JPH07333600A - Reflection type liquid crystal display device - Google Patents
Reflection type liquid crystal display deviceInfo
- Publication number
- JPH07333600A JPH07333600A JP6145337A JP14533794A JPH07333600A JP H07333600 A JPH07333600 A JP H07333600A JP 6145337 A JP6145337 A JP 6145337A JP 14533794 A JP14533794 A JP 14533794A JP H07333600 A JPH07333600 A JP H07333600A
- Authority
- JP
- Japan
- Prior art keywords
- liquid crystal
- electrode
- plate
- crystal layer
- display device
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 239000004973 liquid crystal related substance Substances 0.000 title claims abstract description 71
- 239000000463 material Substances 0.000 abstract description 8
- 239000011521 glass Substances 0.000 abstract description 6
- 239000011347 resin Substances 0.000 abstract description 3
- 229920005989 resin Polymers 0.000 abstract description 3
- 230000015556 catabolic process Effects 0.000 abstract 1
- 238000006731 degradation reaction Methods 0.000 abstract 1
- 239000010408 film Substances 0.000 description 36
- 239000010410 layer Substances 0.000 description 36
- 238000000034 method Methods 0.000 description 18
- 239000011159 matrix material Substances 0.000 description 9
- 229920000106 Liquid crystal polymer Polymers 0.000 description 7
- 238000000149 argon plasma sintering Methods 0.000 description 7
- 239000000975 dye Substances 0.000 description 6
- 229910052751 metal Inorganic materials 0.000 description 6
- 239000002184 metal Substances 0.000 description 6
- 239000004988 Nematic liquid crystal Substances 0.000 description 5
- 229910052782 aluminium Inorganic materials 0.000 description 5
- 230000007423 decrease Effects 0.000 description 5
- 229910052804 chromium Inorganic materials 0.000 description 4
- 210000002858 crystal cell Anatomy 0.000 description 4
- 238000001259 photo etching Methods 0.000 description 4
- 239000004065 semiconductor Substances 0.000 description 4
- 239000004642 Polyimide Substances 0.000 description 3
- 238000000151 deposition Methods 0.000 description 3
- 239000007769 metal material Substances 0.000 description 3
- 229920000515 polycarbonate Polymers 0.000 description 3
- 239000004417 polycarbonate Substances 0.000 description 3
- 229920001721 polyimide Polymers 0.000 description 3
- 229910052709 silver Inorganic materials 0.000 description 3
- 238000004544 sputter deposition Methods 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 229910004205 SiNX Inorganic materials 0.000 description 2
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- XLOMVQKBTHCTTD-UHFFFAOYSA-N Zinc monoxide Chemical compound [Zn]=O XLOMVQKBTHCTTD-UHFFFAOYSA-N 0.000 description 2
- 229910021417 amorphous silicon Inorganic materials 0.000 description 2
- 239000011324 bead Substances 0.000 description 2
- 239000004020 conductor Substances 0.000 description 2
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000003287 optical effect Effects 0.000 description 2
- -1 polyethylene terephthalate Polymers 0.000 description 2
- 239000002861 polymer material Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 238000007740 vapor deposition Methods 0.000 description 2
- 235000014692 zinc oxide Nutrition 0.000 description 2
- 239000011787 zinc oxide Substances 0.000 description 2
- ZNQVEEAIQZEUHB-UHFFFAOYSA-N 2-ethoxyethanol Chemical compound CCOCCO ZNQVEEAIQZEUHB-UHFFFAOYSA-N 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- 239000004925 Acrylic resin Substances 0.000 description 1
- 239000004977 Liquid-crystal polymers (LCPs) Substances 0.000 description 1
- 239000004952 Polyamide Substances 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 229910006404 SnO 2 Inorganic materials 0.000 description 1
- 239000004974 Thermotropic liquid crystal Substances 0.000 description 1
- 239000000987 azo dye Substances 0.000 description 1
- 239000005388 borosilicate glass Substances 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- IGARGHRYKHJQSM-UHFFFAOYSA-N cyclohexylbenzene Chemical compound C1CCCCC1C1=CC=CC=C1 IGARGHRYKHJQSM-UHFFFAOYSA-N 0.000 description 1
- 230000008021 deposition Effects 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- YGANSGVIUGARFR-UHFFFAOYSA-N dipotassium dioxosilane oxo(oxoalumanyloxy)alumane oxygen(2-) Chemical compound [O--].[K+].[K+].O=[Si]=O.O=[Al]O[Al]=O YGANSGVIUGARFR-UHFFFAOYSA-N 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000005338 frosted glass Substances 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- AMGQUBHHOARCQH-UHFFFAOYSA-N indium;oxotin Chemical compound [In].[Sn]=O AMGQUBHHOARCQH-UHFFFAOYSA-N 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 230000028161 membrane depolarization Effects 0.000 description 1
- 229910052627 muscovite Inorganic materials 0.000 description 1
- 238000000059 patterning Methods 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 238000000623 plasma-assisted chemical vapour deposition Methods 0.000 description 1
- 229920003055 poly(ester-imide) Polymers 0.000 description 1
- 229920003229 poly(methyl methacrylate) Polymers 0.000 description 1
- 229920002037 poly(vinyl butyral) polymer Polymers 0.000 description 1
- 229920000058 polyacrylate Polymers 0.000 description 1
- 229920002647 polyamide Polymers 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920000139 polyethylene terephthalate Polymers 0.000 description 1
- 239000005020 polyethylene terephthalate Substances 0.000 description 1
- 229920006254 polymer film Polymers 0.000 description 1
- 229920000193 polymethacrylate Polymers 0.000 description 1
- 239000004926 polymethyl methacrylate Substances 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- 238000009751 slip forming Methods 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000000758 substrate Substances 0.000 description 1
