Method of and apparatus for preventing overheating of heating element

• Main Authors: ITOH, TOSHIKAZU OKI ELECTRIC INDUSTRY CO., LTD, SUEMUNE, TOSHIROH OKI ELECTRIC INDUSTRY CO., LTD
• Format: Patent
• Language: English; French; German
• Published: 07.01.1988
• Edition: 4
• Subjects: CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORSOR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; CORRECTION OF TYPOGRAPHICAL ERRORS; ELECTRICITY; EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS; GENERATION; i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; LINING MACHINES; PERFORMING OPERATIONS; PHYSICS; PRINTING; REGULATING; SELECTIVE PRINTING MECHANISMS; STAMPS; SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES; TRANSPORTING; TYPEWRITERS

An element which in use emits heat, e.g. a line feed motor (LF) for a printer, is prevented from overheating. Normally, the printer increments the LF motor line by line at a rate which does not overheat the LF motor. However, if the motor is driven substantially continuously, overheating may occur. To prevent this, a first timer TM1 is set to count a first time interval t1. The number of line feed increments is counted during t1 to provide a first heat release signal P indicative of the heat generated by the motor. If P exceeds a prescribed value (i.e. if overheating occurs) a timer TM2 is started. During the time that TM2 is operative, the LF motor can only be incremented at a slower rate that would be correspondingly possible during the period t1, for causing cooling of the motor. A second heat release signal P is determined for the period t2 of the time TM2. If the second heat release signal is less than a prescribed value the motor returns to normal operation under the control of timer TM1; otherwise it is controlled for a further period under timer TM2 to promote cooling.