JP2016031338A - Photoelectric sensor and method for manufacturing photoelectric sensor - Google Patents

Abstract

A photoelectric sensor having excellent water resistance is provided.
A light emitting element and a light receiving element for detecting an object to be detected, and a circuit board having a control circuit for outputting a detection signal when the object to be detected is detected based on the operation of the light projecting element and the light receiving element; Is formed so as to cover the frame members 9, 20, and 21 that respectively hold the light projecting element, the light receiving element, and the circuit board, a cover member that covers the frame member, and the frame member and the cover member. The frame member, the cover member, and the case were molded from a thermoplastic resin.
[Selection] Figure 5

Description

  The present invention relates to a photoelectric sensor.

  The photoelectric sensor is provided with the light projecting unit and the light receiving unit facing each other, and detects the detected object when detection light such as infrared rays output from the light projecting unit toward the light receiving unit is blocked by the detected object. It is possible.

  As a type of photoelectric sensor, a detection signal is output by a light projecting unit equipped with a light projecting element, a light receiving unit equipped with a light receiving element, control of the output operation of detection light from the light projecting unit, and light receiving operation in the light receiving unit. Some have a circuit board equipped with a control circuit that generates and outputs a detection signal to a control system that controls the position of the detected portion.

  In a control system in which such a photoelectric sensor is installed, the system may be cleaned by jetting cleaning water. For this reason, it is necessary to ensure required water resistance for the photoelectric sensor.

  Patent Document 1 discloses a photosensor in which an amplifier part is molded with resin and further accommodated in a case.

Japanese Patent Laid-Open No. 11-145505

  In the photosensor disclosed in Patent Document 1, the amplifier unit is molded with resin and has water resistance. However, the terminals of the amplifier unit, the light projecting unit, and the leads that connect the light receiving unit and the amplifier unit must be molded. Not in.

Therefore, when the cleaning water enters the case, there is a problem that the lead or the terminal of the amplifier unit is short-circuited and the photosensor does not operate normally.
The present invention has been made in view of such circumstances, and an object thereof is to provide a photoelectric sensor having excellent water resistance.

  A photoelectric sensor that solves the above problems includes a light projecting element and a light receiving element that detect a detected object, and a control that outputs a detection signal when the detected object is detected based on the operation of the light projecting element and the light receiving element. In a photoelectric sensor in which a circuit board on which a circuit is mounted is housed in a case, a frame member that respectively holds the light projecting element, the light receiving element, and the circuit board, a cover member that covers the frame member, and the frame member and cover And a case molded so as to cover the member, wherein the frame member, the cover member, and the case are molded of a thermoplastic resin.

With this configuration, the interface between the case, the frame member, and the cover member melts to improve water tightness.
The photoelectric sensor preferably includes a space between the circuit element mounting surface of the circuit board and the cover member.

With this configuration, the thermal stress applied to the circuit elements on the circuit board is reduced when the case is molded.
In the photoelectric sensor, the light projecting element, the light receiving element, the circuit board is mounted on a metal frame, a frame member that holds the light projecting element, and a frame member that holds the light receiving element; A frame member for holding the circuit board is formed on a metal frame, the metal frame is bent, and a frame member for holding the light projecting element and a frame member for holding the light receiving element are held by the circuit board. The cover member was suspended from both sides of the frame member, and the cover member was integrally molded so as to cover each frame member.

With this configuration, each frame member is covered with the cover member when the case is molded.
In the photoelectric sensor, it is preferable that the wiring connected to the circuit board is covered with a covering member, and the case is formed so that the wiring covered with the covering member is exposed from the case.

With this configuration, water tightness between the case and the wiring is improved.
In addition, a photoelectric sensor manufacturing method that solves the above-described problems includes a light projecting element frame that includes a light projecting element, a light receiving element, a terminal that connects a circuit board and wiring, and a terminal that holds the light projecting element. A light receiving element frame that holds the light receiving element, a base member that holds the circuit board, and a terminal member that holds the terminal are formed of a thermoplastic resin on the metal frame, and the light projecting element and the light receiving element And a metal frame that electrically connects the circuit board and the light projecting element and the light receiving element are opposed to each other, and a cover member formed of a thermoplastic resin is attached to the light projecting element frame, the light receiving element frame, and the base member. A thermoplastic resin case is formed to cover the light projecting element frame, the light receiving element frame, the base member, and the terminal member.

