Abstract: A display device including: scan lines including first and second scan lines; pixels connected to the scan lines; photo sensors connected to some of the scan lines, the photo sensors including a first photo sensor connected to the first scan line and a readout line, and a second photo sensor connected to the second scan line and the readout line; a scan driver to provide scan signals to the scan lines; and a readout circuit to receive, through the readout line, detection signals which are outputted from the photo sensors in response to the scan signals, wherein, while the scan signals are provided to the first and second scan lines, the readout circuit samples a detection signal of one of the first photo sensor and the second photo sensor without sampling a detection signal of the other one of the first photo sensor and the second photo sensor.

Abstract: A paper feeding device to sense various sizes of paper according to a sensing voltage output from a sensor and an image forming apparatus having the same includes a body to receive paper in which an image is printed thereon. The image forming apparatus further includes a paper feeding device to feed paper into the body. The paper feeding device includes a paper tray in which paper is loaded, and paper guides that are slidably installed to the paper tray to guide left and right ends of paper loaded in the paper tray in a paper feeding direction. A light reflector is installed to be moved in linkage with the paper guides and includes a stepped reflection surface. A sensor emits light to the light reflector and receives the light reflected by the light reflector to determine the sizes of paper.