Abstract:
A loudspeaker includes an electro-acoustic transducer for converting electrical audio signals into sound waves, and a housing that supports the electro-acoustic transducer. The loudspeaker also includes a shutter that is supported by the housing and is displaceable between a first, closed position in which the shutter substantially covers the transducer, and a second, open position in which the transducer is exposed.

Description:
BACKGROUND 
     This disclosure relates to shuttered loudspeakers. 
     It is known to provide loudspeakers with movable parts. An example of this is the use of so called “pop-up” speakers in automotive vehicles. Such pop-up speakers are known to rise out of an interior surface of the vehicle when active, and retract back into the vehicle surface when inactive. 
     While the use of such loudspeakers may provide an intriguing visual effect, the fact that the loudspeakers are movable may not necessarily benefit the acoustic aspects of the loudspeaker. Furthermore, since these pop-up speakers often extend outwardly from an interior surface of a vehicle, they may reduce visibility when in the active, extended state. 
     SUMMARY 
     In one aspect, a loudspeaker includes an electro-acoustic transducer for converting electrical audio signals into sound waves, and a housing that supports the electro-acoustic transducer. The loudspeaker also includes a shutter that is supported by the housing and is displaceable between a first, closed position in which the shutter substantially covers the transducer, and a second, open position in which the transducer is exposed. 
     Implementations may include one of the following features, or any combination thereof. 
     In some implementations, the loudspeaker does not include a grille for protecting the transducer. 
     In certain implementations, the shutter includes at least one moveable blade. 
     In some examples, the shutter includes at least one rotatable blade. 
     In certain examples, the loudspeaker also includes an electric motor, and displacement of the shutter is driven by the electric motor. 
     In some cases, the loudspeaker also includes control electronics coupled to the electric motor. The control electronics are configured to receive a signal indicative of a power state of an associated audio system, and drive the electric motor in response to the signal. 
     In some implementations, the control electronics include a processor coupled to the electric motor, and instructions stored on a non-transitory computer-readable media. The instructions, when executed, cause the processor to receive a signal indicative of a power state of an associated audio system; and drive the electric motor in response to signal. The instructions, when executed, may cause the processor to drive the electric motor to open the shutter to expose the electro-acoustic transducer when the processor receives a signal indicating that the associated audio system has been powered on. Alternatively or additionally, the instructions, when executed, cause the processor to drive the electric motor to close the shutter when the processor receives a signal indicating that the associated audio system has been powered off. 
     In certain implementations, the loudspeaker also includes a proximity detector for detecting the presence of an object in proximity the electro-acoustic transducer. The loudspeaker is configured to displace the shutter to the first, closed position in response to detecting the presence of an object in proximity to the electro-acoustic transducer. 
     In some examples the loudspeaker also includes a proximity sensor for detecting the presence of an object in proximity to the electro-acoustic transducer, an electric motor for driving displacement of the shutter, and control electronics that are coupled to the proximity sensor and to the electric motor. The control electronics are configured to drive the electric motor to close the shutter when the control electronics receive a signal from the proximity sensor indicating that an object is in proximity to the electro-acoustic transducer. 
     In certain examples, the control electronics include a processor that is coupled to the proximity sensor and to the electric motor, and instructions stored on a non-transitory computer-readable media. The instructions, when executed, cause the processor to drive the electric motor to close the shutter when the processor receives a signal from the proximity sensor indicating that an object is in proximity to the electro-acoustic transducer. The instructions, when executed, may also cause the processor to automatically shut the electro-acoustic transducer off, such that no audio is rendered via the electro-acoustic transducer, until the shutter opens up again. 
     In some cases, the shutter comprises a mechanical iris comprising a plurality of overlapping blades which are displaceable to open and close an aperture formed by the blades. 
     In certain cases, wherein the loudspeaker is configured such that the shutter automatically opens when an associated audio system is powered on and automatically closes when the associated audio system is powered off. 
