Raindrop sensor having plano-convex lens

• US 6,507,015 B1
• Filed: 08/25/2000
• Issued: 01/14/2003
• Est. Priority Date: 08/27/1999
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Maeno, Satoru, Terakura, Osamu
• Primary Examiner(s): Allen, Stephone B.
• Assistant Examiner(s): Spears, Eric J
• Application Number:
  US09/645,620
• Time in Patent Office: 872 Days
• Field of Search: 250/216, 250/227.25, 250/574, 318/483, 340/602, 315/76-84
• US Class Current: 250/227.25
• CPC Class Codes: B60S 1/0822 characterized by the arrangement or type of detection means
• CPC Class Codes: B60S 1/0837 with a particular arrangement of the optical elements
• CPC Class Codes: B60S 1/0888 characterized by the attachment of the elements in a unit
• CPC Class Codes: G01N 21/43 by measuring critical angle

Abstract

A raindrop sensor has a prism body, incoming radiation side plano-convex lens portions each provided on inclined surfaces of the prism body for receiving light from light-emitting elements, and outgoing radiation side plano-convex lens portions provided on inclined surfaces of the prism body for emitting light toward a light-receiving element. The plano-convex lens portions are configured to cause a relatively small number of light-receiving element(s) to receive light from a number of outgoing radiation side plano-convex lens portions. Such a raindrop sensor can be made to have a more structure while employing a widened detection region.

Claims

1. A raindrop sensor comprising:

a prism body adapted for attachment to a member having a reference surface, the prism body having first and second incoming radiation side inclined surfaces inclined with respect to the reference surface, and first and second outgoing radiation side inclined surfaces inclined with respect to the reference surface in an opposite direction of the first and second incoming radiation side inclined surfaces, the first and second incoming radiation side inclined surfaces being parallel with each other, the first and second outgoing radiation side inclined surfaces being parallel with each other;

a wiring board provided to face the first and second incoming radiation side inclined surfaces and the first and second outgoing radiation side inclined surfaces of the prism body;

first and second incoming radiation side plano-convex lens portions respectively provided on the first and second incoming radiation side inclined surfaces with respective convex surfaces projecting outwardly;

first and second outgoing radiation side plano-convex lens portions respectively provided on the first and second outgoing radiation side inclined surfaces with respective convex surfaces projecting outwardly;

first and second light-emitting elements provided on the wiring board to face the first and second incoming radiation side plano-convex lens portions, respectively; and

a light-receiving element provided on the wiring board to face the first and second outgoing radiation side plano-convex lens portions, wherein;

the first outgoing radiation side plano-convex lens portion and the second outgoing radiation side piano-convex lens portion being complementary parts of a single plano-convex lens divided by a plane, wherein each of the first and second outgoing radiation side plano-convex lens portions has a divided surface defined by the plane;

the divided surface of each of the first and second outgoing radiation side piano-convex lens portions extending parallel to an optical axis of each of the first and second outgoing radiation side plano-convex lens portions;

the divided surface of the first outgoing radiation side plano-convex lens portion facing a first direction, which is perpendicular to the optical axis of each of the first and second outgoing radiation side plano-convex lens portions, and the divided surface of the second outgoing radiation side plano-convex lens portion facing a second direction, which is opposite to the first direction;

light, which internally exits the prism body via each of the first and second outgoing radiation side plano-convex lens portions entering the same light-receiving element; and

the second outgoing radiation side plano-convex lens portion being provided at an outgoing radiation side of the first outgoing radiation side plano-convex lens portion with respect to the first and second incoming radiation side plano-convex lens portions so that the divided surface of the second outgoing radiation side plano-convex lens portion faces the divided surface of the first outgoing radiation side plano-convex lens portion.

2. A raindrop sensor as in claim 1, wherein each of the first and second light-emitting elements and the light-receiving element is a surface-mounted element.

3. A raindrop sensor as in claim 1 wherein the first outgoing radiation side plano-convex lens portion is substantially the same size as that of the second outgoing radiation side plano-convex lens portion.

4. A raindrop sensor as in claim 1 wherein a convex surface of each of the first and second outgoing radiation side plano-convex lens portions has a curvature smaller than that of each of the first and second incoming radiation side plano-convex lens portions.

5. A raindrop sensor as in claim 1 wherein:

the divided surface of the first outgoing radiation side plano-convex lens portion extends in a direction perpendicular to the first outgoing radiation side inclined surface of the prism body; and

the divided surface of the second outgoing radiation side plano-convex lens portion extends in a direction perpendicular to the second outgoing radiation side inclined surface of the prism body.

6. A raindrop sensor for detecting raindrops on a detection surface, said sensor comprising:

a prism body having a first surface for facing the detection surface to detect raindrops on the detection surface, and a second surface provided at an opposite side of the first surface;

a member facing the second surface of the prism body;

a plurality of light-emitting elements each provided on the member to emit light toward the prism body;

a plurality of first side plano-convex lenses each provided on the second surface of the prism body to receive light from a corresponding one of the plurality of light-emitting elements;

a plurality of second side plano-convex lenses each provided on the second surface of the prism body to receive light passing through a corresponding one of the plurality of first side plano-convex lenses and reflected by the detection surface wherein the second side plano-convex lenses are complementary parts of a single plano-convex lens divided by at least one plane, and each of the second side plano-convex lenses having at least one divided surface, wherein each divided surface is defined by a corresponding one of the at least one plane; and

a light-receiving element provided on the member for receiving light from the plurality of second side plano-convex lenses, wherein;

each divided surface of each of the second side plano-convex lenses extends parallel to an optical axis of each of the second side plano-convex lenses;

one of the at least one divided surface of a first one of the second side plano-convex lenses faces a first direction, which is perpendicular to the optical axis of each of the second side plano-convex lenses, and one of the at least one divided surface of a second one of the second side plano-convex lenses, which is located next to one of the at least one divided surface of the first one of the second side plano-convex lenses, faces a second direction, which is opposite to the first direction; and

light, which exits each of the second side plano-convex lenses, entering the light-receiving element.

7. A raindrop sensor as in claim 6, wherein:

the second surface of the prism body has a plurality of first side inclined surfaces for holding the plurality of first side plano-convex lenses thereon, and a plurality of second side inclined surfaces for holding the plurality of second side plano-convex lenses thereon, the plurality of first side inclined surfaces being parallel with one another and making a specific angle with the reference surface, the plurality of second side inclined surfaces being parallel with one another and making an angle of substantially 90 degrees with respect the plurality of first side inclined surfaces.

8. A raindrop sensor as in claim 6, wherein

each of the plurality of second side plano-convex lenses receives light reflected by the detection surface and refracts the light toward a side of the divided surface thereof so that the refracted light enters the light-receiving element.

9. A raindrop sensor as in claim 6, wherein the light-receiving element is a single element.

10. A raindrop sensor as in claim 6, wherein:

the plurality of second side plano-convex lenses have an assumed optical axis of the one optical lens that can be cooperatively formed by the plurality of second side plano-convex lenses; and

the plurality of second side plano-convex lenses are shifted with respect to one another on the prism body in a direction parallel to the assumed optical axis.