Electronic device

To provide an electronic device which can be efficiently manufactured with stable quality. A photoelectric sensor 1A includes a cable 20 of which one end is drawn into a casing 10 through a cable insertion opening portion 10c, and a lead frame 25 which is electrically connected to a circuit board 34. A conductive wire 23 of the cable 20 is bonded to the lead frame 25, and an area from the cable insertion opening portion 10c to the bonded portion between the conductive wire 23 and the lead frame 25 is continuously sealed with resin R.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefit of Japanese application serial no. 2017-032290, filed on Feb. 23, 2017. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND

Technical Field

Embodiments of the disclosure relate to an electronic device of which a cable is drawn to the outside.

Related Art

Conventionally, there is a case in which an electronic device of which a covered wire is exposed to the outside is used, for example, in an environment in which a temperature intensively changes over time and a large amount of liquid including oil such as cutting oil or chemicals with high corrosiveness is used. When the electronic device is used under such a relatively harsh environment, there is a case in which a liquid intruding into a gap between outer and inner sheaths of the covered wire or a gap between the inner sheath and a conductive wire intrudes into the electronic device due to a capillary action.

Here, in order to prevent the intrusion of the liquid into the electronic device due to the capillary action, for example, sealing structure of a proximity switch disclosed in Patent Document 1 (Japanese Unexamined Patent Application Publication No. H08-31282 (published on Feb. 2, 1996)) is known. In a proximity switch100disclosed in Patent Document 1, as shown in (a) ofFIG. 7, a cable110is connected to a printed board101at a terminal portion111. As shown in (b) ofFIG. 7, a resin filled chamber102is provided in the proximity switch100and a core wire exposed portion111ain which a part of an insulation coating is peeled off is provided in the terminal portion111of the cable110located at the resin filled chamber102. Then, insulating resin is filled in the resin filled chamber102including the core wire exposed portion111a.

Accordingly, since the insulation resin enters a gap between the core wires of the core wire exposed portion111aand fills the gap, it is possible to prevent intrusion of other moistures or gases into the gap between the core wires of the cable110.

SUMMARY

According to an aspect of the disclosure, there is provided an electronic device including: a casing which is provided with an opening portion; an electronic component which is accommodated in the casing; and a cable of which one end is drawn into the casing through the opening portion and the other end is drawn to the outside of the casing; and a relay connection member that is electrically connected to the electronic component, wherein a core wire of the cable at the one end is bonded to the relay connection member, and an area from the opening portion to the bonded portion between the core wire and the relay connection member is continuously sealed with resin.

DESCRIPTION OF THE EMBODIMENTS

In the proximity switch disclosed in Patent Document 1, it is necessary to peel off a part of the insulation coating. An operation of peeling off a part of the insulation coating is performed by a worker. For that reason, it is difficult to efficiently and uniformly set a length of a portion in which the insulation coating has been peeled off. When the portion in which the insulation coating is peeled off is too long, a problem such as short-circuiting occurs. Meanwhile, when the portion is too short, sealing quality becomes poor.

An embodiment of the disclosure is to provide an electronic device which can be efficiently manufactured with stable quality.

According to the above-described embodiment, since an area from the opening portion to the bonded portion between the core wire and the relay connection member is continuously sealed with the resin, it is possible to prevent a problem in which the liquid intrudes into a portion at the inside of the bonded portion along a gap between the core wire and the insulation coating. In this configuration, the insulation coating of the cable may be peeled off to the end thereof. Therefore, the electronic device can be manufactured efficiently with stable quality.

In the electronic device, the relay connection member may be a member having a fixed shape.

According to the above-described configuration, since the relay connection member is prevented from contacting with other wires inside the casing, short-circuiting can be prevented.

In the electronic device, a sealing section which is partitioned by a partition wall and is adjacent to the opening portion may be provided inside the casing, and the sealing section may be provided with the bonded portion and may be filled with the resin.

