| 摘要 |
2136093 9324302 PCTABS00028 Apparatus for controlling heating of heat sealing dies (12) relative to a target temperature has one or more electrical resistance heating elements (10) switched between "on" and "off" states for getting electrical power, according to frequency and durations of control signals. A first signal (from 42) proportional to said target temperature and a second signal (from 18) proportional to actual temperature to be controlled are compared (36, 38) to gauge prevailing temperature difference. Means (28, 30; 24, 26) responsive to comparison results is operative for varying said durations and said frequency of the control signals, both according to said temperature difference and to reduce same. |
