JPH085738A - Ultrasonic switch - Google Patents

Abstract

PURPOSE:To provide an ultrasonic switch which is simplified in circuit configuration by reducing the number of components and reduced in detecting area variation resulting from temperature changes. CONSTITUTION:Ultrasonic waves are intermittently transmitted from a piezoelectric transducer 5 at the transmitting interval decided by a timing generating section 1. A signal correcting section 3 switches the transmitting level in two stages of a large stage and small stage at every transmission of the ultrasonic waves. The transducer 5 outputs a receiving signal corresponding to the receiving level of ultrasonic waves upon receiving the ultrasonic waves and a discriminating section 7 compares the level of the receiving signal with a threshold. When one of receiving signals outputted against the ultrasonic waves in the two stages is larger than the threshold and the other is smaller than the threshold, an outputting section 8 outputs an 'ON' output.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention transmits an ultrasonic wave to a surveillance space intermittently and receives a reflected wave to the transmitted wave to detect the presence or absence of an object within a detection area set in the surveillance space. The present invention relates to an ultrasonic switch that generates a corresponding output.

[0002]

2. Description of the Related Art In general, an ultrasonic switch of this type intermittently transmits an ultrasonic wave to a monitoring space, and when a reflected wave from an object is received, it is based on a time interval from the transmitted wave to the received wave. It has a configuration for determining the presence or absence of an object in the surveillance space.
Specifically, for example, as shown in FIG. 7, the wave transmission means for intermittently transmitting ultrasonic waves is determined by the timing generation unit 1 that determines the transmission interval of ultrasonic waves and the timing generation unit 1. It is composed of an oscillating unit 2 that intermittently sends out a high-frequency signal at a transmission interval, a boosting unit 4 that boosts the high-frequency signal, and an ultrasonic transducer 5 that is driven by the output of the boosting unit 4 and sends out an ultrasonic wave. To be done. The ultrasonic transducer 5 is also used as a wave receiving means, and the received wave signal output from the ultrasonic transducer 5 along with the reception of the ultrasonic wave is an amplification unit which constitutes the wave receiving means together with the ultrasonic transducer 5. Amplified by 6. The received signal amplified by the amplification unit 6 is input to the determination unit 7a, and the timing generation unit 1
The gate signal generator 7b is synchronized with the transmission interval determined by
The presence / absence of a received signal during the receiving gate period created by is determined. That is, the receiving gate period is set to a constant time between the transmission of ultrasonic waves and the next transmission, and the detection region for detecting the presence or absence of an object can be determined by the receiving gate period. When the determination unit 7a obtains the reception signal within the reception gate period, the output unit 8 generates an ON output. That is, as the output unit 8, a configuration for generating a binary signal having a voltage depending on the presence or absence of an object, or a configuration for generating a non-voltage contact output using a contact such as a relay is adopted.

[0003]

In the above-described conventional configuration, the gate signal generating section 7b is required to determine the detection area, so that the number of constituent elements increases, and the gate signal generating section 7b has a timing for determining the transmission interval. Since it is necessary to synchronize with the generation unit 1, there is a problem that the circuit configuration becomes complicated. That is, since there are many constituent elements and the circuit configuration is complicated, it is difficult to reduce the cost and the miniaturization is also limited. Further, in the above configuration, the detection region is determined by time assuming that the sound velocity is constant. However, if the ambient temperature changes, the assumption that the sound velocity is constant is not established and the detection region changes.

An object of the present invention is to solve the above-mentioned problems, and has a smaller number of constituent elements and a simpler circuit structure than in the case where the detection area is determined by the receiving gate period, which results in cost reduction and small size. It is an object of the present invention to provide an ultrasonic switch that can be realized in a small size and has a small variation in the detection area due to a temperature change.

[0005]

According to a first aspect of the present invention, there is provided a transmitting means for intermittently and alternately transmitting two kinds of ultrasonic waves having different transmitting levels to a monitoring space, and an ultrasonic wave from the monitoring space. By comparing the magnitude relation between the wave receiving means for receiving the wave and the wave receiving level at the wave receiving means and a prescribed threshold value, the wave receiving level of only one of the reflected waves for the above two types of ultrasonic waves is higher than the threshold value. And a determination output means for generating an ON output.

