WO2015045398A1

WO2015045398A1 - Electrochromic display panel

Info

Publication number: WO2015045398A1
Application number: PCT/JP2014/004922
Authority: WO
Inventors: 佐藤　和仁
Original assignee: 凸版印刷株式会社
Priority date: 2013-09-27
Filing date: 2014-09-25
Publication date: 2015-04-02
Also published as: TW201516549A; JPWO2015045398A1

Abstract

Provided is an electrochromic display panel in which enlargement of pixel color surface area can easily be controlled without losing reflectivity and image quality. The electrochromic display panel is provided with a substrate on which part of a layered structure is formed by data lines (3a) extending in a first direction and scanning lines (1a) extending in a second direction crossing the data lines (3a) as well as pixel electrodes (6a) and thin film transistors (20) which are disposed so as to correspond to a crossing area of the data lines (3a) and the scanning lines (1a). The electrochromic display panel is also provided with shield electrodes (12a) that cover the data lines (3a) and scanning lines (1a) from above and are formed with a width 2 - 4 µm wider than the data lines (3a) and the scanning lines (1a).

Description

Electrochromic display panel

The present invention relates to an electrochromic display panel, and more particularly to an electrochromic display panel in which a shield electrode is disposed between pixels and a manufacturing method thereof.

In recent years, liquid crystal using a backlight as an information display panel has been mainstream. However, the burden on the eyes is large, and it is not suitable for applications that keep watching for a long time.

Therefore, as a reflective display device with a small eye load, a display panel having a pair of opposed electrodes and an electrophoretic display layer provided between the electrodes has been proposed as an electrophoretic display device ( Patent Document 1).

This electrophoretic display panel displays characters and images by reflected light, similar to the printed paper, and is suitable for work that keeps the screen looking for a long time with little load on the eyes.

However, the white reflectance of the electrophoretic display medium that changes the reflectance by moving the white and black charged particles is not sufficiently high due to the influence of the black charged particles. Therefore, there is a demand for a reflective display panel having a high reflectance according to another method.

As one of them, an electrochromic display method that uses an electrochromic material that can be electrically changed in color and has a simple structure with a small number of layers is attracting attention.

On the other hand, in the electrochromic method in which there is no clear voltage threshold, there is a problem that the color pixel area is expanded due to the spread of the electric field between the electrodes.

Therefore, as an electrochromic driving method, a method in which the display electrode and the counter electrode are arranged on the same plane (see Patent Document 2), or a passive driving method in which the display electrode and the counter electrode are arranged to face each other at 90 degrees. (See Patent Document 3), a matrix driving method (see Patent Document 4) in which an active element is arranged for each pixel as a counter electrode has been proposed. However, any of the driving methods causes the above-described problem. It is said that high-quality display is difficult with this method.

In order to solve this problem, a proposal has been made to suppress the spread of the electric field by forming vertical porous partition walls in the electrolyte layer (see Patent Document 5).

However, when a vertical porous structure barrier rib is formed, sufficient electrolyte does not reach the electrochromic layer adjacent to the barrier rib portion, and the rate of color change and the color density become uneven, resulting in poor reflectance and image quality. It will cause a decline. Furthermore, microfabrication such as the partition walls described above has low mass productivity and is not practical.

Also, a proposal has been made to prevent the influence of an electric field on adjacent pixels by forming partition walls in units of pixels in order to suppress the spread of pixels (Patent Document 6).

However, it did not suppress the spread of the electric field itself.

Japanese Patent Publication No. 50-015115 JP 2006-323191 A JP 2012-168439 A JP 2002-287173 A JP 2008-033083 A JP 2010-224240 A

As described above, in order to improve the expansion of the pixel coloring area due to the spread of the electric field, there is a proposal of constructing a partition wall having a vertical porous structure in the electrolyte layer. However, when such a proposal is made and driven, sufficient electrolyte does not reach the electrochromic layer adjacent to the partition wall, resulting in uneven color change speed and color density, resulting in a decrease in reflectance and image quality. Will be invited. Furthermore, microfabrication such as the partition walls described above has low mass productivity and is not practical. Therefore, an object of the present invention is to provide an electrochromic display panel that can easily suppress the expansion of the pixel coloring area without impairing such reflectance and image quality.

Each aspect of the invention related to the present application is as follows.

