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EP0520819A2
Expired / Lapsed
EP
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Image forming apparatus having charging member
Assignee: Canon Inc
•
Filing: 1992-06-26
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Granted: —
•
Expires: 2012-06-26
Abstract
Abstract An image forming apparatus includes image forming device for forming an image on a recording material (P), the image forming device including an image bearing member (1), a transfer member (6) for transferring the image on the image bearing member (1) and a voltage source (3) for supplying a voltage to the transfer member; and determining device for determining a substantial intersection between an actual voltage-current characteristic curve between the transfer (6) member and the image bearing member (1) and a predetermined voltage-current curve predetermined for the transfer member (6), and for determining a bias to be applied to the transfer member during image transfer operation of the basis of the intersection.
Inventors
- 👤 Koichi C/O Canon Kabushiki Kaisha Hiroshima
- 👤 Masahiro C/O Canon Kabushiki Kaisha Goto
- 👤 Yoji C/O Canon Kabushiki Kaisha Serizawa
- 👤 Makoto C/O Canon Kabushiki Kaisha Takeuchi
- 👤 Tatsunori c/o Canon Kabushiki Kaisha Ishiyama
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 13:31
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/14; G03G15/16; G03G15/1665; G03G15/167; G03G15/1675; G03G15/02; G03G15/0266; G03G2215/00; G03G2215/02; G03G2215/021
Claims Analysis
Total Claims: 62
Claim 1
Independent Claim
102 words
An image forming apparatus, comprising: image forming means for forming an image on a recording material, said image forming means including an image bearing member, a charging member for charging said image bearing member and a voltage source for supplying electric power to said charging member; and determining means for determining a substantial intersection between an actual voltage current characteristic curve between said charging member and said image bearing member and a predetermined voltage-current curve predetermined for said charging member, and for determining a bias to be applied to said charging member during image forming operation on the basis of the intersection.
Claim 2
Dependent Claim
32 words
An apparatus according to Claim 1, wherein the actual voltage-current characteristic curve is determined on the basis of electric currents provided when said charging member is constant-voltage controlled with plural constant voltages.
Claim 3
Dependent Claim
17 words
An apparatus according to Claim 2, wherein the electric currents are currents flowing through said charging member.
Claim 4
Dependent Claim
30 words
An apparatus according to Claim 1, wherein the actual voltage-current characteristic curve is determined on the basis of voltages produced when said charging member is constant-current-controlled with plural constant currents.
Claim 5
Dependent Claim
24 words
An apparatus according to Claim 2, wherein the intersection is determined by gradually increasing or decreasing the voltage during the constant voltage control operation.
Claim 6
Dependent Claim
22 words
An apparatus according to Claim 2, wherein said charging member is controlled with pulse width modulation during the constant voltage control operation.
Claim 7
Dependent Claim
29 words
An apparatus according to Claim 5, wherein the intersection is determined by gradually increasing or decreasing the plural voltages through pulse width modulation during the constant voltage control operation.
Claim 8
Dependent Claim
19 words
An apparatus according to Claim 1, wherein the predetermined voltage-current curve indicates a different voltage if current is different.
Claim 9
Dependent Claim
18 words
An apparatus according to Claim 8, wherein the predetermined voltage-current curve indicates a smaller current for larger voltage.
Claim 10
Dependent Claim
27 words
An apparatus according to Claim 1, wherein said charging member is a transfer member for transferring an image from said image bearing member to the recording material.
Claim 11
Dependent Claim
19 words
An apparatus according to Claim 10, wherein said charging member is contactable to a backside of the recording material.
Claim 12
Dependent Claim
19 words
An apparatus according to Claim 1 or 11, wherein said charging member is contactable to said image bearing member.
Claim 13
Dependent Claim
28 words
An apparatus according to Claim 11, wherein said charging member is constant-voltage controlled during image transfer operation on the basis of a voltage determined by said determining means.
Claim 14
Dependent Claim
25 words
An apparatus according to Claim 10, wherein the actual voltage-current characteristic curve is determined while the recording material is absent in an image transfer position.
Claim 15
Dependent Claim
62 words
An apparatus according to Claim 1, wherein said apparatus is operable in a first mode for determining the bias to be applied to said charging member so that it is within a predetermined range from the intersection and in a second mode for determining the intersection while applying to the charging member the bias determined in an operation of the first mode.
Claim 16
Dependent Claim
83 words
An apparatus according to Claim 15, wherein a plurality of biases is applied to the charging member in the first mode, and the bias is determined on the basis of plural currents and voltages produced in the operation of the first mode, and in the second mode, the bias determined in the first mode is applied to said charging member, and a plurality of currents and voltages are produced, wherein the intersection is determined on the basis of the plural currents and voltages.
Claim 17
Dependent Claim
22 words
An apparatus according to Claim 16, wherein the intersection is determined on the basis of averages of the plural currents and voltages.
