US3214525A

US3214525A - Stereophonic piezoelectric bender-type transducer

Info

Publication number: US3214525A
Application number: US848116A
Authority: US
Inventors: Eyck Robert R Ten
Original assignee: Gulton Industries Inc
Current assignee: Gulton Industries Inc
Priority date: 1959-10-22
Filing date: 1959-10-22
Publication date: 1965-10-26
Anticipated expiration: 1982-10-26

Description

Oct. 26, 1965 R. R. TEN EYCK 3,2 4,

STEREOPHONIC PIEZOELECTRIC BENDER-TYPE TRANSDUCER Filed OCT,- 22, 1959 2 Sheets-Sheet l MN 54 I Tijll]. INVENTOR. TATE. Eoaem R TEN EYCK ATTORNEY Oct. 26, 1965 R. R. TEN EYCK 3,214,525

STEREOPHONIC PIEZOELECTRIC BENDER-TYPE TRANSDUCER Filed Oct. 22, 1959 2 Sheets-Sheet 2 152 756 f84 T5117. T3115. 1a?

IN V EN TOR.

204 TiclEEl ROBERT E TEN EYCK QTTOENEY United States Patent 3,214,525 STEREOPHONIC PIEZOELECTRIC BENDER-TYPE TRANSDUCER Robert R. Ten Eyck, Metucheu, N.J., assignor to Gulton Industries, Inc., Metuehen, N.J., a corporation of New Jersey Filed Oct. 22, 1959, Ser. No. 848,116 9 Claims. (Cl. 179-10041) My invention relates to stereophonic transducers and in particular to those stereophonic transducers which are formed of ferroelectric ceramic material.

An important object of my invention is to provide a stereophonic transducer with relatively high sensitivity and low cross coupling between the channels.

It is a further object of my invention to provide such a transducer which has low mass, high capacity and high compliance.

It is a still further object of my invention to provide such a transducer which is simple and economical to produce.

These and other objects, advantages and features of my invention will be apparent during the course of the following discussion when taken in conjunction with the accompanying drawings wherein:

FIGURE 1 is an elevational view, partly in cross-section, of one embodiment of my invention,

FIGURE 2 is an elevational view of the active ceramic element of FIGURE 1,

FIGURE 3 is a cross-sectional view along the line 3-3 of FIGURE 2,

FIGURE 4 is a view similar to FIGURE 1 of a further embodiment of my invention,

FIGURE 5 is a view similar to that of FIGURE 2 of the active ceramic element of FIGURE 4,

FIGURE 6 is a view along the line 66 of FIGURE 4 viewed in the direction of the arrows,

FIGURES 7, 9, 11, 13, 15, and 17 are views similar to that of FIGURE 2 showing various electrode arrangements and configurations of the active ceramic element used in the carrying out of the teachings of my invention,

FIGURES 8, 10, 12, 14, 16, and 18 are cross-sectional views taken, in the order listed, respectively as follows: along the line 88 of FIGURE 7; along the line Iii-1t of FIGURE 9; along the line 12-12 of FIGURE 11; along the line 1414 of FIGURE 13; along the line 16-16 of FIGURE along the line 18-48 of FIG- URE 17,

FIGURE 19 is an exploded perspective view showing still another embodiment of my invention,

FIGURE 20 is an assembled perspective view of the embodiment of FIGURE 19, and

FIGURE 21 is a schematic diagram showing the electrical connections made to the electrodes of the active elements illustrated in the various figures.

In the drawings, wherein, for the purpose of illustration, are shown various embodiments of my invention and wherein like numerals are used for like parts throughout the same, the numeral generally designates a stereophonic transducer of my invention. In FIGURE 1, transducer 40 is seen to comprise ferrolelectric ceramic element 42 which is in the form of a hollow cylinder provided with a longitudinal slit extending throughout the length thereof and to which have been applied outer electrodes 44 and 45 (only one of which is shown in FIGURE 2 as 44), metallic torsion bar 50, plastic cap 46 and case 48. Affixed to element 42 is cup 56 to which is afiixed stylus assembly 52.

Stylii

54 and 54a are affixed to assembly 52 and are provided to enable the user to flip the cartridge over when different stylus point radii are required depending on the record groove dimensions.

