Heat sensor

Abstract

To improve the visibility of an operation display lamp in a heat sensor using a thermistor as a heat sensing element.SOLUTION: A heat sensor in which a circuit board on which a thermistor and components constituting a detection circuit are mounted is housed inside a housing including a bottomed cylindrical main body case and an outer cover member that covers an opening side of the main body case, an opening is formed in the outer cover member at a position corresponding to the thermistor, and a protector portion that includes an inlet through which outside air can flow in, forms a space that a tip of the thermistor faces, and covers the opening is provided, the heat sensor comprising: The surface of the thermistor is colored with a color that easily reflects the emission color of the indicator lamp, the housing is provided with the operation indicator lamp capable of emitting light from a part of the outer cover member, the operation indicator lamp includes the light emitting portion disposed around the thermistor, and the thermistor and the light emitting portion are disposed such that a part of the light emitted from the light emitting portion is emitted to the surface of the thermistor.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a heat detector that uses a thermistor as a heat sensing element (sensor). [Background technology]

[0002] Heat detectors that use thermistors are generally configured to detect the occurrence of a fire by placing a thermistor as a heat-sensing element in the center of a dome-shaped housing, and attaching the housing to the ceiling surface of a building so that the thermistor faces downward. Generally, heat detectors using thermistors often have a white-based housing (case) so that they are not conspicuous when not triggering an alarm. On the other hand, the operation indicator light that lights up or flashes when a fire is detected must be highly visible, for example, when installed on a ceiling. For this reason, some detectors have a window in part of the detector body (housing) so that the light-emitting display of the operation indicator light can be seen through the window (see, for example, Patent Document 1). Some detectors also have a bullet-shaped LED (light-emitting diode) whose head is directly exposed on the surface of the detector body (see, for example, Figure 9 of Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-175860 [Patent Document 2] Japanese Patent Application Publication No. 08-180273 Summary of the Invention [Problem to be solved by the invention]

[0004] Since the ceilings on which heat detectors are installed are often white or white-based, installing a white-based heat detector can make the detector less noticeable. However, many conventional heat detectors use black thermistors, which are mounted facing downward in the center of the housing and are provided with a protector to protect the thermistor. The protector also has radial fins centered on the thermistor to help capture hot air currents. Therefore, while the heat detector itself is inconspicuous, the black thermistor stands out, creating a problem where the heat detector does not blend in with the surrounding colors.

[0005] In addition, in conventional heat detectors, the window for the operation indicator light is often provided on the surface of the detector body outside the protector, but because the display window is relatively small, it can be obstructed by the protector or black thermistor depending on the viewing direction, resulting in poor visibility. Therefore, it is possible to consider forming the protector from a transparent or translucent material, but this results in a configuration in which a protector made of a different material is provided in the center of a heat detector body that is primarily white, which creates the problem of the protector standing out and not blending in with the surrounding color tone.

[0006] The present invention was made in response to the above-mentioned problems, and its purpose is to improve the visibility of the operation indicator light in a heat detector that uses a thermistor as the heat sensing element. Another object of the present invention is to prevent components such as the thermistor and protector from becoming conspicuous in a heat detector that uses a thermistor as a heat sensing element, so that the detector blends in with the installation environment. [Means for solving the problem]

[0007] In order to achieve the above object, the present invention provides: A heat detector in which a circuit board on which a thermistor and components constituting a detection circuit are mounted is housed inside a housing consisting of a cylindrical main body case with a bottom and an outer cover member covering the open side of the main body case, and an opening is formed in the outer cover member at a position corresponding to the thermistor, and a protector part is provided which has an inlet through which outside air can flow in, forms a space facing the tip of the thermistor, and covers the opening, The surface of the thermistor is colored to reflect the color of the light emitted by the indicator light. an operation indicator light capable of emitting light from a part of the outer cover member is disposed on the housing; the operation indicator lamp includes a light-emitting element mounted on the circuit board and a light-emitting portion formed of a light-transmitting material and disposed around the thermistor; the thermistor and the light emitting portion are arranged so that a portion of the light emitted from the light emitting portion is irradiated onto a surface of the thermistor; the light emitting portion is configured by an inner cover having an insertion hole with an inner diameter larger than a diameter of the thermistor, the inner cover is disposed so that a base of the thermistor is positioned within the insertion hole and corresponds to the opening of the outer cover member; The light source is configured so that a portion of the light emitted from the inner cover is irradiated onto the surface of the thermistor.

