Magnet roll developing unit
AssigneeOlympus Optical Co., Ltd.
InventorMasaji Nishikawa
Life of this patent
Estimating the term…
Abstract
A developing unit comprises a guide vane mounted on a portion of the housing which defines a developing opening and disposed for contact with the free end of a developer brush which is formed by a conveying magnetic pole, and a vent formed in the housing at a location removed from the opening. The guide vane cooperates with the brush which moves during the rotation of a non-magnetic sleeve to provide an air pump action, which draws the air containing the toner in suspension into the closed housing of the developing unit from the region of the opening while the vent acts to reduce the internal air pressure within the housing which tends to increase as a result of the air pump action.
Claims14
A magnet roll developing unit comprising:
- a closed housing containing a magnetic developer which includes a magnetic powder and a toner and having a developing opening formed therein at a location opposite to a surface to be developed;
- a magnet roll fixedly mounted in the housing and carrying a developing magnetic pole and a plurality of conveying magnetic poles, said developing pole being disposed to be opposite to the surface to be developed through the developing opening;
- a cylindrical, non-magnetic sleeve disposed in surrounding relationship with the magnet roll and having its lower portion immersed in a quantity of magnetic developer whih is received in the housing, said sleeve being disposed for rotation in one direction so that the magnetic developer attracted thereon by the magnetic force from the conveying poles is conveyed thereon upwardly toward the developing opening and is formed into a first tuft-shaped developer brush in the region of the developing opening under the magnetic influence of the developing pole;
- a doctor blade for controlling the height of the magnetic developer layer formed and retained on the sleeve under the magnetic influence of the magnet roll as the developer enters into the developing opening;
- a guide vane mounted on a member which defines one end of the developing opening being disposed close to or for contact with the free end of a second tuft-shaped developer brush formed by the magnetic field of one of the conveying poles which is located next to the developing pole, as viewed in the direction of rotation of the sleeve, said last-mentioned one of said conveying poles being arranged across from said guide vane, the guide vane guiding all toner returned to said housing to move between said guide vane and said non-magnetic sleeve and cooperating with the moving second tuft-shaped developer brush to provide an air pump action which develops a suction condition on the side of the second tuft-shaped developer brush facing the surface to be developed to draw the air containing the toner in suspension in the region of the developing opening into the housing;
- the spacing between the sleeve and the guide vane causing the central portion of the second tuft-shaped developer brush to block the flow of air other than that contained in said second tuft-shaped developer brush to enhance the positiveness and effectiveness of the suction and pumping actions and to eliminate the need for additional air pumping means for said developer housing;
- a vent formed in the housing for reducing the internal air pressure within the housing which internal air pressure increases as a result of the air pump action, and in order to enhance the air pump action;
- and
- toner removal means for trapping the toner which is suspended in the effluent flow moving toward and through the vent.
Dependencies are inferred from the claim text.