JP2006279676A - Detection unit, and sensor system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To evade an error in determining the number of connected apparatuses by detecting a connection failure if occurs between the apparatuses, outputting it, and correctly specifying the apparatus positioned at the terminal end of the connection. <P>SOLUTION: Light curtains 30 including light projecting/receiving apparatuses 40, 60, which are opposing and vertically arranged, are disposed over the three surfaces of a press machine in the perspective view of a safety sensor system. The respective light projecting apparatuses 40A-40C and the respective light receiving apparatuses 60A-60C of the three light curtains 30A-30C are electrically and serially connected with a connection cable 93. A terminal cap 95 is mounted on the light projecting apparatus 40C and the light receiving apparatus 60C positioned at the terminal end of the connection, to specify an end slave, based on the mounting of the terminal end cap 95. Consequently, when the connection failure exists between the light projecting apparatuses 40 or between the light receiving apparatuses 60, the apparatus with the connection failure is not erroneously determined to be the end. Thus, the number of connected apparatuses is not erroneously determined. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a detection unit and a sensor system.

  Conventionally, when a plurality of operation devices that perform a predetermined operation are gathered, a system has been proposed in which the entire operation device group is integrated to perform regular operation control according to a predetermined rule (Patent Document 1). ).

  As shown in FIG. 9A, each of the operation devices 10A to 10C includes connection determination units 11A to 11C, signal reception units 12A to 12C, signal transmission units 13A to 13C, signal transmission units 14A to 14C, and signals. 15A to 15C, electrically connecting the signal transmission unit 13 of one operating device and the signal receiving unit 15 of another operating device, and the signal receiving unit 12 of one operating device and the other The operating devices 10A to 10C are connected in series by electrically connecting the signal transmitting unit 14 of the operating device. Then, when one of the devices 10A to 10C connected in series and located at the end of the connection (here 10A) is connected to a power source, power is supplied to the devices 10B and 10C through the device 10A at the end. The

This type of operation device can automatically determine the number of connected devices, and an example of the determination method is as follows.
(1) H level signals are transmitted from the signal transmission units 13A to 13C and 14A to 14C of the devices 10A to 10C, respectively.
(2) Signals are received by the receiving units 12A to 12C and 15A to 15C, and the connection state is determined (see FIG. 9B).
That is, since the signal of the receiving unit 12A is present in the apparatus 10A but the signal of the receiving unit 15A is not present, it can be determined that the device is a master unit directly connected to the power source. On the other hand, in the case of the device 10B, since both the receiving units 12B and 15B have a signal, it can be determined that the slave is supplied from the power source through the master unit and that a slave lower than the slave is connected.

In the case of the device 10C, since there is no signal from the receiving unit 12C and the signal from the receiving unit 15C is present, it can be determined that the device is the lowest slave.
In this way, the master and the lowest slave are identified based on the combination of the presence / absence of signals input to the receiving units 12A to 12C and 15A to 15C, and thereafter, the master and the lowest slave are connected. It is possible to calculate the number of connections by determining the number of devices.
Japanese Patent No. 3465263

However, if the connection status of the devices (specification of the lowest slave) is determined based only on the presence / absence of signals transmitted / received between the devices connected in series, there is a connection failure between the devices. There is a risk of misjudging the connection status. This is because, for example, when there is a poor connection between the device 10B as the lower slave 1 and the device 10C as the lower slave 2 as shown in FIG. 10A, the signal of the receiving unit 15B of the device 10B. Becomes yes, and the signal of the receiving unit 12B becomes no. This combination of signals is the same as the combination of signals received by the receivers 12 and 15 of the lowest slave.
Therefore, the device 10B erroneously determines itself as the lowest slave, despite the connection failure with the device 10C.
As described above, there is a concern that if the connection status of the device (specification of the lowest slave) is mistaken, the number of devices connected cannot be correctly determined.
The present invention has been completed based on the above circumstances, and when there is a connection failure between devices, this is detected and output, and the one located at the end of the connection is correctly identified. The purpose of this is to avoid errors in determining the number of connected units.

  As means for achieving the above object, the invention of claim 1 is a connection means for performing electrical connection with the other ends of the main body for detecting the physical quantity from the object and determining the presence or absence of the object. A plurality of detection units, each of which is connected to each other in series by electrically connecting the connection means to each other, and the other ends of the detection unit located at the end of the connection, A sensor system in which a connection means covering member is attached to an end portion that is not used for connection with a unit, wherein signals are transmitted and received between the detection units through the connection means. In what determines the number of connections, whether each detection unit is located at the end of the connection based on whether or not the connection means covering member is attached to the detection unit, End determination means for determining whether or not the termination signal output means transmits the termination signal to a higher-order detection unit closer to the start end in the connection direction through the connection means when it is determined that the terminal is in the connection direction. When the termination signal transmitted from the lower detection unit is received, signal transfer means for sequentially transferring the termination signal to the upper detection unit is provided, and the start detection unit, or each detection unit, A connection state determination unit that determines a connection state between detection units based on whether a termination signal is received, and an output circuit that outputs when the connection state determination unit determines that the connection is abnormal are provided. It has the characteristics in the place.

  According to a second aspect of the present invention, in the first aspect, the detection unit at the starting end is a master, and the other detection units operate according to a control signal output from the master or a slave higher than the self. Both the master and the slave detection units are both a light projecting unit composed of a plurality of light projecting elements arranged in a line, or a plurality of optical axes corresponding to each light projecting element. It is characterized in that it is a light receiving unit composed of a plurality of light receiving elements to be formed.

