JPH09102086A - Photoelectric sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the reliability of equipment and lower the cost by providing a heating body which indirectly heats a part related to an optical system for an optical signal. SOLUTION: When the power source is turned on, a heater 9 heats up and its heat is conducted to the optical system 6 through a housing 1 to indirectly warm its peripheral components such as a lens and a front plate of the optical system. The air above the heater 9 is heated and the lens and front plate of the optical system 6 are warmed indirectly by the convection of the air. Consequently, the temperature of at least the lens, front plate, etc., does not become lower than the ambient temperature to prevent the lens, front plate, etc., from getting fogged or drops of water from sticking on them. The antifogging effect and dew condensation prevention effect last as long as the power source is on. The components of the optical system are warmed indirectly, so the transmission of infrared rays as optical signals sent and received between a backlight part and a photo-detection part is not spoiled and no influence is exerted on the functions of the optical system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photoelectric sensor, and in particular, for example, a light-transmitting section and a light-receiving section are separately arranged, and a change in smoke or the like is detected by the light-receiving section by infrared rays projected from the light-transmitting section. The present invention relates to a photoelectric separated sensor.

[0002]

2. Description of the Related Art In a conventional photoelectric separation type sensor, an anti-fog filter is attached to each of the Fresnel lens and the front plate in order to prevent dew condensation on the Fresnel lens and the front plate. In addition, it is also proposed that a transparent heating element is directly attached to a lens filter to form an anti-fog heater (Actual fair 6-4).
(See Japanese Patent No. 1158).

[0003]

However, in the case of the conventional photoelectric sensor in which the anti-fog filter is attached to each of the Fresnel lens and the front plate, the effect of the anti-fog filter varies depending on the place of installation and its life is affected. received,
In particular, when it is installed in a place with a high humidity or a place with a large temperature difference, it needs to be replaced regularly, which makes maintenance difficult. Also, in the case of a conventional photoelectric sensor in which a transparent heating element is directly attached to the lens filter to form an anti-fog heater, the cost is high, and depending on how the heater is attached, the infrared transmissivity of the lens filter is high. However, there is a problem in that it affects the function of the optical system.

The present invention has been made in order to solve such a problem, and even when it is installed in a bad environment such as a place with high humidity or a place with a large temperature difference, it does not need to be replaced and can be used for a long period of time. It is an object of the present invention to obtain an inexpensive photoelectric sensor that operates accurately and is not affected by the function of the optical system due to heating or the like.

[0005]

SUMMARY OF THE INVENTION A photoelectric sensor according to the present invention is a photoelectric sensor which converts fire information into an optical signal and detects the signal, at least a portion of the optical signal relating to an optical system indirectly. It is provided with a heating element for heating.

Further, the photoelectric type is provided with a light transmitting section for generating an optical signal and a light receiving section which is separated from the light transmitting section and detects a change in smoke or the like based on the optical signal from the light transmitting section. In the sensor, the housing of the sensor is provided with a heating element that indirectly heats at least a portion related to the optical system of the optical signal. Moreover, the temperature control means connected to the heating element is provided.

Further, the portion related to the optical system is at least the lens of the optical system and the front plate of the cover of the housing. Further, the temperature control means is a temperature fuse that shuts off the power source of the heating element when the temperature of the resin forming the sensor reaches a predetermined temperature, or the temperature control means detects the temperature of the resin forming the sensor. And a control means for controlling the power supply of the heating element based on the output of the temperature detecting element.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a top view showing an embodiment of the present invention, and FIG. 2 is a side view showing a part of line AA in FIG. In the figure, 1 is a housing made of heat conductive material such as metal or resin, 2 is a cover of this housing 1, 3
Is a front plate of the cover 2, 4 is a rotary plate provided in the housing 1, 5 is a metal optical system support mounted on the rotary plate 4, and 6 is mounted on the optical system support 5. The optical system 7 is an elongated hole for adjusting the position angle of the optical system formed in the rotary plate 4.

