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.

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.

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.