Touch panel and touch panel type display device

The present invention is related to a touch panel comprising: a first base that includes a first resistance film; a second base that includes a second resistance film; a conductor that is electrically connected to at least one of the first resistance film and the second resistance film; and a spacer that is interposed in a first facing area where the first resistance film faces the second resistance film. The spacer is also interposed in a second facing area where at least one of the first resistance film and the second resistance film faces the conductor. The present invention may further include an insulating film interposed in the second facing area, instead of the spacer interposed in the second facing area. The component materials of the insulating film are the same as those of the spacers.

CROSS-REFERENCE TO THE RELATED APPLICATIONS

This application is a national stage of international application No. PCT/JP2008/061779 filed Jun. 28, 2008, and claims the benefit of priority under 35 USC 119 to Japanese Patent Application No. 2007-169901 filed Jun. 28, 2007 and Japanese Patent Application No. 2007-169902 filed Jun. 28, 2007, the entire contents of all of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a touch panel mounted on a display screen of a liquid crystal display and the like. More specifically, the present invention relates to a touch panel type display device having the touch panel mounted on a display device.

BACKGROUND ART

For example, As a touch panel type display device, for example, there is one having a touch panel mounted on a liquid crystal display device to detect input coordinates based on a resistance change caused by a pressing operation (for example, see Patent Document 1).

A touch panel used on a screen input type display device disclosed in Patent Document 1 has a structure in which a second substrate made of glass is arranged facing a first substrate made of a polyethylene terephthalate film. The first substrate includes a first resistance film made of ITO (Indium Tin Oxide) and a wire electrode electrically connected to the first resistance film on the surface facing the second substrate. The second substrate includes a second resistance film made of ITO and an inter-substrate connecting wire electrode electrically connected to the second resistance film on the surface facing the first substrate. The wire electrode of the first substrate and the inter-substrate connecting wire electrode of the second substrate are electrically connected through an electrically conductive adhesive member. The electrically conductive adhesive member is made of an adhesive material and electrically conductive particles embedded in the adhesive material. The electrically conductive particles are prepared by plating the surface of plastic particles with metal (e.g., gold, nickel).

DISCLOSURE OF INVENTION

Problem to be Solved by the Invention

In the screen input type display device, unwanted contact may occur between the first resistance film and the second wire electrode positioned in a region facing the first resistance film. To suppress the occurrence of such a trouble, the shape of the first resistance film needs to be devised, for example, by patterning the first resistance film, so as not to face the second wire electrode. Devising the shape of the first resistance film deteriorates manufacturing efficiency.

An object of the present invention is to provide a touch panel and a touch panel type display device that can suppress unwanted contact between a resistance film and a wire electrode, and have superior manufacturing efficiency.

SUMMARY OF THE INVENTION

The present invention is related to a touch panel comprising: a first base that includes a first resistance film; a second base that includes a second resistance film; a conductor that is electrically connected to at least one of the first resistance film and the second resistance film; and a spacer that is interposed in a first facing area where the first resistance film faces the second resistance film.

The spacer is also interposed in a second facing area where at least one of the first resistance film and the second resistance film faces the conductor.

The present invention may further include an insulating film interposed in the second facing area, instead of the spacer interposed in the second facing area. The component materials of the insulating film are the same as those of the spacers.

The present invention further relates to a touch panel type display device including a display panel and the touch panel described above.

Advantage of the Invention

An example of a touch panel according to the present invention includes the spacer interposed in at least a part of the facing area where at least one of the first resistance film and the second resistance film faces the conductor. Another example of a touch panel according to the present invention includes an insulating film interposed in at least a part of the facing area where at least one of the first resistance film and the second resistance film faces the conductor. The touch panels according to the present invention thus can suppress unwanted contact between the resistance films and the conductor, even when external force (such as pressing force to make inputs with the touch panels) is applied to the touch panels. Therefore, the touch panels according to the present invention can suppress the occurrence of electrical failures.

When the spacer is interposed in the second facing area, the spacers in the first facing area and the second facing area can be formed in a single process. Alternatively, when the insulating film and the spacer are made of the same component materials, the insulating film can be formed in the same process as the spacer. The touch panels according to the present invention thus can be manufactured more efficiently than counterparts to suppress unwanted contact between the resistance films and the conductor in the second facing area by devising the shapes of the resistance films through patterning.

EXPLANATIONS OF LETTERS OR NUMBERS

Y Touch panel type display device

12First resistance film

22Second resistance film

23,24Inter-substrate connecting wire electrode

BEST MODE(S) FOR CARRYING OUT THE INVENTION

Touch panels and touch panel type display devices according to embodiments of the present invention will now be described with reference to the accompanying drawings.

To begin with, a touch panel and a touch panel type display device according to a first embodiment of the present invention will be described with reference toFIGS. 1 to 9.

Referring toFIGS. 1 to 4, the touch panel X1includes a first base10, a second base20, and an electrically conductive adhesive member30.

The first base10has flexibility on the whole, and is substantially rectangular in a plan view. The shape of the first base10in a plan view is not limited to being substantially rectangular, and may be other shapes. The first base10includes an insulating substrate11and a first resistance film12.

