US4959688A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Image forming apparatus having charging and discharging means
Assignee: Canon Inc
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Filing: 1988-10-19
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Granted: 1990-09-25
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Expires: 2008-10-19
Abstract
Abstract Prior to formation of a latent image on a movable image bearing member, the latent image bearing member is charged to a predetermined potential. Then, the image bearing member is contacted to discharging means, by which the image bearing member id discharged so that a substantially uniform charge potential is provided on the image bearing member. The voltage V2 (V) (0 when grounded) applied to the discharging means, the surface potential V1 (V) of the image bearing member before being discharged by the discharging means, and the charge starting voltage V TH (V) of the image bearing member satisfy |V1-V2|≧|V TH | (V2=) when discharging grounded). By this, the charge moves from the image bearing member to the discharging means. The discharging means may be grounded or may be supplied with a voltage which is low enough not to charge alone the image bearing member. According to this invention, the absolute value of the surface potential of the image bearing member discharged by said discharging means is not dependent on the surface potential of the image bearing member before discharge, and can be made not less than |V TH |. The necessity of conventional uniform discharging means before the primary charge is eliminated so that the cost and the size of the image forming apparatus can be reduced.
Inventors
- 👤 Noribumi Koitabashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 22:17
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/02; G03G15/0266; G03G15/0208; G03G15/0216
Claims Analysis
Total Claims: 53
Claim 1
Independent Claim
147 words
An image forming apparatus, comprising: a movable image bearing member; latent image forming means for forming a latent image on a surface of said image bearing member; contact type charging means contactable to said image bearing member for charging said image bearing member before the latent image is formed on said image bearing member by said latent image forming means; and discharging means contactable to the surface of said image bearing member at a position between a latent image forming station having said latent image forming means and a charging station having said charging means where said image bearing member is electrically charged to discharge the surface of said image bearing member to provide a surface potential of said image bearing member having an absolute value which is not less than an absolute value of a charge starting voltage V TH (V) of said image bearing member.
Claim 2
Dependent Claim
147 words
An image forming apparatus, comprising: a movable image bearing member; latent image forming means for forming a latent image on a surface of said image bearing member; contact type charging means contactable to said image bearing member for charging said image bearing member before the latent image is formed on said image bearing member by said latent image forming means; and discharging means contactable to the surface of said image bearing member at a position between a latent image forming station having said latent image forming means and a charging station having said charging means where said image bearing member is electrically charged to discharge the surface of said image bearing member to provide a surface potential of said image bearing member having an absolute value which is not less than an absolute value of a charge starting voltage V TH (V) of said image bearing member.
Claim 3
Dependent Claim
45 words
An apparatus according to claim 1, further comprising means for developing the latent image formed on said image bearing member by said latent image forming means and means for transferring the developed image from the surface of said image bearing member to a transfer material.
Claim 4
Dependent Claim
23 words
An apparatus according to claim 2, wherein said transfer means is a corona transfer means having a wire electrode and a shield electrode.
Claim 5
Dependent Claim
20 words
An apparatus according to claim 2, wherein said transfer means is a transfer roller contactable to said image bearing member.
Claim 6
Dependent Claim
25 words
An apparatus according to claim 2, wherein said transfer means has a charging polarity which is the same as a polarity of the latent image.
Claim 7
Dependent Claim
12 words
An apparatus according to claim 1, wherein said discharging means is grounded.
Claim 8
Dependent Claim
27 words
An apparatus according to claim 6, wherein a surface potential of said image bearing member immediately before contact with said discharging means V1 (V) satisfies |V1|≧|V.sub.TH |.
Claim 9
Dependent Claim
36 words
An apparatus according to claim 7, wherein said charging means charges said image bearing member so that a surface potential of said image bearing member after passing by said charging means is not lower than |V1|(V).
