JP2005122437A - Flame sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a fouling degree measurement test result of high precision. <P>SOLUTION: The flame sensor 1 is equipped with a case 4 whose main body 2 is fitted with a main-body cover 3 with an opening, a circuit board 5 put in the case 4, a light reception window 7 which is provided to the case 4 to block the opening, a light receiving element 8 which is provided in the case 4 opposite the light reception window 7, a light emitting element 10 for fouling degree measurement which is provided opposite the light reception window 7, and a light receiving element 22 for fouling degree measurement which faces the light emitting element 10 across the light reception window 7, the light receiving element 22 for fouling degree measurement is arranged outside an element storage part 13. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a flame detector for detecting a fire, and more particularly to a flame detector having a function of measuring the degree of contamination of a light receiving window.

  The flame detector is provided with a light receiving window, and infrared light or the like emitted from the flame passes through the light receiving window and is received by the light receiving element. For this reason, if the light receiving window is contaminated with dust or the like, the infrared rays are hardly transmitted, and it is difficult to perform highly accurate flame detection.

  Therefore, in order to solve the above problem, a light receiving window provided in the approximate center of the main body cover, a test light source for irradiating test light provided in the main body cover, and a rear surface of the light receiving window are provided near the back of the test light source. A fire detector with a contamination degree measurement test function including a light receiving sensor that receives light has been developed (for example, see Patent Document 1).

JP 2002-358583 A

  In this fire detector, the test light from the test light source passes through the light receiving window and is received by the light receiving sensor, and when the output level at that time becomes a predetermined percentage of the initial level, for example, 85% or less, the light is received. It is determined that the window is dirty.

  In conventional flame detectors, the light receiving sensor that receives the test light (light receiving element for measuring the degree of contamination) is also used as the light receiving sensor for fire monitoring and is provided inside the light receiving window. Sometimes, the light receiving element for measuring the degree of contamination receives not only the test light from the light emitting element for measuring the degree of contamination but also external light from the fire monitoring area. For this reason, the output level is saturated or becomes an output level including an external light component due to the influence of external light, and an accurate contamination degree measurement test result cannot be obtained.

  In view of the above circumstances, an object of the present invention is to obtain a highly accurate contamination degree measurement test result.

  This invention is incident from the opening through a case made of a main body and a body cover with an opening connected to the main body, a circuit board accommodated in the case, and a light receiving window made of a material that transmits infrared rays. A light receiving element that receives infrared rays emitted from the flame, a contamination measuring light emitting element that emits test light for performing a contamination degree measuring test of the light receiving window, and the test light through the light receiving window. A flame detector comprising: a light receiving element for measuring the degree of contamination that receives light; the light receiving element for measuring the degree of contamination is mounted on a circuit board accommodated in the case, avoiding the opening. It is characterized by.

  An element housing comprising a light receiving element holder for housing the contamination degree measuring light receiving element of the present invention, a light receiving window disposed on a front surface of the holder, and a light receiving element cover for fixing the light receiving window to the holder. Mounted on the circuit board so as to block the opening, the contamination degree measuring light receiving element is disposed outside the element accommodating portion, and the element accommodating portion is connected to the contamination degree measuring light receiving element. The facing portion is a visible light cut member.

  The contamination degree measuring light emitting element and the contamination degree measuring light receiving element of the present invention are mounted on the circuit board so as to face each other through the light receiving window, and the contamination degree measuring light emitting element includes the main body cover. It is arranged on the inner surface side of the side wall of the concave portion formed in the above, and the contamination degree measuring light receiving element is arranged almost on the surface of the circuit board.

  Since the light receiving element for contamination degree measurement according to the present invention is mounted on the circuit board accommodated in the case, avoiding the inside of the opening, the external light incident area at the time of the contamination degree measurement test is significantly larger than the conventional one. It is narrower. For this reason, it becomes difficult to receive external light other than the test light from the contamination degree measurement light emitting element, and therefore, an accurate contamination degree measurement test result can be obtained as compared with the conventional example.

  Since the portion of the element housing portion facing the light receiving element for measuring the degree of contamination is a visible light cut member, the light receiving element for measuring the degree of contamination further includes visible light other than the test light from the light emitting element for measuring the degree of contamination. Since it becomes difficult to receive the light component, a more accurate contamination degree measurement test result can be obtained.

