WO2008112309A1

WO2008112309A1 - Multi-curvature convex mirror having enhanced field of vision

Info

Publication number: WO2008112309A1
Application number: PCT/US2008/003435
Authority: WO
Inventors: Junzhong Wu; Huang Sheng
Original assignee: Smith, Edward, N.; Samolis, Thomas, J.; Hangzhou Qili Mirror Industry Co., Ltd
Priority date: 2007-03-14
Filing date: 2008-03-14
Publication date: 2008-09-18
Also published as: EP2130069A4; CN201017053Y; US20090231740A1; EP2130069A1

Abstract

A multi-curvature convex mirror is comprised of a reflective surface having a first reflective sub-area having a first curvature and a second reflective sub-area having a second curvature. The first and second reflective sub-areas are collectively defined by a series of locations, each defined by an x, y and z coordinate, determined in accordance with the relationship z = x/a + y/b where 600 ≤ a ≤ 1,300 and 100 ≤ |b-a| ≤ 200. If the multi-curvature convex mirror is configured to provide a vertically oriented field of vision, the relationship is further limited by the requirement that a<b. Conversely, if the multi-curvature convex mirror is configured to provide a horizontally oriented field of vision, the relationship is further limited by the requirement that a>b.

Description

TITLE

Multi-Curvature Convex Mirror having Enhanced Field of Vision FIELD OF THE DISCLOSURE

The present disclosure relates to mirrors and, more particularly, to a convex mirror having multiple reflecting surfaces, each having a respective curvature.

BACKGROUND

To enhance safety during operation thereof, many vehicles, for example, trucks, buses and automobiles, employ mirror systems that enable the drivers of the vehicles to see behind and/or to the side of the vehicle without turning their head in that direction. Such mirror systems typically include an interiorly-located mirror, commonly known as a "rear view" mirror, mounted in proximity to the upper interior side surface of the windshield and a pair of exteriorly-located mirrors, commonly known as "side view" mirrors, respectively mounted on a forward portion of the door assemblies for the driver and front seat passenger.

Most mirrors used to enable a driver to look behind or to one side of a vehicle may be classified as flat, convex or aspherical mirrors. A flat mirror has a generally planar reflective surface that tends to produce true and undistorted reflections of objects. However, because the field of vision produced by the planar reflective surface is relatively narrow, e.g., is typically bounded by planes generally orthogonal to the edges of the reflective surface, flat mirrors are characterized by a relatively large blind spot. In contrast, a convex mirror has a curved reflective surface and, when compared to a flat mirror, is generally characterized by a greater field of vision and a smaller blind spot. Indeed, as the curvature of the reflective surface is increased, the field of vision for the convex mirror increases while the size of the blind spot decreases. Thus, a mirror having a convexly curved reflecting surface will rectify many of the shortcomings of a mirror having a generally flat reflecting surface. Unfortunately, convex mirrors are not without their own shortcomings, most notably, distortions in the images of objects reflected thereby and difficulties when attempting to accurately judge the distance separating the mirror from the reflected objects. Furthermore, the severity of these shortcomings tends to worsen as the curvature of the reflective surface increases.

An aspherical mirror typically includes two or more convexly curved mirror surfaces, each of which is curved to a different extent. For example, one aspherical mirror known in the art includes primary and secondary reflective surfaces. The primary reflective surface encompasses approximately two-thirds of the aspherical mirror and is a convex mirror having a relatively small curvature of the reflective surface which causes the primary reflective surface to approximate that of a flat mirror. Accordingly, reflections appearing in the primary reflective surface are true and undistorted. The secondary reflective surface, on the other hand, covers approximately one-third of the aspherical mirror and is a convex mirror having a larger curvature of the reflective surface relative to the curvature of the primary reflective surface. Accordingly, the secondary reflective surface compensates for a portion of the relatively narrow field of view and the blind spot characterizing flat mirrors (or close approximations thereto) such as the primary reflective surface. The transition from the primary reflective surface to the secondary reflective surface is smooth, thereby minimizing any problems resulting from the difference between the undistorted image/smaller field of vision of the primary reflective surface and the relatively more distorted/greater field of vision of the secondary reflective surface. However, as most aspherical mirrors require a relatively large difference in the degree to which the secondary reflective surface is curved in order to remove any blind spots caused by the primary reflective surface, the transition between the primary and secondary reflective surfaces remains relatively sharp and, as a result, continues to affect proper judgment of the distance separating the mirror and an object reflected thereby.

It should be readily appreciated that a multi-curvature convex mirror which combines the advantages of a larger field of view and a reduced or eliminated blind spot when compared to a flat mirror while simultaneously reducing the distortion and difficulty in estimating separation distances normally associated with convex mirrors would enjoy many advantages over both flat and convex mirrors currently in use. Such a multi-curvature convex mirror is described hereinbelow. SUMMARY

In an embodiment, claimed herein is a multi-curvature convex mirror comprised of a reflective surface having a first reflective sub-area having a first curvature and a second reflective sub-area having a second curvature. The first and second reflective sub-areas are collectively defined by a series of locations, each defined by an x, y and z coordinate, determined in accordance with a common relationship.

