Abstract:
An electric-motor furniture drive includes a power supply device, a manual control for moving movable furniture components relative to each other, and an electric motor with reversible rotation direction. A speed-reducing transmission is connected downstream of the electric motor and an additional transmission is connected downstream of the speed-reducing transmission. The power supply device has a mains connection, transforms the mains-side input voltage into at least one output-side low voltage and is configured for galvanic isolation between the mains-connected input side and the output side for operating the electric-motor furniture drive. The power supply device is designed as a switched-mode power supply and has an intermediate circuit, a control device for controlling the switched-mode power supply, and a secondary unit. The power supply device provides an output-side operating voltage at the output thereof in an operating state and provides an output-side idle voltage at the output in an idle state.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
     This application is the U.S. National Stage of International Application No. PCT/EP2012/052106, filed Feb. 8, 2012, which designated the United States and has been published as International Publication No. WO 2012/107474 and which claims the priority of German Patent Application, Serial No. 10 2011 000 602.8, filed Feb. 9, 2011, pursuant to 35 U.S.C. 119(a)-(d). 
     BACKGROUND OF THE INVENTION 
     The invention relates to an electric-motor furniture drive having a power supply device for adjusting movable furniture components relative to one another. 
     Such electric-motor furniture drives are known in various embodiments. They are implemented as linear drives having a linearly adjustable output element or as rotational drives having a rotating output element and have proven themselves extremely well in practice. The linear drives have one or a number of electric motors, wherein a speed reduction gear is connected downstream from each motor and a further gear, for example, in the form of a threaded spindle gear, is connected downstream from the speed reduction gear, which further gear generates a linear movement of the output element from the rotational movement of the motor. The rotational drives have at least one speed reduction gear connected downstream from the respective electric motor, wherein the last gearing element forms the output gear. The output element of the respective electric-motor furniture drive is connected to a fixed furniture component and/or to a movable furniture component, so that the movable furniture components are adjusted relative to one another in the event of operation of the electric motor. The furniture can be implemented as a slatted frame, worktable, bed, recombinant surface, treatment couch, hospital or healthcare bed, and also a lifting device for persons such as lifters or patient lifters. 
     Switched power supplies have proven themselves best as the power supply devices for operating the electric-motor furniture drives. The power supply device has an operating state “off” in the event of disconnection from the network and an operating state “operation” in regular operation. The switched power supplies have a isolation transformer switched at high frequency by a control module, which can also be designated as a transformer or as a high-frequency transformer, which is turned on and off by an upstream semiconductor switch on the primary side at a high switching frequency. For this purpose, a separate intermediate circuit is assigned to the control module, which has a power source of the control module and supplies the control module with electrical power. 
     Document DE 10 2006 049 715 A1 illustrates a power supply for motorized drives, which is implemented in a plug housing as a switched power supply. 
     The prior art of a network circuit breaker or a higher-order network circuit breaker will also be discussed. The network circuit breaker, e.g., of an apartment, is introduced between the apartment installation and the public power supply network and detects whether an electrical consumer, e.g., a light, is switched on or off. The apartment installation means the electrical wiring of the apartment for the network voltage. When an electrical consumer is no longer still turned on, the network circuit breaker disconnects the apartment installation from the public power supply network. The network circuit breaker then generates a test voltage, e.g., a harmless DC voltage of a specific level, and switches it to the apartment installation. If a consumer is now switches on, it recognizes the test voltage and causes the network circuit breaker to connect the apartment installation to the public power supply network again. Such a network circuit breaker can also be used regionally or respectively for a room. 
     SUMMARY OF THE INVENTION 
     The invention is based on the object of providing an improved electric-motor furniture drive having a power supply device of the type described in greater detail hereafter. 