[0008] With the heat detector configured as described above, a portion of the light emitted from the operation indicator light is irradiated onto the surface of the thermistor, which is colored to easily reflect the light emitted by the indicator light, thereby brightening the thermistor and improving the visibility of the operation indicator light.

[0009] In addition, since the light emitting portion made of a translucent material is arranged around the thermistor, the light emitted from the light emitting portion is irradiated toward the thermistor, making the thermistor brighter, thereby improving the visibility of the operation indicator light when viewed from multiple directions.

[0010] Preferably, the surface of the thermistor is colored white or similar. The outer cover member and the protector portion are made of a white resin. With this configuration, the surface of the heat sensing element and the surfaces of the outer cover member and protector portion are the same color, so the thermistor does not stand out against the housing and the color harmonizes with the surrounding environment.

[0011] Preferably, the inner cover is formed in a cone shape or a flat plate shape that widens from the insertion hole in a direction away from the circuit board. With this configuration, the inner cover protects the thermistor, while some of the light emitted from the inner cover is irradiated onto the surface of the thermistor, making the thermistor brighter, thereby improving the visibility of the operation indicator light.

[0012] Furthermore, it is desirable that a coating of the same color as the surface of the outer cover member is provided on a portion of the front or back surface of the inner cover. With this configuration, the inner cover can be made less noticeable than the housing. [Effects of the Invention]

[0013] The heat detector according to the present invention can improve the visibility of the operation indicator light, and also has the effect of making components such as the thermistor and protector less noticeable in the installation environment. [Brief explanation of the drawings]

[0014] [Figure 1] 1A and 1B show an embodiment of a heat detector according to the present invention, in which (A) is a front cross-sectional view and (B) is a perspective view. [Figure 2] 1A is a front cross-sectional view showing a first modified example of the heat detector of the embodiment of FIG. 1, and FIG. 1B is a front cross-sectional view showing a second modified example. [Figure 3] FIG. 10 is a front cross-sectional view showing another embodiment of a heat detector according to the present invention. [Figure 4]10A and 10B show another example of the configuration of the inner cover, where (A) is a front cross-sectional view, (B) is a bottom view, and (C) is a cross-sectional view showing a modified example. [Figure 5] 10A and 10B show still another example of the inner cover, in which (A) is a front cross-sectional view and (B) is a bottom view. DETAILED DESCRIPTION OF THE INVENTION

[0015] Hereinafter, an embodiment of a heat detector according to the present invention will be described with reference to the drawings. Figure 1 shows an exposed-type heat detector, with Figure 1(A) showing a front cross-sectional view of the heat detector according to the embodiment, and Figure 1(B) showing a perspective view of the heat detector according to the embodiment. 1, the case where the exterior of the detector is white will be described, since the ceiling and wall surfaces are often white, and the operation indicator light emits red light. The heat detector 10 of this embodiment is a detector that uses a thermistor as a heat sensing element and can detect a fire by detecting the change in electrical resistance that occurs when air heated by the heat generated by a fire comes into contact with the thermistor, and is configured to be installed and used on the ceiling surface of a building, etc.

[0016] As shown in Figure 1(A), the heat detector 10 of this embodiment comprises a cylindrical main body case 11 with a bottom and an accommodating recess 11A for accommodating heat-sensing components and which can be connected to a base member attached to the ceiling surface of a building, an outer cover 12 which has a protector part in the center that covers the tip of the thermistor and covers the entire opening side of the main body case 11, and a decorative cover 13 which covers the peripheral part of the outer cover 12 and hides the mounting screws and wiring on the ceiling surface, and the main body case 11 and outer cover 12 form a housing with an internal accommodating space.

