JPH0254291A - developing device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention generally relates to a developing device, and more particularly to a developing device used in an image forming apparatus such as an electrophotographic copying machine or a laser beam printer.

As is well known, this type of developing device includes a toner hopper having an opening set close to an image carrier, and a developing sleeve rotatably supported by the opening of the toner hopper. The developer accommodated in the toner hopper is held by the developing sleeve, and the developer is supplied to the image carrier by a developing bias voltage applied to the developing sleeve. In recent years, as the demand for color image forming apparatuses that visualize the electrostatic Ns image being formed has rapidly increased, the size of these apparatuses has increased. As efforts have been made to reduce costs, small, low-cost monochrome image forming apparatuses have been commercialized. As monochrome image forming apparatuses are becoming smaller, cheaper, and more compact, it is necessary to install multiple developing devices with the above-mentioned configuration in the limited space around the image carrier. It is absolutely necessary to downsize each developing device to be arranged. Therefore, the storage capacity of the developer in the toner hopper in the developing device becomes small, so a developer storage capacity is required separately from the toner hopper provided in each developing device.
Image forming apparatuses have been developed in which seven stages are provided corresponding to individual developing devices.

However, the supply of developer from the hopper described in - to the toner hopper of each developing device is uniformly carried out over the entire area in the rotation axis direction of the developing sleeve accommodated in the toner hopper. The ideal is. Therefore, each of the hoppers is usually arranged in an upper area of each of the developing devices in the image forming apparatus. However, in an image forming apparatus in which there is not enough space in the upper area of each developing device to arrange each of the hoppers, each of the developing devices has a structure in which the longitudinal direction is longer than the length in the rotational axis direction of the image carrier. A developing device is used, which has a hopper section at its longitudinal end, and is provided with a developer conveying screw that conveys the developer from the hopper section to the toner hopper. When the remaining amount of developer contained in the toner hopper decreases, the developer is supplied to the toner hopper from the aforementioned hopper section.

However, in the developing device described above, which has a shape in which the longitudinal direction is longer than the length in the rotational axis direction of the image carrier, and in which the longitudinal end portion is a hopper portion,
If the rotation speed of the developer conveying screw is slow, it will take too long to supply the developer from the hopper to the developing sleeve, and if the developer cannot keep up, the static electricity formed on the image carrier will increase. There is a possibility that the latent image cannot be developed. on the other hand,
In order to reliably visualize the electrostatic latent image formed on the image carrier, by increasing the rotation speed of the developer conveying screw, a large amount of developer is supplied to the developing sleeve in a short time.
There is a problem in that oversupplied developer aggregates within the toner hopper, which causes a problem in that the image quality of the visualized image deteriorates.

Therefore, the present invention was devised to solve the above-mentioned problems, and its purpose is to prevent the electrostatic latent image on the blue carrier from becoming visible. Even if the amount of developer replenishment is significantly increased to eliminate replenishment delays, this will prevent the developer from agglomerating and will always provide an approximately constant amount of developer to the developing sleeve balls, resulting in stable, high-quality visible images. An object of the present invention is to provide a developing device capable of obtaining an image.

The above objects are achieved by a developing device according to the present invention. To summarize, the present invention provides a developer container that is provided in a region close to an image carrier, has an opening formed in a region facing the image carrier, and accommodates a magnetic developer; The developer holding and carrying out means is rotatably supported by the opening of the developer container, and the developer holding and carrying out means is held by the developer holding and carrying out means 1n, and the magnetism is applied to the developer holding and carrying out means by magnetic force. 1i'i? magnetic field generating means for attracting and holding the developer to the developer holding and transporting means; and 1i'i?
A developer conveying means provided in the developer container and configured to receive the supplied magnetic developer and convey it to the developer holding and conveying means; and a developer holding amount adjustment mechanism that adjusts the amount of magnetic developer held on the developer holding and discharging means by adjusting the action of the magnetic force from the magnetic field generating means on the supplied magnetic developer. This is a developing device characterized by having:

1. Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

As already mentioned, the developing device according to the present invention is used to convert an electrostatic latent image formed by an image forming apparatus such as an electrophotographic copying device or a laser beam printer into a visible image. As is clear with reference to FIG. 1 showing a first embodiment of the present invention, the developing device is a longitudinal type which is disposed close to an image carrier, that is, a photosensitive drum 4 in one image forming apparatus. It has a housing whose length in the direction is longer than the length in the rotation axis direction of the photoreceptor drum 4. In FIG. 1, a magnetic developer 2, such as a one-component magnetic toner having a high electrical resistance value, is stored in a toner hopper 8, and a magnetic developer 2, such as a one-component magnetic toner having a high electric resistance value, is stored in the toner hopper 8. An opening 8a is formed in a portion facing the outer peripheral surface of the body drum 4. A developer holding/exporting means, that is, a developing sleeve 1 is exposed to the opening 8a, and a magnetic blade 3 whose one end side is fixed to the opening 8a is operable in contact with the outer peripheral surface of the developing sleeve 1. is provided. A developing bias power source (not shown) is connected to the developing sleeve l. On the other hand, the opening 8a of the toner hopper 8 faces the developing sleeve l.
The main body part 8b of the toner hopper 8 is formed to have a substantially U-shaped cross section, and the main body part 8b of the toner hopper 8 has a partition part 9 formed integrally with the main body part 8b. A developer transporting means, that is, a developer return screw 6 and a developer transport screw 5, whose rotational speed can be freely adjusted and whose developer transport amount can be freely varied by adjusting the rotational speed, are respectively disposed through the developer transporting means. There is. Note that a developer residual sulfur detection means (not shown) such as a piezo element is provided inside the main body 8b of the toner hopper 8 toward the surface in FIG. The magnetic developer 2 is replenished from the hopper section, which will be described later, to the main body section 8b of the toner hopper 8 based on the detection signal from the toner hopper 8.

The above configuration will be further explained as follows. That is, the developing sleeve l is made of a non-magnetic metal material such as stainless steel or aluminum, and is rotatably supported by the toner hopper 8 in the direction of the surface in FIG. That is, a magnet lO having a substantially cylindrical shape is fixedly interposed. The magnet 10 attracts and holds the magnetic developer 2, which has been conveyed toward the developing sleeve 1 by the developer feeding screw 5 and the developer returning screw 6, toward the developing sleeve 1 by magnetic force. 4 of sz
It has magnetic poles. The developing sleeve 1 uses the magnetic force of the developer pumping pole sZ of the magnet 10 to transfer the magnetic developer 2 that has been moved toward the developing sleeve 1 in the toner hopper 8 by the developer feed screw 5 and the developer return screw 6. The magnetic developer 2 is drawn and held by the toner hopper 8, and the drawn and held magnetic developer 2 is carried out to the outside of the toner hopper 8 by one rotation. The magnetic blade 3 is
The layer of magnetic developer 2 held on the developing sleeve 1 is formed into a uniform thin layer by the magnetic force of the magnet 10. The developer feeding screw 5 feeds the toner hopper 8 from a hopper portion (not shown) attached to an end of the toner hopper 8 main body portion 8b extending toward the surface direction in FIG.
After receiving the magnetic developer 2 replenished into the main body part 8b, the first
The developer return screw 6 receives the magnetic developer 2 transported toward the surface in FIG. 1 by the developer feed screw 5 and transports it toward the surface in FIG. 1. It is composed of

According to the first embodiment of Kibatsu II+, there is a gap between the opening 8a of the toner hopper 8 and the main body 8b of the toner hopper 8.
A developer retention adjustment mechanism, that is, a developer supply restriction member 7 is provided. The developer supply limiting member 7 allows the magnetic developer 2 circulating in the main body 8b of the toner hopper 8 by the developer feed screw 5 and the developer return screw 6 to be developed by the magnetic force from the magnet IO. It is configured to limit the amount of the developing sleeve 1 that is drawn toward the sleeve 1 and held on the developing sleeve 1. That is, the developer supply limiting member 7 is configured to hold the magnetic developer 2 which is held on the developing sleeve l and circulates in the vicinity of the opening 8a in the direction toward the surface of FIG. The screw 6 separates the magnetic developer 2 which circulates within the main body 8b of the toner hopper 8.

In the developing device configured as described above, the magnetic developer 2 is circulated within the main body 8b of the toner hopper 8 by the developer feed screw 5 and the developer return screw 6.
The first magnetic force of the pumping pole sZ of the magnet 10
As shown by arrow C in the figure, it is attracted and held by the developing sleeve 1, and as the developing sleeve 1 rotates in the direction a in FIG. Ru. The magnetic developer 2, which is formed into a uniform thin layer by the Fa magnetic blade and held on the developing sleeve 1, passes through the magnetic blade 3 while being held on the developing sleeve 1 by the action of the magnetic field generated from the magnet hlo. The outer peripheral surface of the developing sleeve 1 and the photoreceptor drum 4
The electrostatic latent image formed on the photoreceptor drum 4 is visualized by being transported to the development position, which is the closest area to the outer circumferential surface of the photoreceptor drum 4 . On the other hand, the magnetic developer 2 forcibly separated from the developing sleeve 1 by the magnetic blade 3
As described above, while circulating in the vicinity of the opening 8a in the direction of the arrow d in FIG. Move circularly within 8b. By the way, since the magnetic developer 2 held on the developing sleeve 1 is consumed every time the above-mentioned developing process is completed, the magnetic developer 2 that is in short supply is removed by the magnetic force of the pumping pole s2 of the magnet 1°. It becomes necessary to replenish the developing sleeve 1 from within the main body portion 8b. However, since the developer supply limiting member 7 is provided between the opening portion 8a and the main body portion 8b as described above, replenishment of the magnetic developer 2 from the hopper portion (not shown) to the toner hopper 8 is prevented. Even in the case where the magnetic developer 2 is attracted by the magnetic force of the pumping pole S of the magnet 10, the developer supply limiting member 7
Therefore, it is physically restricted to a certain extent.

