JPS6316999Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a smoke detection device that uses an optical fiber as a signal transmission path.In particular, the light emitting element serving as the light source is driven to emit light by connecting a power supply line, and the light is obtained through a smoke detector. The present invention relates to a photoelectric separation type smoke sensing device that sends out scattered light or transmitted light through an optical fiber.

Conventionally, in this type of smoke detection device, a smoke detector installed in a restricted area and a receiver or repeater are electrically connected by a signal line, and light scattered or transmitted by smoke is converted into an electrical signal by a light receiving element. It is then converted to , and sent to the receiver side.

However, if connections using signal lines are installed in locations that are susceptible to inductive noise, such as power plants, substations, or facilities that use large amounts of electricity, inductive noise may enter the signal line and cause non-fire alarms. I was afraid.

Therefore, in order to prevent non-fire alarms due to induced noise, for example, a receiver 1 is installed in a place where the influence of induced noise is small, and a smoke detector 2 is installed in a caution area.
are connected by a light source optical fiber 3 and a light receiving optical fiber 4, and the light from the light emitting element 5 provided in the receiver 1 is sent to the smoke detector 2 via the optical fiber 3 and sent to the smoke detector 2a. The scattered light from the smoke that has entered the smoke detection section 2a is sent back to the receiver 1 via the optical fiber 4, and photoelectrically converted by the light receiving element 6 of the receiver 1, thereby eliminating the influence of electrical noise such as induced noise. Devices that can be made to disappear are being considered.

However, although the above device has the advantage of being completely unaffected by electrical noise, since the light source is also sent to the smoke detector 2 through the optical fiber 3, the light emitting element 5 and the optical fiber 3 are connected to each other. The amount of light at the smoke detector 2 is greatly attenuated due to the coupling loss between the fibers and the transmission loss proportional to the length of the optical fiber 3, and a considerable amount of light is wasted, and the decrease in the amount of light causes a deterioration of the S/N ratio. This led to the problem that the transmission distance by optical fiber was restricted.

The present invention was developed by focusing on these conventional problems, and aims to provide smoke detectors with a sufficient amount of light from a light source without being affected by induced noise. The smoke detection unit to be installed is equipped with a light emitting element and a light receiving lens that receives scattered light or transmitted light from the light emitting element due to smoke, and the light emission from the electric circuit section of the receiver or repeater placed separately from the smoke detection unit is provided. By connecting the drive circuit to the light-emitting element of the smoke detector through a power supply line to drive the light emission, and by connecting the light-receiving lens of the smoke detector to the light-receiving element of the receiver side through an optical fiber for photoelectric conversion. , aims to solve the above problems.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 2 is an explanatory diagram showing an embodiment of the present invention.

First, to explain the configuration, numeral 10 is an electric circuit section installed in a repeater etc. installed in a place that is not easily affected by induced noise, numeral 12 is a smoke detection section installed in a predetermined caution area. 12 is provided with a light emitting element 14 serving as a light source and a light receiving lens 16 receiving scattered light of smoke flowing into the smoke detection section 12a.

On the other hand, the electric circuit section 10 is provided with a light emission drive circuit 18 for driving the light emitting element 14 of the smoke detection section 12, and a power supply line is connected between the light emission drive circuit 18 and the light emitting element 14 of the smoke detection section 12. They are connected by l and l'. Further, the electric circuit section 10 is provided with a light receiving element 20, which is connected to the light receiving lens 16 of the smoke detection section 12 through an optical fiber 22.
Scattered light from the smoke detecting section 12a received at 6 is incident on the light receiving element 20 via the optical fiber 22. The light reception signal by photoelectric conversion of the light receiving element 20 is
It is input to the amplifier 24 and amplified to a predetermined level,
Further, the amplified signal of the amplifier 24 is input to an alarm circuit 26, and when the level of the received light signal exceeds a reference level, the alarm circuit is configured to send an alarm signal to a receiver (not shown) via signal lines L and L'. ing.

Next, the action will be explained.

The light emitting element 14 of the smoke detection unit 12 is connected to the power supply line l,
It is driven to emit light by a drive signal outputted from the light emission drive circuit 18 of the electric circuit section 10 via l', and irradiates light onto the smoke detection section 12a.

When smoke from a fire flows into the smoke detection section 12a of the smoke detection section 12 in this state, the light from the light emitting element 14 is diffusely reflected by the smoke particles, and scattered light enters the light receiving lens 16. The light is focused by the lens 16 and enters the optical fiber 22, and is transmitted to the light receiving element 20 of the electric circuit section 10 via the optical fiber 22.
is incident on the Therefore, the light-receiving element 20 inputs a light-receiving signal proportional to the scattered light obtained by the light-receiving lens 16 to the amplifier circuit 24, and when the amplified signal of the amplifier circuit 24 to the alarm circuit 26 exceeds a predetermined reference level, The alarm circuit 26 outputs an alarm signal to the receiver via signal lines L and L', and the receiver issues a fire alarm.

