Linear readout flowmeter

Claim 2

Apparatus for determining the speed of a moving substance, comprising: means for measuring the time elapsed for the substance to travel a fixed distance; and means coupled to said time measuring means for generating a speed signal representing the inverse of the elapsed time, said signal being linearly related to the speed of the substance and convertible into a speed indication, said speed signal generating means including means for generating a pulsating signal having a duty cycle directly proportional to the elapsed time.

Claim 3

The apparatus of claim 1 wherein said speed signal generating means includes computing means responsive to said pulsating signal for generating the speed signal, said speed signal having an average magnitude inversely proportional to said duty cycle.

Claim 4

The apparatus of claim 1 including means responsive to the speed signal to provide an indication of speed and wherein said speed signal generating means includes an integrator circuit coupled between said pulsating signal generating means and said speed indicating means.

Claim 5

The apparatus of claim 3 wherein said pulsating signal has a fixed frequency and alternates between first and second states during each period thereof, said duty cycle being the percentage of time that said pulsating signal is in said first state during each period, said integrator circuit has an input and an output for providing said speed signal, and said speed signal generating means includes means for coupling the integrator circuit output to the integrator circuit input, a source of reference potential, and switch means for shorting said integrator circuit input to said reference potential in response to said pulsating signal assuming said second state.

Claim 6

The apparatus of claim 4 wherein said integrator circuit comprises an operational amplifier having an inverting input, a normal input and an output, a first impedance means coupling the normal input to the reference potential, a capacitor coupling the amplifier output to the inverting input, said amplifier output comprising said circuit output, a second impedance means coupling a fixed voltage, negative with respect to said reference potential, to the inverting input and capacitor, and a third impedance means coupling the circuit input to the inverting input.

Claim 7

The apparatus of claim 3 wherein said pulsating signal alternates between first and second states during each period thereof, said duty cycle being the percentage of time that said pulsating signal is in said first state during each period, said integrator circuit having an output for producing said speed signal, the magnitude of the speed signal at the end of each second state pulse being represented by, S1,n 1 So,n - K1 t1 where: S1,n 1 + the magnitude of the speed signal at the end of the N + 1st second state pulse of the pulsating signal, So,n the magnitude of the speed signal at the end of the Nth first state pulse immediately preceding the Nth second state pulse, K1 a negative constant t1 the pulse width of the second state pulse, and the magnitude of the speed signal at the end of each first state pulse being represented by, where: So,n 1 the magnitude of the speed signal at the end of the N + 1st first state pulse of the alternating signal, S1,n the magnitude of the speed signal at the end of the Nth second state pulse immediately preceding the beginning of the Nth first state pulse, t2 pulse width of the first state pulse, K3 a negative constant K2, K4, K5 positive constants.

Claim 8

Apparatus for determining the speed of a moving substance, comprising: means for measuring the time elapsed for the substance to travel a fixed distance including means for generating a signal having a magnitude directly proportional to the elapsed time, start and stop detectors spaced apart said fixed distance along the path of motion of said moving substance, a timing means including a timing capacitor, a timing constant current source, means for coupling said timing current source to said timing capacitor to charge the capacitor linearly in response to said substance being detected by said start detector and uncoupling said timing current source from said capacitor in response to said substance being detected by said stop detector, the charge across the capacitor having a magnitude directly proportional to the elapsed time, the voltage across said capacitor decreasing due to polarization losses immediately after said timing current source is uncoupled therefrom, and said timing means including compensating means for keeping said voltage at a constant voltage level equal to the voltage level at the time of uncoupling; and means coupled to said time measuring means for generating a speed signal representing the inverse of the elapsed time, said signal being linearly related to the speed oF the substance and convertible into a speed indication.

Claim 9

Apparatus for determining the speed of a moving substance, comprising: means for measuring the time elapsed for the substance to travel a fixed distance including means for generating a signal having a magnitude directly proportional to the elapsed time, start and stop detectors spaced apart said fixed distance along the path of motion of said moving substance, a timing means including a timing capacitor, a timing constant current source, means for coupling said timing current source to said timing capacitor to charge the capacitor linearly in response to said substance being detected by said start detector and uncoupling said timing current source from said capacitor in response to said substance being detected by said stop detector, the charge across the capacitor having a magnitude directly proportional to the elapsed time, the voltage across said capacitor decreasing due to polarization losses immediately after said timing current source is uncoupled therefrom, and said timing means including compensating means for keeping said voltage at a constant voltage level equal to the voltage level at the time of uncoupling; and means coupled to said time measuring means for generating a speed signal representing the inverse of the elapsed time, said signal being linearly related to the speed oF the substance and convertible into a speed indication.

Claim 10

The apparatus of claim 7 wherein said compensating means includes a compensating current source, a switch for coupling the compensating current source with the timing capacitor and a compensating capacitor connected across the switch, said switch turning on in response to the substance being detected by the start detector to conduct a small portion of the total charging current for the timing capacitor from the compensating current source and turning off in response to the substance being detected by the stop detector, said compensating capacitor conducting a compensating charging current from the compensating current source to the timing capacitor for said short period of time immediately after said timing capacitor is uncoupled from the timing current source to compensate for the polarization losses thereof.

