Safety sensor

Abstract

This prevents false actuator detection and intentional disabling of safety sensors. [Solution] The actuator 3 of the safety sensor 1 has an RFID tag 31. The sensor head 2 has an RFID reader 21 and a memory unit. The RFID reader 21 reads the tag information stored in the RFID tag 31 when the actuator 3 is in close proximity. The memory unit stores the sensor information. The tag information and sensor information each include product information of the safety sensor 1. The ON output processing in the sensor head 2 is only possible when the product information contained in the tag information read by the RFID reader 21 matches the product information contained in the sensor information. This makes it possible to suppress false detection of the actuator 3 and intentional deactivation of the safety sensor 1.

Description

Technical Field

[0001] The present invention relates to a safety sensor.

Background Art

[0002] Conventionally, a safety sensor (also called a safety switch) is provided at the entrance and exit of a room where industrial machines and the like are installed. When the door at the entrance and exit is closed, the safety sensor detects the closing of the door, and thereby the power supply to the industrial machine and the like becomes possible. On the other hand, when the door at the entrance and exit is opened, the power supply to the industrial machine and the like becomes impossible.

[0003] As one of the above safety sensors, an RFID-type non-contact safety sensor is used. In the non-contact safety sensor, for example, a sensor head having an RFID reader is attached to the periphery of the entrance and exit of the room, and an actuator having an RFID tag is attached to the door. Then, when the entrance and exit is closed by the door and the actuator approaches the sensor head, the RFID tag of the actuator is read by the RFID reader of the sensor head, and the safety output is turned on at the sensor head, making it possible to supply power to an industrial machine or the like.

[0004] For example, in the safety switch of Patent Document 1, when the actuator approaches the sensor body, the unique ID of the RFID tag of the actuator is read by the sensor body, and when the unique ID matches the unique ID previously stored in the sensor body, the safety output is turned on at the sensor body. Before the safety switch is used, a pairing mode for associating the actuator and the sensor body is executed, and the unique ID of the RFID tag of the actuator is read and stored by the sensor body.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] By the way, in the safety switch described in Patent Document 1, in the pairing mode described above, there is a risk that the safety switch may be intentionally disabled by using another item, such as a transportation IC card or access control card, that is different from the actuator to be paired with the sensor body, and by storing the unique ID of the RFID tag embedded in the other item in the sensor body.

[0007] Furthermore, in safety switches that do not pair the sensor body with the actuator, if an object other than the actuator is brought close to the sensor body, the RFID tag embedded in that object may be mistakenly detected by the sensor body, potentially causing the safety switch to malfunction. In particular, if the wireless communication frequency band of the safety switch is the HF band, many other devices also utilize HF band wireless communication.

[0008] This invention has been made in view of the above problems and aims to suppress false detection of actuators and intentional disabling of safety sensors. [Means for solving the problem]

[0009] One aspect of the present invention is a safety sensor comprising an actuator having an RFID tag, and a sensor head having an RFID reader that reads tag information stored in the RFID tag when the actuator is in close proximity, and a memory unit that stores sensor information. The tag information and the sensor information each include product information of the safety sensor. Authorized processing in the sensor head is only possible when the product information contained in the tag information read by the RFID reader matches the product information contained in the sensor information.

[0010] Aspect 2 of the present invention is a safety sensor according to aspect 1, wherein the tag information includes a unique identifier specific to the actuator. The sensor head determines whether the safety sensor is used in high-code or low-code mode, using the unique identifier. The authorized processing is an initial teaching process that is only executable when the usage information is high-code, which involves storing the unique identifier in the sensor head and including it in the sensor information.

[0011] A third aspect of the present invention is a safety sensor according to aspect 2, wherein the application information is determined based on a signal input to a predetermined terminal provided on the sensor head.

[0012] Aspect 4 of the present invention is a safety sensor according to aspect 2 (or aspect 2 or 3), wherein the initial teaching process comprises: a) the process of continuing the initial teaching process only if the duration of reading the tag information of the RFID tag by the RFID reader is within a first time condition, the unique identifier included in the tag information is stored in the sensor head as a temporary unique identifier; b) the process of continuing the initial teaching process only if, following step a), the state of being unable to read the tag information of the RFID tag by the RFID reader continues within a second time condition, and c) the process of including the unique identifier included in the tag information in the sensor information only if, after step b), the tag information of the RFID tag is read by the RFID reader, the product information included in the tag information matches the product information included in the sensor information, and the unique identifier included in the tag information matches the temporary unique identifier stored in the sensor head.

[0013] Aspect 5 of the present invention is a safety sensor according to aspect 2 (which may be any one of aspects 2 to 4), wherein, after the completion of the initial teaching process, the product information contained in the tag information read by the RFID reader matches the product information contained in the sensor information, the application information is high-coded, and the unique identifier contained in the tag information read by the RFID reader does not match the unique identifier contained in the sensor information, the re-teaching process in the sensor head is made possible. The reteaching process includes the steps of: d) continuing the reteaching process only if the duration of reading the tag information of the RFID tag by the RFID reader is within the range of the third time condition; e) continuing the reteaching process only if, following step d), the state of being unable to read the tag information of the RFID tag by the RFID reader continues within the range of the fourth time condition; and f) following step e), reading the tag information of the RFID tag by the RFID reader, and only if the duration of reading the tag information is within the range of the fifth time condition, the unique identifier included in the tag information is stored in the sensor head as a provisional unique identifier and the reteaching process continues. The process includes: g) continuing the teaching process; g) continuing the re-teaching process only if, following step f), the RFID reader remains unable to read the tag information of the RFID tag within the range of the sixth time condition; and h) after step g), reading the tag information of the RFID tag by the RFID reader, matching the product information contained in the tag information with the product information contained in the sensor information, and matching the unique identifier contained in the tag information with the temporary unique identifier stored in the sensor head, thereby rewriting the unique identifier contained in the sensor information with the unique identifier contained in the tag information.

[0014] Aspect 6 of the present invention is a safety sensor according to any one of aspects 1 to 5, wherein the frequency band used for wireless communication between the RFID reader and the RFID tag is the HF band.

Advantages of the Invention

[0015] According to the present invention, it is possible to suppress false detection of an actuator and intentional invalidation of a safety sensor.

Brief Description of the Drawings

[0016] [Figure 1] It is a plan view of a restricted area where a safety sensor according to the first embodiment is provided. [Figure 2] It is a plan view showing an enlarged view of the vicinity of the safety sensor. [Figure 3] It is a diagram showing a tag memory area. [Figure 4] It is a diagram showing a sensor memory area. [Figure 5] It is a diagram showing the operation of the safety sensor. [Figure 6A] It is a diagram showing the operation of the safety sensor. [Figure 6B] It is a diagram showing the operation of the safety sensor. [Figure 7A] It is a diagram showing the flow of initial teaching processing. [Figure 7B] It is a diagram showing the flow of initial teaching processing. [Figure 8A] It is a diagram showing the flow of re-teaching processing. [Figure 8B] It is a diagram showing the flow of re-teaching processing. [Figure 9] It is a plan view of a safety sensor according to the second embodiment.

