U.S. patent application number 09/750938 was filed with the patent office on 2001-05-24 for method for forming constant radius convex mirror assembly.
This patent application is currently assigned to Rosco, Inc.. Invention is credited to Englander, Benjamin.
Application Number | 20010001342 09/750938 |
Document ID | / |
Family ID | 23780870 |
Filed Date | 2001-05-24 |
United States Patent
Application |
20010001342 |
Kind Code |
A1 |
Englander, Benjamin |
May 24, 2001 |
Method for forming constant radius convex mirror assembly
Abstract
A safety mirror lens assembly includes a mirror unit with a
mirror lens that has a three-dimensional convex/ellipsoid
reflective surface which terminates in an oval or round or other
shape peripheral edge. The reflective surface is such that a
notional line traced to coincides with the major axis has a first
constant radius of curvature and a second notional line traced to
coincide with the minor axis has a second constant radius of
curvature. The first radius of curvature is substantially greater
than the second radius of curvature. The mirror lens is usable for
a cross-over mirror for a vehicle, for example, a school bus.
Inventors: |
Englander, Benjamin;
(Jamaica, NY) |
Correspondence
Address: |
OSTROLENK FABER GERB & SOFFEN
1180 AVENUE OF THE AMERICAS
NEW YORK
NY
100368403
|
Assignee: |
Rosco, Inc.
|
Family ID: |
23780870 |
Appl. No.: |
09/750938 |
Filed: |
December 29, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09750938 |
Dec 29, 2000 |
|
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09448579 |
Nov 23, 1999 |
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Current U.S.
Class: |
29/450 ;
29/428 |
Current CPC
Class: |
B60R 1/082 20130101;
G02B 5/10 20130101; Y10T 29/4987 20150115; Y10T 29/49826
20150115 |
Class at
Publication: |
29/450 ;
29/428 |
International
Class: |
B23P 011/02 |
Claims
What is claimed is:
1. A method of fabricating a mirror unit, comprising the steps of:
producing by injection molding, a mirror lens having a reflective
outer surface and a rear surface, the mirror lens comprising a
mirror lens body which terminates in an oval shape peripheral edge
that surrounds the reflective surface, the mirror lens body being a
substantially three-dimensional, convex body having a major axis of
a first length and a minor axis which intersects the major axis and
has a second length, the major axis and the minor axis being
defined in a plane that contains the oval shape peripheral edge,
the outer mirror surface having a first constant radius of
curvature along a first line thereof which coincides with the major
axis and having a second, constant radius of curvature on the outer
surface thereof along a second line which coincides with the minor
axis of the lens, said first constant radius of curvature being
substantially larger than said second constant radius of curvature;
and providing a mirror back and coupling the mirror back to the
mirror lens body; and providing a coupling structure and attaching
the coupling structure to the mirror back.
2. The method of claim 1, including attaching the mirror back to
the lens by means of a gasket made of resilient synthetic
material.
3. The method of claim 1, in which the mirror lens body comprises a
plurality of notional trace lines each of which has said second,
constant radius of curvature, wherein each of said plurality of
trace lines lies in a plane which also contains said vertical
axis.
4. The method of claim 3, in which the mirror lens body includes a
second plurality of notional trace lines, each one of said second
plurality of notional trace lines having a respective, constant
radius of curvature.
5. A method of fabricating a mirror unit comprising the step of:
producing by injection molding, a mirror lens having a reflective
outer surface and a rear surface, the mirror lens comprising a
mirror lens body which terminates in a circular peripheral edge
that surrounds the reflective surface, the mirror lens body being a
substantially three-dimensional, spherical body, the outer mirror
surface having a constant radius of curvature along any trace line
thereof which begins at a first point on the peripheral edge,
terminates on a second point on the peripheral edge and lies in a
plane that also contains a vertical axis around which the spherical
mirror lens body is symmetrically arranged, each trace line having
the same constant radius of curvature; and attaching to the mirror
lens a mirror assembly structure including a mirror back adjacent
the continuous peripheral edge of the mirror lens; a fastening
structure for fastening the mirror back to the mirror lens; and a
coupling structure attached to the mirror back, the coupling
structure including hardware for engaging a mirror pole which
serves to attach the mirror unit to a vehicle body in a manner
which allows the orientation of the mirror lens to be adjusted.
