US3488565A - Ultra-flat variable capacitor assembly - Google Patents

Description

jan., 6, 1970 E. s. TELTscHE-R ULTRA-FLAT VARIABLE CAPACITOR ASSEMBLY 3 Sheets-Sheet 1 '25 2 seb was FRG. 4 54 68 7 Fi? ed Feb.

2 515 //e4/54 ee INVENTOR: ERwfN S. TELTSCHER f5 f5 w@ BY. ATTORNEY.

ULTRA-FLAT VARIABLE CAPACITOR ASSEMBLY Filed Fe'v. 7, 1968 3 Sheets-Sheet l United States Patent O 3,488 565 ULTRA-FLAT VARIABLE CAPACITOR ASSEMBLY Erwin S. Teltscher, 69 Dianas Trail, Roslyn, N.Y. 11576 Filed Feb. 7, 1968, Ser. No. 703,611 Int. Cl. H01g 5/01, 5/00, 1/00 U.S. Cl. 317-255 Claims ABSTRACT 0F THE DISCLOSURE The invention relates generally to the art of variable capacitors and more particularly concerns an ultra-flat variable capacitor assembly which may be used as a tunable component of a miniature radio.

It has been proposed heretofore to provide a miniature radio in a wristwatch and wrist band such as de scribed in U.S. -Patent No. 3,032,651. Parts of the radio are included in the casing which contains the watch movement. This arrangement has not proven commercially feasible because a standard watch m-ovement cannot be used. A specially designed and fabricated watch movement must be provided which is prohibitively expensive. Also parts of the radio are too small and crowded in the watch case to operate efficiently. Installation of the many radio componentsI in the watch case requires expensive precision hand work which is undesirable; also servicing of both the watch movement and the radio is very difficult, complicated and expensive.

The present invention avoids the above and other difficulties by providing an ultra-flat capacitor assembly which can be installed in a support for a watch movement or mounted in a Wrist band to serve as a tuning component for a miniature radio installed in the wrist band. The capacitances of the capacitor assembly are variable. The variable capacitor assembly has general utility and is capable of use in a great variety of applications; however, its particular stucture adapts it especially for use as a tuning component of a miniature radio forming part of a wristwatch or wrist band.

To obtain high capacitance in a capacitor having a very small volume, it is necessary to use a material of high dielectric constant between conductive plates of the capacitor. Ceramic materials having a dielectric constant as high as 10,000 are known. While it is known to manufacture fixed capacitors with such materials, it is very difficult to use these materials in manufacturing variable capacitors because surfaces of both the capacitor plates and the ceramic material of high dielectric constant must be subjected to high precision grinding and polishing. This is necessary in order to insure smooth Contact between the relatively movable capacitor plates and ceramic dielectric slabs therebetween.

In the present invention, ceramic slabs having high dielectric constant are used, but precision machining of lboth the capacitor plates and ceramic slabs is avoided. This is done in one version of the invention by employing as conductive capacitor plates metallic liquid capacitor electrodes arranged as pistons which slide smoothly in surface contact with fixed dielectric slabs. The liquid capacitor plates or electrodes are pistons of mercury having sealing members at opposite ends disposed movably in passages provided in the 4capacitor assembly. The passages are rectangular or round in cross section. A man- Patented Jan. 6, 1970 ually operated knob drives a gear mechanism coupled directly or magnetically to the pistons to move them in the passages.

In another version of the invention, the conductive capacitor plates are fixed in position at sides of chambers containing a liquid dielectric such as distilled Water. Dielectric slabs having a high dielectric constant are movably disposed in the chambers between the capacitor plates. The dielectric slabs are movable magnetically by a manually operable control. In a modification of the invention, the dielectric slabs are movable by a gear mechanism directly coupled to the slabs. The liquid di electric in the chambers has a high dielectric constant of about 60 and provides liquid contact between the ceramic dielectric slabs and the adjacent conductive capacitor so that precision grinding and finishing of adjacent surfaces of the slabs and plates is unnecessary.

The invention will be explained in further detail in connection with the drawings, wherein:

FIG. l is a perspective view of a wrist watch in which is installed a miniature radio and including an ultra-flat radio tuning capacitor assembly mounted in a support for the watch movement.