- 229920003051 synthetic elastomer Polymers 0.000 description 1
- 229910052715 tantalum Inorganic materials 0.000 description 1
- 230000007704 transition Effects 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/13356—Structural association of cells with optical devices, e.g. polarisers or reflectors characterised by the placement of the optical elements
- G02F1/133565—Structural association of cells with optical devices, e.g. polarisers or reflectors characterised by the placement of the optical elements inside the LC elements, i.e. between the cell substrates
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
- G02F1/1333—Constructional arrangements; Manufacturing methods
- G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
- G02F1/13363—Birefringent elements, e.g. for optical compensation
- G02F1/133638—Waveplates, i.e. plates with a retardation value of lambda/n
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
- G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour
- G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells
- G02F1/137—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering
- G02F1/13725—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour based on liquid crystals, e.g. single liquid crystal display cells characterised by the electro-optical or magneto-optical effect, e.g. field-induced phase transition, orientation effect, guest-host interaction or dynamic scattering based on guest-host interaction
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F2203/00—Function characteristic
- G02F2203/02—Function characteristic reflective
Landscapes
- Liquid Crystal (AREA)
- Devices For Indicating Variable Information By Combining Individual Elements (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は外光の反射を用いて表示
を行う反射型液晶表示装置に関し、特に偏光板を用いな
い明るい反射型液晶表示装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective liquid crystal display device for displaying by utilizing reflection of external light, and more particularly to a bright reflective liquid crystal display device which does not use a polarizing plate.
【０００２】[0002]
【従来の技術】従来、反射型液晶表示装置として２枚の
偏光板の間に液晶を挟さみ液晶の複屈折を利用して表示
を行うＴｗｉｓｔｅｄ Ｎｅｍａｔｉｃ方式（以下ＴＮ
方式）やＳｕｐｅｒ Ｔｗｉｓｔｅｄ Ｎｅｍａｔｉｃ
方式（以下ＳＴＮ方式）が用いられている。これらの方
式では偏光板により外光の少なくとも５０％が吸収され
るため、表示が暗く視認性が悪いという問題があった。
これに対して２色性色素を含む液晶と１／４波長の位相
差を持つ位相差板とを利用する、いわゆるλ／４ゲスト
−ホスト方式（以下「λ／４ＧＨ方式」という）の反射
型液晶表示装置は、偏光板を用いないため明るい表示が
得られることが知られている（特開昭５２−１２９４５
０号、特公昭５９−４８３９２号、特公平３−１６４９
号公報等参照）。2. Description of the Related Art Conventionally, as a reflection type liquid crystal display device, a liquid crystal is sandwiched between two polarizing plates and a display is performed by utilizing birefringence of the liquid crystal (hereinafter, referred to as TN).
Method) and Super Twisted Nematic
The method (hereinafter referred to as STN method) is used. In these methods, since at least 50% of external light is absorbed by the polarizing plate, there is a problem that the display is dark and the visibility is poor.
On the other hand, a so-called λ / 4 guest-host system (hereinafter referred to as “λ / 4GH system”) reflection type that utilizes a liquid crystal containing a dichroic dye and a retardation plate having a phase difference of ¼ wavelength. It is known that a liquid crystal display device can obtain a bright display because it does not use a polarizing plate (Japanese Patent Laid-Open No. 12945/1987).
No. 0, Japanese Patent Publication No. 59-48392, Japanese Patent Publication No. 3-1649
No.
【０００３】図５を用いて従来のλ／４ＧＨ方式の反射
型液晶表示装置を説明する。従来のλ／４ＧＨ方式の反
射型液晶表示装置は、液晶セル１、位相差板３０、およ
び反射板２０とからなる。液晶セル１は、電極２１と配
向膜４１とが順次形成された支持板１１と、電極２２と
配向膜４２とが順次形成された支持板１２と、これらの
間に挟まれた液晶層５０とからなる。位相差板３０の位
相差は可視光に対して１／４波長となるように設定さ
れ、白雲母、水晶などの無機結晶やポリビニルアルコー
ル、ポリメチルメタクリレート、ポリカーボネートなど
高分子材料の延伸フィルムなどが使用される。反射板２
０には、Ａｌ、Ａｇ、Ｃｒなど高反射率の金属材料が、
電極２１，２２にはＳｎＯ2やＩｎ2Ｏ3などの透光性導
電材料が利用される。液晶層５０には２色性色素を含む
ネマチック液晶が用いられる。液晶層５０の配向方向
は、電圧無印加時に支持板面に平行で、かつ位相差板３
０の光学軸と４５°をなすよう規定する。具体的にはラ
ビング処理した高分子膜よりなる配向膜４１，４２を設
けることにより前記の配向を実現することができる。液
晶層５０には電圧印加時に支持板面に垂直に配向するよ
うに誘電異方性が正のネマチック液晶を用いる。A conventional λ / 4GH type reflective liquid crystal display device will be described with reference to FIG. A conventional λ / 4GH type reflective liquid crystal display device includes a liquid crystal cell 1, a retardation plate 30, and a reflective plate 20. The liquid crystal cell 1 includes a support plate 11 on which an electrode 21 and an alignment film 41 are sequentially formed, a support plate 12 on which an electrode 22 and an alignment film 42 are sequentially formed, and a liquid crystal layer 50 sandwiched therebetween. Consists of. The retardation of the retardation plate 30 is set to be 1/4 wavelength with respect to visible light, and an inorganic crystal such as muscovite or quartz or a stretched film of a polymer material such as polyvinyl alcohol, polymethylmethacrylate, or polycarbonate may be used. used. Reflector 2
0 is a metal material with high reflectance such as Al, Ag, and Cr,
A transparent conductive material such as SnO 2 or In 2 O 3 is used for the electrodes 21 and 22. A nematic liquid crystal containing a dichroic dye is used for the liquid crystal layer 50. The alignment direction of the liquid crystal layer 50 is parallel to the support plate surface when no voltage is applied, and the retardation plate 3
It is specified to form 45 ° with the optical axis of 0. Specifically, the alignment can be realized by providing alignment films 41 and 42 made of a rubbing-treated polymer film. A nematic liquid crystal having a positive dielectric anisotropy is used for the liquid crystal layer 50 so as to be aligned perpendicular to the surface of the support plate when a voltage is applied.
