GB2408316A

GB2408316A - Collapsible photographic reflector

Info

Publication number: GB2408316A
Application number: GB0327073A
Authority: GB
Inventors: Manh Han
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-11-21
Filing date: 2003-11-21
Publication date: 2005-05-25
Also published as: GB0327073D0

Abstract

A collapsible photographic lighting reflector comprises a collapsible frame supporting an expanse of reflective, flexible material 1. The frame may include hinged 18 two-piece ribs 11 which are retained to a central aluminium ring 10 by pivots (2, fig 3) which are carried outside the outer circumference of the ring, allowing the umbrella to be folded compactly for transportation without placing additional stress on the attached ribs. A central aperture in the ring may accommodate a connection element (8, fig 2B) which is engageable with a thermally conductive aluminium lock ring 7 for attachment of a rear mounted light source eg. flash tube 4 and incandescent bulb 5, a flat mounting plate with a rear bracket may be substituted for the connection element or the ring, and a front mounted light source carried instead on elongate rods extending from the mounting plate or from the front of the ring. The connection element or mounting plate may be quickly assembled to the ring by means of spring loaded catches to form a rotating clutch. The absence of internal struts for supporting the ribs helps to avoid the formation of shadows.

Description

24083 1 6 Photographic Softbox or Lighting Umbrella This invention relates

to collapsible photographic lighting reflectors, often referred to as softboxes or lighting umbrellas.

Softboxes or lighting umbrellas are used in photography for reflecting and directing light from an associated light source, which is commonly a flashbulb or strobe light, an incandescent bulb, or a combination thereof, onto the subject or background of the photograph. A softbox comprises an expanse of fabric or other flexible material having a reflective inner surface, which is stretched by means of a collapsible frame to form a dished or boxlike structure defining a large light emitting opening. A translucent panel or diffuser may be arranged over the light emitting opening to adjust the quality of the emitted light. in this specification the terms "softbox" and "lighting umbrella" are used interchangeably.

A simple type of lighting umbrella is commonly found in smaller sizes, and resembles a conventional umbrella with radial ribs supported by shorter inner struts which are braced against a sleeve which slides axially along a central pole or handle. The light body carrying the light source is supported on a stand or the like and the umbrella is attached next to the light source by means of the central pole which extends from the light emitting opening. US 5,023,757 to Shirilla discloses a lighting umbrella of this type wherein the inner struts are covered by a reflective lining to prevent the formation of shadows.

For more effective and convenient lighting, especially of larger areas, softboxes are available which include an integral mounting for the light source as well as means for supporting the umbrella or the light source on a stand arranged at the back of the umbrella behind the reflective surface.

A softbox of this more sophisticated type and defining a generally rectangular light emitting opening is illustrated by WO 02/18839 to Shirilla, and provides an annular backplate or central frame element which has a central opening which accommodates the light source and a set of ribs carried on hinges arranged around the opening. A fabric cover is arranged over the ribs, and may be stretched into the open position by pivoting the distal ends of the ribs outwardly and locking them into place by means of shorter inner struts. Each inner strut is hinged at one end to an intermediate point on one of the ribs, and at the other to a central connector which slides axially along a central post supported on the backplate.

The mechanism thus resembles a conventional umbrella.

A similar mechanism is disclosed by CH 645 735 to Elinca, which provides a generally umbrella shaped softbox wherein the ribs are hinged at their proximal ends on a backplate provided with a large central handle. Each rib is attached at an intermediate point to one of a set of shorter inner struts, which are hinged at their proximal ends to a central ring provided with a central opening for accommodating the light source. The umbrella is deployed by grasping the handle of the backplate and pulling it outwards towards the central ring, forcing the inner struts outwards against the resilience of the ribs, until a set of posts extending from the backplate engage with a spring loaded latch mechanism in sockets mounted on the ring in order to lock the inner struts in place.

Softboxes two metres or more in length or diameter are commonly in use, and the user of either of the last mentioned softboxes may find that, depending on the size of the umbrella, substantial force is required to deploy all of the ribs simultaneously. They can also be inconvenient to transport. A further disadvantage is found in practice in that the inner struts, being interposed between the reflective inner surface and the light emitting opening of the softbox, tend to cast an unwanted shadow or "ghost" image onto the subject.

EP 0 964 291 to Elinca discloses a softbox wherein each rib is inserted into a socket which is hinged to the central frame element. The user may thus extend the ribs one by one by pivoting each socket out from the central frame element and locking it in position with a spring loaded sleeve.

The light source of the softbox, which may comprise one or more glass bulbs or lamps, is mounted on a light body which provides mechanical and electrical connections and may have a trailing lead or alternatively a socket for connection to the power source, and perhaps a shade or reflector around part of the light source. A large variety of light bodies are commercially available from a number of different manufacturers, and each light body is commonly provided with a lock ring, which is a generally annular element arranged around the light source and is usually rotatable to engage a corresponding connection ring or sleeve on a softbox, reflector or other device as required.

In order to facilitate connection to a variety of different light bodies, softboxes are commonly provided with an interchangeable connection ring, which is usually a flanged sleeve which extends from the frame of the softbox around the opening for the light source and engages the corresponding lock ring on the light body. A popular type of connection ring provides a "bayonet" or push-and-twist pattern wherein the connection ring has two cranked slots on opposite sides of the sleeve and the lock ring has an annular groove containing two cooperating lugs. The connection ring may be arranged to rotate relative to the softbox frame so that, when the light body is clamped to a supporting stand behind the softbox, the softbox may be rotated around its connection ring so as to optimally direct the reflected light. Retaining screws or "lockdowns" are commonly provided for this purpose, which may be loosened to permit rotation.

Softboxes of larger sizes may use light sources of 20kW or more power, which may include both a flash or strobe light source which is energised at the moment the photograph is taken, and an associated incandescent "pilot" or "modelling" bulb of lower power which is constantly energised. A substantial amount of heat is often generated by the light source, and during intensive use this can lead to melting of the fabric of the umbrella as well as of the lock ring, which is commonly made from plastics material and extends inside the connection ring to surround the light source.

A further problem is found in that the reflective front surface of the fabric is commonly formed by a laminated, aluminised layer, and tends to delaminate with wear, which is exacerbated by abrasion by the stressed ribs of the umbrella. The distal ends of the ribs also tend to work through the margin of the fabric around the light emitting opening, requiring reinforcement and repair.

It is also found in practice that with many commercially available softboxes, the central frame element which holds the proximal ends of the main ribs in spaced apart relationship, and which is generally formed as an aluminium ring, tends to deform or shatter if it is dropped or abused. This is particularly problematic since the larger and more sophisticated types of softbox are generally used in professional studio or location situations and are frequently hired out by specialist suppliers, and it is therefore desirable that they should be as robust as possible.

Preferably such softboxes should also be quick and easy to deploy and to pack away, and as versatile as possible so as to accommodate a variety of alternative light sources depending on the photographic situation. It is also important however that they should be as simple as possible in use, so as to obviate the risk of losing component parts or of interchanging similar but incompatible parts when a number of users are working together with a variety of softboxes.

It is the object of the present invention to provide a softbox which is convenient, effective and robust in use.

According to a first aspect of the present invention there is provided a collapsible photographic light reflector comprising an expanse of flexible material and a collapsible frame, the material having a rear surface, a reflective front surface and an outer peripheral edge; the frame including a plurality of ribs, each rib having a s proximal end region and a distal end region, a central frame element having an outer periphery and supporting the proximal end regions of the ribs, and attachment means for connecting the frame to a light body carrying a light source; the ribs being pivotably supported by the central frame element so as to be adjustable between a deployed position and a folded position, the distal end regions of the ribs engaging the material in the region of its outer peripheral edge such that in the deployed position the outer peripheral edge of the material defines a light emitting opening, the reflector including locking means for locking the ribs in the deployed position; characterised in that the frame includes a plurality of radial extension pieces, each radial extension piece being supported by the central frame element and pivotably supporting the proximal end region of a rib by means of a pivot, such that each pivot is arranged outside the outer periphery of the central frame element.

According to a second aspect there is provided a collapsible photographic light reflector comprising an expanse of flexible material and a collapsible frame, the material having a rear surface, a reflective front surface and an outer peripheral edge; the frame including a plurality of ribs, each rib having a proximal end region and a distal end region, a central frame element having an outer periphery and supporting the proximal end regions of the ribs, and attachment means for connecting the frame to a light body carrying a light source; the ribs being pivotably supported by the central frame element so as to be adjustable between a deployed position and a folded position, the distal end regions of the ribs engaging the material in the region of its outer peripheral edge such that in the deployed position the outer peripheral edge of the material defines a light emitting opening, the reflector including locking means for locking the ribs in the deployed position; characterised in that each rib comprises two or more elongate rib elements and connection means connecting the rib elements such that the rib elements of each rib may be adjusted between a folded position and the deployed position, and in that means are provided for locking the rib elements of each rib in the deployed position.

According to a third aspect of the invention there is provided a collapsible photographic light reflector comprising an expanse of flexible material and a collapsible frame, the material having a rear surface, a reflective front surface and an outer peripheral edge; the frame including a plurality of ribs, each rib having a proximal end region and a distal end region, a central frame element for supporting the ribs, and attachment means for connecting the frame to a light body carrying a light source, the ribs being manipulable by the user to a deployed position in which they are supported at their proximal end regions by the central frame element, the distal end regions of the ribs engaging the material in the region of its outer peripheral edge such that in the deployed position the outer peripheral edge of the material dehmes a light emitting opening; characterised in that the ribs are locked in the deployed position by the engagement of their proximal end regions directly or indirectly with the central frame element, and in that the attachment means is supported in spaced relationship from the central frame element in front of the front surface by at least one elongate support element extending from the central frame element.

According to a fourth aspect there is provided a collapsible photographic light reflector comprising an expanse of flexible material and a collapsible frame, the material having a rear surface, a reflective front surface and an outer peripheral edge; the frame including a plurality of ribs, each rib having a proximal end region and a distal end region, and a central frame element having an opening for accommodating a rear mounted light source and first attachment means for detachably connecting the frame to a light body mounted behind the rear surface and carrying the rear mounted light source; the ribs being manipulable by the user to a deployed position in which they are supported at their proximal end regions by the central frame element, the distal end regions of the ribs engaging the r material in the region of its outer peripheral edge such that in the deployed position the outer peripheral edge of the material defines a light emitting opening; characterised in that the frame includes second attachment means for detachably connecting the frame to a light body carrying a front mounted light source, such that the second attachment means supports the front mounted light source in spaced relationship from the central frame element in front of the front surface.

According to a fifth aspect there is provided a collapsible photographic light reflector comprising an expanse of flexible material and a collapsible frame, the material having a rear surface, a reflective front surface and an outer peripheral edge; the frame including a plurality of ribs, each rib having a proximal end region and a distal end region, a central frame element for supporting the ribs, and attachment means for connecting the frame to a light body carrying a light source, the ribs being manipulable by the user to a deployed position in which they are supported at their proximal end regions by the central frame element, the distal end regions of the ribs engaging the material in the region of its outer peripheral edge such that in the deployed position the outer peripheral edge of the material defines a light emitting opening; the attachment means including a connection element which is engageable in use with the light body carrying the light source, and further including a seat together with retention means for connecting the connection element to the seat so as to permit rotational movement therebetween; characterised in that the retention means comprises a plurality of resiliently biased retention elements and the connection element is retained by friction between the retention elements and the seat.

According to a sixth aspect there is provided a lock ring for attaching a collapsible photographic light reflector to a light body carrying a light source, the lock ring being mounted on the light body so as to partially surround the light source; the reflector comprising an expanse of flexible material and a collapsible frame, the frame including a connection element, the lock ring releasably engaging the connection element; characterised in that the lock ring is formed from a material having a thermal S conductivity of at least 80 W/m-K.

An illustrative embodiment, which is not intended to limit the scope of the invention, will now be described by way of example and with reference to the accompanying drawings, in which: Fig. 1A is a front view of the central part of a softbox according to the prior art, in a partially deployed condition; Fig. 1B is a side view of the prior art softbox of Fig. 1A in a folded condition; Fig. 2A is a front view of a softbox according to a first embodiment, showing the softbox connected to a light body in a deployed condition; Fig. 2B is a side view of the softbox of Fig. 2A, with the light body removed; Fig. 3 is an enlarged view of the central portion of the softbox of Fig. 2A, in a partially deployed condition; Fig. 4 shows the light body of Fig. 2A; Fig. 5A is a rear view of the central frame element of Fig. 2A; Fig. 5B is a side view of the central frame element of Fig. SA, showing a connection element ready for connection thereto; Fig. 6 is a front view of a rear support element for connection to the central frame element of Fig. 5A; Figs. 7A and 7B are respectively enlarged front and side views of the pivot assemblies of Fig. 3, shown in the deployed condition; Figs. 7C and 7D are views corresponding respectively to those of Figs. 7A and 7B, showing the pivot assemblies in the folded condition; Fig. 7E shows a radial extension piece, catch and spring of one of the pivot assemblies; Fig. 8 is a side view of the rear support element of Fig. 6, showing a second attachment means attached thereto; and Fig. 9 shows a locking pivot assembly according to an alternative embodiment.

Referring to Figs. 2A and 2B, a collapsible photographic light reflector, hereinafter referred to as a softbox or lighting umbrella, comprises an expanse of flexible material 1 supported by a collapsible frame. The material preferably comprises a heat resistant woven fabric or the like, which may be made for example from carbon fibre or glass fibre, and is provided with a reflective front surface 3 which in use reflects the light emitted from the light source. In the example shown, the light source comprises a flash bulb or tube 4 in combination with an incandescent bulb 5, both supported by a light body 6. In the views shown the light body is hidden behind the material 1, but the inner part of its lock ring 7 can just be seen where it extends inside the connection element 8, which is attached to a seat formed on the rear face of the central frame element 10, to partially surround the light source.

It is found that by selecting a heat resistant material 1 such as glass fibre or carbon fibre the durability of the umbrella is improved and the deterioration which is commonly observed in the reflective surface of umbrellas formed from nylon fabric or the like may be avoided. This is believed to be due in part to the resistance of the fabric to thermal degradation, and partly to its resistance to abrasion by the ribs 11 and other elements of the frame. For umbrellas two metros or more in diameter, the weight of the fabric is desirably 250 grams per square metre or less, ensuring adequate foldability and portability; smaller umbrellas may employ heavier fabric, desirably less than 350 grams per square metro.

In order to further enhance the durability, and hence the long term effectiveness, of the umbrella and its reflective front surface 3, it is particularly preferred to form the reflective surface 3 by applying, preferably by spraying, a layer of liquid metal, such as aluminium or stainless steel, onto the heat resistant cloth. This helps to overcome the problem of delamination which is observed in umbrellas according to the prior art, which are often formed from a thin reflective layer applied by means of adhesive which tends to break and peel away from the base fabric as the umbrella is subjected to abrasion and to the heat from the light source.

Preferably the rear surface 9 of the material 1 is black so as to minimise unwanted reflected light.

The outer peripheral edge 12 of the material, which may be reinforced, defines a large light emitting opening 13. If required, a diffuser such as a translucent screen or cloth for controlling the quality of the emitted light, or a so-called "honeycomb" or "egg-crate" structure defining many small open ended cells and serving to direct the light, may be arranged to cover the opening 13. Suitable attachment means for such accessories may be provided if required at the outer peripheral edge 12 of the material.

The central frame element 10 is formed as an aluminium ring, although other shapes and materials are of course possible, and supports eight ribs 11, which may comprise flexible rods, tubes or other elongate sections of carbon fibre, aluminium, steel or other suitable material, in spaced apart relationship. Each rib is supported at its inner or proximal end 15 by a pivot assembly 2 which enables the umbrella to be folded up for transport and storage, and at its outer or distal end 16 engages the material in the region of its outer peripheral edge 12. A reinforced pocket 17 or the like may be provided for this purpose. The central frame element thus maintains the ribs in the deployed position shown, and the resilience of the ribs keeps the material 1 in the stretched condition necessary to achieve good light reflection.

Although the example shown is octagonal in shape and has eight ribs, it is of course possible to form the umbrella in a rectilinear or other shape, or to use a different number of ribs. A large umbrella may be 2m or more in diameter or length, and in order to reduce the folded length of the umbrella during transport and storage, each rib 11 may be provided with one or more hinges 18 or other connection means which join together two or more rib elements 19, 20 so that the ribs and the material 1 can be folded not only at the central frame element 10 but also at an intermediate point 18, making it easier to transport larger sizes of umbrella.

in the example shown the umbrella may be folded along the dotted line 21; where the ribs are arranged on the front surface of the umbrella as shown, they preferably fold outwards towards the back of the umbrella, as this has the additional advantage of relieving the stress in the material 1 when the hinges 18 are folded back. Although single hinges are shown, double hinges may alternatively be used, with a short connecting piece in between them, or even elastic couplings or the like. In each case means are provided for locking the hinges or other connection means in the deployed position; the locking means may form part of the frame or part of the material.

The locking means may also be formed by a projection or the like on one of the rib elements which engages the other rib element to prevent it from folding inwards; the tension in the material 1, particularly from the peripheral edge 12, may then be used to lock the rib elements 19, 20 in their deployed position, forming a sort of bistable mechanism. The ribs may then be folded back by applying pressure against the tension of the material to force them back until they are straight, at which point the tension in the material 1 continues the backward movement so that the ribs fold at their hinge point and the material relaxes. The outer peripheral edge 12 of the material, or an intermediate region of the material or the frame, may be Masticated or sprung to assist this procedure.

By folding the ribs in such a way as to relieve the stress in the stretched material, the relaxed material 1 is less likely to be damaged by abrasion or by the distal ends 16 of the ribs forcing their way through the pockets 16 under pressure against the stretched material. This makes it possible to fix the ribs 11 permanently to the central frame element 10, which is to say, in such manner as to permit disassembly for maintenance or replacement but not routine detachment for transport or storage, without incurring the disadvantage that the material and the ribs are constantly stretched, leading to abrasion and damage or even to looseness of the umbrella when it is deployed.

It is of course possible to provide sockets into which the ribs may be inserted, the sockets either being hinged to the central frame element or formed directly in the central frame element; where they are formed directly in the central frame element, the umbrella may be deployed by merely manipulating the proximal and distal ends of each rib so that they are forced respectively into the sockets in the central frame element and into the pockets at the edge of the material. The ribs may then be removed and carried as a bundle. However, in practice different sizes and types of softbox may be used together in a busy studio or on location, and bundles of loose ribs of similar but slightly different lengths are easily mixed up or mislaid, leading to sagging of the umbrellas and ineffective reflection. By retaining the ribs to the central frame element this problem is avoided.

Referring to Figs. 1A and 1B a prior art lighting umbrella is shown by way of comparison in both the deployed and folded conditions. The ribs 111 are hinged to a central frame element 110 by means of pivoting connectors 100, and it is seen that when the connectors 100 are moved to their folded condition, as shown in Fig. I B. the material 101 of the umbrella is stretched more tightly around the margin of the central frame element 1 10 and the ribs 11 1 are additionally stressed, leading to abrasion of the material and particularly to additional pressure at the ends of the ribs, which in time may result in the distal ends of the ribs forcing their way through the outer margin of the material. For this reason it is often preferable where the material remains under additional tension when the umbrella is folded to remove the ribs 111 altogether and carry them as a separate bundle.

Referring now to Figs. 3 and 7A - 7E, the central portion of the umbrella of the present embodiment is shown in more detail with part of the material I cut away for clarity. Each pivot assembly 2 includes a radial extension piece 30 which is held in a socket 31 formed on the outer periphery 32 of the central frame element 10, and retained by means of a holding screw 33 which engages in a corresponding recess 42. Mounting holes 50 are also formed in the front face of the central frame element 10 which may be used for supporting a light body attachment means, as further described hereinafter.

Each radial extension piece 30 carries a pivot pin 34 which retains a socket 35 so that the socket can pivot through an angle of approximately 90 between the deployed (Figs. 7A, 7B) and the folded (Figs. 7C, 7D) positions. The proximal end 15 of each rib is held in a socket 35.

Each radial extension piece 30 is arranged to carry the pivot 34 outside the outer periphery 32 of the central frame element, which ensures that when the pivot assemblies are folded the material l is not placed under additional tension against the resilience of the ribs by forcing it to fold around the outer periphery 32 of the central frame element. Since this minimises the stress on ribs and material when the umbrella is folded the ribs may advantageously be fixed into the sockets 35 so that they cannot be detached, at least in normal use. Steel ribs for example may be brazed or welded into the sockets, and carbon fibre ribs may be glued.

Alternatively the ribs may be detachable. In an alternative embodiment, recesses may be formed in the outer periphery of the central frame element to accommodate up to half of the diameter of each socket 35 in the folded condition, the sockets 31 then being formed in the recesses.

Each pivot assembly is provided with locking means which engage automatically when the rib is folded out to lock it in its deployed position; this makes it easy to deploy the umbrella. The locking means are conveniently formed by catches 36 which are retained inside the sockets 35 and biased by springs 37 or the like to the locked position. Each catch is retained by a pivot 38 in a housing in the socket 35 and in the locked position abuts an abutment face 39 which is formed on the radial extension piece so that it is transverse to the proximal end of the rib in the deployed position, best shown in Fig. 7E. The catch is released by pushing its protruding part in the direction of the arrow R to bring it out of abutment with the abutment face, allowing the assembly 2 to fold. In the folded condition a sloping face 40 of the catch remains in sliding contact with a rounded corner 41 of the radial extension piece, allowing the catch to slip into the locked position (Figs.

7A, 7B, 7E) when the rib is fully deployed.

In alternative embodiments the ribs may directly engage the radial extension pieces without sockets, and other locking means may of course be employed, which may form part of the frame, such as axially sliding sleeves coaxial with the ribs, or may form part of the material 1. By locking the ribs by engaging them as described either directly or indirectly with the central frame element 10 the advantage is realised that no internal additional struts are required for supporting the ribs, and the attendant disadvantage of shadows or "ghost images" produced by such internal struts is avoided. Referring to Fig. 9, in one alternative embodiment each rib 11' is axially

mobile in a direction (shown by arrow R) radially outward from the outer periphery of the central frame element, so as to enable it to be disengaged from a socket, stud or the like which is fixed in position relative to the central frame element and locks the rib in the deployed position when the rib engages it. For example, a slot 90 may be formed in the proximal end region of the rib l 1' or in the socket, with a pin 91 passing through the slot to retain the rib or socket to the radial extension piece 30'. The resilience of the rib 1 1' and the tension in the material may then force the rib 1 1' towards the central frame element 10 so that the pin 91 moves towards the outward end 92 of the slot, in which position the rib 1 1' or the socket engage fixed locking means on the central frame element. In the example shown the extreme proximal end 93 of the rib 11' engages in a socket 94 in the radial extension piece 30'. By pulling the rib radially outwards away from the central frame element until the pin abuts the inward end of the slot 90, the rib may be released from the fixed locking means 94 to enable it to pivot around the pin into the folded condition. Again, recesses may be formed in the outer periphery of the central frame element to accommodate up to half of the diameter of each rib in the folded condition.

Returning to the present embodiment and referring to Figs. 5A and 5B, Fig. 5A shows the rear face of the central frame element 10, which in use faces away from the front surface 3 of the umbrella and which is provided with a shallow, recessed seat 51 which receives the round mounting flange 52 of the connection element 8.

The seat surrounds the central opening 58 which accommodates the light source mounted on the rear mounted light body 6. The connection element is formed as a sleeve with "bayonet" type cranked slots as shown on either side at one end and the mounting flange 52 at the other end, and serves in use to connect the umbrella to the light body, when it extends towards the light body and partially surrounds the light source.

Other forms of connection element are of course feasible, including patterns which do not surround the light source, but generally annular or sleeve type patterns, such as the one illustrated, are the most common. For example, instead of the bayonet slots shown, an alternative pattern of connection element provides two projecting lugs which engage in corresponding slots on the light body.

Another popular pattern employs a rubber sleeve in place of the slotted sleeve illustrated, with a sprung band to clamp it to the light body; still further alternative patterns employ a flexible steel band which is attached in place of the illustrated sleeve around part of the inner margin of the mounting flange; the band is clamped around the light body by means of a lever type clip.

Since it may be required to attach the umbrella to many different types of light body, it is desirable that the connection element should be quickly and easily detachable and interchangeable with other connection elements, including for example the alternative patterns described above, which conform to other light bodies. It is also desirable that the connection element should rotate relative to the rest of the frame, so that any unevenness of light distribution may be optimally positioned with respect to the photographic subject. It is found in practice that threaded screws alone are not effective for this purpose since, while they may be provided with sufficiently fine threads to adjust the friction between the flange and the seat, they then take too long to unscrew in order to detach the seat altogether.

A set of resiliently biased retention elements is therefore provided, each comprising a rotating catch 54 with projecting wings 55 which is resiliently biased by a spring 56 towards the flange 52 positioned on the seat 51. The spring and catch are retained to the central frame element by a screw or stud 57, and together with the connection element 8 form attachment means for connecting the umbrella to the light body. The catches are shown in the released position; by turning the catch through 90 the edge of the catch may be brought over the edge of the flange 52 so as to clamp it to the seat, forming a frictional sliding clutch. The clutch pressure may be adjusted by means of the screw or stud 57, and means (for example, projections and corresponding recesses) may be provided for locking the catch 54 in position against unwanted movement. Suitable plastics material of adequate heat resistancy may be incorporated into the seat if required. The retention elements may of course take other forms, such as a single adjustable element, and may if required merely control the rotation of a permanently l O mounted connection element; preferably however they should also permit it to be easily and quickly detached.

It is surprisingly found in practice that by machining the central frame element l O from a solid block or tube of aluminium or aluminium alloy, it may be made substantially more robust and resistant to fracturing and deformation than when it is cast in aluminium or aluminium alloy, and it is therefore preferred to use a machined ring. By providing radial extension pieces 30 as described above, it is also possible to dispense with the radial slots commonly found in the corresponding frame elements of the prior art; this both further strengthens the ring and enables it to be machined at acceptable cost, since the complex operation of slot forming is no longer required. The machined ring of the present embodiment may thus be more monolithic and stronger than the typical cast ring

of the prior art.

Referring to Figs. 6 and 8, a rear support element 60 is provided, comprising a flat plate with a mounting bracket 61 for attachment to a stand or the like. The plate is adapted to fit the seat 51 of the central frame element in place of the connection element 8, enabling the umbrella to be rotatably mounted on a stand by means of the bracket 61 which then protrudes from the rear of the umbrella in the same position as the connection element 8 in Fig. 2B.

A second attachment means 80 is provided for detachably front mounting a light body in front of the front surface 3 of the umbrella so that the light source faces the front of the umbrella in spaced relationship from the central frame element; the umbrella may thus be mounted on a stand by means of the plate 60 and the light body installed through the light emitting opening 13.

The second attachment means is conveniently formed as an aluminium ring 81 with a seat 82 and retention elements 83 identical to those of the central frame element 10; peripheral sockets for mounting ribs are of course not required. The ring 81 is supported instead in spaced relationship from the central frame element by elongate support elements 84, 85, which are conveniently formed as cranked rods. Four support elements are shown, but it is possible to use more or fewer than this, or even a single element. The central opening 86 and seat 82 of the ring 81 are advantageously of the same diameter as the opening 58 and seat 51 1 S of the central frame element 10, enabling the connection element 8 to be fitted to the second attachment means 80 instead of to the central frame element 10. The user may thus choose whether to use the umbrella with a rear mounted light source or a front mounted light source.

In the example shown, the second attachment means is supported by the rear support element 60 by engaging the support rods 84 with holes 87 and the support rod 85 with the slot 88. Desirably the support elements 84, 85 are rotatable in the holes 87 and slot 88, enabling their cranked sections to be rotated inwards so that the rods can pass through the central opening 58 from the rear, then rotated outwards for engagement with the ring 81. Alternatively the rods may be inserted through the opening 58 from the front and then engaged with the plate 60. In alternative embodiments the second attachment means 80 may be formed with a smaller overall diameter than the opening 58, or in several parts for quick connection after insertion through the opening.

The support rod 85 is hollow and carries a cable 89 with connectors 95; this allows a front mounted light body to be connected to a power supply located behind the umbrella, without the cable trailing out through the light emitting opening 13 and causing a shadow. This is preferable to passing the cable through a slit in the material, as is commonly done with front mounting light bodies in large umbrellas according to the prior art, since tearing of the material often then results. Equivalent alternative electrical conductor means might of course be provided.

Alternatively the second attachment means 80 may be supported directly by the central frame element 10, for example by engaging the rods 84, 85 with the mounting holes 50. The rods may be rotated so that their cranked sections provide adjustment for the difference in the spacing of holes 50 and holes and slot 87, 88.

In alternative embodiments, one or more straight or curved rods or other support elements might be used to support the second attachment means in front of the central frame element 10. The central frame element 10 need not be formed as an annular element with a central opening, but (where a rear mounted light source is not required) might be for example a blank plate with a rear bracket similar to the plate 60.

Referring to Fig. 4, the light body 6 includes a power socket 98 or alternatively a power cable, as well as a bracket 99 for attachment of the body 6 and attached umbrella to a stand or the like, and is provided with a rotatable lock ring 7 which partially surrounds the light source 4, 5. The lock ring includes an annular groove 96 which in use receives the sleeve of the connection element 8 so that the lock ring extends partially inside the connection element towards the front of the umbrella. The connection element 8 is conventionally held in place by rotating the lock ring so as to engage two lugs within the groove 96 with the bayonet slots of the connection element; other patterns are of course feasible.

