Simplified electric switch construction

A simplified electric switch construction is disclosed. The switch construction comprises at least a pair of confronting first and second terminals each having a bridge portion, a conductive resilient plate having one end shaped as a polygonal pyramid disposed in confronting relation to the bridge portion of the first terminal and an opposite end connected to the bridge portion of the second terminal, a presser for depressing an intermediate portion of the resilient plate to bring the tapered end into contact with the bridge portion of the first terminal, and a driver for depressing the presser. The switch construction may contain a printed-circuit board with an electric circuit thereon.

BACKGROUND OF THE INVENTION 
The present invention relates to a simplified electric switch construction 
including movable conductive contact members having a high contact 
pressure for making electric connection between terminals, and more 
particularly to such a switch construction which is simple in structure, 
stable in ON-OFF operation, small in size, and contains an electronic 
circuit. 
Various mechanisms have been devised for electric connection between 
terminals in switches. The known mechanisms have suffered from the problem 
of poor contact between contacts of movable conductive contact members and 
contacts of terminals (hereinafter referred to as "bridge portions"). FIG. 
1 of the accompanying drawings shows a conventional switch in which a 
terminal 1a has a bridge portion 2a to which a contact member 3 is fixed. 
A contact of the contact member 3 is brought into contact with a bridge 
portion 2b of a terminal 1b by depressing one end 4 of the contact member 
3. Since the contact 5 is pressed merely by a push against the bridge 
portion 2b through an area of contact, any dust or flux therebetween 
cannot be effectively removed. Any oxidized coating formed on the contact 
surfaces with time cannot be coped with, and it is necessary to plate the 
contact surfaces with precious metal which is chemically stable. According 
to another prior switch illustrated in FIG. 2, a contact member 7 normally 
urged downwardly by a spring 6 is moved to the right (as shown) to bring a 
contact 8b of the contact member 7 into contact with a bridge portion 10b 
of a terminal 9b while keeping a contact 8a of the contact member 7 in 
contact with a bridge portion 10a of a terminal 9a. This arrangement is 
better than the depression-type switch construction since the contact 8b 
is held in frictional contact with the bridge portion 10b. However, there 
is a structural limitation against imposing a sufficient contact pressure 
to remove any unwanted deposit sufficiently from the contact surfaces. 
There is known a DIP (dual in-line package) switch construction having an 
electronic circuit responsive to operation of a switch drive unit for 
selecting desired terminals to achieve a certain electric fuction. The DIP 
switch construction is composed of ordinary DIP switch terminals connected 
to portions of an electronic circuit on a printed-circuit board and 
accommodated in a casing. Its fabrication requires separate preparation of 
a DIP switch and a printed-circuit board having an electronic circuit 
provided thereon and normally molded in a mass of resin. Therefore, the 
conventional DIP switch construction is likely to be increased in size. It 
would be possible to form the DIP switch and the printed-circuit board as 
an integral structure. However, prior individual switches used as DIP 
switches would have a structural limitation against miniaturization, and 
would suffer from less contact stability due to a small current to pass 
through the switch. No good contact would be obtained if the conventional 
switch contact members were pressed against contacts printed on the 
printed-circuit board. To avoid this shortcoming, the contacts on the 
printed-circuit board and contact members would have to be plated with 
gold, and would be provided with greater surfaces of contact. 
SUMMARY OF THE INVENTION 
The above-described drawbacks in the prior art apparatus have been 
successively eliminated by the present invention. 
It is an object of the present invention to provide a simplified electric 
switch construction including movable conductive contact members having a 
high contact pressure for making electric connection between terminals. 
Another object of the present invention is to provide a switch construction 
which is simple in structure, stable in ON-OFF operation, small in size, 
and contains an electronic circuit. 
To achieve the above objects, a simplified electric switch construction 
according to the present invention comprises at least a pair of 
confronting first and second terminals each having a bridge portion, a 
conductive resilient plate having one end shaped as a polygonal pyramid in 
confronting relation to the bridge portion of the first terminal and an 
opposite end connected to the bridge portion of the second terminal, a 
presser for depressing an intermediate portion of the resilient plate to 
bring the tapered end into contact with the bridge portion of the first 
terminal, and a driver for depressing the presser. The switch construction 
may contain a printed-circuit board with an electric circuit thereon, the 
construction being small in size. 
These and other objects of the invention will become apparent from the 
following description of embodiments thereof when taken together with the 
drawings.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
A rotary switch according to an embodiment of the present invention for 
binary settings for an electronic circuit will be described with reference 
to FIGS. 3 and 4. 
