(19) United States
`(12) Patent Application Publication (10) Pub. No.: US 2004/0239641A1
`Takahata et al.
`(43) Pub. Date:
`Dec. 2, 2004
`
`US 2004O239641A1
`
`(54) TOUCH PANEL HAVING HIGH DURABILITY
`(76) Inventors: Kazuhiko Takahata, Kyoto (JP);
`Takao Hashimoto, Kyoto (JP);
`Kazuhiro Nishikawa, Kyoto (JP);
`Takeshi Asakura, Kyoto (JP)
`Correspondence Address:
`WENDEROTH, LIND & PONACK, L.L.P.
`2033 K STREET N. W.
`SUTE 800
`WASHINGTON, DC 20006-1021 (US)
`(21) Appl. No.:
`10/488,558
`
`(22) PCT Filed:
`
`Sep. 5, 2002
`
`(86) PCT No.:
`
`PCT/JP02/09009
`
`Foreign Application Priority Data
`(30)
`Sep. 6, 2001 (JP)...................................... 2001-269749
`Publication Classification
`(51) Int. Cl." ....................................................... G09G 5/00
`(52) U.S. Cl. .............................................................. 345/173
`
`(57)
`
`ABSTRACT
`
`An upper electrode plate has a 0.15 to 0.8 mm thick optically
`isotropic heat-resistant transparent resin plate having a glass
`transition temperature characteristic of not less than 150 C.
`The heat-resistant transparent resin plate is laminated
`directly or indirectly on a quarter wave plate all over their
`Surfaces.
`
`
`
`2O
`7
`2
`4.
`\
`2777 -4-
`ZZZZZZZZZZZZ22222222222222
`2)SYGGG
`NNNNYNN NSN
`N
`2a a a
`
`
`
`AYA as YaYasayassawaxanarayalavratayayyaya
`
`
`
`Page 1 of 11
`
`Tianma Exhibit 1006
`
`

`

`Patent Application Publication Dec. 2, 2004 Sheet 1 of 3
`Fig. 7
`2O
`N
`/
`ZZZZZZZZZZZZZZZZ
`NNNNNNNY, NNNNNNNN
`7 % a a a
`a 4 a 2
`Saraseraasaaaaskansas 2
`2 4a 42-436-62426
`2A Ada A2 2
`
`US 2004/0239641 A1
`
`way. YYYYYY SAAAAAYAAAAAAAaaaaaaaaaa... YYYYY
`
`VAvryxv VXXYYA
`
`6
`
`
`
`2
`2 2al Alaa A2. Ala A2. A a 2x a b. 2 a 2
`
`
`
`
`
`
`
`
`
`
`
`77,7272/72
`22222222222222222422 N 2
`rxxx ryxxxxtrayarvav Vyvytsy 2
`
`ww.rwarxxswarars
`SYS
`
`Axias YAYYYY
`
`SYY
`
`Ax
`
`V
`
`Fig. 3
`
`
`
`/
`2ZZZZ222222222222222222
`Z - Z. A-Z/Z77,7777,7777, 7.2
`SNAN
`all a a 2
`2
`2 a ea ae
`Aaaaaaaaa-2
`
`A.
`hasaravahara-atharavaaravaavrauluvavas usuavruva
`7
`
`
`
`v.
`
`
`
`
`
`3
`
`Page 2 of 11
`
`

`

`4.
`2
`7
`22%22%22%22%24.2%22%22%22%2 NAN
`2 a 2 a
`Sarasa 2 2
`4.62 &&Akas &
`
`2 (2 a 42, 42. A 4% A2 ZZ
`Rare:
`
`Satavaravaarate
`
`wara Yaaaaaaraaruww.
`sa.
`
`Patent Application Publication Dec. 2, 2004 Sheet 2 of 3
`Fig. 4
`
`US 2004/0239641 A1
`
`versary rarvar-rxxxxxHxxx
`
`AA
`
`
`
`5
`
`Fig. 5
`
`
`
`
`
`
`
`2 a. A2A 2 a. A
`MMA a a AA a
`A.
`1.
`1.
`r
`Savassavaaravaar
`Warsava was
`ww
`
`N
`ZXZZZZZZZZZZZZZZZZZZYZZYZZY 27
`NNR (RNNNN,N-2 AN
`2C 222A. A. Aa A
`a za za za za 24
`
`Savava 2%
`
`Page 3 of 11
`
`

