Abstract:
A woofer that is capable of producing a flashing light show depending upon the volume and frequency of the sounds emitted thereby. The woofer includes at least one light emitting diode and a control circuit that are conveniently mounted on a printed circuit board at the center of the woofer at an inconspicuous location below a transparent dust cover so as to achieve a compact configuration without effecting the aesthetic appearance of the woofer. The woofer also includes a magnetic structure having at least one permanent magnet and at least one electromagnetic voice coil that is adapted to move in first and opposite directions towards and away from the permanent magnet depending upon the changing polarities of an alternating current that is supplied to the electromagnetic voice coil. An inside cone from a hollow shell that emits sounds to a listener is coupled to the electromagnetic voice coil so as to move in the first and opposite directions with the electromagnetic voice coil and thereby provide the listener with a powerful dynamic effect.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to speakers and, more particularly, to a woofer that is capable of producing a dynamic flashing light show depending upon the volume and frequency of the sound to be emitted thereby. 
     2. Background Art 
     A woofer is a well known type of speaker that reproduces audio sounds that are usually first amplified by an audio amplifier. However, the ornamental appearance of conventional woofers is independent of the sounds that are emitted therefrom. That is to say, the appearance of the woofer does not change regardless of the frequency and volume of the sounds that are heard by a listener. Therefore, the conventional woofer is, in and of itself, completely passive and has no effect on the emotions or feelings of the listener. 
     In certain cases, it has been known to associate an ornamental light emitting diode (LED) display with a speaker. Such speakers typically have control circuitry located on an exterior surface thereof. Since the LEDs are usually located far from the control circuitry, such LEDs require complicated circuitry having many connections which has heretofor resulted in malfunctions. In some cases, signal delays are introduced which cause the flashing light effect produced by the LEDs to be out of sync with the sound (e.g. music). In cases where the LEDs are placed around the outside of the speaker, the appearance of the speaker is often negatively effected. What is more, installation of these speakers is complicated in areas where little space is available, such as in a motor vehicle. Consequently, the conventional speakers having a flashing light capability are characterized by a large size, an undesirable crowded appearance and a flashing light display which does not always track the volume and/or frequency of the emitted sounds. 
     One example of a woofer which has a flashing light capability is available by referring to U.S. Pat. No. Des 442,945 issued May 29, 2001. 
     SUMMARY OF THE INVENTION 
     A woofer is disclosed having either one or two LEDs and a control circuit that are conveniently mounted on a printed circuit board at the center of the woofer at an inconspicuous location under a transparent dust cover so as to achieve a compact configuration without effecting the aesthetic appearance of the woofer. The woofer receives an AC input from the output of an audio amplifier. A diode rectifier transforms the AC input into a DC voltage for driving the LEDs. Accordingly, the LEDs are capable of generating a flashing light show depending upon the output of the audio amplifier and the volume and frequency of the sounds that are reproduced by the woofer. 
     The woofer includes a hollow shell that surrounds the printed circuit board on which the LEDs and control circuitry are mounted. The hollow shell has an inside cone and an outside frame that are joined together at a resilient (e.g. rubber) lip that extends around the outermost edge of the shell. The inner cone of the shell is attached (e.g. glued) to a voice coil housing that lies below the dust cover so as to enclose the LED printed circuit board. A single voice coil or dual voice coils are wound around the voice coil housing. The woofer has a magnetic structure including a T-yoke to carry a plurality of permanent magnets and an inner core around which the voice coil housing is slidably received. The voice coil, which is connected to AC input terminals of the woofer, receives an alternating current, such that when the polarity of the voice coil and the permanent magnets are identical, the voice coil will be attracted towards the permanent magnets. In this case, the voice coil housing around which the voice coil is wound will slide downwardly over the inner core of the magnetic structure so as to pull the resilient lip around the woofer shell radially inward. When the plurality of permanent magnets and the voice coil are at opposite polarities, the voice coil will be repelled by the magnets. In this case, the voice coil housing will slide upwardly over the inner core to push the resilient lip of the woofer shell radially outward. Accordingly, a dynamic push-pull magnetic effect is created that causes the woofer shell to be compressed and expanded in a manner that tracks the sounds being emitted by the woofer. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 shows the woofer of the present invention that is adapted to produce a dynamic flashing light show depending upon the volume and frequency of the sounds emitted thereby; 
     FIG. 2 is a side view of the woofer shown in FIG. 1; 
     FIG. 3 is a cross-section of the woofer of FIG. 1 having a pair of flashing light emitting diodes and a single voice coil; 
     FIG. 4 is a cross-section of the woofer of FIG. 1 having a single flashing light emitting diode and a pair of voice coils; and 
     FIGS. 5-7 show electronic circuits for converting an AC input voltage to a DC voltage by which to drive the light emitting diodes from the woofers of FIGS.  3  and  4 . 
