Patent ID: 8643796

Claim:
A liquid crystal display device having a plurality of pixels, comprising: a first substrate including: an insulating substrate, a plurality of signal lines arranged above the insulating substrate and extending in a first direction, a first insulating film covering the signal lines, a plurality of capacitance lines arranged on the first insulating film and extending in a second direction crossing the first direction, each capacitance line including a slit formed above a portion of a respective signal line and extending in the first direction, a second insulating film covering the capacitance lines, and a plurality of pixel electrodes arranged on the second insulating film so as to face the capacitance lines, the respective pixel electrodes including a plurality of slits, and a second substrate opposing to the first substrate; a liquid crystal layer held between the first and second substrates and including liquid crystal molecules; and a detection circuit to detect change of electrostatic capacitance between the signal lines and the capacitance lines; wherein the capacitance lines include a common electrode arranged in common to the plurality of pixels, and the liquid crystal molecules are switched mainly using a lateral electric field between the common electrode and the pixel electrode; and the detection circuit writes a detection signal into the plurality of capacitance lines simultaneously by grouping the capacitance lines of adjacent rows of pixels during a detection period successive to an image signal write-in period to write the image signal into the pixel electrode, and thereby detects the change of the electrostatic capacitance between the signal lines and the capacitance lines.