WO2009136947A1

WO2009136947A1 - Level

Info

Publication number: WO2009136947A1
Application number: PCT/US2008/063317
Authority: WO
Inventors: William L. Litchfield
Original assignee: Litchfield William L
Priority date: 2008-05-09
Filing date: 2008-05-09
Publication date: 2009-11-12
Also published as: WO2009137692A1

Abstract

A level comprising: a frame having at least one plane measuring surface and at least one side at right angles to each other and designed to retain a bubble level vial so that the bubble level vial is visible from the side; a bubble level vial affixed within the frame so that its long axis is parallel to the plane measuring surface; and level indicating indicia on the side. A level vial useful in construction of such levels comprises; a transparent unmarked container; a fluid incompletely filling the container; and a bubble of air within the container.

Description

Level Technical Field

The present invention relates to the field of levels and more particularly to the field of spirit levels.

Background Art

Most commonly, spirit levels are employed to indicate how horizontal (level) or how vertical (plumb) a member or surface is. Different types of spirit levels are used by carpenters, stone masons, bricklayers, other building trades workers, surveyors, millwrights and other metalworkers, and serious videographers.

The first spirit levels had two banana-shaped curved glass vials at each viewing point and were much more complicated to use. In the 1920s, Henry Ziemann, the founder of Empire Level, invented the modern level with a single vial. These vials, common on most ordinary levels today, feature a slightly curved glass tube with scribe lines at right angles to the long axis of the tube. The tube is incompletely filled with a liquid, usually yellow-colored ethanol, leaving a bubble. Ethanol is used because of its low freezing point, -114°C, which prevents it from freezing in cold weather.

A large number of inventors have tried to improve on the construction of levels.

US Patent No.2,282,166 discloses a plumb and level made in sections. The invention primarily concerns the mechanism that joins the sections together. No particular mention is made of where the scribe lines are located.

US Patent No. 2,535,791 discloses a level with a magnetic securing means. No particular mention is made of where the scribe lines are located.

US Patent No.3,104,477 discloses an extendible level. No particular mention is made of where the scribe lines are located but Figure 2 indicates that they are on the level vials.

US Patent No. 3,956,934 discloses a liquid level indicator for a container of pressurized liquid. US Patent No. 4,124,940 discloses a particular method of assembling a level. No particular mention is made of where the scribe lines are located but Figure 1 indicates that they are on the level vials.

US Patent No. 4,979,310 discloses a particular level construction which eliminates the need for painting and eliminates problems resulting from shrinkage of plastic covers. No particular mention is made of where the scribe lines are located but Figure 1 indicates that they are on the level vials.

US Patent No. 5,199,177 discloses the construction of a lighted level. No particular mention is made of where the scribe lines are located but Figure 1 indicates that they are on the level vials.

US Patent No. 5,412,876 discloses a protective end cap for a spirit level. No particular mention is made of where the scribe lines are located but Figure 1 indicates that they are on the level vials.

US Patent No. 5,479,717 discloses construction of a slip resistant level. No particular mention is made of where the scribe lines are located.

US Patent No. 5,575,073 discloses an apparatus for setting a level plane which includes a spirit level. While the vials are mentioned no particular mention is made of the scribe marks.

US Patent No. 508,762 discloses a spirit level with laterally adjustable end sections.

US Patent No. 6,324,767 discloses a sight level.

US Patent No. 6,381 ,859 discloses a particular construction for a level. Figures 1 and 2 show the scribe marks on the bubble level vials.

US Patent No. 6,434,842 discloses a sanding and rasping level. This device is a level with sandpaper on one surface. The level vials are described as "typical" and Figures 1 and 5 show scribe lines on the longitudinal vial.

US Patent No. 6,577,388 discloses a laser level including bubble levels. No particular mention is made of where the scribe marks are located. US Patent No. 6,915,586 discloses a box level with hang openings. No particular mention is made of where the scribe lines are located but Figures 1 and 2 indicate that they are on the level vials.

US Patent No. 6,988,320 discloses a particular level construction. Holes for insertion of level vials are mentioned.

US Patent No. 6,988,406 discloses a system and method for detection of liquid level in a tank.

