Patent Description:
Safety of people is of utmost importance and to save people from any untoward situation is a major concern. Over a period of time, several preventive measures have been taken to save people from any untoward incidents like smoke/fire breakouts. Such preventive measures may involve deploying several fire/smoke detectors (such as aspirating smoke detector/s (ASD)) in a premises (e.g. building, floors, rooms, museums, hospitals, colleges etc.). Such aspirating smoke detector/s raises alarm or notify people present in the premises on sensing presence of smoke/fire particles in air.

For example, <CIT> discloses a system comprising a smoke detection unit comprising a fan.

The aspirating smoke detector deploy one or more fans to draw air from their surroundings. When the fan/s draws air from the surroundings, it produces noise. Such noise disturbs people present in the premises and may cause discomfort to them. <CIT> discloses a technique for reducing the acoustic noise of a cooling fan in a projector having a high-power lamp. At present, there is no solution available in the market that eliminates disturbance by the noise originating from the one or more fans of the aspirating smoke detector/s.

In view of the afore-mentioned problems in the existing solutions, there is a need of an efficient and effective system and method for eliminating disturbance caused by noise originating by one or more fans of aspirating smoke detector/s. There is also a need to eliminate discomfort caused to the people by such noise. In order to solve problems in the existing solutions, a system and a method are disclosed.

The present invention provides a system according to claim <NUM> and a method according to claim <NUM>.

Various embodiments of the invention describe a system for suppressing noise produced by a fire/smoke detection unit. The system comprises a fire/smoke detection unit and a noise cancellation unit communicably coupled with the fire/smoke detection unit. The fire/smoke detection unit comprises a fan adapted to draw air through a conduit, the fan producing noise while drawing the air. The noise cancellation unit comprises a microphone adapted to receive the noise of the fan and derive a noise signal from the noise. There is a speed detection unit to detect the speed of the fan. The noise cancellation unit also comprises an amplifier adapted to amplify the noise signal received from the microphone and a phase-shift unit adapted to shift a phase of the amplified noise signal received from the amplifier to produce an anti-phase noise signal. The anti-phase noise signal is dependent on the detected speed of the fan. The noise cancellation unit further comprises a speaker adapted to output the anti-phase noise signal received from the phase-shift unit. An amplitude of the anti-phase noise signal is based on the speed of the fan.

In an embodiment of the invention, the anti-phase noise signal suppresses the noise produced by the fan of the fire/smoke detection unit.

In yet another embodiment of the invention, the noise signal and the anti-phase noise signal are at <NUM> degree of phase shift with respect to each other.

In still another embodiment of the invention, the amplifier amplifies the noise signal based on a threshold value required to suppress the noise produced by the fan.

In a different embodiment of the invention, the microphone and the fan are located in proximity with each other. Also, the speaker and the fan are located in proximity with each other.

In yet another embodiment of the invention, the noise cancellation unit comprises a power amplifier to amplify the anti-phase noise signal produced by the phase-shift unit.

In another embodiment of the invention, the fan and the conduit are coupled with the fire/smoke detection unit. Also, the fire/smoke detection unit is placed inside a premises.

Various embodiments of the invention describe a method for suppressing noise produced by a fire/smoke detection unit. The method comprises steps of receiving noise by a microphone and deriving a noise signal from the noise. The noise is produced by a fan of a fire/smoke detection unit while drawing air. The speed of the fan is detected. The method also comprises the step of amplifying the noise signal by the amplifier received from the microphone and producing an anti-phase noise signal by shifting a phase of the amplified noise signal received from the amplifier wherein the anti-phase noise signal is dependent on the detected speed of the fan. The method comprises further steps of outputting the anti-phase noise signal through a speaker. An amplitude of the anti-phase noise signal is based on the speed of the fan.

In yet another embodiment of the invention, the anti-phase noise signal produced by the phase-shift unit is amplified by a power amplifier.

In another embodiment of the invention, the fan draws air through a conduit coupled with the fire/smoke detection unit.

Other aspects, advantages, and salient features of the invention will become apparent to those skilled in the art from the following detailed description, which taken in conjunction with the annexed drawings, discloses exemplary embodiments of the invention.

Described herein is the technology with a system and a method for suppressing noise produced by a fire/smoke detection unit/s. The fire/smoke detection unit/s is installed in a premises to detect fire/smoke in the premises. To detect fire/smoke in the premises, the fire/smoke detection unit/s comprise one or more fans to draw air from surroundings or present in the premises. The one or more fans draw air from the surroundings through conduit/s. When the one or more fans draw air from the surroundings through the conduit/s, the one or more fans produce noise in the premises.

In order to suppress the noise produced by the one or more fans of the fire/smoke detection unit/s, a noise cancellation unit communicably coupled with the fire/smoke detection unit/s is used. The noise produced by the one or more fans is provided as an input to the noise cancellation unit. The input to the noise cancellation unit is provided through a microphone of the noise cancellation unit. The microphone derives a noise signal from the noise as inputted to the microphone. Also, speed of the fan is detected by the noise cancellation unit. Then, the noise signal is amplified by an amplifier and the amplified noise signal is provided to a phase-shift unit. The phase-shift unit produces an anti-phase noise signal based on the amplified noise signal and the anti-phase noise signal is dependent on the detected speed of the fan. The anti-phase noise signal is outputted by a speaker to suppress the noise produced by the fire/smoke detection unit/s.

As used herein, the premises may be rooms, floors or a building where the fire/smoke detection unit/s may be installed. Also, the fire/smoke detection unit/s may cover a distance range of <NUM> meters to <NUM> meters. Further, several fire/smoke detection unit/s may be installed in each of the room or floor. For an instance, each room may have <NUM> fire/smoke detection unit/s installed or each floor may have <NUM> fire/smoke detection unit/s installed or a building may have <NUM> fire/smoke detection unit/s.

As used herein, the fire/smoke detection unit/s may detect presence of fire/smoke in the air. The fire/smoke detection unit/s may comprise, but is not limited to, one or more fans to draw air from surroundings through conduits, nephelometer, fire/smoke chamber, dust filter/s, battery, and/or sensors. The fire/smoke detection unit/s may be an aspirating smoke detector (ASD) or any such detector having one or more fans producing the noise and is well known in the art.

As used herein, the microphone may be a transducer for converting sound of the noise produced by the one or more fans to a noise signal (i.e. an electrical signal). The microphones may be a capacitor microphone or an electrostatic microphone, a RF condenser microphones, an electret microphone, a dynamic microphone, crystal microphone or piezo microphones, fiber-optic microphones, laser microphones, MicroElectrical-Mechanical System (MEMS) microphones, or any such microphone/s that is well known in the art.

As used herein, the amplifier may be an electronic component for amplifying the noise signal. The amplifier may either increase amplitude of the noise signal. The amplifier may be a power amplifier, an operational amplifier (op-amp), a distributed amplifier, a switched mode amplifier, negative resistance amplifier or any such amplifier that is well known in the art.

As used herein, the phase-shift unit may be a device for changing a phase (in degrees) of the amplified noise signal to produce an anti-phase noise signal, as described herein in the specification. Such phase-shift unit may shift the phase that is well known in the art.

As used herein, the speaker may be a wired speaker or wireless speaker that converts the anti-phase noise signal into sound and outputs the sound. Such speaker may be a loudspeaker or any such speaker that is well known in the art.

<FIG> depicts a system architecture <NUM> for suppressing noise produced by one or more fire/smoke detection units, according to an exemplary embodiment of the invention. As depicted in <FIG>, the one or more fire/smoke detection units <NUM> are installed in a premises <NUM>. The fire/smoke detection units <NUM> comprises one or more fans <NUM> for drawing air from the premises <NUM> or from surroundings. The air is drawn by the one or more fans <NUM> through an inlet conduit 106A coupled/attached with the one or more fans <NUM>. The conduit/s 106A may provide the air to a dust filter and then to a fire/smoke chamber <NUM> that detects presence of fire/smoke particles in the air. In an exemplary embodiment, the detection of presence of fire/smoke particles in the air may be performed by light scattered by the fire/smoke particles in the air. When the fire/smoke chamber <NUM> of the fire/smoke detection units <NUM> detects that the fire/smoke particles present in the air are above a specified threshold, then, the fire/smoke detection units <NUM> may raise an alarm to notify people present in the premises <NUM>. Also, the air may exit the fire/smoke detection units <NUM> through an exhaust conduit 106B coupled/attached with the one or more fans <NUM> as shown in the <FIG>. The other methods of detecting the smoke/fire are also within the scope of the present invention.

Also, when the one or more fans <NUM> of the fire/smoke detection units <NUM> draws air from the premises <NUM> or from surroundings, the one or more fans <NUM> produce noise. To suppress the noise produced by one or more fans <NUM>, a noise cancellation unit <NUM> is used that is communicably coupled with the fire/smoke detection units <NUM>. The details of how different components of the noise cancellation unit <NUM> suppresses the noise has been explained in <FIG>.

Although <FIG> depicts that the fire/smoke detection units <NUM> outside the premises <NUM>; however; it is understood by a person killed in the art that the fire/smoke detection units <NUM> is installed inside or outside or at any place relative to the premises <NUM>. Although <FIG> depicts only one fan <NUM> in the premises <NUM>; however; it is understood by a person killed in the art that the premises <NUM> may have any number of fans installed at several places of the premises <NUM>.

<FIG> depicts a block diagram of different components of a noise cancellation unit <NUM> communicably coupled with fire/smoke detection units <NUM> for suppressing noise produced by one or more fans <NUM> of the fire/smoke detection units <NUM> according to an exemplary embodiment of the invention. The noise cancellation unit <NUM> may comprise of, but is not limited to, a microphone <NUM>, an amplifier <NUM>, a speaker <NUM>, a phase-shift unit <NUM> a power amplifier <NUM> and/or a speed detection unit <NUM>. When the one or more fans <NUM> of the fire/smoke detection unit <NUM> produces noise, the microphone <NUM> is adapted to receive the noise from the one or more fans <NUM> as an input. The microphone <NUM> and the one or more fans <NUM> are located in proximity with each other so that the microphone <NUM> receive the noise from the one or more fans <NUM> as an input. On receiving the noise from the one or more fans <NUM>, the microphone <NUM> is adapted to derive a noise signal and provide the noise signal to the amplifier <NUM> and/or the speed detection unit <NUM> of the noise cancellation unit <NUM>. Also, the speed detection unit <NUM> is adapted to detect a speed of the one or more fans <NUM> of the fire/smoke detection unit <NUM>. In an exemplary embodiment, the speed of the one or more fans <NUM> may be detected based on an amplitude or a frequency of the noise signal as derived by the microphone <NUM>. For an instance, the speed of a fan may be determined as <NUM> rotations per minute.

The amplifier <NUM> is adapted to amplify the noise signal received from the microphone <NUM>. In an exemplary embodiment, the amplifier <NUM> may amplify an amplitude of the noise signal. After amplifying the noise signal, the amplifier <NUM> is adapted to output an amplified noise signal and is also adapted to provide the amplified noise signal to a phase-shift unit <NUM>. The phase-shift unit <NUM> is adapted to shift a phase of the amplified noise signal to produce an anti-phase noise signal. In an exemplary embodiment, the phase-shift unit <NUM> may shift or change a phase of the amplified noise signal by <NUM> degrees. Further, the phase-shift unit <NUM> may shift or change a phase of the amplified noise signal in such a way that the anti-phase noise signal is an inverted image of the noise signal. The amplification of the noise signal and phase shifting of the amplified noise signal has been explained in <FIG> with an example.

Moreover, the anti-phase noise signal is dependent on the detected speed of the one or more fans <NUM> of the fire/smoke detection unit <NUM>. The phase-shift unit <NUM> produces a phase shifted anti-phase noise signal based on the detected speed of the one or more fans <NUM>. Also, the detected speed of the one or more fans <NUM> may be mapped with the amplitude and/or frequency of the anti-phase noise signal as the amplitude and/or the frequency of the fans <NUM> are effected by speed of the fans <NUM>.

Considering an example, if the speed of a fan is <NUM> rotations per minute, then the anti-phase noise signal may be produced in such a way that the anti-phase noise signal (when outputted) should be able to suppress the noise made by the fan in each rotation per minute. In this case, the amplitude of the anti-phase noise signal may be calculated as <NUM> decibels (dB) to suppress the noise.

In one exemplary embodiment, the phase-shift unit <NUM> may also be adapted to provide the anti-phase noise signal to the speaker <NUM>. The speaker <NUM> is adapted to output the anti-phase noise signal received from the phase-shift unit <NUM>. The speaker <NUM> may output the anti-phase noise signal as sound. For this, the speaker <NUM> and the one or more fans <NUM> are also located in proximity with each other in order to suppress the noise produced by the one or more fans <NUM> of the fire/smoke detection unit <NUM>.

In alternative exemplary embodiment, the phase-shift unit <NUM> may also be adapted to provide the anti-phase noise signal to the power amplifier <NUM>. The power amplifier <NUM> may be adapted to amplify the anti-phase noise signal received from the phase-shift unit <NUM>. In an exemplary embodiment, the power amplifier <NUM> may amplify a frequency of the anti-phase noise signal. In another exemplary embodiment, the power amplifier <NUM> may amplify an amplitude of the anti-phase noise signal. The amplification of the anti-phase noise signal may also be dependent on speed of the one or more fans <NUM>. The anti-phase noise signal may be amplified by the power amplifier <NUM> in such a way that the anti-phase noise signal (when outputted) should be able to suppress the noise made by a fan <NUM> in each rotation per minute. After amplifying the anti-phase noise signal, the power amplifier <NUM> may be adapted to output an amplified anti-phase noise signal and may also be adapted to provide the amplified anti-phase noise signal to the speaker <NUM>. The speaker <NUM> is adapted to output the anti-phase noise signal received from the phase-shift unit. This would cancel/suppress the noise produced by the one or more fans <NUM> of the fire/smoke detection unit <NUM>. For an instance, <NUM> decibel of noise is measured at <NUM> meter distance in a single detector <NUM> at blower speed <NUM> and <NUM> decibels of noise is measured in a single detector <NUM> at blower speed <NUM>. The present invention cancels/suppresses such noise to a great extent.

The different units described herein are exemplary. The invention may be performed using one or more units. For example, the tasks executed by the microphone <NUM>, the amplifier <NUM>, the speaker <NUM>, the phase-shift unit <NUM>, the power amplifier <NUM> and/or the speed detection unit <NUM> may be performed by a single unit. Alternatively more number of units as described herein may be used to perform the invention.

<FIG> depicts an exemplary noise signal, <FIG> depicts an exemplary amplified noise signals amplified by amplitude and <FIG> depict exemplary anti-phase noise signal according to an exemplary embodiment of the invention. As can be seen, the exemplary noise signal 300A in <FIG> has a single frequency (i.e. "f") in one cycle of <NUM> degree. At <NUM> degree, the exemplary noise signal 300A has f/<NUM> as frequency. Referring to <FIG>, when the exemplary noise signal 300A is amplified by the amplifier <NUM>, the amplified noise signal 300B is produced when the amplifier <NUM> amplifies the exemplary noise signal 300A by amplitude. As can be seen, the exemplary amplified noise signal 300B has <NUM> decibels (dB) measured as amplitude whereas the exemplary noise signal 300A has <NUM> decibels (dB) measured as amplitude. Referring to <FIG>, when the exemplary amplified noise signal 300B (by amplitude) is phase-shifted by <NUM> degrees by a phase-shift unit <NUM>, the exemplary anti-phase noise signal 300C is produced by the phase-shift unit <NUM>. As can be seen, the exemplary anti-phase noise signal 300C is an inverted image of the exemplary amplified noise signal 300B.

The amplifier <NUM> may amplify the exemplary noise signal 300A based on a threshold value of amplitude that would be required to suppress the noise produced by the one or more fans <NUM>. Such threshold value may be automatically determined by the amplifier <NUM> on analyzing the exemplary noise signal 300A and by taking the speed of the one or more fans <NUM> into consideration. Accordingly, the amplifier <NUM> may amplify the exemplary noise signal 300A to increase power of the exemplary noise signal 300A.

<FIG> depicts a flowchart outlining the features of the invention in an exemplary embodiment of the invention. The method flowchart <NUM> describes a method for suppressing noise produced by a fire/smoke detection unit/s <NUM>. The method flowchart <NUM> starts at step <NUM>.

At step <NUM>, microphone/s <NUM> of a noise cancellation unit <NUM> receives noise as an input from one or more fans <NUM> of a fire/smoke detection unit <NUM>. The microphone <NUM> of the noise cancellation unit <NUM> derives a noise signal from the noise produced by the one or more fans <NUM> while drawing air from surroundings.

At step <NUM>, a speed detection unit <NUM> of the noise cancellation unit <NUM> detects a speed of the one or more fans <NUM> as discussed above.

At step <NUM>, an amplifier <NUM> of the noise cancellation unit <NUM> amplifies the noise signal received from the microphone <NUM>. In an exemplary embodiment, the amplifier <NUM> amplifys a frequency of the noise signal as illustrated in <FIG>. In another exemplary embodiment, the amplifier <NUM> amplifies an amplitude of the noise signal as illustrated in <FIG>. After amplifying the noise signal, the amplifier <NUM> outputs an amplified noise signal and provides the amplified noise signal to a phase-shift unit <NUM>.

At step <NUM>, the phase-shift unit <NUM> of the noise cancellation unit <NUM> shifts a phase of the amplified noise signal to produce an anti-phase noise signal. In an exemplary embodiment, the phase-shift unit <NUM> may shift or change a phase of the amplified noise signal by <NUM> degrees. Further, the phase-shift unit <NUM> may shift or change a phase of the amplified noise signal in such a way that the anti-phase noise signal is an inverted image of the amplified noise signal. Also, the phase-shift unit <NUM> provides the anti-phase noise signal to a speaker <NUM>. The anti-phase noise signal is also dependent on the detected speed of the one or more fans <NUM> as explained above.

At step <NUM>, the speaker <NUM> of the noise cancellation unit <NUM> outputs the anti-phase noise signal received from the phase-shift unit <NUM>. The speaker <NUM> may output the anti-phase noise signal as sound. This would suppress the noise produced by the one or more fans <NUM> of the fire/smoke detection unit <NUM>. Then, the method flowchart <NUM> ends at <NUM>.

The present invention is applicable to various fields such as, but not limited to, hospitality industry, museums, libraries, colleges, universities, hospitals, offices and any such building that is well known in the art and where the fire/smoke detection unit produces noise which needs to be suppressed.

The present invention provides the following technical advantages over the existing solutions a) suppresses noise produced by fan/s of fire/smoke detection unit, b) usage of a noise cancellation unit along with the fire/smoke detection unit to suppress noise produced by fan/s, and c) eliminates discomfort and disturbance caused to people because of noise produced by fan/s, d) automated way to reduce noise produced by fan/s.

The order of execution or performance of the operations in examples of the invention illustrated and described herein is not essential, unless otherwise specified. That is, the operations may be performed in any order, unless otherwise specified, and examples of the invention may include additional or fewer operations than those disclosed herein. For example, it is contemplated that executing or performing a particular operation before, contemporaneously with, or after another operation is within the scope of aspects of the invention.

When introducing elements of aspects of the invention or the examples thereof, the articles "a," "an," "the," and "said" are intended to mean that there are one or more of the elements. " The phrase "one or more of the following: A, B, and C" means "at least one of A and/or at least one of B and/or at least one of C".

Having described aspects of the invention in detail, it will be apparent that modifications and variations are possible without departing from the scope of aspects of the invention as defined in the appended claims. As various changes could be made in the above constructions, products, and methods without departing from the scope of aspects of the invention, it is intended that all matter contained in the above description and shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Claim 1:
A system (<NUM>) comprising:
- a fire/smoke detection unit (<NUM>) comprising:
a fan (<NUM>) adapted to draw air through a conduit, the fan (<NUM>) producing noise while drawing the air;
the system (<NUM>) being characterized in that it further comprises:
- a noise cancellation unit (<NUM>) communicably coupled with the fire/smoke detection unit (<NUM>), the noise cancellation unit (<NUM>) comprising:
a microphone (<NUM>) adapted to receive the noise of the fan (<NUM>) and deriving a noise signal from the noise;
a speed detection unit (<NUM>) to detect the speed of the fan (<NUM>);
an amplifier (<NUM>) adapted to amplify the noise signal received from the microphone (<NUM>);
a phase-shift unit (<NUM>) adapted to shift a phase of the amplified noise signal received from the amplifier to produce an anti-phase noise signal, wherein the anti-phase noise signal is dependent on the detected speed of the fan (<NUM>); and
a speaker (<NUM>) adapted to output the anti-phase noise signal received from the phase-shift unit,
wherein an amplitude of the anti-phase noise signal is based on the speed of the fan (<NUM>).