There is a growing provision of motorised aircraft seating that reclines to form a bed while giving selectable seating positions during its travel. Existing control units contain a transformer to which the mains AC voltage is applied and which steps down the AC voltage to a level above the required output voltage. This voltage is then rectified and fed into a voltage regulator circuit. The voltage regulator gives a constant output voltage for varying mains voltage.

To obtain a constant voltage out of the regulator a higher voltage must be applied to the regulator to account for peaks and troughs of the applied voltage. The difference between input and output voltages will be dissipated as heat. The conventional mains transformer and regulator have a low efficiency. This wastes power generated by the aircraft, resulting in substantial heat generation by the control unit and increased fuel consumption on the aircraft.

The heat generation also gives rise to further increased fuel consumption due to the cabin air-conditioning units needing to working harder to remove the unwanted heat. The transformer and internal components of this type of control unit are by nature large and heavy; a typical unit would measure 350x250xlOOmm and weigh approximately 2 Kgms. This again gives increased fuel consumption due to the weight but also limits the seating space available owing to its size.

The existing control units produce high frequency radio emissions, which are shielded by a metal outer casing to prevent interference with nearby electrical equipment. In spite of provision of the casing these emissions have a

tendency to leak beyond the casing and produce such unwanted interference. Actuators are used to move the seats and are comprised of electric motors with respective gear trains or of pneumatic motors. The actuators comprised of electric motors and gear trains are inefficient, again resulting in power loss and increased weight. At present a typical passenger aircraft could contain 48 such seats and the requirement is continually rising, although limited by heat generation and weight. Conventional seat control systems monitor the overall current drawn by the electrically motorised actuators to detect motor overload due to a fault or the motor jamming. The level the current reaches before the motor is stopped by the control system is governed by the maximum normal operational current and the current level of the switching-on surge. This means that the current overload force has to exceed the maximum operational force before the actuator is switched off. As a result a relatively high force can be applied to an obstruction, for example part of a user's body, before the actuator is switched off. Such existing control units employ electro magnetic relays for drive switching purposes. These cause problems of EMC emissions owing to relay contact arcing and switching transients, such transients being very high current surges at the moment of switching-on. Such EMC emissions interfere with radio and other electrical equipment. Electromagnetic relays do not allow high motor switching speeds. It is usual for a group of actuators to serve a particular aircraft seat which would normally be in at least three parts all pivotally movable relative to each other. This group of actuators is supplied through a resistor which, by means of monitoring circuitry, is used to measure the current flow level through the group as a whole.

Such an arrangement cannot distinguish between normal current levels through all actuators, on the one hand, and an excessive current level through one actuator and very low current levels through the other actuators, on the other hand.

Furthermore, existing control units for motorised seating in aircraft incorporate microprocessors with external clock oscillators, ROM's (read only memories), RAM's (random access memories), peripheral input/output devices and data lines. These components occupy significant amounts of PCB (printed circuit board) space and generate significant amounts of EMC emissions. Moreover conventional control units use voltage or tone generation for communication between the microprocessors and the actuators and the like.

Such means of communication can be readily disturbed by EMC emissions and suffer from rapid degradation of signals over long distances.

A typical fully reclining seat consists of a framework containing three articulated seat panels that can be moved using an actuator including an electric motor, which through a gear train either revolves a pinion gear to extend a gear rack or revolves a nut to extend a lead screw. The articulated panels may be moved by just one actuator or a number of actuators; two or three actuators are normally used, one per seat panel. The resistance to back drive of the actuator is normally used to prevent the seat from moving from the position selected by the passenger. The actuator gear train is therefore a compromise between the optimum gear train for speed and power consumption of the actuator and the gear train required to prevent back drive.

This results in low efficiency of the actuator and heat generation by both the actuator and the power supply.

Insofar as the seat parts move relative to each other from their normal condition, which is that of a fully upright seat, known as TTL (taxi-take off and landing), to their fully reclined condition, which is that of a bed, they all move downwardly, and, on returning to the TTL position, they all move upwardly. This can produce a sensation for the occupant that he is slipping out of the seat.

Actuators used in aircraft seating are required to have a manual release mechanism so that the seat can be returned to the TTL position if the power supply is switched off or fails, or if the electric motor fails and is replaced. This causes a problem with position sensing of the actuator rack or lead screw.

If the power is switched off or fails, when the power is restored the control arrangement for the actuator needs to know the exact position of the actuator rack or lead screw.

Similarly, if the manual release mechanism has been used, the control arrangement needs to know the exact, new position of the rack or lead screw. This is normally achieved by using either contact switches which simply indicate if the actuator is at one of its extremes of travel or a potentiometer that is coupled to the rack or lead screw movement by gear wheels and gives a voltage dependent on the position of the rack or lead screw. These methods of position sensing are prone to mechanical wear and failure.

They are also relatively heavy and substantially add to the size of the actuator.

Existing control units have push-button switches for initiating and stopping seat movement. The seat moves as long as the operator is pressing the button. Upon negative operation of the switch, i. e. removal of pressure from the button, seat movement stops. This can be inconvenient to the operator in requiring him to keep his finger on the button throughout the movement. Moreover, if the seat is unoccupied it will move if the button is pressed, which could result in unexpected and thus dangerous movement of the seat. In conventional systems the pilot can override control by seat occupants and disable seat movement. When the existing seat is in the form of a bed, anyone can stand with his whole weight on any part of the bed and this requires all parts to be constructed strongly enough to bear the weight of the heaviest person.

Mechanically and electrically controlled aircraft seating requires a latching mechanism to clamp the seat in the TTL position and a mechanism to confirm that the latch is in the correct position for engagement. This is achieved by the use of an electrical solenoid to perform the locking and an electrical switch to confirm the positioning. A mechanical indicator is also included to confirm the position of the latch in the case of a loss of power.

The solenoid consists of a large coil of wire that forms an electromagnet and pulls in a steel pin that is attached to the latch mechanism. The latch mechanically retains the seat in the TTL position and the solenoid releases the latch when

the seat is to be reclined. The solenoid and switch assembly can weigh over 1 Kg and is physically large. To retract the pin using a solenoid requires an intense magnetic field, which requires a large heavy coil of wire and a high current (typically 4 to 8 Amps) to operate.