【０００４】次にλ／４ＧＨ方式の反射型液晶表示装置
の原理を説明する。電圧無印加時には液晶層５０は支持
板面に平行に配向している。外部から支持板１１を通し
て液晶層５０に入射する光線のうち、液晶層５０の配向
方向と平行な振動面を持つ偏光成分は吸収を受け、それ
に直交する偏光成分は液晶層５０を透過する。液晶層５
０を透過した光線は位相差板３０を透過し、反射板２０
で反射され、再び位相差板３０を透過した後に、液晶の
配向方向と平行な振動面を持つ直線偏光となる。このた
め外部から入射した光はすべて液晶層５０に吸収され暗
表示となる。一方、電圧印加時には液晶層５０は支持板
面に垂直に配向する。外部から入射した光はほとんど吸
収を受けないため明表示となる。電圧無印加時の液晶層
５０の配向にねじれ配向を用いても同様の表示効果が得
られる。また誘電異方性が負のネマチック液晶と垂直配
向膜とを用いて、電圧無印加時に明表示となり、電圧印
加時に暗表示とすることもできる。Next, the principle of the λ / 4GH type reflective liquid crystal display device will be described. When no voltage is applied, the liquid crystal layer 50 is aligned parallel to the support plate surface. Of the light rays incident on the liquid crystal layer 50 from the outside through the support plate 11, the polarized light component having a vibrating plane parallel to the alignment direction of the liquid crystal layer 50 is absorbed, and the polarized light component orthogonal thereto is transmitted through the liquid crystal layer 50. Liquid crystal layer 5
The light ray that has passed through 0 passes through the retardation plate 30 and is reflected by the reflection plate 20.
After being reflected by and then transmitted through the retardation plate 30 again, it becomes a linearly polarized light having a vibrating plane parallel to the alignment direction of the liquid crystal. Therefore, all the light incident from the outside is absorbed by the liquid crystal layer 50, resulting in a dark display. On the other hand, when a voltage is applied, the liquid crystal layer 50 is aligned perpendicular to the surface of the support plate. Light incident from the outside is hardly absorbed, and thus a bright display is obtained. The same display effect can be obtained by using twisted orientation for the orientation of the liquid crystal layer 50 when no voltage is applied. Further, by using a nematic liquid crystal having a negative dielectric anisotropy and a vertical alignment film, it is possible to provide bright display when no voltage is applied and dark display when voltage is applied.
【０００５】[0005]
【発明が解決しようとする課題】しかし、このようなλ
／４ＧＨ方式の反射型液晶表示装置を用いてドットマト
リクス型の表示装置を構成しようとした場合、以下のよ
うな問題点があった。１つは液晶層５０はその明暗で表
示画像を形成するが、観測者には同じ像が反射層２０に
映ってみえるため像がだぶり視認性を低下させる。また
画素ピッチが小さくなるにしたがって、コントラストが
低下するという問題がある。この原因は、液晶層５０と
反射板２０とが隔たっているために、明表示部を通った
光線が隣接する暗表示部に入射したり、暗表示部を通っ
た光線が隣接する明表示部を透過したりすることに起因
する。すなわち反射板２０での反射の前後で、表示状態
の異なる画素を通過するため、前記の作用が働かずコン
トラスト低下が生じる。この現象は画素の一辺の長さ
が、液晶層５０と反射板２０との距離と同程度か、それ
より小さくなると顕著に現れる。すなわち高精細化が進
むほど問題は顕著になり、とくに支持面に斜め方向から
表示を観察した場合に顕著に観察される。However, such a λ
When a dot matrix type display device is constructed by using the / 4GH type reflection type liquid crystal display device, there are the following problems. First, the liquid crystal layer 50 forms a display image with its lightness and darkness, but the same image appears to the observer on the reflective layer 20, so that the image is faded and the visibility is lowered. There is also a problem that the contrast decreases as the pixel pitch decreases. This is because the liquid crystal layer 50 and the reflection plate 20 are separated from each other, so that a light ray passing through the bright display portion is incident on an adjacent dark display portion, or a light ray passing through the dark display portion is adjacent to the bright display portion. Due to the penetration of. That is, before and after the reflection by the reflection plate 20, the light passes through pixels having different display states, so that the above action does not work and the contrast is lowered. This phenomenon remarkably appears when the length of one side of the pixel is about the same as or smaller than the distance between the liquid crystal layer 50 and the reflection plate 20. That is, the problem becomes more remarkable as the definition becomes higher, and particularly when the display is observed obliquely on the supporting surface.
