DEVICE FOR DETECTING THE MIXING RATIO OF PETROL AND AN ALCOHOL OR THE LIKE

摘要

A device for detecting the mixing ratio of petrol and alcohol or the like comprising; a flint glass (3), the outer surface of which is in direct contact with a mixing liquid of petrol and alcohol; a light emitting diode (5) placed to position within the flint glass so that the light beams therefrom are incident on a boundary between the glass and the mixing liquid, the light beams incident on the boundary at less than a critical angle being totally refracted, while the light beams incident on the boundary at more than a critical angle being totally reflected, the critical angle depending on a mixing degree of said liquid; a photo diode (6) placed in coplanar relationship with the light emitting diode to receive the light beams reflected at the boundary to generate an output in accordance with the light beams received; and a width of the photo diode and a distance between the diodes being determined such that the photo diode receives the light beams merely ranging from one reflected at a critical angle with a mixing ratio of the liquid as 100:0 to other reflected at a critical angle with a mixing ratio of the liquid as 0:100.