JPH0462391B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a developing device using a one-component developer, and more particularly to a developing device suitable for an image forming device using an electrostatic latent image such as an electrophotographic camera. It is related to.

PRIOR ART In general, in a developing method using a one-component developer such as in an electrophotographic copying machine, it is necessary to uniformly form a thin layer of toner as a developer and apply a necessary charge to the toner for development. As a specific means, a layer thickness regulating member made of an elastic blade or a magnetic material is brought into sliding contact with almost the entire width direction of the rotating toner carrier to regulate the toner layer thickness, thereby simultaneously obtaining a thin toner layer. A well-known method is to apply the necessary charge to the toner during development using frictional charging at this time. In this case, in addition to the toner not being consumed at both ends of the circumferential surface of the toner carrier, which often correspond to non-image areas, the toner moves due to its diffusion effect as the toner carrier rotates. This causes inconveniences such as oversupply of toner and scattering of toner, contaminating the inside of the machine.

In order to prevent these inconveniences, in conventional developing devices, flexible sealing members are provided between both sides of the layer thickness regulating member and the toner carrier, where toner tends to be oversupplied. This effectively prevents the formation of a thin layer of toner in this area, thereby preventing oversupply of toner. However, in this method, if the layer thickness regulating member has elasticity, the provision of the sealing member deforms and the layer thickness regulating force at the sliding contact portion becomes uneven. When a supported elastic blade is used, the regulating force near the sealing member is weak, so toner is often supplied excessively to this area.

Purpose The present invention has been made in view of the above points, and is a developing device that has a simple structure, prevents oversupply of toner, avoids contamination inside the machine due to oversupplied toner, and promotes effective use of toner. The purpose is to provide equipment.

Configuration The configuration of the present invention will be described below based on specific examples. FIG. 1 is a schematic diagram showing the developing device of the present invention applied to an electrophotographic copying machine, and FIG.
The figure is a perspective view showing the main parts, and FIG. 3 is a plan view thereof. In FIG. 1, a sleeve 2 as a cylindrical toner carrier is rotatably supported, and is rotated at a predetermined speed in the direction of the arrow to carry and convey toner 1 on its circumferential surface. sleeve 2
A cylindrical magnet 3 is disposed coaxially and rotatably with the sleeve 2, and in this example, the sleeve 2
is rotated in the same direction as the direction of rotation. Note that the rotation directions of the sleeve 2 and the magnet 3 can be arbitrarily selected depending on the purpose, and it is also possible to fix one of them in a non-rotating state. As for the respective rotational speeds, it is preferable to set the rotational speed of the magnet 3 to about 1800rpm, for example, while the sleeve 2 has a rotational speed of 400rpm.

A hopper 4 is disposed over a predetermined area near the circumferential surface of the sleeve 2 for storing the magnetic toner 1 and replenishing the circumferential surface of the sleeve 2 in an appropriate amount. magnetic toner 1
is a so-called one-component high-resistance magnetic toner in which magnetic powder is mixed in resin, and the average particle size is adjusted to about 6 μm.

On the downstream side of the hopper 4 in the direction of rotation of the sleeve 2, a blade 5 made of a sufficiently elastic magnetic material such as SK material having a thickness of about 0.1 mm is disposed. As shown in FIG. 3, this blade 5 is provided so as to be in sliding contact with the sleeve 2 over almost the entire widthwise area of the sleeve 2, and is supplied to the circumferential surface of the sleeve 2 from the hopper 4 and conveyed. The amount of toner 1 is regulated to form a thin toner layer 1a. The blade 5 has one end rotatably supported around a shaft 5a, and the other free end of the blade 5 which uniformly applies a moderate and stable pressing force to the sleeve circumferential surface due to the magnetic force of a magnet 3 installed inside the sleeve 2. The toner thin layer 1 formed by this is provided so as to be pressed against the
The layer thickness of a is stabilized.

A pair of seal members 6 are disposed on both sides of the free end of the blade 5 to prevent excessive supply of toner to both ends of the circumferential surface of the sleeve 2. The sealing member 6 is made of a flexible material such as Moltoprene, and is in close contact with both sides of the free tip of the blade 5 and the surrounding area of the sleeve 2, as shown in FIG. contact,
The toner 1 is prevented from coming into contact with this region to prevent its oversupply. In this case, since the sealing member 6 is flexible, it can flexibly follow the step difference due to the thickness of the blade 5 and easily obtain the desired close contact state. In this example, the seal member 6
is fixed at one end to the bottom of the hopper 4, and is erected so that its tip is higher than the free tip position of the blade 5. Furthermore, as shown in FIG. 3, by making the separation distance L between the pair of seal members 6, 6 approximately coincide with the effective image area W on the circumferential surface of the sleeve 2, the supply of excess toner can be more efficiently prevented. Ru. By configuring the sealing member 6 in this way, toner is effectively prevented from being supplied to the non-image area or outside, and its flexibility allows it to freely approach the circumferential surface of the sleeve 2 at the tip of the blade 5. The inconvenience of restricted movement is also avoided. Incidentally, as shown in FIG. 4, the sealing member 6 can also be constructed using a relatively thin member such as Mylar.

