Abstract:
The invention relates to a user interface device ( 10 ) comprising a matrix of photon sensors ( 12 ), adapted for detecting variations in the shadow of an actuation member ( 16 ) and for deducing therefrom an item of information representative of a variation of position of the actuation member.

Description:
BACKGROUND 
       [0001]    The present disclosure relates to a user interface device, or man-machine interface. 
       DISCUSSION OF THE RELATED ART 
       [0002]    User interface devices controllable by simple sliding of a finger or of the hand on a touch-sensitive surface, or touch surface, have already been provided. The touch surface may be superimposed over a display, which enables to form an interactive user interface, or touch screen. 
         [0003]    Touch screens and surfaces are currently used in many fields. As an example, they have already been used to control cell phones, computers, television sets, motor vehicles, ticket vending machines, industrial equipment, medical equipment, etc. 
         [0004]    A disadvantage of this type of interface is that the contact with the users&#39; fingers tends to rapidly get the touch surface dirty. This implies the necessity to provide a regular cleaning, in particular in case of use in dirty environments (factories, public transports, etc.). Touch surfaces further raise a hygiene issue, in particular in hospitals where they may be a disease transmission vector. Further, the operation of touch surfaces is generally degraded when the user is wearing gloves. This may be a problem in certain fields of application (industry, surgery, outdoor use by cold weather, ticket vending machines for ski resorts, etc.). 
         [0005]    Patent application US20080297487 describes the use of one or a plurality of proximity sensors in combination with a touch screen, to detect events such as the passing of an actuating element (finger, hand, object, etc.) above the screen. This enables the user to perform certain actions without having to touch the touch surface. The proximity sensors described in said document comprise at least one infrared emitter and at least one infrared receiver. In operation, the sensor permanently emits an infrared radiation. When a finger, a hand, or an object passes close to the sensor, part of the emitted infrared radiation is reflected towards the receiver, and the sensor deduces therefrom information relative to the presence of an object close to the touch surface. 
         [0006]    A disadvantage of this type of device is that the emission of the infrared radiation by the proximity sensors causes an unwanted power overconsumption. 
         [0007]    It would be desirable to have a contactless user interface device capable of operating without emitting any radiation. 
         [0008]    Further, touch surfaces, touch screens, and proximity sensors of the above-mentioned type are relatively complex to form. 
         [0009]    It would be desirable to be able to more easily form touch and contactless surfaces and screens. It would further be desirable to be able to form such devices on all types of support and in particular on flexible supports such as plastic, paper, cardboard, or fabric, on large supports (advertisement panels), or on disposable supports such as packages of convenience goods. 
         [0010]    It has already been provided to form electronic components, such as transistors, light-emitting diodes, and photodetectors, based on organic conductive and semiconductive materials. Such materials have the advantage of being easier to deposit and less fragile than inorganic conductive and semiconductive materials (for example, silicon) used in conventional technological processes. 
         [0011]    The forming of organic semiconductor components however remains rather complex. In particular, it is necessary to provide low-pressure vapor deposition phases and anneal phases at relatively high temperatures, for example, higher than 250° C. As a result, such components can only be formed of particularly robust supports, and by means of relatively expensive equipment. Further, the juxtaposing of such components on large surface areas is difficult since it is difficult (or too expensive) for deposition equipment to treat supports of large dimensions (for example, having a diameter greater than 30 cm). 
         [0012]    It would further be desirable, for example, in the field of advertising or communication, to be able to form a display surface capable of displaying an animation and offering possibilities of interaction with a user. 
       SUMMARY 
       [0013]    Thus, an object of an embodiment of the present invention is to provide a user interface device overcoming at least some of the disadvantages of existing devices. 
         [0014]    According to a first aspect, an object of an embodiment of the present invention is to provide a user interface device capable of being actuated without any contact with the user. 
         [0015]    Another object of an embodiment of the present invention is to provide a contactless user interface device capable of operating without emitting any radiation. 
         [0016]    According to a second aspect, an object of an embodiment of the present invention is to provide a user interface device based on organic conductive and semiconductor materials. 
         [0017]    Another object of an embodiment of the present invention is to provide a user interface device which is easier to manufacture than existing devices. 
         [0018]    Another object of an embodiment of the present invention is to provide a user interface device capable of being formed on a greater variety of supports than current devices, and particularly on low-cost supports such as plastic, paper, fabric, etc. 
         [0019]    According to a third aspect, an object of an embodiment of the present invention is to provide an interactive user interface device capable of being used for advertising or communication purposes. 
         [0020]    Thus, an embodiment of the present invention provides a user interface device comprising an array of photon sensors, capable of detecting variations of the shadow of an actuating element and of deducing therefrom information representative of a position variation of the actuating element. 
         [0021]    According to an embodiment of the present invention, the device is capable of deducing from the shadow variations information representative of a distance variation between the actuating element and the array of sensors. 
         [0022]    According to an embodiment of the present invention, the device is capable of detecting variations of the light intensity level received by the sensors, and of deducing therefrom information representative of a distance variation between the actuating element and the sensor array. 
         [0023]    According to an embodiment of the present invention, the device is capable of deducing from the shadow variations information representative of a variation of the position of the actuating element parallel to the sensor array. 
         [0024]    According to an embodiment of the present invention, the device comprises no optical system between the sensor array and the actuating element. 
         [0025]    According to an embodiment of the present invention, a translucent protection layer coats the sensor array. 
         [0026]    According to an embodiment of the present invention, the surface area of the sensor array is larger than the surface area of the actuating element opposite to said array. 
         [0027]    According to an embodiment of the present invention, the actuating element is at a distance greater than ten centimeters away from the sensor array. 
         [0028]    According to an embodiment of the present invention, this device further comprises an array of light display pixels. 
         [0029]    According to an embodiment of the present invention, the photons sensors are made of transparent materials. 
         [0030]    According to an embodiment of the present invention, the device further comprises an array of infrared emitters. 
         [0031]    According to an embodiment of the present invention, the device further comprises a darkness sensor and means for activating the infrared emitters when the brightness is lower than a threshold. 
         [0032]    According to an embodiment of the present invention, the photon sensors are organic sensors formed by deposition of organic conductive and semiconductive materials in liquid form on a dielectric support. 
         [0033]    According to an embodiment of the present invention, the dielectric support is made of a material from the group comprising glass, plastic, paper, cardboard, and fabric. 
         [0034]    Another embodiment of the present invention provides an interactive display surface comprising a user interface device of the above-mentioned type, and display means formed by deposition of organic conductive and semiconductive materials in liquid form on the dielectric support. 
         [0035]    Another embodiment of the present invention provides a method of manufacturing a user interface device of the above-mentioned type, wherein the sensors are formed at a temperature smaller than 150° C. and at the atmospheric pressure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0036]    The foregoing and other features and advantages will be discussed in detail in the following non-limiting description of specific embodiments in connection with the accompanying drawings, among which: 
           [0037]      FIG. 1  is a perspective view schematically showing an embodiment of a user interface device; 
           [0038]      FIG. 2  is a cross-section view of the user interface device of  FIG. 1 ; 
           [0039]      FIG. 3  is a perspective view schematically showing an alternative embodiment of a user interface device; 
           [0040]      FIG. 4  is a cross-section view showing another alternative embodiment of a user interface device; 
           [0041]      FIGS. 5A and 5B  are cross-section views schematically and partially showing an embodiment of a user interface device based on organic conductive and semiconductive materials; 
           [0042]      FIG. 6  is a cross-section view schematically and partially showing an alternative embodiment of the device of  FIGS. 5A and 5B ; and 
           [0043]      FIG. 7  schematically shows an embodiment of an interactive display surface capable of being used for advertising purposes. 
       
    
    
     DETAILED DESCRIPTION 
       [0044]    For clarity, the same elements have been designated with the same reference numerals in the various drawings and, further, as usual in the representation of integrated circuits, the various drawings are not to scale. Further, only those elements which are useful to the understanding of the present invention have been shown and will be described. In particular, what use is made of the user interface devices described hereafter has not been detailed. It will be within the abilities of those skilled in the art to use the provided devices in any type of system capable of being controlled via a touch and/or contactless interface. Further, the means for processing the information provided by the user interface devices described hereafter and the means of connection with the system(s) to be controlled are within the abilities of those skilled in the art and will not be described. 
         [0045]    A first aspect of an embodiment of the present invention provides a user interface device capable of detecting variations of the shadow of an actuating element on an array of photons sensors, or photodetectors, and of deducing therefrom information representative of a position variation of the actuating element. 
         [0046]    It should be noted that position of the actuating element here means a position relative to the interface device. A usage mode where the user interface device itself is displaced, the actuating element remaining fixed, may in particular be provided. 
         [0047]      FIGS. 1 and 2  schematically show an embodiment of a user interface device  10 .  FIG. 1  is a perspective view of device  10 , and  FIG. 2  is a cross-section view along plane  2  of  FIG. 1 . 
         [0048]    Device  10  comprises an array of photon sensors or photodetectors  12  ( FIG. 2 ). In this example, sensors  12  are arranged on a planar surface. Embodiments may however be provided where sensors  12  are arranged on a non-planar surface. Sensor array  12  may be topped with a transparent or translucent protection coating  14 , for example, a glass plate or a plastic coating. 
         [0049]    Device  10  is capable of detecting variations of the cast shadow of an actuating element  16  on sensor array  12 , when the actuating element is located between a light source and the array. 
         [0050]    Actuating element  16  may be the user&#39;s finger, hand, or any other object. The light source is preferably ambient light, for example, the sun or the indoor electric lighting of a room in a building. 
         [0051]    In this example, actuating element  16  is placed directly opposite to sensor array  12 , that is, no optical system is provided between the array and the actuating element. The surface area taken up by the sensor array is preferably greater than the surface area of the projection of the actuating element on the plane of this array. More generally (in particular, if sensor array  12  does not occupy a planar surface), the surface area of sensor array  12  is greater than the surface area of the actuating element opposite to this array. 
         [0052]    In a preferred embodiment, device  10  is capable of detecting displacements of the actuating element in a plane parallel to the plane of sensor array  12 , and variations of distance Z between the actuating element and sensor array  12 . 
         [0053]    For this purpose, in an initialization phase, device  10  measures the ambient brightness, that is, the light intensity received by each sensor  12  when no actuating element is placed opposite to sensor array  12 . 
         [0054]    When actuating element  16  is placed between the light source and the sensor array, the cast shadow of the actuating element on the sensor array decreases the light intensity received by some of sensors  12 . This enables device  10  to detect the presence of actuating element  16  in the vicinity of the array and, possibly, to follow the displacements of the actuating element in a plane parallel to the plane of the array (or parallel to the surface area taken up by the array if this surface is not planar). 
         [0055]    When distance Z between the actuating element and sensor array  12  varies, the light intensity level received by sensors  12  also varies. In particular, when actuating element  16  is brought closer to sensor array  12 , the light intensity received by sensors  12  in the shade of the actuating element decreases, and when actuating element  16  is drawn away from the sensor array, the light intensity increases. Device  10  is capable of deducing, from intensity variations of the cast shadow of the actuating element, information relative to the variations of distance Z between the actuating element and the sensor array. In an alternative embodiment, a calibration phase creating a correspondence between the intensity level of the cast shadow of the actuating element and the distance between actuating element and sensors  12  may be provided. This enables device  10  to measure distance Z between the actuating element and sensors  12 . 
         [0056]    Thus, in a preferred embodiment, device  10  is capable of detecting the position in three dimensions of actuating element  16  in the space located opposite to the sensor array. 
         [0057]    Although this has not been shown in the drawings, device  10  may comprise means for processing the signals delivered by sensors  12  (for example, a microprocessor), and means of communication with a device or a system to be controlled (wire or wireless link). 
         [0058]    Further, and although this has not been shown, each photodetector  12  may comprise a focusing lens, for example, a Fresnel lens. A lens array also forms an interface between the photosensitive region of photodetector array  12  and coating  14 , or is integrated to coating  14 . The provision of lenses enables to improve the lateral resolution of detection of the actuating element, particularly when it is remote from device  10 . 
