Color image forming apparatus

• US 6,249,663 B1
• Filed: 09/13/2000
• Issued: 06/19/2001
• Est. Priority Date: 11/05/1996
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Alzawa, Masahiro, Yoshikawa, Masanori, Asakura, Kenji, Katakabe, Noboru
• Primary Examiner(s): Chen, Sophia S.
• Application Number:
  US09/661,390
• Time in Patent Office: 279 Days
• Field of Search: 399/167, 399/227, 399/223, 399/112, 399/117, 399/116, 399/111, 399/36
• US Class Current: 399/167
• CPC Class Codes: G03G 15/0121 for developing
• CPC Class Codes: G03G 15/0194 primary transfer to the final recording medium G03G15/0184 takes precedence
• CPC Class Codes: G03G 2215/0116 Rotating set of recording members

Abstract

A color image forming apparatus is provided, and includes a plurality of image forming units including a photosensitive drum, a charging device and a developing device; a carriage for retaining and rotating the plurality of image forming units so as to move the image forming units between an image forming position and a waiting position; an exposing device for exposing a surface of the photosensitive drum of the image forming unit located at the image forming position; an intermediate transfer belt for successive transfer and superposition of toner images of various colors from the photosensitive drum of the image forming units located at the image forming position so as to form a color toner image; a driving member for driving the photosensitive drum and the intermediate transfer belt; a position detector for detecting a reference position of the intermediate transfer belt when the intermediate transfer belt is driven, and outputting a reference position detection signal; a secondary transfer roller for transferring the color toner image on the intermediate transfer belt onto recording paper; and a controller for controlling the operation of the above structural elements. The controller determines an operation start time of the charging device and the developing device using a rotation command signal to the driving member as a reference, and an operation start time of the exposing device, the intermediate transfer belt and the secondary transfer roller using the reference position detection signal as a reference.

Claims

1. 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; and

a 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; and

the 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; and

a 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, and

after 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.

2. The color image forming apparatus according to claim 1, wherein the image forming unit is positioned with respect to the machine body on the other side of the shaft line of the photosensitive drum shaft, the center of the output shaft and that of the photosensitive drum shaft coincide on the one side of the shaft line of the photosensitive drum shaft, thus enabling the rotation force of the output shaft to be transmitted to the photosensitive drum.

3. The color image forming apparatus according to claim 1, wherein the protrusion of the image forming unit receives a thrust force applied to the image forming unit, positioned at the image forming position, from the output shaft when the output shaft moves from the separated position to the guided position while the protrusion being in contact with the guide plate of the machine body, then 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.

4. The color image forming apparatus according to claim 1, wherein the image forming unit is attached/removed in a direction perpendicular to axial directions of the transfer body and the photosensitive drum shaft.

5. An image forming unit, comprising:

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 a tapered tip of an output shaft of a machine body 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 a first coupling provided in the output shaft, the second coupling being provided on the one side of the image forming unit and being fixed to the photosensitive drum shaft; and

a protrusion guided by a guide plate of the machine body to be positioned at a predetermined location, the protrusion being provided on the other side of the image forming unit,

wherein the conical concave surface and the second coupling are positioned on one side of a shaft line of the photosensitive drum shaft, and the protrusion is positioned on the other side of the shaft line of the photosensitive drum shaft.

6. 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; and

a first coupling provided in the output shaft;

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; and

a 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; and

a 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 by 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, and

when the image forming unit is positioned at an image forming position, the output shaft moves from the separated position to the guided position, the protrusion of the image forming unit receives a thrust force applied to the image forming unit from the output shaft while being in contact with a guide plate of the machine body, then 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.

7. The color image forming apparatus according to claim 6, wherein the image forming unit is received by the machine body on the other side of the shaft line of the photosensitive drum shaft, and the center of the output shaft and that of the photosensitive drum shaft coincide on the one side of the shaft line of the photosensitive drum shaft, thus enabling the rotation force of the output shaft to be transmitted to the photosensitive drum.

8. The color image forming apparatus according to claim 6, wherein after 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, and the protrusion of the image forming unit receives a thrust force applied to the image forming unit from the output shaft while being in contact with the guide plate of the machine body.

9. The color forming apparatus according to claim 6, wherein the image forming unit is attached/removed in a direction perpendicular to axial directions of the transfer body and the photosensitive drum shaft.

10. An image forming unit, comprising:

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 a tapered tip of an output shaft of a machine body 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 a first coupling provided in the output shaft, the second coupling being provided on the one side of the image forming unit and being fixed to the photosensitive drum shaft; and

a protrusion provided on the other side of the image forming unit and receiving a thrust force applied to the image forming unit from the output shaft while being in contact with a guide plate of the machine body when the image forming unit is positioned at an image forming position,

wherein the conical concave surface and the second coupling are positioned on one side of a shaft line of the photosensitive drum shaft, and the protrusion is positioned on the other side of the shaft line of the photosensitive drum shaft.