US2438893A

US2438893A - Translating device

Info

Publication number: US2438893A
Application number: US516051A
Authority: US
Inventors: Carl A Bieling
Original assignee: Bell Telephone Laboratories Inc
Current assignee: AT&T Corp
Priority date: 1943-12-29
Filing date: 1943-12-29
Publication date: 1948-04-06
Anticipated expiration: 1965-04-06

Description

April 6, 1948.

C. A. BlELlNG TRANSLATING DEVICE Filed Dee. 29, 1943 Wwwgww? 2 Sheets-Sheet 2 n ATTORNEY Patented Apr. 6, 1948 TRANSLATING DEVICE carin. Bieling, Westfield, N. J., assigner to Ben Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York 4Application December 29, 1943, Serial No. 516,051

This invention relates to electrical translating E devices and particularly to those of th'e solid-contact type.

The objects of the invention are to increase the load capacity of electrical translators; to increase the life and useful service of these devices; to minimize the hazard of failure due to overload; to attain these ends with a simple and efficient structural design; to enable @wider choice in the selection of -rectifying material foruse in translating devices; and to realize other improvements and advantages.

The employment of ultra-high frequencies for signaling purposes in' the radio and allied arts has made it necessaryto devise special translatng devices for detecting, converting, and otherwise translating signal waves having frequencies of the order of a few centimeters. At theselextremely high frequencies the conventional elec'- tron tube devices are inadequate,` andattention has turned to rectiers and translators of the solid-contact type. A In one of 4its forms the solidcontact rectifier used at these ultra-high frequencies comprises a fine tungsten wire mounted in such` manner that itsv free end engages the surface of an element having suitable rectifying properties, such as a crystal of silicon.

One of the requirements imposed upon the reotier is that the area of contact between the end of the tungsten wire and the silicon surface shall be extremely small. The Idiameter of the wire,

for example, is only a few thousandths of an inch,

and the end of the wire is pointed to obtain a contact area at the crystalsurface which is even smaller. Because of the minute sizeof the contact area, the amount of electrical power which the unit can sustain is correspondingly limited. If excessive power is applied, the rectifying property of the unit is impaired or even destroyed. The deleterious change which the unit suffers when subjected to more power than it can safely `sustain is sometimes known as burn-out, which is a hazard imposing undesirable limitations upon the rectifier and the system in whichit is used.

A feature of the invention, therefore, is a translating unit in which these disadvanta-ges are overcome and in which the power sustaining capacity is greatly increased. More specifically the improved rectifying unit is a lstructure containing a plurality of solid-contact rectifying elements arranged in such manner as to divide the total load sustained by the unit.

ments are mounted in tandem within an insulate- 9 Claims. (Cl. Z50-31) ing housing and in which adjustable devices-are provided for obtaining the necessary contact pressure between the contact wires and the individual rectifying elements.

Another feature of the invention is a'rectifying structure in which the rectifying contact points are located closely together in the electrical circuit. The purpose of this feature is ytoobtain a better distribution of the applied voltage wave at centimeter wavelengths.

Another feature of the'inventlon is a rectifier structure which makes it possible to employ crystal rectifying elements having different electrical properties. Crystal elements of'silicon prepared in accordance ,with certain methods are found to have oppositeelectrical properties. In other words some of these elements are positive and others are negative, meaning that a rectifier having apositive element will conduct current from the crystal to the wire and that a rectifier having a negative element will conduct from the wire to the crystal. According to the present feature, therefore, the rectifier structure is so arranged that the current may iiow in a given direction through the unit although it comprises rectifying elements of opposite electrical properties.

Another feature which supplements and enhances the effectiveness of the foregoing features is an improved spring contact element. `More specifically this element is formed from a length of ne wire by grinding th'e end to a conical point, grinding or otherwise forming two sets of opposing iiat surfaces on the sides of the conical end to produce a small rectangular contact surface at the tip of the wire, rolling or otherwise .forming the intermediate section ofthe wire until it assumes the shape of a ribbon,` and bending the ribbon section to give it the desired resilence. With this construction the contactelement has a maximum spring compression fora given force, the distance between the contact tip and Ithe holder can be reduced to a minimum, and a maximum area of conductor surface is obtained from a wire of given diameter.

These and other features of the invention will be described more fully in the following detailed specification. Y

In the drawings accompanying the'specication,

Fig. 1 is an enlarged assembly view, partly in cross section, of a translating unit incorporating `the features of the invention;

Fig. 2 is a perspective view of th'e insulating cylinder which forms the housing of the rectitying elements;

`tying elements.

Fig. 3 is a detail view of the adjustable supporting member within the insulating cylinder;

Fig. 4 is a top view of this supporting member;

Fig. 5 is a mounting member adjustably supported in the base of the translator.

Fig. 6 is a similar mounting member adjustably supported in the cap of the translator;

Fig. 7 is a detail showing a modiiied form of mounting for the translating elements; K

Fig. 8 is an enlarged perspective view showing a preferred form of the spring contact wire; and

Figs. 9, 10, and 11 are details of the tip end of the contact wire.

As alluded to hereinbefore, it hasbeen-found that the best rectification results can be obtained in the ultra-high frequency range when the 'area of the contact point at which rectification occurs is extremely small. However, the minute size of this small contact area renders the translating device liable to damage when used in circuits carrying Van excessive amount of electrical power. The destruction orevenpartial impairment of the rectifying .point Adisables the entire system, making it necessary to remove the unit and to replace it with anew one. To obviate these'diniculties the translator structure about to/be'described is designed to use ltwo rectifyingcontacts Varranged in electrical series with each other .and in such close electrical proximity as to give the same effect as 4though the translator con- .tained but a single rectifying contact.

.Referring now to the drawings for a description of the translator structure, theprotective chamber in which thesmall crystals and contact Wires are housed is .formed bya hollowcylinder Iv of a ceramic having the requisite electricalV and mechanical properties. The cylinder I is threaded on itsinterior andcontains a lateral tapped bore f2 for receiving a-small set screw, the purpose of which will be Vexplained later.

The base or bottom member 3, which closes the lower end of the cylinder I, is preferably made of brass. This base member has an integral threadedstud 4 which `screws into the threaded opening in the end of the cylinder I. A concen-l tric bore passing through the entire length of the base 3 and integral stud 4 receives a small mounting pin 5 which supports one of the recti- If desirable the lower end of the central bore in the-base 3 may be enlarged and tapped to facilitate the manufacturing process and also for mounting purposes after the device has been assembled. The mounting pin 5 isfheld firmly in position by means of a set screw E located in a tapped lateral bore in the base `3.

The other end of the hollow cvlinderI is closed -by cap member 1 having a threaded stud 8 which screws into the end of the cylinder. 'The cap 'I is preferably of brass and also has a central bore which passes therethrough and Yserves to hold a second brass mounting pin 9 carrying one of the rectiiying elements. The mounting pin 9 is adiusted to its proper position by means of-a set screw I0 located in a tapped section of the central bore and is held firmly in its adjusted position by means of a lateral set screw II.

'Ihe enclosure within the insulating cylinder I is partitionedinto two chambers or compartments I2 and I3 by means of a small threaded supporting disc- I4, Disc I4 engages threads on the-interior of the cyli-nder I and maybe adjusted to any desired position within the cylinder by means of a tool designed lto engage the holes I5 in the surface of the disc. This disc supportson one of its faces one of the elements of one lrectier and on its opposite face one of the elements of the other rectifier.

. Since each of. the rectifying units consists of a small wafer of crystalline silicon and a. fine tungsten wire making a resilient point contact with the surface of the wafer, it will be seen that a number of mounting combinations are available in the structure herein disclosed. In the construction illustrated in Figs. 1, 3, 5 and 6, a crystal element I6 is mounted on the upper surface of the supporting disc I4, and a contact wire element I1 is mounted on the under surface of the disc. The contact wire element comprises the Vne resilient wire I1 and a small block I8 of brass or other suitable metal into which the end of the wire issoldere'd. The crystal I6V and the holder I8 are secured by soldering or otherwise to the surface of the disc I4, which is also preferably of brass to` alford a good electrical connection between the crystal and the contact wire. The other elements of the two rectiiiers are the resilient Vcontact wire I9 and the crystal wafer 29. The wire I9 is soldered into the end 0f the holding pin 9 which, as above explained, ts into the bore in the cap member 1; and the silicon crystal wafer 20 is soldered to the holding pin tl which is held withinthe kcentral bore in the base member 3.

