Pathogen detector system and method
First Claim
1. A pathogen detector system, comprising:
- an outer housing having a sample area for containing environmental air;
a light source on one side of the sample area for directing a focused beam of light through the sample air, whereby portions of the beam of light are scattered at various angles by particles of various sizes present in the sample area, and an unscattered portion of the beam of light remains unscattered;
a beam blocking device on the opposite side of the sample area for blocking at least the unscattered portion of the beam of light and directing at least part of the scattered light along a light path;
a first photodetector positioned in the light path after the beam blocking device for detecting light directed by the beam blocking device onto the detector, and producing an output spectrum representing scattering intensity in which the size of each peak is proportional to particle size;
a reflector positioned in front of the beam blocking device in the path of the unscattered portion of the light beam for reflecting at least part of the unscattered portion in a second light paths and a second photodetector positioned to detect light reflected from the reflector;
a differential element responsive to said first and second photodetectors to provide a pulse signal having a scattering peak intensity;
a pulse height discriminator using the scattering peak intensity to characterize particle size, such that the size distribution of airborne particles detected in the air sample at a given time is obtained; and
an alarm unit connected to the pulse height discriminator for providing a warning signal if the number of particles within a predetermined pathogen size range of approximately 1 to 7 μ
m exceeds a predetermined normal level.
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Accused Products
Abstract
A pathogen detector has a sample area for containing environmental air, a light source on one side of the sample area for directing a collimated beam of light through the sample air so that part of the light beam will be scattered by any particles present in the air while the remainder remains unscattered, and a beam blocking device on the opposite side of the sample area for blocking at least the unscattered portion of the beam of light and directing at least part of the scattered light onto a detector. The detector produces output pulses in which each pulse has a height proportional to particle size and a pulse height discriminator obtains the size distribution of airborne particles detected in the air sample at a given time from the detector output. An alarm signal is activated if the number of particles within a predetermined pathogen size range of around 1 to 7 μm exceeds a predetermined normal level.
155 Citations
18 Claims
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1. A pathogen detector system, comprising:
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an outer housing having a sample area for containing environmental air; a light source on one side of the sample area for directing a focused beam of light through the sample air, whereby portions of the beam of light are scattered at various angles by particles of various sizes present in the sample area, and an unscattered portion of the beam of light remains unscattered; a beam blocking device on the opposite side of the sample area for blocking at least the unscattered portion of the beam of light and directing at least part of the scattered light along a light path; a first photodetector positioned in the light path after the beam blocking device for detecting light directed by the beam blocking device onto the detector, and producing an output spectrum representing scattering intensity in which the size of each peak is proportional to particle size; a reflector positioned in front of the beam blocking device in the path of the unscattered portion of the light beam for reflecting at least part of the unscattered portion in a second light paths and a second photodetector positioned to detect light reflected from the reflector; a differential element responsive to said first and second photodetectors to provide a pulse signal having a scattering peak intensity; a pulse height discriminator using the scattering peak intensity to characterize particle size, such that the size distribution of airborne particles detected in the air sample at a given time is obtained; and an alarm unit connected to the pulse height discriminator for providing a warning signal if the number of particles within a predetermined pathogen size range of approximately 1 to 7 μ
m exceeds a predetermined normal level. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A detector apparatus for detecting pathogen particles in a size range of approximately 1 to 7 μ
- m in environmental air, comprising;
a light source for directing a focused beam of light through a sample of environmental air, whereby a first portion of said light beam remains unscattered and a second portion of said light beam is scattered at various angles by particles of various sizes present in the air sample, the scattering angle and scattering cross-section being dependent on the particle size; a beam separating device for separating a predetermined part of the light beam corresponding to light scattered by particles within a predetermined size range from the remainder of the light beam and directing the separated part of the light beam along a light path; a first phototdetector positioned in the light path for detecting said separated part of the light beam and producing a corresponding output signal of electrical pulses representing scattering intensity in which the size of each pulse is proportional to particle size; a reflector positioned in front of the beam separating device in the path of the unscattered portion of the light beam for reflecting at least part of the unscattered portion in a second light path, and a second photodetector positioned to detect light reflected from the reflector; a differential element responsive to said first and second photodetectors to provide a pulse signal having a scattering peak intensity; a pulse height discriminator for using the peak intensity to characterize particle size; and a control unit connected to the discriminator output for generating an alarm signal if the detected number of particles within a range of approximately 1 to 7 μ
m in size exceeds a predetermined value. - View Dependent Claims (8, 9, 10, 11)
- m in environmental air, comprising;
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12. A method of detecting airborne pathogens, comprising the steps of:
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directing a light beam from a light source through a sample of environmental air such that a first portion of the light beam is scattered by particles present in the sample and a second portion remains unscattered; receiving both portions of the light beam which have passed through the air sample and directing the light beam portions onto a beam blocking device; blocking at least the second portion of the light beam at the beam blocking device and directing at least part of the first portion of the light beam onto a first detector; measuring the pulse height of electrical pulses output from the first detector; reflecting at least part of the second portion of the light beam onto a second detector, connecting the output of the second detector to a power monitor for detecting decrease in light source output power; counting the number of pulses of each pulse height in a predetermined time interval; converting the pulse heights to particle sizes; and producing an alarm signal if the number of pulses detected within a predetermined size range corresponding to pathogen-size particles is exceeded;
or if the light source power falls below a predetermined level. - View Dependent Claims (13, 14, 15, 16, 17, 18)
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Specification