Composite substrate that prevents flexible print circuit board from peeling off from drive interconnect substrate

A composite substrate comprising:

• a first substrate having a surface;
• a second substrate having a first surface and a second surface opposite to the first surface in a thickness direction, the second substrate extending in a longitudinal direction perpendicular to the thickness direction, the second substrate having a first end and a second end in the longitudinal direction, the second surface facing the surface of the first substrate with a gap therebetween, and the second substrate being provided with a driver circuit on the first surface;
• a flexible print circuit board having a portion bonded to a position on the first surface between the first end and the driver circuit in the longitudinal direction, a bonding region being defined on the first surface as such a region to which the portion of the flexible print circuit board is bonded;
• and
• a support member provided between the surface of the first substrate and the second surface of the second substrate, the support member overlapping an entire part of the bonding region on the first surface, as viewed in the thickness direction.