Actuator system

The invention relates to an actuator system for an adjustable piece of furniture, comprising a housing, at least one actuator, a power supply, a control device and at least one control for adjusting the actuator system.

Linear actuators are widely used within the area of adjustable furniture such as hospital, care or comfort beds and adjustable chairs and tables. Linear actuators are also used for special furniture such as tables for flat screens and monitors, where the screen, when it is not being used, may be hidden in the piece of furniture and thus be protected.

In an actuator system, the actuator (s) are normally connected to a control device via one or more cables and the control device is further connected to a power supply and a control. This result in a number of cables, which can be a challenge during running of these and in connection with cleaning of the piece of furniture, but the cables may also obstruct the mechanical movement of the application. This may result in that the cables are damaged by being cut completely or partially in the application. Further, the cables are also a limitation for the user in connection therewith that the control for adjusting the actuator system may only be operated in the close proximity to the application.

In connection with the control, WO2006/039929 to Linak A/S discloses a wireless control for adjusting an actuator system. The actuator system, mentioned therein, is of the type comprising two actuators arranged in a

mutual housing and constitutes a complete system for an adjustable bed or armchair. In the normal version, the control constitutes a cabled control, where the embodiment in connection with WO2006/039929 is developed further based on this cabled control by, in a more sophisticated way, equipping it with a receiver for a further wireless control. In WO2006/039929, the wireless technology IR is used, which is limited by a short range and further has the disadvantage that the receiver transducer only can receive signals sent within a relatively narrow angle relative to the location of the receiver transducer. This means that the receiver transducer, in order to receive the signals from the wireless control in a satisfactory way, is located outside the control device and connected to this via a cable .

The use of wireless technology is mentioned in other publications of actuators and controls. As an example may be referred to DE 203 13 096 Ul to Dewert Antriebs- und Systemtechnik GmbH & Co., where a control is described, which mechanically via a wire transfers an operation signal to a control device. In the publication, it is incidentally mentioned that it might also be wireless technology like e.g. audible signals, optical or electromagnetic signals. As another example may be mentioned DE 91 03 817 Ul to Dewert Antriebs- und Systemtechnik GmbH & Co. , which relates to a lifting arrangement for rotatable or pivoting parts of furniture, where it also incidentally is mentioned that a remote control possibility may be imagined, which either uses infrared light or radio signals .

As it appears from the publications, the mention is only sporadic and immediately there is no indication that these remote controls have been realized in commercial products. Further, there is no technical direction, which would make it possible for a person skilled in the art to put these into practice.

The purpose of the invention is to provide a solution to the outlined problem, i.e. to structure an actuator system where the number of cables between the separate components in the actuator system is minimized in order both to make the construction simpler and more inexpensive, but also to avoid cables, which may be troublesome in connection with the movement of the application or cleaning of this. Moreover, a larger flexibility is desired in connection with the adjustment of the actuator system relative to the controls mentioned under the prior art . Here is thought both in terms of range but also direction finding and freedom for cables.

This is achieved according to the invention in that the actuator system is designed as stated in claim 1, where the power supply and the control device are arranged in connection with the actuator and located in a mutual housing and that the control device is equipped with a wireless interface, preferably based on radio signals, likewise located in the housing.

In this way, the cables between the separate components in the actuator system may be eliminated in that the connection between the electric motor in the actuator, the control device and the power supply is conducted internally in the housing, and where most of the

connection may be constructed on a printed circuit board. Further, the control is equipped with a wireless interface, which enables the adjustment of the actuator system to be performed via a wireless control. The fact that the wireless technology being used is based on radio signals (electromagnetic signals) solves the previous problems in terms of sufficient range and direction finding. In this way, the cable between the control device and the control is eliminated. The only cable left is thus the cable connecting the application to the mains power supply.

The invention is particularly simple in that the wireless interface is constructed in connection with the control. This may e.g. be performed in that the electronic circuits are designed on a shared printed circuit board mounted in the housing. However, there is no reason why the wireless interface could not be embodied completely or partially outside this printed circuit board e.g. on other printed circuit boards associated with the printed circuit board for the control device but which are still arranged in the housing. As the power supply both consists of a transformer and a regulator, the electronic components, which forms part of the regulation circuit may practically be placed on the same printed circuit board as the control device and the wireless interface . This does not preclude that the transformer for the power supply likewise may be positioned on the printed circuit board. In this way solutions may be provided, which in connection with a printed circuit board completely or partially assembles the power supply, the control device and the wireless interface, which result in great

advantages in connection with the manufacturing of the actuator system.

If the application is a mobile unit, like e.g. a patient lift or hospital bed, which is powered by a battery, the battery may be arranged in connection with the housing, so that the cable for the mains power supply is only connected when the battery needs charging.

If the actuator system includes more actuators, e.g. two, the housing may be oblong, where an actuator is located at each end of the housing, where the printed circuit board with the control device preferably may be located centrally in the housing.

The wireless interface can connect the control device to a wireless unit. As mentioned above, it might be a control for adjusting the actuator system, but other wireless units are foreseen. A wireless control may be a dedicated unit, which only functions in connection with the application concerned or more given applications. The application may likewise be constructed so that the control device only accepts operation from one or more dedicated controls.

A wireless unit, however, is not necessarily limited to a control of the hand-held type described above, but may also be a unit in the form of a computer with a wireless connection. Such a computer may be installed in connection with the application, or may be a stationary or mobile computer, e.g. a laptop for which it applies that it is equipped with a wireless interface matching the wireless interface in connection with the control

device . Such a computer may both be used by the user of the application for adjusting the actuator system, but also by e.g. service personnel for extracting data from the control device in preparation for monitoring or controlling the use and state of the application.

As regards hand-held computers such as PDAs and mobile phones, these may of course also be connected to the control via the wireless interface, if these are equipped with an interface matching the wireless interface. Further, the wireless unit should be equipped with a user interface, so that this appears as a control or system monitor, depending on which function the wireless unit should handle .

The communication between the wireless interface and the wireless unit takes place via defined commands listed in a protocol. The command from the wireless unit is build up in such a way that identification of transmitter and possibly receiver appears, and subsequently the desired action in the form of data. As regards the wireless interface, this may be adapted so that it more or less selectively can receive data from a wireless unit. Flexibly constructed, the wireless interface via software may be configured to be operated from all, one or a selection of wireless units based on the ID of the wireless unit. The configuration of the wireless interface may also be performed directly by means of a cabled interface for the control device or via training sequences, where the wireless units, which should be connected, are operated during the training period. In this way it would be possible for the wireless interface to receive the unique ID for a wireless unit, which

should be connected and store this ID internally for later approval of connected units .

In the same way, a wireless unit may have means for operating more wireless interfaces in that the unique codes for the various wireless interfaces are stored internally in the wireless unit and serve to address the wireless interfaces in a communication sequence. If the wireless interface and the wireless unit are equipped with means for duplex communication, the units may be bound to each other by a training sequence, where the units exchange their unique ID for later mutual approval .

In actuator systems, comprising a system for mains cut- off when the system is in a non active condition, where the system is not operated, (cf. e.g. WO 2007/107157 Al to Linak A/S and WO 95/23450 to Linak A/S) a particularly expedient mode of operation is conceived as part of the invention, where the wireless interface remains active, even though the system as such is not supplied with power. This is achieved in that the control device has an active condition and a sleep mode, where the power supply in the sleep mode is disengaged, but at regular intervals transfers energy pulses to an energy storage, which supplies the wireless interface with energy and that when the wireless interface receives a signal decodes so much of the signal that it can recognize a valid connection from a wireless unit and change the state of both the control device and the power supply to the state, where the control device and the power supply are active and then subsequently fully decodes the received signal and performs the desired operation of the actuator system for

then after a period without operation to enter the sleep mode again.

