FIELD OF THE INVENTION

The present invention generally relates to methods for gradually brightening or dimming the brightness of one or more light emitting diodes, in particular methods of dawn simulation, methods of dusk simulation, dawn simulators, dusk simulators and light therapy devices, and methods of providing a substantially continuous brightness sweep of an LED(s). The invention further relates to a method of adjusting emission light colour of a light source, a light source having adjustable emission light colour, and an aromatherapy unit.

BACKGROUND TO THE INVENTION

A device known as a dawn simulator, otherwise known as a wake-up light, may provide dusk simulation and/or dawn simulation; for example, a dawn simulator may provide both a dusk simulation to help a user to fall asleep and a dawn simulation to help a user to wake up gently. Dawn simulation generally provides a gradually increasing light level in order to gently awaken a user, in a manner akin to the increase in light level of a natural dawn prior to sun rise. Similarly, dusk simulation generally provides a gradually decreasing light level. In either case, the light output may be provided by an incandescent bulb or, for example for longer lifetime and/or higher energy efficiency, light emitting diodes (LEDs).

For dawn simulation, the light level from an LED may be controlled using a pulse width modulation (PWM) scheme, for example as shown in Figure 2(a). Such a scheme generally uses a fixed forward current (or voltage) and the LED is switched on and off using a variable duty cycle (or duty factor - DF) to increase the average LED current and thus light output. However, difficulties remain in mimicking a natural gradual brightening and/or dimming of dawn and/or dusk for example with accuracy approaching or better than that achievable using an incandescent bulb.

Thus, the field of dawn simulators continues to provide a need for improvements such as, inter alia, accuracy of dawn and/or dusk simulation. Similarly, the fields of LED light control and light therapy continue to provide a need for, e.g., smoother brightening and/or dimming.

For use in understanding the present invention, the following disclosures are referred to:

- US patent application US2012019160, "Light emitting diode driving method and driving circuit", published Jan 26, 2012;

- US patent application US2012223648 "Adaptive Switch Mode LED System", published September 6, 2012;

- International patent application WO2012117403 "Improved phase controlled dimming LED driver system and method thereof, published September 7, 2012;

- Taiwanese patent application TW201223327 "Driving device and method for light emitting diode array", published June 1 , 2012;

- US patent application US2012062133 "Low voltage LED dimmer with integrated universal switch mode power supply", published March 15, 2012; and

- US patent application US2012181940 "Dimming of LED driver", published July 2012.

SUMMARY

According to a first aspect of the present invention, there is provided a method of dawn simulation using at least one light emitting diode (LED), the method comprising a plurality of iterations of pulse width modulating a drive signal to an LED, an initial one of the iterations to increase brightness of the LED from zero and followed by at least one further said iteration, wherein each of the iterations comprises: increasing duty cycle of the drive signal from a start duty cycle to an end duty cycle, wherein the start duty cycle and a start amplitude of the drive signal provide a start brightness of the iteration and the end duty cycle and an end amplitude of the drive signal provide an end, higher brightness of the iteration, wherein the start amplitude of a said further iteration is higher than the start amplitude of an immediately preceding one of the iterations, and a product of the start duty cycle and the start amplitude of the further iteration is equal to a product of the end duty cycle and the end amplitude of the immediately preceding iteration. The duty cycle (wherein 'duty cycle' and 'duty factor' are used interchangeably through this specification) and amplitude control applied in each iteration may be applied to provide a drive signal to a single LED, e.g. conventional semiconductor LED, or organic light-emitting diode (OLED), or to provide a substantially identical drive signal to each of a plurality of such LEDs (optionally coupled in parallel) at the same time.

By providing that, for any one or more of the further iteration(s), the product of the start duty cycle and the start amplitude of each of one or more further iterations is equal to a product of the end duty cycle and the end amplitude of the immediately preceding iteration, the start brightness level of each further iteration may be equal to the end brightness level of an immediately preceding iteration. When the product is increased for each further iteration relative to the preceding iteration, a steady increase in brightness may be achieved. Preferably, the amplitude is changed discontinuously at the boundaries between each iteration as is the PWM duty factor (DF) but the combination results in a seamless transition at each boundary. Advantageously, thus, the plurality of iterations may increase brightness of the LED from zero (wherein the LED is off, i.e., no light is being emitted) to the end brightness of the last one of the iterations substantially smoothly with substantially no perceptible discontinuity to a person observing the increasing brightness.

In such an embodiment, the initial iteration may be thus followed by one or a succession of two or more further iterations, wherein in the or each further iteration the amplitude preferably starts at a higher level than the level at the end of the immediately preceding iteration, and wherein in each further iteration a pulse width modulation duty factor preferably starts at a lower factor than that at the end of the immediately preceding iteration and gradually increases through the iteration. The increased duty factor of pulse width modulating of at least one iteration may increase the duty factor of the drive signal to an end duty factor of substantially (e.g., exactly) 100% during any one or more of the iterations.

The increase of duty cycle during an iteration is preferably gradual, e.g., may be stepwise, taking into account for example digital control. A current or voltage drive signal to one or more LEDs of an embodiment may thus have stepwise duty factor increases over a number of PWM periods of an iteration to achieve a gradual increase in duty factor (DF). Preferably, such stepwise duty cycle control provides a series of relatively small (preferably substantially imperceptible to a person observing the brightness) step increases in brightness, the step sizes preferably being substantially (e.g., exactly, perfectly) constant and/or following a brightness profile similar to that of a natural dawn.

By allowing the current the LED(s) to be increased from zero by gradually increasing the PWM drive signal duty factor, advantageously while keeping the amplitude low (e.g., below or not far above a nominal threshold turn-on voltage of the LED(s) (for an LED the threshold is related to the bandgap energy via eV=hcA,); preferably considerably lower than the rated maximum voltage or current applicable to the LED(s)) during at least the first iteration(s), e.g., just the initial iteration, an initial current may be delivered in the drive signal of an embodiment such that when the LED does turn on, i.e., begins to emit light, it does so when the drive amplitude is still relatively low, thus reducing or avoiding any abrupt increase in brightness.

Such an embodiment may provide a smooth brightness sweep of the LED from zero with substantially no perceptible brightness discontinuity to a person observing the sweep. This may mimic the gradual brightening effect of dawn more accurately, and preferably without abruptly disturbing a user observing the simulation, or a user who may be asleep or gently awakening.

