JP2011007927A - Display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflective display element having a high white-reflectance and a high contrast ratio and displaying a high-quality high-definition image.SOLUTION: The display element includes a first substrate 101, a second substrate 102, a first optical switching layer 103, a second optical switching layer 104, and a driving means applying voltage to the first optical switching layer 103 and the second optical switching layer 104 to drive them independently. The first substrate 101 is a transparent substrate. The first optical switching layer 103 and the second optical switching layer 104 are layered between the first substrate 101 and the second substrate 102 in this order from the first substrate 101 side. The first optical switching layer 103 is switched between a light transmitting state and a light absorbing state. The second optical switching layer 104 is switched between a light reflecting state and a light absorbing state.

Description

  The present invention relates to a reflective display element that is non-luminous and has a low burden on the eyes, and more particularly to a color display element that has high contrast and excellent visibility of information such as images and characters.

In recent years, the demand for portable electronic devices has been increasing rapidly, and in particular, a light-weight and low-priced display element that can be used as a medium to replace paper has attracted particular attention. Such a display element is strongly expected to play an important role in society by enabling transmission / reception and reference of information without being limited by time and place.
As a characteristic required for the display element as described above, it has a high white reflectance and a contrast ratio in addition to a reflection type (non-light-emitting type) that has a low burden on eyes even when referred to for a long time. Examples include high definition display and color display.

As a conventional display element, a combination of a black and white display element with a color filter and a stack of a plurality of color display layers are known.
In general, a color filter is often used in order to realize a color display with a reflection type. For example, Patent Document 1 proposes forming a color filter in an electrophoretic display element that performs display by moving white and black charged particles dispersed in a dispersion medium. However, due to the principle of electrophoresis, it is difficult to obtain high reflectivity and high contrast unless only white particles or black particles can be brought close to the display surface. Therefore, even if a color filter is combined with such an electrophoretic display element, a high-quality display with high contrast cannot be obtained.

In Patent Documents 2 and 3, a color display sheet using an electrocapillary or an electrowetting phenomenon is proposed.
In the display sheet disclosed in Patent Document 2, a color pixel is created by selectively allowing a colored liquid and a transparent liquid enclosed between transparent sheets to enter and exit from a reservoir, and conductive R, G , It is said that full color display is possible by enclosing B ink. However, in the method described in Patent Document 2, since the element structure is complicated, it is difficult to reduce the element thickness, and as a result, a high white reflectance cannot be obtained.
Further, in the display device of Patent Document 3, the colored liquid and the transparent liquid are sealed in the space between the support plates, the colored liquid is adjacent to the support plate, and the transparent liquid is partially adjacent to the support plate. Display is performed by switching. It is said that there is a possibility of a color display by using oils colored in R, G and B. However, in the display device of Patent Document 3, it is difficult to sufficiently absorb light with a thin oil layer, and it is difficult to obtain high contrast. Further, in the display device of Patent Document 3, even in a state where the transparent liquid is adjacent to the support plate, that is, in a state of presenting a white background, a high white reflectance can be obtained in principle because the aperture ratio can be increased only to about 2/3. It was also difficult to obtain.

  The present invention has been made in view of the above problems in the prior art, and an object thereof is to provide a reflective display element having high white reflectance and contrast ratio and capable of high quality and high definition display. And

In order to solve the above problems, the display element according to the present invention specifically has the technical features described in the following (1) to (19).
(1): Voltage is applied to the first substrate, the second substrate, the first optical switching layer, the second optical switching layer, the first optical switching layer, and the second optical switching layer. Drive means for independently driving each of the first and second substrates, wherein the first substrate is a transparent substrate, and the first optical switching layer and the second optical switching layer are the first substrate. A first optical switching layer and a second optical switching layer are laminated in this order from the first substrate side between the substrate and the second substrate. The display element is switched between a transmission state and a light absorption state, and the second optical switching layer is switched between a light reflection state and a light absorption state.

  By having the configuration described in (1) above, it is possible to provide a reflective display element having a high white reflectance and a contrast ratio.

(2) The display element according to (1), wherein a transparent intermediate layer is provided between the first optical switching layer and the second optical switching layer.

(3) The display element according to (2), wherein the transparent intermediate layer includes a first transparent electrode layer.

(4) The display element according to (2), wherein a pair of first transparent electrode layers are provided between the first substrate and the transparent intermediate layer.

  With the configuration according to any one of (2) to (4), it is possible to provide a display element capable of independently driving each optical switching layer.

(5): The first optical switching layer has a plurality of pixels that can be driven independently, and each of the plurality of pixels is one of at least three primary colors capable of full color display in a light absorption state. Any one color is exhibited, It is a display element of any one of said (1) thru | or (4) characterized by the above-mentioned.

  By having the configuration described in (5) above, it is possible to provide a reflective display element capable of color display in addition to high white reflectance and contrast ratio.

(6): A transparent intermediate layer is provided between the first optical switching layer and the second optical switching layer, and the first optical switching layer has a plurality of pixels that can be driven independently. Each of the plurality of pixels includes at least a plurality of partition walls, a first fluid that does not mix with each other, and a first fluid that is contained in a holding space defined by the plurality of partition walls, the first substrate, and the transparent intermediate layer. Each of the plurality of pixels exhibits any one of at least three primary colors capable of full color display in a light absorbing state, and the transparent intermediate layer includes the first fluid. Having at least a first surface layer, a first transparent electrode layer, and a first support layer made of a light transmitting material in order from the side in contact with one fluid and / or the second fluid. Characteristic table as described in (1) above It is an element.

(7): A transparent intermediate layer provided between the first optical switching layer and the second optical switching layer, and a pair of provided between the first substrate and the transparent intermediate layer A first transparent electrode layer, and a pair of first surface layers laminated on the pair of first transparent electrode layers so as to face each other, wherein the first optical switching layer is driven independently A plurality of possible pixels, and each of the plurality of pixels is not mixed with each other contained in a holding space defined by at least a plurality of partition walls and the plurality of partition walls and the pair of first surface layers. The plurality of pixels each exhibit any one of at least three primary colors capable of full-color display in a light-absorbing state, and the transparent fluid is formed of the first fluid and the second fluid. The intermediate layer is a first support layer made of a light transmitting material. A display device according to (1), characterized in that it has.

