Self-calibrating fire sensing device

Abstract

The present application relates to "Self-calibrating fire sensing device". A self-calibrating fire sensing device is disclosed, comprising: an emitter light emitting diode (LED) (105-1, 205-1, 205) configured to emit light; a first photodiode (106-1, 206-1, 306) configured to detect a LED emission level of the light; a second photodiode (106-2, 206-2, 306) configured to detect a scattering level of the light; and a controller (122) configured to re-calibrate a gain used by the second photodiode (106-2, 206-2, 306) to detect the scattering level in response to detecting the LED emission level of the light.

Description

[0001] This application is a continuation of the invention patent application with the national application number 202110753096.9, the application date of which is July 2, 2021, and the invention name of which is “Self-calibrating fire sensing device”. TECHNICAL FIELD

[0002] The present disclosure generally relates to devices, methods, and systems for self-calibrating optical smoke chambers within fire sensing devices. BACKGROUND

[0003] Large facilities (e.g., buildings), such as commercial facilities, office buildings, hospitals, etc., can have fire alarm systems that can be triggered during an emergency (e.g., a fire) to alert occupants to evacuate. For example, a fire alarm system can include a fire control panel and a plurality of fire sensing devices (e.g., smoke detectors) that are spread throughout the facility (e.g., on different floors and / or in different rooms of the facility) that can sense a fire occurring in the facility and provide notification of the fire to the occupants of the facility via an alarm. The fire sensing devices can include one or more sensors. The one or more sensors can include, for example, optical smoke sensors, heat sensors, gas sensors, and / or flame sensors.

[0004] Over time, components of the fire sensing devices can deteriorate and / or become contaminated and not within their initial operational specifications. For example, the output of light emitting diodes (LEDs) used in the optical scattering chamber of a smoke detector can deteriorate over time and / or usage. These deteriorated components can hinder the fire sensing device from detecting a fire at an early enough stage. As a result, industry guidelines require periodic sensitivity testing (e.g., alarm threshold verification testing) of the smoke detectors. However, due to access issues and the need to deploy expert equipment to perform the testing, it can not be practical to conduct accurate sensitivity testing in the field. As a result, basic function testing is often substituted for accurate sensitivity testing, which is misleading as it does not accurately describe the sensitivity of the smoke detector being verified.

[0005] In some countries, due to the fact that the accurate sensitivity of the smoke detector can not be determined and / or testing is not performed, the device needs to be replaced after a certain period of time. For example, in Germany, even the most advanced smoke detector must be replaced after 8 years, even if the device is still working accurately. This can create unnecessary waste, which has a negative impact on the environment. BRIEF DESCRIPTION OF DRAWINGS

[0006] Figure 1 A block diagram of a self-calibrating fire sensing device according to embodiments of the present disclosure is shown.

[0007] Figure 2AAn example of a self-calibrating fire sensing device is shown in accordance with embodiments of the present disclosure.

[0008] Figure 2B An example of a self-calibrating fire sensing device is shown in accordance with embodiments of the present disclosure.

[0009] Figure 3 Circuitry of a self-calibrating fire sensing device is shown in accordance with embodiments of the present disclosure.

[0010] Figure 4 A block diagram of a system including a self-calibrating fire sensing device is shown in accordance with embodiments of the present disclosure. DETAILED DESCRIPTION

[0011] Devices, methods, and systems for a self-calibrating optical smoke chamber within a fire sensing device are described herein. One device includes a first emitter LED configured to emit a first light, a second emitter LED configured to emit a second light, a first photodiode coaxial with the first emitter LED, where the first photodiode is configured to select a first gain or a second gain of a first variable gain amplifier and detect a LED emission level of the first light in response to selecting the first gain and a scattering level of the second light in response to selecting the second gain, and a second photodiode coaxial with the second emitter LED, where the second photodiode is configured to select a third gain or a fourth gain of a second variable gain amplifier and detect a LED emission level of the second light in response to selecting the third gain and a scattering level of the first light in response to selecting the fourth gain, and a controller configured to recalibrate the fourth gain in response to the detected LED emission level of the first light and / or recalibrate the second gain in response to the detected LED emission level of the second light. The controller can use a software gain function to calibrate and / or recalibrate the gains. In some examples, the controller can be configured to use the software gain function to recalibrate the second gain in response to the detected LED emission level of the first light, recalibrate the fourth gain in response to the detected LED emission level of the second light, recalibrate the first gain in response to the detected LED emission level of the second light, and / or recalibrate the third gain in response to the detected LED emission level of the first light.

