Abstract:
When electric field strength of a reception signal becomes less than a threshold level, an in-vehicle terminal executes one of three operations. The first is that the in-vehicle terminal prohibits input of a voice. The second is that the in-vehicle terminal transmits an inputted voice with a datum indicating radio wave environment to a voice recognition server. The third is that the in-vehicle terminal once stores the inputted voice, and then transmits the inputted voice that has been stored after the electric field strength of the reception signal exceeds the threshold level.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
         [0001]    This application is based on and incorporates herein by reference Japanese Patent Application No. 2002-149147 filed on May 23, 2002.  
         FIELD OF THE INVENTION  
         [0002]    The present invention relates to a voice recognition system, in which an inputted voice is transmitted from a terminal to a server and recognized by the server. In particular, performance of the voice recognition is prevented from lowering even in noisy condition.  
         BACKGROUND OF THE INVENTION  
         [0003]    There is a voice recognition system in which an inputted voice is transmitted from a terminal to a server and recognized by the server.  
           [0004]    For instance, in a vehicle, as a voice of “route search (ráut s∂         t∫)” uttered by a crew is inputted into an in-vehicle terminal, the in-vehicle terminal transmits the inputted voice to a voice recognition server through a phone network. As the voice recognition server receives the voice, it retrieves and computes a route from a current position of a vehicle to a destination. It then transmits a result of retrieving the route to the in-vehicle terminal through the phone network. As the in-vehicle terminal receives the result, it then displays the result. The crew who uttered “route search” is thereby enabled to recognize the route from the current position to the destination.  
           [0005]    Here, the inputted voice is transmitted from the in-vehicle terminal to the voice recognition server through wireless communication. If radio wave environment relating to the wireless communication is deteriorated, quality of the transmitted voice may be lowered (e.g, due to accumulated noise component). This involves high probability of mis-recongnition in the voice recognition server or poor performance of the voice recognition.  
           [0006]    In the vehicle, there are noisy conditions such as a blasting of an air-conditioner, an output of an audio, or operational noise of wipers. According to a state of the vehicle, the above noises become relatively louder than the inputted voice, so that the quality of the transmitted voice is lowered. Furthermore, operation of some in-vehicle devices may adversely affect wireless communication by acting as a signal noise. This also causes the high probability of mis-recognition in the voice recognition server or the poor performance of the voice recognition.  
         SUMMARY OF THE INVENTION  
         [0007]    It is an object of the present invention to provide a terminal, a voice recognition server, and a voice recognition system that is constituted by the terminal and the voice recognition server, the voice recognition system is enabled to prevent mis-recognition and poor performance of the voice recognition. Here, the terminal is for accepting a voice uttered in a vehicle. The voice recognition server is for executing a voice recognition for the voice transmitted from the terminal via wireless communication.  
           [0008]    To achieve the above object, a terminal is provided with the following. It is determined whether radio wave environment relating to the wireless communication or a state of the vehicle meets a condition under which voice recognition can be successfully executed in the voice recognition server. This structure enables the voice recognition system to prevent the mis-recognition, which results in preventing poor performance of the voice recognition.  
           [0009]    In accordance with one aspect of the present invention, inputting of the voice in the terminal is prohibited when it is determined that the radio wave environment or the state of the vehicle does not meet the condition. This structure prevents the voice recognition server from executing unsuccessful voice recognition.  
           [0010]    In accordance with another aspect, the inputted voice is transmitted from the terminal along with a reference datum indicating the radio wave environment or the state of the vehicle when it is determined that the radio wave environment or the state of the vehicle does not meet the condition. This structure enables the voice recognition to properly execute the voice recognition by recognizing the reference datum.  
           [0011]    Furthermore, in accordance with another aspect, the inputted voice is once stored, when it is determined that the radio wave environment does not meet the condition. The stored voice is then transmitted to the voice recognition after it is determined that the radio wave environment meets the condition. This structure enables the voice recognition server to execute the voice recognition for the properly received voice. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]    The above and other objects, features and advantages of the present invention will become more apparent from the following detailed description made with reference to the accompanying drawings. In the drawings:  
         [0013]    [0013]FIG. 1 is a schematic view of a voice recognition system according to an embodiment of the present invention;  
         [0014]    [0014]FIG. 2 is a functional block diagram showing electrical structure of an in-vehicle terminal;  
         [0015]    [0015]FIG. 3 is a functional block diagram showing electrical structure of a voice recognition server;  
         [0016]    FIGS.  4  to  6  are flowchart diagrams explaining processing of a CPU of the in-vehicle terminal;  
         [0017]    [0017]FIGS. 7A, 7B, and  7 C are display window images as examples; and  
         [0018]    [0018]FIG. 8 is a flowchart diagram explaining processing of a CPU of the voice recognition server. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0019]    An embodiment of an in-vehicle terminal to which the present invention is directed will be explained below. In a voice recognition system shown in FIG. 1, an in-vehicle terminal  1  mounted in a vehicle  2  transmits a voice to a voice recognition server  4  through a phone network  3 . The phone network  3  is formed of various phone networks such as a cell phone network, a wired phone network, or the like. As the voice recognition server  4  receives the voice from the in-vehicle terminal  1 , it executes voice recognition for the received voice and then executes processing based on a result from the voice recognition.  
