JPH0297101A - Thawing device for antenna - Google Patents

Abstract

PURPOSE:To efficiently prevent an antenna from being snowed over by supplying power to the heater of a moisture detector by a control circuit at the time of detecting a temperature where it may snow by a temperature detector and supplying power to a thawing heater at the time of detecting this temperature and moisture. CONSTITUTION:When the ambient temperature falls to <5 deg.C where it may snow, a detection signal DS2 in the high level is outputted from a second temperature detector 92. Then, a second power switch 85 is closed to supply power to a heating body 84 of a moisture detector 8. Therefore, a detection signal SS ia outputted from the detector 8 immediately when it begins to snow. When the ambient temperature falls to 0 to 3 deg.C or lower for snowing at this time, a detection signal DS1 in the high level is outputted from a first temperature detector 91. As the result, a first power switch 63 is closed to start power supply to heating bodies 5 and 6. That is, power supply to heating bodies 5 and 6 is started immediately when it begins to snow.

Description

Detailed Description of the Invention [Object of the Invention] (Industrial Application Field) The present invention is directed to a snow melting method for preventing snow from accumulating on the antenna, for example, in an antenna used in an earth station for satellite communication. Regarding equipment.

(Prior Art) In recent years, with the development of satellite communication technology and the start of satellite broadcasting services, a large number of earth stations have been installed. These earth stations generally use mirror antennas such as parabolic antennas and Cassegrain antennas that can provide large gains. However, due to the structure of this type of antenna, snow tends to accumulate on the main reflector and the horn-shaped feed section, and when snow accumulates, the direction of the main beam of the antenna shifts and signal attenuation increases, so it is especially difficult to avoid snow accumulation. When used in areas, it is necessary to install a snow melting device.

Therefore, in conventional large antennas used for public communications, for example, a snow melting heater is installed on the back side of the main reflector, and a worker manually energizes the heater depending on the weather conditions. This prevents snow from accumulating on the antenna. However, with such a snow melting device, there may be a significant delay in starting energization of the snow melting heater, or there may be unnecessary energization, so that snow melting cannot be performed efficiently.

On the other hand, devices have also been devised that detect snowfall and automatically energize a snow melting heater. However, this type of conventional device collects snow using a snow collector similar to a rainfall meter, recognizes snowfall by detecting the water that naturally melts from this snow, and then activates a snow melting heater. It is composed of Therefore, depending on the temperature, there is a drawback that it takes a long time from the start of snowfall until the snow melting heater is energized.

(Problems to be Solved by the Invention) As described above, conventional snow melting devices rely on manual operation by workers to energize the snow melting heater, or detect snowfall using a detector similar to a rainfall meter. However, since the snow melting heater is energized, there is a problem in that the snow melting heater cannot be properly energized, and as a result, the snow that has accumulated on the antenna cannot be efficiently melted.The present invention solves this problem. The present invention aims to provide a snow melting device for antennas that can detect snowfall reliably and quickly and accurately control the energization to the snow melting heater, thereby efficiently melting snow that has accumulated on the antenna. be.

[Structure of the Invention] (Means for Solving the Problems) The present invention includes a moisture detector equipped with a heater that detects when moisture has adhered to a detection surface, and a moisture detector that detects when the ambient temperature has reached the snowfall temperature. a second temperature detector that detects that the ambient temperature has reached a snowfall temperature higher than the snowfall temperature, and a control circuit, and the control circuit controls the second temperature. When the detector detects a snowfall temperature, the heater of the moisture detector is energized to heat the detection surface, and the first temperature detector detects the snowfall temperature, and the moisture detector detects moisture. The snow melting heater is energized when the snow is melting.

(Function) As a result, when the ambient temperature reaches a temperature that allows snow to fall, the heater of the moisture detector is energized and the detection surface is heated in advance. Snowfall is quickly detected at its onset, as it melts and is detected immediately upon contact with the detection surface. In addition, even if a detection signal is output from the moisture detector, the snow melting heater is not energized if the ambient temperature has not reached the snowfall temperature, so the heater is not energized in the case of rain and only in the case of snowfall. As a result, only snowfall can be detected reliably and electricity can be applied without waste.

