DETECTION APPARATUS AND METHOD

• US 20130027557A1
• Filed: 07/16/2012
• Published: 01/31/2013
• Est. Priority Date: 07/29/2011
• Status: Active Grant

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Hirai, Hideaki, Itoh, Izumi
• Granted Patent: US 9,187,063 B2
• Time in Patent Office: Days
• US Class Current: 348/148
• CPC Class Codes: B60S 1/0844 including a camera
• CPC Class Codes: G01N 21/21 Polarisation-affecting properties G01N21/19 takes precedence
• CPC Class Codes: G06V 20/56 exterior to a vehicle by using sensors mounted on the vehicle

Abstract

A substance detection apparatus and method including a light source to emit light to a planar transparent member having a proximal first face and a distal second face opposite the first face, the light from the light source first striking the first face of the planar transparent member. The substance detection apparatus and method including an image capture lens, a polarization filter, an image sensor, and a substance detection processor. The light emitted from the light source is reflected at the substance present on the second face of the planar transparent member, and the image sensor receives light reflected from the substance, via the image capture lens and the polarization filter, to capture an image of the substance present on the second face of the planar transparent member.

Claims

1. A substance detection apparatus, comprising:

a light source to emit light to a planar transparent member, having a proximal first face and a distal second face opposite the first face, the light from the light source first striking the first face of the planar transparent member;

an image capture lens;

a polarization filter;

an image sensor; and

a substance detection processor that executes a detection process to detect a substance present on the second face of the planar transparent member based on an image of the substance captured by the image sensor,

wherein the polarization filter, disposed after the image capture lens and before the image sensor with respect to a direction of the light entering the image sensor, passes only a polarized light component having a polarized light direction substantially parallel to a virtual plane including an optical axis of the light source that emits the light to the planar transparent member and an optical axis of the image capture lens,

wherein the image sensor is composed of a two-dimensional array of pixels having a plurality of light receiving elements,

wherein the light emitted from the light source is reflected at the substance present on the second face of the planar transparent member, the image sensor receives a light reflected from the substance, via the image capture lens and the polarization filter, to capture an image of the substance present on the second face of the planar transparent member.

2. The substance detection apparatus of claim 1, wherein the focus of the image capture lens is set at a point in the distance beyond the planar transparent member.

3. The substance detection apparatus of claim 1, wherein the light source includes a plurality of light sub-sources,

wherein the polarization filter includes a plurality of polarization filter areas arranged in a two-dimensional array and having different transmission axes,

each one of the polarization filter areas corresponding to a unit area on the image sensor, the unit area on the image sensor being composed of one light receiving element or two or more light receiving elements,

wherein each one of the polarization filter areas is set with a transmission axis to pass only a polarized light component having a polarized light direction parallel to a virtual plane including an optical axis of the light source that inputs the greatest incidence light amount to a relevant polarization filter area, and an optical axis of the image capture lens.

4. The substance detection apparatus of claim 1, wherein the polarization filter employs a wire grid structure.

5. The substance detection apparatus of claim 1, further comprising a light separation filter,

wherein the light source emits the light having a specific wavelength band and the light separation filter selects only the light including the specific wavelength band emitted from the light source,

wherein the image sensor captures an image of the substance via the polarization filter and the light separation filter.

6. The substance detection apparatus of claim 1, wherein the image sensor is segmented into a first pixel array and a second pixel array,

wherein the first pixel array of the image sensor captures an image of a substance present on the planar transparent member,

wherein the second pixel array of the image sensor captures an object in the distance beyond the planar transparent member,

the substance detection apparatus further including an object detection processor to conduct a detection process of the object in the distance based on an image captured by the second pixel array of the image sensor,

wherein the substance detection processor conducts the substance detection process based on an image captured by the first pixel array of the image sensor.

7. The substance detection apparatus of claim 1, wherein the image capture lens, the polarization filter, and the image sensor are combined to form an image capture device.

8. A method of detecting a substance, comprising the steps of:

emitting light, using a light source, to a planar transparent member, having a proximal first face and distal second face opposite the first face, the light from the light source first striking the first face of the planar transparent member;

when the light emitted from the light source is reflected at a substance on the second face of the planar transparent member, receiving light reflected from the planar transparent member by an image capture lens;

passing, via a polarization filter, only a polarized light component having a polarized light direction substantially parallel to a virtual plane including an optical axis of the light source that emits the light to the planar transparent member and an optical axis of the image capture lens;

capturing an image of the substance present on the second face of the planar transparent member by using an image sensor composed of a pixel array having a plurality of light receiving elements arrayed two dimensionally, based on the light reflected from the planar transparent member and passed through the polarization filter; and

detecting the substance based on the image of substance captured by the image sensor.

9. A non-transitory computer-readable storage medium storing a program that, when executed by a computer, causes the computer to execute a method of detecting a substance, comprising the steps of:

emitting light, using a light source, to a planar transparent member, having a proximal first face and distal second face opposite the first face, the light from the light source first striking the first face of the planar transparent member;

when the light emitted from the light source is reflected at a substance on the second face of the planar transparent member, receiving light reflected from the planar transparent member by an image capture lens;

passing, via a polarization filter, only a polarized light component having a polarized light direction substantially parallel to a virtual plane including an optical axis of the light source that emits the light to the planar transparent member and an optical axis of the image capture lens;

capturing an image of the substance present on the second face of the planar transparent member by using an image sensor composed of a pixel array having a plurality of light receiving elements arrayed two dimensionally, based on the light reflected from the planar transparent member and passed through the polarization filter; and

detecting the substance based on the image of substance captured by the image sensor.