JPH0419556Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-component developing device, and more particularly to a developing device that can effectively perform stirring and mixing of toner and carrier, especially left and right stirring, with a simple mechanism.

As magnetic brush development methods for electrostatic images, there are two known methods: a two-component development method that uses a developer consisting of a magnetic carrier and toner, and a one-component development method that imparts magnetism to toner particles and develops the toner particles alone. ing. The former has the advantage of being able to stably charge the toner, while the latter has the advantage of not having to worry about adjusting the toner concentration, and has better reproducibility of halftones than the former. ing.

In recent years, it goes without saying that the quality of copied images is high in contrast with sharp shading, and as a whole, it is required that intermediate tones be reproduced beautifully. Due to these requirements, it is effective to implement a one-component development method, but in general, the threshold value in terms of development conditions is determined by the magnetic attraction force of the developer to the sleeve and the Coulomb force to the electrostatic image. , and one-component type developers, because the magnetic material is dispersed in the fixing resin, the magnetic attraction force to the sleeve is weaker than that of the magnetic carrier, which causes fogging during development. The problem is that it is easy. To solve this problem, in conventional one-component developing systems, the length of the spikes is shortened to prevent fogging, but this can cause problems such as poor spike formation and reduced developer fluidity. Furthermore, during continuous use of a copying machine, even if foreign matter such as paper dust gets mixed into the magnetic brush, it tends to be difficult to form stable spikes.

For these reasons, research is being continued to improve the reproducibility of halftones by using a two-component developing method that can form a stable magnetic brush and sufficiently impart electric charge to the toner. As an example of this, a method is known in which the moving direction of a photosensitive drum having an electrostatic latent image and the moving direction of a magnetic brush are made the same (forward direction) in a developing area.
This method is more advantageous in reproducing halftones than reverse development because it allows for a longer development time and the friction force of the magnetic brush can be made smaller. It is also possible to prevent leakage of latent image charge due to

However, when adopting and implementing this forward direction development, there is a problem that the developing device itself becomes larger than the developing device that uses the reverse direction. The reason for this is that when mixing and stirring the toner and the magnetic carrier (hereinafter simply referred to as carrier),
In the case of reverse direction development, the developer whose toner has been consumed in the development area is scraped off from the sleeve surface with a scraper, and the scraped developer is mixed with the replenishment toner and the remaining developer in the developing device. The developer is sufficiently mixed and agitated by a roller, and then the agitated developer is held on the sleeve at a developer draw-up position located at the bottom of the sleeve, and then the spike length is regulated to a constant length by a panicle cutting member and then sent to the development area again. This is because while efficient mixing and stirring can be performed by forming two loops, it is difficult to form such a loop in the forward direction. That is, when a scraper is provided at the bottom of the sleeve to perform scraping, a storage area is provided below the position of the scraper in which the scraped developer accumulates, and a pumping mechanism is provided to pump the developer from this storage area to the upper part of the sleeve. This is because it is necessary.
Furthermore, even if the scraper were to be embedded in the developer instead of using this structure, it would only hinder the circulation of the developer within the developing device, and this would actually eliminate the merits of having the scraper. will no longer have. Furthermore, if the scraper is located above the sleeve, as in the case of reverse development, the loop becomes more complicated due to its relationship with the developer pumping position, and in either case, the overall device A problem arises in that the value becomes larger.

Furthermore, it has been known that by stirring the developer in the developing device from side to side, it is possible to prevent uneven toner concentration and to stabilize images. Various methods have been devised to stir the developer from side to side, but all of them involve adding a new side-to-side stirring mechanism to the conventional developing device, making the device complicated and large. That was the current situation.

The main object of the present invention is to provide a developing device that is more compact and capable of efficient mixing and agitation when carrying out such forward development.

Another object of the present invention is to provide a developing device that can efficiently stir the developer from side to side within the developing device.

According to the present invention, there is provided a hopper equipped with a toner supply roller, a developer conveying sleeve that rotates in a direction opposite to the rotational direction of the photoreceptor drum and has a magnet inside;
a stirring roller that rotates in the same direction as the developer transporting sleeve and is provided with a large number of stirring blades for frictionally charging the toner particles and uniformly mixing the toner and the carrier; formed on the developer transporting sleeve; A two-component developing device comprising: a brush cutting plate for regulating the brush length of a magnetic brush; a developer flow guide mechanism located above the stirring roller;
The stirring blade has a bent tip and is oriented in the rotating direction of the stirring roller, and each of the stirring blades is provided with a notch, and a guide is provided at one end of the notch, A spiral passage is formed on the stirring roller by these notches and guides, and the developer flow guide mechanism includes a partition plate and a large number of guide plates provided at predetermined intervals above and below the partition plate. These guide plates are oriented in a direction that makes an acute angle or an obtuse angle with the axial direction of the stirring roller,
In addition, the guide plates (first guide plates) provided above the partition plate and the guide plates (second guide plate) provided below the partition plate are provided substantially parallel to each other, and A two-component developing device is provided, characterized in that the orientation directions of a first guide plate and a second guide plate are in a positional relationship such that they intersect with each other.

