Computer graphics processing and selective visual display system – Display peripheral interface input device – Touch panel
Reexamination Certificate
2001-02-14
2003-03-04
Saras, Steven (Department: 2675)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Touch panel
C345S179000, C345S104000, C345S182000
Reexamination Certificate
active
06529188
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
The present invention relates to a touch panel which detects input coordinates in response to the change of resistance due to a push inputting manipulation and a screen input type liquid crystal display device constituted by laminating this touch panel thereto.
(2) Description of the Related Art
In a liquid crystal display device which is used as display means of a personal computer or a monitor of other device, an illumination light is irradiated to images formed on a liquid crystal panel and transmitting light or reflected light are irradiated to a display surface side so as to visualize the images.
In general, this type of liquid crystal display device uses a liquid crystal panel which inserts a liquid crystal layer into a gap defined between a pair of substrates having pixel selecting electrodes and the like at the time of laminating these substrates and forms images by changing the orientation state of liquid crystal molecules of selected pixel portions. Since the formed images per se are not in the visible state, light is given from outside and is irradiated to the liquid crystal panel and the transmitting light or the reflected light is observed.
Recently, information terminals which use this type of liquid crystal display device as display means have been widely used, wherein the information terminal is provided with a touch panel which is laminated to a screen of the liquid crystal display device (a display surface side of the liquid crystal panel which constitutes the liquid crystal display device) and inputs various information by a push manipulation through the screen.
Various types of touch panels exist in view of their operation principles and the most popular type is a type which detects input coordinates in response to a resistance change quantity, that is, a so-called analogue resistance film type.
The touch panel of this analogue resistance film type has one substrate which is disposed at an information input side constituted by a soft film such as a transparent plastic sheet and other substrate constituted by a transparent hard substrate preferably made of glass. The touch panel is further provided with resistance films on respective opposing surfaces of these two transparent substrates. In operation, a two-dimensional coordinates value is detected in response to resistance values between the resistance films of respective substrates which are brought into contact with each other by a push inputting manipulation applied from one substrate side and output terminals.
FIG. 13
is a schematic cross-sectional view which explains a schematic constitutional example of a screen input type liquid crystal display device which constitutes a liquid crystal display device provided with a touch panel. This screen input type liquid crystal display device is constituted by laminating a touch panel
4
to a liquid crystal panel
1
. Although a light guide plate
2
which constitutes an auxiliary light source device
3
is inserted between the liquid crystal display device
1
and the touch panel
4
, a screen input type liquid crystal display device which installs the auxiliary light source device
3
at the rear side of the liquid crystal display panel or a screen input type liquid crystal display device which has no auxiliary light source device
3
have been commercially available. In the drawing, numeral
3
A indicates a lamp which constitutes the auxiliary light source device
3
and numeral
3
B indicates a lamp reflection sheet which also constitutes the auxiliary light source device
3
.
FIG.
14
A and
FIG. 14B
are schematic cross-sectional views for explaining the constitution of an essential part of the touch panel and the state at the time of push inputting manipulation in FIG.
13
. In the drawing, numeral
4
A indicates an upper substrate made of a transparent film sheet and numeral
4
B indicates a lower substrate made of a glass plate. On inner surfaces of these two substrates
4
A and
4
B, an upper resistance film
11
and a lower resistance film
12
are respectively formed by coating. Further, to an input region of the lower resistance film
12
formed on the lower substrate
4
B, dot spacers
90
which prevent the upper and lower resistance films
11
,
12
from coming into contact with each other in the non-inputting manipulation state are provided. These dot spacers
90
are formed by a printing by way of a mask having given apertures or a photolithography technique using photosensitive resin or other techniques.
The resistance films
11
,
12
are respectively electrically connected with upper and lower wiring
55
,
56
formed by printing on a seal region SL disposed at an outermost periphery of the touch panel. These upper wiring
55
and the lower wiring
56
are connected with a coordinates recognition circuit provided outside through lead wires not shown in the drawing.
The upper wiring
55
and the lower wiring
56
are respectively coated with protective films (insulation films)
71
,
72
and these protective films
71
,
72
are connected with each other by means of a sealing agent (adhesive agent or adhesive sheet)
80
.
In the inside of the seal region SL, an input region AR is positioned by way of an inoperable region NR. The inoperable region NR is a portion which becomes insensitive at the time of push inputting manipulation. As shown in
FIG. 14B
, this inoperable region NR corresponds to an input invalid space which is generated when the upper substrate
4
A is deflected toward the lower substrate
4
B due to the pushing of a pen
560
which constitutes inputting means.
In general, to prevent the information inputting error at the time of push inputting manipulation with the pen
560
, an inoperable region forming member
100
′ is disposed in this inoperable region NR. That is, the inoperable region forming member
100
′ is provided such that a tip of the pen surely enters the input region AR in the state shown in FIG.
14
B.
SUMMARY OF THE INVENTION
However, with respect to the conventional touch panel having such a constitution, since a gap defined between the upper substrate
4
A and the lower substrate
4
B is large and the inoperable region forming member
100
′ disposed in the inoperable region has a rectangular cross section, the upper substrate
4
A is largely bent and deflected toward the lower substrate
4
B due to the repeated push inputting manipulation of the pen
560
. Accordingly, when the upper substrate
4
A is deflected, a bending stress is concentrated on edge portions SF of the upper protective film
71
of the upper substrate
4
A and the inoperable region forming member
100
′.
As a result of repeated concentration of the bending stress, cracks CL occur on the upper resistance film
11
at the stress concentrated portions SF and hence, there have been problems such that it gives rise to an erroneous operation in coordinates detection or the upper substrate
4
A per se suffers from damages thus giving rise to the failure in final products.
It is a first object of the present invention to provide a touch panel which can overcome the problems of the above-mentioned prior art and can prevent the upper resistance film
11
from the occurrence of cracks CL even when the push inputting manipulation is repeatedly performed and can obviate the erroneous operation in the coordinates detection, and to provide a screen input type liquid crystal display device having a high reliability which adopts such a touch panel.
To achieve the above-mentioned object, the touch panel of the present invention comprises:
an upper substrate having an upper resistance film formed on an inner surface of a soft film member,
a lower substrate having a lower resistance film formed on an inner surface of a hard plate,
a seal region for laminating the upper substrate and the lower substrate,
dot spacers disposed in a gap defined between opposing surfaces of the upper and lower resistance films,
an input region capable of obtaining a detection output which sets a contac
Alphonse Fritz
Saras Steven
LandOfFree
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