First, on the substrate, a data line extending in the first direction, a scanning line extending in the second direction intersecting the data line, and a pixel arranged to correspond to the intersecting region of the data line and the scanning line An electrochromic display panel comprising an electrode and a thin film transistor as a part of a laminated structure, the shield electrode covering from the data line and the scanning line and having a width of 2 μm to 4 μm wider than the data line and the scanning line It is an electrochromic display panel provided with.

Furthermore, the electrochromic display panel is provided with an insulating film on the surface of the scanning line and the data line.

The width of the insulating film formed on the scanning line and the data line is an electrochromic display panel formed to be larger than the width of the shield electrode on the scanning line and the data line.

The shield electrode is an electrochromic display panel arranged on the thin film transistor so as to shield light.

The thickness of the shield electrode is an electrochromic display panel having a thickness of 150 nm to 400 nm.

Also, the electrochromic display panel is provided with an insulating film on the surface of the shield electrode.

Further, the electrochromic display panel is provided with a partition wall for partitioning adjacent pixels on the surface of the shield electrode.

Normally, in an adjacent pixel, when an electric current is passed through one of the pixel electrodes, an electric field spreads in the electrolyte layer, and the color change of the display layer on the opposite electrode is larger than the area of the electrode, and the display layer on the adjacent electrode is also discolored. Resulting in.

However, as in the present invention, the shield electrode is provided on the data line and the scanning line between the pixels, and is formed wide so that the spread of the electric field between the adjacent pixels is suppressed, and between the pixels. Therefore, a clear color change is possible.

Furthermore, in the electrochromic method, the present invention can suppress the spread of the electric field between adjacent pixels even in a panel with higher resolution (100 ppi or more), so that a high-quality image can be displayed on the panel with high resolution. Can do.

With such a configuration, an electrochromic display medium that easily improves the problems of expansion of pixel area and low image quality display in an electrochromic display medium can be manufactured.

FIG. 1 is an equivalent circuit of various elements and wirings in a plurality of pixels formed in a matrix that forms an image display region of an electrochromic display panel. FIG. 2 is a plan view of a plurality of adjacent pixels on a TFT substrate on which data lines, scanning lines, shield electrodes, and pixel electrodes are formed. FIG. 3 is a plan view in which elements for showing the relationship among the data lines, scanning lines, shield electrodes, and pixel electrodes in FIG. 2 are extracted. FIG. 4 is a cross-sectional view taken along the line A-A 'of FIG. 2, and is a cross-sectional view of an electrochromic display panel according to an embodiment in which the electrochromic material according to the present invention is used. FIG. 5 is a cross-sectional view taken along the line A-A ′ of FIG. 2, and is a cross-sectional view when a partition wall is formed on the shield electrode.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The electrochromic display panel of the present invention can be driven in an active matrix by being provided with data lines, scanning lines, pixel electrodes, and thin film transistors.

First, the configuration of the pixel portion of the electrochromic display panel according to the first embodiment of the present invention will be described with reference to FIGS. First, FIG. 1 is an equivalent circuit of various elements and wirings in a plurality of pixels formed in a matrix that constitutes an image display region of an electrochromic display panel. FIG. 2 is a plan view of a plurality of pixels adjacent to a TFT substrate on which data lines, scanning lines, shield electrodes, and pixel electrodes are formed. FIG. 3 is a plan view of data lines, scanning lines, shield electrodes, and pixels in FIG. It is the top view which extracted the element for showing the relationship of an electrode.

FIG. 4 is a cross-sectional view taken along the line A-A ′ of FIG. FIG. 5 is a cross-sectional view when a partition wall is formed on the shield electrode. In FIGS. 4 and 5, the scale of each layer and member is changed in order to make each layer thickness and member recognizable on the drawing.

In FIG. 1, each of a plurality of pixels formed in a matrix that forms an image display area in the present embodiment is formed with a pixel electrode 6 a and a TFT 20 for ON / OFF control of the pixel electrode 6 a. A data line 3 a to which an image signal is supplied is electrically connected to the drain of the TFT 20.

The image signal to be written to the data line 3a is supplied in the order of D1, D2,..., Dn.

Further, the scanning line 1a is electrically connected to the gate of the TFT 20, and the voltage is applied line-sequentially in the order of the scanning signals G1, G2,. The pixel electrode 6a is electrically connected to the source of the TFT 20, and by turning on the TFT 20 as a switching element for a certain period, the image signal supplied from the data line 3a is converted to D1, D2,. ..., Dn is written at a predetermined timing.

