This invention relates to lighting units and in particular to lighting units for passenger vehicles.

Passenger vehicles such as aircraft, trains, coaches and ships are known to provide an overhead unit which typically includes a reading light. Typically, such reading lights are provided in a passenger service unit which typically includes a passenger air supply device and controls, oxygen masks and attendant call lights. The assembly is provided by the manufacturer and installed in the aircraft as a unit.

Existing passenger service units typically include a halogen or an incandescent reading light. More recent passenger service units may include an LED lighting unit. Existing incandescent or halogen reading lights have a number of undesirable features. Halogen lamps typically have a colour temperature of <3000 kelvin which is undesirable due to the amber colour and lack of ability to modify the colour output. Additionally, halogen and early LED lamps produce a large amount of heat which is undesirable in a passenger vehicle, particularly an aircraft. Early LED units typically incorporate a heat dissipation mechanism (heat sink) . Halogen lamps use a large amount of energy to produce the light which is undesirable in an aircraft due to limited energy supply. Furthermore, halogen lamps have proven to be unreliable in use which can cause passengers inconvenience in travel and adds to maintenance costs. It will be appreciated that in new passenger service units, an LED lighting unit can be incorporated. However, it is desirable to replace the incandescent or halogen lighting units of existing passenger service units to utilise an LED light. Retrofitting an LED light has been previously described but it requires adaptation of the passenger service unit.

It is an object of the present invention to provide a simple, effective method of retrofitting an LED light to a passenger service unit having an incandescent or halogen light fitting. A further object of the invention is to provide improved passenger lighting, particularly in an aeroplane.

According to a first aspect of the invention there is provided an LED lighting assembly for retrofitting an LED lighting unit to a reading light unit in a passenger service unit in a passenger vehicle, the LED lighting assembly comprising a cassette having a lens, a printed circuit board having at least one LED bulb mounted thereon; an optic, surrounding the or each bulb and extending between the printed circuit board and the lens, and an electrical connector adapted to be connectable to a bulb holder in the reading light unit and wherein the lens is arranged to provide a predetermined light pattern defining a personal passenger space .

Preferably the lens is a lenticular lens According to a second aspect of the invention there is provided a method of retrofitting an LED light assembly in accordance with the first aspect of the invention to a passenger vehicle the method comprising removing an incandescent or halogen bulb and front glass from a reading light unit in a passenger service unit, connecting the electrical connector to a bulb holder in the reading light unit and inserting the cassette into the reading light unit.

According to another aspect of the invention there is provided an LED lighting assembly comprising a cassette having a lens, a printed circuit board having at least one LED bulb mounted thereon; an optic, surrounding the or each bulb and extending between the printed circuit board and the lens, and an electrical connector and wherein the lens is arranged to provide a predetermined light pattern defining a personal passenger space.

Preferably the predetermined light pattern is non-circular.

Preferably the electrical connector is arranged to have a dummy bayonet fitting and can be readily connected to an existing bayonet fitting for an incandescent or a halogen bulb fitting in an existing reading light unit located in a passenger service unit. The electrical connector can be readily connected to the existing power supply unit in the passenger service unit. Advantageously, no replacement of the existing power supply unit or wiring is required to retrofit the LED lighting assembly to an existing reading light unit in a passenger vehicle such as an aeroplane. An advantage of the present invention is that the existing reading light unit is re-used. Desirably leads extend from the electrical connector to the printed circuit board. Preferably the electrical connector is a dummy bayonet cap.

Preferably the cassette has a bayonet fitting that fits directly into the existing reading light in place of an existing glass cover and has tabs arranged to cooperate with recesses in a side of the reading light unit to secure the side walls of the cassette in place . Alternatively the cassette may have a screw fitting. Other fittings can be envisaged depending on the fittings in the reading light.

Desirably the cassette comprises a frame connected to the side walls. The frame is preferably able to rotate relative to the side walls when the cassette has been installed in the reading light unit. Preferably the frame supports and desirably retains the lens.

Preferably a tamper proof fitting is used to secure the cassette in position. In a preferred embodiment a temporary mounting device is provided. Once the cassette has been secured in place in the reading light unit the temporary mounting element can be removed. Preferably the cassette cannot be removed from the reading light unit once the temporary mounting device has been removed. In a preferred embodiment the temporary mounting device comprises mounting pins which desirably extend through the frame and connect the frame to the side walls. Preferably once the mounting pins are removed the frame of the cassette is arranged to be able to rotate relative to the side walls of the cassette . The cassette is secured in place in the reading light unit by the tabs. A passenger is not able to dismantle the reading light as the side walls cannot be moved. Only the frame can be accessed and the frame rotates freely relative to the side walls.

An advantage of the present invention is that the cassette comprises the LED lamp, the electronics on the printed circuit board and the lens in a single assembly. The cassette can be readily fitted to the passenger service unit without requiring any specialist skill. Retrofitting of the LED lights can be readily carried out without requiring specialist service personnel. In some cases it may be possible to carry out a replacement programme on an ad hoc basis replacing existing halogen lights as the bulbs fail.

Another feature of the invention is that the cassette comprises a lens which is arranged to provide a predetermined light pattern defining a personal passenger space .

Preferably the o lens is arranged to provide a light pattern that provides at least a non- circular light pattern and preferably a partially quadrilateral shaped light pattern. Advantageously such a light pattern can define a passenger space . Desirably the light pattern is uniformly distributed within the desired light pattern. In a preferred embodiment the light pattern is selected from the group comprising a quadrilateral distribution, a square distribution or a squircle distribution. A squircle is a mathematical shape with properties between those of a square and those of a circle. In a preferred embodiment the lens comprises at least one lenticular lens. Preferably two lenticular lenses are used to create the desired light distribution. In a particularly preferred embodiment the lens comprises a first lenticular lens having an array orientated in a first direction. The lens preferably comprises a second lenticular lens . Preferably the second lenticular lens has an array is orientated perpendicular to the first lenticular array.

It will be appreciated that the use of two lenticular lenses with arrays extending in substantially perpendicular orientations produces a light distribution that is substantially square or a squircle .

Variations in the lens can be envisaged to provide alternative light pattern distributions.

In some embodiments a mask may be provided. Preferably the mask is provided between the first and the second lenticular arrays. The mask may also act as a reflector. Preferably the mask is arranged to provide a more uniform light distribution in the pattern.

In some preferred embodiments the mask may be shaped in a cross. Other masking patterns may be selected to provide alternative light distributions. Provision of a defined quadrilateral light pattern has been found to improve a passenger' s sense of personal space and privacy. A defined light distribution prevents light spill over into adjacent seats and prevents difficulties that can occur when adjacent passengers are trying to sleep and to read.

In a preferred embodiment the LED light assembly comprises an adjustable aperture means which comprises a mechanism arranged to be able to vary a radius of an opening in aperture means. Desirably the adjustable aperture means comprises a diaphragm. The diaphragm may be continuously adjustable from a wide open to a reduced or closed aperture or may be adjustable between predetermined aperture sizes . The radius of the opening in the reduced aperture positon is smaller than the radius of the opening in a large aperture position. The diaphragm may comprise 5 or more rotatable blades. The blades may be straight or curved. There may be from 5 to 30 blades or more preferably from 6 to 10 blades or most preferably from 7 to 9 blades. The mechanism is preferably arranged to be able to rotate the blades moving them from a closed position to an open position.

Preferably the aperture means can be locked in a desired position.

It has been appreciated that the aperture means can be used to control an amount of light output from the LED light unit. As the light output is reduced an area covered by the output light is reduced. It will be appreciated that a reduction in the light output reduces a size of the predetermined light pattern and this further reduces a size of the passenger space lit by the light from the light unit. It will be appreciated that the LED light assembly assists in preventing light from spilling over from one passenger space to an adjacent passenger space.

In one embodiment the aperture adjustment means is used in combination with means providing a non-circular light distribution pattern but it will be appreciated that the adjustable aperture means can be used to adjust a size of the light distribution pattern to prevent spill over of the light distribution pattern into an adjacent passenger space .

Desirably the aperture means is provided adjacent the lens. The aperture adjustment means may be located above the lens within the LED light assembly between the lens and the LED bulb. In a preferred example the aperture adjustment means is provided within the cassette.

Preferably the aperture means has an adjuster mechanism enabling a size of the aperture to be controlled by adjusting the radius of the diaphragm. Desirably a lock means is also provided. It has been appreciated that the aperture means may be used to control a total light output from the light assembly and that this may enable the LED light assembly to be used in a number of different types of aircraft. A distance from an overhead bulkhead in which the LED light assembly is located to a passenger seat can vary from one type of plane to another. The aperture means allows a total light output to be controlled and consequently the size of a light distribution pattern at a particular distance may be adjusted. Desirably an LED bulb with a high lumen output can be used with the aperture means adjusted to have a reduced opening in a plane with a relatively shorter distance from the bulkhead to the seat and the same LED bulb assembly can be used with the aperture means adjusted to have a relatively wider opening in a plane with a relatively greater distance from the bulkhead to the passenger seat.

Desirably the LED bulb is arranged to provide a colour temperature of from 2000 kelvin to 10 000 kelvin and preferably from 3000 kelvin to 7000 kelvin and more preferably from 3500 kelvin to 5000 kelvin. In some cases the colour temperature can be selected to suit a desired lighting situation. Different colour temperatures may be selected depending on other factors such as whether the light is providing mood lighting; night time lighting or a reading light. In a preferred embodiment the colour temperature is less than 4500 kelvin or more preferably lower than 4000 kelvin and most preferably less than 3700 kelvin. Desirably the colour temperature is greater than 3500 kelvin. In a preferred embodiment the colour temperature is greater than 3500 kelvin and less than 4200 kelvin. It is well known that LED lighting has other advantages in that the heat output is much lower than the heat output of incandescent or halogen lights. The use of LED lights reduces the impact of lighting on the environmental temperature. Additionally the heat output to the passenger service unit is also reduced so improving the safety of the unit. The power used by LED lights is much less than the power required by halogen lights and the LED light units are more reliable . In some preferred embodiments the light assembly is modified to provide an airflow through the assembly. Desirably air can be drawn though the reading light assembly and over the LED bulb and driver circuitry in the printed circuit board to reduce heat build-up in the LED bulb and in the printed circuit board. It has been appreciated that the printed circuit board can be sensitive to heat retention and that heat retention can degrade the reliability of the LED unit. Heat retention can potentially over a period of time reduce the in-service lifetime of the reading light assembly. Desirably at least a portion of the plastic parts of the reading light assembly are removed. Preferably the portion of the plastic parts which have been removed are arranged such that air can flow into and through the reading light assembly. In a preferred embodiment at least 5% of an area of the plastic part is removed, or more preferably at least 10% of the plastic parts are removed. Most preferably at least 20% of the area of plastic parts is removed.

It is preferably that the removed portions are in the form of openings in one or more parts of the reading light assembly. Preferably one or more openings are provided in the frame surrounding the lens. Openings may also be provided in the side walls of the LED light assembly. Preferably further openings are provided the printed circuit board on which the LED light bulb is mounted. Alternatively the printed circuit board is mounted such that there are openings around the printed circuit board and the housing such that air can pass around the printed circuit board. It is desired that the relative arrangement of the openings in internal and external housing of the LED light assembly is such that air is drawn into the LED light assembly and into the cassette and then over the printed circuit board and desirably also over the LED bulb in order to dissipate heat.

It will be appreciated that it is also desirable that an exit means for the air is also provided to draw air through the reading light assembly. The exit means may comprise additional openings in an upper part of the cassette .

Alternatively the LED light assembly may be arranged such that gaps are provided between connecting parts or openings are provided in internal and/or external parts of the assembly. In a preferred embodiment there is provided an electrical connector arranged such that air can flow through the electrical connector. Preferably the electrical connector is a dummy bayonet cap is provided with at least an opening in the region of the leads. Preferably the bayonet cap has further openings to encourage airflow through the cap . In some embodiments the bayonet cap is self-sprung and preferably catches arranged to hold the bayonet cap in place are arranged as tabs over an open portion of the cap. Desirably an internal channel and an upper opening are provided. It will be appreciated that the example having a number of openings in the LED lighting unit may be used in conjunction with other LED light units which do not have a predetermined light distribution pattern having at least a partially quadrilateral shape . The example having opening may be used to increase heat dissipation in standard LED light units. Similarly the disclosed electrical connector in the form of a dummy bayonet cap may be used in conjunction with a standard LED light unit.

According to another aspect of the invention there is provided an LED lighting assembly comprising a cassette having a lens, a printed circuit board having at least one LED bulb mounted thereon; an optic, surrounding the or each bulb and extending between the printed circuit board and the lens, and an electrical connector and wherein the lens is arranged to provide a predetermined light pattern defining a personal passenger space the predetermined light pattern being non-circular.

Desirably the lens is a lenticular lens.

The LED lighting assembly may be adapted to be suitable for retrofitting an LED lighting unit to a reading light unit in a a passenger service unit in a passenger vehicle . The LED lighting assembly may comprise an electrical connector adapted to be connectable to a bulb holder in the reading light unit.

Preferably the predetermined light pattern comprises at least partially of a quadrilateral shape . More preferably, the predetermined pattern is one of a square, a rectangle or a squircle . In one example the lens comprises at least a first lenticular lens and a second lenticular lens. In a preferred example the lens comprises a first lenticular lens having an array arranged in a first direction and a second lenticular lens having an array orientated at an angle to the first array. The lens may preferably be arranged such that the second lenticular array is orientated perpendicular to the first lenticular array.

In one example a mask may be provided. The mask may be provided between the first and the second lenticular lenses. In one example the mask is cruciform shaped. Preferably the LED bulb is selected to provide a colour temperature of from 2000 kelvin to 10 000 kelvin and preferably from 3000 kelvin to 7000 kelvin and more preferably from 3500 kelvin to 5000 kelvin or most preferably from 3500 kelvin to 4200 kelvin. In a preferred example the cassette has a tamper proof connection to the reading light unit which in one example is in the form of removable mounting pins.

In one example the electrical connector comprises a dummy bayonet fitting. The electrical connector may comprise at least partially an open channel and an exit such that air can pass through the connector. The electrical connector may comprise self- sprung clips.

In one example the LED light assembly is arranged such that air can flow into and through the assembly comprises a number of apertures in at least an outer part of the cassette and a relative arrangement of the apertures is such that air is drawn into the cassette and over the printed circuit board. In a preferred example the apertures are formed by the removal of at least a portion of the plastic parts of the assembly and wherein at least 5% of an area of a plastic part is removed. In some examples the openings may be provided in the frame of surrounding the lens and optionally in the printed circuit board.

The LED light assembly may further comprise an aperture adjustment means.

According to another aspect of the invention there is provided an LED lighting assembly comprising a cassette having a lens, a printed circuit board having at least one LED bulb mounted thereon; an optic, surrounding the or each bulb and extending between the printed circuit board and the lens, and an electrical connector unit and wherein the lens is arranged to provide a predetermined light pattern defining a personal passenger space and the lens comprising a first lenticular lens having an array arranged in a first direction and a second lenticular lens having an array orientated at an angle to the first array.

The LED lighting assembly may be adapted to be suitable for retrofitting an LED lighting unit to a reading light unit in a passenger service unit in a passenger vehicle . The LED lighting assembly may comprise an electrical connector adapted to be connectable to a bulb holder in the reading light unit.

It will be appreciated that an adjustable aperture means may be used in combination with the lens.

Preferably the predetermined light pattern is non-circular and preferably comprises at least partially of a quadrilateral shape . Preferably, the predetermined pattern is one of a square, a rectangle or a squircle . The lens may preferably be arranged such that the second lenticular array is orientated perpendicular to the first lenticular array.

In one example a mask may be provided. The mask may be provided between the first and the second lenticular lenses. In one example the mask is cruciform shaped.

Preferably the LED bulb is selected to provide a colour temperature of from 2000 kelvin to 10 000 kelvin and preferably from 3000 kelvin to 7000 kelvin and more preferably from 3500 kelvin to 5000 kelvin or most preferably from 3500 kelvin to 4200 kelvin.

In a preferred example the cassette has a tamper proof connection to the reading light unit which in one example is in the form of removable mounting pins.

In one example the electrical connector comprises a dummy bayonet fitting. The electrical connector may comprise at least partially an open channel and an exit such that air can pass through the connector. The electrical connector may comprise self- sprung clips.

In one example the LED light assembly is arranged such that air can flow into and through the assembly comprises a number of apertures in at least an outer part of the cassette and a relative arrangement of the apertures is such that air is drawn into the cassette and over the printed circuit board. In a preferred example the apertures are formed by the removal of at least a portion of the plastic parts of the assembly and wherein at least 5% of an area of a plastic part is removed. In some examples the openings may be provided in the frame of surrounding the lens and optionally in the printed circuit board.

According to another aspect of the invention there is provided an LED lighting assembly comprising a cassette having a lens, a printed circuit board having at least one LED bulb mounted thereon; an optic, surrounding the or each bulb and extending between the printed circuit board and the lens, and an electrical connector and wherein the lens is arranged to provide a predetermined light pattern defining a personal passenger space and wherein the LED lighting assembly comprises a number of apertures in at least an outer part of the cassette and a relative arrangement of the apertures is such that air is drawn into the cassette and over the printed circuit board.

Desirably the lens is a lenticular lens.

The LED lighting assembly may be adapted to be suitable for retrofitting an LED lighting unit to a reading light unit in a passenger service unit in a passenger vehicle . The LED lighting assembly may comprise an electrical connector adapted to be connectable to a bulb holder in the reading light unit.

It will be appreciated that an adjustable aperture means may be used in combination with the lens.

Preferably the predetermined light pattern is non-circular and preferably comprises at least partially of a quadrilateral shape. Preferably, the predetermined pattern is one of a square, a rectangle or a squircle . In one example the lens comprises at least a first lenticular lens and a second lenticular lens. In a preferred example the lens comprises a first lenticular lens having an array arranged in a first direction and a second lenticular lens having an array orientated at an angle to the first array. The lens may preferably be arranged such that the second lenticular array is orientated perpendicular to the first lenticular array.

In one example a mask may be provided. The mask may be provided between the first and the second lenticular lenses. In one example the mask is cruciform shaped. Preferably the LED bulb is selected to provide a colour temperature of from 2000 kelvin to 10 000 kelvin and preferably from 3000 kelvin to 7000 kelvin and more preferably from 3500 kelvin to 5000 kelvin or most preferably from 3500 kelvin to 4200 kelvin. In a preferred example the cassette has a tamper proof connection to the reading light unit which in one example is in the form of removable mounting pins.

In one example the electrical connector comprises a dummy bayonet fitting. The electrical connector may comprise at least partially an open channel and an exit such that air can pass through the connector. The electrical connector may comprise self- sprung clips.

In a preferred example the apertures are formed by the removal of at least a portion of the plastic parts of the assembly and wherein at least 5% of an area of a plastic part is removed. In some examples the openings may be provided in the frame of surrounding the lens and optionally in the printed circuit board.

According to another aspect of the invention there is provided an LED lighting assembly comprising a cassette having a lens, a printed circuit board having at least one LED bulb mounted thereon; an optic, surrounding the or each bulb and extending between the printed circuit board and the lens, and an electrical connector the lens being arranged to provide a predetermined light pattern defining a personal passenger space wherein the electrical connector comprises a number of openings arranged such that air can flow through the connector. The LED lighting assembly may be adapted to be suitable for retrofitting an LED lighting unit to a reading light unit in a passenger service unit in a passenger vehicle . The LED lighting assembly may comprise an electrical connector adapted to be connectable to a bulb holder in the reading light unit.

It will be appreciated that an adjustable aperture means may be used in combination with the lenslens.

Preferably the predetermined light pattern is non-circular and preferably comprises at least partially of a quadrilateral shape. Preferably, the predetermined pattern is one of a square, a rectangle or a squircle .

In one example the lens comprises at least a first lenticular lens and a second lenticular lens. In a preferred example the lens comprises a first lenticular lens having an array arranged in a first direction and a second lenticular lens having an array orientated at an angle to the first array. The lens may preferably be arranged such that the second lenticular array is orientated perpendicular to the first lenticular array. In one example a mask may be provided. The mask may be provided between the first and the second lenticular lenses. In one example the mask is cruciform shaped.

Preferably the LED bulb is selected to provide a colour temperature of from 2000 kelvin to 10 000 kelvin and preferably from 3000 kelvin to 7000 kelvin and more preferably from 3500 kelvin to 5000 kelvin or most preferably from 3500 kelvin to 4200 kelvin.

In a preferred example the cassette has a tamper proof connection to the reading light unit which in one example is in the form of removable mounting pins.

In one example the electrical connector comprises a dummy bayonet fitting. The electrical connector may comprise at least partially an open channel and an exit such that air can pass through the connector. The electrical connector may comprise self- sprung clips. In one example the LED light assembly is arranged such that air can flow into and through the assembly comprises a number of apertures in at least an outer part of the cassette and a relative arrangement of the apertures is such that air is drawn into the cassette and over the printed circuit board. In a preferred example the apertures are formed by the removal of at least a portion of the plastic parts of the assembly and wherein at least 5% of an area of a plastic part is removed. In some examples the openings may be provided in the frame of surrounding the lens and optionally in the printed circuit board. According to another aspect of the invention there is provided an LED lighting assembly the LED lighting assembly comprising a cassette having a lens, a printed circuit board having at least one LED bulb mounted thereon; an optic, surrounding the or each bulb and extending between the printed circuit board and the lens, and an electrical connector and wherein the lens is arranged to provide a predetermined light pattern defining a personal passenger space wherein the LED light assembly further comprise an adjustable aperture means.

The LED lighting assembly may be adapted to be suitable for retrofitting an LED lighting unit to a reading light unit in a passenger service unit in a passenger vehicle . The LED lighting assembly may comprise an electrical connector adapted to be connectable to a bulb holder in the reading light unit.

It will be appreciated that the adjustable aperture can be used in combination with the lens in the LED lighting unit to provide a light distribution pattern which is at least non-circular and preferably at least partially quadrilateral. Preferably, the predetermined light distribution pattern is one of a square, a rectangle or a squircle. Alternatively the adjustable aperture may be used in isolation or with an alternative lens to control a size of the light distribution pattern to prevent spill over of light onto an adjacent passenger. The predetermined light distribution pattern may be circular. The adjustable aperture means may comprise a diaphragm which may be arranged to have a maximum radius that is selected such that there is little or no spill over of light in the predetermined light distribution pattern to an adjacent passenger space .

Reduced opening sizes narrow the size of the predetermined light distribution pattern. As before the diaphragm may be continuously adjustable or may be adjustable between predetermined opening sizes. Preferably the aperture means can be locked in a desired position.

Desirably the aperture means is provided adjacent the lens. The lens may be a standard lens since the predetermined light distribution pattern is selected by means of controlling the size of the opening in the diaphragm.

In one example the lens comprises at least a first lenticular lens and a second lenticular lens. In a preferred example the lens comprises a first lenticular lens having an array arranged in a first direction and a second lenticular lens having an array orientated at an angle to the first array. The lens may preferably be arranged such that the second lenticular array is orientated perpendicular to the first lenticular array. In one example a mask may be provided. The mask may be provided between the first and the second lenticular lenses. In one example the mask is cruciform shaped.

Preferably the LED bulb is selected to provide a colour temperature of from 2000 kelvin to 10 000 kelvin and preferably from 3000 kelvin to 7000 kelvin and more preferably from 3500 kelvin to 5000 kelvin or most preferably from 3500 kelvin to 4200 kelvin.

In a preferred example the cassette has a tamper proof connection to the reading light unit which in one example is in the form of removable mounting pins.

In one example the electrical connector comprises a dummy bayonet fitting. The electrical connector may comprise at least partially an open channel and an exit such that air can pass through the connector. The electrical connector may comprise self- sprung clips.

In one example the LED light assembly is arranged such that air can flow into and through the assembly comprises a number of apertures in at least an outer part of the cassette and a relative arrangement of the apertures is such that air is drawn into the cassette and over the printed circuit board. In a preferred example the apertures are formed by the removal of at least a portion of the plastic parts of the assembly and wherein at least 5% of an area of a plastic part is removed. In some examples the openings may be provided in the frame of surrounding the lens and optionally in the printed circuit board. The invention will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 is a cross sectional view of a reading light assembly incorporating an LED lighting assembly in accordance with the invention;

Figure 2 is a schematic diagram of a side view of an LED reading light design defining a passenger space;

Figure 3 is a top view of the LED reading light design of Figure 2,

Figure 4 is a section of the lens of the reading light of Figure 1 ;

Figure 5 is a perspective view of an LED lighting assembly in accordance with the invention;

Figure 6 is side view of the LED lighting assembly of Figure 5 ; Figure 7 is a cross section along the lines Q_Q of Figure 6, Figure 8 is a cross section of a prior art reading light unit;

Figure 9 is a schematic cross section of a side view of an alternative embodiment; Figure 10 is a front view of the LED lighting assembly of Figure 9;

Figure 11 is a perspective view of an electrical connector; and Figure 12 illustrates an adjustable aperture provided by a diaphragm. Figure 1 shows an LED lighting assembly 1 comprising a cassette 2 having a lens 4, a printed circuit board 6 on which is mounted an LED bulb 8. The cassette 2 has the lens 4 located at a front surface of the cassette and mounted within a frame 10. The cassette has side walls 12 which are provided with grooves 14 arranged to be able to mount with the printed circuit board 6. Outwardly extending tabs 15 cooperate with recesses 16 in a reading light unit 18 of a passenger service unit (not shown) in an aeroplane . The frame 10 and the side walls 12 of the cassette are connected together, the frame 10 clipping over the side walls 12. The frame is able to move relative to the side walls.

