JP2007012019A - Sensor device - Google Patents

Abstract

Provided is a sensor device capable of easily configuring a highly versatile measurement system.
A sensor device includes a load cell (sensor body) that outputs a voltage signal corresponding to an applied load, a circuit board, and a power supply unit. Housed in the body 18. The circuit board 14 is equipped with a strain amplifier 24, an A / D conversion circuit 26, a CPU 30, and the like, which perform predetermined signal processing on the voltage signal output from the load cell 12 to obtain measurement result data. It functions as a signal processing means to acquire. The circuit board 14 is also equipped with a USB interface 28 that functions as a communication means for exchanging various types of information including the measurement result data with an external information processing apparatus by USB communication. By providing the USB interface 28, the number of sensor devices 10 connected to a single external information processing device can be easily increased or decreased.
[Selection] Figure 1

Description

  The present invention relates to a sensor main body that detects a physical quantity to be measured and a sensor device in which various devices related to the sensor main body are unitized.

  Conventionally, sensors such as load cells are widely known. The sensor outputs an analog detection signal indicating a physical quantity to be measured, for example, a voltage signal. An analog detection signal such as a voltage signal output from the sensor is amplified by an amplifier, converted to a digital value by an A / D converter, and output to an information processing apparatus via a communication line such as RS232C. Here, conventionally, amplifiers, A / D converters, and the like have used independent devices separate from the sensors. Therefore, the user needs to connect a sensor, an amplifier, an A / D converter, and the like when measuring the physical quantity, which is troublesome. Further, when separate and independent devices are used, there is a problem that analog signal lines tend to be long and are easily affected by noise.

  Therefore, Patent Documents 1 and 2 below disclose a load cell device in which an amplifier and an A / D converter are housed in the same casing as a load cell that is a type of sensor and integrated with the load cell. According to this, the trouble of connecting each of them can be omitted, and an analog signal line can be omitted, so that the influence of noise can be reduced.

JP 54-030881 A Japanese Patent Laid-Open No. 08-075572

  By the way, a plurality of sensors are often used simultaneously. For example, when the load cell device is used for a four-point support hopper, a total of four load cell devices are provided, one for each of the four support portions. And the measurement result of these four load cell apparatuses was output to the information processing apparatus, and the added value was obtained as the hopper weight. For the purpose of improving detection accuracy, the same physical quantity is detected by a plurality of sensors, and the detected values from the obtained sensors are often averaged by an information processing apparatus. Conventionally, an RS232C communication line has been used for connection between the sensor and the information processing apparatus. However, when connecting with RS232C, only one sensor can be connected to one RS232C port provided in the information processing apparatus. For this reason, the number of sensors that can be connected to a single information processing apparatus is limited to the number of RS232C ports provided in the information processing apparatus. Therefore, when the number of sensors increases with the configuration change of the measurement system, it is necessary to increase the number of information processing devices, which reduces the versatility of the system. Patent Documents 1 and 2 do not consider connection with such an information processing apparatus, in particular, highly flexible connection.

  Accordingly, an object of the present invention is to provide a sensor device that can easily configure a highly versatile measurement system.

  The sensor device of the present invention includes a sensor main body that detects a physical quantity to be measured, a signal processing unit that performs predetermined signal processing on a detection signal output from the sensor main body to obtain measurement result data, and a network Communication means for exchanging various types of information including the measurement result data with an external information processing apparatus via any one of communication, USB communication, and power line communication; and at least a sensor body, signal processing means, and communication means And a single housing for housing the device.

  In a preferred embodiment, the sensor body is a momentum sensor that detects the momentum of the object or a mechanical quantity sensor that detects the amount of dynamics of the object. As the mechanical quantity sensor, a load cell for measuring the applied pressure is applicable. An example of the momentum sensor is an acceleration sensor that measures the acceleration of an object.

  In another preferred aspect, the signal processing means includes at least an amplification means for amplifying the analog detection signal output from the sensor body, and an A / D conversion means for converting the amplified analog detection signal into a digital signal. . The signal processing means further converts the detected value detected by the sensor body into a unit of a physical quantity to be measured and calculates it as measurement result data based on the detection signal digitally converted by the A / D conversion means. It is desirable to provide. It is desirable that the signal processing means further includes a correction means for correcting the measurement result data based on the correction value obtained by the calibration work.

  As another preferable aspect, when a reference physical quantity is given to the sensor body, storage means for storing a detection value that should be output from the sensor body as a reference detection value, and a reference to the sensor body in practice. When the physical quantity is given, a correction value used for correcting the measurement result data is calculated based on a comparison between the actually detected detection value actually output from the sensor body and the reference detection value stored in the storage means. Calibration means.

  As another preferred aspect, a command storage means for storing a plurality of commands common to the external information processing apparatus and processing contents indicated by each command, and a command transmitted / received between the external information processing apparatus Command interpreting means for interpreting the contents with reference to the command storage means, and exchange of instructions with the external information processing apparatus is performed via commands.