`

`Patent Application Publication Dec. 2, 2004 Sheet 3 of 3
`Fig. 7
`
`US 2004/0239641 A1
`
`
`
`2
`12
`Z242%22%22%2
`NRN NCRNXR NINEXN NXNEXNA
`(3Z2424.444
`
`www.aaaaayaaaayaaS
`
`aAYYYYYY was Axxaawa w
`
`YYYY: YakYYYYYYYYAwYYYYY.
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`6
`2
`O 9 8
`33N
`2322222 EN
`N22
`NZZZZZZZZZs
`Sise-cassasséexerfayasessery:
`
`ay
`avataaaaaaaraasax axevaavaara
`
`a ZZ
`Y.
`N
`
`7
`
`4.
`
`3
`
`Fig. 9
`
`22
`
`O 9 8
`6 2
`SZZ24222222222222222221%
`
`
`
`
`
`
`
`5
`
`2.
`s
`WNNY (YNYWXYrwynwyww.rawawa
`
`Yryvyavayawrevy
`
`7
`
`4.
`
`3
`
`Page 4 of 11
`
`

`

`US 2004/0239641 A1
`
`Dec. 2, 2004
`
`TOUCH PANEL HAVING HIGH IDURABILITY
`
`TECHNICAL FIELD
`0001. The present invention relates to a high-durability
`touch panel which is free from occurrence of deterioration of
`its antireflection characteristics due to retardation changes
`even if left under a high-temperature environment for a long
`time and which allows comfortable input operations to be
`done, and yet which is Successful in workability in assembly
`process. The panel is to be used primarily for car navigation
`or the like.
`
`BACKGROUND ART
`0002. It has conventionally been practiced that a touch
`panel is disposed at frontage of LCD, organic EL, CRT, or
`other displays, which are widely used in Such products as
`PDAS (Personal Digital Assistants), portable telephones, and
`personal computers. Basically, the touch panel is So Struc
`tured that an upper electrode plate in which an upper
`electrode made of a transparent conductive film is formed on
`its lower Surface and a lower electrode plate in which a
`lower electrode made of a transparent conductive film is
`provided on its upper Surface are adhesively fixed only at
`their non-display area portions with the two electrodes
`opposed to each other via an air layer, where by pressing a
`part of the panel Surface, the two electrodes insulated from
`each other by the air layer can be put into contact with each
`other and thereby into conduction, thus allowing an input
`operation to be performed. Also, each of the upper electrode
`plate and the lower electrode plate is formed of a single layer
`or by laminating a plurality of layerS all over.
`0003. Then, for outdoor use, in order to prevent the
`reflection of external light to improve the visibility, a low
`reflection touch panel can be used in which the upper
`electrode plate 1 is formed by laminating, in an order from
`the upper electrode 2 side, at least a quarter wave plate 9 and
`a polarizing plate 10 whose absorption axis crosses the
`optical axis of the quarter wave plate 9 at an angle of 45 or
`135 (see FIG. 4). That is, an antireflection filter of circular
`polarization type is formed by the quarter wave plate 9 and
`the polarizing plate 10 So that reflection of light incident
`from the external at the transparent conductive film is
`efficiently cut. In addition, in the case where the display is
`an LCD, with only one quarter wave plate 9, even linearly
`polarized light coming incident for display use from the
`LCD Side would be changed into circularly polarized light,
`and for this reason, a quarter wave plate whose optical axis
`perpendicularly crosses the quarter wave plate 9 in the upper
`electrode plate is further disposed in a lower electrode plate
`3 to cancel out the phase. That is, after changed into
`circularly polarized light by the quarter wave plate on the
`lower electrode 4 side, the incident light is turned back to the
`original linearly polarized light by the quarter wave plate 9
`on the upper electrode 2 side.
`0004 Recently, in the automobile industry, there have
`been wide-spreading car navigation Systems, which are used
`mainly by Screen operation by remote control, and there
`have been discussed use of a touch panel on the display
`Screen for more comfort of operability. In this case, there is
`an essential need for a touch panel having the aforemen
`tioned antireflection filter of circular polarization type to
`prevent deterioration of the visibility due to reflection of
`
`outdoor light Such as Sunlight. However, under Summer's
`direct Sunlight, vehicle interiors with windows closed may
`undergo a high-temperature environment over 70° C. In Such
`a case, if left as it is for a long time, the touch panel would
`expand, where Since the quarter wave plate 9 and the
`polarizing plate 10 in the upper electrode plate 1 differ from
`each other in the Stretching direction in the process of their
`axis formation, there is a fear that those plates result in
`mutually different expansional directions 11 in the state of
`their being bonded together directly or indirectly allover (see
`FIG. 5), causing occurrence of waviness or strain in the
`upper electrode plate 1 of the touch panel. Also, under the
`high-temperature environment, Since the quarter wave plate
`9 in the upper electrode plate 1 is free to expand at central
`portions while blocked or, conversely, forcedly expanded by
`the effect of the partial bonding and fixation with the lower
`electrode plate 3 in peripheral portions, there is a fear that
`StreSS 12 may be applied only to the peripheral portions of
`the quarter wave plate 9 (see FIG. 6), causing the quarter
`wave plate 9 to be changed in retardation value in Vicinities
`of the peripheral portions of the display area and, as a result,
`impairing the antireflection characteristics.
`0005 Therefore, for use in car navigations, there has
`been provided a touch panel in which a glass plate 13 is
`disposed in the upper electrode plate 1 and bonded with the
`quarter wave plate 9 all over with a view to avoiding the
`above-described problems (see FIG. 7). By bonding the
`glass plate with the quarter wave plate 9 all over in the upper
`electrode plate 1, the quarter wave plate 9 and the polarizing
`plate 10 become almost free from occurrence of expansion
`even under a high-temperature environment over 70° C.,
`thus held in a non-wavy, non-Strained State. Also, by bond
`ing the high-rigidity glass plate with the quarter wave plate
`9 all over, stress applied to the quarter wave plate 9 is
`dispersed So that the quarter wave plate 9 becomes almost
`free from occurrence of retardation changes, thus less losing
`the antireflection characteristics.
`0006. However, the upper electrode plate 1 is a part that
`makes direct contact with the finger or pen or the like, and
`in the case where a glass plate is used in the upper electrode
`plate 1, increased thickness of the upper electrode plate 1
`would cause the input operation with the pen or finger to feel
`heavier because of the high rigidity of the glass plate. For
`comfortable input operation to be done, it is necessary to Set
`the glass thickness to an extremely thin one. Unfortunately,
`with the use of a glass plate having Such a thickness, the
`touch panel would become highly liable to fracture, So that
`the touch panel would become quite difficult to handle
`during its assembly, and moreover the glass could fracture
`during the input operation with the touch panel.
`0007 Accordingly, with a view to solving these issues, an
`object of the present invention is to provide a high-durability
`touch panel which is free from occurrence of deformation of
`its appearance configuration as well as deterioration of its
`antireflection characteristics due to retardation changes even
`if left under a high-temperature environment for a long time
`and which allows comfortable input operations to be done,
`and yet which is Successful in workability in assembly
`proceSS.
`
`DISCLOSURE OF INVENTION
`0008. In order to achieve the above object, the present
`invention has the following constitution.
`
`Page 5 of 11
`
`

