Temperature control apparatus for a centrifugal-type chemistry analyzer

Claim 1

A temperature control apparatus comprising a metal base member; a plurality of chambers adapted to contain liquid located within said base member in heat transfer relationship therewith, the thermal mass of the base member being substantially larger than the thermal mass of the thermal mass of liquid contained in the chambers; housing means substantially enclosing the base member and chambers to separate the base member and chambers from ambient temperature; a heating element adapted to develop heat by the passage of electrical current therethrough, means for passing air in contact with the heating element for the heating of said air and for introducing the heated air into the housing member to transfer heat developed in the heating element to the base member and chambers to raise the temperature thereof to a desired value; temperature sensing means adapted to provide an electrical signal proportional to the amount by which a selected chamber is below the desired value; control means responsive to the signal of the temperature sensing means adapted to supply electrical energy to the heating element; rate detecting means for obtaining an electrical signal proportional to the rate of temperature increase of the selected chamber and for applying such electrical signal to the control means to inactivate the control means when the rate oF temperature increase is above a predetermined value; means for preventing the signal from the rate detecting means from inactivating the control means as long as the temperature of the selected chamber is below a predetermined value.