JPS60185141A - Smoke detecting apparatus - Google Patents

Abstract

PURPOSE:To make it possible to acknowledge accurate operation regardless of presence or absence of smoke, by computing the outputs of a scattering optical body before and after the change in the amount of light emission, and comparing the result with a reference value. CONSTITUTION:A scattering light receiving body 14 receives the background at a certain amount of light emission and the amount of light of the sum of the background and the scattered light due to smoke if the smoke is present. The outputs, which are amplified by an amplifier 15, are sampled and held in a memory 22. Then the amount of the previous light emission is made to be (k) times. The background and the amount of the scattered light by the smoke if it is present are both increased to (k) times. The total amount of the incident light to the light receiving body 14 becomes also (k) times. The difference or ratio between the previously sampled and held values and the result is obtained by an operaor 23. Its output becomes (k-1) times and the ratio becomes (k). Both values are the predetermined values. Whether these values are within the voltage range, which is determined by the reference voltage 25, or not is judged by a window type comparator 24. The result is inputted to an operation-acknowledging output circut 26 and the operation is acknowledged.

Description

[Detailed description of the invention] The present invention relates to a photoelectric scattering type smoke detector.

In particular, the present invention relates to a smoke detection device that can confirm whether or not a sensor is operating normally.

In general, photoelectric scattering type smoke detectors have a light emitting body inside a structure that allows smoke to easily enter and blocks external light, and the light emitted from the light emitting body is not directly received. It is composed of a scattering photoreceptor that receives scattered light and a scattering photoreceptor that receives the scattered light, and further includes an electronic circuit that controls these light emitting photoreceptors.

In conventional photoelectric scattering light type smoke detection, a light emitter.

There is a configuration shown in FIG. 1 that confirms whether the photoreceptor itself and the control circuit are operating normally. In FIG. 1, the scattered light receiver 4 receives the scattered light when the light from the light emitter 3 is scattered due to the presence of smoke. However, even when there is no smoke, the light from the light emitter is reflected by the surrounding walls and enters the light receiver as a bank ground. When operating as a photoelectric scattering smoke detector,
The amount of light incident on the photoreceptor is the sum of the background and light scattered by smoke. In normal operation, the sensor output does not change when there is only background, and the concentration is constant (for example, transmittance 90/7)? , ) The reference voltage 7 of the comparator 6 is set so that the sensor outputs when smoke exists.

In order to confirm whether or not this sensor is operating normally, an instruction from the outside, for example, by increasing the control voltage from the control circuit 1 to the power supply circuit 2 using a changeover switch, is applied to the light emitter 3. increase the current flowing to The amount of light emitted from the light emitter 3 increases in proportion to the current index, and the amount of scattered light proportional to the amount of light emitted is obtained. The bank ground also increases in proportion to the amount of light emitted. The reference voltage 7 is switched at the same time as the luminescence amount is changed, and the comparator 6 is switched while the bank ground is increased.
Set it so that it is on. By doing this, it is possible to check the sensor operation even when there is no smoke.

In this confirmation operation, if the control circuit 1 is positive, a preset voltage is applied to the light emitter power supply circuit 2, and if the light emitter power supply circuit 2 is positive, a current corresponding to the voltage applied from the control circuit 1 is applied to the light emitter power supply circuit 2. flows to the light emitter 3.゛The light emitter 3 emits light with an amount proportional to the index of the flowing current, the photoreceptor 4 outputs an output corresponding to the amount of received light, the amplifier 5 amplifies it at a constant amplification factor, and the comparator 6
compares the amplifier 5 with a reference voltage 7, and the output circuit 8 provides a sensor output 9 in response to the output of the comparator 6. In this way, if all the circuits are normal, a sensor output confirming operation is obtained by the confirmation operation.

In this case, the operation is checked on the condition that there is no smoke inside the smoke detector. Therefore, unless it is confirmed that there is no smoke, even if the operation is confirmed,
This does not mean that accurate operation has been confirmed. That is, the operation has been confirmed based on the absolute value of the background incident on the scattered light photoreceptor 4. However, in the presence of smoke, there is an amount of light scattered by the smoke, which increases with increasing smoke concentration.

This introduces uncertainty into operation confirmation that focuses only on background changes.

The present invention is based on the above-mentioned conventional technology and provides a light emitter and a photoreceptor by changing the amount of light emitted from the light emitter.

