IMAGE FORMING APPARATUS, DRUM UNIT, AND DEVELOPING UNIT

摘要

An image forming apparatus comprises image forming sections for each color, each including a pressure receiving parts pair in a first outer region of a first rotary body and a second rotary body as an image carrier and a developing roller. A first image forming section includes a first pressure receiving part of the first rotary body and a second pressure receiving part of the second rotary body as the pressure receiving parts pair. A second image forming section includes a third pressure receiving part of the first rotary body and a fourth pressure receiving part of the second rotary body as the pressure receiving parts pair. A protruding distance of the first pressure receiving part is smaller than a protruding distance of the third pressure receiving part. A protruding distance of the second pressure receiving part is larger than a protruding distance of the fourth pressure receiving part.

主权项

1. An image forming apparatus comprising:
a plurality of image forming sections for each color, each including an image carrier configured to rotate and carry a toner image during image forming and a developing part provided with a developing roller and configured to contain and apply toner to the image carrier by rotating the developing roller to form a toner image on the image carrier; and a press section configured to press at least one of the image carrier and the developing roller to the other to bring them in a press-contact state during image forming, wherein one of the developing roller and the image carrier is a first rotary body and the other is a second rotary body, and the first rotary body and the second rotary body define a toner image forming region in which the toner is applied from the developing roller to the image carrier, each of the image forming sections for each color includes a pair of pressure receiving parts provided in a first outer region located axially outside the toner image forming region, the image forming sections for each color include a first image forming section and a second image forming section, the first image forming section is configured to form a toner image of a first color and includes:
a first pressure receiving part provided to the first rotary body as one of the pair of pressure receiving parts and formed with a first pressure receiving surface contacted with the other one of the pair of pressure receiving parts in the press-contact state; anda second pressure receiving part provided to the second rotary body as the other one of the pair of pressure receiving parts and formed with a second pressure receiving surface contacted with the first pressure receiving surface in the press-contact state, the second image forming section is configured to form a toner image of a second color that is different from the first color, includes:
a third pressure receiving part provided to the first rotary body as one of the pair of pressure receiving parts and formed with a third pressure receiving surface contacted with the other one of the pair of pressure receiving part in the press-contact state; anda fourth pressure receiving part provided to the second rotary body as the other one of the pair of pressure receiving parts and formed with a fourth pressure receiving surface contacted with the third pressure receiving surface in the press-contact state, and the image forming apparatus is configured to satisfy both relationships expressed by:
L1L4 in which L1 denotes a protruding distance of the first pressure receiving part extending from a central axis of the first rotary body to the first pressure receiving surface, L2 denotes a protruding distance of the second pressure receiving part extending from a central axis of the second rotary body to the second pressure receiving surface, L3 denotes a protruding distance of the third pressure receiving part extending from the central axis of the first rotary body to the third pressure receiving surface, and L4 denotes a protruding distance of the fourth pressure receiving part extending from the central axis of the second rotary body to the fourth pressure receiving surface.