US Patent No. 7,150,106 discloses a level with removable end caps and holes for insertion of level vials. The specification includes no description of the level vials.

US Patent No. 7,204,029 discloses a particular level construction including structures for receiving magnets and level vials covered by lenses. The level vials are described as having "spaced line indicators of usual type". See column 7, lines 3-6.

US Patent No. 981 ,434 discloses a float gage.

US Patent No. D388,719 discloses a spirit level.

US Patent No. D457,446 discloses a laser level. Scribe marks are not visible.

US Patent No. D479,139 discloses a level. Scribe marks appear to be on the level vials.

US Patent No. D503,635 discloses a spirit level. Scribe marks are visible on the level vials.

US Patent No. D509,761 discloses a laser level but level vials are not readily discernible.

US Patent No. D525,543 discloses a spirit level with scribe marks clearly on the level vials.

US Patent No. D528,022 discloses a laser measuring device with a circular bubble level having a circular scribe mark on its top.

US Patent No. D533,093 discloses a laser measuring device. Figures 3, 5 and 6 show a bubble level having several scribe marks.

US Patent No. D535,576 discloses an electronic spirit level with level vials having scribe marks. US Patents Nos. 6,675,490 and 6,792,686 disclose a construction of a level using a thin wall construction. The construction includes horizontal and vertical vial assemblies but no particular mention is made of where the scribe lines are located but in Figure 10, they are shown on the vial.

US Patent No. 4,164,077 discloses level indicating devices wherein at least a side portion of a bubble cavity is defined by a reflecting surface having at least a linear cross section lying generally in a plane aligned with or paralleling a light source and a bubble image observer (i.e. person or sensor).

US Patent No. 2,635,350 discloses a leveling device comprising an elongated base having a pair of longitudinal side legs disposed in inverted V relationship and a top defined by the apex of the V, the legs having co-planar fiat level checking faces at the bottom edges 15 thereof spaced apart co-planar flat level checking faces at the inner surface of each leg and flat level checking faces adjacent the outer sides of the legs at right angles to the inner faces and the top including a raised handle portion ex- 20 tending longitudinally from, adjacent one end of the base to the raid-region thereof, the outer surface of the handle tapering toward the one end of the base.

One of the most critical aspects of manufacturing levels is to ensure that the long axis of the vial is parallel to the measuring surface of the level. Another is keep the long axis of the vial and the measuring surface parallel throughout long use and possible abuse of the level.

Hopkins Manufacturing Corporation of Emporia, Kansas, sells a model 09515 level vial that is roughly square and can be used for determining plumb and level of members and level of surfaces. It is made from injection molded plastic so it is not a very precision instrument but very inexpensive to produce.

Stabila, Inc. of Germany sells extremely high precision and expensive levels. Their levels incorporate very high tech methods of clamping the vial into the level frame so that the long axis of the vial is precisely aligned with the measuring surface and so that the orientation of the vial cannot be easily changed during use.

However, all the above listed inventions and improvements utilize vial technology that was developed in the 1920's. There has been no improvement in vial technology since. Development of a new type of vial which can enable manufacture of high precision levels more inexpensively and with a greater tolerance to abuse represents a great improvement in the field of level manufacturing and satisfies a long felt need of carpenters, stone masons, bricklayers, surveyors, millwrights and others for levels in which they can intuitively place greater trust.

Disclosure of Invention

This invention is a level comprising:

a frame having at least one plane measuring surface and at least one side at right angles to each other and designed to retain a bubble level vial so that the bubble level vial is visible from the side;

an unmarked bubble level vial (i.e. one having no scribe marks) affixed within the frame so that its long axis is parallel to the plane measuring surface; and

level indicating indicia (scribe marks) on the side.

Such a level may be fabricated by:

fabricating a frame having at least one plane measuring surface and at least one side at right angles to each other and designed to retain a bubble level vial so that the bubble level vial is visible from the side;

obtaining an unmarked bubble level vial (i.e. one having no scribe marks)having a long axis;

affixing the bubble level within the frame so that its long axis is parallel to the plane measuring surface; and

applying level indicating indicia (scribe marks) to the side.

