JP2880751B2 - Photoelectric smoke detector - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric smoke detector for detecting smoke by receiving light scattered by smoke particles of light from a light emitting element.

[Prior Art] A photoelectric smoke detector is provided with a smoke introduction chamber, in which a light emitting element and a light receiving element are arranged at a position where light from the light emitting element is not directly received by the light receiving element. 2. Description of the Related Art There is a type in which smoke is sensed by receiving light scattered by a light emitting element due to smoke particles flowing into a room by a light receiving element.

By the way, in this type of photoelectric smoke detector, in order to prevent malfunction due to transient noise or the like, the light emitting element is periodically intermittently lit, and smoke is continuously emitted plural times (for example, three times). Some of them perform a so-called accumulation operation of outputting a fire signal when detected.

[Problems to be Solved by the Invention] When the above-mentioned photoelectric smoke detector performs an operation check, by increasing the amount of light emitted from the light emitting element, for example, the so-called stray light component such as irregularly reflected light due to the inner wall of the smoke introduction chamber is increased. Then, an operation check is performed by causing the light receiving element to receive the same amount of light as when smoke is present and outputting a fire signal.

However, in the case of the storage operation type photoelectric smoke detector, a fire signal is not output unless a smoke detection output is obtained a plurality of times in the same manner in the above-described operation check. was there.

The present invention has been made in view of the above points, and an object of the present invention is to provide a photoelectric smoke detector in which an operation check does not take much time.

[Means for Solving the Problems] In order to achieve the above object, the present invention outputs a fire signal when a smoke detection output is generated once at the time of operation check.

[Operation] According to the present invention, a fire signal is output when the smoke detection output is obtained once during the operation check as described above, so that the operation check does not take much time.

FIG. 1 and FIG. 2 show an embodiment of the present invention. The photoelectric smoke detector according to the present embodiment is connected to a sensor line 1 composed of a pair of signal lines L and C to which a constant voltage is applied. In the case of a distributed processing type, a fire signal is sent to a repeater in a current mode, and light from a light emitting element (for example, LED) 1 is directly sent to a light receiving element (for example, , SPD)
The light-emitting element 1 and the light-receiving element 2 are arranged so as not to be received by the light-receiving element 2, and the light-receiving element 2 receives the scattered light of the light-emitting element 1 due to the smoke particles flowing into the smoke introduction chamber to sense the smoke. Further, in this photoelectric smoke sensor, the light emitting element 1 is intermittently made to emit light by the light emission control unit, and the signal processing unit determines that a fire has occurred when smoke is detected a plurality of times in succession. What is the light emission control unit and the signal processing unit
The IC (AK0129) 5 is integrally formed. The input of this photoelectric smoke sensor is provided with a diode bridge DB so that it can be connected to the detector line 1 in a non-polar manner, and a switching circuit configured using SCRQ ₁ connected between the outputs of the diode bridge DB. 3. The fire signal is sent to the fire receiver by short-circuiting between the detector lines 1 by 3. Also, in this photoelectric smoke detector, the transistor applied to the detector line 1
A power supply circuit 4 composed of Q ₂ , Q _{3, a} Zener diode ZD and the like creates a power supply for the IC 5. FE voltage that charges the capacitor C ₇ via the resistor R ₁₄ by the output of the power supply circuit 4 to the light emitting element 1 is supplied as a power supply, which are connected in series
When the TQ ₄ is turned on and off by the oscillation output L _out which is the output of the light emission control unit, the light emitting element 1 emits light intermittently as shown in FIG. ). Note that the current limiting resistor R ₁₁ of the light emitting element 1 by connecting a thermistor TH in parallel, are to prevent the quantity of light from the light emitting element 1 due to variations in the ambient temperature fluctuates. When the light receiving amount of the light receiving element 2 exceeds a predetermined level a plurality of times (for example, three times) continuously as shown in FIG.
Smoke detection output SMOK which becomes high level as shown in Fig. (D)
E is equipped. When the smoke detection output SMOKE goes high, SCRQ _{1 of the} switching circuit 3 conducts and sends a fire signal to the fire receiver in the current mode.

The above is the basic circuit configuration of the photoelectric smoke detector and its operation description. In this embodiment, the following configuration is provided for checking the operation. That is, a reed switch S that is turned on by approaching a magnet when performing an operation check
When this switch S is on, one input goes high, the other input receives an oscillation output L _out, and an AND circuit A _{1. When} this AND circuit A ₁ goes high, a resistor R FETQ be connected in parallel ₁₆ to the current limiting resistor R _11
5 and have. Further, the IC5 is provided with an output _Tout which becomes a high level when the amount of scattered light received by the smoke particles of the light receiving element 2 exceeds a predetermined level. , and a aND circuit a ₂ of the output T _out is input to the other input, the aND circuit respectively diode D ₁ and the output and the smoke output sMOKE of a _2,
Is input to the switching circuit 3 via the D _2.

