Single motor dynamic ribbon feedback system for a printer

A printer comprising:

• a rotatable ribbon supply spindle;
• an encoder sensor for determining the diameter of a ribbon loaded on the ribbon supply spindle;
• a sensor for determining width of the ribbon loaded on the ribbon supply spindle;
• a rotatable ribbon take-up spindle for taking up the ribbon;
• an encoder sensor on the ribbon take-up spindle for determining the diameter of the ribbon on the take-up spindle;
• a drive system configured to rotate the ribbon take-up spindle, the drive system being powered by an electric power supply, the drive system further providing rotation to the rotatable ribbon supply spindle via tension on a ribbon loaded on the rotatable ribbon supply spindle and taken-upon the rotatable take-up ribbon spindle;
• firmware, the firmware being communicatively linked to receive sensor outputs from the encoder sensor on the ribbon supply spindle, the sensor for determining ribbon width, and the encoder sensor on the ribbon take-up spindle;
• the firmware being configured to determine torque in the ribbon at the supply spindle based upon the output from the sensor for determining width of the ribbon on the ribbon supply spindle;
• the firmware being configured to calculate the total tension in the ribbon supply based upon the torque determined at in the ribbon at the supply spindle and based upon the output from the encoder sensor on the ribbon supply spindle, the firmware calculation being SRT/SRR, where SRT is Supply Ribbon Torque and SRR is Supply Ribbon Radius;
• the firmware being further configured to calculate the torque in the rotatable ribbon take-up spindle required to match the ribbon tension in the take-up spindle to the ribbon tension in the supply spindle based upon the calculated total tension in the ribbon supply and the output from the encoder sensor on the ribbon take-up spindle, the firmware calculation being (SRT/SRR)*TRR, where TRR is the radius of the ribbon at the take-up spindle;
• the firmware being communicatively linked to the electric power supply and configured to control current supplied to the drive system, the current being proportional to a rate of rotation of the drive system and the take-up spindle;
• and
• the firmware being configured to adjust the current supplied to the drive system so that the torque at the take-up spindle is the calculated torque required to match the ribbon tension in the take-up spindle to the ribbon tension in the supply spindle.

A method of controlling ribbon tension on a printer, the printer having a rotatable ribbon supply spindle, a rotatable ribbon take-up spindle, and a motor driving the ribbon take-up spindle, comprising the steps of:

• i. sensing the diameter of the ribbon on the ribbon supply spindle;
• ii. sensing the ribbon width on the ribbon supply spindle;
• iii. calculating tension on the ribbon at the ribbon supply spindle, the tension based upon the first and second sensing steps;
• iv. sensing the ribbon diameter of the ribbon at ribbon take-up spindle;
• v. calculating the torque required to match tensions between the ribbon supply and the ribbon take-up based upon the first calculating step and the third sensing step;
• and
• vi. adjusting the motor driving the ribbon take-up spindle to supply the required torque found in the second calculating step.

The method of 17, wherein the first calculating step is accomplished with firmware, wherein the first calculating step is comprised of the steps of:

• receiving information about the diameter of the ribbon on the ribbon supply spindle from the first sensing step;
• receiving information about the width of the ribbon on the ribbon supply spindle from the second sensing step;
• converting the information about the width of the ribbon into a torque;
• and
• dividing the torque by the ribbon radius derived from the information about diameter or the ribbon to obtain a supply ribbon tension.