The image signals D1, D2,..., Dn written to the electrochromic display panel via the pixel electrode 6a are held between the counter electrodes formed over the entire display area of the counter substrate.

Here, in order to hold the image signal, a capacitor 30 is added in parallel with the electrochromic display element capacitor formed between the pixel electrode 6a and the counter electrode. The capacitor 30 includes an electrode 200 fixed at a constant potential.

Hereinafter, the actual configuration of the electrochromic display panel that realizes the above-described circuit operation by the scanning line 1a, the data line 3a, the TFT 20, and the like will be described with reference to FIGS.

2 and 3, a plurality of pixel electrodes 6a are provided in a matrix on the TFT array substrate 10, and the scanning lines 1a and data lines 3a are arranged along the vertical and horizontal directions of the plurality of pixel electrodes 6a. The shield electrode 12a is provided on each of the scanning line 1a and the data line 3a.

The scanning line 1a, the data line 3a, and the shield electrode 12a are made of a conductive film. The scanning line 1a includes a channel region 9a indicated by a hatched region, and the scanning line 1a functions as a gate electrode. Channel regions 9a are respectively provided in the vicinity of the intersection of the scanning line 1a and the data line 3a, and a pixel switching TFT 20 in which the main gate electrode of the scanning line 1a is disposed is provided. The shield electrode 12a has a thickness of 150 nm or more and 400 nm or less and is disposed on the TFT 20 so as to shield light.

2, the electrochromic display panel includes a substrate on which a TFT array made of a glass substrate is disposed, a TFT array substrate 10 and a transparent substrate disposed opposite to the substrate, as shown in FIG. And a counter substrate 18 made of

On the TFT array substrate 10 side, a pixel electrode 6a is provided as shown in FIG. 4, and a charge storage layer 14 is provided thereon. The pixel electrode 6a is made of, for example, an aluminum film, and the counter substrate 18 side is provided with a counter electrode 17 made of a transparent conductive film such as an ITO film over the entire display area, and below that. Is provided with a display layer 16. An electrolyte layer 15 is provided between the TFT array substrate 10 and the counter substrate 18 arranged so as to face each other, and an electrochromic display layer 19 is formed.

On the TFT array substrate 10, each component including the pixel electrode 6a is provided in a laminated structure. A first interlayer insulating film 11 is provided between the scanning line 1a and the data line 3a, and a second interlayer insulating film 12 is provided between the scanning line 1a and the data line 3a and the shield electrode 12a. By forming the width of the two-layer insulating film 12 larger than the width of the shield electrode 12a, the above-described elements are prevented from being short-circuited. Although not shown, an insulating film may be provided on the surface of the shield electrode 12a.

The electrochromic display layer 19 can apply a positive or negative voltage or a current to flow between the pixel electrode 6a and the counter electrode 17, and an electric field is generated in the electrochromic display layer 19 by changing the voltage of the data line 3a. As a result, the display layer 16 and the charge storage layer 14 are oxidized and reduced.

When the pixel electrode 6a is a positive electrode, the charge storage layer 14 loses electrons and is oxidized, and electrons are donated and reduced to the display layer 16 of the counter electrode 17 serving as a counter electrode. On the contrary, when the pixel electrode 6a is a negative electrode, electrons are donated to the charge storage layer 14 and reduced, and the display layer 16 loses electrons and is oxidized.

As the display layer is oxidized and reduced, the visible light absorption wavelength region appears or changes color as it moves.

When the display layer is colorless and transparent without absorbing visible light, coloration by the reflective material dispersed in the electrolyte layer 15 is observed.

Further, the effect of the present invention will be described with reference to FIG.

In a general adjacent pixel configuration, when a current is applied to one side to promote a color change in the display layer, in addition to the electric field applied in the vertical direction between the pixel electrode 6a and the counter electrode 17, a horizontal direction parallel to the substrate surface is obtained. Phenomenon such as the influence of the directional electric field, the range of color change in the display layer extends to the display area of the adjacent pixel, the color of the adjacent pixel changes, or a clear display boundary with the adjacent pixel does not appear May occur.