[0017] The heat detector 10 of this embodiment also includes a circuit board 14 accommodated in the accommodation recess 11A of the main body case 11, a thermistor 15 mounted on the circuit board 14, and an inner cover 16 having a cylindrical portion 16a with an insertion hole through which the thermistor 15 can be inserted and arranged so that its upper end is in contact with the surface of the circuit board 14, a funnel-shaped portion 16b extending downward from the cylindrical portion 16a, and a flange portion 16c provided at the lower end of the funnel-shaped portion 16b.

[0018] The circuit board 14 is made up of a printed wiring board on whose top and bottom surfaces electronic components 20 such as resistors, capacitors, and ICs (semiconductor integrated circuits) that make up the electronic circuit for fire detection are mounted, and the tips of the lead terminals of the thermistor 15 penetrate the circuit board 14 at approximately the center of the circuit board 14 and protrude from the opposite surface, and are connected by flow soldering or the like. In addition, in the heat detector of this embodiment, the outer cover 12 and the decorative cover 13 are formed of white resin, and the thermistor 15 has a surface coated with paint such as white epoxy resin. In this embodiment, the color of the thermistor 15 is selected to be white as a color that sufficiently reflects red when the operation indicator light emits red light to indicate an abnormality. However, the color is not limited to white, and any color that sufficiently reflects red light and is visible can be used. In this embodiment, the surface portion of the sensor that is visible when the sensor is installed on a ceiling or the like is referred to as the outer cover, and the outer cover 12, decorative cover 13, and protector 12C are collectively referred to as the outer cover members.

[0019] On the other hand, the outer cover 12 has a circular opening 12A formed in its center, at least a portion of which abuts (abuts in an overlapping manner) against the flange portion 16c of the inner cover 16, and a ring-shaped head portion 12B is provided located below the inner cover 16, and the thermistor 15 is arranged so that the head of the thermistor 15 reaches close to the head portion 12B. Furthermore, as shown in Fig. 1(B), a plurality of (e.g., six) columnar partition walls 12C are formed radially between the ring-shaped head portion 12B and the outer cover 12, and openings that function as inlets that allow outside air to flow into the case are provided between these partition walls 12C. The head portion 12B and the partition walls 12C form a protector portion. The partition walls 12C may be plate-shaped.

[0020] In the heat detector of this embodiment, the inner cover 16 having the cone-shaped portion 16b is made of a light-transmitting material such as polycarbonate resin, and an LED (light-emitting diode) 17 for indicating an operating state is mounted at a position corresponding to the flange portion 16c of the inner cover 16. The LED 17 emits light of a color (e.g., red) different from that of the housing. A light-guiding portion 16e formed as a recess is provided at a position facing the LED 17 on the back surface of the flange portion 16c of the inner cover 16.

[0021] A light-guiding section 16e formed as a recess is provided on the rear surface of the flange 16c of the inner cover 16, facing the LED 17. The flange also has a light-reflecting section 16f on the surface opposite the light-guiding section 16e (the bottom surface in the figure). The light-reflecting section 16f is configured as a recess (groove) with a V-shaped cross section when viewed from the side. The light from the LED 17 that enters through the light-guiding section 16e is reflected by the light-reflecting section 16f and guided to the entire cone-shaped section 16b of the inner cover 16. The light is then emitted from the cone-shaped section 16b, thereby indicating that the sensor is activated. The number of LEDs 17 is not limited to one, and two or more may be provided.

