Electricity: circuit makers and breakers – Multiple circuit control – Multiple switch
Reexamination Certificate
2003-04-18
2004-01-13
Friedhofer, Michael (Department: 2832)
Electricity: circuit makers and breakers
Multiple circuit control
Multiple switch
C200S512000, C345S173000, C178S018050
Reexamination Certificate
active
06677542
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a touch panel disposed at the front of a display for use as a display integrated input switch, and particularly to a glass-glass type touch panel.
2. Description of the Related Art
A well known prior art touch panel of the glass-glass type called resistance film system is disclosed in Japanese Published Patent Applications JA9-146707, 10-48625, and 10-133817.
FIG. 2
illustrates the construction of such the prior art touch panel in which the upper glass side and the lower glass side are shown in an exploded view. As shown, the upper glass substrate
11
is reduced in thickness as compared to the lower glass substrate
12
such that it may be easily deformed upon application of a downward finger pressure. The upper and lower glass substrates
11
and
12
are formed on their opposing surfaces with transparent films
13
and
14
, respectively of conducting material.
The transparent conducting films
13
and
14
comprise ITO (Indium Tin Oxide) films or the like to form resistance films and are provided along their opposite edges with electrodes
15
a
,
15
b
and
16
a
,
16
b
, respectively.
In the illustrated example, the electrodes
16
a
,
16
b
provided on the transparent conducting film
14
formed on the lower glass substrate
12
are arranged along the opposite edges in the X direction of the X-Y axes which correspond to two directions orthogonal to each other in a plane parallel to the face of the transparent conducting film
14
. On the other hand, the electrodes
15
a
,
15
b
provided on the transparent conducting film
13
formed on the upper glass substrate
11
are arranged along the opposite edges in the Y direction of the transparent conducting film
13
. The electrodes
15
a
,
15
b
are somewhat extended in the X direction beyond one edge of the transparent conducting film
13
to form lead-out ends
15
ax
,
15
bx
, as shown in FIG.
2
.
Formed on the lower glass substrate
12
are conducting lead-out patterns
17
a
-
17
d
or voltage application and detection. The lead-out patterns
17
a
and
17
b
are connected with the electrodes
16
a
and
16
b
, respectively while the lead-out patterns
17
c
and
17
d
have their one ends (inner ends)
17
cx
and
17
dx
extend so as to oppose to the lead-out ends
15
ax
,
15
bx
which are extensions of the electrodes
15
a
,
15
b
on the upper glass substrate
11
.
As shown, the lead-out patterns
17
a
-
17
d
extend so as to terminate in their other ends (outer ends) aligned along one side of the lower glass substrate
12
which may be connected with a FPC cable (not shown) or the like for connection with an external circuit.
The electrodes
15
a
,
15
b
,
16
a
,
16
b
and the lead-out patterns
17
a
-
17
d
may be formed by print-applying and firing a conducting paste, for which a silver paste is commonly used.
Further, it is to be noted that many dot spacers
18
are formed in an array over the transparent conducting film
14
of the lower glass substrate
12
.
The upper glass substrate
11
and the lower glass substrate
12
constructed as described above are integrally bonded together around their peripheries by means of a seal
19
having spacers incorporated therein, with the transparent conducting films
13
and
14
facing each other.
More specifically, the seal
19
comprises spacers of glass fiber or the like incorporated in a matrix of thermosetting resin such as epoxy-based resin and is applied on the lower glass substrate
12
in a frame-like fashion around its outer periphery as shown, on which the upper glass substrate
11
is superposed, followed by pressing and firing the resulting assembly to bond the upper glass substrate
11
and the lower glass substrate
12
together with a predetermined spacing therebetween.
Concurrently with this process, the lead-out ends
15
ax
,
15
bx
which are extended ends of the electrodes
15
a
,
15
b
on the upper glass substrate
11
and the opposing inner ends
17
cx
,
17
dx
of the lead-out patterns
17
c
,
17
d
on the lower glass substrate
12
are connected together by a conducting paste.
In addition, a notched portion
19
a
provided in the frame-like seal
19
is used as an air inlet for injecting air to bulge the central portion of the upper glass substrate
11
(increase the spacing from the lower glass substrate) after bonding the upper and lower glass substrates
11
and
12
together, and once the air has been injected, the notched portion is sealed.
The touch panel constructed as described above is configured such that a depressing operation on the touch panel at any point thereof will bring the transparent conducting films
13
and
14
into contact with each other at the depressed point so that when a voltage is applied to the electrodes
16
a
,
16
b
of the transparent conducting film
14
which is a resistance film at the opposite ends thereof, the potential of which is detected through the transparent conducting film
13
to determine the X coordinate of that point while in the same manner, when a voltage is applied to the electrodes
15
a
,
15
b
of the transparent conducting film
13
at the opposite ends thereof, the potential of which is detected through the transparent conducting film
14
to determine the Y coordinate of that point. The X and Y coordinates of that depressed point may thus be determined.
Heretofore, however, the well known touch panel having the construction as described above has had the disadvantage that it is quite susceptible to cracks in the relatively thin upper glass substrate
11
when the upper glass substrate
11
and the lower glass substrate
12
are bonded together by a seal
19
, resulting in being rejected as defective parts, and hence reduced yields.
As a result of researching into the causes of frequent occurrence of such cracking, the present inventor has reached the conclusion that it may be ascribable to the facts that the conducting lead-out patterns
17
a
-
17
d
intersect the seal
19
before extending outside to form intersections (overlapping portions) and that rod-like (columnar) glass fibers has heretofore been used as spacers to be admixed into the seal
19
. The situation in which the glass cracking incidental to the prior art example illustrated occurs will be specifically explained by exampling numerical values as follows:
Now assume that the spacing between the upper and lower glass substrates
11
and
12
around their periphery (seal joint) is 9 &mgr;m. In this instance, glass fibers on the order of 9 &mgr;m in diameter (&phgr;) and 30-50 &mgr;m in length have heretofore been used as spacers. That is, such glass fibers have been admixed into thermosetting resin such as epoxy-based resin to form a seal
19
.
On the other hand, the lead-out patterns
17
a
-
17
d
are formed of a silver paste, which contains silver particles with particle size of 10 &mgr;m or less, say about 6 &mgr;m.
FIG. 3
is an illustration showing the manner in which an upper glass substrate
11
is superposed on a lower glass substrate
12
with a seal
19
interposed therebetween, in which that portion of a lead-out pattern
17
a
intersecting the seal is diagrammatically shown. Specifically, a silver paste having silver particles as described above incorporated therein is print-applied and fired on a lower glass substrate
12
to form lead-out patterns (only a lead-out pattern
17
a
is shown in
FIG. 3
) to a thickness of 8-12 &mgr;m as measured in a direction perpendicular to the plane of the drawing (X direction in FIG.
2
), and then a seal
19
containing therein spacers in the form of glass fibers of 9 &mgr;m in diameter (&phgr;) and 30-50 &mgr;m in length as described above being applied around the lower glass substrate
12
in parallel to the plane of the drawing (Y direction in
FIG. 2
) so as to intersect the lead-out patterns, followed by an upper glass substrate
11
being superposed on the lower glass substrate
12
over the seal and the lead-out patterns. In the drawing, the reference numeral
21
indicates the silver
Friedhofer Michael
Gallagher & Lathrop
Hosiden Corporation
Lathrop, Esq. David N.
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