NOVELTY - An impact resistant foil device (1) comprises optical layer (2) that is visible from front side (10) of the device, and electronics (3) for controlling and/or interfacing with optical layer, where optical layer and electronics are comprised in flexible foil structure (4) that has a pressure threshold ( sigma (critical)) and stretching threshold ( epsilon (critical)) below which thresholds ( sigma (critical), epsilon (critical)) the optical layer and electronics are not damaged; and backing structure (5) that is in mechanical contact with flexible foil structure on its backside opposite front side of device.    USE - As an impact resistant foil device (claimed), e.g. solar cell device.    ADVANTAGE - The device is provided with impact resistance without having to shield the front side of the device with a protective glass plate. The omission of a front glass plate can be beneficial e.g. for E-books and other display devices where a reflective front surface may be hindering a clear view of the display, especially outdoors, thus provides a more natural reading experience. The elastic response of the backing structure in compressed state is such that the flexible foil structure is prevented from overstretching e.g. beyond the stretching threshold for damage. In this way the device can be protected from slow impressions of the flexible foil where a viscous response may play a minor role.    DETAILED DESCRIPTION - An impact resistant foil device (1) comprises an optical layer (2) that is visible from a front side (10) of the device; and electronics (3) for controlling and/or interfacing with the optical layer, where the optical layer and electronics are comprised in a flexible foil structure (4) that has a pressure threshold ( sigma (critical)) and a stretching threshold ( epsilon (critical)) below which thresholds ( sigma (critical), epsilon (critical)) the optical layer and electronics are not damaged; and a backing structure (5) that is in mechanical contact with the flexible foil structure on its backside opposite the front side of the device, where the backing structure comprises a deformable material having a viscous response in a critical range, which critical range is defined for a given front impact event by the pressure threshold ( sigma (critical)) and the stretching threshold ( epsilon (critical)), where the critical range chosen between an upper threshold which allows the backing structure to deform so as to keep a pressure exerted on the flexible foil structure as a result of the impact (9) lower than the pressure threshold ( sigma (critical)), and a lower threshold which keeps the deformation of the backing structure within a maximum deformation range so as to prevent an overstretching of flexible foil structure beyond the stretching threshold ( epsilon (critical)), thus allowing a majority portion of an energy of the impact to dissipate by the viscous response of the backing structure. An INDEPENDENT CLAIM is included for providing a device that is resistant to a given front side impact, involving providing an optical layer and electronics for controlling and/or interfacing with the optical layer, where the optical layer and electronics are comprised in a flexible foil structure; determining a pressure threshold ( sigma (critical)) and a stretching threshold ( epsilon (critical)) of the flexible foil structure, below which thresholds ( sigma (critical), epsilon (critical)) the optical layer and electronics are not damaged; and selecting a backing structure and bringing the backing structure in mechanical contact with the flexible foil structure on a backside opposite the front side impact.    DESCRIPTION OF DRAWING(S) - The figure shows stress-strain curves of a backing structure material at different strain rates.    Impact resistant foil device (1)    Optical layer (2)    Electronics (3)    Flexible foil structure (4)    Backing structure (5)    Deformable material (5a)    Micro-cells/pockets (5b)    Back layer (8)    Front side (10)