JPH05303699A - Radiation type fire sensor - Google Patents

Abstract

PURPOSE:To provide a radiation type fire sensor which can prevent the shift of a photodetecting element and the bending of a lead wire that are caused by the impacts and the vibrations and is never affected by the electromagnetic waves. CONSTITUTION:A casing 10 contains a bottomed cylindrical main body 11 and a cover 13 which includes a sloping part connected to the body 11 and having its diameter reduced toward the upper part and a light transmitting window 14 formed on the upper bottom. Then a 1st printed board 31 is stored in the sloping part of the casing 10 together with a 2nd printed board 35 which is connected to the lower part of the board 31 and stored in the casing 10, and a photodetecting element 33 which is provided between the window 14 of the casing 10 and the board 31 and connected to this board 31. Furthermore a preamplifying part is added to the board 31 to amplify at least the output of the element 33.

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 which is installed in, for example, a tunnel or a cave and detects the flame of a fire to detect the occurrence of the fire.

[0002]

2. Description of the Related Art A radiant fire detector uses, for example, a pyroelectric infrared detection element (hereinafter referred to as a pyroelectric element) as a detector, and detects infrared rays emitted from a fire flame to detect the occurrence of a fire. It is a thing.

FIG. 7 is a sectional view showing an example of a conventional radiant fire detector. In the figure, reference numeral 60 denotes a housing, and a bottom plate 62.
And a cover 63 connected to the main body 61 by locking claws 64. The cover 63 is formed in a substantially Mt. A translucent window 65 is provided in the.

Reference numeral 66 is a printed circuit board on which electric parts constituting an amplifier circuit, a fire discrimination circuit, a switching circuit and the like (not shown) are mounted, which is housed in the main body 61 and fixed to the bottom plate 62 by screws 67. .. Reference numeral 68 is a light receiving element such as a pyroelectric element that receives and detects the light of flame, and is a cylindrical mount 7
It is mounted on the printed circuit board 66 through 0, and its lead wire 69 is soldered to the printed circuit board 66. At this time, the light receiving element 68 has the transparent window 65 of the cover 63.
Is arranged at a position facing and close to.

In the conventional radiant fire detector as described above, it is difficult to miniaturize the printed circuit board 66, because the printed circuit board 66 is mounted with a large number of electric parts constituting an amplifier circuit and the like. For this reason, even if the light receiving element 68 is made to approach the light transmitting window 65, the printed circuit board 66 is attached to the housing 6.
Since it cannot be housed above 0, that is, in the inclined portion of the cover 63, it is arranged in the cylindrical main body 61. Therefore, in order to bring the light receiving element 68 close to the transmission window 65,
The light receiving element 68 is connected to the printed circuit board via a long lead wire 69, or the mount 70 supports the light receiving element 68, and the lead wire 69 is connected to the printed circuit board 66 so that the light receiving element 68 faces and is close to the light transmitting window 65. ing.

[0006]

The conventional radiant fire detector as described above has the following problems.

(1) Since the lead wire 69 of the light receiving element 68 becomes long, it acts as an antenna, and electromagnetic waves are easily picked up to cause malfunction.

(2) When the light receiving element 68 is supported only by the lead wire 69, the lead wire 69 is bent due to impact or the like and the position of the light receiving element 68 is displaced, resulting in a deviation in the monitoring range and sensitivity.

(3) When a pyroelectric element for detecting infrared rays is used as the light receiving element 68, the pyroelectric element is mounted on the mount 70.
Even if it is supported by, the pyroelectric element moves greatly when vibration is applied to the sensor, and this movement may cause an output even though the pyroelectric element does not detect the flame, and this output causes a malfunction.

The present invention has been made to solve the above problems, and there is no possibility that the light receiving element will move or the lead wire will bend due to shock or vibration, and there is no fear of being affected by electromagnetic waves. The purpose is to obtain a fire detector.

[0011]

A radiant fire detector according to the present invention has a bottomed cylindrical main body and an inclined portion connected to the main body and having a diameter reduced upward. A housing formed of a cover provided with a window, a first printed board housed in an inclined portion of the housing, and a second housing connected below the first printed board via a spacer and housed in the housing.
Of the printed circuit board and a light receiving element connected between the first printed circuit board and the light transmitting window of the housing, and at least the light receiving element on the first printed circuit board. This is provided with a preamplifier section for amplifying the output signal of.

