JP6104764B2 - Film for touch panel - Google Patents

Description

  The present invention relates to a film for a touch panel, for example, a capacitive touch panel film in which a position on a screen touched by an indicator such as a finger or a stylus pen is obtained as coordinate information.

In recent years, in portable information terminals such as smartphones and tablet PCs that are rapidly spreading, a projection capacitive touch panel capable of multi-touch operation is often used.
The structure of the projected capacitive touch panel will be briefly described with reference to FIG. 12 (exploded view). The capacitive touch panel 50 shown in FIG. 12 has an indium tin oxide film (hereinafter referred to as an ITO film) having a plurality of electrodes for detecting coordinates in the Y direction on the back side of a transparent insulating film 53, for example. 51 is formed, and an ITO film 52 having a plurality of electrodes for detecting coordinates in the X direction is formed on the front side.

The ITO film 51 is provided with a plurality of rhombic electrode pads 54 (sensor electrodes) connected in the X direction and electrically connected to each other in the Y direction, and the ITO film 52 is formed in the Y direction. A plurality of rhombic electrode pads 55 (sensor electrodes) connected to each other and electrically connected to each other are provided in a plurality of rows in the X direction. Each of the electrode pads 54 and 55 has an area sufficient to generate a change in capacitance (about 1 pF) that can detect the contact position of an indicator (such as a finger or a stylus pen). The width is about 5 mm.
When the insulating film 53 on which the ITO films 51 and 52 are formed is viewed in plan, the electrode pads 54 and 55 have a two-dimensional lattice structure in which the electrode pads 54 and 55 are arranged in the plane direction with a predetermined gap as shown in FIG. ing.

When, for example, a fingertip is brought into contact with the touch panel 50 through a cover glass (not shown), the capacitance of the electrode pad 54 at the contact position among the electrode pads 54 connected in the X direction becomes a predetermined value or more. Change. Thereby, the coordinate position in the Y direction is detected.
In addition, among the electrode pads 55 connected in the Y direction, the capacitance of the electrode pad 55 at the contact position changes to a predetermined value or more. Thereby, the coordinate position in the X direction is detected.

By the way, the capacitance type touch panel 50 cannot detect the position unless the capacitance (about 1 pF) is changed more than a predetermined value at the contact point by the finger or the stylus pen as described above. . For this reason, conventionally, an input operation to the capacitive touch panel is performed with a conductive stylus pen or a fingertip that can be contacted with a contact area larger than the area of the electrode pads 54 and 55, and the static operation necessary for position detection is performed. The capacitance is changed (if the contact area is small, the capacitance required for position detection does not change).
For example, Patent Document 1 discloses a prior art regarding a projected capacitive touch panel.

JP 2008-310551 A

However, when inputting to a capacitive touch panel using the conductive stylus pen, the pen tip is thick (for example, 5 mm in diameter (contact area is about 19.6 mm ² ) or more) as described above. Therefore, there has been a problem that operability, visibility during operation, and usability are impaired.
In order to solve the above-mentioned problem, it is conceivable to simply subdivide the sensor electrodes of the touch panel and reduce the amount of change in capacitance that can be detected in each sensor electrode. There has been a problem that detection has to be performed and there is a greater risk of erroneous detection.
Further, when the sensor electrodes are subdivided, the number of electrodes increases, so that the amount of calculation for obtaining the touch position greatly increases. Therefore, when the processing capability of the control unit that performs the calculation is insufficient, there is a problem that the touch position detection cannot follow the touch operation, the display is delayed, and the usability is reduced. In addition, when the processing capability of the control unit is improved so that the touch position detection can follow the touch operation, there are problems that the power consumption increases and the cost increases.

  The present invention has been made paying attention to the above points, and is provided on a capacitive touch panel in which the position on the screen touched by the indicator is obtained as coordinate information, and the contact area of the indicator has been conventionally An object of the present invention is to provide a film for a touch panel that can detect a contact position even when the contact area is smaller than that of the above case.

In order to solve the above-described problems, the touch panel film according to the present invention is a capacitive touch panel film interposed between a capacitive touch panel in which sensor electrodes are arranged and a conductive indicator. A transparent conductive thin film having a predetermined surface resistivity set in a range of 10 ^5.0 to 10 ^7.0 Ω / sq formed on the surface of the film, and laminated on the transparent conductive thin film When the indicator contacts the surface of the protective layer, the dielectric between the predetermined region including the contact position and the sensor electrode has 0 per unit area. It is characterized in that a change in capacitance of 0.52 to 5.96 pF / mm ² occurs.
When the indicator comes into contact with the surface of the protective layer, at least 1.11 pF / mm ² between the predetermined region including the contact position of the indicator and the transparent conductive thin film in the protective layer. It is desirable for the capacitance to change.
The thickness of the protective layer is preferably less than 30 μm.

