Patent ID: 8300076

Claim:
A line head, comprising: a substrate which transmits a light beam; a luminous element group which includes a plurality of luminous elements which are on the substrate; an imaging lens which is provided corresponding to the luminous element group; and a light shielding member which is disposed so that its one surface is opposed to a surface of the substrate, the surface being different from the surface on which the luminous element group is provided, and that its other surface is opposed to the imaging lens, and which includes a light guiding hole corresponding to the luminous element group, wherein a thickness of the substrate and an index of refraction of the substrate are set so that a light beam emitted from an outer-most element, which is a luminous element which is one of the luminous elements belonging to the luminous element group and which is located at the shortest distance to a neighboring aperture in the one surface of the light guiding hole which corresponds to a next luminous element group which is next to the luminous element group, toward the neighboring aperture is totally reflected by the surface, which is opposed to the light shielding member, of the substrate.