Patent Document

CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application is related to and claims priority under 35 U.S.C. §119 to European Application No. 13157131.7, filed 28 Feb. 2013, the entirety of which is hereby incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to a system for enabling a visually impaired or blind person to use an input device having at least one key. 
       BACKGROUND 
       [0003]    As is known, electronic devices, for example PCs, DVD players, mobile phones, laptops etc., usually comprise a keyboard as an input device. The input device has dimensions and structures particularly arranged to be used by people having no visual problems. 
         [0004]    Such input devices of a generic electronic device are not arranged to be used by visually impaired or blind people, because blind people do not have any reference on the keys in order to know which key are going to press. Even keyboards particularly arranged to be used by blinds have the following draw backs: First they need a special keyboard type (depends on Braille techniques, as for an example described in U.S. Pat. No. 7,706,509 B2) as an input device. Second, such keyboards increase the costs of for example a regular PC to be suitable for blind people usage. Also, there are further problems with respect to portability. 
         [0005]    Similar problems arise for example with respect to all types of remote control devices that as used herein shall also be considered as input devices. 
         [0006]    Further approaches comprise special keyboards with less keys, screen readers as well as speech recognition hardware and software. 
       SUMMARY 
       [0007]    It is therefore an object of this invention to provide a system for enabling visually impaired or blind persons to use an input device having at least on key, like for example a keyboard or a remote control device, and in particular an input device that is similar to a corresponding input device for people that are not visually impaired or blind or can be achieved from a regular input device by only little modification. 
         [0008]    This object is accomplished according to the present invention by a system for enabling a visually impaired or blind person to use an input device having at least one key, comprising: at least one tactile sensor array, in particular a pressure sensor array, attachable to a fingertip of a visually impaired or blind person for acquiring a pressure distribution image of a key slightly touched by a finger of said person when attached to said finger, a pressure distribution image processing and character recognition unit that is connected to said tactile sensor array for processing said pressure distribution image and for recognizing the key label of the touched key and an audio output device that is connected to said unit for outputting an acoustic reproduction of said key label. The key label could be for example a character, symbol, figure/number, arrow key/courser key etc. Relief-like could mean for example protruding or raised, like a raised structure. The relief-like key labels could be considered as tactile labels for tactile representation of information. So a part of the system could be considered as a system part for recognition of the key labels. The pressure distribution image processing and character recognition unit can comprise to sub-units, one for pressure distribution image processing and one for character recognition that could be physically separated. 
         [0009]    Preferably, the system further comprises an input device having at least one key, wherein the at least one key is provided with a relief-like key label. 
         [0010]    According to a special embodiment of the invention, the input device is a keyboard or a remote control device. 
         [0011]    The relief-like key label could be integral with the key. 
         [0012]    Alternatively, the relief-key label could be part of a sticker that is attached to the key, e.g. by way of pasting. In other words, regular keys could be used in combination with stickers. 
         [0013]    Preferably the system comprises at least two tactile sensor arrays attachable to a fingertip of a visually impaired or blind person. For example the tactile sensor arrays could be attached to a fingertip of the thumb and of the index finger. 
         [0014]    According to a special embodiment, the tactile sensor array(s) is/are part of a glove. 
         [0015]    Conveniently the pressure distribution image processing and character recognition unit is wrist or arm mountable, i.e. mountable to a wrist or arm of the visually impaired or blind person. 
         [0016]    Preferably, the audio output device is wrist or arm mountable, i.e. mountable to a wrist or arm of the visually impaired or blind person. 
         [0017]    Finally, according to a special embodiment, the audio output device is a loudspeaker, in particular a loudspeaker that is incorporated in a device to which the input device belongs. For example, if the input device is a keyboard of a laptop or mobile phone, the audio output could be the loudspeaker of the laptop or the mobile phone. 
         [0018]    The invention is based on the surprising knowledge that by way of at least one tactile sensor array an “image” of a key label can be captured and converted into a corresponding audio representation. By this visually impaired or blind persons can interact with regular input devices, in particular keyboards and remote control devices, or slightly amended (regular) input devices, in particular keyboards and remote control devices. 
         [0019]    Furthermore, at least in a particular embodiment, most of the components of the system are portable. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    Further features and advantages of the invention will become clear from the enclosed claims and the following description, in which a number of embodiments of the invention are illustrated in detail with reference to this geometrics drawings, wherein: 
           [0021]      FIG. 1  shows a view of a system for enabling a visually impaired or blind person to use an input device having at least one key according to a special embodiment of the invention attached to the hand of such a person; 
           [0022]      FIG. 2  shows a top view of a key board, wherein prominent (3D) stickers are pasted to the letters E and R, respectively; 
           [0023]      FIG. 3  shows a pressure distribution image as captured by a pressure sensor array of the letter R while being slightly touched; 
           [0024]      FIG. 4  shows a block diagram of the system of  FIG. 1 ; 
           [0025]      FIG. 5  shows a flow diagram of an algorithm for simplified character recognition; and 
           [0026]      FIG. 6  shows keys with key labels of a remote control device or different remote control devices. 
       
    
    
     DETAILED DESCRIPTION 
       [0027]    The system  10  of  FIG. 1  comprises two pressure sensor arrays  12  and  14 . The pressure sensor array  12  is arranged at a fingertip of the thumb, whereas the pressure sensor array  14  is arranged at the fingertip of the index finger of a hand  15  of a visually impaired or blind person (not shown). Said pressure sensor arrays  12  and  14  could be attached to the fingertips by way of finger cots. 
         [0028]    Furthermore, the system  10  comprises a pressure distribution image processing and character recognition unit  16  that will be described in detail with reference to  FIG. 4  below. The pressure sensor arrays  12  and  14  are electrically connected to the pressure distribution image processing and character recognition unit  16  by way of cables  18  and  20 , respectively. 
         [0029]    Also, the system  10  comprises a loudspeaker  22  that is incorporated in the same housing  24  as the character recognition unit  16 . Said housing  24  is attached to a kind of wristband  26  that is attached to the wrist  28 . 
         [0030]    In the present special embodiment, the pressure sensor arrays  12  and  14  each consists of an array of 64 sensor elements distributed in eight rows and eight columns. Each sensor element is 2 mm×2 mm in size, so that the size of the total sensor array is 16 mm×16 mm. The pressure sensor arrays  12  and  14  are highly sensitive capacitive-based pressure sensors. They reliably quantify the pressure distribution under the slightly touched area. In particular, they are practical, user-configurable and comfortable. The pressure sensor arrays  12  and  14  are arranged in the respective areas that usually contact the keys of for example a keyboard. 
         [0031]      FIG. 2  shows a keyboard  30 . It is a regular keyboard that is adjusted through pasting a prominent three dimensional (3D) sticker on each of the key board keys. For reasons of simplicity, only the keys “E” and “R” are shown with pasted stickers with relief-like labeling. Once a visually impaired or blind person touches for example the key with the relief-like label “R” with the pressure sensor arrays  12  or  14  of  FIG. 1 , he/she can hear the key label/value instead of sensing it only. This task is achieved through acquiring a pressure distribution image  31  (for example gray scale image) of the slightly touched prominent key area as shown in  FIG. 3  and by carrying out character recognition by means of the pressure distribution image processing and character recognition unit  16 . A character recognition algorithm as shown in  FIG. 5  helps to extract the key label/value and to convert it into sound that the person can hear via the loudspeaker  22 . So in the present special embodiment any regular PC-keyboard, prepared with stickers, can be used by a visually impaired or blind person as an input device. 
         [0032]    If it is the proper key which the person is looking for, he/she can take the decision of the actual use of the key. 
         [0033]    In  FIG. 4 , only one, namely pressure sensor array  12 , is shown. It should be clear that the pressure sensor array  14  would be connected in a similar way. As can be seen in  FIG. 4 , the 64 analog signal output from the pressure sensor array  12  is input into a powerful Psoc mixed signal microcontroller  32 . Said microcontroller  32  comprises a differential analog multiplexer (MUX)  34 , a signal conditioner  36 , a 8-bit-ADC  38 , a DSP  40 , a DC offset compensator  42 , an uSD-reader  44  and a 8-bit-DAC  46 . The sensor signals pass through the MUX  34 , then the signal conditioner  36  that conditions (amplification (for example PGA), filtering (for example LPF), DC offset by DC offset compensator  42 ) the signals, thereafter the ADC  38  for digitization to get grey level images (64 bytes) of the slightly touched area (see  FIG. 3 ). The pressure distribution image is further processed to extract the touched key label/value by the DSP (40 character recognition). Furthermore, the Psoc microcontroller  32  reads a sound file stored in external uSD-memory in the uSD-reader  44 . The read sound file corresponds to the recognized key label/value. The Psoc microcontroller  32  then sends this sound file to an external audio amplifier  48  such that the person can hear the touched key label via the loudspeaker  22 . As can be seen in  FIG. 4 , the components of the system that are attached to the hand of the person are powered by a battery  50 . 
         [0034]    The following specification and parameters are merely illustrative: 
         [0035]    MUX  34 : High impedance input, input signals rail-to-rail. Configurable number of inputs up to 64X1. 
         [0036]    Signal conditioner  36 : PGA: (Programmable gain) amplifier: Differential “High impedance input, wide bandwidth” low offset output voltage and up to thirty-three user-programmable gain settings with a maximal gain of 48.0″.
       LPF (low path filter): Programmable corner frequency and damping ratio with no external components, second order.       
 
         [0038]    ADC  38 : 8-bit resolution, differential input, unsigned data format, sample rate up to 15.6 ksps and input range defined by Psoc internal reference. 
         [0039]    DSP (Digital signal processing)  40 : Character recognition algorithms allow the system to automatically recognize touched key labels etc. (see  FIG. 5 ). 
         [0040]    uSD-Reader  44 : This module interfaces to an external uSD memory card. Said memory card has a stored group of sound files. Each sound file is corresponding to one of the key label/value/character of the keyboard. When a new key label/value/character is recognized, the uSD-reader  44  reads the external uSD memory card for the corresponding sound file. Further, it sends said sound file to the DAC  46 . The output of the DAC  46  is passed to the external audio amplifier  48  such that the person can hear the touched key label/value/character via the loudspeaker  22 . 
         [0041]    DAC  46 : 8-bit resolution, voltage output, 2&#39;s complement, offset binary and sign/magnitude input data formats, sample and hold for analog bus and external outputs, high update rates. 
         [0042]    Audio Amplifier  48 : Low voltage, low power dissipation, wide gain range from 20 to 200, battery operation. 
         [0043]    Battery  50 : 3.6 volt, 1800 mA would be a suitable battery selection. 
         [0044]      FIG. 5  shows a possible way of character recognition. Each of the pressure sensor arrays  12  and  14  input a pressure distribution image. Each of said pressure distribution images is pre-processed for conditioning the pressure distribution image. Each image has a size of 64 pixels. Each pixel is specified by only black, white and shades of gray. This requires only one byte to save each pixel value. 
         [0045]    The steps included in the pre-processing are: 
         [0046]    Dilation: Operation by which missing pixels from the binary image are filled, 
         [0047]    Erosion: Operation by which extra pixels from the binary image are removed and the character is thinned. 
         [0048]    In the feature extraction following the pre-processing various features are extracted like:
       Number of end points   Angel made by the end points with horizontal   Cross joint   Euclidian distance   Eccentricity   Area   Centroid       
 
         [0056]    Thereafter character recognition is carried out by a comparison of the extracted features with the stored character features in a database of characters or labels. According to matched features the respective character/value/label is known. 
         [0057]      FIG. 6  shows the keyboard  52  or a number of keys of a remote control device, in particular a media player remote control device. It comprises among others a play key  54  and a stop key  56 . When the keys have prominent key labels for example by way of prominent stickers on the regular keys, the keyboard can be used by a visually impaired or blind person with the system as shown in  FIG. 1 . 
         [0058]    The features in the foregoing description, in the claims and/or in the accompanying drawings may, both and in any combination thereof, be material for realising the invention in diverse forms thereof. 
       LIST OF REFERENCE NUMBERS 
       [0000]    
       
         
           
               10  system 
               12 ,  14  pressure sensor arrays 
               15  hand 
               16  pressure distribution image processing and character recognition unit 
               18 ,  20  cables 
               22  loudspeaker 
               24  housing 
               26  wristband 
               28  wrist 
               30  keyboard 
               31  pressure distribution image 
               32  Psoc microcontroller 
               34  MUX 
               36  signal conditioner 
               38  ADC 
               40  DSP 
               42  DC offset compensator 
               44  uSD-reader 
               46  DAC 
               48  audio amplifier 
               50  battery 
               52  keyboard 
               54  play key 
               56  stop key

Technology Category: g