JPH0617064U - Limit switch - Google Patents

Abstract

(57) [Abstract] [Purpose] It is intended to provide a limit switch in which an indicator lamp lights when a contact is "closed". A pair of normally open contacts and a pair of normally closed contacts are provided, and a power supply is provided between one contact of the pair of normally open contacts and one contact of the pair of normally closed contacts. A load is connected, and a display circuit having a display element and a constant current element is connected between the connected pair of contacts and the other pair of contacts not connected to the load having the power source. Is a structural feature.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a limit switch, and more particularly to a limit switch having an indicator light circuit.

[0002]

[Prior art]

 FIG. 8 is a front view showing an external configuration of a conventional limit switch. 9 is a partial cross-sectional view of the right side surface of the limit switch body portion shown in FIG.

In FIG. 8, 51 is a limit switch body, 52 is a cover, 53 is a roller lever, 54 is a roller rotatably attached to the tip of the roller lever 53, and 55 is an indicator lamp. In FIG. 9, 56 is a rotary shaft to which the roller lever 53 is fixed, and 57 is a switch section having a pair of normally open contacts and a pair of normally closed contacts.

FIG. 10 is a wiring diagram of the indicator light circuit in the conventional limit switch described above.

In FIG. 10, 61 and 62 are a pair of normally open contacts, 63 and 64 are a pair of normally closed contacts, and 65 is a movable contact. 66 is a power supply and 67 is a load.

Reference numeral 68 is a rectifying stack, the input side of which is connected to the pair of normally open contacts 61 and 62, while the output side of which is a series circuit of a light indicator 55 and a current limiting resistor 70. It is connected.

In such a conventional limit switch, when the movable contact 65 is located on the normally closed contacts 63 and 64 side, the load 67, the indicator lamp 55 and the current limiting resistor 70 are connected to the power source 66. Since they are connected in series, the indicator lamp 55 lights up.

Further, when the movable contact 65 is located on the side of the normally open contacts 61 and 62, the series circuit of the indicator lamp 55 and the current limiting resistor 70 has no voltage, and the indicator lamp 55 is turned off.

As described above, the conventional limit switch is a so-called contact open lighting type in which the indicator lamp 55 is lit when the contact to which the load 67 is connected is open.

[0010]

[Problems to be solved by the device]

 While the conventional limit switch is configured so that the indicator light is turned on when the contacts are opened as described above, other proximity switches and photoelectric switches used in factory lines and machines have contacts It is confusing because the indicator light is lit when it is "closed," and it was desired to unify the conditions for turning on and off the indicator lights of these limit switches, proximity switches, and photoelectric switches.

That is, it will not be confusing if all limit switches, proximity switches, and photoelectric switches used in factory lines and machines are unified so that the indicator lights are lit when the contacts are “closed”.

Therefore, as shown in FIG. 11, an indicator lamp circuit that uses one of the pair of normally closed contacts 63 and 64 as a relay terminal and that constitutes an indicator lamp by an anti-parallel circuit of the light emitting diodes 55a and 55b is used. Although conceivable, there is a problem that the light emitting diode of the indicator lamp is destroyed when the load current of the load 67 is large.

Further, as shown in FIG. 12, it is conceivable to connect the current limiting resistor 71 to the light emitting diodes 55a and 55b of the indicator lamp, but in such a configuration, the voltage drop in the current limiting resistor 71 becomes large and the load is reduced. There is a problem that it hinders the opening and closing of 67.

The present invention has been made in view of such conventional problems, and an object thereof is to provide a limit switch that lights an indicator lamp when a contact is “closed”.

[0016]

[Means for Solving the Problems]

 The limit switch of the present invention comprises a pair of normally open contacts and a pair of normally closed contacts, and is provided between one contact of the pair of normally open contacts and one contact of the pair of normally closed contacts. A load having a power source is connected to the display, and a display element and a constant current element are provided between the contact of one connected pair and the contact of the other pair not connected to the load having the power source. The feature of the configuration is that the circuits are connected.

[0017]

[Action]

 In the limit switch according to the present invention, the indicator lamp lights up when the contacts are closed. Therefore, since the conditions for turning on and off the indicator lights of other proximity switches, photoelectric switches and the like are matched, it is not confusing to be unified with other proximity switches and photoelectric switches and the like.

[0018]

【Example】

 The invention will be described below with reference to the drawings.

FIG. 1 is a front view showing an external configuration of a limit switch according to an embodiment of the present invention. FIG. 2 is a partial cross-sectional view of the right side surface of the limit switch body portion shown in FIG.

In FIG. 1, 1 is a limit switch body, 2 is a cover, 3 is a roller lever, 4 is a roller rotatably attached to the tip of the roller lever 3, and 5 is an indicator lamp, which is composed of a light emitting diode. Has been done. In FIG. 2, 6 is a rotary shaft to which the roller lever 3 is fixed, and 7 is a switch unit having a pair of normally open contacts and a pair of normally closed contacts.

FIG. 3 is a wiring diagram showing the configuration of the indicator lamp circuit in the limit switch of this embodiment, which is a circuit for lighting the indicator lamp when the normally closed contact 13 and the normally closed contact 14 are closed.

In FIG. 3, 11 and 12 are a pair of normally open contacts, and the normally open contact 11 is used as a relay terminal. 13 and 14 are a pair of normally closed contacts. Reference numeral 15 is a movable contact. Reference numeral 16 is a power source and 17 is a load. The normally open contact 11 is connected to the power supply 16 via the load 17, and the normally closed contact 14 is also connected to the power supply 16.

A rectifying stack 19 is connected to the normally open contact 11 and the normally closed contact 13 on the input side. 20 is a resistor, 21 is a Zener diode, and 22 and 23 are constant current diodes.

The indicator lamp 5, the rectifying stack 19, the resistor 20, the Zener diode 21, and the constant current diodes 22 and 23 are housed in a holder 24.

The holder 24 can be rotated 180 °, and by rotating 180 °, the wiring L1 can be connected to the normally open contact 11 or the connection change to the normally open contact 12, and further the wiring can be changed. L2 can be connected to the normally closed contact 13 or can be reconnected to the normally closed contact 14.

FIG. 5 is a front view showing the configuration of the switch portion 7 provided inside the limit switch body, and FIG. 6 is a bottom view thereof.

In FIGS. 5 and 6, 11 a is a screw electrically connected to the normally open contact 11, 12 a is a screw electrically connected to the normally open contact 12, and 13 a is an electrically connected to the normally closed contact 13. And a screw 14a electrically connected to the normally closed contact 14. Reference numeral 25 denotes a coil spring used for electrical connection with the limit switch body side. The coil spring 25 can be replaced with a lead wire.

Next, the operation will be described.

As shown in FIG. 3, when the movable contact 15 is located on the normally closed contacts 13 and 14 side, the normally closed contacts 13 and 14 are short-circuited. As a result, the load current flows from the normally open contact 11 to the rectifying stack 19 to the indicator lamp 5 to the constant current diodes 22 and 23 to the rectifying stack 19 to the normally closed contact 13 to the normally closed contact 14 to the power source 16, and the indicator lamp 5 lights up. To do.

In this case, the potential on the anode side of the indicator lamp 5 is kept at the Zener voltage of the Zener diode 21 by the resistor 20 and the Zener diode 21. Further, since the constant current diodes 22 and 23 are connected to the cathode side of the indicator lamp 5, the current value flowing through the indicator lamp 5 becomes a constant value, and the indicator lamp 5 is limited so that an overcurrent does not flow. .

Next, when the movable contact 15 is positioned on the side of the normally open contacts 11 and 12, the normally closed contacts 13 and 14 are opened, and as a result, the load current stops flowing and the indicator lamp 5 also Turn off the light.

FIG. 4 is a wiring diagram showing the configuration of the indicator light circuit that lights the indicator light when the normally open contact 11 and the normally open contact 12 are closed. In order to change to this circuit, the wiring L1 on the input side of the rectifying stack 19 connected to the normally open contact 11 shown in FIG. 3 is changed to the normally open contact 12 as shown in FIG. Further, the connection L2 on the input side of the rectifying stack 19 connected to the normally closed contact 13 shown in FIG. 3 is changed to the normally closed contact 14 as shown in FIG.

When the wiring is changed in this way, when the movable contact 15 is located on the normally open contacts 11 and 12 side and the normally open contacts 11 and 12 are short-circuited, the load current changes from the normally open contact 11 to the normally open contact 12 -> Rectifying stack 19-> indicator light 5-> constant current diodes 22, 23-> rectifying stack 19-> normally closed contact 14-> power supply 16 and the indicator lamp 5 is turned on.

