Patent ID: 9327925
Filing Date: 2016-05-03
CPC Classification: B65H

Claim Text:
1. An image forming apparatus comprising: an apparatus body; a paper feed cassette attachable to and detachable from the apparatus body; a rotary operating member rotatably mounted to the paper feed cassette; an engaging portion provided in the paper feed cassette and configured to engage the rotary operating member with the paper feed cassette at predetermined angular intervals; a plurality of engaged portions provided in the rotary operating member, any one of the engaged portions being engaged by the engaging portion; and a size detection switch mounted to the apparatus body and configured to detect a size of a recording medium stored in the paper feed cassette, wherein the rotary operating member includes a pressure portion configured to activate the size detection switch, each of the engaged portions is configured to release engagement with the engaging portion in response to a rotational force equal to or greater than a predetermined value applied to the rotary operating member, a rotational force in a first direction necessary for causing the engagement to be released is greater than a rotational force in a second direction necessary for causing the engagement to be released, the second direction being reverse of the first direction, the plurality of engaged portions are disposed on a lower edge of the rotary operating member in a circumferential direction of the rotary operating member, the engaging portion is disposed below the rotary operating member and at a position on a circumference of a circle opposing the engaged portions, each of the engaged portions has an asymmetric profile in the circumferential direction, the engaging portion has an asymmetric profile in the circumferential direction, either the notch is a triangular notch, each of the engaged portions has a first edge and a second edge defining the triangular notch, the projection is a triangular projection, the engaging portion has a third edge and a fourth edge defining the triangular projection, an angle formed by the first edge of each of the engaged portions relative to a rotation axis of the rotary operating member is θ1, and an angle formed by the second edge of each of the engaged portions relative to the rotation axis is θ2, where θ1>θ2>0° is satisfied, an angle formed by the third edge of the engaging portion confronting one of the first edges relative to the rotation axis is θ1, and an angle formed by the fourth edge of the engaging portion confronting one of the second edges relative to the rotation axis is θ2, and in response to rotation of the rotary operating member in the second direction, the first edge of one of the engaged portions comes into contact against the third edge of the engaging portion.