US3500010A - Electromechanical switch - Google Patents

Description

March 10, 1970 A. HAREL 4 3,500,010

ELECTROMECHANICAL SWITCH Filed May 21. 1968 .HBMHAM HaneL armnr United States Patent US. Cl. 200-166 6 Claims ABSTRACT OF THE DISCLOSURE An electromechanical switch for use where resilient materials may not be practicable has a relatively hard contact, a malleable contact, and a device for re-shaping the malleable contact prior to each of its engagements with the hard contact.

BACKGROUND OF THE INVENTION This invention was made in the course of or under a contract or subcontract thereunder with the Department of the Air Force. The invention relates to the art of electromechanical switches and pertains more particularly to an electromechanical switch for use in an environment in which resilient materials cannot be effectively employed.

In an electromechanical switch, there is ordinarily a fixed contact element and a movable contact element which is adapted to be brought into and out of engagement with the fixed contact element. The efficiency of the contact is dependent on, among other things, the force or pressure between the two contact elements. Customarily, resilient biasing means are used to provide the pressure necessary for good, low resistance contact. The materials of which the contact elements are made may themselves be resilient, or separate springs may be used to bias the elements together.

Under certain conditions, springs or resilient contact materials may not be practicable. For example, high temperatures may cause resilient switch materials to lose their elasticity. In very clean systems, non-resilient, inert materials such as pure gold may have to be used so as not to contaminate the system.

More particularly, in vacuum evaporation systems used in the manufacture of microelectronic devices and the like, electrical resistance heaters are used to evaporate materials which are to be deposited as films on a support or substrate. Typically, several heaters are employed within a single vacuum chamber and each is adapted to be moved selectively into a position from which evaporation is desired. Current must be supplied from outside the system to each heater individually.

Because of the high temperatures within a vacuum chamber near the resistance heaters, it has been difficult heretofore to provide switch contacts within the chamber near the heaters. Consequently, contacts have been placed within a vacuum chamber at a considerable distance from the heaters, resulting in the loss of valuable space, or separate conductors for supplying current to each heater have been led out through the wall of the chamber to switching means located outside the chamber. Such arrangements unduly complicate the structure of the chamber. It is desirable, on the contrary, that the number and complexity of openings through the wall of the chamber be kept to a minimum..

SUMMARY OF THE INVENTION The present novel electromechanical switch has a relatively hard contact and malleable contact. The malleable contact is adapted to be bent or otherwise deformed by engagement with the hard contact. A reshaping means 3,500,010 Patented Mar. 10, 1970 is included in the switch and is engageable by the malleable contact to force it in the direction opposite to the direction in which it is deformed by engagement with the hard contact. By this means, the malleable contact may be reshaped prior to each engagement with the hard contact, and, consequently, the switch may be used eificiently in spite of adverse conditions such as high temperature.

THE DRAWINGS FIG. 1 is vertical cross section through a portion of a vacuum evaporation system showing the contact elements of the present electromechanical switch in the closed condition;

FIG. 2 is a cross section on the line 22 of FIG. 1 showing, in phantom, another position of the movable contact elements of the present switch;

FIG. 3 is a partial cross section on the line 33 of FIG. 2.

PREFERRED EMBODIMENT The present electromechanical switch is illustrated in the drawings as applied to a resistance heating device adapted for use in a high vacuum, high temperature environment such as a thin film evaporator, for example. The resistance heating device includes a plurality of conical resistance wire coils, 12 and 14, in which a material may be heated to evaporate it for deposition on a substrate, not shown, located elsewhere in the system.

The resistance coils 12 and 14 are supported on a turntable 16 which is mounted on a shaft 18 adapted to be rotated about its longitudinal axis to position each of the coils selectively at a location from which evaporation is desired. The turntable 16 includes a central bushing 20 which is attached to the shaft 18 by means of a fastener 22. Attached to the bushing 20 is an annular disc 24. L- shaped parts 26, one for each resistance coil, are supported on the disc 24 and are separated therefrom by spacer blocks 28 made of insulating material. Each part 26 has a horizontal leg 30 and a vertical leg 32. Fasteners 34 connect the spacer blocks 28 to the disc 24 and fasteners 36 connect each L-shaped part 26 to the spacer blocks 28. The resistance coils 12 and 14 are each connected, as by clamping screws 37, between the upper end of a leg 32 of an L-shaped part 26 and the bushing 20.

The fasteners 36 also serve to attach a contact block 38 to the lower side of the horizontal leg 30 of each L- shaped part 26. Each contact block 38 carries a forklike contact comprising a pair of spaced contact fingers 42 and 43. The contact fingers 42 and 43 are made of malleable material, such as vacuum grade copper.