Claim 18
Dependent Claim
55 words
An apparatus according to Claim 17, wherein said charging member is a rotatable member, the bias determined in an operation of the first mode is applied to said charging member during an operation of the second mode for one full turn of said charging member, and currents and voltages are averaged to determine the intersection.
Claim 19
Dependent Claim
50 words
An apparatus according to Claim 15, 16, 17 or 18, wherein an operation of the first mode is carried out before a printing operation of said apparatus on a recording material, and wherein an operation of the second mode is carried out in a printing operation for the recording material.
Claim 20
Dependent Claim
37 words
An apparatus according to Claim 16, wherein a period in which a current or voltage is sampled with a bias voltage applied to said charging member is shorter in the first mode than in the second mode.
Claim 21
Dependent Claim
41 words
An apparatus according to Claim 16, wherein said charging member is supplied with different biases in the second mode to determine the intersection, and wherein intervals between different bias voltages are shorter in the second mode than in the first mode.
Claim 22
Dependent Claim
40 words
An apparatus according to Claim 2, wherein said image forming means forms a toner image on a recording material, and the plural voltages during the constant voltage control operation has a same polarity as a polarity of the toner image.
Claim 23
Dependent Claim
103 words
An image forming apparatus, comprising: an image bearing member; image forming means for forming an image on said image bearing member; transfer charging member for transferring the image from said image bearing member onto a recording material; a voltage source for supplying electric power to said transfer charging member; constant voltage control means for constant-voltage-controlling said transfer charging member at a predetermined voltage; and wherein the predetermined voltage during transfer operation and current through said transfer charging member during a constant voltage operation in non-transfer operation, are changed in accordance with voltage-current characteristics between said transfer charging member and said image bearing member.
Claim 24
Dependent Claim
29 words
An apparatus according to Claim 23, wherein with increase of a resistance of said transfer charging member, the predetermined voltage increases, and the electric current during non-transfer operation decreases.
Claim 25
Dependent Claim
21 words
An apparatus according to Claim 23, wherein during the constant voltage control, the predetermined voltage is controlled with pulse width modulation.
Claim 26
Dependent Claim
20 words
An apparatus according to Claim 23, wherein said transfer charging member is contactable to a backside of the recording material.
Claim 27
Dependent Claim
18 words
A apparatus according to Claim 26, wherein said transfer charging member is contactable to said image bearing member.
Claim 28
Dependent Claim
116 words
An image forming apparatus, comprising: image forming means for forming an image on a recording material, said image forming means including an image bearing member, a charging member for charging said image bearing member and a voltage source for supplying electric power to said charging member; constant voltage control means for constant-voltage-controlling said charging member with a predetermined voltage; and wherein a constant voltage control operation of said constant voltage control operation is carried out for said charging member a plurality of times with different voltages, and a voltage applied to said charging member during image forming operation is determined on the basis of plural currents through said charging member during plural constant voltage control operations.
Claim 29
Dependent Claim
21 words
An apparatus according to Claim 28, wherein the plural voltages are applied by gradually increasing or decreasing a voltage applied thereto.
Claim 30
Dependent Claim
18 words
An apparatus according to Claim 28 or 29, wherein the plural voltages are controlled with pulse width modulation.
Claim 31
Dependent Claim
27 words
An apparatus according to Claim 28, wherein said charging member is a transfer member for transferring the image from said image bearing member onto the recording material.
Claim 32
Dependent Claim
20 words
An apparatus according to Claim 31, wherein said charging member is contactable to a back side of the recording material.
Claim 33
Dependent Claim
19 words
An apparatus according to Claim 28 or 32, wherein said charging member is contactable to said image bearing member.
Claim 34
Dependent Claim
24 words
An apparatus according to Claim 32, wherein said charging member is constant-voltage-controlled during image transfer operation on the basis of the thus determined voltage.
Claim 35
Dependent Claim
24 words
An apparatus according to Claim 31, wherein the constant-voltage-control operation is carried out while the recording material is absent in an image transfer position.
Claim 36
Dependent Claim
97 words
An apparatus according to Claim 28, wherein said apparatus is operable in a first mode in which the voltage of the constant voltage control operation is changed so as to be within a predetermined range from a voltage to be applied to said charging member to determine the voltage and in a second mode in which said charging member is constant-voltage-controlled with the voltage determined in the first mode, and the voltage applied to the charging member during image forming operation is determined on the basis of plural currents detected during the last mentioned constant voltage control.
Claim 37
Dependent Claim
28 words
An apparatus according to Claim 36, wherein the voltage to be applied to said charging member is determined on the basis of an average of the plural currents.
Claim 38
Dependent Claim
35 words
An apparatus according to Claim 37, wherein said charging member is a rotatable member, and wherein the constant voltage control in the second mode is carried out for one full turn of said charging member.
Claim 39
Dependent Claim
44 words
An apparatus according to Claim 36, 37 or 38, wherein an operation of the first mode is carried out before printing operation on the recording material, and an operation of the second mode is carried out in a printing operation on the recording material.
