JP3870632B2 - Electronic device and liquid crystal display device - Google Patents

Description

ここで、本実施形態の液晶パネルで反射型として用いた場合に、波長λの入射光は、カバー１を通過した後、液晶パネル１０の半透過反射板１７で反射して、再びカバー１を通過して出射する。つまり、上述の経路を通過するときのカバー１と液晶パネル１０を合わせた透過率は｛Ｔ²（λ）×Ｒ（λ）｝となる。即ち、｛Ｔ²（λ）×Ｒ（λ）｝は、反射型の入射光量に対する出射光量の比を意味するので、カバー１からの出射光量は、カバー１への入射光量に透過率｛Ｔ²（λ）×Ｒ（λ）｝を掛けたものになる。
【００３２】
ところで、液晶パネル１０の白表示の際に色が混色するのを抑えるためには、視認者の視感度が最も高くなる範囲の波長（500nm〜600nm）から任意の波長φを選択し、そのときの出射光量を基準として各波長における出射光量の設定を行うと、視認者にとって表示が見やすいものとなる。
【００３３】
したがって、表１に示されるように、本実施形態では波長λに対する反射型の入射光量に対する出射光量の比を、波長φにおける入射光量に対する出射光量の比で、正規化（基準化）した値{Ｔ²（λ）×Ｒ（λ）}／{Ｔ²（φ）×Ｒ（φ）}を求めた。即ち、この値は波長φでの出射光量を基準としたときの各波長における出射光量の相対値を意味する。ここで、次式の関係式が成り立つことがわかる。
【００３４】
【数１】

ただし、(1)式において、450nm≦λ≦650nmである。
【００３５】
本実施形態では、波長φを550nmとして、この値を各波長λの光に対して求めた。表１に示されるように、｛Ｔ²（λ）×Ｒ（λ）｝の値は、入射光の波長λが580nmでの値をピークとして、波長λが450nmあるいは650nmに近づくに従って徐々に小さな値になる。従って、カバー１の透過率Ｔ（λ）を(1)式の関係を満足するように設定した場合には、カバー１からの出射光量は入射光の波長λによらずほぼ一様であることがわかる。実際、カバー１を透して液晶パネル1０を見た場合の白表示は、緑白から白になってかなり見やすくなった。
【００３６】
さらに、比較のために反射防止膜の膜厚を変化させて、カバー１の入射光の波長λに対する透過率Ｔ（λ）を下記の表２に示される値に変更した場合を考えてみる。
【００３７】
【表２】

この表２に示されるように、{Ｔ²（λ）×Ｒ（λ）}／{ Ｔ²（550nm）×Ｒ（550nm）｝の値を、各波長λの光に対して求めてみると、上記(1)式を満たさないことがわかる。表２の反射型の入射光量に対する出射光量の比｛Ｔ²（λ）×Ｒ（λ）｝の値からわかるように、カバー１からの出射光量は、入射光の波長λによって大きく異なる値を示す。特に、表２に示されるように、波長λが450nm及び650nmにおける{Ｔ²（λ）×Ｒ（λ）}の値と、波長λが550nm〜590nmにおけるその値とを比較すると著しく異なっている。従って、波長λによって出射光量が著しく異なることがわかる。実際、カバー１を透して液晶パネル１０を見たときの白表示は、緑白から更に緑色を強めたものとなって、見にくいものであった。
【００３８】
＜第２の実施形態＞
次に、本発明の第２の実施形態に係る電子機器について説明する。図５は、この電子機器を説明するための分解断面図である。
【００３９】
この図に示されるように、本実施形態の電子機器における液晶パネル１０は、カバー１によって保護されている点において、上述した第１の実施形態と共通である。ただし、液晶パネル１０は、液晶セル１２０の上側に、前方散乱機能をもった拡散粘着層１１４、第１の位相差フィルム１１３、第２の位相差フィルム１１２および偏光板１１１がこの順に設けられ、一方、液晶セル１２０の下側には、λ／４位相差フィルム１１５、偏光板１１６、この順に設けられて構成される点において上述した第１の実施形態と相違している。さらに光源１７０が液晶パネル１０の下側に設けられている。
【００４０】
また、液晶セル１２０は、２枚のガラス基板１２１、１２２がシール部材１２３によって一定の間隙を保って貼付され、この間隙内にＳＴＮ(Super Twisted Nematic)液晶１２６が封入されるとともに、ガラス基板１２１の下面（液晶側の面）には透明電極１２４が設けられる。一方、ガラス基板１２２の上面（液晶側の面）には透明電極１２５が設けられて、ドットマトリックスを形成している点において、上述した第１の実施形態と共通である。
【００４１】
ただし、この第２実施形態において、液晶セル１２０は、赤・緑・青のカラーフィルタ１２７が、透明電極１２４とガラス基板１２１との間において、透明電極１２５の電極パターンと対向して形成される一方、スリット状の開口部を有するアルミ蒸着層１２８が、ガラス基板１２２の上面であって透明電極１２５の下面においてライン状に形成されている。これによって、アルミ蒸着層１２８は、ガラス基板１２１側からの光を反射する一方、光源１７０からの光を透過する半透過反射層として機能することになる。なお、透明電極１２４、１２５としては、第１の実施形態における透明電極２４、２５と同様に、ＩＴＯや酸化錫等が用いられる。
【００４２】
また、この液晶パネル１０では、ＳＴＮ(Super Twisted Nematic)液晶１２６に対する電圧印加・無印加に応じて、アルミ蒸着層１２８での光偏光状態が変化し、第１の位相差フィルム１１３および第２の位相差フィルム１１２によって、円偏光状態と直線偏光状態とが得られるように設定されている。また、λ／４位相差フィルム１１５は光源１７０からの光を円偏光に変換している。
【００４３】
このような構成の液晶パネル１０において、カバー１からの入射光が十分に強い場合、光源１７０を非点灯にさせて反射型として用いられる。この反射型では、カバー１からの入射光が、偏光板１１１、第２の位相差フィルム１１２、第１の位相差フィルム１１３、拡散粘着層１１４、カラーフィルタ１２７を順に通過し、アルミ蒸着層１２８によって反射されて、今来た経路を逆に辿ってカバー１から出射される。この際、透明電極１２４、１２５に印加される電圧に応じてＳＴＮ液晶１２６の配向状態が変化し、この結果、偏光板１１１からの出射光量が制御される。
【００４４】
一方、このような構成の液晶パネル１０において、カバー１からの入射光が弱い場合、光源１７０を点灯させて透過型として用いられる。この透過型では、光源１７０からの光が、偏光板１１６、λ／４位相差フィルム１１５、アルミ蒸着層１２８、カラーフィルタ１２７、拡散粘着層１１４、第１の位相差フィルム１１３、第２の位相差フィルム１１２、偏光板１１１を順に通過して、カバー１から出射される。この際、透明電極１２４、１２５に印加される電圧に応じてＳＴＮ(Super Twisted Nematic)液晶１２６の配向状態が変化し、この結果、偏光板１１１からの出射光量が制御される。
【００４５】
したがって、本実施形態の液晶パネル１０では、反射型も透過型も可能な、いわゆる半透過反射型のカラー表示が可能である。
【００４６】
ところで、本実施形態の液晶パネル１０は、電圧無印加状態において黒表示を行うノーマリーブラックモードのものである。ここで、赤・緑・青のサブ画素をオンさせて、全ての色のカラーフィルタ１２７を通過させれば、白色表示となる。
【００４７】
ここで、本実施形態の液晶パネル１０において反射型として用いた場合を考える。本実施形態の液晶パネル１０の白表示の際における分光（反射）特性を図６に示す。この図６に示されるように、本実施形態の液晶パネル１０の反射率は、各波長λの光に対してフラットな特性にはなっていないので、良好な白色特性にはなっていない。
【００４８】
そこで、本実施形態の液晶パネル１０にあっては、液晶パネル１０の表示面側の上部に、液晶パネル１０の表示面の表示部全体を覆うように、プラスチック基材の表面に反射防止膜（図示せず）が形成されたカバー１が設けられる。具体的には、プラズマ処理（アルゴンプラズマ400W×60秒）された後、基材から大気（外側）にむかって順に、材料（光学膜厚）が SiO₂（0.08λ）、ZrO₂（0.13λ）、SiO₂（0.06λ）、ZrO₂（0.25λ）、SiO₂（0.25λ）の計５層からなる反射防止多層膜が、真空蒸着法にて、成膜温度60℃の条件で膜形成されている。ここで、屈折率が互いに隣接する層相互間で異なっている。なお、設計波長λは520nmとした。これらの複数の膜の膜厚をそれぞれ設定することにより、カバー１の透過率の分光特性を設定し、カバー１が上部に設けられた液晶パネル１０の白表示を調整した。詳細には、下記の表に示すように、カバー１への入射光の波長をλとし、液晶パネル１０の反射率をＲ（λ）としたときに、反射防止膜の膜厚を変化させて、カバー１の透過率Ｔ（λ）の設定を行った。
【００４９】
【表３】

なお、この表に示されるように、{Ｔ²（λ）×Ｒ（λ）}／{ Ｔ²（550nm）×Ｒ（550nm）｝の値を、各波長λの光に対して求めて見ると、波長φを550nmとしたときの上記(1)式を満たしていることがわかる。したがって、(1)式の関係を満足するカバー１の透過率Ｔ（λ）を設定した場合には、表３の反射型の入射光量に対する出射光量の比｛Ｔ²（λ）×Ｒ（λ）｝の値からわかるように、液晶表示装置の出射光量は入射光の波長λによらずほぼ一様になる。実際に液晶パネル１０の表示面を、このように透過率Ｔ（λ）が設定されたカバー１で透かして見てみると、液晶表示装置の白表示は、液晶パネル１０のみのときと比較して、さらに白くなり見やすくなった。したがって、本実施形態においても、視認性の良い白表示とするためには、(1)式を満たすことが必要であることがわかる。
【００５０】
＜携帯電話の構成＞
さらに、本発明の電子機器として、液晶パネル１０を、携帯電話に適用した例について説明する。図７は、この携帯電話の構成を示す斜視図である。図７において、携帯電話２００は、複数の操作ボタン２０１のほか、受話口２０２、送話口２０３と共に、保護カバー１が表示面の上部に設けられた液晶パネル１０を備えるものである。なお、本実施形態では携帯電話の例を示したが、これに限られることなく、前述したカバー１及び液晶パネル１０が組み込まれる電子機器としては、図７を参照して説明した携帯電話の他、ポケットベル、ＰＨＳ、携帯用電子メール送受信器などの携帯情報端末、時計、携帯用液晶テレビ、車載用モニタ、ノート型パソコン、電子手帳、電卓、テレビ電話、ＰＯＳ端末などが挙げられる。
【００５１】
なお、本発明の電子機器に用いた液晶パネル１０の保護カバー１は、液晶パネル１０とカバー１を有してなり、液晶パネル１０にカバー１が設けられる構成とした液晶表示装置とすることも可能である。このような構成を有する液晶表示装置は、本実施形態の電子機器と同様の効果を得られることは言うまでもない。
【００５２】
【発明の効果】
以上説明したように本発明によれば、液晶パネルの表示面を保護するために設けられたカバーの少なくとも一方の面に表面反射を防止するための反射防止膜が設けられているので、カバーでの表面反射が減り、透過率が高くなる結果、反射型の液晶パネルでも明るく視認性の良い表示が得られることになる。
【図面の簡単な説明】
【図１】 本発明の第１の実施形態に係る電子機器の要部構造を説明するための図である。
【図２】 本発明の電子機器において表面反射を防ぐための原理を説明するための図である。
【図３】 本発明の第１の実施形態に係る電子機器を説明するための分解断面図である。
【図４】 本発明の第１の実施形態に係る電子機器の液晶パネルにおける白表示の際の分光（反射）特性を示す図である。
【図５】 本発明の第２の実施形態に係る電子機器を説明するための分解断面図である。
【図６】 本発明の第２の実施形態に係る電子機器の液晶パネルにおける白表示の際の分光（反射）特性を示す図である。
【図７】 カバー及び液晶パネルを適用した携帯電話の構成を例示する斜視図である。
【符号の説明】
１…カバー
２、 ３…薄膜
５…入射光
６、７…反射光
１０…液晶パネル
１１、１６、１１１、１１６…偏光板
１２…位相差フィルム
１７…半透過反射板
２０、１２０…液晶セル
２１、２２、１２１、１２２…ガラス基板
２６、 １２６…ＳＴＮ液晶
７０、１７０…光源
１２７…カラーフィルタ
１２８…アルミ蒸着層
１１２…第２の位相差フィルム
１１３…第１の位相差フィルム
１１４…拡散粘着層
１１５…λ／４位相差フィルム
２００…携帯電話
２０１…操作ボタン
２０２…受話口
２０３…送話口[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic apparatus and a liquid crystal display device including a liquid crystal panel protected by a cover.
[0002]
[Prior art]
Generally, a portable electronic device represented by a mobile phone is provided with a display device for showing various kinds of information to a user. As this type of display device, a liquid crystal panel is widely used. In particular, among liquid crystal panels, reflective liquid crystal panels with extremely low power consumption are widely used. However, since the reflection type liquid crystal panel visually recognizes the display using external light, there is a drawback that the display cannot be read in a dark place. As a display device that takes this into consideration, a so-called transflective liquid crystal panel that uses external light in a bright place in the same way as a normal reflective liquid crystal panel but can be visually recognized by an internal light source in a dark place is proposed. Has been.