【０００６】さらに、アクティブマトリクス方式の構成
にした場合に表示が暗いという問題があった。λ／４Ｇ
Ｈ方式の液晶表示装置は電圧−反射率特性の立ち上がり
が緩慢なため、単純マトリクス方式の構成では走査線本
数が多くなった場合に十分なコントラストをとることが
できない。走査線本数を多くしてもコントラストの低下
を招かない表示方法として、１画素１画素に能動素子を
設けるアクティブマトリクス方式が知られている。例え
ば能動素子として薄膜トランジスタ（以下「ＴＦＴ」と
いう）を用いたアクティブマトリクス方式では、画素と
なる電極（画素電極という）以外に、走査電極、データ
電極、ＴＦＴ、蓄積容量などを支持板上に形成する。こ
のため全面積に占める画素電極面積の割合である開口率
は高々４０％に過ぎない。従来のλ／４ＧＨ方式におい
て支持板１２をアクティブマトリクス基板とした場合、
外部から入射した光はＴＦＴが形成された支持板１２を
通り、反射板２０で反射した後、再度支持板１２を透過
する。すなわち支持板１２を２回透過するため、液晶表
示装置の平均反射率は開口率の二乗に比例する。前述の
ごとく開口率は高々４０％に過ぎないので、液晶表示装
置の平均反射率は１６％（＝０．４2）を越えることは
なく、極めて暗く視認性の低い表示となっていた。そこ
で本発明はかかる従来のλ／４ＧＨ方式の反射型液晶表
示装置の問題を解決し、高精細化してもコントラストが
高く、像のだぶりがなく、またアクティブマトリクス方
式の場合の平均反射率低下を防止したλ／４ＧＨ方式の
反射型液晶表示装置を提供することを目的とする。Further, there is a problem that the display is dark when the active matrix system is used. λ / 4G
Since the H-type liquid crystal display device has a slow rise in voltage-reflectance characteristics, a simple matrix system configuration cannot provide sufficient contrast when the number of scanning lines is large. As a display method in which the contrast is not deteriorated even if the number of scanning lines is increased, an active matrix method in which an active element is provided in each pixel is known. For example, in an active matrix method using a thin film transistor (hereinafter referred to as “TFT”) as an active element, a scanning electrode, a data electrode, a TFT, a storage capacitor, etc. are formed on a support plate in addition to an electrode serving as a pixel (referred to as a pixel electrode). . Therefore, the aperture ratio, which is the ratio of the pixel electrode area to the entire area, is no more than 40%. When the support plate 12 is an active matrix substrate in the conventional λ / 4GH system,
Light incident from the outside passes through the support plate 12 on which the TFT is formed, is reflected by the reflection plate 20, and then passes through the support plate 12 again. That is, since the light is transmitted through the support plate 12 twice, the average reflectance of the liquid crystal display device is proportional to the square of the aperture ratio. As described above, since the aperture ratio is only 40% at most, the average reflectance of the liquid crystal display device does not exceed 16% (= 0.4 2 ) and the display is extremely dark and has low visibility. Therefore, the present invention solves the problems of the conventional reflection type liquid crystal display device of the λ / 4GH system, has a high contrast even if the resolution is increased, there is no image blurring, and a decrease in the average reflectance in the case of the active matrix system. An object of the present invention is to provide a λ / 4GH type reflection type liquid crystal display device which is prevented.
【０００７】[0007]
【課題を解決するための手段】本発明は、電極を有する
２枚の支持板と、前記支持板間に挟まれた２色性色素を
含む液晶層と、この液晶層に入射した光を反射する反射
板と、前記反射板と前記液晶層との間に設けられた位相
差板とを有する反射型液晶表示装置において、前記２枚
の支持板の一方の電極を前記反射板に兼用するととも
に、この反射板とする電極と前記液晶層との間に前記位
相差板を配置したことを特徴とする。According to the present invention, two supporting plates having electrodes, a liquid crystal layer containing a dichroic dye sandwiched between the supporting plates, and light incident on the liquid crystal layer are reflected. In a reflection type liquid crystal display device having a reflection plate for controlling and a retardation plate provided between the reflection plate and the liquid crystal layer, one electrode of the two support plates is also used as the reflection plate. The retardation plate is arranged between the electrode serving as the reflection plate and the liquid crystal layer.
【０００８】[0008]
【作用】本発明においては、２枚の支持板の一方の電極
を前記反射板に兼用するとともに、この反射板とする電
極と前記液晶層との間に前記位相差板を配置したため、
液晶層と反射板とを近接して配置することができ、この
ため液晶層による表示像のコントラスト低下とだぶりを
抑えることができる。In the present invention, one electrode of the two support plates is also used as the reflection plate, and the retardation plate is arranged between the electrode serving as the reflection plate and the liquid crystal layer.
