Magnetic brush developing apparatus

A magnetic brush developing apparatus comprising:

• a development container for containing a developer;
• a magnet stationarily located in said development container and having magnetic poles radially provided on a plurality of points thereof;
• a rotational sleeve arranged so as to cover an outer circumference of said magnet and rotatably driven to carry the developer in said development container to an image carrying body;
• a developer restriction member arranged opposite to said rotational sleeve to restrict an amount of the developer carried by said rotational sleeve;
• two of said magnetic poles being a developing magnetic pole facing opposite to said image carrying body and a developer transfer magnetic pole located between said developing magnetic pole and said developer restriction member;
• a magnetic brush of said developer formed on said rotational sleeve by said developer transfer magnetic pole having a magnetic flux density, a half value width of said magnetic flux density of said developer transfer magnetic pole being determined such that said developer at a tip of said magnetic brush is prevented from separating and flying away due to a centrifugal force of an arc caused by rotation of said rotational sleeve, wherein an angle between a crest cutting point of said developer restriction member and a closest point of said image carrying body with said rotational sleeve is approximately 90.degree. and said half value width of magnetic flux density of said developer carrying magnetic pole is more than 28.degree..

A magnetic brush developing apparatus comprising:

• a development container for containing a developer;
• a magnet fixed in said development container and having magnetic poles radially provided on a plurality of points thereof;
• a rotational sleeve arranged so as to cover an outer circumference of said magnet and rotatably driven to carry the developer in said development container to an image carrying body;
• a developer restriction member arranged opposite to said rotational sleeve to restrict the amount of the developer carried by said rotational sleeve;
• two of said magnetic poles being a developing magnetic pole facing opposite to said image carrying body and a developer transfer magnetic pole located between said developing magnetic pole and said developer restriction member;
• a magnetic brush of said developer formed on said rotational sleeve by said developer transfer magnetic pole having a magnetic flux density, a half value width of said magnetic flux density of said developer transfer magnetic pole being determined such that said developer at a tip of said magnetic brush is prevented from separating and flying away due to a centrifugal force of an arc caused by rotation of said rotational sleeve;
• a uniform magnetic flux density section, where a radial component of the magnetic flux density is substantially uniform, being formed on a periphery of said rotational sleeve;
• and
• said developer restriction member located at a position facing said rotational sleeve arranged opposite to said uniform magnetic flux density section.

A magnetic brush developing apparatus comprising:

• a development container for containing a developer;
• a magnet fixed in said development container and having magnetic poles radially provided on a plurality of points thereof;
• a rotational sleeve arranged so as to cover an outer circumference of said magnet and rotatably driven to carry the developer in said development container to an image carrying body;
• a developer restriction member arranged opposite to said rotational sleeve to restrict the amount of the developer carried by said rotational sleeve;
• two of said magnetic poles being a developing magnetic pole facing opposite to said image carrying body and a developer transfer magnetic pole located between said developing magnetic pole and said developer restriction member;
• a magnetic brush of said developer formed on said rotational sleeve by said developer transfer magnetic pole having a magnetic flux density, a half value with of said magnetic flux density of said developer transfer magnetic pole being determined such that said developer at a tip of said magnetic brush is prevented from separating and flying away due to a centrifugal force of an arc caused by rotation of said rotational sleeve;
• a uniform magnetic flux density section, where a radial component of the magnetic flux density is substantially uniform, being formed on a periphery of said rotational sleeve;
• and
• said developer restriction member located at a position facing said rotational sleeve arranged opposite to said uniform magnetic flux density section, wherein said uniform magnetic flux density section is provided on both sides of a developer restriction member facing point therebetween so as to extend by an angle of at least 10 degrees each in terms of a rotational angle of said rotational sleeve.

A magnetic brush developing apparatus comprising:

• a development container for containing a developer;
• a magnet fixed in said development container and having magnetic poles radially provided on a plurality of points thereof;
• a rotational sleeve arranged so as to cover an outer circumference of said magnet and rotatably driven to carry the developer in said development container to an image carrying body;
• a developer restriction member arranged opposite to said rotational sleeve to restrict the amount of the developer carried by said rotational sleeve.;
• two of said magnetic poles being a developing magnetic pole facing opposite to said image carrying body and a developer transfer magnetic pole located between said developing magnetic pole and said developer restriction member;
• a magnetic brush of said developer formed on said rotational sleeve by said developer transfer magnetic pole having a magnetic flux density, a half value width of said magnetic flux density of said developer transfer magnetic pole being determined such that said developer at a tip of said magnetic brush is prevented from separating and flying away due to a centrifugal force of an arc caused by rotation of said rotational sleeve:
• a uniform magnetic flux density section, where a radial component of the magnetic flux density is substantially uniform, being formed on a periphery of said rotational sleeve;
• and
• said developer restriction member located at a position facing said rotational sleeve arranged opposite to said uniform magnetic flux density section, wherein said uniform magnetic flux density section has a vertical magnetic flux density lying within the range of .+-.10% with respect to a preset value for a developer restriction member facing point.