[0003]
By the way, in order to prevent damage to the liquid crystal panel due to external pressure of the liquid crystal panel or intrusion of moisture into the liquid crystal panel, a cover made of transparent plastic usually covers the entire display portion of the liquid crystal panel. Is provided.
[0004]
[Problems to be solved by the invention]
However, in general, the transmittance of the cover is low, and there is a problem that the visibility of the liquid crystal panel is greatly hindered. In particular, when a reflective liquid crystal panel or a transflective liquid crystal panel is used as a reflective type, the display of the liquid crystal panel becomes dark due to this cover.
[0005]
An object of the present invention is to provide an electronic device and a liquid crystal display device including a liquid crystal panel that can obtain a bright and highly visible display by increasing the transmittance of a protective cover provided on the liquid crystal panel.
[0006]
[Means for Solving the Problems]
An electronic apparatus of the present invention includes a liquid crystal panel, a cover provided on the display surface side of the liquid crystal panel so as to cover the display surface of the liquid crystal panel, and an antireflection film provided on at least one side of the cover Both ends of the cover project from the liquid crystal panel, and inclined surfaces are formed at both ends of the cover so that the thickness decreases toward the outside of the cover. It is characterized by being. With this configuration, since an antireflection film for preventing surface reflection is provided on at least one surface of the cover, surface reflection of the cover is reduced and transmittance is increased. Thereby, a bright and highly visible display can be obtained.
[0007]
Further, it is desirable that the antireflection film is made of a thin film in which at least two layers are laminated, and the refractive indexes are different between adjacent layers. With this configuration, it is possible to further reduce the surface reflection at the cover and increase the transmittance.
[0008]
In the liquid crystal panel, liquid crystal is sandwiched between a pair of substrates, and light incident on one substrate of the pair of substrates from the other substrate side of the pair of substrates is directed to the other substrate side. It may be a liquid crystal panel having light reflecting means for reflecting. With such a structure, the liquid crystal panel can be used as a reflection type, so that the display can be visually recognized using external light, and the power consumption of the electronic device can be extremely reduced.
[0009]
Also, at this time, the wavelength of light incident from the opposite side of the cover on which the liquid crystal panel is provided is λ, the wavelength arbitrarily selected from a wavelength in the range of 500 nm to 600 nm is φ, When the transmittance for light of wavelength λ is T (λ) and the reflectance for light of wavelength λ of the liquid crystal panel is R (λ), the transmittance T (λ) of the cover is 0.7 ≦ {T (Λ) ² × R (λ)} / {T ² It is desirable to satisfy the relationship (φ) × R (φ)} ≦ 1.3 (where 450 nm ≦ λ ≦ 650 nm).
