording drum is kept clean, and the recording paper on which transfer and recording is performed is no longer stained by unnecessary toner. Thereafter, when the magnetic latent image formed by the magnetic head shown in FIG. 1 reaches the developing area, the magnet cutout of the magnet roll 52 is brought close to the developing area as shown in FIG. 6, and the developing operation is performed. .

Next, the case of developing using the developing device of the present invention in a magnet roll rotation system will be described with reference to FIG.

This state shows the state immediately before the start of development, and is a state during non-development.

When developing using the developing device of the present invention as shown in the figure, the sleeve rotation motor 55 shown in FIG.
1 in the direction of arrow E to bring the soft magnetic plate 65 close to the doctor blade 62. Then, in the developing area where the developing drum 59 and the recording drum 1 are close to each other, a steep distribution of the magnetic field cannot be obtained between the soft magnetic plate 65 and the magnet roll 52, so the toner 63 is exposed to this steep magnetic field in this developing area. Distribution.

As a result, the condition of toner pools rising up in a stacked manner is no longer observed, and the toner 63 no longer reaches the magnetic latent image 64 and is not developed (therefore, the surface of the recording drum 1 is also kept clean). .

Thereafter, when the magnetic latent image reaches the developing area, the sleeve is moved so that the soft magnetic plate moves into the developing area as shown in FIG.

Further, in the case of a two-stage developing device as shown in FIG. 8, the magnet notch 12 of the magnet roll 13 and the soft magnetic plate 23 on the sleeve 22 are moved in the same direction and by the same angle. each doctor blade 17
．． 26, so in this case, as shown in FIG.
, and the rotating shaft 53 of the sleeve are preferably driven by the same motor 71 and by a belt 72.

Further, as the motors 55, 56, and 71 for driving the magnetic drum of the present invention described above, it is preferable to use a pulse motor or a DC motor with an absolute encoder whose rotation angle can be controlled.

〔Effect of the invention〕

As described above, according to the developing device of the present invention, a toner pool is not formed at the position where the developing drum and the recording drum are closest to each other at the start of development, so unnecessary toner is not attached to the developing drum, and therefore recording is possible. Since unnecessary toner is not deposited on the drum, the surface of the recording medium is kept clean, resulting in the effect that good printing and recording can be performed.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the developing drum of the developing device of the present invention, Fig. 2 is a sectional view showing the non-developing state when the developing drum of the present invention is used in a sleeve rotation system, and Fig. 3 is a sectional view of the developing drum of the developing device of the present invention. FIG. 4 is a cross-sectional view showing the non-developing state when the developing drum of the present invention is used in a magnet roll rotation system. FIG. 4 shows the state when the developing device of the present invention is used as a two-stage developing device. Schematic diagram: Figure 5 is a schematic diagram of a conventional magnetic recording device; Figure 6 is a schematic diagram of a sleeve rotation type developing device during development; Figure 7 is a schematic diagram of a magnetic roll rotation type developing device during development. , FIG. 8 is a schematic diagram of a conventional two-stage developing device, and FIG. 9 is a schematic diagram of a conventional developing device. In the figure, 51 is a sleeve, 52 is a magnet roll, 53 is a sleeve rotation shaft, 54 is a magnet roll rotation shaft, 55 is a sleeve rotation motor, 56 is a magnet roll rotation motor, 57 is a bearing, 58. 60 is a bearing, 59 is a developing drum, 61 is a magnet notch, 62
is a doctor blade, 63 is a toner, 64 is a magnetic latent image forming area, 65 is a soft magnetic plate, 71 is a motor, 72 is a belt, D is an arrow indicating the rotation direction of the magnet roll, and E is an arrow indicating the rotation direction of the sleeve. It is. Figure 4 Figure 5 Figure 6 Figure 117

Claims (1)

[Claims] a rotating recording drum surrounding a magnetic recording medium on which a magnetic latent image is formed;
A magnetic recording device that includes a developing drum that conveys magnetic toner, and develops the magnetic latent image by conveying the conveyed magnetic toner to a developing area where a recording drum and a developing drum are in close proximity and depositing it on a magnetic latent image. The developing drum has a structure in which a magnet roll and a sleeve surrounding the magnet roll can be rotated separately, and during development, a notch of the magnet roll or a soft magnetic plate installed in the sleeve is brought into close proximity to the development area. A developing device characterized in that the notch of the magnet roll or the soft magnetic plate on the sleeve is isolated from the developing area when not developing.