IMAGE FORMING APPARATUS

• US 20160187819A1
• Filed: 03/09/2016
• Published: 06/30/2016
• Est. Priority Date: 09/13/2013
• Status: Active Grant

• Current Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Original Assignee: Canon Ayutthaya Limited (Canon Inc.)
• Inventors: Tajiri, Tsuyoshi, Ishikawa, Rin
• Granted Patent: US 9,720,352 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: G03G 15/0189 primary transfer to an intermediate transfer belt G03G15/0184 takes precedence
• CPC Class Codes: G03G 15/1615 relating to the driving mechanism for the intermediate support, e.g. gears, couplings, belt tensioning
• CPC Class Codes: G03G 15/5058 using a test patch

Abstract

To provide an image forming apparatus capable of easily suppressing a variation of an inclination of a sensor relative to an endless belt and the capable of high accuracy and stabilized sensing operation.

An image forming apparatus (100) includes a belt unit (200) having an endless belt supported to be rotatable in a circumferential direction (R), an image forming unit (1Y, 1M, 1C, 1Bk) for forming an image on the belt unit, and an optical sensor (31) for detecting light projected onto the endless belt. The image forming apparatus further comprises a sensor supporting member (32) for supporting the sensor, and a positioning portion (400, 500) including, as a unit, a first positioning portion (400a, 500a) for positioning the belt unit by being contacted by the belt unit and a second positioning portion (401a, 501a, 501b) positioning the sensor supporting member by being contacted by the sensor supporting member.

Claims

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;

a positioning member including, at each of end portions of said belt with respect to a widthwise direction crossing with a moving direction of said belt, a first portion-to-be-contacted contacting said belt unit at a plurality of positioning places and a second portion-to-be-contacted contacting said sensor unit at a plurality of positioning places.

2. An apparatus according to claim 1, wherein said positioning member is disposed at each of 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 sensor supporting member is positioned by contacting said positioning member.

4. An apparatus according to claim 1, wherein said belt unit including 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 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, further comprising an openable and closable door member, wherein said belt unit is detachably mountable relative to the main assembly in a state that said door member is opened.

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 a main assembly of said apparatus substantially in a 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, and said sensor unit is disposed in a side of said door member with respect to said positioning member.

9. An apparatus according to claim 6, wherein said sensor unit is movable when said belt unit is mounted and dismounted, 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 a main assembly of the apparatus.

10. An apparatus according to claim 6, wherein said urging member urges said sensor unit toward said positioning member and toward a supporting portion supporting said first stretching roller.

11. An apparatus according to claim 6, wherein said plurality of stretching rollers includes a second stretching roller provided adjacent to a downstream side of first stretching roller with respect to the moving direction of said belt, and said second stretching roller is a driving roller configured to apply a driving force to said belt.

12. An apparatus according to claim 11, wherein said second stretching roller has a diameter smaller than a diameter of said first stretching roller.