  The contamination degree measuring light emitting element of the present invention is disposed on the inner side of the side wall of the concave portion formed in the cover, and the contamination degree measuring light receiving element is disposed substantially on the surface of the circuit board. The maximum height difference that can be taken in the case can be taken, and the incident angle of the test light to the light receiving window can be minimized. Therefore, the transmittance of the test light in the light receiving window is increased, and the S / N at the output level of the contamination degree measuring light receiving element can be increased. Therefore, a more accurate contamination degree measurement test result can be obtained.

A first embodiment of the present invention will be described with reference to FIGS.
The flame detector 1 includes a case 4 including a main body 2 and a main body cover 3, and is attached to a ceiling surface or the like by being coupled to an attachment base by a blade fitting (not shown).

  A light receiving element 8 is mounted on the circuit board 5 accommodated in the case 4, and an operation check lamp 9 and a pollution degree measuring light emitting element 10 are mounted close to each other.

  The main body cover 3 is formed in a frustoconical shape, and an opening 6 formed by a bottom wall 6c having an opening and a side wall 6a is formed at the center of the concave portion. Further, the body cover 3 is formed with a cap fitting portion 11, which is fitted with the cap fitting portion 11 and made of a methacrylic resin material that accommodates the operation check lamp 9 and the lightness measuring element 10 for measuring the degree of contamination. A transparent translucent cap 11C is provided.

  The light receiving element 8 is housed in the light receiving element housing portion 13, and is mounted on the circuit board 5 so that the light receiving portion 8 a is positioned relative to the opening 6 of the main body cover 3. The light receiving element accommodating portion 13 surrounds the light receiving element 8 and has a cylindrical light receiving element holder 15 that fixes the band pass filter 14 at a relative position with respect to the light receiving portion 8a of the light receiving element 8, and the light receiving element holder 15 A transparent cylindrical light receiving element made of a methacrylic resin material, in which a light receiving window 7 disposed in front of the light receiving element 7 and a light receiving element holder 15 are housed and which fixes the light receiving window 7 at a relative position with respect to the light receiving portion 8a of the light receiving element 8. And a cover 16.

Since the light receiving element cover 16 is in contact with the inner surface of the bottom wall 6c of the opening 6 of the concave portion, the opening of the opening 6 is in a state where it is blocked by the element accommodating portion 13. ing. The light receiving element accommodating portion 13 is engaged 17 by a plurality of locking holes 16b and projections 15c (only one set shown in FIG. 1) corresponding to the light receiving element cover 16 and the light receiving element holder 15, and the light receiving element holder 15 Is attached to the circuit board 5 by engaging (not shown) with the circuit board 5. The band-pass filter 14 has a property of transmitting only light within a specific wavelength band, and in the present embodiment, only the infrared light in the wavelength band of the CO ₂ resonance radiation emitted from the flame is used. Is used to transmit the light. The light receiving window 7 is made of a material that transmits infrared rays, for example, sapphire glass.

  Thereby, in the flame detector 1, infrared rays from the flame pass through the light receiving window 7 and the band pass filter 14 from the opening 6 of the body cover 3 and are received by the light receiving portion 8 a of the light receiving element 8. The light receiving element 8 can detect the occurrence of the flame by detecting the infrared rays.

  The translucent cap 11 </ b> C accommodates the operation check lamp 9, the first storage chamber 19 having the first light transmission window 18 for the operation check lamp 9, and the pollution degree measuring light emitting element 10. And a second storage chamber 21 having a second light transmission window 20 for the measurement light emitting element 10. The first storage chamber 19 has a substantially box shape having no surface on the circuit board 5 side, and the second storage chamber 21 has a substantially box shape having no surface on the circuit board 5 side and the surface side of the main body cover 3. Is. A surface of the second housing chamber 21 on the surface side of the main body cover 3 is closed by the main body cover 3.

  In the translucent cap 11C, the first translucent window 18 is formed in a quadrangular pyramid shape and the surface is formed in a satin-like shape, and is provided so as to protrude outward from the surface of the main body cover 3. The translucent window 20 is formed on the side wall 21 b of the second storage chamber 21 and is provided facing the opening 6 of the main body cover 3.

  The operation check lamp 9 is mounted with its lead wire portion 9b directly attached to the circuit board 5, and its light emitting portion 9a is located in the first accommodating chamber 19 of the translucent cap 11C. The pollution degree measuring light-emitting element 10 is a light-emitting diode that emits test light in the near-infrared wavelength band, and is mounted on the circuit board 5 via a socket 10c. The light emitting part 10a of the light emitting element 10 is located in the second storage chamber 21 in the vicinity of the lowermost back side of the main body cover 3, and the lead wire part 10b is bent so that the light emitting part 10a is While being bent at a predetermined bending angle, for example, 18 degrees, it is directed to the light receiving window 7 and is directed to a direction in which the contamination degree measuring light receiving element 22 described later and the optical axis of each other face each other.