  With the configuration described in (6) or (7) above, it is possible to provide a display element having an optical switching layer that can switch between a light transmission state and a light absorption state with a simple configuration.

(8): The first fluid has optical transparency, and the second fluid is colored in any one of at least three primary colors capable of full color display. The display element according to (6) or (7).

  With the configuration described in (8) above, it is possible to provide a display element having an optical switching layer capable of switching between a light transmission state and a predetermined color light absorption state with a simple configuration.

(9): The display element according to (8), wherein the plurality of pixels are regularly arranged for each color.

  With the configuration described in (9) above, it is possible to provide a display element that can be driven independently without mixing the fluids colored in the primary colors and can display a desired full-color image.

(10) In the above (6) to (9), the interfacial tension of the first surface layer is changed by applying a voltage to the first transparent electrode layer. It is a display element given in any 1 paragraph.

  With the configuration described in (10) above, it is possible to provide a display element having an optical switching layer that can switch between a light transmission state and a light absorption state at high speed with a simple configuration.

(11): The second optical switching layer has a plurality of pixels that can be driven independently,
Each of the plurality of pixels is white in the light reflection state and black in the light absorption state. It is a display element of any one of said (1) thru | or (10).

  With the configuration described in (11) above, a display element with a high contrast ratio can be provided.

(12): Each of the plurality of pixels is contained in a holding space defined by at least a plurality of partition walls, the plurality of partition walls, the second substrate, and the transparent intermediate layer. A fluid and a fourth fluid, and the second substrate includes at least a second surface layer in order from the side in contact with the third fluid and / or the fourth fluid, and a second surface layer. The display element according to (11) above, which has a transparent electrode layer and a second support layer made of a light reflecting material.

(13): A pair of second transparent electrode layers provided between the second substrate and the transparent intermediate layer, and a pair laminated so as to face the pair of second transparent electrode layers. Each of the plurality of pixels is contained in a holding space defined by at least a plurality of partition walls and the plurality of partition walls and the pair of second surface layers. (11), wherein the second substrate is composed of a third fluid and a fourth fluid that are not mixed, and the second substrate has a second support layer composed of a light reflecting material. It is a display element of description.

  With the configuration described in (12) or (13) above, it is possible to provide a display element having an optical switching layer that can switch between a light reflection state and a light absorption state with a simple configuration.

(14) The display element according to (12) or (13), wherein the light reflecting material is a material that exhibits white color by scattering external light.

  By having the configuration described in (14) above, it is possible to provide a display element capable of white display with good visibility.

(15) In any one of the above (12) to (14), the light reflecting material is formed using a photoresist material whose physical properties are changed by irradiation with a light beam or an electron beam. It is a display element of description.

  By having the structure as described in said (15), the display element which can be manufactured with a simple process and was excellent in intensity | strength can be provided.

(16) In any one of the above (12) to (15), the third fluid is light transmissive and the fourth fluid is colored black. It is a display element of description.

  By having the structure as described in said (16), the display element which has an optical switching layer which can switch a white display and a black display with a simple structure can be provided.

(17): In the above (12) to (16), the second surface layer has an interfacial tension of the second surface layer changed by applying a voltage to the second transparent electrode layer. It is a display element given in any 1 paragraph.

  By having the structure as described in said (17), the display element which has an optical switching layer which can switch a light reflection state and a light absorption state at high speed with a simple structure can be provided.

(18): The first transparent electrode layer and the second transparent electrode layer are both provided corresponding to each of the plurality of pixels, and are electrically separated for each pixel. The display element according to any one of (12) to (17), wherein the display element is characterized.

  By having the configuration described in (18) above, it is possible to provide a display element capable of independently driving each pixel by connecting separate parts to each divided part.

(19): The plurality of pixels included in the first optical switching layer and the plurality of pixels included in the second optical switching layer have the same pitch and are regularly arranged in a matrix. The display element according to any one of (11) to (18), wherein the display elements are arranged in the vertical direction of the first substrate.

  By having the structure as described in said (19), a three-color display state can be exhibited by each pixel, and a color display element with high display quality can be provided.

  According to the present invention, it is possible to provide a reflective display element having a high white reflectance and a contrast ratio and capable of high quality and high definition display.

It is a schematic sectional drawing which shows the basic composition in 1st Embodiment of the display element which concerns on this invention. It is a schematic sectional drawing which shows the structure of the 1st optical switching layer 3 in 1st Embodiment of the display element which concerns on this invention. It is a schematic sectional drawing which shows the structure of the 2nd optical switching layer 4 in 1st Embodiment of the display element which concerns on this invention. It is a schematic sectional drawing which shows the structure of the 1st optical switching layer 13 in 2nd Embodiment of the display element which concerns on this invention. It is a schematic sectional drawing which shows the structure of the 2nd optical switching layer 14 in 2nd Embodiment of the display element which concerns on this invention. 2 is a schematic cross-sectional view showing a configuration of a color display element of Example 1. FIG. 6 is a schematic cross-sectional view showing a configuration of a color display element of Example 2. FIG. 6 is a schematic cross-sectional view showing a configuration of a first optical switching layer 203 in the color display element of Example 2. FIG. 6 is a schematic cross-sectional view illustrating a configuration of a color display element of Example 3. FIG. 6 is a schematic cross-sectional view illustrating a configuration of a color display element of Example 4. FIG.

The present invention is higher than before by laminating a first optical switching layer that switches between a light transmission state and a light absorption state and a second optical switching layer that switches between a light reflection state and a light absorption state. It has been experimentally found that a reflective display element having a white reflectance and a contrast ratio can be produced, and has been completed.
That is, the display element according to the present invention includes a first substrate 1, a second substrate 2, a first optical switching layer 3, a second optical switching layer 4, and the first optical switching layer 3. Driving means for applying a voltage to the second optical switching layer 4 to independently drive the second optical switching layer 4, the first substrate 1 being a transparent substrate, and the first optical switching layer 3. And the second optical switching layer 4 includes a first optical switching layer 3 and a second optical switching between the first substrate 1 and the second substrate 2 from the first substrate side 1. The first optical switching layer 3 is switched between a light transmission state and a light absorption state, and the second optical switching layer 4 is switched between a light reflection state and a light absorption state. It is characterized by switching.

