JPS6041794B2 - Smoke detectors - Google Patents

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 sensor that can be used to check whether the sensor is operating normally. Photoelectric scattering light type smoke detectors are installed inside a structure that allows smoke to easily enter and blocks outside light.
The light emitter and the light emitted from the light emitter are not received directly,
The light emitting device is composed of a scattered light receiver that receives the light that is scattered by the light emitter due to the presence of smoke, and further includes an electronic circuit that controls these light emitting receivers.

Conventional photoelectric scattering type smoke detectors cannot confirm whether or not the light emitter, the phosphor itself, and the control circuit are operating normally.

The present invention achieves the following by changing the amount of light emitted from the light emitter.
A circuit is provided to check the operation of an amplifier that amplifies the output of the emitter, photoreceptor, and phosphor, a comparator that compares the amplifier output with a constant value, and a sensor output circuit that outputs the sensor output based on the comparator output. There is a particular thing.

In a photoelectric scattering light type smoke detector, there is no sensor output when there is no smoke, but for example, if the luminous body has deteriorated and does not emit light, the sensor will not output regardless of the presence or absence of smoke.

The present invention provides a circuit in which a sensor is provided with an operation check function in order to avoid a situation where the sensor output is not output when smoke is present due to a decline in the function of a part of the sensor. The photoelectric scattering light type smoke detector according to the present invention basically has the following configuration.

A light emitter, a scattered light receiver, and a direct light receiver are placed in predetermined positions within a structure that allows smoke to easily flow in and blocks external light. It consists of an amplifier that amplifies the output of the photoreceptor, a comparator that compares the output of the amplifier with a reference voltage, and a circuit that controls the output of the sensor based on the output of the comparator.

FIG. 1 shows one conventional example, in which a 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 surrounding walls, etc., and enters the light receiver as a background. When operating as a photoelectrically scattered light type smoke detector, the amount of light incident on the photoreceptor is the sum of the background light and the light scattered by smoke. In normal operation, the reference voltage 7 of the comparator 6 is set so that the sensor output is not generated when only the background is present, but when smoke of a certain concentration (for example, transmittance 90%/RrL,) is present. are doing. 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, the voltage flows to the light emitter 3. Increase current.

The amount of light emitted from the light emitter 3 increases in proportion to the current index,
The amount of scattered light is proportional to the amount of light emitted. The background also increases in proportion to the amount of light emitted. The reference voltage 7 is switched at the same time as the amount of light emission is changed, and is set so that the comparator 6 is turned on when the background increases. 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 normal, a preset voltage is applied to the light emitter power supply circuit 2, and the light emitter power supply circuit 2 supplies a current to the light emitter according to the voltage applied from the control circuit 1. flow to
The light emitter 3 emits light with an amount proportional to the index of the flowing current, the light emitter 4 outputs an output corresponding to the amount of light emitted, the amplifier 5 amplifies with a constant amplification factor, and the comparator 6 connects the amplifier 5 and the reference voltage. 7
The output circuit 8 outputs a sensor output 9 according 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. [Embodiment 1] Although the confirmation operation is performed in accordance with the conventional example, normal operation may not be achieved if there is slight deterioration of each circuit or component.

In photoelectric scattering light type smoke detectors, deterioration of the light emitter, especially a decrease in luminous efficiency over time, and a decrease in the apparent amount of light emitted and the amount of light received due to contaminants that adhere and accumulate on the surface of the light emitter and photoreceptor. is the biggest cause of functional decline. FIG. 2 shows an embodiment of the present invention. In order to avoid the above-mentioned deterioration, a direct light receiver 20 that directly receives the light from the light emitter 13 is provided in addition to the scattered light receiver 14. The output of the light emitter 20 is amplified by the amplifier 21, and this output is fed back to the control circuit 11, and the output is directly transmitted to the light emitter 13 and the light receiver 20, regardless of deterioration of the light emitter 13 and the light receiver 20 and the adhesion and accumulation of contaminants.
A light amount control circuit 11 is provided to keep the amount of light received at 0 constant. In this way, the control circuit 11 is instructed to perform a confirmation operation from the outside, increasing the current flowing to the light emitter 13, and controlling the amount of light received as expected regardless of the deterioration or contamination of the light emitter 13 and the photoreceptors 20, 14. do. Contaminants are deposited on the surfaces of the photoreceptors 14 and 20 because both the direct photoreceptor 20 and the scattered light photoreceptor 14 are in the same atmosphere, have the same shape, and are placed on the same plane.
The amount of accumulation will be about the same.

From this, the scattered light photoreceptor 14 receives a constant amount of light determined by the light amount control circuit 11, and both the scattered light from the smoke and the background become constant. Therefore, by increasing the amount of light received, the background also increases, and by switching and setting the reference voltage 17 at the same time as changing the amount of light emitted so as to correspond to this increased value,
Outputs operation confirmation output 19. In addition, 12, 15, 16, 1
8 corresponds to 2, 5, 6, and 8 in FIG. As described above, according to the present invention, it is possible to easily check whether the sensor circuit is operating normally even if the light emitting body or the light receiving body has deteriorated.

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 the output is an analog output.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a conventional smoke detector, 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 supply, 3, 13... Light emitter, 4, 14...
・Scattered light photoreceptor, 5, 15...Amplifier of scattered photoreceptor output, 6,16...Comparator, 7,17...
...Reference voltage, 8,18...Sensor output circuit, 9,19...Sensor output, 20...Direct photoreceptor, 21...Direct Amplifier of photoreceptor output.

Claims (1)

[Claims] 1. A light emitter, a scattered light receiver that does not directly receive the light emitted from the light emitter, a direct light receiver that directly receives the light emitted from the light emitter, and a light receiver that changes the amount of light emitted by the light emitter and receives the direct light. A control circuit to which the output from the body is fed back, and a comparator that compares a value based on the output of the scattered light receiver when the amount of light emitted from the light emitter changes with a predetermined value. Smoke detector.