JP7396198B2 - Multi-channel photoelectric sensor - Google Patents

Description

The present invention relates to multi-channel photoelectric sensors.

2. Description of the Related Art Fiber-type photoelectric sensors are known that use a light-emitting optical fiber and a light-receiving optical fiber that are inserted into and removed from each other. A fiber-type photoelectric sensor detects whether or not the detection light projected onto the light-emitting optical fiber is reflected by the object to be detected and returns to the light-receiving optical fiber, and to what extent. This is a sensor that determines the presence or absence of an object to be detected and its distance. If the object to be detected is made of a light-transmitting material, it is also possible to detect the presence or absence of the object by transmitting detection light and attenuating the amount of light. Among such photoelectric sensors, there is also a multi-channel photoelectric sensor to which a plurality of sets of optical fibers for emitting and receiving light can be connected (see, for example, Patent Document 1).

Japanese Patent Application Publication No. 2004-205209

As an application of a photoelectric sensor compatible with multiple channels, it is assumed that detection targets having some common feature, such as the same target or the same type of target, are detected using each channel. In such a case, if the noise level of the detection signal differs between channels, there will be variations in detection performance between channels, which may cause the user to mistakenly believe that there is a malfunction or require adjustment work for each channel. , other post-processing may be required to suppress variations.

The present invention has been made to solve such problems, and provides a multi-channel photoelectric sensor in which the noise level of detection signals is uniform between channels.

A multi-channel photoelectric sensor according to one aspect of the present invention includes a light receiving element group including a first light receiving element and a second light receiving element, an electromagnetic shielding member that blocks electromagnetic waves directed toward the light receiving element group from the outside, and a light receiving element group. The mounting board includes a connection member that electrically connects the GND wiring of the mounting board and the electromagnetic shielding member, and the connection member is connected from the electrode connection point of the mounting board to which the negative electrode of the first light receiving element is connected. The wiring length of the first GND wiring from the connected member connection point is equal to the wiring length of the second GND wiring from the electrode connection point to which the negative electrode of the second light receiving element is connected to the member connection point to which the connection member is connected. According to the multi-channel photoelectric sensor configured in this way, the difference in noise level of detection signals that may occur between channels can be reduced to a practically negligible level.

In the multi-channel photoelectric sensor described above, the connecting member may be configured to include a first connecting member corresponding to the first light receiving element and a second connecting member corresponding to the second light receiving element. With this configuration, the degree of freedom in designing the mounting board can be improved.

Further, in the above-mentioned multi-channel photoelectric sensor, the electromagnetic shielding member may be a holding member molded from conductive resin and holding the light receiving element group. With this configuration, one element member can have a shielding function and a holding function, which contributes to miniaturization of the photoelectric sensor and simplification of the work process at low cost. At this time, the connection member may be a fixture that fixes the mounting board to the holding member. If the fixture that physically fixes the mounting board and the holding member also serves as the connecting member that electrically connects the two, it will contribute to further simplifying the work process, such as eliminating soldering work.

The above multi-channel photoelectric sensor includes a light emitting element group including a first light emitting element corresponding to the first light receiving element and a second light emitting element corresponding to the second light receiving element, and the light emitting element group includes the above light emitting element group. The wiring length of the third GND wiring, which is mounted on the mounting board, from the electrode connection point to which the negative electrode of the first light emitting element is connected to the member connection point to which the connection member is connected, and the second projection element are mounted on the mounting board. The wiring length of the fourth GND wiring from the electrode connection point to which the negative electrode of the optical element is connected to the member connection point to which the connection member is connected may be configured to be equal. With this configuration, it is possible to make the output levels the same between channels in the light projection system, so it is possible to reduce differences in detection signals between channels when the same target object is detected. In this case, the respective elements may be linearly arranged in the order of the first light projecting element, the first light receiving element, the second light projecting element, and the second light receiving element. When arranged in this way, it is difficult for the user to misunderstand when the user inserts and removes the optical fibers corresponding to the respective elements.

According to the present invention, it is possible to equalize the noise level of detection signals between channels, and to provide a multi-channel photoelectric sensor with less variation in detection performance.

