Print precision improvement over long print jobs

1. A method of printer compensation, comprising:

using a sensor, detecting a time T(1) associated with a first label position;

using the sensor, detecting a time T(L) associated with a second label position that is L labels later in a print job;

from at least the times T(1) and T(L) and a media feed rate, calculating a difference between the first label position and the second label position; and

compensating an adjustment factor by the difference between the first label position and the second label position to account for changes in print position along a label travel path.

2. The method according to claim 1 , where the calculating comprises converting times T(1) and T(L) to a distance.

3. The method according to claim 1 , where the calculating comprises converting times T(1) and T(L) to a distance represented in printed dots in a feed direction.

4. The method according to claim 1 , where detecting the value T(1) further comprises detecting a sequence of M values T(1) through T(M); and

where detecting the value of T(L) further comprises detecting a sequence of M adjacent values about label L.

5. The method according to claim 4 , further comprising averaging the values of T(1) through T(M) to produce TA(1); and

averaging the values of the M adjacent values about label L to produce TA(L).

6. The method according to claim 5 , where the calculating comprises from at least the times TA(1) and TA(L), and a feed rate, calculating a difference between the first label position and the second label position.

7. The method according to claim 4 , further comprising:

converting the M values T(1) through T(M) to distances D(1) through D(M); and

converting the M adjacent values about label L to M distances D(L−M) through D(L).

8. The method according to claim 4 , further comprising averaging the values of D(1) through D(L) to produce DA(1); and

averaging the values of the M adjacent values about label L to produce DA(L).

9. The method according to claim 5 , where the calculating comprises using the distances DA(1) and DA(L) to calculate a difference between the first label position and the second label position.

10. A method of printer compensation, comprising:

using a sensor detecting a sequence of time values T(1) through T(M) associated with a first label position;

converting the M values T(1) through T(M) to distances D(1) through D(M);

using the sensor, detecting times T(L−M) through T(L) associated with a M label positions that are approximately L labels later in the print job;

converting the M adjacent values about second label L to L distances D(L−M) through D(L);

averaging the values of D(1) through D(M) to produce DA(1);

averaging the values of D(L−M) through D(L) to produce DA(L);

from at least the distances DA(1) and DA(L), calculating a difference between the first label position and the second label position; and

compensating an adjustment factor by the difference between the first label position and the second label position to account for changes in print position along a label travel path.

11. The method according to claim 10 , where the distances are represented in printed dots in a feed direction.

12. A label printer device, comprising:

a sensor that detects a transition between labels;

a processor that receives and interprets signals from the sensor;

a motor that advances a label medium through the printer;

the processor being programmed to:

use the sensor to detect a time T(1) associated with a first label position;

use the sensor to detect a time T(L) associated with a second label position that is L labels later in the print job;

from at least the times T(1) and T(L), and a printer feed rate, calculate a difference between the first label position and the second label position; and

compensate an adjustment factor by the difference between the first label position and the second label position to account for changes in print position along a label travel path.

13. A label printer device according to claim 12 where the transition comprises at least one of a space, black mark, hole, or optical element.

14. The apparatus according to claim 12 , where the processor is programmed to convert times T(1) and T(L) to distances.

15. The apparatus according to claim 12 , where the processor:

in detecting the value T(1) is further programmed to detect a sequence of M values T(1) through T(M); and

in detecting the value of T(L) is further programmed to detect a sequence of M adjacent values about label L.

16. The apparatus according to claim 15 , where the processor is further programmed to:

average the values of T(1) through T(M) to produce TA(1);

average the values of the M adjacent values about label L to produce TA(L); and

calculate from at least the times TA(1) and TA(L), and a printer media feed rate a difference between the first label position and the second label position.

17. The apparatus according to claim 15 , where the processor is programmed to:

convert the M values T(1) through T(M) to distances D(1) through D(M);

convert the M adjacent values about label L to M distances D(L−M) through D(L);

average the values of D(1) through D(M) to produce DA(1); and

average the values of the M adjacent values about label L to produce DA(L).

18. The apparatus according to claim 12 , where the processor is programmed to calculate a difference between the distances DA(1) and DA(L) to calculate a difference between the first label position and the second label position.

19. The apparatus according to claim 18 , where the distances DA(1) and DA(L) are represented as a number of printed dots in a feed direction.

20. The apparatus according to claim 12 , where the processor is programmed to carry out the compensating by adjusting a value of an adjustment factor.