EP0339673A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Device of toner image transfer for electrophotographic printing apparatus
Assignee: Toshiba Corp
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Filing: 1989-04-28
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Granted: —
•
Expires: 2009-04-28
Abstract
Abstract A method and device of toner image transfer for an electrophotographic printing apparatus capable of obtaining desired elasticity and the resistivity on the electrostatic toner transfer roller, such that the stable high quality images can be obtained regardless of the environmental conditions. The device includes transfer roller (5) having a multi-layer structure with an outermost resistive layer (1), a flexible conductive layer (2) to be inside and electrically connected to the resistive layer (1), and an elastically deformable elastic sponge rubber layer (3) inside the conductive layer (2). Related features concerning transfer roller cleaning, transfer bias voltage application, and toner control are also disclosed.
Inventors
- 👤 Yasuo Hosaka
- 👤 Tadayoshi Ohno
- 👤 Tsutomu Kanai
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 10:43
CPC Classifications
G; G03; G03G; G03G9/00; G03G9/08; G03G15/00; G03G15/06; G03G15/08; G03G15/09; G03G15/14; G03G15/16; G03G15/1665; G03G15/167; G03G15/1685
Claims Analysis
Total Claims: 72
Claim 1
Independent Claim
148 words
A transfer device for an electrophotographic printing apparatus, in which a toner image(8) formed by toner is to be transferred onto a receiving paper(9), comprising: photoconductive drum means(7) for carrying the toner image(8) formed in accordance with an electrostatic latent image formed thereon; transfer roller means(5) which makes contact with the photoconductive drum means(7) for effectuating the transfer of the toner image(8) onto the receiving paper(9), the receiving paper(9) being conveyed between the transfer roller means(5) and the photoconductive drum means(7); and transfer bias voltage source means(10) for applying a transfer bias voltage which causes the transfer of the toner image(8), to the transfer roller means(5); characterized in that the transfer roller means(5) includes: outermost resistive layer(1) which makes contact with the receiving paper(9); flexible conductive layer(2) to be inside and electrically connected to the resistive layer(1); and elastically deformable elastic sponge rubber layer(3) inside the conductive layer(2).
Claim 2
Dependent Claim
148 words
A transfer device for an electrophotographic printing apparatus, in which a toner image(8) formed by toner is to be transferred onto a receiving paper(9), comprising: photoconductive drum means(7) for carrying the toner image(8) formed in accordance with an electrostatic latent image formed thereon; transfer roller means(5) which makes contact with the photoconductive drum means(7) for effectuating the transfer of the toner image(8) onto the receiving paper(9), the receiving paper(9) being conveyed between the transfer roller means(5) and the photoconductive drum means(7); and transfer bias voltage source means(10) for applying a transfer bias voltage which causes the transfer of the toner image(8), to the transfer roller means(5); characterized in that the transfer roller means(5) includes: outermost resistive layer(1) which makes contact with the receiving paper(9); flexible conductive layer(2) to be inside and electrically connected to the resistive layer(1); and elastically deformable elastic sponge rubber layer(3) inside the conductive layer(2).
Claim 3
Dependent Claim
27 words
The device of claim 1, wherein the resistive layer(1) has a resistivity per unit area in a range of 1 × 10⁷ - 1 × 10¹⁰ Ω·cm².
Claim 4
Dependent Claim
27 words
The device of claim 2, wherein the resistive layer(1) has the resistivity per unit area in a range of 1 × 10⁸ - 5 × 10⁸ Ω·cm².
Claim 5
Dependent Claim
17 words
The device of claim 2, wherein the conductive layer(2) has a volume resistivity less than 10⁶ Ω·cm.
Claim 6
Dependent Claim
17 words
The device of claim 4, wherein the conductive layer(2) has the volume resistivity less than 10⁵ Ω·cm.
Claim 7
Dependent Claim
31 words
The device of claim 1, wherein the elastic sponge rubber layer(3) has a thickness not less than ten times a sum of thicknesses of the resistive layer(1) and the conductive layer(2).
Claim 8
Dependent Claim
18 words
The device of claim 1, wherein the elastic sponge rubber layer(3) has a thickness more than 2 mm.