According to a second aspect of the present invention, the transmission levels are different from each other.
Of the ultrasonic wave from the monitoring space, the wave receiving means for receiving the ultrasonic wave from the monitoring space, and the wave receiving level at the wave receiving means and the specified threshold value. Comparing the magnitude relations, a state in which an ON output is generated when the receiving level of only one of the reflected waves for the above two types of ultrasonic waves is larger than a threshold value, and the receiving level for the ultrasonic wave of the larger transmitted level Is provided with a determination output means capable of selecting a state in which an ON output is generated when is smaller than a threshold value.

According to a third aspect of the present invention, the transmission levels are different.
Of the ultrasonic wave from the monitoring space, the wave receiving means for receiving the ultrasonic wave from the monitoring space, and the wave receiving level at the wave receiving means and the specified threshold value. Comparing the magnitude relationships, a state in which an ON output is generated when the received level of only one of the reflected waves for the above two types of ultrasonic waves is greater than a threshold value, and the received level for the ultrasonic wave of the smaller transmitted level Is smaller than the threshold value, a determination output means is provided which can select a state in which an ON output is generated irrespective of the other.

According to a fourth aspect of the present invention, in the first to third aspects of the present invention, the transmitting means is provided with a transmitting level adjusting section capable of adjusting the transmitting levels of the two types of ultrasonic waves. Is characterized by. The invention of claim 5 relates to claim 1
The invention according to claim 3 is characterized in that the judgment output means is provided with a threshold value adjusting section for adjusting a threshold value with respect to the reception levels of the above-mentioned two kinds of ultrasonic waves.

[0009]

According to the structure of the invention of claim 1, two kinds of ultrasonic waves having different transmission levels are intermittently and alternately transmitted to the monitoring space, and the reception level and the threshold value of the reflected waves of the ultrasonic waves are set. Of the two types of ultrasonic waves, an ON output is generated when the wave receiving level of only one of the reflected waves for the above two types of ultrasonic waves is larger than a threshold value. For example, the detection area can be defined by the sound pressure level of the ultrasonic wave to be transmitted and the threshold value for the received wave level, and in comparison with the case of setting the detection area by the time from the transmission of the ultrasonic wave to the reception wave, The circuit structure is simplified and the cost can be reduced, and moreover, the detection area hardly changes due to the temperature change.

According to the configuration of the second aspect of the present invention, when the wave receiving level of only one of the reflected waves for the two types of ultrasonic waves is larger than the threshold value, the ON output is generated, and the transmission level is large. Since it is possible to select the state in which the ON output is generated when the reception level for the other ultrasonic wave is smaller than the threshold value, simply selecting one of the two states,
Two types of detection areas can be selected. In this case, it is possible to select a detection area having boundary lines at both ends and a detection area farther than this detection area.

According to the third aspect of the present invention, when only one of the reflected waves for the two types of ultrasonic waves has a received level higher than a threshold value, an ON output is generated, and a transmitted level is low. It is possible to select a state in which the ON output is generated irrespective of the other when the reception level for the other ultrasonic wave is smaller than the threshold value. Therefore, by simply selecting one of the two states, there are two types of detection areas. Can be selected. In this case, a detection area having boundaries on both ends,
It is possible to select a distant detection area including this detection area.

According to the structure of the invention of claim 4, since the transmission level adjusting section for adjusting the transmission levels of the two kinds of ultrasonic waves is provided, the transmission levels of the respective ultrasonic waves are adjusted respectively. By doing so, the detection area can be arbitrarily set. According to the configuration of the invention of claim 5, since the threshold value adjusting section for adjusting the threshold values for the two types of ultrasonic wave reception levels is provided, the width of the detection region is not changed by changing the threshold value. It is possible to move the detection area to the far distance side and the short distance side.

