US2410041A

US2410041A - Piezoelectric crystal cabinet

Info

Publication number: US2410041A
Application number: US481427A
Authority: US
Inventors: Samuel A Bokovoy
Original assignee: Standard Telephone and Cables PLC
Current assignee: STC PLC; Federal Telephone and Radio Corp
Priority date: 1943-04-01
Filing date: 1943-04-01
Publication date: 1946-10-29
Anticipated expiration: 1963-10-29
Also published as: BE460505A; CH254389A; FR939013A; GB580057A

Description

Oct. 29, 1946. s. A. BoKovoY 2,410;041

PIEZOELECTRIC CRYSTAL CABINET Filed April 1, 1943 4 Sheets-Sheet 1 IN VEN TOR.

Oct. 29, 1946. s. A. BOKOVOY 2,410,041

PIEZOELECTRIC CRYSTAL CABINET Filed April 1, 1943 4 Sheets-Sheet 2 0 w 1 4 m M w INVENTOR. SAMUEL ABo/rovoY 12W J) ATTORNEY Oct. 29, 1946. 5 BOKQVOY 2,410,041

PIEZOELECTRIQ CRYSTAL CABINET Filed April 1, 1943 4 Sheets-Sheet 3 13 INVENTOR.

Patented Oct. 29, 1946 PIEZOELECTRIC CRYSTAL CABINET Samuel A. Bokovoy, Verona, N. J assignor to Federal Telephone and Radio Corporation, New York, N. Y., a corporation of Delaware Application April 1, 1943, Serial No. 481,427

7 Claims.

This invention relates to enclosed cabinet mountings especially adapted for piezo-electric crystals and provided With an improved arrangement for maintaining the crystals at uniform temperature during wide changes in circumambient temperatures.

The mounting includes a cabinet construction comprising a plurality of nested chambers with the crystals in the central chamber, provided with a thermostat-controlled heating element. A feature of the invention is a provision of a novel construction and arrangement of the chambers, thermostat and heater which will eiiectively re tard the transfer of outside temperature changes to the crystal chamber and facilitate the operation of the heater to compensate for such changes before they can reach the crystal chamber. The invention includes the use of an improved in-, ternal chamber wall construction made of metal having good thermal conductivity arranged to provide uniformity of heat transfer to the thermostat and from the heater.

A further purpose is to provide a temperaturecontrolled cabinet suitable for mounting a plurality of piezo-electric crystals arranged so that the, various crystals can be connected into circuits in any desired manner without disturbing the cabinet. Another object is the provision of an improved crystal cabinet of the indicated type which is adapted for mounting in a standard type of pin socket.

Other objects and advantages will appear from the following description considered in connection with the accompanying drawings, in which: v. Fig. 1 is a front elevation of a cabinet embody- I ing the invention with parts broken away, the

connecting leads being omitted;

Fig. 2 is a transverse section on line 22 of Fig. 1;

Fig. 3 is a vertical section on line 33 of Fig. 2;

Fig. 4 is a vertical section on line 4-4 of Fig. 2; and

Fig. 5 is a diagram of circuit connections.

The cabinet I0 comprises an outer base ll of insulating material provided with a plurality of hollow contact pins P set into the lower face of the base, together with a positioning stud l2 provided with a longitudinal lug l3, said contact pins, stud and lug being of the type usually employed on radio tube bases, arranged for insertion in tube sockets of the type ordinarily employed in radio apparatus.

An outer housing or hollow cover 14 of insulating material is fitted to base I l to form a completely enclosed chamber. In the form illustrated the housing I4 is generally rectangular in crosssection, being provided with enlarged vertical corner portions l5 (Fig. 2); and the base It is provided with housing positioning lugs l8 fitting against the side walls of housing l4 intermediate the enlargements IS. A suitable gasket II which may be of natural or synthetic rubber or the like is interposed between base I l and housing [4, the latter being held in place by screws 18 extending upwardly through the corners of base ll into the enlarged corner portions l5 (Fi 4).

The piezo-electric crystals are mounted on inner base 20 whichis formed of insulating material and mounted on a pedestal 2| by screw 22 (Fig. 3) which is preferably countersunk and covered with insulating material 23 such as glyptal resin. A rectangular positioning bar 24 may be fitted into registering slots in the contiguous faces of the inner base 20 and pedestal 2|.

Suitable crystal supports are mounted on inner base 20 and are advantageously arranged to provide proper support for a plurality of piezo-electric crystals, together with the appropriate electrodes and leads which advantageously extend through the base 20 and are connected to the contact pins P. In the form illustrated three sets of crystal mounting spring clips 25 are supported on base 29, each including a contact spring 26 engaging one face of a crystal 21, and a nonconducting post 28 engaging the opposite face and extending into a socket 29 (Fig. 4) in base 2! The clips 25 are arranged to support three crystals 2! in parallel position equally spaced from each other and from parallel margins of base 20. The clips for each crystal are arranged with the contact springs 26 engaging opposite faces of the crystal, which is provided with metallic surface contact elements such as metal platin extending over the opposite sides of the crystal in known manner. A lead 36 extends from each contact spring 26 through a registering hole 3| in base 20 into the channel 32 extending around and beneath the lower margin of the base 20 and communicating with the upper ends of hollow pins P into Which the leads 30 pass, each lead being connected to the associated pin by a solder tip 33 in the usual manner.