The insulating substrate11is a member serving to support the first resistance film12, and has translucency in a direction (e.g., an AB direction) intersecting its principal surface and also has electrical insulation properties. Translucency as used herein means permeability to visible light. Examples of the component material of the insulating substrate11include glass and translucent plastic. In particular, glass is preferable for the component material of the insulating substrate11in view of heat resistance. When using glass as the component material of the insulating substrate11, the thickness of the insulating substrate11is preferably set to be equal to or more than 0.1 millimeter and equal to or less than 0.3 millimeter to ensure sufficient shape stability and flexibility.

The first resistance film12contributes to detecting electric potentials at a contact point between the second base20and a second resistance film22, which will be described later, and has translucency in a direction (e.g., an AB direction) intersecting its principal surface. The first resistance film12is made of an electrically conductive material having a predetermined electrical resistance, and provided to extend substantially the whole surface of the principal surface of the insulating substrate11located on the side indicated by the arrow B. The resistance of the first resistance film12is set to be equal to or more than 200 Ω/□ and equal to or less than 1500 Ω/□. The thickness of the first resistance film12according to the present embodiment is set to be equal to or less than 2.0×10−2micrometers to ensure high resistance. Examples of the component material of the first resistance film12include ITO (Indium Tin Oxide), ATO (antimony trioxide), tin oxide, zinc oxide, and other translucent electrically conductive members.

The second base20is substantially rectangular in a plan view, and arranged to face the first base10. The shape of the second base20in a plan view is not limited to being substantially rectangular, and may be other shapes. The second base20includes an insulating substrate21, the second resistance film22, inter-substrate connecting wire electrodes23,24, wire electrodes25,26, and dot spacers27. The second base20also has an externally conductive area20athat is an area connected to a FPC (Flexible Printed Circuit) not shown, or the like. In the externally conductive area20a, respective one ends of the inter-substrate connecting wire electrodes23,24and the wire electrodes25,26are located.

The insulating substrate21serves to support the second resistance film22, the inter-substrate connecting wire electrodes23,24, the wire electrodes25,26, and the plurality of dot spacers27, and has translucency in a direction (e.g., an AB directions) intersecting a principal surface of the insulating substrate21and also has electrical insulation properties. Examples of the component material of the insulating substrate21include glass and translucent plastic. In particular, glass is preferable for the component material of the insulating substrate21in view of heat resistance. When using glass as the component material of the insulating substrate21, the thickness of the insulating substrate21is preferably set to be more than 0.7 millimeter to ensure sufficient shape stability.

The second resistance film22contributes to detecting electric potentials at a contact point between the first base10and the first resistance film12, and has translucency in a direction (e.g., an AB direction) intersecting its principal surface. The second resistance film22is made of an electrically conductive material having a predetermined electrical resistance, and provided in an area on the principal surface of the insulating substrate21located on the side indicated by the arrow A except for the rim (in an area where the first resistance film12is provided in a plan view). Translucency and electrical resistance required for the second resistance film22are the same as those for the first resistance film12. The component material of the second resistance film22can be the same as that of the first resistance film12.

The inter-substrate connecting wire electrodes23,24serve to apply a voltage to the first resistance film12through the electrically conductive adhesive member30, which will be described later, and are provided on the periphery of the second resistance film22. The inter-substrate connecting wire electrode23has one end disposed in the externally conductive area20aand the other end disposed in an end area on the side indicated by the arrow C of an adhesion area (i.e., the area surrounded by the dashed-two dotted line inFIG. 1) effected by the electrically conductive adhesive member30, which will be described later, on the insulating substrate21. The inter-substrate connecting wire electrode24has one end disposed in the externally conductive area20aand the other end disposed in an end area on the side indicated by the arrow D of the adhesion area effected by the electrically conductive adhesive member30.

The respective resistances between both ends of the inter-substrate connecting wire electrodes23,24are preferably set to be equal to or less than 0.01 time of the resistance between both ends of the first resistance film12in view of detection accuracy of the touch panel X1. The inter-substrate connecting wire electrodes23,24are formed of, for example, a metal thin film (line width: equal to or more than 0.5 millimeter and equal to or less than 2 millimeters; thickness: equal to or more than 0.5 micrometer and equal to or less than 2 micrometers) in view of hardness and shape stability. Examples of the metal thin film include an aluminum film, an aluminum alloy film, a multi-layered film of chromium and aluminum films, and a multi-layered film of chromium and aluminum alloy films. When the first resistance film12is made of ITO, the metal thin film is preferably made of a multi-layered film of chromium and aluminum films (chromium is interposed between ITO and aluminum) or a multi-layered film of chromium and aluminum alloy films (chromium is interposed between ITO and aluminum alloy) in view of adhesiveness with ITO. Examples of a method for forming the metal thin film include sputtering, evaporation, and chemical vapor deposition (CVD).

Forming the inter-substrate connecting wire electrodes23,24of a metal thin film can make the heights of the uneven surfaces by the inter-substrate connecting wire electrodes23,24and the wire electrodes25,26sufficiently smaller than the heights of the dot spacers27. This arrangement can sufficiently suppress the occurrence of unwanted contact between the inter-substrate connecting wire electrodes23,24or the wire electrodes25,26and the first resistance film12caused by small differences between the heights of the uneven surfaces by the inter-substrate connecting wire electrodes23,24or the wire electrodes25,26and the heights of the dot spacers27.

Making the metal thin film of an aluminum film, an aluminum alloy film, a multi-layered film of chromium and aluminum films, or a multi-layered film of chromium and aluminum alloy films can make wire resistance relatively low, as well as facilitating the forming of the thin film and the processing (e.g., patterning) of the thin film.