Claim 10
Dependent Claim
88 words
An apparatus according to claim 7, wherein said transfer means includes a transfer member opposed to said image bearing member, and wherein a surface moving speed G (mm/sec) of the surface of said image bearing member and said transfer member, a length L (mm) of a discharge region wherein said image bearing member and said transfer member are opposed, measured along a length of said image bearing member, and an electrostatic capacity per unit area of said image bearing member, and a transfer current I(A), satisfy |I|≧GCL|V.sub.TH |.
Claim 11
Dependent Claim
40 words
An apparatus according to claim 7, wherein said developing means develops the latent image with toner charged to a polarity opposite to a polarity of the latent image formed on said image bearing member by said latent image forming means.
Claim 12
Dependent Claim
12 words
An apparatus according to claim 3, wherein said discharging means is grounded.
Claim 13
Dependent Claim
27 words
An apparatus according to claim 11, wherein a surface potential of said image bearing member immediately before contact with said discharging means V1 (V) satisfies |V1|≧|V.sub.TH |.
Claim 14
Dependent Claim
36 words
An apparatus according to claim 12, wherein said charging means charges said image bearing member so that a surface potential of said image bearing member after passing by said charging means is not lower than |V1|(V).
Claim 15
Dependent Claim
88 words
An apparatus according to claim 12, wherein said transfer means includes a transfer member opposed to said image bearing member, and wherein a surface of moving speed G (mm/sec) of the surface said image bearing member and said transfer member, a length L (mm) of a discharge region wherein said image bearing member and said transfer member are opposed, measured along a length of said image bearing member, and an electrostatic capacity per unit area of said image bearing member, and a transfer current I(A), satisfy |I|≧GCL|V.sub.TH |.
Claim 16
Dependent Claim
40 words
An apparatus according to claim 12, wherein said developing means develops the latent image with toner charged to a polarity opposite to a polarity of the latent image formed on said image bearing member by said latent image forming means.
Claim 17
Dependent Claim
18 words
An apparatus according to claim 1, further comprising means for applying a predetermined voltage to said discharging means.
Claim 18
Dependent Claim
42 words
An apparatus according to claim 16, wherein said voltage applying means applies to said discharging means a voltage having an absolute value which is smaller than the absolute value of the charge starting voltage V TH (V) of said image bearing member.
Claim 19
Dependent Claim
38 words
An apparatus according to claim 16, wherein the predetermined voltage applied to said discharging means V2 (V) and a surface potential of said image bearing member V1 (V) immediately before contact with said discharging means, satisfy |V1-V2|≧|V.sub.TH |.
Claim 20
Dependent Claim
36 words
An apparatus according to claim 18, wherein said charging means charges said image bearing member so that the surface potential of said image bearing member after passing by said charging means is not lower than |V1|(V).
Claim 21
Dependent Claim
90 words
An apparatus according to claim 18, wherein said transfer means includes a transfer member opposed to said image bearing member, and wherein a surface moving speed G (mm/sec) of the surface of said image bearing member and said transfer member, a length L (mm) of a discharge region wherein said image bearing member and said transfer member are opposed, measured along a length of said image bearing member, and an electrostatic capacity per unit area of said image bearing member, and a transfer current I(A), satisfy |I|≧GCL |V.sub.TH +V.sub.2 |.
Claim 22
Dependent Claim
17 words
An apparatus according to claim 1, further comprising means for applying a voltage to said charging means.
Claim 23
Dependent Claim
32 words
An apparatus according to claim 1, wherein said image bearing member is a photosensitive member, and wherein said latent image forming means includes means for exposing said photosensitive member to image information.
Claim 24
Dependent Claim
186 words
An image forming apparatus comprising: a movable image bearing member; latent image forming means for forming a latent image on a surface of said image bearing member; charging means for charging said image bearing member before the latent image is formed on said image bearing member by said latent image forming means; discharging means contactable to the surface of said image bearing member at a position between a latent image forming station having said latent image forming means and a charging station having said charging means where said image bearing member is electrically charged to discharge the surface of said image bearing member to provide a surface potential of said image bearing member having an absolute value which is not less than an absolute value of a charge starting voltage V TH (V) of said image bearing member; and means for developing the latent image formed on said image bearing member by said latent image forming means and means for transferring the developed image from the surface of said image bearing member to a transfer material; wherein said transfer means also functions as said charging means.
Claim 25
Dependent Claim
186 words
An image forming apparatus comprising: a movable image bearing member; latent image forming means for forming a latent image on a surface of said image bearing member; charging means for charging said image bearing member before the latent image is formed on said image bearing member by said latent image forming means; discharging means contactable to the surface of said image bearing member at a position between a latent image forming station having said latent image forming means and a charging station having said charging means where said image bearing member is electrically charged to discharge the surface of said image bearing member to provide a surface potential of said image bearing member having an absolute value which is not less than an absolute value of a charge starting voltage V TH (V) of said image bearing member; and means for developing the latent image formed on said image bearing member by said latent image forming means and means for transferring the developed image from the surface of said image bearing member to a transfer material; wherein said transfer means also functions as said charging means.
Claim 26
Dependent Claim
18 words
An apparatus according to claim 23, further comprising means for applying a predetermined voltage to said discharging means.
Claim 27
Dependent Claim
42 words
An apparatus according to claim 24, wherein said voltage applying means applies to said discharging means a voltage having an absolute value which is smaller than the absolute value of the charge starting voltage V TH (V) of said image bearing member.
Claim 28
Dependent Claim
37 words
An apparatus according to claim 24, wherein the predetermined voltage applied to said discharging means V2 (V) and surface potential of said image bearing member V1 (v) immediately before contact with said discharging means, satisfy |V1-V2|≧|V.sub.TH |.
Claim 29
Dependent Claim
36 words
An apparatus according to claim 26, wherein said charging means charges said image bearing member so that the surface potential of said image bearing member after passing by said charging means is not lower than |V1|(V).
Claim 30
Dependent Claim
90 words
An apparatus according to claim 26, wherein said transfer means includes a transfer member opposed to said image bearing member, and wherein a surface moving speed G (mm/sec) of the surface of said image bearing member and said transfer member, a length L (mm) of a discharge region wherein said image bearing member and said transfer member are opposed, measured along a length of said image bearing member, and an electrostatic capacity per unit area of said image bearing member, and a transfer current I(A), satisfy |I|≧GCL |V.sub.TH +V.sub.2 |.
Claim 31
Dependent Claim
23 words
An apparatus according to claim 23, wherein said transfer means is a corona transfer means having a wire electrode and a shield electrode.
Claim 32
Dependent Claim
20 words
An apparatus according to claim 23, wherein said transfer means is a transfer roller contactable to said image bearing member.
Claim 33
Dependent Claim
17 words
An apparatus according to claim 23, further comprising means for applying a voltage to said charging means.
Claim 34
Dependent Claim
32 words
An apparatus according to claim 23, wherein said image bearing member is a photosensitive member, and wherein said latent image forming means includes means for exposing said photosensitive member to image information.
Claim 35
Dependent Claim
40 words
An apparatus according to claim 23, wherein said developing means develops the latent image with toner charged to a polarity opposite to a polarity of the latent image formed on said image bearing member by said latent image forming means.
Claim 36
Dependent Claim
25 words
An apparatus according to claim 23, wherein said transfer means has a charging polarity which is the same as a polarity of the latent image.
Claim 37
Dependent Claim
145 words
An image forming apparatus, comprising: a movable image bearing member; latent image forming means for forming a latent image on a surface of said image bearing member; charging means for charging said image bearing member before the latent image is formed on said image bearing member by said latent image forming means; and discharging means contactable to the surface of said image bearing member at a position between a latent image forming station having said latent image forming means and a charging station having said charging means where said image bearing member is electrically charged to discharge the surface of said image bearing member to provide a surface potential of said image bearing member having an absolute value which is not less than an absolute value of a charge starting voltage V TH (V) of said image bearing member; wherein said discharging means is grounded.
