US2344241A

US2344241A - Illuminated bubble level

Info

Publication number: US2344241A
Application number: US428583A
Authority: US
Inventors: Edward F Flint
Original assignee: Bausch and Lomb Inc
Current assignee: Bausch and Lomb Inc
Priority date: 1942-01-28
Filing date: 1942-01-28
Publication date: 1944-03-14
Anticipated expiration: 1961-03-14

Description

March 14, 1944. a F. FLINT ILLUMNATBD BUBBLE LBVBL.l

Filed'Ja'n'. 28, 1942 may#v EDWARD E'FLINT INVENTOR n ATTORNEY Ww H@ s lil. v

Patented Mar. 14, 1944 ILLUMINATED BUBBLE LEVEL Edward F. Flint, Rochester, N. Y., assigner to Bausch & Lomb Optical Company, Rochester, N. Y., a corporation of New York Application January 28, 1942, Serial No. 428,583

7 Claims.

This invention relates to bubble levels and more particularly it has reference to illuminated bubble levels such as are adapted for use in sextants, octants and the like.

One of the objects of my invention is to provide improved means for illuminating a bubble level. Another object is to provide a bubble level having simple yet efcient means for uniformly illuminating the bubble thereof. A further 'object is to provide a bubble level having efiicien means for providing dark-held illumination oi' the bubble. These and other objects and advantages reside in certain novel features of construction, arrangement and combination of parts as will hereinafter be more fully explained and Apointed out in the appended claims.

Fig. 4 is a plan View of the light transmitting member.

A preferred embodiment of my invention is disclosed in the drawing wherein lli indicates a housing having a central opening Il extending therethrough. An inwardly projecting boss I2 provides a seat against which is held the upper transparent member I3 by means of a threaded lock ring lli and a gasket I 5 and a lower transparent member IS is held against the boss I2 by the threaded lock ring Il and gasket I8. The transparent members may be formed of any suitable transparent material such as glass or plastic and their surfaces may be plane or formed with any desired curvature. There is thus formed between the members I3 and l5 a chamber I9 which is adapted to contain a liquid 20, such as xylol, having therein a bubble 2i. The size of the bubble may be controlled by adjustable diaphragm means contained in housing 22, although the details of such means are not shown since they form no part of the present invention.

Illumination of the bubble 2i is provided by a layer of luminescent material 23 which is applied as an annular border around the outer peripheral portion of the outer surface of member I6. The layer of material is applied directly to the surface of the member I5 so that it is in optical contact therewith. Although the layer 23 may, under certain conditions, provide suicient illumination for the bubble 2|, it may be desirable to apply an additional layer of luminescent material 24 in optical contact with the outer surface of member I3. The layers of

material

23 and 24 may comprise radium paint which is self-luminous or they may comprise phosphorescent paint which emits light following excitation by a light source.

If the layers of

material

23 and 24 comprise phosphorescent material, it is, of course, necessary to provide a source of light rays for .activating the phosphorescent material. On the other hand, if a self-luminous material, such as radium paint, is employed, it is not absolutely essential to employ a light source for exciting the material. However, a material such as radium paint usually comprises a phosphorescent substance, such as zinc sulphide, and a radioactive substance which activates the phosphorescent substance. Hence, if it is desired to increase the illumination produced by radium paint, it may be accomplished by exposing the paint, :and its constituent phosphorescent substance, to light rays from another source.

In a preferred construction, therefore, the layers of

material

23 and 24 are made of radium paint which is preferably also activated by light rays emanating from another source, such as an electric lamp 25 mounted in the housing i8. Mounted directly below the layer `2.3, and extending substantially coextensively therewith, is the annular light transmitting member 26 having a projection 21 which is frictionally held in a slot 28 in housing It so as to support the member 26 in position so that light rays from lamp 25 may enter the projection 2l and pass around the member 26. The member 2t and the projection 21, which may be either integral with or cemented onto the member 25, may be formed of any suitable light transmitting material such as quartz or a clear plastic material sold under the trade-mark Lucite. Light rays from lamp 25 enter the projection 21 and pass into the member 26 and then, by internal reflection, pass around the member 26. Due to irregularities on its surface, the member 26 will glow so that light rays will emanate from all sides thereof and so will activate the luminescent material in layer 23. In order to prevent light rays from reaching the bubble 2I directly from the lamp 25 and thereby causing uneven illumination, an opaque plug 29, made of bre or the like, is positioned in the re-entrant portion 30 formed in member 26 opposite the lamp 25.

Positioned beneath the transparent member i6 is a cylindrical member 3l having a ange 32 which is attached to the housing I0 by screws 33.

The cylinder 3| and flange 32 provide a housing for the light transmitting member 26 and since the cylinder is opaque no light rays can pass directly from the member 26 to the eye of an observer who is looking through the level. Similarly, an annular opaque shield 34 having a central aperture 35 is positioned above the layer 24 on the member I3 to prevent light rays from the

layers

23 and 24 from passing directly to an observers eye. It will be apparent, therefore, that light rays from the

luminescent layers

23 and 24 will pass directly through the transparent members I3 and I6 to illuminate the wall of the bubble 2l while some rays will be reflected by the surfaces of the members and onto the wall of the bubble. Since layer 23 is activated by the member 26, some rays from layer 23 will also strike layer 24 and tend to activate it also. In order to render the illumination more uniform, the walls adjacent the three sides of member 26 are also coated with layers of luminescent material 3@ such as zinc sulphide or the like.

