JPH0887936A - Steel ball detecting switch - Google Patents

Abstract

PURPOSE: To stabilize a passing speed of a steel ball so as to detect it by high detecting efficiency, in a steel ball detecting switch of detecting the steel ball to pass. CONSTITUTION: A sectional shape of a through hole, making a steel ball 20 pass, is formed in a polygonal shape, to constitute a curved part. A radius of curvature of this curved part is set less than a radius of the steel ball. In this way, the steel ball 20 is brought into contact with an internal surface of the through hole in two points C, D, to stabilize a passing speed. A coil 3 can be placed to approach the steel ball, to enable efficiency to improve of detecting the steel ball.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a steel ball detecting switch for detecting the number of steel balls such as pachinko balls.

[0002]

2. Description of the Related Art A high-frequency oscillation type proximity switch is generally used as a sensor for magnetically detecting the presence of metal in a non-contact manner. Among such proximity switches, in order to detect steel balls such as pachinko balls, there is a penetration type steel ball detection switch that outputs an electric signal every time a metal ball passes through a cylindrical coil. Are known. Such a steel ball detection switch is provided with a coil spool having a through hole through which the steel ball passes as a central hole, and a coil is wound around the coil spool to form an oscillation circuit together with the coil. A steel ball is detected by a change in state.

However, in such a conventional steel ball detecting switch, the steel ball falls straight and quickly without coming into contact with the inner wall of the through hole, or slowly falls while spirally rolling along the inside of the gap. Then, there was a difference in passing speed. Further, the steel balls collide with each other in the through hole to bounce, and one steel ball may pass twice, resulting in erroneous detection. Therefore, in order to eliminate such a defect, in Japanese Utility Model Publication No. 2-31714, the cross-sectional shape of the through hole is not a circle but a polygon. In this way, the steel balls can be brought into contact with each other at two points on the inner wall of the through hole, the movement of the steel balls can be stabilized quickly, and the passing speed of the steel balls can be kept substantially constant to eliminate erroneous detection.

[0004]

If the coil wound along the through hole is mounted as close as possible to the steel ball, the amount of change in conductance increases and the variation in the detection distance can be reduced. Therefore, the more the through hole becomes a quadrangle or a triangle and the polygon with a small number of small sides, the faster the movement of the steel ball can be stabilized, but the coil wire becomes far from the steel ball. Further, if the polygon has a large number of sides, the stability of the movement of the steel ball becomes poor, but since the coil wire approaches the steel ball, the detection efficiency can be improved.

The present invention has been made in order to satisfy the contradictory requirements of the prior art, and it is an object of the present invention to stabilize the passing speed of steel balls and to detect steel balls with high detection efficiency. To do.

[0006]

The present invention relates to a cylindrical coil, an oscillating circuit having the cylindrical coil as an oscillating coil, and a metal body passing through the inside of the cylindrical coil based on a change in an oscillating state of the oscillating circuit. A steel ball detection switch having a signal processing unit for detecting a case, and a case having a shaft portion of a cylindrical coil as a through hole, the through hole of the case having a polygonal cross section, and each vertex of the through hole. A curved portion having a radius of curvature smaller than the radius of the steel ball passing through the through hole is provided in the.

[0007]

According to the present invention having such a feature, since the cross-sectional shape of the through hole through which the steel ball passes is polygonal and a curved portion having a radius equal to or smaller than the radius is provided at the apex, the steel ball penetrates the polygonal hole. The two points on the wall surface of the hole come into contact with each other, so that the passing speed becomes stable. Further, by providing the curved portion, the diameter of the coil can be reduced, and the sensitivity of passage detection can be improved.