According to the above-described configuration, since the sealing section provided with the bonded portion is filled with the resin, it is possible to more reliably prevent intrusion of the liquid into the casing.

In the electronic device, the cable may include a plurality of core wires, a plurality of the relay connection members may be provided to correspond to the plurality of core wires, and the electronic device may further include a holding member that has a plurality of holes through which the plurality of relay connection members pass and holds the plurality of relay connection members to be separated from each other.

According to the above-described configuration, since the plurality of relay connection members are held by the holding member to be separated from each other, short-circuiting inside the casing can be prevented.

In the electronic device, the cable may include a plurality of the core wires, a plurality of the relay connection members may be provided to correspond to the plurality of core wires, the electronic device may further include a holding member that has a plurality of holes through which the plurality of relay connection members pass and holds the plurality of relay connection members to be separated from each other, and the holding member may partition the sealing section inside the casing.

According to the above-described configuration, one end of the relay connection member can be easily disposed at the sealing section. Further, since the sealing section is divided by the holding member, it is possible to prevent the resin from leaking to the outside of the sealing section.

In the electronic device, the casing may be formed of metal.

When the core wire is wired to the electronic component inside the metallic casing, the possibility of short-circuiting increases. Meanwhile, according to the above-described configuration, the cable is electrically connected to the electronic component through the relay connection member inside the casing. For that reason, short-circuiting can be prevented.

The electronic device may be a photoelectric sensor or a proximity sensor.

The electronic device according to an aspect of the disclosure can be efficiently manufactured with stable quality.

First Embodiment

An embodiment of the disclosure will be described below with reference toFIGS. 1 to 5.

A configuration of a photoelectric sensor which is a sensor of the embodiment will be described below. Further, in the embodiment, the photoelectric sensor will be exemplified as an electronic device of which a covered wire (a cable) is drawn to the outside. However, the electronic device is not essentially limited to the photoelectric sensor. For example, various sensors such as a proximity sensor, a displacement sensor, a pressure sensor, an ultrasonic sensor, and a vibration sensor and other electronic devices which are not used for a sensing purpose can be employed. That is, the configuration of the embodiment can be applied to the electronic device of which the covered wire is drawn to the outside.

Here, the photoelectric sensor to be described in the embodiment is a sensor which detects the existence of an object or a change in surface state by using various properties of light. The photoelectric sensor includes a light projecting unit which emits light and a light receiving unit which receives light. When the transmitted light is interrupted or reflected by a detection object, the amount of light reaching the light receiving unit changes. The light receiving unit detects this change, converts the change into an electric signal, and outputs the electric signal to the outside. As the light to be used, visible light and infrared light are mainly used, but the disclosure is not limited thereto. Examples of the photoelectric sensor include, for example, a transmission type sensor, a reflection type sensor, and a regressive reflection type sensor. In the embodiment, for example, the reflection type photoelectric sensor will be described. However, a covered wire connection structure of the embodiment is not limited to the type of the photoelectric sensor.

FIG. 2in which (a) is an exploded perspective view showing an overall configuration of a photoelectric sensor1A when viewed from an obliquely rear side which is near a cable20.FIG. 2in which (b) is an exploded perspective view showing an overall configuration of the photoelectric sensor1A when viewed from an obliquely front side.

As shown inFIGS. 2(a) and 2(b), the photoelectric sensor1A of the embodiment includes a casing10which includes a main casing10aand a main cover10b, a cable20which is drawn out from the casing10to be exposed to the outside, a sensing module30and a display unit40which are provided inside the casing10, an insulation wall17which insulates the sensing module30from the casing10, and a plurality of lead frames25(relay connection members) which electrically connect the cable20and the sensing module30(the electronic component) to each other.

The cable20includes a sheath21which is an outer sheath, a plurality of covering portions22which are inner sheaths, and a plurality of conductive wires23(core wires) which are respectively covered by the plurality of covering portions22. The conductive wire23of the cable20is bonded to the corresponding lead frame25by soldering.

