Substrate with transparent electrodes and devices incorporating it
The substrate with electrodes is formed of a transparent material onto which is deposited a film ( 1 ) of a transparent conductive material of thickness e 1 and of refractive index n 1 , said film being structured to form a set of electrodes ( 1 a ) whose contours ( 8 ) delimit insulating spaces ( 3 ), wherein the insulating spaces ( 3 ) are filled with a transparent dielectric material of thickness e 2 and of refractive index n 2 so that the respective thicknesses of the conductive material and the dielectric material are inversely proportional to the values of the refractive indices of said materials and said dielectric material forms neither depressions nor beads at the contour ( 8 ) of the electrodes. A hardcoating layer ( 7 ) may be disposed between the substrate ( 5 ) and the electrodes and a protective film ( 9 ) added. The substrate with electrodes is obtained by UV irradiation through a single mask.
1. A substrate with transparent electrodes and formed of a transparent material onto which is deposited a film of a transparent conductive material of thickness e1 and of refractive index n1, wherein said film is structured to form a set of electrodes whose contours delimit insulating spaces, the electrodes having contact areas close to an edge of the substrate for connecting to an electronic device, wherein the substrate is characterized in that the insulating spaces are filled with a transparent dielectric material of predetermined thickness e2 and of refractive index n2 so that the transparent dielectric material does not cover the electrodes, and wherein thickness e2 is a function of refractive index n2 so that a light path incident upon the substrate is unmodified at any incidence of observation thereby making a contour of the electrodes invisible to a user observing the substrate.
2. A substrate according to claim 1 , wherein said substrate is made from plastic material, further comprising:
an intermediate layer of uniform thickness of an additional hard, transparent, non-conductive material disposed between the substrate and the electrodes, wherein the intermediate layer resists degradation in the event of increases in temperature.
3. A substrate according to claim 2 , wherein the hard intermediate layer consists of a resin incorporating SiO 2 having at least a thickness of 20 μm.
4. A substrate according to claim 2 , wherein the substrate is made from polymethylmethacrylate or polycarbonate.
5. A substrate according to claim 1 , wherein the electrodes and the dielectric material filling the insulating spaces are further covered with a protective film.
6. A substrate according to claim 1 , wherein the transparent conductive material forming the electrodes is a transparent conductive oxide selected from indium and tin oxide (ITO), In 2 O 3 and SnO 2 , doped with Sb.
7. A substrate according to claim 1 , wherein the dielectric material filling the spaces between the electrodes is a non-conductive transparent oxide selected from TiO 2 and SiO 2 .
8. A substrate according to claim 1 , wherein the thickness e1 of the transparent conductive material is from 50 to 100 nm.
9. A substrate according to claim 1 , wherein the substrate constitutes a capacitive or resistive touch-sensitive screen for controlling the associated electronic device.
10. A substrate according to claim 1 , wherein the substrate constitutes at least one closure plate of a liquid crystal display cell or a photovoltaic cell associated with the electronic device.
11. A substrate according to claim 5 , wherein the protective film has anti-reflection properties.
12. A substrate according to claim 1 , wherein the thickness e1 of the transparent conductive material is from 65 to 75 nm.
13. A substrate with transparent electrodes and formed of a transparent material onto which is deposited a film of a transparent conductive material of thickness e1 and of refractive index n1, wherein said film is structured to form a set of electrodes whose contours delimit insulating spaces, the electrodes having contact areas close to an edge of the substrate for connecting to an electronic device, wherein the substrate is characterized in that the insulating spaces are filled with a transparent dielectric material of thickness e2 and of refractive index n2 so that the respective thicknesses of the conductive material and the dielectric material are inversely proportional to the values of the refractive indices of said materials and said dielectric material forms neither depressions nor beads at the contour of the electrodes, wherein the electrodes and the dielectric material filling the insulating spaces are further covered with a protective film that has anti-reflection properties, and wherein the protective film does not cover the contact areas of the electrodes.
14. A substrate with transparent electrodes and formed of a transparent material onto which is deposited a film of a transparent conductive material of thickness e1 and of refractive index n1, wherein said film is structured to form a set of electrodes whose contours delimit insulating spaces, the electrodes having contact areas close to an edge of the substrate for connecting to an electronic device, wherein the substrate is characterized in that the insulating spaces are filled with a transparent dielectric material of predetermined thickness e2 and of refractive index n2, and wherein thickness e2 is a function of refractive index n2 so that a light path incident upon the substrate is unmodified at any incidence of observation thereby making a contour of the electrodes invisible to a user observing the substrate, wherein the electrodes and the dielectric material filling the insulating spaces are further covered with a protective film that does not cover the contact areas of the electrodes.