Image forming apparatus using a contact or a proximity type of charging system

• US 20040213600A1
• Filed: 02/03/2004
• Published: 10/28/2004
• Est. Priority Date: 02/18/2003
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Ohshima, Kohichi, Watanabe, Kazuhito, Suzuki, Yasuo, Shakuto, Masahiko, Watanabe, Kazuhiko, Sugiura, Kenji, Yamaguchi, Daichi, Nakai, Hiroshi, Nakazato, Yasushi, Matsuura, Nekka, Tamoto, Nozomu, Tokumasu, Takahiko
• Granted Patent: US 7,103,301 B2
• Time in Patent Office: Days
• US Class Current: 399/159
• CPC Class Codes: G03G 15/0208 by contact, friction or induction, e.g. liquid charging apparatus
• CPC Class Codes: G03G 15/0216 by bringing a charging member into contact with the member to be charged, e.g. roller, brush chargers
• CPC Class Codes: G03G 15/025 by bringing a charging member in the vicinity with the member to be charged, e.g. proximity charging, forming microgap
• CPC Class Codes: G03G 15/751 relating to drum G03G15/757 takes precedence
• CPC Class Codes: G03G 2215/00957 Compositions
• CPC Class Codes: G03G 2221/0005 Cleaning of residual toner

Abstract

An image forming apparatus of the present invention includes a movable body to be charged and a charger including a charging member that contacts or adjoins the body to be charged and applies a voltage, including an AC component, to the charging member for thereby charging the body. A protection substance for protecting the surface of the body from deterioration ascribable to charging is caused to exist on the body. The number of particular elements, contained in the protection substance and detected by an X-ray photon spectral analyzer (XPS) in a zone where the charging member charges the body, is held in a particular ratio to the total number of all elements constituting the outermost surface of the body and also detected by the XPS.

Claims

1. An image forming apparatus comprising:

a movable body to be charged; and

a charger comprising a charging member contacting or adjoining said body to be charged and configured to apply a voltage, including an AC component, to said charging member for thereby charging said body;

wherein a protection substance for protecting a surface of said body from deterioration ascribable to charging is caused to exist on said body, and

wherein a ratio (%) of a number of particular elements, contained in the protection substance and detected by an X-ray photon spectral analyzer (XPS) in a zone where said charging member charges said body, to a total number of all elements constituting an outermost surface of said body and detected by said XPS is expressed as;

1.52×

10<sup>−

4</sup>×

{Vpp−

2×

Vth}×

f/v×

N_α

where Vpp denotes a peak-to-peak voltage (V) of an AC voltage, f denotes a frequency (Hz) of the AC component applied to said charging member, v denotes a moving speed (mm/sec) of the surface of said body, N denotes the number of, among elements constituting the protection substance, the particular elements in a single molecule, and Vth denotes a discharge start voltage produced by;

Vth=312+6.2×

(d/ε

_opc+Gp/ε

_air)+{square root}(77.37.6×

d/ε

_opc)

where d denotes a film thickness (μ

m) of said body, ε

_opc denotes a specific dielectric constant of said body, ε

_air denotes a specific dielectric constant of a space between said body and said charging member, and Gp denotes a smallest distance (μ

m) between a surface of said charging member and the surface of said body.

2. The apparatus as claimed in claim 1, wherein the ratio of the number of the particular elements is equal to or greater than a value expressed as:

2.22×

10<sup>−

4</sup>×

{Vpp−

2×

Vth}×

f/v×

N_α

3. The apparatus as claimed in claim 2, wherein the ratio of the number of the elements constituting the protection substance to the total number of all elements constituting the outermost surface of said body is equal to or greater than a value expressed as:

2.22×

10<sup>−

4</sup>×

{Vpp−

2×

Vth}×

f/v×

N_α

4. The apparatus as claimed in claim 3, wherein N_β

is 41.

5. The apparatus as claimed in claim 1, wherein the ratio of the number of the elements constituting the protection substance to the total number of all elements constituting the outermost surface of said body is equal to or greater than a value expressed as:

1.52×

10<sup>−

4</sup>×

{Vpp−

2×

Vth}×

f/v×

N_β

where N_β

denotes a value produced by subtracting a number of hydrogen elements from the total number of elements constituting a single molecule of the protection substance.

6. The apparatus as claimed in claim 5, wherein N_β

is 41.

7. The apparatus as claimed in claim 1, wherein the protection substance comprises a fatty metal acid, and N_α

is 1.

8. The apparatus as claimed in claim 7, wherein the fatty metal acid comprises zinc stearate.

9. The apparatus as claimed in claim 1, wherein the protection substance comprises prolameller crystal powder.

10. The apparatus as claimed in claim 9, further comprising a feeding member contacting the surface of said body for coating the protection substance on said surface of said body, wherein a moving speed of said surface of said body and a moving speed of the surface of said feeding member, as measured at a contact position, are different from each other.

