JP2007279356A - Image display medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display medium wherein the occurrence of cracks of thin film electrodes is suppressed in a thermocompression bonding process in manufacturing, or in deformation like bending or twisting in use. <P>SOLUTION: An image display medium 100 comprises: a display layer 101 comprising liquid crystal etc.; first and second transparent substrates 104 and 105 which are disposed in opposition to each other with the display layer 101 between them and have first and second transparent thin film electrodes 102 and 103; first and second taking-out electrodes 106 and 107 for electric connection to the first and second thin film electrodes 102 and 103 and to the outside; second intermediate electrodes 109 and 110 which electrically connect the first and second thin film electrodes 102 and 103 and the first and second taking-out electrodes 106 and 107 and are made of a material having lower rigidity and hardness than those of the first and second taking-out electrodes 106 and 107; and a thermoplastic film 200 formed so as to cover an entire configuration part. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a flexible image display medium whose entire surface is covered with a thermoplastic film.

  In recent years, image display media called electronic paper or digital paper having the advantages of both electronic display and paper have attracted attention as image display media, in addition to paper media and electronic display devices.

  In addition, development of an IC card to which a display function is added using such electronic paper has been performed, and there is a technique of forming a thermoplastic film on the surface by thermocompression bonding in order to protect the IC card from external damage.

  10A and 10B are cross-sectional views of an image display medium (IC card with electronic paper) having a conventional thermoplastic film.

  An image display medium 100 includes a display layer 101 made of liquid crystal or the like, and transparent first and second substrates 104 having transparent first and second thin-film electrodes 102 and 103 arranged to face each other with the display layer 101 interposed therebetween. 105 and first and second extraction electrodes 106 and 107 for electrical connection with the outside formed on the surfaces of the first and second thin film electrodes 102 and 103 (the second extraction electrode is not shown) And a thermoplastic film 200 having an extraction hole 108 formed on the surface so as to cover the entire component part and for connecting to the first and second extraction electrodes 106 and 107 from the outside. Outlined.

  However, when deformation such as bending or twisting is applied to the image display medium 100, for example, as shown in FIG. 10B, the portion of the surface of the first thin film electrode 102 where the edge of the first extraction electrode 106 contacts There is a risk of stress concentration and cracking and disconnection. Depending on the bending direction, cracks are also generated on the surface of the second thin film electrode 103 for the same reason.

  The occurrence of these cracks is caused by the first and second thin film electrodes made of indium tin oxide (ITO) or the like because the first and second extraction electrodes 106 and 107 made of metal such as Ni have high rigidity and hardness. 102 and 103 occur without being able to withstand the stress. A crack is generated in the first and second thin film electrodes 102 and 103, thereby causing a display defect of the image display medium 100.

On the other hand, some conventional image display media use an anisotropic conductive resin as a lead electrode to suppress disconnection or contact failure of the lead electrode due to repeated bending and attachment / detachment with an external device (for example, Patent Documents). 1).
JP 2004-177475 A

  However, according to this image display medium, the problem that the thin film electrode is cracked by receiving stress from the extraction electrode has not been solved.

  Accordingly, an object of the present invention is to provide an image display medium that suppresses the occurrence of cracks in a thin film electrode when deformation such as bending or twisting is applied.

  In one aspect of the present invention, in order to achieve the above object, in an image display medium whose entire surface is covered with a thermoplastic film, the display layer and the first and second layers disposed opposite to each other with the display layer interposed therebetween First and second substrates having thin film electrodes, and first and second extraction electrodes having higher rigidity than the first and second thin film electrodes and electrically connected to the outside; First and second intermediate electrodes having lower rigidity than the first and second extraction electrodes, and electrically connecting the first and second thin film electrodes and the first and second extraction electrodes And an image display medium characterized by comprising:

  According to one aspect of the present invention, the first and second extraction electrodes and the first and second thin film electrodes are not directly joined but connected via the first and second intermediate electrodes. The first and second intermediate electrodes are lower in rigidity or hardness than the first and second extraction electrodes, so that when the image display medium is subjected to deformation such as bending or twisting, The first and second intermediate electrodes disperse stress during deformation, and the occurrence of cracks in the first and second thin film electrodes is suppressed. As a result, the image display quality can be maintained even when the image display medium is subjected to deformation such as bending or twisting. The rigidity is, for example, bending rigidity or torsional rigidity.