Returning to FIG. 1, on the downstream side of the above-described placement position of the blade 5 on the circumferential surface of the sleeve 2, for example, in a position substantially opposite to the blade 5 as in this example, there is a position that is rotated in the direction of the arrow. An endless OPC belt (organic photoreceptor belt) 7 is disposed, and a rotationally driven sleeve 2 is in rolling contact with the surface of the OPC belt 7, and is supported in a thin layer on the circumferential surface of the sleeve 2. Toner 1
a is supplied to the surface of the OPC belt 7. While the OPC belt 7 is driven at a constant speed in the direction of the arrow, its surface is uniformly charged with a predetermined polarity, imagewise exposed, and an electrostatic latent image is formed. The installation position of the device is reached, where the toner thin layer 1
The electrostatic latent image is turned into a visible image by being supplied with a.

Next, the operation of the above embodiment having such a configuration will be explained.

Sleeve 2 rotates in the direction of the arrow at a predetermined speed
An appropriate amount of magnetic toner 1 is supplied from the hopper 4 onto the surface of the toner. In this case, the toner 1 in the hopper 4 moves toward the circumferential surface of the sleeve 2 due to the magnetic force of the agitator (not shown) provided in the hopper 4 and the magnet 3 provided in the sleeve 2. Seal members 6 are in contact with both sides and both ends of the circumferential surface of the sleeve 2 in the vicinity thereof to prevent the toner 1 from coming into contact with the circumferential surface of the sleeve 2. Therefore, the toner 1 tends to spread in the axial direction of the sleeve 2 as the magnet 3 and the like rotate, but this is prevented by the seal member 6, and excessive supply of the toner 1 to this region is avoided.

In this way, the toner 1 selectively supplied within the effective image area width W on the circumferential surface of the sleeve 2 has its layer thickness regulated by the blade 5 as the sleeve 2 rotates, and a thin toner layer 1a is formed within the area. is formed. At this time, the toner 1 is triboelectrically charged to a predetermined polarity, for example, positive, and is given the charge necessary for development. In this case, as described above, since the sealing member 6 is flexible, it does not restrict the layer thickness regulating operation on the free end side of the blade 5, and stably forms the thin toner layer 1a with a predetermined thickness. I can do things.

The toner thin layer 1a, which is charged with the charge necessary for development and is uniformly thinned, is conveyed to the development position where it rolls into contact with the OPC belt 7 as the sleeve 2 rotates. An electrostatic latent image is formed on the surface of the OPC belt 7 through uniform charging and image exposure processes at appropriate locations, and a thin toner layer 1a is supplied to this to make the electrostatic latent image visible. . In this case, a thin toner layer 1 is placed on both ends of the circumferential surface of the sleeve 2 corresponding to the non-image area.
Since the toner a is not supported, the inconvenience that excessively supplied toner that is not used for development scatters and contaminates the inside of the machine can be prevented.

The circumferential surface of the sleeve 2 after the above development process is
As the hopper rotates, the static electricity is eliminated by a static elimination brush (not shown) etc. disposed on the downstream side, and then the hopper 4
, and a similar development process for the next cycle is started.

Effects As detailed above, according to the present invention, by covering the tip of the layer thickness regulating member in a predetermined region and the surface of the toner carrier in the vicinity with a flexible sealing member, the layer thickness regulating operation can be improved. Unnecessary excessive supply of toner to the toner carrier is suppressed without adversely affecting the toner carrier. Therefore, scattering of excessively supplied toner is avoided, contamination inside the machine is prevented, and toner yield is improved. It should be noted that the present invention is not limited to the specific embodiments described above, and it goes without saying that various modifications can be made within the technical scope of the present invention.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention, FIG. 2 is a perspective view showing essential parts of one embodiment of the present invention,
FIG. 3 is a plan view showing essential parts of one embodiment of the present invention, and FIG. 4 is a schematic diagram showing another embodiment of the present invention. Explanation of symbols, 2...Sleeve, 4...Hoppa,
5...Blade, 6...Seal member.

Claims (1)

[Claims] 1. In a developing device that performs development by supplying a thin layer of toner to an electrostatic latent image on an image carrier, a toner carrier that moves the toner to a development position and a tip surface that slides with the toner carrier are used. a layer thickness regulating member that contacts to form a toner layer of a predetermined thickness on the toner carrier; and an elastic sealing member that covers both sides of the tip of the layer thickness regulating member from the back side of the tip. A developing device characterized by: