# US 10,119,908 B2 · Particle sensor > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,119,908 B2 - Document ID: US10119908B2 - Status: Granted - Kind: B2 - Application number: 15/383,155 - Filed: 2016-12-19 - Published: 2017-06-22 - Granted: 2018-11-06 - Earliest claimed: 2015-12-21 - Assignees: Panasonic Intellectual Property Management Co., Ltd. - Applicants: Panasonic Intellectual Property Management Co., Ltd. - Inventors: Shintaro Hayashi; Shinichi Kitaoka; Hirotaka Matsunami - Web page: https://patentgrep.com/patent/US10119908B2 ## CPC - G01N 21/53: within a flowing fluid, e.g. smoke - G01J 1/0214: {Constructional arrangements for removing stray light} - G01J 1/0418: {using attenuators} - G01N 15/1459: {the analysis being performed on a sample stream} - G01N 15/075: by optical means - G01N 2015/0046: {in gas, e.g. smoke} - G01N 2015/1486: {Counting the particles} - G01N 2021/473: {Compensating for unwanted scatter, e.g. reliefs, marks} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G01J: MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY (light sources F21, H01J, H01K, H05B; investigating properties of materials by optical means G01N) ## Abstract A particle sensor is provided. The particle sensor includes a light projector that projects light to a detection area. A light receiver receives scattered light. The scattered light is light from the light projector that has been scattered by particles in the detection area. A first reflector reflects the scattered light to the light receiver. A light attenuator attenuates stray light that exits the first reflector. The first reflector includes a first aperture that introduces the light from the light projector into an interior of the first reflector and a second aperture that exits the stray light from the first reflector. The light attenuator includes a third aperture through which the stray light that exits the first reflector passes. An aperture area of the third aperture is smaller than an aperture area of the second aperture. ## Claims ### Claim 1 A particle sensor, comprising: a light projector that projects light to a detection area; a light receiver that receives scattered light, the scattered light being light from the light projector that has been scattered by particles in the detection area; a first reflector that reflects the scattered light to the light receiver; a light attenuator that attenuates stray light that exits the first reflector, wherein the first reflector includes a first aperture that introduces the light from the light projector into an interior of the first reflector and a second aperture that exits the stray light from the first reflector, the light attenuator includes a third aperture through which the stray light that exits the first reflector passes, and an aperture area of the third aperture is smaller than an aperture area of the second aperture; and a second reflector that reflects, to the third aperture, the stray light that exits the first reflector. ### Claim 2 (depends on 1) The particle sensor according to claim 1, wherein a barrier is disposed on a line connecting the second aperture and the third aperture. ### Claim 3 (depends on 1) The particle sensor according to claim 1, wherein the first reflector is spaced from the second reflector. ### Claim 4 (depends on 1) The particle sensor according to claim 1, wherein the light attenuator includes a first space and a second space which receive the stray light in order, and the second space is a closed space. ### Claim 5 (depends on 4) The particle sensor according to claim 4, wherein a protrusion is disposed at an edge of the third aperture, on a second space side of the third aperture. ### Claim 6 (depends on 1) The particle sensor according to claim 1, wherein the first aperture and the second aperture are aligned with an optical axis of the light projector. ### Claim 7 (depends on 1) The particle sensor according to claim 1, wherein the light attenuator includes a first space and a second space which receive the stray light in order, and the third aperture interconnects the first space and the second space. ### Claim 8 (depends on 7) The particle sensor according to claim 7, wherein the second reflector is disposed in the first space. ### Claim 9 (depends on 8) The particle sensor according to claim 8, wherein the first aperture, the second aperture, and the second reflector are aligned with an optical axis of the light projector. ### Claim 10 (depends on 8) The particle sensor according to claim 8, wherein the light attenuator further includes a protrusion in the second space, the protrusion being disposed on an edge of the third aperture. ### Claim 11 (depends on 10) The particle sensor according to claim 10, wherein the protrusion extends into the second space of the light attenuator parallel to an axis of the third aperture. ### Claim 12 (depends on 10) The particle sensor according to claim 10, wherein the second space of the third aperture is defined by three wall surfaces, the third aperture extends through one of the three wall surfaces, the protrusion is disposed on the one of the three wall surfaces on the edge of the protrusion, and the three wall surfaces form a right triangle. ### Claim 13 (depends on 12) The particle sensor according to claim 12, wherein the right triangle formed by the three wall surfaces includes angles of thirty degrees, sixty degrees, and ninety degrees. ### Claim 14 (depends on 12) The particle sensor according to claim 12, wherein the one of the three wall surfaces that includes the third aperture and the protrusion is a leg of the right triangle. ### Claim 15 (depends on 1) The particle sensor according to claim 1, wherein the first reflector includes an elliptical mirror, the elliptical mirror including an inner surface that forms a segment of a spheroid. ### Claim 16 A particle sensor, comprising: a light projector that projects light to a detection area; a light receiver that receives scattered light, the scattered light being light from the light projector that has been scattered by particles in the detection area; a first reflector that reflects the scattered light to the light receiver; and a light attenuator that attenuates stray light that exits the first reflector, wherein the first reflector includes a first aperture that introduces the light from the light projector into an interior of the first reflector and a second aperture that exits the stray light from the first reflector, the light attenuator includes a third aperture through which the stray light that exits the first reflector passes, an aperture area of the third aperture is smaller than an aperture area of the second aperture, wherein the first reflector includes an elliptical mirror, the elliptical mirror including an inner surface that forms a segment of a spheroid, and wherein the inner surface of the elliptical mirror includes a cross-sectional shape of a segment of an ellipse, and among two focal points that define the ellipse, a first focal point is located in the detection area and a second focal point is located in a center of the light receiver. ### Claim 17 (depends on 16) The particle sensor according to claim 16, wherein the ellipse includes a major axis of 20 millimeters to 100 millimeters and a minor axis of 10 millimeters to 50 millimeters. ### Claim 18 (depends on 1) The particle sensor according to claim 1, wherein the light projector includes a light emitting diode or a laser diode, and the light receiver includes a photodetector. ### Claim 19 A particle sensor, comprising: a light receiver configured to receive scattered light, the scattered light being light from a light projector that has been scattered by particles in a detection area; a first reflector configured to reflect the scattered light to the light receiver; a light attenuator configured to attenuate stray light that exits the first reflector, wherein the first reflector includes a first aperture configured to introduce the light from the light projector into an interior of the first reflector and a second aperture configured to exit the stray light from the first reflector, the light attenuator includes a third aperture configured to receive the stray light that exits the first reflector, and a cross-sectional area of the third aperture is smaller than a cross-sectional area of the second aperture; and a second reflector that reflects, to the third aperture, the stray light that exits the first reflector. ### Claim 20 (depends on 1) The particle sensor according to claim 1, wherein the stray light that enters the light attenuator is unwanted light. ### Claim 21 (depends on 19) The particle sensor according to claim 19, wherein the stray light that enters the light attenuator is unwanted light.