Particle pulse analyzing apparatus employing linear amplification and logarithmic conversion

Claim 2

Apparatus for providing continuous logarithmic representations of particle size data for analysis of particulate materials, comprising: a sensing zone; means for sensing a stream of fluid containing suspended particles moving through said sensing zone and operable to generate random amplitude, random width, random time-spaced and noise garbled particle pulses in response to respective particles traversing said zone, the amplitudes of said particle pulses representing the size of the respective particles over a wide dynamic range of particle sizes; means connected to said sensing means for receiving the particle pulses; and a logarithmic converter connected to said receiving means and operable in response to the particle pulses to provide output signals which are logarithmically related to the amplitudes of the particle pulses.

Claim 3

Apparatus for providing continuous logarithmic representations of particle size data for analysis of particulate materials, comprising: a sensing zone; means for sensing a stream of fluid containing suspended particles moving through said sensing zone and operable to generate random amplitude, random width, random time-spaced and noise garbled particle pulses in response to respective particles traversing said zone, the amplitudes of said particle pulses representing the size of the respective particles over a wide dynamic range of particle sizes; means connected to said sensing means for receiving the particle pulses; and a logarithmic converter connected to said receiving means and operable in response to the particle pulses to provide output signals which are logarithmically related to the amplitudes of the particle pulses, said logarithmic converter including first and second operational amplifiers each having first and second inputs and an output, said first inputs connected to a reference potential, said second input of said first operational amplifier connected to said receiving means, said second input of said second operational amplifier connected to a reference current source, a nonlinear impedance network, a first nonlinear feedback network including said nonlinear impedance network connected between said output and said second input of said second operational amplifier, and a second feedback network including said nonlinear impedance network and said first operational amplifier connected between said output and said second input of said first operational amplifier.

Claim 4

Apparatus for providing continuous logarithmic representations of particle size data for analysis of particulate materials, comprising: a sensing zone; means for sensing a stream of fluid containing suspended particles moving through said sensing zone and operable to generate random amplitude, random width, random time-spaced and noise garbled particle pulses in response to respective particles traversing said zone, the amplitudes of said particle pulses representing the size of the respective particles over a wide dynamic range of particle sizes; means connected to said sensing means for receiving the particle pulses; and a logarithmic converter connected to said receiving means and operable in response to the particle pulses to provide output signals which are logarithmically related to the amplitudes of the particle pulses, said logarithmic converter including first and second operational amplifiers each having first and second inputs and an output, said first inputs connected to a reference potential, said second input of said first operational amplifier connected to said receiving means, said second input of said second operational amplifier connected to a reference current source, a nonlinear impedance network, a first nonlinear feedback network including said nonlinear impedance network connected between said output and said second input of said second operational amplifier, and a second feedback network including said nonlinear impedance network and said first operational amplifier connected between said output and said second input of said first operational amplifier.

Claim 5

Apparatus according to claim 2, comprising gain limiting means connected to said second input of said first operational amplifier to prevent a sharp increase in the gain thereoF at input signal levels less than a predetermined input level.

Claim 6

Apparatus according to claim 3, wherein said gain means includes a diode connected to said second input and biasing means for said diode effective to maintain said second input above said predetermined input level.

Claim 7

Apparatus according to claim 2, wherein said logarithmic converter further comprises a third amplifier having an input and an output, a coupling capacitor connected between said output of said first operational amplifier and said input of said third amplifier, and a resistor connected between said capacitor and ground as a discharge path for said capacitor during intersignal intervals.

Claim 8

Apparatus according to claim 2, wherein said receiving means comprises a linear amplifier which includes a first amplifier circuit, a second amplifier circuit, a coupling capacitor connected between said first and second amplifier circuits and responsive to the operation of said first amplifier circuit to couple a pulse of one polarity followed by an overshoot signal of the opposite polarity, and gain clamping means in said second amplifier circuit for controlling operation thereof at unity gain in response to said overshoot signal.

Claim 9

Apparatus according to claim 6, wherein said gain clamping means includes a diode connected between the output and the input of said second amplifier circuit, and means for biasing said diode to a predetermined potential.

Claim 10

Apparatus according to claim 7, wherein said second amplifier circuit further comprises a diode serially connected to its output and poled to pass only the pulses of said one polarity.

Claim 11

Apparatus according to claim 6, wherein a first resistor is serially interposed with said coupling capacitor between said first and second amplifier circuits, and said second amplifier circuit comprises a feedback circuit including a plurality of second resistors and means for selectively connecting said second resistors in said feedback circuit to selectively establish resistance relationships with said first resistor to define the selectable gains of said second amplifier circuit.

Claim 12

Apparatus according to claim 9, comprising a resistor connected between said coupling capacitor and ground as a discharge path for said capacitor during intersignal intervals.