U.S. patent number 3,639,899 [Application Number 04/832,300] was granted by the patent office on 1972-02-01 for programmed traffic signal and method of using.
This patent grant is currently assigned to Minnesota Mining and Manufacturing Company. Invention is credited to Gunnar R. Ljungkull.
United States Patent |
3,639,899 |
Ljungkull |
February 1, 1972 |
PROGRAMMED TRAFFIC SIGNAL AND METHOD OF USING
Abstract
A signal or display device comprising a condensing lens,
aperture means having all aperture-defining edges located
substantially at the focus of the lens, and a light source for
providing diffuse illumination to the lens from the focus and from
the entire aperture, contains a moveable filter member for
interposing between source and lens and located substantially at
said focus.
Inventors: |
Ljungkull; Gunnar R. (White
Bear Lake, MN) |
Assignee: |
Minnesota Mining and Manufacturing
Company (St. Paul, MN)
|
Family
ID: |
25261272 |
Appl.
No.: |
04/832,300 |
Filed: |
June 11, 1969 |
Current U.S.
Class: |
362/284;
340/907 |
Current CPC
Class: |
F21V
17/02 (20130101); G08G 1/095 (20130101) |
Current International
Class: |
F21V
17/00 (20060101); F21V 17/02 (20060101); G08G
1/095 (20060101); F21q 003/02 (); F21v
013/14 () |
Field of
Search: |
;340/25,84,87,383,110 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Habecker; Thomas B.
Assistant Examiner: Cohen; Howard S.
Claims
I claim:
1. A display device comprising a condensing lens defining a viewing
surface and having a focus, aperture-defining means having all
aperture-defining edges substantially at said focus, and lighting
means, including a diffusion plate substantially at said focus, for
providing diffuse illumination to said lens from said focus and
from the entire aperture, and said device being further
characterized as including a filter plate, and means for mounting
said filter plate so as to permit placing any desired portion of
its said area adjacent said aperture and substantially at said
focus whereby to alter the display at the viewing surface.
2. Apparatus of claim 1 wherein said filter plate comprises at
least two differently colored light-transmitting segments.
3. Apparatus of claim 2 wherein said filter plate comprises
adjacent segments of complementary colors each of an area equal to
that of said aperture.
4. Apparatus of claim 1 including drive means for placing any
desired segment of said filter plate adjacent said aperture.
5. Apparatus of claim 4 wherein said drive means includes
programmed control means for establishing a repetitive sequence of
placings of said segments.
6. For use as a traffic control system, a display device according
to claim 1 wherein said filter plate has adjacent red and green
segments and including means for advancing said plate across said
aperture in the direction from green to red at a slow uniform rate
consistent with anticipated rate of traffic advance and for
abruptly returning said plate in the reverse direction.
7. Method of controlling stop-and-go traffic in a control zone from
a traffic signal adjacent said zone and having a view lens,
comprising displaying at said lens a "go" indication to traffic at
sufficiently short distances from said signal to permit safe
transit through said zone at normal zone speed, while
simultaneously displaying at said lens a "stop" indication to
traffic at greater distances.
8. Apparatus of claim 1 wherein said lighting means includes a
diffusion plate substantially at said focus.
9. Apparatus of claim 1 wherein said diffusion plate and said
filter plate are correspondingly concave.
10. Apparatus of claim 9 wherein said filter plate consists
essentially of adjacent red and green segments each of an area
equal to that of said aperture.
11. A display device comprising a condensing lens defining a
viewing surface and having a focus, aperture-defining means having
all aperture-defining edges substantially at said focus, and
lighting means for providing diffuse illumination to said lens from
said focus and from the entire aperture, and said device being
further characterized as including a colored filter stencil at said
lens, a filter plate comprising at least one colored segment, and
means for mounting said filter plate so as to permit placing any
desired portion of its said area adjacent said aperture and
substantially at said focus whereby to alter the display at the
viewing surface.
12. Apparatus of claim 11 wherein said filter plate has one segment
of the same color as said colored filter stencil and another
segment of a complementary color.
Description
This invention relates to highway beacon and other display devices.
An important embodiment is in the form of a traffic control light
having particular utility as a distance-dependent stop-and-go
signal, and the invention will for convenience be described
primarily in such context.
The invention makes possible the control of traffic at an
intersection in somewhat the following manner. During the period of
change from "go" to "stop" indication, normally involving the
change from a green to a red signal, the green signal will remain
visible to a motorist who is sufficiently close to the intersection
to permit him to cross safely before completion of the change. At
the same time, a motorist who is at too great a distance to safely
pass the intersection will receive a red or "stop" indication on
the signal, and will therefore be aware that he must stop on
reaching the intersection.
Appeldorn U.S. application Ser. No. 571,639, now U.S. Pat. No.
3,457,400, describes a highway beacon or other display device in
which the entire viewing surface appears uniformly illuminated to a
viewer located within a prescribed viewing area. The device
comprises a condensing lens defining the viewing surface, aperture
means with all aperture-defining edges located substantially at the
focus of said lens, and lighting means providing diffuse
illumination to the lens from the focus and from the entire
aperture. The shape and size of the aperture is conformed to
correspond with the desired viewing area. Movement of an observer
from within to outside of that area provides that observer with a
sharp cutoff of the illumination, whereas from all points within
the defined area the observer sees the signal as fully and
uniformly illuminated.
The present invention adds to the display device of the Appeldorn
disclosure the further capability of progressively altering the
appearance of the signal within the predetermined field of view.
The entire signal area may remain in view and illuminated but the
appearance, e.g., the color, of the signal may be changed; or the
viewing area may be restricted, or expanded, or otherwise altered
in any of a number of ways.
The invention will now be further described in connection with the
appended drawing, in which:
FIG. 1 is a front elevation of the display device,
FIG. 2 is an elevation in section approximately as indicated by
section 2--2 of FIG. 4,
FIG. 3 is a top plan view in section approximately as indicated by
section 3--3 of FIG. 4,
FIG. 4 is a view in perspective of the control device of FIGS.
1-3,
FIG. 5 is a view in elevation of the cam member of FIG. 3,
FIG. 6 is a schematic representation showing a typical installation
of a device of this invention in use as a traffic control
signal,
FIG. 7 is a view in elevation of one form of aperture means as used
in the device of FIG. 6,
FIGS. 8 and 9 are views in front elevation showing alternate forms
of image-changing screen elements and associated supporting
members, and
FIG. 10 is a schematic representation in perspective showing the
relationship between selected components of a modified form of the
device.
As shown in FIGS. 1-4, the highway beacon 10 consists of a housing
11 supported on a fixed standard 12 and having at the open forward
end a transparent protective panel and a condensing or view lens
13, here illustrated as a Fresnel lens. A transparent curved plate
14 centrally located at the rear of the housing 11 is situated
substantially at the focus of the lens 13 and is illuminated from a
source 15 supported within an extension 16, of the housing 11,
serving as a light box. Diffuse illumination of the lens area from
the focus is provided, for example by employing a diffuse
reflecting surface within the housing extension 16 or on a separate
reflector 38 inserted therewithin, as shown in FIG. 2, and by using
a frosted envelope for the source 15; or by providing a frosted or
light diffusing surface on the plate 14; or preferably by
introducing a separate diffusion plate 37. The requirements of
condensing lens, source of diffuse light, and aperture means are
further described and illustrated in application Ser. No.
571,639.
A light-transmitting filter plate 17 is supported on vanes 18, 19
which are pivotally mounted at the sides of the casing 11 on pivots
20, 21. The filter plate is in the form of a narrow elongate
segment of a sphere having a slightly shorter radius than that of
the plate 14, the width being approximately that of the plate 14
and the length approximately twice the width as indicated in FIGS.
