JPH0429063B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a developing device used in an electrophotographic recording device.

(Prior Art) In the prior art, a fixed magnetic field generating means is arranged inside a moving toner supporting means, and a magnetic member for regulating the layer thickness of magnetic toner is placed outside the toner supporting means, that is, on the opposite side of the magnetic field generating means. are arranged, and constitute a stationary magnetic field with the toner supporting means sandwiched between the fixed magnetic field generating means and the magnetic member,
For example, there is Special Publication No. 59-8831. In this configuration, the magnetic toner that tends to remain in the static magnetic field is pulled out by the movement of the toner support means, and a thin layer of magnetic toner is formed on the surface of the toner support means.

(Problems to be Solved by the Invention) In the prior art as described above, the stationary magnetic field formed by the fixed magnetic field generating means and the magnetic member is strong, and the magnetic toner is generated by the movement of the toner supporting means. Although the magnetic toner is easily transported up to the stationary magnetic field, only a small amount of the magnetic toner is pulled out from there because the force that tries to stop it in the stationary magnetic field is strong. Therefore, although it is effective in forming a thin layer of magnetic toner, the amount of magnetic toner that remains in the static magnetic field increases, resulting in toner agglomeration. If the magnetic toner is drawn out in this state, the density of the drawn magnetic toner becomes unstable, causing a problem in that the density of printed characters becomes uneven.

SUMMARY OF THE INVENTION An object of the present invention is to prevent agglomeration of magnetic developer from occurring and to form a stable, uniform, and thin developer layer on a developer-carrying surface.

(Means for Solving the Problems) The present invention is characterized by a developer carrying member that moves while supporting a magnetic developer on its surface, and a predetermined position on the opposite side of the developer carrying surface of the developer carrying member. A magnetic field generating means that reciprocates with a displacement width, and a magnetic body disposed on the developer carrying surface side at a constant distance from the developer carrying surface within the range of the magnetic field generated by the magnetic field generating means. A developer layer thickness regulating member is provided.

(Function) As the magnetic field generating means reciprocates, the strength of the magnetic field formed between the magnetic field generating means and the developer layer thickness regulating member changes, and the magnetic field near the developer layer thickness regulating member changes. The magnetic developer being transported smoothly forms a thin layer on the developer carrying surface without agglomerating.

(Example) An embodiment of the present invention will be described based on the drawings.

In FIG. 1, a cylindrical developer carrier 3 is rotatably housed in a container 2 for magnetic developer 1, and the magnetic developer 1 is contained in a developer carrier surface 3a on the surface of the developer carrier 3. is supported by the container 2 due to its rotation.
will be removed from. A cylindrical magnet is built in the developer carrier 3 as a magnetic field generating means 4. The magnet 4 has a large number of magnetic poles on the circumferential surface.
S is alternately magnetized. Magnetic developer 1 from container 2
A developer layer thickness regulating member 5 made of a magnetic material is attached at a certain distance from the developer carrying surface 3a at the outlet where the developer is carried out. The developer layer thickness regulating member 5 is located within the range of the magnetic field generated by the magnetic pole of the magnet 4.

A magnet 4, which is a magnetic field generating means, is set to reciprocate with a predetermined displacement width.
Now, when a magnet with a diameter of 27 mm is reciprocated within a center angle θ=18°, it reciprocates on its outer peripheral surface in a direction parallel to the moving direction of the developer carrier 3 with a displacement width d1=4.4 mm. At the same time, the developer carrier 2 was set to rotate clockwise to transport the magnetic developer 1.

The magnetic developer 1 that has been conveyed to the exit on the carrying surface 3a of the developer carrier 3 tries to stop there due to the magnetic field formed between the developer layer thickness regulating member 5 and the magnet 4. However, since the strength of this magnetic field fluctuates due to the vibration of the magnet 4, it does not agglomerate, and subsequently, as the developer carrier 3 rotates, the developer passes through the developer layer thickness regulating member 5 and forms a predetermined layer. The photoreceptor is supported on the support surface 3a with a stable, uniform, and thin layer thickness, and is conveyed to a transfer position facing the photoreceptor drum 6.

The second illustration shows an example in which the magnet 14 is formed into a rod shape, and magnetic poles N and S are formed on the upper and lower sides thereof. A developer layer thickness regulating member 15 is disposed within the range of the magnetic field generated by the upper magnetic pole N.
The magnet 14 has a predetermined displacement width d in the direction perpendicular to the moving direction of the developer carrier 13, that is, in the vertical direction.
2, so that the strength of the magnetic field formed between the magnet 14 and the developer layer thickness regulating member 15 fluctuates to prevent agglomeration of the magnetic developer material 1. It is something to do. The other structure is the same as the example shown in the first figure.

(Effects of the Invention) As described above, the present invention reciprocates the magnetic field generating means with a predetermined displacement width, so that the strength of the magnetic field formed between the magnetic field generating means and the developer layer thickness regulating member is reduced. It is possible to always form a stable and uniform thin developer layer on the developer carrying surface without causing any fluctuation or agglomeration of the magnetic developer.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a main part of a first embodiment of the present invention,
FIG. 2 is a sectional view of a main part of the second embodiment. 1... Magnetic developer, 3, 13... Developer carrying member, 3a... Developer carrying surface, 4, 14... Magnetic field generating means (magnet), 5, 15... Developer layer thickness regulating member, d1 , d2...displacement width.

Claims (1)

[Scope of Claims] 1. A developer carrier that moves while supporting a magnetic developer on its surface, and a magnetic field that moves back and forth with a predetermined displacement width on the opposite side of the developer carrying surface of the developer carrier. a developer layer thickness regulating member made of a magnetic material and disposed on the developer carrying surface side at a constant distance from the developer carrying surface within the range of the magnetic field generated by the magnetic field generating means; A developing device comprising: 2. The developing device according to claim 1, wherein the magnetic field generating means reciprocates in a direction parallel to the moving direction of the developer carrier. 3. The developing device according to claim 1, wherein the magnetic field generating means reciprocates in a direction perpendicular to the moving direction of the developer carrier.