JPS5947411B2 - pushbutton switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pushbutton switch or a keyboard switch used in electronic devices such as electronic desktop calculators and touch-type electronic tuners.

Conventionally, in order to make electronic desktop calculators thinner and more compact, various types of pushbuttons have been used in which movable contacts made of sheet-like contact metal or elastic conductors such as conductive plastic are pressed by pushbuttons made of insulators, etc. A key switch has been developed. There is also a type in which a protruding key part is provided on the upper part of the movable conductive rubber contact and an insulating coating is provided on the protruding key part. As an example, U.S. Patent No. 3,699,294 is shown in Section 6. Here, A indicates the assembled product, and 口 indicates its parts. In the figure, reference numeral 1 denotes a frit circuit board, on the upper surface of which a fixed contact 2 and its circuit pattern are provided, and a terminal 9 for connection to the above is fixed on the lower side. A smoothing board 3 made of an insulating plate placed on the upper side of the printed circuit board 1 is provided with a window corresponding to the fixed contact 2. Reference numeral 4 denotes a movable elastic conductive contact plate made of a mixture of silicone rubber and carbon powder, which is provided with a movable contact portion 5 corresponding to the fixed contact 2 as a lower protrusion, the upper part of which is provided with a push-button protrusion 6, and its surface is insulated. It is coated.

A cover plate 7 also serves as a display plate, and is provided with a window 8 that fits into the pushbutton projection 6.

Then, the circuit board 1, the spacer 3, the movable elastic conductive contact plate 4, and the cover plate 7 are mutually positioned, overlapped, and fixed to form a keyboard switch. In this switch, the movable elastic conductive contact plate 4 made of conductive rubber is made of a mixture of carbon or precious metal powder and rubber-based resin, etc., to reduce flammability and elastic modulus and improve compressibility. This is because contact conductivity is obtained only when the contact pressure exceeds a certain level, and because the conductivity increases with increasing pressure, and because the sponge-like structure is used inside to increase the effective contact area and reduce contact resistance. Conductive rubber contacts with microscopic cavities are used. In addition, it is desirable for the push button to have the feel of a snap switch operation, so a hemispherical thin elastic part is provided on the switch operation part or the movable contact part, and the push button is made of plastic such as mylar or polycarbonate, or silicone rubber, which has excellent stress characteristics, to give the feel of a snap switch. Keyboard switches and the like have also been developed. For example, US Patent Nos. 3,717,737 and 387,958
6 etc., and in Japan, Utility Model Application Publication No. 49-37765,
U.S. Publication No. 51-8703, Japanese Patent Publication No. 52-71658 and 5
There are inventions or ideas such as No. 2-67775. In order to simplify parts production and assembly and reduce costs, the present invention provides a keyboard switch in which the push button knobs are made individual and can be easily inserted into the board, and the number and arrangement of push buttons can be easily changed. The purpose is to obtain. The present invention, for example, allows six switch units to be arranged in series.
They form a pair of key switches. Then, here, by overlapping each of the switch parts, which are made up of 6 pieces excluding the knob, it is possible to easily assemble 6 pieces of switch units into one unit, and also, these 6 piece 1 set of key switches can be assembled in parallel or It is also possible to arbitrarily increase the number of unit switches by arranging them in series. Although the details will be described later, since the push button knobs 30 that drive the switches are independent of each other and are mounted individually, the number of push button knobs 30 to be mounted on a set of six switch units can be reduced arbitrarily. It's easy. Embodiments of the present invention will be described in detail below with reference to the drawings.

1 to 5 are drawings showing an embodiment of the present invention, in which FIG. 1A is an assembled perspective view with a part cut away, the same opening is a front view of the same mounted on a panel board, FIG. 2A, Both openings are a plan view of the embodiment of the main body board, Figure C and 2 are enlarged cross-sectional explanatory views of the fixed contact pattern of the main body board, and Figure 3 is a movable contact plate, and A is a plan view, mouth is a side view, and C is a FIG. 4 is a partially cutaway perspective view of the press button, and FIG. 5 is a perspective view of the electrode terminal.

As shown in FIG. 2, the main substrate 10 (hereinafter simply referred to as the substrate) is a rectangular heat-resistant insulating substrate such as a Bakelite laminate, with fixed contact patterns 11, 12, 12/, on one side thereof.
etc. are provided on the surface of each switch unit corresponding to the switch design.