Light bodies are commonly provided with lock rings made from plastics material, and it is found in practice that this can melt in the heat from the light source. It is preferred therefore to form the lock ring 7 from a heat resistant material, and preferably from a heat resistant material having a thermal conductivity of at least 80 W/m-K, more preferably of at least 140 W/m-K, and still more preferably of over 190 W/m-K, even as high as 230 or 240 W/m-K or more, as it is found that the lock ring may then form an effective heatsink for the light source, carrying heat away from the flexible fabric forming the canopy of the umbrella and thus extending its life. Desirably the lock ring may be formed from aluminium or an aluminium alloy selected for a suitable combination of strength and workability and a thermal conductivity suitable inter alla for the power of the light source, the diameter of the ring and the thermal resistance of the umbrella fabric.

When the lock ring is formed from highly thermally conductive material it may become too hot to grasp, and it is therefore preferred to provide one or more releasable clamp means such as spring loaded quick release pins 97, or alternatively screws or the like, which extend outwardly from the lock ring; the user may then clamp the lock ring to the frame of the umbrella without grasping the hot lock ring to twist it in the conventional way. The connection element may then be formed if required without bayonet slots or the like.

In summary, embodiments of the invention provide a collapsible photographic lighting reflector comprising a collapsible frame which supports an expanse of reflective, flexible material. The frame may include hinged two-piece ribs which are retained to a machined aluminium ring by pivots which are carried outside the outer circumference of the ring, allowing the umbrella to be folded compactly for transportation without placing additional stress on the attached ribs. A central aperture in the ring may accommodate a connection element which is engageable with a thermally conductive aluminium lock ring for attachment of a rear mounted light source; a flat mounting plate with a rear bracket may be substituted for the connection element or the ring, and a front mounted light source carried instead on elongate rods extending from the mounting plate or from the front of the ring.

The connection element or mounting plate may be quickly assembled to the ring by means of spring loaded catches to form a rotating clutch. The absence of internal struts for supporting the ribs helps to avoid the formation of shadows.

The present invention in all of its aspects thus provides a lighting umbrella which is robust, convenient and effective in use. While the described embodiments are presented for illustration, it is to be understood that the scope of the invention is limited only by the claims.

Claims

1. A collapsible photographic light reflector comprising an expanse of flexible material and a collapsible frame, the material having a rear surface, a reflective front surface and an outer peripheral edge; the frame including a plurality of ribs, each rib having a proximal end region and a distal end region, a central frame element having an outer periphery and supporting the proximal end regions of the ribs, and attachment means for connecting the frame to a light body carrying a light source; the ribs being pivotably supported by the central frame element so as to be adjustable between a deployed position and a folded position, the distal end regions of the ribs engaging the material in the region of its outer peripheral edge such that in the deployed position the outer peripheral edge of the material defines a light emitting opening, the reflector including locking means for locking the ribs in the deployed position; characterised in that the frame includes a plurality of radial extension pieces, each radial extension piece being supported by the central frame element and pivotably supporting the proximal end region of a rib by means of a pivot, such that each pivot is arranged outside the outer periphery of the central frame element.

2. A reflector according to claim 1, characterised in that the ribs are retained by the pivots such that the ribs are not detachable from the central frame element during normal use.

3. A reflector according to claim l or claim 2, characterised in that the locking means engages automatically when each rib is moved to the deployed position.

4. A reflector according to any of claims 1, 2 or 3, characterised in that the locking means of each rib includes a catch which abuts an abutment face in the deployed position.

5. A reflector according to any of claims l, 2 or 3, characterized in that each rib is mounted for axial movement in a radial direction away from the outer periphery of the central frame element so as to disengage the locking means.

6. A collapsible photographic light reflector comprising an expanse of flexible material and a collapsible frame, the material having a rear surface, a reflective front surface and an outer peripheral edge; the frame including a plurality of ribs, each rib having a proximal end region and a distal end region, a central frame element having an outer periphery and supporting the proximal end regions of the ribs, and attachment means for connecting the frame to a light body carrying a light source; the ribs being pivotably supported by the central frame element so as to be adjustable between a deployed position and a folded position, the distal end regions of the ribs engaging the material in the region of its outer peripheral edge such that in the deployed position the outer peripheral edge of the material defines a light emitting opening, the reflector including locking means for locking the ribs in the deployed position; characterized in that each rib comprises two or more elongate rib elements and connection means connecting the rib elements such that the rib elements of each rib may be adjusted between a folded position and the deployed position, and in that means are provided for locking the rib elements of each rib in the deployed position.

7. A reflector according to claim 6, characterised in that the ribs are retained to the central frame element such that the ribs are not detachable therefrom during normal use.

8. A collapsible photographic light reflector comprising an expanse of flexible material and a collapsible frame, the material having a rear surface, a reflective front surface and an outer peripheral edge; the frame including a plurality of ribs, each rib having a proximal end region and a distal end region, a central frame element for supporting the ribs, and attachment means for connecting the frame to a light body carrying a light source, the ribs being manipulable by the user to a deployed position in which they are supported at their proximal end regions by the central frame element, the distal end regions of the ribs engaging the material in the region of its outer peripheral edge such that in the deployed position the outer peripheral edge of the material defines a light emitting opening; characterised in that the ribs are locked in the deployed position by the engagement of their proximal end regions directly or indirectly with the central frame element, and in that the attachment means is supported in spaced relationship from the central frame element in front of the front surface by at least one elongate support element extending from the central frame element.

