Thermal ribbon encoder assembly for a thermal printing postage meter

• Main Authors: SCHULTE; ROBERT B, PORTER; LORRAINE T, TAYLOR; BRUCE E
• Format: Patent
• Language: English
• Published: 11.10.1994
• Edition: 5
• Subjects: CHECKING-DEVICES; CORRECTION OF TYPOGRAPHICAL ERRORS; FARE-REGISTERING APPARATUS; FRANKING APPARATUS; i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; LINING MACHINES; PERFORMING OPERATIONS; PHYSICS; PRINTING; SELECTIVE PRINTING MECHANISMS; STAMPS; TICKET-ISSUING APPARATUS; TRANSPORTING; TYPEWRITERS

The thermal printing apparatus includes a base supported registration wall. The registration wall has claps mounted thereto for supporting a thermal ribbon cassette. Also, mounted to the registration wall is a thermal print head which extends over the deck of the thermal print apparatus to define a print station. A platen roller support assembly is mounted in the base for supporting the platen roller parallel to the thermal print head and causing the platen roller to bias an envelope against the thermal print head and causing the envelope and thermal transfer ribbon to simultaneously traverse the thermal print head during a print cycle of the thermal printing apparatus under the influence of a drive motor. An encoder is mounted to the registration wall to interact with the thermal transfer ribbon for position encoding displacement of the thermal ribbon of the thermal ribbon cassette relative to the thermal print head. The output of the encoder is proportional to the rate of change of the position encoded displacement. A microcontroller system is provided for causing the drive motor to drive the platen roller as a select speed and for comparing the output of the encoder means to a desired print speed. If a difference is detected, the microcontroller incrementally increases the drive motor speed until the difference is within a desired minimum range.