JPS6356994B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic latent image developing device using magnetic toner.

Conventionally, as a developing device using magnetic toner, a magnet roll is fixed as described in Japanese Patent Publication No. 54-33534, Japanese Patent Application Laid-Open No. 52-17831, or Japanese Patent Application Laid-Open No. 52-67336, etc. Then, the non-magnetic sleeve is rotated and magnetic toner is supplied from the bottom of the hopper-shaped developer tank onto the sleeve, or the non-magnetic sleeve is fixed and a magnet roll is rotated to supply magnetic toner from the bottom of the hopper-shaped developer tank. It has been proposed to visualize an electrostatic latent image formed on the surface of a photoreceptor using a magnetic brush formed by supplying toner onto the sleeve. These developing devices have conventionally functioned well in CPC copiers, facsimile machines, etc., but they do not fully function in electrophotographic devices that require a transfer process, such as PPC copiers. Ta. The reason for this is that in the case of electrophotographic devices that require a transfer process, the fluidity of magnetic toner is lower than that described above because the resistance of magnetic toner is much higher and the particle size distribution tends to be smaller.
It was worse than those used in CPC copying machines, and was prone to agglomeration, forming bridges in the hopper, and clogging between the doctor blade and sleeve. Also,
In a device in which the sleeve is fixed and the magnet roll is rotated, a toner pool tends to grow between the photoreceptor and the sleeve, and toner agglomeration tends to occur in this area. These conditions pose a major problem in visualizing the electrostatic latent image on the surface of the photoreceptor.

An object of the present invention is to provide a developing device that can eliminate the above-mentioned drawbacks of the developing device and always perform good development even when using magnetic toner with a certain degree of fluidity. It is particularly effective in carrying out the developing method previously proposed by et al.

The developing device of the present invention includes a non-magnetic cylindrical sleeve rotatably disposed facing the surface of a material layer holding an electrostatic latent image, and a non-magnetic cylindrical sleeve rotatably disposed inside the non-magnetic cylindrical sleeve. a magnet having a plurality of magnetic poles; and a toner tank disposed adjacent to the non-magnetic cylindrical sleeve and containing magnetic toner; The magnetic toner is supplied from the toner tank onto the non-magnetic cylindrical sleeve, and the ratio of the number of rotations of the magnet to the number of rotations of the non-magnetic cylindrical sleeve is approximately 20 or more. By rotating the cylindrical sleeve and the magnet in the same direction, a constant amount of magnetic toner is generated from near the opposing gap between the surface of the material layer and the non-magnetic cylindrical sleeve along the direction of rotation of the non-magnetic cylindrical sleeve. In a developing device in which a thick layer is formed, a non-magnetic plate having a plurality of openings formed in the longitudinal direction at predetermined intervals is installed approximately tangentially to the non-magnetic cylindrical sleeve, and the tip of the non-magnetic plate is in contact with the surface of the non-magnetic cylindrical sleeve and the opening is set within a distance from the surface of the non-magnetic cylindrical sleeve to the thickness of a constant layer of the magnetic toner, and the opening is located within the toner reservoir. A member is rotatably provided to scrape off magnetic toner overflowing to the toner tank side of the non-magnetic plate and supply magnetic toner in the toner tank onto the non-magnetic sleeve through the opening. That is.