A specific example of the present invention will be described below based on the accompanying drawings.

FIG. 1 is a cross-sectional view schematically showing a developing device of the present invention, in which a developing device generally designated by 3 is provided for a photosensitive drum 2 which rotates in the direction of arrow 1. As shown in FIG. The developing device 3 includes a non-magnetic cylindrical sleeve 6 which rotates in the direction of arrow 5 and has a magnet 4 inside which has a plurality of magnetic poles on its surface on the side of the photosensitive drum 2;
A developer stirring roller 8 having a plurality of stirring blades 7 on the opposite side of the sleeve 6 from the photoreceptor, a developer flow guide mechanism 9 located above the stirring roller 8, and a developer flow guide mechanism 9 from the developer flow guide mechanism 9 to the stirring roller 8. A toner hopper 11 equipped with a toner supply roller 10 is arranged above the position where the falling developer falls, and a brush cutting blade 12 is used to regulate the length of the magnetic brush formed on the sleeve 6 to a constant length. has been done.

In the developing device having this configuration, the developer can take the following flow. That is, the developer consisting of toner and carrier forms a magnetic brush 13 on the sleeve 6 by the built-in magnet 4, and this magnetic brush 13 is conveyed to the developing area 14 as the sleeve 6 rotates. Development area 14
Then, a toner image is formed according to the electrostatic latent image on the surface of the photoreceptor drum, and development is performed. After the development is completed, the magnetic brush 13 with the toner consumed moves to the developer scraping section 15 as the sleeve 6 rotates. The same magnetic poles of the magnets are adjacent to each other in the scraping portion 15, and due to this structure, the developer is subjected to a repulsive magnetic field and is removed from the sleeve.

Next, as the stirring blade 7 rotates 17 times, the scraped developer is transferred to the toner and guide mechanism 9 that are supplied from the hopper 11 located at the top.
The developer is conveyed to the developer pumping position 16 while being mixed and stirred together with the developer that has fallen from the developer. The developer magnetically attracted onto the sleeve 6 again at the pumping position 16 moves along the lower surface of the guide mechanism 9 as the sleeve 6 rotates. Next, a certain amount is regulated by the ear cutting blade 12, and a part is conveyed to the development area as the magnetic brush 13, and the remaining regulated part moves on the upper surface of the guide mechanism 9 and is again supplied to the stirring roller 8. In this way, a regular developer flow is formed in the developing device of the present invention.

The present invention improves the movement of the developer flow, and as a result of this movement, efficient mixing and agitation is performed, and the uniform mixing makes it possible to give sufficient charge to the newly supplied toner. It has a variety of distinctive structures that allow it to be implemented.

First, the first feature is that the stirring roller 8 is used to scrape off the developer on the sleeve 6 and stir the developer. When scraping, do not scrape off all the developer on the sleeve 6.
As in the positional relationship between the sleeve 6 and the stirring roller 8 shown in FIG. 1, the position is such that a slight gap remains between the tip of the stirring blade 7 and the sleeve 6. The reason for this is that the toner consumed during development is mainly on the surface layer of the magnetic brush, so it is only necessary to scrape off within the range that includes the surface layer.Moreover, in this configuration, the rotational torque of the stirring roller 8 is also small, ensuring smooth rotation. This is because it can be done. Furthermore, the tip of the stirring blade 7 is bent in the direction of rotation to form the sleeve 6.
The effect of scraping off the upper developer is enhanced. Referring to FIG. 2, since this stirring roller 8 also serves to transport the developer to the developer pumping position 16 on the sleeve 6, the adjacent stirring blades 7 form a developer transporting space 20. . Moreover, each stirring blade 7 is provided with a plurality of notches 21, and one end of each of the notches 21 is bent so as to be oriented in a certain direction to form a guide 22 to form a developer conveying space. In addition to enabling the movement of the developer between 20 days,
The guides 22 of adjacent stirring blades 7 are shifted at regular intervals in the longitudinal direction, so that a spiral passage 2 is formed on the stirring roller.
By providing 0', the developer transport space 20 can also be moved in the direction of arrow 23. In this way, as the stirring roller 8 rotates in the direction of arrow 17, the developer is stirred and moved in the longitudinal direction of the rotating shaft.