At least one, e.g., every, iteration may comprise controlling the drive signal to have constant amplitude throughout the pulse width modulation iteration. Thus, for example the start and end amplitudes of any one iteration may be equal.

The initial iteration may comprise driving only the least significant bit (LSB), or alternatively at least lowest or close-to-lowest available levels, e.g., the first 2, 3, 4 or 5 lowest significant bits, of a digital output active (e.g., high, or digital ) to thereby set the drive signal amplitude at the start amplitude (and/or further amplitudes, e.g., end amplitude) of the initial iteration. Thus, a good resolution digital output may be exploited to assist smoothly turning on and/or smoothly increasing the brightness of the LED(s). The digital output for controlling the amplitude of the drive signal may have, e.g., 6- to 8-bit resolution in an embodiment.

All bits of such a digital output may be driven active to thereby set the drive signal amplitude at the start and/or end amplitude of at least the last one of the iterations, e.g., the last iteration. (A parallel bus configuration may be used (one output line for every bit); however this may not be the case). Additionally or alternatively, the start and/or end amplitude of at least the last one of the iterations may be substantially a maximum current rating of the LED.

According to a second aspect of the present invention, there is provided a method of dusk simulation using at least one light emitting diode (LED), the method comprising: a plurality of iterations of pulse width modulating a drive signal to an LED, the last one of the iterations to decrease brightness of the LED to zero and preceded by at least one further said iteration, wherein each of the iterations comprises: decreasing duty cycle of the drive signal from a start duty cycle to an end duty cycle, wherein the start duty cycle and a start amplitude of the drive signal provide a start brightness of the iteration and the end duty cycle and an end amplitude of the drive signal provide an end, lower brightness of the iteration, wherein the start amplitude of a said further iteration is lower than the start amplitude of an immediately preceding one of the iterations, and a product of the start duty cycle and the start amplitude of the further iteration is equal to a product of the end duty cycle and the end amplitude of the immediately preceding iteration.

Optional features may apply in an embodiment of this method correspondingly as for the method of dawn simulation, taking into account the decreasing brightness of dusk simulation as opposed to the increasing brightness of dawn simulation. Thus, the product of [amplitude * duty factor] and thus brightness is again preferably kept constant between adjacent PWM periods at boundaries between two successive iterations, and/or the initial iteration may be followed by one or a succession of two or more further iterations, wherein in the or each further iteration the amplitude starts at a lower level than the level at the end of the previous iteration (optionally remaining constant throughout the iteration) and in each iteration a pulse width modulation duty cycle gradually decreases. Similarly as for the first aspect, the duty cycle and amplitude control applied in each iteration may be applied to provide a substantially identical drive signal to each of a plurality of LEDs at the same time. The decreasing of duty cycle during an iteration is preferably gradual, e.g., may be stepwise taking into account for example digital control. A current or voltage drive signal of an embodiment may have stepwise duty cycle decreases over a number of PWM periods of an iteration to achieve a gradual decrease in duty cycle. Preferably, such stepwise duty cycle control provides a corresponding series of relatively small (preferably substantially imperceptible to a person observing the brightness) step decreases in brightness, the step sizes preferably being substantially constant and/or following a brightness profile similar to that of a natural dusk.

Advantageously, an embodiment of the second aspect may provide a smooth brightness sweep of an LED from the start brightness of the initial iteration to zero brightness, with substantially smoothly, e.g., with no perceptible brightness discontinuity to a person observing the sweep. This may mimic the gradual dimming effect of dusk more accurately, and preferably without abruptly disturbing a user observing the sweep (or a user who may have fallen or be falling asleep).

According to a third aspect of the present invention, there is provided a dawn simulator comprising at least one light emitting diode (LED), the dawn simulator having: a drive source to provide a drive signal for driving the LED; a drive controller to provide a drive control signal; an amplitude control circuit configured to control an amplitude of the drive control signal according to the drive control signal; a modulator controller to provide a duty cycle control signal; and a pulse width modulation circuit configured to control a duty cycle of the drive signal according to the duty cycle control signal, wherein the modulator controller is configured to control the pulse width modulation circuit to perform a plurality of iterations of pulse width modulating the drive signal, an initial said iteration to increase brightness of the LED from zero, the iterations comprising at least one further said iteration, the modulator controller configured such that each of the iterations comprises increasing duty cycle of the drive signal from a start duty cycle to an end duty cycle, wherein the start duty cycle and a start amplitude of the drive signal provide a start brightness of the iteration and the end duty cycle and an end amplitude of the drive signal provide an end, higher brightness of the iteration, the drive controller configured to control the amplitude control circuit such that the start amplitude of a said further iteration is higher than the start amplitude of an immediately preceding one of the iterations, the drive controller and modulator controller configured such that a product of the start duty cycle and the start amplitude of the further iteration is equal to a product of the end duty cycle and the end amplitude of the immediately preceding iteration.

The dawn simulator may implement optional features as set out above for the method of the first aspect. For example, constant [amplitude * duty cycle] product between adjacent PWM periods at a boundary between iterations may reduce and/or avoid any change in brightness between the iterations. Similarly, the increase in duty cycle in an iteration is preferably gradual and may be stepwise. The dawn simulator is advantageously configured to provide a smooth brightness sweep of the LED with substantially no perceptible brightness discontinuity to a person observing the sweep.

An embodiment of such a dawn simulator may control the drive level, e.g., current or voltage amplitude of the drive signal. The drive signal is preferably a current signal, albeit optionally determined by a controllable voltage source output in an embodiment. Thus, the drive source is preferably a controllable voltage source resulting in variable current to the LED. Such a source may be implemented using a digital potentiometer or a digital to analogue converter (DAC) to control a voltage regulator.

An embodiment may be arranged such that the amplitude control is applied to a drive signal then passed to the pulse modulation circuit, or conversely the PWM may be applied to a drive signal then passed to the amplitude control circuit. Alternatively, the PWM and amplitude control may be combined to provide a single signal re-shaping process applied to the drive signal. Regardless, the PWM and/or amplitude control may be applied at source, i.e.., the drive source may comprise the pulse width modulation circuit and/or the amplitude control circuit, and/or the PWM modulation and/or amplitude control circuits do not receive the drive signal but form part of a drive signal generator. Thus, the drive signal may be generated with the desired PWM and/or amplitude modulation, rather than such modulation being applied to a previously generated, e.g., constant amplitude, drive signal.