[0013]

【Example】

(Embodiment 1) This embodiment has a configuration shown in FIG. 1 and transmits ultrasonic waves intermittently to the monitoring space, receives ultrasonic waves from the monitoring space, and determines the reception level. ,
The presence or absence of an object in the detection area set in the monitoring space is detected. The transmitting means includes a timing generating section 1 for determining the ultrasonic wave transmission interval, an oscillating section 2 for intermittently outputting a high frequency signal at the transmitting interval determined by the timing generating section 1, and an output from the oscillating section 2. The high-frequency signal of two different levels is generated from the generated high-frequency signal, and the high-frequency signal output from the signal correction unit 3 and the signal correction unit 3 that alternately outputs the high-frequency signal of each level each time the high-frequency signal is generated. Booster 4 for boosting
And an ultrasonic transducer 5 that is driven by the output of the booster 4 and sends an ultrasonic wave to the monitoring space. The signal correction unit 3 uses, for example, one that can switch between a state in which the output of the oscillating unit 2 passes as it is and a state in which the output of the oscillating unit 2 is attenuated by an attenuator, and each time a high-frequency signal passes through. The respective states are alternately switched. Therefore, the ultrasonic transducer 5 alternately outputs two types of ultrasonic waves having different transmission levels for each ultrasonic wave transmission.

The ultrasonic transducer 5 is also used as a wave receiving means. When the ultrasonic transducer 5 receives an ultrasonic wave, it outputs a received wave signal, and an amplifying section which constitutes a wave receiving means together with the ultrasonic transducer 5. The received signal is input to 6 and the received signal is amplified and detected. The received signal output from the amplification unit 6 is input to the determination unit 7 that constitutes the determination output unit together with the output unit 8. The determination unit 7 defines a threshold value for the received signal, and FIG.
As shown in FIG. 2B, whether the received signal level (outlined) for a pair of ultrasonic waves (shaded areas) transmitted at different transmission levels is greater than the threshold value SL, or the received signal level is as shown in FIG. Is smaller than the threshold value SL, the output unit 8
2 to generate an off output, and when the reception level of only one of the pair of reception signals is higher than the threshold value SL as shown in FIG. 2C, the output section 8 generates an on output. Actually, the received signal for the ultrasonic wave with a high transmission level becomes larger than the threshold value, and the received signal for the ultrasonic wave with a small transmission level becomes smaller than the threshold value. Therefore, the receiving side knows the transmission level. So that an ON output is generated when the received signal with the higher transmission level is greater than the threshold and the received signal with the lower transmission level is less than the threshold. Is also possible. The output unit 8 generates an ON output and an OFF output by a binary signal having a voltage or a contact signal having no voltage, as in the conventional configuration.

The ultrasonic wave transmission interval determined by the timing generator 1 is set to be longer than the maximum time interval from ultrasonic wave transmission to reception in the monitoring space. Therefore,
The next ultrasonic wave is not transmitted before the reflected wave of the ultrasonic wave transmitted to the monitoring space is received, and the received signal is received even though the ultrasonic transducer 5 is also used for transmission and reception. And the transmitted signal can be separated.

In the above configuration, the boundary line of the detection area is determined by the relationship between the wave transmission level and the threshold value, and as shown in FIG. 3, the monitoring space D ( The farthest end of the monitoring space D may be set by defining the minimum level of the received signal in the amplification section 6. Defining the minimum level of the received signal also leads to prevention of malfunction due to noise) , The nearer boundary line of the detection area E is set as the distance at which the received signal for the ultrasonic wave with the smaller transmitted wave level matches the threshold SL, and the farer boundary line of the detection area E has the higher transmitted wave level. The received signal for the other ultrasonic wave is set as a distance that matches the threshold SL. Therefore, if an object is present in the detection area E, the level of the received signal is higher than the threshold SL for the ultrasonic wave with a high transmission level, and the threshold SL for the ultrasonic wave with a low transmission level. Will be smaller than. However, in this example, it is assumed that the reflectance of the object to be detected with respect to the ultrasonic waves is constant. This assumption is valid for a use purpose such as detecting whether or not a member of the same type has passed through a line in a factory one after another. In this way, if the reflectance of the object does not change, the detection area E hardly changes even if the ambient temperature changes.

(Embodiment 2) In this embodiment, as shown in FIG. 4, in addition to the structure of Embodiment 1, a wave transmission level adjusting section 9 is added to the wave transmitting means, and a threshold value adjusting section is provided in the judgment output means. It has a configuration in which 10 is added. The transmission level adjusting unit 9 transmits 2
It is possible to adjust the transmission levels of various types of ultrasonic waves, and if the voltage division by the resistors is used as the configuration for determining the level of the high frequency signal in the signal correction unit 3, then among the plurality of resistors It can be realized by a simple configuration such as a configuration for selecting the one to be connected from or a configuration using a variable resistor. The threshold adjustment unit 10 adjusts the threshold for the received signal, and if a comparator is used as the determination unit 7 and the received signal output from the amplification unit 6 and the threshold value are compared, It is easy to divide the reference voltage to obtain the threshold value, continuously adjust the division ratio of the reference voltage using a variable resistor, or switch multiple resistors to change the division ratio step by step. It is realized with a simple configuration.

In this embodiment, since the transmission level and the threshold value can be adjusted, the detection area can be easily adjusted according to the purpose. Especially, if the transmission level is adjusted, the detection area can be set arbitrarily within the monitoring space, and if the threshold is adjusted, the width of the detection area obtained by adjusting the transmission level is not changed. Only the distance to the sensing area can be adjusted within the surveillance space. Further, it is possible to deal with a change in reflectance of an object by adjusting a transmission level or a threshold value. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 3) In the present embodiment, as shown in FIG. 5, a received signal selection section 11 is added to the configuration of the second embodiment. It has a function of selecting whether to employ both or only one of a pair of received signals for two types of ultrasonic waves having different levels. For example, as the determination unit 7, the output becomes H level when the level of the received signal is smaller than the threshold value SL.
And a second comparator whose output becomes H level when the level of the received signal is higher than the threshold value SL, using a logical sum of both comparators in a 2-bit shift register that uses the received signal as a clock. If the input configuration is adopted, each bit of the shift register becomes H level when only one of two adjacent received signals exceeds the threshold value SL. Therefore, if the logical product of both bits of the shift register is calculated and the ON output is generated from the output unit 8 when the logical product is at the H level, both types of ultrasonic waves are adopted and the detection area is adopted. It means that E has been decided. Further, if the output unit 8 is controlled by using only the output of the first comparator, the above-described detection area E
If the output of the second comparator is controlled by controlling only the output of the second comparator and inverting the output, the detection area is set to be farther than the nearer boundary line of the detection area E. The detection area is located farther than the far boundary line.

In short, when both the received signals for the ultrasonic waves of the transmission level of two steps of high and low are adopted, it is the same as the second embodiment, and the boundary line of the detection area E is as shown in FIG. 6 (a). Will be set at both ends. When only one of them is adopted, the determination unit 7 determines that an object exists in the detection area E only when the received signal is smaller than the threshold value SL, and causes the output unit 8 to generate an ON output. To do. Therefore, the transmission level and the threshold SL are shown in FIG.
When the reception signal for the ultrasonic wave with the smaller transmission level is adopted in the same manner as in the case of (a), the detection area E is the detection area set in FIG. 6 (a) as shown in FIG. 6 (b). Including, it is set to the far side. Further, when the reception signal for the ultrasonic wave with the higher transmission level is adopted, the detection area E should be set farther than the detection area set in FIG. 6A, as shown in FIG. 6C. become.

As described above, in the configuration of this embodiment, the detection area can be easily selected from the three types of patterns by the received signal selection section 11 with the transmission level and the threshold SL fixed. . Other configurations and operations are similar to those of the second embodiment.

[0022]

According to the invention of claim 1, two kinds of ultrasonic waves having different transmission levels are intermittently and alternately transmitted to the monitoring space.
The magnitude relationship between the received wave level of the reflected wave of the ultrasonic wave and the threshold value is compared, and if the received wave level of only one of the reflected waves for the above two kinds of ultrasonic waves is larger than the threshold value, ON output is generated, If the reflectance of the object to the ultrasonic wave is constant, the detection area can be defined by the sound pressure level of the ultrasonic wave to be transmitted and the threshold value for the received wave level. Compared with the case where the detection area is set, the circuit configuration is simplified and the cost can be reduced, and moreover, there is an advantage that the detection area hardly changes due to temperature change.

According to a second aspect of the present invention, an ON output is generated when the wave receiving level of only one of the reflected waves for the two types of ultrasonic waves is larger than a threshold value, and the ultrasonic wave having the larger transmitting level. Since it is possible to select the state where ON output is generated when the received wave level for is smaller than the threshold,
By simply selecting one of the two states, it is possible to select a detection area having boundaries at both ends and a detection area farther than this detection area.

According to the third aspect of the present invention, when only one of the reflected waves for the two types of ultrasonic waves has a received wave level higher than a threshold value, an ON output is generated, and an ultrasonic wave with a lower transmitted level is used. Since it is possible to select a state in which an ON output is generated irrespective of the other when the received wave level with respect to is smaller than the threshold value, by simply selecting one of the two states, a detection area having a boundary line at both ends is obtained. The advantage is that the detection area on the far side including this detection area can be selected.

According to the fourth aspect of the present invention, since the transmission level adjusting section for adjusting the transmission levels of the two kinds of ultrasonic waves is provided, the detection is performed by adjusting the transmission levels of the respective ultrasonic waves. There is an advantage that the area can be set arbitrarily. According to the fifth aspect of the present invention, since the threshold value adjusting unit for adjusting the threshold values for the two types of ultrasonic wave reception levels is provided, the detection area can be extended without changing the width of the detection area by changing the threshold value. There is an advantage that it can be moved to the distance side and the short distance side.

[Brief description of drawings]

FIG. 1 is a block diagram of a first embodiment.

FIG. 2 is an operation explanatory diagram of the first embodiment.

FIG. 3 is an operation explanatory diagram showing a detection region according to the first embodiment.

FIG. 4 is a block diagram of a second embodiment.

FIG. 5 is a block diagram of a third embodiment.

FIG. 6 is an operation explanatory view showing a detection area of the third embodiment.

FIG. 7 is a block diagram of a conventional example.

[Explanation of symbols]

 1 Timing Generation Section 2 Oscillation Section 3 Signal Correction Section 4 Boosting Section 5 Ultrasonic Transducer 6 Amplification Section 7 Judgment Section 8 Output Section 9 Transmission Level Adjustment Section 10 Threshold Adjustment Section 11 Received Signal Selection Section

Claims (5)

[Claims] 1. A transmitting means for intermittently and alternately transmitting two types of ultrasonic waves having different transmitting levels to a monitoring space, a receiving means for receiving ultrasonic waves from the monitoring space, and a receiving means. And a determination output means for generating an ON output when the received wave level of only one of the reflected waves for the above two kinds of ultrasonic waves is larger than the threshold value. An ultrasonic switch characterized by being provided. 2. A transmitting means for intermittently and alternately transmitting two kinds of ultrasonic waves having different transmitting levels to a monitoring space, a receiving means for receiving ultrasonic waves from the monitoring space, and a receiving means. The magnitude relationship between the received wave level in the above and the specified threshold value is compared, and when the received wave level of only one of the reflected waves for the above two types of ultrasonic waves is higher than the threshold value, the ON output is generated and the transmitted wave is transmitted. An ultrasonic switch, comprising: a determination output unit capable of selecting a state in which an ON output is generated when a reception level for an ultrasonic wave having a higher level is smaller than a threshold value. 3. A transmitting means for intermittently and alternately transmitting two kinds of ultrasonic waves having different transmitting levels to the monitoring space, a receiving means for receiving the ultrasonic waves from the monitoring space, and a receiving means. The magnitude relationship between the received wave level in the above and the specified threshold value is compared, and when the received wave level of only one of the reflected waves for the above two types of ultrasonic waves is higher than the threshold value, the ON output is generated and the transmitted wave is transmitted. An ultrasonic switch, comprising: a determination output means capable of selecting a state in which an ON output is generated irrespective of the other, when a reception level for an ultrasonic wave having a smaller level is smaller than a threshold value. 4. The wave sending means is provided with a wave sending level adjusting section for adjusting the wave sending levels of the two types of ultrasonic waves, respectively. Ultrasonic switch described. 5. The determination output means is provided with a threshold value adjusting section for adjusting a threshold value with respect to the reception levels of the two types of ultrasonic waves, and the determination output means is provided with the threshold value adjusting section. Ultrasonic switch.