JP2008118226A - Detection sensor, controller, and sensor system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detection sensor whose function can be set from outside. <P>SOLUTION: A decision circuit 26 detects a body W to be detected by comparing the level of a photodetection signal S1 output from a photodetecting element 22 with a threshold level, and outputs an output signal S2 corresponding to the comparison result to a transistor T1. Further, an overcurrent detecting circuit 27 detects an overcurrent flowing into the transistor T1 with a voltage signal and when a voltage signal having a predetermined pattern is detected, it is made possible to read and write setting information stored in a register 25. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a detection sensor, a controller, and a sensor system.

Conventionally, for example, a detection sensor used to detect the presence / absence of an object to be detected determines the presence / absence of an object to be detected based on a preset threshold level with respect to a change in the amount of incident light, and according to the determination Output the signal to the controller. In recent years, in order to respond to a function switching request such as output level switching, a detection sensor switches a function by a switch connected to an IC (Integrated Circuit) built in the detection sensor (for example, Patent Document 1).
Japanese Patent Laid-Open No. 10-98369 (paragraph [0027], FIG. 2)

  By the way, in recent years, there is a demand for multifunctional photoelectric sensors including sensitivity, transmission type / reflection type, and L / D ON, and it is conceivable to provide a changeover switch according to each function. However, when the number of changeover switches increases, there is a problem that the number of IC terminals increases and the IC package becomes larger.

  Therefore, a method is conceivable in which setting information is transmitted from a controller or the like to the sensor head, and the function of the sensor head is set based on the setting information. However, this method requires a new terminal and signal line for transmitting the setting information from the controller to the detection sensor, which makes it impossible to use connection cables, connectors, and the like used in conventional photoelectric sensors. It will occur.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide a detection sensor capable of setting a function from the outside.

  In order to achieve the above object, the invention according to claim 1 outputs a physical quantity detection means for outputting a detection signal level corresponding to a physical quantity for detecting the detected object, and an output signal based on the detection signal level. Output means; switch means for performing a switching operation according to the output signal; current detection means for detecting a current flowing through the switch means; storage means for storing setting information relating to the detection operation of the physical quantity detection means; and the switch means The setting information inputted from the outside via the input means can be input to the storage means, and the setting information can be inputted to the input means when a current of a predetermined pattern is detected by the current detection means Input setting means, and the setting information is input to the input means based on the current detected by the current detection means.

According to this configuration, the output means outputs an output signal based on the detection signal level output from the physical quantity detection means to the switch means to detect the detection object. Then, when a current of a predetermined pattern is detected by the current detection means, setting information can be input from the outside to the switch means, and the setting information input to the switch means is input by the input means. Output to storage means. Therefore, the function can be set from the outside of the detection sensor. Further, since the function of the detection sensor can be set by inputting the setting information to the switch means for outputting the output signal, there is no need to newly provide a terminal or a signal line for transmitting the setting information to the detection sensor. The connection cable, connector, etc. used in the photoelectric sensor can be used. In addition, since it is not necessary to load a new configuration in order to read the input setting information, an increase in the size of the detection sensor IC is suppressed.

  According to a second aspect of the present invention, in the detection sensor according to the first aspect, when the current detecting unit detects a current exceeding a normal amount in the switch unit, the output signal from the output unit is intermittently transmitted. An overcurrent protection means for performing an overcurrent protection operation to output to is provided. According to this configuration, an overcurrent protection operation is performed in which an output signal from the output means is intermittently output when a current exceeding a normal amount is detected in the switch means.

  According to a third aspect of the present invention, in the detection sensor according to the second aspect, the input control unit is configured to detect the predetermined pattern by the current detection unit during the overcurrent protection operation by the overcurrent protection unit. When the current is detected, the input means is allowed to input the setting information. According to this configuration, since the output signal is not output from the output means during the overcurrent protection operation by the overcurrent protection means, the current detection means has a predetermined pattern other than a predetermined pattern current flowing from the outside. No current is detected, and malfunction is prevented.