    
    
     DETAILED DESCRIPTION 
     FIGS. 1 and 2 of the drawings show the woofer  1  of the present invention that is adapted to provide a flashing light show that tracks the amplitude and frequency of the sounds to be emitted therefrom. The woofer  1  includes a non-metallic base  3  that encloses a magnetic structure (designated  42  in FIGS.  3  and  4 ). The woofer  1  is shown having two pairs of AC input terminals  5 ,  6  and  7 ,  8 , although the advantages of this invention are also available by using only one pair of AC input terminals. The input terminals  5 ,  6  and  7 ,  8  are to be connected to receive an AC voltage from the AC output of an audio amplifier (not shown). As will be explained while referring to FIGS. 3-7, the AC input to the woofer  1  is rectified to a DC voltage in order to drive one or more LEDs (designated  32  and  32 - 1  in FIGS. 3 and 4) that are inconspicuously located at the center of the woofer  1  below a transparent dust cover  39  so as to consume little space without effecting the aesthetic appearance of the woofer. 
     The dust cover  39  extends across an elastic inside cone  38  that is spaced from an outside frame  38  of a hollow shell  35  (best shown in FIGS.  3  and  4 ). The inside cone  38  is joined to the outside frame  36  at a resilient lip  40  that extends around the outermost edge of the shell  35 . The lip  40  of shell  35  is surrounded by a relatively hard (e.g. plastic) rim  41  that extends circumferentially around the shell  35  of woofer  1 . As will now be disclosed, the elastic inside cone  38  of shell  35  surrounded by rim  41  will repeatedly collapse inwardly and expand outwardly in response to a push-pull magnetic effect in order to provide the woofer  1  with a dynamic appearance that also tracks the sounds emitted by woofer  1 . 
     FIGS. 3 and 4 of the drawings illustrate woofers  30  and  30 - 1  like that shown in FIGS. 1 and 2 having the capability of generating a flashing light show. The woofer  30  of FIG. 3 is provided with a pair of light emitting diodes (LEDs)  32  that are surrounded by a transparent voice coil housing  34  at the center of woofer  30 . In the embodiment shown in FIG. 3, the voice coil housing  34  is cylindrical in shape and adapted to be displaced relative to a soon to be described magnetic structure  42  of woofer  30 . A voice coil  55  is wrapped around the bottom of the voice coil housing  34 . Although a single voice coil  55  is shown in FIGS. 3 and 4, a dual voice coil winding may also be wrapped around the bottom of voice coil housing  34 . The voice coil  55  is connected by wires  10  and  12  (best shown in FIG. 2) to a first pair of AC input terminals  5  and  6 . A second voice coil (not shown) would be connected by wires  14  and  16  (of FIG. 2) to a second pair of AC input terminals  7  and  8 . 
     The woofer  30  includes a hollow, conically shaped shell  35  having an outside frame  36  and an inside cone  38  that lie in surrounding coaxial alignment with the voice coil housing  34 . The inside cone  38  of shell  35  is manufactured from a foam-like elastic material, such as polypropylene, or the like. The outside frame  36  of shell  35  is attached to the magnetic structure  42  of woofer  30  by way of a conical base  37 . The inside cone  38  of shell  35  is affixed to the voice coil housing  34  by means of a glue seam  54 . A force damping spider  33  that engages the outside frame  36  of shell  35  is affixed to voice coil housing  34  at the glue seam  54  so as to reduce the transmission of motion generated forces therebetween. A transparent dust cover  39  extends across the center of the inside cone  38  of shell  35  above the transparent voice coil housing  34  so as to permit the light generated by LEDs  32  to be visible therethrough. 