     The object is achieved with an electric-motor furniture drive having a power supply device and having a manual control for adjusting movable furniture components relative to one another, wherein the electric-motor furniture drive has at least one electric motor, which is reversible in the rotational direction, wherein a speed reduction gear is connected downstream from each electric motor and wherein a further gear is connected downstream from each speed reduction gear, and wherein the power supply device has a network terminal, which is implemented as connectable to the network, wherein the power supply device transforms the network-side input voltage into at least one output-side low voltage, and has an isolation transformer or a transformer unit for the electrical disconnection between the network-connected input side and the low-voltage-providing output side for operating the electric-motor furniture drive, wherein the power supply device is implemented like a switched power supply and has an intermediate circuit, a control unit for controlling the switched power supply, and a secondary unit, wherein the power supply device has an operating state in regular operation of the electric-motor furniture drive and an idle state when the electric-motor furniture drive is not actuated, wherein the power supply device provides at its output an output-side operating voltage in its operating state and provides at its output an output-side idle voltage, instead of the operating voltage, in its idle state. 
     The power supply device can provide at its output an output-side operating voltage in its operating state and, instead of the operating voltage, an output-side idle voltage in its idle state. In the idle state, a harmless and particularly power-saving small safety voltage can thus be available as a test voltage for the electric-motor furniture drive with the idle voltage. Additional auxiliary voltage sources in the form of batteries or capacitors are not necessary. 
     Accordingly, an electric-motor furniture drive having a power supply device and having a manual control for adjusting movable furniture components relative to one another is provided, wherein the electric-motor furniture device has at least one electric motor, which is reversible in its rotational direction, wherein a speed reducing gear is connected downstream from each electric motor, and wherein a further gear is connected downstream from each speed reducing gear, and wherein the power supply device has a network terminal, which is implemented as connectable to the network, wherein the power supply device transforms the network-side input voltage into at least one output-side low voltage, and has an isolation transformer or a transformer unit for the electrical disconnection between the network-connected input side and the low-voltage-providing output side for operating the electric-motor furniture drive, wherein the power supply device is implemented like a switched power supply and has an intermediate circuit, a control unit for controlling the switched power supply, and a secondary unit, wherein the power supply device has an operating state in regular operation of the electric-motor furniture drive and an idle state if the electric-motor furniture drive is not actuated. The power supply device provides at its output an output-side operating voltage in its operating state and an output-side idle voltage, instead of the operating voltage, in its idle state. 
     Therefore, the electric-motor furniture drive having this power supply device can also have an extremely low power consumption in standby operation, in which it is connected to an electrical supply network and is ready for actuation. The requirement for low power consumption of devices can thus also be met in standby operation. 
     In one embodiment, the power supply device may also have a load recognition unit having a sensor, and a control block, wherein the control block is connected to a reference voltage unit of the secondary unit and is implemented to switch over the output-side operating voltage into the output-side idle voltage. Simple and reliable recognition of load states can thus be provided, which can unambiguously detect the operating state and the idle state. The reference voltage unit of the secondary unit can be used to generate the different voltages. Only a few additional components are necessary. 
     In one alternative embodiment, the power supply device can also have a load recognition unit having a sensor, and a control block, wherein the control block is connected to a switchover unit of the secondary unit for switching over the output-side operating voltage into the output-side idle voltage. A simple switchover can thus be possible if two voltages are already present or are being generated. 
     The switchover unit can have a switching element which, in the deenergized state, switches the idle voltage to the output of the power supply device on the output side. The switching element can be a relay and/or a semiconductor switch, for example. 
     The load recognition unit can have a comparator. Depending on the scope of such a comparator, not only the operating state and the idle state can be unambiguously detected and set, but rather also intermediate states can be recognizable. 
     The comparator can be connected to a reference unit, whereby states can be detectable in a better way. 
     Still better detectability and differentiation can be achieved if the reference unit comprises a constant current source. This constant current source of the reference unit can have two parallel current paths having a pair of pnp-transistors and a pair of npn-transistors for this purpose. Therefore, particularly low currents, e.g., in the microampere range, can be controllable and can also provide satisfactory results in the case of low idle voltages. Such a constant current source can also be constructed discretely using simple components in a cost-effective manner. A further advantage can be that also in the case of test voltages of network circuit breakers having low idle voltages resulting therefrom in the idle state of the power supply device, an unambiguous load recognition can be possible and a functionality of the network circuit breaker can be maintained. 
