US5109283A — Raster scanning engine driver which independently…

Claim 1

Independent Claim 122 words

A raster print engine driver for generating, from incoming data representative of an image, a transition-modulated engine drive signal for causing a print engine to reproduce the image as a series of modulated print lines, comprising: means for establishing a cell scan time period representing a horizontal length along a print line of an elemental cell print area; and means for generating from the incoming data in said cell scan time period two independently located drive signal transitions to cause the print engine to change state at selected points along the print lines for closely reproducing the image said generating means also enabling a state of non-transition wherein no drive signal transition is produced to cause said print engine to change state.

Claim 2

Dependent Claim 122 words

A raster print engine driver for generating, from incoming data representative of an image, a transition-modulated engine drive signal for causing a print engine to reproduce the image as a series of modulated print lines, comprising: means for establishing a cell scan time period representing a horizontal length along a print line of an elemental cell print area; and means for generating from the incoming data in said cell scan time period two independently located drive signal transitions to cause the print engine to change state at selected points along the print lines for closely reproducing the image said generating means also enabling a state of non-transition wherein no drive signal transition is produced to cause said print engine to change state.

Claim 3

Dependent Claim 29 words

The print engine driver of claim 1 in which said drive signal transitions are locatable with a precision of at least one sixty-fourth of said cell scan time period.

Claim 4

Dependent Claim 30 words

The print engine driver of claim 2 in which said drive signal transitions are locatable with a precision of approximately one two hundred fifty-sixth of said cell scan time period.

Claim 5

Dependent Claim 23 words

The print engine driver of claim 3 in which said cell print area is approximately one one hundred fiftieth of an inch long.

Claim 6

Dependent Claim 39 words

The print engine driver of claim 1 in which said print engine driver generates one of the cases of zero, one and two independently located drive signal transitions and the case of a third drive signal transition per cell.

Claim 7

Dependent Claim 33 words

The print engine driver of claim 1 in which said means for establishing a cell scan time period provides variable cell scan times to permit cell width scaling for changing an image size.

Claim 8

Dependent Claim 25 words

The print engine driver of claim 1 in which said means for generating includes a digital clock for providing clock signals having a clock period.

Claim 9

Dependent Claim 39 words

The print engine driver of claim 7 in which said means for generating further includes a plurality of delay means for generating from said clock signal a plurality of sequentially spaced clock phase signals having leading and trailing edges.

Claim 10

Dependent Claim 38 words

The print engine driver of claim 8 in which said means for generating further includes logic circuit means for generating, from said clock phase signals and the incoming data, drive signal transitions independently locatable within a clocking period.

Claim 11

Dependent Claim 23 words

The print engine driver of claim 9 in which said logic circuit means includes a digital counter for producing a digital ramp signal.

Claim 12

Dependent Claim 40 words

The print engine driver of claim 10 in which said logic circuit means further includes means for comparing the incoming data to said digital ramp signal to establish a drive signal transition time window within said cell scan time period.

Claim 13

Dependent Claim 39 words

The print engine driver of claim 11 in which said logic circuit means further includes means for selecting with the incoming data one of said clock phase signals to resolve a drive signal transition time within the established window.

Claim 14

Dependent Claim 36 words

The print engine driver of claim 12 in which said means for selecting includes means for choosing the leading or trailing edge of the selected clock phase signal to fully define the drive signal transition time.

Claim 15

Dependent Claim 26 words

The print engine driver of claim 9 in which at least one said delay means is accomplished with a propagation delay within said logic circuit means.

Claim 16

Dependent Claim 36 words

The print engine driver of claim 11 in which said means for establishing a cell scan time period includes means for providing variable cell scan times to permit cell width scaling for changing the image size.

Claim 17

Dependent Claim 51 words

The print engine driver of claim 15 in which said means for providing variable cell scan times includes means for resetting and restarting said digital ramp signal when said digital ramp signal reaches a selected value to end one cell scan time period and begin a next cell scan time period.

