JP6300025B2 - Film fixing structure and film fixing method - Google Patents

Description

  The present invention relates to an electrode film fixing structure and fixing method used in a capacitance type switch device.

  As a switch device that detects a touch operation on an operation surface (switch unit), a capacitance type switch device that detects a touch operation based on a change in capacitance is known (see, for example, Patent Document 1). In this type of switch device, there is a panel having an operation surface on which the touch operation is performed by the user, and an electrode film that is attached to the back surface of the panel and on which an electrode portion for detecting the touch operation is formed. Provided. The touch operation is detected by detecting a change in capacitance formed between the finger of the user who performed the touch operation and the electrode unit.

  By the way, in the switch device (touch panel) which can illuminate the operation surface of the panel or can display an image superimposed on the operation surface, the operation surface is formed to transmit light, and the electrode film is transparent It is formed. Further, on the back side of the electrode film, a light emitting unit (LED, liquid crystal display, etc.) that emits illumination light or image light is provided on the operation surface. The light from the light emitting unit is transmitted through the electrode film and irradiated onto the operation surface, whereby the operation surface is illuminated or an image is displayed over the operation surface.

  In such a switch device, it is necessary to ensure transparency of the electrode film even after the electrode film is attached to the panel. Therefore, conventionally, the electrode film has been attached to the panel by OCA (Optically Clear Adhesive, transparent double-sided tape).

JP 2008-192336 A

  However, the structure in which the entire surface of the electrode film is attached to the panel by OCA has a problem that internal bubbles are likely to be generated in OCA. When the internal bubbles are generated, the detection sensitivity (switch sensitivity) of the touch operation is changed between the portion where the internal bubbles are generated and the other portions, and the yield is also deteriorated. Moreover, since OCA is expensive compared with a general-purpose double-sided tape, and a dedicated attaching facility is required, a large amount of cost is required.

  The present invention has been made in view of the above circumstances, and the electrode film can be easily and inexpensively attached to the panel while ensuring the transparency of the electrode film after being attached, and the detection sensitivity of the touch operation is high. It is an object of the present invention to provide a film fixing structure and a film fixing method capable of suppressing changes between parts.

In order to solve the above problems, the film fixing structure of the present invention includes a panel having an operation surface on the surface on which a touch operation is performed by a user,
A transparent electrode film that is attached to the back surface of the panel and has an electrode portion for detecting a touch operation on the operation surface by a change in capacitance at a position facing the operation surface;
The electrode film is fixed to the back surface of the panel by a general-purpose adhesive in a transparent unnecessary region in the electrode film where the electrode portion is not formed, and the electrode portion is formed in the electrode film. It is characterized in that no adhesive is present between the transparent required area as the area and the back surface of the panel.

Further, the film fixing method of the present invention is configured such that the touch operation on the operation surface is performed on the back surface of the panel having the operation surface on which the touch operation is performed by the user on the front surface by changing the capacitance. A method of fixing a transparent electrode film on which an electrode part for detection is formed,
The electrode film is fixed to the back surface of the panel by a general-purpose adhesive in a transparent unnecessary region that is a region where the electrode portion is not formed in the electrode film, and the electrode portion is formed in the electrode film. It is characterized in that no adhesive is present between the transparent required area and the back surface of the panel.

  According to the present invention, since the electrode film is fixed to the panel with a general-purpose adhesive, the electrode film can be attached to the panel easily and at a lower cost than when OCA is used. In addition, the general-purpose adhesive is placed in the transparent unnecessary area where the electrode part is not formed in the electrode film, and there is no adhesive in the transparent required area where the electrode part is formed. Can also ensure the transparency of the electrode film (necessity of transparency). In addition, adhesive is not provided in the transparency required area, and internal bubbles of the adhesive are not generated in the transparency required area, so that the detection sensitivity of touch operation is prevented from changing between parts. it can. In the present specification, the term “general-purpose adhesive” means that if the electrode sheet is used for the transparency required area of the electrode sheet, the transparency of the transparency required area cannot be ensured (becomes opaque or decreases in transparency). , Refers to an adhesive other than OCA (opaque adhesive, low transparency adhesive).