[0010]
Here, in the electronic apparatus of the present invention, when the liquid crystal panel is used as a reflection type, incident light having a wavelength λ passes through the cover, is reflected by the transflective plate of the liquid crystal panel, and passes through the cover again. Then exit. That is, the combined transmittance of the cover and the liquid crystal panel when passing through the above path is {T ² (Λ) × R (λ)}. That is, {T ² (Λ) × R (λ)} means the ratio of the amount of emitted light to the amount of incident light of the reflection type, so that the amount of emitted light from the cover depends on the transmittance {T ² (Λ) × R (λ)}.
[0011]
By the way, in order to suppress the color mixture during white display on the liquid crystal panel, an arbitrary wavelength φ is selected from a wavelength (500 nm to 600 nm) in a range where the visibility of the viewer is highest, and at that time When setting the amount of emitted light at each wavelength with the amount of emitted light as a reference, it becomes easy for the viewer to see the display.
[0012]
Therefore, {T ² (Λ) × R (λ)} / {T ² (Φ) × R (φ)} normalizes (standardizes) the ratio of the output light quantity to the reflection incident light quantity with respect to the wavelength λ by the ratio of the output light quantity to the incident light quantity at the wavelength φ in the reflective liquid crystal panel. It is the value. This value is based on the amount of emitted light at the wavelength φ as a reference and the amount of emitted light for each wavelength as a relative value with respect to the reference. If this value is 0.7 or more and 1.3 or less over the range of 450 nm ≦ λ ≦ 650 nm, when the liquid crystal panel is viewed through the cover in the reflective liquid crystal panel, the white display of the liquid crystal panel becomes good white. Means that.
[0013]
The liquid crystal display device of the present invention includes a liquid crystal panel, a cover provided on the display surface side of the liquid crystal panel so as to cover the display surface of the liquid crystal panel, and an antireflection provided on at least one side of the cover And both ends of the cover protrude from the liquid crystal panel, and inclined surfaces are formed at both ends of the cover so that the thickness decreases toward the outside of the cover. It is characterized by. With this configuration, since an antireflection film for preventing surface reflection is provided on at least one surface of the cover, surface reflection of the cover is reduced and transmittance is increased. Thereby, a bright and highly visible display can be obtained.
[0014]
Further, it is desirable that the antireflection film is made of a thin film in which at least two layers are laminated, and the refractive indexes are different between adjacent layers. With this configuration, it is possible to further reduce the surface reflection at the cover and increase the transmittance.
[0015]
In the liquid crystal panel, liquid crystal is sandwiched between a pair of substrates, and light incident on one substrate of the pair of substrates from the other substrate side of the pair of substrates is directed to the other substrate side. It may be a liquid crystal panel having light reflecting means for reflecting. With such a configuration, the liquid crystal panel can be used as a reflection type, so that the display can be visually recognized using external light, and the power consumption of the liquid crystal display device can be suppressed extremely low.
[0016]
Also, at this time, the wavelength of light incident from the opposite side of the cover on which the liquid crystal panel is provided is λ, the wavelength arbitrarily selected from a wavelength in the range of 500 nm to 600 nm is φ, When the transmittance for light of wavelength λ is T (λ) and the reflectance for light of wavelength λ of the liquid crystal panel is R (λ), the transmittance T (λ) of the cover is 0.7 ≦ {T (Λ) ² × R (λ)} / {T ² It is desirable to satisfy the relationship (φ) × R (φ)} ≦ 1.3 (where 450 nm ≦ λ ≦ 650 nm). With this configuration, if this value is 0.7 or more and 1.3 or less over the range of 450 nm ≦ λ ≦ 650 nm, the white display of the liquid crystal panel is good when the liquid crystal panel is viewed through the cover in the reflective liquid crystal panel Means white.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
First, the principle of the present invention will be described with reference to FIGS. FIG. 1 is a diagram for explaining a main structure of an electronic apparatus according to the present invention. In this figure, for the purpose of protecting the liquid crystal panel 10, the cover 1 is provided on the display surface side (upper side in FIG. 1) of the liquid crystal panel 10 so as to cover the entire display portion of the display surface of the liquid crystal panel 10. Is. The cover 1 is a rigid body based on a plastic such as acrylic resin, polycarbonate, or polyolefin. The cover 1 is hard-coated as necessary, and a thin film described below is formed on the surface thereof. That is, as shown in FIG. 2, thin films 2 and 3 having different refractive indexes are provided on the surface of the cover 1, and the surface reflected light 6 of the thin film 2 and the surface reflected light of the thin film 3 with respect to the incident light 5. 7 are set to cancel each other by interfering with each other. Thereby, reflection in the interface with the air of the cover 1 is prevented. Therefore, for convenience of explanation, hereinafter, the thin films 2 and 3 will be referred to as antireflection films.
[0018]
In addition, since the cover 1 provided with the antireflection films 2 and 3 has wavelength dependency, in actuality, as described in an embodiment described later, the film thickness is in consideration of the wavelength of the light 5 incident on the cover 1. The antireflection films 2 and 3 need to be provided on the surface of the cover 1, respectively.
