JP4048721B2 - Dispersion medium - Google Patents

Description

【００１０】
式中、Ａ１〜Ａ６は、ベンゼン環、シクロヘキサン環、ジオキサン環、ピリミジン環、フラン環、テトラヒドロフラン環、ジチアン環、ピペリジン環、ピレラジン環、モーホリン環、シクロペンタン環、シクロブタン環、ピリジン環、チオフェン環、ピロール環、またはシクロヘキセン環であり、
Ｘ１〜Ｘ４，Ｙ１〜Ｙ３，Ｚは、１個または複数個の置換基（水素、フッ素、塩素、臭素、ヨウ素、シアノ基、ニトロ基、アミノ基、ヒドロキシル基、アルカノイルオキシ基、アルコキシカルボニル基、カルボキシ基、トリフルオロメチル基、トリフルオロメトキシ基、アルコキシメチレン基、アルキル基、アルコキシ基、アルケニル基、アルキニル基、スルホン酸基、チオアルキル基、モノ、ジ、またはトリアルキルアミノ基）を示し、
Ｂ１〜Ｂ４は、なし（環同士の単結合）か、ＣＯＯ、ＯＣＯ、ＣＨ＝Ｎ、Ｎ＝ＣＨ、ＣＨ＝ＣＨ、（ＣＨ₂)_n Ｏ、Ｏ（ＣＨ₂)_n 、（ＣＨ₂)_n 、Ｏ（ＣＨ₂)_n Ｏ、ＣＨ＝ＣＨ−ＣＯＯ、ＯＣＯ−ＣＨ＝ＣＨ、Ｏ、ＣＯ、ＮＨＣＯ、ＣＯＮＨ、Ｎ＝Ｎ、Ｎ₂ Ｏ、Ｃ≡Ｃ、ＳＯ、ＳＯ₂ 、またはＮＨを示し（ｎは１〜１０の整数）、
Ｃ１，Ｃ２は、ナフタレン、テトラヒドロナフタレン、デカヒドロナフタレン、インデン、キノリン、クマリン、アズレン、フルオレン、ジヒドロフェナントレンを示す。
【００１１】
（１）〜（４）の構造式の具体例としては、下記の（５）〜（３２）が挙げられる。
【００１２】
【化３】