In one aspect thereof, the multi-curvature convex mirror is configured to provide a vertically oriented field of vision.

In another aspect thereof, the multi-curvature convex mirror is configured to provide a horizontally oriented field of vision. In still another aspect thereof, the multi-curvature convex mirror is employed as a side- view mirror for a vehicle.

In still yet another aspect thereof, the multi-curvature convex mirror is employed as a rear-view mirror for a vehicle.

In still other aspects thereof, the common relationship for determining the series of locations which collectively define the first and second reflective sub-areas of the reflective surface is z = | + ^ where 600 < a < 1,300, 100 < |b-a| < 200 and a<b for the case where the

X V multi-curvature convex mirror is configured for a vertically oriented field of view or z = - + - where 600 < a < 1,300, 100 < |b-a| < 200 and a>b for the case where the multi-curvature convex mirror is configured for a horizontally oriented field of view. DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present disclosure, and for further details and advantages thereof, reference is now made to the drawings accompanying this disclosure, in which:

FIG. 1 is a perspective view of a multi-curvature convex mirror configured in accordance with the teachings set forth herein;

FIG. 2 is a first side view of the multi-curvature convex mirror of FIG. 1; FIG. 3 is a second side view of the multi-curvature convex mirror of FIG. 1 ; FIG. 4 is a top view of the multi-curvature convex mirror of FIG. 1 ; FIG. 5 illustrates the field of view for a vertically oriented embodiment of the multi- curvature convex mirror of FIGs. 1-4; and

FIG. 6 illustrates the field of view for left horizontally oriented and right horizontally oriented embodiments of the multi-curvature convex mirror of FIGs. 1-4.

DETAILED DESCRIPTION

The teachings set forth herein are susceptible to various modifications and alternative forms, specific embodiments of which are, by way of example, shown in the drawings and described in detail herein. It should be clearly understood, however, that the drawings and detailed description set forth herein are not intended to limit the disclosed teachings to the particular form disclosed. On the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of that which is defined by the claims appended hereto.

Accordingly, collectively referring now to FIGs. 1-4, a mirror 100, for example, a side view mirror commonly employed by trucks, buses and automobiles, having a true and undistorted field of vision like that normally associated with a flat mirror but without the blind spot produced by such mirrors will now be described in greater detail. As may now be seen, the mirror 100 has a top side surface 102 which serves as a reflective surface for the mirror 100 and a bottom side surface 1 12 that serves as a base for the mirror 100. As may be further seen, the reflective surface 102 has a generally rectangular shape that is defined by a first edge surface 104, a second edge surface 106, the second edge surface 106 being longer than and generally orthogonal to the first edge surface 104, a third edge surface 108 generally orthogonal to the second edge surface 106, the third edge surface 108 being approximately the same length as and generally parallel to the first edge surface 104 and a fourth edge surface 110 generally orthogonal to the third edge surface 108, the fourth edge surface 110 being approximately the same length as and generally parallel to the second edge surface 106. As best seen in FIGs. 2 and 3, the general center of the mirror 100 bulges outwardly relative to the edge surfaces 104, 106, 108 and 1 10. Thus, the mirror 100 is a member of the family of mirrors commonly referred to as convex mirrors. It should be clearly understood, however, that the specific shape and relative dimensions of the convex mirror 100 illustrated in FIGs. 1 -4 is purely exemplary and that it is fully contemplated that the convex mirror 100 may be of a wide variety of shapes and sizes. The reflective surface 102 of the convex mirror 1 10 is a m u lti -curvature surface comprised of a first reflective sub-area having a first curvature and a second reflective sub-area having a second curvature. The reflective surface 102 is comprised of a series of locations, each of which is defined by a set of coordinates (x,y,z). The series of locations may be determined by application of the following equation: x y z = - + - a b where: x is the coordinate, along the x-axis, of a location on the reflective surface 102 of the multi-curvature convex mirror 100. y is the coordinate, along the y-axis, of a location on the reflective surface 102 of the multi-curvature convex mirror 100; z is the coordinate, along the z-axis, of a location on the reflective surface 102 of the multi-curvature convex mirror 100; a is a first constant; and b is a second constant.

Locations, on the reflective surface 102 of the multi-curvature convex mirror 100 are determined by setting x to a first series of integral values such as 0, 1, 2, 3,..., N (or, if desired, to a series of non-integral values), setting y to a second series of integral such as 0, 1, 2, 3,..., N (or, if desired, to a second series of non-integral values) and solving for z when a is set to have a range from 600 to 1 ,300 i.e., 600 < a < 1,300 and 100, and the absolute value of the difference between b and a shall be no less than 100 and no more than 200, i.e., 100 < |b-a| < 200. Importantly, depending on the process by which locations for the reflective surface 102 of the multi-curvature convex mirror 100 are determined, the reflective surface 102 of the multi- curvature convex mirror 100 may have a vertically oriented field of view such as the field of view 204 produced by the multi-curvature convex mirror 200 illustrated in FIG 5 or a horizontally oriented field of view such as the field of view 216, 218 produced by the multi- curvature convex mirror 220, 222, respectively, illustrated in FIG. 6. In this regard, however, it should be noted that, if the reflective surface 102 of the multi-curvature convex mirror 100 is to have a vertically oriented field of view, the additional condition that a is less than b should be applied to the above equation when determining the locations corresponding to the reflective surface 102 of the multi -curvature convex mirror 100. Conversely, if the reflective surface 102 of the multi-curvature convex mirror 100 is to have a horizontally oriented field of view, the additional condition that a is greater than b should be applied to the above equation.