Modes for Carrying Out the Invention

[0017] FIG. 1 is a plan view of a restricted area 90 where a safety sensor 1 according to the first embodiment of the present invention is provided. The restricted area 90 is, for example, a part of a factory area. The restricted area 90 is partitioned from the surroundings by a fence or a wall (hereinafter also referred to as "partition 91") and is an area where the entry of workers is restricted. An industrial machine 8 is installed in the restricted area 90, and workers enter when performing maintenance on the industrial machine 8.

[0018] An entrance / exit 92 is provided in the partition 91 surrounding the restricted area 90. The entrance / exit 92 is provided with a door 93 for opening and closing the entrance / exit 92. In other words, the restricted area 90 is surrounded by the partition 91, except for the entrance / exit 92 which is provided with a door 93. A safety sensor 1 is provided near the entrance / exit 92. The safety sensor 1 is an RFID (Radio Frequency Identification) type non-contact safety sensor. The safety sensor 1 is a device that detects the opening and closing of the door 93 and allows the industrial machine 8 to be driven only when the door 93 is closed. The safety sensor 1 is also called a safety switch or interlock device. In the example shown in Figure 1, the safety sensor 1 is located outside the restricted area 90. Note that the installation location of the safety sensor 1 can be changed in various ways. For example, the safety sensor 1 may be installed inside the restricted area 90.

[0019] Figure 2 is a plan view showing an enlarged view of the vicinity of the safety sensor 1. Figure 2 also shows other components besides the safety sensor 1. In Figure 2, the state in which the door 93 is slightly open is shown by a dashed line, and the state in which the door 93 is closed is shown by a solid line.

[0020] The safety sensor 1 comprises a sensor head 2 and an actuator 3. The sensor head 2 is fixed, for example, to a portion of the partition 91 near the side edge of the entrance / exit 92, outside the restricted area 90. The actuator 3 is fixed, for example, to a portion near the side edge of the door 93.

[0021] The actuator 3 includes an RFID tag 31. The RFID tag 31 is built into the main body of the actuator 3. The RFID tag 31 includes an antenna and an IC chip (not shown). As shown in Figure 3, the IC chip of the RFID tag 31 is provided with a tag memory area 34 for storing tag information. The tag memory area 34 includes a first tag memory area 35, a second tag memory area 36, ​​and a third tag memory area 37.

[0022] The first tag memory area 35 is pre-stored with a unique identifier (hereinafter also referred to as "unique ID 41") that uniquely identifies the RFID tag 31 of the actuator 3. The second tag memory area 36 is pre-stored with product information 42, which is information relating to the manufacturer and type of the safety sensor 1. The product information 42 includes, for example, the name of the manufacturer that produced the safety sensor 1 and the product model number of the safety sensor 1. The information included in the product information 42 may be changed in various ways. For example, the product information 42 may include information other than the manufacturer name and product model number (for example, the name of the manufacturing department). Also, the product information 42 does not necessarily have to include the manufacturer name and product model number.

[0023] The third tag memory area 37 pre-stores usage information 43 for the safety sensor 1. The usage information 43 indicates whether the safety sensor 1 is for high-code or low-code operation. High-code operation is a mode in which the unique ID 41 described above is used when the sensor head 2, described later, detects the actuator 3. Low-code operation is a mode in which the unique ID 41 is not used when the sensor head 2 detects the actuator 3. In other words, the usage information 43 indicates whether the actuator 3 is used in high-code or low-code operation.

[0024] Thus, in the safety sensor 1, the tag information stored in the tag memory area 34 includes a unique ID 41 specific to the actuator 3, product information 42 for the safety sensor 1, and application information 43 for the safety sensor 1.

[0025] The sensor head 2 comprises an RFID reader 21, an antenna 22, and a controller 23. The RFID reader 21, antenna 22, and controller 23 are built into the main body of the sensor head 2. The sensor head 2 is connected to a control device (not shown) of the industrial machine 8 via wiring 28. This control device includes, for example, a PLC (Programmable Logic Controller).

[0026] As described later, the RFID reader 21 reads the tag information stored in the RFID tag 31 of the actuator 3 and transmits the tag information to the controller 23. The memory section (not shown) of the IC chip of the controller 23 is provided with a sensor memory area 24 for storing sensor information, as shown in Figure 4. The sensor memory area 24 includes a first sensor memory area 25 and a second sensor memory area 26.

[0027] As described later, the unique ID 41 of the actuator 3 is written to the first sensor memory area 25 as a unique ID 51 as needed. The product information 52 of the safety sensor 1 is pre-stored in the second sensor memory area 26. That is, the sensor information stored in the sensor memory area 24 includes the product information 52 of the safety sensor 1. The product information 52 includes, for example, the name of the manufacturer that produced the safety sensor 1 and the product model number of the safety sensor 1. The information included in the product information 52 may be changed in various ways. For example, the product information 52 may include information other than the name of the manufacturer and the product model number (for example, the name of the manufacturing department). Also, the product information 52 does not necessarily have to include the name of the manufacturer and the product model number.

[0028] When the door 93 of the entrance / exit 92 is closed, the actuator 3 approaches the sensor head 2, as shown by the solid line in Figure 2. When the distance between the actuator 3 and the sensor head 2 becomes less than or equal to a predetermined communication range (for example, about 10 mm), wireless communication is performed between the antenna 22 of the sensor head 2 and the RFID tag 31 of the actuator 3. This communication information is transmitted to the controller 23 via the RFID reader 21, allowing the sensor head 2 to detect the actuator 3. The frequency used for this wireless communication is, for example, the HF (High Frequency) band.

[0029] When the sensor head 2 detects the actuator 3, it is determined that the door 93 is closed, and information enabling the industrial machine 8 to be driven is output from the controller 23 of the sensor head 2 to the control device of the industrial machine 8. In other words, the sensor head 2 performs an ON output process that turns on the safety output for the industrial machine 8. This enables power supply to the industrial machine 8. On the other hand, when the door 93 of the entrance / exit 92 is open and the sensor head 2 cannot detect the actuator 3 (i.e., the actuator 3 is farther away from the sensor head 2 than the communication range), the safety output output from the controller 23 of the sensor head 2 is OFF, and power cannot be supplied to the industrial machine 8.

[0030] Next, we will explain the operation examples of safety sensor 1 with reference to Figures 5 through 8B. Below, we will first explain the operation example of safety sensor 1 for low-code systems with reference to Figure 5, and then explain the operation example of safety sensor 1 for high-code systems.

[0031] In the low-code safety sensor 1, the application information 43 stored in the third tag memory area 37 of the actuator 3 is "low-code". Also, no information such as a unique ID 51 is written to the first sensor memory area 25 of the sensor head 2, and the first sensor memory area 25 is blank.

[0032] In the example shown in Figure 5, when the power to the safety sensor 1 is first turned ON, the first sensor memory area 25 is checked in the sensor head 2. If it is confirmed that the first sensor memory area 25 is blank (step S11), the operations from step S12 onwards are performed. Note that if a unique ID 51 is stored in the first sensor memory area 25 in step S11, the safety sensor 1 is for high-code use, and the operations described later in Figures 6A and 6B are performed.

