RAIN DETECTION APPARATUS AND METHOD

• US 20120169877A1
• Filed: 02/22/2012
• Published: 07/05/2012
• Est. Priority Date: 07/16/2002
• Status: Active Grant

• Current Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Original Assignee: TRW Limited (Zeppelin - Stiftung der Stadt Friedrichshafen)
• Inventors: Heenan, Adam John, Thompson, Martin John, Buchanan, Alastair James, Hazelden, Roger John
• Granted Patent: US 8,861,780 B2
• Time in Patent Office: Days
• US Class Current: 348/148
• CPC Class Codes: B60S 1/0822 characterized by the arrangement or type of detection means
• CPC Class Codes: B60S 1/0844 including a camera
• CPC Class Codes: B60S 1/485 including control systems responsive to external conditions, e.g. by detection of moisture, dirt or the like
• CPC Class Codes: B60S 1/603 the operation of at least a part of the cleaning means being controlled by electric means
• CPC Class Codes: G06T 7/254 involving subtraction of images
• CPC Class Codes: G06V 20/56 exterior to a vehicle by using sensors mounted on the vehicle

Abstract

A rain detection apparatus includes a camera that views a surface and a processor that captures an image from the camera. The processor generates a signal indicative of rain on the surface from information contained in the captured image and optionally drives a surface cleaning apparatus in response thereto. The apparatus captures images focused at a plurality of distances. The processor includes an edge detector that detects edges visible in the captured image and a difference structure that calculates the difference between the number of edges visible between differing images. The edge detector disregards edges close to areas of light larger than the largest raindrop that is desired or expected to be detected. The apparatus optionally includes a backlight, and the difference in numbers of edges between frames with and without the backlight illuminated are used to distinguish between background features and rain on the surface.

Claims

1. A rain detection apparatus comprising:

a camera adapted to view a surface being a window of a vehicle; and

a processor adapted to capture at least one image from the camera, wherein

the processor is further adapted to generate at least one signal indicative of the presence of rain on the surface from information contained in the at least one captured image, and

the apparatus is adapted to capture images focused at a plurality of distances comprising a first distance corresponding to viewing the window of the vehicle and a second distance corresponding to viewing a road ahead of the vehicle.

2. The rain detection apparatus of claim 1 wherein each image captured by the camera is focused at a plurality of distances.

3. The rain detection apparatus of claim 2 wherein the camera comprises a multi-focal lens.

4. The rain detection apparatus of claim 3 wherein the multi-focal lens is a bi-focal lens.

5. The rain detection apparatus of claim 1 wherein the processor is furthermore arranged to sense the location of other vehicles or of lane markings on the road.

6. A method of detecting the presence of rain on a surface being a window of a vehicle comprising the steps of:

capturing images of the surface; and

then determining the presence of rain on the surface from the captured images, wherein the captured images are focused at a plurality of distances comprising a first distance corresponding to viewing the window of the vehicle and a second distance corresponding to viewing a road ahead of the vehicle.

7. The method of claim 6 wherein each captured image is focused at a plurality of distances.

8. The method of claim 6 further including the step of detecting the positions of lanes or vehicles surrounding a vehicle from information contained in the at least one captured image.