  In addition, the first and second extraction electrodes and the first and second thin film electrodes are not directly joined but connected via the first and second intermediate electrodes. Since the second intermediate electrode is lower in hardness than the first and second extraction electrodes or superior in cushioning properties, the second intermediate electrode is used when the thermoplastic film is thermocompression bonded to the image display medium by a bonding tool in the manufacturing process. The occurrence of cracks in the first and second thin film electrodes can be suppressed. Thereby, the yield can be improved.

  The first and second intermediate electrodes may have higher rigidity than the first and second thin film electrodes. Further, it may have a lower hardness than the first and second extraction electrodes. Further, it may be thicker than the first and second thin film electrodes and thinner than the first and second extraction electrodes.

  The first and second intermediate electrodes may be composed of a sheet electrode, a plurality of strip electrodes, and a plurality of linear electrodes. Moreover, you may have a mesh structure and a nonwoven fabric structure.

  One of the first and second intermediate electrodes has a conductive film formed on both side surfaces of the support substrate, has at least one through hole, and the conductive film on both side surfaces of the support substrate has the through hole. The other may have a configuration in which a conductive film is formed on at least one surface of the support substrate.

  The image display medium is, for example, an IC card having a display function using electronic paper such as an optical writing type, a toner display type, and an electrophoretic method, and the display layer is a liquid crystal depending on the type of the image display medium. And a layer having colored particles and the like.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the image display medium which suppresses generation | occurrence | production of the crack in a thin film electrode at the time of adding deformation, such as a bending and a twist.

[First Embodiment]
(Configuration of image display medium)
FIGS. 1A and 1B are a top view and a bottom view of an image display medium according to the first embodiment of the present invention, and FIGS. 2A and 2B are partial cross-sectional views. . 2 (a) and 2 (b) are diagrams in which cut surfaces along chain lines AA ′ and BB ′ in FIG. 1 are viewed in the directions of arrows in the drawing.

  The image display medium 100 includes a transparent first and second thin film electrodes 102 and 103 that are disposed opposite to each other with a display layer 101 made of liquid crystal or the like interposed therebetween. Substrates 104 and 105, first and second thin film electrodes 102 and 103, first and second extraction electrodes 106 and 107 for electrical connection to the outside, and first and second thin film electrodes 102, 103 and first and second extraction electrodes 106, 107 are electrically connected to each other, and first and second intermediate electrodes 109, 110, and a thermoplastic film 200 formed so as to cover the entire components; It is comprised roughly.

  In the present embodiment, the image display medium 100 will be described as optical writing type electronic paper. In the case of optical writing type electronic paper, the display layer 101 is not shown, but a liquid crystal layer whose reflectance (transmittance) changes according to an applied voltage, a light absorption layer that absorbs light, and a resistance caused by light irradiation. It has a configuration in which photoconductive layers with decreasing values are stacked in order from the display surface side, or a configuration in which a light absorption layer, a photoconductive layer, an isolation layer, and a liquid crystal layer are stacked in order from the display surface side. The liquid crystal layer includes, for example, a microcapsule in which cholesteric liquid crystal is sealed. The photoconductive layer includes a charge transport layer and a pair of charge generation layers stacked on both sides of the charge transport layer. Thus, an alternating voltage can be applied to the liquid crystal layer, so that deterioration of the liquid crystal layer can be suppressed, and the driving voltage can be lowered and the lifetime of the electronic paper can be increased.

  At least one of the first and second substrates 104 and 105 located on the display side is made of a transparent resin material such as polyethylene terephthalate (PET) having a thickness of 100 μm, for example.