9. A collapsible photographic light reflector comprising an expanse of flexible material and a collapsible frame, the material having a rear surface, a reflective front surface and an outer peripheral edge; the frame including a plurality of ribs, each rib having a proximal end region and a distal end region, and a central frame element having an opening for accommodating a rear mounted light source and first attachment means for detachably connecting the frame to a light body mounted behind the rear surface and carrying the rear mounted light S source; the ribs being manipulable by the user to a deployed position in which they are supported at their proximal end regions by the central frame element, lO the distal end regions of the ribs engaging the material in the region of its outer peripheral edge such that in the deployed position the outer peripheral edge of the material defines a light emitting opening; characterised in that the frame includes second attachment means for detachably connecting the frame to a light body carrying a front mounted light source, such that the second attachment means supports the front mounted light source in spaced relationship from the central frame element in front of the front surface.

10. A reflector according to claim 9, characterized in that there is provided a rear support element adapted to engage a supporting stand or the like, and the rear support element may be detachably connected to the first attachment means in place of the light body carrying the rear mounted light source.

11. A reflector according to claim 10, characterized in that the second attachment means is supported by the rear support element.

12. A reflector according to claim 9 or claim 10, characterized in that the second attachment means is detachably connected to the central frame element.

13. A reflector according to claim 10 or claim 11, characterised in that the first attachment means comprises a connection element which in use is engageable with the light body carrying the rear mounted light source, together with retention means for detachably connecting the connection element to the central frame element around the opening thereof, and the rear support element comprises a plate which may be detachably connected to the central frame element in place of the connection element.

14. A reflector according to any of claims 9 - 13, characterised in that the second attachment means includes electrical conductor means for carrying a power supply from behind the rear surface to the light body carrying the front mounted light source.

15. A collapsible photographic light reflector comprising an expanse of flexible material and a collapsible frame, the material having a rear surface, a reflective front surface and an outer peripheral edge; the frame including a plurality of ribs, each rib having a proximal end region and a distal end region, a central frame element for supporting the ribs, and attachment means for connecting the frame to a light body carrying a light source, the ribs being manipulable by the user to a deployed position in which they are supported at their proximal end regions by the central frame element, the distal end regions of the ribs engaging the material in the region of its outer peripheral edge such that in the deployed position the outer peripheral edge of the material defines a light emitting opening; s the attachment means including a connection element which is engageable in use with the light body carrying the light source, and further including a seat together with retention means for connecting the connection element to the seat so as to permit rotational movement therebetween; characterised in that the retention means comprises a plurality of resiliently biased retention elements and the connection element is retained by friction between the retention elements and the seat.

16. A reflector according to claim 15, characterised in that the retention elements comprise releasable catches which may be manipulated from an engaged position to a disengaged position so as to enable the connection element to be detached from the seat.

17. A lock ring for attaching a collapsible photographic light reflector to a light body carrying a light source, the lock ring being mounted on the light body so as to partially surround the light source; the reflector comprising an expanse of flexible material and a collapsible frame, the frame including a connection element, the lock ring releasably engaging the connection element; characterised in that the lock ring is formed from a material having a thermal conductivity of at least 80 W/m-K.

18. A lock ring according to claim 17, characterised in that the lock ring is formed from a material having a thermal conductivity of over 190 W/m-K.

19. A collapsible photographic light reflector substantially as described with reference to the accompanying description and drawings.

19. A lock ring according to claim 17 or claim 18, characterized in that the lock ring is provided with at least one releasable clamp means extending outwardly therefrom, the clamp means being operable by a user to clamp the lock ring to the connection 1 5 element.

20. A reflector according to any preceding claim, characterized in that the flexible material comprises a heat resistant fabric and the reflective front surface comprises a metallic layer which is applied to the fabric in a liquid state.

21. A reflector according to any preceding claim, characterized in that the central frame element comprises a substantially annular element formed by machining from a block or tube of aluminium or aluminium alloy.

22. A collapsible photographic light reflector substantially as described with reference to the accompanying description and drawings. To

Amendments to the claims have been filed as follows the distal end regions of the ribs engaging the material in the region of its outer peripheral edge such that in the deployed position the outer peripheral edge of the material defines a light emitting opening; the attachment means including a connection element which is engageable in use with the light body carrying the light source, and further including a seat together with retention means for connecting the connection element to the seat so as to permit rotational movement therebetween; characterised in that the retention means comprises a plurality of resiliently biased retention elements and the connection element is retained by friction between the retention elements and the seat.

17. A reflector according to any preceding claim, characterized in that the flexible material comprises a heat resistant fabric and the reflective front surface comprises a metallic layer which is applied to the fabric in a liquid state.

18. A reflector according to any preceding claim, characterized in that the central frame element comprises a substantially annular element formed by machining from a block or tube of aluminium or aluminium alloy.