The wire electrodes25,26serve to apply a voltage to the second resistance film22. The wire electrode25has one end disposed in the externally conductive area20aand the other end disposed in an end of the second resistance film22on the side indicated by the arrow E. The wire electrode26has one end disposed in the externally conductive area20aand the other end disposed in an end of the second resistance film22on the side indicated by the arrow F.

The respective resistances between both ends of the wire electrodes25,26are preferably set to be equal to or less than 0.01 time of the resistance between both ends of the second resistance film22in view of detection accuracy of the touch panel X1. Like the inter-substrate connecting wire electrodes23,24, the wire electrodes25,26are formed of a metal thin film (line width: equal to or more than 0.5 millimeter and equal to or less than 2 millimeters; thickness: equal to or more than 0.5 micrometer and equal to or less than 2 micrometers). The metal thin film can be the same as the metal film to form the inter-substrate connecting wire electrodes23,24.

The dot spacers27serve to suppress unwanted contact between the first resistance film12and the second resistance film22in an area except for a predetermined position when the first resistance film12and the second resistance film22come into contact with each other at the predetermined position (when information input is performed). The dot spacers27are disposed in a matrix arrayed at substantially regular intervals in the CD directions and the EF directions on the insulating substrate21. More specifically, the dot spacers27are arrayed on the second resistance film22, predetermined areas of the inter-substrate connecting wire electrodes23,24except for their respective one ends (the area located in the externally conductive area20aof the second base20) and their respective other ends (the adhesion area effected by the electrically conductive adhesive member30), and predetermined areas of the wire electrodes25,26except for their respective one ends (the area located in the externally conductive area20aof the second base20).

The dot spacers27are preferably difficult to view as well as functioning as a prevention against unwanted contact between the first resistance film12and the second resistance film22, and are each formed in a hemisphere with a diameter of equal to or less than 40 micrometers and a height of equal to or more than 1.0 micrometer and equal to or less than 3.5 micrometers, for example. A distance (arrangement pitch) P between adjacent dot spacers27in the CD directions or the EF directions is, for example, equal to or more than 2 millimeters and equal to or less than 4 millimeters.

The dot spacers27are not necessarily provided on the insulating substrate21(the second base20), and may be provided on the insulating substrate11(the first base10) instead. The dot spacers27are also not necessarily arrayed in a matrix at substantially regular intervals. For example, an arrangement pitch P2between the dot spacers27on the inter-substrate connecting wire electrodes23,24or the wire electrodes25,26may be made smaller than an arrangement pitch P1between the dot spacers27on the second resistance film22as illustrated inFIG. 5. This arrangement can more surely suppress unwanted contact between the inter-substrate connecting wire electrodes23,24or the wire electrodes25,26and the first resistance film12, while maintaining a state in which the first resistance film12and the second resistance film22can come into contact with each other appropriately at a predetermined position. Therefore, the occurrence of electrical failures in the touch panel X1can be suppressed more surely. In particular, setting the arrangement pitch P2to be equal to or less than 200 micrometers can further enhance the above-described advantageous effects.

The dot spacers27can be formed, for example, with thermosetting resins or ultraviolet curing resins and by screen printing, offset printing, or photolithography. Using thermosetting resins as the component material of the dot spacers27can enhance heat resistance, chemical resistance, and other environment resistance properties, thereby ensuring high long-term reliability, for example. Examples of such thermosetting resins include epoxy resins, unsaturated polyester resins, urea resins, melanine resins, and phenol resins. On the other hand, using ultraviolet curing resins as the component material of the dot spacers27can, for example, shorten curing time compared with the use of the thermosetting resins, thereby further enhancing manufacturing efficiency. Examples of the ultraviolet curing resins include acrylic resins and epoxy resins.

The dot spacers27may be configured to contain insulating particles. This configuration can enhance the shape stability of the dot spacers27without unnecessarily lowering their electrical insulation properties, thereby maintaining the functions of the dot spacers27for a longer period of time.

An example of a method for forming the dot spacers27will now be described. The following description uses a thermosetting resin as the component material of the dot spacers27, and the dot spacers27are formed on the insulating substrate21(the second base20).

First, a printing plate is disposed on the insulating substrate21in an aligned manner. The second resistance film22, the inter-substrate connecting wire electrodes23,24, and the wire electrodes25,26are provided on the insulating substrate21in advance. The printing plate has predetermined openings. The openings are formed at predetermined intervals (intervals determined depending on desired arrangement pitches) in facing areas facing the second resistance film22, predetermined areas of the inter-substrate connecting wire electrodes23,24except for their respective one ends (the area located in the externally conductive area20aof the second base20) and their respective other ends (the adhesion area effected by the electrically conductive adhesive member30), and predetermined areas of the wire electrodes25,26except for their respective one ends (the area located in the externally conductive area20aof the second base20).

A thermosetting resin is then printed in predetermined areas on the insulating substrate21through the openings of the printing plate. Consequently, the insulating substrate21is applied with the thermosetting resin in a manner corresponding to the arrangement of the openings. After the printing plate is removed from the insulating substrate21, the insulating substrate21is heated up to the curing temperature of the thermosetting resin to cure the thermosetting resin. Accordingly, the thermosetting resin is transformed into hemispheres until the thermosetting resin is cured, and is cured in the shape of hemispheres. The dot spacers27in the shape of hemispheres are thus provided at predetermined positions on the insulating substrate21.

