JPH0333259B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a developing device used in an electrophotographic device or the like, and more specifically, to developing a developer supplied on a carrier to a predetermined thickness using a layer forming member. The present invention relates to a nonmagnetic one-component developing device that has a developer layer and conveys this developer layer to an electrostatic latent image to develop the electrostatic latent image into a visible image.

(Prior Art) In this type of conventional developing device, developer stored in a hopper is conveyed to a carrier by a conveyance roll that contacts the carrier and rotates in the same direction as the carrier. Then, the developer transported onto the carrier is formed into a developer layer of a predetermined thickness by a layer forming member that is in line contact with the carrier with uniform pressure, and this developer layer is held on the carrier. It is known that the electrostatic latent image is supplied to an electrostatic latent image, and the electrostatic latent image is developed into a visible image.

It is known that in such a developing device, if the center line surface roughness (Ra) of the carrier is 10 μm or more, the developer will adhere to the surface of the carrier and will no longer be attracted to the electrostatic latent image. Therefore, the surface roughness of the carrier is set to be less than 10 μm in terms of center line average surface roughness (Ra).

For example, JP-A-55-113070 and JP-A-Sho
55-62469, Ra is 5 μm and 6 μm, respectively.
(6S) or higher rough surface supports are disclosed.

(Problems to be Solved by the Invention) However, even when the surface roughness of the carrier is less than 10 μm and 5 μm or more as described above, the developer layer formed on the carrier may deteriorate during long-term operation. There was a problem that the thickness became thinner, that is, the amount of developer conveyed decreased.

(Means for Solving the Problem) In order to solve the problem, the present invention provides an electrostatic charge held on a carrier by a developer layer formed on the carrier by a layer forming member. In a non-magnetic one-component developing device that develops a latent image into a visible image, the surface roughness of the carrier is defined as the center line average surface roughness (Ra).
It is characterized in that it is in the range of 0.1 to 0.5 μm.

(Example) Examples of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.
In the figure, 1 is a hopper that stores developer 2, and at both ends of the opening 1a of the hopper 1,
First and second blades 3, 4 are fixed, respectively. A transport roll 5 is disposed below the hopper 1 so as to be rotatable in the direction of an arrow 5b about a material shaft 5a. The free end side of the first blade 3 is in contact with the outer peripheral surface 5c of the transport roll 5 with a predetermined pressure. Reference numeral 6 denotes a carrier roll, which is rotatable in the direction of an arrow 6b around a material axis 6a, and its position is set so that it abuts against the outer circumferential surface 5c of the transport roll 5 with a predetermined pressure. The free end side of the second blade 4 is in contact with the outer peripheral surface 6c of the carrier roll 6 with a predetermined pressure. On the other hand, at a position facing the carrier roll 6, a holder roll 8 that holds the electrostatic latent image 7 is arranged so as to be rotatable in the direction of the arrow 8a. In addition, the carrier roll 6
A bias power source 9 applies a bias power source in which an alternating current voltage is superimposed on a direct current voltage.

The developer 2 stored in the hopper 1 is
It is a non-magnetic one-component developer, in which polarity control agents such as pigments such as carbon and metal-containing azo dyes are dispersed in various thermoplastic resins such as styrene resins and acrylic resins, and then pulverized and classified. The size is 20μ. In some cases, hydrophobic silica may be added in an amount of 0.5 to 20 percent by weight based on the developer particles in order to improve fluidity. Next, the first blade 3 is made of a stainless steel plate with a predetermined thickness, and the developer 2 is applied to the blade 3.
It is in contact with the outer circumferential surface 5c of the transport roll 5 with a linear pressure that does not fall out from between the transport roll 5 and the transport roll 5. The second blade 4 is also made of a stainless steel plate, and functions as a layer forming member that forms a developer layer of a predetermined thickness on the outer peripheral surface 6c of the carrier 6.

Next, the surface roughness of the outer peripheral surface 6c of the carrier roll 6 is processed so that the centerline surface roughness (Ra) is within the range of 0.1 μm to 0.5 μm.

That is, the inventor investigated the amount of developer conveyed by the carrier by changing the centerline surface roughness (Ra) of the carrier surface, and found that the centerline surface roughness (Ra)
It has been found that within the range of 0.1 μm to 0.5 μm, the amount of developer conveyed toward the electrostatic latent image is maintained constant even during long-term use. Figure 2 shows center line average surface roughness of 0.05μm, 0.3μm and 0.7μm.
The experimental results for the cases are shown by curves A, B, and C, respectively. As is clear from the figure, when the surface roughness is 0.3 μm (curve B), the amount of developer conveyed by the carrier remains almost constant even during long-term continuous operation; It will not gradually decrease like this.

The operation of this embodiment configured as described above will be described. First, the developer 2 in the hopper 1 falls from the opening 1a due to its own weight and is supplied onto the outer circumferential surface 5c of the transport roll 5. The developer 2 thus supplied is conveyed toward the carrier roll 6 by the conveyance roll 5 . At the contact portion between both rolls 5 and 6, the developer is transferred from the transport roll 5 onto the outer circumferential surface 6c of the carrier roll 6. During this movement, the developer is triboelectrically charged due to the rubbing between the rolls 5 and 6, and is given a sufficient charge. The developer on the carrier roll 6 reaches a contact position with the second blade (layer forming member) 4 due to the rotation of the roll 6,
This blade 4 forms a developer layer of a predetermined thickness. Furthermore, the friction between the blade 4 and the roll 6 imparts a sufficient charge to the developer layer.

Here, in this embodiment, as described above, the surface roughness of the outer peripheral surface 6c of the carrier roll 6 is set in the range of 0.1 to 0.5 μm in terms of center line average surface roughness (Ra), so The amount of developer conveyed by the carrier roll 6 remains constant even when the carrier roll 6 is used continuously. That is, the thickness of the developer layer formed by the blade 4 is constant.

In this way, a developer layer having a constant layer thickness is always formed on the outer peripheral surface 6c of the carrier roll 6 after passing through the blade 4. As the roll 6 rotates, this developer layer reaches a position facing the holder 8. The holder 8 is rotating in the direction of the arrow 8a, and when the electrostatic latent image 7 held on its outer peripheral surface reaches this opposing position, the carrier roll 6 is rotating while being applied with a bias voltage. Due to the electric field between the electrostatic latent image 7 and the carrier roll 6,
The developer on the carrier roll 6 is attracted to the electrostatic latent image 7 and adheres thereto. In this way,
The latent image 7 is developed.

(Effects of the Invention) As explained above, according to the present invention, the surface roughness of the developer carrying surface, which is the surface of the carrier, is within the range of 0.1 to 0.5 μm in terms of center line average surface roughness (Ra). Therefore, the electrostatic latent image is conveyed toward the holder holding the electrostatic latent image. The amount of developer conveyed is always constant, and uniform and stable development can be performed.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an embodiment of the present invention;
FIG. 2 is a characteristic curve diagram showing changes in the amount of developer conveyed due to differences in surface roughness of the carrier. 2...Developer, 4...Second blade (layer forming member), 6...Carrier roll, 6c...Outer peripheral surface,
7... Electrostatic latent image.

Claims (1)

[Claims] 1. A carrier carrying a developer, a transport roll that presses against the carrier and supplies the developer to the carrier, and a carrier on the carrier downstream of the pressure contact portion of the carrier with the transport roll. In a non-magnetic one-component developing device equipped with a layer forming means that forms a thin layer of the supplied developer and applies an electric charge, the surface roughness of the carrier is set to a center line average roughness (Ra) of 0.1 to 0.5 μm. A non-magnetic one-component developing device characterized by comprising: