GB2269899A

GB2269899A - Alignment device

Info

Publication number: GB2269899A
Application number: GB9317477A
Authority: GB
Inventors: Michael John Smith
Original assignee: Individual
Current assignee: Individual
Priority date: 1992-08-21
Filing date: 1993-08-23
Publication date: 1994-02-23
Anticipated expiration: 2013-08-23
Also published as: GB9317477D0; GB2269899B

Abstract

An alignment or leveling device comprising a reel 11 on which a line 12 may be wound, and level sensing means 20 which may be at least partially suspended from the line adjacent to the reel. The level sensing means may include a spirit level tube 26 or other mechanical, electrical, or electronic level sensing element which may be rotatably mounted on the level sensing means so that it can be set to any desired angle. The level sensing means may be integral with or unclippable from a pivotable cradle (31, Fig 2) with pointer extension (32, Fig 1) aligned with the line, or may be a circle pivotable about a central point and having a large spirit level tube (26'', Fig 3A). The line 12 may be a tape or other form of line having distances marked off along it, or may pass over a measuring device. The reel may be any form of line storage means, but is preferably a spring-loaded self-rewinding reel. <IMAGE>

Description

Alignment Device The present invention relates to alignment devices of the type used in building, decorating, and like work. The commonest requirement for alignment is a levelling device, but there is often a need for an alignment device which can be set at some angle to the horizontal.

One technique is to use a pair of vertical transparent tubes containing a suitable liquid and linked by a communicating tube. However, the general bulk, fragility, and inconvenience of this is obvious.

The standard levelling device is therefore a spirit level. This consists essentially of a long straight piece of wood or extruded metal, with a slightly curved tube or "glass" set in it filled with a coloured liquid ("spirit") apart from a small bubble. When the level is horizontal, the bubble is centred in the glass; if the level is tilted, then the bubble is shifted away from the centre of the glass. A second glass may be set transversely in the level so that it can also be set vertically.

The simplest spirit levels only permit the determination of horizontality.

Many spirit levels, however, include two glasses, set at right angles, so that horizontality can be determined by observing one glass and verticality by observing the other. Greater generality can be achieved by mounting the glass in a disc which is rotatabIe and can be set at any desired angle. We will for convenience use terms such as "horizontal" and "levelling", but it will be understood that in general, we are actually concerned with setting to some given angle to the horizontal or vertical.

Such spirit levels are cheap and versatile. However, they suffer from a number of disadvantages. With a spirit level, for example, it must be possible to view the glass from above or the side; this makes it difficult to use much above eye level (say above 1.75 m).

If the direction of primary interest is the vertical rather than the horizontal, then a plumb line can of course be used instead. This is however not readily adapted for the determination of angles other than the true vertical; further, a plumb line must be free of obstructions, which makes it difficult to transfer its verticality to a fixed support.

The principle of the basic spirit level and/or plumb line has therefore been developed in a variety of ways, most of which involve the provision of some form of electrical or electronic sensing of horizontality or verticality.

A spirit level is typically somewhat less than 1 m long. This length is chosen as a compromise between a reasonable accuracy and giving extended alignment, on the one hand, and reasonable portability and the ability to be useable in small spaces, on the other. A level longer than 1 m would be inconvenient to carry around and would frequently not be useable for levelling small items; a level shorter than say 0.1 m would be inaccurate.

A spirit level has been proposed having a pair of sliding arms which extend to effective double the length of the level, but this is clearly only a partial solution to the problem.

A problem therefore arises when an alignment has to be extended for some considerable distance, of say some meters. What is normally done is to mark, on a suitable vertical surface, the level obtained from the spirit level, and then to extend this level. This requires a suitable surface to be available. It may be possible to extend a level set in this way by using a straight edge, if the vertical surface on which the level is marked extends as far as required. Alternatively, the level can be extended by means of a thin cord which is aligned with the level marked on the surface.

The alignment can of course be extended by means of a cord which is aligned directly with the spirit level. However, it is difficult to check the horizontality of such a cord, because it does not afford a firm support against which the level can be placed.

It has been proposed, in GB 2 138 134 A, to attach a small spirit level to the end of a cord; the spirit level has a hole at its other end, by means of which it can be attached to a fixed structure. By pulling on the cord, the spirit level is aligned with the cord, and the cord therefore extends the level established by the cord. This is however of limited practical use, since only the horizontal direction can be established, and also because the cord will rapidly become tangled when the device is not in use.

One possible "high-tech" solution to these problems is to incorporate a laser in a spirit level. This effectively extends the length of the spirit level indefinitely. However, it has various disadvantages. It is costly; the visibility of the laser beam along its length is low, and dependent on ambient conditions (so that it is less visible in bright light); and there are safety considerations associated with lasers.

In an attempt to avoid the complications of such "high-tech" techniques, there has been proposed, in WO 91/17410, an alignment device comprising a body with at least one reference face, extension means in the form of a cord having one end attached to the interior of the body and extending out through an aperture in the body, and mechanical, electrical, or electronic position sensing means mounted in the body for sensing and indicating any deviation of the angular position of the cord from a reference position relative to the reference face or faces, and preferably also including level sensing means for levelling the device.

The general object of the present invention is to provide an alignment or levelling device which is flexible and easy to use over considerable distances but is inexpensive.

According to the invention there is provided an alignment or levelling device comprising a reel on which a line may be wound, and level sensing means which may be at least partially suspended from the line adjacent to the reel.

The line may be a tape or other form of line having distances marked off along it, or may pass over a measuring device. The reel may be any form of line storage means, but is preferably a spring-loaded self-rewinding reel. The level sensing means may conveniently include a spirit level tube (though any convenient level sensing element, eg mechanical, electrical, or electronic, may be used).

The level sensing element is preferably rotatably mounted on the level sensing means so that it can be set to any desired angle.

In a nutshell, the present invention provides a device in which a cord can be extended from a reel or the like for use as an angular datum or reference for levelling applications.

Further significant features of the invention will become apparent from the following description of a levelling device and variations thereof in accordance with the invention, given by way of example and with reference to the drawings, in which: Fig. 1 is a diagrammatic view of the device; Fig. 2 is a diagrammatic view of a modification thereof; and Figs. 3A and 3B are diagrammatic views of a further modification thereof.

Referring to Fig. 1, the device consists of a casing 10 including a spool 11 and an adjustable level sensor 20. The spool 11 is mounted on the casing 10; the level sensor 20 may be carried loosely within the casing, or may be removably attached to the casing.

The spool 11 carries a cord 12, which may be wound up on the spool or unwound from it. The spool 11 may be of the spring-loaded self-rewinding type, preferably provided with a locking button (not shown), or may have a rewinding handle 14 as shown. The cord 13 has a hook 13 at its free end to allow it to be attached to a fixed point; if no suitable attachment point is available naturally, then a suitable point can generally be achieved by eg driving in a nail, or looping the cord round a suitable object and hooking the hook 13 over the running part of the cord.

The cord may be marked to indicate distances, and may be of flattened form, or may pass over some form of encoding or measuring wheel, mechanical, electrical, or electronic.

The level sensor 20 comprises a D-shaped frame having a semicircular portion 21 and a diametral bar 22, with the ends of the semicircular portion having holes 23 through which the line 12 passes. A radial bar 24 has one end hinged to a pivot 25 at the centre of the bar 22, and carries a bubble tube 26 mounted in it. The hinge is tight enough to hold the bar in whatever position it is moved to, but not so tight as to prevent it from being rotated around the hinge by finger pressure. The bar 24 can therefore be set to any desired angular position, and the semicircular portion 21 carries a scale which cooperates with a mark at the end of the radial bar 24 and allows that bar to be set to any desired angle.

The primary use of the device is to establish a line of desired inclination between two positions. For this, the end of the cord 12 is secured at one of the locations, as described above, and the bar 24 of the level sensor is set to the desired inclination. The device is then moved to the other location, with the cord unreeling from the spool 11. The device is pulled to put the cord under tension, with the level sensor 20 hanging freely on the cord. The device is then moved vertically until the bar 24 is horizontal, as indicated by the position of - the bubble in the bubble tube 26. The cord 12 is then at the required inclination.

When the required level has been established, the cord may be rewound on its spool using any convenient means, eg manual rewinding, a spring, or a suitable motor. If the spool mechanism maintains a substantial tension on the cord, the device can be used simply by holding the device so as to maintain the tension; alternatively, the spool may be provided with locking means, preventing the spool from unreeling any further and enabling a suitable tension to be put on the cord by manually pulling on the device as a whole.

The cord 12 may be lightly gripped by one or both of the holes 23, or by some convenient device between the holes, to prevent the level sensor 20 from sliding on the cord 12 if the line inclination is high.

The centre line of the two holes 23 must obviously be parallel to the bar 24 in its zero position (ie with the mark at its end pointing to 0 on the scale on the arc 21), but need not pass through the axis of the pivot 25. (The cord can be kinked out of the direct line between the holes.) The layout shown in Fig. 1 is somewhat diagrammatic, and a more practical layout is shown in Fig. 2. This layout is more compact, with the reel 11' being located above the level sensor 20'.To transfer the cord 12' from the reel 11' to the level sensor 20', it is passed round a pulley 30 as shown. (The level sensor 20' differs slightly from the level sensor 20 of Fig. 1, in that the line of the cord passes through the pivot axis 25' of the level sensor.) Further, the level sensor 20' is supported by a cradle 31, which is pivoted on the same axis as the pulley 30. This cradle has a pointer extension 32 which is aligned with the line of the cord 12' through the level sensor 20'. To use this device, the device as a whole is used to pull the cord 12' tight, and tilted until the bar 24' is horizontal (as indicated by the bubble in the bubble tube 26'). The pointer 32 can then be used to mark the line of the cord.

As so far described, the cradle 30 may be integral with the level sensor 20'.

The level sensor may however be attached to the cradle by means of clips 33, so that the level sensor can be unclipped from the cradle and moved out along the cord 12' if desired.

Figs. 3A and 3B show a further and more compact layout, Fig. 3A being a side view like Figs. 1 and 2 and Fig. 3B being a top view. In this device, the reel 11" is located behind the level sensor 20" instead of beside it as in the devices of Figs. 1 and 2. The cord 12" is carried from the reel 11" over a first pulley 41 into the plane of the level sensor 20" (strictly, into a plane slightly behind the plane of the main body of the level sensor). It is then carried over a second pulley 42 into alignment with the hole 23" in the level sensor. This second pulley is mounted on the same axis as the level sensor.

The level sensor 20" itself has a complete ring 21" instead of the semicircles of the level sensors of Figs. 1 and 2. Further, the bar 24" extends across the whole diameter of the ring 21", being pivoted at its centre point.

This allows the bubble tube 26" to be larger than in the Figs. 1 and 2 devices, or alternatively allows the whole device to be smaller. The bar 24" may have a pointer at one end and a vernier scale at the other end to allow the angle to be set accurately.

Obviously the shape of the frame of the level sensor can be varied, provided that it satisfies the functional requirements implied above. For example, it can be a solid D or circle (instead of an open D or circle with a diametral bar); it could also have a different outer boundary, eg square.

Claims

Clai x

1 An alignment or levelling device comprising a reel on which a line may be wound, and level sensing means which may be at least partially suspended from the line adjacent to the reel.

2 A device according to claim 1 wherein the line is a tape or other form of line having distances marked off along it.

3 A device according to claim l wherein the line passes over a measuring device.

4 A device according to any previous claim wherein the reel is a spring- loaded self-rewinding reel.

5 A device according to any previous claim wherein the level sensing means comprise a spirit level tube.

6 A device according to any previous claim wherein the level sensing element is rotatably mounted on the level sensing means so th.at it can be set to any desired angle

7 A device according to any previous claim wherein the level sensing means mounted on a cradle which is pivotally mounted on a base having the reel mounted on it.

8 A device according to claim 7 wherein the level sensing means is detachable from the cradle.

9 A device according to either of claims 7 and 8 wherein the cradle has a pointer aligned with the line through the level sensing means.

10 A device according to any previous claim wherein the reel is located substantially behind the level sensing means.

11 An alignment or levelling device substantially as herein described with reference to the drawings.

12 Any novel and inventive feature or combination of features specifically disclosed herein within the meaning of Article 4H of the International Convention (Paris Convention).