Digital switch assembly

A digital switch assembly which comprises a casing having a plurality of output terminals, a rotor rotatably accommodated within the casing and adapted to be rotated either directly or indirectly by the application of a finger pressure thereto, feelers carried by and positioned inside the casing and electrically connected to the respective output terminals; a circuit board carried by the rotor and having a predetermined pattern of electric circuits adapted to be selectively engaged with the feelers to complete a desired circuit configuration depending on the position of the rotor, a grounding terminal member carried by the casing, and a circuit element extending substantially between the location at which the finger pressure is applied to rotate the rotor and the grounding terminal member for establishing a discharge circuit through which an electrostatic charge set up in the body of the operator can be grounded.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
This invention generally relates to a switch assembly and, more 
particularly, to a digital switch assembly suited for use as an input 
device for inputting numerical information such as, for example, 
temperature, time or count, to an electronic instrument, for example, a 
timer, a counter or a measuring device. 
2. Description of the Prior Art 
A digital input device currently widely used in, for example, a measuring 
instrument, comprises, as shown in FIG. 1 of the accompanying drawings, a 
digital switch unit 2 comprised of a plurality of switch assemblies 1 
connected together in side-by-side relation to each other, which is in 
turn mounted on a common instrument panel 4 of, for example, a timer 
device 3. Each of the switch assemblies 1 forming the digital switch unit 
2 has a pair of operating members 1a adapted to be manipulated by an 
operator one at a time to establish a particular electric circuit 
associated with a digital data to be inputed. 
Where each of the switch assemblies SW is manufactured in a miniature size 
as it is a recent trend in the art, it has been found that, when one of 
the operating members in each switch assembly is depressed by the 
application of an external finger pressure, the finger of the operator is 
brought in the close vicinity of an internal circuit element, for example, 
a printed circuit board having a pattern of conductors formed thereon, 
which is located inside the switch assembly. By way of example, the finger 
tip of the operator depressing the operating member comes to a position 
spaced a distance of about 2 to 3 mm from the printed circuit board. Once 
the finger tip is brought to such a position, discharge of an 
electrostatic charge set up in the body of the operator takes place 
between the finger tip and a portion of the printed circuit board closest 
thereto, generating a high voltage which would adversely affect the 
circuit arrangement to such an extent as to result in erroneous operation 
of the circuit arrangement and/or damages to electronic component parts 
employed in the circuit arrangement. 
SUMMARY OF THE INVENTION 
Accordingly, this invention has been developed with a view to substantially 
eliminating the above described disadvantages inherent in the prior art 
switch assembly and has for its essential object to provide an improved 
switch assembly which is compact in size and substantially free from such 
damages as may be brought by the discharge of the electrostatic charge set 
up in the body of the operator.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
Before the description of the preferred embodiments of this invention 
proceeds, it is to be noted that like parts are designated by like 
reference numerals throughout the accompanying drawings. 
Referring first to FIGS. 1 and 2 and in accordance with a first preferred 
embodiment of this invention, a digital switch assembly comprises a casing 
constituted by a base 10 of a generally container-like configuration and a 
cover plate 18. The base 10 includes a top operating panel 10a having a 
window 11 and a pair of openings 12 defined therein, said openings 12 
positioned on respective lateral sides of the window 11. For the purpose 
of anti-dust protection, the window 11 is covered by a transparent plate 
14. The base 10 also includes a pair of side panels having respective 
engagement pawls 15 formed integrally therewith and protruding rearwardly 
of the base in a direction opposite to the cover plate 18 and also having 
respective engagement recesses 16 defined therein in alignment with the 
engagement pawls 15. The base 10 further includes a bottom panel carrying 
a pair of spaced grounding terminals 17 pressure-fitted thereto, or 
otherwise insert-molded thereinto, and extending downwardly outwardly 
therefrom for external electrical connection to the ground potential, each 
of said grounding terminals 27 having its opposite ends 17a and 17b 
situated inside and outside the base 10. 