Claim 9
Dependent Claim
50 words
The device of claim 1, wherein the elastic sponge rubber layer(3) has a rubber hardness less than that corresponding to 30 degree for Japanese Industrial Standard, and wherein the transfer roller means(5) makes contact with the photoconductive drum means(7) with a pressure in a range of 20 - 300 g/cm².
Claim 10
Dependent Claim
28 words
The device of claim 8, wherein the transfer roller means(5) makes contact with the photoconductive drum means(7) with a pressure in a range of 100 - 200 g/cm².
Claim 11
Dependent Claim
44 words
The device of claim 1, wherein the transfer roller means(5) further includes: metallic shaft(4) inside the elastic sponge rubber layer(3) to which the transfer bias voltage is applied; and elastically deformable elastic conductive portion(6a, 6b) electrically connecting the metallic shaft(4) and the conductive layer(2).
Claim 12
Dependent Claim
14 words
The device of claim 1, wherein the resistive layer(1) has a resin sheet structure.
Claim 13
Dependent Claim
16 words
The device of claim 1, wherein the elastic sponge rubber layer(3) has a continuous foam structure.
Claim 14
Dependent Claim
26 words
The device of claim 1, wherein the transfer roller means(5) further comprises a conductive rubber layer(12) between the conductive layer(2) and the elastic sponge rubber layer(3).
Claim 15
Dependent Claim
21 words
The device of claim 1, wherein a surface of the transfer roller means(5) has no concavity deeper than 12 µm depth.
Claim 16
Dependent Claim
21 words
The device of claim 14, wherein a surface of the transfer roller means(5) has no concavity deeper than 5 µm depth.
Claim 17
Dependent Claim
21 words
The device of claim 1, wherein a surface of the transfer roller means(5) has no waving deeper than 20 µm depth.
Claim 18
Dependent Claim
51 words
The device of claim 1, wherein the transfer roller means(5) further includes extended member(1 / 13a, 13b) having a resistivity not less than that of the resistive layer(1), extending in a direction along axis of rotation of the transfer roller means(5), to be longer in this direction than the conductive layer(2).
Claim 19
Dependent Claim
44 words
The device of claim 17, wherein the extended member(1 / 13a, 13b) is longer in the direction along axis of rotation of the transfer roller means(5) than the conductive layer(2) by a length in a range of 0.5 - 5 mm at both ends.
Claim 20
Dependent Claim
19 words
The device of claim 1, wherein the resistive layer(1) has a resistivity which decreases as atmospheric vapor pressure increases.
Claim 21
Dependent Claim
48 words
The device of claim 19, wherein the resistivity of the resistive layer(1) times a thickness of the resistive layer(1) takes a value in a range of 1 × 10⁷ - 1 × 10⁹ Ω·cm² when the atmospheric vapor pressure is in a range of 10 - 40 mb.
Claim 22
Dependent Claim
14 words
The device of claim 19, wherein the resistive layer(1) is made of vinylidene fluoride.
Claim 23
Dependent Claim
61 words
The device of claim 1, further comprising incompressible and insulative guiding ring means(18a, 18b) having contact with the photoconductive drum means(7) and to be attached on sides of the transfer roller means(5), for intermediating rotational motion of the photoconductive drum means(7) to the transfer roller means(5), the guide ring means(18a, 18b) having radius less than that of the transfer roller means(5).
Claim 24
Dependent Claim
29 words
The device of claim 22, wherein the radius of the guide ring means(18a, 18b) is less than that of the transfer roller means(5) by no more than 300 µm.
Claim 25
Dependent Claim
29 words
The device of claim 23, wherein the radius of the guide ring means(18a, 18b) is less than that of the transfer roller means(5) by no more than 150 µm.
Claim 26
Dependent Claim
22 words
The device of claim 1, wherein the transfer bias voltage source means(10 / 30) applies the transfer bias voltage in pulsed form.
Claim 27
Dependent Claim
25 words
The device of claim 25, wherein the pulsed form transfer bias voltage has a pulse width in a range between 0.2 sec and 4 µsec.
Claim 28
Dependent Claim
25 words
The device of claim 26, wherein the pulsed form transfer bias voltage has a pulse width in a range between 20 msec and 1 msec.
