Polarization conversion element

A polarization conversion element comprising:

• a first substrate comprising a first transparent substrate comprising a first inner surface and a first outer surface, a first wiring and a second wiring disposed on the first inner surface, a transparent planar electrode being in contact with the first wiring and the second wiring, a first insulating film covering the planar electrode, a control electrode disposed on the first insulating film and comprising first strip electrodes extending in a same direction, and a first alignment film covering the control electrode;
• a second substrate comprising a second transparent substrate comprising a second inner surface and a second outer surface, and a second alignment film disposed on the second inner surface;
• and
• a liquid crystal layer disposed between the first substrate and the second substrate, wherein
• an alignment treatment direction of the first alignment film and an alignment treatment direction of the second alignment film are parallel to each other and cross an extension direction of the first strip electrodes,
• the control electrode overlaps the planar electrode in plan view,
• an applied voltage of the first wiring is configured to be higher than an applied voltage of the second wiring, and
• the planar electrode is configured to have a voltage gradient.