Patent Application
20150245145
This application claims priority to and the benefit of Japanese Patent Application No. 2012-219799 filed on Oct. 1, 2012, the entire contents of which are incorporated herein by reference.
The present invention relates to a sound generator for vibrating a contact surface in contact with the sound generator and thereby causing the contact surface to generate a sound, a vibration member for the sound generator, and a sound generation system.
As a conventional vibration generator, there is one, for example, described in PLT 1 set forth below. The PLT 1 describes a vibration generator having a dynamic speaker structure including a case accommodating a magnet, a voice coil, and a diaphragm. Also, PLT 2 set forth below discloses a vibration generator including a weight made of an elastic body that is deformed in a bending manner or the like by vibration of a piezoelectric vibrator, thereby vibrating a vibrated member. Also, PLT 3 set forth below discloses a vibration generator including an elastic member that receives a load of a weight and is deformed in the bending manner or the like by vibration of the piezoelectric vibrator, thereby vibrating the vibrated member. Further, PLT 4 set forth below discloses a vibration generator including an elastic member that is deformed in the bending manner or the like by vibration of the piezoelectric vibrator, thereby vibrating the vibrated member.
PTL 1: Japanese Unexamined Utility Model (Registration) Application Publication No. 5-85192
PTL 2: Japanese Patent Application Laid-Open Publication No. 2007-74663
PTL 3: Japanese Patent Application Laid-Open Publication No. 2009-27413
PTL 4: Japanese Patent Application Laid-Open Publication No. 2009-27320
Since the vibration generator described in the PLT 1 having the dynamic speaker structure and various members including the case accommodating the magnet, the voice coil, and the diaphragm, a large number of components is inevitably used to constitute the vibration generator. Also, the vibration generators described in the PLT 2 to the PLT 4 use a piezoelectric element as the vibrator, and these vibration generators need to have a space therein in order to ensure the freedom of the deformation of the elastic body. Therefore, an increase in size of these vibration generators is unavoidable.
In view of the above problems, the present invention is to provide a sound generator a vibration member for the sound generator, and a sound generation system that may be easily configured.
In order to achieve the above, a sound generator according to the present invention includes:
a vibration unit having a piezoelectric element; and
a weight configured to apply a load to the vibration unit, wherein
the vibration unit deforms according to a sound signal while receiving the load from the weight, causing vibration of a contact surface in contact with the sound generator, wherein a sound is generated from the contact surface.
The piezoelectric element is a laminated piezoelectric element and deforms in a stretching and contracting manner along a lamination direction.
The vibration unit may have a cover member configured to vibrate the contact surface by transmitting the vibration caused by the deformation of the piezoelectric element to the contact surface.
The sound signal may be a signal having at least a portion of a frequency component higher than a predetermined threshold being cut or attenuated.
The sound signal may be a signal having an attenuation rate that, as the frequency becomes higher than the predetermined threshold, becomes higher gradually or in a stepwise manner.
The sound signal may be a signal having at least a portion of the frequency component higher than the predetermined threshold being cut or attenuated by a filter.
The contact surface may be a placing surface on which the sound generator is placed.
The sound signal is a sound signal of music or voice, and the music or the voice may be generated from the contact surface.
In order to achieve the above matter, also, a vibration member for a sound generator according to the present invention includes a piezoelectric element configured to deform according to a sound signal, causing vibration of a contact surface in contact with the vibration member for the sound generator, wherein a sound is generated from the contact surface.
In order to achieve the above matter, further, a sound generation system according to the present invention includes:
a sound generator having a vibration unit with a piezoelectric element and a weight configured to apply a load to the vibration unit; and
a contacted member having a contact surface configured to come into contact with the sound generator, wherein
the vibration unit deforms according to a sound signal while receiving the load from the weight, causing vibration of a contact surface of the contacted member, wherein a sound is generated from the contact surface.
According to the present invention, the sound generator that may be easily configured, the vibration member for the sound generator, and the sound system may be provided.