Claim 18

Dependent Claim 22 words

The print engine driver or claim 11 in which paid digital ramp is generated in gray code to prevent momentary false comparisons.

Claim 19

Dependent Claim 24 words

The print engine driver of claim 10 further including means for synchronizing the engine drive signal to the raster print engine horizontal synchronization signal.

Claim 20

Dependent Claim 26 words

The print engine driver of claim 18 in which said means for synchronizing includes means for resetting said digital counter at a horizontal synchronization signal time.

Claim 21

Dependent Claim 24 words

The print engine driver of claim 1 in which the incoming data is a digital representation of an image of text or line art.

Claim 22

Dependent Claim 32 words

The print engine driver of claim 20 in which said means for generating includes means for reproducing by drive signal transition placement the amount of image darkness within each cell print area.

Claim 23

Dependent Claim 36 words

The print engine driver of claim 21 in which said means for generating includes means for reproducing by drive signal transition placement the horizontal center of gravity of the image darkness within each cell print area.

Claim 24

Dependent Claim 19 words

The print engine driver of claim 22 in which at least some of said cell print areas overlap vertically.

Claim 25

Dependent Claim 28 words

The print engine driver of c aim 23 in which the image darkness in the cell print area overlapping areas are reproduced in both overlapping cell print areas.

Claim 26

Dependent Claim 28 words

The print engine driver of c aim 23 in which the image darkness in the cell print area overlapping areas are reproduced in both overlapping cell print areas.

Claim 27

Dependent Claim 28 words

The print engine driver of claim 20 in which said digital representation includes a bitmap having a resolution twice that of the resolution of the raster print engine.

Claim 28

Dependent Claim 28 words

The print engine driver of claim 25 in which the transitions in a cell print area are generated from parts of three adjacent horizontal lines of said bitmap.

Claim 29

Dependent Claim 40 words

The print engine driver of claim 26 in which said means for generating includes means for weighting bits of the parts of the three horizontal lines of said bitmap from which the transitions in the cell print area are generated.

Claim 30

Dependent Claim 44 words

The print engine driver of claim 27 in which bits of the central bitmap line are weighted more than bits of an outer bitmap lines of the three horizontal lines of said bitmap from which the transitions in a cell print area are generated.

Claim 31

Dependent Claim 19 words

The print engine driver of claim 22 in which the incoming data includes data representative of image outline edges.

Claim 32

Dependent Claim 29 words

The print engine driver of claim 29 in which said means for generating includes means for determining when an image outline edge passes non-vertically through a cell print area.

Claim 33

Dependent Claim 32 words

The print engine driver of claim 30 in which said means for generating generates at least two drive signal transitions to represent a non-vertical outline edge passing through a cell print area.

Claim 34

Dependent Claim 113 words

A raster print engine driver for reproducing a text or line art image from incoming data representative of the image, in which the reproduced image has an apparent vertical resolution greater than that of the print engine, comprising: means for establishing a cell scan time period representing an elemental cell print area of at least 0.005" in length; and means for driving an print engine to reproduce in a cell print area the amount of image darkness in the cell print area with an accuracy of at least five bits and the horizontal center of gravity of the image darkness in the cell print area with an accuracy of at least three bits.

Claim 35

Dependent Claim 113 words

A raster print engine driver for reproducing a text or line art image from incoming data representative of the image, in which the reproduced image has an apparent vertical resolution greater than that of the print engine, comprising: means for establishing a cell scan time period representing an elemental cell print area of at least 0.005" in length; and means for driving an print engine to reproduce in a cell print area the amount of image darkness in the cell print area with an accuracy of at least five bits and the horizontal center of gravity of the image darkness in the cell print area with an accuracy of at least three bits.

