JP5070164B2 - Acoustic signal generator - Google Patents

Description

  The present invention relates to an acoustic signal generating apparatus that allows a user to recognize sound by converting a sound electric signal into acoustic vibration and transmitting the sound vibration signal to a hearing organ.

  In recent years, with the rapid spread of mobile phones and portable music devices, there has been a demand for improvements in call quality in calls in a noisy environment, volume and sound quality in listening to music on a train. As a technique for solving these problems, an acoustic signal generating device called a bone conduction speaker has attracted attention.

  The bone conduction speaker converts sound information (speech and music information) into mechanical vibration and transmits the sound information to the auditory nerve via the bone of the head. Since the user can recognize the sound information by bringing the mechanically vibrating part of the bone conduction speaker into contact with the bone of the head, the bone conduction speaker can be used even in a situation where the sound is difficult to hear, for example, in a noise environment. Sound information can be transmitted by using.

  When a bone conduction speaker is used as a receiver of a mobile phone or the like, the volume, sound quality, echo performance (leakage from the speaker into the microphone), etc. when incorporated in the device are important. In particular, echo performance is a very important item related to call quality in mobile phones and the like.

  As a bone conduction speaker suitable for the above-mentioned performance, Patent Document 1 proposes an acoustic signal generator having a displacement magnifying mechanism composed of a substantially U-shaped main structure. FIG. 4 is a cross-sectional view of a conventional acoustic signal generator. The expansion lever 1, which is the main structure of the displacement expansion mechanism, is formed by press forming a steel plate suitable for mass production. A laminated piezoelectric element 2 to which an input line 2a is connected is installed between the upper and lower sides facing the U-shape, that is, between the enlarged lever output portion 1b that is the upper side and the enlarged lever base portion 1a that is the lower side. ing. The laminated piezoelectric element 2 is displaced in the laminating direction (longitudinal direction) and has an U-shaped open end, that is, an enlarged lever elastic portion that elastically couples the enlarged lever output portion 1b and the enlarged lever base portion 1a. The side facing 1c is displaced so as to open and close relatively. This displacement is magnified by the lever principle, and a large displacement is obtained on the tip side.

  The magnifying lever output part 1b and the magnifying lever base part 1a have higher rigidity than the magnifying lever elastic part 1c which is a U-shaped vertical side connecting them. A weight 3, which is a molded product of a metal material having a large specific gravity, is attached to the enlarged lever base portion 1 a by a fixing screw 4.

  On the other hand, a pad 6 of a plastic molded product is bonded and fixed to the upper surface of the enlarged lever output portion 1b. The mass of the output portion made up of the enlarged lever output portion 1b and the pad 6 is smaller than the mass of the base portion made up of the enlarged lever base portion 1a and the weight 3. Therefore, when the laminated piezoelectric element 2 is displaced, the expansion lever elastic portion 1c becomes an elastic deformation portion that generates a role of a hinge and a return force with respect to the rotational displacement of the base portion and the output portion.

  At this time, since the mass of the output part is smaller than the mass of the base part, the rotational displacement of the output part is larger than the rotational displacement of the base part. When the upper surface of the output unit, that is, the upper surface of the pad 6 is brought into contact with the user's head, the enlarged displacement is transmitted to the user. That is, in the above configuration, when an acoustic signal is applied to the multilayer piezoelectric element 2, the displacement enlarging mechanism expands the displacement of the multilayer piezoelectric element 2 and transmits the expanded displacement to the pad 6 of the expansion lever output unit 1b. To do. By bringing the pad 6 into contact with the head, mechanical vibration propagates through the auditory nerve, and the user can recognize the bone conduction sound.

  However, if a user who does not know how to use the bone conduction speaker does not contact the pad portion with the head, the vibration of the output portion is not transmitted to the head. That is, there is a problem that sound information is not recognized by the user.

  In addition, with the downsizing of mobile phones and portable music devices, acoustic signal generators are also required to be further downsized and improved in performance, so a structure with a simpler configuration and greater output is required. It has been.

JP 2007-74663 A

  The problem to be solved by the present invention is a configuration having functions that can be used in the same manner in both modes of use when the output unit is in contact with the head and when not in contact with the head, in other words, a bone. An object of the present invention is to provide an acoustic signal generator having a compact configuration, which has both a conduction function and an air conduction function.