That is, according to the present invention, it is possible to optimally control the energization of the snow melting heater, thereby efficiently preventing snow from accumulating on the antenna.

(Example) Fig. 2 shows the configuration of a parabolic antenna equipped with a snow melting device according to an example of the present invention. , and a feeding horn section 4 is disposed at a position facing the reflecting surface of the main reflecting mirror 2. Incidentally, reference numeral 3 denotes a support arm for fixing the power feeding horn portion 4 to the lower end portion of the main reflecting mirror 2.

Incidentally, a heating element 5 is disposed on the reflecting surface of the main reflecting mirror 2 of such a parabolic antenna, and a heating element 6 is further disposed on the circumferential surface of the cover of the power feeding horn section 4. As shown in FIG. 3, the heating element 5 is, for example, a surface heating element or a wire heating element, etc. after coating the reflective surface of the main reflecting mirror 2 with a paint 51 made of a polymeric material with low thermal conductivity. Body main body 5
0, and a thin film 52 made of a polymeric material having a small coefficient of friction is coated thereon.

It should be noted that the heating element 6 provided in the power feeding horn section 4 also has substantially the same configuration as the heating element 5 of the main reflecting mirror 2 described above.

These heating elements 5, 6 generate heat when energized by a power supply (not shown), and melt snow that has accumulated on the covers of the main reflector 2 and the power supply horn section 4. However, in the case of the power supply horn section 4, since a heating element cannot be provided at the horn opening, a snow-covered eave 7 made of a thin film of a polymeric material is provided at the horn opening.

On the other hand, a snow melting control unit 1 consisting of a moisture detector 8 and a temperature detector 9 is mounted on the stand 1 of the parabolic antenna.
0 is installed. First of all, the moisture detector 8 consists of a minute slit meander type line, and its structure is, for example, as shown in FIG. A meandering rectangular slit 83 is provided. A predetermined detection voltage is applied between the pair of conductor layers 82 electrically separated by the slit 83. Also,
A surface heating element 84 is disposed on the back side of the moisture detector 8 as described above with an adhesive material having high thermal conductivity interposed therebetween. This surface heating element 84 heats the moisture detector 8 to a temperature (5 to 10°C) sufficient to melt snow, and the heating element 84 provided on the main reflecting mirror 2 and the power supply horn section 4 , 6, it generates heat when it is energized from a power supply (not shown).

In addition, this moisture detector 8 is placed at a distance of, for example, 45 mm with respect to the stand 1.
It is installed at an angle of about 100 cm.

FIG. 1 shows the snow melting control unit 10 and the heating element 5,
6 shows the circuit configuration of the energizing circuit portion. The snow melting control unit 10 has first and second temperature detectors 91 and 92 as temperature detectors 9. These temperature detectors 91 and 92 are connected to a power source 97 as shown in FIG.
A thermistor 95 is connected through a variable resistor 94 to
The thermistor is made of, for example, BaTi03E oxide semiconductor ceramics doped with monovalent or trivalent impurities. Of these temperature detectors 91 and 92, the first temperature detector 91 outputs an "H" level ( For example, the characteristics of the thermistor 95 are set to output a detection signal DS of 5V). On the other hand, the second temperature detector 92 is a thermistor so as to output an "H" level detection signal DS when the ambient temperature falls below the snowfall temperature (approximately 5 degrees Celsius), which is slightly higher than the snowfall temperature. 95 characteristics are set. FIG. 6 shows an example of the characteristics of the thermistor 95 of this second temperature detector 92.

The detection signal DSL of the first temperature detector 91 among these temperature detectors 91 and 92 is AND-processed with the detection signal SS of the moisture detector 8 by an AND gate 93, and then outputted as the first switch control signal. The power is supplied to the energization switch 53. This first energization switch 53 is inserted into the energization path to the heating elements 5 and 6 provided in the main reflecting mirror 2 and the power feeding horn section 4, and a switch control signal is output from the AND gate 93. Conduction occurs when On the other hand, the detection signal DS output from the second temperature detector 92 is supplied as is to the second energization switch 85. This second energization switch 85 is connected to a heating element 8 provided in the moisture detector 8.
4, and becomes conductive when the detection signal DS2 is output from the second temperature detector 92.

Next, the operation of the apparatus configured as above will be explained.

First, when the ambient temperature is higher than the snowfall temperature (5 degrees Celsius), both the first and second temperature detectors 91 and 92 indicate "
H'' level detection signals DSI and DS2 are not output.

For this reason, both the first and second energizing switches 53.85 are in the open state, and therefore not only the main reflection fa2 and the heating elements 5 and 6 of the power supply horn section 4 but also the moisture detector 8 generate heat. The body 84 is also not energized.

Now, in this state, the ambient temperature drops to the temperature at which snowfall is possible (5 degrees Celsius).
), then the second temperature sensor 92 detects H
“The level detection signal DS2 is output, and this causes the second level detection signal DS2 to be output.
The energization switch 85 becomes conductive and the heating element 8 of the moisture detector 8
4, energization is performed. Therefore, the moisture detector 8 is heated by the heating element 84 and maintained at a temperature (3 to 5 degrees Celsius) sufficient to melt the snow. Therefore, if it snows in this state, even if the ambient temperature is low, the snow immediately melts into water droplets as soon as it falls onto the detection surface of the moisture detector 8. Therefore, the moisture detector 8 outputs the detection signal SS immediately after the snowfall starts. Further, at this time, if the ambient temperature has fallen below the snowfall temperature (0 to 3° C.), the first temperature detector 91 outputs the “H” level detection signal DSI. Therefore, the AND gate 93 is turned on when the detection signal SS is output from the moisture detector 8, and as a result, the energization switch 5 of node 1
3 becomes conductive, and electricity supply to the heating elements 5 and 6 is started. That is, as soon as snowfall begins, power supply to the heating element 5.6 starts.

Therefore, the main reflection vL2 and the feeding horn section 4 are reliably heated before snow accretion begins, and as a result, snow accretion on the antenna is prevented.

Note that the moisture detector 8 outputs the detection signal SS even in the case of rain instead of snowfall. However, in this case, since the ambient temperature is higher than the snowfall temperature (0 to 3 degrees Celsius), the first temperature detector 91 does not output the "H" level detection signal DSI, and therefore the AND gate 93 maintains the off state, and thereby the first energization switch 53 also maintains the open state.Therefore, the heating element 5.6 is not energized, and as a result, power is not wasted.

As described above, according to this embodiment, the following various effects can be obtained.

■ A heating element 84 is provided in the moisture detector 8, and this heating element 8
Since the moisture detector 8 is warmed in advance by energizing the moisture detector 4 when the temperature reaches a temperature that allows snowfall, it is possible to immediately detect snowfall even if the ambient temperature is low. can. Therefore, the heating elements 5 and 6 can be energized and driven quickly before snow builds up on the antenna, thereby making it possible to always prevent snow from accumulating on the antenna.

■ Also, the conditions for energizing the heating element 5.6 are such that the first temperature detector 91 detects that the ambient temperature has fallen below the snowfall temperature, and in this state, the moisture detector 8 detects moisture. Therefore, only snowfall can be detected accurately. Therefore, there is no need to worry about energizing the snow melting heating element 5.6 in the case of rain instead of snowfall, and as a result, snow accretion can be efficiently prevented without wasting power.

■ Since the moisture detector 8 is arranged in an inclined position rather than in a horizontal position, even if debris or dirt adheres to the detection surface of the moisture detector 8, it will be naturally washed away by water droplets from snowfall or rain. As a result, it is possible to reduce malfunctions of the moisture detector 8 and perform stable snowfall detection.

■ Since the heating element 5 is provided on the detection surface side rather than on the back side of the main reflector 2, snow accretion on the main reflector 2 can be melted directly rather than indirectly, which allows relatively low power consumption. You can reliably prevent snow from accumulating.

Note that the present invention is not limited to the above embodiments. For example, in the above embodiment, the heating element 84 of the moisture detector 8 is energized only when the ambient temperature has fallen below the snowfall temperature. It is also possible to energize the heating element 84 when the amount increases above the threshold value. In this way, the conditions for energizing the heating element 84 of the moisture detector 8 can be limited to weather conditions that are more likely to cause snowfall, thereby further reducing wasteful power consumption. Also,
The surrounding air temperature and the temperature of the object to be heated may be monitored during energization, and the current applied to each heating element 5, 6° 84 may be variably controlled depending on the temperature. This makes it possible to always perform the most efficient heating according to the weather conditions. In addition, the gist of the present invention is also described with respect to the configuration and arrangement position of the heating element, moisture detector, and temperature detector, the configuration of the control circuit, the detected temperatures of the first and second temperature detectors, the type of antenna, etc. Various modifications can be made without departing from the scope.

[Effects of the Invention] As detailed above, according to the present invention, there is provided a moisture detector equipped with a heater that detects that moisture has adhered to the detection surface, and a first moisture detector that detects that the ambient temperature has reached the snowfall temperature. a second temperature detector that detects that the ambient temperature has reached a snowfall temperature higher than the snowfall temperature, and a control circuit, and the control circuit controls the second temperature detection. When the snowfall temperature is detected by the sensor, the heater of the moisture detector is energized to heat the detection surface, and the first temperature detector detects the snowfall temperature and the moisture detector detects moisture. By energizing the snow melting heater when snow is falling, it is possible to detect snowfall reliably and quickly and accurately control the energization to the snow melting heater. This allows for efficient snow melting to prevent snow from accumulating on the antenna. A snow melting device for antennas that can be used can also be provided.

[Brief explanation of drawings]

The figures are for explaining a snow melting device for an antenna according to an embodiment of the present invention. FIG. 1 is a block diagram showing the circuit configuration of the snow melting control unit and the energizing circuit portion of the device, and FIG. 2 is a side view of the antenna. Figure 3 is a partial cross-sectional view of the main reflector, Figure 4 is a perspective view showing the configuration of the moisture detector, Figure 5 is a circuit diagram of the temperature detector, and Figure 6 is the temperature detector used. It is a figure showing an example of the characteristic of the thermistor. 1...Stand, 2...Main reflector, 3...Support arm, 4...Power supply horn part, 5, 6...Heating element for snow melting, 7...For snowy roads Eaves, 8... Moisture detector, 9
... Temperature detector, 10 ... Snow melting control unit, 50
...Heating element body, 51...Paint, 52...Thin film,
53... First energization switch, 81... Dielectric substrate, 82... Conductor layer, 83... Slit, 84...
- Heating element for moisture detector, 85... Second energization switch, 91... First temperature detector, 92... Second temperature detector, 93... AND gate, 94...・Variable resistor, 95...Thermistor, 96...Zena diode. Applicant's representative Patent attorney Takehiko Suzue Figure Figure Figure Figure Boiling [°C] Figure

Claims (1)

[Claims] In snow melting equipment for antennas, a snow melting heater is installed in the snow accumulating part of the antenna, and when it snows, the snow melting heater is energized to melt the snow. a detector, a first temperature detector that detects that the ambient temperature has reached a snowfall temperature, and a second temperature detector that detects that the ambient temperature has reached a snowfall temperature higher than the snowfall temperature. When the temperature at which snowfall is possible is detected by the second temperature detector, the heater of the moisture detector is energized to heat the detection surface, and when the snowfall temperature is detected by the first temperature detector and the moisture A snow melting device for an antenna, comprising a control circuit that energizes the snow melting heater when moisture is detected by a detector.