JPH08321237A - Proximity switch - Google Patents

Abstract

PURPOSE: To provide a proximity switch in which can be performed the specified sensing operations certainly even through a metal object to be sensed is charged electrostatically and in which can be easily achieved of a thin construction as a whole. CONSTITUTION: In a case 1 a shield plate 11 is accommodated in a position upstream of a hollow core coil 3 in the direction in which a metal object to be sensed M passes, and a cover 5 enclosing one end 1a in the longitudinal direction of the case 1 is detained fast to the case 1 in such a condition as flush with the opening end face at the case other end in the longitudinal direction. The coil 3 is wound on a cylinder 7 formed fast on the inside surface of the cover 5 so that the configuration omits any spool fitted with flanges at the two ends.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an object to be detected made of metal,
For example, the present invention relates to a proximity switch used when detecting passage of a pachinko ball of a game machine.

[0002]

2. Description of the Related Art Conventionally, as a switch of this kind, an object to be detected, for example, a pachinko ball, is passed through an air-core coil, and when the pachinko ball is passed, the oscillation in a detection circuit is stopped, whereby the pachinko ball is moved. Proximity switches that detect the passage of balls are known. As shown in FIG. 7, such a conventional proximity switch has a tubular coil spool 103 having flange portions 103a and 103b at both axial ends in a box-shaped case 102 having a passage hole 101 for pachinko balls M. The wound air core coil 104 is concentrically housed in the passage hole 101, a printed wiring board (not shown) for the circuit configuration is housed therein, and the passage hole 105 corresponding to the passage hole 101 is housed. The cover 106 having the above is brought into contact with the opening end surface of the case 102, and the engaging projection 107 on the cover 106 side is engaged and fixed to the engaging hole portion 108 formed on the opening end side of the case 102. Has been done.

[0003]

In the conventional proximity switch having the above-mentioned structure, the air core coil 104 has the coil spool 103 having the rib portions 103a and 103b at both ends.
Since the case 102 is wound around and housed in the case 102, the thickness of the case 102 is restricted by the thickness of the flange portions 103a and 103b at both ends.
Since 06 is locked to the cover 106 while being in contact with the opening end surface of the case 102, the thickness of the cover 106 is added to the thickness of the case 102 as it is.
Therefore, there is a limit to the thinning of the entire switch. Further, if the object to be detected M is charged with static electricity, the magnetic field may be disturbed by the static electricity when the object to be detected M passes through the air-core coil 104, resulting in a malfunction.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a proximity switch in which a shield plate for preventing malfunction due to static electricity can be accommodated and the overall thickness can be easily reduced. Has an aim.

[0005]

In order to achieve the above object, a proximity switch according to the present invention comprises a long box-shaped case having a through hole of a metallic object to be detected formed at one longitudinal end thereof. An air-core coil that is concentric with the passage hole and is housed in one end of the case; and a detection circuit for the object to be detected is formed together with the air-core coil and is housed in the other longitudinal end of the case. A printed wiring board and a passage hole corresponding to the passage hole on the case side are formed, and the tubular portion for winding the air-core coil is integrally formed on the inner surface to be flush with the opening end face on the other end portion side of the case. A cover covering one end side of the case, an engaging portion of the case formed on the cover and engaging with each other within a thickness range of the case, and a wide surface portion covering the printed wiring board. Above the air-core coil in the passing direction of the detected object. Side, the shield plate disposed in the case and pressed and fixed to the inner surface of the case by the tip of the tubular portion, and the printed wiring board filled in the other end portion in the longitudinal direction of the case and fixed to the mold. And a synthetic resin to be used.

Particularly, in the proximity switch having the above structure,
It is preferable to form recesses on both inner surfaces in the width direction at the other end of the case.

[0007]

According to the present invention, since the air core coil is wound around the cylindrical portion integrally formed on the inner surface of the cover covering the case,
The thickness of the case itself can be made thinner by the thickness of both the above-mentioned collars than the case where a coil spool having a collar at both ends in the axial direction is housed in the case, while the cover is opened at the other end side of the case. Since it is configured to be engaged and fixed to the case so as to be flush with the end face, it is possible to keep the total thickness to the thickness of the case, and it is possible to easily reduce the thickness of the entire switch. . Further, since the shield plate pressed by the tubular portion is disposed on the inner surface side of the case on the upstream side of the air core coil, it is assumed that the object to be detected passing through the passage hole in the case is charged with static electricity. Also, the shield action prevents malfunction of detection.

