Patent Description:
According to the invention there is provided a level includes a level body defining a reference surface configured to engage a workpiece. The level includes a vial supported by the level body and including an inner surface defining a cavity. The level includes a solid indicator located within the cavity. The solid indicator includes a first surface located at a first end of the solid indicator and a second surface located at a second end of the solid indicator opposite the first surface. The solid indicator moves within the vial in response to changing angular positions of the level body, and the solid indictor is shaped such that the first surface and the second surface are oriented in a direction perpendicular to the reference surface when the reference surface is oriented in a horizontal direction. The solid indicator includes at least one rolling element that supports the solid indicator and that engages the inner surface of the vial such that the solid indicator translates relative to the vial via rolling of the rolling element along the inner surface of the vial.

<FIG> illustrate various vials having various constructions to increase visibility, accuracy and readability. <FIG> illustrates a level <NUM> including a level body <NUM> supporting a first vial, shown as level vial <NUM>, and a second vial, shown as plumb vial <NUM>. The vials of <FIG> may be configured with the level <NUM> in place of the level vial <NUM>, the plumb vial <NUM>, or both. The vials of <FIG> may be configured with the level <NUM> and corresponding base surface(s), shown as reference surfaces <NUM>, of the level <NUM>, such that the vials are oriented to determine if a surface is plumb (i.e., vertical), level (i.e., horizontal), or oriented at any other desired reference angle. The vials of <FIG> may be formed from glass, a clear polymer (e.g., acrylic), or another suitable material. Alternatively, the vials may be configured with any other suitable tool, device, or structure.

<FIG> illustrates a vial <NUM> including an inner surface <NUM> that defines an interior cavity <NUM> that holds a first material, shown as first fluid <NUM> (e.g., alcohol, mineral spirit, etc.), and a second material, shown as a second fluid <NUM> (e.g., gas, air, liquid, etc.). The second fluid <NUM> is suspended in the first fluid <NUM> forming an indicator, shown as globule or bubble <NUM>, to act as an inclination indicator. Where second fluid <NUM> is a gas or air, bubble <NUM> is a bubble containing the gas or air of second fluid <NUM> separated from first fluid <NUM>. The second fluid <NUM> may be a liquid material, and the first fluid <NUM> and the second fluid <NUM> immiscible relative to each other such that bubble <NUM> is a bubble containing the liquid of second fluid <NUM> separated from first fluid <NUM>.

As shown in <FIG>, the separation of first fluid <NUM> from second fluid <NUM> defines an interface <NUM> between the two different materials of fluids <NUM> and <NUM>. In <FIG>, to enhance visibility of bubble <NUM>, vial <NUM> includes a third material <NUM> that has a property that attracts third material <NUM> to interface <NUM>. As will be explained in more detail below, the property of third material <NUM> is one that differentially attracts third material <NUM> to interface <NUM> such that third material <NUM> tends to be located at interface <NUM> (or returns to interface <NUM> following disruption) rather than being dispersed within fluids <NUM> and <NUM>.

The third material <NUM> is attracted to an exterior surface of the second fluid <NUM>. The third material <NUM> is another fluid immiscible with the first and second fluids <NUM>, <NUM>. The third material <NUM> may be a particulate material or any other suitable material that is attracted to the interface <NUM> (e.g., attracted to the second fluid <NUM> and not the first fluid <NUM>, or alternatively repelled by the first fluid <NUM>). The third material <NUM> may partially or entirely surround the bubble <NUM>, and may have various thicknesses. As will be explained in more detail below, Applicant believes that use of third material <NUM> within vial <NUM> tends to enhance the visibility of interface <NUM> such that the location and position of bubble <NUM> is easier for a user to see when using a level incorporating vial <NUM>.

The differential property of the third material <NUM> that attracts it to interface <NUM> may be density, wherein the density of the third material <NUM> is less than the density of fluid <NUM> but is greater than the density of fluid <NUM>. In this, the third material <NUM> tends to reach positional equilibrium at interface <NUM> between fluids <NUM> and <NUM>. The fluid <NUM> may be an air or gas, and third material <NUM> floats on fluid <NUM> at interface <NUM>.

The differential property of the third material <NUM> that attracts it to interface <NUM> may be polarity, wherein the polarity of third material <NUM> is different from the polarity of fluids <NUM> and <NUM>. The fluid <NUM> may be a polar fluid, and fluid <NUM> is a nonpolar fluid. The fluid <NUM> may be a nonpolar fluid, and fluid <NUM> is a polar fluid.