When the indicator comes into contact with the film having at least the transparent conductive thin film having the predetermined surface resistivity set in the range of 10 ^5.0 to 10 ^7.0 Ω / sq as described above, the predetermined position including the contact position is included. Since a change in capacitance of 0.52 to 5.96 pF / mm ² per unit area occurs in the dielectric between the region and the sensor electrode, the contact area of the indicator is the sensor electrode constituting the touch panel Even if it is smaller than the area, it is possible to achieve a contact state equivalent to a human finger.
That is, even if the contact area of the indicator is small, it is possible to cause a change in electrostatic capacitance within a predetermined range between the indicator that contacts the film surface and the sensor electrode, and the contact position of the indicator is detected. can do.
For this reason, for example, the touch panel can be operated with a stylus pen having a thin pen tip, and operability, visibility during operation, and usability can be improved.

Moreover, since the structure of a touch panel can employ | adopt the conventional structure, the increase in the cost concerning manufacture can be suppressed.
Furthermore, since the transparent protective layer is formed on the transparent conductive thin film, the transparent conductive thin film can be protected, and a film for a touch panel excellent in durability (abrasion resistance) can be obtained. .

Moreover, the said protective layer is good also as a structure containing a ultraviolet absorber.
That is, when a transparent conductive thin film is formed using, for example, a conductive polymer typified by polythiophene, the protective layer on the front side of the protective layer on the front side has an ultraviolet ray because the conductivity deteriorates when exposed to ultraviolet rays. By including an absorbent, it is possible to prevent deterioration of the transparent conductive thin film.

  According to the present invention, the position on the screen touched by the indicator is provided on the capacitive touch panel obtained as coordinate information, and the contact area of the indicator is smaller than the conventional contact area. It is possible to provide a film for a touch panel that can detect a contact position.

FIG. 1 is a cross-sectional view of a touch panel device provided with a film for a touch panel according to the present invention. FIG. 2 is a cross-sectional view illustrating a configuration for explaining an effect that an actual contact area is increased in a pseudo manner when an indicator having conductivity is brought into contact with a high-resistance film. FIG. 3 is an equivalent circuit of the integration circuit generated in the high resistance film shown in FIG. FIG. 4 is a side view showing the tip of a stylus pen that can be used in the film for a touch panel according to the present invention. 5 is a cross-sectional view schematically showing a state in which the stylus pen of FIG. 4 is brought into contact with the touch panel film of FIG. FIG. 6 is a plan view schematically showing a state where the transparent conductive thin film included in the film for a touch panel according to the present invention is divided into a plurality of small sections insulated from each other. FIG. 7 is a perspective view schematically showing the apparatus configuration used in Experiment 4 of the example. FIG. 8 is a cross-sectional view schematically showing the configuration of the high resistance film used in the apparatus of FIG. FIG. 9 is a graph showing the results of Experiment 4 of the example, and is a graph showing the change in the capacitance of the entire film with respect to the thickness of the protective layer. FIG. 10 is a cross-sectional view schematically showing a capacitance measurement site measured in the example. FIG. 11 is a graph showing the results of Experiment 4 of the example, and is a graph showing changes in the capacitance of the protective layer with respect to the thickness of the protective layer. FIG. 12 is an exploded view schematically showing a configuration of a conventional touch panel. 13 is a plan view schematically showing sensor electrodes of the touch panel of FIG.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a touch panel device provided with a film for a touch panel according to the present invention.

  The touch panel device 1 in FIG. 1 is provided with a touch panel 3 on an LCD unit 2 which is a liquid crystal display device, and a high resistance film 5 as a touch panel film via a cover glass 4 which is a dielectric. Is provided. In the present embodiment, in order to attach the high resistance film 5 on the cover glass 4, the high resistance film 5 has at least an adhesive layer 9 in its lowermost layer.

  The touch panel 3 has sensor electrodes made of an ITO film on the front and back surfaces of a transparent insulating film 10 (corresponding to the insulating film 53 in FIG. 12), for example, similarly to the configuration shown in FIG. Specifically, a plurality of electrode pads 11 (corresponding to the electrode pad 55 in FIG. 12) are formed on the front side of the insulating film 10, and a plurality of electrode pads 12 (corresponding to the electrode pad 54 in FIG. 12) are formed on the back side. ing. Each of the electrode pads 11 and 12 is formed in a rhombus shape as in the conventional configuration of FIGS. 11 and 12, thereby constituting a two-dimensional lattice sensor electrode (similar to the configuration of FIG. 13). . Further, the width of the diagonal line of each electrode pad 11, 12 is, for example, 5 mm, and the indicator (finger or conductive stylus pen) on the electrode pad 11, 12 is changed by a change in predetermined capacitance (for example, about 1 pF). Etc.) can be detected.

The high-resistance film 5 is a transparent laminated film, and includes a PET film 8, a high-resistance transparent conductive thin film 7 formed on the PET film 8, and a protection formed on the transparent conductive thin film 7. Layer 6. Furthermore, an adhesive layer 9 is provided in the lower layer of the PET film 8.
The PET film 8 is a polyethylene terephthalate film formed to have a predetermined thickness (for example, about 50 μm), and is excellent in transparency, heat resistance, electrical insulation, and the like.
The transparent conductive thin film 7 is formed on the upper surface of the PET film 8 by, for example, forming an ITO film by sputtering or the like, or by forming a transparent conductive resin by coating or the like. The
The transparent conductive thin film 7 has a high resistance with a surface resistivity set in the range of 10 ⁵ to 10 ⁷ Ω / sq. Such a high surface resistance transparent conductive thin film 7 can be obtained by, for example, a method of increasing the resistivity by reducing the film thickness of a conductive polymer represented by ITO film or polythiophene having low resistance, or conductivity. Low conductive grade of conductive polymer represented by PEDOT-PSS aqueous solution consisting of polymer PEDOT (poly (3,4-ethylenedioxythiophene)) and polyanion PSS (polystyrene sulfonate) It can be obtained by forming a film uniformly on the top.

The protective layer 6 has a thickness dimension of less than 30 μm and is formed of a transparent resin film having high scratch resistance.
Specifically, when the protective layer 6 is formed, a commercially available hard coat agent, for example, trade name: Acier-PMMA (manufactured by Nidec Co., Ltd.), or trade name: purple light UV7600B (Nippon Synthetic Chemical) (Manufactured by Kogyo Co., Ltd.) can be obtained by uniformly coating the transparent conductive thin film 7 on the transparent conductive thin film 7 using a spin coater or bar coater and then curing it with UV light (ultraviolet light).
The protective layer 6 may contain a UV (ultraviolet) absorber. That is, when the transparent conductive thin film 7 is formed using, for example, a conductive polymer typified by polythiophene, the conductivity deteriorates when exposed to UV light (ultraviolet rays). When a certain protective layer 6 contains a UV absorber, deterioration of the transparent conductive thin film 7 can be prevented.
In addition, as a material of the protective layer 6 containing a UV absorber, for example, Rio Duras (registered trademark) TYN or TYT manufactured by Toyo Ink Co., Ltd. can be used.
Besides this, use inorganic UV absorbers containing general titanium oxide and zinc oxide, or organic UV absorbers such as benzotriazole, triazine, benzophenone and benzoate. Can do.

In addition, the adhesive layer 9 is formed to have a predetermined thickness (for example, 10 μm in thickness) from, for example, an acrylic material, a urethane material, a silicone material, or a rubber material, and has an appropriate adhesive force and high transparency and removability. have.
The adhesive layer 9 can be formed on the lower surface of the PET film 8 by bar coating, spin coating, spray coating, or the like.

The surface resistivity of the transparent conductive thin film 7 is within the range of 10 ⁵ to 10 ⁷ Ω / sq. The thickness of the protective layer 6, the cover glass 4, the PET film 8, the adhesive layer 9, etc., and the relative dielectric constant Accordingly, the change in capacitance per unit area that occurs between the predetermined region in contact with the indicator and the sensor electrode is set to be in the range of 0.52 to 5.96 pF / mm ^2. Yes.

  Next, by providing the high resistance film 5 on the cover glass 4, an effect that the actual contact area is increased in a pseudo manner when a conductive indicator is brought into contact with the high resistance film 5 is obtained. The principle that can be done will be described. Here, a case where a protective layer is not provided will be described as an example.

