U.S. patent number 3,747,413 [Application Number 05/196,608] was granted by the patent office on 1973-07-24 for light shield for an indicating instrument.
Invention is credited to Burton M. Barrett, Buyrl A. Franks.
United States Patent |
3,747,413 |
Barrett , et al. |
July 24, 1973 |
LIGHT SHIELD FOR AN INDICATING INSTRUMENT
Abstract
A light shield for an indicating instrument including a face
plate having a forward surface in view of the user and a rearward
surface adjacent a lighted indicating element, the plate having an
elongated window therein for viewing the indicating element, the
elongated window having a cross-sectional configuration providing a
first, flat portion substantially normal to the face plate and
extending rearwardly thereof and the window having a second,
arcuate portion extending from the rearward surface of the plate
from one edge of the window, the arcuate portion intersecting the
rearward end of the flat portion, the arcuate portion being
transparent and all other portions of the plate being opaque.
Inventors: |
Barrett; Burton M. (Tulsa,
OK), Franks; Buyrl A. (Tulsa, OK) |
Family
ID: |
22726088 |
Appl.
No.: |
05/196,608 |
Filed: |
November 8, 1971 |
Current U.S.
Class: |
73/431; 359/601;
D10/70; 359/436; 367/109 |
Current CPC
Class: |
G01S
7/56 (20130101) |
Current International
Class: |
G01S
7/56 (20060101); G01d 011/24 (); G02b 027/00 () |
Field of
Search: |
;73/431 ;324/156
;350/276R ;356/256 ;240/41.4,2.1,46.53 ;340/3E,382,6,8L
;116/DIG.36,129P |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
publ. "Heath Kit Fish Spotter". Heath Co. Mail Order Cat. No.
810/71, 10/1971, (Page 90)..
|
Primary Examiner: Queisser; Richard C.
Assistant Examiner: Yasich; Daniel M.
Claims
What is claimed:
1. A light shield for a casing of an indicating instrument
comprising:
a face plate in said casing having a forward surface with indicia
thereon and in view of the user and a rearward surface adjacent a
condition responsive lighted indicating element, the face plate
including an elongated integral window means for viewing the
lighted indicating element, the elongated window means having first
and second spaced apart edges, said wondow means comprising in
cross-sectional configuration:
a first portion substantially normal to the face plate and
extending rearwardly thereof, the first portion having a forward
end and a rearward end, the forward end being coincident with said
first edge of said window; and
a second portion arcuately extending from the rearward surface of
said face plate and from said second edge of said elongated window
and interconnecting with the rearward end of said first window
portion, the arcuate second window portion being transparent and
the other portions of the plate being opaque said arcuate second
portion freely passing light rays outwardly from said indicating
element while simultaneously reflecting a substantial amount of
ambient incoming light rays into opaque portions of the plate.
2. A light shield according to claim 1 wherein said elongated
window means in said face plate is circular, said first edge being
of a larger diameter than the diameter of said second edge, said
wondow first portion forming a cylinder and said window second
portion forming a substantially truncated hemispheroid.
3. A light shield according to claim 2 including an opaque cylinder
selectively forming a portion of said window first portion.
4. A light shield for an indicating instrument comprising:
a forward opaque face plate in view of the user having an elongated
opening for viewing a condition responsive lighted indicating
element therethrough, the elongated opening having first and second
edges;
a window member rearwardly of said opening in said plate, said
window member comprising, in cross-sectional configuration:
a first portion substantially normal to the face plate, the first
portion having a forward end and a rearward end, the forward end
being coincident with said first edge of said face plate opening,
said first portion extending rearwardly of said face plate; and
a second integral arcuate portion extending from a rearward surface
of said face plate at said second edge of said window first
portion, the first portion of the window member being light
absorbing and the second portion being transparent said arcuate
second portion freely passing light rays outwardly from said
indicating element while simultaneously reflecting a substantial
amount of ambient incoming light rays into opaque portions of the
plate.
