Patent Publication Number: US-8978314-B2

Title: Mobile terminal booth

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to Japanese Patent Application No. P2012-169101, filed Jul. 31, 2012; and U.S. patent application Ser. No. 13/954,636, filed Jul. 30, 2013. 
     FIELD OF INVENTION 
     The present invention relates to a mobile terminal booth for providing an area where a mobile terminal can be comfortably used in a public area or the like. 
     DESCRIPTION OF RELATED ART 
     Currently, the penetration rate of cellular phones and smartphones has exceeded 100 percent of the Japanese population, and almost all the Japanese have communication devices at all times. Such mobile terminals are convenient to make it possible to collect and transmit information or have telephone conversations, for example, by using spare time effectively on the move. In fact, a significant proportion of people in a park, a building, a street or the like public area are using mobile terminals for some purposes. 
     However, when a person has a telephone conversation on the move with a mobile terminal, it is common that the person talks beside other passengers, unlike having a telephone conversation with a public phone in a telephone booth. Accordingly, it is often difficult to hear the other person&#39;s voice in loud places, e.g., in a crowded street. 
     Even in a station yard or in a building, noise tends to be reverberating in the enclosed space so that it is sometimes difficult to talk in a relaxed way. Usually, when having a telephone conversation, a person moves close to a wall or the like where noise seems to be smaller. The noise level near a wall, however, is never small because of reverberating sound reflected from the wall. The reverberating sound often makes it difficult also for the person at the other end to hear the voice. On the other hand, however, it is not a good idea to have a conversation in the middle of a walkway. 
     Also, since the conversation may be heard by others nearby, there is some reluctance to talk a personal fact. Furthermore, it is not well-mannered and often an annoyance to other passengers to use a mobile terminal or nave telephone conversation while walking. 
     There are commercially available booths for cellular phones similar to conventional public phone rooms. These booths or conventional public phone rooms are cuboid boxes forming an enclosed space with a door provided in one side for entry. The sides of such a box are formed of transparent walls such as glass plates from the viewpoint of security and giving the space an open feeling. The inside space is completely confined and separated from outside because it is believed that a noiseless space is created by eliminating any sound passage between the inner space and the outside. 
     However, this consideration is not true at least in the case where a comfortable space is wanted for the purpose of using a mobile terminal. The confined structure forms a reverberation space in which noise is reverberating. The sound entering through the glass plates is not so large, but tends to make an inside person feel loud the reverberation. Particularly, the voice and other sound output from this inside person also become such reverberating noise. Also, a substantial space has to be prepared in order to install such a box provided with a door space has to be spared In addition, the production cost is relatively high. Furthermore, it seems somewhat heavy to install and use the box for the purpose of using a mobile terminal. 
     It is therefore an object of the present invention to provide a mobile terminal booth which can be used for having telephone conversation with comfort, less stress and no hesitation. 
     SUMMARY OF THE INVENTION 
     To achieve at least one of the above mentioned objects, mobile terminal booth comprises: a sound absorbing unit which is placed in a public place and partially partitions a space as viewed from the above where a user of a mobile terminal can have a telephone conversation, wherein said sound absorbing unit is provided with an entrance which is always opened without any closing member, wherein said sound absorbing unit is provided with a sound controlling member. 
     In accordance with a preferred embodiment, said sound absorbing unit includes a sound absorbing layer. 
     Also, in a preferred embodiment, said sound absorbing layers are made from at least one of a needle felt, bestray, softray, glass wool, thermo wool, phenol resin, and polyurethane. 
     In accordance with a preferred embodiment, said sound absorbing unit is made of a laminate consisting of a plurality of sound absorbing layers, and said sound absorbing layers are joined together in the form of said laminate with an adhesive. 
     Furthermore, in a preferred embodiment, said adhesive is a viscous adhesive which does not solidify after formation of said laminate, maintains its viscosity when the mobile terminal booth is used and functions as said sound controlling member. 
     Furthermore, in a preferred embodiment, said laminate is formed with a resin sheet interposed between each adjacent ones of said sound absorbing layers. 
     Furthermore, in a preferred embodiment, said resin sheet is a vinyl film having a thickness of 0.1 mm to 0.5 mm. 
     Furthermore, in a preferred embodiment, said resin sheet is provided with a plurality of openings, wherein said sound absorbing layers are directly adhered with each other by said adhesive through said openings, and indirectly adhered with each other by said adhesive through said resin sheet. 
     Furthermore, in a preferred embodiment, the mobile so terminal booth further comprises a plurality of support posts which support said sound absorbing unit at a predetermined height. 
     Furthermore, in a preferred embodiment, said sound absorbing unit consists of a plurality of sound absorbing panels which are joined to confine said partitioned space. 
