WO2007015101A2

WO2007015101A2 - Inspection tool

Info

Publication number: WO2007015101A2
Application number: PCT/GB2006/002905
Authority: WO
Inventors: Robert James Harrison; Peter David Martin Townsend
Original assignee: Super Rod Limited
Priority date: 2005-08-03
Filing date: 2006-08-03
Publication date: 2007-02-08
Also published as: GB0515993D0; WO2007015101A3

Abstract

An inspection tool suitable for use in inspecting concealed places in a building comprises a series of flexible rods (4) detachably connectible together end to end, a camera assembly (1) detachably connectible to one end of the series of rods and a display unit (2) including a receiver for receiving a wireless transmission from the camera assembly (1) and a display (3) for displaying a picture generated from the wireless transmission. The camera assembly (1) has, in a direction transverse to the longitudinal axis of the rods in the region of the connection to the camera when in use the rods (4) are connected together and to the camera, a maximum dimension less than 50 mm. The camera assembly (1) includes a camera (18), a light source (18A) for illuminating a region in the field of view of the camera, a battery and an electric circuit for generating a wireless transmission from the signal received from the camera.

Description

INSPECTION TOOL

This invention relates to an inspection tool suitable for use in inspecting concealed spaces in a building. Some purpose built inspection tools already exist. For example, it is known to inspect drains by attaching a camera to the end of a series of drain rods and passing a picture signal- generated by the camera back along a cable that may run alongside or inside the rods to a display of some kind.

According to a first aspect of the invention there is provided an inspection tool suitable for use in inspecting concealed places in a building, the tool comprising: a series of flexible rods detachably connectible together end to end, a camera assembly detachably connectible to one end of the series of rods and having, in a direction transverse to the longitudinal axis of the rods in the region of the connection to the camera when in use the rods are connected together and to the camera, a maximum dimension less than 50 mm, the camera assembly including a camera, a light source for illuminating a region in the field of view of the camera, a battery and an electric circuit for generating a wireless transmission from a signal received from the camera, and a display unit including a receiver for receiving the wireless transmission from the camera assembly and a display for displaying a picture generated from the wireless transmission. By providing a camera of relatively small size with its own light source and arranging for wireless transmission of the picture signal to a remote display unit, a tool which can serve a wide variety of purposes can be provided. Such a tool may, for example, be used to inspect wiring in ducting, to inspect possible locations of termites or other pests or to inspect underfloor heating. By providing a series of flexible rods, the reach of the camera can be adjusted according to need. The tool can also be used in applications outside buildings, for example in road traffic accidents.

By ensuring that the maximum dimension of the camera assembly in the transverse direction referred to above is less than 50 mm (and more preferably 30 mm or less) , a tool which is able to pass through small spaces can be provided. Typically the transverse dimension referred to above will be greater than 8 mm. It is desirable for the camera assembly not to be too small in order that adequate battery energy for operating the camera can be stored and in order to avoid undue cost.

The camera assembly may comprise a housing in which the camera unit, battery and electric circuit are received. The light source, which may comprise a plurality of light emitting diodes, may be mounted in or on the housing. Surprisingly we have found that as few as two light emitting diodes may be sufficient. The light source may be mounted in or on the housing behind the camera. The tool preferably further includes light emitting means on the camera assembly, or on the rods in the region of the camera assembly, for providing a visual indication of the position of the camera. Often the camera will be placed in a dimly lit or unlit location and the provision of such light emitting means helps a user of the tool to know the location of the camera. The light emitting means may be provided on the camera assembly itself but preferably comprises at least a portion of one of the rods, which portion is arranged to glow in the dark. That portion may be fluorescent or luminescent.

Preferably at least some of the rods, and more preferably all of the rods, are detachably connectible by screw connections. Screw connections can provide secure but detachable connections in a relatively simple and economical manner.

Preferably, at least some, and more preferably all, of the rods are of substantially circular cross-section and have a diameter in the range of 3 to 15 mm and more preferably 5 to 15 mm. Rods of such diameter can readily be made flexible enough to be passed round fairly tight corners whilst still being stiff enough to support and guide the camera assembly. Preferably, at least some, and more preferably all, of the rods are flexible and are able to be flexed repeatedly to a radius of curvature of less than 500 mm, without damage. More preferably at least some of the rods are more flexible and are able to be flexed repeatedly to a radius of curvature of less than 50 mm, without damage. Flexible rods can be made elastically deformable with the result that they tend to return to their previous shape, which is preferably straight, as soon as any external force is removed, or the rods can be made plastically deformable with the result that they tend to stay in any new shape into which they are put. Preferably, at least some of the flexible rods are elastically deformable/ preferably the flexural modulus of those rods is greater than 20. It may also be advantageous for at least one rod to be plastically deformable; said at least one plastically deformable rod is preferably connectible between the camera and the other rods. In that case the plastically deformable rod can be adjusted to a desired predetermined shape by a user before guiding the camera to its desired location and can remain in that shape.

The length of the rods can be chosen according to the application required. Typically at least some of the rods have a length in the range of 0.5 to 5 m and more preferably in the range of 0.5 to 1.5 m. The total length of the series of rods is typically in the range of 4 to 15 m, but may be longer or shorter. There are usually three or more rods .

The camera assembly is preferably connectible to the series of rods by a detachable fastening. It may be important that the risk of the camera becoming detached from the rods during an inspection is low, since the camera might be lost in certain applications if it did become detached. Preferably, additional locking means are provided for ensuring the security of the fastening of the camera assembly to the rods, which fastening may be direct or indirect. The additional locking means may take a variety of forms: in one embodiment of the invention where fastening of the camera assembly to the rods is by means of a screw fastening, the additional locking means is a locking nut.

The camera assembly is preferably of generally cylindrical shape, the longitudinal axis of the cylinder being aligned with the longitudinal axis of the rods in the region of the camera when in use the rods are connected together and to the camera. An arrangement of this kind facilitates guiding of the camera assembly to its desired location. Preferably, the longitudinal axis of the cylinder is coincident with the longitudinal axis of the rods in the region of the camera when in use the rods are connected together and to the camera. The space occupied by the camera is preferably less than 250 cm³ The camera assembly may include a waterproof housing in which the camera is located. The light source, the battery and the electric circuit are each preferably also located in the waterproof housing.

The camera assembly preferably includes a front end cap in which the camera is received. At least a portion of the front end cap may be translucent and may be transparent but is not necessarily transparent. A focusing facility may be provided, for example, by adjusting the position of the camera relative to the end cap. The adjustment may be a screw adjustment.

Preferably, the camera is able to detect radiation of a wavelength in the infra red region of the spectrum. That enables the camera to provide a useful picture even in dimly lit or unlit spaces. The camera is preferably able also to detect radiation of a wavelength in the visible part of the spectrum and therefore the picture displayed can be a colour picture. Preferably there is a substantial overlap between the wavelength of the radiation emitted by the light source and the wavelength of the radiation able to be detected by the camera.

It should be understood that where reference is made herein to "light", that is to be taken as referring to wavelengths of radiation both in the visible spectrum and on either side of the visible spectrum.

Preferably, the tool is arranged such that when the camera assembly is in use detachably connected to the rods, the assembly is freely rotatable relative to the rods about the longitudinal axis of the rods in the region of the camera. Preferably a freely rotatable member is mounted on the end of a flexible rod and the camera is connected to the freely rotatable member. Providing such free rotation can for example enable the camera to be maintained in a consistent orientation even if the rods are rotated. Also, it reduces the likelihood of the camera becoming unscrewed from the rods accidentally. In an embodiment of the invention described below, the camera assembly is connected to one end of a plastically deformable rod whose other end is rotatably connected via the freely rotatable member to a series of elastically deformable rods; that embodiment represents just one possible arrangement in accordance with the invention. The camera assembly preferably includes an aerial which may be an external aerial. An internal aerial may be located in the housing of the camera assembly or may comprise a part of the housing itself.

The battery is preferably a rechargeable battery. The camera assembly preferably further includes a switch for connecting and disconnecting the battery. Such arrangements facilitate the provision of a compact camera assembly that is able to sustain effective operation for a useful period of time, for example, one hour. The switch may be arranged for remote activation, for example by magnetic force, or for direct activation by physical contact, for example by rotating one part of the camera - Q -

assembly relative to another, for example, by rotating one part of the camera housing relative to another.

Whilst the present invention is designed to be used with a series of flexible rods, one potential advantage of the invention is that it may be applied to an existing series of rods as a retrofit kit. In this case the rods need not form part of the kit that is sold. Accordingly, in a second aspect, the invention provides an inspection tool suitable for use in inspecting concealed places in a building, the tool comprising: a camera assembly for detachable connection to one end of a series of rods and having, in a direction transverse to the longitudinal axis of the rods in the region of the connection to the camera when in use the rods are connected together and to the camera, a maximum dimension less than 50 mm, the camera assembly including a camera, a light source for illuminating a region in the field of view of the camera, a battery and an electric circuit for generating a wireless transmission from a signal received from the camera, and a display unit including a receiver for receiving the wireless transmission from the camera assembly and a display for displaying a picture generated from the wireless transmission. The tool preferably further includes light emitting means on the camera assembly for providing a visual indication of the position of the camera. The tool preferably further comprises a rod for connection at one end to the camera assembly and for connection at the other end to a series of rods, and the light emitting means preferably comprises at least a portion of the rod, which portion is arranged to glow in the dark.

The tool preferably further comprises a plastically deformable rod for connection at one end to the camera assembly and for connection at the other end to a series of rods. The plastically deformable rod may be provided as part of the kit even when other rods are not. The tool preferably further comprises a freely rotatable member for connection at one end to the camera assembly and for connection at the other end to a series of rods, for mounting the camera for free rotation relative to the rods .

For some applications of the invention it may be possible to provide a cable linking the camera assembly to the display, rather than providing a wireless link. Accordingly, in a third aspect of the invention there is provided an inspection tool suitable for use in inspecting concealed places in a building, the tool comprising: a series of flexible rods detachably connectible together end to end, at least some of the rods having a flexural modulus greater than 20, a camera assembly detachably connectible to one end of the series of rods, the camera assembly including a camera, a light source for illuminating a region in the field of view of the camera, and an electric circuit for transmitting a picture signal received from the camera to a remote location, and a display unit including a receiver for receiving the picture signal from the camera assembly and a display for displaying a picture generated from the signal.

Similarly, according to a fourth aspect of the invention, there is provided an inspection tool suitable for use in inspecting concealed places in a building, the tool comprising: a series of flexible rods detachably connectible together end to end, at least some of the rods being of substantially circular cross-section and having a diameter in the range of 5 to 15 mm, a camera assembly detachably connectible to one end of the series of rods and having, in a direction transverse to the longitudinal axis of the rods in the region of the connection to the camera when in use the rods are connected together and to the camera, a maximum dimension less than 50 mm, the camera assembly including a camera and an electric circuit for transmitting a picture signal received from the camera to a remote location, and a display unit including a receiver for receiving the picture signal from the camera assembly and a display for displaying a picture generated from the signal.

It may be seen from the description above that whilst a preferred form of the invention is in accordance with the first aspect of the invention, many modifications to that aspect of the invention may be made. In a broader aspect, the present invention provides an inspection tool suitable for use in inspecting concealed places in a building, the tool comprising: a camera assembly detachably connectible to one end of a series of rods, the camera assembly including a camera and an electric circuit for transmitting a picture signal received from the camera to a remote location, and a display unit including a receiver for receiving the picture signal from the camera assembly and a display for displaying a picture generated from the signal, wherein the tool includes one or more of the following features :

(a) the tool further includes a series of flexible rods detachably connectible together end to end,

(b) the tool further comprises light emitting means on the camera assembly for providing a visual indication of the position of the camera, and a rod for connection at one end to the camera assembly and for connection at the other end to a series of rods, the light emitting means comprising at least a portion of the rod, which portion is arranged to glow in the dark,

(c) the electric circuit of the camera assembly is for generating a wireless transmission from a signal received from the camera, and the display unit includes a receiver for receiving the wireless transmission from the camera assembly,

(d) the tool further comprises a plastically deformable rod for connection at one end to the camera assembly and for connection at the other end to a series of rods,

(e) the tool further comprises a freely rotatable member for connection at one end to the camera assembly and for connection at the other end to a series of rods, for mounting the camera for free rotation relative to the rods, and

(f) the camera assembly further includes a light source for illuminating a region in the field of view of the camera.

It should be understood that one of the features described above as essential or preferred in one particular aspect of the invention may also be used in another aspect where possible and/or appropriate, but in the interests of brevity all those different possible combinations have not been referred to above.

According to another aspect of the invention there is provided a method of inspecting a concealed place in a building, the method including the following steps: detachably connecting together a series of rods in end to end relationship, detachably connecting a camera assembly at one end of the series of flexible rods, the camera assembly including a camera and an electric circuit for transmitting a picture signal received from the camera to a remote location, inserting the camera into a confined space and manipulating the rods to move it through the confined space to a position within sight of the concealed place to be inspected, and transmitting a picture of the concealed place from the camera to a display unit at a location remote from the camera.

Preferably the camera is freely rotatable relative to the rods. The camera may be arranged to adopt a predetermined orientation on the end of the rods. For example, if the camera is freely rotatable it may be arranged to adopt an orientation in which it is viewing downwardly.

The transmission of the picture to the remote location is preferably a wireless transmission. The picture signal may be a colour picture signal or a black and white picture signal .

The method of the invention may be used, for example, for any of the following purposes: attic or ceiling inspection; roof surveys; termite or other pest location; inspection in cavity walls, under floors or over ceilings of electrical wiring or other electrical equipment; inspection of concealed spaces for security purposes; inspection of ducts; drain surveys; locating dislodged joints in drains; inspection of underfloor heating installations; inspection of concealed spaces at a road accident or in a collapsed building; inspection of large engines or turbines for electricity generation or other purposes; and marine applications such as inspection of bilges, engine bays, large marine engines, seacocks, muffler and exhaust systems.

In a method according to the invention, the inspection tool may take any of the forms defined above. Features described above in respect of the inspection tool of the invention may also be applied as appropriate to the method of the invention.

By way of example, an inspection tool embodying the invention will now be described with reference to the accompanying schematic drawings, of which:

Fig. 1 is a perspective view of the tool, excluding a series of rods to which the tool may be connected;

Fig. 2 is a sectional side view of a rod that may be screw connected end to end to other similar rods and that is plastically deformable;

Fig. 3 is a sectional side view of a rod that may be screw connected end to end to other similar rods and that incorporates a rotatable coupling; Fig. 4 is a sectional side view of a housing of a camera assembly; and

Fig. 5 is a side view of a modified form of the camera assembly. Referring first to Fig. 1, the inspection tool embodying the invention and shown in the accompanying drawings generally comprises a camera assembly 1, a display unit 2 including a display screen 3, and a rod 4.

The rod 4 is shown in Fig. 2 and has at one end a male screw threaded connector 5 and at the other end a female screw threaded connector 6. The male screw threaded connector 5 can be screwed into a female screw threaded connection 7 provided on a housing 8 of the camera assembly, shown in Fig. 4. The female screw threaded connector 6 can be screwed into a matching male screw threaded connector provided on the end of a series of rods that may each be of the same form as shown in Fig. 2, except that, as explained below, the rod 4 is plastically deformable whereas each rod of the series of rods may be elastically deformable. The series of rods may be of a kind known per se, and more particularly may be of the kind supplied in the product known as Cable Rod and sold by Super Rod Limited.

The rod 4 is designed such that it can be bent into a desired shape and will then remain in that shape until it is bent into a different shape. That contrasts with the series of rods to which the rod 4 is connected, in that each of that series of rods has a natural state in which it is straight, and can be bent into a different shape by elastic deformation, but will then return to a straight shape as soon as it is free to do so.

Fig. 3 shows a rod 9 that has a male screw threaded connection 10 at one end and a female screw threaded connector 11 at the opposite end, the female connector 11 incorporating a rotatable coupling as will now be described. The female connector 11 has an end cap 12 (shown by cross-hatched lines in Fig. 3) which is fixed to the end of the body 13 of the rod 9 after a sleeve 14 has been threaded onto the rod. The sleeve 14 has an externally screw threaded part 15 which is screwed onto a correspondingly internally threaded part 16 of a connector 17 thereby fastening together the parts 15 and 16. Whilst the end cap 12 prevents the parts 15 and 16 coming away from the body 13 of the rod 9, it allows free rotation of the parts.