[0033] When step S11 is completed, the sensor head 2 begins searching for the actuator 3. When the aforementioned door 93 is closed from its open state, wireless communication is performed between the antenna 22 of the sensor head 2 and the RFID tag 31 of the actuator 3, and the RFID tag 31 of the actuator 3 is detected. Then, the RFID reader 21 of the sensor head 2 reads the product information 42 stored in the second tag memory area 36 of the RFID tag 31 of the actuator 3 and transmits it to the controller 23 (step S12). The sensor head 2 compares the product information 42 of the RFID tag 31 read by the RFID reader 21 and transmitted to the controller 23 with the product information 52 that is pre-stored in the memory section (not shown) of the controller 23, and confirms whether the product information 42 and the product information 52 match (step S13).

[0034] In step S13, product information 42 and product information 52 may be judged to be a match only if they are a perfect match. Alternatively, product information 42 and product information 52 may be judged to be a match if a predetermined part of product information 42 and product information 52 (for example, the manufacturer's name) matches according to a predetermined rule. In other words, the criterion for determining whether product information 42 and product information 52 are a match in step S13 may be set to either a perfect match or a partial match. Note that if the RFID reader 21 is unable to read the product information 42 of the RFID tag 31 in step S12, then in step S13, product information 42 and product information 52 are judged not to be a match (i.e., they are mismatched).

[0035] If product information 42 and product information 52 match in step S13, the processing from step S14 onwards is performed. On the other hand, if product information 42 and product information 52 do not match in step S13, it is determined that an error has occurred in safety sensor 1 and error processing is performed (step S17). Specifically, for example, safety sensor 1 is locked out and requires a restart, and the operation of safety sensor 1 is terminated. This error processing is performed, for example, when an actuator from another company whose product information is not stored is brought close to sensor head 2.

[0036] In step S13, if it is determined that product information 42 and product information 52 match, the RFID reader 21 of the sensor head 2 reads the application information 43 stored in the third tag memory area 37 of the RFID tag 31 of the actuator 3 (i.e., the application information 43 is read and acquired) (step S14).

[0037] If the usage information 43 read by the RFID reader 21 is "low code" (step S15), the controller 23 performs an ON output process to turn on the safety output to the industrial machine 8 (step S16). This ON output process is called the "authorized process," and in the safety sensor 1, the authorized process (i.e., the ON output process) in the sensor head 2 is only executed if the product information 42 of the RFID tag 31 read by the RFID reader 21 matches the product information 52 pre-stored in the memory of the controller 23. This prevents or suppresses malfunctions or intentional deactivation of the safety sensor 1 by RFID tags of items other than the actuator 3 of the safety sensor 1 (for example, transportation IC cards, etc.).

[0038] When the door 93 is closed, the ON output from the safety sensor 1 continues. When the door 93 is opened and wireless communication between the sensor head 2 and the actuator 3 stops, the sensor head 2 performs an OFF output process to turn off the safety output to the industrial machine 8.

[0039] On the other hand, if the usage information 43 read by the RFID reader 21 is "high code" and not "low code" (step S15), the initial teaching process described later in Figures 7A and 7B is performed. If the usage information 43 read by the RFID reader 21 is neither "low code" nor "high code," or if the usage information 43 cannot be read, the safety sensor 1 determines that an error has occurred and the above-mentioned error processing is performed.

[0040] Next, an example of the operation of the safety sensor 1 for Hi-Code will be explained with reference to Figures 6A and 6B. In the safety sensor 1 for Hi-Code, the application information 43 stored in the third tag memory area 37 of the actuator 3 is "Hi-Code". In addition, the unique ID 41 of the actuator 3, which is associated with the sensor head 2 in a one-to-one relationship, is pre-written in the first sensor memory area 25 of the sensor head 2 and stored as unique ID 51.

[0041] In the example shown in Figures 6A and 6B, when the power to the safety sensor 1 is turned ON, the first sensor memory area 25 is checked in the sensor head 2. If it is confirmed that the unique ID 51 is stored in the first sensor memory area 25 (step S21), the operations from step S22 onward are performed. Note that if the first sensor memory area 25 is blank in step S21, the safety sensor 1 is for low-code use, and the operation illustrated in Figure 5 described above is performed.

[0042] Once step S21 is completed, steps S22 to S24, which are essentially the same as steps S12 to S14 described above, are performed. Specifically, the sensor head 2 detects the RFID tag 31 of the actuator 3, and the RFID reader 21 reads the product information 42 stored in the second tag memory area 36 of the RFID tag 31 (step S22). Then, the product information 42 of the RFID tag 31, which has been read by the RFID reader 21 and transmitted to the controller 23, is compared with the product information 52 that is pre-stored in the memory section of the controller 23, and it is confirmed whether the product information 42 and the product information 52 match (step S23).

[0043] If product information 42 and product information 52 match in step S23, the processing from step S24 onwards is carried out. On the other hand, if product information 42 and product information 52 do not match in step S23, it is determined that an error has occurred in safety sensor 1, and error processing is carried out in much the same manner as in step S17 above (step S29).

[0044] If it is determined in step S23 that product information 42 and product information 52 match, the RFID reader 21 reads the usage information 43 stored in the third tag memory area 37 of the RFID tag 31 (i.e., the usage information 43 is read and acquired) (step S24).

[0045] If the usage information 43 read by the RFID reader 21 is not "high code" (step S25), the safety sensor 1 determines that an error has occurred and performs error processing (step S29). Specifically, for example, the safety sensor 1 is locked out and requires a restart, and the operation of the safety sensor 1 is terminated. This error processing is performed, for example, when a low-code actuator 3 is brought close to the sensor head 2, or when an actuator from another company that does not have product information stored in it is brought close to the sensor head 2. Alternatively, if a low-code actuator 3 is detected, the detection result of this low-code actuator 3 may be ignored, and the safety sensor 1 may not be locked out, continuing normal operations such as tag searching.

[0046] On the other hand, if the usage information 43 read by the RFID reader 21 is a "high code" (step S25), the RFID reader 21 reads the unique ID 41 stored in the first tag memory area 34 of the RFID tag 31 (step S26). Then, the unique ID 41 of the RFID tag 31 read by the RFID reader 21 and transmitted to the controller 23 is compared with the unique ID 51 that is pre-stored in the memory section of the controller 23 to confirm whether the unique ID 41 and the unique ID 51 match (step S27).

[0047] If unique ID 41 and unique ID 51 match in step S27, the controller 23 performs an ON output process to turn on the safety output for the industrial machine 8 (step S28). On the other hand, if unique ID 41 and unique ID 51 do not match in step S27, the above-described error processing is performed (step S29). This error processing is performed, for example, when an actuator 3 of the same type but different from the actuator 3 that is pre-associated one-to-one with the sensor head 2 is brought close to the sensor head 2. As will be described later, by performing a predetermined operation between step S27 and step S29, error processing may be omitted and re-teaching processing (see Figures 8A and 8B) may be performed.

