Abstract:
A self-service terminal having an acoustic interface is described. The terminal comprises a user locating mechanism, a controller, and an array of individually controllable acoustic elements. In use, the locating mechanism is operable to locate a user and to convey user location information to the controller, and the controller is operable to focus each acoustic element to the user&#39;s location to increase the privacy of the user in using the terminal. A method of interacting with a self-service terminal is also described.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a self-service terminal (SST). In particular, the invention relates to an SST having an acoustic interface for receiving and/or transmitting acoustic information, such as a voice-controlled ATM. 
     Voice-controlled ATMs allow a user to conduct a transaction by speaking and listening to an ATM; thereby obviating the need for a conventional monitor. In some voice-controlled ATMs a biometrics identifier, such as a human iris recognition unit, is used to avoid the user having to insert a card into the ATM. When a biometrics identification unit is used, there is no requirement for a conventional keypad. 
     Voice-controlled ATMs make the human to machine interaction at an ATM more like a human to human interaction, thereby improving usability of the ATM. Voice-controlled ATMs also improve access to ATMs for people having certain disabilities, such as visually-impaired people. 
     Although voice-controlled ATMs have a number of advantages compared with conventional ATMs, they also have some disadvantages. These disadvantages mainly relate to privacy and usability. 
     Some disadvantages relate to the ATM speaking to the user. For example, if an ATM that is located in a public area audibly confirms withdrawal of one hundred pounds, then the user may feel vulnerable to attack and may believe that there is a lack of privacy for the transaction, as passers-by may overhear the ATM confirming the large amount of cash to be withdrawn. 
     Other disadvantages relate to the user speaking to the ATM. For example, in noisy environments such as a busy street or a shopping center, the ATM may not be able to discriminate between the user&#39;s voice and background noise. The user may become frustrated by the ATMs failure to understand a command being spoken by the user; this may lead to the user shouting at the ATM, which further reduces the privacy of the transaction. 
     SUMMARY OF THE INVENTION 
     It is an object of an embodiment of the present invention to obviate or mitigate one or more of the above disadvantages or other disadvantages associated with SSTs having acoustic interfaces. 
     According to a first aspect of the present invention there is provided a self-service terminal having an acoustic interface characterized in that the terminal comprises a user locating mechanism, a controller, and an array of individually controllable acoustic elements; whereby, in use, the locating mechanism is operable to locate a user and to convey user location information to the controller, and the controller is operable to focus each acoustic element to the user&#39;s location. 
     It will be appreciated that the acoustic elements may be microphone or loudspeaker elements. When the acoustic elements are loudspeakers, the controller is operable to control the loudspeakers so that sound from the loudspeakers is only audible in the area in the immediate vicinity of the user. This ensures that the privacy of the user is increased. When the acoustic elements are microphones, the controller is operable to control the microphones so that only sound from the area in the immediate vicinity of the user is conveyed, thereby removing the effect of background noise. The microphone elements may detect all sound indiscriminately and the controller may operate on all the sound to mask out sound from areas other than the vicinity of the user. Alternatively, the microphone elements may only detect the sound from the vicinity of the user. 
     The term “focus” as used herein denotes directing the acoustic elements to a relatively small area or zone. Where the elements are microphones, when the microphones are focused audible signals are only conveyed from this zone, even if the microphones detect sound from areas outside this zone. Where the elements are loudspeakers, when the loudspeakers are focused they transmit audible signals to only this zone. 
     The zone may be defined by a certain angular beam width, for example, if a linear array is used and the array can focus anywhere between the angles of −45 degrees and +45 degrees relative to a line normal to the array, then the elements may be able to focus to a zone of five degrees, such as −20 to −15 degrees. The zone may be defined by an angular beam width and a distance, for example two meters from the array and at an angular beam width of −15 to −20 degrees. 
     Preferably, the locating mechanism uses visual detection to locate the user and to output user location information to the controller in real time. For example, the visual detection may be a stereo imager. One advantage of using a visual detection mechanism is that the user will be located accurately even though the background noise is louder than the user&#39;s voice; whereas, if an audio detection mechanism is used then the background noise may be targeted because it is the loudest noise being detected. 
     Another advantage of using a visual detection system is that the acoustic elements can be focused on the user prior to the user speaking to the SST, this ensures that all of the user&#39;s speech will be detected by the SST; whereas, if an audio detection mechanism is used, the user cannot be targeted until he/she speaks to the SST, so the first few words spoken by a user may not be detected very clearly. 
     Yet another advantage of using a visual detection system is that the visual system can continue detecting the user&#39;s position during a transaction, so that if the user moves then the acoustic elements can be re-focused to the user&#39;s new position. 
     In one embodiment where an SST includes an iris recognition unit, the stereo cameras that are used to locate the user&#39;s head may be modified to output a value indicative of the position of the user&#39;s head. This value may relate to the angular position of the user&#39;s head relative to a line normal to the array of elements. Some additional processing may be performed to locate the user&#39;s mouth and ears, as iris recognition units generally detect the location of a user&#39;s eye. 
     In less preferred embodiments, the locating mechanism may use an audio mechanism, such as acoustic talker direction finding (ATDF), for locating the position of a user. 
     Preferably, the array is a linear array. In more complex embodiments, the array may be a planar array for focusing a beam in two dimensions rather than one dimension. 
     In one embodiment the array may be an array of ultrasonic emitters or transducers that are powered by an ultrasonic amplifier, under control of an ultrasonic signal processor, to produce a narrow beam of sound. 
     The controller may control an array of microphones and an array of loudspeakers. The two arrays may be integrated into the same unit. 
     Preferably, the controller controls the array using a spatial filter to operate on the acoustic elements in the array. One suitable type of filter is based on the electronic beamforming technique, and is called “Filter and Sum Beamforming”. By using beamforming, the amplitude of a coherent wavefront can be enhanced relative to background noise and directional interference, thereby achieving a narrower response in a desired direction. In one implementation of a spatial filter, the controller includes a digital signal processor (DSP) and an associated memory, where the DSP applies a Finite Impulse Response filter to each element. 
     Alternatively, but less preferred, the controller may control the elements by adjusting the physical orientation of the elements. 
     Preferably, the memory is pre-programmed with a plurality of algorithms, one algorithm for each zone at which the elements can be focused. The algorithms comprise coefficients (which may include weighting and delaying values) for applying to each element. 
     Preferably, the DSP receives the user location information, accesses the memory to select an algorithm corresponding to the user location information, and applies the coefficients within the algorithm to the acoustic elements to focus the elements at the desired zone. 
     Preferably, each microphone element includes a transducer, a pre-amplifier, and an analog-to-digital (A/D) converter. Preferably, each loudspeaker element includes a power amplifier, a transducer, and a digital-to-analog converter (D/A). 
     By virtue of this aspect of the invention, the acoustic elements can be used to create a privacy zone around the user&#39;s head so that only the user can hear an SST&#39;s spoken commands, and the SST only listens to the user&#39;s spoken commands; thereby improving privacy and usability for the user, and the speech recognition of the terminal. 
     According to a second aspect of the present invention there is provided a self-service terminal having an acoustic interface characterized in that the terminal comprises a lo directional acoustic element array capable of interacting with a user located anywhere in a broad zone, a steering mechanism operable to direct the array to a narrow zone within the broad zone, and a locating mechanism operable to detect the location of a user within the broad zone and to inform the steering mechanism of the location of the user. 
     The broad zone may be at least five times the size of the narrow zone; preferably, the broad zone is at least ten times the size of the narrow zone; advantageously, the broad zone is at least sixteen times the size of the narrow zone. In one embodiment, the narrow zone is defined by an angular beam width of 5 degrees and the broad zone is defined by a beam angle of 90 degrees. 
     According to a third aspect of the invention there is provided a method of interacting with a user of an SST, characterized by the steps of detecting the location of the user and adjusting one or more acoustic element arrays to focus the arrays at the location of the user. 
     According to a fourth aspect of the invention there is provided a self-service terminal having an acoustic interface characterized in that the terminal comprises a user locating mechanism, a controller, and an array of individually controllable loudspeaker elements; whereby, in use, the locating mechanism is operable to locate a user and to convey user location information to the controller, and the controller is operable to direct first audio signals to the location of the user and second audio signals to other locations. 
     The first audio signals may relate to a transaction being conducted by the user. The second audio signals may be audio advertisements to passers-by or people waiting in a queue to use the SST. Alternatively, the second audio signals may be noise (such as white or pink noise) or warnings to increase the privacy of the user. Additional audio signals may also be used, so that the terminal may simultaneously transmit different audio signals to a user, to passers-by, to people queuing behind the user, and to people standing too close to the user. 
     The SST may include a proximity detector for detecting the presence or entrance of people within a zone around the user. On detecting a person within the zone around a user, the terminal may direct an audio signal to the person in the zone around the user. 
