of touchscreen 1 wave 14 may then be partially deflected by reflective elements 4 a thus the conventional wisdom is that transducer 20 should be positioned in the plane of the touchscreen or no more than moderately inclined with respect thereto but such positioning may not be feasible for a direct on crt for the reasons explained above in solving this problem we have discovered that it is possible to locate the transducers not on the frontal region but on the shoulder region of the crtf u2014 i e more or less on the side of the crt u2014 provided location parameters we have discovered are followed a direct on crt construction according to our invention is shown in fig5 a feature of our invention is positioning of the transmitting and receiving transducers 3 a 3 b 6 a and 6 b on shoulder region 17 as opposed to frontal region 16 because shoulder region 17 slopes away from frontal region 16 sometimes precipitously the transducers are positioned below the plane of frontal region 16 and do not mechanically interfere with a bezel not shown in this figure when it comes down on crt 15 fig6 is a cross section view showing schematically how such positioning avoids mechanical interference between transducer 4 and bezel 10 it is not sufficient to merely place a transducer on a shoulder region consider a transmitting transducer placed there the acoustic wave it generates.