【００１３】
【化４】

【００１４】
【化５】

【００１５】
【化６】

【００１６】
【化７】

【００１７】
上記構造式において、Ｒ1 〜Ｒ33およびＸ，Ｙは以下の通りである。
Ｒ1 〜Ｒ33：アルキル基、アルコキシ基、アルコキシメチレン基、ハロゲン元素、水素、アルケニル基、アルキニル基、シアノ基、ニトロ基、アミノ基、ヒドロキシル基、アルカノイルオキシ基、アルコキシカルボニル基、トリフルオロメチル基、カルボキシ基、モノアルキルアミノ基、ジアルキルアミノ基、トリアルキルアミノ基、スルホン酸基、チオアルキル基、トリフルオロメトキシ基、アシル基、アシルオキシ基、ホルミル基、
Ｘ，Ｙ：なし（環同士の単結合）、ＣＯＯ、ＯＣＯ、ＣＨ＝Ｎ、Ｎ＝ＣＨ、ＣＨ＝ＣＨ、（ＣＨ₂)_n Ｏ、Ｏ（ＣＨ₂)_n 、（ＣＨ₂)_n 、Ｏ（ＣＨ₂)_n Ｏ、ＣＨ＝ＣＨ−ＣＯＯ、ＯＣＯ−ＣＨ＝ＣＨ、Ｏ、ＣＯ、ＮＨＣＯ、ＣＯＮＨ、Ｎ＝Ｎ、Ｎ₂ Ｏ、Ｃ≡Ｃ、ＳＯ、ＳＯ₂ 、ＮＨ。なお、ｎは１〜１０の整数。
【００１８】
これらの有機化合物のうち、光学的異方性の小さいものを使用することが好ましい。分散媒として光学的異方性の大きな有機化合物を使用すると、分子の配向に依存した散乱や複屈折や旋光性が生じ易いため、光の均一性を低下させる要因となる。光学的異方性の小さいもの、特に、光学的に等方性であるものを使用することにより、電気泳動表示装置の各画素から生じる光の均一性を良好にすることができ、視野角を広くすることができる。
【００１９】
前記（１）〜（４）のいずれかの構造式で表される有機化合物であって、光学的異方性の小さいものとしては、シクロヘキシルシクロヘキサン系、フェニルシクロヘキサン系、フェニルエチルシクロヘキサン系、フェニルシクロヘキサンカルボキシラート系、４−フェニル−１，３−ジオキサン系、２−フェニルエチル−１，３−ジオキサン系等が挙げられる。
【００２０】
本発明は、電極間の領域を画素毎にセルで区分し、各セルの内部でのみ電気泳動粒子の移動を許容するようにしてある構造の電気泳動表示装置に、好適に適用される。
【００２１】
【発明の実施の形態】
以下、本発明の実施形態について説明する。
この実施形態の電気泳動表示装置は、電気泳動表示パネルと周辺回路とを備えているが、本発明の特徴は電気泳動表示パネルを構成する分散液にあるため、周辺回路についての説明は省略する。図１および２を用いてこの実施形態の電気泳動表示パネルを説明する。
【００２２】
この表示パネルＡは、素子基板１００と、これに対向配置された対向基板２００と、両基板の間に配置されたセル部１１とを備えている。図１は、対向基板２００を外して上側に持ち上げた状態を示す斜視図であり、図２は部分断面図である。
対向基板２００の素子基板１００との対向面には共通電極２０１が形成され、その上に封止層２０２が形成されている。対向基板２００、共通電極２０１、および封止層２０２は全て透明であり、この対向基板２００側が表示パネルＡの表面（観察面）となっている。
【００２３】
素子基板１００の対向基板２００との対向面の中央部（表示領域１００Ａ）には、画素電極１０４、走査線、データ線１０２、およびスイッチング素子として機能する薄膜トランジスタが形成されている。表示領域１００Ａの外側の周辺領域１００Ｂには、走査線駆動回路、データ線駆動回路１４０、および外部接続電極が形成されている。
【００２４】
また、表示領域１００Ａの上に、隔壁１１０が一定高さで格子状に組まれた形状のセル部１１が形成されている。このセル部１１は、例えば、素子基板１００上への感光性ポリイミド前駆体からなる塗膜の形成工程、セルパターンに対応させたマスクを介した紫外線照射工程、および現像工程を、順次行うことによって形成される。
【００２５】
このセル部１１の隔壁１１０で囲われた部分が、電極間（共通電極２０１と画素電極１０４との間）の領域を画素毎に区分するセル１１Ｃとなっている。全てのセル１１Ｃ内に、分散媒２に電気泳動粒子３を分散させた分散液１が充填されている。分散媒２には必要に応じて界面活性剤等の添加剤が添加されている。
ここで、この表示パネルＡはフルカラー表示体であるため、３個の隣接するセル１１Ｃを一組とし、各組の３つのセル１１Ｃに、それぞれＲ（赤）、Ｇ（緑）、Ｂ（青）に対応させた分散液を充填している。各色用の分散液では、表示色と同じ色の電気泳動粒子を用い、表示色を吸収する色（例えば補色）となるように分散媒を染色してある。
【００２６】
具体的に、Ｒ用の分散液では、電気泳動粒子３として赤色粒子（例えば酸化鉄粒子）を用い、分散媒をシアン色の染料で染色する。Ｇ用の分散液では、電気泳動粒子３として緑色粒子（例えばコバルトグリーンの顔料粒子）を用い、分散媒をマゼンダ色の染料で染色する。Ｂ用の分散液では、電気泳動粒子３として青色粒子（例えばコバルトブルーの顔料粒子）を用い、分散媒をイエロー色の染料で染色する。
【００２７】
これにより、電気泳動粒子３が表面（観察面）側の電極（共通電極２０１）に引き付けられているときには、対向基板２００を透過して分散液１に入射された光は電気泳動粒子３で反射するため、表示色に対応する波長の光が放射されて、観察面から表示色が見える。電気泳動粒子３が素子基板１００側の電極（画素電極１０４）に引き付けられているときには、対向基板２００を透過して分散液１に入射された光は電気泳動粒子３で反射するが、この反射光（表示色に対応する波長の光）が分散媒によって吸収されるため、観察面から表示色は見えない。
【００２８】
ここで、分散液１に印加する電界強度によって、電気泳動粒子３の両電極間での位置および分布状態を制御することができる。そのため、各色のセル毎に分散液１に印加する電界強度を制御して、各色のセルでの電気泳動粒子３の位置および分布状態を制御することにより、各組のカラー画素を所望の色に調整できるため、この表示パネルＡによってフルカラーによる画像が表示できる。
【００２９】
また、この実施形態では、分散媒２として、下記の表１〜７に示す実施例１〜１９の組成のものを使用する。
【００３０】
【表１】