FIG. 1 is an overall perspective view of a photoelectric sensor according to the present embodiment. FIG. 2 is an exploded perspective view showing the main components of the photoelectric sensor. FIG. 2 is an exploded perspective view showing the main components of the sensor unit. FIG. 2 is an overall perspective view of the sensor unit. FIG. 3 is an overall perspective view of the sensor unit from a different perspective. FIG. 3 is a wiring diagram schematically showing GND wiring of the sensor board. FIG. 7 is a wiring diagram schematically showing GND wiring of a sensor board according to a modification.

Embodiments of the present invention will be described with reference to the accompanying drawings. In addition, in each figure, those with the same reference numerals have the same or similar configurations. In addition, in each figure, if there are multiple structures with the same or similar configuration, in order to avoid complication, some are given the reference numerals and others are not given the same reference numerals. There is.

FIG. 1 is an overall perspective view of a photoelectric sensor 100 according to this embodiment. The photoelectric sensor 100 according to the present embodiment is a two-channel optical fiber type photoelectric sensor having two input/output pairs. Specifically, the first channel photoelectric sensor performs detection via the first light receiving fiber 501 and the first light emitting fiber 502, and the detection is performed via the second light receiving fiber 503 and the second light emitting fiber 504. A second channel input/output system is provided for detection.

The first channel determines whether or not the detection light projected to the attached first light-emitting fiber 502 is reflected by the object to be detected and returns to the first light-receiving fiber 502, or to what extent. By detecting this, the presence or absence of the object to be detected and its distance are determined. If the object to be detected is made of a light-transmitting material, it is also possible to detect the presence or absence of the object by transmitting detection light and attenuating the amount of light. Similarly, the second channel uses the second light-receiving fiber 503 and the second light-emitting fiber 504 to determine the presence or absence of the object to be detected and the distance thereof. The objects to be detected in the first channel and the second channel may be different objects, or may be objects that have something in common, such as the same object or the same type of object.

The photoelectric sensor 100 has a flat box shape as a whole, and mainly consists of a housing 190 and an opening/closing cover 110 that covers the upper part of the housing 190 in an openable/closable manner. The housing 190 has four holes on the distal end side. Specifically, the first lower insertion hole 191 is used to insert and remove the first light receiving fiber 501, the first upper insertion hole 192 is used to insert and remove the first light emitting fiber 502, and the second light receiving fiber 503 is inserted and removed. It has a second lower insertion hole 193 for inserting and removing the second light emitting fiber 504, and a second upper insertion hole 194 for inserting and removing the second light emitting fiber 504.

When the user opens the opening/closing cover 110, the user can operate the push buttons housed inside. Further, the open/close cover 110 is made of a transparent material, and the user can visually confirm the information presented by the display section housed inside even when the open/close cover 110 is in a closed state.

When using the first channel, the first light receiving fiber 501 is inserted into the first lower insertion hole 191 and fixed, and the first light emitting fiber 502 is inserted into the first upper insertion hole 192 and fixed. Similarly, when using the second channel, the second light receiving fiber 503 is inserted into the second lower insertion hole 193 and fixed, and the second light emitting fiber 504 is inserted into the second upper insertion hole 194 and fixed. Ru. Note that the photoelectric sensor 100 can function only one of the first channel and the second channel, or can function both at the same time. However, the subsequent processing circuit that is responsible for both the first channel signal processing and the second channel signal processing sequentially executes each signal processing.

The housing 190 has a receiving part for the connector unit 160 on the rear end side, and the figure shows the state in which the connector unit 160 is attached to the receiving part. The connector unit 160 is provided at one end of the cable 161 and connects the power line and signal line included in the cable 161 to the circuit board inside the casing 190.

Note that the x-axis, y-axis, and z-axis are defined as shown in the figure. In the subsequent drawings, the same coordinate axes as in FIG. 1 are also used to indicate the orientation of the structure represented by each drawing. In the following description, as mentioned above, the positive direction of the z-axis is upward, the negative direction is downward, the negative side of the x-axis is the tip side, the positive side is the rear end, the positive side of the z-axis is the upper side, The negative side may be referred to as the lower side, the direction along the x-axis as the longitudinal direction, the direction along the y-axis as the short-side direction, and the direction along the z-axis as the height direction.

FIG. 2 is an exploded perspective view showing the main components of the photoelectric sensor 100. The photoelectric sensor 100 mainly includes an open/close cover 110, a UI unit 200, a base frame 140, a sensor unit 150, a connector unit 160, a main board 170, a shield plate 180, and a housing 190. The housing 190 has an opening 195 on the upper side. That is, the internal space of the housing 190 is wide open upward. The UI unit 200, base frame 140, sensor unit 150, main board 170, and shield plate 180 are assembled and housed in the internal space of the housing 190 through the opening 195. The opening/closing cover 110 closes the opening 195. Furthermore, the connector unit 160 is attached to the housing 190 from the rear end side.