  According to a fourth aspect of the present invention, in the detection sensor according to any one of the first to third aspects, when the input control unit is permitted to input the setting information to the input unit. When the current of the predetermined pattern is detected by the current detection means, the setting information is prohibited from being input to the input means, and the output by the output means is performed. According to the configuration, when the setting unit is permitted to input setting information, a predetermined pattern of current is supplied from the outside to allow the output unit to perform output.

  The invention according to claim 5 is a controller to which the detection sensor according to any one of claims 1 to 4 is connected, and supplies the current of the predetermined pattern to the switch means of the detection sensor. A current source is provided. According to this configuration, a predetermined pattern of current can be supplied to the switch means of the detection sensor.

  The invention according to claim 6 is the controller according to claim 5, wherein the current source includes first current supply means for supplying a predetermined amount of current to the switch means of the detection sensor, and the predetermined amount or more. Second current supply means for supplying current to the switch means, and after supplying the current of the predetermined amount or more in the predetermined pattern, supplying the current of the predetermined amount or more, Current control means for controlling the second current supply means to transmit to the detection sensor. According to this configuration, the function of the detection sensor can be set from the controller.

  The invention according to claim 7 is a detection sensor according to any one of claims 1 to 4, a controller connected to the detection sensor, and receiving a signal by a switching operation of a switch means of the detection sensor; The controller includes a current source for supplying a current of the predetermined pattern to the switch means of the detection sensor. According to this configuration, the output means outputs an output signal based on the detection signal level output from the physical quantity detection means to the switch means to detect the detection object. Then, when a current of a predetermined pattern is detected by the current detection means, setting information can be input to the switch means from the outside, and the switch means is set based on the current detected by the current detection means. Information is input to the input means, and the setting information is output to the storage means by the input means. Therefore, the function can be set from the outside of the detection sensor. Further, since the function of the detection sensor can be set by inputting the setting information to the switch means for outputting the output signal, there is no need to newly provide a terminal or a signal line for transmitting the setting information to the detection sensor. The connection cable, connector, etc. used in the photoelectric sensor can be used. In addition, since it is not necessary to load a new configuration in order to read the input setting information, an increase in the size of the detection sensor IC is suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the detection sensor which can set a function from the outside can be provided.

Hereinafter, an embodiment in which the present invention is embodied in a photoelectric sensor will be described with reference to the drawings.
As shown in FIG. 1, a sensor head 20 is connected to a controller 10 of a photoelectric sensor that detects the presence or absence of an object W to be detected. A connection cable 30 is provided at the sensor head 20, and a connector (not shown) provided at the tip of the connection cable 30 is connected to a connector (not shown) of the controller 10. The sensor head 20 is disposed, for example, above or to the side of the path for transporting the detected object W during use. The element 22 receives the reflected light from the object W to be detected. Then, the sensor head 20 compares the light reception signal level of the light receiving element 22 with the threshold level to determine the presence or absence of the detection object W, and transmits the determination result to the controller 10 via the connection cable 30.

  As shown in FIG. 2, the controller 10 is provided with connector connection terminals P11, P12, and P13, and wirings 30a, 30b, and 30c constituting the connection cable 30 are connected to the connection terminals P11, P12, and P13. . The connection terminal P11 is connected to the high potential power supply Vcc, and the connection terminal P13 is connected to the ground GND. The sensor head 20 operates based on the power supplied through the connection terminal P11 and the wiring 30a.

  The sensor head 20 is provided with a control device 23 composed of a semiconductor integrated circuit device (IC), a light projecting element 21 is connected to the connection terminal P21 of the control device 23, and a physical quantity is connected to the connection terminal P22 of the control device 23. A light receiving element 22 as a detecting means is connected, and a transistor T1 as a switching means is connected to a connection terminal P23 of the control device 23. When the power is supplied, the control device 23 drives the light projecting element 21 to project light. The light is reflected by the object W to be detected, and the reflected light is incident on the light receiving element 22. The light receiving element 22 outputs a light receiving signal S1 having a level corresponding to the amount of incident light. The control device 23 compares the level of the light reception signal S1 with a preset threshold level to determine the presence or absence of the detection object W. Further, the control device 23 outputs an output signal S2 corresponding to the determination result to the transistor T1.

