Patent Publication Number: US-8116488-B2

Title: Sound reproducing apparatus and vehicle using the sound reproducing apparatus

Description:
This application is a U.S. National Phase Application of PCT International Application PCT/JP2006/307311. 
     TECHNICAL FIELD 
     The present invention relates to a sound reproducing apparatus and a vehicle using the sound reproducing apparatus. 
     BACKGROUND ART 
     Conventionally, a sound reproducing apparatus and a vehicle using the same are as shown in  FIG. 9 . 
     In  FIG. 9 , phase shifter  2  is connected to music signal source  1 , and the signal from music signal source  1  is phase-shifted by phase shifter  2 . Power amplifier  3  is connected to phase shifter  2 , and the output signal from phase shifter  2  is amplified by power amplifier  3 . Output unit  4 A is connected to power amplifier  3 , and music or the like is outputted from output unit  4 A. Power amplifier  5  is also connected to music signal source  1 , and the output signal from music signal source  1  is amplified by power amplifier  5 . Output unit  5  is connected to power amplifier  6 A, and music or the like is outputted from output unit  6 A. 
     As document information of prior art regarding this application, for example, Japanese Laid-Open Patent 2003-47097 is commonly known. 
     However, such a conventional sound reproducing apparatus involves a problem of sound quality. 
     That is, in the above conventional configuration, it is supposedly possible to prevent a specific frequency entering the right and left ears of the listener in vehicle  7  from being reversed in phase and muted. However, as shown in  FIG. 9 , when output unit  4 B and output unit  6 B are disposed at the rear seat side, sound wave interference that occurs in the front and rear direction of vehicle  7  cannot be prevented. Accordingly, it results in, for example, worsening of gain characteristic near 100 Hz at the rear seat. 
     DISCLOSURE OF THE INVENTION 
     A sound reproducing apparatus, comprising a sound signal source, a first power amplifier connected to the sound signal source, a first output unit connected to the first power amplifier, a first phase shifter connected to the sound signal source, a second power amplifier connected to the first phase shifter, a second output unit connected to the second power amplifier, a second phase shifter connected to the sound signal source, a third power amplifier connected to the second phase shifter, a third output unit connected to the third power amplifier, a third phase shifter connected to the sound signal source, a fourth phase shifter connected to the third phase shifter, a fourth power amplifier connected to the fourth phase shifter, and a fourth output unit connected to the fourth power amplifier, wherein the first output unit and the second output unit are in right and left relation with each other, the third output unit and the fourth output unit are in right and left relation with each other, and the group of the first output unit and second output unit and the group of the third output unit and fourth output unit are in front and back relation with each other. 
     A vehicle, comprising the sound reproducing apparatus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a block diagram of a sound reproducing apparatus and a vehicle using the sound reproducing apparatus in the preferred embodiment 1 of the present invention. 
         FIG. 2  is a block diagram of another sound reproducing apparatus and a vehicle using the sound reproducing apparatus in the preferred embodiment 1 of the present invention. 
         FIG. 3  is a block diagram of still another sound reproducing apparatus and a vehicle using the sound reproducing apparatus in the preferred embodiment 1 of the present invention. 
         FIG. 4  is a block diagram of a sound reproducing apparatus and a vehicle using the sound reproducing apparatus in the preferred embodiment 2 of the present invention. 
         FIG. 5  is a block diagram of another sound reproducing apparatus and a vehicle using the sound reproducing apparatus in the preferred embodiment 2 of the present invention. 
         FIG. 6  is a block diagram of still another sound reproducing apparatus and a vehicle using the sound reproducing apparatus in the preferred embodiment 2 of the present invention. 
         FIG. 7  is a block diagram of further another sound reproducing apparatus and a vehicle using the sound reproducing apparatus in the preferred embodiment 2 of the present invention. 
         FIG. 8  is a block diagram of further another sound reproducing apparatus and a vehicle using the sound reproducing apparatus in the preferred embodiment 2 of the present invention. 
