Development device and image formation apparatus
View Patent ↗A development device includes an image carrier configured to develop an electrostatic latent image by using a developer, a development member configured to supply the developer to the image carrier, a developer supply member configured to supply the developer onto a surface of the development member, and a developer restriction member including a contact portion configured to form a developer layer on the surface of the development member while being in contact with the surface. A curvature radius R [mm] of the contact portion of the developer restriction member is 0.17 [mm] to 0.28 [mm], both inclusive, and an ASKER F hardness [°] of the developer supply member is 181.82×R+9.09≦F≦−250×R+130.
1. A development device comprising:
an image carrier configured to develop an electrostatic latent image by using a developer;
a development member configured to supply the developer to the image carrier;
a developer supply member configured to supply the developer onto a surface of the development member; and
a developer restriction member including a contact portion configured to form a developer layer on the surface of the development member while being in contact with the surface, wherein
a curvature radius R [mm] of the contact portion of the developer restriction member is 0.17 [mm] to 0.28 [mm], both inclusive, and
an ASKER F hardness [°] of the developer supply member is
181.82 ×R+ 9.09 ≦F≦− 250 ×R+ 130,
wherein
the developer supply member has an almost columnar shape, and
the developer supply member satisfies 0.962≦L 1 /L 2 ≦1,
where L 1 is an outer diameter of the developer supply member in an portion near an end in a longitudinal direction, and L 2 is an outer diameter thereof in a center portion in the longitudinal direction.
2. The development device according to claim 1 , wherein the ASKER F hardness [°] of the developer supply member is
181.82 ×R+ 9.09+5×( L 1 /L 2−0.975)/0.013 ≦F≦− 250 ×R+ 130+5×(0.975 −L 1 /L 2)/0.013.
3. The development device according to claim 1 , wherein
the developer supply member is configured to supply the developer to the development member when a predetermined bias voltage is applied thereto, and
the development device is provided with a voltage control member configured to control the bias voltage in accordance with a temperature C [C.°] of a print environment.
4. The development device according to claim 3 ,
wherein the voltage control member controls an applied correction voltage value, D [V], of the bias voltage applied to the developer supply member in accordance with the temperature C[C.°] of the print environment, in such a way that
D [V]=0, when C [C.°]<20 [C.°],
D [V]=−2.5 [V]× C [C.°]+40 [V], when 20 [C.°]≦ C [C.°]<36 [C.°],
D [V]=−50 [V], when C [° C.]≧36 [° C.].
5. The development device according to claim 1 , wherein the developer supply member is a supply roller configured to rotate in contact with the development member and to supply the developer to the development member.
6. The development device according to claim 5 , wherein the supply roller is a sponge roller.
7. The development device according to claim 6 , wherein the sponge roller includes a first metal core portion being a conductive shaft and a conductive foam layer formed around the first metal core portion.
8. The development device according to claim 7 , wherein the foam layer is made of a silicone rubber.
9. The development device according to claim 1 , wherein the development member is a development roller facing the image carrier and configured to supply the developer supplied from a supply roller to the image carrier.
10. The development device according to claim 9 , wherein the development roller includes a second metal core portion being a conductive shaft, an elastic layer formed around the second metal core portion, and a process layer formed on a surface of the elastic layer and processed to be electrifiable and to have a certain roughness.
11. The development device according to claim 10 , wherein the elastic layer is made of a polyurethane rubber.
12. The development device according to claim 1 , wherein a partial resistance value A [log Ω] of the developer supply member is 6.00 [log Ω] to 8.00 [log Ω], both inclusive.
13. The development device according to claim 12 , wherein the ASKER F hardness [°] of the developer supply member is
181.82 ×R+ 9.09+5×(7 −A )≦ F≦− 250 ×R+ 130+5×( A− 7).
14. The development device according to claim 1 , wherein the developer restriction member is a development blade formed by bending an elastic plate material into an almost L-shape.