The casing10has, for example, a substantially rectangular parallelepiped shape having a component accommodation space portion11and a resin filling space portion12. The casing10is provided with a partition wall19. The component accommodation space11and the resin filling space portion12are partitioned by the partition wall19and the holding member13.

A top surface display cover14is provided at a top surface of the main casing10aof the casing10and the top surface display cover14is provided with a top surface light projecting member14aprovided at an opening. The top surface display cover14is formed as, for example, a metallic member and may be formed as a stainless steel member. The top surface display cover14is manufactured by pressing, for example, a metal plate.

An O-ring15ais interposed between the top surface display cover14and the main casing10a. Accordingly, the component accommodation space11inside the main casing10ais sealed from an external space. In addition, the top surface display cover14is fixed to the main casing10aby, for example, laser welding.

Further, a front surface of the main casing10ais provided with a front surface cover16having a front surface light projecting plate16ain an opening.

The front surface cover16is forming as, for example, a metallic member and may be formed as a stainless steel member. The front surface cover16is manufactured by pressing, for example, a metal plate.

An O-ring15bis interposed between the front surface cover16and the main casing10a. Accordingly, the component accommodation space11inside the main casing10ais sealed from an external space. In addition, the front surface cover16is fixed to the main casing10aby, for example, laser welding.

The cable20is inserted into the casing10at the rear side of the main casing10a. Additionally, in the embodiment, a light emitting side of a light projecting unit31and a light receiving side at a light receiving unit32to be described later will be described as a front side of the casing10.

The main cover10bis fixed to the main casing10aby, for example, laser welding over the entire periphery of the peripheral edge.

Both the main casing10aand the main cover10bare formed as, for example, metallic member of stainless steel or the like. The main casing10ais manufactured by, for example, metal injection molding (MIM) and the main cover10bis manufactured by pressing, for example, a metal plate.

A cable insertion opening portion10c(an opening portion) having a circular cross-section is provided at the lower surface of the rear side of the main casing10aand one end of the cable20is inserted into the cable insertion opening portion10c. The cable insertion opening portion10cis sealed by a cylindrical bush26and a fixed member27.

The bush26is formed as, for example, a rubber member and may be formed of any one of nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), and fluorine-based rubber. In addition, the bush does not need to be formed of rubber and various materials such as plastic can be used as long as a gap between the cable20and the casing10can be sealed.

The fixed member27has an annular shape and is formed as, for example, a metallic member of true weave or the like. The fixed member27includes the bush26and is fitted into the cable insertion opening portion10cof the main casing10a. The fixed member27fixes the bush26and the cable20. Accordingly, the sealing property of the component accommodation space11of the casing10is kept.

FIG. 3is a cross-sectional view showing an overall configuration of the photoelectric sensor1A. As shown inFIG. 3, in the component accommodation space11inside the main casing10aof the photoelectric sensor1A, the sensing module30is accommodated at the center and the display unit40is provided at the upper portion. The sensing module30includes the light projecting unit31, the light receiving unit32, and a circuit board34(an electronic component).

The light projecting unit31includes a light emitting element31awhich is a light source, a light projecting and receiving integrated lens33, the front surface light projecting plate16a, and a light projecting circuit formed on the circuit board34.

The light receiving unit32includes a light receiving element32a, the light projecting and receiving integrated lens33, the front surface light projecting plate16a, and a light receiving circuit formed on the circuit board34.

A transparent member42and a light guiding member43are provided above the display LED41and light turned on by the display LED41is emitted to the outside through the transparent member42, the light guiding member43, and the top surface light projecting member14aof the top surface display cover14. In addition, the top surface light projecting member14ais formed as a member that diffuses light so that the light emitted from the display LED41is visible from the outside.