[0022] Furthermore, in the heat detector of this embodiment, the light emitted from the mortar-shaped portion 16b and the flange portion 16c of the inner cover 16 hits the surface of the central white thermistor 15 and is reflected, allowing the thermistor 15 to also function as a display portion, thereby increasing the apparent area of ​​the luminous display and widening the visible direction. Specifically, if the thermistor 15 is a typical black color, it will partially obscure the cone-shaped portion 16b of the inner cover 16, and the light from the operation indicator that hits the thermistor 15 will be absorbed, reducing the amount of light. However, if the surface of the thermistor 15 is a color that easily reflects the light emitted from the indicator, such as white, the light emitted from the cone-shaped portion 16b will hit and reflect off the surface of the thermistor 15, preventing a reduction in the amount of light and making the light-emitting state more visible. It is preferable to give the surface of the thermistor 15 a matte finish (a process that diffuses reflection) rather than a glossy finish. This causes the light from the cone-shaped portion 16b and the flange portion 16c to be diffusely reflected by the surface of the thermistor 15, making the light-emitting state more visible.

[0023] Furthermore, the heat detector of this embodiment employs a structure in which the inside of cylindrical portion 16a of inner cover 16 is filled with resin 19. This allows high-pressure air to enter the housing (the circuit board storage space inside main body case 11) through a hole formed in the ceiling surface for passing wiring, etc., and then flow out through the gap between cylindrical portion 16a of inner cover 16 and thermistor 15, creating a cylindrical airflow layer around thermistor 15. This airflow can prevent the inflow of hot air to thermistor 15 from being obstructed, or water from adhering to thermistor 15, which can facilitate the accumulation of dust and reduce the heat detection function. Furthermore, by using a white resin as the filling resin 19, the color of the inside of cylindrical portion 16a (for example, the color of the circuit board surface) is covered by the resin when viewed from the outside. As shown in FIG. 2(A), the inner cover 16 may have a shape in which the cylindrical portion 16a is elongated, the mortar-shaped portion 16b is eliminated, and the flange portion 16c is directly connected to the cylindrical portion 16a.

[0024] Alternatively, instead of facing the flange 16c of the inner cover 16, a circular window (a round window) for the operation indicator may be provided on the flat surface of the outer cover 12, as shown in FIG. 2(B), with the top of the bullet-shaped LED 17 exposed through the window. By disposing the bullet-shaped LED 17 in this manner and setting the height of the white thermistor 15 so that it is within the optical path of the light emitted from the LED 17 and spread by the convex lens at the top, the light from the LED 17 is reflected by the surface of the thermistor 15, allowing it to function as part of the operation indicator. Instead of having the top of the bullet-shaped LED 17 protrude beyond the flat surface of the outer cover 12, a flat or convex lens may be provided in the operation indicator window of the outer cover 12. While a flat window would narrow the spread angle of the light, providing a convex lens increases the spread angle of the light, allowing it to be reflected even if the thermistor 15 is low in height.

[0025] Furthermore, the surface of the circuit board 14 (the underside in FIG. 1 ) may be coated with a white resist or insulating paint, or may be silk-screened in white. Similarly, the surfaces of the mounted components 20 may be painted white. If the translucent material of the inner cover 16 is highly transparent, the circuit board 14 and mounted components may be visible through the inner cover 16, and the color of the board surface may be visible through the opening in the outer cover 12, or the opening may appear dark. However, by coloring the surfaces of the circuit board 14 and mounted components 20 white, the opening in the outer cover 12 can be brightened, making the entire sensor appear uniformly white. In this case, as described below, it is possible to use a microstructure processing method for the translucent material that can guide light from the LED when an alarm is activated and diffuse it into the surrounding area.

[0026] Next, another embodiment of the heat detector will be described with reference to FIG. Figure 3 shows an embedded type heat detector, and the heat detector 10 of this embodiment does not have the decorative cover 13 of the exposed type heat detector 10 of the embodiment shown in Figure 1, and instead has a cylindrical main body case 11 with a bottom, an outer cover 12 which has a protector part in the center that covers the tip of the thermistor and covers the entire opening side of the main body case 11, and the main body case 11 and outer cover 12 form a housing having an internal storage space, and an inner cover 16 which has a cylindrical part 16a, a funnel-shaped part 16b and a flange part 16c and protects the thermistor 15 is housed within the housing.

