JPH0218885Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a display device for a limit switch.

Conventionally, this type of device used a light emitting diode 22 as an indicator light, as shown in Fig. 1, and connected it between the common terminal 12 and the normally closed terminal 14 via a resistor R. In this case, it was necessary to pay close attention to the polarity of the light emitting diode 22 when connecting it. Moreover, since the light emitting diode 22 has a polarity, it is necessary to prepare a switch with the opposite polarity depending on the direction in which the limit switch is connected to the power source. In order to eliminate this drawback, the second
As shown in the figure, there is a limit switch in which a light emitting diode 22 is connected between the output terminals of a diode bridge 10, but even if the power supply is AC, the diode bridge 10 must always be built into the limit switch, which reduces the cost. There was also a problem.

This invention attempts to overcome these conventional drawbacks, and its purpose is to enable light-emitting diodes to be lit with a simple configuration regardless of the type of power supply. Another object of this invention is to improve the mounting of the light emitting diode so that its light can be efficiently transmitted out of the housing.

In order to achieve this purpose, this idea
A plurality of light emitting diodes are connected in parallel with each other so that they have opposite polarities. In addition, these light emitting diodes are placed on a printed circuit board and housed in a light-transmitting case, and a recess into which the light emitting diode fits is provided at the bottom of the case. The light-emitting head of the light-emitting diode is fitted inside the laboratory via a translucent resin,
Furthermore, the light emitting diode is fixed by a filler with low translucency filled between the light emitting diode and the case.

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

That is, in FIGS. 3 and 4, an external plunger 3 is slidably inserted into one end of the limit switch housing 1 via a guide tube 2, and a return spring 4 provided between the plunger and the housing 1 It is always biased outward. A built-in switch 6 is housed in a switch housing chamber 5 of the housing 1, and its plunger 7
is pressed by a pusher 11 slidably guided by the external plunger 3. One end of a cable 18 is connected to the common terminal 12, normally open terminal 13, and normally closed terminal 14 of the switch 6, and the other end of this cable is connected to an AC power source or a DC power source. A translucent case 16 is attached to the other end of the housing 1 via an annular seal 17 so as to cover the opening 15 of the housing 1 . A printed circuit board 21 is housed in the case 16 made of a translucent material, and a plurality of light emitting diodes 22, 22 are arranged on this printed circuit board. A plurality of recesses 23, 23 are provided in the inner bottom of the case 16, and the light emitting heads of the light emitting diodes 22, 22 are fitted into the recesses through a resin 24 having translucency. Also, the printed circuit board 21 has a resistor 25.
is installed. and light emitting diode 22,2
2 are connected in parallel to each other so as to have opposite polarities, as shown in FIG. connected between.

Further, the switch housing chamber 5 and the case 16 are filled with a filler 27 having low translucency, thereby fixing the light emitting diodes 22 to the case 16.

In the above configuration, when the external plunger is not pressed, the movable contact 26 of the switch 6 contacts the normally closed terminal 14, thereby short-circuiting the light emitting diode 22 together with the resistor 25, so that the light emitting diode 22 is turned off. are doing. Next, when the external plunger 3 is pressed, the movable contact 26 of the switch 6 moves from the normally closed terminal 14 to the normally open terminal 1.
Flip to 3. In the case where direct current is used as the power supply, only the light emitting diodes 22, 22 connected in the forward direction emit light, and those connected in the reverse direction do not emit light. Conversely, when the polarity of the DC power source is changed, the light emission is reversed.

In addition, when alternating current is used as the power supply, light emitting diodes 22 connected with opposite polarities,
22 are lit alternately.

In the above embodiment, the case 16 was made of a translucent material.
This may be done as long as at least the portion where the light emitting diodes 22, 22 are located is translucent. Furthermore, the light emitting diodes 22, 22 have a common terminal 12 and a normally closed terminal 14.
Although the description has been made regarding the connection between the common terminal 12 and the normally open terminal 13, this may also be connected between the common terminal 12 and the normally open terminal 13. That is, it goes without saying that there is no problem as long as it is between the common terminal 12 and other terminals.

As mentioned above, this idea is based on the printed circuit board 2.
A plurality of light emitting diodes 22 are arranged on the case 16, and these light emitting diodes 22 are housed in the case 16, and the light emitting diodes 22 are connected in parallel to each other so that they have opposite polarities, and further, the light emitting diodes 22 are The diode 22 is connected between the common terminal 12 and other terminals of the switch 6 via a resistor 25, and a plurality of recesses 23 into which the light emitting diodes 22 are fitted are provided in the inner bottom of the case 16. The light-emitting head of the light-emitting diode 22 is fitted through a translucent resin 24, and the light-emitting diode 22 is further fixed to the case 16 by a filler 27 with low translucency filled in the case. Moreover, since at least the portion of the case 16 corresponding to the light emitting diode 22 is made of a transparent material, there is no need to pay attention to the polarity of the power source or the polarity of the light emitting diode, unlike in the conventional case. Furthermore, since there is no need to use a diode bridge, the limit switch can be made smaller as a whole and can be supplied at low cost. Furthermore, when the light-emitting diode 22 is turned on, the light passes through the case 16 and the resin 24, which have translucency, and is emitted to the outside of the case 16;
7 has the advantage that the contrast is large and therefore the display is easy to confirm at any time.
Moreover, the light emitting diode 22 is located in the recess 2 of the case 16.
3, the position will not shift when the filler 27 is filled.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams showing a conventional method of connecting light emitting diodes, FIG. 3 is a front sectional view showing an embodiment of the device according to this invention, FIG. 4 is a side sectional view thereof, and FIG. 5 FIG. 2 is a circuit diagram showing a connection state of light emitting diodes. DESCRIPTION OF SYMBOLS 1... Housing, 2... Guide tube, 3... External plunger, 4... Return spring, 5... Switch housing chamber, 6... Built-in switch, 7... Plunger, 11... Presser, 12... common terminal,
13... Normally open terminal, 14... Normally closed terminal, 15...
Opening, 16...Case, 17...Seal, 18
... Cable, 21 ... Printed circuit board, 22
... Light emitting diode, 23 ... Recess, 24 ... Resin, 25 ... Resistor, 26 ... Movable contact, 27 ...
filler.

Claims (1)

[Scope of utility model registration request] A plurality of light emitting diodes 22 are disposed on a printed circuit board 21, and these light emitting diodes are housed in a case 16, and the light emitting diodes 22 are connected in parallel to each other so as to have opposite polarities, Furthermore, those light emitting diodes are connected to the common terminal 12 of the switch 6 via a resistor 25.
and other terminals, while the case 16
A plurality of recesses 23 into which the light emitting diodes 22 are fitted are provided in the inner bottom of the recess, the light emitting head of the light emitting diode 22 is fitted into the recesses via a translucent resin 24, and the light emitting diode 22 is fixed to the case 16 by a filler 27 with low translucency filled in the case, and at least the light emitting diode 22 of the case 16 is fixed.
A limit switch indicator light mounting device whose corresponding parts are made of translucent material.