JP5526607B2 - Display element - Google Patents

Description

  The present invention relates to a display element using an electrowetting phenomenon.

  In recent years, the demand for portable electronic devices has been growing rapidly, and in particular, a light-weight and low-cost display element that can be used as a medium replacing paper is drawing attention. The characteristics required for such a display element include a high white reflectance and a high contrast ratio in addition to a reflection type (non-light-emitting type) that places little burden on the eyes even when referenced for a long time. For example, high-quality display and color display are possible. In recent years, as one means for realizing a reflective display element, a display element capable of displaying information by moving a liquid using an electrowetting phenomenon has been actively developed.

  In order to apply the electrowetting phenomenon to a reflective display element, a closed space for holding fluid in a portion corresponding to a pixel is formed in the element structure, and light for realizing a high reflectivity is formed. It is necessary to use a reflective material.

  In general, in a display element using an electrowetting phenomenon, two types of fluids (water and oil) that do not mix with each other are held in layers on a substrate (steady state (state where no voltage is applied)). . When a voltage is applied between the substrate and the fluid, the oil layer moves or splits so as to reduce the contact area with the substrate. As a result, part of the water enters the oil layer and comes into contact with the substrate, and presents a state (a state where a voltage is applied) different from a steady state (a state where no voltage is applied). As described above, the display element is operated by switching between a plurality of different states, that is, a steady state and a state where a voltage is applied.

  In the display element using the electrowetting phenomenon, in order to make it easier to contact the oil layer than water in the initial state, the substrate surface that is in contact with the fluid is usually water-repellent, for example, by coating with a fluoropolymer. Apply a process that gives However, since the surface subjected to the water repellent treatment has a very low surface tension, there is a problem that the mechanical bonding force is weak. Therefore, the adhesive used when forming the partition for holding the fluid may move into the pixel region, causing display defects. In order to solve this problem, Patent Document 1 discloses that a part of a substrate is hydrophilized in a separation region between pixel regions by laser radiation, UV (Ultra Violet) ozone treatment or oxygen plasma treatment. It has been proposed to solve the above problems.

  As a white display expression method for reflective display, a method using a reflective material in the element structure as disclosed in Patent Documents 1 and 2 and Non-Patent Document 1 is the most common. In Patent Document 2, it is proposed to use a material in which a plurality of kinds of fine particles having different refractive indexes are added to a transparent polymer resin as a reflective material (described as a reflective sheet in the literature). .

  Further, Patent Document 2 discloses a method of opening using excimer laser processing or a micro drill as a method of forming a space for holding a fluid in a polymer resin in which fine particles are dispersed.

  However, the above display device has the following problems.

  In the case of the display element disclosed in Patent Document 1, it is difficult to accurately hydrophilize only the bonding portion of the partition wall by physical surface treatment, particularly when manufacturing a high-definition display element. there were. No countermeasure is disclosed in Patent Document 1 for the problem that it is difficult to hydrophilize only the bonded portion of the partition wall with high accuracy.

  In addition, in the case of the display element disclosed in Patent Document 1, Patent Document 1 does not specifically disclose the material of the reflector (described as a reflector in the document), the lamination method, and the like. There was a problem that it could not be manufactured by a simple process.

  Similarly, in Non-Patent Document 1, there is only a description about using a reflective electrode, and there is no specific disclosure for accurately hydrophilizing only the bonding portion of the partition wall. Further, there is no specific disclosure of the material of the reflecting material, the lamination method, and the like, and there is a problem that it cannot be manufactured by a simple process.

  Further, as disclosed in Patent Document 2, dust may be generated when an excimer laser process or a micro drill is used as a method for forming a space for holding a fluid in a polymer resin in which fine particles are dispersed. In addition, there is a problem that it cannot be efficiently manufactured.

  An object of the present invention is to provide a display element that has a high white reflectance and a contrast ratio and can be manufactured by a simple process in view of the problems of the prior art.

  In order to solve the above-described problems, the present invention is characterized by the following measures.

  The first invention includes a holding space that is formed between two opposing substrates and holds two types of fluids that are not mixed with each other, and a voltage is applied between the two substrates across the holding space. A display element having fluid moving means for moving two kinds of fluids into two different states, comprising a partition part for dividing the holding space, wherein the fluid moving means is provided on a transparent first substrate. A first transparent electrode formed on the second substrate side, and a second transparent electrode formed on the first substrate side of the second substrate via a support layer, the support layer comprising: It is formed using a light-reflective photosensitive resist material, and the partition wall is formed integrally with the support layer.

  According to a second invention, in the display element according to the first invention, the photosensitive resist material is a material containing a white inorganic pigment.

  According to a third aspect of the present invention, in the display element according to the first or second aspect of the invention, the fluid moving means includes a surface layer that covers a surface of the second transparent electrode, and the surface layer is the first element. The surface tension of the surface layer is changed by applying a voltage between the transparent electrode and the second transparent electrode.

  According to a fourth aspect of the present invention, in the display element according to any one of the first to third aspects, the first type fluid of the two types of fluid is light transmissive, and the second type fluid is predetermined. It is characterized by being colored in the color of.

  According to a fifth aspect of the present invention, in the display element according to the fourth aspect of the invention, the first type fluid has conductivity or polarity.

  According to a sixth aspect of the present invention, in the display element according to the fourth or fifth aspect, the wall surface of the partition wall is covered with a second surface layer formed integrally with the surface layer, and the second surface layer The interfacial tension of the surface layer is larger than the interfacial tension of the surface layer.

  A seventh invention includes a holding space that is formed between two opposing substrates and holds two types of fluids that are not mixed with each other, and a voltage is applied between the two substrates so that the two types of fluids are A display element having fluid moving means for moving to two different states, wherein the fluid moving means includes a first transparent electrode formed on the second substrate side of the transparent first substrate, and the second A second transparent electrode formed on the first substrate side of the substrate via a support layer, the support layer is formed using a light-reflective photosensitive resist material, and the holding space is It includes a first space sandwiched between the first transparent electrode and the second transparent electrode, and a second space provided in the support layer.

