Abstract: An optical droplet sensor can include a light emitter, a light receiver and a light guide, and can be adhered onto an inner surface of a windshield via a light transmissive adhesive layer. The light guide can include a light entry surface and a light exit surface formed of respective convex-shaped arbitrary curved surfaces, a light entry/exit surface formed of a flat plane, and a reflecting surface that can be made of a metal film. The light emitted from the light emitter is given an optimized light distribution at the light entry surface and introduced into the light guide. The light is then reflected from the metal film-applied reflecting surface toward an outer surface of the windshield. The light totally reflected at the outer surface returns to the light exit surface and is given an optimized light distribution at the light exit surface. The light is then externally transmitted/released from the light guide and collected on a light-receiving surface of the light receiver.

Abstract: An optical droplet sensor can include a light emitter, a light receiver and a light guide, and can be adhered onto an inner surface of a windshield via a light transmissive adhesive layer. The light guide can include a light entry surface and a light exit surface formed of respective convex-shaped arbitrary curved surfaces, a light entry/exit surface formed of a flat plane, and a reflecting surface that can be made of a metal film. The light emitted from the light emitter is given an optimized light distribution at the light entry surface and introduced into the light guide. The light is then reflected from the metal film-applied reflecting surface toward an outer surface of the windshield. The light totally reflected at the outer surface returns to the light exit surface and is given an optimized light distribution at the light exit surface. The light is then externally transmitted/released from the light guide and collected on a light-receiving surface of the light receiver.

Abstract: In an optical coordinate input apparatus, the light emitting elements 3a and the light receiving elements 3b of a surface-mounted type constituting the photocouplers 3 are used and mounted on the substrate 2 in close contact with the substrate 2 and the photocouplers 3 arranged on the rear side 2d are displaced from the photocouplers 3 arranged on the front side 2c by half a pitch. Therefore, the lines 3c of action of the photocouplers 3 can be made close to the substrate and the resolution can be improved to twofold while there is not produced such a difference of the detection position that will cause practical inconvenience.

Abstract: In an oscillation control apparatus for an ultrasonic oscillator, an FET circuit is connected to an oscillation circuit for varying a resistant value of a resistor unit of the oscillation circuit, which determines a free-running frequency thereof. A phase-difference detecting circuit is provided for detecting a relative phase difference between voltage and current in the ultrasonic oscillator. A threshold discrimination circuit outputs a signal when the phase difference inputted from the phase-difference detecting circuit exceeds at least a predetermined value. A pump circuit integrates the signal from the threshold discrimination circuit. A resistant value of the FET circuit varies when an output signal from the pump circuit exceeds a predetermined value.