JP2018060345A - Electronic device and touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic device capable of avoiding the occurrence of visibly shaded stripe-shaped printing unevenness.SOLUTION: An electronic device includes an electrode (first sensor electrode array 61) composed of a first fine wire mesh, a lead wire 63, and a second fine wire mesh which are made of a cured conductive ink film. A plurality of wiring patterns including pads 64 for mediating connections between the electrodes and the lead wire 63 are arranged on a surface of a base material, all the pads 64' are arranged along one direction on the surface, and all the electrodes are positioned on one side across an array of the pads 64' while all the lead wires 63 are located on the other side, and all the intervals between adjacent pads in the one direction are 100 μm or less.SELECTED DRAWING: Figure 5

Description

  The present invention relates to an electronic device in which a wiring pattern is formed by printing, and more particularly to a touch panel.

  In recent years, printing methods that are excellent in productivity and advantageous in terms of manufacturing cost have been used to form electrode patterns and wiring patterns of various electronic devices such as touch panels, touch sensors, membrane switches, and organic EL. . In particular, gravure offset printing is attracting attention as being suitable for forming high-definition patterns.

  Patent Document 1 describes that a touch sensor is formed by gravure offset printing as described above, and FIGS. 8 and 9 illustrate the configuration of a touch key including the touch sensor described in Patent Document 1 and the touch sensor. The gravure offset printing machine used for manufacture of this is shown.

  As shown in FIG. 8, the touch key includes a touch sensor 10 and a touch sensor driving circuit 15. The touch sensor 10 connects the substrate 11, the plurality of mesh electrodes 12 formed on the substrate 11, the outer edge wiring 13 provided on the outer edge of the mesh electrode 12, the outer edge wiring 13, and the touch sensor driving circuit 15. Connection wiring 14 is provided. The mesh electrode 12 has a mesh shape, and the outer edge wiring 13 is formed so as to extend along the upper side of the mesh electrode 12 in FIG.

  The mesh electrode 12, the outer edge wiring 13 and the connection wiring 14 are formed by simultaneously printing on the substrate 11 using a gravure offset printing machine and then curing.

  As shown in FIG. 9, the gravure offset printing machine 20 includes a plate table 21, a substrate table 22, a doctor blade 23, a transfer roller 24, an apparatus frame 25, and a dispenser (not shown). Yes. An intaglio plate (gravure plate) on which a concave pattern 26 having a mesh-like recess 26a, an outer-edge recess 26b, and a connection recess 26c respectively corresponding to the mesh electrode 12, the outer edge wiring 13, and the connection wiring 14 of the touch sensor 10 is formed on the plate table 21. 27) is placed and fixed, and the substrate 11 which is a printing medium is placed and fixed on the base material table 22. The doctor blade 23 and the transfer roller 24 are movable along the X axis and the Z axis, and the dispenser is also movable along the X axis and the Z axis.

  The conductive paste 28 is filled in the concave pattern 26 of the intaglio 27 by sliding the doctor blade 23 along the X axis while supplying the conductive paste 28 onto the intaglio 27 by the dispenser. . The conductive paste 28 filled in the concave pattern 26 is received by the transfer roller 24, and the print pattern held on the transfer roller 24 is transferred to the substrate 11. By heating and curing the printed pattern transferred to the substrate 11, the mesh electrode 12, the outer edge wiring 13, and the connection wiring 14 of the touch sensor 10 are completed.

Japanese Patent Laid-Open No. 2015-45890

  As described above, Patent Document 1 describes that the wiring pattern of the touch sensor is formed by gravure offset printing. However, in the wiring pattern as shown in FIG. The wiring element that mediates the connection between the wiring 12 and the connection wiring 14 is a line-shaped outer edge wiring 13, and the outer edge recess 26 b of the intaglio 27 corresponding to the outer edge wiring 13 is parallel to the doctor blade 23 as shown in FIG. 9. As a result, the doctor blade 23 may fall into the outer edge concave portion 26b during the squeezing process to scrape the conductive paste (conductive ink).

  Therefore, in order to avoid such a problem, the wiring element that mediates the connection between the mesh electrode 12 and the connection wiring 14 is not the line-shaped outer edge wiring 13 but the edge (upper side) of the mesh electrode 12. A pad made of a fine line mesh composed of line segments obliquely extending in the line direction, that is, line segments obliquely extending in the extending direction of the doctor blade 23, and further extending parallel to the extending direction of the doctor blade 23 of the connection wiring 14 The structure which makes the part which has a wavy line can be considered.

  Based on the above idea, sensor electrode rows arranged in the sensor region, lead wires for external connection provided on the frame portion surrounding the sensor region, and pads that mediate connection between the sensor electrode rows and the lead wires In the touch panel having a wiring pattern including: a sensor electrode array is configured by a first fine line mesh; a pad is configured by a second fine line mesh having a higher density than the first fine line mesh; When the wiring pattern was formed using gravure offset printing with the part extending parallel to the extending direction of the blade as a wavy line, the problem of ink scraping due to the drop of the doctor blade into the concave part of the gravure plate was resolved, Grayscale printing unevenness that can be visually recognized corresponding to the position of the pad occurs throughout the entire display area (sensor area) of the touch panel. I have found a new problem.

  Specifically, the sensor electrode array is relatively dark in the downstream region in the squeezing direction of the part where the pad is located, and relatively light in the downstream region in the squeezing direction of the part of the gap between the pads where the pad is not located. The fine line mesh is printed.

  An object of the present invention is to provide an electronic device and a touch panel in which such visible printing shading unevenness does not occur.

  According to invention of Claim 1, it consists of the film | membrane of the hardened | cured conductive ink, and is comprised by the electrode comprised by the 1st fine wire mesh, the leader line, and the 2nd fine wire mesh, and the connection of an electrode and a leader line is made A plurality of wiring patterns including an intermediary pad are arranged on the surface of the base material, all the pads are arranged along one direction on the surface, and all are arranged on one side of the pad arrangement. In the electronic device in which all of the lead lines are located on the other side, the intervals between adjacent pads in the one direction are all 100 μm or less.

  According to a second aspect of the present invention, in the first aspect of the present invention, all the electrodes have straight edges parallel to the one direction, and all the pads are extended along the edges to connect to the electrodes. And a projecting portion projecting from the straight portion to the other side and connected to the lead line, and all the straight portions are aligned on a straight line extending in the one direction.

  In the invention of claim 3, in the invention of claim 1 or 2, the first fine wire mesh and the second fine wire mesh are constituted by line segments obliquely intersecting both the one direction and the direction orthogonal to the one direction, The lead line has a wavy shape extending in the one direction.

  According to a fourth aspect of the present invention, in any one of the first to third aspects of the present invention, the second fine wire mesh has a higher density than the first fine wire mesh.

  According to the invention of claim 5, a sensor electrode array composed of a first fine line mesh and arranged in a rectangular sensor region, a leader line provided in a frame portion surrounding the sensor region, and a second fine line mesh The touch panel is formed of a conductive ink film having a hardened wiring pattern including a sensor electrode array and a pad that mediates connection of the lead line, and the pads are arranged along the rectangular side, Of the pads arranged along the same line, at least one pad located on one side has an interval between adjacent pads of 100 μm or less.

  In the invention of claim 6, in the invention of claim 5, the first fine line mesh and the second fine line mesh are composed of line segments obliquely intersecting the sides of the rectangle, and among the lead lines, the spacing between adjacent pads is The shape of the portion extending in parallel with the direction in which the pads are all arranged to be 100 μm or less is a wavy line.

  In the invention of claim 7, in the invention of claim 5 or 6, the second fine wire mesh is made higher in density than the first fine wire mesh.

  According to the present invention, it is possible to obtain an electronic device and a touch panel that can be visually recognized and does not cause uneven shading of printed stripes, and to provide an electronic device and a touch panel that have an excellent display portion that is attractive in that respect. Can do.

The figure for demonstrating the structure outline | summary of a touchscreen. The elements on larger scale which show the detail of the 1st sensor electrode row | line | column, pad, and leader line of the touch panel shown in FIG. The elements on larger scale which show the detail of the 2nd sensor electrode row | line | column of the touch panel shown in FIG. The elements on larger scale which show the detail of the leader line of the touchscreen shown in FIG. The elements on larger scale which show the principal part detail of one Example of the touchscreen by this invention. A is a figure which shows a wavy line-shaped wiring pattern, B is a figure for demonstrating the tailing and bleeding of conductive ink. FIG. 4A is a diagram illustrating a configuration example of a gravure plate corresponding to a wavy line-shaped wiring pattern, and B is a diagram illustrating another configuration example of a gravure plate corresponding to a wavy line-shaped wiring pattern. The figure which shows the conventional structural example of a touch sensor. The figure which shows the gravure offset printing machine used for manufacture of the touch sensor shown in FIG.

  First, a description will be given of the configuration of a capacitive touch panel that has triggered the discovery of a new problem in which uneven shading that can be visually recognized corresponding to the position of the pad occurs.

  FIG. 1 shows an outline of the configuration of a capacitive touch panel. In FIG. 1, 30 indicates a transparent substrate. The capacitive touch panel has a configuration in which, for example, a first conductor layer, an insulating layer, a second conductor layer, and a protective film are sequentially stacked on the transparent substrate 30.

  Although the detailed illustration of the sensor electrode array is omitted in FIG. 1, the sensor electrode array includes a plurality of first sensor electrode arrays and a plurality of second sensor electrode arrays, and the plurality of first sensor electrode arrays are the first conductors. The plurality of second sensor electrode arrays are formed by a second conductor layer that is insulated from the first conductor layer by an insulating layer. In FIG. 1, a portion surrounded by a rectangular frame indicates a sensor region 40 where the sensor electrode array is located. The outer side of the rectangular frame forms a frame portion 50 that surrounds the sensor region 40.

  FIG. 2 shows details of the first sensor electrode array 61, the dummy electrode 62, the lead-out line 63, and the pad 64 formed by the first conductor layer, and FIG. 3 is formed by the second conductor layer. The details of the second sensor electrode array 71 and the dummy electrode 72 are shown. 2 and 3 show the upper left part of the sensor region 40 in FIG. 1 together with a part of the frame portion 50.

  In the sensor region 40, a dummy electrode 62 is formed together with the first sensor electrode array 61 as shown in FIG. 2, and a dummy electrode 72 is formed together with the second sensor electrode array 71 as shown in FIG. Yes. The dummy electrodes 62 and 72 are formed so that the first sensor electrode row 61 and the second sensor electrode row 71 are not conspicuous, respectively.

  The first sensor electrode array 61, the dummy electrode 62, the second sensor electrode array 71, and the dummy electrode 72 are fine-line meshes (the first specification) composed of line segments obliquely intersecting the sides of the rectangular sensor region 40. The first sensor electrode row 61 insulated from the dummy electrode 62 and the second sensor electrode row 71 insulated from the dummy electrode 72 are respectively formed by dividing predetermined portions of the fine wire mesh. ing. In this example, the unit cell of the first fine line mesh is a rhombus having a side length of 400 μm, and the line width of the fine lines constituting the mesh is 7 μm. The first sensor electrode array 61 and the dummy electrode 62, and the second sensor electrode 71 and the dummy electrode 72 are separated and insulated at intervals of about 20 μm.

  The first sensor electrode array 61 includes a plurality of island electrodes 61a arranged in the X direction parallel to the long side 41 of the sensor region 40 having a rectangular shape, and a connecting portion 61b that connects the adjacent island electrodes 61a. . A plurality of first sensor electrode rows 61 are arranged in parallel in the Y direction parallel to the short side 42 of the rectangular sensor region 40. The second sensor electrode array 71 includes a plurality of island-shaped electrodes 71a arranged in the Y direction and a connecting portion 71b that connects adjacent island-shaped electrodes 71a. A plurality of second sensor electrode rows 71 are arranged in parallel in the X direction.

  The first sensor electrode array 61 and the second sensor electrode array 71 intersect with each other while being insulated from each other. At this time, the first sensor electrode array 61 and the second sensor electrode array 71 are overlapped with each other so as to intersect each other at a midpoint that divides the rhombus sides of the unit cell into 200 μm portions, that is, the first conductor. When the first sensor electrode row 61 and dummy electrode 62 of the layer and the second sensor electrode row 71 and dummy electrode 72 of the second conductor layer are correctly overlapped (without error), the length of one side is 200 μm. Are uniformly formed in the sensor region 40. The connecting portions 61b and 71b are positioned so as to overlap each other.

  As shown in FIG. 1, lead-out lines 63 and 73, terminals 81, and ground wirings 82 are formed in the frame portion 50. Further, although not shown in FIG. 1, pads are formed. Lead lines 63 are drawn from both ends in the X direction of each first sensor electrode row 61 via pads 64 (see FIG. 2), and lead lines 73 are drawn from one end in the Y direction of each second sensor electrode row 71. Each is pulled out through the pad. In FIG. 1, a plurality of leader lines 63 and 73 arranged on the frame 50 are shown only at those located at both ends of the arrangement, and those other than those located at both ends are not shown.

  The terminals 81 are arranged and formed at the center of one long side of the rectangular transparent substrate 30, and the lead lines 63 and 73 extend to the terminal 81 and are connected to the terminal 81. The ground wiring 82 is formed on the peripheral portion of the frame portion 50 so as to surround the lead lines 63 and 73. The ground wiring 82 is also connected to the terminal 81.

  The lead wire 73 and the terminal 81 are formed of the first conductor layer, similarly to the lead wire 63, and the ground wiring 82 is formed of both the first and second conductor layers.

  The pad 64 that mediates the connection between the first sensor electrode array 61 and the lead line 63 and the pad that mediates the connection between the second sensor electrode array 71 and the lead line 73 are both omitted. It consists of a fine line mesh (second fine line mesh) composed of line segments obliquely intersecting the side 41 and the short side 42, and the second fine line mesh is the first sensor electrode array 61, 71 constituting the first and second sensor electrode rows 61, 71. The density is higher than that of one fine wire mesh. In this example, the unit cell of the second fine line mesh is a square having a side length of about 40 μm, and the line width of the fine lines constituting the mesh is 10 μm.

  Although the detailed illustration of the terminal 81 and the ground wiring 82 is omitted, like the pad 64, the terminal 81 and the ground wiring 82 are formed of a fine line mesh having a higher density than the first fine line mesh constituting the first and second sensor electrode rows 61 and 71. Has been.

  On the other hand, the lead lines 63 and 73 are not a mesh but a line-like wiring. In this example, the lead line 63 is drawn from the pad 64 and parallel to the short side 42 of the sensor region 40, that is, in the Y direction. The portion extending long is made up of wavy lines as shown in FIG. FIG. 4 shows a portion where a number of lead lines 63 arranged in the lower left portion of the frame portion 50 in FIG. 1 change in the extending direction from the Y direction to the X direction.

  The first and second conductor layers having the above-described configuration are printed and formed by gravure offset printing using a conductive ink containing conductive particles such as silver. The squeezing direction S of the doctor blade with respect to the gravure plate that defines the wiring pattern of the conductor layer is the X direction parallel to the long side 41 of the sensor region 40 as indicated by an arrow in FIG.

  In this example, as described above, the wiring patterns other than the lead lines 63 and 73 are formed by a fine line mesh composed of line segments oblique to the squeezing direction S of the doctor blade. Since the portion extending long in the Y direction of the line 63 (the extending direction of the blade edge of the doctor blade) is formed by a wavy line, the doctor blade falls into the concave portion of the gravure plate defining these wiring patterns, and the conductive ink is scraped off. It is possible to eliminate the occurrence of problems such as.

  On the other hand, in the touch panel having such a configuration, as described above, the squeezing of the portion of the gap between the pads 64 where the pad 64 is not relatively located in the downstream basin in the squeezing direction S of the portion where the pad 64 is located. In the downstream region in the direction S, the phenomenon was that the thin line mesh in the sensor region 40 was printed relatively lightly, and the dark and light striped print unevenness was generated.

  It has been found that this uneven printing appears more remarkably as the number of times of printing is repeated with the same gravure offset printing apparatus, and the difference in shading is emphasized.

  Therefore, the present inventors repeatedly wear the doctor blade edge on the gravure concave portion corresponding to the pad 64 made of a high-density fine wire mesh, thereby causing partial wear on the blade edge. Estimated that the deterioration of the squeezing ability (scraping ability) due to the cause of printing unevenness, and created a solution to make the spacing between pads smaller than the human-visible resolution As a result, the effect of eliminating uneven printing was obtained.

  FIG. 5 shows the details of the main part of an embodiment of the touch panel according to the present invention that can eliminate the uneven printing, and FIG. 5 corresponds to FIG. 2 described above.

