JP3579975B2 - Penetration type proximity sensor - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a penetration type proximity sensor, and more particularly to a penetration type proximity sensor for detecting a metal body passing through a penetration portion.
[0002]
[Prior art]
Generally, a high-frequency oscillation type proximity sensor is used as a sensor for magnetically detecting the presence of a metal body in a non-contact manner. Among such proximity sensors, a penetration type proximity sensor that outputs an electric signal each time a metal body such as a pachinko ball passes through a cylindrical coil is known.
[0003]
FIG. 12 is a block diagram showing a circuit configuration of such a proximity sensor. An oscillation circuit 101 is connected to both ends of the coil 16. The oscillating circuit 101 constitutes an LC oscillating circuit by the coil 16 and the internal capacitance. The oscillating circuit 101 oscillates at a constant frequency, and its output is transmitted to the detection circuit 102. When a metal body approaches the coil 16, the conductance of the coil 16 increases, the oscillation condition of the oscillation circuit 101 changes, the amplitude decreases, or the oscillation level falls below a predetermined threshold. The proximity sensor detects the approach or passage of the metal object by the decrease in the amplitude or the oscillation level, and outputs an object detection signal via the output circuit 103. The detection circuit 102 and the output circuit 103 constitute a signal processing unit that detects the proximity of a metal body based on a change in the oscillation state.
[0004]
In such a penetrating type proximity sensor, when an oscillation circuit formed on a wiring board is connected to a coil, it is necessary to solder an end of the coil winding to an electrode pad formed on the wiring board. Therefore, conventionally, (1) a method of soldering the end of the coil winding to the electrode pad of the wiring board and fixing the periphery of the soldered portion with a silicone resin or an adhesive to strengthen the wire is used. Or (2) When the coil winding is thin, a method of connecting to an electrode pad of a wiring board by using a relay terminal at an end of the coil winding is used.
[0005]
[Problems to be solved by the invention]
However, in the method of connecting the coil and the circuit portion (oscillation circuit) in this manner, an electrode pad is provided on the surface of the wiring board, and the end of the coil winding is connected to the electrode pad. For example, when a circuit wiring having the same potential as the electrode pad (for example, a metal foil for shielding) is formed on the back surface of the wiring board, a through hole is formed in the wiring board to form a circuit wiring on the back surface. And the electrode pad on the surface had to be electrically connected. For this reason, the cost of the wiring board has increased, and the cost of the proximity sensor has also increased (the cost of a wiring board having through holes is 1.5 to 2 times as much as that of a wiring board without through holes).
[0006]
The present invention has been made in view of the above-described drawbacks of the conventional example, and an object of the present invention is to provide a structure that can easily and inexpensively connect electrode pads formed on both front and back surfaces of a wiring board. To provide.
[0007]
DISCLOSURE OF THE INVENTION
The penetration type proximity sensor according to claim 1, a coil spool having a through hole through which an object to be detected passes, a wiring board on which a sensor circuit including an oscillation circuit is mounted, and a coil wound around the coil spool, and both ends thereof are wound. In a penetration type proximity sensor having a coil winding connected to an oscillation circuit of the wiring board, a shield portion is formed on a surface of the wiring board opposite to the sensor circuit, and a coil winding is formed on both sides of the wiring board. A projecting portion for winding a wire is provided; an electrode pad connected to the shield portion and an electrode pad to be connected to the electrode pad are provided on the back surface of one projecting portion; and the sensor circuit is provided on the surface of the other projecting portion. Providing an electrode pad connected to the coil spool, providing a board connection portion on the coil spool, and providing an insertion portion on the wiring board, and inserting the insertion portion into the board connection portion. Accordingly, the wiring board is held by the coil spool so as to be perpendicular to the axis of the through hole, and both ends of the coil winding wound on the coil spool are wound around the respective projecting portions and soldered. Thereby, the electrode pads formed on the front and back surfaces of the one protruding portion are electrically connected to each other .
[0008]
When a coil winding is wound around the protruding portion and soldered, the electrode pads provided on the front and back surfaces of the protruding portion are made conductive by the coil winding or the solder.
[0009]
Therefore, the front side electrode pad and the back side electrode pad can be connected without making a through hole or the like in the wiring board, and the electrical connection on the front and back of the wiring board can be realized with a simple structure at a low cost. it can. Further, since the ends of the coil winding can be soldered to the front and back electrode pads, the coil winding can be fixed securely and firmly.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
A penetration type proximity sensor A for detecting penetration of a pachinko ball or the like according to an embodiment of the present invention will be described with reference to the drawings. 1 is an exploded perspective view of the proximity sensor A, FIG. 2 is an exploded perspective view of the upside down state of FIG. 1, and FIG. 3 is an exploded side view partially broken. As shown in these figures, the proximity sensor A is configured such that a coil portion and a circuit portion are housed in a flat rectangular parallelepiped housing including an upper case 1 and a lower case 2.
