JP2016045841A - Input device and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an input device including a base material and a sensor film which are bonded to each other with an OCA layer interposed therebetween and are bent, and capable of maintaining high optical characteristics of a bent part despite such a configuration, and to provide a manufacturing method of the input device.SOLUTION: A manufacturing method includes a step of holding between a lower die 21 and an upper die 25 a laminate 10 obtained by bonding a base material and a sensor film with an OCA layer interposed therebetween, and bending the laminate 10 while being heated. In this step, the OCA layer is softened and then cooled, and the base material and the sensor film are brought into close contact with each other so that the OCA layer fills irregularities on the surfaces of the base material and the sensor film. This improves the optical characteristics.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an input device that is installed in a portable device or a vehicle-mounted device and generates an input signal based on a change in capacitance, and a method for manufacturing the same.

  An input device having a translucent shape and a curved shape has been developed for use in portable devices and in-vehicle devices. Patent Document 1 and Patent Document 2 describe a structure of a curved input device and a manufacturing method thereof.

  The input device described in Patent Document 1 includes a liquid crystal panel formed in a curved shape and a capacitive touch panel formed of a resin film. An adhesive layer is formed on the surface of the liquid crystal panel that is curved in advance, and the touch panel is adhesively fixed to the surface of the liquid crystal panel via the adhesive layer.

  In the input device described in Patent Document 2, the transparent conductive film layer and the decorative print layer are fixed to the concave surface of the glass substrate formed in a three-dimensional shape. In the manufacturing method, a transfer sheet in which a transparent conductive layer and a decorative printing layer are formed on a substrate having releasability is used. With the transparent conductive layer and the decorative print layer facing the surface of the glass substrate, press the transfer sheet against the surface using an elastic pad or elastic roll, and then pull only the substrate. Peel off and fix the transparent conductive layer and the decorative print layer to the surface of the glass substrate.

JP 2013-143079 A JP 2012-133428 A

  As described in Patent Document 1, a flexible touch panel is stacked on the surface of a base material such as a liquid crystal panel that is previously curved and bonded via an adhesive layer. It is difficult to securely bond the entire surface with an adhesive layer, and avoid forming minute gaps between the base material and the adhesive layer and between the touch panel and the adhesive layer in curved parts, etc. I can't.

  In addition, since fine irregularities are formed on the surface of the base material and the surface of the touch panel depending on the conditions in the manufacturing process, when the base material and the touch panel are bonded with an adhesive layer sandwiched, the fine irregularities and adhesion Fine voids are easily formed between the agent layer.

  When the gap or the gap is formed at a portion in contact with the adhesive, optical characteristics such as total light transmittance and haze are likely to be deteriorated.

  As described in Patent Document 2, even in the method of transferring the transparent conductive layer and the decorative print layer to the glass substrate, a fine gap is formed between the transparent conductive layer and the glass substrate, Phenomenon in which optical properties such as light transmittance and haze are deteriorated easily occurs. Further, since the transparent conductive layer is forcibly pressed against the glass substrate using an elastic pad or an elastic roll, the transparent conductive layer is easily damaged.

  The present invention solves the above-described conventional problems, and provides an input device capable of improving the adhesion between a base material and a sensor film in a curved portion and improving optical characteristics, and a method for manufacturing the same. The purpose is that.

According to a first aspect of the present invention, there is provided an input device in which a base material formed of a light-transmitting synthetic resin and a sensor film in which a light-transmitting electrode is formed on a light-transmitting resin film are joined.
The base material and the sensor film are joined via a transparent adhesive layer, a curved portion is formed in the base material and the sensor film, and the transparent adhesive layer is formed on the surface of the base material. It is filled with unevenness and unevenness of the surface of the sensor film.

  In the input device of the present invention, the unevenness is filled in the state where the transparent adhesive layer is cooled after being heated and softened.

  In the input device of the present invention, the base material and the sensor film are curved with a curvature in one direction.

  In the input device of the present invention, it is preferable that a flexible substrate is sandwiched between the base material and the sensor film, and the thickness of the transparent adhesive layer is equal to or greater than the thickness of the flexible substrate.

According to a second aspect of the present invention, there is provided an input device manufacturing method in which a base material formed of a light-transmitting synthetic resin and a sensor film having a light-transmitting electrode formed on a light-transmitting resin film are joined. ,
(1) a step of joining the base material and the sensor film via a transparent adhesive layer to form a laminate;
(2) Using a lower mold having a molding recess, placing the laminated body on the lower mold with the surface of the base material facing the molding depression, and heating the laminated body with an upper mold pressing projection Pressing and bending the laminate in the molding recess,
(3) The step of releasing the pressing by the pressing convex portion after cooling the laminated body, and taking out the input device composed of the laminated body having a curved portion from the lower mold,
It is characterized by having.

  In the method for manufacturing an input device of the present invention, in the step (2), it is preferable that the laminated body is installed after the lower mold and the upper mold are heated. Moreover, in the step (2), it is preferable to place the laminated body heated in advance on the lower mold.

  In the method for manufacturing an input device of the present invention, in the step (1), the surface of the sensor film is covered with a protective film, and in the step (2), the protective film appears on the pressing convex portion. It is preferable to press.

  In the method for manufacturing an input device of the present invention, in the step (2), when the laminate is pressed by the pressing projection, a gap is formed between the curved laminate and the surface of the molding recess. Is preferably formed.

  Furthermore, in the manufacturing method of the input device of the present invention, in the step (1), a flexible substrate is sandwiched between the base material and the sensor film, and the thickness of the transparent adhesive layer is determined by the flexible substrate. It is preferable to set the thickness to be equal to or greater than the thickness.

  In the input device of the present invention, the transparent adhesive layer interposed between the substrate and the sensor film is in a state of being in close contact with the surface irregularities of the substrate and the surface irregularities of the sensor film, It can prevent that optical characteristics, such as a total light transmittance and a haze, deteriorate in a curved part.

  In the manufacturing method of the input device according to the present invention, the laminated body in which the base material and the sensor film are stacked via the transparent adhesive layer is bent while being heated and cooled in the bent state. Taken from. The transparent adhesive layer interposed between the base material and the sensor film is cooled after being heated and softened, and at the time of bending, the transparent adhesive layer is formed on the base material in the curved portion. And pressure is applied to the surface of the sensor film. As a result, the transparent adhesive layer is filled into the irregularities on the surface of the substrate and the irregularities on the surface of the sensor film, and the transparent adhesive layer is in close contact with the substrate and the sensor film. As a result, deterioration of optical characteristics can be prevented.

  In addition, when the laminate is pressed by the pressing convex portion, if a gap is formed between the curved laminate and the surface of the molding recess, the surface of the base material is not pressed against the surface of the molding recess. The surface of the base material can be prevented from being damaged.

The perspective view which shows the input device of embodiment of this invention, (A) is a plan view of the laminate in the manufacturing process of the input device, (B) is a cross-sectional view of (A) cut along line BB, FIG. 2B is an enlarged cross-sectional view enlarging a part of FIG. Sectional drawing which shows a metal mold | die and a laminated body, Sectional drawing which shows the process which curved the laminated body using the metal mold | die, A micrograph showing an enlarged view of the joint between the substrate and the sensor film in the curved portion of the completed input device, The flowchart which shows the process of the manufacturing method of an input device,

<Basic structure of input device>
An input device 1 according to an embodiment of the present invention shown in FIG. 1 has a base material 2 formed of a light-transmitting synthetic resin material. The base material 2 has a curved portion that is curved so as to have a curvature only in one direction. In the embodiment, the substrate 2 has a three-dimensional shape that is curved in one direction as a whole. The base material 2 is formed of an acrylic resin, that is, a polymethyl methacrylate resin (PMMA resin).

  The substrate 2 has a convex surface 2a and a concave surface 2b. The sensor film 3 is bonded to the concave surface 2 b of the base material 2, and the surface 2 b and the sensor film 3 are bonded and fixed via an OCA layer (optically transparent adhesive layer) 4. The sensor film 3 has a sensor substrate formed of PET (polyethylene terephthalate) resin, which is a translucent synthetic resin film. On the surface 3a of the sensor film 3 facing the base material 2, a translucent electrode layer is formed on the surface of the sensor substrate.

  The translucent electrode layer is made of ITO (indium tin oxide). Alternatively, the electrode layer is formed of a conductive nanowire such as a silver nanowire, or a mesh-like metal layer such as a copper mesh or a gold mesh.

  A plurality of electrode layers are formed on the surface of the sensor substrate, and these electrode layers are divided into two groups, and a capacitance is formed between the electrode layer of one group and the electrode layer of the other group. ing. When a pulsed drive voltage is applied to one group of electrode layers, current flows through the other group of electrode layers at the rise and fall of the pulse. Since this current value changes according to the capacitance, when a person's finger approaches the convex surface 2a of the base material 2, the current value changes, so that the finger is placed at any position on the surface 2a. It is possible to detect the approach. Alternatively, a plurality of independent electrode layers are provided on the surface 2a, a driving voltage is applied to each electrode layer in order, and a current that flows between the electrode layer to which the driving voltage is applied and the electrode layer adjacent thereto is applied. It may be a method of detecting.

  A flexible substrate 5 is connected to the sensor film 3 as a wiring substrate, and a lead layer formed on the flexible substrate is electrically connected to each electrode layer. A plurality of land portions 5a are formed at the end of the flexible substrate 5, and each land portion 5a is continuous with the lead layer. When the input device 1 is installed in various electronic devices, the land portion 5a is connected to a circuit portion in the device.

  Since most of the input device 1 shown in FIG. 1 is translucent, the screen of a display panel such as a liquid crystal panel disposed therebelow can be viewed from the front of the convex surface 2a. An input operation can be performed by touching the convex surface 2a with a finger while referring to the screen.

<Laminated body and mold structure>
2A and 2B show a flat laminated body 10 before being formed into a curved shape. The laminate 10 has the translucent substrate 2. On the surface 2 b of the base material 2, a decorative layer 6 is provided in a peripheral region excluding the central portion. The decorative layer 6 is a printing layer of black, dark green, or metal color, and the frame region where the decorative layer 6 is formed is a portion that cannot transmit light. A central region where the decorative layer 6 is not formed is a light-transmitting region, and a screen of a display panel located thereunder is visible through this region.

  As shown also in FIG. 3, the flexible substrate 5 is bonded to the surface 3 a of the sensor film 3, and the lead layer formed on the flexible substrate 5 extends from a plurality of electrode layers formed on the surface 3 a of the sensor film 3. It is joined to the conductor pattern by soldering or the like in a one-to-one relationship. The flexible substrate 5 is joined to the sensor film 3 in the region where the decorative layer 6 is formed, so that the flexible substrate 5 cannot be seen from the front of the surface 2 a of the base material 2.

  The substrate 2 and the sensor film 3 are bonded via the OCA layer 4. The OCA layer 4 is a sheet-like adhesive layer. Alternatively, a liquid material is used and applied to the surface 2b of the substrate 2. As shown in an enlarged view in FIG. 3, the thickness dimension T0 of the OCA layer 4 is set to be equal to or slightly larger than the thickness dimension T1 of the flexible substrate 5. In FIG. 3, the flexible substrate 5 and the decorative layer 6 are overlapped between the base material 2 and the sensor film 3, but the decorative layer 6 is a printing layer and its thickness is almost ignored. Therefore, the distance between the base material 2 and the sensor film 3 substantially matches the thickness dimension T1 of the flexible substrate 5. Therefore, by setting the thickness dimension T0 of the OCA layer 4 to be equal to or greater than the thickness dimension T1, the OCA layer 4 softened by heating in the subsequent bending step is used as the base material 2. The surface 2b of the sensor and the surface 3a of the sensor film 3 are easily adhered to each other.

  As shown in FIGS. 2B and 3, in the laminate 10, the exposed surface 3 b of the sensor film 3 is covered with a protective film 7. The protective film 7 is formed of a resin film having releasability.

  In the actual manufacturing process, the decorative layer 6 is printed on a large-area PMMA plate, and then the PMMA plate is cut and separated to obtain individual substrates 2. And the sensor film 3 is adhere | attached on this base material 2 through the OCA layer 4, and the laminated body 10 is comprised.

  FIG. 4 shows a mold 20 for bending the laminate 10. The mold 20 includes a lower mold 21 and an upper mold 25.

  A molding recess 22 is formed in the lower mold 21. The molding recess 22 has a curvature directed in one direction, and its curvature radius is R1. At the opening end of the molding recess 22, holding recesses 23, 23 that support both end portions of the laminate 10 are formed. A pressing convex portion 26 is formed integrally with the upper mold 25. The curvature of the pressing convex portion 26 is directed in the same direction as the molding concave portion 22, and the radius of curvature of the pressing convex portion 26 is R2. The curvature radius R2 is formed smaller than the curvature radius R1. The upper mold 25 is integrally formed with support portions 27, 27 extending on both sides of the pressing convex portion 26. An escape recess 28 is formed on the lower surface of one support 27 to escape the flexible substrate 5.

<Manufacturing method of input device>
FIG. 7 describes the steps of the input device manufacturing method.

  In the process P1, the laminate 10 before molding is heated, and at the same time, the mold 20 is heated in the process P2. The heating temperature of the laminated body 10 is set to a temperature at which the OCA layer 4 is heated and softened, but does not flow out between the substrate 2 and the sensor film 3. The preferable heating temperature of the laminated body 10 is about 95 to 105 ° C. The temperature of the mold 20 is set slightly higher than the heating temperature of the laminate 10, and is preferably set about 5 to 15 ° C. higher than the heating temperature of the laminate 10.

  The laminated body 10 is installed in the lower mold | type 21 by process P3 shown in FIG. As shown in FIG. 4, the laminate 10 is installed in the lower mold 21 so that the surface 2 a of the base material 2 faces the molding recess 22. In step P4, both end portions of the laminate 10 are supported in the holding recesses 23, 23 of the lower mold 21.

  In step P <b> 5, the upper mold 25 is lowered toward the lower mold 21 while the laminated body 10 is held on the lower mold 21. As shown in FIG. 5, the laminated body 10 is bent in the molding concave portion 22 by pressing the protective film 7 side with the pressing convex portion 26 of the upper mold 25.

  When the laminated body 10 is heated to about 95 to 105 ° C., a part of the structure of the OCA layer 4 is in a molten state and the adhesive layer is softened. When the laminated body 10 is pressed and bent by the pressing convex portion 26 in this state, the base material 2 and the sensor film 3 try to approach each other, so the softened OCA layer 4 is compressed in the thickness direction and the internal pressure is reduced. To rise. Due to this increase in pressure, the softened OCA layer is pressed against the surface 2 b of the substrate 2 and the surface 3 a of the sensor film 3. The surface 2b of the substrate 2 made of PMMA has irregularities with a center line average roughness Ra of about 8 to 13 μm. The surface 3a of the sensor film 3 and the surface of the electrode layer made of ITO formed on the surface 3a also have irregularities with a center line average roughness Ra of about 5 to 100 nm. The softened OCA layer under pressure is filled in the unevenness of the surface 2b of the substrate 2 and the unevenness of the surface 3a of the sensor film 3, and comes into close contact with the surfaces 2b and 3a.

