Light scattering measurement based on multiple light sources

Abstract

The embodiment of the invention relates to light scattering measurement based on multiple light sources. In some examples, the techniques are implemented as an apparatus that includes first and second light sources (120, 130), a light detector (110) having a detector output, and processing circuitry (180) having a processing input coupled to the detector output and a processing output. The first light source (120 or 130) is configured to generate a first light signal having a first wavelength. The second light source (120 or 130) is configured to generate a second light signal having a second wavelength different from the first wavelength. The light detector (110) is configured to generate a first detection signal at the detector output in response to the first light signal and a second detection signal at the detector output in response to the second light signal. The processing circuit (180) is configured to generate a third signal representative of an air quality measurement at the processing output in response to the first detection signal and the second detection signal.

Description

Technical Field

[0001] Embodiments of the present application relate to air quality sensing, and more particularly to light scattering measurements based on multiple light sources. Background Art

[0002] Light scattering may occur when light propagates through particles in the space (e.g., smoke particles) and is scattered by the particles in the space. A light scattering measurement device may emit light into the space and sense the light propagating through the space to measure the scattering of the light (if any). Based on the measurement results, it may be detected whether certain particles of interest are present in the space. Summary of the invention

[0003] In some examples, an apparatus includes a first light source, a second light source, a light detector having a detector output, and a processing circuit having a processing input and a processing output, the processing input being coupled to the detector output. The first light source is configured to generate a first light signal having a first wavelength. The second light source is configured to generate a second light signal having a second wavelength, the second wavelength being different from the first wavelength. The light detector is configured to generate a first detection signal at the detector output in response to the first light signal, and to generate a second detection signal at the detector output in response to the second light signal. The processing circuit is configured to generate a third signal representing an air quality measurement at the processing output in response to the first detection signal and the second detection signal.

[0004] In some examples, a method includes emitting a first light signal having a first wavelength with a first light source. The method also includes emitting a second light signal having a second wavelength different from the first wavelength with a second light source. The method also includes generating a first detection signal by a light detector in response to the first light signal. The method also includes generating a second detection signal by the light detector in response to the second light signal. The method also includes generating a third signal representing an air quality measurement result by a processing circuit in response to the first detection signal and the second detection signal.

[0005] In some examples, a computer-readable medium includes computer-executable instructions that are executable by a processor to configure the processor to: receive a first detection signal, the first detection signal representing detection of a first optical signal having a first wavelength; receive a second detection signal, the second detection signal representing detection of a second optical signal having a second wavelength; and generate a third signal representing an air quality measurement at the processing output in response to the first detection signal and the second detection signal. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1is a block diagram of an air quality sensing system according to various examples.

[0007] Figure 2 is a block diagram of processing circuitry of an air quality sensing system according to various examples.

[0008] Figure 3 is a block diagram of a particle size estimation module according to various examples.

[0009] Figure 4 is a flow chart of an air quality measurement method according to various examples.

[0010] Figure 5 is a flow chart of another air quality measurement method according to various examples.

[0011] Figure 6 is a flow chart of a simulation process for angle configuration optimization according to various examples.

[0012] Figure 7 Included are graphs illustrating curve fitting used by an air quality sensing system according to various examples.

[0013] Figure 8 is a block diagram of an example computing device that can perform air quality measurement methods according to various examples.

[0014] In this specification, the same reference numerals depict the same or similar (in function and / or structure) features.The drawings are not necessarily drawn to scale. DETAILED DESCRIPTION

[0015] Technology for air quality sensing is described herein. In an example, the technology is implemented as a device configured for sensing air quality. The device can be, for example, a smoke detector or other air quality sensor. In some examples, the device includes a first light source, a second light source, a light detector having a detector output, and a processing circuit having a processing input and a processing output, the processing input being coupled to the detector output. The first light source is configured to generate a first light signal having a first wavelength. The second light source is configured to generate a second light signal having a second wavelength, the second wavelength being different from the first wavelength. The light detector is configured to generate a first detection signal at the detector output in response to the first light signal, and to generate a second detection signal at the detector output in response to the second light signal. The processing circuit is configured to generate a third signal representing an air quality measurement result at the processing output in response to the first detection signal and the second detection signal.

