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Programmable Waveform Mechanical Oscillator

IP.com Disclosure Number: IPCOM000041962D
Original Publication Date: 1984-Mar-01
Included in the Prior Art Database: 2005-Feb-03
Document File: 2 page(s) / 51K

Publishing Venue

IBM

Related People

Flavin, RA: AUTHOR

Abstract

By using a stepper motor controlled cam, the fine motion of a cam follower can be digitally controlled. The oscillating motion of a moving mirror in an X-ray exposure system may be controlled using this concept. The coarse motion of the mechanical system is determined by the shape of the cam. Fine motion or changes and adjustments to the motion are accomplished by changing the rate at which the stepper motor is stepped. The rate at which the motor is stepped is controlled by a digital system. The digital system contains a memory which determines the period for each step. If the period for a step (or a group of steps) is lengthened, then the velocity of the motor and the velocity of the driven part (such as a mirror) are reduced.

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Programmable Waveform Mechanical Oscillator

By using a stepper motor controlled cam, the fine motion of a cam follower can be digitally controlled. The oscillating motion of a moving mirror in an X-ray exposure system may be controlled using this concept. The coarse motion of the mechanical system is determined by the shape of the cam. Fine motion or changes and adjustments to the motion are accomplished by changing the rate at which the stepper motor is stepped. The rate at which the motor is stepped is controlled by a digital system. The digital system contains a memory which determines the period for each step. If the period for a step (or a group of steps) is lengthened, then the velocity of the motor and the velocity of the driven part (such as a mirror) are reduced. For the X-ray mirror drive system, the dose of X- rays increases as the beam dwells longer in one area. If the step period is shortened, the mirror velocity increases, and the exposure dose is reduced. In this manner, the motion of a mechanical system (such as a mirror) can be accurately adjusted in time. The X-ray mirror drive system is illustrated in Fig. 1. Fig. 2 shows a triangular waveform representing the angle of the mirror as a function of time for uniform drive motor velocity. By decreasing the step period for steps in region "B" of each cycle, and lengthening the step period in regions "A" and "C" of each cycle, the motion of the mirror with respect to time can be adjusted as shown in...