[0019]
Now, examples of the coating method for forming the antireflection films 2 and 3 on the surface of the cover 1 include a vacuum deposition method, an ion plating method, and a sputtering method. In the vacuum vapor deposition method, an ion beam assist method in which an ion beam is simultaneously irradiated during vapor deposition may be used. As a film configuration, either a single-layer antireflection film or a multilayer antireflection film may be used. In the case of using a multilayer antireflection film, a structure in which at least two thin films having different refractive indexes between adjacent layers is laminated. Moreover, as a specific example of the inorganic substance used for the antireflection films 2 and 3, SiO 2 ₂ , SiO, ZrO ₂ , TiO ₂ , TiO, Ti ₂ O _Three , Ti ₂ O _Five , Al ₂ O _Three , Ta ₂ O _Five , CeO ₂ , MgO, Y ₂ O _Three , SnO ₂ , MgF ₂ , WO _Three Etc. These inorganic substances are used alone or as a mixture of two or more.
[0020]
In addition, when the antireflection films 2 and 3 are formed on the cover 1, it is desirable to perform a surface treatment of the hard coat film. Specific examples of the surface treatment include acid treatment, alkali treatment, ultraviolet irradiation treatment, plasma treatment by high frequency discharge in an argon or oxygen atmosphere, and ion beam irradiation treatment of argon, oxygen, nitrogen, or the like.
[0021]
Next, embodiments of the present invention will be described with reference to the drawings.
[0022]
<First Embodiment>
FIG. 3 is an exploded cross-sectional view for explaining the electronic apparatus according to the first embodiment of the present invention. As shown in this figure, in the electronic apparatus according to the present embodiment, the liquid crystal panel 10 is protected by a rigid cover 1. In this liquid crystal panel 10, a retardation film 12 and a polarizing plate 11 are provided in this order on the upper side of the liquid crystal cell 20, while a polarizing plate 16 and a transflective plate 17 are provided on the lower side of the liquid crystal cell 20 in this order. It is configured. Further, a light source 70 is provided below the liquid crystal panel 10.
[0023]
Here, the liquid crystal cell 20 has a configuration in which two glass substrates 21 and 22 are pasted by a seal member 23 while maintaining a certain gap, and STN (Super Twisted Nematic) liquid crystal 26 is sealed in the gap. Yes. A transparent electrode 24 is provided on the lower surface (liquid crystal side surface) of the glass substrate 21, while a transparent electrode 25 is provided on the upper surface (liquid crystal side surface) of the glass substrate 22. As the transparent electrodes 24 and 25, ITO (Indium Tin Oxide), tin oxide or the like is used.
[0024]
In the liquid crystal panel 10 having such a configuration, when the incident light from the cover 1 is sufficiently strong, the light source 70 is turned off and used as a reflection type. In this reflection type, incident light from the cover 1 sequentially passes through the polarizing plate 11, the retardation film 12, the liquid crystal cell 20, and the polarizing plate 16, is reflected by the semi-transmissive reflection plate 17, and reverses the path that has just been reached. Then, the light is emitted from the cover 1. At this time, the alignment state of the STN (Super Twisted Nematic) liquid crystal 26 changes according to the voltage applied to the transparent electrodes 24 and 25, and as a result, the amount of light emitted from the polarizing plate 11 is controlled.
[0025]
On the other hand, in the liquid crystal panel 10 having such a configuration, when the incident light from the cover 1 is weak, the light source 70 is turned on and used as a transmission type. In this transmissive type, light from the light source 70 passes through the transflective reflector 17, the polarizing plate 16, the liquid crystal cell 20, the retardation film 12, and the polarizing plate 11 in this order, and is emitted from the cover 1. At this time, the alignment state of the STN (Super Twisted Nematic) liquid crystal 26 changes according to the voltage applied to the transparent electrodes 24 and 25, and as a result, the amount of light emitted from the polarizing plate 11 is controlled.
[0026]
Therefore, in the liquid crystal panel 10 of the present embodiment, a so-called transflective black-and-white display that can be a reflective type or a transmissive type is possible.
[0027]
As described above, the rigid cover 1 according to the present embodiment covers the entire display unit of the display surface of the liquid crystal panel 10 on the display surface side of the liquid crystal panel 10 for the purpose of protecting the liquid crystal panel 10. Is provided. Further, the cover 1 is made of a plastic as a base material and is hard-coated as necessary, and an antireflection film (not shown) is formed on the surface thereof. The antireflection film is desirably formed on both surfaces of the cover 1, but may be formed on any one surface.
[0028]
By the way, the liquid crystal panel 10 of the present embodiment is of a normally white mode in which white display is performed in a state where no voltage is applied.
[0029]
Here, a case where the liquid crystal panel 10 of the present embodiment is used as a reflection type will be considered. The spectral (reflection) characteristics during white display of the liquid crystal panel 10 used in this embodiment are as shown in FIG. As shown in FIG. 4, the reflectance of the liquid crystal panel 10 of the present embodiment is high when the wavelength λ is around 550 (nm). Therefore, it can be seen that green is considerably strong when white display is performed without the cover 1 being provided.
[0030]
Therefore, in the present embodiment, the white display is adjusted in a state where the cover 1 is provided on the upper part of the liquid crystal panel 10. Here, as a specific means for adjusting white display, the film thickness of an antireflection film (not shown) provided on the cover 1 was adjusted. Specifically, as shown in Table 1 below, the wavelength of light incident on the cover 1 from the upper side (the side opposite to the liquid crystal panel side) of the cover 1 in FIG. When R (λ) is set, the transmittance T (λ) of the cover 1 is adjusted by changing the film thickness of the antireflection film.