  With this configuration, the interface between the case, the frame member, and the cover member melts to improve water tightness.

  According to the photoelectric sensor of the present invention, the water resistance of the photoelectric sensor can be improved.

It is a perspective view which shows a photoelectric sensor. It is a perspective view which shows the principal part of a photoelectric sensor. It is a perspective view which shows a cover member. It is a perspective view which shows a cover member. It is a perspective view which shows the state which attached the cover member to the principal part. It is a perspective view which shows the state which attached the cover member to the principal part. It is a front view which shows the state which attached the cover member to the principal part. It is sectional drawing which shows the state which attached the cover member to the principal part. It is sectional drawing which shows a board | substrate cover.

  Hereinafter, an embodiment of a photoelectric sensor will be described with reference to the drawings. The photoelectric sensor shown in FIG. 1 has a mounting piece 2 formed on one side of a case 1 integrally formed of a thermoplastic resin, and two mounting holes 3 are formed in the mounting piece 2 in the vertical direction. And an attachment screw etc. can be inserted in the attachment hole 3, and it can fix to a predetermined attachment position. In this embodiment, the case 1 is formed of PBT (polybutylene terephthalate), and the strength that can prevent the occurrence of buckling during screwing is ensured.

  On the upper surface of the case 1, the light projecting unit 4 and the light receiving unit 5 are extended upward so as to face each other with a predetermined interval. A light projecting element is built in the light projecting unit 4, and a light receiving element is built in the light receiving unit 5, and infrared light output from the light projecting element is passed through the light projecting unit 4 and the outer frame of the light receiving unit 5. The light receiving element can receive light.

Next, the main part of the photoelectric sensor housed in the case 1 will be described.
The main part M shown in FIG. 2 forms a resin frame with PBT on the circuit board 6, the light projecting element 7, the light receiving element 8, and the like electrically connected on the lead frame, and appropriately bends the resin frame. Is formed.

  On the circuit board 6, a control circuit composed of an IC chip and passive elements such as resistors and capacitors and a light emitting element 25 are mounted. A base member 9 having a square frame shape is formed so as to surround the circuit board 6, thereby forming a board portion 10.

  A light projecting element frame 11 is suspended from one side of the substrate portion 10 in the longitudinal direction, and a light receiving element frame 12 is suspended from the other side in the longitudinal direction. The light projecting element frame 11 is a resin frame that protects the light projecting element 7, and the light receiving element frame 12 is a resin frame that protects the light receiving element 8.

  In a state where the light projecting element frame 11 and the light receiving element frame 12 are vertically bent and bent at the lead portion between the light projecting element frame 11 and the light receiving element frame 12 and the base member 9, the light projecting element 7 and the light receiving element are received. The elements 8 are adapted to face each other.

  The reinforcing portion 13 and the terminal member 14 connected to the base member 9 via leads are bent so as to go around the back surface of the base member 9 at the lead portions. As shown in FIGS. 6 and 7, the ends of the wires 16a to 16d, which are stripped from the coating of the wirings 16a to 16d, are joined to the four terminals 15a to 15d exposed on the back surface of the terminal member by soldering or the like. The wirings 16a to 16d are power supply wirings and signal lines, and are collectively covered with the covering member 17 up to just below the terminal member 14.

  FIG. 3 shows a cover member 18 attached so as to cover the substrate portion 10, the light projecting element frame 11 and the light receiving element frame 12 prior to the molding of the case 1. The cover member 18 is molded in two colors using a thermoplastic resin that can transmit visible light and a thermoplastic resin that does not transmit visible light. In this embodiment, the cover member 18 is formed of PC (polycarbonate).