         FIG. 9  is a configuration diagram showing a conventional sound reproducing apparatus and a vehicle using the sound reproducing apparatus. 
     
    
    
     DESCRIPTION OF THE REFERENCE NUMERALS AND SIGNS 
     
         
           8  Signal source 
           9 A,  9 AB First power amplifier 
           9 B,  9 BB Second power amplifier 
           9 C,  9 DB Third power amplifier 
           9 D,  9 CB Fourth power amplifier 
           9 AA Fifth power amplifier 
           9 BA Sixth power amplifier 
           9 CA Seventh power amplifier 
           9 DA Eighth power amplifier 
           10 A,  10 AB First output unit 
           10 B,  10 BB Second output unit 
           10 AA Fifth output unit 
           10 BA Sixth output unit 
           11 A First phase shifter 
           11 B Third phase shifter 
           11 C Fifth phase shifter 
           11 D Sixth phase shifter 
           12 A,  12 B,  18 A,  18 B,  18 C,  18 D,  12 AA,  12 BA Unit 
           13  Vehicle 
           14 A,  14 BA Second phase shifter 
           14 B,  14 AA Fourth phase shifter 
           14 C Seventh phase shifter 
           14 D Eighth phase shifter 
           15 A,  15 AB Third output unit 
           15 B,  15 BB Fourth output unit 
           15 BA Seventh output unit 
           15 AA Eighth output unit 
           16 A Third filter 
           16 B Fourth filter 
           16 C Seventh filter 
           16 D Eighth filter 
           17 A First filter 
           17 B Second filter 
           17 C Fifth filter 
           17 D Sixth filter 
           19 A Ninth phase shifter 
           19 B Tenth phase shifter 
           19 C Eleventh phase shifter 
           19 D Twelfth phase shifter 
           20 A,  20 B,  20 C,  20 D Delay filter 
       
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The object of the present invention is to improve the sound quality in a sound reproducing apparatus and a vehicle equipped with the sound reproducing apparatus. 
     The sound reproducing apparatus of the present invention has two pairs of output units in front and rear which are given phase difference existing between the right and the left, and the two pairs of output units are further given phase difference. In this way, it is possible to reduce the worsening of gain characteristic due to sound wave interference that occurs in the front and rear direction of the vehicle. Accordingly, it brings about an effect of improving the sound quality. 
     Preferred Embodiment 1 
     A sound reproducing apparatus and a vehicle using the sound reproducing apparatus in the preferred embodiment 1 of the present invention will be described in the following with reference to the drawings. 
     In the block diagram of  FIG. 1 , at the front seat side of vehicle  13 , first power amplifier  9 A is connected to signal source  8 . First output unit  10 A is connected to the first power amplifier  9 A. Signal source  8  in the present invention is not limited to music. Also, vehicle  13  is for example an automobile, but the present invention is not limited to automobile. The signal outputted from signal source  8  is amplified by first power amplifier  9 A and outputted from first output unit  10 A. Also, first phase shifter  11 A is connected to signal source  8 . Second power amplifier  9 B is connected to the first phase shifter  11 A. Second output unit  10 B is connected to the second power amplifier  9 B. The signal outputted from signal source  8  is phase-shifted at first phase shifter  11 A. The phase-shifted signal is amplified by second power amplifier  9 B and outputted from second output unit  10 B. 
     Unit  12 A comprises the signal source  8 , first power amplifier  9 A, first output unit  10 A, first phase shifter  11 A, second power amplifier  9 B, and second output unit  10 B. In vehicle  13 , the first output unit  10 A and second output unit  10 B are in right and left relation with each other, and the output from second output unit  10 B is controlled by first phase shifter  11 A. In this way, it is possible to reduce the worsening of sound quality due to sound wave interference that occurs in the right and left direction from first output unit  10 A to second output unit  10 B. 
     On the other hand, at the rear seat side of vehicle  13 , second phase shifter  14 A is connected to signal source  8 , third power amplifier  9 C is connected to the second phase shifter  14 A, and third output unit  15 A is connected to the third power amplifier  9 C. The signal outputted from signal source  8  is phase-shifted by second phase-shifter  14 A. The phase-shifted signal is amplified by third power amplifier  9 C and outputted from third output unit  15 A. Also, third phase shifter  11 B is connected to signal source  8 . Fourth phase shifter  14 B is connected to third phase shifter  11 B. Fourth power amplifier  9 D is connected to the fourth phase shifter  14 B. Fourth output unit  15 B is connected to the fourth power amplifier  9 D. The signal from signal source  8  is phase-shifted by third phase shifter  11 B. The signal phase-shifted by third phase shifter  11 B is further phase-shifted by fourth phase shifter  14 B. The signal further phase-shifted by fourth phase shifter  14 B is amplified by fourth poser amplifier  9 D and outputted from fourth output unit  15 B. 
     Unit  12 B comprises the signal source  8 , second phase shifter  14 A, third power amplifier  9 C, third output unit  15 A, third phase shifter  11 B, fourth phase shifter  14 B, fourth power amplifier  9 D, and fourth output unit  15 B. In vehicle  13 , the third output unit  15 A and fourth output unit  15 B are in right and left relation with each other. The output from fourth output unit  15 B is phase-controlled by third phase shifter  11 B, and thereby, it is possible to reduce the worsening of sound quality due to sound wave interference that occurs in the right and left direction from third output unit  15 A to fourth output unit  15 B. 
     Further, in the configuration having unit  12 A and unit  12 B, a group of first output unit  10 A and second output unit  10 B in vehicle  13  and a group of third output unit  15 A and fourth output unit  15 B are in front and rear relation with each other. The outputs from third output unit  15 A and fourth output unit  15 B are respectively phase-controlled by second phase shifter  14 A and fourth phase shifter  14 B, and thereby, it is possible to reduce the worsening of sound quality due to sound wave interference that occurs in the front and rear direction of the vehicle. 
     As the phase shifter  11 A, third phase shifter  11 B, second phase shifter  14 A, and fourth phase shifter  14 B, for example, secondary phase shifters are used. Similar effects can be obtained by using those of secondary or higher order. 
     It is preferable to reverse the order in which third phase shifter  11 B and fourth phase shifter  14 B are connected. 
     Also, in this preferred embodiment, fourth phase shifter  14 B is connected to third phase shifter  11 B. However, it is preferable to connect the fourth phase shifter  14 B to first phase shifter  11 A, eliminating third phase shifter  11 B. 
       FIG. 2  shows another example of configuration in this preferred embodiment. In the configuration of  FIG. 2 , fifth phase shifter  11 C and sixth phase shifter  11 D are added to the configuration of  FIG. 1 .  FIG. 2  is explained in the following mainly about the differences from  FIG. 1 . As shown in  FIG. 2 , fifth phase shifter  11 C different in phase rotation center frequency from first phase shifter  11 A is disposed between signal source  8  and first power amplifier  9 A. Also, sixth phase shifter  11 D different in phase rotation center frequency from third phase shifter  11 B is disposed between signal source  8  and third power amplifier  9 C. In this way, sound quality deterioration due to sound wave interference that occurs in the right and left direction of vehicle  13  can be reduced over a broad band between first output unit  10 A and second output unit  10 B, and between third output unit  15 A and fourth output unit  15 B. 
     It is preferable to reverse the order in which sixth phase shifter  11 D and second phase shifter  14 A are connected. 
       FIG. 3  shows further another example of configuration in this preferred embodiment. In the configuration of  FIG. 3 , seventh phase shifter  14 C and eighth phase shifter  14 D are added to the configuration of  FIG. 2 .  FIG. 3  is explained in the following mainly about the differences from  FIG. 2 . As shown in  FIG. 3 , seventh phase shifter  14 C different in phase rotation center frequency from second phase shifter  14 A is disposed between signal source  8  and first power amplifier  9 A. Also, eighth phase shifter  14 D different in phase rotation center frequency from fourth phase shifter  14 B is disposed between signal source  8  and second power amplifier  9 B. In this way, sound quality deterioration due to sound wave interference that occurs in the front and rear direction of vehicle  13  can be reduced over a broad band. 