  As another preferred embodiment, an identifier of the sensor device recognized by the external information processing device is posted on the outer surface of the housing. Furthermore, it is preferable that an output port for outputting a signal for monitoring the sensor device is provided separately from the communication unit. In this case, it is preferable that the information processing apparatus further includes a presentation unit that presents a message to the user via the output port when a specific signal is transmitted from the external information processing apparatus. Further, it is preferable that an input port for inputting a signal for supporting measurement of the sensor device is provided separately from the communication unit. In this case, it is further provided with an operator that is turned ON / OFF by the user, and the communication means transmits the ON / OFF status of the operator inputted via the input port to the external information processing apparatus. desirable.

  By applying the present invention to a load cell device, a load cell that outputs a voltage signal corresponding to an applied load, and a signal that performs predetermined signal processing on the voltage signal output from the load cell to obtain measurement result data Processing means; communication means for exchanging various types of information including the measurement result data with an external information processing device by network communication or USB communication; power supply means for supplying drive power to the signal processing means and the load cell; A load cell device including a load cell, a signal processing unit, a communication unit, and a single housing that houses a power supply unit can be obtained.

  According to the present invention, a communication interface of any one of network communication, USB communication, and power line communication is provided. According to these communication interfaces, the number of sensor devices connected to the external information processing apparatus can be easily and appropriately increased or decreased. As a result, a highly versatile measurement system can be easily configured.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a schematic configuration of a sensor device 10 according to an embodiment of the present invention. This sensor device 10 is a device using a load cell that measures a load by utilizing the properties of a strain gauge 22 or the like as a sensor body. The sensor device 10 of the present embodiment has a particularly suitable configuration when the measurement result is used by an external information processing device (for example, a personal computer). In particular, the configuration is suitable when the measurement results of the plurality of sensor devices 10 are used in a single information processing device.

  The load cell 12 functions as a sensor body, and includes a strain generating portion 20 and a strain gauge 22. When the strain generating portion 20 is deformed by applying a load, a voltage signal is output from the strain gauge 22. The strain generating portion 20 is a columnar, beam-like, or diaphragm-like elastic body, and undergoes minute deformation upon receiving a load. The strain gauge 22 is attached to the strain generating portion 20 and generates a voltage corresponding to the deformation amount of the strain generating portion 20. The voltage generated in the strain gauge 22 is detected by a bridge circuit (not shown) and output to the circuit board 14.

  The circuit board 14 is a board on which the CPU 30, the memory 32, the A / D conversion circuit 26, the strain amplifier 24, and the like are mounted. The circuit board 14 is accommodated in the housing 18 together with the load cell 12. The voltage detected by the bridge circuit is input to the strain amplifier 24 of the circuit board 14. The strain amplifier 24 amplifies the voltage output from the load cell 12 and then outputs the amplified voltage to the A / D conversion circuit 26. At this time, processing such as noise removal is performed as necessary. The A / D conversion circuit 26 converts the analog voltage signal output from the distortion amplifier 24 into a digital value. The voltage signal converted into a digital value is stored in the memory 32 as original data.

  In addition to the original data, the memory 32 stores various setting values, memo data, programs, command information, and the like. The set value stored in the memory 32 includes a correction value used for correction processing of original data. This correction value is acquired and corrected during calibration work of the sensor device 10 that is performed periodically.

  The memo data is various information required by the user, and includes performance information of the sensor device 10 recorded at the time of shipment, user information recorded by the user, and the like. The performance information includes information such as an upper limit value and a lower limit value of the measured load of the load cell 12 and an allowable temperature range. These pieces of information are stored at the time of shipment and are not changed thereafter. On the other hand, the user information is information that can be appropriately recorded, changed, and deleted by the user, and includes, for example, the management number of the sensor device 10 and the installation location. The user can store these pieces of information in the memory 32 via USB communication described later. Also, the memo data can be read out by the information processing apparatus via USB communication as appropriate. Therefore, the user can know the performance information of each sensor device 10, the installation location, and the like even at a location away from the sensor device 10.

  The original data stored in the memory 32 is subjected to signal processing such as correction processing and physical quantity conversion processing by the CPU 30, and then output to the external information processing apparatus via the USB interface 28 as measurement result data. The The contents of the signal processing performed by the CPU 30 will be described in detail later.

  Further, command information is also stored in the memory. The command is a command sentence exchanged with the external information processing apparatus. In the memory, a plurality of commands and processing contents indicated by the commands are associated with each other and stored as command information. The CPU interprets commands exchanged with the external information processing apparatus with reference to the command information.

  The USB interface 28 is an interface for enabling USB communication with an external information processing apparatus, and includes a USB port, a program necessary for USB communication, and the like. As is well known, USB is one of serial interface standards. Measurement result data, memo data, and the like measured by the sensor device 10 are output to the external information processing apparatus via the USB interface 28. By providing the USB interface 28, the sensor device 10 functions as a kind of USB device for the external information processing apparatus. Then, by causing the sensor device 10 to function as a kind of USB device, the number of load cell devices that can be connected to the external information processing device can be easily increased or decreased. That is, normally, the information processing apparatus has a plurality of USB ports, and USB devices can be connected by the number of ports. Further, by providing a USB HUB that is a line concentrator for branching and relaying a plurality of USB cables between the information processing device and the USB device, more USB devices can be connected. In other words, the number of connectable USB devices can be appropriately increased or decreased by appropriately using the USB HUB. Therefore, if the USB HUB 100 is interposed between the information processing device and the load cell device, the number of sensor devices 10 connected to a single information processing device can be easily increased. As a result, a highly versatile load measuring system can be easily configured.

