JP2013225195A - Film-like electrostatic capacitance type touch panel and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To specify favorite relation between pitches of periodic light shield patterns that metal meshes and a matrix drive type display have when an electrostatic capacitance type touch panel having meshed metal wires laid on a film is mounted on the matrix drive type display.SOLUTION: There is provided a film-like electrostatic capacitance type touch panel used while placed over a display device having colored pixels laid periodically at a pitch (p) in two orthogonal directions, and the touch panel includes striped metal wires having a pitch P in one direction and striped metal wires having a pitch P in a direction orthogonal thereto, P being (3.5±0.1) times as large as (p).

Description

  The present invention relates to a capacitive touch panel used as coordinate input means, and more particularly to a technique for eliminating a moire pattern that occurs when a touch panel is overlaid on a matrix drive type display.

  2. Description of the Related Art In recent years, touch panel type input devices (hereinafter simply referred to as touch panels) have been adopted for operation units of various electronic devices such as mobile phones, portable information terminals, and car navigation systems. The touch panel is used as an input device that detects a contact position of a fingertip or a pen tip on a display surface of a display panel such as a liquid crystal display device or an organic EL device. There are various types of touch panels, such as a resistance film type and a capacitance type, depending on the structure and detection method.

  There are two types of capacitive touch panels: surface type and projection type. Both methods detect the position by capturing the change in capacitance between the fingertip and the conductive film. Since electrostatic coupling occurs only when the finger approaches the sensor surface, it is possible to display a cursor before contact. The object to be pressed needs to be a finger or an electrostatically conductive material equivalent to that of the finger, but the alternating current that flows in accordance with the change in the capacitance does not depend on the impedance of the contact medium.

  In particular, the projected capacitive method can detect multiple points of the fingertip. In general, the projection type has a configuration in which a support substrate on which an electrode layer and a control IC are mounted is covered with a protective insulating resin. Although the details of the electrode layer are omitted, on the support substrate such as glass or plastic, a large number of mosaic electrodes composed of one set of X and Y direction electrodes are formed on a support substrate such as glass or plastic using a transparent electrode material (ITO). Yes. The X direction electrode and the Y direction electrode are all laid while maintaining insulation (Patent Documents 1 and 2).

  Further, as shown in FIG. 1B, stripe-shaped metal wires 7 extending in the vertical direction and metal wires 6 extending in the horizontal direction may be laid on the substrate while maintaining insulation (Patent Documents 3 and 4). ). Metal wiring is more advantageous because it has lower sensitivity than ITO, but metal is light-shielding and reflective, so unlike ITO, wiring density and aperture ratio are problematic. Whether the ITO array or the metal array is touched or approached, the change in the capacitance of the nearby electrode can be known from one set of vertical and horizontal electrode rows, so that the contact position can be specified with a high degree of accuracy, apart from the resolution.

  Multiple points can be detected by a large number of electrode rows 6 and 7 running vertically and horizontally. However, since the number of terminals is large and the wiring using ITO is too high in resistance, it is not suitable for a large screen as it is. Therefore, in a large touch panel, in order to connect an FPC on which an IC for position detection is mounted with a sensor substrate, a wiring for taking out a wide line is provided around the substrate. However, it is necessary to use a metal wiring for these wirings. There is a tendency for costs to increase.

  Therefore, as a touch panel for a large display with a diagonal of 30 inches or more, the metal wiring type from the beginning has a lower resistance, and it can be manufactured at low cost by laying the metal wiring on the film. Can be said to be expensive. However, when a light-shielding metal wiring such as a copper thin wire is formed on a film as a sensor electrode, it cannot be seen with a transparent ITO electrode when it is stacked on a matrix drive type display such as a liquid crystal display or an organic EL display. There is a problem that moiré patterns are likely to occur.

Moire has an image display area with the pitch of copper or aluminum wiring with a line width of several tens of μm and the pitch of the periodic light-shielding pattern (light-shielding black matrix and semi-light-shielding colored pixel pattern) on the display side. This occurs when they do not match as a whole, or when they are not completely parallel but inclined. Moire leads to uneven color and blurring of the image, and directly leads to a decrease in the quality of the displayed image.

JP 2012-01462 A JP 2012-004042 A JP 2011-253263 A JP 2011-248722 A

  The present invention has been made in view of the above problems, and the period of the metal mesh and the display when the capacitive touch panel in which the mesh-like metal wiring is laid on the film is mounted on the matrix-driven display is provided. It was an object to specify a preferable relationship between pitches of typical light-shielding patterns.

  The invention according to claim 1 to achieve the above object is a film-like capacitive touch panel that is used in an overlapping manner with a display device including colored pixels periodically laid with a pitch p in two orthogonal directions. The touch panel includes a stripe-shaped metal wiring having a pitch P in one direction and a stripe-shaped metal wiring having a pitch P in a direction orthogonal thereto, where P is p (3.5 ± 0.1). The film-like capacitive touch panel is characterized by being doubled.

  The invention according to claim 2 is a film-like capacitive touch panel that is used by being superimposed on a display device including colored pixels periodically laid in two orthogonal directions at a pitch p. A stripe-shaped metal wiring having a pitch of P in one direction and a stripe-shaped metal wiring having a pitch of P in a direction orthogonal thereto, where P is (3.5 / √2 ± 0.1) times p. This is a film-like capacitive touch panel.

  The invention according to claim 3 is the capacitive touch panel according to claim 1 or 2, wherein the metal wiring has a line width of 50 μm or less.

  The invention according to claim 4 is characterized in that the repeating direction of the colored pixels of the display device and the direction in which the stripe-shaped metal wiring extends are the same, and the film-like capacitance according to claim 1 or 3 Type touch panel.

  The invention according to claim 5 is characterized in that the direction in which the colored pixels of the display device repeat and the direction in which the stripe-shaped metal wiring extends form an angle of 45 °. This is a method of using a capacitive touch panel.

When the touch panel according to the present invention is mounted on a display device having periodic coloring (coloring) pixels such as a liquid crystal display and an organic EL display, the moire pattern is provided. Has the effect of not being visually recognized.
If the range in which the moiré is not visually recognized can be determined in advance, it is not necessary to repeat the design trial manufacture of the touch panel to obtain the optimum pitch every time the specification is changed.
The difference between claim 1 and claim 2 is the difference in the direction in which the periodic light shielding patterns of the display device and the touch panel are combined, as described below.

  According to the third aspect of the present invention, there is an effect that the transmittance is high and moire is not easily recognized.

  In the fourth aspect of the present invention, when the relationship between the pitches is satisfied, moiré occurs when the display device and the touch panel are overlapped so that the direction of the metal wiring of the touch panel and the repetition direction of the colored pixels are parallel to each other. There is an effect that there are few.

  According to the fifth aspect of the present invention, when the relationship between the pitches is satisfied, moiré occurs when the display device and the touch panel are overlapped so that the metal wiring direction of the touch panel and the repeating direction of the colored pixels are 45 °. There is an effect that there is little.

(A) It is a figure explaining the example of arrangement | positioning of the coloring pixel of a color filter, and a black matrix, and is a figure which shows the definition of arrangement | positioning pitch p. (B) It is a figure explaining an example of the metal wiring of a touch panel, and is a figure which shows the definition of the pitch P of arrangement | positioning. It is a figure explaining how to overlap a touch panel and a display device. (A) When the repeating direction of the metal mesh and the colored pixel is parallel, (b) When the repeating direction of the metal mesh and the colored pixel forms 45 °. (A)-(d) It is a figure of the cross-sectional view explaining the way of the mesh structure of metal wiring. (A) Metal mesh on one side of the film, (b) Metal stripe on the front and back of the film, (c) Bonding, (d) Metal mesh on the front and back of the film.

  Hereinafter, embodiments of the touch panel according to the present invention will be described with reference to the drawings.

