Geometrical instruments – Indicator of direction of force traversing natural media – Level or plumb – terrestrial gravitation responsive
Reexamination Certificate
1999-03-03
2001-04-03
Gibson, Randy W. (Department: 2859)
Geometrical instruments
Indicator of direction of force traversing natural media
Level or plumb, terrestrial gravitation responsive
Reexamination Certificate
active
06209211
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to spirit levels, and particularly to a spirit level with multiple bubble vials, each bubble vial having a different angular orientation, such that a range of angular orientations of surfaces may be set or plumbed.
BACKGROUND OF THE INVENTION
Spirit levels, also called bubble levels, are well known instruments used for setting horizontal or vertical surfaces. The level includes a sealed vial containing an air bubble floating in a liquid. The spirit level has a level face which is placed against the surface to set or plumbed. The particular surface is considered horizontal or vertical when the air bubble rests between predetermined graduated marks in the vial.
In general in the prior art, one single spirit level is dedicated to setting or plumbing a horizontal surface, a vertical surface and perhaps a surface tilted 45° from the vertical. In certain applications, however, it is important to obtain a slightly non-horizontal or non-vertical surface. For example, in setting drainage or sewage pipes, the pipe must be tilted a few degrees from the horizontal in order to ensure proper drainage. Prior art spirit levels are inadequate for setting such surfaces. The proper angle is usually set by rough estimation with a spirit level meant for setting horizontal surfaces, or if accuracy is required, is set with specially made equipment.
SUMMARY OF THE INVENTION
The present invention seeks to provide an improved spirit level comprising multiple bubble vials. It is noted that throughout the specification and claims the term bubble vial refers to a vessel in which a liquid and bubble are contained, and this is to be distinguished from a bubble vial housing which refers to any type of structure used as an intermediary to mount the bubble vial in the body of the spirit level.
Each bubble vial has a different angular orientation, such that a range of angular orientations of surfaces may be set or plumbed with the same level face. For example, surfaces tilted 0°, 1° or 2° from the vertical/horizontal may be plumbed/set.
In a preferred embodiment of the present invention, the bubble vial housing of each bubble vial has substantially the same angular orientation with respect to the level face, despite the fact that each bubble vial has a different angular orientation with respect to the level face. “Angular orientation of the bubble vial/bubble vial housing” is herein defined as the angular orientation of a longitudinal axis of the bubble vial/bubble vial housing with respect to the level face. The term “longitudinal axis” applies to the axis along the longest dimension of non-circular bubble vials/bubble vial housings. This feature distinguishes the present invention from the spirit levels of the prior art wherein the 0° bubble vial and bubble vial housing have one angular orientation with respect to the single level face, which is different than the annular orientation for the 90° bubble vial and bubble vial housing, and so forth. In contrast, since the present invention is concerned with small angular ranges, each bubble vial housing maintains substantially the same angular orientation with respect to the level face, while each bubble vial has a different angular orientation with respect to the level face.
There is thus provided in accordance with a preferred embodiment of the present invention a spirit level including a body having a level face for setting a surface, and a plurality of bubble vials each mounted in a bubble vial housing, the bubble vial housings being mounted in the body, each the bubble vial having a longitudinal axis, called a vial axis, and each the bubble vial housing having a longitudinal axis, called a housing axis, wherein an angular orientation of the vial axis of one the bubble vials with respect to the level face is different than an angular orientation of the vial axis of another the bubble vial with respect to the level face, the difference in angular orientation being in the range of 0°-30°. Other possible ranges include 0°-20°, 0°-10°, 0°-5°, 0°-3°, 0°-2°, or 0°-1°, for example.
In accordance with a preferred embodiment of the present invention an angular orientation of the housing axes of all the bubble vial housings with respect to the level face is generally equal.
Further in accordance with a preferred embodiment of the present invention an angular orientation of the housing axes of all the bubble vial housings with respect to the level face is substantially equal.
Still further in accordance with a preferred embodiment of the present invention the bubble level housings are mounted generally parallel to the level face. Additionally in accordance with a preferred embodiment of the present invention the bubble level housings are mounted along the level face.
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Gibson Randy W.
Kapro Industries Ltd.
Ladas & Parry
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