U.S. patent number 3,626,164 [Application Number 04/833,646] was granted by the patent office on 1971-12-07 for digitalized coincidence correction method and circuitry for particle analysis apparatus.
This patent grant is currently assigned to Coulter Electronics, Inc.. Invention is credited to Claude J. Collineau, Jacques A. Pontigny.
United States Patent |
3,626,164 |
Pontigny , et al. |
December 7, 1971 |
DIGITALIZED COINCIDENCE CORRECTION METHOD AND CIRCUITRY FOR
PARTICLE ANALYSIS APPARATUS
Abstract
So as to generate a correct count of particles from apparatus
which progressively loses individual counting pulses primarily due
to the physical coincidence of two particles in the detecting
transducer of the apparatus, the subject method enables digitalized
addends to be progressively added to the augend formed by the
detected count so as to yield, as a continuously forming sum, a
corrected count which closely approximates the true particle count.
The subject circuitry includes a series of decade counters which
receive the detected, augend, pulses and, at progressive count
levels, such as increments of one thousand, enable, and/or trigger
a selected one of a plurality of correction establishing circuits,
to deliver one or more addend related signals to a selected one of
the decade counters. Depending upon the number of such related
signals and the numeric rank of the receiving decade counter, a
predetermined addend is supplied. This trigger and feedback
relationship increases the increments of addend as the detected
count increases.
Inventors: |
Pontigny; Jacques A.
(Montmorency, FR), Collineau; Claude J.
(Epinay/Seine, FR) |
Assignee: |
Coulter Electronics, Inc.
(Hialeah, FL)
|
Family
ID: |
26182068 |
Appl.
No.: |
04/833,646 |
Filed: |
June 16, 1969 |
Foreign Application Priority Data
|
|
|
|
|
Jun 19, 1968 [FR] |
|
|
155649 |
Jun 19, 1968 [FR] |
|
|
155650 |
|
Current U.S.
Class: |
702/100; 377/12;
708/101; 377/50; 702/46 |
Current CPC
Class: |
G01N
15/1227 (20130101) |
Current International
Class: |
G01N
15/10 (20060101); G01N 15/12 (20060101); G06f
015/36 () |
Field of
Search: |
;235/92 (30)/ ;235/92
(31)/ ;235/92 (34)/ ;235/92 (56)/ ;235/150.3,153,151.3 ;324/71CP
;328/34,46,120 ;307/220,226,271 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Morrison; Malcolm A.
Assistant Examiner: Dildine, Jr.; R. Stephen
Claims
We claim:
1. A method for progressively and automatically correcting the
digitalized accumulation of counting data which normally is subject
to random error, comprising the steps of:
receiving in a cumulative and digitalized mode the counting data as
an augend,
detecting in a cumulative and digitalized mode the value of the
augend relative to a succession of addend corrections and instances
of correction, such instances of correction being correlated to a
predetermined set of augend values,
determining the succession of addend corrections for each value in
the set of augend values,
generating the correlated addend at each instance of correction,
and
applying to the augend each addend as it is generated, such that
the augend cumulatively is the sum of the counting data and the
addends.
2. A method according to claim 1 further comprising the step of
relating the amount of addend, for said generating and applying
steps, to the then detected value of the augend.
3. A method according to claim 2 further comprising the step of
enabling said generating of at least some of the addends at a prior
instant related to the detecting of certain augend values.
4. A method according to claim 2 further comprising
repeating said generating at fixed values of the augend which are
digitally spaced primarily equally from one another.
5. A method according to claim 1 further comprising the step of
delaying in a predetermined mode said generating relative to said
detecting for an interval based upon the receipt of a fixed
increment of augend.
6. A method according to claim 1 further comprising
creating by said generating different individual amounts of addend,
depending upon the then received value of the augend.
7. A method according to claim 6 further comprising
producing by said generating, for said applying, at least one
pulsed response, each such pulsed response being a fraction of the
addend thereby applied.
8. A method according to claim 6 further comprising
creating by said generating addends which are multiples of one
another depending upon the value of the augend.
9. A method according to claim 1 further comprising the step of
correlating the addend of each correction individually and
cumulatively with a theoretical statistic correction curve.
10. A method according to claim 1 and accomplishing said receiving
and detecting by
arranging in digital order a plurality of count retaining stages
and
directing said applying, at said instances of correction, to a
particular one of the ordered stages depending upon the amount of
addend and the value of the augend.
11. A method according to claim 10 further comprising the step
of
obtaining from at least some of the ordered stages, as a
representation of the results of the receiving and applying steps,
the corrected count they are retaining.
12. A method according to claim 11 further comprising
interrogating sequentially each of the stages for the count it is
retaining, during said obtaining.
13. A method according to claim 1 further comprising the step
of
initiating the counting data in an analyzer of particles.
14. A method according to claim 13 further comprising the steps
of
moving a fluid suspension of particles for purposes of said
initiating, and
regulating said generating and applying with reference to said
moving.
