JPS6129160B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sealed structure of a case of a detection device for detecting the presence or absence of an object to be detected, and particularly relates to the shape of the case and packing. In the following explanation, a photoelectric switch, which is one of the detection devices, will be taken up.

Photoelectric switches are used to detect the presence or absence of light and turn on/off controlled devices such as relays, but the photodetector, amplifier circuit, switching circuit, etc. that make up the photoelectric switch are housed inside the case. In such cases, the connecting conductor for connecting electronic circuits such as amplification circuits and switching circuits housed inside the case to an external power source, etc. should be pulled out from a specified surface such as the back of the case. However, in order to improve the degree of sealing inside the case, a gap is inevitably created in the lead-out portion of the connection conductor, etc., but it is desirable to make this gap a sealed structure.

And especially the power supply of the electronic circuit mentioned above.
For photoelectric switches that can switch between 100V and 200V, or switch the output line of the electronic circuit depending on the controlled device, there are power terminals and output terminals for 100V and 200V on a specified surface such as the back of the case. However, in such a case, making each terminal group hermetically sealed from the inside of the case is problematic because the structure becomes more complicated as the number of terminals increases.

Therefore, in order to simplify the sealed structure, a sealed structure was devised in which the entire periphery of the terminal group was covered with a gasket, and this gasket was pressed and fixed with the back cover. In addition, when the back cover is removed during maintenance and inspection, the gasket may become misaligned or come off, making it difficult to attach the back cover, or the tightness of the seal may be compromised. In addition, when attaching the back cover to the case by fastening or the like, the gasket may be pressed and stretched, and the stretch may remain in one place, causing wrinkles and impairing the seal.

This invention has been proposed in view of the above, and aims to provide a photoelectric switch that prevents the seal from being misaligned, prevents the degree of sealing from deteriorating, and allows the work of attaching the back cover to be carried out efficiently. shall be.

According to this invention, when temporarily attaching the packing to the case, the recess of the case is shaped to have a long side and a short side, and the convex part of the packing is made to correspond to the long and short sides of the recess. Since the cross-sectional shape is larger than the short side of the recess and smaller than the long side of the recess, it can be held by inserting the convex part of the gasket into the recess of the case, and when attaching the case back. The packing does not fall off or become misaligned. Also, when pressing the back cover against the case and crushing the gasket, the long side of the gasket expands, but this elongation is absorbed by the convex part of the gasket that shifts its position within the long side of the recess in the case. This has the effect of preventing the packing from wrinkling in the middle of the long side and causing insufficient airtightness.

Embodiments of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 indicates a reflective photoelectric switch according to the present invention. This reflective photoelectric switch 1 includes a case 11 that houses electronic circuits such as a light emitting element, a light receiving element, an amplification circuit, and a switching circuit, and a cover 13 that closes an opening of this case 11.
It further includes a back cover 12 for covering a group of terminals provided on the back side of the case 11.

The case 11 will be explained with reference to FIGS. 2 and 3. The front of the case 11 is provided with an opening, while the back of the case 11 is provided with five terminal receiving portions 11h. be. This terminal receiving part 1
On the right side of 1h, an elongated gap 11i and a number of grooves 11K corresponding to the terminals 14 are provided. The elongated gap 11i is for inserting and holding a rear end 19a of a printed circuit board 19, which will be described later, and the groove 11K is a groove into which a tongue piece 14a of the terminal 14 is inserted. To explain the structure of the case 11 in more detail, first, a screw hole 11l is provided in the upper center of the back of the case. This screw hole 11l is for screwing the back cover 12. A hole 11e for fixing a hexagonal bolt and a through hole 11f for the bolt are provided on the side surface of the case.

With this, when installing the case 11,
Consideration has been made so that the case 11 can be attached using this hole 11f.

In addition, there are grooves 11g at the bottom of the left and right sides of the case 11.
This groove 11g is configured so that the engagement piece 12b of the back cover 12 can be engaged therewith.

Therefore, when covering the back of the case 11 with the back cover 12, first engage the engagement piece 12b of the back cover 12 with the groove 11g of the case 11, and rotate the case 12 around this engagement part. Since the back cover 12 and the back of the case can be brought into contact with each other, the screw is inserted through the hole 12C provided on the top surface of the back cover 12, and the screw is inserted into the screw hole 11 provided on the back of the case.
If you tighten and fix the screw to l, case 11
The back side is closed by a back cover 12. In reality, when covering the back of the case 11 with the back cover 12, a gasket is used to seal the case, but this point will be described later.

