US4847657A — Electrophotographic apparatus for depositing deve…

Claim 1

Independent Claim 125 words

An electrophotgraphic apparatus, comprising: an image bearing member; means for developing a latent image formed on said image bearing member by depositing a developer onto a light potential area of the latent image which has been exposed to light; bias voltage applying means for applying a bias voltage to said developing means; and means for exposing a non-image-forming area of said image bearing member to light; wherein the bias voltage applied to said developing means for the image forming area is different from that for the non-image-forming area, and wherein the bias voltage for the image forming area is effective to deposit the developer in the light potential portion, whereas the bias voltage for the non-image-forming area is effective to prevent deposition of the developer.

Claim 2

Dependent Claim 125 words

An electrophotgraphic apparatus, comprising: an image bearing member; means for developing a latent image formed on said image bearing member by depositing a developer onto a light potential area of the latent image which has been exposed to light; bias voltage applying means for applying a bias voltage to said developing means; and means for exposing a non-image-forming area of said image bearing member to light; wherein the bias voltage applied to said developing means for the image forming area is different from that for the non-image-forming area, and wherein the bias voltage for the image forming area is effective to deposit the developer in the light potential portion, whereas the bias voltage for the non-image-forming area is effective to prevent deposition of the developer.

Claim 3

Dependent Claim 31 words

An apparatus according to claim 1, wherein said developing means develops using a latent image by the developer chargeable to the polarity of the charging polarity of said image bearing member.

Claim 4

Dependent Claim 68 words

An apparatus according to claim 2, wherein said bias voltage applying means applies, for the non-image forming area of said image bearing member, of bias voltage including a DC component having the same polarity as that of the charging polarity of said image bearing member and having an absolute value smaller than the absolute value of the surface potential of the non-image-forming area of said image bearing member.

Claim 5

Dependent Claim 51 words

An apparatus according to claim 3, wherein said bias voltage applying means applies, for the non-image forming area of said image bearing member, to said developing means a bias voltage including a DC component which is different from the surface potential of the non-image-forming area by not more than 300 V.

Claim 6

Dependent Claim 54 words

An apparatus according to claim 1, wherein said bias voltage applying means applies, for the image forming area, to said developing means a bias voltage provided by superimposing a DC current and an alternating current, and applies, for the non-image forming area, to the developing means a bias voltage including only a DC component.

Claim 7

Dependent Claim 144 words

An electrophotographic apparatus comprising: developing means for depositing, in a first mode of operation of said apparatus, a developer on the dark potential portion of a latent image formed on an image bearing means which has not been exposed to light, and for depositing, in a second mode of operation of said apparatus, another or the same developer on a light potential area of the latent image on the image bearing means which is exposed to light; exposure means for exposing a non-image forming area of the image bearing means in both of said first mode and said second mode; and bias voltage applying means for applying a bias voltage to said developing means, wherein said bias voltage applying means applies a bias voltage for preventing deposition of the developer in the non-image-forming area in both of said first mode and said second mode.

Claim 8

Dependent Claim 144 words

An electrophotographic apparatus comprising: developing means for depositing, in a first mode of operation of said apparatus, a developer on the dark potential portion of a latent image formed on an image bearing means which has not been exposed to light, and for depositing, in a second mode of operation of said apparatus, another or the same developer on a light potential area of the latent image on the image bearing means which is exposed to light; exposure means for exposing a non-image forming area of the image bearing means in both of said first mode and said second mode; and bias voltage applying means for applying a bias voltage to said developing means, wherein said bias voltage applying means applies a bias voltage for preventing deposition of the developer in the non-image-forming area in both of said first mode and said second mode.

Claim 9

Dependent Claim 66 words

An apparatus according to claim 6, wherein in said first mode, said developing means develops the latent image by a developer chargeable to a polarity opposite to the charge of said image bearing means, and in said second mode, said developing means develops the latent image by a developer chargeable to a polarity, the same as the polarity of the charge of said image bearing means.

Claim 10

Dependent Claim 38 words

An apparatus according to claim 6, further comprising control means for controlling said exposure means so as to decrease the amount of exposure of said image bearing member in said second mode as compared with said first mode.

Claim 11

Dependent Claim 38 words

An Apparatus according to claim 8, wherein said bias voltage applying means applies a bias voltage having a DC component for the non-image forming area which is the same in said first mode and in said second mode.

Claim 12

Dependent Claim 69 words

An apparatus according to claim 6, wherein the amount of exposure produced by said exposure means of the non-image forming area of the image bearing means is the same in said first mode and in said second mode, and wherein said bias voltage applying means applies a bias voltage that is different in said first mode and in said second mode to prevent toner deposition in the non-image-forming area.

Claim 13

Dependent Claim 27 words

An apparatus according to claim 6, wherein said developing means includes at least two developing devices which are used for said first mode and said second mode.

Claim 14

Dependent Claim 28 words

An apparatus according to claim 6, wherein said apparatus is capable of accommodating either of first mode developing device or second mode developing device as said developing means.