     In a further embodiment, a voltage regulator can be provided for generating the idle voltage and can be connected to the operating voltage as the input voltage. This voltage regulator can be a commercially available and therefore cost-effective component. 
     In an alternative embodiment, the idle voltage can be continuously connected to the output of the power supply device, wherein in the operating state the operating voltage can be activated. Components can thus be saved, for example, only one closing contact and no switchover contacts are necessary. 
     In a further embodiment, the power supply device can have a display unit for displaying the operating voltage and the idle voltage. Two-color LEDs can be used for this purpose, in order to save installation space and obtain unambiguous displays. In a preferred embodiment, the first LED is implemented as a permanently green illuminating LED and the second LED is implemented as a red illuminating LED which can be switched on, wherein in a further embodiment a series resistor is connected to at least one LED. During operation of both LEDs, the two-color LED emits a mixed light, which can be formed by a yellow color and which is implemented as variable by adapting the at least one series resistor. 
     In still a further embodiment, the power supply device can be provided with a switchable and/or variable initial load, which is implemented and is temporarily connectable to the terminals of a network cable in such a manner that an unambiguous recognition of the operating state of the power supply device is formed for a network circuit breaker. The field of use can thus be expanded using network circuit breakers of different constructions. 
     The motor controller and/or the manual control can be provided with an auxiliary power source, whereby emergency lowering can also be possible. 
     The auxiliary power source can be a battery, an accumulator, and/or a capacitor. 
     If the idle voltage is, for example, 3 V or 5 V, it can therefore be possible that it can be sufficient to maintain further safe operation of, for example, functional elements such as processors of the motor controller and error messages or signal receivers such as radio receivers or infrared receivers or a display device or a bus device. 
     The operating voltage has a substantially higher potential and is typically approximately 30 V, in other embodiments in the range from 24 V to 40 V. The special advantage in switching over and/or providing the idle voltage at the output of the power supply device is that, for the power supply of the functional elements described at the beginning, this idle voltage can be used, so that separate power supply circuits of the functional elements can be omitted, and thus the installation expenditure for the electric-motor furniture drive and its individual components is substantially reduced. In addition, electric-motor furniture drives of the prior art have a substantially higher standby consumption according to their nature, since they have high-loss voltage regulator or current divider circuits, in order to adapt the functional elements described at the beginning, which cannot be operated using the high operating voltage, to the operating voltage. 
     A further embodiment provides a power supply device having two output-side voltages, wherein at least one voltage, for example, in the form of the idle voltage, is permanently applied and the other voltage, for example, in the form of the operating voltage, is implemented as activatable. Therefore, the output of the power supply device has, in a first and simplified embodiment, two terminals, to which the idle voltage and the activatable operating voltage are applied. A further embodiment of the power supply device has an output in the form of three terminals, wherein the idle voltage is applied via two terminals and the third terminal has the potential of the operating voltage in relation to one of the other terminals. A further and supplementary embodiment of the power supply device has an output in the form of four terminals, wherein the idle voltage is applied via two terminals and the operating voltage is applied via two further terminals. The output of the power supply device can therefore be implemented as a two-pole, a three-pole, or a four-pole terminal. 
     The supply cable can consist of two supply lines or wires in a so-called two-wire embodiment. In a so-called three-wire embodiment, there are three lines, and in a so-called four-wire embodiment, the supply cable has four lines. 
     In the case of the two-wire embodiment, the two lines of the supply cable are implemented as the positive and negative lines for both the operating voltage and also the idle voltage. 
     In the case of the three-wire embodiment, in addition to the positive and negative lines, a control line is provided, which conducts a control signal generated by the manual switch upon actuation thereof and causes a switchover of the power supply device from the operating voltage to the idle voltage and vice versa. One of the two lines which are provided as the positive and negative lines is a shared line (e.g., ground line for the control signal). 
     In the case of the four-wire embodiment, the fourth line is the ground line for the control signal, wherein control lines and positive and negative lines are embodied separately and do not use a shared line. 
     Further characteristics and features result from the following description of a preferred exemplary embodiment and are the subject matter of further subclaims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The invention will be explained in greater detail on the basis of the appended drawings. In the figures: 
         FIG. 1  shows an exemplary and schematic view of a furniture drive according to the invention, which is implemented as a linear drive, having a power supply device; 
         FIG. 2  shows a schematic block diagram of an exemplary embodiment of the power supply device according to  FIG. 1 ; 
         FIG. 3  shows a schematic block diagram of a first exemplary embodiment of a load recognition unit of the power supply device according to  FIG. 2 ; 
         FIG. 4  shows a schematic block diagram of a second exemplary embodiment of a load recognition unit of the power supply device according to  FIG. 2 ; 
         FIG. 5  shows a schematic circuit diagram of a reference unit of the load recognition unit according to  FIG. 4 ; 
         FIG. 6  shows a schematic block diagram of an exemplary embodiment of a switchover unit of the power supply device according to  FIG. 2 ; and 
         FIG. 7  shows a schematic block diagram of an exemplary embodiment of generation of an idle voltage of the power supply device according to  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  shows an electric-motor furniture drive  1  having a power supply device  5 .   
     The electric-motor furniture drive  1  is in this exemplary embodiment a so-called linear drive  2 , and the power supply device  5  is implemented as a switched power supply. The linear drive  2  has a lifting pipe  3 , which is extendable and retractable depending on the rotational direction of an electric motor (not shown in greater detail), on whose free end a connecting part in the form of a clevis  4  is attached. A further connecting part in the form of a further clevis  4  is fastened on the housing of the linear drive  2 . The respective connecting part is connected in a way not shown in greater detail to a furniture component in each case, so that during operation of the electric motor, the furniture parts connected to the linear drive  2  move relative to one another. 
     According to the illustration in  FIG. 1 , the power supply device  5  is connected via a network cable  110  to a network plug  8 , wherein in another embodiment (not shown in greater detail), the network plug  8  can be arranged on the power supply device  5 . It is also to be noted that the power supply device  5  according to the illustration in  FIG. 1  is provided with an enclosing housing, so that the network plug  8  can be placed or formed on the housing. 
     An output of the power supply device  5  is connected via a supply cable  111  to a motor controller  6 , to which the linear drive  2  (also representative for more than one linear drive  2 ) is connected using a motor cable  112 . 
     Furthermore, the power supply device  5  is additionally connected by a control line  113 . 2  to the motor controller  6  in one variant, a so-called three-wire embodiment. This variant will be explained in greater detail hereafter. 
     A manual control  7  is connected in wired form to an operating cable  113  at the motor controller  6 , wherein according to the illustration in  FIG. 1 , the manual control  7  has two pushbuttons. According to another embodiment (not shown in greater detail), the manual control  7  is coupled via a wireless transmission link to the motor controller  6  and transmits radio waves or infrared light waves, for controlling the at least one electric motor, i.e., the linear drive  2 , to the motor controller  6 . 
     According to the illustration in  FIG. 1 , in a first embodiment, the manual control  7  is connected to a motor controller  13 , wherein the motor controller  6  is implemented as a relay controller having relay switches and/or as a semiconductor circuit having semiconductor switches. The manually operable button switch of the manual control  7  switches the control current of the relay switches or the semiconductor switches, wherein the power switches of the relay switches or the semiconductor switches switch the high motor current of the linear drive  2 . 
     According to the illustration in  FIG. 1 , in a second embodiment, the manual control  7  is connected to the motor controller  6 , which connects the supply cable  111  of the power supply device  5  and a motor cable  112  of the electric motor of the linear drive  2  and the electric lines of the manually operable button switch of the manual control  7  to one another. According to this embodiment, the contacts of the manually operable button switch of the manual control  7  are implemented as power switches and switch the high motor current of the electric motor of the linear drive  2  in the event of a button press. 
     In a refining embodiment (not shown in greater detail), the power supply device  5  is inserted into the housing of the linear drive  2  or is attached thereon, wherein the linear drive  2  can be constructed like a double drive (not shown in greater detail), which receives at least one motor, but preferably two motors in a shared housing. 
     The network plug  8  supplies, via the network cable  110 , the input-side network voltage to the power supply device  5  implemented as a switched power supply, which outputs a low voltage in the form of a DC voltage as operating voltage U 1  on the secondary side and relays it to a motor controller  6 . The operating voltage U 1  is at the level of approximately 29 V, for example, and is used in an operating state of the power supply device  5  for operating the motor controller  6  and the linear drive  2 . 
     In addition, the power supply device  5  outputs a further voltage on the secondary side, which is designated as the idle voltage U 2 , e.g., is approximately 5 V DC voltage, and is supplied in an idle state, which differs from the operating state, of the power supply device  5  to the motor controller  6  instead of the operating voltage U 1 . The function of the idle voltage U 2  is, in the idle state, to detect an actuation of the manual control  7  and to signal this to the power supply device  5 . The power supply device  5  then again provides the operating voltage U 1  at its full level and performance capability to the motor controller  6  and the linear drive  2  for operation in the operating state. In another embodiment, the idle voltage U 2  has a further function, in that it is used as the supply voltage of functional elements (not shown in greater detail) or forms the voltage source of functional elements (not shown in greater detail). 
       FIG. 2  shows a schematic block diagram of an exemplary embodiment of the power supply device  5  according to  FIG. 1 . 
     Power lines or paths are indicated by thick lines and control lines or paths are indicated by thin lines. 
     The power supply device  5  has an input circuit  10 , an intermediate circuit  11 , a transformer unit  12 , a secondary unit  13 , a coupling device  14 , a control unit  15 , and a load recognition unit  17  having a control block  19 . A signal processing unit  18  can also be connected between load recognition unit  17  and control block  19 . 
     The input circuit  10  can be coupled on the input side (indicated by arrows) to a power supply network  100  via network plug  8  and network cable  110 . For the connection to the power supply network  100 , for example, a network circuit breaker  9  can be installed as a so-called higher order network circuit breaker in a household installation. The free arrows indicate connection possibilities for further consumers. 
     The network circuit breaker  9  releases a household installation network as soon as no electrical consumer is still connected. The network circuit breaker  9 —depending on the embodiment—then applies a test voltage to the household installation network, in order to detect when a consumer is switched on. If this is the case, the network circuit breaker  9  connects the household installation network to the power supply network  100  again. 
     Typical network suppression elements, such as capacitors and throttles, and also fuses (not shown in greater detail here) are contained in the input circuit  10  of the power supply device  5 . The input circuit  10  is connected to the intermediate circuit  11 , which has a rectifier and a switching module, e.g., a switching transistor. The intermediate circuit  11  is coupled to the switching module at the transformer unit  12 . The transformer unit  12  has a transformer having electrical disconnection  16 , which extends through the power supply device  5 . On the secondary side of the transformer unit  12 , the secondary unit  13  is connected, which provides the operating voltage U 1  to supply the linear drive  2  via the supply cable  17 . 2  to the motor controller  6  ( FIG. 1 ). A feedback of the secondary unit  13  is arranged via the decoupling unit  14 , e.g., an optocoupler  16  having electrical disconnection  16 , at the control unit  15 . The control unit  15  controls the switching module of the intermediate circuit  11  to regulate the operating voltage U 1  and in a specific case, as explained in greater detail hereafter, also the idle voltage U 2  of the secondary unit  13 . For this purpose, the secondary unit  13  has a reference voltage unit (not shown). 
     Furthermore, the control line  113 . 2  (see  FIG. 1 ) is shown, which is connected here between the motor controller  6  and the secondary unit  13 . 
     In addition, the power supply device  5  in this exemplary embodiment has a display unit  20  which displays, for example, whether the operating voltage U 1  or the idle voltage U 2  is applied to the motor controller  6 . This will be explained in greater detail hereafter. 
     The load recognition unit  17  is used to recognize whether the electric motor of the linear drive  2  (or also another additional load, for example, a reading lamp) is turned on as actuated by the manual control  7  and consumes current or is turned off. Furthermore, the load recognition unit  17  can detect whether the manual control  7  is still actuated when the linear drive  2  is switched off by an end switch, for example. The load recognition unit  17  can also recognize when the manual control  7  is actuated in the idle state of the power supply device  5 . 