Claim 36

Dependent Claim 120 words

A raster print engine driver for generating, from incoming data pixels representative of a continuous tone image, a transition-modulated engine drive signal for causing a print engine to reproduce the image as a series of modulated print lines forming position-modulated halftone dots, comprising: means for establishing a halftone dot print area including a pair of input data pixels on each of two different input data lines; and means said two pairs of generating, from four input data pixels in said halftone dot print area, a plurality of independently located drive signal transitions to cause the print engine to change state at selected points in said halftone dot print area to produce a halftone dot from said four input data pixels.

Claim 37

Dependent Claim 120 words

A raster print engine driver for generating, from incoming data pixels representative of a continuous tone image, a transition-modulated engine drive signal for causing a print engine to reproduce the image as a series of modulated print lines forming position-modulated halftone dots, comprising: means for establishing a halftone dot print area including a pair of input data pixels on each of two different input data lines; and means said two pairs of generating, from four input data pixels in said halftone dot print area, a plurality of independently located drive signal transitions to cause the print engine to change state at selected points in said halftone dot print area to produce a halftone dot from said four input data pixels.

Claim 38

Dependent Claim 36 words

The print engine driver of claim 33 in which said means for generating produces a halftone dot centered in said print area when the value of each of the four input data pixels is the same.

Claim 39

Dependent Claim 46 words

The print engine driver of claim 33 in which said means for generating produces a halftone dot displaced vertically or horizontally from the center of said print area when a center of gravity of the four input data pixels is not centered in said print area.

Claim 40

Dependent Claim 58 words

The print engine driver of claim 33 in which said means for generating produces a halftone dot distorted diagonally within said print area when the center of gravity of the pair of input data pixels from the top input data line is different than that of the pair of input data pixels from the bottom input data line.

Claim 41

Dependent Claim 34 words

The print engine driver of claim 33 in which said means for generating includes means for creating a computed pair of data pixels for each engine scan line through said halftone dot print area.

Claim 42

Dependent Claim 61 words

The print engine driver of claim 37 in which said computed pair of data pixels is based on a weighted average of values of both pairs of input data pixels for a halftone dot print area, in which the weighting for the weighted average is determined by the vertical position within the halftone dot print area of the engine scan line.

Claim 43

Dependent Claim 57 words

The print engine driver of claim 38 in which said weighting is one hundred percent of the upper pair of input pixels for scan lines above the center of the halftone dot print area and one hundred percent of the lower pair of input pixels for scan lines below the center of the halftone dot print area.

Claim 44

Dependent Claim 34 words

The print engine driver of claim 33 in which said means for generating includes means for altering a value of at least one of said four input data pixels to sharpen said reproduced image.

Claim 45

Dependent Claim 31 words

The print engine driver of claim 40 in which said means for altering includes means for exaggerating differences in value among the four input data pixels in at least one dimension.

Claim 46

Dependent Claim 36 words

The print engine driver of claim 33 in which said print engine driver generates one of at least the cases of zero and two independently located drive signal transitions from each pair of input data pixels.

Claim 47

Dependent Claim 26 words

The print engine driver of claim 37 in which said means for generating includes a lookup table for storing data representative of the drive signal transitions.

Claim 48

Dependent Claim 34 words

The print engine driver of claim 43 in which said lookup table is addressed with at least one of the sum and the difference of the values of the computed pair of data pixels.

Claim 49

Dependent Claim 39 words

The print engine driver of claim 37 in which said means for generating includes means for averaging each pair of computed data pixels to determine the density of the portion of the halftone dot on that engine scan line.

Claim 50

Dependent Claim 38 words

The print engine driver of claim 45 in which said means for generating further includes means for horizontally displacing said portion of the halftone dot to reproduce the center of gravity of the computed pair of data pixels.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1995-04-28	1995-10-28	1996-04-28	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1999-04-28	1999-10-28	2000-04-28	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2003-04-28	2003-10-28	2004-04-28	$7700.00	Window Closed / Lapsed

Raster scanning engine driver which independently locates engine drive signal transistors within each cell area

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