Such a level may be alternatively fabricated by:

fabricating a first rectangular frame of clear material, having two plane measuring surfaces, a mating side and a plane side; the plane measuring surfaces being parallel to each other and at right angles to the mating side and the plane side; forming a half-cavity in the mating side; the half-cavity having a long axis parallel to the plane surfaces;

fabricating a second rectangular frame; the second rectangular frame being a mirror image of the first rectangular frame;

fastening the mating sides of the first and second frame together to create a frame including a sealed bubble level cavity;

incompletely filling the sealed bubble level cavity with fluid so that a bubble of air remains; and

applying level indicia (scribe marks) to at least one of the plane sides.

Such a level may alternately be fabricated by:

fabricating a first rectangular frame of clear material, having two plane measuring surfaces, a mating side and a plane side; the plane measuring surfaces being parallel to each other and at right angles to the mating side and the plane side;

forming at least one half-cavity in the mating side; the half-cavity having a long axis parallel to the plane surfaces;

fabricating a second rectangular frame identical in size to the first rectangular frame; the second rectangular frame having two plane measuring surfaces, a mating side and a plane side; the plane measuring surfaces being at right angles to the mating side and the plane side;

fastening the mating sides of the first and second frame together to create a frame including a sealed bubble level half-cavity;

incompletely filling the sealed bubble level half-cavity with fluid so that a bubble of air remains; and

applying level indicia (scribe marks) to at least one of the plane sides.

Since the frames may be made of a soft material, such as a clear plastic, the plane measuring surfaces may be clad with a harder material such as metal. A level vial useful in construction of such levels comprises;

a transparent unmarked container (i.e. one having no scribe marks);

a fluid incompletely filling the container; and

a bubble of air within the container.

Such level vials are made by:

providing a transparent unmarked container (i.e. one having no scribe marks); and

incompletely filling the container with fluid whereby a bubble of air remains within the container.

The containers could be tubular, circular, dome shaped, square or rectangular with slightly curved sides.

An appreciation of the other aims and objectives of the present invention and a more complete and comprehensive understanding of it may be achieved by referring to the accompanying drawings and studying the following description of the best mode of carrying out the invention.

Brief Description of Drawings

Figure 1 is a partial side elevational view of a typical prior art level.

Figure 2 is a cross sectional view along the lines 2-2 of Figure 1.

Figure 3 is a partial side elevational view of a first embodiment of a level in accordance with this invention.

Figure 4 is a cross sectional view along the lines 4-4 of Figure 3.

Figure 5 is a perspective view of a frame component for a second embodiment of a level in accordance with this invention.

Figure 6 is a cross sectional view along the lines 6-6 of Figure 5. Figure 7 is a side elevational view of the second embodiment of a level in accordance with this invention.

Figure 7A is a side elevational view of a variation of the second embodiment of a level in accordance with this invention.

Figure 7B is a top view of the variation of the second embodiment of a level in accordance with this invention shown in Figure 7A. The bottom view is a mirror image of this view.

Figure 8 is a cross sectional view along the lines 8-8 of Figure 7.

Figure 9 is a cross sectional view of a third embodiment of a level in accordance with this invention.

Figure 10 is a perspective view of a fourth embodiment of a level in accordance with this invention.

Figure 11 is a cross sectional view along the lines 11 -11 of Figure 10.

Figure 12 illustrates the concept of this invention applied to a telescope.

Fgure 13 illustrates the concept of this invention applied to a table with telescoping legs.

Best Mode for Carrying Out Invention

Figures 1 and 2 illustrate a portion of a typical prior art level 10. Such a level 10 has a frame 14 which has a top plane surface 18, a bottom plane surface 22 and an intermediate web 26. The top and bottom plane surfaces are parallel to each other. Retained within the web 26 is a bubble level vial 30. A variety of different methods are used to retain the level vial 30 within the web 26 but the retaining ring 34 usually protrudes from the web 26. In the portion illustrated in Figures 1 and 2 the level vial 30 is essentially tubular and it is secured within the web 26 so that its longitudinal axis 38 is parallel to the plane surfaces 18, 22. The bubble level vial 30 typically comprises a transparent tube with slightly curved sides 42, preferably made of glass or plastic, which is incompletely filled with a fluid 46 so that a bubble of air 50 remains. The outside surface of the vial 30 is scribed with scribe marks 54, at right angles to the longitudinal axis 38 of the vial 30. The quantity of fluid 46 in the vial 30, and thus the size of the bubble 50, and the distance between the scribe marks 54 are adjusted so the length of the bubble 50 is just about the same size as the distance between the scribe marks 54 when the level 10 and the vial 30 are horizontal.

Although not illustrated, those familiar with the art to which this invention pertains will recognize that another vial 30 may be retained within the web 26 with a longitudinal axis that is at right angles to the top and bottom plane surfaces 18, 22. Such a vial 30 is used to determine plumb.

Further, another vial 30 may be retained within the web 26 with a longitudinal axis that is at 45

⁰ to the one of the plane surfaces 18 or 22. Such a vial 30 is used to determine how close a surface is to 45 °from level or plumb. Those familiar with the art to which this invention pertains will recognize that bubble level vials must have a constant radius which is centered at the axis to be leveled. Those familiar with manufacturing techniques will also recognize that it is impossible to fabricate items exactly. Every dimension of an item must be fabricated to a tolerance. Thus the when the terms right angle, parallel, etc. are used in this specification it will be understood that this means within manufacturing tolerances.

Figures 3 and 4 illustrate a first embodiment 100 of a level in accordance with this invention. This embodiment 100 has a frame 104 which has a top plane surface 108, a bottom plane surface 112 and an intermediate web 116. The top and bottom plane surfaces 108, 112 are parallel to each other. Retained within the web 116 is a bubble level vial 120. A variety of different methods are used to retain the level vial 120 within the web 116 but the retention mechanism is completely within the confines of the web 120. Furthermore, the center section, A, of the web 116 is clear to permit viewing of the level vial 120. In the portion illustrated in Figures 3 and 4 the level vial 120 is essentially tubular and it is secured within the web 116 so that its longitudinal axis 124 is parallel to the plane surfaces 108, 112. The bubble level vial 120 typically comprises a transparent tube 128 with slightly curved sides, preferably made of glass or plastic, which is incompletely filled with a fluid 132 so that a bubble of air 136 remains. The outside surface of the vial 120 has no scribe marks. Instead, scribe marks 140 are applied on the surface 144 of the web 116. The scribe marks 140 may be applied by any convenient method such as printing, engraving, silk screening, etc. The quantity of fluid 132 in the vial 120, and thus the size of the bubble 136, and the distance between the scribe marks 140 are adjusted so the length of the bubble 136 is just about the same size as the distance between the scribe marks 140 when the level 100 and the vial 120 are horizontal. Although not illustrated, those familiar with the art to which this invention pertains will recognize that another vial 120 may be retained within the web 116 with a longitudinal axis that is at right angles to the top and bottom plane surfaces 108, 112. Further, another vial 120 may be retained within the web 116 with a longitudinal axis that is at 45 ° to one of the plane surfaces 108 or 112.

In addition, it would be best to inscribe the scribe marks 140 on both sides 144 of the web 116. In this way, the ends of the bubble 136 and the scribe marks 140 on both sides 144 of the web 116 can be visually lined up to avoid parallax error. In fact inscribing the scribe marks 140 on both sides 140 of the web 116 enables elimination of parallax error better than in the prior art levels 10. This is because three lines (two scribe lines and the meniscus) at a distance from each other must be lined up rather than three lines that are very close to each other.

Figures 5 and 6 illustrate a frame component 204 for a second embodiment 200 of a level in accordance with this invention. This component 204 is made of a rectangular cylinder of clear material into which one or more elongated half-cavities 208 have been machined. Shown on Figures 5 and 6 are lines showing the longitudinal axes of the half-cavities 208. One 212 is a parallel to the measuring surfaces 216, one 220 is at right angles to the measuring surfaces 216 and one 224 is at 45 ° to one measuring surface 216.