On the other hand, as for the influence of induced noise, although induced noise mixes into the power supply lines l and l' connected to drive the light emitting element 14 to emit light, the light emitting element 14
When a light emitting diode is used as the light emitting diode, the light emission driving current is several tens to hundreds of mA, so even if induced noise is mixed in, the intensity of light from the light emitting element 14 will hardly change due to the induced noise. , there is almost no influence of induced noise on the driving of the light emitting element 14. Further, regarding the transmission of the scattered light received by the light receiving lens 16, since it is sent to the light receiving element 20 by the optical fiber 22, it is not affected by electrical noise such as induced noise at all, and the smoke detection unit 1
2 is installed in a place where the influence of induced noise is large, the generation of non-fire alarms due to induced noise can be reliably prevented.

Of course, since the light source of the smoke detection section 12 electrically drives the light emitting element 14 via the power supply lines l and l', it is necessary to obtain a sufficient amount of light necessary for smoke detection in the smoke detection section 12a. There is no problem of loss due to attenuation of light from the light source.

Although the above embodiment takes a scattered light type smoke detector as an example, the same applies to a transmitted light type smoke detector in which the light from the light emitting element is attenuated by the inflow of smoke. It is. Further, in the above embodiment, the electric circuit section 10 is provided in the repeater, but
An electric circuit section 10 is provided in the receiver, and power supply lines l, l' and an optical fiber 2 are connected between the receiver and the smoke detection section 12.
2 may be used for connection. Furthermore, in the above embodiment, a spot-type smoke detector was taken as an example in which a light emitting element and a light receiving lens were incorporated into a single detection part, but the light emitting part and the light receiving part were separated by a predetermined distance. The present invention can also be applied to so-called separate smoke detectors arranged separately.

As explained above, according to the present invention, the structure is a smoke detector installed in a restricted area, which has a light emitting element and a light receiving lens that receives light scattered or transmitted by smoke from the light emitting element. , a light emitting drive circuit that controls lighting of the light emitting element which is arranged separately and connected to the light emitting element of the smoke detection part via a power supply line, and an optical fiber connected to the light receiving lens of the smoke detector. and an electric circuit section that includes a light receiving element that photoelectrically converts the light received by the light receiving lens and an alarm circuit that outputs an alarm signal based on the light receiving output of the light receiving element. Smoke detection unit 1 is used to obtain scattered light due to inflow of smoke or transmitted light that is attenuated due to inflow of smoke.
The intensity of the light source in step 2 can be obtained as a sufficient amount of light without causing light attenuation, and on the other hand, the smoke detection light obtained from the smoke detection section is converted into a light source by the electric circuit section via an optical fiber. Therefore, even if the smoke detector is installed in a place that is susceptible to induced noise, the effect of induced noise will not appear on the received light signal, and the generation of non-fire alarms due to induced noise can be reliably prevented. Since the strength of the light is sufficient, the length of the optical fiber that transmits the smoke detection light can be made sufficiently long, and the effect of smoke detection that effectively utilizes the advantages of the optical fiber can be obtained. .

In the embodiment shown in Fig. 2, the optical fiber 22 and the power supply lines l and l' are provided separately, but if a so-called composite cable in which the optical fiber and the electric wire are combined into the same cable is used, the optical Fibers and feeders can be laid in a single cable.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a conventional device using an optical fiber, and FIG. 2 is an explanatory diagram showing an embodiment of the present invention. 10... Electric circuit section, 12... Smoke detection section, 12
a...Smoke detector, 14...Light emitting element, 16...Light receiving lens, 18...Light emission drive circuit, 20...Light receiving element, 22...Optical fiber, 24...Amplifier, 2
6... Alarm circuit, l, l'... Power line, L, L'...
Signal line.

Claims (1)

[Scope of Claim for Utility Model Registration] A smoke detection unit installed in a restricted area that has a light emitting element and a light receiving lens that receives scattered light or transmitted light from the smoke from the light emitting element; A light-emitting drive circuit that is connected to the light-emitting element via a power supply line and controls lighting of the light-emitting element, and a light-receiving element that is connected to the light-receiving lens of the smoke detection unit via an optical fiber and photoelectrically converts the light received by the light-receiving lens. , and an electric circuit section including an alarm circuit that outputs an alarm signal based on the light reception output of the light receiving element, are arranged separately from the smoke detection section. Device.