The agitated developer is again supplied onto the sleeve at the pumping position 16.

A second feature of the present invention is that as the developer supplied onto the sleeve is moved by the rotation of the sleeve 6, the developer flow guide mechanism 9 moves the developer in the opposite direction to the stirring roller 8. There is a particular thing. As shown in FIG. 2, the developer guide mechanisms 9 are provided at predetermined intervals on both the upper and lower surfaces of a bent partition plate 25, and are oriented in a direction forming an acute angle or an obtuse angle with the axial direction of the stirring roller. It is composed of a large number of guide plates 26, 26'. The developer conveyed by the stirring roller 8 and pumped up onto the sleeve moves under the partition plate, and is regulated to a certain amount by the cutting plate 12 to form a magnetic brush 13, which is regulated by the cutting plate 12. The remaining developer is pushed up by the surface of the cutting plate 12 on the guide mechanism 9 side, reaches the upper surface of the partition plate 25 provided in the shape of a slope of the guide mechanism 9, and moves along this slope along the guide plate 26. It falls onto the stirring roller 8 again. This partition plate 25
Guide plates 26, 2 attached to the upper and lower surfaces of
6' are attached approximately parallel to each other on each surface,
The upper and lower surfaces are in a positional relationship such that the orientation directions of the guide plates 26, 26' intersect with each other.
In this way, the developer is transported as a whole in the direction of the arrow 27 along the guide plates 26, 26' provided on both the upper and lower surfaces of the partition plate 25.

In the specific example shown in FIGS. 1 and 2, the guide 22 of the notch 21 and the guide plate 2 of the guide mechanism 9
6 and 26' are combined as shown in FIG. It is also possible to carry out a combination in which conveyance or transfer is carried out in the opposite direction. In this case, the bent part of the guide 22 of the notch 21 which is on the right side in FIG. The clockwise direction from the lower left side of FIG. 2 is the counterclockwise direction. Further, the orientation directions of the guide plates 26, 26' of the guide mechanism 9 are set to be opposite in the upper and lower directions, respectively. By changing and combining the notch and the guide plate in this way, conveyance or transfer in the opposite direction becomes possible.

As explained above, according to the present invention, due to the characteristic shape and structure of the stirring roller and the guide mechanism, it is possible to form a developer flow that can perform regular left-right stirring with a compact structure, and to create a developer flow that can perform halftone A forward developing device is provided which is capable of reproducing images and developing with excellent image quality.

[Brief explanation of the drawing]

FIG. 1 is a schematic sectional view showing the developing device of the present invention, and FIG. 2 is a perspective view showing the stirring roller and guide mechanism of the developing device of the present invention. Reference numbers in the figure are 6...sleeve, 7...stirring blade, 8...stirring roller, 9...developer flow guide mechanism, 20...developer transport space, 20'...spiral passage, 21... ...Notch, 22...Guide, 26,2
6'... Indicates a guide board.

Claims (1)

[Scope of Claim for Utility Model Registration] A hopper equipped with a toner supply roller, a developer conveyance sleeve that rotates in the opposite direction to the rotation direction of the photoreceptor drum and has a magnet inside, and a developer conveyance sleeve that rotates in the same direction as the developer conveyance sleeve. an agitation roller that rotates and has a large number of agitation blades for triboelectrically charging the toner particles and uniformly mixing the toner and the carrier; regulating the length of the magnetic brush formed on the developer conveying sleeve; In the two-component developing device, the stirring blade has a bent tip and is oriented in the direction of rotation of the stirring roller. Each of the stirring blades is provided with a notch, and a guide is provided at one end of the notch, and a spiral passage is formed on the stirring roller by the notch and the guide. The developer flow guide mechanism includes a partition plate and a large number of guide plates provided above and below the partition plate at predetermined intervals, and these guide plates form an acute angle or an obtuse angle with the axial direction of the stirring roller. direction, and the guide plates (first guide plate) provided above the partition plate and the guide plates (second guide plate) provided below the partition plate are approximately parallel to each other. A two-component developing device characterized in that the first guide plate and the second guide plate are provided in a positional relationship such that the orientation directions of the first guide plate and the second guide plate intersect with each other.