As shown in FIG. 4, in the configuration according to the present invention, the shield electrode 12a connected to the external terminal is arranged between the pixels so that the same potential as the counter electrode 17 or an arbitrary potential can be applied from the external drive circuit. When a current is passed through the pixel, the color change and the spread of the electric field in the display layer between the pixels are suppressed on the shield electrode without being influenced by the electric field of the adjacent pixel. As a result, only the display layer corresponding to the pixel electrode undergoes a color change, and the color change does not occur in the display area of the pixel electrode adjacent to the pixel electrode that promoted the color change, and a clear display area with the adjacent pixel Appears and a high-quality image is displayed.

The shield electrode 12a is preferably formed wider than the data line 3a and the scanning line 1a by 2 μm to 4 μm. When the scanning line 1a, the data line 3a, and the edge of the TFT 20 region to the edge of the shield electrode 12a are less than 2 μm, the film is reduced due to damage (etchant, etc.) during etching in the shield electrode 12a formation process, and the TFT due to light leakage There is a risk of deteriorating characteristics and the effect of suppressing electric field. Further, when the width from the edge of the scanning line 1a, the data line 3a, and the TFT 20 region to the edge of the shield electrode 12a is formed wider than 4 μm, the aperture ratio may be sacrificed in the application of a high resolution panel (100 ppi or more). There is.

As shown in FIG. 5, in the configuration of the present invention, by providing a thick partition 40 on the shield electrode 12a, adjacent pixels can be separated three-dimensionally and the electric field can be more effectively suppressed.

In the above embodiment, the active matrix electrochromic display panel includes a thin film transistor for each pixel. However, the present invention is not limited to this. For example, a passive matrix electrochromic display panel may be used.

Hereinafter, materials, members, and structures used in the present invention will be described.

The electrochromic display layer is formed of an electrochromic material, a supporting electrolyte, a reflective material, and a charge storage material.

General organic and inorganic compounds can be used for the electrochromic material. Specifically, low molecular organic electrochromic compounds such as viologens, phenothiazines, anthraquinones, styryl spiropyrans, pyrazolines, fluorans, styryl spiropyran dyes, phthalocyanines, polyaniline, polythiophene, polypyrrole, etc. Inorganic compounds such as molecular compounds, titanium oxide, molybdenum oxide, niobium oxide, iridium oxide, vanadium oxide, tungsten oxide, indium oxide, iridium oxide, nickel oxide, Prussian blue, and Prussian blue analogues in which the coordination metal is replaced by other than iron Based electrochromic compounds.

Furthermore, it has been found that leuco dyes, which are generally electricity-donating organic substances, can also be electrically colored and decolored.

For example, electron-donating dye precursors such as leucooramines, diarylphthalides, polyarylcarbinols, acylauramines, arylolamines, rhodamine B-lactams, indolines, spiropyrans, and fluorans Is mentioned.

For low-molecular materials, a porous layer made of a mineral such as titanium oxide may be formed on the electrode layer and adsorbed.

As a method for forming the display layer, the electrochromic material listed above is used directly or mixed with a binder to form a paint, and screen printing, micro gravure coater, kiss coater, comma coater, die coater, bar coater, spin coater, etc. A typical coating technique can be used.

Further, the projections matched to the pixel electrodes are formed by a coating method that can be patterned such as screen printing or ink jet printing.

Examples of the supporting salt include inorganic ion salts such as alkali metal salts and alkaline earth metal salts, quaternary ammonium salts, acids and alkalis. Further specific examples of the supporting salt include LiClO ₄ , LiBF ₄ , LiAsF ₆ , LiPF ₆ , LiCF ₃ SO ₃ , CF ₃ COOLi, KCl, NaClO ₃ , NaCl, NaBF ₄ , NaSCN, KBF ₄ , Mg ( ClO ₄ ) ₂ , Mg (BF ₄ ) _{2 and the} like.

As the reflective material dispersed in the electrolyte layer, examples of the white material include magnesium oxide, barium sulfate, and titanium oxide. Examples of the black material include carbon black made of carbon such as lamp black and bone black, and titanium black powder made of an inorganic material. Furthermore, if it is blue, cobalt aluminate, cobalt chrome blue, phthalocyanines, and if it is red, anthraquinone and azo compounds may be mentioned. In order to disperse the reflective material in the electrolyte layer, the viscosity of the electrolyte layer may be increased by dissolving a polymer material such as an acrylic resin or a urethane resin in the electrolyte layer. Alternatively, a dispersant or a surfactant may be added.

