JP5154281B2 - Multi-optical axis photoelectric sensor receiver, multi-optical axis photoelectric sensor - Google Patents

Description

  The present invention relates to a photoreceiver for a multi-optical axis photoelectric sensor and a multi-optical axis photoelectric sensor.

2. Description of the Related Art Conventionally, a projector having a plurality of light projecting elements and a light receiver having a plurality of light receiving elements arranged to constitute an optical axis so as to face the plurality of light projecting elements, respectively, cross the optical axis. A multi-optical axis photoelectric sensor that detects the presence or absence of a light shielding object is known. In this type of multi-optical axis photoelectric sensor, light is projected and received between each light axis composed of each light projecting element and a light receiving element that is paired therewith, and a detection signal output from each light receiving element is shared. Input to the comparator through the output line. Then, the signal level of the detection signal is determined by a comparator, and the presence / absence of a light-shielding object crossing each optical axis is detected (the following Patent Documents 1 and 2, etc.).
JP 2002-118452 A Japanese Patent Laid-Open No. 11-355115

In the above, since the detection signal is input to the comparator through the common output line, if the output line is disconnected, a normal detection operation cannot be performed. In this case, connection confirmation is performed, but such confirmation work takes time and effort to identify where the problem is in the connection.
The present invention has been completed based on the above circumstances, and an object thereof is to provide a multi-optical axis photoelectric sensor having an output line disconnection diagnosis function and excellent in maintainability.

  The present invention is a plurality of light receiving elements, and a plurality of signal passing switching elements that are connected to the output sides of the plurality of light receiving elements and pass detection signals output from each light receiving element on condition that they are turned on, Light receiving control means for sequentially turning on and off the plurality of signal passing switching elements, an output line in which the output sides of the plurality of signal passing switching elements are commonly connected, and detection of each of the light receiving elements input through the output line And a discriminating means for discriminating the light shielding state of each light receiving element based on the level of the signal. Each light receiving element performs a light receiving operation for detection for detecting the light shielding state for each light receiving element. A multi-optical axis photoelectric sensor photoreceiver that discriminates the light-shielding state by the discriminating means, the output line and a diagnostic switch on one end side of the output line A diagnostic circuit including a diagnostic power source connected via a switching element and an impedance element provided at the other end of the output line as a component, and at a timing other than the detection light receiving operation of the light receiving element. And diagnosing the presence or absence of disconnection of the output line by monitoring the level of the terminal voltage of the impedance element when the diagnostic switching element is switched from the OFF state to the ON state and the diagnostic circuit is energized. And a disconnection diagnosis means.

As an embodiment of the present invention, the following configuration is preferable.
The plurality of signal passing switching elements and the diagnostic switching element are connected to a shift register, and the control device constituting the light reception control means passes the shift register through the plurality of signal passing switching elements. , And the diagnostic switching elements are sequentially turned on and off. In this way, each switching element can be controlled to be turned on / off by one device (that is, a shift register), and control of the switching element is not complicated.

The on / off control procedure of the switching element by the shift register is set to the order in which the diagnosis switching element for on / off control is performed after the plurality of signal passing switches are on / off controlled. In this way, after a series of light receiving operations, it is possible to subsequently diagnose whether or not the output line is disconnected. If the output line is disconnected, it can be detected at an early stage.

-Among the plurality of signal passing switching elements, a switching element connected at a position closest to the one end side with respect to the output line is included in a part of the diagnostic circuit, whereby the diagnostic circuit The circuit configuration is such that the switching element is shared by the switching element included in the diagnostic circuit. In this way, the number of switching elements can be reduced and the circuit configuration can be simplified.

The light receiving element, the corresponding signal passing switching element, and the output line are unitized as a circuit block for one or a plurality of sets, and ends of the output lines included in the unitized circuit block Is electrically connected with a connector, so that the light receiving elements are connected in multiple stages, and the disconnection diagnosis means is configured to transmit the light receiving elements at a timing other than the light receiving operation for the detection. The connection failure of the connector is detected by monitoring the level of the terminal voltage of the impedance element when the diagnostic switching element is switched from the off state to the on state and the diagnostic circuit is energized. With such a configuration, when the light receiver does not operate normally, if the cause is due to poor connection of the connector, the disconnection diagnosis means can immediately diagnose, so the operator can There is no need to visually check the connection state, and the maintainability is excellent.

  The present invention corresponds to a plurality of light projecting elements, light projecting control means for performing light projecting control for projecting light sequentially from the plurality of light projecting elements at a predetermined timing, and the plurality of light projecting elements. It is provided that the optical axis is provided and a plurality of light receiving elements that receive the light of the corresponding light projecting element and output a detection signal, and are connected to the output side of each of the plurality of light receiving elements and turned on. A plurality of signal passing switching elements that pass detection signals output from the respective light receiving elements, and a light receiving control that sequentially controls the plurality of signal passing switching elements in synchronization with the light projecting timing of the light projecting elements. And an output line in which the output sides of the plurality of signal passing switching elements are commonly connected, and the optical axis is blocked based on the level of the detection signal of each light receiving element input through the output line. A multi-optical axis photoelectric sensor that performs a light projecting / receiving operation for each optical axis and discriminates a light blocking state of each optical axis by the determining unit. A diagnostic power source connected to one end side of the output line via a diagnostic switching element, a diagnostic circuit as an element provided on the other end side of the output line, and other than the light emitting / receiving operation By monitoring the level of the terminal voltage of the impedance element when the diagnostic switching element is switched from the off state to the on state and the diagnostic circuit is energized at the timing of Disconnection diagnosis means for diagnosing the presence or absence.

  The term light projecting / receiving operation of each optical axis used in the invention of the present multi-optical axis photoelectric sensor refers to the light receiving operation for detection used in the invention of the above-described optical receiver for a multi-optical axis photoelectric sensor. This includes the operation on the light emitting side.

As an embodiment of the present invention, the following configuration is preferable.
The plurality of signal passing switching elements and the diagnostic switching element are connected to a shift register, and the light receiving control means controls the plurality of signal passing switching elements via the shift register, and The diagnostic switching elements are sequentially turned on and off. In this way, the switching element can be controlled to be turned on / off by one device (that is, a shift register), and the control of the switching element is not complicated.

The on / off control procedure of the switching element by the shift register is set to the order in which the diagnosis switching element for on / off control is performed after the plurality of signal passing switches are on / off controlled. In this way, after a series of light receiving operations, it is possible to subsequently diagnose whether or not the output line is disconnected. If the output line is disconnected, it can be detected at an early stage.

-Among the plurality of signal passing switching elements, a switching element connected at a position closest to the one end side with respect to the output line is included in a part of the diagnostic circuit, whereby the diagnostic circuit The circuit configuration is such that the switching element is shared by the switching element included in the diagnostic circuit. In this way, the number of switching elements can be reduced and the circuit configuration can be simplified.

The light receiving element, the corresponding signal passing switching element, and the output line are unitized as a circuit block for each of one or a plurality of optical axes, and the end of the output line included in the unitized circuit block It is a circuit configuration in which multiple optical axes are formed by electrically connecting each other with a connector, and the disconnection diagnostic means switches the diagnostic switching element from an off state to an on state at a timing other than the light projecting / receiving operation. The connection failure of the connector is detected by monitoring the level of the terminal voltage of the impedance element when the diagnostic circuit is energized by switching to. With such a configuration, when the multi-optical axis photoelectric sensor does not operate normally, the cause can be immediately diagnosed by the disconnection diagnosis means if the cause is due to poor connection of the connector. However, it is not necessary to visually check the connection state of the connector, and the maintainability is excellent.

  According to the present invention, an output line disconnection diagnosis function is provided. Therefore, when the multi-optical axis photoelectric sensor and the optical receiver for the multi-optical axis photoelectric sensor do not operate normally, it is possible to easily diagnose whether the cause is due to the disconnection of the output line. . Therefore, it becomes possible to provide a multi-optical axis photoelectric sensor excellent in maintainability and a photoreceiver for the multi-optical axis photoelectric sensor.

<Embodiment 1>
In the present embodiment, the multi-optical axis photoelectric sensor U according to the present invention has a boundary between a danger area where entry of an operator is prohibited and a safety area where entry of the worker is allowed in the vicinity of equipment such as a press. When the operator's hand or body enters the danger area, it is detected.

  As shown in FIG. 1, the multi-optical axis photoelectric sensor U is mainly composed of a light projector 10 and a light receiver 20 that are arranged to face each other. Both of the light projecting and receiving devices 10 and 20 have prismatic casings 10A and 20B extending vertically, and a plurality of light projecting elements LED are arranged in the vertical direction on the surface facing the light receiving device 20 on the projector 10 side. Arranged in a row.

  On the other hand, a plurality of light receiving elements PD that form an optical axis F in pairs with the light projecting elements LED are arranged in a line along the vertical direction on the opposing surface of the light receiver 20. The light projecting element LED and the light receiving element PD are arranged in the same order in the vertical direction and are mutually normal counterparts.

  Next, the electrical configuration of the multi-optical axis photoelectric sensor U will be described with reference to FIG. In the following description, for the sake of convenience, the description will be made assuming that the number of optical axes is four. 2, reference numeral 30 denotes a light projection control circuit, reference numerals 41 to 44 denote a light receiving circuit, reference numeral 50 denotes a light receiving control circuit, and reference numeral 60 denotes a control device.

  The light projection control circuit 30 controls the light projector 10 together with the control device 60, and the light projecting elements LED1 to LED4 constituting the light projector 10 are electrically connected. The light projecting control circuit 30 sequentially supplies a drive current to each of the light projecting elements LED1 to LED4 on condition that the light projecting start signal St1 given from the control device 60 is input, and each of the light projecting elements LED1 to LED4 is supplied. Light projection control for sequentially emitting light (light projection) is performed.

  Next, the circuit configuration on the light receiver 20 side will be described. Each of the light receiving elements PD1 to PD4 constituting the light receiver 20 is provided with light receiving circuits 41 to 44, respectively. The light receiving circuits 41 to 44 are connected to signal lines D1 to D4, respectively. Capacitors C1 to C4 and normally open type analog switches (corresponding to “signal passing switching elements” of the present invention) SW1 to SW4 are inserted in these signal lines D1 to D4.

  The light reception control circuit 50 individually controls on / off of the analog switches SW1 to SW4 of the signal lines D1 to D4. Each analog switch SW1 is subjected to input of a light reception start signal St2 provided from the control device 60. The gate signal is sequentially applied to .about.SW4 to turn on each of the signal lines D1 to D4 in order, and energization control is performed so that each signal line is energized. Note that “on” means a closing operation for closing the switch, and “off” means an opening operation for opening the switch.

  In the present embodiment, the light receiving start signal St2 is provided to the light receiving control circuit 50 at a timing synchronized with the light projecting start signal St1 provided by the control device 60 to the light projecting control circuit 30, and each of the light projecting elements LED1 to LED4 is provided. Are sequentially turned on, the corresponding analog switches SW1 to SW4 are sequentially turned on, and only the detection signal of the light receiving element PD paired with each light projecting element LED passes through the analog switch SW. It is configured to be output to the output line Lo described.

  The signal lines D <b> 1 to D <b> 4 are commonly connected to the output line Lo, and one end of the output line Lo is connected to the input terminal 71 of the comparator 70. The comparator 70 compares the input voltage Vin input through the output line Lo and outputs a binary signal of H level or L level. The other input terminal of the comparator 70 is a comparison target. A reference voltage Vref is given. In addition, the voltage value of the reference voltage Vef is set to a value lower than the voltage value of the first DC power supply 81 described later.

  In the present embodiment, when the input voltage Vin input through the output line Lo is lower than the reference voltage Vref, an H level signal is output from the comparator 70 to the control device 60, and the input voltage Vin input through the output line Lo. Is higher than the reference voltage Vref, an L level signal is output.

  The other end of the output line Lo is grounded to the ground GND through a switch SW5 in which a resistor R5 is connected in series. The switch SW5 is configured such that a gate signal is given through the control device 60, and the control device 60 can open and close the switch SW5.

  Further, a signal line is connected between the end point (a) of the resistor R5 on the side where the output line Lo is connected and the input port Pa of the control device 60, and the end point (a) of the control device 60 side is connected to the signal line. The terminal voltage Va can be monitored. The resistor R5 corresponds to the impedance element of the present invention.

  Moreover, the code | symbol 81 shown in FIG. 2 is a 1st DC power supply. The positive electrode of the first DC power supply 81 and one end of the switch SW5 are connected by a resistor R6, and the bias line Lv is drawn from the positive electrode of the first DC power supply 81.

  In this embodiment, an intermediate connection point between the capacitor C1 and the analog switch SW1 provided in the first-stage signal line D1 is connected to the bias line Lv through the resistor R1. Similarly, an intermediate connection point between the capacitor C2 and the analog switch SW2 provided in the second-stage signal line D2 is connected to the bias line Lv through the resistor R2 and provided in the third-stage signal line D3. An intermediate connection point between the capacitor C3 and the analog switch SW3 is connected to the bias line Lv through the resistor R3.

  On the other hand, an intermediate connection point between the capacitor C4 and the analog switch SW4 provided in the fourth-stage signal line D4 is connected to a dedicated second DC power supply (corresponding to “diagnostic power supply” of the present invention) 82 via the resistor R4. Connected. In the present embodiment, the value of the power supply voltage V2 of the second DC power supply 82 is set to a value different from the power supply voltage V1 of the first DC power supply 81. In this embodiment, the second DC power supply 82 is set. The power supply voltage V2 of the first DC power supply 81 is set to “2V”.

  Each set of the capacitor C and the resistor R, that is, the set of the capacitor C1 and the resistor R1, the set of the capacitor C2 and the resistor R2, the set of the capacitor C3 and the resistor R3, and the set of the capacitor C4 and the resistor R4 constitute a differentiation circuit. The detection signals output from the light receiving circuits 41 to 44 are differentiated and then applied to the comparator 70 through the output line Lo.

  The multi-optical axis photoelectric sensor U configured as described above has a failure diagnosis function for the analog switches SW1 to SW4 and a disconnection diagnosis function for the output line Lo in addition to a function for detecting the presence or absence of a light shielding object that blocks the optical axis. Yes.

  Hereinafter, circuit operations of the multi-optical axis photoelectric sensor U will be described in the order of (a) detection, (b) failure diagnosis of the analog switches SW1 to SW4, and (c) output line Lo disconnection diagnosis.

(A) Detection Under the control of the control device 60, the detection operation is performed by sequentially activating the optical axis F serving as the light projecting element LED and the corresponding light receiving element PD. Specifically, first, a light projection start signal St1 is output from the control device 60 to the light projection control circuit 30, and simultaneously with the output of the light projection start signal St1, a light reception start signal is transmitted from the control device 60 to the light reception control circuit 50. St2 is output.

  Thereby, on the light projecting side, each light projecting element LED is driven under the control of the light receiving control circuit 50, and each light projecting element LED1 to LED4 emits light in order. On the other hand, on the light receiving side, under the control of the light receiving control circuit 50, the analog switches SW1 to SW4 connected to the corresponding light receiving elements PD1 to PD4 are sequentially turned on in accordance with the light emission timings of the light projecting elements LED1 to LED4. Operated (see FIG. 4).

  As a result, each optical axis F is sequentially enabled and light projecting / receiving operation is performed between the optical axes F. As a result, a detection signal described below is output from the light receiving element PD, and the light receiving circuits 41 to 44 and the differentiation circuit After passing, it is sequentially taken into the comparator 70.

  Note that the term “detecting light receiving operation” used in the invention of the optical receiver for the multi-optical axis photoelectric sensor means one obtained by excluding the operation on the light projecting side from the light projecting / receiving operation described above.

  The detection signal output by the detection operation is as shown in FIG. 4, and a detection signal (shown in FIG. 4) of a level corresponding to the amount of received light is first output from the light receiving element PD. Then, the detection signal output from the light receiving element PD is inverted and amplified by the light receiving circuits 41 to 44 (shown in FIG. 4), and then the differential circuit (differential circuit constituted by a set of the capacitor C and the resistor R). Differentiated. The differentiated detection signal (shown in FIG. 4) is applied as an input voltage Vin to the comparator 70 through the output line Lo.

  From the above, when the optical axis F is in the incident state, the input voltage Vin is lower than the reference voltage Vref as shown in FIG. As a result, an H level signal is output from the comparator 70 to the control device 60. On the other hand, when the specific optical axis F (third-stage optical axis in the example of FIG. 4) F is in a light-shielding state, the input voltage Vin becomes 2 V, which is the line voltage of the bias line Lv, and exceeds the reference voltage Vref. As a result, an L level signal is output from the comparator 70 to the control device 60.

  Therefore, the control device 60 determines whether the output signal from the comparator 70 is at the H level or the L level, so that each optical axis F is incident or shielded, that is, each optical axis F is in the incident state. Alternatively, it is possible to detect which state is a light shielding state. The processing function performed by the “discriminating means” of the present invention is realized by the discrimination processing performed by the comparator 70 and the control device 60.

  In the present embodiment, when the control device 60 detects that any one of the optical axes F is in the light shielding state, an abnormality detection signal for notifying abnormality is output immediately. During this detection operation, the control device 60 controls the switch SW5 to be turned off.

(B) Failure diagnosis of the analog switches SW1 to SW4 The failure diagnosis of the analog switches SW1 to SW4 is performed by stopping the light projection of all the light emitting elements LED at a timing different from the above detection (timing other than the light projecting / receiving operation). Done. Here, the timing other than the light projecting / receiving operation is not limited to the period A in FIG. 4 in which a series of light projecting / receiving operations are performed. In addition to the section C, the section B in FIG. 4 in which light reception is stopped is included even in the section A in which a series of light projecting and receiving operations are performed.

  Now, a specific procedure of failure diagnosis will be described. First, under the control of the control device 60, all the analog switches SW1 to SW4 are first controlled to be in the OFF state by the light receiving control circuit 50, and then The switch SW5 in the off state is switched to the on state.

  If this is done, if all the analog switches SW1 to SW4 are normally turned off, the terminal voltage Va at the end point (a) of the resistor R5 becomes the ground level, that is, zero volts.

On the other hand, when any one of the analog switches SW1 to SW4 is short-circuited, as shown in FIG. 5 (here, SW1 is short-circuited), a first DC power supply 81, a resistor R1, and a sheet are provided. A closed circuit is configured by the analog switch SW1, the resistor R5, and the switch SW5, and a current flows in the closed circuit. As a result, the power supply voltage V1 of the first DC power supply 81 is divided by the resistors R1 and R5, and the terminal voltage Va at the end point (a) of the resistor R5 becomes the potential of the following equation (1).
Va = V1 × R5 / (R1 + R5) (1) Formula

  From the above, by monitoring the terminal voltage Va at the end point (a) of the resistor R5 accompanying the opening and closing of the switch SW5, the presence or absence of a short circuit can be diagnosed for the analog switches SW1 to SW4.

(C) Disconnection diagnosis of the output line Lo As with the failure diagnosis of the analog switches SW1 to SW4, the failure diagnosis of the output line Lo is performed at a timing different from the above detection (timing other than the light projecting / receiving operation) of all the light emitting elements LED. This is done with the projection stopped. Here, the timing other than the light projecting / receiving operation is not limited to the period A in FIG. 4 in which a series of light projecting / receiving operations are performed. In addition to the section C, the section B in FIG. 4 in which light reception is stopped is included even in the section A in which a series of light projecting and receiving operations are performed.

  Now, when explaining the specific procedure of failure diagnosis, all the analog switches SW1 to SW4 are first controlled to be turned off under the control of the control device 60, and further, the switch SW5 is further controlled to be turned off. The

At this time, the terminal voltage Va at the end point (a) of the resistor R5 is at a level equal to the power supply voltage V1 of the first DC power supply 81.
Va = V1 (2) Formula

  Next, the analog switch (here, the analog switch SW4) on the signal line D4 connected to the connection point (b) on one end side of the output line Lo that is farthest from the resistor R5 is controlled to be in the ON state.

  When the analog switch SW4 is turned on, a closed circuit is formed by the second DC power supply 82, the resistor R4, the analog switch SW4, the output line Lo, the resistor R5, the resistor R6, and the first DC power supply 81, as shown by a thick line in FIG. (Corresponding to the “diagnostic circuit” of the present invention). In addition, in this embodiment, the values of the power supply voltages V1 and V2 of the first and second DC power supplies 81 and 82 are made different, and the current If flows in the closed circuit.

Thereby, when the output line Lo is not disconnected, the terminal voltage Va at the end point (a) of the resistor R5 becomes the potential of the following expression (3).
Va = [R4 × V1 + (R5 + R6) × V2] / (R4 + R5 + R6) (3)

  On the other hand, when the output line Lo is disconnected in the middle, the current If does not flow in the closed circuit, and the terminal voltage at the end point (a) of the resistor R5 regardless of the ON operation of the switch SW4. Va remains the power supply voltage V 1 of the first DC power supply 81.

  From the above, by monitoring the terminal voltage Va at the end point (a) of the resistor R5 accompanying the ON operation of the analog switch SW4, the presence or absence of disconnection of the output line Lo can be diagnosed. That is, if a change occurs in the terminal voltage Va at the end point (a) of the resistor R5 by turning on the analog switch SW4, it can be diagnosed that there is no disconnection. Even if the analog switch SW4 is turned on, the end point (a) of the resistor R5 If there is no change in the terminal voltage Va, it can be diagnosed that there is a disconnection. By the diagnostic processing performed by the control device 60, a processing function that fulfills the disconnection diagnostic means of the present invention is realized.

  Thus, according to the present multi-optical axis photoelectric sensor U, the presence or absence of disconnection of the output line Lo can be easily diagnosed by the on / off operation of the switch SW4. Therefore, it is possible to provide a multi-optical axis photoelectric sensor that is excellent in maintainability.

<Embodiment 2>
Next, a second embodiment of the present invention will be described with reference to FIGS. The second embodiment is obtained by changing a part of the circuit configuration of the multi-optical axis photoelectric sensor U (functional part for performing a disconnection diagnosis of the output line Lo) with respect to the first embodiment.

  The change portion will be described with reference to FIG. 7. In this example, a pair of the first DC power supply 81 and the switch SW6 and a pair of the second DC power supply 82 and the switch SW7 are connected in parallel, The bias line Lv is drawn from the connection point (c). Both the switches SW7 have a circuit configuration to which a gate signal is given from the control device 60, and the control device 60 can control on / off.

  In this embodiment as well, as in the case of the first embodiment, the value of the power supply voltage V2 of the second DC power supply 82 is set to a value different from the power supply voltage V1 of the first DC power supply 81. Specifically, the power supply voltage V2 of the second DC power supply 82 is “3V”, and the power supply voltage V1 of the first DC power supply 81 is “2V”.

  Further, the signal line D4 is connected to the bias line Lv via the resistor R4 in the same manner as the other signal lines D1 to D3 in accordance with the change of the connection destination of the positive electrode of the second DC power supply 82.

  According to this configuration, when both the switch SW5 and the switch SW7 are turned off and the switch SW6 is turned on, the connection similar to the connection shown in FIG. 3 of the first embodiment (the line voltage of the signal line D4 is applied to the bias line). It is different from the first embodiment only in the point taken from Lv), and thereafter, the analog switches SW1 to SW4 provided on the signal lines D1 to D4 are sequentially turned on in synchronization with the operation on the light emitting side. Similarly to the first embodiment, the optical axes F can be sequentially enabled, and the incident light shielding of each optical axis F can be detected.

  Further, failure diagnosis of the analog switches SW1 to SW4 and disconnection diagnosis of the output line Lo can be performed at a timing different from the above-described detection operation (timing other than the light projecting / receiving operation). Here, the timing other than the light projecting / receiving operation may be any light receiving stop state in which all the analog switches SW1 to SW4 are turned off as in the first embodiment, and a series of light projecting / receiving operations are performed. In addition to the section C other than the middle section A, the section B in FIG. 4 in which light reception is stopped is included even in the section A in which a series of light projecting and receiving operations are performed.

  In order to perform failure diagnosis of the analog switches SW1 to SW4, all the analog switches SW1 to SW4 and the switch SW7 are turned off at timings other than the light projecting / receiving operation. What is necessary is just to turn on SW6.

  When this is performed, the terminal voltage Va at the end point (a) of the resistor R5 changes depending on the presence or absence of a short circuit, as in the first embodiment. By monitoring the terminal voltage Va at the end point (a), the analog switch SW1 Can diagnose the presence or absence of SW4 short circuit.

  In order to perform disconnection diagnosis of the output line Lo, all the analog switches SW1 to SW4, the switch SW5, and the switch SW6 are first controlled to be in an off state, and then the switch SW7 is controlled to be in an on state.

  At this time, the terminal voltage Va at the end point (a) of the resistor R5 is at a level equal to the power supply voltage V1 of the first DC power supply 81.

  Next, the analog switch SW4 provided on the signal line D4 is switched from the off state to the on state (see FIG. 8). When the analog switch SW4 is turned on, as shown by a thick line in FIG. 8, the second DC power supply 82, the resistor R4, the analog switch SW4, the output line Lo, the resistor R5, the resistor R6, and the first DC power supply 81 are closed. (Corresponding to the “diagnostic circuit” of the present invention). In addition, in this embodiment, the values of the power supply voltages V1 and V2 of the first and second DC power supplies 81 and 82 are made different, and the current If flows in the closed circuit.

Thereby, when the output line Lo is not disconnected, the terminal voltage Va at the end point (a) of the resistor R5 becomes the potential of the following expression (3).
Va = [R4 × V1 + (R5 + R6) × V2] / (R4 + R5 + R6) (3)

  On the other hand, when the output line Lo is disconnected in the middle, the current If does not flow in the closed circuit, and the terminal voltage at the end point (a) of the resistor R5 regardless of the ON operation of the switch SW4. Va remains the power supply voltage V 1 of the first DC power supply 81.

  From the above, by monitoring the terminal voltage Va at the end point (a) of the resistor R5 accompanying the ON operation of both the switches SW4, the presence or absence of disconnection of the output line Lo can be diagnosed. Thus, even with the circuit configuration of the second embodiment, the same circuit operation as that of the first embodiment, that is, the detection operation, the failure diagnosis of the analog switches SW1 to SW4, and the disconnection diagnosis of the output line Lo can be performed. It is possible to achieve the effect.

  Further, in this embodiment, since the line voltage of the signal line D4 is taken from the bias line Lv like the other signal lines D1 to D3, the line voltages of all the signal lines D1 to D4 can be set to 2V. With this configuration, since the reference (operating point) of the detection signal is 2 V, the detection signal of each optical axis can be compared in magnitude under the same conditions as the reference voltage Vref of the comparator 70. The presence or absence of a light-shielding object can be accurately detected for the axis.

  In FIG. 4, the detection signal (detection signal after differentiation) of the fourth stage of the optical axis is illustrated as a waveform based on 2 V, similarly to the detection signals of the other stages. Only when a connection is applied, such a waveform is obtained.

<Embodiment 3>
Next, a third embodiment of the present invention will be described with reference to FIGS. In the third embodiment, a part of the circuit configuration is changed from the second embodiment. The change portion will be described with reference to FIG. 9. In this device, the switch SW6 provided in the second embodiment is abolished and the bias line Lv is directly connected to the positive electrode of the first DC power supply 81 and the second DC The positive electrode of the power supply 81 is connected to the input terminal 71 of the comparator 70 via the switch SW7 (corresponding to “diagnostic switching element” of the present invention). In this embodiment, the light reception control circuit 50 is a shift register. Each of the analog switches SW1 to SW4 and the switch SW7 is electrically connected to the shift register 50, and all the five switches SW1 to SW4 and SW7 can be controlled on and off by the shift register 50. .

  In this embodiment as well, the value of the power supply voltage V2 of the second DC power supply 82 is set to a value different from the power supply voltage V1 of the first DC power supply 81, as in the first and second embodiments. . Specifically, the power supply voltage V2 of the second DC power supply 82 is “3V”, and the power supply voltage V1 of the first DC power supply 81 is “2V”.

  If the circuit connection is made in this way, as will be described below, all the switches are first turned off, and then each of the analog switches SW1 to SW4 and the switch SW7 are controlled by the control device 60. Originally, by turning on in the order of SW1, SW2, SW3, SW4, and SW7 by the shift register 50, the disconnection diagnosis of the output line Lo can be performed together with the detection operation for sequentially enabling each optical axis F. This is possible (see FIG. 12). In other words, it is possible to incorporate a disconnection diagnosis of the output line Lo at the end of one detection cycle.

  This is because, as shown in FIG. 10, when the respective analog switches SW1 to SW4 are sequentially turned on, the signal lines D1 to D4 at the respective stages are sequentially energized and output from the light receiving elements PD of the respective optical axes F. The detection signal is output to the comparator 70 through the output line Lo. Therefore, in the same manner as in the first and second embodiments, by monitoring the output of the comparator 70 by the control device 60, it is possible to detect incident light shielding for each optical axis F.

  Then, after the last-stage analog switch SW4 is turned on and the detection signal for the last-stage optical axis F is output to the comparator 70 through the output line Lo, the switch SW7 is then turned on. As shown, the second DC power supply 82, the switch SW7, the output line, the resistor R5, the resistor R6, and the first DC power supply 81 constitute a closed circuit (corresponding to the “diagnostic circuit” of the present invention). In addition, in this embodiment, the values of the power supply voltages V1 and V2 of the first and second DC power supplies 81 and 82 are made different, and the current If flows in the closed circuit.

  Thereby, when the output line Lo is not disconnected, the terminal voltage Va at the end point (a) of the resistor R5 becomes the power supply voltage V2 of the second DC power supply 82.

  On the other hand, when the output line Lo is disconnected in the middle, the current If does not flow in the closed circuit, and the terminal voltage at the end point (a) of the resistor R5 regardless of the ON operation of the switch SW7. Va becomes the power supply voltage V 1 of the first DC power supply 81.

  From the above, by monitoring the terminal voltage Va at the end point (a) of the resistor R5 accompanying the ON operation of the switch SW7, the presence or absence of disconnection of the output line Lo can be diagnosed.

  As described above, according to the configuration of the present embodiment, the disconnection diagnosis of the output line Lo can be performed in conjunction with the detection operation for sequentially enabling each optical axis. Can be detected.

  In this embodiment, the switching elements SW1 to SW4 and SW7 are controlled to be turned on / off by one device (that is, a shift register), so that the on / off control of the switching elements is not complicated. Also, in the above description, “under the control of the control device 60” in the “turning on in the order of SW1, SW2, SW3, SW4, SW7 by the shift register 50 under the control of the control device 60”. The control device 60 side gives a control signal to the shift register 50 at a timing synchronized with the light projection start signal St1 to be given to the light projecting side, and the switches SW1 to SW4 in the off state are given to the shift register 50. This means that the switch on / off control for sequentially turning on the SW 7 is started in accordance with the light projecting operation on the light projecting side.

<Embodiment 4>
Next, a fourth embodiment of the present invention will be described with reference to FIGS. In the fourth embodiment, a part of the circuit configuration is changed from the first embodiment. Referring to FIGS. 13 and 14, the changed portion will be described. In this device, the light receiving element PD, the corresponding analog switch SW, and a part of the output line Lo are unitized as a circuit block B. The circuit blocks B are electrically connected by the connector CN, so that each light receiving element PD is connected in multiple stages.

  More specifically, the first circuit block B1 has a circuit configuration that incorporates all of the circuits on the light receiver 20 side described in the first embodiment except for the resistor R4 and the second DC power supply 82. Four light receiving elements PD1 to PD4, four corresponding light receiving circuits 41 to 44, four analog switches SW1 to SW4, four signal lines D1 to D4, a light receiving control circuit 50, a first DC power supply V1, and a comparator 70 , A control device 60, a part of the bias line Lv, a part of the output line Lo, and the like.

  Similarly to the first circuit block B1, the second circuit block B2 includes four light receiving elements PD11 to PD14, four corresponding light receiving circuits 141 to 144, four analog switches SW11 to SW14, and four signal lines D11 to D14. D14, a light reception control circuit 150, and the like, and the second DC power supply 82 is electrically connected to the signal line D14 via the resistor R14.

  The first circuit block B1 is provided with the first connector CN1, while the second circuit block B2 is provided with the second connector CN2. By fitting the connectors CN1 and CN2 together, FIG. , The bias lines Lv of the first circuit block B1 and the second circuit block B2 are electrically connected to each other, and the output lines Lo of the first circuit block B1 and the second circuit block B2 are electrically connected to each other. Connected to. Further, the light reception control circuit 50 on the first circuit block B1 side and the light reception control circuit 150 on the second circuit block B2 side are electrically connected by a signal line Ls.

  From the above, it becomes possible to apply a bias voltage through the bias line Lv from the first circuit block B1 side to the second circuit block B2 side, and from the second circuit block B2 side, the comparator on the first circuit block B1 side. 70, the detection signal can be input through the output line Lo.

  From the above, similarly to the first embodiment, the switch SW5 on the first circuit block B1 side is turned off, and the analog switches SW1 to SW4 and SW11 to SW14 are set in synchronization with the light projecting timing on the light projecting side. By performing the light projecting / receiving operation that is sequentially turned on, the control device 60 can determine whether light is incident or blocked on all eight optical axes F. Here, although the circuit on the light projecting side is omitted, the light projecting side is also provided with eight light projecting elements as in the light receiving side to form an eight-stage optical axis.

  Further, as shown in FIG. 14, a connection failure between the connectors CN1 and CN2 can be diagnosed by performing the following failure diagnosis at a timing other than the light projecting / receiving operation described above. Specifically, under the control of the control device 60, all the analog switches SW1 to SW4 and SW11 to SW14 are first controlled to be in an off state, and further the switch SW5 is controlled to be in an off state. At this time, the terminal voltage Va at the end point (a) of the resistor R5 is at a level equal to the power supply voltage V1 of the first DC power supply 81.

  Next, the analog switch SW14 on the signal line D14 connected to one end side of the output line Lo that is farthest away from the resistor R5 is controlled to be in an ON state. When the analog switch SW14 is turned on, as shown by a thick line in FIG. 14, the second DC power source 82, the resistor R14, the analog switch SW14, the output line Lo, the resistor R5, the resistor R6, and the first DC power source 81 are closed. (Corresponding to the “diagnostic circuit” of the present invention). In addition, in this embodiment, the values of the power supply voltages V1 and V2 of the first and second DC power supplies 81 and 82 are made different, and the current If flows in the closed circuit.

  Thereby, when the connectors CN1 and CN2 are correctly connected (in other words, when the output line Lo is not disconnected), the terminal voltage Va at the end point (a) of the resistor R5 is the above described in the first embodiment. The potential of the formula (3) is obtained.

  On the other hand, if there is a connection failure between the connectors CN1 and CN2, the current If does not flow in the closed circuit, and the terminal voltage Va at the end point (a) of the resistor R5 is The power supply voltage V1 of the first DC power supply 81 remains unchanged.

  From the above, whether or not the connectors CN1 and CN2 are correctly connected by monitoring the terminal voltage Va at the end point (a) of the resistor R5 with the ON operation of the analog switch SW14 by the control device 60, Easy to diagnose.

  With such a configuration, when the multi-optical axis photoelectric sensor U does not operate normally, if the cause is due to poor connection of the connectors CN1 and CN2, the above diagnosis is performed, and the cause of the failure Therefore, it is not necessary for the operator to visually check the connection state of the connector, and the maintainability is excellent.

  In the fourth embodiment, the bias line Lv, the output line Lo, and the signal line Ls are collectively connected by the common connectors CN1 and CN2. However, each of the lines Lv, Lo, and Ls is dedicated. It is possible to make modifications such as individual connection with the connector.

  In the fourth embodiment, circuit elements such as the resistor R5, the resistor R14, the second DC power supply 82, and the control device 60 necessary for diagnosing the connection state of the connector CN are connected to the circuit block B1 and the circuit block B2. For example, if the resistor R5, the resistor R14, the second DC power supply 82, and the control device 60 are individually arranged for each of the circuit blocks B1 and B2, the output line Lo is arranged. It is also possible to individually diagnose the presence or absence of disconnection for each of the circuit blocks B1 and B2.

  In addition, the method of connecting the connectors CN1 and CN2 to the circuit blocks B1 and B2 is of a type in which the connectors CN1 and CN2 are directly fixed to the circuit board constituting the circuit blocks B1 and B2, and each circuit block. Both of the types in which the connectors CN1 and CN2 are connected to the circuit boards B1 and B2 via cables are applicable.

  In the fourth embodiment, the circuit blocks B1 and B2 include the light receiving element PD, the corresponding light receiving circuit, the corresponding analog switch SW, the corresponding signal line D, and a part of the corresponding output line Lo. Although these are illustrated as a group of four optical axes (that is, four groups), the configuration of the circuit blocks B1 and B2 does not necessarily have to be a group of four optical axes, and other groups, Alternatively, a single set can be used. Further, the circuit blocks B1 and B2 are used in such a manner that they are collectively accommodated in one casing (see FIG. 1 of the first embodiment) 20A, and the circuit blocks B1 and B2 are respectively separate casings. Both types of use accommodated within 20A can be implemented. In the case where the casing is accommodated in one casing 20A, the number of optical axes is naturally increased or decreased within the range of the size of the casing 20A according to the number of connected circuit blocks B1 and B2. In addition, when the circuit blocks B1 and B2 are accommodated in separate casings 20A and used, the number of optical axes is set according to the number of connecting stages of the casings 20A connected in series. Increase / decrease adjustment is possible regardless of the size.

<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.

  (1) In the above embodiment, as an example of the multi-optical axis photoelectric sensor U, a so-called transmissive type arranged corresponding to the light projecting element and the light receiving element is illustrated, but it is of course possible to adopt a so-called reflective type. is there. Here, the reflection type means that both elements are arranged on the same side, while a reflector is installed on the other side, and the reflected light of the light emitted from the light projecting element is received by the light receiving element. .

  (2) Moreover, in the said embodiment, although resistance was illustrated as an example of the "impedance element" of this invention, if it is an element which produces a voltage fluctuation to terminal voltage by electricity supply operation, it is applicable, for example, Variations such as using capacitors instead of resistors are also possible depending on the circuit configuration.

The perspective view which shows the structure of the multi-optical axis photoelectric sensor which concerns on Embodiment 1. FIG. Block diagram showing electrical configuration of multi-optical axis photoelectric sensor Diagram showing circuit operation during detection Waveform diagram of detection signal Diagram showing circuit operation during failure diagnosis of analog switch Diagram showing circuit operation during output line disconnection diagnosis The block diagram which shows the electrical constitution of the multi-optical axis photoelectric sensor which concerns on Embodiment 2. FIG. Diagram showing circuit operation during output line disconnection diagnosis The block diagram which shows the electrical constitution of the multi-optical axis photoelectric sensor which concerns on Embodiment 3. FIG. Diagram showing circuit operation during detection Diagram showing circuit operation during output line disconnection diagnosis Diagram showing the operation timing of each switch The figure which shows the circuit structure of the light receiver which concerns on Embodiment 4 (a connector non-connection state is shown) The figure which similarly shows the circuit configuration of the optical receiver (showing the connector connection state)

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Light projector 20 ... Light receiver (equivalent to the "light receiver for multi-optical axis photoelectric sensors" of this invention)
DESCRIPTION OF SYMBOLS 30 ... Light projection control circuit 41-44 ... Light reception circuit 50 ... Light reception control circuit 60 ... Control apparatus (equivalent to "light projection control means", "light reception control means", "discrimination means", "disconnection diagnostic means" of the present invention) )
70: Comparator 81 ... First DC power supply 82 ... Second DC power supply ("corresponding to diagnostic power supply" of the present invention)
SW1 to SW4... Analog switch (corresponding to “signal switching element” of the present invention)
SW7... Switch (corresponding to “diagnostic switching element” of the present invention)
C1 to C4 ... Capacitors D1 to D4 ... Signal lines R1 to R4 ... Resistors R5 ... Resistors (corresponding to "impedance element" of the present invention)
R6 ... Resistance Lo ... Output line Lv ... Bias line U ... Multi-optical axis photoelectric sensor

Claims (10)

A plurality of light receiving elements;
A plurality of signal-passing switching elements that are connected to the output sides of the plurality of light-receiving elements and pass detection signals output from the respective light-receiving elements on condition that they are turned on;
A light receiving control means for sequentially turning on and off the plurality of signal passing switching elements;
An output line in which the output sides of the plurality of signal passing switching elements are connected in common;
Determining means for determining the light shielding state of each light receiving element based on the level of the detection signal of each light receiving element input through this output line;
A light receiver for a multi-optical axis photoelectric sensor that performs a light receiving operation for detection for detecting the light blocking state for each light receiving element, and determines the light blocking state for each light receiving element by the determining unit,
A diagnostic circuit including the output line, a diagnostic power source connected to one end of the output line via a diagnostic switching element, and an impedance element provided on the other end of the output line;
The level of the terminal voltage of the impedance element when the diagnostic switching element is switched from the OFF state to the ON state and the diagnostic circuit is energized at a timing other than the detection light receiving operation of the light receiving element. A multi-axis photoelectric sensor receiver, comprising: a disconnection diagnosis unit that diagnoses whether or not the output line is disconnected by monitoring.   The plurality of signal passing switching elements and the diagnostic switching element are connected to a shift register, and the control device constituting the light reception control means passes the shift register through the plurality of signal passing switching elements, The multi-axis photoelectric sensor receiver according to claim 1, wherein the diagnostic switching element is sequentially turned on and off.   After a series of light receiving operations, an on / off control procedure of the switching element by the shift register is set in an order of on / off control of the diagnostic switching element after the plurality of signal passing switches are controlled on and off. The multi-optical axis photoelectric sensor receiver according to claim 2, wherein a diagnosis is made as to whether or not the output line is disconnected.   Among the plurality of signal passing switching elements, a switching element connected at a position closest to the one end side with respect to the output line is included in a part of the diagnostic circuit, so that the diagnostic switching is performed. 2. The optical receiver for a multi-optical axis photoelectric sensor according to claim 1, wherein the circuit is configured such that an element is shared by a switching element included in the diagnostic circuit. The light receiving element, the corresponding signal passing switching element, and the output line are unitized as one or a plurality of sets as a circuit block, and ends of the output lines included in the unitized circuit block are connected to each other. By electrically connecting with a connector, the light receiving element is a circuit configuration for connecting the light receiving elements in multiple stages,
The disconnection diagnostic means is configured to cause the impedance element when the diagnostic switching element is energized by switching the diagnostic switching element from an OFF state to an ON state at a timing other than the detection light receiving operation of the light receiving element. 5. The multi-optical axis photoelectric sensor receiver according to claim 1, wherein a connection failure of the connector is detected by monitoring a terminal voltage level of the multi-optical axis photoelectric sensor. A plurality of light emitting elements;
Projection control means for performing projection control for projecting light sequentially at a predetermined timing from the plurality of projection elements;
A plurality of light receiving elements which are provided corresponding to the plurality of light projecting elements to form an optical axis, receive light of the corresponding light projecting elements and output detection signals;
A plurality of signal-passing switching elements that are connected to the output sides of the plurality of light-receiving elements and pass detection signals output from the respective light-receiving elements on condition that they are turned on;
A light receiving control means for controlling on / off of the plurality of signal passing switching elements in order in synchronization with the light projecting timing of the light projecting element;
An output line in which the output sides of the plurality of signal passing switching elements are connected in common;
Discriminating means for discriminating the light shielding state of the optical axis based on the level of the detection signal of each light receiving element input through the output line, and performing light projecting / receiving operation for each optical axis to A multi-optical axis photoelectric sensor for discriminating the shading state of the shaft by the discriminating means,
A diagnostic circuit including the output line, a diagnostic power source connected to one end of the output line via a diagnostic switching element, and an impedance element provided on the other end of the output line;
By monitoring the terminal voltage level of the impedance element when the diagnostic switching element is switched from an off state to an on state and the diagnostic circuit is energized at a timing other than the light projecting / receiving operation, A multi-optical axis photoelectric sensor comprising: a disconnection diagnosis means for diagnosing whether or not the output line is disconnected.   The plurality of signal passing switching elements and the diagnostic switching element are connected to a shift register, and the control device constituting the light reception control means passes the shift register through the plurality of signal passing switching elements, 7. The multi-optical axis photoelectric sensor according to claim 6, wherein the diagnostic switching element is sequentially turned on / off.   By setting the on / off control procedure of the switching element by the shift register to the order in which the diagnostic switching element is controlled to be turned on / off after the plurality of signal passing switches are controlled on and off, a series of light emitting / receiving operations can be performed. The multi-optical axis photoelectric sensor according to claim 7, which is configured to perform a diagnosis on whether or not the output line is disconnected later.   Among the plurality of signal passing switching elements, a switching element connected at a position closest to the one end side with respect to the output line is included in a part of the diagnostic circuit, so that the diagnostic switching is performed. The multi-optical axis photoelectric sensor according to claim 6, wherein the circuit configuration is such that the element is shared by a switching element included in the diagnostic circuit. The light receiving element, the corresponding signal passing switching element, and the output line are unitized as a circuit block for one or a plurality of optical axes, and ends of the output lines included in the unitized circuit block Are connected to each other with a connector to make a multi-optical axis circuit configuration.
The disconnection diagnosis means determines the level of the terminal voltage of the impedance element when the diagnosis switching element is switched from an off state to an on state and the diagnosis circuit is energized at a timing other than the light projecting / receiving operation. The multi-optical axis photoelectric sensor according to claim 6, wherein a connection failure of the connector is detected by monitoring.

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