US3867613A
Expired / Lapsed
US
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Particle counting apparatus
Assignee: 3M Co
•
Filing: 1972-11-01
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Granted: 1975-02-18
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Expires: 1992-11-01
Abstract
Abstract A particle detection apparatus for determining the number and size of particles present in a plurality of particles dispersed over a field uses an oscillating mirror and movement of the field transversely to the mirror movement to optically scan the field with a succession of scan cycles. Particle indicating signals are produced each time a particle scanned satisfies intensity and size thresholds. Only one particle indicating signal for a particle is used to produce a count signal. Particle indicating signals developed by scans other than the scan from which a count signal for the particle is developed are suppressed. This is accomplished by circuitry including a coincidence circuit and a memory provided by a shift register circuit controlled by a selected number of clock pulses provided for each scan cycle. A feedback circuit is connected to respond to the initiation of a particle indicating signal to assure continuation of the particle indicating signal for the remainder of the time such scan intercepts the particle. The feedback circuit is also connected to respond to the output of the shift register circuit to improve the operation of the circuitry providing for suppressing the signals developed by scans of a particle in excess of the one needed for a count signal. A meter reading is provided which is indicative of the number of particles intercepted when scanning with the field in a selected position to enable the operator to set the intensity threshold correctly.
Inventors
- 👤 David J Schoon
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 22:17
CPC Classifications
G; G06; G06M; G06M11/00
Claims Analysis
Total Claims: 32
Claim 1
Independent Claim
335 words
Particle detection apparatus for determining the number of those particles having a predetermined size that are present in a plurality of particles dispersed over a field comprising: scanning means for scanning said field using a succession of scan cycles, each of said scan cycles moving across said field for successive scanning of each particle presented to the scan cycle, said scanning means providing a particle indicating signal each time a particle having a predetermined size is scanned and supplying a synchronizing pulse at the beginning of each scan cycle; a clock pulse generator connected to said scanning means for receiving said synchronizing pulse and supplying a selected number of clock pulses in response to said synchronizing pulse and at a rate causing the last of said clock pulses to occur prior to completion of a scan cycle; a scan cycle memory including a shift register havinG a clock input, a data input and an output, said shift register requiring said selected number of clock pulses for a cycle of operation, said clock input connected to receive said clock pulses, said data input connected to serially receive each of said particle indicating signals developed by said scanning means, said shift register entering a particle indicating signal when present at said data input while one of said clock pulses is present at said clock input and shifting said entered particle indicating signal to said output upon subsequent receipt by said clock input of clock pulses equal to said selected number; and a signal coincidence circuit for presenting a count signal in response to a first signal unless a second signal is received by said signal coincidence circuit during said first signal, said signal coincidence circuit connected to said scanning means to receive said particle indicating signals from said scanning means as one of said first and second signals and connected to said output of said shift register to receive said particle indicating signals from said shift register output as the other of said first and second signals.
Claim 2
Dependent Claim
335 words
Particle detection apparatus for determining the number of those particles having a predetermined size that are present in a plurality of particles dispersed over a field comprising: scanning means for scanning said field using a succession of scan cycles, each of said scan cycles moving across said field for successive scanning of each particle presented to the scan cycle, said scanning means providing a particle indicating signal each time a particle having a predetermined size is scanned and supplying a synchronizing pulse at the beginning of each scan cycle; a clock pulse generator connected to said scanning means for receiving said synchronizing pulse and supplying a selected number of clock pulses in response to said synchronizing pulse and at a rate causing the last of said clock pulses to occur prior to completion of a scan cycle; a scan cycle memory including a shift register havinG a clock input, a data input and an output, said shift register requiring said selected number of clock pulses for a cycle of operation, said clock input connected to receive said clock pulses, said data input connected to serially receive each of said particle indicating signals developed by said scanning means, said shift register entering a particle indicating signal when present at said data input while one of said clock pulses is present at said clock input and shifting said entered particle indicating signal to said output upon subsequent receipt by said clock input of clock pulses equal to said selected number; and a signal coincidence circuit for presenting a count signal in response to a first signal unless a second signal is received by said signal coincidence circuit during said first signal, said signal coincidence circuit connected to said scanning means to receive said particle indicating signals from said scanning means as one of said first and second signals and connected to said output of said shift register to receive said particle indicating signals from said shift register output as the other of said first and second signals.
