Patent ID: 12262162

DETAILED DESCRIPTION

The present invention is directed to improved electroacoustic drivers that can be utilized in loudspeaker systems that utilize bidirectional force electromagnet transducers or piezoelectric transducers. The present invention is applicable to electroacoustic drivers for use at all audible frequencies. However, the electroacoustic drivers of the present invention are particularly advantageous for in the lower frequency ranges, such as below 1000 Hz, and more particularly below 500 Hz, and even more particularly below 300 Hz.

Transducers with Motion Amplification

The present invention utilizes a mechanism inside that is capable of controllably moving diaphragms of large relative surface area utilizing electromagnets and/or piezoelectric actuators. While electromagnets and/or piezoelectric actuators are not typically used for electroacoustic drivers mechanisms (since the amount of movement is relatively small) in comparison to the what is generally required, it has been discovered that these can be utilized to provide for significantly smaller, lighter, more efficient, and better sounding electroacoustic speakers. It has been found that the electroacoustic drivers of the present invention can produce at least four times the sound pressure as compared to conventional electro-dynamic drivers of the same size and weight. Moreover, the sound pressure is much higher at the lowest end of the audible frequency range (20 Hz to 60 Hz), which is generally the most difficult range for loudspeakers to emit strong audible sound.

Use of improved electroacoustic drivers of the present invention further provides for smaller and lighter electroacoustic drivers (as compared to conventional electro-dynamic drivers), which is advantageous for loudspeaker systems that are mobile (carried by hand) and also for use in vehicles (cars, boats, etc.)

The controlled motion of moveable panels can be performed with bidirectional force electromagnets or piezoelectric actuators.

FIG.4is an illustration of a frontal view of electroacoustic speaker400of the present invention, which utilizes a sealed chamber. The electroacoustic speaker400has an exterior portion401and a moveable panel403a(that can be made of a polymer, such as plastic material) that is connected to the exterior portion401with an expandable boundary element402a(which is generally an elastic material, such as rubber). Per the orientation ofFIG.4, the height of electroacoustic speaker400is in the y-direction (running down to up in the plane of the sheet ofFIG.4) and the width of electroacoustic speaker is in the x-direction (running left to right in the plane of the sheet ofFIG.4).FIG.4shows two cross-sections (A-A′ and B-B′) that are pointing in the negative x-direction. The z-direction is perpendicular to the plane of the sheet ofFIG.4and is running outward toward the viewer of the sheet ofFIG.4. This x-, y-, z-direction orientation is maintained inFIGS.5-11, to assist in a better understanding of the figures.

FIG.5is an illustration of a cross-section of electroacoustic speaker400taken along line B-B′ shown inFIG.4. Per the orientation ofFIG.5, the y-direction is running down to up in the plane of the sheet ofFIG.5, and the z-direction runs from right to left in the plane of the sheet ofFIG.5. The x-direction perpendicular to the plane of the sheet ofFIG.5and is running inward away from the viewer of the sheet ofFIG.5.

FIG.6is an illustration of the perspective view of the electroacoustic speaker400. Per the orientation ofFIG.5, the y-direction is running down to up in the plane of the sheet ofFIG.6. The x-direction and z-direction are directed in the orientation shown by the x-y-z axis shown inFIG.6. To further orientedFIG.6, cross-sections A-A′ and B-B′ fromFIG.4are shown inFIG.6.

Referring toFIGS.5-6, these figures show the electroacoustic mechanism utilized in electroacoustic speaker400. The electroacoustic mechanism utilizes a bidirectional force electromagnet that includes ferromagnetic disc501positioned between two electromagnets502-503. As shown inFIGS.5-6, disc501and electromagnets502-503are annular in shape. However, other shapes can be implemented. The electromagnets502-503are stationary with respect to electroacoustic speaker400, and can be utilized to move the disc upward or downward in the y-direction. A person of skill in the art would readily understand how to utilize a bidirectional force electromagnet to so move the ferromagnetic disc, including the circuitry required for such electromagnet system. For instance, the bidirectional force electromagnet transducer arrangement is similar to that shown in U.S. Pat. No. 5,920,138.

