JP-7855863-B2 - Developing apparatus and image forming apparatus equipped therewith

Inventors

• 藤島 正之
• 村田 貴彦
• 江木 誠
• 三宅 尚史

Assignees

• 京セラドキュメントソリューションズ株式会社

Dates

Publication Date

20260511

Application Date

20220204

Claims (4)

1. A developing container for containing a magnetic one-component developer consisting only of magnetic toner, A developer carrier is rotatably supported in the developing container, carries the developer on its outer surface, and is exposed from the opening of the developing container and faces the image carrier, One or more stirring and conveying members are rotatably supported in the developing container and convey the developer inside the developing container while stirring it, A restricting member is positioned at a predetermined distance from the developer carrier and forms a restricting portion that restricts the thickness of the developer layer supported on the developer carrier. A magnetic member is fixed inside the developer carrier in a manner that prevents rotation, and has multiple magnetic poles, including a main pole facing the image carrier and a restricting pole facing the restricting member. A developing apparatus comprising the above, for developing an electrostatic latent image formed on the image carrier, When not forming an image, the developer carrier can be rotated in the opposite direction to the rotation direction during image formation to perform a developer removal operation to remove the developer that has accumulated between the regulating member and the developer carrier. The upper limit of the reverse rotation angle of the developer carrier in the developer removal operation is the angle from the start of reverse rotation until the first opposing position of the developer carrier, which is opposite to the downstream end in the reverse rotation direction of the area where the developer is present in the developing container, moves to the edge of the opening. The lower limit of the reverse rotation angle is the angle at which the second opposing position of the developer carrier facing the regulating member at the start of reverse rotation moves to a position that exceeds the minimum point of the magnetic force distribution between the regulating pole and the adjacent pole positioned adjacent to the regulating pole on the downstream side of the regulating pole with respect to the reverse rotation direction of the developer carrier. A developing apparatus characterized in that, when the magnetic force of the restricting pole is M1 [mT], the magnetic force of the adjacent pole is M2 [mT], and the angle between the restricting pole and the adjacent pole as viewed from the center of the magnetic member is α [°], the angle θm from the restricting pole to the minimum point is calculated by the following equation (1), and the lower limit of the reverse rotation angle is set to an angle greater than the angle θm. θm=α×M1/(M1+M2)...(1)
2. The developing apparatus according to claim 1, characterized in that the reverse rotation angle is greater than the angle to a position beyond the minimum point, and less than or equal to the magnetic force peak position of the adjacent pole .
3. The developing container has a first transport chamber and a second transport chamber arranged in parallel to each other. The agitation and conveying member comprises a first agitation and conveying member that conveys the developer in the first conveying chamber in a first direction while agitating it, and a second agitation and conveying member that conveys the developer in the second conveying chamber in a second direction opposite to the first direction while agitating it. The developer carrier is positioned adjacent to the second stirring and conveying member so as to receive the developer from the second stirring and conveying member into the second conveying chamber. The developing apparatus according to claim 1 or 2, characterized in that the adjacent electrode is a pumping electrode that pumps the developer in the second transport chamber to the developer carrier .
4. An image forming apparatus comprising a developing apparatus according to any one of claims 1 to 3 .

Description

This invention relates to a developing apparatus used in image forming devices such as photocopiers, facsimile machines, and printers, and more particularly to a method for suppressing clogging of the developing agent in the gap between the developing roller and the regulating blade. Conventionally, in image forming apparatuses using electrophotographic processes, the development method primarily involves the use of powdered developers. This process typically involves visualizing (developing) an electrostatic latent image formed on an image carrier such as a photoreceptor drum using the developer, transferring the resulting visible image (toner image) onto a recording medium, and then performing a fixing process. One known development method using a developer is the magnetic single-component development method, which uses a single-component developer consisting solely of magnetic toner. In this method, a fixed magnet with multiple magnetic poles is placed inside the developing roller (developer carrier). The toner in the developing container is then loaded onto the developing roller using magnetic force. A regulating blade (regulating member) is then used to regulate the layer thickness, forming a thin toner layer. At the development position, the toner is then launched to the photoreceptor drum. In a single-component magnetic development system, sufficient magnetic force is required at the tip of the regulating blade to ensure the stability of the toner layer on the developing roller and to improve the performance of charging the toner. However, if development is performed continuously, the toner tends to soften and aggregate around the regulating blade within the developing device. Because the softened toner has a different magnetic restraining force than other parts, it causes disturbances in the toner layer on the developing roller. As a result, image defects such as variations in density and white streaks are more likely to occur when outputting halftone images. Therefore, Patent Document 1 discloses an image forming apparatus that prevents toner accumulated on the developer regulating member from being developed into the image by rotating the developer carrier in the opposite direction to that used during development, while the image carrier is stopped. Japanese Patent Publication No. 2009-258276 A schematic cross-sectional view of an image forming apparatus 100 equipped with the developing device 4 of the present invention.Side cross-sectional view of a developing apparatus 4 according to one embodiment of the present inventionSide cross-sectional view of the toner container 5 mounted on the image forming apparatus 100.Block diagram showing an example of a control path used in the image forming apparatus 100.A side view showing the reverse rotation angle of the developing roller 25 when the developer removal operation is performed in the developing apparatus 4 of this embodiment.A schematic diagram showing the relationship between the vertical magnetic force distribution of the fixed magnet 27 and the lower limit value θ2 of the reverse rotation angle of the developing roller 25 in the developing apparatus 4 of this embodiment.Enlarged view of the area around the developing roller 25 and the second agitation and transport screw 24 in Figure 5. The embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a schematic cross-sectional view of an image forming apparatus 100 equipped with a developing device 4 of the present invention. In the image forming apparatus (e.g., a monochrome printer) 100, when printing is performed, an electrostatic latent image is formed in the image forming unit 9 within the main body of the image forming apparatus 100 based on original image data transmitted from a personal computer (not shown, hereinafter abbreviated as PC), and toner is attached to the electrostatic latent image by the developing device 4 to form a toner image. Toner is supplied to the developing device 4 from the toner container 5. In the image forming apparatus 100, the image forming process on the photoreceptor drum 1 is performed while the photoreceptor drum 1 is rotated clockwise in Figure 1. The image forming unit 9 is equipped with a charging unit 2, an exposure unit 3, a developing device 4, a transfer roller 7, a cleaning device 8, and a static elimination device (not shown), all arranged along the rotation direction (clockwise) of the photosensitive drum 1. The photosensitive drum 1 is, for example, an aluminum drum with a photosensitive layer laminated on top. While the photosensitive layer is not particularly limited, preferred materials include amorphous silicon (a-Si), which offers excellent durability, and organic photosensitive layers (OPC), which generate less ozone during charging and allow for high-resolution images. The charging unit 2 uniformly charges the photosensitive layer on the surface of the photoreceptor drum 1. For example, the ch