     The outside frame  36  and inside cone  38  of shell  35  are joined to one another at a resilient (e.g. rubber) lip  40  that surrounds the outermost edge of the shell  35 . Surrounding the elastic lip  40  of shell  35  is a circumferentially extending rim  41  of woofer  30  that is manufactured from a rigid material, such as plastic, or the like. 
     The magnetic structure  42  of woofer  30  includes a non-conductive (e.g. steel) T-yoke  44 . The T-yoke  44  has a hollow inner cylindrical core  46  and an outer magnet support ring  48  surrounding core  46 . The outside frame  36  of shell  35  is fixedly suspended above the top of the magnet support ring  48  of magnetic structure  42  by means of the aforementioned conical base  37  and suitable fasteners (e.g. screws)  50 . In this manner, and as will soon be described, the inside cone  38  of shell  35  is adapted to be displaced relative to the outside frame  36 . To this end, the bottom of the voice coil housing  34  around which the voice coil  55  is wrapped is slidably received around the cylindrical core  46  of T-yoke  44 . 
     The outer magnet support ring  48  of T-yoke  44  carries a plurality of permanent (e.g. ferrite) magnets  52 . The permanent magnets  52  and the voice coil  55  of FIGS. 3 and 4 are spaced from one another by an air gap  56 . Seated on top of and coaxially aligned with the hollow inner core  46  of T-yoke  44  so as to lie within the voice coil housing  34  is a ring-shaped printed circuit board  58 . Mounted around the ring-shaped printed circuit board  58  of the woofer  30  of FIG. 3 is the pair of LEDs  32  and the control circuitry (to be described in greater detail hereinafter when referring to FIGS. 5-7) by which to drive the LEDs  32  from a DC voltage. Printed circuit board  58  is attached to the inner core  46  of T-yoke  44  by mounting screws  60 , or the like. 
     The manner in which the foam-like inner cone  38  of shell  35  is displaced relative to the outside frame  36  thereof is now described while continuing to refer to FIGS. 3 and 4. As previously described when referring to FIGS. 1 and 2, the woofers  30  and  30 - 1  are powered by an AC voltage. A corresponding alternating current is conducted through wires  10  and  12  to the voice coil  55  that is wrapped around the voice coil housing  34 . Accordingly, the voice coil  55  will become an electromagnet having a polarity that changes with the alternating current. 
     When the polarity of the electromagnetic voice coil  55  is opposite the polarity of the permanent magnets  52 , an attractive magnetic field is established therebetween. In this case, the voice coil housing  34  to which the voice coil  55  is attached will be caused to slide along the inner core  46  of T-yoke  44  in a direction towards permanent magnets  52 . Inasmuch as the elastic inside cone  38  of shell  35  is attached to the voice coil housing  34 , a pulling force is applied to the resilient lip  40  of shell  35  via the inside cone  38 . Accordingly, the elastic inside cone  38  will collapse towards the outside frame  36 , and the resilient lip  40  at the outermost edge of shell  35  will be pulled radially inward and away from circumferentially extending rim  41  of woofer  30 . The spider damper  33  running across the shell  35  between the outside frame  36  and voice coil housing  34  opposes the compressive force that is generated in response to the movement of the inside cone  38  so that the outside frame  36  will remain substantially stationary. 
     When the polarity of the AC powered electromagnetic voice coil  55  changes so as to be identical to the polarity of the permanent magnets  52 , a repelling magnetic field is established therebetween. In this case, the voice coil housing  34  will be caused to slide in an opposite direction along the inner core  46  of T-yoke  44  so as to move away from the permanent magnets  52 . The inside cone  38  of shell  35  will now expand and the resilient lip  40  at the outermost edge of shell  35  is pushed outwards and towards the rim  41  of woofer  30 . In this regard, it may be appreciated that the constantly alternating polarity of the voice coil  55  produces a push-pull magnetic effect, whereby to cause a compression and expansion of the shell  35  such that the elastic lip  40  thereof repeatedly moves back and forth relative to the position of the rim  41  so as to create a dynamic woofer effect in combination with a flashing light show. 
     FIG. 4 of the drawings shows a woofer  30 - 1  having a shell  35  and a magnetic structure  42  that are identical to those of the woofer  30  in FIG.  3 . Therefore, like reference numerals have been used to identify identical components in FIGS. 3 and 4. In the case of FIG. 4, the woofer  30 - 1  includes a single LED  32 - 1  on printed circuit board  58  as opposed to the pair of LEDs  32 . 
     FIG. 5 of the drawings illustrates an AC circuit  64  by which to drive a single LED such as that designated  32 - 1  for the woofer  30 - 1  of FIG.  4 . The circuit  64  has a single pair of AC input terminals  66  and  68  and a diode rectifier to drive LED  32 - 1 . The circuit  64  will be used for a woofer having a single voice coil (designated  55  in FIG.  4 ). The input terminals  66  and  68  of circuit  64  are connected to receive AC audio output signals from an audio amplifier (not shown). The circuit  64  includes a pair of rectifying diodes  69  and  70  that transform the input AC voltage to a DC voltage to drive LED  32 - 1 . Each rectifying diode  69  and  70  is respectively connected between an AC input terminal  66  and  68  and one terminal of LED  32 - 1 . A conventional resistor bridge, comprising resistors R 1 -R 4 , is connected between rectifying diode  69  and LED  32 - 1 . 
     FIG. 6 of the drawings illustrates another AC circuit  72  by which to drive a single LED  32 - 1 . In this case, the circuit  72  has two pairs of AC input terminals  73 ,  74  and  76 ,  77 . What is more, the circuit  72  is adapted for use in a woofer having dual voice coils (not shown). Each pair of input terminals  73 ,  74  and  76 ,  77  is connected to a corresponding pair of AC audio output terminals from an audio amplifier (not shown). The circuit  72  includes a four diode, full rectifier bridge, comprising rectifier diodes  79 - 82 , that transforms the input AC voltage to a DC voltage to drive LED  32 - 2 . A conventional resistor bridge, comprising resistors R 1 -R 4 , is connected between one output terminal of the diode rectifier bridge and LED  32 - 2 . 
     For increased brightness, FIG. 7 of the drawings illustrates another AC circuit  84  by which to drive a pair of LEDs, such as those designated  32  in FIG.  3 . Like the circuit  72  of FIG. 6, the AC circuit  84  of FIG. 7 has two pairs of AC input terminals  86 ,  87  and  89 ,  90  and a four diode, full rectifier bridge, comprising diodes  92 - 95 , that transforms the AC voltage from input terminals  86 ,  87  and  89 ,  90  to a DC voltage to drive LEDs  32 . The LEDs  32  are connected in electrical series with one another, and a conventional resistor bridge, comprising resistors R 1 -R 4 , is connected in the series path between the LEDs  32 . 
     Because the LEDs  32  and  32 - 1  of the circuits  64 ,  72  and  84  of FIGS. 5-7 are driven by rectified AC audio output signals from an audio amplifier, the brightness of the LEDs will be controlled by the output power of the audio amplifier. Moreover, the LEDs will flash only where there is an audio output signal from the audio amplifier. That is to say, to enhance the decorative effect provided at the center of the woofers  30  and  30 - 1  of FIGS. 3 and 4, the frequency and magnitude of the flashing light show produced by the LEDs will vary with the volume and frequency of the sound to be reproduced by the woofers. What is more, the light visible to a listener can be selectively controlled depending upon the value of the resistors R 1 -R 4  of the resistor bridges in circuits  64 ,  72  and  84 . Because the LEDs and their control circuits are housed on a printed circuit board that is located at the center of the shell  35 , a compact and aesthetically pleasing woofer is now available to provide the listener with a powerful feeling. By virtue of the foregoing, the listener will be treated to a dynamic flashing light show that tracks the sounds that are emitted from the woofer.