Figure 7 and 8 illustrate the completely assembled second embodiment 200. In this embodiment 200, two frame components 204, which are mirror images of each other, are fastened together. In this way, one or more sealed, complete cavities 228 are formed. Fastening may be accomplished by any convenient means such as adhesive bonding, welding or bolting. The cavities 228 are then incompletely filled with the proper amount of fluid 132, thus creating a bubble of air 236 and scribe marks 240 are placed on one or both sides 244 of the completely assembled level 200.

Figures 7A and 7B illustrate a variation 200a of the second embodiment 200. In this variation 200a the vial 228 is visible from the top 274 of the level 200a and the scribe marks 240 continue over the top 274. Thus level can be determined if it is not possible to place the eye to the side of the vial 228. In like manner scribe marks can be continued over the bottom 270 of the level so that level can also be determined from underneath. Figure 9 is a cross sectional view of a third embodiment 300 of a level in accordance with this invention. In this embodiment 300, one frame component 204 is fastened to another block of transparent material 250 of the same size. In this way, one or more sealed half-cavities 254 are formed. Fastening may be accomplished by any convenient means such as adhesive bonding, welding or bolting. The half-cavities 254 are then incompletely filled with the proper amount of fluid 132, leaving a bubble of air 236, and scribe marks 240 are placed on one or both sides 244 of the completely assembled level 300.

Figures 10 and 11 illustrate a fourth embodiment 400 of a level in accordance with this invention. This embodiment 400 is made of a rectangle of clear material 404 into which an essentially square half-cavity 408 with slightly curved sides has been machined. This frame component 404 is fastened to another block of transparent material 412 of the same size. In this way, a sealed, rectangular half-cavity 408 is formed. Fastening may be accomplished by any convenient means such as adhesive bonding, welding or bolting. The half-cavity 408 is then incompletely filled with the proper amount of fluid 132, leaving a bubble of air 420, and scribe marks 424 are placed on one or both sides 428 of the completely assembled level 400. Plumb and vertical scribe marks 424 are placed on the level parallel to the measuring surfaces 432, 436. The fourth embodiment 400 is analogous to the third embodiment 300 described above. A fifth embodiment (not illustrated), analogous to the second embodiment 200 described above, using two rectangles 404 with essentially square half-cavities 408, fastened to each other can also be made.

In any of the second 200, 200a, third 300, fourth 400 and fifth embodiments each cavity 228 or half-cavity 254, 408 may be filled by machining or otherwise providing a bore 258 which connects the cavity 228 or half-cavity 254, 408 with the outside. Fluid 132 can then be introduced through this tube 258 and the bore 258 sealed by any convenient means, such as by plugging with a rod or dowel 262 of the same clear material. See Figures 8, 9 and 11.

Figures 4 and 8 illustrate another variation on all embodiments of this invention. This invention will preferably be made of a clear plastic, such as acrylic. It is well known that plastics are soft and easily scratched and dented. To prevent this, a metal or wooden cladding 148 may be fastened to the top and bottom plane surfaces. Further, in the second through fifth embodiments the sides of the half-cavities and cavities are slightly curved.

The concept of this invention can be applied to many different pieces of equipment. For example Figure 12 illustrates the concept of this invention applied to a telescope 500. The telescope 500 has a level vial 504 attached so it that is viewable through a clear window 508 having one or two sides 512. The vial 504 is attached so that its long axis 506 is parallel to a long axis 520 of the telescope 500. Thus, when the bubble 516 is centered, this axis 506 and the longitudinal axis 520 are level. The window 508 has scribe marks 524 on it on one or both sides. When the bubble 516 is centered between the scribe marks 524, the axis 520 and telescope 500 are level. In this version the axis 520 functions as a virtual plane measuring surface.

As another example, Figure 13 illustrates the concept of this invention applied to a table 550 with telescoping legs 554. The table 550 has a level vial 562 attached to it that is viewable through a clear window 566 having one or two sides 570. The vial 562 is attached so that its long axis 564 is parallel to a long axis 582 of the table 550. Thus, when the bubble 562 is centered, this axis 564 and the longitudinal axis 582 are level. The window 566 has scribe marks 586 on it on one or both sides 570. When the bubble 574 is centered between the scribe marks 586, the table 550 and axis are level. In this version the axis 582 functions as a virtual plane measuring surface.