15. A method according to claim 14 further comprising
sensing individual particles in suspension as they pass with
reference to a scanning zone, for purposes of said initiating,
the random error being caused by the physical coincidence of
particles in the scanning zone.
16. Apparatus for progressively and automatically correcting the
digitalized accumulation of counting data which normally is subject
to random error, comprising:
means for receiving in a cumulative and digitalized mode the
counting data as an augend,
means coupled with said receiving means for detecting in a
cumulative and digitalized mode the value of the augend relative to
a succession of addend corrections and instances of correction,
such instances of correction being correlated to a predetermined
set of augend values,
means for determining the succession of addend corrections for each
value in the set of augend values,
means responsive to at least said determining means for generating
the correlated addend at each instance of correction, and
means for applying to the receiving means each addend as it is
generated, such that the augend cumulatively is the sum of the
counting data and the addends.
17. Apparatus according to claim 16 further comprising
control means coupled to said generating means for relating the
amount of addend next to be generated to the then detected value of
the augend.
18. Apparatus according to claim 17 further comprising
means responsive to at least said receiving means for enabling said
generating means, for at least some of the addends, at a prior
instant related to the detecting of certain augend values.
19. Apparatus according to claim 17 wherein
said detecting and control means, in combination, form means for
triggering said generating means at fixed values of the augend
which are digitally spaced primarily equally from one another.
20. Apparatus according to claim 17 wherein
said detecting and control means are arranged to coact to correlate
the addend of each correction individually and cumulatively with a
theoretical statistic correction curve.
21. Apparatus according to claim 16 further comprising
means interposed between said detecting and generating means for
delaying in a predetermined mode the operation of said generating
means for an interval based upon the receipt by said receiving
means of a fixed increment of augend.
22. Apparatus according to claim 16 wherein
said generating means includes means for defining different
individual amounts of addend, depending upon the then received
value of the augend.
23. Apparatus according to claim 22 wherein
said defining means includes means for applying at least one pulsed
response to the augend value, such that each pulsed response is a
fraction of the addend thereby applied.
24. Apparatus according to claim 22 wherein
said defining means includes means for creating addends which are
multiples of one another depending upon the value of the
augend.
25. Apparatus according to claim 16 wherein
a plurality of digitally ordered count retaining stages comprise
said receiving means and
at said instances of correction, said applying means is selectively
coupled to a particular one of the ordered stages depending upon
the amount of addend and the value of the augend.
26. Apparatus according to claim 25 further comprising
means for obtaining, from at least some of the ordered stages, the
corrected count they are retaining.
27. Apparatus according to claim 26 wherein said obtaining means
includes
means for interrogating sequentially each of the stages for the
count it is retaining.
28. Apparatus according to claim 16 further comprising
means for initiating the counting data in an analyzer of
particles.
29. Apparatus according to claim 28 wherein said initiating means
comprises
means for moving a fluid suspension of particles and
means for regulating said generating and applying means in response
to the amount of suspension moved by said moving means.
30. Apparatus according to claim 29 wherein said initiating means
further comprises
means for sensing individual particles in suspension as they pass
with reference to a scanning zone,
the random error being caused by the physical coincidence of
particles in the scanning zone.
31. Apparatus for automatically and progressively applying a
digitalized statistic correction to a progessive accumulation of
data which is transmitted in the form of a train of data pulses
that is subject to random error due to the mode of transmitting
such data, said error following a statistically preascertainable
course, said apparatus comprising:
a counter having an input for receiving the data pulses and a
plurality of outputs responsive to and designative of different
data pulse count values,
a correction pulse generator having a plurality of inputs connected
to said plurality of outputs and arranged to be selectively
responsive to said outputs for generating correction pulses at
different of said count values,
at least one feedback path coupling said correction pulse generator
to said counter and arranged for progressively applying thereto
correction pulses having a count value and progression occurrence
so as to closely follow the preascertainable course of said error,
so as to offset same.
32. Apparatus according to claim 31 wherein said correction pulse
generator comprises
at least one control circuit having a first group of said plurality
of inputs, and
at least one pulse establishing circuit, coupled to be enabled by
said control circuit, and having a second group of said plurality
of inputs.
33. Apparatus according to claim 32 wherein
each pulse establishing circuit is coupled to supply correction
pulses to said feedback path, and
said feedback path is coupled to said counter such that each
correction pulse is the equivalent to a specific multiplicity of
count pulses, dependent upon the count value.
34. Apparatus according to claim 32 wherein said plurality of
inputs includes
a third group coupled to specific ones of said control circuits and
arranged to enable them at different specific count values.
35. Apparatus according to claim 32 wherein
a plurality of coupled pairs, each having one of said control
circuits and one of said pulse-establishing circuits, is
provided,
each said circuit pair has one of said first and second groups of
inputs, and
each said circuit pair is responsive to a selectively different
range of count values.