[0027] The heat detector of this embodiment is also described as an example in which the outer cover 12 is made of white resin, and the thermistor 15 mounted on the circuit board 14 has a surface coated with paint such as white epoxy resin. Furthermore, the inner cover 16 is formed of a translucent material, and a cylindrical light-guiding section 16e that protrudes toward the circuit board 14 is formed on the flange section 16c. A low-profile LED chip 17 is surface-mounted on the circuit board 14 so as to face the end face of this light-guiding section 16e. Light emitted from the LED chip 17 passes through the light-guiding section 16e and is guided to the flange section 16c of the inner cover 16, where it is reflected by the light-reflecting section 16f formed there, and is guided to the entire funnel-shaped section 16b of the inner cover 16. Light is then emitted from the funnel-shaped section 16b, thereby indicating that the sensor is in operation.

[0028] Furthermore, the inner cover 16 is provided with three locking pieces 16d formed to protrude vertically upward from the cone-shaped portion 16b (one of the three locking pieces 16d is shown in FIG. 3). A claw portion is formed at the tip of each locking piece 16d, and this claw portion engages with an engagement hole 14a formed in the circuit board 14, thereby connecting the inner cover 16 to the circuit board 14. The number of locking pieces 16d is not necessarily three; two may also be used. Furthermore, the locking piece 16d may be provided on the flange portion 16c instead of on the cone-shaped portion 16b. Furthermore, in the heat detector of this embodiment, resin 19 is filled inside cylindrical portion 16a of inner cover 16 to prevent a decrease in the heat detection function of the thermistor 15. The filled resin may be white or another color, but if the housing color is white, the resin is preferably white. Also, if the surrounding environment, such as the ceiling, is a color other than white, the surface of the filled resin may be painted white. In this case, the color of the housing should also be matched.

[0029] Furthermore, the surface of the circuit board 14 (the underside in FIG. 3 ) may be coated with a white resist or insulating paint, or may be silk-screened in white. Similarly, the surfaces of the mounted components 20 may be painted white. If the light-transmitting material of the inner cover 16 is highly transparent, the circuit board 14 and mounted components may be visible through the inner cover 16, and the color of the board surface may be visible through the opening in the outer cover 12, or the opening may appear dark. However, by coloring the surfaces of the circuit board 14 and mounted components white, the opening in the outer cover 12 can be brightened, and the entire sensor can appear to be a uniform white color.

[0030] Next, other configuration examples of the inner cover 16 described in the embodiment of Figures 1 and 3 will be described with reference to Figures 4 and 5. Of these, the inner cover 16 of Figure 4 has a coating 18 formed by applying white paint to the surface of the mortar-shaped portion 16b except for the outer periphery. Figure 4(A) is a cross-sectional view of the inner cover 16, and Figure 4(B) is a bottom view of the inner cover 16. In this embodiment, LED light incident through cylindrical light-guiding portion 16e is reflected by light-reflecting portion 16f, spreads horizontally along flange portion 16c, and is emitted from outer annular portion R of coating 18 on the surface of bowl-shaped portion 16b of inner cover 16. Light-reflecting portion 16f is formed as a groove with a V-shaped cross section when viewed from the direction of arrow C in Figure 4(B).

[0031] In a detector to which this embodiment is applied, the light emitted from the annular portion spreads outward through the gaps in the pillars of the protector, and part of the light is reflected by the surface of the white thermistor 15. This makes it easier to visually confirm the lighting state of the operation indicator light. The white coating 18 may be formed on the back surface of the cone-shaped portion 16b instead of on the front surface, or a white film may be attached instead of being formed by applying paint. In this case, a white coating may also be simultaneously formed on the surface of the resin 19 filled inside the cylindrical portion 16a of the inner cover 16. The filled resin may also be formed by molding a two-color resin consisting of white and an opaque white color, or a two-color resin consisting of white and a transparent color. The color of the coating 18 is not limited to white, and may be any color based on white. Instead of forming a white coating 18, a structure (for example, numerous fine grooves) capable of reflecting light guided inside may be formed. If a white coating is formed on the back surface of the funnel-shaped portion 16b, it will appear white during monitoring (when the operation indicator light is off), but when an alarm is issued (when the operation indicator light is on), LED light will be emitted from the entire inside of the funnel-shaped portion, allowing sufficient light to be irradiated onto the thermistor 15, and the reflection of the white thermistor will create a state where visibility is good when the operation is indicated.

