Raindrop detection apparatus

• US 20060076477A1
• Filed: 09/22/2005
• Published: 04/13/2006
• Est. Priority Date: 09/28/2004
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Ishikawa, Junichi
• Granted Patent: US 7,468,523 B2
• Time in Patent Office: Days
• US Class Current: 250/227.250
• CPC Class Codes: B60S 1/0822 characterized by the arrangement or type of detection means
• CPC Class Codes: B60S 1/0833 Optical rain sensor
• CPC Class Codes: B60S 1/0888 characterized by the attachment of the elements in a unit

Abstract

A raindrop detection apparatus includes a light emitting unit for emitting light to an inner side of a windshield, a light receiving unit for receiving the light reflected by an outer surface of the windshield, a first lens unit which is arranged between the windshield and the light emitting unit to convert the light from the light emitting unit into parallel light, and a second lens unit which is arranged between the windshield and the light receiving unit to converge the reflected light at the light receiving unit. The second lens unit is larger than a radial cross section of the reflected light. An amount of raindrop landed on the outer surface of the windshield is detected based on an intensity of the light received by the light receiving unit.

Claims

1. A raindrop detection apparatus comprising:

at least one light emitting unit for emitting light toward an inner side of a windshield;

a light receiving unit for receiving the light reflected by an outer surface of the windshield;

at least one first lens unit which is arranged between the windshield and the light emitting unit to convert the light from the light emitting unit into parallel light; and

a second lens unit which is arranged between the windshield and the light receiving unit to converge the reflected light at the light receiving unit, wherein;

the second lens unit is larger than a radial cross section of the reflected light; and

an amount of raindrop landed on the outer surface of the windshield is detected based on an intensity of the light received by the light receiving unit.

2. The raindrop detection apparatus according to claim 1, further comprising

a light conducting unit arranged between an inner surface of the windshield, and the first and second lens units, the light conducting unit conducting the parallel light to the windshield and conducting the reflected light to the second lens unit.

3. The raindrop detection apparatus according to claim 1, wherein each of the first lens unit and the second lens unit is made of one of polycarbonate, polymethyl methacrylate, acrylic resin and polyester.

4. The raindrop detection apparatus according to claim 1, wherein:

the first lens unit is divided into two parts by a first virtual plane, which extends along a central axis of the first lens unit and intersects the windshield at a substantially same angle with that between the central axis and the windshield, the two parts being arranged to offset from each other so that distances from the light emitting unit to the two parts become different and a difference between perpendicular heights of the two parts with respect to the windshield becomes small; and

the second lens unit is divided into two parts by a second virtual plane, which extends along a central axis of the second lens unit and intersects the windshield at a substantially same angle with that between the central axis and the windshield, the two parts being arranged to offset from each other so that distances from the light receiving unit to the two parts become different and a difference between perpendicular heights of the two parts with respect to the windshield becomes small.

5. The raindrop detection apparatus according to claim 2, further comprising

a case unit, in which the first lens unit, the second lens unit and the light conducting unit are accommodated, wherein

the case unit, the first lens unit, the second lens unit and the light conducting unit are constructed integrally.

6. The raindrop detection apparatus according to claim 5, further comprising

a circuit board, at which the light emitting unit and the light receiving unit are mounted, the circuit board being supported by the case unit.

7. The raindrop detection apparatus according to claim 6, further comprising

a connector for electrically connecting the circuit board with an external, wherein

the first lens unit and the second lens unit are surrounded by the case unit, the circuit board, and the connector to be in a substantially closed state.

8. The raindrop detection apparatus according to claim 4, wherein:

the two parts of the first lens unit offset from each other along the first virtual plane, and divided surfaces of the two parts are arranged to contact each other; and

the two parts of the second lens unit offset from each other along the second virtual plane, and divided surfaces of the two parts are arranged to contact each other.

9. The raindrop detection apparatus according to claim 2, further comprising

a silicon sheet arranged between the light conducting unit and the inner surface of the windshield.