EP0552730A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Image transferring device for image forming equipment
Assignee: Ricoh Co Ltd
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Filing: 1993-01-20
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Granted: —
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Expires: 2013-01-20
Abstract
Abstract An image transferring device (1) incorporated in an image forming apparatus and capable of surely preventing a sheet from wrapping around a photoconductive element (2) and from being incompletely separated from a transfer belt (5). A transfer bias and discharge are effected to prevent changes in the resistances of the transfer belt (5) and sheet ascribable to changes in environment from translating into changes in a current to flow to the photoconductive element (2), and to efficiently dissipate a charge deposited on the belt (5). Various members constituting the device are positioned relative to one another such that the discharging effect is achievable most effectively while preventing the transfer bias from causing dielectric breakdown in any constituent part.
Inventors
- 👤 Satoshi Takano
- 👤 Itaru Matsuda
- 👤 Yuko Harasawa
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 18:13
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/14; G03G15/16; G03G15/1665; G03G15/167; G03G15/1675; G03G15/1605; G03G15/1615; G03G15/1685; G03G2215/00; G03G2215/16; G03G2215/1604; G03G2215/1623; G03G2215/1647; G03G2215/1661
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
163 words
A device incorporated in an image forming apparatus for transferring an image from a photoconductive element to a sheet, comprising: a transfer belt made of a dielectric material and contacting a surface of the photoconductive element; supporting means supporting a drive roller and a driven roller over which said transfer belt is passed; sheet transporting means for transporting the sheet to between the photoconductive element and said transfer belt; and contact electrode means connected to a high-tension power source and directly contacting said transfer belt in the vicinity of the photoconductive element; assuming that a distance between said driven roller adjoining the photoconductive element and a nip portion where said photoconductive element and said transfer belt face each other is L₁, and that a voltage to be applied from said high-tension power source to said contact electrode means is V O , said distance L₁ being selected to satisfy a relation: L₁ ≧ a x |V O | where α is 1.0 (mm/kV).
Claim 2
Dependent Claim
17 words
A device as claimed in claim 1, wherein said drive roller is made of an insulating material.
Claim 3
Dependent Claim
21 words
A device as claimed in claim 1, wherein said driven roller comprises a conductive roller held in an electrically floating state.
Claim 4
Independent Claim
158 words
A device incorporated in an image forming apparatus for transferring an image from a photoconductive element to a sheet, comprising: a transfer belt made of a dielectric material and contacting a surface of the photoconductive element; supporting means supporting a drive roller and a driven roller over which said transfer belt is passed; sheet transporting means for transporting the sheet to between the photoconductive element and said transfer belt; and contact electrode means connected to a high-tension power source and directly contacting said transfer belt in the vicinity of the photoconductive element; assuming that a distance between a nip portion where the photoconductive element and said transfer belt face each other and said contact electrode means is L₂, and that a voltage to be applied from said high-tension power source to said contact electrode means is V₀, said distance L₂ being selected to satisfy a relation: L₂ ≧ a x |V O | where α is 1.0 (mm/kV).
Claim 5
Independent Claim
193 words
A device incorporated in an image forming apparatus for transferring an image from a photoconductive element to a sheet, comprising: a transfer belt made of a dielectric material and contacting a surface of the photoconductive element; supporting means supporting a drive roller and a driven roller over which said transfer belt is passed; sheet transporting means for transporting the sheet to between the photoconductive element and said transfer belt; contact electrode means connected to a high-tension power source and directly contacting said transfer belt in the vicinity of the photoconductive element; and discharging means located downstream of said contact electrode means with respect to an intended direction of movement of said transfer belt for dissipating a charge to flow to said transfer belt, said discharging means comprising at least one contact plate located at the inside of said transfer belt; assuming that a distance between a nip portion where the photoconductive element and said transfer belt face each other and said contact electrode means is L₂, and that a distance between said contact electrode means and said contact plate is L₃, said distance L₃ being selected to satisfy a relation: L₃ ≧ L₂.
Claim 6
Dependent Claim
107 words
A device as claimed in claim 5, wherein said discharging means comprises two contact plates located downstream of said contact electrode means with respect to the intended direction of movement of said transfer belt and adjoining a run of said transfer belt along which the sheet passed said nip portion is transported, said contact plates being spaced apart from each other and facing said sheet with the intermediary of said transfer belt; assuming that a distance between said contact plates is L₄, and that said transfer belt has a lime constant τ and a process speed ν, said distance L₄ being selected to satisfy a relation: τ≦L₄/v.
Claim 7
Independent Claim
179 words
A device incorporated in an image forming apparatus for transferring an image from a photoconductive element to a sheet, comprising: a transfer belt made of a dielectric material and contacting a surface of the photoconductive element; supporting means supporting a drive roller and a driven roller over which said transfer belt is passed; sheet transporting means for transporting the sheet to between the photoconductive element and said transfer belt; contact electrode means connected to a high-tension power source and directly contacting said transfer belt in the vicinity of the photoconductive element; and discharging moans located downstream of said contact electrode means with respect to an intended direction of movement of said transfer belt for dissipating a charge to flow to said transfer belt, said discharging means comprising a contact plate located at the inside of said transfer belt; said contract plate being located at least one position adjoining a run of said transfer belt opposite to a run along which the sheet passed a nip portion where the photoconductive element and said transfer belt ace each other is transported.
Claim 8
Independent Claim
184 words
A device incorporated in an image forming apparatus for transferring an image from a photoconductive element to a sheet, comprising: a transfer belt made of a dielectric material and contacting a surface of the photoconductive element; supporting means supporting a drive roller and a driven roller over which said transfer belt is passed; sheet transporting means for transporting the sheet to between the photoconductive element and said transfer belt; contact electrode means connected to a high-tension power source and directly contacting said transfer belt in the vicinity of the photoconductive element; and transfer current control means for controlling a current to be fed from said high-tension power source such that a current to flow from said transfer belt to the photoconductive element remains constant; said transfer belt having a double layer structure made up of an outer layer having a surface resistivity of 1 x 10⁹ Ω to 1 x 10¹² Ω and an inner layer having a surface resistivity of 8 x 10⁶ Ω to 8 x 10⁸ Ω and a volume resistivity of 5 x 10⁸ Ω·cm to 5 x 10¹⁰ Ω·cm.
Claim 9
Independent Claim
148 words
A device incorporated in an image forming apparatus for transferring an image from a photoconductive element to a sheet, comprising: a transfer belt made of a dielectric material and contacting a surface of the photoconductive element; supporting means supporting a drive roller and a driven roller over which said transfer belt is passed; sheet transporting means for transporting the sheet to between the photoconductive element and said transfer belt; contact electrode means connected to a high-tension power source and directly contacting said transfer belt in the vicinity of the photoconductive element; and transfer current control means for controlling a current to be fed from said power source such that a current to flow from said transfer belt to the photoconductive element remains constant; said contact electrode means being located at a position where a charge is not injected into the sheet before said sheet faces the photocoductive element.
Claim 10
Dependent Claim
50 words
A device as claimed in claim 9, further comprising current control means for controlling a current to flow to said contact electrode means such that a difference between a current to flow to said contact electrode means and a current to flow from said transfer belt to ground remains constant.
Claim 11
Dependent Claim
83 words
A device as claimed in claim 10, further comprising a contact member adjoining a run of said transfer belt along which the sheet passed a nip portion where the photoconductive element and said transfer face face each other is transported and facing said sheet with the intermediary of said transfer belt,said contact member detecting a current to flow through said transfer belt; said current control means controlling the current to be fed from said power source on the basis of the detected current.
Claim 12
Dependent Claim
58 words
A device as claimed in claim 10, where in a particular range of voltage which said power source can apply is set, said device further comprising: detecting means for detecting a change in the set voltage; and alarming means for producing an alarm when the voltage applied from said power source does not lie in said particular range.
References Cited (Backward Citations)
No citation records indexed.
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