The third material <NUM> may be an amphipathic material (e.g., a material having a polar region and a nonpolar region). The fluid <NUM> may be a polar fluid, and fluid <NUM> is a nonpolar fluid. The fluid <NUM> may be a nonpolar fluid, and fluid <NUM> is a polar fluid. The third material <NUM> may form a layer or membrane with polar and nonpolar regions of the amphipathic material oriented based on the attraction of those regions to the polarity of fluids <NUM> and <NUM>.

The third material <NUM> may accentuate the peripheral boundaries of the bubble <NUM> to provide improved visibility of the bubble <NUM> within the vial <NUM>, and improved readability of the position of the bubble <NUM> relative to a pair of indicator lines <NUM> of the vial <NUM>. The first fluid <NUM>, the second fluid <NUM>, and the third material <NUM> may be oil, water, and dish soap, respectively. When the third material <NUM> becomes separated from the surface of the bubble <NUM> (e.g., by dropping the level, shaking, agitation, etc.), the third material <NUM> may be configured to return to the surface of the bubble <NUM> in less than about <NUM> seconds, in less than about <NUM> seconds, in less than about <NUM> second, or in less than about <NUM> seconds. When the third material <NUM> becomes separated from interface <NUM> via a drop to the ground from a horizontal position four feet (i.e. approximately <NUM>) above the ground, the third material <NUM> (e.g., at least <NUM>% of third material <NUM>) may return back to interface <NUM> in less than <NUM> seconds, specifically in less than <NUM> seconds, more specifically, in less than <NUM> second, and even more specifically in less than <NUM> seconds.

The third material <NUM> may have a property that is different than a property of fluids <NUM> and <NUM> which accentuates, highlights or otherwise improves visibility of interface <NUM>. The third material <NUM> may have an optical property that is different than the same optical property of fluid <NUM> and/or of fluid <NUM>. The third material <NUM> may have a light transmittance, a light emittance, or index of refraction, that is different from the light transmittance, light emittance, or index of refraction, respectively, of fluid <NUM> and/or of fluid <NUM>. The third material <NUM> may have a light transmittance at a wavelength of between <NUM> to <NUM> that is greater than a light transmittance at the wavelength of the first fluid <NUM> and/or of second fluid <NUM>.

The vial <NUM> may include first fluid <NUM> that is a first liquid and second fluid <NUM> that is a second liquid. The vial <NUM> may not include third material <NUM>, and visibility is enhanced simply by the nature of interface <NUM> formed between the two liquid materials of fluids <NUM> and <NUM>. The bubble <NUM> may be a bubble of the liquid material of fluid <NUM> that separates from the liquid of fluid <NUM>. The liquid of second fluid <NUM> may be less dense that fluid <NUM>, may be more polar than fluid <NUM>, less polar than fluid <NUM> and/or may be an amphipathic material. The fluid <NUM> may be an amphipathic material that arranges itself into a micelle arrangement within fluid <NUM>.

<FIG> illustrate a flat vial <NUM> including a transparent elongated block <NUM>. The block <NUM> has a bottom side <NUM>, a top side <NUM> and a pair of vertical sides <NUM>. The block <NUM> defines a T-shaped interior cavity <NUM>, as shown in <FIG>. In addition, the cavity <NUM> is filled with a first fluid <NUM> and an air bubble <NUM>, or immiscible second fluid, to act as an inclination indicator. The T-shaped interior cavity <NUM> has a first, vertical portion <NUM> parallel with the vertical sides <NUM>, and a second, horizontal portion <NUM> parallel with the top side <NUM>. With reference to <FIG>, the second portion <NUM> has a width W2 that is significantly wider than a width W1 of the first portion <NUM>. In addition, with reference to <FIG>, the second portion <NUM> has a height H2 significantly less than a height H1 of the first portion <NUM> (e.g., the height H2 of the second portion <NUM> may be less than <NUM>/16th of an inch, i.e., less than approximately <NUM>). Thus, the visibility of the second portion <NUM> is minimized when viewing the bubble <NUM> from either of the vertical sides <NUM>. The third material <NUM> of the vial <NUM> of <FIG> may be used to provide further visibility of the bubble <NUM>, as described above with respect to vial <NUM> of <FIG>. The first portion <NUM> and the second portion <NUM> both have a concave or barrel shape so that the bubble <NUM> settles toward the center of the second portion <NUM> when the flat vial <NUM> is horizontal.