Note that a groove 11j is provided on the inner surface of the case 11, and this groove 11j is used for a printed circuit board 19, which will be described later.
This is for inserting the side edge of the

Now, as shown in FIG. 3, the terminal 14 is fixed in the groove 11K by inserting the tongue piece 14a of the terminal 14 into the groove 11K, and the terminal piece 14b is fixed in the groove 11K.
It protrudes downward from the notch provided on the lower side of 1K. This terminal piece 14b is electrically connected to a copper foil provided on the edge of a printed circuit board 19, which will be described later, by soldering or the like.

Note that the connection portion of the terminal 14 with the external lead wire is configured to have an inclination of about 45 degrees with respect to the tongue piece 14a.

In addition, the top surface of the case 11 has a square hole 11b and a round hole 1.
1a is provided, and a round hole 1 is also provided in the groove 11C.
1d is provided.

The round hole 11a is provided to check the display light emitting diode (to be described later) from above the case, and the square hole 11b is provided to secure the cover after inserting the cover 13 into the case opening. This is a hole provided for pouring resin or inserting an ultrasonic welder for ultrasonic welding.

The round hole 11d is a hole provided so that a knob of a sensitivity adjustment volume (not shown) of an electronic circuit housed in the case can be operated from the outside.

The wide groove 11C is a groove for pasting a label on which a product name, company name, trademark, etc. are printed.

Furthermore, as explained with reference to Figures 4, 5, and 6,
In FIG. 4, 15 is an electronic circuit section of a reflective photoelectric switch, and 16 is an optical hood in which a light projecting hood and a light receiving hood are integrally molded with resin.

This optical hood 16 is placed on a printed circuit board 19, and its collar is in contact with the front edge of the printed circuit board 19. Reference numeral 17 designates electronic components such as IC circuits, transistors, capacitors, and resistors that constitute electronic circuits such as an oscillation circuit 61, an amplification circuit 62, a detection circuit 63, a switching circuit 64, and a knot circuit 65 as shown in FIG. be. Further, 18 is a light emitting diode for displaying operation. Note that 64a is an output terminal that generates an on output when an object is present, and 65a an output terminal that generates an OFF output.

As shown in FIG. 5, the above-mentioned optical hood 16 includes a light receiving hood 16a, a light emitting hood 16b,
The collar portion 16g is formed by resin molding.

A hole is provided at the rear end base of the light-receiving hood 16a, and a light-receiving element 20 such as a photo diode is fixed in this hole. This light receiving hood 16a
Since the hood 16a is sloped from the rear end base to the opening, the hood 16a has a substantially conical shape. A hole is also provided at the rear end base of the light projecting hood 16b, and a light projecting element 21 such as a light emitting diode is fixed in this hole.

The outer shape of the light projection hood 16b is also sloped from the base to the opening 16e, forming a conical shape, but the outer side wall is removed and the opening 16e
C, the shape of the optical hood 16 is reduced accordingly.

Now, to briefly explain an example of the assembly process of the reflective photoelectric switch according to this embodiment, first, a predetermined electronic component 17 is mounted on a printed circuit board 19, and then a light emitting element 21 and a light receiving element 20 are respectively fixed. A hood 16 is prepared, and the lead wires 21a and 20a of the light emitting element and the light receiving element fixed to the optical hood are wired to the printed circuit board 19,
The optical hood 16 is placed on the printed circuit board, and the flange 16g of the optical hood 16 is brought into contact with the front edge of the printed circuit board 16. At this time, the display light emitting diode 18 is connected to the flange 16g of the optical hood.
(see Fig. 4).

Next, the cover 13 provided with the lenses 13a and 13b is engaged with the optical hood 16. At this time cover 1
The grooves 13e provided on both sides of the cover engage with the protrusions 16d provided on the optical hood, and the top of the display light emitting diode 18 is inserted into the hole 13d provided on the back surface of the upper end 13C of the cover.

