Developing device and image forming apparatus

Patent metadata

Field	Value
Publication number	US-2016139541-A1
Application number	US-201514931705-A
Country	US
Kind code	A1
Filing date	Nov 3, 2015
Priority date	Nov 19, 2014
Publication date	May 19, 2016
Grant date	—

Abstract

A developing device includes a developer carrying member and first and second conveyance members. The first conveyance member conveys a developer in a first direction through a first conveyance path to the developer carrying member. The second conveyance member conveys the developer in a second direction through a second conveyance path included in a circulation path along with the first conveyance path. The second conveyance member has a helical second screw around a second shaft. The second conveyance path includes a developer replenishing port and a developer discharge port. The second screw is approximately constant in diameter in a second section being a portion extending a predetermined distance from an end of the discharge port in the second direction when viewed in a top view. The second screw conveys the developer at a lower speed in the second section than on an upstream side with respect to the second section.

First claim

1 . A developing device comprising:
a developer carrying member; a first conveyance member conveying a developer in a first direction through a first conveyance path and supplying the developer to the developer carrying member; and a second conveyance member conveying the developer in a second direction through a second conveyance path included in a circulation path along with the first conveyance path, the second conveyance member having a helical second screw around a second shaft, wherein, the second conveyance path includes a developer replenishing port, and the second conveyance path includes a developer discharge port provided in a top portion, and the second screw has an approximately constant diameter in a second section being a portion extending a predetermined distance in the second direction from an end of the discharge port in the second direction when viewed in a top view, the second screw being adapted to be capable of conveying the developer at a lower speed in the second section than on an upstream side with respect to the second section.

2 . The developing device according to claim 1 , wherein the discharge port is positioned higher than the second conveyance path and communicates with the second conveyance path.

3 . The developing device according to claim 1 , wherein S 1 and S 2 satisfy (S 1 −S 2 )/S 2 <1, where S 1 is the area of the second conveyance path in the second section when viewed in the second direction, and S 2 is the area of the second screw in the second section when viewed in the second direction.

4 . The developing device according to claim 3 , wherein (S 1 −S 2 )/S 2 falls within the range from 0.2 to 0.4.

5 . The developing device according to claim 1 , wherein the second section of the second screw, when viewed in a top view, further includes a portion extending from an arbitrary position enclosed within the discharge port to the end of the discharge port in the second direction.

6 . The developing device according to claim 1 , wherein the second screw has a narrower pitch in the second section than on the upstream side with respect to the second section.

7 . The developing device according to claim 1 , wherein,
the second shaft is thicker in the second section than on the upstream side with respect to the second section, and the diameter of the second screw is approximately constant both in the second section and on the upstream side with respect to the second section.

8 . The developing device according to claim 1 , wherein,
the second conveyance path, when viewed in a plan view in the second direction, has a smaller area in the second section than on the upstream side with respect to the second section, the second screw has a smaller diameter in the second section than on the upstream side with respect to the second section, and the second conveyance path has an inner surface spaced apart from an outer edge of the second screw at approximately the same distance both in the second section and on the upstream side with respect to the second section.

9 . An image forming apparatus comprising a developing device according to claim 1 .

Assignees

• Konica Minolta Inc

Inventors

• Inada Yasuyuki
• Mukobayashi Yu
• Mandai Yuusuke
• Nakayama Kanji
• Yoshimoto Shinichi
• Kanda Junji

Classifications

• G03G15/0893

  in a closed loop within the sump of the developing device · CPC title

• G03G15/0891 Primary

  for conveying or circulating developer, e.g. augers · CPC title