     In some implementations, the shutter is further displaceable between the second, open position and a third, open position, and the loudspeaker is configured such that the shutter moves between the second, open position and the third, open position in response to changes in audio volume. 
     In certain implementations, the loudspeaker is configured such that an aperture defined by the shutter increases in response to an increase in audio volume. 
     In another aspect, a vehicle audio system includes a plurality of loudspeakers, a head unit, and an audio amplifier for amplifying and filtering entertainment audio received from the head unit for distribution to a plurality of speakers positioned about the vehicle cabin. At least one of the plurality of loudspeakers is a shuttered loudspeaker that includes an electro-acoustic transducer for converting electrical audio signals into sound waves, a housing that supports the electro-acoustic transducer, and a shutter that is supported by the housing and is displaceable between a first, closed position in which the shutter substantially covers the transducer, and a second, open position in which the transducer is exposed. 
     Implementations may include one of the above and/or below features, or any combination thereof. 
     In some implementations, the shuttered loudspeaker is disposed on an A-pillar in a vehicle cabin. 
     In certain implementations, the shuttered loudspeaker also includes an electric motor for driving displacement of the shutter, and a control electronics coupled to the electric motor. The control electronics are configured to drive the electric motor to control displacement of the shutter in response to signals received from the audio amplifier. 
     In some examples, the control electronics includes a processor coupled to the electric motor, and instructions stored on a non-transitory computer-readable media. The instructions, when executed, cause the processor to drive the electric motor to control displacement of the shutter in response to signals received from the audio amplifier. 
     In certain examples, the shuttered loudspeaker also includes a proximity sensor for detecting the presence of an object near the electro-acoustic transducer, an electric motor for driving displacement of the shutter, and control electronics coupled to the proximity sensor and to the electric motor. The control electronics are configured to drive the electric motor to close the shutter when the control electronics receives a signal from the proximity sensor indicating that an object is near the electro-acoustic transducer. 
     In some cases, the control electronics include a processor coupled to the proximity sensor and to the electric motor, and instructions stored on a non-transitory computer-readable media The instructions, when executed, cause the processor to drive the electric motor to close the shutter when the processor receives a signal from the proximity sensor indicating that an object is near the electro-acoustic transducer. The instructions, when executed, may also cause the processor to automatically shut the electro-acoustic transducer off, such that no audio is rendered via the electro-acoustic transducer, until the shutter opens up again. 
     In certain cases, the shutter includes a mechanical iris that includes a plurality of overlapping blades which are displaceable to open and close an aperture formed by the blades. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are front elevation views of a shuttered loudspeaker including a mechanical iris in a closed and an open position, respectively. 
         FIG. 2  illustrates the mechanical iris, and associated control electronics, from the shuttered loudspeaker of  FIG. 1A . 
         FIG. 3A  is a front elevation view of a shuttered loudspeaker having a proximity detector. 
         FIG. 3B  illustrates a mechanical iris, and associated circuitry, from the shuttered loudspeaker of  FIG. 3A . 
         FIG. 4  illustrates the shuttered loudspeaker of  FIG. 3A  installed on an A-pillar in a vehicle&#39;s passenger cabin. 
         FIG. 5  is a schematic representation of a vehicle audio system including the shuttered loudspeakers of  FIG. 3A . 
         FIGS. 6A and 6B  illustrate an alternative shutter configuration in a closed and open position, respectively. 
         FIG. 7  illustrates a home entertainment system which includes shuttered loudspeakers. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1A and 1B , a shuttered loudspeaker  100  includes an electro-acoustic transducer  102  which is mounted in a housing  104 . A shutter  106  is mounted to the housing  104  coincident with the electro-acoustic transducer  102 . The shutter  106  is displaceable between a first position ( FIG. 1A ) in which the shutter  106  is closed and substantially covers the electro-acoustic transducer  102  (i.e., in the closed state the shutter covers at least 90%, e.g., 95%-100%, of the radiating surface of the electroacoustic transducer), and a second position ( FIG. 1B ) in which the shutter  106  is open to expose the electro-acoustic transducer  102  in the housing  104 . 
