JPS61238073A - One-component developing device - Google Patents

Abstract

PURPOSE:To prevent foreign matter in a developer and a toner flocculate lump from staying on the upstream side of a doctor blade by separating the doctor blade from a sleeve intermittently. CONSTITUTION:The doctor blade 8 which extends in parallel to the axis of rotation of the developing sleeve fitted rotatably on a magnet holding shaft 4 is provided at the top of the sleeve 5 and the blade 8 is moved up and down through an electromagnetic plunger 9. When this plunger 9 operates to separate the blade 8 from the sleeve 5, the foreign matter 7 in the developer and the toner-flocculated lump pass under the blade 8 together with the developer 6. At this time, developing operation is stopped and a developing device 2 is rotated to separate a photosensitive body 1 and the sleeve 5 from each other, so that the developer 6a returns to a developer storage part smoothly. Thus, the foreign matter 7 in the developer and the toner-flocculated lump are prevented from staying on the upstream side of the blade 8.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a developing device for developing an electrostatic latent image with a one-component developer.

(b) Conventional technology In electrostatic recording devices such as electrophotographic copying machines and facsimile machines, an electrostatic latent image of an image to be recorded is formed on a charge retention member, and this electrostatic latent image is developed using a developer containing toner. It is developed into a visible image. A device that can be used for this development is a developing device, and various types of developing devices are currently known.

By the way, the developer that can be used in this type of developing device is as follows:
Magnetic powder (carrier) such as iron powder and colored synthetic resin powder (
There are two-component developers consisting of toner) and one-component developers consisting of synthetic resin mixed with coloring material and magnetic powder.Recently, the latter has begun to attract attention due to its maintenance-free nature. - Since the component developer does not contain a carrier, it consists only of particles having a smaller particle size than the two-component developer. Therefore, the distance between the doctor blade and the sleeve is also o, smm.
This is significantly smaller than the approximately 1 to 5 m in the case of a two-component developer. Therefore, -component developer has a tendency to clump by itself, and pressure is applied at the narrow regulating part, so it clumps even more easily.Since the gap between the developing sleeve and the doctor blade is narrow, slight clumps (toner aggregates) occur. )
However, there is a problem in that it can become clogged and cause uneven density.

A similar problem can also occur due to foreign matter such as lint mixed into the developer. If a lump of developer is mixed in, it will get stuck between the doctor blade and the sleeve, and the developer will not be transported to that area, causing a problem where development will not be performed (it will appear as a white vertical line on the lobby). This phenomenon is particularly likely to occur when an insulating toner is used as the developer.

(c) Problems to be solved by the invention In the conventional developing device as described above, methods of scraping off the developer from the developing sleeve or stirring the developer are used to prevent the formation of lumps. However, countermeasures against clogging include removing the developer from the developer container during maintenance and passing it through a sieve, or removing the developer from the recording device each time and cleaning the developer transport section by hand to remove foreign objects. However, such an operation is extremely troublesome, and the greatest advantage of component developers, which is maintenance-free, is lost, and the efficiency of recording work is significantly reduced. There's a problem. Therefore, a method has been proposed in which a cleaning member is provided on the doctor blade and the cleaning unit is operated from the outside to easily remove foreign substances (Japanese Patent Application No. 168069/1982).

However, even with the foreign matter removal method using the cleaning member, there is a problem in determining the timing and frequency of implementing this method, and the operation is cumbersome because it is manually operated by a person.

Therefore, it has been proposed to provide a rotary roller with brushes and projections on the upstream side of the doctor blade to prevent developer agglomeration (Japanese Patent Laid-Open No. 58-1509
No. 84).

However, the provision of brushes and rotating rollers complicates the overall structure of the developing device, and there is also the possibility that the developer may condense on the protrusions, making it impossible to deagglomerate the toner agglomerates.

<2) Means for Solving the Problems The present invention has a cylindrical developing sleeve rotatably fitted onto a magnet, and a doctor blade extending in a direction parallel to the rotational axis of the developing sleeve on the circumferential side of the developing sleeve. This is a one-component developing device configured such that the doctor blade is intermittently separated from the developing sleeve.

(E) Function The doctor blade is configured so that it can be separated from the sleeve intermittently, so even if toner aggregates or foreign matter are mixed in the developer, they will always remain on the upstream side of the doctor blade. That is, while the doctor blade is separated from the developing sleeve, toner aggregates and the like pass through the doctor blade and return to the developer container, where they are stirred.

(f) Embodiments All drawings show embodiments of the present invention, and
The figure shows the first embodiment, and FIGS. 4 to 6 are configuration diagrams showing the second embodiment.