  As shown in FIG. 5, the maximum distance by which the upper mold 25 is lowered with respect to the lower mold 21 is a gap between the curved surface 2 a of the base material 2 of the laminate 10 and the inner surface of the molding recess 22. It is set to such an extent that δ is maintained. As shown in FIG. 2 (A), when the longitudinal dimension L of the laminate 10 before curve molding is about 55 to 77 mm, the downward apex of the laminate 10 being bent, and the molding recess 22 It is preferable that the maximum value of the gap δ with the inner surface be maintained at about 0.5 to 1.5 mm.

  When the gap δ is formed, the base material 2 is not pressed against the molding recess 22 in the state of FIG. 5, so that a force for partially compressing the laminated body 10 in the thickness direction does not act. The extreme concentration of stress acting on 10 can be prevented. Since bending stress acts on almost the entire area of the laminated body 10, a relatively uniform pressure acts on the OCA layer 4 between the base material 2 and the sensor film 3. The surface 2b of the sensor and the surface 3a of the sensor film 3 can be in close contact with each other by being uniformly pressurized.

  In addition, by forming the gap δ, it is possible to reduce the places where the surface 2a of the substrate 2 of the laminate 10 is in contact with the lower side 21 and prevent the surface 2a from being damaged.

  In the process P6 shown in FIG. 7, as shown in FIG. 5, the mold clamping state is maintained for a predetermined time while the upper mold 25 is pressed against the lower mold 21. In this step, the bending state of the laminate 10 is stabilized, the OCA layer 4 is spread uniformly between the substrate 2 and the sensor film 3, and the OCA layer 4 is formed on the surface 2b of the substrate 2 and the sensor film 3. It comes in close contact with the surface 3a.

  In step P7, the mold 20 is cooled in a clamped state, and when the temperature of the mold 20 is lowered to room temperature in step P8, the lower mold 21 and the upper mold 25 are opened. The body 10 is removed. When the protective film 7 is peeled off from the laminated body 10, the input device 1 shown in FIG. 1 is completed.

  The completed input device 1 shown in FIG. 1 has a concave radius of curvature R0 of the laminated body 10 of about 20 to 60 mm. The entire shape is a part of a cylinder, and the circumference in the curvature direction (dimension L shown in FIG. 2A) is about 1/3 to 1/2 of the circumference of the radius R0.

  Note that the present invention is not limited to the above-described embodiment, and only a part of the input device 1 may be curved, and the shape of the curved portion is a solid having a curvature in multiple directions rather than in one direction. It may be a shape.

  The input device 1 of the embodiment has a length dimension L shown in FIG. 2 of 65 mm and a width dimension orthogonal to the dimension L of 34 mm. The thickness of the base material 2 by PMMA is 1.0 mm, the thickness dimension of the sensor film 3 is 50 μm, the thickness dimension of the flexible substrate 5 is 75 μm, and the thickness dimension of the OCA layer 4 is 75 μm. The thickness of the protective film 7 was 125 μm.

  The laminated body 10 having the above configuration was heated to 100 ° C., the temperature of the lower mold 21 was 115 ° C., the temperature of the upper mold 25 was 105 ° C., and the time from the holding in the process P6 to the mold opening of P8 was 90 seconds. The completed input device 1 has a radius of curvature R0 shown in FIG. 1 of 40 mm.

  FIG. 6 is a photomicrograph showing a part of the input device 1 after completion. From this photograph, the OCA layer 4 is heated to be in a softened state, and is cooled while being pressed by receiving bending stress between the base material 2 and the sensor film 3, so that the OCA layer 4 is formed on the base material 2. The unevenness of the surface 2b and the unevenness of the surface 3a of the sensor film 3 are filled, and the OCA layer 4 and the substrate 2 and the OCA layer 4 and the sensor film 3 are in close contact with each other without having a fine gap (fine air layer). You can see that

  Example 1 and Example 2 shown in Table 1 below are the same as those described in the above example, and different samples were used.