According to a fourth aspect of the present invention, there is provided a dusk simulator comprising at least one light emitting diode (LED), the dusk simulator having: a drive source to provide a drive signal for driving the LED; a drive controller to provide a drive control signal; an amplitude control circuit configured to control an amplitude of the drive control signal according to the drive control signal; a modulator controller to provide a duty cycle control signal; and a pulse width modulation circuit configured to control a duty cycle of the drive signal according to the duty cycle control signal, wherein the modulator controller is configured to control the pulse width modulation circuit to perform a plurality of iterations of pulse width modulating the drive signal, a last said iteration to decrease brightness of the LED to zero, the iterations comprising at least one further said iteration, the modulator controller configured such that each of the iterations comprises decreasing duty cycle of the drive signal from a start duty cycle to an end duty cycle, wherein the start duty cycle and a start amplitude of the drive signal provide a start brightness of the iteration and the end duty cycle and an end amplitude of the drive signal provide an end, lower brightness of the iteration, the drive controller configured to control the amplitude control circuit such that the start amplitude of a said further iteration is lower than the start amplitude of an immediately preceding one of the iterations, the drive controller and modulator controller configured such that a product of the start duty cycle and the start amplitude of the further iteration is equal to a product of the end duty cycle and the end amplitude of the immediately preceding iteration.

The dusk simulator may implement optional features as set out above for the method of the second aspect.

According to a fifth aspect of the present invention, there is provided a light therapy device having at least one light emitting diode (LED) and comprising: a drive source to provide a drive signal for driving the LED; a drive controller to provide a drive control signal; an amplitude control circuit configured to control an amplitude of the drive control signal according to the drive control signal; a modulator controller to provide a duty cycle control signal; and a pulse width modulation circuit configured to control a duty cycle of the drive signal according to the duty cycle control signal, wherein the modulator controller is configured to control the pulse width modulation circuit to perform a plurality of iterations of pulse width modulating the drive signal, an initial said iteration to increase brightness of the LED from zero, the iterations comprising at least one further said iteration, the modulator controller configured such that each of the iterations comprises increasing duty cycle of the drive signal from a start duty cycle to an end duty cycle, wherein the start duty cycle and a start amplitude of the drive signal provide a start brightness of the iteration and the end duty cycle and an end amplitude of the drive signal provide an end, higher brightness of the iteration, the drive controller configured to control the amplitude control circuit such that the start amplitude of a said further iteration is higher than the start amplitude of an immediately preceding one of the iterations, the drive controller and modulator controller configured such that a product of the start duty cycle and the start amplitude of the further iteration is equal to a product of the end duty cycle and the end amplitude of the immediately preceding iteration. Similarly as for the third aspect, the light therapy device may be configured to implement optional features as set out for the method of the first aspect. Such a light therapy device may for example be for treatment of SAD (Seasonal Affective Disorder), skincare, (e.g., acne) or treatment of allergic reactions (e.g., hay fever).

According to a sixth aspect of the present invention, there is provided a method of providing a substantially smooth brightness sweep of an LED from substantially zero brightness to substantially a maximum brightness of the LED, the method comprising: a plurality of iterations of pulse width modulating a drive signal to an LED, an initial one of the iterations to increase brightness of the LED from zero and followed by at least one further said iteration, wherein each of the iterations comprises: increasing duty cycle of the drive signal from a start duty cycle to an end duty cycle, wherein the start duty cycle and a start amplitude of the drive signal provide a start brightness of the iteration and the end duty cycle and an end amplitude of the drive signal provide an end, higher brightness of the iteration, wherein the start amplitude of a said further iteration is higher than the start amplitude of an immediately preceding one of the iterations, and a product of the start duty cycle and the start amplitude of the further iteration is equal to a product of the end duty cycle and the end amplitude of the immediately preceding iteration.

Such a sweep may be advantageous for example for general space lighting, e.g. a mood lighting device, that lights up gradually preferably with gradual colour change (e.g., the method being applied to control each LED of a plurality of lights having different colours, to thus smoothly vary the combined light output colour and/or intensity).

According to a seventh aspect of the present invention, there is provided a method of dawn simulation using at least one light emitting diode (LED), the method comprising: pulse width modulating a drive signal to an LED, wherein said pulse width modulating gradually increases a duty cycle of said drive signal to thereby increase the brightness of an LED from zero to a first brightness level, wherein an amplitude of said drive signal does not exceed a predetermined first level during said gradual increase; and then gradually increasing an amplitude of said drive signal from said first level to a second, higher level to provide a second, higher brightness level of said LED. The increasing the brightness from zero to a first brightness level is preferably followed by said gradually increasing the amplitude of said drive signal to said second, higher level, such that brightness of the LED increases from zero to said second, higher brightness level substantially smoothly with substantially no perceptible discontinuity.

In any of the above methods, each LED may be a white LED, the method comprising outputting light from the at least one LED through a filter. The filter is preferably orangey. The filter preferably has maximum peak transmittance at a wavelength between 590-620nm. In another embodiment the filter may have a reduced or minimum transmittance at a wavelength between 450 nm and 530 nm. Either example may concern a filter characteristic across the spectrum of a white light LED and/or visible wavelengths of 390nm to 700nm.

In any of the above methods, the at least one LED may comprise different colour LEDs and the method varies the overall output colour during the dawn simulation by controlling respective power outputs of the different colour LEDs.

According to a further aspect of the present invention, there is provided a method of adjusting emission light colour of a light source, the light source comprising at least two pluralities of light emitting diodes (LEDs), the pluralities comprising a first said plurality and a second said plurality, wherein LEDs of said first plurality are interlaced with LEDs of at least the second of the at least two pluralities, the method comprising: transmitting light from the first plurality of LEDs through first diffuser elements; transmitting light from the second plurality of LEDs through second diffuser elements, wherein a transmission spectrum of the first diffuser elements is different to a transmission spectrum of the second diffuser elements, the method comprising varying relative light power output of at least the first and second pluralities of LEDs to thereby control an overall colour of light output from the light source.

Such a method may allow relatively inexpensive control of colour and/or colour temperature. Different colours and/or colour temperatures to be achieved simply by brightening certain LEDs which have different colours of diffusion above them. Blue light may be selected without needing to have it permanently. Mixing of colours from single colour LEDs rather than using different colour LEDs may be achievable, for example if all of the LEDs are white and the first diffuser elements are coloured to block blue light, e.g., 450-495nnm wavelength light, to a greater extent than the second diffuser elements (which may be fully transmissive), the white LEDs under the second diffuser elements may be turned on later and/or more gradually than the white LEDs under the first diffuser elements, preferably to give the impression of increasing daylight. The opposite process may occur for dusk. Additionally or alternatively, if all of the LEDs are white and the first diffuser elements have peak transmission of orangey and/or reddish light, e.g., any band of wavelengths within 590-750nm (e.g., 590-620nm and/or 620-750nm), the second diffuser elements for example having peak transmission outside this band and/or being fully transmissive, the white LEDs under the first diffuser elements may be turned on first and the white LEDs under the second diffuser elements turned on more gradually, and/or the first diffuser elements may be turned on first and gradually turned off while the white LEDs under the second diffuser elements are on, preferably to give the impression of increasing daylight. The opposite process may occur for dusk.

The interlacing may provide a chequerboard pattern for the LEDs and corresponding diffuser elements where there are two pluralities of LEDs. Where more than two banks of LEDs are provided the pattern may be more complex (e.g., ABCABCABC... across each row and down each column however the pattern preferably remains regular so provide a uniform colour of the light source when all LEDs are on.

There may further be provided the method of adjusting emission light colour of a light source, wherein at least the first diffuser elements filter light from the first plurality of LEDs and at least the second diffuser elements are substantially fully transmissive. Thus, the second diffuser elements may transmit greater than 95% or 99%, e.g., 100%, of light from the second LEDs. Preferably the colour of light transmitted through the second diffuser elements from the second LEDs is substantially unchanged by the second diffuser elements.

Additionally or alternatively, the diffuser elements for filtering light from one of the pluralities of LEDs may have a different 'colour' (spectral filter characteristic) relative to the diffuser elements for filtering light from another of the pluralities of LEDs. Any two or more such sets of diffuser elements may have different colours and/or any two or more of the pluralities of LEDs may have different colours. Preferably however all LEDs of all pluralities are nominally identical.

In such a method, the LEDs of the pluralities of LEDs may be white LEDs and the first diffuser elements may filter out blueish light from the first plurality of LEDs, the method comprising varying relative light power output of at least the first and second pluralities of LEDs to thereby control a proportion of blue light in an overall emission spectrum from the light source. Such filtered blue light may be, e.g., all light below 530nm, or may be light of 450-495nm.

In embodiments, at least two of the pluralities of LEDS may have different colours, for example to allow a manufacturer to achieve a preferred overall colour depending on spectral filtering characteristics of the diffuser elements.

There may further be provided the method of adjusting emission light colour of a light source, comprising a method of dawn simulation using at least one LED as defined above, wherein at least one of the first and second pluralities of LEDs comprise a said at least one LED, said relative varying light power output comprising controlling light output of each of the at least one LEDs by a said plurality of iterations of pulse width modulating a drive signal to the LED, the method of adjusting being used to adjust an overall colour of light output from the light source during said dawn simulation.

There may further be provided the method of adjusting emission light colour of a light source, comprising a method of dusk simulation using at least one LED as defined above, wherein at least one of the first and second pluralities of LEDs comprise a said at least one LED, said relative varying light power output comprising controlling light output of each of the at least one LEDs by a said plurality of iterations of pulse width modulating a drive signal to the LED, the method of adjusting being used to adjust an overall colour of light output from the light source during said dusk simulation.

According to a further aspect of the present invention, there is provided a light source having adjustable emission light colour, the light source comprising at least two pluralities of light emitting diodes (LEDs), the pluralities comprising a first said plurality and a second said plurality , wherein LEDs of said first plurality are interlaced with LEDs of at least the second of the at least two pluralities, the light source further comprising: first diffuser elements configured to transmit light from the first plurality of LEDs; second diffuser elements configured to transmit light from the second plurality of LEDs; at least two drivers to control output light power of respective ones of at least the first and second pluralities of LEDs, wherein a transmission spectrum of the first diffuser elements is different to a transmission spectrum of the second diffuser elements, the drivers configured to vary light power output of at least the first plurality of LEDs relative to light power output of the second plurality of LEDs to thereby control an overall colour of light output from the light source.

There may further be provided the light source, wherein at least the first diffuser elements filter light from the first plurality of LEDs and at least the second diffuser elements are substantially fully transmissive.

There may further be provided an above defined dawn simulator comprising the light source, wherein at least one LED of the pluralities of LEDs of the light source comprises a said LED of the dawn simulator.

There may further be provided an above defined dusk simulator comprising the light source, wherein at least one LED of the pluralities of LEDs of the light source comprises a said LED of the dusk simulator.

An aromatherapy unit may comprise any of the above apparatus, e.g., at least one of the above defined dawn simulator, light therapy device; dusk simulator or light source.

Preferred embodiments are defined in the appended dependent claims.

It is further noted that any one or more references to 'dawn' above and below may be substituted with "dawn and/or sunrise" for alternative arrangements and/or processes, and similarly 'dusk' with "dusk and/or sunset". Similarly, the fifth aspect may similarly be used for simulating dusk, dawn, sunset and/or sunrise.

Further still, any one or more of the above aspects and/or any one or more of the above optional features of the preferred embodiments may be combined, in any permutation.

BRIEF DESCRIPTION OF THE DRAWINGS

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

Figs. 1 (a) and (b )show, respectively : (a) an example forward current versus forward voltage characteristic for an LED; and (b) an example relative luminous flux versus forward current characteristic for an LED;

Figs. 2(a) and (b) show example pulse width modulation (PWM) schemes, wherein l _max may be the rated maximum for the LED;

Fig. 3 shows an example block diagram of a dawn simulator, light therapy device or space lighting device implementing a LED drive scheme embodiment;

Fig. 4 shows a PWM scheme of an embodiment;

Fig. 5 shows a drive scheme of a preferred embodiment, showing LED emission intensity on the y-axis and average drive voltage (or current) on the x-axis, the characteristic having regions 1 - 5;

Fig. 6 shows drive characteristics for: (a) a brightening sweep; and (b) a dimming sweep. Specifically, Fig. 6 (a) shows a drive signal variation of one embodiment, through an initial region from zero with pulses of constant low amplitude but increasing duty cycle and through a subsequent, further region (right hand side of vertical dividing line of Fig. 6(a)) with higher amplitude and increasing duty cycle. It is noted that Figs. 6(a) and (b) are merely illustrative and are thus not to scale. Furthermore, Figs. 6(a) and (b) may not show the exact number of pulses of any region(s) of a particular embodiment, and may be considered complete or partial, e.g., partial in that there may be one or more further regions in an embodiment, i.e., more regions than the two shown in each of Figs, (a) and (b); Fig. 7 is a schematic diagram of an aromatherapy unit.

Fig. 8 shows a cross section showing the internal structure of the aromatherapy mechanism.

Fig. 9 shows an example optical stack comprising a staggered diffuser.

Fig. 10 shows a staggered diffuser filter pattern. A corresponding pattern of LEDs from bank 1 (B1) and bank 2 (B2) may be arranged in a two-dimensional matrix, looking perpendicular to the surface. Such a pattern is suitable for the diffuser arrangement of Fig. 9.

Fig. 11 shows an LED control scheme with two LED banks for the diffuser arrangement of Fig. 9; on a printed circuit board, the LEDs from two banks may be interlaced, rather than grouped, across the entire available real estate.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

An embodiment provides a drive scheme for fine control of light emitting diode (LED) light level. Such a scheme may be advantageous for controlling LED light at the very low output levels required to mimic the beginning of dawn, and/or the operation of an incandescent bulb at the beginning of a dawn simulation. Preferably, the embodiment provides a continuous brightness sweep with substantially no perceptible brightness discontinuity.

In this regard, the inventors have realised for example that, under conventional digital duty cycle control, the first few bits of control may not result in any observable light output, then for the n-th control value, e.g., n~5, there is a discontinuous step in light level. In contrast, an embodiment may mimic the gradual brightening effect of the sun more accurately, e.g., without such a discontinuity that may abruptly awaken the user.

In this regard, Fig. 2(b) shows the general function of an LED Pulse Width Modulation (PWM) driver to modulate the forward current of the LED in a PWM scheme. The current is modulated from zero to the maximum driven forward current l _max in pulses of width, t, occurring every T seconds (T=1/f where f is the modulation frequency). The modulation level is defined as t/T; when t=T the modulation level (or duty factor) is 100%. Typically, the increment in t (At )is given by At=T/(2 -1) where N is the resolution of the PWM drive (e.g., 6, 8, 10-bit, etc).

For LEDs, the maximum driven current, l _max , of such PWM control may be chosen to be within the specified rating of the LED (e.g., 20mA). To control the light intensity the PWM scheme is used to vary the average current, l _ave from zero to l _max , where l _ave = t/T*l _max . This variation in l _ave results in an observable change in the light intensity which is acceptable for most applications.

When this scheme is used to drive LEDs at very low l _ave however, it is observed that the first few levels of the PWM drive, as described above, do not result in a perceptible light intensity. As l _ave is increased to the next level a comparatively high light intensity is observed. This perceptible jump in light intensity is undesirable in dawn simulators since some people are very sensitive to discontinuous changes in light level.

In order to obtain the desired effect of a continuous increase in light intensity from zero, such a drive scheme may be modified so that the maximum driven current, l _max (e.g., set by a signal from a feedback resistor), is varied additionally to the duty factor. Initially, l _max is set at, say, 1/64 of the maximum rated current (0,3125mA for 20mA maximum rated current) (preferably a digital potentiometer which controls the output is set at the minimum value; this would be 1/64 of the maximum for a 6-bit pot). The value of lmax is that which corresponds to this minimum pot value) then the PWM drive is applied from 0 to 100% of this value. This may provide a resultant low level of light which is perceived to have varied continuously from zero. After this, the value of l _max may be varied from 1/64th to 100% of the maximum rated current whilst keeping the PWM drive at 100% duty factor (again, 1/64th being indicated for a 6-bit pot, however an alternative resolution pot with different minimum value could be used), alternatively a further iteration of applying PWM drive from 0 to 100% may be carried out with higher constant, or increasing, current. In this way the perceived light level may be varied quasi-continuously from zero to maximum corresponding to a variation in average drive current from zero to the final l _max.

A preferred embodiment utilizes the LED characteristics such as those of Figures 1 (a) and 1 (b), in combination with PWM control. In contrast to Fig. 2(a) or (b), a variable forward current (or voltage) may be used and the LED switched on and off, e.g., between 0 and 100% duty factor (0% for t=0; 100% for t=T). Under microprocessor control with N bits resolution, t can takes values t = nT/(2 -1) where n = 0,1 ,2 ... 2 ^N -1 . For example, N is 8, 12 or 16 bits. In such a scheme, the first few bits of control may allow an observable light output and/or substantially no discontinuous step in light level may be observed as the value represented by the bits increases. Thus, the gradual brightening effect of an incandescent bulb may be mimicked more accurately and/or without abruptly wakening the user.

Thus, in order to obviate the discontinuous step, an embodiment additionally controls the forward LED current (or forward voltage). In effect, the driven current l _max is not fixed but varied from a low value up to, e.g., the maximum rated value for the LED and the PWM drive is made to operate with a wide range of current (or voltage) values.

An example system block diagram is shown in Figure 3, wherein an amplitude controlled drive signal LED_Fwdvolts is pulse width modulated to drive one or more LEDs. Thus, a variable current (or voltage) is input into the PWM drive. Thus, the Fig. 3 embodiment generally applies a PWM driver on top of a variable amplitude source. In this case, the PWM driver may be considered as being primary, and the variable amplitude part, secondary. This may be preferred, in light of availability of PWM drivers either as discrete devices or as functions within microcontrollers whereas variable voltage devices and schemes are less commonplace. However, in general terms one could have either as the primary.

An embodiment such as that shown in Fig. 3 may use digital and/or analogue control. In particular, neither of the PWM driver and variable amplitude source needs to be digital, i.e., either or both may be analogue. Advantage(s) such as providing the LED brightening/dimming scheme in LED-based dawn simulators may be achieved whether the PWM and/or amplitude variation is done by analogue or digital means. Nevertheless, merely by way of example, a primarily digital implementation is discussed below.

Generally, Fig. 3 for dusk and/or dawn simulation shows a drive source Vin, a drive controller 2 (labelled for example as 0-63 (6-bit) voltage levels; alternatively the voltage levels may be 1-64) to provide a digital output as a drive control signal, an amplitude control circuit 1 (described for example as Variable voltage control LED Vf or Variable voltage control LED_FwdVolts) to control the drive signal amplitude according to the drive control signal, a modulator controller 4 (for example PWM Drive 0 - 100% duty factor) to provide a duty cycle control signal, a pulse width modulation circuit 3 (described for example as a LED PWM Drive Circuit) to modulate the amplitude controlled drive signal according to the duty cycle control signal, and LEDs D1 - Dx (there may be more or less than four in an embodiment). In one implementation, increases in amplitudes of the drive signal, for example within a PWM iteration and/or at a boundary between such iterations, are fractions of a final maximum drive current (voltage) l _max (V _max ), e.g., the first input current or voltage after zero in an initial iteration may be, say, \ _ma> J63 or V _max /63 (or \ _ma> J64 or V _max /64), and/or the amplitude of such an iteration may be up to (preferably gradually increasing to) an amplitude of, e.g., 5*l _max /63 or 5*V _max /63 (or 5*l _max /64 or 5*V _max /64) (similarly as above, an alternative resolution pot with different minimum value could be used thus a denominator other than 63 or 64 may be appropriate), while the PWM drive operates on top of this according to Figure 2(a) to eventually achieve an [end amplitude * DF] product, or end brightness, of the iteration. An end amplitude of a (preferably final) PWM iteration may be, e.g., I _max or V _max ; this may be the rated current/voltage for the LED. Overall control of the units 1 - 4 may be provided by a central controller such as a microprocessor.

Thus, preferably, the input current is increased according to a predetermined scheme and the PWM drive operated on top of this also according to a predetermined scheme. A net effect of this may be an ability to drive the LED(s) such that visually near-continuous variation in light flux is possible from very low levels to the maximum rated flux and vice versa.

An embodiment may thus reduce or avoid a discontinuity that may otherwise be caused by the first few levels of the PWM being used up in filling reactive components of the LED and/or drive circuitry and not contributing to perceptible light emission and the next PWM level then resulting in a higher-than-desired light intensity which jumps from zero. Rather, the maximum current in an embodiment may initially be a much lower value than the maximum rated current (for the LED) and the PWM drive may then be applied at this reduced current. An effect of this is may be to turn the LED(s) on in a much more gradual fashion. Once the PWM drive reaches 100% duty factor at this reduced maximum current, the current may be increased in a stepwise fashion for the next iteration using, e.g., a digital to analogue converter (DAC) or programmable regulator, or a regulator controlled using a digital potentiometer. An example embodiment may use PWM to vary the average current from zero to an initial l _max of an iteration, then varying the maximum current, l _max , of the pulses, within or at the boundary with a subsequent varying PWM iteration. In an embodiment, this may have the advantage of driving the LEDs along their characteristic curve, negotiating the tricky 'knee' region of the forward current versus voltage LED In this regard, it is noted that light emission of an LED (semiconductor or organic) is proportional to current. If the LED is modulated at a frequency much higher than the eye/brain can resolve then it is the average current which determines the light intensity characteristic.

In a specific example embodiment wherein a PWM scheme is used with the drive voltage (or current) being variable rather than fixed, e.g., the drive voltage/current increasing at boundary(s) between PWM iterations and/or gradually during one or more PWM iterations, one can set the drive parameter, i.e., amplitude, to V _max /N where V _max is here the maximum available signal amplitude and N may lie in the range 0-63 (or 1-64) using a 6-bit variable voltage (or current) source. For every value of N, the LED(s) can then be driven with the full PWM scheme. An example is shown by the drive versus time characteristic of Fig. 4, wherein DF indicates duty factor.

Additionally or alternatively, an embodiment may start with a low voltage, e.g., just below or about, e.g., about the knee voltage (-2.3V in Fig 1 (a)), e.g., 2.3V for white phosphor-clad LEDs (the actual value depending on the production spread of the LED's "Vf" characteristic) and apply, e.g., an 8-bit to 12-bit PWM drive to this. This will bring the LEDs up from zero emission to a low level. The voltage is then changed to a higher value and the LEDs driven from an intermediate duty factor such that the emission intensity is substantially seamless from one set of drive parameters to the next. And so on.

Fig. 5 shows such a scheme. As shown, in each region of this particular embodiment the drive level is substantially constant while the duty factor (DF; duty cycle) increases. The minimum number of regions is two (an initial region 1 followed by a further region 2), but a maximum may be determined by the number of amplitude control bits, e.g., 64 for 6bit. Preferably, the PWM drive for region(s) 2 and above (above if more than 2 regions) start with a non-zero duty factor (DF). This may be advantageous for allowing the interfaces between each of the drive regions to be seamless so that there is less / no flicker.

As indicated in Fig. 5, a seamlessness condition at a boundary between regions n and n+1 may in an embodiment be:

In this regard, it is noted that light emission of an LED (semiconductor or organic) is proportional to current. If the LED is modulated at a frequency much higher than the eye/brain can resolve then it is the average current which determines the light intensity. The above seamlessness condition is thus expressed in terms of the average current and duty factor on either side of the boundary, such that the light intensity is the same on either side of the boundary.

Example parameters for scheme having at least 5 regions are:

Region 1 : Vmax/63 x DF0 to DF1 PWM

Region 2: Vmax/16 x DF16/63 to DF1 PWM

Region 3: Vmax/8 x DF8/16 to DF1 PWM

Region 4: Vmax/2 x DF2/8 to DF1 PWM

Region 5: Vmax x DF1/2 to DF1 PWM

It is further noted that the actual number of drive regions is preferably kept to a low level, e.g., to reduce complexity - in practice an embodiment may not use every available bit from both the variable voltage (current) supply and the PWM driver. Thus, the number of amplitude levels and thus regions used in a scheme such as that of Fig 5 may be lower than that possible using the full resolution available, but preferably an embodiment will have more than two regions. For example, if there are 6 bits of amplitude resolution available and 8 bits of PWM resolution then the maximum possible resolution may be 14 bits; in practice there may be less than this but restricting the amplitude to two non-zero values may restrict the overall performance of the scheme by restriction of the available resolution. That said, regions 3 and beyond may effectively simply repeat the principle of the first two regions and, from a practical viewpoint for improved performance, e.g., accuracy, and generally speaking, the more bits (regions) the better.

Figs. 6(a) shows an example drive scheme (progression of drive level with time) for a brightening sweep, e.g., dawn simulation, wherein in the second, further region (beyond the illustrative vertical line at the end of the first, initial region) variable PWM may be applied with an increase in the drive level at the boundary between the regions. For dimming, e.g., dusk simulation, a reverse characteristic may be applied as shown in Fig. 6(b). In this regard, it is noted that either of the sweeps of Figs. 6(a) and (b) may comprise addition regions, e.g., 5 or more consistent with Fig. 5. However, when using full resolution of a digital output, e.g., a 6-bit output, for amplitude control along with the full resolution afforded by the PWM controller, a scheme such as that of Fig. 5 may be extended to have considerably more, e.g., 64, regions.

While the above has focussed on brightening, e.g., dawn simulation, it is noted that embodiments may be advantageous for dimming, e.g., dusk simulation. However, a dawn simulator performing both dawn and dusk simulation may use a conventional PWM control scheme for dusk simulation and an embodiment for dawn simulation.

The following describes an aromatherapy unit combinable with any of the above described features, embodiments and aspects. Any one or more features of such a unit may implement any of the herein describes methods for gradually brightening or dimming the brightness of one or more light emitting diodes, in particular methods of dawn simulation, methods of dusk simulation, dawn simulators, dusk simulators and light therapy devices, and methods of providing a substantially continuous brightness sweep of an LED(s).

Aromatherapy generally uses so-called "essential" oils in a way that promotes an improved the sense of well-being. The benefits of aromatherapy include aiding relaxation, relieving stress and boosting energy levels. Two basic mechanisms can explain the known effects of essential oils. One is the influence of aroma on the brain, especially the limbic system through the olfactory system. The other is the direct pharmacological effects of the "essential" oils. One embodiment of the aromatherapy unit combines a controlled light source with a traditional alarm feature to offer a gradual sunrise and sunset to aid maintenance of the user's circadian rhythm. In addition, an aromatherapy function is provided, which will complement the user experience during their wake up or going to sleep routine. Thus, such a unit may be considered a medical device.

In addition to a gradual sunrise/sunset, such a unit may offer two compartments for night time and wake time oils. The oils and aromas may be selected by the user to suit their personal needs for going to sleep with and waking up. To allow for specific scents during wake-up and sleep times, two separate aromatherapy chambers may be provided.

Regarding the dual aromatherapy sources, Fig. 7 shows a schematic representation of a unit with its main cover (diffuser) removed. Two independent aromatherapy sources are incorporated providing two different scents; one for the wake up and one for going to sleep routine.

During the wake up routine, a sunrise cycle may commence, e.g., 30 minutes (depending on user setting) prior to the alarm time, so that the maximum brightness is reached at the desired wake-up time, when an optional sound alarm is then triggered. The aromatherapy feature may also be activated prior to alarm time (duration and time of onset prior to the alarm time set by the user), so that the user will experience the desired scent in the room as well. A reverse experience can be activated at sunset.

The scent may be generated using a method of liquid atomisation where a reservoir containing water mixed with a small amount of essential oil is exposed to ultrasound energy source operating in the region between 1.7 MHz to 2.5 MHz. One aromatherapy chamber may be designated for sunrise, the other for sunset, for ease of use. Either chamber may be used for aromatherapy if the alarm is not set.

The two reservoirs may be removable from the main unit for the purposes of: user replacement in case of transducer failure; cleaning and/or maintenance; and/or refilling. Fig. 8 shows an example structure of the aromatherapy assembly. It can be seen that the ultrasound transducer is positioned in the base of the reservoir and set to project the ultrasound energy vertically and through the liquid contained within the said reservoir. Electrical connections from the transducer may be terminated to the 'male' part of the electrical connector and the corresponding 'female' part of the connector may be in the base of the reservoir cradle (not shown in this diagram). The connector arrangement may allow the whole assembly to be easily removed from the system.

Ultrasound transducers generally have a limited life (up to 10,000 hours) and it is therefore envisaged that they would need to be replaced at some point during the lifetime of the product. Rather than having to send the whole product back to the manufacturer, the removable reservoir assembly may be replaced instead, and the user would not be required to do any particular maintenance themselves. Each reservoir may be labelled to make them distinguishable once they are charged with particular scent.

A user interface for the unit may consist of a small oval LCD display having HxV resolution of 192 x 64 pixels and there may be 3 user keys on the front and/or below the display. In order to enhance the user experience during setup and direct control over certain key functions, an infra-red (IR) controller may also be included in the system. The Remote Controller may be used to program the settings and be able to control all functions other than, e.g., snooze and/or dimming the LCD display (which will be done using the buttons). As an alternative to the RC, or possibly as an additional feature alongside the RC, the buttons on the device may alternatively be soft controls so their function changes based on which context the user is in.

Considering lighting, a dawn/dusk simulation feature of the unit may offer sunrise and sunset features, preferably implemented by using LED rather than halogen or incandescent technology. Due to the complexity of combining two aromatherapy chambers and light in a single unit a quantity of low-powered LEDs of a single colour may be used, such that there would not be colour mixing, other than that the internal light source diffuser may be tinted to provide light of a pleasing spectrum. Additional colour mixing to provide sunrise simulation (e.g. starting with a very dim reddish light and ending with a bright white light) may however be a desirable additional feature. In an embodiment a staggered optical diffuser may be provided as further described herein for example to provide a desirable colour and/or colour temperature and/or reduce the amount of blue light emitted.

The driving scheme for the LEDs may involve a combination of pulse width modulation and amplitude modulation. The drive scheme may be as described herein for fine control of LED light level. As mentioned above, such a scheme may be advantageous for controlling LED light at the very low output levels required to mimic the beginning of dawn. Preferably, the unit may then provide a continuous brightness sweep with substantially no perceptible brightness discontinuity.

Any one or more of the following may be provided in the unit:

- user interface to set a variety of sunrise or sunset durations;

- a back-up beep to sound at the user's chosen wake-up time, and starting quietly and/or slowly, getting progressively louder and/or faster;

- additional wake-up or sleep sounds;

- mood lighting;

- the LCD display dimmable by the user or completely turned off at any time, or as part of the alarm setting; and/or

- aromatherapy settable as either continuous or intermittent.

Considering lighting for a dawn and/or dusk simulator and/or aromatherapy unit as discussed above, different approaches are envisaged for providing a desirable light colour. Such approaches may additionally or alternatively be used to substantially or completely block out blue light, e.g., towards bed time, when it can be alerting and prevent sleep.

A first approach may use white LEDs, and these can be harsh in colour. In order to arrive at a colour which is a pleasanter user experience an internal, e.g., orange, filter may be used. This may be preferable to the use of warm white LEDs where either the colour is unsatisfactory and/or the output lumens are lower. A second approach may be to use colour mixing of LEDs.

A further approach may be to have a diffuser which is coloured over some LEDs and not others, or to have different colours over different LEDs. This may allow different colours and/or colour temperatures to be achieved simply by brightening certain LEDs which have different colours of diffusion above them.

The second or further approaches may provide the ability to create a device with the possibility to select low blue light without needing to have it permanently. Additionally or alternatively a way to achieve mixing of colours using PWM from single colour LEDs rather than using different colour LEDs may be achievable.

Considering the further approach in more detail, the following describes a staggered optical diffuser as mentioned above. This may be implemented together with any of the drive schemes as described herein for fine control of LED light level. Additionally or alternatively it may be implemented in an aromatherapy unit as described herein.

Fig. 9 shows one example of a light source having a staggered diffuser arrangement. Specifically, the light source comprises a PCB 91 having mounted thereon pluralities of LEDs 90a, 90b having positional correspondence to respective first diffuser elements B1 and second diffuser elements B2 as indicated by the B1 , B2 indications in Figs. 9 and 10. The LED drive scheme used with such a diffuser may involve a combination of pulse width modulation and amplitude modulation (however, merely for clarity, Fig. 11 shows only PWM output as indicated by PWM drivers PWM1, PWM2 receiving drive input from a shared controller, e.g., processor such as a microprocessor that may optionally provide all control functions to ultimately provide the PWM 1/2 outputs based on input to the controller either triggering a preset control of the LED banks and/or setting a colour change profile to ). The drive scheme may be as described herein for fine control of LED light level. As mentioned above, such a scheme may be advantageous for controlling LED light at the very low output levels required to mimic the beginning of dawn. Preferably, the unit may then provide a continuous brightness sweep with substantially no perceptible brightness discontinuity.

Example functions of the staggered diffuser are to: produce softer and more desirable colour and/or colour temperature of LED light; and/or reduce, by way of filtering (which may be controllable at the option of the user), the amount of blue light emitted. For example, a light source such as for use for reading before bedtime may desirably emit a non-alerting overall light colour. Such a light source may comprise all white LEDs however further comprising both transmissive diffuser elements and diffuser elements that block blueish light, e.g., substantially block wavelengths below 530nm and/or having a pass band not extending below 530nm. The light may be pre- configured or set by a user to provide a desired, preferably constant, colour of light comprising the desired amount of blueish light.

The general construction of an example diffuser arrangement is shown in Fig. 9. The printed circuit board (PCB) with LEDs on it may be at the base and the diffuser/filter directly above the PCB. Over the top of everything, there may also be a (generally white) semi-transparent, preferably plastic, surface that is seen by the customer as a uniform light source (see, e.g., the optional globe surface 93 of Fig. 9).

In an example, there are two banks of white LEDs, each of which the controller is able to adjust independently in terms of brightness. Two such banks are shown in Fig. 11. LEDs in both banks may be all exactly the same colour and/or type. However, each bank has an optical diffuser/filter above it of different colour. This may allow limited rendering of net-perceivable colour on the outside globe.

On the PCB, the LEDs from two banks may be interlaced, rather than grouped, preferably across the entire available real estate. Fig. 10 shows a simplified pattern with LEDs from bank 1 (B1) and bank 2 (B2) arranged in a two-dimensional matrix, looking perpendicular to the surface.

An example embodiment may be able to control the amount of blue light, intrinsically generated by the white LEDs, to which the user is exposed to at certain times of the day. Regarding the two banks of LEDs, all said LEDs may be of the same type and emitting white light. Each bank may be controlled using preferably a PWM driving scheme (for example as described herein) so as to allow the power output of each bank to be set independently of each other, as shown in Fig. 11. In a physical printed circuit board implementation, the two banks of LEDs may be placed in a 2D matrix, in which bank 1 (B1) LEDs and bank 2 (B2) LEDs are alternately placed in rows and columns in order to cover the entire optical surface area. The optical diffuser may then be placed directly above the LED matrix, where the said diffuser may have a colour filter pattern as shown in Fig. 10, and which would strictly line up with the correct LED positions on the PCB; each B1 position on the diffuser is directly above the bank 1 LED, and each B2 position on the diffuser is above the bank 2 LED.

The diffuser B1 positions may be preferentially translucent and allow the full colour spectrum of bank 1 LEDs through, whilst diffuser positions B2 may be optically filtered so as to minimise the transmission of blue light in the range between, e.g., 450 nm to 530 nm. By independently changing the output power of each LED bank from 0% to 100%, the perceivable light colour may be modified to effectively increase or reduce the amount of blue light emitted.

For dawn simulation where more blue light is desirable, B1 LED bank may be more dominant. For sunset simulation where reduction in blue light is advantageous, the B2 LED bank may be more dominant in terms of power output.

In an embodiment, by decreasing the brightness of B1 group of LEDs, to which the filter has not been applied, a reduction in emitted blue light may be observed. This may produce light which is suitable for a sunset application. For reduction in blue light, blue light (e.g. below 530 nm) may be either partially or substantially filtered out.

If the adjustment is reversed and B1 group is made brighter than B2, the amount of blue light may increase. This light may be more suitable for a sunrise profile.

Some colour rendering within the constraints of two available source colours may thus be possible and could be used to enhance user perception of light quality.

The invention further provides processor control code to implement the above- described system and control procedures, for example on an embedded processor and/or microprocessor. Such code may be for controlling the drive level and duty factor in accordance with an embodiment. The code may be provided on a carrier such as a disk, CD- or DVD-ROM, programmed memory such as read-only memory (Firmware), or on a data carrier such as an optical or electrical signal carrier. Code (and/or data) to implement embodiments of the invention may comprise source, object or executable code in a conventional programming language (interpreted or compiled) such as C, or assembly code, code for setting up or controlling an ASIC (Application Specific Integrated Circuit) or FPGA (Field Programmable Gate Array), or code for a hardware description language such as Verilog (Trade Mark) or VHDL (Very high speed integrated circuit Hardware Description Language). As the skilled person will appreciate such code and/or data may be distributed between a plurality of coupled components in communication with one another.

No doubt many other effective alternatives will occur to the skilled person. It will be understood that the invention is not limited to the described embodiments and encompasses modifications apparent to those skilled in the art lying within the spirit and scope of the claims appended hereto.