Open loop control for spectrophotometer atomizer furnace

Claim 1

Heating apparatus for spectrophotometric analysis apparatus comprising: an electrical power source, a resistive heating element arranged to generate heat by being supplied as electrical energy from the power source, said power source being variable to enable control of the energy supply to the element, thereby controlling its temperature, and a control circuit operable to determine the total energy required to monotonically change the temperature of the element from an initial temperature to a selectable final temperature at a particular selectable rate, said total energy being dependent on the energy input to the heating element required to maintain the heating element at a constant temperature and also being dependent on said particular rate of element temperature change, said control circuit including storage means for storing data relating the heating element temperature within a temperature range to the energy input to the heating element at a constant temperature, both said initial temperature and said selectable final temperature falling within said temperature range, and said control circuit being operable to determine said total energy in part from said data in said storage means, and in part from the selected said particular rate of element temperature change, said control circuit being operable to generate an output signal representative of said total energy and to which the power source is responsive so as to control the energy supply by the power source to the heating element.

Claim 10

A method for controlled heating of a sample for spectrophotometric studies, to raise the temperature of said sample as a desired monotonic function of time from an initial temperature to a final temperature in an open loop regime, comprising the steps of determining a first component of electrical power for thermal dissipation to the sample at its surrounds, said first component comprising the quantity of electrical power required to maintain said initial temperature of said sample and its surrounds, and applying said first component to said sample at its surrounds, assertaining a second component of electrical power, additive to said first component, said second component comprising the quantity of electrical power required to raise the temperature of said sample at its surrounds to said final temperature at a desired rate dT/dt and applying said second component to said sample at its surrounds.

Claim 11

A method for controlled heating of a sample for spectrophotometric studies, to raise the temperature of said sample as a desired monotonic function of time from an initial temperature to a final temperature in an open loop regime, comprising the steps of determining a first component of electrical power for thermal dissipation to the sample at its surrounds, said first component comprising the quantity of electrical power required to maintain said initial temperature of said sample and its surrounds, and applying said first component to said sample at its surrounds, assertaining a second component of electrical power, additive to said first component, said second component comprising the quantity of electrical power required to raise the temperature of said sample at its surrounds to said final temperature at a desired rate dT/dt and applying said second component to said sample at its surrounds.