Source: http://www.google.ca/patents/US6025872
Timestamp: 2013-05-26 00:00:25
Document Index: 275697690

Matched Legal Cases: ['art 122', 'art 122', 'art 126', 'art 122', 'art 122', 'art 122', 'art 122', 'art 122', 'art 122', 'art 122', 'art 124', 'art 122', 'art 124', 'art 124', 'art 122', 'art 122', 'art 122', 'art 124', 'art 124', 'art 124']

Patent US6025872 - Monitor region extension member and motor vehicle peripheral monitoring ... - Google PatentsSearch Images Maps Play YouTube News Gmail Drive More »Advanced Patent Search | Web History | Sign inAdvanced Patent SearchPatentsA motor vehicle peripheral monitoring apparatus uses a monitor region extension member as optical image forming means. The monitor region extension member comprises an upper image passage part and an upper image compression part. The upper image passage part includes a prism structural element of substantially...http://www.google.ca/patents/US6025872?utm_source=gb-gplus-sharePatent US6025872 - Monitor region extension member and motor vehicle peripheral monitoring apparatus using samePublication numberUS6025872 APublication typeGrantApplication number08/924,959Publication date15 Feb 2000Filing date8 Sep 1997Priority date9 Sep 1996InventorsTakeyuki AmariKazutomo FujinamiNaoto IshikawaToshiaki OzakiOriginal AssigneeYazaki CorporationU.S. Classification348/43359/837340/937348/61348/49348/148348/143348/E07.87International ClassificationB60R1/00H04N7/18H04N13/02Cooperative ClassificationH04N7/183European ClassificationH04N 7/18DReferencesPatent Citations (6)Referenced by (8)External LinksUSPTOUSPTO AssignmentEspacenetMonitor region extension member and motor vehicle peripheral monitoring apparatus using sameUS 6025872 AAbstract A motor vehicle peripheral monitoring apparatus uses a monitor region extension member as optical image forming means. The monitor region extension member comprises an upper image passage part and an upper image compression part. The upper image passage part includes a prism structural element of substantially a semi-conical shape whose prism apical angles become the maximum angle at the center of the member and are decreased toward the extremity from the center of the member. The upper image compression part includes a cylindrical structural element having a curved surface whose angles are set to be smaller continuously from the prism apical angles of the upper image passage part.
What is claimed is: 1. A monitor region extension member which is an optical member for acquiring, when image input means are used to acquire optical images of a monitor region surrounding a motor vehicle, optical images of an extended monitor region which is a predetermined region surrounding the monitor region, in addition to the optical images of the monitor region, said monitor region extension member comprising: an upper image passage part in the form of a prism disposed at the upper portion of said member, for optically refracting images of a first predetermined region containing at least said extended monitor region to acquire optical images of said first predetermined region; and an upper image compression member in the form of a cylindrical prism disposed continuously with said upper image passage part, for optically refracting images of a second predetermined region continuous with said first predetermined region to acquire optical images of said second predetermined region.
2. A monitor region extension member according to claim 1, wherein said upper image passage part includes a prism structural element of substantially a semi-conical shape whose prism apical angle becomes the maximum angle at the center of said member and is decreased toward the extremity of said member from the center of said member.
6. A motor vehicle peripheral monitoring apparatus using as optical image forming means said monitor region extension member according to claim 1, said motor vehicle peripheral monitoring apparatus comprising: image input means mounted in a motor vehicle, for picking up by way of said monitor region extension member serving as optical image forming means, when acquiring optical images of said monitor region, optical images of said extended monitor region in addition to optical images of said monitor region input from said monitor region extension member, to generate motor vehicle peripheral monitor information; and data processing means for monitoring the occurrence of an obstacle in the periphery of a motor vehicle on the basis of said motor vehicle peripheral monitor information.
7. A motor vehicle peripheral monitoring apparatus according to claim 6, wherein said monitor region is a region extending far from the rear vicinity of said motor vehicle, with said extended monitor region being a rear far region outside said monitor region, and wherein said upper image passage part is arranged such that images of at least said rear far region are input into said image input means, and wherein upper image compression part is arranged such that it optically compresses images of regions continuous with said rear far region but excluding said rear near region to input them into said image input means.