The printed circuit board 6 is secured to the side wall 12 of the cassette and is retained in place in use by retainer 100. The LED light bulb 8 is mounted on a front facing surface 20 of the circuit board 6. The circuit board 6 also has the necessary controls to operate the LED light bulb 8 as desired.

An optic 22 is provided which is mounted on the printed circuit board 6 surrounding the LED light bulb 8 and extending forwardly so enabling the light distribution pattern to be more accurately controlled. An electrical conductor 24 is mounted to the printed circuit board 6 and has a dummy bayonet cap 28 at a distal end of the connector 24 and the dummy bayonet cap is arranged to be able to connect to a standard bulb holder 30 of the reading light assembly. The electrical connector 24 can connect to a halogen bulb holder connector 30 and so provide a power supply 32 connection to the LED lighting assembly without the need to change the existing power supply or wiring.

The cassette 2 is shaped to be able to be fitted to existing halogen lighting housing 34 of the reading light unit in a passenger service unit 36. The lens 4 is transparent and is configured to deliver a predetermined light distribution pattern 38. The configuration of the lens 4 is selected to provide the desired light distribution pattern.

An example of a light distribution pattern 38 is shown in Figures 2 and 3. In Figure 3 the selected distribution is a squircle and as can be seen the light is distributed in a single passenger space 40 with negligible stray light passing into adjacent passenger spaces.

A lens 4 that can be used to achieve the desired light distribution is illustrated in Figure 4 and will now be described in more detail. The lens 4 has an inner side 42 and an outer side 44. The lens comprises a first lenticular lens 46 having an array. An inner planar face 48 is adjacent the LED bulb and a second face 50 having a number of regularly spaced first lenticular cells 52 forming the array extend longitudinally along the second face 50.

A second lenticular lens 54 is positioned adjacent the second face . The second lenticular lens has a first planar face 56 positioned to be in contact with at least a portion of the second face 50 of the first lenticular lens which has an array of lenticular cells 52 thereon. An outer face 58 of the second lenticular lens 54 has a number of regularly spaced second lenticular cells 60 forming a second array and extending longitudinally along the outer face 44. The second lenticular cells 60 on the outer face 44 are orientated perpendicular to the first lenticular cells 52 on the second face 50. The orientation of the arrays of the two lenticular lens perpendicular to one another forms the defined light distribution pattern

A mask 62 is provided between the first and the second lenticular arrays. The mask 62 is generally cruciform shaped. It will be appreciated that the mask can be alternative shapes. The mask improves the light distribution in the selected light pattern distribution. In this case it has been found that the cross shaped mask evens a variation in the intensity of the light distribution so making the reading light more comfortable for the user. The mask is formed of a reflective material and a reverse side of the mask reflect light back towards the LED bulb and optic

Turning now to Figure 5 the details of the cassette can be seen more clearly. The cassette 2 has side walls 12 which have a series of grooves 14. The grooves locate the printed circuit board in the cassette. A number of grooves are provided so that the position of the printed circuit board relative to the lens can be adjusted. In some cases it is desirable to allow for some variation depending on the focal length of the lens. The grooves additionally allow for cooling of printed circuit board. The printed circuit board is retained in place by the clip in retainer 100. The tabs 15 are more clearly visible in Figure 5. Four tabs are provided equi-spaced around the perimeter if the cassette. The tabs 15 are arranged to cooperate with recesses 16 in the side wall of the reading light unit. Rotating the cassette a few degrees engages the tabs in the recesses and secures the cassette in position.

The frame is clipped over a lip 102 of the side wall of the cassette and serves to retain the lens 4 in position in front of the LED lamp. A central aperture 104 allows light to pass through the lens and the frame to the passenger seating area.

An advantage of the LED assembly is that the cassette can be fitted in place as will be described below and the side walls are fixed in place relative to the reading light unit. The frame is able to rotate relative to the side walls when the cassette has been installed in a reading light unit.

