the present invention will be described with respect to a flow generator ( fg ) for providing air or other breathable gas to a patient , for example a servo controlled blower for cpap treatment of sleep disordered breathing ( sdb ). the flow generator may be part of a respiratory treatment device 102 that may include some or all of the components illustrated in fig1 and 2 . for example , the respiratory treatment device will typically include a flow generator such as a servo - controlled blower 104 . the blower 104 will typically include an air inlet and impeller driven by a motor ( not shown ). optionally , the air inlet may be coupled with a gas supply , such as for oxygen , to mix with or supplement the breathable gas supplied by the impeller to the airway of a user . moreover , an air filter 103 may be provided , such as a hepa filter , to remove dust or other allergens from the air drawn into the air inlet . the blower may optionally be configured for generating varied flows or varied pressures associated with a patient respiratory cycle depending on the type of treatment ( e . g ., continuous level , bi - level , varying level etc . such as a pressure in an example range of 4 to 15 cmh2o or 4 to 25 cmh2o ) and it may further be adjusted based on respiratory conditions ( e . g ., apnea , hypopnea , obstruction , etc .) detected by the apparatus ( e . g ., apnea , hypopnea , obstruction , etc .). the respiratory treatment device 102 will also typically include a patient interface such as a flow delivery conduit 106 and nasal prongs or nasal cannula 108 to carry the flow of air or breathable gas to the upper airway of a user of the device or patient . the blower 104 can be coupled with the air delivery conduit 106 and the nasal cannula 108 so as to provide the breathable gas from the blower 104 . optionally , the patient interface may include a mask ( not shown ) coupled with the delivery conduit . operation of the respiratory treatment delivery apparatus may be controlled by one or more controller or processors 120 , which may be for example a digital microprocessor . the controller 120 receives signals supplied from various sensors , such as those described in more detail below , and applies a control logic to control the functions of the device , for example to control the operation of the blower 104 and of the humidifier heater 111 . the controller or processor 120 is typically configured and adapted to implement particular control . thus , the controller may include integrated chips , a memory and / or processor control instructions or data in an information storage medium . for example , programmed instructions encompassing such a control methodology may be coded on integrated chips in the circuits or memory of the device or such instructions may be loaded as software or firmware using an appropriate medium . the sensors may include one or more pressure sensors 114 , 131 such as a pressure transducer . the pressure sensor 114 can be configured to measure the pressure generated by the blower 104 and / or supplied at the nasal cannula or patient airway . in the illustrated embodiment , the pressure sensor 114 is proximate to the blower 104 . an additional or alternative pressure sensor 131 may be located downstream of the blower such as in the patient interface . the pressure sensor generates a pressure signal p ( t ) indicative of the measurements of pressure at its particular location . in some embodiments , the respiratory treatment delivery device may optionally include one or more flow sensors 116 . for example , flow through the nasal cannula 112 may be measured using a pneumotachograph and differential pressure transducer or similar device such as one employing a bundle of tubes or ducts to derive a flow signal f ( t ). although the flow sensor is illustrated in fig1 in a location proximate to the blower , the flow sensor may optionally be located closer to the patient , such as in the patient interface or nasal cannula 108 . optionally , the patient interface and / or blower may also include accessory devices for patient comfort such as a humidifier 112 and humidifier heater 111 . the humidifier device may be configured or controlled to heat and / or humidify the breathable gas to a desired temperature and / or humidity . for example , the device may include a reservoir or fluid circuit for passing the breathable gas through or proximate with a fluid or vapour of the reservoir or fluid circuit . the heater 111 may include one or more heating elements and / or heating plates to heat the fluid to create the vapour additional accessory devices may also be implemented with the respiratory treatment device . for example , a heater or heating element ( s ) such as a delivery tube heater 135 may optionally be provided in or on the delivery tube of the patient interface to assist in maintaining the temperature of the breathable gas after it passes from the humidifier or flow generator . for purposes of regulating the temperature and / or humidity of the breathable gas with the heating elements , the apparatus may also include one or more humidity sensors 117 , 121 , 136 and / or one or more temperature sensors 115 , 118 , 119 , 132 . the sensors generate temperature or humidity signals ( illustrated as t ( t ) and h ( t ) in fig1 ) for controlling or setting temperature and / or humidity of the comfort devices . optionally , some of the sensors may be located for measuring ambient conditions . thus , these sensors would be located away from the heaters and humidifier chamber so as to provide a more accurate reading of ambient conditions . the controller or processor 120 also communicates with a user interface of the device which includes control inputs such as buttons , dials for user control of the device , and a display such as a screen and / or indicator lights for indicating the device status and displaying control menus and the like to