It is sectional drawing of an electrostatic capacitance type switch apparatus. It is a top view of an electrode film. It is an enlarged view of the A section of FIG. It is sectional drawing of the overlay which concerns on the modification 1, and an electrode film. It is sectional drawing of the switch apparatus which concerns on the modification 2. It is sectional drawing of the switch apparatus of a comparative example. It is an enlarged view of the B section of FIG.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a cross-sectional view of the capacitance type switch device of the present embodiment. The switch device 1 in FIG. 1 is applied to, for example, an air conditioner panel that is provided in a vehicle and operates an air conditioner of the vehicle. First, the configuration of the switch device 1 will be described. The switch device 1 includes an overlay 2 (also referred to as an escutcheon) as a panel constituting the design surface of the switch device 1. The overlay 2 is made of resin and has a flat plate shape. A plurality of switch portions 24 (three switch portions in FIG. 1) are formed on the surface 21 of the overlay 2 as an operation surface on which a user performs a touch operation. Each switch unit 24 is assigned with each function (for example, a power on / off function, a function to adjust the air volume of conditioned air, a function to set temperature, etc.) of an operation target device (for example, an air conditioner). A design showing the assigned function is formed on the surface of each switch section 24.

  The overlay 2 is formed of a resin that does not transmit light (an opaque resin such as polycarbonate) other than the switch unit 24, while the switch unit 24 is formed so that it can be illuminated from the back side, that is, formed to transmit light. Has been. Specifically, the switch portion 24 of the overlay 2 is stamped into the design shape of the switch portion 24, or the switch portion 24 is made of a transparent resin (a resin that transmits light such as polyethylene terephthalate or acrylic resin). The switch part 24 that can be illuminated is formed by molding the transparent resin (switch part 24) and the other part (opaque resin) in two colors.

  An electrode film 3 is disposed on the back side of the overlay 2. FIG. 2 illustrates a plan view of the electrode film 3. In addition, in FIG. 2, the general purpose double-sided tape 4 mentioned later is also shown in figure. The electrode film 3 is a flexible transparent in which a plurality of electrode portions 31, a ground wire 32, and a plurality of wirings 33 are formed on a base film formed of an insulating transparent material (polyethylene terephthalate, acrylic resin, etc.). It is a film.

  The number of electrode portions 31 is the same as the number of switch portions 24 (three in FIG. 1 and FIG. 2). Each electrode part 31 is disposed at a position facing each switch part 24. The ground line 32 is formed so as to surround the outer periphery of each electrode portion 31. A wiring 33 is integrally formed on the peripheral edge of each electrode portion 31 and each ground line 32. The electrode part 31, the ground line 32, and the wiring 33 are formed of a conductive material, specifically, screen printing using a conductive polymer, silver paste, carbon, or the like. In particular, the electrode portion 31 is formed of a transparent electrode material (conductive polymer material: PEDOT (Pedot) or the like) so as to be transparent (light transmissive). Each electrode portion 31 is formed in the same size and shape as the switch portion 24.

  The plurality of wirings 33 are each formed in a long and narrow line, and are collected at one place at a predetermined interval. Each wiring 33 is bent and formed in, for example, a substantially L-shaped plane according to the position of the electrode part 31 to be connected, the terminal part is exposed from the electrode film 3, and determines whether or not there is a touch operation on the switch part 24. It is connected to a connector (not shown).

  The electrode film 3 is attached to the back surface 22 of the overlay 2. Specifically, as shown in FIG. 3, which is an enlarged view of a portion A in FIG. 1, a groove 23 is formed on the back surface 22 of the overlay 2. The groove 23 is formed in a portion of the back surface 22 facing the outer peripheral portion of the electrode film 3. A general-purpose double-sided tape 4 as a general-purpose adhesive is attached to the groove 23, one adhesive surface sticks to the bottom surface of the groove 23, and the other adhesive surface is one surface 3 a of the electrode film 3 (a surface facing the overlay 2). It is arrange | positioned in the form which sticks to the outer peripheral part. That is, the electrode film 3 is fixed to the back surface of the overlay 2 by the general-purpose double-sided tape 4 at the outer peripheral portion thereof. In the present embodiment, the electrode film 3 has a rectangular shape in plan view (see FIG. 2), but may have a shape other than the rectangular shape.

  The general-purpose double-sided tape 4 is a double-sided tape that does not belong to the OCA, and is an opaque or low-transparency double-sided tape that is used in various applications sold by home sensors and the like. The general-purpose double-sided tape 4 is configured to include, for example, a base material and adhesive layers on both sides thereof. A baseless double-sided tape may be adopted as the general-purpose double-sided tape 4. The thickness d2 (see FIG. 3) of the general-purpose double-sided tape 4 is, for example, about 0.01 mm.