36. Apparatus according to claim 35 wherein
circuitry means intercouples said circuit pairs in such manner that
only one pair is capable of responding to the counter outputs at
any one time, and
such capability correlates to the selectively different range of
each said circuit pair.
37. Apparatus according to claim 36 wherein
a first power source, which is arranged to have enough power to
operate only one of said control circuits at any one time, is
intercoupled to said control circuits and comprises said circuitry
means, and
said first group of inputs are selectively connected to the control
circuits to determine their sequence of operation.
38. Apparatus according to claim 32 wherein each said pulse
establishing circuit comprises
a trigger element,
a storage element coupled to said trigger element for periodically
triggering same until said storage element is discharged, and
a conduction disabling circuit connected to the output of said
triggering element for periodically disabling same.
39. Apparatus according to claim 38 wherein
a delay element is interposed between said counter and said second
group of inputs, and
said delay element has an output connected to said storage
element.
40. Apparatus according to claim 38 wherein
the relative parameters of said storage element and said conduction
disabling circuit determine the number of times said triggering
element can be triggered while said storage element is being
discharged, and
each said triggering provides one of said correction pulses to said
feedback path.
41. Apparatus according to claim 40 wherein said counter
comprises
a plurality of serially coupled counting stages each designating a
numeric order, and said apparatus further comprises
pulse synchronized interrogating circuitry connected to at least
the numerically most significant of said stages for obtaining their
count value for readout purposes.
42. Apparatus according to claim 41 in which said data pulses are
each derived from a particle in a fluid suspension, and said
apparatus further comprises
regulating means responsive to the measurement of a predetermined
volume of the fluid suspension, for purposes of particle analysis,
to thereby regulate the duration of the operation of said
correction pulse generator.
Description
BACKGROUND OF THE INVENTION
This invention is directed to a method and counting circuitry which
provide a statistic correction to a detected train of count pulses,
such that effective random loss of the phenomena being counted does
not induce ultimate counting error.
Now well known in the art of electronic particle counting and
analyzing is apparatus marketed under the trademark "Coulter
Counter." Such apparatus and portions thereof are disclosed in
several U.S. Pats., for example, Nos. 2, 656,508; 2,985,830; and
3,259,842. A significantly important portion of such apparatus is
the minute scanning aperture or scanning ambit relative to or
through which pass and are detected single particles at a rate
often well in excess of 1,000 per second. Because of the physical
parameters of the scanning aperture, particles, rate of flow, etc.
there frequently results the coincidence of two particles in the
scanning ambit. As a result, there is effectively scanned and
detected only one particle, not two.
Although such coincidence is random in time, it follows a
statistically ascertainable course from which curves, tables, and
formulas are obtainable. A relatively simple one of such formulas
is:
n'=k(n.sup.2 /1000)
In which
n' = the total number of coincidences, i.e., the required
addend;
k = a constant which relates primarily to the physical parameters
of the scanning elements of the apparatus and the average particle
size; and
n = the detected number of particles, the augend. Accordingly, the
desired or corrected count N will equal the sum of n+n'.
Heretofore, the operator of a "coulter Counter" would obtain the
augend count by analysis of a suspension of particles and then
would refer to a coincidence correction chart which presented the
proper correction or addend for a very large selection of augends.
The sum thereof would then be the corrected count which the
operator would record.
Although the use of charts provides an accurate result, it is both
time-consuming and prohibits the fully automatic recording and
processing of the corrected counts. Also, of course, the
accumulating count during analysis is uncorrected.
The use of analog, nonlinear meters and/or elements in the output
state of a "coulter Counter" has also been accomplished with
limited success; however, in many used a direct reading digitalized
output is greatly to be preferred.
SUMMARY OF THE INVENTION
Accordingly, it is a primary object of this invention to provide
method and circuitry which provide a digitalized, direct reading
corrected output for a counting apparatus that requires a
continuously applied correction factor.
Another object of the invention is to provide automatic,
digitalized coincidence correction circuitry for particle analysis
apparatus.
A further object of the invention is to provide digitalized
coincidence correction circuitry which operates in a feedback mode
to incrementally supply addends to the particle count as it is
being accumulated.
To achieve the above and other objects and overcome the
deficiencies in the prior art, the invention provides method and
circuitry exemplified by a plurality of decade counters serially
coupled to the output of the particle scanner. Certain of the
decade counters provide, at predetermined count levels, enabling
and triggering signals to correction establishing circuits of a
correction pulse generator, which in turn generate one or more
correction pulses that are fed back to at least one of the decade
counters. Because of the interconnection of the circuitry elements,
the incremental corrections progressively cause the sum or
corrected count to follow a true count curve.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a block diagram of a particle analysis apparatus
including the present invention;
FIG. 2 is a diagram of the decade counter and correction pulse
generator portions of the invention;
FIG. 3 is a graph showing a theoretical statistic correction curve
and curves and other indicia related to the method and operation of
the invention;
FIG. 4 is a schematic diagram of the combination of the delay
circuit and one of the correction establishing circuits in a
preferred embodiment of the correction pulse generator of the
invention;
FIG. 5 is a chart showing waveforms related to the schematic in
FIG. 4; and
FIG. 6 is a schematic diagram of a preferred form of the correction
pulse generator of the embodied invention.
