fig1 schematically shows a scanner 1 of an inventive magnetic resonance apparatus , which has a communication system with a first communication device 2 , which is implemented in the main magnetic unit 3 , and a second communication device 4 , which is provided at the patient bed 5 . this diagram shows a basic cross - section through the magnetic resonance device 1 , from which the basic field magnet 3 and the patient receptacle 6 are thus easily visible . for simplicity this diagram shows only the components relevant for the present invention ; the other construction of the magnetic resonance device 1 , with gradient coils , radio - frequency coils , basic field magnet , etc . is widely known in the art . integrated into the cladding of the patient receptacle 6 is an illuminating device 7 for the latter , which is designed in this case as a plurality of circumferential illuminating rings 8 with white light emitting leds 9 . illuminating devices 7 in which the led arrays extend longitudinally along the patient receptacle 6 or are otherwise arranged , are of course also possible . the illuminating device 7 illuminates the patient receptacle 6 evenly with white light . this light from the illuminating device 7 is now used as a transmission medium for transmitting a useful signal to the second communication device 4 , for which purpose the first communication device 2 also has a control circuit 10 in addition to the illuminating device 7 as the light source , which control circuit 10 generates a control signal in a manner explained in greater detail with reference to fig2 , so that a transmit signal is communicated by the leds 9 . this is received by a light receiving device of the second communication device 4 and processed further as a receive signal in a control device located therein , in order to extract the useful signal . the useful signal in this case is an acoustic signal , for example comprising voice and / or music , which is emitted to a headset 11 connected to the second communication device . also indicated at the patient bed 5 is a pneumatically operated call ball 12 for the patient ; it should be noted here that embodiments are also possible in which the communication that takes place from the first communication device 2 to the second communication device 4 is not unidirectional , but bidirectional , which is also possible for example using light - differentiated wavelengths , wherein the principles still to be described below for ensuring that the useful signal is transmitted as robustly and with as little distortion as possible can of course also be transferred to bidirectional communication . fig2 now shows the construction of the first communication device 2 in greater detail in a further schematic diagram . the main components of the first communication device 2 are the control circuit 10 and the light source , i . e . the leds 9 of the illuminating device 7 . from a further control circuit of the magnetic resonance device 1 , the control circuit 10 receives a basic pulse signal as indicated by the arrow 13 , which is used in a carrier signal generation unit 14 to generate a carrier signal t which is phase - locked to the basic pulse signal of the magnetic resonance device 1 , at a frequency of 2 . 5 mhz . this means that the frequency of the carrier signal , 2 . 5 mhz , is produced by multiplication with a rational factor from the frequency of the basic pulse signal of the magnetic resonance device 1 and is phase - locked to it . a useful - signal source 15 delivers the useful signal n , which is also usually fed to the control circuit 10 from the exterior , to a phase modulator 16 , which adds the useful signal n to the carrier signal t by analog narrow - band phase modulation . a phase - modulated carrier signal t ′ is produced , which is forwarded to a modulatable power source 17 . to this latter , a brightness value h is supplied by a brightness control unit 18 , the power source 17 generating a control signal s for the leds 9 from the phase - modulated carrier signal t ′ and the brightness value h , which control signal contains a suitable direct component for the required brightness value h , in which the intensity of the leds 9 can then easily be varied with the phase - modulated carrier signal t ′ in a way that is imperceptible for the observer . the leds 9 of the illuminating device 7 then emit light 19 as indicated by the arrows . fig3 shows a corresponding schematic diagram of the second communication device 4 , which — in addition to the light receiving device 20 — likewise , as already mentioned , has a control device 21 which implements the receiving electronics . the light 19 falls through a light inlet aperture onto the light receiving device 20 , which has an optical concentrator 22 , an optical filter 23 for the discrete wavelengths emitted by the leds 9 , and a photodetector 24 . by amplification of the light 19 in the optical concentrator 22 and selection of the light 19 emitted by the leds 9 by means of the optical filter 23 , noise effects are reduced and the signal - to - noise ratio is increased . since the direct component is already removed on the side of the photodetector 24 , finally the phase - modulated carrier signal t ′ is essentially received in turn as the receive signal e and forwarded to the control device 21 . the receive signal e is used there firstly to generate an internal pulse signal i in a pulse signal generation unit 25 , which has a frequency which is produced by multiplication by a rational factor from the frequency of the carrier signal t and is defined out of phase to the carrier signal t . the internal pulse signal i is thus phase - locked to the carrier signal t and thus to the basic pulse signal of the magnetic resonance device 1 . in this way the demodulator 26 , to which the receive signal e is also supplied , functions as a synchronous demodulator . the demodulator 26 again receives the useful signal n , which can be supplied to the headset 11 by a low - frequency interface 27 . further electronic components can also be used to convert signals to intermediate frequencies at which they can be further processed ; furthermore , amplifiers etc . are of course usually provided , in particular on the side of the control device 21 , but these are omitted here for the sake of clarity . other electronic components can of course also be added as components of the receiving electronics or control circuit 21 of the second communication device or of the control circuit 10 of the first communication device 2 , which for example ensure improvements to the signal quality , and so forth . after the useful signal n has been transmitted in analog form , it can be directly used as an acoustic signal in the headset 14 . the second communication device 4 , which can also be integrated in the headset 11 , evidently does not have a radio - frequency interface . its receiving electronics ( control device 21 ) are shielded from the exterior together with the light receiving device 20 by a radio - frequency shield 28 . although modifications and changes may be suggested by those skilled in the art , it is the intention of the inventor to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of his contribution to the art .
in a method for communicating between a first communication device of a magnetic resonance apparatus and a second communication device , in particular one that is mobile and on the patient side , of the magnetic resonance apparatus , a communication technology using visible light is used as the transmission medium for transmission of a useful signal from at least one of the communication devices to the other communication device , in particular from the first communication device to the second communication device .