JPS62115327A - Multifunctional sensor device - Google Patents

Abstract

PURPOSE:To detect information from plural information sources by a single sensor by inflecting a thin film where a semiconductor strain sensor is stuck according to external pressure. CONSTITUTION:A silicon substrate 4 is fitted and fixed on a discoid fitting base 1 across a spacer 3 and a couple of semiconductor strain sensors 6a and 6b are arranged at specific positions on the top surface of the thick part 5 of the substrate. A cylindrical case 8 is fitted around the base body 1 and a mesh-shaped cover 9 is fitted on the top surface side of the case. When the thin film 5 is applied with pressure externally, the thin film 5 flexes corresponding to the external pressure and the sensors 6 and 6b stuck thereupon expand or contract according to the quantity of inflection to vary in resistance value. The variation is detected to know the value of the pressure applied to a sensor 10. Then, the sensor 10 is usable as a pickup device for vibration detection and also as a normal microphone and a temperature sensor.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention uses semiconductors to detect vibrations emitted from various manufacturing equipment installed in a factory, sounds in the factory, and even the temperature of equipment during use. The present invention relates to a multifunctional sensor device capable of detecting with a sensor.

[Prior art] For example, when measuring vibrations emitted from industrial manufacturing equipment installed in a factory, vibrations in special frequency ranges, and even the temperature of the manufacturing equipment, it is generally necessary to Sensors are often used depending on the measurement purpose.

Condenser microphones are used to detect vibrations emitted by manufacturing equipment, vibrations in special frequency ranges, and to collect sounds such as conversations of on-site employees. A condenser microphone with different frequency characteristics is used.

Similarly, temperature sensors are used to measure the temperature of manufacturing equipment during operation.

[Problems to be Solved by the Invention] As described above, conventionally, sensors are individually arranged according to the purpose of detection to pick up the necessary information.

Therefore, when there are many information sources, it is necessary to install as many sensors as there are information sources, and managing them is also difficult.

In addition, when using a condenser microphone like the one mentioned above as a sensor in such a place, dust generated in the factory or oil splashed from manufacturing equipment may stick to the condenser microphone. This causes the characteristics of the microphone to deteriorate and the life of the microphone to be significantly shortened.

Therefore, in this invention, the upper sensor is capable of detecting information from the multiple information sources mentioned above, and the upper sensor is equipped with a multi-sensor that does not affect the detection characteristics even if dust or oil adheres to it. It provides:

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention skillfully utilizes the characteristics of a semiconductor strain sensor, which will be described later.
A sensor device is configured.

That is, in the multi-machine sensor device according to the present invention, a pair of semiconductor strain sensors are respectively arranged at predetermined positions on a thin film, and the amount of strain of the semiconductor strain sensor changes in response to the deflection of the thin film due to external pressure. At the same time, these pair of semiconductor strain sensors are connected in a bridge, and a sensor output corresponding to the amount of strain of the semiconductor strain sensor is obtained from the two output terminals of the bridge circuit, and this sensor output is connected to a sensor amplifier. The ambient temperature at the location where the semiconductor strain sensor is placed can be detected from voltage fluctuations occurring in a circuit system including the semiconductor strain sensor.

[Operation] If a semiconductor strain sensor is attached to a predetermined position on a thin film and this thin film is deflected in response to external pressure, the amount of strain on the semiconductor strain sensor will change accordingly. can be used as a pressure sensor at 41 tlA, and this sensor is resistant to dust and oil, so even if these particles adhere to a semiconductor strain sensor or thin film, its detectability will hardly be affected.

Furthermore, this multi-Itffi sensor can obtain a sensor output proportional to the external pressure applied to it, so it can detect anything from minute vibrations to vibrations in the acoustic range or beyond, with a dynamic range of about 8 digits. By appropriately performing subsequent filter processing, it is possible to separate the necessary information from the information in the high frequency range and detect it from a single sensor.

Since semiconductor strain sensors have temperature characteristics, if the resistance change of this sensor can be detected by some means, the ambient temperature of the place where this sensor is placed can also be detected at the same time as the above information. In other words, semiconductor strain sensors can also be used as temperature sensors.

In this way, the sensor output is like a collection of many pieces of information7.
4 and 1'), so if this sensor output is used, a multi-sensor device can be constructed.

[Example] Fig. 1 is a cross-sectional view of the main parts showing an example of a multi-machine 1-year-old sensor 10 suitable for use in a multi-machine sensor device according to the present invention. A silicon substrate 4 is mounted and fixed on the top of the substrate 1 via a spacer 3. As shown in FIG. 2, the substrate 4 has a rectangular parallelepiped shape in this example, and a circular thin portion 5 is formed approximately in the center thereof, and this is adapted to function as a stylus. Therefore, the thickness of the thin wall portion 5 is approximately 3 to 5 mm, and the diameter of the thin wall portion 5 is 1 mm.
The thickness is selected to be approximately 2 mm.

The mounting position is selected so that the thin portion 5 is located on the upper surface side.