As shown in FIG. 2, a film 20 formed of a transparent conductive thin film 21 having a uniform predetermined surface resistivity, a PET film 22 and an adhesive layer 23 is prepared, and on the adhesive layer 23 side, An electrode 25 having an area larger than that of the film 20 is arranged, and a tip (electrode 26) of a conductive indicator having an area smaller than that of the film 20 is brought into contact with the transparent conductive thin film 21.
At this time, the film 20 sandwiched between the electrodes 25 and 26 can be replaced with an equivalent circuit as shown in FIG. That is, the film 20 has a resistance R (R1, R2, R3,..., Rn, Rn + 1,...) And a capacitance C (C1, C2, C3,..., Cn, Cn + 1,. ..) Are distributed (n is a positive integer value).
Here, the time constant τ of the integration circuit is expressed by the following equation (1). As the n of Cn increases (the area increases), the combined value of the resistors connected in series increases and the time constant τ of Cn increases. Will grow.

(Equation 1)
τ = R × C (1)
If the time constant τ becomes too large, Cn can hardly store charges in a short time. Therefore, C1 to Cn-1 are regarded as a range in which capacitance is accumulated.

  In such an integration circuit, if the surface resistivity R of the transparent conductive thin film 21 is reduced, the time constant τ is reduced from the equation (1). Therefore, the Cn at the boundary where the electrostatic capacity can be accumulated can be increased to Cn + 1, Cn + 2,..., And the pseudo area can be expanded.

  In general, the capacitance C can be defined by the following equation (2). Therefore, the time constant τ is also affected by the relative dielectric constant and thickness dimension of the PET film 22.

(Equation 2)
C = ε _r · ε ₀ × S / d (2)
ε _r : relative dielectric constant ε ₀ : vacuum dielectric constant d: dielectric thickness S: electrode area

Next, the configuration of a stylus pen that can be used with the high resistance film 5 (film for touch panel) shown in FIG. 1 will be described with reference to FIG.
FIG. 4 is a side view showing the tip of the stylus pen 30.
The stylus pen 30 shown in FIG. 4 has a pen tip 31 formed of a conductive material (for example, steel, copper, conductive rubber, conductive fiber, etc.), and a pen tip holder 32 that holds the pen tip 31. . On the rear end side from the pen tip holder 32, a grip portion, a pen shaft main body, and the like (both not shown) are provided.

  The pen tip holder 32, the grip portion, the pen shaft main body, and the like are made of a conductive material (for example, an aluminum alloy) electrically connected to the pen tip 31 so as to electrically couple the human body and the pen tip 31. Is formed. Alternatively, for example, a metal conduction portion (not shown) in which a hand (finger) of a pen user (human body) is in contact with the surface of the pen tip holder 32, the grip portion, the pen shaft main body, or the like is used. You may provide in the state electrically connected with 31.

The tip width dimension d1 of the pen tip 31 is formed to be smaller than the width of the diagonal lines (for example, 5 mm) of the electrode pads 11 and 12 of the touch panel 3.
The stylus pen used with the high resistance film 5 (touch panel film) shown in FIG. 1 is not limited to the shape shown in FIG. That is, when the pen user uses the stylus pen 30 in his / her hand, the tip user is provided with a pen tip which is formed of at least a conductive material and whose tip width is smaller than the width of the electrode pads 11 and 12. It is sufficient if the hand and the pen tip are electrically coupled.

  According to the stylus pen 30 and the touch panel device 1 configured as described above, even if the pen tip 31 of the stylus pen 30 is narrower than the width of the electrode pads 11 and 12, the pen tip 31 is made of the high resistance film 5. The contact position can be detected by contacting the surface.

That is, as shown in FIG. 5, when the stylus pen 30 contacts the high resistance film 5, the transparent conductive thin film 7 of the high resistance film 5 has a surface resistivity set in the range of 10 ⁵ to 10 ⁷ Ω / sq. Therefore, the contact area of the stylus pen 30 that is a conductor is pseudo-expanded, which is equivalent to a case where a human fingertip is in contact.