A wall made of a metal having good thermal conductivity is mounted on inner base 20 surrounding the crystals, and forms with outer housing I4 an outer compartment 35. The wall carries a suitable thermostat and a heater located in the outer compartment. In the form illustrated the wall is in the form of a metal housing 36 advantageously made of aluminum and fitting over the outer face of base 20, being suitably held in place thereon as by screws 31. The heater consists of a winding 38 of suitable heater wire such as nichrome wound on the outer face of housing 36, and may be held in place by insulating varnish. The thermostat 39 is of the standard enclosed bimetallic type with terminals at opposite ends and is mounted on the upper part of housing 36, extruding through openings at opposite sides of the housing with its terminals 49 projecting into the outer compartment 35.

An inner crystal housing 41 of insulating material is advantageously mounted on inner base 20 surrounding the crystals 21 and located within the metal housing 36. In the form illustrated the inner housing 4| has a lower edge fitting snugly against the base 20 and is held removably in place thereon by downwardly projecting tongues 42 (Fig. 4) at opposite sides fitting snug- 1y against the inner walls of registering recesses in the outer portions of base 20. The walls of the inner housing 4| are advantageously spaced from the metal housing 36 and form an inner or central crystal compartment 42 and an intermediate or central compartment 43 between

housings

4 and 38.

One end of the heater winding 38 is connected to one terminal 40 of the thermostat 39 while the other end of said winding as well as the opposite terminal 40 of the thermostat are connected by suitable leads extending downwardly through the outer chamber 35 and channel 32 to appropriate contact pins P to which they are electrically connected in the manner already indicated. The terminal 40 of thermostat 39 to which the winding 38 is connected may also be connected through a suitable lead to another pin P in similar manner to facilitate the connection of a condenser across the thermostat. A suitable arrangement for connecting the crystals 21, heater winding 38 and thermostat 39 to the various contact pins is shown diagrammatically in Fig. 5.

In the arrangement described and illustrated the crystals 2'! are located in an insulating dead air chamber 42 surrounded by a dead air chamber 43. Any change in the ambient temperature outside of the outer housing [4 will be conducted gradually to the outer compartment 35 where it will affect thermostat 39 promptly through conduction from both ends of the thermostat and through the metal housing 36. This will result in prompt energizing of the heater winding 38 when the temperature drops below the normal temperature for which the thermostat is set and promptly corrects the temperature drop in the outer compartment 35 before it has an opporunity for appreciable transmission through the intermediate compartment 43 and inner housing II to the crystal compartment 42. The transmission of temperature changes to the latter compartment through the bases is negligible owing to the very thick base construction, the reductions in the conducting path by the use of a restricted pedestal 2| and the absence of good thermally conducting parts.

The arrangement has been found so effective in practice that it has proven to be capable of limiting the variations in the rate of crystal oscillation caused by changes in temperature to not more than about cycles per million during ambient temperature changes between 48 and +60 Fahrenheit and even with substantial variations in heater voltages, such as changes between 22 and 28 volts. The cabinet i extremely compact and small, and is arranged for ready construction and assembly as well as convenient installation and replacement.

The parts referred to as made of insulating material are formed from materials having not only the necessary electrical insulating properties but also high thermal insulating value. Various synthetic resins have the requisite qualities and are adapted for ready molding or pressing into parts of the types illustrated and described.

What is claimed is:

1. A temperature-controlled piezo-electric crystal mounting comprisin a base, an outer housing mounted on the base, said base and housing being formed of thermal insulating material, a thermally conducting metal housing spaced from the outer housing, a heater and a heater-controllin thermostat mounted on the metal housing, and an inner housing enclosing the crystal supports located Within and spaced from the metal housing.

2. A temperature-controlled piezo-electric crystal mounting that comprise a base, an inner housing formed of insulative material mounted on said base and definin a crystal chamber, an outer housing disposed in spaced relationship to the inner housing and defining therewith a heatinsulated space, a heat-conducting housing within said space disposed in spaced relationship to the inner housing, an electric heater supported upon the heat-conducting housing, and a thermostat supported upon the heat-conducting housin controlling operation of the heater and responsive to temperature variations Within the outer housing.

3. A temperature-controlled piezo-electric crystal mounting that comprises a base, an inner housing formed of insulative material mounted on said base and defining a crystal chamber, an outer housing disposed in spaced relationship i to the inner housing and defining therewith a heat-insulated space, a heat-conducting housing within said space disposed in closely spaced relationship to the inner housing, an electric heater supported upon the heat-conducting housing, and a thermostat supported upon the heat-conducting housing controlling operation of the heater and responsive to temperature variations within the outer housing,

4. A mounting according to claim 2 in which the inner and outer housings are formed of heatinsulating material,

5. A mounting according to claim 2 in which the base is supported upon a pedestal formed on a inner portion of the outer housing.

6. A mounting according to claim 2 in which a, central portion of the base is supported upon a pedestal formed on an inner portion of the outer housing.

7. A mounting according to claim 2 in which only a central portion of the base is supported upon a pedestal formed on an inner portion of the outer housing, while a remaining poition of said base forms, in conjunction with the portion adjacent said pedestal, a channel for leads con necting contact pins with associated crystals.

SAMUEL A. BOKOVOY.