In use, the vial <NUM> of <FIG> provides enhanced visibility by forcing the bubble <NUM> to appear larger in the views where it typically appears small. For example, from either of the vertical sides <NUM> (<FIG>) the bubble <NUM> is seen extending horizontally across the first portion <NUM> of the cavity <NUM> providing for increased visibility of the bubble <NUM>. When viewing the vial <NUM> from the top side <NUM> (<FIG>) a portion of the bubble may be located in the second portion <NUM> such that the bubble <NUM> may be seen extending across the second portion <NUM> of the cavity <NUM>, which may provide for increased visibility of the bubble <NUM> based on the greater dimension of the width W2 of the second portion <NUM> compared to that of the width W1 of the first portion <NUM> (i.e., compared to a flat vial without a second portion <NUM>). Thus, the second portion <NUM> provides improved visibility of the bubble <NUM> and readability of the position of the bubble <NUM> relative to a pair of indicator lines <NUM>, when viewing the bubble <NUM> from the top side <NUM>, as shown in <FIG>. Without the second portion <NUM> the bubble <NUM> would be as thin as the width W1 of the first portion <NUM>. Thus, the bubble <NUM> would be difficult to see and read when viewing from the top side <NUM>.

<FIG> illustrate an annular vial <NUM> including a disc-shaped body <NUM>. The body <NUM> defines an annular interior cavity <NUM> with a varying cross-sectional area. The interior cavity <NUM> contains a first fluid <NUM> and air <NUM>, or alternatively a second fluid being immiscible with the first fluid <NUM>. The interior cavity <NUM> has a first portion <NUM> and a second portion <NUM> opposite the first portion <NUM>. The first portion <NUM> has a first width A1 defining a first cross-sectional area and the second portion <NUM> has a second width A2 defining a second cross-sectional area. The first width A1 is wider than the second width A2. Due to the depth (i.e., dimension perpendicular to <FIG>) of the cavity <NUM> being uniform and to the first cross-sectional area being greater than the second cross-sectional area, the first portion <NUM> has a larger volume than the second portion <NUM>.

Due to the difference in volume between the first portion <NUM> and the second portion <NUM>, tilting the annular vial <NUM> from a first position, shown in <FIG>, to a second position, shown in <FIG>, displaces the fluid <NUM> from the first portion <NUM> to the second portion <NUM> causing a small change in the amount of fluid <NUM> that occupies the first portion <NUM> (as a function of the total amount of fluid in the first portion <NUM>) while causing a large change in the amount of fluid <NUM> that occupies the second portion <NUM> (as a function of the total amount of fluid in the second portion <NUM>), as shown in <FIG>. In other words, a small change in the height or fluid level (i.e., area where the first fluid <NUM> and the air <NUM> are in contact) of the fluid <NUM> in the first portion <NUM> causes a large change in height of the fluid <NUM> in the second portion <NUM>. Thus, small angular changes of the annular vial <NUM> have increased perceptibility and readability due to the large change in the height of the fluid in the second portion <NUM> of the cavity <NUM>. As such, a surface can be more accurately measured for level or plumb using the annular vial <NUM>. The depth (i.e., dimension perpendicular to <FIG>) of the cavity may be larger in the first portion <NUM> than in the second portion <NUM> to provide an even larger difference in volume between the first portion <NUM> and the second portion <NUM> and cause a larger change in height of the fluid <NUM> in the second portion <NUM>.

The annular vial <NUM> may include indicator marks <NUM> positioned circumferentially around the annular vial <NUM> that are calibrated with the amount of the fluid <NUM> within the cavity <NUM> to indicate when the vial <NUM> is level (i.e., horizontal). Alternatively, the indicator marks <NUM> may be located around the vial <NUM> on vial surrounds or a level supporting the vial <NUM>. Additionally, because of the continuous annular cavity <NUM> the annular vial <NUM> may be used as both a level vial and a plumb vial to determine horizontal or vertical without the need to reorient the vial or use a separate vial.

