Measurement device

A measurement device comprising a curved container containing a liquid, a first indicator that is less dense than the liquid, and a second indicator that is more dense than the liquid, where the liquid substantially fills the container so that the position of the first indicator and/or second indicator in the container relative to the reference indicia may indicate an angle-related property of the device.

RELATIONSHIP TO OTHER APPLICATIONS

The present application claims the benefit of and priority to UK application GB1210918.7 filed 20 Jun. 2012, which is hereby incorporated by reference.

FIELD OF THE INVENTION

This invention relates to a measurement device, and more particularly to a measurement device for measuring angle-related properties determined by the orientation of the device.

BACKGROUND

There are various known methods of measuring the inclination of surfaces which include optical measurement tools and complicated measurement tools.

One of the simplest tools for measuring the inclination of a surface is the spirit level (sometimes known as a bubble level). A spirit level device typically includes a longitudinal container which contains a liquid and a “bubble” of a material having a lower density than the surrounding liquid. Due to the relative densities of the bubble and the surrounding liquid, the bubble always tends to rise relative to the liquid, in accordance with Archimedes' principle, to its highest local point relative to the gravitational vertical axis as determined by the confines of the container. Therefore, if there is any inclination in the longitudinal container, the buoyant forces acting on the bubble cause it to rise in the liquid towards its highest gravitational point permitted by the container. Thus, a user will be able to determine whether the surface that the spirit level is resting on or held against has an inclination or not by the behavior of the bubble. The spirit level may include reference lines to assist the user in monitoring the position and any movement of the bubble.

The spirit level is therefore a very simple, yet effective, device for indicating the presence of an inclination. However, a spirit level such as the one described above is incapable of indicating the extent of the inclination beyond the horizontal plane and is therefore of limited use when more detailed and specific information is required.

It is an object of the present invention to provide a measurement device that is capable of indicating that a surface has an inclination and that is additionally capable of providing more specific angle-related information about the extent of the inclination.

BRIEF SUMMARY OF THE DISCLOSURE

General Representations Concerning the Disclosure

This specification incorporates by reference to the fullest extent allowable by law all documents referred to herein and all documents filed concurrently with this specification or filed previously in connection with this application, including but not limited to such documents which are open to public inspection with this specification.

In this specification, reference is made to particular features of the invention. It is to be understood that the disclosure of the invention in this specification includes all appropriate combinations of such particular features. For example, where a particular feature is disclosed in the context of a particular embodiment or a particular claim, that feature can also be used, to the extent appropriate, in the context of other particular embodiments and claims, and in the invention generally. The embodiments disclosed in this specification are exemplary and do not limit the invention. Other embodiments can be utilized and changes can be made. As used in this specification, the singular forms “a”, “an”, and “the” include plural reference unless the context clearly dictates otherwise. Thus, for example, a reference to “a part” includes a plurality of such parts, and so forth. The term “comprises” and grammatical equivalents thereof are used in this specification to mean that, in addition to the features specifically identified, other features are optionally present. The term “consisting essentially of” and grammatical equivalents thereof is used herein to mean that, in addition to the features specifically identified, other features may be present which do not materially alter the claimed invention. The term “at least” followed by a number is used herein to denote the start of a range beginning with that number (which may be a range having an upper limit or no upper limit, depending on the variable being defined). For example “at least 1” means 1 or more than 1, and “at least 80%” means 80% or more than 80%. Where reference is made in this specification to a method comprising two or more defined steps, the defined steps can be carried out in any order or simultaneously, and the method can optionally include one or more other steps which are carried out before any of the defined steps, between two of the defined steps, or after all the defined steps. Where reference is made herein to “first” and “second” features, this is generally done for identification purposes; unless the context requires otherwise, the first and second features can be the same or different, and reference to a first feature does not mean that a second feature is necessarily present (though it may be present). Where reference is made herein to “a” or “an” feature, this includes the possibility that there are two or more such features (except where the context excludes that possibility).

In accordance with a first aspect of the present invention there is provided a measurement device comprising:

a curved container containing a liquid, a first indicator that is less dense than the liquid, and a second indicator that is more dense than the liquid, where the liquid substantially fills the container;

wherein the first indicator is free to move in the liquid to its highest local point relative to the gravitational vertical axis as determined by the confines of the container, and the second indicator is free to move in the liquid towards its lowest local point relative to the gravitational vertical axis as determined by the confines of the container; and wherein the measurement device further comprises reference indicia arranged relative to the container so that the position of the first indicator and/or second indicator in the container relative to the reference indicia may indicate an angle-related property of the device.

Given that the first indicator is less dense than the liquid, its movement to its highest local point (relative to the gravitational vertical axis) will be caused by the upward buoyant forces acting on the first indicator exceeding the downward gravitational forces. Conversely, given that the second indicator is denser than the liquid, its movement to its lowest local point (relative to the gravitational vertical axis) will be caused by the downward gravitational forces exceeding the upward buoyant forces acting on the second indicator.

In one preferable embodiment, the curved container follows a circular path, wherein the circular path preferably extends along an arc subtending an angle greater than 180°. Additionally or alternatively, the circular path extends along an arc subtending an angle less than 360°. In one preferable embodiment, the circular path extends along an arc subtending an angle between 180° and 200°.

The measurement device may further comprise a frame wherein the curved container is attachable to the frame. In one embodiment, the reference indicia are arranged on the frame. The frame and the reference indicia may be arranged so that the reference indicia are viewable from an angle that is substantially along the plane of the container.

The curved container may be attachable to the frame by a snap fit arrangement.

In one preferable embodiment, the first indicator is a gas. Additionally or alternatively, the second indicator is a solid.

In accordance with a second aspect of the present invention there is provided a kit comprising:

a curved container containing a liquid, a first indicator that is less dense than the liquid, and a second indicator that is more dense than the liquid, where the liquid substantially fills the container, wherein the first indicator is free to move in the liquid to its highest local point relative to the gravitational vertical axis as determined by the confines of the container, and the second indicator is free to move in the liquid towards its lowest local point relative to the gravitational vertical axis as determined by the confines of the container; and

a plurality of frames, wherein the container is removably attachable to each of the plurality of frames;

wherein each of the plurality of frames includes reference indicia so that when each of the frames is individually attached to curved container, the reference indicia are arranged relative to the container so that the position of the first indicator and/or second indicator in the container relative the reference indicia may indicate an angle-related property of the container.

DETAILED DESCRIPTION

FIG. 1shows a measurement device10in accordance with an embodiment of the present invention. The measurement device10includes a curved container12that follows a circular path. The container12is attached to a frame14that provides structural rigidity to the device10and provides a more substantial structure for a user to handle. Additionally, the frame14has a flat edge14athat is flush with flat ends12aof the container12. The flat edge14aand flat ends12aof the container12lie along a chord of the notional circle about whose circumference the container12extends.

The container12contains a liquid16that fills almost all of the internal volume of the container12. Additionally, the container includes a first indicator18that is less dense than the liquid16, and a second indicator20that is denser than the liquid16. The first indicator18and second indicator20have relatively small volumes that are much smaller than the volume of the liquid16. In one example, the first indicator18is a liquid that is less dense than the surrounding liquid16. In an alternative example, the first indicator18is a gas that is less dense than the surrounding liquid16. Similarly, in one example, the second indicator20is a liquid that is denser than the surrounding liquid16. In an alternative example, the second indicator20is a solid that is denser than the surrounding liquid16, such as a metallic ball. The first indicator18and second indicator18move in the container12relative to the liquid16according to gravitational and buoyant forces. The first indicator18and second indicator20may be chosen to have low frictional resistance when moving through the liquid16. The liquid16may be coloured to assist visibility of the first indicator18and/or second indicator20.

Thus, the first indicator18tends to move towards its highest local point in the container12as the first indicator18experiences an upward buoyant force in the liquid16that is greater than the downward gravitational force acting on the mass of the first indicator18. In this context, the relative terms “higher” and “lower” and the like are considered to be relative to the gravitational vertical axis. Throughout this application, therefore, the terms highest/lowest local/global gravitational point are used to indicate points relative to the gravitational vertical axis (i.e. the line along which gravity acts) regardless of whether the downward gravitational force or upward buoyant force is dominant. The skilled reader will appreciate that the word “local” is used in the term “highest local gravitational point” to indicate that the highest point reachable by the first indicator18in the container12may not be the highest (global) point of the container12, as is described in more detail below.

Similarly, the second indicator20tends to move towards its lowest local gravitational point in the container12as the second indicator20experiences a downward gravitational force that is greater than the upward buoyant force in the liquid16. Again, the skilled reader will appreciate that the word “local” is used in the term “lowest local gravitational point” to indicate that the lowest point reachable by the second indicator20in the container12may not be the lowest (global) point of the container12, as is described in more detail below.