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
The panel 30 has a touch panel for detecting a contact, or a cover panel and the like for protecting the display unit 50, and is made of, for example, glass or synthetic resin such as acrylic and the like. The panel 30 has, for example, a rectangular shape. The panel 30 may be a flat plate or a curved panel with a smoothly inclined surface. The panel 30, in case of serving as the touch panel, detects a contact made by a user's finger, a pen, a stylus pen and the like. A detection method of the touch panel may be any one of an electrostatic capacitance method, a resistance film method, a surface acoustic wave method (or an ultrasound method), an infrared method, an electromagnetic induction method, a load detection method, and the like. According to the present embodiment, for convenience of explanation, the panel 30 is assumed as the touch panel.
The input unit 40 receives an operation input from a user and is constituted by using, for example, an operation button (an operation key). Note that the panel 30 also may receive the operation input from the user by detecting the contact made by the user.
The display unit 50 is a display device such as a liquid crystal display, an organic EL display, or an inorganic EL display.
The sound generator according to the present embodiment is provided with, on a side surface 20a that is one of longitudinal sides of the housing 20 of the mobile phone 10, a vibration unit 60 for the sound generator and an elastic member 70 that is a sheet-like member. The elastic member 70 is made of, for example, rubber, silicone, polyurethane, or the like. When the mobile phone 10 is placed with the side surface 20a facing down on a placing surface of a desk or the like, which is a horizontal surface, that is, when the mobile phone 10 is erected on its side, the mobile phone 10 is supported at two positions by the vibration unit 60 and the elastic member 70 on the placing surface. Arrangements of the vibration unit 60 and the elastic member 70 will be described in detail later.
The vibration unit 60 includes a piezoelectric element 61, an O-ring 62 used for a waterproof purpose, and a cap 63 having insulating property serving as a covering member. The piezoelectric element is an element that, upon application of an electric signal (a voltage) thereto, stretches/contracts or bends according to an electromechanical coupling coefficient of a constituent material. The piezoelectric element may be made of, for example, ceramic or crystal. The piezoelectric element may be a unimorph, a bimorph, or a laminated piezoelectric element. The laminated piezoelectric element is classified into a laminated bimorph element made up of laminated bimorphs (for example, 16 to 24 layers thereof) or a laminated piezoelectric element of a stack type having a multilayer structure made up of a plurality of dielectric layers made of, for example, PZT (lead zirconate titanate) and electrode layers disposed therebetween. The unimorph stretches/contracts upon application of the electrical signal thereto, while the bimorph bends upon application of the electrical signal thereto. The laminated piezoelectric element of the stack type stretches/contracts along a lamination direction upon application of the electrical signal thereto.
According to the present embodiment, the piezoelectric element 61 is the laminated piezoelectric element of the stack type. The laminated piezoelectric element 61, as illustrated in an enlarged cross-sectional view in
The laminated piezoelectric element 61 illustrated in
The laminated piezoelectric element 61 has a length of, for example, 5 mm to 120 mm in the lamination direction. A cross-sectional shape of the laminated piezoelectric element 61 in a direction intersecting the lamination direction may be, for example, a substantially square of 2 mm square to 10 mm square, or any shape other than square. The number of dielectrics 61a and the internal electrodes 61b constituting the laminated piezoelectric element 61 and a cross-sectional area of the laminated piezoelectric element 61 are appropriately determined based on weight of the mobile phone 10 serving as the weight (for example, 80 g to 800 g when the mobile phone 10 is a mobile electronic apparatus), in such a manner as to sufficiently secure a sound pressure or sound quality of a sound generated from the contact surface of the desk or the like in contact with the vibration unit 60.
To the laminated piezoelectric element 61, as illustrated in
The laminated piezoelectric element 61 as described above is used for, for example, fuel injection control of a vehicle. The present inventor has conceived that the laminated piezoelectric element 61 as described above is sufficiently effective as a vibration element for generating a sound from the contact surface of the desk or the like in contact with the sound generator.
