US3551872A - Thin film adjustable attenuator with s-shaped bifurcated contacts - Google Patents

Thin film adjustable attenuator with s-shaped bifurcated contacts Download PDF

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Publication number
US3551872A
US3551872A US785715A US3551872DA US3551872A US 3551872 A US3551872 A US 3551872A US 785715 A US785715 A US 785715A US 3551872D A US3551872D A US 3551872DA US 3551872 A US3551872 A US 3551872A
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United States
Prior art keywords
thin film
terminals
contacts
resistive
attenuator
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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
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US785715A
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English (en)
Inventor
John T Emmott
Nathan G Lesh
Mead F Stevens
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AT&T Corp
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Bell Telephone Laboratories Inc
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Publication date
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C10/00—Adjustable resistors
    • H01C10/06—Adjustable resistors adjustable by short-circuiting different amounts of the resistive element
    • H01C10/08—Adjustable resistors adjustable by short-circuiting different amounts of the resistive element with intervening conducting structure between the resistive element and the short-circuiting means, e.g. taps
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01C—RESISTORS
    • H01C10/00—Adjustable resistors
    • H01C10/30—Adjustable resistors the contact sliding along resistive element
    • H01C10/38—Adjustable resistors the contact sliding along resistive element the contact moving along a straight path
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/24—Frequency- independent attenuators