A magnetic brush developing apparatus comprising:

• a development container for containing a developer;
• a magnet fixed in said development container and having magnetic poles radially provided on a plurality of points thereof;
• a rotational sleeve arranged so as to cover an outer circumference of said magnet and rotatably driven to carry the developer in said development container to an image carrying body;
• a developer restriction member arranged opposite to said rotational sleeve to restrict the amount of the developer carried by said rotational sleeve;
• two of said magnetic poles being a developing magnetic pole facing opposite to said image carrying body and a developer transfer magnetic pole located between said developing magnetic pole and said developer restriction member;
• a magnetic brush of said developer formed on said rotational sleeve by said developer transfer magnetic pole having a magnetic flux density, a half value width of said magnetic flux density of said developer transfer magnetic pole being determined such that said developer at a tip of said magnetic brush is prevented from separating and flying away due to a centrifugal force of an arc caused by rotation of said rotational sleeve;
• a uniform magnetic flux density section, where a radial component of the magnetic flux density is substantially uniform, being formed on a periphery of said rotational sleeve;
• and
• said developer restriction member located at a position facing said rotational sleeve arranged opposite to said uniform magnetic flux density section, wherein said uniform magnetic flux density section is provided on both sides of a developer restriction member facing point therebetween so as to extend by an angle of at least 3 degrees in terms of a rotation angle of said rotational sleeve, and said uniform magnetic flux density sections has a vertical magnetic flux density lying within the range of .+-.20% with respect to a preset value for said developer restriction member facing point.

A magnetic brush developing apparatus comprising:

• a development container for containing a developer;
• a magnet fixed in said development container and having magnetic poles radially provided on a plurality of points thereof;
• a rotational sleeve arranged so as to cover an outer circumference of said magnet and rotatably driven to carry the developer in said development container to an image carrying body;
• a developer restriction member arranged opposite to said rotational sleeve to restrict the amount of the developer carried by said rotational sleeve;
• two of said magnetic poles being a developing magnetic pole facing opposite to said image carrying body and a developer transfer magnetic pole located between said developing magnetic pole and said developer restriction member;
• a magnetic brush of said developer formed on said rotational sleeve by said developer transfer magnetic pole having a magnetic flux density, a half value width of said magnetic flux density of said developer transfer magnetic pole being determined such that said developer at a tip of said magnetic brush is prevented from separating and flying away due to a centrifugal force of an arc caused by rotation of said rotational sleeve;
• a uniform magnetic flux density section, where a radial component of the magnetic flux density is substantially uniform, being formed on a periphery of said rotational sleeve;
• and
• said developer restriction member located at a position facing said rotational sleeve arranged opposite to said uniform magnetic flux density section, wherein said uniform magnetic flux density section is provided on both sides of a developer restriction member facing point therebetween so as to extend by an angle of at least 3 degrees in terms of a rotation angle of said rotational sleeve, and said uniform magnetic flux density sections has a vertical magnetic flux density lying within the range of .+-.10% with respect to a preset value for said developer restriction member facing point.

A magnetic brush developing apparatus comprising:

• a development container for containing a developer;
• a magnet fixed in said development container and having magnetic poles radially provided on a plurality of points thereof;
• a rotational sleeve arranged so as to cover an outer circumference of said magnet and rotatably driven to carry the developer in said development container to an image carrying body;
• a developer restriction member arranged opposite to said rotational sleeve to restrict the amount of the developer carried by said rotational sleeve;
• two of said magnetic poles being a developing magnetic pole facing opposite to said image carrying body and a developer transfer magnetic pole located between said developing magnetic pole and said developer restriction member;
• a magnetic brush of said developer formed on said rotational sleeve by said developer transfer magnetic pole having a magnetic flux density, a half value width of said magnetic flux density of said developer transfer magnetic pole being determined such that said developer at a tip of said magnetic brush is prevented from separating and flying away due to a centrifugal force of an arc caused by rotation of said rotational sleeve;
• a uniform magnetic flux density section, where a radial component of the magnetic flux density is substantially uniform, being formed on a periphery of said rotational sleeve;
• and
• said developer restriction member located at a position facing said rotational sleeve arranged opposite to said uniform magnetic flux density section, wherein said uniform magnetic flux density section is provided on both sides of a developer restriction member facing point therebetween so as to extend by an angle of at least 10 degree in terms of a rotation angle of said rotational sleeve, and said uniform magnetic flux density sections has a vertical magnetic flux density lying within the range of .+-.20% with respect to a preset value for said developer restriction member facing point.

A magnetic brush developing apparatus comprising:

• a development container for containing a developer;
• a magnet fixed in said development container and having magnetic poles radially provided on a plurality of points thereof;
• a rotational sleeve arranged so as to cover an outer circumference of said magnet and rotatably driven to carry the developer in said development container to an image carrying body;
• a developer restriction member arranged opposite to said rotational sleeve to restrict the amount of the developer carried by said rotational sleeve;
• two of said magnetic poles being a developing magnetic pole facing opposite to said image carrying body and a developer transfer magnetic pole located between said developing magnetic pole and said developer restriction member;
• a magnetic brush of said developer formed on said rotational sleeve by said developer transfer magnetic pole having a magnetic flux density, a half value width of said magnetic flux density of said developer transfer magnetic pole being determined such that said developer at a tip of said magnetic brush is prevented from separating and flying away due to a centrifugal force of an arc caused by rotation of said rotational sleeve;
• a uniform magnetic flux density section, where a radial component of the magnetic flux density is substantially uniform, being formed on a periphery of said rotational sleeve;
• and
• said developer restriction member located at a position facing said rotational sleeve arranged opposite to said uniform magnetic flux density section, wherein said uniform magnetic flux density section is provided on both sides of a developer restriction member facing point therebetween so as to extend by an angle of at least 5 degree in terms of a rotation angle of said rotational sleeve, and said uniform magnetic flux density sections has a vertical magnetic flux density lying within the range of .+-.15% with respect to a preset value for said developer restriction member facing point.