  According to the present invention, a stacked piezoelectric element that mechanically vibrates by expanding and contracting in response to an applied electric signal, a receiving surface that receives expansion and contraction of the stacked piezoelectric element, and the stacked piezoelectric element are supported. An acoustic signal generating device including a weight including a support portion, an enlargement lever for enlarging and outputting the mechanical vibration generated by the multilayer piezoelectric element, and a rigid pad at the output portion of the enlargement lever is obtained.

  Here, the pad is composed of a projecting portion whose one end is closed and a flange portion provided around the open end surface of the projecting portion, and the edge of the flange portion is disposed between the tip of the projecting portion and the open end surface. ing. Also, if the flange has rigidity enough to withstand the displacement of air and the mass is sufficiently small, the edge has an opening on the open end face side even if the edge has an opening on the tip end side of the protrusion. It doesn't matter.

  In the present invention, the rigidity of the frame structure portion formed by the weight receiving surface and the support portion and the rigidity of the base portion are sufficiently higher than the bending rigidity of the enlarged lever bending portion. Therefore, the rotational displacement corresponding to the expansion / contraction displacement of the laminated piezoelectric element is output to the enlargement lever output part, the pad protrusion, and the flange part with the enlargement lever bent part as the rotation center. In addition, the movable lever driving portion, the expanding lever output portion, the movable portion including the pad, and the fixed portion including the expanding lever base portion and the weight are centered on the expanding lever bending portion serving as the rotation center. Is displaced (rotated and displaced) in the direction of opening and closing.

  At this time, since the mass of the fixed part is sufficiently larger than the mass of the movable part, the movable part is mainly displaced. In other words, the movable portion and the fixed portion are displaced in inverse proportion to the ratio of the moment of inertia of the movable portion and the moment of inertia of the fixed portion, with the enlarged lever bent portion being the center of rotation as the center. Therefore, in order to suppress the movement of the fixing portion, the mass of the fixing portion may be increased, or the center of gravity of the fixing portion may be arranged at a position away from the bent portion that is the rotation center. Similarly, the mass of the movable part may be reduced, or the center of gravity of the movable part may be brought closer to the enlarged lever bent part.

  Further, the weight of the fixed portion is arranged at a position farthest from the enlarged lever bent portion at the rotation center. Further, since the preload screw is mounted in the longitudinal direction from the end of the weight, the portion having the largest mass is disposed at a position away from the rotation center. Therefore, the center of gravity of the fixed portion is located away from the magnifying lever bent portion. On the other hand, the movable part makes the center of gravity of the movable part closer to the bent part by narrowing the tip of the rib. Since the mass of the movable part can be made sufficiently smaller than the mass of the fixed part, the displacement of the fixed part can be suppressed. With the above configuration, the effect of the moment of inertia of the movable part and the fixed part can be expected.

  According to the present invention, the configuration having a function capable of recognizing sound information in both of the usage forms when the protrusion of the pad is brought into contact with the head and when not in contact with the head, in other words, the bone conduction function. An acoustic signal generator with a compact structure having an air conduction function can be obtained. Therefore, the user can selectively use the bone conduction function in a noisy environment and the air conduction function in a quiet environment. Therefore, a product employing this apparatus has an effect of enhancing its product function.

  Hereinafter, the present invention will be described in detail with reference to FIGS. 1 to 3.

  FIG. 1 is an exploded perspective view in which an acoustic signal generator using the present invention is developed into parts, and FIG. 2 is a cross-sectional view of the acoustic signal generator using the present invention cut at the center. FIG. 3 is a side view of another embodiment of the pad.

  As shown in FIGS. 1 and 2, the acoustic signal generator of the present invention includes an expansion lever 10, a laminated piezoelectric element 2, a weight 30, a fixing screw 40, a pad 60, and a preload screw 50.

  The laminated piezoelectric element 2 is formed by alternately laminating sheet-like piezoelectric materials and electrode materials, and the length changes in the laminating direction. Since the present invention relates to the application of the multilayer piezoelectric element 2, the details of the multilayer piezoelectric element 2 are omitted.

