Touch screen sensor and patterned substrate having overlaid micropatterns with low visibility
Presently described are articles such as antennas, EMI shields, and touch screen sensors as well as patterned substrates having overlaid micropatterns with low visibility. Also described are methods of determining the visibility of a patterned substrate. In one embodiment, a patterned substrate is described comprising a visible light transparent substrate; and at least two overlaid electrically conductive mesh micropatterns, wherein each mesh has a repeating cell geometry and the combination of overlaid micropatterns has a spatial contrast threshold at a distance of 30000 units of greater than −35 decibels.
1. A touch screen sensor, comprising: a visible light transparent substrate; and
at least two overlaid conductive mesh micropatterns with two dimensional contiguous meshes comprising:
a first conductive mesh micropattern comprising linear traces defining a first open mesh of a repeating cell geometry disposed on or in the visible light transparent substrate, and
a second conductive mesh micropattern comprising linear traces defining a second open mesh of a repeating cell geometry electrically isolated from the first conductive mesh micropattern oriented at a bias angle such that at least a portion of the linear traces of the second conductive mesh micropattern are non-parallel to the linear traces of the first conductive mesh micropattern; and
wherein the second conductive mesh micropattern overlays the first conductive mesh micropattern such that at least a portion of the second conductive mesh micropattern has a different cell geometry from the cell geometry of the first conductive mesh micropattern; or
at least a portion of the second conductive mesh micropattern has a different cell dimension from the cell dimension of the first conductive mesh micropattern; or a combination thereof.
2. The touch screen sensor of claim 1 wherein at least a portion of the linear traces of the second conductive micropattern are non-parallel to the linear traces of first conductive micropattern.
3. The touch screen sensor of claim 1 wherein at least a portion of the second conductive micropattern has a different cell dimension from the cell dimension of the first conductive micropattern.
4. The touch screen sensor of claim 1 wherein the first and second conductive micropatterns have the same cell geometry.
5. The touch screen sensor of claim 1 wherein the first and second conductive micropatterns each comprise a regular cell geometry.
6. The touch screen sensor of claim 1 wherein the first and second conductive micropatterns comprise a hexagonal cell geometry.
7. The touch screen sensor of claim 4 wherein the second micropattern is orientated at a bias angle ranging from 15 degrees to 40 degrees relative to the first micropattern.
8. The touch screen sensor of claim 1 wherein the linear traces have a line width of less than 5 microns.
9. The touch screen sensor of claim 1 wherein the cell geometry of the first and second micropatterns has an average cell width of no greater than 500 microns.
10. The touch screen sensor of claim 1 wherein the first micropattern has a regular hexagonal cell geometry and the second micropattern has a regular hexagonal cell geometry;
a ratio of the cell dimension of the first micropattern to the cell dimension of the second micropattern is between 1.2 to 3; and
a bias angle between the first micropattern and the second micropattern is between 10 and 45 degrees.
11. The touch screen sensor of claim 4 wherein at least a portion of the linear traces of the second conductive micropattern are non-parallel to the linear traces of the first conductive micropattern and there is a bias angle between the first conductive micropattern and second conductive micropattern of between 0.1 and 0.9 times a repeat angle.
12. The touch screen sensor of claim 4 wherein the cell dimension of the first conductive micropattern is between 1.1 and 6 times the cell dimension of the second conductive micropattern, and there is a bias angle between the patterns of between 0.1 and 0.9 times a repeat angle.
13. The touch screen sensor of claim 1 wherein the combination of electrically conductive mesh micropatterns has a contrast threshold at a distance of 30000 foveal detection model distance units of greater than −35 decibels.
14. The touch screen sensor of claim 13 wherein the mesh micropatterns have a pattern density of less than 20%.
15. The touch screen sensor of claim 13 wherein the cell geometry of the first and second mesh micropatterns has an average cell width of no greater than 500 microns.
16. An electrically conductive article comprising: a visible light transparent substrate; and at least two overlaid conductive mesh micropatterns with two dimensional contiguous meshes comprising: a first conductive mesh micropattern comprising linear traces defining a first open mesh of a repeating cell geometry disposed on or in the visible light transparent substrate, and
a second conductive mesh micropattern comprising linear traces defining a second open mesh of a repeating cell geometry electrically isolated from the first conductive mesh micropattern; and
wherein the second conductive mesh micropattern overlays the first conductive mesh micropattern such that
i) at least a portion of the linear traces of the second conductive mesh micropattern are non-parallel to the linear traces of first conductive mesh micropattern and oriented at a bias angle; and
ii) at least a portion of the second conductive mesh micropattern has a different cell geometry than the first conductive mesh micropattern; or iii) at least a portion of the second conductive mesh micropattern has a different cell dimension than the first conductive mesh micropattern; or a combination thereof.
17. The article of claim 16 wherein the first or second micropattern functions as an antenna or electromagnetic interference (EMI) shield.