10. A motor vehicle peripheral monitoring apparatus according to claim 9, further comprising: a back gear detection sensor for detecting that a speed change gearing mechanism is at a back gear position to generate a detection signal; and a signal acquisition unit for outputting, upon a detection of the back gear position, the detection signal to said data processing means to urge the peripheral monitor control.
11. A motor vehicle peripheral monitoring apparatus according to claim 9, further comprising: a display alarm unit for generating a buzzer sound or a voice guidance on the basis of a drive signal output from said data processing means and for displaying a relative position between an obstacle and the motor vehicle or a message to the driver.
The upper image passage part 122 has a prism structural element 122.sub.strct of substantially a semi-conical shape in which a prism apical angle θ.sub.w (i.e., an angle (degrees) at the apex of the prism, which is represented as an angle formed between a curved surface 122.sub.srfc of the upper image passage part 122 and the planar part 126) results in its maximum angle (i.e., θ (degrees) at the center (a position ζ.sub.w =0 (degrees)) of the monitor region extension member 12 as shown in FIGS. 1C and 2 and in which the prism apical angle θ.sub.w is reduced toward the extremity (a position ζ.sub.w =ζ (degrees)) of the monitor region extension member 12 starting from its center as shown in FIGS. 1D and 2 (in other words, with the increased ζ.sub.w from the center shown in FIG. 1A).
More specifically, when a CCD camera 11 has a view angle θ.sub.1 of 90 degrees, the upward monitoring angle of the upper image passage part 122 is enlarged from 45 degrees to 65 degrees due to a prism insertion effect. Setting the prism apical angle θ.sub.1 at 20 degrees will widen the monitor region by 20 degrees.
The contour of the curved surface 122.sub.srfc of the prism structural element 122.sub.strct can be determined by a radius of curvature R shown in FIGS. 1B and 2.
FIG. 3 is a graphical representation for explaining a functional relationship between a sector angle ζ.sub.w and the prism apical angle θ.sub.w of the monitor region extension member 12 shown in FIGS. 1A to 1D.
The prism apical angle θ.sub.w is a predetermined function in which the sector angle ζ.sub.w of the prism structural element 122.sub.strct is a variable as shown in FIG. 3, and it is desirable that the prism apical angle θ.sub.w be set so that it is decreased accordingly as the sector angle ζ.sub.w increases.
In this manner, by providing the prism structural element 122.sub.strct having a prism apical angle θ.sub.w capable of being expressed by a predetermined function in which the sector angle ζ.sub.w is a variable, it becomes possible to secure an angle of incidence of a monitor image relative to a field angle θ.sub.MIN at the central position and to decrease the angle of incidence of the monitor image relative to the field angle θ.sub.MAX in the diagonal direction.
More specifically, the curved surface 122.sub.srfc of the prism structural element 122.sub.strct is preferably so contoured that the prism apical angle θ.sub.w is set to be large at the central position (i.e., the section S--S) as shown in FIG. 2 and that the prism apical angle θ.sub.w is set to be zero degree at the extremity (i.e., the section T--T) of the member, ζ.sub.w =ζ/2 with the gradually decreased prism apical angle θ.sub.w toward the extremity of the member in response to the sector angle ζ.sub.w from the central position as shown in FIG. 2.
FIG. 4 illustrates an optical path of an image of the monitor region 200 incident on the center (i.e., θ.sub.w =θ) of the monitor region extension member 12 of FIG. 1.
As regards region images which have optically passed through the upper image passage part 122, as shown in FIG. 4, the entire region images are shifted due to refracting function of the upper image passage part 122 (n.sub.0 ≦n.sub.1, where n.sub.0 =refractive index of air, n.sub.1 =refractive index of the upper image passage part 122) to enter the CCD camera 11. More specifically, an image incident on the upper image passage part 122 at an angle λ.sub.0 is shifted to a predetermined direction at an exit angle λ.sub.1 due to the refracting function of the upper image passage part 122.
