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DRIVE-CONTROL COMPONENTS- ABS
The semiconductor strain gauge type sensor, constructed as
Piezo diffusion shown at the left, consists of a weight mounted at the free
resistor Weight end of an N-type silicon leaf spring, and four P-type diffusion
L layers made on the surface of the leaf spring to constitute
Damping piezo diffusion resistors. The case is filled with a damping
oil oil to prevent breakdown that may be caused by resonance.
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Bridge circuit The piezo diffusion resistors, arranged as shown at the left,
complete a bridge circuit which constitutes a semiconductor
strain gauge.
Piezo diffusion When the sensor is placed under strain by acceleration, the
resistor piezoelectric effect changes its electrical resistance, causing
the bridge circuit to go out of balance.
If a voltage is applied across the bridge circuit, the acceleration
can be measured by detecting the amount the bridge circuit
goes out of balance in terms of a change in the voltage.
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The output characteristics vary as shown at the left in the
output Output voltage (V) direction of acceleration with 2.5 V as 0 G.
characteristics I
I, /y(G)
-0.1 0 1.0
Accele- - Rate of - Decele-
ration acceleration ration
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L