From the determined coordinates of the reflective surface 102 of the multi-curvature convex mirror 100, a mold to be used in manufacturing the multi-curvature convex mirror 100 may be formed. When forming the mold, it is recommended that rectangular material of approximately twice the size of the dimensions of the desired multi-curvature convex mirror 100, for example, mold square stock, be employed. The center of the rectangular material is then designated as the point of origin (0,0,0) from which the locations corresponding to the reflective surface 102 of the multi-curvature mirror 100 are identified. For a vertically oriented field of view, the locations of the reflective surface 102 of the multi-curvature convex mirror 100 are determined by proceeding downwardly from the point of origin. For a horizontally oriented field of view, locations of the reflective surface 102 of the multi-curvature convex mirror 100 are determined by proceeding to the right of the square mold stock (if a right horizontally oriented multi-curvature convex mirror such as mirror 222 is desired) or by proceeding to the left of the square mold stock (if a left horizontally oriented multi-curvature convex mirror such as the mirror 220 is desired). From the mold, the multi-curvature convex mirror 100 having the desired reflective surface 102 may be manufactured utilizing conventional techniques. The resultant multi-curvature convex mirror 100 is characterized by an enhanced field of view relative to conventional mirrors currently employed as rear or side view mirrors. For example, FIG. 5 shows the vertically oriented field of view 202 when the side view mirror of vehicle 200 is a conventional mirror 200 and the enhanced vertically oriented field of view 204 when side view mirror of vehicle 200 is a multi-curvature convex mirror. Further by way of example, FIG. 6 shows the left and right horizontally oriented field of views 212 and 214 when side view mirrors 220 and 222, respectively, of vehicle 206 are conventional mirrors and the left and right horizontally oriented field of views 216 and 218 when side view mirrors 220 and 222, respectively, of vehicle 206 are multi-curvature convex mirrors. As further seen in FIG. 6, the enhanced field of view 216, 218 resulting from use of the multi-curvature convex mirrors as the side view mirrors 220, 222 enable a driver to see vehicle 208, 210, respectively, both of which are outside the field of view 212, 214.

While a number of embodiments of a multi-curvature convex mirror have been shown and described herein, modifications thereof may be made by one skilled in the art without departing from the spirit and the teachings of the invention. The embodiments described herein are exemplary only, and are not intended to be limiting. Many variations, combinations, and modifications of the embodiments disclosed herein are possible and are within the scope of the teachings set forth herein. Accordingly, the scope of protection is not limited by the description set out above but is only defined by the claims appended hereto

Claims

1. A multi-curvature convex mirror, comprising: a reflective surface having a first reflective sub-area having a first curvature and a second reflective sub-area having a second curvature, said first and second reflective sub-areas collectively defined by a series of locations, each defined by an x, y and z coordinate, determined in accordance with a common relationship.

2. The multi-curvature convex mirror of claim 1, wherein said multi-curvature convex mirror is configured to provide a vertically oriented field of vision.

3. The multi-curvature convex mirror of claim 1, wherein said multi-curvature convex mirror is configured to provide a horizontally oriented field of vision.

4. The multi-curvature convex mirror of claim 1, 2 or 3, wherein said multi-curvature convex mirror is employed as a side-view mirror for a vehicle.

5. The multi-curvature convex mirror of claim 1, 2 or 3, wherein said multi-curvature convex mirror is employed as a rear-view mirror for a vehicle.

6. The multi-curvature convex mirror of claim 1, 2, 3, 4 or 5, wherein said common relationship for determining said series of locations which collectively define said first and second reflective sub-areas of said reflective surface of said multi-curvature convex mirror further comprises: z = - ^x + , - y a b where: 600 < a < 1,300; and

100 < |b-a| < 200.

7. The multi-curvature convex mirror of claim 1 , 2, 4 or 5, wherein said common relationship for determining said series of locations which collectively define said first and second reflective sub-areas of said reflective surface of said multi-curvature convex mirror further comprises:

a b where:

600 < a < 1,300;

100 < |b-a| < 200; and a<b.

8. The multi-curvature convex mirror of claim 1 , 2, 3 or 5, wherein said common relationship for determining said series of locations which collectively define said first and second reflective sub-areas of said reflective surface of said multi-curvature convex mirror further comprises: x y z = -+ - a b where: 600 < a < 1,300;

100 < |b-a| < 200; and a>b.