[0048] Thus, in the Hi-Code safety sensor 1, the RFID reader 21 reads the unique ID 41 of the RFID tag 31 only if the product information 42 of the RFID tag 31, read by the RFID reader 21 and transmitted to the controller 23, matches the product information 52 pre-stored in the memory of the controller 23. Furthermore, the ON output process (i.e., authorized process) in the sensor head 2 is only executed if the unique ID 41 of the RFID tag 31, read by the RFID reader 21 and transmitted to the controller 23, matches the unique ID 51 pre-stored in the memory of the controller 23.

[0049] As a result, if an RFID tag of an item different from the actuator 3 of the safety sensor 1 (for example, a transportation IC card) is brought close to the sensor head 2, error processing can be performed without reading the unique ID of the RFID tag. Furthermore, even if another actuator of the same type as the actuator 3 of the safety sensor 1 is brought close to the sensor head 2, malfunction of the safety sensor 1 due to the RFID tag of the other actuator (i.e., false detection of the other actuator) and intentional deactivation of the safety sensor 1 are prevented or suppressed.

[0050] When the door 93 is closed, the ON output from the safety sensor 1 continues. When the door 93 is opened and wireless communication between the sensor head 2 and the actuator 3 stops, the sensor head 2 performs an OFF output process to turn off the safety output to the industrial machine 8.

[0051] Next, the flow of the initial teaching process for safety sensor 1 to be used as a high-code safety sensor 1 will be explained with reference to Figures 7A and 7B. A high-code safety sensor 1 refers to a sensor head 2 in which a unique ID 51 has been written to the first sensor memory area 25. The initial teaching process is performed when safety sensor 1 is attached to a partition 91 and a door 93 (see Figure 1) and put into use. The initial teaching process is the process of writing the unique ID 41 of the actuator 3 that corresponds one-to-one with the sensor head 2 to the blank first sensor memory area 25 of the sensor head 2 of safety sensor 1. The initial teaching process is also called the pairing process.

[0052] As described above, the initial teaching process is initiated when steps S11 to S15 are performed, and in step S11 the first sensor memory area 25 is blank, and in step S15 the usage information 43 of the RFID tag 31 is "high code". When the initial teaching process is initiated, the safety sensor 1 notifies the user that the initial teaching process has started, for example, by lighting up an indicator (not shown) provided on the sensor head 2.

[0053] In the examples shown in Figures 7A and 7B, once the initial teaching process begins, the elapsed time from the start is continuously measured by the controller 23 of the sensor head 2. Then, at a predetermined timing, the door 93 is opened and closed again, causing the unique ID 41 of the RFID tag 31 to be written as a unique ID 51 to the first sensor memory area 25 of the sensor head 2.

[0054] Specifically, when the initial teaching process begins with the door 93 closed, the RFID reader 21 of the sensor head 2 reads the tag information from the RFID tag 31. However, this reading of the tag information must only continue within a predetermined first time condition. This first time condition is, for example, 5 seconds or more and less than 10 seconds. In this case, the door 93 must remain closed for 5 seconds or more from the start of the initial teaching process to continue reading the tag information, and the door 93 must be opened before 10 seconds have elapsed from the start of the initial teaching process to prevent the RFID reader 21 from reading the tag information.

[0055] In other words, the initial teaching process continues only if the duration of reading the tag information of the RFID tag 31 by the RFID reader 21 is within the range of the first time condition (for example, 5 seconds or more and less than 10 seconds) (step S31). In the sensor head 2, the unique ID 41 included in the tag information read by the RFID reader 21 is temporarily held (stored) in the cache memory (not shown) of the controller 23 as a provisional unique identifier (hereinafter also referred to as "provisional unique ID") (step S32).

[0056] On the other hand, if the duration of reading the tag information of the RFID tag 31 by the RFID reader 21 is outside the range of the first time condition, it is determined that an error has occurred in the initial teaching process and error processing is performed (step S40). Specifically, if the door 93 is opened before 5 seconds have elapsed since the start of the initial teaching process, and if the door 93 remains closed even after 10 seconds have elapsed since the start of the initial teaching process, error processing is performed. In error processing, for example, the safety sensor 1 is locked out and requires a restart, and the initial teaching process ends in a failed state. The sensor head 2 may notify the elapsed time since the start of the initial teaching process by changing the blinking interval of the indicator mentioned above.

[0057] In the initial teaching process, following steps S31 to S32, the door 93 must remain open for a predetermined second time period, making it impossible for the RFID reader 21 to read the tag information. After this, the door 93 must be closed, making it possible to read the tag information. This allows the initial teaching process to continue. The second time period is, for example, 1 second or more and less than 5 seconds. In this case, the door 93 must remain open for at least 1 second after the end of steps S31 to S32 (i.e., the opening of the door 93) to continue the state in which the tag information cannot be read, and the door 93 must be closed before 5 seconds have elapsed since the end of steps S31 to S32, making it possible for the RFID reader 21 to read the tag information.

[0058] In other words, in the initial teaching process, following steps S31 to S32, the initial teaching process continues only if the RFID reader 21 remains unable to read the tag information within the range of the second time condition (step S33). To put it another way, the initial teaching process continues only if the duration of the RFID reader 21's inability to read the tag information is within the range of the second time condition.

[0059] On the other hand, if the duration of the state in which the RFID reader 21 is unable to read the tag information is outside the range of the second time condition, it is determined that an error has occurred in the initial teaching process and the above-described error processing is performed (step S40). Specifically, the above-described error processing is performed if the door 93 is closed before 1 second has elapsed since the end of steps S31 to S32 (i.e., the door 93 is opened), and if the door 93 remains open even after 5 seconds have elapsed since the end of steps S31 to S32. The sensor head 2 may notify the elapsed time since the end of steps S31 to S32 by changing the blinking interval of the indicator mentioned above.

[0060] If the initial teaching process continues in step S33, the RFID reader 21 of the sensor head 2 reads the tag information of the RFID tag 31 (step S34). The sensor head 2 compares the product information 42 contained in the tag information with the product information 52 contained in the sensor information stored in the memory of the controller 23 (step S35). If the product information 42 contained in the tag information and the product information 52 contained in the sensor information match, the initial teaching process continues. On the other hand, if the product information 42 contained in the tag information and the product information 52 contained in the sensor information do not match, the error processing described above is performed (step S40).

[0061] If the initial teaching process continues in step S35, the sensor head 2 checks the usage information 43 included in the tag information (step S36). If the usage information 43 is "high code", the initial teaching process continues. On the other hand, if the usage information 43 is "low code" or if the usage information 43 cannot be read, the above-mentioned error processing is performed (step S40).

[0062] If the initial teaching process continues in step S36, the sensor head 2 compares the unique ID 41 included in the tag information with the temporary unique ID stored in the controller 23's cache memory (step S37). If the unique ID 41 included in the tag information matches the temporary unique ID, the initial teaching process continues. On the other hand, if the unique ID 41 and the temporary unique ID do not match, the error processing described above is performed (step S40).