DESCRIPTION OF A PREFERRED EMBODIMENT
Although practice of this invention is not limited to its use with
a "Coulter Counter," such will be the described embodiment,
particularly with reference to FIG. 1. Such an apparatus comprises
a detector 1, including a beaker 2 filled with a sample liquid
containing the suspension of particles to be counted. A glass tube
3 of substantially smaller diameter extends into the beaker, is
closed at its lower end, and is connected to a source of vacuum
(not shown) and to a siphon manometer 4. The lower end of the tube
3 has an aperture 5 in its lateral wall. The aperture is of
microscopic size and, for example, is in a sapphire member fixed
permanently in said wall.
The aperture tube 3 and all the other accessories are filled with a
compatible fluid or additional amounts of the sample liquid. Two
electrodes 6 and 7 are provided on each side of the aperture 5 and
are connected to conductors 8 and 9, which constitute the output
terminals of the detector.
The manometer 4 is employed for causing a given amount of the
sample liquid to pass through the aperture. It comprises a column
of mercury 10 and its free end is open to the atmosphere. The
column of mercury is so arranged that, in the course of its
movement, it touches contacts 11 and 12 which serve respectively to
start and stop the counting procedure. For this purpose, the column
of mercury can be grounded.
To operate this detector, the operator opens a cock 13 leading to
the source of vacuum so that the column of mercury moves into an
unbalanced condition as illustrated. After closure of the cock 13,
the column of mercury 10 tends to resume its state of balance and
in doing so draws the sample liquid through the aperture 5. The
column of mercury then comes in contact with the electrode 11 and
an electrical potential is created across the electrodes 6 and 7 to
produce a current in the liquid through the aperture. Now, in
passing through the aperture, the particles in suspension modify
the impedance between the two electrodes 6 and 7, so that said
current is modulated and produces a series of pulses.
The conductors 8 and 9 are connected to a pulse amplifier 14 which,
owing to a shaping circuit therein converts the input series of
pulses into rectangular signals having a fixed width and height.
The output of the amplifier 14 is connected to a decade counter
array 15 comprising two transistor decades 16 and 17, each of which
consists of four flip-flop circuits which are interconnected in the
known manner as to afford a division by 10. The decade 17 is
followed by an amplifier 18 connected to a series of three
thyratron decades 19, 20 and 21.
The amplifier 18 converts the signals which issue from the decade
17, and have a width varying as a function of the mean counting
frequency, into constant width pulses and amplifies them in such
manner as to render them capable of acting on the thyratrons of the
following decades. In a preferred embodiment, each of the latter
comprises a shaping thyraton, a series of 10 counting thyratrons,
and a series of 10 interrogation thyratrons. The counting and
interrogation thyratrons are coupled in pairs through their
cathodic load in such manner as to interrogate the decades, as will
be explained hereinafter.
A control circuit 22 is connected to the electrodes 11 and 12 of
the detector 1 and moreover to a multivibrator 23, which produces
pulses at low frequency for example at 3 Hz. The control circuit
also acts on switches 24, 25 and 26 which bring associated systems
into circuit at appropriate instants. For this purpose, the control
circuit comprises conventional delay circuits which will not be
described in detail.
The output of the multivibrator 23 is connected, through a shaping
circuit 27 and the switch 24, to an interrogation lead 28 connected
to the interrogation thyratrons of the decades 19, 20, and 21. The
multivibrator is also connected to the inputs of a series of three
amplifiers 29, 30 and 31 whose outputs are connected to a printer
32 comprising, for each digit position of the registered number, a
drum or number which is individually movable step-by-step by the
effect of pulses applied to its drive means. Each of the amplifiers
29, 30 and 31 includes a blocking input 33 which is connected to
one of the series of interrogation thyratrons of the considered
decade through conductors 34.
A correction pulse generator 35 is associated with the counter
array 15 and will be described hereinafter in considerable detail
as will other circuit portions illustrated in FIG. 1, but not yet
mentioned.
A source of power 36 is provided which suitably feeds each circuit
of the apparatus through conductors which, in the interest of
greater clarity, have not been shown.