The cover plate 18 carries a plurality of output terminals 19 embedded 
therein during the manufacture thereof by the use of a plastics 
insert-molding technique and have respective feelers 19a formed integrally 
therewith. This cover plate 18 has a central opening 20 which is in turn 
closed by a sheet member 21. 
A rotor 22 is accommodated within the casing and is rotatably mounted on a 
shaft 13 formed integrally with the base 10 and protruding therefrom in a 
direction towards the cover plate 18. The rotor 22 has its outer 
peripheral surface printed with, or otherwise embossed with, a series of 
numerical figures 0 to 9. The rotor 22 has one end face carrying a printed 
circuit board 23 having a predetermined pattern of conductors (not shown) 
and the opposite end face formed integrally with a sprocket gear 24 in 
alignment with th axis of rotation of said rotor 22. It is the conductors 
printed on the circuit board 23 to which the feelers 29a integral with 
the output terminals 19 contact slidingly, and accordingly, as the rotor 
22 rotates about the shaft 13, the feelers 29a can complete a plurality of 
electric circuits one at a time. 
The casing also accommodates a pair of spaced operating members 25 
protruding at one end to the outside of the casing through the respective 
openings 12. Each of the operating members 25 is made of electroconductive 
plastics or, alternatively, it may have an electroconductive film applied 
over the entire surface thereof or only a portion thereof that extends 
from a contact area accessible to a finger of an operator of the switch 
assembly down to the opposite contact area 25a. In the case of the 
electroconductive film, it may be deposited by the use of any known metal 
vaporization process or a sputtering process. It is to be noted that, 
although the operating members 25 may be made of metal, plastics is 
preferred as a material for the operating members 25 because the latter 
can be imparted with elasticity. The operating members 25 are normally 
biased upwards as viewed in FIG. 3 by a wire spring 27 having its opposite 
ends engaged to the contact areas 25a of the respective operating members 
25 as best shown in FIG. 3 and are adapted to be moved downwards one at a 
time against the wire spring 27, when an external push or finger pressure 
is applied thereto, to stepwisely rotate the rotor 22 by the engagement of 
a respective projection 26 integral therewith with the sprocket wheel 24. 
In practice, the digital switch assembly of the construction described 
hereinabove is used in plural number to provide a switch unit. In other 
words, in a certain application, the switch assemblies each being of the 
construction described above are connected together in side-by-side 
relation to each other with the engagement projections 15 of one switch 
assembly being elastically engaged in the engagement recesses 16 of the 
next adjacent switch assembly. The switch unit so fabricated is in turn 
mounted on a console panel for, for example, a timer and, in such case, 
the output terminals 19 are electrically connected to an electric circuit 
arrangement in the timer and the grounding terminals 17 are connected to 
the ground potential. 
While the switch assembly according to this invention is constructed as 
hereinbefore described, and when one of the operating members 25 is 
depressed by the application of the external push as shown in FIG. 3, the 
projection 26 integral therewith pushes one tooth of the ratchet gear 24 
to rotate the rotor 22 stepwisely through an angular distance 
corresponding to the pitch between the adjacent two teeth of the ratchet 
gear 24 in one direction. The rotation of the rotor 22 in the opposite 
direction can be similarly effected by depressing the other of the 
operating members 25. In either case, the switch assembly according to 
this invention is so designed that the minimum distance established 
between the operation of member 2 and the printed circuit board 23 when 
the operating member 25 has been depressed, which distance is indicated by 
D1, can become greater than the distance D2 between the corresponding 
contact area 25a of the operating member 25 being depressed and the 
adjacent grounding terminal 17. Accordingly, when either of the operating 
members 25 is depressed, an electrostatic charge set up in the body of the 
operator of the switch assembly can advantageously be discharged between 
the respective operating member 25 and the adjacent grounding terminal 17 
and then to the ground then through the adjacent grounding terminal 17 
and, therefore, any high voltage which would be generated upon the 
discharge of the electrostatic charge will not be applied to an electronic 
circuit arrangement in a subsequent stage, thereby minimizing or 
substantially avoiding any possible erroneous operation of the switch 
assembly and/or any possible damages to electronic component parts. 
