Browse Prior Art Database

Cordless Stylus for Ultraviolet Tablet

IP.com Disclosure Number: IPCOM000084071D
Original Publication Date: 1975-Sep-01
Included in the Prior Art Database: 2005-Mar-02
Document File: 3 page(s) / 47K

Publishing Venue

IBM

Related People

Ambrico, LE: AUTHOR [+3]

Abstract

Input tablets with associated light pens or styli are used as input devices to a processor, to generate vector messages to be transmitted to the processor using sampled position techniques. An input X-Y tablet system utilizes a stylus which is adapted to operate without being physically or electrically connected to the tablet.

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Cordless Stylus for Ultraviolet Tablet

Input tablets with associated light pens or styli are used as input devices to a processor, to generate vector messages to be transmitted to the processor using sampled position techniques. An input X-Y tablet system utilizes a stylus which is adapted to operate without being physically or electrically connected to the tablet.

Conventional ultrasonic tablets use vibrations set up by the stylus to create both longitudinal and transverse waves. One of these two waves is used for measurement purposes, and the interval between the stylus activation and the arrival of the longitudinal or transverse wave front at another location, knowing the wave velocity, is used to identify the position of the stylus in relation to a specific reference location. This practice makes the signal connection to the transmitting stylus essential, since the exact time of stylus activation is crucial.

The present device operates by measuring the time required for both the transverse and longitudinal waves to travel to a reference point from the coordinate location identified by the stylus. The transverse and longitudinal waves travel at known albeit different velocities, one of the waves being used to start a counter and the other to stop the counter, the contents of the counter then specifying the coordinate location of the stylus.

Referring to the drawing, the longitudinal wave generated by activation of the stylus passes through a bandpass filter 11 and an associated amplifier 13 to set latch trigger 15, the output of which is applied via line 17 to condition logic AND circuit 19, which in turn is sampled by the clock input from line 21 to start counter
23. The transverse signal also generated by the stylus is applied from line 25 through band-pass filter 27 and associated amplifier 29 to digitally-controlled analog switc...