Touch key and induction heating cooking device employing the same
View Patent ↗A touch key detects that an object touches the touch key. The touch key includes an electrode arranged to be touched with the object, an oscillator for outputting a high-frequency voltage and applies the high-frequency voltage to the electrode, a rectifier for rectifying and smoothing the high-frequency voltage output from the oscillator as to output a direct-current (DC) voltage, a reference voltage generator for generating a reference voltage, a subtracter for subtracting the reference voltage from the DC voltage output from the rectifier, a judging unit for detecting a voltage difference between the voltage output from the subtracter before and after changing and for determining that the object touches the electrode when the voltage difference exceeds a predetermined value. This touch key detects that an object touches the electrode with high sensitivity, and enhances the reliability of the judging unit.
1. A cooker comprising:
a touch key including:
an electrode arranged to be touched with an object;
an oscillator for outputting a high-frequency voltage and supplying the high-frequency voltage to the electrode;
a rectifier for rectifying and smoothing the high-frequency voltage supplied from the oscillator as to output a direct-current (DC) voltage;
a differentiator for differentiating the voltage output from the rectifier; and
a judging unit for determining that the object touches the electrode when the voltage output from the differentiator falls;
a top plate having the touch key provided thereon; and
an induction heater for induction-heating an object to be heated placed on the top plate according to a judgment result of the judging unit of the touch key.
2. A cooker according to claim 1 , wherein the judging unit determines that the object touches the electrode when the voltage output from the differentiator falls and when a change of the voltage output from the differentiator is larger than a predetermined value.
3. A cooker according to claim 1 , wherein the judging unit determines that the object moves apart from the electrode when the voltage output from the differentiator rises.
4. A cooker according to claim 3 , wherein the judging unit determines that the object moves apart from the electrode when the voltage output from the differentiator rises and when a change of the voltage output from the differentiator is larger than a predetermined value.