Patent ID: 8052320

Claim:
A backlight device, comprising: a white light source having a first light emission surface; a light transmitting member having a light incident surface on which light emitted from the first light emission surface of the white light source is incident, and a second light emission surface from which incident light is emitted; and a filter member that is arranged in a region through which light emitted from the white light source passes, the filter member absorbing or reflecting, at a predetermined ratio, light having a predetermined wavelength included in light emitted from the white light source, wherein the filter member is arranged so as to be tilted with respect to at least either the first light emission surface of the white light source or the second light emission surface of the light transmitting member, wherein the filter member is structured such that absorptance or reflectance of light having the predetermined wavelength varies as an incident angle of light varies, and wherein the filter member is structured such that a tilt angle at which the filter member is tilted with respect to at least either the first light emission surface of the white light source or the second light emission surface of the light transmitting member is adjustable.