Abstract:
An electrical circuit for controlling at least one electrical load and at least one function thereof by providing, in the active line of an AC circuit, a modulation switching circuit and a plurality of function keys series-connected with at least with the at least one electrical load and a demodulation unit upstream thereof.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The invention relates to an electrical circuit for the control of a plurality of electrical loads and of the functions thereof. 
         [0003]    It is particularly suitable for upgrading existing electrical circuits in buildings such as, for instance, of ventilation fans and lighting systems which cannot easily be supplemented without extensive measures in terms of the structure and electrical installations. 
         [0004]    2. The Prior Art 
         [0005]    A circuit for controlling an electrical load (for instance, the circuit of a chandelier with a plurality of electric current circuits) is known which by repeatedly actuating one switch allows a few functions to be performed, as by repeated on and off switching and evaluation of the number switching intervals or switching pulses by electronic circuitry. 
         [0006]    Its disadvantage is that the electric load must be provided with such electronic circuitry and that switching five times or more for attaining one state or another is unacceptable. 
         [0007]    Also known is a circuit in which different frequencies or pulse length modulations can be realized by modulating the mains voltage between active line and neutral line or by additional modulation when the phase is at zero. The drawback of such an arrangement is that active and neutral lines must always be present at the switch, which is not the case in simple existing on/off switches in alternating current circuits. 
         [0008]    Furthermore, infrared remote switching circuits are known for the remote control of electrical loads. 
         [0009]    Their disadvantage resides on the one hand in a relatively complex internal or external receiver installed at the apparatus or load and, on the other hand, in the need for a transmitter with a battery as a separate current supply. 
         [0010]    Also, a cable-connected electrical circuit is known for the control of several functions of an electrical load and its functions within a low current net circuit with an active and a neutral line, having, for the control of an electrical load in the active line, a switching unit with several function keys series-connected with one or more electrical loads, with a further switching unit being present ahead of each electrical load. 
         [0011]    Its disadvantage is that in order to energize the diodes for a modulation, active and neutral lines must either be present or they must be installed. This, in turn, requires, for instance during installation of such circuits and, more so, during upgrading existing mains circuits in living, business and function rooms significant time and effort for installing the neutral line. Moreover, such a circuit suffers from a relatively long reaction time. At a minimum signal-to-noise ratio this may result in safety problems and may lead to transmission failure from general net failures. In illumination equipment connected in this manner, for instance, large signal-to-noise ratios may result in flickering (EP 1 066 690 B1). 
         [0012]    Moreover, a system for the zero point data transmission is known for power lines. 
         [0013]    The disadvantage of such circuits is that they require uninterrupted active and neutral lines which cannot be provided in a number of special applications, as, for instance, where simple on/off circuits are present which depend on phase interruptions and which have no neutral line (EP 1,134,910 A2). 
         [0014]    Also, a burst signal transmission system is known for providing electrical circuits. 
         [0015]    Its disadvantage is that for rendering the circuit functional, the transmitters integrated in the circuit always require an EMK by way of an active and a neutral line or battery (EP 0 370 943 A2). 
         [0016]    Furthermore, a cable-connected lamp control system is known in which signals are transmitted by changing the supply voltage. 
         [0017]    Here, too, it is disadvantageous that the signal-modulating current circuit is connected to the active and neutral lines and that for this reason the system is unsuitable for circuits lacking a neutral line (WO 91/030093 A1). 
         [0018]    Finally, a load control system with cable-connected signaling is known. 
         [0019]    Its drawback is that to modulate signals in these systems, there must always be present an active and a neutral line which makes this system unsuitable for circuits without neutral line (GB 2 050 662 A). 
       OBJECT OF THE INVENTION 
       [0020]    It is an object of the invention to provide a cable-connected circuit for the control of a plurality of different electrical loads and/or for the control of several different functions thereof in a single alternating current circuit. 
         [0021]    In this connection, the operating unit for controlling the functions is to be integrated solely in the voltage-carrying line, with neither additional EMK by battery or transformer being required for the function of the operating unit nor the need for connecting a neutral line. 
       SUMMARY OF THE INVENTION 
       [0022]    In the accomplishment of these and other objects the invention provides for an electrical circuit in which, for the control of at least one electrical load  28 , at least one modulation switching unit  21  with a plurality of function keys  12 ,  13 ,  14 ,  15 ,  16 ,  17  is series-connected, by means of terminals A and B to one or more electrical loads  28 ,  28   a,  in an alternating current circuit having an active line  26   b  and a neutral line  26   a,  and a demodulation switching unit  22  is provided ahead of the electrical loads. 
