Abstract: An ultrasonic coordinate input, apparatus comprising a plurality of ultrasonic wave receivers to receive ultrasonic wave emitted by a cordless ultrasonic pen and propagating in an ultrasonic propagating medium, a plurality of receiving circuits for detecting the rising edges of received signals of the ultrasonic wave receivers, a measuring circuit for measuring the difference in time of receiving ultrasonic wave between the ultrasonic wave receivers and a calculating circuit for calculating the coordinates of ultrasonic wave input position according to the result of measurement. When the receiving circuits, the measuring circuit and the calculating circuit are installed together with the ultrasonic wave receivers on the ultrasonic propagating medium, the entire apparatus can be made small in size.

Abstract: An earthquake-proof leg support structure (10) of an electronic apparatus comprising a leg (12) vertically downwardly extending from the outer case (1) and a dish-shaped leg support seat (20) to receive the leg (12). The leg support seat (20) includes a metal element (28) having an upper surface (22) over which the leg (12) slides and a peripheral flange (24) against which the leg (12) abuts, and a plastic liner (30) having a lower flat smooth surface (26) which is slidable on the floor. The lower end surface (14) of the leg is of a convex spherical shape and the upper surface (22) of the leg support seat includes a central surface portion (22a) of a concave spherical shape and a cone-shaped slope portion (22b) arranged around and tangential to the central surface portion, with the radius of curvature of the leg (12) being smaller than that of the upper surface (22) of the leg support seat (20 ).