5. A light shield according to claim 4 wherein said elongated
opening in said face plate is circular, said first edge of said
opening in said face plate being of a diameter larger than the
diameter of said second edge, said window member first portion
forming a cylinder and said window member second portion forming a
substantially truncated hemispheroid.
6. A light shield according to claim 5 including an opaque cylinder
selectively forming a portion of said window member first portion.
Description
BACKGROUND, SUMMARY AND OBJECTS OF THE INVENTION
This invention is directed towards an apparatus in which a lighted
indicating element is positioned behind a plate having a window and
is intended to provide means wherein the lighted indicating element
is better visibly observed when the instrument is used in high
ambient light. As one specific example, the invention is
particularly related to a rotating disk type depth and fish
indicating apparatus. Such apparatus is sued both in day and night
fishing and consequently is frequently used in bright outdoor
light. A popular type of depth and fish indicating apparatus is
that which uses a rotated disk on which is mounted a neon bulb. The
disk rotates in synchronization with the transmission of sound
pulses in the water and the neon bulb flashes light in response to
amplified signals triggered by echoes received by a transponder
positioned in the water. In order to protect the rotating disk and
neon bulb it is customary to position them behind a plate having a
window therein, the window being in circular form. In some
instruments the windows are open so that nothing exists to obstruct
the passage of the light from the rotating neon bulb through the
window to the user. From an optical standpoint such arrangement is
very good, but it has other defects. With an open window nothing
exists to protect the rotating disk and the bulb from encountering
a physical object stuck through the window. The rotating disk and
bulb cause distracting noise which freely passes through the open
window. In addition, the open window permits dust and water to
enter the interior of the instrument. To overcome these problems
some manufacturers close the window with glass. While a sheet of
glass or clear plastic provides physical protection for the
equipment, reduces noise, and keeps out dust and water, an
additional problem is introduced. Sunlight striking the glass or
plastic is reflected back into the eyes of the viewer and
substantially decreases the ability of the viewer to observe light
from the bulb rotating behind the window. Thus, the use of a flat
plate of glass or plastic reduces the optical characteristics of
the instrument and makes it more difficult to use in bright
light.
This invention provides a light shield for an indicating
instrument, such as of the type described, which has the advantages
above enumerated for a transparent window for such instruments, but
in addition includes improved means of transmitting light from the
indicating instrument through to the user while at the same time
reducing reflection from ambient light.
It is therefore an object of this invention to provide a light
shield for an indicating instrument.
More particularly, an object of this invention is to provide a
light shield for an indicating instrument of the type having a
lighted indicating element behind a window, including improved
means of permitting light from the indicating instrument to pass
through to the user but reducing the amount of relfection from
ambient light, such as sunlight.
These general objects, as well as other and more specific objects,
will be fulfilled in the following description and claims, taken in
conjunction with the attached drawing.
DESCRIPTION OF THE VIEWS
FIG. 1 is a front view of an instrument incorporating this
invention. The instrument illustrated is the type used for
indicating depth and the presence of fish in water and is exemplary
of one type of instrument to which this invention may be
applied.
FIG. 2 is a cross-sectional view taken along the line 2--2 of FIG.
1 showing the instrument in cross-section.
FIG. 3 is an enlarged cross-sectional view of the window portion of
the light shield of this invention.
DETAILED DESCRIPTION
Referring now to the drawings, and rist to FIG. 1, an example of
one application of the invention is illustrated. A depth and fish
indicating insturment is generally dientified by numeral 10, the
instrument shown being mounted on a gimbal type bracket 12. The
instrument 10 includes a face plate 14 having an opening 16
therein. The opening 16 is shown in four segments. The opening 16
has a first edge 16A and a second, smaller diameter edge 16B.
As shown in FIG. 2, the fac plate 14 has a forward surface 14A
toward the viewer and a rearward surface 14B opposite the viewer.
