Tachometer
First Claim
1. In a tachometer:
- a rotating member, first means for providing an first electrical signal indicative of the speed of rotation of the member, second means responsive to the first electrical signal for providing successive digital signals representative of the speed of rotation during successive time intervals, third means for averaging the successive digital signals and providing an average value, storage means for storing the average value, fourth means for comparing the most recent digital signal with the average value and updating the stored average with the most recent signal if the difference between the average value and the most recent signal is less a predetermined amount or alternately replacing the stored average with the most recent digital signal if the difference is greater than or equal to the predetermined amount, and fifth means responsive to the contents of the storage means for providing an output signal indicative of the speed of rotation of the member.
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Accused Products
Abstract
A tachometer for monitoring several functions on an implement, such as engine, shaft and ground speeds. A microprocessor receives a-c input signals which vary in frequency as the shaft or ground speeds change. A time window synchronized with a rising edge on the desired input signal is provided during which the number of falling edges are counted. A running total weighted average of a number of successive counts is used to update a digital readout indicating speed. Each new count is compared with the previous average and, if a sudden speed change occurs, the processor shifts to a fast update mode in which the new count is used to immediately update the readout. Programming switches are provided for selecting the proper ground speed time window for a given tire size and for providing a ground speed indication in either kilometers per hour or miles per hour.
38 Citations
53 Claims
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1. In a tachometer:
- a rotating member, first means for providing an first electrical signal indicative of the speed of rotation of the member, second means responsive to the first electrical signal for providing successive digital signals representative of the speed of rotation during successive time intervals, third means for averaging the successive digital signals and providing an average value, storage means for storing the average value, fourth means for comparing the most recent digital signal with the average value and updating the stored average with the most recent signal if the difference between the average value and the most recent signal is less a predetermined amount or alternately replacing the stored average with the most recent digital signal if the difference is greater than or equal to the predetermined amount, and fifth means responsive to the contents of the storage means for providing an output signal indicative of the speed of rotation of the member.
- View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A speed measuring device comprising;
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means for providing an a-c electrical signal having a frequency proportional to speed, means for establishing a succession of clock periods, means for counting the number of electrical signal cycles occurring during a clock period and providing a digital signal indicative thereof; means for weighting a plurality of the digital signals and providing a weighted average signal therefrom, display means selectively responsive to the digital signal or the weighted average signal for providing an indication of the speed, means for comparing the weighted average signal with the most recent digital signal and selecting the display means to be responsive to the weighted average signal including the most recent digital signal if the most recent digital signal differs by less than a predetermined amount from the compared weighted average, or alternatively selecting the display means to be responsive to the most recent digital signal if it differs by more than the predetermined amount from the compared weighted average. - View Dependent Claims (9, 10)
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11. An instrument for measuring speed of a device, comprising:
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speed responsive means for providing an a-c signal having a frequency proportional to the speed of the device, means for providing time windows; means for providing a speed indicative signal responsive to the frequency of the a-c signal during the time window; averaging means for receiving and averaging successive speed indicative signals and providing an average value signal; display register means for selectively receiving the average value signal or the speed indicative signal; means for comparing the average value signal with the most recent speed indicative signal and transmitting said most recent speed indicative signal to the averaging means for providing an updated average value signal to the display register means if said average value and most recent speed indicative signals differ by less than a predetermined amount or, alternately, if said average value and most recent speed indicative signals differ by more than the predetermined amount, entering said most recent speed indicative signal into the display register means; and indicator means responsive to the contents of the display register means for providing an indication of the speed of the device. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. An instrument for determining the speed of several devices, comprising:
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first means for sensing movement and providing a plurality of first electrical signals indicative of the speeds of the devices; processor means having a plurality of inputs connected to the first means for selectively monitoring one of the first signals, said processor means further including; timing means for providing timing windows, means responsive to the selected first signal for providing speed signals indicative of the speed of the device corresponding to the selected first signal during the timing window, means for averaging a plurality of the speed signals and providing an average value signal, display means selectively responsive to a digital signal or an average value signal for providing a speed indication therefrom, and means for comparing the average value signal and the latest speed signal provided during the most recent timing window and selecting the display means to be responsive to said latest speed signal if the difference between said latest speed signal and the average value signal is above a preselected value, or the average value signal if the difference is below the preselected value. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31)
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32. In a speed measuring device including a speed sensor for providing an input signal indicative of the speed to be measured, means responsive to the input signal for providing speed signals during successive time intervals, and display means responsive to the speed signals for providing an indication of the measured speed, the improvement comprising:
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means for providing a running total weighted average, An of successive speed signals according to the equation;
space="preserve" listing-type="equation">A.sub.n =1/4[X.sub.n +3/4X.sub.n-1 +(3/4).sup.2 X.sub.n-2 +(3/4).sup.3 X.sub.n-3 . . . ]where Xn is the speed signal during the most recent time interval, n, means for comparing the most recent speed signal Xn with the previous running total weighted average An-1, and wherein the display means is responsive to the average An when the difference between Xn and and An-1 is less than a preselected value and to the signal Xn when the difference is greater than the preselected value.
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33. In a speed measuring device including a speed sensor for providing an input signal indicative of the speed to be measured, means responsive to the input signal for providing speed signals during successive time intervals, and display means responsive to the speed signals for providing an indication of the measured speed, the improvement comprising:
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means for providing a running total weighted average, An, of successive signals according to the equation;
space="preserve" listing-type="equation">A.sub.n =1/4[X.sub.n +3/4X.sub.n-1 +(3/4).sup.2 X.sub.n-2 +(3/4).sup.3 X.sub.n-3 . . . ]wherein Xn is the speed signal during the most recent time interval n, and acceleration responsive means for determining the rate of change of the speed, said display means selectively responsive to the average An when the rate of change is below a preselected rate and to the speed signal Xn when the rate of change is above the preselected rate.
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34. In a speed measuring device including a transducer for providing a pulse signal the frequency of which is indicative of the speed to be measured, window generating means for providing time windows, counter means for counting the number of pulses occurring during a time window, and display means responsive to the count of the counter means for providing an indication of the speed, the improvement comprising:
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memory means for storing a plurality of timing signals each representing a predetermined period of time; programmable switch means for selecting one of the timing signals from the memory means; and wherein said window generating means is responsive to the timing signal selected by the programmable switch means to provide a time window of a length equal to the period of time represented by the selected signal. - View Dependent Claims (35, 36, 37)
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38. A device for providing a measurement of the speed of a moving member, comprising:
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signal generator means for providing a pulse signal having a pulse rate proportional to the speed of the member, clock means for providing successive time intervals, counter means for counting the number of pulses occurring during the time intervals, means responsive to the count of the counter means for providing an average value signal indicative of an average count per time interval during a plurality of time intervals, acceleration responsive means for determining if acceleration of the moving member exceeds a preselected limit or is less than the preselected limit, display means automatically responsive to the count of the counter means when the acceleration exceeds the preselected limit and to the average value signal when the acceleration is less than the preselected limit for providing an indication of the speed of the member. - View Dependent Claims (39)
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40. A speed measuring device comprising:
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first means for providing speed signals representative of the speed to be measured; second means responsive to the first means for providing an average value signal representative of the average value of the speed signals; third means responsive to the speed signals for providing an acceleration indication; display means associated with the first, second and third means selectively responsive to the average value signal when the indicated acceleration is below a preselected value and to the speed signals when the indicated acceleration is above the preselected value for providing an indication of the speed. - View Dependent Claims (41, 42, 43)
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44. A method of measuring the speed of a device, including the steps of:
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providing first speed signals indicative of the speed of the device during successive time intervals; providing an average value signal indicative of the average value of the speed of the device; determining if acceleration of the device is above or below a preselected level of acceleration; outputting to a user device an indication of the average value signal if the acceleration is below the preselected value, or alternatively, outputting to the user device an indication of one of the first speed signals if the acceleration is above the preselected value. - View Dependent Claims (45, 46, 47)
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48. A methd of measuring the speed of a driven device wherein the speed is a function of both angular velocity of a drive shaft and size of a driven member, the method including the steps of:
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providing a plurality of successive clock periods; adjusting the length of the clock periods in accordance with the size of the driven member; providing pulses the frequency of which is dependent on the angular velocity of the drive shaft; counting the number of pulses occurring during each clock period; and providing an indication of the speed from the pulse counts. - View Dependent Claims (49, 50)
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51. A method for measuring the speed of a device, including the steps of:
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providing a plurality of clock periods; providing pulses the frequency of which are dependent on the speed of the device; counting the number of pulses occurring during each clock period to provide a first speed signal for each period; averaging the pulse counts for a plurality of clock perids to provide an average speed signal; comparing the average speed signal with the first speed signal; providing a speed indication responsive to the most recent first speed signal if the difference between the compared average and first speed signals is greater than a preselected limit, or alternatively, providing a speed indication responsive to the average speed signal if the difference is less than the preselected limit. - View Dependent Claims (52, 53)
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Specification