  An eighth invention is the display element according to the seventh invention, wherein the photosensitive resist material is a material containing a white inorganic pigment.

  According to a ninth invention, in the display element according to the seventh or eighth invention, the fluid moving means includes a surface layer that covers a surface of the second transparent electrode, and the surface layer is the first element. The surface tension of the surface layer is changed by applying a voltage between the transparent electrode and the second transparent electrode.

  According to a tenth invention, in the display element according to any one of the seventh to ninth inventions, the first type fluid of the two types of fluid has light permeability, and the second type fluid is predetermined. It is characterized by being colored in the color of.

  An eleventh invention is characterized in that in the display element according to the tenth invention, the second type fluid has conductivity or polarity.

  According to a twelfth invention, in the display element according to any one of the first to eleventh inventions, a color filter is provided on the second substrate side of the first substrate.

  A thirteenth aspect of the invention is the display element according to any one of the fourth to sixth, tenth or eleventh aspects, wherein the first color is colored in each of a plurality of primary colors corresponding to a plurality of primary colors capable of full color display. The holding spaces holding the type of fluid or the second type of fluid are regularly arranged.

  According to the present invention, a display element having a high white reflectance and a contrast ratio can be manufactured by a simple process.

It is sectional drawing which shows typically the structure of the display element which concerns on the 1st Embodiment of this invention. It is sectional drawing which shows typically the structure of the display element which concerns on the 2nd Embodiment of this invention. It is an upper surface schematic diagram of the 2nd board | substrate in the display element which concerns on the 2nd Embodiment of this invention. It is sectional drawing which shows typically the structure of the display element which concerns on the modification of the 2nd Embodiment of this invention. It is sectional drawing which shows typically the structure of the display element which concerns on the 3rd Embodiment of this invention. It is sectional drawing which shows typically the structure of the display element which concerns on the 4th Embodiment of this invention.

Next, a mode for carrying out the present invention will be described with reference to the drawings.
(First embodiment)
First, the display element according to the first embodiment of the present invention will be described.

  FIG. 1 is a cross-sectional view schematically showing the configuration of the display element according to the present embodiment. FIG. 1A shows a steady state (a state where no voltage is applied), and FIG. 1B shows a state where a voltage is applied.

  As shown in FIG. 1A, the display element 10 according to the present embodiment is formed between the first and second substrates 11 and 12 by the first and second fluids FL1 and FL2 that are not mixed with each other. The pixel 15 formed in the holding space 13 is provided. The display element 10 according to the present embodiment includes a transparent first substrate 11 and a second substrate 12. The first and second substrates 11 and 12 face each other. In addition, the display element 10 includes a holding space 13 and a fluid moving unit 20 in the pixel 15. The display element 10 applies a voltage to the pixel 15 between the first and second substrates 11 and 12 across the holding space 13 to move the two types of fluids FL1 and FL2 to two different states. It has a moving means 20. In addition, the display element 10 includes a partition wall portion 17 for dividing the holding space 13. Each holding space 13 divided by the partition wall portion 17 constitutes each pixel 15.

  The first fluid FL1 and the second fluid FL2 in the present embodiment correspond to the second type fluid and the first type fluid in the present invention, respectively. In addition, the holding space 13 in the present embodiment corresponds to a “divided holding space” obtained by dividing the holding space in the present invention by the partition walls. That is, the holding space in the present invention means an entire space in which a plurality of holding spaces 13 divided by the partition wall portion 17 in the present embodiment are combined.

  Further, in FIGS. 1A and 1B, only one pixel 15 is shown as a representative. Further, by repeatedly forming the pixels 15 surrounded by the dotted lines in FIGS. 1A and 1B in the horizontal direction, the display element 10 having a plurality of pixels 15 can be configured.

  A first transparent electrode 21 is formed on the second substrate 12 side of the first substrate 11. A second transparent electrode 22 is formed on the first substrate 11 side of the second substrate 12. The first transparent electrode 21 and the second transparent electrode 22 constitute the fluid moving means 20. That is, the fluid moving means 20 includes a first transparent electrode 21 and a second transparent electrode 22.

  The second transparent electrode 22 is formed on the first substrate 11 side of the second substrate 12 via a light reflective support layer 16. The second transparent electrode 22 is covered with a surface layer 23 on the surface. The first and second transparent electrodes 21, 22 that are fluid moving means 20 apply a voltage between the first and second transparent electrodes 21, 22 to cover the surface of the second transparent electrode 22. By controlling the interfacial tension of the layer 23, the first and second fluids FL1, FL2 are moved to two different states. That is, the fluid moving means 20 includes the surface layer 23.

  In the display element 10 according to the present embodiment, the partition wall portion 17 is formed integrally with the support layer 16, so that the partition wall portion 17 and the support layer 16 have a U-shape as shown in FIG. And forming a recess. The second transparent electrode 22 is formed on the surface of the support layer 16 excluding the partition wall portion 17.

  The wall surface of the partition wall portion 17 is covered with a second surface layer 24 formed integrally with the surface layer 23. Therefore, as shown in FIG. 1, the holding space 13 has the first transparent electrode 21 formed on the transparent first substrate 11 as a ceiling surface, and the support layer 16 and the second transparent electrode on the second substrate 12. This is a space formed with the surface layer 23 formed through the electrode 22 as a bottom surface and the second surface layer 24 covering the partition wall portion 17 as a side surface.