【００３１】
【表２】

【００３２】
【表３】

【００３３】
【表４】

【００３４】
【表５】

【００３５】
【表６】

【００３６】
【表７】

【００３７】
これらの組成の分散媒は、ドデシルベンゼン等の環を一つしか含まない構造式の有機化合物のみからなる分散媒と比較して、低粘度でありながら蒸発し難く、封止材に染み込み難い。そのため、ドデシルベンゼンのみからなる分散媒を使用した場合よりも、電気泳動表示装置の信頼性および応答スピードが高くなる。
【００３８】
【発明の効果】
以上説明したように、本発明によれば、電気泳動表示装置の信頼性および応答スピードを高くすることができる。
【図面の簡単な説明】
【図１】本発明の一実施形態に相当する電気泳動表示装置を構成する電気泳動表示パネルを示す斜視図であって、対向基板を外して上側に持ち上げた状態を示す。
【図２】図１の電気泳動表示パネルの部分断面図である。
【符号の説明】
１ 分散液
２ 分散媒
３ 電気泳動粒子
１１ セル部
１１Ｃ セル
１００ 素子基板
１００Ａ 表示領域
１００Ｂ 周辺領域
１０２ データ線
１０４ 画素電極
１１０ 隔壁
１４０ データ線駆動回路
２００ 対向基板
２０１ 共通電極
２０２ 封止層
Ａ 表示パネル[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electrophoretic display device.
[0002]
[Prior art]
An electrophoretic display device using an electrophoretic phenomenon is known as a non-luminous display device. The electrophoresis phenomenon is a phenomenon in which particles (electrophoretic particles) that are naturally charged by dispersion migrate by Coulomb force when an electric field is applied to a dispersion liquid in which fine particles are dispersed in a liquid (dispersion medium).
[0003]
In the basic structure of the electrophoretic display device, one electrode and the other electrode are opposed to each other at a predetermined interval, and a dispersion liquid is sealed therebetween. When a potential difference is applied between the two electrodes, the electrophoretic particles are attracted to one of the electrodes depending on the direction of the electric field. Therefore, if the dispersion medium is dyed with a dye and the electrophoretic particles are composed of pigment particles in this structure, the color of the electrophoretic particles or the color of the dye can be seen from the observation surface on which the transparent substrate and the transparent electrode are arranged. .
[0004]
Therefore, in the electrophoretic display device having this configuration, an image can be displayed by forming electrodes in a pattern corresponding to each pixel and controlling the voltage applied to each pixel electrode.
As a dispersion medium for such an electrophoretic display device, for example, in an article by an engineer of NOK Corporation "Electrophoretic display using microcapsules" (Japan Hardcopy '99 papers 237-240), etc. The use of benzene is described. In this paper, it is described that the dispersion is not encapsulated directly between the electrodes but placed in a microcapsule.
[0005]
On the other hand, Japanese Examined Patent Publication No. SHO 49-32038 discloses an electrophoretic display device in which a cell for dividing a dispersion liquid for each pixel is provided between electrodes, and movement of electrophoretic particles is allowed only within each cell. Has been. By providing this cell, the resolution of the image of the electrophoretic display device can be increased, and colorization can be easily handled.
[0006]
[Problems to be solved by the invention]
However, when dodecylbenzene is used as the dispersion medium of the electrophoretic display device, there is room for improvement in terms of reliability and response speed. As for reliability, there is a possibility that the sealant or sealant used for sealing the dispersion is corroded by dodecylbenzene, resulting in incomplete sealing of the dispersion.
[0007]
An object of the present invention is to improve the reliability and response speed of an electrophoretic display device by specifying a dispersion medium.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention provides an electrophoretic display device characterized in that an organic compound containing two or more rings in a structural formula is contained in a dispersion medium in which electrophoretic particles are dispersed. provide.
The organic compound is one or a mixture of two or more represented by any one of the following structural formulas (1) to (4), and the content of the organic compound in the dispersion medium is 30% by weight or more. It is preferable that This content is more preferably 80% by weight or more. More preferably, a dispersion medium composed of only one or a mixture of two or more represented by any one of the following structural formulas (1) to (4) is used.
[0009]
[Chemical 2]

