Patent ID: 7255011

Claim:
A resistance type sensor comprising: a detective member; a first electrode disposed on an X-axis so as to be opposed to the detective member; a second electrode disposed on a Y-axis so as to be opposed to the detective member; a third electrode disposed between the detective member and the first electrode so as to be opposed to the first electrode and displaceable toward the first electrode together with the detective member; a fourth electrode disposed between the detective member and the second electrode so as to be opposed to the second electrode and displaceable toward the second electrode together with the detective member; pressure-sensitive resistive materials disposed between the first and third electrodes and between the second and fourth electrodes; a plurality of first switch electrodes disposed so as to be opposed to the detective member and kept at a ground potential; and a plurality of second switch electrodes disposed so as to pair off with the respective first switch electrodes and be distant from the respective first switch electrodes, the second switch electrodes being kept at a potential different from the ground potential, each of the second switch electrodes being displaceable toward the corresponding first switch electrode to come into contact with the corresponding first switch electrode when the detective member is displaced, the sensor being able to detect displacement of a portion of the detective member corresponding to an X-axial direction on the basis of detection of a change in resistance value between the first and third electrodes, and to detect displacement of a portion of the detective member corresponding to a Y-axial direction on the basis of detection of a change in resistance value between the second and fourth electrodes, when at least one pair of first and second switch electrodes are distant from each other, the sensor being able to detect a central portion of the detective member on the basis of detection of a change in resistance value between the first and third electrodes and a change in resistance value between the second and fourth electrodes, when any pair of first and second switch electrodes are in contact with each other.