  The groove 23 is formed at the same depth as the thickness d2 (for example, 0.1 mm) of the general-purpose double-sided tape 4 or a depth d1 shallower than the thickness d2. More specifically, the depth d1 of the groove 23 is such that the thickness d3 of the air layer 5 between the overlay 2 and the electrode film 3 is a thickness equivalent to OCA (for example, about 0.03 mm to 0.04 mm) or less. Is set to be When the depth d1 of the groove 23 is the same as the thickness d2 of the general-purpose double-sided tape 4, the thickness d3 of the air layer 5 becomes zero and the overlay 2 and the electrode film 3 are in direct contact with each other. Therefore, the touch operation on the switch unit 24 can be detected with high sensitivity. On the other hand, when the depth d1 of the groove 23 is shallower than the thickness d2 of the general-purpose double-sided tape 4, the adhesive surface of the general-purpose double-sided tape 4 can be surely exposed from the groove 23, and the electrode film 3 can be securely attached. It can be attached to the back surface 22 of the overlay 2.

  The general-purpose double-sided tape 4 is disposed in an area (transparency unnecessary area) other than the area (transparency required area) where the electrode part 31 that needs to transmit light from the LED 6 described later is formed in the electrode film 3. . Note that an adhesive (general-purpose double-sided tape, OCA) is not provided in the region where the electrode part 31 is formed. Specifically, as shown in FIG. 2, the general-purpose double-sided tape 4 is disposed over all sides 34 to 37 (entire circumference) of the outer peripheral portion of the electrode film 3 having a rectangular shape in plan view, that is, the electrode portion 31 is provided. It arrange | positions so that the area | region formed may be surrounded. In addition, the groove | channel 23 is formed along the outer peripheral part (all the sides 34-37) of the electrode part 31. FIG. In order to make the thickness of the air layer 5 constant, the groove 23 is formed at the same depth in any part.

  Thus, the electrode film 3 can be firmly fixed by arrange | positioning the general purpose double-sided tape 4 to all the sides 34-37. On the other hand, if the air layer 5 is sealed by disposing the general-purpose double-sided tape 4 over the entire circumference of the electrode film 3, the detection sensitivity of the touch operation changes when the air in the air layer 5 expands. There is a risk that. Therefore, as shown in FIG. 2, the general-purpose double-sided tape 4 is arranged over the entire circumference of the electrode film 3 in a form in which a cut 7 is provided in a part of the circumferential direction. As a result, the air layer 5 and the outside are connected to each other through the cut 7, and the cut 7 functions as an escape hole for letting the air in the air layer 5 (see FIG. 3) to the outside. Therefore, it can suppress that the thickness of the air layer 5 changes, and can suppress that a detection sensitivity changes.

  The escape hole of the air layer 5 may be formed in a portion other than the general-purpose double-sided tape 4, specifically, for example, in the electrode film 3. In this case, what is necessary is just to form the through-hole which penetrates between both surfaces in parts other than the electrode part 31 of the electrode film 3 as a relief hole.

  Further, the general-purpose double-sided tape 4 has only a part of the outer periphery of the electrode film 3 (for example, only two sides 34 and 35 on the long side in FIG. 2 or two sides 34 and 35 on the long side and a short side) It may be arranged on only one side 36). In this case, since the air layer 5 is inevitably connected to the outside, it is possible to suppress the thickness of the air layer 5 from being changed due to the expansion of air.

  Further, the general-purpose double-sided tape 4 may be disposed in a portion other than the outer peripheral portion as long as it is a region (transparency unnecessary region) other than the region where the electrode portion 31 is formed (transparency required region). Specifically, for example, the general-purpose double-sided tape 4 may be disposed near the center of the electrode film 3 in addition to the outer peripheral portion of the electrode film 3. Thereby, it is possible to suppress the vicinity of the center of the electrode film 3 from being bent by its own weight, and it is possible to suppress the thickness of the air layer 5 from being changed between parts. That is, it can suppress that detection sensitivity changes between parts.

  Returning to the description of FIG. 1, the switch device 1 includes the LED 6 for illumination of the switch unit 24. The LEDs 6 are provided as many as the number of the switch sections 24 (three in FIG. 1). Each LED 6 is arranged to emit light toward the electrode part 31 (switch part 24) at a position facing the electrode part 31 on the back surface side of the electrode film 3 (also a position facing the switch part 24). . LED6 is equivalent to the light emission part of this invention.

  Next, the function and effect of the switch device 1 will be described. The light emitted from the LED 6 is emitted from the switch unit 24 via the transparent electrode unit 31 and the air layer 5. Thereby, the switch part 24 can be illuminated. When a touch operation is performed on the switch unit 24, an electrical signal corresponding to an increase in capacitance formed between the user's finger and the electrode unit 31 disposed to face the user's finger is generated at the electrode unit 31. To do. Then, the electrical signal is sent to the control circuit (not shown) via the wiring 33 connected to the electrode unit 31, so that the control circuit determines that the switch unit 24 is touch-operated, and the touch-operated switch The function assigned to the unit 24 is executed.

