Touch Sensor with a Conductive Line Having Different Widths
In one embodiment, a touch sensor includes one or more meshes of conductive material. Each of the meshes includes a plurality of conductive lines. A first one of the conductive lines has a first portion and a second portion. The first portion is wider than the second portion.
This application is a continuation under 35 U.S.C. §120 of U.S. patent application Ser. No. 13/089,061, filed 18 Apr. 2011.
TECHNICAL FIELDThis disclosure generally relates to touch sensors.
BACKGROUNDA position sensor can detect the presence and location of a touch by a finger or by an object, such as a stylus, within an area of an external interface of the position sensor. In a touch sensitive display application, the position sensor enables, in some circumstances, direct interaction with information displayed on the screen, rather than indirectly via a mouse or touchpad. Position sensors can be attached to or provided as part of devices with a display. Examples of devices with displays include, but are not limited to, computers, personal digital assistants, satellite navigation devices, mobile telephones, portable media players, portable game consoles, public information kiosks, and point of sale systems. Position sensors have also been used as control panels on various appliances.
There are a number of different types of position sensors. Examples include, but are not limited to resistive touch screens, surface acoustic wave touch screens, capacitive touch screens, and the like. A capacitive touch screen, for example, may include an insulator coated with a transparent conductor in a particular pattern. When an object, such as a finger or a stylus, touches the surface of the screen there may be a change in capacitance. This change in capacitance may be sent to a controller for processing to determine where the touch occurred on the touch screen.
In a mutual capacitance configuration, for example, an array of conductive drive electrodes or lines and conductive sense electrodes or lines can be used to form a touch screen having capacitive nodes. A node may be formed where a drive electrode and a sense electrode overlap. The electrodes may be separated by an insulator to avoid electrical contact. The sense electrodes may be capacitively coupled with the drive electrodes at the nodes. A pulsed or alternating voltage applied on a drive electrode may therefore induce a charge on the sense electrodes that overlap with the drive electrode. The amount of induced charge may be susceptible to external influence, such as from the proximity of a nearby finger. When an object touches the surface of the screen, the capacitance change at each node on the grid can be measured to determine the position of the touch.
While clear conductors such as ITO may be used for electrodes, opaque metal electrodes also may be used. The opaque metal electrodes may be made of a conductive mesh of thin conductors, which may be of copper, silver or other conductive materials. The thin conductors may be made very thin as to be substantially invisible to the naked eye.
SUMMARYAn electrode pattern for a position sensing panel may have an array of mesh cells formed by sinusoidaly shaped conductive lines extending between vertices of the mesh cells.
The figures depict one or more implementations in accordance with the present disclosure, by way of example, not by way of limitation. In the figures, like reference numerals refer to the same or similar elements.
In the following detailed description, numerous specific details are set forth by way of examples. In order to avoid unnecessarily obscuring examples of the present disclosure, those methods, procedures, components, and/or circuitry that are well-known to one of ordinary skill in the art have been described at a relatively high level.
Reference is now made in detail to the examples illustrated in the accompanying figures and discussed below.
A display may be overlaid with a touch position-sensing panel to implement a touch sensitive display device. Exemplary displays include liquid crystal displays, active matrix liquid crystal displays, electroluminescent displays, electrophoretic displays, plasma displays, cathode-ray displays, OLED displays, or the like. It will be appreciated that light emitted from the display may be able to pass through the touch position-sensing panel with minimal absorption or obstruction.
The panel 1 includes a number of electrodes 4(X) and a number of electrodes 5(Y) provided on opposite faces 3a and 3b of the substrate 3. The electrodes 4(X), which may be on face 3b, may be arranged in one direction and the electrodes 5(Y), which may be on face 3a, may be arranged in a direction different than the direction of electrodes 4(X). Other conductive tracks may also be provided on the opposing faces 3a and 3b of the substrate 3. Such other conductive tracks may provide drive and sense connections to the electrodes 4(X) and 5(Y). The substrate 3 may be provided adjacent to the display 2 such that electrodes 4(X) are arranged between the display 2 and the substrate 3. An adhesive layer 6 of an optically clear adhesive may be between the electrodes 4(X) and a transparent covering sheet 7. Another adhesive layer 8 of an optically clear adhesive may be between the electrodes 5(Y) and a transparent covering sheet 9. A gap may be formed between the display 2 and the transparent covering sheet 7.