<FIG> illustrate a vial <NUM> including a body <NUM> defining an interior cavity <NUM>. The interior cavity <NUM> has a first portion <NUM> that contains a first fluid <NUM> and a second portion <NUM> that contains air <NUM>, or alternatively an immiscible second fluid, when the vial <NUM> is horizontal, as shown in <FIG>. The first fluid <NUM> defines a fluid level <NUM>. The vial <NUM> further includes a reference line <NUM> to indicate that the vial <NUM> is horizontal when the fluid level <NUM> is aligned or parallel with the reference line <NUM>, as shown in <FIG>. The vial further includes a plurality of spaced obstructions <NUM> that define a plurality of narrow channels <NUM> between the obstructions <NUM>. The narrow channels <NUM> fluidly connect the first portion <NUM> and the second portion <NUM> of the cavity <NUM>. The obstructions <NUM> reduce the cross-sectional area, and thus volume, between the first portion <NUM> and the second portion <NUM> to that of the narrow channels <NUM>. Thus, as the vial <NUM> is tilted the first fluid <NUM> moves upwardly through the narrow channels <NUM> such that a height H3 between the fluid level <NUM> and the reference line <NUM> is increased, as shown in <FIG>. Due to the narrow channels <NUM> the visibility of the fluid level <NUM> and readability of the vial <NUM> is increased. As such, a user can more readily and accurately determine if the fluid level <NUM> is aligned with the reference line <NUM>, and therefore more accurately determine if a measured surface is level or plumb.

<FIG> illustrate a vial <NUM> for a level tool <NUM> of <FIG> according to the invention. The vial <NUM> includes a transparent/translucent cylindrical body <NUM> having a cavity or an inner bore <NUM> defined by an inner surface <NUM> and includes a solid indicator <NUM> located within bore <NUM>. In this embodiment, solid indicator <NUM> replaces the air bubble common to standard spirit level tools and is configured to move within bore <NUM> based on the angular position or inclination of level <NUM>.

To provide inclination indication, solid indicator includes a first surface <NUM> located at a first end of solid indicator <NUM> and a second surface <NUM> located at a second end of solid indicator <NUM> that is opposite of first surface <NUM>. As shown in <FIG>, when the level body or the reference surface (see reference surface <NUM> in <FIG>) is oriented in the horizontal direction, surfaces <NUM> and <NUM> are orientated in a direction perpendicular to the reference surface (i.e., vertically when reference surface is horizontal). In some embodiments, surfaces <NUM> and <NUM> are mirror images of each other, and in the particular embodiment shown, surfaces <NUM> and <NUM> are planar surfaces that are substantially parallel to each other (e.g., at an angle of less than <NUM> degrees relative to each other, specifically less than <NUM> degree relative to each other, etc.). In other embodiments, surfaces <NUM> and <NUM> may be non-planar surfaces (e.g., curved surfaces) and in such embodiments, the orientation of surfaces <NUM> and <NUM> relative to the reference surface <NUM> of level <NUM> noted above relates to orientation of a major or minor axis of the curved surfaces <NUM> and <NUM>.

In general, visibility of inclination/level indication provided by vial <NUM> is enhanced by use of indicator <NUM> because Applicant believes that the visibility of surfaces <NUM> and <NUM> relative to indicator lines <NUM> and <NUM> is enhanced (at least as compared to some typical bubble/spirit vial designs). As shown in <FIG>, indicator lines <NUM> and <NUM> are substantially parallel lines, and when vial <NUM> is indicating a high degree of levelness, indicator <NUM> is generally located between lines <NUM> and <NUM> such that surfaces <NUM> and <NUM> are positioned adjacent to or aligned with lines <NUM> and <NUM>, respectively. This allows the user see that levelness is indicated by vial <NUM> by viewing the position of surfaces <NUM> and <NUM> relative to the position of indicator lines <NUM> and <NUM>.

In specific embodiments, a length, L1, is defined between lines <NUM> and <NUM>, and indicator <NUM> has a length, L2, defined between surfaces <NUM> and <NUM>. As can be seen by <FIG>, the alignment between surfaces <NUM> and <NUM> and lines <NUM> and <NUM> in the level position are based on the relative size of L2 to L <NUM>. In specific embodiments, L2 is between <NUM>% and <NUM>% of L1, specifically between <NUM>% and <NUM>% of L1 and more specifically between <NUM>% and <NUM>% of L1. In a specific embodiment, the horizontal distance between surfaces <NUM> and <NUM> and lines <NUM> and <NUM>, respectively when in the horizontal position, is less than <NUM>.

In various embodiments, vial <NUM> is configured to contain a liquid, gas or vacuum within bore <NUM> surrounding indicator <NUM>. In one embodiment, vial <NUM> is configured to hold a fluid (e.g., alcohol, mineral spirits, etc.), and solid "bubble" or indicator <NUM> suspended in the fluid. The solid indicator <NUM> includes a rolling element, shown as sphere <NUM> and a cuboid <NUM>. In this embodiment, the cuboid <NUM> defines the pair of opposite end faces <NUM>, <NUM> and four longitudinal faces <NUM> extending between the end faces <NUM>, <NUM>. Each of the longitudinal faces <NUM> defines a circular window <NUM>. The sphere <NUM> is formed from a dense material (e.g., metal, hard plastic, etc.) and is preferably solid, with some embodiments employing a hollow sphere if desired.

As shown in <FIG>, the sphere <NUM> is positioned within the cuboid <NUM> such that the sphere <NUM> protrudes partially out of the circular windows <NUM>. The sphere <NUM> rotates freely within the cuboid <NUM> such that the sphere <NUM> can roll along an inner surface of the bore <NUM>, thereby allowing the indicator <NUM> to move axially within the cylindrical body <NUM> of the vial <NUM>. As the vial <NUM> is tilted with respect to the axis being measured the indicator <NUM> moves toward the lower end of the vial <NUM>. The inner surface of the bore <NUM> has a concave or barrel shape that allows for the indicator <NUM> to settle toward the center of the bore <NUM> when the vial <NUM> is parallel to the axis being measured. In use, similar to levels that use air bubbles, a surface is indicated as level or plumb, when the indicator <NUM> falls between a pair of indicator marks or lines on the body <NUM>. The end faces <NUM> are parallel with the indicator lines on the cylindrical body <NUM> of the vial <NUM>. Thus, the distance between the end faces <NUM> and the corresponding indicator line may be easily determined, increasing readability in comparison to a sphere <NUM> or bubble. In addition, the color of the cuboid <NUM> and the material used to manufacture the cuboid <NUM> can be selected to assure that the cuboid <NUM> stands out and is easily visible in common or desired lighting circumstances. Therefore, the cuboid <NUM> provides increased visibility and accuracy to the indicator <NUM> within the vial <NUM>.

<FIG> illustrate a spirit level <NUM> including a frame body <NUM>, an interior support structure or cartridge <NUM>, and a center vial assembly <NUM> having a center vial <NUM>. The frame body <NUM> is a box level-type frame having a top planar wall <NUM>, a bottom planar wall <NUM> and a pair of parallel sidewalls <NUM> (only one is shown) connecting the top planar wall <NUM> and the bottom planar wall <NUM> to define an internal cavity running along a length of the level <NUM>. A generally U-shaped frame cutout <NUM> is defined by the sidewalls <NUM> and the top planar wall <NUM>. The level <NUM> may be an I-beam level, a torpedo level, or any other type of level or device utilizing a spirit vial.

With reference to <FIG>, the interior support structure <NUM> defines an interior support cutout <NUM>. The interior support structure <NUM> has a plurality of flanges <NUM> that extend perpendicularly from a central web <NUM>. The interior support structure <NUM> slides within the cavity through an open end (not shown) of the frame body <NUM> such that the central web <NUM> is parallel to the sidewalls <NUM> and is positioned such that the interior support cutout <NUM> aligns with the frame cutout <NUM> in the frame body <NUM>. The flanges <NUM> include a top flange <NUM> adjacent the top planar wall <NUM> of the frame body <NUM>, and a bottom flange <NUM> adjacent the bottom planar wall <NUM> of the frame body <NUM>. The interior support structure <NUM> provides structural support and increased stiffness to the frame body <NUM> of the level <NUM> around the frame cutout <NUM> in the frame body <NUM>. The interior support structure <NUM> is secured to the frame body <NUM> by adhesive (e.g., epoxy) injected through adhesive passageways <NUM> defined in the interior support structure <NUM>. In addition to or in lieu of adhesive, the interior support structure <NUM> may be secured to the frame body <NUM> via fasteners or other securing means.

With reference to <FIG> and <FIG>, the vial <NUM> includes a translucent vial body <NUM> having a cavity <NUM>. The vial body <NUM> has first and second ends <NUM>, <NUM> and a longitudinal axis A extending therebetween. The cavity <NUM> is barrel shaped such that the cavity <NUM> has a maximum diameter <NUM> defined at a center of the cavity <NUM> of the vial <NUM> along the longitudinal axis A. The cavity <NUM> contains an indicator bubble <NUM> formed of a first fluid and preferably a gas (e.g., air) and a second fluid preferably a liquid <NUM> (e.g., alcohol). The bubble <NUM> is suspended in the liquid <NUM> such that the bubble <NUM> is generally centered on the maximum diameter <NUM> when the vial is oriented parallel to true horizontal (i.e., perpendicular to gravity). The vial <NUM> includes circumscribed marker rings or indicator lines (similar to marker rings <NUM> of <FIG>) that are equidistant from and parallel to the maximum diameter <NUM> and positioned such that when the bubble <NUM> is between the marker rings the bubble <NUM> is generally centered on the maximum diameter <NUM>, and thus the vial <NUM> is parallel to true horizontal. An interface between the bubble <NUM> and the liquid <NUM> forms a meniscus <NUM> defining a discrete perimeter of the bubble <NUM>.

With reference to <FIG>, the vial assembly <NUM> further includes an outer vial surround <NUM> and an inner vial surround <NUM> for supporting the vial <NUM> on the frame body <NUM> of the level <NUM>. The inner vial surround <NUM> has a generally U-shaped body <NUM> having opposing end vial supports <NUM> that define vial support recesses <NUM> that hold and support the first and second ends <NUM>, <NUM> of the vial <NUM> (<FIG>). The body <NUM> defines a bottom opening <NUM> extending longitudinally between the opposing end vial supports <NUM>. In an alternate inner vial surround 696a, as shown in <FIG>, the vial support recesses 732a extend through the opposing end vial supports <NUM> such that the vial support recesses 732a define openings that are continuous with the bottom opening 728a. The end vial supports 724a of the body 720a are provided with resilient flexibility so that opposing halves <NUM> of the end vial supports 724a flex outwardly away from each other when the vial <NUM> is inserted through the bottom opening 728a. Once the vial <NUM> is fully inserted, such that first and second ends <NUM>, <NUM> are received by the vial support recesses 732a, the end vial supports 724a spring back to hold the vial <NUM> within the inner vial surround 696a. The inner vial surround 696a may be translucent.

With reference to <FIG> and <FIG>, the outer vial surround <NUM> includes a flat base <NUM>, and first and second outer support projections <NUM>, <NUM> extending from opposite ends of the flat base <NUM>. The base <NUM> includes an upper surface that faces vial <NUM> (see <FIG>), and this upper surface includes a middle portion <NUM> and a pair of outer portions <NUM> adjacent each side of the middle portion <NUM>. The middle portion <NUM> is a light color, such as white or another light color. The outer portions <NUM> are a dark color, such as black or another dark color.

The outer vial surround <NUM> may be made from a two-shot injection molding process so that the middle portion <NUM> is light colored and the outer portions <NUM> are dark colored. The outer vial surround <NUM> may be formed from a single colored material and the middle portion <NUM> and/or the outer portions <NUM> are coated or layered with their respective desired colors. The middle portion <NUM> and the outer portions <NUM> are made from different colored materials in order to obtain the respective light and dark colors of the middle portion <NUM> and outer portions <NUM> and then are coupled together to form the multicolored outer vial surround <NUM>. The middle portion <NUM> and the outer portions <NUM> generally divide the base <NUM> into thirds longitudinally along the base <NUM>.

With continued reference to <FIG>, the first outer support projection <NUM> of the outer vial surround <NUM> defines a vial receiving opening <NUM> that is sized to slidingly receive the inner vial surround <NUM> axially along the longitudinal axis A of the vial <NUM> and support the inner vial surround <NUM> and the vial <NUM> on the base <NUM> of the outer vial surround <NUM>. The bottom opening <NUM> of the inner vial surround <NUM> is aligned over the base <NUM> such that the middle portion <NUM> and the outer portions <NUM> of the base <NUM> can be viewed through the vial <NUM>. The middle portion <NUM> is centered on the bubble <NUM> and the outer portions <NUM> are adjacent the first and second ends <NUM>, <NUM> of the vial <NUM>. The level <NUM> may not include an inner vial surround <NUM>, instead the vial <NUM> is supported directly by the outer vial surround <NUM>.

With reference to <FIG> and <FIG>, the center vial surround assembly <NUM> is received within the frame cutout <NUM> and the interior support cutout <NUM> in the interior support structure <NUM>. The center vial surround assembly <NUM> is secured to interior support structure <NUM> and the frame body <NUM> using adhesive, such as epoxy. The center vial surround assembly <NUM> may be secured to the frame body <NUM> by fasteners or any other suitable manner of securing the center vial surround assembly <NUM> to the frame body <NUM>.

