Liquid crystal cells – elements and systems – Liquid crystal system – Liquid crystal writing tablet
Reexamination Certificate
2001-04-20
2004-04-13
Flynn, Nathan J. (Department: 2826)
Liquid crystal cells, elements and systems
Liquid crystal system
Liquid crystal writing tablet
C349S023000, C349S024000, C349S058000, C349S156000, C349S158000, C349S162000, C349S122000
Reexamination Certificate
active
06721019
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a screen input type display device having a construction in which a touch panel, which detects input coordinates based on a change of resistance produced by a push manipulation, is laminated on a display device.
As an example, it is known to use a liquid crystal display device as a display means in a personal computer or as another type of monitor. This type of display device irradiates illumination light to form images on a liquid crystal panel, and it visualizes the images by irradiating transmitting light or reflection light to a display surface side.
In general, a screen input type display device which adopts this type of liquid crystal display uses a liquid crystal panel which sandwiches a liquid crystal layer in a space defined between a pair of laminated substrates having pixel selecting electrodes and the like, and it can generate images by changing the orientation state of liquid crystal molecules corresponding to selected pixel portions. Since the generated image per se is not in the visible state, the liquid crystal panel is irradiated by applying light from the outside, and transmitting light or reflection light therefrom is observed as the image.
Recently, an information terminal, which uses this type of liquid crystal display device as a display means and is provided with a touch panel, which is laminated on a screen of the liquid crystal display device and inputs various information through the screen by a push manipulation, has been widely used.
Although there exist touch panels for various systems depending on the operating principles thereof, the most popular touch panel is one which adopts a system in which input coordinates are detected depending on a change in the quantity of resistance, i.e. a so-called “analogue resistance film system”.
In this touch panel based on an analogue resistance film system, one substrate, which forms an information input side, is constituted of a soft film, such as a transparent plastic sheet or the like, while the other substrate is constituted of a transparent hard plate, preferably made of glass, and the resistance films are respectively provided on opposing surfaces of the two transparent substrates. With such a construction, a two dimensional coordinate value is detected based on the resistance value between the resistance films of the respective substrates, which are brought into contact with each other in response to the push manipulation applied from one substrate side, and an output terminal.
FIG. 18
is a schematic cross-sectional view illustrating an example of an overall constitution of a screen input type display device which constitutes a display device provided with a touch panel. This display device is constituted by laminating a touch panel
100
on a liquid crystal panel
300
. Although the illustrated display device is of a type which inserts an auxiliary light source device
200
between the liquid crystal panel
300
and the touch panel
100
, a display device which mounts the auxiliary light source device on a side opposite to a display screen of the liquid crystal panel
300
, or a display device which is not provided with an auxiliary light source device has been commercialized. In the drawing, numeral
202
indicates a lamp which constitutes an element of the auxiliary light source device
200
and numeral
203
indicates a lamp reflection sheet which also constitutes an element of the auxiliary light source device
200
.
FIG.
19
A and
FIG. 19B
are schematic cross-sectional views illustrating the constitution and the state at the time of push manipulation of an essential part of a signal input side of the touch panel shown in
FIG. 18
, respectively. Although the upper substrate is referred to as a first substrate and the lower substrate is referred to as a second substrate for facilitating the explanation, these substrates may be arranged up side down.
In FIG.
19
A and
FIG. 19B
, numeral
2
indicates an upper substrate made of a transparent film, such as plastic or the like, and numeral
3
indicates a lower substrate made of a hard plate, such as a glass plate. On inner surfaces of these two substrates
2
,
3
, an upper resistance film
4
and a lower resistance film
5
, which are respectively preferably made of ITO, are formed as a coating. Further, in an input region AR of the lower resistance film
5
, which is formed on the lower substrate
3
, dot-like spacers
9
which prevent upper and lower resistance films
4
,
5
from coming into contact with each other in the non-input manipulation state are formed. The spacers
9
are formed by printing using a mask having given apertures, or a photolithography technique or the like using a photosensitive resin.
In an adhesion region (seal region) SL, which is located at an outermost periphery of the touch panel, the upper resistance film
4
is electrically connected to an upper wiring electrode
6
, which is formed on the upper resistance film of the upper substrate, and an inter-substrate connection wiring electrode
7
, which is formed on the lower substrate. The inter-substrate connection wiring electrode
7
is connected to a coordinate recognition circuit disposed outside by an outgoing line (generally, a flexible printed circuit board: FPC), which is not shown in the drawing, by way of a pull-around wiring, which is also not shown in the drawing. The lower resistance film
5
, which is formed on the lower substrate
3
, is connected to a lower wiring electrode, which is not shown in the drawing, and the lower resistance film
5
is connected to the outgoing line by way of a pull-around wiring, which is not shown in the drawing and is formed on the inner surface of the lower substrate
3
.
The upper wiring electrode
6
and the inter-substrate connection wiring electrode
7
are respectively coated with protective films (insulation films)
12
A,
12
B, and these protective films are adhered to each other by means of a seal agent (adhesive agent or adhesive sheet)
13
.
Toward the inside from the seal region SL, the 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 performing the push input manipulation. As shown in
FIG. 19B
, this inoperable region NR corresponds to an input invalidation space which is formed when the upper substrate
2
is deflected toward the lower substrate
3
upon receiving the pressure of a nib
56
, which constitutes an input means.
In general, in this inoperable region NR, an inoperable region forming member
14
is provided to prevent an input failure of information by the push input manipulation of the nib
56
. That is, the inoperable region forming member
14
, which has a size that ensures the entrance of the nib
56
in the input region AR in the state shown in FIG.
19
B and is made of a transparent insulation material, is provided to the inoperable region NR.
FIG. 20
is a schematic cross-sectional view illustrating the constitution of an essential part of a connection portion between the upper wiring electrode
6
and the inter-substrate connection wiring electrode
7
of the touch panel. The upper wiring electrode
6
formed on the upper resistance film
4
on the inner surface of the upper substrate
2
and the inter-substrate connection wiring electrode
7
formed on the inner surface of the lower-substrate
3
are electrically connected with each other by way of an adhesive agent
14
made of epoxy resin in which metal particles are mixed.
In the conventional screen input type display device provided with a touch panel having such a constitution, conductive thin films made of silver paste or the like, which are coated on the upper and lower wiring connection portions, and an adhesive agent in which the metal particles are mixed are used; hence, when a gap between the upper and lower substrates is set to approximately 40 &mgr;m to 150 &mgr;m, it is difficult to control such a gap. When the gap between the upper and lower substrates is not uniform, a
Ishii Kazuo
Ishii Koji
Kakinuma Akira
Kono Masao
Otsuka Haruhisa
Antonelli Terry Stout & Kraus LLP
Erdem Fazli
Flynn Nathan J.
Hitachi , Ltd.
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