An ambulance cot loading and unloading device which utilizes an elongate guide track configured for mounting to a floor surface of a cargo area on the ambulance. The memory cell includes a stacked gate structure formed on the channel region, and first and second select gates formed on the channel regions and opposite sidewalls of the stacked gate structure. By positively using a parasitic capacitance between the counter electrode and the data line, the voltage level of the data line is changed before driving. Next, a filter is attached to the outside pane to cover the hole whereby the filter membrane is designed to allow the passage of air and inhibit the ingress of moisture. In some embodiments, the media display device attaches to the dental light. In addition, during exposure, the measured displacement is corrected based on the correction value in order to move and position the substrate to the optimal image forming location.