The initial seat profile is considered of great importance by the airlines as this is the first impression a passenger has of the seat and it may be some time before the passenger is able to adjust the initial seat profile. A number of ways are used to provide lumbar support on an aircraft seat, such as a mechanical fabrication, an air-filled bag or a foam- plastics-filled bag. Each of these has disadvantages.

A known air bag system has the air bag fully deflated for the initial seat profile giving a void for the initial lumbar position and, during inflation of the air bag, a ridge of high pressure in the lumbar region is usually encountered.

It is known to employ a foam-filled cushion which is at its maximum profile for the initial seat profile, which causes passenger discomfort. Air is then released via a valve from the cushion by the passenger while the passenger pushes against it to achieve a comfortable position. To re-inflate the cushion the passenger must move away from the cushion and open the valve to allow air to be drawn in as the foam expands to its original shape.

Conventionally, a leg rest of an aircraft seat has a cushion filled with foam plastics.

The ever-increasing number of functions, e. g. seat control, lighting control, and entertainment system control, available at motorised aircraft seats requires switch pads with a corresponding number of switches. This means a confusing array of switches and symbols presented to the passenger. Also there is no facility to pass information back to the passenger, such as an error in his use of the seat or an attempt by him to operate the seat while in the TTL condition.

A conventional switch mode power supply to computers, for example, uses a step down transformer so a low voltage is switched and a separate inductor is used to provide the output voltage. Also known is an offline switch mode power supply in which the AC mains supply is directly switched to provide output regulation. Such switch mode supplies have internal resistances of at least 10 ohms. An offline power supply rectifies and smoothes the AC mains to give a high voltage DC power source. This DC is then applied to a transformer, series connected to an electronic switch. If the switch is open-circuit no current flows. By operating the switch at a desired frequency, power will flow in the transformer secondary and this can be rectified and smoothed to produce the required DC output voltage. The power delivered to the secondary is controlled by a feedback voltage from the output of the power supply which alters the pulse width of the switching signal and hence the energy stored in the transformer. Using this method the output voltage is directly regulated by the power drawn from the power supply, i. e. if the output takes high current the transformer will supply high power, and if the output draws

no current the transformer will deliver only enough power to drive the control circuitry.

Mu-metal screening is known for use with audio-frequency equipment, mu-metal being a metal that absorbs magnetic radiation.

According to a first aspect of the present invention, there is provided motorised furniture apparatus comprising first and second parts of furniture of which the first part is movable relative to the second part, a drive device connected to said first part and serving to move said first part relative to said second part, and a control arrangement serving to control said drive device, said control arrangement including a switch mode power supply arrangement serving to supply power to said drive device.

Owing to this aspect of the invention, it is possible to improve power efficiency and thereby reduce heat generation and to reduce the weight and size of the apparatus.

The furniture may be, for example, a medical bed or medical seating, or seating in a vehicle, such as a road or rail vehicle, a ship, or an aircraft.

According to a second aspect of the present invention, there is provided a vehicle including an electrically powered device, and a switch mode power supply arrangement serving to supply power to said device.

Owing to this aspect of the invention, it is possible to improve power efficiency and thereby reduce heat generation.

The vehicle may be a road or rail vehicle, a ship, or an aircraft, and the electrically powered device may be motorised furniture or a computer in the vehicle, particularly an aircraft.

According to a third aspect of the present invention, there is provided energy storing apparatus comprising an energy storing device comprised of input and output windings and at least one core and designed for operation with an electrical input of a frequency in the range from 50 Khz (kilohertz) to 200 KHz, and a casing of mu-metal and receiving said energy storing device.

Owing to this aspect of the invention, it is possible to provide energy storing apparatus which emits an extremely low level of electromagnetic radiation.

The mu-metal serves to remove low frequency harmonics of the frequency in question, which is preferably about lOOKhz to give optimum power transfer with optimum RF (radio frequency) emissions, whilst the casing, especially if earthed, serves to remove higher frequency components.

This energy storing apparatus is particularly suitable for use in the switch mode power supply arrangement of the apparatus according to the first or second aspect of the invention, which is preferably an offline switch mode power

supply arrangement, with the switching frequency being between 50Khz and 200Khz, preferably about lOOKhz, in order to give optimum power transfer with optimum RF emissions.

According to a fourth aspect of the present invention, there is provided a switch mode power supply arrangement having an internal switching resistance of less than 2 ohms.

Owing to this aspect of the invention it is possible to increase current output and reduce electrical losses and thus heat generation.

The internal switching resistance is preferably less than 1 ohm, especially less than 0.25 ohm, even down to 0.05 ohm or less.

According to a fifth aspect of the present invention, there is provided a switch mode power supply arrangement having over-current shut-down circuitry to prevent operation of said arrangement in the event of occurrence of excessive supply current.

Owing to this aspect of the invention it is possible to avoid supply of current to produce damage to the arrangement or the equipment supplied thereby and/or to prevent unwanted operation of the equipment.

According to a sixth aspect of the present invention, there is provided a switch mode power supply arrangement having thermal shut-down circuitry to prevent operation of said

arrangement in the event of occurrence of excessive switching temperature.

According to a seventh aspect of the present invention, there is provided motorised furniture apparatus comprising first and second parts of furniture of which the first part is movable relative to the second part, a drive device connected to said first part and serving to drive said first part to move said first part relative to said second part, and an electronic switching arrangement serving to control said drive device.

According to an eighth aspect of the present invention, there is provided a vehicle including an electrically powered device, and an electronic switching arrangement serving to control said electrically powered device.

The vehicle may be a road or rail vehicle, a ship, or an aircraft, and the electrically powered device may be motorised furniture or a computer in the vehicle, particularly an aircraft.

Owing to these two aspects of the invention, it is possible to reduce RF emissions and to reduce component wear and thus maintenance, as well as to reduce heat generation, weight and size, and also to enable increased drive device switching speeds.

The electronic switching arrangement is preferably a semiconductor ic (integrated circuit); for control of the

drive device in opposite senses of operation, it is a full bridge driver ic.

According to a ninth aspect of the present invention, there is provided an integrated circuit arrangement having an internal switching resistance of less than 2 ohms.

