Patent ID: 6249663
Filing Date: 2001-06-19
Classification: G03G

Abstract:
A color image forming apparatus, comprising:a machine body including:an output shaft supported rotatably, which has a convex tapered tip formed at its distal end;a first coupling provided in the output shaft; anda guide plate for guiding a protrusion in the vicinity of an image forming position to position the protrusion at a predetermined location;an image forming unit, including:a photosensitive drum;a photosensitive drum shaft, which is supported rotatably and supports the photosensitive drum;a conical concave surface that is provided on one side of the image forming unit and guides the convex tapered tip of the output shaft so that a center of the output shaft and that of the photosensitive drum shaft coincide;a second coupling for transmitting a rotation force of the output shaft to the photosensitive drum shaft by engaging with the first coupling, the second coupling being provided on the one side of the image forming unit and being fixed to the photosensitive drum shaft; andthe protrusion provided on the other side of the image forming unit;wherein the conical concave surface and the second coupling are positioned on one side on a shaft line of the photosensitive drum shaft, and the protrusion is positioned on the other side on the shaft line of the photosensitive drum shaft; anda transfer member for superposing toner images formed on the photosensitive drum on a transfer body successively to transfer the toner images,wherein the output shaft is configured to be movable in a direction of its axis so as to be positioned at a separated position where the tapered tip is away from the conical concave surface of the image forming unit and at a guided position where the tapered tip is guided to the conical concave surface of the image forming unit, and in a direction that the output shaft moves perpendicularly to a direction that the image forming unit is attached or removed, andafter the protrusion is guided by the guide plate to position the image forming unit at the image forming position, the output shaft moves from the separated position to the guided position, the tapered tip of the output shaft is guided by the conical concave surface of the image forming unit, and the first coupling and the second coupling are engaged while the center of the output shaft and that of the photosensitive drum shaft coincide, thus enabling the rotation force of the output shaft to be transmitted to the photosensitive drum.