JPH04355476A - Developing device - Google Patents

Abstract

PURPOSE:To provide a developing device capable of sufficiently charging a developer without having a bad influence on an image at the time of development. CONSTITUTION:A layer thickness regulating member 12 for regulating the layer thickness of a developer supported on the surface of a developing sleeve 8 and carried is extended while curing circularly along the developing sleeve 8 surface to form a carrying passage 14 for the developer with the developing sleeve 8 surface. The dimension (clearance (alpha) of the inlet port 14A of the carrying passage 14 is larger than the dimension (clearance beta) of the discharge port 14B for discharging the developer with layer thickness regulation, and an unevenness 15 for accelerating the frictional charge of the developer is formed on the carrying passage forming surface side of the layer thickness regulating member 12.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device equipped with a developer conveying roller, a developing roller, etc. in an image forming apparatus such as an electronic copying machine.

0002

2. Description of the Related Art Conventionally, for example, a developing device of a high-speed copying machine is constructed as shown in FIG. The two-component developer) is stirred by a paddle roller (not shown), and the developer frictionally charged by this stirring is transported by a conveying roller 2A to developing rollers 4 and 5 arranged in two stages facing the photoreceptor drum 3. The developer is conveyed to the side, and the conveyed developer is rubbed against the photoreceptor drum 3 by the developing rollers 4 and 5, so that toner is attached to the latent image formed on the photoreceptor drum 3 and developed (multi-stage development). It is supposed to be done. The excess developer on the developing roller 5 side is returned to the conveying roller 2A side through a passage above the developing housing 1 by a recovering conveying roller 2B.

The developing rollers 4 and 5 have a structure in which cylindrical developing sleeves 8 and 9 made of a non-magnetic material are rotatably provided on the outside of magnet structures 6 and 7 to which a plurality of permanent magnets are fixed. (The outer conveyance sleeves of the conveyance rollers 2A and 2B are rotatable relative to the internal magnet structures.) The magnetic force from the magnet structures 6 and 7 causes the development to occur on the surfaces of the development sleeves 8 and 9. A magnetic brush is formed by supporting the agent, and this magnetic brush is caused to rub against the photosensitive drum 3 by rotation of the developing sleeves 8 and 9. still,
The magnet components 6 and 7 are press-fitted or adhesively fixed to the magnet roller shafts 10 and 11 fixed to the developer housing 1 side, and the layer thickness of the developer supported on the surface of the developer sleeves 8 and 9 is regulated. It is regulated to be uniform in the axial direction by a member (ear cutting plate) 12. Furthermore, the developer conveyed to the developing roller 4 side is regulated by the regulating end 13A of the partition plate 13 to prevent the developing roller 4 from being immersed in the developer.

0004

[Problems to be Solved by the Invention] In a developing device having such a conventional configuration, in order to compensate for insufficient charging of the developer due to stirring by the paddle roller, grooves are formed on the surface of the developing sleeve to During rotation, these grooves cause the toner and carrier in the developer to be more strongly tribo-electrified, thereby preventing the generation of uncharged toner. However, in this charge reinforcement method, when the circumferential speed ratio (S/D ratio) between the photoreceptor drum and the developing sleeve decreases, the grooves on the surface of the developing sleeve cause unevenness (striped pattern) in the developed image. Therefore, it was unsuitable as a developing device for a high-speed copying machine where the circumferential speed ratio is set low. The present invention has been made in view of the above points, and an object of the present invention is to provide a developing device that can sufficiently charge a developer without adversely affecting an image during development. .

[0005]

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention includes a developing roller which is rotatably provided with a developing sleeve on the outside of a magnet structure fixed to a magnet roller shaft, and a developing sleeve supported on the surface of the developing sleeve. In the developing device, the layer thickness regulating member extends along the surface of the developing sleeve and controls the thickness of the developer between the layer thickness regulating member and the developing sleeve surface. In addition to forming a conveyance passage, the size of the inlet of the conveyance passage is larger than the size of the outlet through which the developer is discharged after regulating the layer thickness, and the conveyance passage forming surface of the layer thickness regulating member is The surface has irregularities formed thereon to promote triboelectric charging of the developer.