Note that, in
The laminated piezoelectric element 61, as illustrated by a partially enlarged cross-sectional view in
The cap 63 is made of a material such as hard plastic or the like that can reliably transmit stretching/contracting vibration of the laminated piezoelectric element 61 to the placing surface (the contact surface) of the desk and the like. When it is preferred to suppress damaging the placing surface, the cap 63 may be made of relatively soft plastic instead of the hard plastic. The cap 63 includes an entry portion 63a and a protrusion portion 63b formed thereon, such that, with the cap 63 being attached to the laminated piezoelectric element 61, the entry portion 63a is positioned inside the slit 101, and the protrusion portion 63b protrudes from the housing 20. An O-ring 62 is disposed, for the waterproof purpose, on an outer periphery of the entrance portion 63a inside the slit 101. The O-ring 62 is made of, for example, silicone. The O-ring 62 prevents the water and dusts from entering the slit 101. Also, the protruding portion 63b has a distal end in a hemispherical shape. Note that the shape of the distal end of the protrusion portion 63b is not limited to the hemispherical shape but may be any shape as long as being capable of ensuring point contact or surface contact with the placing surface (the contact surface) of the desk and the like and transmitting the stretching/contracting vibration of the laminated piezoelectric element 61. In
The radio communication unit 110 has a known configuration and wirelessly connected to a communication network via a base station. The controller 130 is a processor for controlling overall operations of the mobile phone 10. The controller 130 applies the reproduction audio signal (a voltage corresponding to the reproduction audio signal of voice of the other party or music including ringtone and songs) to the laminated piezoelectric element 61 via the piezoelectric element drive unit 120. The reproduction audio signal may be based on music data stored in an internal memory, or music data stored in an external server or the like to be reproduced via the network.
The piezoelectric element drive unit 120, as illustrated in
The boosting circuit 122 boosts a voltage of the analogue reproduction audio signal being input and, via the LPF 123, applies the analogue reproduction audio signal to the laminated piezoelectric element 61. Here, a maximum voltage of the reproduction audio signal applied to the laminated piezoelectric element 61 by the boosting circuit 122 may be, for example, 10 Vpp to 50 Vpp. However, the maximum voltage is not limited thereto but may be appropriately adjusted based on the weight of the mobile phone 10 or performance of the laminated piezoelectric element 61. Note that a DC voltage of the reproduction audio signal applied to the laminated piezoelectric element 61 may be biased, and the maximum voltage may be set around such a bias voltage.
Also, as the frequency becomes higher, not only the laminated piezoelectric element 61 but the piezoelectric elements, in general, have more power loss. Therefore, the LPF 123 is set to have frequency characteristics to attenuate or cut at least a portion of frequency components at approximately 10 kHz to 50 kHz or higher, or frequency characteristics to increase an attenuation rate gradually or in stages.
Next, with reference to
In
The vibration unit 60 includes a lowermost end portion 601. The lowermost end portion 601 is a portion of the vibration unit 60 that contacts with the placing surface 150 when the mobile phone 10 is placed with the side surface 20a facing down on the placing surface 150 of the desk or the like. The lowermost end portion 601 is, for example, a distal end portion of the cap 63.
The mobile phone 10 includes a lowermost end portion 101. The lowermost end portion 101 is a portion of the mobile phone 10 that contacts with the placing surface 150 when the mobile phone 10 is placed with the side surface 20a facing down on the placing surface 150 of the desk or the like, assuming that the vibration unit 60 is omitted. The lowermost end portion 101 of the mobile phone 10 is, for example, a corner of the housing 20 but not limited thereto. When a protrusion portion protruding from the side surface 20a is provided thereto, the protrusion portion may serve as the lowermost end portion 101 of the mobile phone 10. The protrusion portion may be, for example, a side key, a connector cap, or the like.
In
In
Preferably, the vibration unit 60, on the side surface 20a in the region R2, is disposed as close to the dotted line L as possible. Thereby, the load applied to the vibration unit 60 becomes larger than that when the vibration unit 60 is disposed at a position remote from the dotted line L on the side surface 20a in the region R2, allowing effective use of the mobile phone 10 serving as the weight of the sound generator.
Preferably, the elastic member 70, on the side surface 20a in the region R1, is disposed as far from the dotted line L as possible. Thereby, when the vibration unit 60 is disposed as close to the dotted line L as possible, a sufficient distance is ensured between the elastic member 70 and the vibrating portion 60, allowing stable placement of the sound generator on the placing surface 150.
The lowermost end portion 601 of the vibration unit 60 preferably locates on the side of the placing surface 150 with respect to the dotted line I when the laminated piezoelectric element 61 stretches maximum from the non-stretching state thereof with no voltage applied thereto, or when amplitude of the laminated piezoelectric element 61 becomes maximum. That is, the lowermost end portion 601 preferably protrudes from the dotted line I toward the placing surface 150 when the laminated piezoelectric element 61 stretches maximum from the non-stretching state thereof with no voltage applied thereto, or when the amplitude the laminated piezoelectric element 61 becomes maximum. Thereby, the vibration unit 60 may appropriately vibrate the placing surface 150.
Further, the lowermost end portion 601 of the vibration unit 60 preferably locates on the side of the placing surface 150 with respect to the dotted line I when the laminated piezoelectric element 61 contracts maximum from the non-stretching state thereof with no voltage applied thereto, or when the amplitude of the laminated piezoelectric element 61 becomes minimum. That is, the lowermost end portion 601 preferably protrudes from the dotted line I toward the placing surface 150 when the laminated piezoelectric element 61 contracts maximum from the non-stretching state thereof with no voltage applied thereto, or when the amplitude of the laminated piezoelectric element 61 becomes minimum. Thereby, the lowermost end portion 101 of the mobile phone 10 is unlikely to contact the placing surface 150 and, for example, some coating of the housing 20 is unlikely to come off. Further, an abnormal noise is unlikely to be generated between the lowermost end portion 101 and the placing surface 150.
Note that, for example, a commercially available stand or the like may be attached to the housing 20, and the mobile phone 10 may be erected with the side surface 20a facing down on the placing surface of the desk or the like. In this case, the mobile phone 10 is supported at the two positions by the vibration unit 60 and the elastic member 70 on the side surface 20a, and further supported by the stand.
In this state, when the laminated piezoelectric element 61 of the vibration unit 60 is driven by the reproduction audio signal, the laminated piezoelectric element 61, as illustrated in
Here, as described above, when the laminated piezoelectric element 61 stretches maximum, the distal end portion of the cap 63 preferably locates on the side of the placing surface 150 with respect to the line (the dashed line I in
Preferably, the distance d between the side surface 20a and an opposing surface 63c of the cap 63 illustrated in
The position of the vibration unit 60 on the side surface 20a, the length of the laminated piezoelectric element 61 in the lamination direction, and a size of the cap 63 may be appropriately determined so as to satisfy conditions described above.
Using the piezoelectric element as a vibration source, the sound generator of the present embodiment, as compared with relevant vibration generating apparatuses having a dynamic speaker structure, may reduce the number of components thereof, allowing easy configuration. Also, the laminated piezoelectric element 61 of the stack type is used as the piezoelectric element and performs the stretching/contracting vibration in the lamination direction based on the reproduction audio signal, and the stretching/contracting vibration of the laminated piezoelectric element 61 is transmitted to the placing surface (the contact surface) 150. Therefore, the vibration may be efficiently transmitted in a contract direction (deformation direction) to the placing surface (the contact surface) 150, thereby efficiently vibrating the placing surface (the contact surface) 150. Moreover, since the laminated piezoelectric element 61 comes into contact with the placing surface (the contact surface) 150 via the cap 63, the laminated piezoelectric element 61 may be prevented from being damaged. Further, when the mobile phone is erected on its side with the cap 63 of the vibration unit 60 contacting with the placing surface (the contact surface) 150, the weight of the mobile phone 10 is applied as the load to the cap 63. Therefore, the cap 63 may reliably come into contact with the placing surface (the contact surface) 150, efficiently transmitting the stretching/contracting vibration of the vibration unit 60 to the placing surface (the contact surface) 150.
Further, the sound generator of the present embodiment may directly transmit more vibration of the laminated piezoelectric element to the contact surface (the placing surface). Therefore, unlike relevant techniques for transmitting the vibration of the laminated piezoelectric element to another elastic body, at the time of sound generation there is no need to depend on a limit frequency on a high frequency side at which the another elastic body may vibrate. Note that the limit frequency on the high frequency side at which the another elastic body may vibrate takes an inverse of a shortest time from when the another elastic body is deformed by the piezoelectric element to when the another elastic body is restored to be deformable again. In view of this, the weight of the sound generator according to the present embodiment preferably has sufficient rigidity (bending strength) not to be deformed in a bending manner by the deformation of the piezoelectric element.
As illustrated in
Next, with reference to
In
In
The vibration unit 60 is disposed on the dotted line L on the side surface 20a. That is, the vibration unit 60 is disposed so as to locate on the line that is perpendicular to the placing surface 150 and passes through the center of gravity G of the mobile phone 10 when the mobile phone 10 is placed with the side surface 20a facing down on the placing surface 150 such as a desk and the like. Thereby, the weight of the mobile phone 10 may be applied as the load to the vibration unit 60, and the stretching/contracting vibration of the vibration unit 60 may be efficiently transmitted to the placing surface (the contact surface) 150. Note that, when D1=D2 is satisfied, that is, when the elastic member 70 and the elastic member 71 are disposed symmetrically in the horizontal direction across the vibration unit 60, the sound generator may be stably placed on the placing surface 150.
When the laminated piezoelectric element 61 is driven based on the reproduced audio signal, the vibration unit 60 performs the stretching/contracting vibration based on the reproduced audio signal while the cap 63 remains in contact with the placing surface (the contact surface) 150. Note that, when there is no inconvenience such as the generation of the abnormal noise caused by lower end portions of the elastic member 70 and the elastic member 71 coming into contact with the placing surface 150, the cap 63 may be slightly spaced apart from the placing surface 150.
When the mobile phone 10 is placed with the side surface 20a facing down on the placing surface 150 of the desk or the like, the elastic member 70 and the elastic member 71 receive the weight of the mobile phone 10 applied as the load and thus elastically deform. That is, the elastic member 70 and the elastic member 71 contract in a direction perpendicular to the placing surface 150 upon application of the weight of the mobile phone 10 thereto. Preferably, elastic deformation amounts of the elastic member 70 and the elastic member 71 when the laminated piezoelectric element 61 does not stretch with no voltage applied thereto is larger than a deformation amount of the laminated piezoelectric element 61 from when the laminated piezoelectric element 61 does not stretch with no voltage applied thereto to when the laminated piezoelectric element 61 stretches maximum. Thereby, when the laminated piezoelectric element 61 stretches maximum, the elastic member 70 and the elastic member 71 are unlikely to separate from the placing surface 150, allowing the stable placement of the sound generator on the placing surface 150.
Note that the present invention is not limited to the above embodiments but may be modified or changed in various manners. With reference to
The support 100 illustrated in
The support 100 illustrated in
Further, in the above embodiment and variations illustrated in
In
Although in the above embodiments the vibration unit 60 is disposed on the side surface 20a of the housing 20 and protrudes therefrom, the present invention is not limited thereto. Depending on sizes of the housing 20 and the vibration unit 60, the vibration unit 60 may protrude from the battery lid 21, for example.
Also, although in the above embodiments the desk serves as the contacted member and the placing surface of the desk, which is the horizontal surface, serves as the contact surface, the present invention is not limited thereto. The contact surface does not need to be the horizontal surface but may be, for example, a surface of the desk perpendicular to the ground. The contacted member having the surface perpendicular to the ground may be, for example, a partition for separating a space.
Further, although in the above embodiments the sound generator is mounted on the mobile phone 10 serving as the weight, the weight is not limited thereto. For example, various electronic devices such as a portable music player, a stationary TV set, a telephone conference system, a laptop computer, a projector, a wall-mounted clock/TV set, an alarm clock, a photo frame, and the like may serve as the weight, and the sound generator may be mounted thereon. Also, the weight is not limited to the electronic device but may be, for example, a vase, a chair, and the like. Further, the present invention is applicable not only as the sound generator but also as a vibration member for the sound generator having the piezoelectric element, or as a sound generation system that includes the sound generator and the contacted member having the contact surface to come into contact with the sound generator. Note that such variations may be included in the scope of the present invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2012-219799 | Oct 2012 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2013/005808 | 9/30/2013 | WO | 00 |
