US2646610A - Method of polarizing ceramic transducers - Google Patents

Method of polarizing ceramic transducers Download PDF

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Publication number
US2646610A
US2646610A US223389A US22338951A US2646610A US 2646610 A US2646610 A US 2646610A US 223389 A US223389 A US 223389A US 22338951 A US22338951 A US 22338951A US 2646610 A US2646610 A US 2646610A
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United States
Prior art keywords
points
polarizing
voltage
polarization
unidirectional
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Expired - Lifetime
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US223389A
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English (en)
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Alfred L W Williams
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Brush Development Co
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Brush Development Co
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Priority to NL86434D priority Critical patent/NL86434C/xx
Priority to BE510981D priority patent/BE510981A/xx
Application filed by Brush Development Co filed Critical Brush Development Co
Priority to US223389A priority patent/US2646610A/en
Priority to GB24228/51A priority patent/GB688179A/en
Priority to FR1058988D priority patent/FR1058988A/fr
Priority to DEN5425A priority patent/DE1000621B/de
Priority to CH300405D priority patent/CH300405A/de
Application granted granted Critical
Publication of US2646610A publication Critical patent/US2646610A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G7/00—Capacitors in which the capacitance is varied by non-mechanical means; Processes of their manufacture
    • H01G7/02—Electrets, i.e. having a permanently-polarised dielectric
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H3/00—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators
    • H03H3/007—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks
    • H03H3/02—Apparatus or processes specially adapted for the manufacture of impedance networks, resonating circuits, resonators for the manufacture of electromechanical resonators or networks for the manufacture of piezoelectric or electrostrictive resonators or networks
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N30/00—Piezoelectric or electrostrictive devices
    • H10N30/01—Manufacture or treatment
    • H10N30/04—Treatments to modify a piezoelectric or electrostrictive property, e.g. polarisation characteristics, vibration characteristics or mode tuning
    • H10N30/045—Treatments to modify a piezoelectric or electrostrictive property, e.g. polarisation characteristics, vibration characteristics or mode tuning by polarising
    • 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
    • Y10T29/42—Piezoelectric device making