It is to be noted that, while in the construction described hereinabove, a 
space has been described as established between the contact area 25a of 
each of the operating members 25 and the associated grounding terminal 17 
as shown by the distance D2 when the respective operating member 25 has 
been depressed, it may be possible to render the contact area 25a of the 
respective operating member 25 to contact the associated grounding 
terminal 17 when the respective operating member 25 has been depressed. 
In the foregoing embodiment described with reference to and shown in FIGS. 
2 and 3, since the grounding terminals 17 are carried by the bottom panel 
of the base 10 with their surfaces oriented at right angles to that of 
each of the output terminals 19. This arrangement is advantageous in that, 
when the switch assembly of this invention is mounted on the console panel 
with the terminals 17 and 19 plugged into associated sockets provided on 
the side of the console panel, the switch assembly of this invention can 
steadily be supported. This is particularly true where only one switch 
assembly is utilized. 
In addition, in the foregoing embodiment, the grounding terminals 17 have 
been described as fixed in the base 10. However, as shown in FIG. 4, they 
may be fixed in the cover plate 18. In this case, the grounding terminals 
17 can be prepared from a single sheet of electroconductive material 
together with the output terminals 19 by the use of any known press work, 
for example, a metal blanking process, followed by the insertion of the 
terminals 17 and 19 in the cover plate 18 during the manufacture of the 
cover plate 18 by the use of any suitable plastics molding technique. 
According to this modification shown in FIG. 4, the number of separate 
component parts necessary to fabricate the switch assembly can 
advantageously be minimized and the switch assembly can be economically 
manufactured, because the formation of the terminal 17 and 19 can be done 
simultaneously. 
Referring now to FIGS. 5 and 6, the wire spring 27 employed in the 
foregoing embodiment described with reference to and shown in FIGS. 2 and 
3 is replaced with separate wire springs 28 and 29 one for each operating 
member 25. These wire springs 28 and 29 concurrently serve as grounding 
terminal members and, accordingly, in the second preferred embodiment 
shown in FIGS. 5 and 6, these grounding terminals 17 employed in the 
foregoing embodiment are eliminated. 
As best shown in FIG. 5, the wire spring 28 is exteriorly inserted in a 
bearing recess 30 defined in the bottom panel of the base 10 with its 
opposite ends 28a and 28b located inside and outside the base 10. 
Similarly, the wire spring 29 is exteriorly inserted in the bearing recess 
30 with its opposite ends 29a and 29b located inside and outside the base 
10. These wire springs 28 and 29 are so mounted that the respective ends 
28a and 29b of the wire springs 28 and 29 can be held in position 
constantly engaged to the contact areas 25a of the corresponding operating 
members 25. Therefore, it will readily be seen that the operating members 
25 are not only normally biased upwardly by the associated wire springs 28 
and 29, but also grounded to the ground potential through the associated 
wire springs 28 and 29. 
It is to be noted that the bearing recess 30 need not be always necessary. 
Instead of the employment of the bearing recess 30, the wire springs 28 
and 29 may be held in position as inserted through the bottom panel of the 
base 10. This can readily be accomplished by the use of any known plastics 
insert-molding technique. 
The digital switch assembly according to the second preferred embodiment is 
advantageous in that, since the wire springs 28 and 29 serve not only as 
biasing elements for upwardly biasing the operating members 25, but also 
as grounding terminals to be connected to the ground potential, the number 
of component parts forming the switch assembly can be minimized with the 
structure of the switch assembly consequently simplified. 