Thereby, as shown in FIG. 5, between the predetermined area | region including the contact position of the nib 31 of the stylus pen 30 and the electrode pad 11 (the protective layer 6, which is a dielectric, the cover glass 4, the PET film 8, the adhesive layer) 9), a predetermined capacitance change per unit area (about 0.52 to 5.96 pF / mm ² ) occurs (the protective layer 6 has a capacitance of at least 1.11 pF / mm ² or more). Change).
The capacitance generated between the predetermined area including the contact position of the pen tip 31 and the electrode pad 11 flows as a weak current (for example, 10 μA to 20 μA) to the human body via the stylus pen 30, thereby Among the contact positions of the pen tip 31 of the stylus pen 30, for example, a vertical coordinate position (a position in the Y direction in FIGS. 12 and 13) is detected.

Further, as in the case of the electrode pad 11 and the predetermined area including the contact position of the pen tip 31, the predetermined area including the contact position of the pen tip 31 of the stylus pen 30 and the electrode pad 12 (protection that is a dielectric). Layer 6, cover glass 4, PET film 8, adhesive layer 9) also has a predetermined change in capacitance per unit area (about 0.52 to 5.96 pF / mm ² ) (in protective layer 6, A capacitance change of at least 1.11 pF / mm ² or more occurs).
The electrostatic capacitance generated between the predetermined area including the contact position of the pen tip 31 and the electrode pad 12 flows as a weak current (for example, 10 μA to 20 μA) to the human body via the stylus pen 30, thereby Among the contact positions of the pen tip 31 of the stylus pen 30, for example, a horizontal coordinate position (a position in the X direction in FIGS. 12 and 13) is detected.

As described above, according to the embodiment of the present invention, the transparent conductive thin film 7 whose surface resistivity is set in the range of 10 ⁵ to 10 ⁷ Ω / sq on the touch panel 3 via the cover glass 4. Therefore, even if the contact area of the stylus pen 30 is smaller than the area of the electrode pads 11 and 12 constituting the touch panel 3, the contact area can be increased in a pseudo manner. For example, a predetermined capacitance change per unit area (a predetermined area) between the electrode pad 11 and the predetermined region on the protective layer 6 of the high resistance film 5 with which the pen tip 31 of the stylus pen 30 is in contact. About 0.52 to 5.96 pF / mm < ² >), so that a contact state equivalent to a human finger can be obtained.
That is, even if the contact area of the pen tip 31 of the stylus pen 30 is small, the dielectric between the pen tip 31 and the electrode pads 11 and 12 in contact with the surface of the high resistance film 5 is necessary for the reaction of the touch panel 3. The capacitance can be changed, and the contact position of the stylus pen 30 can be detected.

For this reason, the touch panel device 1 can be operated by the stylus pen 30 with the thin pen tip 31, and operability, visibility during operation, and usability can be improved.
Moreover, since the structure of the touch panel 3 can employ | adopt the conventional structure, it can suppress the increase in the cost concerning manufacture.
Furthermore, since the protective layer 6 is formed on the transparent conductive thin film 7, the transparent conductive thin film 7 can be protected, and the high resistance film 5 excellent in durability (abrasion resistance) can be obtained. it can.

In the embodiment described above, the touch panel 3 has a configuration in which a plurality of electrode pads 11 and a plurality of electrode pads 12 are formed as sensor electrodes on the front and back surfaces of the insulating film 10, respectively. However, it is not limited to the configuration.
For example, the electrode pad 11 and the electrode pad 12 made of an ITO film may be formed on separate transparent thin film insulating films, and the touch panel 3 may be configured by overlapping them. Alternatively, as long as the electrode pad 11 and the electrode pad 12 are electrically insulated, they may be formed on the same layer.

Moreover, in the said embodiment, although demonstrated that the high resistance transparent conductive thin film 7 which comprises the high resistance film 5 was uniformly formed in the whole film surface, as shown in FIG. It may be divided into a plurality of small sections (small section electrodes Ar).
In such a configuration, when the pen tip 31 of the stylus pen 30 contacts the surface of the high-resistance film 5, the contact position and the sensor electrode (electrode) in the region of the small partition electrode Ar corresponding to the contact position. A change in capacitance necessary for the reaction of the touch panel 3 can be generated between the pads 11 and 12).
That is, even if the tip diameter (contact area) of the stylus pen 30 is small, the touch panel can be reacted in the area of the small partition electrode at the contact position, so that the touch panel operation can be performed even with the stylus pen 30 with a thin pen tip. It becomes possible.
In addition, although each small division electrode Ar shown in FIG. 6 was made into the square shape divided | segmented into the vertical and horizontal grid | lattice form, you may form each small division electrode Ar not only in a square shape but in other shapes, The small partition electrodes Ar may have different sizes and shapes.