The camera assembly 1 comprises the housing 8 and, within the housing, an infra red camera unit 18, an electric circuit module 19 and a rechargeable battery 20, those components being shown schematically by dotted lines in Fig. 4. Light sources 18A, which may be light emitting diodes, are mounted in the front of the housing 8 and illuminate the region in front of the camera unit. Each of the components is of a kind known per se and is not further described here. As can be seen from Fig. 4, the housing 8 comprises a main body part 8A and end parts 8B and 8C which are screwed onto opposite ends of the body part 8A. An aperture 21 in the wall of the main body part 8A provides a passageway for an aerial to project through the housing for transmitting a picture signal generated by the camera unit 18 and processed by the electric circuit module 19. The camera housing 8 is of circular, cylindrical shape, the camera unit 18 being mounted in the front of the housing 8 and having a direction of viewing along the longitudinal axis of the housing 8 through a central aperture in the end part 8B. The end part 8C carries the female connection 7 on the rear end of the housing 8 and, as shown in Fig. 4, the connection 7 is disposed on the longitudinal axis of the housing.

In use, a user connects the female connection 7 of the camera assembly 1 to the male connector 5 on the rod 4 and connects the female connector 6 on the rod 4 to the first of the series of rods. Other rods can then be screw connected to extend the length of the series of rods. The user can deform the rod 4 to a desired shape so as to alter the axis of the housing 8 of the camera assembly relative to the axis of the rod 4 at the end of the rod carrying the female connector 6, that end of the rod being coaxial with the end of the series of rods to which it is connected. A user is then able to insert the camera assembly 1 through a narrow passage and/or into a confined space in order to view a concealed place. The infra red camera unit 18 in the housing 8 sends a picture signal to the electric circuit module 19, providing a picture of the space in the field of view of the camera unit. The electric circuit module 19 transmits a picture signal via the aerial projecting through the aperture 21 to the display unit 2 where the picture is displayed on the display screen 3. As will be understood, the user positions the display screen 3 within his view or within the view of a second person.

In the description above one particular method is described but it will be appreciated that many modifications may be made to that method, some of which are described below.

The rod to which the plastically deformable rod 4 is connected may incorporate the rotatable coupling described above with reference to Fig. 3. In that case the camera assembly 1 can be arranged to adopt the same orientation (determined by gravity and the shape chosen for the rod 4), regardless of any rotation of the series of rods. For example, the camera assembly 1 can readily be arranged to view downwardly. An arrangement of this kind also provides added security because it makes it more unlikely that any connection will become unscrewed accidentally.

The rod to which the plastically deformable rod 4 is attached may also be made of a material, or covered with a material, that is luminescent or fluorescent. In that case a user may be better able to see the location of the camera assembly 1.

An on/off switch may be provided on or in the camera housing 8 for controlling the connection of the rechargeable battery 20. By arranging for the battery 20 to be connected only when the tool is in use, the length of time for which the tool can be used before being recharged can be considerably increased. To avoid inadvertent operation of the switch while the camera housing 8 is moving through a confined space, it may be advantageous to provide a switch inside the housing 8 and provide a facility for remotely operating the switch, for example by a magnetic card. In order to provide additional security for the fastening of the camera assembly 1 to the rod 4, the screw connection already described may be supplemented by a lock nut that provides a further screw connection between the camera assembly 1 and the rod 4. Whilst it is preferred to have a rod 4 which is plastically deformable, the invention can be carried out using only rods that are elastically deformable.

In one particular example of the invention, dimensions and properties of the components of the tool are approximately as follows:

external diameter of camera housing 8: 30 mm length of camera housing 8 (excluding the connection 7) : 90 mm volume of camera housing 8: 50 cm³ length of plastically deformable rod 4 : 125 mm diameter of plastically deformable rod 4: 6 mm length of elastically deformable rod: 125 mm diameter of elastically deformable rod: 5 mm flexural strength of elastically deformable rod: >500 flexural modulus of elastically deformable rod: >25

Fig. 5 shows a modified form of the camera assembly that is generally similar to the one described above and for which corresponding parts are designated by the same reference numerals. The assembly comprises a waterproof housing 8 in which a camera unit 18 and two light sources 18A (only one of which is visible in Fig. 5) , which may be light emitting diodes, are located. As shown in Fig. 5 the light sources 18A are located in the housing 8 behind the camera unit 18 and are positioned radially outwardly of the camera on opposite sides thereof. The front portion of the housing 8 comprises an end cap 31, which is made of translucent material so that light for the light sources 18A can pass through the end cap and especially a front face 31A of the end cap and light can also reach the camera unit 18 through the face 31A of the end cap. Furthermore the end cap 31 may be screwed onto the other part of the housing 8 and its front face 31A may incorporate a lens, the camera assembly then being able to be focussed by a user rotating the end cap 31 and thereby adjusting the distance between the end cap 31 and the camera .