     Furthermore, in a preferred embodiment, said sound absorbing panel includes a sound absorbing member and a support panel on which said sound absorbing member is mounted, and the outer side of said support panel is at least partially opened. 
     Furthermore, in a preferred embodiment, the outer side of said support panel serves as a sound blocking surface. 
     Furthermore, in a preferred embodiment, said support panel is made of aluminum. 
     Furthermore, in a preferred embodiment, the mobile terminal booth further comprises a roof member which covers the top of said mobile terminal booth and encloses the inside space of said mobile terminal booth from the above. 
     Furthermore, in a preferred embodiment, said sound absorbing unit is in the form of an arc in a plan view. 
     Furthermore, in a preferred embodiment, said sound absorbing unit is in the form of a polygon in a plan view. 
     Furthermore, in a preferred embodiment, said polygon is a rectangle, a square or a pentagon, whose one side is at least partially opened. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The objects and features of the present invention will become more apparent from consideration of the following detailed description taken in conjunction with the accompanying drawings in which: 
         FIG. 1  is a perspective view for showing a mobile terminal booth in accordance with an embodiment 1 of the present invention. 
         FIG. 2  is an exploded perspective view for showing the structure of the plate-like sound absorbing panel in accordance with the embodiment 1 of the present invention. 
         FIG. 3  is a cross sectional view for showing the sound absorbing structure of a sound absorbing member used in the mobile terminal booth of the embodiment 1. 
         FIG. 4  is a plan view for showing a vinyl film which is inserted between the sound absorbing member shown in  FIG. 3  and through which a number of openings are formed. 
         FIG. 5  is a cross sectional view for showing the sound absorbing structure as described in International Patent Published Application (WO2006/134654). 
         FIG. 6  is a cross sectional view for showing the structure of the plate-like sound absorbing panel used in the mobile terminal booth of the embodiment 1. 
         FIG. 7  is a partial cross-sectional view for showing the structure of the plate-like sound absorbing panel used in the mobile terminal booth of the embodiment 1. 
         FIG. 8  is a plan view for showing a roof member which is used for the mobile terminal booth of an embodiment 2. 
         FIG. 9  is a plan view for snowing the mobile terminal booth of the embodiment 2. 
         FIG. 10  is a plan view for showing another roof member which is used for the mobile terminal booth of the embodiment 1. 
         FIG. 11  is a perspective view for showing the mobile terminal booth in accordance with an embodiment 3. 
         FIG. 12  is a plan view for showing the mobile terminal booth in accordance with the embodiment 3 on which a roof member is mounted. 
         FIG. 13  is a cross sectional view for showing a modification example of the sound absorbing unit of the mobile terminal booth explained as art embodiment 4. 
         FIG. 14  is a cross sectional view for showing another modification example of the sound absorbing unit of the mobile terminal booth explained as the embodiment 4. 
         FIG. 15  is a cross sectional view for showing a further modification example of the sound absorbing unit of the mobile terminal booth explained as the embodiment 4. 
         FIG. 16  is a plan view for showing a further modification example of the mobile terminal booth explained as the embodiment 4. 
         FIG. 17  is a cross sectional view, taken along line A-A of  FIG. 16 , for showing the sound absorbing unit. 
         FIG. 18  is a front view for showing a further modification example of the mobile terminal booth explained as the embodiment 4. 
         FIG. 19  is a perspective view for showing a further modification example of the mobile terminal booth explained as the embodiment 4. 
         FIG. 20  is a perspective view for showing a mobile terminal booth in accordance with an embodiment 5 of the present invention. 
         FIG. 21  is a perspective view for showing a replaceable billboard which can be attached to the mobile terminal booth of the embodiment 5. 
         FIG. 22  is a perspective expanded view for partially showing the replaceable billboard shown in  FIG. 21  as seen from the back side. 
         FIG. 23  is a perspective expanded partial view for showing the way of mounting the replaceable billboard shown in  FIG. 21  on the mobile terminal booth of the embodiment 5. 
         FIG. 24  is a perspective view for showing the mobile terminal booth of the embodiment 5 on which the replaceable billboard shown in  FIG. 21  is mounted. 
         FIG. 25  is a perspective view for showing a modification the mobile terminal booth in accordance with the embodiment 5. 
         FIG. 26  is a perspective view for showing a mobile terminal booth in accordance with an embodiment 6 of the present invention. 
         FIG. 27  is an exploded perspective view for showing the structure of the plate-like sound absorbing panel in accordance with the embodiment 6. 
         FIG. 28  is a cross sectional view for snowing the structure of the plate-like sound absorbing panel used in the mobile terminal booth of the embodiment 6. 
         FIG. 29  is a plan view for showing another example of the plate-like sound absorbing panel used in the mobile terminal booth of the embodiment 6. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In what follows, a mobile terminal booth in accordance with several embodiments of the present invention will be explained with reference to the accompanying drawings. This mobile terminal booth can be installed in a station yard, a lobby, a street or the like. When making a call, a user of a cellular phone can get away from reverberating sound by entering this mobile terminal booth. It is possible to prevent the conversation from being heard by others nearby. Furthermore, the user can enjoy the conversation without worrying about other people who might be looking at the user. 
     Embodiment 1 
       FIG. 1  is a perspective view for showing a mobile terminal booth in accordance with a first embodiment of the present invention. This mobile terminal booth  100  includes a sound absorbing unit  110  in the form of a cylinder having a front opening, and a support frame  120  for supporting the sound absorbing unit  110 . Each of the sound absorbing unit  110  and the support frame  120  can be carried as several constituent parts and assembled in an installation site. 
     The sound absorbing unit  110  can be assembled by connecting a number of plate-like sound absorbing panels  111  in the form of an arch. Each sound absorbing panel is, for example, 20 cm wide, 60 cm high and 3 cm thick. Also, the support frame  120  includes four pipes (support posts) to be vertically connected to the sound absorbing unit  110 , and adjuster foots  123  attached to the bottom surfaces of the pipes  121 . 
     If the length of the pipes  121  is 1.80 cm, the lower end of the sound absorbing unit  110  is located 120 cm from the floor. The sound absorbing unit  110  is effective when it is taller than the user of this mobile terminal booth  100 . Generally speaking, the upper end of the plate-like sound absorbing panel  111  is located 10 to 15 cm higher than the average height of the country where the mobile terminal booth  100  is installed. 
     As illustrated in  FIG. 2 , the plate-like sound absorbing panel  111  is assembled by mounting a sound absorbing member  115  on an aluminum panel (support panel)  113 . This sound absorbing member  115  is “Room Creator” which House  119  co. Ltd. has sold. After mounting the sound absorbing member  115  on the aluminum panel  113 , panel caps  117  are fitted onto the top and bottom ends of the aluminum panel  113 . Also, as illustrated in  FIG. 1 , a plurality of the plate-like sound absorbing panel  111  are connected to each other as the sound absorbing unit  110  in the form of a cylinder having an opening in the front side. In this case, the angle subtended by the opening and as seen from the center of the cylinder is 90 to 120 degrees, i.e., ¼ to ⅓ of the circumference. This angle range is important for this purpose and has been found by the inventor through experiments. 
     Generally speaking, the term “sound insulation” has two meanings. One of them is absorption capabilities of absorbing sound waves incident on the panel by converting the incident sound waves to thermal energy. The other is reflection capabilities of blocking sound waves incident on the panel by reflecting the incident sound waves and preventing them from entering inside. 
     Both are effective to prevent sound from leaking one side to the other side. What required of a sound insulating wall is to prevent sound from leaking one side to the other side. However, when enjoying music and so forth, sound reverberates with the sound insulating wall so that the space becomes not comfortable, and the bandwidth of reproduced sound is narrowed. 
     When a person is about to use a cellular phone, he often moves to a position near a wall or a corner which seems relatively noiseless. However, such a position is not a better position in terms of a sound environment because sound reverberation occurs particularly near walls. Accordingly, from the viewpoint of the purpose, the absorption capabilities are particularly important. 
       FIG. 3  is a cross sectional view for showing the sound absorbing structure of “Room Creator” (sound absorbing member  115 ). The Room Creator is an excellent sound controlling material used in the mobile terminal booth of the embodiment 1. The sound absorbing structure includes a pair of sound absorbing sheets  115   a  bonded as a laminate together with an intervening thin vinyl film  115   b  therebetween. The vinyl film  115   b  functions as a sound scattering. The sound absorbing sheet  115   a  is made of a needle felt which functions as a sound absorbing material. Other sound absorbing material which can be used for this purpose includes glass wool, thermo wool, bestray, softray, phenol resin, and polyurethane. The thickness of the sound absorbing sheet  115   a  is for example 1 to 2 cm, and the thickness of the vinyl film  115   b  is for example 0.1 mm through 0.5 mm. Furthermore, the back side of the sound absorbing member  115  is covered by a soft polyvinyl chloride plate  115   c  for the purpose of supporting and protecting the sound absorbing member  115 . Also, the other inner side is covered by a cloth  115   d . The total thickness of the sound absorbing member  115  is thereby about 2 to 4 cm. 
       FIG. 4  is a plan view for showing the vinyl film  115   b  which is inserted between the sound absorbing members  115  shown in  FIG. 3  and through which a number of openings  115   h  are formed. For example, the diameter of each opening  115   h  is 2 cm, and adjacent ones thereof are located 7 cm distant from each other. With the openings  115   h , the incident sound waves can be effectively scattered in the lateral direction to enhance the sound absorbing capabilities of the sound absorbing member  115 . In addition, the openings  115   h  allow part of the incident sound waves to pass through the vinyl film  115   b  to control the balance between reflection and transmission, such that they functions as a sound controlling means. 
     The vinyl film  115   b  and the sound absorbing sheets  115   a  are joined with a viscous adhesive. The viscous adhesive is applied also between the sound absorbing sheets  115   a  through the openings  115   h . While binding the vinyl film  115   b  and the sound absorbing sheets  115   a  together, this viscous adhesive maintains a certain viscosity. Also, while maintaining a certain viscosity, this viscous adhesive intervenes between the sound absorbing sheets  115   a  through the openings  115   h . In other words, it is important that, when the sound absorbing member  115  is used, the viscous adhesive shall not be solidified but can provide a glutinous layer between the vinyl film  115   b  and the sound absorbing sheets  115   a  and between the sound absorbing sheets  115   a.    
     This sound absorbing structure is described in International Patent Application No. PCT/JP2011/58944, and capable of absorbing incident sound waves in a wide range from very low frequencies to very high frequencies. Particularly, for this purpose, it is important that the sound absorbing structure can substantially dump sound pressure levels at 500 Hz or higher frequencies which phone users feels noisy. On the other hand, it is considered difficult to maintain sound absorbing capabilities at low frequencies. Even it only high frequency components are dumped, it is an unnatural sound environment so that when entering the booth, the user feels somewhat incommodity. Contrary to this, it sound components are uniformly dumped, the user feels a natural sound environment and, even though confined, receive the impression that the space is expanded. 
     The sound absorbing member  115  may be formed by the use of the sound absorbing structure as described in International Patent Published Application (WO2006/134654). This sound absorbing structure is characterized in that the incident sound waves are passed through a passage constructed by a wall whose cross section is gradually decreased from the sound entry side. That is, the opening area of the passage perpendicular to the direction of the incident sound waves is is gradually decreased from the sound entry side to form a narrowing passage. This structure is useful in that it can absorb wide band sound waves. 
       FIG. 5  is a cross sectional view for showing the sound absorbing structure as described in International Patent Published Application (WO2006/134654). As illustrated in  FIG. 5 , a number of cylindrical sound absorbing members  12  are arranged in parallel with each other perpendicular to the plane of the drawing sheet. A sound absorbing material  20  is provided with to fill the space between each adjacent ones of the cylindrical sound absorbing members  12 . In this case, each cylindrical sound absorbing member  12  is a cylinder made of an acrylate resin. The cylindrical sound absorbing members  12  are slightly distant from each other to form a narrowing passage  11  which is filled with the sound absorbing material  20 . The longitudinal direction of the sound absorbing members  12  is aligned with in the longitudinal direction of the plate-like sound absorbing panel  111 , which is then covered with a fabric to make up the sound absorbing member  115 . 
     The reverberating sound can be dumped in the mobile terminal booth by the use of the sound absorbing member  115  as described above to make it possible to have telephone conversation in a quiet environment. 
     As illustrated in the cross sectional view of  FIG. 6  and the expanded cross sectional view of  FIG. 7 , the plate-like sound absorbing panel  111  is provided with a cylindrical lobe  113   e  projected from one side of the aluminum panel  113 , and a lobe receptor  113   g  formed in the other side of the aluminum panel  113  and capable of pivotally engaging with the lobe receptor  113   g . Each adjacent ones of the plate-like sound absorbing panel  111  are linked by inserting and sliding the cylindrical lobe  113   e  into the corresponding lobe receptor  113   g  in the longitudinal direction. The pipes  121  are connected to the plate-like sound absorbing panel  111  by screw clamp on the side surface of the plate-like sound absorbing panel  111 . 
     The plate-like sound absorbing panels  111  are joined in the form of an arc as seen in plan view so that the incident sound waves from the rear and lateral sides can be dumped. On the other hand, the sound waves incident from the front side, i.e., through the opening of the arc cannot be directly dumped. However, this is an important point of the present invention. When a person feels suffocated in a narrow space, it results from reverberating sound in many cases. For example, many people do unexpectedly not feel noisy in an outdoor open place even when a multitude of people are gathered. 
     This sound absorbing structure is characterized in that incident sound waves are scattered in lateral directions to dump reverberating sound so that the space is felt as if it extending outwards through the panel and also through the wall behind the panel. Accordingly, in the case of this mobile terminal booth having the sound absorbing structure as described in PCT/JP2011/58944 (or WO2006/134654), a comfortable space can be provided without making shrill noise which would be reverberating inside it the booth were designed to form a completely closed structure. 
     The applicant has made two prototypes of this mobile terminal booth, and verified the sound absorbing capabilities thereof by experiments. The prototypes were placed in a room having an area of 132 square meters and a height of 2.7 meters. The tools for the experiments were Pro tools LE7 (hereinafter referred to as PT) as a recorder and a signal generator, AKG C451 as a microphone, Digidesign 002 as a microphone amplifier and SONY SMS-1P as a powered speaker. 
     First, the microphone was placed in the center position of the prototypes (i.e., the center of the cylinder formed of the plate-like sound absorbing panels), and the speaker was placed 3 meters distant from the opening of the panel. Pink noise generated by PT was reproduced from the speaker, and the reproduced sound was recorded through the microphone for 30 seconds. The recording format was 24 bits and 48 kHz. The sound data recorded by PT was stored as data of 16 bits and 44.1 kHz, and frequency analyzed (FFT) by “Wave Spectra” which is a Windows (registered trademark) software. 
     One of the prototypes has been made of twenty four plate-like sound absorbing panels having a width of 10 cm. The other prototype has been made of eight plate-like sound absorbing panels having a width of 30 cm. The height of each type of panel was 60 cm. The same experiments were conducted with a booth made from concrete panels as a comparative example in place of the plate-like sound absorbing panels of the mobile terminal booth. 
     As experimental results, there were little substantial differences between 10 cm and 30 cm widths of the plate-like sound absorbing panels. However, when the gaps between the plate-like sound absorbing panels increased, there were observed small differences at 1 kHz or higher frequencies which might be influenced by reflection at the gaps. 
     In the case of the comparative example using the concrete panels, the sound pressure levels were higher than those of the prototypes using the plate-like sound absorbing panels throughout all the frequency range as measured. Particularly, the differential sound pressure levels between the comparative example and the prototypes were up to a maximum of 20 dB in the audible frequency range. These differences were clearly felt by ears. As a result, it was found that the plate-like sound absorbing panel is significantly effective for inhibiting reverberating sound. 
     Furthermore, comparative experiments were conducted with the plate-like sound absorbing panels having a width of 30 cm and simply arranged in a flat plane to form an absorbing wall, and the same plate-like sound absorbing panels arranged in a cylinder having an opening to form a 270° arc as described above. As a result, there were significant differences around 300 Hz and 550 Hz, and 2 kHz through 4 kHz. The frequency components around 300 Hz and 550 Hz correspond to muffled sounds so that, in the case of telephone conversations with cellular phones, it is greatly influenced by these frequency components whether or not voices can be heard clearly. Accordingly, by arranging the panels in a circle, it is understood that voices can be heard easily. This is true also for the person at the other end. 
     Furthermore, in either experiment, the sound pressure levels at 10 kHz or higher frequencies were higher than those at lower frequencies by about 20 dB. This seems because of sound reflection on the surface of the plate-like sound absorbing panel or sound reflection at the gap between adjacent panels. Incidentally, while the height of each type of panel was 60 cm, the reduction of the sound pressure levels can be further increased by making use of higher panels as well as reflection from the opening. 
     Meanwhile, the aforementioned structure is effective to dump sound waves other than those reflected inside the mobile terminal booth. For example, the rear (outside) surface of the sound absorbing unit is made of the aluminum panel  113  which reflects and blocks sound waves incident from outside. The aluminum panel  113  therefore improves the sound reduction effect of the mobile terminal booth against the sound waves entering through the mobile terminal booth. A convenient sound field can thereby be provided in which cellular phone users can have telephone conversations with comfort and less stress. Needless to say, the aluminum panel can be replaced with another sound blocking panel such as that made of a metal or alloy, e.g., steel, duralumin, titanium, or a non-metallic material, e.g., reinforced plastic material, wood or the like. 
     Embodiment 2 
     This embodiment includes a roof member on the top of the mobile terminal booth of the embodiment 1. As illustrated in  FIG. 8 , this roof member  201  is formed in the shape of a semicircle disk having a semicircular cut-out portion  203 . The roof member  201  has a total area covering 30% to 40% of the upper opening of the cylindrical mobile terminal booth.  FIG. 9  is a plan view as seen from the above for showing the mobile terminal booth  100  of the embodiment 1 on which the roof member  201  is attached. 
     The roof member  201  is simply mounted on the mobile terminal booth so that its strength need not be so high. Accordingly, the roof member  201  consists of a sound absorbing member  207  mounted on a base plate  205  made of aluminum or a plastic material such as ABS resin. The sound absorbing member  207  is made of “Room Creator” as described above. The base plate  205  is provided with three through-holes  209  along its periphery, and can be fixed to the mobile terminal booth with screws which are inserted through the through-hole  209  into internal threads (not shown in the figure) which are formed through the panel caps  117 . 
