US Patent 7242029 Light emitting device

A light emitting element array is made with large light emitting elements and small light emitting elements are arranged on a substrate in a matrix-like form. The large light emitting element has the luminescent area of about 1 mm square. There is a clearance N1 of about 0.5 mm between the large light emitting elements. The small light emitting element has the luminescent area of about 0.5 mm square, and each small light emitting element is disposed at a position corresponding to each clearance N1 in the scanning direction. Because the large light emitting elements and the small light emitting elements do not overlap each other in the scanning direction, even if the light emitting element array comes close to a thermosensitive recording paper, there becomes no uneven distribution of light quantity of the light emitting element array in the scanning direction.