The invention concerns an electronic device (K) comprising solar cells (S1...Sn) which act as optical entry unit and, optionally, also as a voltage supply system (Uv). When separate solar cells (S1...Sn) are concealed from light, the potential (U1...Un) respectively produced by said cells decreases. In the electronic switching circuit (EC), binary control signals (D1...Dn) are derived from said potentials (U1...Un) to generate subsequent signals (ST1...ST3). The solar cells (S1...Sn) can be mounted, in particular, on electronic data media in the form of cards, such as smart cards. By sheltering some solar cells (S1...Sn), from light, selected data (D), for example, can be retrieved from a memory (M) and displayed on an output unit (A).