  At least one of the first and second thin film electrodes 102 and 103 is a transparent electrode made of, for example, 50 nm indium tin oxide (ITO) or zinc oxide.

  Both the first and second thin film electrodes 102 and 103 have the form of full-surface electrodes. Depending on the type of the image display medium, for example, one is a full-surface electrode and the other is a pixel electrode, one is a scan electrode and the other is a signal electrode, and one is a signal electrode and the other moves on the signal electrode. It may have the form of a scanning line electrode. In addition, when the first and second thin film electrodes 102 and 103 are composed of a plurality of electrodes such as row electrodes and column electrodes, when there are a plurality of extraction electrodes, the first and second extraction electrodes 106 and 107 are used. Are composed of electrode groups corresponding to the first and second thin film electrodes 102 and 103, respectively.

  The first and second extraction electrodes 106 and 107 are made of a metal such as Ni having a thickness of 140 μm, for example, and have higher rigidity or hardness than the first and second thin film electrodes 102 and 103.

  The first and second intermediate electrodes 109 and 110 are, for example, first and second extractions such as a conductive mesh, a conductive paste-impregnated mesh, a conductive nonwoven fabric, a conductive rubber, a conductive adhesive sheet, a conductive adhesive, and a metal stay. The first and second thin film electrodes 102 and 103 are connected to the first and second extraction electrodes 106 and 107 and are electrically connected to each other.

  The first and second intermediate electrodes 109 and 110 are connected to the first and second thin film electrodes 102 and 103 and the first and second extraction electrodes 106 and 107 by, for example, adhesion using a conductive paste such as an Ag paste. It is performed by pressure bonding by heating.

  The conductive mesh is, for example, a braided material in which a base material having a mesh structure made of PET having a thickness of 50 to 200 μm is coated with a metal such as Al, a metal such as Cu, or a metal such as tin plated thereon. Can be used. Due to its mesh structure, the conductive mesh disperses stress during deformation and has excellent cushioning properties.

  The conductive paste-impregnated mesh is obtained by, for example, impregnating a mesh material having a thickness of 50 to 200 μm with a conductive paste such as an Ag paste, and the mesh material may be conductive or non-conductive. Due to its mesh structure, the conductive paste-impregnated mesh disperses stress during deformation and has excellent cushioning properties.

  As the conductive nonwoven fabric, for example, a material having a thickness of 50 to 200 μm in which a fiber base material made of PET or the like is impregnated with a metal such as Cu or Ag can be used. The conductive nonwoven fabric disperses the stress at the time of deformation from the nonwoven fabric structure, and is excellent in cushioning properties.

  As the conductive rubber, for example, a rubber material having a thickness of 1 to 200 μm in which conductive particles such as Cu are dispersed can be used.

  For the conductive adhesive sheet, for example, a resin material having a thickness of 1 to 200 μm in which conductive particles such as Cu and Ag are dispersed can be used.

  As the conductive adhesive, for example, a resin paste in which conductive particles such as Cu and Ag are dispersed and hardened to have a thickness of 1 to 200 μm can be used.

  As the metal stay, for example, a metal stay made of Cu or the like and having a thickness of 1 to 200 μm can be used.

  The thermoplastic film 200 is made of, for example, a transparent thermoplastic resin using PET, amorphous PET (PET-G), polyvinyl chloride, polyester, or a combination thereof.

  The thermoplastic film 200 is formed by thermocompression bonding first, second, and third thermoplastic members 201, 202, and 203, which will be described later, to the surface of the image display medium 100 using a bonding tool, as shown in FIG. As shown in FIG. 2, the first and second extraction electrodes 106 and 107 are connected to the first and second extraction electrodes 106 and 107 from the outside. The take-out hole 108 may be formed on the opposite surface shown in FIG. Further, the extraction hole 108 may be provided after the thermoplastic film 200 is formed on the surface of the image display medium 100.