[0032] 4(A), the diameter of opening 12A of outer cover 12 may be made larger than the inner diameter of flange 16c of inner cover 16, thereby exposing a portion of the inside of flange 16c and allowing the LED light to exit from this annular portion. In this case, by forming a convex portion on the flat portion of flange 16c on the inside of opening 12A, the area through which light can exit from inner cover 16 to the surface of white thermistor 15 is increased, allowing the light from LED 17 to be reliably irradiated onto and reflected by the surface of white thermistor 15. As explained above, the white coating on the front and back surfaces of the cone-shaped portion 16b may be formed simultaneously. In this case, the area over which light transmitted through the translucent inner cover 16 is emitted to the outside can be narrowed, thereby providing a sufficient amount of light for use as an operation indicator. 4(C), locking piece 16d for fastening inner cover 16 to circuit board 14 may be provided on flange portion 16c instead of cone-shaped portion 16b. In addition, the end face of light-guiding portion 16e may be formed in a concave shape to make it easier to collect light from LEDs 17.

[0033] The inner cover 16 shown in FIG. 5 differs from the inner cover 16 of the embodiment shown in FIG. 4 in that a rib-like light-emitting portion 16g that protrudes downward is provided along the outer peripheral edge of the flange portion 16c. In addition, due to the provision of light output section 16g, light reflecting section 16f formed on the surface of flange section 16c corresponding to light guide section 16e is also formed to form a V shape when cross-sectioned in the vertical direction so as to reflect light from light guide section 16e outward, i.e., toward light output section 16g, which is also different from the inner cover 16 of the embodiment in Figure 4.

[0034] The light output portion 16g has a ring shape when viewed from below, as shown in Fig. 5(B). The light reflecting portion 16f is formed as a groove having a V-shaped cross section when viewed from the direction of arrow C in Fig. 5(B), similar to the embodiment in Fig. 4. Furthermore, in conjunction with the provision of a rib-shaped light-emitting portion 16g that protrudes downward along the outer peripheral edge of the flange portion 16c, a slit 12e is formed in the outer cover 12, as shown in Fig. 5(A), and the light-emitting portion 16g is fitted into this slit 12e so that its head faces the surface of the outer cover 12. The slit 12e has a ring shape in plan view corresponding to the light-emitting portion 16g.

[0035] As shown in FIG. 5(A), the head of the light-emitting portion 16g is formed to bulge downward, so that light is emitted from the light-emitting portion 16g while spreading due to a lens effect. A portion of the light that travels inward is irradiated and reflected by the thermistor 15, which has a white surface and is disposed inside the inner cover 16. In the inner cover 16 shown in FIG. 5, the position of the light-emitting portion 16g is located outside the columnar partition wall 12C that constitutes the protector portion, but it may be formed so that it overlaps with or is located inside the partition wall 12C. Instead of bulging, the head of the light-emitting portion 16g may be flat.

[0036] In a heat detector equipped with the inner cover 16 of this embodiment configured as described above, when the LED 17 is turned on while the detector is installed on the ceiling of a building, the entire conical portion 16b of the inner cover 16 and the ring-shaped light-emitting portion 16g emit light, and the light is visible from any direction, i.e., 360°, between the multiple partition walls 12C, so there is no directionality in visibility and the total light-emitting area is larger than that of the heat detector of the previous embodiment. Furthermore, the light emitted from the light-emitting portion 16g illuminates the side surface of the partition wall 12C and the white thermistor 15, further improving visibility.