  A pad 64 ′ formed by the second fine line mesh and arranged in the Y direction along the short side 42 of the rectangular sensor region 40 has a linear shape parallel to the Y direction of the first sensor electrode array 61. A straight portion 65 extending along the edge and connected to the first sensor electrode array 61, and a protrusion 66 protruding from the straight portion 65 toward the outer edge of the frame portion 50 and connected to the lead line 63. With. The straight portions 65 of all the pads 64 ′ are aligned on a straight line. In this example, the distances d between adjacent pads 64 ′ arranged in this way are all 100 μm or less. In addition, the pad d located on the other end side of the first sensor electrode array 61 has an adjacent pad interval d of 100 μm or less. By setting the inter-pad spacing d in this way, the uneven shading of printing that can be visually recognized is eliminated.

  Here, the grounds for setting the upper limit of the inter-pad spacing d to 100 μm will be described.

  As described above, when the fine wire mesh of the first conductor layer and the fine wire mesh of the second conductor layer are correctly superimposed (without error), a rhombus lattice having a side length of 200 μm is formed in the sensor region 40. That is, it is uniformly formed on the display portion. In this state, nothing can be visually recognized with the naked eye, that is, the fine lines constituting the fine line mesh cannot be visually recognized.

  However, if the first conductor layer and the second conductor layer are misaligned and the rhombus crossing is performed at a position deviated from the midpoint of the side, a set of adjacent thin lines is formed. The problem of drawing a relatively dark line that is visible as if it were one thick line occurs.

  For this reason, the permissible range of the misalignment of the first conductor layer and the second conductor layer is set to 50 μm for strict specifications and to 100 μm for loose specifications. In other words, it is required that the fine lines constituting the fine line mesh be separated from each other by 150 μm or more in a strict specification and 100 μm or more in a loose specification.

  Therefore, in this embodiment, the upper limit of the inter-pad spacing d is set to 100 μm on the basis of the loose specification. If the inter-pad spacing d is set to 100 μm or less, the width of the light portion of the dark and light stripe-shaped printing unevenness is less than the visual resolution, so the light portion is not recognized, that is, the printing unevenness is not recognized.

  In addition, as a more preferable embodiment for improving the appearance of the display unit, it is possible to employ a manufacturing condition in which the upper limit of the inter-pad spacing d is 50 μm so as to be surely lower than the visual resolution.

  Furthermore, in order to eliminate the visibility of printing unevenness, as the most preferred embodiment, it is possible to employ a manufacturing condition in which the upper limit of the inter-pad spacing d is 10 μm on the basis of the spacing spacing that ensures insulation.

  In addition, the narrowing of the inter-pad spacing d is required in this way when the pads are made of a high-density fine line mesh and a plurality of pads are arranged in the extending direction of the blade edge of the doctor blade. In this regard, when there is a pad that meets this condition on only one side of the rectangular sensor region 40, the pad interval d between the pads located on that side is narrowed. Moreover, the shape of the part extended in parallel with the arrangement direction of the pad arrange | positioned among the leader lines in which the space | interval d between pads is narrowed is made into a wavy line.

  FIG. 6A shows a wavy line shape applied to a wiring pattern, and a wiring pattern 90 forming a wavy line has a wavy line composed of a triangular wave.

  When the wavy line of the wiring pattern forming the wavy line is a triangular wave as shown in FIG. 6A, the printed wiring pattern 90 is likely to have a shape defect as shown in FIG. 6B. That is, the tailing of the conductive ink marked with a may occur from the folded portion (corner) of the triangular wave located on the downstream side with respect to the squeezing direction S, and the bleeding of the conductive ink marked with b may cause the folded portion of the triangular wave. May occur.

  In order to prevent such tailing a and bleeding b, as shown in FIG. 7A, the convex portion 102 is formed in the concave portion 101 of the gravure plate 100 corresponding to the wavy wiring pattern 90 to reduce the amount of conductive ink. It is effective to do. As a result, a void (a space without a film) or a dent corresponding to the convex portion 102 of the gravure plate 100 is formed in the wavy wiring pattern 90. The convex portion 102 is preferably formed so as to be located at the folded portion of the wavy line, and more preferably formed so as to be shifted in the squeezing direction S as shown in FIG. 7B.

