Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Patent
1997-11-05
2000-05-16
Allen, Stephone B.
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
25022725, 250577, 340602, 318483, 318DIG2, G01N 2117
Patent
active
060640596
DESCRIPTION:
BRIEF SUMMARY
STATE OF THE TECHNOLOGY
The invention relates to an arrangement for detecting moisture conditions on a pane, particularly a windshield of a motor vehicle, the arrangement having a radiation transmitting device which is supported on a circuit board and has at least one transmitter, having a beam guide which can be coupled to the pane and is oriented essentially parallel to the circuit board and is provided with a beam entry surface to receive the emitted radiation and with a beam exit surface to emit the radiation, and having a radiation receiving device which receives the exiting radiation and is also supported on the circuit board and which has at least one receiver.
An arrangement of this type is specified as being known in DE 44 06 398 A1. In this known arrangement in the form of a rain sensor, which can be attached on the windshield of a motor vehicle, a circuit board is arranged parallel to a flat longitudinal plane of a transparent light guide by means of which light is coupled into and out of the pane; the circuit board is connected to a second board by means of elastic connecting lines. Seated in holders, a transmitter and a receiver are connected on the circuit board, which transmitter and receiver project with their light-emitting or light-receiving element approximately into a center plane of the light guide, which is disposed parallel to the plane of the circuit board, in such a way that the optical axes of the transmitter and of the receiver are also substantially disposed in the center plane of the light guide so as to couple the light into and out of the light guide. The arrangement of this type of the transmitter and receiver requires a relatively large structural space and additional assembly steps during production, during which process attention must be paid to a precise positioning of the transmitter and of the receiver with respect to the light guide or radiation guide.
SUMMARY AND ADVANTAGES OF THE INVENTION
It is the object of the invention to make available an arrangement of the type specified at the outset which is simpler to produce and results in a design which saves more space.
This object is accomplished according to the invention by an arranged for detection moisture conditions on a pane, particulary the windshield of a motor vehicle; of the type described above wherein the beam entry surface and/or the beam exit surface is/are arranged on the parallel side of the radiation guide facing the circuit board, and that the optical axis of the transmitter or of the receiver is oriented to be perpendicular to the beam entry surface or the beam exit surface and that the radiation guide has at least one input-end or output-end deflecting surface with which the radiation that entered the radiation guide is guided at a right angle into the interior of the radiation guide or the radiation which is to be oriented out of the radiation guide onto the receiver is guided at a right angle out of the interior of the radiation guide. On the basis of these measures, transmitters and/or receivers can be arranged on the board without complex holders, thus also ensuring a precise positioning in a simple manner. The radiation guide can be produced as simply as was possible so far by means of corresponding shaping. Apart from the simpler production, the design also saves space and results in a miniaturization of the entire arrangement; it is possible in conjunction with other measures to use only one circuit board.
If it is provided that the at least one transmitter and the at least one receiver are configured as SMD (surface mounted device) components, the transmitter and the receiver can be mounted on the circuit board during the same operational step with which the remaining electrical components are mounted, thus further simplifying the production. This also accomplishes a very precise positioning of the transmitter and of the receiver.
The measure which provides that the beam entry surface and/or the beam exit surface are configured as convergent lenses permits the positioning of the transmitt
REFERENCES:
patent: 4676638 (1987-06-01), Yasuda
patent: 5661303 (1997-08-01), Teder
Pientka Rainer
Throl Manfred
Allen Stephone B.
Kunitz Norman
Robert & Bosch GmbH
Spencer George
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