The level has been described with reference to several embodiments. However, it should be obvious to those skilled in the art to which this invention pertains that other modifications and enhancements can be made without departing from the spirit and scope of the claims that follow.

Claims

1. A level comprising:

a) a frame having: at least one plane measuring surface and at least one side at right angles to each other; said frame designed to retain a bubble level vial so that said bubble level vial is visible from said side;

b) an unmarked bubble level vial having a long axis, affixed within said frame so that its long axis is parallel to said plane measuring surface; and

c) level indicating indicia on said side.

2. A level as claimed in claim 1 further comprising a cladding on said plane measuring surface.

3. A method of fabricating a level comprising the steps of:

a) fabricating a frame having; at least one plane measuring surface and at least one side at right angles to each other; said frame designed to retain a bubble level vial so that said bubble level vial is visible from said side;

b) obtaining an unmarked bubble level vial having a long axis;

c) affixing said bubble level vial within said frame so that its long axis is parallel to said plane measuring surface; and

d) applying level indicating indicia to said side.

4. A level as claimed in claim 3 further comprising the step of fastening a cladding to said plane measuring surface.

5. A method of fabricating a level comprising the steps of:

a) fabricating a first rectangular frame of clear material, having two plane measuring surfaces, a mating side and a plane side; said plane measuring surfaces being parallel to each other and at right angles to said mating side and said plane side; b) forming a half-cavity in said mating side; said half-cavity having a long axis parallel to said plane surfaces;

c) fabricating a second rectangular frame; said second rectangular frame being a mirror image of said first rectangular frame;

d) fastening said mating sides of said first and second frame together to create a frame including a sealed bubble level cavity;

e) incompletely filling said sealed bubble level cavity with fluid so that a bubble of air remains; and

f) applying level indicia to one of said plane sides.

6. A method of fabricating a level as claimed in claim 5 further comprising the step of applying level indicia to the other of said plane sides.

7. A method of fabricating a level as claimed in claim 5 further comprising the step of applying level indicia to one pair of adjacent plane measuring surfaces.

8. A method of fabricating a level as claimed in claim 5 further comprising the step of applying level indicia to the other pair of adjacent plane measuring surfaces.

9. A method of fabricating a level as claimed in claim 5 further comprising the step of cladding said plane measuring surfaces.

10. A method of fabricating a level comprising the steps of:

a) fabricating a first rectangular frame of clear material, having two plane measuring surfaces, a mating side and a plane side; said plane measuring surfaces being parallel to each other and at right angles to said mating side and said plane side;

b) forming at least one half-cavity in said mating side; said half-cavity having a long axis parallel to said plane surfaces;

c) fabricating a second rectangular frame identical in size to said first rectangular frame; said second rectangular frame having two plane measuring surfaces, a mating side and a plane side; said plane measuring surfaces being at right angles to said mating side and said plane side;

d) fastening said mating sides of said first and second frame together to create a frame including a sealed bubble level half-cavity;

e) incompletely filling said sealed bubble level half-cavity with fluid so that a bubble of air remains; and

f) applying level indicia one of said plane sides.

11. A method of fabricating a level as claimed in claim 10 further comprising the step of applying level indicia to the other of said plane sides.

12. A method of fabricating a level as claimed in claim 10 further comprising the step of applying level indicia to one pair of adjacent plane measuring surfaces.

13. A method of fabricating a level as claimed in claim 10 further comprising the step of applying level indicia to the other pair of adjacent plane measuring surfaces.

14. A method of fabricating a level as claimed in claim 10 further comprising the step of cladding said plane measuring surfaces.

15.A level vial comprising;

a) a transparent unmarked container;

b) a fluid incompletely filling said container; and

c) a bubble of air within said container.

16.A level vial as claimed in claim 9 in which said container is tubular with curved sides.

17.A level vial as claimed in claim 9 in which said container is rectangular with curved sides.

18.A method of fabricating a level vial comprising the steps of:

a) providing a transparent unmarked container; and b) incompletely filling said container with fluid whereby a bubble of air remains within said container.

19.A method of fabricating a level vial as claimed in claim 12 in which said container is tubular with curved sides.

20. A method of fabricating a level vial as claimed in claim 12 in which said container is rectangular with curved sides.