US 5,349,375 A · Ink jet printer dot placement compensation method

Abstract

In a printer having P+X printing elements for printing pixels with a vertical center-to-center spacing R.sub.1 during a plurality of line scans, and a stepper motor for moving a record medium in increments R.sub.2 where R.sub.2 is greater than R.sub.1, all points addressable printing is obtained by a combination of movement of the record medium orthogonal to the line scan direction and shifting address signals applied to the print elements. The stepper motor moves the record medium a distance k.sub.2 R.sub.2 between successive line scans and address signals are applied to (n+k.sub.1)th . . . (n+k.sub.1 +P-1)th print elements to cause a shift k.sub.1 R.sub.1 such that the sum of the distance the record medium is moved before a line scan and the shift caused by the address signals during a scan is equal to PR.sub.1 where P is the number of print elements active during the preceding line scan, or equal to any desired integral multiple of R.sub.1 in other print modes. With a print head capable of printing pixels on 1/300 inch centers, and a stepper motor capable of moving the record medium in minimum increments of 1/150 inch, all points addressable printing with a pixel resolution of 1/300 inch is achieved with increased accuracy. This same arrangement also permits printing in the character mode with a line-to-line spacing of exactly 1/6 inch. In a second embodiment the line-to-line spacing differs from 1/2 inch by a distance that has minimal impact on print quality.

Claims18

Dependent claims

A method of operating a printer mechanism having a print head for printing pixels on a record medium during a plurality of line scans as said print head is moved along an axis relative to said record medium, and a stepper motor for moving said record medium in a direction orthogonal to said axis, said print head having print elements 1,2, . . . P,(P+1) . . . (P+X) responsive to selectively applied address signals 1, 2, . . . P for selectively printing pixels at adjacent pixel positions aligned in the direction of record medium movement with a distance R.sub.1 between centers of adjacent pixel positions, and said stepper motor being responsive to energizing pulses for moving said record medium by a minimum distance R.sub.2 where R.sub.2 is greater than R.sub.1, said method comprising the steps of:

during a given one of said line scans, applying the address signals 1, 2, . . . P to said print elements (n), (n+1), . . . (n+P-1) whereby no more than P of said print elements print pixels during said given one of said line scans, n being a positive integer from 1 to X;
after said given one of said line scans, applying pulses to the stepper motor to move the record medium a distance k.sub.2 R.sub.2 ;
and,
during another of the line scans following said movement of the record medium by said distance k.sub.2 R.sub.2, applying the address signals 1, 2, . . . P to said print elements (1+k.sub.1),(2+k.sub.1) . . . (P+k.sub.1) whereby pixels are printed with a shift of k.sub.1 R.sub.1 in a direction parallel to the direction the record medium is moved,
where k.sub.2, P and X are positive integers and k.sub.1 is an integer no less than 0 and k.sub.1 R.sub.1 +k.sub.2 R.sub.2 =PR.sub.1.

2 more elements

A method of operating a printer mechanism to obtain all points addressable printing of pixels over plural line scans with the center-to center distance between all pixel print positions in the director of record movement being exactly R.sub.1, said printer mechanism having a print head for printing pixels on a record medium during a plurality of line scans as said print head is moved along an axis relative to said record medium, and a stepper motor for moving said record medium in a direction orthogonal to said axis, said print head having print elements 1,2, . . . P,(P+1) . . . (P+X) responsive to selectively applied address signals 1, 2, . . . P for selectively printing pixels at adjacent pixel positions aligned in the direction of record medium movement with a distance R.sub.1 between centers of adjacent pixel positions, and said stepper motor being responsive to energizing pulses for moving said record medium by a minimum distance R.sub.2 where R.sub.2 is greater than R.sub.1, said method comprising the following steps:

step 1) during each of said line scans, applying the address signals 1, 2, . . . P to said print elements (1+k.sub.1),(2+k.sub.1), . . . (P+k.sub.1) whereby pixels are printed with a shift distance of k.sub.1 R.sub.1 relative to where pixels would have been printed if said signals had been applied to said print elements 1, 2, . . . P, respectively, the shift distance being in a direction parallel to the direction the record medium is moved, k.sub.1 being an integer from 0 to X;
step 2) between successive ones of said line scans, applying a number of pulses to the stepper motor to move the record medium a distance k.sub.2 R.sub.2, and,
step 3) repeatedly carrying out step 1 and step 2 while applying said address signals to different ones of said print elements to vary said shift distance k.sub.1 R.sub.1, and while varying the number of pulses applied to said stepper motor so that a sum of the distance k.sub.2 R.sub.2 that the record medium is moved when a given step 2 is carried out and the shift distance k.sub.1 R.sub.1 that the pixels are printed during a step 1 next succeeding said given step 2 is equal to PR.sub.1, k.sub.2, P and X being positive integers.

A method of operating a printer mechanism having a print head for printing pixels on a record medium during a plurality of line scans as said print head is moved along an axis relative to said record medium, and a stepper motor for moving said record medium in a direction orthogonal to said axis, said print head having a plurality of print elements 1,2 . . . P,(P+1) . . . (P+X) responsive to selectively applied address signals 1, 2, . . . P for selectively printing pixels at adjacent pixel positions aligned in the direction of record medium movement with a distance R.sub.1 between centers of adjacent pixel positions, and said stepper motor being responsive to energizing pulses for moving said record medium by a minimum distance R.sub.2 where R.sub.2 is greater than R.sub.1, said method comprising the following steps:

step 1) during a given one of said line scans, applying the address signals 1, 2, . . . P to said print elements (1+k.sub.1), (2+k.sub.1) . . . (P+k.sub.1) whereby said print elements print pixels which are shifted by a shift distance k.sub.1 R.sub.1 relative to where pixels would have been printed if said addressing signals had been applied to said print elements 1,2, . . . P, respectively, the shift distance being parallel to the direction the record medium is moved and k.sub.1 being zero or a positive integer no greater than X;
step 2) between successive ones of said line scans, applying pulses to the stepper motor to move the record medium a distance k.sub.2 R.sub.2 ;
and,
step 3) repeatedly executing step 1 and step 2 while applying said address signals to different ones of said print elements to vary said shift distance k.sub.1 R.sub.1 and while varying the number of pulses applied to said stepper motor so that a sum of the distance k.sub.2 R.sub.2 that the record medium is moved when step 2 is executed and the shift distance k.sub.1 R.sub.1 that the pixels are printed during a next succeeding execution of step 1 differs from PR.sub.1 by no more than one-half R.sub.1, k.sub.2, P and X being positive integers.

1 more element

Dependencies are inferred from the claim text.

Ink jet printer dot placement compensation method

Life of this patent

Ink jet printer dot placement compensation method

Life of this patent

Abstract

Claims18