| 摘要 |
A one or multiple axis digital joystick using incremental optical encoding with mechanical means for magnifying motion of the encoded medium to achieve higher resolution than otherwise attainable with the same optoelectronic components. Excellent linearity between shaft rotation and digital output results from elimination of backlash and preservation of rotary-only motion in the mechanical linkage between shaft and encoder disc. All electronic functions are implemented in a low-cost internal microcomputer that interfaces in serial or parallel mode with many system computers or microcomputers without additional circuitry. The microcomputer converts the incrementally encoded signals from the optoelectronic devices into absolute shaft-position information in a fail-safe manner. The joystick can be operated very rapidly without error because the encoded pulses to be counted are applied to microcomputer inputs that store the occurrence of each pulse until the microcomputer can process them. The stored program also ensures that each joystick has the same full-scale outputs despite minor mechanical variations from one joystick to another. In addition, it corrects errors caused by hysteresis in some of the optoelectronic components. The resulting joystick is field replaceable without any adjustments or recalibration.
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