The UI unit 200 mainly includes a mask sheet 121, a shading pad 122, a button pad 123, and a sub-board 130. The sub-board 130 is a rigid plate-shaped hard board also called a rigid board.

The button pad 123 is a rubber molded sheet in which a key top and a base in contact with the mounting surface of the sub-board 130 are integrally formed. The shading pad 122 is a light shielding plate disposed on the mounting surface of the sub-board 130 and provided with through-holes corresponding to the LEDs for presenting information and the button pads 123 mounted on the sub-board 130 . The mask sheet 121 is a sheet on which are printed a transparent window frame that defines the outline of the light from the LED for presenting information, and characters and icons that explain the roles of the push buttons.

The base frame 140 forms the skeleton of the photoelectric sensor 100, and is molded from a thick resin so as not to easily deform. The base frame 140 has an L-shape as a whole as shown, and serves as a base material to which the openable cover 110, the UI unit 200, the sensor unit 150, the main board 170, and the shield plate 180 are attached.

The sensor unit 150 includes a fixing mechanism that fixes the sensor substrate on which the light emitting/receiving elements of each channel are mounted and the optical fiber inserted therethrough. Specifically, this will be explained in detail later. The connector unit 160 connects the power line and signal line contained in the cable 161 to corresponding terminals of the main board 170. Note that the connector unit 160 may be configured to be detachable from the housing 190.

The main board 170 is a circuit board on which many various elements that make the photoelectric sensor 100 function are mounted. The main board 170 is also a hard board like the sub board 130. The shield plate 180 is an electromagnetic shield plate that blocks electromagnetic waves directed toward the main board 170 from the outside, and is formed by bending a copper plate, for example. The shield plate 180 has a U-shape when viewed from the longitudinal direction, and has an area that alone covers most of both mounting surfaces of the main board 170.

FIG. 3 is an exploded perspective view showing the main components of the sensor unit 150. The sensor unit 150 mainly includes a slider 210, a fiber gripper 220, a holder 230, a lever 240, a light emitting/receiving element group 250, a sensor substrate 260, and a connecting member 270.

The slider 210, fiber gripper 220, and lever 240 constitute a fixing mechanism that fixes the inserted optical fiber. The slider 210 is arranged on the distal end side of the holder 230. The lever 240 is attached to the upper part of the holder 230 via a hinge pin 241 so that it can rotate within a certain angle range. Further, the lever 240 and the slider 210 are connected to each other via a link mechanism, and the slider 210 is displaced in the vertical direction in response to opening and closing of the lever 240. The fiber gripper 220 includes a first gripper 221 that fixes the first light receiving fiber 501 and the first light emitting fiber 502, and a second gripper 222 that fixes the second light receiving fiber 503 and the second light emitting fiber 504. include.

The holder 230 functions as a holding member that holds the light emitting/receiving element group 250. Specifically, the holder 230 has a fitting hole that matches the outer peripheral shape of each light emitting/receiving element, and each light emitting/receiving element is positioned and held in the holder 230 by being fitted into the fitting hole. The holder 230 is molded from a conductive resin in which a conductive filler is embedded, and the entirety thereof is kept at ground potential. Therefore, the holder 230 functions as an electromagnetic shielding member that blocks electromagnetic waves directed toward the light emitting/receiving element group 250 from the outside.

The light emitting/receiving element group 250 includes a first light receiving PD 251 and a first light emitting LED 252 forming a first channel, and a second light receiving PD 253 and a second light emitting LED 254 forming a second channel. The detection light emitted from the first light emitting LED 252 is projected onto the object to be detected via the first light emitting fiber 502, and the detection light reflected from the object is transmitted to the first light receiving fiber 501 via the first light receiving fiber 501. The light is received by the light receiving PD 251 and converted into an electrical signal. The converted electrical signal is sent to the processing circuit as a first detection signal. Similarly, the detection light emitted from the second light emitting LED 254 is projected onto the object to be detected via the second light emitting fiber 504, and the detection light reflected from the object is reflected via the second light receiving fiber 503. The light is received by the second light receiving PD 253 and converted into an electrical signal. The converted electrical signal is sent to the processing circuit as a second detection signal.

The first light shielding plate 255 is a light shielding plate that blocks light leaking from the rear surface of the first light emitting LED 252 from entering the first light receiving PD 251 and the second light receiving PD 253 as stray light. It is attached to the first light receiving PD 251. Similarly, the second light shielding plate 256 is a light shielding plate that prevents light leaking from the rear surface of the second light emitting LED 254 from entering the first light receiving PD 251 and the second light receiving PD 253 as stray light. It is passed through and attached to the second light receiving PD 253.

The sensor board 260 is a mounting board on which the light emitting/receiving element group 250 is mounted, and is a hard board like the main board 170 and the sub board 130. Each of the light emitting/receiving element groups 250 is soldered to the mounting surface so that its light emitting part or light receiving part protrudes from the sensor board toward the tip side. The sensor board 260 is equipped with a driver circuit that makes the first light projection LED 252 and the second light projection LED 254 flicker in accordance with a control signal from a CPU (not shown). Further, a preamplifier circuit is installed to amplify the first detection signal and the second detection signal photoelectrically converted by the first light receiving PD 251 and the second light receiving PD 253. The sensor board 260 is electrically connected to the main board 170 and transmits and receives control signals and detection signals to and from the main board 170.

The connecting member 270 is a fixture for fixing the sensor board 260 to the holder 230 and includes a first screw 271 and a second screw 272. The first screw 271 passes through a notch 261 provided in the sensor board 260 and is fastened to a prepared hole (not shown) provided in the holder 230. The second screw 272 passes through the through hole 262 provided in the sensor board 260 and is fastened to a prepared hole (not shown) provided in the holder 230. The first screw 271 and the second screw 272 are both highly conductive metal screws.

FIG. 4 is an overall perspective view of the sensor unit 150 in an assembled state. The first gripper 221 has a C-ring part 221a that sandwiches and fixes the tip of the first light-receiving fiber 501, and a C-ring part 221b that sandwiches and fixes the tip of the first light-emitting fiber 502. The second gripper 222 has a C-ring part 222a that sandwiches and fixes the tip of the second light-receiving fiber 503, and a C-ring part 222b that sandwiches and fixes the tip of the second light-emitting fiber 504. When the lever 240 is rotated from the open position to the lock position shown, the slider 210 slides downward with respect to the holder 230. At this time, the slider 210 pushes down the C-ring parts 221a, 221b, 222a, and 222b to narrow the inner diameter. If an optical fiber is inserted through the C-ring, the optical fiber will be pressed and fixed by the C-ring.

Specifically, the end face of the fixed first light-receiving fiber 501 faces the first light-receiving PD 251, and the end face of the first light-emitting fiber 502, which is also fixed, faces the first light-emitting LED 252. Similarly, the end face of the fixed second light-receiving fiber 503 faces the second light-receiving PD 253, and the end face of the fixed second light-emitting fiber 504 faces the second light-emitting LED 254.

FIG. 5 is an overall perspective view of the sensor unit 150 from a different perspective. The sensor board 260 is fixed to the rear end side of the holder 230 by a first screw 271 and a second screw 272. The two electrode pins of the positive electrode and the negative electrode in each of the light emitting/receiving element group 250 penetrate the sensor board 260 at their tips and are soldered to the corresponding lands, respectively. For example, focusing on the respective negative electrode pins, as shown in the figure, from the bottom to the top, the negative electrode pin 251a of the first light receiving PD 251, the negative electrode pin 252a of the first light emitting LED 252, the negative electrode pin 253a of the second light receiving PD 253, the second Negative pins 254a of the light emitting LEDs 254 are arranged.

Now, the photoelectric sensor 100 in this embodiment is equipped with a two-channel input/output system as described above, but the main use of such a photoelectric sensor is to detect two objects that have some common properties. It is assumed that the channels are detected in parallel. In such a case, if the noise level of the detection signal differs between channels, the user may be misled into thinking that there is a failure, or post-processing based on the channel with poor performance may be required.

Differences in noise level between channels occur due to various elements of elements and circuits, and one of the main factors is a difference in GND wiring length on a circuit board. FIG. 6 is a wiring diagram schematically showing GND wiring provided on the sensor substrate 260 of the photoelectric sensor 100 according to this embodiment.

