1. Field of the Invention
The present invention relates to a display device with a touch panel, and more particularly, to a display device with a touch panel which includes a capacitance coupling type touch panel.
2. Description of the Related Art
Major systems adopted by conventional touch panels include a system of detecting an optical change and a system of detecting a change in electric characteristic. As systems of detecting a change in electric characteristic, a capacitance coupling system is known (see, for example, JP 2008-65748 A and JP 2009-015489 A).
FIGS. 9 to 11 illustrate a conventional capacitance coupling type touch panel. FIG. 9 is a plan diagram illustrating an electrode pattern, FIG. 10 is a sectional diagram illustrating a sectional structure cut on the line X-X of FIG. 9, and FIG. 11 is a sectional diagram illustrating a sectional structure cut on the line XI-XI of FIG. 9.
As illustrated in FIGS. 9 to 11, the conventional capacitance coupling type touch panel includes a plurality of electrodes 1X extending in a first direction (e.g., X direction) and being disposed in parallel in a second direction (e.g., Y direction) intersecting the first direction, and a plurality of electrodes 2Y intersecting the electrodes 1X, extending in the second direction, and being disposed in parallel in the first direction. The plurality of electrodes 2Y are disposed on a substrate 11 to be covered with an insulating film 12 formed thereon. The plurality of electrodes 1X are disposed on the insulating film 12 to be covered with a protective film 13 formed thereon. The electrodes 1X and 2Y are made of transparent conductive materials such as indium tin oxides (ITOs).
In the conventional capacitance coupling type touch panel, as illustrated in FIGS. 9 to 11, the plurality of electrodes 1X and the plurality of electrodes 2Y are formed on different conductive layers (upper and lower layers) via the insulating film 12. In the case of this electrode structure, distortion occurs in the protective film 13 formed on the insulating film 12 and the electrodes 1X of the upper layer because of the electrode 1X of the upper layer, and optical path lengths are different between the upper and lower layers with respect to a reflected light. Thus, a color difference is generated between the upper electrodes 1X and the lower electrodes 2Y, making electrode patterns of the electrodes 1X and 2Y visible. Such visible electrode patterns cause deterioration of optical characteristics and reduction in characteristics of a display device incorporating the touch panel. Thus, countermeasures are necessary.