Reference numeral 8 is an optical system lens, 9 is a heater provided as a heating element for indirectly heating the front plate 3, the lens 8 and the like, which is provided below the optical system support 5 in the housing 1.
Reference numeral 10 is a heater support plate that supports the heater 9, 11 is a screw for fixing the heater support plate, 12 is a printed circuit board provided in the housing 1, 13 is a connector attached to the printed circuit board 12, and 14 is a connector at one end thereof. Connected to 13,
The other end is a lead wire connected to a terminal block 15 provided behind the housing 1.

The entire structure of FIGS. 1 and 2 is substantially the same in the light transmitting section and the light receiving section in the photoelectric separation type sensor, and the difference between them is that the light emitting element and the light receiving element (not shown). No.) is different, in the case of the light receiving part for the light transmitting part, two printed circuit boards are required due to the signal processing amount, and for the light receiving part for the light transmitting part, the terminals of the terminal block are The number will increase. Of course, the number of this printed circuit board can be set to an arbitrary number, and FIG. 1 and FIG. 2 show the case of one printed circuit board 12, that is, the light transmitting unit, and another one is required. In the case of the light receiving part, it will be attached underneath.

FIG. 3 is an enlarged view of the portion of the heater 9. FIG. 3 (a) is a top view thereof, FIG. 3 (b) is a side view thereof, and FIG. 3 (c) is a longitudinal sectional view thereof. . In the figure, 1
6 is a fixing screw hole provided on each wing of the heater supporting plate 10, 17 is a heat-resistant adhesive for fixing the heater 9 to the heater supporting plate 10, and 18 is a lead wire 14 to the heater 9. It is a lead wire mounting portion for.

Next, the operation will be described. Now, when the power is turned on, the heater 9 is heated, and the heat is applied to the housing 1
To the optical system 6 through which the peripheral components such as the optical system lens 8 and the front plate 3 are indirectly warmed. Further, the air on the heater 9 is heated and the convection thereof also indirectly warms the lens 8 of the optical system, the front plate 3, and the like. As a result, at least the lens 8
The temperature of the front plate 3 and the like will not become lower than the ambient temperature, and the lens 8 and the front plate 3 will become cloudy.
Alternatively, water drops will not adhere to them. The anti-fog effect and the dew condensation prevention effect last as long as the power is turned on. Also, to indirectly heat the optical system parts,
It does not impair the transparency of infrared rays as an optical signal transmitted and received by the light transmitting section and the light receiving section, and does not affect the function of the optical system.

As an example, FIG. 4 shows a constant humidity (about 90%).
Shows the difference in the extinction rate depending on whether the heater 9 is turned on or off when the ambient temperature is changed from 15 ° C. to 45 ° C. over about 60 minutes. This extinction rate depends on the type of sensor. However, it is said that it is preferable to suppress it within 20%.
In FIG. 4, when the heater 9 is off, that is, when the power is not turned on, the extinction ratio exceeds 20% after about 15 minutes have elapsed from the start of temperature rise, and at this point, the lens of the optical system is 8 or the front plate 3 or the like may cause dew condensation to increase the light reduction rate too much, resulting in a fire alarm and a false alarm (non-fire alarm). However, when the heater 9 is turned on, that is, when the power is turned on, the extinction rate becomes about 10% after about 25 minutes from the start of the temperature rise, but the extinction rate does not increase any more, and the false alarm occurs. There is no possibility of causing such problems.

As an example, FIG. 5 shows a constant humidity (about 90%).
3 shows the temperature changes of the lens 8 of the optical system and the surface of the front plate 3 when the heater 9 is turned on and off when the ambient temperature is changed from 15 ° C. to 45 ° C. over about 60 minutes. In the figure, the relative temperature represents the difference in temperature between the surface of the lens 8 or the front plate 3 of the optical system with respect to the ambient temperature. For example, the relative temperature of 0 means that the lens 8 of the optical system or the front plate 3 of the ambient temperature. 3 indicates that the temperatures of the surfaces are equal.