  The transistor T1 is an NPN transistor, the output signal S2 is applied to the base, the collector is connected to the controller 10, and the emitter is connected to the ground via the resistor R1. The transistor T1 is turned on / off in response to the output signal S2, and a current flows through the turned on transistor T1. The controller 10 receives a signal from the sensor head 20, that is, the presence / absence of the detected object W depending on the presence / absence of the current.

  The control device 23 includes a control circuit 24, a register 25, a determination circuit 26 as output means, an overcurrent detection circuit 27 as current detection means, overcurrent protection means, setting means, input means, and input control means, And a register 25 as storage means. The control circuit 24 is connected to the light projecting element 21 via the connection terminal P <b> 21, and the control circuit 24 controls light projection of the light projecting element 21. The determination circuit 26 is connected to the light receiving element 22 via the connection terminal P22. The determination circuit 26 receives the light reception signal S1 output from the light reception element 22, and outputs the output signal S2 output from the control device 23. The determination circuit 26 is connected to the base of the transistor T1 through the connection terminal P23, and the overcurrent detection circuit 27 is connected to the connection terminal P23.

A register 25 is connected to the control circuit 24. The register 25 is a memory capable of holding information even when no operating power is supplied and capable of electrically writing information. For example, an EEPROM, a polysilicon fuse, a zener zap, a flash memory (registered trademark) Etc.

  The control circuit 24 causes the light projecting element 21 to emit light based on the setting information stored in the register 25 to project light. The light receiving element 22 outputs a light reception signal corresponding to the amount of received light to the determination circuit 26. The determination circuit 26 compares the level of the light reception signal S1 with a preset threshold level to determine the presence / absence of the detection object W, and outputs an output signal S2 corresponding to the determination result. Based on the setting information stored in the register 25, the determination circuit 26 operates when the light is on or off. In the present embodiment, when the determination circuit 26 is set to ON when light enters, the transistor T1 is turned on when the light reception signal level is equal to or higher than the threshold level, and when the light reception signal level is lower than the threshold level. The transistor T1 is turned off. When the light receiving signal level is equal to or higher than the threshold level, the determination circuit 26 turns off the transistor T1 when the light receiving signal level is equal to or higher than the threshold level. Turn on.

  The overcurrent detection circuit 27 detects a voltage generated at the base of the transistor T1 according to the current flowing through the transistor T1. Based on the detected voltage, the overcurrent detection circuit 27 determines whether or not an overcurrent flows through the transistor T1. If an overcurrent flows, the overcurrent detection circuit 27 controls the determination circuit 26 to turn off the transistor T1. The so-called overcurrent protection function is provided. The overcurrent detection circuit 27 controls the determination circuit 26 to output an output signal, and turns on and off the transistor T1.

  The connection terminal P12 of the controller 10 is connected to the high potential power supply Vcc via a resistor R2 as a first current supply means. The connection terminal P12 is connected to the CPU 11 as current control means and the current supply circuit 12 as second current supply means. The resistor R2 and the second current supply means constitute a current source. A signal corresponding to ON / OFF of the transistor T1 of the sensor head 20 is input to the CPU 11. Since the connection terminal P12 is connected to the high potential power supply Vcc via the resistor R2, an H level signal is input to the CPU 11 when the transistor T1 is off, and the connection terminal P12 is connected to the ground GND when the transistor T1 is on. Therefore, an L level signal is input to the CPU 11.

  In response to the control signal from the CPU 11, the current supply circuit 12 supplies two different currents (first current and second current) to the sensor head 20, that is, the transistor T1 via the connection terminal P12. As described above, the base voltage of the transistor T1 becomes a potential corresponding to the current supplied from the controller 10, and the overcurrent detection circuit 27 detects the voltage. In the present embodiment, the first current is set to 100 mA, and the second current is set to 200 mA. The base voltage of the transistor T1 is 0.7 V when the first current (100 mA) is supplied, and 1.4 V when the second current (200 mA) is supplied. Therefore, when the current supply circuit 12 supplies no current to the overcurrent detection circuit 27, three types of signals (0V, 0.7V, 1.4V) are input from the CPU 11. The connection terminal P12 is connected to the high potential power source Vcc via the resistor R2, but the resistor R2 is for pulling up the connection terminal P12, and its resistance value is set so that almost no current flows. Has been.

  In this way, when the overcurrent detection circuit 27 detects a voltage corresponding to the current supplied from the controller 10 to the transistor T1, the transistor T1 is connected to the sensor head 20 via the transistor T1 provided for signal output. A signal can be transmitted from the controller 10 to the overcurrent detection circuit 27 for protecting the circuit. Therefore, it is not necessary to newly add a receiving circuit and a terminal to which the circuit is connected in order to acquire setting information from the CPU 11, and the size of the control device 23 can be suppressed.

The operation of the detection mode in which the photoelectric sensor configured as described above detects the detection target W will be described.
The control circuit 24 reads the setting information stored in the register 25, causes the light projecting element 21 to emit light based on the setting information, and irradiates the detected object W with light. The light receiving element 22 receives the reflected light from the reflection surface of the object W to be detected, and outputs a light reception signal S1 having a level corresponding to the amount of received light to the determination circuit 26. The determination circuit 26 compares the level of the light reception signal S1 with the threshold level stored in the register 25 and outputs an output signal S2.

  When the level of the light reception signal S1 is equal to or higher than the threshold level, the transistor T1 is turned on, an L level signal is input to the CPU 11, and the CPU 11 determines that the detected object W has been detected. Further, when the level of the light reception signal S1 is smaller than the threshold level, the transistor T1 is turned off, and an H level signal is input to the CPU 11. The CPU 11 determines that the detected object W has not been detected.

  The overcurrent detection circuit 27 protects the sensor head 20 by stopping the output of the determination circuit 26 (overcurrent protection operation) when an overcurrent is detected in the transistor T1 during the detection operation of the sensor head 20. The overcurrent detection circuit 27 releases the overcurrent protection and restarts the output of the determination circuit 26 when the state where no overcurrent is detected continues for a predetermined time (for example, 1 minute).

Next, the operation in the setting mode for reading or writing the setting information of the photoelectric sensor will be described.
The CPU 11 controls the current supply circuit 12 to supply an overcurrent (for example, 200 mA) to the transistor T1, and after causing the overcurrent detection circuit 27 to perform an overcurrent protection operation, supplies a predetermined pattern of current. Specifically, the CPU 11 controls the current supply circuit 12 to supply a current of 100 mA and a current of 200 mA alternately to the transistor T1 three times every clock from a state where a current of 100 mA is flowing. . Next, the CPU 11 does not supply current to the transistor T1 for 10 clocks, and then supplies a current of 200 mA for 1 clock. Then, the CPU 11 sets a state in which no current is supplied to the transistor T1 for 3 clocks, then supplies a current of 200 mA to the transistor T1 for 1 clock, and then supplies a current of 100 mA. The CPU 11 controls the current supply circuit 12 to supply the current having the above pattern a plurality of times (for example, three times).

  When the current of a predetermined pattern is supplied to the transistor T1, the overcurrent detection circuit 27 detects the voltage signal Vs having a waveform as shown in FIG. When the overcurrent detection circuit 27 detects the voltage signal Vs having a waveform as shown in FIG. 3 a plurality of times (the number of times the current supply circuit 12 supplies a predetermined pattern of current) during the overcurrent protection operation, The setting information stored in the memory 25 can be read or written, and the setting information of the photoelectric sensor is read or written according to the communication procedure shown in FIG. During the detection mode, since a current flows through the transistor T1, there is a possibility that the overcurrent detection circuit 27 detects a voltage as shown in FIG. 3, but as described above, a predetermined value is generated during the overcurrent protection operation. When the voltage signal of this pattern is detected, it is not possible to directly shift from the detection mode to the setting mode, so that malfunction can be suppressed. Further, when the overcurrent detection circuit 27 detects the voltage signal Vs having a waveform as shown in FIG. 3 a plurality of times (the number of times the current supply circuit 12 supplies a predetermined pattern of current) in the setting mode, the overcurrent detection circuit 27 shifts to the detection mode. Then, the output of the determination circuit 26 is restarted.

Here, a write operation for writing the setting information of the sensor head 20 and a read operation for reading the setting information will be described.
<Write operation>
After detecting the voltage signal Vs having the waveform as shown in FIG. 3, the overcurrent detection circuit 27 first controls the determination circuit 26 to turn on and off the transistor T1, thereby causing the CPU 11 to first send the header 41 (type of the sensor head 20). , Information such as device number) is output to the CPU 11. When the CPU 11 receives the header 41 from the overcurrent detection circuit 27, the CPU 11 outputs a command 42 (information on the operation to be performed by the overcurrent detection circuit 27) to the overcurrent detection circuit 27, and from among the functions of the photoelectric sensor. Specify the function to write. Next, the CPU 11 transmits data 43 (setting information corresponding to the designated function) to the overcurrent detection circuit 27. Thereafter, the CPU 11 outputs a delimiter 44 (information indicating a communication break for performing one write operation) to the overcurrent detection circuit 27. The overcurrent detection circuit 27 writes to the register 25 based on the data 43.

  As described above, the overcurrent flowing from the controller 10 to the transistor T1 is detected by the overcurrent detection circuit 27 and written to the register 25, thereby setting the function of the photoelectric sensor provided in the sensor head 20 from the controller 10. Can do.

<Read operation>
After detecting the voltage signal Vs having the waveform as shown in FIG. 3, first, the overcurrent detection circuit 27 outputs the header 41 to the CPU 11 to the CPU 11 as in the write operation. When the CPU 11 receives the header 41 from the overcurrent detection circuit 27, the CPU 11 outputs a command 42 to the overcurrent detection circuit 27 and designates a function to be read from the setting information stored in the register 25. When the overcurrent detection circuit 27 receives the command 42, the overcurrent detection circuit 27 reads the setting information designated from the setting information stored in the register 25, and controls the determination circuit 26 to turn on and off the transistor T1, thereby obtaining the data 43. It transmits to CPU11. And then. When the CPU 11 receives the data 43, it outputs a delimiter 44 to the overcurrent detection circuit 27.

  As described above, the overcurrent detection circuit 27 controls the determination circuit 26 to turn on and off the transistor T1, thereby enabling the setting information to be transmitted to the CPU 11 provided in the controller. As a result, the setting information stored in the register 25 can be read.

As described above, according to the present embodiment, the following effects can be obtained.
(1) The determination circuit 26 detects the detected object W by comparing the level of the light receiving signal S1 output from the light receiving element 22 and the threshold level value, and outputs the output signal S2 corresponding to the comparison result to the transistor T1. Output to. The overcurrent detection circuit 27 detects the overcurrent flowing through the transistor T1 with a voltage signal, and when the voltage signal having a predetermined pattern is detected, the setting information stored in the register 25 can be read or written. did. For this reason, after a predetermined pattern of overcurrent flows from the CPU 11, the setting information is transmitted, so that the register 25 can be written and the function of the photoelectric sensor can be set. In addition, since the setting information is input to the control device 23 via the transistor T1 and written to the register 25, there is no need to provide a new terminal or signal line, and a connection cable used for a conventional photoelectric sensor, Connectors can be used.

  (2) The overcurrent detection circuit 27 acquires the setting information for setting the function of the control device 23 from the CPU 11 by detecting the overcurrent flowing through the transistor T1. Therefore, it is not necessary to newly add a configuration for acquiring the setting information from the CPU 11, and the control device 23 can be prevented from being enlarged.

  (3) Since the condition is that a voltage signal having a predetermined pattern is detected during the overcurrent protection operation, the setting operation is not suddenly moved from the detection operation, and thus malfunction can be suppressed.

(4) The overcurrent detection circuit 27 provided in the sensor head 20 controls the determination circuit 26 to turn on and off the transistor T1, thereby enabling setting information to be transmitted to the CPU 11 provided in the controller. As a result, the setting information stored in the register 25 can be read.

In addition, you may implement each said embodiment in the following aspects.
In the above embodiment, the current value supplied by the current supply circuit 12 is set to 100 mA and 200 mA. However, the current value is not limited to this, and if the value is larger than the current value flowing by turning on and off the transistor T1 during the detection operation, Any value may be used.

  In the above-described embodiment, the photoelectric sensor that detects the presence / absence of the detection target W is embodied. However, the present invention is not limited to this. For example, the photoelectric sensor may be embodied as a displacement sensor that measures the displacement of the reflection surface of the detection target W.

The perspective view of a photoelectric sensor. The block circuit diagram of a photoelectric sensor. The detection waveform figure of an overcurrent detection circuit. Explanatory drawing which shows a communication procedure.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Controller, 11 ... CPU, 12 ... Current supply circuit, 20 ... Sensor head, 22 ... Light receiving element, 23 ... Control device, 25 ... Register, 26 ... Judgment circuit, 27 ... Overcurrent detection circuit, S1 ... Light reception signal, S2 ... output signal, T1 ... transistor, W ... detected object.

Claims (7)

Physical quantity detection means for outputting a detection signal level corresponding to the physical quantity for detecting the detected object;
An output means for outputting an output signal based on the detection signal level;
Switch means for performing a switching operation according to the output signal;
Current detecting means for detecting a current flowing through the switch means;
Storage means for storing setting information related to the detection operation of the physical quantity detection means;
Input means for outputting the setting information input from the outside via the switch means to the storage means;
Input control means for enabling the input of the setting information to the input means when a current of a predetermined pattern is detected by the current detection means,
The detection sensor, wherein the setting information is input to the input unit based on a current detected by the current detection unit. The detection sensor according to claim 1,
And an overcurrent protection unit that performs an overcurrent protection operation for intermittently outputting the output signal from the output unit when the current detection unit detects a current exceeding a normal amount in the switch unit. Detection sensor. The detection sensor according to claim 2,
The input control means permits the input means to input the setting information when the current detection means detects a current of the predetermined pattern during the overcurrent protection operation by the overcurrent protection means. ,
A detection sensor characterized by that. In the detection sensor as described in any one of Claims 1-3,
The input control means, when the input means is permitted to input the setting information, when the current detection means detects the current of the predetermined pattern, the input control means Is prohibited, and output by the output means is performed.
A detection sensor characterized by that. A controller to which the detection sensor according to any one of claims 1 to 4 is connected,
A controller comprising a current source for supplying the predetermined pattern of current to the switch means of the detection sensor. The controller of claim 5, wherein
The current source includes a first current supply unit that supplies a predetermined amount of current to the switch unit of the detection sensor, and a second current supply unit that supplies a current of the predetermined amount or more to the switch unit. ,
Current control for controlling the second current supply means to supply the setting information to the detection sensor by supplying the current of the predetermined amount or more after supplying the current of the predetermined amount or more in the predetermined pattern. Means,
A controller characterized by comprising: The detection sensor according to any one of claims 1 to 4,
A controller connected to the detection sensor and receiving a signal from a switching operation of a switch means of the detection sensor,
2. The sensor system according to claim 1, wherein the controller includes a current source that supplies the predetermined pattern of current to the switch means of the detection sensor.

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