Moire is a striped pattern having a different period from any period generated by a shift in the period when a plurality of periodic patterns are superimposed. For example, when two sets of stripe patterns are diagonally overlapped, a stripe pattern in which the intersecting portion has a pitch different from the stripe pitch can be seen. Or, it occurs when two checkered patterns with different pitches are stacked.
A system in which a touch panel is mounted on a matrix-driven display device such as a liquid crystal display device or an organic EL device corresponds to a case where two stripe patterns are overlapped.

  First, a periodic pattern on the display device side will be described using a liquid crystal display as an example. A partial conceptual diagram of the color filter 1 used in the liquid crystal display is shown in FIG. This block is two-dimensionally laid out with colored pixels 2 of three colors of red (R), green (G), and blue (B) as one block. The gaps between the colored pixels 2 are embedded with a black matrix 3 for light shielding.

  The vertical / horizontal ratio of the individual colored pixels 2 is approximately 3: 1 and is substantially square with three colors. Therefore, the laying pitch of each colored pixel (the pitch between the red pixel and the red pixel, not the distance between the adjacent red pixel and the green pixel) is the horizontal direction including the width of the black matrix 3 and the vertical direction perpendicular thereto. All are the same, and the pitch of the black matrix 3 which divides a block is also the same. The width of the black matrix 3 can be set as appropriate, but the pitch itself does not change. The colored pixels have a repeating configuration of R, G, and B in the horizontal direction, but have a stripe configuration in which pixels of the same color are arranged in the vertical direction.

  In this specification, the repetitive pitch is represented by p. p is generally in the range of 100 to 1000 μm, depending on the size of the display and the number of pixels. The black matrix 3 is completely light-shielding, but the colored pixels 2 are light-transmissive. In FIG. 1A, the black matrix and the colored pixels are both partitioned by a straight line, but in some cases, there may be periodic unevenness.

  The organic EL display also has the same arrangement of pixels that emit light as the liquid crystal display. The portion that partitions the light emitting pixels is not called a black matrix, but a stripe-shaped partition wall is formed so that the light emitting material is not mixed, and this also has a light shielding property, so that moire may occur.

  A top view of the metal wiring of the touch panel 5 is shown in FIG. Two sets of metal wirings 6 and 7 (double lines and solid lines in the figure) arranged in stripes are prepared and arranged so as to be orthogonal to each other so as not to be short-circuited at the intersection. Since the metal wirings 6 and 7 have a light-shielding property, if the line width is increased, the aperture ratio is decreased and the transmittance is decreased. If the stripe pitch P is long, the resolution as the position sensor is decreased. Is done.

  When the touch panel 5 is the same phase and the same voltage AC is applied to both ends of a conductor such as a metal wiring, when an electrostatic and conductive medium such as a finger or hand is brought close to the conductor, This is an electronic device that utilizes the phenomenon that capacitive coupling occurs between a medium that is considered to be grounded and a conductor (which is also grounded), and an excessive alternating current flows through the conductor.

  Therefore, it is not necessary for the finger to touch the conductor directly, and the conductor may be contacted or approached via the dielectric. Since the conductor is soiled when the hand touches the conductor of the sensor unit, the conductor is usually used by being coated with an antifouling transparent resin. The conductors (hereinafter referred to as electrodes) do not necessarily exist on the same plane, and may be disposed between insulating resins or the like. However, since the substantial distance to the contact medium (for example, a finger) changes, there is a possibility that the sensitivity changes depending on whether the sensitivity is above or below the insulating resin.

  In principle, it is possible to detect which electrode material is close to which side by simply placing the electrode material appropriately, but in order to maintain accuracy as a position sensor, linear electrodes are arranged in an XY matrix. Thus, the position is calculated from the intersection by independently detecting which X-direction electrode and which Y-direction electrode, not where on which electrode. Of course, all the electrodes in the X direction and the Y direction need to be insulated. Moreover, the electrode does not necessarily need to be linear. In the case of a light-shielding metal wiring, fine lines that are difficult to see within the range allowed by the transmittance are arranged as tightly as possible.