[0031]
[Table 1]

Here, when used as a reflection type in the liquid crystal panel of the present embodiment, incident light having a wavelength λ passes through the cover 1 and is then reflected by the transflective plate 17 of the liquid crystal panel 10, so that the cover 1 is made again. Pass through and exit. That is, the combined transmittance of the cover 1 and the liquid crystal panel 10 when passing through the above path is {T ² (Λ) × R (λ)}. That is, {T ² (Λ) × R (λ)} means the ratio of the amount of emitted light to the amount of incident light of the reflection type, so that the amount of emitted light from the cover 1 has a transmittance {T ² (Λ) × R (λ)}.
[0032]
By the way, in order to suppress color mixing when the liquid crystal panel 10 displays white, an arbitrary wavelength φ is selected from a wavelength (500 nm to 600 nm) in a range where the visibility of the viewer is highest, and then When the amount of emitted light at each wavelength is set on the basis of the amount of emitted light, the display becomes easy for the viewer to see.
[0033]
Therefore, as shown in Table 1, in the present embodiment, a value obtained by normalizing (standardizing) the ratio of the output light amount to the reflection incident light amount with respect to the wavelength λ by the ratio of the output light amount to the incident light amount at the wavelength φ { T ² (Λ) × R (λ)} / {T ² (Φ) × R (φ)} was determined. That is, this value means the relative value of the emitted light quantity at each wavelength when the emitted light quantity at the wavelength φ is used as a reference. Here, it can be seen that the following relational expression holds.
[0034]
[Expression 1]

However, in the formula (1), 450 nm ≦ λ ≦ 650 nm.
[0035]
In this embodiment, the wavelength φ is set to 550 nm, and this value is obtained for light of each wavelength λ. As shown in Table 1, {T ² The value of (λ) × R (λ)} gradually decreases as the wavelength λ approaches 450 nm or 650 nm, with the peak value at the wavelength λ of incident light 580 nm. Therefore, when the transmittance T (λ) of the cover 1 is set so as to satisfy the relationship of the expression (1), the amount of light emitted from the cover 1 is almost uniform regardless of the wavelength λ of incident light. I understand. In fact, the white display when the liquid crystal panel 10 is viewed through the cover 1 has changed from green to white and is thus much easier to see.
[0036]
Further, for comparison, consider the case where the transmittance T (λ) with respect to the wavelength λ of the incident light of the cover 1 is changed to the value shown in Table 2 below by changing the thickness of the antireflection film.
[0037]
[Table 2]

As shown in Table 2, {T ² (Λ) × R (λ)} / {T ² When the value of (550 nm) × R (550 nm)} is obtained for light of each wavelength λ, it can be seen that the above equation (1) is not satisfied. The ratio of the output light quantity to the reflection type incident light quantity in Table 2 {T ² As can be seen from the value of (λ) × R (λ)}, the amount of light emitted from the cover 1 varies greatly depending on the wavelength λ of the incident light. In particular, as shown in Table 2, {T at wavelengths λ of 450 nm and 650 nm. ² Comparing the value of (λ) × R (λ)} with the value at a wavelength λ of 550 to 590 nm is significantly different. Therefore, it can be seen that the amount of emitted light varies significantly depending on the wavelength λ. Actually, the white display when the liquid crystal panel 10 is viewed through the cover 1 is not easy to see because green is further enhanced from green to white.
[0038]
<Second Embodiment>
Next, an electronic apparatus according to a second embodiment of the present invention will be described. FIG. 5 is an exploded cross-sectional view for explaining the electronic apparatus.
[0039]
As shown in this figure, the liquid crystal panel 10 in the electronic apparatus of the present embodiment is common to the above-described first embodiment in that it is protected by a cover 1. However, the liquid crystal panel 10 is provided with a diffusion adhesive layer 114 having a forward scattering function, a first retardation film 113, a second retardation film 112, and a polarizing plate 111 in this order on the upper side of the liquid crystal cell 120. On the other hand, the liquid crystal cell 120 is different from the above-described first embodiment in that the λ / 4 retardation film 115, the polarizing plate 116, and the liquid crystal cell 120 are provided in this order. Further, a light source 170 is provided below the liquid crystal panel 10.
[0040]
Further, in the liquid crystal cell 120, two glass substrates 121 and 122 are pasted by a sealing member 123 while maintaining a certain gap, and STN (Super Twisted Nematic) liquid crystal 126 is sealed in the gap, and the glass substrate 121 is also sealed. A transparent electrode 124 is provided on the lower surface (surface on the liquid crystal side). On the other hand, the transparent electrode 125 is provided on the upper surface (surface on the liquid crystal side) of the glass substrate 122 to form a dot matrix, which is the same as the first embodiment described above.
[0041]
However, in the second embodiment, the liquid crystal cell 120 is formed with the red, green, and blue color filters 127 facing the electrode pattern of the transparent electrode 125 between the transparent electrode 124 and the glass substrate 121. On the other hand, an aluminum vapor deposition layer 128 having a slit-shaped opening is formed in a line shape on the upper surface of the glass substrate 122 and on the lower surface of the transparent electrode 125. Thus, the aluminum vapor deposition layer 128 functions as a semi-transmissive reflective layer that reflects light from the glass substrate 121 side and transmits light from the light source 170. As the transparent electrodes 124 and 125, ITO, tin oxide, or the like is used similarly to the transparent electrodes 24 and 25 in the first embodiment.