  The CPU 30 functions as a control unit that controls the described distortion amplifier 24, the A / D conversion circuit 26, the USB interface 28, and the like. Further, the CPU 30 interprets a command sent from the information processing apparatus via the USB interface 28 and executes a process according to the command. This command will be described in detail later. Furthermore, the CPU 30 performs signal processing such as correction processing and physical quantity conversion processing on the original data stored in the memory 32 as necessary. This will also be described in detail later.

  The power supply unit 16 supplies driving power for the circuit board 14 and the load cell 12, and is a portable power source such as a dry battery or a battery. In addition, it is good also as a form which receives electric power supply from the exterior, without using this portable power supply. If the USB interface 28 having a bus power function is used, the power supply unit 16 is not necessary, and the USB interface functions as a power supply unit. That is, some recent USB interfaces 28 have a bus power function that can supply power via a USB cable. If the USB interface 28 equipped with the pass power function is used, it is possible to supply 5 V and 500 mA, so that the power supply unit 16 is not necessary.

  The load cell 12, the circuit board 14, and the power supply unit 16 are all fixed and accommodated inside a single casing 18. Therefore, the user can easily handle the sensor device 10 without being aware of the strain amplifier 24, the A / D conversion circuit 26, and the like. That is, conventionally, load cells, strain amplifiers, A / D converters, and the like are all separate devices housed in separate housings. Therefore, when the load measurement is performed using the load cell, the user has to select and prepare a strain amplifier, an A / D conversion device, a power supply device, etc. according to the performance of the load cell, and connect them. . Currently, there are many types of strain amplifiers on the market, and it is complicated to select one according to the performance of the load cell from these. In addition, the operation of connecting the selected strain amplifier or the like is troublesome for the user. On the other hand, in the present embodiment, a strain amplifier 24 or the like corresponding to the performance of the load cell 12 is incorporated in the circuit board 14 in advance, and the circuit board 14 is accommodated in a case 18 that is shared with the load cell 12. . This eliminates the need for selecting and connecting a strain amplifier and the like during load measurement, and allows the user to easily perform load measurement. Further, by housing an amplifier or the like in the same housing 18 as the load cell 12, the distance of the analog signal line can be shortened, and the influence of noise can be reduced.

  Next, signal processing for original data performed by the CPU 30 of the sensor device 10 will be described. The voltage signal output from the load cell 12 is amplified by the distortion amplifier 24, converted to a digital value by the A / D conversion circuit 26, and stored in the memory 32 as original data. Since the voltage value output from the load cell 12 is proportional to the load applied to the sensor device 10, if there is original data obtained by amplifying and A / D converting the voltage value, the magnitude of the applied load can be understood for the time being. It has become. However, the original data indicating the voltage value is difficult to handle for a user who intends to measure the load. Therefore, the CPU 30 executes signal processing for converting the original data into a physical quantity desired by the user. Specifically, the voltage value indicated by the original data is converted into a load value (N) desired by the user. The converted data is output as measurement result data to the external information processing apparatus via the USB interface 28. In the external information processing apparatus, the data converted into the load value is displayed, so that the user can easily recognize the measurement result.

  By the way, this voltage / load conversion is performed based on a preset voltage output characteristic (ratio of output voltage value to additional load). This voltage output characteristic is set to a predetermined value when the sensor device 10 is shipped. Therefore, in the case of the sensor device 10 immediately after shipment, an accurate additional load value can be obtained by performing voltage / load conversion based on a preset initial voltage output characteristic. However, this voltage output characteristic changes depending on the usage environment of the sensor device 10 and aging. For example, the load cell 12 that outputs a voltage of 1 mV at 1N at the time of shipment may have a voltage output of 0.9 mV at 1N due to deterioration or the like. In this case, when physical quantity conversion is performed based on the initially set voltage output characteristics, an accurate additional load amount cannot be obtained.

  Therefore, conventionally, the user has periodically performed calibration work and acquired the voltage output characteristics at that time. Specifically, a reference load is applied to the load cell 12, and the voltage output characteristics at that time are calculated based on the output voltage value. Then, as a result of the calibration work, the value of the output voltage is corrected based on the obtained voltage output characteristics. However, it is not only complicated for the user to correct the output voltage value, but also the final measurement result is inaccurate due to a correction calculation error or forgetting calculation.

  Therefore, the CPU 30 of the sensor device 10 according to the present embodiment also performs correction processing of the measurement result. That is, based on the correction value stored in the memory 32 in advance, the original data or the measurement result data after the physical data conversion of the original data is corrected. By performing correction processing collectively with the sensor device 10, the user can obtain a more accurate measurement value more easily. The correction value stored in the memory 32 is updated every time calibration is performed. In the sensor device 10 of the present embodiment, the correction value stored in the memory 32 is automatically calculated by the CPU 30 during calibration work.

