JPH03102374A - Developing device - Google Patents

Abstract

PURPOSE:To always maintain carriers in the vicinity of a developer carrying roll, to keep toner concentration and the volume of the carriers on the developer carrying roll constant and to perform stable, high-quality image recording by providing a magnet inside a storing vessel in the vicinity of a magnetic developer port thereof. CONSTITUTION:A plate-like permanent magnet 10 is provided on the inner wall surface in the vicinity of the developer port 2a of the storing vessel 2, and the magnetism of the permanent magnet 10 maintains the magnetic carriers 4 between the permanent magnet 10 and the developer carrying roll 1. A part of the magnetic carriers 4 is carried on a sleeve 1a by the magnetism of the magnet 1b of the developer carrying roll 1, and moves together with the rotation of the sleeve 1a. The magnetic carriers that are not carried on the sleeve 1a do not flow, but are maintained between the sleeve 1a and the permanent magnet 10 as they are. Consequently, the volume of the magnetic carriers carried on the sleeve 1a is always constant, whereby the concentration of toner on the sleeve 1a is kept constant to prevent the variance of image density.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a developing device that is used in an electrophotographic recording device such as a laser beam printer and executes a developing process during an electrophotographic process. .

(Prior Art) As one of the developing methods in the development process of electrophotographic recording, magnetic carrier is stored around a developer carrier roll in a storage container that stores magnetic developer and magnetic carrier. There is a method of mixing a magnetic developer and a magnetic carrier near a developer carrier roll.

FIG. 2 is a sectional view showing an example of the configuration of a conventional developing device that performs development using such a developing method. In the figure, reference numeral 1 denotes a developer carrier roll, which is provided in parallel to a photoreceptor drum (not shown).

This developer carrier roll 1 consists of a cylindrical sleeve 1a made of a non-magnetic material and a magnet body 1b provided inside the sleeve 1a.
rotates in the direction of arrow A, and the magnet body 1b rotates in the direction of arrow B, respectively. The developer carrier roll 1 is located at the opening of the storage container 2 with a portion thereof being located inside the storage container 2.

The storage container 2 contains a magnetic developer (hereinafter referred to as toner).
3 and a magnetic carrier (hereinafter referred to as carrier) 4 are stored. Reference numeral 5 denotes a blade provided at the toner outlet 2a of the storage container 2, and when the developer carrier roll 1 is rotated, the toner 3 carried by the developer carrier roll 1 is guided to the outside of the storage container 2. and the amount of carrier 4 is kept constant. Note that 6 is a developer transport mechanism for supplying the toner 3 to the developer carrier roll 1.

In such a developing device, in the initial state, the carrier 4 is attached to the developer carrier roll 1 as shown by the broken line in the figure.
is located near. In addition, the developer carrier roll 1
It is also attached to the surrounding area.

Then, the toner 3 is mixed into the carrier 4 little by little and carried on the developer carrying roll 1.

However, with such a structure, the rotation of the sleeve 1a causes the carriers 4 to move as shown by arrow C in FIG. 2, and gradually disperse over the entire area of the storage container 2.

If the carrier 4 is dispersed in this way, the mixing ratio (toner concentration) of the toner 3 and the carrier 4 carried on the developer carrier roll 1 will change, resulting in variations in recorded images.

In addition, the carrier 4 also has a cleaning effect on the sleeve la, but by dispersing the carrier 4, the sleeve l
There is a risk that the cleaning action on the sleeve a will be insufficient, and blocking toner will be formed on the sleeve la, leading to deterioration in the quality of the recorded image.

(Problems to be Solved by the Invention) As described above, in the conventional developing device, the carrier is simply disposed near the developer carrier roll, so the carrier is dispersed by rotation of the developer carrier roll 1, etc. This causes problems in that the toner density changes and blocking toner is left on the developer carrier roll, causing density variations and deterioration of image quality in recorded images.

The present invention has been made in consideration of these circumstances, and its purpose is to maintain the carrier near the developer carrier roll at all times to improve the toner concentration and the developer carrier roll. Keeping the amount of carrier constant,
An object of the present invention is to provide a developing device that enables stable recording of high-quality images.

[Structure of the Invention] (Means for Solving the Problems) In the present invention, a magnet is provided inside the storage container near the magnetic developer outlet of the storage container.

