Thermal printer head with print control devices

A thermal printer for printing on a voucher, comprising

• (a) a printer mechanism including an upper portion for generating print electronic information;
• (b) a thermal printer head connected with one side of said printer mechanism upper portion for printing an image on one surface of the voucher in accordance with said print electronic information;
• (c) an alignment roller arranged spaced from and opposite said thermal printer head, the voucher passing between said alignment roller and said thermal printer head;
• (d) an image sensor arranged on said one side of said printer mechanism upper portion adjacent to and downstream from said thermal printer head for reading the image printed on the voucher surface by said thermal printer head and transforming said read image into actual electronic information corresponding with the read image;
• (e) a spring connected with said printer mechanism on a side opposite said one side for biasing said printer mechanism in the direction of said alignment roller and said thermal printer head into contact with the voucher and said image sensor adjacent the voucher;
• and
• (f) a print control unit connected with said printer mechanism and with said image sensor for comparing said print electronic information with said actual electronic information, said print control unit stopping printing when said actual electronic information differs from said print electronic information.