Another possible alternative mounting is disclosed in-Fig. '7. Here the adjustable supporting disc 2I located within the insulating cylinder contains a central opening, which may be circular or any other desired configuration, for receiving two

crystal elements

22 and 23. These crystal elements 'are joined to each other electrically and are secured-Within the opening in the disc 2l-by soldering or any other suitable method. Iny this case the cooperating contact wires 24'and25 are held by the mounting pins 26 and 21-respectively which in turn are secured withinthe'cap and base members 1 and 5. Another alternative would be to mount the contact wires on opposite sides of the disc-2I and the associated crystals on the mounting pins 28 and 21. However, the methods illustrated in the drawings are' believed to be preferably for reasons which will be explained hereinafter.

Onemethod of assembling the translator will now be described. First a mountingV pin 5 having a crystal element 29 secured thereto is adjusted tothe desired position Within the base member 3, and the set screw' is applied to hold -thefpinrmly irl-position. Next the base member 3 is screwed into one end of the ceramic cylinder I. The adjustable supporting disc I4 to which acontact wi-re element I1 and arcrystal element I5 have `been secured is now adjusted within the cylinder I until the desired contact 'bringingtthe tip end of the spring wire I'9'into proximity with the surface of the crystal I6. `The nal step is to advance the set screw I9, the pin 9' being lightly held by the lateral screw II, until the desired contact engagement is eiected between the point of the contact wire i9 and the surface of the crystal I6. Then the set screw II is rmly applied to hold the pin 9 securely in position.

The electrical path through the assembled translator? may betraced from vthe metal ,cap 1,

base. I8, spring contact wire i1, crystal zii, metal mounting pin 'to `the base member 3. Since the alternating wave applied to the translator is undergoing rectification at both of the contact points, it is desirable to haveY the distance between these points assmall as Vpossible in comparison with the length' of the applied wave. This desirable result is achieved by the structure herein disclosed and'particularly by the alternative construction shown in Fig. 7. By placing the

crystals

22 and 23 back to back the distance between the two contact pointsis reducedto a minimum, and this distance may be made a small portion ofthe wavelength of the applied source, thus approaching the ideal condition.

It is essential, however,` that the assembled device shall conduct in the same direction through both of the rectifying units. Referring, for example, to Fig. 1 and assuming that the unit conducts from the crystal to the wire, it will be seen that current `*will flow from the pin 5, crystal 2B, wire I'I,` thence through the disc i4, crystal I6, wire I9 to the cap member 1. In Fig. 7, however, the rectifying units are arranged in the reverse order, andato-meet this situation Aand to take advantage oitheclose spacing permitted thereby the uniform direction of conduction may be preserved by selecting silicon material of opposite kinds for the elements 22 and 2S. For example, the silicon element 22 is made of electronegative material whereas the element 23 is of electropositive material. This means that current will ow in the circuit from the contacting pin 26, wire 24, crystal 22, crystal 23, wire 25, to the metal pin 21, whereas current will not flow in the opposite direction.

The preferred form of contact spring, shown greatly enlarged in Figs. 8, 9, and 11, is made from a length of ne round tungsten wire. The end 3l! of the wire is first ground to a conical point, following which the sides of the cone 3| are grounded or otherwise treated to form the two sets of opposing iiat surfaces as illustrated best in Fig. 11. The effect of this formation is to provide a nne rectangular area 32 which constitutes the rectication contact. Next the intermediate section 33 of the wire is flattened until it assumes the shape of a ribbon, .following which it is bent to give the necessary resilience. The upper end 34 is finally soldered into the end of the holder 35. This construction affords a relatively large surface for a given size of wire and makes it possible to obtain the necessary spring resilience with a minimum distance between the end of the holder 35 and the tip of the contact wire.

Although it is mentioned herein that the metal parts of the device are"preferably of brass, it will be understood that they may be made of other conducting materials. It will also be understood that these metal elements may be plated with a precious metaLvsuch as silver, to improve their conductivity. For a better understanding of silicon material of the positive and negative types used herein reference is made to the application of R. S. Ohl, Serial No. 385,425, led March 27, 1941, Patent Number 2,402,839, dated June 25, 1946.