In FIG. 5, the temperature of the lens 8 of the optical system and the front plate 3 may be lower than the ambient temperature by about 2 to 5 ° C. when the heater 9 is off, and dew condensation may occur, but when the heater 9 is on. It becomes higher than the ambient temperature by about 0 to 5 ° C. That is, when the heater 9 is turned on and off, the temperature becomes higher than the ambient temperature by about 5 ° C. on the surface of the lens 8 of the optical system and about 2 ° C. on the surface of the front plate 3. Therefore, dew condensation does not occur on the surface of the lens 8 and the surface of the front plate 3 of the optical system.
The temperature around the heater 9 when the heater 9 is turned on is about 20 ° C. higher than the ambient temperature, but since the limit temperature of use of the resin forming the sensor is about 90 ° C., the maximum operating temperature of the sensor is Even at 50 ° C, it stopped at 70 ° C, and there was no problem with the operating temperature.

As described above, in this embodiment, the lens 8 of the optical system and the front plate 3 which are the parts related to the optical system.
A heater 9 which is a heating element is provided in the housing near the optical system lens 8 and the like to indirectly heat the lens 8 of the optical system, the front plate 3 and the like, so that dew condensation is prevented and the lens 8 of the optical system and the front surface are prevented. The surface of the plate 3 and the like will not be fogged or water droplets will adhere. Further, since the lens 8 of the optical system, the front plate 3 and the like, which are parts related to the optical system, are indirectly warmed, the transparency of infrared rays as an optical signal interposed between the transmitting and receiving parts is not impaired, and the optical system It does not affect the function.

FIG. 6 is a top view showing an essential part of another embodiment of the present invention. In the figure, parts corresponding to those in FIG. 3 are denoted by the same reference numerals, and detailed description thereof will be omitted. Reference numeral 19 is a temperature fuse inserted in the middle of the lead wire 14 as a temperature control means and having a predetermined temperature, for example, 80 ° C. And
In the present embodiment, when the heater 9 indirectly heats the lens 8 of the optical system, the front plate 3 and the like, the heat of the heater 9 melts, for example, the optical system support 5 made of resin that constitutes the sensor. When there is a fear, the temperature fuse 19 positively shuts off the power source of the heater 9.

This will be further described with reference to FIG. FIG. 7 shows the temperature of each part of the sensor which changes with the passage of time starting from a constant ambient temperature, for example, 52 ° C. Here, it can be seen that the temperature rise of the lens 8 and the front plate 3 is not so large with respect to the temperature rise of the heater 9, but the temperature rise of the optical system support base 5 and the terminal base 15 is large. This is because the heater 9 is arranged below these components. Note that FIG. 7 shows two printed circuit boards, that is, the case of the light receiving portion, and a case where a large printed circuit board is mounted closer to the heater 9 than a small printed circuit board.

Here, for example, if the optical system support 5 is made of resin having a heat deformation temperature of 80 ° C. (in the case of 18.5 kg / cm ² ), the temperature of the optical system support 5 will be the heat deformation temperature. When it exceeds the limit, the optical system support 5 is deformed, and the focus of an optical element or lens (not shown) inside is deviated, so that normal monitoring may not be performed thereafter. Therefore, in such a case, the above-mentioned thermal fuse 19 is used to fix the optical system support 5
When the temperature reaches 80 ° C., the heater 9 is turned off. As a result, melting of the resin forming the optical system support 5 can be prevented in advance, and normal monitoring can always be performed.

As described above, according to the present embodiment, the power source of the heater 9 is shut off when the temperature of the optical system support 5 made of resin forming the sensor and the like, which constitutes the sensor, reaches 80 ° C. by the temperature fuse 19. Therefore, it is possible to prevent melting of the optical system support 5 and the like, which are components of the sensor made of resin, and to always perform normal monitoring.

In the above embodiment, the case where the temperature fuse is used as the temperature control means has been described, but the present invention is not limited to this, and other means, for example, an optical system made of resin that constitutes the sensor. A temperature detection element such as a thermistor or a thermocouple for detecting the temperature of the support base 5 and an electric circuit as a control means for controlling the power supply of the heater 9 based on the output of the temperature detection element are combined to substantially change the temperature. It may be controlled automatically so that the temperature of the resin portion does not reach the melting temperature. Further, when the heat deformation temperature of the resin is lower than 80 ° C., of course, a thermal fuse may be used which shuts off the power to the heater 9 at a temperature lower than 80 ° C., or controls the thermistor or the like. do it,
The melting temperature may not be reached.

[0022]

As described above, according to the present invention, in the photoelectric sensor for converting fire information into an optical signal for detection,
Since a heating element that indirectly heats at least the part of the optical signal related to the optical system is provided, dew condensation on the part related to the optical system is prevented, and the lens or front plate of the optical system that is the part related to the optical system. It will not fog or drop water on the surface, and will indirectly heat the optical system lens, front plate, etc., which is the part related to the optical system, thus impairing the transmission of infrared light which is an optical signal. Therefore, there is an effect that the function of the optical system can be surely retained, and thus the reliability of the device can be improved and the cost can be reduced.

Further, the photoelectric type is provided with a light transmitting section for generating an optical signal and a light receiving section which is separated from the light transmitting section and detects a change in smoke or the like based on the optical signal from the light transmitting section. In the sensor, since the housing of this sensor is provided with a heating element that indirectly heats at least a portion related to the optical system of the optical signal,
Condensation is prevented on the parts related to the optical system, and it is possible to prevent fog and water droplets from adhering to the surfaces of the optical system, such as the lens and front plate, which are parts related to the optical system. Since the lens or front plate of a certain optical system is indirectly warmed, the transparency of infrared light, which is an optical signal, is not impaired, and the function of the optical system can be reliably retained, thus improving the reliability of the device. At the same time, the cost can be reduced, and it is particularly useful for a separation type photoelectric sensor.

Further, since the temperature control means for automatically shutting off or controlling the power source of the heating element when the melting temperature of the component made of resin constituting the sensor is connected to the heating element is reached, It is possible to prevent melting of the optical system support, etc., which is a component of the other sensor, to always perform normal monitoring, and to improve the reliability of the device.

[Brief description of the drawings]

FIG. 1 is a top view showing an embodiment of a photoelectric sensor according to the present invention.

FIG. 2 is a side view showing an embodiment of the photoelectric sensor according to the present invention with a part cut away.

FIG. 3 is a diagram showing a main part of an embodiment of a photoelectric sensor according to the present invention.

FIG. 4 is a diagram for explaining an embodiment of a photoelectric sensor according to the present invention.

FIG. 5 is a diagram for explaining an embodiment of a photoelectric sensor according to the present invention.

FIG. 6 is a top view showing a main part of another embodiment of the photoelectric sensor according to the present invention.

FIG. 7 is a diagram for explaining another embodiment of the photoelectric sensor according to the present invention.

[Explanation of symbols]

 1 Housing 2 Cover 3 Front Plate 5 Optical System Support 6 Optical System 8 Optical System Lens 9 Heater 10 Heater Support Plate 14 Lead Wire 19 Thermal Fuse

Claims (6)

[Claims] 1. A photoelectric sensor for converting fire information into an optical signal for detection, comprising a heating element for indirectly heating at least a portion of the optical signal related to an optical system. Type detector. 2. A photoelectric type device comprising a light transmitting section for generating an optical signal, and a light receiving section which is separated from the light transmitting section and detects a change in smoke or the like based on the optical signal from the light transmitting section. In the sensor, a photoelectric sensor characterized in that a housing of the sensor is provided with a heating element that indirectly heats at least a portion related to the optical system of the optical signal. 3. The photoelectric sensor according to claim 1, further comprising a temperature control means connected to the heating element. 4. The photoelectric sensor according to claim 1, wherein the portion related to the optical system is at least a lens of the optical system and a front plate of the cover of the housing. 5. The photoelectric sensor according to claim 3, wherein the temperature control means is a temperature fuse that shuts off the power source of the heating element when the temperature of the resin forming the sensor reaches a predetermined temperature. 6. The temperature control means comprises a temperature detection element for detecting the temperature of the resin forming the sensor, and control means for controlling the power supply of the heating element based on the output of the temperature detection element. The photoelectric sensor according to claim 3.