The present invention will be explained in detail below with reference to the drawings. 1st
The figure shows one embodiment of the invention. The magnet 1 having a plurality of magnetic poles and the sleeve 2 containing the magnet 1 rotate together in the direction of the arrow x shown in the figure, and the ratio of their respective rotational speeds is set to approximately 20 or more. At this time, the magnetic toner 4 that has passed between the photoconductor 3 and the non-magnetic cylindrical sleeve 2 moving in the direction of the arrow z shown in the figure
The magnetic toner 4 is conveyed in the direction of the arrow y shown in the figure, and is conveyed from one end of the non-magnetic plate 5 onto the non-magnetic plate 5 to the opening 6 by the rotating magnetic field of the magnet 1, and most of the magnetic toner 4 returns to the non-magnetic cylindrical sleeve 2 as shown in the figure. It is transported in the direction of the arrow y. Magnetic toner that cannot pass between the photoreceptor 3 and the non-magnetic cylindrical sleeve 2 is disclosed in Japanese Patent Application Laid-Open No. 1986-
As shown in Japanese Patent No. 116233, a layer 7 of a constant thickness is coated on a non-magnetic cylindrical sleeve 2.
and the photoreceptor 3 in the direction of the arrow x shown in the figure. The layer 7 of a certain thickness of the magnetic toner is formed when the ratio of the rotational speed of the magnet 1 and the non-magnetic cylindrical sleeve 2 is approximately 20 or more, and its thickness depends on the ratio of the rotational speed or the magnetic force of the magnetic toner. etc., it becomes unique. A layer 7 of constant thickness of such magnetic toner
When the photoconductor 3 is in contact with the photoconductor 3, the contact area is always approximately constant, and a stable developing state can always be maintained. The toner tank 8 is a non-magnetic cylindrical sleeve 2
The magnetic toner 9 is placed adjacent to the magnetic toner 9 .
Further, an arm 11 is installed in the toner tank 8 and has one end supported by a shaft 10 that is substantially parallel to the non-magnetic cylindrical sleeve 2 and that performs a predetermined rotational movement.
At the other end, the magnetic toner 9 in the toner tank 8 is conveyed onto the non-magnetic cylindrical sleeve 2, and the magnetic toner (not shown in FIG. 1) overflowing onto the toner tank side of the non-magnetic plate 5 is scraped off. A member 12 made of a non-magnetic material is attached. In this embodiment, the rotation direction of the member 12 is set in the direction of the arrow w shown in the figure.

The functions of the non-magnetic plate 5 and the member 12 will be further explained in detail below. FIG. 2 is an enlarged view of a portion of FIG. 1, and shows a state in which one end of the constant pressure layer of magnetic toner does not reach the opening 6 of the non-magnetic plate 5. In this state, no magnetic toner overflows to the toner tank 8 side of the non-magnetic plate 5, and only a portion of the magnetic toner 4 moving in the direction of the arrow y on the non-magnetic cylindrical sleeve 2 moves automatically. It's just that. Therefore, the scraped-off portion 12a of the member 12
By moving in the direction of the arrow w in the figure, almost no magnetic toner is scraped off. Also, member 1
The magnetic toner 9 conveying portion 12b of No. 2 has a magnetic toner 9a, and as the member 12 moves within the magnetic absorption force of the magnet 1, the magnetic toner 9a is supplied through the opening 6 onto the non-magnetic cylindrical sleeve. Ru. Therefore, the layer 7 of a constant thickness of magnetic toner gradually grows in the direction of the arrow x shown in the figure and reaches the position of the opening 6. FIG. 3 shows a state in which a layer 7 of a constant thickness of magnetic toner has reached the opening 6. As shown in FIG. When the layer 7 of a certain thickness of magnetic toner reaches the opening 6, it overflows from the opening end 5a of the non-magnetic plate 5 to the wall surface on the side of the toner tank 8 due to the rotating magnetic field of the magnet 1, forming a magnetic toner pool 7a. . A portion of the magnetic toner forming the magnetic toner pool 7 is scraped into the toner tank 8 by the scraping portion 12a of the member 12 rotating in the direction of the arrow w in the figure. Further, even in such a state, the magnetic toner conveying section 12 of the member 12
There is magnetic toner 9a in b, which is conveyed onto the non-magnetic cylindrical sleeve 2, but the amount of conveyed toner is greater than the amount scraped off by the scraping portion 12a of the member 12 when the magnetic toner reservoir 7a reaches a saturated state. Less is better. Further, the relationship between the thickness f of the layer 7 of a constant thickness of magnetic toner and the distance d between the end 5a of the opening 6 of the non-magnetic plate 5 and the non-magnetic cylindrical sleeve 2 must be such that f>d. It is. It goes without saying that the amount of magnetic toner flowing out from the opening 6 onto the non-magnetic cylindrical sleeve 2 should be set to be sufficient to form a layer 7 of a constant thickness of magnetic toner. Moreover, the setting has a much wider tolerance range and is more stable than the conventionally widely used method using a magnetic toner flow rate regulating plate. In addition, since a part of the non-magnetic plate 5 is in contact with the surface of the non-magnetic cylindrical sleeve 2, the surface of the non-magnetic cylindrical sleeve 2 is constantly cleaned and no toner particles or the like can adhere thereto.