[0010]
In the formula, A1 to A6 are benzene ring, cyclohexane ring, dioxane ring, pyrimidine ring, furan ring, tetrahydrofuran ring, dithiane ring, piperidine ring, pyrrazine ring, morpholine ring, cyclopentane ring, cyclobutane ring, pyridine ring, thiophene ring. , A pyrrole ring, or a cyclohexene ring,
X1 to X4, Y1 to Y3, and Z are one or more substituents (hydrogen, fluorine, chlorine, bromine, iodine, cyano group, nitro group, amino group, hydroxyl group, alkanoyloxy group, alkoxycarbonyl group, Carboxy group, trifluoromethyl group, trifluoromethoxy group, alkoxymethylene group, alkyl group, alkoxy group, alkenyl group, alkynyl group, sulfonic acid group, thioalkyl group, mono, di, or trialkylamino group)
B1~B4 either without (single bond rings), COO, OCO, CH = N, N = CH, CH = CH, (CH 2) n O, O (CH 2) n, (CH 2) n , O (CH ₂ ) _n O, CH═CH—COO, OCO—CH═CH, O, CO, NHCO, CONH, N═N, N ₂ O, C≡C, SO, SO ₂ , or NH (N is an integer from 1 to 10),
C1, C2 represents naphthalene, tetrahydronaphthalene, decahydronaphthalene, indene, quinoline, coumarin, azulene, fluorene, dihydrophenanthrene.
[0011]
Specific examples of the structural formulas (1) to (4) include the following (5) to (32).
[0012]
[Chemical 3]

[0013]
[Formula 4]

[0014]
[Chemical formula 5]

[0015]
[Chemical 6]

[0016]
[Chemical 7]