The first PD negative land 351 is a land (electrode connection point) to which the negative pin 251a of the first light receiving PD 251 is soldered. Similarly, the second PD negative land 353 is a land (electrode connection point) to which the negative pin 253a of the second light receiving PD 253 is soldered.

On the other hand, a first screw land 371 serving as a screw member connection point is provided around the notch 261 into which the first screw 271 is inserted. The first screw land 371 comes into contact with the head of the first screw 271 when the first screw 271 is fastened to the holder 230 with the sensor board 260 interposed therebetween. The first screw 271 has a wider cross-sectional area and much lower electrical resistance than the wiring on the sensor board 260, so the first screw land 371 connects the holder 230 shaped with conductive resin via the first screw 271. It is maintained at substantially the same potential as the ground potential. Further, a second screw land 372 as a screw member connection point is provided around the through hole 262 through which the second screw 272 is inserted. The second screw land 372 contacts the head of the second screw 272 when the second screw 272 is fastened to the holder 230 with the sensor board 260 interposed therebetween. Since the second screw 272 has a wider cross-sectional area and a much lower electrical resistance than the wiring on the sensor board 260, the second screw land 372 is attached to the holder 230 shaped with conductive resin through the second screw 272. It is maintained at substantially the same potential as the ground potential. That is, the first screw land 371 and the second screw land 372 are both kept at the ground potential when the sensor board 260 is fixed to the holder 230 by the first screw 271 and the second screw 272.

The first GND wiring 311 is a GND wiring that connects the first PD negative land 351 and the first screw land 371. Further, the second GND wiring 312 is a GND wiring that connects the second PD negative land 353 and the second screw land 372. In this embodiment, the wiring length of the first GND wiring 311 and the wiring length of the second GND wiring 312 are set to be equal to each other. As mentioned above, the first screw land 371 and the second screw land 372 have substantially the same potential, so by making these wiring lengths the same, the difference in noise level between the first detection signal and the second detection signal can be practically reduced. It has been reduced to a negligible level.

The first LED negative land 352 is a land (electrode connection point) to which the negative pin 252a of the first LED 252 is soldered. Similarly, the second LED negative land 354 is a land (electrode connection point) to which the negative pin 254a of the second light emitting LED 254 is soldered.

The third GND wiring 313 is a GND wiring that connects the first LED negative land 352 and the first screw land 371. Further, the fourth GND wiring 314 is a GND wiring that connects the second LED negative land 354 and the second screw land 372. In this embodiment, the wiring length of the third GND wiring 313 and the wiring length of the fourth GND wiring 314 are set to be equal to each other. As mentioned above, the first screw land 371 and the second screw land 372 have substantially the same potential, so by making these wiring lengths the same, variations in the output level of each detection light due to the difference in wiring length can be reduced. It is being reduced. Furthermore, the difference between the first detection signal and the second detection signal when the same target object is detected is reduced.

Note that the illustrated GND wiring schematically shows an example, and the specific wiring pattern is not limited to the illustrated example. If a multilayer substrate is employed as the sensor substrate 260, the GND wiring may be provided in an intermediate layer or may be provided across a plurality of layers. In addition, GND wiring provided on the same board is generally realized with the same width and conductive material, so the explanation focused on the wiring length, but when the width and conductive material are different between the GND wiring For this purpose, the impedances of the respective GND wirings may be adjusted to be equal to each other.

In the present embodiment described above, the first screw 271 corresponding to the first light receiving PD 251 and the second screw 272 corresponding to the second light receiving PD 253 are used as connection members for electrically connecting with the holder 230. Established. With this configuration, the degree of freedom in designing the mounting board is improved. One of the benefits is that the first light receiving PD 251, the first light emitting LED 252, the second light receiving PD 253, and the second light emitting LED 254 are arranged linearly in this order from the bottom to the top. This arrangement creates a regularity in which the light-receiving system is on the bottom and the light-emitting system is on the top in each channel. Especially in the photoelectric sensor 100 where the user inserts and removes the optical fiber, the user interface is placed in order to prevent incorrect installation. Very desirable.

However, the number of screws serving as connection members for electrically connecting to the holder 230 may be combined into one. FIG. 7 is a wiring diagram schematically showing GND wiring of a sensor board 260' according to a modification. The sensor board 260' differs from the sensor board 260 in that it is electrically connected to the holder 230 only by the first screw 271.