2 and 3 and in FIG. 8. The convex surface of the filter plate 17
and the concave surface of the transparent plate 14 are nearly in
contact and both surfaces are substantially at the focus of the
lens 13 over the area of the plate 14.
Vane 18 carries an outwardly extended peg 22 passing through a
suitable slot in the housing 11 and serving as a cam follower. The
peg meshes with a face cam 23 rotatably supported on a
constant-speed motor drive unit 24 contained within an extension 35
of the housing 11.
In a typical installation, the filter plate 17 is divided into two
equal portions 25 and 26, typically red and green respectively as
indicated in FIG. 8. The cam 23 is designed to permit slow uniform
progress of the filter plate as it is moved across the plate 14 in
the direction from green to red, while causing rapid movement in
the reverse direction as the rotation of the cam is continued
through a complete cycle.
The action of the signal as just defined will be described with
reference to FIG. 6, showing two cars 27 and 28 approaching an
intersection 29 protected with a beacon 10 operated by a control
station 30. At the position shown in FIG. 6, the control station
has just initiated a change in the beacon from the "go" to the
"stop" condition. To the driver of car 27 within the area of the
lower beam 31, the beacon will continue to exhibit a "go" signal as
he approaches and passes the intersection at a normal rate of
speed. At the same time, the driver of car 28 who is within the
area of the upper beam 32, i.e., in back of the moving boundary
line 33, defining the position of the boundary between colored
areas 25 and 26 of the plate 17, will observe a change in the
signal from the "go" to the "stop" condition, and will therefore be
in a position to decelerate smoothly and to stop short of the
intersection 29. An additional signal, not shown, will then direct
his further actions.
A different application of the display device of this invention is
indicated in FIG. 10, showing a transparent colored stencil 34
directly adjacent the lens 13 and a filter plate 17, having a lower
segment 26 identical in color to the stencil 34 and an upper
segment 25 having a complementary color, in front of the plate 14.
Typically, and as indicated in the FIG, the stencil 34 and lower
segment 26 will be red, while the upper segment 25 will be green.
When the filter plate is in the lowermost position, the transmitted
green rays are stopped by the red filter areas of the stencil 34
but reach the lens through the arrow-shaped cutout portion 39, so
that to the approaching motorist the signal shows only a central
green arrow. As the filter plate is moved upwardly, placing the red
lower segment 26 adjacent the plate 14, the transmitted red rays
from the source reach the stencil and lens, and the entire surface
of the lens then appears substantially uniformly red to the
observer from a position within the defined viewing area forwardly
of the device.
The outlines of the viewing area may be readily fixed, as described
in Ser. No. 571,639, by appropriately locating the edges of the
orifice from which the diffuse light from the source passes to the
lens 13. One convenient way of establishing the desired orifice is
by applying opaque masking tape or other suitable masking means in
an appropriate pattern to the rear surface of the transparent or
diffuse light-transmitting plate 14, for which purpose the
extension casing 16 is made readily removable, e.g., by hinge 40
and screw clamp 41, so that the image focused on the plate by the
lens 13, in the manner of a camera obscura, may be readily seen.
Where diffusion of the light is obtained by means other than a
diffusion plate 14, such plate may be omitted, using in its place a
stencil or mask insert the inner edges of which are substantially
at the focus of the lens 13 and define the limits of the orifice.
In the latter modification the surface of the filter plate may
itself be light-diffusing. A typical orifice pattern is shown in
FIG. 7, wherein the transparent central portion corresponds to the
view of the highway focused on the plate 14' in a beacon 10 located
as shown in FIG. 6.
Various other applications of the principles of the invention may
be mentioned. Various patterns may be provided on the filter plate
or at the stencil 34, for example in obtaining unique and
attention-arresting effects in display advertising. Vehicular
headlights and tail-lights incorporating the principles described
may be regulated, by appropriate movement of the filter plate
member, to provide accurately directed or rapidly changing light
beams. These and other analogous modifications are contemplated as
coming within the scope of the invention as defined in the appended
claims.
* * * * *