US3453438A - Particle counter with liquid responsive start and stop means - Google Patents

Description

July 1, 1969 T: BAN 'ET AL 3,453,438

PARTICLE COUNTER WITH LIQUlL) RESPONSIVLJ START AND STOP MEANS Filed May 9, 1966 COUNTEQ CONTROL.

/ N VE N TORS United States Patent Claims Us. Cl. 250-218 5 Claims ABSTRACT OF THE DISCLOSURE A particle counter for counting suspended particles, ,especially blood cells, in which a determined volume of the liquid to be measured is sucked through a check gate during 'a measuring period and a counting circuit comprising two electrodes is provided on both sides of the gate. The liquid containing the particles to be counted starts and stops the counting process. A closed gas space is provided above the check space. A pressure-alternating device, e.g. an incandescent filament connected over a switch to an electrical supply source, 'or a piston, a diaphragm, a Sylphon membrane or the like, is connected to said closed gas space for providing first a gas pressure for drivingthe liquid out of the check space, and subsequently creating a suction, sucking in the liquid and performing the counting of the suspended particles.

The invention relates to a particle counter for counting suspended particles, especially blood cells.

There are already particle counters comprising a tube with check gate, dipped into a suspension tank, a counting space, two electrodes arranged outside and inside the check gate, inserted in the counting circuit and fitted with counting starter and arrester unit. The counters of this type, which operate with a check gate by reason of conductivity, have to fulfill in general the following duties:

(at) The liquid to be measured is to be sucked through the check gate during the measuring period;

(b) Counting of particles in determined volume must be provided, for which purpose, in general, the starting and arresting of the particle counter unit will be necessary;

(0) Removal of the return liquid is to be provided for.

However manufacturing difiiculties are responsible for the fact that this kind of appliance has not yet appeared on the market.

It is the main object of the invention to provide a particle counter in which the above difiiculties and disadvantages will be eliminated, with a simple design and no manufacturing difiiculties.

The main aim of the invention is to eliminate from the instrument the element causing the greatest problem and defect, i.e. the piston for drawing in of the liquid to be checked, be it a mercury piston or a piston controlled mechanically from outside.

The disadvantages are entirely suppressed by the arrangement according to the invention, which provides a number of advantages. Due to the omission of the mercury, the accompanying inconveniences do not come about. The check liquid is exchanged check by check; the constant liquid change will flush and cleanse the vessel and the check space in its interior, the check liquid does not sully the check space and no deposit takes place. No flow off, no evaporation of the check liquid is possible; therefore no crystallization of the liquid can be observed. In view of its advantageous embodiments no packing problems will arise; even in piston arrangementswhich are believed to be the least advantageous-the requirements for the piston are extremely moderate, because the material seepage, due to defective packing of the piston, does not alter measurement. For volume, it is the displacement of the liquid surface that will be indicated. The instrument can be realized without any moving parts. Special advantage of the instrument according to the invention is the fact that manufacture is simple and easy. It is extremely well adapted to be portable.

In the particle counter according to the invention, com prising a tube, a check space dipped into a suspension tank and fitted with a check gate, as well as two electrodes arranged outside and inside the check gate, inserted in the counting circuit, and having counting start and stop elements, these advantages are achieved by the fact that it comprises a gas space, communicating from above with the check space, limited by the actuating plane of the starting and arresting elements said gas space being separated from the surroundings, which gas space is fitted with a gas pressure regulator, a flap valve, opening on the surroundings, being connected with the side-joining to the tube fitted with the check gateof the check space opposite to the gas space.

Further details of the parictle counter according to the invention are described in the drawing representing an embodiment by way of example.

FIG. 1 shows an arrangement fitted with an incandescent filament containing pressure regulator and shows an arrangement of installed starter and arrester electrodes, and

FIG. 2 represents details of a Sylphon diaphragm arrangement, fitted with external photoelectric indication.