[0011]
Substantially circular through holes 3 and 4 are formed in the upper and lower cases 1 and 2 constituting the housing so as to face each other. Elastic pieces 6 and 7 having engaging claws 5 are respectively suspended from the corner portion and both side surfaces of the upper case 1, and the lower case 2 is opposed to the engaging claws 5 by protrusions 8 (of the corner portion). The projections are not shown), and the upper and lower cases 1 and 2 are integrated by putting the upper case 1 on the lower case 2 and engaging the engagement claws 5 with the projections 8. Is configured. A ring-shaped protruding edge 9 is provided around the through hole 4 of the lower case 2 toward the inner surface of the lower case 2, and a part of the protruding edge 9 is used to position a shield ring 46. Projection 10 is provided. A pin 11 is erected near the through hole 4 on the inner surface of the lower case 2. Further, a concave portion 12 for holding a protruding portion 40 of a wiring board 29 described later is formed on the left and right side walls near the pin 11 of the lower case 2. The upper case 1 also has a through hole 3 facing the through hole 4 of the lower case 2, and a ring-shaped protruding edge 13 is provided around the through hole 3. A projection 14 for positioning the shield ring 45 is provided at a part of the projection 13.
[0012]
A coil portion and a circuit portion as shown in FIG. 5 are accommodated between the upper and lower cases 1 and 2. The coil portion is obtained by winding a coil 16 around a coil spool 15 having a shape as shown in FIGS. 6 to 8, and a circuit portion is connected to a board connecting portion 17 provided on the coil spool 15. The coil spool 15 has a through hole 20 for passing a metal body (that is, a pachinko ball) inside a winding drum 19 for winding the coil winding 18. The board connecting portion 17 protrudes from the end. Between the flanges 21 and 22 provided at the upper and lower ends of the winding body 19, a portion (hereinafter referred to as an auxiliary winding) 24 around which only the twisted portion 23 of the coil winding 18 is wound, and a single wire portion 25 of the coil winding 18. (Hereinafter referred to as a main winding portion) 26 and is divided by a partition portion 27. An inclined guide surface 28 is formed on the lower flange 22 to smoothly guide the twisted portion 23 wound around the auxiliary winding portion 24 to the surface of the board connecting portion 17.
[0013]
On the lower surface of the board connecting portion 17, a holding piece 30 for holding the end of the wiring board 29 in the circuit portion and a projection 31 having a low height are provided. A groove 32 having a height equal to the thickness of the wiring board 29 is formed therebetween, and the height of the protrusion 31 is smaller than the thickness of the wiring board 29. Further, a pair of relay pins 33 for looping the twist portion 23 is integrally formed on the upper surface of the board connecting portion 17.
[0014]
As shown in FIGS. 1 and 2, the circuit portion is configured by mounting components such as an IC, a resistor, and a capacitor on a wiring board 29 to form an oscillation circuit, a detection circuit, an output circuit, and the like. . An insertion portion 35 for insertion into the substrate connection portion 17 is provided at the tip of the wiring board 29, and a small hole 36 is opened in the insertion portion 35. When the insertion portion 35 is inserted into the groove 32 between the board connection portion 17 and the holding piece 30, the protrusion 31 provided on the board connection portion 17 fits into the small hole 36 of the insertion portion 35 and the wiring The board 29 is prevented from coming off, and the board connecting portion 17 and the wiring board 29 are positioned with respect to each other. Pin insertion holes 37 and 38 are formed in the wiring board 29 and the board connecting portion 17 at positions corresponding to the pins 11 of the lower case 2. Further, on both sides of the insertion portion 35, there are provided protrusions 40 protruding laterally. As shown in FIG. 9, on the front side of the wiring board 29, a circuit pattern (a copper foil portion is shown by matte) 51 for mounting components such as an IC, a resistor, and a capacitor constituting an oscillation circuit and a detection circuit. The one protruding portion 40 is provided with an electrode pad 41 on the ground side of the oscillation circuit, and the other protruding portion 40 is provided with an electrode pad 43 on the signal output side. As shown in FIG. 10, a copper foil 39 for electrostatic shielding is adhered to almost the entire back surface of the wiring board 29, and an electrode pad electrically connected to the copper foil 39 for shielding is provided on one protruding portion 40. The dummy electrode 44 is provided on the other protrusion 40.