FIG. 2 shows the block details of correction pulse generator 35 and
includes the counter array 15 of which the shaping amplifiers 14
and 18 have been omitted. This circuitry is so arranged as to
introduce a statistic correction in the count effected by the
decades 16, 17, 19, 20 and 21 in such manner that corrected count
is as near as possible to the theoretical count afforded by the
formula given hereinbefore. Accordingly, an automatic correction is
made each time the decade 19 emits a pulse, that is, for each
thousandth pulse counted by the decade counter array. The
correction cycle is divided into four parts having ranges
respectively from 2,000 to 9,999; 10,000 to 39,999; 40,000 to
79,999; and 80,000 to 100,000. In each of these ranges, a different
amount of correction is made. Thus, in the order or the ranges just
mentioned, 20, 100,200 and 400 addend counts are added to the
registered, augend, count each time the decade 19 of the thousands
produces an output pulse. It should be mentioned that no correction
is made below the number 2,000 in respect of the described
example.
The correction pulse generator 35 comprises four correction
circuits each consisting of a correction pulse establishing circuit
and a control circuit, these correction circuits serving
respectively for the corrections of 20,100,200 and 400 per 1,000
pulses counted. For this purpose, a lead 37 takes a signal from the
output 38 of the decade 19 and transmits it to a delay circuit 39.
The output 40 of this delay circuit is connected to four correction
establishing circuits 41 to 44 through input leads 45 to 48. The
pulses issuing from the decade 19 are also applied to the control
circuit 49 through a lead 50 connected to the lead 37. The pulses
issuing from the decade 20 and arriving at a terminal 51 are
simultaneously applied though a lead 52 to the input leads 53 to 55
of control circuits 56 to 58, respectively. Further, a lead 59,
connected to the decade 21, transmits a pulse to a triggering input
of the control circuit 57; whereas, a lead 60, also connected to
the decade 21, transmits a pulse to a triggering input of the
control circuit 58 when the decade counter reaches the numbers
30,000 and 70,000 respectively.
An output from the correction establishing circuit 41 is connected
to an input of the tens decade 17 through a lead 61. This circuit
41 transmits two pulses to this decade 17, i.e. makes a correction
of 20 for each thousandth pulse registered by the decade counter
array.
The outputs from the correction establishing circuits 42 to 44,
respectively send, for each pulse received at their inputs 46 to
48, one, two or four correction pulses to the input of the decade
19 and advances the latter one, two, or four ranks of 100 each
respectively. This is carried out through diodes 62 and a lead 63
and initiating elements to be described in connection with FIG.
4.
The correction pulse generator 35 is started and stopped by a
starting and resetting circuit 64 which receives signals from the
control circuit 22 in FIG. 1 through leads 65 and 66. Finally, the
circuits described hereinbefore are fed from an input terminal 67
connected to the power source 36.
It should be mentioned that the embodiment described preferably
employs as triggering elements cold-cathode thyratrons which have
been found to be particularly suitable for the purpose; however, it
is obvious that these elements can be replaced by other electronic
triggering components, such as for example, vacuum tubes or
semiconductors, providing that the appropriate technological
adaptations are made.
Turning next to FIG. 3, there is shown a graph having a plurality
of different sets of indicia along its exponentially spaced
abscissa and ordinate divisions. Extending upwardly along the
ordinate of the graph is the cumulative value of addend or
correction applied to the decade counter array labeled "Total
Correction." Extending upwardly along the right margin of the graph
are the four previously mentioned ranges which commence at 2,000;
10,000; 40,000; and 80,000 corrected counts then stored in the
decade counter array.
The "Detected Pulses" or augend is marked along the abscissa with
indicia commencing at 700 and terminating past 80,000. Directly
therebelow, on the same scale, but with necessarily earlier points
of intersection of the same count values, is the "Corrected Count"
index.
A theoretical or statistic correction curve 68 is plotted to show
to the progressively required total correction with reference to
the detected or uncorrected number of pulses which would be emitted
from the amplifier 14 in FIG. 1. Thus, at any point on the curve 68
there is a corresponding total amount of required correction and
this data could be tabulated to provide a correction table of the
type earlier mentioned as a form of the prior art in which manual
count correction is possible.
However, in order to render the correcting method and apparatus
automatic, an automatic correction curve 69 is first established in
the form of steps which is as near possible to the statistic
correction curve, taking into account a certain previously imposed
accuracy. The limits of this accuracy are indicated by a pair of
curves marked +1 percent and -1 percent designating their value
limits. Of course, it is possible to be more or less exacting in
the accuracy by providing an automatic curve having a greater or
smaller number of steps and consequently a greater or smaller
complication of the electronic circuits of the apparatus.
Before discussing the schematic details of FIGS. 4-6, the overall
operation of the invention will be discussed from the point in time
that the 1,000th detected pulse has been received by the decade
count array 15. At such time, the decade 19 emits at its output 38
a triggering signal to the control circuit 49, by way of the leads
37 and 50, which enables the correction establishing circuit 41,
but does not elicit therefrom any correction signals. Upon receipt
of the 2,000 detected pulse, the decade 19 again produces a trigger
signal which, by way of the delay circuit 39 and the leads 40 and
45, is coupled to the correction circuit 41 and causes it to
produce two correction pulses. The latter are applied to the input
of the decade 17 through the lead 61. The decade 17 thus advances
two ranks and therefore adds 20 to the registered count, the
indicated total or corrected count then being 2,020 pulses.