Claim 29
Dependent Claim
48 words
The device of claim 25, wherein the pulsed form transfer bias voltage pulsates at least twice during a time in which a point on the receiving paper(9 / 28) passes through the contact area between the transfer roller means(5 / 29) and the photoconductive drum means(7 / 21).
Claim 30
Dependent Claim
24 words
The device of claim 25, wherein the transfer bias voltage source means(10 / 30) is equipped with a variable resister(35) protection against current overflow.
Claim 31
Dependent Claim
23 words
The device of claim 25, wherein the pulsed form transfer bias voltage is obtained as an AC voltage biased by a DC voltage.
Claim 32
Dependent Claim
101 words
The device of claim 1, further comprising: control charger means(36) located around the transfer roller means(5 / 29) for charging up the toner on the transfer roller means(5 / 29); and cleaning device(33) located around the photoconductive drum means(7 / 21) for removing the toner on the photoconductive drum means(7 / 21) after the transferring; and wherein the transferring is followed by a roller cleaning in which toner on the transfer roller means(5 / 29) is charged up by the control charger means (36), and then the transfer bias voltage is applied by the transfer bias voltage source means(10 / 30).
Claim 33
Dependent Claim
130 words
The device of claim 1, further comprising: main charger means(22) for charging up the photoconductive drum means; control charger means(36) located around the transfer roller means(5 / 29) for charging up the toner on the transfer roller means(5 / 29); and cleaning device(33) located around the photoconductive drum means(7 / 21) for removing the toner on the photoconductive drum means(7 / 21) after the transferring; and wherein the transferring is followed by a roller cleaning in which toner on the transfer roller means(5 / 29) is charged up by the control charger(36), and the photoconductive drum means(7 / 21) is charged up by the main charger means(22) such that the potential level of the photoconductive drum means(7 / 21) is lower than that of the transfer roller means(5 / 29).
Claim 34
Dependent Claim
85 words
The device of claim 1, further comprising transfer roller cleaning blade means(40) making contact with surface of the transfer roller means(5 / 29), for cleaning the toner on the transfer roller means(5 / 29), the blade means(40) having a pivot arranged to be in a side closer to the transfer roller means(5 / 29) with respect to a tangent line of the surface of the transfer roller means(5 / 29) at location where the blade means(40) makes contact with the transfer roller means(5 / 29).
Claim 35
Dependent Claim
45 words
The device of claim 33, wherein the pivot of the blade means(40) is located ahead in a direction of rotation of the transfer roller means(5 / 29), with respect to the location where the blade means(40) makes contact with the transfer roller means(5 / 29)
Claim 36
Dependent Claim
34 words
The device of claim 33, wherein the blade means(40) having a supporting member(43) which is not straight, and wherein the blade means(40) is given a pressure against the transfer roller means(5 / 29) externally.
Claim 37
Dependent Claim
44 words
The device of claim 33, wherein a line pressure between the transfer roller means(5 / 29) and the blade means(40) is less than that between the transfer roller means(5 / 29) and the photoconductive drum means(7 / 21) by no less than 5 g/cm.
Claim 38
Dependent Claim
29 words
The device of claim 33, wherein a line pressure between the transfer roller means(5 / 29) and the blade means(40) is in a range of 10 - 35 g/cm.
Claim 39
Dependent Claim
61 words
The device of claim 1, further comprising: developing means(26) for supplying toner to the electrostatic latent image on the photoconductive drum means(7 / 21); sensor means(80) for detecting area to be given the toner from the developing means(26); and toner control means(81) for controlling the developing means(26) such that toner is supplied only to those area detected by the sensor means(80).
Claim 40
Dependent Claim
44 words
The device of claim 38, further comprising transfer control means(81) for controlling the transfer bias voltage source means(10 / 30) such that the transfer bias voltage is applied only when the area with the toner given comes to the transfer roller means(5 / 29).
Claim 41
Dependent Claim
54 words
The device of claim 39, wherein the control by the transfer control means(81) is such that the transfer bias voltage application begins after a front edge of the receiving paper(9 / 28) moved a prescribed distance from a contact point between the transfer roller means(5 / 29) and the photoconductive drum means(7 / 21).