[0037] From the above explanation, it can be seen that the sensor of the above embodiment has the following characteristics: the thermistor 15 and the outer cover 12 (including the decorative cover 13) are similar in color; the LED 15 emits an emissive color that is different from that of the thermistor 15 and the outer cover 12; the inner cover 16 or the protector (12B, 12C) and thermistor 15 guide the emissive color of the LED 17; and a thermistor is provided that is similar in color to the outer cover and that easily reflects the emissive color of the LED.

[0038] Although the present invention has been described above based on the embodiments, the present invention is not limited to the above embodiments. For example, in the above embodiments, the inner cover 16 is formed of a light-transmitting material and configured so that light from the LED 17 is guided to the flange 16c of the inner cover 16 and emits light, but the protector portion may be formed separately from the outer cover 12 and made of a light-transmitting material that is opaque or structurally processed to be able to reflect light, and the light from the LED 17 may be guided to the entire protector portion via the partition wall 12C arranged directly above the LED 17 and emit light.

[0039] In this case, if the protector were made of a transparent material, it would look different from the white outer cover 12. Therefore, it is preferable to form the protector from a translucent material that is the same color as the case and that contains fine particles of the same color (e.g., white) as the case color, which diffusely reflects light. This allows the protector to have a hue similar to the case color when the LED 17 is off, unifying the entire detector with a similar color, making the heat detector less noticeable when installed on a ceiling. Furthermore, if the protector is made of a translucent material that has been structurally processed to reflect light, the case color is transmitted as a background color when not transmitting light, and the luminous color is emitted when transmitting light, making the entire detector a similar color and making the heat detector less noticeable when installed on a ceiling. In addition, when the operation indicator light is lit, the operation indication can be displayed in a highly visible manner. Therefore, when monitoring, the color can be made to blend in with the surrounding environment so as not to stand out, and when emitting light, the light-emitting part can be made to stand out as much as possible. [Explanation of symbols]

[0040] 10 heat detector 11 Main unit case 12 Outer cover 13 Makeup cover 14 Circuit Board 15 Thermistor (heat-sensing element) 16 Inner cover 16a Cylindrical part 16b Funnel-shaped part 16c Tsubabe 16d Locking piece 16e Light guide part 16f Reflective part 17 LED (Light emitting element) 18 Film 19 Filling resin

Claims

1. A heat detector in which a circuit board on which a thermistor and components constituting a detection circuit are mounted is housed inside a housing consisting of a cylindrical main body case with a bottom and an outer cover member covering the open side of the main body case, and an opening is formed in the outer cover member at a position corresponding to the thermistor, and a protector part is provided which has an inlet through which outside air can flow in, forms a space facing the tip of the thermistor, and covers the opening, The surface of the thermistor is colored to reflect the color of the light emitted by the indicator light. an operation indicator light capable of emitting light from a part of the outer cover member is disposed on the housing; the operation indicator lamp includes a light-emitting element mounted on the circuit board and a light-emitting portion formed of a light-transmitting material and disposed around the thermistor; the thermistor and the light emitting portion are arranged so that a portion of the light emitted from the light emitting portion is irradiated onto a surface of the thermistor; the light emitting portion is configured by an inner cover having an insertion hole with an inner diameter larger than a diameter of the thermistor, the inner cover is disposed so that a base of the thermistor is positioned within the insertion hole and corresponds to the opening of the outer cover member; A heat detector characterized in that a part of the light emitted from the inner cover is irradiated onto the surface of the thermistor.

2. The surface of the thermistor is colored whitish, 2. The heat detector according to claim 1, wherein the outer cover member and the protector portion are made of a white resin.

3. 3. The heat detector according to claim 2, wherein the inner cover is formed in a cone shape or a flat plate shape that widens from the insertion hole in a direction away from the circuit board.

4. 4. The heat detector according to claim 3, wherein a coating of the same color as the surface of the outer cover member is provided on a part of the front or rear surface of the inner cover member.

Images