Method and apparatus for driving air core meter movements
First Claim
1. Circuitry for providing, in response to a periodic input signal of variable frequency, first and second output signals suitable for driving an air core meter means to provide a meter deflection indicative of the frequency of the input signal, comprising:
- means, responsive to the input signal, for providing first and second signals which are respectively representative of cosine and negative sine waveforms, and which have a predetermined phase relationship with the input signal;
means, responsive to the input signals, for providing a pulse signal having a duration which is determined by the period of the input signal;
means for applying a reference signal to the meter for the duration of the pulse signal;
means for defining an aperture interval following the end of said pulse signal; and
means for applying the first and second waveforms to the meter during the aperture interval.
1 Assignment
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Accused Products
Abstract
Method and circuitry for generating signals in response to an input signal whose frequency or pulse rate is to be measured, which signals are directly applicable to the coils of an air core type meter movement or the like to provide an output indication of the frequency or pulse rate of the input signal. The signals applied to the air core meter are generated directly from the input signal and include sine and cosine signals synchronous with the input signal. A preferred embodiment is disclosed which includes circuitry which produces staircase waveforms, which when integrated, produce the required sine and cosine signals to drive an air core meter movement in response to a periodic input signal.
13 Citations
19 Claims
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1. Circuitry for providing, in response to a periodic input signal of variable frequency, first and second output signals suitable for driving an air core meter means to provide a meter deflection indicative of the frequency of the input signal, comprising:
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means, responsive to the input signal, for providing first and second signals which are respectively representative of cosine and negative sine waveforms, and which have a predetermined phase relationship with the input signal; means, responsive to the input signals, for providing a pulse signal having a duration which is determined by the period of the input signal; means for applying a reference signal to the meter for the duration of the pulse signal; means for defining an aperture interval following the end of said pulse signal; and means for applying the first and second waveforms to the meter during the aperture interval. - View Dependent Claims (4, 5, 6, 7, 8, 9)
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2. Circuitry for providing, in response to a periodic input signal of variable frequency, first and second output signals suitable for application to an air core meter means, having first and second input terminals, to provide an output indication of the frequency of the input signal, comprising:
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means, responsive to the input signal, for defining an initialization period having a duration determined by the frequency of the periodic input signal; means, responsive to the input signal, for providing first and second signals representative of cosine and inverted sine waveforms synchronous with the periodic input signals; means for defining an aperture period following said initialization period; means for applying a reference signal to the second input terminal during the initialization period; means for applying the first signal to the first input terminal and for applying the second signal to the second input terminal during the aperture period; and means for controlling the above-mentioned means to cause the circuitry to repetitively define initialization and aperture periods in response to the input signal so as to provide the first and second output signals representative of the frequency of the periodic input signal.
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3. Circuitry responsive to a periodic input signal of variable frequency for providing first and second output signals of the frequency of the input signal, comprising:
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first and second terminals at which the first and second output signals are provided; means, responsive to the input signal, for providing first and second signals which are respectively representative of cosine and negative sine waveforms, and which have a predetermined phase relationship with the input signal; means, responsive to the input signal, for providing a pulse signal having a duration which is determined by the period of the input signal; means for applying a reference signal to the second terminal for the duration of the pulse signal; means for defining an aperture interval following the end of said pulse signal; and means for applying the first and second waveforms to the first and second terminals respectively during the aperture interval.
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10. Apparatus for providing, in response to a periodic input signal of variable frequency, first and second output signals suitable for driving an air core meter to produce a meter deflection indicative of the frequency of the input signal, comprising:
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first and second output terminals at which the first and second output signals are respectively provided; timer means responsive to input signal for providing a pulse signal of a predetermined duration to said terminals; means responsive to the pulse signal and to the input signal for providing sine and cosine staircase approximation signals which vary in frequency in accordance with the frequency of the input signal, including; a counter having a clock input and having a plurality of outputs which are sequentially activated in response to signals applied to the clock input; means for applying the periodic input signal to the counter clock input; a first plurality of resistors connecting selected ones of the counter outputs to the first amplifier circuit, the first plurality of resistors having values so as to provide an output signal from the first amplifier circuit which is a staircase approximation of a negative sine wave as the counter is incremented by signals applied to the counter clock input; a second plurality of resistors connecting selected ones of the counter outputs to the second amplifier circuit, the second plurality of resistors having values so as to provide an output signal from the second amplifier circuit which is a staircase approximation to a cosine waveform as the counter is incremented by signals applied to the counter clock input; and a resistor connecting one of said counter outputs to the first amplifier circuit for applying thereto an initial pulse signal of a predetermined amplitude for a period determined by the frequency of the input signal; and switching means responsive to the timer means output signal for applying the output signals from the first and second amplifier circuits to the first and second output terminals respectively following the initial pulse signal. - View Dependent Claims (11, 12, 13, 14)
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15. A method for providing, in response to a periodic input signal of variable frequency, first and second output signals suitable for application to an air core meter means, having first and second input terminals, to provide an output indication of the frequency of the input signal, comprising the steps of:
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defining an initialization period having a duration determined by the frequency of the periodic input signal; providing first and second signals respectively representative of cosine and negative sine waveforms synchronous with the periodic input signal; defining an aperture period following the initialization period; applying a reference signal to the second input terminal during the initialization period; applying the first signal and the second signal to the first and second input terminals during the aperture period; and repetitively defining initialization and aperture periods in response to the input signal so as to provide the first and second output signals representative of the frequency of the periodic input signal. - View Dependent Claims (17, 18, 19)
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16. A method for providing, in response to a periodic input signal of variable frequency, first and second output signals indicative of the frequency of the input signal, comprising the steps of:
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providing first and second signals which are respectively representative of cosine and negative sine waveforms, and which have a predetermined phase relationship with the input signal; providing a pulse signal having a duration which is determined by the period of the input signal; applying a reference signal to a first output terminal for the duration of the pulse signal; defining an aperture interval following the end of said pulse signal; and applying the first and second waveforms to a second output terminal during the aperture interval.
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Specification