The same material as the electrochromic material can be used as the charge storage material. However, a stable material that is unlikely to react with other compounds in both oxidized and reduced forms such as Prussian blue and ferrocene is preferable.

The counter substrate has a structure in which a transparent electrode is formed on a transparent base material. As the transparent substrate, polyethylene terephthalate (PET), polycarbonate, polyimide, polyethylene naphthalate, polyethersulfone, acrylic resin, polyvinyl chloride or other plastic film, glass, or the like can be used. What can be used as the transparent electrode material is a conductive oxide having transparency such as indium oxide, tin oxide and zinc oxide such as ITO. Conventional techniques such as vapor deposition, sputtering, and CVD can be used to form the transparent electrode.

The TFT array substrate can be an active matrix type electrode plate in which thin transistors using amorphous silicon or polycrystalline silicon, which are used for driving general liquid crystal panels, are arranged. Alternatively, a back electrode plate capable of large-scale active matrix driving may be used by arranging a large number of electrodes in a grid pattern on the front surface of the printed circuit board and laying wiring on the back surface through through holes for each electrode.

The shield electrode wiring can be formed using a known material and a forming method, and the material and the forming method are not limited. Examples of the shield electrode material include tantalum (Ta), aluminum (Al), Copper (Cu) etc. are mentioned.

Further, since the shield electrode is formed on the thin film transistor, it is possible to suppress the light from entering the TFT, and to reduce the change in characteristics of the TFT due to the light.

The barrier rib can be formed using a known material and a forming method, and the material and the forming method are not limited. Examples of the barrier rib material include a thick film photoresist. The height of the partition wall is preferably 50% or more with respect to the total thickness of the electrochromic display layer.

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. However, the present invention is not limited by the following description.

[Example 1]
<Preparation of front electrode substrate>
A dispersion obtained by dispersing 1.0 mol / l of a water-soluble Prussian blue dispersion as an electrochromic material on a transparent electrode substrate formed using indium tin oxide as an electrode on 100 mm square glass was applied with a spin coater. A front electrode substrate having a coating film of about 0.5 μm was obtained by drying at 5 ° C. for 5 minutes.

Subsequently, a coating solution prepared by mixing 0.5 mol / l Prussian blue and polyethylene glycol in pure water was prepared, and a 250 μm square pattern was printed on the front substrate by ink jet printing. A stepped front electrode substrate with a step of 4 μm was obtained.

<Preparation of back electrode substrate>
As the element formation on the glass which is the back electrode plate, a film forming process by sputtering, vapor deposition or CVD, a mask process such as photolithography, and a thin film shape processing process such as etching are appropriately performed. The electrodes are formed by patterning, a first interlayer insulating film is formed, a switching element (TFT) is formed by patterning for each pixel, and then the second electrode is formed by patterning. At this time, a contact hole is formed in advance so as to connect the first electrode and the second electrode.

The TFT (hydrogenated amorphous silicon (a-Si: H)) here is generally formed by a plasma CVD method or a reactive sputtering method. For example, when n-type hydrogenated amorphous silicon is formed by plasma CVD, monosilane (SiH ₄ ) or higher silane and phosphine (PH ₃ ) are used as source gases, and these are decomposed by RF discharge to a temperature of 200 ° C. It is deposited on the substrate held at 300 ° C. or lower.

The hydrogenated amorphous silicon formed by such a method contains about 10 atm% to 20 atm% of hydrogen, and this hydrogen has an important influence on the characterization of the hydrogenated amorphous silicon. Hydrogen contained in this hydrogenated amorphous silicon has a direct role of removing dangling bonds. In addition, it has a role in the surface process when forming a film of hydrogenated amorphous silicon and a role as a structural relaxation agent for the network, and the effects of these roles are coupled indirectly with the thermal effect due to the temperature of the substrate. It also reduces dangling bonds.

In other words, Si—H bonds in hydrogenated amorphous silicon reduce unstable dangling bonds and realize structural agility, and crystalline Si and P are formed by P (phosphorus, V group) and B (boron, III group). A pn junction by similar substitutional doping is realized. Such a property of hydrogen in hydrogenated amorphous silicon is an important property in application that enables application of hydrogenated amorphous silicon to diodes and transistors.