The rotary switch comprises a casing 11 shown by the dotted lines in FIG. 3 
supporting four output terminals 12a through 12d and a single common input 
terminal 3 which are attached in place by insert molding. The input 
terminal 13 has a bridge portion 14 to which there is affixed as by fusing 
a contact body 15 in the form of a conductive, resilient metal plate. The 
contact body 15 has four movable contact members 16a through 16d extending 
from the portion thereof fixed to the bridge portion 14. The contact 
members 16a through 16d are bent at their proximal ends and urged 
upwardly, and have distal ends 17a through 7d punched out thicknesswise to 
form an acute angle 17e (FIG. 13(a)) and bent in the direction of the 
arrow X to direct a vertex P (FIG. 13(b)) shaped as a triangular pyramid 
(polygonal pyramid) in confronting relation to bridge portions 18a through 
18b, respectively, of the terminals 12a through 12d. When intermediate 
portions of the contact members 16a through 16d are depressed, the 
vertexes P shaped as triangular pyramids and acting as cutter blade edges 
of the contact ends 17a through 17d are brought into point-to-point 
contact with the bridge portions 18a through 18d to impose a high pressure 
contact on the order of 100 kg/mm.sup.2 on the bridge portions 18a through 
18b, respectively. At the same time, as shown in FIG. 11, each contact end 
formed as the cutter blade edge scratches the corresponding bridge portion 
from the solid-line position to the dotted-line position as the tapered 
contact end is depressed. Therefore, any flux, dust or dirt, and oxidized 
layer on the bridge portions 18a through 18d is removed or broken to 
thereby activate the contact surfaces. While in the illustrated embodiment 
the contact members 16a through 16d are connected to the common contact 
terminal 13 via the contact body 15, the contact body 15 may be dispensed 
with, and the contact members 16a through 16d may be fixed respectively to 
four independent input terminal bridge portions (not shown), so that four 
independent input-output circuits may be provided. 
The rotary switch also includes four pressers or steel balls 20a through 
20d held respectively in holes 22a through 22d in a holder plate 21 
disposed above the contact members 16a through 16d, the steel balls 20a 
through 20d serving to depress the vertexes P of the contact members 16a 
through 16d, respectively. The holder plate 21 is supported in the casing 
11 by a pair of ledges 23 mounted on an inner wall surface of the casing 
11 at dismetrically opposite corners thereof and also by a seat 24 (FIG. 
4) disposed between the contact members 16b, 16c on the bottom of the 
casing 11. The holder plate 21 is fixed in place by being pressed down to 
resiliently hold down the contact members 16a through 16d which are urged 
upwardly for thereby positioning the contact ends 17a through 17d in 
upwardly spaced relation to the bridge portions 18a through 18d 
respectively. The holes 22a through 22d in the holder plate 21 are 
positioned over intermediate portions of the contact members 16a through 
16d, respectively, and have a diameter larger than that of the steel balls 
20a through 20 d. Therefore, the steel balls 20a through 20d can move 
vertically in the holes 22a through 22d, respectively. The steel balls 20a 
through 20d are raised by the contact members 16a through 16d normally 
held against the lower surface of the holder plate 21 so that the steel 
balls 20a through 20d have portions exposed above the upper surface of the 
holder plate 21. When the steel balls 20a through 20d are depressed, they 
lower the contact members 16a through 16d, respectively, to cause the 
tapered contact ends 17a through 17d into abutting contact with the bridge 
portions 18a through 18d and then force the contact members 16a through 
16d to flex downwardly to enable the tapered contact ends 17a through 17d 
to scratch the bridge portions 18a through 18d, as illustrated in FIGS. 10 
and 11. Since the tapered contact ends 17a through 17d not only contact 
the bridge portions 18a through 18d but also scratch theem under a high 
contact pressure, any unwanted foreign matter such as dirt, dust, flux, 
and oxidized coating can easily be removed from the bridge portions 18a 
through 18d which are then activated for reliable and stable electric 
contact with the contact members 16a through 16d. 
While the contact members 16a through 16d are shown as being depressed by 
the steel balls 20a through 20d, the contact members 16a through 16d may 
be pressed downwardly by any other suitable bodies such as cylindrical 
bodies or rods with rounded heads provided they can be smoothly engaged by 
a driver (described later on) and depress the contact members 16a through 
16d until they flex downwardly. With such an alternative, the contact 
members 16a through 6d may have be of a substantially circular shape with 
a smooth projection. 
