JPS6138548A - Setting method of initial level of scattered light type smoke detector - Google Patents

Abstract

PURPOSE:To detect the breaking of a light source, a decrease in the quantity of light, etc., by adjusting the brightness of dark box constituent materials of the smoke detector and internal surface paint for the dark box to optional values. CONSTITUTION:When the brightness of the dark box is adjusted, materials and paints which vary in brightness from low (black) gradually are prepared and a material or paint corresponding to a spacific noise light signal is determined, and a material or paint having brightness corresponding to it is only used. When only the wire breaking of a light emitting element is detected, a decision is made with a small quantity of the noise light signal, so a material or paint with low brightness is selected. When a decrease in the quantity of light of the light emitting element is detected, on the other hand, the level of an initial noise light signal needs to be set high, so a material or paint having relatively high brightness needs to be selected. Thus, the amount of the initial noise light signal is adjusted by selecting the material and paint for the dark box, thereby obtaining various fault signals. Further, the level variation of a fire signal accompanying variation in initial level is adjusted by varying the amplification factor of an amplifier.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for setting an initial level of a scattered light type smoke detector that detects light scattered by fine particles of smoke generated when a fire occurs.

[Conventional technology]

In scattered light smoke detectors that detect fire by detecting light scattered by smoke particles, the diffusely reflected light (noise light) signal generated in the dark box is constantly monitored, and by detecting the extinction of this signal, the light emitting element etc. For detecting the failure of
There is Publication No. 1.

As shown in FIG. 1, the configuration of such a conventional scattered light type smoke detector includes a pulse generation circuit 1, a dark box 5, and a light emitting element 3 that is pulse-lit by the output pulse of the pulse generation circuit 1. , a light receiving element 4 that detects light scattered by smoke in the dark box 5, an amplifier 6, a fire signal detection circuit 7 that generates an output signal when an output of the amplifier 6 of a predetermined level or higher is applied, and a fire signal detection circuit 7 of the amplifier 6. a fault signal detection circuit 8 that generates an output signal when the output becomes below a predetermined level, and an AND game that takes the logical product of the outputs of these detection circuits 7 and 8 and the output signal of the pulse generation circuit 1), 9.10 They each have the following. .

The dark box 5 of such a smoke detector has a labyrinth structure to prevent outside light from entering in order to increase the S/A ratio, and is generally made of a black material or one whose surface is coated with black paint.

The relationship between the smoke density in the dark box 5 and the output voltage of the light receiving element 4 is shown by the solid line X in the graph of FIG. The vertical axis of this graph shows the output voltage (mv) of the light receiving element 4, and the horizontal axis shows the smoke density (light attenuation rate %/m2), and the range shown by the parallel lines X, , X, above and below the solid line X is , represents the error range that occurs in common manufacturing structures or circuits. For example, if a fire signal is to be issued at a smoke density of 10%/m, a circuit is used that issues a fire signal when the output voltage of the light receiving element 4 reaches approximately 3 mV.

In this graph, the noise optical signal is 0.6mV±0.2mV
The presence or absence of this voltage is detected and the fault signal detection circuit 8 generates a fault signal.

[Problem that the invention seeks to solve]

In the conventional smoke detectors as described above, the noise optical signal is extremely small, and therefore the manufacturing error range is, for example, X3. In some cases, no noise optical signal can be obtained at all in the case of the type represented by X.

In addition, it was difficult to detect noise optical signals in several stages and to detect a disconnection of the light source as well as a decrease in the amount of light.

[Failure to solve the problem]

This invention solves the above problems by adjusting the brightness of the material constituting the dark box or the paint on the inner surface of the dark box to an arbitrary value.

[For production]

To adjust the brightness of the dark box, use one with low brightness (black).
If you want to obtain a noise optical signal with a large amount, you can prepare gradually higher amounts of noise optical signals in advance, determine the brightness of a predetermined noise optical signal, and then use a material or paint with the color of the determined brightness. , one with relatively high brightness may be selected, and one with low brightness may be selected if the amount of noise optical signal is small.

For example, when detecting only a disconnection in the light emitting element 3, it can be determined with a relatively small amount of noise optical signal, but when detecting also the rate of change in the era name of the light emitting element 3, the amount of noise optical signal,
That is, it is necessary to set the initial noise optical signal level high.

〔Example〕

Figure 3 shows a graph showing the relationship between brightness and noise light signal using a dark box of our photoelectric smoke detector (Model 2KC).

The vertical axis shows the output voltage (mV) of a light receiving element (NJL612B manufactured by New Japan Radio ■), and a light emitting element (NJLII i oB manufactured by New Japan Radio ■) was used. The horizontal axis represents brightness. The dark box in this embodiment is made of synthetic resin, and although achromatic colors (black→white) are used, chromatic colors may also be used. The relationship between the smoke density and the light-receiving element output voltage as the brightness changes is expressed by moving X in Figure 2 almost parallel up and down (e.g. Although it changes somewhat depending on the type of element, etc., even if these changes are taken into account, the initial noise optical signal amount can be adjusted within the brightness range of 2 to 5. The change in the fire signal level due to the change in the initial level may be adjusted by changing the amplification factor of the amplifier.

〔Effect of the invention〕

A synthetic resin material or paint with a predetermined brightness can be selected and managed relatively easily, and if the initial noise light signal level of a scattered light smoke detector is set by adjusting the brightness of the dark box as in this invention, the noise will be reduced. Since the amount of optical signals can be increased, the error range of the product can be widened, and since a detailed noise optical signal can be obtained without using a complicated circuit, various failure signals can be obtained. It will be very effective if used in a system in which the receiver receives quantized analog information from a redundant smoke detector.

[Brief explanation of the drawing]

Figure 1 shows the initial stage of the scattered light type smoke detector of this invention. Brightness Japanese Patent Application tI-38548 Manual continuation supplementary book January 2C, 1985

Claims (1)

[Claims] 1) A dark box having a labyrinth structure, a light emitting element that projects light into the dark box, and a light receiving element that receives light scattered by smoke from the light emitting element, and there is no smoke. In a scattered light type smoke detector that detects a failure by using the diffusely reflected light (noise light) signal of the dark box in the state, the brightness of the dark box surface is adjusted by at least 2 to 5 box circumferences. An initial level setting method for a scattered light smoke detector, characterized in that a diffusely reflected light (noise light) signal is obtained. 2) The initial level setting method for a scattered light type smoke detector according to claim 1, wherein the dark box is made of a synthetic resin molded body, and the brightness of the synthetic resin material is adjusted.