CN1237339C - Vertical backward scattering type photoelectric smoke detector - Google Patents

Abstract

The invention relates to a vertical backscattering photoelectric smoke detector, which mainly includes: a detection chamber composed of a light-shielding window (1) and a base (3), an emission light path composed of a light emitter (2) and a light emission lens (4) , the light-receiving lens (6) and light-receiving lens (5) form the light-receiving path, and its characteristic is: the axis of the light that light-transmitter (2) emits and the center of light-receiving lens (6) and light-receiving lens (5) receive light The angle formed by the plane defined by the intersection of the axes and the plane where the circuit board (8) is located is in the range of 70° to 110°. The unique vertical structure of the detector of the present invention effectively utilizes the space of the detection room, reduces the volume, and weakens the directionality. In the case of limited space in the detection room, it realizes a smaller scattering angle and better responds to various types of smoke. And generate enough output signal.

Description

Vertical Backscatter Photoelectric Smoke Detector

technical field

The present invention relates to a photoelectric smoke detector, and more specifically relates to a vertical backscattering photoelectric smoke detector for fire alarm protection.

Background technique

According to the principle of optical reflection, photoelectric smoke detectors can be divided into forward scattering type, backward scattering type and bidirectional scattering type combining front and rear. The angle α between the axis of light emitted by the light emitter and the axis of light received by the light receiver: 90°<α<180°, called forward scattering type; the axis of light emitted by the light emitter and the light received by the light receiver The angle α between the axes: 0°<α<90°, which is called backscattering type.

The intersection of the transmitting optical path of the optical transmitter and the receiving optical path of the optical receiver is called the detection area. The size of the detector depends largely on the maximum size of the detection area. In the backscattering photoelectric smoke detector, this effect is very large, and when the scattering angle is smaller, the vertical space requirement of the detection room is larger, as shown in Figure 3, where the scattering angle in Figure 3(b) is relatively As shown in Fig. 3(a), it is smaller, so the size of the "D" direction of the detection area is relatively large, and the required vertical space of the detection room is relatively large.

The backscattering photoelectric smoke detectors in the prior art all belong to the horizontal structure from the structural point of view. It is characterized in that the angle formed by the plane (A) formed by the central axis of the light path of the light transmitter and the light path of the light receiver and the plane (B) where the circuit board is located is usually 0°±20°. For example, the structure described in US Pat. No. 4,397,557, the backscattering photoelectric smoke detector with this structure has a large volume. To reduce the volume of the detector, it is necessary to increase the scattering angle, such as the detector described in European patent EP0880118ZAZ, which is the case. For backscattering photoelectric smoke detectors, the smaller the scattering angle, the greater the response output to smoke, especially the better response characteristics to black smoke. The better the sensitivity to different types of smoke, in order to improve the response performance of the photodetector and reduce the scattering angle, its volume must be increased; in order to reduce the volume and increase the scattering angle, the response performance of the detector must be weakened. Another disadvantage of the horizontal backscattering photoelectric smoke detector is poor directivity. The position of the optical transmitter and optical receiver will block the entry of smoke, and the distance between them is very close, making the space between them narrow, which also hinders the entry of smoke, while the channel in other directions is unblocked, and the smoke is very easy to enter. Easy, this makes the sensitivity of the detector to smoke inconsistent in different directions, resulting in poor directivity of this photoelectric smoke detector.

The purpose of the present invention is to provide a vertical backscattering type photoelectric smoke detector, which can effectively and fully utilize the space of the detection chamber, so that a smaller detection chamber can accommodate a longer detection area, thereby improving the efficiency of the present invention. detection performance.

Contents of the invention

The purpose of the present invention is achieved through the following technical solutions.

In the vertical backscattering photoelectric smoke detector of the present invention, the plane (A') formed by the central axis of the emitting light path of the light transmitter and the central axis of the receiving light path of the light receiver and the plane (B) where the circuit board is located ') as shown in the figure, which is 90°±20°. The structural design of the present invention makes full use of the space in the detection chamber, so that a smaller detection chamber can accommodate a longer detection area. The longitudinal section of the detection chamber of the present invention is rectangular, and the longest direction of the detection area is close to the diagonal direction of the rectangular section, which can improve the space utilization rate of the rectangular section. The longest dimension of the longitudinal section of the detection area is on the diagonal of the longitudinal section of the detection chamber, thus making full use of the space in the detection chamber. At smaller scattering angles, the size of the maze is also smaller. That is to say, in the case of a certain detection room space, the scattering angle can be designed to be smaller to improve the detector's influence output on smoke. The scattering angle of the present invention can be at least 40°, that is, the range of backscattering angle can be 40°-90°, and the desired angle can be selected according to needs.

Compared with the existing horizontal backscattering photoelectric smoke detector, the vertical backscattering photoelectric smoke detector of the present invention has the advantage of good directivity. Only the light emitter slightly blocks the smoke in the flue; the light receiving part is under the flue, which does not prevent the smoke from entering the detection room, and there is no narrow gap between the light emitter and the light receiver, so it will not affect The entry of smoke makes the detector uniform in sensitivity to smoke in all directions. In addition, in the vertical structure, the optical receiver is very close to the circuit board, so the planar patch device can be used to reduce the number of repair soldering devices in the manufacturing process, reduce the welding workload, and improve production efficiency. Furthermore, the optical receiver is surface-mounted on the circuit board together with the receiving circuit, and it is easy to design an electromagnetic shielding part for the receiving circuit and the receiving part.

Description of drawings

Describe the present invention in detail below in conjunction with accompanying drawing.

Fig. 1 (a) is the schematic diagram of the angle α between the axis of the light emitted by the light emitter of the forward scattering photoelectric smoke detector and the axis of light received by the optical connector;

Fig. 1 (b) is a schematic diagram of the angle α between the axis of the light emitted by the light emitter of the backscattering photoelectric smoke detector and the light axis of the light receiver;

Figure 2(a) is the plane (A) formed by the central axis of the optical transmitter optical path of the horizontal backscattering photoelectric smoke detector and the central axis of the optical receiver optical path and the plane (B) where the circuit is located Angle diagram;

Figure 2(b) is the plane (A') formed by the central axis of the light emitting path of the light emitter of the vertical structure backscattering photoelectric smoke detector and the central axis of the receiving light path of the light receiver and the plane where the circuit board is located Schematic diagram of the angle formed by (B');

Fig. 3 a and Fig. 3 b respectively show the dimension of " d " direction of the detection area of the scattering photoelectric sensor of different scattering angles;

Fig. 4 shows the relational diagram of the detection zone (the part of drawing shade among the figure) and the detection chamber that comprises detection zone of vertical backscattering type photoelectric sensor;

Fig. 5 is a structural sectional view of a vertical backscattering photoelectric smoke detector.

Fig. 6 shows the cross-sectional view of the light-receiving part that replaces the planar receiving tube and the lens with the plug-in receiver;

Fig. 7 shows that the patch emitting tube and the light guide column replace the light emitting part composed of the plug-in receiving tube and the lens.

Detailed ways

Taking the vertical backscattering photoelectric smoke detector with a backscattering angle of 45° as shown in FIGS. 5-7 as an example, the embodiments of the present invention will be described in detail below;

As shown in Fig. 5, the light-shielding window 1 and the base 3 form a dark room, which is called a detection room. The blades on the shading window 1 form an optical trap, which neither hinders the entry of smoke, but also blocks the external ambient light, making the interior a dark room to prevent the interference of ambient light. absorbing background light. The base 3 forms a bracket to support the transmitter and the shading window, and it also acts as a fixation to fix the circuit board; in addition, the structure above it forms a receiving channel, and the received light is irradiated to the receiver through this channel.

The emitter 2 is arranged on the upper part of the base 3, and the light emitted by it is refracted by the lens 4, passes through a sawtooth emitting chamber formed by the light-shielding window 1 and the base 3, and enters the detection chamber. The angle formed by the central axis of the light emitted by the transmitter 2 and the plane where the circuit board is located is 0°±5°. In order to simplify the installation, the emitting part can also be replaced by the patch emitter 11 and the light guide column 10. The path of the light emitted from the light guide column is the emission light path, and its central axis coincides with the original axis. The central axis of the emission light path can also have other orientations, for example obliquely upward.

The receiver 5 is surface-mounted on the circuit board 8 and receives external light through the receiving lens 6 . The plane where the lens 6 is located is perpendicular to the receiving light path. The optical axis center of the receiving optical path intersects with the optical axis center of the emitting optical path at 45°±5°, and they are in the same plane, and the angle formed between this plane and the plane where the circuit board is located is 90°±5°. For backscattering photoelectric smoke detectors, the smaller the scattering angle, the greater the response output value to smoke, this angle belongs to the smaller backscattering angle, and the larger the response value to smoke. It is not sensitive to the color of smoke, and has similar output to smoke of different colors. The second time, the receiving part is under the smoke inlet of the shading window, which will not block the entry of smoke like a horizontal maze, and improve the directionality of the detector. It can be designed to any angle within the range of 0°±90° as required. The receiver 5 of the present invention adopts a plane surface-mount receiving device, which reduces the number of devices for repair welding and improves production efficiency. The plane surface mount receiver 5 of the present invention is also replaced by a plug-in receiver 9, whose central axis coincides with the original axis.

The longest dimension "d" of the detection area formed by the intersection of the emission path and the reception path of the vertical backscattering photoelectric smoke detector of the present invention is close to the diagonal direction of the detection chamber section, making full use of the limited space of the detection chamber Space, saving 25% of the space. In the case of limited space in the detection chamber, the scattering angle can be made smaller. In addition, in order to prevent the influence of dust and prevent the background light from being too high, a certain gap is left between the detection area and the side wall and top wall of the detection chamber. The baffle 7 effectively blocks other stray light from entering the receiver, reducing background light.

Claims (4)

1. Vertical backscattering photoelectric smoke detector, which includes a detection chamber composed of a shading window (1) and a base (3), an emission optical path composed of a light emitter (2) and a light emission lens (4), and a light receiving The receiving optical path formed by the lens (6) and the light receiver (5) is characterized in that: the central axis of the light emitted by the light transmitter (2) intersects with the central axis of the light received by the light receiving lens (6) and the light receiver (5) to determine The angle formed by the plane of the circuit board (8) and the plane where the board body of the circuit board (8) is located is in the range of 70°-110°, and the angle formed by the central axis of the emitted light path and the light central axis of the received light path is the backscattering angle. 2. The vertical backscattering photoelectric smoke detector according to claim 1, characterized in that: the detection area formed by the intersection of the emitting light path and the receiving light path is located in the detection chamber, and the formed scattering angle is in the range of 40° to 90° . 3. According to the vertical backscattering type photoelectric smoke detector according to claim 1, it is characterized in that: the light emitting part made up of light emitter (2) and light emitting lens (4) can be made of patch emitter (11) and Light guide column (10) replaces. 4. The vertical backscattering photoelectric smoke detector according to claim 1, characterized in that: the receiving part composed of the light receiver (5) and the light receiving lens (6) can be replaced by a plug-in receiver (9).

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