Vehicle-mounted image recognition apparatus and method of manufacturing the same
First Claim
1. A vehicle-mounted image recognition apparatus comprising:
- a fixed-focus image-forming optical system having an optical axis, the image-forming optical system forming an image of a front scene at a rear position on the optical axis;
an image sensor disposed at the rear position on the optical axis of the image-forming optical system, the optical axis extending through an imaging plane of the image sensor; and
an integrated circuit obtaining data of the image captured by the image sensor and performing an image recognition process;
whereinat least a lower half of the imaging plane is located closer to a circumferential focus than a middle between a radial focus and the circumferential focus, at a position distant from an optical axis center of the image by about 70% of an image height of the image;
a distance between the circumferential focus and the imaging plane is smaller than a distance between the circumferential focus and the radial focus;
the integrated circuit recognizing a line indicating a traffic lane on a road surface in performing the image recognition process;
the radial focus is defined as a point at which a maximum radial resolving power of light converging through the image-forming optical system is obtained when a projection surface moves along the optical axis;
the circumferential focus is defined as a point at which a maximum circumferential resolving power of the converging light is obtained when the projection surface moves along the optical axis;
the lower half is defined as a portion of the imaging plane on which a lower half of the scene in a vertical direction is projected;
the image height is defined as half a diagonal length of the imaging plane; and
the optical axis center is defined as an intersection of the optical axis and the imaging plane.
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Abstract
In a vehicle-mounted image recognition apparatus, a resolution of an image projected on an imaging plane of an image sensor is different at a position away from a center between a circumferential direction and a radial direction. To make a circumferential resolution higher than a radial resolution, at least a lower half of the imaging plane is located closer to a circumferential focus than a middle of a radial focus and the circumferential focus at a position off the optical axis center of the image projected on the image sensor through the image-forming optical system. This is achieved by adjusting the position of the imaging plane when manufacturing or by selecting a lens with high circumferential resolution. This apparatus improves recognition accuracy in recognizing traffic lanes without using an expensive lens exhibiting high resolution both in the circumferential direction and in the radial direction.
12 Citations
39 Claims
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1. A vehicle-mounted image recognition apparatus comprising:
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a fixed-focus image-forming optical system having an optical axis, the image-forming optical system forming an image of a front scene at a rear position on the optical axis; an image sensor disposed at the rear position on the optical axis of the image-forming optical system, the optical axis extending through an imaging plane of the image sensor; and an integrated circuit obtaining data of the image captured by the image sensor and performing an image recognition process;
whereinat least a lower half of the imaging plane is located closer to a circumferential focus than a middle between a radial focus and the circumferential focus, at a position distant from an optical axis center of the image by about 70% of an image height of the image; a distance between the circumferential focus and the imaging plane is smaller than a distance between the circumferential focus and the radial focus; the integrated circuit recognizing a line indicating a traffic lane on a road surface in performing the image recognition process; the radial focus is defined as a point at which a maximum radial resolving power of light converging through the image-forming optical system is obtained when a projection surface moves along the optical axis; the circumferential focus is defined as a point at which a maximum circumferential resolving power of the converging light is obtained when the projection surface moves along the optical axis; the lower half is defined as a portion of the imaging plane on which a lower half of the scene in a vertical direction is projected; the image height is defined as half a diagonal length of the imaging plane; and the optical axis center is defined as an intersection of the optical axis and the imaging plane. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A method of manufacturing a vehicle-mounted image recognition apparatus, comprising:
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a focus measurement step of measuring the circumferential focus and the radial focus at a focus measurement position having an optical axis extending through an imaging plane;
an image-forming optical step of forming an image of a front scene at a rear position on the optical axis;
an obtaining data step of obtaining data of an image captured;
performing an image recognition step where at least a lower half of the imaging plane is located closer to a circumferential focus than a middle between a radial focus and the circumferential focus, at a position distant from an optical axis center of the image by about 70% of an image height of the image;
a distance between the circumferential focus and the imaging plane is smaller than a distance between the circumferential focus and the radial focus;
the image recognition step recognizing a line indicating a traffic lane on a road surface;
the radial focus being defined as a point at which a maximum radial resolving power of light converging through an image-forming optical system is obtained when a projection surface moves along the optical axis;
the circumferential focus is defined as a point at which a maximum circumferential resolving power of the converging light is obtained when the projection surface moves along the optical axis;
the lower half is defined as a portion of the imaging plane on which a lower half of the scene in a vertical direction is projected;
the image height is defined as half a diagonal length of the imaging plane; and
the optical axis center is defined as an intersection of the optical axis and the imaging plane;an imaging plane position adjustment step of moving an image sensor relative to the image-forming optical system so as to locate the imaging plane at a position which is closer to the circumferential focus than the middle between the radial focus and the circumferential focus and at which the distance between the circumferential focus and the imaging plane is smaller than the distance between the circumferential focus and the radial focus; and
a fixing step of relatively fixing the image sensor and the image-forming optical system;
wherein the focus measurement position is distant from the optical axis center by about half or more of a distance between the optical axis center and an edge of the imaging plane. - View Dependent Claims (23, 24, 25, 26, 27, 28)
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29. A vehicle-mounted image recognition apparatus comprising:
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a fixed-focus image-forming optical system having an optical axis, the image-forming optical system forming an image of a front scene at a rear position on the optical axis; an image sensor disposed at the rear position on the optical axis of the image-forming optical system, the optical axis extending through an imaging plane of the image sensor; and an integrated circuit obtaining data of the image captured by the image sensor and performing an image recognition process;
whereinat least in the lower half of the imaging plane located at a position of 70% of the image height from the optical axis center, a circumferential resolving power of an image projected on the image sensor by the imaging optical system is higher than a radial resolving power; the integrated circuit recognizing a line indicating a traffic lane on a road surface in performing the image recognition process; the radial focus is defined as a point at which a maximum radial resolving power of light converging through the image-forming optical system is obtained when a projection surface moves along the optical axis; the circumferential focus is defined as a point at which a maximum circumferential resolving power of the converging light is obtained when the projection surface moves along the optical axis; the lower half is defined as a portion of the imaging plane on which a lower half of the scene in a vertical direction is projected; the image height is defined as half a diagonal length of the imaging plane; and the optical axis center is defined as an intersection of the optical axis and the imaging plane. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
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Specification