Electronic devices such as tablet terminals and multiple function mobile phones called smartphones, and the like operated by touching (touching with fingertips, etc.) images such as icons displayed on a screen are widely used. Such electronic devices are provided with a display screen formed of a display panel for displaying images, and a touch sensor overlapping this display screen.
Liquid crystal display panels and organic electroluminescence display panels are used as display panels used in such electronic devices. Electrostatic capacitance type touch sensors are mainly used as touch sensors provided overlapping the display panel. Electrostatic capacitance type touch sensors electrically detect changes in electrostatic capacitance by touch or by proximity of the body (fingertips, etc.) and determine whether or not there is a touch. A display device having an input function provided with a pixel region in which an organic light-emitting diode is formed above a substrate, and touch sensor electrodes provided above this pixel region, for example, is disclosed as a display device in which an electrostatic capacitance type touch sensor is added (for example, in U.S. Patent Application Publication 2015/0311477).
New uses for display panels such as liquid crystal display panels and organic electroluminescence display panels are being studied. For example, since it is possible to roll and fold display screens in display devices having flexibility, it is expected that an electronic device with an unconventional form can be provided. In display devices having flexibility, touch sensors are provided above the display surface so it is possible to realize display devices having input functions. However, since conventional touch sensors perform touch detection of plate-like display surfaces, touch input may be performed normally when a touch sensor is built into a display device having flexibility and spread out in a planar shape, but in a state in which a portion of the display screen is rolled and folded, there is a likelihood that touch detection will become unstable.