Claim 15

Dependent Claim 35 words

An apparatus according to claim 6, wherein in said second mode, said bias voltage applying means applies different bias voltages to said developing means, for the image forming area and for the non-image forming area.

Claim 16

Dependent Claim 54 words

An apparatus according to claim 12, wherein said bias voltage applying means applies, for the image forming area, to said developing means a bias voltage provided by superimposing a DC current and an alternating current, and applies, for the non-image forming area, to the developing means a bias voltage including only a DC component.

Claim 17

Dependent Claim 87 words

An apparatus according to claim 7, wherein in said second mode, the surface potential of the non-image forming area of the image bearing means and the DC component of the bias voltage for the non-image forming area have the same polarity, and wherein the absolute value of the DC component of the bias voltage for the non-image-forming area is larger in the first mode and smaller in the second mode than the absolute value of the surface potential of the non-image-forming area of said image bearing means.

Claim 18

Dependent Claim 36 words

An apparatus according to claim 15, wherein the difference between the surface potential of the non-image-forming area of said image bearing means and the DC component of the bias voltage is not more than 300 V.

Claim 19

Dependent Claim 152 words

An electrophotographic apparatus, comprising; an image bearing member; charging means for uniformly charging said image bearing member; developing means for developing a latent image formed on said image bearing member by a developer charged to a polarity, the same as the polarity to which said image bearing member is charged; bias voltage applying means for applying a bias voltage to said developing means; first control means for changing the bias voltage depending on whether said bias voltage is used for controlling the operation of said developing means with respect to the image forming area or the non-image-forming area; exposure means for exposing the non-image forming area of said image-bearing member; and second control means for controlling said exposure means, wherein said first control means changes the bias voltage at a position on said image bearing member which corresponds to a position thereof where said second control means turns off said exposure means.

Claim 20

Dependent Claim 152 words

An electrophotographic apparatus, comprising; an image bearing member; charging means for uniformly charging said image bearing member; developing means for developing a latent image formed on said image bearing member by a developer charged to a polarity, the same as the polarity to which said image bearing member is charged; bias voltage applying means for applying a bias voltage to said developing means; first control means for changing the bias voltage depending on whether said bias voltage is used for controlling the operation of said developing means with respect to the image forming area or the non-image-forming area; exposure means for exposing the non-image forming area of said image-bearing member; and second control means for controlling said exposure means, wherein said first control means changes the bias voltage at a position on said image bearing member which corresponds to a position thereof where said second control means turns off said exposure means.

Claim 21

Dependent Claim 59 words

An apparatus according to claim 17, wherein said first control means controls said bias voltage applying means so that a DC component of the bias voltage for the non-image-forming area has the same polarity, as that of said image bearing member and has an absolute value smaller than the potential of the non-image-forming area of said image bearing member.

Claim 22

Dependent Claim 40 words

An apparatus according to claim 18, wherein said first control means controls the bias voltage so that the difference between the potential of the non-image-forming area and the DC component of the bias voltage is not more than 300 V.

Claim 23

Dependent Claim 47 words

An apparatus according to claim 17, wherein said first control means controls said bias voltage applying means so that a bias voltage of superimposed AC and DC is applied for the image forming area, whereas for the non-image-forming area, the bias voltage has only a DC component.

Claim 24

Dependent Claim 77 words

An apparatus according to claim 17, wherein said first control means changes the bias voltage at a position on said image bearing member which corresponds to a position where said second control means activates said exposure means and wherein said second control means actuates said exposure means at a position after the position where said first control means changes the bias voltage adjacent to a boundary between the image forming area and the non-image-forming area subsequent thereto.

Claim 25

Dependent Claim 46 words

An apparatus according to claim 17, wherein said first control means changes the bias voltage at a position after the position where said second control means turns off said exposure means adjacent to a boundary between the non-image-forming area and the image forming area subsequent thereto.

Claim 26

Dependent Claim 85 words

An image forming apparatus, comprising: an image bearing member; means for forming a latent image having a high potential portion and a low potential portion on said image bearing member; means for developing the latent image by depositing a developer on the low potential portion of the latent image; means for electrically discharging a non-image area of said image bearing member; and control means for controlling said developing means to prevent the developer from being deposited on the non-image area of said image bearing member.

Claim 27

Dependent Claim 85 words

An image forming apparatus, comprising: an image bearing member; means for forming a latent image having a high potential portion and a low potential portion on said image bearing member; means for developing the latent image by depositing a developer on the low potential portion of the latent image; means for electrically discharging a non-image area of said image bearing member; and control means for controlling said developing means to prevent the developer from being deposited on the non-image area of said image bearing member.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1992-07-10	1993-01-09	1993-07-11	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1996-07-10	1997-01-09	1997-07-11	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2000-07-10	2001-01-09	2001-07-11	$7700.00	Window Closed / Lapsed

Electrophotographic apparatus for depositing developer only on the image area of the image bearing member

Abstract

Inventors

Bibliographic Details

Claims Analysis

References Cited (Backward Citations)

USPTO Annuity & Maintenance Windows

Assigned Categories & Tags

Assign Category Tag