The second storage chamber 21 in which the contamination degree measuring light emitting element 10 is accommodated is provided with a light emitting part holder 21a for accommodating the light emitting part 10a of the contamination degree measuring light emitting element 10 at the tip thereof. The light emitting unit holder 21 a is formed by a side wall 21 b and an inclined surface 21 c that is provided on the back side of the lowermost surface of the main body cover 3 and extends along a predetermined bending angle of the light emitting unit 10 a.
And the position of the light emission part 10a is controlled because the side wall 21b is located in the front side of the light emission part 10a, and the inclined surface 21c is located in the back side of the light emission part 10a. The light emitting unit 10a is disposed on the inner surface side of the concave side wall 6a when viewed from the body cover 3.

The contamination degree measuring light receiving element 22 that receives light from the contamination degree measuring light emitting element 10 is mounted directly attached to the circuit board 5 at a position avoiding the inside of the opening 6.
Here, the position avoiding the opening is a position that is not relative to the opening, and refers to a region in which external light is less likely to enter from the opening than in the conventional example, for example, outside the element housing portion 13. This light receiving element 22 is a Si photodiode having sensitivity in a wavelength band from visible light to near infrared, and its light receiving surface is constituted by a visible light cut member. The light receiving element 22 is positioned on the opposite side of the contamination measuring light emitting element 10 via the element housing portion 13 in the circuit board 5, and the lead wire portion 22b is further bent so that the light receiving portion 22a It is bent at a bending angle so that the pollution degree measuring light emitting element 10 and the optical axis of each other face each other.

  The predetermined bending angle of the light emitting portion 10a may be defined by bending the lead wire portion 10b by jig bending, or the light emitting portion 10a emits light during assembly without being bent by the jig. The inclined surface 21c of the light-emitting part holder 21a, that is, the inclined surface along the predetermined bending angle of the light-emitting part 10a may be regulated by being accommodated in the light-emitting part holder 21a while being slid. The degree of contamination is measured by providing or attaching a member that regulates to face the light emitting part 10a of the contamination measuring light emitting element 10 on the outside of the circuit board 5 or the light receiving element accommodating part 13. The light receiving part 22a of the light receiving element 22 may be opposed to the light emitting part 10a of the contamination degree measuring light emitting element 10.

  In addition, when the lead wire portion 10b is bent by jig bending to define the bending angle of the light emitting portion 10a, a reaction force is generated, so it is conceivable that the bending angle becomes shallow due to a change with time, but the light emitting portion 10a. The change from the predetermined bending angle can be prevented by the inclined surface 21c along the predetermined bending angle. In addition, the inclined surface 21 c of the light emitting unit holder 21 a is provided on the back side of the lowermost surface of the main body cover 3, but it may be formed in the second storage chamber 21 of the translucent cap 11.

Next, the operation of the present embodiment will be described.
During fire monitoring:
As shown in FIG. 3, the light receiving element 8 monitors the flame monitoring area 8 </ b> A through the light receiving window 7. This flame monitoring area 8A is regulated by an inner wall 6L formed on the front end side of the side wall 6a of the opening 6 and an open end wall 6B of the bottom wall 6c, and is a frustoconical area. When a fire occurs in the flame monitoring area 8A, the infrared rays generated by the fire pass through the opening of the opening 6, the light receiving window 7, and the band pass filter 14, and are received by the light receiving element 8, so that the fire can be detected. .

During a light-receiving window contamination degree measurement test:
When power is supplied to the light emitting element 10 for measuring the degree of measurement, test light in the near infrared wavelength band is generated, and the test light is transmitted through the second light transmitting window 20, the light receiving window 7, and the light receiving element cover 16 of the light transmitting cap 11C. The light passes through the window 16a (FIG. 1) and is received by the light receiving element 22 for measuring the degree of contamination.

