Abstract:
A control system is described for controlling an appliance, such as a fan. The control system includes a user-operable remote control for transmitting light signals, a control circuit for controlling at least one component of the appliance, such as a motor, and a user interface circuit for supplying control signals to the control circuit. The user interface circuit includes a switch and a receiver for receiving light signals transmitted by the remote control. A push button actuator both actuates the switch through movement of the actuator towards the switch, and conveys light signals received from the remote control to the receiver.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of United Kingdom Application No. 1223092.6, filed 20 Dec. 2012, the entire contents of which are incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The present invention relates to a control system for controlling an appliance. Particularly, but not exclusively, the present invention relates to a control system for controlling a floor-standing or table-top fan, such as a desk, tower or pedestal fan, a fan heater, an air purifier or a humidifier. The present invention is not restricted to use in controlling a fan, and so may be used to control other appliances which use both a remote control and a push button or other moveable form of actuator to control an operational state or setting of the appliance. 
       BACKGROUND OF THE INVENTION 
       [0003]    A conventional domestic fan typically includes a set of blades or vanes mounted for rotation about an axis, and drive apparatus for rotating the set of blades to generate an air flow. The movement and circulation of the air flow creates a ‘wind chill’ or breeze and, as a result, the user experiences a cooling effect as heat is dissipated through convection and evaporation. The blades may be located within a cage or other housing which allows an air flow to pass through the housing while preventing users from coming into contact with the rotating blades during use of the fan. 
         [0004]    WO 2009/030879 describes a fan assembly which does not use caged blades to project air from the fan assembly. Instead, the fan assembly comprises a cylindrical base which houses a motor-driven impeller for drawing a primary air flow into the base, and an annular nozzle connected to the base and comprising an annular air outlet through which the primary air flow is emitted from the fan. The nozzle defines a central opening through which air in the local environment of the fan assembly is drawn by the primary air flow emitted from the mouth, amplifying the primary air flow. 
         [0005]    WO 2012/017219 also describes such a fan assembly. The base houses a user interface for enabling a user to control various operational states of the fan assembly. The user interface comprises a plurality of user-operable buttons, a display, and a user interface control circuit connected to the buttons and the display. The user interface control circuit has a sensor for receiving signals from a remote control. The sensor is located behind a window provided on the base. The display is located within the body, and is arranged to illuminate the inner surface of the body. The body is formed from a translucent plastics material which allows the display to be seen by a user. In response to operation of the buttons and the remote control, the user interface control circuit transmits appropriate signals to the main control circuit to control various operations of the fan assembly. These include the activation and de-activation of the motor, the rotational speed of the motor, and the activation and de-activation of an oscillating mechanism for oscillating a lower part of the base relative to an upper part of the base. A separate button is provided on each of the base and the remote control to allow the user to control each of these operations. 
       SUMMARY OF THE INVENTION 
       [0006]    In a first aspect, the present invention provides a control system for controlling an appliance, the control system comprising:
       a remote control for transmitting light signals;   a control circuit for controlling at least one component of the appliance;   a user interface circuit for supplying control signals to the control circuit, the user interface circuit comprising a switch and a receiver for receiving light signals transmitted by the remote control; and   an actuator, preferably a push button actuator, for actuating the switch through movement of the actuator towards the switch, and for conveying light signals received from the remote control to the receiver.       
 