Claim 3
Dependent Claim
35 words
A particle detection apparatus in accordance with claim 1 wherein said one of said first and second signals is said first signal and said other of said first and second signals is said second signal.
Claim 4
Dependent Claim
35 words
A particle detection apparatus in accordance with claim 1 wherein said one of said first and second signals is said second signal and said other of said first and second signals is said first signal.
Claim 5
Dependent Claim
62 words
A particle detection apparatus in accordance with claim 1 wherein said scan cycle includes a scan in one direction across the field and a scan in the opposite direction across the field with the last one of said selected number of clock pulses for a scan cycle produced prior to the start of said scan in said opposite direction across the field.
Claim 6
Dependent Claim
92 words
A particle detection apparatus in accordance with claim 1 wherein said scan cycle includes a scan in one direction across the field and a scan in the opposite direction across the field with the last one of said selected number of clock pulses for a scan cycle produced shortly before completion of said scan in said opposite direction across the field, said apparatus further including a divider circuit connected to said signal coincidence circuit for providing one count signal for every two of said count signals produced by said signal coincidence circuit.
Claim 7
Dependent Claim
29 words
A particle detection apparatus in accordance with claim 1 wherein the frequency of said scan cycles relative to the rate at which said clock pulses are produced is adjustable.
Claim 8
Dependent Claim
71 words
A particle detection apparatus in accordance with claim 1 wherein said clock pulse generator includes means for adjusting the rate at which said clock pulses are produced to establish the frequency of the scan cycles relative to the rate said clock pulses are produced for determining the point in a scan cycle when the last one of said selected number of clock pulses following receipt of a synchronizing pulse is provided.
Claim 9
Dependent Claim
143 words
A particle detection apparatus in accordance with claim 1 wherein said scanning means includes a light responsive device; a source of light; means establishing an optical path between said light responsive device and said light source with the field positioned in said optical path including an oscillating mirror disposed between said field and the light responsive device for scanning back and forth across the field in one direction; a mirror control circuit having means operatively coupled to said mirror to sense the position of said mirror and drive said mirror for oscillation at a selected frequency and means for moving the field transversely to the movement of said mirror whereby a sinusoidal optical scan of the field is presented to said light responsive device when the mirror is oscillating in said one direction while said field is moved transverse to said one direction.
Claim 10
Dependent Claim
45 words
A particle detection apparatus in accordance with claim 8 wherein said mirror control circuit includes a pulse forming circuit connected to said clock pulse generator for providing a pulse at the beginning of each scan cycle as the synchronizing pulse for said clock pulse generator.
Claim 11
Dependent Claim
75 words
A particle detection apparatus according to claim 1 wherein said scanning means includes circuitry for establishing the minimum light intensity that a particle must present when scanned before said particle indicating signal can be produced; and a feedback circuit connected between the output and input of said circuitry for reducing the minimum light intensity requirement for the scan portion remaining for a particle being scanned once said particle indicating signal for such particle is initiated.
Claim 12
Dependent Claim
21 words
A particle detection apparatus according to claim 10 wherein the output of said shift register is connected to said feedback circuit.
Claim 13
Dependent Claim
74 words
A particle detection apparatus according to claim 1 wherein said scanning means includes circuitry for establishing the minimum size that a particle must present to a scan before said particle indicating signal can be produced; and a feedback circuit connected between the output and input of said circuitry for reducing the minimum size requirement for the scan portion remaining for a particle being scanned once said particle indicating signal for such particle is initiated.
Claim 14
Dependent Claim
21 words
A particle detection apparatus according to claim 12 wherein the output of said shift register is connected to said feedback circuit.
Claim 15
Dependent Claim
114 words
A particle detection apparatus according to claim 1 wherein said scanning means includes circuitry having a minimum intensity circuit for establishing the light intensity that a particle must present when scanned before said particle indicating signal can be produced and a minimum size circuit for establishing the minimum width of a particle that must be scanned before said particle indicating signal can be produced; and a feedback circuit connected between the output of said circuitry and the input of said minimum intensity circuit back minimum size circuit for reducing the intensity and size requirements for the scan portion remaining for a particle being scanned once said particle indicating signal for such particle is initiated.
