Patent Publication Number: US-RE42199-E

Title: Integrated touch sensor and light apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority from U.S. patent application Ser. No.  10 / 271 , 438 , filed on Oct.  15 ,  2002 , which claims priority from U.S. Provisional Patent Applications Ser.  Application No. 60/334,040, filed on Nov. 20, 2001, and U.S. Provisional Patent Application No. 60/341,350, filed on Dec. 18, 2001. The disclosures of the foregoing references are hereby incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     Touch sensors are solid state switches that respond to a user&#39;s touch or encroachment. As such, they often can be used in place of conventional mechanical switches. Known touch sensors typically include a touch pad having one or more electrodes and an associated circuit that induces an electric field about the touch pad and responds to changes in the electric field when the electric field is disturbed by a stimulus such as a user&#39;s touch or proximity. The touch pad and associated circuit typically are disposed on a substrate such as a printed wiring board or a piece of glass. A portion of this or another related substrate typically defines an operative touch surface which the user must touch or approach to provide the stimulus required to trigger the touch sensor. The control circuit can be configured to control a device such as a light, motor or other device. 
     Several types of touch sensors are known in the art, including capacitive touch sensors, infrared touch sensors, electric field touch sensors, acoustic touch sensors and electromagnetic touch sensors. Such touch sensors can be configured as described in U.S. Pat. No. 5,594,222, No. 5,856,646, No. 6,310,611, and No. 6,320,282 and in many other ways. 
     Touch sensors can be used as part of an input/output system where some form of aural or visual feedback is provided. Feedback can involve either alerting the user to the presence of an operative touch surface or informing the user that a touch has triggered a response in the touch sensor. In many cases, visual feedback involves back-lighting the operative touch surface or other areas on an interface panel. Backlighting can be provided by a light emitting diode (LED) or a light emitting polymer (LEP), including an organic light emitting diode (OLED) or a polymer light emitting diode (PLED) (both of which are LEPs), or any other suitable light source. 
     LED, OLED and PLED devices convert electrical energy to light energy in the form of photons. These light emitting devices can include either a transparent anode or a transparent cathode through which the photons generated at their light emitting layers can pass. The light emitting layers of LEDs include semiconductors with doped physical lattice crystal structures. The light emitting layers of OLEDs and PLEDs are composed of small organic molecules and relatively larger organic molecules, respectively. All of the foregoing light emitting devices are typically very thin and can be constructed into point sources or can be made to illuminate large areas, but it may be more economical to do so with OLEDs and PLEDs than with semiconductor devices like LEDs. Using thermal evaporator, thin film sputtering or spin coating techniques, both OLEDs and PLEDs can be mass produced in fewer steps than can semiconductors and may also be economically produced using micro-deposition or ink jet and spin coating equipment. Light produced by any light source can also be spread out or diffused using lenses, light pipes and other suitable devices. 
     Because backlighting can be advantageously aligned with an operative touch surface, it is sometimes desirable to locate a touch sensor in close proximity to and/or atop a light emitting device. In the latter case, the touch sensor&#39;s electrodes preferably are transparent to allow the light produced by the light emitting device to reach the user. In the prior art, these electrodes are separate components of the backlit touch sensor. Because the touch sensor and backlighting device are separate components, the electrical addressing required to drive them both is often complicated and costly. In cases where the touch sensor must overlie the light emitting device, the light from the light emitting device can be attenuated by the transparent layers of an OLED or PLED and further by the touch sensor components before it reaches the user. In all cases, aligning a light emitting device with a separately constructed touch sensor involves extra material and other manufacturing costs owing to the required connections and alignment of the two. 
     SUMMARY OF THE INVENTION 
     The present invention relates to integration of touch sensors with light emitting devices. One embodiment of the invention involves touch sensors having one or more electrodes that also serve as a conducting layer of a light emitting device. Another embodiment of the invention involves various touch sensor configurations wherein a touch sensor physically overlies but is electrically separate from a light emitting device. The invention further relates to electrical drive and control circuits for operating such devices. The various embodiments of the present invention described below can greatly reduce the cost and complexity of using backlighting with touch sensors. For instance, the present invention can reduce or eliminate the extra material and manufacturing cost associated with the separate touch sensor and lighting assemblies known in the art, which must be electrically coupled and aligned. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A-1C  illustrate typical cross-sectional configurations of an LED, OLED and PLED, respectively, each of which can act as a touch sensor when configured according to the present invention; 
         FIGS. 2A-2C  illustrate the separate layers and construction of an OLED or PLED that can act as a touch sensor; 
         FIGS. 3A-3B  illustrate the basic construction of a capacitive touch sensor; 
         FIG. 3C  illustrates a schematic representation of a drive circuit for a two-by-two matrix of touch sensors; 
         FIGS. 4A-4B  illustrate the basic construction of a touch switch assembly including a typical touch switch with an integrated control circuit in close proximity to the touch sensor; 
         FIG. 4C  illustrates a schematic representation of the integrated control circuit of  FIGS. 4A-4B  including the input stage and block diagrams of the processing and latch circuits; 
         FIGS. 5A-5D  illustrate the separate layers and construction of the capacitive touch sensor of  FIGS. 3A-3B  integrated with an OLED or PLED backlighting device; 
         FIG. 5E  illustrates a schematic representation of a drive circuit for separately stimulating a two-by-two matrix of the integrated touch sensors and light emitting devices of  FIGS. 5A-5D ; 
         FIGS. 5F-5G  are timing diagrams for the drive circuit of  FIG. 5E ; 
         FIGS. 6A-6E  illustrate the separate layers and construction of a bottom-emitting integrated light emitting capacitive touch sensor wherein the electrodes of the touch sensor are conducting layers of the light emitting device; 
         FIGS. 7A-7D  illustrate the separate layers and construction of a top-emitting integrated light emitting capacitive touch sensor wherein the electrodes of the touch sensor are conducting layers of the light emitting device; 
         FIG. 8A  illustrates a schematic of a drive circuit for a two-by-two matrix of the integrated light emitting touch sensors of  FIGS. 6A-7D ; 
         FIG. 8B  is a timing diagram for the drive circuit of  FIG. 8A ; 
         FIGS. 9A-9D  illustrate the separate layers and construction of an integrated touch switch assembly including the capacitive touch switch assembly of  FIGS. 4A-4B  integrated with a light emitting device according to the present invention; 
         FIG. 9E  illustrates a schematic representation of a drive circuit for a two-by-two matrix of the integrated touch switch assemblies of  FIGS. 9A-9D ; 
         FIG. 9F  is a timing diagram for the drive circuit of  FIG. 9E ; 
         FIGS. 10A-10E  illustrate the separate layers and construction of a bottom-emitting integrated light emitting touch switch assembly wherein the inner electrode of the touch switch assembly is a conductive layer of the light emitting device; 
         FIGS. 11A-11B  illustrate a schematic representation of control circuits for the integrated touch switch assembly of  FIG. 10A-10E ; 
         FIG. 11A  illustrates the stimulation of the electrode of the touch switch assembly through the relatively large coupling capacitance of the light emitting device; 
         FIG. 11B  illustrates the direct stimulation of the electrode of the touch switch assembly; 
         FIGS. 12A-12E  illustrate the separate layers and construction of a bottom-emitting integrated light emitting touch switch assembly wherein the electrode of the touch switch assembly is a conductive layer of the light emitting device; 