As discussed below inFIGS.8-9, the bidirectional movement of the ferromagnetic disc in an electromagnet transducer can be utilized directly to move the panels in an electroacoustic speaker. However, the mechanism shown inFIGS.5-6utilizes motional amplification mechanisms such as lever arms to multiply the amount of movement of the panels of the electroacoustic speaker.

As discussed above,FIG.4shows electroacoustic speaker400has an exterior portion401and a panel403a(that can be made of a polymer, such as plastic material) that is connected to the exterior portion401with an expandable boundary element402a(which is generally an elastic material, such as rubber). While not shown inFIG.4(due to its orientation),FIGS.5-6shows that there is an opposing panel403bthat is connected to the exterior portion401with an expandable boundary element402b. Opposing panel403band expandable boundary element402bare generally made of the same materials as panel403aand expandable boundary element402aand have the same dimensions. By doing so, any inertial forces that apply to panel402aand panel402bare equal but in opposite directions (which perFIGS.5-6would be in the z-direction) and thus will cancel each other so that the inertial forces of the overall electroacoustic speaker400are approximately zero. This force cancellation has important benefits that include preventing movement of the loudspeaker during its use.

A bidirectional force electromagnet transducer, such as one having ferromagnetic disc501and electromagnets502-503shown inFIGS.5-6, will need significantly more electrical power to move the disc larger distances. This is because the magnetic force is decreased by a factor of the square of the distance between disc501and electromagnets502-503. Thus, there is a significant advantage in limiting the movement of the disc501to a small distance (i.e., a small gap for the electromagnet), such as a maximum distance in the range of 0.5 mm to 2 mm, and, more particularly, a maximum distance in the range of 0.5 mm to 1 mm.

The magnetic force produced by a bidirectional force electromagnet transducer is normally proportional to the square of the current supplied to one of the two electromagnets on either side of disc501. Stated another way, the magnetic force increases as the square of the input current to the electromagnet (the force is non-linear with current). One way to make the bidirectional force electromagnet transducer produce a force that is linear with input current is to supply electromagnet502and503with a constant current that is about half of the maximum current; then to increase the current of electromagnet502by a particular percentage (i.e., by x %) while decreasing the current to electromagnet503by the same particular percentage (i.e., by x %). This approach makes the magnetic force approximately linear with changes in electromagnet current and thus makes controlling the bidirectional force electromagnet transducer much less complicated. A position sensor can be used to track the position of disc501relative to electromagnets502-503. This position information can be used in conjunction with an active feedback loop to make sure that disc501does not make physical contact with electromagnets502-503and also insure that disc501is moving the correct amount required to faithfully reproduce a desired audio output. A position sensor can also track the motion of the moveable panels to insure that the panels are moving the correct amount relative to the desired audio output (since a lever arm mechanism may introduce some differences in motion between disc501and one or more moveable panels).

While the disc501is moved in this maximum distance (between electromagnets502-503), it is the distance of that panel403aand opposing panel403bmoves, and their surface area (the area of panel403aand opposing panel403b) which generate the sound and intensity of sound that is emitted by electroacoustic speaker400.

As shown inFIG.5-6, when disc501is moved, this moves block505upward/downward in the y-direction (per the orientation ofFIGS.4-6). Block505is pivotably connected to lever arm507a, which is pivotably connected to block504athat is positioned on the interior of panel403a. Block504ais also pivotably connected to lever arm508a, which is pivotably connected to block506that is attached to exterior portion401on the opposite side of electroacoustic speaker400. A symmetrical arrangement is also shown in which block505is pivotably connected to lever arm507b, which is pivotably connected to block504bthat is positioned on the interior of opposing panel403b. Block504bis also pivotably connected to lever arm508b, which is pivotably connected to block506. It should be noted that while the connection to disc501is shown inFIGS.5-6through block505, disc501can be alternatively pivotably connected to lever arms507a-507bdirectly or through some other mechanism. Likewise, the lever arms507a-508aand507b-508bcan be alternatively pivotably connected to panel403aand opposing panel403b, respectively, directly or through some other mechanism. And, likewise, the lever arms508a-508bcan be alternatively pivotably connected to exterior portion401on the opposite side of electroacoustic speaker400, directly or through some other mechanism.

