INVESTIGATION OF AN ANALOG TECHNIQUE TO DECREASE PEN-TRACKING TIME IN COMPUTER DISPLAYS.
MASSACHUSETTS INST OF TECH CAMBRIDGE PROJECT MAC
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Through the use of a CRT display and a light-sensitive pen, graphical material can be directly inserted into a computer by using the pen to control the position of the electron beam at the face of the CRT - a process called pen tracking. To reduce tracking time, an analog technique employing a four-point tracking pattern is proposed in this study, in which the amplitude response of the pen to corresponding pairs of points is used to determine the position of the pen relative to the center of the pattern. To study the method, one channel of the proposed two -channel analog tracking system was designed, constructed, and coupled to the horizontal channel of the Project MAC - ESL display console. To avoid the phosphor-decay limitation, an experimental beam pen capable of detecting the electron beam rather than the phosphor luminescence was employed. The system includes a pattern generator, sample-and-hold gates, difference amplifier, envelope detector and noise filter, and a threshold-logic analog-to-digital converter. Author
- Information Science
- Computer Hardware
- Human Factors Engineering and Man Machine Systems
- Non-Radio Communications