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| PlanotTM Speaker |
A new way
The shape of things to come
Rigid and fixed
How it works
Plans to build it
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licensing inquiries to: info@planotspeaker.com
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FIG. 1A - Place your cursor over a number and see a label.
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| Click in image below to see detail. |
| Patent Pending
Planot technology is the solution. How it works... Below is a description of the operation of the Planot driver. |
| Operation FIG. 1A shows a side view of an implementation of the Planot driver. The vertical diaphragm 14A would have a triangular cross section and be attached to bearings 12 and 18 at both the top and bottom of the diaphragm. Bearings 12 and 18 are attached to a spindle 22 to which are attached two voice coils 46a 46b. Click on FIG.1A to see a popup which shows the complete motor, minus the magnetic homing and the filters on the side, and also an overhead cut away view. This type of voice coil, a rotary voice coil swing arm actuator, is most often employed in modern hard drives to position the heads and also in scientific instruments. Its operating parameters are well understood. In this implementation of the Planot driver there are two opposed voice coils to balance inertial forces and electrical impedances. In popup (click on FIG. 1A) the top of the motor frame and the top pole pieces and the top magnets have been removed for clarity. The two bearings and are held in place by the motor frame of rigid nonmagnetic material. The motor frame 31 serves as a support for the pole pieces 44 and the magnets 48 for the motor. The motor frame is fixed to a base 26. Offset from the diaphragm 14A and the motor frame 31 and fixed to the base 26 is a top support mast 42. Attached to the top support mast 42 is a top support arm 10 which is fixed to the top support mast 42 on one end and to the bearing 12 on the other end. The rigid structure created by the top support mast 42 and the top support arm 10 and the base 26 provides a rigid brace for the bearing 12 and therefore the top end of the diaphragm. The top support mast 42 bottom is fixed as far as the dimensions of the base 26 allows away from the bottom of the diaphragm 14A. A large homing magnet 38 is held in place by a magnet bracket 36 and is fixed to the motor frame 31. A small homing magnet 40 is placed on the side(s) of the diaphragm 14A and whose pole faces the same pole of the large homing magnet 38 held in place by the bracket 36. A pair of wires 30A run from the voice coils to a set of plugs 34 on the base 26 for the attachment of speaker cables (not shown) from the output of an audio amplifier (not shown). A Wire 30B show thick covered extension of the wires 30A outside of the motor frame. A set of at least three feet 28 are fixed to the underside of the base 26 to prevent the base 26 from moving due to the inertial forces generated by the voice coil and diaphragm assemblies as they pivot. An air permeable filter 16 is attached to the open sides of the motor frame 31 to allow air circulation for cooling of the voice coils 46a 46b at the same time preventing particulate matter, especially ferrous material, from being drawn into the inside of the motor frame 31. The electrical signal from the audio amplifier (not shown) is fed to the voice coils 46a 46b by means of a speaker cable attached at (not shown) the 34 speaker cable connectors. The electrical signal varies in frequency and amplitude. This signal causes a likewise varying magnetic field to be generated in the voice coils 46a 46b which interacts with the static magnetic fields of the permanent magnets 48 to move the diaphragm 14A that the voice coils 46a 46b are rigidly fixed. When moving under the force of the voice coils 46a 46b the diaphragm's 14A vertical surfaces sweep equally through the air and reproduces the amplitude and frequency information in the electrical signal. When the long sides of the diaphragm 14A pivots it creates positive sound pressure as a consequence of the geometry of the diaphragm 14A. The whole surface of all of the long sides push equally against the surrounding air at the same time. Another embodiment of the Planot driver would allow for separate drivers which would be optimized to produce sound in separate discrete segments of the audible frequency range. Planot technology can be implemented for a tweeter and a woofer. Such drivers could be designed for a specific frequency range by designing for a specific high frequency cut off in the horizontal polar response and also optimize the surface area and weight for the same frequency range. The diaphragm for the high frequencies, 5,000 cps to 18,000 cps would use a shorter length and lighter diaphragm. A driver to produce only the middle frequencies from 500 cps to 5,000 cps would have a larger surface area. The small dimension of each face would be wider because it would only need a 360 degree polar response up to slightly higher than 5,000 cps crossover point where its high frequency response begins to diminish under the control of a crossover. The driver for the low frequencies need only have faces with widths to accommodate a high frequency slightly higher than say 500 cps. The lower cut off for a woofer can accommodate a greater mass because the transient response requirements diminish as the high frequency response of a driver goes lower. The lower its highest frequency the slower it will have to pivot. These individual drivers could be stacked vertically to maintain the line source vertical polar response as in the full-range implementation. The pop up image (click on FIG. 1A) shows a possible arrangement for the homing magnets that center the voice coil diaphragm assembly. |
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