Definitions

  • This invention relates generally to a method of polarizing a ceramic transducer and relates specifically to a method which is of particular utility in cases where it is difficult or impossible to polarize the ceramic material by the usual method of applying a voltage between two electrodes on opposite faces of the ceramic material.
  • ceramic electromechanical transducers have come into an extensive amount of use. Such transducers are generally comprised of a fired ceramic material which is comprised mainly of barium titanate, although in some cases the material may have added thereto a few Weight percent of some metal oxide in order to provide some particular operating character- 'sound' energy into a liquid medium, devices for producing mechanical energy from sound energy in a liquid medium, etc.
  • Several such transducers are described and claimed in United States Letters Patent No. 2,486,560 granted on Novemher 1, 1949, on an application of Robert B. Gray. filed on September 20, 1946.
  • transducers of the type here under consideration have found some use in devices where a continuous unidirectional bias voltage is applied while the transducers are in operation, it is the general practice to cause the material of such transducers to have a remanent polarization which renders the provision of the continuous unidirectional bias voltage during the operation'of the device unnecessary.
  • Materials of the type here under consideration are caused to have a remanent polarization by subjecting the mate- 'rial to the action of a high-intensity electric field at some time during the manufacturing process of the device. This polarizing of the material is usually done after the material has been fired and after suitable electrodes have been applied to the surfaces of the material. However, the voltages which are required for polarizing devices in this manner are sometimes very high.
  • a given voltage gradient across a thick piece of barium titanate transducer material is much more likely to ionize the surrounding air and cause a voltage breakdown across the surface of the material being polarized than is the same voltage gradient in the case where a very thin piece of ceramic material is being polarized in air.
  • the method of polarizing in a predetermined direction a fired ceramic transducer material which is capable of retaining a remanent polarization after having had a unidirectional voltage applied thereto comprises, applying a unidirectional polarizing voltage between a first two points spaced in the above-mentioned direction on a surface of the material for an appreciable period of time and of sufiicient magnitude as to eifect a polarization in the material between the two points.
  • the method also comprises the step of subsequently applying a unidirectional polarizing voltage between a second two points on the surface of the material which are spaced from the first two points in the above-mentioned direction with oneof the second two points being between the first two points and the other of the second two points being spaced from said first two points in the above-mentioned predetermined direction.
  • the method of polarizing in a predetermined direction a fired ceramic transducer material which is capable of retaining a remanent polarization after having had a unidirectional voltage applied thereto comprises, applying a unidirectional polarizing voltage between a first two points spaced in the direction of desired polarization on a surface of the material for an appreciable period of time and of suflicient magnitude as to effect a polarization in the materialbetween these two points.
  • This method also includes the subsequent step of effectively moving, in the desired direction of polarization on the surface of the material, the points of application of the polarizing voltage which is applied to the material.
  • Fig. 1 of the drawings is used to illustrate a preferred method of the invention as utilized to polarize a relatively thin plate of ceramic transducer material in the length direction of the material;
  • Fig. 2 is used to illustrate a modification of the Fig. 1 embodiment;
  • Fig. 3 is used to illustrate the method generally disclosed by the Fig. 2 arrangement as applied to a cylindrical ceramic transducer body; while
  • Fig. 4 is used to illustrate a modification of the Fig. 3 embodiment which is particularly useful in efiectuating a polarization in bodies which are relatively thick in a direction normal to the direction of desired polarization.
  • a plate [0 of ceramic transducer material which is to be polarized in the length direction.
  • Two conductive bars II and I2 are provided so that a polarizing voltage may be provided between them and so that the two bars may be moved as a unit in the length direction along the surface of the plate H).
  • two insulating spacers l4 and [5 are provided, these being fixedly secured to the bars.
  • fastening members IS and 2B which also serve as electrical terminals for applying a voltage between the rods I l and I2, are effective to fasten the insulating spacer to the rods H and 12, respectively.
  • a suitable source of polarizing voltage is applied to the conductive members [9 and from a source of D. C. voltage, indicated by the reference numeral 22.
  • the entire structure including the bars 1 i and i2 is slowly moved in the length direction of the material.
  • the degree of remanent polarization which is present in such a ceramic material is a function of the voltage as well as of the time the voltage is applied.
  • the structure including bars H and i2 can be moved lengthwise along the plate ['0 at such aratethat each part of the material is subjected to such a voltage gradient for this period of time.
  • the structure including bars I i and H can be moved at a faster rate and the operation can be repeated by bodily moving the structure back to the starting point but out of contact with the ceramic material to be polarized after the end of the material has been reached.
  • Various mechanical arrangements for eff'ectuating this type of action will be readily apparent to those skilled in the art.
  • a step-by-step movement can be utilized.
  • the structure can be left in the position shown for an appreciable period of time and thereafter can be moved bodily to a position further along the material in the length direction.
  • these steps should, in general, be no longer than the spacing between the bars It and i2 and, for most polarizing operations, the continuous movement described above is preferable.
  • either of the methods described abve comprises a method of polarizing the plate l0 in a predetermined direction, specifically in the length direction.
  • either of the described methods includes the step of applying a unidirectional polarizing voltage between a first two points, say between points 2 and 25, on a surface of the material for an: appreciable period of time and of sufiicient magnitude as to effect a polarization in the material between these two points.