FIG. 4 shows an example of the non-magnetic plate 5 in the above embodiment. The material of the non-magnetic plate 5 may be Mylar, plastic, or phosphor bronze, but the material is not a factor as long as the above-mentioned functions are satisfied. FIG. 5 shows another shape of the non-magnetic plate 5, in which the end portion 5
b has an arcuate shape so as to be in surface contact with the surface of the non-magnetic cylindrical sleeve 2. End portions 5c of these non-magnetic plates 5 that come into contact with the non-magnetic cylindrical sleeve 2
It is desirable that the magnetic toner 4 is thin enough to prevent movement of the magnetic toner 4 by the rotating magnetic field of the magnet 1. Further, the shape of the opening 6 may be circular or triangular, or may be irregular in size, etc., as long as it satisfies the above-mentioned function.

The embodiment described above is an example of the present invention, and the position of the non-magnetic plate 5 or the toner tank 8 is arbitrary within the possible range. Further, the shape of the member 12 is not limited to the shape described in this embodiment, and the scraping portion 12a and the conveying portion 12b may be separated, or may have a plurality of pieces.

As described above, even when using magnetic toner with poor fluidity, the developing device according to the present invention can
It can always perform stable phenomena and is particularly suitable for electrophotographic devices that require a transfer process.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the developing device of the present invention, FIGS. 2 and 3 are enlarged views of the main parts of FIG. 1 for explaining the present invention, and FIGS. 4 and 5 are FIG. 3 is a diagram showing an example of a non-magnetic plate used in this embodiment. 1: Magnet, 2: Sleeve, 3: Photoreceptor, 4: Magnetic toner, 5: Non-magnetic plate, 6: Opening of non-magnetic plate 5, 7a: Magnetic toner reservoir, 8: Toner tank, 12:
Toner scraping and supply member.

Claims (1)

[Claims] 1 a non-magnetic cylindrical sleeve rotatably disposed opposite the surface of the material layer holding an electrostatic latent image;
a magnet having a plurality of magnetic poles rotatably disposed inside the non-magnetic cylindrical sleeve; and a toner tank disposed adjacent to the non-magnetic cylindrical sleeve for containing magnetic toner; An amount of magnetic toner greater than the amount that can pass between the surface of the layer and the non-magnetic cylindrical sleeve is supplied from the toner reservoir to the non-magnetic cylindrical sleeve, and the number of rotations of the magnet and the non-magnetic cylindrical sleeve are By rotating the non-magnetic cylindrical sleeve and the magnet in the same direction so that the ratio of the rotational speed of In a developing device in which a layer of magnetic toner is formed with a constant thickness along the rotational direction of the non-magnetic cylindrical sleeve, a non-magnetic plate having a plurality of openings formed in the longitudinal direction at predetermined intervals is attached to the non-magnetic cylinder. The distal end of the non-magnetic plate is in contact with the surface of the non-magnetic cylindrical sleeve, and the opening extends from the surface of the non-magnetic cylindrical sleeve to a certain thickness of the magnetic toner. set within a distance up to the thickness of the toner layer, scrape off the magnetic toner overflowing to the toner tank side of the non-magnetic plate into the toner tank, and transfer the magnetic toner in the toner tank to the non-magnetic layer through the opening. A developing device characterized in that a feeding member is rotatably provided on a cylindrical sleeve.