         [0011]    The actuator thus performs the dual function of actuating the switch, preferably in response to a user pushing the actuator towards the switch, and transferring to the receiver light signals which have been transmitted by the remote control and which are incident upon the actuator. This dual function of the actuator can allow the appliance to be provided without a dedicated window or other dedicated light transmissive component for conveying the signals transmitted by the remote control to the receiver, thereby reducing manufacturing costs. As there is no requirement to locate the receiver immediately behind a window provided on an external surface of the appliance, the receiver may be disposed in a more convenient location within the appliance, with the actuator shaped as required to convey signals to the receiver. For example, the receiver may be located adjacent to or alongside the switch to reduce the size of a printed circuit board upon which the components of the user interface circuit are mounted. Alternatively, the switch and the receiver may be located on opposite sides of the printed circuit board. 
         [0012]    As mentioned above, the actuator is preferably a push button actuator which may be pressed by the user to contact the switch to change an operational mode, state or setting of the appliance. Alternatively, the actuator may be in the form of a slidable actuator, a rotatable actuator or dial. An advantage of providing the actuator in the form of a push button actuator is that a light path for conveying the light signals to the receiver can be maintained irrespective of the current position of the actuator relative to the switch. 
         [0013]    The actuator may comprise a light guide or a light pipe formed in or otherwise carried by the actuator. In a preferred example, a part of the actuator is formed from light transmissive material to provide a path for conveying light signals received from the remote control to the receiver. This part of the actuator is preferably a moulded section of the actuator, and may be formed using an injection moulding technique. This can allow the section of the actuator to be readily formed to the desired shape for conveying the light signals to the receiver. 
         [0014]    This part of the actuator preferably extends between a first surface which is exposed to light signals transmitted by the remote control, and a second surface which is located adjacent to the receiver. This first surface may be a surface which is engageable by a user to move the actuator towards the switch, and so conveniently this may be provided by a front surface of the actuator which is pushed by a user to actuate the switch. The second surface is preferably substantially parallel to the first surface, and may be provided by a rear surface of the actuator. The actuator is preferably moveable relative to the switch in a direction which is substantially perpendicular to the first surface. 
         [0015]    The light signals transmitted by the remote control are preferably infrared light signals, and so this part of the actuator which conveys the light signals to the receiver is preferably formed from material which is transmissive of infrared light. One suitable example is polycarbonate material. 
         [0016]    The actuator may comprise a single component formed from material which is transmissive of light having a wavelength which is the same as the wavelength of the light signals transmitted by the remote control. Alternatively, the actuator may be formed from a plurality of parts, sections or components which are joined or otherwise connected together, with at least one of these parts being formed from such light transmissive material. The other part(s) of the actuator may be formed from material which is opaque, or otherwise not so transmissive of light having a wavelength which is the same as the wavelength of the light signals transmitted by the remote control. This can create a discrete path for the passage of the light signals through the actuator to ensure that the light signals reach the receiver with an intensity which is sufficient for the light signals to be reliably detected at the receiver. 
         [0017]    The user interface circuit is preferably arranged to transmit a signal to the control circuit which is indicative of the actuation of the switch. The user interface circuit may also advise the control circuit of de-actuation of the switch. The control circuit is preferably arranged to control an operational state or setting of the appliance in accordance with the signal received from the user interface circuit. 
         [0018]    The user interface circuit may comprise a light emitting device for illuminating the actuator depending on the operational state or setting of the appliance. This is preferably the same operational state or setting which is controlled through actuation of the switch by the actuator. For example, the light emitting device may illuminate the actuator when the appliance is in an “on” state. Where the appliance is in the form of a fan, which term includes desk, tower and pedestal fans, fan heaters, air purifiers and humidifiers, the light emitting device may illuminate the actuator when a motor of a fan is in an “on” state to generate an air flow. 
         [0019]    The light emitting device is preferably a light emitting diode (LED). The LED is preferably arranged to illuminate a third surface of the actuator which is spaced from the second surface of the actuator. The third surface is preferably parallel to the first surface, and may be provided by a rear surface of the actuator. The part of the actuator which conveys the light signals transmitted by the remote control to the receiver may also be arranged to convey the light emitted by the LED to a surface of the actuator which is visible to the user during use of the appliance. This may be the first surface of the actuator, or it may be a fourth surface of the actuator which is spaced from the first surface. The fourth surface may be contiguous with the first surface. 
         [0020]    As an alternative to using this one part of the actuator to convey both the light signals received from the remote control to the receiver and the light signals received from the LED to an external surface of the actuator, the actuator may be provided with a first light conveying means for conveying light signals received from the remote control to the sensor, and a second light conveying means for conveying light emitted by the LED to an external surface of the actuator. 
         [0021]    In a second aspect the present invention provides a control system for controlling an operational state of an appliance, the control system comprising:
       a remote control for transmitting light signals;   a control circuit for controlling at least one component of the appliance;   a user interface circuit for supplying control signals to the control circuit, the user interface circuit comprising a switch, a receiver for receiving light signals transmitted by the remote control, and a light emitting device for indicating the operational state of the appliance; and   an actuator for actuating the switch through movement of the actuator towards the switch, the actuator comprising light conveying means for conveying light signals received from the remote control to the sensor, and for conveying light emitted by the light emitting device to an external surface of the actuator.       
 