     With the roof member  201 , it is possible to block sound waves entering from the above and make the inside space more silent. Since the roof member  201  covers only part of the upper opening of the mobile terminal booth rather than all the area of the upper opening, it is possible to have outside light enter the mobile terminal booth and give the inside space an open feeling. However, the roof member  201  may be designed in the form of a disk to cover all the area of the upper opening as illustrated in  FIG. 10  and improve the sound blocking performance. 
     Embodiment 3 
       FIG. 11  is a perspective view for showing a mobile terminal booth  300  in accordance with an embodiment 3. The difference between this mobile terminal booth  300  and the mobile terminal booth  100  of the embodiment 1 is that the support frame  120  is replaced with a support frame  320  which is fixed to the bottom of a sound absorbing unit  310 . In what follows, the differences from the embodiment 1 will be described. 
     The sound absorbing unit  310  can be assembled by connecting a number of plate-like sound absorbing panels  311  in the form of an arch. Each sound absorbing panel is, for example, 20 cm wide, 60 cm high and 3 cm thick. Also, the support frame  320  includes four pipes to be vertically connected to the sound absorbing unit  310 , two arch members  323  each of which links the centers of two of the pipes  321  together, and disk plates  325  attached to the bottom surfaces of the pipes  321 . The disk plates  325  are provided with rubber sheets attached to the bottom surface of the disk plates  325 . The length of the pipes  321  is 120 cm. 
     The tops of the pipes  321  are externally threaded in the form of screws. On the other hard, the panel caps  317  are provided with internally threaded holes (not shown in the figure). The pipes  321  can be fastened to the panel caps  317  by rotating and inserting the screws of the pipes  321  into the threaded holes of the panel caps  317 . The pipes  321  are formed with through-holes  329  through which the arch members  323  can be inserted. The arch members  323  can be fixed to the pipes  321  with hex nuts  327  having threaded holes to be engaged with the ends of the arch members  323  which are externally threaded and passed through the through-holes  329 . 
     Furthermore, the lower ends of the pipes  321  are internally threaded (not shown in the figure). On the other hand, externally threaded portions are projected upward from the top surface of the disk plates  325  and can be engaged into the lower ends of the pipes  321  by relative rotation. This structure makes the mobile terminal booth appearing simple and elegant with the sound absorbing unit  310  and having a sufficient strength with the arch members  323 . Meanwhile, it is also effective that the roof member  201  as described above is mounted on the mobile terminal booth of this embodiment as illustrated in  FIG. 12 . 
     Embodiment 4 
     in what follows, several modifications of the above embodiments will be explained. In the case of the embodiment 1, the sound absorbing unit  110  has a cross section in the form of a circle having an opening. However, the sound absorbing unit can be shared to have a cross section in the form of a polygon (such as a rectangle, a square, a pentagon) from which one side is removed. One side of this polygon is least partially opened. 
     For example, as illustrated in  FIG. 13 , the space utilization of the sound absorbing unit  340  can be maximized by making use of a squared form to provide more choices of where the mobile terminal booth is placed. Then, the user-friendliness can be improved when assembling, installing and utilizing the mobile terminal booth. Alternatively, as illustrated in  FIG. 14 , the front opening can be narrowed in order to improve the sound controlling performance. 
     On the other hand, the sound absorbing unit can be shaped in the form of a two-panel screen  350  (or having an L-shaped cross section) as illustrated in  FIG. 14 . This configuration provides a sense of openness where a user can make use of the mobile terminal booth with ease as if the user simply steps to a wall. In addition, the cost can be minimized. 
     The sound absorbing units as illustrated above can be constructed by basically combining the same plate-like sound absorbing panels. However, the structures as illustrated in  FIGS. 13 through 15  can be constructed also by the use of a single larger plate-like sound absorbing panel for each side of the squared form in place of a number of small panels as described above. In this case, the number of steps for assembling a sound absorbing unit can be significantly reduced, and the silent performance can be improved due to a few number of joint portions.  FIG. 16  is a perspective view for showing a mobile terminal booth with a sound absorbing unit consisting of left, right and back panels  361 L,  361 R and  361 B each of which is made of a single larger plate-like sound absorbing panel. Also,  FIG. 17  is a cross sectional view, taken along line A-A of  FIG. 16 , for showing the sound absorbing unit of this mobile terminal booth. A pair of support posts  362 L are attached to the opposite edges of the left side  361 L, and a pair of support posts  362 R are attached to the opposite edges of the right side  361 R. This mobile terminal booth is provided further with a roof member  361 T. 
     Furthermore, the sound absorbing unit  110  of the embodiment 1 can be extended downward to the floor as a sound absorbing unit  330  as illustrated in  FIG. 18 . In this case, the sound absorbing performance can be furthermore improved such that more quiet space can be created. Particularly, a woman is no longer worried about other people&#39;s eyes since her legs are hidden by the sound absorbing unit  330 . The roof member  201  of the embodiment 2 can be mounted also on the mobile terminal booth shown in  FIG. 18  to create a more quiet space. 
     Furthermore, in the case where a number of plate-like sound absorbing panels are assembled to form a sound absorbing unit as described above, it is inevitable that the reverberating performance and the sound absorbing performance are reduced to some extent at the connecting portions. However, as illustrated in  FIG. 19 , the influence of the connecting portions can be avoided by making use of a single cylindrical plate-like sound absorbing panel  211  from which an entrance portion is cut out. In this case, the plate-like sound absorbing panel  211  can continuously cover the inner space without connecting portions. 
     Embodiment 5 
       FIG. 20  is a perspective view for showing a mobile terminal booth in accordance with a fifth embodiment of the present invention. This mobile terminal booth  400  includes a sound absorbing unit  410  in the form of a cylinder having a front opening, and a support frame  420  for supporting the sound absorbing unit  410 , in the same manner as the mobile terminal booth of the embodiment 1. Each of the sound absorbing unit  410  and the support frame  420  can be carried as several constituent parts and assembled in an installation site. 
     The sound absorbing unit  410  can be assembled by connecting a number of plate-like sound absorbing panels  411  in the form of an arch. Each sound absorbing panel is, for example, 20 cm wide, 60 cm high and 3 cm thick. Also, the support frame  420  includes four pipes  421   b  and  421   f  to be vertically connected to the sound absorbing unit  410 , and adjuster foots  423  attached to the bottom surfaces of the pipes  421   b  and  421   f.    
     If the length of the pipes  421   b  and  421   f  is 200 cm, the lower end of the sound absorbing unit  410  is located 80 cm from the floor. The sound absorbing unit  410  has the same structure as that of the embodiment 1 except for its size. Additionally, a roof member as shown in  FIG. 10  is provided on the top of the sound absorbing unit  410 . 
     Furthermore, the mobile terminal booth of this embodiment is provided with an arch-like connector  440  which bridges between the upper portions of the plate-like sound absorbing panels located at opposite sides of the front opening (entrance) of the sound absorbing unit  410 . This arch-like connector  440  serves to reinforce the stability of the mobile terminal booth. Accordingly, while the plate-like sound absorbing panels  411  are pivotally joined with each other, the diameter of the mobile terminal booth can be changed by making use of an arch-like connector having a different span as the arch-like connector  440 . 
     Furthermore, the inner and outer surfaces of the sound absorbing unit may be used as an advertising space so that certain earnings can be expected. The mobile terminal booth of the embodiment 5 is further provided with a replaceable billboard.  FIG. 21  is a perspective view for showing this replaceable billboard. As shown in this figure, the replaceable billboard  430  consists of an advertisement plate  432  made of a plastic and a pair of supporting poles  434  to which the opposite ends of the advertisement plate  432  are fixed. 
     As illustrated in  FIG. 22 , the advertisement plate  432  is fixed to the supporting poles  434  with screws  434   s , and can be replaced with another advertisement plate. Also, as illustrated in  FIG. 23 , the two front side pipes  421   f  are provided with support holes  421   h  at their upper ends. On the other hand, the supporting poles  434  are provided with support rods  434   r  which are projected downward and inserted into the support holes  421   h  of the front side pipes  421   f  so that the replaceable billboard  430  can be mounted on the top of the sound absorbing unit  410  as illustrated in  FIG. 24 . 
       FIG. 25  is a perspective view for snowing a modification the mobile terminal booth in accordance with the fifth embodiment. This mobile terminal booth  450  is provided with an arch-like connector  452  in place of the arc-like connector  440  as shown in  FIG. 20 . The arch-like connector  452  is provided to project upward from the top of the sound absorbing unit  410  in the position corresponding to the replaceable billboard  430  as illustrated in  FIG. 24 . More specifically, the mobile terminal booth  450  has front two pipes  451   f  which are extending upwards beyond a roof member  455  in the same manner as the supporting poles  434  of the mobile terminal booth  400  shown in  FIG. 24 . The arch-like connector  452  is fixed between the extended portions of the pipes  451   f . This arch-like connector  452  serves to reinforce the stability of the mobile terminal booth without narrowing the front opening (entrance) of the sound adsorbing unit  450 . 
     Embodiment 6 
       FIG. 26  is a perspective view for showing a mobile terminal booth in accordance with a sixth embodiment of the present invention. This mobile terminal booth  500  differs from the mobile terminal booth of the embodiment 1 in the structure of the sound absorbing unit. Specifically speaking, plate-like sound absorbing panels  511  have a different structure. 
       FIG. 27  is an exploded perspective view for showing the plate-like sound absorbing panel  511  of this mobile terminal booth  500 .  FIG. 28  is a cross sectional view for showing the plate-like sound absorbing panel  511 . The plate-like sound absorbing panel  511  is assembled by mounting a sound absorbing member  515  on an aluminum panel  513  in the same manner as that of the embodiment 1. 
     However, the outer side of the aluminum panel  513  is at least partially opened. In this case, a plurality of vertical slits  514  are formed through the aluminum panel  513 . Namely, the front side of the aluminum panel  513  is in the form of a grille through which the inside sound absorbing member  515  is exposed. Except for the formation of the grille, the plate-like sound absorbing panel  511  is the same as the plate-like sound absorbing panel  111  of the embodiment 1. As compared with the structure shown in  FIG. 2 , this structure shown in  FIG. 27  is less effective to reflect and block sound waves incident from outside, but more effective to inhibit reverberating sound inside the mobile terminal booth. Namely, in the case of the first embodiment, the inner surface of the aluminum panel  113  reflects sound waves that are propagating from the inside space of the mobile terminal booth, passed through the sound absorbing member  115  and incident on the inner side the sound absorbing panel  111 , and thereby enhances reverberating sound in the inside space. However, in the case of this embodiment, such sound waves incident on the inner side the sound absorbing panel  111  are transmitted through the vertical slits  514  of the aluminum panel  513  outwards from the inside space of the mobile terminal tooth, so that reverberating sound can be inhibited. 
     Accordingly, the grille  513   g  serves to reduce reverberating sound waves which contains much high-frequency components, and thereby can function as a means of controlling sound inside the mobile terminal booth. Generally speaking, it is effective for the same purpose to (partially) remove the center portion of the aluminum panel  513 . For example,  FIG. 29  shows another example of such an aluminum panel from which the center portion thereof is removed. The aluminum panel consists of an outer rim  516  and a plurality of strips  517  inside the rim in the form of a criss-crossed pattern. The sound absorbing member  515  is exposed through the criss-crossed pattern. 
     The mobile terminal booth of the present invention may be used to serve also as a guide booth which is installed, for example, in a crowded street, a crowded indoor or outdoor area or the like to provide people speech guidance. Also, a touchscreen with a touch panel such as a tablet computer may be mounted on the inner side of the sound absorbing unit of the mobile terminal booth (for example, the inner surface of the arch-like connector  440  shown in  FIG. 20 ) to provide speech guidance together with visual guidance. Furthermore, if an Internet connectivity function and a stationary videophone system are implemented in the touchscreen, it is possible to have a video teleconference. 
     In accordance with the mobile terminal booth of the present invention, a space suitable for using mobile terminals can be provided to raise convenience of users of mobile terminals. For example, if the mobile terminal booth is installed in a lobby of a hotel, guests can comfortably use mobile terminals, and manners are improved to make better the atmosphere in the hotel. Furthermore, the outer side of the sound absorbing unit may be used as an advertising space so that certain earnings can be expected. For example, a speaker is installed in the mobile terminal booth for running an audio commercial. This audio commercial may always be running, but halted a predetermined period after detecting a user who enters the mobile terminal booth by a human sensor in order not to hinder conversation. This predetermined period is no longer than thirty seconds, for example, three seconds to twenty seconds, preferably five seconds to ten seconds. When the user exits the mobile terminal booth, the audio commercial resumes. Music may be associated with this commercial. 
     In accordance with the mobile terminal booth of the present invention, the sound absorbing unit partially confines and provide a private space where a mobile terminal can be used in a comfortable manner. The mobile terminal booth consists mainly of a sound absorbing unit confining a private space with an entrance opening, so that users do not feel suffocated in a narrow space with unpleasant reverberating sound and can have telephone conversations with comfort and less stress. Furthermore, the voice does not leak in the backward and lateral directions beyond the sound absorbing unit, and is absorbed in the mobile terminal booth without being reflected in the forward direction. Accordingly, the user need hardly worry about others who may hear conversation, and cause a nuisance to others nearby even if speaking loudly. On the other hand, the person at the other end of conversation can hear the voice clearly without reflection noise. 
     The foregoing description of the embodiments has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form described, and obviously many modifications and variations are possible in light of the above teaching. The embodiment was chosen in order to explain most clearly the principles of the invention and its practical application thereby to enable others in the art to utilize most effectively the invention in various embodiments and with various modifications as are suited to the particular use contemplated.