The steel balls 20a through 20d can selectively be depressed by a rotatable 
driver 25 (FIG. 3) having on its back cam lands 27 (FIG. 12) projecting 
from a surface 26 in positions of segments separated radially and 
circumferentially along four circular paths a through d according to 
numerical weighting of 2.sup.0 -2.sup.3. Since any steel ball 20 
positioned below the surface 26 is not depressed (FIG. 4), the 
corresponding contact member 16 disposed therebelow is not in contact with 
the output terminal bridge portion 18, and hence no electric output is 
produced from the output terminal 12. Any steel ball 20 positioned below 
one of the cam lands 27 is depressed, and hence the contact member 16 
below the depressed steel ball 20 is caused to contact the corresponding 
bridge portion 18 which is then electrically connected to the input 
terminal 13 to issue an electric output. By rotating the driver 25 
clockwise or counterclockwise in the direction of the arrow 28 (FIG. 4), 
the signal from the input terminal 13 is delivered selectively to the 
terminals 12a through 12d according to the angular displacement of the 
driver 25 (angularly oriented to one of numbers "0" through "9" inscribed 
on a cover 32 (FIG. 3). A numerical value can then be produced in 4-bit 
parallel binary notation from the output terminals 12a through 12d 
dependent on the contact combination. 
An O-ring 34 (FIG. 4) is mounted on a shoulder around a central shank of 
the driver 25. An indexing ring 30 has a pair of diametrically opposite 
ridges 31 placed in slots 29 in a corrugated surface of the driver 25. The 
cover 32 is placed over the casing 11 and fused thereto. The switch 
construction as thus assembled is shown in FIG. 4. 
While the rotary switch for binary settings have been shown and described, 
the present invention is in no way limited to such a switch construction. 
For example, the invention is applicable to a sliding switch having a 
slidable driver 35 as shown in FIG. 5a, a pushbutton switch having a 
pushbutton 36 with a pusher rod 37 as shown in FIG. 5b, or a pushbutton 
switch including a contact member 39 having a presser projection 38 as 
shown in FIG. 5c. 
With the switch of the foregoing embodiment, as described above, the 
movable contact members comprise conductive resilient plates having ends 
punched to form acute angles and bent into vertexes shaped as polygonal 
pyramids disposed in confronting relation to terminal bridge portions and 
opposite ends fixed to other terminal bridge portions. When intermediate 
portions of the contact members are depressed, the latter are moved down 
the cause the tapered contact ends thereof to contact the bridge portions 
under a high contact pressure and at the same time are caused to flex to 
enable the tapered contact ends to scratch the bridge portions, so that 
any flux, dirt, dust, and oxidized coating on the bridge portions can be 
removed or broken for activating the contact surfaces of the bridge 
portions. As a result, the switch construction of the invention is capable 
of stable and reliable switching operation, and can be used for passing or 
cutting off a small current. With this arrangement, there is no need for 
plating the contact surfaces with gold or silver, and the switch 
construction is simple in structure and hence quite inexpensive to 
manufacture. 
FIGS. 6 and 7 show a switch construction according to another embodiment in 
which an electronic circuit is incorporated therein. Like or identical 
parts in FIGS. 6 and 7 are denoted by like or identical reference 
characters in FIGS. 3 through 5, and will not be described in detail. 
As illustrated in FIGS. 6 and 7, output terminals 12a through 12d and a 
common input terminal 13 have vertically separated bridge portions 18a 
through 18d and 41a through 41d, and 14 and 42. These upper and lower 
bridge portions vertically sandwich a printed-circuit board 40 with an 
electronic circuit disposed on a lower surface thereof. The output 
terminals 12a through 12d and the common input terminal 13 are connected 
through the lower bridge portions 41a through 41d and 42 respectively to 
electronic-circuit portions of the printed-circuit board 40. The connected 
bridge portions and the printed-circuited board are molded integrally and 
housed in a casing 11. By thus integrally molding and placing the assembly 
in the casing 11, the switch construction can be greatly reduced in size. 
The upper bridge portions 18a through 18d and 14 are placed on an upper 
surface of the printed-circuit board 40. Although not shown, the 
printed-circuit board 40 itself has a number of terminals with joined lead 
wires extending outwardly of the casing 11. 
The electronic circuit on the printed-circuit board 40 may comprise a 
potentiometer as shown in FIG. 8a or a chip selector as shown in FIG. 8b. 
