| 摘要 |
PROBLEM TO BE SOLVED: To provide an electronic underlay capable of avoiding detection of an unwanted part such as a little finger or a root part of the little finger of a hand holding a writing instrument such as a pen, when writing a note or the like in a sheet with the writing instrument.SOLUTION: An electronic underlay A is used as laid under a sheet configured to be written in with a writing instrument. The electronic underlay comprises: a sheet-like optical waveguide W in which a grid-like core 2 is interposingly held by a sheet-like underclad layer 1 and an overclad layer 3; a light-emitting device 4 connected to one end face of the core 2; a light receiving device 5 connected to the other end face of the core 2; and storage means for storing inputted notes as electronic data. Elasticity modulus of the core 2 is set larger than elasticity modulus of the underclad layer 1 or elasticity modulus of the overclad layer 3. Accordingly, when a surface of the optical waveguide W is pressed, a deformation ratio of a cross section of the core 2 in the pressed direction is smaller than a deformation ratio of a cross section of the overclad layer 3 or the underclad layer 1. |