  In other words, in the display element 10 according to the present embodiment, the pixel 15 includes a fluid holding space 13 between the first substrate 11 and the second substrate 12, and includes the fluid holding space 13. The first and second fluids FL1 and FL2 that do not mix with each other are contained. The transparent first substrate 11 on the viewing surface side of the display element 10 includes a first transparent electrode 21, and the second substrate 12 is a surface layer in order from the side in contact with the first and second fluids FL 1 and FL 2. 23, the second transparent electrode 22, and the light reflective support layer 16. Moreover, the partition part 17 which is a wall part of the holding space 13 and the support layer 16 contain the same material.

  The light-reflective support layer 16 is patterned by a photolithographic technique using a photosensitive resist material whose physical properties are changed by irradiation with light rays or electron beams. As the photosensitive resist material, conventionally known materials used in plate making and printed circuit board manufacturing processes can be used, and in particular, a solder resist used for insulating a printed circuit board, particularly a white solder resist used for LED mounting. It is possible to apply suitably. A photosensitive resist material is applied to the second substrate 12 and then exposed through a photomask to partially change the solubility of the developer. Thereafter, development processing is performed to partially remove the resist material, whereby the fluid holding space 13 is formed. The photosensitive resist material used in the present invention is light reflective and desirably contains a white inorganic pigment. Thereby, since external light is scattered by the refractive index difference with the particle | grain surface of a white inorganic material and a resist base material, a white display with high visibility is attained. In addition, since there is an effect of preventing light leakage between adjacent pixels 15, an improvement in contrast ratio can be expected. As the white inorganic pigment, titanium oxide, zinc oxide, barium sulfate, lithopone, and the like can be used. Among these, titanium oxide having excellent visible light scattering performance is preferable.

  As the surface layer 23 and the second surface layer 24, those having water repellency are suitable, and a fluororesin is suitably used. Specifically, Cytop resin (trade name: manufactured by Asahi Glass), Teflon (registered trademark) (trade name: manufactured by DuPont), or a perfluorinated polymer deposited by sputtering or a gas phase reaction method is suitable. Further, the surface layer 23 and the second surface layer 24 may have a multilayer structure in which the above-described fluorine-based resin is stacked on a transparent insulating material such as parylene.

  The first and second transparent electrodes 21 and 22 are formed of various materials including indium oxide (ITO).

  In the display element 10 according to the present embodiment, the first fluid FL1 is obtained by coloring a fluid that is not mixed with the second fluid FL2, and a dye is contained in silicon oil, hydrocarbon oil, fluorocarbon oil, or the like. Can be used. The second fluid FL2 is a fluid that exhibits conductivity or polarity and has optical transparency, and for example, water or alcohols can be used. The color of the first fluid FL1 is one of three complementary colors capable of creating a color spectrum, such as cyan, magenta, and yellow, for example, and the pixel 15 having the holding space 13 holding each of the three complementary colors is defined. By arranging them in full, a full color display becomes possible.

  In the display element 10 according to the present embodiment, the support layer 16 exists on the entire bottom of the holding space 13. Even if the support layer 16 is not present at a part of the bottom, the object of the present invention can be achieved. However, it is desirable that the support layer 16 be present on the entire bottom for the purpose of ensuring reflectivity. Since the light-reflecting support layer 16 is present on the entire bottom, a high reflectivity of the pixel 15 can be achieved and the contrast can be improved. Further, when the photosensitive resist contains a white inorganic pigment, the light does not easily reach the inside of the resist material during exposure. However, when the photosensitive resist is a positive resist, the photosensitive resist material can be left at the bottom as shown in FIG. 1A by adjusting the exposure conditions. By leaving the photosensitive resist material at the bottom, a recess composed of the partition wall 17 and the support layer 16 can be formed.

  In the steady state (state where no voltage is applied), as shown in FIG. 1A, the first fluid FL1 and the second fluid FL2 exist in two layers, and the first fluid FL1 is on the surface. Since it is in contact with the layer 23, the pixel 15 exhibits the color of the first fluid FL1.

  On the other hand, when a voltage is applied, when a voltage is applied between the first transparent electrode 21 and the second transparent electrode 22, as shown in FIG. When the tension, that is, the wettability is changed, the first fluid FL1 moves so as to reduce the contact area with the surface layer 23, and instead of the first fluid FL1, a part of the second fluid FL2 is replaced with the surface layer. It moves so that it may contact 23. As a result, the portion of the holding space 13 of the pixel 15 where the second fluid FL2 is adjacent to the surface layer 23 is in a light-transmitting state. By using the fluid moving means 20 which is such an electrical means, the light absorption state and the transmission state can be switched at high speed and reversibly.

The interfacial tension of the surface of the holding space 13 is preferably such that the surface tension of the partition wall portion 17 that is the wall portion of the holding space 13 is larger than the surface tension of the bottom portion of the holding space 13. That is, the interfacial tension of the second surface layer 24 is desirably larger than the interfacial tension of the surface layer 23. When the interfacial tension of the second surface layer 24 is greater than the interfacial tension of the surface layer 23, the second surface layer 24 of the partition wall portion 17 that is the wall portion is more fluid than the first surface layer 23 that is the bottom portion. It is difficult to get wet with colored oil. Therefore, even if the holding space 13 is not completely closed between adjacent pixels 15, the colored oil that is the first fluid FL <b> 1 mixes along the partition wall 17 that is the wall portion of the holding space 13. This can be suppressed. The interfacial tension of the second surface layer 24 can be made larger than the interfacial tension of the surface layer 23 by appropriately adjusting the film formation conditions when forming the surface layer 23 and the second surface layer 24.
(Second Embodiment)
Next, a display element according to a second embodiment of the present invention will be described with reference to FIGS.

  The display element according to the present embodiment is different from the display element according to the first embodiment in that a part of a space for holding two types of fluid is provided in the support layer.