The liquid crystal layer and the reflection plate can be arranged in close proximity to each other, so that the reduction in the contrast of the display image and the dullness due to the liquid crystal layer can be suppressed.
【０００９】[0009]
【実施例】以下、実施例に基づいて、本発明を具体的に
説明する。 （実施例１）図１は本発明の第１の実施例を示す斜視図
である。この実施例の反射型液晶表示装置は、透光性電
極２１、配向膜４１が順次形成された支持板１１と、電
極２３、配向膜４３、位相差板３０、配向膜４２が順次
形成された支持板１２と、これらの間に挟まれた液晶層
５０とから構成される。支持板１１，１２には、ほう珪
酸ガラス、石英ガラスなどのガラスや、ポリアクリル、
ポリエチレンテレフタレート、ポリカーボネートなどの
透光性樹脂など、透光性と機械強度と表面平坦性を有す
る材料から選ぶことができる。この反射型液晶表示装置
は次のように作成される。まず支持板１１上に、ＳｎＯ
2やＩＴＯ（Ｉｎｄｉｕｍ Ｔｉｎ Ｏｘｉｄｅ）など
の透光性導電材料を、蒸着法やスパッタリング法によっ
て成膜したのち、フォトエッチング法にて所望の形状に
パターニングして電極２１を形成する。電極２１上にポ
リイミドなどの配向材料よりなる配向膜４１を形成、ラ
ビング処理する。EXAMPLES The present invention will be specifically described below based on examples. (Embodiment 1) FIG. 1 is a perspective view showing a first embodiment of the present invention. In the reflection type liquid crystal display device of this embodiment, the support plate 11 on which the translucent electrode 21 and the alignment film 41 are sequentially formed, and the electrode 23, the alignment film 43, the retardation film 30 and the alignment film 42 are sequentially formed. It is composed of the support plate 12 and the liquid crystal layer 50 sandwiched between them. The support plates 11 and 12 include glass such as borosilicate glass and quartz glass, polyacryl,
The material can be selected from materials having a light-transmitting property, mechanical strength, and surface flatness, such as a light-transmitting resin such as polyethylene terephthalate and polycarbonate. This reflective liquid crystal display device is manufactured as follows. First, on the support plate 11, SnO
A transparent conductive material such as 2 or ITO (Indium Tin Oxide) is formed into a film by a vapor deposition method or a sputtering method, and then patterned into a desired shape by a photo etching method to form an electrode 21. An alignment film 41 made of an alignment material such as polyimide is formed on the electrode 21 and subjected to rubbing treatment.
【００１０】一方、Ａｌ、Ａｇ、Ｃｒなど高反射率な金
属を、鏡面となる条件下で、蒸着法、スパッタリング法
などの方法を用いて支持板１２上に成膜する。一般に低
温、高成膜速度、薄膜厚に成膜するほど鏡面を得易い。
次にこれを所望の形状にパターニングして電極２３を形
成する。電極２３の厚みは、外光を完全に反射し、かつ
十分低電気抵抗となる範囲で選ばれ、通常０．１〜２．
０μｍの範囲で好適に使用される。支持板１２上に電極
２３を形成した後、液晶性高分子よりなる位相差板３０
を形成する。このためまず電極２３上にポリイミドなど
の配向材料よりなる配向膜４３を形成、ラビング処理す
る。次に液晶性高分子としてｐｏｌｙ−６ＣＢＡ（化
１）をシクロヘキサノンに２０ｗｔ％溶解して前記配向
膜上にスピン塗布した。これを溶媒乾燥し、等方相まで
昇温したのち、徐冷して位相差板３０を得た。On the other hand, a high-reflectance metal such as Al, Ag, and Cr is formed on the support plate 12 by a method such as a vapor deposition method or a sputtering method under the condition of forming a mirror surface. Generally, the lower the temperature, the higher the deposition rate, and the more thinly the film is deposited, the easier it is to obtain a mirror surface.
Next, this is patterned into a desired shape to form the electrode 23. The thickness of the electrode 23 is selected within a range that completely reflects outside light and has a sufficiently low electric resistance, and is usually 0.1 to 2.
It is preferably used in the range of 0 μm. After forming the electrode 23 on the support plate 12, a retardation plate 30 made of a liquid crystalline polymer is formed.
To form. Therefore, first, an alignment film 43 made of an alignment material such as polyimide is formed on the electrode 23 and subjected to a rubbing process. Next, 20 wt% of poly-6CBA (Chemical formula 1) as a liquid crystalline polymer was dissolved in cyclohexanone and spin-coated on the alignment film. This was dried with a solvent, heated to an isotropic phase, and then gradually cooled to obtain a retardation plate 30.
