Non-linear power control of a thermal print head in a plastic card printer
Printing multi-color images on non-vinyl plastic identification documents in identification document printing systems. A non-linear pixel density adjustment curve is used to adjust the pixel density data of a multi-color image to be printed which adjusts the power applied to the thermal print head. The use of a non-linear pixel density adjustment curve to adjust the pixel density data improves the quality of the resulting multi-color printed image, reduces mass transfer of the dye donor layer, and reduces breaking of the carrier film of the print ribbon.
1. A method of printing a multi-color image on an identification document made of polyethylene terephthalate glycol or polycarbonate in a print station of an identification document printing system, comprising:
inputting print data corresponding to the multi-color image to be printed into a printer controller that controls operation of a thermal print head of the print station that includes a multicolor print ribbon, the print data including pixel density data;
processing the print data to adjust the pixel density data using a non-linear pixel density adjustment curve to create modified pixel density data; and
using the modified pixel density data to control the thermal print head of the print station to print the multi-color image on the polyethylene terephthalate glycol or polycarbonate identification document using the multicolor print ribbon.
2. The method of claim 1 , comprising printing the multi-color image directly onto the polyethylene terephthalate glycol or polycarbonate identification document.
3. The method of claim 1 , wherein the non-linear pixel density adjustment curve comprises a parametric curve.
4. The method of claim 3 , wherein the parametric curve comprises a quadratic curve.
5. The method of claim 1 , wherein the polyethylene terephthalate glycol or polycarbonate identification document comprises a polyethylene terephthalate glycol or polycarbonate card, and the multi-color image comprises a portrait image of a person.
6. The method of claim 1 , further comprising:
prior to or after printing the multi-color image, at least one of the following:
encoding data on a magnetic stripe on the polyethylene terephthalate glycol or polycarbonate identification document;
programming data on an integrated circuit chip on the polyethylene terephthalate glycol or polycarbonate identification document;
printing data on the polyethylene terephthalate glycol or polycarbonate identification document;
using a laser to mark data on the polyethylene terephthalate glycol or polycarbonate identification document.
7. A method of printing a multi-color portrait image of a person on a polyethylene terephthalate glycol plastic card in a print station of plastic card printing system, comprising:
inputting print data corresponding to the multi-color portrait image to be printed into a printer controller that controls operation of a thermal print head of the print station that includes a multicolor print ribbon, the print data including pixel density data;
processing the print data to adjust the pixel density data using a non-linear pixel density adjustment curve to create modified pixel density data; and
using the modified pixel density data to control the thermal print head of the print station to print the multi-color portrait image onto the polyethylene terephthalate glycol plastic card using the multicolor print ribbon.
8. The method of claim 7 , wherein the non-linear pixel density adjustment curve comprises a parametric curve.
9. The method of claim 8 , wherein the parametric curve comprises a quadratic curve.
10. The method of claim 7 , further comprising:
prior to or after printing the multi-color portrait image, at least one of the following:
encoding data on a magnetic stripe on the polyethylene terephthalate glycol plastic card;
programming data on an integrated circuit chip on the polyethylene terephthalate glycol plastic card;
printing data on the polyethylene terephthalate glycol plastic card;
using a laser to mark data on the polyethylene terephthalate glycol plastic card.
11. A plastic card printing system, comprising:
a card input configured to input a polyethylene terephthalate glycol or polycarbonate plastic card;
a print station having at least one print ribbon and at least one thermal print head;
a card transport mechanism for transporting the polyethylene terephthalate glycol or polycarbonate plastic card from the card input to the print station;
a printer controller connected to and controlling operation of the thermal print head, the printer controller is programmed to include a non-linear pixel density adjustment curve to adjust pixel density data of a multi-color image to be printed.
12. The plastic card printing system of claim 11 , wherein the non-linear pixel density adjustment curve comprises a parametric curve.
13. The plastic card printing system of claim 12 , wherein the parametric curve comprises a quadratic curve.
14. The plastic card printing system of claim 11 , further comprising at least one of the following:
an encoder that is configured to encode data on a magnetic stripe on the polyethylene terephthalate glycol or polycarbonate plastic card;
a chip programmer that is configured to program data on an integrated circuit chip on the polyethylene terephthalate glycol or polycarbonate plastic card;
an additional printer that is configured to print data on the polyethylene terephthalate glycol or polycarbonate plastic card;
a laser that is configured to mark data on the polyethylene terephthalate glycol or polycarbonate plastic card.