Heat sensor

Abstract

To improve visibility of an actuation indicator lamp in a heat sensor using a thermistor as a heat sensing element.SOLUTION: In a heat sensor, a circuit board mounting a thermistor and components constituting a detection circuit thereon is stored inside of a housing consisting of a bottomed cylindrical body case and an outer cover member covering an opening side of the body case. An opening is formed at a position corresponding to the thermistor in the outer cover member, and provided is a protector part including an inflow port through which outside air can flow in, forming a space to which a tip end of the thermistor is opposed, and covering the opening. A surface of the thermistor is colored in a color in which a light-emitting color of the indicator lamp is easy to be reflected, an actuation indicator lamp capable of emitting light from a portion of the outer cover member is disposed in the housing. The actuation indicator lamp includes a light-emitting part disposed around the thermistor, and the thermistor and the light-emitting part are disposed in such a manner that the surface of the thermistor is irradiated with a portion of light emitted from the light-emitting part.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 disposing 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 with the thermistor facing downwards. Generally, heat detectors using thermistors are often designed with 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 is required to have good visibility when installed on a ceiling surface, for example. For this reason, a window is provided in part of the detector body (housing), and the light-emitting display of the operation indicator light can be seen through the window (for example, Patent Document 1). There are also detectors that are configured so that the head of a bullet-shaped LED (light-emitting diode) is directly exposed on the surface of the detector body (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 ceiling surface on which the heat detector is installed is often white or a white-based color, installing a heat detector with a white base color makes the heat detector less noticeable. However, many conventional heat detectors use black thermistors, and the thermistor is arranged in the center of the housing facing downwards, and a protector is provided to protect the thermistor. In addition, the protector has radial fins centered on the thermistor to make it easier to capture hot air currents. Therefore, conventional heat detectors have a problem that even if the heat detector itself is not noticeable, the black thermistor stands out, and 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 the black thermistor depending on the viewing direction, resulting in poor visibility. Therefore, it is possible to form the protector from a transparent or translucent material, but this creates 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 that the protector stands out and does not blend in with the surrounding colors.

[0006] The present invention has been made in response to the above-mentioned problems, and its object 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 comprising a housing made of a cylindrical main body case with a bottom and an outer cover member covering the opening side of the main body case, a circuit board on which a thermistor and components constituting a detection circuit are mounted, the outer cover member having an opening formed at a position corresponding to the thermistor, an inlet through which outside air can flow in, forming a space facing the tip of the thermistor, and a protector section covering the opening, The surface of the thermistor is colored to easily reflect the color of the indicator light, an operation indicator light capable of emitting light from a portion 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 located within the insertion hole and corresponds to the opening of the outer cover member; A portion of the light emitted from the inner cover is configured to be irradiated onto the surface of the thermistor.

[0008] With a 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 color of 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, brightening the thermistor and 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. According to this configuration, the surface of the heat sensing element, the surface of the outer cover member, and the surface of the protector portion are of the same color scheme, so that the thermistor does not stand out against the housing and the color blends in with the surrounding environment.

[0011] Preferably, the inner cover is formed in a cone shape or a flat plate shape expanding 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 preferable that a part of the front or back surface of the inner cover is provided with a coating of the same color as the surface of the outer cover member. With this configuration, the inner cover can be made less noticeable compared to the housing. Effect of the Invention

[0013] The heat detector according to the present invention has the advantage of being able to improve the visibility of the operation indicator lamp and to make components such as the thermistor and protector less noticeable in the installation environment. [Brief description of the drawings]

[0014] [Figure 1] 1A and 1B show an embodiment of a heat detector according to the present invention, in which FIG. [Diagram 2] 1A is a front sectional view showing a first modified example of the heat detector of the embodiment in FIG. 1, and FIG. [Diagram 3] FIG. 4 is a front cross-sectional view showing another embodiment of a heat detector according to the present invention. [Figure 4]11 shows 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. [Diagram 5] 13 shows yet another example of the inner cover, where (A) is a front cross-sectional view and (B) is a bottom view. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of a heat detector according to the present invention will be described with reference to the drawings. Fig. 1 shows an exposed type heat detector, and Fig. 1(A) shows a front cross-sectional view of the heat detector of the embodiment, and Fig. 1(B) shows a perspective view of the heat detector of the embodiment. In the embodiment shown in Fig. 1, a case will be described in which the exterior of the detector is white, since the ceiling or 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 a 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.

