US3803521A - Electromechanical band-pass filter - Google Patents
Electromechanical band-pass filter Download PDFInfo
- Publication number
- US3803521A US3803521A US00366590A US36659073A US3803521A US 3803521 A US3803521 A US 3803521A US 00366590 A US00366590 A US 00366590A US 36659073 A US36659073 A US 36659073A US 3803521 A US3803521 A US 3803521A
- Authority
- US
- United States
- Prior art keywords
- flat coil
- pass filter
- coil
- permanent magnet
- ferromagnetic part
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 230000005294 ferromagnetic effect Effects 0.000 claims abstract description 41
- 230000005291 magnetic effect Effects 0.000 claims abstract description 30
- 239000004020 conductor Substances 0.000 claims abstract description 27
- 230000004907 flux Effects 0.000 claims description 13
- 238000004804 winding Methods 0.000 claims description 13
- 239000000463 material Substances 0.000 claims description 8
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 4
- 230000005415 magnetization Effects 0.000 claims description 4
- 239000003302 ferromagnetic material Substances 0.000 claims description 3
- 230000010355 oscillation Effects 0.000 claims description 3
- 229910000531 Co alloy Inorganic materials 0.000 claims description 2
- 229910052742 iron Inorganic materials 0.000 claims description 2
- 230000008878 coupling Effects 0.000 description 9
- 238000010168 coupling process Methods 0.000 description 9
- 238000005859 coupling reaction Methods 0.000 description 9
- 230000005520 electrodynamics Effects 0.000 description 7
- 229910045601 alloy Inorganic materials 0.000 description 2
- 239000000956 alloy Substances 0.000 description 2
- KPLQYGBQNPPQGA-UHFFFAOYSA-N cobalt samarium Chemical compound [Co].[Sm] KPLQYGBQNPPQGA-UHFFFAOYSA-N 0.000 description 2
- 238000013016 damping Methods 0.000 description 2
- 229910000938 samarium–cobalt magnet Inorganic materials 0.000 description 2
- 230000002463 transducing effect Effects 0.000 description 2
- 101100454194 Caenorhabditis elegans mei-1 gene Proteins 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 240000007049 Juglans regia Species 0.000 description 1
- JATPLOXBFFRHDN-DDWIOCJRSA-N [(2r)-2-acetyloxy-3-carboxypropyl]-trimethylazanium;chloride Chemical compound [Cl-].CC(=O)O[C@H](CC(O)=O)C[N+](C)(C)C JATPLOXBFFRHDN-DDWIOCJRSA-N 0.000 description 1
- 238000004026 adhesive bonding Methods 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229920000136 polysorbate Polymers 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H9/00—Networks comprising electromechanical or electro-acoustic devices; Electromechanical resonators
- H03H9/46—Filters
- H03H9/48—Coupling means therefor
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T29/00—Metal working
- Y10T29/49—Method of mechanical manufacture
- Y10T29/49002—Electrical device making
- Y10T29/49005—Acoustic transducer
Definitions
- the magnetic member is supported on a leaf spring [52] U.S. Cl. 333/71, 333/30 R for movement in a plane parallel to the surface of a [51] Int. Cl. H03h 9/04, H03h 9/26 ferromagneti member.
- Each coil member comprises [58] Field of Search 333/71, 30 R; 310/25 a flat coil m u d n a ferromagnetic m h coil having straight conductor segments extending at a [56] References Cited right angle to the relative motion.
- the other resonator is also provided with a coil and a permanent magnet core to convert mechanical motion of the second resonator into an electrical output signal.
- the resonator is moved toward the coil and back therefrom, so that a relatively large air gap is required to prevent touching of the resonator at the coil.
- U.S. Pat. No. 3,480,809 shows a prior art filter of this type.
- the filter cannot be adjusted by means of electric terminating resistances to the desired pass curve. As a result thereof only relatively small bandwidths are possible because each resonator generates for itself a pass curve. If an attempt is made to increase the bandwidth, an undesired ripple occurs in the middle of the pass region.
- a filter of relatively small bandwidth or with a relative large ripple in the pass region is not suitable for certain applications, for instance as the band-pass filter in a central remote control system, where low frequency signals are transmitted over the power mains.
- the low coupling factor of the transducer of the prior art filter has an effect such that the damping curve does not ascendto an infinite value at low frequencies, but attains a fixed value for the frequency zero, i.e., for DC current.
- the prior art filter is therefore not capable of blocking low frequencies, which again makes this filter unsuitable for certain applications.