Further, in the above radiant fire detector,
The light receiving element is placed on the upper surface of the first printed circuit board, and its lead wire is connected and fixed to the first printed circuit board. A tubular portion provided with a light portion is formed, and a plurality of fins are provided at substantially equal intervals from the side wall of the tubular portion to the inclined portion.

[0013]

The first printed board provided with the light receiving element, the preamplifier section and the like and the second printed board provided with the main amplifier section, the fire discrimination section and the like are vertically arranged via the spacer.
Since it is arranged in steps, it can be easily accommodated in a substantially Mt. Fuji-shaped housing with a narrowed upper part, which shortens the length of the lead wire from the light receiving element to the first printed circuit board, Alternatively, the light receiving element can be directly fixed to the first printed board. Further, since the preamplifier section is provided on the first printed board to which the light receiving element is attached, the distance between the light receiving element and the preamplifier section can be minimized.

Furthermore, when the sensor is attached to or detached from the base,
The attachment / detachment jig is engaged with a plurality of fins provided on the case and rotated.

[0015]

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 includes a cylindrical main body 11 having a bottom plate 12 and a cover 13 coupled to the main body 11 by locking claws.
1 and a cylindrical portion having a diameter smaller than that of the connecting portion formed above the inclined portion and an inclined portion that is reduced in diameter upward from the connecting portion. A transparent window 14 is provided. Reference numeral 15 denotes a plurality of filling portions that are provided so as to project around the transparent window 14 and open downward.

Reference numeral 16 is a window plate made of sapphire as an infrared filter disposed on the light transmitting portion 14 via a packing 17, and 18 is a locking claw which is locked to the filling portion 15 so that the window plate 1
A holding ring for fixing 6 to the translucent window 14, and a filling material 19 such as silicone rubber is charged in the filling portion 15 for waterproofing. Reference numeral 20 is an LED display window provided on the inclined portion of the cover 13, and 21 is 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 portion housed in the housing 10. An outline of the circuit is shown in FIG. 33 is a light receiving element, 4
1 is a preamplifier section having one or more stages of OP amplifiers,
Reference numeral 42 denotes an output resistance, which forms the first circuit section 40. Further, 44 is a main amplifier unit having an OP amplifier and having a sensitivity adjusting function, 45 is a level discriminating unit having a comparison OP amplifier, and 46 and 47 are delay integrating circuits, which are the level discriminating unit 45 and the delaying unit. Integrating circuits 46, 4
7 and the transistor 48 and the Zener diode 49 constitute a fire discrimination unit. 50 is a switching element for outputting a fire signal, 51 and 52 are constant voltage circuits, 53 is a diode bridge for depolarization, 54 is an output terminal, and the second circuit section 43 is formed by these, and the first circuit The portion 40 and the second circuit portion 43 are connected by a conductor 37a.

4 and 5 are a plan view and a side view of a printed circuit board incorporating the above electric circuit. 31 is a small-sized first printed circuit board provided with a first circuit section 40, 32
Is a preamplifier section 4 provided on the first printed circuit board 31.
It is a shield case which covers the circuit components which comprise 1 etc.
33 is mounted on the upper surface of the first printed circuit board 31, and the lead wire inserted in the through hole is the first printed circuit board 3.
1 is a light receiving element such as a pyroelectric element connected to the printed wiring on the lower surface of 1.

Reference numeral 35 denotes a first circuit provided with a second circuit section 43.
Second printed circuit board larger than the printed circuit board 31 of 3
Reference numeral 6 denotes an operation indicator light such as an LED mounted on the second printed circuit board 35, and both printed circuit boards 31 and 35 are electrically coupled by a spacer 37 such as a conductive connecting pin.

Reference numeral 38 is a blade fitting provided on the lower surface of the main body 31, fixed to the terminal of the base provided on the ceiling or the like, and electrically connected. The second printed circuit board 35 is made of a conductive material. It is fixed to the main body 11 with screws 39,
It is connected to the blade fitting 38. The first printed circuit board 31 and the second printed circuit board 35 may be vertically connected by a spacer made of an insulating material, and the printed wirings of both printed circuit boards 31 and 35 may be connected by a lead wire or the like.

The present invention, as described above, is of a relatively small first type.
The light receiving element 33 and the preamplifier section 41 on the printed circuit board 31 of
And a second circuit section 43 including a main amplifier section 44, fire determining sections 45 to 49, and the like on a second printed circuit board 35 larger than the first printed circuit board 31. , These first and second printed circuit boards 3
Since 1, 35 are arranged in upper and lower two stages, both printed circuit boards 3 can be used even in a case where the upper part is narrowed and the volume is smaller than the lower part.
1, 35 can be easily accommodated, and the light receiving element 33 is fixed on the first printed circuit board 31 and connected to the first printed circuit board 31.
It can be connected to the printed circuit board 31 of FIG.