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

[0017] In addition, the heat detector 10 of this embodiment is equipped with a circuit board 14 accommodated in the accommodating 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 having an insertion hole through which the thermistor 15 can be inserted and arranged so that its upper end contacts 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 composed of a printed wiring board on whose upper and lower surfaces electronic components 20 such as resistors, capacitors, and ICs (semiconductor integrated circuits) that constitute an electronic circuit for fire detection are mounted, and approximately in the center of the circuit board 14, the tips of the lead terminals of thermistor 15 penetrate 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 from white resin, and the thermistor 15 used has a surface coated with white paint such as epoxy resin. In this embodiment, the color of 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 may be any color that sufficiently reflects red light and is visible. 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, the decorative cover 13, and the 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 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 is provided with a ring-shaped head portion 12B 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 mortar-shaped portion 16b is made of a light-transmitting material such as polycarbonate resin, and an LED (light-emitting diode) 17 for notifying 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 consisting of a recess is provided at a portion facing the LED 17 on the rear surface of the flange portion 16c of the inner cover 16.

[0021] A light guide portion 16e consisting of a recess is provided at a portion of the rear surface of the flange portion 16c of the inner cover 16 facing the LED 17. A light reflecting portion 16f is provided on the surface of the flange portion opposite the light guide portion 16e (the lower surface in the figure). The light reflecting portion 16f is configured as a recess (groove) having a V-shaped cross section when viewed from the side, and the light of the LED 17 entering from the light guide portion 16e is reflected by the light reflecting portion 16f and guided to the entire cone-shaped portion 16b of the inner cover 16, and the light is emitted from the cone-shaped portion 16b, so that it is possible to indicate that the sensor is in operation. The number of LEDs 17 is not limited to one, and may be two or more.

[0022] Furthermore, in the heat detector of this embodiment, light emitted from the funnel-shaped portion 16b and 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, thereby increasing the apparent area of ​​the light-emitting display and widening the visible direction. Specifically, when the thermistor 15 is a typical black color, part of the cone-shaped portion 16b of the inner cover 16 is hidden by the thermistor 15 and the light of the operation indicator that hits the thermistor 15 is absorbed, reducing the amount of light, but when the surface of the thermistor 15 is a color that easily reflects the light emitted by the indicator, such as white, the light emitted from the cone-shaped portion 16b hits the surface of the thermistor 15 and is reflected, preventing a reduction in the amount of light and making the light-emitting state easier to see. It is preferable that the surface of the thermistor 15 be given a matte finish (a process that causes diffuse 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 easier to see.

[0023] Furthermore, the heat detector of this embodiment employs a structure in which the inside of the cylindrical portion 16a of the inner cover 16 is filled with resin 19. This allows high-pressure air to enter the housing (the board storage space inside the main body case 11) from a hole formed in the ceiling surface through which wiring and the like passes, and the high-pressure air flows out from the gap between the cylindrical portion 16a of the inner cover 16 and the thermistor 15, creating a cylindrical airflow layer around the thermistor 15, preventing the airflow from blocking the inflow of hot air to the thermistor 15, or preventing water from adhering to the thermistor 15, which makes it easier for dust to accumulate and thus reducing the heat detection function. In addition, by using a white resin as the filling resin 19, the color of the inside of the cylindrical portion 16a (for example, the color of the 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] Also, instead of facing the LED 17 to the flange 16c of the inner cover 16, as shown in FIG. 2(B), a window (round window) for the operation indicator may be provided on the flat surface of the outer cover 12, and the head of the bullet-shaped LED 17 may be exposed from the window. By disposing the bullet-shaped LED 17 in this manner and setting the height of the thermistor 15 so that the white thermistor 15 is included in the optical path of the light emitted from the LED 17 and spread by the convex lens of the head, the light from the LED 17 can be reflected on the surface of the thermistor 15 to function as a part of the operation indicator. Note that instead of protruding the head of the bullet-shaped LED 17 from the flat surface of the outer cover 12, a flat or convex lens may be provided in the window for operation indication of the outer cover 12. When the window is flat, the spread angle of the light is small, but by providing a convex lens, the spread angle of the light can be increased, and the thermistor 15 can be reflected even if its height is low.