`

`US 2004/0239641 A1
`
`Dec. 2, 2004
`
`0009. According to a first aspect of the present invention,
`there is provided a high-durability touch panel in which an
`upper electrode plate in which an upper electrode formed of
`a transparent conductive film is provided on its lower
`Surface and a lower electrode plate in which a lower elec
`trode formed of a transparent conductive film is provided on
`its upper Surface are bonded and fixed at regions except a
`display area So that the two electrodes are opposed to each
`other with an air layer therebetween, the upper electrode
`plate comprising a lamination of, in an order from an upper
`electrode Side, at least a quarter wave plate and a polarizing
`plate whose absorption axis crosses an optical axis of the
`quarter wave plate at an angle of 45 or 135,
`0010 wherein the upper electrode plate comprises a
`0.15 to 0.8 mm thick optically isotropic heat-resis
`tant transparent resin plate having characteristics of
`a glass transition temperature of not less than 150 C.
`and an absorption coefficient of not more than 1.3%,
`and the heat-resistant transparent resin plate is lami
`nated directly or indirectly to the quarter wave plate
`all over their Surfaces.
`0011. According to a second aspect of the present inven
`tion, there is provided the high-durability touch panel
`according to the first aspect, wherein the heat-resistant
`transparent resin plate is disposed between the quarter wave
`plate and the polarizing plate.
`0012. According to a third aspect of the present inven
`tion, there is provided the high-durability touch panel
`according to the first aspect, wherein the heat-resistant
`transparent resin plate is disposed below the quarter wave
`plate.
`0013. According to a fourth aspect of the present inven
`tion, there is provided the high-durability touch panel
`according to the first aspect, wherein the heat-resistant
`transparent resin plate is disposed above the polarizing plate.
`0.014. According to a fifth aspect of the present invention,
`there is provided the high-durability touch panel according
`to any one of the first to fourth aspects, wherein the glass
`transition temperature of the heat-resistant transparent resin
`plate is not less than 170° C.
`0.015 According to a sixth aspect of the present inven
`tion, there is provided the high-durability touch panel
`according to any one of the first to fourth aspects, wherein
`the thickness of the heat-resistant transparent resin plate is
`0.2 to 0.7 mm.
`0016. According to a seventh aspect of the present inven
`tion, there is provided the high-durability touch panel
`according to any one of the first to fourth aspects, wherein
`the absorption coefficient of the heat-resistant transparent
`resin plate is not more than 1%.
`0.017. According to an eighth aspect of the present inven
`tion, there is provided the high-durability touch panel
`according to any one of the first to fourth aspects, wherein
`a moisture-proof PET film is disposed as a satin layer with
`low-reflection and antifouling functions on the polarizing
`plate or the heat-resistant transparent resin plate, whichever
`Serves as an uppermost Surface of the upper electrode plate.
`0.018. According to a ninth aspect of the present inven
`tion, there is provided the high-durability touch panel
`according to any one of the first to fourth aspects, further
`
`comprising a Seal layer for covering at least Side-end periph
`eries of the upper electrode plate and Side-end Vicinities of
`the lower electrode plate.
`
`BRIEF DESCRIPTION OF DRAWINGS
`0019. These and other aspects and features of the present
`invention will become clear from the following description
`taken in conjunction with the preferred embodiments thereof
`with reference to the accompanying drawings, in which:
`0020 FIG. 1 is a sectional view showing a low-reflection
`touch panel having high durability according to a first
`embodiment of the present invention;
`0021
`FIG. 2 is a sectional view showing a low-reflection
`touch panel having high durability according to a Second
`embodiment of the present invention;
`0022 FIG. 3 is a sectional view showing a low-reflection
`touch panel having high durability according to a third
`embodiment of the present invention;
`0023 FIG. 4 is a sectional view showing a low-reflection
`touch panel according to a prior art;
`0024 FIG. 5 is an exploded plan view showing changes
`under a high-temperature environment with respect to the
`upper electrode plate of the low-reflection touch panel of
`FIG. 4;
`0025 FIG. 6 is a sectional view showing stress applied
`to the upper electrode plate under a high-temperature envi
`ronment with respect to the low-reflection touch panel of
`FIG. 4;
`0026 FIG. 7 is a sectional view showing a low-reflection
`touch panel having high durability according to a prior art;
`0027 FIG. 8 is a sectional view showing a low-reflection
`touch panel having high durability according to another
`embodiment of the present invention; and
`0028 FIG. 9 is a sectional view showing a low-reflection
`touch panel having high durability according to yet another
`embodiment of the present invention.
`
`BEST MODE FOR CARRYING OUT THE
`INVENTION
`0029. Before the description of the present invention
`proceeds, it is to be noted that like parts are designated by
`like reference numerals throughout the accompanying draw
`ings.
`0030 Hereinbelow, the present invention is described in
`detail with reference to the accompanying drawings. FIGS.
`1 to 3 are sectional views showing low-reflection touch
`panels having high durability according to first to third
`embodiments of the present invention. In the figures, refer
`ence numeral 1 denotes an upper electrode plate, 2 denotes
`an upper electrode, 3 denotes a lower electrode plate, 4
`denotes a lower electrode, 5 denotes an adhesive layer Such
`as double-sided adhesive tape as an example, 6 denotes an
`air layer, 7 denotes a Spacer, 8 denotes a heat-resistant
`transparent resin plate, 9 denotes a quarter wave plate, and
`10 denotes a polarizing plate.
`0031
`Basically, the touch panel is so structured that the
`upper electrode plate 1 in which the upper electrode 2 made
`of a transparent conductive film is provided on its lower
`
`Page 6 of 11
`
`

