Plate-shaped fibre optic element made of transparent material and light module for a motor vehicle illumination device with such a fibre optic element

The invention relates to a plate-shaped light guide element (2) extending in a plane and made of a transparent material for deflecting light emitted by at least one light source (32). The light guide element (2) comprises a coupling-in section (6), totally reflecting external boundary surfaces, and a coupling-out section (12). Two mutually spaced, opposite surfaces (8, 10) of the light guide element form the totally reflecting boundary surfaces. The contour of the surfaces (8, 10) is defined by a curved curve section and a secant section. A curved side surface, which connects the surfaces (8, 10) along the curved curve section, forms the coupling-out section (12). A planar side surface, which connects the surfaces (8, 10) along the secant section, forms the coupling-in section (6). In order to enable efficient coupling-in of light from the light source (32), it is proposed that the coupling-in section (6) be associated with a reflection surface (18; 18') which is inclined at least in sections, which directs at least a portion of the light emitted by the at least one light source (32) for coupling-in into the light guide element (2) onto the coupling-in area (6).