[0016] As described above, the light scattering measurement device emits light into the space and senses the light propagating through the space to measure the scattering of the light (if any). Based on the measurement results, it can be detected whether certain particles of interest are present in the space. For example, a smoke detector can transmit light from an LED, which is reflected or scattered by smoke particles and then detected by a photodiode. If the received signal provided by the photodiode exceeds a suitable threshold, a smoke detection alarm can be generated. These devices do not provide any air quality indication, such as particle size and mass concentration.

[0017] As will be described herein, an example of an air quality sensing system may include multiple light sources to provide light scattering measurements, which may be further processed to provide particle size and mass concentration information. In some examples, an air quality sensing system may include two light sources operating at different wavelengths and oriented to provide preconfigured scattering angles. The light emitted by the two light sources may be reflected from particles of interest (e.g., smoke particles) as part of backscattering, and the ratio of the intensities of the two backscattered light signals may exhibit a monotonic trend that depends on the average particle size of the particles. As described herein, this monotonic trend may be used to estimate particle size and particle concentration. In addition, techniques for determining the appropriate wavelength and orientation of the light source will also be disclosed.

[0018] The described techniques allow the use of optical hardware resources (e.g., LEDs and photodiodes) of a smoke detector that support light scattering measurements to support air quality measurements. This arrangement allows an air quality sensor to use similar optical hardware resources as a smoke detector, which can reduce the hardware complexity and cost of the air quality sensor.

[0019] Figure 1 1 is a block diagram of an air quality sensing system 100 according to various examples. The air quality sensing system 100 includes a processing circuit 180, two light sources 120 and 130, and a light detector 110. The processing circuit 180 has a processing input and a processing output. The processing input is coupled to the light detector 110. In an example, the processing output is coupled to a device (not shown) to which the air quality sensing system 100 provides air quality measurements. The processing circuit 180 can be any suitable circuit or component capable of performing processing and / or control, such as a processor, a microprocessor, a controller, a microcontroller unit (MCU), a field programmable gate array (FPGA), or any other combination of analog and / or digital components arranged in an architecture that provides processing and control capabilities.

[0020] In some examples, light sources 120 and 130 are light emitting diodes (LEDs) configured to generate light signals having first and second wavelengths, respectively, the second wavelength being different from the first wavelength. In some examples, the first wavelength is in the infrared spectral region and the second wavelength is in the blue spectral region. In other examples, light sources 120 and 130 can be any other suitable light source other than LEDs. In some examples, light detector 110 includes a photodiode. In other examples, light detector 110 is any device capable of providing an output signal in response to detection of light.

[0021] In example operation, light sources 120 and 130 emit light signals that are scattered or reflected by particles such as particles 140 (e.g., smoke particles, pollutants, or any scattering agent of interest). Light at a first wavelength from first light source 120 is shown as backscattering angle φ in the forward direction (e.g., less than 90 degrees). 1 (also labeled as angle 150) as backscattered light signal 145a. Light at a second wavelength from second light source 130 is shown as being backscattered in a backward direction (eg, greater than 90 degrees) at an angle Φ 2 (also labeled as angle 160) as backscattered light signal 145b. In some examples, first light source 120 is oriented to have a forward backscatter angle φ in the range of 50 to 60 degrees. 1 A first light signal is generated, and a second light source is directed to backscatter at an angle Φ in the range of 145 to 155 degrees. 2 A second optical signal is generated.

[0022] Some or all of the backscattered light 145a and 145b from the two light sources may be detected by the photodetector 110. The photodetector 110 outputs a detection signal 170 representing the detected backscattered light signal 145a from the first light source and the detected backscattered light signal 145b from the second light source. The detection signal 170 is provided to the processing circuit 180 (e.g., by processing the input). The processing circuit 180 may generate an air quality measurement result 190 (e.g., at the processing output), which may include the size of the particles and / or the mass concentration of the particles. In some instances, the air quality measurement result may also include an indication of smoke detection. In some instances, for the purpose of air quality measurement and smoke detection, the particle size of interest may be in the range of about 300 nanometers (nm) to 10 micrometers (μm). The calculation of the particle size and mass concentration may be based on the ratio between the intensity of the detected backscattered light signal 145a and the intensity of the backscattered light signal 145b, as will be described below.

