LIGHTING DEVICE

BACKGROUND OF THE INVENTION

[0001] This invention relates to a lighting device which is of compact and adjustable construction.

[0002] The invention is described hereinafter with particular reference to use in a dental or oral application but it is to be understood that this is exemplary only and is by no means limiting for, in general terms, the lighting device can be used in practically any application e.g. for use with a human, animal or otherwise, in which good lighting is required particularly in a small space or volume in which intricate work, close inspection or examination is to take place.

[0003] Dental work in an oral cavity calls for an adequate degree of illumination to enable the dentist to work effectively. Normally use is made of an overhead light or lights which are angled, as required, to shine directly into the oral cavity. Inevitably though at least part of the light is obstructed as the dentist does his work and the illumination level at the working location is then adversely affected.

[0004] One approach which has been adopted to counter the aforementioned situation makes use of a fibre optic light source which is attached to a drill or other work piece which is used by a dentist. To some extent this does solve part of the problem but the light source is ineffective if illumination is required when the instrument is not in use.

[0005] In another technique a small mirror which is used by a dentist to examine dental areas which otherwise are not directly visible, is fitted with a light source. The resulting assembly does allow for the illumination of dark areas in a person's mouth. However when dental work is carried out the light source and the mirror usually get covered in a mist or spray and the level of illumination is decreased. A further drawback is that the dentist may require both hands for carrying out a procedure and this means that the dentist cannot hold the mirror to illuminate the area at which work is done.

[0006] The use of a headlamp, i.e. a light which is carried on a band or other attachment secured to the dentist's head, can be effective in illuminating an oral cavity. The dentist's hands can however interrupt a light beam which is intended to illuminate a work location and, moreover, precise positioning of the light source on the user's head is needed.

[0007] Various other arrangements which make use of a light source located in or directed into an oral cavity have been proposed. In some applications light is used in a curing or photo polymerization role. Typical prior art lighting devices are disclosed in the specifications of the following US patents: 4375964, 4562832, 4629425, 4996976, 5152686, 5281134, 5408992, 5420768, 6159005, 6974321 , 6611110, 7210814, 7284981 , 7287981 and 7293990.

[0008] In US 5931670 light is transmitted from a fibre optic illuminator to a light projection tip of a dental suction appliance. Effectively a light source is produced inside the patient's mouth but a drawback is that the position of the light source is co-

incident with a suction end of the suction appliance. Independent adjustment of the light source relatively to the suction end is not possible.

[0009] From the aforegoing it is apparent that, at least for a dental application, a lighting device should be small, not interfere with dental work but usable to illuminate all parts of a patient's mouth, and should not discomfort the patient.

[0010] It is an object of the present invention to provide a lighting device which at least partly addresses the aforementioned factors.

SUMMARY OF INVENTION

[0011] The invention provides a lighting device which includes an elongate flexible member comprising at least two elongate electrical conductors which are encased in an electrically insulating material, at least part of the member being bendable, within limits, in a non-resilient manner to a desired shape, at least one light source which is connected to the conductors and which is located at or near one end of the member, and a connector for connecting the electrical conductors to an electrical source.

[0012] Preferably the light source is at least one light emitting diode.

[0013] Preferably the light source is mounted to or is in thermal communication with a thermally conductive body.

[0014] The thermally conductive body serves as a support for the light source and enables the light source to be electrically connected to the electrical conductors. At least one of the electrical conductors is in thermal contact with the thermally

conductive body and is able to conduct heat generated by the light source, away from the light source.

[0015] The lighting device may include a lens or other light dispersing arrangement located, at least, over the light source.

[0016] Preferably the light source produces colour corrected light i.e. light which is substantially at the wave length of natural sunlight. This feature also allows for shade taking (measuring) of teeth (in a dental application). This is not limiting though for other colours can be produced by changing the nature of the light source (LED) or by the use of one or more appropriate filters and a number of LEDs.

[0017] If necessary a particular colour can be obtained through the use of multiple light sources, each emitting light of a different colour, and with the emitted lights blended to produce a desired colour.

[0018] The conductors may be made from any suitable material but preferably are made from copper which is malleable. This feature enables the copper conductors to be bent in a non-resilient manner. In this respect "non-resilient" means that there is no meaningful tendency for the conductors, once bent or deformed, to tend to resume a former position or arrangement. This materially assists in the adjustability of the member and hence of the orientation and position of the light source, during use of the lighting device. To achieve this feature each conductor is preferably a single strand of copper wire of a suitable thickness and malleability.