Therefore, the negative pin 251a of the first light receiving PD 251, the negative pin 252a of the first light emitting LED 252, the negative pin 253a of the second light receiving PD 253, and the negative pin 254a of the second light emitting LED 254 are all electrically connected to the first screw land 371. Needs to be connected. Therefore, in this modification, the arrangement of the first light-receiving PD 251 and the first light-emitting LED 252 remains the same, but the arrangement of the second light-receiving PD 253 and the second light-emitting LED 254 is changed. That is, focusing on the respective negative electrode pins, from the bottom to the top, the negative electrode pin 251a of the first light receiving PD 251, the negative electrode pin 252a of the first light emitting LED 252, the negative electrode pin 254a of the second light emitting LED 254, and the negative electrode pin 254a of the second light receiving PD 253. Negative electrode pins 253a are arranged. Corresponding to these negative electrode pins, a first PD negative land 351, a first LED negative land 352, a second LED negative land 354', and a second PD negative land 353 are provided on the sensor substrate 260' from the bottom to the top. .

By adopting such an arrangement, the wiring length of the first GND wiring 311 connecting the first PD negative land 351 and the first screw land 371 and the second GND wiring 312 connecting the second PD negative land 353' and the first screw land 371 can be changed. 'The wiring lengths are made equal. Similarly, the wiring length of the third GND wiring 313 that connects the first LED negative land 352 and the first screw land 371, and the wiring length of the fourth GND wiring 314' that connects the second LED negative land 354' and the first screw land 371. are made equal. Note that the third GND wiring 313 and the fourth GND wiring 314' share a part. In this way, the corresponding GND wirings may be wirings that share a portion with each other.

Adopting such a sensor board 260' contributes to reducing the number of parts and simplifying the work process. Note that in both the wiring example of the sensor board 260 and the wiring example of the sensor board 260' described above, the wiring length of the third wiring and the wiring length of the fourth wiring are equal to each other, but at least the wiring length of the first wiring and the wiring length of the fourth wiring are equal to each other. It does not matter if the wiring lengths of the second wirings are equal to each other. If the wiring length of the first wiring and the wiring length of the second wiring are equal to each other, the noise level of the detection signal will be the same between channels to some extent, so it will not cause the user to misunderstand that there is a failure, or the subsequent stage will use the channel with poor performance as the reference. No processing is required.

Furthermore, in the present embodiment described above, the holder 230 holding the light emitting/receiving element group 250 is shaped with conductive resin to serve as an electromagnetic shielding member that blocks electromagnetic waves directed toward the light emitting/receiving element group 250 from the outside. With this configuration, one element member can have a shielding function and a holding function, which contributes to miniaturization of the photoelectric sensor 100 and simplification of the work process. However, if the shield plate 180 also wraps around the sensor unit 150, for example, the shield plate 180 can be used as an electromagnetic shielding member that blocks electromagnetic waves directed toward the light emitting/receiving element group 250 from the outside. In this case, the holder 230 does not need to be made of conductive resin, and the GND wiring of the sensor board 260 may be connected to the shield plate 180 via a connecting member.

Furthermore, in the present embodiment described above, screws are used as the connecting members, but the connecting members are not limited to screws. Any fixture may be used as long as it is made of a conductive material. If the fixture that physically fixes the sensor board 260, which is a mounting board, and the holder 230, which is a holding member, also serves as a connecting member that electrically connects the two, the work process can be further improved, such as by omitting soldering work. Contribute to simplification. Alternatively, for example, a metal piece provided on the holder 230 and a connection land on the sensor board 260 may be directly connected by solder. In this case, the metal piece and solder provided on the holder 230 serve as a connecting member. Note that the fixing member and the connecting member may be separately prepared as a fixing member and a connecting member, respectively. In particular, when using solder as the connecting member, it is advisable to prepare a fixing member separately.

Moreover, although the photoelectric sensor 100 in this embodiment described above is provided with an input/output system of two channels, it may be provided with an input/output system with a larger number of channels. When three or more input/output systems are provided, even if the GND wiring lengths from the electrode land to which the negative electrode of each light-receiving PD is connected to the member land to which the connection member is connected are all set to be equal. Often, some of them may be set to be equal. For example, if a three-channel input/output system is provided, two of which are for short-distance detection and the remaining one is for long-distance detection, the GND wiring length will be different for the two channels for short-distance detection. It is sufficient if they are set to be equal.