  FIG. 2 is a cross-sectional view schematically showing the structure of the display element according to the present embodiment. FIG. 2A shows a steady state (a state where no voltage is applied), and FIG. 2B shows a state where a voltage is applied. FIG. 3 is a schematic top view of the second substrate in the display element according to the present embodiment. However, in the following text, the same reference numerals are given to the portions described above, and the description may be omitted (the same applies to the following embodiments and modifications).

  As shown in FIG. 2A, in the first embodiment, the holding space for holding two types of fluid is a space formed between the first transparent electrode and the second transparent electrode. Unlike the above, the display element 10a according to the present embodiment includes a space sandwiched between the first transparent electrode 21 and the second transparent electrode 22a and a space provided in the support layer 16a.

  In the present embodiment, a space sandwiched between the first transparent electrode 21 and the second transparent electrode 22a is defined as a display space 14, and a space provided in the support layer 16a is defined as a holding space 13a. To do. The display space 14 and the holding space 13a correspond to the first space and the second space in the present invention, respectively.

  As shown in FIG. 2A, in the display element 10a according to the present embodiment, the first and second fluids FL3 and FL4 which are not mixed with each other are formed between the first and second substrates 11 and 12. And a display space 14 and a pixel 15a held in a holding space 13a provided in the support layer 16a. The display element 10a according to the present embodiment includes the transparent first substrate 11 and the second substrate 12 facing the first substrate 11, as in the first embodiment. Further, the display element 10a applies a voltage between the first and second substrates 11 and 12 across the display space 14 to the pixel 15a so that the two types of fluids FL3 and FL4 are in two different states. It has fluid moving means 20a to move. Further, the display element 10a includes a partition wall portion 17a for dividing a space including the display space 14 and the holding space 13a for each pixel 15a.

  The first fluid FL3 and the second fluid FL4 in the present embodiment correspond to the first type fluid and the second type fluid in the present invention, respectively.

  2A and 2B show only one pixel 15a as a representative, as in FIGS. 1A and 1B. Further, by repeatedly forming the pixels 15a surrounded by the dotted lines in FIGS. 2A and 2B in the horizontal direction, a display element 10a having a plurality of pixels 15a can be configured.

  In FIGS. 2 (a) and 2 (b), the boundary between the first fluid FL3 and the second fluid FL4 is shown by a straight line for easy explanation. Depending on the magnitude relationship of the interfacial tension between the fluid FL3, the second fluid FL4, the holding space 13a, and the display space 14, there may be a complicated shape indicated by a partial curve.

  A first transparent electrode 21 is formed on the second substrate 12 side of the first substrate 11. The surface of the first transparent electrode 21 is covered with a surface layer 23c.

  Further, a second transparent electrode 22a is formed on the first substrate 11 side of the second substrate 12 via a light reflective support layer 16a. Further, the surface of the second transparent electrode 22a is covered with the surface layer 23a.

  The fluid moving means 20a includes a first transparent electrode 21, a second transparent electrode 22a, and a surface layer 23a.

  However, as shown in FIG. 2A, a part of the support layer 16a is removed, and a holding space 13a is provided. In the example shown in FIG. 2A, a through hole is provided in the support layer 16a, and a holding space 13a is provided. In the region where the holding space 13a is provided, since the support layer 16a does not exist, the second transparent electrode 22a does not exist and the surface layer 23a does not exist. Accordingly, the holding space 13a is connected to the display space 14 which is a space sandwiched between the first transparent electrode 21 and the second transparent electrode 22a. It is sufficient that a space for holding a fluid is formed in the support layer 16a, and it is not necessary to remove the support layer 16a so as to penetrate until the second substrate 12 is exposed.

  In other words, the pixel 15a divided by the partition wall 17a has a holding space 13a for holding a fluid and a display space 14 extending above the holding space 13a, and the display space 14 is mixed in the holding space 13a. The first fluid FL3 and the second fluid FL4 are not contained. The transparent first substrate 11 corresponding to the viewing surface side of the display element 10a includes a first transparent electrode 21, and the second substrate 12 is a region other than the holding space 13a from the side in contact with the fluids F3 and FL4. In order, it has the surface layer 23a, the 2nd transparent electrode 22a, and the light-reflective support layer 16a. Further, since the wall portion of the holding space 13a is the support layer 16a, the wall portion of the holding space 13a and the support layer 16a contain the same material.

  As shown in FIG. 3, in the display element 10a, the pixels 15a divided by the partition walls 17a are arranged vertically and horizontally in a plane.

  The second transparent electrode 22a on the second substrate 12 is electrically divided between the adjacent holding spaces 13a. As a specific forming method, a method of forming the second transparent electrode 22a in a state where a masking material is arranged at the boundary portion of the pixel 15a, or photolithography and etching after forming the second transparent electrode 22a. A method including removing a boundary portion by performing a process including the above can be used.

  Each layer constituting the display element 10a according to the present embodiment can be formed using the same materials and methods as those described for the display element 10 according to the first embodiment. The surface layer 23c covering the surface of the first transparent electrode 21 can also be formed by the same material and method as the surface layer 23a covering the surface of the second transparent electrode 22a. Further, the partition walls 17a between the pixels 15a are formed by patterning using photolithography or a conventionally known printing technique using a material that meets the purpose of preventing fluid mixing in the adjacent display space. .

  In the present embodiment, the first fluid FL3 is a fluid that does not mix with the second fluid FL4 and has light permeability, and silicon oil, hydrocarbon oil, fluorocarbon oil, or the like can be used. In addition, the second fluid FL4 is a fluid having conductivity or polarity that is not mixed with the first fluid FL3 and is colored in a predetermined color, and water or alcohol containing a dye or a pigment is dispersed. Things can be used.

  In the steady state (state where no voltage is applied), as shown in FIG. 2A, the surface of the display space 14 is water repellent, and therefore the first fluid FL3 is distributed in the display space 14. The second fluid FL4 is distributed in the space 13a. Since the first fluid FL3 exists in the display space 14, outside light is reflected by the light-reflecting support layer 16a except for the upper portion of the holding space 13a of the pixel 15a, and macroscopically white. Presents.

