Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R9/00—Transducers of moving-coil, moving-strip, or moving-wire type
  • H04R9/06—Loudspeakers

Definitions

• the present invention relates to a sound reproduction transducer connected to a printed circuit and a terminal comprising a transducer.
• One of the non-exclusive fields of application of the invention is that of mobile radiocommunication terminals. Manufacturers of mobile communication terminals are currently seeking to miniaturize them as much as possible while retaining optimal functional ergonomics. This optimization of the size of the terminals, a diagram of which in side view is proposed in FIG. 1, prompted the manufacturers to reduce their thickness.
• a mobile terminal comprises a box 10 in which various components are arranged such as a battery 20, a keyboard 30, a screen 40 and a sound reproduction transducer 60 connected to a printed circuit 50.
• the sound reproduction transducer or sound transducer 60 is capable of transforming the electrical signals supplied to it into acoustic waves and vice versa.
• the sound transducer 60 can fulfill several functions such as that of the earpiece, loudspeaker, buzzer and vibrator.
• the earpiece is essentially intended to be placed against the ear of a user when using the device in communication, the ring allows to alert the user of an incoming call or any other action , the loudspeaker allows a high volume sound reproduction for hands-free applications, or ringtones for example, and the vibrator allows the user to discreetly warn the user of an incoming call by vibration e the earpiece,
• the sound transducer 60 consists of two separate volumes defining a front acoustic cavity 61 and a rear acoustic cavity 62, the shapes and dimensions of which must be adapted to make a sound reproduction of sufficient quality for the application for which the transducer is intended.
• the headphone function requires a component size smaller than that required for a high function. -speaker and bell ringing which must emit a greater volume. The volume occupied by the sound transducer 60 cannot therefore be reduced beyond a certain limit imposed by the loudspeaker function,
• the current trend is to reduce the size and in particular the thickness of the terminals.
• the rear acoustic cavity 62 of the sound transducer 60 of the current terminals has an unsatisfactory size and the space between the rear face of the transducer and the printed circuit is too small to allow sound reproduction of sufficient quality.
• the space between the rear face of the transducer and the impnammed circuit has a thickness of less than 1 mm, there is an untimely damping of the vibrations in the diaphragm of the sound transducer 60. These vibrations serving to generate the sounds, it s 'follows a sound reproduction of insufficient quality.
• the object of the invention is to propose a sound transducer having a satisfactory sound reproduction quality although its rear face is very close to another component of the terminal.
• the invention for this purpose relates to a sound reproduction transducer connected to a printed circuit, the transducer having the shape of a hollow cylinder, the cylindrical wall of which delimits two circular faces, one (ace front and one opposite rear face and flat, the transducer comprising at least one diaphragm making it possible to convert electrical signals into acoustic waves and vice versa, the diaphragm being a membrane, circular parallel to the front and rear faces of the transducer, the diaphragm delimiting two distinct volumes in the transducer.
• first volume bordered on one side by the circular face of the transducer and on the other by the diaphragm, being a front acoustic cavity
• second volume bordered on one side by the circular face of the transducer and on the other by the diaphragm, being a rear acoustic cavity, characterized in that said cylindrical wall of the transducer has at least one perforation.
• the invention makes it possible to facilitate the rear air flow from the sound transducer and therefore to allow acoustically satisfactory use of the transducer
• the perforation forms a hole in the rear acouslic cavity of the transducer
• said circular face of the transducer has at least one perforation
• the invention also relates to a radiocommunication terminal comprising a sound reproduction transducer, as just defined
• a radiocommunication terminal comprising a sound reproduction transducer, as just defined
• FIG. 1 already described, illustrates a schematic cross-sectional view of a radiocommunication terminal showing the main components.
• FIG. 2 illustrates an exploded view in three dimensions of the sound transducer according to the invention comprised between the printed circuit and the terminal box.
• FIG. 3 represents a sound transducer seen in longitudinal section along ll of FIG. 2.
• radio transceivers such as, for example, a radio messaging device, a personal digital assistant (personal digital assistant or PDA in English) or portable computers.
• a radio messaging device such as, for example, a radio messaging device, a personal digital assistant (personal digital assistant or PDA in English) or portable computers.
• PDA personal digital assistant
• the transducer 60 has a general shape of a hollow cylinder, the cylindrical outer wall 66 of which is delimited by two circular faces opposite one another: a front face ⁇ c, and a rear face ⁇ d substantially planar s. These faces ⁇ c, ⁇ d are substantially parallel to each other.
• the front circular face ⁇ c represents the front face 63a of the transducer 60.
• the rear circular face ⁇ d represents the rear face 63b of the transducer 60.
• the diaphragm 64 of the transducer 60 is located between the two circular faces front ⁇ c and rear ⁇ d and substantially parallel 6 these, about half the height of the outer wall of the transducer 60.
• the rear acoustic cavity 62 defined between the rear circular face ⁇ d and the diaphragm 64 usually has perforations 70a, 70b, 70c located on the rear face ⁇ d.
• These perforations 70a, 70b, 70c can be of various shape and size.
• a substantially round perforation 70b is located in the center of the rear circular face ⁇ d and its radius is approximately one third of the radius of the rear circular face ⁇ d.
• Perforations, substantially round, 70a and 70c are located towards the periphery of the circular face ⁇ d and their radius is approximately one tenth of the radius of the circular face ⁇ d. Thus, air can escape through these perforations towards the rear of the transducer 60.
• the transducer 60 according to the invention has a perforated cylindrical wall 69a, 69b.
• the cylindrical wall 69a, 69b of the transducer 60 has perforations 72, 74, 76, 77, 78.
• the perforations 72, 74, / 6, 77, 78 are of substantially rectangular shape. Their size is approximately one third of the height of the cylindrical wall 69a, 69b.
• the substantially rectangular perforations 72, 74, 76, 77, 78 are located near the junction between the cylindrical wall ⁇ and the front circular face ⁇ c, at a distance of about one twentieth of the height of the cylindrical wall 66 from the front circular face ⁇ c.
• a transducer 60 comprises a diaphragm ⁇ 4 delimiting two cavllies in the transducer 60: a front cavity 61 and a rear cavity 62, of a coil 67, a magnet 68, a metal support 69 , such as a cylinder head, comprising a magnetic circuit 69a and a weight 69b.
• the coil 67, the magnet 68, the metal support 69 are located in the front cavity 61, therefore between the diaphragm 64 and the front circular face 66c of the transducer 60,
• the transducer 60 consists of two parts, a first electrically neutral part including the diaphragm 64 and the cylindrical wall ⁇ made of dielectric materials such as plastics for example; and a second electrically conductive part including the coil 67, the magnet 68 and the metal support 69 made of conductive materials,
• the front acoustic cavity 61 is bordered on one side by the front circular face ⁇ c of the transducer 60 and on the other by the diaphragm 64.
• the rear acoustic cavity 62 is bordered on one side by the rear circular face ⁇ d of the transducer 60 and on the other by the diaphragm 64.
• the diaphragm 64 is a substantially circular membrane parallel to the two front and rear circular faces ⁇ c and ⁇ d.
• the diaphragm 64 is fixed all along its perimeter on the internal face of the cylindrical wall 66.
• the diaphragm 64 is also fixed on the coil 67 all along the inside perimeter of the coil 67,
• the diaphragm 64 has its center substantially at the middle of the transducer generator 60.
• the coil 67 as known in the prior art, is substantially in the shape of a hollow cylinder composed of two substantially circular disc and a cylindrical wall. Its generator is located on the generator of the cylindrical transducer 60 and its center substantially in the middle of the generator of the transducer 60. Its discs are substantially parallel to the circular faces 6 ⁇ c or ⁇ d.
• Its radius has a dimension of approximately half the radius of one of the circular faces ⁇ c or ⁇ d,
• the coil 67 is fixed all along the perimeter of one of its discs on the magnetic circuit 69a and the other disc is fixed on the diaphragm 64.
• the magnet 68 is substantially in the form of a full cylinder. Its circular faces are substantially parallel to the circular faces ⁇ c or ⁇ d. Its generator is located on the generator of the cylindrical transducer 60 and its center is substantially in the middle of the generator of the transducer 60. Its radius is slightly smaller than that of the coil 67.
• One of the circular faces of the magnet 68 is fixed to the magnetic circuit 69a. The magnet 68 and the coil 67 are embedded in the magnetic circuit 69a.
• the magnetic circuit 69a is in the general form of a hollow cylinder with a wide edge composed of a substantially circular face and a ring parallel to the circular face and a thick cylindrical wall. Its circular face and its crown are substantially parallel to the circular faces ⁇ c or ⁇ d of the transducer 60. Its generatrix is located on the generatrix of the cylindrical transducer 60 and its center substantially in the middle of the generatrix of the transducer 60. Its radius has a dimension slightly more significant of that of the coil 67.
• the weight 69b as known in the prior art, is substantially the same shape as the magnetic circuit 69a and the magnetic circuit 69 is embedded in this weight 69b. Its radius has a slightly larger dimension than that of the magnetic circuit 69a, Its cylindrical wall is fixed by suspensions 65 to the cylindrical wall 66 of the transducer 60.
• the suspensions 65 are fixed, on the one hand in the middle of the cylindrical wall of the metal support 69 and perpendicular to the latter, and on the other hand, fixed perpendicular to the external face of the cylindrical wall 66 of the transducer 60.
• the suspensions 65 are for example springs extending parallel to the circular faces ⁇ c and ⁇ d of the transducer 60.
• the suspensions 65 connected to the weight 69b form a weight-suspension system which is vibrated when the coil 67 is excited by an electric current.
• the invention therefore allows acoustically satisfactory use of the transducer 60 under critical conditions of space between the various components of the radiocommunication terminal.

Landscapes

• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• Audible-Bandwidth Dynamoelectric Transducers Other Than Pickups (AREA)
• Telephone Set Structure (AREA)
• Diaphragms For Electromechanical Transducers (AREA)
• Details Of Audible-Bandwidth Transducers (AREA)
• Piezo-Electric Transducers For Audible Bands (AREA)
• Electrostatic, Electromagnetic, Magneto- Strictive, And Variable-Resistance Transducers (AREA)

Applications Claiming Priority (2)

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• 2003
  • 2003-07-25 FR FR0309112A patent/FR2858164B1/fr not_active Expired - Fee Related
• 2004
  • 2004-07-19 US US10/565,472 patent/US7408444B2/en not_active Expired - Fee Related
  • 2004-07-19 RU RU2006105651/28A patent/RU2347326C2/ru not_active IP Right Cessation
  • 2004-07-19 CN CN2004800276891A patent/CN101151937B/zh not_active Expired - Fee Related
  • 2004-07-19 WO PCT/FR2004/001939 patent/WO2005020623A2/fr active Application Filing
  • 2004-07-19 EP EP04767745A patent/EP1665870A2/fr not_active Withdrawn
  • 2004-07-19 CA CA2533290A patent/CA2533290C/en not_active Expired - Fee Related

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