         FIGS. 13A-13D  illustrate the separate layers and construction of a top-emitting integrated light emitting touch switch assembly wherein the electrode of the touch switch assembly is a conductive layer of the light emitting device; 
         FIG. 13E  illustrates a schematic representation of a drive circuit for a two-by-two matrix of the integrated touch switch assemblies with integrated light emitting devices of  FIGS. 10A-13D ; 
         FIG. 13F  is a timing diagram for the drive circuit of  FIG. 13E ; 
         FIGS. 14A-14C  illustrate the separate layers and construction of a bottom-emitting touch switch assembly according to the present invention including a capacitive touch switch assembly of  FIG. 5A-5B  and an integrated light emitting device; 
         FIGS. 15A-15B  illustrate schematic representations of control circuits for the integrated light emitting touch switch assemblies of  FIGS. 12A-13D  wherein the electrode of the touch switch assemblies is a conductive layer of the light emitting devices ( FIG. 15A  illustrates the stimulation of the touch switch assembly electrode through the relatively large coupling capacitance of the light emitting device, and  FIG. 15B  illustrates the direct stimulation of the electrode of the touch switch assembly); 
         FIG. 15C  illustrates a schematic representation of a control circuit for the integrated touch switch assemblies according to the present invention of  FIGS. 14A-14D ; 
         FIG. 15D  illustrates a schematic representation of a control circuit for the integrated touch switch assembly according to the present invention of  FIGS. 9A-9D ; 
         FIGS. 16A-16J  illustrate touch switches where the light emitting device is coupled with the touch detection electrodes but is neither atop nor underneath them; 
         FIGS. 17A-17J  illustrate the configurations of  FIGS. 16A-16J  where the touch switches include an integrated control circuit proximate the touch detection electrodes; 
         FIGS. 18A-18D  illustrate a touch switch where a light emitting device and an aperture in a touch detection electrode are aligned with an aperture in the carrier substrate and a transparent window in a decorative layer; 
         FIG. 19  illustrates an arrangement of four touch switches each coupled to a light emitting device located remote from the touch pads of the touch switches; 
         FIGS. 20A-20B  illustrate a touch switch with an integrated electroluminescent light emitting device; 
         FIG. 21A  illustrates a possible configuration of the input and output lines of a logic circuit for a touch switch and integrated electroluminescent device depicted in  FIGS. 20A-20B ; 
         FIG. 21B  illustrates a timing diagram for the configuration in  FIG. 21A ; 
         FIG. 22A  illustrates a possible configuration of the input and output lines of a logic circuit for a two-by-two matrix of touch switches and integrated electroluminescent devices depicted in  FIGS. 20A-20B ; 
         FIG. 22B  illustrates a timing diagram for the configuration in  FIG. 22A ; and 
         FIG. 23  illustrates a touch switch with a liquid crystal integrated light emitting device. 
     
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     While the drawings generally depict capacitive and electric field touch switches for the purpose of illustration, the principles of the present invention can be seen by those skilled in the art as appropriate for any manner of touch switch device, including, but not limited to, capacitive touch switches, infrared touch switches, electric field touch switches, acoustic touch switches and electromagnetic touch switches. Specific examples include the touch switches described in U.S. Pat. No. 5,594,222, No. 5,856,646, No. 6,310,611 and No. 6,320,282, each naming David W. Caldwell as inventor. The disclosures of the foregoing U.S. Patents are hereby incorporated herein by reference. The disclosures of U.S. patent applications Ser. No. 10/271,933, entitled Intelligent Shelving System, Ser. No. 10/272,219, entitled Molded/Integrated Touch Switch/Control Panel Assembly and Method for Making Same, Ser. No. 10/272,377, entitled Touch Switch with Integral Control Circuit, and Ser. No. 10/272,047, entitled Touch Sensor with Integrated Decoration, all filed on Oct. 15, 2002 and all naming David W. Caldwell as an inventor, are also hereby incorporated herein by reference. 
       FIGS. 1A-1C  illustrate the separate layers that make up typical light emitting devices. The light emitting devices illustrated in  FIGS. 1A-1C  are bottom-emitting light emitting devices, as would be evident to one skilled in the art, but could also represent top-emitting light emitting devices. The separate layers of each light emitting device shown in  FIGS. 1A-1C  can be disposed on substrate  20  using the techniques discussed above or any other suitable techniques known in the art. The separate layers of each light emitting device include anode  21 , emissive stack  22  and cathode  23 . In  FIGS. 1A-1C , anode  21  is typically transparent and can be composed of indium tin oxide or other transparent electrode material. The composition of emissive stack  22  is slightly different for each device. Thus, in  FIG. 1A , emissive junction layer  22  of the LED depicted can be a standard PN junction material, e.g., InGaN, GaP, AllnGaP, or GaAlAs. In  FIG. 1B , emissive stack  22  of the OLED depicted can include hole injection layer  24 , hole transport layer  25 , emitting layer  26 , which can be, for example, CuPc, NPB, and Alq 3 , respectively, and electron transport layer  27 . In  FIG. 1C , emissive stack of the PLED depicted can include a hole transport layer  25  and emissive layer  26 , which can be PEDOT and PPV, respectively. One difference between the composition of emissive stacks  22  of the OLED of FIG.  1 B and of the PLED of  FIG. 1C  is the relatively larger polymer molecules (not shown) in the latter. The configuration of the OLED of  FIG. 1B  provides for an efficient LEP, but other, less efficient, configurations can be used in any of the embodiments of the present invention described below. For instance, LEPs can include as few as one organic layer. The multiple layered configuration of the OLED (or PLED) depicted in  FIG. 1B  can vary depending on the application. Emissive stack  22  of  FIGS. 1B and 1C  can include HTL, ETL, other emissive organic molecules or composite materials. When these light emitting devices are configured according to certain embodiments of the present invention described below, they can exhibit a touch sensor field and can act as a touch switch when coupled to a control circuit. Each of these devices are compatible with the various embodiments described below. Where one device is used to illustrate an particular embodiment, it will be understood that other light emitting devices could be substituted. 
       FIGS. 2A-2C  illustrate the separate layers and basic construction of a typical bottom-emitting PLED or OLED.  FIG. 2A  shows the anode  21 , emissive stack  22  and cathode  23  of a PLED or OLED. Both anode  21  and cathode  23  include a trace,  36  and  37 , respectively, that allows the PLED or OLED to be connected to a voltage source (not shown).  FIG. 2B  shows a bottom view of the assembled PLED or OLED, with anode  21  beneath emissive stack  22 , which is beneath cathode  23 .  FIG. 2C  shows the assembled PLED or OLED borne on substrate  20 . Anode  21  can advantageously be transparent to allow light from emissive stack  22  to reach the surface of substrate  20 . Other configurations of anode  21  can include a fine mesh or other configuration that, while not transparent, allows at least a portion of light from emissive stack  22  to reach the surface of substrate  20 . In any of the configurations described herein, at least a portion of substrate  20  must be transparent or translucent if light is to pass therethrough. 
       FIGS. 3A-3B  illustrate a capacitive touch sensor.  FIG. 3A  shows electrode  31  connected through trace  34  to square wave voltage source V input  (in other embodiments, other voltage sources and waveforms may be used) and electrode  33 , substantially surrounding electrode  31 , connected through trace  35  to resistance R ouput . Voltage source V input  induces an electric field between and about electrode  31  and electrode  33 .  FIG. 3B  shows a cross-sectional view of the capacitive touch sensor of  FIG. 3A  borne on substrate  20 . Surface  19  of substrate  20  prevent a user from directly touching or coming more than a minimum distance near electrodes  31  and  33 . This creates capacitance C inner  and capacitance C outer  between a user&#39;s appendage and electrodes  31  and  33 , respectively, as shown in  FIG. 3A. A  user&#39;s approach toward or touch of surface  19  of substrate  20  can increase the capacitance between electrode  33  and the user&#39;s approaching or touching appendage. The increased capacitance increases the voltage at electrode  33 . This increased voltage can induce a signal in a control circuit (not shown) to effect a response in an end device (not shown). 
