Foldable display

A foldable display comprising:

• a housing unit including a hinge member, and a first housing and a second housing coupled via the hinge member;
• and
• a flexible display panel including a flexible display layer and a support substrate, wherein the support substrate is provided between the flexible display layer and the housing unit,
• by fixing a first portion of the support substrate to the first housing and fixing a second portion of the support substrate to the second housing, the flexible display panel is fixed to the housing unit,
• in a first state in which a surface of the first housing on a support substrate side and a surface of the second housing on the support substrate side are aligned on a same plane and the flexible display panel is in a non-bent state, the housing unit includes a planar portion being flat with respect to the same plane and at least one step portion including a step with respect to the same plane,
• the support substrate includes a third portion between the first portion and the second portion of the support substrate,
• the third portion of the support substrate includes, in the first state, a first region overlapping the at least one step portion and a second region overlapping the planar portion, and
• a first ratio of volume of openings of an opening group in the first region to volume of the first region in the first region of the support substrate is lower than a second ratio of volume of openings of an opening group in the second region to volume of the second region in the second region of the support substrate.