Patent EP0509441A2 successfully refreshed from Google Patents.
EP0509441A2
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EP
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Electrophotographic method and apparatus
Assignee: Panasonic Holdings Corp
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Filing: 1992-04-14
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Granted: —
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Expires: 2012-04-14
Abstract
Abstract An electrophotographic apparatus including a photoreceptor drum (18) supported for rotation in one direction sequentially past a plurality of processing stations, a corona charger (20) for electrostatically charging the photoreceptor drum (18), a developer hopper (22) accommodating therein a mass of developing material (25) used to form a visible toner image and a transfer charger (28) for transferring the toner image onto a recording paper. The developer hopper (22) has its bottom portion formed with an opening open so as to accommodate a portion of the photoreceptor drum (18) so that the developing material (25) can be electrostatically deposited on the photoreceptor drum (18) including both non-image and image areas to form a toner layer. The apparatus also includes an electrode member (26) operable to electrostatically remove a portion of the toner layer covering the non-image area, thereby leaving the remaining portion of the toner layer in the image area to form the visible toner image. An electrophotographic method practised by the apparatus is also disclosed.
Inventors
- 👤 Hajime Yamamoto
- 👤 Hiroshi Terada
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 07:30
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/06; G03G15/08; G03G15/09; G03G15/095; G03G2215/00; G03G2215/06; G03G2215/0602; G03G2215/0604; G03G2215/0614; G03G2215/0621; G03G2215/0634; G03G2215/0636; G03G2215/0639
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
149 words
An electrophotographic method which comprises the steps of: moving an electrostatic latent image carrier, having a stationary magnet enclosed therein, so as to pass through a developer reservoir containing a mass of magnetic developing material therein thereby to deposit the magnetic developing material on a surface of the latent image carrier; and removing a portion of the magnetic developing material from the surface of the latent image carrier while being positioned between an electrode roll spaced from the latent image carrier with a gap defined between the electrode roll and the latent image carrier; wherein a force acting to remove that portion of the magnetic developing material from the latent image carrier during the removing step is a composite force consisting of a magnetic force connecting between the latent image carrier and the electrode roll and an electrostatic force connecting between the latent image carrier and the electrode roll.
Claim 2
Dependent Claim
144 words
An electrophotographic method which comprises the steps of: moving an electrostatic latent image carrier, having a first stationary magnet enclosed therein, so as to pass through a developer reservoir containing a mass of magnetic developing material therein thereby to cause the magnetic developing material to be magnetically deposited on a surface of the latent image carrier; and removing a portion of the magnetic developing material from the surface of the latent image carrier while being positioned between an electrode roll spaced from the latent image carrier with a gap defined between the electrode roll and the latent image carrier, said electrode roll including a second magnet of a polarity opposite to that of the first magnet, said removing step being carried out by applying an alternating current voltage to said electrode roll so that that portion of the magnetic developing material can be recovered.
Claim 3
Dependent Claim
147 words
An electrophotographic method which comprises the steps of: moving an electrostatic latent image carrier, having a stationary magnet enclosed therein, so as to cause the latent image carrier to be sequentially charged; forming an electrostatic latent image; passing the latent image carrier through a developer reservoir, containing a mass of magnetic developing material therein, so as to cause the developing material to be magnetically deposited on a surface of the latent image carrier: reversal developing the electrostatic latent image by positioning it so as to confront an electrode roll to which a voltage is applied, said electrode roll being spaced from the latent image carrier with a gap defined between the electrode roll and the latent image carrier, said voltage being applied to said electrode roll at a timing simultaneous with a passage of a charged area of the latent image carrier through said reversal developing step.
Claim 4
Dependent Claim
97 words
The method as claimed in Claim 3, wherein the voltage applied to the electrode roll is an alternating current voltage superimposed with a direct current voltage and wherein the alternating current voltage superimposed with the direct current voltage, which does not develop the latent image carrier is applied during the passage of a non-charged area of the latent image carrier, but the alternating current voltage superimposed with the direct current voltage, which is suited to accomplish a development of the latent image carrier is applied during the passage of the charged area of the latent image carrier.
Claim 5
Dependent Claim
121 words
An electrophotographic apparatus which comprises: a movably supported electrostatic latent image carrier including a stationary magnet enclosed therein; a supply means for supplying magnetic developing material onto a surface of the latent image carrier; an electrode roll spaced from the latent image carrier with a gap defined between it and a surface of the latent image carrier and positioned so as to confront the stationary magnet inside the latent image carrier, said electrode roll being supported for rotation in a direction counter to a direction of rotation of the latent image carrier; and a voltage applying means for applying to the electrode roll a voltage necessary to remove toner on a non-image area of the surface of the latent image carrier.
Claim 6
Dependent Claim
16 words
The apparatus as claimed in Claim 5, wherein said electrode roll is made of magnetic material.
Claim 7
Dependent Claim
25 words
The apparatus as claimed in Claim 6, wherein said electrode roll is made of non-magnetic material and includes a magnet disposed inside the electrode roll.
Claim 8
Dependent Claim
29 words
The apparatus as claimed in Claim 5, wherein said developing material is a two-component developing material comprising a mass of magnetic carrier particles and a mass of toner particles.
Claim 9
Dependent Claim
16 words
The apparatus as claimed in Claim 5, wherein said developing material is a one-component developing material.
Claim 10
Dependent Claim
160 words
An electrophotographic apparatus which comprises: a movably supported electrostatic latent image carrier having a first stationary magnet enclosed therein; a latent image forming means for forming an electrostatic latent image on the latent image carrier; a reservoir positioned adjacent a surface of the latent image carrier and accommodating a mass of magnetic developing material to be magnetically deposited on the latent image carrier by an effect of the stationary magnet; an electrode roll spaced from the latent image carrier with a gap defined between it and a surface of the latent image carrier and adapted to be applied with an alternating current voltage, said electrode roll including a second magnet being supported for rotation in a direction counter to a direction of rotation of the latent image carrier and positioned such that a pole of the first magnet inside the latent image carrier assumes a position upstream of a minimum distance between the latent image carrier and the electrode roll.
Claim 11
Dependent Claim
185 words
An electrophotographic apparatus which comprises: a movably supported electrostatic latent image carrier including a first stationary magnet enclosed therein; a latent image forming means for forming an electrostatic latent image on the latent image carrier; a developer reservoir positioned adjacent a surface of the latent image carrier and accommodating a mass of magnetic developing material to be magnetically deposited on the latent image carrier by an effect of the first magnet; and an electrode roll adapted to be applied with an alternating current voltage for removing toner deposited on an non-image area of the latent image carrier; said electrode roll being made of non-magnetic material and including a second magnet having a polarity opposite to that of the first magnet, the pole of said first magnet being positioned upstream of a minimum distance between the latent image carrier and the electrode roll while the pole of said second magnet is positioned downstream of the position of the minimum distance between the latent image carrier and the electrode roll, and said electrode roll being positioned spaced from the latent image carrier with a gap defined therebetween.
Claim 12
Dependent Claim
147 words
An electrophotographic apparatus which comprises: a movably supported electrostatic latent image carrier including a stationary magnet enclosed therein; a latent image forming means for forming an electrostatic latent image on the latent image carrier; a developer reservoir positioned adjacent a surface of the latent image carrier and accommodating a mass of magnetic developing material to be magnetically deposited on the latent image carrier by an effect of the first magnet; and a movably supported electrode roll adapted to be applied with an alternating current voltage for removing toner deposited on an non-image area of the latent image carrier, said electrode roll being positioned spaced from the latent image carrier with a gap defined therebetween for movement in a direction counter to a direction of movement of the latent image carrier at a speed equal to or lower than a speed of movement of the latent image carrier.
Claim 13
Dependent Claim
152 words
An electrophotographic apparatus which comprises: a movably supported electrostatic latent image carrier having a stationary magnet enclosed therein; a charging means for charging the latent image carrier; a latent image forming means for forming an electrostatic latent image on the latent image carrier; a reservoir positioned adjacent a surface of the latent image carrier and accommodating a mass of magnetic developing material to be magnetically deposited on the latent image carrier by an effect of the stationary magnet; and an electrode roll spaced from the latent image carrier with a gap defined between it and the latent image carrier and adapted to be applied with an alternating current voltage to reversal develop the electrostatic latent image, wherein an area of the latent image carrier which is charged by the charging means has a width greater than that of an area of the latent image carrier which is magnetized by the stationary magnet.
Claim 14
Dependent Claim
156 words
An electrophotographic apparatus which comprises: a movably supported electrostatic latent image carrier having a stationary magnet enclosed therein; a latent image forming means for forming an electrostatic latent image on the latent image carrier; a reservoir positioned adjacent a surface of the latent image carrier and accommodating a mass of magnetic developing material to be magnetically deposited on the latent image carrier by an effect of the stationary magnet; and a movably supported electrode roll spaced from the latent image carrier with a gap defined between it and the latent image carrier and adapted to be applied with an alternating current voltage to reversal develop the electrostatic latent image, said electrode roll being supported for movement in a direction counter to a direction of movement of the latent image carrier, wherein a maximum magnetic flux density of the stationary magnet on a surface of the latent image carrier is equal to or higher than 300 gausses.
Claim 15
Dependent Claim
135 words
An electrophotographic apparatus which comprises: a movably supported electrostatic latent image carrier having a stationary magnet enclosed therein; a reservoir positioned adjacent a surface of the latent image carrier and accommodating a mass of magnetic developing material to be magnetically deposited on the latent image carrier by an effect of the stationary magnet, said reservoir having a confronting portion; and a rotatably supported electrode roll spaced from the latent image carrier with a gap defined between it and the latent image carrier and adapted to be applied with an alternating current voltage for recovering an unnecessary developing material from the latent image carrier, said confronting portion of the reservoir being having a width equal to or greater than 5mm as measured in a direction conforming to a direction of movement of the latent image carrier.
References Cited (Backward Citations)
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