FIG. 4is a block diagram showing a configuration of a control system of the photoelectric sensor1A. As shown inFIG. 4, the circuit board34which is a component of a control system of the photoelectric sensor1A of the embodiment includes a power source34a, a control unit34b, and an output unit34c. The power source34asupplies electric power supplied by the cable20to the control unit34b, the output unit34c, the light projecting unit31, the light receiving unit32, and the display unit40.

The control unit34bincludes a CPU and other circuits. The control unit34bdetects a sensor signal input to the light receiving unit32and displays a detection result on the display unit40by controlling the light projecting unit31and the light receiving unit32and transmits a signal indicating the detection result to the outside through the cable20by controlling the output unit34c.

In the above-described photoelectric sensor1A, for example, a laser beam is emitted by the light emitting element31aof the light projecting unit31. The laser beam is emitted to the outside through the light projecting and receiving integrated lens33and the front surface light projecting plate16a, is reflected by a detection object (not shown), and is returned to the sensing module30. In the sensing module30, this reflected light is received by the light receiving element32athrough the front surface light projecting plate16aand the light projecting and receiving integrated lens33. In the circuit board34, an electric signal having strength corresponding to the light receiving amount of the reflected light is generated. Accordingly, the photoelectric sensor1A detects the existence of an object based on the electric signal or outputs a signal indicating the light receiving amount of the photoelectric sensor1A. The output is performed by the display unit40and is transmitted to the outside by the output unit34c.

(Cable Connection Portion Structure of Photoelectric Sensor)

A connection portion structure of the cable20of the photoelectric sensor1A in the above-described configuration will be described below.

For example, the photoelectric sensor is sometimes used in an environment in which a large amount of liquid including oil such as cutting oil or chemicals with high corrosiveness is used. In this case, there is a case in which a liquid intrudes into a gap between the sheath corresponding to the outer sheath and the covering portion corresponding to the inner sheath or a gap between the conductive wires corresponding to the core wires of the covering portion in accordance with deterioration of the covering portion and the sheath of the cable. In some cases, the liquid intruding into the cable intrudes into the casing along the cable due to a capillary action.

Here, in order to prevent the intrusion of the liquid into the electronic device due to the capillary action, for example, a method of providing a core wire exposed portion obtained by peeling off a part of an insulation coating and sealing the portion with insulation resin is employed in the related art. Accordingly, a sealing property is ensured for the liquid intruding along the inner sheath and the conductive wire.

However, in this method, since there are many processes depending on manual work at the time of peeling off a part of the insulation coating, a problem arises in that a variation in sealing quality is large and the photoelectric sensor fails within a short time. Specifically, there is a possibility of short-circuiting when the insulation coating is largely peeled off and the intrusion of the liquid cannot be sufficiently prevented when the insulation coating is peeled off just a little.

Here, the photoelectric sensor1A of the embodiment has a connection portion structure of the cable20as follows.

FIG. 1in which (a) is a perspective view showing a connection portion structure of the cable20of the photoelectric sensor1A of the embodiment.FIG. 1in which (b) is a cross-sectional view of a main part showing a connection portion structure of the cable20of the photoelectric sensor1A.

As shown inFIG. 1, in the photoelectric sensor1A of the embodiment, the cable20passes though the cable insertion opening portion10cand the bush26. One end of the cable20is drawn into the casing10and is disposed inside the resin filling space portion12(the sealing section). The other end of the cable20is drawn to the outside of the casing10. In the casing10, the plurality of covering portions22and the sheath21of one end of the cable20are peeled off.

The holding member13is an insulation member and includes a plurality of through-holes13a(holes) corresponding to the plurality of lead frames25. The holding member13is disposed to contact the partition wall19and covers the resin filling space portion12. The holding member13holds the plurality of lead frames25to be separated from each other.

The lead frame25is a conductive member of which a shape is fixed. The lead frame25does not have flexibility (has rigidity). One end of the lead frame25is electrically connected to an external connection terminal (not shown) of the circuit board34by soldering or laser welding. The other end of the lead frame25is bent and is disposed inside the resin filling space portion12through the through-hole13aprovided in the holding member13. The other end of the lead frame25is bonded to the conductive wire23in the resin filling space portion12by soldering or laser welding.