Subsequently, after forming the second electrode, a second interlayer insulation is formed on the TFT by performing a film forming process such as sputtering, vapor deposition or CVD, a mask process such as photolithography, and a thin film shape processing process such as etching. A film is formed by patterning, and a shield electrode is formed by patterning 2 μm wider than the data line and the scanning line on the electrode to be the data line and the scanning line.

Here, the back electrode plate is a TFT substrate having a resolution of 102 ppi (pixel size 250 μm □) and an interelectrode distance of 15 μm in order to evaluate the applicability of a high-resolution panel. The prepared Prussian blue dispersion was applied by a spin coater in the same manner as the front electrode substrate to obtain a back electrode substrate using Prussian blue as a charge retention layer.

Furthermore, 0.1 M potassium hexafluorophosphate, PMMA (Wako Pure Chemicals) and titanium oxide (R-830, manufactured by Ishihara Sangyo) were dispersed as electrolytes in propylene carbonate to prepare an electrolyte solution.

<Production of evaluation substrate>
An ultraviolet curable resin (TB3026E, manufactured by ThreeBond) mixed with beads having a diameter of about 100 μm was applied to the end portion of the back electrode substrate with a dispenser to form a dam. Subsequently, the dam was filled with the prepared electrolytic solution, and the dam was bonded so that the stepped portion of the stepped front electrode substrate was aligned with the interpixel portion, and was irradiated with light of 500 mJ / cm ² (420 nm) and bonded.

<Evaluation of fabrication substrate>
(Drive evaluation)
An LSI was mounted on the completed substrate, and 1.5 V was applied to one pixel of the back electrode for 2 seconds to check whether the color changed from blue to transparent. The case where the color changed without any problem was evaluated as “++”, and the case where only a part of the color changed or the color did not change was evaluated as “−”.
(Electrode film state evaluation)
The edge of the shield electrode was observed with a microscope from the edge of the scanning line, data line, and TFT region. Regarding the formation state of the electrode film, the case where defects such as damage and film reduction were not observed was evaluated as “++”, and the case where defects such as damage and film reduction were observed was evaluated as “−”.
(Application evaluation to panels)
About the panel which has each line width, application to the panel with high resolution was evaluated from the aperture ratio of the produced panel. Here, as an evaluation, “++” indicates that the panel can be applied to the panel without any practical problem from the aperture ratio of each panel, and “+” indicates that there is no practical problem but the aperture ratio is sacrificed. The case where the aperture ratio was sacrificed was evaluated as “−”.
(Comprehensive evaluation)
Based on the result of each evaluation item, comprehensive evaluation was performed. Evaluation criteria are shown below. Evaluation criteria were “++” as “good”, “−” as “impossible”, and “++” as acceptable.

[Example 2]
Example 2 was the same as Example 1 except that the shield electrode was formed by patterning on the electrodes to be the data line and the scanning line so as to be 2.5 μm wider than the data line and the scanning line.

[Example 3]
Example 1 was the same as Example 1 except that a shield electrode was formed by patterning 3 μm wider than the data line and the scanning line on the electrode to be the data line and the scanning line.

[Example 4]
Example 1 was the same as Example 1 except that a shield electrode was formed by patterning on the electrodes to be the data line and the scanning line so as to be 3.5 μm wider than the data line and the scanning line.

[Example 5]
Example 1 was the same as Example 1 except that a shield electrode was formed by patterning 4 μm wider than the data line and the scan line on the data line and the scan line.

[Comparative Example 1]
Example 1 was the same as Example 1 except that the shield electrode was formed by patterning 1 μm wider than the data line and the scanning line on the data line and scanning line.

[Comparative Example 2]
Example 1 was the same as Example 1 except that a shield electrode was formed by patterning 5 μm wider than the data line and the scanning line on the data line and the scanning line.

[Comparative Example 3]
Example 1 was the same as Example 1 except that the shield electrode was formed by patterning 6 μm wider than the data line and the scanning line on the electrode to be the data line and the scanning line.

Table 1 shows the evaluation results of Examples 1 to 5 and Comparative Examples 1 to 3.

