Patent Description:
Smoke detectors, also known as smoke-sensitive fire detectors or smoke-sensing detectors, are commonly used in buildings to detect smoke generated in a fire and then send a warning signal. The smoke detector typically includes a sensing chamber in which a light emitter, a light receiver and a sensing area are included. When the smoke reaches a certain concentration in the sensing area, light emitted by the light emitter is scattered to the light receiver at an intensity that reaches a critical value, thereby generating a signal and sending an alarm.

The cost of a smoke detector depends on the size of the sensing chamber thereof. As the size of the sensing chamber decreases, a distance between a side wall of the sensing chamber and the light emitter will decrease, resulting in stronger background light which may include a scattered portion of the light emitted by the light emitter and a light refracted or reflected by the wall of the sensing chamber. Such background light as a base noise may affect the normal operation of the smoke detector.

<CIT> discloses a scattered-light type smoke sensor according to the preamble of claim <NUM>, wherein any detrimental effect of vibration from an alarm sound generator on the sensitivity of the smoke detector is minimized by the configuration of vent holes on the device. A light shielding wall is provided in the vicinity of a smoke sensing region to prevent light emitted from a light emitting unit from directly entering a light receiving unit.

<CIT> discloses an optical smoke detection unit, e.g., for a smoke detector, that may include first and second light-emitting diodes for emitting monochromatic, dichromatic or polychromatic light, an optical receiver for smoke detection, and a control unit that controls the light-emitting diodes and evaluates a receive signal output by the optical receiver for fire parameters. The light-emitting diodes may be optically coupled together such that at least one of the light-emitting diodes illuminates the other.

<CIT> discloses a smoke detector labyrinth structure characterized by comprising two transmitting devices and a receiving device.

An object of the present disclosure is to solve or at least alleviate the problems in the prior art.

According to some aspects, a smoke detector is provided, which includes:.

Optionally, in the smoke detector, some of the sub-baffles extend toward the radial direction of the first light emitter.

Optionally, in the smoke detector, the branch portion is divergent in cross-section.

Optionally, in the smoke detector, the sensing chamber is cylindrical.

Optionally, in the smoke detector, some of the sub-baffles extend toward the radial direction of the first light emitter, and some of the sub-baffles extend toward the radial direction of the second light emitter.

Optionally, in the smoke detector, the sensing chamber includes an opening, a sidewall and a bottom wall, and the sidewall of the sensing chamber is toothed.

Optionally, in the smoke detector, the sensing chamber is configured to be formed by assembling a smoke guiding cover, a labyrinth body and a labyrinth base.

Optionally, in the smoke detector, the first baffle is fixed to the labyrinth base.

Optionally, in the smoke detector, the labyrinth base defines a light emitter holder and a light receiver holder, and the first light emitter and the first light receiver are respectively located in the light emitter holder and the light receiver holder, wherein pins of the first light emitter and the first light receiver are connected to the circuit board after passing through the labyrinth base, and the labyrinth body defines a light emitter cover and a light receiver cover; when the labyrinth body and the labyrinth base are assembled together, the first light emitter is fixed between the light emitter holder and the light emitter cover, and the first light receiver is fixed between the light receiver holder and the light receiver cover.

The smoke detector according to the present disclosure has a simple structure, effectively weakens a background light in the sensing chamber, and ensures a normal operation of the smoke detector especially in a case where a volume of the sensing chamber is small.

The contents of the present disclosure will become more easily understood with reference to the accompanying drawings. Those skilled in the art can readily appreciate that the drawings are for illustrative purposes only, instead of being intended to limit the scope of protection of the present disclosure. In addition, similar numbers in the drawings are used to indicate similar parts, wherein:.

It will be readily understood that, based on the technical solutions of the present disclosure, those skilled in the art can propose various alternative embodiments and implementations without departing from the scope of the present invention as defined by the claims. Therefore, the following detailed description and the accompanying drawings are merely exemplary description of the technical solutions of the present disclosure, which shall not be deemed as the whole of the present disclosure or as limiting or restricting the technical solutions of the present disclosure.

Such orientation terms as upper, lower, left, right, front, rear, front side, back side, top, bottom or the like that are mentioned or may be mentioned in this description are defined with respect to the configurations shown in the individual drawings. They are relative concepts and thus possibly vary according to their different locations and different usage states. Therefore, these or other orientation terms shall not be interpreted as limiting terms.

Referring first to <FIG>, an exploded view of a smoke detector according to an embodiment of the present disclosure is shown.

In some embodiments, the smoke detector may include:.

This type of smoke detector operates following this principle: when smoke has not yet entered the sensing chamber, the light receiver receives only a small amount of background light (also referred to as base noise), which may be a scattered light of the light emitted by the light emitter, or a reflected light from an inner wall of the sensing chamber. When the smoke enters the sensing area of the sensing chamber, the light emitted by the light emitter will be refracted by the smoke to the light receiver, causing the intensity of light received by the light receiver to increase to a critical value. For example, the light receiver may be a photosensitive diode, which sends a signal when the intensity of light increases to the critical value, so that an alarm system or the like may be activated.

As described in the background art, as the volume of the sensing chamber becomes smaller, the background light or base noise in the sensing chamber will increase, thus affecting a normal operation of the smoke detector. The smoke detector according to the embodiment of the present disclosure provides the following structure to attenuate background light. Specifically, referring to <FIG> and <FIG>, the smoke detector according to the embodiment of the present disclosure further includes a first baffle <NUM> in the sensing chamber. The first baffle <NUM> is disposed adjacent to the first light emitter <NUM> located in a light emitter holder <NUM>, and the first baffle <NUM> includes a baffle body <NUM> extending from the periphery of the sensing chamber toward the middle portion, and a branch portion <NUM> extending from the baffle body <NUM>, the branch portion <NUM> including a plurality of sub-baffles <NUM>, <NUM>, <NUM> and <NUM> branching off the baffle body <NUM>. In the illustrated embodiment, the branch portion <NUM> may be divergent in cross-section, similar to the shape of a hand, including four sub-baffles <NUM>, <NUM>, <NUM> and <NUM>. In alternative embodiments, the branches <NUM> may have other shapes and may have different numbers of sub-baffles, such as two, three, or five, and the like. The unique structure of the first baffle <NUM> effectively weakens a scattered portion of the light emitted from the light emitter <NUM> and a reflected light from the side wall, thereby effectively reducing the background light in the sensing chamber.

In some embodiments, some of the sub-baffles are tilted or referred as deflected, or referred to as extending toward the radial direction of the first light emitter <NUM>. In the embodiment shown in <FIG>, the sub-baffles <NUM>, <NUM> extend toward the radial direction of the first light emitter <NUM>, and the sub-baffle <NUM> extend toward the radial direction of the second light emitter <NUM>, so that scattered portions of lights emitted by the first light emitter <NUM> and the second light emitter <NUM> are effectively blocked. On the other hand, the sub-baffles <NUM>, <NUM>, <NUM>, <NUM> will not block the main light path, and thus will not affect a normal operation of the smoke detector.

Referring to <FIG>, in some embodiments, the sensing chamber may include an opening, a side wall, and a bottom wall. In the illustrated embodiment, the opening of the sensing chamber is constituted by an smoke inlet <NUM> of a smoke guiding cover <NUM>, the side wall of the sensing chamber is constituted by a side wall <NUM> of the labyrinth body <NUM>, and the bottom wall of the sensing chamber is constituted by a bottom wall <NUM> of the labyrinth base <NUM>. In some embodiments, the sensing chamber is substantially cylindrical, and in alternative embodiments, the sensing chamber may have other suitable shapes. In some embodiments, the side wall of the sensing chamber, i.e., the side wall <NUM> of the labyrinth body <NUM>, is toothed to effectively suppress reflection of light by the side wall, thereby further weakening the background light. In some embodiments, as shown, the first baffle <NUM> and optional a second baffle <NUM> and a third baffle <NUM> are each fixed to the labyrinth base <NUM>. Alternatively, the baffles may also extend out from the side wall of the labyrinth body or the smoke guiding cover. In some embodiments, the labyrinth base <NUM> defines light emitter holders <NUM>, <NUM> and a light receiver holder <NUM>, wherein the first light emitter <NUM>, the second light emitter <NUM>, and the first light receiver <NUM> are located in the light emitter holders <NUM>, <NUM> and the light receiver holder <NUM> respectively. Pins of the first light emitter <NUM>, the second light emitter <NUM> and the first light receiver <NUM> are connected to the circuit board <NUM> after passing through the labyrinth base <NUM>. The labyrinth body <NUM> defines light emitter covers <NUM>, <NUM> and a light receiver cover <NUM>. After the labyrinth body <NUM> and the labyrinth base <NUM> are assembled together, the first light emitter <NUM> is fixed between the light emitter holder <NUM> and the light emitter cover <NUM>, the second light emitter <NUM> is fixed between the light emitter holder <NUM> and the light emitter cover <NUM>, and the first light receiver <NUM> is fixed between the light receiver holder <NUM> and the light receiver cover <NUM>.

Referring specifically to <FIG>, in this embodiment, the first light emitter <NUM> and the first light receiver <NUM> are arranged at a central angle b between <NUM>° and <NUM>°, a second light emitter <NUM> is disposed in the sensing chamber, and the second light emitter <NUM> is located between the first light emitter <NUM> and the first light receiver <NUM> and spaced apart from the first light receiver <NUM> by a central angle a of less than <NUM>°; wherein the first baffle <NUM> is located between the first light emitter <NUM> and the second light emitter <NUM>, part of the sub-baffles <NUM>, <NUM> extend toward the radial direction of the first light emitter <NUM>, and part of the sub-baffles <NUM> extend toward the radial direction of the second light emitter <NUM>. A second baffle <NUM> extending from the periphery of the sensing chamber toward the middle portion is further disposed between the second light emitter <NUM> and the first light receiver <NUM>. The second baffle <NUM> blocks part of the background light. A third baffle <NUM> is further disposed at the outer side of the first light receiver <NUM>, and an inner end (the end near the center) of the third baffle <NUM> extends toward the radial direction of the first light receiver <NUM>. The third baffle <NUM> further weakens the background light that may be incident on the first light receiver <NUM>.

Claim 1:
A smoke detector, comprising:
a housing (<NUM>, <NUM>);
a sensing chamber (<NUM>, <NUM>, <NUM>) in the housing, wherein in the sensing chamber, a first light emitter (<NUM>) and a first light receiver (<NUM>) are disposed at the periphery of the sensing chamber and facing a middle portion of the sensing chamber, the first light emitter (<NUM>) and the first light receiver (<NUM>) being arranged at a central angle between <NUM>° and <NUM>°;
a first baffle (<NUM>) in the sensing chamber, the first baffle being disposed adjacent to the first light emitter and including a baffle body (<NUM>) and a branch portion (<NUM>), the baffle body extending from the periphery of the sensing chamber toward the middle portion, and the branch portion including a plurality of sub-baffles (<NUM>, <NUM>, <NUM>, <NUM>) branching off the baffle body; and
a circuit board (<NUM>) electrically connected to the first light emitter (<NUM>) and the first light receiver (<NUM>) respectively;
characterized in that the smoke detector further comprises:
a second light emitter (<NUM>) disposed in the sensing chamber (<NUM>, <NUM>, <NUM>), the second light emitter being located between the first light emitter and the first light receiver and spaced apart from the first light receiver by a central angle of less than <NUM>°, wherein the first baffle (<NUM>) is located between the first light emitter and the second light emitter;
a second baffle (<NUM>) extending from the periphery of the sensing chamber toward the middle portion and disposed between the second light emitter (<NUM>) and the first light receiver (<NUM>), wherein the second baffle blocks part of a background light comprising a scattered portion of light emitted by the second light emitter that would otherwise be incident on the first light receiver; and
a third baffle (<NUM>) disposed at the outer side of the first light receiver (<NUM>), an inner end of the third baffle extending toward the radial direction of the first light receiver.