     A further function of the load recognition unit  17  comprises switching the power supply device  5  from its operating state into its idle state if a consumer is no longer turned on, and switching the power supply device  5  from its idle state into its operating state when a consumer is to be switched on. 
     For this purpose, the load recognition unit  17  outputs signals based on its detected values, which are conditioned and/or processed appropriately in the signal processing unit  18  in such a manner that they can be used for further processing in the control block  19 . This can consist of, for example, the signals generated by the load recognition unit  17  being lengthened or shortened with respect to time or only being relayed after a specific delay time. 
     The control block  19  is connected to the secondary unit  13  and controls it based on the signals of the load recognition unit  17  in such a manner that the power supply device  5  delivers the operating voltage U 1  in the operating state and the idle voltage U 2  in the idle state. This will be described in greater detail hereafter. 
       FIG. 3  shows a schematic block diagram of a first exemplary embodiment of the load recognition unit  17  of the power supply device according to  FIG. 2 . 
     The load recognition unit  17  in this exemplary embodiment comprises a sensor  21  having an input terminal  17 . 1  and an output terminal  17 . 2  and also a comparator  22  having an output terminal  17 . 3  (see also  FIG. 2 ). The comparator  22  is connected to an input on the sensor. 
     The sensor  21  is connected in series to the motor controller  6  and therefore to the consumer(s) (see  FIG. 2 ). The sensor  21  has at least one sensor diode  21   a . Because of the current carrying capacity, two sensor diodes  21   a  are connected in parallel here. In the event of a current flow from  17 . 1  to  17 . 2  because of the motor controller  6 , a voltage drops at the sensor  21 , which is compared to a comparison value by the comparator, which is connected to an input at the cathode of the sensor diodes  21   a . The comparison value can be generated and can be predetermined in various ways. 
     The comparator  22  outputs a signal or no signal to its output terminal  17 . 3  on the basis of the comparison. 
     The comparator  22  can be provided with an amplifier at its input. 
       FIG. 4  shows a schematic block diagram of a second exemplary embodiment of the load recognition unit  17  of the power supply device  5  according to  FIG. 2 . 
     The second exemplary embodiment differs from the first according to  FIG. 3  in the construction of the sensor  21  and in the type of the comparator  22 . 
     A sensor resistor  21   b  is connected in parallel to the sensor diodes  21   a . Furthermore, the comparator is constructed having a first operational amplifier  22   a  and a second operational amplifier  22   b  connected downstream. The first operational amplifier is used for amplification and the second operational amplifier  22   b  is used as a comparator of the amplified voltage of the sensor  21 . For the comparison, the second operational amplifier  22   b  is connected at its inputs to the output terminal  23 . 2  of a reference unit  23 . In other words, the reference unit  23  is supplied with the operating voltage U 1  or the idle voltage U 2 . The reference unit  23  is, for example, a constant current source. 
     An example of such a constant current source is shown in  FIG. 5  as a schematic circuit diagram of the reference unit  23  of the load recognition unit  17  according to  FIG. 4 . 
     The reference unit  23  is implemented as a constant current source having the input terminal  23 . 1  and the output terminal  23 . 2 . The circuit branches into two parallel current paths at the input terminal  23 . 1 . 
     The first current path is a series circuit of an emitter-collector section of a pnp-transistor T 2 , a resistor R 3 , a collector-emitter section of an npn-transistor T 3 , and a resistor R 2 . 
     The second current path is also a series circuit of a resistor R 1 , an emitter-collector section of a pnp-transistor T 1 , a resistor R 4 , and a collector-emitter section of an npn-transistor T 4 . 
     The transistors T 2  and T 1  are connected such that the collector of the transistor T 2  is connected to the base of the transistor T 1 , wherein the base of the transistor T 2  is connected to the emitter of the transistor T 1 . 
     A connection of the transistors T 3  and T 4  is implemented in a similar manner, in that the base of the transistor T 3  is connected to the collector of the transistor T 4 , and the emitter of the transistor T 3  is connected to the base of the transistor T 4 . 
     A capacitor C and a resistor R 5 , which is parallel thereto, are connected to ground at the output terminal  23 . 2 . 
     In other words, the left part of the circuit, instead of a so-called current mirror of a UBE constant current source, is constructed “mirrored”, i.e., npn transistors are replaced with pnp transistors, on the right adjacent thereto. Therefore, the two circuit parts mutually delimit the current flowing through them in the two “middle” paths. Because both current paths conduct a limited current and no part of the circuit is directly connected to ground, all of the current is “used”. 
     All of the current flowing through all of the circuit elements is constant, wherein the lowest possible power loss is achieved. No part of this current is dissipated “unused” to ground. 
     Also very low currents, e.g., in the microampere range, are possible by way of this circuit according to the invention. This is significant in particular for the idle state in the case of the idle voltage U 2 . 
     The circuit according to  FIG. 5  is also distinguished in that it is discretely constructed using standard components. 
     The control block  19  receives a signal from the load recognition unit  17 , which is assigned to the idle state of the power supply device  5  or the operating state of the power supply device  5 . 
     The control block  19  can be implemented, in a way which is not shown but is easily conceivable in that, for the reference voltage generation of the reference voltage unit (not shown) of the secondary unit, it performs a switchover of the reference voltage. For this purpose, for example, by means of a transistor and a resistor, an existing voltage-determining resistor can be bypassed and/or changed. A control signal is generated by the reference voltage unit, which is supplied via the coupling unit  14  to the control unit  15 . The control unit  15  sets the respective voltage, specifically the operating voltage U 1  and the idle voltage U 2 , on the primary side on the basis of this signal and regulates these voltages in a known manner. In this manner, the power supply device  5  can deliver the operating voltage U 1  for the operating state and the idle voltage U 2  for the idle state. The power supply device  5  is thus implemented as switchable between the operating voltage U 1  and the idle voltage U 2 . 
     A further example of the switchover of the voltages U 1  and U 2  is shown in  FIG. 6  in a schematic block diagram of an exemplary embodiment of a switchover unit  24  of the power supply device  5  according to  FIG. 2 . 
     The switchover unit  24  has an activator  24   a , e.g., a switching transistor, which is connected to a switchover element  24   b , e.g., a relay having a switchover contact  24   c . The activator  24   a  is connected to an input terminal  13 . 2 . 
     The switchover contact  24   c  is connected at its output to the output terminal  13 . 1  of the secondary unit  13 . The operating voltage U 1  is applied to one of the two inputs of the switchover contact  24   c  and the idle voltage U 2  is applied to the other of the two inputs. 
     The idle state is shown in  FIG. 6 . In this case, the switchover contact  24   c  is switched, e.g., deenergized, in such a manner that the idle voltage U 2  is connected via the switchover contact  24   c  to the output terminal  13 . 1 . 
     The display unit  20  is connected to the output terminal  13 . 1  here. By means of a voltage selection device (not shown), the respective state is displayed using an assigned display element. 
     In this exemplary embodiment, the power supply device  5  generates both the operating voltage U 1  and also the idle voltage U 2 . Depending on the signal at the input terminal  13 . 2 , the operating voltage U 1  or the idle voltage U 2  is applied to the output terminal  13 . 1 . 
     The input terminal  13 . 2  is connected in the three-wire embodiment, described briefly above, to the control line  113 . 2  of the motor controller  6 . However, it can also be activated by the load recognition unit  17  using the control block  19 . This also applies for a so-called two-wire embodiment. 
     In the three-wire embodiment, the additional control line  113 . 2  is connected and/or coupled via the motor controller  6  to the manual control  7 . The other two lines or wires of the three-wire embodiment are a positive line and a negative line of the supply cable  111 . In the two-wire embodiment, only positive and negative lines are provided. 
     The idle voltage U 2  can also be generated by means of tapping the transformer of the transformer unit. 
       FIG. 7  shows a schematic block diagram of an exemplary embodiment of generation of an idle voltage U 2  of the power supply device  5  according to  FIG. 2 . 
     The switchover unit  24  is constructed as in  FIG. 6 . In contrast thereto, the switchover contact  24   c  is only used here as a switch-on contact or closer and is connected to the operating voltage U 1 . The output of the switchover contact  24   c  is applied to the output terminal  13 . 1  as in  FIG. 6 . 
     The power supply device  5  continuously generates the operating voltage, both in the operating state and also in the idle state. 
     The idle voltage U 2  is generated by a voltage regulator  25 , it is connected at an input terminal to the operating voltage U 1 . Its output terminal is connected via a feed diode  25   a  to the output terminal  13 . 1 , wherein the cathode of the feed diode  25  is applied to the output terminal, since the positive lines are shown here. In the case of another polarization, the diodes are also to be respectively adapted. In this manner, the idle voltage U 2  is always applied to the output terminal  13 . 1 . 
     If the operating state is set by a signal at the input terminal  13 . 2  by switching over the switchover contact  24   c  of the switchover unit  24 , the operating voltage U 1  is applied in addition to the idle voltage U 2  to the output terminal  13 . 1 . Feedback of the higher operating voltage U 1  on the voltage regulator  25  is prevented by the feed diode  25   a.    
     The display unit  20  is used here having a first voltage display  20   a , e.g., an LED, in the low cross current of the voltage regulator, whereby additional activation is omitted. This first voltage display  20   a  displays the idle voltage U 2 . A second voltage display  20   b , e.g., also an LED, is connected to the output terminal  13 . 1  via a Zener diode (not shown) and only illuminates when the voltage at the output terminal  13 . 1  assumes the voltage U 1  and is higher than the Zener voltage of this Zener diode. Of course, another voltage selection device can also be used. The two voltage displays  20   a  and  20   b  can be implemented as a double LED. Since the first LED  20   a  illuminates continuously and the second LED  20   b  is switched on in addition thereto, it is advisable if these LEDs display different colors. A two-color LED is provided for this purpose. 
     If the idle voltage U 2  in the idle state in the magnitude of approximately 5 V is applied to the motor controller  6 , the electric motor of the linear drive  2  cannot be moved therewith. However, when it is turned on or when the control relay is turned on, a current flows, which does not necessarily result in the attraction of this relay, but induces a voltage drop at the sensor  21  of the load recognition unit  17  and, as described, triggers the power supply device  5  from the idle state into the operating state to deliver the supply voltage U 1  to operate the linear drive  2 . 
     With regard to  FIG. 2 , in which the network circuit breaker  9  is shown, it can—depending on its type and implementation—recognize the idle state of the power supply device  5  in this idle state and perform a release of the household installation. In this case, the test voltage which is then fed to the household installation from the network circuit breaker (e.g., DC voltage at a specific level) can then be sufficient to operate the power supply device  5  in minimal idle operation in the idle state thereof, in such a manner that the idle voltage U 2  is less than 5 V, but is nonetheless sufficient to generate a detectable voltage drop if an actuation is desired in the load recognition unit  17 . 
     The power supply device  5  is then switched over in the above explained manner into the operating state, which has the result that this is recognized by the test voltage of the network circuit breaker  9  and the household installation is switched back to the power supply network  100 . 
     This relates to a plurality of different network circuit breakers  9 . 
     In another embodiment of the power supply device  5 , a switchable and/or variable initial load is provided, which is temporarily connectable in the intermediate circuit  11  or in the input circuit  10  to the terminals of the network cable  110 , in order to ensure an unambiguous recognition of the operating state of the power supply device  5  by the test voltage of the network circuit breaker  9 . This initial load can be, for example, a resistor or a MOSFET switched as a variable resistor or a capacitor, which is disconnected again by the network circuit breaker  9  in the event of completed recognition. This switching off of the initial load can be triggered by the load recognition unit  17 . 
     The above-described exemplary embodiments do not restrict the invention. It is modifiable in the scope of the appended claims. 
     It can thus be conceivable that the motor controller  6  and/or the manual control  7  is/are provided with an additional auxiliary power source. This auxiliary power source can be, for example, a battery/rechargeable battery/a capacitor and can also be used for emergency lowering. 
     The power supply network  100  can also be a direct-current network or a battery/an accumulator. 
     It is conceivable that the switching element  24   b  of the switchover unit  24  can have one or more semiconductor switches.