Temperature controller
First Claim
1. A device for controlling a temperature of an electrical appliance , comprising:
- a heating device for heating said electrical appliance;
a thyristor connected to an AC voltage source in series with the heating device;
a temperature setting circuit for predetermining a target temperature level at which the temperature of the electrical appliance is to be maintained and outputting a signal indicative of the target temperature level;
a temperature detecting circuit for detecting the temperature of the electrical appliance and outputting a signal indicative thereof;
a first pulse generator coupled to said AC voltage source for outputting a first pulse signal during the time period in which the phase of the output voltage of said AC voltage source is negative, wherein the trailing edge of said first pulse signal is prior to the zero point of the output voltage of said AC voltage source;
a comparator for outputting a signal indicative of a high temperature condition of said heating device by comparing the signal indicative of the target temperature level from said temperature setting circuit and the signal indicative of the temperature of the electrical appliance ; and
a trigger circuit for outputting a trigger pulse to said thyristor when both said first pulse signal and said high temperature indicative signal overlap, the pulse width of the trigger pulse extending beyond the zero point of said output voltage;
1 Assignment
0 Petitions
Accused Products
Abstract
A temperature controller compares a temperature detection signal outputted from a temperature sensor with a set temperature preliminary set in a temperature setting circuit. According to a result of the comparison and before a zero-cross point of an AC voltage applied from a commercial AC source to a heating member, a driving circuit of the temperature controller outputs a driving signal to a thyristor to turn ON the thyristor at the zero-cross point. Then the AC voltage is applied to the heating member via the thyristor. Since the determination of turning ON or OFF the thyristor is made before the zero-cross point of the AC voltage applied through the thyristor, the thyristor may surely be turned ON or OFF at the zero-cross point to prevent electromagnetic wave noises from occurring.
22 Citations
13 Claims
-
1. A device for controlling a temperature of an electrical appliance , comprising:
-
a heating device for heating said electrical appliance; a thyristor connected to an AC voltage source in series with the heating device; a temperature setting circuit for predetermining a target temperature level at which the temperature of the electrical appliance is to be maintained and outputting a signal indicative of the target temperature level; a temperature detecting circuit for detecting the temperature of the electrical appliance and outputting a signal indicative thereof; a first pulse generator coupled to said AC voltage source for outputting a first pulse signal during the time period in which the phase of the output voltage of said AC voltage source is negative, wherein the trailing edge of said first pulse signal is prior to the zero point of the output voltage of said AC voltage source; a comparator for outputting a signal indicative of a high temperature condition of said heating device by comparing the signal indicative of the target temperature level from said temperature setting circuit and the signal indicative of the temperature of the electrical appliance ; and a trigger circuit for outputting a trigger pulse to said thyristor when both said first pulse signal and said high temperature indicative signal overlap, the pulse width of the trigger pulse extending beyond the zero point of said output voltage; - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
-
Specification