FIG. 2 is a fragmentary perspective View of the 'watch support of FIG. 1 with the ultra-flat variable capacit-or assembly shown mounted thereon.

FIG. 3 is a reduced bottom plan view of the watch support and variable capacitor assembly of FIG. 2.

FIG. 4 is an enlarge-d vertical cross sectional view taken on line 4 4 of FIG. 2.

FIG. 5 is a horizontal cross sectional view taken on line S-S of FIG. 4.

FIG. 6 is a perspective view of another wrist watch, with the variable capacitor assembly shown mounted on a wrist band.

FIG. 7 and FIG 8 are sectional views similar to FIG 5, showing the features of construction of two other variable capacitors according to the invention.

FIG. 9 is a cross sectional view taken on line 9 9 of FIG. 8.

FIGS. 10 and 14 are sectional views similar to FIG 5, showing two other ultra-fiat variable capacitor assemblies.

FIG. 1l is a cross sectional view taken on line 11-11 of FIG. 10Y

FIG. 12 is a fragmentary vertical sectional View taken on line 12--12, but enlarged in the vertical direction.

FIG. 13 is a fragmentary vertical side elevational view englarged in the vertical direction, taken on line 1313 of FIG l0.

Referring first to FIG. 1, there is shown a wristwatch 10 including a frame-like casing 12 having a Wrist strap or band with two hollow band sections 14 and 16 pivotally connected to casing 12. A watch movement 11 is mounted on the outer side or top of casing 12. Inside band section 14 are components of a radio receiver including a miniature loudspeaker 18, transistors 20, antenna 21 and other components 22. In band section 16 are batteries 24 and an on-off switch and volume 26. To the extent described, the components of the radio receiver and their disposition in the Wrist band, and their interconnections are largely conventional.

Now according to the invention, a variable capacitor assembly 25 for tuning the radio receiver is mounted under the watch movement 11 on base plate or wall 30 of the casing 12; see FIGS. 2 and 3. The ultra-flat variable capacitor assembly is best shown in FIGS. 4 and 5 to which reference is now made. The variable capacitor has a knurled circular knob 32 which is diametrically longer than the width of casing 12 so that diametrically opposite portions of the knob are exposed for manual turning. The knob is secured to rotatable central post or stub shaft 34 engaged in a circular insulator plate 36 made of insulative material such as a suitable phenolic or other type plastic. Plate 36 is secured by screws 38 to the base plate 30 as shown in FIG. 3. Secured to but spaced from plate 36 by four bolts 37 held by nuts 39 is another 'circular insulator plate 40 which underlays knob 32 and serves as a gurde and support therefor. Plates 36 and 40 are stationary while knob 32 is rotatable with respect to the plates. A tuning scale 42 can be marked on the periphery of the knob 32 to cooperate with xed index mark 44 on the periphery of plate 36; see FIG. 2.

Two rectangular passages 50a and 50h are defined between plates 36 and 40. Each passage has a side wall formed of a ceramic slab 52 made of a material having a high dielectric constant as much as 10,000. Parallel to slabs 52 are metal side bars 54. The ceramic slabs 52 and bars 54 are set into grooves 55, 56 in plates 36 and 40. Capacitor plates or electrodes in the form of metallic liquid pistons 58a and 58h are movably disposed inside the passages 50a, 5011 defined by slabs 52, bars 54 and plates 36, 40. Cylindrical sealing heads 60, 62 are provided at opposite ends of the liquid pistons. Both the liquid pistons and the sealing heads are magnetic so that they can be moved by bar magnets 64, 66 disposed adjacent to bars 54. The magnetic liquid pistons can be composed of mercury loaded with small magnetic particles such as described in U.S. Patent No. 3,344,3 73. Attached to magnets 64, 66 are elongated frame-like rack gears 68 whose opposed teeth 70 are engaged on opposite sides of pinion 72. The pinion is mounted on stub shaft 34 and rotates with shaft 34 when knob 32 is turned. By the arrangement described, when the knob is turned, one assembly of rack gear and magnet will move in one direction almost diametrically of plates 36, 40 while the other rack gear and magnet will move in opposite direction. The liquid pistons and magnetic heads will move with their associated magnets in opposite directions.

On the outer sides of bars 54 are lixed capacitor plates 74, 76 formed by thin metallic coatings or layers located at opposite end portions of the respective bars. Connected to plates 74 and 76 by soldering or otherwise are stationary electric contact lugs 78, 79 to which components of the radio receiver shown in FIG. l are connected via suitably arranged lead wires. Another electric contact lug 80 is connected to both bars 54 to serve as a common ground terminal. The lug 80 is set in a groove 80a in plate 36. By the arrangement described the assembly actually includes two separate variable capacitors. Each capacitor has a ceramic dielectric slab S2. A metal layer 74 or 76 constitutes one electrode or plate of the capacitor, and a liquid metal piston 58a or 58h constitutes the other electrodes or plate of the capacitor. Since each piston is movable with respect to fixed capacitor layer 74 or 76, the capacitances of the two capacitors are variable simultaneously. The capacitors may have different capacitances if the pistons are of different length and/or if the layers 74, 76 are of different length, and/ or if the distances separating the dielectric slabs 52 and bars 54 are dilferent.

The capacitor assembly described can be made in a size which is large enough for use as a tuning capacitor for a radio and yet small enough for installation in a wrist watch. As a practical example, the variable capacitor assembly 25 can be about an inch in diameter and about an eighth of an inch in thickness. This miniature assembly is rendered practical, economical to manufacture and operative by the provision of the liquid pistons which require no precision machining of the adjacent ceramic slabs to insure perfect sealing contact thereto while sliding along the slabs.

FIG. 6 shows a wrist watch 10A which has a hollow wrist band in which components of a radio receiver are installed. The variable capacitor assembly is installed in the wrist band itself. Opposite ends of the wrist band are attached to casing 12 containing watch movement 11. Both the casing and watch moVGmGIl tre of conventional construction. Other parts corresponding to those of wrist watch 10 in FIG. 1 are identically numbered. The construction shown in FIG. 6 may be preferred since there is more room available for manipulating the knob 32, and because a conventional watch casing can then be used. The construction of Wrist watch 10 of FIG. 1, may be preferred however if a more compact assembly is desired.

In FIG. 7 is shown another capacitor assembly 25a which is generally similar to capacitor assembly 2S and corresponding parts are identically numbered. In assembly 25a, arm 81 at one end of each frame-like gear 68a terminates in a shaft 89 attached to one of the piston heads 62a. A shaft 82 is attached to the other piston head 60a. This shaft extends into a cup 8S formed at one end of arm 86 of the rack gears and bears against a coil spring 88 in the cup. By this arrangement, when the body of mercury in each of passages 50a, 501) expands and contracts due to temperature changes, the springs 88 correspondingly contract and expand. The magnets 64 and 66 of assembly 25 are omitted so that the mercury pistons 58a and 5811 and piston heads 60a, 62a need not be magnetic. These piston heads can be made of rubber or other resilient material to seal the mercury in passages 50a, 5017.

In FIGS. 8 and 9 is shown another ultra-fiat capacitor assembly 25h which is similar to both assemblies 2S and 25a and corresponding parts are identically numbered. In assembly 25b, the ceramic dielectric slabs 52 are cylindrical in form and are seated in recesses 51, 53 in plates 36', 40'. The cylindrical slabs define cylindrical passages 50a' and 50b in which the metallic liquid pistons 58a and 58b are movably disposed. The piston heads 60', 60" and 62', 62 are cylindrical in form to conform with the interior passages of the cylindrical slabs. These piston heads may be made of rubber. Shafts 90 and 92 are connected by nuts 87, 87 between piston heads 60, 62 and arms 81', 86" of the rack gears 68b and 68b. Cups 8S and 85 are provided at ends of arms 86 and 81 of the rack gears. Coil springs 88 and 88' are disposed in these cups and shafts 82', 82 extend between piston heads 60 and 62". Capacitor plates 74', 76 are thin metal layers of silver or other metal which are cylindrical since they surround the cylindrical slabs 52 at opposite end portions thereof. Pinion gear 72' is engaged with rack gear 68 while pinion gear 72 which is larger in diameter pinion 72 is engaged with rack gear 68b. Fixed electrical lugs 78', 79 terminates in adjustable clamps 96 frictionally engaged with shafts 82', 82" to permit the shafts to slide axially while remaining in direct electric circuit with the lugs. The shafts 82', 82 and 90, 92 all contact the pistons 58a and 58h at opposite ends thereof to provide electrical continuity between the pistons and contact lugs 78',` 79. Lug 80 is set in groove a in plate 36 and serves as a ground contact or terminal of the assembly. Lug 80 is connected to both capacitor plates 74 and 76'. Plates 36 and 40 are held together by screws 37 and cylindrical washers 37". By the arrangement described, the pistons 58a', 58b' will be moved at different speeds with respect to their associated xed capacitor plates 74', 76 when knob 32 is turned. Thus the capacitances of the two capacitors included in the assembly will vary at different relative rates even though cylinders 52, 52' are identical in size.

It will be noted that in all capacitor assemblies, there are two capacitor components simultaneously controlled by turning knob 32. Each capacitor component is defined by a ceramic dielectric slab which is flat or cylindrical, with a metallic liquid piston movably disposed at one side of the slab to serve as one capacitor plate or electrode, and with a metallized layer fixed on the other side of the ceramic slab to serve as the other capacitor plate or electrode. Mechanical means are provided between the pistons and knob so that turning the knob effects movements of the pistons in both capacitor coniponents simultaneously. The capacitor assemblies can be manufactured at relatively low cost because precision maching of the ceramic slabs is avoided. The liquid pistons conform precisely Iand perfectly with the surfaces of the slabs as they slide along the slabs. The ultra-fiat configuration of the capacitor assemblies makes them especially adaptable for use in wrist carried radio receivers, but they can be employed in other applications where small, thin, fiat, variable capacitors are required.

In FIGS. -13 is shown a ganged ultra-fiat capacitor assembly 25C in which parts corresponding to those of assemblies 25, 25a and 25h are identically numbered. Assembly 25e` has a flat rotatable knob 32 on shaft 34 which rotates pinion 72a. Pinion 72a engages two straight rack gears 68C which move in opposite directions. Two flat rectangular thin-walled liquid- tight casings 100, 102 made of insulation material are supported on flat insulator plate 103 by end spacers 101. Each casing is filled with distilled water 105 liquid dielectric 105 such as distilled water. Extending longitudinally of each casing are side walls 107 and spaced interior partitions 109. Set in these Walls and partitions are conductive plates 104, 106 alternating with each other. Alternate plates are connected to contact leads 108 and 110. The walls and partitions of the casings define compartments 111. Ceramic slabs 112 made of material having a dielectric constant as high as 10,000 are disposed slidably in the chambers 111. The slabs move freely between plates 104, 106 from which the slabs are spaced. Each slab 112 is joined at one end to a slab 113 made of a material having a dielectric constant of approximately unity of 1.0 Magnets or magnetic elements 114, 116 are secured to opposite ends of the joined slabs 112, 113. The assemblies of slabs 112, 113 and magnets or magnetic elements 114, 116 are surrounded by liquid dielectric 10S which fills each compartment 111 as shown clearly in FIGS. 10, 11 and 12.

Attached to opposite ends of the rack gears 68e are bar magnets 118, 120 which surround casings 100, 102. The rack gears may form parts of the magnetic circuit. Magnets 118, 120 magnetically engage the magnets or magnetic elements 114, 116 to cause the dielectric slabs 112, 113 to move in opposite directions in casings 100 and 102 when knob 32 is turned in one direction or the other.

FIG. 14 shows Ianother ganged capacitor assembly 25d which is generally similar to assemblies 25, 25a, 25b and 25e and corresponding parts are identically numbered. In assembly 25d, direct drive of the ceramic dielectric slabs 112, 113 is effected in both casings simultaneously by multiple fingers 150, 152 joined to opposite ends of the slabs and extending through end Walls 154 of casings 100', 102. Fingers 150, 152 extend slidably through rubber sealing gaskets 156 which seal the distilled water 105 in compartments 111 Fingers 150, 152 are joined to arms 158 connected to opposite ends of the rack gears 68d engaged with pinion gear 72a. The magnets 114, 116, 118 'and 120 of assembly 25C are omitted to provide direct drive of the ceramic slabs in opposite directions by the rack gears 68d when knob 32 is turned. Casings 100 and 102' are secured to supporting plates 36" and 40 at opposite sides in a manner similar to the arrangement of these plates in assemblies 25, 25a and ZSb.