In use the LED light assembly can be used to retrofit an LED light in a reading light unit 200 in a passenger vehicle such as that shown in Figure 8 by removing an existing bulb 202. An initial step is to squeeze the sides of the ring 204 allowing the ring 204 to be removed from the reading light unit. The glass 206 can then be removed allowing access to the glass 208. The glass 208 and the glass securing ring 210 and mounting ring 212 are also removed. The bulb 214 can then be removed from a bulb holder 30.

The dummy connector 28 is then connected to the bulb holder 30 so connecting the LED light assembly to the power supply unit 218. Once this step has been completed the cassette is inserted into the reading light unit. Mounting pins are provided at points generally indicated at 1 16 and extend through the frame into the material of the side wall connecting the two parts together and preventing relative rotation. The cassette is secured in the reading light assembly by the tabs 15 which are rotated to be secured in the recesses 16 of the reading light unit. The mounting pins are removed and the frame is free to rotate relative to the side walls of the cassette so preventing the cassette from being removed from the reading light unit. Further modifications and embodiments will now be described. Figure 9 shows an alternative embodiment of an LED light assembly arranged to remove heat from the printed circuit board printed circuit board. The cassette 1000 comprises a printed circuit board 1002 on which is mounted an LED bulb 1004. A lens 1006 is located on a front surface. The cassette comprises side walls 1008. In this embodiment the side walls 1008 comprises a forward projecting rim 1010. Openings 1012 are provided in the forward projecting rim 1010. Further openings 1014 are provided in a support 1016 supporting the lens 1006. Additional openings 1018 are provided in the cassette around an outside of the housing. Additionally openings 1020 are provided around the printed circuit board 1002. It will be appreciated that as heat is generated in the printed circuit board cool air is drawn through the openings and flows through the LED light assembly and over the printed circuit board. The skilled person will appreciate that openings may additionally be provided in the printed circuit board in an alternative embodiment. Leads from the printed circuit board are connected to an electrical connector 1024.

Figure 10 is a front view of the LED light assembly in which the openings 1012 can be seen. The openings 1012 in the rim 1010 are off-set from openings 1014 in the support 1016 and from the openings 1020 around the printed circuit board.

Figure 1 1 illustrated in more detail an alternative dummy bayonet cap 1024. The dummy bayonet cap 1024 comprises spring loaded clips 1026 arranged around a central channel 1028 in fluid connection with an internal chamber 1030 of the LED light assembly. An upper opening 1032 allows air to exit from the central channel 1028. Air from the chamber 1030 is able to flow into the bayonet cap. It will be appreciated that as heat is generated in the printed circuit board 1002 the heated air can rise from the printed circuit board and move through the bayonet cap 1024 and exit from the LED light assembly. Cooler air can be drawn from below the reading light assembly through the openings 1012, 1014, 1018 and over the printed circuit board 1002.

It has been found that the arrangement of openings allows the printed circuit board 1022to be cooled in operation and so to increase the reliability of the printed circuit board 1022 and to increase the longevity of the LED light assembly. Figure 12 illustrates an adjustable aperture means in the form of a diaphragm 1034 that can be inserted into the LED light assembly. The diaphragm 1034 can be adjusted to vary a radius of an opening 1036 in the diaphragm. The diaphragm can be added to the LED light assembly either forward of or behind the lens 1006. A means (not shown) for controlling a size of the opening 1036 is provided in the LED light assembly is provided. The radius of the opening 1036 can be reduced as can be seem in image A or increased as can be seen in image C. The increased light passing through the aperture in C brightens the light in the light distribution pattern 38 (shown in Figure 2) and increases the size of a defined passenger space. When the radius has been reduced as can be seen in image A the total light passing through the aperture and into the passenger space is reduced and the size of the light distribution pattern 38 is reduced. A sense of privacy for each passenger can therefore be improved and there can be a further reduction in light spilling over to an adjacent passenger space. It will be appreciated that the diaphragm is used in conjunction with the lens in this example and a quadrilateral shaped distribution pattern is maintained. The diaphragm controls the total light passing through the aperture and thus controls a size of light distribution pattern created at a set distance. The aperture can be adjusted to allow the size of the light distribution pattern to be adjusted at a particular distance from bulkhead to seat. It will also be appreciated that the adjustable aperture means can be used alone and that the adjustable aperture can provide sufficient control of the size of the light distribution pattern to prevent light from spilling over into an adjacent passenger space particularly when the radius of the opening in the diaphragm is reduced.