     Other touch sensor configurations are also possible. Electrode  33  could receive the signal of voltage source V input  and electrode  31  could send an output signal to a control circuit or a single electrode could both receive an input signal and send an output signal. A third electrode (not shown) can also be included in the touch sensor of  FIGS. 3A-3B , preferably between electrode  31  and electrode  33 . This third electrode could be connected to the signal of square wave voltage source V input . Electrodes  31  and  33  could then both be connected to a differential control circuit, which then could advantageously be configured to differentiate between the voltages induced in electrodes  31  and  33 . For instance, a relatively large voltage induced in electrode  31  can cause the control circuit to generate an output to effect a response in an end device, while a relatively large voltage induced in electrode  33 , or a comparable voltage induced in both electrodes  31  and  33 , can cause the control circuit to generate no output or a different output so as to effect no response in an end device. 
     Touch sensors can be located on an input/output interface panel in a matrix pattern.  FIG. 3C  illustrates schematically a drive circuit capable of selectively activating the touch sensors of  FIGS. 3A-3B  arranged in a two-by-two matrix. Touch sensors TS 1 -TS 4  are shown schematically. Each touch sensor involves a capacitance C 1  between electrode  31  and electrode  33  and a capacitance C LED  between electrode  33  and surface  19  of substrate  20 . When a user of the interface panel of touch sensors touches or approaches the surface  19  of substrate  20 , the capacitance between electrode  33  and surface  19  and the voltage of electrode  33  can increase. The touch induced voltage increase of electrode  33  prolongs the peak detected by AND gate AND as shown relative to input OSC in FIG.  3 C. The change in voltage can be sent to an output gate, a control circuit or, ultimately, to an end device. 
     The logic gates of the drive circuit of  FIG. 3C  can control the activation of the touch sensors of the matrix. In  FIG. 3C , oscillating signal OSC sends a square wave signal to AND gates AND 1  and AND 2 , which also receive inputs from signals TSCSELECT 1  and TSCSELECT 2 , provided by a logic circuit (not shown). When both oscillating signal OSC and signal TSCSELECT 1  are high, AND gate AND 1  will have a high output TSC 1 , which will induce an electric field in touch sensors TS 1  and TS 2 . Signal TSCSELECT 1  thus works to control the passage of oscillating signal OSC to the touch sensors of the right hand column of touch sensors, composed of touch sensors TS 1  and TS 2 . The analog multiplexer AMP of  FIG. 3C  can select which of the touch sensors TS 1  and TS 2  will be allowed to send a response signal to AND gate AND. When TSELECT 1 , according to a logic circuit (not shown), sends a signal to switch SW 1  that closes it, and TSELECT 2  does not send a similar signal to switch SW 2 , AND gate AND can output a signal on trace AND_OUT that is dependent on the voltage of TS 1 . When either TSELECT 1  or TSELECT 2  send a signal to switch SW 1  or SW 2 , respectively, closing either switches, AND gate AND can output a signal on trace AND_OUT that is dependent on the voltage of either touch sensor TS 1  or TS 2 . Thus, the drive circuit of  FIG. 3C  is capable of activating an individual touch sensor within the matrix, a column of touch sensors within the matrix or a row of touch sensors within the matrix, preferably according to a logic circuit (not shown). 
       FIGS. 4A-4B  illustrate a touch switch with integrated control circuit, wherein integrated control circuit  32  is located proximate touch sensor electrodes  31  and  33 , which are connected to integrated control circuit  32  through traces  34  and  35 , respectively. In  FIG. 4B , the touch switch with integrated control circuit of  FIG. 4A  is shown, in cross-section, borne on substrate  20 .  FIG. 4C  illustrates a possible configuration of integrated control circuit  32  of  FIGS. 4A-4B . In  FIG. 4C , oscillating signal OSC stimulates both electrode  31  and  33  through resistances R inner  and R outer , respectively. Active devices M 2  and M 4  are connected to chip select signal VDD. Though NMOS active devices are shown, other devices could be substituted, including PMOS or bipolar active devices or resistors. The gates of active devices M 1  and M 3  are connected to electrodes  31  and  33 , respectively. Though NMOS devices are shown, other types of active devices could be substituted including PMOS or bipolar active devices. The components of integrated control circuit  32  and electrodes  31  and  33  can be configured so that peak potentials developed at inputs POS and NEG can be substantially equal when no stimulus is applied to either electrode. Alternatively, the neutral state peak potential at input NEG can be relatively higher than at input POS to prevent unintended actuations of the processing and latch circuits  40  and  41 , respectively. When a user-induced stimulus is applied at electrode  31 , electric field capacitance C 1  increases and the potential at electrode  31  increases. The potential at the gate of active device M 1  will then temporarily be greater than the potential at its source, causing active device M 1  to be biased on. When biased on, active device M 1  will have a drain current that can be converted to a proportional potential by active device M 2 , causing the differential between the potential at inputs POS and NEG to change, in turn causing processor circuit  40  to close latch circuit  41  allowing current to develop across resistor R output . The operation of one embodiment of processing circuit  40  and latch circuit  41  is more thoroughly described in U.S. Pat. No. 6,320,282. Other processing outputs and latch circuits could be used as well. 
       FIGS. 5A-5D  illustrate a light emitting touch switch according to the present invention including the capacitive touch sensor of  FIGS. 3A-3B  and the light emitting device of  FIGS. 2A-2C . The embodiment of the present invention depicted in  FIGS. 5A-5D  involves a touch switch and a light emitting device that are physically integrated but electrically separate.  FIG. 5A  shows the separate layers of the light emitting device, including anode  21 , trace  36  connected to anode  21 , emissive stack  22 , cathode  23  and trace  37  connected to cathode  23 .  FIG. 5C  shows the touch sensor including electrode  31 , trace  34  connected to electrode  31 , electrode  33 , and trace  35  connected to electrode  33 . Traces  34  and  35  could function as an output line, could be connected to a signal source or both.  FIG. 5B  shows the separate layers of the light emitting touch switch according to the present invention one atop the other, with the touch switch components of  FIG. 5C , namely, electrodes  31  and  33  atop anode  21  atop emissive stack  22  atop cathode  23 . In  FIG. 5B , electrode  31  is aligned with and overlies anode  21 , which is consequently not labeled.  FIG. 5D  shows the light emitting touch switch according to the present invention borne on substrate  20 . Insulating layer  50  separates the touch sensor components of  FIG. 5C  from the light emitting device components of FIG.  5 A. Insulating layer  50  can be SiO 2  or any other suitable material and is preferably entirely transparent or transparent in certain areas, but may also be non-transparent. Anode  21  of the light emitting device is preferably transparent to allow light from emissive stack  22  to reach surface  19  of substrate  20 , but can be otherwise, as discussed above. As indicated previously, at least a portion of substrate  20  must be transparent or translucent to allow light to pass therethrough to surface  19  thereof. 
       FIG. 5E  illustrates a possible drive circuit capable of controlling the activation of a two-by-two matrix of the physically integrated but electrically separate touch sensors and light emitting devices of  FIGS. 5A-5B . In  FIG. 5E , the activation of individual touch sensors TS 1 -TS 4  or columns of touch sensors is as discussed with reference to  FIG. 3C , except that either electrode  31  or  33  of each of touch sensors TS 1 -TS 4  could be directly connected to input signals TSCSELECT 1  or TSCSELECT 2  and the other electrode  31  or  33  of each of touch sensors TS 1 -TS 4  could be connected to AND gate AND through corresponding switch SW 1  or SW 2  of analog multiplexer AMP. The activation of light emitting devices L 1 -L 4  can be independent of the activation of touch sensors TS 1 -TS 4  or else can be synchronized, or dependent on the activation of touch sensors TS 1 -TS 4 . For instance, a logic circuit (not shown) could activate the light emitting device or devices underneath an activated (i.e., ready for use) individual touch sensor or group of touch sensors. Alternatively, a logic circuit (not shown) could activate the light emitting device or devices underneath an activated and touch stimulated touch sensor or group of touch sensors. Other logic schemes also are possible. The activation of light emitting devices L 1 -L 4  can be controlled by input signals LCSELECT 1  and LCSELECT 2  and LRSELECT 1  and LRSELECT 2  through AND gates AND 3  and AND 4 . For instance, light emitting device L 1  will be on, emitting light, when the output LRS 1  of AND gate AND 3  is high and input LCSELECT 1  is low. In this state, current will flow through light emitting device L 1 , causing it to emit light. The drive circuit of  FIG. 5E  will be understood to be capable of activating either individual light emitting devices or columns or rows of light emitting devices. 
       FIGS. 5F-5G  are timing diagrams of the drive circuit of  FIG. 5E , wherein the timing of the activation of both the touch sensor and light emitting devices are shown. In  FIG. 5F , the timing of the drive circuit is as described above with respect to FIG.  3 C.  FIG. 5F  further shows how output AND_OUT of AND gate AND responds to a user&#39;s touch. For instance, at times T 1  and T 5 , touch sensor TS 1  is activated and the input  61  of AND gate AND can correspond to the potential at either electrode  31  or  33  of touch sensor TS 1 . When touch stimulated, output AND_OUT is high for a shorter interval during time T 1  than when not stimulated. The activation and stimulation of touch sensors T 3 -T 4  is similar to that of touch sensor T 1 . Also, though not shown in  FIG. 5F , a row or column of touch sensors can be activated simultaneously, just as can an individual touch sensor, as can be understood from the description of the drive circuit of FIG.  5 E. 
     In  FIG. 5G , when inputs LRSELECT 1  and OSC are high, the output LRS 1  of AND gate AND 3  will be high. When input LCSELECT 1  is low, output LCS 1  of buffer B 3  will be low. Thus, when inputs LRSELECT 1  and LCSELECT 1  are high, LRS 1  will be high and LCS 1  will be low, causing current to flow through light emitting device L 1 , which will be on and emit light, as shown at times T 1  and T 3  of FIG.  5 F. The drive circuit of  FIG. 5E  is also capable of activating a column or row of light emitting devices. Thus, at times T 2  and T 4 , inputs LRSELECT 1 , LRSELECT 2  and OSC are high, making outputs LRS 1  and LRS 2  high as well, and input LCSELECT 2  is high, making output LCS 2  of buffer B 4  low. The condition of the drive circuit at times T 2  and T 4  will cause current to flow through light emitting devices L 3  and L 4 , causing them to emit light. Activation of a row of light emitting devices is not shown in  FIG. 5G  but will be understood from the description of the drive circuit of FIG.  5 E. 
       FIGS. 6A-7D  illustrate an integrated light emitting touch sensor wherein the conductive layers of the light emitting device, namely anode  121  and cathode  123 , also function as electrodes of the touch sensor.  FIGS. 6A-6E  illustrate a bottom-emitting integrated light emitting touch sensor.  FIGS. 7A-7D  illustrate a top-emitting integrated light emitting touch sensor.  FIGS. 6A and 7A  show the separate layers of the integrated light emitting touch sensor, including anode  121 , emissive stack  22  and cathode  123 . Traces  36  and  37  are connected to anode  121  and cathode  123 , respectively.  FIGS. 6B and 7B  show how voltage source stimulus V input  can be connected through trace  37  to cathode  123  and how trace  36  can be a return line including resistor R output . The layers of the integrated light emitting touch sensor are shown so that, in  FIGS. 6B and 6C , anode  121  overlies emissive stack  22 , which overlies cathode  123 , whereas, in  FIGS. 7B and 7C , cathode  123  overlies emissive stack  22 , which overlies anode  121 .  FIGS. 6C and 7C  show how the integrated light emitting touch sensors of  FIGS. 6B and 7B , respectively, can be borne on substrate  20 . 
     In  FIG. 7C , decorative layer  51  overlies the integrated light emitting touch sensor of FIG.  7 B. As shown in  FIG. 7D , decorative layer  51  can provide the capacitance C 1  between anode  21  and surface  18  of decorative layer  51 , that might otherwise be provided by substrate  20 , as shown in FIG.  6 E. The capacitance C 1  of  FIG. 7D  could also be provided by a second substrate (not shown) overlying the integrated light emitting touch sensor. In both  FIGS. 6E and 7D , capacitance C LED  exists between anode  121  and cathode  123 .  FIG. 6D  shows a schematic representation of the integrated light emitting touch sensors of FIG.  6 B. 
       FIG. 8A  illustrates a possible drive circuit for the integrated light emitting touch sensors of  FIGS. 6A-7D .  FIG. 8B  is a timing diagram for the drive circuit of FIG.  8 A. The drive circuit of  FIG. 8A  advantageously requires only four address lines to control the touch sensor and light activation and operation of the entire matrix. Minimizing the number of address lines conserves space on the substrate that bears the integrated light emitting touch sensors and also reduces the complexity of the manufacturing process. The touch sensor function of integrated light emitting touch sensors TL 1  and TL 2  is activated when output CS 1  of AND gate AND 5  is high, which occurs when the inputs of AND gate AND 5 , namely, oscillating signal OSC and CSELECT 1 , are both high. The analog multiplexer AMP, including switches SW 1  and SW 2 , controls whether the potential at one or the other or both of integrated light emitting touch sensors TL 1  and TL 2  become input  61  of AND gate AND, the output AND_OUT of which forms the touch sensor response output of the matrix of integrated light emitting touch sensors. Inputs LSELECT 1  and LSELECT 2  control active devices M 5  and M 6 , which in turn control the light producing current through the integrated light emitting touch sensors, such that, for example, when LSELECT 1  is low, active device M 5  is biased on and RS 1  is high. Capacitance C isolate  can isolate AND gate AND from the effects of the light emitting operation of the drive circuit. As discussed above, although active devices M 5  and M 6  are shown as PMOS devices, NMOS, bipolar or other active devices can also be used. 
     According to FIG.  8 A and the timing chart of  FIG. 8B , at time T 1 , inputs oscillating signal OSC and CSELECT 1  are both high causing output CS 1  of AND gate AND 5  to be high. Also at time T 1 , inputs LSELECT 1  and LSELECT 2  are both high, causing active devices M 5  and M 6  to be in high impedance mode, thus activating the integrated light emitting touch sensors TL 1  and TL 2 . When input TRSELECT 1  is high, switch SW 1  will close and allow the signal from anode  121  of integrated light emitting touch sensor TL 1  to reach AND gate AND, whose output AND_OUT is the response output of the drive circuit. Similar requirements exist for the activation of other individual integrated light emitting touch sensors or rows or columns thereof. As shown in  FIG. 8B , when there is a touch stimulus to integrated light emitting touch sensor TL 1 , response output AND_OUT will persist for a relatively smaller portion of time T 1  than when there is no stimulus. Stimulation of the other integrated light emitting touch sensors produces a similar response at response output AND_OUT. To activate the light emitting properties of integrated light emitting touch sensor TL 1 , output CS 1  of AND gate AND 5  must be low and input RS 1  must be high. Under these conditions, current can flow from the anode to the cathode of the integrated light emitting touch sensors, causing them to emit light. As can be understood from  FIG. 8B , active device M 5  will be biased when its gate potential is lower than its source, as will occur when input LSELECT 1  is low. When biased on, active device M 5  will allow current to flow from anode  121  to cathode  123  of integrated light emitting touch sensor TL 1 . Integrated light emitting touch sensors TL 2 -TL 4  operate in a similar manner. As can be understood from the drive circuit of FIG.  8 A and the timing diagram of  FIG. 8B , rows and columns of integrated light emitting touch sensors can be lit simultaneously as well. The timing diagram of  FIG. 8B  shows how the light emitting properties of the integrated light emitting touch sensors is synchronized. As discussed above, inputs CSELECT 1 , CSELECT 2 , TRSELECT 1 , TRSELECT 2 , LSELECT 1  and LSELECT 2  can be controlled by a logic circuit (not shown) to make the two modes of the system dependent on one another in any manner required for the particular application. 