[0023] In some examples, the air quality sensing system 100 may include a chamber that houses the light sources 120 and 130 and the light detector 110. The chamber may block ambient light outside the chamber from reaching the light detector 110 while allowing particles to enter the chamber through an opening of the chamber and scatter the light emitted by the light sources 120 and 130. The ambient light may have an intensity that varies over time and may introduce an interference component into the detection signal 170 if the ambient light is received by the light detector 110. By blocking the ambient light from reaching the light detector 110, the interference component may be reduced, which may improve the accuracy of the detection / measurement operation.

[0024] In some examples, the air quality sensing system 100 can operate in a chamberless or partially chamberless arrangement, in which case the light detector 110 is exposed to more ambient light than if the light detector 110 is housed in a chamber. The chamberless (or partially chamberless) arrangement helps particles (including low momentum particles that might otherwise be blocked by the chamber) move into the space between the light sources 120 and 130 and the light detector 110, and helps improve the sensitivity of the air quality sensing system 100 in detecting / measuring such particles. The chamberless (or partially chamberless) arrangement can also reduce the manufacturing complexity and cost of the air quality sensing system 100.

[0025] Figure 2 is a block diagram of a processing circuit 180 of an air quality sensing system 100 according to various examples. The processing circuit 180 is shown to include a particle size estimation module 200, a particle concentration calculation module 230, a mass concentration module 250, and a total mass concentration module 270. Each of these modules may be a circuit module or a software module.

[0026] The particle size estimation module 200 is configured to calculate the power or intensity (I 0 ) and the detected power or intensity (I 1 ) between the two. Then, the average size or average particle diameter d of the particles 210 is estimated based on R. p , combined with the following Figure 3 Explained.

[0027] The particle concentration calculation module 230 is configured to calculate the particle concentration N(d p )(exist Figure 2 For example, N(d p ) can be expressed as having an average size d per cubic meter p Based on the total intensity of the backscattered light received by the light detector 110 (which can be obtained by I 0 +I 1 Represents) with diameter d p N(d p ). In some examples, the expected scattered power or intensity 220 based on one or both of the light sources can be obtained from simulations or experiments.

[0028] The mass concentration module 250 is configured to calculate the average size d p The mass concentration of particles m(d p )260. For example, m(d p ) can represent the mass of particles in micrograms per cubic meter. Based on the particle concentration N(d p ), particle volume v p and particle density ρ p The mass concentration m(d p ). Volume v p Calculated as Density ρ p It can be obtained by calibration or other suitable means. Therefore, the approximate value of mass concentration 260 can be calculated based on the average particle size:

[0029]

[0030] Figure 3 is a block diagram of a particle size estimation module 200 according to various examples. The particle size estimation module 200 is shown to include a ratio calculation module 300, a curve fitting module 310, and a lookup table 320.

[0031] The ratio calculation module 300 is configured to calculate the power or intensity (I 0 ) and the detected power or intensity (I 1 ) between the ratio R (in Figure 3 (also labeled 305 in FIG. 1 ). In some examples, R may be calculated as:

[0032] R=I 0_norm / I 1_norm (Equation 2)

[0033] Among them I 0_norm and I 1_norm is the normalized intensity (eg, the intensity or power incident on the detection region of the light detector 110). In some examples, it is also possible to calculate the intensity based on I 0 with I 1 R is calculated by the ratio between 0_norm and I 1_norm (and intensity I 0 and I 1 ) depends on the particle concentration N(d p), and N(d p ) factor, so that the ratio can depend on the particle diameter d p , and does not depend on the particle concentration.

[0034] The curve fitting module 310 is configured to calculate the average particle size d according to R p This exploits the monotonic relationship between the ratio and the average particle size (for a particular set of wavelengths, e.g., blue / IR, green / IR, etc.), as described below in conjunction with Figure 7 In some examples, the average particle size can be calculated using a polynomial curve fit as:

[0035] d p =p 0 +p 1 R+…+P n R n (Equation 3)

[0036] In equation 3, p 0 、p 1 ,...p n are the coefficients of a polynomial relating the intensity ratio to the average particle size. The polynomial coefficients may be determined by a calibration or simulation process in which the intensity ratio is calculated for a series of particles of known size and the resulting ratio is fit to a curve described by the polynomial using linear regression or any other suitable technique according to the present disclosure. In some examples, the particle diameter d p can have a monotonic relationship with R.

