| 摘要 |
A thermal flow sensor can adjust the temperature of a heating element in a highly precise and reliable manner with the use of simple circuits, devices and process steps. The sensor includes an amplifier section ( 7 ) that amplifies a voltage across opposite ends of at least one of resistors ( 3, 4, 5 ) that constitute a bridge circuit, a current control section ( 9 ) that is controlled based on an output voltage of the amplifier section ( 7 ), and an output terminal ( 14 ) that is connected to one end of a heating element ( 1 ) that is controlled to be energized by the current control section ( 9 ). The amplifier section ( 7 ) includes an amplification factor control section for controlling an amplification factor by an electric signal from a computer, and uses an output voltage which has been amplified and impressed to an input voltage to an operational amplifier ( 8 ).
|