【００１１】[0011]
【化１】 [Chemical 1]
【００１２】液晶性高分子の材料としては前記のｐｏｌ
ｙ−６ＣＢＡ以外に、ポリアクリレート、ポリメタクリ
レート、ポリシロキサンなどの側鎖型液晶性高分子や、
ポリエステル、ポリアミド、ポリカーボネート、ポリエ
ステルイミドなどの主鎖型液晶性高分子が利用できる。
モノドメイン配向を得るためには、前記液晶性高分子
が、ある温度範囲で液晶性を示すサーモトロピック液晶
であり、かつ液晶相より低温側の温度でガラス相に相転
移して配向状態を凍結できる必要がある。ｐｏｌｙ−６
ＣＢＡの複屈折は０．２３であったので、５５０ｎｍの
可視光に対して１／４波長となるように、厚みを０．６
０μｍに設定した。位相差板３０上にポリビニルブチラ
ールの５ｗｔ％エチルセロソルブ溶液をスピン塗布、溶
媒乾燥した後、位相差板３０の液晶性高分子の配向方向
と４５°をなす方向にラビング処理して配向膜４２を形
成した。このようにして準備した支持板１１と支持板１
２とを、液晶層５０がホモジニアス配向するように貼り
合わせ液晶セルを作製した。液晶層５０には２色性色素
を含むネマチック液晶を用いた。２色性色素としてアゾ
系色素を主成分とする黒色２色性色素（三井東圧化学
（株）製，Ｓ−３４４）１．４ｗｔ％を、ホストのフェ
ニルシクロヘキサン系ネマチック液晶（Ｅ．Ｍｅｒｃｋ
（株）製，ＺＬＩ−１８４０）に添加した。As the liquid crystalline polymer material, the above-mentioned pol is used.
In addition to y-6CBA, side chain type liquid crystalline polymers such as polyacrylate, polymethacrylate, and polysiloxane,
Main chain type liquid crystalline polymers such as polyester, polyamide, polycarbonate and polyester imide can be used.
In order to obtain monodomain alignment, the liquid crystalline polymer is a thermotropic liquid crystal that exhibits liquid crystallinity in a certain temperature range, and the alignment state is frozen by phase transition to a glass phase at a temperature lower than the liquid crystal phase. You need to be able to. poly-6
Since the birefringence of CBA was 0.23, the thickness was 0.6 so that the wavelength was ¼ wavelength with respect to visible light of 550 nm.
It was set to 0 μm. A 5 wt% ethyl cellosolve solution of polyvinyl butyral is spin-coated on the retardation plate 30 and solvent-dried, and then a rubbing treatment is performed in a direction forming an angle of 45 ° with the orientation direction of the liquid crystal polymer of the retardation plate 30 to form an alignment film 42. Formed. The support plate 11 and the support plate 1 thus prepared
And No. 2 were laminated so that the liquid crystal layer 50 would be homogeneously aligned to prepare a liquid crystal cell. A nematic liquid crystal containing a dichroic dye was used for the liquid crystal layer 50. 1.4% by weight of a black dichroic dye (S-344, manufactured by Mitsui Toatsu Chemicals, Inc.) containing an azo dye as a main component as a dichroic dye was used as a host phenylcyclohexane nematic liquid crystal (E. Merck).
ZLI-1840 manufactured by Co., Ltd.) was added.
【００１３】（実施例２）図２は本発明の第２の実施例
を示す斜視図である。支持板１１上に光散乱層７０を形
成した点が実施例１と異なる。光散乱層７０は以下のよ
うにして準備した。亜鉛華１ｇと、樹脂濃度１５％のア
クリル樹脂溶液（日本合成ゴム（株）オプトマーＳＳ１
１５１Ｅ）１０ｇと、直径１ｍｍのガラスビーズ適量と
を混合し、密封容器に収めた後、サンプルシェーカーで
１時間混錬した。ガラスビーズを除去後、この分散液を
支持板１１上に滴下し、２０００ｒｐｍ，５秒間スピン
コートしたのち、オーブン中で１８０°Ｃ，１時間、熱
処理して光散乱層７０を得た。以下、実施例１と同様に
して反射型液晶表示装置を構成した。亜鉛華の代わりに
他の白色顔料も利用できるが、光散乱層７０を通して液
晶層５０を観察するため、光散乱層７０は後方散乱が小
さく、前方散乱が大きな材料が好ましい。本実施例によ
れば、光散乱層７０の働きにより、外界の映りこみを排
することができ、表示品質をより向上させることができ
る。(Embodiment 2) FIG. 2 is a perspective view showing a second embodiment of the present invention. The difference from Example 1 is that the light scattering layer 70 is formed on the support plate 11. The light scattering layer 70 was prepared as follows. 1 g of zinc white and acrylic resin solution with a resin concentration of 15% (Japan Synthetic Rubber Co., Ltd. Optomer SS1
151E) 10 g and an appropriate amount of glass beads having a diameter of 1 mm were mixed, placed in a sealed container, and then kneaded with a sample shaker for 1 hour. After removing the glass beads, this dispersion was dropped on the support plate 11, spin-coated at 2000 rpm for 5 seconds, and then heat-treated at 180 ° C. for 1 hour in an oven to obtain a light-scattering layer 70. Hereinafter, a reflective liquid crystal display device was constructed in the same manner as in Example 1. Other white pigments can be used instead of zinc white, but since the liquid crystal layer 50 is observed through the light scattering layer 70, the light scattering layer 70 is preferably made of a material having a small backscattering and a large forward scattering. According to the present embodiment, due to the function of the light scattering layer 70, the reflection of the outside world can be eliminated, and the display quality can be further improved.