[0037] In some examples, as an alternative to performing a curve fitting process for each measured ratio, a lookup table (LUT) 320 may be used to provide d as a function of R. p (For example, the LUT provides a mapping between intensity ratios and particle sizes). The d stored in the LUT may be pre-calculated using curve fitting or by any other suitable means according to the present disclosure. p Values, which are indexed by R.

[0038] In some examples, the LUT (or other hardware) may store d p and the ratios R obtained from different combinations of wavelengths of backscattered light. p can be mapped to a first set of ratios R between the intensities of the backscattered blue light and the infrared light, and a second set d p can be mapped to a second set of ratios R between the intensities of the backscattered green and infrared light to provide d pA monotonic relationship between R and R. In such an example, the air quality sensing system 100 may include a plurality of LEDs to provide blue light, green light, and infrared light to perform air quality measurement.

[0039] The process described above may be performed by the particle concentration calculation module 230 and the mass concentration calculation module 250 and is summarized as follows:

[0040] Received scattering intensity It can be calculated as an approximate value by the particle concentration calculation module 230 as follows:

[0041]

[0042] In equation 4, represents the average particle size, and Represents a value of size d p The expected scattered power or intensity 220 of a single particle, as described above. can be a parameter known from simulation. can be based on the received scattering intensity and Determined by the ratio between

[0043] In some instances, to determine It is possible to use a sample containing a sample with a known concentration of N ref and a reference sensor (e.g., air quality sensing system 100) of particles with known particle diameters (or average particle diameters) to perform a calibration operation, wherein the backscattered light intensity is measured as the simulated light intensity I SIM Based on equation 4 above, I SIM Also available with and Based on equation 4, different intensities I can be generated for different particle diameters (or average particle diameters). SIM , and can be obtained from different strengths I SIM and known concentration N ref Determine the difference Value. Different Value (and / or I SIM values) can be mapped to different particle diameters in memory (e.g., a lookup table)

[0044] To determine The simulated light intensity I for a particular average particle diameter may be retrieved from memory based on the known particle diameter (determined based on R, as described above). SIM or In some examples, based on Equation 4 above, it is possible to SIM The measured backscattered light intensity (I0 +I 1 ) and can be determined based on the scaled measured backscattered light intensity (I 0 +I 1 )(scaled by k) and Determined by the ratio between In some examples, the backscattered light intensity (I 0 +I 1 )and Determined by the ratio between and The value may then be provided to mass concentration calculation module 250, which may calculate the mass concentration m based on Equation 1, as described above.

[0045] Figure 4 4 is a flow chart of an air quality measurement method 400 according to various examples. In some examples, the method 400 is implemented by the air quality sensing system 100 via one or more components of the air quality sensing system 100. The method 400 can be implemented to provide air quality measurements based on the detection of two or more light signals having different wavelengths. In some examples, the method 400 is implemented as computer-executable instructions stored on a non-transitory computer-readable medium. The computer-executable instructions can be executed by a processor or a processing circuit (e.g., processing circuit 180) to cause the processor to perform the operations of the method 400.

[0046] At operation 410, a first light source emits a first light signal having a first wavelength. In some examples, the first light source is an LED, and the first wavelength is in the infrared spectral region.

[0047] At operation 420, the second light source emits a second light signal having a second wavelength, the second wavelength being different from the first wavelength. In some examples, the second light source is an LED, and the second wavelength is in the blue spectral region.

[0048] At operation 430, a first detection signal is generated by a light detector in response to scattering of the first light signal by one or more particles. In some examples, the light detector is a photodiode.

[0049] At operation 440 , a second detection signal is generated by the light detector in response to scattering of the second light signal by the one or more particles.

[0050] At operation 450, a third signal is generated in response to the first detection signal and the second detection signal. The third signal represents an air quality measurement and may include one or more of the size of the particle and the mass concentration of the particle. As described above, the processing circuit may determine an intensity ratio between the first light signal and the second light signal based on the first detection signal and the second detection signal, and then determine the particle size and / or mass concentration based on the intensity ratio.