[Additional note 1]
A light receiving element group including a first light receiving element (251) and a second light receiving element (253);
an electromagnetic shielding member (230) that blocks electromagnetic waves directed from the outside toward the light receiving element group;
a mounting board (260) on which the light receiving element group is mounted;
A connection member (271, 272) that electrically connects the GND wiring (311, 312) of the mounting board (260) and the electromagnetic shielding member (230),
From the electrode connection point (351) of the mounting board (260) to which the negative electrode (251a) of the first light receiving element (251) is connected to the member connection point (371) to which the connection member (271) is connected. The wiring length of the first GND wiring (311) and the member connection point to which the connection member (272) is connected from the electrode connection point (353) to which the negative electrode (253a) of the second light receiving element (253) is connected. A multi-channel photoelectric sensor (100) in which the second GND wiring (312) up to (372) has the same wiring length.

DESCRIPTION OF SYMBOLS 100... Photoelectric sensor, 110... Opening/closing cover, 121... Mask sheet, 122... Shading pad, 123... Button pad, 130... Sub board, 140... Base frame, 150... Sensor unit, 160... Connector unit, 161... Cable, 170 ...Main board, 180... Shield plate, 190... Housing, 191... First lower insertion hole, 192... First upper insertion hole, 193... Second lower insertion hole, 194... Second upper insertion hole, 195... Opening , 200...UI unit, 210...Slider, 220...Fiber gripper, 221...First gripper, 221a, 221b...C ring section, 222...Second gripper, 222a, 222b...C ring section, 230...Holder, 240...Lever , 241... Hinge pin, 250... Light emitting/receiving element group, 251... First light receiving PD, 251a... Negative electrode pin, 252... First light emitting LED, 252a... Negative electrode pin, 253... Second light receiving PD, 253a... Negative electrode pin, 254 ...Second light emitting LED, 254a...Negative electrode pin, 255...First light shielding plate, 256...Second light shielding plate, 260, 260'...Sensor board, 261...Notch, 262...Through hole, 270...Connecting member, 271 ...First screw, 272...Second screw, 311...First GND wiring, 312, 312'...Second GND wiring, 313...Third GND wiring, 314, 314'...Fourth GND wiring, 351...First PD negative land, 352... 1st LED negative electrode land, 353, 353'... 2nd PD negative electrode land, 354, 354'... 2nd LED negative electrode land, 371... 1st screw land, 372... 2nd screw land, 501... 1st light receiving fiber, 502... 1st throw Optical fiber, 503...second light receiving fiber, 504...second light emitting fiber

Claims (6)

a light receiving element group including a first light receiving element and a second light receiving element;
an electromagnetic shielding member that blocks electromagnetic waves directed from the outside toward the light receiving element group;
a mounting board on which the light receiving element group is mounted;
comprising a connecting member that electrically connects the GND wiring of the mounting board and the electromagnetic shielding member,
The wiring length of the first GND wiring from the electrode connection point to which the negative electrode of the first light receiving element is connected to the member connection point to which the connection member is connected on the mounting board, and the negative electrode of the second light receiving element are A multi-channel photoelectric sensor in which the wiring length of the second GND wiring from the connected electrode connection point to the member connection point to which the connection member is connected is equal. The multi-channel photoelectric sensor according to claim 1, wherein the connecting member includes a first connecting member corresponding to the first light receiving element and a second connecting member corresponding to the second light receiving element. 3. The multi-channel photoelectric sensor according to claim 1, wherein the electromagnetic shielding member is a holding member molded from conductive resin and holding the light receiving element group. The multi-channel photoelectric sensor according to claim 3, wherein the connecting member is a fixture that fixes the mounting board to the holding member. comprising a light projecting element group including a first light projecting element corresponding to the first light receiving element and a second light projecting element corresponding to the second light receiving element,
The light emitting element group is mounted on the mounting board,
The wiring length of the third GND wiring from the electrode connection point to which the negative electrode of the first light emitting element is connected to the member connection point to which the connection member is connected on the mounting board, and the negative electrode of the second light emitting element. 5. The multi-channel photoelectric sensor according to claim 1, wherein the fourth GND wiring has the same wiring length from the electrode connection point to which the electrode is connected to the member connection point to which the connection member is connected. The multi-channel photoelectric sensor according to claim 5, wherein the first light emitting element, the first light receiving element, the second light emitting element, and the second light receiving element are arranged linearly in this order.