[0025] Also, a white resist or insulating paint may be applied to the surface of the circuit board 14 (the lower surface in FIG. 1), or white silk printing may be performed. Similarly, the surface 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 seen through the inner cover 16, and the color of the board surface may be seen through the opening of the outer cover 12, or the opening may look black. However, by coloring the surfaces of the circuit board 14 and mounted components 20 white, the opening of the outer cover 12 can be brightened, and the entire sensor can be seen as a uniform white color. In this case, as described later, a microstructure can be processed to guide the light from the LED to the light-transmitting material when an alarm is activated and diffuse it to the surroundings.

[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 will also be described as an example in which the outer cover 12 is formed from white resin, and the thermistor 15 mounted on the circuit board 14 has a surface coated with white paint such as epoxy resin. In addition, the inner cover 16 is formed from a light-transmitting material, and a cylindrical light-guiding section 16e that protrudes toward the circuit board 14 is formed on the flange 16c. A low-height 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 16c of the inner cover 16, reflected by the light-reflecting section 16f formed there, and guided to the entire funnel-shaped section 16b of the inner cover 16. Light is emitted from the funnel-shaped section 16b, making it possible to indicate that the sensor is activated.

[0028] Furthermore, the inner cover 16 is provided with three locking pieces 16d formed so as to protrude vertically upward from the cone-shaped portion 16b (FIG. 3 shows one of the three locking pieces 16d). A claw portion is formed at the tip of each locking piece 16d, and the inner cover 16 is joined to the circuit board 14 by engaging this claw portion with an engagement hole 14a formed in the circuit board 14. The number of locking pieces 16d is not necessarily three, and two may be sufficient. 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 the heat detection function of thermistor 15 from deteriorating. The filled resin may be white or another color, but if the color of the case is white, the resin is preferably white. Also, if the color of the surrounding environment, such as the ceiling, is a color other than white, a white paint may be applied to the surface of the filled resin. In that case, the color of the case should also be matched.

[0029] Also, a white resist or insulating paint may be applied to the surface of the circuit board 14 (the underside in FIG. 3), or white silk printing may be performed. 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 the mounted components may be seen 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 the mounted components white, the opening in the outer cover 12 can be brightened, and the entire sensor appears to be uniformly white.

[0030] Next, other configuration examples of the inner cover 16 described in the embodiment of Fig. 1 and Fig. 3 will be described with reference to Fig. 4 and Fig. 5. Among these, the inner cover 16 in Fig. 4 is formed by applying a white paint to the surface of the mortar-shaped portion 16b except for the outer periphery to form a coating 18. Fig. 4(A) is a cross-sectional view of the inner cover 16, and Fig. 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 and spreads horizontally along flange portion 16c, and is configured to be 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 having a V-shaped cross section when viewed from the direction of arrow C in Fig. 4(B).

[0031] In a sensor to which this embodiment is applied, the light emitted from the annular portion spreads to the outside through the gaps in the pillars of the protector, and part of the light is irradiated and reflected by the surface of the white thermistor 15. This makes it easy to visually confirm the lighting state of the operation indicator light. The white coating 18 may be formed on the reverse side of the mortar-shaped portion 16b instead of on the front side, or a white film may be attached instead of applying paint. In this case, a white coating may also be formed on the surface of the resin 19 filled inside the cylindrical portion 16a of the inner cover 16 at the same time. The resin to be filled may be formed by two-color resin molding of white and opaque white, or two-color resin molding of white and transparent. The coating 18 is not limited to white, and may be any color based on white. Instead of forming the white coating 18, a structure capable of reflecting light guided inside (for example, a large number of fine grooves) may be formed. If a white coating is formed on the underside 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), the LED light will be emitted from the entire inside of the funnel-shaped portion, allowing sufficient light to be irradiated onto 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, exposing a part of the inside of flange 16c and allowing the light of the LED 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 be emitted from inner cover 16 to the surface of white thermistor 15 is increased, and the light of LED 17 can be reliably irradiated onto and reflected by the surface of white thermistor 15. As described above, the white coating on the front surface and the white coating on the back surface of the cone-shaped portion 16b may be formed at the same time. In this case, the area over which the light transmitted through the inner cover 16 made of a light-transmitting material is emitted to the outside from the inner cover 16 can be narrowed, and a sufficient amount of light can be obtained as an operation indicator lamp. 4(C), locking piece 16d for fastening inner cover 16 to circuit board 14 may be provided on flange portion 16c instead of on bowl-shaped portion 16b. In order to make it easier to collect light from LEDs 17, the end face of light-guiding portion 16e may be formed into a concave shape.