[0012] In previous smoke detectors, a maintenance engineer would have to manually test the sensitivity of the smoke detector and replace the smoke detector if the smoke sensitivity was incorrect, but unlike previous smoke detectors, the smoke detector according to the present disclosure can test, calibrate, and / or recalibrate itself. Thus, the fire sensing device according to the present disclosure can take significantly less maintenance time to test, and can test, calibrate, and / or recalibrate continuously and / or on demand, and can more accurately determine the ability of the fire sensing device to detect an actual fire. Thus, the self-calibrating fire sensing device can have an extended useful life and be replaced less often, resulting in a positive environmental impact.

[0013] In the following DETAILED DESCRIPTION, reference is made to the accompanying drawings, which form a part hereof. The drawings show, by way of illustration, a manner in which one or more embodiments of the present disclosure can be practiced.

[0014] These embodiments are described in sufficient detail to enable those skilled in the art to practice one or more embodiments of the present disclosure. It is to be understood that other embodiments can be utilized and that mechanical, electrical, and / or process changes can be made without departing from the scope of the present disclosure.

[0015] It is to be understood that the elements shown in the embodiments herein can be added to, swapped with, combined with, and / or eliminated from, to provide a number of further embodiments of the present disclosure. The proportions and relative dimensions of the elements provided in the drawings are intended to illustrate embodiments of the present disclosure and should not be taken in a limiting sense.

[0016] The drawings herein follow a numbering convention in which the first digit or digits correspond to the drawing figure number and the remaining digits, if any, correspond to the number of the element or component in the drawing figure. Similar elements or components between different drawings can be indicated by the use of similar digits. For example, 104 can reference element "04" in FIG. 1, and a similar element can be referenced as 204 in FIG. 2. Figure 1 Figure 2A

[0017] As used herein, "one" or "a" thing can refer to one or more such things, while "a plurality of" things can refer to more than one such thing. For example, "a plurality of components" can refer to one or more components, while "plurality of components" can refer to more than one component.

[0018] Figure 1 A block diagram of a self-calibrating fire sensing device 100 according to embodiments of the present disclosure is shown. The fire sensing device 100 includes a controller 122 and an optical scattering chamber 104.

[0019] ​​The controller 122 can include a memory 124, a processor 126, and circuitry 128. The memory 124 can be any type of storage medium that is accessible by the processor 126 to perform the various examples of the present disclosure. For example, the memory 124 can be a non-transitory computer-readable medium having computer-readable instructions (e.g., computer program instructions) stored thereon that the processor 126 is capable of executing to test, calibrate, and / or recalibrate the fire sensing device 100 according to the present disclosure. For example, the processor 126 can execute executable instructions stored in the memory 124 to emit the first light and the second light, select the first gain or the second gain, detect the LED emission level of the first light in response to selecting the first gain, and detect the scattering of the second light in response to selecting the second gain, recalibrate (e.g., increase or decrease) the second gain in response to the detected LED emission level of the second light. In some examples, the memory 124 can store the detected LED emission level of the first light and / or the detected scattering of the second light.

[0020] The optical scattering chamber 104 can include emitter LEDs 105-1 and 105-2 and photodiodes 106-1 and 106-2 to measure the aerosol density level by detecting scattering. The scattering can be the reflection, refraction, and / or diffraction of light from the emitter LEDs 105-1 and / or 105-2 off of particles and can be received by the photodiodes 106-1 and / or 106-2. The amount of light received by the photodiodes 106-1 and / or 106-2 can be used to determine the aerosol density level.