- each resonator comprises a leaf spring to which a permanent magnet system forming the magnet member of the transducer is attached
- the coil member of the transducer comprises a flat coil lying in a plane arranged practically parallel to the oscillation plane of the resonator
- the permanent magnet system comprises a permanent magnet of high coercitive material located above the conductors of each half of the flat coil, both magnets being connected together by a yoke of ferromagnetic material and arranged in such a way that the free ends of the permanent magnets are of opposite polarities, and that the direction of magnetization of the permanent magnets extends parallel to the plane of the leaf spring and vertically to the plane of the coil, and that a ferromagnetic part is provided underneath the flat coil to complete the magnetic circuit of the permanent magnet system.
- the air gap between permanent magnet system and flat coil of each transducer can be kept very small.
- the magnetic circuit of the transducer carries from one permanent magnet over a short yoke to the other permanent magnet and from there over the air gap containing the windings of one half of the flat coil to the ferromagnetic part and from there again over the air gap with the windings of the other half of the coil back to the first mentioned permanent magnet.
- This advantageous design of the magnetic circuit has only small losses and permits, in combination with permanent magnets of high coercitive material, preferably a samarium cobalt alloy, the production of a very strong magnetic field in the air gaps.
- the permanent magnets magnetized vertically to the plane of the coil are not located adjacent to each other over a single half of the coil, as is frequently the arrangement on tuning fork oscillators where magnetic coupling is of secondary importance. Since the permanent magnets are located at a distance from each other, this prevents a large part of the magnetic flux from extending directly from a north pole to a south pole without vertically passing through the windings.
- the high electromagnetic coupling factor of the transducers of the inventive band-pass filter permits attainment of the desired relatively wide bandwidth.
- the use of high coercitive materials creates great difficulties or is impossible, because of the danger that the high attraction forces may cause the parts movable relative to each other to touch and block the resonator.
- the direction of magnetization parallel to the plane of the leaf spring has the advantage that the forces act edgewise on the leaf spring, so that it can hardly be deformed by th high coercitive forces. In this way, a constantly, equal air gap is assured.
- the ferromagnetic part carrying the flat coil extends on both sides further than the flat coil in the direction of the relative movement of the magnet system and the flat coil.
- the magnetic force lines of the permanent magnet system can enter practically vertically into the ferromagnetic part after having crossed the relatively small air gap containing the flat coil, and by the relative motion between the permanent magnet on one side of the flat coil with the ferromagnetic part on the other side, the magnetic force lines are moved vertically to their direction back and forth.
- the magnetic force lines also retain their original configuration during the movement because they are not deflected from their direction by the ferromagnetic part extending further than the coil. In this way, it is possible to obtain very high flux changes in the coil.
- the ferromagnetic part preferably comprises a material with small eddy current losses.
- the windings of the flat coil comprise straight conductor sections located substantially parallel to each other and approximately at a right angle to the relative motion, the straight conductor section representing the active part of the flat coil. This provides that in the operation of the transducer the magnetic field remains substantially limited to this active part. In this way, a good coupling factor of the transducer is assured.
- FIG. 1 is a top view of an electromechanical band filter comprising two electrodynamic transducers
- FIG. 2 shows a view of an electrodynamic transducer of an electromechanical band-pass filter
- FIG. 3 is a sectional view taken along the line II of FIG. 2;
- FIG. 4 is a perspective view of the basic parts of the electrodynamic transducer
- FIG. 5 shows a view of the transducer on which a leaf spring is used to mount the permanent magnet system at a small distance above the flat coil
- FIG. 6 is a side view of the transducer shown in FIG. 5.
- FIG. 1 shows a band-pass filter provided'with two electrodynamic transducers l and 1a.
- One transducer serves to convert electrical energy into mechanical motion of a first resonator, and the other transducer serves to convert mechanical motion into electrical energy.
- the mass of a permanent magnet system 2 serves together with the mass of a leaf spring 41 as oscillating mass, so that the unit comprising permanent magnet system 2 and the leaf spring 41 represents a mechanical resonator.
- the leaf springs 41 are connected to a support 43 which represents a mass coupling the resonators. Also mounted on the support 43 is part 5 (FIG. 3) with flat coils 3. The whole is suspended on supporting means (not shown) by suitable means such as thin rods 51, 53 and 55, for example. Other suspension means may be used provided that a high coupling factor can be obtained.
- the electrodynamic transducer basically comprises three parts, namely a permanent magnet system 2, a flat coil 3 and a ferromagnetic part 5.
- the flat coil 3 and the ferromagnetic part 5 form a mechanical unit.
- the permanent magnet system 2 is located above the flat coil 3 at a small distance in such a way that the permanent magnet system and the flat coil can move relative to each other.
- the flat coil 3 comprises a number of windings 7 which preferably comprise insulated copper wire.
- the design of the coil as a flat coil has the advantage that the air gap between the permanent magnet system 2 and the ferromagnetic part 5 can be kept small.
- a flat coil can also be safely fastened in a simple way on the ferromagnetic part 5. Fastening is preferably accomplished by glueing in such a way that the individual windings 7 of the flat coil.3 extend parallel to the surface 11 of the ferromagnetic part 5.
- the flat coil 3 has a form such that the windings 7 have straight conductor sections 9, as best shown in FIG. 4. In the embodiment shown, each winding has two straight conductor sections 9 lying in the flux region l3, 15 (FIG. 4) of the magnetic circuit 17 (FIG. 3). These straight conductor sections form the active part of the flat coil 3. The straight conductor sections are located at approximately a right angle to the relative motion.
- the permanent magnet system 2 preferably comprises a plate-like part or yoke 21 on one side of which two arms are provided at a distance from each other. These arms, 23 and 25, are preferably permanent magnets.
- the permanent magnets may, for example, comprise a samarium cobalt alloy, and are magnetized in such a way that one magnet has at its free end a magnetic north pole and the other magnet has at its free end a magnetic south pole. It would eventually also be possible to utilize a one piece permanent magnet system, if a magnetic path 17 is provided which is of such form that the magnetic flux lines extend approximately perpendicularly to the surface 11 of the ferromagnetic part.
- the permanent magnet system 2 is designed such that the magnetic field is substantially limited to the active part, that is to the straight conductor sections 9, of the flat coil 3. This provides that the magnetic flux lines intersect, on a relative motion of the permanent magnet system 2 and the flat coil 3, only the straight conductor sections 9 of the windings 7. This provides for a high coupling factor.
- Either the permanent magnet system 2 or the flat coil 3 may form the movable part. It would also be possible to move both parts. However, it is necessary for the mutual influence that there by relative motion between permanent magnet system 2 and flat coil 3. This can be a back and forward movement. It is important that the air gap 29 remains constant during relative motion be tween permanent magnet system 2 and flat coil 3, and this is the case when the permanent magnet system 2 is moved parallel to the surface 11 of the ferromagnetic part 5. To provide a forward and backward movement parallel to the surface of the ferromagnetic part 5 a leaf spring 41 (FIG. 5) can be provided, which is arranged in such a way that its flexing axis is perpendicular to the surface 11 of the ferromagnetic part 5.
- the permanent magnet system can only move parallel to the surface 11 of the ferromagnetic part 5.
- the ferromagnetiepart 5 together with the flat coil, is supported on a support 43 comprising an arm 45.
- One end of the leaf spring 41 is mounted on the arm 45, whereas the other end of the leaf spring 41 carries the permanent magnet system 2.
- the permanent magnet system can be moved parallel to the surface 11 of the ferromagnetic part, whereas a movement in the direction of the coil is impossible, because in this direction the leaf spring is stiff. Therefore, the permanent magnet system 2 cannot be drawn into contact with the flat coil by the acting magnetic forces.
- the electrodynamic transducer shown is admirably suitable for use in a resonator system of the type required in electromechanical filters.
- an induced voltage is generated at the terminals of the flat coil 3 according to the law of induction.
- This voltage U (FIG. 4) is proportional to the relative velocity V, and the number of conductors N and the length Iof the conductors in the field.
- a current I is applied to the flat coil 3 and a force K acts on the straight conductor sections 9 in the flux regions 13 and 15 of the magnetic field lines B of this field.
- the force K is determined by the following formula:
- the described electrodynamic transducer is, because of its small size and its high ratio of magnetic field energy to magnetic mass, particularly well suited for band-pass filters requiring a relatively large bandwidth.
- An electromechanical band-pass filter having transducers for converting electrical energy into mechanical motion of a resonator, and for converting mechanical motion of a resonator into electrical energy, each transducer comprising a magnet member and a coil member movable relative to each other, characterized in that:
- each resonator comprises a leaf spring to which a permanent magnet system forming the magnet member of the transducer is attached;
- the coil member of the transducer comprises a flat coil lying in a plane parallel to the oscillation plane of the resonator;
- the permanent magnet system comprises a permanent magnet of high coercitive material located above the conductors of each half of the flat coil;
- both magnets are connected together by a yoke of ferromagnetic material and arranged in such a way that the free ends of the permanentmagnets are of opposite polarities;
- the direction of magnetization of the permanent magnets extends parallel to the plane of the leaf spring and vertically to the plane of the coil;
Landscapes
- Physics & Mathematics (AREA)
- Acoustics & Sound (AREA)
- Piezo-Electric Or Mechanical Vibrators, Or Delay Or Filter Circuits (AREA)
- Control Of Motors That Do Not Use Commutators (AREA)
- Electromagnets (AREA)
- Coils Or Transformers For Communication (AREA)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CH868472A CH566091A5 (ja) | 1972-06-12 | 1972-06-12 | |
CH868572A CH571291A5 (ja) | 1972-06-12 | 1972-06-12 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3803521A true US3803521A (en) | 1974-04-09 |
Family
ID=25703622
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US366589A Expired - Lifetime US3914719A (en) | 1972-06-12 | 1973-06-04 | Band-pass filter and method of making same |
US00366590A Expired - Lifetime US3803521A (en) | 1972-06-12 | 1973-06-04 | Electromechanical band-pass filter |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US366589A Expired - Lifetime US3914719A (en) | 1972-06-12 | 1973-06-04 | Band-pass filter and method of making same |
Country Status (7)
Country | Link |
---|---|
US (2) | US3914719A (ja) |
JP (1) | JPS5652492B2 (ja) |
CH (2) | CH566091A5 (ja) |
DE (2) | DE2330288C3 (ja) |
FR (1) | FR2188362B1 (ja) |
GB (1) | GB1427537A (ja) |
NL (1) | NL7308120A (ja) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US20030030998A1 (en) * | 2001-07-02 | 2003-02-13 | Memscap | Microelectromechanical component |
US6549099B2 (en) | 2001-06-29 | 2003-04-15 | Hewlett-Packard Company | Electrically-coupled mechanical band-pass filter |
US7010978B1 (en) * | 1999-06-08 | 2006-03-14 | Optiscan Pty Ltd. | Electrically operated tuning fork |
Families Citing this family (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100473524B1 (ko) * | 2002-03-21 | 2005-03-09 | 한국과학기술원 | 비선형 기계적 변조기 및 이를 이용한 구동장치 |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3485035A (en) * | 1965-06-08 | 1969-12-23 | Messrs Gebruder Junghans Gmbh | Tuning fork devices |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
NL76872C (ja) * | 1948-11-11 | |||
JPS4527260Y1 (ja) * | 1966-12-13 | 1970-10-21 | ||
FR1571910A (ja) * | 1967-07-05 | 1969-06-20 | ||
GB1229871A (ja) * | 1967-08-24 | 1971-04-28 | ||
JPS4415741Y1 (ja) * | 1968-03-18 | 1969-07-07 | ||
US3621467A (en) * | 1969-04-10 | 1971-11-16 | Bulova Watch Co Inc | Amplitude limiter for tuning fork oscillator |
US3759133A (en) * | 1972-01-24 | 1973-09-18 | Bunker Ramo | Vibrator structure and method and apparatus for adjusting the frequency thereof |
-
1972
- 1972-06-12 CH CH868472A patent/CH566091A5/xx not_active IP Right Cessation
- 1972-06-12 CH CH868572A patent/CH571291A5/xx not_active IP Right Cessation
-
1973
- 1973-06-04 US US366589A patent/US3914719A/en not_active Expired - Lifetime
- 1973-06-04 US US00366590A patent/US3803521A/en not_active Expired - Lifetime
- 1973-06-08 GB GB2734673A patent/GB1427537A/en not_active Expired
- 1973-06-11 JP JP6576473A patent/JPS5652492B2/ja not_active Expired
- 1973-06-12 DE DE2330288A patent/DE2330288C3/de not_active Expired
- 1973-06-12 FR FR7321228A patent/FR2188362B1/fr not_active Expired
- 1973-06-12 DE DE2330287A patent/DE2330287A1/de active Pending
- 1973-06-12 NL NL7308120A patent/NL7308120A/xx unknown
Patent Citations (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3485035A (en) * | 1965-06-08 | 1969-12-23 | Messrs Gebruder Junghans Gmbh | Tuning fork devices |
US3529414A (en) * | 1965-06-08 | 1970-09-22 | Wolfgang Ganter | Tuning fork device |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7010978B1 (en) * | 1999-06-08 | 2006-03-14 | Optiscan Pty Ltd. | Electrically operated tuning fork |
US6549099B2 (en) | 2001-06-29 | 2003-04-15 | Hewlett-Packard Company | Electrically-coupled mechanical band-pass filter |
US20030030998A1 (en) * | 2001-07-02 | 2003-02-13 | Memscap | Microelectromechanical component |
Also Published As
Publication number | Publication date |
---|---|
FR2188362B1 (ja) | 1976-11-12 |
DE2330288C3 (de) | 1979-04-05 |
JPS5652492B2 (ja) | 1981-12-12 |
CH571291A5 (ja) | 1975-12-31 |
DE2330288A1 (de) | 1974-01-03 |
NL7308120A (ja) | 1973-12-14 |
USB366589I5 (ja) | 1975-01-28 |
US3914719A (en) | 1975-10-21 |
GB1427537A (en) | 1976-03-10 |
JPS4963361A (ja) | 1974-06-19 |
FR2188362A1 (ja) | 1974-01-18 |
DE2330288B2 (de) | 1978-08-03 |
DE2330287A1 (de) | 1974-01-03 |
CH566091A5 (ja) | 1975-08-29 |
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