  A substrate cover 19 formed in a lid shape mainly covering the upper surface of the substrate portion 10 is formed of a red resin, and is vertically suspended at both ends in the longitudinal direction of the substrate cover 19, and mainly the light projecting element frame 11. The frame covers 20 and 21 that cover the opposing surfaces of the light receiving element frame 12 are formed of black resin.

  As shown in FIG. 4, a frame-shaped portion 22 that can be fitted to the outer peripheral portion of the base member 9 is formed on the outer peripheral portion of the back surface of the substrate cover 19. Further, inside the frame-shaped portion 22, a large number of projections and depressions 23 having a cross-sectional waveform are formed on the back surface of the substrate cover 19 along the longitudinal direction of the substrate cover 19, as shown in FIG. 9.

When the substrate cover 19 of such a cover member 18 is fitted to the base member 9, the facing surfaces of the light projecting element frame 11 and the light receiving element frame 12 are covered with the frame covers 20 and 21 as shown in FIG.
As shown in FIG. 8, a space 24 is secured between the circuit element mounting surface of the circuit board 6 and the lower surface of the substrate cover 19.

  As described above, the cover member 18 is set on the mold in a state where the cover member 18 is attached to the substrate unit 10, the light projecting element frame 11 and the light receiving element frame 12, and the case 1 is mounted with the upper surface and side surfaces of the substrate cover 19 exposed. Mold. Then, as shown in FIG. 1, a photoelectric sensor is formed in which the substrate portion 10, the light projecting element frame 11, the light receiving element frame 12, and the frame covers 20 and 21 are covered with the case 1 except for the substrate cover 19. At this time, the wirings 16 a to 16 d are exposed from the case 1 at a portion covered with the covering member 17, and the covering member 17 is held in a state having water tightness with respect to the case 1.

Next, the operation of the photoelectric sensor configured as described above will be described.
In this photoelectric sensor, except for the upper surface and side surface of the substrate cover 19, the substrate portion 10, the light projecting element frame 11, the light receiving element frame 12, the wirings 16 a to 16 d, and the leads connecting them are the case 1 and the substrate cover 19. Covered.

  Since the case 1 molded with PBT, the base member 9, the substrate portion 10, the reinforcing portion 13, the terminal member 14, and the cover member 18 molded with PC are all made of thermoplastic resin, the case 1 is molded when the case 1 is molded. The interface between 1 and another member melts to improve water tightness.

  When the case 1 is molded, a space 24 is secured between the substrate cover 19 and the circuit board 6 in the substrate unit 10. For this reason, since PBT does not flow onto the circuit board 6 when the case 1 is molded, the thermal stress acting on the circuit elements is reduced.

  In the installed state, when the detected object passes between the light projecting unit 4 and the light receiving unit 5, infrared light output from the light projecting element toward the light receiving element is blocked by the detected object. Then, the control circuit mounted on the substrate unit 10 detects the passage of the object to be detected, outputs the detection signal to the control system connected by the wirings 16a to 16d, and turns on the light emitting element 25.

  When the light emitting element 25 is turned on, the visible light is scattered by the unevenness 23 on the back surface of the substrate cover 19 and passes through the substrate cover 19. Then, since scattered light is radiated from the upper surface and the side surface of the substrate cover 19, almost the entire substrate cover 19 is lit in red.

In the photoelectric sensor as described above, the following effects can be obtained.
(1) A case made of PBT so as to substantially cover the base member 9, the substrate portion 10, the reinforcing portion 13, the terminal member 14, and the cover member 18 formed of thermoplastic resin PC, which are molded from a thermoplastic resin PBT. Since 1 is molded, when the case 1 is molded, the interface between the case 1 and other members melts to improve water tightness. Therefore, a photoelectric sensor with excellent water resistance can be formed.
(2) The case 1 can be molded with the space 10 secured between the circuit board 6 and the board cover 19 by the board portion 10 and the board cover 19. Therefore, failure due to thermal stress of circuit elements on the circuit board can be reduced, and the yield in manufacturing can be improved.
(3) Since the substrate cover 19 of the cover member 18 is formed of red PC, the substrate cover 19 can be lit in red by visible light output from the light emitting element 25 on the circuit board 6.
(4) Visible light output from the light emitting element 25 passes through the substrate cover 19 as scattered light due to the space between the circuit board 6 and the substrate cover 19 and the unevenness 23 of the substrate cover 19. Accordingly, since the upper surface and the entire side surface of the substrate cover 19 are lit in red, visibility from the periphery of the photoelectric sensor can be improved.
(5) Since the frame covers 20 and 21 are formed of black PC, reception of visible light by the light receiving element 8 of the light receiving element frame 12 can be substantially blocked. Therefore, it is possible to block the intrusion of visible light into the light receiving element 8 and prevent malfunction due to reception of visible light.
(6) Since the base member 9 is formed around the circuit board 6 to form the board portion 10, the action of mechanical stress on the circuit board 6 is reduced when the terminal member 14 is bent to the back side of the circuit board 6. be able to. Therefore, it is possible to prevent damage to the circuit board 6 and the circuit elements due to mechanical stress, and to improve the manufacturing yield.

In addition, you may change the said embodiment as follows.
The substrate portion 10, the light projecting element frame 11, and the light receiving element frame 12 of the above embodiment may be molded from ABS (acrylonitrile butadiene styrene), PC, or PPS (polyphenylene sulfide) instead of PBT. The cover member 18 may be made of PMMA (polymethyl methacrylate) instead of PC.
The substrate cover 19 may be formed of a PC resin having a color that easily transmits visible light other than red.

  DESCRIPTION OF SYMBOLS 1 ... Case, 6 ... Circuit board, 7 ... Light emitting element, 8 ... Light receiving element, 9 ... Frame member (base member), 11 ... Frame member (light projecting element frame), 12 ... Frame member (light receiving element frame), DESCRIPTION OF SYMBOLS 14 ... Terminal member, 15a-15d ... Terminal, 16a-16d ... Wiring, 17 ... Cover member, 18 ... Cover member, 19 ... Substrate cover, 23 ... Concavity and convexity, 24 ... Space.

Claims (5)

A light emitting element and a light receiving element for detecting an object to be detected;
In a photoelectric sensor in which a circuit board mounted with a control circuit that outputs a detection signal when the detected object is detected based on the operation of the light projecting element and the light receiving element,
Frame members for holding the light projecting element, the light receiving element, and the circuit board, respectively;
A cover member covering the frame member;
A case formed to cover the frame member and the cover member,
A photoelectric sensor, wherein the frame member, the cover member, and the case are molded of a thermoplastic resin. The photoelectric sensor according to claim 1,
A photoelectric sensor comprising a space between a circuit element mounting surface of the circuit board and the cover member. The photoelectric sensor according to claim 1 or 2,
The light projecting element, the light receiving element, and the circuit board are mounted on a metal frame, a frame member that holds the light projecting element, a frame member that holds the light receiving element, and a frame that holds the circuit board A member is formed on a metal frame, the metal frame is bent, and a frame member holding the light projecting element and a frame member holding the light receiving element are suspended on both sides of the frame member holding the circuit board. The photoelectric sensor is characterized in that the cover member is integrally formed so as to cover the frame members. In the photoelectric sensor according to any one of claims 1 to 3,
A photoelectric sensor, wherein a wiring connected to the circuit board is covered with a covering member, and the case is formed so that the wiring covered with the covering member is exposed from the case.   A light projecting element, a light receiving element, a terminal for connecting a circuit board and wiring is formed on a metal frame, a light projecting element frame for holding the light projecting element, a light receiving element frame for holding the light receiving element, A base member for holding the circuit board and a terminal member for holding the terminal are molded on the metal frame with a thermoplastic resin, and the metal frame for electrically connecting the light projecting element and the light receiving element to the circuit board is bent. The light projecting element and the light receiving element are opposed to each other, and a cover member formed of a thermoplastic resin is attached to the light projecting element frame, the light receiving element frame, and the base member, and the light projecting element frame, the light receiving element frame, and the base member are attached. And a method of manufacturing a photoelectric sensor, wherein a case of a thermoplastic resin is molded so as to cover the terminal member.