In connection with a reset function, which is typically activated by means of a switch, a double function may be constructed, which consists of both a function where the actuators are actuated to move the spindle nut to a predefined position, typically defined by a level or end stop switch, and a learning condition, where the wireless interface may be connected to one or more controls merely by activating these while the wireless interface is in the learning condition.

As it appears, the invention provides a solution to the outlined problem, which in a simple manner eliminates cables and provides a solution, which improves the range for a wireless control and that is even without the control having to point to a specific point in the application. The solution is also simple in that the wireless interface is integrated with the control device on the same printed circuit board or constructed in connection with the control device and the power supply, for which reason advantages are also obtained in connection with the manufacturing due to a more simple and inexpensive manufacturing process. Moreover, the solution is deeply integrated with the power cut-off device, which results in less power consumption, but still is a reliable mode of operation. In relation to the connection of controls, the solution is particularly simple in that the controls are approved for operation of the application by undergoing a training sequence, which comprises both the control device with the wireless

network and the wireless units, which are to be used with the application.

An actuator system according to the invention will be described more fully below with reference to the accompanying drawing, in which

fig. 1 shows a bed base shown with raised back rest and leg rest section, fig. 2 shows a perspective view of a first embodiment for the actuator system according to the invention, fig. 3 shows another embodiment of the actuator system where the bottom cover has been removed, fig. 4 shows a drawing of a wired control, fig. 5 shows a drawing of a wireless control, fig. 6 shows a block diagram of a wireless interface, and fig. 7 shows a diagram of the communication between a wireless interface and a wireless unit.

As it appears from fig. 1 of the drawing, showing a bed base for an adjustable bed, the bed base comprises a frame 1, in which is embedded a back rest section 2 and an articulated leg rest section 3. For the leg rest section 2 is embedded a transverse shaft 4 in the frame, on which a short arm 5 is secured. On each end of the shaft 4 is mounted a rod 6 connected to the back rest section 2. Correspondingly, it applies to the leg rest section 3 that this may be adjusted by rotating a shaft 7 , via a short arm 8 secured thereto . The movement of the back rest and leg rest sections 2,3 is performed by means of a dual actuator as shown in fig. 2. The actuator

comprises a mutual housing 9 with an cover 10 at each end that can be opened and which provides free access for a traverse shaft opening 11, through which the shafts 4, 6 may be lead.

As it appears from fig. 3, drive units in the form of linear actuators are located at each end of the housing 9. The actuators comprise a spindle 12 driven by a low- voltage DC-motor 13 through a worm gear 14. A spindle nut 15 constructed as a square block functions as a sliding element and is located on the spindle 12 and guided in the housing 9 of the actuator, so that it is prevented from rotating and may be moved back and forth on the spindle 12 depending on the direction of rotation of this. In the application, which here is an adjustable bed, the spindle nut 15 may thus be brought to move the shafts 4, 7 and move e.g. the back rest or leg rest section 2, 3 in the bed.

In the middle of the housing 9 a power supply based on a ring-core transformer 16 and a printed circuit board 17 is mounted, which comprises the electronics for both the power supply and the control device. In connection with the printed circuit board 17, sockets 18 for the plugs are mounted, where plugs may be inserted into as these are lead through lead-ins in the housing 9 for that purpose. The sockets 18 comprise a mains supply socket, but also sockets for a cabled control 19. The control, which is connected to the socket, may be a conventional mechanical contact-based control or a more intelligent unit, which functions as a wireless receiver for a wireless control. The solution, however, includes cables, for which reason a particularly expedient embodiment is

designed where the control device on the printed circuit board 17 is expanded with a wireless interface 20, which has means for directly communicating with a wireless unit, e.g. a wireless control 21. This results in great advantages as the wireless interface is supplied directly from the power supply and is deeply integrated also with the control device, so that the sleep mode of the control device, in order to save power by disengaging the power supply, is supported and the wireless interface remains active, even though the system as such is not supplied with power. This is achieved in that the control device has an active condition and a sleep mode, where the power supply in the sleep mode is disengaged, but at regular intervals transfers energy pulses to an energy storage, which supplies the wireless interface with energy and that, when the wireless interface receives a signal, decodes so much of the signal that it can recognize a valid connection from a wireless unit and change the state of both the control device and the power supply to the state, where the control device and the power supply are active and then subsequently fully decodes the received signal and performs the desired operation of the actuator system for after a period without operation to enter the sleep mode again.

The wireless receiver is constructed as a "super regenerative receiver" and shown as a block diagram in fig. 6. The receiver is based on a resonant circuit (L and C) tuned to the desired reception frequency, e.g. 433,92 MHz. The RF-signal is transmitted from a suitable antenna into the resonant circuit (this is not shown in the diagram) . The component G illustrates the loss in the resonant circuit (there are no LC circuits with an

infinitely high Q) . An amplifier is represented by the -g component, said amplifier is capable of creating a negative impedance, which is lower than G and thus create an oscillator together with the resonant circuit. A monostable oscillator is designed to activate and close the connection regularly with a time interval of a microsecond. When the connection is closed, the amplitude of the RF-signal is sampled and an oscillation initiates its accumulation. After a while the amplitude of the signal reaches a threshold due to the oscillation, which is detected by the comparator and the connection is broken again. The pulse width of the switch will drop concurrently with that the amplitude of the RF-signal rises. Thus, the pulse width corresponds to the demodulated RF-signal, which contains the transmitted piece of information.

The communication^ of information between a wireless transmitter and the wireless receiver follows the specifications in a protocol as explained in fig. 7, where it appears that three pulse trains are transmitted from a control with a pause of one millisecond between the pulse trains. A new series of pulse trains may be transmitted with an interval of one hundred and sixty milliseconds. A pulse train consists in principle of a unique identification code for the control followed by data, which in all essentials consists of instructions for the control device about which function should be activated. This means that an activation of a key will result in that pulses are continuously transmitted to the control device, which will then continue to perform the desired function until the key is no longer activated or the position of the spindle nut in the linear actuator

has reached an end position. As an extra security, checksum calculation on more levels is incorporated in the protocol, thus both in connection with the unique identifier and data. The Id-checksum is included in order for the wireless interface quickly and with minimum power consumption to determine if the wireless signal is from a control approved for operating the actuator system. The pulse train consists of a preamble and a header, which both indicates the beginning of a new pulse train and synchronizes the wireless interface to receive the pulse train. The counter "counter" is incremented for every pulse train transmitted of the type concerned. If the type is changed, the counter is reset. The field "Type" describes the type and the length of the data field, so that the wireless interface is capable of separating this variable data field from the pulse train.

The control, or if desired more controls, is connected to the wireless interface in that a training sequence is completed. In praxis this occurs in that a reset button 22, on the housing 9 next to the sockets 18 for the plugs, is pushed e.g. with a ball pen or the like. If both actuators in the actuator system have reached an end stop in the direction where a bed would appear as a horizontal surface, the control device will enter into a state where it is capable of connecting to a wireless remote control 21. The wireless interface will during this period register the unique addresses of the controls, which are activated, in preparation for later recognition of these and only allow operation of the actuator system via these or by a cabled control mounted in parallel. If the reset button 22 is pushed, while the bed is not in its horizontal position, a driving of the

actuators is initiated, which brings the bed to the horizontal lowered position, after which the reset button 22 may be pushed again for completing the training sequence in preparation for connection one or more controls to the actuator system.

Even though the example describes an embodiment of the invention based on an adjustable bed, the invention may also be carried out in connection with other articles of furniture, e.g. an adjustable chair, in which various adjustment possibilities and functions may be incorporated. Another use may be in a piece of furniture for a monitor or a flat screen TV, where the screen, when it is not being used, may be slit into the piece of furniture and thus be protected. In adjustable tables, an execution of the invention would also be advantageous, as cables thus can be avoided and provide both a simpler construction and mounting and a more aesthetic look.