Object sensing device and wiper controlling apparatus using the same

• US 20020190231A1
• Filed: 04/11/2002
• Published: 12/19/2002
• Est. Priority Date: 05/16/2001
• Status: Abandoned Application

• Current Assignee: Nippon Sheet Glass Company Limited (Nippon Telegraph and Telephone Corporation)
• Original Assignee: Nippon Sheet Glass Company Limited (Nippon Telegraph and Telephone Corporation)
• Inventors: Tsunetomo, Keiji, Tokuda, Tatsumi, Kobayashi, Fumitoshi, Yoshida, Harunobu
• Application Number:
  US10/122,975
• Publication Number:
  US 20020190231A1
• Time in Patent Office: Days
• US Class Current: 250/573
• 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 1/0844 including a camera
• CPC Class Codes: G01N 21/43 by measuring critical angle
• CPC Class Codes: G06T 2207/30168 Image quality inspection
• CPC Class Codes: G06T 2207/30252 Vehicle exterior; Vicinity of vehicle
• CPC Class Codes: G06T 7/0002 Inspection of images, e.g. flaw detection

Abstract

An object sensing device and an object sensing method in which a threshold does not have to be adjusted or updated even under the influence of external light are provided. The object sensing device includes a light source for irradiating a sensing surface, which is an external surface of a transparent substrate, an imaging optical system lens for forming an image by a light from the sensing surface, and a photo-detector array for receiving the image formed by the imaging optical system lens, the photo-detector array including a plurality of photo-detectors. The photo-detector array receives the light from the imaging optical system lens, and outputs a signal pattern that is an arrangement of light detection signals from the respective photo-detectors according to an arrangement of the photo-detectors and corresponds to a condition of an object present on the sensing surface. The object sensing device further includes a difference part for obtaining a differential signal of signal outputs from adjacent photo-detectors among the plurality of the photo-detectors according to the arrangement in the photo-detector array, and an object judging part for judging a presence of the object by detecting a presence of a pair of a positive peak and a negative peak in a pattern of the differential signal obtained by the difference part.

Claims

1. An object sensing device comprising:

a light source for irradiating a sensing surface, which is an external surface of a transparent substrate;

an imaging optical system lens for forming an image by a light from the sensing surface; and

a photo-detector array for receiving the image formed by the imaging optical system lens, the photo-detector array including a plurality of photo-detectors;

wherein the photo-detector array receives the light from the imaging optical system lens, and outputs a signal pattern that is an arrangement of light detection signals from the respective photo-detectors according to an arrangement of the photo-detectors and corresponds to a condition of an object present on the sensing surface,

the object sensing device further comprises

a difference part for obtaining a differential signal of signal outputs from adjacent photo-detectors according to the arrangement in the photo-detector array, and

an object judging part for judging a presence of the object by detecting a presence of a pair of a positive peak and a negative peak in a pattern of the differential signal obtained by the difference part.

2. The object sensing device according to claim 1, wherein the object judging part is provided with a threshold for each of the positive peak and the negative peak.

3. The object sensing device according to claim 1, further comprising an estimating part for estimating a covering ratio of the object present on the sensing surface from a ratio between a total length of the photo-detector array and a sum of lengths, each being a length between a pair of the photo-detectors on the photo-detector array corresponding to a pair of the positive peak and the negative peak on the differential signal pattern.

4. The object sensing device according to claim 1, further comprising an estimating part for estimating a size of the object present on the sensing surface by converting a length between a pair of the photo-detectors on the photo-detector array corresponding to a pair of the positive peak and the negative peak on the differential signal pattern into a length on the sensing surface.

5. The object sensing device according to claim 1, further comprising an estimating part for estimating a covering ratio of the object present on the sensing surface from a ratio of a sum of signal lengths of the differential signal pattern, each being a signal length between positions of the pair of the positive peak and the negative peak along a differential signal arrangement, with respect to a total length of the differential signal pattern.

6. The object sensing device according to claim 1, wherein the object is a raindrop or a muddy water droplet.

7. A wiper controlling apparatus for controlling a wiper using a detection information from the object sensing device according to claim 1.

8. A wiper controlling apparatus for controlling a wiper using a detection information from the object sensing device according to claim 2.

9. A wiper controlling apparatus for controlling a wiper using a detection information from the object sensing device according to claim 3.

10. A wiper controlling apparatus for controlling a wiper using a detection information from the object sensing device according to claim 4.

11. A wiper controlling apparatus for controlling a wiper using a detection information from the object sensing device according to claim 5.

12. A wiper controlling apparatus for controlling a wiper using a detection information from the object sensing device according to claim 6.

14. The object sensing method according to claim 13, wherein the presence of the object is judged based on a threshold for each of the positive peak and the negative peak.

15. The object sensing method according to claim 13, wherein a covering ratio of the object present on the sensing surface is estimated from a ratio between a total length of the photo-detector array and a sum of lengths, each being a length between a pair of the photo-detectors on the photo-detector array corresponding to a pair of the positive peak and the negative peak on the differential signal pattern.

16. The object sensing method according to claim 13, wherein a size of the object present on the sensing surface is estimated by converting a length between a pair of the photo-detectors on the photo-detector array corresponding to a pair of the positive peak and the negative peak on the differential signal pattern into a length on the sensing surface.

17. The object sensing method according to claim 13, wherein a covering ratio of the object present on the sensing surface is estimated from a ratio of a sum of signal lengths of the differential signal pattern, each being a signal length between positions of the pair of the positive peak and the negative peak along a differential signal arrangement, with respect to a total length of the differential signal pattern.

18. The object sensing method according to claim 13, wherein the object is a raindrop or a muddy water droplet.

13. An object sensing method for sensing an object present on a sensing surface, which is an external surface of a transparent substrate, with a light source for irradiating the sensing surface, an imaging optical system lens for forming an image by a light from the sensing surface, and a photo-detector array for receiving the image formed by the imaging optical system lens, the photo-detector array including a plurality of photo-detectors, the object sensing method comprising:

with the photo-detector array, receiving the light from the imaging optical system lens, and outputting a signal pattern that is an arrangement of light detection signals from the respective photo-detectors according to an arrangement of the photo-detectors and corresponds to a condition of the object present on the sensing surface;

obtaining a differential signal of signal outputs from adjacent photo-detectors according to the arrangement in the photo-detector array; and

judging a presence of the object by detecting a presence of a pair of a positive peak and a negative peak in a pattern of the obtained differential signal.