In a display device with optical sensors, a recognition processing portion performs recognition processing on a scan picture generated by optical sensors, and calculates a position. Embodiments provide for a wide range of operating powers with good energy efficiency at many power levels. The container body is formed with the developer discharge port. The retractable multi-use cardiac monitor further includes systems and methods for determining a length for the interelectrode distance that is optimum in terms of strength and fidelity of the detected ECG signals.