With the above circuit, the photoelectric smoke detector operates as follows at the time of operation check. That is, when the reed switch S is turned on to check the operation, the AND circuits A ₁ , A
_{One of the two} inputs goes high. When the oscillation output L _out occurs in this state, the output of the AND circuit A ₁ becomes high level, the resistor R ₁₆ is connected in parallel to the current limiting resistor R _11, Therefore light emission quantity of the light emitting element 1 is increased. Thereby, the stray light component is increased, and a pseudo fire occurrence state is created. That is, beyond a predetermined level the amount of received light increases by the stray light component of the time the light receiving element 2 is output at this time T _out
Becomes high level as shown in FIG. 2 (c). Thus, the output of the AND circuit A ₂ becomes high level, the fire signal is output from the switching circuit 3. As described above, in this embodiment, when the amount of light received by the light receiving element 2 once exceeds a predetermined level, a fire signal is output immediately. Therefore, even in the case of a photoelectric smoke sensor that performs a so-called accumulation operation, it takes time to check the operation. There is an advantage that this does not occur.

By the way, there is a composite type fire detector which combines a heat detection function with a photoelectric smoke detector which detects smoke from light scattered by such smoke particles. In this type of fire detector, the smoke detector and the heat detector are completely independent, and the signal processing circuit requires signal processing according to the outputs of both detectors, so the circuit configuration is complicated. However, there is a problem that the shape becomes large.

Therefore, in such a case, as shown in FIG. 3, a bimetal 6 for sensing the ambient temperature is attached to the outer surface of the outer shell 9 having the smoke introduction chamber 8 formed therein, and the bimetal 6 is integrally transmitted to the bimetal 6. A rod 7 is attached, and the transmission rod 7 can be moved back and forth within a smoke sensing area (shaded area in the figure) between the light emitting element 1 and the light receiving element 2 formed in the smoke introduction chamber 8 according to the displacement of the bimetal 6. good. In this way, when the ambient temperature rises to a predetermined temperature or higher and the bimetal 6 is displaced to the state shown by the broken line in FIG. 3, the transmission rod 7 is inserted into the smoke sensing area, and scattered light is transmitted by the transmission rod 7. As a result, the amount of light received by the light receiving element 2 increases, so that the ambient temperature is converted into a smoke generation state. Therefore, a part of the smoke sensing unit and a part of the heat sensing unit can be used, and a common signal processing circuit can be used. Therefore, the circuit configuration is simplified and the shape is reduced. In addition, the smoke flows through the smoke inlet 10 formed on the peripheral surface of the case 9.
, And flows into the smoke introduction chamber 8.

[Effects of the Invention] As described above, the present invention outputs a fire signal when a smoke detection output is generated once at the time of operation check. Therefore, a fire signal is not output until a pseudo increase in the amount of light received by the light receiving element occurs, so that the time required for the operation check can be reduced.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of one embodiment of the present invention, FIG. 2 is an explanatory diagram of the operation of the embodiment, and FIG. 3 is a cross-sectional view of a photoelectric smoke detector to which a heat sensing function is added. 1 is a light emitting element, 2 is a light receiving element, and 5 is an IC.

Continuing from the front page (72) Inventor Akira Nagaoka 1048 Kazuma Kadoma, Osaka Prefecture Matsushita Electric Works, Ltd. Document JP-A-59-46841 (JP, A) JP-A-53-3880 (JP, A) JP-A-54-83878 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) G08B 17/107

Claims (1)

(57) [Claims] 1. A light-emitting element and a light-receiving element are arranged in a position where light from a light-emitting element is not directly received by a light-receiving element in a smoke introduction chamber, and the light-emitting element is periodically intermittently illuminated, and is introduced into the smoke introduction chamber. In a photoelectric smoke sensor that outputs a fire signal when smoke is detected multiple times consecutively by receiving light scattered light of the light emitting element by smoke particles with a light receiving element, increasing the light emission amount of the light emitting element Increase the amount of stray light in the smoke introduction room, make the light-receiving element receive the same amount of light as when smoke is present, perform an operation check, and at the time of operation check, output a fire signal when a smoke detection output occurs once. A photoelectric smoke detector characterized by comprising: