Patent Description:
The present invention relates generally to the field of tools. The present invention relates specifically to a tool, such as a level, a spirit level, a digital level, etc., that is extendable such that its length may be adjusted as needed by a user. Levels, such as spirit levels, are used to determine the levelness of a structure, surface or workpiece. In use, the level is placed on or in contact with a surface to be measured, and the user views the location of a bubble within a vial (or other levelness indicator such as a digital display) relative to markings that indicate the levelness of the structure, surface or workpiece.

<CIT> discloses a carpenter's level extendable from a length of <NUM> inches to a length of <NUM> inches in six-inch increments. The level includes an I-beam shaped base section with right and left extension members slidably mounted thereon. Said extension members engage either side of the base at tracks formed by the side extensions of the I. The extension sections are independently movable relative to the base and to each other, and a locking mechanism is carried by each extension section to lock said section against lateral movement in a predetermined extension position. Each extension section carries a conventional tubular spirit level vial in an aperture and a third vial is centrally located in an aperture through the base section. Each extension section and the base section also has apertures therethrough spaced on, for example, six-inch centers for visible observation of each vial whether the members are extended or collapsed. A longitudinal ridge is provided on the upper and lower surfaces of the base section, the surface of which, with the upper and lower surfaces of the extension section, forms a continuous levelling and plumbing surface.

One embodiment of the invention relates to a level configured to have an adjustable longitudinal length. The level comprises a frame slidably engaged with an extension, such as a movable body member. The level comprises a braking mechanism that frictionally resists movement between the frame and the extension.

The level frame comprises a longitudinal axis delimited by a fixed end and an open end. The frame and the extension have bottom surfaces that are coplanar with each other, and an adjustable end of the extension slidably extends past the open end of the frame.

Broadly speaking, the level can be placed in variety different configurations: a fully- retracted configuration, a fully-extended configuration and a large number of partially-extended configurations as may be selected by the user. In the fully- retracted configuration, the extension is fully retracted and the distance between the frame's fixed end and the extension's adjustable end is minimized. In the fully-extended configuration, the extension is fully extended from the frame to maximize the distance between the frame's fixed end and the extension's adjustable end. In the partially-extended configuration, the extension, as should be expected, is partially extended from the frame (i.e., partway between the fully-extended configuration and the fully- retracted configuration).

In various embodiments, the level comprises one or more bushings that comprise a spring exerting a force between the frame and the extension. The extension comprises a cavity that extends along the longitudinal axis and engages around one or more protrusions from the frame, such as by a dovetail fit. The bushing spring exerts a force that pushes the extension and the frame away from each other.

In various embodiments, the level comprises a braking mechanism that controls the ease with which the extension and the frame can be slid along each other. The braking mechanism engages with the extension, which allows a user to adjustably control a frictional force needed to axially adjust the extension with respect to the frame.

In various embodiments, the vials are set in front of a color-contrasting background to facilitate the readability of the vials. For example, in one or more embodiments the vials includes a blue liquid and the background of the vial holder is white.

Additional features and advantages will be set forth in the detailed description which follows, and, in part, will be readily apparent to those skilled in the art from the description or recognized by practicing the embodiments as described in the written description and claims hereof, as well as the appended drawings. It is to be understood that both the foregoing general description and the following detailed description are exemplary.

The accompanying drawings are included to provide a further understanding and are incorporated in and constitute a part of this specification. The drawings illustrate one or more embodiments and together with the description serve to explain principles and operation of the various embodiments.

Referring generally to the figures, various embodiments of a level, such as a spirit level, are shown. In general, levels have one or more precision surfaces used for engagement with a workpiece during leveling. The level discussed herein is designed such that the level's length can be adjusted by the user as needed for various leveling applications. As will be discussed in more detail below, Applicant has developed a variety of innovative mechanisms for an extendable level that provide for smooth and stable relative motion between level sections, adjustable level of friction between level sections, a high visibility vial surround arrangement particularly suited to an extendable level design and/or an end cap design particularly suited to an extendable level design. In general, the levels discussed herein are extendable and are configured to engage a workpiece with at least one extendable and continuous working surface. As used herein an extendable continuous working surface is one that is both length adjustable and that defines a contiguous, coplanar working surface that extends uninterrupted between opposing first and second ends of the level.

