Photosensitive member unit, cartridge and electrophotographic image forming apparatus
A photosensitive member unit is detachably mountable to a main assembly of an image forming apparatus. The photosensitive member unit includes a photosensitive member rotatable about a rotational axis thereof, a rotatable first helical gear portion; and a second helical gear portion integrally rotatable with the first helical gear portion. A twisting direction of a tooth of the second helical gear portion is the same as a twisting direction of a tooth of the first helical gear portion, and a helix angle of the tooth of the second helical gear portion is greater than a helix angle of the tooth of the first helical gear portion.
1 . A photosensitive member unit detachably mountable to a main assembly of an image forming apparatus, the photosensitive member unit comprising:
a photosensitive member rotatable about a rotational axis thereof;
a rotatable first helical gear portion; and
a second helical gear portion integrally rotatable with the first helical gear portion, the second helical gear portion being provided between the photosensitive member and the first helical gear portion in a direction of the rotational axis of the photosensitive member,
wherein a twisting direction of a tooth of the second helical gear portion is the same as a twisting direction of a tooth of the first helical gear portion, and a helix angle of the tooth of the second helical gear portion is greater than a helix angle of the tooth of the first helical gear portion.
2 . A photosensitive member unit according to claim 1 , wherein with respect to the rotational axis of the photosensitive member, a gap is formed between the first helical gear portion and the second helical gear portion.
3 . A photosensitive member unit according to claim 2 , further comprising an intermediary member provided between the first helical gear portion and the second helical gear portion with respect to the rotational axis of the photosensitive member, the intermediary member being capable of filling the gap.
4 . A photosensitive member unit according to claim 3 , wherein the intermediary member is movable between a position for providing the gap and a position for filling the gap, by rotation thereof.
5 . A photosensitive member unit according to claim 3 , wherein the intermediary member is movable between a position for providing the gap and a position for filling the gap, by movement thereof in a direction perpendicular to the rotational axis of the photosensitive member.
6 . A photosensitive member unit according to claim 3 , wherein the intermediary member is made of an elastic member and is capable of taking a position for providing the gap and a position for filling the gap, by elastic deformation thereof,
with respect to the rotational axis of the photosensitive member, a tooth width Wc of the first helical gear portion and a width We of the gap satisfy:
Wc>We≥Wc/ 5.
7 . A photosensitive member unit according to claim 2 , wherein with respect to the rotational axis of the photosensitive member, a tooth width Wc of the first helical gear portion and a width We a gap satisfy: Wc>We ≥Wc/5.
8 . A photosensitive member unit according to claim 7 , wherein with respect to the rotational axis of the photosensitive member, the width We and a tooth width Wd of the second helical gear portion satisfy:
Wd>We.
9 . A photosensitive member unit according to claim 1 , wherein the first helical gear portion and the second helical gear portion each have at least one tooth having a width satisfying:
Wc>Wd,
where Wc is a tooth width of the first helical gear portion, and Wd is a tooth width of the second helical gear portion, measured in the direction of the rotational axis of the photosensitive member.
10 . A photosensitive member unit according to claim 9 , wherein a tooth width Wc1 of the tooth of the first helical gear portion that has a largest tooth width measured in the direction of the rotational axis of the photosensitive member and a tooth width Wd1 of the tooth of the second helical gear portion that has a largest tooth width measured in the direction of the rotational axis of the photosensitive member satisfy:
Wd 1≤(4/5)· Wc 1.
11 . A photosensitive member unit according to claim 9 , wherein a tooth width Wc1 of the tooth of the first helical gear portion that has a largest tooth width measured in the direction of the rotational axis of the photosensitive member and a tooth width Wd1 of the tooth of the second helical gear portion that has a largest tooth width measured in the direction of the rotational axis of the photosensitive member satisfy:
Wd 1≤(3/4)· Wc 1.
12 . A photosensitive member unit according to claim 11 , wherein the tooth width Wc1 satisfy:
Wd 1≥(1/10)· Wc 1.
13 . A photosensitive member unit according to claim 1 , wherein the helix angle of the tooth of the first helical gear portion is not less than 15° and not more than 40°.
14 . A photosensitive member unit according to claim 1 , wherein the helix angle of the tooth of the first helical gear portion is not less than 20° and not more than 35°.
15 . A photosensitive member unit according to claim 1 , wherein he helix angle of the tooth of the second helical gear portion is not less than 20° and not more than 40°.
16 . A photosensitive member unit according to claim 1 , wherein the helix angle of the tooth of the second helical gear portion is not less than 25° and not more than 35°.
17 . A photosensitive member unit according to claim 1 , wherein the first helical gear portion includes a plurality of such teeth, at least one of which is constituted by a plurality of first projections provided separately in the direction of the rotational axis of the photosensitive member or in a rotational movement direction of the first helical gear portion.
18 . A photosensitive member unit according to claim 1 , wherein the second helical gear portion includes a plurality of such teeth, at least one of which is constituted by a plurality of second projections provided separately in the direction of the rotational axis of the photosensitive member or in a rotational movement direction of the second helical gear portion.
19 . A photosensitive member unit according to claim 1 , wherein the first helical gear portion and the second helical gear portion include the same number of teeth.
20 . A photosensitive member unit according to claim 1 , wherein the first helical gear portion includes a tooth missing part.
21 . A photosensitive member unit according to claim 1 , wherein the second helical gear portion includes a tooth missing part.
22 . A photosensitive member unit according to claim 1 , wherein a projecting direction of the first helical gear portion and a projecting direction of the second helical gear portion include respective components parallel with the rotational axis of the photosensitive member.
23 . A photosensitive member unit according to claim 1 , further comprising an elastic member covering the first helical gear portion and/or the second helical gear portion.
24 . A photosensitive member unit according to claim 1 , wherein while the first helical gear portion and the second helical gear portion are rotated in a predetermined direction, the first helical gear portion and the second helical gear portion are in a state that the tooth of the second helical gear portion is fixed so as not to be rotated in a direction opposite to the predetermined direction relative to the first helical gear portion.
25 . A photosensitive member unit according to claim 1 , wherein the first helical gear portion is capable of transmitting a driving force to the second helical gear portion.
26 . A photosensitive member unit according to claim 1 , wherein the first helical gear portion and the second helical gear portion are rotatable coaxially with each other.
27 . A photosensitive member unit according to claim 26 , wherein a rotational axis of the first helical gear portion and a rotational axis of the second helical gear portion is coaxial with the rotational axis of the photosensitive member.
28 . A photosensitive member unit according to claim 26 , wherein the first helical gear portion and the second helical gear portion are integrally molded.
29 . A photosensitive member unit according to claim 28 , wherein the first helical gear portion and the second helical gear portion are integrally resin-molded.
30 . A photosensitive member unit according to claim 26 , wherein a diameter of an addendum circle of the second helical gear portion is greater than a diameter of a dedendum circle of the first helical gear portion or 0 . 8 times the diameter of the addendum circle of the first helical gear portion, and less than 1.1 times the diameter of the addendum circle of the first helical gear portion.
31 . A photosensitive member unit according to claim 30 , wherein the diameter of the addendum circle of the second helical gear portion is greater than 0.9 times the diameter of the addendum circle of the first helical gear portion.
32 . A photosensitive member unit according to claim 1 , wherein a rotational axis of the first helical gear portion and a rotational axis of the second helical gear portion are not coaxial with each other.
33 . A photosensitive member unit according to claim 32 , wherein the rotational axis of the first helical gear portion or the rotational axis of the second helical gear portion is coaxial with the rotational axis of the photosensitive member.
34 . A photosensitive member unit according to claim 32 , wherein the rotational axis of the first helical gear portion and the rotational axis of the second helical gear portion are parallel to each other.
35 . A photosensitive member unit according to claim 1 , wherein the first helical gear portion, the second helical gear portion, or the first helical gear portion and the second helical gear portion are provided on a belt-like member.
36 . A photosensitive member unit according to claim 1 , wherein the first helical gear portion is connected with the second helical gear portion so as to be capable of transmitting a driving force.
37 . A photosensitive member unit according to claim 36 , wherein the first helical gear portion is connected with the second helical gear portion with play in a rotational movement direction of the first helical gear portion.
38 . A photosensitive member unit according to claim 36 , wherein the first helical gear portion is capable of being in a connected state of being connected with the second helical gear portion to transit the driving force thereto and in a disconnected state of being incapable of transmitting the driving force to the second helical gear portion.
39 . A photosensitive member unit according to claim 1 , wherein the first helical gear portion is connected with the photosensitive member so as to be capable of transmitting a rotational force.
40 . A photosensitive member unit according to claim 1 , further comprising a flange mounted to an end of the photosensitive member in the direction of the rotational axis of the photosensitive member,
wherein the first helical gear portion and the second helical gear portion are provided on the flange.
41 . A photosensitive member unit according to claim 1 , further comprising a third gear portion connected so as to be capable of transmitting a driving force to the photosensitive member.