Particle counting method

• US 8,497,989 B2
• Filed: 11/30/2011
• Issued: 07/30/2013
• Est. Priority Date: 11/30/2010
• Status: Active Grant

• Current Assignee: RION Company Limited
• Original Assignee: RION Company Limited
• Inventors: Imai, Takehiro, Matsuda, Tomonobu, Abe, Toshiyuki, Nakajima, Tsutomu
• Primary Examiner(s): NGUYEN, SANG H
• Application Number:
  US13/307,318
• Publication Number:
  US 20120133936A1
• Time in Patent Office: 608 Days
• Field of Search: 356335-343, 356432-441
• US Class Current: 356/338
• CPC Class Codes: G01N 15/1429 Signal processing
• CPC Class Codes: G01N 15/1459 the analysis being performed on a sample stream
• CPC Class Codes: G01N 2015/1486 Counting the particles

Abstract

A particle counting method that can count the number of the particles precisely. The method discriminates a wave pattern of the scattered light from a normal particle (subject of the counting) and a wave pattern of the light scattered by the agitation such as a floating particle, a radiation or changes in the intensity of the light. In one embodiment, a method for counting particles is disclosed which irradiates a light to a sample gas, detects a scattered light from a particle included in the sample gas by a photoelectric conversion device, counts the number of the particles of every particle size division by the output voltage wave pattern of the photoelectric conversion device, calculate a time difference (Ta−T1) from a point (T1) being a peak of output voltage wave pattern and a point (Ta) being a falling detection threshold (A), when the time difference (Ta−T1) is beyond counting cancellation time (B), the output voltage wave pattern is not counted as a particle.

Claims

1. A method of particle counting, the method comprising:

irradiating a sample gas with a light;

detecting a scattered light from a particle included in the sample gas by a photoelectric conversion device;

counting a number of the particles of every particle size division by an output voltage wave pattern of the photoelectric conversion device; and

calculating, with a Digital Signal Processor (DSP), a time difference (Ta−

T1) with a point (T1) of a peak of output voltage wave pattern and a point (Ta) of a falling detection threshold (A), when the time difference (Ta−

T1) exceeds a counting cancellation time (B), the output voltage wave pattern is not counted as a particle.

4. A method of particle counting according to any one of claims 1-3, wherein, the falling detection threshold (A), the counting cancellation time (B) and the predetermined voltage value (C) are modifiable.

2. A method of particle counting, the method comprising:

irradiating a sample gas with a light;

detecting a scattered light from a particle included in the sample gas by a photoelectric conversion device;

counting a number of the particles every particle size division by an output voltage wave pattern of the photoelectric conversion device, wherein the output voltage wave pattern has a plurality of peaks, and wherein a voltage value difference of each peak (Px) and a dip (Dx−

1) just before that of the peak exceeds a predetermined voltage value (C); and

calculating, with a Digital Signal Processor (DSP), a time difference (Ta−

Txm) with a point (Ta) of a falling detection threshold (A) and a point (Txm) just before that of the peak (Pxm), when the time difference (Ta−

Txm) exceeds a counting cancellation time (B), the output voltage wave pattern is not counted as a particle.

3. A method of particle counting according to claim 2, wherein, when the voltage value difference of each peak (Px) and the dip (Dx−

1) just before that of the peak does not exceed a predetermined voltage value (C), the peak of output voltage wave pattern is not a peak from a particle.