In a specific embodiment, Applicant's level provides a level with a primary body and an extension piece that have coplanar upper and lower working surfaces. A benefit of this configuration is that, independent of length the level has been adjusted to, the level provides one or more continuous coplanar working surface to engage with the desired surface of a workpiece.

In various embodiments, the extension is moved along level frame via a longitudinal axis to expand or contract the length of the level. The extension comprises an internal cavity that extends along its length and engages around one or more protrusions from the frame. The interface between the extension and the frame is further affected by two bushings. One bushing is coupled to the frame and comprises a spring that is biased against the extension, exerting a force between the frame and the extension. The other bushing is coupled to the extension and comprises a spring that is biased against the frame, also exerting a force between the extension and the frame.

In various embodiments, the level comprises a braking mechanism that can be adjusted to control an amount of friction that resists axial movement between the extension and the frame. This braking mechanism is adjustable by the user of the level which allows the user to control the amount of resistance to axial movement provided by the braking mechanism. In specific embodiments, the braking mechanism comprises a screw that engages with a threaded brake that exerts an adjustable amount of lateral force against the extension.

Referring to <FIG>, an extendable, expandable or continuous edge length adjustable level, such as level <NUM>, is shown according to an exemplary embodiment. In general, level <NUM> is extendable in that its length is reversibly adjustable allowing the user to increase and decrease the length of level <NUM> as may be needed for various uses. In general, to expand level <NUM>, slidable body member <NUM> is moved along frame <NUM> away from fixed end <NUM> along longitudinal axis <NUM>, and to retract/collapse level <NUM>, slidable body member <NUM> is moved along frame <NUM> toward fixed end <NUM>. In some embodiments, slidable body member <NUM> is sized such that its entire length fits between fixed end <NUM> and open end <NUM> of frame <NUM> when in the collapsed position.

Level <NUM> includes one or more level indicators, such as level vials <NUM> (e.g., bubble vials, spirit vials, etc.), which are supported by frame <NUM> in the appropriate orientation relative to surfaces <NUM> and/or <NUM> in order for the vials to indicate the angle, levelness, degree of plumb, etc. of the corresponding surface of a workpiece, as needed for a particular level design or level type.

Unlike a standard fixed length level with a single integral body that defines the working surfaces, one difficulty with expandable levels is the ability to maintain the coplanar nature of the working surfaces on opposing outer body portions, while at the same time providing a robust and easy to use extendable body design and locking/braking mechanism. As will be discussed in more detail below, the braking mechanism and/or frame designs discussed here are believed to address these potential design issues.

Referring to <FIG>, level <NUM> includes a rear bushing <NUM> and a front bushing <NUM>. In general, rear bushing <NUM> and front bushing <NUM> provide robust and low friction sliding contact surfaces. In addition, as discussed in more detail below, both rear bushing <NUM> and front bushing <NUM> include a spring or biasing structure that exert outwardly directed forces causing a high level of engagement and tight fit between body <NUM> and the slidable body member <NUM>.

Rear bushing <NUM> is coupled to slidable body member <NUM> via fasteners <NUM> (e.g., screws) near enclosed end <NUM> of slidable body member <NUM>. During the extension or retraction of slidable body member <NUM> along frame <NUM>, spring <NUM> of rear bushing <NUM> slides along rear surface <NUM> of frame <NUM>. Front bushing <NUM> is coupled to frame <NUM> via fasteners <NUM> (e.g., screws) near open end <NUM>. During the extension or retraction of slidable body member <NUM> along frame <NUM>, springs <NUM> of front bushing <NUM> slide along recessed internal vertical surface <NUM> of slidable body member <NUM>. When slidable body member <NUM> is fully extended, stop surface <NUM> of rear bushing <NUM> engages with hard stop component <NUM> (best shown in <FIG>) to prevent further extension of slidable body member <NUM> and thus defines the maximum extendable length of the level.

