JPS58500581A - proximity switch - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] "Proximity switch" explanation The present invention relates to a proximity switch, in particular a switch circuit including an oscillator and an induction coil. Proximity switches actuated by a metal object in close proximity to the switch that changes the oscillation. It is related to

This membrane type switch is well known in the art and works well. However, this To economically manufacture these switches to give good uniformity, several There is a problem. The induction coil used is rather sensitive, both electrically and mechanically. It is. In order to obtain high sensitivity, thin wires that are easily damaged during switch assembly must be It is necessary to use a coil wound with

It is also conventional to fill the switch with a ceramic compound such as epoxy resin. be. The jamming action may move the coil from its mount or otherwise may damage the coil.

One object of the invention is therefore to eliminate or reduce damage to coils during manufacture. The object of the present invention is to provide a manufacturing method that allows To this end, one aspect of the invention provides an inductive coil In a method of manufacturing a proximity switch having a circuit and an oscillation circuit: providing an end cap for receiving the coil; placing the coil in position within the end cap; filling the end cap at least partially with a hardenable ceramic compound; Ceramically hardening the coil in the end cap by; After that, connect the coil to the oscillation circuit and surround the oscillation circuit... installing the top unit; The manufacturing method includes:

Another problem is that changes in the coil and other circuit components are unavoidable; To give the switch uniform sensitivity, the detection circuit must therefore be adjusted during manufacturing. It is necessary to Until now, this has been done by using a regulating potential in the circuit. Such an adjustment It is time consuming, labor intensive, and the accuracy achieved is variable. Also for adjustment The use of potentiometers is desirable to reduce the size of the circuit using small or reduced size components. It is disadvantageous when

Therefore, the present invention provides an induction coil, an oscillator for driving the coil, and an induction coil for driving the coil. Sensing circuit with resistors adjusted during manufacturing to compensate for tolerances of other circuit components In a method of making a proximity switch comprising: a resistor as a resistive layer on a substrate; forming the resistor by polishing the layer until the desired sensitivity is obtained; the adjustment stage; Also provided is the method.

Another problem with known proximity switches is that electrical noise from the supply cables induced in and propagated along the metal housing of the switch, causing an inductive coil or to the point of interfering with other circuit components. To prevent or reduce this, Another aspect of the invention includes a metal housing; an end cap at one end of the housing; an induction coil placed within the end cap; an induction coil placed within the housing and connected to the coil; a circuit including at least one oscillator circuit; a housing including a cable entry; a metal closure member at the other end; further comprising a metal closure member at the other end; Coupled to the housing via a capacitor to suppress noise propagation through the housing , the proximity switch including a device connected to the housing next to the closure member; Ru.

One embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which: FIG.

FIG. 1 is a side sectional view of a proximity switch according to the invention: FIG. 2 is a partially sectional plan view of the switch portion of FIG. 1; FIG. 6 is an end view of the end cap of the switch in the direction ■ of FIG. 2; FIG. 4 is an enlarged plan view of the thick film substrate to which the switch circuit is attached; FIG. 5 is a diagram showing one stage during switch manufacture; FIG. 6 is a circuit diagram of the circuit of FIG. 4.

In particular, from FIG. It has a metal cylindrical housing 10 with external threads 12 for attachment. molded plastic A stick end cap 14 closes one end of the housing 10 and 16 is installed.

The switch circuit described below is mounted on a thick film printed circuit board 18 as shown in FIG. It includes micro-components not shown in FIG. The substrate 18 is molded in one piece. The stud 22 rests on the plastic pedestal 20 and is a one-piece molded column. 24 with adhesive. The other end of the housing 10 is connected to a cable strip. Metal cap 26 with a central opening into which the two-wire supply cable 28 along with the sleeve 30 enters. is closed by.

The assembly of the switch will now be described with particular reference to FIGS. 1 and 2. Ko The tile 16 is first placed into the end cap 14, secured in place, and then filled with epoxy. Ceramic hardening is performed using resin 32. Fittingly, products like 3M & 280 A low activity two-component resin is used and cured at 100°C. This is an extremely low initial viscosity. The resin penetrates around the coil and helps air bubbles escape.

For the same purpose, an end cap is used to pull the coil 16 away from the surface and allow the resin to penetrate. The inner surface of the cup 14 is provided with a rib or protrusion 34 (best seen in FIG. 3). It is.

This step damaged the coil with the coil and end cap remaining after curing This is advantageous in that it provides a monolithic circuit with no risk of movement.

By the way, the substrate 18 may be removed by conventional methods such as 70-soldering. It has the circuit components connected thereto and is then secured to the pedestal 20 as described above. cradle 20 includes an integral molding 736 that snaps into a cooperating hole in the end cap 14. There is. This is useful when manipulating the assembly and securing it to something such as a jig. A mechanical lock is provided between the pedestal and the end cap through a convenient hinge connection. Ko The ends of the wires are now attached to pads P6, P7 and P8 (FIG. 4) on board 18. Be soldered. Similarly, the wires 40 and 42 of the cable 28 are connected to pads P1 and It is soldered to P2 (Fig. 4).

The circuit is then modified to the specific coil and other component tolerances to obtain the desired sensitivity. needs to be adjusted to match. This means that the assembly is close to the standard target. This is achieved by fine-tuning the resistor Ri Q'c (Fig. 6) while energized by be done. According to an important feature of the invention, resistor R1,O is as shown in FIG. It is provided in the form of a resistive layer on the substrate and is finely tuned by the apparatus shown in FIG.

From FIG. 5, the assembly of base plate 18, pedestal 20 and end cap 14 is shown schematically at 46. above the work surface 48 at a given distance from the target 50. It is located in Cable 28 is connected to control unit 52. air polishing Unit 54 is activated to polish layer R10, while air polishing unit 54 is control unit by being placed on top of a motorized trolley (not shown). It moves in the direction shown in the figure under the control of the robot 52. The resistance of layer R10 becomes positive due to polishing. When increased to the correct value, the proximity switch circuit is activated and the resulting signal is suppressed. The control unit 52 is operated to demagnetize the polishing unit 54. Therefore, the resistance of the resistor The adjustment is automatic and self-correcting.

The polishing unit 54 has a diameter of 0.127 mm (0,005″) O,051mmc　O,002'　) Aluminum oxide in the air stream coming out of the dog nozzle Supply minium particles.

After fine adjustment of the resistive layer R10, the substrate and the components on it are covered with an elastic layer (not shown in the drawing). covered).

The layer may be, for example, Dow Corning 6 extruded onto the substrate in a layer approximately 3 nm thick. A soft silicone rubber such as No. 140 is preferred. This layer will be Ceramic hardening with poxy resin and microscopic parts with stress caused by curing of the same resin It works to remove the negative effects on the body.

The parts assembled so far can be glued together with a suitable adhesive such as the housing 10 and the end caps. The cap 14 is applied to the area around the cap 140 and the assembly is assembled so that the cap 14 is press-fitted onto the end of the housing. It is placed into the housing 10 until it is finished. Next, the switch is made of two-component transparent epoxy. The metal cap 26 is placed in place and the additional resin is then heated to 65°C. hardened with The cap 26 has rough internal threads 56 to provide a mechanical bond with the resin. I can do it. Additional resin is not shown in Figures 1 and 2 to clarify other parts. Not yet.

Various types of circuits suitable for use in switches are known in the art. 6th The circuit in the figure is illustrated as an example only and is not critical to the invention. Therefore, I will not explain it in detail. In short, it consists of the coil 16 and the light emitting diode ( 1, e, d,) D It is a 2-wire, C, circuit with all the components. Transistor T1 and T2 and the associated bias components constitute an oscillator that drives coil 16. to be accomplished. Transistors T3 and T4 output when a metal object loads coil 16. A snap-on level detector is provided which drives the power transistor T6 into conduction. Departure The regulated power supply for the vibrator and level detector is provided by Zener diode Z2 and Combined parts T5, R7% supplied by R8, TI, T8, and R9 Ru. To ensure that a constant voltage appears across Z2, the supply voltage and external negative It is essential to maintain a constant current flowing through 22 under various conditions of charge current. Ru. The current in Z2 is regulated by current regulators TI and T8. Any additional electricity The current is also bypassed from Z2 by T5.

Thus, when a metal object approaches the switch, T6 is connected to both ends of wires 40 and 42. conducts current through the device controlled by the switch directly or Drive via relay etc. le, d, D’l means the switch is “on” It will be lit. As seen in Figures 1 and 2, 1. θ, a, D2 are a pedestal 20 that is visible from the outside of the switch through an opening 11 in the housing 10; It is placed on a boss 21 having a monolithic structure.

Items p1-pB in FIG. 6 are connection pads on board 18. Items p1-pB in FIG.

Another important feature of the invention provides that the low voltage side of the circuit is connected via capacitor C4. and is connected to the housing 1o (FIGS. 4 and 60). Cable electrical noise is gold is induced at the entry point of the casing and propagates along the housing to cause coils 16 and 16. or other circuit components. remove or reduce this For this purpose, capacitor c4 is connected to the housing 10 adjacent to the cable inlet. . From FIG. 2, this connection is soldered to the board 18 on one end and taped on the other end. p doshi FIG, 5° international search report

Claims (1)

[Claims] 1. In the manufacturing method of a proximity swing f having an induction coil and an oscillation circuit, providing an end cap for receiving the coil; and storing the coil in place within the end cap. Steps: filling the end cap at least partially with a hardenable ceramic compound; Ceramically hardening the coil in the end cap by: installing an end cap unit on the winding hack song; The said manufacturing method including. 2. In the method described in claim 1, the ceramic compound is It is an epoxy resin comparand that is cured at high temperatures to facilitate degassing. The method characterized in that. 3. In the method according to claim 1 or 2, the inner end surface of the end cap is The above method, characterized in that the protrusion is provided at a distance from the coil. 4. In the method according to any one of the claims, the oscillation circuit and other The circuit is placed on the board, and the steps of placing the board on the pedestal and the pedestal and end cap are completed. creating a mechanical lock between the pool and the pool. Said method, characterized in that said mechanical lock also forms a hinged connection. 6. A method according to any one of the claims, further comprising an end cap. - Installation of the unit will later include filling the housing with additional ceramic comparands. The method characterized in that: Z with cylindrical housing: an end cap received at one end of the housing; a ceramic container placed within the end cap; With an induction coil fixed in it by a pound: having at least one oscillator circuit located within the housing and connected to the coil circuit and Proximity switch including. 8. A switch according to claim 7, comprising an additional charge for filling the housing. Said switch, characterized in that it contains a ceramic compound of addition. 9 In the switch according to claim 7 or 8, the circuit is made of a thick film substrate. The board is fixed to a plate-shaped pedestal, and the pedestal is attached to an end cap. The switch is hinged to the top. 10, with a metal housing: with an end cap at one end of the housing; placed in the cap; at least one induction coil placed within the housing and connected to the coil; oscillator circuit; metal closure for the other end of the housing, including the cable entry; A proximity switch that further suppresses noise propagation through the housing. In order to couple the low voltage side of the circuit to the housing via a capacitor, next to the closure member Said switch, characterized in that it includes a device connected to the contact point. 11. The switch according to claim 10, wherein the circuit and the capacitor the sensor is placed on a board placed within the housing, and the device is secured to the board. and a conductive adhesive tape captured between the housing and the closure member. The said switch. 12. Induction coil, oscillator that drives the coil, coil and other circuit components Proximity including a detection circuit with a resistor that is adjusted during manufacturing to compensate for tolerances. In how to make a switch: forming the resistor as a resistive layer on the substrate and until the desired sensitivity is obtained; , polishing the layer to tune the resistor; The method comprising: 13. The method according to claim 12, wherein the layer is blown out from a nozzle. said method, characterized in that said method is abrasive by means of air abrasive particles applied to said abrasive particles; 14. The method according to claim 13, wherein the switch is a standard metal The nozzle is maintained at a given distance from the target and connected to the control circuit, and the nozzle is automatically traversing the layers under the control of the control circuit until the switch is activated. Said method. 15. A proximity switch substantially as herein described with respect to the drawings. 16. A method of making a proximity switch substantially as herein described with reference to the drawings.