The potentiometer of FIG. 8a includes a common terminal COM which can be 
connected selectively to terminals a through d by bringing one of the 
contact members 16a through 16d into contact with a corresponding one of 
the bridge portions 18a through 18d of the output terminals 12a through 
12d. When the common terminal COM is thus connected to one of the 
terminals a through d, an applied voltage Vcc as divided a resistor R1, 
R2, or R3 is obtained from an output terminal OUT. The chip selector 
illustrated in FIG. 8b has a common terminal COM which can be connected 
selectively to terminals a through d in the same manner as that of the 
potentiometer of FIG. 8a. When the common terminal COM is coupled to one 
of the terminals a through d, one of output terminals a' through d' which 
corresponds to the one of the terminals a through d that has been 
connected to the common terminal COM is changed from the potential of a 
divided voltage Vcc applied to the ground potential. The chip selector can 
however meet a requirement to provide an output in a binary code. More 
specifically, the terminals a through d may be numerically weighted with 
2.sup.0 -2.sup.3, and a plurality of terminals may be switched in 
synchronism to obtain parallel binary codes from the output terminals a' 
through d'. 
Although in the arrangements of FIGS. 8a and 8b the components employed in 
the potentiometer and the chip selector are all resistors, capacitors, 
diodes, or logic elements may be used in place of the resistors. 
The casing 11 and the cover 32 may be molded of a thermosetting resin. 
However, the manufacturing control is awkward since the temperature at 
which the resin is set is high (280.degree. C. for example) and it takes a 
long time for the resin to set. Where the parts are molded of a 
thermoplastic resin, the manufacturing control is easy and the cost is low 
because the molding temperature is relatively low (170.degree. through 
260.degree. C. for example) and the molding process takes a short period 
of time. While the casing 11 and the cover 32 of thermoplastic resin are 
thermally deformable and softenable, they are reinforced by the 
printed-circuit board 40 which is made of ceramics, glass, or epoxy resin 
for increased mechanism or physical dimensional stability and strength. 
Where the casing 11 and the cover 32 shown in FIGS. 3 through 5 are made 
of a thermoplastic resin, a reinforcing board (with no electronic circuit) 
may be placed in the position of the printed-circuit board shown in FIGS. 
6 and 7 to strengthen the components for increased mechanical or physical 
dimensional stability and strength against thermal deformation. 
While the rotary switch for binary settings have been shown and described 
with respect to FIGS. 6 and 7, the present invention is in no way limited 
to such a switch construction. For example, the invention is applicable to 
a sliding switch having a slidable driver 35 as shown in FIG. 9a, a 
pushbutton switch having a pushbutton 36 with a pusher rod 37 as shown in 
FIG. 9b, or a pushbutton switch including a contact member 39 having a 
presser projection 38 as shown in FIG. 9c. In each of these alternatives, 
the printed-circuit board 40 is disposed in the switch casing. 
With the switch construction having an electronic circuit contained 
therein, as described above, a printed-circuit board with an electronic 
circuit thereon and a separate DIP switch are not employed, but a DIP 
switch and a printed-circuit board with an electronic circuit thereon are 
intergrally put together with the printed-circuit board sandwiched between 
upper and lower terminal bridge portions and disposed in the casing. 
Therefore, the switch construction is quite small in size. In addition, 
the movable contact members comprise conductive resilient plates having 
ends punched to form acute angles and bent into vertexes shaped as 
triangular pyramids disposed in confronting relation to terminal bridge 
portions and opposite ends fixed to other terminal bridge portions. When 
intermediate portions of the contact members are depressed, the latter are 
moved down the cause the tapered contact ends thereof to contact the 
bridge portions under a high contact pressure and at the same time are 
caused to flex to enable the tapered contact ends to scratch the bridge 
portions, so that any flux, dirt, dust, and oxidized coating on the bridge 
portions can be removed or broken for activating the contact surfaces of 
the bridge portions. As a result, the switch construction of the invention 
is capable of stable and reliable switching operation, and can be used for 
passing or cutting off a small current. With this arrangement, there is no 
need for plating the contact surfaces with gold or silver, and the switch 
construction is simple in structure and hence quite inexpensive to 
manufacture. 
Thus, there is provided in accordance with the invention a simplified 
electric switch structure which has the advantage discussed above. The 
embodiments described are intended to be merely excemplary and those 
skilled in the art will be able to make variations and modifications in 
them without departing from the spirit and scope of the inventions. All 
such modifications and variations are contemplated as falling within the 
scope of the claims.