Positioned behind the face plate 14 is a rotating disk 18 having a
neon bulb mounted thereon. Disk 18 is rotated by shaft 22 extending
from a motor 24. A slip ring 26 affixed to disk 18 is connected
electrically to bulb 20 by conductor 28. A brush 30 contacts slip
ring 26. The brush is connected to electronic equipment (not shown)
by which electrical energy is applied to the slip ring and thus to
bulb 20 to cause it to ignite. When the instrument is a depth and
fish indicating device, bulb 20 ignites in response to reflected
echoes from a transponder (not shown) and thus the rotational
position of disk 18 is an indication of the depth of the object
producing the echo.
The instrument described to this point is not unlike others well
known in the industry. As previously indicated opening 16 may be
completely left open to fully expose bulb 20 to the viewer,
however, such has the disadvantages above-mentioned. Others have
used a flat plate of clear plastic or glass to close opening 16,
but this produces glare. This invention is directed towards an
optical arrangement for opening 16 to permit light from bulb 20 to
fully pass therethrough to the user and which simultaneously
reduces glare of bright light, such as sunlight.
Positioned against front plate rearward surface 14B is a window
plate 32 which may be of glass or clear plastic. At opening 16 the
window plate 32 includes, in cross-sectional configuration, a first
portion 34 which is flat and substantially normal to plate 32 and
extends rearwardly thereof, the first portion having a forward end
34A which is coincident with opening edge 16A. The window plate 32
is further configured, in cross-section, by a second portion 36
which is arcuate and extends from the rearward surface of the
window plate 32. Edge 36A of arcuate portion 36 is thus coincident
with edge 16A of the opening. The other edge 36B of the arcuate
portion intersects the rearward edge 34B of the window first
portion 34. A flange 38 supports the window plate 32 against the
rearward surface of the face plate 14.
The window plate first portion 34 is opaque, or at least the
surface 34C thereof facing arcuate portion 36 is opaque. This may
be accomplished such as by painting surface 34C with dark
paint.
It can be seen that light from bulb 32 may freely pass through the
transparent arcuate portion 36 to the viewer. Ambient light, such
as sunlight, passing through opening 16, encounters the arcuate
surface of window second portion 36 and is reflected downwardly
against surface 34C which, being opaque, absorbs rather than
reflects the light rays striking it. In this way, much of the
ambient light striking the opening 16 is prevented from being
reflected back to the eyes of the viewer while at the same time
light from bulb 20 is permitted to pass freely.
FIG. 3 shows an alternate embodiment of the invention. As
previously indicated, the window first portion 34 must be opaque
(or at least surface 34C must be opaque). In the best arrangement
the window plate 32 is an integral piece so that the window first
portion 34 and the second portion 36 are formed of the same
material. Since the window second portion 36 must be transparent,
it is difficult and expensive to manufacture the plate wherein
opaque and transparent portions are contiguous and integral to each
other. To overcome this problem an opaque cylinder 40 is positioned
over the window first portion 34. Since cylinder 40 is a separate
item it can easily be manufactured of opaque plastic or metal. Thus
the entire window plate 32 may be of clear material, such as clear
plastic. Opaque cylinder 40 absorbs the light reflected from the
arcuate portion 36. Dotted line 42 illustrates the direction
ambient light, such as sunlight takes, in striking arcuate portion
36. It is reflected to opaque surface 34C, or the opaque cylinder
40, and is absorbed.
In the illustrated arrangement of the invention face plate 14 and
window plate 32 are shown as separate items. It can be seen that in
the simplest embodiment only a window plate 32 is required and all
portions of the window plate as described will be opaque except the
window arcuate portion 36 which must be transparent.
The invention has been described as it particularly relates to a
type of instrument having a rotating disk, but the principles of
the invention are adaptable to any type of instrument utilizing a
light indicating element. Opening 16 may be linear or any other
configuration, rathr than circular as shown.
While the invention has been described with a certain degree of
particularity it is manifest that many changes may be made in the
details of construction and in the arrangement of the components
without departing from the spirit and scope of this disclosure. It
is understood that the invention is not limited to the embodiment
illustrated herein for purposes of exemplification, but is to be
limited only by the scope of the attached claim or claims,
including the full range of equivalency to which each element
thereof is entitled.
* * * * *