`

`US 2004/0239641 A1
`
`Dec. 2, 2004
`
`surface and the lower electrode plate 3 in which the lower
`electrode 4 made of a transparent conductive film is pro
`Vided on its upper Surface are adhesively fixed only at their
`non-display area portions with the two electrodes 1 and 3
`opposed to each other via the air layer 6. In the case of a
`low-reflection touch panel of the circular polarization type,
`the upper electrode plate 1 is implemented by one in which
`at least the quarter wave plate 9 and the polarizing plate 10
`whose absorption axis crosses the optical axis of the quarter
`wave plate 9 at an angle of 45 or 135 are laminated in an
`order from the upper electrode 2 side. Also, each of the
`upper electrode plate 1 and the lower electrode plate 3 is
`formed of a single layer or by laminating a plurality of layers
`in allover bonding. First to third embodiments of the present
`invention are characterized in that in each of Such low
`reflection touch panels, the upper electrode plate 1 has a 0.15
`to 0.8 mm thick, optically isotropic heat-resistant transparent
`resin plate 8 having a property of a glass transition tem
`perature of not less than 150° C., and that the heat-resistant
`transparent resin plate 8 is bonded directly or indirectly with
`the quarter wave plate 9 all over (see FIGS. 1 to 3). It is
`noted here that in the individual embodiments of the present
`invention, the term “plate” includes thin ones of sheets or
`films or the like.
`0.032 The quarter wave plate 9 has a function of con
`Verting linearly polarized light into circularly polarized light
`or generally circularly polarized light by giving a time-base
`phase shift (phase difference) to polarized light of mutually
`perpendicular two components resulting from decomposi
`tion of linearly polarized light, where one polarized com
`ponent is retarded in phase behind the other polarized
`component by 4 wavelength. This 4 wavelength is referred
`to a center wavelength (approx. 550 nm) of the visible
`region (approx. 400 nm to 700 nm). The quarter wave plate
`9 is given by one which is formed by uniaxially drawing a
`transparent resin plate of polycarbonate, polyarylate, poly
`etherSulfone, polysulfone, norbornene resin, or the like and
`controlling the refractive index of an X direction, which is
`the drawing direction (direction of optical axis), the refrac
`tive index of a y direction perpendicular to the X direction,
`and the refractive index of a thickneSSwise direction, i.e., a
`Z direction perpendicular to the X and y directions.
`0033. The quarter wave plate 9, in combination with the
`polarizing plate 10 of its upper Surface, forms an antireflec
`tion filter of the circular polarization type. Light from the
`external Such as an indoor fluorescent lamp or an outdoor
`light passes through the polarizing plate 10, becoming
`linearly polarized light, and is transmitted by the quarter
`wave plate 9, becoming circularly polarized light, where
`even if the light is reflected by the transparent conductive
`film, the circularly polarized light, when passing again
`through the quarter wave plate 9, changes into linearly
`polarized light vertical to the transmission axis of the
`polarizing plate 10, So that reflected light is Suppressed. In
`addition, as the quarter wave plate 9, one having flexibility
`to facilitate the input by pen or finger is used.
`0034. The polarizing plate 10 to be disposed at the upper
`surface of the quarter wave plate 9 is so formed that its
`absorption axis forms an angle of 45 or 135 with the
`optical axis 7 of the quarter wave plate 9. AS the polarizing
`plate 10, generally, one formed by drawing a polyvinyl
`alcohol plate impregnated with iodine, dye, or other dichro
`