         [0026]    The second light conveying means may have a lower infrared transmittance than the first light conveying means. The first light conveying means may have a lower visible light transmittance than the second light conveying means. 
         [0027]    These two light conveying means may be provided by separate components of the actuator. Each light conveying means may be provided by a respective light guide or light pipe. Alternatively, only one of the light conveying means may be provided by a light guide or light pipe, with the other light conveying means being provided by a moulded part of the actuator. As another alternative, each light conveying means may be provided by a respective moulded part of the actuator. These moulded parts may be formed from different light transmissive materials. As a further alternative, these moulded parts may be formed from the same light transmissive materials, and so these parts may be integral with each other, or they may be otherwise joined together. The parts may have any desired configuration. For example, the parts may be arranged side by side, or one part may at least partially surround the other part. 
         [0028]    In a preferred embodiment, the actuator comprises a single component which is arranged to convey infrared light signals from a first, external surface of the actuator to a second, internal surface located adjacent to the receiver, and to convey visible light signals to the external surface of the actuator from a third, internal surface located adjacent to the light emitting device. 
         [0029]    The actuator is preferably biased away from the switch. For example, a spring or other resilient member may engage the actuator to urge the actuator away from the switch. The resilient member may be located between the actuator and the printed circuit board, or it may be located between the actuator and a structural part of the appliance. The structural part of the appliance may be connected to an outer wall of the appliance, or it may be connected to a frame or other member for supporting the printed circuit board within the appliance. As an alternative to providing a separate resilient member for urging the actuator away from the switch, the actuator may comprise one or more resilient arms which normally engage a wall or other structural part of the appliance. When the actuator is moved towards the switch, the arms deform elastically to generate internal forces which, when the actuator is released by the user, urge the actuator away from the switch as the arms relax. 
         [0030]    The user interface circuit may include a display for displaying information relating to an operational state of the appliance. The display is preferably mounted on the printed circuit board, and the actuator is preferably located beneath the display. 
         [0031]    The control circuit is preferably arranged to change an operational state or setting of the appliance in response to the actuation of the switch by the user. The appliance may be any electrical appliance which has an operational state or setting which may be controlled using both an actuator provided on the appliance and a remote control. In a described embodiment, the appliance is in the form of a fan, comprising an air inlet, an air outlet and a motor for rotating an impeller to generate an air flow from the air inlet to the air outlet. The operational state or setting of the fan may comprise one of the current rotational speed of the motor, the current activation state (on or off) of the motor, and the current activation state (on or off) of an oscillation mechanism for oscillating one part of the fan relative to another part of the fan. If the fan includes a heater, then the operational state or setting of the fan may comprise the current activation state (on or off) of the heater or a current temperature setting of the fan. 
         [0032]    The user interface circuit is preferably arranged to communicate the actuation of the switch to the control circuit. The control circuit is preferably in the form of a separate printed circuit board assembly. The control circuit preferably comprises a microcontroller or microprocessor unit, a power supply unit for receiving power from a power source, such as a mains power source, and a motor driver, preferably a brushless DC motor driver, for controlling the rotational speed of the motor. Where the fan includes an oscillation mechanism for oscillating part of the fan, for example the air outlet, relative to another part of the fan, for example the air inlet, the control circuit may also include oscillation motor control circuitry for driving the oscillation mechanism. 
         [0033]    The action taken by the control circuit in response to the actuation of the switch may depend on a current operational state or setting of the fan, and the action which is assigned to the actuation of the switch. For example, if the motor is currently activated so that the fan is in an “on” state, the control circuit may de-activate the motor in response to the actuation of the switch to place the fan in an “off” state. On the other hand, if the motor is currently de-activated so that the fan is in the “off” state, the control circuit may activate the motor in response to the actuation of the switch to place the fan in the “on” state. Thus, pressing the actuator may simply toggle the fan between the “on” and “off” states. The control circuit may instruct the user interface circuit to activate the LED when the fan is in the “on” state. 
         [0034]    Alternatively, if the oscillation mechanism is currently activated, the control circuit may de-activate the oscillation mechanism in response to the actuation of the switch. On the other hand, if the oscillation mechanism is currently de-activated, the control circuit may activate the oscillation mechanism in response to the actuation of the switch. Thus, pressing the actuator may simply toggle the oscillation mechanism between active and inactive states. 
         [0035]    Such a change in an operational state of the fan also may be effected by the user through use of the remote control. For example, when the user presses a specific “on/off” button of the remote control, the remote control transmits a unique infrared control signal which is received by the receiver of the user interface circuit. The user interface circuit communicates the receipt of this signal to the control circuit, in response to which the control circuit activates or de-activates the motor as appropriate. As another example, when the user presses a specific “oscillate” button of the remote control, the remote control transmits a different, unique infrared control signal which is received by the receiver of the user interface circuit. The user interface circuit communicates the receipt of this signal to the control circuit, in response to which the control circuit activates or de-activates the oscillation mechanism as appropriate. 
         [0036]    The fan may be configured so as to allow the user to select one of a number of different pre-defined speed settings for the rotational speed of the motor, and thus for the flow rate of the air emitted from the air outlet. The fan preferably comprises at least five different user selectable speed settings, and more preferably at least eight different user selectable speed settings. In a preferred example, the fan has ten different speed settings, and the user is able to select from setting “1” to setting “10”. Speed setting 1 may correspond to a relatively low rotational speed of the motor, whereas speed setting 10 may correspond to a relatively high rotational speed of the motor. The motor is preferably in the form of a DC motor to maximise the number of different speed settings which may be selected by the user. The number of the selected speed setting may be displayed on the display. The user may never be aware of the actual rotational speed of the motor, but aware only that selection of a higher rated speed setting increases the flow rate of air emitted from the fan. 
         [0037]    A change in the rotational speed of the motor also may be effected by the user through use of the remote control. For example, when the user presses a specific “speed up” button of the remote control, the remote control transmits a unique infrared control signal which is received by the receiver of the user interface circuit. The user interface circuit communicates the receipt of this signal to the control circuit, in response to which the control circuit increases the rotational speed of the motor to the speed associated with the next highest speed setting, and instructs the user interface circuit to display that speed setting on the display. If the user presses a specific “speed down” button of the remote control, the remote control transmits a different, unique infrared control signal which is received by the receiver of the user interface circuit. The user interface circuit communicates the receipt of this signal to the control circuit, in response to which the control circuit decreases the rotational speed of the motor to the speed associated with the next lowest speed setting, and instructs the user interface circuit to display that speed setting on the display. 
         [0038]    The user interface circuit may comprise one or more buttons or dials, or a touch sensitive screen, to allow the user to select the desired speed setting. In a preferred embodiment, the actuator is used both to change the operational (on/off) state of the motor and to change the rotational speed of the motor. The operation which is performed by the control circuit in response to the actuation of the switch may depend on the duration of the contact made between the actuator and the switch. For example, the control circuit may be configured to change the operational state of the motor, i.e. turn the motor on or off, when the duration of the contact made between the actuator and the switch is relatively short, or below a set value, and to change the rotational speed of the motor when the duration of the contact made between the actuator and the switch is relatively long, or above the set value. The set value may be in the range from 0.5 to 5 seconds, for example 1 second. 
         [0039]    When the duration of the contact between the switch and the actuator is above the set value, the control circuit may increase the rotational speed of the fan from the rotational speed associated with the current setting to the rotational speed associated with the next highest speed setting. If the user continues to depress the actuator against the switch, the control circuit may vary the rotational speed of the motor between a maximum rotational speed associated with the highest user selectable speed setting, and a minimum rotational speed associated with the lowest user selectable speed setting, until the user releases the actuator. 
         [0040]    In a third aspect the present invention provides a fan comprising:
       an air inlet;   an air outlet;   an impeller and a motor for rotating the impeller to draw air through the air inlet;   a control circuit for controlling the motor;   a remote control for transmitting light signals;   a user interface circuit for supplying control signals to the control circuit, the user interface circuit comprising a switch and a receiver for receiving light signals transmitted by the remote control; and   an actuator for actuating the switch through movement of the actuator towards the switch and for conveying light signals received from the remote control to the receiver.       
 
         [0048]    Features described above in connection with the first aspect of the invention are equally applicable to each of the second and third aspects of the invention, and vice versa. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0049]    Preferred features of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
           [0050]      FIG. 1  is a front view of a fan; 
           [0051]      FIG. 2  is a side sectional view of the fan; 
           [0052]      FIG. 3  is a front sectional view of the fan; 
           [0053]      FIG. 4(   a ) is a first perspective view, from below, of part of the upper base member of the fan, and  FIG. 4(   b ) is a second perspective view, from below, of part of the upper base member of the fan, 
           [0054]      FIG. 5(   a ) is a first perspective view, from below, of a user interface circuit of the fan, 
           [0055]      FIG. 5(   b ) is a second perspective view, from above, of the user interface circuit, and 
           [0056]      FIG. 5(   c ) is a third perspective view, from below, of the user interface circuit; 
           [0057]      FIG. 6(   a ) is a front view of the user interface circuit,  FIG. 6(   b ) is a sectional view taken along line D-D in  FIG. 6(   a ),  FIG. 6(   c ) is a top view of the user interface circuit, and  FIG. 6(   d ) is a bottom view of the user interface circuit; and 
           [0058]      FIG. 7  is a schematic illustration of components of the user interface circuit and a control circuit of the fan. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0059]      FIG. 1  is a front view of a fan assembly  10 . The fan assembly  10  comprises a body  12  having an air inlet  14  in the form of a plurality of apertures formed in the outer casing  16  of the body  12 , and through which a primary air flow is drawn into the body  12  from the external environment. An annular nozzle  18  having an air outlet  20  (shown in  FIG. 2 ) for emitting the primary air flow from the fan assembly  10  is connected to the upper end of the body  12 . The body  12  is mounted on a base  22  so as to allow the body  12  to tilt relative to the base  22 . The base  22  comprises a user-operable actuator  24  for allowing a user to control an operational state of the fan assembly  10 . The fan assembly  10  also includes a remote control  26  for allowing the user to control, remotely from the fan assembly  10 , operational states and settings of the fan assembly  10 . When not in use, the remote control  24  may be stored on the upper surface of the nozzle  18 , as illustrated in  FIG. 1 . 
         [0060]    The nozzle  18  has an annular shape. With reference also to  FIGS. 2 and 3 , the nozzle  18  comprises an outer wall  28  extending about an annular inner wall  30 . In this example, each of the walls  28 ,  30  is formed from a separate component. Each of the walls  28 ,  30  has a front end and a rear end. The rear end of the outer wall  28  curves inwardly towards the rear end of the inner wall  30  to define a rear end of the nozzle  18 . The front end of the inner wall  30  is folded outwardly towards the front end of the outer wall  28  to define a front end of the nozzle  18 . The front end of the outer wall  28  is inserted into a slot located at the front end of the inner wall  30 , and is connected to the inner wall  30  using an adhesive introduced to the slot. 
         [0061]    The inner wall  30  extends about an axis, or longitudinal axis, X to define a bore, or opening,  32  of the nozzle  18 . The bore  32  has a generally circular cross-section which varies in diameter along the axis X from the rear end of the nozzle  18  to the front end of the nozzle  18 . 
         [0062]    The inner wall  30  is shaped so that the external surface of the inner wall  30 , that is, the surface that defines the bore  32 , has a number of sections. The external surface of the inner wall  30  has a convex rear section  34 , an outwardly flared frusto-conical front section  36  and a cylindrical section  38  located between the rear section  34  and the front section  36 . 
         [0063]    The outer wall  28  comprises a base  40  which is connected to an open upper end of the body  12 , and which has an open lower end which provides an air inlet for receiving the primary air flow from the body  12 . The majority of the outer wall  28  is generally cylindrical in shape. The outer wall  28  extends about a central axis, or longitudinal axis, Y which is parallel to, but spaced from, the axis X. In other words, the outer wall  28  and the inner wall  30  are eccentric. In this example, the axis X is located above the axis Y, with each of the axes X, Y being located in a plane which extends vertically through the centre of the fan assembly  10 . 
         [0064]    The rear end of the outer wall  28  is shaped to overlap the rear end of the inner wall  30  to define the air outlet  20  of the nozzle  18  between the inner surface of the outer wall  28  and the outer surface of the inner wall  30 . The air outlet  20  is in the form of a generally circular slot centred on, and extending about, the axis X. The width of the slot is preferably substantially constant about the axis X, and is in the range from 0.5 to 5 mm The overlapping portions of the outer wall  28  and the inner wall  30  are substantially parallel, and are arranged to direct air over the convex rear section  34  of the inner wall  30 , which provides a Coanda surface of the nozzle  18 . 
         [0065]    The outer wall  28  and the inner wall  30  define an interior passage  42  for conveying air to the air outlet  20 . The interior passage  42  extends about the bore  32  of the nozzle  18 . In view of the eccentricity of the walls  28 ,  30  of the nozzle  18 , the cross-sectional area of the interior passage  42  varies about the bore  32 . The interior passage  42  may be considered to comprise first and second curved sections  44 ,  46  which each extend in opposite angular directions about the bore  32 . Each curved section  44 ,  46  of the interior passage  42  has a cross-sectional area which decreases in size about the bore  32 . 
         [0066]    The body  12  and the base  22  are preferably formed from plastics material. The body  12  and the base  22  preferably have substantially the same external diameter so that the external surface of the body  12  is substantially flush with the external surface of the base  22  when the body  12  is in an untilted position relative to the base  22 . 
         [0067]    The body  12  comprises the air inlet  14  through which the primary air flow enters the fan assembly  10 . In this example the air inlet  14  comprises an array of apertures formed in the section of the outer casing  16  of the body  12 . Alternatively, the air inlet  14  may comprise one or more grilles or meshes mounted within windows formed in the outer casing  16 . The body  12  is open at the upper end (as illustrated) for connection to the base  40  of the nozzle  18 , and to allow the primary air flow to be conveyed from the body  12  to the nozzle  18 . 
         [0068]    With reference also to  FIGS. 4 to 6 , the base  22  houses a user interface circuit  48 . The user interface circuit  48  comprises a number of components which are mounted on a printed circuit board  50 . The printed circuit board  50  is held in a frame  52  connected to the outer surface of the base  22 . The user interface circuit  48  comprises a sensor or receiver  54  for receiving signals transmitted by the remote control  26 . In this example, the signals emitted by the remote control  26  are infrared light signals. The remote control  26  is similar to the remote control described in WO 2011/055134, the contents of which are incorporated herein by reference. In overview, the remote control  26  comprises a plurality of buttons which are depressible by the user, and a control unit for generating and transmitting infrared light signals in response to depression of one of the buttons. The infrared light signals are emitted from a window located at one end of the remote control  26 . The control unit is powered by a battery located within a battery housing of the remote control  26 . 
         [0069]    The user interface control circuit  48  also comprises a switch  56  which is actuable by a user through operation of the actuator  24 . In this example, the actuator  24  is in the form of a push button actuator which has a front surface  58  can be pressed by a user to cause a rear surface  60  of the actuator  24  to contact the switch  56 . The front surface  58  of the actuator  24  is accessible through an aperture  62  formed in the outer surface of the base  22 . The actuator  24  is biased away from the switch  56  so that, when a user releases the actuator  24 , the rear surface  60  of the actuator  24  moves away from the switch  56  to break the contact between the actuator  24  and the switch  56 . In this example, the actuator  24  comprises a pair of resilient arms  64 ,  66 . The end of each arm  64 ,  66  is located adjacent to a respective internal wall  68 ,  70  of the base  22 . When a user presses the actuator  24 , the engagement between the ends of the arms  64 ,  66  and the walls  68 ,  70  causes the arms  64 ,  66  to deform elastically as the actuator  24  moves towards the switch  56 . When the user releases the actuator  24 , the arms  64 ,  66  relax so that the actuator  24  moves automatically away from the switch  56 . 
         [0070]    The actuator  24  also performs the function of transferring to the receiver  54  light signals which have been transmitted by the remote control  26  and which are incident upon the front surface  58  of the actuator  24 . In this example, the actuator  24  is a single moulded component which is formed from light transmissive material, for example a polycarbonate material. A second rear surface  72  of the actuator  24  is located adjacent to the receiver  54 , and so part of the actuator  24  which extends between the front surface  58  and this second rear surface  72  provides a path for the transmitted infrared light signals. 
         [0071]    The user interface circuit  48  further comprises a display  74  for displaying a current operational setting of the fan assembly  10 , and a light emitting diode (LED)  76  which is activated depending on a current operational state of the fan assembly  10 . The display  74  is preferably located immediately behind a relatively thin portion of the outer casing of the base  22  so that the display  74  is visible to the user through the outer casing of the base  22 . In this example, the LED  76  is activated when the fan assembly  10  is in an “on” state, in which an air flow is generated by the fan assembly  10 . In this example, the actuator  24  is also arranged to transfer light emitted by the LED  76  to the front surface  58  of the actuator  24 . The actuator  24  has a third rear surface  78  which is located adjacent to the LED  76 , and so part of the actuator  24  which extends between the front surface  58  and this third rear surface  72  provides a path for the light signals emitted by the LED  76 . The third rear surface  78  is spaced from the second rear surface  72 . 
         [0072]    The base  22  also houses a main control circuit, indicated generally at  80 , connected to the user interface circuit  48 . The main control circuit  80  comprises a microprocessor  82 , which is illustrated schematically in  FIG. 12 . The base  22  also houses a mechanism, indicated generally at  84 , for oscillating an upper section  86  of the base  22  relative to a lower section  88  of the base  22 . The main control circuit  80  comprises oscillation motor control circuitry  90  for driving the oscillation mechanism  84 . The operation of the oscillating mechanism  84  is controlled by the main control circuit  80  upon receipt of an appropriate control signal from the remote control  26 . The range of each oscillation cycle of the upper section  86  relative to the lower section  88  is preferably between 60° and 120°, and in this example is around 80°. In this example, the oscillating mechanism  84  is arranged to perform around 3 to 5 oscillation cycles per minute. A mains power cable  91  for supplying electrical power to the fan assembly  10  extends through an aperture formed in the lower section  88 . The cable  91  is connected to a plug (not shown). The main control circuit  80  comprises a power supply unit  92  connected to the cable  91 , and a supply voltage sensing circuit  94  for detecting the magnitude of the supply voltage. 