6. A method of fabricating a mirror unit comprising the steps of:
producing by injection molding, a mirror lens having a reflective
outer surface and a rear surface, the mirror lens comprising a
mirror lens body which terminates in a peripheral edge that
surrounds the reflective surface, the mirror lens body having a
substantially three-dimensional, spherical body, the outer mirror
surface having a constant radius of curvature along any straight,
unidirectional trace line thereof, which trace line begins at a
first point on the peripheral edge and terminates on a opposed
second points on the peripheral edge; and attaching to the mirror
lens a mirror assembly structure including a mirror back adjacent
the peripheral edge of the mirror lens; a fastening structure for
fastening the mirror back to the mirror lens; and a coupling
structure attached to the mirror back, the coupling structure
including hardware for engaging a mirror pole which serves to
attach the mirror unit to a vehicle body in a manner which allows
the orientation of the mirror lens to be adjusted.
Description
RELATED APPLICATION
[0001] This is a continuation application under the provisions of
37 C.F.R. 1.53(b) of pending application Ser. No. 09/448,579, filed
Nov. 23, 1999, by BENJAMIN ENGLANDER, entitled OVAL, CONSTANT
RADIUS CONVEX MIRROR ASSEMBLY, the contents of which application is
hereby incorporated by reference.
BACKGROUND OF THE INVENTION
[0002] This invention generally relates to convex, three
dimensional mirrors and, more particularly, to a mirror assembly,
sometimes referred to as a "cross-over" mirror, which affords a bus
driver, for example, a school bus driver, visual access in front of
the school bus which is hidden from direct view as well as
alongside the bus. Such cross-over mirrors can however also be used
at the rear corners of a vehicle such as with trucks, mail vans and
the like.
[0003] For many decades, cross-over mirrors and mirror assemblies
have been deployed on school buses and are in fact required by
federal and local regulations. A substantial body of prior art has
been published describing various mirrors of the type to which the
present invention relates. An exemplary list of such prior art
includes U.S. Pat. Nos.: 4,822,157; 4,730,914; 4,436,372;
5,084,785; 5,589,984 and Des. 346,357. The above list represents
but a fraction of the extensive prior art on the subject of
cross-over mirrors and their accessories such as mounting hardware,
mirror poles and other implements by which such mirror assemblies
are secured to vehicles such as busses, school buses, trucks and
the like. The contents of the aforementioned United States patents
are incorporated by reference herein.
[0004] The convex, three-dimensional surface of the mirror lens
described, for example, in the aforementioned 4,436,372 patent,
terminates in a continuous, peripheral edge which is essentially
circular. That (and other similar) mirrors have a generally
elliptical, i.e. dome, shape.
[0005] In more recent years, the prior art has moved to provide
convex, three dimensional mirror lens surfaces that have a more
stretched, elongate general shape. The aforementioned U.S. Pat.
Nos.: 4,822,157; 4,730,914; 4,436,372; 5,084,785; 5,589,984 and the
Des. 346,357 illustrate the general style of such mirrors.
[0006] For the purposes of the present invention it is important to
note that, essentially as a rule, the three dimensional, generally
elliptical or convex surfaces of the aforementioned elongate
cross-over mirror lens were provided with radii of curvature
(measured along planar cross-sections) which were measurably
non-constant, i.e. tending to increase or decrease from the center
point on the mirror lens toward its peripheral, circumferential
edge.
[0007] As an example, the convex, ellipsoid mirror lens shown in
U.S. Pat. No. 4,436,372 has a generally flatter, i.e. less curved,
center surface, which surface curves sharper as one proceeds toward
the peripheral edge. Stated differently, the "radius of curvature"
of the surface decreases from the center where the major and minor
axis of the mirror surface intersect toward the peripheral edge of
the mirror. A similar relationship is specifically claimed for the
elongate, oval mirror that is described in the aforementioned
5,589,984 patent. In another patent, an opposite relationship is
specified--the sharpest curvature is at the center, as the mirror
surface flattens out as one proceeds toward the peripheral edge. In
the mirror lens of the 4,730,914 patent, the inventors stress the
fact that the mirror surface has a generally constant radius of
curvature at a central portion of the mirror representing about one
half of the entire surface and different radii of curvature at the
other portions of the mirror lens.
[0008] In part, the present inventor perceives that the prior art
was constrained by the type of technology commonly used in the
industry for forming a mirror lens, which technology inherently
imparts non-uniform radii of curvature to the mirror lens. Indeed,
at least some people adhered to a conventional wisdom that it is
desirable to vary the radius of curvature so as to obtain a larger
and less distorted image at the mirror center, but a greater field
of view, through the provision of a more distorted image, at the
peripheral regions on the mirror. The idea is to increase the space
that the mirror monitors in and around the school bus or the
like.
SUMMARY OF THE INVENTION
[0009] It is an object of the present invention to provide an
elongate, generally oval, convex/ellipsoid mirror lens that
improves the ability to discern the movements of children around
and about school buses and other types of vehicles.
[0010] The foregoing and other objects of the present invention are
realized by an oval mirror lens and associated mounting parts which
allow the mirror lens to be mounted to a vehicle to provide a field
of view in front of and alongside of the vehicle. The mirror lens
is oval, substantially convex and has, due to its oval shape, a
major axis and a minor axis. These axes intersect one another at
right angles at the center point (or apex) of the lens.
[0011] The mirror lens has an oval-shaped peripheral edge and the
key aspect of the invention resides in the fact that a line traced
along the major axis of the lens from one point on the periphery to
the juxtaposed, opposite point on the periphery has a first
constant radius of curvature. Similarly, a line traced on the
surface of the lens along the minor axis from one end point on the
periphery to the juxtaposed point on the periphery has a second
radius of curvature. The first radius of curvature is larger than
the second radius of curvature. The resulting mirror surface
produces images of objects which more faithfully maintain the width
and height proportions of the object, e.g. a child's image, that is
reflected from different portions of the mirror lens.
[0012] The present invention also relates to a method for
fabricating the mirror lens of the present invention to attain a
lens having the constant radii of curvature feature referenced
above.
[0013] Thus, the present invention revolves around the notion that
one obtains a mirror in which the height/width proportions of
objects placed around the school bus are subject to less variation,
as compared to mirrors of the prior art. By means of the novel
mirror of the present invention, a bus driver is less likely to
lose sight of a child moving about the school bus, which is of
course very important to the safety of our children.
[0014] Other features and advantages of the present invention will
become apparent from the following description of the invention
which refers to the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIGS. 1a, 1b, 1c, and 1d are, respectively, a perspective, a
rear view, a first side view, and a second side view, of the mirror
of the present invention.
[0016] FIG. 2 is a line drawing which shows the curved lines that
are defined by the mirror lens of the present invention along the
major and minor axes thereof.
[0017] FIG. 3 shows the oval, peripheral outline of the present
invention with the major or minor axes superimposed thereon.
[0018] FIG. 4 shows a torus of which a slice has been taken to
fabricate the mirror lens of the present invention.
[0019] FIGS. 5a and 5b show the mirror of the present invention
with bracketry and mounting hardware for mounting the same to a
vehicle body.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
[0020] With reference to the drawings, the present invention
relates to a cross-over mirror assembly 10 (FIGS. 5a and 5b) which
broadly comprises a mirror unit 20 which is supported by a mirror
pole 30 which is in turn attached to a vehicle body by a mirror
pole mount 40. Mirror pole braces, such as the braces 32, 34 and
36, serve to stiffen the structure and to assist in the attachment
of the mirror unit 20 to a vehicle body in a manner which dampens
vibrations.
[0021] The present invention focuses on the mirror lens 21 and,
more specifically, on the precise shape of its three-dimensional
body. First, it is noted (with reference to FIG. 5b) that the
mirror lens 21 has afixed to the rear thereof a mirror back 22
which is attached to the mirror lens body 21 by a gasket 28, which
may be made of rubber or of any resilient synthetic material. The
mirror back 22 supports a coupling plate 24 which in turn supports
a mirror pole attachment that is known in the art. For example, it
can be a tunnel mount style or a swivel ball style mirror pole
attachment.
[0022] With reference to FIG. 1, the mirror lens body 21 has a
front surface 23 which is coated with a reflective substance to
form a reflective surface. The rear (not shown) of the mirror lens
body 21 is non-reflective, but it may be reflective. The peripheral
edge 29 (FIG. 2) of the mirror lens body 21 is oval shaped and
coincides with the contour of the gasket 28.