`matic pigments and then covered with a cellulose- or acrylic
`protective coat on both sides, or another is used.
`0035. The quarter wave plate 9 and the polarizing plate
`10, and/or the quarter wave plate 9 and the heat-resistant
`transparent resin plate 8, may be bonded together directly all
`over (see FIGS. 1 to 3), or may be bonded together indirectly
`via an optically isotropic transparent resin plate. Adhesives
`to be used for the bonding may be given by acrylate ester
`copolymer or other acrylic resins, urethane resins, Silicon
`resins, rubber resins, aqueous or UV-curable adhesives, and
`the like. Also, the material of the optically isotropic trans
`parent resin plate is preferably given by ones of excellent
`transparency Such as polycarbonate, polyarylate, polyether
`Sulfone, polysulfone, and norbornene resins. It is noted that
`the term “optical isotropy” in the above embodiments of the
`present invention refers to those having a retardation value
`of not more than 10 nm, preferably not more than 5 nm.
`0036) The material of the heat-resistant transparent resin
`plate 8 is given by an optically isotropic transparent resin
`having a glass transition temperature of not less than 150 C.
`molded to a thickness of 0.15 to 0.8 mm, the optically
`isotropic transparent resin Selected from among polycarbon
`ate resins, norbornene resins, epoxy resins, Siloxane resins,
`polyarylate resins, polyetherSulfone resins, polysulfone res
`ins, ultraViolet-curable acrylic resins, epoxy acrylic resins,
`and other heat-resistant acrylic resins.
`0037. The heat-resistant transparent resin plate 8 of the
`above embodiments of the present invention, as one con
`Stituent layer of the upper electrode plate 1, is bonded
`together with the quarter wave plate 9 and the polarizing
`plate 10 all over so as to almost fully suppress the thermal
`expansion of the quarter wave plate 9 and the polarizing
`plate 10 and to thereby maintain a stable state free from
`occurrence of wavineSS and Strain under a high-temperature
`environment over 70° C. Such as in a vehicle with its
`windows closed under Summer's direct Sunlight, or even
`under high-temperature, high-humidity environments with
`the humidity over 80%. Such as on rainy days, as with glass
`plates. Accordingly, a material that will not be deformed due
`to heat even under Such high-temperature or high-humidity
`environments is required. AS indices therefor are glass
`transition temperature and absorption coefficient, an opti
`cally isotropic transparent resin plate having a glass transi
`tion temperature of not less than 150° C. and an absorption
`coefficient of not more than 1.3% can be used as the
`heat-resistant transparent resin plate 8 of each embodiment
`of the present invention. More preferably, a heat-resistant
`transparent resin plate 8 having a glass transition tempera
`ture of not less than 170° C. is used. As to the reason for
`Setting the absorption coefficient of the heat-resistant trans
`parent resin plate 8 to not more than 1.3%, if the absorption
`coefficient of the heat-resistant transparent resin plate 8 is
`beyond 1.3%, the heat-resistant transparent resin plate 8
`could be deformed due to moisture content that has pen
`etrated through the polarizing plate 10 or moisture content
`that has penetrated through side faces, and once the heat
`resistant transparent resin plate 8 has been deformed, the
`polarizing plate 10 and the quarter wave plate 9 could no
`longer be held by the heat-resistant transparent resin plate 8.
`Also, for the same reason, the upper electrode plate also
`could be deformed along with the heat-resistant transparent
`resin plate 8, which could cause the upper electrode plate to
`be brought into contact with the lower electrode plate,
`
`Page 7 of 11
`
`

