JP2565209Y2 - Radiant fire detector - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a radiant fire detector, and more particularly, to a radiant fire detector using, for example, a pyroelectric infrared detector as a detector for detecting infrared rays emitted from a flame. Things.

[0002]

2. Description of the Related Art A radiant fire detector uses, for example, a pyroelectric infrared detecting element (hereinafter referred to as a pyroelectric element) as a detecting element, and detects infrared rays emitted from a fire flame to detect the occurrence of a fire. Is what you do.

FIG. 5 is a sectional view showing an example of a conventional radiation type fire detector. In the figure, reference numeral 1 denotes a housing, which is substantially a cylindrical main body 2 having a bottom plate 3 and a cover 4 connected to the main body 2 by a locking claw. Thus, a light transmitting window 5 is provided on the upper surface.

[0006] Reference numeral 6 denotes a printed circuit board on which electric components constituting an amplification circuit, a fire discrimination circuit, a switching circuit, and the like (not shown) are mounted. The printed circuit board is housed in the main body 2 and fixed to the bottom plate 3 by screws 7. . Reference numeral 8 denotes a pyroelectric element in which a pyroelectric body is accommodated in a case having a light receiving window and detects infrared rays radiated from a flame.
Mounted on the printed circuit board 6, and its lead wires are soldered to the printed circuit board 6. At this time, the light receiving window of the pyroelectric element 8 is disposed at a position facing and close to the light transmitting window 5 of the cover 4.

In the above-described radiant fire detector, when a fire occurs, the pyroelectric element 8 detects infrared rays emitted from the flame, amplifies the output signal, and compares the amplified output signal with a reference value in a fire discriminating circuit. When the detected value exceeds the reference value, a fire signal is output and transmitted to a fire receiver or the like, and an alarm is issued.

[0006]

When the above-described radiant fire detector is installed outdoors or the like, external light such as sunlight passing through the translucent window 5 irradiates the case of the pyroelectric element 8. Heat. For this reason, the pyroelectric body in the case may detect this heat, output a detection signal from the pyroelectric element 8, and issue a fire alarm even though no fire has occurred.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a radiant fire detector which does not cause a malfunction even when sunlight or the like irradiates a pyroelectric element. It is.

[0008]

According to the present invention, there is provided a radiant fire detector according to the present invention, comprising a housing having a bottomed cylindrical main body, a light-transmitting window provided on an upper surface, and a cover coupled to the main body; A circuit, a printed circuit board provided with a fire determination circuit and the like and housed in the housing, and a pyroelectric element disposed between the printed circuit board and the light-transmitting window of the housing and connected to the printed circuit board, A light-shielding body having an inner diameter substantially equal to the outer diameter of the pyroelectric element; and a light-shielding body into which the pyroelectric element is fitted. And the outer diameter of the light-shielding body is formed larger than the inner diameter of the light-transmitting window.

[0009]

When the sunlight or the like irradiates the pyroelectric element, the case other than the light receiving surface of the pyroelectric element is shielded from light by the light shielding body, so that the case of the pyroelectric element is not directly heated.

[0010]

1 is a sectional view of an embodiment of the present invention, and FIG. 2 is a plan view thereof. In both figures, reference numeral 10 denotes a housing, which comprises a cylindrical main body 11 having a bottom plate 12 and a cover 13 connected to the main body 11 by locking claws.
1 and a cylindrical portion having a smaller diameter than the connecting portion formed above the inclined portion and an inclined portion reduced in diameter upward from the connecting portion. A light transmitting window 14 is provided. Reference numeral 15 denotes a plurality of engaging portions projecting around the light transmitting window 14 and opening downward.

Reference numeral 16 denotes a window plate made of sapphire as an infrared filter disposed on the light- transmitting window 14 via a packing 17.
The engaging portion 15 is filled with a filler 19 such as silicone rubber for waterproofing. Reference numeral 20 denotes an LED display window provided on the inclined portion of the cover 13, and reference numeral 21 denotes a plurality of fins formed at substantially equal intervals from the side wall of the cylindrical portion of the cover 13 to the inclined portion.

Reference numeral 30 denotes an electric circuit section housed in the housing 10, and the electric circuit section 30 has a pyroelectric element 32 mounted thereon.
First printed circuit board 31 provided with a preamplifier section and the like
And a second printed board 34 provided with a main amplifier section, a fire discriminating section, and the like. The first printed board 31 and the second printed board 34 are Coupled and electrically connected to the stage. In this embodiment, the pyroelectric element 3
2 is mounted on the first printed circuit board 31, and the lead wires inserted into the through holes are soldered on the lower surface of the first printed circuit board 31. Reference numeral 33 denotes a shield case that covers a preamplifier and the like provided on the first printed circuit board 31.