[0017]
In the above structural formula, R1 to R33 and X and Y are as follows.
R1 to R33: alkyl group, alkoxy group, alkoxymethylene group, halogen element, hydrogen, alkenyl group, alkynyl group, cyano group, nitro group, amino group, hydroxyl group, alkanoyloxy group, alkoxycarbonyl group, trifluoromethyl group, Carboxy group, monoalkylamino group, dialkylamino group, trialkylamino group, sulfonic acid group, thioalkyl group, trifluoromethoxy group, acyl group, acyloxy group, formyl group,
X, Y: None (single bond rings), COO, OCO, CH = N, N = CH, CH = CH, (CH 2) n O, O (CH 2) n, (CH 2) n, O (CH ₂ ) _n O, CH═CH—COO, OCO—CH═CH, O, CO, NHCO, CONH, N═N, N ₂ O, C≡C, SO, SO ₂ , NH. In addition, n is an integer of 1-10.
[0018]
Of these organic compounds, it is preferable to use one having a small optical anisotropy. When an organic compound having a large optical anisotropy is used as the dispersion medium, scattering, birefringence, and optical rotation depending on the orientation of the molecules are likely to occur, which causes a reduction in light uniformity. By using a material having small optical anisotropy, particularly one that is optically isotropic, the uniformity of light generated from each pixel of the electrophoretic display device can be improved, and the viewing angle can be reduced. Can be wide.
[0019]
Examples of the organic compound represented by the structural formula of any one of (1) to (4) and having small optical anisotropy include cyclohexylcyclohexane, phenylcyclohexane, phenylethylcyclohexane, phenylcyclohexane Carboxylate type, 4-phenyl-1,3-dioxane type, 2-phenylethyl-1,3-dioxane type and the like can be mentioned.
[0020]
The present invention is preferably applied to an electrophoretic display device having a structure in which an area between electrodes is divided into cells for each pixel and movement of electrophoretic particles is allowed only within each cell.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described.
Although the electrophoretic display device of this embodiment includes an electrophoretic display panel and a peripheral circuit, the feature of the present invention resides in the dispersion liquid that constitutes the electrophoretic display panel, and thus description of the peripheral circuit is omitted. . The electrophoretic display panel of this embodiment will be described with reference to FIGS.
[0022]
The display panel A includes an element substrate 100, a counter substrate 200 disposed to face the element substrate 100, and a cell unit 11 disposed between the two substrates. FIG. 1 is a perspective view showing a state where the counter substrate 200 is removed and lifted upward, and FIG. 2 is a partial cross-sectional view.
A common electrode 201 is formed on a surface of the counter substrate 200 facing the element substrate 100, and a sealing layer 202 is formed thereon. The counter substrate 200, the common electrode 201, and the sealing layer 202 are all transparent, and the counter substrate 200 side is the surface (observation surface) of the display panel A.
[0023]
A pixel electrode 104, a scanning line, a data line 102, and a thin film transistor that functions as a switching element are formed in the central portion (display area 100A) of the element substrate 100 facing the counter substrate 200. In the peripheral region 100B outside the display region 100A, a scanning line driving circuit, a data line driving circuit 140, and external connection electrodes are formed.
[0024]
In addition, a cell portion 11 having a shape in which partition walls 110 are assembled in a lattice shape at a constant height is formed on the display region 100A. For example, the cell portion 11 is formed by sequentially performing a coating film formation process including a photosensitive polyimide precursor on the element substrate 100, an ultraviolet irradiation process through a mask corresponding to the cell pattern, and a development process. It is formed.
[0025]
A portion surrounded by the partition 110 of the cell portion 11 is a cell 11C that divides a region between electrodes (between the common electrode 201 and the pixel electrode 104) for each pixel. All the cells 11C are filled with the dispersion liquid 1 in which the electrophoretic particles 3 are dispersed in the dispersion medium 2. An additive such as a surfactant is added to the dispersion medium 2 as necessary.
Here, since the display panel A is a full-color display body, three adjacent cells 11C are set as one set, and R (red), G (green), and B (blue) are set in the three cells 11C of each set, respectively. ) Is filled. In the dispersion liquid for each color, electrophoretic particles having the same color as the display color are used, and the dispersion medium is dyed so as to be a color that absorbs the display color (for example, a complementary color).
[0026]
Specifically, in the dispersion liquid for R, red particles (for example, iron oxide particles) are used as the electrophoretic particles 3, and the dispersion medium is dyed with a cyan dye. In the dispersion liquid for G, green particles (for example, cobalt green pigment particles) are used as the electrophoretic particles 3, and the dispersion medium is dyed with a magenta dye. In the dispersion for B, blue particles (for example, cobalt blue pigment particles) are used as the electrophoretic particles 3, and the dispersion medium is dyed with a yellow dye.
[0027]
Thereby, when the electrophoretic particles 3 are attracted to the electrode (common electrode 201) on the surface (observation surface) side, the light that has passed through the counter substrate 200 and entered the dispersion 1 is reflected by the electrophoretic particles 3. Therefore, light having a wavelength corresponding to the display color is emitted, and the display color can be seen from the observation surface. When the electrophoretic particles 3 are attracted to the electrode (pixel electrode 104) on the element substrate 100 side, the light transmitted through the counter substrate 200 and incident on the dispersion 1 is reflected by the electrophoretic particles 3, but this reflection Since light (light having a wavelength corresponding to the display color) is absorbed by the dispersion medium, the display color cannot be seen from the observation surface.
[0028]
Here, the position and distribution state of the electrophoretic particles 3 between both electrodes can be controlled by the electric field strength applied to the dispersion liquid 1. Therefore, by controlling the electric field strength applied to the dispersion 1 for each color cell and controlling the position and distribution state of the electrophoretic particles 3 in each color cell, each set of color pixels is changed to a desired color. Since it can be adjusted, this display panel A can display a full-color image.
[0029]
Moreover, in this embodiment, the thing of the composition of Examples 1-19 shown in the following Tables 1-7 is used as the dispersion medium 2.
[0030]
[Table 1]