  Therefore, when the liquid crystal display having the periodic light-shielding or semi-light-shielding pattern shown in FIG. 1A and the touch panel shown in FIG. 1B are overlapped to form a display with a touch panel, for example, black matrix 3 and metal A moire pattern may occur unless the wiring 7 is completely overlapped. For large displays, a film type touch panel is often stacked, and because it is a film, the pitch P cannot be processed in exactly the same way on the entire film surface. Periodic moire patterns are produced.

  Next, the laying form of the metal electrode of the film-like touch panel 5 will be described with reference to FIG. The first embodiment is a touch panel provided with a copper wiring in a mesh shape so that the aperture ratio is within a range of 90 to 98% on one side of a region where the film base 10 having a thickness of 50 to 100 μm needs to be seen through. 5 (FIG. 3A). That is, striped copper wirings 11 and 12 having the same pitch P are arranged on one side of the film 10 so as to be orthogonal to each other. The upper and lower sides of the intersection 8 need to be insulated, and an insulating resin 13 is placed on one copper wiring 12 and the other copper wiring 11 crosses over the insulating resin 13.

  The size of the transparent portion of the touch panel is used so as to overlap with an image display unit such as a liquid crystal display or an organic EL, so that it is at least as large as these image display units. However, if the entire range is not the input range of the touch panel, the mesh electrode may be omitted even if the range is a fluoroscopic range. Generally, it is painted black in a frame shape (decoration) so that it is not visible outside the range that requires perspective.

  The individual copper wirings 6, 7, 11, and 12 constituting the mesh electrode are all guided to the outer periphery of the film and connected to terminals for external connection (not shown. The same applies to the second and third embodiments). This wiring is called a lead-out wiring and inexpensive and low-resistance copper is preferable. In a portion that is not seen through, the line width can be increased within an allowable range. In this case, a range of approximately 0.02 to 0.5 mm is preferable. Any one of the mesh-like copper wirings 6 and 7 and the copper wiring for drawing out are collectively formed from a copper thin film laminated on the film 10. All copper wiring needs to be insulated from each other as long as they are used as sensors.

  Assuming that the width of the mesh opening 9 partitioned by the copper wiring is a and the wiring width of the light shielding portion is d, d / a = 0.05 at an opening ratio of 90% and d / a = 0.01 at an opening ratio of 98%. Degree. Since the line width d of the light-shielding metal is said to be invisible when it is approximately 20 μm or less, the side a of the opening is in the range of 400 to 2000 μm when the line width d = 20 μm. The narrower line width d = 10 μm needs to be in the range of 200 to 1000 μm and d = 5 μm in the range of 100 to 500 μm. For large displays, the line width is preferably about 50 μm or less, and the aperture ratio is 90% and a is about 1000 μm or more.

  Insulation of the upper and lower copper wirings at the mesh intersection 8 is preferably performed with an insulating resin layer 13 having a thickness of 1 to 2 μm interposed therebetween. If the side surface of the insulating resin layer 13 is nearly vertical, there is a risk of disconnection depending on the method of forming the overlying copper wiring 11, so it is desirable that the shoulder of the insulating resin layer 13 changes smoothly (different from the figure). After the lower layer copper wiring 12 is formed by a regular photolithography method, the resist remaining on the copper wiring is peeled off, and then a fine resist pattern can be formed again at the intersection 8 by the photolithography method.

The second embodiment is a mode shown in FIG. In the first embodiment, a mesh structure is formed on one side of the film. However, in this embodiment, striped copper wirings 11 and 12 having the same pitch are provided on both sides of the film 10, that is, the front and back surfaces, so that they are orthogonal to each other. It is arranged. In FIG. 1B, the solid line corresponds to the front surface, and the double line corresponds to the back surface. Since the film base 10 is between the copper wiring 11 and the copper wiring 12, it is not necessary to separately provide the insulating layer 13 at the intersection 8 as in the first embodiment. The top view is exactly the same as in the first embodiment. Two films having stripe electrodes on only one surface may be prepared and pasted back to back (FIG. 3C).
Alternatively, as shown in FIG. 3D, one copper wiring can be sandwiched between films. A broken line in the figure indicates a position where the bonding is performed using OCA (optical adhesive).