At this time, since the light receiving element 22 is disposed outside the light receiving element cover 16, that is, at a position avoiding the opening of the opening 6, the outside light incident area 22A is the flame monitoring area 8A. The direction is different and the area is also narrowed. Therefore, since external light is less likely to enter the contamination degree measuring light receiving element 22 as compared to the conventional example, an accurate contamination degree measurement test result can be obtained.
The light receiving element accommodating portion 13 has a windproof function and can prevent the light receiving element 8 from being affected by the outside air, so that a protective member as in the conventional example is not necessary.

  Further, the second light transmission window 20 through which the light of the pollution degree measuring light emitting element 10 is transmitted is formed on the side wall 21 b of the second storage chamber 21 and is provided facing the concave opening 6 of the main body cover 3. ing. For this reason, dust or the like hardly adheres and the transmittance of the test light does not easily decrease, so that the degree of contamination of the light receiving window 7 can be accurately measured.

A second embodiment of the present invention will be described with reference to FIG. 4. The same reference numerals as those in FIGS. 1 to 3 have the same names and functions.
The differences between this embodiment and the first embodiment are as follows.
(1): The visible light cut member 25 is provided in the notch 15a (FIGS. 1 and 4) of the light receiving element holder 15, and the test light is incident on the light receiving element 22 for measuring the degree of contamination through the cut member 25. Thereby, since the visible light component of external light can be cut, a more accurate contamination degree measurement test result can be obtained.
As the cut member 25, for example, polycarbonate (trade name “Iupilon N-5 L903E” manufactured by Mitsubishi Engineering Plastics Co., Ltd.) is used.

  Instead of providing the visible light cut member in the cutout portion 15a, the cutout portion of the holder 15 may be eliminated to form the entire holder with a visible cut member, or the light receiving element cover may be used as a visible light cut member. That is, in the element accommodating part 13, the part facing the contamination degree measuring light receiving element 22 may be a visible light cut member.

  (2) The light receiving element 22 is moved in a direction away from the light receiving window 7 and disposed at a position 22 </ b> S near the side surface of the case 4. In this way, the external light incident area 22SA becomes narrower than the external light incident area 22S of the above-described embodiment, so that a more accurate contamination degree measurement test result can be obtained.

  (3) The light receiving element 22 is a surface mount type photodiode. In this way, since the height difference between the light emitting element 10 and the light receiving element 22 can be increased, the incident angle of the test light at the light receiving window 7 can be reduced. Therefore, since the reflectance value of the test light at the light receiving window 7 can be reduced, that is, the transmittance of the test light can be increased, the s / n ratio at the output level of the contamination degree measuring element can be increased. Since it can be enlarged, a more accurate contamination degree measurement test result can be obtained.

It is a figure of the flame detector which shows 1st Embodiment of this invention, and is the II sectional schematic longitudinal cross-sectional view of FIG. It is a top view of the flame detector of this invention. It is a figure which shows the flame monitoring area | region and external light incident area | region in FIG. It is a schematic longitudinal cross-sectional view of the flame detector which shows 2nd Embodiment of this invention, and is a figure corresponding to FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Flame detector 2 Main body 3 Main body cover 4 Case 5 Circuit board 6 Opening part 7 Light receiving window 8 Light receiving element 10 Light emitting element for contamination degree measurement 13 Light receiving element accommodating part 22 Light receiving element for contamination degree measurement

Claims (3)

A case composed of a main body and a main body cover with an opening connected to the main body, a circuit board housed in the case, and a flame incident from the opening through a light receiving window made of a material that transmits infrared rays. A light receiving element that receives emitted infrared light, a light emitting element for measuring the degree of contamination that emits test light for performing a degree of contamination measurement test of the light receiving window, and a degree of contamination that receives the test light through the light receiving window A flame detector comprising: a light receiving element for measurement;
The flame detector is mounted on the circuit board accommodated in the case, avoiding the inside of the opening. A light receiving element holder that houses the light receiving element for measuring the degree of contamination inside, a light receiving element disposed on the front surface of the holder, and a light receiving element cover that fixes the light receiving window to the holder. It is mounted on the circuit board so as to close the opening,
The contamination degree measuring light receiving element is disposed outside the element accommodating portion,
The flame detector according to claim 1, wherein the element housing portion uses a visible light cut member at a portion facing the contamination measuring light receiving element. The contamination degree measuring light emitting element and the contamination degree measuring light receiving element are mounted on the circuit board so as to face each other through the light receiving window,
The pollution degree measuring light emitting element is disposed on the inner surface of the side wall of the concave portion formed in the body cover,
The flame detector according to claim 1, wherein the contamination measuring light-receiving element is disposed substantially on a surface of the circuit board.

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