Presence of dark-colored outer portions <NUM> creates regions adjacent vial <NUM> with decreased light reflection (resulting in the darker color) as compared to central area <NUM>, to other parts of the level, to the surrounding environment, etc. Thus, in use, when viewing the vial <NUM>, the relatively low levels of light from the dark-colored outer portions <NUM> of the base <NUM> of the outer vial surround <NUM> reflects off and refracts through the meniscus <NUM> of the bubble <NUM> to darken at least a portion of the perimeter of the bubble <NUM>. In particular, opposing longitudinal end portions <NUM> of the bubble <NUM> are darkened by reflected light from the dark-colored outer portions <NUM> of the base <NUM> (similar to <FIG>). Thus, the alternating dark and light colored sections of the upper surface of outer vial surround <NUM> provide improved visibility of the position of the meniscus <NUM> of the bubble <NUM> within the vial <NUM>; and specifically, improved visibility of the end portions <NUM> of the bubble <NUM> relative to the corresponding adjacent marker rings.

In addition, the light-colored middle portion <NUM> of the base <NUM> provides a light-colored background for the darkened end portions <NUM> of the bubble <NUM> to contrast against, further improving visibility of the bubble <NUM>. In particular, the light-colored middle portion <NUM> provides improved contrast and visibility when the viewer views the vial <NUM> from a position directly above the level <NUM> so that the light-colored middle portion <NUM> of the base <NUM> is positioned beneath the bubble <NUM> such that the darkened end portions <NUM> contrasts with the light-colored middle portion <NUM> to improve visibility of the bubble <NUM>. In addition, corresponding interfaces where the light-colored middle portion <NUM> meets the dark-colored outer portions <NUM> may be aligned with the marker rings on the vial <NUM> so as to provide improved delineation and contrast to more easily determine if the bubble <NUM> is centered within the vial <NUM>. Accordingly, the viewer can more accurately determine if the bubble <NUM> is positioned centrally within the vial <NUM> between the marker rings (i.e., the vial is oriented parallel to true horizontal). The entire perimeter of the bubble <NUM> may be darkened for improved contrast and visibility.

In addition, central portion <NUM> may be sized such that the transitions between the light colored central portion <NUM> and the dark colored outer portions <NUM> are positioned near the ends of the indicating bubble <NUM>. As noted, this positioning provides for high contrast along ends <NUM> of bubble <NUM>. Specifically, as shown in <FIG>, bubble <NUM> has a length, L3, in a direction parallel to the longitudinal axis of the level body and of the reference surface that is between <NUM>% and <NUM>% of the length of central portion <NUM>, L4, in the same direction.

The different darkness levels of outer sections <NUM> and central section <NUM> is relatively large and can be expressed in terms of the Munsell color system. The lighter color of central section <NUM> may have a Munsell color value greater than the Munsell color value of the darker outer sections <NUM>. The lighter color of central section <NUM> may have a Munsell color value of greater than or equal to <NUM>, and the Munsell color value of the darker outer sections <NUM> may be less than <NUM>.

<FIG> illustrates another vial 616b that, with the exception of some minor distinctions, is substantially similar to the vial <NUM> of <FIG> and may be used in its place with the level <NUM>. Like components and features are identified with like reference numerals plus the letter "b" and will not be described again in detail. Only differences between the two vials will be described in detail.

The vial 616b includes circumscribed marker rings or indicator lines <NUM> that are equidistant from and parallel to the maximum diameter 672b and positioned such that when the bubble 676b is between the marker rings <NUM> the bubble 676b is generally centered on the maximum diameter 672b, and thus the vial <NUM> is parallel to true horizontal. The vial 616b further includes first and second dark-colored bands <NUM>, <NUM> circumscribing the cavity 660b of the vial 616b. The first dark-colored band <NUM> is positioned between the maximum diameter 672b and the first end 664b of the vial 616b. The second dark-colored band <NUM> is positioned between the maximum diameter 672b and the second end 668b of the vial 616b. The dark-colored bands <NUM>, <NUM> are black, but may be any dark color, and may be opaque or translucent. The portion of the vial body <NUM> between the first and second dark-colored bands <NUM>, <NUM> is unobstructed and translucent so as to clearly see the bubble 676b through the vial body <NUM>. When viewing the vial 616b, the dark-colored bands <NUM>, <NUM> function similarly to the dark-colored outer portions <NUM> of the base <NUM> to reflect light so as to reflect off or refract through the meniscus 684b of the bubble 676b to darken at least a portion of the perimeter of the bubble 676b, thereby further improving contrast between the meniscus 684b and the liquid 680b. In particular, the end portions 748b of the bubble 676b are darkened by reflected light from the dark-colored outer portions <NUM>. The vial 616b including the dark-colored bands <NUM>, <NUM> may be used alone or in conjunction with the dark-colored outer portions <NUM> of the base <NUM> of the outer vial surround <NUM>. Each of the dark-colored bands <NUM>, <NUM> are arranged to directly align above a corresponding one of the dark-colored outer portions <NUM> of the base <NUM> so as to further enhance the darkness of the darkened portion of the bubble 676b to provide improved contrast between the darkened portion of the bubble 676b, and the liquid <NUM> and/or the light-colored middle portion <NUM>.