Electrode 47 on the inner surface of element 42 covers the complete surface so that in effect there are three electrodes on element 42; first, electrode 44 on the outer surface of element 42 as shown in FIGURE 2; second, electrode 45 similar in size and location to electrode 44 on the outer surface of element 42 opposite electrode 44; and third, electrode 47 on the inner surface of element 42. Connection is made to electrode 47 through torsion bar 50 as shown in FIGURE 1. If desired, two electrodes may be applied to theinner surface of element 42 so that pairs are formed with the outer electrodes.

I have found that sufficient separation between the channels is achieved when using stereophonic pickups made in accordance with my invention to produce excellent subjective results and statistical measurements comparable with the stereophonic pickups now in use and publicly accepted.

Electrical connections are made as shown in FIGURE 21. The output of the right channel amplifier is connected between the common connection and that marked RIGHT in the figure and the left channel amplifier is connected between the common connection and that marked LEFT in the figure. As can be seen in FIG- URE 21 the LEFT channel is connected to electrode 44, the RIGHT channel is connected to outer electrode 45 (not shown in FIGURE 21) and the common connection is made to inner electrode 47. The record groove in which stylus 54 rides is designated as 205.

Brass cup 56 of FIGURE 1 is used to couple the ceramic transducer element 42 to the stylus assembly 52. The inside diameter of cup 56 is such that element 42 is seated within cup 56 to provide just enough clearance to apply bonding cement such as a nitrocellulose base cement to the combination so that the active ceramic element is securely bonded to the cup. The bonding cement is such that there is good physical and mechanical bonding between the element and the cup and good acoustic transmission and coupling between the ceramic element and the stylus assembly. Nonelectroded margin 43 is provided to prevent the brass cup from shorting electrode 44 to electrode 45.

FIGURES 4, 5 and 6 illustrate a further embodiment of my invention which is very similar to the embodiment of FIGURES 1 through 3. The complete assembly, generally designated as 60, comprises a longitudinally split, hollow cylindrical ceramic element 62, case 68, plastic cap 66, metallic torsion bar 70 through which electrical connection is made to the inner electrode, metallic bar 76, and stylus assembly 52. Electrode 64 is applied to element 62 in any manner well-known in the art and the other electrodes needed to complete the device such as are shown in FIGURE 3 are not shown in this particular embodiment. It should be noted that the ceramic elements of FIGURES 2 and 5 are interchangeable and may be used in either embodiment.

Metallic bar 76 is used to provide the necessary stylus to ceramic coupling. In this embodiment, the bar is bonded to the inside of the tube and it is not necessary to provide insulation between the bar and the inner electrode because the inner electrode is at ground potential. While I chose to use metal as the material for bar 76 because of the ease of machining it, I have also found that a molded plastic such as polyethylene is desirable because of its lower density and consequent lower mass per volume.

The various electrode ceramic element configurations shown in FIGURES 7 through 18 may be used with either of the embodiments described above. The ceramic element of FIGURES 7 and 8 is designated 82 and it comprises a hollow cylinder provided with a lower longitudinal slit throughout the length thereof and an upper longitudinal slit which extends from the free end thereof for substantially the length thereof, and has inner electrode 87 and

outer electrodes

84 and 85 applied thereto. In FIGURES 9 and 10, the ceramic element is designated 102 and it corresponds in construction to ceramic element 82, and it has applied thereto

outer electrodes

104 and 105 and inner electrode 107. In FIGURES 11 and 12, the ceramic element is designated 122 and it corresponds in construction to ceramic element 82, and it has applied thereto

outer electrodes

124 and 125 and inner electrode 127. The ceramic element of FIGURES 13 and 14 is designated 142 and it comprises a hollow cylinder provided with upper and lower slits extending from the free end thereof for substantially the length thereof and has applied thereon

outer electrodes

144 and 145 and inner electrode 147. In FIGURES 1S and 16, the ceramic element is designated 162 and it corresponds in construction to ceramic element 142, and it has applied thereon

outer electrodes

164 and 165 and inner electrode 167. The ceramic element of FIGURES 17 and 18 is designated as 182 and it corresponds in construction to ceramic element 82, and it has applied thereon outer electrodes 184 and 185 and inner electrode 187.

In FIGURES 19 and 20 there is shown a further embodiment of my invention, generally designated as 200. It comprises hollow semicylindrical

ceramic elements

206 and 208 to each of which are applied inner electrode 210 and outer electrode 212, rubber grommet 204 and stylus assembly 202. Rubber grommet 204 is suitably bonded to stylus assembly 202 by means of nitrocellulose base cement and is then bonded to the inside of

elements

206 and 208 by means of nitrocellulose base cement.

Elements

206 and 208 are bonded to a torsion bar similar to

bars

50 and 70 by means of nitrocellulose base cement. The assembled

elements

206 and 208 provide a hollow cylinder provided with upper and lower slits extending throughout the length thereof.

In FIGURE 21 there is shown still another embodiment of my invention in which a different stylus assembly 203 is bonded to the longitudinally split, hollow cylindrical, ceramic element 42 by means of a nitrocellulose base cement.

The fiip over stylii, shown in the various figures, are provided to permit the reproduction of both monophonic and stereophonic recordings With the single assembly. In operation as a stereophonic reproducing transducer, the stylus transmits the channel motion of the usual 45 stereophonic record groove or channel to the ceramic element such that there is a mechanical stress produced in the respective channel volumes or portions of the ceramic element corresponding to the conformation of the original recording groove. As a result, the right portion of the element responds to signals from a right motion of the stylus and the left portion responds to signals from a left motion of the stylus. This is due to the fact that the ceramic element responds to the respective 45 motions of the record groove or channel.

Due to the asymetrical construction of a split cylinder the resultant strain due to the motion and stress applied thereto by the stylus is greater in one half the element and the other for the 45 directions of stress. This effect can be enhanced by electroding only in the region of maximum strain (near the top of the unit). Cross coupling through the unelectroded top region is only due to shear elasticity and not piezoelectric effects and is generally small in ceramic transducers.

The electroding of FIGURES and 16, and 17 and 18 gives the best sensitivity and channel separation. Quality of music reproduction is not lost with the other electroding configurations, and where a high capacity is needed, the larger electroded area would be necessary and channel separation could be improved by mechanical means.

While I have described my invention in terms of its use as a stereophonic phonograph pickup, devices of my invention may also be used as stereophonic record cutters since the device is a reversible transducer. For reproduction of monophonic recordings the stylii are flipped over to proivde the appropriate stylus for the groove or channel of the monophonic record and the electrodes of the ceramic element are switched to place them in the circuit of the amplifier to provide the monophonic reproduction.

I prefer to form the ceramic element for my invention of the ferroelectric ceramics such as barium titanate, lead titanate-zirconate or similar materials polarized to be piezoelectric, but the element may be formed of any other piezoelectric material having the same electromechanical properties as the foregoing materials.

While I have disclosed my invention in relation to specific examples and in specific embodiments, I do not wish to be limited thereto, for obvious modifications will occur to those skilled in the art without departing from the spirit and scope of my invention.

Having thus described my invention, I claim:

1. A stereophonic transducer comprising a hollow, cylindrical, ferroelectric ceramic body, means for mounting said body at one end only with the other end free to move laterally said body being provided with at least one 10ngitudinal slit running from one end thereof for substantially the length of said body, at least three electrodes affixed to said body, one of said electrodes being placed on the outer surface of said body on one side of said slit, the second of said electrodes being placed on the outer surface of said body on the second side of said slit, the third of said electrodes being placed on the inner surface of said body, a stylus atfixed to said body in alignment with the slit at the free end thereof for laterally bending the body to oppositely stress the body between the first and third electrodes and between the second and third electrodes, and means for making electrical connections to said electrodes.

2. A stereophonic transducer as described in claim 1 wherein said third electrode is applied to the inner surface of said body substantially opposite said first electrode and including a fourth electrode applied to the inner surface of said body substantially opposite said second electrode.

3. A stereophonic transducer comprising a hollow, cylindrical, ferroelectric ceramic body, means for mounting said body at one end thereof, said body being provided with a pair of oppositely placed, longitudinal slits running from the free end thereof for substantially the length of said body, two pairs of electrodes affixed to said body, one of said pairs of electrodes being placed between one side of said slits on the inner and outer surfaces of said body, the other of said pairs of electrodes being placed between the other side of said slits on the inner and outer surfaces of said body, a stylus afiixed to said body in alignment with the slits at the free end thereof, and means for making electrical connections to said pairs of electrodes.

4. A stereophonic transducer as described in claim 3 wherein each of said electrodes covers substantially all the surface to which it is affixed and which is between said pair of slits.

5. A stereophonic transducer as described in claim 3 wherein the electrodes applied to the outer surfaces of said body are spaced from the open end of said slits and olccupy substantially all of the circumference between said s its.

6. A stereophonic transducer as described in claim 5 wherein said electrodes occupy approximately one half of the circumference between said slits.

7. A stereophonic transducer for use with a 45 stereophonic record groove comprising a hollow, cylindrical, ferroelectric ceramic body, means for mounting said body at one end thereof, said body being provided with at least one longitudinal slit running from the free end thereof for substantially the length of said body, at least three electrodes aflixed to said body, one of said electrodes, being placed on the outer surface of said body on one side of said slit, the second of said electrodes being placed on the outer surface of said body on the second side of said slit, the third of said electrodes being placed on the inner surface of said body, a stylus aifixed to said body in alignment with the slit on the free end thereof and engageable in the 45 stereophonic record groove for stressing the portions of the ceramic body on opposite sides of the slit therein in accordance with the undulations on opposite sides of the 45 stereophonic record groove, and means for making electrical connections to said electrodes for transmitting electrical signals in accordance with the stressing of said portions of the ceramic body.

8. A stereophonic transducer as described in claim 7 wherein said third electrode is applied to the inner surface of said body substantially opposite said first electrode and including a fourth electrode applied to the inner surface of said body substantially opposite said second electrode.

9. A stereophonic transducer comprising a hollow, cylindrical, ferroelectric ceramic body, means for mounting said body at one end only with the other end free to move laterally, said body being provided With a longitudinal slit running from the free end thereof for substantially the length of said body, three electrodes afiixed to said body, the first of said electrodes being placed on the outer surface of said body on one side of said slit, the second of said electrodes being placed on the outer surface of said body on the other side of said slit, the third of said electrodes being placed on the inner surface of said body in radial alignment with both of said first and second electrodes, a stylus affixed to said body in alignment with the slit at the free end thereof for laterally bending the body to oppositely stress the body between the first and third electrodes and between the second and third electrodes, and means for making electrical connections to said electrodes.

References Cited by the Examiner UNITED STATES PATENTS 2,719,929 10/55 Brown 179100.4l 2,928,069 3/60 Petermann 179-100.41 2,944,117 7/60 Gray 179100.41

IRVING L. SRAGOW, Primary Examiner.

ROBERT H. ROSE, JOHN P. WILDMAN, Examiners.

Claims

1. A STEREOPHONIC TRANSDUCER COMPRISING A HOLLOW, CYLINDRICAL, FERROELECTRIC CERAMIC BODY, MEANS FOR MOUNTING SAID BODY AT ONE END ONLY WITH THE OTHER END FREE TO MOVE LATERALLY SAID BODY BEING PROVIDED WITH AT LEAST ONE LONGITUDINAL SLIT RUNNING FROM ONE END THEREOF FOR SUBSTANTIALLY THE LENGTH OF SAID BODY, AT LEAST THREE ELECTRODES AFFIXED TO SAID BODY, ONE OF SAID ELECTRODES BEING PLACED ON THE OUTER SURFACE OF SAID BODY ON ONE SIDE OF SAID SLIT, THE SECOND OF SAID ELECTRODES BEING PLACED ON THE OUTER SURFACE OF SAID BODY ON THE SECOND SIDE OF SAID SLIT, THE THIRD OF SAID ELECTRODES BEING PLACED ON THE INNER SURFACE OF SAID BODY, A STYLUS AFFIXED TO SAID BODY IN ALIGNMENT WITH THE SLIT AT THE FREE END THEREOF FOR LATERALLY BENDING THE BODY TO OPPOSITELY STRESS THE BODY BETWEEN THE FIRST AND THIRD ELECTRODES AND BETWEEN THE SECOND AND THIRD ELECTRODES, AND MEANS FOR MAKING ELECTRICAL CONNECTIONS TO SAID ELECTRODES.