Claim 38
Dependent Claim
145 words
An image forming apparatus, comprising: a movable image bearing member; latent image forming means for forming a latent image on a surface of said image bearing member; charging means for charging said image bearing member before the latent image is formed on said image bearing member by said latent image forming means; and discharging means contactable to the surface of said image bearing member at a position between a latent image forming station having said latent image forming means and a charging station having said charging means where said image bearing member is electrically charged to discharge the surface of said image bearing member to provide a surface potential of said image bearing member having an absolute value which is not less than an absolute value of a charge starting voltage V TH (V) of said image bearing member; wherein said discharging means is grounded.
Claim 39
Dependent Claim
45 words
An apparatus according to claim 35, further comprising means for developing the latent image formed on said image bearing member by said latent image forming means and means for transferring the developed image from the surface of said image bearing member to a transfer material.
Claim 40
Dependent Claim
16 words
An apparatus according to claim 36, wherein said transfer means also functions as said charging means.
Claim 41
Dependent Claim
27 words
An apparatus according to claim 35, wherein a surface potential of said image bearing member immediately before contact with said discharging means V1 (V) satisfies |V1|≧|V.sub.TH |.
Claim 42
Dependent Claim
36 words
An apparatus according to claim 38, wherein said charging means charges said image bearing member so that a surface potential of said image bearing member after passing by said charging means is not lower than |V1|(V).
Claim 43
Dependent Claim
89 words
An apparatus according to claim 38, wherein said transfer means includes a transfer member opposed to said image bearing member, and wherein a surface moving speed G (mm/sec) of the surface of said image bearing member and said transfer member, a length L (mm) of a discharge region wherein said image bearing member and said transfer member are opposed, measured along a length of said image bearing member, and an electrostatic capacity per unit area of said image bearing member, and a transfer current (IA), satisfy |I|≧GCL |V.sub.TH |.
Claim 44
Dependent Claim
40 words
An apparatus according to claim 38, wherein said developing means develops the latent image with toner charged to a polarity opposite to a polarity of the latent image formed on said image bearing member by said latent image forming means.
Claim 45
Dependent Claim
23 words
An apparatus according to claim 36, wherein said transfer means is a corona transfer means having a wire electrode and a shield electrode.
Claim 46
Dependent Claim
20 words
An apparatus according to claim 36, wherein said transfer means is a transfer roller contactable to said image bearing member.
Claim 47
Dependent Claim
17 words
An apparatus according to claim 35, further comprising means for applying a voltage to said charging means.
Claim 48
Dependent Claim
31 words
A apparatus according to claim 35, wherein said image bearing member is photosensitive member, and wherein said latent image forming means includes means for exposing said photosensitive member to image information.
Claim 49
Dependent Claim
40 words
An apparatus according to claim 36, wherein said developing means develops the latent image with toner charged to a polarity opposite to a polarity of the latent image formed on said image bearing member by said latent image forming means.
Claim 50
Dependent Claim
25 words
An apparatus according to claim 36, wherein said transfer means has a charging polarity which is the same as a polarity of the latent image.
Claim 51
Dependent Claim
79 words
An image forming apparatus, comprising: a movable image bearing member; latent image forming means for forming a latent image on said image bearing member electrically charged to a predetermined potential level; charging means contactable to said image bearing member to charge it to a potential level higher than the predetermined potential level before said latent image forming means forms the latent image; and means contactable to said image bearing member to lower the potential level to the predetermined level.
Claim 52
Dependent Claim
79 words
An image forming apparatus, comprising: a movable image bearing member; latent image forming means for forming a latent image on said image bearing member electrically charged to a predetermined potential level; charging means contactable to said image bearing member to charge it to a potential level higher than the predetermined potential level before said latent image forming means forms the latent image; and means contactable to said image bearing member to lower the potential level to the predetermined level.
Claim 53
Dependent Claim
32 words
An apparatus according to claim 48, wherein said charging means functions also to transfer an image formed on said image bearing member before said latent image is formed, onto a transfer material.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-09-24 | 1994-03-26 | 1994-09-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-24 | 1998-03-26 | 1998-09-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-24 | 2002-03-26 | 2002-09-25 | $7700.00 | Window Closed / Lapsed |