According to a third preferred embodiment shown in FIGS. 7 to 9, the side 
panels of the base 10 have respective through-holes 31 defined therein for 
receiving grounding terminals 32. The grounding terminals 32 have one end 
32a extending into the base 10 through the through-holes 31 and the 
opposite end extending along the associated side panels and terminating 
exteriorly of the base 10 so as to extend in parallel relation to the 
output terminals 19 carried by the cover plate 18 (See FIG. 2). 
One end portion of each of the operating members 25 made of 
non-electroconductive material, which is accessible to the finger of the 
operator, has a bearing hole 34 defined therein and accommodating therein 
a respective electroconductive Tee-piece 35 pressure-fitted thereinto. The 
Tee-pieces 35 in the respective bearing holes 34 defined in the associated 
operating members 25 have their exterior surfaces provided with any 
suitable indicia representative of the direction of rotation of the rotor 
22 inside the casing, for example + (plus) sign and - (minus) sign as 
shown. 
In this third embodiment of this invention shown in FIGS. 7 to 8, care if 
required so as to position the ends 32a of the grounding terminals 32 at a 
location spaced a minimum distance D2 from the tip of the respective 
electroconductive Tee-piece 35, which distance D2 should be smaller than 
the minimum distance D1 between the printed circuit board 23 and the end 
of the Tee-piece 35 in the respective operating member 25 as shown. With 
this design, it is possible to let the electrostatic charge built up in 
the body of the operator be discharged to the ground potential through any 
one of the Tee-pieces 35 and then through the grounding terminals 32 and, 
therefore, similar advantages as hereinbefore described in connection with 
the first preferred embodiment can equally be appreciated. 
In describing any one of the foregoing embodiments of this invention, the 
cover plate 18 and the rotor 22 have been described as carrying the 
feelers 19a and the printed circuit board 23, respectively. However, the 
feelers 19a and the printed circuit board 23 may be provided on the rotor 
22 and the cover plate 18 if desired. 
In any one of the first and third embodiments of this invention, the 
grounding terminals 17 have been described as provided in the bottom panel 
of the base 10. However, according to a fourth preferred embodiment of 
this invention shown in FIGS. 10 to 12, only one grounding terminal 40 is 
employed and is provided in the cover plate 18. In this embodiment, the 
terminals 40 and 19 are prepared from a single sheet of electroconductive 
material by the use of any known press work, for example, a metal blanking 
process, the terminals 40 and 19 being then insert-molded into the cover 
plate 18 during the manufacture of the cover plate 18 by the use of any 
known plastics molding technique. This arrangement is advantageous in that 
the digital switch assembly can be manufactured with a minimized number of 
component parts. In addition, since the terminal 40 can be fabricated 
together with the terminals 19 at one process step, the digital switch 
assembly as a whole can also be manufactured at reduced cost. 
In addition, in the fourth embodiment shown in FIGS. 10 to 12, one end 
portion of the grounding terminal 40 inside the base 10 extends, as best 
shown in FIG. 10, upwards along one side panel of the base 10 and then 
bent so as to extend beneath the top panel towards the opposite side 
panel. Spaced areas of the end portion of the grounding terminal, shown 
generally by 40a, are exposed to the outside of the base 10 through the 
respective openings 12 defined in the top panel of the base 10. The other 
end portion of the grounding terminal 40 opposite to that one end portion 
thereof is situated outside the base 10 for external electric connection 
with the ground potential. 
The digital switch assembly according to the fourth embodiment of this 
invention operates in the following manner. Assuming that one of the 
operating members 25 is depressed by the application of the external 
finger pressure thereto, the rotor 22 is stepwisely rotated in the manner 
as hereinbefore described in connection with the first embodiment of this 
invention. At this time, that is, when and so long as the operating member 
25 is depressed, the minimum distance D1 between the tip of the finger of 
the operator touching the operating member 25 and the adjacent area 40a of 
the grounding terminal 40 becomes smaller than the minimum distance D2 
between the tip of the finger of the operator and the printed circuit 
board 23 carried by the rotor 22 and, accordingly, the electrostatic 
charge built up in the body of the operator is discharged between the area 
40a of the grounding terminal 40 and the tip of the finger of the operator 
and is then grounded to the ground through the grounding terminal 40. 
In view of the foregoing, similar advantages as hereinbefore described in 
connection with the foregoing embodiments can equally be appreciated with 
the switch assembly according to the fourth embodiment of this invention. 
In the fourth embodiment shown in FIGS. 10 to 12, the grounding terminal 
has been described as embedded in the cover plate 18. However, a grounding 
terminal corresponding functionally to the grounding terminal 40 shown in 
FIGS. 10 to 12 may be constituted by an electroconductive film or layer 
which will now be described in connection with a fifth preferred 
embodiment of this invention with reference to FIGS. 13 and 14. 
Referring now to FIGS. 13 and 14, the cover plate 18 has a grounding 
terminal piece 44 secured to a lower portion of the exterior surface 
thereof so as to extend downwards in parallel relation to the output 
terminals 19. An electroconductive strip 42 is formed on the exterior 
surface of the cover plate 18 by the use of any known metal vapor 
deposition technique or a printing technique so as to extend upwards from 
the terminal piece 44 along one side portion of the cover plate 18 and 
then laterally along an upper portion of the cover plate 18 with portions 
42a thereof situated in the openings 12 in the base 10. It is to be noted 
that the terminal piece 44 is preferably secured to the cover plate 18 in 
the manner described above after the conductive strip 42 has been formed. 
The digital switch assembly according to the fifth embodiment shown in and 
described with reference to FIGS. 13 and 24 functions in a manner 
substantially similar to that of the switch assembly according to the 
fourth embodiment shown in FIGS. 10 to 12. 
In a sixth preferred embodiment shown in FIG. 15, as a terminal member 
defining the path through which the electrostatic charge built up in the 
body of the operator of the switch assembly can be discharged to the 
ground, a metal plate 46 is employed. As best shown in FIG. 15, the metal 
plate 46 has a projection or terminal piece 50, a first pair of tongues 48 
and a second pair of tongues 52, all formed integrally therewith. The 
terminal piece 50 is adapted to be connected to the ground potential. The 
first pair of the tongues 48 and the second pair of the tongues 52 
protrude at right angles to the body of the metal plate 46 in a direction 
opposite to each other, the first pair of the tongues 48 being positioned 
in the openings 12 in the top panel of the base 10 of one digital switch 
assembly and the second pair of the tongues 52 positioned in the openings 
12 in the top panel of the base 10 of the next adjacent digital switch 
assembly (not shown) when the metal plate 46 is held is position between 
the two adjacent switch assemblies which are coupled together in 
side-by-side relation to each other. 
As is the case with the foregoing embodiment, when one of the operating 
members 25 is depressed by the application of the finger pressure, the tip 
of the finger of the operator touching the one of the operating members 25 
approaches the corresponding tongue 48 and, accordingly, the electrostatic 
charge built up in the body of the operator can be discharged to the 
ground in a manner substantially similar to that in any one of the 
foregoing embodiments. 
The use of the metal plate 46 according to the embodiment shown in FIG. 15 
is advantageous in that it can be employed in association with any type of 
existing switch assemblies and may not be limited to the particular type 
of switch assembly described hereinbefore. 
The seventh and eighth embodiments of this invention shown respectively in 
FIGS. 16 to 19 and FIGS. 20 to 23 are applicable to the switch unit UN 
comprised of a plurality of digital switch assemblies SW each being of the 
construction described hereinbefore. 
Referring now to FIGS. 16 to 19, the operating panel 10a of the base 10 of 
each of the switch assemblies SW has through-holes 54 defined therein and 
extending in a direction generally parallel to the shaft 13. The 
through-holes 54 in each base 10 of the switch assemblies SW is in turn 
communicated to the outside through respective apertures 56 also defined 
in the operating panel 10a so as to extend at right angles to the 
longitudinal axis of the through-holes 54. 
As best shown in FIGS. 16 and 18, the switch unit UN is fabricated by 
connecting the switch assemblies SW in side-by-side relation to each other 
with the engagement pawls 15 of one switch assembly SW snapped into the 
corresponding engagement recesses 16 of the next adjacent switch assembly 
SW and then connecting a pair of end plates 58 and 50 to the respective 
lateral sides of the assembly of the switch assemblies SW. When the switch 
assemblies SW are so fabricated into the switch unit UN as shown in FIG. 
16, the through-holes 54 best shown in FIG. 17 in all of the bases 10 of 
the respective switch assemblies SW are axially aligned with each other, 
defining respective passages shown by 64 in FIG. 18. 
The end plate 62 has a pair of grooves 62 defined therein in spaced 
relation to each other and so as to extend in a direction at right angles 
to the associated passages 64, said grooves 62 and said passages 64 
representing a generally L-shaped configuration. Reference numeral 66 
represent generally L-shaped electroconductive rods having the respective 
opposite end portions 66a and 66b at right angles to each other. Each of 
the electroconductive rods 66 serves not only to connect the switch 
assemblies SW together so as to avoid any possible accidental separation, 
but also to define a circuit through which the electrostatic charge built 
up in the body of the operator operating any one of the operating members 
25 of the respective switch assemblies SW can be discharged to the ground. 
For this purpose, the end portion 66a of each of the electroconductive 
rods 66 is inserted through the respective passage 64 while the end 
portion 66b thereof is received in the respective groove 62, it being, 
however, to be noted that the extremity of the end portion 66b opposite to 
the end portion 66a is, after having been inserted through the passage 64, 
bent to firmly connect the switch assemblies SW together while the 
extremity of the end portion 66a opposite to the end portion 66b is 
allowed to extend a distance outwardly from the resultant switch unit UN 
for the purpose of electrical connection to the ground. 
In the embodiment described with reference to and shown in FIGS. 16 to 19, 
it will readily be seen that the circuit for the discharge of the 
electrostatic charge built up in the body of the operator can be 
established from the tip of the finger via the aperture 56 adjacent the 
finger and then through the electroconductive rod 66 also adjacent the 
finger. As best shown in FIG. 19, when one of the operating members 25 of 
any of the switch assemblies SW is depressed, the distance D2 between the 
tip of the finger of the operator and a corresponding portion of the 
electroconductive rod 66 through the respective aperture 56 becomes 
smaller than the distance D1 between the tip of the finger and the printed 
circuit board 23 and, therefore, the electrostatic charge in the body of 
the operator can advantageously be discharged to the ground in a manner 
substantially similar to that in any one of the foregoing embodiments. 
In the eighth embodiment of this invention shown in FIGS. 20 to 23, a pair 
of generally straight electroconductive rods 75 are, instead of the 
generally L-shaped rods 66 described and shown as employed in the 
foregoing embodiment as shown in FIG. 18, employed in the form as embedded 
in, or otherwise exteriorly carried by, one of the opposite end plates, 
for example, the end plate 74. As best shown in FIG. 21, each of the 
electroconductive rods 75 has one end 75a bent to protrude at right angles 
to the remaining portion thereof and forked to provide a pair of spaced 
fingers cooperable with a respective coupling element 71 as will be 
described later. While a substantially intermediate portion of each of the 
electroconductive rods 75 is embedded in, or otherwise exteriorly carried 
by, the end plate 74, the other end 75b thereof protrudes rearwardly as 
viewed in FIG. 21 to provide a respective grounding terminal. 
As best shown in FIGS. 21 and 23, the operating panel 10a of the base 10 
has a pair of spaced stepped through-holes 69 defined therein for the 
accommodation of the respective coupling elements 71 therein, which 
stepped through-holes 69 are in turn communicated to the outside of the 
base 10 through respective apertures 70 opening in the operating panel 10a 
adjacent the associated operating members 25. 
As best shown in FIGS. 22 and 23, each of the coupling elements 71 is of a 
generally Y-shaped configuration having a stem portion 71a having one end 
from which a pair of fingers 71b and 71c protrude outwards generally in 
parallel relation to each other. Each of the coupling elements 71 of the 
configuration described above is pressure-fitted into the respective 
stepped through-hole 69 with the fingers 71b and 71c situated inside such 
respective through-hole 69 and with the stem portion 71a protruding 
laterally outwardly from the operating panel 10a of the base 10. 
From the foregoing, it will readily be seen that, when a number of the 
switch assemblies SW are connected together in side-by-side relation to 
each other substantially as shown in FIG. 20, the stem portions 71a of the 
coupling elements 71 in one switch assembly are plugged respectively in 
between the fingers 71b and 71c of the coupling elements 71 in the next 
adjacent switch assembly. The complete switch unit UN can be fabricated by 
connecting the switch assemblies SW in the manner described above while 
the assembly of the switch assemblies SW are sandwiched between the end 
plates 72 and 74 as shown in FIG. 20. It is to be noted that, when the end 
plate 74 is fitted laterally to one of the connected switch assemblies SW 
which is located adjacent thereto, the stem portions 71a of the coupling 
elements 71 in such one of the connected switch assemblies SW are received 
in between the forked fingers of the ends 75a of the associated 
electroconductive rods 75. It is also to be noted that each stem portion 
71a of one coupling element 71 is plugged in between the respective 
fingers 71b and 71c of the next adjacent coupling element 71, such stem 
portion can be firmly sandwiched therebetween under the influence of the 
resiliency of the fingers 71b and 71c and, therefore, an electric circuit 
between one coupling element 71 and the next adjacent coupling element 71 
can be firmly established. This is also true of the connection between the 
stem portions 71a and the fingers in the associated electroconductive rods 
75 in the end plate 74. 
From the foregoing, it is clear that the switch unit UN comprised of the 
switch assemblies SW connected together in side-by-side relation to each 
other operates in a manner similar to the switch unit according to the 
foregoing embodiment. In any event, so far as the individual switch 
assemblies SW are concerned, each switch assembly SW operates in the 
manner as hereinbefore described in connection with the numerous foregoing 
embodiments. 
The switch unit UN according to the eighth embodiment of this invention is 
advantageous as compared with that according to the foregoing, seventh 
embodiment in that, while in the seventh embodiment the number of the 
switch assemblies to be connected together to provide the switch unit is 
limited for a given size or length of each electroconductive rod 66, a 
desired number of the switch assemblies SW can be connected together and, 
therefore, electroconductive rods of different size or length need not be 
prepared beforehand. 
While the various preferred embodiments of this invention have been fully 
described, it is to be noted that the switch assembly according to the 
first and third preferred embodiments of this invention is particularly 
advantageous in that, because of the presence of a space in the circuit 
through which the electrostatic charge set up in the body of the operator 
can be discharged to the ground, the possibility that the operator may be 
shocked by the spark discharge of the electrostatic charge can be 
eliminated. 
Although this invention has fully been described in connection with the 
various preferred embodiments thereof with reference to the accompanying 
drawings, it is to be noted that various changes and modifications are 
apparent to those skilled in the art. By way of example, while reference 
has been made to the switch assembly of a type wherein the rotor is 
rotated by manipulating the operating members one at a time, this 
invention is equally applicable to a switch assembly wherein the rotor 
itself can be manually rotated. In other words, the concept of this 
invention can equally apply to a switch assembly of a construction wherein 
the rotor has a radially outwardly extending flange partly exposed to the 
outside through the operating panel of the switch casing for the access to 
the finger of the operator. 
Accordingly, such changes and modifications are, unless they depart from 
the true scope of this invention as defined by the appended claims, to be 
construed as included therein.