Thereafter, each time the decade 19 emits an output signal, the
correction circuit 41 sends two pulses to the decade 17 so as to
add 20 to the registered count. Thus, when the counter indicates
the number 10,000 the detector has delivered only 9,840 pulses.
At the count of 10,000, the decade 20 emits a pulse at the output
51, the control circuit 56 is actuated through the leads 52 and 53
to enable the circuit 42, while the pulse establishing circuit 41
is simultaneously inhibited (by circuit means subsequently to be
discussed). When once again the decade 19 emits a pulse, the pulse
establishing circuit 42 is triggered by way of the delay circuit 39
and the input lead 46 and the circuit sends one pulse to the input
of the decade 19 through the lead 63 so as to advance it one rank
and cause it to make a correction of 100. Each time, the decade 19
thereafter emits a pulse a correction of 100 is made by the pulse
establishing circuit 42.
When the decade 21 attains the number 30,000, it sends a pulse on
the lead 59 to the control circuit 57 so as to enable it. Upon the
arrival of the following output signal, at the terminal 51 of the
decade 20 representing the number 40,000, the control circuit 57 is
triggered by way of the leads 52 and 54 and enables the pulse
establishing circuit 43 and also inhibits the pulse establishing
circuit 42. Upon the arrival of the following pulse at the output
of the decade 19, number 41,000, the pulse establishing circuit 43
sends two correction pulses to the input of the decade 19 so as to
provide an addend of 200. Thereafter, each time the decade 19 emits
a pulse, a correction of 200 is made in the count of the counter
array 15. Thus, when the latter indicates the corrected count of
40,000, only 37,100 pulses have been delivered by the detector
1.
When the decade 21 attains the corrected count of 70,000, a pulse
is sent to the control circuit 58 so as to enable it through the
lead 60. Thereafter, as soon as the decade 20 emits the following
output pulse, number 80,000 on the leads 52 and 55, the control
circuit 58 enables the pulse establishing circuit 44 and inhibits
the pulse establishing circuit 43. The following pulse emitted by
the decade 19, number 81,000, produces four pulses at the output of
the pulse-establishing circuit 44, these pulses being sent to the
decade 19 and providing an addend of 400. This is thereafter
repeated until the counter array 15 is completely full.
It will be observed that the counting could very well stop before
the counter 15 is full, the number finally registered depending on
the number of particles contained in the measured volume of the
sample liquid. Moreover, the counting is stopped by the column of
mercury 10 when it touches the contact 12. At that time, the given
volume of the liquid sample has passed through the measuring
aperture 5. The stopping of the counting by means of the column of
mercury 10 also triggers the multivibrator 23 through the control
circuit 22, and the latter closes the switches 24 to 26 at the
appropriate moments.
The multivibrator 23 transmits the interrogation pulses to the
shaping circuit 27 and these pulses are thenceforth applied to the
interrogation thyratrons of the decades 19 to 21 so as to
interrogate them. At the same time, the multivibrator 23 transmits
pulses to the amplifiers 29 to 31 which are connected to the
printer mechanisms corresponding to the hundreds, thousands and ten
thousands through the switches 26.
The interrogation pulses have two particular purposes. They cause
the drums of the registering mechanisms of the printer to advance
simultaneously step by step, and they interrogate the interrogation
thyratrons of the decades 19 to 21. As soon as, in the
interrogation series of the decade concerned, the interrogation
thyratron corresponding to the energized counting thyratron is
reached, a blocking pulse is sent to the corresponding amplifier
through the lead 34 so that the amplifier is blocked. The drum of
the printer 32 then stops at the number represented by the
interrogation thyratron that was energized.
In order to further facilitate an understanding of the invention
and its operation, a preferred embodiment of one of the correction
pulse establishing circuits will be described with reference to
FIG. 4, this circuit being similar to each of the circuits 41-44
and associated with a delay circuit similar to the circuit 39.
As shown in FIG. 4, two thyratrons 70 and 71 have their anodes
connected to a +200 v. source, for example, through anode resistors
72 and 73. The cathode of the thyratron 70 is grounded through an
RC circuit comprising a resistor 74 and a capacitor 75. The grid of
the thyratron 70 receives control pulses through a capacitor 76 and
it is polarized by a +100 v. source, for example, through a
resistor 77. The cathode of the thyratron 70 is also connected to a
coupling capacitor 78 which is connected to the grid of the
thyratron 71. This grid is polarized at the voltage of +100 v.
through a resistor 79. The cathode of the thyratron 71 is grounded
through an RC circuit consisting of a resistor 80 and a capacitor
81 and is connected to the output of the circuitry through a diode
82. Note that the RC time constant of the resistor 74 and the
capacitor 75 is much greater than that of the resistor 80 and
capacitor 81.