In the touch panel X1, the dot spacers27are interposed in at least a part of the facing areas where the inter-substrate connecting wire electrodes23,24or the wire electrodes25,26face the first resistance film12. Therefore, the touch panel X1can suppress unwanted contact between the inter-substrate connecting wire electrodes23,24or the wire electrodes25,26and the first resistance film12even when external force (e.g., pressing force to make inputs with the touch panel) is applied to the touch panel X1, thereby suppressing the occurrence of electrical failures.

In the touch panel X1, the same spacers as those interposed in a facing area (first facing area) between the first resistance film12and the second resistance film22are interposed in another facing area (second facing area) between the inter-substrate connecting wire electrodes23,24or the wire electrodes25,26and the first resistance film12. Thus, the spacers interposed in the second facing area can be provided in the same process as that for forming the spacers interposed in the first facing area in the touch panel X1. Therefore, the manufacturing efficiency of the touch panel X1can be enhanced compared with counterparts to suppress unwanted contact between the inter-substrate connecting wire electrodes23,24or the wire electrodes25,26and the first resistance film12in the second facing area by devising the shape of the first resistance film12through patterning.

The dot spacers27in the touch panel X1are provided to one of the first base10(the insulating substrate11) and the second base20(the insulating substrate21). Therefore, by using a predetermined printing plate to print and provide the dot spacers27in the touch panel X1, the dot spacers27interposed in both the first facing area and the second facing area can be provided all at once with a single printing plate. The touch panel X1thus requires no replacement of a plurality of printing plates, and the manufacturing efficiency of the touch panel X1can be enhanced accordingly.

As shown inFIGS. 6A and 6B, the electrically conductive adhesive member30serves to join the first base10and the second base20, while ensuring electrical conductivity between the first resistance film12and the inter-substrate connecting wire electrodes23,24. The electrically conductive adhesive member30includes first particles31, second particles32, and an adhesive material33.

The electrically conductive adhesive member30is disposed in an area in which the first resistance film12is provided and to surround an area in which the second resistance film22is provided as viewed in a plan view (viewed in the AB directions). This arrangement reduces the intrusion of foreign matters in the facing area between the first resistance film12and the second resistance film22. Note that the shape in which the electrically conductive adhesive member30is disposed is not limited to a frame to surround the second resistance film22, but various alternatives can be made.

The first particles31serve to electrically couple the first resistance film12and the inter-substrate connecting wire electrodes23,24, and at least a part of the first particles31is embedded in the electrically conductive adhesive member30. The first particles31are formed to be substantially spherical to reduce damages on the first resistance film12, the inter-substrate connecting wire electrodes23,24, and the like, which are in contact with the first particles31. Note that the shape of the first particles31is not limited to being substantially spherical, but may be, for example, polyhedral. As the first particles31, any materials at least having conductivity on their surfaces can be adopted, examples of which include spherical insulating members such as plastic balls having their surfaces coated with an electrically conductive material (e.g., gold, nickel).

The first particles31according to the present embodiment have a particle diameter D11in the AB directions before deformation (compression) (seeFIG. 6A) that is larger than a particle diameter D21of the second particles32in the AB directions before deformation (compression) (seeFIG. 6A), which means the first particles31are further compressed than the second particles32. The particle diameter D11of the first particles31before compression (seeFIG. 6A) is, for example, equal to or more than 2 micrometers and equal to or less than 25 micrometers. A particle diameter D12of the first particles31after compression (seeFIG. 6B) is, for example, equal to or more than 1.5 micrometers and equal to or less than 24 micrometers. The particle diameter D11of the first particles31before compression is not limited to the range above, as long as the diameter is within a range that ensures a sufficient contact area for the first resistance film12or the inter-substrate connecting wire electrodes23,24without excessively deforming the first particles31themselves.

The first particles31are further compressed than the second particles32as described above. In other words, the first particles31have a larger deformation rate (compression rate) D1defined by Formula 1 below and a larger aspect ratio L1defined by Formula 2 below than a deformation rate (compression rate) D2(see Formula 3) and an aspect ratio L2(see Formula 4), respectively, of the second particles32, which will be described later. The deformation rate (compression rate) D1of the first particles31is, for example, equal to or more than 0.03 and equal to or less than 0.3. The aspect ratio L1of the first particles31is, for example, equal to or more than 1.03 and equal to or less than 3.
D1=(D11−D12)/D11[Formula 1]D1: Deformation rate (Compression rate) of the first particlesD11: Particle diameter of the first particles in the AB directions before compressionD12: Particle diameter of the first particles in the AB directions after compression
L1=L11/L12[Formula 2]L11: Size in the long axis direction (Size in the EF directions inFIG. 6B)L12: Size in the short axis direction (Size in the AB directions inFIG. 6B)

While the first particles31are configured to come into direct contact with the first resistance film12, they are not limited to this configuration. For example, wiring similar to the inter-substrate connecting wire electrodes23,24may be provided on the insulating substrate11, so that, via this wiring, the first particles31and the insulating substrate11are electrically coupled.

The second particles32contribute to defining the distance between the first base10and the second base20, and at least a part of the second particles32is embedded in the electrically conductive adhesive member30. The second particles32are formed to be substantially spherical for a similar reason to that described above for the first particles31. Note that the shape of the second particles32is not limited to being substantially spherical, but may be, for example, polyhedral. As the second particles32, silica balls (spherical particles mainly made of silicon dioxide) are adopted because they are able to easily define the distance between the first base10and the second base20. Instead, glass fiber or other materials may be used for the second particles32.