Also, six switch units are connected in series here. Here, as an example, in FIG. 2A, a common electrode pattern 12 is shown in which two individual individual conductive electrode patterns 11 are connected. Also, in the opening of Figure 2, the electrode pattern with one side serving as a common electrode is shown as 12/. Then, a pair of mutually insulated fixed contact portions 15 are placed opposite to each other with a certain narrow interval 15a in between, corresponding to the short-circuiting carbon rubber elastic movable contacts 25 provided on the movable contact plate 20, which will be described in detail later. There are 6 sets in total. Terminal holes 13 are provided at equal intervals corresponding to fixed contact patterns 11, 12, 12/, etc., and eyelet fixing portions 43 of external terminals 40, which will be described later, are inserted into the terminal holes 13 and crimped.
Conductive connections stick.

However, due to the circumstances of the set circuit, the terminal holes 13 are rarely all used as terminal holes. In this embodiment, the details will be described later, but as an example, the lower fixed surface of the movable contact plate 20 having elasticity that is fixed to the substrate 10 is provided in a staggered manner for positioning, or is connected to the caulking protrusion 23. It plays the role of a positioning hole. Here, the positioning hole that engages with the positioning protrusion of the movable contact plate 20 may be provided separately from the terminal 13. Here, terminal positioning grooves 14 that engage with positioning protrusions 44 of terminals 40 made of metal plates, which will be described later, are provided on both sides of the board 10, and snap-in positioning engagements that engage with snap-in mounting legs 36 of push buttons 30, which will be described in detail later. Groove 16 and movable contact plates 2 at both ends in the longitudinal direction
A pair of positioning grooves 17 that engage with the protrusions 27 at both ends of the holder 1 are respectively provided. The fixed contact patterns 11, 12, 12' of the substrate 10 shown in FIG.
A pair of fixed contact portions 15 and a terminal electrode portion 13 around the terminal hole that makes electrical contact with the external terminal 40 fixed through the terminal hole 13
a and a conductive connection portion 13b therebetween. Here, the switch fixed contact patterns are generally required to have low resistance and contact resistance, high reliability of electrical connection, and sufficiently high insulation between the contact patterns. FIG. 3 shows the movable contact plate 20.
The movable contact plate 20 made of a single continuous piece of elastic rubber has individual base parts 26 that are in close contact with each switch part of the board 10 and open downward to form a space 22a corresponding to the fixed contact part 15 of the board 10. However, there is a dome-shaped elastic skirt portion 22 on the upper side of the base portion 26 that continuously performs the snub button push operation.
At the upper end of the elastic skirt portion 22 is a platform-like protrusion 21 .
A downward contact protrusion 24 is provided on the inside of the table-like protrusion 21, and a carbon rubber elastic contact 25 is fixed to the lower tip of the contact protrusion 24 for making switch contact by coming into contact with and separating from the fixed contact 15 of the board. . The movable contact plate 20 also has a somewhat thin burnable connection part 28 connecting between the base parts 26, and has relief grooves 28/ on the bottom part thereof on both sides thereof to engage with the head part 41 of the external terminal 40. We have one pair each. Further, here, two positioning protrusions 23 projecting downward are provided on the central switch unit portion to engage with the terminal holes 13 of the board 10. The positioning protrusion 23 may be long enough to be fixed to the substrate 10 by thermocompression bonding or ultrasonic pressure welding, or a snap-in hook may be attached to its tip. Also, a pair of lower protrusions 2 are provided at both ends in the longitudinal direction to engage with the grooves 17 of the substrate 10.
7 is provided. FIG. 4 shows a mouth-shaped pushbutton 30 made of insulating and elastic plastic, the operating knob 31 at the upper end engages with a hole in the cabinet of the set and projects outward to form an operating section, and the shoulder 32 Continuing thereon, a flat main body portion 33 is provided.

