Abstract:
The present invention relates to a respiratory apparatus, in particular a CPAP-apparatus. The apparatus comprises an illumination device for illuminating a display or operating members, and a controller connected with the illumination device for switching the illumination on and off. The apparatus moreover comprises a sensor likewise connected with the controller and outputting a signal to the controller which causes the controller to switch on the illumination.

Description:
CROSS REFERENCE TO RELATED CO-PENDING APPLICATIONS  
       [0001]     This application is a continuation of international application number PCT/DE03/003593 (publication number: WO 2004/045692 A1) filed on Oct. 29, 2003 and entitled VENTILATOR, IN PARTICULAR CPAP DEVICE COMPRISING AN ILLUMINATION DEVICE and claims the benefit of the above-mentioned international application and the corresponding German national patent application number 102 53 934.0-09 filed on Nov. 19, 2002 and entitled BEATMUNGSGERÄT, INSBESONDERE CPAP-GERÄT MIT EINER BELEUCHTUNGSEINRICHTUNG the contents of which are expressly incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The invention relates to a respiratory apparatus according to the preamble of claim  1 , in particular to a CPAP-apparatus and a controller for switching an illumination device on and off.  
       BACKGROUND OF THE INVENTION  
       [0003]     “Clapping switches” are known from the prior art, which react on acoustic pulses such as clapping. They can comprise, for example, a plug for the mains supply and a corresponding socket. The clapping switch is supplied with electrical power via the plug and the mains supply. Upon initial clapping it connects its socket to the mains supply, after clapping a second time it disconnects the socket from the mains supply. If the plug of a lamp is plugged into the socket of the clapping switch light can be switched on and off by clapping.  
         [0004]     Additionally known are lamps with movement detectors and light sensors. Such lamps are used, for example, to illuminate front door areas only when necessary. If the light sensor senses that it gets dark, the light is switched on if the movement detector also detects the movement of a person. A person not knowing the surroundings thus need not look for a possibly non-illuminated switch in the darkness.  
         [0005]     Also the display of mobile telephones, e.g. the S35 of Siemens, is equipped with a display illumination and an illumination of the key legend. Upon pressing any key, the display and key illumination is switched on. If no key is pressed for 10 to 15 seconds, the display and key illumination is switched off again.  
         [0006]     Known are moreover respiratory apparatus or respirators for the mechanical, artificial respiration for all forms of an oxygen deficiency state. They are, inter alia, applied for the long-time respiration. (Roche Medical Dictionary, 4 th  Edition, published by Hoffmann-La Roche AG and Urban &amp; Fischer, Munich, Stuttgart, Jena, Lübeck, Ulm).  
         [0007]     Known are in particular apparatus for performing the CPAP therapy (continuous positive airway pressure). The CPAP therapy is described in Chest. Volume No. 110, pages 1077-1088, October 1996 and in Sleep, Volume No. 19, pages 184-188. A CPAP-apparatus applies, by means of a compressor and via a hose and a nose mask, a positive overpressure up to approximately 30 mbar to the respiratory tract of the patient. This positive pressure is to ensure that the upper respiratory tract remains fully opened during the whole night, so that no obstructive apneas will occur (DE 198 49 571 A1).  
         [0008]      FIG. 1  shows a CPAP-apparatus  1  and a patient  19 . The CPAP-apparatus comprises a housing  4 , a respiratory hose  9  and a respiratory mask  18 . For the generation of a positive pressure the housing  4  includes a turbine  8 . The turbine is also designated as blower, blower unit, compressor, ventilator or fan. In this patent these terms are used synonymously. Furthermore, a pressure sensor  11  and optionally a flow sensor  16  are accommodated in the housing. In the mask, or in the proximity of the mask, one or several small holes  2  are provided which allow the formation of an air flow from the compressor to the holes  2  on the time average. This prevents the accumulation of CO 2  in the respiratory hose  9  and allows the supply of the patient with oxygen.  
         [0009]     The speed of the turbine  8  is controlled by a microcontroller  5  such that the actual pressure measured with the pressure sensor  11  corresponds to a predetermined target pressure. The target pressure is typically preadjusted under the supervision of a medical practitioner and is called titration pressure. The flow sensor can, for example, be a sensor comprising a heating filament  17 .  
       SUMMARY OF THE INVENTION  
       [0010]     According to an embodiment of the invention a respiratory apparatus is provided which comprises an illumination device, a controller and a sensor. The controller is connected with the illumination device for switching the illumination on and off. A sensor is connected to the controller and outputs a signal to the controller which causes the controller to switch on the illumination.  
         [0011]     According to another embodiment of the invention a method for a respiratory apparatus is provided. The method comprises outputting a sensor signal from a sensor of the respiratory apparatus to a controller of the respiratory apparatus which causes the controller to switch on the illumination. Further, a light source is illuminated in response to the sensor signal.  
         [0012]     It is an advantage of the use of a microphone for switching the illumination on that the patient need not even move in order to operate the respiratory apparatus.  
         [0013]     With respect to switching the illumination on at loud ambient noise and with respect to switching the illumination off in a noiseless environment it is an advantage that this criterion frequently automatically switches the illumination on and off correctly. When the patient sleeps it is usually noiseless in the sleeping room. When the patient wakes up he or she makes noise by rustling with the blanket. At this time it is sensible that the illumination be switched on.  
         [0014]     By the detection of amplitude variations in the ambient noise it can be detected whether someone speaks in the ambience of the respiratory apparatus. Thus, the patient may talk to the apparatus in the dark so as to switch on the illumination thereof.  
         [0015]     It is advantageous with respect to an accelerometer that it senses the slight concussions caused, for example, by patient&#39;s groping for the respiratory apparatus.  
         [0016]     An infrared sensor, such as a photodiode or a pyrosensor, is an inexpensive movement sensor which also works in the dark.  
         [0017]     An advantage of a housing window pressing on an infrared sensor resides in that, when correctly selecting the infrared sensor, also movements of the housing and, thus, of the housing window result in a sensor signal. By this the infrared sensor not only detects movements of a hand in front of the respiratory apparatus, but also slight concussions of the apparatus caused by groping movements.  
         [0018]     An advantage of a lens or lens system in front of the infrared sensor resides in that the solid angle may be defined more exactly due to the reaction of the infrared sensor on movements.  
         [0019]     Also a contact sensor advantageously switches the illumination of the respiratory apparatus on when the patient gropes for the respiratory apparatus. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]     Preferred embodiments of the invention will hereinafter be explained in more detail with reference to the enclosed drawings, wherein like numerals represent like parts.  
         [0021]      FIG. 1  shows a CPAP-apparatus according to the invention,  
         [0022]      FIG. 2  shows a circuit for a contact sensor,  
         [0023]      FIG. 3  shows a thermopile for the infrared detection with a corresponding circuitry, and  
         [0024]      FIG. 4  shows the inventive installation of the infrared sensor. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0025]     The CPAP-apparatus according to the invention shown in  FIG. 1  moreover comprises a display  23 , preferably an LCD (liquid crystal display) and/or at least partially transparent operating members  24 . The display and the operating members can be illuminated by an illumination device or light source which may be one or more light emitting diode(s)  15  or one or more light bulb(s)  13 . For a stable operation of light emitting diodes a current limiter, e.g. in the form of a resistor  14 , is necessary.  
         [0026]     Moreover, the CPAP-apparatus according to the invention comprises at least one sensor, which may be a microphone  20 , an accelerometer  21 , an infrared sensor  6 ,  40  or a contact sensor  30 . The sensor signal(s) is/are supplied to the microcontroller  5 . For evaluating the sensor signal from the pressure sensor  11  or the flow sensor  16  the microcontroller  5  preferably comprises one or more analog-to-digital converter(s). Commercially available microcontrollers often include an analog-to-digital converter together with a preceding multiplexer so that, for example, one out of eight analog inputs is connected to the analog-to-digital converter.  
         [0027]     In a simple embodiment the signal supplied by the microphone may be evaluated merely with respect to its amplitude. If the microphone signal, which is rectified and lowpass-filtered with a time constant of 0.3 to 3 s, exceeds a threshold the microcontroller switches on the illumination. The possibly required amplification of the microphone signal, the rectification of the microphone signal and the lowpass-filtering may be performed in an analog circuit or even digitally in the microcontroller  5 .  
         [0028]     In a slightly more complex embodiment amplitude variations of the microphone signal may be evaluated. To this end the microphone signal is likewise rectified and thereafter lowpass-filtered with a time constant of approximately 0.1 s. This amplitude signal can, again, be lowpass-filtered with a longer time constant of, for example, 10 s, so as to obtain a mean amplitude signal. On the other hand, the constant component can be filtered out of the amplitude signal, for example, by means of a capacitor, and the alternating component of the amplitude signal can be rectified and again lowpass-filtered, for example, with a time constant of 1 s, so as to obtain an amplitude variation signal. If the amplitude variation signal divided by the mean amplitude value exceeds a threshold the microcontroller  5  switches on the illumination.  
         [0029]     If the respiratory apparatus is equipped with an efficient microcontroller, the microcontroller may perform a speech recognition so that the respiratory apparatus is entirely controllable by speech. The speech recognition needs not to be very sophisticated since it only has to understand a few commands like pressure on, pressure off, illumination on, possibly increase pressure, decrease pressure etc.  
         [0030]     An accelerometer  21  may serve to detect the slight concussions caused by the patient groping for the CPAP-apparatus and thereby slightly hitting on the CPAP-apparatus. For allowing the optimum detection of such slight impacts the accelerometer  21  is advantageously disposed away from the footprint or foot nipples of the CPAP-apparatus. If the CPAP-apparatus stands on a shelf which is not too stable, the accelerometer  21  can also detect slight concussions of the shelf bottom caused by the groping and subsequently switch on the illumination.  
         [0031]     For detecting movements in the proximity of the CPAP-apparatus, e.g. the gripping or groping of the patient for the CPAP-apparatus, an infrared sensor may be applied as an inexpensive solution. This infrared sensor may either be a photodiode  6  or an infrared sensor with a thermopile  40 . The photodiode  6  is biased in the non-conducting direction. The more light falls onto the photodiode, the higher is the current through the photodiode. This current is converted into a voltage, for example, at the resistor  7 . As the photodiode is to detect movements, the alternating component of the voltage dropping at resistor  7  is advantageously decoupled from the voltage by capacitor  10 . The alternating signal supplied by capacitor  10  is furnished to component  12 . Component  12  may be a band-limiting amplifier or a rectifying amplifier with subsequent lowpass as to disburden the microcontroller  5 . In another embodiment component  12  may be a comparator which already supplies a digital output signal to the microcontroller  5 , in particular to an interrupt input of the microcontroller  5 .  
         [0032]     One possible circuitry of a contact sensor is shown in  FIG. 2 . The resistor  31  applies a voltage U s  to the electrode  32  wherein, in the embodiment described first, the voltage U s  is to be a direct voltage. The capacitor  34  decouples the alternating component of the voltage applied to electrode  32  and furnishes said alternating component to component  35 . Component  35  in its simplest form may be a comparator which outputs, for example, a logic zero corresponding to 0 V if a voltage underneath a threshold is applied to its input, and otherwise outputs a logic one corresponding, for example, to 5 V. If an operator now contacts the electrodes  32  and  33  simultaneously, the operator constitutes an electric resistance between said two electrodes due to which the voltage at electrode  32  drops. By this a negative voltage pulse is formed by capacitor  34 , which may be detected in component  35  and converted into a digital negative pulse. In particular if U s  is a direct voltage the capacitor  34  may be omitted.  
         [0033]     In another embodiment the voltage U s  may be an alternating voltage. In the case of alternating current, too, the amplitude of the alternating voltage at electrode  32  drops if the electrodes  32  and  33  are contacted simultaneously. This can, for example, be detected by a simple comparator, which outputs a square wave alternating voltage signal if the electrodes  32  and  33  are not contacted, and which outputs a direct voltage signal if the electrodes  32  and  33  are contacted. In another embodiment the alternating voltage supplied by the capacitor  34  may at first be rectified, and the amplitude of the rectified alternating voltage may be compared with a threshold in component  35 . The contact  36  symbolizes the connection to the microcontroller  5 .  
         [0034]     In the case of alternating voltage the electrode  33  may be omitted. If a patient contacts the electrode  32  his body acts as a large capacitor against ground as a result of which also the amplitude of the alternating voltage at electrode  32  drops. In this embodiment the electrode  32  may reticulate over the housing of the respiratory apparatus so that the contact sensor  30  detects each movement of the housing. In another embodiment the housing may also be made of a conductive synthetic material which then forms the electrode  32 . The conductivity of the synthetic material need not be high as the resistance of the patient&#39;s skin also is in the 100 kOhm range.  
         [0035]     Infrared sensors, in particular for distant infrared, frequently comprise thermopiles. Said thermopiles measure the temperature difference between a hotter spot  41  and a colder spot  42 . The hotter spot  41  is blackened such that it absorbs light in a frequency range as broad as possible, i.e. it appears as black. The thermopile consists of a meander-shaped arrangement of two different conductors which in particular have a different position in the thermoelectric contact series. The thermopile supplies a voltage being proportional by approximation to the incident luminous power. As movements are to be detected, the alternating component of the voltage is preferably decoupled by capacitor  45 , amplified by amplifier  46  and furnished to the microcontroller  5  via the terminal  47 .  
         [0036]     The amplifier  46  may also be replaced by component  12 .  
         [0037]     It has moreover been found that an infrared sensor also outputs a sensor signal in response to slight concussions of the housing, provided that it is installed according to  FIG. 4 .  FIG. 4  shows an infrared sensor  51 , a Plexiglas window  52 , housing parts  53 , a sensor socket  54 , connecting leads  55 , a printed circuit board  56  and electrical and electronic components  57 . It is essential that the sensor is pressed by its connecting leads with its window against the Plexiglas window  52 . To this end it is not necessary that the connecting leads be bent as is shown in  FIG. 4 . However, in order to also guarantee a reproducible mechanical contact between the infrared sensor  51  and the Plexiglas window  52  during the production, it is advantageous if the connecting leads are bent so as to act as springs.  
         [0038]     In the foregoing, the invention was explained in more detail by means of preferred embodiments. It is, however, obvious for a person skilled in the art that various alterations and modifications may be made without departing from the spirit of the invention. Therefore, the scope of protection is defined by the following claims and their equivalents.  
       LIST REFERENCE NUMERALS  
       [0000]    
       
           1  CPAP-apparatus  
           2  hole  
           4  housing  
           5  microcontroller  
           6  photodiode  
           7  resistor  
           8  turbine  
           9  respiratory hose  
           10  capacitor  
           11  pressure sensor  
           12  component  
           13  filament bulb  
           14  resistor  
           15  light emitting diode  
           16  flow sensor  
           17  heating filament  
           18  respiratory mask  
           19  sleeping person  
           20  microphone  
           21  accelerometer  
           22  lens  
           23  LCD  
           24  operating member  
           30  contact sensor  
           31  resistor  
           32 ,  33  electrode  
           34  capacitor  
           35  component  
           36  connecting line  
           40  thermopile  
           41  hot end  
           42  cold end  
           43  first conductor  
           44  second conductor  
           45  capacitor  
           46  amplifier  
           47  connecting line  
           51  infrared sensor  
           52  plexiglas window  
           53  part of the housing  
           54  sensor socket  
           55  connecting leads  
           56  printed circuit board  
           57  electric and electronic components