By such arrangement, the movement of disc501in the y-direction will cause a movement of panel403aand opposing panel403bin the z-direction. As oriented inFIGS.5-6, the movement of disc501in the positive y-direction will cause panel403ato move outward relative to electroacoustic speaker400in a positive z-direction and will also cause opposing panel403bto move outward relative to electroacoustic speaker400in a negative z-direction. The opposite movement of disc501(i.e., movement in the negative y-direction) will cause panel403ato move inward relative to electroacoustic speaker400in a negative z-direction and will also cause opposing panel403bto move inward relative to electroacoustic speaker400in a positive z-direction. Important in this movement is that the arrangement of lever-arms507a-508aand507b-508bwill cause a greater magnitude of movement of panel403aand opposing panel403bin the z-direction than the movement of disc505in the y-direction. I.e., the movement will be in the range of 2-5 times greater. For instance, while the disc501may be moved a distance of 0.5 mm, the panel403aand opposing panel403bmay be moved in the z-direction a distance of 1.0 mm (which depends on the angle at which these lever arms are connected). Moreover, the large force produced by the electromagnet transducer will result in the panel403aand opposing panel403bbeing efficiently moved, even though these panels have significantly greater surface area than the bidirectional force electromagnet actuator.

Moreover, block506can also be moved by a second bidirectional force electromagnet actuator (such as one having a disc and electromagnets similar to disc501and electromagnets502-503) that can also be utilized in the mechanism to move panel403aand opposing panel403beven further inward and outward (i.e., in the positive and negative z-direction).

Because bidirectional force electromagnet transducers can be inherently unstable, they may require a position sensor (that monitors the movement of the ferromagnetic disc directly or indirectly such as looking at panel movement) and active feedback to work well. The disc can run into one of the electromagnets in the absence of a position sensor and an active feedback loop to monitor disc motion. Accordingly, electroacoustic speaker400can further have a position sensor509that monitors the movement of the panel403awith a feedback loop, so as to better control the movement of panel403a(and coordinately opposing panel403b) for further control and improved sound quality of electroacoustic speaker400. Position sensor509can alternatively monitor the movement of block505to ensure that disc501does not contact either electromagnet502or electromagnet503.

For example, an embodiment of electroacoustic speaker400can have the following dimensions:

Area of each panel403a-403b:98 cm2(7 cm×14 cm).

Peak air volume displacement: 58 cc.

Peak chamber pressure: +/−6240 Pascal.

Lever arm ratio (ratio of movement of panel403ain the z-direction to the movement of disc501in the y-direction): 1.7.

Outside radius of electromagnets502-503: 14.2 mm.

Area of electromagnets502-503: 6.3 cm2.

At these dimensions, the area of the two panels403a-403bthat are driven by one bidirectional force electromagnet transducer is 196 cm2, which is 31 times the area of electromagnets502-503. This ratio is significantly higher than the area ratio of moveable cone area divided by voice coil actuator area of conventional electro-dynamic drivers, which is around 4.4 times. Thus, the area ratio of moveable panel area divided by electromagnet transducer area is 7 times higher than a conventional electro-dynamic driver. Significant advantages are achieved by having a panel to electromagnet panel area ratio of at least 10.

The maximum excursion of a typical electro-dynamic driver is +/−5 mm. For electroacoustic speaker400having the above dimensions, the maximum excursion of disc501is +/−0.42 mm, which is 11.9× less than traditional a comparable electro-dynamic driver due to the 7× area ratio times the 1.7× lever ratio. The relatively small excursion of disc501results in low power consumption of electroacoustic speaker400because the power consumption of a bidirectional force electromagnet transducer increases as the square of this disc excursion.

As shown from the above, disc501needs to move much less than conventional electro-dynamic drivers to produce as much or more sound pressure. Since bidirectional force electromagnet transducer average power consumption increases as the square of its peak displacement, it is very important to keep bidirectional force electromagnet transducer peak displacement under approximately +/−1 mm.

Another important fact is that bidirectional force electromagnet transducer mass and average power are highly sensitive to lever arm ratio. A higher lever arm ratio results in lower power consumption but higher bidirectional force electromagnet transducer mass.

It is believed that a lever arm ratio of 2-4 is a good compromise between mass and power. However, the optimal lever arm ratio will vary with each speaker design.

Levered Electroacoustic Drivers Utilizing Piezoelectric Actuators

FIG.7is an alternative electroacoustic speaker taken in the same cross-section of electroacoustic speaker400shown inFIG.4(taken along line B-B′ shown inFIG.4). In this alternative embodiment, the bidirectional force electromagnet transducer has been replaced by a piezoelectric actuator791. Moreover, a second piezo-electric actuator792is utilized and positioned in the arrangement shown inFIGS.5-6in place of block506. A spacer793is used for positioning piezoelectric actuator791appropriately. Such spacer can be also used for piezoelectric actuator792. (Moreover, such a spacer can likewise be utilized in the arrangement shown inFIGS.5-6). The piezoelectric transducer792is shown with its own motion amplifying lever arm due to the small excursions of piezoelectric transducers (typically just 10-50 microns). This lever arm enables the piezoelectric transducer to move approximately 0.5 millimeters.

The piezoelectric actuators can then be utilized similar to the utilization of the bidirectional force electromagnet transducer(s) discussed above with respect toFIGS.5-6.

Direct Drive Bidirectional Force Electromagnet Transducers

FIGS.8-9are each illustrations of a loudspeaker utilizing other alternative electroacoustic driver mechanisms (but without the lever arms described above). In these embodiments, the movement of the panels is done directly by bidirectional force electromagnet transducers. While the amount of panel movement is not as great (due to the absence of the lever arms), there remain advantages for using these transducers, particularly for low frequency sound applications. Again, these embodiments take advantage of moving panels with high surface area with only a small movement by the bidirectional force electromagnet transducers.

InFIG.8, loudspeaker890has four panels893a-893d, each of which is bounded by expandable boundary elements892a-892d, respectively. These can be made of similar materials as discussed above for panel403aand expandable boundary element402adescribed above. In the orientation ofFIG.8, panels893a-893dmove outward and inward relative to loudspeaker890in the z-direction. By symmetry, the inertial forces caused by the movement of these panels will cancel out with one another, which will reduce the mechanical vibrations of loudspeaker890.

In loudspeaker890, there are four bidirectional force electromagnet transducers, each of which has a ferromagnetic disc and a two electromagnets, similar as described above for the electroacoustic speaker400described above. Specifically, (a) the movement of panel893ais controlled by the bidirectional force electromagnet transducer made up of disc891aand electromagnets894a-895a, (b) the movement of panel893bis controlled by the bidirectional force electromagnet transducer made up of disc891band electromagnets894b-895b, (c) the movement of panel893cis controlled by the bidirectional force electromagnet transducer made up of disc891cand electromagnets894c-895c, and (d) the movement of panel893dis controlled by the bidirectional force electromagnet transducer made up of disc891dand electromagnets894d-895d.

InFIG.9, loudspeaker990has four panels993a-993d, each of which is bounded by expandable boundary elements992a-992d, respectively. These are like the four panels893a-893dand expandable boundary elements892a-892dand can be made of similar materials as discussed above for panel403aand expandable boundary element402adescribed above. In the orientation ofFIG.9(and similar the arrangement inFIG.8), panels993a-993dmove outward and inward relative to loudspeaker990in the z-direction. By symmetry, the inertial forces caused by the movement of these panels will cancel out with one another, which is advantageous to the use of loudspeaker990.

In loudspeaker990, there are two bidirectional force electromagnet transducers, each of which has a disc and a two electromagnets, similar as described above for the electroacoustic speaker400described above. Specifically, (a) the movement of panels993aand993cis controlled by the bidirectional force electromagnet transducer made up of disc991aand electromagnets994a-995aand (b) the movement of panels993band993dis controlled by the bidirectional force electromagnet transducer made up of disc991band electromagnets994b-995b. When disc991ais moved in the z-direction (by utilizing electromagnets994a-995ato create a magnetic force), it applies a force in the positive or negative z-direction to beam996a, which in turn coordinately applies a force in the same positive or negative z-direction to each of beams997aand997c(which then move panels993aand993c, respectively, in the same positive or negative z-direction).

By symmetry, when disc991bis moved in the z-direction (by utilizing electromagnets994b-995bto create a magnetic force), it applies a force in the negative or positive z-direction to beam996b, which in turn coordinately applies a force in the same negative or positive z-direction to each of beams997band997d(which then move panels993band993d, respectively, in the same negative or positive z-direction).

Generally, by having disc991aand disc991bmove concurrently in the same but opposite z-directions, this will result in a net zero overall inertial forces applied to loudspeaker990. For instance, if disc991ais moved in the positive z-direction and disc991bis moved in an equal amount in the negative z-direction, this will result in panels993a-993dall moving outward from loudspeaker990with panels993aand993cmoving in a positive z-direction and panels993band993dmoving in an equal but negative z-direction.

Alternative Embodiment Utilizing Lever Arm

FIGS.10-11are illustrations of loudspeaker1000that utilizes two bidirectional force electromagnet transducers with a compact motion amplification mechanism. Loudspeaker1000has many of the same features as loudspeaker990with (a) four panels1003a-1003dof loudspeaker1000corresponding, respectively, to panels993a-993dof loudspeaker990, (b) expandable boundary elements1002a-1002dof loudspeaker1000corresponding, respectively, to expandable boundary elements992a-992dof loudspeaker990; (c) the bidirectional force electromagnet transducer made up of disc1001aand electromagnets1004a-1005ain loudspeaker1000corresponding to the bidirectional force electromagnet transducer made up of disc991aand electromagnets994a-995ain loudspeaker990; and (d) the bidirectional force electromagnet transducer made up of disc1001band electromagnets1004b-1005bin loudspeaker1000corresponding to the bidirectional force electromagnet transducer made up of disc991band electromagnets994b-995bin loudspeaker990.

When disc1001ais moved in the z-direction (by utilizing electromagnets1004a-1005ato create a magnetic field), it applies a force in the positive or negative z-direction at hinge1008aof hinged beam1006a. As hinged beam1006ais pivoted on each side by fulcrums1009-1010, this applies a force in the opposite z-direction to each of beams1007aand1007c(which then move panels1003aand1003c, respectively, in the opposite z-direction of the movement of disc1001a). By locating the fulcrums1009-1010closer to hinge1008athan beams1007aand1007c, there is an increase in the movement of panels1003aand1003cas compared to the movement of disc1001a.

By symmetry, when disc1001bis moved in the z-direction (by utilizing electromagnets1004b-1005bto create a magnetic field), it applies a force in the negative or positive z-direction at hinge1008bof hinged beam1006b. As hinged beam1006bis pivoted on each side by fulcrums1009-1010, this applies a force in the opposite z-direction to each of beams1007band1007d(which then move panels1003band1003d, respectively, in the opposite z-direction of the movement of disc1001b). By locating the fulcrums1009-1010closer to hinge1008bthan beams1007band1007d, there is an increase in movement of the1003band1003das compared to the movement of disc1001b.

Generally, by having disc1001aand disc1001bmove concurrently in the same but opposite z-directions, this will result in a net zero overall inertial forces applied to loudspeaker1000. For instance, if disc1001ais moved in the negative z-direction and disc1001bis moved in an equal amount in the positive z-direction, this will result in panels1003a-1003dall moving outward from loudspeaker1000with panels1003aand1003cmoving in a positive z-direction and panels1003band1003dmoving in an equal but negative z-direction. Thus, to move panels1003a-1003doutward, discs1001a-1001bare both moved inward relative to loudspeaker1000, while, to move panels1003a-1003dinward, discs1001a-1001bare both moved outward relative to loudspeaker1000.

FIG.11is an illustration of a frontal view of the loudspeaker1000. It should be noted that this looks similar to the frontal view of each of loudspeakers890and990.

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. Accordingly, other embodiments are within the scope of the following claims. 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.

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.

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.

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.

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

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.

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.

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.

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.