         [0059]    An advantage of interface device  10  described in relation with  FIGS. 1 and 2  is that it is capable of being actuated without any contact with the user. It should however be noted that device  10  may also operate as a touch surface, that is, if the user slides his finger on the upper surface of the device (upper surface of protection coating  14  in this example), the device will be capable of determining the position in two dimensions of the actuating element on the sliding surface (distance Z equal to the thickness of protection coating  14 ). 
         [0060]    Another advantage of interface device  10  is that it enables to provide information relative to the distance between the actuating element and sensors  12 . This for example enables to implement applications for the control of three-dimensional virtual objects, or three-dimensional navigation. 
         [0061]    Another advantage of interface device  10  is that it does not require, in order to operate, the emission of an infrared radiation or other, which enables to minimize its electric power consumption. 
         [0062]    In the above-described embodiment, the shadow of the actuating element, cast on the detection surface, is used to obtain information relative to the position of the actuating element. The image of the actuating element, seen by the photon sensors, may also be used. It should be noted that in practice, the cast shadow and the image of the actuating element do not coincide, except if the light source is placed exactly in the axis of the projection of the actuating element on the sensor array. As a variation, device  10  may detect both the cast shadow and the image of the actuating element to obtain more accurate information relative to the position or to the position variations of the actuating element. Device  10  for example comprises software for processing the signals delivered by the photodetector array, capable of detecting the cast shadow and possibly the image of the actuating element. 
         [0063]    In a preferred embodiment, device  10  is capable of operating (that is, of detecting the cast shadow of the actuating element) when actuating element  16  is located at a distance greater than 10 cm away from the sensor array, for example, a distance in the range from 10 cm to 1 m. 
         [0064]      FIG. 3  is a cross-section view showing an alternative embodiment where a user interface device  30  comprises a display screen, to form an interactive interface. 
         [0065]    Device  30  of  FIG. 3  comprises the same elements as device  10  of  FIGS. 1 and 2 , and further comprises an array  32  of light display (or backlighting) pixels. In this example, pixels  32 , for example, light-emitting diodes, are arranged in a plane parallel to photodetector array  12 , and between the photodetector array and protection coating  14 . Photodetector array  12  and pixel array  32  are stacked with a slight offset so that, in top view, pixels  32  do not face sensors  12 , which would mask sensors  12  and would prevent the detection of the cast shadow of the actuating element. 
         [0066]    In an alternative embodiment, photon pixel array  12  is placed between display pixel array  32  and protection coating  14 . In this case, stacked  12  and pixels  32  may be stacked with no offset, provided for sensors  12  to be made of transparent or translucent materials. 
         [0067]    In another alternative embodiment, the detection and display arrays are not stacked, but are made in a same level of the stack of conductive and semiconductive arrays (alternation of pixels  32  and of sensors  12 ). 
         [0068]    It should be noted that the display screen associated with interface device  30  is not necessarily a light-emitting diode display, but may also be formed with any other adapted technology. 
         [0069]    Further, in another alternative embodiment, instead of being stacked to the user interface device, the display screen is separate and connected to the interface device by a wire or wireless link. 
         [0070]      FIG. 4  is a cross-section view showing another alternative embodiment where a user interface device  40  comprises infrared proximity detectors. Device  40  of  FIG. 4  comprises the same elements as device  10  of  FIGS. 1 and 2 , and further comprises an infrared emitter array  42 . In operation, each of emitters  42  permanently emits an infrared radiation. When actuating element  16  passes over an emitter  42 , part of the emitted radiation is reflected towards a neighboring photodetector  12 , which can deduce information relative to the presence of an object above the interface. Thus, infrared detectors  42 , in combination with photodetectors  12 , enables device  40  to implement the same functions of detection of the position variations of actuating element  16  as photodetectors  12  alone used as shade detectors. 
         [0071]    An advantage of infrared detection over shade detection is that its operation is independent from the ambient lighting and thus more robust. In particular, infrared detection may operate in the dark, in the absence of any external light source. It may be provided to alternate between a low-consumption operating mode, based on the detection of the cast shadow of the actuating element by photodetectors  12  when the ambient lighting allows it, and an infrared operating mode when the lighting conditions do not allow the cast shadow detection. 
         [0072]    A darkness sensor may for example be provided to automatically switch from the low-consumption mode to the infrared mode when the ambient luminosity becomes too low to allow the cast shadow detection. 
         [0073]    An infrared emission (by emitters  42 ) with a frequency modulation may be provided, which enables, on reception by photodetectors  12 , to discriminate shade from infrared. This enables to simultaneously use the infrared operation and the cast shadow detection operation to obtain more accurate information relative to the position of the actuating element. 
         [0074]    The infrared emission with a frequency modulation further enables to decrease the power consumption of the infrared source. 
         [0075]    As in the example described in relation with  FIG. 3 , interface device  40  may be associated with a display screen, not shown in  FIG. 4 . 
         [0076]    According to a second aspect of an embodiment of the present invention, a user interface device based on organic conductive and semiconductive materials is formed. 
         [0077]      FIGS. 5A and 5B  are cross-section views schematically and partially showing an embodiment of a user interface device  50  based on organic conductive and semiconductive materials.  FIG. 5B  is a cross-section view in plane B of  FIG. 5A , and  FIG. 5A  is a cross-section view in plane A of  FIG. 5B . 
         [0078]    Device  50  comprises an array of photon sensors, or photodetectors  52 , preferably capable of detecting variations of the cast shadow of an actuating element (not shown in  FIGS. 5A and 5B ). In this example, photodetectors  52  are formed on a surface of a transparent or translucent dielectric substrate or support  54 , for example, made of glass or plastic. Each photodetector  52  comprises a stack comprising, in the following order from substrate  54 : a transparent electrode  56 , for example, made of indiumtin oxide (ITO); a layer  58  of a heavily-doped transparent organic semiconductor polymer (electron donor layer), for example, a polymer known as PEDOT:PSS, which is a mixture of poly(3,4)-ethylenedioxythiophene and of polystyrene sodium sulfonate; a layer  60  made of an organic semiconductor polymer, for example, poly(3-hexylthiophene) or poly(3-hexylthiophene-2,5-diyl) (P-type semiconductor), known as P3HT, or [6,6]-phenyl-C 61 -methyl butanoate (N-type semiconductor), known as PCBM; a layer  61  made of a heavily-doped organic semiconductor polymer (hole donor layer); and an electrode  62 , for example, made of aluminum or silver. Lower electrodes  56  have, in top view, the shape of parallel strips, each strip  56  addressing all the photodetectors of a same row R ( FIG. 5A ) of the array. Upper electrodes  62  have, in top view, the shape of strips orthogonal to electrodes  56 , each strip  62  addressing all the photodetectors of a same column C ( FIG. 5B ) of the array. In this example, lower electrode layer  56  extends continuously under each row R of photodetectors  52  of the array, and upper electrode layer  62  extends continuously on each column C of photodetectors  52  of the array. Laterally, semiconductor regions  60  of photodetectors  52  are separated from one another by a dielectric material  64 . Further, a transparent protection coating  65  covers the upper surface of the array (side of electrodes  62 ). 
         [0079]    In this example, photodetectors  52  are intended to be illuminated through transparent substrate  54  (and through transparent layers  56  and  58 ). In  FIGS. 5A and 5B , the incident radiation is shown by arrows  67 , on the side of substrate  54 . 
         [0080]      FIG. 6  is a cross-section view schematically and partially showing an alternative embodiment of device  50  of  FIGS. 5A and 5B . The device of  FIG. 6  differs from the device of  FIGS. 5A and 5B  in that the order of photodetector layers  52  is inverted.  FIG. 6  is a cross-section view along a column C of photodetectors. The corresponding cross-section (along a row) has not been shown. 
         [0081]    In this example, each photodetector  52  comprises a stack comprising, in the following order from substrate  54 , an electrode  62 , for example, made of aluminum or of silver, a layer  61  made of a heavily-doped organic semiconductor polymer (hole donor layer), a layer  60  made of organic semiconductor polymer, a layer  58  of heavily-doped transparent organic semiconductor polymer (electron donor layer), and a transparent electrode  56 . A transparent protection coating  65  covers the upper surface of the array (on the side of electrodes  56 ). 
         [0082]    Photodetectors  52  are here intended to be illuminated through protective coating  65  (and through transparent layers  56  and  58 ). In  FIG. 6 , the incident radiation is shown by arrows  69 , on the side of transparent coating  65 . 
         [0083]    It is here provided to form device  50  by printing techniques. The materials of above-mentioned layers  56  to  65  are deposited in liquid form, for example, in the form of conductive and semiconductive inks by means of inkjet printers. It should here be noted that materials in liquid form here also means gel materials capable of being deposited printing techniques. Anneal steps may be provided between the depositions of the different layers, but the anneal temperatures cannot exceed 150° C., and the deposition and the possible anneals can be performed at atmospheric pressure. 
         [0084]    The forming of organic semiconductor components by printing techniques is for example described in article “CEA-LITEN S2S printing platform for Organic CMOS and Sensors Devices” by Jean-Yves Laurent et al, LOPE-C Conference, June 2011, Frankfurt. 
         [0085]    An advantage of device  50  is that it can be more easily formed than existing devices. In particular, it may be formed on a greater variety of surfaces, and particularly on larger surface areas and on any type of substrate, including on substrates having no resistance to heat, for example, flexible substrates made of plastic, paper, cardboard, fabric, etc. It should be noted that in the device of  FIGS. 5A and 5B , if the substrate is opaque, upper electrode  62  may be made of a transparent conductive material, and the device may be illuminated on its front side (in the orientation of the drawing). 
         [0086]    Further, device  50  may be formed by using equipment (printing deposition equipment) compatible with industrial package manufacturing equipment, plastics engineering, etc. 
         [0087]    Another advantage of device  50  is that its cost is relatively low, since the equipment necessary for its manufacturing (printing deposition equipment) is less expensive than the equipment necessary to form inorganic semiconductor devices, and also less expensive than usual equipment used to form organic semiconductor components (low-pressure vapor deposition and high-temperature anneal equipment). 
         [0088]    Various alterations, modifications, and improvements will readily occur to those skilled in the art. In particular, it will be within the abilities of those skilled in the art to provide any adapted stack of layers, other than those described in relation with  FIGS. 5A ,  5 B, and  6 , to form a photodetector. It may particularly use conductive, semiconductor, and dielectric materials capable of being deposited in liquid form, other than those mentioned hereabove. 
         [0089]    More generally, it is provided to form touch or contactless user interface devices where semiconductor components are formed by deposition of liquid organic conductive and semiconductive materials on a dielectric support. Apart from the photodetector array, a display array (see  FIG. 3 ) or infrared proximity sensors (see  FIG. 4 ) may also be formed by printing of organic materials. A preferred application where the invention is particularly advantageous concerns devices of the type described in relation with  FIGS. 1 to 4 . 
         [0090]    Further, although this has not been mentioned hereabove, it may be provided to have, in the photodetector array, one or several access transistors associated with each photodetector (active array). The transistors may also be formed from organic semiconductor materials in liquid or gel form, by printing techniques. 
         [0091]    According to a third aspect of an embodiment of the present invention, an interactive display surface capable of being used, for example, for advertising purposes, is provided. 
         [0092]      FIG. 7  is a perspective view schematically showing an embodiment of an interactive display surface  70 . 
         [0093]    Surface  70  comprises a display area (or screen)  72 . The display area preferably has relatively large dimensions. Preferably, area  72  extends over a surface area greater than 3 m 2 . Display area  72  is formed by deposition of organic conductive and semiconductive materials in liquid form on a dielectric support, by printing techniques. As an example, surface  70  is formed on a paper or plastic poster, on a glass shop window, on cardboard, or on fabric, etc. Such supports may be used as the dielectric support having display area  72  printed thereon. If need be, an interface dielectric layer may be deposited by printing on the support, for example, if the support is porous or does not have satisfactory dielectric properties. Display area  72  for example is an organic light-emitting diode screen. The forming of organic light-emitting diodes by printing techniques is for example described in above-mentioned article “CEA-LITEN S2S printing platform for Organic CMOS and Sensors Devices”. More generally, display area  72  may be formed in any other technology enabling to form a display screen by deposition of organic conductive, semiconductor, and dielectric materials in liquid form. As an example, area  72  may be made from light-emitting organic materials. 
         [0094]    Surface  70  comprises at least one photosensitive presence detector  74  (two detectors  74  in the shown example). In this example, surface  70  is formed on a glass shop window, and detectors  74  are placed towards different ends of the shop window (bottom left-hand side and bottom right-hand side) and capable of delivering a signal when a passer-by  76  (user) or an object is in front of one or the other of these ends, in the detector range. Detectors  74  may be a simple photodiode or photoresistor, an infrared proximity detector, an array of photon sensors of the type described in relation with  FIGS. 1 to 6 , or any other photosensitive detector. In any event, detectors  74  are formed by deposition of organic conductive and semiconductive materials in liquid form on a dielectric support, by printing techniques. 
         [0095]    A control unit  77  is provided to control display area  72  and have it display an animation (for example, an image, a slide-show, or a video) or, more generally, information, when sensors  74  detect the presence of a user in front of the shop window. Control unit  77  may be formed by discrete electronic components, or by integrated circuits (unit  77  for example comprises a microcontroller). Control unit  77  may be placed on surface  70 , for example by gluing or embedding, or transferred and housed in a package external to surface  70 . As a variation, control unit  77  may, like display area  72  and photosensitive sensors  74 , be produced in printed organic electronics, directly on surface  70 . Connections  78  between control unit  77 , display area  72 , and detectors  74 , may be wireless or wired. Conductive tracks made of a transparent conductive material capable of being deposited in liquid form may for example be printed on surface  70 . 
         [0096]    In the shown example, a sound emission device  80 , for example comprising one or several loudspeakers, is further provided. This enables to provide, apart from the visual animation displayed on display area  72 , an audio animation. The audio device may be formed in any known technology, for example, based on piezoelectric materials. Device  80  may be placed on surface  70 , for example, by gluing or embedding, or be external to surface  70 . In a preferred embodiment device  80  is made of materials capable of being deposited in liquid form (for example, comprising an organic piezoelectric material), and directly formed on surface  70  by printing techniques. 
         [0097]    For its electric power supply, interactive surface  70  may be connected to an electric power supply network (such as the mains) or to a battery. If the electric power supply needs of surface  70  are not too high, a battery made of materials capable of being deposited in liquid form, directly printed on surface  70 , may be used. 
         [0098]    As an example of use, an advertising device comprising a large interactive contactless surface may be provided (for example, in the order of several square meters), capable of starting the display of an animation as soon as a person (user) passes by the surface. 
         [0099]    In an alternative embodiment, several presence detectors  74  may be provided at different points of surface  70 . The control unit may then be programmed to vary the animation according to the user&#39;s position in front of the surface (multiple starts). 
         [0100]    In another alternative embodiment, an array of photodetectors of the type described in relation with  FIGS. 1 to 6  may be superimposed to display area  72 . The photodetector array then plays the role of presence detectors  74 . Such an embodiment enables to implement an interactive animation, that is, reacting to the user&#39;s actions (displacements, position changes, motions towards or away from the surface, etc.). 
         [0101]    Various embodiments have been described, various alterations and modifications will occur to those skilled in the art. 
         [0102]    In particular, the interactive display surface described in relation with  FIG. 7  may be used for other applications than the animation of a shop window. More generally, such an interactive display surface may be used for any type of advertising or communication application. It will for example be within the abilities of those skilled in the art to adapt the provided operation to form interactive packages for commercial products (food products or others). 
         [0103]    The practical implementation of the present invention is within the abilities of those skilled in the art based on the functional indications described hereabove and using technologies known per se.