Abstract:
A circuit provided with an optoelectronic display unit. For discrete display of the settings of a regulating/control unit, said circuit comprises at least one detection element for detecting the actuation of an object in order to modify the settings of the regulating/control unit, whereby the detection element delivers an output signal corresponding to the desired modification. Several luminous diodes ( 1   a   , . . . , 1   n ), which are essentially arranged next to each other in a row and which emit luminous radiation, are used as display elements. A control device controls at least one of the luminous diodes ( 1   a   , . . . , 1   n ) according to the output signal in order to display the respective setting, in addition to the regulating/control unit for modification of the setting. In order to produce a quality display and operator unit, at least two receiver elements which are sensitive with respective to the luminous radiation of the luminous diodes ( 1   a   , . . . , 1   n ) are provided, acting as detection elements in order to detect the luminous radiation reflected by at least one luminous diode ( 1   c ) and by an object ( 2 ), and the control device controls at least one of the luminous diodes in addition to the regulating/control unit as a result of the output signal, which is formed according to the movement of the object relative to the luminous diode ( 1   c ) emitting luminous radiation, according to the movement of said object.

Description:
REFERENCE TO RELATED APPLICATIONS  
         [0001]    The present application claims the priority of the German patent application 101 46 996.9, filed on 25.09.2001, the disclosure content of which is hereby expressly also made the subject matter of the present application.  
         FIELD OF THE INVENTION  
         [0002]    The invention relates to a circuit comprising an optoelectronic display unit.  
         BACKGROUND OF THE INVENTION  
         [0003]    In the field of operator control elements, displays formed e.g. by a series of LEDs are known, which indicate a set value. This may be a row of LEDs, i.e. light-emitting diodes, which are arranged side by side and of which one element emits light and indicates an actual value. As a rule, the luminescent elements arranged in a row are suitably labelled to enable an association with a quantity such as e.g. a display in “dB” for volume control. Changeover to another value is effected mechanically e.g. by means of momentary-contact switches. Generally, to increase and reduce the value one mechanical momentary-contact switch is used in each case. A change of value effected by pressing the appropriate momentary-contact switch is indicated by the appropriate LED in the row by virtue of a positional variation in the display.  
           [0004]    [0004]FIG. 1 shows such an LED display known from the prior art, wherein the position of the LED and hence also e.g. the “volume level” may be adjusted by means of the plus and minus keys. The advantage of such an arrangement lies in the clear overview of the set position and in the spontaneous operator controllability. The drawback is, however, the need for mechanical cutouts in the operator control panel and the provision of appropriate keys.  
           [0005]    From DE 43 36 669 C1 a touch panel is known, comprising optical sensors, which are associated with different actuating surfaces and react to the shading of a sensor surface corresponding to the size of a finger. The acquisition of the ambient light is therefore the information to be processed. Usually, for this purpose, a means other than the means used to generate a light signal is used. For indicating a value that is to be displayed an additional lighting display unit is required. The opto-receivers and opto-transmitters may be operated exclusively in a pulsed manner, which is disadvantageous for the discrete alteration of a value that is to be set (cf. also DE 40 07 971 A1 in the infrared range).  
           [0006]    The acquisition of information, which is needed to vary a value to be set at an operator panel, may also be effected by means of touch-sensitive switching devices according to DE 694 19 735 T2 or DE 36 85 749 T2, which through the acquisition of a capacitance correspond with the optical display unit to be operated; because of its sensitivity to moisture, however, this use is restricted to specific areas.  
           [0007]    DE 39 32 508 A1 shows a conventional reflection light barrier without a discrete control facility. Transmitters and receiving elements always have to be provided separately. DE 28 24 399 A1 discloses an optical switch with separate transmitters and receivers. In both cases, the light barriers formed thereby are only the means of setting the display and not the display means itself.  
           [0008]    From U.S. Pat. No. 5,327,160 a touch fader as a remote control is known, which may be operated only in the switching mode.  
           [0009]    Arrangements of light-emitting diodes, which may be used in turn both as a light-emitting and as a light-receiving element and the optical signal of which directly reproduces the value to be displayed, which may moreover be controlled so as to follow the movement of a finger or of a comparable body in order thereby to reach the value to be set, but which may also be operated in clocked manner and thus spontaneously, are not known from the prior art.  
         SUMMARY OF THE INVENTION  
         [0010]    Proceeding from this background art, an advantage of one or more of various embodiments of the invention is to provide an advantageous display- and operator control unit and, for operator control of such a regulating/adjusting unit, to utilize the display itself as an operator control element, wherein both discrete regulation of values to be set and clocked handling is possible.  
           [0011]    In an exemplary embodiment, a circuit with an optoelectronic display unit for the discrete display of the setting of a regulating/adjusting unit includes: at least one detection element for detecting the actuation of the regulating/adjusting unit by means of a body for changing the setting of the regulating/adjusting unit, wherein the detection element upon actuation supplies an output signal corresponding to the desired change; a plurality of light-emitting diodes disposed substantially side by side in a row and emitting optical radiation, the light-emitting diodes being formed as display elements of the display unit; a control device, which in dependence upon the output signal produced by the detection element controls at least one of the light-emitting diodes to display the respective setting as well as the regulating/adjusting unit to change the setting; wherein the control device controls at least one of the light-emitting diodes, the detection elements as well as the regulating/adjusting unit to follow the movement of the body on the basis of the output signal, which is formed in dependence upon the movement of the body relative to the light-emitting diode that is emitting optical radiation, and that either at least two receiving elements are provided, which are sensitive to the optical radiation of the light-emitting diodes and which as the detection elements detect the optical radiation emitted by at least one light-emitting diode and reflected by the body, or that at least one receiving element is provided, which is sensitive to the optical radiation of the light-emitting diodes and which as the detection element detects the optical radiation emitted by at least two light-emitting diodes and reflected by the body, wherein in both cases the control device, as soon as the control device because of the output signal advances the display unit in one direction to one of the next light-emitting diodes, also advances in the same direction the receiving element(s) being adjacent to the light-emitting diode emitting the optical radiation.  
           [0012]    With the display unit formed by the light-emitting diodes receiving elements are associated in such a way that no separate mechanical keys are necessary. For operator control of such a regulating/adjusting unit, therefore, the display itself becomes the operator control element. There is therefore no need for either keys or cutouts for such keys. This, on the one hand, reduces the cost of manufacturing such an operator control unit and, on the other hand, enables the regulating/adjusting unit to be disposed under a closed, protective surface so that it—easy to clean and insensitive to dirt—has a long useful life and may be used for many applications.  
           [0013]    In another exemplary embodiment, the light-emitting diodes are not only a display element but temporarily in turn a transmitting and receiving element, thereby making it possible further to reduce the circuit engineering outlay. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    The invention is described in detail below with reference to the accompanying drawings. The drawings show:  
         [0015]    [0015]FIG. 1 a regulating/adjusting unit according to prior art,  
         [0016]    [0016]FIG. 2 a block diagram of a regulating/adjusting unit according to prior art,  
         [0017]    [0017]FIG. 3 a diagram for selection of an LED as a display- and operator control element,  
         [0018]    [0018]FIG. 4 a reflecting element usable for operator control above an LED row,  
         [0019]    [0019]FIG. 5 an arrangement for realizing a sensitive LED row,  
         [0020]    [0020]FIGS. 6, 7 the circuit according to the invention,  
         [0021]    [0021]FIGS. 8 a - 8   e  signal characteristics during momentary contact with an LED,  
         [0022]    [0022]FIG. 9 a circuit for selection of an outer-lying LED,  
         [0023]    [0023]FIG. 10 phases and amplitude relationship of the analogue output signal S 17  of the comparator  16 ,  
         [0024]    [0024]FIG. 11 the analogue output signal S 17  over time during changeover,  
         [0025]    [0025]FIG. 12 a circuit for increasing the changeover reliability,  
         [0026]    [0026]FIGS. 13, 14 the analogue output signal S 17  over time across the output of the buffer B with and without zero referencing,  
         [0027]    [0027]FIG. 15 the signal V 1 , derived from the analogue output signal S 17 , over time at the window comparator according to FIG. 14 with associated LED selection,  
         [0028]    [0028]FIG. 16 a circuit according to FIG. 12 with a hysteresis detector,  
         [0029]    [0029]FIG. 17 a signal characteristic of the output signal S 17  with simultaneous use of the hysteresis detector,  
         [0030]    [0030]FIGS. 18 a - 18   c  arrangements for use as a volume control, for processing a data stream or as a position display,  
         [0031]    [0031]FIG. 19 a mechanical sliding control according to prior art,  
         [0032]    [0032]FIGS. 20, 21 arc-shaped and circular regulating/adjusting units according to the invention,  
         [0033]    [0033]FIG. 22 a regulating/adjusting unit in the form of a virtual turning knob,  
         [0034]    [0034]FIG. 23 a regulating/adjusting unit with two transmitting elements,  
         [0035]    [0035]FIG. 24 a complete block diagram. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0036]    The invention is described in detail below with reference to the accompanying drawings. However, the embodiments are merely examples, which do not restrict the inventive concept to a specific arrangement.  
         [0037]    In the prior art, the switching assignment for an adjusting unit according to FIG. 1 comprises according to FIG. 2 a counting device  91 , the instantaneous state of which is determined by the key functions T 1  (e.g. +key) and T 2  (e.g. −key). Each time the keys T 1  and T 2  are actuated, the counting device  91  counts one value increment upwards and/or downwards and passes this information on to the display driver  92 , which allows the LED corresponding to the set value to emit light. Parallel thereto, the set value is passed on to the control apparatus and/or the value regulator  93 . This value regulator  93  regulates e.g. the amplitude of an analogue audio signal  94 / 95  in accordance with the set value  96 . Thus, always at least one external control signal T 1  or T 2  is required for setting the value. The LEDs  1   a . . . n  merely display the set value and have no other function.  
         [0038]    The invention described below dispenses with indirect information transfer with the aid of the keys T 1  and T 2 , with the result that the information is received up and converted directly by the LED display.  
         [0039]    To achieve this, the bifunctionality of the light-emitting diodes is used: these may emit light, when they are correspondingly driven by a current, or produce power and/or current, when they are correspondingly illuminated. If then, for example, low-crosstalk wiring is selected, a light-emitting diode may be operated sequentially as a transmitter and as a receiver. In principle, the same function is however realizable also by using alternative receiving elements such as e.g. photodiodes parallel to the light-emitting LEDs. In this case too, because of the overall size the display is still simultaneously the operator control element, even when the light-emitting diodes do not have the above double function.  
         [0040]    [0040]FIG. 3 shows such wiring, where the light-emitting diodes (LEDs) operate sequentially in respect of time as transmitters and receivers. In the phase t x  the switch Sa, for example, is closed and connects the output of the clock generator  100  to the LED via the series resistor R 10 . The clock generator is operated e.g. at a frequency of 10 kHz. In this phase the switch Sb is open and disconnects the LED from the amplifier  300 . The inverter  200  is used only to invert the control signal Sts. In phase t y  the switch relationship is reversed and the switch Sa disconnects the LED from the clock generator  100 , while switch Sb connects the LED to the amplifier  300 .  
         [0041]    To present a display, generally at least one element of an LED row will emit light, while all of the others are switched off. Naturally, there are however also constructions where all of the display elements up to the set value are switched on, i.e. form a light strip. If the light-emitting element of the LED row emits its light, not as constant light by virtue of continuous selection, but in a pulsed manner e.g. by means of a 10 kHz rectangular-pulse signal, it nevertheless appears to the naked eye as a continuously light-emitting element. At the same time, it may however be used as a transmitting element of a sensor apparatus. Adjacent LEDs, which are correspondingly connected as receivers, may namely receive the signal of the pulse-controlled LED when a reflecting element, e.g. a finger  2 , is situated above the LED that is emitting the pulsed light.  
         [0042]    Given a positioning of the reflecting element centrally above the transmitting LED  1   c  according to FIG. 4, the emitted light is reflected uniformly onto the adjacent LEDs  1   b  and  1   d.  In said case, a pane  37 , which is translucent with regard to the respective radiation emitted by the LED may also be situated between the LEDs and the reflecting element, e.g. a finger  2 . As radiation, in particular, all optical radiation in the visible range but also in the range invisible to the human eye is suitable. Given symmetrical reflection, there is also across the outputs of the amplifiers  5  and  6  an amplitude of equal size in the output signals  7 ,  8 .  
         [0043]    [0043]FIG. 5 shows an arrangement for realizing the sensitive LED row. The light-emitting diodes  1   a  . . .  1   n  may be utilized both in the transmitting and in the receiving range. For the transmitting mode of the light-emitting diodes  1   a  . . .  1   n,  connectable driver stages  3   a  . . .  3   n  are provided and, for the receiving range, connectable amplifiers  2   a  . . .  2   n  are provided. The signal distribution stages  44  and  45  are suitably positioned by the setting of the position counter  23 . The direction decision unit  47  detects the direction of motion of the reflecting element and decides when a specific value of the position deviation has occurred. If this was the case, position counter  23  is correspondingly activated and counts one position value upwards or downwards. At the same time, the direction decision unit  47  may first of all establish whether there was “momentary contact” of the light-emitting element before reacting to movement e.g. of the finger  2 , or whether it was a case of inadvertent touching of the sensor-active surface and hence no reaction of the LED display is to occur.  
         [0044]    The position counter  23  via a control unit  24  (FIG. 7) controls both the selection of the transmitter elements and the receiving mode. In each case, therefore, a single LED is selected as a transmitter, while at least the LEDs adjacent to it—e.g. the next or next but one LED—are connected as receivers. However, it is of course also possible for two LEDs to transmit simultaneously and for the LED disposed between the two light-emitting LEDs to be connected as a receiver. In principle, it is also possible for separate receiving elements to be arranged staggered or offset relative to the LEDs, e.g. in a row parallel to the LEDs. At the position counter  23 , moreover, the control signal Sts for influencing any desired regulating/adjusting unit  30  is tapped.  
         [0045]    [0045]FIG. 6 shows a circuit for direction detection, momentary contact recognition and detection of the horizontal movement of the reflecting element in relation to the light-emitting LED, here LED  1   c.  Here, LED  1   c  is selected by the clock generator  100  and is emitting light, which is reflected by the finger  2 . The adjacent LEDs  1   b,    1   d  receive a reflection component caused by the finger  2 . DCCs  3 ,  4  form an operating point adjustment for the LEDs as receivers. With the aid of these DCCs (DC compensation), even in the event of intense extraneous light the LEDs are prevented from becoming saturated. The construction of such an operating point adjustment is known e.g. from DE-PS 44 31117.  
         [0046]    For the sake of simplicity the changeover switches of the LED selection are not shown in the drawing. Two amplifiers  5  and  6  of an identical type amplify the low output signals of the LEDs  1   b  and  1   d  adjacent to the transmitter to a value that is easy to process further. Before both output signals  7  and  8  are combined in the summing stage  10 , the inverting circuit  9  inverts one of the two signals.  
         [0047]    Given the absence of a reflecting element, such as a finger  2 , or given the presence of one but with symmetrical reflection of the transmitted signal back into LEDs  1   b,    1   d,  no signal occurs across the output of the summing stage or because of the inverting circuit  9  two signal components, which for instance arise but are of equal magnitude, cancel each other out so that there is likewise no signal across the output of the summing stage  10 . Given the presence of a reflecting element and simultaneous asymmetry relative to the transmitting LED  1   c,  e.g. if the finger  2  has shifted slightly to the right, at the LED  1   d  owing to intensified reflection a greater signal develops than at the LED  1   b.  This leads, across the output of the summing stage  10 , to a signal with a clocked modulation with corresponding sign of the phase in relation to the signal of the clock generator  100 . The magnitude of the signal is determined by the horizontal position of the finger  2  in relation to the transmitting LED  1   c.    
         [0048]    The output signal of the summing stage  10  is supplied for further evaluation to a synchronous demodulator  11 . The control signal for the synchronous demodulator is tapped from the clock generator  100 . It corresponds substantially to the transmitted signal but takes into account the phase displacements arising in the amplifiers  5  and  6 . The synchronous demodulator  11  splits the output signal of the summing stage  10  once more into two individual signals  12 ,  13  associated with the LED  1   b  and  1   d  respectively. For a clear decision about the direction of motion and/or position of the finger  2  relative to the transmitting element  1   c,  the two individual signals  12  and  13  are compared with one another in the comparator  14 . The digital output signal S 15  of the comparator  14  provides clear information about the position of the reflecting element, in relation to the transmitting element  1   c,  i.e. about whether the finger  2  is situated to the right or left of the centre of the LED  1   c.    
         [0049]    In order to decide, from which position variation an advancing of the light-emitting LED analogous to the movement of the finger  2  is to occur, the output signals  12  and  13  of the synchronous demodulator  11  are compared in a suitably analogue-operating comparator  16 , e.g. with an operational amplifier. The analogue output signal S 17  corresponds to the horizontal deviation of the finger from the centre of the transmitting LED  1   c.  From this output signal during further signal processing the switching signal for the position counter  23  (FIG. 7) is obtained. The digital output signal S 15  is used to define the appropriate counting direction for the position counter  23 . In the embodiment, a counting direction towards higher values may advance the transmission driver from the LED  1   c  to the LED  1   d,  with a simultaneous changeover of the amplifiers  5  and  6  from LED  1   b  and  1   d  to  1   c  and  1   e.    
         [0050]    To prevent unintended adjustment owing to inadvertent contact, prior “momentary contact” of the light-emitting element for further activation of the adjustment facility may be provided. For this purpose, information has to be obtained from the vertical movement of the finger  2  towards or away, respectively, from the light-emitting element. This information may be gathered from the summing stage  18 , in which both signals of the receiving LEDs are summed. A synchronous demodulator  19  correspondingly evaluates the summed signal and said signal is available via the buffer stages  20  as an analogue distance signal S 21 .  
         [0051]    [0051]FIG. 7 shows the evaluation of the signals S 21 , S 15  and S 17 . A window comparator  22  supplies an output signal S 22  when the output signal S 17 , which is in fact an analogue value of the horizontal position of the finger in relation to the transmitting LED, exceeds or falls below a value preselected in the window comparator  22 . This value is reached when the reflective element, i.e. the finger  2 , is moved some distance laterally of the centre of the transmitting element (LED  1   c ) towards the adjacent receiving element (LED  1   b  or  1   d ), even if the distance is less than half the distance between two adjacent elements. The output signal S 22  of the window comparator  22  is supplied as a clock signal to the position counter  23 .  
         [0052]    The decision, whether the position counter  23  is to count upwards or downwards, which corresponds to a “shift” of the light-emitting LED to the left or to the right, is taken from the output signal S 15  of the comparator  14 . The output signal S 23  of the position counter  23  is supplied to the control unit  24 . The control unit  24  determines the position—corresponding to the numerical value of the output signal S 23 —of the transmitting LED and its at least two indirectly or directly adjacent receiving LEDs or receiving elements.  
         [0053]    In principle, the light-emitting LED is not to change position simply as a result of a hand being inadvertently wiped over the LED. Rather, first the position sensitivity is to be activated manually before the light-emitting LED “travels along” with the moving finger. For this purpose, the output signals  7 ,  8  are combined in the summing stage  18  and synchronously demodulated and the distance signal S 21  thus obtained is conditioned in a suitable evaluation circuit  25  in such a way that e.g. a shift of position is enabled only after “momentary contact” with the light-emitting LED has been effected once or twice.  
         [0054]    The momentary-contact recognition apparatus preferably recognizes as momentary contact a pattern of motion, which comprises the approach of a body, the sudden braking of the body against a touched surface and a dwelling on the surface for a preselected time t 28 .  
         [0055]    To this end, in the embodiment the distance signal S 21  is passed through the high-pass filter  26 , which allows through only the higher-frequency spectral components of the distance signal S 21 . These signal components occur only in the event of a rapid variation in the distance signal S 21  according to FIG. 8 a.  The sudden braking of the finger on a translucent surface above the LED row may therefore lead to an output signal S 26 , a signal differentiated from the distance signal S 21 . If this output signal S 26  according to FIG. 8 b  exceeds a predetermined value Ref, the comparator  27  supplies a digital output signal S 27  (FIG. 8 c ) to a first timer  28  with a timer time t 28  of several hundred milliseconds to seconds (FIG. 8 d ). At the end of this short time, timer  29  according to FIG. 8 e  is started. Its running time is several seconds. The output signal S 29  enables the position counter  23 . A variation of the counter content then retriggers (rt) the timer  29 . If the position of the light-emitting LED is not varied within the running time t 29  of the timer  29 , the time t 29  elapses and the position counter  23  is disabled again. This circuit arrangement prevents the position of the light-emitting LED in the LED row from being varied by an unintentional movement. It is only after “momentary contact” that the position of the light-emitting LED may be shifted by renewed contact with the light-emitting LED and displacement of the finger.  
         [0056]    At this point any conceivable circuit arrangement may be inserted, i.e. including counter arrangements, which also enable the position counter  23  only after repeated momentary contact with the light-emitting LED. From WO 01/54277 A1 an arrangement—which is e.g. preferentially usable here—is known, in which a function is switched only if a finger quickly touches (has momentary contact with) the translucent surface above an LED and remains relatively still there for at least a specific time, e.g. 200 ms.  
         [0057]    The digital output signal S 23  of the position counter  23  moreover controls the control unit  24 . In the control unit  24 , the transmitted drive signal is suitably distributed to the LEDs and the two amplifier inputs of the amplifiers  5 ,  6  (FIG. 6) are distributed to the LEDs adjacent to the transmitting diodes. The output signal S 23  of the position counter  23  (FIG. 7) may further be used to control any desired value controller of a regulating/adjusting unit  30 , e.g. for volume control.  
         [0058]    If the light-emitting LED is “shifted” into one of the two end positions, it is however no longer possible for the at least two adjacent LEDs to serve as receivers, but only one. In said case, in the event of parasitic reflections e.g. at the translucent surface, the single receiving LED, e.g. LED  1   a,  receives a signal similar to that of a “shifted” finger. In extreme cases, this unwanted signal would lead to the selection repeatedly skipping back from LED  1   a  to LED  1   b.    
         [0059]    To prevent this, upon selection of LED  1   a  a simulated “light signal” is presented to the amplifier  6  (FIG. 6). FIG. 9 shows the corresponding changeover in said respect. Switches S 1 , S 2  and S 3  are activated via the control unit  24  by the control signal S 23  of the position counter  23  (FIG. 7). Switch S 1  connects the output of the clock generator  100  to the appropriate LED. In the embodiment, in FIG. 9 to the LED  1   a,  i.e. out on the far left. Switch S 3  connects the amplifier input of the amplifier  5  to the LED  1   b  lying adjacent on the right. Switch S 2  connects the amplifier input of the amplifier  6  to a voltage divider R 1 /R 2 , which is connected to the output of the clock generator  100 . The divider ratio of the voltage divider R 1 /R 2  is so dimensioned that the magnitude of the divided-down transmitted clock signal is slightly greater than the received signal of LED  1   b  produced by parasitic reflection at the translucent surface.  