The basic principle underlying the construction and operation of the ultra-flat capacitor assemblies 25C and 25d is the alternate insertion and withdrawal of slabs of material having high dielectric constant Within spaces between pairs of metal plates 104, 106. The material of high dielectric constant is surrounded by a liquid dielectric 105 which may be distilled water having a dielectric constant of about 60.0. By this liquid means, perfect contact between the conducting surfaces of the metal plates and the ceramic slabs is effected. Since the contact is via a liquid medium, high precision machining of the sides of the slabs and plates is not required.

Any desired number of capacitor plates 104, 106 and movable slabs 112, 113 can be provided to obtain any desired capacitances of the variable capacitor assembly. Such ganged multiple plate variable capacitors have well recognized utility in tuning superheterodyne radio receivers and other applications.

Although distilled water is mentioned it will be understood that other electrically nonconductive liquids having dielectric properties can be used. Other modifications of the invention may be made without departing from the invention as defined in the appended claims.

What is claimed is:

1. An ultraflat variable capacitor assembly, comprising a plurality of spaced stationary conductive and nonconductive members with a plurality of passages therebetween constituting a plurality of capacitors; a plurality of bodies movable along said passages respectively and beyond at least one of the conductive members of each capacitor thereat to vary electrical capacitances of said capacitors, said bodies being magnetic at least in part; and driving means comprising magnet means disposed externally of said passages and attracting magnetic parts of said bodies to move said bodies in said passages.

2. An ultraflat variable capacitor assembly as defined in claim 1, further comprising control means engaging the driving means to move the same, so that the bodies move simultaneously in the passages to vary the electrical capacitances of the capacitors simultaneously.

3. An ultraflat variable capacitor assembly as defined by claim 1, wherein said bodies are composed at least in part of dielectric material to vary the dielectric constants of the capacitors when the bodies move in the passages.

4. An ultrafiat variable capacitor assembly as defined by claim 1, wherein said passages are filled with a dielectric fluid surrounding said bodies to insure perfect contact between said bodies and said conductive members via said fluid.

5. An ultraflat Variable ca-pacitor assembly as defined by claim 4, wherein said members define hermetically sealed closed chambers containing said passages to seal said fluid in said passages.

6. An ultraflat variable capacitor assembly as defined by claim 1, wherein said bodies have the form of at slabs narrower in width than said passages to define spaces between the slabs and adjacent sides of said members, said assembly further comprising dielectric liquid surrounding said bodies to insure perfect contact between said bodies and said conductive members via said liquid, said members defining hermetically sealed closed chambers to seal said liquid in said passages.

7. An ultraflat variable capacitor assembly comprising a plurality of laterally spaced, stationary, parallel, fiat, narrow conductive and nonconductive members defining walls of a plurality of straight passages spaced laterally apart and constituting a plurality of capacitors; a plurality of bodies movable axially along said passages respectively parallel to said conductive members to vary electrical capacitances of the capacitors; driving means disposed externally of said passages operatively arranged to move said bodies in said passages; and control means engaging the driving means to move the same, so that the bodies moves in the passages to vary the electrical capacitances of the capacitors simultaneously.

8. An ultraflat variable capacitor assembly as defined by claim 7, wherein said bodies are magnetic at least in part, said driving means comprising magnet means attracting said bodies to move the same magnetically in said passages. i f We?! 9. An ultrafiat capacitor assembly as defined by claim 7, wherein said bodies have the form of fiat slabs narrower in width than said passages to define spaces between the slabs and adjacent sides of said members, said assembly further comprising dielectric liquid surrounding said bodies to insure perfect contact between said bodies and said conductive members via said liquid.

' 7 8 10. An ultraat variable capacitor assembly as defined 2,589,134 3/ 1952 Pyle 317-251 X by claim 9, wherein said members are arranged to-dene 2,881,372 4/ 1959 Dublier 317-249 hermetlcally sealed closed chambers contammg said pas- FOREIGN PATENTS sages to seal the liquid in said passages.

133,991 6/1949 Australla.

References Cited 5 E A GOLDBERG P E UNITED STATES PATENTS mary Kammer 1,548,801 8/1925 Jacobs 317-251 U.S. Cl. X.R. 1,667,058 4/1928 Smith 317-251 317 249J 251y 253 1,820,357 8/1931 Lindstrom 317-249 X 10

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