A pair of elastic plate-shaped mounting legs 36 for fixing a snap-on pin are suspended from the lower portions of both sides of the main body portion 33 and have a mouth shape that engages with a pair of engagement grooves 16 on both sides of the base plate 10. There is. Each mounting leg 36 has a vertical slit 38 at its lower center end, and a pair of supporting legs 36a at the bottom of the mounting leg 36 has protruding claws 37 for locking and fixing provided on the outer side of each lower end. At the lower end of each mounting leg 36, a tapered part 37b for insertion is provided inside, including a protruding claw part 37. This then engages with the side step portions of the pair of side positioning engagement grooves 16 of each switch unit on the board 10, and
The snap-in locking is achieved by the elasticity of the pair of mounting legs 36.
At this time, the lower surface of the recess 34 on the lower side of the push-button main body 33 presses the platform-like protrusion 21 of the movable contact plate 20 downward to some extent and comes into contact with it. The pushbutton 30 has its operating knob 3
1 is pushed down, the elastic skirt portion 22 of the movable contact plate 20 is bent downward via the trapezoidal protrusion 21, thereby performing a snap operation. The elastic movable contact 25 made of carbon-based conductive rubber has a concentric double-row ring-shaped elastic contact line 25 and 25 ports on the bottom surface of the substrate 1.
Electrical connection is made by making bridge contact with the pair of fixed contact portions 15 of No. 0 on a wide surface. FIG. 5 shows an external terminal 40 made of a metal plate that engages with the terminal holes 13 of the conductive fixed electrode patterns 11, 12, 12/ of the substrate 10. The terminal 40 is connected to the contact plate portion 41. Engagement positioning protrusion 4 that engages with groove 14 of substrate 10
4. An external terminal 42 and a tip terminal portion 45 with a narrow width are provided through the shoulder portion of the external terminal 42, and the tip terminal portion 45 has an elastic bend 46 for inserting a snap pin that is fixed to a terminal hole in which the printed board is engaged. It is set up. In the present invention, a relatively thin high-resistance carbon resin resistor vein with a high resin content of about 3 μm is first applied to the base layer A on the insulating substrate as a pair of fixed contact conductive layer patterns 11, 12, and 1γ on the surface of the insulating substrate 10. Apply as. This underlayer A increases the adhesive strength with the substrate, and also prevents insulation deterioration and other failures due to well-known silver migration when a silver resin conductive layer B is provided as an intermediate layer to be described below. Next, a silver resin conductor layer B is applied on the base layer A as a conductive intermediate layer. As an exception, the silver resin conductor layer B may be omitted if the contact resistance between the contacts is high (approximately KΩ), but if the contact resistance between the contacts is required to be low (approximately 50-Ω), it may be omitted. ) is provided with a silver resin conductor layer B including the contact portion 15. In the case between the above two (approximately 500Ω), the B layer is provided only in the conductive connection portion 13b excluding the contact portion. Here, the terminal electrode part 13a
Since there is a dimensional margin, the silver resin conductor layer B is exposed. The thickness of the silver layer can also be easily made thinner (eg, about 10 μm). Next, a low resistance carbon resin is applied as the top layer C on the fixed contact portion 15 except for the gap 15a between the fixed contacts. Although the contact resistance here is somewhat higher than that of gold contacts, etc., it has the same level of reliability as the highest grade contacts such as gold. In other words, copper contacts oxidize in the air, increasing their contact resistance, and cannot be used as contacts unless the surface is coated with gold or silver. It is well known that the contact resistance of commonly used silver contacts increases in sulfide gas, and that silver contacts are susceptible to breakdowns such as insulation deterioration due to migration and the like in high humidity environments. Here, if the uppermost layer C is coated on the conductive connection part 13b, excluding the terminal electrode part 13a for convenience of the process, troubles due to silver migration and sulfurization in this part can be reduced. Moreover, the fixed electrode patterns 11, .
12 and 12/ are coated with a carbon resin layer A, a silver resin layer B, and a low resistance carbon resin layer C in a desired pattern, including the fixed contact part 15, the terminal electrode part 13a, and the conductive connection part 13b, Since heat treatment baking is performed, the process is simple, the adhesive strength of the coating film is strong, and the cost is low. Here, the conventional printed circuit copper foil etching nog pattern fixed electrode,
If platinum-based or gold plating is used, problems caused by insulation deterioration due to migration and the formation of an insulating film on the contact surface such as sulfurization, which are problems with silver plating, will be reduced, but the cost will be high. In the case of gold-based materials, there is mutual diffusion, etc., and in order to improve reliability, a considerable amount of man-hours such as thickening and multilayering are required, which increases costs. Further, for the main body substrate, etc., it is necessary to use expensive special products such as an epoxy board containing glass fiber to prevent silver migration at the silver contacts.

Since the present invention does not have the above-mentioned drawbacks, it is possible to use a Bakelite laminate that is inexpensive and has excellent properties, although its silver migration properties are inferior. Here, the fixed contact pattern contacts the movable contact 25 and is insulated from each other? Accurately providing the narrow gap 15a between the pair of contact portions 15 is a difficult technique when performing frit work such as carbon resin conductive veining, which requires a somewhat thick film thickness.