  As shown in FIGS. 1A and 1B, an IC chip 111 such as a wireless tag can be mounted as necessary.

  FIG. 3 is an exploded perspective view of the image display medium. The thermoplastic film 200 is represented as first, second, and third thermoplastic members 201, 202, and 203 before thermocompression bonding. The first and second thermoplastic members 201 and 202 have a plate shape that covers the surface of the image display medium 100, and the third thermoplastic member 203 has a frame shape that covers the side surface. The shapes of the first, second and third thermoplastic members 201, 202 and 203 are not limited to those shown in the figure. In addition, a block-shaped thermoplastic member is used to form a gap. May be filled.

  The first and second thermoplastic members 201 and 202 are melted, for example, on the surface of a mother layer made of PET having a thickness of 100 μm, for example, a hot-melt adhesive having a thickness of 25 μm, a copolyester-based hot melt adhesive, or the like. Has a layer. The molten layer has a lower melting point than the mother layer, and thermocompression bonding is performed with the surface on which the molten layer is formed facing the image display medium 100 surface side.

(Production of image display medium)
4 (a) to 4 (c) are partial cross-sectional views illustrating each manufacturing process of the image display medium according to the first embodiment of the present invention. 4A to 4C are the same as the cross section shown in FIG.

  First, as shown in FIG. 4A, an image display medium 100 before forming the thermoplastic film 200 is prepared.

Next, as shown in FIG. 4B, the image display medium 100 is covered with the first, second, and third thermoplastic members 201, 202, and 203, and the entire image display medium 100 fixed on the table is covered. Using a bonding tool (not shown), heating (for example, 60 to 150 ° C.) and pressurization (for example, 0.1 to 1 N / mm ² ) are performed from above in a vertical direction with a cushioning material interposed therebetween.

  In addition, for example, the heating and pressurization may be performed under the same conditions from both the front and back surfaces of the image display medium 100 using a laminating method using a heating roller (not shown).

  Through the above steps, as shown in FIG. 4C, the first, second and third thermoplastic members 201, 202 and 203 become the thermoplastic film 200 and cover the surface of the image display medium 100.

  At this time, the first and second extraction electrodes 106 and 107 and the first and second thin film electrodes 102 and 103 are not directly joined but connected via the first and second intermediate electrodes 109 and 110. The first and second intermediate electrodes 109 and 110 are lower in hardness than the first and second extraction electrodes 106 and 107 or have excellent cushioning properties. Therefore, a thermoplastic film is applied to the image display medium 100 by a bonding tool. The occurrence of cracks in the first and second thin film electrodes 102 and 103 when thermocompression bonding 200 is suppressed.

  Through the above steps, as shown in FIG. 4C, the first, second and third thermoplastic members 201, 202 and 203 become the thermoplastic film 200 and cover the surface of the image display medium 100.

(Effects of the first embodiment)
According to the first embodiment, the first and second intermediate electrodes are not directly joined to the first and second extraction electrodes 106 and 107 and the first and second thin film electrodes 102 and 103. 109 and 110, and the first and second intermediate electrodes 109 and 110 are less rigid or harder than the first and second extraction electrodes 106 and 107, so that the image display medium 100 is bent. When deformation such as torsion is applied, the first and second intermediate electrodes 109 and 110 disperse the stress at the time of deformation, and the occurrence of cracks in the first and second thin film electrodes 102 and 103 is suppressed. As a result, the image display quality can be maintained even if the image display medium 100 is subjected to deformation such as bending or twisting.

  Further, the first and second extraction electrodes 106 and 107 and the first and second thin film electrodes 102 and 103 are not directly joined but connected via the first and second intermediate electrodes 109 and 110. The first and second intermediate electrodes 109 and 110 are lower in hardness than the first and second extraction electrodes 106 and 107 or have excellent cushioning properties. Therefore, in the manufacturing process, the first and second intermediate electrodes 109 and 110 are attached to the image display medium 100 by a bonding tool. Generation of cracks in the first and second thin film electrodes 102 and 103 when the thermoplastic film 200 is thermocompression bonded can be suppressed. Thereby, the yield can be improved.