     The preferred embodiment 1 of the present invention has been described above with reference to the drawings. In this preferred embodiment, there is provided a controller (not shown) for controlling the characteristic of each phase shifter and the characteristic of each filter, and it is possible to control each phase shifter and filter to the desired characteristic by means of the controller. As a result of this control, the sound quality can be further optimized or the sound quality can be freely adjusted according to the listener&#39;s liking. The controller can be installed so as to be operated by the driver of vehicle  13 , and it can also be installed so as to be operated by the person at each seat of the vehicle. 
     Preferred Embodiment 2 
     A sound reproducing apparatus and a vehicle using the sound reproducing apparatus in the preferred embodiment 2 of the present invention will be described in the following with reference to the drawings. 
     Those having same configuration as that of the preferred embodiment 1 are given same reference numerals and the description is omitted. 
       FIG. 4  shows a sound reproducing apparatus and a vehicle using the sound reproducing apparatus in the preferred embodiment 2. In the block diagram of  FIG. 2 , third filter  16 A and first filter  17 A are connected to signal source  8 . Fifth power amplifier  9 AA is connected to third filter  16 A, and fifth output unit  10 AA is connected to fifth power amplifier  9 AA. First power amplifier  9 AB is connected to first filter  17 A, and first output unit  10 AB is connected to first power amplifier  9 AB. 
     First filter  17 A is for example a low-pass filter, and third filter  16 A is for example a high-pass filter. When first filter  17 A is a low-pass filter, and third filter  16 A is a high-pass filter, then the signal from signal source  8  is attenuated for low-pass frequency component by third filter  16 A, and high-pass frequency component is supplied to fifth power amplifier  9 AA. On the other hand, the signal from signal source  8  is attenuated for high-pass frequency component by first filter  17 A, and low-pass frequency component is supplied to first power amplifier  9 AB. The cut-off frequency of first filter  17 A and the cut-off frequency of third filter  16 A are for example set to nearly same frequency. 
     Unit  18 A comprises signal source  8 , third filter  16 A, first filter  17 A, fifth power amplifier  9 AA, fifth output unit  10 AA, first power amplifier  9 AB, and first output unit  10 AB. 
     Also, fourth filter  16 B and second filter  17 B are connected to signal source  8 . Sixth power amplifier  9 BA is connected to fourth filter  16 B, and sixth output unit  10 BA is connected to sixth power amplifier  9 BA. First phase shifter  11 A is connected to second filter  17 B, second power amplifier  9 BB is connected to first phase shifter  11 A, and second output unit  10 BB is connected to second power amplifier  9 BB. 
     Second filter  17 B is for example a low-pass filter, and fourth filter  16 B is for example a high-pass filter. When second filter  17 B is a low-pass filter, and fourth filter  16 B is a high-pass filter, then the signal from signal source  8  is attenuated for low-pass frequency component by fourth filter  16 B, and high-pass frequency component is supplied to sixth power amplifier  9 BA. On the other hand, the signal from signal source  8  is attenuated for high-pass frequency component by second filter  17 B, and low-pass frequency component is supplied to first phase shifter  11 A. The cut-off frequency of fourth filter  16 B and the cut-off frequency of second filter  17 B are for example set to nearly same frequency. 
     Unit  18 B comprises signal source  8 , fourth filter  16 B, second filter  17 B, sixth power amplifier  9 BA, sixth output unit  10 BA, first phase shifter  11 A, second power amplifier  9 BB, and second output unit  10 BB. 
     Further, seventh filter  16 C and fifth filter  17 C are connected to signal source  8 . Seventh power amplifier  9 CA is connected to seventh filter  16 C, and seventh output unit  15 BA is connected to seventh power amplifier  9 CA. Third phase shifter  11 B is connected to fifth filter  17 C, and fourth phase shifter  14 AA is connected to third phase shifter  11 B. Fourth power amplifier  9 CB is connected to fourth phase shifter  14 AA, and fourth output unit  15 BB is connected to fourth power amplifier  9 CB. 
     Fifth filter  17 C is for example a low-pass filter, and seventh filter  16 C is for example a high-pass filter. When fifth filter  17 C is a low-pass filter, and seventh filter  16 C is a high-pass filter, then the signal from signal source  8  is attenuated for low-pass frequency component by seventh filter  16 C, and high-pass frequency component is supplied to seventh power amplifier  9 CA. On the other hand, the signal from signal source  8  is attenuated for high-pass frequency component by fifth filter  17 C, and low-pass frequency component is supplied to third phase shifter  11 B. The cut-off frequency of seventh filter  16 C and the cut-off frequency of fifth filter  17 C are for example set to nearly same frequency. 
     Unit  18 C comprises signal source  8 , seventh filter  16 C, fifth filter  17 C, seventh power amplifier  9 CA, seventh output unit  15 BA, third phase shifter  11 B, fourth phase shifter  14 AA, fourth power amplifier  9 CB, and fourth output unit  15 BB. 
     And, eighth filter  16 D and sixth filter  17 D are connected to signal source  8 . Eighth power amplifier  9 DA is connected to eighth filter  16 D, and eighth output unit  15 AA is connected to eighth power amplifier  9 DA. Second phase shifter  14 BA is connected to sixth filter  17 D, third power amplifier  9 DB is connected to second phase shifter  14 BA, and third output unit  15 AB is connected to third power amplifier  9 DB. 
     Sixth filter  17 D is for example a low-pass filter, and eighth filter  16   d  is for example a high-pass filter. When sixth filter  17 D is a low-pass filter, and eighth filter  16 D is a high-pass filter, then the signal from signal source  8  is attenuated for low-pass frequency component by eighth filter  16 D, and high-pass frequency component is supplied to eighth power amplifier  9 DA. On the other hand, the signal from signal source  8  is attenuated for high-pass frequency component by sixth filter  17 D, and low-pass frequency component is supplied to second phase shifter  14 BA. The cut-off frequency of eighth filter  16 D and the cut-off frequency of sixth filter  17 D are for example set to nearly same frequency. 
     Unit  18 D comprises signal source  8 , eighth filter  16 D, sixth filter  17 D, eighth power amplifier  9 DA, eighth output unit  15 AA, second phase shifter  14 BA, third power amplifier  9 DB, and third output unit  15 AB. 
     Unit  12 AA is formed of unit  18 A and unit  18 B, and unit  12 BA is formed of unit  18 C and unit  18 D. 
     It is preferable to reverse the order in which third phase shifter  11 B and fourth phase shifter  14 AA are connected. 
     In the above configuration, first phase shifter  11 A, third phase shifter  11 B, fourth phase shifter  14 AA, and second phase shifter  14 BA are not disposed at third filter  16 A, fourth filter  16 B, seventh filter  16 C, and eighth filter  16 D. First phase shifter  11 A, third phase shifter  11 B, fourth phase shifter  14 AA, and second phase shifter  14 BA are disposed only at first filter  17 A, second filter  17 B, fifth filter  17 C, and sixth filter  17 D of which stationary waves give great influence to the ears. In this way, it is possible to efficiently reduce the worsening of sound quality due to low-frequency sound wave interference that occurs in all directions. In addition, when there exists a negative-phase frequency only at the low frequency side, it is possible to obtain higher sound quality because of including no modification of high-frequency sound. 
       FIG. 5  shows an example of another configuration in this preferred embodiment.  FIG. 5  is explained in the following mainly about the difference from  FIG. 4 . In the configuration of  FIG. 5 , fifth phase shifter  11 C and sixth phase shifter  11 D are added to the configuration of  FIG. 4 . As shown in  FIG. 5 , fifth phase shifter  11 C different in phase rotation center frequency from first phase shifter  11 A is disposed between first filter  17 A and first power amplifier  9 AB, and sixth phase shifter  11 D different in phase rotation center frequency from third phase shifter  11 B is disposed between sixth filter  17 D and third power amplifier  9 DB. In this way, the sound quality deterioration due to sound wave interference that occurs in the right and left direction of vehicle  13  can be reduced over a broad band between the group of fifth output unit  10 AA and first output unit  10 AB and the group of sixth output unit  10 BA and second output unit  10 BB. Similarly, the sound quality deterioration due to sound wave interference that occurs in the right and left direction of vehicle  13  can be reduced over a broad band between the group of eighth output unit  15 AA and third output unit  15 AB and the group of seventh output unit  15 BA and fourth output unit  15 BB. 
     It is preferable to reverse the order in which sixth phase shifter  11 D and second phase shifter  14 BA are connected. 
       FIG. 6  shows an example of further another configuration in this preferred embodiment.  FIG. 6  is explained in the following mainly about the difference from  FIG. 5 . In the configuration of  FIG. 6 , ninth phase shifter  19 A is disposed between third filter  16 A and fifth power amplifier  9 AA. And, tenth phase shifter  19 B different in phase rotation center frequency from ninth phase shifter  19 A is disposed between fourth filter  16 B and sixth power amplifier  9 BA. In this way, modification can be realized with high frequency component separated from low frequency component. 
     Similarly, eleventh phase shifter  19 C is disposed between seventh filter  16 C and seventh power amplifier  9 CA. And, twelfth phase shifter  19 D different in phase rotation center frequency from eleventh phase shifter  19 C is disposed between eighth filter  16 D and eighth power amplifier  9 DA. In this way, modification can be realized with high frequency component separated from low frequency component. 
       FIG. 7  is an example of further another configuration in this preferred embodiment.  FIG. 7  is explained in the following mainly about the difference from  FIG. 6 . As shown in  FIG. 7 , in place of ninth phase shifter  19 A, tenth phase shifter  19 B, eleventh phase shifter  19 C, and twelfth phase shifter  19 D in  FIG. 6 , delay filter  20 A is disposed between high-pass filter  16 A and fifth power amplifier  9 AA, and delay filter  20 B is disposed between fourth filter  16 B and sixth power amplifier  9 BA, and delay filter  20 C is disposed between seventh filter  16 C and seventh power amplifier  9 CA, and delay filter  20 D is disposed between eighth filter  16 D and eighth power amplifier  9 DA. In this way, it is possible to cope with the high frequency side where the cycle is short and the phase is greatly modulated. 
       FIG. 8  shows an example of further another configuration in this preferred embodiment.  FIG. 8  is explained in the following mainly about the difference from  FIG. 4 . In the configuration of  FIG. 8 , ninth phase shifter  19 A different in phase rotation center frequency from second phase shifter  14 BA is disposed between first filter  17 A and first power amplifier  9 AB. And, tenth phase shifter  19 B different in phase rotation center frequency from fourth phase shifter  14 AA is disposed between second filter  17 B and second power amplifier  9 BB. In this way, the sound deterioration due to sound wave interference that occurs in the front and rear direction of vehicle  13  can be reduced over a broad band. 
     It is preferable to reverse the order in which first phase shifter  11 A and tenth phase shifter  19 B are connected. 
     The preferred embodiment 1 of the present invention has been described with reference to the drawings. In this preferred embodiment, there is provided a controller (not shown) for controlling the characteristics of each phase shifter, each filter, and each delay filter, and it is possible to control each phase shifter, each filter and each delay filter to the desired characteristics by means of the controller. As a result of this control, the sound quality can be further optimized or the sound quality can be freely adjusted according to the user&#39;s liking. It is possible to install the controller in such position that it can be operated by the driver of vehicle  13 , and can also be installed in such position that it can be operated by any person at each seat of the vehicle. 
     INDUSTRIAL APPLICABILITY 
     The sound reproducing apparatus of the present invention is able to reduce the sound quality deterioration due to sound wave interference that occurs in the front and rear direction, which is therefore effective to improve the sound quality and useful in various sound reproducing apparatuses installed in vehicles such as automobiles.