Patent ID: 8636409

Claim:
A heat treatment apparatus comprising: a furnace body including a heating part disposed at an inner circumference surface thereof; a processing vessel disposed in the furnace body, and configured to receive a plurality of objects to be processed, wherein a space having a plurality of regions is formed between the furnace body and the processing vessel; an in-furnace temperature sensor disposed corresponding to each of the plurality of regions in the space, wherein the plurality of regions includes a reference region and other region; an in-furnace temperature calculating unit configured to calculate an in-furnace temperature based on signals from each of the in-furnace temperature sensors; and a control unit configured to control the heating part based on the in-furnace temperature calculated by the in-furnace temperature calculating unit, wherein the in-furnace temperature sensor disposed in the reference region includes: a first thermocouple formed of an R thermocouple or an S thermocouple; and a second thermocouple formed of a thermocouple other than the R thermocouple or the S thermocouple, wherein the in-furnace temperature sensor disposed in the other region includes the second thermocouple, and the other region corresponds to the plurality of regions excluding the reference region, and wherein the in-furnace temperature calculating unit includes: an electromotive force difference circuit connected to the second thermocouple in the reference region and the second thermocouple in the other region, and configured to calculate a temperature difference between the reference region and the other region; a first thermocouple electromotive force measurement circuit connected to the first thermocouple in the reference region, and configured to calculate a temperature in the reference region based on a first signal from the first thermocouple; and an adder connected to the first thermocouple electromotive force measurement circuit and the electromotive force difference circuit corresponding to the other region, and configured to add a second signal from the first thermocouple electromotive force measurement circuit to a third signal from the electromotive force difference circuit to calculate a temperature in the other region.