Transfer device and attachment of the transfer device to a cover of an image forming apparatus

1. An image forming apparatus, comprising:

a main body;

a cover configured to be provided so as to be capable of being opened and closed with respect to the main body;

an attachment unit configured to be provided on the cover;

a unit configured to be attached to the attachment unit;

a positioning member configured to, on closing of the cover, position the unit with respect to a member attached to the main body or the main body;

a guiding member configured to guide the unit to the positioning member;

a protrusion configured to be provided at the guiding member to protrude in an attaching direction of the unit; and

a lock member at which the unit attached to the attachment unit is hooked and locked on a hook of the attachment unit.

2. The image forming apparatus according to claim 1 , wherein the protrusion is provided between a start point at which, when the cover is closed, the unit starts to abut the main body or the member attached to the main body, and the positioning member.

3. The image forming apparatus according to claim 1 , wherein the protrusion includes a guide surface exerting a force on the unit, upon abutment with the unit, to allow the unit to be able to be attached to the attachment unit.

4. The image forming apparatus according to claim 3 , wherein

the protrusion includes a first guide surface provided upstream of a direction of guiding the unit to the positioning member and a second guide surface provided downstream of the first guide surface and is set at an angle different from that of the first guide surface, and

at least the second guide surface is set at an angle at which a force acts on the unit to allow the unit to be able to be attached to the attachment unit upon abutment with the unit.

5. The image forming apparatus according to claim 1 , wherein an abutment force with which the unit abuts the guiding member acts in a direction inclined toward the positioning member with respect to a direction orthogonal to the guiding member.

6. The image forming apparatus according to claim 5 , wherein, when it is assumed that an angle formed by the direction of the abutment force with which the unit abuts the guiding member and the direction orthogonal to the guiding member is designated as θ and the friction coefficient between the unit and the guiding member is designated as μ, tan θ>μis held.

7. The image forming apparatus according to claim 6 , wherein

the unit is configured to be displaceable with respect to the cover, and

when the cover is closed, the unit is displaced by abutment with the guiding member to increase the angle θ.

8. The image forming apparatus according to claim 5 , wherein

the cover is provided with an elastic member to bias the unit toward the positioning member and the guiding member, and

a movement locus of the unit abutment member abutting the guiding member and guided to the positioning member and a movement locus of the cover being closed, come closer to each other in the direction of closing the cover.

9. The image forming apparatus according to claim 1 , wherein the unit comprises

an insertion member that is inserted into an insertion hole provided in the attachment unit.

10. The image forming apparatus according to claim 1 , further comprising an elastic member configured to press the unit toward the positioning member and the guiding member, wherein

the attaching direction of the unit and the pressing direction of the elastic member when positioning the unit at the positioning member intersect each other.

11. An image forming apparatus, comprising:

a main body including a frame;

a cover including a hole and configured to be opened and closed with respect to the main body;

a transfer roller supporter including a pin and configured to support a transfer roller and to be attached to the cover by inserting the pin into the hole in an attaching direction;

a groove provided on the frame and configured to, on closing of the cover, position a shaft of the transfer roller with respect to the frame;

a guide provided on the frame and configured to guide the shaft of the transfer roller to the groove; and

a protrusion provided on the guide and protruding in the attaching direction.

12. The image forming apparatus according to claim 11 , wherein the transfer roller supporter includes a claw and the cover includes a hook on which the claw is hooked when the pin is inserted into the hole.

13. A transfer device, comprising:

a transfer unit configured to transfer an image to a recording medium;

a transfer entrance guide configured to be switchable between a guiding position at which to guide the recording medium to the transfer unit and an evacuation position being relatively evacuated from the guiding position;

a supporting member that supports the transfer entrance guide in a displaceable manner;

a guide positioning member configured to guide the transfer entrance guide at the guiding position; and

a guide guiding member configured to guide the transfer entrance guide to the guide positioning member, wherein

the transfer device further comprises a guiding auxiliary member, when the transfer entrance guide is guided to the guide positioning member along the guide guiding member, abuts an abutment member of the transfer entrance guide and presses the transfer entrance guide in a guiding direction toward the guide positioning member.

14. The transfer device according to claim 13 , wherein an elastic member is provided to bias the transfer entrance guide toward a guide surface of the guide guiding member.

15. The transfer device according to claim 14 , wherein the transfer entrance guide is provided with a stopper that abuts another member different from the transfer entrance guide to control displacement of the transfer entrance guide against a biasing force of the elastic member and hold the transfer entrance guide at a position capable of guiding the transfer entrance guide by the guide guiding member.

16. The transfer device according to claim 15 , wherein, while the stopper is in abutment with the other member to control displacement of the transfer entrance guide, the transfer entrance guide is rotated around the stopper by the biasing force of the elastic member to bring the abutment member into abutment with the guiding auxiliary member.

17. The transfer device according to claim 13 , wherein, while the transfer entrance guide is positioned by the guide positioning member, the guiding auxiliary member is in non-contact with the abutment member of the transfer entrance guide.

18. The transfer device according to claim 13 , wherein

the supporting member is provided with one of transfer members in a pair constituting the transfer unit by abutment with each other, and

while the guiding auxiliary member and the abutment member are in abutment with each other, the transfer entrance guide is in non-contact with the transfer member.

19. The transfer device according to claim 18 , wherein

the transfer member is a transfer roller rotatably supported by the supporting member via a shaft bearing, and

the guiding auxiliary member is a shaft bearing for the transfer roller.

20. The transfer device according to claim 18 , wherein

the transfer member is a transfer roller rotatably supported by the supporting member via a shaft bearing, and

the guiding auxiliary member is a rotating shaft of the transfer roller.

21. The image forming apparatus according to claim 1 , wherein the unit is removable from the attachment unit.