Next, the display element according to the present invention will be described in more detail.
Although the embodiments described below are preferred embodiments of the present invention, various technically preferable limitations are attached thereto, but the scope of the present invention is intended to limit the present invention in the following description. Unless otherwise described, the present invention is not limited to these embodiments.

[First Embodiment]
FIG. 1 is a schematic sectional view showing a basic configuration of a display device according to a first embodiment of the present invention.
In the display element according to the present embodiment, two optical switching layers (3, 4) are laminated between a first transparent substrate (first substrate) 1 and a second substrate 2. More specifically, the first optical switching layer 3 located on the transparent substrate side 1 is in a light transmitting state and a light absorbing state, and the second optical switching layer 4 located on the second substrate 2 side is in a light reflecting state and light. It has the structure which switches to an absorption state, respectively. With this configuration, when the first optical switching layer 3 is in a light transmitting state and the second optical switching layer 4 is in a light reflecting state, the reflected color of external light by the second optical switching layer 4 is changed to the first optical switching layer. When 3 is in the light transmission state and the second optical switching layer 4 is in the light absorption state, the color tone according to the absorption wavelength of the second optical switching layer 4 is absorbed. When the first optical switching layer 3 is in the light absorption state, the absorption is performed. A color tone according to the wavelength can be presented. For this reason, it is desirable that the first transparent electrode 5b (or the transparent intermediate layer 5 provided with the same) exists between the two optical switching layers (3, 4). Thereby, since the states of the first and second optical switching layers (3, 4) can be switched independently, it is possible to create three display states per unit area as described above.

Further, the first optical switching layer 3 includes a plurality of pixels exhibiting three primary colors capable of full color, specifically, cyan, magenta, yellow or red, green, and blue, so that a color display element can be configured. .
More specifically, the first optical switching layer 3 is not limited in its means as long as it can switch between transmission and absorption of light. For example, electrowetting, electrophoresis, electrochromic, cholesteric liquid crystal, etc. Each method can be applied.

  As materials for the first transparent substrate 1 and the intermediate layer 5, it is preferable to select compatible materials from glass, various plastic substrates, or the like according to the type of the optical switching layer (3, 4) to be used.

The second optical switching layer 4 is most preferable because it has a configuration in which white is displayed in the light reflection state and black is displayed in the light absorption state, thereby enabling higher-contrast display. As used herein, white and black are sufficient as long as they are generally included within the range of brightness that humans can visually recognize, and are colored by strong reflection or absorption at some specific wavelengths. However, ideally, a higher quality display can be realized by using a material that uniformly reflects or absorbs external light in the visible light region. In particular, with respect to a white material, by using a material that scatters external light, it is possible to obtain a display element that has a display quality more similar to that of paper and is less tiring.
The second optical switching layer 4 is not particularly limited as long as it is a material capable of switching between reflection and absorption of light, that is, white display and black display, and polymer dispersed liquid crystal, electrowetting, electrophoresis Each method such as twist ball and electrodeposition can be applied.

Next, the configuration of the first optical switching layer 3 in the present embodiment will be described in more detail.
FIG. 2 is a schematic cross-sectional view showing the configuration of the first optical switching layer 3 in the first embodiment of the display element according to the present invention.
As the first optical switching layer 3, an element utilizing an electrowetting phenomenon can be suitably applied. The first optical switching layer 3 includes a fluid (3a, 3b) in a unit pixel constituted by the first transparent substrate 1, the transparent intermediate layer 5, and the partition 3c (which is a part of the first optical switching layer). ) And a first fluid 3a and a second fluid 3b that are not mixed with each other.
Here, “does not mix with each other” means that the display elements are separated from each other under the conditions for use as a display element, and in particular, one is dispersed in a number of locations in the other. It is preferable that it is in a state of being separated with 1 or 2 continuous interfaces.

  As shown in FIG. 2, the transparent intermediate layer 5 has at least a first surface layer 5a, a first transparent electrode layer 5b, and a first support layer 5c made of a light transmitting material. A transparent electrode layer may be further laminated on the second substrate 2 side of the first transparent substrate 1. Further, a transparent electrode layer may be further laminated on the transparent intermediate layer 5 on the second substrate 2 side.

  The partition walls 3c between the pixels are formed by patterning using a material that meets the purpose of preventing mixing of fluids in adjacent holding spaces using photolithography or a conventionally known printing method. The partition 3c (and a partition 4c described later) partitions the above-described holding space, and can be appropriately provided according to the shape of the unit pixel. For example, in the case of a square pixel, a holding space may be formed by providing four partition walls 3c around the square pixel. In any case, a partition wall may be provided at the boundary between adjacent pixels.

  The first surface layer 5a included in the transparent intermediate layer 5 is preferably water-repellent, and a fluororesin is preferably used. Specifically, Cytop resin manufactured by Asahi Glass Co., Teflon (registered trademark) manufactured by DuPont, or a perfluorinated polymer deposited by sputtering or a gas phase reaction method is suitable. Further, the surface layer such as the first surface layer 5a and the second surface layer 2a described later may have a multilayer structure in which the resin is stacked on a transparent insulating material such as parylene.

The first transparent electrode layer 5b is formed of various materials including indium tin oxide (ITO).
For the first support layer 5c made of a light-transmitting material, a suitable material should be selected and used in consideration of various conditions such as the structure of the optical switching layer (3, 4) and the manufacturing process. Can do.

  In the configuration example of the first optical switching layer 3 in the first embodiment shown in FIG. 2, the first fluid 3a is a transparent fluid showing conductivity or polarity, and for example, water or alcohol is used. it can. The second fluid 3b is obtained by coloring a fluid that is not mixed with the first fluid 3a, and a silicone oil, hydrocarbon oil, fluorocarbon oil, or the like containing a dye can be used. Full color display is possible by regularly arranging the pixels that hold the oil colors as three complementary colors capable of creating a color spectrum, such as cyan, magenta, and yellow.

  In the steady state (steady state), the first fluid 3a and the second fluid 3b exist in two layers, and the second fluid 3b is adjacent to the first surface layer 5a. The optical switching layer 3 exhibits the color of the second fluid 3b. When a voltage is applied here (when a voltage is applied), the second fluid 3b decreases the contact area with the first surface layer 5a by changing the interfacial tension, that is, the wettability of the first surface layer 5a. Part of the first fluid 3a is adjacent to the first surface layer 5a. Thereby, in the area where the 1st fluid 3a of the 1st optical switching layer 3 adjoins the 1st surface layer 5a, it will be in a light transmission state. By such electrical means (driving means), it is possible to reversibly switch between the light absorption state and the transmission state.

