Abstract:
In order to control the luminosity in a room (1) lighted with several light sources (2a . . . , 3a . . . ) or several groups of light sources, a system is used with which the ratio between the light intensities of the individual light sources or groups of light sources can be adjusted or modified, and with which the total luminosity in the room (1) can be adjusted or modified while the ratio between the light intensities of the individual light sources or groups of light sources is kept constant. In particular for this purpose, a control device (7) is integrated in the system and connected to all operating devices (4a . . . , 5a . . . ) of the various light sources (2a . . . , 3a . . . ) to control the power consumption of the individual light sources (2a . . . , 3a . . . ).

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a system and a control device and to a use of the system for controlling the brightness of a room illuminated by a plurality of light sources or a plurality of groups of light sources. 
     DESCRIPTION OF THE RELATED ART 
     More recent lighting systems operate with a plurality of different light sources, in particular direct and indirect light sources. Previously the light sources, such as for example lamps or light fittings, could be dimmed or switched only independently of one another. Consequently it was not possible, or possible only with great difficulty, for example to change the ratio between direct and indirect light and at the same time to keep the overall brightness constant. 
     In practice a light management system of the Applicant is already known which, in the form of an &#34;intelligent&#34; light control system, can individually create different lighting moods in a room and at the same time take into account the prevailing incoming daylight. This system has been described for example in the scientific article &#34;Light Management Brings Numerous Advantages&#34; by C. Tropp in &#34;etz&#34;, Vol. 113, 1992, no. 2, p. 84-87 and in the scientific article &#34;Integrated Light Management Provides Optimal Use of Energy&#34; in &#34;Licht&#34;, Vol. 7-8,/1995, p. 578-580. 
     In the case of the known light management system of the Applicant, the user can activate, switch on and off, and dim individual lights and groups of lights, i.e. create his own lighting moods, via an infrared remote control device or an operating device. By the depression of pushbuttons a plurality of stored lighting moods can be called up in accordance with different office activities. The data transmission to the individual lights and groups of lights is effected by a bus system based on modern two-wire control technology. 
     SUMMARY OF THE INVENTION 
     The object of the present invention is to provide a system and a control device for controlling the brightness of a room with extended adjustment facilities for the user, which permits the coupling of the different light sources or groups of light sources so that the light intensities of the individual light sources or groups of light sources can be controlled adapted to one another in accordance with the user settings, i.e. the user need only set parameters of the overall system and not however the parameters of each individual light source. 
     This object is achieved by a system and control device for controlling the brightness of a room illuminated by a plurality of light sources or a plurality of groups of light sources, wherein the ratio of the light intensities of the individual light sources or groups of light sources can be set or changed and additionally the overall brightness of the room can be set or changed while maintaining a constant ratio of the light intensities of the individual light sources or groups of light sources. 
     A possible application of the system according to the invention consists in its use in a light fitting comprising at least two separately actuatable lighting means, where one lighting means serves for the direct lighting of the room and a further lighting means serves for the indirect lighting of the room. 
     Further developments and embodiments of the invention are described in the further detail herein. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The construction and mode of functioning of an exemplary embodiment of the invention will now be explained making reference to the drawing wherein: 
     FIG. 1 schematically illustrates an exemplary embodiment of the system according to the invention; 
     FIG. 2 is a block circuit diagram of a simplified system according to FIG. 1; 
     FIGS. 3a, b show two diagrams in explanation of the logic relationship between the control values of the control device and the brightness; 
     FIGS. 4a, b illustrate two diagrams in explanation of the mode of functioning of the system according to the invention and 
     FIG. 5 is a flow diagram in explanation of the mode of functioning of the system according to the invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     An exemplary embodiment of the system according to the invention is schematically illustrated in FIG. 1. A room 1 to be lighted contains a plurality of groups of light sources; a first group consists of two direct light sources 2a and 2b in the form of commercially available ceiling lamps while the second group consists of the direct light source 2c in the form of daylight entering through a window of the room 1, the light intensity of which can be set for example by adjustable slatted blinds, and the third group consists of three indirectly radiating light sources 3a, 3b and 3c in the form of indirectly radiating wall lamps. In place of the light sources used in this exemplary embodiment, in principle it is also possible to use any conceivable type of light source whose light intensity can be changed. 
     The direct light sources 2a and 2b are connected to the associated operating devices 4a and 4b, the slatted blind for regulating the incoming daylight is connected to the associated operating device 4c, and the indirect light sources 3a, 3b and 3c are connected to the associated operating devices 5a, 5b and 5c. All the forementioned operating devices 4a, . . . and 5a, . . . of the various light sources in the room 1 are connected via a bus 6 to a control device 7. Via the bus 6 this control device 7 controls the power consumption of the individual operating devices 4a, . . . and 5a, . . . and thus controls the light intensities of the individual light sources 2a, . . . and 3a, . . . in the room 1. 
     Two operating elements 8a and 8b are arranged on the control device 7. These operating elements 8a and 8b enable the user of the system to set and change the parameter &#34;volume&#34;, i.e. the overall brightness of the room 1, and the parameter &#34;balance&#34;, i.e. the ratio between the light intensities of the direct and indirect light sources. 
     The operating elements 8a and 8b can consist for example of known double control switches for lighter/darker adjustment and for on/off switching, and of known knob control switches for setting the ratio between the light intensities. In place of the forementioned conventional installation technology (control switches, potentiometers etc.) the parameters can also be set or changed by the transmission of digital data to the control device. 
     The operating elements 8a and 8b need not necessarily be arranged directly on the control device 7 but can equally be arranged on an external operating unit connected to the control device 7 via an electric connection or radio signals for the transmission of the set values &#34;volume&#34; and &#34;balance&#34;. 
     It can also be seen from FIG. 1 that the control device comprises a non-volatile memory 9 in which all the configurations can be stored. These configurations also include the preset parameters, which are required in addition to the parameters &#34;volume&#34; and &#34;balance&#34; set via the operating elements 8a and 8b, for controlling the light intensities. These preset parameters can include: the sensitivity of the human eye, the dependency of the light intensity upon the power impressed upon the light source, the lighting technology properties of the light fitting or the reflective properties of the room to be illuminated. The use of these preset parameters will be explained later in the description. 
     FIG. 2 is a simplified diagram of the above described system in the form of a block circuit diagram. In place of the six operating devices 4a, . . . and 5a, . . . according to FIG. 1, here only two operating devices 4 and 5 are connected to the bus 6 of the control device 7. The light intensity of the direct light source 2 of the operating device 4 is controlled via the channel 1 of the control device 7 and the light intensity of the indirect light source 3 of the operating device 5 is controlled via the channel 2 of the control device 7. 
     Via the channels 1 and 2, from the control device 7 the corresponding power consumption control values S 1  and S 2  are fed to the operating devices 4 and 5. In FIGS. 4a and 4b these control values S 1  and S 2  for channel 1 and channel 2 have been plotted as a function of the parameter &#34;volume&#34;, i.e. the overall brightness, in a logarithmic diagram. 
     The logic relationship between the control values and the brightness, which leads to the indicated control value characteristics of channel 1 and channel 2, will be explained in the following making reference to FIG. 3. In the diagram in FIG. 3a the sensitivity to brightness H of the human eye is plotted over the light intensity L of a light source. The human eye is more sensitive to the difference in brightness between two light sources of weak light intensity than the difference in brightness between two light sources of strong light intensity. A logarithmic relationship between H and L results. 
     If, in place of the linear axial scaling of L, logarithmic plotting over L is selected, in the diagram a straight line occurs as the relationship between H and L. In FIG. 3b the two axes have now been transposed, i.e. the brightness sensitivity H has been plotted as the abscissa of the coordinate system and the light intensity has been plotted with logarithmic scaling as the ordinate of the coordinate system. The parameter &#34;volume&#34; V of the control device 7 corresponds to the brightness sensitivity H and the control value S corresponds to the logarithm of the light intensity L. This leads to a characteristic of the control value S over the parameter &#34;volume&#34; V in the form of a straight line which generally is not an originating line. 
     For the two channels 1 and 2 the respective control value characteristics of the control values S 1  and S 2  have now been entered in the diagrams of FIGS. 4a and 4b. The distance between the two parallel characteristics of the control value S 1  of channel 1 and the control value S 2  of channel 2 is determined by the parameter &#34;balance&#34;, i.e. by the ratio of the light intensities of the two light sources 2 and 3. 
     The value ranges for the two control values S 1  and S 2  are between 0 and 255, while the value range of the parameter &#34;volume&#34; is between 0 and 255 and the value range of the parameter &#34;balance&#34; is between -255 and 255. 
     FIG. 4a now illustrates what occurs when the user changes the parameter &#34;volume&#34; via the operating element 8a. Upon the change in the parameter &#34;volume&#34;, the light intensities of the two channels are changed in the same direction, at which time the user is unable to change the ratio between the light intensities. On account of the logarithmic characteristic this is the case whenever the control value difference (S 1  -S 2 ) between the two channels is constant. Upon a change in the parameter &#34;volume&#34; by dV, the two control values change by the same amount and in the same direction by dS 1  and dS 2 . 
     FIG. 4b illustrates the situation in which the user changes the parameter &#34;balance&#34; via the operating element 8b. Upon the change in the parameter &#34;balance&#34;, the one channel is to be reduced by precisely the light intensity value by which the other channel is increased, at which time the user is unable to change the overall brightness. On account of the logarithmic characteristic this is the case whenever the control value of the one channel is reduced by the value by which the control value of the other channel is increased. In the event of a change in the parameter &#34;balance&#34; by dB, the two control values thus change by the same amount in the opposite direction by dS 1  and dS 2  =-dS 1 . 
     The precise calculation of the change in the control values dS 1  and dS 2  upon a change in the parameters by dV and dB will be explained in the following making reference to FIG. 5. FIG. 5 is a flow diagram for the calculation of the new control values S&#39; 1  and S&#39; 2  on the basis of parameter changes dV N  and dB N  by the user. The calculation comprises the following steps: 
     A) Parameterization of the changes dV N  and dB N  input by the user by a non-linear coordinate transformation using the above indicated preset parameters in order to obtain suitable parameter changes dV and dB for the calculation of the control values S&#39; 1  and S&#39; 2  : ##EQU1## wherein P is a matrix which takes into account the preset parameters. B) Calculation of the changes in the control values dS 1  and dS 2  on the basis of the parameterized changes dV and dB: 
     
         dS.sub.1 =dV-dB and dS.sub.2 =dV+dB                        (2) 
    
     and calculation of the new control values S&#39; 1  and S&#39; 2  : 
     
         S&#39;.sub.1 =S.sub.1 +dS.sub.1 and S&#39;.sub.2 =S.sub.2 +dS.sub.2(3) 
    
     C) Checking whether the two control values S&#39; 1  and S&#39; 2  fall in the permitted value range between 0 and 255. If this is the case, the control values S&#39; 1  and S&#39; 2  just calculated can be adopted as new control values of the system. If at least one of the two control values S&#39; 1  or S&#39; 2  falls outside the valid value range between 0 and 255, a corrective calculation must be performed in accordance with step D). 
     D) Corrective calculation whereby the control value S&#39; i  (i=1 or 2) falling outside the valid value range between 0 and 255 is set at a value inside this value range: 
     
         dV&#39;=-(S&#39;.sub.i -D)/2 and dB&#39;-+(S&#39;.sub.i -D)/2              (4) 
    
     wherein D is the value of an upper and lower dimming limit which is not to be over- or undershot during the operation of the light sources. This value D can also assume the limit values of the value range 0 and 255 but must not lie outside of the value range between 0 and 255. In particular in the case of the lower dimming limit, a value D&gt;0 is often selected, as will be explained later in the description. 
     E) If a corrective calculation has been performed in accordance with step D), the parameters are now reset such that a further calculation can be made in accordande with step B): 
     
         dV-dV&#39;, dB=dB&#39;, S.sub.1 =S&#39;.sub.1, S.sub.2 =S&#39;.sub.2       (5) 
    
     The corrective calculation (4) in step D) is conceived such that the loop comprising steps D) and E) need be run through only once, i.e. the control values S&#39; 1  and S&#39; 2  fall within the valid value range after a maximum of one correction. 
     To clarify the above described calculation of the new control values S&#39; 1  and S&#39; 2 , in particular in the case of a corrective calculation, this calculation will now be performed in the form of a concrete numerical example. 
     It will be assumed that the start values S 1  =210 and S 2  =120 have been selected as control valus for the channels 1 and 2; the upper dimming limit will be assumed to correspond to the upper limit of the value range, thus D=255. The changes input by the user following the parameterization (step A) in accordance with equation (1) will be assumed to be dV=+80 and dB=0, i.e. it will be assumed that the user wishes to increase the overall brightness of the room 1 (dV&gt;0) while maintaining a constant ratio of the light intensities (dB=0). 
     In accordance with equation (2) in step (B) the changes in the control values result in 
     
         dS.sub.1 =+80-0=+80 and dS.sub.2 =+80+0=+80. 
    
     from which, in accordance with equation (3), the values of the new control values are calculated: 
     
         S&#39;.sub.1 =210+80=290 and S&#39;.sub.2 =120+80=200. 
    
     The result of the checking of the two control values S&#39; 1  and S&#39; 2  in step C) is that the first control value S&#39; 1  lies outside of the valid value range (S&#39; 1  &gt;255). The control values S&#39; 1  and S&#39; 2  which have just been calculated thus cannot be adopted as new control values and a corrective calculation in accordance with step D) must be performed. 
     In accordance with equation (4) the corrected changes dV&#39; an dB&#39; result in 
     
         dV&#39;=-(290-255)/2=-17.5 and dB&#39;=+(290-255)/2=+17.5. 
    
     Now in step E) the calculated control values S&#39; 1  and S&#39; 2  and the corrected changes dV&#39; and dB&#39; are set as start values and step B is performed again in order to calculate the new valid control values. The calculation in accordance with equations (3) and (4) now yields: 
     
         dS.sub.1 =-17.5-(+17.5)=-35 and dS.sub.2 =-17.5-(-17.5)=0,S&#39;.sub.1 =290+(-35)=255 and S&#39;.sub.2 =200+0=200. 
    
     The new control value S&#39; 1  now lies within the valid value range so that the last calculated control values S&#39; 1  =255 and S&#39; 2  =200 can now be fed via the two channels 1 and 2 to the associated operating devices 4 and 5 respectively. 
     The values of the lower and upper dimming limit D are configured in the non-volatile memory 9 during the production. On the basis of the selection of the lower dimming limit as D&gt;0 or D=0, it is possible to predetermine the type of on/off switching. 
     In the former case D&gt;0 the light sources of the two channels are commonly switched on and commonly switched off. This means that the channel with the lower control value remains at the lower dimming limit and does not change to the control value 0 until the control value 0 also occurs for the other channel, and that the channel with the lower control value is set at the lower dimming limit upon the switching on of the other channel and remains not switched off. 
     In the other case in which D=0, the light sources are switched on and off separately from one another in general, i.e. except when B=0. This means that the channel with the lower control value is switched off when the control value 0 occurs for this channel while the other channel with the higher control value remains switched on, and that the channel with the lower control value remains switched off upon the switching on of the other channel until a control value greater than 0 also occurs for this channel. 
     In addition to the example of use of the system according to the invention illustrated in FIGS. 1 and 2, a further possible application consists in the use of the system and control device in a light fitting comprising at least two separately actuatable lighting means. Here at least one lighting means serves for the direct lighting of the room and at least one further lighting means serves for the indirect lighting of the room so that via the operation of the control device of the light, similarly to the room lighting in accordance with FIG. 1, the user is able to adjust both the overall brightness of the room and also the ratio between the light intensities of the direct and indirect lighting.