The transparent covering sheet 7 and the adhesive layer 6 of optically clear adhesive may encapsulate the electrodes 4(X), and any other conductive tracks formed on face 3b of the substrate 3. The transparent covering sheet 9 and the adhesive layer 8 of optically clear adhesive may encapsulate the electrodes 5(Y), and any other conductive tracks formed on face 3a of the substrate 3. The encapsulation of the electrodes 4(X) and 5(Y), and any other conductive tracks, may provide protection from physical and environmental damage. In some examples, portions of the conductive tracks may be exposed to provide connection points for connection to external drive circuitry.
In the mutual capacitance example, electrodes 4(X) may be drive electrodes provided on face 3b of the substrate 3, and electrodes 5(Y) may be sense electrodes provided on the opposing face 3a of the substrate 3. Capacitive sensing channels may be formed by capacitive coupling nodes in the localized regions at an around where electrodes 4(X) and 5(Y) cross over each other and are separated by the substrate 3.
One or both of the sets of electrodes 4(X) and 5(Y) may be formed from a conductive material, such as a metal. Suitable metals include copper, silver, gold, aluminum, tin and other metals used in conductive wiring. In some examples, the sense electrodes may be patterned in narrow lines to allow most of the light emitted from the display and incident on the sense electrode layer to pass through the electrode layer between the narrow metal lines. The narrow lines may be no more than 20 microns wide. An exemplary range may be 1-5 microns. Narrower lines have reduced visibility to the naked eye. By forming electrodes 4(X) or 5(Y) from narrow conductive lines, the position-sensing panel may be formed such that no more than about 10% of the active area is covered by the metal lines of the electrodes. Less coverage of the active area allows for greater transparency of the position-sensing panel reduces visibility of the electrodes to the human eye and reduces perceptible darkening or other loss of display quality. An exemplary coverage may be less than 5%.
In some examples, the electrodes 4(X) may be formed from a clear conductive material and the electrodes 5(Y) may be formed from narrow conductive lines. In other examples, the electrodes 4(X) may be formed from narrow conductive lines and the electrodes 5(Y) may be formed from a clear conductive material.
In an example where other conductive tracks in addition to the electrodes 4(X) and 5(Y) are provided on the substrate 3, the other conductive tracks may also be formed from a clear conductive material or narrow conductive lines, in a manner similar to the electrode layers 4(X) and 5(Y). In an example where the other conductive tracks, or parts of the other conductive tracks, lie outside a visible region of the display 2, the light-transmissibility of the other conductive tracks is of no concern.
In other examples, the electrode pattern may be formed by a number of square shaped mesh cells 13a that do not have four metal lines meet at vertices. Instead of the connection points of the conductive lines being the vertices of the square shaped mesh cells as shown in
In other examples, the mesh pattern may be made up of an array of other regular trapezoid shaped mesh cells. In one example, the mesh pattern may be made up of an array of two different diamond shaped mesh cells which tessellate to form the mesh pattern.
An example of a portion of an electrode pattern 14 is shown in
In the illustrated example of
The sinusoidal shape of the conductive lines 15 as shown in
The sinusoidal shape of the conductive lines 15 in the illustrated example may reduce the visibility of reflections from the conductive lines when a touch position sensing panel is illuminated by light from a point illumination source, such as the sun on a clear day. The sinusoidal shape of the conductive lines 15 may tend to distribute or disperse the apparent position on the touch position sensing panel of such reflections, and so may minimize the perceived visibility of repetitive reflection patterns. Such repetitive reflection patterns are readily perceived by the human eye.