[0023] FIGS. 1b, 1c, and 1d together show the mirror unit 20
including the backplate 24 and the coupling structure 26 which as
illustrated can be a swivel bolt joint to which a mirror pole can
be attached by suitable bracketry (not shown).
[0024] The point of novelty of the present invention lies in the
careful formation of the shape of the outer surface 23 of the
mirror lens body 21. The lens body 21 is defined by an oval shaped
peripheral edge 29 and its convex/ellipsoid body which is so
contoured as to attain certain radius of curvature relationships as
described below.
[0025] With reference to FIG. 2, it is an essential feature of the
present invention that a line 62 that is traced along the outer
reflective surface 23 of the mirror lens, which line coincides with
the major axis 58 of the mirror lens body, has a first constant
radius of curvature. Similarly, a notional line 60 traced along the
mirror surface, which line 60 coincides with the minor axis 56 of
the mirror lens outer reflective surface, has a second, different
but constant radius of curvature. The two notional lines 60 and 62
intersect at the center, i.e., apex, of the reflective surface
23.
[0026] The aforementioned radius of curvature relationships have
been selected for the cross-over mirror lens of the present
invention in order to reduce variations in the height and width
proportional dimensions of images of objects on the mirror surface,
as the objects move around or about the bus, or in other words, as
the object image moves away from the center region of the mirror
lens towards its peripheral regions (closer to the peripheral edge
29).
[0027] In the embodiment of the present invention, the first radius
of curvature "R" is nearly 50% larger than the radius curvature "r"
which coincides with a minor axis of the oval perimeter 29 of the
mirror lens. Preferably, the size of the first major axis is in the
range of from about 10 to 14 inches and the second minor axis
ranges between 7.5 to 11.5 inches.
[0028] It is not a trivial task to produce a mirror lens of having
the parameters outlined above. With reference to FIG. 4, it is
noted that one mode of obtaining the mirror shape of FIG. 2 is by
taking a slice of the torus structure 50 shown in FIG. 4. Such
hollow torus 50 (only a portion of which is illustrated)
circumscribed or surrounds an axis 55. Therefore, in accordance
with basic geometrical principles, the outermost peripheral line of
the torus 50 has a constant radius of curvature about the axis 55.
Yet again, any cross section 57, 59 (FIG. 4) of the torus taken in
a plane that contains the axis 55 describes a circle of constant
radius that is equal to "r."
[0029] Therefore, if a portion of the torus is cut away to produce
a toroidal segment, that toroidal segment constitutes the
three-dimensional mirror lens shown in FIG. 2. The line 54 in FIG.
4 is the segment cutting line and that line 54 coincides with
peripheral edge 29 of the mirror lens of FIG. 2. The toroidal
segment 52 is cut away from the toroid 50, for example by a cutting
plane that extends parallel to the axis line 55 and perpendicular
to a line extending from the center of the segment 52 to the axis
55 to which it is also perpendicular. Any trace on the lens surface
that lies in a plane that also contains the axis 55 has a constant
radius of curvature "r." On the other hand, any trace on the lens
surface that lies in a plane that is parallel to the plane
containing the longitudinal trace 62 has a constant radius of
curvature. The actual radius of curvature of such traces that are
successively traced below and then above the trace line 62 in FIG.
2 is larger, the closer the trace is to the trace line 62.
[0030] The toroidal segment constituting the lens body 21 of the
present invention is preferably fabricated by injection molding
which, while being a well known molding technique, has not been
typically used in the fabrication of mirror lens of the type
described herein. To this end, it is possible to prepare a mold
having a toroidal segment shape described above and to inject that
mold with suitable material to form the lens body 21.
[0031] FIG. 3 diagrammatically illustrates the peripheral edge 29
of the mirror lens including its major axis 58 and minor axis
56.
[0032] This invention can also be applied to round, spherical,
three-dimensional mirror lenses wherein the axes (major and minor)
are equal. The radius of curvature will be equal and constant along
all notional lines traced along the outer surface which also
intersect the center point of the outer surface, i.e., which pass
through the axis of the spherical body.
[0033] Although the present invention has been described in
relation to particular embodiments thereof, many other variations
and modifications and other uses will become apparent to those
skilled in the art. It is preferred, therefore, that the present
invention be limited not by the specific disclosure herein, but
only by the appended claims.
* * * * *