     By virtue of this aspect of the invention, a steerable loudspeaker array may be used to supply different audio information to a user of an SST than to those people who are in the vicinity of the SST, thereby creating an acoustic privacy shield for the user of the SST. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and other aspects of the invention will be apparent from the following specific description, given by way of example, with reference to the accompanying drawings, in which: 
     FIG. 1 is a schematic diagram of a user interacting with an SST according to one embodiment of the present invention; 
     FIG. 2 is a block diagram of the array controller of FIG. 1; 
     FIG. 3 is a simplified block diagram of the locating mechanism of FIG. 1; 
     FIG. 4 is a block diagram of the microphone array of FIG. 1; 
     FIG. 5 is a block diagram of the loudspeaker array of FIG. 1; 
     FIGS.  6 A,B,C are simplified schematic plan views of a user in three different positions at an ATM; and 
     FIG. 7 is a simplified schematic plan view of a user interacting with an ATM according to another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION 
     Referring to FIG. 1, there is shown an SST  10  in the form of an ATM. The ATM  10  has a acoustic interface  12  comprising two linear arrays  14 , 16  of acoustic elements. One linear array  14  comprises microphone elements, the other linear array  16  comprises loudspeaker elements, as will be described in more detail below. 
     Both arrays  14 , 16  are controlled by an array controller  18  incorporated in an ATM controller  20  that controls the operation of the ATM  10 . 
     The ATM  10  also includes a locating mechanism  22  in the form of an iris recognition unit, a cash dispenser unit  24 , a receipt printer  26 , and a network connection device  28  for connecting to an authorization server (not shown) for authorizing transactions. 
     The iris recognition unit  22  includes stereo cameras for locating the position of an eye of a user  30 . Suitable iris recognition units are available from “SENSAR” of 121 Whittendale Drive, Moorestown, N.J., USA 08057. Unit  22  has been modified to output the location of the user  30  on a serial port to the array controller  18 . It will be appreciated by those of skill in the art that the ATM controller  20  is operable to compare an iris template received from the iris unit  22  with iris templates of authorized users to identify the user  30 . 
     The array controller  18  is shown in more detail in FIG.  2 . Array controller  18  comprises a digital signal processor  40  and an associated memory  42  in the form of DRAM. The memory  42  stores an algorithm for each possible steering angle, so that for any given steering angle there is an algorithm having coefficients that focus the acoustic elements to a zone represented by that steering angle. The algorithms used are based on the Filter and Sum Beamforming technique, which is an extension of the Delay and Sum Beamforming technique. These techniques are known to those of skill in the art, and the general concepts are described in “Array Signal Processing: Concepts and Techniques” by Don H Johnson and Dan E Dugeon, published by PTR (ECS Professional) February 1993, ISBN 0-13-048513-6. 
     The DSP  40  receives a steering angle from the iris recognition unit  22  (FIG. 1) as an input on a serial bus  44 . This steering angle is used to access the corresponding algorithm in memory  42  for focusing the acoustic elements to this angle. 
     The DSP  40  has an output bus  46  that conveys digital signals to the loudspeaker array  16 ; and an input bus  48  that receives digital signals from the microphone array  14 ; as will be described in more detail below. 
     The DSP  40  also has a bus  50  for conveying digital signals to a speech recognition unit  52  and a bus  54  for receiving digital signals from a text to speech unit  56 . For clarity, the speech recognition unit  52  and the text to speech unit  56  are shown as functional blocks; however, they are implemented by one or more software modules resident on the ATM controller  20  (FIG.  1 ). 
     Referring now to FIG. 3, the iris recognition unit  22  includes a pair of cameras  60 , 62  for imaging the user  30 , and a locator  64  for locating the position of the user&#39;s eye using the images captured by the cameras  60 , 62 . It will be appreciated that the iris recognition unit  22  contains many more components for capturing an image of the user&#39;s iris and processing the image to obtain an iris template; however, these components are well known and will not be described herein. The locator  64  performs image processing on the captured images to determine the position of the user  30 . This position is output as a steering angle on the serial bus  44  (see also FIG.  2 ). 
     Referring to FIG. 4, which is a block diagram of the linear microphone array  14 , the array  14  comprises twenty microphone elements  70  (only six of which are shown). Each element  70  comprises a microphone transducer  72 , a pre-amplifier  74 , and an analog-to-digital (A/D) converter  76 . Each element  70  outputs a digital signal onto a line  78 . All twenty lines  78  are conveyed to the DSP  40  by the digital input bus  48  (see also FIG.  2 ). 
     Referring to FIG. 5, which is a block diagram of the linear loudspeaker array  16 , the array  16  comprises twenty loudspeaker elements  80  (only six of which are shown). Each element  80  comprises a loudspeaker transducer  82 , a power amplifier  84 , and a digital-to-analog (D/A) converter  86 . Each element  80  receives a digital signal on a line  88 . All twenty lines  88  are coupled to the DSP  40  by the digital output bus  46  (see also FIG.  2 ). 
     Referring to FIG. 6A, a user  30  initiates a transaction by approaching the ATM  10 . The ATM  10  senses the presence of the user  30  in a conventional manner using the iris recognition unit  22 . The cameras  60 , 62  capture images of the user  30  and the locator  64  determines the angular position of the user&#39;s head relative to the iris recognition unit  22 . The locator  64  converts this angular position (the steering angle) to a digital signal and conveys the digital signal to the DSP  40  via serial bus  44 . 
     When the DSP  40  receives this digital representation of the steering angle, the DSP  40  uses this signal to access memory  42  and retrieve the algorithm associated with this angle. The DSP  40  then receives a user command, such as “Please stand still while you are identified”, from the text to speech unit  56 . The user command is received as a digital signal on bus  54 . The DSP  40  then applies the retrieved algorithm to the user command signal, which has the effect of creating twenty different signals, one for each loudspeaker element. Each of these twenty signals is then applied to its respective loudspeaker element  80 . The total sound output from the loudspeaker array  16  is such that only a person located within a privacy zone  90  is able to hear the user command; as the privacy zone  90  is directed to the user&#39;s head, the user has increased privacy. The full zone  92  is the maximum area over which the loudspeakers can transmit (which occurs when the acoustic elements are not focused) and is shown between the broken lines  94 . 
     When the user speaks to the ATM  10 , which may be in response to a user command such as “What transaction would you like to select?”, each microphone element  70  receives the sound from the user  30  and any other ambient sound, such as a passing vehicle, a nearby conversation, and such like. The sound from each microphone element  70  is conveyed to the DSP  40  on input bus  48 . The DSP  40  applies the retrieved algorithm to the signal from each microphone element  70 . In a similar manner to the loudspeaker signals, the algorithm weights and delays each microphone element signal. The DSP  40  then creates a single signal in which the dominant sound is that of a person positioned at the location of the user&#39;s head. The single signal is then conveyed to the speech recognition unit  52  via bus  50 . This greatly improves the accuracy of the speech recognition unit  52  because much of the background noise (from locations other than that of the privacy zone  90 ) is filtered out by the DSP  40 . 
     The iris recognition unit  22  continually monitors the position of the user  30 , so that if the user  30  moves during a transaction, for example from the position shown in FIG. 6A to the position shown in FIG. 6B, then the locator  64  automatically detects the new location of the user  30  and sends the appropriate steering angle to the DSP  40 . The DSP  40  selects the algorithm corresponding to this new steering angle, and the weights and delays associated with this algorithm are used to operate on the acoustic element signals. If the user  30  moves again, for example to the position shown in FIG. 6C, the algorithm is again updated. 
     Referring now to FIG. 7, an ATM  100  includes a microphone linear array  114 , a loudspeaker linear array  116 , an iris detection unit  122  and two proximity sensors  200 . The arrays  114  and  116  are identical to arrays  14  and  16  respectively. In addition, the ATM  100  also has various other ATM modules (none of which is shown in FIG. 7) such as a cash dispenser, a receipt printer, a network connection, and an ATM controller including an array controller. 
     As shown in FIG. 7, a first person  130 a is using the ATM  100 , and two other people  130   b,c  are walking past the ATM  100  in the full zone of transmission of the loudspeaker array  116 . The iris recognition unit  122  detects and locates the position of the first person (the ATM user)  130   a . The proximity detectors  200  detect the presence of the second and third persons  130   b,c.    
     The array controller (not shown) simultaneously uses one algorithm for the speech to text signal to be applied to the loudspeaker array  116 , another algorithm (having coefficients that focus the loudspeaker transmission in a broader zone to one side of the user  130   a ) for operating on a white noise signal for transmission to a first noise zone  196 , and a third algorithm (having coefficients that focus the loudspeaker transmission in a broader zone to the other side of the user  130   a ) for operating on a white noise signal for transmission to a second noise zone  198 . 
     The first and second noise zones correspond to the areas in which the second and third persons  130   b,c  were detected by the proximity detectors  200 . Thus, the user  130   a  can hear the speech from the ATM  100  because the user is located within a privacy zone  190 , but the second and third persons  130   b,c  only hear noise because they are located in noise zones  196 , 198 . 
     Instead of transmitting white noise to one or both of the noise zones  196 , 198 , the array controller may transmit audio advertisements to one or both of these zones. 
     Various modifications may be made to the above described embodiment within the scope of the invention, for example, in other embodiments, the number of loudspeaker elements may be different to the number of microphone elements. 
     In other embodiments, a different algorithm may be used to steer the acoustic elements, for example, adaptive beamforming using the Griffiths-Jim beamformer. In other embodiments, each array may be an array of ultrasonic emitters or transducers that are powered by an ultrasonic amplifier, under control of an ultrasonic signal processor to produce a narrow beam of sound. In other embodiments the locating mechanism may not be an iris recognition unit, but may be a pair of cameras, or other suitable locating mechanism. In embodiments where the position of the user is constrained, for example in drive-up applications where the user aligns the window of his/her vehicle with the microphone and/or loudspeaker array of the drive-up unit, a single camera may be used.