  The total light transmittance, diffuse transmittance, and haze of Examples 1 and 2 were measured by “initial value”, and then left after being tested for 120 hours in an environment at a temperature of 85 ° C. and a relative humidity of 85% “after test”. Is displayed.

  The comparative example uses the same base material 2 and the sensor film 3 as in the example, only the base material 2 is curved in the same manner as in the example, and the sensor film 3 is bonded to the curved base material 2 via the OCA layer 4. We used what we did.

  The total light transmittance, diffuse transmittance, and haze of the comparative example were measured as “initial value” and then left as it was for 75 hours in an environment where the temperature was 85 ° C. and the relative humidity was 85%. ing.

  From Table 1, it can be seen that in Examples 1 and 2, the optical measurement does not deteriorate even after the test even though the standing time at high temperature and high humidity is longer than that of the comparative example. That is, the OCA layer 4 between the base material 2 and the sensor film 3 is filled in the unevenness of the surface of the base material 2 and the sensor film 3, and an air layer is formed between the base material 2 and the sensor film 3. Is no longer formed, and optical identification can be improved.

DESCRIPTION OF SYMBOLS 1 Input device 2 Base material 3 Sensor film 4 OCA layer 5 Flexible substrate 6 Decorating layer 7 Protective film 10 Laminate 20 Mold 21 Lower mold 22 Molding concave part 25 Upper mold 26 Pressing convex part

Claims (10)

In an input device in which a base material formed of a light-transmitting synthetic resin and a sensor film in which a light-transmitting electrode is formed on a light-transmitting resin film are joined,
The base material and the sensor film are joined via a transparent adhesive layer, and a curved portion is formed in the base material and the sensor film,
The input device, wherein the transparent adhesive layer is filled in irregularities on the surface of the substrate and irregularities on the surface of the sensor film.   The input device according to claim 1, wherein the transparent adhesive layer is filled in the unevenness in a state of being cooled after being heated and softened.   The input device according to claim 1, wherein the base material and the sensor film are curved with a curvature in one direction.   The flexible substrate is pinched | interposed between the said base material and the said sensor film, and the thickness of the said transparent adhesive bond layer is more than the thickness of the said flexible substrate. Input device. In the manufacturing method of an input device in which a base material formed of a light-transmitting synthetic resin and a sensor film in which a light-transmitting electrode is formed on a light-transmitting resin film are joined,
(1) a step of joining the base material and the sensor film via a transparent adhesive layer to form a laminate;
(2) Using a lower mold having a molding recess, placing the laminated body on the lower mold with the surface of the base material facing the molding depression, and heating the laminated body with an upper mold pressing projection Pressing and bending the laminate in the molding recess,
(3) The step of releasing the pressing by the pressing convex portion after cooling the laminated body, and taking out the input device composed of the laminated body having a curved portion from the lower mold,
A method for manufacturing an input device.   The method for manufacturing an input device according to claim 5, wherein, in the step (2), the stacked body is installed after the lower mold and the upper mold are heated.   The method for manufacturing an input device according to claim 6, wherein in the step (2), the laminated body heated in advance is placed on the lower mold.   The surface of the sensor film is covered with a protective film in the step (1), and the surface on which the protective film appears is pressed by the pressing convex portion in the step (2). A method for manufacturing the input device according to claim 1.   9. The method according to claim 5, wherein, in the step (2), a gap is formed between the curved laminate and the surface of the molding recess when the laminate is pressed by the pressing protrusion. The manufacturing method of the input device of description.   10. The step (1), wherein a flexible substrate is sandwiched between the base material and the sensor film, and the thickness of the transparent adhesive layer is set to be equal to or greater than the thickness of the flexible substrate. The manufacturing method of the input device in any one of.