[0051] Figure 5 is a flow chart of another air quality measurement method 500 according to various examples. In some examples, the method 500 is implemented by the air quality sensing system 100 via one or more components of the air quality sensing system 100. The method 500 can be implemented to provide air quality measurements based on the detection of two or more light signals having different wavelengths. In some examples, the method 500 is implemented as computer-executable instructions stored on a non-transitory computer-readable medium. The computer-executable instructions can be executed by a processor or a processing circuit (e.g., processing circuit 180) to cause the processor to perform the operations of the method 500.

[0052] At operation 510, a first detection signal is received. The first detection signal represents detection of a first optical signal having a first wavelength. In some examples, the first wavelength is in the infrared spectral region.

[0053] At operation 520, a second detection signal is received. The second detection signal represents detection of a second optical signal having a second wavelength. In some examples, the second wavelength is in the blue spectral region.

[0054] At operation 530, a third signal is generated at the processing output. The third signal represents an air quality measurement and may include one or more of the size of the particle and the mass concentration of the particle. As described above, the processing circuit may determine an intensity ratio between the first light signal and the second light signal based on the first detection signal and the second detection signal, and then determine the particle size and / or mass concentration based on the intensity ratio.

[0055] Figure 6 is a flow chart of a process method 600 for determining the backscattered light intensity ratio (R) of two LEDs and the particle diameter (d p ), and determine the forward and backward backscatter angle configuration for the air quality sensing system. In some examples, method 600 may be implemented by a system configured to determine the appropriate forward backscatter angle and backward backscatter angle for configuring the geometric layout of the light source and light detector of the air quality sensing system 100, as previously described. In such examples, the forward scatter angle φ may be adjusted 1 and the backscattering angle Φ 2In some examples, method 600 is performed by a processor / processing circuit (eg, processing circuit 180 or other processing circuit) when the processor or processing circuit executes computer-executable instructions stored on a non-transitory computer-readable medium.

[0056] At operation 602 , the processing circuit 180 may control first and second light sources (eg, light sources 120 and 130 ) to project light having first and second wavelengths to particles having different particle sizes at different forward and backward backscattering angles, respectively.

[0057] Specifically, as part of operation 602, different forward and backscatter angles Φ may be selected from the range of angles: 1 and the backscattering angle Φ 2 In some examples, the angle is selected from a range of 0 to 360 degrees in increments or increments of one degree. p ). In some examples, the particle size may be in the range of 0.3 μm to 10 μm. For each combination of a specific forward and backward backscattering angle and a specific particle size, the processing circuit 180 may control the first light source and the second light source to project two wavelengths of light to particles of the particle size at the forward and backward backscattering angles according to the combination. Operation 602 may be repeated for different combinations of forward and backward backscattering angles and particle sizes.

[0058] At operation 604, the processing circuitry may determine a photodetector output (e.g., the output of light detector 110) for each combination of forward and backward backscatter angles and particle size. The photodetector output may represent the intensity of backscattered light received by the photodetector for a particular combination of forward and backward backscatter angles and particle size.

[0059] At operation 606, the processing circuit may determine from the photodetector output a first scattered power P of light having a first wavelength for different particle sizes. 1 and a second scattered power P of light having a second wavelength 2 .

[0060] Specifically, each light source (e.g., LED) may have a radiated power distribution that relates the radiated power of the light source to wavelength and angular displacement. The photodetector may also have a received power distribution that relates the received power to wavelength and angular displacement. In order to determine the scattered power P 1, the photodetector output (which represents the intensity of the backscattered light) at each forward backscatter angle and particle size can be scaled by a scaling factor based on a given angular shift (based on the forward backscatter angle) for the radiated power distribution from the first LED and the received power distribution at the photodetector and the radiated power and received power for a given particle size. The scaled intensities can then be summed to give a value for a particular particle size d p The scattered power P 1 .