Claim 42
Dependent Claim
88 words
The device of claim 39, wherein the control by the transfer control means(81) is such that the transfer bias voltage is increased from zero before a front edge of the receiving paper(9 / 28) reaches a contact point between the transfer roller means(5 / 29) and the photoconductive drum means(7 / 21) to a non-zero value after the front edge of the receiving paper(9 / 28) moved a prescribed distance from the contact point between the transfer roller means(5 / 29) and the photoconductive drum means(7 / 21).
Claim 43
Dependent Claim
52 words
The device of claim 38, wherein the developing means(26) includes rotatable magnet roller means(88) for making localized pile of the toner(89), and wherein the toner control means(81) controls the magnet roller means(88) such that a distance between the localized pile of the toner(89) and the photoconductive drum means(7 / 21) is changed.
Claim 44
Dependent Claim
57 words
The device of claim 38, wherein the developing means(26) includes sleeve(87) from which the toner is supplied and leveling blade means(90) located around the sleeve(87) for limiting amount of the toner on the sleeve(87), and wherein the toner control means(81) controls the leveling blade means(90) such that the amount of the toner on the sleeve(87) is changed.
Claim 45
Dependent Claim
45 words
The device of claim 43, wherein the developing means(26) further includes selective bias voltage means(91) for applying selected bias voltage to the sleeve(87), and wherein toner control means(81) also controls the selective bias voltage means(91) such that the potential level of the sleeve(87) is changed.
Claim 46
Dependent Claim
137 words
A transfer device for an electrophotographic printing apparatus, in which a toner image(8) formed by a toner is to be transferred onto a receiving paper(9), comprising: photoconductive drum means(7) for carrying the toner image(8) formed in accordance with an electrostatic latent image formed thereon; transfer roller means(5) which makes contact with the photoconductive drum means(7) for effectuating the transfer of the toner image(8) onto the receiving paper(9), the receiving paper(9) being conveyed between the transfer roller means(5) and the photoconductive drum means(7); and transfer bias voltage source means(10) for applying a transfer bias voltage which causes the transfer of the toner image(8), to the transfer roller means; characterized in that the transfer roller means(5) having an outer surface which makes contact with the receiving paper(9) and which has a resistivity which decreases as atmospheric vapor pressure increases.
Claim 47
Dependent Claim
137 words
A transfer device for an electrophotographic printing apparatus, in which a toner image(8) formed by a toner is to be transferred onto a receiving paper(9), comprising: photoconductive drum means(7) for carrying the toner image(8) formed in accordance with an electrostatic latent image formed thereon; transfer roller means(5) which makes contact with the photoconductive drum means(7) for effectuating the transfer of the toner image(8) onto the receiving paper(9), the receiving paper(9) being conveyed between the transfer roller means(5) and the photoconductive drum means(7); and transfer bias voltage source means(10) for applying a transfer bias voltage which causes the transfer of the toner image(8), to the transfer roller means; characterized in that the transfer roller means(5) having an outer surface which makes contact with the receiving paper(9) and which has a resistivity which decreases as atmospheric vapor pressure increases.
Claim 48
Independent Claim
97 words
A method of toner image transfer for an electrophotographic printing apparatus, in which a toner image(8) formed by a toner is to be transferred onto a receiving paper(9), comprising the steps of: forming an electrostatic latent image on an photoconductive drum(7); developing the electrostatic latent image by toner to obtain a toner image(8); transferring the toner image(8) onto the receiving paper(9) by conveying the receiving paper(9) to a transfer area, and by applying a transfer bias voltage to the receiving paper(9); characterized in that at the transferring step the transfer bias voltage is applied in pulsed form.
Claim 49
Independent Claim
97 words
A method of toner image transfer for an electrophotographic printing apparatus, in which a toner image(8) formed by a toner is to be transferred onto a receiving paper(9), comprising the steps of: forming an electrostatic latent image on an photoconductive drum(7); developing the electrostatic latent image by toner to obtain a toner image(8); transferring the toner image(8) onto the receiving paper(9) by conveying the receiving paper(9) to a transfer area, and by applying a transfer bias voltage to the receiving paper(9); characterized in that at the transferring step the transfer bias voltage is applied in pulsed form.