It will be apparent, therefore, that light rays will strike the wall of the bubble 2| and since no light rays reach the observers eye directly from the illuminating means, the illuminated bubble 2| will appear as a luminous ring on a substantially dark background. Since the vertical dimension of chamber i9 is relatively small, the bubble 2| extends from the inner surface of one` transparent member to that of the other. Sucla a construction is advantageous in instruments such as sextants or octants, since it permits an observer to look through the bubble without the distortion which is present when a bubble is bounded on its under side by an amount of liquid. With my improved illumination system, such a bubble appears as a sharply dened luminous ring on a dark background as the wall portions of the bubble in contact with the surface of the member I3 will reflect a relatively large number of the light rays while the wall of the bubble in contact with the surface of the member I 6 will refract much of the incident light into the eye of the observer. Since the layers of

luminescent material

23 and 24 are in optical contact with the surfaces of members I3 and I6, the rays from the layers pass into the members without losses by reflection which would otherwise occur if the layers were not in optical contact with the transparent members.

From the foregoing, it will be apparent that I am able to attain the objects of my invention and provide a bubble level having improved means for illuminating the bubble. Various modications can obviously be made without departing from the spirit of my invention.

I claim:

i. A bubble level comprising a housing, upper and lower transparent members horizontally mounted in said housing, said members being vertically spaced apart to provide a bubble chamber therebetween, liquid in said chamber and a bubble in said liquid, said bubble extending from one member to the other member, and means for illuminating said bubble comprising a border of luminescent material positioned on the outer face of one of said members and means for exciting said material, said material being in optical contact with the face of said member and the light rays emitted therefrom angularly traversing said member before striking theA wall of said bubble.

2. A bubble level comprising a housing, upper and lower transparent members horizontally mounted in said housing, said members being vertically spaced apart to provide a bubble chamber, liquid in the chamber and a bubble in the liquid, means for illuminating the bubble comprising an annular layer of luminescent material positioned on each outer face of said members and extending as borders around the edges thereof, means for exciting said layers comprising annular light conducting means positioned adjacent to and substantially coextensive with the layer on one of the members and a light source adjacent said light conducting means for supplying light rays thereto, and shielding means for preventing light rays from said layers and light conducting means from directly entering the eye of an observer looking through the level.

3. In a bubble level the combination of a housing, two vertically spaced members horizontally mounted in the housing to provide a chamber, liquid in the chamber and a bubble in the liquid, one of said members being transparent, and means for illuminating the bubble comprising an annular light transmitting member positioned adjacent the outer face of the transparent member and extending around the border thereof, a light source positioned to direct light rays into said light transmitting member, and means for producing uniform illumination of the light transmitting member comprising layers of luminescent material substantially surrounding the walls of the light transmitting member.

4. A bubble level comprising a housing, two transparent members horizontally mounted in superposed relation in said housing to provide a chamber therebetween, liquid in said chamber and a bubble in the liquid, said bubble being compressed between said members, means for illuminating the bubble comprising a layer of luminescent material in optical contact with the outer face of one of the members, saidlayer extending as a border around the face or" the member with a free central opening through which the bubble may be viewed, means for exciting said material comprising annular light transmitting means positioned adjacent to and substantially coextensive with said layer and a light source adjacent said light transmitting means for supplying light rays thereto, and an opaque light shield positioned adjacent the other of said members, said shield having a central opening through which the bubble may be viewed.

5. A bubble level comprising a housing, spaced upper and lower transparent members spaced apart in said housing to provide a bubble chamber, liquid in said chamber and a bubble in the liquid, said bubble extending from one member to the other whereby light rays may pass through the members and the central portion of the bubble without traversing any substantial amount of the liquid, and means for illuminating the wall of the bubble comprising layers of luminescent material positioned around the outer portions of the outer faces of said members, means for activating said layers of material comprising a housing positioned below and substantially coextensive with the layer on the lower member and having its upper side open to the layer, the inner surfaces of the housing being coated with luminescent material, a light transmitting member in the housing and extending substantially coextensively therewith, and a light source adjacent the light transmitting member whereby light rays from said source Will excite the luminescent material.

6. A bubble level comprising a housing, two transparent members horizontally mounted in superposed relation in said housing to provide a chamber therebetween, transparent liquid in said chamber, a bubble in the liquid, means for illuminating the bubble whereby to render it visible as a luminous ring on a dark background, said means comprising an annular layer of luminescent material positioned on and extending around the peripheral portions of the outersurface of each of said members, said layers of material being in optical Contact with said surfaces, means for exciting said layers of material comprising an annular light transmitting member positioned adjacent to and extending substantially coextensive with one of said layers of material, a light source for supplying light rays to said light transmitting member, and centrally apertured shielding means for preventing light rays from the bubble illuminating means from directly reach- 20 ing the eye of an observer looking through the level.

7. A bubble level comprising a housing, two horizontally disposed transparent members carried by said housing, said members being vertically spaced apart to provide a chamber therebetween, a liquid in the chamber and a bubble in the liquid, annular layers of luminescent material carried by and in optical contact with the marginal portion of the outer faces of the transparent members, an annular member of light conducting material disposed adjacent one of said layers of luminescent material with one face thereof closely spaced from said layer, means for directing light to said annular member, and layers of luminescent material substantially surrounding the remaining faces of said light conducting member.

EDWARD F. FLINT.