Reference numeral 36 denotes a metal blade provided on the lower surface of the main body 11, fixedly connected to a terminal of a base provided on a ceiling or the like, and electrically connected thereto. While being fixed to the main body 11 by the screw 37,
It is connected to the blade fitting 36.

Reference numeral 40 denotes an elastic body having a heat-preventing property such as urethane foam, for example.
A cylindrical shielding body having an outer diameter D as shown in FIG. 3 is greater than the inner diameter D ₁ of the transparent window 14 provided on the casing 13, the inner diameter d of the fitting hole 41 pyroelectric element 32 out of the It is formed equal to or slightly smaller than the diameter d ₁ and has a height h
Is substantially equal to the height h ₁ from the upper surface of the light-transmitting window 14 to the first printed circuit board 31, and therefore, the upper surface of the light shielding body 40 is formed at a height substantially equal to the light receiving surface of the pyroelectric element 32.

In order to mount such a light shield 40, the first printed circuit board 31 is connected to the second printed circuit board 31 by connecting pins 35.
The printed circuit board 34 is fixed to the main body 11 with screws 37, and the pyroelectric element 32 mounted on the first printed circuit board 31 is fixed.
The outer peripheral wall of the pyroelectric element 32 is covered by fitting the fitting hole 41 of the light-shielding body 40 to the outer peripheral surface. Next, when the cover 13 is connected to the main body 11, the light shielding body 40 is held between the cover 13 and the first printed circuit board 31, the light receiving window of the pyroelectric element 32 is opened by the fitting hole 41, and It is arranged to face the window 14.

In the present invention configured as described above,
Even if sunlight or the like irradiates the pyroelectric element 32, the light-shielding body 40 blocks light other than the light receiving surface of the pyroelectric element 32, and the case is not directly heated by external light such as sunlight. Therefore, malfunction of the detector due to heating of the case of the pyroelectric element 32 can be prevented.

FIG. 4 is a partial sectional view of another embodiment of the present invention. In this embodiment, the cover 1 is provided on the transparent window 14 of the cover 13.
3 is provided with a light-shielding body 45 consisting of a flange 46 continuous with the cylindrical body 47 and a cylindrical part 47 having a size substantially corresponding to the case of the pyroelectric element 32 at the center thereof. The cylindrical portion 47 of 45 is fitted to the outer peripheral wall of the pyroelectric element 32 to shield light.

Also in this embodiment, since the case of the pyroelectric element 32 is not directly heated by the sunlight or the like by the light shielding body 45, malfunction due to heating of the case can be prevented.

[0019] In the above description, the case of providing the light-shielding body according to the present invention the radiant fire detector as shown in FIGS. 1 to 3, for example radiant fire structure as shown in FIG. 5 The present invention can be applied to a sensor.

[0020]

As described in detail above, in the present invention, a light shield surrounding the side surface of the pyroelectric element is provided around the pyroelectric element. It is not directly heated by light or the like. Therefore, malfunction of the sensor due to heating of the case can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

FIG. 2 is a plan view of FIG. 1;

FIG. 3 is a perspective view of an embodiment of a light shield.

FIG. 4 is a partial cross-sectional view of another embodiment of the present invention.

FIG. 5 is a cross-sectional view of an example of a conventional radiation fire detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Case 11 Main body 13 Cover 14 Translucent window 31 First printed circuit board 32 Pyroelectric element 34 Second printed circuit board 40, 45 Light shield

Claims (3)

(57) [Scope of request for utility model registration] 1. A housing comprising: a bottomed cylindrical main body; and a cover provided with a light transmitting window on an upper surface and coupled to the main body;
A printed circuit board provided with an amplifier circuit, a fire discrimination circuit and the like and housed in the housing, and a pyroelectric element disposed between the printed board and the light transmitting window of the housing and connected to the printed circuit board. A fitting hole having an inner diameter substantially equal to the outer diameter of the pyroelectric element.
And a light-shielding body into which the pyroelectric element is fitted in the fitting hole.
And the upper surface of the light shield is substantially equal to the light receiving surface of the pyroelectric element.
And the outer diameter of the light-shielding body is
A radiant fire detector characterized by being formed larger than the inner diameter of the window . 2. The radiant fire detector according to claim 1, wherein the light shielding body is formed of a donut-shaped elastic material having a hole at a center portion into which a pyroelectric element is fitted. 3. A flange portion provided in a light-transmitting window in a manner continuous with a cover, and a cylindrical portion extending downward at a center portion thereof in a size substantially corresponding to a case of a pyroelectric element. 2. The radiant fire detector according to claim 1, wherein: