Note: Descriptions are shown in the official language in which they were submitted.
OPERATING KEY SWITCH UNIT
The present invention relates to an operating key switch
unit having a waterproof case with an electric circuit
enclosed therein, and a plurality of key switch buttons for
external operation exposed from the front of the case.
A conventional key switch unit will be described in
detail hereinbelow~
The present invention has been accomplished for
overcoming the problems of conventional key switch units and
it is the object thereoE to provide an operating key switch
unit having a sure waterproof structure not requiring an
increase in the number of panel switch fixing bolts.
The operating key switch unit according to the present
ln~ention is provided with one contactor projecting from the
inner surface of the front of the case substantially in the
; 15 same direction as the key switch button operating direction
and disposed annularly in a surrounding relation to the key
switch buttons, and the other, annular contactor formed
integrally with the panel switch and in contact with the said
~ one contactor throughout the~overall circumference at all
; 20 times.
Thus, in the present invention, since one contactor and
the other contactor are in contact with each other at all
times, there 1s not fear of the invasion of water to the
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exterior of the panel switch, namely, the interior of the
case, even when the panel switch is deformed upon depression
of a key switch button.
Fig. 1 is a perspective view showing an appearance of a
conventional key switch unit;
Fig. 2 is a sectional view taken on line II-II of Fig. l;
Fig. 3 is a partially enlarged view of Fig. 2;
Fig. 4 is a front view of a panel switch;
Fig. 5 is a side view, in longitudinal section, showing
an embodiment of the present invention;
Fig. 6 is a partially enlarged view of Fig. 5;
Fig. 7 is a front view of a panel switch;
Fig. 8 is a right-hand side view of Fig. 7;
Fig. 9 is a side view, in longitudinal section, showing
another embodiment of the present invention;
Fig. 10 i~ a partially enlarged view of Fig. 9;
Fig. 11 is a front view of a panel switch; and
Fig. 12 is a right-hand side view of Fig. 11.
A conventional operating key switch unit will now be
described with reference to Figs. 1 to 4. Fig. 1 is a
perspective view showing an appearance of the switch unit;
Fig. 2 is a sectiona] view taken on line II-II of Fig. l;
Fig. 3 is a partially enlarged view of Fig. 2; and ~ig. 4 is
a front view of a panel switch. ~n these figures, the
reference numeral 1 denotes a waterproof case molded from a
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resin; numeral 2 denotes a display opening formed in the front
indicated at la of the case l; numeral 3 denotes a button hole
formed in a plural number (twelve in the drawings) in the
front la of the case; numeral 4 denotes a printed circuit
board mounted in the case 1 using bolts 5; and numeral 6
denotes a display portion inserted in the display opening 2
between a front-side surface 4a of the printed circuit board 4
and the case front la. Numeral 7 denotes a panel switch
inserted between the front-side surface 4a of the printed
circuit board 4 and the case front la, and key switch buttons
8 for external operation exposed respectively from the button
holes 3 are formed integrally with the panel switch 7 using an
elastic material. Numeral 9 denotes an electroconductive
contact of each key switch button 8 integral with the panel
switch 7, the electroconductive contact 9 being provided in a
recess 7a. Numeral ~0 denotes a contact printed on the front-
side surface 4a of the printed circuit board 4 in an opposed
relation to each electroconductive contact 9. Numeral 11
denotes an electronic part mounted on a back-side surface 4b
of the printed circuit board 4.
The operational of the conventional key switch unit of
the above constxuction will now be explained. The panel
switch 7 is put on the printed circuit board 4 having the
electronic part 11 and fixed to the case 1 with bolts 5, As a
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result, the key switch buttons 8 of the panel switch 7 are
exposed fro~ the button holes 3 of the case so that they can
be operated from the exterior.
The contacts 10 on the printed circuit board 4 and the
electroconductive contacts 9 of the panel switch 7 jointly
form a switch structure. Both contacts g and lo are normally
not in contact with each other as shown in Fig. 3, but when a
key switch button 8 is depressed, the panel switch 7 is
deformed through the associated recess 7a, so that both
contacts are in contact with each other and as a result the
contents of operation are displayed on the display portion 6.
According to the conventional operation key switch unit
described above, the panel switch 7 is integrally formed using
an elastic material and it is sandwiched between the front-
lS side surface 4a of the printed circuit board 4 and the innersurface of the case front la, to thereby prevent the invasion
; of water from the button holes 3 to the exterior of the panel
switch 7, namely the interior of the case 1, through a
surrounding contact portion 7b of the panel switch 7.
However, the surrounding contact portion 7b of the panel
switch 7 is held by a contact pressure induced by only the
urging force of the bolts 5, so when the panel switch 7 is
deformed in response to depression of a key switch button 8,
there occurs a change in contact pressure of the surrounding
contact portion 7b, that lS, a uniform contact pressure is not
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obtained, resulting in that water enters the interior of the
case l through the surrounding contact portion 7b, thus
causing the contacts 9, 10 and the electronic part 11 to be
corroded. Further, if the mounting pitch of the bolts 5 is
made smaller to increase the contact pressure of the panel
switch 7, the resulting increase in the number of bolts 5
causes an increase in time required for the assembling
operation, thus leading to increase of cost.
An embodiment of the present invention will now be
described with reference to Figs. 5 to 8. Fig. 5 is a
sectional view similar to Fig. 2; Fig. 6 is a partially
enlarged view of Fig. 5; Fig. 7 is a front view of a panel
switch; and Fig. 8 is a right-hand side view of Fig. 7. In
these figures, portions which are the same as or equivalent to
those of the foregoing conventional switch unit are indicated
by the same reference numerals. In these figures reference
numeral 7A denotes a panel switch integrally formed using an
elastic material; numeral 12 denotes a convex portion formed
on the inner surface of a case front la. The convex portion
12 extends annularly along the marginal portion of the panel
switch 7A. Numeral 13 denotes a concave groove formed
annularly in the marginal portion of the panel switch 7A, in
which groove lS fitted the convex portion 12.
Thus, the convex portion ~2 of the case front la and
the concave groove 13 of the panel switch 7A are fitted
together. This is advantageous in that even when the panel
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switGh 7A is deformed upon depression of a key switch button
8, there will be no change in con-tact pressure between the
convex portion 12 and the concave groove 13 because both
are in contact with each other in the same direction as the
operating direction. Therefore, there is no fear of the
invasion of water to the exterior of the panel switch 7A,
namely, the interior of the case 1.
Although in the above embodiment the convex portion 12
and the concave groove 13 serve as one contactor and the
other contactor, respectively, they may be reversed.
Now, another embodiment of the present invention will
be described with reference to Figs. 9 to 12. Fig. 9 is
a sectional view similar to Fig. 5; Fig. 10 ls a partially
enlarged view of Fig. 9; Fig. 11 is a frbnt view of a panel
switch; and Fig. 12 is a right-hand side view of Fig. 11,
in which figures portions which are the same as or equivalent
to those in the previous embodiment are indica*ed by the same
~; reference numerals and~will not be~explained here. In these
figures, the numeral 7B denotes a panel switch integrally
formed using an elastic material, and numeral 12A denotes
a convex portion formed on the inner surface of the case
front la, the convex portion 12A being located annularly
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surrounding the outer periphery of the panel switch 7B and
in contact with a front-side surface 4a of the printed circuit
:
board 4. Numeral 14 denotes a rib formed annularly on the
outer periphery of the panel swi~ch 7B and in contact with
the lnner peripheral surface of the convex portion 12A.
b
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Although in this embodiment the convex portion 12A and
the rib 14 serve as one and the other contactor, respectively,
they may be reversed.
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