Panel-type speaker

Abstract

A panel-type speaker includes a panel and an actuator and is configured to vibrate the panel by the actuator so as to output sound waves from the panel, the actuator includes: a vibrating plate; and a piezoelectric element arranged on at least one surface of the vibrating plate, the piezoelectric element has, at a central portion of the piezoelectric element in a plan view, an opening from which the vibrating plate is exposed, and at a portion of the vibrating plate exposed from the opening, the vibrating plate is coupled to the panel.

What is claimed is: 
     
         1 . A panel-type speaker which comprises a panel and an actuator and is configured to vibrate the panel by the actuator so as to output sound waves from the panel, the actuator comprising:
 a vibrating plate; and   a piezoelectric element arranged on at least one surface of the vibrating plate, wherein the piezoelectric element has, at a central portion of the piezoelectric element in a plan view, an opening from which the vibrating plate is exposed, and   at a portion of the vibrating plate exposed from the opening, the vibrating plate is coupled to the panel.   
     
     
         2 . The panel-type speaker according to  claim 1 , wherein the actuator further comprises:
 a through-hole which is provided at the portion of the vibrating plate exposed from the opening and extends from one surface to other surface of the vibrating plate; and   a screw passing through the through-hole,   wherein the opening is provided to surround the through-hole, and   the vibrating plate is coupled to the panel by the screw.   
     
     
         3 . The panel-type speaker according to  claim 1 , wherein the actuator further comprises:
 a plurality of through-holes which is provided at the portion of the vibrating plate exposed from the opening and extends from one surface to other surface of the vibrating plate; and   a plurality of screws each passing through a respective one of the plurality of through-holes,   wherein the opening is provided to surround the plurality of through-holes,   the vibrating plate is coupled to the panel by the plurality of screws, and   the plurality of through-holes is provided in a direction along a propagation direction of a bending vibration of the vibrating plate.   
     
     
         4 . A panel-type speaker which comprises a panel and an actuator and is configured to vibrate the panel by the actuator so as to output sound waves from the panel, the speaker comprising:
 a vibration transmission unit which has one end connected to the panel and other end connected to the actuator and is configured to transmit a vibration of the actuator to the panel; and   a restraint unit configured to restrain the actuator to the vibration transmission unit,   wherein the actuator comprises   a vibrating plate; and   a piezoelectric element arranged on at least one surface of the vibrating plate,   wherein a length of a portion of the restraint unit along a specific direction is set to a predetermined length so that a resonance frequency of a bending vibration propagating in the specific direction in a plane of the vibrating plate becomes a predetermined frequency.   
     
     
         5 . The panel-type speaker according to  claim 4 , wherein the vibrating plate is rectangular in a plan view, and the specific direction is a direction along a longitudinal direction of the vibrating plate in a plan view. 
     
     
         6 . The panel-type speaker according to  claim 5 , wherein the length of the portion of the restraint unit along the specific direction is set to a predetermined length so that the resonance frequency of the bending vibration propagating in the specific direction approaches a frequency of a bending vibration propagating in a direction orthogonal to the specific direction. 
     
     
         7 . The panel-type speaker according to  claim 6 , wherein the restraint unit comprises a fastening member for fastening to the vibration transmission unit,
 wherein the vibrating plate is restrained to the vibration transmission unit by the fastening members provided in at least two locations in the specific direction, and a length of a restrained portion is defined by a gap between the fastening members in the specific direction.   
     
     
         8 . The panel-type speaker according to  claim 4 , wherein the restraint unit comprises a fastening member for fastening to the vibration transmission unit and a flat plate-shaped spacer,
 wherein the spacer is brought into contact with a surface opposite to a surface of the vibrating plate connected to the vibration transmission unit, and the fastening member is fastened to the vibration transmission unit via the spacer,   wherein a length of a restrained portion is defined by a length of the spacer in the specific direction.   
     
     
         9 . The panel-type speaker according to  claim 5 , wherein the restraint unit comprises a fastening member for fastening to the vibration transmission unit and a flat plate-shaped spacer,
 wherein the spacer is brought into contact with a surface opposite to a surface of the vibrating plate connected to the vibration transmission unit, and the fastening member is fastened to the vibration transmission unit via the spacer,   wherein a length of a restrained portion is defined by a length of the spacer in the specific direction.   
     
     
         10 . The panel-type speaker according to  claim 6 , wherein the restraint unit comprises a fastening member for fastening to the vibration transmission unit and a flat plate-shaped spacer,
 wherein the spacer is brought into contact with a surface opposite to a surface of the vibrating plate connected to the vibration transmission unit, and the fastening member is fastened to the vibration transmission unit via the spacer,   wherein a length of a restrained portion is defined by a length of the spacer in the specific direction.   
     
     
         11 . The panel-type speaker according to  claim 4 , wherein when, in a plan view, the specific direction is defined as a first direction and a direction orthogonal to the first direction is defined as a second direction, a length of a restrained portion in the second direction by the restraint unit is set to a second length so that a resonance frequency of a bending vibration propagating in a plane of the vibrating plate in the second direction becomes a predetermined frequency. 
     
     
         12 . The panel-type speaker according to  claim 5 , wherein when, in a plan view, the specific direction is defined as a first direction and a direction orthogonal to the first direction is defined as a second direction, a length of a restrained portion in the second direction by the restraint unit is set to a second length so that a resonance frequency of a bending vibration propagating in a plane of the vibrating plate in the second direction becomes a predetermined frequency. 
     
     
         13 . The panel-type speaker according to  claim 6 , wherein when, in a plan view, the specific direction is defined as a first direction and a direction orthogonal to the first direction is defined as a second direction, a length of a restrained portion in the second direction by the restraint unit is set to a second length so that a resonance frequency of a bending vibration propagating in a plane of the vibrating plate in the second direction becomes a predetermined frequency. 
     
     
         14 . The panel-type speaker according to  claim 7 , wherein when, in a plan view, the specific direction is defined as a first direction and a direction orthogonal to the first direction is defined as a second direction, a length of a restrained portion in the second direction by the restraint unit is set to a second length so that a resonance frequency of a bending vibration propagating in a plane of the vibrating plate in the second direction becomes a predetermined frequency. 
     
     
         15 . The panel-type speaker according to  claim 8 , wherein when, in a plan view, the specific direction is defined as a first direction and a direction orthogonal to the first direction is defined as a second direction, a length of a restrained portion in the second direction by the restraint unit is set to a second length so that a resonance frequency of a bending vibration propagating in a plane of the vibrating plate in the second direction becomes a predetermined frequency. 
     
     
         16 . The panel-type speaker according to  claim 7 , wherein the vibration transmission unit comprises fastened members in at least two locations in the first direction and in at least two locations in the second direction, to which the fastening members are fastened, and a restraint direction can be selected by selectively fastening the fastening members to the fastened members in the first direction or the fastened members in the second direction. 
     
     
         17 . The panel-type speaker according to  claim 4 , wherein the vibration transmission unit comprises fastened members at three or more locations in the specific direction, to which the fastening members are fastened, and a length of a restrained portion is set by a gap between the fastening members fastened to two of the fastened members. 
     
     
         18 . The panel-type speaker according to  claim 5 , wherein the vibration transmission unit comprises fastened members at three or more locations in the specific direction, to which the fastening members are fastened, and a length of a restrained portion is set by a gap between the fastening members fastened to two of the fastened members. 
     
     
         19 . The panel-type speaker according to  claim 6 , wherein the vibration transmission unit comprises fastened members at three or more locations in the specific direction, to which the fastening members are fastened, and a length of a restrained portion is set by a gap between the fastening members fastened to two of the fastened members. 
     
     
         20 . The panel-type speaker according to  claim 7 , wherein the vibration transmission unit comprises fastened members at three or more locations in the specific direction, to which the fastening members are fastened, and a length of a restrained portion is set by a gap between the fastening members fastened to two of the fastened members.