Owing to this aspect of the invention it is possible to increase current output and reduce electrical losses and thus heat generation.

The internal switching resistance is preferably less than 1 ohm, even down to 0.05 ohm or less.

This integrated circuit arrangement is particularly usable with the device of the first or second aspects of the invention.

According to a tenth aspect of the present invention, there is provided an electrical drive arrangement comprising a plurality of motors, a plurality of sensing resistors in series with the respective motors and a plurality of circuits connected to the respective resistors and serving to read the respective current flow levels through the respective resistors.

Owing to this aspect of the present invention it is possible continually to monitor the current consumptions of the respective motors, for example so that the electrical power supplied to any one of the motors is reduced in the event

that the current flow level through the motor exceeds a threshold level.

This drive arrangement is particularly usable in the first or second aspects of the invention.

According to an eleventh aspect of the present invention, there is provided a drive apparatus comprising an electrical drive device, and a determining, storing, comparing and influencing arrangement serving continually to determine the current consumption by the drive device, to store temporarily the determined values, to compare later determined values with the stored determined values and to influence the drive device accordingly.

According to a twelfth aspect of the present invention, there is provided a method of monitoring an electrical drive device, comprising determining continually the current consumption by the drive device, storing temporarily the determined values, comparing later determined values with the stored determined values and influencing the drive device accordingly.

Owing to these two aspects of the present invention it is possible continually to monitor the current consumption of the drive device and to take any necessary action in the event that a change of current consumption exceeds a desired maximum.

This drive apparatus is particularly usable in the first or second aspect of the invention.

According to a thirteenth aspect of the present invention, there is provided motorised furniture apparatus comprising first and second parts of furniture of which the first part is movable relative to the second part, a drive device connected to said first part and serving to move said first part relative to said second part, and a micro-controller arrangement serving to control the drive device.

The furniture may be, for example, a medical bed or medical seating, or seating in a vehicle, such as a road or rail vehicle, a ship, or an aircraft.

According to a fourteenth aspect of the present invention, there is provided a vehicle including an electrically powered device, and a micro-controller arrangement serving to control the electrically powered device.

The vehicle may be a road or rail vehicle, a ship, or an aircraft, and the electrically powered device may be motorised furniture or a computer in the vehicle, particularly an aircraft.

Owing to these two aspects of the invention, it is possible to improve power efficiency and thereby reduce heat generation and to reduce the weight and size of the apparatus.

With the micro-controller containing an internal microprocessor, an internal ROM (read only memory) or flash memory, an internal RAM (random access memory), at least one internal peripheral driver, an internal clock oscillator and internal data busses, EMC (electromagnetic compatibility) emissions are minimal.

Very advantageously, the micro-controller arrangement includes a plurality of micro-controllers, especially two micro-controllers, to reduce task loading compared with a single micro-controller, and thereby reduces the operating frequency of the micro-controller arrangement, so as to reduce EMC emissions, as well as current consumption and this heat generation, without degrading performance.

According to a fifteenth aspect of the present invention, there is provided motorised furniture apparatus comprising first and second parts of furniture of which the first part is movable relative to the second part, a drive device connected to said first part and serving to move said first part relative to said second part, said drive device comprising a motor mechanically connected to said first part and first logic circuitry serving to control said motor, and second logic circuitry remote from said first logic circuitry, the first and second logic circuitries being arranged to communicate via digital data.

According to a sixteenth aspect of the present invention, there is provided:-

motorised furniture apparatus comprising first and second parts of furniture of which the first part is movable relative to the second part, a drive device connected to said first part and serving to move said first part relative to said second part, and first logic circuitry serving to control said drive device, and second logic circuitry remote from said first logic circuitry, the first and second logic circuitries being arranged to communicate via digital data.

Advantageously, the first and second logic circuitries are arranged to communicate with each other via a data exchange protocol.

According to a seventeenth aspect of the present invention, there is provided a vehicle including an electrically powered device, first logic circuitry serving to control said drive device, and second logic circuitry remote from said first logic circuitry, the first and second logic circuitries being arranged to communicate with each other via a data exchange protocol.

Owing to these four aspects of the invention it is possible to reduce the weight and size of conductors used and to increase the flexibility of the system in the sense that further motorised furniture apparatus or electrically powered devices can be easily added to the system.

According to an eighteenth aspect of this invention there is provided a position-sensing apparatus comprising a microcontroller arrangement, for receiving digital pulses

indicating detected movements, a non-volatile memory serving to store the detected movements, and electrical circuitry connected to said memory and serving to provide the stored detected movement in the form of a data protocol.

According to a nineteenth aspect of this invention, there is provided a method comprising detecting movement of a member, emitting digital pulses indicating the detected movement, storing the detected movement in a non-volatile memory and providing the stored detected movement in the form of a data protocol.

Owing to these two aspects of the invention it is possible to remove all moving parts from the position sensing apparatus.

According to a twentieth aspect of the present invention, there is provided motorised furniture apparatus comprising first and second parts of furniture of which the first part is movable relative to the second part, a first drive device connected to said first part and serving to move said first part relative to said second part, and a second drive device connected to said second part and serving to move said second part relative to said first part, the arrangement being such that said first drive device is able to move said first part upwardly while said second drive device moves said second part downwardly and that said first drive device is able to move said first part downwardly while said second drive device moves said second part upwardly.

According to a twenty-first aspect of the present invention, there is provided a method comprising moving upwardly a first part of motorised furniture apparatus while moving downwardly a second part thereof and subsequently moving downwardly said first part while moving upwardly said second part.

Owing to these two aspects of the invention, the change of seat profile can be made more acceptable to the user of the furniture.

According to a twenty-second aspect of the present invention, there is provided motorised furniture apparatus comprising first and second parts of furniture of which the first part is movable relative to the second part, a drive device connected to said first part and serving to move said first part relative to said second part, and a control arrangement serving to control said drive device and including a manually operable switch and so arranged that a first positive operation of said switch starts said drive device and a second positive operation of said switch stops said drive device.

According to a twenty-third aspect of the present invention, there is provided a method of controlling motorised furniture apparatus, comprising performing a first positive manual operation of a switch to start a drive device to move a first part of furniture relative to a second part thereof and performing a second positive manual operation of said switch to stop said drive device.

Owing to these two aspects of the invention, it is possible to provide for operation of the drive device in a manner which is more convenient to the user.

Advantageously, the first positive operation automatically runs the first part through a maximum range of movement relative to the second part, or runs it to a pre-set point in that range, unless, of course the second positive operation is performed.

According to a twenty-fourth aspect of the present invention, there is provided motorised furniture apparatus comprising first and second parts of furniture of which the first part is movable relative to the second part, a drive device connected to said first part and serving to move said first part relative to said second part, and a control arrangement serving to prevent operation of said drive device while said furniture is not occupied by a user.

Owing to this aspect of the invention, it is possible to prevent unwanted operation of the drive device.

If desired, the apparatus may include an override facility whereby the function of the control arrangement of preventing operation of the drive device can be overridden.

According to a twenty-fifth aspect of the present invention, there is provided motorised furniture apparatus comprising first and second parts of furniture of which the first part

is movable relative to the second part, a drive device connected to said first part and serving to move said first part relative to said second part, and a control arrangement serving to operate said drive device and itself controllable by radiation of data from a remote source of said data.

Owing to this aspect of the invention, it is possible to render operation of the drive device more convenient for the user.

Advantageously, the data is radiated in the form of RF radiation from a smart card or similar.

According to a twenty-sixth aspect of the present invention, there is provided in combination : - motorised furniture apparatus comprising first and second parts of furniture of which the first part is movable relative to the second part, a drive device connected to said first part and serving to move said first part relative to said second part, and a control device operable by an occupant of the apparatus to control the operation of said drive device, and a remote device operable by a person other than the occupant and serving to receive data from said apparatus.

Owing to this aspect of the invention, it is possible to receive a wide variety of useful data relating to the apparatus.

According to a twenty-seventh aspect of the present invention, there is provided motorised furniture apparatus comprising first and second parts of furniture of which the first part is movable relative to the second part, a drive device connected to said first part and serving to move said first part relative to said second part, and a detecting device serving to detect the application of excessive force to said first part and a control arrangement actuatable by said detecting device to cause said drive device to operate to move said first part relative to said second part in the sense of said force.

Owing to this aspect of the invention, it is possible to avoid the excessive force being applied to the first part for any significant period of time.

According to a twenty-eighth aspect of the present invention, there is provided a drive arrangement, comprising a motor, a speed-reducing transmission connected to the output of said motor, and a brake applicable to said transmission at a higher-speed region thereof.

Owing to this aspect of the invention, it is possible to prevent back-drive while the brake is applied and allow back-drive of the motor while the brake is removed.

According to a twenty-ninth aspect of the present invention, there is provided motorized furniture apparatus comprising first and second parts of furniture of which the first part is movable relative to the second part, a drive device

connected to said first part and serving to move said first part relative to said second part, and a graphics/user interface comprising a screen having a plurality of areas sensitive to the presence of a user's finger and whereat can be displayed respective graphic symbols representing respective functions, at least one of said functions comprising control of said drive device by an occupant of said furniture.

Owing to this aspect of the present invention, it is possible to replace a number of individual switches by a single screen and also relatively easily to add more functions.

According to a thirtieth aspect of the present invention, there is provided apparatus for supporting a human body part comprising a substantially air-tight, inflatable cushion, a readily resilient solid material contained in said cushion and occupying at least a major proportion of the plan area of the cushion and, in an unstressed condition of the solid material, occupying only part of the depth of the cushion when fully inflated, said apparatus further comprising a device whereby the cushion can be inflated and deflated by supplying gaseous medium thereto and evacuating gaseous medium therefrom.

Owing to this aspect of the present invention, the cushion can initially support the body part in an intermediate condition and then be inflated or deflated to reach the desired condition of support.

According to a thirty-first aspect of the present invention, there is provided apparatus for supporting a human body part comprising a substantially air-tight, inflatable cushion, a readily resilient solid material contained in said cushion and occupying at least a major proportion of the plan area of the cushion, said apparatus further comprising a pumping device serving to inflate and deflate said cushion by supplying gaseous medium thereto and withdrawing gaseous medium therefrom.

Owing to this aspect of the invention, the inlation or deflation of the cushion to a desired condition of support can be performed relatively easily.

According to a thirty-second aspect of the present invention, there is provided apparatus comprising a movable part, a releasable latching arrangement which serves to retain said movable part in a desired condition, said latching arrangement including a rack-and-pinion device, a latching member arranged to engage releasably said movable

part, and a motor arranged to rotate the pinion and thereby displace said rack longitudinally and thus operate said latching member.

Owing to this aspect of the invention, the latching mechanism can be relatively light in weight and consume relatively less power.

A preferred embodiment of the present invention uses an offline switch mode power supply to improve power efficiency and reduce heat generation, weight and physical size. The power supply has a theoretical efficiency of 98% owing to its method of operation, this giving very low energy losses resulting in less heat generation and less wasted energy from the aircraft mains power supply. The embodiment has a switching frequency of about lOOKhz which enables a physically small energy storing device, which we call a switching transformer", to be used, which results in low weight and footprint area. A control unit weighing 300gms and measuring 140x85x32mm can achieved. To utilize the efficiency of the control unit, a number of innovations can be incorporated as described hereinafter to provide a complete, high-efficiency system.

In the preferred embodiment, the switching frequency of the offline switch mode power supply is chosen to give optimum power transfer with minimal RF emissions. Mu-metal screening can be employed to prevent electric and magnetic field radiation from the switching transformer of the supply. The

internal switching resistance is very low, i. e. less than 0.25 ohm, to enable high current output with low electrical losses and low heat generation. The offline switch mode power supply has a soft start (low power start-up routine) to prevent switching-on surges from the aircraft power source. A thermal shut-down mechanism is included in the supply to prevent over-temperature operation and operation under fault conditions. Moreover, an over-current shut-down mechanism is provided to prevent operation under fault conditions or abnormal load demand.

The preferred embodiment uses a semiconductor full bridge driver integrated circuit to provide high efficiency control of the actuator motor in a very small surface area and a greatly reduced weight. The driver integrated circuit has exceptionally low internal resistance, which reduces both current loss and heat generation.

