Fine line print enhancement
AssigneeInternational Business Machines Corporation
InventorsLarry W. Bassetti, Sherwood Kantor
Life of this patent
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Abstract
This discloses an electrophotographic printing machine with circuits to enhance the printing of fine lines, such as lines of a single picture element (pel) in width. Provision is made for broadening such lines in one dimension by adding small "black" areas to each edge of the fine line in order to broaden it. In a second dimension, perpendicular to the first dimension, lines are broadened by placing gray pels next to black pels. The disclosure also discusses specific cases in which it may be considered desirable to inhibit the enhancement signals.
Claims36
An electrophotographic printing machine comprising:
- drive means;
- movable carrier means driven by said drive means;
- photoreceptive material mounted on said movable carrier means for cyclic movement through electrophotographic process stations;
- charge corona means located at a first station for placing a relatively uniform electrostatic charge on the surface of said photoreceptive material;
- exposure means located at a second station for selectively discharging the charged photoreceptive material to cause the formation of a latent image on said material;
- toner for developing said image;
- developer means located at a third station for applying said toner to said image to produce a developed image;
- image receiving material;
- transfer means located at a fourth station for transferring said developed image from said photoreceptive material to said image receiving material;
- paper storage means for holding a supply of image receiving material;
- a finishing station;
- paper forwarding means for serially moving image receiving material from said storage means through the transfer station to said finishing station;
- control means for operating said exposure means, said control means comprising:
- a character generator for producing data signals to drive said exposure means to produce the desired image on said photoreceptive material;
- and
- enhancement means for altering certain of said data signals before presentation of said signals to said exposure means to produce broadened image lines on said photoreceptor where said lines occur in either of two dimensions perpendicular to each other.
In a printing machine, imaging means for producing an image to be reproduced on work material, control means for operating said imaging means to create the desired pattern on said material, in accordance with image producing data signals, said control means including enhancement means for enhancing the print output of said printing machine by broadening fine lines occurring in either of two perpendicular directions.
A method for broadening the width of fine lines in a printed image produced by an electrophotographic printing machine, comprising the steps of:
- charging the photoreceptive material of said machine to a first charge level;
- utilizing exposure means to selectively discharge portions of said photoreceptive material;
- obtaining said selective discharge by modulating said exposure means to discharge said photoreceptive material to a second charge level by exposing said material in discrete picture elements in accordance with a stream of data signals;
- altering said stream of data signals in a first manner to produce expanded picture elements in a first dimension to broaden fine lines in said first dimension;
- and
- altering said stream of data signals in a second manner to produce an intermediate charge level on said photoreceptive material in picture elements directly adjacent fine line picture elements in a second dimension perpendicular to said first dimension.
In a method of enhancing the printing of fine lines by an electrophotographic printing machine which method includes a first group of steps to add gray picture elements directly adjacent picture elements defining a fine line in a first dimension, and includes a second group of steps to expand picture elements defining a fine line in a second dimension perpendicular to said first dimension, the improvement comprising the steps of:
- inhibiting the output signal of one of the groups of enhancement steps when an expanded picture element coincides with a gray picture element in the same picture element area.
In a method of enhancing the printing of fine lines by an electrophotographic printing machine which method includes a first group of steps to add gray picture elements directly adjacent picture elements defining a fine line in a first dimension, and includes a second group of steps to expand picture elements defining a fine line in a second dimension perpendicular to said first dimension, the improvement comprising the steps of:
- inhibiting the output signals of both groups of enhancement steps when two expanded picture elements coincide with a gray picture element in the same picture element area.
Dependencies are inferred from the claim text.