11. The apparatus as claimed in claim 1, wherein the smallest distance between said charging member and said body is between 1 μ

m and 100 μ

m.

12. The apparatus as claimed in claim 11, wherein said charging member includes a surface layer formed of resin.

13. The apparatus as claimed in claim 1, further comprising environment detecting means for detecting environmental conditions around said charging member, and a controller configured to control an amount of the projection substance to be fed to the surface of an image carrier, constituting said body, in accordance with said environmental conditions.

14. The apparatus as claimed in claim 1, further comprising removing means for removing an image forming substance left on the surface of said body, and charging means positioned downstream of a developing device in a direction of movement of said surface of said body, but upstream of said charging member, for charging said image forming substance left on said surface of said body.

15. In a process cartridge removaly mounted to a body of an image forming apparatus, said image forming apparatus comprising:

a movable body to be charged; and

a charger comprising a charging member contacting or adjoining said body to be charged and configured to apply a voltage, including an AC component, to said charging member for thereby charging said body;

wherein a protection substance for protecting a surface of said body from deterioration ascribable to charging is caused to exist on said body, and

wherein a ratio (%) of a number of particular elements, contained in the protection substance and detected by an X-ray photon spectral analyzer (XPS) in a zone where said charging member charges said body, to a total number of all elements constituting an outermost surface of said body and detected by said XPS is expressed as;

1.52×

10<sup>−

4</sup>×

{Vpp−

2×

Vth}×

f/v×

N_α

where Vpp denotes a peak-to-peak voltage (V) of an AC voltage, f denotes a frequency (Hz) of the AC component applied to said charging member, v denotes a moving speed (mm/sec) of the surface of said body, N denotes the number of, among elements constituting the protection substance, the particular elements in a single molecule, and Vth denotes a discharge start voltage produced by;

Vth=312+6.2×

(d/ε

_opc+Gp/ε

_air)+{square root}(77.37.6×

d/ε

_opc)

where d denotes a film thickness (μ

m) of said body, ε

_opc denotes a specific dielectric constant of said body, ε

_air denotes a specific dielectric constant of a space between said body and said charging member, and Gp denotes a smallest distance (μ

m) between a surface of said charging member and the surface of said body.

16. An image forming apparatus for forming an image on an image carrier, comprising:

a charging member contacting or adjoining a surface of the image carrier; and

a protection layer formed on the surface of the image carrier for protecting said surface from chemical deterioration ascribable to proximity discharge effected by said charging member.

17. The apparatus as claimed in claim 16, further comprising feeding means for feeding a protection substance to the surface of the image carrier to thereby form said protection layer.

18. The apparatus as claimed in claim 17, wherein said feeding member comprises a fur brush constituting a coating member that coats the protection substance on the surface of the image carrier.

19. The apparatus as claimed in claim 18, wherein the protection substance to be coated on the surface of the image carrier via said coating member comprises a molding having a preselected shape.

20. The apparatus as claimed in claim 18, wherein the protection substance to be coated on the surface of the image carrier via said coating member is contained in said coating member.

21. The apparatus as claimed in claim 18, further comprising moving means for selectively moving said coating member into or out of contact with the surface of the image carrier.

22. The apparatus as claimed in claim 17, wherein said feeding means comprises an elastic roller constituting a coating member.

23. The apparatus as claimed in claim 22, wherein the protection substance to be coated on the surface of the image carrier via said coating member comprises a molding having a preselected shape.

24. The apparatus as claimed in claim 22, wherein the protection substance to be coated on the surface of the image carrier via said coating member is contained in said coating member.

25. The apparatus as claimed in claim 22, further comprising moving means for selectively moving said coating member into or out of contact with the surface of the image carrier.

26. The apparatus as claimed in claim 17, wherein the protection substance comprises zinc stearate and is fed to the surface of the image carrier by said feeding means in an amount capable of protecting said surface from chemical deterioration.

27. The apparatus as claimed in claim 26, wherein the protection substance covers an entire image forming range of the surface of the image carrier.

28. The apparatus as claimed in claim 17, wherein said feeding means intermittently feeds the protection substance.

29. The apparatus as claimed in claim 28, wherein for intermittent feed of the protection substance, the image carrier and said feeding means are operated when image formation is under way.

30. The apparatus as claimed in claim 28, wherein for intermittent feed of the protection substance, said feeding means, contacting the image carrier, is intermittently operated during image formation.

31. The apparatus as claimed in claim 28, wherein for intermittent feed of the protection substance, said feeding means and the image carrier are intermittently brought into contact with each other during image formation.

