Development apparatus having an extended development nip

A development apparatus for moving magnetic developer material into development contact with a latent image on an image-bearing surface that is movable along a fixed path in an electrostatographic reproduction apparatus, the magnetic development apparatus comprising:

• (a) a housing including a development opening for location adjacent the fixed path of the image-bearing surface;
• (b) means for containing and moving magnetic developer material within said housing;
• and
• (c) a magnetic development brush for forming a development nip with the image-bearing surface along a suitable segment of the fixed path of the image-bearing surface, and for transporting a magnetic developer material nap from within said housing through said development nip such that the development material nap contacts and develops latent images on the image-bearing surface, the magnetic development brush comprising:
• (i) a rotatable magnetic core having alternating pole magnets, each said magnet of said core generating a first magnetic field having a first magnetic strength region;
• (ii) a stationary non-magnetic shell surrounding said magnetic core, said non-magnetic shell having a first portion located within said first magnetic strength region of said first magnetic field, and a second portion associated with said development opening for forming a development nip with the image-bearing surface, said second portion including an extended shoulder section for increasing the width of said development nip into a second region beyond said first magnetic strength region of said first magnetic field, said shoulder section being locatable along and spaced from said suitable segment of the fixed path of the image-bearing surface, and said shoulder section having a surface contoured to follow said fixed path of the image-bearing surface within said suitable segment thereof;
• and
• (iii) a magnetizable material mounted to lie within said first magnetic strength region of said first magnetic field and within said extended shoulder section, said magnetizable material due to said first magnetic field forming a field magnet, and generating a second auxiliary magnetic field for enhancing and increasing the magnetic field strength of a resultant magnetic field at and about said shoulder section, thereby enabling the continued forming of a magnetic developer material nap having a desired consistency and thickness around said shoulder section of said second portion of the non-magnetic shell.

A development apparatus for developing latent images using developer material having magnetic carrier particles, the developer apparatus comprising:

• (a) a housing;
• (b) a magnetic development brush having (i) a rotatable magnetic core generating a first magnetic field for holding and moving magnetic developer material on said magnetic brush;
• and (ii) a stationary non-magnetic shell surrounding said magnetic core for forming a development nip with an image-bearing surface, said non-magnetic shell being shaped to conform to the contour of the image-bearing surface from an entrance side to an exit side of said development nip;
• and said non-magnetic shell having outwardly projecting portions at said entrance and exit sides of said development nip;
• and
• (c) a magnetizable member mounted inside said non-magnetic shell within at least one of said outwardly projecting portions at said entrance and exit sides of said development nip for enhancing the magnetic strengths of said first magnetic field within and about said at least one outwardly projecting portion of said shell.