         [0020]    In detail, as a crew in the vehicle  2  utters “route search (ráut s{acute over (∂)}         :t∫),” the in-vehicle terminal  2  transmits a voice of “route search (ráut s{acute over (∂)}:t∫)” to the voice recognition server  4  through the phone network  3 . As the voice recognition server  4  receives the voice, it retrieves and computes a route from a current position of the vehicle  2  to a destination of the vehicle  2  to transmit a result of retrieving to the in-vehicle terminal  1  through the phone network  3 .  
         [0021]    As the in-vehicle terminal  1  receives the result of the retrieving from the voice recognition server  4 , it displays the result. The crew that utters “route search (ráut s{acute over (∂)}:t∫)” can thereby recognize the route from the current position to the destination. In FIG. 1, the route is shown in arrows from the current position of the vehicle  1  shown as “C” to the destination shown in “D.” 
         [0022]    As shown in FIG. 2, the in-vehicle terminal  1  includes the following: a CPU (central processing unit)  5  executing a control program; a microphone  6 ; a speaker  7 ; an acoustic characteristic control  8 ; a voice interface (IF)  9 ; a data interface (IF)  10 ; a multiplexer  11 ; a communication unit  12 ; a storage  13 ; a manipulation unit  14 ; a display  15 ; and a vehicle interface (IF)  16 .  
         [0023]    The microphone  6  is provided in a position of an interior of the vehicle  2 , the position where utterance of the crew of the vehicle  2  is efficiently collected. The microphone  6  outputs the voice inputted by the crew to the acoustic characteristic control  8 . The speaker  7  is provided in a position of the interior of the vehicle  2 , the position where the crew efficiently listens to a voice outputted from the speaker  7 . The speaker  7  externally outputs the voice inputted from the acoustic characteristic control  8 .  
         [0024]    The acoustic characteristic control  8  controls characteristic of the voice inputted from the microphone  6  to output to the voice interface  9 . The acoustic characteristic control  8  controls characteristic of the voice inputted from the voice interface  9  to output to the speaker  7 . The voice interface  9  executes processing for transmission of the voice inputted from the microphone  6  through the acoustic characteristic control  8  to output to the multiplexer  11 . The voice interface  9  executes processing for reception of the voice inputted from the multiplexer  11  to output to the speaker  7  through the acoustic characteristic control  8 . The data interface  10  executes processing for transmission of the data inputted from the CPU  5  to output to the multiplexer  11 . The data interface  10  executes processing for reception of the data inputted from the multiplexer  11  to output to the CPU  5 .  
         [0025]    The multiplexer  11  multiplexes, into a transmission signal, the voice inputted from the voice interface  9  and the data inputted from the data interface  10  to output to the communication unit  12 . The multiplexer  11  extracts, from the multiplexed reception signal from the communication unit  12 , the voice and the data to output to the voice interface  9  and the data interface  10 , respectively. The communication unit  12  transmits, by wireless, the transmission signal inputted from the multiplexer  11 . The communication unit  12  receives, by wireless, a reception signal to output to the multiplexer  11 .  
         [0026]    The storage  13  stores the voice inputted from the microphone  6 . The manipulation unit  14  manipulated by the crew includes several keys (buttons). The manipulation unit  14  can be replaced with keys of touch-panel type provided in the display  15 . The display  15  shows time, guidance information for notifying the crew of warning, information received from the voice recognition server  4  (e.g., map information), or the like.  
         [0027]    The vehicle interface  16  is a device through which operation data indicating operation states of various devices mounted in the vehicle  2  are inputted. The operation data include an air-conditioner operation datum of whether an air-conditioner runs, an audio operation datum of whether an audio runs, and a wipers operation datum of whether the wipers run.  
