US5363178A
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Image forming apparatus
Assignee: Canon Inc
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Filing: 1992-10-08
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Granted: 1994-11-08
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Expires: 2012-10-08
Abstract
Abstract An image forming apparatus, particularly a color image forming apparatus. A conveyer belt made of dielectric material is charged-up electrically by repetitive image transfer actions using corona charging. By the charge-up the transfer current decreases with the result of decrease of image density. In order to compensate with this, the average charge amount of the toner particles transferred to the image receiving material at later stage or stages of the repetitive image transfer actions is decreased with respect to the average charge amount of the toner particles transferred onto the image receiving material in the initial stage or stages of the repetitive image transfer actions. By doing so, the toner image densities in the respective colors are made uniform, so that sharp images can be produced.
Inventors
- 👤 Kenichi Matsumoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 00:34
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/01; G03G15/0142; G03G15/0178; G03G15/0194; G03G13/00; G03G13/01; G03G13/013; G03G13/0133; G03G9/00; G03G9/08; G03G9/10; G03G9/113; G03G2215/00; G03G2215/01; G03G2215/0103; G03G2215/0119; G03G2215/0151; G03G2215/0164
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
208 words
An image forming apparatus, comprising: image bearing means; means for forming latent images on said image bearing means; a plurality of developing means for developing the latent images formed by said image forming means with different color toner particles into toner images, each of said plurality of developing means includes a developer containing said different color toner particles and carrier particles; an image receiving material carrying means for carrying an image receiving material thereon; and transfer means for sequentially effecting image transfer operations for respective colors to transfer electrostatically the different color toner images from said image bearing means to the same image receiving material carried on said image receiving material carrying means wherein the image receiving material carried on said image receiving material carrying means is subjected to the image transfer operation of said transfer means a plurality of times; wherein the carrier particles used with the toner particles transferred in the initial stage or stages of the sequential image transfer operations are coated with surface coating resin having an uncured component content less than the carrier particles used with the toner particles in the later stage or stages of the sequential image transfer operations so as to control an average charge amount of the toner particles.
Claim 2
Dependent Claim
208 words
An image forming apparatus, comprising: image bearing means; means for forming latent images on said image bearing means; a plurality of developing means for developing the latent images formed by said image forming means with different color toner particles into toner images, each of said plurality of developing means includes a developer containing said different color toner particles and carrier particles; an image receiving material carrying means for carrying an image receiving material thereon; and transfer means for sequentially effecting image transfer operations for respective colors to transfer electrostatically the different color toner images from said image bearing means to the same image receiving material carried on said image receiving material carrying means wherein the image receiving material carried on said image receiving material carrying means is subjected to the image transfer operation of said transfer means a plurality of times; wherein the carrier particles used with the toner particles transferred in the initial stage or stages of the sequential image transfer operations are coated with surface coating resin having an uncured component content less than the carrier particles used with the toner particles in the later stage or stages of the sequential image transfer operations so as to control an average charge amount of the toner particles.
Claim 3
Dependent Claim
25 words
An apparatus according to claim 1, wherein the average charge amount of the toner particles is decreased with processing of the sequential image transfer operations.
Claim 4
Dependent Claim
20 words
An apparatus according to claim 1, wherein said carrying means includes a dielectric member for carrying the image receiving material.
Claim 5
Dependent Claim
17 words
An apparatus according to claim 1, 2 or 3, wherein said transfer means has corona discharging means.
Claim 6
Dependent Claim
15 words
An apparatus according to claim 3, wherein said conveying means electrostatically attracts the transfer material.
Claim 7
Dependent Claim
26 words
An apparatus according to claim 1 or 3, wherein said transfer means has a plurality of transfer stations at different positions relative to said carrying means.
Claim 8
Dependent Claim
22 words
An apparatus according to claim 6, wherein each of the transfer stations includes respective image bearing means and respective image transfer means.
Claim 9
Dependent Claim
19 words
An apparatus according to claim 7, wherein the respective image transfer means have substantially the same image transfer conditions.
Claim 10
Dependent Claim
18 words
An apparatus according to claim 8, wherein the respective image transfer means all have the same total currents.
Claim 11
Dependent Claim
24 words
An apparatus according to claim 3, wherein plural toner images are superposedly transferred from said image bearing means to the same image receiving material.
Claim 12
Dependent Claim
15 words
An apparatus according to claim 10, wherein said apparatus is a full-color image forming apparatus.
Claim 13
Dependent Claim
21 words
An apparatus according to claim 3, wherein said transfer means is opposed to said image bearing member through the dielectric member.
Claim 14
Dependent Claim
84 words
An apparatus according to claim 1, wherein an average charge amount of the toner particles per unit weight thereof at an initial stage or stages of the sequential image transfer operations is larger than an average charge amount of the toner particles per unit weight thereof at a later stage or stages of the sequential image transfer operations, and wherein the average charge amount of the toner particles at said later stage does not exceed the average charge amount of the immediately preceding stage.
Claim 15
Dependent Claim
30 words
An apparatus according to claim 1, wherein said developing means contains the toner particles charged to a polarity which is the same as a charging polarity of the latent image.
Claim 16
Dependent Claim
23 words
An apparatus according to claim 1, wherein the average change amount at the initial stage is larger than that at any later stage.
Claim 17
Dependent Claim
39 words
An apparatus according to claim 1, wherein four different color toners including a black toner, are used, and in the case the four color toners are transferred on a same image receiving material, the black toner is transferred last.
Claim 18
Dependent Claim
198 words
An image forming apparatus, comprising: image bearing means; means for forming latent images on said image bearing means; a plurality of developing means for developing the latent images formed by said image forming means with different color toner particles, having respective average charge amounts per unit weight, into toner images; an image receiving material carrying means for carrying an image receiving material thereon; and means for sequentially effecting image transfer operations for respective colors by transferring electrostatically the different color toner images from said image bearing means to the same image receiving material carried on said image receiving material carrying means; wherein said average charge amounts of the toner particles are set throughout the image transfer operations for the same image receiving material whereby a charge amount of said image receiving material carrying means in one of the image transfer operations for the same image receiving material is larger than a charge amount in another of the image transfer operations for the same image receiving material if the average charge amount of the toner particles to be transferred in said one of the image transfer operations is smaller than a charge amount in said another image transfer operations.
Claim 19
Dependent Claim
198 words
An image forming apparatus, comprising: image bearing means; means for forming latent images on said image bearing means; a plurality of developing means for developing the latent images formed by said image forming means with different color toner particles, having respective average charge amounts per unit weight, into toner images; an image receiving material carrying means for carrying an image receiving material thereon; and means for sequentially effecting image transfer operations for respective colors by transferring electrostatically the different color toner images from said image bearing means to the same image receiving material carried on said image receiving material carrying means; wherein said average charge amounts of the toner particles are set throughout the image transfer operations for the same image receiving material whereby a charge amount of said image receiving material carrying means in one of the image transfer operations for the same image receiving material is larger than a charge amount in another of the image transfer operations for the same image receiving material if the average charge amount of the toner particles to be transferred in said one of the image transfer operations is smaller than a charge amount in said another image transfer operations.
Claim 20
Dependent Claim
25 words
An apparatus according to claim 17, wherein the average charge amount of the toner particles is decreased with processing of the sequential image transfer operations.
Claim 21
Dependent Claim
20 words
An apparatus according to claim 17, wherein said carrying means includes a dielectric member for carrying the image receiving material.
Claim 22
Dependent Claim
15 words
An apparatus according to claim 19, wherein said carrying means electrostatically attracts the transfer material.
Claim 23
Dependent Claim
24 words
An apparatus according to claim 17, wherein said transfer means has a plurality of transfer stations at different positions relative to said carrying means.
Claim 24
Dependent Claim
22 words
An apparatus according to claim 21, wherein each of the transfer stations includes respective image bearing means and respective image transfer means.
Claim 25
Dependent Claim
34 words
An apparatus according to claim 17, wherein the image receiving material carried on said image receiving material carrying means is subjected to the image transfer operation of said transfer means a plurality of times.
Claim 26
Dependent Claim
84 words
An apparatus according to claim 23, wherein an average charge amount of the toner particles per unit weight thereof at an initial stage or stages of the sequential image transfer operations is larger than an average charge amount of the toner particles per unit weight thereof at a later stage or stages of the sequential image transfer operations, and wherein the average charge amount of the toner particles at said later stage does not exceed the average charge amount of the immediately preceding stage.
Claim 27
Dependent Claim
84 words
An apparatus according to claim 18, wherein an average charge amount of the toner particles per unit weight thereof at an initial stage or stages of the sequential image transfer operations is larger than an average charge amount of the toner particles per unit weight thereof at a later stage or stages of the sequential image transfer operations, and wherein the average charge amount of the toner particles at said later stage does not exceed the average charge amount of the immediately preceding stage.
Claim 28
Dependent Claim
15 words
An apparatus according to claim 23, wherein said apparatus is a full-color image forming apparatus.
Claim 29
Dependent Claim
23 words
An apparatus according to claim 17, wherein each of said plurality of developing means includes a developer containing toner particles and carrier particles.
Claim 30
Dependent Claim
49 words
An apparatus according to claim 27, wherein the carrier particles used with the toner particles transferred in the initial stage or stages are coated with surface coating resin having an uncured component content less than the carrier particles used with the toner particles in the later stage or stages.
Claim 31
Dependent Claim
18 words
An apparatus according to claim 17, wherein the respective image transfer means all have the same total currents.
Claim 32
Dependent Claim
39 words
An apparatus according to claim 17, wherein four different color toners including a black toner, are used, and in the case the four color toners are transferred on a same image receiving material, the black toner is transferred last.
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