【００１４】（実施例３）図３は本発明の第３の実施例
を示す斜視図である。電極２３上に凹凸を設けた点が実
施例１と異なる。このような電極は、支持板１２に擦り
ガラスを用いてその凹凸上にＡｌ，Ａｇなど高反射率の
金属を蒸着する方法、支持板１２をフォトエッチングに
より凹凸に加工しその凹凸上にＡｌ，Ａｇなど高反射率
の金属を蒸着する方法、蒸着した金属膜をフォトエッチ
ングして凹凸を形成する方法などが利用できる。凹凸の
サイズが可視光の波長に対して小さすぎると、偏光解消
が生じてコントラストが低下するので、可視光の波長よ
り十分に大きい必要がある。また表示の均一性を確保す
る観点から、画素サイズより十分に小さくなくてはなら
ない。このことから凹凸のサイズは１〜５０μｍの範
囲、より好ましくは１〜１０μｍの範囲が好適に使用さ
れる。また明るい外観を得るためには、凹凸の平均斜度
を５〜１０°にする必要がある。(Embodiment 3) FIG. 3 is a perspective view showing a third embodiment of the present invention. The difference from Example 1 is that unevenness is provided on the electrode 23. For such an electrode, a method of depositing a metal having a high reflectance such as Al or Ag on the unevenness by using frosted glass for the support plate 12, or processing the support plate 12 into the unevenness by photoetching, and forming Al on the unevenness, A method of vapor-depositing a metal having a high reflectance such as Ag, a method of photo-etching the vapor-deposited metal film to form irregularities, and the like can be used. If the size of the unevenness is too small with respect to the wavelength of visible light, depolarization occurs and the contrast decreases, so it is necessary to be sufficiently larger than the wavelength of visible light. Also, from the viewpoint of ensuring display uniformity, it must be sufficiently smaller than the pixel size. From this, the size of the irregularities is preferably in the range of 1 to 50 μm, more preferably 1 to 10 μm. Further, in order to obtain a bright appearance, it is necessary to set the average inclination of the unevenness to 5 to 10 °.
【００１５】（実施例４）図４は能動素子に薄膜トラジ
スタを用いた本発明の第４の実施例を示す断面図であ
る。以下、製造方法に従って本実施例を説明する。まず
ガラスよりなる支持板１２上に、Ｃｒ，Ａｌ，Ｔａ，Ｍ
ｏなどの金属材料よりなる走査電極を形成する。これら
の金属材料はスパッタリング法によって成膜され、つぎ
にフォトエッチング法により所望の形状にパターニング
される。走査電極上にＳｉＯ2，ＳｉＮｘなどのゲート
絶縁膜、アモルファスＳｉよりなる半導体膜、ゲート絶
縁膜と同様の材料よりなる上部絶縁膜を、プラズマ化学
気相成長法にて連続的に成膜する。絶縁耐圧向上のため
に、走査電極上部を陽極酸化してあらかじめ絶縁膜を形
成した後に、前記絶縁膜を成膜してゲート絶縁膜を２層
構造としてもよい。上部絶縁膜をパターニングしたの
ち、Ｐなどの不純物を添加したアモルファスＳｉなどの
ｎ+半導体膜を成膜し、前記ｎ+半導体膜と前記半導体膜
とを同時にパターニングする。(Embodiment 4) FIG. 4 is a sectional view showing a fourth embodiment of the present invention in which a thin film transistor is used as an active element. Hereinafter, this embodiment will be described according to the manufacturing method. First, Cr, Al, Ta, M is placed on the support plate 12 made of glass.
A scan electrode made of a metal material such as o is formed. These metal materials are formed into a film by a sputtering method and then patterned into a desired shape by a photo etching method. A gate insulating film made of SiO 2 , SiNx or the like, a semiconductor film made of amorphous Si, and an upper insulating film made of the same material as the gate insulating film are continuously formed on the scanning electrodes by plasma enhanced chemical vapor deposition. In order to improve the withstand voltage, the upper part of the scanning electrode may be anodized to form an insulating film in advance, and then the insulating film may be formed to have a two-layer structure of the gate insulating film. After patterning the upper insulating film, an n + semiconductor film such as amorphous Si doped with an impurity such as P is formed, and the n + semiconductor film and the semiconductor film are simultaneously patterned.
【００１６】次にＳｉＯ2，ＳｉＮｘ，ポリイミドなど
よりなる第一層間絶縁膜を形成し、その上にＡｌなどの
低抵抗金属よりなるデータ電極を配線する。この時同時
に画素電極２３を形成してもよいが、Ａｌ，Ｃｒ，Ａ
ｇ，Ｐｔなど高反射率金属を用いて別途、画素電極２３
を形成してもよい。上記の手順で能動素子６０を形成し
た支持板１２上に配向膜４３、位相差板３０、配向膜４
２を形成する。また支持板１１上に光散乱層７０、電極
２１、配向膜４１を形成し、実施例２と同様にλ／４Ｇ
Ｈ方式の液晶表示装置の構成とした。本実施例の構成の
よれば、外光が支持板１２を２回透過することによる平
均反射率の低下を防止できるため、従来のλ／４ＧＨ方
式を用いたものと比較して明るい表示を得ることができ
た。この実施例では、能動素子をＴＦＴとしたが、能動
素子にダイオード、ＭＩＭ、バリスタ等を用いた場合に
も同様に適用できる。またＴＦＴの構造として、逆スタ
ガ型の構造と製法を例示したが、正スタガ型、プレーナ
型の場合にも本発明の効果は同様に有効である。Next, a first interlayer insulating film made of SiO 2 , SiNx, polyimide or the like is formed, and a data electrode made of a low resistance metal such as Al is wired thereon. At this time, the pixel electrodes 23 may be formed simultaneously, but Al, Cr, A
The pixel electrode 23 is separately formed by using a high-reflectance metal such as g or Pt.