In
In some examples, the sinusoidal conductive lines may be formed as continuous curves. In other examples, the sinusoidal conductive lines may be formed by a number of short straight line sections arranged in a triangular waveform shape to approximate a sinusoidal shape. In other examples, the conductive lines may be shaped as other types of curves. In some examples, the conductive lines may be shaped as curves extending from a path that would be taken by a straight line between the vertices linked by the conductive metal line.
Another example of an electrode pattern 18 is shown in
In other examples, the mesh pattern may be made up of an array of other substantially regular trapezoid shaped mesh cells. In one example, the mesh pattern may be made up of a tessellated array of two different substantially diamond shaped mesh cells.
In other examples, the amplitude of the sinusoidal shape of the sinusoidal conductive lines may be varied. For example, the distance the peaks of the sinusoidal shaped conductive lines extend away from a path that would be taken by a straight line between the vertices linked by the sinusoidal conductive lines may be varied. The amplitude of the sinusoidal shape of the sinusoidal conductive lines may be varied between the different sinusoidal conductive lines, and may also be varied at different points along one, some or all of the sinusoidal conductive lines.
A portion of another electrode pattern 22 is shown in
For example, as shown in
In
As shown, the sinusoidal conductive lines in
In an example of an electrode using the cell of
In other examples, the wavelength of the sinusoidal shape of the sinusoidal conductive lines may be varied. That is, the distance between the crossing points where the sinusoidal shaped conductive lines cross a path that would be taken by a straight line between the vertices linked by the sinusoidal conductive lines may be varied. The wavelength of the sinusoidal shape of the sinusoidal conductive lines may be varied between the different sinusoidal conductive lines and/or may be varied at different points along one, some or all of the sinusoidal conductive lines.
A portion of another electrode pattern 26 is shown in
As shown in
In this example, the sinusoidal conductive lines 27 may have varying wavelengths. As is illustrated in
As shown, the sinusoidal conductive lines of
In other examples, both the amplitude and the wavelength of the sinusoidal shape of the sinusoidal conductive lines may be varied. The amplitude and/or the wavelength of the sinusoidal shape of the sinusoidal conductive lines may be varied between the different sinusoidal conductive lines, and may also be varied at different points along one, some or all of the sinusoidal conductive lines.
A portion of another electrode pattern 30 is shown in
In the example of
In this example, the conductive lines 31 have varying amplitudes and varying wavelengths of the sinusoids. As is illustrated in
As shown, the sinusoidal conductive lines in
In other examples, a phase change between the sinusoidal shapes of the sinusoidal conductive lines where the sinusoidal conductive lines interconnect at connection points may be varied.
A portion of another electrode pattern 34 is shown in
In the illustrated example, four sinusoidal conductive lines 35a to 35d and the connection point 36 of those four lines 35a to 35d may be part of an electrode pattern 34 defining an array of substantially square shaped mesh cells arranged in a layer. As discussed regarding the previous examples, the sinusoidal conductive lines may be sinusoidal shapes extending to either side of the path of a straight line extending between adjacent connection points or vertices of the electrode pattern 34. In the exemplary orientation, because the electrode pattern 34 may define an array of substantially square shaped mesh cells, a sinusoidal conductive metal line 35a and a sinusoidal conductive metal line 35c may extend to either side of the connection point 36 in one direction and may be aligned with one another. Similarly, a sinusoidal conductive metal line 35b and a sinusoidal conductive metal line 35d may extend to either side of the connection point 36 in another direction and may be aligned with one another. The sinusoidal metal lines 35a and 35c extend perpendicularly to the sinusoidal metal lines 35b and 35d.
In the example, the sinusoidal waveform of the conductive metal line 35a and the sinusoidal conductive metal line 35c may be in phase where the two conductive lines 35a and 35c meet at the connection point 36. Similarly, the sinusoidal waveform of the conductive metal line 35b and the sinusoidal waveform of the conductive metal line 35d may be in phase where the two conductive lines 35b and 35d meet at the connection point 36.
An example of a portion of another electrode pattern 37 is shown in
In
In
In other examples, the width of the conductive lines may be varied along their length.