  Next, commands used in USB communication between the sensor device 10 and the external information processing device will be described. The command is a command statement indicating a predetermined processing content, and the sensor device 10 and the external information processing device store a common command. When receiving a command from the external information processing device, the CPU 30 of the sensor device 10 interprets the command and executes a process according to the content. The types of commands exchanged between the two apparatuses include a data transmission / reception start / end command, a calibration work start / end command, a memo data recording / reading command, and various error notification commands. The data transmission / reception start command is a command transmitted from the external information processing apparatus to the sensor apparatus 10, and the sensor apparatus 10 that has received the command transmits the measured result data to the external information processing apparatus. This measurement result data is continuously transmitted until a data transmission / reception end command is transmitted from the external information processing apparatus. At this time, the transmitted measurement result data is data that has been subjected to physical quantity conversion processing and correction processing. Therefore, the user can use the data transmitted to the external information processing apparatus as it is.

  The calibration work start command is a command transmitted from the external information processing apparatus to the sensor device 10. This command is transmitted when the sensor device 10 is calibrated. The sensor device 10 that has received the command switches the drive mode from the normal measurement mode to the calibration mode. The normal measurement mode is a mode for performing normal load measurement. The calibration mode is a mode for calibration work. When the driving mode of the sensor device 10 is the calibration mode, the user applies a predetermined reference load (for example, 1N) to the sensor device 10. The output voltage from the load cell 12 with respect to the addition of the reference load is temporarily stored in the memory 32 as a calibration voltage value. The memory 32 stores in advance an output voltage value that should be originally obtained when a reference load is applied, that is, a reference voltage value. The CPU 30 calculates a difference amount between the calibration voltage value and the reference voltage value, and stores the difference amount in the memory 32 as a correction value. In the subsequent load measurement, the output voltage value is corrected based on this correction value. When the calculation of the correction value is completed, the CPU 30 transmits a calibration work end command to the external information processing apparatus and switches the drive mode to the normal measurement mode. When the external information processing apparatus receives the calibration work end command, the external information processing apparatus presents the normal end of the calibration work to the user. If the difference between the calibration voltage value and the reference voltage value is too large, the CPU 30 of the sensor device 10 determines that there is some problem in the calibration work, and issues a calibration error notification command to the external information processing apparatus. At the same time, the calibration mode is terminated.

  The memo data recording command is a command transmitted from the external information processing device to the sensor device 10. The external information processing apparatus also transmits memo data that is data to be recorded together with the command. Receiving the command, the CPU 30 stores the memo data transmitted together in the memory 32. The contents of the memo data can be appropriately set by the user. For example, the installation location and management number of the sensor device 10 are transmitted as memo data. The memo data read command is also a command transmitted from the external information processing apparatus to the sensor apparatus 10, and the sensor apparatus 10 that has received the command transmits the memo data stored in the memory 32 to the external information processing apparatus. Here, as memo data to be transmitted, in addition to user-set memo data recorded by the memo data recording command, performance information of the sensor device 10 stored in the memory 32 at the time of shipment is also transmitted. The external information processing apparatus presents the transmitted memo data to the user. Thereby, the user can recognize the memo data stored in each sensor device 10, for example, the installation location, performance information, and the like even at a location away from the sensor device 10.

  The various error notification commands are commands transmitted from the sensor device 10 to the external information processing device, and there are a plurality of types of error notification commands depending on the error contents. Examples of the error notification command include a calibration error notification command for notifying a problem at the time of calibration work, and an overload notification error that is notified when a measured load exceeds an upper limit value.

  Thus, even if the connected external information processing device is changed by using the command, the sensor device 10 is not affected. That is, even if the external information processing apparatus is changed (for example, change from a measurement-dedicated computer to a personal computer), if a command transmission / reception and interpretation program is installed in the changed external information processing apparatus, the sensor device 10 Can continue to be used. As a result, the versatility of the sensor device 10 can be further improved.

  Next, an example in which load measurement is performed using the sensor device 10 will be described with reference to FIG. FIG. 2 is a configuration example of a measurement system that measures loads at four measurement points with four sensor devices 10 and processes the measurement results with a single personal computer (hereinafter referred to as “PC102”).

  One sensor device 10 is arranged at each of the four measurement points. Prior to the start of measurement, the user preferably stores the installation location and management number as memo data in the memory 32 of each sensor device 10. The memo data is stored via the information processing apparatus. That is, the user inputs memo data to be stored into the information processing apparatus and instructs the storage of the memo data. Upon receiving the instruction, the information processing apparatus transmits the input memo data to the sensor device 10 together with the memo data storage command. The sensor device 10 stores the transmitted memo data in the memory 32. Here, the sensor device 10 of the present embodiment uses a USB for connection to the information processing device. The USB can be easily connected or disconnected by connecting or disconnecting the USB cable 40. Therefore, when recording memo data, particularly an installation location, the portable information processing device 104 such as a notebook personal computer can be used as the information processing device. As a result, the user can actually go to the vicinity of the load cell 12 and visually check the installation location, and then store the memo data in the sensor device 10.

  When the storage of the memo data is completed, the four sensor devices 10 are connected to the single PC 102 by USB. At this time, the sensor device 10 and the PC 102 may be connected via the USB HUB 100. By interposing the USB HUB 100, a large number of sensor devices 10 can be connected to a single PC 102. Further, if the PC 102 has a plurality of USB ports, the plurality of sensor devices 10 and the PC 102 may be directly connected. In any case, by providing the USB interface 28 in the sensor device 10, connection with the PC 102 is facilitated, and a plurality of sensor devices 10 can be connected to a single PC 102.

  If the four sensor devices 10 are connected to a single PC 102, the user operates the PC 102 to acquire and process measurement result data of the four sensor devices 10 thereafter. That is, when the measurement result data is required, the user operates the PC 102 to instruct the start of data transmission. Here, the PC 102 assigns a unique drive name, device name, etc. to each of the four connected sensor devices 10. The user selects the drive name and the like when instructing the start of data transmission. The PC 102 determines which sensor device 10 the instruction is based on the selected drive name and the like, and transmits a command corresponding to the instruction to the sensor device 10.

  For example, when measurement result data of a certain sensor device 10 is necessary, the user inputs a drive name (or device name, etc.) of the sensor device 10 and a data transmission start instruction to the PC 102. The PC 102 that has received the input specifies the sensor device 10 to be designated from the drive name. Then, a data transmission start command is transmitted to the identified sensor device 10. Upon receiving the command, the sensor device 10 transmits measurement result data to the PC 102. The PC 102 displays the transmitted measurement result data on a display or the like.

  Here, the displayed measurement result data is data that has already undergone physical quantity conversion, correction processing, and the like. In the conventional load cell device, conversion from a voltage value to a load value, correction of an error caused by a change in the voltage output characteristic of the load cell, and the like had to be performed by the user himself / herself. However, in the sensor device 10 of this embodiment, these processes are performed by the sensor device 10. Therefore, the user can immediately know the accurate load value by looking at the measurement result data output from each sensor device 10. As a result, the user can easily and accurately measure the load.

  Further, when the user wants to know the performance and installation location of each sensor device 10, the user may input a drive name indicating the sensor device 10 and a memo data read instruction to the PC 102. Upon receiving the input, the PC 102 specifies the sensor device 10 from the drive name, and transmits a memo data read command to the specified sensor device 10. The sensor device 10 that has received the command returns the memo data stored in the memory 32 to the PC 102. The PC 102 displays the returned memo data on a display or the like. Here, the displayed memo data is information such as the performance of the sensor device 10 (measurement upper limit value, resolution, etc.) and the installation location registered by the user. By looking at the memo data, the user can grasp the performance, the installation location, and the like of each sensor device 10 even when the user is away from the sensor device 10.

  Further, when any problem occurs in the sensor device 10, an error notification command is transmitted from the sensor device 10 to the PC 102. The PC 102 that has received the command identifies the sensor device 10 that is the transmission source, and identifies the error content indicated by the command. Then, the drive name indicating the sensor device 10 and the error content are presented to the user. The user can determine what kind of error has occurred in which sensor device 10 from the presented error content and drive name. Thereby, the user can know the state of the sensor device 10 even from a location away from the sensor device 10.

  That is, by mounting the USB interface 28 on the sensor device 10 and enabling connection to the PC 102, the user can operate and monitor the state of the sensor device 10 at a remote location. In the case of USB, a plurality of USB devices can be connected to a single PC 102. Therefore, the user can operate and monitor a plurality of sensor devices 10 with a single PC 102. Furthermore, in the case of USB, the number of connected USB devices can be easily increased or decreased. Thereby, the structure of the whole measurement system can be changed easily.

  Next, the flow of calibration work of the sensor device 10 will be briefly described. As described, the voltage output from the load cell 12 mounted on the sensor device 10 is proportional to the applied load. However, the ratio between the additional load and the output voltage and the output voltage characteristics slightly change depending on the use environment of the load cell 12 and aging. Since accurate load measurement cannot be performed in a state where the output voltage characteristics have changed, calibration work is required to periodically measure the output voltage characteristics of the load cell 12 and reflect the results in the subsequent measurement value calculation. The sensor device 10 according to the present embodiment is configured to perform this calibration work more easily.

  When performing a calibration operation, the user first connects the sensor device 10 to be calibrated to the information processing apparatus via USB. At this time, it is desirable that a portable information processing device such as a notebook computer 104 is used as the information processing device to be connected, and the user is located in the vicinity of the sensor device 10.

  Subsequently, the user operates the information processing device to instruct the connected sensor device 10 to start calibration work. Upon receiving the instruction, the information processing apparatus transmits a calibration work start command to the sensor apparatus 10. The sensor device 10 that has received the command switches the drive mode to the calibration mode.

  On the other hand, the user who gives an instruction to start the calibration work via the information processing device adds a reference load to the sensor device 10. The addition of the reference load is performed, for example, by placing a test piece having a reference weight on the sensor device 10. The load cell 12 of the sensor device 10 outputs a voltage corresponding to the addition of the reference load. The output voltage is amplified and A / D converted, and then temporarily stored in the memory 32. The CPU 30 acquires an average value of voltage values temporarily stored in the memory 32 as a calibration voltage value. Then, the reference voltage value stored in advance in the memory 32 and the calibration voltage value are compared, and the difference amount is calculated. The calculated difference amount is stored in the memory as a correction value. If the correction value is stored in the memory, the sensor device 10 transmits a calibration work end command to the external information processing device and changes the drive mode to the normal measurement mode. Thereafter, the original data is corrected based on the correction value (difference between the reference voltage value and the calibration voltage value) obtained in the calibration operation.

  As described above, according to the present embodiment, physical quantity conversion and correction processing are performed in the sensor device 10, so that accurate measurement values can be obtained more easily. In addition, by installing the USB interface 28 and enabling USB connection with the information processing apparatus, the versatility of the entire measurement system can be further improved. In addition, by providing a drive mode and a calibration work mode dedicated to calibration work, calibration work that has been complicated in the past can be performed more easily.

  In the present embodiment, the sensor device using the load cell as the sensor body has been described, but other types of sensors may be used as the sensor body. For example, as shown in FIG. 3, a semiconductor pressure sensor 12a may be used as the sensor body instead of the strain gauge pressure sensor (load cell 12). In this case, a DC amplifier 24a may be provided between the pressure sensor 12a and the A / D conversion circuit 26 instead of the strain amplifier 24 (see FIG. 1).

  Further, as shown in FIG. 4, the present embodiment may be applied to the acceleration sensor 12b. The amplifier 24b provided between the acceleration sensor 12b and the A / D conversion circuit 26 is appropriately changed according to the type of the acceleration sensor 12b. For example, when the acceleration sensor 12b is a strain gauge type, a strain amplifier is used, and when the acceleration sensor 12b is a piezoelectric type, a charge amplifier is used. Further, as shown in FIG. 5, the present embodiment may be applied to the torque sensor 12c. Also in this case, an amplifier 24 corresponding to the type of the torque sensor 12c may be provided between the torque sensor 12c and the A / D conversion circuit 26.

  When any sensor is used, these sensor bodies are housed in the same casing 18 together with the amplifier, the A / D conversion circuit, etc. selected according to the sensor body, as in the above-described embodiment. A highly versatile measurement system can be configured by performing the signal processing of the detection signal and exchanging information via the USB interface.

  In the present embodiment, the USB interface 28 is used as a communication interface, but a LAN interface may be used. The configuration of the measurement system in this case is shown in FIG. In FIG. 6, the solid connection line indicates the LAN cable 42, and the broken connection line indicates the power cable 44. When a LAN interface is provided, each sensor device 10 is connected to an information processing device (PC 102) via a network 114 such as a LAN or the Internet by relaying a HUB 110 or a router 112. Thus, the versatility of the measurement system can be further improved by connecting the sensor device 10 and the PC 102 to the network.

  That is, since the USB connection has a limit in the cable length, the distance between the sensor device 10 and the PC 102 cannot be increased too much. On the other hand, in the case of network connection, there is no limitation on the distance between connections, and the sensor device 10 and the PC 102 may be separated by a long distance. In addition, there is no upper limit to the number of sensor devices 10 connected to the PC 102, and more sensors can be connected.

  Further, in the case of network connection, communication with the sensor device 10 is possible from any PC 102 as long as it is connected to the network. Therefore, the measurement results of a plurality of sensor devices 10 can be handled simultaneously by two or more PCs 102. Further, calibration work or the like can be performed by a PC (for example, a portable PC) disposed in the vicinity of the sensor device 10, and measurement result data can be monitored by a PC disposed at a position away from the sensor device 10. It is. That is, the versatility of the measurement system can be further improved by providing a LAN interface instead of the USB interface.

  FIG. 6 shows a system configuration when each sensor device 10 receives power supply from the outside. That is, each sensor device 10 is connected to the outlet 50 via the power cable 44. However, the power supply cable 44 can be omitted by providing a portable power source such as a dry battery inside the sensor device 10. Further, it is possible to supply power to the sensor device 10 by using a LAN interface having a PoE (Power over Ethernet (registered trademark)) function as a LAN interface. If the PoE LAN interface is used, neither the power cable 44 nor the portable power supply is required. As a result, the sensor device 10 can be further miniaturized and the measurement system can be further simplified. Furthermore, if a wireless LAN interface is used, the installation location of the sensor device 10 can be freely changed, and a more versatile measurement system can be configured.

  In addition to the USB and LAN communication interfaces, it is also desirable to use a power line communication (PLC) interface. The PLC is a communication mode in which a harmonic signal is superimposed on a power cable and bidirectional communication is performed using a power line as a transmission path. This PLC has the advantage that an existing outlet or the like can be used as it is and can be connected to a communication environment simply by plugging the power cable into the outlet.

  FIG. 7 is a diagram illustrating a configuration of a measurement system when a PLC is used as a communication interface. In this case, each sensor device 10 is connected to the PLC modem 120 via the LAN cable 42 and the HUB 110. The PLC modem 120 is connected to the indoor power supply wiring network 122 via the power cable 44 and the outlet 50. The information processing apparatus 102 is also connected to the indoor power supply wiring network 122 via the LAN cable 42, the HUB 110, the PLC modem 120, the power cable 44, the outlet 50, and the like. In the PLC, the indoor power supply wiring network 122 functions as a network network. Therefore, the sensor device 10 and the information processing device 102 connected to the indoor power wiring network 122 via the PLC modem 120 or the like can perform bidirectional communication. The power cable 44 extending from the outlet 50 is branched into a path that inputs to the PLC modem 120 for bidirectional communication and a path that directly inputs to each sensor device 10 and the information processing apparatus 102 for power feeding. Yes.

  FIG. 8 is a diagram showing a configuration of a measurement system when the PLC modem 120 is built in the sensor device 10 or the like. In the illustrated example, a PLC modem 120 is built in the sensor device 10, and a single power cable 44 is connected to each sensor device 10. The line of the power cable 44 is branched into a communication path and a power supply path inside the sensor device 10. Therefore, in this case, both power supply and communication can be performed simply by plugging the power cable 44 connected to each sensor device 10 into the outlet 50. In addition, the number of sensor devices 10 connected to the information processing device 102 can be increased or decreased as appropriate by inserting and removing from the outlet 50. As a result, a highly versatile measurement system can be configured very easily.

  In addition, it is desirable to use a port having a waterproof function as a port of various communication interfaces described above, for example, a USB port or a LAN port. By using such a port, measurement in a place with a lot of moisture is also possible.

  When a plurality of sensor devices 10 are used, it may be desired to specify which sensor device 10 outputs each detection value output and displayed on the information processing device 102. For example, there are cases where it is desired to use only the detection values at the sensor device 10 arranged at a predetermined position among the detection values output from the plurality of sensor devices 10. In this case, the information processing apparatus 102 needs to specify a detection value indicated by a desired sensor. However, the information processing apparatus 102 only outputs and displays the detection value of each sensor device 10, and cannot recognize the arrangement position or the like of the sensor device 10 that has detected each detection value. Therefore, it is difficult to specify a detection value from the sensor device 10 arranged at a predetermined position. Therefore, the sensor device 10 may be provided with an input port (not shown) separately from the ports of various interfaces, and the sensor device may be specified by the input signal. For example, as shown in FIG. 9, a contact 36 is provided as an manually operated operator at the input port of the sensor device 10, and the ON / OFF state of the contact is output and displayed on the information processing device 102. May be. In this case, among the plurality of sensor devices 10, only the contact 36 of the sensor device 10 to be used for measurement is turned on in advance, and the contacts 36 of other sensor devices 10 are turned off. This ON / OFF state is output to the information processing apparatus 102. Therefore, the user can easily specify the detection value of the desired sensor device 10 by monitoring the contact ON / OFF state output to the information processing apparatus 102. Note that the signal input to this input port may be used not only for specifying the detection value but also for detecting the timing for starting and ending the measurement.

  In some cases, it is desired to specify the sensor device 10 that has output a predetermined detection value among a plurality of detection values displayed on the information processing apparatus 102. For example, in the information processing apparatus 102, when it is confirmed that an error is output from a certain sensor device 10, the sensor device 10 that has output the error is actually identified and the status of the sensor device 10 is confirmed. There is a need to. However, since each sensor device 10 has the same appearance, it is difficult to specify only the sensor device 10 that has output the error from the plurality of sensor devices 10. Therefore, an output port (not shown) may be provided in the sensor device 10 in addition to the ports of various interfaces, and the sensor device may be specified by an output signal from the output port. For example, when a specific signal is transmitted from the information processing apparatus 102, a presentation unit that presents the fact to the user is provided in the output port of the sensor apparatus 10, and the sensor apparatus 10 is identified based on the situation of the presentation unit. You may make it do.

  Specifically, as illustrated in FIG. 10, a lamp 38 that is turned on or off is provided as a presentation unit in accordance with an output signal from the information processing apparatus 102, and the sensor device 10 is specified by the lighting state of the lamp 38. An example is given. In this case, when an error output from a certain sensor device 10 is confirmed in the information processing apparatus 102, the user instructs the information processing apparatus 102 to turn on the lamp of the sensor apparatus 10. The information processing apparatus 102 outputs a signal that instructs the instructed sensor device 10 to turn on the lamp. When the sensor device 10 receives the signal, the sensor device 10 turns on the lamp 38. Since the lighting state of the lamp 38 can be easily visually recognized from the outside, the user can specify the desired sensor device 10 very easily. Note that the present invention is not limited to the lamp 38, and a buzzer or the like may be used as long as it can be recognized by the user from the outside. The signal output from the output port may be used not only for specifying the sensor device but also as a signal for presenting the detection status of each sensor device 10 to the user via the presenting means. Good. For example, in the measurement process, the physical quantity given to each sensor device 10 may be used as a signal for presenting to the user via the presenting means that the physical quantity assigned to each sensor device 10 has reached a designated physical quantity or is within a designated physical quantity range. Good.

  Further, in order to identify the sensor device 10 and the detection value, the information processing device 102 detects an invariant identifier given to each sensor device 10 in advance, and the identifier is detected on the outer surface of the casing 18 of each sensor device 10. It may be printed on. For example, when performing LAN communication, each sensor device 10 is assigned an IP address, and this IP address functions as an identifier recognized by the information processing device 102. In this case, as shown in FIG. 11, an IP address 39 is printed on the outer surface of the casing 18 of each sensor device 10. The user can easily recognize the correspondence between each sensor device 10 and the detection result by comparing the IP address recognized by the information processing device 102 with the IP address printed on the outer surface of the housing 18. can do. As a result, it is possible to easily identify a sensor device that has output an error, or to identify a detection value from a desired sensor device. Further, similarly to the IP address, each sensor device 10 may be identified using a MAC address assigned to the LAN interface.

It is a block diagram which shows schematic structure of the sensor apparatus which is embodiment of this invention. It is a figure which shows the structural example of the load measurement system using a some sensor apparatus. It is a figure which shows schematic structure of the sensor apparatus at the time of applying this embodiment to the pressure sensor of a semiconductor system. It is a figure which shows schematic structure of the sensor apparatus at the time of applying this embodiment to an acceleration sensor. It is a figure which shows schematic structure of the sensor apparatus at the time of applying this embodiment to a torque sensor. It is a figure which shows the structural example of the measurement system at the time of using a LAN communication interface as a communication interface. It is a figure which shows the structural example of the measurement system at the time of using a PLC communication interface as a communication interface. It is a figure which shows the other structural example of the measurement system at the time of using a PLC communication interface as a communication interface. It is a figure which shows the structure of the measurement system at the time of giving an input function to a sensor apparatus. It is a figure which shows the structure of the measurement system at the time of giving an output function to a sensor apparatus. It is a perspective view which shows an example of the external appearance of a sensor apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Sensor apparatus, 12 Load cell, 14 Circuit board, 16 Power supply part, 18 Case, 20 Strain part, 22 Strain gauge, 24 Strain amplifier, 26 A / D conversion circuit, 28 USB interface, 32 Memory, 40 USB cable, 42 LAN cable, 44 power cable, 50 outlet, 100 USB HUB, 102 PC, 104 portable information processing device, 112 router, 114 network network, 122 indoor power wiring network.

Claims (14)

A sensor body for detecting a physical quantity to be measured;
Signal processing means for obtaining measurement result data by performing predetermined signal processing on the detection signal output from the sensor body;
A communication means for exchanging various types of information including the measurement result data with an external information processing apparatus via any of network communication, USB communication, and power line communication;
A single housing that houses at least the sensor body, the signal processing means, and the communication means;
A sensor device comprising: The sensor device according to claim 1,
The sensor main body is a momentum sensor for detecting a momentum of an object or a mechanical quantity sensor for detecting a mechanical quantity of an object. The sensor device according to claim 2,
The sensor device is a load cell that measures an applied pressure. The sensor device according to claim 2,
The sensor device is an acceleration sensor that measures acceleration of an object. The sensor device according to any one of claims 1 to 4,
The signal processing means is at least
Amplifying means for amplifying the analog detection signal output from the sensor body;
A / D conversion means for converting the amplified analog detection signal into a digital signal;
A sensor device comprising: The sensor device according to claim 5,
The signal processing means further converts the detected value detected by the sensor body into a unit of a physical quantity to be measured and calculates it as measurement result data based on the detection signal digitally converted by the A / D conversion means. A sensor device comprising: The sensor device according to any one of claims 1 to 6,
The signal processing means further comprises a correction means for correcting measurement result data based on a correction value obtained by a calibration operation. The sensor device according to claim 7, further comprising:
When a reference physical quantity is given to the sensor body, storage means for storing a detection value that should be output from the sensor body as a reference detection value originally;
Used to correct measurement result data based on a comparison between the actual detection value actually output from the sensor body and the reference detection value stored in the storage means when a reference physical quantity is actually given to the sensor body Calibration means for calculating a correction value to be obtained;
A sensor device comprising: The sensor device according to any one of claims 1 to 8, further comprising:
Command storage means for storing a plurality of commands common to the external information processing apparatus and processing contents indicated by each command;
Command interpreting means for interpreting the contents of commands transmitted to and received from the external information processing apparatus with reference to the command storage means;
A sensor device characterized in that exchange of commands with an external information processing device is performed via a command. The sensor device according to any one of claims 1 to 9,
An identifier of the sensor device recognized by the external information processing device is posted on the outer surface of the housing. The sensor device according to any one of claims 1 to 10, further comprising:
A sensor device comprising an output port for outputting a signal for monitoring the sensor device separately from the communication means. The sensor device according to claim 11, further comprising:
A sensor device comprising presentation means for presenting to a user via the output port when a specific signal is transmitted from an external information processing device. The sensor device according to any one of claims 1 to 12, further comprising:
In addition to the communication means, a sensor device comprising an input port for inputting a signal for supporting measurement of the sensor device. The sensor device according to claim 13, further comprising:
It has an operator that is turned on and off by the user.
The communication device transmits an ON / OFF state of the operation element input via the input port to an external information processing apparatus.

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