[Second Embodiment]
The second embodiment differs from the first embodiment in the configuration of the first and second intermediate electrodes 109 and 110. Since other components are the same as those in the first embodiment, the description thereof is omitted.

(Configuration of image display medium)
FIGS. 5A and 5B are enlarged views showing a connection portion between the first and second intermediate electrodes, the first and second thin film electrodes, and the first and second extraction electrodes. 5A and 5B correspond to the directions of FIGS. 1A and 1B, respectively.

  The first and second intermediate electrodes 109 and 110 are composed of a plurality of strip-shaped electrodes. As for the material, the same material as in the first embodiment can be used. Also, the thickness of each material can be the same as in the first embodiment.

(Effect of the second embodiment)
According to the second embodiment, the same effect as that of the first embodiment can be obtained. However, since the first and second intermediate electrodes 109 and 110 are composed of a plurality of strip-shaped electrodes, bending, Resistance to deformation such as twisting is further improved.

[Third Embodiment]
The third embodiment is different from the first embodiment in the configuration of the first and second intermediate electrodes 109 and 110. Since other components are the same as those in the first embodiment, the description thereof is omitted.

(Configuration of image display medium)
FIGS. 6A and 6B are enlarged views showing a connection portion between the first and second intermediate electrodes, the first and second thin film electrodes, and the first and second extraction electrodes. The directions with respect to the paper surface of FIGS. 6A and 6B correspond to the directions of FIGS. 1A and 1B, respectively.

  The first and second intermediate electrodes 109 and 110 are composed of a plurality of linear electrodes. As the material, for example, a metal thin wire such as Cu having a diameter of 1 to 100 μm can be used. Note that the cross section of the fine metal wire may not be a perfect circle.

(Effect of the third embodiment)
According to the third embodiment, the same effect as that of the first embodiment can be obtained. However, since the first and second intermediate electrodes 109 and 110 are composed of a plurality of linear electrodes, bending is performed. Further, resistance to deformation such as torsion is further improved.

[Fourth Embodiment]
The fourth embodiment is different from the first embodiment in the configuration of the first and second intermediate electrodes 109 and 110. Since other components are the same as those in the first embodiment, the description thereof is omitted.

(Configuration of image display medium)
FIGS. 7A and 7B are enlarged views showing the connection portions of the first and second intermediate electrodes, the first and second thin film electrodes, and the first and second extraction electrodes. 7A and 7B correspond to the directions of FIGS. 1A and 1B, respectively.

  8A and 8B are partial cross-sectional views of the image display medium. The cross sections shown in FIGS. 8A and 8B correspond to the cross sections shown in FIGS. 2A and 2B of the image display medium 100 according to the first embodiment.

  FIG. 9 is an enlarged cross-sectional view of the first and second intermediate electrodes.

  The first intermediate electrode 109 includes a conductive film 109b formed on both surfaces of the support substrate 109a and has at least one through hole 109c. The conductive film 109b on both sides of the support substrate 109a is electrically connected via the conductive film on the side surface of the through hole 109c. The conductive film 109 b on one surface is bonded to the first thin film electrode 102, and the conductive film 109 b on the other surface is bonded to the first extraction electrode 106.

  The second intermediate electrode 110 is configured by forming a conductive film 109b on one surface of the support substrate 110a. Since the conductive film 109b is formed only on one surface, a through hole is not required. The second thin film electrode 103 and the second extraction electrode 107 are joined to the conductive film 109b formed on one surface of the support substrate 110a.

  The support substrates 109a and 110a are made of a resin material such as PET, for example.

  The conductive films 109b and 110b are formed by, for example, depositing a metal such as Al on the surfaces of the support substrates 109a and 110a, or applying a conductive paste such as Ag paste or Al paste. Note that the conductive film 109b on both sides of the support substrate 109a and the conductive film on the side surface of the through hole 109c may be made of different materials.