A portion of another electrode pattern 40 is shown in
A portion of another electrode pattern 42 is shown in
In
The examples shown in
In the examples of
The positions of some of the vertices 53 may vary. In the example, a vertex 53a may be a short distance to the left from the location 53b which would represent a regular square array. As is shown in
In another example, the displaced vertex 53a and vertex 53c may be displaced by a random distance in a random direction, with the distance constrained to be no more than a predetermined range of distances. Thus, the vertex 53a may be constrained to be displaced to a position somewhere inside a circle 54 centered on the location 53b which the vertex 53a would have occupied in the regular square array and having a radius substantially equal to the predetermined maximum distance.
In some examples, the maximum displacement distance can be selected as a proportion of the distance between the vertices 53 in the regular square array. For example, the maximum displacement distance may be less than 0.5 times the distance between the vertices 53 in the regular square array. In one example, the displacement distance may be 0.1 times the distance between the vertices 53.
Both the distance and direction of displacement of a vertex may be randomly selected. In some examples, the direction of displacement may be randomly selected while the distance of displacement may be a fixed distance. In one example, this fixed distance of displacement may be approximately 0.1 times the spacing of the vertices.
In some examples, the distance of displacement may be varied in relation to the direction of displacement. In other examples, the amount of the variation may be varied based on the geometry of the array of vertices.
In some examples, the direction of displacement may be constrained so that the vertices can be displaced from positions corresponding to regular square shapes.
Although the lines appear as straight lines in the illustration, between vertices, the lines may have any of the sinusoidal shapes as discussed above relative to
Displacing the vertices of the electrode pattern away from positions in a regular geometric array may reduce the visibility of moire effects. Such moire effects may arise from interactions between the repeat length or cell size of an electrode pattern having vertices in a regular array and an element size of elements in a display visible through the touch position sensing panel. Such moire effects may arise from interactions between the repeat length or cell size of an electrode pattern and a cell size of an LCD display visible through the touch position sensing panel. Moire effects may produce a repeated pattern across the touch position sensing panel. Such repetitive interference patterns are readily perceived by the human eye.
As the deviation from regularity of a pattern of electrodes increases, the scattering of light increases. For example, Table 1 shows data from a Fast Fourier Transform (FFT) analysis of a mesh having a certain geometry. The FFT determines the number of angles formed by the reflection of light on a cell. As can be seen in the Table, as the randomness of the shape increases, a corresponding increase in angles occurs.
However, the randomization of the lines should be balanced by the increase of the amount of wiring in the electrode due. The increased amount of wiring may cause for less transmittance of light through the panel.
As is shown in
The locations of vertices 58c may then be selected by repeating the random selection process based on the locations of vertices 58b. In some examples, the random selection process may be carried out by randomly selecting a distance between each one of the vertices 58b and each of the vertices 58c. Each vertex 58c may be connected to one of the vertices 58b by a conductive metal line 56. Thus, the distances between each one of the vertices 58b and vertices 58c may be random.
This selection process may then be repeated in an iterative manner until all of the selected area of the exemplary electrode pattern 55 has been populated with vertices 58a to 58d interconnected by conductive lines 56.
As a result of this iterative process of selecting locations of the vertices 58a to 58d the mesh cells 57 making up the electrode pattern 55 have random shapes and sizes. In some examples, while the shapes comprising the mesh cells 57 may be random, the variations in the areas of the mesh cells 57 are minimized. For example, the variations in the areas of the mesh cells 57 from a mean mesh cell area of electrode pattern 55 are within 50%.
The randomly selected distances between vertices may be selected from a range having predetermined upper and lower limits. The predetermined upper and lower limits may be set at least in part based on the distances between the already located vertices.
In the illustrated example, the locations of the vertices and the conductive lines may be selected before the conductive lines are formed on the substrate.
In some examples, the conductive lines may be formed of copper with a width in the range approximately 1 μm to approximately 10 μm. In one example, the electrode pattern 10 is arranged so that no more than approximately 5% of the surface of the touch position-sensing panel may be covered by the conductive lines 56.
In
In other examples, different methods of randomly selecting the locations of the vertices may be used.
In some examples, the vertex locations determined by the iterative random selection of vertex locations may be checked to prevent conflicting vertex locations to occur. In some examples, when vertex locations conflict, the random selection process may be repeated until the vertex locations do not conflict. Examples of conflicting vertex locations include two or more vertices having one location, or vertex locations in which the conductive lines linking the vertices cross one another.
In some examples, the electrode pattern 55 may be iteratively defined by starting from one edge of a display or an electrode area and iteratively defining the positions of vertices until another edge of the display or electrode area is reached.
In
In some examples, the electrode patterns produced according to the illustrated examples of
As discussed regarding the example shown in
In some examples using mesh metal patterns for both electrode layers, the respective electrode patterns of the two electrode layers may be arranged so that the vertices of one of the electrode patterns are positioned at locations substantially corresponding to centers of mesh cells of the other electrode pattern. As a result of this arrangement of the two electrode patterns, the conductive lines of the two electrode patterns may be distributed more evenly across the touch position-sensing panel. In
For example, the pattern in
Arranging for vertices of one of the electrode patterns to be positioned at locations substantially corresponding to centers of mesh cells of the other electrode pattern may spread the conductive lines more evenly across the touch position sensing panel, and may reduce visible reductions in display brightness.
In some examples, the respective electrode patterns of the two electrode layers may be arranged so that where conductive lines in the two respective electrode patterns of the two electrode layers cross over one another, the conductive lines cross at an approximately 90° angle. In some examples, it may not be possible to arrange for some conductive lines to cross at a 90° angle and the conductive lines may be arranged to cross at as close to a 90° angle as is practicable. The conductive lines are arranged in curved shapes according to the examples shown in
Arranging for conductive lines in the two respective electrode patterns of the two electrode layers to cross over one another at, or close to, an approximately 90° angle may reduce mutual capacitance between the conductive lines. Arranging for conductive lines in the two respective electrode patterns of the two electrode layers to cross over one another at, or close to, an approximately 90° angle may prevent two closely spaced parallel or oblique lines to be perceived as a single thicker line. Arranging for conductive lines in the two respective electrode patterns of the two electrode layers to cross over one another at, or close to, an approximately 90° angle may spread the conductive lines more evenly across the touch position sensing panel, and may reduce visible reductions in display brightness.
In some examples, the respective electrode patterns of the two electrode layers may be arranged so that where conductive lines in the two respective electrode patterns of the two electrode layers cross over one another the phase and/or width of the conductive lines may be controlled according to the examples shown in
Reducing the width of the conductive lines in the respective electrode patterns in the two electrode layers where the conductive lines cross over may reduce visible reductions in display brightness at the interconnections. Such reductions in display brightness may be visible where constant width conductive lines cross over as there may be a concentration of conductive metal at the cross over point. Reducing the width of the sinusoidal conductive lines where the sinusoidal conductive lines cross over makes the distribution of the conductive metal across a touch position sensing panel more even, reducing the visibility of differences in display brightness.
The above examples refer to two electrode layers. The above examples could be extended to only one layer, or to three or more electrode layers. If three or more electrode layers are present, the vertices of the electrode patterns of the different layers may be arranged to spread the vertices approximately evenly across the touch position-sensing panel. Placing the vertices of some of the electrode patterns at locations corresponding to centers of mesh cells of other electrode patterns may not be effective for three or more electrode layers.
In some examples where a touch position sensing panel is intended to overlay a display having a set display cell size such as an LCD or LED display, the dimensions of the electrode pattern or patterns used may be selected, at least in part, based upon this set cell size of the display. This may allow visual interactions between the display and the touch position sensing panel to be minimized.
The illustrated examples described above relate to conductor elements and patterns of copper. However, other material may be used. For example, other metals suitable for use as wire pattern material.
The electrodes discussed above may also be incorporated into devices using a self-capacitance drive approach.
Various modifications may be made to the examples described in the foregoing, and any related examples may be applied in numerous applications, some of which have been described herein. It is intended by the following claims to claim any and all applications, modifications and variations that fall within the true scope of the present disclosure.
