Piece-wise printed image enhancement for dot matrix printers

Claim 3

A method according to claim 1 wherein the orientation and proportionality of each cell is controlled by: a. storing bits of digital data representative respectively of a plurality of image transitions having known characteristic curvatures such as smooth edge curves, sharp tips and notches; b. reading incoming digital data which may or may not be representative of said known characteristic curvatures; c. comparing read digital data with said stored digital data, and thereby d. converting only digital information which is representative of said known characteristic curvatures to said characteristic curvatures.

Claim 6

A method according to claim 3 which includes generating an error correction signal only where there is a correlation between said read data and said stored data.

Claim 7

A method according to claim 3 or 4 wherein the conversion of said digital information includes: a. reading an image transition to establish an initial pattern of cells to be printed, and b. controlling the orientation and ink proportionality of each cell to thereby rearrange said initial pattern to more closely follow the shape and contour of said image transition.

Claim 10

A method according to claim 6 characterised by the additional step of storing said plurality of predetermined matching patterns.

Claim 13

A system according to claim 8 wherein said means for controlling and rearranging includes: a. means for storing bits of digital data representative of a plurality of image transitions having known characteristic curvatures such as smooth edge curves, sharp tips and notches; b. means for reading incoming digital data which may or may not be representative of said known characteristic curvatures; and c. means connected to said storing means and to said reading means for comparing said incoming digital data and bits of stored digital data for thereby generating an error signal useful for converting incoming digital data representative of said known characteristic curvatures to said characteristic curvatures.

Claim 16

Apparatus for enhancing the displayed image produced by a display apparatus, said display apparatus including character generator means providing a bit data signal representative of a bit map image of a desired image and image display means responsive to said bit data signal to display said desired image, said apparatus characterised by: temporary storage means coupled to said character generator means temporarily storing portions of said bit data signal representing N number of consecutive bits in M number of consecutive lines of said bit map image forming an M x N subset of the bits defining said bit map image, a predetermined number of bits of said subset of bits forming a sample window having a predetermined shape defined by the matrix position of said bits, said sample window having a central bit; matching network means coupled to said temporary storage means for comparing the bit pattern formed by said central bit and the remaining, adjacent bits in said sample window with a plurality of predetermined error matching bit patterns, each of said matching bit patterns associated with one of a plurality of modification signals; and signal generating means coupled to said matching network means and to said image display means for generating an associated one of a plurality of predetermined modification signals if said sample window bit pattern matches at least one of said plurality of error matching bit patterns, said associated modification signal substituted for said central bit in said bit data signal, said image display means responsive to said modification signal to display a modified image element associated with said central bit.

Claim 17

Apparatus for enhancing the displayed image produced by a display apparatus, said display apparatus including character generator means providing a bit data signal representative of a bit map image of a desired image and image display means responsive to said bit data signal to display said desired image, said apparatus characterised by: temporary storage means coupled to said character generator means temporarily storing portions of said bit data signal representing N number of consecutive bits in M number of consecutive lines of said bit map image forming an M x N subset of the bits defining said bit map image, a predetermined number of bits of said subset of bits forming a sample window having a predetermined shape defined by the matrix position of said bits, said sample window having a central bit; matching network means coupled to said temporary storage means for comparing the bit pattern formed by said central bit and the remaining, adjacent bits in said sample window with a plurality of predetermined error matching bit patterns, each of said matching bit patterns associated with one of a plurality of modification signals; and signal generating means coupled to said matching network means and to said image display means for generating an associated one of a plurality of predetermined modification signals if said sample window bit pattern matches at least one of said plurality of error matching bit patterns, said associated modification signal substituted for said central bit in said bit data signal, said image display means responsive to said modification signal to display a modified image element associated with said central bit.

Claim 18

An apparatus according to claim 11 characterised by storage means for storing said plurality of predetermined matching bit patterns.

Claim 19

An apparatus according to claim 11 or 12 characterised in that said associated modification signal comprises a modulation bit stream having a total time duration as that of an unmodified bit in said bit data signal, said modulation bit stream modulating said image display means during said unmodified bit time duration to produce said modified image element.

Claim 20

An apparatus according to claim 11, 12 or 13 characterised in that said matching network means comprises a programmed logic array.