         [0073]    Returning to  FIGS. 2 and 3 , the body  12  comprises a duct  100  having a first end defining an air inlet  102  of the duct  100  and a second end located opposite to the first end and defining an air outlet  104  of the duct  100 . The duct  100  is aligned within the body  12  so that the longitudinal axis of the duct  100  is collinear with the longitudinal axis of the body  12 , and so that the air inlet  102  is located beneath the air outlet  104 . 
         [0074]    The duct  100  extends about an impeller  106  for drawing the primary air flow into the body  12  of the fan assembly  10 . The impeller  106  is a mixed flow impeller. The impeller  106  comprises a generally conical hub, a plurality of impeller blades connected to the hub, and a generally frusto-conical shroud connected to the blades so as to surround the hub and the blades. The blades are preferably integral with the hub, which is preferably formed from plastics material. 
         [0075]    The impeller  106  is connected to a rotary shaft  108  extending outwardly from a motor  110  for driving the impeller  106  to rotate about a rotational axis Z. The rotational axis Z is collinear with the longitudinal axis of the duct  100  and orthogonal to the axes X, Y. In this example, the motor  110  is a DC brushless motor having a speed which is variable by a brushless DC motor driver  112  of the main control circuit  80 . As described in more detail below, the user may adjust the speed of the motor using the actuator  24  or the remote control  26 . In this example, the user is able to select one of ten different speed settings, each corresponding to a respective rotational speed of the motor  110 . The number of the current speed setting is displayed on the display  74  as the speed setting is changed by the user. 
         [0076]    The motor  110  is housed within a motor housing. The outer wall of the duct  100  surrounds the motor housing, which provides an inner wall of the duct  100 . The walls of the duct  100  thus define an annular air flow path which extends through the duct  100 . The motor housing comprises a lower section  114  which supports the motor  110 , and an upper section  116  connected to the lower section  114 . The shaft  108  protrudes through an aperture formed in the lower section  114  of the motor housing to allow the impeller  106  to be connected to the shaft  108 . The motor  110  is inserted into the lower section  114  of the motor housing before the upper section  116  is connected to the lower section  114 . The lower section  114  of the motor housing is generally frusto-conical in shape, and tapers inwardly in a direction extending towards the air inlet  102  of the duct  100 . The upper section  116  of the motor housing is generally frusto-conical in shape, and tapers inwardly towards the air outlet  104  of the duct  100 . An annular diffuser  118  is located between the outer wall of the duct  100  and the upper section  116  of the motor housing. The diffuser  118  comprises a plurality of blades for guiding the air flow towards the air outlet  104  of the duct  100 . The shape of the blades is such that the air flow is also straightened as it passes through the diffuser  118 . A cable for conveying electrical power to the motor  110  passes through the outer wall of the duct  100 , the diffuser  118  and the upper section  116  of the motor housing. The upper section  116  of the motor housing is perforated, and the inner surface of the upper section  116  of the motor housing is lined with noise absorbing material  120 , preferably an acoustic foam material, to suppress broadband noise generated during operation of the fan assembly  10 . 
         [0077]    The duct  100  is mounted on an annular seat located within the body  12 . The seat extends radially inwardly from the inner surface of the outer casing  16  so that an upper surface of the seat is substantially orthogonal to the rotational axis Z of the impeller  106 . An annular seal  122  is located between the duct  100  and the seat. The annular seal  122  is preferably a foam annular seal, and is preferably formed from a closed cell foam material. The annular seal  122  has a lower surface which is in sealing engagement with the upper surface of the seat, and an upper surface which is in sealing engagement with the duct  100 . The seat comprises an aperture to enable the cable (not shown) to pass to the motor  110 . The annular seal  122  is shaped to define a recess to accommodate part of the cable. One or more grommets or other sealing members may be provided about the cable to inhibit the leakage of air through the aperture, and between the recess and the internal surface of the outer casing  16 . 
         [0078]    To operate the fan assembly  10  the user either presses the actuator  24  to actuate the switch  56 , or presses an “on/off” button of the remote control  26  to transmit an infrared light signal which passes through the actuator  24  to be received by the receiver  54  of the user interface circuit  48 . The user interface circuit  48  communicates this action to the main control circuit  80 , in response to which the main control circuit  80  starts to operate the motor  110 . The LED  76  is activated to illuminate the actuator  24 . The light signals emitted by the LED  76  are conveyed through the actuator  24  to illuminate the front surface  58  of the actuator  24 . 
         [0079]    The main control circuit  80  selects the rotational speed of the motor  110  from a range of values, as listed below. Each value is associated with a respective one of the user selectable speed settings. 
         [0000]    
       
