Computer graphics processing and selective visual display system – Display peripheral interface input device – Touch panel
Reexamination Certificate
2001-11-14
2004-03-16
Wu, Xiao (Department: 2674)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Touch panel
C349S096000, C178S018110
Reexamination Certificate
active
06707450
ABSTRACT:
This invention claims the benefit of priority to Korean Patent Application No. 2001-13538 filed Mar. 16, 2001. The present invention relates to a touch panel with a polarizer integrally formed therein, a flat panel display with a touch panel integrally formed therein, and a laminating method thereof.
BACKGROUND AND PRIOR ART
A touch screen has been known as an input device incorporated into or added to a computer, a portable transmitter, a spherical or aspherical displaying apparatus, a personal digital assistant (PDA), or the like. Although the touch screen (touch panel) is one of input devices, it has features that its input operation is simple, there is little possibility of wrong operation, and it is possible to input characters with hands, as compared with the other input devices such as a mouse or a keyboard.
As for the currently used touch panel, its concern or technical trend is being changed from a general function of an input device to high reliability, provision of a new function, durability, and a detailed technique such as fabricating technique related to a design and processing of material, substance or the like. Further, a detecting method, a structure and performance of the touch panel are well known in detail.
Considering briefly the detecting method, there is a resistive touch panel that is constructed by bonding together two sheets having different resistance components arranged such that the two sheets can be isolated by spacers and contacted with each other by a pressing action. Further, there are a capacitive touch panel, an ultrasonic wave touch panel, an optical (infrared) sensor touch panel, an electromagnetic induction touch panel, etc. Since they have properties different from each other according to their signal amplification problems or resolution differences and their degrees of difficulty of designs and fabricating techniques, the detecting methods should be determined in consideration of durability, economical efficiency and the like thereof in addition to optical property, electrical property, mechanical property, environmental resistance, input property and the like.
FIG. 1
is a sectional view showing the basic constitution of a resistive touch screen
10
. An upper substrate
20
and a lower substrate
30
are structurally bonded by an adhesive
40
having thickness of approximately 75 to approximately 200 &mgr;m with transparent conductive films
22
thereof faced to each other. The upper substrate
20
comes into contact with the lower substrate
30
by pressure applied upon depression for input. The upper substrate
20
is made of a PET film or a thin glass sheet, which is flexible. Since the thin glass sheet has an optical isotropy, it is used for reducing surface reflection of the substrate by attaching a polarizer onto the substrate. However, a plastic film having optical isotropy is recently available. Nevertheless, production costs, fabricating difficulty and physical property thereof is open to further improvement.
The detection of an input position is made by a structure configured such that the upper and lower substrates
20
,
30
with electrodes put thereinto face each other with a gap of approximately 100 to approximately 300 &mgr;m by means of dot spacers
50
, and that input signals are extracted through a connector tail. As for its operation, when the upper substrate
20
comes into contact with the lower substrate
30
on an input point and a voltage is applied between the electrodes of the lower substrate
30
, a potential gradient is produced on resistive surfaces between both electrodes. The resulting voltage is read through the electrodes of the upper substrate
20
and an X-axis input position is then calculated by a controller. Subsequently, a voltage is applied between the electrodes of the upper substrate
20
and the resulting voltage is read through the electrodes of the lower substrate
30
so as to calculate a Y-axis input position. Thus, the input point is shown on the display. By repeating the above procedures at a high rate, input positions are continuously shown on the display so that characters or lines are drawn.
Required characteristics of the touch panel are ones requested by a user in accordance with multiple purposes of the products for installing the touch panel therein. In order to meet these characteristics of the touch panel, the structure of the touch panel may be accepted to a certain extent through a partial structural modification of the touch panel. However, it is difficult to accept all the characteristics. In addition, there is a limit on acceptance of the required characteristics by means of the resistive touch panel only. Therefore, there is a need to select an optimal one of the structures or detecting methods of the touch panel suitable for the various required characteristics.
In view of the required characteristics, the resistive touch panel is suitable for daily life of the general public where the price, productivity, character writing and the like thereof have priority over all other things. An elastic wave touch panel is suitable for use in industrial equipments where the durability, optical property, insulating property, and the like thereof are of importance. Therefore, the characteristics of the touch panel depend entirely on selection of the touch panel by the user.
On the other hand, although there are many cases where an LCD is used for a display, the LCDs are classified according to usage of products because there are many types of LCDs. In order to classify the LCDs, various classifying manners are taken into consideration.
For example, it is possible to classify the LCDs into monochrome and color types, frontlight and backlight types, or STN and TFT types in view of their structures. In particular, due to the improvements of high resolution of the TFT and color yield of the frontlight LCD, there is a great demand for the touch panel to be mounted on the LCD.
In general, the length extending from an outermost periphery of a visual area of the touch panel to an outer periphery of the touch panel is called an inactive area. The miniaturization, thinness, and improvement in an effective area ratio of a screen of the products are needed. The inactive area of the LCD has been largely reduced, so that the inactive area of the touch panel should be necessarily reduced due to a limitation on an assembly structure of them, in which the dimension of the touch panel should be smaller than that of the LCD. However, the simple reduction of the inactive area of the touch screen produces problems that linearity and insulation shield of the electrodes are lowered, and it is likely that noise is produced due to easy intrusion of an electromagnetic wave and static electricity. Complementary technologies for the above problems have been continuously proposed.
The resistive touch panel is suitable for the daily life of the general public, as described above. However, the resistive touch panels still have a problem of whether it can exhibit an expected performance in combination with a display such as an LCD and meet various demands (required characteristics). This problem also applies to the other types of the touch panels.
FIG. 2
schematically shows a sectional structure manufactured by a technology of laminating the resistive touch panel onto the flat panel display according to the required characteristics thereof.
The structure of
FIG. 2
is a flat panel display constructed in such a manner that a polarizer
60
is put on the bottom of a touch panel
10
comprised of an upper sheet
21
and a lower sheet
23
, a liquid crystal display device
70
is put on the bottom of the polarizer
60
, another polarizer
80
is then put on the bottom of the liquid crystal display device
70
, and they are finally laminated together.
Here, the polarizers
60
,
80
serve to convert visible rays into linearly polarized light on both sides of the liquid crystal display device
70
of the flat panel display. To this end, the polarizers
60
,
80
are generally constructed by laminating together predeterm
Ahn Young-Soo
Cheon Tae-Ho
ATouch Co., Ltd.
Law Offices of Brian S. Steinberger , P.A.
Steinberger Brian S.
Wu Xiao
LandOfFree
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