By providing such an upper image passage part 122 having the prism structural element 122.sub.strct, it becomes possible to secure an angle of incidence of a monitor image relative to a field angle θ.sub.MIN at the central position and to decrease an angle of incidence of the monitor image relative to a field angle θ.sub.MAX in the diagonal direction.
This will ensure an extension of the monitor region 200 as well as a provision of satisfactory monitor images free from any eyesore, shaded portion 3 (see FIG. 12B) which has hitherto occurred arising from total reflection (that is, angle of incidence β.sub.A ≦critical angle Ic). As a result of this, an improved viewing environment can be given to the driver.
It is to be noted herein that the critical angle=arcsin (refractive index n.sub.0 of air/refractive index n1 of monitor region extension member 12), with n.sub.0 ≦n.sub.1, and the angle of incidence a α.sub.A =θ.sub.MAX.
Furthermore, by providing the prism structural element 122.sub.strct of substantially a semi-conical shape, there is achieved a compensation of the optical distortion in the horizontal direction, and satisfactory monitor images can be provided which are highly distinguishable with substantially no difference in a sense of distance between a picture of the monitor region 200 derived in the form of an output of the CCD camera 11 and the actual monitor region 200. As a result, an improved viewing environment can be given to the driver.
The upper image compression part 124 includes a cylindrical structural element 124.sub.strct having a curved surface which has been set to be of a small angle continuous with the prism apical angle θ.sub.w of the upper image passage part 122.
The contour of the curved surface of the cylindrical structural element 124.sub.strct can be determined by a radius of curvature R shown in FIGS. 1C, 1D, and 2.
By providing such a cylindrical structural element 124.sub.strct having a curved surface there is ensured an extension of the monitor region 200 as well as a provision of satisfactory monitor images free from any shaded portion arising from total reflection, with the result that an improved viewing environment can be given to the driver.
It is to be appreciated that the curved surface provided on the upper image compression part 124 is preferably comprised of the cylindrical structural element 124.sub.strct having a cylindrical surface whose prism apical angle is continuously decreased starting from the prism apical angle of the image passage part. By providing such an upper image compression part 124 including the cylindrical structural element 124.sub.strct with a cylindrical surface, it becomes possible to facilitate a further increase of the angle of incidence of the monitor images relative to the field angle θ.sub.MIN at the central position as well as a further decrease of the angle of incidence of the monitor images relative to the field angle θ.sub.MAX in the diagonal direction. Thus, there is ensured an extension of the monitor region 200 as well as a provision of satisfactory monitor images free from any shaded portion arising from total reflection, with the result that an improved viewing environment can be given to the driver. Furthermore, by optically continuously coupling the prism structural element 122.sub.strct with the cylindrical structural element 124.sub.strct there is ensured a provision of continuous monitor images freefrom any blind spot, with the result that an improved viewing environment can be given to the driver.
FIG. 6 is an analytical diagram of a ray for explaining an increment of the prism apical angle θ.sub.w required to extend the monitor region 200.
In order to upward extend by 10 degrees a monitor region 200 at the central portion of an image, as shown in FIG. 6, 11 degrees of prism apical angle θ.sub.w is required at the central portion of the monitor region 200.
FIG. 7 is a perspective view for explaining an prism apical angle θ.sub.w which is required for the monitor region extension member 12 of FIG. 1 to compensate the increment of the prism apical angle θ.sub.w in FIG. 6. FIG. 8 is a perspective view for explaining an optical positional relationship between the monitor region extension member 12 and the CCD camera 11 of FIG. 1.
In this embodiment, to compensate the increment (that is, 11 degrees) of the prism apical angle θ.sub.w at the central portion (ζ.sub.w =0 degree) in FIG. 6, the monitor region extension member 12 having the contour shown in FIG. 7 is disposed at the front part of a lens unit 112 of the CCD camera 11 in such a manner that their optical axes are coincident with each other (see FIG. 8).
By providing such an upper image passage part 122, it become possible to secure the angle of incidence of the images of the rear far region 200(C) relative to the field angle θ.sub.MIN at the central portion and to decrease the angle of incidence of the images of the rear far region 200(C) relative to the field angle θ.sub.MAX in the diagonal direction. Furthermore, there can be obtained monitor images which are highly distinguishable with substantially no difference in a sense of distance between the actual monitor region 200 and a picture of the monitor region 200 derived in the form of output of the CCD camera 11 through the compensation of the horizontal optical distortion. As a result of this, the driver can be given an improved viewing environment.
The prism structural element 122.sub.strct of the upper image passage part 122 associated with the image input means 10 (specifically, the CCD camera 11, see FIG. 8) has a convexedly or conically curved surface 122.sub.srfc whose prism apical angle θ.sub.w is decreased toward the extremity of the member in a predetermined rate as described in connection to FIG. 3.
By providing such an upper image passage part 122 having the prism structural element 122.sub.strct with convexedly or conically curved surface 11.sub.srfc, there is ensured an acquisition of images with less optical distortion over a wider monitor region 200.
Furthermore, it becomes possible for the thus acquired images with less optical distortion to secure the angle of incidence of the field angle θ.sub.MIN at the central position and to decrease the angle of incidence of the field angle θ.sub.MAX in the diagonal direction.
By arranging the upper image compression part 124 in this manner, it becomes possible to secure the angle of incidence of images of a wider area extending from the rear far region 200(C) up to the rear near region 200(A), relative to the field angle θ.sub.MIN at the central position and to decrease the angle of incidence of images of a wider area extending from the rear far region 200(C) up to the rear near region 200(A), relative to the field angle θ.sub.MAX in the diagonal direction. As a result, there is ensured an extension of the monitor region 200 with no optical distortion as well as a provision of satisfactory monitor images free from any shaded portion arising from total reflection, so that the driver can be given an improved viewing environment.
The cylindrical structural element 124.sub.strct of the upper image compression part 124 associated with the image input means 10 (the CCD camera 11) is so configured as to have a concavely curved surface 124.sub.srfc on the side of the image input means 10 as described hereinabove (see FIG. 8).
By disposing at the front part of the CCD camera 11 such an upper image compression part 124 having the cylindrical structural element 124.sub.strct with the concavely curved surface 124.sub.srfc, there is ensured an acquisition of images with less optical distortion over a wider monitor region 200.
Moreover, it becomes possible for the thus acquired images with less optical distortion to secure the angle of incidence of the field angle θ.sub.MIN at the central position and to decrease the angle of incidence of the field angle θ.sub.MAX in the diagonal direction.
BRIEF DESCRIPTION OF THE DRAWINGS The above and other aspects, objects, features and advantages of the present invention will become more apparent from the following detailed description in conjunction with the accompanying drawings, in which:
FIG. 3 is a graphical representation for explaining a functional relationship between a sector angle ζ.sub.w and the prism apical angle θ.sub.w of the monitor region extension member shown in FIGS. 1A to 1D;
FIG. 4 illustrates an optical path of an image of the monitor region 200 incident on the center (i.e., θ.sub.w =θ) of the monitor region extension member of FIGS. 1A to 1D.
FIG. 6 is an analytical diagram of a ray for explaining an increment of the prism apical angle θ.sub.w required to extend the monitor region;
FIG. 7 is a perspective view for explaining an prism apical angle θ.sub.w which is required for the monitor region extension member of FIGS. 1A to 1D to compensate the increment of the prism apical angle θ.sub.w in FIG. 6;
FIG. 13A is a perspective view for explaining the optical positional relationship between the monitor region extension member of FIGS. 12A and 12B and the CCD camera, and FIG. 13B is a sectional view taken along a line Q.sub.A -P.sub.A in FIG. 13A.