When an LSI was mounted on the substrates produced in Examples 1 to 5 and Comparative Examples 1 to 3, 1.5 V was applied to one pixel of the back electrode for 2 seconds to promote a color change from blue to transparent. Changed to a transparent part of about 250 μm square with the step as an edge, and was observed as a white pixel by the titanium oxide of the electrolytic solution. Further, when the adjacent two pixels were promoted to change in color from blue to transparent, the level difference between the pixels also changed to transparent and was observed as a continuous white pixel. In Comparative Example 1, a portion where the color did not change was observed.

Further, as a result of microscopic observation of the electrode film, no defects such as damage and film loss were observed in the electrode films of Examples 1 to 5 and Comparative Examples 2 and 3, but in Comparative Example 1 during the etching in the shield electrode forming process Film loss due to damage (such as an etchant) was observed. This film reduction is undesirable in terms of quality because it deteriorates TFT characteristics due to light leakage and impairs the electric field suppression effect.

Next, when an application evaluation to a panel was performed, in Examples 1 to 5, it was possible to form a panel without sacrificing the aperture ratio. In Comparative Example 1, film damage was observed, so application evaluation to the panel was not performed (evaluation is impossible). In Comparative Examples 2 and 3, since the shield electrode is formed to be wider than allowable for application to the panel, it has been necessary to produce it at the expense of the aperture ratio in order to be applied to this panel.

Based on the above results, as a comprehensive evaluation, a shield electrode formed on a data line and a scanning line, and a patterning pattern that is wider than 2 μm and 4 μm from the data line and the scanning line, is evaluated as “++ (good)”. The patterning pattern wider than 4 μm is judged to require sacrificing the aperture ratio, and is evaluated as “-(impossible)”. The patterning pattern narrower than 2 μm is confirmed to be damaged by the electrode film. Evaluated as “-(impossible)”. It was confirmed that good characteristics were obtained at a resolution of 102 ppi by patterning the shield electrode wider than the data line and the scanning line over 2 μm to 4 μm.

In Examples 6 to 10, the panel having a resolution of 150.3 ppi (pixel size: 169 μm □) was evaluated as a panel having a higher resolution than those of Examples 1 to 5.
[Example 6]
<Preparation of front electrode substrate>
A stepped front electrode substrate was prepared in the same manner as in Example 1 except that a coating solution in which 0.5 mol / l Prussian blue and polyethylene glycol were mixed in pure water was prepared and a pattern of 169 μm □ was printed by inkjet printing. .
<Preparation of back electrode substrate>
A shield electrode is formed on the data line and scan line electrode by patterning 2 μm wider than the data line and scan line, and the back electrode plate is a TFT substrate having a resolution of 150.3 ppi (pixel size 169 μm) and a distance between pixels of 15 μm. A back electrode substrate was produced in the same manner as in Example 1 except that it was used.
<Production of evaluation substrate>
It was produced in the same manner as in Example 1.

<Evaluation of fabrication substrate>
The same evaluation was performed using the same evaluation items as in Example 1.

[Example 7]
Example 6 was the same as Example 6 except that the shield electrode was formed by patterning on the electrodes to be the data line and the scanning line so as to be 2.5 μm wider than the data line and the scanning line.

[Example 8]
Example 6 was the same as Example 6 except that the shield electrode was formed by patterning 3 μm wider than the data line and the scanning line on the electrode to be the data line and the scanning line.

[Example 9]
Example 6 was the same as Example 6 except that the shield electrode was formed by patterning on the electrodes to be the data line and the scanning line so as to be 3.5 μm wider than the data line and the scanning line.

[Example 10]
Example 6 was the same as Example 6 except that the shield electrode was formed by patterning 4 μm wider than the data line and the scanning line on the data line and the scanning line.

[Comparative Example 4]
Example 6 was the same as Example 6 except that the shield electrode was formed by patterning 1 μm wider than the data line and the scanning line on the electrode serving as the data line and the scanning line.

[Comparative Example 5]
Example 6 was the same as Example 6 except that a shield electrode was formed by patterning 5 μm wider than the data line and the scan line on the data line and the scan line.

[Comparative Example 6]
Example 6 was the same as Example 6 except that the shield electrode was formed by patterning 6 μm wider than the data line and the scanning line on the electrode serving as the data line and the scanning line.

Table 2 shows the evaluation results of Examples 6 to 10 and Comparative Examples 4 to 6.