In each ofFIGS. 1 to 4, the direction g indicates the downward line along which gravity acts on the device10and its components. That is, direction g is parallel to the gravitational vertical axis referred to above.

The container12is configured so that the first indicator18and second indicator20are viewable through at least a portion of the container12. Additionally, the container12is sealed (but not necessarily irreversibly so) so as to prevent the liquid16, first indicator18and second indicator20from exiting the container12. The container12may be a vial and/or may be made from any one or more of glass, Perspex, PVC, or other suitable material. In one embodiment, the container12is made of a semi-rigid or flexible plastics material.

Considering the measurement device10in the orientation shown inFIG. 1, where the flat ends12aof the container12and the flat edge14aof the frame14are disposed horizontally (i.e. perpendicularly to direction g) and the flat ends12aare beneath the remainder of the container12, the first indicator18is positioned at its highest local gravitational point in the container12. Indeed, in the orientation shown inFIG. 1, the first indicator18is also in the highest global gravitational point within the container12, since no part of the internal volume of the container12is higher than the point where the first indicator18is disposed. The highest local gravitational point and the highest global gravitational point for the first indicator18will be coincident for orientations within +/−90° of the orientation shown inFIG. 1(rotated about a point at the center of the notional circle about whose circumference the container12extends along).

The measurement device10includes reference indicia22which may include markings, graduations, symbols or other indicia for indicating an angle-related property of the device10. In use, the user may deduce the angle-related property of the device10by assessing the position of the first indicator18or second indicator20relative to the reference indicia22. For example, in the orientation shown inFIG. 1, the position of the first indicator18relative to the reference indicia22may indicate that the measurement device10is orientated horizontally. More particularly, if the measurement device10ofFIG. 1is disposed with the flat edge14aof the frame14and the flat ends12aof the container12disposed on a surface, the position of the first indicator18relative to the reference indicia22may indicate that the surface is horizontal.

The first indicator18is configured to indicate (by reference to its position relative to the reference indicia22) an angle-related property of the measurement device10within +/−90° of the orientation shown inFIG. 1. Beyond +/−90° of the orientation ofFIG. 1, the highest local gravitational point of the first indicator18will be towards one of the ends12aof the container12and will be unchanging such that the usefulness of information provided by the first indicator18is limited. Instead, at orientations beyond +/−90° of the orientation ofFIG. 1, the position of the second indicator20relative to the reference indicia is used to provide an indication of an angle-related property of the device10. Indeed, at these orientations, the lowest local gravitational point of the second indicator20is coincident with the lowest global gravitational point for the second indicator20within the container12, since no point of the container12is lower than where the second indicator20is disposed.

FIG. 3shows the measurement device10in an orientation that is rotated θ° relative to the orientation shown inFIG. 1. In use, this may be because the device10is positioned on a surface that is angled θ° from the horizontal. The first indicator18has moved relative to its position shown inFIG. 1to its new highest local (and global) gravitational point. The position of the first indicator18relative to the reference indicia22may be used to indicate an angle-related property of the device10. For example, the reference indicium22proximate the first indicator18may be labeled θ° to explicitly indicate the orientation of the device10or the inclination of a surface on which the device10is disposed, where θ is the angle corresponding to the inclination of the device10.

Similarly, inFIG. 4the device10is orientated at θ° relative to the orientation shown inFIG. 2. In this orientation, the second indicator20is the actively useful indicator (of the two indicators18,20) and travels under the influence of gravity to its lowest local (and global) gravitational point. The position of the second indicator20relative to the reference indicia22may be used to indicate an angle-related property of the device10. For example, the reference indicium22proximate the second indicator20may be labeled θ° to explicitly indicate the orientation of the device10or the inclination of a surface on which the device10is disposed, where θ is the angle corresponding to the inclination of the device10.

It should be noted that in the orientation shown inFIG. 4, the first indicator18is at its highest local gravitational point but this is not coincident with the highest global gravitational point as there are parts of the container12that are disposed higher than the first indicator18. However, the first indicator18must first travel downwards (gravitationally) in order to reach the highest global gravitational point. Since the first indicator18is unable to do this under the influence of buoyancy and gravity alone, the first indicator18remains “trapped” at its highest local gravitational point. Nevertheless, the first indicator18is redundant in this orientation and the “active” second indicator20provides useful information to the user by virtue of its position relative to the reference indicia22.

