Electrographic recording method and apparatus with control of toner quantity at recording region

Electrographic apparatus for use with dry, magnetically attractable, electronically conductive toner including:

• a receptor recording member;
• first and second electrode means in spaced opposing relationship with said receptor recording member spaced from said first electrode, wherein said first electrode means is stationary, to provide a recording region between said receptor recording member and said first electrode and adapted for making electronic contact with said second electrode, said receptor recording member adapted for movement relative to said first electrode means, said first electrode means including means for providing a magnetic field at said recording region that is concentrated at said first electrode;
• means for supplying the toner to said recording region in a regular and uniform manner whereby the toner when supplied to said recording region, is attracted toward said first electrode means by said magnetic field causing said toner to span the space between said first electrode means and said receptor recording member to establish an electronically conductive path via the toner between said first electrode and said receptor recording member;
• means adapted to apply recording electrical potential signals to said first electrode relative to said second electrode concurrent with movement of said receptor recording member relative to said first electrode means for causing some of the toner at said recording region to be held on said receptor recording member as toner images;
• force producing means for providing a temporally relative constant force acting on the toner when presented to said recording region to remove a portion of the toner from said recording region and from electronic contact with toner in said recording region for maintaining a constant quantity of toner in said recording region, the toner removed from said recording region by said force producing means being toner that accumulates in excess of said constant quantity due to changes in the amount of toner supplied to said recording region and the amount of toner held on said receptor recording member as toner images.

An electrographic method for producing a toner image at the surface of a receptor recording member using dry, magnetically attractable, electronically conductive toner including the steps of arranging first and second electrodes in spaced opposed relationship, wherein said first electrode is stationary, with a receptor recording member interposed and spaced from said first electrode with electronic contact provided between said receptor recording member and said second electrode while providing movement of said receptor recording member relative to said first electrode as the toner is supplied in a regular or relatively uniform manner to the region between said first electrode and said receptor recording member while a temporally relative constant force is provided which acts on the toner to cause the toner to span the space between said first electrode and said receptor recording member causing the toner to provide an electronically conductive path between said first electrode and said second electrode;

• applying recording electrode potential signals to said first electrode relative to said second electrode, while said movement of said receptor recording member relative to said first electrode is provided, causing toner to be held to said recording receptor member in accordance with signals to produce a toner image;
• and
• providing a temporally relatively constant force which acts on the toner in the region between said first electrode and said receptor recording member for removing a portion of the toner from said region and out of electronic contact with the toner in said region for maintaining a constant quantity of toner in said region, the toner removed from said region being toner that accumulates in excess of said constant quantity due to changes in the amount of toner supplied to said region and the amount of toner held on said receptor recording member as toner images.