Method and means for reducing frame effect in electrographic images on microfiche

Claim 2

An electrographic recording system comprising: A. means for impressing an electrostatic charge on the frame area of an electrographic storage medium; B. means for exposing an image area within said frame area to a light image of an original so that the image area is smaller than the frame area, thereby forming a non-illuminated, charged boundary around the image area, said exposing means comprising a non-electrically conductive ring extending opposite said boundary, said ring (1.) establishing the focal plane of the exposing means, (2.) providing a seal against toner particles around the edge of the frame area, and (3.) masking the storage medium along said boundary from incident light; and C. means for directing toner particles along the surface of the medium with an appreciable velocity so that their momentums across the medium surface inhibit their tendency to be captured by the residual charge on fully exposed portions of the medium whereby they collect at the unexposed or only partially exposed portions of the image area and at said charged boundary so as to improve the quality of the image on the medium while simultaneously forming a sharp, distinct, uniform dark border around and touching the image area on the medium.

Claim 3

An electrographic recording system comprising: A. means for impressing an electrostatic charge on a frame area of an electrographic storage medium; B. means for exposing an image area within said frame area to a light image of a message source, or original, so that the image area is smaller than the frame area, said exposing means comprising means along the optical path from the original image to the medium for establishing an aperture shaped and arranged so that a light image of a message source, or original, is incident on a portion of the storage medium having an area which is less than the frame area and whose shape is similar to that of the frame area, thereby forming a non-illuminated, charged boundary around the image area,; C. means for applying toner particles to the frame area, said charged boundary inhibiting the tendency of excess toner particles to be captured by the residual charge on fully exposed portions of the medium whereby they collect at the unexposed or only partially exposed portions of the image area and at said charged boundary, so as to improve the quality of the image on the medium while simultaneously forming a sharp, distinct, uniform dark border around and touching the image area on the medium; and D. means for confining the toner particles to the frame area so as not to prevent use of other portions of the medium for other frame areas.

Claim 4

An electrographic recording system comprising: A. means for impressing an electrostatic charge on a frame area of an electrographic storage medium; B. means for exposing an image area within said frame area to a light image of a message source, or original, so that the image area is smaller than the frame area, said exposing means comprising means along the optical path from the original image to the medium for establishing an aperture shaped and arranged so that a light image of a message source, or original, is incident on a portion of the storage medium having an area which is less than the frame area and whose shape is similar to that of the frame area, thereby forming a non-illuminated, charged boundary around the image area,; C. means for applying toner particles to the frame area, said charged boundary inhibiting the tendency of excess toner particles to be captured by the residual charge on fully exposed portions of the medium whereby they collect at the unexposed or only partially exposed portions of the image area and at said charged boundary, so as to improve the quality of the image on the medium while simultaneously forming a sharp, distinct, uniform dark border around and touching the image area on the medium; and D. means for confining the toner particles to the frame area so as not to prevent use of other portions of the medium for other frame areas.

Claim 5

An electrographic recording system for copying a message source, or original, on a fiche comprising: A. means for impressing an electrostatic charge on a frame area of a fiche electrographic storage medium, wherein the frame area is only a small part of the fiche area; B. means for exposing an image area within said frame area to a light image of a message source, thereby forming a non-illuminated, charged boundary in the frame area, around and in direct contact with the image area; C. means for confining the toner particles to the frame area, whereby they collect at the unexposed or only partially exposed portions of the image area and at said charged boundary so as to improve the quality of the image on the medium while simultaneously forming a sharp, distinct, uniform dark border around and touching the image area on the medium and permitting other portions of the fiche arbitrarily close to such border to be used for other frame areas.

Claim 6

An electrographic recording system for copying a message source, or original, on a fiche comprising: A. means for impressing an electrostatic charge on a frame area of a fiche electrographic storage medium, wherein the frame area is only a small part of the fiche area; B. means for exposing an image area within said frame area to a light image of a message source, thereby forming a non-illuminated, charged boundary in the frame area, around and in direct contact with the image area; C. means for confining the toner particles to the frame area, whereby they collect at the unexposed or only partially exposed portions of the image area and at said charged boundary so as to improve the quality of the image on the medium while simultaneously forming a sharp, distinct, uniform dark border around and touching the image area on the medium and permitting other portions of the fiche arbitrarily close to such border to be used for other frame areas.

Claim 7

The electrographic recording system of claim 3 further including means for directing toner particles along the surface of the medium with an appreciable velocity so that their momentums across the medium surface inhibit their tendency to be captured by the residual charge on fully exposed portions of the medium.

Claim 8

The electrographic recording system of either claim 3 or claim 4, wherein the means for exposing an image area has a focal length such that the image of the message source is projected onto a portion of the fiche whose area is less than and wholly within the frame area.

Claim 9

An electrographic recording system of claim 3 wherein the means for exposing an image area further includes a non-electrically conductive ring extending opposite said boundary, said ring A. establishing the focal plane of the exposing means, B. providing a seal against toner particles around the edge of the frame area, and C. masking the storage medium along said boundary from incident light.

Claim 12

The method of recording an image on a fiche type electrographic storage medium according to claim 17 wherein the step of exposing an image area comprises placing a mask along the optical path between the message source and the storage medium for establishing an aperture shaped and arranged so that a light image of the message source is incident on the storage medium and has an area which is less than the frame area and a shape similar to that of the frame area.

Claim 13

The method of claim 7 further including the steps of: A. flowing toner particles as a liquid along the surface of the medium with an appreciable velocity so that their momentums across the medium surface inhibit their tendency to be captured by the residual charge on fully exposed portions of the medium, whereby they tend to collect on unexposed or only partially exposed portions of the image area and at said charged boundary thereby improving the image on the medium and forming a narrow distinctive border around and in direct contact with the image area; and B. controlling the rate of flow of toner across the medium surface in accordance with the background charge characteristic of the medium being recorded on.

Claim 14

The method of claim 9 further including, as part of the exposing step, positioning the storage medium relative to the source so that the focal plane of the image is coincident with the storage medium and the area of the image at the focal plane is less than the frame area.

Claim 19

The method defined in claim 12 and further including the step of fixing the toner applied to the medium.