PARTICLE COUNTING METHOD

• US 20120133936A1
• Filed: 11/30/2011
• Published: 05/31/2012
• 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
• Granted Patent: US 8,497,989 B2
• Time in Patent Office: Days
• 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 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, and counts a 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) 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 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 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 a number of the particles every particle size division by the output voltage wave pattern of the photoelectric conversion device,

The output voltage wave pattern has a plurality of peaks, and a voltage value difference of each peak (Px) and the dip (Dx−

1) just before of the peak exceeds a predetermined voltage value (C),

Calculate 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.