Optical: systems and elements – Mirror – With mirror surface of varied radius
Patent
1997-01-06
2000-05-30
Shafer, Ricky D.
Optical: systems and elements
Mirror
With mirror surface of varied radius
359727, G02B 510, B60R 106
Patent
active
060697555
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to mirror, in particular, to a vehicular mirror.
BACKGROUND OF THE INVENTION
The prior art vehicular rear-view mirror is either flat or spherical in shape, which provides narrowly viewing and blind spots. Accordingly, it is not helpful for safe driving.
To improve the prior art mirror, Chinese Utility Model No. 90206894.6, filed on May 26, 1990, disclosed a rear-view mirror for a vehicle in which the reflecting surface of the mirror is a convex shape, which is composed of a number of spherical surfaces of different curvature that are smoothly joined with each other and the curvature of the convex gradually increases from the top to the bottom i.e., the curvature of the upper portion of the reflecting surface is small or even zero while the curvature of the lower portion of the reflecting surface is large. Moreover, the curvature of the reflecting surface gradually increases along its lower portion as it is away from the body of the vehicle. This mirror is better than others since its viewing is broader and clear while the blind spots are eliminated. However, since the curvature of such a mirror increases only along the vertical direction and remains unchanged on the upper portion of the mirror along the horizontal direction, its viewing is not wide enough on the upper portion of the mirror.
SUMMARY OF THE INVENTION
Therefore, a principal object of the present invention is to provide a rear-view mirror for vehicle that has a wide viewing without blind spots.
A further object of the present invention is to provide a clear mirror image with a distortion that is tolerable to human sight.
The reflecting surface of the mirror in accordance with the present invention is a convex shape composed of a plurality of differential curved surfaces that are smoothly joined with each other. An average of the curvature on the differential curved surfaces gradually increases along both the vertical direction from the top to bottom and the horizontal direction away from the body of the vehicle.
The change of the curvature in both vertical and horizontal directions of the mirror in accordance with the present invention may be either homogeneous or inhomogeneous. In the latter case, the variation rate of the average of the curvature also gradually increases along both the vertical direction from the top to the bottom of the mirror and the horizontal direction away from the body of the vehicle.
As the average of the curvature increases in both vertical and horizontal directions of the mirror in accordance with the present invention, the differences among the average curvature of each differential curved surface should be kept within such a range that the image in the mirror in accordance with the present invention is clear and the distortion of the image is within a tolerance that is acceptable to human sight.
As one aspect of the present invention, since the distance from a driver to a left mirror and a right mirror is different, the curvatures and the variation rates of the differential curved surfaces are corresponding different. For a vehicle that has a driver's seat on the left-side, the left mirror, of course, is closer than the right mirror to the driver. Therefore, the curvature on the lower and outer portion is smaller than that of the right mirror and the variation rate of the curvature is smaller than that of the right mirror either. It is clearly understood that this principle applies in obvious manner to a situation in which the driver seat is on the right side of the vehicle.
In accordance, with the present invention, the range of the average of the curvature and the variation rate along both vertical and horizontal directions of the mirror will depend on the viewing range and the contour of the mirror. The wider desired viewing range is requested, the larger will be the variation in the range of the average. For example, for the same viewing range, the smaller the contour of the mirror becomes, the larger will be the variation rate of the average, and the
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Nirmel Chittaranjan N.
Shafer Ricky D.
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