Graf/Pen
Graf/Pen is a line of 3D input devices from Science Accessories. It was invented by Albert Whetstone.[1] The original Graf/Pen was 2D, but they eventually became 3D.
The simplest Graf/Pen devices are 2D devices.
Graf/Pen senses the position of a handheld pen by timing the propagation of sound between a source at the tip of the pen and sensors around a tablet.[1] The sound source is simply a spark. Because a spark produces sound very efficiently, the stored energy in the spark can be so low that it is impossible to feel it even when it is covered with the finger of the operator.[1]
Original development[edit]
The original Graf/Pen was presented and patented in 1969.[2] In 1969, one of the intended uses was for interactive computer graphics. The original patent covered a 3D variant.
The original Graf/Pen's sensors were microphones in which the moving element is aluminized mylar foil.[1]
The digitizing process for 2D is as follows: X and Y counters begin counting the clock pulses after a short delay which follows the sparking time. The delay permits adjustment of the margin of the digitizing area. After the counters stop and the contents come to rest an Output Ready pulse is generated to be used as a Program Interrupt or Punch Command.[1] In the original system, coordinate pairs could be generated at rates up to 200 per second.
The original system used 10-bit binary counters to cover an active tablet of 14 inches square. This corresponds to a resolution of 1000 x 1000.[1]
The pen contained an actual pen with ball point refills.[1]
In the original system, all of the digitizing electronics were integrated circuits.[1]
Graf/Pen was intended to be used for applications that did not yet exist at the time of its invention.[1]
Whetstone gave credit to Bill Banks, Sam Fine, Gary Jackson, Stan Phillips, and Ed Snyder.[1]
In the three dimensional form of the invention, each microphone is arranged along an appropriate axis and in the form of a sheet encompassing the desired area. Each microphone is provided with a digitizing channel.[2]
References[edit]
- ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 Whetstone, Albert L. (1969). "Graf/Pen". ACM Press. p. 369–376. doi:10.1145/800165.805250. https://dl.acm.org/doi/pdf/10.1145/800165.805250.
- ↑ 2.0 2.1 "Graphical data device". 1969-07-11. https://patents.google.com/patent/US3838212A/en.