         
               
               
               
             
               
               
               
             
           
               
                   
                   
               
               
                   
                 Speed setting 
                 Motor speed (rpm) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                   
                 10 
                 9000 
               
               
                   
                 9 
                 8530 
               
               
                   
                 8 
                 8065 
               
               
                   
                 7 
                 7600 
               
               
                   
                 6 
                 7135 
               
               
                   
                 5 
                 6670 
               
               
                   
                 4 
                 6200 
               
               
                   
                 3 
                 5735 
               
               
                   
                 2 
                 5265 
               
               
                   
                 1 
                 4800 
               
               
                   
                   
               
             
          
         
       
     
         [0080]    Initially, the speed setting which is selected by the main control circuit  80  corresponds to the speed setting which had been selected by the user when the fan assembly 10 was previously switched off. For example, if the user has selected speed setting 7, the motor  110  is rotated at 7,600 rpm, and the number “7” is displayed on the display  74 . 
         [0081]    The motor  110  rotates the impeller  106  causes a primary air flow to enter the body  12  through the air inlet  14 , and to pass to the air inlet  102  of the duct  100 . The air flow passes through the duct  100  and is guided by the shaped peripheral surface of the air outlet  104  of the duct  100  into the interior passage  42  of the nozzle  18 . Within the interior passage  42 , the primary air flow is divided into two air streams which pass in opposite angular directions around the bore  32  of the nozzle  18 , each within a respective section  44 ,  46  of the interior passage  42 . As the air streams pass through the interior passage  42 , air is emitted through the air outlet  20 . The emission of the primary air flow from the air outlet  20  causes a secondary air flow to be generated by the entrainment of air from the external environment, specifically from the region around the nozzle  18 . This secondary air flow combines with the primary air flow to produce a combined, or total, air flow, or air current, projected forward from the nozzle  18 . 
         [0082]    If the user has used the remote control  26  to switch on the fan assembly  10 , then the user may change the rotational speed of the motor  110  by pressing either a “speed up” button on the remote control  26 , or a “speed down” button on the remote control  26 . If the user presses the “speed up” button, the remote control  26  transmits a unique infrared control signal which is received by the receiver  54  of the user interface circuit  48 . The user interface circuit  48  communicates the receipt of this signal to the main control circuit  80 , in response to which the main control circuit  80  increases the rotational speed of the motor  110  to the speed associated with the next highest speed setting, and instructs the user interface circuit  48  to display that speed setting on the display  74 . If the user presses the “speed down” button of the remote control  26 , the remote control  26  transmits a different, unique infrared control signal which is received by the receiver  54  of the user interface circuit  48 . The user interface circuit  48  communicates the receipt of this signal to the main control circuit  80 , in response to which the main control circuit  80  decreases the rotational speed of the motor  110  to the speed associated with the next lowest speed setting, and instructs the user interface circuit  48  to display that speed setting on the display  74 . 
         [0083]    If the user has used to the actuator  24  to switch on the fan assembly  10 , then if the user releases the actuator  24  within a preset period of time, which is preferably in the range from 0.5 to 5 seconds and in this example is 1 second, the motor  110  continues to rotate at a speed associated with the currently selected speed setting. The release of the actuator  24  breaks the contact between the actuator  24  and the switch  56 , and this break in the contact of the switch  56  is communicated to the main control circuit  80 . However, if the user continues to press the actuator  24  against the switch  56  for a duration which exceeds this preset period of time, the main control circuit  80  starts to gradually increase the rotational speed of the motor  110  from the speed associated with currently selected speed setting up to the speed associated with the highest speed setting. In this example, the rotational speed of the motor  110  is increased each 0.5 second to the speed associated with the next highest speed setting. For instance, if the user had selected speed setting 7, after 1 second the speed of the motor  110  is increased to 8,065 rpm, and the number “8” is displayed on the display  74 . If the user continues to depress the actuator for a further 0.5 second, the speed of the motor  110  is increased to 8,530 rpm, and the number “9” is displayed on the display  74 . 
         [0084]    Once the highest speed setting “10” has been reached, and if the user continues to press the actuator  24  against the switch  56 , the main control circuit  80  starts to gradually decrease the rotational speed of the motor  110  from the speed associated with highest speed setting down to the speed associated with the lowest speed setting. If that speed is reached and the user has still not released the actuator  24 , the main control circuit  80  starts to gradually increase the rotational speed of the motor  110  from the speed associated with lowest speed setting up to the speed associated with the highest speed setting. This cyclical variation of the speed of the motor  110 , with the speed of the motor  110  being changed after every 0.5 second, continues until the user releases the actuator  24  to break the contact between the actuator  24  and the switch  56 . Once that contact has been broken, the current speed of the motor  110  is maintained. 
         [0085]    The user may switch off the fan assembly  10  by pressing the “on/off” button of the remote control  26 . The remote control  26  transmits an infrared control signal which is received by the receiver  54  of the user interface circuit  48 . The user interface circuit  48  communicates the receipt of this signal to the main control circuit  80 , in response to which the main control circuit  80  de-activates the motor  110  and the LED  76 . The user may also switch off the fan assembly  10  by pressing the actuator  24  against the switch  56 . If the user releases the actuator  24  within the preset period of time, the user interface circuit  48  communicates this to the main control circuit  80 , in response to which the main control circuit  80  de-activates the motor  110  and the LED  76 . However, if the user does not release the actuator  24  within the preset period of time, the cyclical variation in the speed of the motor  110  is restarted, and continues until the user releases the actuator  24 .