[0008]

EXAMPLE A steel ball detecting switch for detecting penetration of a pachinko ball according to an embodiment of the present invention will be described. 1 is a front view of the steel ball detection switch with the upper case removed,
FIG. 2A is a sectional view taken along the line AA with the upper case attached, and FIG. 2B is a sectional view taken along the line BB. FIG. 3 is an assembly configuration diagram of a steel ball detecting switch according to this embodiment. As shown in these figures, this steel ball detection switch
The lower case 1 and the upper case 2 constitute a flat rectangular parallelepiped case. A substantially circular through hole is formed in this housing as shown in the figure. The upper and lower cases 1 and 2 each have a protrusion having a claw on its outer peripheral portion and a notch portion that engages with the claw, and the casing is configured by engaging these. As shown in FIG. 3, the lower case 1 is provided with an opening 1a, and a pin 1b is provided upward from the lower base thereof.
Furthermore, the left and right sidewalls of the pin 1b of the lower case 1 are formed with recesses 1c and 1d for holding projections of a printed circuit board, which will be described later. An opening 2a is formed in the upper case 2 at a position facing the opening 1a. Through the openings 1a and 2a, a through hole for passing a steel ball is formed in the case.

Now, between these upper and lower cases 1 and 2,
Components including the coil 3 and the printed circuit board 4 are mounted.
As shown in the figure, the coil 3 is configured such that a coil winding is wound around a coil spool 5 a predetermined number of times, and the ends thereof are wound around protrusions 4 a and 4 b provided on the left and right of the printed circuit board 4. The printed circuit board 4 has a pin 1 in the middle of the protrusions 4a and 4b.
There is an opening 4c that engages with b, and an elongated slit 4d is formed on the right side thereof. An electronic circuit section of a steel ball detection switch is mounted on the printed board 4. The coil spool 5 is a cylindrical member formed with a through hole having an inner diameter substantially equal to the openings 1a and 2a of the cases 1 and 2, and has a pair of upper and lower holding portions 5 at its right end as shown in the drawing.
a and 5b are formed. The distance between the holding portions 5a and 5b is substantially equal to the thickness of the printed circuit board 4, and the opening 4c of the printed circuit board 4 is fixed so that part of the opening 4c is aligned with the semicircular cutout of the upper holding portion 5a. . The lower holding portion 5b projects rightward from the upper holding portion 5a, and an opening is formed at a position corresponding to the opening 4c. In addition, the left end surface of the printed circuit board 4 constitutes the side wall of the opening 1a,
A slit (not shown) is formed on the coil spool 5. Shield rings 6 and 7 are fixed above and below the coil 3 at positions fitted to the coil spool 5. The shield rings 6 and 7 are metal ring-shaped members made of, for example, a copper foil plate, and are configured so that they are combined to cover the outer peripheral portion of the coil 3. Shield ring 6
3 and 7, the left and right portions shown in FIG. 3 are thinly cut out, of which the right-side cutout portion of the shield ring 6 has an upward projection 6a and the right-side cutout portion of the shield ring 7 has a downward projection 7a. To be done. These protrusions 6a and 7a
Are configured to face each other via the slit 4d of the printed circuit board 4. Now, in the first embodiment, as shown in FIG.
As shown in (b), plastic ferrites 8 and 9 are formed inside the shield rings 6 and 7 by insert molding. The plastic ferrites 8 and 9 are magnetic materials having high magnetic permeability, and form magnetic paths of a magnetic circuit.

FIG. 4 is a block diagram showing the circuit configuration of the steel ball detection switch according to this embodiment. An oscillation circuit 11 is connected to both ends of the coil 3 as shown in the figure. The oscillating circuit 11 is a circuit using the coil 3 as an oscillating coil, oscillates at a constant frequency, and its output is transmitted to the detecting circuit 12. When a steel ball passes through the coil 3, the conductance of the coil increases, the oscillation condition of the oscillation circuit 11 changes, the amplitude decreases, or the oscillation stops. The detection circuit 12 detects the output of the oscillation circuit 11, detects an object when the oscillation level becomes less than or equal to a predetermined threshold value, and outputs a steel ball detection signal via the output circuit 13 to detect the steel ball. Passage can be detected. The detection circuit 12 and the output circuit 13 configure a signal processing unit that detects the proximity of the steel ball based on the change in the oscillation state.

