A liquid drop detector which may be fixed or attached by a simple operation, without machining, to a window glass, includes a light emitting element, a light receiving element and light guiding bodies wherein the light emitted by the light emitting element is introduced through a diffraction grating into a first light guiding body and after undergoing total internal reflection within the first light guiding body it is introduced through a silicon member, through an elongated light guiding body, through an additional silicon member, and into a windshield. After traveling within the windshield by total internal reflection, the light passes through a silicon member, reenters the elongated light guiding body, passes through another silicon member and enters a second light guiding body which guides it to a receiver. When rain drops adhere to the outside surface of the windshield at points corresponding to the total internal reflection points at the outer surface of the windshield, the light will leak out of the windshield. As a result of this, the amount of light received by the light receiving element is lessened, thereby providing for detection of the adhesion of rain drops based thereupon so as to output a signal for driving a device such as the windshield wiper.
A precipitation sensor has a prism bonded to a front windshield, a beam transmitter, and a beam receiver. The prism has an entry-side prism wall, a connection wall, and an exit-side prism wall. The entry-side prism wall of the prism parallelizes light transmitted from the beam transmitter by refracting them on a convex lens face. The parallelized light is reflected from a parabolic outer face of the prism wall toward the inner face of the windshield. The parallel beams reflected from the inner face of the front windshield are reflected from a parabolic outer face of the exit-side prism wall and then focused on the beam receiver through a convex lens face of the prism wall. The convex shapes of the lens faces form arcs, the centers of which are aligned with the beam transmitter and the beam receiver, respectively.
A method and a device for attaching a sensor device relative to a glass pane of a motor vehicle are described, a contact space being provided, which is sealed and which is provided with a partial vacuum.
The invention is a rain sensor including a transmitter and receiver formed by chips bonded onto a printed circuit board. Advantageous embodiments of the invention provide filtering of radiation guided to the receiver of the sensor. The sensor is provided with a barrier to suppress parasitic radiation.
A holographic sensor for recognizing moisture on a glass pane of a motor vehicle is provided, having a casing, a carrier layer, a diffractive element and an adhesive layer, the diffractive element being fixed, preferably glued, on the carrier layer. The diffractive element may be embodied as an embossed hologram.
A window fan assembly comprising a housing with openings therein for an air stream through the housing; at least one fan is mounted in the housing for generating the air stream through the openings of the housing; and a sensor connected to the housing, the sensor being disposed on the housing for detecting moisture particles associated with the air stream, upon the detection of a moisture particle of a predetermined size, the sensor causes an interruption of the air stream by stopping the fan operation.
