WO2020041358A1

WO2020041358A1 - Compact electroacoustic transducer, loudspeaker system and method of use thereof

Info

Publication number: WO2020041358A1
Application number: PCT/US2019/047325
Authority: WO
Inventors: Joseph F. Pinkerton; William Neil Everett
Original assignee: Clean Energy Labs, Llc
Priority date: 2018-08-20
Filing date: 2019-08-20
Publication date: 2020-02-27

Abstract

An improved loudspeaker that has a plurality of stacks of cards having electrostatic transducers, in which a low capacitance PCB stator is utilized within the cards. The stators have metal that is not energized and thus exhibit low capacitance, as compared to stainless steel stators, and thus provide lower power consumption and longer battery runtime, such as for portable speakers.

Description

COMPACT ELECTROACOUSTIC TRANSDUCER, LOUDSPEAKER SYSTEM AND METHOD OF USE THEREOF

RELATED PATENT APPLICATIONS

[0001] This application is a PCT Application claiming priority to U. S. Provisional Patent Serial No. 62/719,912, filed on August 20, 2018, to Joseph F. Pinkerton et al ., entitled“Compact Electroacoustic Transducer And Loudspeaker System And Method Of Use Thereof.”

[0002] This application is related to U.S. Patent Application Serial No. 16/510,669, filed on July 12, 2019, and is entitled“Compact Electroacoustic Transducer and Loudspeaker System and Method Of Use Thereof’ (the“ Pinkerton’669 Application”).

[0003] This application is related to U.S. Patent Application Serial No. 16/510,702, filed on July 12, 2019, and is entitled“Cover-Baffle-Stand System For Loudspeaker System And Method Of Use Thereof’ (the“ Pinkerton’702 Application”).

[0004] This application is related to U.S. Patent No. 10,250,997, entitled “Compact Electroacoustic Transducer and Loudspeaker System and Method Of Use Thereof,” which issued April 2, 2019, to Pinkerton et al. (the“ Pinkerton ’997 Patent’) from U.S. Patent Application Serial No. 15/333,488, filed on October 25, 2016.

[0005] This application is also related to U.S. Patent No. 9,167,353, entitled“Electrically Conductive Membrane Pump/Transducer And Methods To Make And Use Same,” which issued October 20, 2015, to Pinkerton et al. (the“ Pinkerton ’353 Patent”) from U.S. Patent Application Serial No. 14/309,615, filed on June 19, 2014, which is a continuation-in-part to U.S. Patent Application Serial No. 14/161,550, filed January 22, 2014.

[0006] This application is also related to U.S. Patent No. 9,143,868, entitled“Electrically Conductive Membrane Pump/Transducer And Methods To Make And Use Same,” which issued September 22, 2015 to Pinkerton et al. (the“ Pinkerton’868 Patent”) from U.S. Patent Application No. 14/047,813, filed October 7, 2013, which is a continuation-in-part of International Patent Application No. PCT/2012/058247, filed October 1, 2012, which designated the United States and claimed priority to provisional U. S. Patent Application Serial No. 61/541,779, filed September 30, 2011.

[0007] This application is also related to U.S. Patent No. 9,924,275, entitled“Loudspeaker Having Electrically Conductive Membrane Transducers,” which issued March 30, 2018 to Pinkerton et al. (the“ Pinkerton ’275 Patent”) from U.S. Patent Application Serial No. 15/017,452, filed February 5, 2016, which claimed priority to provisional U.S. Patent Application Serial No. 62/113,235, filed February 6, 2015.

[0008] This application is also related to United States Patent No. 9,826,313, entitled “Compact Electroacoustic Transducer And Loudspeaker System And Method Of Use Thereof,” which issued November 21, 2017, to Pinkerton et al. , (the“ Pinkerton’313 Patent’) from U.S. Patent Application Serial No. 14/717,715, filed May 20, 2015.

[0009] United States Patent Appl. Serial No. 15/647,073, filed July 11, 2017, to Joseph F. Pinkerton et al. , and entitled“Electrostatic Membrane Pump/Transducer System And Methods To Make And Use Same,” (the“ Pinkerton’073 Application”).

[0010] This application is also related to International Patent Application No.

PCT/US19/30438, filed May 2, 2019, entitled“Loudspeaker System and method Of Use Therefor,” to Pinkerton et al. (the“ Pinkerton PCT’438 Application”). which designated the United States and claimed priority to provisional U.S. Patent Application Serial No. 62/666,002, filed May 2, 2018

[0011] This application is also related to International Patent Application No.

PCT/US19/33088, filed May 20, 2019, entitled“Compact Electroacoustic Transducer And Loudspeaker System And Method Of Use Thereof,” to Badger, Pinkerton, and Everett (the “ Badger PCT Ό88 Application”), which designated the United States and claimed priority to provisional U.S. Patent Application Serial No. 62/673,620, filed May 18, 2018.

[0012] All of these above-identified patent applications are commonly assigned to the Assignee of the present invention and are hereby incorporated herein by reference in their entirety for all purposes.

TECHNICAL FIELD

[0013] The present invention relates to loudspeakers, and in particular, to loudspeakers having an electrostatic transducer or an array of electrostatic transducers. The electrically conductive transducers generate the desired sound by the use of pressurized airflow.

BACKGROUND

[0014] Conventional audio speakers compress/heat and rarify/cool air (thus creating sound waves) using mechanical motion of a cone-shaped membrane at the same frequency as the audio frequency. Most cone speakers convert less than 10% of their electrical input energy into audio energy. These speakers are also bulky in part because large enclosures are used to muffle the sound radiating from the backside of the cone (which is out of phase with the front- facing audio waves). Cone speakers also depend on mechanical resonance; a large“woofer” speaker does not efficiently produce high frequency sounds, and a small“tweeter” speaker does not efficiently produce low frequency sounds.

[0015] Thermoacoustic (TA) speakers use heating elements to periodically heat air to produce sound waves. TA speakers do not need large enclosures or depend on mechanical resonance like cone speakers. However, TA speakers are terribly inefficient, converting well under 1% of their electrical input into audio waves.

[0016] The present invention relates to an improved loudspeaker that includes an array of electrically conductive membrane transducers such as, for example, an array of polyester-metal membrane pumps.

[0017] Graphene membranes (also otherwise referred to as“graphene drums”) have been manufactured using a process such as disclosed in Lee et al. Science, 2008, 321, 385-388. PCT Patent Appl. No. PCT/US09/59266 (Pinkerton) (the “ Pinkerton ‘266 PCT Application”) described tunneling current switch assemblies having graphene drums (with graphene drums generally having a diameter between about 500 nm and about 1500 nm). PCT Patent Appl. No. PCT/US11/55167 (Pinkerton et al.) and PCT Patent Appl. No. PCT/US 11/66497 (Everett et al.) further describe switch assemblies having graphene drums. PCT Patent Appl. No. PCT/US11/23618 (Pinkerton) (the“PCT US11/23618 Application”) described a graphene- drum pump and engine system.

[0018] FIGS. 1-5 are figures that have been reproduced from FIGS. 27-32 of the Pinkerton ’353 Patent. As set forth in the Pinkerton’353 Patent :

[0019] FIGS. 1A-1E depict an electrically conductive membrane pump/transducer 2700 that utilizes an array of electrically conductive membrane pumps that cause a membrane 2702 to move in phase. FIGS. 1 A-1B are cross-sectional views of the pump/transducer that includes electrically conductive members 2701 (in the electrically conductive membrane pumps) and a speaker membrane 2702. Speaker membrane 2702 can be made of a polymer, such as PDMS. Each of the electrically conductive membrane pumps has a membrane 2701 that can deflect toward downward and upwards. Traces 2605 are a metal (like copper, tungsten, or gold). The electrically conductive membrane pumps also have a structural material 2703 (which can be plastic, FR4 (circuit board material), or Kapton® polyimide film (DuPont EISA)) and support material 2704 that is an electrical insulator (like oxide, FR4, or Kapton® polyimide film). Support material 2704 can be used to support the pump membrane, support the stator and also serve as the vent structure. Integrating these functions into one element makes device 2700 more compact than it would be with multiple elements performing these functions. All of the non-membrane elements shown in FIG. 1A-1E can be made from printed circuit boards or die stamped sheets, which enhances manufacturability.

[0020] Arrows 2706 and 2707 show the direction of fluid flow (i.e., air flow) in the pump/transducer 2700. When the electrically conductive membranes 2701 are deflected downward (as shown in FIG. 1A), air will flow out of the pump/transducer device 2700 (from the electrically conductive membrane pumps) as shown by arrows 2706. Air will also flow from the cavity 2708 into the electrically conductive membrane pumps as shown by arrows 2707 resulting in speaker membrane 2702 moving downward. When the electrically conductive membranes 2701 are deflected upwards (as shown in FIG. IB), air will flow into the pump/transducer device 2700 (into the electrically conductive membrane pumps) as shown by arrows 2706. Air will also flow into the cavity 2708 from the electrically conductive membrane pumps as shown by arrows 2707 resulting in speaker membrane 2702 moving upward.

[0021] FIG. 1C is an overhead view of pump/transducer device 2700. Line 2709 reflects the cross-section that is the viewpoint of cross-sectional views of FIGS. 1A-1B. FIGS. 1D-1E shows the flow of air (arrows 2707 and 2706, respectively) corresponding to the deflection downward of electrically conductive membranes 2701 and speaker membrane 2702 (which is shown in FIG. 1A). The direction of arrows 2707 and 2706 in FIGS. 1D-1E, respectively, are reversed when the deflection is upward (which is shown in FIG. IB).

[0022] The basic operation for pump/transducer 2700 is as follows. A time-varying stator voltage causes the pump membranes 2701 to move and create pressure changes within the speaker chamber 2708. These pressure changes cause the speaker membrane 2702 to move in synch with the pump membranes 2701. This speaker membrane motion produces audible sound.

[0023] The ability to stack pumps in a compact way greatly increases the total audio power. Such a pump/transducer stacked system 2800 is shown in FIG. 2.

[0024] For the embodiments of the present invention shown in FIGS. 1A-1E and 2, the individual pump membranes 2701 can be smaller or larger than the speaker membrane 2702 and still obtain good performance. [0025] Pump/transducer system 2700 (as well as pump/transducer speaker stacked system 2800) can operate at higher audio frequencies due to axial symmetry (symmetrical with respect to the speaker membrane 2702 center). Each membrane pump is approximately the same distance from the speaker membrane 2702 which minimizes the time delay between pump membrane motion and speaker membrane motion (due to the speed of sound) which in turn allows the pumps to operate at higher pumping/audio frequencies.

[0026] It also means that pressure waves from each membrane pump 2701 arrive at the speaker membrane 2702 at about the same time. Otherwise, an audio system could produce pressure waves that are out of synch (due to the difference in distance between each pump and the speaker membrane) and thus these waves can partially cancel (lowering audio power) at certain pumping/audio frequencies.

[0027] Pump/transducer system 2700 (as well as pump/transducer speaker stacked system 2800) further exhibit increased audio power. Since all the air enters/exits from the sides of the membrane pump, these pumps can be easily stacked (such as shown in FIG. 2) to significantly increase sound power. Increasing the number of pump stacks (also referred to“pump cards”) from one to four (as shown in FIG. 2) increases audio power by approximately a factor of 16 As can be seen in FIG. 2, the gas within the chamber is sealed by the membrane pump membranes and the speaker membrane. The gas in the sealed chamber can be air or another gas such as sulfur hexafluoride that can withstand higher membrane pump voltages than air.

[0028] Audio output is approximately linear with electrical input (resulting in simpler/cheaper electronics/sensors). Another advantage of the design of pump/transducer 2700 is the way the pump membranes 2701 are charged relative to the gates/stators. These are referred to as “stators,” since the term“gate” implies electrical switching. Pump/transducers have a low resistance membrane and the force between the stator and membrane is always attractive. This force also varies as the inverse square of the distance between the pump membrane and stator (and this characteristic can cause the audio output to be nonlinear/distorted with respect to the electrical input). The membrane can also go into“runaway” mode and crash into the stator. Thus, in practice, the amplitude of the membrane in pump/transducer is limited to less than half of its maximum travel (which lowers pumping speed and audio power).

[0029] The issues resulting from non-linear operation are solved in the design of pump/transducer 2700 by using a high resistance membrane (preferably a polymer film like Mylar with a small amount of metal vapor deposited on its surface) that is charged by a DC voltage and applying AC voltages to both stators (one stator has an AC voltage that is 180 degrees out of phase with the other stator). A high value resistor (on the order of 10⁸ ohms) may also be placed between the high resistance membrane (on the order of 10⁶ to 10¹² ohms per square) and the source of DC voltage to make sure the charge on the membrane remains constant (with respect to audio frequencies).

[0030] Because the pump membrane 2701 has relatively high resistance (though low enough to allow it to be charged in several seconds) the electric field between one stator and the other can penetrate the charged membrane. The charges on the membrane interact with the electric field between stator traces to produce a force. Since the electric field from the stators does not vary as the membrane moves (for a given stator voltage) and the total charge on the membrane remains constant, the force on the membrane is constant (for a give stator voltage) at all membrane positions (thus eliminating the runaway condition and allowing the membrane to move within its full range of travel). The electrostatic force (which is approximately independent of pump membrane position) on the membrane increases linearly with the electric field of the stators (which in turn is proportional to the voltage applied to the stators) and as a result the pump membrane motion (and also the speaker membrane 2702 that is being driven by the pumping action of the pump membrane 2701) is linear with stator input voltage. This linear link between stator voltage and pump membrane motion (and thus speaker membrane motion) enables a music voltage signal to be routed directly into the stators to produce high quality (low distortion) music.

[0031] FIG. 3 depicts an electrically conductive membrane pump/transducer 3000 that is similar to the pump/transducers 2700 and 2900, in that it utilizes an array of electrically conductive membrane pumps. Pump/transducer 3000 does not utilize a speaker membrane (such as in pump/transducer 2700) or a structure in place of the speaker membrane (such as in pump/transducer 2900). Pump/transducer 3000 produces substantial sound even without a speaker membrane. Applicant believes the reason that there is still good sound power is that the membrane pumps are compressing the air as it makes its way out of the inner vents (increasing the pressure of an time-varying air stream increases its audio power). Arrows 3001 show the flow of air through the inner vents. The pump/transducer 3000 has a chamber that receives airflow 3001 and this airflow exhausts out the chamber by passing through the open area (the chamber exhaust area) at the top of the chamber. In order to produce substantial sound the total area of the membrane pumps must be at least 10 times larger than the chamber exhaust area.

[0032] FIG. 3 also shows an alternate vent configuration that has holes 3003 in the stators that allow air to flow to separate vent layers. The cross-sectional airflow area of the vents (through which the air flow is shown by arrows 3001) is much smaller than the pump membrane area (so that the air is compressed). FIG. 3 also shows how a simple housing 3004 can direct the desired sound 3005 toward the listener (up as shown in FIG. 3) and the undesired out of phase sound away from the listener (down as shown in FIG. 3). The desired sound 3005 is in the low sub-woofer range to mid-range (20 Hz to about 3000 Hz).

[0033] FIG. 4 depicts an electrically conductive membrane pump/transducer 3100 that is the pump/transducer 3000 that also includes an electrostatic speaker 3101 (which operates as a “tweeter”). An electrostatic speaker is a speaker design in which sound is generated by the force exerted on a membrane suspended in an electrostatic field. The desired sound 3102 from the electrostatic speakers 3101 is in a frequency in the range of around 2 to 20 KHz (generally considered to be the upper limit of human hearing). Accordingly, pump/transducer 3100 is a combination system that includes a low/mid-range speaker and a tweeter speaker.