(Function) By taking such measures, the magnetic carrier is held by the magnetic force generated by the magnet provided inside the storage container near the magnetic developer outlet of the storage container, and the magnetic carrier is held by the rotation of the developer carrier roll. The accompanying flow of magnetic carriers does not occur much. Therefore, scattering of the magnetic carrier over the entire area of the storage container is reduced.

(Example) Hereinafter, a developing device according to an example of the present invention will be described with reference to the drawings.

FIG. 1 is a sectional view showing the structure of the developing device.

Note that the same parts as in FIG. 2 are denoted by the same reference numerals, and detailed explanation thereof will be omitted.

Here, the features of this developing device are that, in addition to the conventional developing device shown in FIG.
A plate-shaped permanent magnet 10 is provided on the inner wall surface near point a, and the carrier 4 is stored between this permanent magnet and the developer carrier roll 1. In addition, in the same figure, 11 is a permanent magnet 10.
This is a fixing member for fixing.

The magnetic force of the permanent magnet 10 is smaller than the magnetic force of the magnet body 1b of the developing carrier roll 1. Further, the upper part of the fixing member l1 is an inclined surface, and the angle of inclination of this inclined surface is set to such an angle that the toner 3 easily falls.

According to the present developing device configured as described above, the magnetic carrier 4 is held by the magnetic force of the permanent magnet 10, and a part of the magnetic carrier 4 is held by the sleeve 1a by the magnetic force of the magnet body 1b of the developer carrier roll. and moves as the sleeve rotates.

Therefore, the magnetic carriers not supported by the sleeve 1a do not flow and are held between the sleeve 1a and the permanent magnet 10 in the same state as the initial state. This results in
Since the amount of magnetic carrier supported on the sleeve 1a is always constant, the toner density on the sleeve]a can be kept constant, and variations in image density can be prevented. Furthermore, since the amount of carrier 4 around the developer carrier roll 1 is hardly reduced, the cleaning effect does not deteriorate, and it is possible to prevent the generation of blocking toner and deterioration of image quality.

In addition, in order to perform good recording, the magnetic force of the permanent magnet 10, the distance between the permanent magnet and the sleeve 1a, the amount of the magnetic carrier 4, etc. are adjusted, and the toner concentration on the sleeve 1a is adjusted to 2.
It is desirable to set it to about 0 to 90% (more preferably 40 to 70%).

As described above, according to this embodiment, scattering of the carrier 4 can be suppressed to keep the toner concentration substantially constant, and development can always be performed in an optimal state.

Furthermore, according to this embodiment, the amount of magnetic carrier 4 supported on the sleeve 1a can be changed by changing the magnetic force of the permanent magnet 10, and the toner concentration can be adjusted by replacing the permanent magnet 10. can.

Note that the present invention is not limited to the above embodiments. For example, in the embodiment described above, the permanent magnet 10 is provided so as to protrude perpendicularly from the side wall of the storage container 2, but it is also possible to provide it in a state where it is embedded in the side wall of the storage container 2, for example.

Furthermore, although permanent magnets are used as magnets in the above embodiments, electromagnets may also be used. Furthermore, when an electromagnet is used as the magnet, changes in recording characteristics due to changes in the above conditions are corrected by changing the magnetic force and toner concentration according to various conditions that affect recording characteristics, such as ambient temperature. You can also. In addition, various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] According to the present invention, since the magnet is provided inside the storage container near the magnetic developer outlet of the storage container, the carrier can always be held near the developer carrier roll. This makes it possible to keep the toner concentration and the amount of carrier on the developer carrier roll constant, and to stably record high-quality images.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing the configuration of a developing device according to an embodiment of the present invention, and FIG. 2 is a sectional view showing an example of the configuration of a conventional developing device. 1...Developer carrier roll, 1a...Sleeve, 1
b... Magnet, 2... Storage container, 2a... Toner outlet, 3... Magnetic developer (toner), 4... Magnetic carrier (carrier), 5... Blade, 10... ...Permanent magnet, 11...Fixing member. Figure 1

Claims (1)

[Scope of Claims] A storage container for storing a magnetic developer and a magnetic carrier, a part of which is located inside the storage container, and a storage container for storing the magnetic developer and magnetic carrier stored in the storage container. A developing device comprising a developer carrier roll that carries the magnetic developer and magnetic carrier by magnetic force and rotates to convey the magnetic developer and the magnetic carrier, wherein a magnet is provided inside the storage container near the magnetic developer outlet of the storage container. A developing device characterized by being provided with.