Boots – shoes – and leggings
Patent
1985-02-19
1988-03-22
Harkcom, Gary V.
Boots, shoes, and leggings
364551, G06F 762
Patent
active
047333642
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
TECHNICAL FIELD
The present invention relates to a period detecting circuit capable of detecting the speed of a mechanical apparatus such as a belt conveyor or the like by detecting the period of a pulse response to the speed thereof and particularly to a circuit which can detect ultra-low speed and hence the stopping of the apparatus.
BACKGROUND OF THE INVENTION
When detecting the rotary or revolutionary speed of a device, it is general that the period of a pulse generated by a pulse generator response to the rotational speed, be converted to a voltage which is indicated by the indicator of a tachometer, which indication can thereafter be read.
In the case, however, when the rotational speed becomes low, the period of the pulse becomes so long that the indicating needle of the indicating instrument of the tachometer vibrates and hence becomes difficult to read accurately. To avoid such shortcoming, it had been proposed to connect to the pulse generator, a capacitor having a large capacitance, but this causes a defect in that the response speed of the tachometer is lowered.
The present applicant has, therefore, the object of providing an apparatus of the type aforementioned which is free of such shortcoming.
FIG. 1 shows an example of the prior art. In the figure, a train of pulses PI each having period T corresponding to the rotational speed of the apparatus being detected and derived from a pulse generator is supplied via the input terminal 1 to a monostable multivibrator 2 from which a train of pulses PS (FIG. 2A) synchronized with the pulses PI is derived. This train of pulses PS is supplied to a second monostable multivibrator 3 from which a train of pulses PR (FIG. 2B) is derived, which are slightly delayed from the pulses PS. The pulses PR are supplied to a 1/T (T being the period) function generator 4 as a reset pulse signal. Derived from the 1/T function generator 4 is a downward sawtooth waveform output SA (FIG. 2C) which has a predetermined voltage E.sub.M cresting at the time when the function generator 4 is reset by a pulse RP and which falls from the peak voltage E.sub.M in a hyperbolic fashion within the period T of the input pulse PI until the arrival of the succeeding reset pulse. Accordingly, at the time point immediately before the function generator 4 is reset by the pulse PR, the output SA, namely, the crest value of the downward sawtooth wave in the figure is equal to the voltage corresponding to the period of the input pulse PI.
The output SA from the function generator 4 is supplied to a sampling gate circuit 6, to which the pulse PS from the first monostable multivibrator 2 is also supplied, through an OR gate 5, whereby the output SA is sampled by the pulse PS and the sampled voltage thereof is stored in a capacitor 7. Since each pulse PS is the pulse just before a reset pulse PR, the output sampled by the gate circuit 6 is the downward peak value voltage of the sawtooth wave voltage SA which corresponds to the period of the input pulse PI as mentioned before. This voltage SH.sub.O (shown by a solid line in FIG. 2D) is stored in the capacitor 7 and is supplied through a buffer amplifier 8 to an indicating instrument 9, the needle of which assumes a position corresponding to the voltage SH.sub.O.
Further, the output from the buffer amplifier 8 is supplied to a comparison circuit 10 to which the output SA from the function generator 4 is also supplied. This produces a compared output SC (FIG. 2E) which reaches a high level when the output SA becomes lower than the voltage SH.sub.O. This compared output SC is supplied through the OR gate 5 to the sampling gate circuit 6 so that during the period in which the output SC is at high level, the gate circuit 6 is opened. Thus, the voltage SH.sub.O of the capacitor 7 is changed along the output SA in hyperbolic fashion as shown by the solid line in FIG. 2D. The output SC of the comparison circuit 10 becomes high level when the rotational speed is lowered and the period of the input pulse PI becomes long. C
REFERENCES:
patent: 4306295 (1981-12-01), Caroc
patent: 4354239 (1982-10-01), Kanegae
patent: 4408296 (1983-10-01), Robbi et al.
patent: 4551813 (1985-11-01), Sanbayashi et al.
patent: 4575809 (1986-03-01), Sinniger et al.
Coco Research Inc.
Harkcom Gary V.
Herndon H. R.
Schaffer Murray
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