  In the third embodiment, as shown in FIG. 3 (e), the mesh structure 5 of the embodiment 1 is provided on the front and back of the film 10, and the front and back mesh structures are arranged so as to be shifted by a half pitch when viewed from above. It is a thing. This is the same as the first embodiment in which the pitch is halved, but there is an advantage that wiring processing becomes easier due to the wider pitch.

In Embodiments 1 to 3, the surface resistance of the copper wiring is preferably set to about 3Ω / □ or less. This is because the sensor sensitivity is higher when the resistance is lower. In Embodiment 2 and Embodiment 3, since the film 10 having a thickness of about 100 μm is interposed between the upper and lower wirings, the capacitance is preferably set in the range of 0.5 to 3 pF.

  Incidentally, the surface resistance was 0.3Ω / □ (by the four-terminal method) when the electrolytic copper foil was etched to form a mesh structure having a thickness of 13 μm, a line width of 10 μm, a pitch of 1000 μm, and an aperture ratio of 98%. The deposited copper foil had a thickness of 1.5 μm, a line width of 5 μm, a mesh pitch of 250 μm (substantially corresponding to the above-mentioned a), an aperture ratio of 93%, and a surface resistance of 3Ω / □. Although there are material differences in manufacturing method, the surface resistance can be controlled to a desired value within a range of 3Ω / □ or less.

  As a form of mounting the touch panel on the display device, as shown in FIG. 2A, the direction in which the colored pixels (light emitting pixels) repeat and the direction in which the stripe-shaped metal wiring extends are the same as in FIG. It is possible to incline by 45 ° as shown in FIG. However, in the case of tilting, if the pixel pitch p is the same, the stripe pitch P of the metal wiring becomes short (becomes 1 / √2), which makes it difficult to process.

  Next, the relationship between the pitch p of the colored pixels of the liquid crystal display and the pitch P of the metal wiring of the touch panel will be described using examples.

  A film-like touch panel was manufactured by a roll-to-roll method using a PET film having a thickness of 100 μm and a width of 300 mm. Regarding the film material, PET is preferable from the viewpoint of cost, but PEN or polyimide film can be used when heat resistance is required. In addition, polyethylene resin, polypropylene resin, methacrylic resin, cyclic polyolefin resin, polystyrene resin, acrylonitrile- (poly) styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer (ABS resin), A film having a thickness in the range of 20 to 50 μm manufactured from polyvinyl chloride resin, poly (meth) acrylic resin, polycarbonate resin, polyester resin, polyamide resin, polyamideimide resin, or the like can also be used.

  The copper thin film was obtained by laminating an electrolytic copper foil having a smooth surface with a thickness of 6 μm on the roll-shaped film substrate via an adhesive. Since the line width of the copper wire formed by etching the copper foil cannot be made thinner than the thickness of the copper foil, it is necessary to determine the type of the copper foil from the desired line width. When the line width is as thin as about 5 μm or less, it is preferable to use a copper thin film deposited on the film. Other than the electrolytic copper foil, a rolled copper foil can also be used.

  First, a roll-shaped PET film having copper foil laminated on the front and back was prepared, and patterning of the copper foil was carried out using a conventional photolithographic method.

  A resist was applied to one surface of the copper foil with a thickness of about 2 μm, and UV light was irradiated through a photomask provided with a stripe pattern constituting the mesh portion, an extraction electrode pattern, and the like. The other film surface was coated with a resist with the same thickness, and then exposed through a photomask. Next, development was performed using a 5% aqueous sodium carbonate solution to form a desired resist pattern. The copper foil exposed to the opening with about 60 degree ferric chloride solution is removed by etching to form a copper wiring pattern shown in the top view 1 (b) and the cross-sectional view 3 (b) on the front and back of the PET film. (Embodiment 2).

  A color filter substrate 1 having R, G, B colored pixels 2 and a black matrix 3 shown in FIG. 1A was manufactured by applying a conventional photolithography method using a colored resist. The size of the color filter substrate was equivalent to 4.2 inches, 4.8 inches, and 42 inches diagonally. The pixel pitch p in the horizontal direction was 84.2 μm, 360 μm, and 483 μm, respectively. The pixel pitch in the vertical direction is the same. Although details of the shape of the black stripe are omitted, in the 42-inch size, the thick part is 30 μm and the narrow part is 15 μm, and 4.2 and 4.8 inches are set to be thinner than this.