Claim 40
Dependent Claim
30 words
An apparatus according to Claim 36, wherein the electric current is sampled during the constant voltage control for a shorter period in the first mode than in the second mode.
Claim 41
Dependent Claim
35 words
An apparatus according to Claim 36, in the second mode, said charging member is constant-voltage controlled with plural voltages, and interval between the voltages is shorter in the second mode than in the first mode.
Claim 42
Dependent Claim
41 words
An apparatus according to Claim 28, wherein said image forming means forms a toner image on the recording material, and plural voltages during the constant voltage control has a polarity which is the same as the polarity of the toner image.
Claim 43
Dependent Claim
176 words
An image forming apparatus, comprising: image forming means for forming an image on a recording material, said image forming means including an image bearing member, a charging member for charging said image bearing member and a voltage source for supplying electric power to said charging member; detecting means for detecting a plurality of sample values relating to a resistance of said charging member; and determining means for determining a voltage to be applied to said charging member during image forming operation of said apparatus in accordance with an output of said detecting means, wherein said detecting means carries out its detecting operation in a first mode in which a voltage or current applied to said charging member is increased or decreased with a first increment and in a second mode in which said charging member is supplied with a voltage or current which is determined on the basis of the sample values in the first mode and which is increased or decreased with a second increment, wherein the second increment is smaller than the first increment.
Claim 44
Dependent Claim
22 words
An apparatus according to Claim 43, wherein the voltage or current applied to said charging member is controlled with pulse width modulation.
Claim 45
Dependent Claim
27 words
An apparatus according to Claim 43, wherein said charging member is a transfer member for transferring the image from said image bearing member onto the recording material.
Claim 46
Dependent Claim
19 words
An apparatus according to Claim 45, wherein said charging member is contactable to a backside of the recording material.
Claim 47
Dependent Claim
19 words
An apparatus according to Claim 43 or 46, wherein said charging member is contactable to said image bearing member.
Claim 48
Dependent Claim
19 words
An apparatus according to Claim 43, wherein the sampled values are currents produced when said charging member is constant-voltage-controlled.
Claim 49
Dependent Claim
19 words
An apparatus according to Claim 43, wherein the sampled values are voltages produced when said charging member is constant-current-controlled.
Claim 50
Dependent Claim
23 words
An apparatus according to Claim 46, wherein said charging member is constant-voltage-controlled with the voltage determined by said determining means, during transfer operation.
Claim 51
Dependent Claim
24 words
An apparatus according to Claim 45, wherein said detecting means detects the sample values, while the recording material is absent in a transfer position.
Claim 52
Dependent Claim
27 words
An apparatus according to Claim 43, wherein detection of the sample values in the first mode is continued until the sample values is within a predetermined range.
Claim 53
Dependent Claim
37 words
An apparatus according to Claim 43, wherein a voltage to be applied to said charging member during the image forming operation is determined on the basis of an average of sample values detected in the second mode.
Claim 54
Dependent Claim
51 words
An apparatus according to Claim 53, wherein said charging member is a rotatable member, and wherein the voltage to be applied to said charging member during the image forming operation is determined on the basis of an average of the sampled values obtained from one full rotation of said charging member.
Claim 55
Independent Claim
45 words
An apparatus according to Claims 43, 52, 53 and 54, wherein an operation of the first mode is carried out before printing operation on the recording material, and an operation of the second mode is carried out in the printing operation on the recording material.
Claim 56
Dependent Claim
29 words
An apparatus according to Claim 43, wherein a detecting period of one sample value by said detecting means is shorter in the first mode than in the second mode.
Claim 57
Dependent Claim
33 words
An apparatus according to Claim 43, wherein said image forming means forms a toner image on the recording material, and the voltage and the currents have the same polarity as the toner image.
Claim 58
Dependent Claim
57 words
An image forming apparatus or a method in which an image bearing member is charged by a charging member which is fed with electric power from electric power source, in which the electric power source is controlled so as to provide a constant electric current which is not related to the impedance of the image forming apparatus.
Claim 59
Dependent Claim
36 words
Image apparatus including a contact or close gap type charger, in which the electrical supply to the charger is controlled so as to reduce the effects on the charging current of the resistance of the charger.
Claim 60
Dependent Claim
49 words
A charging apparatus comprising means for controlling the electrical charging of a charger, characterised by means for measuring signals providing an indication of resistance of a component within a system of which the charger forms a part, and means for charging in accordance with the results of the measurements.
Claim 61
Dependent Claim
42 words
A voltage source for a charger which comprises means for storing a plurality of different voltage/current relationships, means for sensing electrical parameters of a system including the charger, and means for selecting one of the relationships in accordance with the sensed parameters.
Claim 62
Dependent Claim
41 words
A charger for image forming apparatus which comprises an electric power source, and control means for performing an initial measurement of current or voltage and for setting the electrical supply during subsequent image forming operations in accordance with the initial measurement.
References Cited (Backward Citations)
No citation records indexed.
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