The semiconductor switching in the form of an integrated circuit is used to remove the problems of relay contact arcing and switching transients, as well as to reduce the problems of EMC emissions and to enable high motor switching speeds. Continuous current consumption of each motor can be constantly monitored by the use of circuitry internal to the integrated circuit and an external sensing resistor for each motor. A low-value high-stability sensing resistor (less than 500milli ohms) is used to minimise motor high-load power loss and heat generation. Consecutive current readings are taken to monitor and track the normal current usage of the motor for the loading at any instant from the motor

drive being activated. A preset cut-off differential for the current can track the motor loading current and remove the drive current if any sudden current rise exceeds the preset cut-off differential (which may be between lOmA and 2A).

In the preferred embodiment, the control unit includes a micro-controller to reduce surface area, weight and ancillary components. The micro-controller contains internal ROM (or, preferably, flash memory), RAM and peripheral drivers, greatly reducing the surface area required for the logic processing. It also contains internal analogue-to- digital converters, so reducing surface area. It further contains an internal clock oscillator, which substantially reduces EMC emissions. All data busses are internal to the micro-controller, so reducing EMC emission. The embodiment uses two micro-controllers to reduce task loading compared to a single micro-controller, and to reduce the operating frequency of the micro-controllers, thereby reducing EMC emissions, current consumption and heat generation while not degrading performance.

The embodiment uses data exchange protocols for communication between the micro-controllers and external devices. It may use the SPI (serial peripheral interface) protocol for communications between internal and external micro-controllers. Also it may use the CAN bus protocol for communications between internal and external micro- controllers and CAN responsive devices, and further-more use RS485 line drivers for data lines between devices. The embodiment may use external"pods"that can contain sensors,

drivers, semiconductor switches, power supplies, CAN devices and micro-controllers. The pods are able to control the functions of external devices such as switch pads, actuators, solenoids, lighting, computer power supplies, or any external device that can be fitted to a seat and communicate with the control unit. Position sensing of each actuator may be performed by various methods to overcome the aforementioned problem associated with position sensing. The preferred embodiment can employ any one of the following four methods, which may be used on a seat containing one, two or more actuators.

Method (i) An infra red light emitting diode or similar light source provided at a reference point on the actuator is used to illuminate a reflective material attached to a clevis mounting point of the rack or lead screw of the actuator.

The light reflected back to a photodiode or similar light detector also provided at that reference point is measured, the light intensity being proportional to the distance the light has travelled. This varying light intensity is converted electronically to a varying output voltage or digital information. Problems of dust build-up on the light- transmitting parts of the emitter and detector or in the air between the reflector and the detector can be compensated for by the use of a fixed value reference voltage. Using this method the position of the actuator rack or lead screw is always available following a loss of power or a manual movement of the rack or lead screw of the actuator, without the difficulties of mechanical wear and physical size.

Method (ii)

A series of parallel light and dark bands are applied round a ball nut of the actuator. It will be understood that, as the actuator ball nut rotates, a lead screw of the actuator is moved forwards or backwards depending on the sense of rotation of the nut. The bands are detected by an opto switch that gives an electrical output pulse for each line that passes the opto switch during the rotation of the ball nut. The pulses are electronically counted and stored in a non-volatile memory, i. e. the stored value will be retained if the power to the memory is removed. This stored value can be converted to a varying voltage level or digital information. An opto switch can also be used to monitor an end limit of movement of the actuator, so that if the power fails or the actuator rack or screw is moved manually the seat will be returned to the TTL position when the power is restored.

Either of the above methods (i) and (ii) can also be achieved using magnetic field emitters and detectors such as magneto resistive or Hall effect devices instead of the light source, refelctor and detector of method (i) or the bands and opto switch of method (ii).

Method (iii) The actuator is driven by a series of electrical pulses (pulse width modulation). If the pulses are of a fixed duration the distance travelled by the actuator rack or lead screw is proportional to the number of pulses. A problem with this position sensing is if the motor jams the pulses continue and give false position data. This is overcome by monitoring the current flow during each pulse and comparing it to the stall current of the electric motor of the

actuator; the pulses are stopped if the stall current is reached.

The number of pulses counted for each travel can be electrically converted to give a varying voltage output or digital data.

Again, a light or magnetic field detector can be used to monitor an end limit of actuator movement.

Method (iv) Position sensing is derived at the actuator from a potentiometer continually meshed into a gear train of the actuator.

In those instances where the positional representations are in a digital format, the digital pulses are converted by a micro-controller and stored in non-volatile memory to provide CAN bus or similar data format communications with the control unit. Up to 200 individual profile steps can be programmed per motor. The profile steps can control both forward and reverse actuator movement in the same profile movement, enabling precise profile control in the downward direction and upward direction. This means that parts of the seat could move upwards during the generally downward profile movement and similarly some parts of the seat can move downwards during the generally upward profile movement.

One-touch switch control can automatically run the seat through a full profile or to a preset profile point. A second press of the switch instantly stops the seat. The current through the actuator motor can be monitored to permit preventing the automatic seat movement if the seat is

empty. Individual nodes containing micro-controllers or line driver ic's can be connected together to form an intelligent network that can control a seat profile and ancillary devices without a central control unit via a two-or four- wire cable loom that links all relevant components. Stored information on a radio link smart card or similar can be used by the passenger or an airline stewardess to set the seat profile to the best match for a particular passenger's height or other requirements. A hand-held, external control unit can be used by the stewardess to adjust the seat position and give a direct readout of positional information, and/or to store and adjust the seat profile to meet the requirements of a range of disabilities, and/or by a maintenance engineer to give a diagnostic test and fault readout for the seat controller and actuators.

For passenger control of functions of such things as the seat, lighting and entertainment system, the preferred embodiment has a liquid crystal graphics display screen with a touch sensitive layer bonded onto the display screen.

Simple graphic symbols demonstrate the various functions, eliminating the language barriers of text-based instructions. The functions are divided into separate screen areas, are represented by 2 or 3 graphic symbols, and can be selected by touching the required symbol. A menu shows symbols for all of the available functions and touching a symbol will result in option symbols for sub-functions being displayed. When a function is selected either the symbol flashes to show it has been selected or an error symbol is displayed. This has the advantage that a large number of switches can be replaced by a single screen and more

functions can be added at any time without the need for mechanical alteration of the seat. Diagnostic and maintenance information with regards to the seat controller and the actuators is also displayed when a code is entered by a maintenance engineer.

In the preferred embodiment there is automatic footrest and leg rest retraction if the seat is fully reclined and an adult, full weight is applied to the footrest or leg rest, i. e. he stands on the end of the bed or climbs over an adjoining seat in the bed position. This retraction is achieved by monitoring the amount of movement at a pivot of the leg rest.

To clamp the seat in its TTL position, the preferred embodiment utilises a small dc electrical motor or stepper motor to operate a rack and pinion. Since an intense magnetic field is not required, the electric motor can have a low operating current (less than 0. 2Amps). A relatively small rack can be used to operate the latch. The motor can be accurately controlled and positioned, so removing the need for a position switch. The speed and progress of the rack can also be accurately controlled to give an operational profile to the latch if required.

The latching arrangement weighs less than 150gm and uses less than 20mA.

An optical detector or magnetic field detector, such as a Hall effect detector, can be used to monitor the latch position. The latching device is powered from a high value

capacitor (approximately 1 Farad) to store an electric charge and in the event of a power failure illuminates an indicator to show that the seat latch is engaged, removing the requirement for a relatively large mechanical indicator.

The illumination time is dependent on the size of the capacitor and can be set to between a few seconds and in excess of 2 hours.

If desired, this latching arrangement can be used for other purposes, for example latching a table or a television set in the aircraft in a desired position.

In the preferred embodiment, the lumbar support in the aircraft seat is provided by an airtight cushion equipped with an air inlet pipe to allow inflation and deflation. The cushion contains a block of readily resilient foam plastics.

The block occupies substantially the whole of the plan (i. e. face-on) area of the cushion, but, in an unstressed condition of the block, it occupies only part of the depth of the fully inflated cushion. An air pump is used to apply positive air pressure to inflate or a vacuum to deflate the cushion.

The advantage of this system is that the foam plastics block can be shaped to give a comfortable initial seating profile which can be adjusted either by vacuum from the air pump to compress the block to reduce the lumbar support or by positive pressure from the pump to increase the lumbar support to allow maximum comfort.

The use of the foam material in the cushion gives support to the whole lumbar region during decrease of the lumbar setting.

In the preferred embodiment, the leg rest is designed with a view to improving passenger comfort and providing some protection against deep vein thrombosis. The leg rest comprises, for the two legs, respective airtight sub- cushions containing respective readily resilient plastics foam blocks and equipped with respective air inlet pipes to allow inflation and deflation. An air pump is used to inflate and deflate each sub-cushion alternately to produce a relaxing massage effect. The use of foam material in the sub-cushions gives support to the legs when the passenger is using the seat without the massage feature switched on and during deflation. The foam material allows the legs to Using'into the sub-cushions with support around the legs.

In order that the invention may be clearly and completely disclosed, reference will now be made, by way of example, to the accompanying drawings, in which:- Figure 1 is a fragmentary, diagrammatic, side elevation of an aircraft fuselage showing a motorised aircraft seat reclinable to form a bed; Figure 2 is a diagram of electrical control and drive circuitry for the seat ; Figure 3 shows diagrammatically one of a plurality of actuators for the seat; Figure 4 shows diagrammatically a brake and solenoid mechanism of such actuator;

Figure 5 is a fragmentary, diagrammatic, vertical section through a transformer and circuit board of the circuitry of Figure 2; Figure 6 is a graph of current against time illustrating the current tracking for a motor of such actuator; Figure 7 is a simplified flow chart for software employed in the current tracking; Figure 8 is a diagram corresponding to Figure 2 but of a modified version of the circuitry; Figure 9 is a diagram similar to Figure 3 but showing a modified version of an actuator ; Figure 10 is a front perspective view of a sitting part and a backrest part of the seat, with a lumbar cushion fully inflated; Figure 11 is a diagrammatic section taken on the line XI-XI of Figure 10 ; Figure 12 is a front view of a leg rest cushion of the seat in one of two limit conditions of leg massage; Figure 13 is a view similar to Figure 12, but of the leg rest cushion in the other limit condition of leg massage ; Figure 14 is a front perspective view of the leg rest cushion in an inflated, non-massage condition ; Figure 15 is a view similar to Figure 14 but of the leg rest cushion in a deflated, non-massage condition; Figure 16 is a side elevation of a latching mechanism for releasably retaining the seat in its TTL condition;

Figure 17 is a perspective view of a display screen of various passenger-controlled functions at the seat ; and Figure 18 is a view similar to Figure 17 of the screen but showing various passenger-controlled sub- functions.

Referring to Figure 1, the aircraft has a fuselage 2 containing a horizontal partition 4 forming the floor of a passenger cabin containing a plurality of seats (of which one is shown and referenced 6). The seat profile is changeable between a TTL condition and a fully reclined condition in which it serves as a bed, through the intermediate position shown. The seat is shown in a simplified manner and comprises three upholstered parts, namely a leg rest part 8, a sitting part 10 and a back rest part 12. the upper end of the part 12 is guided so as to move substantially vertically, while its lower end zone is pivotally mounted on a link 14 pivotally mounted at its lower end on the partition 4. The lower end of the part 12 is connected by a horizontal pivot 16 to the rear end of the part 10, the forward end zone of which is connected by a lever 18 to the part 8. The lever 18 is connected to a lead screw 20 of an actuator 22 the casing 24 of which is securely pivotally mounted relative to the partition 4. This actuator 22 has the effect of turning the part 8 relative to the part 10 about a pivot 26 in the forward end zone of the part 10. At this pivot and fixed relative to the part 10 is a radially slotted disc 28 of an optical detection device.

At its rear end zone, the part 10 is pivotally connected to a lead screw 30 of an actuator 32 the casing 34 of which is

securely pivotally mounted relative to the partition 4.

Indicated at 36 is a control unit for the motors M of the actuators 22 and 32.

Instead of the actuator incorporating a lead screw, it may incorporate a rack-and-pinion device.

As indicated in Figure 3, each actuator 22 or 32 includes, in addition to the lead screw 20 or 30 a gear train 38 which rotates a nut 39 and so displaces the lead screw 20 or 30 longitudinally, and an electric drive motor 40 which drives the gear train 38. The actuator also includes a brake and solenoid release mechanism 42 manually renderable ineffective by means of a handle 44.

Referring to Figure 4, the mechanism 42 includes a friction pad 46 attached to a drive shaft 48 of the motor 40 by a boss 50 fixed to the shaft 48 and including a square section portion engaging in a square section aperture through the friction pad 46. This allows linear movement of the pad 46 along the motor drive shaft 48 but not rotational movement of the pad 46 relative to the shaft. Compression springs 52 push an annular, movable friction plate 54 against the friction pad 46, which slides along the shaft 48 until it is gripped between the plate 54 and a fixed friction plate 56 through which rotatably extends the boss 50. A solenoid 58 is energisable to attract the plate 54 against the action of the springs 52, so as to free the pad 46 and thus the shaft 48 for rotation. Otherwise, the friction pad 46 prevents the motor from rotating. If a manual brake release lever 60 is moved in the direction of the arrow A, the plate 54 is

thereby pushed against the action of the springs 52, so releasing the friction pad 46 and'allowing the motor 40 to be rotated by back drive or power applied to the motor 40.

Advantages of the actuator described with reference to Figures 3 and 4 are that high load torques can be achieved with less weight and lower wasted energy than with conventional actuators, faster speed of operation can be achieved using less power than with conventional actuators, whilst false operation of neither the motor nor the brake will cause the actuator to move.

The actuator uses the solenoid released friction brake 46,50-56, applied to the electric motor drive shaft 48, which is the highest speed point in the transmission and therefore has the maximum mechanical advantage to hold the seat in position. To change the seat position the solenoid 58 is energized, which releases the brake, and the actuator is then free to move the relevant seat part (s) to the position selected by the passenger. The brake mechanism also has the manually releasable lever 60 to enable the lead screw 20/30 to be moved in the event of power failure. This gives the advantage of allowing the optimum gear ratios to be used in the actuator gear train 38 to give low-current, high-torque operation, giving a considerable power saving and a high torque/weight ratio. This system presents both a weight saving and a power i. e. fuel saving.

When the seat 6 is fully reclined into a bed, the leg rest part 8 becomes the end of the bed and can be abused by passengers using it as a step to the overhead storage compartments or climbing over from an adjacent seat. To deter this abuse, an automatic retraction arrangement 62 is provided including a slotted disc 28 and an optical switch fitted at the pivot 26. When excessive weight is applied to the part 8, the small relative movement between the parts 8 and 10 causes the optical switch to change state and signal the control unit 36 to retract part 8. The part 8 will start to slowly retract within 50mS of weight being applied, so that the passenger will notice the movement before full weight is applied and therefore probably desist from the abuse. The downward force required to initiate retraction of the part 8 will depend on the size of the slots in the disc 28 and the mechanical advantage of the part 8. This arrangement works for virtually all positions of the part 8.

Alternatively, in a much simpler form, a micro-switch could be used to sense the movement when the seat is in the bed position only.

Referring to Figure 2, an offline switch mode power supply 64 is provided from the mains supply of the aircraft itself of for example, 115V at 400Hz. This input is rectified in a circuit 66 and smoothed in a circuit 68 and fed to an electronic switch 70, the output from which is fed to a high frequency switching transformer 72. The switching transformer output is rectified and smoothed in circuits 74 from which a feedback voltage is applied to pulse width

control circuitry 76, which controls the pulse width of the output of the switch 70. Included in the switch 70 is over- current shut-down circuitry 70a and thermal shut-down circuitry 70b to shut down the supply 64 in the event of, respectively, excessive current through and excessive temperature in the switch 70. The transformer 72 is mounted on a PCB 71 through which extend terminals 73 of the input and output windings 75 and 77 of the transformer 72. These windings and the core 79 of the transformer 72 are potted in resin 81 in a cup-form casing 83 of mu-metal.

Very high efficiencies can be obtained with this power supply 64 and, by choosing components with very low internal resistance, the circuit losses can be minimal, giving low power wastage and hence very low heat dissipation.

The supply 64 serves a plurality of micro-controllers (in this case two micro-controllers 80 and 82), as well as semiconductor full bridge driver integrated circuits 84 and 86 which correspond in number to the actuators (22 and 32).

Each circuit 84 or 86 comprises four transistors 88 which apply drive to the respective motors M. Each of the circuits 84 and 86 is earthed via a low-value, high-stability, sensing resistor 90, the voltage across each resistor 90 being transferred through data busses 92 to a multiplexer 94, to which is also transferred the data from the movement- sensing arrangement 62 and from position sensors 96 of the respective actuators 22 and 32 via data busses 98. Via a data bus 100 the multiplexer 94 transfers this data to the

micro-controllers 80 and 82 which each include an oscillator 102 connected to a microprocessor 104 itself connected via data busses 106 with RAM 108, non-volatile memory 110 (which is either ROM or flash memory) and one or more peripheral drivers 112. Via data busses 114,116 and 118, the micro controllers 80 and 82 are connected to a switch panel 120 whereby the passenger controls his seat 6, an auxiliary socket 122 for connection of a hand-held external, control unit 126, and a transceiver 124 for communicating with a radio link smart card 128. The control unit 36 prevents operation of the actuators 22 and 32 while the seat 6 is unoccupied. However, that function of the control unit 36 can be overidden by a staff member from, for example, the unit 26.'A series of switches 130 are connected by data busses 132 to the micro controllers 80 and 82, and to terminals 134 at the control unit 36 for switching external devices associated with the seat in question, such as lighting and table release.

In the modified version shown in Figure 9, each position sensor 96 comprises an infra red light emitting diode 96a fixed to the casing 24 or 34 adjacent the screw 20 or 30 (driven longitudinally by a ball nut 97 of the actuator) and used to illuminate a light reflector 96b in the form of reflective material attached to a clevis mounting 97. The light reflected back to a detector 96c in the form of a photodiode is measured, the light intensity being proportional to the distance the light has travelled. This varying light intensity is converted electronically to

digital information. Problems of dust build-up on lenses of the emitter 96a and detector 96c or in the air between the reflector 96b and the emitter 96a or detector 96c are compensated for by the use of a fixed value reference voltage. Using this method the degree of extension of the actuator lead screw 20 or 30 is always available following a loss of power or a manual movement of the lead screw 20 or 30, because a non-volatile memory arrangement 110 is employed to store the positional data in those circumstances.