[0019] At least one conductor also acts as a heat sink. Preferably both conductors are used in this way. It is therefore preferred that the cross sectional area of each conductor is substantially greater than what is necessary taking into account only the current carrying capacity required in order to energise the light source.

[0020] The light source is preferably mounted inside a small housing. The light source may be orientated so that it projects in an axial direction i.e. in a direction which is substantially coincident with a longitudinal axis of the elongate member. Preferably though the light source projects light mainly transversely to the axial direction - it has been found that this increases the utility of the light source. A light shield may be positioned adjacent the light source to restrict or prevent glare from the light source reaching the operator e.g. a dentist.

[0021] The lighting device may include a mechanism for adjusting the current or voltage applied to the light source in order to adjust the light output of the light source.

[0022] The electrical source which is used to power the light source may be a battery, which may be rechargeable, or power may be derived from a mains supply. In the latter case use is made of double insulation techniques in order to ensure that the light source is inherently safe.

[0023] The electrical source may be rechargeable by engagement with a charging station. Preferably the electrical source is in a housing with a control to turn the light source on or off, and to adjust the light output of the light source.

[0024] To allow for the lighting device to be used repeatedly in a safe and hygienic manner the lighting device may be provided in combination with a protective coating which is removable and disposable. The protective coating may be in the form of a thin plasties sheath which at least in the region of the light source is light transmissive. The sheath may be enclosed around the elongate member by means of a zip-type or other easily actuated, and easily released, fastening arrangement.

[0025] In a dental application the lighting device may be provided with means for retaining the elongate member engaged with a patient's mouth. The retaining means may be in the form of a hook which is engageable in a non-obtrusive and painless manner with the patient's mouth. The nature of engagement is such that the light source, by bending the elongate member appropriately, is adjustable independently, to a substantial extent, relatively to the retaining mechanism.

[0026] In a preferred arrangement of the invention the lighting device includes one or more attachment means, each in the nature of a clip or similar mechanism, which are used to attach the elongate member to a suction appliance e.g. a low volume suction tube of the kind used in dental work. Other attachment devices can be used and the invention is not limited in this respect. For example the lighting device could be attached to a patient's cheek, or secured to a bib or other support worn by the patient.

[0027] Two or more of the lighting devices can be used, if required, for example mounted to a common support, to enable a particular area or location to be illuminated from different sides or in different directions.

[0028] Depending on the nature of the application or the intended use of the lighting device it is possible for the lighting device to be engaged, for example with a patient's body, using any suitable fixing or mounting arrangement. The invention is not limited in this regard.

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The invention is further described by way of examples with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a lighting device according to one form of the invention; Figure 2 is a side view in cross section of the lighting device shown in Figure 1 ;

Figure 3 is a view in perspective, on an enlarged scale, of a light emitting end of the lighting device shown in Figure 1 ;

Figure 4 illustrates a power supply connected to an end of the lighting device which is remote from the light emitting end shown in Figure 3; Figure 5 depicts how the lighting device can be attached to a dental suction appliance;

Figure 6 shows how the arrangement in Figure 5 can be used;

Figures 7 and 8 illustrate a hygienic protective shield or sheet engaged with the lighting device; Figure 9 shows a variation of the device in Figure 3;

Figure 10 shows the device of Figure 9, ready for use,

Figure 11 shows a charging arrangement for another form of a power supply, for the device;

Figures 12 and 13 show aspects relating to the use of the power supply; and Figure 14, which is similar to Figure 6, shows the lighting device of Figure 9 in use.

DESCRIPTION OF PREFERRED EMBODIMENTS

[0030] Figures 1 and 2 of the accompanying drawings are perspective and cross sectional side views respectively of a lighting device 10 according to the invention.

[0031] The device includes an elongate slender member 12, a light emitting arrangement 14 at one end of the member 12, a connector 16 at an opposing end of member and a connector 18 at an intermediate position between the arrangement 14 and the connector 16.

[0032] The member 12, between the light emitting arrangement 14 and connector

18, is formed, essentially, from two elongate malleable copper conductors 20 and 22 respectively which have relatively large cross sectional areas and which are encased in a pliable, inert and hygienically acceptable plastics material 24 of any suitable kind known in the art. As is shown in the inset drawing to Figure 2 each conductor comprises a single strand of copper wire of a suitable malleability. The cross sectional area of the conductor is greater than what is required for carrying current to the lighting arrangement for the conductor also acts as a thermal sink and acts to conduct heat away from the lighting arrangement. Also, the conductor is used to provide an easily adjustable mechanical support for the lighting arrangement. These aspects are further described hereinafter. The nature of the construction of the elongate member 12, in this respect, is such that it can be bent in a non-resilient manner at least within limits with relative ease. In other words if the member 12 is

bent it remains in its bent configuration and does not naturally, due to inherent resilient forces, attempt to restore itself to its original unbent position.

[0033] The light emitting arrangement 14 is shown in enlarged detail in Figure 3. An LED (light emitting diode) 26 is electrically and thermally connected to a mounting plate 28. The mounting plate constitutes a thermally conductive body which is in thermal contact with the LED. The plate, which is made from an electrically conductive material, is divided into upper and lower halves 28A and 28B which are electrically separated by means of an insulating divide 30. The copper conductor 20 is connected to the upper half and the copper conductor 22 is connected to the lower half. These connections electrically connect the conductors to the plate. Also, as the conductors are metallic, a thermal connection is effected between the conductors and the plate.

[0034] The plate 28 is held inside a housing 32 which comprises two halves only one of which, the lower half 32A, is shown in Figure 3. The upper half of the housing is engageable with the lower half to enclose the light emitting diode and mounting plate in a protective chamber.

[0035] The housing 32 has appropriate locating formations to ensure that the copper conductors are retained in desired positions.

[0036] The light emitting diode 26 is retained in position by means of a locating plate 38. A suitable light dispersing lens 40 is positioned over the light emitting diode, engaged with the housing. The light emitting diode is axially aligned with the elongate flexible member 12.

[0037] The connector 18 is permanent and its primary function is to provide a formation on the member 12 which facilitates handling of the member.

[0038] The connector 16 is used to connect the member 12 to electrical leads 41 of conventional construction. These leads have cross sectional areas which are considerably less than the cross sectional areas of the copper conductors for the leads 41 are not called upon to conduct heat, in any meaningful way, from the light emitting diode 26.

[0039] Figure 4 shows a battery pack 42 which is connected to the leads 41. The battery pack is of any suitable configuration and preferably includes one or more rechargeable batteries 44 in a housing 46.

[0040] Referring to Figure 5 and to Figure 6 in a preferred embodiment of the invention the lighting device 10 is engageable with one or more attachment clips 50 which, in themselves, are flexible. The clips are made for example from an appropriate flexible plastics material. In many dental applications use is made of a dental suction appliance, of known construction, which includes an elongate disposable plastic tube 52 with a suction end 54. The tube extends from a base arrangement 56. The construction and use of the suction appliance are not further described herein for they are known in the art. The clips 50 and designed to engage with a snap fit with the tube 52.

[0041] The tube 52 of the suction appliance is bendable into any suitable form, during use, and normally is bent into a hook shape so that it is retained in position at a desired location by engagement with a part of the patient's mouth. This provides a

ready and effective support for the lighting device which is, in turn, engaged with the tube. The elongate member 12 can be bent and manipulated as required to illuminate the patient's mouth. The amount of light emitted by a modern light emitting diode is significant and heat build-up must be minimised at least for the following reasons:

(a) light output efficiency decreases with increasing junction temperature,

(b) excessive heat build-up in the LED region may cause burns if the region comes into contact with human skin, and

(c) the LED junction must not be allowed to exceed 8O ⁰ C to avoid a shift in the colour spectrum of the emitted light. This is critical because the colour temperature must be controlled within a specified range.

[0042] The housing which contains the LED is restricted in respect of its maximum volume. Consequently the facility for removing excess heat from the LED is limited. For this reason use is made of the thermally conductive wires.

[0043] The two wires are uninsulated copper wires that are extruded in a plastic sheath. Each copper wire is not stranded and consists of a solid wire of about 1 mm diameter. Apart from supplying electrical power to the LED the copper wires also provide support for the LED housing. Support can only be provided via a solid wire. The wire dimensions however must be such that the support can be bent and manipulated in order to position the light source in the most convenient location.

[0044] Experiments have shown that a 1mm diameter for each copper wire is suitable for easy manipulation of the light source and there is no spring-back or

memory effect of the wires once formed into the required shape. Also, adequate strength is available to support the light source.

[0045] For an LED the power consumption, applied voltage, current, operating temperature and light output are interrelated. The heat sink effect provided by the copper wires is noticeable. The junction temperature of the LED is decreased and the flux output of the LED is increased. An objective in this respect is to maintain the temperature of the housing which contains the light source below 40 ⁰ C.

[0046] The amount of light emitted by the diode can be controlled by making use of a voltage or current adjustment device (not shown) which, preferably, is engaged with the housing 42.

[0047] The suction appliance shown in part in Figures 5 and 6 is disposable and is used once. The lighting device of the invention is however substantially more expensive and for this reason it is desirable to be re-usable although, possibly, not indefinitely. The lighting device can be sterilised and disinfected after each use. Alternatively or additionally use is made of an elongate sheath 60 of the kind shown in Figure 7. The sheath is made from a flexible, low cost safe, and hygienic plastics material which at least at one end 62 is light transmissive. The sheath is provided in sheet form and, as shown, is wrapped around the lighting device. Adjacent edges of the sheet can be secured to each other by means of an adhesive or zip mechanism 64 which is easy to use, in order to secure the sheath in position. Conversely, the sheath can readily be detached from the member 12 after use. The sheath is then disposed of and the lighting device is sterilised as appropriate and disinfected. A fresh sheath is then engaged with the lighting device for subsequent use.

[0048] The lighting device effectively and efficiently illuminates the oral cavity during all aspects of dental work. It is easily held in position and can be adjusted as required. To a substantial extent the use of the lighting device of the invention enables overhead lights and similar mechanisms to be dispensed with.

[0049] The light emitting diode 26 in the arrangement 14 of Figure 3 is positioned to direct light in a direction which is axially aligned with the elongate flexible member 12. This is not necessarily optimal. Figure 9 shows an arrangement 14A in which a light emitting diode 26, mounted to a plate 28 is turned through 90° relatively to what is shown in Figure 3 so that the diode is transversely orientated relatively to the longitudinal axis of the member 12. It has been found that this facilitates placement of the light source in a patient's mouth to achieve optimal illumination conditions. On the other hand light from the LED 26 may be directed into the eyes of an operator e.g. a dentist. To limit this unwanted effect a shield 60 is attached to the member 12. The shield is made from a relatively soft opaque material and has rounded corners. The shield is positioned to prevent light from the LED from reaching the eyes of a dentist. This aspect is shown in Figure 14 which illustrates light 62 from the LED being directed sideways into a mouth of a patient, with the shied 60, which is relatively small, preventing or restricting light from exiting directly through the mouth of the patient to the eyes of a dentist.

[0050] Figure 4 shows a battery-pack 42 used for powering the LEDs. Figure 12 shows a modified battery-pack 42A which is detachably engageable with the elongate flexible member 12. The battery-pack has a socket 66 into which a connection terminal 68 at one end of the member 12 is insertable. Rechargeable

batteries, not shown, are contained in a housing 46A. The housing has three control buttons 70, 72 and 74 respectively. The central button 72 is used for turning the LED on or off. The button 70 is operated in step fashion and, with each actuation, causes the light output from the LED to be increased in a step change. Conversely actuation of the button 74 causes light output from the LED to be decreased, again in step fashion. The battery pack 42 is small and therefore easily movable. The pack can be attached to a dentist's chair or any other suitable structure, as required, for example by using Velcro™ strips, magnets or the like. The invention is not limited in this respect.

[0051] The housing 46A can be recharged in the manner shown in Figure 11. Use is made of a docking station 80 which has two relatively large sockets 82 and 84. Each socket can accommodate a respective housing 46A. Terminals 86 in a base of the socket are automatically electrically engaged with corresponding terminals on the housing and, in this way, the battery-pack is automatically recharged. Power for recharging comes from a mains supply, not shown, which is transformed and rectified by means of suitable apparatus 90 to provide a controlled voltage which is applied to the respective battery packs. This approach allows for the battery-pack to be disengaged from the docking station and hence increases mobility of operation during use of the light source.