<FIG> illustrates another level 600c that, with the exception of some minor distinctions, is substantially similar to the level <NUM> of <FIG>. Like components and features are identified with like reference numerals plus the letter "c" and will not be described again in detail. Only differences will be described in detail.

The interior support structure 608c further defines a bore <NUM> extending from the interior support cutout 634c toward the bottom planar wall 624c into a cavity <NUM> sized to receive a standoff member <NUM>. The bore <NUM> is threaded so as to receive a threaded fastener (not shown). In addition, the outer vial surround 692c includes projections <NUM> extending downward from the base 704c that are received within the adhesive passageways 652c.

During assembly of the level 600c, the threaded fastener is threaded into the bore <NUM> so as to apply a downward force F1 on the standoff member <NUM>, thereby urging the standoff member <NUM> into contact with the bottom planar wall 624c. Continuing to thread the threaded fastener through the bore <NUM> causes the standoff member <NUM> to apply a downward force F2 on the bottom planar wall 624c, thereby driving the interior support structure 608c upward into contact with the top planar wall 620c to apply an upward force F3 on the top planar wall 620c. The downward force F2 applied on the bottom planar wall 624c by the standoff member <NUM> and the upward force F3 applied on the top planar wall 620c securely clamps the interior support structure 608c within the frame body 604c of the level 600c. Adhesive may then be injected through the adhesive passageways 652c to permanently secure the interior support structure 608c to the frame body 604c. The center vial assembly 612c may then be inserted into the interior support cutout 634c, such that the projections <NUM> are received within the adhesive passageways 652c so as to secure the center vial assembly 612c in place on the level 600c via the adhesive.

A light source (e.g., an LED) may be positioned adjacent each of the first and second ends <NUM>, <NUM> of the vial <NUM> (or the vials 616b, 616c of <FIG>) to provide illumination within the vial <NUM>. The light sources emit light that reflects off the dark-colored outer portions <NUM> of the outer vial surround <NUM> (or the dark-colored bands <NUM>, <NUM> of <FIG>), and then either reflects off, or refracts through, the meniscus <NUM> of the bubble <NUM> to further increase the darkness of the meniscus <NUM> to provide improved contrast and visibility of the bubble within the vial <NUM>.

Claim 1:
A level (<NUM>) comprising:
a level body (<NUM>) defining a reference surface (<NUM>) configured to engage a workpiece;
a vial (<NUM>) supported by the level body (<NUM>) and including an inner surface (<NUM>) defining a cavity (<NUM>); and
a solid indicator (<NUM>) located within the cavity (<NUM>), the solid indicator (<NUM>) comprising:
a first surface (<NUM>) located at a first end of the solid indicator (<NUM>); and
a second surface (<NUM>) located at a second end of the solid indicator opposite the first surface (<NUM>);
wherein the solid indicator (<NUM>) moves within the vial (<NUM>) in response to changing angular positions of the level body (<NUM>), wherein the solid indicator (<NUM>) is shaped such that the first surface (<NUM>) and the second surface (<NUM>) are oriented in a direction perpendicular to the reference surface (<NUM>) when the reference surface (<NUM>) is oriented in a horizontal direction,
characterized in that the solid indicator (<NUM>) includes at least one rolling element (<NUM>) that supports the solid indicator (<NUM>) and that engages the inner surface (<NUM>) of the vial (<NUM>) such that the solid indicator (<NUM>) translates relative to the vial (<NUM>) via rolling of the rolling element (<NUM>, <NUM>) along the inner surface of the vial (<NUM>).