  In addition, in order to suppress the resistance value and avoid the risk of disconnection, the line-like lead lines 63 and 73 of the touch panel are formed with wiring thicker than the fine lines constituting the fine line mesh. It is easy for printing defects to occur due to the remaining conductive ink. Forming the convex part 102 in the concave part 101 of the gravure plate 100 is preferable also in preventing the occurrence of such printing defects. In this respect, it is preferable to form a convex portion not only in the wavy line portion of the wiring pattern but also in the concave portion of the gravure plate corresponding to the straight portion.

  The touch panel according to the present invention has been described above. However, the present invention is not limited to the touch panel, and an electronic device such as a touch sensor as shown in FIG.

  That is, the electrode is composed of a cured conductive ink film, and includes an electrode composed of a first fine line mesh, a lead line, and a pad composed of a second fine line mesh that mediates the connection between the electrode and the lead line. A plurality of wiring patterns are arranged on the surface of the substrate, all the pads are arranged along one direction on the surface of the substrate, and all the electrodes are located on one side of the pad arrangement. The electronic device in which all the leader lines are located on the other side is an object, and in such an electronic device, the intervals between adjacent pads arranged in one direction are all set to 100 μm or less.

DESCRIPTION OF SYMBOLS 10 Touch sensor 11 Board | substrate 12 Mesh-like electrode 13 Outer edge wiring 14 Connection wiring 15 Touch sensor drive circuit 20 Gravure offset printing machine 21 Plate table 22 Base table 23 Doctor blade 24 Transfer roller 25 Apparatus frame 26 Concave pattern 26a Mesh-like recessed part 26b Outer edge Concave portion 26c Connection concave portion 27 Intaglio plate 28 Conductive paste 30 Transparent substrate 40 Sensor region 41 Long side 42 Short side 50 Frame portion 61 First sensor electrode row 61a Island electrode 61b Connection portion 62 Dummy electrode 63 Lead lines 64, 64 'Pad 65 Straight line portion 66 Projection portion 71 Second sensor electrode array 71a Insular electrode 71b Connection portion 72 Dummy electrode 73 Lead wire 81 Terminal 82 Ground wiring 90 Wiring pattern 100 Gravure plate 101 Concave portion 102 Convex portion

Claims (7)

An electrode made of a hardened conductive ink and comprising a first fine wire mesh, a leader line, and a second fine wire mesh, comprising a pad for mediating connection between the electrode and the lead wire. A plurality of wiring patterns are arranged on the surface of the substrate, all the pads are arranged along one direction on the surface, and all the electrodes are positioned on one side of the pad arrangement. An electronic device in which all the leader lines are located on the other side,
All the intervals between the pads adjacent in the one direction are 100 μm or less. The electronic device according to claim 1.
All the electrodes have straight edges parallel to the one direction;
All the pads include a straight portion that extends along the edge and connects to the electrode, and a protrusion that protrudes from the straight portion to the other side and connects to the lead line,
An electronic device, wherein all the straight portions are aligned on a straight line extending in the one direction. The electronic device according to claim 1 or 2,
The first fine line mesh and the second fine line mesh are composed of line segments that obliquely intersect both the one direction and the direction orthogonal to the one direction,
The electronic device according to claim 1, wherein the lead wire has a wavy shape extending in the one direction. The electronic device according to any one of claims 1 to 3,
The electronic device, wherein the second fine wire mesh has a higher density than the first fine wire mesh. A sensor electrode array composed of a first fine wire mesh and arranged in a rectangular sensor region, a lead line provided in a frame portion surrounding the sensor region, and a second thin wire mesh, the sensor electrode array And a touch panel made of a conductive ink film in which a wiring pattern including a pad that mediates connection of the lead wire is cured,
The pads are arranged along the sides of the rectangle;
Among the pads arranged along the rectangular side, at least one of the pads located on one side has an interval between adjacent pads of 100 μm or less. The touch panel according to claim 5,
The first fine line mesh and the second fine line mesh are composed of line segments obliquely intersecting the sides of the rectangle,
2. A touch panel, wherein, among the lead lines, the shape of a portion extending in parallel with the arrangement direction of the pads arranged such that the distance between adjacent pads is 100 μm or less is a wavy line. The touch panel according to claim 5 or 6,
The touch panel, wherein the second fine line mesh has a higher density than the first fine line mesh.