[0034] FIG. 5 depicts an electrically conductive membrane pump/transducer 3200 that is the pump/transducer 3100 that further includes the speaker membrane 3202 (such as in pump/transducer 2700).

[0035] FIGS. 6A-6C and 7 are figures that have been reproduced from FIGS. 16A-16C and 17 of the Pinkerton’313 Patent. As set forth in the Pinkerton’313 Patent :

[0036] FIG. 6A illustrates an electroacoustic transducer 1601 (“ET,” which can also be referred to as a“pump card”) and its solid stator 1602 (shown in more detail in FIG. 6B). Vent fingers 1603 are also shown in ET 1601. FIG. 6B is a magnified view of ET 1601 and shows how there are membranes 1604 and 1605 on each side of shared stator 1602.

[0037] FIG. 6C shows the electroacoustic transducer 1601 having a single stator card before trimming off the temporary support 1606 that supports the vent fingers 1603 (as shown in FIGS. 6A-6B). This process enables a low cost die stamping construction. Parts can be stamped out (which is very low cost), then epoxied together, and then the part 1606 that temporarily holds all the vent fingers 1603 in place can be quickly stamped off or trimmed off.

[0038] FIG. 7 is an exploded view of ET 1601. From top to bottom: FIG. 7 shows an electrically conductive membrane 1604, a first metal frame 1701, first non-conductive vent member 1702 (with its 23 vent fingers 1703), solid metal stator 1602, second non-conductive vent member 1704, and second metal frame 1705. (The second membrane is not shown). These parts can be joined together with epoxy, double-sided tape, sheet adhesive or any other suitable bonding process. After membrane 1604 is bonded to frame 1701 its entire outside edge (peripheral edge) is supported by frame 1701. [0039] FIGS. 8A-8B are figures that have been reproduced from FIGS. 8A-8B of the Badger ’088 PCT Application. As set forth in the Badger Ό88 PCT Application.

[0040] FIG. 8A illustrates an exploded view of an electroacoustic transducer 801 that has two pump cards. This is similar to the electroacoustic transducer 1601 shown in FIG. 7. However, electroacoustic transducer 801 does not have metal frames 1701 and 1705. I.e ., the double stack cards of electroacoustic transducer 801 lack any frames.

[0041] From top to bottom: FIGS. 8A-8B shows a first non-conductive vent member 802 (with its 23 vent fingers), a first electrically conductive membrane 803, a second non-conductive vent member 804, a first solid metal stator 805, a third non-conductive vent member 806, a second electrically conductive membrane 807, a fourth non-conductive vent member 808, and a second solid metal stator 809. As before, these parts can be joined together with epoxy, double-sided tape, sheet adhesive or any other suitable bonding process. FIG. 8B shows the electroacoustic transducer 801 after its parts (as shown in FIG. 8A) have been bonded together.

[0042] The membranes (membranes 803 and 807) are supported by the pair of non-conductive vent membranes above and below the membrane. For example, first non-conductive vent member 802 supports a portion of a first electrically conductive membrane 803 and second non-conductive vent member 804 supports the other portion of first electrically conductive membrane 803. No non-conductive vent by itself can support the electrically conductive membrane.

[0043] This absence of the frames from electroacoustic transducer 801 was significant and provided advantageous and unexpected results. The frames in the earlier pump cards (such as the electroacoustic transducer 1601 shown in FIG. 7) were expensive, difficult to make (the metal spans being both thin and narrow) and also had a tendency of causing electrical arcs to the stator. By removing the frames, the electrical arcing has been eliminated in electroacoustic transducer 801. [0044] FIGS. 9A-9B are figures that has been reproduced from FIGS. 9A-9B of the Pinkerton Ό73 Application. As set forth in the Pinkerton Ό73 Application :

[0045] FIGS. 9A-9B show a speaker 900 that utilizes EVMP card stacked arrays 901-903. Each of the EVMP card stacked arrays has a face area, such as face area 909 of EVMP card stacked array 903. Each of EVMP card stacked array 901-903 has two face areas, on one side of speaker 900 (such as face area 909 for EVMP card stacked array 903) and the other side of the speaker 900 (which is hidden in the view of FIGS. 9A-9B). Air enters and exits the EVMP card stacked arrays through each of the EVMP card stacked array face areas (In fact air enters and exits the EVMPs in the EVMP card stacked arrays through each of the face areas of the EVMP cards).

[0046] By way of example, the EVMP card stacked array 901 can be a stacked array of 30 cards. Each card in the EVMP card stacked array can be about 1 mm thick so the EVMP card stacked array 901 stack of cards is about 30 mm thick. The face area of one EVMP card (in the EVMP card stacked array) is 1 mm times the stack width (for example 300 mm), which calculates to be 300 mm² per card for each face of the EVMP card (which means the combined area of the faces of an EVMP card in the EVMP card stacked array is 600 mm² per EVMP card). Thus, for an EVMP card stacked array having 30 cards, this calculates to be 18,000 mm² for the total face area of the EVMP card stacked array. I.e ., the area of face area 909 would be 9,000 mm², as it is one of the two faces of EVMP card stacked array 903.

[0047] The membrane area of that same EVMP card is the depth of the card (for example 20 mm) times the card width (which, again, for example, is 300 mm). This calculates to be 6,000 mm² per EVMP card, which is 10 times larger than the face area of the EVMP card. Again, for a 30 card stacked array in an EVMP card stacked array, this calculates to a total membrane area of 180,000 mm². This means that total membrane area of the EVMP card stacked array (such as EVMP card stacked array 903) is around 10 times the total face area of the EVMP card stacked array. It is worthwhile to note that speaker 900 shows three EVMP card stacked arrays (namely EVMP card stacked arrays 901-903), which can be run at different electrical phases.

[0048] The speaker 900 also utilizes two (one for each of the two stereo channels) “conventional” electrostatic audio actuator card stacks 904-905 (conventional in that the membrane pumping frequency equals the produced audio frequency). I.e ., conventional card stacks 904-905 are stacks of electrostatic tweeter cards. The speaker 900 also includes electronics and battery 906 with control buttons 907. Speaker 900 has three EVMP card stacked arrays 901-903, and although all of the cards within these EVMP card stack arrays are similar in structure, each EVMP card stack arrays can be driven at a different electrical phase. For instance, the EVMPs in each of EVMP card stacked arrays 901-903 can have an electrical drive voltage phase of 0°, 120°, and 240°, respectively. I.e ., the EVMPs in EVMP card stacked array 901 can be operated at 0°, the EVMPs in EVMP card stacked array 902 can be operated at 120°, and the EVMPs in EVMP card stacked array 903 can be operated at 240°.

[0049] FIGS. 10 and 11A-11B are figures that has been reproduced from FIGS. 4 and 5A-5B of the Pinkerton’002 Application. As set forth in the Pinkerton '002 Application:

[0050] FIG. 10 is an illustration of a dipole speaker 400 that has all electrostatic transducers. Sound comes out from side 401 and oppositely phased sound comes out the other side (not shown). It also has control buttons 407 and MEMs microphone ports 408 (with the MEMs microphones located behind microphone ports 408). The MEMs microphones are for example Knowles SPK0412HM4H-B-7 (Knowles Electronics, LLC, Itasca, Illinois) and are operably connected to a power source and a CPET on the speaker 400. The power source is generally the same power source as used for the speaker and the CPET controls the electrostatic transducers.

[0051] The MEMs microphone ports 408 on the speaker 400 have been positioned along the null sound plane (NSP) of the speaker 400 (which null sound plane 503 shown in FIG. 5B).

[0052] FIG. 11A is a top view of speaker 400, showing only the top. Opposite sides 401 and 501 are shown. Sound emits from side 401 and oppositely phased sound out side 501 in speaker 400 (which makes it a dipole speaker).

[0053] FIG. 11B is a magnified view of box 502 shown in FIG. 5A. The null sound plane 503 for speaker 400 is shown. The MEMs microphone ports are positioned along this null sound plane 503.

SUMMARY OF THE INVENTION

[0054] The present invention relates to an improved loudspeaker that utilizes an improved stator in the electrostatic transducers utilized in the loudspeakers disclosed and taught in the Pinkerton ’669 Application , the Pinkerton ’702 Application , the Pinkerton’ 997 Patent , the Pinkerton ’353 Patent , the Pinkerton ’868 Patent , the Pinkerton ’275 Patent , the Pinkerton ’313 Patent , the Pinkerton ’073 Application , the Pinkerton PCT’438 Application , and the Badger PCT Ό88 Application (collectively the“ Pinkerton Patents and Applications”). The improved stators are made with a printed circuit board process (PCB), and have advantages over earlier stators in that they can have lower capacitance (and thus lower power consumption and longer battery runtime, such as for a portable speaker).

[0055] In general, in one aspect, the invention features a system that includes a plurality of electroacoustic transducers. At least some of the electroacoustic transducers are each an electronic transducer that includes a stator that includes a metal and an insulating material. A first portion of the metal is electrically connected to a source of alternating polarity voltage. A second portion of the metal is not electrically connected to the source of alternating polarity voltage.

[0056] Implementations of the invention can include one or more of the following features:

[0057] The stator can have a patterned layer of the metal sandwiched between two layers of the insulating material.

[0058] The insulating material can include fiberglass or plastic material. [0059] The patterned layer can have a thickness between 9 and 36 microns.

[0060] Each of the two layers of the insulating material can have a thickness of between 50 and 100 microns.

[0061] The stator can have a capacitance that is at least 1.3 times less than a stator of same dimensions made of stainless steel.

[0062] The metal can include copper.

[0063] Each of the electroacoustic transducer having the stators can further include one or more moveable membranes. The patterned layer of the metal can be a pattern in which substantially all of the first portion of the metal in each of the stators is positioned directly under or above the one or more moveable membranes.

[0064] The second portion the metal in each of the stators is adhered to the insulating material.

[0065] Each of the stators can include teeth/fmgers.

[0066] The teeth/fmgers can be not electrically connected to the source of alternating polarity voltage.

[0067] The stators can be made using a PCB process.

[0068] The systems can be a loudspeaker system.

[0069] The loudspeaker system can be a portable loudspeaker system.

[0070] In general, in another aspect, the invention features a method that includes making an electroacoustic transducer that includes a stator. The stator includes metal and an insulating material. The method further includes connecting a first portion of the metal to a source of alternating polarity voltage. The second portion of the metal is not connected to the source of alternating polarity voltage.

[0071] Implementations of the invention can include one or more of the following features:

[0072] The method can include making a plurality of electroacoustic transducers in which wherein at least some of the electroacoustic transducers each include a stator that includes the metal and the insulating material. The method can further include connecting a first portion of the metal in each stator to the source of alternating polarity voltage, in which the second portion of the metal in each stator is not connected to the source of alternating polarity voltage.

[0073] The stator can be made by sandwiching a patterned layer of the metal between two layers of the insulating material.

[0074] The insulating material can include fiberglass or plastic material.

[0075] The patterned layer can have a thickness between 9 and 36 microns.

[0076] Each of the two layers of the insulating material can have a thickness of between 50 and 100 microns.

[0077] The stator can have a capacitance that is at least 1.3 times less than a stator of same dimensions made of stainless steel.

[0078] The metal can include copper.

[0079] The step of making the electroacoustic transducer can include positioning the stator by a moveable membrane. The patterned layer of the metal can be a pattern in which substantially all of the first portion of the metal in the stator is positioned directly under or above the moveable membrane.

[0080] The stators are made using a PCB process.

[0081] The method can further include making a system that includes the plurality of electroacoustic transducers.

[0082] The step of making a plurality of stators stator can include making each of the stators in the plurality of stators by sandwiching a patterned layer of the metal between two layers of the insulating material.

[0083] The insulating material can include fiberglass or plastic material.

[0084] Each of the electroacoustic transducers can include one or more moveable membranes. The patterned layer of the metal can be a pattern in which substantially all of the first portion of the metal in each of the stators is positioned directly under or above the one or more moveable membranes.

[0085] The second portion of the metal in each of the stators can be adhered to the insulating material.

[0086] Each of the stators can include teeth/fmgers.

[0087] The teeth/fmgers can be not electrically connected to the source of alternating polarity voltage.

[0088] The system can be a loudspeaker system.

[0089] The loudspeaker system can be a portable loudspeaker system.

DESCRIPTION OF DRAWINGS

[0090] FIGS. 1A-1E (which are reproduced from the Pinkerton ’353 Patent) depict an electrically conductive membrane pump/transducer that utilizes an array of electrically conductive membrane pumps that cause a membrane to move in phase. FIGS. 1A-1B depict cross-section views of the pump/transducer. FIGS. 1C-1E depict overhead views of the pump/transducer.

[0091] FIG. 2 (which is reproduced from the Pinkerton’353 Patent) depicts an electrically conductive membrane pump/transducer that has a stacked array of electrically conductive membrane pumps.

[0092] FIG. 3 (which is reproduced from the Pinkerton’353 Patent) depicts an electrically conductive membrane pump/transducer that utilizes an array of electrically conductive membrane pumps that operates without a membrane or piston.

[0093] FIG. 4 (which is reproduced from the Pinkerton’353 Patent) depicts an electrically conductive membrane pump/transducer 3100 that utilizes an array of electrically conductive membrane pumps and that also includes an electrostatic speaker.

[0094] FIG. 5 (which is reproduced from the Pinkerton’353 Patent) depicts an electrically conductive membrane pump/transducer 3200 that utilizes an array of electrically conductive membrane pumps that cause a membrane to move in phase and that also includes an electrostatic speaker.

[0095] FIG. 6A (which is reproduced from the Pinkerton ’313 Patent) illustrates an electroacoustic transducer (“ET,” which is also referred to as a“pump card”) and its solid stator.

[0096] FIGS. 6B (which is reproduced from the Pinkerton’313 Patent) is a magnified view of the electroacoustic transducer of FIG. 6A.

[0097] FIG. 6C (which is reproduced from the Pinkerton ’313 Patent) illustrates the electroacoustic transducer of FIG. 6A having a single stator card before trimming off the vent fingers.

[0098] FIG. 7 (which is reproduced from the Pinkerton’313 Patent) is exploded view of the electroacoustic transducer of FIG. 6A.

[0099] FIG. 8A (which is reproduced from the Badger’088 PCT Application) illustrates an exploded view of an electroacoustic transducer.

[0100] FIG. 8B (which is reproduced from the Badger Ό88 PCT Application) illustrates the electroacoustic transducer shown in FIG. 8A in fabricated form.

[0101] FIGS. 9A-9B (which are reproduced from the Pinkerton Ό73 Application) illustrate a loudspeaker with stacked arrays of electrostatic venturi membrane-based pump/transducer (EVMP) cards.

[0102] FIG. 10 (which is reproduced from the Pinkerton’438 PCT Application) illustrates a dipole loudspeaker having electrostatic transducers.

[0103] FIGS. 11A-11B (which are reproduced from the Pinkerton ’438 PCT Application) illustrate the null sound plane (NSP) of the speaker of FIG. 10.

[0104] FIGS. 12A-12B are photographs of stators (having widths 21 mm and 12 mm, respectively) made of stainless steel that were utilized in embodiments of the loudspeakers disclosed and taught in the Pinkerton Patents and Applications.

[0105] FIGS. 13A-13B are photographs of stators (widths 21 mm and 12 mm, respectively) utilized in loudspeakers of the present invention.

[0106] FIG. 14A is an illustration of a stator (all layers) of the present invention.

[0107] FIG. 14B is an illustration of the top copper and FR-4 layers of the stator illustrated in

FIG. 14A.

[0108] FIG. 14C is an illustration of the copper interlayer and FR-4 layer of the stator illustrated in FIG. 14A.

DETAILED DESCRIPTION

[0109] The present invention relates to a loudspeaker having improved pump cards that each include an array of electrically conductive membrane transducers (such as polyester-metal membrane pumps). The array of electrically conductive membrane transducers combine to generate the desired sound by the use of pressurized airflow. In the present invention, a plurality of stacks of cards having electrostatic transducers is employed such as disclosed and taught in the Pinkerton Patents and Applications , which utilize a new stator. The stators employed in electrostatic transducers disclosed and taught in Pinkerton Patents and Applications at times can have drawbacks in certain applications. For example, such stators (such as stators 1201 and 1202, having widths of 21 mm and 12 mm, and shown in FIGS. 12A-12B, respectively) are made almost entirely of energized conductive material that includes energized conductive material in contact with a non-conductive vent member and this can lead to a relatively high capacitance (which increases power consumption and reduces battery runtime of the electrostatic transducers). Another potential negative is that these stators are stamped (requiring a specialized and, typically, expensive die), electroplated, laminated with an insulating material and then trimmed to remove excess lamination material. These stators are also relatively heavy. Such stators can be made at very low cost.

[0110] An alternative stator has been discovered in which these new stators are made with a printed circuit board process (PCB). A thin (9 to 36 micron) patterned layer of copper is sandwiched between two thin (50 to 100 microns) layers of a fiberglass such as FR4.

[0111] Examples of such stators, such as stators 1301 and 1302 (having widths of 21 mm and 12 mm, respectively) and are shown in FIGS. 13A-13B. An advantage of these new stators is that they have lower capacitance (and thus lower power consumption and longer battery runtime for a portable speaker). The 12 mm PCB stator 1302 was measured to have a capacitance that is l.3x less than the 12 mm stainless steel stator 1202. 1.e., stator 1302 will draw l.3x less current as compared to stator 1202. As shown in FIGS. 13A-13B, the only metal 1303 (copper in this case) that is connected to a power source is positioned directly under the moveable membrane (in a complete electroacoustic card). The part of the stator that is adhered to the FR4 or plastic vent structure is not powered by the circuit and thus does not contribute to capacitance.

[0112] Another advantage is manufacturing simplicity: the complete stator can be purchased from a PCB supplier. If the PCB copper 1303 is thin enough (less than 50 microns), these stators 1301-1302 can also be lighter than the stainless steel stators 1201-1202.

[0113] Yet another advantage is that these PCB stators 1301-1302 can withstand higher voltages than the stainless stators 1201-1202 due to thicker insulation, higher dielectric constant material and the absence of sharp metal features (which are well known to initiate electrical arcing) that are connected to a voltage. As shown in FIGS. 13A-13B, the stator teeth/fmgers 1306 of the PCB stators 1301-1302 are not electrically connected).

[0114] Another element of the PCB stator, which is shown on stator 1301 is an array of small copper features 1304 that limit membrane-stator contact area (and thus reduce audible noise if the membrane touches stator 1301) and prevents the membrane from directly touching the FR4 (which reduces electrostatic charging and associated small but temporary reduction in audio power). These small copper features 1304 are not electrically connected to any circuit.

[0115] FIG. 14A shows a 21 mm PCB stator 1401. FIG. 14B shows the top copper 1404 and FR-4 layers of stator 1401. FIG. 14C shows the copper interlayer 1403 and FR-4 layer of stator 1401. The bottom of the stator is 50-100 microns of FR4 with etched copper (9-36 microns thick) stator features 1404 on top. There is another 50-100 micron FR4 part that is adhered to the top copper of the bottom part and optionally has the small copper features on top of this second FR4 part as described above. Thus, the copper that is connected to a voltage is encapsulated between two sheets of insulating FR4.

[0116] FIGS. 13A-13B and FIGS. 14A-14C also show gold-plated copper connection rings 1305 and 1405, respectively. These rings 1305 and 1405 make it easy to solder wires to the stators.

[0117] While embodiments of the invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the invention. The embodiments described and the examples provided herein are exemplary only, and are not intended to be limiting. Many variations and modifications of the invention disclosed herein are possible and are within the scope of the invention. The scope of protection is not limited by the description set out above, but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims.

[0118] The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated herein by reference in their entirety, to the extent that they provide exemplary, procedural, or other details supplementary to those set forth herein.

[0119] Amounts and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a numerical range of approximately 1 to approximately 4.5 should be interpreted to include not only the explicitly recited limits of 1 to approximately 4.5, but also to include individual numerals such as 2, 3, 4, and sub-ranges such as 1 to 3, 2 to 4, etc. The same principle applies to ranges reciting only one numerical value, such as“less than approximately 4.5,” which should be interpreted to include all of the above-recited values and ranges. Further, such an interpretation should apply regardless of the breadth of the range or the characteristic being described.

[0120] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which the presently disclosed subject matter belongs. Although any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of the presently disclosed subject matter, representative methods, devices, and materials are now described.

[0121] Following long-standing patent law convention, the terms“a” and“an” mean“one or more” when used in this application, including the claims.

[0122] Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term“about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in this specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

[0123] As used herein, the term“about” and“substantially” when referring to a value or to an amount of mass, weight, time, volume, concentration or percentage is meant to encompass variations of in some embodiments ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1%, in some embodiments ±0.5%, and in some embodiments ±0.1% from the specified amount, as such variations are appropriate to perform the disclosed method.

[0124] As used herein, the term“substantially perpendicular” and“substantially parallel” is meant to encompass variations of in some embodiments within ±10° of the perpendicular and parallel directions, respectively, in some embodiments within ±5° of the perpendicular and parallel directions, respectively, in some embodiments within ±1° of the perpendicular and parallel directions, respectively, and in some embodiments within ±0.5° of the perpendicular and parallel directions, respectively.

[0125] As used herein, the term“and/or” when used in the context of a listing of entities, refers to the entities being present singly or in combination. Thus, for example, the phrase“A, B, C, and/or D” includes A, B, C, and D individually, but also includes any and all combinations and subcombinations of A, B, C, and D.

Claims

WHAT IS CLAIMED IS

1. A system comprising a plurality of electroacoustic transducers, wherein at least some of the electroacoustic transducers are each an electronic transducer that comprises a stator that comprises:

(a) a metal, wherein

(i) a first portion of the metal is electrically connected to a source of alternating polarity voltage, and

(ii) a second portion of the metal is not electrically connected to the source of alternating polarity voltage; and

(b) an insulating material.

2. The system of Claim 1, wherein the stator has a patterned layer of the metal sandwiched between two layers of the insulating material.

3. The system of Claim 2, wherein the insulating materials comprises fiberglass or plastic material.

4. The system of Claim 2, wherein the patterned layer has a thickness between 9 and 36 microns.

5. The system of Claim 4, wherein each of the two layers of the insulating material has a thickness of between 50 and 100 microns.

6. The system of Claim 2, wherein the stator has a capacitance that is at least 1.3 times less than a stator of same dimensions made of stainless steel.

7. The system of Claim 1, wherein the metal comprises copper.

8. The system of Claim 1, wherein

(a) each of the electroacoustic transducer having the stators further comprise one or more moveable membranes; and

(b) the patterned layer of the metal is a pattern in which substantially all of the first portion of the metal in each of the stators is positioned directly under or above the one or more moveable membranes.

9. The system of Claim 1, wherein the second portion of the metal in each of the stators is adhered to the insulating material.

10. The system of Claim 1, wherein each of the stators comprises teeth/fmgers.

11. The system of Claim 10, wherein the teeth/fmgers are not electrically connected to the source of alternating polarity voltage.

12. The system of Claim 1, wherein the stators are made using a PCB process.

13. The system of Claim 1, wherein the system is a loudspeaker system.

14. The system of Claim 13, wherein the loudspeaker system is a portable loudspeaker system.

15. A method comprising:

(a) making an electroacoustic transducer comprising a stator, wherein the stator comprises metal and an insulating material; and

(b) connecting a first portion of the metal to a source of alternating polarity voltage, wherein a second portion of the metal is not connected to the source of alternating polarity voltage.

16. The method of Claim 15, wherein the method comprises

(a) making a plurality of electroacoustic transducers, wherein at least some of the electroacoustic transducers each comprise a stator that comprises the metal and the insulating material; and

(b) connecting a first portion of the metal in each stator to the source of alternating polarity voltage, wherein the second portion of the metal in each stator is not connected to the source of alternating polarity voltage.

17. The method of Claim 15, wherein the stator is made by sandwiching a patterned layer of the metal between the insulating material.

18. The method of Claim 17, wherein the insulating material comprises fiberglass or plastic material.

19. The method of Claim 17, wherein the patterned layer has a thickness between 9 and 36 microns.

20. The method of Claim 15, wherein each of the two layers of the insulating material has a thickness of between 50 and 100 microns.

21. The method of Claim 15, wherein the stator has a capacitance that is at least 1.3 times less than a stator of same dimensions made of stainless steel.

22. The method of Claim 15, wherein the metal comprises copper.

23. The method of Claim 15, wherein

(a) the step of making the electroacoustic transducer comprises positioning the stator by a moveable membrane; and

(b) the patterned layer of the metal is a pattern in which substantially all of the first portion of the metal in the stator is positioned directly under or above the moveable membrane.

24. The method of Claim 16, wherein the stators are made using a PCB process.

25. The method of Claim 16 further comprising making a system comprising the plurality of electroacoustic transducers.

26. The method of Claim 25, wherein the step of making a plurality of stators comprises making each of the stators in the plurality of stators by sandwiching a patterned layer of the metal between two layers of the insulating material.

27. The method of Claim 26, wherein the insulating material comprises fiberglass or plastic material.

28. The method of Claim 25, wherein

(a) each of the electroacoustic transducers comprises one or more moveable membranes; and

29. The method of Claim 28, wherein the second portion of the metal in each of the stators is adhered to the insulating material.

30. The method of Claim 25, wherein each of the stators comprises teeth/fmgers.

31. The method of Claim 30, wherein the teeth/fmgers are not electrically connected to the source of alternating polarity voltage.

32. The method of Claim 25, wherein the system is a loudspeaker system.

33. The method of Claim 32, wherein the loudspeaker system is a portable loudspeaker system.