The operation of this circuitry is as follows with reference to
FIG. 5. An input or count pulse 85 is applied to the capacitor 76
and causes, after a certain inherent delay t, the ionization of the
thyratron 70 which, being conductive, charges the capacitor 75.
This charging continues until the voltage at the terminals of the
capacitor has such value that it lowers the anode-cathode voltage
of the thyratron below the ionization value. The thyratron thus
becomes nonconductive. The time constant of the RC circuit 74 and
75 is so calculated as to produce the conduction curve 86 in which
a threshold voltage 87 defines the conduction range of the
thyratron 70.
The operation of the thyratron 71 is identical to that of the
thyratron 70. Thus, a pulse applied to the grid of the thyratron 71
triggers the latter and charges the capacitor 81 until the voltage
at its terminals reaches such value that the thyratron ceases to
conduct. As mentioned before, the charging time of the capacitor 75
is much longer than that necessary for charging the capacitor 81.
Consequently, during the time which elapses between the thyratron
conduction range of the curve 86, during which the capacitor 78 is
also charged, the latter periodically transmitting a part of its
energy to the grid of the thyratron 71 by way of a pulse train 88,
the thyratron 71 is periodically conductive and periodically
charges the capacitor 81. The number of times that the capacitor 81
can be charged and discharged therefore in particular depends on
the capacity of the capacitor 78.
For a resistor 74 of 560 ohms, a capacitor 75 of 47 microfarads, a
resistor 80 of 1 megohm and a capacitor 81 of 0.22 microfarads, a
value of 1.5 microfarads must be chosen for the capacitor 78 to
obtain one pulse, 2.7 microfarads to obtain two pulses and 5.1
microfarads to obtain four pulses, the latter as in the pulse train
89, per input pulse 85.
In the embodied apparatus, there are employed only the single delay
circuit 39 such as that described hereinbefore, and the four
correction pulse establishing circuits 41-44, each of which
comprises an input capacitor, such as the capacitor 78 having the
appropriate value. A schematic thereof is shown in FIG. 6. Thus,
the output lead 40, which is connected to the junction point of the
capacitors 75 and 78 in FIG. 4 is similarly connected to each of
the correction pulse establishing circuits 41-44 through their
respective capacitors 78 in FIG. 6.
As previously mentioned, each of these pulse establishing circuits
is associated with a respective control circuit 49, and 56-58,
comprising a thyratron 90 which is capable of polarizing, when
rendered conductive, the grid of the thyratron of the associated
pulse establishing circuit. This is effected through the respective
leads 91-94 also shown in FIG. 2. The thyratrons of the control
circuits can be polarized by a polarizing voltage through the lead
52 to the input leads 53-55. Thus, the thyratrons are polarized
only upon the counter array 15 being filled up to 10,000. On the
other hand, the thyratron of the control circuit 49 is polarized as
soon as the operator has started the apparatus and ionized the
thyratron 95 of the circuit 64 by means of the terminal 65.
The thyratrons of the apparatus are arranged in two main groups A
and B as to their anode source. For this purpose, the power source
36 comprises two distinct parts each of which consists of a common
anode resistor 96 for the considered group, this resistor being in
series with a diode 97 between two supply lines 98 and 99 brought
respectively to potentials of +400 and +200 v. The terminals A and
B are at the junctions of the respective resistors and diodes and
are connected to the anode terminals of the thyratrons of the
respective groups, these terminals having the corresponding letter
references in FIG. 6. Owing to this anode coupling of the two
groups of thyratrons, only a single thyratron per group can be
triggered; and the thyratron, which is triggered at a given moment
by means of a voltage applied to its grid, renders nonconductive
the previously conductive thyratron in respect of which the anode
voltage is then too weak to maintain the ionization.
The operation of the circuitry shown in FIG. 6 will now be
described in detail from a starting point at which it will be
assumed that none of the thyratrons of the circuitry is conductive.
Starting up is achieved by the application of a pulse at the
terminal 65 of the start circuit 64, its thyratron 95 being
rendered conductive and the grid thereof being permanently
polarized by a potential of +100 v. The current which is
established in the thyratron 95 supplies a potential by way of a
lead 100 to the grid of the thyratron 90 in the control circuit 49
so as to polarize it. The pulse establishing circuit 41 is then
enabled to receive the thousandth pulse recorded by the
counter.
At the moment the decade 19 counts the thousandth pulse, it
transmits a pulse to the delay circuit 39 through the lead 37 and
as the thyratron 70 is permanently polarized by a potential of +100
v. on its grid, it is rendered conductive. At the same time, the
thyratron in the control circuit 49, previously polarized through
the lead 100, is rendered conductive by way of the lead 50 and thus
polarizes the thyratron 71 in the correction circuit 41 through the
concerned lead 91.
