Patent ID: 6990435

Claim:
A method for detecting tactile information on touch force acting on measurement points, based on outputs from bridge circuits constituted by strain gauges adhered to each measurement point, comprising: generating a composite sine wave signal that contains sine wave components having different frequencies; applying the composite sine wave signal to each bridge circuit via a bandpass filter to apply to each bridge circuit a sine wave signal of a predetermined single frequency; adding outputs from each bridge circuit to generate a sum output; from the sum output, utilizing trigonometric function orthogonality to obtain at least touch force of touch force and touch direction acting on each measurement point; comparing voltage amplitude measured at each measurement point to a reference voltage preset for each measurement point and adjusting the voltage amplitude of the sine wave signal of each frequency applied to the bridge circuit of each measurement point to control the gain of the bridge circuit of each measurement point to reduce any difference between measured and reference voltages.