In this embodiment, the through-holes through which the steel balls pass are substantially octagonal as shown in FIG. 1, and a curved portion R is provided on the outer periphery thereof. FIG. 5 (a) is an enlarged view showing this through hole, and FIG. 5 (b) is a view shown for comparison with the through hole in the case where no curved portion is provided.
If the steel ball to be detected as shown in this figure, here the steel ball is a pachinko ball 20, its diameter is 11 mm. Therefore, the diameter of the inscribed circle of the through hole for detecting this steel ball is also set to a value slightly larger than this, for example, in the range of 11.6 to 11.8 mm, here 11.7 mm. Then, as shown in the figure, an octagonal cross section is formed, and a curved portion is formed at the apex portion thereof. The radius of curvature of this curved portion is 5.5 mm which is the radius of the pachinko ball 20 to be detected.
A slightly smaller value, for example in the range of 4-5 mm, was selected here as 4 mm. By doing so, it is possible to reduce the wall thickness of the coil spool during molding as compared with FIG. 5B and bring it closer to the pachinko ball 20 for detecting the coil winding itself, and the detection efficiency is improved. Therefore, the passage of the steel ball can be reliably detected without the risk of erroneous detection. Further, since the through-hole has an octagonal cross-sectional shape, and the radius of curvature of the curved portion provided at the apex of the through-hole is less than or equal to the radius of the steel ball, the steel ball has two points C and D on the inner wall of the through-hole. Therefore, the passing speed of the steel balls can be stabilized.

In this embodiment, the curved portion is formed at the apex of the through-hole having a regular octagonal cross section, but the shape is not limited to an octagon, but may be any shape such as a quadrangle, a hexagon or a polygon within the range. You can choose. The diameter of the through hole is slightly larger than this, and for example, for pachinko balls, 11.5 to 11.9 mm can be selected. The radius of curvature of the curved portion is less than half the radius of the penetrating steel ball. The outer shape of the through hole is preferably a regular pentagon to a regular octagon, the diameter of the inscribed circle is 105 to 107% of the diameter of the steel ball, and the radius of curvature is 36 to 45% of the diameter of the steel ball. In this way, the passage of the steel balls can be stabilized, and the passage can be detected with high efficiency.

[0013]

As described in detail above, according to the present invention, the steel balls are in contact with each other at two points and the curved portion having the curvature radius less than the radius of the sphere is provided. As a result, the effect of stabilizing the passage of the steel ball and enabling highly efficient detection can be obtained.

[Brief description of drawings]

FIG. 1 is a front view of a steel ball detection switch according to an embodiment of the present invention, excluding an upper case.

2A is a sectional view taken along the line AA of the switch for detecting a steel ball, and FIG. 2B is a sectional view taken along the line BB.

FIG. 3 is an assembly configuration diagram of a steel ball detection switch according to the present embodiment.

FIG. 4 is a block diagram showing a configuration of a steel ball detection switch according to the present embodiment.

5A is a partially enlarged view showing a portion of a through hole of the present embodiment, and FIG. 5B is a partially enlarged view of a through hole when a curved portion is not provided.

[Explanation of symbols]

 1 Lower case 2 Upper case 3 Coil 4 Printed circuit board 5 Coil spool 6,7 Shield ring 8,9 Plastic ferrite 11 Oscillation circuit 12 Detection circuit 13 Output circuit 20 Pachinko ball

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Toru Aoki, Tohru Aoki, Kyoto, Kyoto Prefecture, 10th Hanazono Todocho, Ukyo-ku, Kyoto Omron Co., Ltd. Within the corporation

Claims (3)

[Claims] 1. A cylindrical coil, an oscillating circuit using the cylindrical coil as an oscillating coil, and signal processing for detecting a metal body passing through the inside of the cylindrical coil based on a change in an oscillating state of the oscillating circuit. And a case having a shaft portion of the cylindrical coil as a through hole, wherein the through hole of the case has a polygonal cross section, and penetrates at each vertex of the through hole. A switch for detecting a steel ball, comprising a curved portion having a radius of curvature smaller than a radius of the steel ball passing through the hole. 2. The through hole of the case has a pentagonal to octagonal cross-sectional shape, and the diameter of the inscribed circle of the polygon is 105 to the diameter of the steel ball.
The range of 107%, and the radius of curvature of the curved portion is 36 to 45% of the diameter of the steel ball.
The steel ball detecting switch according to claim 1, wherein 3. The steel ball is a steel ball having a diameter of 11 mm, the polygon has an octagonal shape, the inscribed circle diameter is 11.7 mm, and the radius of curvature of the curved portion is 4 mm. The switch for detecting a steel ball according to claim 2.