Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B06—GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS IN GENERAL
  • B06B—METHODS OR APPARATUS FOR GENERATING OR TRANSMITTING MECHANICAL VIBRATIONS OF INFRASONIC, SONIC, OR ULTRASONIC FREQUENCY, e.g. FOR PERFORMING MECHANICAL WORK IN GENERAL
  • B06B1/00—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency
  • B06B1/02—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy
  • B06B1/06—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction
  • B06B1/0603—Methods or apparatus for generating mechanical vibrations of infrasonic, sonic, or ultrasonic frequency making use of electrical energy operating with piezoelectric effect or with electrostriction using a piezoelectric bender, e.g. bimorph
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R17/00—Piezoelectric transducers; Electrostrictive transducers
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R7/00—Diaphragms for electromechanical transducers; Cones
  • H04R7/02—Diaphragms for electromechanical transducers; Cones characterised by the construction
  • H04R7/04—Plane diaphragms
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04R—LOUDSPEAKERS, MICROPHONES, GRAMOPHONE PICK-UPS OR LIKE ACOUSTIC ELECTROMECHANICAL TRANSDUCERS; DEAF-AID SETS; PUBLIC ADDRESS SYSTEMS
  • H04R2400/00—Loudspeakers

Definitions

• the present invention relates to a piezoelectric vibrator used in a piezoelectric panel speaker and the like.
• the invention relates to such a piezoelectric vibrator with two or more multi acting vibrators, in which plural piezoelectric members, to which different electrical signals having different frequency bands are applied independently, are used and the geometrical structure of an elastic member attached to the piezoelectric member is especially designed, thereby obtaining a high sound pressure over the whole sound range, along with a stereo sound effect.
• the invention also relates to a simple structured panel speaker using the piezoelectric vibrator.
• U.S Patent No. 4,593,160 discloses a piezoelectric vibrator using a bimorph type rectangular actuator.
• U.S. Patent No. 5,632,841 discloses a method of fabricating an actuator by attaching a ferroelectric wafer to a stressed elastic body.
• plural vibrators are disposed, or a mass body is mounted on the rear of the piezoelectric body in order to vary the vibration pattern thereof, or the like.
• all these methods are not a practical and effective solution to increase the sound pressure of a piezoelectric speaker, also.
• the present invention has been made in order to solve the above problems occurring in the art, and it is an object of the invention to provide a piezoelectric vibrator, in which a high and uniform sound pressure can be achieved over the whole sound range, along with the stereo sound effect thereof.
• Another object of the invention is to provide a piezoelectric panel speaker, in which a stereo sound effect can be achieved using a simple structure where a single piezoelectric vibrator is mounted on a single panel.
• a piezoelectric vibrator comprising: a multi-acting vibrator for converting electrical signal into mechanical vibration including an elastic member, and a plurality of piezoelectric members each of which is attached to one face of the elastic member and have electrodes attached to both faces thereof; and a vibration transmission elastic member attached to the elastic member of the multi-acting vibrator, for transmitting the mechanical vibration to the outside, wherein electrical signals of different frequency bands are applied independently to each of the plural piezoelectric members constituting the multi-acting vibrator.
• the axial cross-section of the entire piezoelectric vibrator may has an asymmetric I-shape for enhancing sound pressure transformed from electric signal.
• the multi-acting vibrator may include further vibration control elastic member attached to the other face of the piezoelectric member and for controlling vibration pattern of the piezoelectric member.
• the multi-acting vibrator may further include a plurality of other piezoelectric members in the other face of the elastic member, correspondingly to the plurality of piezoelectric members.
• the elastic member of the piezoelectric vibrator is formed of a metal, or may be formed of an organic or inorganic polymer material having a young's modulus of more than lOGpa.
• the plural of piezoelectric members are attached to the vibration transmission elastic member and the vibration control elastic member using an epoxy.
• the piezoelectric member is formed of a polycrystalline ceramics of PZT (lead-zirconium titanate series material), or formed of a ferroelectric single crystal material, which is one selected from the group consisting of PMN-PT (Lead Magnesium Niobate - lead titanate series material), PZN-PT (Lead Zinc Niobate - lead titanate series material), PZT (Lead Zirconium titanate series material), PYN-PT (Lead Ytterbium Niobate - lead titanate series material and PIN-PT (Lead Indium Niobate - lead titanate series material), which has a composition satisfying either one of the following chemical formulas 1 and 2; wherein the chemical formula 1 is s[L]-x[P]y[M]z[N]p[T], where [P] is PbO, PbO , and Pb O , [M] is MgO or
• the piezoelectric material has a single layered or multi-layered structure, wherein the multi-layered structure may be formed of layers having a same area and shape or having an area and shape different from each other. [15] And, the piezoelectric material may be one of the forms of a bulk and a thin film made of a single crystal or a polycrystalline material. [16] Finally, there is provided a piezoelectric panel speaker having a piezoelectric vibrator according to the present invention.
• the piezoelectric member is not directly connected to the vibration transmission elastic member and thus a failure of the piezoelectric member due to an external impact and a fatigue caused by a longtime service can be prevented.
• Plural piezoelectric members are used, each of which is operated independently by a different electrical signal. Therefore, by using a single piezoelectric vibrator, a uniform high sound pressure can be generated over the whole sound range of high to low sound, along with an adequate stereo sound effect.
• the piezoelectric vibrator of the invention has a simplified structure so that the manufacturing process can be significantly simplified and the energy efficiency for the consumed electric power can be greatly improved. Therefore, electric energy can be saved, miniaturization of the product can be achieved, and the signal distortion caused by noise can be alleviated.
• the requirements for the vibrating plate is not very restrictive and thus it can be accomplished in the form capable of being used in water or humid environment.
• FIG. 1 is a vertical cross-section and bottom view of a conventional piezoelectric vibrator
• FIG. 2 is a vertical cross-section and bottom view of a piezoelectric vibrator according to one embodiment of the invention
• FIG. 3 is a graph comparing the sound pressure generated by the piezoelectric vibrator of the invention shown in FIG. 2 with that of the conventional one shown in
• FIG. 7(a) to 7(e) are plan views of piezoelectric vibrator s according to another embodiment of the invention, where the number, shape, and cross-sectional area of the piezoelectric member are varied; and [29] FIG. 8 is a vertical cross-section and bottom view of a piezoelectric vibrator according to another embodiment of the invention, where plural piezoelectric members having different areas are formed in a multi-layered configuration.
• FIG. 1 is a vertical cross-section and bottom view of a piezoelectric vibrator having an asymmetric I-shape, which is disclosed in Korean Patent Application No.
• the cross sectional area is decreased, from a piezoelectric actuator 11 for generating vibration, towards a first portion 12a of an electric member for transmitting vibration, thereby enabling to increase the amplitude of vibration.
• This type of piezoelectric vibrator can produce a high sound pressure, as compared with other conventional ones.
• plural piezoelectric vibrators must be attached to the speaker panel in order to obtain a stereo sound effect. Therefore, the configuration thereof is complicated or the amount of materials to be used is increased, thereby increasing the price of end-products.
• FlG. 2 is a vertical cross-section and bottom view of a piezoelectric vibrator 100 according to one embodiment of the invention.
• the piezoelectric vibrator of the invention is formed of a simpler structure, which includes a multi-acting vibrator 110 for converting an electrical signal into a mechanical vibration, and a vibration transmission elastic member 120 for transmitting the mechanical vibration into outside.
• the piezoelectric vibrator 100 of the invention has in general an English letter I-shape in the cross-section taken along the axial direction of the whole vibration transmission elastic member 120 and the multi-acting vibrator 110.
• This structure is favorable for obtaining a high sound pressure. Therefore, the area of the cross-section is decreased toward a first portion 120a of the vibration transmission elastic member, thereby achieving an effect of increasing the amplitude of vibration.
• the multi-acting vibrator 110 is formed of a piezoelectric member 110a, 110a and an elastic member 110b attached to the piezoelectric member.
• the piezoelectric member is provided with an electrode for receiving an electrical signal from the outside, but not this electrode is illustrated in the accompanying drawings, for the purpose of clearly explaining the structural features of the piezoelectric vibrator according to invention.
• the electrode may be implemented by the well-known art in the field of the present invention.
• the piezoelectric vibrator of the invention is provided with a plurality of piezoelectric members 110a, 110a formed detached from each other, and each piezoelectric member is to receive independently an electrical signal of frequency band different from each other. Therefore, different members can generate different sound having different ranges, thereby generating a stereo sound using a single vibrator.
• a high frequency signal is applied to one piezoelectric member 110a and a low frequency signal is applied independently to the other one 110a so that a high sound pressure can be obtained over the whole sound range.
• FIG. 3 is a graph comparing the sound pressure generated by the piezoelectric vibrator of the invention with that of the conventional one shown in FlG. 1 by the Korean Patent Application No. 2004-70101. It can be seen from FlG. 3 that the piezoelectric vibrator having the multi-acting vibrator 110 of the invention exhibits an improved sound pressure by more than 15dB over the whole sound range, as compared with the conventional one in the previous Patent Application.
