Image forming device and developing device

1. A developing device that is provided in an image forming device that holds developer and forms an image, comprising:

an image carrier on which an electrostatic latent image is formed;

a developer carrier that is configured to form a developer image on a surface of the image carrier by urging the developer on the electrostatic latent image; and

a contact member that is configured to contact the developer carrier and that includes a bent part at a tip part thereof, the bent part contacting the developer carrier, wherein

the contact member contacts the developer carrier and exerts a contact pressure per unit area thereon, the contact pressure per unit area being based on charging characteristics of the developer being used and a bent ratio of the bent part,

the developing device comprises a plurality of developing devices,

each of the plurality of developing devices contains one of at least two types of developers each having different charging characteristics, and

a bent ratio of a first bent part of a first one of the developing devices that uses more easily charged developer is set smaller than a bent ratio of a second bent part of a second one of the developing devices that uses more difficultly charged developer.

2. An image forming device, comprising:

the developing device according to claim 1 ;

a transfer part that is configured to transfer the developer image onto a medium; and

a fusing part that is configured to fuse the developer image transferred onto the medium by the transfer part.

3. The image forming device according to claim 2 , wherein

each of the plurality of the developing devices includes a supplying member that supplies the developer to a corresponding developer carrier, and

deformation amounts between the corresponding developer carriers and supplying members individually vary corresponding to respective distances from the fusing part, the deformation amounts corresponding to contact strengths indicating a degree of contact between an elastic layer of the developer carrier and an elastic layer of the supplying member.

4. The image forming device according to claim 2 , wherein

a first deformation amount of a first one of the developing devices that is most closely positioned to the fusing part is larger than a second deformation amount of a second one of the developing devices that is most distantly positioned from the fusing part.

5. The developing device according to claim 1 , wherein

the contact member is configured to regulate a layer thickness of the developer supplied on the developer carrier.

6. The developing device according to claim 1 , wherein

the bent ratio of the contact member is predetermined based on the charging characteristics of the developer being used.

7. The developing device according to claim 6 , wherein

the contact member with a high bent ratio is used when the developer has easily charged characteristics, and

the contact member with a low bent ratio is used when the developer has difficultly charged characteristics.

8. A plurality of developing devices that are provided in an image forming device that holds developer and forms an image, each comprising:

an image carrier on which an electrostatic latent image is formed;

a developer carrier that is configured to form a developer image on a surface of the image carrier by urging the developer on the electrostatic latent image; and

a contact member that is configured to contact the developer carrier and to regulate a layer thickness of the developer supplied on the developer carrier, the contact member including a bent part at a tip part thereof, the bent part contacting the developer carrier, wherein

each of the plurality of developing devices contains one of at least two types of developers each having different charging characteristics,

the contact member contacts the developer carrier and exerts a contact pressure per unit area thereon, the contact pressure per unit area being based on charging characteristics of the developer being used and a bent ratio of the bent part, and

a bent ratio of a bent part of a first one of the developing devices containing more easily charged developer is smaller than a bent ratio of a bent part of a second one of the developing devices containing more difficultly charged developer.

9. The developing devices according to claim 8 , each further comprising:

a supplying member that supplies the developer to the developer carrier, wherein

deformation amounts between the corresponding developer carrier and supplying member individually vary corresponding to locations where the respective developing devices are provided in the image forming device, the deformation amounts corresponding to a contact strength indicating a degree of contact between an elastic layer of the developer carrier and an elastic layer of the supplying member.

10. The developing devices according to claim 9 , wherein

a deformation amount of a third one of the developing devices positioned more closely to the fusing part is set larger than a deformation amount of a fourth one of the developing devices positioned more distantly from the fusing part.

11. An image forming device, comprising:

the developing devices according to claim 8 ;

a transfer part that transfers the developer image onto a medium; and

a fusing part that fuses the developer image transferred onto the medium by the transfer part.

12. An image forming device, comprising:

a first developing device including a first developer carrier that is configured to supply a first developer to a first image carrier, and a first contact member including a first bent part at a tip part thereof that is configured to contact the first developer carrier, the first developer having first characteristics; and

a second developing device including a second developer carrier that is configured to supply a second developer to a second image carrier, and a second contact member including a second bent part at a tip part thereof that is configured to contact the second developer carrier, the second developer having second characteristics, wherein

the first bent part has a first radius of curvature,

the second bent part has a second radius of curvature,

a first contact pressure per unit area of the first contact member is determined based on a bent ratio of the first bent part, and

a second contact pressure per unit area of the second contact member is determined based on a bent ratio of the second bent part.

13. The image forming device according to claim 12 , wherein

the first developer is more easily charged than the second developer, and

the first radius of curvature of the first bent part of the developing device is set smaller than the second radius of curvature of the second bent part of the second developing device.

14. The image forming device according to claim 12 , wherein

the first developer is more easily charged than the second developer, and

the bent ratio of the first bent part of the developing device is set smaller than the bent ratio of the second bent part of the second developing device.

15. The image forming device according to claim 12 , wherein

the first and second contact members are configured to regulate a layer thickness of the first and second developers supplied on the first and second developer carriers, respectively.

16. An image forming device, comprising:

a developing device that holds developer and forms an image, the developing device including:

an image carrier on which an electrostatic latent image is formed;

a developer carrier that is configured to form a developer image on a surface of the image carrier by urging the developer on the electrostatic latent image; and

a contact member that is configured to contact the developer carrier and that includes a bent part at a tip part thereof, the bent part contacting the developer carrier;

a transfer part that is configured to transfer the developer image onto a medium; and

a fusing part that is configured to fuse the developer image transferred onto the medium by the transfer part, wherein

the contact member contacts the developer carrier and exerts a contact pressure per unit area thereon, the contact pressure per unit area being based on charging characteristics of the developer being used and a bent ratio of the bent part,

the developing device comprises a plurality of developing devices,

each of the plurality of developing devices contains one of at least two types of developers each having different charging characteristics,

each of the plurality of the developing devices includes a supplying member that supplies the developer to a corresponding developer carrier, and

deformation amounts between the corresponding developer carriers and supplying members individually vary corresponding to respective distances from the fusing part, the deformation amounts corresponding to contact strengths indicating a degree of contact between an elastic layer of the developer carrier and an elastic layer of the supplying member.