Further, the configuration of the second optical switching layer 4 in the present embodiment will be described in more detail.
FIG. 3 is a schematic sectional view showing the configuration of the second optical switching layer 4 in the first embodiment of the display element according to the present invention.
The element using the electrowetting phenomenon similar to the first optical switching layer 3 as described above can be applied to the second optical switching layer 4 in the present invention.

  The second optical switching layer 4 has a holding space for holding fluid (4a, 4b) in a unit pixel constituted by the transparent intermediate layer 5, the second substrate 2, and the partition wall 4c. Contains the third fluid 4a and the fourth fluid 4b which are not mixed with each other.

Moreover, the 2nd board | substrate 2 has the 2nd support layer 2c comprised from the 2nd surface layer 2a, the 2nd transparent electrode layer 2b, and the light reflection material, as shown in FIG.
Of course, a structure in which the light reflecting material is separately arranged on the base having the structure in which the supporting layer is made of the light transmitting material as shown in FIG. 2 is possible. A reflective material is preferred.

Furthermore, it is desirable to use a material that exhibits a white color by scattering external light as the light reflecting material. Examples of the material include high refractive index fine particles such as titanium oxide and alumina in a polymer resin. Can be used. More desirably, as the material of the second support layer 2c, a photoresist material whose physical properties are changed by irradiation with light or an electron beam is used, so that the second support layer 2c and the partition walls 4c between the pixels are formed simultaneously. . The shape and number of the partition walls 4c may be the same as those of the first optical switching layer 3 described above.
Like the process of forming the partition wall 4c later, there is less concern about the separation of the partition wall, and the partition wall 4c prevents light leakage between the pixels, so that an effect of improving the contrast ratio can be expected. The photoresist material is not particularly limited as long as conditions such as process resistance and surface smoothness are met, and among them, a white solder resist used for LED mounting is easy to apply. In the configuration example of the second optical switching layer 4 shown in FIG. 3, the third fluid 4a is a transparent liquid having conductivity or polarity, and the fourth fluid 4b is a black fluid that is not mixed with the third fluid 4a. It is desirable to use a colored one. These specific materials are the same as those of the first fluid 3a and the second fluid 3b, respectively.

(Second Embodiment)
In the present embodiment, the configurations of the first optical switching layer 13 and the second optical switching layer 14 are different from those of the first embodiment.
FIG. 4 is a schematic sectional view showing the configuration of the first optical switching layer 13 in the second embodiment of the display element according to the present invention.
The first optical switching layer 13 has a holding space for holding the fluids 13a and 13b in the unit pixel divided by the partition wall 13c. In particular, in the case of the present embodiment, the display space is composed of a display space (display portion) extending in the upper part of the holding space and a holding space (holding portion) extending in the lower part. The holding space contains a first fluid 13a and a second fluid 13b that are not mixed with each other.

In the present embodiment, as shown in FIG. 4, the transparent intermediate layer 15c is composed of a second support layer (15c) made of a light transmitting material. Moreover, in this Embodiment, it has a pair of 1st transparent electrode 15a and a pair of 1st surface layer 15b laminated | stacked so that it might oppose on this. The holding portion and the display portion are adjacent spaces, and the holding space combining them is a space defined by the partition wall 13c, the pair of first surface layers 15b, and the first support layer 15c.
Here, as described above, the holding portion is a space that extends to the upper portion of the holding space and is partitioned by the partition wall 13c, the pair of first surface layers 15b, and the display portion. On the other hand, as described above, the display unit is a space that extends to the lower part of the holding space and is partitioned by the pair of first surface layer 15b, first support layer 15c, and holding unit.

The first substrate 11 may be obtained by further laminating a transparent electrode layer on the second substrate 12 side. Further, a transparent electrode layer may be further laminated on the second substrate 12 side of the transparent intermediate layer 15.
The pair of first transparent electrodes 15a, the pair of first surface layers 15b, the transparent intermediate layer 15c, the partition walls 13c between the pixels, and the like are made of the same materials and materials as those described in the description of the first optical switching layer 3 in FIG. Can be formed by a method.

  In the configuration example of the first optical switching layer 13 in the second embodiment shown in FIG. 4, the second fluid 13 b is a fluid that exhibits conductivity or polarity and is colored in a predetermined color. The liquid 13a is a transparent fluid that does not mix with the second fluid 13b. In the steady state, since the surface of the display space (first surface layer 15b) is water repellent, the second fluid 13b exists in the holding space, and the first fluid 13a is present in the display space. Therefore, the first optical switching layer 13 is macroscopically in a light transmission state. When a voltage is applied thereto, the interfacial tension, that is, the wettability of the first surface layer 15b changes, so that the second fluid 13b spreads into the display space and the first fluid 13a moves to the holding space. To do. Thereby, the 1st optical switching layer 13 exhibits the color of the 2nd fluid 13b. By such electrical means (driving means), it is possible to reversibly switch between the light absorption state and the transmission state.

FIG. 5 is a schematic cross-sectional view showing the configuration of the second optical switching layer 14 in the second embodiment of the display element according to the present invention.
Similarly to the configuration shown in FIG. 4, the second optical switching layer 14 can also use an element configured as shown in FIG. 5.
In the present embodiment, the second substrate 12c is composed of a second support layer (12c) made of a light reflecting material. Although a configuration in which a light reflecting material is separately disposed on a base of a supporting layer made of a light transmitting material is possible, it is preferable that the supporting layer is a light reflecting material from the viewpoint of securing a higher reflectance and simplifying manufacturing. The light reflecting material used for the second support layer 12c can be formed by the same material and method as described in the explanation of the second optical switching layer 4 in FIG.

Further, in the present embodiment, the second optical switching layer 14 has a pair of second transparent electrodes 12a and a pair of second surface layers 12b laminated so as to face each other. The holding portion and the display portion are adjacent spaces, and the holding space combining them is a space defined by the partition wall 14c, the pair of second surface layers 12b, and the second support layer 12c.
Here, as described above, the holding portion extends to the upper portion of the holding space, and is a space defined by the partition wall 14c, the pair of second surface layers 12b, and the display portion. On the other hand, as described above, the display unit is a space that extends to the lower part of the holding space and is partitioned by the pair of second surface layers 12b, the second support layer 12c, and the holding unit. The pair of second transparent electrodes 12a, the pair of second surface layers 12b, the partition walls 14c between the pixels, and the like are formed by the same materials and methods as described in the description of the second optical switching layer 4 in FIG. be able to.