Definitions

  • An adjustable attentuator is provided by an integral unit which includes a thin film substrate with a preselected pattern of area resistors deposited thereon. Dual spring contacts, arranged for sliding movement across areas of the film, selectively bridge different portions of the resistive pattern to provide incremental adjustments in the attenuation level.
  • Kinkels device utilizes a flat nonconductive base or substrate with a plurality of discrete resistive film areas deposited thereon. A plurality of contacts are contiguous with and located along each side of each of the resistive film areas. An insulating cover member with printed circuit paths on the inside surface thereof is fitted over the base portion to form the completed component.
  • the base includes three conductive land areas deposited at one end portion thereof with a terminal extending outwardly from each of the land areas. Corresponding land areas on the inside of the cover are placed to ensure registry with the land areas on the substrate.
  • contact buttons on the inside cover are placed to ensure registry with the contacts on the substrate.
  • a desired length of film can be employed to provide a preselected resistance.
  • the cover as initially formed, includes sufiicient circuit paths to interconnect with the paths on the base in several different patterns, each resulting in a different resistance. The unwanted paths are then removed from the cover selectively in accordance with the particular resistance pattern desired. Changing the resistance of the attenuator thus requires changing the resistive pattern on the cover or, alternatively, a plurality of covers may be employed for a single base and a resistance change may be effected by changing the cover.
  • an object of the invention is to simplify the adjustability aspect of adjustable thin film attenuators. Another object is to simplfy the overall construction of thin film attenuators and thereby reduce the cost thereof.
  • an adjustable attenuator employing a pattern of thin film area resistors and connecting conductive areas deposited on a common substrate in combination with spring loaded contacts which are slidably adjustable across the surface of the thin film deposits.
  • the configuration of the contacts permits selective bridging of discrete areas of the thin film and the level of attenuation is thus readily attained by the simple movement of a sliding switch.
  • the high degree of miniaturization achieved by unique layer and surface pattern configurations of area resistors allows a plurality of attenuation adjustments to be derived from a single substrate base in combination with a like plurality of sliding switches.
  • a complete multiple adjustment attenuator arrangement is packaged in an assembly measuring approximately 1 /2 X 1" x A".
  • Each of four conveniently positioned slide switches on one surface of the assembly may be moved from a neutral to a full throw position to introduce progressively greater magnitudes of attenuation.
  • the opposite side of the assembly casing includes an integral terminal mounting arrangement and each of the terminals is mounted over a corresponding aperture in the casing to facilitate lead connections from related thin film areas.
  • the thin film resistive elements of the attenuator are combined into several balanced H pads deposited on a common substrate.
  • the element values are adjusted, as by anodizing for example, to meet the combined performance parameters of insertion loss and impedance rather than absolute resistance.
  • maximum yield is realized during production which obtains from the fact that insertion loss is virtually independent of impedance, i.e., the geometry determines the insertion loss and hence the resistance ratio exclusive of impedance.
  • Impedance is dependent only on the resistivity and has relatively broad tolerances of two to three percent, for example, while the tolerance of insertion loss may be as close as 0.1 percent. Accordingly, when anodizing, it is possible to accept the relatively broad limits of plus or minus three percent on resistivity by selectively anodizing to the required voltage ratio.
  • the switch contacts perform their function by sliding across the surface of the thin film substrate and the termination area of the thin film circuit is utilized as one contact of each slide switch. It is this feature which contributes to the overall compactness and simplicity of an attenuator in accordance with the invention.
  • FIG. 1 is a perspective view of an assembled multiadjustment attentuator in according with the invention
  • FIG. 2 is an exploded view drawn to an enlarged scale of the attenuator shown in FIG. 1;
  • FIG. 3 is a partially exploded view of the underside of the attenuator shown in FIG. 2;
  • FIG. 4 is a perspective view of the thin film circuit shown in FIG. 2 drawn to a distorted scale to illustrate the layer configuration
  • FIG. 5 is a plan view drawn to an enlarged scale of the thin film circuit shown in FIG. 2.
  • the switch housing includes a lower housing member or base 201 interfitted with an upper housing member or cover 205.
  • the thin film resistive circuit 202 rests within the frame formed by the base 201.
  • Apertures 208 in the base 201 are provided to accommodate terminating leads, not shown, which are aflixed to the terminals 501 through 504 on the thin film circuit shown in FIG. 5. These leads are threaded through the apertures 208, also shown in FIG. 3, and through the corresponding apertures 302 of the connecting pins 301 and are suitably affixed thereto as by soldering, for example.
  • Each of the connecting pins 301 includes a respective one of the output terminals 207.
  • Each of four slide bars 203 is housed for sliding movement within the cover 205 and is in alignment with a respective one of the slots 209.
  • Each of the bars 203 includes a raised aperture or shoulder portion 212 which accommodates a respective one of the downwardly projecting studs 210 of a corresponding one of the thumb buttons 206.
  • each of eight spring contactors 204 is affixed to and is supported by a respective end portion of one of the slide bars 203. As shown, each of the spring contactors 204 is placed so that the dual contact elements 211 extend downwardly to permit engaging relation with the surface of the thin film element 202.
  • the cover 205 may advantageously be joined to the base 201 and the buttons 206 may be afiixed to the slide bars 203 by means of ultrasonic bonding.
  • This is wellknown technique is simple and effective and is readily adapted to mass production procedures. Heat treating after bonding is desirable to stress relieve the molded plastic piece parts which may advantageously be formed from Lexan, a commercially available polycarbonate.
  • FIG. 3 shows that the underside of the base 201 is provided with a series of bosses or raised areas 303 which include slots 304 for accommodating or positioning the shank portion of each of the terminal pins 301, so that the apertures 302 are in correspondence with the apertures 208 and so that the connecting terminals 207 are positioned in the manner shown in FIG. 1.
  • a terminal indicating plate 305 which is bonded to the tops of the bosses 303 secures the terminals 301 in place.
  • FIG. 5 One illustrative configuration for the thin film circuitry which incorporates the resistive H pads is shown in detail plan view in FIG. 5, and a portion thereof is shown in FIG. 4 to illustrate typical layer compositions and layer thicknesses.
  • the small rectangles 50A, B through 61A, B on the thin film surface mark slightly raised land areas that are in conductive relation with the contacts 211 of the spring contactors 204. As shown in FIG. 4 these areas are formed from layers of gold, platinum or rhodium and gold. Any one of a number of materials such as glass, glass wth an oxide underlay, glazed alumina or superfine alumina may be used to form the substrate for the thin film circuits.
  • a better appreciation of the fact that the resistive thin film patterns shown on FIG. 5 are the equivalents of conventional lumped element resistive H pads may be gained by examining the correspondence between the terminals of an equivalent lumped element H pad and the area type terminals of one of the FIG. 5 deposited H pads.
  • a conventional H pad has four external terminals corresponding to the two termination points on each of the two exterior leg or verticals.
  • resistors there is a pair of resistors in each of the two legs, the external terminals of the pad corresponding to the unconnected terminals of these resistors and the common terminals of the resistors forming the internal terminals of the cross bar or horizontal member which normally includes still another resistor.
  • terminals A and 60B When the slide is pushed to the position of attenuation, however, one set of contacts connects terminals A and 60B, and the other set of contacts is shifted to a neutral position across the terminals 54A and 54B. This position is termed neutral in view of the fact that these terminals are contiguously conductive and no change in the circuit is introduced by bridging across such terminals.
  • the terminals 60A and 60B correspond to a pair of terminals which require connection in order to complete a circuit path across the cross bar or horizontal member of the H pad. Without the area terminals 60A and 60B connected, there is an open in the circuit which of course corresponds to the noattenuation position.
  • Attenuators in accordance with the invention may be employed to particular advantage in various communication equipment where the maintenance of precise levels of attenuation are critical to effective operation.
  • Such equipment may, for example, include inband signaling units and high frequency repeater units.
  • two attenuators of the type disclosed herein, each employing four slide bar units are utilized to cover a 16.5 db range of attenuation.
  • the units differ only in the substrate pattern, although color coding may advantageously be employed to ensure proper identification.
  • the two substrate patterns provide loss increments of 0.1, 0.2, 0.4, 0.8 and 1, 2, 4, 8 db respectively at constant impedance.
  • Each of the eight two-position slide switches can be moved manually from a zero loss position to one of the abovelisted increments.
  • An adjustable attenuator comprising, in combination, a plurality of thin film resistive elements deposited on a common substrate, a base member including support means for said substrate, a cover member positioned over said base member thereby to form an attenuator housing, a plurality of contact carrying slide members each in combination with a manually movable button member aligned with a corresponding cover slot thereby to permit slidably adjusting the position of said slide members with respect to said thin film resistive elements, first and second S-shaped spring contact members mounted on each of said slide members, the top portion of each of said S-shaped contact members being spring fitted around a corresponding end of an associated one of said slide members, the bottom portion of each of said S-shaped contact members depending downwardly to and in predetermined contact with selected ones of said resistive elements, each of said bottom portions including bifurcated contacts whereby the movement of a single one of said slide members may be utilized to bridge two pairs of terminal points on said thin film resistive elements.
  • resistive elements are formed into a plurality of H pads each corresponding to an associated one of said contact carrying slide members, each pair of said bifurcated contacts on one pair of said spring contact members being employed to short circuit a corresponding one of the outer legs on one of said H pads with the associated one of said slide members being in a first or no-attenuation position and one of said last named pairs of contacts completing the circuit for the internal cross leg of said last named H pad and the other of said last named pairs of contacts being placed in a neutral position whenever said last named slide member is in a second or full-attenuation position.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Adjustable Resistors (AREA)
  • Slide Switches (AREA)
US785715A 1968-12-20 1968-12-20 Thin film adjustable attenuator with s-shaped bifurcated contacts Expired - Lifetime US3551872A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US78571568A 1968-12-20 1968-12-20

