Linear light source with increased light efficiency and uniform exposure, and image sensor using the linear light source

摘要

A linear light source is provided in which surface mounting type LED chips are arranged linearly on a circuit board. Each LED chip is given a light condensing function. The ratio between the arrangement interval of the adjacent LED chips and the distance from the LED chip to an exposure surface is determined according to the directivity characteristic of each LED chip and the following equation:where L(theta) is exposure at an angle theta, and theta is an angle with respect to a perpendicular to the exposure surface from a LED chip.