(Effect of the fourth embodiment)
According to the fourth embodiment, the same effects as in the first embodiment can be obtained.

  The present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the invention. For example, the shape, size, arrangement, and the like of the first and second intermediate electrodes 109 and 110 are not limited to those shown in the drawings in the above embodiments.

  In addition, the constituent elements of the above embodiments can be arbitrarily combined without departing from the spirit of the invention.

(A), (b) is the top view and bottom view of the image display medium which concern on the 1st Embodiment of this invention. (A), (b) is a fragmentary sectional view of the image display medium based on the 1st Embodiment of this invention. 1 is an exploded perspective view of an image display medium according to a first embodiment of the present invention. (A)-(c) is the fragmentary sectional view which showed each manufacturing process of the image display medium based on the 1st Embodiment of this invention. (A), (b) is the connection part of the 1st and 2nd intermediate electrode which concerns on the 2nd Embodiment of this invention, a 1st and 2nd thin film electrode, and a 1st and 2nd extraction electrode FIG. (A), (b) is the connection part of the 1st and 2nd intermediate electrode which concerns on the 3rd Embodiment of this invention, 1st and 2nd thin film electrode, and 1st and 2nd extraction electrode FIG. (A), (b) is the connection part of the 1st and 2nd intermediate electrode which concerns on the 4th Embodiment of this invention, 1st and 2nd thin film electrode, and 1st and 2nd extraction electrode FIG. (A), (b) is a fragmentary sectional view of the image display medium based on the 4th Embodiment of this invention. (A), (b) is an expanded sectional view of the 1st and 2nd intermediate electrode which concerns on the 4th Embodiment of this invention. It is a fragmentary sectional view of the conventional image display medium.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Image display medium 101 Display layer 102 1st thin film electrode 103 2nd thin film electrode 104 1st board | substrate 105 2nd board | substrate 106 1st extraction electrode 107 2nd extraction electrode 108 Extraction hole 109 1st intermediate electrode 109a support substrate 109b conductive film 109c through-hole 110 second intermediate electrode 110a support substrate 110b conductive film 111 IC chip 200 thermoplastic film 201 first thermoplastic member 202 second thermoplastic member 203 third thermoplastic member

Claims (10)

In an image display medium whose entire surface is covered with a thermoplastic film,
A display layer;
First and second substrates having first and second thin film electrodes disposed opposite to each other across the display layer;
First and second extraction electrodes having higher rigidity than the first and second thin film electrodes and electrically connecting to the outside;
First and second intermediate electrodes having lower rigidity than the first and second extraction electrodes, and electrically connecting the first and second thin film electrodes and the first and second extraction electrodes When,
An image display medium comprising:   The image display medium according to claim 1, wherein the first and second intermediate electrodes have higher rigidity than the first and second thin film electrodes.   The image display medium according to claim 1, wherein the first and second intermediate electrodes have a lower hardness than the first and second extraction electrodes.   The first and second intermediate electrodes are thicker than the first and second thin film electrodes and have a thickness smaller than that of the first and second extraction electrodes. Image display media.   The image display medium according to claim 1, wherein the first and second intermediate electrodes are formed of sheet-like electrodes.   The image display medium according to claim 1, wherein the first and second intermediate electrodes include a plurality of strip electrodes.   The image display medium according to claim 3, wherein the first and second intermediate electrodes have a mesh structure.   The image display medium according to claim 3, wherein the first and second intermediate electrodes have a nonwoven fabric structure.   The image display medium according to claim 1, wherein the first and second intermediate electrodes include a plurality of linear electrodes. One of the first and second intermediate electrodes has a conductive film formed on both side surfaces of the support substrate, has at least one through hole, and the conductive film on both side surfaces of the support substrate has the through hole. Having a configuration that is conducted by
The image display medium according to claim 1, wherein the other has a configuration in which a conductive film is formed on at least one surface of the support substrate.

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