  Moreover, in the said embodiment, although the transparent conductive thin film 7 demonstrated as what is formed, for example by an ITO film | membrane etc., what kind of material will be used if it has not only that but transparency and electroconductivity. May be formed.

In the embodiment, the transparent conductive thin film 7 is formed on the upper surface of the PET film 8, but not only the PET film 8, but a film having excellent transparency and electrical insulation, Those formed of other materials may be used in place of the PET film 8.
The transparency in the transparent conductive thin film 7, the protective layer 6, the PET film 8, and the adhesive film 9 described in the above embodiment can identify the content of the display image when it is placed on the touch panel. A thing of the state.

  Moreover, in the said embodiment, although the projection capacitive touch panel was demonstrated to the example, the film for touchscreens which concerns on this invention is not restricted to this, The change of the weak electric current by contact of a pen point is caught, and a position is detected. Any capacitive touch panel that performs detection can be applied.

  The present invention will be further described based on examples. In the present example, the following experiments 1 to 6 were performed to identify the constituent requirements of the present invention and to confirm the effectiveness thereof.

[Experiment 1]
In Experiment 1, the fifth-generation Ipod (registered trademark) touch made by Apple was used as the touch panel, a film was not pasted on the cover glass, and a conductive rubber having a volume resistivity of 2.5 Ω · cm was used as the indicator. The minimum contact area diameter of the indicator that can be touched by the touch panel was verified.
As a result, it was confirmed that the touch panel would react if the indicator had a minimum contact area diameter of 4 mm of conductive rubber as the indicator.

[Experiment 2]
In Experiment 2, using a 5th generation iPod touch made by Apple as a touch panel, a 50 μm thick PET film was pasted on the cover glass via a 10 μm thick adhesive layer (acrylic adhesive), It was verified whether or not the touch panel responded using the conductive rubber having a contact area diameter of 4 mm to which the fifth-generation ipod touch manufactured by Apple as determined in Experiment 1 reacts.
As a result, the touch panel did not react. This is presumably because the thickness of the dielectric is increased, the distance between the conductive rubber and the sensor electrode is increased, and the change in capacitance is reduced.

[Experiment 3]
In Experiment 3, a fifth-generation iPod touch manufactured by Apple Inc. was used as a touch panel, a high resistance film (without a protective layer) was pasted on the cover glass, and the range of surface resistivity with which the touch panel reacted was verified.
As the high resistance film, a transparent conductive thin film (ITO film) having a predetermined surface resistivity is formed on a PET film having a thickness of 50 μm, and an adhesive layer (acrylic film) having a thickness of 10 μm is formed under the PET film. What formed the adhesive) was used. Further, a conductive rubber having a contact area diameter of 4 mm was used as the indicator.
In Experiment 3, when the value of the surface resistivity of the transparent conductive thin film was changed and verified, if the surface resistivity of the transparent conductive thin film was within the range of 10 ⁵ to 10 ⁸ Ω / sq, the indicator It was confirmed that the reaction occurred even when the contact area diameter was 4 mm.
That is, by forming a transparent conductive thin film having a surface resistivity in the range of 10 ⁵ to 10 ⁸ Ω / sq on the PET film, an effect of expanding the pseudo contact area of the indicator made of conductive rubber is obtained. Thus, it was confirmed that a change in capacitance that the touch panel can react between the conductive rubber and the sensor electrode occurs.

[Experiment 4]
In Experiment 4, based on the result of Experiment 3, the surface resistivity of the transparent conductive thin film was within the range of 10 ⁵ to 10 ⁸ Ω / sq, and the predetermined value was applied on the transparent conductive thin film of the high resistance film used in Experiment 3 above. A high resistance film provided with a protective layer having a thickness was used to verify whether the touch panel would react.
A 5th generation iPod touch manufactured by Apple Inc. was used as the touch panel, and a conductive rubber having a contact area diameter of 4 mm was used as the indicator.
Moreover, the protective layer formed by brand name: Acier-PMMA (made by Nidec Co., Ltd.) was formed, and a plurality of conditions were set within a thickness dimension of 1 to 30 μm.
The results of Experiment 4 are shown in Table 1. In Table 1, ○ indicates that the reaction occurs, × indicates that the reaction does not occur, and Δ indicates that the reaction occurs depending on the place of contact.