[0015]
Thus, in the step of winding the coil winding 18 around the coil spool 15 to which the wiring board 29 is connected, first, the twist portion 23 at one end of the coil winding 18 is wound around one projecting portion 40 of the wiring board 29. Next, as shown in FIG. 1 or FIG. 5, after the twist portion 23 is wound around the relay pin 33, the twist portion 23 at the beginning of winding is wound around the auxiliary winding portion 24 for approximately one turn, and the single wire portion 25 is further wound. The coil 16 is wound around the winding drum 19 by winding several tens of turns around the main winding part 26. When the single-wire portion 25 is wound around the main winding portion 26 in this manner, the twisted portion 23 at the end of winding is wound around the auxiliary winding portion 24 (or from the top of the single-wire portion 25 to the main winding portion 26) for approximately one turn, and relayed. After being wrapped around the pin 33, it is wound around the other protrusion 40. After that, the twisted portions 23 wound around the projecting portions 40, 40 are dipped in a solder bath and soldered to the respective electrode pads 41, 42, 43 and the dummy electrodes 44 of the projecting portions 40, 40 by dip soldering. In this manner, for example, as shown in FIG. 11A, the twisted portion 23 of the coil winding 18 is wound around both projecting portions 40, 40, and as shown in FIG. When the dip soldering is performed, one twist portion 23 is soldered and fixed to the electrode pads 41 and 42. Moreover, the front and back electrode pads 41 and 42 are also electrically connected by the solder 52, so that it is not necessary to connect the front and back electrode pads 41 and 42 by through holes or the like. Further, the twist portion 23 is also soldered to the front and back electrode pads 41 and 42, so that the fixing strength is improved. Further, since the other twisted portion 23 is also soldered to the electrode pad 43 and the dummy electrode 44, the fixing strength of the twisted portion 23 is improved. As a result, the coil 16 is securely connected to the circuit portion, and the front and back of the wiring board 29 are simultaneously connected. The proximity sensor A for detecting a pachinko ball is in an environment where it is constantly exposed to the impact of the pachinko ball. In this proximity sensor A, the coil winding 18 is fixed on both surfaces of the projecting portion 40. As a result, it became strong and was effective as a measure against coil disconnection.
[0016]
By winding the coil winding 18 around the coil spool 15 in this way, as shown in FIG. 5, the twist portion (particularly, the twist portion at the beginning of winding) 23 of the coil winding 18 is separated from the single wire portion 25 to form a winding drum. The single wire portion 25 can be wound around the portion 19, and the single wire portion 25 can be prevented from becoming thick and the single wire portion 25 can be wound almost orderly and stably. Accordingly, the space for winding the coil winding 18 is reduced due to the thickening, and there is no possibility that the coil winding 18 cannot be sufficiently wound. In addition, it is possible to prevent the insulating film of the single wire portion 25 from peeling off by rubbing against the twist portion 23 and to prevent an interlayer short circuit from occurring in the single wire portion 25. Furthermore, since the single wire portion 25 can be stably wound around the winding drum portion 19, the coil characteristics are improved and the detection sensitivity is stabilized.
[0017]
The coil spool 15 around which the coil 16 is wound is sandwiched from above and below by shield rings 45 and 46 for magnetic shielding. The shield rings 45 and 46 are metal ring-shaped members formed of, for example, a copper foil plate. By combining these members to cover the outer peripheral portion of the coil 16, it is possible to prevent the magnetic flux of the coil 16 from leaking to the outer peripheral portion. This prevents a malfunction due to surrounding metal. The shield rings 45 and 46 are provided with thin notches 47 and 48 at the front edge and the rear edge, respectively, so as not to touch the coil winding 18 and the like. 49 are protruded. Further, a notch concave portion 50 is provided in the inner peripheral portion on the rear side. Thus, when the shield rings 45 and 46 are put on the upper and lower sides of the coil spool 15, the projecting pieces 49 projecting from the lower shield ring 46 fit into the small holes 36 of the wiring board 29, and the shield ring 46 rotates. While being stopped, the lower shield ring 46 touches the copper foil 39 and is grounded. When the shield rings 45 and 46 are housed in the housing together with the coil spool 15 and the like, the upper shield ring 45 contacts the lower shield ring 46 so that the upper shield ring 45 is also grounded. In addition, the projecting piece 49 of the upper shield ring 45 is used to reduce the number of parts by making the upper and lower shield rings 45 and 46 have the same shape, so that this may be omitted. Alternatively, the protruding piece 49 of the upper shield ring 45 may be fitted into the small hole 36 or the like formed in the board connecting portion 17.