`

`US 2004/0239641 A1
`
`Dec. 2, 2004
`
`resulting in occurrence of insulation failures. Conversely,
`with the absorption coefficient of the heat-resistant trans
`parent resin plate 8 set to not more than 1.3%, even if the
`heat-resistant transparent resin plate 8 is slightly deformed,
`the deformation would not cause the upper electrode plate 1
`to be brought into contact with the lower electrode plate 3,
`thus posing no problems in terms of the touch panel per
`formance.
`0.038 More preferably, the absorption coefficient of the
`heat-resistant transparent resin plate 8 is set to not more than
`1% from within the range of not more than 1.3%. The reason
`of this is that Setting the absorption coefficient to not more
`than 1% almost fully prevents the heat-resistant transparent
`resin plate 8 from deformation due to moisture content that
`has penetrated through the polarizing plate 10 or moisture
`content that has penetrated through side faces So that the
`polarizing plate 10 and the quarter wave plate 9 can be held
`more Securely by the heat-resistant transparent resin plate 8.
`0039. In contrast to this, conventionally, since such a
`heat-resistant transparent resin plate is not provided, the
`polarizing plate, upon absorption of water, would be
`deformed due to the water absorption, in which case the
`quarter wave plate could not endure the StreSS, leading to
`occurrence of deformation of the upper electrode plate, and
`resultantly nonuniformities of color might occur due to
`retardation changes. Further, the deformed upper electrode
`plate could be brought into contact with the lower electrode
`plate, bringing about insulation failures or others, which has
`been a cause of troubles in the touch panel performance.
`0040. In contrast to this, in this embodiment, by the
`disposition of the heat-resistant transparent resin plate 8
`having an absorption coefficient of not more than 1.3% as
`described above, the heat-resistant transparent resin plate 8,
`which is less affected by the moisture content that has
`penetrated through the polarizing plate 10, is leSS liable to
`deformation, allowing the resultant StreSS to be held against
`the expansion or deformation of the polarizing plate 10, and
`the upper electrode plate 1 is never brought into contact with
`the lower electrode plate 3, thus allowing the touch panel
`performance to be kept from impairments.
`0041. In order to keep the quarter wave plate 9 and the
`polarizing plate 10 in a stable State free from occurrence of
`wavineSS or Strain, the heat-resistant transparent resin plate
`8 needs to be not less than 0.15 mm thick. Even with a glass
`transition temperature of not less than 150 C., if the
`heat-resistant transparent resin plate 8 is less than 0.15 mm
`thick, the heat-resistant transparent resin plate 8 itself is not
`deformed due to heat, but cannot withstand the force with
`which the quarter wave plate 9 and the polarizing plate 10
`tend to be deformed. More preferably, a heat-resistant trans
`parent resin plate 8 having a thickness of not leSS than 0.2
`mm is used.
`0.042
`Also, the heat-resistant transparent resin plate 8 of
`each embodiment of the present invention, with its thickneSS
`Set to not more than 0.8 mm, allows the input by pen or
`finger to be done adequately lightly even when incorporated
`as one constituent layer of the upper electrode plate 1 by
`Virtue of its high flexibility as compared with glass plates.
`More preferably, a heat-resistant transparent resin plate 8
`having a thickness of not more than 0.7 mm is used. Still, the
`heat-resistant transparent resin plate 8 will not fracture,
`unlike glass plates, thus greatly facilitating the handling of
`
`the touch panel during the assembly process, and eliminat
`ing the possibility of damage during input operations with
`the touch panel. Moreover, rolling process as well becomes
`applicable, which facilitates defoaming proceSS or the like
`during the bonding process.
`0043 Table 1 below shows flexure amounts resulting
`from pressurizing the foregoing heat-resistant transparent
`resin plates A to C and a glass plate, each having a size of
`130 mmx100 mm and a glass transition temperature of 195
`C., with (p20-mm dia. Steel balls placed at the upper-Surface
`central portions.
`
`TABLE 1.
`
`Thickness
`(mm)
`O.2
`O.2
`
`0.4
`
`O.8
`
`Static
`pressure
`(gf)
`2OO
`2OO
`
`2OO
`
`2OO
`
`Flexure
`amount (mm)
`O.9
`2.7
`
`1.7
`
`1.1
`
`Glass plate
`Heat-resistant
`transparent
`resin plate A
`heat-resistant
`transparent
`resin plate B
`Heat-resistant
`transparent
`resin plate C
`
`0044) There is a triple difference in flexure amount
`between the heat-resistant transparent resin plate A and the
`glass plate, which are of the same thickness, under the same
`Static-pressure condition. The 0.2 mm thick glass plate is
`Smaller in flexure amount, even when compared with the
`heat-resistant transparent resin plate C whose thickneSS is
`increased to 0.8 mm, which is the upper limit. In order to
`enable a comfortable input operation, the glass plate needs
`to be set to a thickness of less than 0.2 mm, resulting in
`higher likelihood of fracture.
`004.5 The heat-resistant transparent resin plate 8, in the
`upper electrode plate 1, may be disposed between the quarter
`wave plate 9 and the polarizing plate 10 (see FIG.3), or may
`be disposed on one Side of the quarter wave plate 9 the closer
`to the upper electrode 2 (see FIG. 1), or may be disposed on
`one of the polarizing plate 10 farther from the upper elec
`trode 2 (see FIG. 2). Also, in these cases, an optically
`isotropic transparent resin plate may be interposed between
`the heat-resistant transparent resin plate 8 and the quarter
`wave plate 9 or the polarizing plate 10.
`0046. As the material of the transparent conductive film
`to be provided as the upper electrode 2 at the lower Surface
`of the upper electrode plate 1 as described above, thin films
`of Such metal oxides as tin oxide, indium oxide, antimony
`oxide, Zinc oxide, cadmium oxide, or ITO, and thin films of
`Such metals as gold, Silver, copper, tin, nickel, aluminum,
`and palladium. The formation method for the transparent
`conductive film onto the upper electrode plate 1 may be
`Vacuum deposition proceSS, Sputtering process, ion plating
`process, CVD process, or the like. This is applicable also to
`the transparent conductive film to be provided as the lower
`electrode 4 at the upper Surface of the lower electrode plate
`3.
`0047 Next, the lower electrode plate 3 is explained. The
`lower electrode plate 3 is formed of a single layer or by
`
`Page 8 of 11
`
`