  In the configuration example of the second optical switching layer 14 in the second embodiment shown in FIG. 5, the fourth fluid 14 b is a fluid in which conductivity or polarity is colored black, and the third fluid 14 a. It is desirable to use a transparent fluid that does not mix with the fourth fluid 14b. In the steady state, since the surface of the display space is water repellent, the fourth fluid 14b exists in the holding space, and the third fluid 14a exists in the display space. The second optical switching layer 14 is macroscopically in a light transmitting state, and light is reflected by the second support layer 12c formed of a light reflecting material provided in the lower layer. When a voltage is applied thereto, the interfacial tension, that is, the wettability of the second surface layer 12b changes, so that the fourth fluid 14b spreads into the display space and the third fluid 14a moves to the holding space. To do. Thereby, the 2nd optical switching layer 14 exhibits the color of the 4th fluid 14b. By such electrical means (driving means), it is possible to reversibly switch between the light absorption state and the transmission state.

  Each of the first transparent electrode layer 15a and the second transparent electrode layer 12a is provided corresponding to each of a plurality of pixels, and is electrically divided for each pixel. In other words, it is electrically divided between each adjacent holding space (or its vertical position). As a specific achievement method, the first transparent electrode layer 15a and the second transparent electrode layer 12a are formed in a state where the masking material is disposed at the boundary portion of the pixel, or the first transparent electrode layer 15a and After the second transparent electrode layer 12a is formed, the boundary portion can be removed by a photolithography / etching process.

  The pixels of the first optical switching layer 13 and the second optical switching layer 14 are regularly arranged in a matrix. The first optical switching layer 13 regularly arranges sub-pixels that can present, for example, cyan, magenta, and yellow. Furthermore, the second optical switching layer 14 is also formed to have the same pitch as that of the sub-pixels, and the first optical switching layer 14 is arranged in the vertical direction (perpendicular to the first substrate, the second substrate, the transparent intermediate layer, etc.). When the switching layer 13 and the second optical switching layer 14 are arranged, each sub-pixel can display three colors of white, black, and color, and a full color display is realized.

Example 1
FIG. 6 is a schematic cross-sectional view showing the configuration of the color display element of Example 1.
Three glass substrates having a thickness of 0.7 mm were prepared as substrates to be the first substrate 101, the second substrate 102, and the first support layer 105c (support layer of the transparent intermediate layer 105).
On the first substrate 101, ITO was formed as a transparent electrode 106b with a thickness of 200 nm. On the second substrate, resin black mainly composed of carbon is coated with a thickness of 1 μm as a black layer 108 for absorbing external light, and ITO as the second transparent electrode 102b is formed thereon with a thickness. Formed at 200 nm. Furthermore, resin beads having a particle diameter of 20 μm were sprayed.

  ITO surfaces 105b and 107b were formed by patterning on both sides of the first support layer 105c (transparent intermediate layer 105) so that the front and back patterns matched. Furthermore, on ITO which is the first transparent electrode 105b, a commercially available fluorinated polymer (Cytop CTL-809M, manufactured by Asahi Glass Co., Ltd.) is dissolved in perfluorotributylamine as a solvent, and the coating conditions are set to 200 nm. The first surface layer 105a was formed by spin coating application and baking after adjusting the above. Next, a sealant is dispensed on the ITO surface 107b formed on the surface of the first support layer 105c on the second substrate 102 side, leaving an injection port around the portion to be the display portion, and then the second substrate. An empty cell (holding space) was created by bonding the ITO surface (second transparent electrode) 102b formed on 102 to face the ITO surface and curing the sealant.

After encapsulating a precursor material which is a mixture of a liquid crystal composition for PDLC, a monomer composition, and a polymerization initiator in this cell, from the transparent intermediate layer 105 side, a high-pressure mercury lamp is used to focus on a wavelength of 365 nm, irradiation light intensity of 50 mW. The second optical switching layer 104 made of PDLC was formed by irradiating UV light of / cm ² for 2 minutes.

  On the first surface layer 105a, a polymer insulating material (polyimide) was transferred and dried by a screen printing method to form a partition wall 103c defining a pixel boundary. At the time of printing, alignment is performed in advance so that the ITO pattern (first transparent electrode 105b) formed in the pixel region on the transparent intermediate layer 105 overlaps the pixel region partitioned by the partition wall 103c.

  As fluids used for the first optical switching layer 103, water and alkane oils (dodecane) colored with nonpolar dyes exhibiting cyan, magenta, and yellow were prepared. First, each color of oil was poured into each pixel. Subsequently, water is injected, and the first optical switching layer in which two kinds of fluids are sealed is bonded and fixed to the transparent intermediate layer 105 so that the ITO surface (transparent electrode) 106b of the first substrate 101 is inside. 103 was formed.

  The first optical switching layer 103 of the color display element obtained by the above procedure exhibits the color of the dye in a steady state and transmits light in a voltage applied state. The second optical switching layer 104 exhibits white in a steady state, and light is transmitted and absorbed by the underlying black layer 108 in a voltage applied state, so that black is presented. It was confirmed that good color display characteristics can be obtained by appropriately applying a voltage to desired portions of the two optical switching layers 103 and 104.

(Example 2)
FIG. 7 is a schematic cross-sectional view showing the configuration of the color display element of Example 2.
Three glass substrates having a thickness of 0.7 mm were prepared as substrates to be the first substrate 201, the second substrate 202, and the first support layer 205c (support layer of the transparent intermediate layer 205).

  As an electrophoretic dispersion liquid used for the first optical switching layer 203, a cyan particle dispersion liquid is prepared by mixing charged particles colored cyan in silicone oil at a predetermined ratio and dispersing by ultrasonic treatment for one hour. Got. Similarly, magenta yellow particle dispersions were also prepared.

  A conductive liquid in which a predetermined amount of a black pigment is dispersed and an alkane-based oil (dodecane) were prepared as fluids that are not mixed with each other and used for the second optical switching layer 204.