Claims
1. An apparatus comprising:
- a touch sensor comprising a first mesh of conductive material and a second mesh of conductive material, each of the meshes comprising a plurality of conductive lines, a first one of the conductive lines having a first portion and a second portion, the first portion being wider than the second portion, the first one of the conductive lines being coupled to a second one of the conductive lines, the second one of the conductive lines having a third portion and a fourth portion, the third portion being wider than the fourth portion; and
- one or more computer-readable non-transitory storage media coupled to the touch sensor and embodying logic that is configured when executed to control the touch sensor.
2. The apparatus of claim 1, wherein each of one or more of the conductive lines is a substantially straight line.
3. The apparatus of claim 1, wherein each of one or more of the conductive lines is substantially curved.
4. The apparatus of claim 1, wherein each of one or more of the conductive lines is substantially sinusoidal.
5. An apparatus comprising:
- a touch sensor comprising one or more meshes of conductive material, each of the meshes comprising a plurality of conductive lines, a first one of the conductive lines having a first portion and a second portion, the first portion being wider than the second portion; and
- one or more computer-readable non-transitory storage media coupled to the touch sensor and embodying logic that is configured when executed to control the touch sensor.
6. The apparatus of claim 5, wherein the one or more meshes of conductive material comprise a first mesh and a second mesh, the first mesh being disposed on a first surface of a substrate and the second mesh being disposed on a second surface of the substrate opposite the first surface.
7. The apparatus of claim 5, wherein the one or more meshes of conductive material comprise a first mesh and a second mesh, the first mesh being disposed on a surface of a first substrate and the second mesh being disposed on a surface of a second substrate.
8. The apparatus of claim 5, wherein each of one or more of the conductive lines is a substantially straight line.
9. The apparatus of claim 5, wherein each of one or more of the conductive lines is substantially curved.
10. The apparatus of claim 5, wherein each of one or more of the conductive lines is substantially sinusoidal.
11. The apparatus of claim 5, wherein the first one of the conductive lines is coupled to a second one of the conductive lines, the second one of the conductive lines having a third portion and a fourth portion, the third portion being wider than the fourth portion.
12. The apparatus of claim 5, wherein the first one of the conductive lines has a third portion connected to the first portion and the second portion, wherein a width of the third portion tapers from the width of the first portion to the width of the second portion.
13. A touch sensor comprising:
- one or more meshes of conductive material; and
- each of the meshes comprising a plurality of conductive lines, a first one of the conductive lines having a first portion and a second portion, the first portion being wider than the second portion.
14. The touch sensor of claim 13, wherein the one or more meshes of conductive material comprise a first mesh and a second mesh, the first mesh being disposed on a first surface of a substrate and the second mesh being disposed on a second surface of the substrate opposite the first surface.
15. The touch sensor of claim 13, wherein the one or more meshes of conductive material comprise a first mesh and a second mesh, the first mesh being disposed on a surface of a first substrate and the second mesh being disposed on a surface of a second substrate.
16. The touch sensor of claim 13, wherein each of one or more of the conductive lines is a substantially straight line.
17. The touch sensor of claim 13, wherein each of one or more of the conductive lines is substantially curved.
18. The touch sensor of claim 13, wherein each of one or more of the conductive lines is substantially sinusoidal.
19. The touch sensor of claim 13, wherein the first one of the conductive lines is coupled to a second one of the conductive lines, the second one of the conductive lines having a third portion and a fourth portion, the third portion being wider than the fourth portion.
20. The touch sensor of claim 13, wherein the first one of the conductive lines has a third portion connected to the first portion and the second portion, wherein a width of the third portion tapers from the width of the first portion to the width of the second portion.
Type: Application
Filed: Jan 11, 2012
Publication Date: Oct 18, 2012
Inventors: David Brent Guard (Southampton), Esat Yilmaz (Santa Cruz, CA), Tsung-Ching Wu (Saratoga, CA)
Application Number: 13/347,859
International Classification: G06F 3/044 (20060101); H01H 1/10 (20060101);