[0006]

[Operation] According to this configuration, when the developer carried on the surface of the developing sleeve of the developing roller and transported to the photosensitive drum side passes through the transport path, the carrier and the toner are strongly frictionally charged with each other. At the same time, the layer thickness regulating member is in sliding contact with the uneven conveying path forming surface, and also in sliding contact with the excess developer that flows backwards due to the layer thickness being regulated by the discharge port of the conveying passage, so that sufficient frictional electrification is achieved. will be done. Further, since the entrance side of the conveyance path is larger than the discharge side to allow backflow of developer at this time, developer clogging does not occur.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The developing device of the present invention will be explained below with reference to the drawings. Incidentally, the same parts as those in the prior art will be given the same reference numerals and the explanation thereof will be omitted. In this embodiment, a layer thickness regulating member 12 that regulates the layer thickness of the developer carried and conveyed on the surface of the developing sleeve 8 of the developing roller 4 is shown in FIGS.
As shown in the figure, the developing sleeve 8 of the developing roller 4 extends while being curved in an arc shape.
A developer conveyance path 14 is formed between the surface and the surface. And the entrance 14 of the conveyance path 14
The dimension of A (in this case, the gap α) is made larger than the dimension of the discharge port 14B (in this case, the gap β) through which the developer is discharged while regulating the layer thickness, and the conveyance path for the layer thickness regulating member 12 is formed. Irregularities on the surface side to promote frictional charging of the developer 1
5. Furthermore, the amount of developer sent from the conveying roller 2 is regulated by the extending end 12A of the layer thickness regulating member 12 (at the gap α with the developing housing 1).

Therefore, in the developing device having such a structure, the developer conveyed from the conveying roller 2 is transferred to the extending end portion 12.
After the amount is regulated at A, when the carrier and toner are transported to the photosensitive drum 3 side through the transport path 14, the carrier and toner are strongly frictionally charged with each other, and the layer thickness regulating member 12 becomes uneven 15 during transport. By slidingly contacting the passage-forming surface side and also slidingly contacting excess developer that flows backward with the layer thickness regulated by the discharge port 14B, sufficient frictional electrification can be achieved so that uncharged toner is not generated. In this case, since the inlet size of the conveyance path is made larger than the outlet size, sufficient charging can be achieved without causing developer clogging. In this embodiment, a multi-stage development system in which a plurality of developing rollers are arranged for the photosensitive drum has been described, but the present invention is not limited to this, and a single developing roller may be arranged. Further, in this embodiment, a developing roller of the type that rotates the developing sleeve and fixes the internal magnet structure for development is described, but it is not a developing roller of the type that rotates both the developing sleeve and the internal magnet structure. It's okay.

[0009]

As described above, according to the developing device of the present invention, the layer thickness regulating member extends along the surface of the developing sleeve to form a developer transport path between the layer thickness regulating member and the developing sleeve surface. The size of the inlet of the conveyance path is larger than the size of the outlet through which the developer is discharged by regulating its layer thickness, so that the developer can be sufficiently triboelectrically charged without causing developer clogging. It is possible to improve conveyance performance and charging performance. Furthermore, since the unevenness for promoting frictional charging of the developer is formed on the conveyance path forming surface of the layer thickness regulating member rather than on the surface of the developing sleeve, when used in a high speed copying machine with a low circumferential speed ratio. Also, sufficient charging can be performed without adversely affecting the image.

[Brief explanation of drawings]

FIG. 1 is a sectional view of essential parts of a developing device of the present invention.

[Figure 2] An exploded perspective view.

FIG. 3 is a schematic cross-sectional view showing the configuration of a conventional developing device.

[Explanation of symbols]

4, 5 Developing roller 6, 7 Magnet structure 8, 9 Developing sleeve 12 Layer thickness regulating member 14 Conveyance path 14A Entrance 14B Discharge port 15 Unevenness

Claims (2)

[Claims] 1. A developing roller having a developing sleeve rotatably provided on the outside of a magnet structure fixed to a magnet roller shaft, and a layer thickness regulating the layer thickness of the developer carried and conveyed on the surface of the developing sleeve. In the developing device equipped with a regulating member, the layer thickness regulating member extends along the surface of the developing sleeve to form a developer conveying path between the layer thickness regulating member and the developing sleeve surface, and the inlet size of the conveying passage is A developing device characterized in that the layer thickness of the developer is regulated and the size of the discharge port is larger than that of the discharge port. 2. The developing device according to claim 1, wherein the conveying path forming surface of the layer thickness regulating member is provided with irregularities for promoting triboelectric charging of the developer.