In particular, when the recesses are formed on the inner surfaces at both ends in the width direction at the other end of the case, the synthetic resin is filled into the other end in the longitudinal direction of the case to form the printed wiring board. When the mold is fixed to the mold, the synthetic resin enters the recesses, and the synthetic resin at that portion works as a locking action, so that the expansion deformation of both side walls in the width direction of the case is suppressed.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 1 and 2 are an exploded perspective view and an assembled sectional view showing a proximity switch according to an embodiment of the present invention.

In FIGS. 1 and 2, reference numeral 1 is a long box-shaped case made of an electrically insulating synthetic resin or the like, and one end portion 1a in the longitudinal direction thereof has a through hole 2 for a metallic object M to be detected. In addition, it is configured as a coil accommodating portion, and the other end portion 1b is configured as a substrate accommodating portion as described later.

Reference numeral 3 is concentric with the passage hole 2 and has the case 1
The air-core coil 4 accommodated in the coil accommodating portion 1a is a printed wiring board on which the air-core coil 3 and the circuit component P that detects the passage of the defendant detection object M are mounted.
It is housed in the housing portion 1 b of the case 1. Reference numeral 4a denotes an external connection terminal portion formed on the printed wiring board 4 and protruding to the outside from the other side opening portion 1c of the case 1.

Reference numeral 5 is a cover which covers the coil accommodating portion 1a in which a passage hole 6 corresponding to the passage hole 2 is formed, and which is made of an electrically insulating synthetic resin or the like and has an inner surface as shown in FIG. Further, a tubular portion 7 surrounding the passage hole 6 is integrally formed, and the air core coil 3 is wound around the tubular portion 7.

The coil accommodating portion 1 in the case 1
The opening end surface 1d on the a side is formed in a stepped manner by a depth corresponding to the thickness t1 of the cover 5, and when the cover 5 is mounted on the case 1 side, the outer surface of the cover 5 has the substrate accommodating portion 1b. It is configured to be flush with the opening end face 1e on the side. Grooves 8, 8 are formed along the thickness direction on the widthwise outer surfaces of the coil housing portion 1a of the case 1 respectively. Engaging protrusions 10 that engage with each other within the thickness range of the case 1 are formed on the hook-shaped portions 9 that are integrally formed as joining portions.

Reference numeral 11 denotes a shield plate disposed on the inner surface side of the case 1 upstream of the air-core coil 3 in the passage direction (arrow direction) of the object to be detected M, and corresponds to the passage hole 2. The C-shaped portion 11a and the wide surface portion 11b covering the printed wiring board 4 are provided.
When the cover 5 is engaged with the case 1, a is pressed and fixed to the inner surface of the case 1 at the tip of the tubular portion 7. Further, the wide surface portion 11b of the shield plate 11 is formed by cutting and raising a stopper piece 13 to be engaged with the cutout portion 12 of the printed wiring board 4.

Recesses 14 are formed on both inner surfaces in the width direction of the printed wiring board accommodating portion 1b in the case 1, and the printed wiring board 4 is fixed to the accommodating portion 1b by molding. Synthetic resin 15
(Fig. 6).

The proximity switch is assembled as follows. That is, first, the C-shaped portion 11 is provided in the case 1.
After housing the shield plate 11 so that a corresponds to the passage hole 2, the printed wiring board 4 is housed in the board housing portion 1b of the case 1 as shown in FIG. Is bent and locked in the notch 12. On the other hand, the air-core coil 3 is attached to the tubular portion 7 of the cover 5.
As shown in FIG. 3, after winding, the hook-shaped parts 9, 9 on the cover 5 side are respectively engaged with the engaging projections 10, 10 on the case 1 side as shown in FIG. The coil housing portion 1 a of the case 1 is covered with the cover 5. At this time, as shown in FIG.
Since the C-shaped portion 11a of No. 1 is pressed against the inner surface of the case 1, the shield plate 11 is fixed in the case 1 without rattling without using a special fixing member. Further, both coil ends 3a and 3b of the coil 3 are electrically connected to predetermined portions of the printed wiring board 4 by brazing or the like, as shown in FIG.

