Digital bar graph tachometer
First Claim
Patent Images
1. A digital tachometer comprising:
- (a) a row of a plurality of closely adjacent light emitting diodes each representing, in order, an equal increment of speed;
(b) means to sense the rotational speed of rotating apparatus and develop a first signal representative thereof;
(c) means to convert said first signal into a plurality of signals of a maximum number equal to the number of said plurality of diodes, each associated with a diode and thus a speed increment such that a signal is present for each diode representing a speed equal to, or less than the sensed rotational speed;
(d) means coupling said plurality of signals to their associated diodes; and
(e) means to cause the next adjacent diode to the last one for which a signal is generated to blink when the sensed speed exceeds the value associated with said last one by at least one half the increment between diodes.
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Abstract
In order to provide a tachometer which is accurate and easy to read, a number of light-emitting diodes is arranged in a row, each diode representing a predetermined increment of speed, rotational speed is measured and used to generate pulses, at a proportional rate, which are then decoded and used to drive the light emitting diodes over a predetermined time span, the diodes being lighted repeatedly in sequence at a rate exceeding the response time of the eye so as to present a flicker-free bar graph type display showing rotational speed.
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Citations
34 Claims
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1. A digital tachometer comprising:
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(a) a row of a plurality of closely adjacent light emitting diodes each representing, in order, an equal increment of speed; (b) means to sense the rotational speed of rotating apparatus and develop a first signal representative thereof; (c) means to convert said first signal into a plurality of signals of a maximum number equal to the number of said plurality of diodes, each associated with a diode and thus a speed increment such that a signal is present for each diode representing a speed equal to, or less than the sensed rotational speed; (d) means coupling said plurality of signals to their associated diodes; and (e) means to cause the next adjacent diode to the last one for which a signal is generated to blink when the sensed speed exceeds the value associated with said last one by at least one half the increment between diodes. - View Dependent Claims (2, 3)
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4. A digital tachometer for an internal combustion engine comprising:
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(a) means for coupling to the engine to sense the firing of each cylinder thereof and develop a pulse in response thereto, thereby developing a pulse train; (b) means to multiply said pulse train to provide a second pulse train at a higher frequency in which, between each two sensed pulses, a plurality of pulses are developed; (c) a binary counter having said second pulse train as an input; (d) means to decode the output of said counter; (e) a row of closely adjacent light emitting diodes each representing, in order, an increment of speed having the outputs of said decoder as inputs; and (f) means for developing an enabling signal of fixed duration equal to the time between pulses on said first pulse train at a speed equal to that represented by the last diode in said row, said enabling signal coupled to enable said light emitting diodes. - View Dependent Claims (5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. Apparatus for providing an output representative of the frequency of a pulse train comprising:
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(a) a row of a plurality of closely adjacent light emitting diodes, each representing, in order, an equal increment of frequency; (b) means to convert said pulse train into a plurality of signals of a maximum number equal to the number of said plurality of diodes, each associated with a diode, and thus a frequency increment, such that a signal occurs for each diode representing a frequency equal to or less than the frequency being measured; (c) means coupling said plurality of signals to their associated diodes; and (d) means to cause the next adjacent diode to the last one for which a signal is generated to blink when the sensed frequency exceeds the value associated with said last one by at least one half the increment between diodes.