According to a third aspect of the present invention, in the first aspect of the present invention, the connection means provided at both ends of the main body is configured such that one side is for upper connection and the other side is for lower connection, and each connection means Consists of a transmitting means capable of transmitting an electrical signal and a receiving means which is paired with this and capable of receiving an electrical signal,
The detection unit is configured to output a confirmation signal through the transmission means for the lower side connection among the transmission means, and the connection means covering member is attached to the detection unit. Sometimes, the transmission means for the lower side connection and the reception means for the lower side connection paired therewith are short-circuited, and the confirmation signal output from the transmission means for the lower side connection is used for the lower side connection. A short-circuit means for feeding back to the receiving means is provided, and the terminal judging means is configured to judge the presence or absence of the connecting means covering member based on the feedback of the confirmation signal.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the short-circuit unit is connected to the transmission unit and the reception unit for the lower-order connection as the connection unit covering member is attached to the detection unit. It is characterized in that both are short-circuited.

  According to a fifth aspect of the present invention, in the apparatus according to the third or fourth aspect, when the connection means covering member is mounted on the detection unit between the connection means covering member and the detection unit, It has a feature in that a seal member for sealing is inserted.

  According to a sixth aspect of the present invention, in the apparatus according to any one of the second to fifth aspects, a dedicated connection auxiliary member is used for connection between the detection units or for connection between the detection unit and a power source. The detection unit is provided with a unit determination circuit for determining whether the detection unit is a master or a slave, the connection auxiliary member is connectable to the unit determination circuit, and the unit determination circuit includes In contrast, an identification signal transmitting means capable of transmitting a master identification signal or a slave identification signal is provided.

  The invention of claim 7 is a detection unit comprising at least a pair of connection means for making an electrical connection with another body part for detecting a physical quantity from an object and determining the presence or absence of the object, wherein the connection The detection units are connected in series by electrically connecting the means to each other, and the end of the detection unit located at the end of the connection that is not used for connection to other units The connection unit covering member is attached to the detection unit, and the detection unit is provided with a termination signal output unit capable of outputting a termination signal based on the presence or absence of the connection unit coating member.

<Invention of Claim 1 and Invention of Claim 7>
If the end is determined based on the presence or absence of the connecting means covering member, the detection unit in the middle of the connection is not erroneously determined as the end. Thus, if the position of the end can be correctly specified, the number of connected units can be correctly determined by transmitting and receiving signals between the detection units including the start and end.
Further, a termination signal is transmitted from the detection unit at the end to the upper detection unit through the connection means. Therefore, the upper detection unit can determine the connection state based on whether the termination signal is received or not. In other words, receiving a termination signal means that communication is normally performed at least on the lower side than itself, and conversely, not receiving a termination signal means that communication is abnormal. It can be determined that there is a connection failure. If the connection state determination function is provided in this way, when there is a connection failure, an abnormal output can be made to notify the operator of the connection abnormality.

<Invention of Claim 2>
A sensor including a light projecting unit and a light receiving unit having a plurality of optical axes is installed, for example, at a boundary between a safe area and a dangerous area such as a factory. In this case, if the units can be connected to each other, the detection range can be variously changed according to the use situation, and convenience is enhanced.
In addition, with respect to such a sensor system for ensuring safety, if the number of connected units can be correctly determined, the safety is increased accordingly, and as a result, the merchantability of the sensor system is increased.

<Invention of Claim 3>
With such a configuration, a series of configurations for detecting the presence or absence of the connecting means covering member is a very simple configuration.

<Invention of Claim 4>
In such a configuration, by performing the originally necessary work of attaching the connecting means covering member to the detection unit, the short-circuit terminals are automatically connected to the transmitting means and the receiving means, respectively, and the two are short-circuited. . Therefore, it is not necessary to perform a dedicated work (connection work for short circuit), and the system construction work can be simplified.

<Invention of Claim 5>
With such a configuration, the protection effect of the transmission means and the reception means that are not used for connection is enhanced.
<Invention of Claim 6>
Subsequent to the completion of the connection, identification signals are output from the connection auxiliary member, so that each detection unit that has received these identification signals can determine whether it is a master or a slave.

<Embodiment 1>
A first embodiment of the present invention will be described with reference to FIGS.
In the present embodiment, the safety sensor system is disposed in the vicinity of the press machine P at the boundary between the danger area where entry of the worker is prohibited and the safety area where entry of the worker is allowed, When the body enters the danger area, it is detected. FIG. 1 is a perspective view of a safety sensor system, in which a light curtain 30 composed of light projecting and receiving devices 40 and 60 arranged to face each other is arranged over three surfaces of a press.

  Although mentioned later in detail, each light projector (equivalent to the light projection unit of this invention) 40A-40C of these three light curtains 30A-30C, and each light receiver (equivalent to the light reception unit of this invention) 60A. -60C are electrically connected in series by a connection cable 93 (corresponding to the connection auxiliary member of the present invention) 93, respectively. Then, by transmitting and receiving control signals between the light projectors 40A to 40C and between the light receivers 60A to 60C, the start timings of the light projecting and light receiving operations are made different, so that each light projector 40 and each light receiving device are received. The entire system is managed so that detection operations by the device 60 do not interfere with each other.

  Hereinafter, the single components of the projectors 40A to 40C and the light receivers 60A to 60C will be described first, and then the configuration for connection will be described. Note that the projectors 40A to 40C and the light receivers 60A to 60C all have the same structure, and therefore, the structure of a single unit will be described using the projector 40A and the light receiver 60A as representatives.

  The light projector 40A includes a light projecting unit 51A for performing a light projecting operation in a casing (corresponding to the main body of the present invention) K and a light projecting control unit 41A for controlling this (see FIG. 2). ). The light projecting unit 51A includes a plurality of light projecting elements 53A arranged in a line and a light projecting circuit 52A in which the light projecting elements 53A are connected. The light projecting circuit 52A operates based on a predetermined clock pulse signal sent from a light projecting side control circuit 42A included in the light projecting control unit 41A described below, and sequentially supplies drive signals to the light projecting elements 53A. Thereby, an optical signal is sequentially emitted from each light projecting element 53A.