• a new structure of the multi-acting vibrator 110 in which the elastic member 110b is formed of two piezoelectric members 110a, 110a detached from each other is employed instead of bimorph actuator; thereby the piezoelectric member can be prevented from being broken down by an external impact or a long- term service.
• FlG. 4 is a plan view and a side view of a piezoelectric panel speaker having the piezoelectric vibrator of FlG. 2.
• the piezoelectric vibrator 100 is mounted on the prescribed edge region of the vibration panel 200.
• vibration generated from the multi-acting vibrator 110 is transmitted to a vibration panel 200 via each portion 120a, 120b of the vibration transmission elastic member 120 and the sound is output to the outside.
• Due to its geometrical features of the structure of the piezoelectric vibrator 100 according to the invention it can produce a sound pressure significantly higher than that of the conventional ones.
• the simple structured vibrator 100 where a single piezoelectric vibrator is mounted on a single panel, can achieve a stereo sound, dissimilar to the one in the previous Korean Patent application No. 2004-70101.
• FlG. 5 is a vertical cross-section and bottom view of a piezoelectric vibrator according to another embodiment of the invention, where an elastic member for controlling vibration is provided.
• the piezoelectric vibrator 100 of this embodiment includes a vibration control elastic member 130 formed on the other side of the piezoelectric member, separately from the vibration transmission elastic member 120.
• the vibration control elastic member 130 is attached to the opposite side to the vibration transmission elastic member 120 with respect to the multi-acting vibrator 110 so as to function to control the magnitude of the vibration generated by the multi-acting vibrator 110 and the wavelength produced by a maximum sound pressure.
• FlG. 6 is a vertical cross-section and bottom view of a piezoelectric vibrator according to another embodiment of the invention, where the multi-acting vibrator 110 is formed symmetrically about the elastic member 110b.
• the piezoelectric member 110a is formed on only one side of the elastic member HOb
• the piezoelectric vibrator 100 of this embodiment is provided with a further piezoelectric member 110a"formed symmetrically about the elastic member 110b than, thereby enabling to produce a higher mechanical vibration signal or sound pressure.
• an additional vibration controlling member 130' may be attached to the piezoelectric member HOa".
• FIGS. 7(a) to 7(e) are plan views of piezoelectric vibrators according to other em- bodiments of the invention, where the number, shape, and cross-sectional area of the piezoelectric member are varied.
• the embodiment of FlG. 2 proposes that the number of independent piezoelectric member is two, and the multi-acting vibrator and the piezoelectric member have a rectangular shape, it is noted that the number and shape of the piezoelectric member can be varied appropriately, depending on the shape of a vibration panel on which the piezoelectric vibrator is mounted, and the desired frequency band.
• the thickness, the polygonal shape and size, and the center of gravity of the multi-acting vibrator 110 and the elastic member 120, 130 can be adjusted appropriately, depending on its applications.
• FlG. 8 is a vertical cross-section and bottom view of a piezoelectric vibrator according to another embodiment of the invention, where plural piezoelectric members having different areas are stacked in a multi-layered configuration.
• the characteristics of the generated sound and frequency can be controlled by changing the area and shape of each layer of the piezoelectric members.
• the elastic member is preferred to be formed of a metallic material such as steel, aluminum alloys or the like.
• a polymer material having a high Young's modulus, preferably more than lOGpa, may be used.
• the polymer material includes an organic or inorganic polymer, or a mixture thereof, but not particularly limited thereto.
• an adhesive such as epoxy, which has a high hardness after cured, is preferred, in order to minimize a signal attenuation phenomenon.
• the piezoelectric member 110a is preferred to be formed of a polycrystalline ceramics of PZT (lead-zinc titanate series material), which are commonly used in the art, or a piezoelectric single crystal ceramics having a good piezoelectric property.
• PZT lead-zinc titanate series material
• the ferroelectric single crystal substance suitable to be used in the invention includes PMN-PT (Lead Magnesium Niobate - lead titanate series material), PZN-PT (Lead Zinc Niobate - lead titanate series material), PZT (Lead Zirconium titanate series material), PYN-PT (Lead Ytterbium Niobate - lead titanate series material and PIN-PT (Lead Indium Niobate - lead titanate series material).
• PMN-PT Lead Magnesium Niobate - lead titanate series material
• PZN-PT Lead Zinc Niobate - lead titanate series material
• PZT Lead Zirconium titanate series material
• PYN-PT Lead Ytterbium Niobate - lead titanate series material
• PIN-PT Lead Indium Niobate - lead titanate series material
• the ferroelectric single crystal substance is preferred to satisfy the composition of either one of the following chemical formulas 1 and 2. [50] [Chemical formula 1]
• [P] is PbO, PbO 2 , and Pb 3 O 4
• [M] is MgO or ZnO
• [N] is Nb 2 O 5
• [T] is TiO 2
• [L] is LiTaO , LiNbO , Li, Li O or Li CO , or one metal or its oxide selected from the
• x is more than or equal to 0.55 and less than or equal to 0.65
• y is more than or equal to 0.09 and less than or equal to 0.20
• z is more than or equal to 0.09 and less than or equal to 0.20
• p is more than or equal to 0.01 and less than or equal to 0.1
• s is more than or equal to 0.01 and less than or equal to 0.1.
• x is equal to zero or more than 0.01 and less than 0.2
• y is more than 0.1 and less than 0.4
• Z is more than 0.4 and less than 0.6
• 1 is more than 0.2 and less than 0.8
• m is more than 0.2 and less than 0.8.
• the single crystalline materials having the above compositions may be manufactured using the method disclosed in Korean Patent Application No. 2003-47458 filed in the named of the assignor, IBULE PHOTONICS CO., LTD.
• the disclosure of the above patent Korean Patent application No. 2003-47458 is also incorporated by reference into the present application.
• the single crystal material having the above chemical formulas 1 and 2 has a piezoelectric stain constant higher than the conventional PZT ceramics or poly- crystalline thin film, and thus performs a greater strain in response to the same electrical signal applied thereto, as compared with the conventional ones. Therefore, when it is applied to a piezoelectric vibrator, preferably it can generate a higher sound pressure by converting the electrical signal into a sound signal. Furthermore, since it has a higher piezoelectric voltage constant, it can generate a higher output voltage when an external stress such as a sound signal is exerted. Also, it has a high electrical- mechanical coupling coefficient; advantageously it has high-energy conversion effici ency for a consumed electric energy. In addition, the atoms or molecules are regularly close-packed in a given space in case of a single crystal material, and thus a fine machining can be carried out on it.
• Table 1 represents the actual measurement values, which was measured using a resonant measurement in accordance with IEEE (Institute of Electrical and Electronics Engineers) standard.
• LVDT Linear Variable Differential Transformer
• d is the piezoelectric strain constant in the thickness mode
• k is the electrical-mechanical coupling coefficient in the thickness mode
• g is the piezoelectric voltage constant in the thickness mode.
• S is the strain rate
• L is the initial length [m]
• ⁇ L is the amount of de- formation [m]
• E is the intensity of electric field [V/m]
• d is the piezoelectric strain constant.
• the piezoelectric strain constant d of the PMN-PT single crystal is about above 70 times of the PVDF and about above 4 times of the conventional PZT ceramics. Therefore, according to the invention, the piezoelectric vibrator using the PMN-PT single crystal can increase the sound pressure more than 4-70 times with respect to the same input voltage, as compared with the conventional ones using the PVDF or PZT ceramics and having the same specification. In other words, the piezoelectric vibrator of the invention can obtain the same magnitude of sound pressure using a 1/70-1/4 times voltage, as compared with the conventional ones. Therefore, it can be applied advantageously to mobile devices requiring low energy consumption and miniaturization.
• the PMN-PT single crystal used in the piezoelectric vibrator according to the invention has a high electrical-mechanical coupling coefficient and thus high energy efficiency for the consumed electric energy, as compared with the conventional PVDF polymer and PZT ceramics. Therefore, a piezoelectric vibrator consuming less energy can be achieved, along with the miniaturization thereof, and also the signal distortion due to noise can be reduced.
• the single crystal of the above piezoelectric member 110a may is structured in the form of a bulk or a film, and may have a single layered or multi-layered structure.
• a bulk form of piezoelectric single crystal material is ground in the form of a thin film, which then is attached to an electrode.
• the bulk form may be attached to an electrode and then ground into the form of a thin film.
• the thin film of piezoelectric single crystal enables a reduction in the entire thickness of the piezoelectric member 110.

Landscapes

• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Acoustics & Sound (AREA)
• Signal Processing (AREA)
• Mechanical Engineering (AREA)
• Piezo-Electric Transducers For Audible Bands (AREA)
• Multimedia (AREA)

Priority Applications (2)

Applications Claiming Priority (2)

Publications (1)

Family

ID=36565272

Family Applications (1)

Country Status (4)

Cited By (4)

Families Citing this family (12)

Citations (3)

Family Cites Families (7)

• 2004
  • 2004-12-03 KR KR1020040100886A patent/KR100625772B1/ko not_active IP Right Cessation
• 2005
  • 2005-11-29 JP JP2007544261A patent/JP4758998B2/ja not_active Expired - Fee Related
  • 2005-11-29 WO PCT/KR2005/004035 patent/WO2006059856A1/en active Application Filing
  • 2005-11-29 CN CN2005800414561A patent/CN101069341B/zh not_active Expired - Fee Related

Patent Citations (3)

Also Published As

Similar Documents

Legal Events