Claim 16
Dependent Claim
21 words
A particle detection apparatus according to claim 14 wherein the output of said shift register is connected to said feedback circuit.
Claim 17
Dependent Claim
84 words
A particle detection apparatus according to claim 1 wherein said scanning means includes a feedback circuit with the output of said shift register connected to the input of said feedback circuit and said synchronizing pulse provided by said scanning means is applied as a clock pulse to said shift register to shift the shift register one clock pulse causing the output of said shift register to be applied to said feedback circuit earlier in each scan subsequent to that first scan of said field.
Claim 18
Dependent Claim
214 words
Particle detection apparatus for determining the number and size of particles present in a plurality of particles dispersed over a field including: scanning means for scanning the field using a succession of scan cycles wherein each scan cycle proceeds across the field at a non-linear rate, said scanning means providing a signal each time a particle in the field is scanned, said signal having a duration dependent on the rate of scan and the width of the particle presented to the scan; said scanning means including a control circuit for providing a signal having a non-linear rate corresponding to the non-linear rate of the scan cycle; signal processing circuitry connected to said scanning means for receiving said first-mentioned signal to provide a particle indicating signal when said first-mentioned signal has a predetermined amplitude and duration; said signal processing circuitry including a minimum size circuit having an integrating circuit portion for producing a signal indicative of the duration of said first-mentioned signal, said integratiNg circuit portion connected to said control circuit for receiving said signal provided by said control circuit for controlling the operation of said integrating circuit whereby said signal indicative of the duration of said first-mentioned signal provided by said integrating circuit portion is proportional to the non-linear rate of each scan cycle.
Claim 19
Dependent Claim
214 words
Particle detection apparatus for determining the number and size of particles present in a plurality of particles dispersed over a field including: scanning means for scanning the field using a succession of scan cycles wherein each scan cycle proceeds across the field at a non-linear rate, said scanning means providing a signal each time a particle in the field is scanned, said signal having a duration dependent on the rate of scan and the width of the particle presented to the scan; said scanning means including a control circuit for providing a signal having a non-linear rate corresponding to the non-linear rate of the scan cycle; signal processing circuitry connected to said scanning means for receiving said first-mentioned signal to provide a particle indicating signal when said first-mentioned signal has a predetermined amplitude and duration; said signal processing circuitry including a minimum size circuit having an integrating circuit portion for producing a signal indicative of the duration of said first-mentioned signal, said integratiNg circuit portion connected to said control circuit for receiving said signal provided by said control circuit for controlling the operation of said integrating circuit whereby said signal indicative of the duration of said first-mentioned signal provided by said integrating circuit portion is proportional to the non-linear rate of each scan cycle.
Claim 20
Dependent Claim
151 words
Particle detection apparatus, which scans a field containing a plurality of particles and produces particle indicating signals in accordance with the size of the particles scanned and the light intensity received from the particles scanned relative to an adjustable intensity threshold, comprising: means for enabling scanning to occur back and forth on a line across an operator selected portion of the field causing particle indicating signals to be produced; means connected to said first-mentioned means for providing a pulse signal for each particle indicating signal produced when scanning said operator selected portion; means connected to said second-mentioned means, including a display means responsive to said pulse signals for providing a single visual indication which varies in proportion to the number of said pulse signals received whereby the intensity threshold can be varied until said single visual indication indicative of the receipt of the maximum number of said pulse signals is established.
Claim 21
Dependent Claim
151 words
Particle detection apparatus, which scans a field containing a plurality of particles and produces particle indicating signals in accordance with the size of the particles scanned and the light intensity received from the particles scanned relative to an adjustable intensity threshold, comprising: means for enabling scanning to occur back and forth on a line across an operator selected portion of the field causing particle indicating signals to be produced; means connected to said first-mentioned means for providing a pulse signal for each particle indicating signal produced when scanning said operator selected portion; means connected to said second-mentioned means, including a display means responsive to said pulse signals for providing a single visual indication which varies in proportion to the number of said pulse signals received whereby the intensity threshold can be varied until said single visual indication indicative of the receipt of the maximum number of said pulse signals is established.
Claim 22
Dependent Claim
26 words
A particle detection apparatus according to claim 18 wherein said second mentioned means is a circuit responsive to the leading edge of the particle indicating signals.
