Current normalizer for particle size analysis apparatus

Claim 2

Apparatus for normalizing the current delivered to a particle sensing zone which has a variable resistance characteristic and which has a current generating device coupled thereto, said apparatus comprising: a voltage source operable to provide a precise voltage; current generator means connected to said sensing zone and to said voltage source and operable to provide particle sensing current in accordance with the voltage supplied thereto; voltage pulse generator means connected to said current generator means and operable to superimpose voltage pulses on the voltage supplied to said current generator means to effect the provision of simulated particle current pulses at said sensing zone; and adjusting means for adjusting the particle sensing current and the simulated particle current pulses simultaneously.

Claim 3

Apparatus according to claim 1, wherein said voltage pulse generator means includes means connected to said voltage source to receive a supply potential therefrom and operable to generate said voltage pulses in accordance with the value of supply potential received, and wherein said adjusting means includes means for simultaneously varying the voltage potentials supplied to said voltage pulse generator means and said current generator means.

Claim 4

Apparatus according to claim 1, wherein said voltage pulse generator means includes an oscillator for producing pulses and a pulse shaper for shaping the pulses of the oscillator to a Gaussian shape.

Claim 5

Apparatus according to claim 1, wherein said current generator means includes an input amplifier having first and second inputs, said first input connected to said voltage pulse generator means, an output amplifier coupled between said input amplifier and said sensing zone, and a stability feedback circuit connected between said output amplifier and said second input of said input amplifier.

Claim 6

Apparatus according to claim 1, wherein said adjusting means includes first means in said voltage source for providing amplitude doublings of voltage ranges to said current generator means and to said voltage pulse generator means and second means for varying the potential within the doublings.

Claim 7

Apparatus according to claim 1, comprising means for turning said voltage source on and off.

Claim 8

Apparatus according to claim 1, comprising means operable to shunt said voltage source and render said apparatus operable in response to said voltage pulses only.

Claim 9

In particle size analysis apparatus of the type which has a source of direct current connected to a particle sensing zone having a variable resistance characteristic and operable to modulate the direct current and generate a pulse in response to a particle traversing the sensing zone, a pulse sensing amplifier preceded by a filter connected to the source of direct current, means connected to the amplifier for indicating the size of the particle pulses, start-stop means including start and stop contacts operable to initiate and terminate operation of the particle analysis apparatus, the improvement therein comprising: said source of direct current including an adjustable voltage source operable to provide selected potentials and a direct current generator connected to said voltage source and operable to provide direct current in accordance with a selected potential; and a voltage pulse source connected between said adjustable voltage source and said direct current generator for controlling said direct current generator to simulate particle pulses in accordance with a selected potential.

Claim 10

In particle size analysis apparatus of the type which has a source of direct current connected to a particle sensing zone having a variable resistance characteristic and operable to modulate the direct current and generate a pulse in response to a particle traversing the sensing zone, a pulse sensing amplifier preceded by a filter connected to the source of direct current, means connected to the amplifier for indicating the size of the particle pulses, start-stop means including start and stop contacts operable to initiate and terminate operation of the particle analysis apparatus, the improvement therein comprising: said source of direct current including an adjustable voltage source operable to provide selected potentials and a direct current generator connected to said voltage source and operable to provide direct current in accordance with a selected potential; and a voltage pulse source connected between said adjustable voltage source and said direct current generator for controlling said direct current generator to simulate particle pulses in accordance with a selected potential.

Claim 11

Particle size analysis apparatus, comprising: a particle sensing zone for receiving a flow of particles and having a variable resistance characteristic, said zone including an orifice tube and an electrolyte immersing said tube and for suspending particles therein; a source of direct current connected to said particle sensing zone, the direct current being modulated by particles traversing the orifice of said tube to generate particle pulses, said source of direct current including an adjustable voltage source operable to provide selected potentials and a current generator operable to provide a direct current in accordance with a selected potential; display means connected to said sensing zone for indicating the magnitude of particle pulses; particle pulse simulator means connected to said current generator and effective to cause said current generator to produce simulated particle pulses; and means for adjusting the output of said current generator to normalize the current delivered to said sensing zone and compensate its variable resistance.

Claim 12

Particle size analysis apparatus, comprising: a particle sensing zone for receiving a flow of particles and having a variable resistance characteristic, said zone including an orifice tube and an electrolyte immersing said tube and for suspending particles therein; a source of direct current connected to said particle sensing zone, the direct current being modulated by particles traversing the orifice of said tube to generate particle pulses, said source of direct current including an adjustable voltage source operable to provide selected potentials and a current generator operable to provide a direct current in accordance with a selected potential; display means connected to said sensing zone for indicating the magnitude of particle pulses; particle pulse simulator means connected to said current generator and effective to cause said current generator to produce simulated particle pulses; and means for adjusting the output of said current generator to normalize the current delivered to said sensing zone and compensate its variable resistance.

Claim 13

In particle size analysis apparatus of the type wherein at a sensing zone particles are suspended in an electrolyte and caused to flow through an orifice of a tube immersed in the electrolyte, a source of direct current has terminals in the electrolyte on each side of the orifice, and means are connected to the terminals for sensing modulations of the direct current as particle pulses in response to particles traversing the orifice and displaying particle size information in accordance with the size of the particle pulses, the improvement therein comprising: means connected to said source of direct current and operable to cause said source to provide simulated particle pulses at its terminals; and adjustable means for normalizing the output of said source of direct current to compensate for resistance variations effected by the orifice, the electrolyte and the counter emf contact potentials of the terminals.

Claim 14

In particle size analysis apparatus of the type wherein at a sensing zone particles are suspended in an electrolyte and caused to flow through an orifice of a tube immersed in the electrolyte, a source of direct current has terminals in the electrolyte on each side of the orifice, and means are connected to the terminals for sensing modulations of the direct current as particle pulses in response to particles traversing the orifice and displaying particle size information in accordance with the size of the particle pulses, the improvement therein comprising: means connected to said source of direct current and operable to cause said source to provide simulated particle pulses at its terminals; and adjustable means for normalizing the output of said source of direct current to compensate for resistance variations effected by the orifice, the electrolyte and the counter emf contact potentials of the terminals.