[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 periphery of the flange portion 16c. In addition, due to the provision of light exit portion 16g, light reflecting portion 16f formed on the surface of flange portion 16c corresponding to light guiding portion 16e is formed so as to form a V shape when cross-sectioned in the vertical direction so as to reflect light from light guiding portion 16e to the outside, i.e., light exit portion 16g, which differs from inner cover 16 of the embodiment in Figure 4.

[0034] The light output portion 16g has a ring shape as seen from below, as shown in Fig. 5(B). The light reflecting portion 16f is formed as a groove having a V-shaped cross section as seen from the direction of the arrow C in Fig. 5(B), similar to the embodiment in Fig. 4. Furthermore, in association with the provision of a rib-like 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 a plan view corresponding to the light-emitting portion 16g.

[0035] As shown in Fig. 5(A), the head of the light output section 16g is formed to have a shape that bulges downward, and the light is emitted from the light output section 16g while spreading due to the lens effect. A part of the light that is directed inward is irradiated and reflected by the thermistor 15, which has a white surface disposed on the inner side of the inner cover 16. Note that the position of the light output section 16g of the inner cover 16 in Fig. 5 is located outside the columnar partition wall 12C that constitutes the protector section, but it may be formed so that it overlaps with the partition wall 12C or is located inside. Instead of bulging, the head of the light output section 16g may be made flat.

[0036] In the 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 surface of a building, the entire cone-shaped 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 between the multiple partition walls 12C, i.e., 360°, 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. Also, 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 features: the thermistor 15 and outer cover 12 (including decorative cover 13) are similar in color; an emission color different from that of the thermistor 15 and outer cover 12 is emitted from LED 15; the emission color of LED 17 is guided by inner cover 16 or protector (12B, 12C) and thermistor 15; and a thermistor is provided that is similar in color to the outer cover and that easily reflects the emission color of the LED.

[0038] Although the present invention has been described above based on the embodiment, the present invention is not limited to the above embodiment. For example, in the above embodiment, the inner cover 16 is made of a light-transmitting material, and the light from the LED 17 is guided to the flange 16c of the inner cover 16 to emit light, but the protector part may be made separate 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 part via the partition wall 12C arranged directly above the LED 17 to emit light.

[0039] In this case, if the protector is made of a transparent material, it will look different from the white outer cover 12, so it is preferable to make the protector out of a translucent material that is a cloudy color of the same color as the color of the case, with fine particles of the same color (e.g., white) as the color of the case that diffusely reflect light being mixed into the material that forms the protector. This allows the protector to have a hue close to the color of the case when the LED 17 is turned off, and the entire detector can be unified in the same color, making the heat detector less noticeable when installed on the ceiling. Also, if the protector is made of a translucent material that has been structurally processed to be able to reflect light, the color of the case is transmitted as the background color when the light is not transmitted, and the light can be emitted in the emitting color when the light is transmitted, making the entire detector unified in the same color and making the heat detector less noticeable when installed on the ceiling. In addition, when the operation indicator light is turned on, the operation indication can be displayed in a highly visible form. 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 Cone-shaped part 16c Tsubabe 16d Locking piece 16e Light guide part 16f Reflective part 17 LED (Light emitting element) 18 Coating 19 Filling resin

Claims

1. A heat detector comprising a housing made of a cylindrical main body case with a bottom and an outer cover member covering the opening side of the main body case, a circuit board on which a thermistor and components constituting a detection circuit are mounted, and an opening is formed in the outer cover member at a position corresponding to the thermistor, and a protector part is provided to cover the opening, the protector part having an inlet through which outside air can flow in, forming a space facing the tip of the thermistor, The surface of the thermistor is colored to easily reflect the color of the indicator light, an operation indicator light capable of emitting light from a portion 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 located within the insertion hole and corresponds to the opening of the outer cover member; 2. A heat detector comprising: a heat detector configured such that a portion of the light emitted from the inner cover is irradiated onto a surface of the thermistor.

2. The surface of the thermistor is colored white or similar.

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 expanding from the insertion hole in a direction away from the circuit board.

4. 4. The heat detector according to claim 3, wherein a coating having a color similar to that of the surface of the outer cover member is provided on a part of the front or back surface of the inner cover member.

Images