OPTICAL POINTING DEVICE, METHOD FOR ARRANGING LIGHT EMITTING DIODE IN THE SAME, AND METHOD FOR SELECTING OPTICAL PARAMETER

摘要

PROBLEM TO BE SOLVED: To improve accuracy and to eliminate the harmful influence of noise and unstableness of a user's hand by arranging a light emitting diode mounted on a substrate behind a lens which is at a distance equal to the focal length of a lens, and arranging a light diffuser nearby the lens. SOLUTION: Four LEDs 21 with a radius (r) are arranged on the focal plane 22 of a lens 20 at equal intervals along a circuit having a radius R. The light beam 24 from a basic optical mechanism deviates by an angle Ao from the axis 25. The angle Ao does not depend upon the direction of the light emitted by an LED 21 and depends upon on the radial position R of the LED 21. Further, light from a different part of the LED 21 exits from a different radial position. An angle A of divergence can be made narrower than the width of a desired beam profile by using the LED 21 with the small diameter. Then a final beam profile is generated by an ordinary light diffuser 25. Therefore, each final beam profile becomes nearly equal.