Claim 50
Dependent Claim
25 words
The method of claim 46, wherein the pulsed form transfer bias voltage has a pulse width in a range between 0.2 sec and 4 µsec.
Claim 51
Dependent Claim
25 words
The method of claim 47, wherein the pulsed form transfer bias voltage has a pulse width in a range between 20 msec and 1 msec.
Claim 52
Dependent Claim
32 words
The method of claim 46, wherein the pulsed form transfer bias voltage pulsates at least twice during a time in which a point on the receiving paper(9) passes through the transfer area.
Claim 53
Dependent Claim
27 words
The method of claim 46, wherein the transfer bias voltage is applied by a transfer bias voltage source equipped with a variable resister protection against current overflow.
Claim 54
Dependent Claim
23 words
The method of claim 46, wherein the pulsed form transfer bias voltage is obtained as an AC voltage biased by a DC voltage.
Claim 55
Dependent Claim
168 words
A transfer device for an electrophotographic printing apparatus, in which a toner image formed by a toner is to be transferred onto a receiving paper(28), comprising: photoconductive drum means(21) for carrying the toner image formed in accordance with an electrostatic latent image formed thereon; transfer roller means(29) which makes contact with the photoconductive drum means(21) for effectuating the transfer of the toner image onto the receiving paper(28), the receiving paper(28) being conveyed between the transfer roller means(29) and the photoconductive drum means(21); transfer bias voltage source means(30) for applying a transfer bias voltage which causes the transfer of the toner image, to the transfer roller means(29); and developing means(26) for supplying toner to the electrostatic latent image on the photoconductive drum means(21); characterized by further comprising: sensor means(80) for detecting an area on the photoconductive drum means(21) to be given toner from the developing means(26); and toner control means(81) for controlling the developing means(26) such that toner is supplied only to those area detected by the sensor means(80).
Claim 56
Dependent Claim
168 words
A transfer device for an electrophotographic printing apparatus, in which a toner image formed by a toner is to be transferred onto a receiving paper(28), comprising: photoconductive drum means(21) for carrying the toner image formed in accordance with an electrostatic latent image formed thereon; transfer roller means(29) which makes contact with the photoconductive drum means(21) for effectuating the transfer of the toner image onto the receiving paper(28), the receiving paper(28) being conveyed between the transfer roller means(29) and the photoconductive drum means(21); transfer bias voltage source means(30) for applying a transfer bias voltage which causes the transfer of the toner image, to the transfer roller means(29); and developing means(26) for supplying toner to the electrostatic latent image on the photoconductive drum means(21); characterized by further comprising: sensor means(80) for detecting an area on the photoconductive drum means(21) to be given toner from the developing means(26); and toner control means(81) for controlling the developing means(26) such that toner is supplied only to those area detected by the sensor means(80).
Claim 57
Dependent Claim
39 words
The device of claim 52, further comprising transfer control means(81) for controlling the transfer bias voltage source means(30) such that the transfer bias voltage is applied only when the area with toner given comes to the transfer roller means(29).
Claim 58
Dependent Claim
48 words
The device of claim 53, wherein the control by the transfer control means(81) is such that the transfer bias voltage application begins after a front edge of the receiving paper(28) moved a prescribed distance from a contact point between the transfer roller means(29) and the photoconductive drum means(21).
Claim 59
Dependent Claim
76 words
The device of claim 53, wherein the control by the transfer control means(81) is such that the transfer bias voltage is increased from zero before a front edge of the receiving paper(28) reaches a contact point between the transfer roller means(29) and the photoconductive drum means(21) to a non-zero value after the front edge of the receiving paper(28) moved a prescribed distance from the contact point between the transfer roller means(29) and the photoconductive drum means(21).
Claim 60
Dependent Claim
50 words
The device of claim 53, wherein the developing means(26) includes rotatable magnet roller means(88) for making localized pile of the toner(89), and wherein the toner control means(81) controls the magnet roller means(88) such that a distance between the localized pile of the toner(89) and the photoconductive drum means(21) is changed.
