Patent Application
20230230468
The present disclosure relates generally to fire detection systems and methods, and more particularly, to smoke detectors.
The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.
An example implementation includes a smoke detector comprising a smoke chamber; a light emitting diode (LED) configured to generate light that is directed into the smoke chamber; a photodetector configured to detect whether at least a threshold amount of the light is scattered by smoke particles when smoke is present in the smoke chamber; and one or more self-testing components configured to re-direct at least a portion of the light from the LED toward the photodetector for self-testing the LED and the photodetector.
Another example implementation includes a smoke detector comprising a smoke chamber; a light emitting diode (LED) configured to generate light that is directed into the smoke chamber; a photodetector configured to detect whether at least a threshold amount of the light is scattered by smoke particles when smoke is present in the smoke chamber; and one or more self-testing components configured to re-direct at least a portion of the light from the LED toward the photodetector for self-testing the LED and the photodetector.
A further example implementation includes a method comprising controlling one or more one or more self-testing components of a smoke detector to re-direct at least a portion of light from a light emitting diode (LED) toward a photodetector, wherein the LED is configured to generate the light that is directed into a smoke chamber of the smoke detector, wherein the photodetector is configured to detect whether at least a threshold amount of the light is scattered by smoke particles when smoke is present in the smoke chamber; and determining whether the photodetector causes an alarm trigger in response to the controlling.
To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed, and this description is intended to include all such aspects and their equivalents.
The disclosed aspects will hereinafter be described in conjunction with the appended drawings, provided to illustrate and not to limit the disclosed aspects, wherein like designations denote like elements, and in which:
The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well known components may be shown in block diagram form in order to avoid obscuring such concepts.
Some present aspects implement self-test functionality in a smoke detector, where the self-test functionality validates at least a portion of an optical path that is used to detect the presence of smoke in a smoke chamber of the smoke detector. Some alternative or additional aspects implement further self-test functionality for detecting a masking of the smoke detector (which may be due to dust, bugs, malicious attempts to disable the smoke detector, etc.), where the self-test functionality validates an optical path from outside the smoke chamber into the smoke chamber.
Turning now to the figures, example aspects are depicted with reference to one or more components described herein, where components in dashed lines may be optional.
Referring to
Referring to
Some self-test processes for smoke detectors require a person to temporarily introduce smoke into the environment around the smoke detector and/or into the smoke chamber to ensure that the smoke detector triggers an alarm. This is typically done with artificial smoke output by an aerosol can. However, these self-test processes are cumbersome and time consuming, in particular, in large installations with many smoke detectors.
Some self-test systems configure a small amount of paraffin or other suitable substance within the smoke detector such that the paraffin may be heated with an electrical element to generate smoke in order to test the smoke detector. However, the evaporated paraffin may also contaminate the smoke detector. Further, heating the paraffin requires a significant amount of power for the heating element, which is undesirable, in particular, for battery-powered residential smoke detectors which may be required to have a sealed 10-year-life battery.
In contrast, some present aspects provide one or more self-testing components that re-direct the light from the LED 104 such that the re-directed light strikes the photodetector 108. Accordingly, these aspects provide a low-cost and/or low-power self-test mechanism for testing the LED 104 and the photodetector 108. Some alternative or additional aspects provide a further self-test mechanism that directs light from a light source outside the smoke chamber 102 such that the light strikes the photodetector 108. Accordingly, these alternative or additional aspects may test whether the screens around, and/or pathways into, the smoke chamber 102 are blocked with dust, insects, etc., and/or whether the smoke detector 100 has been tampered with. The efficient, low-cost, and low-power self-test mechanisms according to the present aspects may be incorporated into any type of smoke detector, and may be especially beneficial for use with a battery-powered and/or a residential smoke detector, such as a smoke detector with a sealed 10-year-life battery.
Referring to
In some non-limiting aspects, the light scattering surface 114 may be covered with a paint having the necessary properties to scatter incident light in multiple directions to be easily visible. In some other non-limiting aspects, the light scattering surface 114 may include an injection-molded plastic surface that is textured to achieve the desired scattering. It should be understood, however, that any type of surface with sufficient light scattering properties may be used.
In some aspects, since the amount of light reflected by smoke particles in the smoke chamber 102 is a fraction of the light emitted from the LED 104, the properties of the light scattering surface 114 may be tuned depending on how much light is to be deflected in different angles, so as to more closely simulate the presence of smoke. For example, the angle of deflection caused by the light scattering surface 114 may be tuned to simulate a particular amount of smoke, e.g., a small amount of smoke, a threshold trigger level of smoke, heavy smoke, etc. For example, the deflection properties of the light scattering surface 114 may be tuned so that the photodetector 108 causes an alarm trigger as if a threshold amount of smoke has entered the smoke chamber 102, and if the alarm is not triggered, the self-test has failed, indicating that, for example, the detector is dirty or the light source is wearing out, etc. Alternatively, or additionally, the light scattering surface 114 may have different areas with different light scattering properties, and the controllable mirror 112 may be controlled to reflect light onto a particular area to test the response of the smoke detector 100 to different simulated levels of smoke in the smoke chamber 102.
Alternatively, or additionally, since the amount of light reflected by smoke particles in the smoke chamber 102 is a fraction of the light emitted from the LED 104, the drive current to the LED 104 during self-testing may be controlled (e.g., low intensity, medium intensity, high intensity) to simulate the different amounts of light scattered by various levels of smoke in the smoke chamber 102.
Referring to
Alternatively, instead of or in addition to controlling the reflectivity of the self-test mirror 120 by a shutter, the reflectivity of the light scattering surface 114 may be controlled by a shutter, which may be placed adjacent to the surface of the self-test mirror 120 and/or the light scattering surface, and/or anywhere in the path between the light source (e.g., the LED 104) and the self-test mirror 120 and the light scattering surface 114.
For example, referring to
Referring to
Referring to
Alternatively, instead of or in addition to controlling the reflectivity of the self-test mirror 120 by a shutter, the reflectivity of the surface-mount mirror 121 and/or the light scattering surface 114 may be controlled by a shutter, as described above and below.
For example, referring to
In another example additional and/or alternative aspect, referring to
In some further alternative aspects, the smoke detector 100 may not include the light scattering surface 114, or the smoke detector 100 may not include the controllable mirror 112 and the light scattering surface 114 may be controllable.
For example, in one non-limiting example alternative or additional aspect, referring to
In another non-limiting alternative or additional aspect, for example, referring to
In some other alternative and/or additional aspects, the smoke detector 100 may not include any additional components for self-testing, and instead the mirror 106 and/or the light scattering surface 114 may be controllable to reflect the received light directly toward the photodetector 108 for self-testing the smoke detector 100.
For example, referring to
In some alternative and/or additional non-limiting aspects, a self-test light source may be configured in the smoke chamber 102 to light the photodetector 108 for testing the photodetector 108. In these aspects, the LED 104 may be separately tested, for example, by measuring the current running through the LED 104 and comparing the measured current to a threshold current to determine whether the LED 104 is operating properly.
Some alternative and/or additional aspects implement one or more masking self-test components that validate an optical path from outside the smoke chamber 102 into the smoke chamber 102 in order to detect whether the smoke detector 100 has been masked (e.g., due to dust, bugs, malicious attempts to disable the smoke detector, etc.). Detection of masking is desirable because such masking, e.g., blocking of the flow of smoke into the smoke chamber 102, may render the smoke detector 100 ineffective in detecting smoke.
Referring to
The one or more external LEDs 116 are positioned such that, in absence of any masking of the smoke detector 100, at least a portion of the light from the external LEDs 116 passes through the screens 118 and strikes the light scattering surface 114 configured at the top of the smoke chamber 102 and facing the photodetector 108. The light scattering surface 114 then scatters the light such that at least a portion of the scattered light strikes the photodetector 108, thus indicating that no masking has occurred. However, when the smoke detector 100 is masked (e.g., when the smoke detector 100 is covered/painted on, the environment is dusty, spider webs are present within the smoke chamber 102 and/or on the screens 118, etc.), the masking blocks the light from the one or more external LEDs 116, and the light from the one or more external LEDs 116 does not reach the light scattering surface 114.
In some non-limiting aspects, multiple external LEDs 116 may be configured around the perimeter of the smoke chamber 102 to self-test the smoke detector 100 from multiple angles.
In some non-limiting aspects, the one or more external LEDs 116 may be made with an injection-molded plastic light pipe or prism. In some non-limiting aspects, the external LEDs 116 may be surface-mounted on the PCB substrate 101.
Referring to
Referring to
In some non-limiting aspects, the smoke detector 100 may include masking self-test functionality (e.g., as described with reference to
For example, when self-testing the LED 104 and the photodetector 108 (e.g., as described with reference to
Similarly, when performing the masking self-test, the self-testing of the LED 104 and the photodetector 108 may be disabled so that any light received by the photodetector 108 is re-directed only from outside the smoke detector 100. The disabling may be performed, for example, by turning off the LED 104, configuring the controllable mirror 112 in the normal state, closing the shutter 115 that covers the controllable mirror 112, closing the shutter 115 that covers the self-test mirror 120, configuring the mirror 106 in the normal state, etc.
In some further alternative or additional aspects, multiple external LEDs 116 may be focused and aligned to generate interference patterns that create scattering so that the scattered light is detectable by the photodetector 108. In some non-limiting aspects, depending on characteristics of the photodetector 108, different wavelengths of light may be selected for the external LEDs 116.
In some non-limiting example aspects, the controllable mirror 112 and/or the external controllable mirror 130 may be configured using technology similar to a flip-dot unit. Specifically, for example, a mirror may be configured on a disk that includes a magnet and is freely rotatable between two opposite poles of a U-shaped ferromagnetic core. The mirror is initially in the normal state when the coil is not magnetized. The core may then be magnetized, for example, by applying power to a relay coil that coils around a portion of the core. When the core is magnetized, the mirror flips. When power is removed from the relay coil and the core is demagnetized, the mirror flips back to the normal state.
The present self-testing aspects are not limited to the example smoke detector configurations in
For example, referring to
Referring to
In some aspects, one or more self-testing components (e.g., the controllable mirror 112, the light scattering surface 114, the self-test mirror 120, the shutter 115, the one or more external LEDs 116, the external controllable mirror 130, the external self-test mirror 132, etc.) may be configured similar to the various aspects described above to implement self-test functionality for self-testing the LED 104 and/or the photodetector 108 (e.g.,
For example, referring to
Alternatively, for example, referring to
Some alternative or additional aspects may implement masking self-test functionality in the smoke detector 90. For example, referring to
In some alternative aspects, for example, referring to
The processor 1602 may be a micro-controller and/or may include a single or multiple set of processors or multi-core processors. Moreover, the processor 1602 may be implemented as an integrated processing system and/or a distributed processing system. The computing device 1600 may further include a memory 1604, such as for storing local versions of applications being executed by the processor 1602, related instructions, parameters, etc. The memory 1604 may include a type of memory usable by a computer, such as random access memory (RAM), read only memory (ROM), tapes, flash drives, magnetic discs, optical discs, volatile memory, non-volatile memory, and any combination thereof. Additionally, the processor 1602 and the memory 1604 may include and execute an operating system executing on the processor 1602, one or more applications, display drivers, etc., and/or other components of the computing device 1600.
Further, the computing device 1600 may include a communications component 1606 that provides for establishing and maintaining communications with one or more other devices, parties, entities, etc., utilizing hardware, software, and services. The communications component 1606 may carry communications between components on the computing device 1600, as well as between the computing device 1600 and external devices, such as devices located across a communications network and/or devices serially or locally connected to the computing device 1600. For example, the communications component 1606 may include one or more buses, and may further include transmit chain components and receive chain components associated with a wireless or wired transmitter and receiver, respectively, operable for interfacing with external devices.
Additionally, the computing device 1600 may include a data store 1608, which can be any suitable combination of hardware and/or software, that provides for mass storage of information, databases, and programs. For example, the data store 1608 may be or may include a data repository for applications and/or related parameters not currently being executed by the processor 1602. In addition, the data store 1608 may be a data repository for an operating system, application, display driver, etc., executing on the processor 1602, and/or one or more other components of the computing device 1600.
The computing device 1600 may also include a user interface component 1610 operable to receive inputs from a user of the computing device 1600 and further operable to generate outputs for presentation to the user (e.g., via a display interface to a display device). The user interface component 1610 may include one or more input devices, including but not limited to a keyboard, a number pad, a mouse, a touch-sensitive display, a navigation key, a function key, a microphone, a voice recognition component, or any other mechanism capable of receiving an input from a user, or any combination thereof. Further, the user interface component 1610 may include one or more output devices, including but not limited to a display interface, a speaker, a haptic feedback mechanism, a printer, any other mechanism capable of presenting an output to a user, or any combination thereof.
At 1702, the method 1700 includes controlling one or more self-testing components of a smoke detector to re-direct at least a portion of light from an LED toward a photodetector, wherein the LED is configured to generate the light that is directed into a smoke chamber of the smoke detector, wherein the photodetector is configured to detect whether at least a threshold amount of the light is scattered by smoke particles when smoke is present in the smoke chamber. For example, referring to
At 1704, the method 1700 includes determining whether the photodetector causes an alarm trigger in response to the controlling. For example, the smoke detector 100 may determine whether the photodetector 108 triggers an alarm in response to configuring the controllable mirror 112 in the self-test state. The self-test of the smoke detector 100 has been successful if the photodetector 108 triggers an alarm in response to configuring the controllable mirror 112 in the self-test state.
In some optional aspects, controlling the one or more self-testing components at 1704 comprises at least one of: controlling a position or orientation of a controllable mirror to re-direct at least a portion of the light from the LED toward the photodetector or toward a light scattering surface configured to scatter the light toward the photodetector; or opening a shutter to allow at least a portion of the light from the LED to be re-directed by a mirror toward the photodetector or to be scattered by the light scattering surface toward the photodetector, as described herein with reference to various example aspects.
Some further example aspects are provided below.
1. A smoke detector, comprising:
a smoke chamber;
a light emitting diode (LED) configured to generate light that is directed into the smoke chamber;
a photodetector configured to detect whether at least a threshold amount of the light is scattered by smoke particles when smoke is present in the smoke chamber; and
one or more self-testing components configured to re-direct at least a portion of the light from the LED toward the photodetector for self-testing the LED and the photodetector.
2. The smoke detector of clause 1, wherein the one or more self-testing components include:
a light scattering surface facing the photodetector;
a controllable mirror having a position or orientation that is controllable between a normal state and a self-test state;
wherein, in the normal state, the controllable mirror is configured to avoid reflecting the light toward the light scattering surface; and
wherein, in the self-test state, the controllable mirror is positioned in a path of the light directed into the smoke chamber, and is configured in an orientation to reflect the light toward the light scattering surface to be scattered by the light scattering surface toward the photodetector.
3. The smoke detector of clause 1, wherein the one or more self-testing components include:
a light scattering surface facing the photodetector;
a self-test mirror positioned in a path of the light directed into the smoke chamber;
a shutter covering the self-test mirror and controllable between a closed state and an open state;
wherein, in the closed state, no light reaches the self-test mirror; and
wherein, in the open state, the light directed into the smoke chamber is reflected by the self-test mirror toward the light scattering surface to be scattered by the light scattering surface toward the photodetector.
4. The smoke detector of clause 1, wherein the one or more self-testing components include:
a light scattering surface facing the photodetector;
a self-test mirror positioned in a path of the light directed into the smoke chamber, wherein the light directed into the smoke chamber is reflected by the self-test mirror toward the light scattering surface;
a shutter covering the light scattering surface and controllable between a closed state and an open state;
wherein, in the closed state, no light reaches the light scattering surface; and
wherein, in the open state, the light directed into the smoke chamber is reflected by the self-test mirror toward the light scattering surface to be scattered by the light scattering surface toward the photodetector.
5. The smoke detector of clause 1, wherein the one or more self-testing components include:
a light scattering surface facing the photodetector;
a surface-mount controllable mirror having a position or orientation that is controllable between a normal state and a self-test state;
a self-test mirror positioned in a path of the light directed into the smoke chamber, wherein the light directed into the smoke chamber is reflected by the self-test mirror toward the surface-mount controllable mirror;
wherein, in the normal state, the surface-mount controllable mirror is configured to avoid reflecting the light toward the light scattering surface; and
wherein, in the self-test state, the surface-mount controllable mirror is configured in an orientation to reflect the light toward the light scattering surface to be scattered by the light scattering surface toward the photodetector.
6. The smoke detector of clause 1, wherein the one or more self-testing components include:
a light scattering surface facing the photodetector;
a surface-mount mirror;
a self-test mirror positioned in a path of the light directed into the smoke chamber, wherein the light directed into the smoke chamber is reflected by the self-test mirror toward the surface-mount mirror;
a shutter covering the self-test mirror and controllable between a closed state and an open state;
wherein, in the closed state, no light reaches the self-test mirror; and
wherein, in the open state, the light directed into the smoke chamber is reflected by the self-test mirror toward the surface-mount mirror and then by the surface-mount mirror toward the light scattering surface to be scattered by the light scattering surface toward the photodetector.
7. The smoke detector of clause 1, wherein the one or more self-testing components include:
a light scattering surface facing the photodetector;
a surface-mount mirror;
a self-test mirror positioned in a path of the light directed into the smoke chamber, wherein the light directed into the smoke chamber is reflected by the self-test mirror toward the surface-mount mirror;
a shutter covering the surface-mount mirror and controllable between a closed state and an open state;
wherein, in the closed state, no light reaches the surface-mount mirror; and
wherein, in the open state, the light directed into the smoke chamber is reflected by the self-test mirror toward the surface-mount mirror and then by the surface-mount mirror toward the light scattering surface to be scattered by the light scattering surface toward the photodetector.
8. The smoke detector of clause 1, wherein the one or more self-testing components include:
a light scattering surface facing the photodetector;
a surface-mount mirror;
a self-test mirror positioned in a path of the light directed into the smoke chamber, wherein the light directed into the smoke chamber is reflected by the self-test mirror toward the surface-mount mirror;
a shutter covering the light scattering surface and controllable between a closed state and an open state;
wherein, in the closed state, no light reaches the light scattering surface; and
wherein, in the open state, the light directed into the smoke chamber is reflected by the self-test mirror toward the surface-mount mirror and then by the surface-mount mirror toward the light scattering surface to be scattered by the light scattering surface toward the photodetector.
9. The smoke detector of clause 1, wherein the one or more self-testing components include:
a controllable mirror having a position or orientation that is controllable between a normal state and a self-test state;
wherein, in the normal state, the controllable mirror is configured to avoid reflecting the light toward the photodetector; and
wherein, in the self-test state, the controllable mirror is positioned in a path of the light directed into the smoke chamber, and is configured in an orientation to reflect the light toward the photodetector.
10. The smoke detector of clause 1, wherein the one or more self-testing components include:
a controllable light scattering surface having a position or orientation that is controllable between a normal state and a self-test state;
wherein, in the normal state, the controllable light scattering surface is configured to avoid scattering the light toward the photodetector; and
wherein, in the self-test state, the controllable light scattering surface is positioned in a path of the light directed into the smoke chamber, and is configured in an orientation to scatter the light toward the photodetector.
11. The smoke detector of clause 1, wherein the one or more self-testing components include:
a self-test mirror positioned in a path of the light directed into the smoke chamber;
a shutter covering the self-test mirror and controllable between a closed state and an open state;
wherein, in the closed state, no light reaches the self-test mirror; and
wherein, in the open state, the light directed into the smoke chamber is reflected by the self-test mirror toward the photodetector.
12. The smoke detector of clause 1, wherein the one or more self-testing components include:
a light scattering surface positioned in a path of the light directed into the smoke chamber;
a shutter covering the light scattering surface and controllable between a closed state and an open state;
wherein, in the closed state, no light reaches the light scattering surface; and
wherein, in the open state, the light directed into the smoke chamber is scattered by the light scattering surface toward the photodetector.
13. The smoke detector of clause 1,
wherein the one or more self-testing components comprise a controllable mirror positioned in a path of the light generated by the LED and having an orientation that is controllable between a normal state and a self-test state;
wherein, in the normal state, the controllable mirror reflects the light from the LED into the smoke chamber such that the light avoids the photodetector; and
wherein, in the self-test state, the controllable mirror is configured to reflect the light toward the photodetector.
14. The smoke detector of clause 1,
wherein the one or more self-testing components comprise a controllable light scattering surface positioned in a path of the light generated by the LED and having an orientation that is controllable between a normal state and a self-test state;
wherein, in the normal state, the controllable light scattering surface is configured to avoid scattering the light from the LED toward the photodetector; and
wherein, in the self-test state, the controllable light scattering surface is configured to scatter the light toward the photodetector.
15. The smoke detector of clause 1, further comprising:
a light scattering surface facing the photodetector;
one or more screens covering one or more smoke inlets of the smoke chamber;
one or more external LEDs configured external to the smoke chamber and configured to emit external light into the one or more screens and toward the light scattering surface; and
wherein, in absence of a masking of the smoke detector, at least a portion of the external light from the one or more external LEDs passes through the one or more screens and strikes the light scattering surface to be scattered toward the photodetector.
16. The smoke detector of clause 1, further comprising:
a light scattering surface facing the photodetector;
one or more screens covering one or more smoke inlets of the smoke chamber;
an external controllable mirror configured external to the smoke chamber and having a position or orientation that is controllable between a normal state and a self-test state;
wherein, in the normal state, the external controllable mirror is configured to avoid reflecting the light through the one or more screens and toward the light scattering surface; and
wherein, in the self-test state, the external controllable mirror is positioned in a path of the light directed into the smoke chamber;
wherein, in the self-test state, and in absence of a masking of the smoke detector, the external controllable mirror is configured in an orientation to reflect the light through the one or more screens and toward the light scattering surface to be scattered by the light scattering surface toward the photodetector.
17. The smoke detector of clause 1, further comprising:
a light scattering surface facing the photodetector;
one or more screens covering one or more smoke inlets of the smoke chamber;
an external self-test mirror configured external to the smoke chamber and positioned in a path of the light directed into the smoke chamber;
a shutter covering the external self-test mirror and controllable between a closed state and an open state;
wherein, in the closed state, no light reaches the external self-test mirror; and
wherein, in the open state, and in absence of a masking of the smoke detector, the light directed into the smoke chamber passes through the one or more screens and is reflected by the external self-test mirror back through the one or more screens and toward the light scattering surface to be scattered by the light scattering surface toward the photodetector.
18. A smoke detector, comprising:
a smoke chamber;
a photodetector configured to detect at least a portion of scattered light when scattered by smoke particles when smoke is present in the smoke chamber; and
one or more masking self-test components configured external to the smoke chamber and configured to direct light from outside the smoke chamber into the smoke chamber and toward the photodetector for determining whether the smoke detector has been masked.
19. The smoke detector of clause 18, further comprising:
a light scattering surface facing the photodetector;
one or more screens covering one or more smoke inlets of the smoke chamber;
wherein the one or more masking self-test components comprise one or more external light emitting diodes (LEDs) configured external to the smoke chamber and configured to emit external light into the one or more screens and toward the light scattering surface; and
wherein, in absence of a masking of the smoke detector, at least a portion of the external light from the one or more external LEDs passes through the one or more screens and strikes the light scattering surface to be scattered toward the photodetector.
20. The smoke detector of clause 18, further comprising:
a light emitting diode (LED) configured to generate light that is directed into the smoke chamber;
a light scattering surface facing the photodetector;
one or more screens covering one or more smoke inlets of the smoke chamber;
wherein the one or more masking self-test components comprise an external controllable mirror configured external to the smoke chamber and having a position or orientation that is controllable between a normal state and a self-test state;
wherein, in the normal state, the external controllable mirror is configured to avoid reflecting the light through the one or more screens and toward the light scattering surface; and
wherein, in the self-test state, the external controllable mirror is positioned in a path of the light directed into the smoke chamber;
wherein, in the self-test state, and in absence of a masking of the smoke detector, the external controllable mirror is configured in an orientation to reflect the light through the one or more screens and toward the light scattering surface to be scattered by the light scattering surface toward the photodetector.
21. The smoke detector of clause 18, further comprising:
a light emitting diode (LED) configured to generate light that is directed into the smoke chamber;
a light scattering surface facing the photodetector;
one or more screens covering one or more smoke inlets of the smoke chamber;
wherein the one or more masking self-test components comprise:
an external self-test mirror configured external to the smoke chamber and positioned in a path of the light directed into the smoke chamber; and
a shutter covering the external self-test mirror and controllable between a closed state and an open state;
wherein, in the closed state, no light reaches the external self-test mirror; and
wherein, in the open state, and in absence of a masking of the smoke detector, the light directed into the smoke chamber passes through the one or more screens and is reflected by the external self-test mirror back through the one or more screens and toward the light scattering surface to be scattered by the light scattering surface toward the photodetector.
22. A method, comprising:
controlling one or more self-testing components of a smoke detector to re-direct at least a portion of light from a light emitting diode (LED) toward a photodetector, wherein the LED is configured to generate the light that is directed into a smoke chamber of the smoke detector, wherein the photodetector is configured to detect whether at least a threshold amount of the light is scattered by smoke particles when smoke is present in the smoke chamber; and
determining whether the photodetector causes an alarm trigger in response to the controlling.
23. The method of clause 22, wherein controlling the one or more self-testing components comprises at least one of:
controlling a position or orientation of a controllable mirror to re-direct at least a portion of the light from the LED toward the photodetector or toward a light scattering surface configured to scatter the light toward the photodetector; or
opening a shutter to allow at least a portion of the light from the LED to be re-directed by a mirror toward the photodetector or to be scattered by the light scattering surface toward the photodetector.
The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any aspect described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other aspects. Unless specifically stated otherwise, the term “some” refers to one or more. Combinations such as “at least one of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or any combination thereof” include any combination of A, B, and/or C, and may include multiples of A, multiples of B, or multiples of C. Specifically, combinations such as “at least one of A, B, or C,” “one or more of A, B, or C,” “at least one of A, B, and C,” “one or more of A, B, and C,” and “A, B, C, or any combination thereof” may be A only, B only, C only, A and B, A and C, B and C, or A and B and C, where any such combinations may contain one or more member or members of A, B, or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. The words “module,” “mechanism,” “element,” “device,” and the like may not be a substitute for the word “means.” As such, no claim element is to be construed as a means plus function unless the element is expressly recited using the phrase “means for.”
