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US 5,491,541 AGranted
Developing apparatus having adjacent similar magnetic poles
AssigneeMinolta Camera Kabushiki Kaisha
InventorsTomoaki Yokoyama, Makoto Takase
Life of this patent
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AssigneeMinolta Camera Kabushiki Kaisha
InventorsTomoaki Yokoyama, Makoto Takase
Estimating the term…
The present invention is characterized in that two magnetic poles of a magnetic member which are positioned to confront a nipping region between a sleeve and a photoreceptor in neighboring relation with each other are of the same polarity. These neighboring poles of the same polarity produce a distribution of magnetic flux density having first and second local maximum points and a local minimum point therebetween. A central angle .theta.1 between a line extending from a center of the magnetic member to the first local maximum point and a line extending the center to the local minimum point is smaller than a central angle .theta.2 between the line extending from the center to the local minimum point and a line extending from the center to the second local maximum point. Further, a developer material retained by the magnetic force of attraction generated by the neighboring magnetic poles of same polarity are kept in contact with the electorostatic latent image bearing member.
A developing apparatus comprising a stationary magnetic member having a plurality of magnetic poles extending in a direction axially of the magnetic member, and a non-magnetic rotatable sleeve enclosing the magnetic member therein, wherein a developer material is retained upon a periphery of the sleeve by effect of a magnetic force of attraction generated by the magnetic member during a rotation of the sleeve so as to be brought into contact with an electrostatic latent bearing member, two of the magnetic poles of the magnetic member which are positioned so as to confront a nipping region between the sleeve and a photoreceptor in neighboring relation with each other are of same polarity, and produce a distribution of magnetic flux density having a local minimum point, a first local maximum point located upstream of the local minimum point with respect to rotation of the sleeve, and a second local maximum point located downstream of the local minimum point with respect to the rotation of the sleeve, a central angle .theta.1 between a line extending from a center of the magnetic member to the first local maximum point and a line extending from the center of the magnetic member to the local minimum point being smaller than a central angle .theta.2 between the line extending from the center of the magnetic member to the local minimum point and a line extending from the center of the magnetic member to the second local maximum point;
A developing apparatus comprising a stationary magnetic member having a plurality of magnetic poles extending in a direction axially of the magnetic member, and a non-magnetic rotatable sleeve enclosing the magnetic member therein, wherein a developer material is retained upon a periphery of the sleeve by effect of a magnetic force of attraction generated by the magnetic member during a rotation of the sleeve so as to be brought into contact with an electrostatic latent bearing member, two of the magnetic poles of the magnetic member which are positioned so as to confront a nipping region between the sleeve and a photoreceptor in neighboring relation with each other are of same polarity, and produce a distribution of magnetic flux density having a local minimum point, a first local maximum point located upstream of the local minimum point with respect to rotation of the sleeve, and a second local maximum point located downstream of the local minimum point with respect to the rotation of the sleeve, a difference between a maximum flux density of the first local magnetic point and that of the local minimum point being equal to or more than 200 gauss and a rate of change of magnetic flux density from said local minimum point to said second local maximum point being equal to or less than 10 gauss/degree;
A developing apparatus comprising a stationary magnetic member having a plurality of magnetic poles extending in a direction axially of the magnetic member, and a non-magnetic rotatable sleeve enclosing the magnetic member therein, wherein a developer material is retained upon a periphery of the sleeve by effect of a magnetic force of attraction generated by the magnetic member during a rotation of the sleeve so as to be brought into contact with an electrostatic latent bearing member, two of the magnetic poles of the magnetic member which are positioned so as to confront a nipping region between the sleeve and a photoreceptor in neighboring relation with each other are of same polarity, and produce a distribution of magnetic flux density having a local minimum point, a first local maximum point located upstream side of the local minimum point with respect to the rotation of the sleeve, and a second local maximum point located downstream side of the local minimum point with respect to the rotation of the sleeve, magnetic flux densities of the first and second local maximum points and local minimum point have a following relation below:
Dependencies are inferred from the claim text.