In another embodiment of the present invention, a slit or a sufficiently deep recess 15a' is provided in advance in the gap 15a between the connectors, so that the conductive veint in this area does not adhere during the conductive printing process such as the screen method, so that the conductive veins can be easily and accurately connected to each other. The desired insulated fixed contact pattern 15 is obtained. This also becomes more advantageous as the contact pattern becomes multilayered and thicker. In the present invention configured as described above, the engaging portions for attaching the pushbutton are the engaging grooves (recesses) 16 on both sides of the substrate, and the structure is small and simple, and can be manufactured by panoching. Therefore, processing is easy and the cost is low.

Furthermore, when mounting the pushbutton 30 and the board 10, the pushbutton's pair of elastic mounting legs 36 are opened outward, and the mounting legs are inserted into the pair of grooves 16 on the side of the board that engage with the mounting legs 36. 36
It is easy to insert without any effort. Also, the mounting leg 36
Since the protruding claw portion 37 for locking and fixing is provided in the outward direction, the structure of the molding die is simple and molding is easy. In addition, the pushbutton knobs are individual and can be easily inserted into the board, so by changing the number and arrangement of the pushbuttons inserted, it is easy to use (switch) a keypad switch with multiple switch units. can be changed to .

[Brief explanation of drawings]

1 to 5 are drawings showing an embodiment of the present invention, in which FIG. 1A is an assembled perspective view with a part cut away, the same opening is a front view of the same mounted on a panel board, FIG. 2A, Both openings are a plan view of the embodiment of the main body board, Figure C and 2 are enlarged cross-sectional explanatory views of the fixed contact pattern of the main body board, and Figure 3 is a movable contact plate, and A is a plan view, mouth is a side view, and C is a FIG. 4 is a partially cutaway perspective view of the pushbutton, and FIG. 5 is a perspective view of the electrode terminal. FIG. 6 shows a conventional example of a push-button switch using elastic plastic movable contacts. 10... Main board, 1
L12, 124...Fixed contact pattern, 13...
...Terminal hole, 15...Fixed contact part, 15a
...Gap between one set of fixed contacts, 20...
...Movable contact plate, 22...Elastic skirt part,
25... Carpon rubber elastic movable contact, 30.
...Push button, 31...Operation knob,
36...Mounting leg, 36a...Support leg part, 37b...Insertion taper part, 38...
・Slit, 40...external terminal.

Claims (1)

[Claims] 1. A plurality of pairs of fixed contacts 15, 15 facing each other with a narrow insulating gap 15a provided in the middle are provided in parallel in the longitudinal direction on the surface of a rectangular main body substrate 10 made of an insulating material. Board 1
0, a plurality of carbon rubber elastic movable contacts 25 that simultaneously contact the fixed contacts 15, 15 are fixed to each switch unit, and each switch unit is made of a push-button engaging protrusion, an elastic skirt, and a push-button. A movable contact plate 20 with an independent elastic snap action part is attached to the substrate 1.
In the push-button switch fixed to 0, each individual push-button 30 is made of elastic plastic, and the upper part of the flat main body 33 is provided with an operating knob 31 that serves as an operating section.
A pair of elastic plate-shaped mounting legs in a Π shape that engage with a pair of engagement grooves 16 provided on both sides of the flat main body substrate 10 are provided at the lower portions of both sides of the main body portion 33. 36 hanging down, and a protruding claw portion 37 for locking is provided on the outer side of the lower end of each mounting leg, and the movable contact plate 20 is formed from one continuous plate of elastic rubber, and the movable contact plate 20 is made of a continuous piece of elastic rubber. An individual base portion 26 that is in close contact with a switch portion consisting of a pair of fixed contacts 15, 15 on the board 10, a space portion 22a corresponding to the fixed contact portion 15 on the main body board 10, and a dome-shaped elastic skirt portion connected to the base portion 26. 22 and a table-like protrusion 21 that continues to the upper end of the elastic skirt part 22 are provided, and the tip of a downward contact protrusion 24 provided at the inner bottom of the table-like protrusion 21 is connected to and separated from the fixed contact 15 of the main body board. This is a push-button switch in which a carbon rubber contact 25 is fixed, and a lower recess 34 of a main body 33 of a push-button 30 is forcefully brought into contact with a platform-like protrusion 21 of the movable contact plate 20. 2. The pushbutton switch according to claim 1, wherein an insertion tapered portion 37b is provided inside the lower end of the pair of elastic mounting legs 36 of the pushbutton 30.