[0063] If the initial teaching process continues in step S37, after a predetermined write waiting time (for example, 5 seconds) has elapsed with the door 93 closed since the end of step S33 (i.e., the closing of the door 93) (step S38), the aforementioned temporary unique ID is written to and stored in the first sensor memory area 25 of the controller 23 as the unique ID 51 of the sensor information (step S39). This completes the initial teaching process of the safety sensor 1.

[0064] If we refer to this initial teaching process as the "authorized process," then in the safety sensor 1, the authorized process (i.e., the initial teaching process) can only be executed if the product information 42 of the RFID tag 31 read by the RFID reader 21 matches the product information 52 pre-stored in the memory of the controller 23. This prevents or suppresses malfunctions or intentional deactivation of the safety sensor 1 by RFID tags of items other than the actuator 3 of the safety sensor 1 (for example, transportation IC cards).

[0065] Once the initial teaching process for safety sensor 1 is complete, an ON output process is performed by safety sensor 1 for high code, as shown in Figures 6A and 6B. The sensor head 2 may notify the elapsed time of the write waiting period in step S38 by changing the blinking interval of the indicator mentioned above.

[0066] In step S39, it can also be understood that the unique ID 41 of the actuator 3, which was read by the RFID reader 21 in step S34, is included in the sensor information as the unique ID 51 mentioned above. Furthermore, if the door 93 is opened in step S38 before the aforementioned write waiting time has elapsed, the aforementioned error processing is performed.

[0067] In this way, by complicating the initial teaching procedure, the safety sensor 1 can prevent or deter the execution of the initial teaching process by persons who do not have the authority to perform the initial teaching process (i.e., persons who do not have the authority to access the safety sensor 1 manual). Furthermore, it can weaken the will of those who attempt to perform the initial teaching process illegally. As a result, it is possible to prevent or deter the intentional deactivation of the safety sensor 1.

[0068] The first and second time conditions described above may be the same or different. Furthermore, the first and second time conditions may be modified in various ways. For example, the first time condition may consist of only one of the two time limits (5 seconds or more in the example above) and the other (less than 10 seconds in the example above). The same applies to the second time condition.

[0069] Next, the reteaching process for the Hi-Code safety sensor 1 will be explained with reference to Figures 8A and 8B. The reteaching process is performed when replacing the actuator 3 in the Hi-Code safety sensor 1 that was being used due to loss or malfunction. The reteaching process involves writing the unique ID 41 of the new actuator 3, which corresponds one-to-one with the sensor head 2, to the first sensor memory area 25 in the Hi-Code safety sensor 1 where the unique ID 51 is already stored, thereby overwriting (i.e., rewriting) the unique ID 51 contained in the sensor information.

[0070] As described above, the reteaching process is performed when, during steps S21 to S29, a unique ID 51 is stored in the first sensor memory area 25 in step S21, and in step S27, the unique ID 51 does not match the unique ID 41 of the actuator 3 (i.e., they are mismatched). The reteaching process is started when the user performs a predetermined action between steps S27 and S29. In the following description, this predetermined action will also be included in the reteaching process. If this predetermined action is not performed, the reteaching process cannot be executed, and the error processing described above (step S29) is performed.

[0071] In the examples shown in Figures 8A and 8B, if a mismatch in the unique ID is detected in step S27, the elapsed time from the time of detection is continuously measured by the controller 23 of the sensor head 2. Then, at a predetermined timing, the door 93 is opened and closed again, thereby performing a re-teaching process.

[0072] Specifically, first, when a mismatch in the unique ID is detected while the door 93 is closed, the RFID reader 21 of the sensor head 2 reads the tag information from the RFID tag 31. However, this reading of the tag information must only continue within a predetermined third time condition. This third time condition is, for example, 5 seconds or more and less than 10 seconds. In this case, the door 93 must remain closed for at least 5 seconds after the unique ID mismatch is detected, allowing the reading of the tag information to continue. The door 93 must then be opened before 10 seconds have elapsed since the unique ID mismatch was detected, making it impossible for the RFID reader 21 to read the tag information.

[0073] In other words, the re-teaching process continues only if the duration of reading the tag information of the RFID tag 31 by the RFID reader 21 is within the range of the third time condition (for example, 5 seconds or more and less than 10 seconds) (step S51).

[0074] On the other hand, if the duration of reading the tag information of the RFID tag 31 by the RFID reader 21 is outside the range of the third time condition, it is determined that an error has occurred in the reteaching process and error processing is performed (step S62). Specifically, if the door 93 is opened before 5 seconds have elapsed since the unique ID mismatch was discovered, and if the door 93 remains closed even after 10 seconds have elapsed since the unique ID mismatch was discovered, error processing is performed. In error processing, for example, the safety sensor 1 is locked out and requires a restart, and the reteaching process ends in a failed state. The sensor head 2 may notify the elapsed time since the unique ID mismatch was discovered by changing the blinking interval of the indicator mentioned above.

[0075] In the re-teaching process, following step S51, the door 93 must remain open for a predetermined fourth time period, making it impossible for the RFID reader 21 to read the tag information. After this, the door 93 must be closed, making it possible to read the tag information. This allows the re-teaching process to continue. The fourth time period is, for example, 1 second or more and less than 5 seconds. In this case, the door 93 must remain open for at least 1 second after the end of step S51 (i.e., the door 93 is opened), continuing the state in which the tag information cannot be read, and the door 93 must be closed before 5 seconds have elapsed since the end of step S51, making it possible for the RFID reader 21 to read the tag information.

[0076] In other words, in the re-teaching process, following step S51, the re-teaching process continues only if the state in which the RFID reader 21 is unable to read the tag information continues within the range of the fourth time condition (step S52). To put it another way, the re-teaching process continues only if the duration of the state in which the RFID reader 21 is unable to read the tag information is within the range of the fourth time condition.

[0077] On the other hand, if the duration of the state in which the RFID reader 21 is unable to read the tag information is outside the range of the fourth time condition, it is determined that an error has occurred in the initial teaching process and the above-described error processing is performed (step S62). Specifically, the above-described error processing is performed if the door 93 is closed before 1 second has elapsed since the end of step S51 (i.e., the door 93 is opened), and if the door 93 remains open even after 5 seconds have elapsed since the end of step S51. The sensor head 2 may notify the elapsed time since the end of step S51 by changing the blinking interval of the indicator mentioned above.

[0078] Once step S52 is completed, the door 93 is opened and then closed again at a predetermined timing, similar to steps S31 to S39 described above (see Figures 7A and 7B), and the unique ID 41 of the RFID tag 31 is written as the unique ID 51 to the first sensor memory area 25 of the sensor head 2 (steps S53 to S61).

[0079] Specifically, first, with the door 93 closed, the RFID reader 21 of the sensor head 2 reads the tag information of the RFID tag 31. This reading of the tag information must continue only within a predetermined fifth time condition. This fifth time condition is, for example, 5 seconds or more and less than 10 seconds. In this case, the door 93 must remain closed for 5 seconds or more from the end of step S52 (i.e., the door 93 is closed) to continue reading the tag information, and the door 93 must be opened before 10 seconds have elapsed from the end of step S52 to prevent the RFID reader 21 from reading the tag information.

[0080] In other words, the reteaching process continues only if the duration of reading the tag information of the RFID tag 31 by the RFID reader 21 is within the range of the fifth time condition (for example, 5 seconds or more and less than 10 seconds) (step S53). In the sensor head 2, the unique ID 41 included in the tag information read by the RFID reader 21 is temporarily held (stored) in the above cache memory of the controller 23 as a provisional unique identifier (i.e., provisional unique ID) (step S54).

[0081] If the duration of reading the tag information of the RFID tag 31 by the RFID reader 21 is outside the range of the fifth time condition, it is determined that an error has occurred during the re-teaching process and error processing is performed (step S62). Specifically, if the door 93 is opened before 5 seconds have elapsed since the end of step S52, and if the door 93 remains closed even after 10 seconds have elapsed since the end of step S52, error processing is performed. In error processing, for example, the safety sensor 1 is locked out and requires a restart, and the re-teaching process ends in a failed state. The sensor head 2 may notify the elapsed time since the end of step S52 by changing the blinking interval of the indicator mentioned above.

[0082] In the re-teaching process, following steps S53 to S54, the door 93 must remain open for a predetermined sixth time condition, making it impossible for the RFID reader 21 to read the tag information. After this, the door 93 must be closed, making it possible to read the tag information. This allows the re-teaching process to continue. The sixth time condition is, for example, 1 second or more and less than 5 seconds. In this case, the door 93 must remain open for at least 1 second after the end of steps S53 to S54 (i.e., the door 93 is opened), continuing the state in which the tag information cannot be read. The door 93 must then be closed before 5 seconds have elapsed since the end of steps S53 to S54, making it possible for the RFID reader 21 to read the tag information.

[0083] In other words, in the re-teaching process, following steps S53 to S54, the re-teaching process continues only if the state in which the RFID reader 21 is unable to read the tag information continues within the range of the sixth time condition (step S55). To put it another way, the re-teaching process continues only if the duration of the state in which the RFID reader 21 is unable to read the tag information is within the range of the sixth time condition.

[0084] On the other hand, if the duration of the state in which the RFID reader 21 is unable to read the tag information is outside the range of the sixth time condition, it is determined that an error has occurred in the re-teaching process and the above-described error processing is performed (step S62). Specifically, the above-described error processing is performed if the door 93 is closed before 1 second has elapsed since the end of steps S53 to S54 (i.e., the door 93 is opened), and if the door 93 remains open even after 5 seconds have elapsed since the end of steps S53 to S54. The sensor head 2 may notify the elapsed time since the end of steps S53 to S54 by changing the blinking interval of the indicator mentioned above.

[0085] When step S55 is completed, the RFID reader 21 of the sensor head 2 reads the tag information of the RFID tag 31 (step S56). The sensor head 2 compares the product information 42 contained in the tag information with the product information 52 contained in the sensor information stored in the memory of the controller 23 (step S57). If the product information 42 contained in the tag information and the product information 52 contained in the sensor information match, the re-teaching process continues. On the other hand, if the product information 42 contained in the tag information and the product information 52 contained in the sensor information do not match, the error processing described above is performed (step S62).

[0086] If the re-teaching process continues in step S57, the sensor head 2 checks the usage information 43 included in the tag information (step S58). If the usage information 43 is "high code", the re-teaching process continues. On the other hand, if the usage information 43 is "low code" or if the usage information 43 cannot be read, the above-mentioned error processing is performed (step S62).

[0087] If the re-teaching process continues in step S58, the sensor head 2 compares the unique ID 41 included in the tag information with the temporary unique ID stored in the controller 23's cache memory (step S59). If the unique ID 41 included in the tag information matches the temporary unique ID, the re-teaching process continues. On the other hand, if the unique ID 41 and the temporary unique ID do not match, the error processing described above is performed (step S62).

[0088] If the re-teaching process continues in step S59, after a predetermined write waiting time (for example, 5 seconds) has elapsed with the door 93 closed since the end of step S55 (i.e., the closing of the door 93) (step S60), the aforementioned temporary unique ID is written to and stored in the first sensor memory area 25 of the controller 23 as the unique ID 51 of the sensor information (step S61). In step S61, the unique ID 51 that was stored in the first sensor memory area 25 before step S61 is overwritten by the aforementioned temporary unique ID. This completes the re-teaching process of the safety sensor 1.

[0089] If we refer to this re-teaching process as an "authorized process," then in the safety sensor 1, the authorized process (i.e., the re-teaching process) can only be executed if the product information 42 of the RFID tag 31 read by the RFID reader 21 matches the product information 52 pre-stored in the memory of the controller 23. This prevents or suppresses malfunctions or intentional deactivation of the safety sensor 1 by RFID tags of items other than the actuator 3 of the safety sensor 1 (for example, transportation IC cards).

[0090] Once the re-teaching process for safety sensor 1 is complete, steps S21 to S28 shown in Figures 6A and 6B are performed, and the safety sensor 1 for high code performs an ON output process. The sensor head 2 may notify the elapsed time of the write waiting period in step S60 by changing the blinking interval of the indicator mentioned above.

[0091] In step S61, it can also be understood that the unique ID 41 of the actuator 3, which was read by the RFID reader 21 in step S56, is included in the sensor information as the unique ID 51 mentioned above. Furthermore, if the door 93 is opened in step S60 before the aforementioned write waiting time has elapsed, the aforementioned error processing is performed.

[0092] In this way, by complicating the reteaching procedure, the safety sensor 1 can prevent or deter the reteaching process from being performed by persons who do not have the authority to perform the reteaching process (i.e., persons who do not have the authority to access the safety sensor 1 manual). Furthermore, it can weaken the will of those who attempt to perform the reteaching process illegally. As a result, the intentional deactivation of the safety sensor 1 can be prevented or deterred.

[0093] Furthermore, the third and fourth time conditions described above may be the same or different from each other. Also, the third and fourth time conditions may be modified in various ways. For example, the third time condition may consist of only one of the two time limits (5 seconds or more in the above example) and the other (less than 10 seconds in the above example). The same applies to the fourth time condition.

[0094] The fifth and sixth time conditions described above may be the same or different from each other. Furthermore, the fifth and sixth time conditions may be modified in various ways. For example, the fifth time condition may be defined by specifying only one of the two limits: a lower limit (5 seconds or more in the above example) and an upper limit (less than 10 seconds in the above example), while leaving the other limit unspecified. The same applies to the sixth time condition.

[0095] As described above, the safety sensor 1 comprises an actuator 3 and a sensor head 2. The actuator 3 has an RFID tag 31. The sensor head 2 has an RFID reader 21 and a memory unit. The RFID reader 21 reads the tag information stored in the RFID tag 31 when the actuator 3 is in close proximity. The memory unit stores the sensor information. The tag information and sensor information each include product information 42 and 52 of the safety sensor 1. Only when the product information 42 contained in the tag information read by the RFID reader 21 matches the product information 52 contained in the sensor information is authorized processing in the sensor head 2 (in the above example, ON output processing, initial teaching processing, or re-teaching processing) possible. This makes it possible to suppress false detection of the actuator 3 and intentional deactivation of the safety sensor 1, as described above.

[0096] In the example above, the tag information includes a unique identifier specific to actuator 3 (i.e., unique ID 41). The sensor head 2 determines whether the safety sensor 1 is used in high-code mode using unique ID 41 or low-code mode without unique ID 41. Greater effectiveness can be achieved if the above authorized process is an initial teaching process that stores unique ID 41 in the sensor head 2 and includes it in the sensor information, which is only executable when the usage information 43 is high-code.

[0097] In safety sensor 1, as described above, after confirming the match of product information 42 and 52, the unique ID 41 is read and written to controller 23. Therefore, if the initial teaching process is started using an item different from the actuator 3 that is to be associated with sensor head 2, the initial teaching process can be quickly stopped without performing operations such as reading the unique ID 41 and writing to controller 23. In other words, safety sensor 1 can quickly stop incorrect and fraudulent initial teaching processes.

[0098] As described above, the initial teaching process preferably includes the steps (S31-S32) in which the unique ID 41 included in the tag information is stored in the sensor head 2 as a temporary unique ID and the initial teaching process continues only if the duration of reading the tag information of the RFID tag 31 by the RFID reader 21 is within the range of a first time condition; the step (S33) in which the initial teaching process continues only if the state of being unable to read the tag information of the RFID tag 31 by the RFID reader 21 continues within the range of a second time condition, following steps S31-S32; and the step (S34, S35, S37, S39) in which the unique ID 41 included in the tag information is included in the sensor information only if the tag information of the RFID tag 31 is read by the RFID reader 21, the product information 42 included in the tag information matches the product information 52 included in the sensor information, and the unique ID 41 included in the tag information matches the temporary unique ID stored in the sensor head 2. In this way, by complicating the initial teaching process, it is possible to prevent or suppress the intentional disabling of the safety sensor 1.

[0099] In the above example, in the safety sensor 1, after the initial teaching process is completed, the re-teaching process in the sensor head 2 is only possible if the product information 42 contained in the tag information read by the RFID reader 21 matches the product information 52 contained in the sensor information, the application information 43 is a high code, and the unique ID 41 contained in the tag information read by the RFID reader 21 does not match the unique ID 51 contained in the sensor information.

[0100] The reteaching process preferably includes the steps of: continuing the reteaching process only if the duration of reading the tag information of the RFID tag 31 by the RFID reader 21 is within the range of the third time condition (step S51); continuing the reteaching process only if the state of being unable to read the tag information of the RFID tag 31 by the RFID reader 21 continues within the range of the fourth time condition (step S52); and continuing the reteaching process only if the RFID reader 21 reads the tag information of the RFID tag 31 and the duration of reading the tag information is within the range of the fifth time condition, and the unique ID 41 included in the tag information is stored in the sensor head 2 as a temporary unique ID. The process includes steps S53 to S54, a step S55 in which the reteaching process continues only if the RFID reader 21 remains unable to read the tag information of the RFID tag 31 within the range of the sixth time condition following steps S53 to S54, and a step S56, S57, S59, S61 in which the unique ID 51 included in the sensor information is rewritten to the unique ID 41 included in the tag information only if the RFID reader 21 reads the tag information of the RFID tag 31, the product information 42 included in the tag information matches the product information 52 included in the sensor information, and the unique ID 41 included in the tag information matches the temporary unique ID stored in the sensor head. By complicating the reteaching process in this way, it is possible to prevent or suppress the intentional deactivation of the safety sensor 1.

[0101] As described above, the frequency band used for wireless communication between the RFID reader 21 and the RFID tag 31 is preferably the HF band. Since the HF band is a widely used frequency band in RFID, the RFID reader 21 and RFID tag 31 can be easily obtained. Furthermore, even in the HF band, where many products are used, the safety sensor 1 can prevent or suppress misuse or intentional deactivation, as described above.

[0102] Next, a safety sensor 1a according to a second embodiment of the present invention will be described with reference to Figure 9. The safety sensor 1a has substantially the same configuration as the safety sensor 1 shown in Figure 2, and stores substantially the same information, except that a sensor head 2a is provided instead of the sensor head 2, and that the actuator 3 does not store application information 43 (see Figure 3). The sensor head 2a has the same structure as the sensor head 2, except that it is provided with terminal 29. In the following description, the same reference numerals are used for the components and stored information of the safety sensor 1a as for those of the safety sensor 1.

[0103] In the safety sensor 1a, the intended use of the safety sensor 1a is determined by a signal input to a predetermined terminal 29 of the sensor head 2a. As described above, this intended use information indicates whether the safety sensor 1a is for high-code or low-code use. The signal input to terminal 29 is, for example, a voltage. Specifically, if terminal 29 is electrically connected to a power supply and a voltage is applied to terminal 29, the safety sensor 1a is used for high-code use. On the other hand, if terminal 29 is not connected to a power supply and no voltage is applied to terminal 29, the safety sensor 1a is used for low-code use.

[0104] In safety sensor 1a, the signal input to terminal 29 may be anything other than voltage. For example, terminal 29 may be connected to a control device via a changeover switch. In this case, for example, the signal input from the control device to terminal 29 can be switched by the changeover switch between a signal indicating a high code and a signal indicating a low code.

[0105] When safety sensor 1a is used for low-code applications, the operation of safety sensor 1a is substantially the same as steps S11 to S17 shown in Figure 5, except that the source of application information acquisition in step S14 is different. In safety sensor 1a, the acquisition of application information in step S14 is not based on the RFID tag 31 of actuator 3, but on the signal input to terminal 29, as described above. In safety sensor 1a, as with safety sensor 1 described above, false detection by actuator 3 and intentional deactivation of safety sensor 1a can be suppressed.

[0106] When safety sensor 1a is used for Hi-Code, the operation of safety sensor 1a is substantially the same as steps S21 to S29 shown in Figures 6A and 6B, except that the source of acquisition of application information in step S24 is different. In safety sensor 1a, the acquisition of application information in step S24 is based on the signal input to terminal 29, not the RFID tag 31 of actuator 3. In safety sensor 1a, as with safety sensor 1 described above, false detection by actuator 3 and intentional deactivation of safety sensor 1a can be suppressed.

[0107] When the initial teaching process for safety sensor 1a is performed, the operation of safety sensor 1a is substantially the same as steps S31 to S39 shown in Figures 7A and 7B, except that the source of the application information from the tag information in step S34 is different. In safety sensor 1a, the application information is acquired based on the signal input to terminal 29 in parallel with the reading of the tag information in step S34. In safety sensor 1a, as with safety sensor 1 described above, intentional deactivation of safety sensor 1a can be prevented or suppressed by complicating the initial teaching process procedure.

[0108] When the safety sensor 1a undergoes reteaching, the operation of the safety sensor 1a is substantially the same as steps S51 to S62 shown in Figures 8A and 8B, except that the source of the application information from the tag information in step S56 is different. In the safety sensor 1a, the application information is acquired based on the signal input to terminal 29 in parallel with the reading of the tag information in step S56. In the safety sensor 1a as well, similar to the safety sensor 1 described above, intentional deactivation of the safety sensor 1a can be prevented or suppressed by complicating the reteaching procedure.

[0109] As described above, in the safety sensor 1a, the application information is determined based on the signal input to a predetermined terminal 29 provided on the sensor head 2a. As a result, whether the safety sensor 1a is used with low code or high code, there is no need to store the application information 43 in the actuator 3, and one actuator 3 can be used in common with both the low code and high code versions of the safety sensor 1a.

[0110] Various modifications are possible for the safety sensors 1 and 1a described above.

[0111] For example, in the operation of the low-code safety sensor 1 shown in Figure 5, the reading of the product information 42 of the RFID tag 31 and the confirmation of the match between the product information 42 of the RFID tag 31 and the product information 52 of the sensor head 2 (steps S12-S13) may be performed after the reading and confirmation of the application information 43 (steps S14-S15).

[0112] In the operation of the Hi-Code safety sensor 1 shown in Figures 6A and 6B, the reading of the product information 42 of the RFID tag 31 and the confirmation of the match between the product information 42 of the RFID tag 31 and the product information 52 of the sensor head 2 (steps S22-S23) may be performed after the reading and confirmation of the application information 43 (steps S24-S25), and may also be performed after the reading of the unique ID 41 and the confirmation of the match between the unique ID 41 of the RFID tag 31 and the unique ID 51 stored in the sensor head 2 (steps S26-S27).

[0113] In the initial teaching process and re-teaching process described above, the method for determining whether to continue the process based on the opening and closing of door 93 can be varied. For example, the number of times door 93 is opened and closed, the time conditions described above, etc., can be varied. In addition, the decision on whether to continue the initial teaching process and re-teaching process may be made based on processes other than the opening and closing of door 93.

[0114] For example, in steps S31 and S33 described above, the initial teaching process is permitted to continue by switching the RFID tag 31 between readable and unreadable states according to predetermined rules by opening and closing the door 93, but it is not necessarily limited to this.

[0115] In steps S51 and S52 described above, the re-teaching process is permitted to continue by switching the RFID tag 31 between readable and unreadable states according to predetermined rules by opening and closing the door 93, but it is not necessarily limited to this.

[0116] In steps S53 and S55 described above, the re-teaching process is permitted to continue by switching the RFID tag 31 between readable and unreadable states according to predetermined rules by opening and closing the door 93, but it is not necessarily limited to this.

[0117] In the error handling described above, for example, in addition to locking out safety sensor 1, the surrounding area may be notified that safety sensor 1 has been intentionally disabled by illuminating a warning light or sounding an alarm. Alternatively, safety sensor 1 may send a monitor output to a higher-level PLC to notify that safety sensor 1 has been intentionally disabled.

[0118] In the safety sensor 1, for example, an RFID reader 21 and an RFID tag 31 that use the LF (Low Frequency) band for wireless communication may be used. The same applies to the safety sensor 1a.

[0119] In steps S32 and S54 described above, the provisional unique identifier was temporarily stored in the cache memory of the controller 23, but this is not limited to that. For example, the provisional unique identifier may be stored in the sensor memory area 24 of the controller 23.

[0120] In safety sensors 1,1a, the shape and structure of the sensor heads 2,2a and actuator 3 can be modified in various ways. For example, the sensor heads 2,2a may have two controllers 23 and two sensor memory areas 24, each duplicated to allow mutual monitoring of memory information. Alternatively, the memory portion of the sensor heads 2,2a may be an external memory located outside the IC chip. Furthermore, the object on which safety sensors 1,1a are installed is not limited to the above example and can be modified in various ways.

[0121] The configurations in the above embodiments and each modified example may be combined as appropriate, as long as they do not contradict each other. [Explanation of symbols]

[0122] 1,1a Safety Sensor 2,2a Sensor head 3 Actuators 21 RFID readers 29 terminals 31 RFID tags 41,51 unique IDs 42, 52 Product Information 43 Application information S11-S17, S21-S29, S31-S40, S51-S62 Step

Claims

1. It is a safety sensor, An actuator having an RFID tag, A sensor head having an RFID reader that reads tag information stored in the RFID tag when the actuator approaches, and a memory unit that stores sensor information, Equipped with, The tag information and the sensor information each include product information of the safety sensor, A safety sensor in which authorized processing in the sensor head can be executed only when the product information contained in the tag information read by the RFID reader matches the product information contained in the sensor information.

2. A safety sensor according to claim 1, The tag information includes a unique identifier specific to the actuator, The application information indicating whether the safety sensor is used with high-code or low-code without the unique identifier is determined by the sensor head. The aforementioned authorized processing is an initial teaching process in which the sensor head stores the unique identifier and includes it in the sensor information, which is only executable when the application information is high-coded, in a safety sensor.

3. A safety sensor according to claim 2, The aforementioned application information is determined based on a signal input to a predetermined terminal provided on the sensor head, and is a safety sensor.

4. A safety sensor according to claim 2, The initial teaching process described above is: a) If the duration of reading the tag information of the RFID tag by the RFID reader is within the range of the first time condition, the unique identifier included in the tag information is stored in the sensor head as a provisional unique identifier and the initial teaching process continues; b) Following step a), the initial teaching process is continued only if the RFID reader remains unable to read the tag information of the RFID tag within the range of the second time condition, c) After step b) above, the RFID reader reads the tag information of the RFID tag, and only if the product information contained in the tag information matches the product information contained in the sensor information, and the unique identifier contained in the tag information matches the temporary unique identifier stored in the sensor head, the unique identifier contained in the tag information is included in the sensor information. A safety sensor equipped with this feature.

5. A safety sensor according to claim 2, After the completion of the initial teaching process, the re-teaching process in the sensor head is only possible if the product information contained in the tag information read by the RFID reader matches the product information contained in the sensor information, the application information is high-coded, and the unique identifier contained in the tag information read by the RFID reader does not match the unique identifier contained in the sensor information. The aforementioned reteaching process is: d) The reteaching process is continued only if the duration of reading the tag information of the RFID tag by the RFID reader is within the range of the third time condition, e) Following step d), the re-teaching process is continued only if the RFID reader remains unable to read the tag information of the RFID tag within the range of the fourth time condition, f) Following step e) above, the RFID reader reads the tag information of the RFID tag, and only if the duration of reading the tag information is within the range of the fifth time condition, the unique identifier included in the tag information is stored in the sensor head as a provisional unique identifier and the reteaching process continues; g) Following step f), the re-teaching process is continued only if the RFID reader remains unable to read the tag information of the RFID tag within the range of the sixth time condition, h) After step g) above, if the RFID reader reads the tag information of the RFID tag, and the product information contained in the tag information matches the product information contained in the sensor information, and the unique identifier contained in the tag information matches the temporary unique identifier stored in the sensor head, then the unique identifier contained in the sensor information is rewritten to the unique identifier contained in the tag information. A safety sensor equipped with this feature.

6. A safety sensor according to any one of claims 1 to 5, A safety sensor in which the frequency band used for wireless communication between the RFID reader and the RFID tag is the HF band.

Images