The resin filling space portion12is filled with the resin R. The resin R continuously covers an area from the cable insertion opening portion10cto at least the bonded portion between the conductive wire23and the lead frame25to seal the area. Here, the resin R covers the bonded portion between the lead frame25and the conductive wire23exposed from the covering portion22inside the resin filling space portion12. Further, the resin R seals a gap among the cable insertion opening portion10c, the bush26, and the cable20. The resin R seals a gap between the lead frame25and the through-hole13aof the holding member13and a gap among the holding member13, the casing10, and the partition wall19. As the resin R, for example, insulation resin such as epoxy resin can be used.

The conductive wire23is bonded to the lead frame25and the bonded portion is sealed with the resin R. The bonded portion is not covered at the covering portion22and the resin R directly contacts the conductive wire23and the lead frame25. The resin R continuously seals an area from the cable insertion opening portion10cto the bonded portion. Accordingly, even when a liquid rises to the inside of the casing10along a gap between the covering portion22and the conductive wire23by the capillary action, the liquid cannot intrude into a portion at the inside of the bonded portion between the conductive wire23and the lead frame25. Therefore, it is possible to prevent the intrusion of the liquid into the component accommodation space11.

Further, the plurality of lead frames25are held by the holding member13to be separated from each other. Each of the plurality of lead frames25is a member that has a fixed shape and has no flexibility. For that reason, it is possible to prevent a contact with other wires in the component accommodation space11or a contact between the lead frames25. Therefore, it is possible to electrically connect the conductive wire23and the circuit board34to each other by disposing the plurality of lead frames25in a narrow space. The lead frame25may not be covered by an insulation body.

A method of assembling the photoelectric sensor1A having a connection portion of the cable20will be described below.

FIG. 5is a perspective view showing a method of assembling the photoelectric sensor1A. As shown inFIG. 5, the sheath21and the covering portion22of the distal end at the connection side to the circuit board34in the cable20are peeled off in order to assemble the photoelectric sensor1A of the embodiment.

The cable20passes through the cable insertion opening portion10cand the bush26. One end of the cable20is drawn into the casing10and is disposed inside the resin filling space portion12(the sealing section). The other end of the cable20is drawn to the outside of the casing10. Inside the casing10, the sheath21and the plurality of covering portions22of one end of the cable20are peeled off and the plurality of conductive wires23are exposed. The fixed member27is press-inserted into the cable insertion opening portion10c. Accordingly, the sealing property of the cable insertion opening portion10cis improved.

Meanwhile, as shown inFIG. 5, one end of the lead frame25is connected to the circuit board34of the sensing module30by soldering or laser welding. Next, the sensing module30having the lead frame25soldered thereto is covered by the insulation wall17. In the embodiment, the insulation wall17is a casing which covers the outside of the sensing module30having the lead frame25soldered thereto. The other end of the lead frame25is exposed from the insulation wall17. The insulation wall17insulates the lead frame25from the metallic casing10and the partition wall19. The other end of the lead frame25of which one end is bonded to the circuit board34of the sensing module30is inserted through the through-hole13aof the holding member13. Then, the sensing module30having the insulation wall17attached thereto is accommodated into the component accommodation space11of the main casing10ahaving the cable20attached thereto from the lateral side. The holding member13and the partition wall19partition the resin filling space portion12. The resin filling space portion12is adjacent to the cable insertion opening portion10c. The other end of the lead frame25is disposed inside the resin filling space portion12.

In the resin filling space portion12, the lead frames25facing the corresponding conductive wires23are connected thereto by soldering, laser welding, or the like.

Finally, the main casing10ais laid sideways and the resin filling space portion12is filled with the resin R such as an epoxy resin. When the main cover10bis attached to the main casing10aafter the resin R is cured, the photoelectric sensor1A is completed.

Second Embodiment

Another embodiment the disclosure will be described below with reference toFIG. 6. Additionally, configurations other than those described in the embodiment are the same as those in the first embodiment. Further, for convenience of description, members having the same functions as the members shown in the drawings of the first embodiment are denoted by the same reference numerals and the description thereof is omitted.

In the photoelectric sensor1A of the first embodiment, the conductive wire23of the cable20is directly connected to the lead frame25. In contrast, a photoelectric sensor1B of the embodiment has a different configuration in which the conductive wire23is electrically connected to the lead frame25through a mold interconnect device (MID)18.

FIG. 6in which (a) is a perspective view showing a configuration of the casing10and the lead frame25of the photoelectric sensor1B of the embodiment. Here, the sensing module30is not shown in the drawings.FIG. 6in which (b) is a perspective view showing a connection portion structure between the lead frame25and the cable20when viewed from the rear side.FIG. 6in which (c) is a perspective view showing a structure including the lead frame25and the mold interconnect device18when viewed from the front side.

The mold interconnect device18(the relay connection member or the holding member) is formed such that an electric circuit, an electrode, or a wiring pattern is formed on a resin injection-molded product. In the embodiment, the mold interconnect device18, for example, has a configuration in which a resin portion18a(a holding member) having a substantially L-shaped cross-section and a plurality of metallic patterns18b(relay connection members) are integrally formed by injection-molding. The mold interconnect device18includes a plurality of through-holes18cwhich correspond to the plurality of conductive wires23and a plurality of through-holes18dwhich correspond to the plurality of lead frames25. The plurality of metallic patterns18bare respectively formed to electrically connect the corresponding through-holes18dto the through-holes18c. The plurality of lead frames25are respectively connected to the metallic patterns18bof the mold interconnect device18by soldering or the like while passing through the through-holes18d. The plurality of conductive wires23are respectively inserted through the through-holes18cand are connected to the metallic patterns18bof the mold interconnect device18by soldering or the like. In this way, the plurality of conductive wires23are electrically connected to the circuit board34through the mold interconnect device18and the lead frame25.

A part of the mold interconnect device18partitions the resin filling space portion12along with the partition wall19. The resin filling space portion12is filled with the resin R. The bonded portion (the position of the through-hole18c) between the conductive wire23and the mold interconnect device18and the bonded portion (the position of the through-hole18d) between the mold interconnect device18and the lead frame25are sealed with the resin R. When the main cover10bis attached to the main casing10aafter the resin R of the resin filling space portion12is cured, the photoelectric sensor1B is completed.

In the photoelectric sensor1B of the embodiment, the plurality of metallic patterns of the mold interconnect device18are held by the resin portion18ato be separated from each other. For that reason, short-circuiting can be prevented even when the plurality of conductive wires23and the circuit board34are electrically connected in a narrow space. Further, the assembly can be easily performed.

Modified Example

Further, in the second embodiment, the lead frame25is connected to the mold interconnect device18. However, an aspect of the disclosure is not essentially limited thereto. For example, it is possible to substitute the lead frame with the mold interconnect device. In this case, the mold interconnect device having the metallic pattern is bonded to the circuit board. Accordingly, when the conductive wire is soldered to the metallic pattern of the mold interconnect device, it is possible to prevent the liquid from intruding into a portion at the inside of the metallic pattern.

Further, a fixed component or a harness of which a shape is fixed by resin or the like may be used instead of the plurality of lead frames25. Since the shape of the harness is fixed and the wires are covered, short-circuiting inside the casing10can be prevented. The plurality of conductive wires23are connected to the harness.

Further, the disclosure is not limited to the above-described embodiments, various modifications can be made within the scope of claims, and embodiments obtained by an appropriate combination of technical means respectively disclosed in other embodiments are also included in the technical scope of the disclosure.