Also it will be understood that the invention is not limited to the use of any particular materials for the rectifying elements, although sili- 6 conelements and tungsten wires are described herein as preferable. l i

What is claimed is:

l. The combination in a translating device of an insulating housing, a plurality of translating units mounted within said housing and connected in electrical series with eachother, each translating unit comprising an element of rectifying material and a ilne contact wire making apointcontact engagement with the surface of said element, andadjustable means mounted on said insulating housing for adjusting the pressure of each of said contact wires on the associated rectifying element.

2. The combination Vin a transilating device of an insulating housing, a pair of rectifying units mounted in series within said housing and in close electrical proximity with each other, each rectifying unit comprising an element of rectifying material and a fine resilient contact Wire making a point-contact engagement with the surface of said element, and means for adjusting the pressure of each of said contact wires on the associated ,rectifying element. l

3. The combination in a translating device of an insulating housing, `an adjustable supporting member within said housing, a pairV of translating units within said housing, each unit comprising two rectifying elements, one a body of rectifying material and the other a contact wire making a point-contact engagement with the surface of said body, one of the rectifying elements of one translating unit being mounted on one side and one of the rectifying elements of the other translating unit being mounted on the other side of said supporting member, and means for supporting the other element of each of said translating units.

fl. The combination in a translating device of a hollow cylinder of insulating material, an adjustable supporting member within said cylinder and separating it into two compartments, a pair of translating units, each unit comprising two rectifying elements, one a crystal body and the other a contact wire making a point-contact engagement with the surface of said crystal body, one of the rectifying elements of one translating unit being mounted on one side and one of the rectifying elements of the other translating unit being mounted on the other side of said adjustable supporting member, a base member closing the compartment in one end of said insulating cylinder, a cap member closing the compartment in the opposite end thereof, and adjustable devices mounted within said base and cap members for supporting the other elements respectively of said translating units.

5. The combination in a translating device of a hollow insulating cylinder, an adjustable supporting member within said cylinder separating it into two chambers, a pair of crystal rectifying elements mounted on opposite sides of said supporting member and lying respectively in the chambers formed by said supporting member, a ne contact wire making a point-contact engagement with the surface of one of said crystal elements and a similar contact wire making a point contact engagement with the other of said crystal elements, and a pair of members closing the chambers in the opposite ends of said cylinder and serving as supports for said contact wires.

6. The combination in a translating device of an insulating housing member, a pair of rectifying units mounted within said housing member anestesia Z and connected in electrical series with each other, each translating unit comprising a crystal body of rectifying material and anne contact Wire vmaking a point-contact engagement with the surface'oi saidelement, said crystal bodies having different rectiiying characteristics, and means for adjusting-said translating units.

'1. The combination in a translating device of an insulating housing member, a plurality of translating units mounted Within said housing member and connected in electrical series with each other, one of said translating units comprising a'crystal body of positive'rectifying material and a ne contact wire making a pointcontact engagement with the surface of said element, the other translating unit comprising a crystaly body of negative rectifying material and a' ne'contact Wire making a point-contact enf'gagementwith the surface thereof, and means fork adjusting the relation between the contact Wire land Ycrystal body of each of said translating-units.

ySf'I'he combination ina translating device of an insulating housing, a pair of rectifying units mounted in series Within said housing and in cl'oseelectrical proximity With each other, each recti'ying unit comprising an element of rectifying material and a ne contact Wire, the tip endof' which is shaped t0 make a contact engagement of minute'area with the surface of said rectifying element, the intermediate section of said'wire being ribbon-shaped to give it a relatively large'surfaeefareafand having al num,- ber of 'turns to'gire it resilience, and means for adjusting'the pressure ofeach. oisaid contact Wires on the'assciatedfrectifyig'element. Y

9. The "comb'inationy in a'translatingfdevice of an insulating housing, aV plurality 'of separate translating units' mounted 'vizithln said housing and connected in electrical series with each other, each translating unit' comprising an element of rectifying material' anda contact Wire making a `point=contact 'engagementwth the surface of said element, and means for performing a separate adjustment of'each ofy said contact wires with respectv to its/associated element of'rectifying material. I l

CRL A. BIELING.. REFERENCES- CITED The followingreferences are Vci record in the le of this patent:

UNITEDSTATES PATENTS Number Name Date 1214,022 Edelman Jan. 30, 1917 FQREIGN PATENTS Number Country Date 220,473 Great BritainY Aug.'2l, 1924 223,702 Greabritain Oct. 30, 1924 253,746