Physical Quantity Detection Device

A physical quantity detection device that detects at least one of a lateral acceleration and a lateral force that acts on a tire, using a strain sensor disposed in the tire, the physical quantity detection device comprising:

• a load detection/calculation unit that detects a load applied to the tire, from a negative peak value of a sensor signal waveform outputted by the strain sensor, the negative peak value changing on a negative side relative to a reference level resulting in a state where the tire is not in contact with a road surface;
• a lateral acceleration detection/calculation unit that determines the sensor signal waveform at the time of the tire's moving for traveling straight ahead and the sensor signal waveform at the time of the tire's moving for making a turn and that detects a lateral acceleration acting on the tire, from an amount of change of the negative peak value of the sensor signal waveform at time of the tire's moving for traveling straight ahead and the negative peak value of the sensor signal waveform at time of the tire's moving for making a turn, the negative peak value changing on the negative side relative to the reference level resulting in the state where the tire is not in contact with the road surface;
• and
• a lateral force detection/calculation unit that obtains a lateral force acting on the tire, from a product of the load detected by the load detection/calculation unit and the lateral acceleration detected by the lateral acceleration detection/calculation unit.