         [0060]    It is thereby guaranteed that, when the finger is moved over the LED row, e.g. from the middle to the left over LED  1   a,  the latter as the last LED in the row emits light. If, on the other hand, the finger is moved from the side across the light-emitting LED  1   a  towards the middle of the LED row, then in the position of the finger  2  between LED  1   a  and  1   b  the reflection of the transmitting LED  1   a  at the finger will produce a greater signal than was supplied by the voltage divider R 1 /R 2 . The phase angle of the signal S 10  (FIG. 6) is therefore reversed and the selection of LED  1   a  switches over to LED  1   b,  and/or follows the finger  2 .  
         [0061]    With the previously described arrangement for controlling the LED row the light may of course be shifted by the finger only in one direction in each case. The reason for this is that, from a specific distance—determined by the threshold values defined in the window comparator  22  (FIG. 7)—of the finger from the centre of the actually light-emitting LED, the light shifts in front of the moving finger  2 . If by virtue of continuous finger movement the actually light-emitting LED is passed over again, the light switches in front of the finger to the next LED and so on. If, however, after a shift the finger  2  stops and is moved back, the last light-emitting LED remains in its last position. To reverse the direction of motion, the finger then has to be placed—viewed in the direction of motion—in front of the light-emitting LED. It has to be passed over in the, then, reverse direction of motion. The display then follows the finger position once more.  
         [0062]    However, as this is impractical in general use, between the comparator  16  (FIG. 6) and the window comparator  22  (FIG. 7) a circuit is inserted, which ensures that the light spot always directly follows the finger movement. This circuit arrangement utilizes the effect whereby during the changeover from one LED to the next LED the polarity of the counter control signal (output signal S 15 ) and of the analogue output voltage of the comparator  16  (output signal S 17 ) is reversed. This is easy to explain if one considers that the changeover occurs when the finger moves e.g. to the right away from the light-emitting LED and the LED situated on the right of this LED detects an increased reflection. If this value exceeds a predetermined quantity, then the window comparator  22  supplies a corresponding signal and the position counter  23  (FIG. 7) counts one value “upwards”, in this case therefore to the “right”. The originally light-emitting LED “shifts” from the, relative to the finger  2 , left position to the position on the right of the finger. The LED originally connected as a light-emitting element changes its function and becomes the opto-receiver, which is however now situated on the left of the transmitting element. However, as the finger  2  is still situated in an approximately identical position, the LED situated on the left of the transmitting element then receives more reflection than the LED situated on the right of the transmitting element. This however means, across the output of the summing stage  10  (FIG. 6), a reversal of the phase and hence also a reversal of the polarity of the digital output signal S 15  and also of the analogue output signal S 17 .  
         [0063]    [0063]FIG. 10 describes the phases and amplitude relationship of the analogue output signal S 17  (FIG. 6) of the comparator  16  in such a case. Position  51  or LED  1   a  . . .  1   n,  respectively, show the mechanical arrangement of the LEDs,  52  the associated signal values of the analogue output signal S 17  of the comparator  16 .  53  corresponds in the illustrated case to a signal, when LED  1   c  is emitting light. If during a finger movement to the right the output signal S 17  of the comparator  16  falls below the preselected lower threshold value US, the position counter  23  counts one counter upwards ( 54  in FIG. 10). The counter setting determines which LED is selected in switching mode ( 55  FIG. 10). The solid bold line  56  shows the characteristic of the output signal S 17  of the comparator  16  when a finger  2  is moved from left to right over the LED row.  
         [0064]    In the changeover situation, the threshold value OS of the window comparator  22  is again—in a different polarity—exceeded and so the position counter  23  will count back again. A continuous changeover of the LED positions symmetrically relative to the finger  2  would be the result. The light-emitting LEDs follow the finger  2  in that, when the finger is positioned centrally on an LED, only this LED emits light, whereas, when the finger is positioned between two LEDs, both emit light in rapid alternation.  
         [0065]    For tolerances reasons, however, after a first overshooting of the threshold value US a changeover may be effected, after which the threshold value OS is in turn overshot and a second changeover is effected back to the original position, only this time the threshold value US is not undershot so that a further changeover is not absolutely guaranteed. Upon movement of the finger over the LED row the display may consequently “become stuck”.  
         [0066]    [0066]FIG. 11 shows the analogue output signal S 17  (FIG. 6) of the position recognition comparator  16 . In section  61  the finger  2  moves from the centre of the transmitting LED e.g. to the right, the analogue output signal S 17  of the comparator  16  correspondingly increases. When it hits the upper threshold value OS, the LED selection advances to the next LED on the right. The sign of the output signal therefore reverses ( 62 ) and the signal reaches the lower threshold value US. The LED selection switches back to the previous LED. Naturally, there is also a corresponding changeover of the LEDs connected as receivers.  
         [0067]    Undesirable tolerances, e.g. as a result of a scratch on the translucent surface, may lead to the situation where the LED does in fact “shift”, because the upper threshold value OS was reached without difficulty ( 63 , FIG. 11), but afterwards the lower threshold value US after the change of sign is no longer undershot ( 64 , FIG. 11). If the operator in this situation reverses the direction of the finger movement because e.g. the operator wishes to move back from this adjusted value, the display does not respond and, despite movement of the finger, remains in position. This maloperation may easily be prevented in that after each change of LED the output signal S 17  is utilized in its entire magnitude from zero. Previously, it had to run through the voltage range from the upper threshold value OS, through zero to the lower threshold value US. Upon a second switching operation back to the original position there was a factor of uncertainty about reattainment of the lower threshold value US. If, however, the instantaneous output signal S 17  of the comparator  16  is referred to “0” at the changeover moment, the Δ of the signal starts at zero and therefore exceeds the respective threshold value with double amplitude, which guarantees unconditional switching reliability.  
         [0068]    In FIG. 12 a low pass constructed from R 3  and C 3  forms a time delay for the signal S 17  of the comparator  16 . Capacitor C 2  together with switch S 4  forms a referencing unit. Buffer B is used only to electrically isolate the referencing unit C 2 /S 4  from the low pass R 3 /C 3 . D 1  is a differentiating apparatus for a counting signal of the position counter  23 . Each time the numerical value S 23  of the position counter  23  changes, a short pulse is applied via a signal line SD 1  to switch S 4  and, when switch S 4  is closed, the capacitor C 2  is discharged to zero. The output signal S 17  of the comparator  16  because of the delaying low-pass effect of the low pass R 3 /C 3  at the output of the buffer B during the switching time of switch S 4  has experienced only an insubstantial change, so that virtually the entire Δ of the output signal S 17  may come into effect across the input of the window comparator  22 . Naturally, zero is only one example of a preselected or preselectable value. Referencing may be effected also to another specific preselected or preselectable value, so that after the changeover the next threshold value US or OS is reached with part of the output signal S 17 .  
         [0069]    With the circuit according to FIG. 12 it is guaranteed that each finger movement is easily detected and the light-emitting LED always follows the finger movement. In said case, only one LED emits light when the finger is situated centrally on it, and two adjacent LEDs when the finger is situated between them. In the latter case, the position of the light-emitting LED alternates at a frequency determined by the low pass R 3 /C 3 . Given suitable dimensioning, the frequency may be higher than is detectable with the eye, so that a continuous emission of light is perceived. Analogously to the finger position between the two LEDs, there is a corresponding distribution of the intensity of the luminosity. In the embodiment, R 3  has 10 kΩ, R 4  1 MΩ, R 5  10 kΩ, R 6  1 kΩ and R 7  10 kω. C 2  has a value of 0.1 μF and C 3  a value of 10 nF.  
         [0070]    [0070]FIG. 13 shows the analogue output signal S 17  across the output of the buffer B (FIG. 12) when a finger is moved over the LED row without switch S 4  being actuated. FIG. 14 shows the same analogue output signal S 17  only across the input of the window comparator  22 , when the switch S 4  upon each change of position refers the signal S 17  to zero ( 71  in FIG. 14). The dashed lines  72 ,  73  correspond to the signal if no further changeover were to occur. It is clear that the output signal S 17  after referencing  71  would definitely exceed the threshold value OS or US, respectively, and therefore leads to a trouble-free switching operation. The steep flank arises during the referencing  71  when switch S 4  for a short time during the position switching operation discharges the capacitor to “0”. To prevent the input voltage of the window comparator  22  from “drifting away” on account of the open switch S 4 , a high-value resistor R 4  is connected in parallel to the switch S 4 . The d.c. decoupling by means of capacitor C 2  and resistor R 4  additionally also prevents the influence of disturbances, e.g. an asymmetry across the output of the comparator  16  owing to scratches on the translucent surface. The disturbance-induced signal deviation from zero, when the finger has been removed, is automatically referenced to zero after the capacitor C 2 .  
         [0071]    Often, however, given a finger position between  2  adjacent LEDs, for easier selection only one of the two LEDs should emit light. And namely the one that is nearest to the controlling finger. In the previously described embodiment both LEDs emit light alternately, according to the construction so quickly that to the eye it appears like a continuous emission of light. FIG. 15 shows the signal V 1 , which is derived from the output signal S 17 , across the input of the window comparator  22  in FIG. 12 when the finger  2  is situated between two LEDs. AP shows the activation phases of the two LEDs n and n+1.  
         [0072]    In order in this situation to be able to opt for one of the two LEDs, by means of a hysteresis detector  84  (FIG. 16) as a decision aid a control signal S 84  is produced for the two threshold values OS and US. The hysteresis detector  84  checks the count value of the position counter  23  (FIG. 7) for periodic counting operations with maximum counting increments ±1. If such a switching sequence appears in the count value S 23  for a number of periods (e.g. greater than 5) within a predetermined time, the hysteresis detector  84  opens the switch S 5 . This is always the case when a finger is situated between two adjacent LEDs. If switch S 5  opens, the capacitor C 5  charges up from the threshold value preselected by the voltage divider R 5 , R 6 , R 7 , i.e. towards a higher potential. In said case, the upper threshold value rises, while the lower threshold value drops.  
         [0073]    The control device  24  therefore switches back and forth between adjacent light-emitting diodes, if the finger  2  remains between adjacent LEDs without changing, and increases the sensitivity for position recognition until a preselected value is exceeded. Thus, in the event of repeated switching back and forth a decision aid is activated, which sets the receiving element less and less sensitively until the light-emitting diode situated closer to the body may be clearly determined. The decision aid then reverts to the state of sensitivity for the detection of further movement of the finger  2 .  
         [0074]    [0074]FIG. 17 shows the variation of the threshold value OS and US. In the period t 1  the hysteresis detector  84  has identified at least five switching operations between two adjacent LEDs and has set the control signal S 84  to “low” so that the switch S 5  has been opened. This state lasts until the signal V 1  no longer exceeds the threshold values ( 81  FIG. 17) and only one LED emits light. This is registered by the hysteresis detector  84  and it closes switch S 5  again. The time constant of the capacitor C 3  and of the resistor R 5  is to be so dimensioned that it is greater than the time constant of C 2  and R 4  in order to guarantee trouble-free referencing of the signal V 1 . The circuit arrangement has then reattained its original sensitivity for the detection of finger movement. The changeover of the threshold values OS and US may be effected so quickly that a simultaneous emission of light by two LEDs occurs for only such a short time during the finger movement that it is not perceived by the eye.  
         [0075]    For improved comfort a circuit may be additionally inserted, which is not more closely designated here and which in the event of an inadvertent displacement of the finger  2  during removal results in no shift of position of the LEDs and hence of the desired control value. For this purpose, the distance signal S 21  is evaluated. If this indicates a removal of the finger with a simultaneous change of position, then this change of position is accordingly ignored, e.g. by disabling the position counter  23 . Preferably, a value of the deviation from the last signal of e.g. 10% may also be preselected. If this value is exceeded during removal of the body, the control device  24  selects the LED, at which the body last dwelt for longer than a preselected dwell time, e.g. t 28 .  
         [0076]    Despite the seemingly comprehensive signal evaluation, a touch-sensitive LED row in the form of an IC (integrated circuit) with external LEDs is perfectly easy to realize. Such an arrangement may be used for example, directly as a “volume control”, to process a digital data stream or alternatively only to output the “position” (FIG. 18 a, b, c ). Measures may also be taken so that after disconnection of the power supply the actual counter content of the position counter  23  is retained until it is activated again. Unlike mechanical sliding controls (FIG. 19), which generally comprise a straight sliding region from a point A to a point B, the touch-sensitive LED row may be realized in any desired form of presentation, e.g. arc-shaped or round (FIG. 20/FIG. 21). To lengthen the operating path, LED rows may also be cascaded. Accordingly, if the function of a last LED in a row is functionally linked to a first LED of the same row, a virtual turning knob may easily be produced (FIG. 22).  
         [0077]    The regulating/adjusting unit  30  will generally comprise only one display, i.e. only one light-emitting element. Naturally, however, the principle—1 transmitter, 2 receivers grouped at a small or large, uniform or non-uniform distance around the transmitter—may also be transposed. In said case, two transmitters alternately transmit and one receiver disposed midway between the two transmitters evaluates the reflected signal. Such a circuit arrangement, but without the variation of position required for the touch-sensitive LED row, is described in the earlier German patent application 101 33 823.6. By virtue of automatic correction of the received signal to zero, in the above-mentioned circuit arrangement potentially disturbing extraneous light influences are totally avoided.  
         [0078]    In an arrangement with 2 transmitting elements, the finger is positioned in the “gap” between the two transmitting elements and then shifted by moving the finger into the desired position. Naturally, here too, a “momentary contact” with the “gap” may initially activate a further shift facility (FIG. 24).  
         [0079]    [0079]FIG. 25 shows a complete block diagram of the “touch-sensitive LED row”.  
         [0080]    Occasionally, a rapid change of the selected setting of the regulating/adjusting unit may also be desirable. Up until now, what has mostly been mentioned is a momentary contact with the light-emitting LED or the gap. It is however also possible for the entire LED row, after adjustment has been effected, i.e. when, for example, removal of the actuating body has been recognized, to be activated at regular intervals, e.g. at a frequency not visible to the human eye, in order to check whether and where a body is approaching or where there is momentary contact, and there e.g. after momentary contact to take over the LED as a display and also correspondingly activate the regulating/adjusting unit.  
         [0081]    It is self-evident that this description may be subject to a wide range of modifications, alterations and adaptations, which are in the range of equivalents to the appended claims.