  On the other hand, when a voltage is applied, as shown in FIG. 2B, when a voltage is applied between the first transparent electrode 21 and the second transparent electrode 22a, the interface of the surface layer 23a. By changing the tension, that is, the wettability, the second fluid FL4 moves so as to spread from the holding space 13a to the display space 14, and the first fluid FL3 moves from the display space 14 to the holding space 13a. . Thereby, the pixel 15a exhibits the color of the second fluid FL4. By using the fluid moving means 20a which is such an electrical means, the light absorption state and the transmission state can be switched at high speed and reversibly.

  Since the display switching of the display element 10a according to the present embodiment is realized by switching the two types of fluids FL3 and FL4 between the holding space 13a and the display space 14, the volume of the holding space 13a and the display space 14 is changed. That is, it is desirable that the volumes of the first fluid FL3 and the second fluid FL4 are equal. Further, in order to improve the reflectance in a steady state (state where no voltage is applied), it is better that the ratio of the holding space 13a to the pixel 15a is as small as possible. For this purpose, the aspect ratio of the holding space 13a is increased. It is necessary to. Further, if the thickness of the display space 14 is reduced, the holding space 13a can be inevitably reduced. However, when the thickness of the display space 14 is reduced, the underlying support layer 16a is applied in a state where a voltage is applied. , And contrast decreases. Therefore, it is necessary to adjust the thickness within a range in which the support layer 16a can be sufficiently concealed. In this configuration, it is more desirable that the support layer 16a does not exist at least at a part of the bottom of the holding space 13a. Thereby, the contrast ratio of the pixel 15a can be improved by deepening the holding space 13a and improving the aspect ratio.

In the present embodiment, since the surface of the first transparent electrode 21 is covered with the surface layer 23c, a steady state (state in which no voltage is applied) and a voltage are also applied to the ceiling surface of the display space 14. The interfacial tension can be greatly changed between the applied states. Therefore, it is possible to further improve the contrast ratio of the pixel 15a between a steady state (a state where no voltage is applied) and a state where a voltage is applied.
(Modification of the second embodiment)
Next, a display element according to a modification of the second embodiment of the present invention will be described with reference to FIG.

  The display element according to this modification is the second embodiment in that the second transparent electrode is formed so as to be connected from the surface of the display space to the bottom thereof through at least a part of the wall portion of the holding space. This is different from the display element according to the embodiment.

  FIG. 4 is a cross-sectional view schematically showing the structure of the display element according to this modification. FIG. 4A shows a steady state (state where no voltage is applied), and FIG. 4B shows a state where voltage is applied.

  As shown in FIG. 4A, the display element 10b according to this modification is the same as that of the second embodiment except for the holding space 13b. On the other hand, in the display element 10b according to this modification, the second transparent electrode 22b is formed so as to be connected to the bottom thereof through the wall portion of the holding space 13b.

  In the display element 10b according to the present modification, the second transparent electrode 22b is provided on the wall and bottom of the holding space 13b, but the surface layer whose interface tension is controlled by the second transparent electrode 22b is not formed. . Therefore, by applying a voltage between the first transparent electrode 21 and the second transparent electrode 22b, the interfacial tension between the fluid in the holding space 13b itself hardly changes. Therefore, in the display switching operation of the display element 10b according to the present modification, the same effects as those of the display element 10a according to the second embodiment can be obtained.

  In a steady state (state where no voltage is applied), as shown in FIG. 4A, the surface of the display space 14 is water-repellent, so the first fluid FL3 is distributed in the display space 14. The second fluid FL4 is distributed in the holding space 13b. Since the first fluid FL3 exists in the display space 14, outside light is reflected by the light-reflecting support layer 16a except for the upper portion of the holding space 13b of the pixel 15b. Presents.

  On the other hand, when a voltage is applied, as shown in FIG. 4B, when a voltage is applied between the first transparent electrode 21 and the second transparent electrode 22b, the interface of the surface layer 23a. By changing the tension, that is, the wettability, the second fluid FL4 moves so as to spread from the holding space 13b to the display space 14, and the first fluid FL3 moves from the display space 14 to the holding space 13b. Thereby, the pixel 15b exhibits the color of the second fluid FL4. By using the fluid moving means 20b which is such an electrical means, the light absorption state and the transmission state can be switched at high speed and reversibly. Therefore, the effect of the present invention can be obtained regardless of whether the second transparent electrode is present on the wall portion of the holding space 13b.

Further, for example, in order to connect each pixel 15b to a means for independently driving, such as a source electrode of a lower layer thin film transistor (TFT) in a display element according to a fourth embodiment described later. The second transparent electrode 22b is preferably connected from the surface of the display space 14 to the bottom of the holding space 13b through at least a part of the wall portion of the holding space 13b.
(Third embodiment)
Next, a display element according to a third embodiment of the present invention will be described with reference to FIG.

  The display element according to the present embodiment is different from the display element according to the first embodiment in that color display is enabled by providing a color filter on the transparent first substrate 11.

  FIG. 5 is a cross-sectional view schematically showing the configuration of the display element according to the present embodiment.

  As shown in FIG. 5, the display element 30 according to the present embodiment has a color filter in each of the pixels 15 c to 15 e, unlike the first embodiment in which no color filter is provided in each pixel. Is provided.

  As shown in FIG. 5, the display element 30 according to the present embodiment holds two types of fluids FL1 and FL2 that are not mixed with each other in a holding space 13 formed between the first and second substrates 11 and 12. The display element 30 according to the present embodiment includes a transparent first substrate 11 and a second substrate 12 facing the first substrate 11, and each pixel. The fact that the holding space 13 and the fluid moving means 20 are provided in 15c to 15e, and the partition wall portion 17 that forms the holding space 13 for each of the pixels 15c to 15e is provided, as in the first embodiment. It is the same.