An internal aerial (not shown) is provided within the end cap 31 so that no aperture is required in the end cap. The housing 8 shown in Fig. 5 also provides a switch for controlling the connection of the battery. At the rear of the housing there is a portion 33 of reduced diameter and to the rear of that a portion 34, to the rear end of which a female threaded connector element 35 is attached. These portions from an integral unit which is rotatable relative to the rest of the housing 8, comprising a main body part 36 and the end cap 31, to operate an internal switch not shown. Such arrangements are known per se and the details of the switch mechanism will not be described here. In the example described, each rotation of 90° is effective to switch the connection from one state to the other.

As will be understood the screw connection of the cap 31 to the main body part 36 of the housing 8 and the rotatable switching connection of the portions 33,34 relative to the main body part 36 are designed to maintain the waterproof nature of the housing 8.

The camera housing shown in Fig. 5 may be of similar overall dimensions as that described above. In one particular example, it has an overall diameter of 23 mm and a length (excluding the connector element 35) of 96 mm.

Claims

1. An inspection tool suitable for use in inspecting concealed places in a building, the tool comprising: a series of flexible rods detachably connectible together end to end, a camera assembly detachably connectible to one end of the series of rods and having, in a direction transverse to the longitudinal axis of the rods in the region of the connection to the camera when in use the rods are connected together and to the camera, a maximum dimension less than 50 mm, the camera assembly including a camera, a light source for illuminating a region in the field of view of the camera, a battery and an electric circuit for generating a wireless transmission from a signal received from the camera, and a display unit including a receiver for receiving the wireless transmission from the camera assembly and a display for displaying a picture generated from the wireless transmission.

2. An inspection tool according to claim 1, further including light emitting means on the camera assembly, or on the rods in the region of the camera assembly, for providing a visual indication of the position of the camera .

3. An inspection tool according to claim 2, in which the light emitting means comprises at least a portion of one of the rods, which portion is arranged to glow in the dark.

4. An inspection tool according to claim 3, in which said at least one portion is fluorescent.

5. An inspection tool according to claim 3, in which said at least one portion is luminescent.

6. An inspection tool according to any preceding claim, in which at least some of the rods are detachably connectible by screw connections.

7. An inspection tool according to any preceding claim, in which at least some of the rods are of substantially circular cross-section and have a diameter in the range of 5 to 15 mm.

8. An inspection tool according to any preceding claim, in which at least some of the rods are flexible and are able to be flexed repeatedly to a radius of curvature of less than 500 mm, without damage.

9. An inspection tool according to claim 8, in which at least some of the flexible rods are elastically deformable.

10. An inspection tool according to claim 9, in which at least some of the rods have a flexural modulus greater than 20.

11. An inspection tool according to any of claims 8 to 10, in which at least one rod is plastically deformable.

12. An inspection tool according to claim 11, in which said at least one plastically deformable rod is connectible between the camera and the other rods.

13. An inspection tool according to any preceding claim, in which the camera assembly is connectible to the series of rods by a detachable fastening and additional locking means are provided for ensuring the security of the fastening.

14. An inspection tool according to claim 13, in which the fastening is a screw fastening and the additional locking means is a locking nut.

15. An inspection tool. according to any preceding claim, in which the camera assembly is of generally cylindrical shape, the longitudinal axis of the cylinder being aligned with the longitudinal axis of the rods in the region of the camera when in use the rods are connected together and to the camera.

16. An inspection tool according to claim 15, in which the longitudinal axis of the cylinder is coincident with the longitudinal axis of the rods in the region of the camera when in use the rods are connected together and to the camera.

17. An inspection tool according to claim 16, in which the space occupied by the camera is less than 250 cm³.

18. An inspection tool according to any preceding claim, in which the camera assembly includes a waterproof housing in which the camera is located.

19. An inspection tool according to any preceding claim, in which the camera assembly includes a front end cap in which the camera is received, at least a portion of the front end cap being translucent.

20. An inspection tool according to any preceding claim, in which a facility for focussing the camera is provided.

21. An inspection tool according to any preceding claim, in which the camera is able to detect radiation of a wavelength in the infra red region of the spectrum.

22. An inspection tool according to any preceding claim, which is arranged such that when the camera assembly is in use detachably connected to the rods, the assembly is freely rotatable relative to the rods about the longitudinal axis of the rods in the region of the camera.

23. An inspection tool according to claim 22, in which a freely rotatable member is mounted on the end of a flexible rod and the camera is connected to the freely rotatable member.

24. An inspection tool according to any preceding claim, in which the battery is a rechargeable battery.

25. An inspection tool according to any preceding claim, in which the camera assembly further includes a switch for connecting and disconnecting the battery.

26. An inspection tool according to claim 25, in which the switch is activated by rotating one part of the camera assembly relative to another part.

27. An inspection tool according to any preceding claim, in which the light source is positioned behind the camera.

28. An inspection tool suitable for use in inspecting concealed places in a building, the tool comprising: a camera assembly for detachable connection to one end of a series of rods and having, in a direction transverse to the longitudinal axis of the rods in the region of the connection to the camera when in use the rods are connected together and to the camera, a maximum dimension less than 50 mm, the camera assembly including a camera, a light source for illuminating a region in the field of view of the camera, a battery and an electric circuit for generating a wireless transmission from a signal received from the camera, and a display unit including a receiver for receiving the wireless transmission from the camera assembly and a display for displaying a picture generated from the wireless transmission.

29. An inspection tool according to claim 28, further including light emitting means on the camera assembly for providing a visual indication of the position of the camera .

30. An inspection tool according to claim 24, in which the tool further comprises a rod for connection at one end to the camera assembly and for connection at the other end to a series of rods, and in which the light emitting means comprises at least a portion of the rod, which portion is arranged to glow in the dark.

31. An inspection tool according to any of claims 23 to 28, in which the tool further comprises a freely rotatable member for connection at one end to the camera assembly and for connection at the other end to a series of rods, for mounting the camera for free rotation relative to the rods .

32. An inspection tool suitable for use in inspecting concealed places in a building, the tool comprising: a series of flexible rods detachably connectible together end to end, at least some of the rods having a flexural modulus greater than 20, a camera assembly detachably connectible to one end of the series of rods, the camera assembly including a camera, a light source for illuminating a region in the field of view of the camera, and an electric circuit for transmitting a picture signal received from the camera to a remote location, and a display unit including a receiver for receiving the picture signal from the camera assembly and a display for displaying a picture generated from the signal.

33. An inspection tool suitable for use in inspecting concealed places in a building, the tool comprising: a series of flexible rods detachably connectible together end to end, at least some of the rods being of substantially circular cross-section and having a diameter in the range of 5 to 15 mm, a camera assembly detachably connectible to one end of the series of rods and having, in a direction transverse to the longitudinal axis of the rods in the region of the connection to the camera when in use the rods are connected together and to the camera, a maximum dimension less than 50 mm, the camera assembly including a camera and an electric circuit for transmitting a picture signal received from the camera to a remote location, and a display unit including a receiver for receiving the picture signal from the camera assembly and a display for displaying a picture generated from the signal.

34. An inspection tool suitable for use in inspecting concealed places in a building, the tool comprising: a camera assembly detachably connectible to one end of a series of rods, the camera assembly including a camera and an electric circuit for transmitting a picture signal received from the camera to a remote location, and a display unit including a receiver for receiving the picture signal from the camera assembly and a display for displaying a picture generated from the signal, wherein the tool includes one or more of the following features : (a) the tool further includes a series of flexible rods detachably connectible together end to end,

35. A method of inspecting a concealed place in a building, the method including the following steps: detachably connecting together a series of rods in end to end relationship, detachably connecting a camera assembly at one end of the series of flexible rods, the camera assembly including a camera and an electric circuit for transmitting a picture signal received from the camera to a remote location, inserting the camera into a confined space and manipulating the rods to move it through the confined space to a position within sight of the concealed place to be inspected, and transmitting a picture of the concealed space from the camera to a display unit at a location remote from the camera.

36. A method according to claim 35, in which the camera is freely rotatable relative to the rods.

37. A method according to claim 36, in which the camera is arranged to adopt a predetermined orientation on the end of the rods.

38. A method according to any of claims 35 to 37, in which the transmission of the picture to the remote location is a wireless transmission.

39. A method according to any of claims 35 to 38, in which the tool is as claimed in any of claims 1 to 34.