Seikou Suzuki

Accelerometer with pulse width modulation

An accelerometer having a movable electrode which is moved according to acceleration with respect to a fixed electrode disposed in opposition to the movable electrode. An output device generates an output voltage which is proportional to the acceleration by measuring a gap between the movable electrode and the fixed electrode. A pulse width modulator generates pulses, wherein a pulse width of the pulses is modulated according to the output voltage, and a feedback device feeds back an electrostatic force which is proportional to the pulse width of the pulses from the pulse modulator between the movable electrode and the fixed electrode. As the acceleration in the acceleration sensor is linearly detected, the acceleration sensor is easily adjusted.

Motion investigation of electrostatic servo-accelerometers by means of transparent ITO fixed electrodes

The authors introduce a novel thin film material for sensors and actuators: indium tin oxide (ITO). ITO has the unique feature of combining low electrical resistivity and high visual transparency. Thin ITO films were deposited by DC-sputtering to form the fixed electrodes of a capacitive servo-accelerometer. Since the movable electrode of the accelerometer is visible during real operation of the sensor, its behavior can be studied under various conditions. One investigation presented is a study of the motion of the movable electrode at high electrostatic voltages, and its effect on the measurement range of the sensor. The benefits of ITO for mass production are illustrated by means of the evaluation of the temperature behavior of the accelerometers.<<ETX>>