  The copper wiring pattern of the touch panel 5 overlaid on the color filter 1 has a mesh structure in which the opening when viewed from above is a square, and the line width is all 10 μm. The pitch P was varied depending on the pixel size on the color filter substrate side. Details are shown in Table 1 for each size. Since there are two ways to overlap the color filter and the touch panel, the parallel case is described as 0 ° and the tilted case as 45 °.

  Whether or not the moiré is visually recognized was determined by observing from above about 30 cm for a small substrate and about 1 m for 42 inches. The results are shown in Table 1 as ◯: no moire and x: moire. Moire was not visually recognized in the range of about 3.5 ± 0.1 times the pixel pitch.

  Next, the results when mounted on a large liquid crystal display will be described. In this case, the overlap was only parallel (0 °), and the pixel pitch was 629 μm (diagonal 55 inches), 484 μm (diagonal 42 inches), and 426 μm (diagonal 37 inches).

  A touch panel in which the mesh stripe pitch was changed in a range of 100 to 2000 μm at a pitch of 10 μm was created, and the occurrence of moiré was examined on the above display. The moire has a tendency to repeat the strength so that the stripe pitch is increased by an integral multiple of 1 / integer of the pixel pitch. However, it was hardly visible around 3.5 times the pixel pitch. Moire also repeats periodically, so it does not have to be exactly 3.5 times, but should be in the range of about 3.4 to 3.6 times. In a large display, about 3.5 ± 0.1 times is sufficient as the resolution as a position sensor.

  As a general tendency, when the moire is visually recognized, the outline is clearer and more conspicuous when the periodic pattern is parallel (0 °) than when it is inclined (45 °). When tilted, the contour of the moire became loose. In particular, as the mesh pitch increased, the contour of the moire became blurred and the normal feeling increased, and the margin for the moire increased. When tilted to 45 °, approximately 3.5 times the pixel pitch p corresponds to the diagonal of the mesh, so the mesh stripe pitch P becomes 1 / √2 that of the parallel case and becomes narrower. In FIG. 2, for reference, pixels (R, G, B) in which the pixel pitch and the touch panel stripe pitch are the same are inserted in the lower left.

1, color filter 2, colored pixels (R, G, B)
3. Black matrix 4, crossing part 5, touch panel (sensor part)
6, Y-direction electrode 7, X-direction electrode 8, electrode intersection 9, mesh opening 10, film base 11, metal wiring 12 on the film surface, metal wiring 13 on the film back surface, insulating resin p; pixel pitch P; Mesh pitch

Claims (5)

  A capacitive touch panel in the form of a film that is used over a display device including colored pixels periodically laid in two orthogonal directions at a pitch p, and the touch panel has a pitch P in one direction as P A film-like capacitance comprising a stripe-shaped metal wiring and a stripe-shaped metal wiring having a pitch P in a direction perpendicular to the metal wiring, wherein P is (3.5 ± 0.1) times p Type touch panel.   A capacitive touch panel in the form of a film that is used over a display device including colored pixels periodically laid in two orthogonal directions at a pitch p, and the touch panel has a pitch P in one direction as P A film-like film comprising a stripe-shaped metal wiring and a stripe-shaped metal wiring having a pitch P in a direction perpendicular to the metal wiring, wherein P is (3.5 / √2 ± 0.1) times p Capacitive touch panel.   The film-like capacitive touch panel according to claim 1, wherein a line width of the metal wiring is 50 μm or less.   The method of using a film-like capacitive touch panel according to claim 1 or 3, wherein a repeating direction of the colored pixels of the display device is the same as a direction in which the stripe-shaped metal wiring extends.   4. The method of using a film-like capacitive touch panel according to claim 2 or 3, wherein a repeating direction of the colored pixels of the display device and a direction in which the striped metal wiring extends form an angle of 45 [deg.]. .

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