       FIGS. 9A-9D  illustrate the separate layers and construction of a touch switch with an integrated control circuit according to  FIGS. 4A-4B  physically integrated with, but electrically separate from, a bottom-emitting light emitting device.  FIG. 9A  shows the separate layers of the light emitting device, including anode  21 , emissive stack  22  and cathode  23 . Traces  36  and  37  connect to anode  21  and cathode  23 , respectively. Anode  21  is preferably transparent to allow light from emissive stack  22  to reach surface  19  of substrate  20 , but can be otherwise, as discussed above.  FIG. 9C  shows the touch switch with integrated control circuit of  FIGS. 4A-4B , including electrode  31 , integrated control circuit  32 , electrode  33 , trace  34  connecting electrode  31  to integrated control circuit  32  and trace  35  connecting electrode  33  to integrated control circuit  32 .  FIGS. 9B and 9D  show how the separate layers of  FIGS. 9A and 9C  are integrated.  FIG. 9D  shows how the integrated assembly of  FIG. 9B  can be borne on substrate  20 . Insulating layer  50  separates the touch sensor components of the touch switch assembly of  FIG. 9C  from the light emitting device and could also serve a decorative function. At least a portion of insulating layer  50  and substrate  20  should be transparent or translucent in order to allow light to pass therethrough from the light emitting device to surface  19 . 
       FIG. 9E  shows a possible drive circuit for the touch switch with integrated control circuit and integrated light emitting device of  FIGS. 9A-9D  arranged in a two-by-two matrix. As will be understood from FIG.  9 E and from the preceding discussion, inputs of the drive circuit can be controlled by a logic circuit (not shown) to make the activation and operation of the touch switches and light emitting devices of the matrix behave dependently. The drive circuit of  FIG. 9E  includes buffers B 2 -B 7  connected to inputs TRSELECT 1 , TRSELECT 2 , LRSELECT 1 , LRSELECT 2  and outputs TCRETURN 1  and TCRETURN 2 , respectively, and active devices M 7  and M 8 , the gates of which are connected to LCSELECT  1  and LCSELECT  2 , respectively. Inputs TRSELECT 1  and TRSELECT 2  control the activation of touch switch with integrated control circuit assemblies TSA 1 -TSA 4 . Outputs TCRETURN 1  and TCRETURN 2  respond to changes induced in the touch sensors of the touch switch with integrated control circuit assemblies TSA 1 -TSA 4 . 
     As shown in the timing diagram of  FIG. 9F , touch switch with integrated control circuit assemblies TSA 1  and TSA 3  are activated, receiving signals and can respond to stimuli to the electric fields about their electrodes when TRS 1  of buffer B 2  is high, activating the integrated control circuits  32  and touch sensors of touch switch with integrated control circuit assemblies TSA 1  and TSA 3 . The output of the integrated control circuits  32  of the touch switch with integrated control circuit assemblies can involve a low voltage when the respective touch switches are not stimulated and a high voltage when they are. Outputs TCR 1  and TCR 2  can develop a current across resistors R output1  and R output2  that can be sent through buffers B 6  and B 7  to outputs TCRETURN 1  and TCRETURN 2  and ultimately to an end device. 
     Light emitting devices L 1 -L 4  receive inputs LRS 1 , LRS 2 , from buffers B 4  and B 5 , respectively, and inputs LCS 1  and LCS 2  from active devices M 7  and M 8 . Light emitting device L 1  will turn on and emit light at time T 1  when, as shown in  FIG. 9F , output LRS 1  of buffer B 4  is high, i.e., when input LCSELECT is high, and input LCS 1  is low. In this condition, active device M 7  will be biased on and provide a current path from anode  21  to cathode  23  of light emitting device L 1 . It will be understood, as discussed above and from  FIGS. 9E and 9F , how other light emitting devices or rows or columns of light emitting devices can be similarly activated. Though the activation and operation of the touch switch with integrated control circuit and light emitting device assemblies is shown as being synchronized in  FIG. 9F , other methods of activating and operating the assemblies and devices are possible. 
       FIGS. 10A-10E  illustrate the separate layers and construction of a bottom-emitting integrated light emitting touch switch with integrated control circuit assembly wherein the inner electrode  121  of the touch switch with integrated control circuit assembly is a conductive layer of the light emitting device.  FIG. 10A  shows the separate layers of the integrated light emitting touch switch with integrated control circuit, including anode  121 , emissive stack  22  and cathode  23 .  FIG. 10C  shows the touch switch with integrated control circuit assembly, including anode  121 , electrode  33  and integrated control circuit  32 .  FIG. 10B  shows the layers assembled into an integrated light emitting touch switch with integrated control circuit assembly. In  FIG. 10B , traces  36 ,  37  and  35  connect anode  121 , cathode  23  and electrode  33 , respectively, to integrated control circuit  32 .  FIG. 10D  shows a cross-section view of how the integrated light emitting touch switch with integrated control circuit assembly can be borne on substrate  20 . In  FIG. 10D , anode  121  overlies emissive stack  22 , which in turn overlies cathode  23 . Electrode  33  is borne on substrate  20  substantially surrounding the integrated light emitting touch switch with integrated control circuit assembly.  FIG. 10E  shows a schematic representation of capacitance C 1  at surface  19  of substrate  20  and capacitance C LED  between anode  121  and cathode  23 . Integrated control circuit  32  of  FIG. 10B  can control the activation and operation of the touch switch and light emitting layers  22  of the integrated light emitting touch switch assembly. The integrated light emitting touch switch assembly of  FIG. 10B  can form a low impedance touch sensing device. Anode  121  is preferably, though not necessarily, transparent. The integrated light emitting touch switch with integrated control circuit assembly of  FIGS. 10A-10E  can be controlled by the control circuit depicted in  FIGS. 11A-11B . 
       FIGS. 11A-11B  show schematic representations of control circuits capable of controlling the integrated light emitting touch switch with integrated control circuit assemblies of FIG.  10 . In  FIGS. 11A-11B , integrated control circuit  32  produces a differential response output through logic and decision circuit  40  and latch circuit  41 . In  FIG. 11A , oscillating signal OSC from logic and decision circuit  40  activates electrodes  121  and  33  through the buffering configuration of active devices M 14  and M 15  and through electrodes R inner  and R outer , respectively. Anode  121  is activated by oscillating signal OSC through the relatively large coupling capacitance of light emitting device LED. Active device M 13  is shown connected to logic and decision circuit  40 , to anode  121  of light emitting device LED through resistance R LED1  and to chip select signal VDD. Active device M 12  is shown connected to cathode  23  of light emitting device LED through resistance R LED2 , diode D 1  and active device M 14 . During the touch sensing operation of the control circuit, active devices M 13  and M 12  are unbiased and in a non-conducting high impedance state and the operation of the control circuit is similar to the operation of the control circuits described with reference to FIG.  4 C and in U.S. Pat. No. 6,320,282. During the LED drive operation of the control circuit, active devices M 14 , M 13  and M 12  will be biased on, conducting and low impedance, and chip select signal VDD will be applied to the source of active device M 13 , allowing current to flow with low impedance through resistance R LED1 , anode and cathode  21  and  23  of light emitting device LED and resistances R inner  and R LED2 . The current flowing through light emitting device LED will cause it to emit light. 
       FIG. 11B  shows how oscillating signal OSC can drive anode  121  directly, instead of through the relatively large coupling capacitance of light emitting device LED. The control circuit of  FIG. 11B  includes active device M 13 , connected to logic and decision circuit  40 , chip select signal VDD and anode  121  and active device M 20 , connected to logic and decision circuit  40  and to cathode  23  of light emitting device LED through resistance R LED1 . Also, capacitance C block  can isolate the touch sensing circuit from DC current through light emitting device LED during LED drive operation of the drive circuit. Optional active device M 21  can provide an AC ground for the touch sensor. The control circuit of  FIG. 11B  works as does the drive circuit of  FIG. 11A  during touch sensing operation. During LED drive operation, active devices M 20 , M 13  and M 12  will be biased on, conducting and low impedance, and chip select signal VDD will be applied, allowing current to flow through light emitting device LED and resistances R LED1  and R LED2 . In both  FIGS. 11A and 11B , current can be limited by altering the values of the various resistances and characteristics of the active devices. Although PMOS or NMOS devices have been shown in certain locations within the control circuit, it will be understood that other devices, including bipolar devices, could be used as well.  FIG. 13F  illustrates a timing diagram that can correspond to the operation of a matrix of touch sensors with integrated control circuits  32  like the one depicted in  FIGS. 11A  or  11 B. 
       FIGS. 12A-12E  illustrate the separate layers and construction of a bottom-emitting integrated light emitting touch switch with integrated control circuit assembly wherein the single electrode  121  of the touch switch assembly is a conductive layer of the light emitting device.  FIG. 12A  shows the separate layers of the integrated light emitting touch sensor, including anode  121 , emissive stack  22  and cathode  123 . Trace  37  can connect cathode  123  to integrated control circuit  32 , as shown in FIG.  12 B.  FIG. 12C  shows the touch sensor including anode  121  and trace  36  connecting anode  121  to integrated control circuit  32  in single electrode mode.  FIG. 12B  shows how the separate layers can be assembled to form an integrated light emitting touch switch with integrated control circuit assembly.  FIG. 12D  shows a cross-section view of how the assembly of  FIG. 12B  can be borne on substrate  20 . In  FIG. 12D , anode  121  overlies emissive stack  22 , which overlies cathode  123 .  FIG. 12E  shows a schematic representation of capacitance C 1  between surface  19  of substrate  20  and capacitance C LED  between anode  121  and cathode  123 . Integrated control circuit  32  of  FIG. 10B  can control the activation and operation of the touch switch and light emitting layers of the integrated light emitting touch switch assembly. The integrated light emitting touch switch assembly of  FIG. 10B  can form a low impedance touch sensing device. Anode  121  is preferably, though not necessarily, transparent. Also, at least a portion of substrate  20  should be transparent or translucent to allow light to pass therethrough from the light emitting device to surface  19 . 
       FIGS. 13A-13D  illustrate the separate layers and construction of a top-emitting integrated light emitting touch switch with integrated control circuit assembly wherein the single electrode  121  of the touch switch assembly is a conductive layer of the light emitting device.  FIGS. 13A-13D  are as described with reference to  FIGS. 12A-12D , except that anode  121 , emissive stack  22  and cathode  123  of the  FIGS. 13A-13D  embodiment are borne on surface  19  of substrate  20  and covered by decorative layer  59 , while integrated control circuit  32  is borne on the other side of substrate  20 , opposite surface  19 , and connected to anode  121  and cathode  123  through substrate  20  via traces  36  and  37 , respectively. To accommodate traces  36  and  37 , substrate  20  can, but need not, include cutout sections or can be formed around the traces during manufacture of the touch switch with integrated control circuit assembly. Traces  36  and  37  also could be connected to integrated control circuit  32  using separate traces built into substrate  20 . As discussed above, decorative layer  59  could be replaced by a second substrate (not shown) and can include transparent areas to allow light from emissive stack  22  to reach the user of the integrated light emitting touch switch with integrated control circuit assembly. 
     The activation and operation of a two-by-two matrix of the integrated light emitting touch switch with integrated control circuit assemblies of  FIGS. 12A-13D  can be controlled by the drive circuit of  FIG. 13E  according to the timing diagram of FIG.  13 F. Other drive circuits and timing schemes also can be used. The drive circuit of  FIG. 13E  advantageously requires only four address lines, which, as discussed above with respect to  FIG. 8A , conserves space and reduces the complexity of the touch switch matrix configuration and its manufacture. The drive circuit of  FIG. 13E  includes inputs CS 1  and CS 2 , which control the touch switch activation of columns of integrated light emitting touch switch with integrated control circuit assemblies within the matrix, and inputs LEDSEL 1  and LEDSEL 2 , which control the light activation of rows of integrated light emitting touch switch assemblies. Returns RS 1  and RS 2  are touch switch response outputs of the integrated control circuits  32  of the two rows of integrated light emitting touch switch assemblies. Buffers B 9 -B 10  buffer the input signals and buffers B 11 -B 12  buffer the response output signals. Active devices M 10  and M 11  can be biased on by inputs LEDSEL 1  and LEDSEL 2  to allow current to flow from the anode through the emissive layers and to the cathode of the integrated light emitting touch switch with integrated control circuit assemblies TL 1 -TL 4  to produce light. The signals of the timing diagram of  FIG. 13F  are shown synchronized, but as discussed above, could be otherwise. At time T 1 , the touch sensor function of integrated light emitting touch switch assemblies TL 1  and TL 2  is activated because input CS 1  is high. The touch sensor function of integrated light emitting touch switch with integrated control circuit assemblies TL 3  and TL 4  is not activated because input CS 2  is low. Thus, at time T 1 , either one or both of integrated light emitting touch switch with integrated control circuit assemblies TL 1  and TL 2  could relay a touch stimulated signal to response output RS 1  or RS 2 , respectively. 
     At time T 5 , integrated light emitting touch switch with integrated control circuit assembly TL 1  emits light and its touch sensor function is activated because input CS 1  is high at times T 4  and T 5 . Also, input LEDSEL 1  is high and consequently active device M 10  is biased on, allowing current to flow through it. 
     The touch sensor and light activation of the other integrated light emitting touch switch with integrated control circuit assemblies is similar to the activation of integrated light emitting touch switch with integrated control circuit assembly TL 1 . It will be understood for  FIGS. 13E and 13F  that rows and columns of integrated light emitting touch switch with integrated control circuit assemblies can also act as touch switches and emit light as well. The touch sensor operation and light emission of the integrated light emitting touch switch with integrated control circuit assemblies of  FIG. 13E  are therefore shown synchronized such that an integrated light emitting touch switch with integrated control circuit assembly will emit light only when touch stimulated. Other patterns of activation could also be advantageous as discussed above. 
       FIGS. 14A-14C  illustrate the separate layers and construction of a bottom-emitting touch switch with integrated control circuit assembly according to the present invention including a touch switch with integrated control circuit assembly of  FIG. 5A-5B  and an integrated light emitting device.  FIG. 14A  shows the separate layers of the light emitting device and the touch sensor, including anode  21 , emissive stack  22 , cathode  23  and electrode  31 .  FIG. 14B  shows how the separate layers can be assembled and connected through traces  34 ,  36  and  37  to integrated control circuit  32 .  FIG. 14C  shows a cross-section view of how the assembly of  FIG. 14B  can be borne on substrate  20 . In  FIGS. 14B and 14C , electrode  33  is shown overlying anode  21 , which in turn overlies emissive stack  22  and cathode  23 . Insulating layer  50  separates electrode  31  from the layers of the light emitting device. Insulating layer  51  is preferably transparent and can be SiO 2  or any other suitable dielectric material. Electrode  31  and anode  21  are also preferably transparent but, as described above, need not be. As shown in  FIGS. 14A-14C , electrode  31  and anode  21  could be smaller than emissive stack  22 , allowing the light emitting device to form a border or halo around even a non-transparent electrode  31  or anode  21 . Thus, in certain applications, a transparent electrode and anode need not be used. A possible control circuit for the integrated light emitting touch switch assembly of  FIG. 14C  is described with reference to  FIGS. 15C-15D . 
       FIGS. 15A-15B  show schematic representations of possible control circuits capable of controlling the integrated light emitting touch switch with integrated control circuit assemblies of  FIGS. 12D and 13D , involving anode  121 . Anode  121  in  FIGS. 15A-15B  is connected to integrated control circuit  32  as described with reference to  FIGS. 11A-11B . Here, resistance R inner  has been renamed R touch , because the integrated light emitting touch switch with integrated control circuit assemblies of  FIGS. 12D and 13D  do not include inner and outer electrodes. During the touch sensing operation of the control circuit, active devices M 12  and M 13  will be unbiased, nonconducting and high impedance, and the control circuit will operate in a manner similar to the manner described with reference to  FIGS. 11A-11D , except that logic and decision circuit  40  will have only one input and therefore will not provide a differential output to latch circuit  41 .  FIG. 15B  shows a control circuit capable of activating anode  121  directly and not through the relatively large coupling capacitance of light emitting device LED. During LED drive operation, the control circuit of  FIG. 15B  operates as described with reference to FIG.  11 B. 
       FIG. 15C  illustrates a schematic representation of a possible control circuit capable of controlling the integrated light emitting touch switch with integrated control circuit assembly of FIG.  14 C. During touch sensing operation, the control circuit of  FIG. 15C  works as described above with reference to FIG.  15 B. Also, during touch sensing operation there is no DC path for current flow through light emitting device LED, other than leakage current, for this control circuit. During light emitting device LED drive operation, capacitance C 3  between electrode  31  and anode  21  isolates the touch switch operation circuitry from the current of the LED drive operation of the circuit. As shown in  FIG. 14C , capacitance C 3 , represented schematically in  FIG. 15C , is provided by isolating layer  50 , which may be any suitable material including SiO 2 . 
       FIG. 15D  illustrates a schematic representation of a possible control circuit capable of controlling the integrated light emitting touch switch assembly shown generally in  FIG. 14C , but further including an outer electrode  33 . The control circuit in  FIG. 15D  works as described above with reference to  FIG. 15C , except that electrode  33 , active devices M 18  and M 19  and resistance R outer  provide input to logic and decision circuit  40 , which can be capable of providing a differential output to latch circuit  40 . 
       FIG. 16A  shows the electrodes  31  and  32  and traces  34  and  35  of a touch pad.  FIGS. 16B-16J  show light emitting devices LEDV, which can be, for example, inorganic semiconducting diodes, having anode  21 , emissive junction  22  and cathode  23  coupled to electrodes  31  and  33  of the touch pad of  FIG. 16A  at anode  21  and cathode  23 , respectively. The configurations depicted in  FIGS. 16B-16J  show how inorganic semiconducting diodes and other light emitting devices can, according to the present invention, be located in various locations relative to the touch pad with which they are coupled, including remote from the electrodes of the touch pad. Such configurations can provide flexibility in the design of integrated light emitting touch sensor devices and can at the same time offer simple addressing schemes, as shown in  FIG. 19 , described below. In  FIG. 16B , light emitting device LEDV is oriented between electrodes  31  and  33  so that light can reach surface  19  of substrate  20  without having to pass through either electrode  31  or  33 . Thus, electrodes  31  and  33  need not be transparent to allow light to reach surface  19  of substrate  20 , shown in FIG.  16 B. To allow light from light emitting device LEDV to reach surface  19 , substrate  20  is preferably transparent.  FIGS. 16C-16J , like  FIG. 16B , each illustrate touch switches where a light emitting device is coupled with the touch detection electrodes  31  and  33  but is neither atop nor underneath them, allowing light emitted from light emitting device LEDV to reach surface  19  and obviating the need for transparent electrodes. 
     In  FIGS. 16C and 16D , emissive stack  22  of light emitting device LEDV is located between electrode  31  and electrode  33 . Anode  21  and cathode  23  are coupled to electrode  31  and electrode  33  in  FIG. 16C , and vice versa in FIG.  16 D. Anode  21  and cathode  23  could also be directly composed of electrode  31  or electrode  33 , eliminating the need from small circuit traces or integration of the electrodes. In  FIGS. 16E and 16F , light emitting device LEDV is located remote from electrodes  31  and  33  and anode  21  and cathode  23  are coupled to electrodes  31  or  33  through traces  34  and  35 . Electrodes  31  and  33  could be coupled to a control circuit (not shown) either through traces  34  and  35  as well or through other, separate traces (not shown). In  FIGS. 16G and 16H , each touch switch has four light emitting devices LEDV located between electrode  31  and electrode  33 . In  FIG. 16G , traces  58  connect anode to electrode  31 , where in  FIG. 16H , traces  58  connect cathode  23  to electrode  31 . In  FIG. 16I and 16J , electrode  31  has a notch  52  that accommodates light emitting device LEDV. In  FIG. 16I , anode  21  is coupled to electrode  31  and cathode  23  is coupled to electrode  33  through trace  57 , where in  FIG. 16J , cathode  23  is coupled to electrode  31  and anode  21  is coupled to electrode  33  through trace  57 . In both  FIGS. 16I and 16J , notch  52 , and consequently light emitting device LEDV, is shown located in the center of electrode  31 . Other such configurations and variations on the configurations shown in these drawings are possible as well. 
     In addition to obviating the need for transparent electrodes, configurations according to this embodiment of the present invention (where a light emitting device LEDV is alongside the electrodes of a touch pad) can also provide other benefits. For instance, light emitted from light emitting devices LEDV in  FIGS. 16E-16F  can reach surface  19  at a location remote from the electrodes of the touch pad while also being integrated according to the principles of the present invention.  FIGS. 17A-17J  illustrate the configurations of  FIG. 16A-16J  where the touch switches also include an integrated control circuit  32  proximate the touch detection electrodes  31  and  33 . 
       FIGS. 18A-18D  illustrate a touch switch with integrated control circuit where light emitting device LEDV and an aperture  53  in touch detection electrode  31  are aligned with window  54  in substrate  20 . In  FIG. 18D , showing a cross-section view of the assembled touch switch with integrated control circuit and light emitting device, decorative layer  51  is disposed on substrate  20  atop electrodes  31  and  33 . Decorative layer  51  is preferably either transparent or translucent, at least in an area aligned with light emitting device LEDV and window  54 , to allow light from light emitting device LEDV to reach surface  18  of decorative layer  51 .  FIG. 18A  shows electrodes  31  and  33  coupled to traces  34  and  35 , respectively. In  FIG. 18A , electrode  31  includes aperture  53 .  FIG. 18B  shows integrated control circuit  32  coupled to traces  34  and  35 . In  FIG. 18B , trace  35  is also coupled to light emitting device LEDV.  FIGS. 18C and 18D  show the configurations of  FIGS. 18A and 18B  assembled together. In  FIGS. 18C and 18D , aperture  53  is shown aligned with light emitting device LEDV. In  FIG. 18D , substrate  20  is shown with window  54 , which is also aligned with light emitting device LEDV. Window  54  is preferably also either translucent or transparent to allow light from light-emitting device LEDV to reach surface  18  of decorative layer  51 . Alternatively, substrate  20  could be entirely translucent or transparent in place of incorporating window  54  into substrate  20 . The touch switch depicted in  FIG. 18D  also has decorative layer  51 , which can have a translucent portion (not shown) aligned with window  54  of substrate  19  or can be completely translucent and the like. Since electrodes  31  and  33  are on side  19  of substrate  20  opposite the side bearing integrated control circuit  32  and light emitting device LEDV, traces  34  and  35  must penetrate substrate  20  to be coupled to electrodes  31  and  33  as well as integrated control circuit  32  and light emitting device LEDV. 
       FIG. 19  illustrates an arrangement of four touch pads electrically coupled to four light emitting devices. In  FIG. 19 , light emitting devices LEDV 1 -LEDV 4  are coupled to touch pads TP 1 -TP 4 , respectively, and both touch pads TP 1 -TP 4  and corresponding light emitting devices LEDV 1 -LEDV 4  are coupled to input/output pins P 1 -P 4 , respectively, which in turn can be coupled to an integrated control circuit (not shown). As shown in  FIG. 19 , light emitting devices LEDV 1 -LEDV 4  can be remote from the touch pads of a touch switch and can at the same time be integrated according to the present invention. 
       FIGS. 20A and 20B  depict a touch switch having an electroluminescent device borne on substrate  20  including electrodes  221  and  223  separated from electroluminescent layer  122  by insulating layers  150 . In  FIG. 20B , an alternating current source AC is coupled to electrodes  221  and  223 . Electrode  221  is preferably either transparent or translucent to allow light from the electroluminescent device to reach surface  19  of substrate  20 . The lighting operation of the electroluminescent device will be understood by those skilled in the art of electroluminescent devices. Also shown schematically in  FIG. 20B  are capacitances C touch  and C AC , which represent the capacitance across substrate  20  and across the electroluminescent device including insulating layers  150  and electroluminescent layer  122 , respectively. 
       FIG. 21A  illustrates a possible configuration of inputs to and outputs from a logic circuit  40  for the touch switch with integrated electroluminescent device of  FIGS. 20A-20B . In  FIG. 21A , surface  19  and electrodes  221  and  223  form capacitances C touch  and C AC , as also shown in FIG.  20 B. Electrode  221  is coupled through trace DRIVE  2  to the drains of active devices M 33  and M 34 , the gates of which are coupled to outputs DRIVE  2 H and DRIVE  2 L, respectively, of logic circuit  40 . Electrode  223  is coupled through outputs DRIVE  1  to the drains of active devices M 31  and M 32 , the gates of which are coupled to outputs DRIVE  1 H and DRIVE  1 L, respectively, of logic and decision circuit  40 . Electrode  221  in also coupled to input RETURN  1  and to resistance R 1 , which is coupled to the drain of active device M 40 , the gate of which is coupled to output SELECT  1  of logic and decision circuit  40 .  FIG. 21B  illustrates a timing diagram for the configuration in FIG.  21 A. Electrodes  221  and  223  receive alternating current signals from signal source AC (shown in FIG.  20 B), which, in  FIG. 21A , can originate in logic and decision circuit  40  and is communicated on traces DRIVE  1 H, DRIVE  1 L, DRIVE  2 H and DRIVE  2 L. The operation of the buffering configurations of active devices M 31  and M 32  and active devices M 33  and M 34 , will be understood to allow an alternating current to develop on traces DRIVE  1  and DRIVE  2  when appropriately signaled by logic and decision circuit  40 .  FIG. 21B  shows how the signals on traces DRIVE  1  and DRIVE  2  are opposite one another such that when the signal on trace DRIVE  1  is high, the signal on trace DRIVE  2  is low, and vice versa. 
     The light emitting electroluminescent device depicted in  FIG. 20B  can function as a touch switch when configured and signaled as shown in  FIGS. 21A-21B . Trace DRIVE  1  will be high when output DRIVE  1 H is high, biasing on active device M 31  and allowing voltage PLUS to appear on trace DRIVE  1 . When output SELECT  1  of logic and decision circuit  40  is high, as shown in  FIG. 21B , active device M 40  will allow current to pass through resistance R 1  such that a voltage will develop on input RETURN  1 . Also, when output SELECT  1  is high, the no signal appears on trace DRIVE  2 . The voltage appearing on input RETURN  1  will be one value when no stimulus appears at surface  19  and a lower value when a stimulus does appear at surface  19 . Specifically, a stimulus at surface  19  will increase the effective capacitance C touch  and shunt to ground current that would otherwise develop a high voltage across resistance R 1 . This increased effective capacitance and shunting to ground will correspond to a smaller voltage associated with the stimulated state on trace DRIVE  2  and input RETURN  1  than would develop if there were no stimulus and no increased capacitance. This is shown in FIG.  21 B. The configuration of FIG.  21 A and the timing shown in  FIG. 21B  are illustrative only. Other configurations and other timing patterns, using either the configuration of  FIG. 21A  or another configuration, are possible as well, and will be understood by those skilled in the art of circuit design. 
       FIG. 22A  illustrates a possible configuration of the input lines of a logic circuit for a two-by-two matrix of electroluminescent light emitting touch switches. In  FIG. 22A , four electroluminescent touch switches ELTS 1 -ELTS 4  are arranged in a two-by-two matrix and coupled through buffering devices including active devices M 31 -M 38  to logic and decision circuit  40 . Each electroluminescent touch switch operates in a manner similar to the manner described with reference to  FIGS. 21A and 21B .  FIG. 22B  illustrates a timing diagram for the configuration in FIG.  22 A. The configuration in FIG.  22 A and the timing diagram of  FIG. 22B  illustrate how either one of two electroluminescent touch switches ELTS 1 -ELTS 4  in a two touch switch column can create a signal on an input line RETURN  1  or RETURN  2  associated with a stimulated state of the column. For instance, either touch switch ELTS 2  or ELTS 4  can be stimulated, shunt current and reduce the voltage on input RETURN  2 , coupled to resistance R 2  coupled to the drain of active device M 41 , when output SELECT  2  is high, as shown in FIG.  22 B. For a stimulus to touch switch ELTS 2  to create a reduced voltage on input RETURN  2 , trace DRIVE  1  must be high and creating a potential on electrode  223  of touch switch ELTS 2 . For a stimulus to touch switch ELTS 4  to create such a reduced voltage on input RETURN  1 , trace DRIVE  2  must be high. As discussed above, other configuration or timing schemes are possible as well, as will be understood from the foregoing description. 
       FIG. 23  illustrates a touch switch with a liquid crystal integrated light emitting device that can replace the electroluminescent touch switches in the schematics of  FIGS. 21A and 22A . In  FIG. 23  alternating signal source AC is coupled to electrodes  221  and  223 , which are on either side of liquid crystal layer  222  and are supported by spacers  64 . Glass layer  60  and polarizer layer  62  are, in turn, on the outermost side of electrodes  221  and  223 . Electrodes  221  and  223  form capacitance C AC  and topmost glass and polarizer layers  60  and  62  form capacitance C touch . The light emitting operation of the liquid crystal light emitting device of  FIG. 23  will be understood by those skilled in the art and the touch switch operation will be understood from the foregoing description of  FIGS. 21A-22B . 
     Although some embodiments of the present invention have been described and illustrated using only one specific type of touch sensor, e.g., a touch sensor with integrated control circuit, it will be understood that any embodiment of the present invention can be used in conjunction with any type of touch switch. Moreover, the various aspects of the present invention described above can be combined in any way according to the requirements of the application for which the touch sensor is intended. The invention may also be embodied in other forms not explicitly depicted in a drawing without departing from its spirit or essential character. The described embodiments are to be considered in all respects only as illustrative and not restrictive. The scope of the invention is indicated by the appended claims rather than by the foregoing description. All changes which come within the meaning and range of equivalency of the claims therefore are to be embraced within that scope.