[0018]
Now, in assembling the proximity sensor A, when the lower shield ring 46 is placed around the protruding edge 9 of the lower case 2, the notch recess 50 of the shield ring 46 fits into the projection 10 of the lower case 2 and rotates. Be stopped. Then, when the coil portion and the circuit portion are housed in the lower case 2 by pressing the pins 11 of the lower case 2 into the respective pin insertion holes 37 and 38 of the wiring board 29 and the board connecting portion 17, the wiring board 29 protrudes. The portion 40 is housed in the concave portion 12 of the lower case 2 and positioned and held, and the protruding piece 49 of the lower shield ring 46 is inserted into the small hole 36 of the wiring board 29. After the upper shield ring 45 is put on the coil spool 15 and the upper case 1 is put on from above, the notch recess 50 of the upper shield ring 45 fits into the projection 14 of the upper case 1 and 45 is stopped. When the upper case 1 is pressed against the lower case 2, the engaging claws 5 provided on the elastic pieces 6, 7 of the upper case 1 engage with the projections 8 of the lower case 2, and the upper and lower cases 1, 2 are integrated. The coil portion and the circuit portion are housed in the housing as shown in FIG. In the proximity sensor A assembled in this manner, the through-holes 3, 20, and 4 of the upper case 1, the coil spool 15, and the lower case 2 continuously form a through portion through which a metal body passes.
[0019]
The distance L between the coil 16 and the shield rings 45 and 46 shown in FIG. 4 affects the detection sensitivity of the proximity sensor A. In this proximity sensor A, it is possible to prevent the distance L from being reduced due to the thickening of the coil 16. Therefore, the detection sensitivity of the proximity sensor A can be stabilized. The shield rings 45 and 46 also serve as an electrostatic shield and need to be electrically insulated. However, since the coil winding 18 is wound almost in an orderly manner, the shield rings 45 and 46 are thickened. There is no danger of contact with the coil winding 18, and an electrostatic problem can be solved.
[0020]
Note that the vertical direction used in the above description is a matter of convenience irrespective of the vertical direction in the use state of the proximity switch, and in the actual use state, the vertical direction is set so that the copper foil for shielding is on the upper surface side. It may be used in an inverted state.
[Brief description of the drawings]
FIG. 1 is an exploded perspective view of a penetration type proximity sensor according to an embodiment of the present invention.
FIG. 2 is an exploded perspective view of the proximity sensor in an upside-down state.
FIG. 3 is a partially cutaway side view of the proximity sensor according to the first embodiment;
FIG. 4 is a sectional view showing an assembled state of the proximity sensor according to the first embodiment;
FIG. 5 is a side view showing a coil part and a circuit part assembled together.
FIG. 6 is a plan view of the same coil spool.
FIG. 7 is a bottom view of the same coil spool.
FIG. 8 is a side view of the same coil spool.
FIG. 9 is a front view of the wiring board.
FIG. 10 is a rear view of the wiring board.
FIGS. 11A and 11B are a side view and a plan view showing a coil winding wound around a protruding portion of a wiring board; FIGS.
FIG. 12 is a block diagram for explaining the principle of a penetration type proximity sensor.
[Explanation of symbols]
15 Coil spool 16 Coil 18 Coil winding 23 Twist part of coil winding 29 Wiring board 39 Copper foil 40 for shielding Projection 41 Electrode pad 42 Electrode pad 43 Electrode pad 44 Dummy electrode 51 Electrode pattern 52 Solder

Claims (1)

A coil spool having a through hole through which a detection target passes;
A wiring board on which a sensor circuit including an oscillation circuit is mounted,
A coil winding wound around the coil spool, both ends of which are connected to an oscillation circuit of the wiring board;
In a penetration type proximity sensor having
A shield portion is formed on the surface of the wiring board opposite to the sensor circuit, and furthermore, a protrusion for winding a coil winding is provided on both sides of the wiring substrate, and the shield portion is provided on the back surface of one of the protrusions. Providing a connection electrode pad and an electrode pad to be connected to the electrode pad, providing an electrode pad connected to the sensor circuit on the surface of the other protrusion,
By providing a board connection portion on the coil spool and providing an insertion portion on the wiring board, and inserting the insertion portion into the board connection portion so that the wiring board is perpendicular to the axis of the through hole. Held on the coil spool,
By winding both ends of the coil winding wound on the coil spool around each of the protrusions and soldering, the electrode pads formed on the front and back surfaces of one of the protrusions are electrically connected to each other. A penetration type proximity sensor characterized by the above-mentioned.

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