The purpose is to improve the circuits that check the operation of the amplifier that amplifies the photoreceptor output, the comparator that compares the amplifier output with a constant value, and the sensor output circuit that outputs the sensor output based on the blower output. .

Embodiments of the present invention will be described below with reference to the drawings.

In this embodiment, the operation is confirmed regardless of the presence or absence of smoke by increasing or decreasing the amount of light emission and comparing before and after the change. FIG. 2 is a diagram showing its configuration. The power supply circuit 12 supplies current to the light emitter 13 according to instructions from the control circuit 11, and the light amount control circuit 11 maintains constant light emission.

Note that the current supply circuit to the light emitter has a function of changing the supplied current. There are two means for changing the supplied current. One is a means to change by instructions from outside,
The other method is to do it internally and automatically.

At a certain amount of light emission, the scattered light receiver 14 receives the amount of light that is the sum of the background and the scattered light due to smoke if there is smoke, and the output amplified by the amplifier 15 is held in the memory 22 for sample holding. The output of the memory 22 is compared with a reference voltage 17 by a comparator 1.6 and input to a sensor output circuit 18. Output 19 from sensor output circuit 18
can be used to measure smoke concentration.

Next, the control circuit 1
1 to tm", and a current is passed through the light emitter through the light amount control circuit 12. At this time, if there is smoke, the amount of scattered light due to the background and smoke will both be doubled, so the sum of the amount of scattered light to the photoreceptor 14 is The total amount of incident light is also doubled.If the difference or ratio with the previously sampled and held value is taken by the computing unit 23, the output of the computing unit 23 will be 1/1 of the sampled and held value.
It will be doubled. When k times 1, it is doubled to 1-. If we take the ratio of the two values, we get k or 1/k. In any case, this is the value that can be predicted using the window type comparator 24.
It is determined whether or not the voltage is within the voltage range defined by the reference voltage 25, and the result is input to the operation confirmation output circuit 26 to confirm the operation.

When this operation check is performed based on an external instruction, an operation check switch is provided on the sensor, and the result is displayed on a light emitting diode or the like using the output of the operation check output circuit 26, so that it can be done easily even when the sensor is removed. operation can be easily confirmed. By providing operation confirmation lines for each location, it is also possible to centrally manage a large number of sensors.

It is also possible to apply this operation check to a pulse operation sensor, and furthermore, the reliability of the sensor can be improved by automatically checking the operation for each pulse operation. Furthermore, even if the light emitter or the photoreceptor has deteriorated, it can be easily confirmed whether the sensor circuit is operating normally. Note that the present invention can be applied not only to the case where the output of the sensor is a binary value of on and off, but also to the case where it is an analog output.

As described above, in the smoke detector of the present invention, accurate operation can be confirmed regardless of whether smoke is present in the smoke detector.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a smoke detector according to an embodiment of the prior art, and FIG. 2 is a block diagram of a smoke detector according to an embodiment of the present invention. 1.11...Control circuit, 2,12...Power source, 3゜13...Light emitter, 4.14...Scattered light receiver, 5゜15. ...Scattered light photoreceptor output amplifier, 6, 16...Comparator, 7, 17...
...Reference voltage, 8,18...Sensor output circuit,
9, 19...Sensor output, 2゜...Direct light receiver, 21...Direct light reception off output amplifier, 22...Sample hold Circuit, 23...
... Arithmetic unit, 24 ... Wind type comparator,
25... Reference voltage, 26... Operation confirmation output circuit.

Claims (3)

[Claims] (1) A light emitter, a scattering optical light body that does not directly receive emitted light from the light emitter, a control circuit that changes the amount of light emitted by the light emitter by a predetermined value, and a memory that stores the output of the light emitter. a calculation unit that calculates the output of the scattering optical light body and the output of the memory when the amount of light emission of the light emission body is changed; a circuit that ratios the output of the calculation unit and a reference value; The smoke device comprises a circuit for comparing the output of the body with a predetermined value, the output of the circuit for comparing with the reference value is used as an operation confirmation output, and the output of the circuit for comparing with the predetermined value is used as a smoke detection output. sensor. (2) The smoke detector according to claim 1, wherein the arithmetic circuit has a subtraction or division function. (3) The smoke detector according to claim 1, wherein the light emission control circuit feeds back the output of a photoreceptor that directly receives the emitted light from the light emitter to the light emitter drive source.