Abstract:
An audio listening device includes a circuit for amplifying sound source signals and a mechanism including a bone conduction vibrator transforming an output signal of the amplifying circuit into a vibration. A vibration source transforms the output of the amplifying circuit into a first magnetic field and vibration. A vibration generating unit generates a second magnetic field for the vibration source to vibrate upwards and downwards due to attraction and repulsion processes of the first and second magnetic fields. A damper is connected to the vibration source to arouse air conduction hearing due to the vibration of the vibration source. A vibration plate is connected to the vibration source to arouse a bone conduction hearing due to the vibration of the vibration source. A vibration transmission unit transmits the bone conduction hearing and air conduction hearing to the hearing impaired.

Description:
This application is a Continuation-In-Part of application Ser. No. 08/609,866, filed Mar. 1, 1996. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an audio listening device which enables the hearing impaired to appreciate music signals by transforming soundwaves into vibration, and more particularly to an audio listening device for the hearing impaired having a serious obstacle to the path of the air conduction lying between the outer ear and the middle ear, with which the hearing impaired can receive stereo sonic high frequency signals above 200 Hz through bone conduction headphones using bone conduction hearing, and stereo sonic low frequency signals below 200 Hz through an existing spine vibration sheet using bone conduction hearing. 
     2. Description of Prior Art 
     An existing spine vibration device, composed of a vibration sheet, is devised for the non-impaired to receive low frequency signals by using the vibration of their spines transmitted from the spine vibration device, while they appreciate music signals by using air conduction hearing with the help of loudspeakers or headphones in their houses or cars. 
     However, the hearing impaired, having a serious obstacle to the path of the air conduction lying between the outer ear and the middle ear, have only been able to appreciate a low frequency component of music signals by using the vibration of their spines because the soundwaves from loudspeakers or headphones rarely reach their sensorineural system. 
     Furthermore, although the existing bone conduction vibrator can be substituted for loudspeakers or headphones, the hearing impaired can not hear the music signal due to the fact that the existing bone conduction vibrator is mainly designed for receiving voice signals whose frequency bandwidth is highly limited, and other problems come from the fact that neither the hearing impaired nor non-impaired can use the existing device together as it is designed for only bone conduction hearing. 
     SUMMARY OF THE INVENTION 
     Therefore, to solve the above mentioned problems, the purpose of the present invention is to provide an audio listening device for the hearing impaired which consists of bone conduction headphones fitted with a bone conduction vibrator using the principle of an ordinary loudspeaker, the loudspeaker unit and vibration plate to hear acoustic signals with broader frequency bandwidth by way of bone conduction and air conduction hearing, and consisting of the existing spine vibration system fitted with a vibration sheet. Accordingly, both the impaired and non-impaired can hear high frequency components of music signals through bone conduction headphones, resulting in the intelligibility reinforcement of music signals, and low frequency components of music signals through the existing vibration sheet to increase the naturality of music signals, respectively. 
     To accomplish the above mentioned purpose, the present invention is comprised of the following: a first means for amplifying external stereo sound signals to the predetermined level; a second means having a bone conduction vibrator which transforms directly the output signal of the first means into vibration so as to hear sound siganls by air conduction as well as bone conduction hearing; a third means for amplifying external stereo sound signals through a mixer/signal processor and a low pass filter; and a fourth means for transforming the output signal of the third means into vibration so as to arouse bone conduction hearing on the spine. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the accompanying drawings: 
     FIG. 1 is a block diagram illustrating the overall configuration of the present invention; and 
     FIG. 2 is a cross-sectional view of the bone conduction vibrator. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention will be described with reference to the embodiment illustrated in the accompanying drawings. 
     Referring to the accompanying drawings, FIG. 1 illustrates an audio listening device for hearing impaired which includes an audio amplifier 1, bone conduction headphones 2, a spine vibration adjusting amplifier 3 including a mixer/signal processor 3a, a low pass filter 3b and a power amplifier 3c, and a vibration sheet 4 including a sound/vibration transformer 4a and a vibration plate 4b. 
     FIG. 2 illustrates the bone conduction vibrator which includes a lower core 5, an electromagnet 6, the upper plate 7, a frame 8, a bobbin 9, a bobbin coil 9a, a damper 10, a vibration plate 11, a vibration contact part 12 and a coverlet 13. The present invention comprises the bone conduction headphones listening system adopting the principle of an ordinary loudspeaker in order to hear sound signals by air conduction hearing as well as bone conduction hearing, and a spine vibration system composed of the spine vibration adjusting amplifier 3 and the vibration sheet 4. 
     As illustrated in FIG. 1, the output signal of the audio amplifier, which amplifies applied external sound signals, is transmitted to the bone conduction headphones so that the hearing impaired and non-impaired cain hear the sound signal. The bone conduction headphones adopts the bone conduction vibrator as a drive in order to directly transform the applied sound signal into vibration, and also adopts the principle of an ordinary loudspeaker. 
     Consequently, the hearing impaired and non-impaired can hear the sound signals by both bone conduction and air conduction hearing. 
     On the other hand, the spine vibration system has two main parts. The first part is the spine vibration adjusting amplifier 3 comprising the mixer/signal processor 3a, for processing external signals, the low pass filter 3b, for passing only low frequency components among the output signals from the mixer/processor 3a, and the power amplifier 3c, for amplifying low frequency signals passing through the low pass filter 3b. The second part is the vibration sheet 4 comprising the sound/vibration transformer 4a and the vibration plate 4b, for transforming the output signal of the spine vibration adjusting amplifier 3 into vibration in order to arouse the bone conduction hearing sense on the spine. 
     Consequently, the hearing impaired can appreciate the low frequency component of music signals of which characteristic is dynamic and natural. 
     Referring to FIG. 2, the configuration of the bone conduction vibrator will be described below: 
     The bobbin coil 9a, which cain transform sound signals into a magnetic field, is wound around the cylindrical bobbin 9 perforated through the upper and lower parts so that the process of attraction or repulsion against the magnetic field of the fixed magnet can take place. 
     The impedance of the bobbin coil is matched with that of the already fixed vibrator. 
     The lower core 5, the electromagnet 6 and the upper plate 7 sequentially combined with the inside and outside of the bobbin 9 make the magnetic circuit for the bobbin 9 to move up and down together with the bobbin coil 9a. 
     The fixed magnet composed of the lower core 5, the electromagnet 6 and the upper plate 7 adopts the principle of an ordinary loudspeaker in order to reinforce the air conduction hearing, and also uses a small sized loudspeaker unit so as to appreciate the music signals having a broader frequency bandwidth than the voice signals. 
     Also, the fixed magnet is designed to have little flux leakage to maintain smooth vibration of the bobbin coil 9a at the gap between the lower core 5 and the electromagnet 6, and to narrow the gap for high efficiency of the magnetic circuit. 
     The frame 8, having a step-shaped part at its inside, is laid on the upper plate 7. The damper 10 and the vibration plate 11 are installed around the surface of the bobbin 9 with some interval between each other. The damper 10, supported on the frame 8, is used for reinforcing the air vibration for air conduction hearing resulting from the bobbin 9. The cross-shaped vibration plate 11, supported on the frame 8, keeps the air vibration of the damper 10 stable, and also arouses bone conduction hearing by vibrating up and down owing to the vibration of the bobbin 9 and the bobbin coil 9a. 
     As mentioned above, the overall vibration system consists of the bobbin 9, the bobbin coil 9a, the damper 10, and the vibration plate 11. The overall vibration system is supported by the frame 8 and covered with the coverlet 13 in order to keep the overall vibration, including the vibration of the vibration plate 11, stable. 
     On the other hand, the vibration contact part 12, forming a gap on its central axis, considering the efficiency of air conduction hearing from the vibration of the damper 10 as well as bone conduction hearing, is laid on the outer surface of the bobbin 9, and can be positioned after deciding the height and the curvature taking into account the contact surface with the face. 
     The bobbin 9 is supported and installed through the damper 10 and the vibration plate 11 in a space formed by the coverlet 13 and the frame 8, such that the bobbin 9 is spaced out at a predetermined distance from the bottom of the vibration contact part 12 and can be vibrated up and down. Therefore there is formed a path through which air medium can pass to the central gap of the vibration contract part 12 between the upper end of the bobbin 9 and the bottom of the vibration contact part 12. Sound waves (that is, air vibration generated by the vibration of the damper 10) can then be conveyed through the path toward the central gap of the vibration contact part 12, thus arousing air conduction hearing. As the bobbin 9 is supported at the frame 8 through the damper 10 and the vibration plate 11, the vibration of the damper 10 may also contribute to some extent to a bone conduction hearing together with the vibration plate 11. 
     The working flow of the bone conduction vibrator will be described as follows: 
     When external sound signals are applied to the bobbin coil 9a, a magnetic field is generated by the current flowing in the bobbin coil 9a. Due to both this magnetic field and another magnetic field generated from the fixed magnet comprising the lower core 5, the electromagnet 6 and the upper plate 7, attraction and repulsion process of two magnetic fields take place. Accordingly, the bobbin 9, wound by the bobbin coil 9a, moves up and down within the gap of the magnetic circuit. Subsequently, the cross-shaped vibration plate 11 vibrates and transmits its vibration to the vibration contact part 12 in order to arouse bone conduction hearing. 
     On the other hand, the vibration of the bobbin 9 causes the damper 10 to reinforce its air vibration which is able to arouse air conduction hearing by way of the vibration contact part 12. At this time, the frame 8 and the coverlet 13 keep the overall vibration of the damper 10 and the vibration plate 11, which results from the vibration of the bobbin 9, stable. 
     Therefore, the high frequency component of the music signals transmitted from the audio amplifier 1 can be heard by using the bone conduction headphones 2 having the bone conduction vibrator. 
     In other words, the overall working flow of the present invention is as follows: 
     At first, external stereo sound signals amplified by the audio amplifier 1 are transmitted to the bone conduction headphones 2 fitted with left and right bone conduction vibrators. When, the bone conduction vibrator follows the above mentioned working flow and, consequently, can arouse air conduction as well as bone conduction hearing. 
     Accordingly, in case the hearing impaired wear the bone conduction headphone 2 so that the vibration contact part 12 of the bone conduction vibrator is positioned exactly at the optimum contact point on the face they are able to hear stereo sounds signals by bone conduction hearing. Furthermore, in case the non-impaired wear the headphones on their ears just like ordinary-headphones, they can also hear stereo sound signals through air conduction hearing. 
     Also, in case external stereo signals are applied to the spine vibration adjusting amplifier 3 consisting of the mixer/signal processor, the output signal has a low frequency component. Then, the output signals are transmitted to the sound/vibration transformer 4a in which the sound signals are transformed into vibration for vibrating the vibration sheet 4b. 
     The effect of the present invention is described below: 
     The bone conduction headphones 2 gives the hearing impaired the clearness, in other words, high frequency characteristics of music signals by using the bone conduction hearing sense at the skull. On the other hand, the vibration sheet 4 gives dynamic and natural characteristics of a low frequency component to the hearing impaired by using bone conduction hearing sense at the spine. 
     Therefore, the hearing impaired can use the present invention as a music appreciation system because the bone conduction headphones 2 are fit for the broadband frequency signal such as TV or radio signals. 
     Moreover, the non-impaired can also use the present invention because the bone conduction headphones 2 adopt the priniciple of an ordinary loudspeaker.