  In addition, the first transparent electrode 21 is formed on the second substrate 12 side of the first substrate 11, and the second transparent electrode 22 is formed on the first substrate 11 side of the second substrate 12. The formation of the first transparent electrode 21 and the second transparent electrode 22 constitutes the fluid moving means 20 as in the first embodiment.

  The second transparent electrode 22 is formed on the first substrate 11 side of the second substrate 12 via the light-reflective support layer 16, and the surface is covered with the surface layer 23. Is the same as that of the first embodiment.

  On the other hand, in the display element 30 according to the present embodiment, a color filter 31 that exhibits a different color for each pixel 15 is formed on the first transparent electrode 21 of the first substrate 11.

  As the color filter 31, the color filter 31 can be formed by forming a colored layer containing a pigment exhibiting each color such as red, green, and blue in a conductive material or an insulating material. When the display element 30 including the color filter 31 is used, it is desirable that the coloring fluid of the display element 30 is colored using a black dye or pigment. The black color here is sufficient if it absorbs most of the visible light such as dark gray, dark blue, dark brown, dark green, etc. and is recognized by the human eye in a black color tone.

  By arranging the colors of the adjacent color filters regularly, the display element 30 capable of color display can be configured. In the example shown in FIG. 5, the colors of the color filters 31a, 31b, and 31c of the pixels 15c, 15d, and 15e can be set to red, green, and blue in order from the left. As described above, the coloring pattern may include three primary colors necessary for full-color display, such as red, green, blue, cyan, magenta, and yellow, or an uncolored portion in addition to the three primary colors.

  The pattern shape of the color filter is not particularly limited, but it is easy to manufacture a pattern in which square or rectangular patterns are regularly arranged.

  On the other hand, a fluid colored in a predetermined color held in the holding space 13 is provided according to a plurality of primary colors capable of full-color display, and the pixels 15 having the holding spaces 13 are regularly arranged, thereby providing a color. The display element 30 is capable of display. A desired color can be displayed by appropriately applying a voltage to each pixel 15. For example, when each of the colors corresponding to a plurality of primary colors capable of full color display is red, green, and blue, a first fluid colored in each of red, green, and blue is prepared, and the first fluid is prepared. By configuring the pixels having a holding space that holds the color to be regularly arranged in the order of red, green, and blue, full-color display is possible.

The display element 30 according to the present embodiment has the same configuration as each pixel 15a of the display element 10a according to the second embodiment, instead of each pixel 15 of the display element 10 according to the first embodiment. Or the same configuration as each pixel 15b of the display element 10b according to the modification of the second embodiment can be used.
(Fourth embodiment)
Next, a display element according to a fourth embodiment of the present invention will be described with reference to FIG.

  The display element according to the present embodiment is different from the display element according to the second embodiment in that a switching element made of a TFT is provided corresponding to each pixel of the display element. It is different from the display element concerning.

  FIG. 6 is a cross-sectional view schematically showing the configuration of the display element according to the present embodiment.

  As shown in FIG. 6, in the second embodiment, the display element is composed of a transparent first substrate and a second substrate, and this embodiment is different from the case where each pixel is not provided with a TFT. The display element 40 includes a third substrate 41 in addition to the first and second substrates 11 and 12, and the third substrate 41 is provided with a switching element made of TFT corresponding to each pixel 15b. It has been.

  As shown in FIG. 6, the configuration of each pixel 15b provided between the transparent first substrate 11 and the second substrate 12 is the same as each pixel of the display element 10b according to the modification of the second embodiment. The configuration is the same as that of 15b.

  On the other hand, the display element 40 according to the present embodiment has a third substrate 41 on the opposite side of the first substrate 11 with the second substrate 12 as the center, and the second substrate 12 A gate electrode 42 is formed on the substrate 12 side, a gate insulating film 43 is formed so as to cover the gate electrode 42, an organic semiconductor layer 44 is formed on the surface of the gate insulating film 43, and the organic semiconductor layer 44 and the gate insulation are formed. A source electrode 45 and a drain electrode 46, which are a pair of electrodes separated from each other, are formed so as to cover the film 43, and are bonded to the second substrate 12 through an adhesive layer 47. As the adhesive layer 47, for example, an anisotropic conductive adhesive film ACF (Anisotropic Conductive Film) can be used. In addition, a via hole 48 is formed in the second substrate 12 to electrically connect, for example, the second transparent electrode 22b formed in the holding space 13b and the source electrode 45 of the third substrate 41. A through electrode 49 using copper or the like is formed in the via hole 48.

  According to the display element 40 according to the present embodiment, since a switching element is formed for each pixel 15b, display switching can be easily controlled for each pixel.

Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not construed as being limited to the examples.
Example 1
A first substrate 11 and a second substrate 12 made of transparent glass were prepared.

  ITO was formed on the first substrate 11 as the first transparent electrode 21. On the second substrate 12, a positive photosensitive resist material in which a white pigment is dispersed is applied and formed, and exposed and developed through a positive mask in which a portion to be a fluid holding space 13 is opened, whereby a partition wall A support layer 16 having a portion 17 and a recess capable of holding a fluid was formed. In the development process, the exposure condition was set in a range where the resist in the exposed portion was not completely dissolved, so that the resist material was also left at the bottom of the holding space 13. The thickness of the support layer 16 (the height of the wall of the support layer from the substrate surface) was 20 μm. Subsequently, ITO is patterned on the bottom of the holding space 13 as the second transparent electrode 22, and a commercially available fluorinated polymer is dissolved in a solvent, and the coating conditions are adjusted so that the thickness becomes 200 nm, and then spin is performed. The surface layer 23 was formed by coating and baking.

