Method and system to calculate line feed error in labels on a printer
A system to calculate line feed error in labels on a printer includes a holder assembly under the label line feed and before the printer burn line; a first sensor and a second sensor on the holder assembly, a fixed distance, L, between them; and a processor. The first sensor senses a first position of a label edge, L 1 A. The second sensor senses a second position of the label edge, L 1 B. The processor calculates the distance, L 1 AB, between the first position and the second position and calculates the line feed error over the fixed distance, L, by taking the difference (L−L 1 AB). The processor calculates the feed correction to be done to the label, given by [(L−L 1 AB)/L]×D, where D is a distance between the first sensor and the burn line of the printer. The processor instructs the printer line feed to implement the calculated feed correction.
1. A method of calculating line feed error on a printer comprising the steps of:
a) providing a first sensor and a second sensor under a feed line, wherein the first sensor and the second sensor are separated by a fixed distance;
b) sensing a first position of a first optical feature of a label by the first sensor as the label moves near the first sensor;
c) sensing a second position of the first optical feature of the label by the second sensor as the label moves near the second sensor;
d) calculating a deviation between the fixed distance and distance between the first position and the second position calculation;
e) calculating a ratio of the calculated deviation with respect to the fixed distance; and
f) calculating a feed correction by applying the ratio to a distance value, wherein the distance value is a distance between the first sensor and a burn line of the printer.
2. The method of claim 1 , comprising the step of g) correcting the line feed based upon the step f) of calculating the feed correction.
3. The method of claim 2 , wherein the calculating steps d-f and the correcting step are accomplished with a processor.
4. The method of claim 1 , wherein the fixed distance has a tolerance of about +/−20 microns.
5. The method of claim 1 , wherein the first optical feature is defined as a change in the opacity between label and edge.
6. The method of claim 1 , wherein the first optical feature is a fluorescent stripe, the fluorescent stripe being disposed at a predetermined position on the label and at the same predetermined position on every label fed near the first and second sensors.
7. The method of claim 1 , wherein the deviation is defined as the difference between the fixed distance and the distance between the first position and the second position calculation.
8. A method of calculating line feed error on a printer comprising:
sensing, with a first sensor, a first position of an optical feature of a label as the label moves in a feed line;
sensing, with a second sensor, a second position of the optical feature of the label as the label moves in the feed line, wherein the first sensor and the second sensor are separated by a fixed distance;
calculating a distance between the first position and the second position; and
calculating a line feed error by subtracting the calculated distance from the fixed distance.
9. The method of claim 8 , comprising calculating a feed correction by dividing the calculated line feed error by the fixed distance and multiplying the quotient by a distance between the first sensor and a printer burn line.
10. The method of claim 9 , comprising correcting the line feed based on the calculated feed correction.
11. The method of claim 8 , wherein the optical feature is at least one of a differential transmissivity or a differential in reflectance between an edge of the label and a carrier media.
12. The method of claim 8 , wherein the fixed distance has a tolerance of about +/−20 microns.
13. The method of claim 8 , wherein the optical feature of the label is selected from the leading edge and the trailing edge of the label.
14. The method of claim 13 , wherein the optical feature is a fluorescent stripe.
15. A system to calculate line feed error on a printer, comprising:
a first sensor and a second sensor separated by a fixed distance;
the first sensor being configured to sense a first position of a first optical feature of a label as the label moves near the first sensor;
the second sensor being configured to sense a second position of the first optical feature of the label as the label moves near the second sensor; and
a processor communicatively linked to the first sensor and the second sensor, the processor being configured to:
calculate a deviation between the fixed distance and distance between the first position and the second position calculation;
calculate a ratio of the calculated deviation with respect to the fixed distance; and
calculate a feed correction by applying the ratio to a distance value, wherein the distance value is a distance between the first sensor and a burn line of the printer.
16. The system of claim 15 , wherein the processor is further configured to correct the line feed based upon the calculated feed correction.
17. The system of claim 15 , wherein the first optical feature is at least one of a differential transmissivity or a differential in reflectance between an edge of the label and a carrier media.
18. The system of claim 15 , wherein the fixed distance has a tolerance of about +/−20 microns.
19. The system of claim 15 , wherein the first optical feature of the label is defined as a change in the opacity between label and edge.
20. The system of claim 15 , the first optical feature is a fluorescent stripe, the fluorescent stripe being disposed at a predetermined position on the label and at the same predetermined position on every label fed near the first and second sensors.