[0031]
[Table 2]

[0032]
[Table 3]

[0033]
[Table 4]

[0034]
[Table 5]

[0035]
[Table 6]

[0036]
[Table 7]

[0037]
Compared with a dispersion medium composed of only an organic compound having a structural formula containing only one ring, such as dodecylbenzene, the dispersion medium having these compositions is less viscous and less likely to evaporate and soaks into the sealing material. Therefore, the reliability and response speed of the electrophoretic display device are higher than when a dispersion medium composed only of dodecylbenzene is used.
[0038]
【The invention's effect】
As described above, according to the present invention, the reliability and response speed of the electrophoretic display device can be increased.
[Brief description of the drawings]
FIG. 1 is a perspective view showing an electrophoretic display panel constituting an electrophoretic display device corresponding to an embodiment of the present invention, and shows a state where a counter substrate is removed and lifted upward.
FIG. 2 is a partial cross-sectional view of the electrophoretic display panel of FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Dispersion liquid 2 Dispersion medium 3 Electrophoretic particle 11 Cell part 11C Cell 100 Element substrate 100A Display area 100B Peripheral area 102 Data line 104 Pixel electrode 110 Partition 140 Data line drive circuit 200 Counter substrate 201 Common electrode 202 Sealing layer A Display panel

Claims (2)

A dispersion medium in which electrophoretic particles are dispersed, wherein the dispersion medium includes at least one organic compound, and the organic compound is defined by any one of the following formulas (provided that phenylcyclohexane-based material and biphenylcyclohexane) System materials, alkylnaphthalene derivatives, alkylbiphenyl derivatives, diisopropylnaphthalene, decahydronaphthalene, diphenyl ether, benzyl benzoate, octyldiphenyl phosphate, and dicyclohexyl phthalate )

In the formula, A1 to A6 are benzene ring, cyclohexane ring, dioxane ring, pyrimidine ring, furan ring, tetrahydrofuran ring, dithiane ring, piperidine ring, pyrrazine ring, morpholine ring, cyclopentane ring, cyclobutane ring, pyridine ring, thiophene ring. , A pyrrole ring, or a cyclohexene ring,
X1 to X4, Y1 to Y3, and Z are one or more substituents (hydrogen, fluorine, chlorine, bromine, iodine, cyano group, nitro group, amino group, hydroxyl group, alkanoyloxy group, alkoxycarbonyl group, Carboxy group, trifluoromethyl group, trifluoromethoxy group, alkoxymethylene group, alkyl group, alkoxy group, alkenyl group, alkynyl group, sulfonic acid group, thioalkyl group, mono-, di- or trialkylamino group) , Except iodine),
B1~B4 either without (single bond rings), COO, OCO, CH = N, N = CH, CH = CH, (CH 2) n O, O (CH 2) n, (CH 2) n , O (CH ₂ ) _n O, CH═CH—COO, OCO—CH═CH, O, CO, NHCO, CONH, N═N, N ₂ O, C≡C, SO, SO ₂ , or NH (N is an integer from 1 to 10),
C1, C2 represents naphthalene, tetrahydronaphthalene, decahydronaphthalene, indene, quinoline, coumarin, azulene, fluorene, or dihydrophenanthrene.   2. The dispersion medium according to claim 1, wherein the content of the organic compound in the dispersion medium is 30% by volume or more.

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