  As fluids used for display, water FL2 and alkane oil FL1 colored with a black non-polar dye were prepared. Oil FL1 is injected into the pixel holding space 13 using an ink jet, and subsequently water FL2 is injected in the same manner so that the surface of the first substrate 11 on the first transparent electrode 21 side made of ITO is on the inside. The two fluids FL1 and FL2 were sealed, and the display element 10 shown in FIG. 1 was obtained.

The display element 10 obtained by the above procedure exhibits black color due to the oil FL1 in a steady state (a state where no voltage is applied), and the water FL2 in the holding space 13 emits light in a state where a voltage is applied. Since it is transmitted and reflected by the support layer 16, white is presented. Good display performance was confirmed by appropriately applying a voltage to a desired portion between the substrates 11 and 12.
(Example 2)
A polycarbonate substrate having a thickness of 120 μm was prepared as the first and second substrates 11 and 12. As two types of fluids that were not mixed with each other, a conductive liquid FL4 in which a predetermined amount of black pigment was dispersed and an alkane-based oil FL3 were prepared.

  The first transparent electrode 21 made of ITO is patterned on the first substrate 11 so as to be formed on the pixel portion, and then parylene is formed as a dielectric layer with a thickness of 300 nm by chemical vapor deposition. After forming a film with a thickness, a fluorinated polymer dissolved in a solvent was spin-coated and baked to form a water-repellent surface layer 23c having a thickness of 100 nm. A negative photosensitive solder resist material in which titanium oxide fine particles are dispersed is applied and formed on the second substrate 12, and exposure and development are performed through a negative mask in which a portion serving as a fluid holding space 13 a serves as a light shielding portion. Thus, the support layer 16a having the holding space 13a for holding the fluid was formed. The resist thickness was 40 μm, and the holes for holding the fluid were formed with a diameter D of 400 μm and a pitch P of 1000 μm shown in FIG. Next, ITO was formed as the second transparent electrode 22a by patterning so as to cover the region corresponding to the display space 14 and to be separated from the adjacent pixels through a space of 100 μm. Further, a surface layer 23a was formed by dissolving a commercially available fluorinated polymer in a solvent, adjusting the coating conditions so as to have a thickness of 200 nm, and spin-coating and baking. A partition wall portion 17a was formed using a white UV curable resin at a boundary portion of each pixel on the surface layer 23a.

  Using a microcapillary dropping method, a black conductive liquid FL4 was introduced into the holding space 13a, and oil FL3 was filled thereon. This was aligned with the first transparent electrode 21 made of ITO and the surface layer 23c formed on the first substrate 11 and bonded to obtain the display element 10a shown in FIG.

In the display element 10a obtained by the above procedure, in a steady state (a state where no voltage is applied), the color of the resist material of the support layer 16a is transmitted in the display space 14 excluding the upper part of the holding space 13a. The color was white and the reflectance of visible light was 67%. Further, in a state where a voltage was applied, the black conductive liquid FL4 moved so as to spread from the holding space 13a to the display space 14, and the visible light reflectance was 4%. Good display performance was confirmed by appropriately applying a voltage to desired portions of both substrates 11 and 12.
(Example 3)
A first substrate 11 and a second substrate 12 made of transparent glass were prepared. As fluids used for display, water FL2 and alkane oil FL1 colored with a nonpolar dye exhibiting black were prepared.

  On the 1st board | substrate 11, ITO was formed as sputtering as the 1st transparent electrode 21, and it patterned for every pixel area. Subsequently, an ITO solution in which an ITO solution in which inorganic pigments exhibiting red, green, and blue colors are dispersed is prepared, and is sequentially ejected and baked on the ITO so as to be regularly arranged using an ink jet method. As a result, the color filter 31 was formed. The discharge position and the discharge amount were adjusted in advance so that the adjacent color filters 31 did not overlap.

  On the second substrate 12, a positive photosensitive resist material in which a white pigment is dispersed is applied and formed, and exposed and developed through a positive mask in which a portion serving as a fluid holding space 13 is opened, whereby a partition wall portion 17 and a support layer 16 having a recess capable of holding fluid was formed. In the development process, the exposure condition was set in a range where the resist in the exposed portion was not completely dissolved, so that the resist material was also left at the bottom of the holding space 13. Subsequently, the second transparent electrode 22 made of ITO was formed by patterning on the bottom of the holding space 13, and the surface layer 23 was formed thereon by dissolving the fluorinated polymer in a solvent, spin coating, and baking.

  After black oil FL1 is sequentially injected into the holding space 13 of the pixel 15 using an ink jet and subsequently water FL2 is similarly injected, the first transparent electrode 21 made of ITO on the first substrate 11 and the color filter 31 are injected. The display element 30 shown in FIG. 5 was obtained by aligning and fixing the boundary so that the boundary between and the partition wall portion 17 were aligned.

The display element 30 obtained by the above procedure exhibits a black color in a steady state (state where no voltage is applied), and when a voltage is applied, reflected light from the white resist material of the support layer 16 passes through the color filter 31. Since it can be seen, each color of the color filter 31 is presented. Stable color display performance could be confirmed by appropriately applying a voltage to a desired position between the substrates 11 and 12.
Example 4
A first substrate 11, a second substrate 12, and a third substrate 41 made of transparent glass were prepared. As the second substrate 12, a substrate in which a via hole 48 filled with a conductive material in advance according to the pixel pitch was formed was used. As the liquids that are not mixed with each other used for display, three kinds of conductive liquids FL4 in which a predetermined amount of cyan, magenta, and yellow pigments are dispersed and a transparent alkane-based oil FL3 were prepared.

  The first transparent electrode 21 made of ITO is patterned on the first substrate 11 so as to be formed on the portion to be the pixel 15b, and then parylene is formed as a dielectric layer by a chemical vapor deposition method to 300 μm. Then, a fluorinated polymer dissolved in a solvent was spin-coated and baked to form a water-repellent surface layer 23c having a thickness of 100 nm.