[0021] The emitter LED 105-1 can emit the first light, and the emitter LED 105-2 can emit the second light. As shown in FIG. 1, the photodiode 106-1 can be coaxial with the emitter LED 105-1 (e.g., directly across from the emitter LED 105-1) such that the photodiode 106-1 directly receives the first light and receives the scattering of the second light. The photodiode 106-2 can be coaxial with the emitter LED 105-2 such that the photodiode 106-2 directly receives the second light and receives the scattering of the first light. The photodiode 106-1 can detect the LED emission level of the first light and detect the scattering level of the second light. The photodiode 106-2 can detect the LED emission level of the second light and detect the scattering level of the first light. Figure 1

[0022] ​Due to, for example, manufacturing variations, the emitter LEDs 105-1 and 105-2 (which can be collectively referred to herein as the emitter LEDs 105) can have varying LED emission levels. Accordingly, the emitter LEDs 105 can need to be calibrated prior to use. The fire sensing device 100 can calibrate the emitter LEDs 105 by injecting a known aerosol density level into the optical scattering chamber 104. The photodiodes 106-1 and 106-2 (which can be collectively referred to herein as the photodiodes 106) can detect the scattering level, and the controller 122 can compare the detected scattering level to the known aerosol density level to calculate the sensitivity of each scattering path. For example, the emitter LED 105-1 can emit a first light, and the photodiode 106-2 can detect a scattering level of the first light scattering from particles of the known aerosol density level. The controller 122 can calculate the sensitivity of the scattering path from the emitter LED 105-1 to the photodiode 106-2 based on the detected scattering level and the known aerosol density level. The controller 122 can similarly calculate and store the sensitivity of the scattering path from the emitter LED 105-2 to the photodiode 106-1. The sensitivity of each scattering path can be stored in the memory 124.

[0023] In some examples, the sensitivity can be improved by recalibrating a gain used to amplify an input signal of the photodiode 106. For example, as the first light from the emitter LED 105-1 weakens over time, the amplifier gain can be increased to increase the voltage and / or current of the input signal of the photodiode 106-2 to detect the first light from the emitter LED 105-1. The gain of the amplifier can be recalibrated (e.g., modified) in response to the detected scattering level and / or the LED emission level. For example, the gain of the amplifier can be recalibrated in response to the calculated sensitivity of the scattering path being less than a threshold sensitivity.

[0024] The photodiodes 106 can be in variable gain amplifiers (e.g., in Figure 3The gain selection circuit 320 can select between a plurality of gains (e.g., of the operational amplifiers 325-1 and 325-2, further described below). In some examples, detecting the LED emission level of an on-axis emitter LED 105 can require less gain than detecting the scatter of an off-axis emitter LED 105 because the light from an on-axis emitter LED 105 is direct light (e.g., higher intensity) and the light from an off-axis emitter LED 105 is indirect light (e.g., lower intensity). For example, the photodiode 106-1 can select a first gain to detect the LED emission level of the first light from the emitter LED 105-1 or a second gain to detect the scatter level of the second light from the emitter LED 105-2. Similarly, the photodiode 106-2 can select a third gain to detect the LED emission level of the second light from the emitter LED 105-2 or a fourth gain to detect the scatter level of the first light from the emitter LED 105-1.

[0025] In various embodiments, a fault (e.g., an error) can be triggered in response to the detected LED emission level or the detected scatter level. For example, the controller 122 can compare the detected LED emission level to a threshold LED emission level and trigger a fault in response to the detected LED emission level being below the threshold LED emission level. Another example can include the controller 122 comparing the detected LED emission level to a previously detected LED emission level and triggering a fault in response to the detected LED emission level being less than the previously detected LED emission level.

[0026] The various amplifier gains can be calibrated by storing the initially detected LED emission level and the various amplifier gains in the memory 124. Over time, the LED emission level of the emitter LED 105 can decrease, resulting in less light received by the photodiode 106, which can cause the fire sensing device 100 to malfunction.

[0027] The amplifier gain used by the photodiode 106 to detect the scatter level can be recalibrated as the emitter LED degrades over time. The controller 122 can recalibrate the gain in response to the detected LED emission level and / or the detected scatter level. For example, the controller 122 can initiate recalibration of the gain in response to comparing the detected LED emission level to a threshold LED emission level and determining that the detected LED emission level is below the threshold LED emission level. In some examples, the controller 122 can recalibrate the gain in response to determining that a difference between the detected LED emission level and the initially detected LED emission level is greater than a threshold and / or in response to determining that the detected LED emission level is less than a previously detected LED emission level.

[0028] Figure 2A An example of a self-calibrating fire sensing device 200 is shown in accordance with an embodiment of the present disclosure. The fire sensing device 200 can be, but is not limited to, a fire detector and / or a smoke detector of a fire control system, and can be, for example, the fire sensing device 100 previously described in conjunction with Figure 1 Figure 2A The self-calibrating fire sensing device 200 shown in

[0029] The fire sensing device 200 can sense a fire occurring in a facility and trigger a fire response to provide notification of the fire to a user of the facility. The fire response can include, for example, a visual and / or audio alarm. The fire response can also notify emergency services (e.g., a fire department, a police department, etc.). In some examples, multiple fire sensing devices can be spread throughout a facility (e.g., on different floors and / or in different rooms of the facility).

[0030] The fire sensing device 200 can automatically or on command perform one or more tests contained within the fire sensing device 200. The one or more tests can determine whether the fire sensing device 200 is functioning properly, whether maintenance is required, and / or whether recalibration is required.

[0031] As shown in Figure 2A , the fire sensing device 200 can include an optical scattering chamber 204 that can correspond to the optical scattering chamber 104, the emitter LEDs 105-1 and 105-2, and the photodiodes 106-1 and 106-2 of Figure 1 , respectively.

[0032] As previously described, the detected LED emission level and / or scattering level can be used to determine whether the fire sensing device 200 requires maintenance and / or recalibration. For example, the fire sensing device 200 can be determined to require maintenance and / or recalibration in response to the calculated sensitivity being outside of the sensitivity range.

[0033] In some examples, the fire sensing device 200 can generate a message if the device requires maintenance (e.g., if the sensitivity is outside of the sensitivity range). The fire sensing device 200 can send the message to, for example, a monitoring device (e.g., the monitoring device 401 in Figure 4 ). As a further example, the fire sensing device 200 can include a user interface that can display the message.

[0034] Figure 2A ​The fire sensing device 200 shows emitter LED 205-1, emitter LED 205-2, photodiode 206-1, and photodiode 206-2. Emitter LED 205-1 can emit a first light, and emitter LED 205-2 can emit a second light. In some examples, the first light can have a first wavelength, and the second light can have a second wavelength. For example, emitter LED 205-1 can be an infrared (IR) LED having a first wavelength, and emitter LED 205-2 can be a blue LED having a second wavelength. Having two or more different wavelengths can help the fire sensing device 200 detect various types of smoke. For example, the first wavelength can better detect a flame including a backside aerosol, and the second wavelength can better detect water vapor including a white non-igniting aerosol. In some examples, a ratio of the first wavelength to the second wavelength can be used to indicate a type of smoke.

[0035] As shown in FIG. 2, the photodiode 206-1 can be coaxial with the emitter LED 205-1 such that the photodiode 206-1 directly receives the first light and receives scattering of the second light, and the photodiode 206-2 can be coaxial with the emitter LED 205-2 such that the photodiode 206-2 directly receives the second light and receives scattering of the first light. The photodiode 206-1 can detect a LED emission level of the first light and detect a scattering level of the second light. The photodiode 206-2 can detect a LED emission level of the second light and detect a scattering level of the first light. Figure 2A As shown in FIG. 2, the photodiode 206-1 can be coaxial with the emitter LED 205-1 such that the photodiode 206-1 directly receives the first light and receives scattering of the second light, and the photodiode 206-2 can be coaxial with the emitter LED 205-2 such that the photodiode 206-2 directly receives the second light and receives scattering of the first light. The photodiode 206-1 can detect a LED emission level of the first light and detect a scattering level of the second light. The photodiode 206-2 can detect a LED emission level of the second light and detect a scattering level of the first light.

[0036] Due to, for example, manufacturing variations, the emitter LEDs 205-1 and 205-2 (which can be collectively referred to herein as emitter LEDs 205) can have varying LED emission levels. Thus, the emitter LEDs 205 can need to be calibrated prior to use. As described above, the fire sensing device 200 can calibrate the emitter LEDs 205 by receiving a known aerosol density level. The photodiodes 206-1 and 206-2 (which can be collectively referred to herein as photodiodes 206) can detect a scattering level, which can be compared to the known aerosol density level to calculate a sensitivity for each scattering path.

[0037] In some examples, the sensitivity accuracy can be improved by modifying a gain used to amplify an input signal of the photodiodes 206. The gain of the photodiodes 206 can be recalibrated in response to the LED emission levels, as previously described herein.

[0038] The photodiodes 206 can be at a variable gain amplifier (e.g., at a variable gain amplifier 208 in FIG. 2). The variable gain amplifier 208 can be configured to amplify the input signal of the photodiodes 206. The variable gain amplifier 208 can be configured to modify the gain of the input signal of the photodiodes 206 in response to the LED emission levels, as previously described herein. Figure 3The selection between the multiple gains (of the operational amplifiers 325-1 and 325-2, further described below) can be based on whether the photodiode 206 is detecting LED emission levels or scatter levels. In some examples, detecting LED emission levels of an on-axis emitter LED 205 can require less gain than detecting scatter of an off-axis emitter LED 205 because the light from the on-axis emitter LED 205 is direct light (e.g., higher intensity) and the light from the off-axis emitter LED 205 is indirect light (e.g., lower intensity). For example, the photodiode 206-1 can select a first gain to detect LED emission levels of the first light from the emitter LED 205-1 or a second gain to detect scatter levels of the second light from the emitter LED 205-2. Similarly, the photodiode 206-2 can select a third gain to detect LED emission levels of the second light from the emitter LED 205-2 or a fourth gain to detect scatter levels of the first light from the emitter LED 205-1.

[0039] Figure 2B An example of a self-calibrating fire sensing device 200 is shown in accordance with an embodiment of the disclosure. Figure 2B The fire sensing device 200 can be a dual optical smoke chamber that uses two different scatter angles (e.g., forward scatter and backscatter) and can include an emitter LED 205, a photodiode 206-1, a photodiode 206-2, and a photodiode 206-3. The fire sensing device 200 can also include an optical scatter chamber 204, which can correspond to the optical scatter chamber 204 of FIG. 1. Figure 2A The optical scatter chamber 204 of FIG. 1.

[0040] The emitter LED 205 can emit a first light. The photodiode 206-1 can be located on a first axis with the emitter LED 205 such that the photodiode 206-1 receives the first light directly, and the photodiode 206-2 and / or the photodiode 206-3 can be located on a second axis such that the photodiode 206-2 and / or the photodiode 206-3 receive the first light indirectly (e.g., via scatter). In some examples, the second axis can be offset 60 degrees relative to the first axis.

[0041] The photodiode 206-1 can detect LED emission levels of the first light, and the photodiode 206-2 and / or the photodiode 206-3 can detect scatter levels of the first light. The photodiode 206-2 and / or the photodiode 206-3 can be positioned at a particular angle relative to the emitter LED 205-1 to detect various types of smoke. For example, the photodiode 206-2 can be located about 120 degrees relative to the emitter LED 205 and / or the photodiode 206-1 can be located about 60 degrees relative to the emitter LED 205.

[0042] Figure 3 A self-calibrating fire sensing device according to an embodiment of the present disclosure is shown (e.g., combined with...). Figure 1 and Figure 2A The circuit 328 of the fire sensing device 100 and / or 200. For example... Figure 3 As shown, circuit 328 may include components corresponding to... Figure 1 Photodiode 106 and Figure 2A The photodiode 206 in the fire sensing device is a photodiode 306. Each photodiode in the fire sensing device may have a corresponding circuit 328. The circuit 328 may also include one or more configurable impedance networks 310-1, 310-2, a feedback network 312, a reference voltage 321, a ground reference 320-1, 320-2, an input signal 323, an output signal 327, and a control line 329 associated with one or more operational amplifiers 325-1, 325-2 that can act as variable gain amplifiers.

[0043] As previously mentioned, detecting the LED emission level of a coaxial emitter LED will require less gain than detecting the scattering level of an off-axis emitter LED, because the light from the coaxial emitter LED is direct light (e.g., higher intensity), while the light from the off-axis emitter LED is indirect (e.g., scattered) light (e.g., lower intensity). Control line 329 can change the gain of operational amplifiers 325-1 and 325-2 in response to the fire sensing device (e.g., photodiode 306) detecting either the LED emission level or the scattering level. For example, operational amplifier 325-1 can be configured as a transimpedance amplifier (TIA) with variable gain, such that when photodiode 306 detects an input signal 323 that may be a short pulse of light of approximately 100 µS, a proportional photocurrent will follow in photodiode 306. The inverting input of operational amplifier 325-1 can then become less than the reference voltage 321 at the non-inverting input. Operational amplifier 325-1 can increase its output voltage to supply photocurrent via a configurable impedance network 310-1. The output voltage on operational amplifier 325-1 is equal to the product of the photocurrent and the impedance of configurable impedance network 310-1. In other words, control line 329 can change the impedance of configurable impedance network 310-1, thereby changing the photocurrent and voltage gain of operational amplifier 325-1.

[0044] The additional operational amplifier 325-2 can be configured as a non-inverting amplifier to further amplify the output voltage from the TIA operational amplifier 325-1. The gain of operational amplifier 325-2 is determined by the configurable impedance network 310-2, and therefore by control line 329. The output signal 327 from operational amplifier 325-2 can be controlled by a controller (e.g., Figure 1The feedback network 312 can be used to reduce DC offset error and for ambient light compensation.

[0045] Emission light from the emitter LED can decrease over time. The controller can use the control line 329 to select a very low gain, measure the output signal 327 corresponding to the direct output level from the LED, and then recalibrate its software gain associated with the high hardware gain for the scatter level. In this way, changes in the emitter LED emission level can be compensated for by software gain changes by the controller, for example, with 8-bit resolution or 256 possible gain settings.

[0046] Figure 4 A block diagram of a system 420 including a self-calibrating fire sensing device 400 is shown in accordance with an embodiment of the disclosure. The fire sensing device 400 can be, for example, the fire sensing device 100 and / or 200 previously described in connection with Figure 1 , Figure 2A and Figure 2B respectively. The system 420 can also include a monitoring device 401.

[0047] The monitoring device 401 can be, for example, a control panel, a cloud computing device of a fire detection control system, and / or a fire alarm system. The monitoring device 401 can be configured to send commands to and / or receive test, calibration, and / or recalibration results from the fire sensing device 400 via a wired or wireless network. For example, the fire sensing device 400 can transmit (e.g., send) a message to the monitoring device 401 in response to the fire sensing device 400 determining that the fire sensing device 400 needs maintenance and / or needs recalibration. The fire sensing device 400 can also transmit a message in response to calibrating the fire sensing device 400, recalibrating the fire sensing device 400, detecting LED emission levels at the fire sensing device 400, and / or detecting scatter at the fire sensing device 400.

[0048] In various embodiments, the fire sensing device 400 can transmit data to the monitoring device 401. For example, the fire sensing device 400 can emit detected LED emission levels and / or detected scatter levels. In some examples, the monitoring device 401 can receive messages and / or data from a plurality of fire sensing devices similar to the fire sensing device 400.

[0049] The monitoring device 401 can include a controller 432 that includes a memory 434, a processor 436, and a user interface 438. The memory 434 can be any type of storage medium that is accessible by the processor 436 to perform various examples of the present disclosure. For example, the memory 434 can be a non-transitory computer-readable medium having computer-readable instructions (e.g., computer program instructions) stored thereon that the processor 436 can execute in accordance with the present disclosure. For example, the processor 436 can execute executable instructions stored in the memory 434 to receive a detected LED emission level, receive a detected scatter level, compare the detected LED emission level to a LED emission level specification range, compare the detected scatter level to a scatter specification range, transmit an error notification in response to the detected LED emission level being outside the LED emission level specification range, transmit an error notification in response to the detected scatter level being outside the scatter specification range, determine a gain setting, and / or transmit a command to the fire sensing device 400. In some examples, the memory 434 can store a previously detected LED emission level, a previously detected scatter level, a detected LED emission level, a detected scatter level, a LED emission level specification range, and / or a scatter specification range.

[0050] In various embodiments, the controller 432 can send a command to the fire sensing device 400. The command can include a gain setting for a photodiode of the fire sensing device 400. The controller 432 can determine the gain setting based on a detected LED emission level and / or a detected scatter level received from the fire sensing device 400. The controller 432 can compare the detected LED emission level to a LED emission level specification range, a previously detected LED emission level, and / or a detected LED emission level of a different fire sensing device, and recalibrate one or more gains of one or more amplifiers based on the comparison. In some examples, the controller 432 can compare the detected scatter level to a scatter level range, a previously detected scatter level, and / or a detected scatter level of a different fire sensing device. The fire sensing device 400 can recalibrate one or more gains of one or more photodiodes based on the comparison.

[0051] In various embodiments, the monitoring device 401 can include a user interface 438. The user interface 438 can be a GUI that can provide information to and / or receive information from a user and / or the fire sensing device 400. The user interface 438 can display messages and / or data received from the fire sensing device 400. For example, the user interface 438 can display an error notification in response to the detected LED emission level being outside the LED emission level specification range and / or the detected scatter level being outside the scatter specification range.

