Data processing system with a touch screen and a digitizing tablet, both integrated in an input device

DETAILED DESCRIPTION OF THE EMBODIMENTS Referring first to FIG.
7, the data processing system 200 of the present invention is seen to generally comprise a touch screen 10 for receiving a touch as by a user's finger 34, a digitizing tablet for interacting with a stylus 68 proximate thereto, first sensing means for sensing the presence and location of the touch within the area of the touch screen 10, and second sensing means for sensing the presence of stylus 68 above digitizing tablet 68 and its location within the tablet's area.
The first and second sensing means generate respective signals 206, 208 and feed them in parallel to data handling means 210.
FIG.
1 shows a first diagrammatic example of an input device for use in a data processing system according to the invention.
The input device comprises a layered structure with a touch screen 10 at the top, a digitizing tablet 12 in the middle and a liquid crystal display (LCD) 14 at the bottom.
For clarity the components constituting the layered structure have been drawn spaced out.
In practice, the structure is a compact laminated device.
Touch screen 10 operates on the basis of surface acoustic waves (SAW), radiated by transmitters 16 and 18 into a front panel 20 along respective series of reflective elements 22 and 24 in order to spread the transmitted waves across panel 20.
Panel 20 further is provided with receivers 26 and 28 that receive the waves after they have been reflected by respective other series of reflective elements 30 and 32.
A SAW-pulse transmitted by transmitters 16 or 18 will be received retarded and broadened by receivers 26 or 28.
In case a soft tissue, like a user's finger 34, contacts panel 20, some of the energy of the SAW-pulse will be absorbed by the tissue, resulting in a decreased amplitude of pulse components 36 and 38 passing through the location of contact 40.
The moment of the receipt of said reduced pulse components, related to the moment of transmission, is indicative of the momentary position 40 at which the absorption occurs