  On the second substrate 12, a negative photosensitive solder resist material in which titanium oxide fine particles were dispersed was applied and formed. Next, the fluid holding space 13a is exposed and developed through a negative mask in which the portion serving as the fluid holding space 13a serves as a light shielding portion so that the light shielding portion covers the via hole. The space to be opened was opened. Next, ITO was patterned as the second transparent electrode 22b so as to cover the holding space 13a and be divided between adjacent pixels through a space of 100 μm. Subsequently, similarly to the first substrate 11, a parylene dielectric layer having a thickness of 300 nm and a surface layer 23a of a fluorinated polymer having a thickness of 100 nm were formed.

  In Example 4, as in the modification of the second embodiment, the second transparent electrode 22b is formed to cover the wall and bottom of the holding space 13a. However, as in the second embodiment, the second transparent electrode 22b is formed only on a region of the support layer 16a where the holding space 13a is not formed, or is held in the support layer 16a. It is formed only in the region where the space 13a is not formed and on the upper side of the wall portion of the holding space 13a, and may not be formed so as to cover the bottom of the holding space 13a. It is sufficient that the parylene dielectric layer and the fluorinated polymer surface layer 23a are not formed on the inner wall of the holding space 13a, and it does not depend on whether or not the second transparent electrode 22b is formed on the wall portion of the holding space 13a. In the case where the second transparent electrode 22b is not formed on the wall portion of the holding space 13a, a via hole is formed in the support layer 16a separately from the holding space 13a and connected to the source electrode of the TFT. Can be configured.

  Next, a partition wall portion 17a was formed using a white UV curable resin at a boundary portion of each pixel 15b on the support layer 16a. Subsequently, using a microcapillary dropping method, the colored conductive liquid FL4 was introduced into the holding space 13b of the pixel 15b, and oil FL3 was filled thereon. This operation was repeated so that the three color conductive liquids FL4 were regularly arranged. This was aligned and bonded to the surface layer 23 c side of the first substrate 11.

  A nano silver ink was printed and formed on the third substrate 41 by an ink jet method and dried to form the gate electrode 42. Next, the heat insulation type polyimide was applied using a spin coat method, and heat treatment was performed to form the gate insulating film 43. Next, the organic semiconductor layer 44 was formed by dissolving the organic semiconductor material represented by the structural formula of Formula (1) in xylene by using an ink jet method to form an ink. Next, surface modification was performed by irradiating the region where the source / drain electrodes 45 and 46 were formed with ultraviolet rays through a photomask. Furthermore, the nano / silver ink was formed by printing using an ink jet method and dried to form source / drain electrodes 45 and 46. An organic TFT was obtained by covering the upper surface with a protective layer made of an insulating polymer.

得られた有機ＴＦＴのソース電極４５と第２の基板１２のビアホール４８との間で位置
合わせを施し、異方性導電接着フィルム（ＡＣＦ）４７を介してこれらを貼り合せること
で、表示素子４０を得た。有機ＴＦＴを適宜駆動することで、明るく応答性に優れたカラー表示性能を確認した。

Position alignment is performed between the source electrode 45 of the obtained organic TFT and the via hole 48 of the second substrate 12, and these are bonded via an anisotropic conductive adhesive film (ACF) 47, whereby the display element 40. Got. By appropriately driving the organic TFT, it was confirmed that the color display performance was bright and excellent in responsiveness.

  The preferred embodiments of the present invention have been described above, but the present invention is not limited to such specific embodiments, and various modifications can be made within the scope of the gist of the present invention described in the claims. Can be modified or changed.

10, 10a, 10b, 30, 40 Display element 11 First substrate 12 Second substrate 13, 13a, 13b Holding space 14 Display space 15, 15a-15e Pixel 16, 16a Support layer 17, 17a Partition portion 20, 20a, 20b Fluid moving means 21 First transparent electrodes 22, 22a, 22b Second transparent electrodes 23, 23a, 23b Surface layer 24 Second surface layers 31, 31a-31c Color filter 41 Third substrate 42 Gate electrode 43 Gate insulating film 44 Organic semiconductor layer 45 Source electrode 46 Drain electrode 47 Adhesive layer 48 Via hole 49 Through electrode FL1, FL3 First fluid FL2, FL4 Second fluid D Diameter P Pitch

Special table 2007-500876 gazette International Publication No. 06/104182

R. Hayes, A. Giraldo, F. Li and J. Feenstra, Proceedings of The 15th International Display Workshops IDW '08, pp. 233-236 (2008).

Claims (6)

A holding space is formed between two opposing substrates and holds two types of fluids that are not mixed with each other, and a voltage is applied between the two substrates across the holding space to supply the two types of fluids. A display element having fluid moving means for moving to two different states,
A partition for dividing the holding space;
The fluid moving means includes
A first transparent electrode formed on the second substrate side of the transparent first substrate;
A second transparent electrode formed on the first substrate side of the second substrate via a support layer,
The support layer is formed using a light-reflective photosensitive resist material,
The display element, wherein the partition wall is formed integrally with the support layer.   The display element according to claim 1, wherein the photosensitive resist material is a material containing a white inorganic pigment. The fluid moving means includes a surface layer covering a surface of the second transparent electrode;
The interface tension of the surface layer is changed by applying a voltage between the first transparent electrode and the second transparent electrode in the surface layer. The display element as described in.   The first type fluid of the two types of fluid is light transmissive, and the second type fluid is colored in a predetermined color. A display element according to any one of the above.   The display element according to claim 4, wherein the first type fluid has conductivity or polarity. The wall surface of the partition wall is covered with a second surface layer formed integrally with the surface layer,
6. The display element according to claim 4, wherein an interfacial tension of the second surface layer is larger than an interfacial tension of the surface layer.

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