  The laminated piezoelectric element 2 is disposed along the support portion 31 of the weight 30, and the expansion lever 10 is attached so as to cover the support portion 31 and the laminated piezoelectric element 2. At this time, the input line of the multilayer piezoelectric element 2 passes through the two holes 35 in the base portion of the support portion 31 and is connected to an external drive circuit (not shown).

  The weight 30 and the expansion lever 10 are fixed at a predetermined position by tightening the fixing screw 40 inserted into the screw hole 32 of the support portion 31 through the hole 16 of the expansion lever base portion 11. By this fixing operation, the expansion lever 10 and the weight 30 form a substantially U-shape that surrounds the laminated piezoelectric element 2.

  Thereafter, an adhesive (not shown) is injected from a screw hole 34 of the weight 30 into a required portion of the multilayer piezoelectric element 2 and a predetermined preload is applied by tightening the preload screw 50, followed by heat treatment or the like. Then, the injected adhesive (not shown) is cured, and the laminated piezoelectric element 2 is fixed.

  That is, the acoustic signal generator according to the present invention has two substantially U-shaped opposing surfaces formed by the magnifying lever base portion 11 and the support portion 31, that is, between the magnifying lever driving portion 12 and the receiving surface 33 of the weight 30. Further, the laminated piezoelectric element 2 having a displacement characteristic in the longitudinal direction is disposed, one end of which is in contact with the magnifying lever driving unit 12 and the other end is provided on the same surface as the receiving surface 33 of the weight 30. The end face of the preload screw 50 held in the screw hole 34 is in contact.

  The enlargement lever 10 includes an enlargement lever base portion 11, an enlargement lever driving portion 12, and an enlargement lever output portion 13, and is formed by pressing a metal plate material. The magnifying lever driving part 12 is supported by the magnifying lever base part 11, and an magnifying lever bending part 15 that is bent at 90 degrees by pressing is provided between the magnifying lever driving part 12 and the magnifying lever base part 11. ing. The expansion lever bending portion 15 functions as an elastic member that constantly applies a preload to the multilayer piezoelectric element 2, and is an important rotation center of the expansion lever driving portion 12 during operation of the multilayer piezoelectric element 2. Part.

  Ribs 14 are provided at both ends of the magnifying lever driving unit 12. The rib 14 not only improves the rigidity of the expansion lever driving unit 12 but also covers the periphery of the multilayer piezoelectric element 2 and protects it from mechanical impact. Two enlargement lever output portions 13 are formed at the upper end of each of the ribs 14, and the pad 60 is fixed on the four enlargement lever output portions 13 thus formed. The enlargement lever output portion 13 is formed at two locations formed on the upper surface of each of the ribs 14, but there is no significant difference in performance even if one location is provided.

  The pad 60 includes a protrusion 61 and a flange portion 62 that extends radially outward from the open end surface thereof. Since the protrusion 61 directly touches the user's face skin and transmits vibration, it is required to have low thermal conductivity, small specific gravity, relatively high rigidity, and good touch. In this set, for example, ABS resin or the like It is formed using. Moreover, since the front-end | tip of the projection part 61 contacts a user's head, it is preferable to protrude from the end surface of the flange part 62. FIG.

  The flange portion 62 has a function of generating air conduction sound. That is, the surface of the flange portion 62 is also displaced in synchronization with the displacement of the multilayer piezoelectric element 2 to displace air. This displacement is a displacement that is continuously generated by the laminated piezoelectric element 2 based on information from a connected mobile phone or the like, and its air propagation becomes an air conduction sound (general sound or sound). Therefore, it is preferable that the flange portion 62 of the pad 60 has a rigidity that can withstand displacement of air and has a mass as small as possible. 1 and 2, the flange portion 62 of this configuration is configured to have a dish-like shape with an opening at the tip, but does not necessarily require a dish shape having an opening above the tip. As shown, it may have a dish shape with an opening below (flange 63).

  In general, communication devices such as mobile phones place importance on echo performance from the viewpoint of communication quality, among basic characteristics such as volume, sound quality, and echo performance. For example, when extra vibration is generated from an air conduction speaker or a bone conduction speaker, the vibration is transmitted as an echo to the other party via a microphone, and communication quality deteriorates. In order to prevent excessive vibration, the mass ratio of the fixed portion and the movable portion of the acoustic signal generator, that is, the weight 30 having the enlarged lever base portion 11 and the support portion 31, the fixing screw 40 and the preload screw 50 is configured. The design of the mass ratio of the movable part constituted by the fixed part, the magnifying lever driving part 12, the magnifying lever output part 13 and the pad 60 is an important point for maintaining call quality. The mass ratio between the fixed part and the movable part is preferably such that the mass of the fixed part is higher than the mass of the movable part, but considering that the mounting space is limited, it is about 5: 1 or more and 7: 1 or less. It is practical.

  Next, the operation of the acoustic signal generator of the present invention will be described. The laminated piezoelectric element 2 is subjected to expansion and contraction corresponding to the applied signal in the longitudinal direction by applying an AC voltage corresponding to the acoustic signal from an external signal source via the input line.

  In accordance with the displacement of the laminated piezoelectric element 2, the enlargement lever driving unit 12 and the receiving surface 33 of the weight 30 are pushed. At this time, since the rigidity of the frame structure part formed by the receiving surface 33 and the support part 31 is much higher than the bending rigidity of the expansion lever bending part 15, the displacement of the laminated piezoelectric element 2 causes the expansion lever bending part 15 to bend. The magnifying lever driving unit 12 is displaced, and further, the displacement displaces the magnifying lever output unit 13 and the pad 60 formed thereon. This displacement corresponds to the expansion / compression of the laminated piezoelectric element 2.

  According to this structure using the lever structure with the enlarged lever bent portion 15 as the rotation center, the amount of displacement from the center portion of the pad 60 to the tip is 3 to 5 with respect to the amount of expansion and contraction of the laminated piezoelectric element 2. It is enlarged about twice. Therefore, the user can obtain sound information having a sufficient volume as a bone conduction sound by bringing the protrusion 61 of the pad 60 into contact with a predetermined position of the user's head.

  At the same time, the displacement reaching the pad 60 displaces the flange portion 62 of the pad 60 and gives displacement to the surrounding air. This displacement corresponds to the input signal of the laminated piezoelectric element 2, propagates in the air, and eventually the user transmits a signal from the connected device as sound. That is, the flange portion 62 functions as an air conduction speaker by repeating and propagating the air displacement corresponding to the input signal at the time of driving, and even if the user does not hit the projection 61 portion of the pad 60 on the head, You can listen to signals from external devices.

The disassembled perspective view of the acoustic signal generator by this invention. 1 is a cross-sectional view of an acoustic signal generator according to the present invention. The side view of other embodiment of the pad in the acoustic signal generator by this invention. Sectional drawing of the acoustic signal generator by a prior art.

Explanation of symbols

1 Enlargement lever 1a Enlargement lever base part 1b Enlargement lever output part
1c Enlarging lever elastic part 2 Multilayer piezoelectric element 2a Input line 3 Weight 4 Fixing screw 5 Preloading screw 6 Pad 10 Enlarging lever 11 Enlarging lever base 12 Enlarging lever driving part 13 Enlarging lever output part 14 Rib 15 Enlarging lever bending part 16 Hole 30 Weight 31 Supporting portion 32 Screw hole 33 Receiving surface 34 Screw hole 35 Hole
40 Fixing screw 50 Preloading screw 60 Pad 61 Protruding part 62 Flange part 63 Flange part

Claims (1)

  A laminate type piezoelectric element that mechanically vibrates due to expansion and contraction displacement according to an electric signal applied from the outside, a receiving surface that receives expansion and contraction displacement of the lamination type piezoelectric element, and a weight comprising a support portion that supports the lamination type piezoelectric element And an expansion lever that is mounted so as to cover the multilayer piezoelectric element and the support, and that expands and outputs mechanical vibration of the multilayer piezoelectric element, and a rigid pad at the output portion of the expansion lever The pad is composed of a protrusion having one end closed and a flange provided around the open end surface of the protrusion, and the edge of the flange is the tip of the protrusion. And an open end face.

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