Visible in Figure 9 are lateral busses 97a which receive respective pivot pins whereby the actuator 22 or 32 is pivotally mounted relative to the partition 4.

Software (which will be understood from Figure 7) in the micro controllers 104 is used to detect and measure the normal operational current, which is dependent upon the occupant's weight. The software also sets a current overload limit above that normal current. The limit can be set from just a few mA above the normal current up to any level below the motor stall current.

This function is illustrated in Figure 6, in which a is a current limit level as set for a conventional control unit for an aircraft seat, b is the motor switch-on transient current, c is the normal operational current, and d is a current tracking curve.

The normal operating current c is monitored and the current tracking curve d is the switch-off limit. A sudden rise in current to position X1 owing to an obstruction stops the actuator 22/32 before a serious overload occurs. Using a conventional system the current would have to rise to position X2, which would exert the full force of the actuator on the obstruction, which would almost certainly cause damage to the obstruction, which could be injury to the passenger. The current tracking also prevents damage occurring if a footrest (not shown) of the seat is fully deployed and collides with an obstacle or the aircraft floor.

The version shown in Figure 8 differs from that shown in Figure 2 in that non-intelligent devices, such as the actuators 22 and 32, the arrangement 62, the switch panel 120, the transceiver 124 and the switches 130, are intelligent and for that purpose each is provided with its own micro-controller 140. These micro-controllers can communicate with each other via 2-wire data buses 142. As indicated in Figure 8 by dot-dash lines, any number of actuators, with their own micro-controllers 140, can be provided. It will be seen from Figure 8 that those items requiring power supply for their operation are connected to power buses 144 extending from the output from the off line switch mode power supply 64. In a further alternative version of the circuitry, but not shown, the power buses 144 can also serve as the data buses, so that the data buses 142 can be omitted. These two modified versions have the

advantage that the amount of cabling required can be significantly reduced, so reducing the installation work needed and the weight and volume of the cabling. A further advantage is that additional items, such as additional actuators, can easily be added to or removed from the system as and when desired.

Referring to Figures 10 and 11, included in the backrest part 12 is a substantially airtight cushion 150 equipped with an air inlet pipe 151 to allow inflation and deflation.

The cushion contains a block 152 of readily resilient foam plastics. The block 152 occupies substantially the whole plan (i. e. face-on) area of the cushion 150 but, in an unstressed condition of the block 152 as shown, the block 152 occupies only part of the depth of the fully inflated cushion 150 as shown. An air pump 153 is used to apply positive air pressure to inflate or a vacuum to deflate the cushion 150.

The unstressed foam block 152 is shaped to give a comfortable initial seating profile which can be adjusted either by vacuum from the air pump 153 to compress the block 152 to reduce the lumbar support or by positive pressure from the pump 153 to increase the lumbar support to allow maximum comfort.

Referring to Figures 12 to 15, the leg rest 8 preferably includes a cushion 154 designed to improve passenger comfort and provide some protection against deep vein thrombosis.

The cushion 154 consists of two substantially airtight, inflatable cushions 155 and 156 each of which contains a block of readily resilient foam plastics of substantially the same plan area as the sub-cushion and of a depth less than that of the fully inflated sub-cushion.

The sub-cushions 155 and 156 are equipped with respective air inlet pipes 157 and 158 to allow inflation and deflation by an air pump 159. The pump 159 can be used to inflate and deflate the sub-cushions 155 and 156 alternately, one being inflated while the other is deflated, and vice-versa, as will be understood from Figures 12 and 13, to produce a relaxing massage effect. The use of foam plastics in the sub-cushions 155 and 156 gives support to the passenger's legs when using the seat without the massage feature activated and during deflation. The foam plastics allows the legs to into the sub-cushions with support around the legs.

Referring to Figure 16, the latching mechanism 160 engages with a transverse bar 162 of a movable part of the seat 6 to retain the seat in its TTL condition. The mechanism 160 includes a small dc electrical motor or stepper motor 164 to operate a rack-and-pinion device 166 of which the rack is pivotally connected to a latch member 168 for driving the member 168 to engage and disengage the same. The member 168 is pivotally mounted on a fixed part 170 of the seat. The electric motor 164 has a low operating current of less than 0.2Amps.

The rack 166 can be accurately controlled and positioned, removing the need for a position switch. The speed and progress of the rack 166 can also be accurately controlled to give an operational profile to the latch member 168 if required.

The whole mechanism 160 weighs less than 150gm and uses less than 20mA.

If desired, an optical detector or Hall effect detector can be used to monitor the position of the member 168. The mechanism 160 is powered from a high value capacitor (approximately 1 Farad) to store an electric charge and in the event of a loss of power can illuminate an indicator to show that the member 168 is engaged. The illumination time is dependent on the size of the capacitor and can be set to between a few seconds and in excess of 2 hours.

Referring to Figures 17 and 18, the switch panel can advantageously be replaced by a liquid crystal graphics display screen 180 with a touch-sensitive layer bonded onto the screen. Simple graphic symbols 182 (passenger control of the seat 6), 184 (passenger control of the lumbar support) and 186 (passenger control of his lighting) demonstrate the functions, so eliminating the language barriers of text- based instructions. The symbols are displayed in separate screen areas and their functions can be selected by touching the required symbol. A menu seen in Figure 17 shows the

symbols 182 to 186 for the functions, whilst touching one of the symbols will result in the sub-functions being displayed by symbols, such as seen in Figure 18, the symbol 188 being the sub-function of bringing the seat to its TTL condition, the symbol 190 being the sub-function of bringing the seat 6 to its'lazy Z"condition, and the symbol 192 being the sub- function of bringing the seat to its bed condition. When a function is selected either the symbol flashes to show that its function has been selected or an error symbol is displayed. More functions can be added at any time without the need for mechanical alteration of the seat 6. Diagnostic and maintenance information with regards to the seat control unit 36 and the actuators 22 and 32 is also displayed when a code is entered by a maintenance engineer.