[0061] In addition, in order to determine the scattered power P 2 , the photodetector output at each backscattering angle and particle size can be scaled by a scaling factor based on the radiated power and received power for a given angular displacement (based on the backscattering angle) for the radiated power distribution from the second light source and the received power distribution at the photodetector and for a given particle size. The scaled intensities can then be summed to give a value for a particular particle size d p The scattered power P 2 .

[0062] At operation 608, the processing circuit may calculate the ratio R for different particle sizes as R(d p )=P 1 / P 2 , which is equivalent to the ratio of the received intensity.

[0063] At operation 610, after R(d p ), the processing circuit can determine the relationship between the ratio and the particle size. The processing circuit can perform curve fitting, linear regression operations, etc. to determine the relationship. Example curve fitting is described below. Figure 7 This is explained in the.

[0064] At operation 612, the processing circuit may determine a forward backscatter angle configuration and a backward backscatter angle configuration of the air quality sensing system based on the relationship.

[0065] Specifically, the processing circuitry may determine, for each combination of forward and backward backscatter angles, a mean square error (MSE) between a set of known particle sizes used in operations 602-606 and a set of particle sizes calculated using the relationship and the R ratio for a particular combination of forward and backward backscatter angles. The particular combination of forward and backward backscatter angles that provides the minimum MSE among all combinations may then be selected as the forward backscatter angle configuration and the backward backscatter angle configuration for the air quality sensing system.

[0066] Figure 7A graph 700 illustrating curve fitting used by an air quality sensing system according to various examples is included. Figure 7 , the power ratio R(d p ) 710 is plotted as a line 730 depending on the particle diameter 720 expressed in μm. The curve is fitted to line 740 at point 730. The fit points may be generated using any suitable curve fitting technique, including, for example, linear regression. In some examples, the graph 710 may include power ratios of light having different wavelength pairs for different parameter sizes. For example, for a first parameter size range, the graph 710 may include a power ratio of blue light to IR, and for a second parameter size range, the graph 710 may include a power ratio of green light to IR to extend the monotonic relationship between power ratio and particle size.

[0067] Figure 8 is a block diagram of an example computing device or platform 800 that may be part of air quality sensing system 100. Hardware computing system 800 includes a number of example subsystems. Figure 8 The subsystems shown in FIG. 8 are interconnected via a system bus 880. Additional subsystems such as a storage device 830, a user interface 860, a monitor 870, etc. are shown. Peripheral devices and I / O devices coupled to an input / output (I / O) controller 850 may be connected through, for example, an input / output (I / O) port (e.g., a universal serial bus "USB", ) are connected to the hardware computing system. External interface 890 (e.g., Ethernet, Wi-Fi, etc.) can be used to connect the hardware computing device 800 to a wide area network such as the Internet, a mouse input device, or a scanner. Interconnection via system bus 880 allows central processor 810 (which can be or include processing circuit 180) to communicate with each subsystem and control the execution of multiple instructions from system memory 820 or storage device 830 (e.g., a fixed disk such as a hard disk or optical disk) and the exchange of information between subsystems. System memory 820 and / or storage device 830 can embody computer-readable media. In some instances, central processor 810 can execute instructions stored in system memory 820 and / or storage device 830 to perform the example calculations and methods described above with respect to any of the foregoing figures herein, including processes 400, 500, and 600. Central processor 810 can use system memory 820 to store input data, output data, and intermediate data generated from the execution of the method. Another subsystem is data collection device 840, which can be configured to collect data from, for example Figure 1 The light detector of the light detector 110 receives the data. Any of the data described herein may be output from one component to another component and may be provided to a user.

[0068] The hardware computing system may include identical components or subsystems connected together, for example, via external interface 890 or via internal interfaces. In some embodiments, the hardware computing system, subsystem, or device may communicate via a network. In this case, one computer may be a client and the other computer may be a server, each of which may be part of the same computer system. The client and server may each include multiple systems, subsystems, or components.

[0069] In this specification, the term "coupled" may encompass connections, communications, or signal paths that achieve a functional relationship consistent with this specification. For example, if device A generates a signal to control device B to perform an action, then: (a) in a first instance, device A is coupled to device B through a direct connection; or (b) in a second instance, device A is coupled to device B through an intermediate component C, provided that the intermediate component C does not change the functional relationship between device A and device B, so that device B is controlled by device A via the control signal generated by device A.