         [0023]    The modulating switching unit  21  with terminals A and B and at least two function keys  12 ,  13 ,  14 ,  15 ,  16 ,  17  is structured such that 
         [0024]    a) within it, between active line  26   b  connected to terminal A and line  26   c  connected to terminal B, there is provided a diode  3  the cathode of which is connected to line  26   b  and the anode of which is connected to a modulating line  26   c,  and 
         [0025]    b) in parallel therewith, between line  26   b  and modulating line  26   c  there are provided a plurality of series-connected homo-poled fast diodes constituting diode group  1  and diode group  2  poled opposite to diode  3 , and 
         [0026]    c) parallel therewith, between diode group  1  and the other diode group  2  as well as the modulating line  26   c,  there is provided a field effect transistor  4  which is by a line  29  is connected to terminals C of double diodes of function keys  12 ,  13 ,  14 ,  15 ,  16 ,  17  as well as to a code generator  8  at one of the contacts PIN  014  thereof such that the field effect transistor  4  is connected in parallel to diode group  2 , with the source being connected to the last cathode of diode group  2 , the drain being connected to the anode thereof and the gate being connected to the function keys  12 - 17  via the double diodes C, D thereof for decoupling, and 
         [0027]    d) a modulation field effect transistor  5  is present between line  26   b  and line  26   c  and also connected, by a line  11 , to the code generator  8  at one of its code output contact PIN  011  such that the modulation field effect transistor  5  is connected parallel to the diode groups  1  and  2  with its source connected to the last cathode of diode group  2 , its gate connected to the data output of the code generator  8  at one of the code output terminals PIN  011  thereof, and 
         [0028]    e) a rectifier diode being provided in line  26   b,  its cathode being connected to a feed line  32  of the code generator  8 , and 
         [0029]    f) a capacitor  7  is present between voltage feed line  32  of the code generator  8  and line  26   c,  and 
         [0030]    g) the voltage feed line  32  is connected to the code generator  8  at one of the positive supply voltage terminals PIN  010  thereof, and 
         [0031]    h) line  26   c  is connected to the function keys  12 ,  13 ,  14 ,  15 ,  16 ,  17  and, by a line  31 , to the code generator  8  at the negative supply voltage contact PIN  09  thereof, and 
         [0032]    i) that, for decoupling, the double diodes of the function keys  12 ,  13 ,  14 ,  15 ,  16 ,  17  are connected, by their contacts D, via lines to the code generator  8  at at least two or more of the control input terminals PIN  06 ,  07 ,  08 ,  09 ,  016 ,  017 ,  018  thereof, and 
         [0033]    j) that the voltage feed line  32  is connected to one of the terminals PIN  010  and another one of the code generator terminals PIN  014  of the code generator  8  by way of a pull up resistor  9  and line  29 , and 
         [0034]    k) external oscillator connection terminals PIN  012  and PIN  013  of the code generator  8  are connected to each other by an external oscillator resistor  10 . 
         [0035]    The demodulation switching unit  22  ahead of the electrical loads  28 ,  28   a  and provided with a power supply unit  23  for maintaining a minimum current for a stand-by function is connected to the neutral line  26   a  and to the modulation line  26   c  from terminal B of the modulation switching unit  21 . 
         [0036]    Within the demodulation switching unit  22  an electronic decoder  24  functioning as a micro processor is connected downstream from the power supply unit  23 . The micro processor is also directly connected to the neutral line  26   a  and, by way of a high-pass filter  25  and/or by a zero point recognition  30  to line  26   c  from terminal B of modulation switching unit  21 . 
         [0037]    At least one electronic or electromechanical power switch  27 ,  27   a  is arranged downstream from the decoder  24 , the power switch  27 ,  27   a  being directly connected in parallel to the neutral line  26   a  and the modulation line  26   c.    
         [0038]    The power switch or switches  27 ,  27   a  are connected to the electrical load or loads  28 ,  28   a  by means of terminals E, F and/or G, H. 
         [0039]    Several modulation switching units  21  may also be interconnected in series. 
         [0040]    The advantages of the invention are that, at relatively low complexity, various further loads and/or functions can be connected to a simple alternating current circuit provided with series-connected on/off switches or two-way switches to an electrical load. The technical complexity in terms of material and labor may thus be significantly minimized. The pole terminals A and B of the lines may be interchanged or exchanged without damaging the system of the electrical circuit. This facilitates installation. It is especially easy to install the circuit in accordance with the invention into existing electrical installations in buildings by leaving the entire simple net in a building unchanged and by only exchanging on/off switches or two-way switches for modulation switching units of the same size and to equip even ceiling vents and/or illumination systems with such a demodulation switching unit. This is of particular advantage, for instance, where a ceiling fan with integrated illumination is to replace an existing fixture since in this manner the illuminating means may be dimmed or switched at different levels of brightness and/or in different numbers and/or where ceiling fans may be simultaneously or separately switched on or off, or where they may be operated at different levels of power or rotational directions. It is also possible to integrate a plurality of switching units in accordance with the invention. To carry out a modulation of bursts on the half-waves of the amplitudes ensures significant immunity from general net malfunctions or other functional failures, such as, for instance, light flickering. The circuit in accordance with the invention is characterized by extremely short reaction times. 
     
    
     
       DESCRIPTION OF THE SEVERAL DRAWINGS 
         [0041]    The novel features which are considered to be characteristic of the invention are set forth with particularity in the appended claims. The invention itself, however, in respect of its structure, construction and lay-out, as well as manufacturing techniques, together with other objects and advantages thereof, will be best understood from the following description when read with reference to the drawings, in which: 
           [0042]      FIG. 1  is a circuit diagram of the modulation switching unit  21  of the function key; 
           [0043]      FIG. 2  is a circuit block diagram of the demodulation circuit unit integrated into the load; and 
           [0044]      FIG. 3  is a schematically shown modulation curve with bursts for switching pulses. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0045]    A ceiling-mounted air exhaust fan combined with lamps is to be connected with active and neutral line to the net by a simple electric system mounted under plaster. Initially, the inventive modulation switching unit  21  with function keys  12 - 17  is series-connected in the line between the ceiling fan as one electrical load  28  and the lamps  28   a  and the net to replace the switch originally provided as an on/off switch. Appropriately associated function keys may be actuated to control several different functions, such as on/of and different revolutions of the ceiling exhaust fan and/or different levels of illumination of the lamp and/or the switching of different numbers of lamps. For this purpose the combination ceiling-mounted air exhaust fan and lamp is provided with a demodulation switching unit  22  and is connected to the existing two-lead net. 
         [0046]    During operation of the circuit electrical power may be switched from 1 W at stand-by operation to several hundred Watts. In a series circuit currents from about 1 mA to several A may result. During a half-wave a low voltage drop is affected across the diode group  1  which feeds the code generator  8  and renders the field effect transistor  4  conductive which shunts the diode group  2 . The diode  6  and the capacitor  7  serve to decouple and buffering of energy. The diode  3  serves to let the opposite half-wave pass. 
         [0047]      FIG. 3  graphically depicts the modulation of the alternating current during signal transmission. 
         [0048]    One or more function keys  12  to  17  are actuated for transmitting a function control signal from the function key switch i.e. the modulation switch unit  21  to the loads  28  and  28   a.  The associated double diode C thus lowers the gate voltage of the field effect transistor  4  by way of the resistor  9  which causes the field effect transistor  4  to open. At the same time the clock system of the code generator  8  (pin  014 ) begins to resonate, with the frequency of the base pulse being determined by the size of the external oscillator resistor  10 . The code generator  8  receives the information about which key or keys have been actuated from contact D of the double diode associated with the respective actuated function key or keys  12  to  17 . The generated code diagrams emitted from the output terminal  011  of the code generator  8  thus control the gate of the field effect transistor  5  which in synchronism with the code signal electrically shunts the diodes of diode group  1  and of diode group  2 . Following the control operation, the diodes of diode group  2  will be shunted by the field effect transistor  4  in order to keep the loss of power as small as possible. On the other hand, the diodes of diode group  2  are required if necessary to increase the degree of modulation or signal-to-noise ratio. Code diagrams appear at pin  011  of the code generator  8  which correspond to a given actuated function key  12  to  17 . The optimum chronological interaction between frequency of the main current circuit, the length of the code and the synchronous gap between the modulation bursts  20  is depicted in the upper half-wave in  FIG. 3 . As a rule, the lower half-wave is not modulated and passes unaltered through the diode  3 . 
         [0049]    To demodulate the modulated half-wave in the demodulation switching unit  22 , the code signal is split by the high pass filter  25  from the low-frequency alternating current and is fed to the decoder  24  which ignores incomplete and faulty modulation bursts  20 . To increase the functionality there will be a succession of several modulation bursts  20 . The decoder  24  will then evaluate several complete transmitted modulation bursts  20  and examine them for uniformity. The electrical power switches  27 ,  27   a  will switch and/or dim individual loads  28 ,  28   a  with dimming resulting from the zero-crossing recognition  30 .