JPH0132391Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Target Technical Field] This invention relates to a shielding device for a photoelectric switch.

[Prior art and its problems]

Conventionally, this type of shielding device has conductive metal plates 15, 15 disposed on the inner circumferential surface of the case as shown in FIG. However, the processing of the metal plates and their arrangement were complicated, resulting in extremely poor work efficiency, and there was also a risk that the metal plates would separate from the case due to vibrations.

〔the purpose〕

This invention aims to eliminate such conventional drawbacks and obtain a shielding device with good working efficiency and high reliability.

〔Example〕

An embodiment of this invention will be described below with reference to the drawings.

That is, in FIGS. 1 to 4, a case 1 is formed by case parts 3 and 4 that are divided into substantially symmetrical parts along its axis. A conductive metal thin film layer 5 is formed on the inner wall surface of these cases. First side wall 6 of case 1
A window 7 is formed across both case parts 3 and 4, a lens plate 9 and a holder 10 are fitted into this window, and a light emitting element 11 is fitted into this holder.
and the light receiving element 12 is held. Moreover, a conductive metal thin film layer 15 is formed on the outer periphery of the holder 10. A printed circuit board 16 forming an electronic circuit is housed within the housing 1 . An elastic, conductive first contact 17 is fixed to this printed circuit board. This contact is formed by bending a strip of metal,
The intermediate portion thereof has a U-shaped bent portion 18 that is fitted to the printed circuit board 16 so as to sandwich it, and this bent portion is soldered to the ground conductor of the printed circuit board 16. Both end portions extend in a direction away from the printed circuit board 16 and are bent to face each other, and a reinforcing rib 20 is provided on the support portion 19 extending downward.
With both case parts 3 and 4 assembled together, one free end 21 of the contact 17 is attached to the metal thin film layer 5 of one case part 3, and the other free end 22 is attached to the other case part 4. The metal thin film layer 5 is made to come into elastic contact with each other. Further, a contactor 23 shown in FIG. 2 is fixed to the inner wall of one of the case parts 3 adjacent to the window 7 by guide bosses 25, 25 of the case part 3. This contact is formed by punching an elastic metal plate, and its free end extends in a direction away from the wall surface of the case part 3. It is adapted to be in electrical contact with the metal thin film layer 15 of the holder 10.
Note that this second contact may be fixed to the other case part 4 or the holder 10, in other words, if it is provided between the holder 10 and the case 1 and short-circuits both the metal thin film layers 5 and 15. good.

[Effect]

Then, when the holder 10 is fitted into the case parts 3 and 4 and both the case parts 3 and 4 are assembled, the metal thin film layers 5 and 5 of these case parts and the metal thin film layer 15 of the holder 10 are both printed. It is electrically connected to the ground conductor of the circuit board 16 to provide electromagnetic shielding.

〔effect〕

As mentioned above, this idea provides a conductive thin film layer on the inner wall of the case and the outer periphery of the holder.
A printed circuit board housed in the case has an elastic conductive first contact electrically connected to the ground conductor of the board and a free end thereof in contact with a conductive thin film layer of the case. Furthermore, a second contact is provided between the case and the holder to short-circuit the metal thin film layer of the holder and the metal thin film layer of the case, so that not only the electronic circuit but also the electromagnetic Can do shield.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view showing one embodiment of the shielding device of this invention, Fig. 2 is a plan view showing a part of the case cut away, and Fig. 3 is shown along line 3-3 in Fig. 2. Front sectional view, Figure 4 is 4-4 in Figure 2
FIG. 5 is a side sectional view taken along the line, and FIG. 5 is a side sectional view of a conventional device. 1 is the case, 3 is the case part, 4 is the case part, 5
is a metal thin film layer, 7 is a window, 9 is a lens plate, 1
0 is a holder, 11 is a light emitting element, 12 is a light receiving element, 15 is a metal thin film layer, 16 is a printed circuit board, 17 is a first contact, 18 is a bent part, 19
20 is a rib, 21 is an automatic end, 22 is a free end, 23 is a second contact, and 25 is a guide boss.

Claims (1)

[Claims for Utility Model Registration] (1) A case housing a printed circuit board constituting a switching circuit is formed by a pair of case parts divided along the axis thereof, and a window is provided in the side wall of the case, In a device in which a holder for holding a light emitting element or a light receiving element is attached to the window, a conductive thin film layer is provided on the inner wall surface of the case and the outer periphery of the holder, and an elastic conductive layer is provided on the printed circuit board. 1 is fixed in a state where it is electrically connected to the ground conductor of the board, and its both ends are extended away from both sides of the board, and its free ends are connected to the conductive thin films of both case parts. an elastic conductive second contact between the case and the holder to bring the conductive thin film layer of the holder into electrical contact with the conductive thin film layer of the case; A shield device for a photoelectric switch equipped with a shield. (2) The shield device for a photoelectric switch according to claim 1, wherein the second contact is fixed to the case. (3) The shield device for a photoelectric switch according to claim 1, wherein the second contact is fixed to the holder.