Claim 21

An electrophotographic printing machine comprising: rotatable drum means; a layer of photoconductive material mounted on the surface of said rotatable drum means for cyclic movement through electrophotographic process stations; charge corona means disposed adjacent said rotatable drum means for placing a substantially uniform electrostatic charge on the surface of said layer of photoconductive material; exposure means for selectively discharging said charged photoconductive material to cause the formation of a latent image on the surface of said photoconductive material; developer means disposed adjacent said rotatable drum means for applying toner to said latent image to produce a developed image; transfer means disposed adjacent said rotatable drum means for transferring said developed image from said photoconductive material to a print media; fusing means for fusing said toner to said print media; paper transfer means for serially moving said print media from a media storage means through said transfer means to said fusing means; control means for operating said exposure means; character generator means coupled to said control means to provide data signals representative of a desired image to be produced on said photoconductive material; characterised by enhancement means interposed between said control means and said character generator means for generating compensation signals to be substituted for selected ones of said data signals whereby an image produced from said substituted data signals is of an enhanced visual quality, said enhancement means comprising: temporary storage means coupled to said character generator means temporarily storing portions of said data signals forming a sample pattern representative of a portion of said desired image, said sample pattern having a central data signal; matching networks means coupled to said temporary storage means for comparing said sample pattern to a plurality of predetermined template patterns, each of said predetermined template patterns associated with one of a plurality of compensation signals; and signal generating means coupled to said matching network means for generating said associated one of said plurality of compensation signals if said sample pattern matches at least one of said predetermined template patterns said associated compensation signal substituted for said central data signal in said data signals.

Claim 22

An electrophotographic printing machine comprising: rotatable drum means; a layer of photoconductive material mounted on the surface of said rotatable drum means for cyclic movement through electrophotographic process stations; charge corona means disposed adjacent said rotatable drum means for placing a substantially uniform electrostatic charge on the surface of said layer of photoconductive material; exposure means for selectively discharging said charged photoconductive material to cause the formation of a latent image on the surface of said photoconductive material; developer means disposed adjacent said rotatable drum means for applying toner to said latent image to produce a developed image; transfer means disposed adjacent said rotatable drum means for transferring said developed image from said photoconductive material to a print media; fusing means for fusing said toner to said print media; paper transfer means for serially moving said print media from a media storage means through said transfer means to said fusing means; control means for operating said exposure means; character generator means coupled to said control means to provide data signals representative of a desired image to be produced on said photoconductive material; characterised by enhancement means interposed between said control means and said character generator means for generating compensation signals to be substituted for selected ones of said data signals whereby an image produced from said substituted data signals is of an enhanced visual quality, said enhancement means comprising: temporary storage means coupled to said character generator means temporarily storing portions of said data signals forming a sample pattern representative of a portion of said desired image, said sample pattern having a central data signal; matching networks means coupled to said temporary storage means for comparing said sample pattern to a plurality of predetermined template patterns, each of said predetermined template patterns associated with one of a plurality of compensation signals; and signal generating means coupled to said matching network means for generating said associated one of said plurality of compensation signals if said sample pattern matches at least one of said predetermined template patterns said associated compensation signal substituted for said central data signal in said data signals.

Claim 23

An electrophotographic printing machine according to claim 15 characterised in that said enhancement means further comprises storage means for storing said plurality of template patterns.

Claim 24

An electrophotographic printing machine according to claim 15 or 16 characterised in that said exposure means comprises a laser, said control means responsive to said data signals to generate laser drive signals turning said laser on and off to produce a modulated laser beam for selectively discharging said charged photoconductive material to cause the formation of said desired image, said control means responsive to said data signals to turn said laser on for a predetermined full signal time period, said control means responsive to said compensation signals to turn said laser on for a predetermined time period less than said full signal time period.

Claim 25

An electrophotographic printing machine according to claim 17 characterised in that each of said plurality of compensation signals comprises a different unique bit stream having a total time duration equal to said full signal time period and modulating said laser during said full signal time period to produce a desired compensation effect associated with said compensation signal.

Claim 26

An electrophotographic printing machine according to any of claims 15 to 18 characterised in that said temporary storage means comprises a plurality of clocked shift registers and counters defining a first-in-first-out data buffer.

Claim 27

An electrophotographic printing machine according to any of claims 15 to 19 characterised in that said matching network means comprises a programmed logic array for comparing said sample pattern to a plurality of predetermined template patterns.