15. The development device according to claim 1 , wherein the developer restriction member is a development blade having one end fixed and the other end bent into an almost L-shape.
16. An image formation apparatus comprising:
the development device of claim 1 ;
a conveyance mechanism configured to convey a record medium;
a transfer portion configured to transfer the developer visualized by the development device to the record medium; and
a fuse portion configured to fuse the developer transferred to the record medium.
17. A development device comprising:
an image carrier configured to develop an electrostatic latent image by using a developer;
a development member configured to supply the developer to the image carrier;
a developer supply member configured to supply the developer onto a surface of the development member; and
a developer restriction member including a contact portion configured to form a developer layer on the surface of the development member while being in contact with the surface, wherein
a curvature radius R [mm] of the contact portion of the developer restriction member is 0.17 [mm] to 0.28 [mm], both inclusive, and
an ASKER F hardness [°] of the developer supply member is
181.82 ×R+ 9.09 ≦F≦− 250 ×R+ 130,
wherein a partial resistance value A [log Ω] of the developer supply member is 6.00 [log Ω] to 8.00 [log Ω], both inclusive.
18. The development device according to claim 17 , wherein the ASKER F hardness [°] of the developer supply member is
181.82 ×R+ 9.09+5×(7 −A )≦ F≦− 250 ×R+ 130+5×( A− 7).
19. The development device according to claim 17 , wherein
the developer supply member is configured to supply the developer to the development member when a predetermined bias voltage is applied thereto, and
the development device is provided with a voltage control member configured to control the bias voltage in accordance with a temperature C [C.°] of a print environment.
20. The development device according to claim 19 ,
wherein the voltage control member controls an applied correction voltage value, D [V], of the bias voltage applied to the developer supply member in accordance with the temperature C[C.°] of the print environment, in such a way that
D [V]=0, when C [C.°]<20 [C.°],
D [V]=−2.5 [V]× C [C.°]+40 [V], when 20 [C.°]≦ C [C.°]<36 [C.°],
D [V]=−50 [V], when C [° C.]≧36 [° C.].
21. The development device according to claim 17 , wherein the ASKER F hardness [°] of the developer supply member is
181.82 ×R+ 9.09+5×( L 1 /L 2−0.975)/0.013 ≦F≦− 250 ×R+ 130+5×(0.975 −L 1 /L 2)/0.03,
where L 1 is an outer diameter of the developer supply member in an portion near an end in a longitudinal direction, and L 2 is an outer diameter thereof in a center portion in the longitudinal direction.
22. The development device according to claim 17 , wherein the developer supply member is a supply roller configured to rotate in contact with the development member and to supply the developer to the development member.
23. The development device according to claim 22 , wherein the supply roller is a sponge roller.
24. The development device according to claim 23 , wherein the sponge roller includes a first metal core portion being a conductive shaft and a conductive foam layer formed around the first metal core portion.
25. The development device according to claim 24 , wherein the foam layer is made of a silicone rubber.
26. The development device according to claim 17 , wherein the development member is a development roller facing the image carrier and configured to supply the developer supplied from a supply roller to the image carrier.
27. The development device according to claim 26 , wherein the development roller includes a second metal core portion being a conductive shaft, an elastic layer formed around the second metal core portion, and a process layer formed on a surface of the elastic layer and processed to be electrifiable and to have a certain roughness.
28. The development device according to claim 27 , wherein the elastic layer is made of a polyurethane rubber.
29. The development device according to claim 17 , wherein the developer restriction member is a development blade formed by bending an elastic plate material into an almost L-shape.
30. The development device according to claim 17 , wherein the developer restriction member is a development blade having one end fixed and the other end bent into an almost L-shape.
31. An image formation apparatus comprising:
the development device of claim 17 ;
a conveyance mechanism configured to convey a record medium;
a transfer portion configured to transfer the developer visualized by the development device to the record medium; and
a fuse portion configured to fuse the developer transferred to the record medium.
32. The development device according to claim 17 , wherein the development supply member comprises a supply roller that has a crown shape.