Parts common to these embodiments are designated by common reference numerals.
A description of each embodiment will be omitted.

(1) is a photoreceptor, on the surface of which an electrostatic latent image is formed by means not shown. (2) is the main body of the developing device, which includes a cylindrical magnet holding shaft (4) in which a plurality of tombstones (3) are embedded in the surface thereof, and a magnet holding shaft (44) that is rotatably fitted into the magnet holding shaft (44). A non-magnetic developing sleeve (5) is installed inside. (6) is a -component developer, and (7) is a foreign substance mixed therein.

A doctor blade (8) is provided on the top of the developing sleeve (5) and extends in a direction parallel to the rotational axis of the developing sleeve (5), and this doctor blade (8) is connected to the electromagnetic plunger (9). It is constructed so that it can be moved up and down.

Further, the developing device main body (2) is swingably held at the upper part, and the developing sleeve (5) is configured to be able to come into contact with and separate from the photoreceptor (1).

In this embodiment, the magnet holding shaft (4) is fixed, and only the developing sleeve (5) is configured to rotate counterclockwise.

When the electromagnetic plunger (9) operates and the doctor blade (8) separates from the developing sleeve (5), the foreign matter (7) and toner aggregates in the developer (6) are removed from the developer (6). 6) and pass through the bottom of the doctor blade (8). At this time, when the developing operation is stopped and the developing device (2) is slightly rotated to separate the photoreceptor (1) and the developing sleeve (5), the developer (6a) smoothly returns to the developer storage section. (See Figures 2 and 3).

Note that the photoreceptor (1) and the developing sleeve (5) do not necessarily need to be separated from each other, but it goes without saying that the developer (6a) will return more smoothly if they are separated.

The difference between the second embodiment and the first embodiment is that the magnet (3)
... are embedded in the rotating shaft (10) so that different magnetic poles appear on the surface side, and the doctor blade (
11) be fully magnetized, and the electromagnetic plunge~(
9) does not exist. Furthermore, the developing sleeve (5)
does not necessarily rotate.

The doctor blade (11) in this embodiment is held movably up and down by means not shown, so the doctor blade (11) is held by a magnet (
3) When the rotary shaft (10) in which... is embedded rotates, the magnetic poles of the doctor blade (11) and the magnet 3)...
・It will move up and down depending on the difference in magnetic poles. That is,
If the magnetic poles of the doctor blade (11) and the magnets (3) are different, an attractive force acts between them (3) and (11), causing them to press against each other, and the magnetic poles of the doctor blade (11) and If the magnetic poles of the magnets (3) are the same, both (3)
) (11) A repulsive force acts between them and they separate from each other. Therefore,
When the rotating shaft (10) rotates and the doctor blade (11) moves up and down during the developing operation, foreign matter (
7) etc. pass through the lower part of the doctor blade (11) and return to the developer storage section.

Note that the rotating shaft (10) does not necessarily need to rotate only in one direction, and may swing in the left-right direction.

(g) Effects of the Invention In the present invention, since the doctor blade is intermittently separated from the sleeve, foreign matter in the developer and toner agglomerates do not remain on the upstream side of the doctor blade.

In particular, if a plurality of foundation stones are embedded in a cylindrical rotating shaft so that different magnetic poles appear on the surface side, and the doctor blade is magnetized, it is possible to move the doctor blade 1 up and down with an extremely simple structure. This can contribute to weight reduction and cost reduction.

[Brief explanation of the drawing]

1 to 3 are configuration diagrams showing different aspects of the first embodiment of the present invention, and FIGS. 4 to 6 are block diagrams showing different aspects of the first embodiment of the present invention.
FIG. 3 is a configuration diagram showing different aspects of the embodiment. (1)...Photoreceptor, (2)...Developing device main body, (3
)...Magnet, (4)...Magnet holder, (5)...
Developing sleeve, (6)...Developer, (7)...Foreign matter, (8) (11)...Dr.Frede, (9)...
・Electromagnetic plunger, (10)... Rotating shaft.

Claims (1)

[Claims] 1. A one-component developing device in which a cylindrical sleeve is rotatably fitted onto a magnet, and a doctor blade extending in a direction parallel to the rotational axis is pressed against the circumferential side of the sleeve. A one-component developing device comprising: means for intermittently separating the doctor blade from the sleeve. 2. The one-component developing device according to claim 1, wherein a plurality of magnets are embedded in a cylindrical rotating shaft so that different magnetic poles appear on the surface side, and the doctor blade is magnetized. 3. The means for separating the doctor blade from the sleeve is as follows:
The one-component developing device according to claim 1, which is configured to operate only during non-developing time.