help the user select and control operations of the device . in some embodiments , some or all of the functions of the display and the user controls may be combined , for example by incorporating a touch screen display . the embodiments of the invention will be further described with reference to preferred modes of operation as defined below : mask fitting mode : when the fg provides a set pressure that allows the user to check for leaks between the mask & amp ; face , and to adjust the fit of the mask to minimise them . run mode : then fg is delivering pressure for the purpose of therapy ( includes pressure ramping ). error mode : when the fg has detected an error and is currently not delivering therapy . the following user interface ( ui ) states of operation are referred to : no power state : when the system has no mains power connected — either no power cord , a power cord with wall socket switched off , or a loss of mains power . power save state : when the start / stop key has been pushed and held for over 3 seconds , and the ut has been switched off except for the dim green led backlight of the start / stop button . setup state : when a user is interacting with the ui controls and the fg is in standby mode . note : this is always the first state that the ui comes to when the power is connected . adjust state : when a user is interacting with the ui controls and the fg is in run mode warming up state : when a user has activated the warm up function to pre - heat the humidifier ( and heated tube ) to the set value . the warming up state shall preferably be able to be stopped by selecting the warming up bar with the push button dial and pressing the dial to stop the warming up . the warming up function shall preferably only be available when the humidifier or climate control setting is greater than zero , however the warming up state will warm up both the humidifier and the heated tube to their set levels . warming ready state : when the humidifier and heated tube have reached their settings and the system is ready for use . the system stays in this state until a 30 minute time out is reached ( taken from the start of warming up ). the warming ready state shall be able to be stopped by selecting the warming ready bar with the push button dial and pressing the dial to stop the warming ready state . cool down state : when the humidifier and heated tube have been in use during the warming up state , warming ready state , or run mode , and the mode is changed to standby mode ( eg pushing the start / stop button during run mode , or stopping the warm up function ). this state is maintained for a duration that allows the humidifier to cool down . the purpose of this state is to minimise condensation build up in the system . idle state : when the user has not touched the controls for 2 minutes during standby mode , the ui shall “ rest ” with only the start / stop button illuminated and the lcd backlight faded to dim so that it is still readable . preferably this does not apply to the warming ready or cool down states . sleep state : when the user has not touched the controls for 2 minutes during run mode , the ui shall go to “ sleep ” with only the start / stop button illuminated . preferably this does not apply to the mask fit or error states . mask fit standby state : used when mask fit mode is activated from the standby mode by pushing and holding the dial . if the user does not push anything , this state will time out after 3 minutes and will automatically bring the device to the run mode in the adjust state . mask fit run state : used when mask fit mode is activated from the run mode by pushing and holding the dial . this is predominantly for patients , who wish to perform a mask fit , but have inadvertently activated run mode via smartstart when putting on their mask . if the user does not push anything , this state will time out after 3 minutes and will automatically bring the device back to run mode in the adjust state . alert state : therapy continues and the ui displays an alert message over the menu page on the lcd and flashes a bright blue led to indicate the alert state . note : if the user alert has been disabled , the message will still appear but the led will not flash . the alert message and led can be cleared by fixing the issue that caused the alert or they can be temporarily cleared when any key is pressed and normal navigation is resumed . if the issue that caused the alert is not fixed then the alert message will re - appear after a time out period . two further states are specified — a patient menu state and a clinical menu state . in the clinical menu state , additional parameters are displayed and controllable when compared to the patient menu state . in addition , the parameters that are displayed and controllable in the patient menu are determined from the clinical menu . for example , a clinician may decide that certain menus are available to one patient , and a different set of menus should be available for a different patient . in addition , the clinician can decide what information shall be displayed for the patient during or after treatment . for example , the clinician may decide whether to display such information as a “ sleep quality indicator ” to the patient , and whether to display an apnea hypopnea index ( ahi ). while various preferred time intervals are specified , in other forms , other time intervals may be used . in one embodiment a user interface according the present technology , comprises : a start / stop button a display ( preferably a colour display ) two menu keys ( preferably an information key and a setup key ); & amp ; a push - button dial . an example of a user interface 300 is shown in fig3 , which includes a display 302 , such as an lcd window or other suitable display for display of text and / or graphical information to the user , a start / stop ( or on / off ) button 304 at one side of the display for press control by the user , and a push - button dial 306 which incorporates both rotary dial and push button controls . in addition , there are push button controls 308 , 310 at the side edge of the display , for example an information ( or “ info ”) key 308 denoted by the standard “ i ” symbol and a setup key 310 denoted by two tick symbols . the illustrated display includes at its top a menu title 312 , below that has a menu page 314 for displaying menu information to the user , and has a series of menu tabs 316 along one side of the menu page for tabbing through different menu pages . in one form , the user interface further comprises a humidifier indicator light . schematic diagrams of electrical circuits suitable for implementing embodiments of the present technology are shown in fig4 to fig7 : fig4 shows a schematic of the components relating to the start / stop buttons . fig5 shows a schematic of the components relating to the lcd display . fig6 shows a schematic of the components relating to the push - button dial . fig7 shows a schematic of the components relating to the menu keys . in one embodiment , a control scheme for the present device comprises three main screens : each main screen displays at least one parameter . where there is more than one parameter , turning the dial leads to each included parameter being highlighted in turn . whilst a parameter is highlighted , it may be selected by pressing the dial . parameter adjustments may be made by rotating the dial . parameter adjustments may be confirmed by pressing the dial . preferably the home screen is the default screen that is displayed when the device is in standby mode or run mode . pressing the start / stop button 306 will adjust the device between the standby mode and the run mode . pressing once on the first push button control 308 results in the information screen being displayed . pressing a second time on the first push button control 308 results in a return to the home screen . pressing once on the second push button control 310 results in the setup screen being displayed . pressing a second time on the second push button control 310 results in a return to the home screen . in one form , the home screen displays information about a current patient treatment session when the device is in run mode . from the home screen , selecting the information menu key 308 once results in display of parameters defining the current treatment session , for example , the cpap pressure . selecting the information key once again , results in a return to the home screen . from the home screen , selecting the settings menu key 310 once results in display of parameters that may be adjustable , for example the mask setting . selecting the settings key 310 once again results in a return to the home screen . the control scheme of the present device facilitates rapid navigation and display of patient treatment information , as well as facilitating adjustment of parameters where appropriate . preferably the display is 220 pixels × 176 pixels , or larger . preferably the display can show colours . when starting run mode in the patient menu — the display will change from the current display to a default screen . if the humidifier is connected , or climate control is enabled , then the screen will default to the humidifier or climate control setting so that if the patient needs to adjust the humidification during the night , they do not have to navigate anywhere , and they can simply reach over , turn the dial ( which has highly tactile indents ) and easily adjust their humidification level without looking . in a preferred form the start / stop button 306 , the display 302 and the humidifier indicator include backlighting . in a preferred form , certain colours are used : green , blue and orange are used . however other colours may be used . when a light changes state , the transition may be gradual , for example , over 3 seconds . in other forms , the transition may be more rapid , or slower , or instantaneous . in one embodiment , operation of the backlighting of the start / stop button 306 is used to provide the user with information on the device status , as described below . preferably when the device enters power save state the start / stop backlight fades over 3 seconds to dim green . preferably when the device is “ ready for use ”, ie when it enters the setup state , the start / stop backlight fades over 3 seconds to bright green . preferably when in the standby mode , and the ui is left for the idle period , the start / stop backlight remains bright green . preferably when the device enters warming up , or warming ready states , the start / stop backlight remains bright green . preferably when the device enters the cool down state , from run mode the start / stop backlight fades over 3 seconds to bright green . preferably when going to run mode and delivering therapy , or entering the mask fit run state , the start / stop backlight becomes dim blue within 0 . 5 seconds of entering this mode . the blue led remains dim whilst in use unless there is an error , and then it shall be bright blue flashing . by providing the dim blue light for run mode , and turning bright blue flashing only in event of error , the comfort of the patient and any bed partner is enhanced by not having a bright led in the bedroom when trying to sleep . the time periods and transitions described above are by way of example , and may be varied . preferably when the device enters power save state the lcd backlighting fades over 3 seconds from on to off . preferably when the device enters the setup state , adjust state , mask fitting state , or it is awakened from the idle or sleep states by pressing any keys or pressing / turning the push button dial , the lcd backlighting fades over 3 seconds from off to on . preferably when the device enters the warming up , warming ready or error state , the lcd backlight becomes on within 0 . 5 seconds of entering these states . preferably when the device enters the cool down state , from run mode the lcd backlight fades over 3 seconds to on . preferably when in standby mode and the ui is not interacted with for the idle period , the lcd backlight fades over 3 seconds to dim . preferably when in run mode and the ui is not interacted with for the sleep period , the lcd backlight fades over 3 seconds to off . fading of the device between the on , dim or off positions allows the patient &# 39 ; s eyes to adjust to the change in brightness in the middle of the night when the device state is changed , for example if the patient wakes up the device or stops it to go to the toilet . fading to dim during standby mode will help save power , yet still provide some backlight for the patient to read the lcd display . fading to off in the run mode both saves power and minimises brightness in the bedroom , as during the run mode the patient will have no need to read the lcd display . preferably when the device enters the power save state the humidifier indicator backlight fades over 3 seconds to off . preferably when the device enters the setup state the humidifier indicator backlight fades over 3 seconds to bright blue . preferably when the device enters the mask fit standby state , the humidifier indicator backlight remains the same as the state from which mask fit was activated from , and returns back to that state when mask fit is complete . preferably the humidifier indicator backlight becomes bright blue within 0 . 5 seconds of entering the error state with the humidifier set to zero . preferably the humidifier indicator backlight becomes bright orange within 0 . 5 seconds of entering the warming ready , cool down or error state with the humidifier set between 0 . 5 and 6 . preferably when the device enters the warming up state , the humidifier indicator backlight fades over 3 seconds to dim orange . preferably when in the standby or run mode , and the ui is left for the idle or sleep period , the humidifier indicator backlight is turned off . preferably when entering the adjust state or mask fit run state , the humidifier indicator backlight fades over 3 seconds to either : a dim orange if either the humidifier or heated tube are set between 0 . 5 and 6 ; or a dim blue if both the humidifier and heated tube are set to zero . the above - described display and bright , dim and off backlighting states , and the fading between them , are used for similar reasoning as described previously in relation to the start / stop button and display backlighting . fig8 to 10 illustrate a control dial and user interface arrangement according to one embodiment of the invention . fig8 shows a table of symbols which are used in discussion of the operation of the control interface further exemplified in fig9 and 10 . the symbols identify the action required to perform a function within the user interface . symbol 806 refers to the action of pushing the start / stop button 306 . symbols 810 and 808 refer to pushing the setup menu key 310 and info menu key 308 respectively . symbol 802 indicates a waiting time for an action to be processed . symbols 804 , 814 and 824 relate to actions performed using the rotary dial 304 . the actions performed are pushing the dial 804 , turning or rotating the dial 814 and pushing and holding the dial pressed for a period of time , such as 3 seconds 824 . fig9 illustrates a sample user interface for a medical device , such as a cpap respiratory apparatus or a humidifier therefor , along with the user functions associated with each . the interface includes a graphical interface such an lcd or other suitable screen for displaying a control menu , with controls nearby on the device for the user to control operation of the device by selection of menu items . in the example of fig9 , the controls include a start / stop button 304 , an information (“ info ”) button 308 and setup button 310 adjacent the screen 302 , and a rotary control dial 306 . in the illustrated user interface arrangement , the start / stop , information and setup buttons may be simply push buttons , optionally backlit to aid user operation in the dark . the dial may be of the type adapted for continuous rotation , or for shuttling left or right of a central position within a limited range of rotation , and is also adapted to operate as a push button to allow additional user input in that manner . as can be seen in fig8 to 10 , there are three different operations of the rotary dial 306 by which the user may input information : by ( 1 ) pushing the dial ; ( 2 ) turning the dial ; and ( 3 ) pushing and turning the dial for a set period , for example for 3 seconds . as described later with reference to fig1 , combinations of controls may also be used . fig1 shows a schematic sample of a control menu structure and the control operations used to navigate within and between the menus and to select items . as shown in fig1 , a top level menu is shown as shown at the left side of fig8 , with menu items settings , options , reminders and configuration . these menu items are represented graphically along the left hand side of the screen display , with the currently selected menu item highlighted as denoted by the lighter square along the left side of each screen display in fig1 , and the corresponding text shown at the top of the screen display . by way of example , fig1 further shows expansion of the options and date menu items . to navigate up or down within a menu , the user turns the rotary control dial left or right , and to access or select the highlighted menu item the user presses the control dial . navigation back up one menu level may be for example by pressing the setup button 306 , or by pressing both the control dial 306 and the setup button 310 , as shown in fig1 . in accordance with an embodiment of the invention , the user controls incorporate an