In this example, a pair of semiconductor strain sensors 6a and 6b are attached to predetermined positions on the upper surface of the thin part 5, but these sensors 6a and 6b make up a negligible amount of the mass of the thin part 5. The mass is selected as follows.

A cylindrical case 8 is inserted into the outer periphery of the base 1 to protect the sensors 6a and 6b, and a mesh-like cover 9 is attached to one side of the case 8.

Note that a to d indicate the output terminal bins of the sensors 6a and 6b, and the hole 2 provided in the base 1 is made of thin Fr! This is to allow air communication between the inner surface of the case 65 and the outside of the case 8. Therefore, the example shown in FIG. 1 is a case of an omnidirectional configuration.

Now, in the multifunctional sensor 10 configured in this way, when pressure is applied to the gi membrane 5 from the outside, the thin membrane 5 bends in response to the external pressure.

When the thin film 5 bends, the sensors 6a, 6 attached to it
b expands and contracts in accordance with the amount of deflection, and the resistance values of the sensors 6a and 6b change accordingly. By detecting this change, the magnitude of the external pressure applied to the multi-function f@ sensor 10 can be determined.

FIG. 3 shows an example of the bridge circuit 11 for obtaining sensor output.

In this example, the sensors 6a and 6b described above are connected between the terminals IL and 0 and between the terminals A and C, and between the terminals A and D and between the
A fixed resistor Ra is provided between the terminals d and d.

Rb is connected and adjusted in advance to be stable when no external pressure is applied.

In this bridge configuration, the positions of the sensors shown in FIG. 1 are selected so that, for example, when sensor 6a detects positive pressure, the other sensor 6b detects negative pressure.

A constant current circuit 50 as shown in FIG. 6 is connected between terminals a and b.

FIG. 4 shows an example of a multi-equipment sensor device 20 using the multi-equipment sensor 10.

The sensor outputs obtained at output terminals c and d of the bridge circuit 11 are supplied to the second sensor amplifier 23 via the first normal rotation amplifiers 21 and 22, respectively.

As shown in the figure, the sensor amplifier 23 is composed of a pair of comparators 24 and 25 connected in series, and the final stage amplifier 25
is provided with a volume VR for offset adjustment.

An AC voltage Vd corresponding to the external pressure applied to the multi-R71 sensor 10 is output to the output terminal 25 of the sensor amplifier 23. This AC voltage is an output that corresponds to a range from minute external pressure to permissible external pressure, and as mentioned in 17 above, if this sensor is installed in a manufacturing machine installed in a factory, the output from this manufacturing machine is Signals corresponding to various pressure sounds including vibrations will be detected.

Therefore, if this AC voltage Vd is filtered according to the purpose, only the target signal can be detected.

For example, if the vibration frequency of a manufacturing machine is several tens of Hz or less, by connecting a filter that passes that frequency range, you can pick up only the signals in that range, or if you want to pick up the sounds around the manufacturing machine. If you use a filter of about 50Hz to 3KHz,
Only audio signals can be selectively detected.

It is easy to understand that if you want to detect a signal in a certain narrow frequency range, you can detect a single signal by using a suitable filter.

In such a case, since the frequency range to be detected is narrow, the variation in the obtained AC voltage will also be small, and if this continues, the decomposition value will decrease.In order to increase the 1 decomposition value, as shown in Figure 5. Just add a circuit.

In FIG. 5, 37 is a differential amplifier, one terminal of which is supplied with a predetermined reference voltage (negative voltage) Vr as well as the above-mentioned AC voltage Vd.

For this purpose, a reference voltage source 31 is provided. This is composed of a resistor 31A and a Zener diode 31B, and the voltage obtained from this is passed through a filter 32 and an adjustment resistor 3.
3 and a relay set switch circuit 35 to the above-mentioned one terminal.

The switch circuit 35 is controlled to be turned on manually or automatically when a high resolution threshold is required. A control voltage for this purpose is supplied to the terminal 36.

As a result, one terminal of the differential amplifier 37 has (Vd-Vr
) is supplied, this differential voltage is differentially amplified, and its output is band-limited by the filter 38. The frequency range to be limited is determined depending on the purpose.

By using the differential voltage in this way, the difference between the AC voltage ■d and the reference voltage Vr is amplified, so minute fluctuations that change within the required frequency range can be magnified and detected. can be made higher.

The output of the filter 38 is phase inverted by an inverter 39 as required, and this phase inverted output and the output of the filter 38 are selected by a switch 40 and output to an output terminal 41. Switch 40 may be manual or automatic.

In the bridge circuit 11 shown in FIG. 3, the sensor 6a or 6b may be replaced with a resistor Rb or Ra. In that case, both the sensors 6a and 6b can detect positive pressure or negative pressure. , the location of the sensor mounting shown in FIG. 1 is selected.

FIG. 6 is a configuration diagram showing an example of the constant current circuit 50. The reason for providing the constant current circuit 50 is as follows.

As is well known, semiconductor strain sensors have temperature characteristics, and the strain characteristics of the sensor, and therefore the resistance value of the sensor, change depending on the temperature. Therefore, unless temperature compensation is performed, it is not possible to obtain a sensor output that is independent of temperature.

Therefore, a constant TrL flow circuit 50 is connected to the bridge circuit 11 so that the sensor output (it pressure) obtained from the terminals c and d does not change even if the resistance value of the sensor changes depending on the temperature.

In FIG. 6, 51 is a reference voltage source, and this reference voltage vO is supplied to a child terminal of a voltage comparator 53 via a filter 52, and a negative power source -B is connected to one terminal of the voltage comparator 53 through a resistor 54.
Supplied via. This one terminal is connected to the b terminal of the bridge circuit 11 shown in FIG.

Further, the output of the voltage comparator 53 is supplied to the transistors Q for bar and fa, and the emitter output thereof is supplied to the a terminal of the bridge circuit 11.

In this configuration, the temperature changes and the sensors 6a, 6b
When the resistance value changes, the current flowing to the b terminal of the bridge circuit 11 changes. This current change is converted into a voltage change by the resistor 54, which is compared with a reference voltage, and the emitter voltage of the transistor Q changes in proportion to the difference.

For example, when the resistance value of the sensor becomes smaller, the comparator 53
The comparative output of becomes larger, the emitter voltage becomes higher,
In conjunction with this, the voltage supplied to terminal a is increased, so that the current flowing between terminals a and b becomes constant, and sensor outputs that are unaffected by temperature changes can be obtained at terminals c and d.

By the way, in the constant current circuit 50 shown in FIG. 6, since the voltage obtained at one terminal of the comparator 53 corresponds to the temperature change of the sensors 6a and 6b, this voltage fluctuation is due to the placement of the sensors 6a and 6b. It accurately reflects the atmospheric temperature at the location.

Therefore, by detecting the voltage obtained at one terminal of the comparator 53, it is possible to measure the ambient temperature at the location where the sensors 6a and 6b are placed. Specifically, if the voltage obtained at one terminal of the comparator 53 is supplied to a converter (particularly one not shown) for voltage-to-temperature conversion, and the output is used to drive a temperature display meter, etc. The ambient temperature at the location where the sensors 6a and 6b are placed can also be measured at the same time.

[Effects of the Invention] As explained above, according to the configuration of the present invention, a semiconductor strain sensor is used as an external pressure detection element, so that
It has the following characteristics.

First, semiconductor strain sensors are resistant to dust and oil, and their detection performance is hardly affected even if particles adhere to the semiconductor strain sensor or thin film.In contrast, when using a condenser microphone, as is well known, Dust generated in the factory and s! from manufacturing equipment. If spilled oil or the like adheres to a condenser microphone, this can deteriorate the characteristics of the microphone and significantly shorten the life of the microphone.

For this reason, it has the characteristic of being able to withstand use for 1 minute in places with poor usage environmental conditions.

Furthermore, by attaching this to a thin film, this multifunctional sensor can act as a pressure sensor, and a sensor output proportional to the external pressure applied to it can be obtained. It is possible to detect vibrations over a wide range, even beyond that range, and by performing appropriate filter processing,
This means that the necessary information can be separated from the information in a high frequency range and detected from a single sensor.

Therefore, it can be used not only as a pickup device for vibration detection, but also as a normal microphone.

Furthermore, since the semiconductor strain sensor has temperature characteristics, by detecting the resistance change of this sensor using some means, it is possible to simultaneously detect the ambient temperature of the place where this sensor is placed and the above information. become. In other words, the semiconductor strain sensor can also be used as a temperature sensor.

In this way, the sensor output is obtained with a large amount of superimposed information, so if you process this sensor output in a circuit according to the purpose of use, you can use a single sensor to create a multi-functional sensor. It has the feature of being able to configure a device.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the main parts of an example of a multi-function sensor, Figure 2 is its plan view, Figure 3 is a connection diagram of a bridge circuit using the multi-function sensor, Figures 4 and 5 are respectively A connection diagram showing an example of a multifunctional sensor device, and FIG. 6 is a connection diagram showing an example of a constant current circuit. Vd...Sensor output 4...Silicon substrate 6
a, 6b...Semiconductor strain sensor 10...Multi-ATTM sensor 11...Bridge circuit 20...Multi-function sensor device

Claims (1)

[Claims] A pair of semiconductor strain sensors are arranged at predetermined positions on the thin film, and the resistance of the semiconductor strain sensor changes in response to the deflection of the thin film due to external pressure such as sound or vibration. The sensors are bridge-connected, and the two output terminals of the bridge circuit provide a sensor output corresponding to the resistance change caused by the amount of strain in the semiconductor strain sensor, and this sensor output is output as a change in external pressure via the sensor amplifier. In addition, the atmospheric temperature at the location where the semiconductor strain sensor is placed is also detected from voltage fluctuations occurring in a circuit system that detects a change in resistance due to a change in temperature of the semiconductor strain sensor. A multifunctional sensor device.