Publications (1)

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US3551872A true US3551872A (en) 1970-12-29

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Application Number Title Priority Date Filing Date
US785715A Expired - Lifetime US3551872A (en) 1968-12-20 1968-12-20 Thin film adjustable attenuator with s-shaped bifurcated contacts

Country Status (7)

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US (1) US3551872A (enrdf_load_stackoverflow)
JP (1) JPS4813785B1 (enrdf_load_stackoverflow)
BE (1) BE743203A (enrdf_load_stackoverflow)
DE (1) DE1962951A1 (enrdf_load_stackoverflow)
FR (1) FR2026680A1 (enrdf_load_stackoverflow)
GB (1) GB1290355A (enrdf_load_stackoverflow)
NL (1) NL6918768A (enrdf_load_stackoverflow)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3769480A (en) * 1972-06-15 1973-10-30 Eaton Corp Hoist electric control handle with first operating means, including a movable s-shaped resistor, and second operating means
US3784948A (en) * 1971-12-23 1974-01-08 Bunker Ramo Integrated circuit package of unified structure with variable resistor
US3837067A (en) * 1971-12-23 1974-09-24 Bunker Ramo Method of making integrated circuit package
USRE28565E (en) * 1971-07-29 1975-09-30 Adjustable active equalizer
US4734672A (en) * 1985-09-25 1988-03-29 Alps Electric Co., Ltd. Variable resistor circuit module and method of manufacture

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6241325U (enrdf_load_stackoverflow) * 1985-08-31 1987-03-12
JPH0340826U (enrdf_load_stackoverflow) * 1989-08-30 1991-04-19

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
USRE28565E (en) * 1971-07-29 1975-09-30 Adjustable active equalizer
US3784948A (en) * 1971-12-23 1974-01-08 Bunker Ramo Integrated circuit package of unified structure with variable resistor
US3837067A (en) * 1971-12-23 1974-09-24 Bunker Ramo Method of making integrated circuit package
US3769480A (en) * 1972-06-15 1973-10-30 Eaton Corp Hoist electric control handle with first operating means, including a movable s-shaped resistor, and second operating means
US4734672A (en) * 1985-09-25 1988-03-29 Alps Electric Co., Ltd. Variable resistor circuit module and method of manufacture

Also Published As

Publication number Publication date
NL6918768A (enrdf_load_stackoverflow) 1970-06-23
FR2026680A1 (enrdf_load_stackoverflow) 1970-09-18
JPS4813785B1 (enrdf_load_stackoverflow) 1973-04-28
DE1962951A1 (de) 1970-07-02
GB1290355A (enrdf_load_stackoverflow) 1972-09-27
BE743203A (enrdf_load_stackoverflow) 1970-05-28

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