  The projection control unit 41A includes a projection-side control circuit 42A for controlling the projection circuit 52A described above, and a reception circuit 43A, a transmission circuit 44A, and a transmission connected to the projection-side control circuit 42A, respectively. It comprises a circuit 45A, a receiving circuit 46A, and a master / slave determination circuit 47A.

Next, the configuration of the light receiver 60A will be described. The light receiver 60A includes a light receiving portion 71A for performing a light receiving operation in a casing (corresponding to a main body portion of the present invention) K, and a light receiving control portion 61A for controlling the light receiving portion.
The light receiving unit 71A includes a plurality of light receiving elements 72A arranged in a line so as to form an optical axis in a pair with the plurality of light projecting elements 53A, and the light reception signals output from these light receiving elements 72A are Via the analog switch 73A, the signal lines are combined into a common signal line and taken into the comparator 74A.

  Each analog switch 73A is connected to the light receiving side control circuit 62A via the shift register 75A. Then, the light receiving side control circuit 62A takes in the previous clock pulse signal (hereinafter referred to as a synchronizing signal) from the light emitting side through a synchronizing line (not shown), and this is sent to the shift register 75A. Yes. Accordingly, a gate control signal for turning on each analog switch 73A is sequentially sent to each analog switch 73A, and only the light reception signal of the light receiving element connected to the analog switch 73A that has been turned on is input to the comparator 74A.

  The comparator 74A outputs a light-shielding detection signal when the light-receiving signal falls below the set reference value X1, that is, in a light-shielding state, and is taken into the light-receiving side control circuit 62A.

The light reception control unit 61A includes a light reception side control circuit 62A for controlling the light reception unit 71A described above, and a reception circuit 63A, a transmission circuit 64A, a transmission circuit 65A, a reception circuit connected to the light reception side control circuit 62A, respectively. The circuit consists of a circuit 66A and a master / slave determination circuit 67A. The reception circuit 63A and the transmission circuit 64A form one set, and the reception terminal 83A and the transmission terminal 84A are connected to these circuits, respectively.
On the other hand, the transmission circuit 65A, the reception circuit 66A, and the master / slave determination circuit 67A are also in one set, and a transmission terminal 85A, a reception terminal 86A, and a determination terminal 87A are connected to the circuit.

  The light reception control unit 61A is provided with an output circuit (not shown). This output circuit operates based on a display control signal from the light receiving side control circuit 62A, and supplies a drive current to a display unit (not shown). The display unit includes an abnormal indicator lamp made of, for example, an LED and an LCD display panel.

  Although not described above, in the present embodiment, the casing K has a cylindrical shape that is long in one direction, and both end portions serve as connection surfaces for other light receivers. The reception terminal 83A and the transmission terminal 84A described above are arranged on one connection surface of the casing K, whereas the transmission terminal 85A, the reception terminal 86A, and the determination terminal 87A are arranged on the other connection surface. It is like that. In FIG. 2, for convenience, it is assumed that the upper surfaces 82A, 82B, and 82C and the lower surfaces 81A, 81B, and 81C of each light reception control unit 61 are connection surfaces (connection surfaces with other light receivers). , 84A, 85A, 86A, 87A are drawn to the upper surface side or the lower surface side.

  The receiving circuit 63A (63B, 63C) and the receiving terminal 83A (83B, 83C) connected thereto correspond to the receiving means for the lower side connection of the present invention, and the transmitting circuit 64A (64B, 64C), The continuous transmission terminals 84A (84B, 84C) correspond to the transmission means for the lower side connection of the present invention. The master / slave determination circuit 67A (67B, 67C) corresponds to the unit determination circuit of the present invention.

  Next, a connection structure between the light receivers 60A, 60B, and 60C, and a connection structure to a power source (the connection structure on the light projector side is the same as the connection structure on the light receiver side, and the description thereof will be omitted).

  As shown in FIG. 2, connection cables 93 are arranged between the light receiving unit 60A and the light receiving unit 60B, and between the light receiving unit 60B and the light receiving unit 60C, respectively. The connection cable 93 has an attachment portion 93A for the connection surface 82 of each light receiver 60 at one end, and a 93B for the connection surface 81 at the other end, and the reception circuit 63 of one light receiver 60 and the transmission circuit of another light receiver 60. 65 is electrically connected, and the transmission circuit 64 of one light receiver 60 and the reception circuit 66 of another light receiver are electrically connected.

A terminal cap (corresponding to the connecting means covering member of the present invention) 95 is attached to the upper surface 82C of the light receiver 60C. The end cap 95 is formed to have a size that covers the entire upper surface 82C, and is fixed to the upper surface 82C by pushing the end cap 95 downward from the state while facing the upper surface 82C. It has become.
The termination cap 95 covers the connection surface of the termination portion that is not used for connection with other parts and protects the portion (mainly protection of the reception terminal 83C and the transmission terminal 84C exposed from the connection surface). A short-circuit terminal (corresponding to the short-circuit means of the present invention) 96 is provided.

As shown in FIG. 2, both end portions 97 and 98 of the short-circuit terminal 96 are bent downward in the drawing. When the end cap 95 is opposed to the upper surface 82C, the short-circuit terminal 96 has one end 97 opposed to the reception terminal 83C of the reception circuit 63C and the other end 98 opposed to the transmission terminal 84C of the transmission circuit 64C. As the end cap 95 is attached to the light receiver 60C, one end 97 of the short-circuit terminal 96 is connected to the reception terminal 83C of the reception circuit 63C, and the other end 98 is connected to the transmission terminal 84C of the transmission circuit 64C.
Thus, when the end cap 95 is attached to the light receiver 60C, at the same time, the short circuit terminal 96 shorts between the reception circuit 63C and the transmission circuit 64C.

  On the other hand, a start end cap (corresponding to the connection auxiliary member of the present invention) 91 is attached to the lower surface 81A of the light receiver 60A. The start end cap 91 is for connection between the power source and the light receiver 60, and a power cable (not shown) is connected to the cap 91.

  Thus, the light receivers 60A, 60B, and 60C are electrically connected in series by the connection cable 93, and power is supplied from the power source side to the light receiver 60A through the power cable. Electric power is supplied to the light receiver 60B, and further, electric power is supplied to the terminal light receiver 60C through the intermediate light receiver 60B.

  By the way, the optical receiver group composed of the optical receivers 60A, 60B, 60C connected in series with each other can determine the number of connected devices independently of the operation from the outside. In this self-determination, when a determination signal R is transmitted from a light receiver (60A in this case) connected to a power source, each of the light receivers 60B and 60C that has received the signal transmits and receives a signal according to a signal processing pattern described later. This is done by sending the signal R back to the light receiver 60A that is the signal transmission source.

The signal processing pattern is determined by the light receiver (here, the light receiver 60A), the intermediate light receiver (here, the light receiver 60B), and the terminal light receiver (here, the light receiver 60C) of the connection. Therefore, prior to determining the number of connected units, it is necessary for each of the light receivers 60A, 60B, and 60C to specify their own connection order, and this is done in the following manner.
The connection order here refers to the order related to the connection direction (series direction) of the respective light receivers 60, the side closer to the power supply is the higher order (start side), and the side far from the power supply is the lower order (end side). It becomes. The highest one is a master that controls all of the light receivers 60 including itself, and the others are slaves that are supplied with power through the master and operate according to control signals transmitted from the master. .

A configuration in which the master (the uppermost light receiver) is specified will be described.
The start end cap 91 described above is provided with a master setting unit (corresponding to the identification signal transmitting means of the present invention) 92. When the cap 91 is assembled, the master setting unit 92 is configured to be electrically connected to the master / slave determination circuit 67A of the light receiver 60A. After the connection, the master / slave determination circuit 67A is connected. Outputs a master identification signal. Thereby, the photoreceiver 60A that has received the identification signal recognizes that it is the master.

  Each of the connection portions 93A of the connection cables 93 described above is provided with a slave setting portion (corresponding to the identification signal transmitting means of the present invention) 94. From the slave setting portion 94, each light receiver 60B, A slave identification signal is output to the 60C master / slave determination circuits 67B and 67C. Thereby, the light receivers 60B and 60C that have received the identification signal recognize that they are slaves.

Next, the identification of the intermediate slave and the end slave (lowest light receiver) is performed in each light receiver (62B and 62C in this case) based on whether or not the end cap 95 is attached. More specifically, if the light receiving side control circuit 62B of the light receiver 60B and the light receiving control circuit 62C of the light receiver 60C have the terminal cap 95 attached thereto, they recognize that they are end slaves and If it is not installed, it identifies itself as an intermediate slave.
Note that the control content for determining whether or not the light receiving side control circuit is located at the end of the connection based on the presence or absence of the end cap corresponds to the control content performed by the end determination means of the present invention.

Hereinafter, a specific procedure for determining the presence or absence of the end cap 95 will be described with reference to FIG.
In step 1, the light receiving side control circuits 62A to 62C of the light receivers 60A to 60C output an L level (low level) signal to the connection destination through the transmission circuits 64A to 64C and the transmission circuits 65A to 65C. This is performed almost simultaneously in all the light receivers 60A, 60B, 60C.

In step 3, the levels of the signals output from the transmission circuits 64A, 64B, and 64C of the light receivers 60A, 60B, and 60C are simultaneously switched from the L level to the H level (high level). Whether or not the voltage levels of the receiving circuits 63A, 63B, and 63C (the voltage levels of the receiving terminals 83A, 83B, and 83C) are at the H level is determined based on whether the light receiving side control circuit 62A of each of the light receivers 60A, 60B, and 60C 62B and 62C perform each.
Note that the reason for determining the photoreceiver 60A is that the case where the number of connected units is one (no slaves) is taken into consideration. In step 3, the switched signals (H level signals) output from the transmission circuits 64A, 64B, and 64C correspond to the confirmation signals in the present invention.

Here, in the case where the terminal cap 95 is attached, the transmission terminal 84 (here, 84C) of the transmission circuit 64 and the reception terminal 83 (here, 83C) of the reception circuit 63 are short-circuited by the short-circuit terminal 96. Therefore, the H level signal output from the transmission circuit 64C is fed back to the reception circuit 63C through the short-circuit terminal 96. Therefore, when the signal level of the transmission circuit 64C is switched from the L level to the H level, it follows this. The voltage level of the receiving circuit 63 is switched from the L level to the H level.
From the above, in the photoreceiver 60C, the voltage level of the receiving circuit 63C becomes H level in Step 3, and it is recognized by the light receiving side control circuit 62C that there is a termination cap in Step 5.

On the other hand, if the terminal cap 95 is not attached, no signal is transmitted / received between the receiving circuit 63 and the transmitting circuit 64, so that the signal level of the transmitting circuit 64 is not changed. The voltage level of the reception circuit 63 is controlled by the output signal on the transmission circuit 65 side (the output signal of the transmission circuit of the light receiving device on the lower side when viewed from the self) and becomes the L level.
From the above, in the photoreceiver 60B, the voltage level of the receiving circuit 63B becomes L level in step 3, and in step 7, it is recognized by the light receiving side control circuit 62B that there is no termination cap.

Thus, when the types of intermediate and end slaves are specified, each light receiving side control circuit 62A, 62B, 62C of each light receiver 60 has a signal processing pattern corresponding to its own type, that is, an end slave if it is an end slave. If the signal processing pattern is an intermediate slave, the intermediate signal processing pattern is read from the storage means (not shown), and the connected number determination process described below is performed. The signal processing pattern for the end means that when the determination signal R is received from the higher-level slave during the connected number determination process, the information included in the signal is updated, and then the updated determination signal R is This is a process of sending back to the slave on the upper side together with the termination signal F indicating that it is the end.
On the other hand, the signal processing pattern for the intermediate slave includes the downstream signal processing and the upstream signal processing. When the reception circuit 66 (66B in this case) receives the signal, the downstream signal processing is performed and the reception processing is performed. When the circuit 63 (63B in this case) receives a signal, signal processing for uplink is performed.

  As shown in FIG. 4, the number-of-connections determination process is started when the optical receiver 60A serving as a master outputs a determination signal R from the transmission circuit 64A. The determination signal R has, for example, specific information 1 as its content.

  The determination signal R output from the light receiver 60A is received by the receiving circuit 66B of the light receiver 60B. Thereby, the light receiver 60B performs signal processing according to the downstream signal processing. The downlink signal processing is processing for transmitting the determination signal R from the upper slave to the lower slave after performing the update processing.

  Therefore, when receiving the determination signal R, the light receiving side control circuit 62B increments the specific information and updates it from 1 to 2, and then transmits the updated determination signal R to the light receiver 60C through the transmission circuit 64B.

The photoreceiver 60C that has received the determination signal R performs signal processing in accordance with the signal processing pattern for the previous end slave. That is, when receiving the determination signal R, the light receiving side control circuit 62C increments the specific information and updates it from 2 to 3. The light receiving side control circuit 62C sends the updated determination signal R back to the light receiver 60B through the transmission circuit 65C, and transmits a termination signal F to the light receiver 60B through the transmission circuit 65C before and after this.
Note that the control content that the light receiving side control circuit 62C transmits the termination signal F to the light receiver 60B through the transmission circuit 65C corresponds to the control content performed by the termination signal output means of the present invention.

  Both the determination signal R and the termination signal F transmitted from the light receiver 60C are received by the receiving circuit 63B of the light receiver 60B. Thereby, the light receiver 60B performs signal processing according to the upstream signal processing. In the upstream signal processing, when a signal from a lower slave is received, the presence / absence of the termination signal F is confirmed, and then the determination signal R and the termination signal F are transferred to the upper slave.

  Therefore, when the light receiving side control circuit 62B of the light receiver 60B receives a signal through the receiving circuit 63B, it determines whether or not the terminal signal F is included in the received signal. Then, if the termination signal F is received, the light receiving side control circuit 62B does not update the specific information included in the determination signal R, and the received determination signal R and the termination signal F are directly used as a master through the transmission circuit 65B. To the photoreceiver 60A.

In this upstream signal processing, a signal confirmation time is set. After the downstream signal processing described above is performed, the termination signal F is not input within a predetermined time (signal confirmation time). Otherwise, an abnormality is determined (details will be described later).
Further, when the light receiving side control circuit 62B receives a signal through the receiving circuit 63B, the control content for determining whether or not the termination signal F is included in the received signal is the connection state determining means of the present invention. This corresponds to the control content fulfilled by.
Further, the control content of transferring the termination signal F received by the light receiving side control circuit 62B to the light receiver 60A through the transmission circuit 65B corresponds to the control content performed by the signal transfer means in the present invention.

  Through the above signal processing process, the determination signal R and the termination signal F are taken into the optical receiver 60A as the master through the receiving circuit 63A. Then, the light receiving side control circuit 62A determines whether or not the received signal includes the termination signal F. If the termination signal F is included, the electrical signal between the light receivers 60A, 60B, and 60C is determined. That there is no abnormality in the connection.

  And based on the update frequency of specific information, the connection number of the light receiver 60 including self is determined. Here, since the number of updates is two, it is determined that the number of connections of the light receiver 60 including itself is three. At this time, a display control signal is output from the light receiving side control circuit 62A of the master to an output circuit (not shown), and an output operation corresponding to this is performed, so that the number of units connected to the LCD display panel is three. Display is made. Note that, on the light emitting side, the connected number determination process is performed in the same manner as the light receiving side.

  Next, a case where there is a connection abnormality between the light receivers 60 will be described.

Here, a case where there is a connection failure between the light receiver 60B and the light receiver 60C will be described as an example (see FIG. 5). First, regarding the order of connection of each light receiver 60, the light receiver 60A is recognized as a master in the above manner, while the light receiver 60B having a connection abnormality is recognized as an intermediate slave. This is because the authorization of the intermediate slave and the end slave is determined based on the presence / absence of the end cap 95.
The process of determining that there is no cap will be described in detail. The reception circuit 63B of the light receiver 60B and the transmission circuit 65C of the light receiver 60C are in an electrically disconnected state, and The receiving terminal 83B of the receiving circuit 63B is grounded via a resistor R. Therefore, when the processing in step 3 is performed, the voltage level of the receiving circuit 63B is always at the L level regardless of the switching of the level of the output signal of the transmitting circuit 64B, so that the light receiver 60B is an intermediate slave. Determined.

  Therefore, when the connected number determination process is started by the master, the poorly connected light receiver 60B performs signal processing according to the signal processing pattern for the intermediate slave, as in the case of regular connection.

  Therefore, as shown in FIG. 5, when the determination signal R is transmitted from the photoreceiver 60A as the master, the photoreceiver 60B that receives the determination signal updates the specific information and then transmits it to the photoreceiver through the transmission circuit 64B. Transmit to 60C. However, since the connection between the light receiver 60B and the light receiver 60C is in a poor connection state, a signal (termination signal) is not transmitted from the light receiver 60C to the light receiver 60B, and the previous signal confirmation time elapses. Then, the light receiver 60B determines that there is an abnormality, and turns on the abnormality indicator lamp through an output circuit (not shown).

  Next, when the end cap 95 is not attached, and when the end cap 95 is not attached correctly, the end light receiver 60C determines that the connection is abnormal. That is, in such a case, the photoreceiver 60C is recognized as an intermediate slave (determined as intermediate due to the absence of the termination cap 95). Then, as in the case of the previous connection failure, after the downlink signal processing is performed, the input of the termination signal F is waited, but the predetermined signal confirmation time elapses without the termination signal F being input. To do. As a result, the light receiver 60C determines that the connection is abnormal.

  Thus, by lighting the abnormality indicator lamp, it is possible to notify the operator of connection abnormality and forgetting to attach the end cap 95. In this case, the connection and the like are performed again, and then the connected number determination process is performed again. If the connection failure or the like is eliminated and the connection state is normal (the terminal cap 95 is correctly attached to the terminal light receiver 60C and the light receivers 60A to 60C are connected), the LCD display panel is displayed. The number of connected units is displayed.

Next, a detection operation for detecting the presence / absence of a light shielding object by each light curtain 30 will be briefly described.
When the start switch is turned on, the master projector 40A transmits a synchronization signal to the master light receiver 60A through the synchronization line, and transmits to the projector 40B connected in series through the transmission circuit 44A. Then, when the projector 40B and the light receiver 60A receive the synchronization signal, they sequentially transfer the synchronization signal to the lower side connected in series. Thus, the synchronization signal is transmitted to all of the projector / receivers 40 and 60, and the entire system is synchronized.

  When the entire system is synchronized, the master projector 40A transmits a start signal to the master light receiver 60A through the synchronization line. The start signal is a signal for determining the start timing of the detection operation of the light curtain 30, and simultaneously with the transmission of the start signal, the master projector 40A sequentially causes the light projecting elements 53A to emit light at a timing synchronized with the synchronization signal. A series of light projection operations are performed. On the other hand, when receiving the start signal output from the master projector 40A, the master light receiver 60A sequentially selects the light receiving elements 72A at a timing synchronized with the above-described synchronization signal and performs a series of light receiving operations.

  When a series of light projecting operations is completed, the master projector 40A transmits a light projection start signal (corresponding to the control signal of the present invention) to the lower projector 40B through the transmission circuit 44A, and at the same time, the master The light receiver 60A transmits a light reception start signal (corresponding to the control signal of the present invention) to the lower light receiver 60B through the transmission circuit 64A.

Thus, the projector 40B that has received the projection start signal performs a series of projection operations in the same manner as in the case of the master, and when the projection operation is completed, the projector 40B starts projection to the lower projector 40C through the transmission circuit 44B. Send a signal.
On the other hand, the light receiver 60B that has received the light reception start signal performs a series of light reception operations in the same manner as in the case of the master, and when the light reception operation is completed, the light reception start signal is transmitted to the lower light receiver 60C through the transmission circuit 64B. Send.

  Thus, the lowest projector 40C receives the light projection start signal, and at the same time, the lowest light receiver 60C receives the light reception start signal. Then, when a series of light projecting / receiving operations are completed, the lowest light projecting and light receiving devices 40C and 60C now send an end signal back to the upper light projecting device 40 and light receiving device 60 through transmission circuits 45 and 65.

  The light-sending end signal sent back is eventually received by the projector 40A. On the other hand, also on the light receiving side, the returned end signal is received by the light receiver 60A. When the light receiver 60A receives the end signal, it transmits this end signal to the projector 40A through the synchronization line. When the projector 40A as the master receives both the end signals on the light emitting side and the light receiving side, it transmits the previous start signal again at substantially the same timing. Thereby, the light projecting operation and the light receiving operation are sequentially performed again by the light projectors 40A, 40B, and 40C and the light receivers 60A, 60B, and 60C.

  As described above, the detection operations (light projection and light reception operations) of the light curtains 30A, 30B, and 30C are performed in a time-sharing manner, thereby preventing mutual interference between the light curtains 30A, 30B, and 30C. Yes.

  The configuration and control contents of the safety sensor system in the present embodiment have been described above, and the operation will be described next. According to this embodiment, prior to determining the number of connected units, first, the types of master, intermediate slave, and end slave are specified for each of the light receivers 60A, 60B, and 60C. When the type is specified, this time, the number of connected units is determined, that is, the determination signal R is transmitted from the optical receiver 60A as the master, and the optical receiver 60B that receives the determination signal R updates the content of the determination signal R. Then, the determination signal R is transferred to the lower light receiver 60C. Then, the determination signal R is sent back to the optical receiver 60A, which is the master that is the signal transmission source, via the optical receiver 60C, which is the end slave. Then, the photoreceiver 60A as the master determines the number of connected units based on the number of updates of the received determination signal R.

  In such a case, in order to determine the number of connected units without error, it is most important that there is no error in specifying the types of intermediate and end slaves performed prior to the connection determining process. For example, when the number of connected units is 5, for example, the third or fourth intermediate slave when viewed from the master side mistakenly identifies itself as an end slave. Since the signal is sent back to the master via the third or fourth light receiver, the number of connections should be determined to be three in the connection number determination process. It will be determined as four. In the present embodiment, the type of slave is determined based on the presence or absence of the end cap 95, and the end cap 95 can be confirmed to be diagnosed as an end slave, and all others are diagnosed as intermediate slaves. ing.

  Thus, by specifying the type of slave based on the presence or absence of the termination cap 95, when there is a connection failure between the light receivers 60, the light receiver 60 having the connection failure is erroneously determined as an end. Therefore, the number of connected units is not erroneously determined.

  In addition, the light receiver 60C as an end slave outputs a termination signal F to the light receiver 60B on the upper side as viewed from itself before and after sending back the determination signal R. As a result, the upper light receiver 60B can determine whether the connection state on the lower side is higher or lower based on whether or not the termination signal F is received. That is, when the termination signal F is received, it can be determined that communication, that is, the connection between the light receiving units is normally performed at least in the lower part than the self. Then, when the termination signal F is not received within the signal confirmation time, the upper light receiver 60B turns on the abnormality indicator lamp through the output circuit. As a result, the operator can be informed that there is a connection abnormality.

  In addition, in this embodiment, the transmission terminal 84C of the transmission circuit 64C and the reception terminal 83C of the reception circuit 63C are short-circuited by the short-circuit terminal 96, and the signal transmitted from the transmission circuit 64 is fed back to the reception circuit 63. Whether or not the end cap 95 is present is determined based on whether or not it is present. In this manner, since the presence / absence of the end cap 95 is determined using the components (transmission circuit 64 and reception circuit 63) that are inherently necessary, the structure for the determination is extremely simple.

<Embodiment 2>
Next, Embodiment 2 of the present invention will be described with reference to FIG.
The configuration of the second embodiment is different from that of the first embodiment in the configuration for determining the presence or absence of the end cap. As shown in FIG. 6, a magnetoresistive element 113 is provided at a position near the upper surface of the light receiver 110. On the other hand, a magnetic body 116 is provided on the lower surface side of the end cap 115 and at a position facing the magnetoresistive element 113. Thus, when the end cap 115 is attached to the light receiver 110, the magnetic field near the magnetoresistive element 113 changes accordingly. Therefore, since the resistance value of the magnetoresistive element 113 changes due to the change in the magnetic field, the presence or absence of the end cap 115 can be determined by detecting this with the cap detection circuit 112.

<Embodiment 3>
Next, Embodiment 3 of the present invention will be described with reference to FIG.
The configuration of the third embodiment is different from that of the first and second embodiments in the configuration for determining the presence or absence of the end cap.
As shown in FIG. 7, a contact-type mechanical switch 123 is provided at a position near the upper surface of the light receiver 120. The mechanical switch 123 is composed of a pair of L-shaped metal pieces 123A and 123B having different upper surface heights. The mechanical switch 123 is a normally open type, and is closed by pressing one metal piece 123B from above in the figure.

  On the other hand, a pressing piece 126 is provided at a portion of the end cap 125 facing the mechanical switch 123 so as to protrude downward in the figure. When the end cap 125 is attached to the light receiver 120, the metal piece 123B is pushed downward by the pressing piece 126, and the switch 123 is closed. The cap detection circuit 122 detects the opening / closing of the mechanical switch 123 to determine the presence / absence of the end cap 125.

  Further, in the figure, reference numeral 127 denotes a seal ring (corresponding to a seal member of the present invention), which is provided on the entire surface of the end cap 125 facing the light receiving portion 120. When the end cap 125 is attached to the light receiver 120, the seal ring 127 is in close contact with the entire circumference of the upper surface of the light receiver 120, and the end cap 125 and the light receiver 120 are sealed without a gap. Thereby, the receiving terminal 83 of the receiving circuit 63 and the transmitting terminal 84 of the transmitting circuit 64 are not exposed to moisture, and are effectively protected.

  Further, in the case of a normal one, even if the seal ring 127 is provided on the end cap 125, if the end cap 125 is forgotten to be mounted, it is natural that the sealing performance cannot be ensured. However, as described in the first embodiment, when the connected number determination process is performed, if the end cap 125 is not attached, it is determined that there is an abnormality. The end cap 125 is attached. Therefore, it is effective under use conditions where the necessity of sealing is particularly high.

<Embodiment 4>
Next, a fourth embodiment of the present invention will be described with reference to FIG.
In the first embodiment, the process for specifying the type of the light receiver 60 and the connection determination process are performed separately. In the fourth embodiment, the presence or absence of connection of the terminal cap 95 or the lower light receiver is determined. While determining sequentially from the master, the connection determination process proceeds at the same time. Hereinafter, a series of processing when connection is correctly performed (when the number of connections is 3) will be roughly described, and then a case where there is a connection failure will be described. It is assumed that the light receiver 60A recognizes itself as a master in the same manner as in the first embodiment.

  When the processing is started, first, in step 10, the light receiving side control circuit 62 of each light receiver 60 outputs an H level signal to the connection destination through the transmission circuit 64 and the transmission circuit 65. This is performed almost simultaneously in all the light receivers 60A, 60B, 60C.

  In step 20, it is determined whether or not the voltage level of the receiving circuit 63A of the photoreceiver 60A as the master is the H level.

  Since the light receiver 60B is connected to the lower side, the voltage level of the reception circuit 63A follows the signal level transmitted from the transmission circuit 65B of the lower light receiver 60B. Therefore, it is determined Yes in step 20 and the process proceeds to step 30. In step 30, the levels of the signals transmitted from the transmission circuits 64A, 64B, 64C of the respective light receivers 60 are simultaneously changed from the H level to the L level, and then the process proceeds to step 40. At this time, H level signals continue to be output from the transmission circuits 65A, 65B, and 65C of the respective light receivers.

  In step 40, it is determined whether or not the voltage level of each receiving circuit 63A of the light receiver 60A is L level.

  Since the light receiver 60B is connected to the lower level, the voltage level of the reception circuit 63A follows the signal level transmitted from the transmission circuit 65B of the lower level light receiver 60B. Therefore, it is determined No in step 40, and in step 55, communication with the lower light receiver 60B is performed. That is, the light receiver 60A transmits the determination signal R described above to the light receiver 60B through the transmission circuit 64A.

  Then, the determination signal R is received by the light receiver 60B. When the light receiver 60B receives the determination signal R, it performs a series of steps 10 to 55. In the case of the photoreceiver 60B as well, since the photoreceiver 60C is connected to the lower level, the result is Yes in Step 20, No in Step 40, and the process proceeds to Step 55. In step 55, communication is performed with the lower light receiver 60C. At this time, the light receiver 60B updates the content of the determination signal R received from the light receiver 60A and transmits it to the receiver 60C (intermediate slave signal processing in the first embodiment).

  When receiving the updated determination signal R, the light receiver 60C performs a series of processes of Steps 10 to 55. In this case, although it is determined Yes in Step 20, since it is the end cap 95 that is connected to the lower side of the light receiver 60C, YES is determined in the determination process in Step 40, and then the process proceeds to Step 51 To do. In step 51, it is determined that the self is an end slave, and thereafter, communication is performed with respect to the upper light receiver 60B having a higher connection order as seen from the self. That is, the determination signal R is updated and sent back, and the termination signal F is transmitted from the transmission circuit 65C before and after this (signal processing for the end slave in the first embodiment).

  Thereafter, the determination signal R and the termination signal F that are sent back are received by the optical receiver 60A, whereby the number of connected units is determined based on the number of updates of the determination signal R in the same manner as in the first embodiment.

  On the other hand, if the end cap 95 is forgotten to be attached and if there is a connection failure between the light receivers 60, it is determined No in step 20. This is because the receiving terminal 83 of the receiving circuit 63 is connected to the ground via the resistor R, so that when there is no lower connection, the voltage level of the receiving circuit 63 is always L level.

  By performing such a determination process (mainly the process in step 20), whether or not the end cap 95 is attached and whether or not the connection state between the light receivers 60 is good is determined based on the presence or absence of the end signal F in the first embodiment. Since it is possible to check twice, it is possible to construct a more reliable system.

<Other embodiments>
The present invention is not limited to the embodiments described with reference to the above description and drawings. For example, the following embodiments are also included in the technical scope of the present invention, and further, within the scope not departing from the gist of the invention other than the following. Various modifications can be made.

  (1) In the above-described embodiment, a light curtain including a projector and a light receiver has been described as an example. However, the present invention is applicable as long as devices that perform the same operation are connected in series to detect an object.

  (2) In the above embodiment, the master and the slave are identified using the connection auxiliary member used for the connection between the light receivers, but may be performed by transmitting and receiving signals between the light receiving units.

1 is a perspective view of a safety sensor system according to Embodiment 1. FIG. The figure which shows the state where light projectors and light receivers were connected in series, respectively. The flowchart figure which shows the process sequence for determination of the presence or absence of an end cap The figure which shows a mode that the judgment signal transmitted from the master is sent back to the master via the end slave Diagram showing how the judgment signal is interrupted at the poor connection The figure which shows the structure for determining the presence or absence of the termination | terminus cap which concerns on Embodiment 2. FIG. The figure which shows the structure for determining the presence or absence of the termination | terminus cap which concerns on Embodiment 3. FIG. The flowchart figure which shows the process sequence for determining the connection state of the light receiver which concerns on Embodiment 4, or a projector. Figure showing a conventional example The figure which similarly shows the conventional example

Explanation of symbols

60. Light receiver (detection unit)
62. Light receiving side control circuit (terminal determination means, termination signal output means, signal transfer means, connection state determination means)
63, 66 ... receiving circuit (receiving means)
64, 65 ... transmission circuit (transmission means)
95 ... Terminal cap (connecting member covering member)

Claims (7)

A plurality of detection units having connection means for electrical connection with the other are provided at both ends of the main body for detecting a physical quantity from the object and determining the presence or absence of the object, and each of the connection means is electrically connected Connect each detection unit in series by connecting to the connection unit covering member at the end of the detection unit located at the end of the connection, the end of the detection unit not used for connection with other units Is a sensor system in which
In determining the number of connected units by transmitting and receiving signals through the connecting means between the detection units,
For each detection unit,
Terminal determination means for determining whether or not self is located at the terminal of connection based on whether or not the connection means covering member is attached to the detection unit;
Termination signal output means for transmitting the termination signal to a higher-order detection unit closer to the start end in the connection direction through the connection means when it is determined that the terminal is the end in the connection direction;
When the termination signal transmitted from the lower detection unit is received, signal transfer means for sequentially transferring the termination signal to the upper detection unit is provided,
To the detection unit at the start or each detection unit,
Connection state determination means for determining a connection state between detection units based on whether or not the termination signal is received;
A sensor system, comprising: an output circuit that performs output when the connection state determination means determines that there is an abnormality in connection. The start detection unit is a master, and the other detection units are slaves that operate according to a control signal output from the master or a slave higher than the self,
Both of the master and slave detection units are a light projecting unit composed of a plurality of light projecting elements arranged in a line, or a plurality of light receiving units that form a plurality of optical axes corresponding to each light projecting element. The sensor system according to claim 1, wherein the sensor system is a light receiving unit including an element. The connection means provided at both ends of the main body is one side for upper connection and the other side for lower connection, and each connection means is paired with a transmission means capable of transmitting an electrical signal. And a receiving means capable of receiving an electrical signal,
The detection unit is configured to output a confirmation signal through the transmission means for the lower side connection among the transmission means,
When the connection means covering member is attached to the detection unit, the transmitting means for the lower side connection and the receiving means for the lower side connection paired with the connecting means covering member are short-circuited, Short circuit means is provided for feeding back the confirmation signal output from the transmission means for the lower side connection to the reception means for the lower side connection,
The sensor system according to claim 2, wherein the end determination unit is configured to determine the presence or absence of a connection unit covering member based on feedback of the confirmation signal. The said short-circuit means is connected to the transmitting means and the receiving means for the lower-order side connection with the attachment of the connecting means covering member to the detection unit, and short-circuits both. Sensor system. The seal member which seals between both when the said connection means coating | coated member is mounted | worn with the said detection unit is inserted between the said connection means coating | coated member and the said detection unit. The sensor system according to claim 4. In the connection between the detection units, or a connection auxiliary member dedicated to the connection between the detection unit and the power source, respectively,
The detection unit is provided with a unit determination circuit for determining whether it is a master or a slave unit,
The connection auxiliary member is provided with an identification signal transmitting means which can be connected to the unit determination circuit and can transmit a master identification signal or a slave identification signal to the unit determination circuit. The sensor system according to any one of claims 2 to 5. A detection unit comprising at least a pair of connection means for performing electrical connection with another body part for detecting a physical quantity from an object and determining the presence or absence of the object,
The detection units are connected in series by electrically connecting the connection means to each other, and of both ends of the detection unit located at the end of the connection, on the side not used for connection with other units In what the connection means covering member is attached to the end,
The detection unit is provided with termination signal output means capable of outputting a termination signal based on the presence or absence of the connecting means covering member.

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