  On the second substrate 202, a white sheet having a thickness of 100 μm made of a mixture of PET resin and titanium oxide fine particles is pasted and fixed, and the second transparent electrode 202b (lower side) is formed on a portion where ITO becomes a pixel. Then, patterning was formed with a thickness of 200 nm. Next, excimer laser processing was applied to the portion corresponding to the fluid holding space of each pixel to open cylindrical holes in the white sheet. Subsequently, parylene was formed as a dielectric layer with a thickness of 500 nm by chemical vapor deposition, and a fluorinated polymer (Cytop CTL-809M, manufactured by Asahi Glass Co., Ltd.) was dissolved in perfluorotributylamine as a solvent. The resulting surface was spin-coated and baked to form a water repellent second surface layer 202a having a thickness of 100 nm.

  The first support layer 205c was formed by patterning ITO on both sides. The ITO pattern (first transparent electrode) 205b on the upper surface side has a configuration in which each pixel portion is divided into two regions having different areas. Of the two divided regions, one has a smaller area than the other, and the smaller ITO pattern 205b is one fifth of the larger ITO pattern 205b in area ratio.

  The ITO pattern on the lower surface side (the upper side of the second transparent electrode 205b) was adjusted so that the pattern would match the lower side of the second transparent electrode 202b when facing the second substrate 202. On the first substrate 201, when facing the transparent intermediate layer 205, a pattern of the black matrix 209 is formed so as to overlap the smaller one of the ITO patterns (first transparent electrodes) 205 b on the upper surface. Keep it. Using a resist in which titanium black is dispersed as a black matrix material, a photolithography method was used.

After that, a 50 μm spacer was sprayed on the upper surface side of the transparent intermediate layer 205, and a white UV curable adhesive was dispensed on the boundary portion of each pixel to form a partition wall 203c. Next, the first substrate 201 was aligned and then bonded, and the adhesive was cured to produce a cell (holding space).
A first optical switching layer (electrophoretic layer) that can be switched by electrophoresis of colored particles by sequentially injecting the particle dispersion liquid of each color into the cell from an injection port formed in advance at each pixel end. ) 203 was obtained.

  A partition wall 204c was formed using a white UV curable resin at a boundary portion of each pixel on the second surface layer 202a. Subsequently, a black conductive liquid was introduced into the holding space of the pixel using a microcapillary, and oil (dodecane) was filled thereon. A second optical switching layer (electrowetting layer) that can be switched by an electrowetting phenomenon by aligning and bonding the first optical switching layer 203 to the transparent intermediate layer 205 side. A laminated structure of 204 and a first optical switching layer (electrophoresis layer) 203 was formed.

  The first optical switching layer 203 of the color display element obtained by the above procedure applies a voltage to the smaller one of the ITO patterns (first transparent electrodes) 205b formed on the upper surface of the transparent intermediate layer 205. In the applied state, the colored particles are not visually recognized and are macroscopically light-transmitting (see FIG. 8 (1)). On the other hand, in a state where a voltage is applied to the larger area of the ITO pattern (first transparent electrode) 205b, the colored particles spread on the ITO, and each pixel presents the color of the enclosed colored particles (FIG. 8). (See (2)). The second optical switching layer 204 exhibits white in a steady state, and exhibits black when the black conductive liquid wets and spreads in the display space in a voltage applied state. It was confirmed that good color display characteristics can be obtained by appropriately applying voltages to desired portions of the two optical switching layers 203 and 204.

(Example 3)
FIG. 9 is a schematic cross-sectional view showing the configuration of the color display element of Example 3.
Three glass substrates having a thickness of 0.7 mm were prepared as substrates to be the first substrate 301, the second substrate 302, and the first support layer 305c (support layer of the transparent intermediate layer 205).

As an electrochromic material used for the first optical switching layer 303, a terephthalic acid compound that develops cyan, magenta, and yellow when a voltage is applied was prepared and dissolved in ethanol. By adding and dispersing TiO ₂ nanoparticles in each solution, the electrochromic material was adsorbed on the surface of the particles to form a dispersion of the electrochromic composite material, and a small amount of surfactant was added.

As a fluid used for the second optical switching layer 304, water and alkane oil (dodecane) colored with a nonpolar dye exhibiting black color were prepared.
An ITO surface 306b was formed on the first substrate 301 as a transparent electrode. On the second substrate 302, a negative type light-scattering photoresist (PSR-4000, manufactured by Taiyo Ink Manufacturing Co., Ltd.) is applied, and development processing is performed after UV exposure under predetermined conditions in a state where a pixel portion is masked. And a structure in which the pixel portion of the photoresist material was concave was obtained. Next, ITO as the second transparent electrode 302b was formed by patterning so as to be formed on the pixel portion. Subsequently, parylene was formed as a dielectric layer with a thickness of 300 μm by chemical vapor deposition, and a fluorinated polymer (Cytop CTL-809M, manufactured by Asahi Glass Co., Ltd.) was dissolved in perfluorotributylamine as a solvent. A 100 nm thick water-repellent second surface layer 302a was formed by spin coating and baking.

  Patterning was performed so that the ITO surfaces 305b and 307b were formed on portions that would become pixels so that the front and back patterns would match on both surfaces of the first support layer 305c. A partition wall 303c was formed by transferring and curing a polymer material containing a light-shielding material by a printing method at a boundary portion between the pixels on the upper surface side (first substrate 301 side). Subsequently, a dispersion liquid of electrochromic composite material prepared in advance, one color per pixel, was applied to each pixel portion by an ink jet method to form an electrochromic layer (first optical switching layer) 303. .

  After injecting water and alkane oil (dodecane) colored with a nonpolar dye exhibiting a black color onto each pixel on the second surface layer 302a, it is bonded and fixed facing the lower surface side of the transparent intermediate layer 305. Thus, a second optical switching layer (electrowetting layer) 304 enclosing two kinds of fluids was formed.

  The second optical switching layer 304 having the electrochromic layer (first optical switching layer) 303 on the upper surface, obtained by the above procedure, and the first substrate 301 are opposed to each other with a spacer having a thickness of 20 μm. Fixed. In a space between the electrochromic layer 304 and the first substrate 301, a liquid electrolyte (tetrabutylammonium perchlorate propylene carbonate solution) is sealed to form an electrolyte layer, and the periphery is sealed, A laminated structure of the first optical switching layer 303 and the second optical switching layer 304 could be obtained.

  The first optical switching layer 303 of the color display element obtained by the above procedure transmits light when no voltage is applied, and presents a color corresponding to the absorption wavelength of each electrochromic material when a voltage is applied. The second optical switching layer 304 exhibits black in a steady state and exhibits white of the light scattering resist on the second substrate 302 in a voltage application state. It was confirmed that good color display characteristics can be obtained by appropriately applying voltages to desired portions of the two optical switching layers 303 and 304.

Example 4
FIG. 10 is a schematic cross-sectional view showing the configuration of the color display element of Example 4.
The first substrate 401, the second substrate 402, the third substrate 405c2, the fourth substrate 405c3, the first support layer 405c1 that is the fifth substrate, and the sixth substrate 419 have a thickness of 0. Six pieces of 7 mm glass substrates were prepared.
As fluids that are not mixed with each other used in the first optical switching layer 403, three kinds of conductive liquids in which a predetermined amount of cyan, magenta, and yellow pigments are dispersed and a transparent alkane oil (dodecane) were prepared. A conductive liquid in which a predetermined amount of black pigment is dispersed and an alkane-based oil (dodecane) were prepared as fluids that are not mixed with each other and used for the second optical switching layer 304.

  On the fourth substrate 405c3 constituting the first substrate 401 and the transparent intermediate layer 405, ITO (a lower portion of the first transparent electrode 402b and a lower portion of the second transparent electrode 405b) is formed in a portion to be a pixel. After patterning as described above, parylene was formed as a dielectric layer by a chemical vapor deposition method to a thickness of 300 μm, and a fluorinated polymer (Cytop CTL-809M, manufactured by Asahi Glass Co., Ltd.) was used as a solvent. A solution dissolved in fluorotributylamine was spin-coated and baked to form a water-repellent first surface layer 405a (upper part) and a second surface layer 402a (upper part) each having a thickness of 100 nm.

  As a part of the second substrate 402 and a part of the first support layer 405c1 which is a fifth substrate constituting the transparent intermediate layer 405, a conductive material (silver paste) is previously placed in a place to be a fluid holding space of the pixel. ) Filled via holes 411 and 411 ′ having a diameter of 50 μm were prepared.

  Next, a transparent thick film resist is applied on a part of the first support layer 405c1, UV exposure is performed in a state where a part that becomes a fluid holding space is shielded by a negative mask, and development is performed to hold each pixel. A space serving as a space was opened to produce a first support layer 405c1 that was a fifth substrate. Next, ITO was formed as a first transparent electrode 405b (lower part) in a portion to be a pixel, and was patterned to be divided between adjacent pixels. Subsequently, parylene was formed as a dielectric layer with a thickness of 500 nm by chemical vapor deposition, and a fluorinated polymer (Cytop CTL-809M, manufactured by Asahi Glass Co., Ltd.) was dissolved in perfluorotributylamine as a solvent. The water-repellent first surface layer 405a (lower part) having a thickness of 100 nm was formed by spin coating application and baking. A partition wall 403c was formed using a white UV curable resin (PSR-4000, manufactured by Taiyo Ink Manufacturing Co., Ltd.) at the boundary portion of each pixel on the first surface layer 405a.

  Subsequently, the colored conductive liquid is introduced into the pixel holding space formed by the first support layer 405c1 (and the lower portion of the first surface layer 405a stacked thereon) and the partition 403c using a microcapillary. And filled with oil. This operation was repeated so that the three color conductive liquids were regularly arranged. This was aligned and bonded to the first surface layer 405a laminated on the first substrate 401.

ITO serving as a gate electrode 415 was formed on a third substrate 405c2 constituting a part of the transparent intermediate layer 405, and a SiON gate insulating film 418 was formed by sputtering with a thickness of 300 nm. Further, a-InGaZnO (416) that is an oxide semiconductor material was patterned by sputtering, and then ITO was patterned as the source electrode 414 and the drain electrode 413. A protective layer 417 made of SiON was formed on the upper surface of a-InGaZnO (416). As a result, a bottom gate type transparent TFT was obtained.
By aligning the source electrode 413 on the obtained TFT and the via hole 411 portion of the fifth substrate 405c1, and bonding them through the transparent anisotropic conductive adhesive sheet 412, the first optical switching layer 403 is obtained. Got.

  Further, a white thick film resist is coated on a part of the second substrate 402 described above, and UV exposure is performed in a state where a portion serving as a fluid holding space is shielded with a negative mask, and then development is performed and held in each pixel. A second substrate 402 was manufactured by opening a space serving as a work space. Next, ITO was formed as a second transparent electrode 402b (lower part) in a portion to be a pixel, and was patterned to be divided between adjacent pixels. Subsequently, parylene was formed as a dielectric layer with a thickness of 500 μm by chemical vapor deposition, and a fluorinated polymer (Cytop CTL-809M, manufactured by Asahi Glass Co., Ltd.) was dissolved in perfluorotributylamine as a solvent. The water-repellent second surface layer 402a (lower part) having a thickness of 100 nm was formed by spin coating and baking. A partition wall 404c was formed using a white UV curable resin (PSR-4000, manufactured by Taiyo Ink Manufacturing Co., Ltd.) at the boundary portion of each pixel on the second surface layer 402a.

  Subsequently, a conductive liquid in which a black pigment is dispersed using a microcapillary is formed into a pixel holding space formed by a second substrate (and a lower portion of the second surface layer 402a stacked thereon) and a partition 404c. And filled with oil. This was aligned and bonded to the second surface layer 402a side of the fourth substrate 405c3.

  On the sixth substrate 419, nano silver ink was printed and dried by an inkjet method to form a gate electrode 415 '. Next, a gate insulating film 418 ′ was formed by applying a heat-polymerizable polyimide using a spin coating method and performing heat treatment. Surface modification was performed by irradiating the region where the source electrode 414 ′ and the drain electrode 413 ′ are formed with ultraviolet rays through a photomask. Furthermore, nano silver ink was printed by an ink jet method and dried to form a source electrode 414 'and a drain electrode 413'.

  Next, an organic semiconductor layer 416 ′ is formed by forming an ink film by dissolving an organic semiconductor material represented by the structural formula of the following formula 1 in xylene using an inkjet method, An organic TFT was obtained by covering the upper surface with a protective layer 417 ′ made of an insulating polymer (polyimide).

  By aligning the source electrode 413 ′ of the obtained TFT and the via hole 411 ′ portion of the second substrate 402, and bonding them through an anisotropic conductive adhesive sheet (ACF) 412 ′, the second electrode An optical switching layer 404 was obtained.

  The first optical switching layer 403 and the second optical switching layer 404 were stacked and fixed so that each pixel was aligned in the vertical direction (in the vertical direction of each substrate), whereby a color display element could be obtained. It was confirmed that by driving the two transistors, bright and excellent display characteristics can be obtained.

  According to Examples 1 to 4 described above, a color display element having a high white reflectance and a contrast ratio and capable of high-quality and high-definition display was obtained.

DESCRIPTION OF SYMBOLS 1,11 1st board | substrate 2,12 2nd board | substrate 2a, 12a 2nd surface layer 2b, 12b 2nd transparent electrode layer 2c, 12c 2nd support layer 3,13 1st optical switching layer 3a, 13a First fluid 3b, 13b Second fluid 3c, 13c Bulkhead 4, 14 Second optical switching layer 4a, 14a Third fluid 4b, 14b Fourth fluid 4c, 14c Bulkhead 5, 15 Transparent intermediate layer 5a , 15a First surface layer 5b, 15b First transparent electrode layer 5c, 15c First support layer

JP 2003-161964 A Japanese Patent No. 3831474 JP 2005-517993 A

Claims (19)

A voltage is applied to each of the first substrate, the second substrate, the first optical switching layer, the second optical switching layer, the first optical switching layer, and the second optical switching layer. Driving means for independently driving, and
The first substrate is a transparent substrate;
The first optical switching layer and the second optical switching layer are arranged between the first substrate and the second substrate from the first substrate side, the first optical switching layer, the second optical switching layer, Laminated in the order of the optical switching layer,
The first optical switching layer switches between a light transmission state and a light absorption state,
The display element, wherein the second optical switching layer is switched between a light reflection state and a light absorption state.   The display element according to claim 1, further comprising a transparent intermediate layer between the first optical switching layer and the second optical switching layer.   The display element according to claim 2, wherein the transparent intermediate layer includes a first transparent electrode layer.   The display element according to claim 2, further comprising a pair of first transparent electrode layers between the first substrate and the transparent intermediate layer. The first optical switching layer has a plurality of pixels that can be driven independently,
5. The display element according to claim 1, wherein each of the plurality of pixels exhibits any one of at least three primary colors capable of full color display in a light absorption state. 6. . A transparent intermediate layer is provided between the first optical switching layer and the second optical switching layer,
The first optical switching layer has a plurality of pixels that can be driven independently,
Each of the plurality of pixels includes at least a plurality of partition walls, a first fluid that is not mixed with each other, and a second fluid that is contained in a holding space defined by the plurality of partition walls, the first substrate, and the transparent intermediate layer. A fluid, and
Each of the plurality of pixels exhibits any one of at least three primary colors capable of full color display in a light absorption state,
The transparent intermediate layer is composed of at least a first surface layer, a first transparent electrode layer, and a light transmitting material in order from the side in contact with the first fluid and / or the second fluid. The display element according to claim 1, further comprising: a support layer. A transparent intermediate layer provided between the first optical switching layer and the second optical switching layer;
A pair of first transparent electrode layers provided between the first substrate and the transparent intermediate layer;
A pair of first surface layers laminated so as to face the pair of first transparent electrode layers,
The first optical switching layer has a plurality of pixels that can be driven independently,
The plurality of pixels respectively include a first fluid and a second fluid that are not mixed with each other and are contained in a holding space defined by at least a plurality of partition walls and the plurality of partition walls and the pair of first surface layers. And consists of
Each of the plurality of pixels exhibits any one of at least three primary colors capable of full color display in a light absorption state,
The display element according to claim 1, wherein the transparent intermediate layer has a first support layer made of a light transmitting material. The first fluid has optical transparency,
The display element according to claim 6 or 7, wherein the second fluid is colored in any one of at least three primary colors capable of full color display.   The display element according to claim 8, wherein the plurality of pixels are regularly arranged for each color.   10. The first surface layer according to claim 6, wherein an interfacial tension of the first surface layer is changed by applying a voltage to the first transparent electrode layer. 11. Display element. The second optical switching layer has a plurality of pixels that can be driven independently,
Each of the plurality of pixels is white in the light reflection state and black in the light absorption state. The display element according to claim 1. Each of the plurality of pixels includes at least a plurality of partition walls, a third fluid that is not mixed with each other, and a fourth fluid that is contained in a holding space defined by the plurality of partition walls, the second substrate, and the transparent intermediate layer. A fluid, and
The second substrate is composed of at least a second surface layer, a second transparent electrode layer, and a light reflecting material in order from the side in contact with the third fluid and / or the fourth fluid. The display element according to claim 11, further comprising: a second support layer. A pair of second transparent electrode layers provided between the second substrate and the transparent intermediate layer;
A pair of second surface layers laminated so as to face the pair of second transparent electrode layers,
Each of the plurality of pixels includes a third fluid and a fourth fluid which are not mixed with each other and are contained in a holding space defined by at least a plurality of partition walls and the plurality of partition walls and the pair of second surface layers. And consists of
The display element according to claim 11, wherein the second substrate has a second support layer made of a light reflecting material.   The display element according to claim 12, wherein the light reflecting material is a material that exhibits white color by scattering external light.   The display element according to claim 12, wherein the light reflecting material is formed using a photoresist material whose physical properties are changed by irradiation with a light beam or an electron beam. The third fluid is light transmissive;
The display element according to claim 12, wherein the fourth fluid is colored black.   17. The second surface layer according to any one of claims 12 to 16, wherein an interfacial tension of the second surface layer is changed by applying a voltage to the second transparent electrode layer. Display element.   The first transparent electrode layer and the second transparent electrode layer are both provided corresponding to each of the plurality of pixels, and are electrically divided for each pixel. Item 18. The display element according to any one of Items 12 to 17.   The plurality of pixels included in the first optical switching layer and the plurality of pixels included in the second optical switching layer have the same pitch and are regularly arranged in a matrix, and each other The display element according to claim 11, wherein the display elements are arranged in the vertical direction of one substrate.

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