Turning to <FIG>, rear bushing <NUM> is biased against and pushes level frame <NUM> by virtue of spring <NUM>. In particular spring <NUM> pushes against rear surface <NUM> of frame <NUM> in direction D1, which results in flexing of end <NUM> of spring <NUM> deforming in direction D2. The force exerted by spring <NUM> results in rear bushing <NUM> being biased in direction D2 away from frame <NUM>. As a result of that lateral force, rear bushing <NUM> maintains contact with frame <NUM> at internal angled surface <NUM> and slidable body member <NUM>. Rear bushing <NUM> includes a lower cavity <NUM> and an opposing upper cavity <NUM>.

Slidable body member <NUM> and frame <NUM> are coupled together via a dovetail fit, which allows slidable body member <NUM> and frame <NUM> to slide with respect to each other along longitudinal axis <NUM>. Upper longitudinal protrusion <NUM> of frame <NUM> is engaged within upper channel <NUM> of slidable body member <NUM>, and lower longitudinal protrusion <NUM> of frame <NUM> is engaged within lower channel <NUM> of slidable body member <NUM>. As a result, slidable body member <NUM> slides along longitudinal axis <NUM> by virtue of upper and lower longitudinal protrusions <NUM> and <NUM> of frame <NUM> engaging within upper and lower channels <NUM> and <NUM> of slidable body member <NUM> via a dovetail fit.

In general, level <NUM> comprises a frame <NUM> that comprises a base surface <NUM> and an opposing top surface <NUM>. Slidable body member <NUM> of level <NUM> comprises extension bottom surface <NUM> and upper edge <NUM>. Extension bottom surface <NUM> and frame bottom surface <NUM> are coplanar and collectively comprise base surface <NUM>. Base surface <NUM> and top surface <NUM> are flat, planar surfaces that can be used to engage a surface of a workpiece to be measured using level <NUM>. In some specific embodiments, base surface <NUM> and/or top surface <NUM> are machined to have a flat, flush or planar surface following formation of frame <NUM> (e.g., following extrusion of a metal forming frame <NUM>), and in some embodiments, this machined surface may be anodized. Surfaces <NUM> and <NUM> may be referred to as working surfaces of level <NUM>. Surfaces <NUM> and <NUM> are planar surfaces that are parallel to each other and are also parallel to a longitudinal axis <NUM> of level <NUM>. In various embodiments, upper edge <NUM> of slidable body member <NUM> is embedded in the plane of top surface <NUM>. In various other embodiments, upper edge <NUM> is slightly elevated above the plane of top surface <NUM>.

Turning to <FIG>, front bushing <NUM> is similarly biased against and pushes level frame <NUM> by virtue of springs <NUM>. In particular springs <NUM> push recessed internal vertical surface <NUM> in direction D2, which results in flexing ends <NUM> of springs <NUM> deforming in direction D1. The force exerted by springs <NUM> via interfacing portions <NUM> results in front bushing <NUM> being biased in direction D1 away from slidable body member <NUM>. Therefore, front bushing <NUM> maintains contact with frame <NUM> at internal angled surface <NUM>. Front bushing <NUM> includes a bottom cavity <NUM> and an opposing top cavity <NUM>, top cavity <NUM> being proximate upper end <NUM> of front bushing <NUM>.

Turning to <FIG>, braking mechanism <NUM> provides the user the ability to control the ease with which slidable body member <NUM> extends and retracts along level frame <NUM>. In general, springs <NUM> and <NUM> are positioned to provide a constant but relatively low level of friction to control the sliding of slidable body member <NUM> relative to frame <NUM>. When providing a low but non-zero level of friction, springs <NUM> and <NUM> increase the amount of force that must be applied in order to slide slidable body member <NUM> along frame <NUM>. This constant friction decreases the chance of unintended movement of slidable body member <NUM>. In specific embodiments, an adjustment control <NUM> (e.g., via a screw <NUM> or other mechanism) allows the user to adjust the amount of friction applied by braking mechanism <NUM> to slidable body member <NUM>, which in turn allows the user to adjust how freely slidable body member <NUM> slides relative to frame <NUM>.

Braking mechanism <NUM> may be adjusted to exert a biasing pressure against slidable body member <NUM> in direction D2. The increase in this frictional force between braking mechanism <NUM> and slidable body member <NUM> can be increased until the force required to move slidable body member <NUM> along longitudinal axis <NUM> is very large (and thus slidable body member <NUM> is effectively locked in position relative to frame <NUM>).

Adjustable interface <NUM> comprises protrusions <NUM> that engage with thread <NUM> of brake <NUM>. In various embodiments adjustable interface <NUM> is a custom-threaded bolt that matches the threads of nut <NUM>. As adjustable interface <NUM> is rotated, protrusions <NUM> correspondingly rotate within helical thread <NUM>, which causes brake <NUM> to move along lateral axis <NUM>. In one embodiment, when adjustable interface <NUM> is rotated in a clockwise direction, from the perspective of <FIG>, the engagement between protrusions <NUM> and thread <NUM> causes brake <NUM> to move in direction D2 towards front bushing <NUM>. As a result, engagement surface <NUM> of brake <NUM> moves towards front bushing <NUM>, and thereby increases the compressive force exerted between springs <NUM> and slidable body member <NUM>. When adjustable interface <NUM> is rotated in a counter-clockwise direction, from the perspective of <FIG>, the engagement between protrusions <NUM> and thread <NUM> causes brake <NUM> to move in direction D1 away from front bushing <NUM>. As a result, the compressive force exerted between springs <NUM> and slidable body member <NUM> is reduced, and less force is required to move slidable body member <NUM> along longitudinal axis <NUM>.

Turning to <FIG>, level <NUM> comprises one or more orientation measuring components <NUM>, for example vials <NUM>. As will be explained below, orientation measuring component <NUM> provides a visual backdrop for vials <NUM> that allows vials <NUM> to be more easily read and interpreted. Bracket <NUM> is secured within chamber <NUM> in level frame <NUM>. Mount <NUM> is placed within bracket <NUM> and secured via fasteners <NUM>. Vial frame <NUM> is placed in mount <NUM>, and vial <NUM> is mounted within vial frame <NUM>. In one embodiment, back surface <NUM>, sidewall surface <NUM> and bottom surface <NUM> of vial frame <NUM> are a contrasting color to a liquid within vial <NUM>. For example, in <FIG> surfaces <NUM>, <NUM> and <NUM> are relatively light (e.g., light grey, white, off-white) while the liquid in vial <NUM> is blue. In this example, the bubble within vial <NUM> is clearly visible compared to the blue liquid against the backdrop of surfaces <NUM>, <NUM> and <NUM>.

As noted above, when slidable body member <NUM> is fully extended, stop surface <NUM> of rear bushing <NUM> engages with hard stop component <NUM> to prevent further extension of slidable body member <NUM> and thus defines the maximum extendable length of the level. In various embodiments hard stop component <NUM> is mounted to one of frame <NUM> and slidable body member <NUM>.

Turning to <FIG>, when end cap <NUM> is removably coupled to fixed end <NUM> of frame <NUM>, internal member <NUM> of end cap <NUM> is slid within frame <NUM>. Engagement protrusion <NUM> presses against an internal surface of frame <NUM> and deforms engagement pivot <NUM> as pivot end <NUM> is partially rotated around pivot base <NUM>. When engagement protrusions <NUM> aligns with opening <NUM>, engagement protrusion <NUM> engages with opening <NUM>, thereby coupling end cap <NUM> and frame <NUM>. To remove, engagement protrusion <NUM> nearest pivot end <NUM> is pressed to de-couple engagement protrusion <NUM> from opening <NUM>.

Turning to <FIG>, to facilitate the extension of slidable body member <NUM>, extension end cap <NUM> includes a cavity, such as recess <NUM> behind back surface <NUM> of extension end cap <NUM>. A user may find gripping purchase with recess <NUM>, thus providing enough frictional engagement between the user and extension end cap <NUM> to allow slidable body member <NUM> to be axially moved with respect to frame <NUM>.

Turning to <FIG>, vial frame <NUM> is placed within bracket <NUM> and then mount <NUM> is attached. Bracket <NUM> is secured within chamber <NUM> of level frame <NUM>. Subsequent to bracket <NUM> being secured within chamber <NUM> of frame <NUM>, end cap <NUM> is inserted into frame <NUM>. As before, in various embodiments sidewall surface <NUM> are a contrasting color to (e.g., light grey, white, off-white) a liquid within vial <NUM>, which is blue. In this example, the bubble within vial <NUM> is clearly visible compared to the blue liquid against sidewall surface <NUM>.

In specific embodiments, the level body components (such as frame <NUM> and slidable body member <NUM>) discussed herein are each formed from a hollow piece of material, such as hollow pieces of metal material (e.g., hollow pieces of extruded aluminum). Further, it should be understood that the terms vertical and horizontal used herein refer to reference axes where horizontal is a plane that lies parallel to the working surfaces of the level and vertical is a plane that lies perpendicular to the working surfaces of the level.

In specific embodiments, one or more components of level <NUM>, such as bushings <NUM> and <NUM> and braking mechanism <NUM>, are formed from a low wear, relatively low friction and/or durable polymer material, such a polyoxymethylene polymer material, like Delrin available from DuPont. Further to facilitate fine adjustments of the amount of friction applied by braking mechanism <NUM>, brake <NUM> may have low pitch threading such that each rotation of screw <NUM> translates to a small adjustment in the vertical position change of brake <NUM>.

The expanding levels discussed herein comprises one or more bushing structures located between frame <NUM> and slidable body member <NUM>. In such embodiments, the bushing structures may provide for improved sliding via controlled friction and/or wear resistance as compared to an arrangement in which frame <NUM> directly engages slidable body member <NUM>.

In various embodiments, front bushing <NUM> and rear bushing <NUM> comprise a low friction, low wear polymer material providing bushing functionality between frame <NUM> and slidable body member <NUM>, facilitating sliding of slidable body member <NUM> relative to frame <NUM>.

Referring to <FIG>, level <NUM> is shown according to an exemplary embodiment. Level <NUM> is substantially the same as level <NUM>, except as disclosed and illustrated herein. Level <NUM> comprises rear bushing <NUM> and front bushing <NUM><NUM>, which are illustrated in <FIG> and <FIG>, respectively. Rear bushing <NUM> and front bushing <NUM> are substantially the same as rear bushing <NUM> and front bushing <NUM>, respectively, except as disclosed and illustrated herein.

Referring to <FIG>, rear bushing <NUM> is shown according to an exemplary embodiment. Rear bushing <NUM> is substantially the same as rear bushing <NUM>, except as disclosed and illustrated herein. Rear bushing <NUM> comprises engagement component <NUM> having ribs <NUM>. Rear bushing <NUM> is coupled to slidable body member <NUM>. During extension or retraction of slidable body member <NUM> along frame <NUM>, engagement component <NUM> generally, and ribs <NUM> specifically, engage against frame <NUM>. In various embodiments engagement component <NUM> generally and ribs <NUM> specifically are configured to provide a reduced and/or minimized resistance when sliding against frame <NUM>. In various embodiments, spring <NUM> in rear bushing <NUM> extends further than upper protrusion <NUM> and lower protrusion <NUM> (best shown in <FIG>).

Referring to <FIG>, front bushing <NUM> is shown according to an exemplary embodiment. Front bushing <NUM> is substantially the same as front bushing <NUM>, except as disclosed and illustrated herein. Front bushing <NUM> comprises engagement component <NUM>.

Front bushing <NUM> is coupled to frame <NUM>. During extension or retraction of slidable body <NUM> along frame <NUM>, engagement component <NUM> engages against slidable body member <NUM>. Springs <NUM> in front bushing <NUM> extend laterally and/or upwards towards slidable body member <NUM>, whereas springs <NUM> in front bushing <NUM> are arcuate shaped (best shown in <FIG> and <FIG>), and initially extend towards slidable body member <NUM> and later extend away from slidable body member <NUM>. In various embodiments engagement component <NUM> generally is configured to provide a reduced and/or minimized resistance when sliding against slidable body member <NUM>.

Referring to <FIG>, braking mechanism <NUM> is shown according to an exemplary embodiment. Braking mechanism <NUM> is substantially the same as braking mechanism <NUM>, except as disclosed and illustrated herein. Tightener bracket <NUM> includes apertures <NUM> on the surface facing away from brake <NUM>. In various embodiments of braking mechanism <NUM>, thread <NUM> in brake <NUM> is molded within brake <NUM>.

Referring to <FIG>, level <NUM> is shown according to an exemplary embodiment. Level <NUM> is substantially the same as level <NUM>, except as disclosed and illustrated herein. Level <NUM> comprises front bushing <NUM> and braking mechanism <NUM>. In the embodiment shown, springs <NUM> of front bushing <NUM> extend towards end cap <NUM>.

Referring to <FIG>, level <NUM> is shown according to an exemplary embodiment. Level <NUM> is substantially the same as level <NUM>, except as disclosed and illustrated herein.

It should be understood that the figures illustrate the exemplary embodiments in detail, and it should be understood that the present application is not limited to the details or methodology set forth in the description or illustrated in the figures.

Further modifications and alternative embodiments of various aspects of the invention will be apparent to those skilled in the art in view of this description. Accordingly, this description is to be constmed as illustrative only. The construction and arrangements, shown in the various exemplary embodiments, are illustrative only. Although only a few embodiments have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter described herein. Some elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. The order or sequence of any process, logical algorithm, or method steps may be varied or re-sequenced according to alternative embodiments.

Unless otherwise expressly stated, it is in no way intended that any method set forth herein be construed as requiring that its steps be performed in a specific order. Accordingly, where a method claim does not actually recite an order to be followed by its steps or it is not otherwise specifically stated in the claims or descriptions that the steps are to be limited to a specific order, it is in no way intended that any particular order be inferred. In addition, as used herein the article "a" is intended to include one or more components or elements, and is not intended to be construed as meaning only one.

Various embodiments of the invention relate to any combination of any of the features, and any such combination of features may be claimed in this or future applications. Any of the features, elements, or components of any of the exemplary embodiments discussed above may be utilized alone or in combination with any of the features, elements, or components of any of the other embodiments discussed above.

Claim 1:
A level (<NUM>) comprising:
a frame (<NUM>) comprising:
a first planar base surface (<NUM>);
a top surface (<NUM>) opposing the base surface (<NUM>);
a longitudinal axis (<NUM>);
a fixed end (<NUM>) at a first end of the longitudinal axis (<NUM>);
an open end (<NUM>) opposing the fixed end; and
an orientation measuring component (<NUM>);
a slidable body member (<NUM>) coupled to the frame (<NUM>) that extends and retracts along the longitudinal axis (<NUM>) of the frame (<NUM>), the slidable body member (<NUM>) comprising:
a second planar base surface (<NUM>) generally coplanar with the first planar base surface (<NUM>);
an enclosed end (<NUM>); and
an adjustable end (<NUM>) opposing the enclosed end (<NUM>), the adjustable end (<NUM>) extending past the open end (<NUM>) of the frame (<NUM>) when the slidable body member (<NUM>) is fully extended;
characterized in:
a first bushing (<NUM>) that couples the slidable body member (<NUM>) and the frame (<NUM>), the first bushing (<NUM>) fixedly coupled to one of the frame (<NUM>) or the slidable body member (<NUM>); and
a second bushing (<NUM>) that couples the slidable body member (<NUM>) and the frame (<NUM>), the second bushing (<NUM>) fixedly coupled to one of the frame (<NUM>) or the slidable body member (<NUM>).