Claim 11

The apparatus of claim 8 wherein the voltage across the timing capacitor slowly decrease due to leakage losses and said compensating means includes an impedance means connected in parallel with said compensating capacitor to conduct a small charging current to the timing capacitor to compensate for the leakage losses thereof.

Claim 12

Apparatus for determining the speed of a moving substance, comprising: means for measuring the time elapsed for the substance to travel a fixed distance including means for generating a signal having a magnitude directly proportional to the elapsed time; and means coupled to said time measuring means for generating a speed signal representing the inverse of the elapsed time, said signal being linearly related to the speed of the substance and convertible into a speed indication, said speed signal generating means including means for generating a pulsating signal having a duty cycle directly proportional to the magnitude of said elapsed time signal.

Claim 13

Apparatus for determining the speed of a moving substance, comprising: means for measuring the time elapsed for the substance to travel a fixed distance including means for generating a signal having a magnitude directly proportional to the elapsed time; and means coupled to said time measuring means for generating a speed signal representing the inverse of the elapsed time, said signal being linearly related to the speed of the substance and convertible into a speed indication, said speed signal generating means including means for generating a pulsating signal having a duty cycle directly proportional to the magnitude of said elapsed time signal.

Claim 14

The apparatus of claim 10 wherein said pulsating signal generating means includes means for generating a periodic signal at a fixed frequency, the absolute magnitude of said periodic signal having a first value at the beginning of each period and linearly increasing toward a second value during each period, storage means having an output assuming a second state at the beginning of each period and assuming a first state in response to the magnitude of said linearly increasing signal reaching a preselected percentage of the magnitude of said elapsed time signal.

Claim 15

The apparatus of claim 11 wherein said periodic signal generating means includes a differential amplifier having a normal input, an inverting input and an output, said elapsed time signal coupled to said inverting input, said linearly increasing signal coupled to said normal input, said amplifier generating an output signal having a magnitude directly proportional to the arithmetic difference between the magnitude of said elapsed time and linearly increasing signals, said storage means coupled to said amplifier output and assuming said second state in response to said amplifier output assuming a preselected value.

Claim 16

The apparatus of claim 11 wherein said periodic signal generating means includes a capacitor, means for linearly charging the capacitor toward the second value at a uniform rate in response to said output assuming the second state, means for discharging the capacitor to the first value in response to said output assuming said first state.

Claim 17

The apparatus of claim 10 wherein said speed signal generating means includes means for generating a speed signal having an average magnitude inversely proportional to said duty cycle, said speed signal being directly proportional to the speed of the substance.

Claim 18

Apparatus for determining the speed of a moving substance, comprising: means for measuring the time elapsed for the substance to travel a fixed distance including means for generating a timing signal representing the time elapsed for the substance to travel said fixed distance, and means for storing said elapsed time signal for a preselected read period; and means coupled to said time measuring means for generating a speed signal representing the inverse of the elapsed time, said signal being linearly related to the speed of the substance and convertible into a speed indication.

Claim 19

Apparatus for determining the speed of a moving substance, comprising: means for measuring the time elapsed for the substance to travel a fixed distance including means for generating a timing signal representing the time elapsed for the substance to travel said fixed distance, and means for storing said elapsed time signal for a preselected read period; and means coupled to said time measuring means for generating a speed signal representing the inverse of the elapsed time, said signal being linearly related to the speed of the substance and convertible into a speed indication.

Claim 20

The apparatus of claim 15 wherein the timing signal generating means must be reset prior to each elapsed time measurement and said elapsed time measuring means includes means for automatically resetting said timing signal generating means at the end of said read period.

Claim 21

The apparatus of claim 15 wherein the storage means must be reset to an initial condition wherein no signal is stored and said time measuring means includes means for resetting said storage means at the end of the read period.

Claim 22

The apparatus of claim 15 wherein said time measuring means includes means for giving a read indication throughout said read period.

Claim 23

Apparatus for determining the speed of a moving substance, comprising: means for measuring the time elapsed for the substance to travel a fixed distance including means for indicating that an elapsed time measurement is being made; and means coupled to said time measuring means for generating a speed signal representing the inverse of the elapsed time, said signal being linearly related to the speed of the substance and convertible into a speed indication.

Claim 24

Apparatus for determining the speed of a moving substance, comprising: means for measuring the time elapsed for the substance to travel a fixed distance including means for indicating that an elapsed time measurement is being made; and means coupled to said time measuring means for generating a speed signal representing the inverse of the elapsed time, said signal being linearly related to the speed of the substance and convertible into a speed indication.

Claim 25

The apparatus of claim 19 wherein said time measuring means includes means for indicating that said elapsed time measuring means is ready to make another measurement in response to both said timing signal generating means and said storage means being reset.