Patent ID: 8896576

Claim:
A touch panel comprising: an infrared light transmitting material through which infrared light is transmitted and which has a surface being used as a touch surface, the touch surface being touched by a detection subject; infrared light sensors including a plurality of infrared light receiving elements provided below a touch region of the infrared light transmitting material, the touch region being touched by the detection subject; and a plurality of infrared light sources provided in an outside of the touch region of the infrared light transmitting material, the plurality of infrared light sources being configured to emit infrared light along said surface of the infrared light transmitting material such that an entire circumference of the detection subject touching the touch surface is irradiated with the infrared light, the touch panel detecting a position touched by the detection subject in such a manner that at least one of the infrared light sensors receives, among infrared light emitted by the infrared light sources along said surface of the infrared light transmitting material, infrared light which is reflected by the detection subject and is transmitted through the infrared light transmitting material, wherein: a light path changing section is provided in the outside of the touch region, the light path changing section changing a light path of infrared light emitted by the infrared light sources so that the light path becomes in parallel with said surface of the infrared light transmitting material, wherein: the infrared light transmitting material includes an extension section which is extended from the infrared light transmitting material and is provided in the outside of the touch region; the extension section has a surface which is on the side of the touch surface, the surface being provided with the light path changing section having an inclined surface which is inclined with respect to the touch surface; the infrared light is emitted to the inclined surface; and the following formula (1) is satisfied: θ=arcsin [ n ·sin {arcsin( k )−θ 0 }] (1), where n denotes a relative refractive index of the infrared light transmitting material with respect to an absolute refractive index of air, θ 0 denotes an angle by which the inclined surface is inclined with respect to the touch surface, θ denotes an angle of incidence of infrared light with respect to the inclined surface, and k is 0.975 or greater and not greater than 1.