Patent ID: 8388160

Claim:
A backlight device comprising: a light source; a diffusion plate that diffuses light from the light source; and a support member that is disposed below the diffusion plate and includes a support surface for supporting the diffusion plate, wherein the diffusion plate includes: a light incidence surface on which light from the light source becomes incident; a light output surface that outputs incident light to a side of a display panel; and an upper surface and a lower surface that extend in a direction intersecting an extending direction of the light incidence surface and the light output surface, the support surface of the support member is in contact with at least part of the lower surface of the diffusion plate, and in a state where the diffusion plate is not warped, a center of gravity of the diffusion plate is disposed on a side opposite to the display panel with respect to a position of contact between the lower surface of the diffusion plate and the support surface of the support member.