When the movable contact 15 returns to the normally closed contacts 13 and 14, the normally open contact 11 and the normally open contact 12 are opened, and as a result, the load current stops flowing and the indicator lamp 5 is also turned off.

The circuit shown in FIG. 3 is changed to the circuit shown in FIG. 4 by rotating the holder portion of the indicator lamp 180 by 180 ° so that the wiring L1 is connected from the normally open contact 11 to the normally open contact 12. The connection is changed and the wiring L2 is changed from the normally closed contact 13 to the normally closed contact 14.

Although the normally open contact 11 or the normally closed contact 14 is used as the relay terminal in the above-described embodiment, the normally open contact 12 or the normally closed contact 13 may be used as the relay terminal.

Further, when the power supply voltage of the power supply 16 is stabilized and maintains a predetermined value, the resistor 20 and the Zener diode 21 are unnecessary.

FIG. 7 is a wiring diagram showing an indicator light circuit in another embodiment of the limit switch of the present invention.

In FIG. 7, parts that are the same as or equivalent to those in FIG. 3 are assigned the same reference numerals and explanations thereof are omitted.

In this embodiment, the normally closed contact and the normally open contact are composed of three terminals, that is, the common terminal 31, the normally closed terminal 32, and the normally open terminal 33, and the common terminal 31 and the normally closed terminal 32 or the common terminal 31 are The normally open terminal 33 is connected by the movable contact 34.

Further, a relay terminal 35 is provided, the wiring L 1 to the rectifying stack 19 is connected to the normally open terminal 33, and the wiring L 2 is connected to the relay terminal 35. The load is connected to the common terminal 31 and the relay terminal 35.

With this structure, when the movable contact 34 closes the common terminal 31 and the normally open terminal 33, the indicator lamp 5 is turned on. When the wiring L1 is connected to the normally closed contact 32, the indicator light 5 is turned on when the movable contact 34 closes the common terminal 31 and the normally closed terminal 32.

[0043]

[Effect of device]

 As described above, according to the present invention, since the indicator light is turned on when the contacts are in the closed state, it is consistent with the lighting and extinguishing conditions of the indicator lights such as other proximity switches and photoelectric switches. , It has the effect of being unified with other proximity switches, photoelectric switches, etc. so that it will not become confusing when used.

[Brief description of drawings]

FIG. 1 is a front view showing an external configuration of a limit switch according to an embodiment of the present invention.

FIG. 2 is a partial sectional view of a right side surface of a limit switch body portion.

FIG. 3 is a wiring diagram showing a configuration of an indicator light circuit configured to light an indicator light when a normally closed contact is closed.

FIG. 4 is a wiring diagram showing a configuration of an indicator light circuit configured to light an indicator light when a normally open contact is closed.

FIG. 5 is a front view showing a configuration of a switch portion provided inside the limit switch body.

FIG. 6 is a bottom view showing the configuration of a switch portion provided inside the limit switch body.

FIG. 7 is a wiring diagram showing a configuration of an indicator light circuit in another embodiment of the limit switch of the present invention.

FIG. 8 is a front view showing an external configuration of a conventional limit switch.

FIG. 9 is a partial sectional view of a right side surface of a conventional limit switch body.

FIG. 10 is a wiring diagram showing an indicator light circuit in a conventional limit switch.

FIG. 11 is a wiring diagram showing a conventional indicator light circuit that is designed so that the indicator light is turned on when the contacts are closed.

FIG. 12 is a wiring diagram showing a conventional indicator light circuit that is designed so that the indicator light is turned on when the contacts are closed.

[Explanation of symbols]

 1 Limit switch body 5 Indicator lamp 11,12 Normally open contact 13,14 Normally closed contact 16 Power supply 17 Load 22 Constant current diode

Claims (1)

[Scope of utility model registration request] 1. A pair of normally open contacts and a pair of normally closed contacts are provided,
A load having a power source is connected between one contact of the pair of normally open contacts and one contact of the pair of normally closed contacts,
A limit switch in which a display circuit including a display element and a constant current element is connected between the connected pair of contacts and the other pair of contacts to which the load having the power source is not connected.