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17. Apparatus for measuring the frequency of a pulse train comprising:
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(a) binary counter having said pulse train as an input; (b) means to decode the output of said counter into a sequence of individual outputs of each present for an equal time; (c) a row of closely adjacent light emitting diodes each representing, in order, an increment of frequency having the outputs of said decoder as inputs; (d) means for developing an enabling signal of fixed duration equal to the total time for said counter to count a number of pulses on said pulse train, at a frequency equal to that represented by the last diode in said row corresponding to the maximum frequency, said enabling signal coupled to enable said light emitting diodes; and (e) means to multiply said pulse train to provide a second pulse train at a higher frequency in which, between each two sensed pulses, a plurality of pulses are developed, said second pulse train being fed to said binary counter whereby a pulse train at a frequency which would result in a flicker of said light emitting diodes which could be detected by the eye will be multiplied to a frequency which will not be detectable to the eye. - View Dependent Claims (18)
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19. Apparatus for measuring the frequency of a pulse train comprising:
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(a) binary counter having said pulse train as an input; (b) means to decode the output of said counter into a sequence of individual outputs each present for an equal time; (c) a row of closely adjacent light emitting diodes each representing, in order, an increment of frequency having the outputs of said decoder as inputs; (d) a one shot multivibrator having an output pulse length of fixed duration equal to the total time for said counter to count a number of pulses on said pulse train, at a frequency equal to that represented by the last diode in said row corresponding to the maximum frequency, said enabling signal coupled to enable said light emitting diodes; (e) a D type flip-flop having a clock input and data input and at least one output, the output of said one shot multivibrator coupled to the data input of said flip-flop and the output of the first stage of said binary counter to the clock input thereof, whereby, when said one shot multivibrator changes state, that change will not be reflected at the output of said D type flop-flip until the change at the output of the first stage of said counter, the output of said D type flip-flop being coupled as an enabling input to said light emitting diode array. - View Dependent Claims (20, 21, 23, 24)
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25. A method of displaying the frequency of a pulse train comprising:
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(a) disposing a plurality of light emitting diodes in closely adjacent relationship, each diode representing a predetermined frequency with successive diodes indicating successive frequency increments; (b) converting said pulse train into a plurality of signals of a maximum number equal to the number of said plurality of diodes, each signal associated with a diode and thus with a frequency increment up to a signal representing the sensed frequency; (c) coupling said plurality of signals to their associated diodes; and (d) causing the next adjacent diode to the last one for which a signal is generated to blink when the sensed frequency exceeds the value associated with said last diode by at least one half the increment between diodes. - View Dependent Claims (22, 26, 27, 28)
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29. A method of displaying the frequency of a pulse train comprising:
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(a) multiplying the pulse train to develop a further pulse train at a higher frequency; (b) disposing a plurality of light emitting diodes in closely adjacent relationship, each diode representing a predetermined frequency with successive diodes indicating successive frequency increments; (c) converting said further pulse train into a plurality of signals of a maximum number equal to the number of said plurality of diodes, each signal associated with a diode and thus with a frequency increment up to a signal representing the sensed frequency; and (d) coupling said plurality of signals to their associated diodes whereby, because of said multiplied pulse train, the appearance of flickering will be avoided. - View Dependent Claims (30, 31, 32)
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33. A method of displaying the frequency of a pulse train comprising:
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(a) multiplying said pulse train to provide a second pulse train at a higher frequency in which, between each two sensed pulses, a plurality of pulses are developed; (b) counting the pulses of said second pulse train in a counter; (c) decoding the output of the counter so as to provide a plurality of pulses, of equal duration in sequence for successive incremental counts of the counter; (d) disposing a plurality of light emitting diodes in closely adjacent relationship, the number of said diodes being equal to the number of individual pulses decoded; (e) coupling said decoded pulses to the associated ones of said light emitting diodes; and (f) enabling said light emitting diodes with an enabling signal having a duration which begins with the first count of said counter and extend over a period, during which period said counter would reach the last count thereof if the pulse train was at a predetermined maximum frequency to be measured, whereby a bar graph type display representing the measured frequency will be provided.
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34. Apparatus for measuring the frequency of a pulse train comprising:
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(a) binary counter having said pulse train as an input; (b) at least first and second decoders, at least one of said decoders having an enabling input, the output of the first M stages of said counter being coupled as inputs to said first decoder and the remaining stages as inputs to said second decoder, one of said decoders being constantly enabled and the other of said decoders having said enabling input, said decoders decoding the output of said counter into a sequence of individual outputs, each present for an equal time; (c) a row of closely adjacent light emitting diodes, each representing, in order, an increment of frequency, having the outputs of said decoder as inputs, said light emitting diodes arranged in a matrix such that each diode has one terminal coupled to an output of said first decoder and another terminal coupled to an output of said second decoder; and (d) means for developing an enabling signal of fixed duration equal to the total time for said counter to count a number of pulses on said pulse train, at a frequency equal to that represented by the last diode in said row corresponding to the maximum frequency, said enabling signal coupled to the enabling input of said one decoder to thereby enable said light emitting diodes.
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Specification