According to one embodiment, a display device includes a display part, a plurality of sensor electrodes and a controller. The display part is configured to display an image. The plurality of sensor electrodes are arranged to surround the display part. The controller is electrically connected to the sensor electrodes, and is configured to detect an object close to or contacting the sensor electrodes. The controller drives at least one of the sensor electrodes as a detection electrode and drives at least one of the sensor electrodes as a drive electrode.

[Problem] To synchronize timings of transmitting and receiving a pulse signal (1 PPS signal) at a constant interval between communication apparatuses even in a case where an optical fiber connecting the communication apparatuses fluctuates in an optical characteristic and an optical fiber length. [Solution] The time synchronization system 20 transmits and receives a pulse signal at a constant interval between a local apparatus L (apparatus L) and a remote apparatus R (apparatus R) connected through the two-core bidirectional optical fibers F1 and F2 to synchronize time. A propagation delay amount τ1 in the fiber F1 is calculated, from a proportional relationship between T1 and T2 and a proportional relationship of τud and τ1, where T1 represents a propagation delay time difference between a pulse signals P1 and P4 of an identical wavelength λ.sub.1 returned after transmitting a pulse signal P1 of wavelength λ.sub.1 and a pulse signal P2 of wavelength λ.sub.2 different from λ.sub.1 to the remote apparatus R, T2 represents a propagation delay time difference between the pulse signal P1 of wavelength λ.sub.1 and a pulse signal P3 of wavelength λ.sub.2, and τud represents the round-trip delay time between the apparatuses L and R. The pulse signals P1 and P2 are transmitted with a time difference td corresponding to a difference between the current and last calculated propagation delay amounts τ1 being set so that the difference is zero.

[Problem] To synchronize timings of transmitting and receiving a pulse signal (1 PPS signal) at a constant interval between communication apparatuses even in a case where an optical fiber connecting the communication apparatuses fluctuates in an optical characteristic and an optical fiber length.

[Solution] The time synchronization system 20 transmits and receives a pulse signal at a constant interval between a local apparatus L (apparatus L) and a remote apparatus R (apparatus R) connected through the two-core bidirectional optical fibers F1 and F2 to synchronize time. A propagation delay amount 1 in the fiber F1 is calculated, from a proportional relationship between T1 and T2 and a proportional relationship of ud and 1, where T1 represents a propagation delay time difference between a pulse signals P1 and P4 of an identical wavelength .sub.1 returned after transmitting a pulse signal P1 of wavelength .sub.1 and a pulse signal P2 of wavelength .sub.2 different from .sub.1 to the remote apparatus R, T2 represents a propagation delay time difference between the pulse signal P1 of wavelength .sub.1 and a pulse signal P3 of wavelength .sub.2, and ud represents the round-trip delay time between the apparatuses L and R. The pulse signals P1 and P2 are transmitted with a time difference td corresponding to a difference between the current and last calculated propagation delay amounts 1 being set so that the difference is zero.

According to one embodiment, a display device includes a display part, a plurality of sensor electrodes and a controller. The display part is configured to display an image. The plurality of sensor electrodes are arranged to surround the display part. The controller is electrically connected to the sensor electrodes, and is configured to detect an object close to or contacting the sensor electrodes. The controller drives at least one of the sensor electrodes as a detection electrode and drives at least one of the sensor electrodes as a drive electrode.