A display panel includes a first substrate, a shading module, a second substrate, optical sensors, and a parallel-to-serial converter. The shading module is disposed on the first substrate. The second substrate is disposed corresponding to the first substrate. The optical sensors are disposed on the second substrate, and are disposed corresponding to the shading module. The optical sensors are configured to output sensing signals according to an offset amount between the optical sensors and the shading module. One of the optical sensors includes a first switch and a second switch, in which the first switch and the second switch are coupled in cascade. The parallel-to-serial converter is configured to generate the serial signal according to the sensing signals.