Claim 61
Dependent Claim
57 words
The device of claim 52, wherein the developing means(26) includes sleeve(87) from which the toner is supplied and leveling blade means(90) located around the sleeve(87) for limiting amount of the toner on the sleeve(87), and wherein the toner control means(81) controls the leveling blade means(90) such that the amount of the toner on the sleeve(87) is changed.
Claim 62
Dependent Claim
45 words
The device of claim 57, wherein the developing means(26) further includes selective bias voltage means(91) for applying selected bias voltage to the sleeve(87), and wherein toner control means(81) also controls the selective bias voltage means(91) such that the potential level of the sleeve(87) is changed.
Claim 63
Independent Claim
125 words
A method of toner image transfer for an electrophotographic printing apparatus, in which a toner image formed by toner is to be transferred onto a receiving paper(28), comprising the steps of: forming an electrostatic latent image on an photoconductive drum(21); developing the electrostatic latent image by toner to obtain a toner image; and transferring the toner image onto the receiving paper(28) by conveying the receiving paper(28) to a transfer area, and by applying a transfer bias voltage to the receiving paper(28); characterized by further comprising the steps of: detecting an area on the photoconductive drum(21) to be given the toner from the developing means(26); and characterized in that at the developing step only the detected area is developed by toner to obtain a toner image.
Claim 64
Independent Claim
125 words
A method of toner image transfer for an electrophotographic printing apparatus, in which a toner image formed by toner is to be transferred onto a receiving paper(28), comprising the steps of: forming an electrostatic latent image on an photoconductive drum(21); developing the electrostatic latent image by toner to obtain a toner image; and transferring the toner image onto the receiving paper(28) by conveying the receiving paper(28) to a transfer area, and by applying a transfer bias voltage to the receiving paper(28); characterized by further comprising the steps of: detecting an area on the photoconductive drum(21) to be given the toner from the developing means(26); and characterized in that at the developing step only the detected area is developed by toner to obtain a toner image.
Claim 65
Dependent Claim
28 words
The method of claim 59, wherein at the transferring step the transfer bias voltage is applied only when the area with toner given comes to the transfer area.
Claim 66
Dependent Claim
32 words
The method of claim 60, wherein at the transferring step the transfer bias voltage application begins after a front edge of the receiving paper(28) moved a prescribed distance from the transfer area.
Claim 67
Dependent Claim
50 words
The method of claim 60, wherein at the transferring step the transfer bias voltage is increased from zero before a front edge of the receiving paper(28) reaches the transfer area to a non-zero value after the front edge of the receiving paper moved a prescribed distance from the transfer area.
Claim 68
Dependent Claim
40 words
The method of claim 59, wherein at the developing step, rotatable magnet roller means(88) for making localized pile of the toner(89) is controlled such that a distance between the localized pile of the toner(89) and the photoconductive drum(21) is changed.
Claim 69
Dependent Claim
40 words
The method of claim 59, wherein at the developing step, leveling blade means(90) located around a sleeve(87) for limiting amount of the toner on the sleeve(87) is controlled such that the amount of the toner on the sleeve(87) is changed.
Claim 70
Dependent Claim
34 words
The device of claim 64, wherein at the developing step, selective bias voltage means(91) for applying selected bias voltage to the sleeve(87) is controlled such that the potential level of the sleeve(87) is changed.
Claim 71
Dependent Claim
73 words
The device of claim 1, further comprising: developing means(26) for supplying toner to the electrostatic latent image on the photoconductive drum means(7 / 21); and bias voltage means(25) for giving bias voltage to the developing means(26) such that the residual toner left on the photoconductive drum means(7 / 21) from previous printing which is not on new latent image formed on the photoconductive drum means(7 / 21) is attracted toward the developing means(26).
Claim 72
Dependent Claim
52 words
The device of claim 66, wherein the developing means(26) includes a developing roller(70) having a positive sleeve portion(74) and a negative portion(72), and wherein the bias voltage means(25) includes a positive bias voltage source(75) connected to the positive sleeve portion(74) and a negative bias voltage source(73) connected to the negative sleeve portion(72).
References Cited (Backward Citations)
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