  • the polarization here contemplated need not be the entire polarization ultimately effected in the material inassuch as the process may be repeated one or more times as mentioned above to increase the degree of polarization.
  • Either or the two methods described above also comprises the step of subsequently applying a unidirectional polarizing voltage between a second two points, for example, points 25 and 21 on the surface. of the material.
  • the points 2 6 and 21 are spaced from the points 24, 25 in the desired direction of polarization in the material, namely, in the length direction 01' the plate Ill. Also, one of the seci g and two points 26 and Z1 is between the first two points 24 and 25 and the other of the second two points, namely point 211, is spaced from the first two points 24 and 25 in thedesired direction of polarization, namely in the length direction. Also, either method described above, specifically the continuousv movement of the structure including bars H and I!
  • the method includes the step of applying a polarizing voltage to an incremental length of one surface of this material and includes the further step of subsequently moving the points of application of the voltage on this surface in the direction of this incremental length.
  • Fig. 2 the embodiment of the invention there illustrated is generally similar to that of Fig. 1 and corresponding elements have identical reference numerals.
  • the Fig. 2 embodiment differs from that of Fig. 1 only in that the bars [I and II are not directly moved over the surface of the ceramic transducer material during the polarizing operation.
  • conductive bristles or flexible strips 30, 30 are provided. These are attached to the bars H and I2 and effectively provide brushes which make a more intimate contact with the ceramic material under some circumstances than do the bars H and I2 of the Fig. l embodiment.
  • Fig. 3 for the purpose of illustrating a modification of the Fig. 2 arrangement.
  • the method of the invention is illustrated as being used for polarizing a ceramic transducer material in the form of a hollow right circular cylinder 3
  • Elements of Fig. 3 which are generally similar to those of Fig. 2 have identical reference numerals.
  • the operation of the Fig. 3 embodimen t will be readily understood from the-previous description.
  • a polarizing voltage from the source 22 is applied to the ceramic material 3
  • This rela tive motion may be effected by the movement of the entire structure including the bars II and 12' or may be eiiected by a rotation of the cylinder 3
  • the field pattern the cylinder is generally as represented by the dotted lines and is primarily in a circumferential direction in the material.
  • the relative motion can be either so slow that the entire desired polarization is effected during one; rotation of the cylinder 31, or the cylinder 3
  • Fig. 4 for illustrating a modification of the Fig. 3 embodiment wherein a second set of brush electrodes is provided the olinder.
  • Elements of Fig. 4 which are identical to those of Fig. 3 have identical reference numerals. Elements which are similar have identical reference numerals primed.
  • the brushstructure utilized inside the tube 3! of Fig. 4 includes conductive bars II and I2 having conductive bristles 3d, 36'. Only the insulating spacer member i5 is visible in the showing of Fig. 4, but it will be understood that the structure of the inside brush-electrode device is generally similar to that of the outside brush-electrode device. Furthermore, it will be seen that the inside brushes which directly oppose those on the outside have the same potential applied thereto so that there is no electric field directly through the material of the cylinder 3! in the radial direction thereof.
  • Fig. 4 The operation of the Fig. 4 embodiment will be readily understood by those skilled in the art from the previous descriptions of operation.
  • the field pattern in the ceramic material is somewhat as illustrated by the dotted lines 36 and it will readily be seen that this field pattern is preferable to that illustrated by the numeral 34 of Fig. 3 where a thick material is to be polarized.
  • the cylinder of Fig. 4 has been utilized in describing the operation of the double-brush arrangement simply for purposes of illustration and that a double-polarizing structure may be utilized in any of the other embodiments as well.
  • this double-brush structure provides an arrangement in which a unidirectional polarizing voltage is applied between a first two points spaced in a given direction on a surface of the material, for example, between two points on the outside surface of the cylinder of Fig. 4.
  • a corresponding unidirectional polarizing voltage between a first two points on the other of the surfaces of the cylinder, namely, on the inside surface of the cylinder of Fig. 4, the voltages applied inside and out being corresponding ones in that they produce a field in the same direction in the material.
  • the two points of voltage application on the inside surface oppose the two points of voltage application on the outside surface.
  • a unidirectional polarizing voltage between another two points on the one surface mentioned above, specifically the outside surface in the illustration of Fig. 4.
  • These other two points are spaced from the first two points on the outside surface in the direction of desired polarization with one of these other two points being between the first two points, namely the firstmentioned two points on the outside surface of the surface of the cylinder, and the other of the two points on the outside surface being circumferentially spaced from the first two points on the outside surface under consideration in the predetermined direction of polarization.
  • any of the embodiments of the invention mentioned above may be utilized in polarizing a ceramic transducer material at normal room temperatures, for example in air.
  • the polarizing voltage is then applied to the material and all portions of the ceramic transducer material which are desired to be polarized are treated while the ceramic is maintained at the temperature near the Curie point.
  • the temperature of the oil bath is next reduced by a small factor and the polarizing potentials are again applied in the same manner to all portions of the ceramic material desired to be polarized.
  • cylinders illustrated in Figs. 3 and 4 are specifically suitable for this arrangement in that they may be continuously rotated so that all portions of the ceramic material are subjected to the desired polarizing voltage before the temperature of the oil bath is materially reduced. Thereafter the temperature of the bath is further reduced and the process is continued until a temperature quite far removed from the Curie point of the material is reached.
  • the method of polarizing in a predetermined direction a fired ceramic transducer material which is capable of retaining a remanent polarization after having had a unidirectional voltage applied thereto comprising: applying a unidirectional polarizing voltage between a first two points, spaced in said direction on a surface of said material, for an appreciable period of time and of sufficient magnitude as to effect a polarization in said material between said two points; and subsequently applying a unidirectional polarizing voltage between a second two points on said surface spaced from said first two points in said direction, with one of said second two points being between said first two points, and the other of said second two points being spaced from said first two points in said predetermined direction.
  • the method of polarizing in a predetermined direction a fired ceramic transducer material which is capable of retaining a remanent polarization after having had a unidirectional voltage applied thereto comprising: applying a unidirectional polarizing voltage between a first two points, spaced in said direction on a surface of said material, for an appreciable period of time and of sufficient magnitude as to effect a polarization in said material between said two points; and subsequently effectively moving in said direction on said surface the points of application of said voltage to said material.
  • the method of polarizing in a predetermined direction a fired ceramic transducer material which is capable of retaining a remanent polarization after having had a unidirectional voltage applied theret comprising: applying a unidirectional polarizing voltage between a first two points, spaced in said direction on a surface of said material, for an appreciable period of time and of sufiicient magnitude as to effect a polarization in said material between said two points; and subsequently moving in said direction on said surface the points of application of said voltage to said material to provide a succession of succeeding pairs of points of voltage application to said material such that one point of a particular pair is always between the points of the preceding pair, while the other of the points of said particular pair is always spaced from the point of the preceding pair in said predetermined direction.
  • the method of polarizing a fired ceramic transducer material which has one relatively small dimension between two surfaces of said material, in a direction which is substantially normal to said dimension, the material being one which is capable of retaining a remanent polarization after having had a unidirectional voltage applied thereto comprising: applying a unidirectional polarizing voltage between a first two points, spaced in said direction on a surface of said material, for an appreciable period of time and of suflicient magnitude as to effect a polarization in said material between said two points; and subsequently applying a unidirectional polarizing voltage between a second two points on said surface spaced from said first two points in said direction, one of said second two points being between said first two points, and the other of said second two points being spaced from said first two points in said predetermined direction.
  • the method of polarizing a fired ceramic transducer material which has one relatively small dimension between two surfaces of said material, in a direction which is substantially normal to said dimension and the material being one which is capable of retaining a remanent polarization after having had a unidirectional voltage applied thereto comprising: applying a unidirectional polarizing voltage between a first two points, spaced in said direction on one of said surfaces of said material, for an appreciable period of time and of sufficient magnitude as to effect a polarization in said material between said two points; simultaneously applying a corresponding unidirectional polarizing voltage between a first two points on the other of said surfaces which oppose the said first two points on said one surface; subsequently applying a unidirectional polarizing voltage between another two points on said one surface which are spaced from said first two points in said direction with one of said other two points being between said first two points on said one surface and the other of said other two points being spaced from said first two points on said one surface in said predetermined direction; and, simultaneously with said subsequent application of
  • the method of polarizing a fired ceramic transducer material which has a relatively short dimension and a relatively long dimension substantially normal thereto and which material is capable of retaining a remanent polarization after having had a unidirectional voltage applied thereto which comprises: applying a unidirectional polarizing voltage between two lines on a surface or said material, each of which is substantially normal to said two dimensions, the lines being spaced in said longitudinal direction on said surface and the voltage being applied for a period of time and of sufficient magnitude as to effect a polarization in said material between said two lines; and subsequently simultaneously moving the lines of application of said potential to said surface in said longitudinal direction.
  • the method of polarizing in a predetermined direction a fired ceramic transducer material, in a form having two relatively closely spaced surfaces which are substantially equidistant at all corresponding points thereof, and which is capable of retaining a remanent polarization after having had a unidirectional voltage applied thereto comprising: applying a polarizing voltage to an incremental length of a surface of said material; and subsequently moving the points of application of said voltage on said surface in the direction of said incremental length.
  • the method of polarizing in a predetermined direction a fired ceramic transducer material, of a form having two relatively closely spaced surfaces which are substantially equidistant at all corresponding points thereof, and which material is capable of retaining a remanent polarization after having had a unidirectional voltage applied thereto comprising: applying a polarizing voltage to an incremental length of one of said surfaces; applying simultaneously a corresponding polarizing voltage to a corresponding incremental length of the other of said surfaces; subsequentl moving the points of application of said voltage on said one surface in the direction of said incremental length; and, simultaneously with the moving of the points of application of said voltage on said one surface, moving the points of application of said voltage on said other surface correspondingly in the direction of said incremental length.
  • the method of polarizing in a circumferential direction a hollow cylinder of fired ceramic transducer material which is capable of retaining a remanent polarization after having had a unidirectional voltage applied thereto comprising: applying a unidirectional polarizing voltage between two points on a surface of said cylinder, which are spaced in a circumferential direction on said surface, for an appreciable period of time and of sufficient magnitude as toeffect a polarization in said material between said two points; and subsequently simultaneously moving the points of application of said voltage along the surface of said cylinder in a circumferential direction to effect a polarization in other circumferential portions of said cylinder.

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Compositions Of Oxide Ceramics (AREA)
  • General Electrical Machinery Utilizing Piezoelectricity, Electrostriction Or Magnetostriction (AREA)
US223389A 1951-04-27 1951-04-27 Method of polarizing ceramic transducers Expired - Lifetime US2646610A (en)

Priority Applications (7)

Application Number Priority Date Filing Date Title
NL86434D NL86434C (US07122603-20061017-C00294.png) 1951-04-27
BE510981D BE510981A (US07122603-20061017-C00294.png) 1951-04-27
US223389A US2646610A (en) 1951-04-27 1951-04-27 Method of polarizing ceramic transducers
GB24228/51A GB688179A (en) 1951-04-27 1951-10-17 Method of polarizing a ceramic transducer
FR1058988D FR1058988A (fr) 1951-04-27 1952-04-01 Procédé de polarisation d'un transducteur en matière céramique
DEN5425A DE1000621B (de) 1951-04-27 1952-04-23 Verfahren zum Polarisieren eines Koerpers aus keramischem piezoelektrischem Material
CH300405D CH300405A (de) 1951-04-27 1952-04-25 Verfahren zum Polarisieren eines Körpers aus keramischem piezoelektrischem Material.

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US223389A US2646610A (en) 1951-04-27 1951-04-27 Method of polarizing ceramic transducers

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US2646610A true US2646610A (en) 1953-07-28

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US223389A Expired - Lifetime US2646610A (en) 1951-04-27 1951-04-27 Method of polarizing ceramic transducers

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US (1) US2646610A (US07122603-20061017-C00294.png)
BE (1) BE510981A (US07122603-20061017-C00294.png)
CH (1) CH300405A (US07122603-20061017-C00294.png)
DE (1) DE1000621B (US07122603-20061017-C00294.png)
FR (1) FR1058988A (US07122603-20061017-C00294.png)
GB (1) GB688179A (US07122603-20061017-C00294.png)
NL (1) NL86434C (US07122603-20061017-C00294.png)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3071841A (en) * 1957-02-16 1963-01-08 Philips Corp Method of longitudinally pre-polarizing bodies consisting of at least one layer of piezoelectric material
US3193912A (en) * 1963-01-04 1965-07-13 Lab De Rech S Physiques Electro-static particle collecting device
US4734611A (en) * 1985-12-20 1988-03-29 Siemens Aktiengesellschaft Ultrasonic sensor
US5668439A (en) * 1995-10-03 1997-09-16 Xerox Corporation High voltage power supply

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2521329A (en) * 1947-08-15 1950-09-05 Brush Dev Co Repolarized transducer system
US2532100A (en) * 1947-05-29 1950-11-28 Indiana Steel Products Co Electromagnetic transducer head
US2540412A (en) * 1947-12-26 1951-02-06 Zenith Radio Corp Piezoelectric transducer and method for producing same

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2532100A (en) * 1947-05-29 1950-11-28 Indiana Steel Products Co Electromagnetic transducer head
US2521329A (en) * 1947-08-15 1950-09-05 Brush Dev Co Repolarized transducer system
US2540412A (en) * 1947-12-26 1951-02-06 Zenith Radio Corp Piezoelectric transducer and method for producing same
US2540194A (en) * 1947-12-26 1951-02-06 Zenith Radio Corp Piezoelectric transducer and method for producing same

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3071841A (en) * 1957-02-16 1963-01-08 Philips Corp Method of longitudinally pre-polarizing bodies consisting of at least one layer of piezoelectric material
US3193912A (en) * 1963-01-04 1965-07-13 Lab De Rech S Physiques Electro-static particle collecting device
US4734611A (en) * 1985-12-20 1988-03-29 Siemens Aktiengesellschaft Ultrasonic sensor
US5668439A (en) * 1995-10-03 1997-09-16 Xerox Corporation High voltage power supply

Also Published As

Publication number Publication date
CH300405A (de) 1954-07-31
GB688179A (en) 1953-02-25
FR1058988A (fr) 1954-03-22
NL86434C (US07122603-20061017-C00294.png)
DE1000621B (de) 1957-01-10
BE510981A (US07122603-20061017-C00294.png)

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