intuitive control which compensates for user preferences in the direction in which that user rotates the control dial to navigate the menu . in particular , the menu format is arranged so that entry into a menu level is at a known position in the menu list , preferably at one end of the menu — for example at the top menu item settings in the top level menu shown in fig1 , or at the item climate cntrl within the options menu — while the exit from that menu level is at the opposite end of that menu list . the direction that the user initially rotates the control dial 306 to navigate away from that first menu item is detected and that rotary direction is assigned to be the down direction within the menu , so that further rotation of the dial in that direction continues downward navigation within the menu , while rotation in the opposite direction causes upwards navigation through the menu . therefore , in the example of fig1 , if the user initially turns the dial anticlockwise to navigate away from the settings menu item in the top menu level to the sleep quality menu item , then turning the dial anticlockwise is assigned to be the down direction to navigate down the menu items list and turning clockwise to be the up direction to navigate back up the menu items list . in this way , the device controls will adjust automatically to the user preference on the dial operation . the assignment of the up and down directions may be re - assigned each time a new menu level is entered , or may be retained for a longer duration , for example for the duration of the user session . the intuitive dial control may be incorporated by any suitable means , for example within the computer control software of the device . it will be appreciated also that the intuitive dial control in accordance with the exemplary embodiment may have application beyond the medical respiratory devices to which the invention relates primarily , to other devices which employ a rotary control dial . the flow generator preferably incorporates automatic switching between modes of the device , as described below : preferably in patient run mode — when there is no interaction with the ui for a waiting period of 30 seconds , the ui will automatically return to either , the patient climate control , humidifier level , heated tube level or home screen depending what is attached . this allows the patient to adjust their humidity or heated tube setting during the night without looking at the display . in one form “ no interaction ” can include minor interaction . for example , the user interface may return to a patient climate control mode in spite of a short period of interaction that may result from bumping or touching the user interface . whilst a period of 30 seconds is preferred for the required period , in other forms , other waiting periods may be used , such as about 5 seconds , or several minutes . preferably in standby mode — when there is no interaction with the ui for the idle timeout duration , the ui will automatically exit the patient setup menu and go to the patient home screen in the idle state . preferably during run mode in the patient menu , the ui will not allow the user to enter the patient info menu . in one form , when adjusting a numeric parameter , when the dial is turned slowly , it will adjust a parameter in minimal increments , eg 0 . 2 cmh2o per encoder increment , but when the dial is turned quickly , it will adjust the parameter in whole number increments , eg 1 . 0 cm h2o per encoder increment . in a preferred form , the controls of the user interface are located on the flow generator . hence some controls perform dual function of being able to control the humidifier as well as aspects of the flow generator . for example the dial may be able to control ramp time , pressure and humidification ( including climate control level , heated tube temperature and humidity ). in this specification , the word “ comprising ” is to be understood in its “ open ” sense , that is , in the sense of “ including ”, and thus not limited to its “ closed ” sense , that is the sense of “ consisting only of ”. a corresponding meaning is to be attributed to the corresponding words “ comprise , comprised and comprises where they appear . while particular embodiments of this invention have been described , it will be evident to those skilled in the art that the present invention may be embodied in other specific forms without departing from the essential characteristics thereof . the present embodiments and examples are therefore to be considered in all respects as illustrative and not restrictive , the scope of the invention being indicated by the appended claims rather than the foregoing description , and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein . it will further be understood that any reference herein to known prior art does not , unless the contrary indication appears , constitute an admission that such prior art is commonly known by those skilled in the art to which the invention relates .
an apparatus for treating sleep disordered breathing may include : a flow generator to deliver a supply of air at positive pressure to a patient ; a user interface , the user interface comprising : a display configured to display a plurality of screens ; and a set of controls ; and a controller in communication with the user interface and configured to control operation of the flow generator , wherein the flow generator is configured to couple with at least one accessory device and during a first mode of operation of the flow generator the controller determines a first screen of the plurality of screens to display on the display based on the at least one accessory device , the first screen of the plurality of screens being configured to enable adjustment of one or more parameters related to the operation of the at least one accessory device or the flow generator using the set of controls .