FIG. 6 is a partial sectional view of another embodiment of the present invention. In this embodiment, the light-transmitting window 14 of the cover 13 is provided with a light-shielding wall 14a including a flange portion 14b and a cylindrical portion 14c provided in the center of the flange portion 14b and surrounding the side portion of the light-receiving element 33. By doing so, it is possible to prevent the sunlight transmitted through the transparent window 14 from irradiating the side wall of the light receiving element to heat the light receiving element and output a detection signal to cause a malfunction.

[0023]

As is apparent from the above description, according to the present invention, the first printed circuit board is provided with the first circuit section including the light receiving element and the preamplifier section, and the second printed circuit board is provided with the main amplifier section and the fire. Since the second circuit portion including the discriminating portion and the like is provided and arranged in the upper and lower two stages, the following remarkable effects can be obtained.

(1) Even in an approximately Mt. Fuji-shaped casing with a narrowed upper part, the electric circuit portion can be housed in the casing by bringing the light receiving element close to the translucent window.

(2) Since the length of the lead wire from the light receiving element to the first printed board can be shortened, it is possible to greatly prevent the lead wire from serving as an antenna and picking up an electromagnetic wave.

(3) Since the lead wire can be made short, it is difficult to bend even if it receives an impact, etc. Therefore, it is possible to prevent the position and sensitivity of the light receiving element from being distorted. Also, the mount can be omitted.

(4) Since the light receiving element can be directly fixed to the first printed circuit board, the light receiving element does not move largely as in the conventional case even when the sensor receives vibration or the like. Therefore, even when a pyroelectric element is used as the light receiving element, the occurrence of malfunction due to vibration or the like can be significantly reduced.

(5) Since the electric circuit portion is composed of two printed circuit boards, the electric parts mounted on the printed circuit board can be dispersed. Therefore, the first and second printed circuit boards can be downsized, and the housing that houses them can also be downsized.

(6) Since the preamplifier section can be provided on the first printed circuit board to which the light receiving element is attached and the distance between the light receiving element and the preamplifier section can be minimized, the influence of noise can be greatly suppressed. it can.

(7) When the fin is provided from the side wall of the cylindrical portion of the case to the inclined portion, when the sensor is attached to or detached from the base, the attachment / detachment jig is locked to the fin to rotate the detector. Therefore, it is extremely easy to attach and detach the sensor to and from the base.

[Brief description of drawings]

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

FIG. 2 is a plan view of FIG.

FIG. 3 is a circuit diagram of an embodiment of an electric circuit unit of the present invention.

4 is a plan view of an embodiment of a printed circuit board incorporating the electric circuit unit of FIG.

FIG. 5 is a side view of FIG.

FIG. 6 is a partial cross-sectional view of another embodiment of the present invention.

FIG. 7 is a vertical sectional view of an example of a conventional radiant fire detector.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Housing 11 Main body 12 Bottom plate 13 Cover 14 Transparent window 30 Electric circuit part 31 1st printed circuit board 32 Shield case 33 Light receiving element 35 2nd printed circuit board 37 Spacer 40 1st circuit part 41 Preamplifier part 43 2nd Circuit part

Claims (3)

[Claims] 1. A casing comprising a bottomed cylindrical main body, a cover coupled to the main body and having an inclined portion whose diameter is reduced upward, and a cover having a translucent window on the upper bottom, and the casing. A second printed board housed in the housing and coupled below the first printed board via a first printed board and a spacer housed in the inclined portion of the housing; and a transparent window of the housing. And a first printed circuit board and a light receiving element connected to the first printed circuit board, and a preamplifier section for amplifying at least an output signal of the light receiving element on the first printed circuit board. A radiant fire detector characterized by being provided with. 2. The radiant fire detection system according to claim 1, wherein the light receiving element is placed on the upper surface of the first printed circuit board, and its lead wire is connected to and fixed to the first printed circuit board. vessel. 3. The cover is provided with a tubular portion having a smaller diameter than a lower portion on an upper portion of an inclined portion of the housing and a light transmitting portion on an upper bottom,
The radiant fire detector according to claim 1 or 2, wherein a plurality of fins are provided at substantially equal intervals from the side wall of the tubular portion to the inclined portion.