[0042]
Further, in this liquid crystal panel 10, the light polarization state in the aluminum vapor deposition layer 128 changes depending on whether a voltage is applied or not applied to the STN (Super Twisted Nematic) liquid crystal 126, and the first retardation film 113 and the second retardation film 113 are changed. The retardation film 112 is set so that a circularly polarized state and a linearly polarized state can be obtained. The λ / 4 retardation film 115 converts light from the light source 170 into circularly polarized light.
[0043]
In the liquid crystal panel 10 having such a configuration, when the incident light from the cover 1 is sufficiently strong, the light source 170 is turned off and used as a reflection type. In this reflection type, incident light from the cover 1 sequentially passes through the polarizing plate 111, the second retardation film 112, the first retardation film 113, the diffusion adhesive layer 114, and the color filter 127, and the aluminum vapor deposition layer 128. , And then exits the cover 1 following the path that has just come. At this time, the alignment state of the STN liquid crystal 126 changes according to the voltage applied to the transparent electrodes 124 and 125, and as a result, the amount of light emitted from the polarizing plate 111 is controlled.
[0044]
On the other hand, in the liquid crystal panel 10 having such a configuration, when the incident light from the cover 1 is weak, the light source 170 is turned on and used as a transmission type. In this transmissive type, light from the light source 170 is transmitted through the polarizing plate 116, the λ / 4 retardation film 115, the aluminum vapor deposition layer 128, the color filter 127, the diffusion adhesive layer 114, the first retardation film 113, and the second position. The light passes through the phase difference film 112 and the polarizing plate 111 in this order and is emitted from the cover 1. At this time, the alignment state of STN (Super Twisted Nematic) liquid crystal 126 changes according to the voltage applied to transparent electrodes 124 and 125, and as a result, the amount of light emitted from polarizing plate 111 is controlled.
[0045]
Therefore, in the liquid crystal panel 10 of the present embodiment, a so-called transflective color display that can be a reflective type or a transmissive type is possible.
[0046]
By the way, the liquid crystal panel 10 of the present embodiment is of a normally black mode in which black display is performed when no voltage is applied. Here, when the red, green, and blue sub-pixels are turned on to pass through the color filters 127 of all colors, white display is obtained.
[0047]
Here, a case where the liquid crystal panel 10 of the present embodiment is used as a reflection type will be considered. FIG. 6 shows the spectral (reflection) characteristics when the liquid crystal panel 10 of the present embodiment displays white. As shown in FIG. 6, the reflectance of the liquid crystal panel 10 of the present embodiment does not have a flat characteristic with respect to light of each wavelength λ, and therefore does not have a good white characteristic.
[0048]
Therefore, in the liquid crystal panel 10 according to the present embodiment, an antireflection film (on the surface of the plastic substrate is formed on the display surface side of the liquid crystal panel 10 so as to cover the entire display portion of the display surface of the liquid crystal panel 10. A cover 1 having a not-shown structure is provided. Specifically, after the plasma treatment (argon plasma 400W × 60 seconds), the material (optical film thickness) is changed to SiO (in order) from the base material to the atmosphere (outside). ₂ (0.08λ), ZrO ₂ (0.13λ), SiO ₂ (0.06λ), ZrO ₂ (0.25λ), SiO ₂ An antireflection multilayer film composed of a total of 5 layers (0.25λ) is formed by a vacuum vapor deposition method under a film forming temperature of 60 ° C. Here, the refractive index is different between adjacent layers. The design wavelength λ was 520 nm. By setting the film thickness of each of these films, the spectral characteristics of the transmittance of the cover 1 were set, and the white display of the liquid crystal panel 10 provided with the cover 1 was adjusted. Specifically, as shown in the following table, when the wavelength of the incident light to the cover 1 is λ and the reflectance of the liquid crystal panel 10 is R (λ), the thickness of the antireflection film is changed. The transmittance T (λ) of the cover 1 was set.
[0049]
[Table 3]

As shown in this table, {T ² (Λ) × R (λ)} / {T ² When the value of (550 nm) × R (550 nm)} is obtained for each wavelength λ, it can be seen that the above equation (1) when the wavelength φ is 550 nm is satisfied. Therefore, when the transmittance T (λ) of the cover 1 that satisfies the relationship of the expression (1) is set, the ratio of the output light quantity to the reflection type incident light quantity in Table 3 {T ² As can be seen from the value of (λ) × R (λ)}, the amount of light emitted from the liquid crystal display device is substantially uniform regardless of the wavelength λ of the incident light. When the display surface of the liquid crystal panel 10 is actually viewed through the cover 1 with the transmittance T (λ) set in this way, the white display of the liquid crystal display device is compared with the case of the liquid crystal panel 10 alone. It became whiter and easier to see. Therefore, also in the present embodiment, it is understood that the expression (1) needs to be satisfied in order to achieve white display with high visibility.
[0050]
<Configuration of mobile phone>
Further, an example in which the liquid crystal panel 10 is applied to a mobile phone as an electronic apparatus of the present invention will be described. FIG. 7 is a perspective view showing the configuration of this mobile phone. In FIG. 7, a mobile phone 200 includes a plurality of operation buttons 201 and a liquid crystal panel 10 in which a protective cover 1 is provided at an upper portion of a display surface, together with a mouthpiece 202 and a mouthpiece 203. In the present embodiment, an example of a cellular phone is shown. However, the present invention is not limited to this, and the electronic device in which the cover 1 and the liquid crystal panel 10 described above are incorporated is not limited to the cellular phone described with reference to FIG. Mobile information terminals such as pagers, PHS, and portable electronic mail transceivers, watches, portable liquid crystal televisions, in-vehicle monitors, notebook computers, electronic notebooks, calculators, videophones, POS terminals, and the like.