[0070] A device "configured to" perform a task or function may be configured (e.g., programmed and / or hardwired) to perform the function when manufactured by a manufacturer, and / or may be configurable (or reconfigurable) by a user after manufacture to perform the function and / or other additional or alternative functions. Configuration may be through firmware and / or software programming of the device, through the construction and / or layout of the device's hardware components and interconnections, or a combination thereof.

[0071] Circuits or devices described herein as including certain components may alternatively be coupled to those components to form the described circuit systems or devices. For example, a structure described as including one or more semiconductor elements (e.g., transistors), one or more passive elements (e.g., resistors, capacitors, and / or inductors), and / or one or more sources (e.g., voltage sources and / or current sources) may alternatively include only semiconductor elements within a single physical device (e.g., a semiconductor die and / or an integrated circuit (IC) package), and may be coupled to at least some of the passive elements and / or sources to form the described structure at the time of manufacture or after manufacture, for example, by an end user and / or a third party.

[0072] Although some components may be described herein as belonging to a specific process technology, these components may be exchanged with components of other process technologies. The circuit described herein may be reconfigured to include a replacement component to provide functionality at least partially similar to functionality available before component replacement. Unless otherwise specified, components shown as resistors generally represent any one or more elements coupled in series and / or in parallel to provide the impedance amount represented by the resistor shown. For example, a resistor or capacitor shown and described as a single component in this article may alternatively be a plurality of resistors or capacitors coupled in parallel between the same nodes. For example, a resistor or capacitor shown and described as a single component in this article may alternatively be a plurality of resistors or capacitors coupled in series between two nodes identical to a single resistor or capacitor.

[0073] The use of the phrase "ground voltage potential" in the foregoing description includes chassis ground, ground wire ground, floating ground, virtual ground, digital ground, universal ground, and / or any other form of ground connection that is applicable or suitable for the teachings of this specification. In this specification, unless otherwise stated, "about," "approximately," or "substantially" preceding a parameter means within a + / -10% range of the parameter. Modifications to the described examples are possible and other examples are possible within the scope of the claims.

Claims

1. A device comprising: a first light source configured to generate a first light signal having a first wavelength; a second light source configured to generate a second light signal having a second wavelength different from the first wavelength; a light detector having a detector output, the light detector being configured to: generating a first detection signal at the detector output in response to the first light signal; and generating a second detection signal at the detector output in response to the second light signal; as well as A processing circuit has a processing input and a processing output, the processing input being coupled to the detector output and the processing circuit being configured to generate a third signal at the processing output representing an air quality measurement in response to the first detection signal and the second detection signal. 2 . The apparatus of claim 1 , wherein the third signal represents at least one of: a particle size or a mass concentration of particles.

3. The apparatus of claim 2, wherein the processing circuit is configured to: determining an intensity ratio between the first light signal and the second light signal received by the light detector based on the first detection signal and the second detection signal; and The particle size is determined based on the intensity ratio.

4. The apparatus of claim 2, wherein the processing circuit is configured to determine the particle size based on at least one of: a polynomial function relating particle size and intensity ratio, or a mapping between particle size and intensity ratio.

5. The apparatus of claim 2, wherein the processing circuit is configured to determine the mass concentration based on the particle size.

6. The apparatus of claim 2, wherein the processing circuit is configured to: determining a received intensity of at least one of the first optical signal or the second optical signal at the optical detector based on at least one of the first detection signal or the second detection signal; determining an expected single particle scattering intensity of the at least one of the first light signal or the second light signal based on the particle size; determining a particle concentration based on a ratio between the received intensity and the expected single particle scattered intensity; and The mass concentration is determined based on the particle concentration.

7. The apparatus of claim 1, wherein the first wavelength is in the infrared spectral region and the second wavelength is in the blue spectral region.

8. The apparatus of claim 1, wherein the first light source is oriented to generate the first light signal at a forward backscatter angle in the range of 50 to 60 degrees, and the second light source is oriented to generate the second light signal at a backward backscatter angle in the range of 145 to 155 degrees.

