Secondary transfer device

Patent metadata

Field	Value
Publication number	US-2020356021-A1
Application number	US-202016849423-A
Country	US
Kind code	A1
Filing date	Apr 15, 2020
Priority date	May 7, 2019
Publication date	Nov 12, 2020
Grant date	—

Abstract

There is provided a secondary transfer device for secondary-transferring a toner image primary-transferred on an outer peripheral surface of an endless annular intermediate transfer belt to a sheet at a predetermined secondary transfer position, the intermediate transfer belt having a predetermined width and being wound around a plurality of rollers and rotating, the secondary transfer device including: a pressure-releasing mechanism that displaces a secondary transfer roller to a pressing position and a separation position; a first drive that drives the pressure-releasing mechanism; a high-speed depressurization mechanism that temporarily depressurizes a nip pressure, at which the secondary transfer roller at the pressing position interposes and presses the intermediate transfer belt in a gap with respect to the opposite roller, when a leading end and a tailing end of a sheet pass between the secondary transfer roller and the intermediate transfer belt; and a second drive that drives the high-speed depressurization mechanism.

First claim

What is claimed is:

1 . A secondary transfer device for secondary-transferring a toner image primary-transferred on an outer peripheral surface of an endless annular intermediate transfer belt to a sheet at a predetermined secondary transfer position, the intermediate transfer belt having a predetermined width and being wound around a plurality of rollers and rotating, the secondary transfer device comprising:
a pressure-releasing mechanism that displaces a secondary transfer roller to a pressing position where the intermediate transfer belt is interposed and pressed between the secondary transfer roller and an opposite roller that abuts an inner peripheral surface of the intermediate transfer belt at the secondary transfer position, and a separation position separated from the outer peripheral surface of the intermediate transfer belt; a first drive that drives the pressure-releasing mechanism; a high-speed depressurization mechanism that temporarily depressurizes a nip pressure, at which the secondary transfer roller at the pressing position interposes and presses the intermediate transfer belt in a gap with respect to the opposite roller, when a leading end and a tailing end of a sheet pass between the secondary transfer roller and the intermediate transfer belt; and a second drive that drives the high-speed depressurization mechanism, wherein the pressure-releasing mechanism and the high-speed depressurization mechanism are arranged such that projected images when projected in an axial direction of the secondary transfer roller overlap.

2 . The secondary transfer device according to claim 1 ,
wherein the pressure-releasing mechanism includes a pressing cam that is supported to a rotation shaft driven by the first drive in the same direction as an axis of the secondary transfer roller, and a pressing arm that abuts on the pressing cam and swings to displace the secondary transfer roller to the pressing position and the separation position, the high-speed depressurization mechanism includes a depressurization cam that is supported to a rotation shaft driven by the second drive in the same direction as an axis of the secondary transfer roller, and a depressurization arm that abuts on the depressurization cam and swings to displace the axis of the secondary transfer roller in the pressing position in a direction in which the nip pressure decreases, and the projected images of the pressing cam and the depressurization cam overlap with each other.

3 . The secondary transfer device according to claim 2 ,
wherein the rotation shaft of the pressing cam and the rotation shaft of the depressurization cam are coaxial.

4 . The secondary transfer device according to claim 3 ,
wherein a maximum diameter of the pressing cam is smaller than a minimum diameter of the depressurization cam.

5 . The secondary transfer device according to claim 3 ,
wherein a minimum diameter of the pressing cam is larger than a maximum diameter of the depressurization cam.

6 . The secondary transfer device according to claim 3 ,
wherein the pressing arm and the pressing cam are provided at two locations separated at both ends in an axial direction of the secondary transfer roller, and the depressurization cam is disposed inside these two locations.

7 . The secondary transfer device according to claim 6 ,
wherein the depressurization arms are provided at two locations separated at both ends in the axial direction of the secondary transfer roller, and locations of force points of these depressurization arms are connected to each other by a connecting member, the depressurization cam is disposed at a center in the axial direction of the secondary transfer roller, and the connecting member abuts on the depressurization cam, and the depressurization arm swings.

8 . The secondary transfer device according to claim 6 ,
wherein the depressurization arms are provided at two locations separated at both ends in the axial direction of the secondary transfer roller, and locations of force points of these depressurization arms are connected to each other by a connecting member, the depressurization cams are disposed near an inside of the pressing cam, respectively, and the connecting member abuts on the depressurization cam, and the depressurization arm swings.

9 . The secondary transfer device according to claim 6 ,
wherein the depressurization cams are disposed near the inside of the pressing cam, respectively, and a position detector that detects an angular position of the second drive and the depressurization cam is disposed inside the two depressurization cams.

10 . The secondary transfer device according to claim 2 ,
wherein the depressurization arm abuts on the depressurization cam with a rotating body.

11 . The secondary transfer device according to claim 2 ,
wherein a rotation fulcrum of the depressurization arm is located between a force point where the depressurization arm receives a force from the depressurization cam and a working point where the depressurization arm applies a force in a direction in which the nip pressure decreases.

12 . The secondary transfer device according to claim 11 ,
wherein a distance from the rotation fulcrum to the working point is longer than a distance from the force point of the depressurization arm to the rotation fulcrum.

13 . The secondary transfer device according to claim 1 ,
wherein the first drive and the second drive are disposed so that projected images when projected in an axial direction of the secondary transfer roller overlap.

14 . The secondary transfer device according to claim 2 ,
wherein the pressing arm pushes the secondary transfer roller toward the pressing position through the spring and the depressurization arm in this order, and the high-speed depressurization mechanism performs the depressurization by pushing the spring back to the pressing arm side with the depressurization arm.

15 . The secondary transfer device according to claim 2 ,
wherein the depressurization cam includes a slope and a flat part on an outer periphery as a region where a depressurization state is formed, and the slope and the flat part are properly used depending on a length of time to maintain depressurization.

16 . The secondary transfer device according to claim 1 ,
wherein the secondary transfer roller is provided in a secondary transfer unit, and the pressure-releasing mechanism and the high-speed depressurization mechanism displace the secondary transfer unit.

17 . The secondary transfer device according to claim 16 ,
wherein the pressure-releasing mechanism and the high-speed depressurization mechanism are provided below the secondary transfer unit.

18 . The secondary transfer device according to claim 2 ,
wherein the rotation shaft of the pressing cam can be moved in an axial direction when a lock mechanism is released, and the movement releases engagement between the pressing cam and an abutting member on the pressing arm side, or the rotation shaft of the depressurization cam can be moved in the axial direction when the lock mechanism is released, and the movement releases the engagement between the depressurization cam and the abutting member on the depressurization arm side.

19 . The secondary transfer device according to claim 3 ,
wherein, when the predetermined lock mechanism is released, the rotation shaft of the pressing cam and the rotation shaft of the depressurization cam can be simultaneously moved in the axial direction, and the mov

Assignees

• Konica Minolta Inc

Inventors

• Ui Hiroyuki
• Tanaka Kenichi

Classifications

• G03G2221/1654

  Locks and means for positioning or alignment · CPC title

• G03G15/0131 Primary

  for transferring a pattern to a second base · CPC title

• G03G2215/00139

  Belt · CPC title

• G03G15/167

  at least one of the recording member or the transfer member being rotatable during the transfer · CPC title

• G03G15/1615 Primary

  relating to the driving mechanism for the intermediate support, e.g. gears, couplings, belt tensioning · CPC title