EP0428172A2
Expired / Lapsed
EP
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An image forming apparatus
Assignee: Canon Inc
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Filing: 1990-11-15
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Granted: —
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Expires: 2010-11-15
Abstract
Abstract An image forming apparatus includes a movable image bearing member (1); an image forming device (3) for forming an image on the image bearing member (1); a charging member (5) press-contacted to or faced to the image bearing member (1) to transfer the image from the image bearing member (1) onto the transfer material (P) passed therebetween; a bias voltage applying device (8) for applying a bias voltage to the charging member (5), wherein the voltage applying device constant-voltage-controlled the charging member (5) in a period when an image region of the image bearing member (1) is present in the transfer position, and constant-current-controls the charging member (5) in another period, and wherein a voltage applied to the charging member (5) during the constant voltage control is a sum of a voltage provided during the constant current control and a predetermined voltage.
Inventors
- 👤 Jun Asai
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-09 02:35
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/14; G03G15/16; G03G15/1665; G03G15/167; G03G15/1675
Claims Analysis
Total Claims: 25
Claim 1
Independent Claim
127 words
An image forming apparatus, comprising: a movable image bearing member; image forming means for forming an image on said image bearing member; a charging member press-contacted to or faced to said image bearing member to transfer the image from said image bearing member onto the transfer material passed therebetween; bias voltage applying means for applying a bias voltage to said charging member, wherein said voltage applying means constant-voltage-controls said charging member in a period when an image region of said image bearing member is present in the transfer position, and constant-current-controls said charging member in another period, and wherein a voltage applied to said charging member during the constant voltage control is a sum of a voltage provided during the constant current control and a predetermined voltage.'
Claim 2
Dependent Claim
127 words
An image forming apparatus, comprising: a movable image bearing member; image forming means for forming an image on said image bearing member; a charging member press-contacted to or faced to said image bearing member to transfer the image from said image bearing member onto the transfer material passed therebetween; bias voltage applying means for applying a bias voltage to said charging member, wherein said voltage applying means constant-voltage-controls said charging member in a period when an image region of said image bearing member is present in the transfer position, and constant-current-controls said charging member in another period, and wherein a voltage applied to said charging member during the constant voltage control is a sum of a voltage provided during the constant current control and a predetermined voltage.'
Claim 3
Dependent Claim
21 words
An apparatus according to Claim 1, wherein said charging member and the transfer material having resistances variable depending on ambient condition.
Claim 4
Dependent Claim
18 words
An apparatus according to Claim 2, wherein the ambient condition includes an ambient humidity and an ambient temperature.
Claim 5
Dependent Claim
55 words
An apparatus according to Claim 1, wherein said image forming means includes charging means for charging said image bearing member, exposure means for exposing said image bearing member to light in accordance with an image signal, and means for forming a toner image by depositing toner to a latent image provided by said exposure means.
Claim 6
Dependent Claim
40 words
An apparatus according to Claim 4, wherein the voltage provided during the constant current control corresponds to a sum of a voltage across said charging member and a voltage across said image bearing member not charged by said charging means.
Claim 7
Dependent Claim
28 words
An apparatus according to Claim 5, wherein the predetermined voltage is a voltage corresponding to a resistance of the transfer material and a potential of the toner image.
Claim 8
Dependent Claim
47 words
An apparatus according to Claim 4, wherein the voltage provided during the constant current control corresponds to a sum of a voltage across said charging member, a voltage across said image bearing member not charged by said charging means and a charge potential of the toner image.
Claim 9
Dependent Claim
18 words
An apparatus according to Claim 7, wherein the predetermined voltage corresponds to the resistance of the transfer material.
Claim 10
Dependent Claim
32 words
An apparatus according to Claim 6, wherein the resistance of the transfer material is a highest resistance of transfer material usable with said apparatus under a low temperature and low humidity condition.
Claim 11
Dependent Claim
32 words
An apparatus according to Claim 8, wherein the resistance of the transfer material is a highest resistance of transfer material usable with said apparatus under a low temperature and low humidity condition.
Claim 12
Dependent Claim
31 words
An apparatus according to Claim 9, wherein the transfer material exhibiting the highest resistance is an OHP sheet under the temperature of 5 o C and the humidity of 10 %RH.
Claim 13
Dependent Claim
31 words
An apparatus according to Claim 10, wherein the transfer material exhibiting the highest resistance is an OHP sheet under the temperature of 5 o C and the humidity of 10 %RH.
Claim 14
Dependent Claim
36 words
An apparatus according to Claim 6, wherein the resistance of the transfer material is a resistance of the transfer material usable with said apparatus and exhibiting a lowest resistance under a high temperature and humidity condition.
Claim 15
Dependent Claim
36 words
An apparatus according to Claim 8, wherein the resistance of the transfer material is a resistance of the transfer material usable with said apparatus and exhibiting a lowest resistance under a high temperature and humidity condition.
Claim 16
Dependent Claim
26 words
An apparatus according to Claim 13, wherein the transfer material is plain paper under the temperature of 32.5 o C and the humidity of 90 %RH.
Claim 17
Dependent Claim
26 words
An apparatus according to Claim 14, wherein the transfer material is plain paper under the temperature of 32.5 o C and the humidity of 90 %RH.
Claim 18
Dependent Claim
17 words
An apparatus according to Claim 1, wherein said charging member is contacted to said image bearing member.
Claim 19
Dependent Claim
23 words
An apparatus according to Claim 4, wherein the image region is a region in which said image bearing member has the toner image.
Claim 20
Dependent Claim
27 words
An apparatus according to Claim 1, wherein said transfer position is a position where said image bearing member and said charging member are faced to each other.
Claim 21
Dependent Claim
22 words
An apparatus according to Claim 1, wherein the constant current control is carried out before image formation on said image bearing member.
Claim 22
Dependent Claim
25 words
An apparatus according to Claim 4, wherein the constant current control is carried out before said image bearing member is charged by said charging means.
Claim 23
Dependent Claim
17 words
An apparatus according to Claim 1, wherein said charging member is in the form of a roller.
Claim 24
Dependent Claim
17 words
An apparatus according to Claim 1, wherein said charging member is in the form of a belt.
Claim 25
Dependent Claim
14 words
An apparatus according to Claim 1, wherein said charging member is made of EPDM.
References Cited (Backward Citations)
US5179397A
Cited
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