表１の結果から、透明導電性薄膜の表面抵抗率が１０^５〜１０^７Ω／ｓｑの範囲内であって、保護層の厚さ寸法が３０μｍ未満であれば、保護層を設けても擬似的な面積拡大効果が得られ、タッチパネルが反応することを確認した。

From the results in Table 1, if the surface resistivity of the transparent conductive thin film is in the range of 10 ⁵ to 10 ⁷ Ω / sq and the thickness dimension of the protective layer is less than 30 μm, even if a protective layer is provided, It was confirmed that an effective area expansion effect was obtained and the touch panel reacted.

[Experiment 5]
In Experiment 5, an experiment for verifying the result of Experiment 4 was further performed.
In a high resistance film, if the transparent conductive thin film is covered with a protective layer, the measurement electrode cannot be brought into direct contact with the transparent conductive thin film, and the conductivity of the transparent conductive thin film can be accurately evaluated. Since it was not possible, the electrostatic capacitance change apparatus (LCR meter) was used and the change of the electrostatic capacitance between electrodes was measured.
As schematically shown in FIG. 7, a high-resistance film 5 with a protective layer of 95 mm × 55 mm is pasted on a 200 mm × 100 mm square aluminum electrode 41, and a diameter of 8 mm is formed thereon. A cylindrical brass electrode 42 was placed and the contact was stabilized with a load of 2N, and then the capacitance was measured.

The high resistance film 5 has the same configuration as that shown in FIG. 1 in the above embodiment. When schematically shown in FIG. 8 using the same reference numerals, the high resistance film 5 has a thickness below the PET film 8 having a thickness of 50 μm. A 10 μm pressure-sensitive adhesive layer 9 (acrylic pressure-sensitive adhesive), a transparent conductive thin film 7 is formed on the upper layer, and a protective layer 6 made of trade name: Acier-PMMA (manufactured by Nidec Co., Ltd.) is formed on the transparent conductive thin film 7. The formed one was used.
Moreover, in the LCR meter (Agilent U1731) 43 used for the measurement of the electrostatic capacitance between electrodes, the measurement frequency was 1 kHz.
As the measurement conditions, the surface resistivity of the transparent conductive thin film 7 used for the high resistance film 5 is three conditions of 10 ⁵ Ω / sq, 10 ⁶ Ω / sq, and 10 ⁷ Ω / sq in which the touch panel operated in the experiment 4 described above. It was. The thickness of the protective layer 6 was changed within the range of 1 μm to 30 μm.

FIG. 9 is a graph showing the results of Experiment 5. In the graph of FIG. 9, the horizontal axis represents the thickness dimension (μm) of the protective layer, and the vertical axis represents the capacitance (pF / mm ² ) of the entire high resistance film 20.
In the graph of FIG. 9, Δ indicates the result when the surface resistivity of the transparent conductive thin film 7 is 10 ⁵ Ω / sq, □ indicates the result when 10 ⁶ Ω / sq, and ○ indicates 10 ^7. The result in the case of Ω / sq is shown. In addition, the graph shows the results of capacitance when a film having no transparent conductive thin film and a protective layer as a reference for comparison, specifically, a PET film having a thickness of 50 μm and an adhesive layer having a thickness of 10 μm. Shown in.

As shown in the graph of FIG. 9, the larger the thickness dimension of the protective layer 6, the smaller the amount of change in capacitance between the electrodes. From this, it has been confirmed that the larger the thickness dimension of the protective layer 6 is, the more the effect of artificially expanding the contact area of the indicator decreases.
Further, the maximum value of the capacitance between the electrodes on which the touch panel operates is ^{5 when} the protective layer 6 having a thickness of 1 μm is applied and formed on the transparent conductive thin film 7 having a surface resistivity of 10 ⁵ Ω / sq. It was 96 pF / mm ² .
On the other hand, the minimum value of the capacitance between the electrodes on which the touch panel operates is 0. When the protective layer 6 having a thickness of 5 μm or more is applied and formed on the transparent conductive thin film 7 having a surface resistivity of 10 ⁷ Ω / sq. 52 pF / mm ² .
Therefore, the range of change in the electrostatic capacitance that can be operated by the touch panel confirmed in Experiment 5 was 0.52 to 5.96 pF / mm ² .
In addition, when the transparent conductive thin film 7 and the protective layer 6 are not provided on the film, the touch panel does not react as shown in Experiment 2, but the capacitance between the electrodes at that time is 0.47 pF / mm ² . In other words, the minimum value of the capacitance at which the touch panel operates was a little over this value.

When attention is paid to the change in capacitance in the protective layer 6, when the high resistance film 5 having the protective layer 6 is pasted on the touch panel 3, it is formed between the indicator (stylus pen, finger, etc.) and the sensor electrode. As schematically shown in FIG. 10, the electrostatic capacitance is the capacitance C ₁ between the sensor electrode (touch panel 3) and the transparent conductive thin film 7, the transparent conductive thin film 7, and the indicator. the combined capacitance of the capacitance C ₂ between (i.e. protective layer 6).
_Assuming that the _total capacity of the capacitances C ₁ and C ₂ is C _total , the _total capacity C _total can be expressed by the following equation (3).

(Equation 3)
C _total = C ₁ · C ₂ / (C ₁ + C ₂ ) (3)

Here, the result of the capacitance value obtained by Experiment 5 (a configuration not including the cover glass 4) is the _total capacitance _Ctotal . Next, in order to clarify C ₁ with respect to each surface resistivity, the protective layer 6 was not formed, and the capacitance C ₁ was measured. As a result, when the surface resistivity was 10 ⁵ Ω / sq, C ₁ = 26.72 pF / mm ² . At 10 ⁶ Ω / sq, C ₁ = 3.98 pF / mm ² . At 10 ⁷ Ω / sq, C ₁ = 1.00 pF / mm ² . The result on the basis of the equation (3), the electrostatic capacitance C ₂ between the transparent conductive thin film 7 in each of the resistivity and the _pointer, that is, determining the capacitance C ₂ in the protective layer 6, FIG. 11 Can be represented in the graph.
When the surface resistivity of the transparent conductive thin film 7 is 10 ⁵ Ω / sq to 10 ⁷ Ω / sq, if the protective layer is less than 30 μm as shown in Experiment 4, a pseudo area expansion effect can be obtained. The touch panel reacts. C _total of the reaction lower limit at that time is 0.52 pF / mm ² , and C _{2 at} this time similarly takes the lower limit value. The value of the capacitance C ₂ in each protective layer 6 is 0.53 pF / mm ² when the surface resistivity is 10 ⁵ Ω / sq, 0.60 pF / mm ² , 10 ⁷ when the surface resistivity is 10 ⁶ Ω / sq. When Ω / sq, it was 1.09 pF / mm ² .
Therefore, it was found that the change in the capacitance C2 in the protective layer 6 that enables the touch panel to operate is at least 0.53 pF / mm ² or more.

  From the results of the above-described examples, by attaching the film for a touch panel (high resistance film) according to the present invention to the touch panel, even an indicator with a thin tip diameter like the stylus pen according to the present invention is simulated. It was confirmed that the contact area can be expanded, the capacitance change can be increased, and the touch panel can be operated.

DESCRIPTION OF SYMBOLS 1 Touch panel apparatus 2 LCD unit 3 Touch panel 4 Cover glass 5 High resistance film (film for touch panels)
6 Protective layer 7 Transparent conductive thin film 8 PET film 9 Adhesive layer 10 Insulating film 11 Electrode pad (sensor electrode)
12 Electrode pads (sensor electrodes)
30 Stylus pen 31 Nib 32 Nib holder (conduction part)

Claims (4)

A capacitive touch panel film interposed between a capacitive touch panel in which a sensor electrode is disposed and a conductive indicator,
A transparent conductive thin film having a predetermined surface resistivity set in a range of 10 ^5.0 to 10 ^7.0 Ω / sq formed on the surface of the film;
Having at least a transparent protective layer laminated on the transparent conductive thin film,
When the indicator contacts the surface of the protective layer, the dielectric between the predetermined region including the contact position and the sensor electrode has a capacitance of 0.52 to 5.96 pF / mm ² per unit area. A film for a touch panel, characterized in that the change occurs. When the indicator comes into contact with the surface of the protective layer, an electrostatic capacitance of at least 0.53 pF / mm ² is provided between the predetermined region including the contact position of the indicator and the transparent conductive thin film in the protective layer. The touch panel film according to claim 1, wherein a change in capacity occurs.   The thickness of the said protective layer is less than 30 micrometers, The film for touchscreens described in Claim 1 or Claim 2 characterized by the above-mentioned.   The said protective layer contains a ultraviolet absorber, The film for touchscreens in any one of Claim 1 thru | or 3 characterized by the above-mentioned.

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