Patent ID: 7168312
Filing Date: 2007-01-30
Classification: G01F

Abstract:
1. A heating resistor type air flow meter comprising a heating resistor placed in an air flow passage, a heating current control circuit for controlling a heating current flowing through said heating resistor to maintain said heating resistor at a constant temperature, a flow rate sensing circuit for producing an air flow rate signal through the use of heating current control of said heating resistor, an output control circuit for amplifying and outputting said air flow rate signal, a temperature characteristic compensation circuit for compensating a temperature characteristic of said air flow rate signal whose output value varies with changes of temperature of the air flow meter circuitry, wherein said temperature characteristic compensation circuit comprises a circuit for producing a temperature characteristic signal for compensation which changes in response to changes in an ambient temperature, and a circuit for converting said temperature characteristic signal into a predetermined proportional signal, and wherein said predetermined proportional signal is added to said air flow rate signal and such an addition result signal is input to said output control circuit.