JPH0516757B2 - - Google Patents

Description

[Detailed description of the invention]

(Technical Field) The present invention relates to an ultrasonic snow sensor. (Background technology) A snow sensor that uses ultrasonic waves transmits ultrasonic waves to the snow surface on the roof, receives the reflected waves, and
The snow height is measured from the time required from wave transmission to wave reception, and a detection operation is performed when the snow height exceeds a predetermined value. By the way, Fig. 9 shows the waveform of the signal involved in wave transmission, where a is the signal that determines the wave transmission timing and transmission time T _S , b is the signal supplied to the vibrator, and c is the signal that determines the wave transmission time T S. Although the signals appear at both ends, even after the signal is supplied to the vibrator during the transmission time T _S , the vibration continues to gradually attenuate due to reverberation during the reverberation time T _Z. However, since this type of ultrasonic snow sensor uses one vibrator for transmitting and receiving waves, reflected waves cannot be received during the transmitting time T _S and the reverberation time T _Z. Therefore, the area within a predetermined distance from the sensor section becomes a non-detection area. Conventional snow sensors (for example, Japanese Patent Application Laid-open No. 115975/1982) do not take the above-mentioned non-detection area into account, and when there is a lot of snow and the area reaches the non-detection area, they do not detect the snow accumulation even though they were originally intended. Although this is necessary, the drawback is that no snow detection signal is output. Note that in such a state, the snow is melting (normally, the snow melting device is activated by the snow detection signal from this type of snow sensor).
This occurs when the snow sensor exceeds its capacity, or when the snow sensor is turned on after the snow has accumulated. (Object of the Invention) The present invention has been proposed in view of the above points, and its purpose is to prevent snow accumulation that reaches the non-detection area (including cases where the sensor part is completely buried in snow). An object of the present invention is to provide an ultrasonic snow sensor capable of accurately detecting snowfall even in the event of snowfall. (Disclosure of the Invention) The present invention will be described in detail below with reference to the drawings showing embodiments. Fig. 1 is a block diagram showing an embodiment of the ultrasonic snow sensor of the present invention, Figs. 2 to 6 are time charts showing its operation, and Fig. 7 shows how it is installed in a house. It is a diagram. Hereinafter, the principle of operation of the present invention will be explained before explaining the embodiments. FIG. 8 is a diagram showing each detection area, where 1 is the sensor section and ROOF is the roof. Therefore, _LTH is a snow detection level, which indicates the snow level (snow height) at which a snow melting device or the like is desired to be turned on. Note that this setting is performed by the user operating a switch or the like (for example, selecting from three levels of setting values). Further, each region shown in the figure is as follows. Area: Area from the roof ROOF surface to snow detection level L _TH (length is x) Area: Area from snow detection level L _TH to the end of the non-detection area (length is L) Area: Non-detection area below the sensor unit 1 (length is l) Area: Non-detection area above the sensor unit 1 Therefore, the sensor unit 1 transmits ultrasonic waves to the roof ROOF, and the ultrasonic waves are reflected. It receives waves and detects the area from which the waves are reflected based on the time from transmission to reception, and has discovered that it is possible to classify the waves into modes as shown in the table below, depending on the state. Note that a case is shown in which the roof heater is operated based on the output of the snow sensor.

〔mode〕

This mode is the case where there is no reflected wave in both the area and the area. This indicates, for example, that the region or regions are covered with snow and that the reflected waves are completely hidden within the transmission time or reverberation time of the vibrator. Therefore, it may be determined that the snowfall is equal to or higher than the snowfall detection level _LTH , and the roof heater may be turned on. [Mode] This mode is a case where reflected waves exist only in a region. This means, for example, that a roof with zero snowfall
This occurs when there is a reflected wave from the ROOF, or when there is snow below the snow detection level _LTH .
Therefore, in this state, the snowfall is at the snowfall detection level L _TH
It may be determined that the following conditions are met and the roof heater may be turned off. [Mode] This mode is when reflected waves exist in the area. This is the case when there is snow in the area exceeding the set snow detection level _LTH , or when there is snow in the area and multiple reflections thereof appear in the area. Therefore, it may be determined that the snowfall is at or above the snowfall detection level _LTH , and the roof heater may be turned on. [Mode] This mode is when there are reflected waves in both the area and the area. This is a case where there is snow in the area exceeding the set snow detection level L _TH and multiple reflections of it are also appearing in the area. Therefore, it may be determined that the snowfall is at or above the snowfall detection level _LTH , and the roof heater may be turned on. By dividing into modes in this manner and sending snow detection signals according to each mode, a detection operation can be performed even when there is snow that reaches the non-detection area. Next, referring back to FIG. 1, an embodiment of the present invention will be described. In Fig. 1, 1 is a sensor unit that transmits and receives ultrasonic waves, 2 is a distribution board, and 3 is connected to the sensor unit 1 and distribution board 2 to detect snow accumulation and control snow melting operations. This is the detection circuit section. Note that H is a roof heater installed on the roof ROOF, and AC is a commercial power source. Fig. 7 shows an example of installation in a house, where 4 is a support for installing the sensor unit 1 at a predetermined position on the roof ROOF, 5 and 7 are wiring cords, and 6
is the detection circuit box. Returning to FIG. 1 and explaining the other configuration, the wave transmission circuit of the sensor unit 1 is connected to the wave transmission cycle setting circuit 11, the wave transmission width setting circuit 12, the reference oscillation circuit 13, and the wave transmission circuit 14 in the detection circuit unit 3. An intermittently generated ultrasonic signal is applied to the transmitter circuit 15, and the output of the wave transmitter circuit 15 drives a vibrator 16 provided in the sensor section 1. Further, the vibrator 16 is used for both transmitting and receiving purposes, and the signal generated at both ends of the vibrator passes through the receiving head amplifier 17 in the sensor section 1, and then passes through the receiving amplifier circuits 18, 19 in the detection circuit section 3.
AND gate AND ₁ through the integration circuit 20,
It is designed to be commonly applied to one input terminal of AND ₂ . On the other hand, the output of the transmission cycle setting circuit 11 includes a non-detection area gate setting circuit 21, a snow detection area gate setting circuit 22, and a snow detection area gate setting circuit 2.
4 are connected in sequence, and the other input terminal of the AND gate AND ₁ is connected to the snow detection area gate setting circuit 24.
The output of the snow detection area gate setting circuit 22 is given to the other input terminal of the AND gate AND ₂ .
The output is now given. The snow detection area gate setting circuit 22 includes a plurality of snow detection area gate setting circuits 22-1 to 22-n provided in parallel, and snow detection is performed by operating the snow detection level setting switch 23 in the distribution board 2. Any one of the area gate setting circuits 22-1 to 22-n
are now selected. Next, the output terminals of the AND gates AND ₁ and AND ₂ are connected to one input terminal of the flip-flops _{FF 1 and} FF ₂ , respectively _.
The output of the transmission cycle setting circuit 11 is commonly given to the other input terminal of the flip-flops FF ₁ ,
The output of FF ₂ is provided to a snow detection/judgment circuit 25. Next, the output of the snow detection and determination circuit 25 is sent to an output circuit 26, and the output of this output circuit 26 is provided to a roof heater control section 27 in the distribution board 2. Note that the roof heater control section 2
7 receives a signal indicating snowfall (snowfall detection signal) from the output circuit 26 and connects the commercial power AC to the roof heater H.
performs the operation of supplying the Further, 28 is a power supply circuit for supplying DC power to each part in the detection circuit section 3. The operation will be explained below according to the time charts shown in FIGS. 2 to 6. Note that each signal is
In the figure, waveforms at points with the same reference numerals are shown. First, FIG. 2 shows the relationship between the timing of wave transmission and the signals of the non-detection area gate setting circuit 21, the snow detection area gate setting circuit 22, and the snow detection area gate setting circuit 24. That is, the non-detection area gate setting circuit 21 generates a signal G 1 having a width of T ₁ from the rising edge of the output of the transmission cycle setting circuit 11 , and the snow detection area gate setting circuit 22 generates a signal G ₁ having a width of T 1 from the rise of the output of the transmission cycle setting circuit 11 . from the fall of
A signal G ₂₁ -G _2o with a width of T ₂₁ -T _2o is generated. Further, the snow detection area gate setting circuit 24 receives the output signal G ₂₁ of the snow detection area gate setting circuit 22.
From the falling edge of the selected one of G _2o to T ₃₁ ~
Signals G ₃₁ to _{G 3o} with a width of T _3o are generated. In addition, the width of the output signal _G1 of the non-detection area gate setting circuit 21
T ₁ corresponds to the distance l of the area in FIG.
Output signal of snow detection area gate setting circuit 22
The width T ₂ (T ₂₁ - _{T 2o} ) of G ₂ (G ₂₁ - _{G 2o} ) corresponds to the distance L of the area, and the snow detection area gate setting circuit 2
Width T ₃ (T ₃₁ - T _3o ) of output signal G ₃ (G ₃₁ - G _3o ) of 4
corresponds to the region distance x. Next, FIGS. 3 to 6 show the operations in the above-mentioned modes, respectively. The transmission cycle setting circuit 11 sends out the signal _S1 at a predetermined transmission cycle, and the transmission width setting circuit 12 processes the signal _S2 into a signal _S2 having a predetermined transmission width T.sub.S. Next, the reference oscillation circuit 13 generates a signal (ultrasonic signal) _S3 of frequency f during the period when the high-level signal is given from the transmission width setting circuit 12, and the signal is adjusted to a predetermined level by the transmission circuits 14 and 15. It is amplified and given to the vibrator 16. Note that the signal S ₅ on the output side of the wave transmitting circuit 15 has reverberation as shown in a, and if there is reflection, a reflected wave b appears. Further, the signal _S5 appearing at both ends of the vibrator 16 is amplified to a predetermined level via the receiving head amplifier 17 and the receiving amplifier circuits 18 and 19, and is converted into a signal having a rectangular envelope like the signal _R3 . Ru. Then,
This signal R ₃ is converted into a signal that slowly rises by removing high frequency components like the signal R ₄ by the integrating circuit 20, and is applied to one input terminal of the AND gates AND ₁ and AND ₂ . Note that by providing the integrating circuit 20 in this manner, malfunctions due to noise can be prevented. Therefore, in the AND gate _AND1 , the output signal of the integrating circuit ₂₀ is
When R ₄ goes high, the ANDed signal goes high, indicating that there is a reflection from the area. Furthermore, in the AND gate AND _2, if the output signal R ₄ of the integrating circuit 20 is at a high level during the period when the output signal G ₂ of the snow detection area gate setting circuit 22 is at a high level, the ANDed signal is It becomes high level, indicating that there is a reflection from the area. Note that since these signals can only be obtained for a short period of time, they are held by flip-flops FF ₁ and FF ₂ and output as signals P ₁₁ and P ₁₂ . Next, the snow detection/judgment circuit 25 performs the logical operations shown in the above table as turning on/off the roof heater, and sends out a snow detection signal. As a result, the roof heater control section 27 of the distribution board 2 operates via the output circuit 26, and the roof heater H is connected to the commercial power AC.
The snow melting operation is performed by supplying more power. (Effects of the Invention) As described above, in order to achieve the above object, the present invention measures the snow height using ultrasonic waves, and when the snow height exceeds a predetermined value, In an ultrasonic snow sensor that performs detection operation, the area between the sensor unit that sends and receives ultrasonic waves and the roof surface is the area from the roof surface to the snow detection level at which you want to turn on the snow melting device, etc., and this snow detection level. The area is divided into the area from to the end of the non-detection area, and the area from the end of the non-detection area to the sensor section, and the presence or absence of reflected waves from each area is determined, including multiple reflections, until the non-detection area is reached. (a) Even if the amount of snowfall exceeds the snow melting capacity of the roof heater and the snowfall exceeds the non-detection range of the ultrasonic snow sensor, the presence or absence of snowfall can be reliably detected. It can be detected and the roof heater can be activated. (b) Even if a user turns off the power to the ultrasonic snow sensor or roof heater, goes on a trip, etc., it snows heavily, and then turns on the power to the ultrasonic snow sensor or roof heater after returning home. It can be made to work. (c) Snowfall can be detected even if the sensor section is completely buried in snow, so there is no need to raise the height of the support to which the sensor section is attached. There are other effects.

[Brief explanation of drawings]

FIG. 1 is a block configuration diagram showing an embodiment of the ultrasonic snow sensor of the present invention, FIGS. 2 to 6 are time charts showing its operation, and FIG. 7 is a diagram showing how it is installed in a house. FIG. 8 is an explanatory diagram of the detection area, and FIG. 9 is an explanatory diagram of wave transmission and reverberation of the vibrator. 1... Sensor section, 2... Distribution board, 3... Detection circuit section, 4... Support column, 5, 7... Wiring cord, 6...
...Detection circuit box, H...Roof heater.

Claims (1)

[Claims] 1. A sensor unit that transmits and receives ultrasonic waves in an ultrasonic snow sensor that measures snow height using ultrasonic waves and performs a detection operation when the snow height exceeds a predetermined value. and the roof surface, the area from the roof surface to the snow detection level at which you want to turn on the snow melting device, etc.
The area is divided into an area from this snow detection level to the end of the non-detection area, and an area from the end of this non-detection area to the sensor section, and the presence or absence of reflected waves from each area is determined, including multiple reflections, and the An ultrasonic snow sensor characterized by being able to detect snow that reaches a detection area. 2. The ultrasonic snow sensor according to claim 1, which detects snowfall exceeding a snowfall detection level by performing a logical operation on the presence or absence of reflected waves from two areas: the above-mentioned area and the above-mentioned area.