Image forming apparatus with accurate positioning of sensor unit

Patent metadata

Field	Value
Publication number	US-9720352-B2
Application number	US-201615065063-A
Country	US
Kind code	B2
Filing date	Mar 9, 2016
Priority date	Sep 13, 2013
Publication date	Aug 1, 2017
Grant date	Aug 1, 2017

Abstract

An image forming apparatus is designed to be capable of easily suppressing a variation of an inclination of a sensor relative to an endless belt and capable of high accuracy and stabilized sensing operation. The image forming apparatus includes a belt unit having an endless belt supported to be rotatable in a circumferential direction, an image forming unit for forming an image on the belt unit, and an optical sensor for detecting light projected onto the endless belt. The image forming apparatus further includes a sensor supporting member for supporting the sensor, and a positioning portion including, as a unit, a first positioning portion for positioning the belt unit by being contacted by the belt unit and a second positioning portion positioning the sensor supporting member by being contacted by the sensor supporting member.

First claim

The invention claimed is:

1. An image forming apparatus comprising:
a belt unit including an endless belt capable of traveling around a plurality of stretching rollers supporting said endless belt;
an image forming unit configured to form a toner image on said belt;
a sensor unit including a sensor including a light emitting portion and a light receiving portion and configured to detect light from said belt;
a setting portion configured to set an image forming condition of said image forming unit in accordance with an output of said sensor; and
a positioning member including a first portion-to-be-contacted contacting at least one end portion of said belt unit with respect to a widthwise direction crossing with a moving direction of said belt at a plurality of positioning places and a second portion-to-be-contacted contacting at least one end portion of said sensor unit with respect to the widthwise direction at a plurality of positioning places.

2. An apparatus according to claim 1 , wherein said positioning member is disposed at each of the end portions with respect to the widthwise direction.

3. An apparatus according to claim 1 , further comprising a supporting member extending in the widthwise direction to support said sensor, wherein said supporting member is positioned by contacting said positioning member.

4. An apparatus according to claim 1 , wherein said belt unit includes a stretching roller supporting member for supporting said plurality of stretching rollers, and said stretching roller supporting member is positioned by contacting said positioning member.

5. An apparatus according to claim 1 , wherein the light from said light emitting portion is projected onto a flat surface portion of said belt adjacent a first stretching roller of said plurality of stretching rollers, and a plane including a line connecting said light emitting portion and said light receiving portion and a position of said belt where the light is projected is perpendicular to the flat surface portion.

6. An apparatus according to claim 1 , wherein said belt unit is detachably mountable relative to a main assembly of said apparatus.

7. An apparatus according to claim 6 , wherein the positioning places of said first portion-to-be-contacted are arranged substantially in a horizontal direction, and said belt unit is mounted and dismounted relative to the main assembly of said apparatus substantially in the horizontal direction.

8. An apparatus according to claim 6 , wherein the positioning places of said second portion-to-be-contacted are arranged substantially in a vertical direction.

9. An apparatus according to claim 6 , wherein said sensor unit is movable, and wherein said apparatus further comprises an urging member for urging said sensor unit toward said positioning member in a state that said belt unit is mounted to the main assembly of said apparatus.

10. An apparatus according to claim 9 , wherein said urging member urges said sensor unit toward said positioning member and toward a supporting portion supporting a first stretching roller of said plurality of stretching rollers.

11. An image forming apparatus comprising:
a belt unit, including an endless belt, a plurality of stretching rollers, and a stretching roller supporting member, said belt unit being detachably mountable relative to a main assembly of said apparatus, the belt being capable of traveling around the stretching rollers, the stretching rollers, including an opposing roller, supporting the endless belt, the stretching roller supporting member, including a first contacting portion and a third portion-to-be-contacted, to support the plurality of stretching rollers, the third portion-to-be-contacted being disposed where the opposing roller is supported, as viewed in a direction of a rotational axis of the opposing roller;
an image forming unit configured to form a toner image on the belt;
a sensor unit including a sensor and a sensor supporting member, the sensor including a light emitting portion and a light receiving portion to detect light from the belt adjacent to the opposing roller, the sensor supporting member including a second contacting portion and a third contacting portion to support the sensor so as to be movable in the main assembly;
a controller configured to control an image forming condition of said image forming unit in accordance with an output of the sensor;
a positioning member, including a first portion-to-be-contacted and a second portion-to-be-contacted, configured to position the stretching roller supporting member and the sensor supporting member, the first portion-to-be-contacted being contactable to the first contacting portion, and the second portion-to-be-contacted being contactable to the second contacting portion; and
an urging member configured to urge the sensor supporting member toward the third portion-to-be-contacted and the second portion-to-be-contacted in a state that said belt unit is mounted to the main assembly and the first contacting portion contacts the first portion-to-be-contacted, so that the third contacting portion contacts the third portion-to-be-contacted and the second contacting portion contacts the second portion-to-be-contacted.

12. An apparatus according to claim 11 , wherein said positioning member is disposed at each of end portions with respect to a widthwise direction crossing with a moving direction of the belt.

13. An apparatus according to claim 11 , wherein the first contacting portion contacts the first portion-to-be-contacted at plural positions.

14. An apparatus according to claim 13 , wherein the second contacting portion contacts the second portion-to-be-contacted at plural positions.

15. An apparatus according to claim 11 , wherein the first portion-to-be-contacted determines a position of the stretching roller supporting member in a first direction, and the second portion-to-be-contacted determines a position of the sensor supporting member in a second direction crossing with the first direction.

16. An apparatus according to claim 15 , wherein the first direction is substantially a vertical direction, and said belt unit is mounted and dismounted relative to the main assembly substantially in a horizontal direction.

17. An apparatus according to claim 15 , wherein the third contacting portion determines a position of the stretching roller supporting member by contacting the third portion-to-be-contacted.

18. An apparatus according to claim 15 , wherein as viewed in the direction of the rotational axis of the opposing roller, a length of said positioning member along the second direction is longer than a length of said positioning member along the first direction.

Assignees

• Canon Kk

Inventors

• Tajiri Tsuyoshi
• Ishikawa Rin

Classifications

• G03G15/5058

  using a test patch · CPC title

• G03G15/1615 Primary

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

• G03G15/0189 Primary

  primary transfer to an intermediate transfer belt (G03G15/0184 takes precedence) · CPC title