After that, as shown in FIG. 6, a synthetic resin 15 is placed in the substrate housing portion 1b of the case 1 to cover the cover 5 as shown in FIG.
Fill so that it is flush with the outer surface of. As a result, the printed wiring board 4 is molded and fixed in the case 1 by the synthetic resin 15, so that the protection and firm fixing of the printed wiring board 4 are simultaneously achieved. Further, since the synthetic resin 15 also enters the coil housing portion 1a, the shield plate 11 and the air-core coil 3 are more firmly fixed. Therefore, rattling of the shield plate 11 and the like due to the vibration when the detected object M hits the inner peripheral surface of the passage hole 2 is reliably prevented, and the component P of the printed wiring board 4 resonates. There is no fear of destruction. Further, when the synthetic resin 15 is filled, the synthetic resin 15 enters into the recesses 14, 14 in the case 1 and the locking action is exerted, so that both widthwise side walls of the case 1 are deformed in the expanding direction. Effectively prevented.

In the proximity switch as described above, the object M to be detected passes through the air core coil 3 through the passage hole 2 on the case 1 side. At this time, the oscillating operation in the detection circuit is stopped, whereby the passage of the detection object M is detected. In this case, since the shield plate 11 is arranged on the upstream side of the air-core coil 3, even if the object M to be detected is charged with static electricity, the detection effect is properly performed by the shield effect.

Since the air-core coil 3 is wound around the tubular portion 7 on the cover 5 side, the thickness of the both collar portions is larger than that of the coil spool having the both-end collar portions. While the thickness of the case 1 can be reduced, the cover 5 covers the coil housing portion 1a of the case 1 so as to be flush with the opening end surface 1e of the case 1 on the substrate housing portion 1b side. It is stopped within the thickness of the case 1. Therefore, it is possible to reduce the thickness of the entire switch even though the shield plate 11 is housed.

[0020]

As described above, according to the present invention, the above-mentioned object to be detected is provided by the shield plate which is located in the case upstream of the air core coil in the passage direction of the object to be detected. Is capable of performing an accurate detection operation even when it is charged with static electricity, and moreover, the cover covering one end of the case is engaged with the case so as to be flush with the opening end face of the other end, Since the air core coil is wound around the cylindrical portion provided on the inner surface, the whole switch can be made thinner than the conventional one even if the shield plate is built in.

In particular, when the recesses are formed on the inner surfaces on both sides in the width direction at the other end of the case, the synthetic resin filled in the other end of the case enters into the recess and is engaged. The stop action works, and it is possible to suppress the expansion and deformation of both side walls in the width direction of the case as much as possible.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a proximity switch according to an embodiment of the present invention.

FIG. 2 is an assembled sectional view showing the proximity switch.

FIG. 3 is an exploded perspective view showing a cover and an air-core coil.

FIG. 4 is a perspective view showing a state in which an air-core coil is wound around a tubular portion of a cover.

FIG. 5 is a perspective view showing the case with the cover attached in an inverted state.

FIG. 6 is a perspective view showing a case filled with a synthetic resin in an inverted state.

FIG. 7 is an assembled sectional view showing a conventional proximity switch.

[Explanation of symbols]

 1 case 1a one end of the case 1b other end of the case 1e other end side opening end face 2,6 through hole 3a air core coil 4 printed wiring board 5 cover 7 cylindrical part 9,10 engaging part 11 shield plate 11b shield plate Wide surface part 14 Recessed part 15 Synthetic resin M Detected object

Claims (2)

[Claims] 1. A long box-shaped case having a through hole of a metal detection object formed at one end in the longitudinal direction, and an air-core coil concentric with the through hole and accommodated in one end of the case. A printed circuit board that is housed in the other end of the case in the longitudinal direction to form a detection circuit for the object to be detected together with the air-core coil, and has a passage hole corresponding to the passage hole on the case side, A cover for integrally winding the air-core coil is formed on the inner surface and covers the one end side of the case in a state of being flush with the other end side opening end surface of the case. And an engaging portion that engages with each other within the thickness range of the case, and a wide surface portion that covers the printed wiring board, and is provided on the upstream side of the air-core coil in the passing direction of the detected object. The inner surface of the case is provided by the tip of the tubular portion disposed in the case. A shield plate that is pressed and fixed to
A proximity switch, comprising: a synthetic resin filled in the other end of the case in the longitudinal direction to fix the printed wiring board by molding. 2. The proximity switch according to claim 1, wherein recesses are formed on both widthwise inner surfaces of the other end of the case.