[0052] The network described herein can be a network relationship through which the fire sensing device 400 and the monitoring device 401 communicate with each other. Examples of such network relationships can include a distributed computing environment (e.g., a cloud computing environment), a wide area network (WAN) such as the Internet, a local area network (LAN), a personal area network (PAN), a campus area network (CAN), or a metropolitan area network (MAN), among other types of network relationships. For example, the network can include a plurality of servers that receive information from and send information to the fire sensing device 400 and the monitoring device 401 via a wired or wireless network.

[0053] As used herein, a “network” can provide a communication system that links two or more computers and / or peripheral devices either directly or indirectly and allows the monitoring device 401 to access data and / or resources on the fire sensing device 400 and vice versa. The network can allow users to share resources on their own systems with other network users and access information on systems located in a central location or on systems located at remote locations. For example, the network can connect multiple computing devices together to form a distributed control network (e.g., a cloud).

[0054] The network can provide connectivity to the Internet and / or to networks of other entities (e.g., organizations, institutions, etc.). A user can interact with a network-enabled software application to issue network requests, such as to retrieve data. The application can also communicate with network management software, which can interact with network hardware to transmit information between devices on the network.

[0055] While specific embodiments have been illustrated and described herein, it will be appreciated that any arrangement devised to achieve the same technical result can be substituted for the specific embodiments shown. This disclosure is intended to cover any and all modifications and variations coming within the scope of various embodiments of the present disclosure.

[0056] It should be understood that the above description is given by way of illustration and not limitation. Combinations of the above embodiments, and other embodiments, not specifically described herein, will be apparent to those of ordinary skill in the art upon reading the above description.

[0057] The scope of various embodiments of the present disclosure includes any other application of the structures and methods described above. Accordingly, the scope of various embodiments of the present disclosure should be determined by reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0058] In the specific embodiments described above, for the purpose of simplifying the present disclosure, various features that are placed into combination in the example embodiments shown in the drawings. The method of this disclosure should not be interpreted as reflecting an intention that embodiments of the present disclosure require more features than are explicitly recited in each claim.

[0059] In contrast, the inventive subject matter is directed to less than all of the features of the single disclosed embodiment, as reflected in the claims below. Thus, the claims below are hereby incorporated into the DETAILED DESCRIPTION, where each claim stands on its own as a separate embodiment.

Claims

1. A self-calibrating fire sensing device (100, 200, 400), comprising: a transmitter light emitting diode, LED (105-1, 205-1, 205), configured to emit light; a first photodiode (106-1, 206-1, 306) configured to detect an LED emission level of the light; a second photodiode (106-2, 206-2, 306) configured to detect a scattering level of the light; a controller (122) configured to recalibrate a gain used by the second photodiode (106-2, 206-2, 306) to detect the scattering level in response to detecting the LED emission level of light; and a third photodiode (206-3, 306) coaxial with the second photodiode (106-2, 206-2, 306), wherein the third photodiode (206-3, 306) is configured to detect an additional scattering level of the light.

2. The device of claim 1, wherein the first photodiode (106-1, 206-1, 306) is coaxial with the transmitter LED (105-1, 205-1, 205).

3. The device of claim 1, wherein: the second photodiode (106-2, 206-2, 306) is configured to detect a first type of smoke; and the third photodiode (206-3, 306) is configured to detect a second type of smoke.

4. The apparatus of claim 1, wherein, the third photodiode (206-3, 306) is positioned 60 degrees relative to the transmitter LED (105-1, 205-1, 205).

5. The apparatus of claim 1, wherein, the second photodiode (106-2, 206-2, 306) is positioned 120 degrees relative to the transmitter LED (105-1, 205-1, 205).

6. The device of claim 1, wherein the controller (122) is configured to trigger a fault in response to detecting the LED emission level of light or detecting the scattering level of light.

7. The device of claim 6, wherein the controller (122) is configured to: compare the detected LED emission level of light to a threshold LED emission level; and trigger the fault in response to detecting that the LED emission level of light is below the threshold LED emission level.

8. The device of claim 6, wherein the controller (122) is configured to: compare the detected LED emission level of light to a previously detected LED emission level; and trigger the fault in response to detecting that the LED emission level of light is less than the previously detected LED emission level.

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