         [0028]    As shown in FIG. 3, the voice recognition server  4  includes the following: a CPU  17  for executing a control program; a communication unit  18 ; a multiplexer  19 ; a voice interface (IF)  20 ; a data interface (IF)  21 ; and a voice recognition database  22 .  
         [0029]    The communication unit  18  receives, by wireless, a reception signal to output to the multiplexer  19 . The communication unit  18  transmits, by wireless, a transmission signal inputted from the multiplexer  19 . The multiplexer  19  extracts, from the multiplexed reception signal from the communication unit  18 , a voice and data to output to the voice interface  20  and the data interface  21 , respectively. The multiplexer  19  multiplexes, into the transmission signal, a voice inputted from the voice interface  20  and data inputted from the data interface  21  to output to the communication unit  18 .  
         [0030]    The voice interface  20  executes processing for reception of the voice inputted from the multiplexer  19  to output to the CPU  17 . The voice interface  20  executes processing for transmission of the voice inputted from the CPU  17  to output to the multiplexer  19 . The data interface  21  executes processing for reception of the data inputted from the multiplexer  19  to output to the CPU  17 . The data interface  21  executes processing for transmission of the data inputted from the CPU  17  to output to the multiplexer  19 . The voice recognition database  22  stores, as a database, data referred to when the CPU  17  executes voice recognition for the voice inputted from the voice interface  20 .  
         [0031]    Referring to FIGS.  4  to  8 , processing of the above structure will be explained below. The processing is classified into two processings:  
         [0032]    (1) Processing executed by a CPU  5  of an in-vehicle terminal  1   
         [0033]    (2) Processing executed by a CPU  17  of a voice recognition server  4   
         [0034]    The two processings will be explained below in order.  
       (1) Processing Executed by a CPU  5  of an In-Vehicle Terminal  
       [0035]    There are three operation modes of a voice input prohibition mode, a radio wave environment data transmission mode, and a voice storage mode. These three operation modes are selected through manipulating the manipulation unit  14  of the in-vehicle  1  by a user. These three operation modes will be explained in order.  
         [0036]    (1-1) Voice Input Prohibition Mode  
         [0037]    Referring to FIG. 4, at Step  1 , the CPU  5  establishes a wireless communication link between the in-vehicle terminal  1  and the voice recognition server  4  through the communication unit  12 . At Step  2 , a threshold value (TH VALUE) is set for determining whether certain radio wave environment is adequate. The threshold value can be previously determined value or a value that is assumed to be an optimum based on past precedents or use environment.  
         [0038]    At Step  3 , electric field strength (EF STRENGTH) of a reception signal is computed. At Step  4 , the electric field strength is compared with the threshold value.  
         [0039]    When the electric field strength is determined to be not lower than the threshold value, the radio wave environment relating to the wireless communication link between the in-vehicle terminal  1  and the voice recognition server  4  is regarded to be adequate. The CPU  5  thereby awaits a voice input of utterance of a crew in a vehicle  2 . At Step  5 , when the voice of the crew is determined to be uttered, the voice is inputted at Step  6  and transmitted from the communication unit  12  through the phone network  3  to the voice recognition server  4  at Step  7 .  
         [0040]    By contrast, at Step  4 , when the electric field strength is determined to be lower than the threshold value, the radio wave environment relating to the wireless communication link between the in-vehicle terminal  1  and the voice recognition server  4  is regarded to be inadequate. A display guidance such as “INADEQUATE RADIO WAVE ENVIRONMENT! STOP VOICE INPUT!” is shown on the display  15  (in FIG. 7A) at Step  8 . The voice input is thereby prohibited at Step  9 .  
         [0041]    As explained above, under the voice input prohibition mode set in the in-vehicle terminal  1 , when the electric field strength of the reception signal becomes lower than the threshold value, the voice input is thereafter prohibited and any utterance of the crew cannot be inputted.  
         [0042]    At this moment, displaying of the guidance on the display  15  enables the crew to recognize that the voice input is unavailable due to inadequacy of the radio wave environment.  
         [0043]    (1-2) Radio Wave Environment Data Transmission Mode  
         [0044]    Referring to FIG. 5, when the electric field strength of the reception signal is determined to be lower than the threshold value at Step  4 , a display guidance such as “INADEQUATE RADIO WAVE ENVIRONMENT! VOICE INPUT STILL ABAILABLE! INPUTTED VOICE TO BE POSSIBLY MIS-RECOGNIZED!” is shown on the display  15  (in FIG. 7B) at Step  11 .  
         [0045]    At Step  12 , when a voice of the crew is determined to be uttered, the voice is inputted at Step  13 . The CPU  5  obtains electric field strength of a reception signal at the time point as radio wave environment data (RWE DATA) indicating the radio wave environment relating to the wireless communication link between the in-vehicle terminal  1  and the voice recognition server  4  at Step  14 . The CPU  5  then transmits the inputted voice along with the radio wave environment data from the communication unit  12  through a phone network  3  to the voice recognition server  4  at Step  15 .  
         [0046]    As explained above, under the radio wave environment data transmission mode set in the in-vehicle terminal  1 , when the electric field strength of the reception signal becomes lower than the threshold value, the inputted voice is thereafter transmitted with the radio wave environment data to the voice recognition server  4 .  
         [0047]    At this moment, displaying of the guidance on the display  15  enables the crew to recognize the possibility that the inputted voice is mis-recongized in the voice recognition server  4  due to inadequacy of the radio wave environment.  
         [0048]    (1-3) Voice Storage Mode  
         [0049]    Referring to FIG. 6, when the electric field strength of the reception signal is determined to be lower than the threshold value at Step  4 , a display guidance such as “INADEQUATE RADIO WAVE ENVIRONMENT! VOICE INPUT STILL ABAILABLE! INPUTTED VOICE TO BE LATER SENT TO SERVER!” is shown on the display  15  (in FIG. 7C) at Step  21 .  
         [0050]    At Step  22 , when a voice of the crew is determined to be uttered, the voice is inputted at Step  23 . The CPU  5  then stores the inputted voice in the storage  13  at Step  24 .  
         [0051]    At Step  25 , electric field strength of a reception signal at the time point is again compared with the threshold value. When the electric field strength is determined to be not lower than the threshold value, the radio wave environment relating to the wireless communication link between the in-vehicle terminal  1  and the voice recognition server  4  is regarded to be adequate. At Step  26 , the CPU  5  then obtains elapse data indicating elapsed time from the time when voice is stored in the storage  13 . At Step  27 , the inputted voice stored in the storage  13  with the elapse data is transmitted to the voice recognition server  4 .  
         [0052]    As explained above, under the voice storage mode set in the in-vehicle terminal  1 , when the electric field strength of the reception signal becomes lower than the threshold value, the voice inputted by utterance of the crew is stored. When the electric field strength of the reception signal becomes not lower than the threshold value, the stored inputted voice is transmitted with the elapse data to the voice recognition server  4 .  
         [0053]    At this moment, displaying of the guidance on the display  15  enables the crew to recognize that the inputted voice is once stored due to inadequate radio wave environment and to be transmitted to the voice recognition server  4  when the radio wave environment returns to an adequate state.  
       (2) Processing Executed by a CPU  17  of a Voice Recognition Server  4   
       [0054]    Referring to FIG. 8, at Step  101 , the CPU  17  establishes a wireless communication link between the in-vehicle terminal  1  and the voice recognition server  4  through the communication unit  18 . At Step  102 , a reject threshold value (REJECT TH VALUE) for the radio wave environment is set. At Step  103 , a reject threshold value (REJECT TH VALUE) for certain elapsed time is set. Each of the above reject threshold values can be previously determined value or a value that is assumed to be an optimum based on past precedents or use environment.  
         [0055]    At Step  104 , the voice is received from the in-vehicle terminal  1  through the communication unit  18 . At Step  105 , whether the received voice is accompanied with the radio wave environment data or the elapse data is determined. When the received voice is determined to be accompanied with no radio wave environment data and no elapse data, the CPU  17  executes voice recognition by referring to the voice recognition database  22  at Step  107 . A result of the voice recognition is transmitted to the in-vehicle terminal  1  through the communication unit  18  and the phone network  3  at Step  108 .  
         [0056]    As explained above, when the voice recognition server  4  receives the voice without any accompanying radio wave environment data or elapse data, the voice recognition server  4  executes the voice recognition to transmit the result of the voice recognition to the in-vehicle terminal  1 . Here, no accompanying data to the received voice indicates that radio wave environment is adequate for computing the voice recognition.  
         [0057]    By contrast, when the received voice is determined to be accompanied with the radio wave environment data, the radio wave environment data are analyzed at Step  109 . The electric field strength indicated in the radio wave environment data is then compared with the reject threshold value for the radio wave environment at Step  110 .  
         [0058]    When the electric field strength is determined to be not lower than the reject threshold value, the voice recognition is executed by referring to the voice recognition database  22  at Step  111 . Here, the voice recognition is executed especially by enhancing voice recognition level for the received voice. A result of the voice recognition is then transmitted to the in-vehicle terminal  1  through the communication unit  18  and the phone network  3  at Step  112 .  
         [0059]    When the electric field strength is determined to be lower than the reject threshold value, the voice recognition for the voice received from the in-vehicle terminal  1  is rejected and a reject notice signal indicating of rejection of the voice recognition is transmitted to the in-vehicle terminal  1  through the communication unit  18  and the phone network  3  at Step  113 .  
         [0060]    As explained above, when the voice recognition server  4  receives the voice with the accompanying radio wave environment data, the voice recognition server  4  executes the voice recognition only when the electric field strength is determined to be not lower than the reject threshold value. The result of the voice recognition is then transmitted to the in-vehicle terminal  1 . Here, the radio wave environment data accompanying the received voice indicates that the received voice is inputted under the inadequate radio wave environment.  
         [0061]    When the received voice is determined to be accompanied with the elapse data, the elapse data are analyzed at Step  114 . The elapsed time indicated in the elapse data is then compared with the reject threshold value for the elapsed time at Step  115 .  
         [0062]    When the elapsed time is determined to be not greater than the reject threshold value, the voice recognition is executed by referring to the voice recognition database  22  at Step  116 . A result of the voice recognition is then transmitted to the in-vehicle terminal  1  through the communication unit  18  and the phone network  3  at Step  117 .  
         [0063]    When the elapsed time is determined to be greater than the reject threshold value, the voice recognition for the voice received from the in-vehicle terminal  1  is rejected. Here, voice recognition after elapsed time greater than the reject threshold value is assumed to be no more useful for the crew due to too late feedback. A reject notice signal indicating of rejection of the voice recognition is then transmitted to the in-vehicle terminal  1  through the communication unit  18  and the phone network  3  at Step  118 .  
         [0064]    Thus each of the CPU  5  of the in-vehicle terminal  1  and the CPU  17  of the voice recognition server  4  executes the processing in correspondence to the radio wave environment relating to the wireless communication.  
         [0065]    According to the above embodiment, under the voice input prohibition mode set in the in-vehicle terminal  1 , when the electric field strength of the reception signal becomes lower than the threshold value, the voice input is prohibited and any utterance of the crew cannot be inputted. The voice recognition server  4  thereby receives no voice and executes no voice recognition, so that mis-recogniton of the voice recognition is prevented from occurring. This results in preventing poor performance of the voice recognition from occurring.  
         [0066]    In addition, under the radio wave environment data transmission mode set in the in-vehicle terminal  1 , when the electric field strength of the reception signal becomes lower than the threshold value, the inputted voice is transmitted with the radio wave environment data to the voice recognition server  4 . The voice recognition server  4  thereby recognizes that the received voice is inputted under the inadequate radio wave environment. Hence, the voice recognition is executed with considering the situation, for instance, by enhancing recognition level, so that mis-recogniton of the voice recognition is prevented from occurring. This results in preventing poor performance of the voice recognition from occurring.  
         [0067]    Furthermore, under the voice storage mode set in the in-vehicle terminal  1 , when the electric field strength of the reception signal becomes lower than the threshold value, the voice inputted by utterance of the crew is stored. When the electric field strength of the reception signal becomes not lower than the threshold value, the stored inputted voice is transmitted with the elapse data to the voice recognition server  4 . The voice recognition server  4  thereby receives the temporarily stored voice under the adequate radio wave environment instead of the inadequate radio wave environment, so that mis-recogniton of the voice recognition is prevented from occurring. This results in preventing poor performance of the voice recognition from occurring.  
       Modification  
       [0068]    The embodiment can be modified below.  
         [0069]    Although the invention is directed to an in-vehicle terminal, it can be directed to a terminal which a person carries. Moreover, an in-vehicle terminal can be fixed as an assembled module or detachable from a vehicle.  
         [0070]    Although display guidance indicating radio wave environment or vehicle state is shown on a display of a vehicle, by adopting a voice output function voice guidance indicating the radio wave environment or the vehicle state can be outputted through a speaker. The voice guidance can be used along with the display guidance.  
         [0071]    The reject threshold value for the radio wave environment or the elapsed time can be set in the voice recognition server according to need.  
         [0072]    A control program executed by a CPU of each of an in-vehicle terminal and a voice recognition server can be not only stored at a manufacturing stage, but also downloadable through a network from a certain server or installed by being forwarded from storage media such as CD-DOM (compact disk-read only memory) or other card memories.