  Moreover, since the electrode film 3 is fixed by the general-purpose double-sided tape 4 which is lower in cost than the OCA, the part cost can be reduced. Further, since the general-purpose double-sided tape 4 is attached to only a part of the electrode film 3 and not to the entire surface, a dedicated attaching facility for attaching the general-purpose double-sided tape 4 is not necessary, and manual operation by an assembly person is also possible. The electrode film 3 can be attached to the overlay 2. The initial cost can be reduced by eliminating the need for dedicated pasting equipment. Moreover, the electrode film 3 can be affixed to the overlay 2 more easily than when OCA is used, and the workability at the time of affixing can be improved.

  Moreover, since the general-purpose double-sided tape 4 is disposed in the groove 23, the thickness of the air layer 5 can be reduced. Thereby, even if it uses the general purpose double-sided tape 4 thicker than OCA, it can prevent that detection sensitivity deteriorates. Further, by managing the depth of the groove 23, the air layer 5 can secure a certain thickness, and it is possible to suppress the detection sensitivity from changing between the plurality of switch parts 24 or within the same switch part 24. .

  Further, since no substance (adhesive or the like) other than the air layer 5 is provided between the electrode part 31 and the overlay 2, the transparency of the electrode film 3 (transparency required area) after the electrode film 3 is attached. Can be secured. Therefore, the illumination of the switch unit 24 can be realized. In addition, since the internal bubbles of the adhesive are not generated in the transparent required area, it is possible to suppress the change in detection sensitivity between the plurality of switch parts 24 or within the same switch part 24 (reaction sensitivity is reduced). Can be kept constant). Further, the yield can be improved and the number of man-hours for management can be reduced as compared with the case where OCA is used.

  6 and 7 show the structure of a switch device in which an electrode film is attached by OCA as a comparative example of the present invention. In detail, FIG. 6 shows the switch device 100 of the comparative example. FIG. 7 shows an enlarged view of a portion B in FIG. As shown in FIG. 6, in the switch device 100, the electrode film 102 is disposed on the back surface side of the overlay 101 as in the switch device 1 of FIG. 1. The entire surface of the electrode film 102 is attached to the back surface of the overlay 101 by the OCA 103. Therefore, internal bubbles are likely to be generated in the OCA 103, and as shown in FIG. 7, even in the same switch unit 104, the portion 104a where the bubbles are generated is less likely to react than the other portion 104b. In addition, the comparative example is higher in cost and yield than the present invention.

(Modification 1)
Hereinafter, modifications of the present invention will be described. FIG. 4 shows a cross-sectional view of the overlay 11 and the electrode film 16 according to the first modification. As shown in FIG. 4, the overlay 11 is formed in a convexly curved shape (convex curved surface shape) as viewed from the operator side. The overlay may have a concavely curved shape (concave curved surface shape) when viewed from the operator side. A switch portion 12 is formed on the surface of the overlay 11. On the back surface of the overlay 11, a transparent flexible electrode film 16 having an electrode portion 17 formed at a position facing the switch portion 12 is disposed. The electrode film 16 is fixed to the back surface of the overlay 11 with a general-purpose double-sided tape 18 at the outer periphery of the electrode film 16 as in the above embodiment. A groove 13 is formed in a portion of the back surface of the overlay 11 where the general-purpose double-sided tape 18 is disposed.

  A convex portion 14 (rib) is partially formed on the back surface of the overlay 11. The convex part 14 is formed in the part which is not facing the electrode part 17 among the back surfaces of the overlay 11, for example. The protruding length of the convex portion 14 is set so that the thickness of the air layer 15 between the overlay 11 and the electrode film 16 is constant. Specifically, the protruding length of the convex portion 14 is set to a value corresponding to the difference between the thickness of the general-purpose double-sided tape 18 and the depth of the groove 13.

  According to this, even if the flexible electrode film 16 is curved following the curved surface overlay 11, the convex portion 14 prevents the vicinity of the center of the electrode film 16 from contacting the back surface of the overlay 11. Can be avoided. Therefore, the thickness of the air layer 15 can be kept constant, and the detection sensitivity can be prevented from changing between the parts. In addition, it is preferable that the convex part 14 is formed in the part which the electrode film 16 and the back surface of the overlay 11 may contact among the back surfaces of the overlay 11.