As demonstrated by the examples described above with reference toFIGS. 1 to 4, the measurement device10of the present invention may be used to measure or indicate angle-related properties of the device10(or a surface to which the device10is aligned). The measurement device10may be used in any orientation within a substantially vertical plane, where either the first indicator18or the second indicator20is active in providing useful information depending on the orientation of the device10. When the measurement device10is used to measure angle-related properties of a surface, the first indicator18is active when measuring the upper side of the surface (such as a table-top, for example), and the second indicator20is active when measuring the under side of the surface (such as a ceiling, for example). Thus, the measurement device10is capable of measuring through 360°.

The reference indicia22may be chosen to provide information to the user in respect of various angle-related properties, such as, but not limited to, scales, graduations, degrees, and key gradient indicators. For example, the reference indicia22may indicate absolute angles (in units such as degrees or radians) in relation to the vertical or horizontal. Alternatively, the reference indicia22may indicate a gradient quantity. In a further alternative embodiment, the reference indicia22may indicate a descriptive property indicating a region of ideal or acceptable angles. In particular, for a specific application, the reference indicia22could include labels such as “Too Steep”, “Too Shallow”, and “Acceptable”, or similar, or could have coloured or otherwise distinguishable regions indicating various angle-related properties. The skilled reader will appreciate that any suitable angle-related reference indicia22may be used within the scope of the present invention and that the reference indicia22may be customized for specific applications of the measurement device10.

In one preferable embodiment, the container12is attachable to the frame14by a snap fit arrangement or the container12may be inserted into the frame14. The container12is preferably removably attachable to the frame14. In one particularly preferable embodiment, the container12is provided as part of a kit with one or more frames14where the frames14may have different reference indicia22for various different applications. The container12may then be attached to any of the frames14for the desired application.

The reference indicia22may be on the frame14. However, in alternative embodiments, the measurement device10may not include a frame14and/or may have the reference indicia22on the container12itself. The reference indicia22may be etched, painted or otherwise marked on the frame14or the container12. The reference indicia22may be disposed on the more radially inward part of the container12in which case the curvature of the container12may provide a magnifying effect when the reference indicia22are viewed from a more radially outward position. In another embodiment, the reference indicia22may be disposed on the more radially outward part of the container12. This arrangement may avoid optical distortion since the reference indicia22do not need to be viewed through the container12(and hence liquid16). Hence, it may be the case that the accuracy of the device may be optimized.

In one particularly preferable embodiment, the reference indicia22are viewable from an angle that is substantially along the plane of the container12so that a user using the device10in a vertical plane (as is intended) and viewing the device10from a position directly vertically above or below the device10is able to easily determine the angle-related property of interest. To achieve this, the reference indicia22could be disposed on the container12so that they are viewable from an angle that is substantially along the plane of the container12or the frame14could be arranged around the container12so that it is able to exhibit the reference indicia22along the plane of the container12and still leave at least a portion of the container12visible so that the first indicator18and/or second indicator20is viewable through the container12.

The container12need not necessarily follow the arc of a circle, however this arrangement is preferable. Indeed, the container12may take on other non-linear (i.e. curved) configurations. Non-linear arrangements prevent the container acting like a standard spirit level where the indicator would travel unimpeded to one of the ends of the container for any inclination, thus providing no useful information other than indicating the presence of an inclination. Examples of non-linear, non-circular paths that the container12may follow include, but are not limited to, elliptical and hyperbolic formations. Useful reference indicia22can be applied to the measurement device10that has been calibrated or otherwise calculated to indicate the desired angle-related properties by reference to the position of the first indicator18and/or second indicator20.

The container12preferably extends along the arc of a circle that subtends an angle greater than 180°. The benefit of this arrangement can be appreciated by considering a measurement device10having a container12that extends along the arc of a circle that subtends an angle of 180°. In this arrangement, if the device10was held so that the flat edge14aof the frame is aligned vertically (along direction g), the first indicator18and second indicator20would be disposed at (opposite) ends of the container12. Because the first indicator18and second indicator20are not point elements but finite in size, there will be little difference, if any, in the position of at least one of the first indicator18and second indicator20relative to the reference indicia22compared with a position in which the device10is rotated by a small amount, such as 1° or 2°, for example. Therefore, by providing a container12that extends along an arc of a circle that subtends an angle greater than 180°, more accurate measurements are possible for orientations around absolute vertical and absolute horizontal. The container12preferably extends along an arc of a circle that subtends an angle less than 360° so that the container12can terminate at flat ends12aproviding a flat edge that can be disposed on a surface to be measured.