In such a monitor region extension member 2 and the motor vehicle peripheral monitoring apparatus using the same, as shown in FIG. 13A, it was possible to increase the field angle θ.sub.MAX in the diagonal direction (that is, the direction of axis Q.sub.A -P.sub.A) relative to the field angle θ.sub.MIN in the vertical direction (that is, the direction of Y-axis) at the central portion.
That is, it was possible to extend the monitor region since there could be increased the angle of incidence β.sub.A of ray output from the prism portion 2A toward the lens 4 as shown in FIG. 13B.
However, a monitor region extension member 2 and the motor vehicle peripheral monitoring apparatus using the same entailed a technical deficiency in that it was possible for the field angle θ.sub.MIN to extend the monitor region without causing any total reflection, but that for the field angle θ.sub.MAX the input angle β.sub.A tends to exceed the critical angle I.sub.c (=arcsin (n.sub.0 /n.sub.1), see FIG. 13B), resulting in frequent occurrence of the total reflection.
It would also be conceivable to decrease the prism apical angle of the monitor region extension member 2 in order to eliminate the total reflection (that is, β.sub.A ≦I.sub.c) caused by the increase of the field angle θ.sub.MAX. However, this would result in a simultaneous decrease of θ.sub.MIN at the central portion of the monitor region extension member 2, which would lead to a narrower monitor region at the central portion requiring widest monitor region. This is also a technical problem to be overcome.
SUMMARY OF THE INVENTION The present invention was conceived to overcome these drawbacks involved in the prior art. It is a particular object to extend the monitor region and to provide satisfactory monitor images free from any shaded portion arising from total reflection and further to further provide satisfactory monitor images which are fully distinguishable with substantially no difference in a sense of distance between the actual monitor region and a picture of the monitor region derived in the form of output of the CCD camera through the compensation of optical distortion, thereby providing an improved viewing environment to the driver, by means of a monitor region extension member and of a motor vehicle peripheral monitoring apparatus using the monitor region extension member an optical image forming means, the monitor region extension member comprising an upper image passage part and an upper image compression part, the upper image passage part including a prism structural element of substantially a semi-conical shape whose prism apical angle becomes the maximum angle at the center of the member and is decreased toward the extremity of the member from the center of the member, the upper image compression part including a cylindrical structural element having a curved surface whose angle is so set as to become smaller continuously from the prism apical angle of the upper image passage part
In accordance with the second aspect of the present invention, by providing such an upper image passage part having such a prism structural element it become possible in addition to the effect of the first aspect to secure the angle of incidence of the monitor images relative to the field angle θ.sub.MIN at the central portion and to decrease the angle of incidence of the monitor images relative to the field angle θ.sub.MAX in the diagonal direction.
In accordance with the fourth aspect of the present invention, by providing the upper image compression part having such a cylindrical structural element with a curved surface, it becomes possible in addition to the effect of any one of the first to third aspects to further increase the angle of incident of the monitor images relative to the field angle θ.sub.MIN at the central position and to facilitate a further decrease of the angle of incidence of the monitor images relative to the field angle θ.sub.MAX in the diagonal direction.
In accordance with the fifth aspect of the present invention, by providing the upper image compression part having such a prism structural element with a cylindrical surface, it becomes possible in addition to the effect of the fourth aspects to further increase the angle of incident of the monitor images relative to the field angle θ.sub.MIN at the central position and to facilitate a further decrease of the angle of incidence of the monitor images relative to the field angle θ.sub.MAX in the diagonal direction.
In accordance with the seventh aspect of the present invention, by providing such an upper image passage part, it become possible in addition to the effect of the sixth aspect to secure the angle of incidence of the images of the rear far region relative to the field angle θ.sub.MIN at the central portion and to decrease the angle of incidence of the images of the rear far region relative to the field angle θ.sub.MAX in the diagonal direction.
Similarly, by arranging the upper image compression part, it becomes possible to secure the angle of incidence of images of a wider area extending from the rear far region up to the rear near region, relative to the field angle θ.sub.MIN at the central position and to decrease the angle of incidence of images of a wider area extending from the rear far region up to the rear near region, relative to the field angle θ.sub.MAX in the diagonal direction.
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