(Modification 2)
FIG. 5 shows a cross-sectional view of the switch device according to the second modification. The switch device of FIG. 5 is the same as the structure of FIG. In the structure of FIG. 5, embosses 54 (small irregularities) are formed on the back surface 51 a of the overlay 51. The texture 54 is formed, for example, in a portion facing the electrode portion 53 (an area through which light passes), and is not formed in any other area. On the other hand, the surface 52a of the electrode film 52 is a flat surface (mirror surface).

  Thereby, even if the back surface 51a of the overlay 51 and the surface 52a of the electrode film 52 come into contact with each other, it is possible to suppress the occurrence of moire on the design surface (switch portion 55). On the other hand, if the texture 54 is not formed, moire may occur on the design surface of the overlay 51 when the back surface (mirror surface) of the overlay 51 and the surface (mirror surface) of the electrode film 52 come into contact with each other. There is. The wrinkles may be formed on the entire back surface of the overlay 51, or may be formed on the surface 52a of the electrode film 52 (only the surface of the electrode portion 53 or the entire surface of the electrode film 52).

  In addition, this invention is not necessarily limited to the said embodiment, A various change is possible in the limit which does not deviate from description of a claim. For example, in the above-described embodiment, the example in which the present invention is applied to the configuration for illuminating the switch unit has been described. However, the configuration (with a touch sensor) that displays an image (liquid crystal image or the like) on the overlay surface (operation surface) is displayed. The present invention may be applied to a liquid crystal display or the like. In this case, the overlay is formed of, for example, a transparent resin (glass or the like), and a display device (liquid crystal display or the like) as a light emitting unit that emits image light toward the overlay is disposed on the back side of the electrode film. The electrode film is fixed to the back surface of the overlay with a general-purpose adhesive in a region where image light is not transmitted (transparent unnecessary region), and no adhesive is present in a region where image light is transmitted (transparency required region). Also by this, the same effect as the above embodiment can be obtained.

2, 11, 51 Overlay (panel)
24, 12, 55 Switch (operation surface)
3, 16, 52 Electrode film 31, 17, 53 Electrode part 4, 18 General-purpose double-sided tape (general-purpose adhesive)

Claims (6)

A panel (2, 11, 51) having an operation surface (24, 12, 55) on which a user performs a touch operation on the surface (21);
Electrode portions (31, 17, 53) for detecting a touch operation on the operation surface based on a change in capacitance were formed on the back surface (22) of the panel and opposed to the operation surface. A transparent electrode film (3, 16, 52),
The electrode film is fixed to a back surface of the panel by a general-purpose adhesive (4, 18) in a transparency unnecessary region, which is a region where the electrode part is not formed, in the electrode film, and the electrode of the electrode film during the back parts and is formed regions at which the transparency necessary area wherein the panels Ri adhesive absence der,
In the back surface of the panel, a groove (23, 13) having the same depth as the thickness of the general-purpose adhesive or shallower than the thickness is formed in a portion where the general-purpose adhesive is disposed. Fixed structure. On the back side of the electrode film, a light emitting unit (6) that emits light toward the operation surface is disposed,
The film fixing structure according to claim 1, wherein the operation surface is formed to transmit light. All sides (34, 35, 36, 37) of the outer periphery of the electrode film are fixed to the back surface of the panel by the general-purpose adhesive,
The film fixing structure according to claim 1 or 2 , wherein a hole (7) for connecting the air layer (5) surrounded by the general-purpose adhesive and the outside is formed. The panel (11) has a curved shape,
The back surface of the panel, wherein, wherein a convex portion protruding length to a thickness of a constant air layer (15) is set between the electrode film and the panel (14) is formed Item 4. The film fixing structure according to any one of Items 1 to 3 . 5. A texture (54) is formed on at least one of the back surface (51a) of the panel (51) and the surface (52a) of the electrode film facing the back surface . The film fixing structure according to Item 1 . The operation surface at a position facing the operation surface on the back surface (22) of the panel (2, 11, 51) having an operation surface (24, 12, 55) on which the user performs a touch operation on the front surface (21). A method of fixing a transparent electrode film (3, 16, 52) on which an electrode part (31, 17, 53) for detecting a touch operation on the sensor by a change in capacitance is formed,
The electrode film is fixed to the back surface of the panel with a general-purpose adhesive (4, 18) in a transparent unnecessary region, which is a region where the electrode portion is not formed in the electrode film, and the electrode portion of the electrode film The adhesive is not present between the transparent required region, which is a region where the is formed, and the back surface of the panel ,
In the back surface of the panel, a groove (23, 13) having the same depth as the thickness of the general-purpose adhesive or shallower than the thickness is formed in a portion where the general-purpose adhesive is disposed. Fixing method.

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