Thereafter, while making sure that the cover 13 does not come off the printed circuit board 19, insert the printed circuit board 19 into the case while aligning the side edge of the printed circuit board 19 with the groove 11j provided in the case, and insert the printed circuit board 19 into the case so that the rear end 19a of the printed circuit board 19 is aligned.
into the wide groove 11i provided at the rear end of the case.

By doing this, the rear end 1 of the printed circuit board
9a protrudes somewhat from the back of the case, and the rear end 19
The groove 19b provided in the terminal a is engaged with the terminal piece 14b of the terminal 14. Electrical connection is made by connecting this terminal piece 14b to a copper foil provided around the groove 19b by soldering or the like.

On the other hand, the cover 13 and the opening of the case 11 can be sealed by ultrasonic welding or the like as described above.

Each component is mounted and assembled inside the case 11 as described above, but there is an electrical connection between the output line or power supply line of the electronic circuit inside the case 11 and the external controlled device or power supply. However, since the lead wire for this connection is drawn out from the inside of the case 11, a gap is created in that part, and it is therefore necessary to seal this gap. In particular, when a plurality of terminals are provided on the back side of the case 11 as in this embodiment, if each terminal part is sealed separately, the structure becomes extremely complicated and the number of parts increases, resulting in an assembly process. It is expected that this will be extremely troublesome. Therefore, one feature of this embodiment is that the terminal group can be hermetically sealed all at once, as shown in FIG. As for the structure of the packing, a rectangular ring-shaped packing 71 made of an elastic body is used.
While a circular protrusion 71a is provided at the corner, case 1
A rectangular hole 72 is provided at a position corresponding to the protrusion 71a on the back side of 1, and the short side of the rectangular hole 72 is smaller than the diameter of the protrusion 71a, and the long side is the same as the protrusion. The diameter should be larger than that of 71a. Then, when the protrusion 71a of the gasket 71 is inserted into the hole 72 provided on the back surface of the case 11, the gasket 71 is held. Moreover, since the long side of the hole 72 is larger than the diameter of the protrusion 71a and the short side is shorter than the diameter of the protrusion 71a, when inserting the packing 71 into the protrusion 71a, since the protrusion 71 is an elastic body, Since an escape area is secured on the long side of the hole 72, the insertion work is easy to perform.

Moreover, since the gasket 71 is held on the back of the case in this way, when the back cover 12 is attached to the back of the case, the position of the gasket does not shift at this time, making the back cover installation process easy and secure. This has the effect of sealing the inside of the case.

In the above embodiments, an example of a reflective photoelectric switch is described in which a plurality of terminal groups are provided on the back of the case, but the present invention is not necessarily limited to this. It can also be used in photoelectric switches with only wires, and the shape of the gasket is not necessarily limited to a rectangular shape.

Furthermore, the location to be sealed is not limited to the back surface, but may be any location where lead wires and terminal wires are provided.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of the external shape of a reflective photoelectric switch according to an embodiment of the present invention, FIG. 2 a is a rear view of the case 11 shown in FIG. 1, b is a side view of the case, C is a front view of the case, FIG. 3 is a partially cutaway perspective view showing the top and back surfaces of the first illustrated case 11, FIG. 4 is a side view of printed circuit boards etc. stored in the first illustrated case, and FIG. 5 is an optical hood. 6 is a block diagram of the reflective photoelectric switch, and FIG. 7 is a partially simplified perspective view of the back cover shown in FIG. 1 with the back lid gasket removed. 20; Light-receiving element, 21; Light-emitting element, 17; Electronic circuit, 71; Packing, 71a; Protrusion of packing, 72; Recess on back of case, 11; Case.

Claims (1)

[Claims] 1. An electronic circuit consisting of a detection circuit for detecting an object to be detected, an amplifier circuit for amplifying the output of this detection circuit, and a switching circuit for switching according to the output of this amplifier circuit; A case that houses a circuit, a back cover that covers a predetermined surface of the case, a lead wire pulled out from a predetermined part of the back cover and connected to the electronic circuit, and an elastic body interposed between the case and the back cover. In the detection device, the predetermined surface of the case has a rectangular shape having a long side and a short side, and a long side and a short side corresponding to the long side and short side are formed at a predetermined location. The packing has a plurality of concave portions at positions corresponding to the concave portions, and the cross-sectional shape of the convex portions is larger than the short side dimension of the concave portions. A detection device characterized in that the size is smaller than the long side.