| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain a photoelectric sensor for detecting rain fall on the outer surface of a transparent glass of an automobile in which the optical characteristics are enhanced while decreasing the number of optical components and shortening the structural length of the sensor. SOLUTION: A beam guide 1 is provided, on the rear surface 7 side thereof, with recesses 8, 81 for receiving a light transmitter 13 and a light receiver 14. A light emitted from the light transmitter is passed through a light beam incident face 9 at one recess to the beam guide and a diverging luminous flux therefrom is reflected within the mirror range of an associated side face 5 to produce a parallel luminous flux. The parallel luminous flux reaches a glass 4 at an angle of about 45 deg. and the luminous flux reflected on the outer surface 41 of the glass is reflected again within the mirror range 62 of the outer side face 6 and converged before being fed to the light receiver through an exit face 10 associated with the other recess by means of two opposite side faces 5, 6 of the beam guide being mirrored at least partially and directed toward respective recesses.</p> |