As is clear from the above, since the developer supply limiting member 7 is provided between the opening 8a of the toner hopper 8 and the main body 8b, the magnetic developer circulating in the main body 8b is It is possible to physically limit the magnetic force of the magnet 10 acting on the developer 2, thereby making it possible to stably maintain the amount of the magnetic developer 2 circulating within the main body 8b. The amount of magnetic developer 2 held on the developing sleeve l by the magnetic force of 10 is always determined regardless of whether a large amount of magnetic developer 2 is replenished from the hopper section (not shown) to the main body 8b of the toner hopper 8. It is also possible to adjust it to a substantially constant value, thereby preventing problems such as the magnetic developer 2 coagulating on the developing sleeve 1.

It should be noted that a more remarkable effect was observed in the magnetic developer 2, especially when a highly cohesive magnetic developer having an average particle size of IOILm or less was used.

FIG. 2 shows a developing device according to a second embodiment of the present invention. In this embodiment, as is clear with reference to FIG. A toner hopper is used in which the distance between the toner hopper 8a and the main body 8b is larger than the toner hopper 8 shown in FIG. . That is, in this embodiment, by enlarging the distance between the developing sleeve l and the developer return screw 6 in the lateral direction (horizontal direction), the magnetic developer 2 moved by the developer return screw 6 is affected. Since the magnetic force of the magnet IO is weakened, the developer supply limiting member 7 provided in the first embodiment
Even without using the magnetic developer 2, it is possible to adjust the amount of the magnetic developer 2 held on the developing sleeve 1 to a substantially constant level by the magnetic force of the magnet IO. In FIG. 2, the same components as those shown in FIG. 1 are designated by the same reference numerals, and their explanation will be omitted.

FIG. 3 shows a developing device according to a third embodiment of the present invention. In this embodiment, as is clear with reference to FIG. A toner hopper is used in which the bottom of the main body 8b is deeper than the bottom of the main body 8a.
It also has a function as a developer retention amount adjustment mechanism. That is, in this embodiment, the developer feeding screw 5 and the developer return screw 6 are connected to the developing sleeve l.
By setting and arranging the magnetic developer 2 at a position lower than that of the developer return screw 6,
Since the magnetic force of the magnet 10 acting on is weakened,
Even without using the developer supply restriction member 7 provided in the first embodiment, it is possible to adjust the amount of magnetic developer 2 held on the developing sleeve 1 to a substantially constant level by the magnetic force of the magnet 10. It is. In FIG. 3, the same parts as those shown in FIG. 1 are designated by the same reference numerals, and the explanation thereof will be omitted.

As explained above, according to the present invention, by adjusting the action of the magnetic force from the magnetic field generating means on the magnetic developer supplied onto the developer holding and discharging means by the developer conveying means. Since the amount of magnetic developer held on the developer holding and transporting means is adjusted, the amount of static 1 ton of developer on the image carrier is adjusted. I? Even if the amount of developer replenishment is significantly increased to eliminate developer replenishment delays in order to prevent images from becoming unvisible, this prevents developer agglomeration and maintains a nearly constant amount of developer at all times. By providing the developer on the developer holding and transporting means, it is possible to provide a developing device that can obtain stable and high-quality visible images.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a developing device according to a first embodiment of the present invention. FIG. 2 is a longitudinal sectional view showing a developing device according to a second embodiment of the present invention. FIG. 3 is a longitudinal sectional view showing a developing device according to a third embodiment of the present invention. 1: Developing sleeve: Magnetic developer: Photosensitive drum: Developer feed screw: Developer return screw: Developer supply regulation member; Toner hopper: Opening: Magnet

Claims (1)

[Claims] 1) A developer container provided in a region close to the image carrier, with an opening formed in a region facing the image carrier, and accommodating a magnetic developer; The developer holding and carrying out means is rotatably supported in the opening and the magnetic developer is held by the developer holding and carrying out means and is applied to the developer holding and carrying out means by magnetic force. a magnetic field generating means for attracting and holding the developer to the carrying-out means; a developer transporting means provided in the developer container for receiving the supplied magnetic developer and transporting it to the developer holding and carrying-out means; The amount of magnetic developer held on the developer holding and carrying out means is controlled by adjusting the effect of the magnetic force from the magnetic field generating means on the magnetic developer supplied to the developer holding and carrying out means by the means. A developing device comprising: a developer holding amount adjusting mechanism.