Claim 23
Dependent Claim
26 words
A particle detection apparatus according to claim 18 wherein said second mentioned means is a circuit responsive to the trailing edge of the particle indicating signals.
Claim 24
Dependent Claim
16 words
A particle detection apparatus according to claim 18 wherein said last mentioned means includes an ammeter.
Claim 25
Dependent Claim
99 words
Particle detection apparatus for determining the number of those particles having a predetermined size that are present in a plurality of particles dispersed over a field comprising scanning means for scanning said field in a succession of scan cycles and including circuitry for establishing the minimum size that a particle must present before a particle indicating signal can be produced and a feedback circuit connected between the input and output of said circuitry for reducing the minimum size requirement for the scan portion remaining for a particle being scanned once said particle indicating signal for such particle is initiated.
Claim 26
Dependent Claim
99 words
Particle detection apparatus for determining the number of those particles having a predetermined size that are present in a plurality of particles dispersed over a field comprising scanning means for scanning said field in a succession of scan cycles and including circuitry for establishing the minimum size that a particle must present before a particle indicating signal can be produced and a feedback circuit connected between the input and output of said circuitry for reducing the minimum size requirement for the scan portion remaining for a particle being scanned once said particle indicating signal for such particle is initiated.
Claim 27
Dependent Claim
101 words
Particle detection apparatus for determining the number of those particles having a predetermined size that are present in a plurality of particles dispersed over a field comprising scanning means for scanning said field in a succession of scan cycles and including circuitry for establishing the minimum light intensity that a particle must present before a particle indicating signal can be produced and a feedback circuit connected between the input and output of said circuitry for reducing the minimum light intensity requirement for the scan portion remaining for a particle being scanned once said particle indicating signal for such particle is initiated.
Claim 28
Dependent Claim
101 words
Particle detection apparatus for determining the number of those particles having a predetermined size that are present in a plurality of particles dispersed over a field comprising scanning means for scanning said field in a succession of scan cycles and including circuitry for establishing the minimum light intensity that a particle must present before a particle indicating signal can be produced and a feedback circuit connected between the input and output of said circuitry for reducing the minimum light intensity requirement for the scan portion remaining for a particle being scanned once said particle indicating signal for such particle is initiated.
Claim 29
Dependent Claim
141 words
Particle detection apparatus for determining the number of those particles having a predetermined size that are present in a plurality of particles dispersed over a field comprising scanning means for scanning said field in a succession of scan cycles and including circuitry having a minimum intensity circuit for establishing the light intensity that a particle must present when scanned before a particle indicating signal can be produced and a minimum size circuit for establishing the minimum width of a particle that must be scanned before said particle indicating signal can be produced; and a feedback circuit connected between the output of said circuitry and the input of said minimum intensity circuit and siad minimum size circuit for reducing the intensity and size requirements for the scan portion remaining for a particle once said particle indicating sigNal for such particle is initiated.
Claim 30
Dependent Claim
141 words
Particle detection apparatus for determining the number of those particles having a predetermined size that are present in a plurality of particles dispersed over a field comprising scanning means for scanning said field in a succession of scan cycles and including circuitry having a minimum intensity circuit for establishing the light intensity that a particle must present when scanned before a particle indicating signal can be produced and a minimum size circuit for establishing the minimum width of a particle that must be scanned before said particle indicating signal can be produced; and a feedback circuit connected between the output of said circuitry and the input of said minimum intensity circuit and siad minimum size circuit for reducing the intensity and size requirements for the scan portion remaining for a particle once said particle indicating sigNal for such particle is initiated.
Claim 31
Dependent Claim
53 words
A particle detection apparatus according to claim 24 wherein said apparatus includes a scan cycle memory having its input connected for receiving said particle indicating signals and having its output connected to said feedback circuit, the output of said memory being indicative of the particle indicating signals produced during the preceding scan cycle.
Claim 32
Dependent Claim
17 words
A particle detection apparatus according to claim 25 wherein said scan cycle memory includes a shift register.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-17 | 1978-08-19 | 1979-02-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-17 | 1982-08-19 | 1983-02-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-17 | 1986-08-19 | 1987-02-18 | $7700.00 | Window Closed / Lapsed |