May be formed. The alignment film 43, the retardation film 30, and the alignment film 4 are formed on the support plate 12 on which the active element 60 is formed by the above procedure.
Form 2. Further, the light scattering layer 70, the electrode 21, and the alignment film 41 are formed on the support plate 11, and λ / 4G is formed as in the second embodiment.
An H-type liquid crystal display device is used. According to the configuration of the present embodiment, it is possible to prevent a decrease in the average reflectance due to the external light being transmitted through the support plate 12 twice, so that a brighter display can be obtained as compared with the one using the conventional λ / 4GH method. I was able to. In this embodiment, the active element is the TFT, but the same can be applied to the case where a diode, MIM, varistor or the like is used as the active element. Further, as the structure of the TFT, the reverse stagger type structure and the manufacturing method are exemplified, but the effects of the present invention are similarly effective in the case of the positive stagger type and the planar type.
【００１７】[0017]
【発明の効果】本発明によれば、高精細化してもコント
ラストが高く、像のだぶりがない反射型液晶表示装置を
提供できる。またアクティブマトリクス方式と組み合せ
ることによって、高コントラスト化、大表示容量化が可
能となる。According to the present invention, it is possible to provide a reflection type liquid crystal display device which has a high contrast and has no image blurring even if the resolution is increased. Further, by combining with the active matrix system, it is possible to realize high contrast and large display capacity.
【図１】本発明の第１の実施例を示す斜視図である。FIG. 1 is a perspective view showing a first embodiment of the present invention.
【図２】本発明の第２の実施例を示す斜視図である。FIG. 2 is a perspective view showing a second embodiment of the present invention.
【図３】本発明の第３の実施例を示す斜視図である。FIG. 3 is a perspective view showing a third embodiment of the present invention.
【図４】アクティブマトリクス方式を用いた本発明の第
４の実施例を示す断面図である。FIG. 4 is a sectional view showing a fourth embodiment of the present invention using an active matrix system.
【図５】従来技術の構成を示す斜視図である。FIG. 5 is a perspective view showing a configuration of a conventional technique.
１ 液晶セル １１，１２ 支持板 ２０ 反射板 ２１，２２ 電極 ２３ 反射板を兼ねた電極 ３０ 位相差板 ４１，４２ 配向膜 ５０ 液晶層 ６０ 能動素子 ７０ 光拡散板 １０１ 位相差板の光学軸の方向 １０２ 配向膜４２のラビング方向 １０３ 配向膜４１のラビング方向 １０５ 電極２２上に形成された凹凸 DESCRIPTION OF SYMBOLS 1 Liquid crystal cell 11,12 Support plate 20 Reflective plate 21,22 Electrode 23 Electrode also serving as a reflective plate 30 Phase difference plate 41,42 Alignment film 50 Liquid crystal layer 60 Active element 70 Light diffusion plate 101 Direction of optical axis of phase difference plate 102 rubbing direction of alignment film 42 103 rubbing direction of alignment film 41 105 unevenness formed on the electrode 22
Claims (1)
板間に挟まれた２色性色素を含む液晶層と、この液晶層
に入射した光を反射する反射板と、前記反射板と前記液
晶層との間に設けられた位相差板とを有する反射型液晶
表示装置において、前記２枚の支持板の一方の電極を前
記反射板に兼用するとともに、この反射板とする電極と
前記液晶層との間に前記位相差板を配置したことを特徴
とする反射型液晶表示装置。1. A support plate having two electrodes, a liquid crystal layer containing a dichroic dye sandwiched between the support plates, a reflection plate for reflecting light incident on the liquid crystal layer, and the reflection plate. And a retardation plate provided between the liquid crystal layer and the liquid crystal layer. In the reflection type liquid crystal display device, one electrode of the two support plates is also used as the reflection plate, and an electrode serving as the reflection plate is used. A reflective liquid crystal display device, wherein the retardation plate is disposed between the liquid crystal layer and the liquid crystal layer.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6145337A JPH07333600A (en) | 1994-06-03 | 1994-06-03 | Reflection type liquid crystal display device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6145337A JPH07333600A (en) | 1994-06-03 | 1994-06-03 | Reflection type liquid crystal display device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH07333600A true JPH07333600A (en) | 1995-12-22 |
Family
ID=15382847
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6145337A Pending JPH07333600A (en) | 1994-06-03 | 1994-06-03 | Reflection type liquid crystal display device |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH07333600A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0737882A3 (en) * | 1995-04-11 | 1997-04-23 | Sony Corp | Reflective host-receiver display device |
| US5798809A (en) * | 1996-08-16 | 1998-08-25 | Fujitsu Limited | Liquid crystal display panel |
| JP2012128000A (en) * | 2010-12-13 | 2012-07-05 | Japan Display Central Co Ltd | Liquid crystal display device |
-
1994
- 1994-06-03 JP JP6145337A patent/JPH07333600A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0737882A3 (en) * | 1995-04-11 | 1997-04-23 | Sony Corp | Reflective host-receiver display device |
| US5798809A (en) * | 1996-08-16 | 1998-08-25 | Fujitsu Limited | Liquid crystal display panel |
| JP2012128000A (en) * | 2010-12-13 | 2012-07-05 | Japan Display Central Co Ltd | Liquid crystal display device |
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