     The shuttered loudspeaker  100  is configured such that the shutter  106  opens automatically when the shuttered loudspeaker  100 , or an associated audio system, is powered on and closes automatically when the shuttered loudspeaker  100 , or the associated audio system, is powered off. This provides a protective cover for the electro-acoustic transducer  102 , which can help to inhibit damage to the electro-acoustic transducer, while the shuttered loudspeaker  100  is powered off. The protection offered by the shutter  106  can allow the loudspeaker  100  to operate without the need for a grille to protect the electro-acoustic transducer  102 . This can allow the shuttered loudspeaker  100  to operate with 100% acoustic transparency by completely exposing a front radiating surface of the electro-acoustic transducer  102 . This can provide a benefit over conventional loudspeakers with grille covered transducers, which may only achieve 30% to 40% acoustic transparency. 
     In one example, the shutter  106  is in the form of a mechanical iris. As illustrated in  FIG. 2 , an exemplary mechanical iris  200  includes a base ring  202 , a blade actuating ring  204 , and a plurality of blades  206 . Each iris blade  206  is pivotally attached to the base ring  202  by a pivot pin  208 . Each of the blades  206  also includes a slider pin  210  which is received in a corresponding slot  212  in the blade actuating ring  204 . The base ring  202  is fixedly attached to the housing  104  ( FIG. 1 ) and the blade actuating ring  204  is rotatable relative to the base ring  202 . 
     The mechanical iris  202  is opened or closed by rotating the blade actuating ring  204  around the center while the base ring  202  is held stationary via its connection to the housing  104  ( FIG. 1 ). The rotation of the blade actuating ring  204  relative to the base ring  202  causes the slider pins  210  to slide within the slots  212  in the blade actuator ring  204 , which, in turn, causes the blades  206  to pivot about their respective pivot pins  208 . 
     Motion of the blades  206  can be driven by an electric motor  214 . In the illustrates example, the electric motor  214  drives a gear  216 , which, in turn, engages a set of gear teeth  218  along the outer peripheral edge of the blade actuating ring  204  to drive motion of the blade actuating ring  204 . 
     Control electronics  219  including a processor  220  and associated memory  222  (e.g., non-volatile memory, e.g., ROM) are provided for controlling operation of the electric motor  214 . Instructions stored on the memory, when executed by the processor  220 , cause the processor to: receive a signal (e.g., from an associated audio amplifier or tuner/receiver) indicative of a power state of an associated audio system, and to drive the electric motor  214  in response to signal. For example, the instructions will cause the processor  220  to drive the electric motor  214  to open the shutter  106  to expose the electro-acoustic transducer  102  ( FIG. 1B ) when the processor  220  receives a signal indicating that the associated audio system has been powered on. And, the instructions will cause the processor  220  to drive the electric motor  214  to close the shutter  106  when the processor  220  receives a signal indicating that the associated audio system has been powered off. In some cases, the control electronics  219  may be housed within another component (e.g., an audio amplifier, or receiver) of an associated audio system. 
     With reference to  FIGS. 3A and 3B , further protection can be provided by incorporating a proximity sensor  300  into the loudspeaker  100 . The proximity sensor  300  can be used to allow the shuttered loudspeaker  100  to detect an object, such as a person&#39;s hand, approaching the exposed surface of the electro-acoustic transducer  102 . The proximity sensor  300  may include one or more IR detectors mounted on the housing  104 . 
     The shuttered loudspeaker  100  can be configured such that, in response to detecting something approaching the electro-acoustic transducer  102 , the shutter  106  closes to protect the transducer  102 . For example, the instructions stored on the memory  222  ( FIG. 3B ) may cause the processor  220  to drive the electric motor  214  to close the shutter  106  when the processor  220  receives a signal from the proximity sensor  300  indicating that an object is near or approaching the electro-acoustic transducer  102 . This can help to prevent an approaching object from contacting, and potentially damaging, the electro-acoustic transducer  102 . This may be particularly beneficial for automotive applications, where the shutter  106  can be used to protect the electro-acoustic transducer  102  from flying debris in the event of an abrupt acceleration or a crash. 
     In some cases, the instructions may also cause the processor  220  to automatically shut the electro-acoustic transducer  102  off until the shutter  106  opens up again (e.g., when the object/threat is no longer present). This can be used to help provide an audible feedback to indicate that a problem has been detected. For example, the control electronics  219  may control a switch to power the electro-acoustic transducer  102  on and off. Alternatively or additionally, the control electronics  219  may be configured to communicate the detection of an object, and/or the closing of the shutter  106 , to another audio system component, such an audio amplifier or receiver, to control operation of the electro-acoustic transducer  102 . 
       FIG. 4  illustrates the shuttered loudspeaker  100  employed in a vehicle as part of the vehicle&#39;s audio system. Specifically, in the implementation illustrated in  FIG. 4 , the shuttered loudspeaker  100  is utilized as a tweeter positioned on an A-pillar  400  in a passenger compartment  402  of a vehicle. As used herein, “A-pillars” are the structural members (columns) of a vehicle that are along the left and right sides of the front windshield. This configuration provides a benefit over tradition pop-up speakers, which could pose a visual obstruction if integrated on a vehicle&#39;s A-pillar  400 , while still providing a visual impression of motion associated with the shuttered loudspeaker  100 . However, in the illustrated configuration, the tweeters are small enough to be incorporated into the A-pillar  400 , and, since the tweeters do not rise out of the interior surface of the vehicle, they do not present a visual obstruction when in use. 
     An example of such a vehicle audio system  500  is illustrated in  FIG. 5 . The system  500  includes a head unit  502  which is typically positioned in the dash board  503  of a vehicle. The head unit  502  provides entertainment audio to an audio amplifier  504 , which, in some cases, may be positioned underneath one of the vehicle&#39;s seats. The audio amplifier  504  amplifies and filters the entertainment audio for distribution to a plurality of speakers positioned about the vehicle cabin  402 . In some cases, the functions of the amplifier and the head unit may be packaged in a common housing. 
     In this example, the plurality of speakers includes a subwoofer  506  for reproducing low frequency sounds in the range of about 20 Hz to about 200 Hz. The subwoofer  506  is positioned behind the vehicle&#39;s rear seats (e.g., in a package shelf of the passenger cabin). Woofers  508  for reproducing sounds in the 40 Hz to 1 kHz range, and mid-range speakers  510 , for reproducing sounds in the 300 Hz to 5 kHz frequency range, are arranged in the front and rear doors, and a pair of tweeters implemented in the form of shuttered loudspeakers  100 , as described above, positioned in the vehicle&#39;s A-pillars  400 . Wiring connects the head unit  502  to the amplifier  504  and the amplifier to the plurality of speakers. Additional wires may be provided between the amplifier  504  and the shuttered loudspeakers  100  in order to control the movement of the shutters  106  ( FIG. 1A ). 
     The shuttered loudspeakers  100  can be configured such that their respective shutters  106  ( FIG. 1A ) open in response to a signal from the amplifier  504  indicating that the audio system  500  has been powered on. Likewise, the shuttered loudspeakers  100  can be configured such that their respective shutters  106  ( FIG. 1A ) close in response to a signal from the amplifier  504  indicating that the audio system  500  has been powered off. 
     Additionally, the shuttered loudspeakers  100  may also be configured with proximity detection, such as described above with respect to  FIGS. 3A and 3B , such that the shutter  106  ( FIG. 1A ) closes if an object is detected in proximity the associated one of the shuttered loudspeakers  100 . The shutter  106  ( FIG. 1A ) may remain closed until the object is no longer detected. In such cases, the audio system  500  may be configured to shut down audio from the associated shuttered loudspeaker  100  until the shutter  106  opens up again. 
     In some cases, in response to the detection of an object in close proximity to one of the shuttered loudspeakers  100 , the audio system  500  may be configured to shut down all high frequency audio, and, in some examples, even shut down the midrange audio, until the shutter  106  opens up again. This shutting down of audio can help to provide the user with audible feedback to indicate that the loudspeaker  100  sensed a threat. This can be beneficial, for example, if a person attempts to touch the electro-acoustic transducer  102  ( FIG. 1B ) while it is operating. In response, the shutter  106  ( FIG. 1A ) closes and the audio system  500  produces only low frequency components of the audio signal to provide an audible indication that a problem has been detected. 
     Other Implementations 
     In some cases, the shutter may be displaceable from a first, closed position to a second, open position, e.g., on power up, and may be further displaceable between the second, open position and a third, open position. For example, the opening (a/k/a “aperture”) defined by the shutter may increase when the audio volume increases. To avoid interfering with the operation of the electro-acoustic transducer, the opening may be larger than the electro-acoustic transducer in the second, open position and may increase in size as the volume of audio rendered by the loudspeaker increases, such that the entire front radiating surface of the electro-acoustic transducer remains exposed so long as the loudspeaker remains powered on. 
     While an exemplary shuttered loudspeaker has been described in which the shutter takes the form of a mechanical iris, other implementations are possible. For example, 
     In still other implementations, the shutter may include one or more blades that travel along a linear path to cover and uncover an aperture aligned with the electro-acoustic transducer. For example,  FIGS. 6A and 6B  illustrate an implementation of a shutter  600  which includes a pair of blades  602  that move linearly to cover ( FIG. 6A ) and to expose ( FIG. 6B ) an aperture  604  in a base ring  605 . The base ring  605  is fixedly attached to the loudspeaker housing (not shown). Motion of the two blades  602  are linked through a pair of racks  606   a ,  606   b  and a pinion gear  608  disposed therebetween. A first rack  606   a  is attached to a first one of the blades  602 , and a second rack  606   b  is attached to a second one of the blades  602 . Gear teeth  610   a ,  610   b  on the racks  606   a ,  606   b  engage mating teeth  212  on the pinion gear  608 . Motion of the shutter  600  can be driven by driving the pinion gear  608  with a rotary electric motor  614 . Alternatively, motion of the shutter  600  can be driven by driving one of the blades  602  along a linear path with a linear motor (not shown). While two blades are illustrated in  FIGS. 6A and 6B , a shutter comprising a single blade (e.g., a pinion gear driving a single blade to cover/uncover an aperture) is also possible. 
     Although an implementation has been described in which a shuttered loudspeaker is incorporated in a vehicle audio system, the shuttered loudspeakers herein may be utilized in other audio systems. For example,  FIG. 7  illustrates a home entertainment system  700  that includes a pair shuttered loudspeakers  702   a ,  702   b  which are connected to a receiver  704  (a/k/a tuner). For purposes of illustration, the left-hand loudspeaker  702   a  is shown in the first, closed position in which the electro-acoustic transducer  706   a  is covered, and the right-hand loudspeaker  702   b  is shown in the second, open position in which the electro-acoustic transducer  706   b  is exposed. In the example illustrated in  FIG. 7 , the loudspeakers  702   a ,  702   b  include mechanical iris type shutters  710 ; however, the shutters  710  may take any of the forms discussed above. 
     The loudspeakers  702   a ,  702   b  are configured such that their respective shutters  710  open in response to the loudspeaker  704  receiving a signal from the receiver  704 . In that regard, the loudspeakers  702   a ,  702   b  may each be equipped with control electronics, such as described above, for controlling operation of the shutters  710 . Alternatively, the receiver  704  may include control electronics for controlling the operation of the shutters  710 . 
     In some cases, the loudspeakers  702   a ,  702   b  may be provided with proximity sensors, such as described above with respect to  FIGS. 3A and 3B , which can be used to close the shutters  710  if an object is detected near one of the electro-acoustic transducers  706   a ,  706   b.    
     A number of implementations have been described. Nevertheless, it will be understood that additional modifications may be made without departing from the scope of the inventive concepts described herein, and, accordingly, other implementations are within the scope of the following claims.