9. An apparatus according to claim 1, wherein the processing circuit comprises a microcontroller unit (MCU), the MCU comprising a controller input and a controller output, the controller input being coupled to the processing input, and the controller output being coupled to the processing output, and wherein the MCU is configured to: receive the first detection signal and the second detection signal at the controller input; and provide the third signal representing the air quality measurement result at the controller output.

10. A device comprising: A processing circuit having a processing input and a processing output and configured to: receiving at the processing input a first detection signal indicative of detection of a first optical signal having a first wavelength; receiving at the processing input a second detection signal indicative of detection of a second optical signal having a second wavelength; and A third signal representative of an air quality measurement is generated at the processing output in response to the first detection signal and the second detection signal.

11. The apparatus of claim 10, wherein the third signal represents at least one of: a particle size or a mass concentration of particles.

12. The apparatus of claim 11, wherein the processing circuit is configured to: determining an intensity ratio between the first light signal and the second light signal based on the first detection signal and the second detection signal; determining the particle size based on the intensity ratio; and The mass concentration is determined based on the particle size.

13. The apparatus of claim 11, wherein the processing circuit is configured to determine the particle size based on at least one of: a polynomial function relating particle size and intensity ratio, or a mapping between particle size and intensity ratio.

14. The apparatus of claim 11, wherein the processing circuit is configured to: determining a received intensity of at least one of the first optical signal or the second optical signal based on at least one of the first detection signal or the second detection signal; determining an expected single particle scattering intensity of the at least one of the first light signal or the second light signal based on the particle size; determining a particle concentration based on a ratio between the received intensity and the expected single particle scattered intensity; and The mass concentration is determined based on the particle concentration.

15. A method comprising: emitting a first optical signal having a first wavelength using a first light source; emitting, with a second light source, a second optical signal having a second wavelength different from the first wavelength; generating a first detection signal by a light detector in response to the first light signal; generating a second detection signal by the light detector in response to the second light signal; as well as A third signal representing an air quality measurement result is generated by the processing circuit in response to the first detection signal and the second detection signal.

16. The method of claim 15, wherein the third signal represents at least one of: a particle size or a mass concentration of particles.

17. The method according to claim 16, further comprising: determining an intensity ratio between the first light signal and the second light signal based on the first detection signal and the second detection signal; determining the particle size based on the intensity ratio; as well as The mass concentration is determined based on the particle size.

18. The method of claim 16, further comprising determining the particle size based on at least one of: a polynomial function relating particle size to intensity ratio, or a mapping between particle size and intensity ratio.

19. The method of claim 16, further comprising: determining a received intensity of at least one of the first optical signal or the second optical signal based on at least one of the first detection signal or the second detection signal; determining an expected single particle scattering intensity of the at least one of the first light signal or the second light signal based on the particle size; determining a particle concentration based on a ratio between the received intensity and the expected single particle scattered intensity; and The mass concentration is determined based on the particle concentration.

20. A non-transitory computer-readable medium storing instructions that, when executed by a processor, cause the processor to: receiving a first detection signal, the first detection signal indicating detection of a first optical signal having a first wavelength; receiving a second detection signal indicating detection of a second optical signal having a second wavelength; and A third signal representing an air quality measurement is generated in response to the first detection signal and the second detection signal.

21. The non-transitory computer-readable medium of claim 20, wherein the third signal represents at least one of: a particle size or a mass concentration of particles.

22. The non-transitory computer-readable medium of claim 21, wherein the instructions cause the processor to: determining an intensity ratio between the first light signal and the second light signal based on the first detection signal and the second detection signal; determining the particle size based on the intensity ratio; and The mass concentration is determined based on the particle size.

23. The non-transitory computer-readable medium of claim 21, wherein the instructions cause the processor to determine the particle size based on at least one of: a polynomial function relating particle size and intensity ratio, or a mapping between particle size and intensity ratio.

24. The non-transitory computer-readable medium of claim 21, wherein the instructions cause the processor to: determining a received intensity of at least one of the first optical signal or the second optical signal based on at least one of the first detection signal or the second detection signal; determining an expected single particle scattering intensity of the at least one of the first light signal or the second light signal based on the particle size; determining a particle concentration based on a ratio between the received intensity and the expected single particle scattered intensity; and The mass concentration is determined based on the particle concentration.

Images