Boom pole

The present invention relates to a locking means (1) for use in releasably locking a first tubular structure (100) of a first diameter and a second tubular structure (101) of a second diameter in a predetermined position telescopically in relation to each other. The second diameter is less than the first diameter and the locking means comprises a component (2) adapted for gripping at least the second tubular structure and a component (5) adapted in use to cause the locking means to have a locked position in which the second tubular structure is held in place relative to the first tubular structure and an open position in which the second tubular structure is telescopically movable relative to the first tubular structure.

The present invention relates to boom poles, particularly for use with microphones. The invention is primarily concerned with telescopic boom poles.

Boom poles are used to allow a sound person to position a microphone, which is mounted on the boom pole, close to a sound source whilst allowing the sound person to be far enough from the sound source to avoid being seen on any camera recording the activities of the sound source.

The boom pole should be able to extend over a variety of distances, for example up to 2.5 m. The pole must therefore be collapsible, for example telescopic, to allow easy transportation between uses. Telescopic boom poles comprise at least two tubular structures, one of a diameter larger than the other such that they are sized to fit one inside the other in a telescoping arrangement. The means to join the telescoping structures and lock them in position for use must be strong and must hold the two tubular structures firmly in relation to each other. Furthermore the joining means must be suitably robust to withstand frequent use.

It is known to construct telescopic boom poles from aluminium or carbon fibre and in these known poles the tubular structures are aluminium or carbon fibre and the joining means between the tubular structures are usually aluminium. The joining means generally comprise a screw-threaded collar and collet arrangement associated with the tubular structure of larger diameter, which is provided with a screw threaded portion corresponding to the collar. The tightening of the screw-threaded collar onto the tubular structure of larger diameter causes the collet to grip the tube of smaller diameter.

There is however a problem with the use of aluminium to form the tubular structures in that it is not a particularly strong metal and boom poles made of aluminium are easily damaged and rendered useless. Carbon fibre is a stronger material but cannot be provided with an integral screw threaded portion and therefore requires the use of a separate joining means between the tubular structures. The currently available joining means are bonded to the tubular structures by an appropriate bonding agent, giving rise to a complex manufacturing process involving a number of steps and in which a number of parts must be manufactured and bonded together.

Accordingly there remains a need for a boom pole, particularly a carbon fibre boom pole, having a joining means that is simple and quick to assemble together with one or more tubular structures and does not require use of a bonding agent. It is also desirable that the joining means should secure one tubular structure strongly within another and should not loose strength over time.

Whilst this invention is described primarily in relation to boom poles it will be understood that it is applicable to telescopic poles used in other areas.

Accordingly the present invention provides a locking means for use in releasably locking a first tubular structure of a first diameter and a second tubular structure of a second diameter in a predetermined position telescopically in relation to each other, the second diameter is less than the first diameter and the locking means comprises a component adapted for gripping at least the second tubular structure and a component adapted in use to cause the locking means to have a locked position in which the second tubular structure is held in place relative to the first tubular structure and an open position in which the second tubular structure is telescopically movable relative to the first tubular structure,

wherein the gripping component comprises a first part sized and adapted in use to receive the first tubular structure and a second part extending from the first part and sized and adapted in use to receive the second tubular structure wherein the second part comprises two or more resilient fingers, and
the locking component extends around at least part of the gripping component and comprises means adapted in use to bring the resilient fingers into contact with the second tubular structure in the locked position.

The present invention further provides a combination of:

a first tubular structure of a first diameter,

a second tubular structure of a second diameter where the second diameter is less than the first diameter, and

a locking means for use in releasably locking the first tubular structure and the second tubular structure in a predetermined position telescopically in relation to each other;

the locking means comprises a component adapted for gripping at least the second tubular structure and a component adapted in use to cause the locking means to have a locked position in which the second tubular structure is held in place relative to the first tubular structure and an open position in which the second tubular structure is telescopically movable relative to the first tubular structure,
wherein the gripping component comprises a first part sized and adapted in use to receive the first tubular structure and a second part extending from the first part and sized and adapted in use to receive the second tubular structure wherein the second part comprises two or more resilient fingers, and
the locking component extends around at least part of the gripping component and comprises means to bring the resilient fingers into contact with the second tubular structure in the locked position.

The first part of the gripping component is preferably cylindrical in shape. The first part of the gripping component preferably has a first end portion that is open to receive the first tubular structure.

The first part of the gripping component preferably has an internal surface sized to fit around an external surface of the first tubular structure when in use. The first part of the gripping component is preferably adapted in use to fit around one end portion of the first tubular structure.

The second part of the gripping component preferably comprises two or more resilient fingers that extend away from the first part of the gripping component from the end of the first part distal from the first end portion. The fingers each preferably extend in a direction substantially parallel to a longitudinal axis running through the first part of the gripping component.

There may be provided two, three, four or more resilient fingers, it is preferred that there are three resilient fingers. The resilient fingers are preferably spaced apart from each other; most preferably they are spaced equidistant from each other.

One or more of the resilient fingers may be provided with a raised area on an external surface thereof. The raised area is preferably a cam surface.

The gripping component is preferably a hollow structure. The gripping component may be provided with lugs extending from an inner surface, most preferably of the first part, adapted in use to locate in indentations provided in the first tubular structure.

The locking component preferably comprises a collar that extends around the gripping component and contacts at least part of an outer surface of the gripping component.

The collar is preferably rotatable relative to the longitudinal axis of the gripping component. The collar is preferably secured to the gripping component such that it is rotatable relative to the longitudinal axis of the gripping component.

The collar preferably has a first end and a second end. The collar is preferably provided with a first set of one or more cam surfaces positioned on an inner surface such that one or more of the cam surfaces contacts at least one of the two or more resilient fingers when the collar is in the locked position. Preferably the or each cam surface contacts a raised area, or cam surface, provided on the resilient finger.

Preferably there is provided one cam surface positioned in use to act on each resilient finger. The first set of one or more cam surfaces is preferably positioned close to the first end of the collar.

In a preferred embodiment the first part of the gripping portion is provided with one, two or more cut away portions extending parallel to the longitudinal axis of the gripping component. Therefore the first part is provided with two or more resilient arms separated by the cut away portions. The arms are preferably each provided with raised areas positioned on an external surface thereof. The raised areas are preferably cam surfaces.

In this preferred embodiment the collar of the locking component is provided with a second set of one or more cam surfaces positioned on its inner surface such that one or more of the cam surfaces contacts at least one of the two or more resilient arms when the collar is in the locked position. The second set of cam surfaces is preferably provided close to the second end of the collar. The second set of cam surfaces preferably engages the raised areas, or cam surfaces, of the arms when the collar is in the locked position. Preferably there is provided one cam surface positioned in use to act on each resilient arm.

The collar is preferably also provided with one, two or more cut away portions preferably extending parallel to the longitudinal axis of the collar. The cut away portions are preferably provided on the second end of the collar. The cut away portions allow the second part of the collar to move out of contact with the raised areas of the arms of the first portion when it is rotated into the unlocked position. The cut away portions also ensure that there is direct action between the first set of one or more cam surfaces and the resilient fingers. The presence of the cut away portions also means that the action between the second set of one or more cam surfaces and the resilient arms is a secondary action and relies on the spring effect of the collar.

Preferably the tubular structures are made from carbon fibre. The gripping component and the locking component of the locking means are preferably made from a suitable mouldable material, such as a mouldable plastics material, for example acetal.

The locking means of the present invention is advantageous in many ways. It is simple in its design and the components are easy to manufacture by standard moulding techniques, such as injection moulding. The locking means can be manufactured from standard mouldable plastics materials.

The locking means is robust and easy and quick to use. It is only necessary to rotate the locking component through a small number of degrees to move from the open to locked position and back again compared to standard collar and collet locking means which must be rotated through several complete turns to lock and open.

The locking means can be manufactured in any suitable size depending on the size of the tubular structures with which it is to be used.

The gripping component does not require any bonding agent to secure it to the first tubular structure but is held in place by the first part locating on an end portion of the tubular member and ideally the provision of lugs on the first part of the gripping component, which are received by corresponding indentations in the tubular structure.

In the most preferred embodiment the action of the second set of cams of the locking component further assists in securing the gripping component to the first tubular structure such that it is firm and does not wobble. In the field of microphone technology any vibration is undesirable and should be eliminated as it can impact on the sound quality of the microphone. The use of the second set of cams surfaces prevents movement and wobble of the locking means.

The action of the first set of cam surfaces on the resilient fingers of the second part of the gripping component gives rise to a strong grip on the second tubular structure holding it in the desired position.

The locking means is hollow and generally tubular in nature, which means that the cable of a microphone can be fed down the formed boom pole without any obstruction.

FIG. 1shows a locking means1comprising a gripping component2, having a first part3and a second part4, and a locking component5. The locking component5is secured to the gripping component2such that it is rotatable in relation to the gripping component2. Also shown inFIG. 1are a first tubular structure100and a second tubular structure101.

The first tubular structure100has a first end100aand a second end100b. The first end100areceives the first part3of the gripping component2. The second end receives the second tubular structure101.

The second tubular structure101has a first end101aand a second end101band is of a suitable diameter to be telescopically received within the first tubular structure100and to pass through the second part4of the gripping component2.

The second tubular structure101is provided with tapes102a,102baround its second end101bto ensure that the second end is a snug fit inside the first tubular structure100and undesirable movement and associated noise is eliminated. The tape102aclosest to the first end101aof the second tubular structure101also acts to prevent the second tubular structure101from passing all the way through the first tubular structure100as will be explained further in relation toFIG. 3.

FIG. 2shows in detail the gripping component2ofFIG. 1. The gripping component has a first part3and a second part4.

The first part3is generally cylindrical in shape and has a first end3athat is open to receive the first tubular structure100, shown inFIG. 1. The first part3therefore has a first diameter suitable to receive the first tubular structure100. The inner surface of the first part3is provided with a number of protruding lugs20which are received in corresponding indentations (not shown inFIG. 2) in the first end100aof the first tubular structure100.

The first part3has three elongate slots21formed along part of its length and extending from the first end3ato give rise to the formation of three arms22. Each arm22is provided with a raised area forming a cam surface23on its outer surface.

There is provided an outwardly extending lip22aformed on each of the arms22to give rise to a rim formed in three parts around the end3aof the first part3.

The second part4of the gripping component2comprises three fingers24extending from the first part3at its end distal from the first end3a. The fingers24are arranged to form a generally cylindrical structure and are equidistantly spaced apart from each other. There is an inward step26in the external profile of the gripping component2caused by the diameter of the second part4being smaller than that of the first part2.

The fingers24are each provided with raised surface portions forming cam surfaces25on their outer surfaces. The fingers24are also each provided with outwardly extending lips24aon their free ends.

The gripping component2is generally cylindrical in its overall shape and is therefore hollow. The gripping component2is formed from a resilient plastics material. The gripping component is injection moulded from that material.

FIG. 3shows the gripping component2in use in combination with the locking component5to releasably lock the second tubular structure101in a predetermined position in relation to the first tubular structure100.

The locking component5is a generally cylindrical collar that is secured in relation to the gripping component by being provided with cut away shoulders51a,51bthat rest against the lips22a,24aof the gripping component respectively. The locking component5is rotatable by 10°-90° around the outer surface of the gripping component2.

The locking component5has a first end portion5aand a second end portion5b. The first end portion5alies adjacent the second end part4of the gripping component2and the second end portion5blies adjacent the first part3of the gripping component2.

The locking component5is provided with two sets of cam surfaces extending from its inner surface. The first set of cam surfaces30is provided close to the first end5aof the locking component5. The cam surfaces30are positioned and sized to contact the cam surfaces25of the fingers24when the locking component5is in the locked position. The cam surfaces30are also positioned and sized to be in incomplete contact with the cam surfaces25of the fingers24when the locking component5is in the open position. There are therefore three cam surfaces30spaced equidistantly around the inner surface of the first end5aof the locking component5.

The second set of cam surfaces31is provided close to the second end5bof the locking component5. The cam surfaces31are positioned and sized to contact the cam surfaces23of the arms22when the locking portion is in the locked position. The cam surfaces31are also positioned and sized to be in incomplete contact with the cam surfaces23of the arms22when the locking component5is in the open position

The second end portion5bof the locking component5is provided with a number of elongate cut away portions (not shown) extending along its length to allow movement of the locking component between locked and open positions.

The locking component is made from a resilient plastic material and ideally is injection moulded from that material.

In use to assemble the first and second tubular structures and the locking means for the first time the locking means1is secured to the first tubular structure100by receipt of the first end100aof the first tubular structure within the first part3of the gripping component2and engagement of the lugs20in apertures provided in the first tubular structure100.

The locking component5is then passed over the gripping component2, with the second end portion5bleading and passing firstly over the second end4of the gripping component, until the shoulder51aof the second end portion5babuts the lip22aof the first part3and the shoulder51bof the first end portion5arests against the lip24aof the second part4. To allow the locking component5to pass over the gripping component2the fingers24of the second end part4are squeezed together until the locking component5is in position relative to the gripping component2.

The first end110aof the second tubular structure101is then passed into the second end100bof the first tubular structure100and through the channel defined by fingers24of the second part4of the gripping component2. The presence of the second tubular structure101in the channel defined by the fingers24prevents the fingers24of the second part4of the gripping component2from being squeezed together sufficiently to allow removal of the locking component5from its position around the gripping component2.

Tape102aprovided around the second tubular structure101, closest to the first end of the second tubular structure101, acts to prevent the second tubular structure101from passing straight through the first tubular structure100. The tape102aabuts the stepped portion26of the gripping component2where the fingers24extend from the first part3and is suitably sized not to be able to pass through the stepped portion26of the gripping component2.

Once the first and second tubular structures and the locking means have been assembled the second tubular structure can be telescopically moved in relation to the second tubular structure and there is no need to disassemble the structure for storage or transport it can simply be telescopically contracted to a small and manageable size.

To secure the second tubular structure101in a predetermined position relative to the first tubular structure100the locking component5of the locking means1is rotated through 10°-90°, preferably 30°-45°, to bring the first set of cam surfaces30into position over, and therefore in contact with, the cam surfaces25of the fingers24. This action presses the fingers24against the second tubular structure101to hold it in position.

The engagement of the first set of cam surfaces30with the cam surfaces25of the fingers24on rotation of the locking component5causes the second set of cam surfaces31of the locking component5to apply pressure to the cam surfaces23of the arms22. The elongate cut away portions in the second end portion5bof the locking component5allow movement of the first end5aof the locking component5to force the second end5bof the locking component5to expand away from its usual position. The resilient material used to form the locking component5ensures that the second end5btries to regain its original shape and size and therefore the second end5bexerts pressure on the arms22of the first part3of the gripping means2, through the action of the cam surfaces on these parts, which in turn exert pressure on the first tubular structure100.

This double cam action ensures that the locking means5works in relation to both tubular structures100,101thus reducing or eliminating movement and any associated noise and giving a strong joint. Injection moulding of the locking means and the material used makes the manufacture of the locking means cost effective. The way in which the locking means is secured to the first tubular structure makes this action quick and simple.