초록 ▼

A system for controlling the temperature at a location which is heated by a heater. The heater is intermittently energized by a source of electrical power in response to control signals from a temperature control circuit. The temperature control circuit includes a comparator-amplifier having one inp

A system for controlling the temperature at a location which is heated by a heater. The heater is intermittently energized by a source of electrical power in response to control signals from a temperature control circuit. The temperature control circuit includes a comparator-amplifier having one input coupled to a sensed temperature signal. The other input to the comparator-amplifier is a set point temperature level. The sensed temperature signal is produced by a bridge circuit including a temperature sensor at the location which is being heated. The comparator-amplifier includes a feedback network to establish a pulse output of a certain frequency when the two inputs are equal. In order to expand the operating band of the comparator-amplifier, an a-c voltage is introduced superimposed on the set point input. Over the operating band the output pulses from the comparator-amplifier are inversely proportional to the sensed temperature signal, and these pulses are used to control the application of electrical power to the heater.

대표청구항 ▼

In a system for controlling a parameter at a particular location, which has means operable to be activated for altering the parameter at the location, means, having an input, responsive to a control signal at the input for activating the parameter altering means, means, having an output, for sensing

In a system for controlling a parameter at a particular location, which has means operable to be activated for altering the parameter at the location, means, having an input, responsive to a control signal at the input for activating the parameter altering means, means, having an output, for sensing the parameter at the location and for producing a sensed parameter signal at the output, and a control circuit coupled to the output of the parameter sensing means and to a parameter set point signal and operable to produce an intermittent control signal, coupled to the input of the activating means, which is proportional to the difference between the two control circuit inputs, an improved control circuit comprising: a comparator circuit having a first input coupled to the output of the parameter sensing means and second input coupled to a parameter set point signal and having an output coupled to the input of the activating means; feedback means for conditioning the comparator circuit to produce an intermittent pulse signal at its output when its inputs are substantially equal; and means for coupling an a-c ripple voltage signal to one of the comparator inputs, said a-c ripple voltage supplied from an a-c source via a voltage attenuator such as a resistor to said one of the comparator inputs, whereby a band of values of the difference between the comparator inputs established by the amplitude of the a-c signal results in the production of an intermitten pulse signal at the output of the comparator with the pulse duration dependent upon said difference.