Upon the arrival of pulse 2,000 in the counter, the decade 19
transmits a new pulse to the delay circuit 39 so that the thyratron
70 previously rendered nonconductive by its cathode capacitor 75,
is rendered once more conductive, and owing to the polarization of
the thyratron 71 and to the value of the capacitor 78, the latter
will produce two pulses which are transmitted by the output lead 61
of the correction circuit 41 to the tens decade 17 so as to cause
it to advance two ranks.
An addend value of 20 is thus added to the uncorrected count value
of 2,000 and the counter jumps to the number 2020 as shown in the
lower left corner of FIG. 3. This correction is thenceforth made
each time the decade 19 produces an output pulse corresponding to
the number 1,000, so that at the arrival of the pulse 9,840 at the
input 101 of the counter 15, the latter displays in fact the
coincidence corrected number 10,000.
As soon as the pulse corresponding to the number 10,000 issues from
the decade 20, the thyratron in the control circuit 56 is rendered
conductive through the leads 52 and 53. Simultaneously, the
corresponding thyratron in the control circuit 49 is turned off
owing to the common anode coupling to point A in the power source
36 as earlier explained; this operation thenceforth preventing the
conduction of the thyratron in the correction circuit 41 whose
polarization is eliminated. On the other hand, the grid of the
thyratron in the correction circuit 42 is polarized through the
associated lead 92. As soon as the decade 19 once more records the
arrival of 1,000 pulses; that is, when the counter displays 11,000,
it transmits the signal to the grid of the thyratron 70 in the
delay circuit which renders it conductive. Then, owing to the value
of the capacitor 78 in the circuit 42, only one pulse is produced
by the thyratron 71 therein, this pulse being transmitted to the
input of the decade 19 through the concerned diode 62 and the lead
63. As the decade 19 advances one rank, a correction value of 100
is added to the number displayed by the counter 15, which
consequently displays the number 11,100. At this moment, the
detector has transmitted to the counter only 10,840 pulses. This
correction of 100 appears on FIG. 3 with associated reference 102
and returns the automatic correction curve 69 from -1 percent error
to very close to the theoretical correction curve 68. This
correction is repeated thereafter each time the decade 19 emits an
output signal until the counter displays the number 40,000.
However, at the number 30,000, the decade 21 transmits a pulse
through the lead 59 which thus polarizes the thyratron in the
control circuit 57. As soon as the counter displays the number
40,000, the decade 20 renders the same thyratron conductive through
the leads 52 and 54. At this moment, the counter has received at
its input terminal 101 only 36,940 pulses. Owing to the common
anode coupling, the thyratron in the control circuit 56 is turned
off and simultaneously eliminates the polarization of the grid of
the thyratron 71 in the associated correction circuit 42. The
latter can no longer produce correction pulses. On the other hand,
the thyratron in the control circuit 57 polarizes the grid of the
thyratron in the correction circuit 43 which, upon the arrival of
the following pulse at the output of the decade 19 which is, at
number 41,000, becomes conductive twice, effecting the correction
value of 200, two pulses being applied to the input of the decade
19. This correction of 200 is made every thousand pulses until the
counter 15 displays the number 80,000. However, at that moment, the
counter has received only 68,300 input pulses. Because of the
correction beginning at 40,000, the automatic correction curve 69
again swings away from the -1 percent curve toward the +1 percent
curve; however, nearing the count of 80,000, the -1 percent curve
is again being approached.
The arrival of the pulse 70,000 polarizes the thyratron in the
control circuit 58 through the lead 60 so that when the decade 20
emits a pulse when it is once more filled by the following 10,000
pulses, that thyratron is turned on and the thyratron in the prior
control circuit 57 is turned off, which renders the thyratron in
the correction circuit 43 inoperative. On the other hand, the
thyratron in the correction circuit 44 then is able to produce
pulses. Consequently, upon the arrival of the pulse 81,000, the
decade 19 excites the thyratron 70 in the delay circuit 39 so as to
produce four pulses in the correction circuit 44 owing to the value
of the capacitor 78. These pulses are applied to the decade 19
through the considered diode 62 and the lead 63. The decade 19 then
advances four ranks so as to make a correction of 400. The display
of the counter 15 is thereafter corrected in this way every
thousand pulses until the total filling of the counter. If the
apparatus is not wholly stopped by elimination of the source
voltages on the lines 98 and 99, the thyratron in the circuit 58
remains energized until the arrival of the following starting pulse
at the terminal 65. The latter, in rendering the thyratron 95
conductive, turns off any one of the thyratrons 90 which was the
last to remain energized.
It should be mentioned that the system described hereinabove
represents one of many possible embodiments of the correction pulse
generator 35. Further, the numerical values of the components and
the numerical examples illustrating the operation of the apparatus
have been given merely for purposes of explanation. The same is
true in respect of the correction curves shown in FIG. 3, since
they depend both upon the uncorrected error produced by the
detecting apparatus and the degree of accuracy desired.
What is desired to be protected by United States Letters Patent
is:
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