As can be seen on FIG. 1, a tube 4 fitted with a one- Way check gate 3, which preferably fits by means of customary ground glass filling 5 to a counter body 6, reaches down into a receptacle 2 containing a suspension 1. In the body 6, there is formed a check space 9, limited by horizontal planes located by the ends of the electrodes 7 and 8, the volume of which space 9 is known. A gas space 10, in which an incandescent filament 11 is installed, adjoins from above to the check space 9. This is preferably fixed in a cover 12 made of insulating material which supports also the electrodes 7 and 8. The cover 12 seals airtight the gas space 10 and its clamping is provided by hold-downs not represented on the drawing. Upstream from and downstream from the check gate 3 electrodes 13 and 14 are arranged in the known manner. At the extremity of a pipe 15 of the body 6 there is a flap valve 16, closed by a valve rubber similar to that applied for instance in bicycles. Under the outlet of the flap valve 16 preferably a vessel 17 is placed for receiving the removed liquid. The electrodes 13 and 14 are inserted in the particle counting circuit, and the electrodes 7 and 8 in the control circuit of starting and arresting the counting circuit. The incandescent filament 11 is connected through a not represented switch with a current source that will make the incandescent filament glow after the switch is closed.

The operation of the device is easy to understand. For starting the apparatus will be filled up, preferably from belowby applying a funnelled pipe for instance, instead of the pipe 4, with a liquid, perhaps with part of the liquid to be checked, up to a certain level, for instance up to the line 18. The only requirement for the liquid is to possess sufiicient conductivity to operate the counting starter and arrester circuit. Also the pipe 4 is filled up, then placed back. The receptacle 2 containing the suspension 1 to be checked is put around the pipe 4, and then the incandescent filament 11, being switched on to the current source, will be caused to glow to a proper extent. Under the influence of heat the air enclosed in the gas space will expand and press the liquid below the level, the excess liquid will flow out through the pipe 1 and the flap valve 16. Measurement can then be repeated constantly, i.e. can be continued.

In the variant illustrated on FIG. 2 a Sylphon diaphragm 19 is installed in the gas space 10, with the installation represented schematically. The liquid level is lowered below the lower level-of the check space 9 by pressing this diaphragm by means of a push button 20. Indicating is here etfected by means of light- sensitive cells 23 and 24 cooperating with the light sources 21 and 22, the plane of which constitutes limitation for the upper and lower planes of the check space 9. In this case the electrode 14 plays no part in starting and arresting the counting, it takes part only in particle counting. The working of the instrument corresponds to what has been described in connection with FIG. 1, in every respect.

As can be seen, in the instrument according to the invention the piston could be eliminated entirely, as the depression following the lowering of the liquid level exerts intake action on the liquid to be checked; it is this intake action that will suck the liquid through the check gate and makes possible particle counting in the usual way.

We claim:

1. A particle counter comprising a tube having a check gate, a suspension tank in which said check gate is immersed, two electrodes disposed one downstream from and one upstream from the check gate, a counter in electric circuit with said electrodes, means responsive to the presence of liquid in the tube at a first level for starting said counter, means responsive to the presence of liquid in said tube at a second level above said first level for stopping said counter, and means for increasing the pressure in the tubeto drive liquid in the tube below-said first level.

2. A particle counter as claimed in claim 1, said liquid level responsive means comprising two electrodes thlower ends of which terminate at said levels. 1

3. A particle counter as claimed in claim 1,' said liquid level responsive means comprising light sources and photosensitive cells disposed at said first and second levels.

. 4. A particle counter as claimed in claim 1, and a pipe connected to said tube and extending laterally therefrom, and a valve closing the end of said pipe but opening under said increased pressure to discharge from the pipe liquid forced below said first level by said pressure-increasing means. I

5. A particle counter as claimed in claim 1, communicating downwardly from said liquid level responsive means to said check gate.

References Cited UNITED STATES PATENTS y,

Carrick 250-218X 2,555,674 6/1951 2,599,975 6/1952 Carpenter 250 218 X 2,684,008 7/1954 Vonnegut 88---14 2,844,066 7/1958 Friel 88'I14 3,345,502 10/1967 Berg et a1 23592 WALTER STOL'WEIN, Primary Examiner. N

US. Cl. X.R.

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