32. The apparatus as claimed in claim 28, wherein the protection substance comprises a solid molding having a preselected shape before said protection substance is coated on the surface of the image carrier via a coating member, and

wherein for intermittent feed of the protection substance, the solid molding and said coating member are intermittently brought into contact with each other.

33. The apparatus as claimed in claim 28, wherein a coating member, containing the protection substance and contacting the image carrier, intermittently feeds said protection substance, and

wherein an amount of the protection substance contained in said coating member is variable.

34. The apparatus as claimed in claim 16, wherein said charging member does not contact the surface of the image carrier in an image forming range of said surface such that said charging member faces said surface via a preselected gap for charging.

35. The apparatus as claimed in claim 16, wherein said charging member comprises a hard charge roller formed of a hard material.

36. The apparatus as claimed in claim 16, wherein a voltage to be applied to said charging member comprises a DC voltage on which an AC component is superposed.

37. The apparatus as claimed in claim 16, wherein toner has mean circularity of 0.96 or above, but below 1.00.

38. The apparatus as claimed in claim 16, further comprising an intermediate image transfer body contacting the surface of the image carrier such that an image formed on said surface is temporarily transferred to said intermediate image transfer body.

39. The apparatus as claimed in claim 16, further comprising a process cartridge removably mounted to a body of said apparatus and loaded with at least the image carrier and said charging member.

40. The apparatus as claimed in claim 16, wherein the image carrier comprises a plurality of image carriers.

41. The apparatus as claimed in claim 16, further comprising cleaning means comprising a fur brush constituted by conductive fibers and a collection roller contacting said fur brush, wherein a voltage is applied to at least one of said fur brush and said collection roller to thereby collect toner from the image carrier by use of an electric field.

42. In a cleaning device for removing residual toner left on an image carrier after image transfer, coating means is provided for coating a protection substance on a surface of said image carrier to thereby protect said surface from proximity discharge.

43. The device as claimed in claim 42, wherein said coating means comprises a conductive fur brush contacting the protection substance to thereby coat said protection substance on the image carrier.

44. The device as claimed in claim 42, wherein said coating means comprises a conductive fur brush and a collection roller contacting said fur brush configured such that the protection substance is coated on the image carrier via said collection roller and said fur brush.

45. The device as claimed in claim 42, wherein said coating means comprises a conductive fur brush containing the protection substance.

46. The device as claimed in claim 42, wherein said coating means comprises a conductive fur brush and a collection roller contacting said fur brush and containing the protection substance, whereby said protection substance is fed to the image carrier from said collection roller via said fur brush.

47. The device as claimed in claim 42, wherein the protection substance contains zinc stearate.

48. An image forming apparatus comprising:

an image carrier for carrying a latent image thereon;

a charger configured to charge a surface of said image carrier;

a developing device configured to develop the latent image with a developer to thereby produce a toner image by depositing said developer on a developer carrier and causing said developer carrier to convey said developer to a developing zone where said developer carrier faces said image carrier; and

a cleaning device configured to remove residual toner left on said image carrier after transfer of the toner image to a recording medium;

wherein said cleaning device comprises coating means for coating a protection substance on the surface of said image carrier to thereby protect said surface from proximity discharge.

49. The apparatus as claimed in claim 48, wherein said charger comprises a charging member facing an image forming range of the surface of said image carrier via a preselected gap for charging.

50. The apparatus as claimed in claim 49, wherein spacers are mounted on said charging member and contact portions of said image carrier outside of said image forming range to thereby form the preselected gap for charging.

51. The apparatus as claimed in claim 49, wherein said charging member comprises a roller at least partly formed of hard resin.

52. The apparatus as claimed in claim 49, wherein a voltage to be applied to said charging member comprises a DC voltage on which an AC component is superposed.

53. The apparatus as claimed in claim 49, wherein said charging member has a surface having hardness of 85°

or above in JIS (Japanese Industrial Standards) A scale.

54. The apparatus as claimed in claim 48, wherein said image carrier comprises an organic photoconductive element comprising a photoconductive layer and a coating layer formed on an outermost surface of said photoconductive layer and containing inorganic grains dispersed therein.

55. The apparatus as claimed in claim 48, wherein toner contained in the developer has mean circularity of 0.96 or above.

56. The apparatus as claimed in claim 48, further comprising an intermediate image transfer body contacting the surface of said image carrier such that an image formed on said image carrier is temporarily transferred to said intermediate image transfer body.

