Patent ID: 7608805
Filing Date: 2009-10-27
Classification: B23K,G05D

Abstract:
1. A battery powered heating device comprising: a battery; a heating tip including a coil resistance heating element; a first electrical line for delivering a voltage “Vb” from the battery to the heating tip, the first electrical line including a first switch, the heating tip receiving Vb when the first switch is closed; a constant voltage circuit operatively coupled to the battery; a second electrical line for delivering a voltage “V” from the constant voltage circuit to the heating tip, the second electrical line including a second switch, the heating tip receiving V when the second switch is closed; a controller adapted to perform a plurality of subroutines that selectively open and close the first switch and selectively open and close the second switch, the controller further adapted to determine a present sensed voltage value “Vn” when the heating tip receives V, Vn dependent on resistance of the heating tip and representative of a temperature of the heating tip, the controller further adapted to compare a prior sensed voltage value “Vp” with Vn, and to select one of the plurality of subroutines in accordance with the comparison of Vp with Vn, wherein during at least one of the subroutines the controller calculates a time interval based on Vb and allows the heating tip to receive Vb during the calculated time interval, wherein V is less than Vb, and wherein V and Vb are greater than zero.