`

`US 2004/0239641 A1
`
`Dec. 2, 2004
`
`laminating a plurality of layerS all over the Surfaces. For
`example, glass plates or laminates of these plates may be
`used in addition to the above-described optically isotropic
`transparent resin plate. Also, in the case where the display is
`an LCD, with only one quarter wave plate 9, Since linearly
`polarized light incident for display use from the LCD side
`would also be changed into circularly polarized light, a
`quarter wave plate whose optical axis perpendicularly
`crosses the quarter wave plate 9 in the upper electrode plate
`1 is further disposed in the lower electrode plate 3, by which
`the phase is canceled out. In this case, the lower electrode
`plate 3 may be formed of a single layer of the quarter wave
`plate, or may be formed of a laminates of optically isotropic
`transparent resin plates and glass plates. In addition, even in
`the case where the display is an LCD, providing a Second
`quarter wave plate on the Surface of the LCD may eliminate
`the need for providing a Second quarter wave plate in the
`lower electrode plate 3 of the touch panel of the above
`embodiments of the present invention.
`0.048
`Also, the upper electrode plate 1 in which the upper
`electrode 2 is provided and the lower electrode plate 3 in
`which the lower electrode 4 is provided are, normally,
`bonded and fixed by an adhesive layer 5 of double-sided
`adhesive tape or transparent adhesive material or the like
`only in regions other than the display area, with the air layer
`6 left in the display area. In this case, the quarter wave plate
`9 is bonded and fixed only in the non-display area regions
`directly, or indirectly via the optically isotropic transparent
`resin plate, with the lower electrode plate 3. Therefore, in
`order to maintain the antireflection characteristics of the
`low-reflection touch panel, it is necessary that StreSS will not
`be applied only to peripheral portions of the quarter wave
`plate 9 under high-temperature environments. In this
`embodiment of the present invention, Since the upper elec
`trode plate 1 has