Smoke detector

The present invention relates to a smoke alarm for detecting smoke especially for use in a home environment.

A typical conventional smoke alarm is battery powered and includes a housing consisting of a mounting plate and / or base and a removable cover. The housing mounting plate is designed to be attached directly to a flat surface, such as a ceiling, with screws or the like that pass through the base of the alarm. A removable cover is provided, or a cover that swivels sideways to gain access to the inside of the housing for battery replacement. Alarm components are typically mounted in a printed circuit (PCB) enclosure. The battery is typically mounted by simply pressing on the terminal insert. Along with the battery, one or more sensors are / are typically mounted on one side of the PCB along with other alarm components, including the loudspeaker and control circuits. The other side of the PCB is usually attached to the base.

The base and / or removable cover are equipped with ventilation holes to allow smoke and / or other air pollution to enter for detection by the sensor (s). In addition, when the alarm is a multi-functional device, one or more buttons may be provided for various alarm functions and operations. This type of alarm is described in WO 2008/125834 A2.

The problem with these types of alarms is that the presence of components on the PCB, as well as other features in the alarm housing, interfere with the flow of smoke to the sensor. One consequence is that the time it takes for an alarm to detect smoke may vary depending on the direction in which the smoke enters the alarm. A solution to this problem has been proposed in WO 01/43097. This solution includes placing the sensor on the opposite side of the PCB to other components of the device and placing the PCB in the housing so that part of the sensor protrudes from the housing towards the ceiling mounting plate. Attachments are provided to secure the housing to the ceiling mounting plate so that the space is between the ceiling mounting plate and the housing, providing a flow path for smoke passage. Smoke flowing along this flow path can flow around the mountings and enter the sensor.

The problem with this solution is the increase in the complexity of the housing design and the need to fix components on both sides of the PCB. This increases production costs and results in a massive and more conspicuous alarm profile.

Other known alarms are disclosed in US 5,751,218 and WO2008 / 011413. US 5,751,218 discloses a smoke detector having a detection chamber that allows air to circulate. The housing defines a window through which air circulates to and from the detection chamber. The window height is approximately the same as the chamber and the caged blade is in the window. The configuration conducts air currents typically created by fires at the ceiling so that smoke easily flows into the detection chamber. WO2008 / 011413 discloses a smoke detector having a particle detector comprising: a light source, an optical transducer and a controller. The controller is connected to the light source and optical transducer, and is configured to reject all signals except those to which the light source contributes.

The object of the present invention is to provide an alarm that is even more sensitive to smoke entering the device around its periphery, is more narrow and has a reduced production cost.

According to the present invention, there is provided a smoke detection device comprising: a housing having ventilation openings allowing said smoke to enter the housing; a sensor chamber housed in the housing, said sensor chamber is defined by a first part of the chamber and a second part of the chamber and has ventilation holes to allow said smoke to enter the sensor chamber; a sensor element mounted in the sensor chamber; an alarm circuit comprising a detection element for detecting said smoke upon detection by a sensor element; and a printed circuit (PCB) supported by parts of the chamber so that it is partially sandwiched between the first part of the sensor chamber and the second part of the sensor chamber, such that its edge extends partly to said sensor chamber to divide the sensor chamber into two parts, one placed above the PCB and the other below the PCB, where said PCB has an alarm circuit and sensor element attached to it and the sensor element is mounted on, close or adjacent to said edge.

Ventilation holes may be arranged around the periphery of the housing to determine a substantially planar flow path for smoke passage through the housing. In this case, the sensor chamber is preferably equipped with ventilation holes lying at least partly in the planar flow path, whereby smoke entering the housing through the housing ventilation holes can flow along the planar flow path and into the sensor chamber. The PCB can be placed in parallel and adjacent to said planar flow path such that one of said parts of the chamber lies substantially in the planar flow path and the other part of the chamber is displaced with respect to the planar flow path. The second part of the sensor chamber can be substantially solid so that smoke enters the chamber through ventilation holes that lie in the planar flow path.

The alarm housing preferably has an upper and a lower part that connect together to provide a closed space for the battery, loudspeaker, and, where the upper and lower part are of a size such that the attachment of the battery and the loudspeaker to the upper part is such that they lie substantially outside planar flow path of the housing. The outer surface of the housing, and the lower part in particular, is preferably profiled to have a discrete narrow profile.

The sensor element may include a transducer emitting radiation to direct the radiation to the sensor chamber and a radiation detect transducer to detect radiation reflected from smoke present in the sensor chamber.

According to the present invention, there is also provided a sensor chamber assembly for use in the device according to the invention, the sensor chamber assembly comprises: a sensor chamber defined by the first chamber part (22) and the second chamber part (26) and ventilation holes for allowing smoke to enter the assembly sensor chambers; a sensor element mounted in the sensor chamber; an alarm circuit comprising a detection element for detecting said smoke upon detection by a sensor element; and a printed circuit (PCB) supported by parts of the chamber so that it is partially sandwiched between the first part of the chamber and the second part of the chamber, such that its edge extends partly to said sensor chamber to divide the sensor chamber into two parts, one located above the circuit printed and the other below the printed circuit, where said PCB has an alarm circuit mounted thereon and the sensor element is mounted on, close or adjacent to said edge.

According to the present invention, there is also provided a method of calibrating a sensor chamber assembly as defined above, the method comprising the step of simultaneously calibrating multiple or multiple of said sensor chamber assemblies prior to installation in their respective housings together with their respective batteries and speakers.

The alarm circuit, which may include a microprocessor for controlling the operation of the alarm, is wired to the PCB and connected to the battery and speaker in a manner known in the art.

The housing can be formed in the upper and lower parts, the "upper" refers to the part that is placed closer to the ceiling after installation. The upper and lower parts join together to provide a closed space to accommodate the alarm components. The upper part is preferably equipped with an interlocking element for locking meshing with corresponding elements located on the mounting plate, which in turn has accessories to facilitate its attachment to the ceiling. So, the alarm is attached to the ceiling by first attaching the mounting plate to the ceiling and then locking the housing to it.

The upper part may also include a mounting surface for the battery and alarm speaker as well as for the second part of the sensor chamber. The lower part of the housing contains an aesthetically pleasing contoured cover to cover the alarm components. Ventilation holes that define a planar flow path are arranged around the peripheral periphery of the upper portion.

The mounting plate may have an upper surface and a through hole for receiving a fastening such as a screw for fastening said mounting element to a generally flat surface. The through hole may be elongated and have an enlarged part for the passage of the fastening head through the through hole, the narrowed part for holding said head and the neck portion between them.

Embodiments of the present invention have the advantage that the amount of PCB required is reduced because the battery and speaker are attached to the housing, the PCB is generally reserved for the components of the alarm circuit. The PCB is effectively "sandwiched" between the first and second part of the sensor chamber so that the secondary ventilation holes are on one side and the fixed wall of the chamber is on the other side. Because the PCB extends only partially into the sensor chamber, the sensor or sensors may be close to or in the smoke flow path along the planar flow path. This results in reduced production costs in terms of materials and structural complexity. PCB sanding between two halves or parts of the sensor chamber forms a sensor-PCB chamber assembly that is easier to manipulate during production than prior art systems that assemble the PCB separately from the sensor or sensor chamber. What's more, providing alarm circuits on the sensor-PCB chamber assembly enables calibration of more assemblies simultaneously in the calibration device resulting in improved production. Embodiments of the present invention simplify the alarm that combines indifferent directional dependence and effective breathing through a wide unfettered plenary smoke flow from all directions while having a discreet narrow profile.

The invention will now be illustrated by means of a description of an example of the present invention, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of an alarm according to an embodiment of the present invention in a bottom view when mounted on the ceiling;

Figure 2 is a perspective view of the upper part of the alarm housing of Figure 1 showing the mounting plate;

Figure 3 is a perspective view of the upper part without mounting plate;

Figure 4 is a view of the interior of the upper housing to show the attachments for the alarm components;

Figure 5 is the view of Figure 4 with the addition of a part of the sensor chamber;

Figure 6a is a view of Figure 5 with the addition of a distal portion of the sensor chamber, printed circuit and battery;

Figure 6b is a view similar to figure 6a showing half of the removed sensor chamber; and

Figure 7 is a side view of the alarm of the previous figures with the main vents of the upper part removed to show the secondary vents of the sensor chamber and the flow path for smoke passing through the device.

Referring to the drawings, Figure 1 is a perspective view of a preferred form of alarm 1 according to the invention. The alarm is suitable for attachment to a flat surface such as a wall or ceiling but is described herein with respect to its attachment to the ceiling. The view of the alarm shown in Figure 1 is from below when it is mounted on the ceiling. Certain aspects of the present invention to illustrate include the detail of the alarm design and will now be described in detail.

Figure 2 shows alarm 1 on the other side, namely the ceiling mounted side. Alarm 1 includes a housing and a fastening element for attaching the housing to the ceiling. The fastener is in the form of a mounting plate 2, which is generally round and planar. The housing has an upper part or housing element 3 and a lower part or housing element 4. The terms upper and lower are relative and depend on the orientation of the alarm, but are used here in the sense that applies when the alarm is attached to the ceiling.

The illustrated alarm is round with a dome design for an aesthetically pleasing appearance.

The lower housing element 4 has a generally circular, dome structure with a substantially smooth outer surface 90 and a rim 92. When the alarm is attached to a flat surface, this housing element 4 will be the farthest from the flat surface. When attached to the ceiling, for example, the housing element 4 will face the floor. Element 4 contains the "function test" and "silence" 5 buttons (the only button provided in this alarm design) which is located on or near the top of the dome. The housing element 4 also has a ventilation opening 6 in the dome surface, just below the button 5. A loudspeaker or signaling device (see Figures 3 to 7) is attached adjacent to the ventilation openings 6 inside the alarm housing. The upper housing 4 is also equipped with an indicator light 7 indicating the functional states of alarm 1.

The upper housing element 3 is generally round and comprises a generally planar base in the form of a bottom plate or base 8 with a sidewall 50 at an outward and downward angle extending throughout the entire periphery. The side wall 50 has a plurality of holes 9 arranged around the perimeter of the base plate 8. They are preferably evenly angularly spaced along side wall 50, although any suitable arrangement may be used, and provided for smoke or pollution entering the alarm 1 from any direction.

The lower housing element 4 and the upper housing element 3 are preferably latched together by means of gripping elements preferably in the form of cooperating projections and receptors. Figures 4 and 5 show the locators 10 and projections 11 positioned around the perimeter of the housing element 3 for meshing with the corresponding receptors (not shown) in the lower housing element 4. In this embodiment, the protrusion and receptor assemblies are arranged around the respective surfaces of the housing components 3 and 4 such that the two housing components will only snap together. The internal features of the alarm are positioned and configured to prevent incorrect assembly (Poke Yoke) in a manner known in the art. As can be seen from Figure 4, the protrusions 11 are formed with a hook end part. It snaps into place with the arm formed on the corresponding receptor in the lower housing element 4.

When the housing components 3 and 4 are latched together, a space is defined between them in which the alarm circuits, loudspeaker or siren and other alarm components can fit. Suitable attachment means are provided for their attachment to the upper housing element 3 as will be described in more detail below with reference to Figures 4-6.

The mounting plate 2 shown in Figure 2 is provided with holes 12a and 12b to facilitate fixing the plate 2 to the wall or ceiling with screws. The upper housing element 3 after detachment from the mounting plate 2 is shown in Figure 3. The base plate 8 of the housing element 3 is equipped with hook elements 13 that lock with corresponding catches (not shown) located in the mounting plate 2. The angled cut-outs 14 are in connection with the catches in the mounting plate for receiving hook elements 13, whereby the upper housing element 3 can be attached to the mounting plate 2 after the latter is attached to the wall or ceiling.

Figure 4 is a view of the interior of the upper housing 3 and is equipped with battery supports 15a and 15b for supporting the battery 16 (see Figure 6). The battery supports 15a and 15b are arranged in a radial direction such that they do not interfere with smoke or dirt entering the upper housing 3 from the direction of arrow A. The piezoelectric loudspeaker 17 is designed to generate an audible alarm when smoke or pollution has been detected by alarm 1.

Figure 5 shows the location of the first part of the chamber 22 of the sensor chamber housed on the base 23 of the upper housing 3. This can be done by a locking system between a pair of hook projections (not shown) located on the first part of the chamber 22 and the corresponding holes (not shown) located in attitude 23. The first part of the chamber 22 comprises a substantially circular circumferential wall formed of distal elongated elements comprising two groups of elements 24a and 24b, respectively. These groups of elements 24a and 24b are arranged and narrowed inside the chamber portion 22 to define the ventilation holes to provide a flow path for smoke or impurities entering the interior of the alarm 1 through the main ventilation holes 9 of the upper housing 3 from any direction in the base plane 23. One group of elements 24a is directed substantially inside the upper housing 3 and the other group is directed essentially outwards and have different profiles from each other.

In this embodiment, the diode sensor 25 is shown in one (26a) of a pair of collimator housings 26a and 26b. The emitter diode (not shown) is housed in the second of the 26b collimator housings. The diode sensor 25 and the diode emitter are directed towards the center of the first part of the chamber 22 to optically detect the presence of smoke or other pollutant entering the chamber. The profile of the first group of elements 24a narrows inward towards the center of the sensor chamber 22. The profile of the second group of elements 24b includes inwardly narrowed portions 27a and outwardly directed vent holes 27b that are configured to trap external light such that the light does not shine directly on the front of the sensor and interferes with the sensor 25 or the emitter. The partition or disc 28 is located in the center of the sensor chamber 22 to block direct light transmission between the diode sensor 25 and the emitter. The diode emitter emits light that is intended to be reflected in the direction of the sensor diode by the presence of smoke in the sensor chamber. Disc 28 includes a double blade system to prevent contaminating deposits settling on one of the blades causing erroneous reflection.

Figure 6a shows the battery 16 in place on the battery supports 15a and 15b. They hold the battery 16 in a distant position relative to the base 23 of the upper housing 3 so that there is sufficient space to allow smoke or other contaminants entering through the vent holes 9 from the direction of arrow A to enter the sensor chamber.

Figure 6a shows a second part of the chamber 26 fixed on the first part of the chamber 22. The second part of the chamber 26 has a wall that is substantially solid and thus defines a closed chamber above the first part of the chamber 22 that is open to the flow of smoke or other contamination by the alarm.

The first and second parts of chamber 22 and 26 together form the chamber of the alarm sensor 1. The sensor chamber defines the two parts of the chamber defined by the first and second parts of the chamber 22 and 26 respectively. The printed circuit (PCB) 29 is located between the first and second parts of the chamber 22 and 26 so that it extends partially into the sensor chamber. The PCB may advantageously be compressed or "sandwich" between the first and second parts of the chamber. This is seen from Figure 6b, which is similar to Figure 6a, except that the second part of the chamber 26 has been removed to expose the interior of the sensor chamber and the location of the PCB 29 in relation to the first part of the chamber 22. The emitter and receiver / sensor 25 diodes are mounted on or adjacent to the leading edge 30 of the PCB 29, which leading edge 30 may extend substantially to half (in this example not quite half) of the sensor chamber thereby separating the first and second parts of the chamber 22 and 26. The leading edge 30 may be substantially aligned with the diameter of the sensor chamber and may be substantially C-shaped. By attaching collimator housings 26a, 26b (which support the emitter and receiver diodes 25 respectively) at or near the free ends of the C-leading edge, the emitter and receiver diodes 25 are directed towards the center of the sensor chamber 22. PCB 29 supports the alarm circuits 32 on one its side that faces / extends into the lower housing 4 and is outside the path of smoke or other impurities through the upper housing 3. The PCB 29 itself is attached to the first portion of the chamber 22 so that it lies in a plane parallel to the base 23 but is distant from it so as not to interfere with the flow of smoke or other contaminants through the upper housing 3. In fact, the location of the PCB may help direct the detected materials into sensor chamber.

This arrangement allows the emitter and sensor to be placed in the sensor chamber (as opposed to through the window) and secured to the PCB. This arrangement allows simplification of production along with high reliability. Because the sensors are in the sensor chamber, they are less likely to be affected by anything outside the light chamber and by integrating them on the PCB and sanding it between the two halves, the PCB can be fully tested before insertion and assembly is simple.

Figure 7 is a side view of the alarm 1 with the main upper ventilation holes 9 removed, showing the secondary ventilation holes 34 of the first chamber portion 22 of the sensor chamber and the flow path for smoke passing through the device. The flow path is indicated by arrows C - which is essentially a planar flow path, whereby smoke or other contaminants entering the housing through the main ventilation holes of the upper housing 3 can flow along the planar path and into the sensor chamber through its secondary ventilation holes. The construction of the embodiment described above provides improved directivity from all directions of the alarm for the flow of smoke or other contaminants that may fall on the alarm. This leads to improved response times. Furthermore, alarms implementing the present invention, such as the one described above, are simpler to manufacture and more economical in materials. Providing a sandwich PCB 29 between the first and second parts of the chamber 22, 26 allows for easier calibration because smoke detection electronics can be easily operated outside the housing.

LAW FIRM ATTENTION "BELLEPAT"

Izabela Szych ulska-Hawranek ul Słowackiego 44, 37-700 Prz * 'i&gt; vśl tel. (016) 7C2-37-77 fax: (016).: 75-32-87 mobile phone (0608) 503-081 e -maii <a href="mailto:bsllepat@op.pl">bsllepat@op.pl</a> NIP: 795-207-16-72 REGON: 1803505: 6

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REFERENCES CERTIFIED MA Izabela SMuilska-HawTml entry no. 31S2