57. The apparatus as claimed in claim 48, wherein said apparatus comprises a color image forming apparatus.

58. An image forming apparatus comprising:

an image carrier for carrying a latent image thereon;

a charger configured to charge a surface of said image carrier;

a developing device configured to develop the latent image with a developer to thereby produce a toner image by depositing said developer on a developer carrier and causing said developer carrier to convey said developer to a developing zone where said developer carrier faces said image carrier; and

a cleaning device configured to remove residual toner left on said image carrier after transfer of the toner image to a recording medium; and

feeding means for feeding a protection substance to the surface of said image carrier to thereby form a protection layer;

wherein said feeding means is positioned between, among image forming process means contacting the surface of said image carrier at positions upstream of said charger in a direction in which the surface of said image carrier moves, image forming process means closest to said charger and said charger.

59. The apparatus as claimed in claim 58, wherein said feeding means comprises a brush-like coating member configured to coat the protection substance on the surface of said image carrier.

60. The apparatus as claimed in claim 58, wherein said feeding means comprises a coating member comprising an elastic roller configured to coat the protection substance on the surface of said image carrier.

61. The apparatus as claimed in claim 58, wherein said coating member contains the protection substance.

62. The apparatus as claimed in claim 58, wherein said cleaning device comprises a blade-like removing member configured to remote the residual toner.

63. The apparatus as claimed in claim 58, wherein said cleaning device comprises a removing member comprising an electrostatic brush configured to remove the residual toner.

64. The apparatus as claimed in claim 58, wherein said charger comprises a charging member facing an image forming range of the surface of said image carrier via a preselected gap for charging.

65. The apparatus as claimed in claim 64, wherein spacers are mounted on said charging member and contact portions of said image carrier outside of said image forming range to thereby form the preselected gap for charging.

66. The apparatus as claimed in claim 64, wherein said charging member comprises a roller at least partly formed of hard resin.

67. The apparatus as claimed in claim 64, wherein a voltage to be applied to said charging member comprises a DC voltage on which an AC component is superposed.

68. The apparatus as claimed in claim 64, wherein said charging member has a surface having hardness of 850 or above in JIS A scale.

69. The apparatus as claimed in claim 58, wherein said image carrier comprises an organic photoconductive element comprising a photoconductive layer and a coating layer formed on an outermost surface of said photoconductive layer and containing inorganic grains dispersed therein.

70. The apparatus as claimed in claim 58, wherein toner contained in the developer has mean circularity of 0.96 or above.

71. The apparatus as claimed in claim 58, further comprising an intermediate image transfer body contacting the surface of said image carrier such that an image formed on said image carrier is temporarily transferred to said intermediate image transfer body.

72. The apparatus as claimed in claim 58, wherein said apparatus comprises a color image forming apparatus.

73. In a process cartridge removably mounted to a body of an image forming apparatus and loaded with a cleaning device and an image carrier, said image forming apparatus comprising:

said image carrier for carrying a latent image thereon;

a charger configured to charge a surface of said image carrier;

a developing device configured to develop the latent image with a developer to thereby produce a toner image by depositing said developer on a developer carrier and causing said developer carrier to convey said developer to a developing zone where said developer carrier faces said image carrier; and

said cleaning device configured to remove residual toner left on said image carrier after transfer of the toner image to a recording medium; and

feeding means for feeding a protection substance to the surface of said image carrier to thereby form a protection layer;

wherein said feeding means is positioned between, among image forming process means contacting the surface of said image carrier at positions upstream of said charger in a direction in which the surface of said image carrier moves, image forming process means closest to said charger and said charger.

74. In a process cartridge removably mounted to a body of an image forming apparatus and loaded with an image carrier and a developing device, said image forming apparatus comprising:

said image carrier for carrying a latent image thereon;

a charger configured to charge a surface of said image carrier;

said developing device configured to develop the latent image with a developer to thereby produce a toner image by depositing said developer on a developer carrier and causing said developer carrier to convey said developer to a developing zone where said developer carrier faces said image carrier; and

a cleaning device configured to remove residual toner left on said image carrier after transfer of the toner image to a recording medium;

wherein said cleaning device comprises coating means for coating a protection substance on the surface of said image carrier to thereby protect said surface from proximity discharge.

75. In a process cartridge removably mounted to a body of an image forming apparatus and loaded with an image carrier and a charger, said image forming apparatus comprising:

said image carrier for carrying a latent image thereon;

said charger configured to charge a surface of said image carrier;

a developing device configured to develop the latent image with a developer to thereby produce a toner image by depositing said developer on a developer carrier and causing said developer carrier to convey said developer to a developing zone where said developer carrier faces said image carrier; and

a cleaning device configured to remove residual toner left on said image carrier after transfer of the toner image to a recording medium; and

feeding means for feeding a protection substance to the surface of said image carrier to thereby form a protection layer;

wherein said feeding means is positioned between, among image forming process means contacting the surface of said image carrier at positions upstream of said charger in a direction in which the surface of said image carrier moves, image forming process means closest to said charger and said charger.