When an LSI was mounted on the substrates produced in Examples 6 to 10 and Comparative Examples 4 to 6, and 1.5 V was applied to one pixel of the back electrode for 2 seconds to promote a color change from blue to transparent. Changed to a transparent part of about 250 μm square with the step as an edge, and was observed as a white pixel by the titanium oxide of the electrolytic solution. Further, when the adjacent two pixels were promoted to change in color from blue to transparent, the level difference between the pixels also changed to transparent and was observed as a continuous white pixel. In Comparative Example 4, a portion where the color did not change was observed.

Further, as a result of microscopic observation of the electrode film, no defects such as damage and film loss were observed in the electrode films of Examples 6 to 10 and Comparative Examples 5 and 6, but in Comparative Example 4, the shield electrode was formed during the etching process. Film loss due to damage (such as an etchant) was observed. This film reduction is undesirable in terms of quality because it deteriorates TFT characteristics due to light leakage and impairs the electric field suppression effect.

Next, when the application evaluation to the panel was performed, in Examples 6 to 10, it was possible to form a panel without sacrificing the aperture ratio. In Comparative Example 4, film damage was observed, so application evaluation to the panel was not performed (evaluation not possible). In Comparative Examples 5 and 6, since the shield electrode is formed to be wider than the panel application allowance, in order to apply to this panel, it was necessary to make it at the sacrifice of the aperture ratio.

Based on the above results, as a comprehensive evaluation, a shield electrode formed on a data line and a scanning line, and a patterning pattern that is wider than 2 μm and 4 μm from the data line and the scanning line, is evaluated as “++ (good)”. The patterning pattern wider than 4 μm is judged to require sacrificing the aperture ratio, and is evaluated as “-(impossible)”. The patterning pattern narrower than 2 μm is confirmed to be damaged by the electrode film. Evaluated as “-(impossible)”. It was confirmed that good characteristics were obtained at a resolution of 150.3 ppi by patterning the shield electrode wider than the data line and the scanning line over 2 μm to 4 μm.

The same applies to the case where the shield electrode is formed by the same method as in Example 6 and then patterned using a thick film photoresist by a photolithography method or the like and baked to form a partition wall. As a result of the evaluation, it was confirmed that the same result as this time was obtained.

From the above results, in electrochromic panels, it was confirmed that there was no abnormality in drive evaluation, electrode film state evaluation, and application evaluation in a high resolution panel (100 ppi or more), and the influence of the electric field on adjacent pixels also in display performance It was confirmed that good display characteristics were obtained with a high-resolution panel.

As described above, according to the present invention, for example, the following effects can be obtained. In other words, the shield electrode is provided on the data line and the scanning line between the pixels, and is formed wide so that the spread of the electric field between the adjacent pixels is suppressed, and the color change between the pixels is small and clear. Color change is possible.

The present invention is useful for display devices such as electronic paper.

1a scanning line

3a data line

6a pixel electrode

9a channel region 10 TFT array substrate 11 first interlayer insulating film 12 second interlayer insulating film 12a shield electrode 14 charge accumulation layer 15 electrolyte layer 16 display layer 17 counter electrode 18 counter substrate 19 electrochromic Display layer 20 TFT
30 Capacity 40 Bulkhead 200 Electrode

Claims

On the substrate, the data lines extending in the first direction, the scanning lines extending in the second direction intersecting the data lines, and the intersecting regions of the data lines and the scanning lines are arranged. In an electrochromic display panel provided with a pixel electrode and a thin film transistor as part of a laminated structure,
An electrochromic display panel comprising a shield electrode that covers the data line and the scanning line and is formed wider than the data line and the scanning line by 2 μm to 4 μm.
The electrochromic display panel according to claim 1, wherein an insulating film is provided on a surface of the scanning line and the data line.
3. The electrochromic display panel according to claim 2, wherein a width of the insulating film formed on the scanning line and the data line is formed larger than a width of a shield electrode on the scanning line and the data line.
4. The electrochromic display panel according to claim 1, wherein the shield electrode is disposed on the thin film transistor so as to shield light.
The electrochromic display panel according to any one of claims 1 to 4, wherein a thickness of the shield electrode is 150 nm or more and 400 nm or less.
The electrochromic display panel according to claim 1, wherein an insulating film is provided on the surface of the shield electrode.
The electrochromic display panel according to any one of claims 1 to 5, further comprising a partition wall for partitioning adjacent pixels on the surface of the shield electrode.