APPARATUS FOR DETECTING VARIATION OF CAPACITANCE

摘要

A capacitance variation detecting device is provided to prevent malfunction although a touch pad is separated far apart, by recognizing capacitance variation through difference frequency between two channels. A capacitance variation detecting device is composed of a reference frequency storing unit(12) connected with a reference input line to store reference frequency(fa) inputted from the reference input line; a touch frequency storing unit(14) connected with a sensing input line to store touch frequency(fb) inputted from the sensing input line; a difference frequency calculation unit(20) for computing difference frequency(fd); a unit(30) for generating reference difference frequency(fr); a unit(40) for calculating difference frequency change rate(fd(t)-fr(t-1)); and a comparing unit(50) comparing the predetermined sensing level and the difference frequency change rate obtained from the difference frequency change rate calculating unit and generating output if the difference frequency change rate is over the predetermined sensing level.