[0051]
The protective cover 1 of the liquid crystal panel 10 used in the electronic apparatus of the present invention may be a liquid crystal display device that includes the liquid crystal panel 10 and the cover 1, and the liquid crystal panel 10 is provided with the cover 1. Is possible. It goes without saying that the liquid crystal display device having such a configuration can obtain the same effects as those of the electronic apparatus of the present embodiment.
[0052]
【The invention's effect】
As described above, according to the present invention, an antireflection film for preventing surface reflection is provided on at least one surface of the cover provided to protect the display surface of the liquid crystal panel. As a result, the surface reflection is reduced and the transmittance is increased. As a result, a bright and highly visible display can be obtained even with a reflective liquid crystal panel.
[Brief description of the drawings]
FIG. 1 is a diagram for explaining a main part structure of an electronic apparatus according to a first embodiment of the invention.
FIG. 2 is a diagram for explaining a principle for preventing surface reflection in the electronic apparatus of the invention.
FIG. 3 is an exploded cross-sectional view for explaining the electronic apparatus according to the first embodiment of the invention.
FIG. 4 is a diagram showing a spectral (reflection) characteristic at the time of white display in the liquid crystal panel of the electronic apparatus according to the first embodiment of the present invention.
FIG. 5 is an exploded cross-sectional view for explaining an electronic apparatus according to a second embodiment of the present invention.
FIG. 6 is a diagram showing spectral (reflection) characteristics at the time of white display in a liquid crystal panel of an electronic apparatus according to a second embodiment of the present invention.
FIG. 7 is a perspective view illustrating the configuration of a mobile phone to which a cover and a liquid crystal panel are applied.
[Explanation of symbols]
1 ... Cover
2, 3 ... Thin film
5 ... Incident light
6, 7 ... Reflected light
10 ... LCD panel
11, 16, 111, 116 ... Polarizing plate
12 ... retardation film
17 ... Transflective reflector
20, 120 ... Liquid crystal cell
21, 22, 121, 122 ... glass substrate
26, 126 ... STN liquid crystal
70, 170 ... Light source
127 Color filter
128 ... Aluminum vapor deposition layer
112 ... Second retardation film
113 ... 1st phase difference film
114 ... diffusion adhesive layer
115 ... λ / 4 retardation film
200 ... mobile phone
201 ... operation buttons
202 ... earpiece
203 ... Mouthpiece

Claims (8)

LCD panel,
A cover provided on the display surface side of the liquid crystal panel so as to cover the display surface of the liquid crystal panel;
An antireflection film provided on at least one side of the cover,
Both ends of the cover protrude from the liquid crystal panel, and inclined surfaces are formed at both ends of the cover so that the thickness decreases toward the outside of the cover. machine.   The electronic device according to claim 1, wherein the antireflection film is formed of a thin film in which at least two layers are laminated, and refractive indexes are different between adjacent layers.   The liquid crystal panel has a liquid crystal sandwiched between a pair of substrates, and reflects light incident on one substrate of the pair of substrates from the other substrate side of the pair of substrates to the other substrate side. The electronic apparatus according to claim 1, further comprising a light reflecting unit. The wavelength of light incident from the opposite side of the cover where the liquid crystal panel is provided is λ,
A wavelength arbitrarily selected from wavelengths in the range of 500 nm to 600 nm is φ,
The transmittance of the cover with respect to light having a wavelength λ is T (λ),
When the reflectance of the liquid crystal panel with respect to light of wavelength λ is R (λ),
The transmittance T (λ) of the cover is
The relationship of 0.7 ≦ {T (λ) 2 × R (λ)} / {T 2 (φ) × R (φ)} ≦ 1.3 (where 450 nm ≦ λ ≦ 650 nm) is satisfied. The electronic device described. LCD panel,
A cover provided on the display surface side of the liquid crystal panel so as to cover the display surface of the liquid crystal panel;
An antireflection film provided on at least one side of the cover,
Both ends of the cover protrude from the liquid crystal panel, and inclined surfaces are formed at both ends of the cover so that the thickness decreases toward the outside of the cover. Display device.   The liquid crystal display device according to claim 5, wherein the antireflection film is formed of a thin film in which at least two layers are laminated, and refractive indexes are different between adjacent layers.   The liquid crystal panel has a liquid crystal sandwiched between a pair of substrates, and reflects light incident on one substrate of the pair of substrates from the other substrate side of the pair of substrates to the other substrate side. 7. The liquid crystal display device according to claim 5, further comprising light reflecting means. The wavelength of light incident from the opposite side of the cover where the liquid crystal panel is provided is λ,
A wavelength arbitrarily selected from wavelengths in the range of 500 nm to 600 nm is φ,
The transmittance of the cover with respect to light having a wavelength λ is T (λ),
When the reflectance of the liquid crystal panel with respect to light of wavelength λ is R (λ),
The transmittance T (λ) of the cover is
8. The relationship of 0.7 ≦ {T (λ) 2 × R (λ)} / {T 2 (φ) × R (φ)} ≦ 1.3 (where 450 nm ≦ λ ≦ 650 nm) is satisfied. The liquid crystal display device described.

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