The second particles32according to the present embodiment have the particle diameter D21before compression (seeFIG. 6A) that is smaller than the particle diameter D11of the first particles31before compression (seeFIG. 6A), which means the second particles32are less compressed (scarcely compressed) than the first particles31. The particle diameter D21of the second particles32before compression (seeFIG. 6A) and a particle diameter D22of the second particles32after compression are, for example, equal to or more than 1.5 micrometers and equal to or less than 24 micrometers. The particle diameters D21, D22of the second particles32before and after compression, respectively, are not limited to this range, as long as the diameters make the distance between the first base10and the second base20fall within a target range.

The second particles32also have a smaller deformation rate (compression rate) D2defined by Formula 3 below and a smaller aspect ratio L2defined by Formula 4 below than the deformation rate (compression rate) D1(see Formula 1 above) and the aspect ratio L1(see Formula 2 above), respectively, of the first particles31. The deformation rate (compression rate) D2of the second particles32is, for example, equal to or more than 0 and equal to or less than 0.01. The aspect ratio L2of the second particles32is, for example, equal to or more than 1 and equal to or less than 1.01.
D2=(D21−D22)/D21[Formula 3]D2: Deformation rate (Compression rate) of the second particlesD21: Particle diameter of the second particles in the AB directions before compressionD22: Particle diameter of the second particles in the AB directions after compression
L2=L21/L22[Formula 4]L21: Size in the long axis direction (Size in the EF directions inFIG. 6B)L22: Size in the short axis direction (Size in the AB directions inFIG. 6B)

The adhesive material33contributes to joining the first base10and the second base20, and is mixed with the first particles31and the second particles32. Examples of the adhesive material33include thermosetting resins, e.g., epoxy resins, and ultraviolet curing resins, e.g., acrylic resins. In particular, thermosetting resins are preferably used as the adhesive material33from the viewpoint of work efficiency in manufacturing processes.

The touch panel X1is configured to include two types of particles composed of the first particles31and the second particles32in the electrically conductive adhesive member30, but is not limited thereto. Alternatively, only the first particles31may be included, which requires preparation of only one type of particles and is thus preferable in view of cost saving.

An example of a method for bonding the first base10and the second base20with the electrically conductive adhesive member30will now be described.

As the electrically conductive adhesive member30, the uncured adhesive material33with the first particles31and the second particles32mixed therein is used. The following description employs a thermosetting resin as the adhesive material33. As the first particles31, spherical insulating members such as plastic balls that have their surfaces coated with an electrically conductive material and are comparatively easy to deform are adopted. As the second particles, silica balls or the like that are comparatively difficult to deform are adopted. In other words, in comparison between the first particles31and the second particles32, the second particles32have a larger compressive elastic modulus than that of the first particles31. As the first particles31, those having a compressive elastic modulus of, for example, equal to or more than 300 kgf/mm2(approximately 2.9×103MPa) and equal to or less than 600 kgf/mm2(approximately 5.9×103MPa) are adopted. As the second particles32, those having a compressive elastic modulus of, for example, equal to or more than 1500 kgf/mm2(approximately 1.5×104MPa) and equal to or less than 25000 kgf/mm2(approximately 2.5×105MPa) are adopted.

Note that the compressive elastic moduli of the first particles31and the second particles32mean so-called 10% K-values that are defined by Formula 5 below.
10% K-value=(3/21/2)·F·S−3/2·R−1/2[Formula 5]F: Load value (Kgf) on particles with 10% compressional deformationS: Compressional transition (mm) of particles with 10% compressional deformationR: Radius (mm) of particles

Values F, S, and R for defining 10% K-values can be measured by compressing particles corresponding to the first particles31and the second particles32with a micro compression testing machine (model PCT-200, manufactured by Shimadzu Corporation) at room temperature. Such particles corresponding to the first particles31and the second particles32are compressed, for example, on a smooth end surface of a diamond column having a diameter of 50 micrometers at a compression rate of 0.27 gf/s and a maximum test weight of 10 gf.

Adhesion between the first base10and the second base20starts with printing (application) of the electrically conductive adhesive member30in a predetermined area on the upper surface of the second base20(the surface on which the inter-substrate connecting wire electrodes23,24are provided). The predetermined area according to the present embodiment is an area provided to surround the second resistance film22(i.e., the area surrounded by the dashed-two dotted line) as can be well seen inFIG. 1.

Next, as shown inFIG. 6A, the first base10is aligned with the second base20having the electrically conductive adhesive member30printed thereon, and the first base10and the second base20are bonded to each other with the electrically conductive adhesive member30therebetween, whereby a bonded structure is produced.

Next, as shown inFIG. 6B, pressure is applied to the first base10and the second base20included in the thus produced bonded structure in such directions that the both come close to each other. According to the present embodiment, the application of pressure is continued until the second particles32come into contact with both the first base10and the second base20, while the first particles31are deformed by the first base10and the second base20in such a manner to increase the deformation rate (compression rate) D1(see Formula 1) or the aspect ratio L1(see Formula 1) of the first particles31.

While the pressurized state is maintained, the electrically conductive adhesive member30is heated up to the curing temperature of the adhesive material33to cure the adhesive material33. The adhesive material33is thus cured, whereby the first base10and the second base20are bonded.

An example of a touch panel type display device according to the present invention will now be described with reference toFIGS. 7 to 9.

As shown inFIGS. 7 to 9, this touch panel type display device Y includes the touch panel X1and a liquid crystal display unit Z.

The touch panel X1is the one described above with reference toFIGS. 1 to 6. Elements like those inFIGS. 1 to 6have the same reference numerals inFIG. 7.

The liquid crystal display unit Z includes a liquid crystal display panel40, a backlight50, and a casing60.

The liquid crystal display panel40includes a liquid crystal layer41, a first base42, a second base43, and a sealing member44. The liquid crystal display panel40has a display area P configured to include a plurality of pixels to display images. The display area P is prepared by interposing the liquid crystal layer41between the first base42and the second base43and sealing the liquid crystal layer41with the sealing member44.

The liquid crystal layer41is a layer configured to contain liquid crystals, which have electrical, optical, mechanical, or magnetic anisotropy and have both the regularity of solid and the liquidity of liquid. Examples of such liquid crystals include nematic liquid crystals, cholesteric liquid crystals, and smectic liquid crystals. In the liquid crystal layer41, a large number of spacers (not shown) made of particle members may be interposed to keep the thickness of the liquid crystal layer41constant.

The first base42includes a translucent substrate421, a light shielding film422, color filters423, a planarizing film424, translucent electrodes425, and an alignment film426.

The translucent substrate421is a member that contributes to supporting the light shielding film422and the color filters423and sealing the liquid crystal layer41. The translucent substrate421is configured to be capable of making light pass therethrough appropriately in a direction (e.g., AB directions) intersecting its principal surface. Examples of the component material of the translucent substrate421include glass and translucent plastic.

The light shielding film422serves to shield light (to make the amount of light transmission equal to or less than a predetermined level), and is provided on the upper surface of the translucent substrate421. The light shielding film422has through-holes422athat penetrate the film in the film thickness direction (AB directions) to make light pass therethrough. Examples of the component material of the light shielding film422include resins (e.g., acrylic resins) and Cr added with dyes or pigments in highly light shielding colors (e.g., black) and carbon.

The color filters423serve to selectively absorb light having predetermined wavelengths among incident light on the color filters423, and selectively make light having predetermined wavelengths pass therethrough. Examples of the color filters423include a red color filter (R) to selectively make light having the wavelength of red visible light pass therethrough, a green color filter (G) to selectively make light having the wavelength of green visible light pass therethrough, and a blue color filter (B) to selectively make light having the wavelength of blue visible light pass therethrough. The color filters423are prepared by adding dyes or pigments to an acrylic resin, for example.

The planarizing film424serves to planarize the uneven surface caused by the disposition of the color filters423, for example. Examples of the component material of the planarizing film424include acrylic resins and other translucent resins.

The translucent electrodes425serve to apply a predetermined voltage to liquid crystals in the liquid crystal layer41disposed between themselves and translucent electrodes432of the second base43, which will be described later, and have translucency in a direction (e.g., AB directions) intersecting their principal surfaces. The translucent electrodes425serve to transmit predetermined signals (image signals), and are provided in plurality to extend mainly in the arrow CD directions. Examples of the component material of the translucent electrodes425include ITO, tin oxide, and other translucent electrically conductive members.

The alignment film426serves to align liquid crystal molecules of the liquid crystal layer41, which are oriented in random directions in a macroscopic perspective (with low regularity), in a predetermined direction, and is provided on the translucent electrodes425. Examples of the component material of the alignment film426include polyimide resins.

The second base43includes a translucent substrate431, the translucent electrodes432, and an alignment film433.

The translucent substrate431is a member that contributes to supporting the translucent electrodes432and the alignment film433and sealing the liquid crystal layer41. The translucent substrate431is configured to be capable of making light pass therethrough appropriately in a direction (e.g., arrow AB directions) intersecting its principal surface. The component material of the translucent substrate431can be the same as that of the translucent substrate421.

The translucent electrodes432serve to apply a predetermined voltage to liquid crystals in the liquid crystal layer41disposed between themselves and the translucent electrodes425of the first base42, and are configured to make incident light on one side pass therethrough to the other side. The translucent electrodes432serve to transmit signals (scanning signals) for controlling a voltage-applied state (ON) or no voltage-applied state (OFF) of the liquid crystal layer41, and are provided in plurality in such a manner to extend mainly in a direction perpendicular to the plane ofFIG. 9(e.g., EF directions inFIG. 1). The component material of the translucent electrodes432can be the same as that of the translucent electrodes425.

The alignment film433serves to align liquid crystal molecules of the liquid crystal layer41, which are oriented in random directions in a macroscopic perspective (with low regularity), in a predetermined direction, and is provided on the translucent electrodes432. The component material of the alignment film433can be the same as that of the alignment film426.

The sealing member44serves to seal the liquid crystal layer41between the first base42and the second base43, and join the first base42and the second base43with the both spaced at a predetermined interval. Examples of the sealing member44include insulating resins and sealing resins.

The backlight50serves to emit light from one side of the liquid crystal display panel X1to the other side, and employs an edge light unit. The backlight50includes a light source51and a light guide plate52. The light source51serves to emit light toward the light guide plate52, and is disposed on a side of the light guide plate52. Examples of the light source51include CFL

(Cathode Fluorescent Lamp), LED (Light Emitting Diode), halogen lamp, xenon lamp, and EL (electro-luminescence). The light guide plate52serves to guide light emitted by the light source51substantially evenly in the whole lower surface of the liquid crystal display panel40. The light guide plate52typically includes a reflection sheet, a diffusion sheet, and a prism sheet. The reflection sheet (not shown) serves to reflect light and is provided on the back surface. The diffusion sheet (not shown) serves to diffuse light to achieve more even surface light emission and is provided on the front surface. The prism sheet (not shown) serves to collimate light in a substantially constant direction and is provided on the front surface. Examples of the component material of the light guide plate52include acrylic resins, polycarbonate resins, and other translucent resins. The backlight50is not limited to the edge light unit with the light source51disposed on a side of the light guide plate52, and other alternative types, such as a direct backlight unit with the light source51disposed on the back surface side of the liquid crystal display panel40, can be used instead.

The casing60serves to house the liquid crystal display panel40and the backlight50, and is configured to include an upper casing61and a lower casing62. Examples of the component material of the casing60include: resins, such as polycarbonate resins; metals, such as aluminum; and alloys, such as stainless (SUS).

An example of a method for fixing the touch panel X1and the liquid crystal display unit Z with a double-faced adhesive tape T will now be described. Note that a fixing member used in the method for fixing the touch panel X1and the liquid crystal display unit Z is not limited to the double-faced adhesive tape T. Adhesive members, such as thermosetting resins and ultraviolet curing resins, may be used, and other fixing structures for physically fixing the touch panel X1and the liquid crystal display unit Z may be used, for example.

One side of the double-faced adhesive tape T is attached to a predetermined area on the upper surface of the upper casing61included in the liquid crystal display unit Z. According to the present embodiment, the predetermined area is an area R located to surround the display area P of the liquid crystal display unit Z as well illustrated inFIG. 8.

Then, with the touch panel X1aligned with the liquid crystal display unit Z to which the double-faced adhesive tape T is attached, the insulating substrate21included in the touch panel X1and the upper casing61included in the liquid crystal display unit Z are bonded to each other with the double-faced adhesive tape T therebetween. Accordingly, the touch panel X1and the liquid crystal display unit Z are fixed to each other.

Including the touch panel X1, the touch panel type display device Y has the same advantageous effects as those of the touch panel X1. Specifically, the touch panel type display device Y can suppress unwanted contact between the resistance films11,12and the inter-substrate connecting wire electrodes23,24or the wire electrodes25,26even when external force (e.g., pressing force to make inputs with the touch panel) is applied to the touch panel X1. Furthermore, the manufacturing efficiency of the touch panel type display device Y can be enhanced compared with counterparts to devise the shape of the first resistance film12through patterning.

A touch panel according to a second embodiment of the present invention will now be described with reference toFIGS. 10 to 12. Elements like those of the touch panel according to the first embodiment described with reference toFIGS. 1 to 6have the same reference numerals in these drawings, and thus repeated descriptions will be omitted.

FIGS. 10 to 12are sectional views of principal components of this touch panel X2. The touch panel X2illustrated in these drawings can be, like the touch panel X1according to the first embodiment (seeFIGS. 1 to 6), combined with the liquid crystal display unit Z to be applied to the touch panel type display device Y (seeFIGS. 7 to 9).

The touch panel X2differs from the touch panel X1according to the first embodiment (seeFIGS. 1 to 6) in that the dot spacers27arrayed in predetermined areas of the inter-substrate connecting wire electrodes23,24except for their respective one ends (the area located in the externally conductive area20aof the second base20) and their respective other ends (the adhesion area effected by the electrically conductive adhesive member30) and in predetermined areas of the wire electrodes25,26except for their respective one ends (the area located in the externally conductive area20aof the second base20) are replaced with insulating layers28.

The insulating layers28serve to reduce the occurrence of unwanted electrical contact between the inter-substrate connecting wire electrodes23,24or the wire electrodes25,26and the first resistance film12. The insulating layers28are provided to cover predetermined areas of the inter-substrate connecting wire electrodes23,24except for the area located in the externally conductive area20aand the adhesion area effected by the electrically conductive adhesive member30. The insulating layers28are also provided to cover predetermined areas of the wire electrodes25,26except for the area located in the externally conductive area20a.

The component material of the insulating layers28can be the same as that of the dot spacers27. More specifically, examples of the component material of the insulating layers28include: thermosetting resins, such as epoxy resins, unsaturated polyester resins, urea resins, melanine resins, and phenol resins; and ultraviolet curing resins, such as acrylic resins and epoxy resins. The thickness of the insulating layers28is preferably more than 0 micrometer and equal to or less than 10 micrometers in view of the flatness of the touch panel X2.

An example of a method for forming the dot spacers27and the insulating films28will now be described. In the following description, a case is assumed where a thermosetting resin is used as the component material of the dot spacers27and the insulating films28, and the dot spacers27are formed on the insulating substrate21.

First, a printing plate is disposed on the insulating substrate21in an aligned manner. The second resistance film22, the inter-substrate connecting wire electrodes23,24, and the wire electrodes25,26are provided on the insulating substrate21in advance. The printing plate has first openings for forming the dot spacers27and second openings for forming the insulating films28. The first openings are formed at predetermined intervals (intervals determined depending on desired arrangement pitches) in a facing area facing the second resistance film22. The second openings are formed wholly in facing areas facing predetermined areas of the inter-substrate connecting wire electrodes23,24except for their respective one ends (the area located in the externally conductive area20aof the second base20) and their respective other ends (the adhesion area effected by the electrically conductive adhesive member30), and predetermined areas of the wire electrodes25,26except for their respective other ends (the area located in the externally conductive area20aof the second base20).

A thermosetting resin is then printed in predetermined areas on the insulating substrate21through the first and second openings of the printing plate. Consequently, the insulating substrate21is applied with the thermosetting resin in a manner corresponding to the arrangement of the first and second openings. After the printing plate is removed from the insulating substrate21, the insulating substrate21is heated up to the curing temperature of the thermosetting resin to cure the thermosetting resin. Accordingly, the dot spacers27and the insulating layers28are provided at predetermined positions on the insulating substrate21.

The touch panel X2includes the insulating films28interposed in the substantially whole area (the whole area except for areas where electrical conductivity is achieved, e.g., electrically conductive parts) of the facing areas where the inter-substrate connecting wire electrodes23,24or the wire electrodes25,26face the first resistance film12. Accordingly, the touch panel X2can sufficiently suppress unwanted contact between the inter-substrate connecting wire electrodes23,24or the wire electrodes25,26and the first resistance film12even when external force (e.g., pressing force to make inputs with the touch panel) is applied to the touch panel X2. The touch panel X2thus can sufficiently suppress the occurrence of electrical failures.

The component material of the insulating films28is the same as that of the dot spacers27. Therefore, the insulating films28in the touch panel X2can be formed in the same process as that for forming the dot spacers27without any additional processes for forming the insulating films28. The touch panel X2, therefore, requires no additional process for forming the insulating films28, and the manufacturing efficiency of the touch panel X2can be enhanced accordingly.

The insulating films28as well as the dot spacers27in the touch panel X2are provided to the same base (the second base20(the insulating substrate21) according to the present embodiment). Therefore, the insulating films28and the dot spacers27in the touch panel X2can be provided all at once with a single printing plate. The touch panel X2thus requires no replacement of a plurality of printing plates to form the dot spacers27and the insulating films28, and the manufacturing efficiency of the touch panel X2can be enhanced accordingly.

While specific embodiments of the present invention are described above, the present invention is not limited thereto, and various modifications can be made without departing from the spirit of the invention.

The touch panels X1, X2may also include a phase difference film arranged on at least one of the first base10and the second base20. The phase difference film is an optical compensation member to convert linear polarized light that has been converted into an elliptical polarization state due to, for example, birefringence of liquid crystals (phase misalignment) into a state closer to linear polarized light from the elliptical polarization state. Examples of the component material of the phase difference film include polycarbonate (PC), polyvinyl alcohol (PVA), polyarylate (PA), polysulfone (Psu), and polyolefin (PO). In particular, as the component material of the phase difference film, PC is preferable in view of consistency with the wavelength dispersion of liquid crystals, and P0, which has a smaller photoelastic coefficient than PC, is preferable in view of adaptability to circularly polarizing plates.

The touch panels X1, X2may also include a polarizing film arranged on at least one of the first base10and the second base20. The polarizing film serves to selectively make light having a predetermined vibration direction pass therethrough. Examples of the component material of the polarizing film include iodine materials. Such a component is preferable to exert a function of shuttering light passing through the polarizing film.

The touch panels X1, X2may also include a film that has undergone anti-glare treatment or anti-reflection coating treatment arranged on at least one of the first base10and the second base20. This arrangement can reduce reflection of ambient light.

The insulating substrates11,12of the touch panels X1, X2may be replaced with any of a phase difference film, a polarizing film, and a film that has undergone anti-glare treatment or anti-reflection coating treatment.

While the electrically conductive adhesive member30is provided by a single application to surround the whole of the second resistance film22in the touch panels X1, X2, the present invention is not limited thereto. For example, the electrically conductive adhesive member30may be configured to have a through-hole communicating an inner part located on the inner side of the electrically conductive adhesive member30and an outer part located on the outer side of the electrically conductive adhesive member30. In this case, after the electrically conductive adhesive member30is applied and the first base10and the second base20are bonded thereby, the air or the like can be injected into the inner part located on the inner side of the electrically conductive adhesive member30through the through-hole. The through-hole can be sealed with a similar material to the electrically conductive adhesive member30or an electrically non-conductive adhesive member (e.g., an ultraviolet curing resin) after the injection of the air or the like.

While the insulating layers28are provided to wholly cover predetermined areas of the inter-substrate connecting wire electrodes23,24except for their respective one ends (the area located in the externally conductive area20aof the second base20) and their respective other ends (the adhesion area effected by the electrically conductive adhesive member30) and predetermined areas of the wire electrodes25,26except for their respective one ends (the area located in the externally conductive area20aof the second base20) in the touch panel X2; instead of this arrangement, the insulating layers28may be provided to partially cover the predetermined areas within a range to suppress unwanted contact between the inter-substrate connecting wire electrodes23,24or the wire electrodes25,26and the first resistance film12. This arrangement can reduce the usage amount of the insulating layers28, thereby saving weight and cost.

In configurations with the insulating layers28as in the present embodiment, the position where the through-hole is formed is not limited. By contrast, in configurations with no insulating layers28, it is preferable to adopt a configuration in which the through-hole is formed in an area where an electrically conductive adhesive member intersects with leading lines of wires and the through-hole is sealed with an electrically non-conductive adhesive member (e.g., an ultraviolet curing resin) to suppress the occurrence of unwanted electrical conduction.