The contact fingers 42 and 43 are adapted to engage a fixed, relatively hard contact pin 48 which is supported by a contact block 50. The contact block 50 is mounted on a fixed plate 52 by means of a pair of fasteners 54 (FIGURE 2). Preferably, the pin 48 is inserted with a press fit into a suitable bore 56 in the block 50. In this example, the pin 48 has an enlarged head 58 thereon, as shown.

Each of the contact fingers 42 and 43 is provided with an internal recess so that weakened areas 59 and 60 and ledges 61 and '62, respectively, are defined. The weakened areas 59 and 60 facilitate the bending of the contact fingers 42 and 43. The ledges 61 and 62 may engage the underside of the head 58 to limit deflection of the entire turntable assembly 16 in the axial direction of the pin 48, which deflection may result from the axial component of the force of the engagement between the pin 48 and the contact fingers 42 and 43.

Also carried by the contact block 50 is a reshaping means comprising a pair of spaced pins 64 and 65. The pins 64 and 65 are preferably held by means of a press fit in spaced bores 68 and 69 in the block 50. As suggested 3 in FIG. 2, the pins 64 and 65 are directed radially with respect to the shaft 18. The spacing between the pins 64 and 65 is such that the contact fingers 42 and 43 will be pressed toward each other as rotation of the shaft 18 forces them past the pins 64 and 65. After passing between the pins 64 and 65, the contact fingers 42 and 43 will retain the bent condition imparted to them bv the pins 64 and 65.

The electrical components of the present system include a battery 70 which preferably is located outside the vacuum chamber. One side of the battery 70 is connected to the plate 52 and the other side of the battery is connected to ground. The shaft 18 is also connected to ground through a connection symbolically shown at 72.

In operation, the turntable 16 of the device is rotated intermittently to bring each of the heater coils, such as the heater coil 12 in FIG. 1, for example, into position from which the evaporation of the material therefrom is intended to take place. This position may be determined by indexing means (not shown) operably connected to the shaft 18 outside the vacuum system. When the turntable 16 is brought into position, the contact 42 and 43 of the movable contact 38 associated with the heater coil 12 engage the fixed contact pin 48. This completes the circuit from the battery 60, through the plate 52, the contact block 50, the fixed contact pin 48, the movable contact fingers 42 and 43, the contact block 38, and the L-shaped part 26 to the heater coil 12. From the heater coil 12, the circuit is completed back to ground through the bushing 20, the shaft 18, and the ground connection 72. Since each L-shaped part 26 is isolated by the insulating spacer blocks 28, only one heater coil at a time receives current from the battery 70.

After a desired amount of material has been evaporated, the shaft 18 is rotated to disconnect the movable contact fingers 42 and 43 from the contact pin 48. Because they are malleable, the pins 42 and 43 will remain in the bent condition imparted to them by the engagement with the pin 48. Upon rotation of the turntable 16 to again bring these contact fingers into engagement with the pin 48, they will first encounter the spaced reshaping pins 64 and 65. The pins 64 and 65 will force the contact fingers 42 and 43 toward each other, as the shaft is rotated. Thus, the contact fingers will be bent back in the direction opposite to the direction in which they were bent during contact with the pin 48, to a separation distance less than the diameter of the pin 48. Accordingly, when they again contact the pin 48, they are in a condition such that contact pressure is restored. The contact fingers 42 and 43 associated with each of the other heater coils in the device will be acted upon similarly and will operate in the same manner,

What is claimed is: 1. Electromechanical switch means comprising a relatively hard contact element, a malleable contact element, means mounting said hard and said malleable contact elements for relative motion therebetween into and out of engagement with each other, said malleable contact element being adapted to be deformed in one direction upon engagement with said hard contact element, and means engageable by said malleable contact element prior to engagement with said hard contact element for causing said malleable contact element to be deformed in a direction opposite to said one direction. 2. Electromechanical switch means as recited in claim 1, wherein said hard contact element is fixed in position and said malleable contact element is movable with respect thereto.

3. Electromechanical switch means as recited in claim 1 wherein said hard contact element comprises a cylindrical pin,

said malleable contact element comprises a pair of spaced fingers adapted to engage said pin at diametrically opposite locations thereon, and said engageable means comprises means for bending said fingers toward each other to a spacing less than the diameter of said pin. 4. Electromechanical switch means as recited in claim 3 wherein said cylindrical pin has an enlarged cylindrical head and said spaced fingers each have a recess defining a ledge engageable by said head to limit motion of said malleable contact element in the direction of the axis of said cylindrical pin.

5. Electromechanical switch means as recited in claim 3 wherein said malleable contact element is mounted for translational movement in an arcuate path about a fixed axis, and

said hard contact element and said engageable means are located in said path. 6. Electromechanical switch means as recited in claim 5 wherein said engageable means comprises two spaced pins separated by a distance such that engagement of said fingers therewith forces said fingers toward each other.

References Cited UNITED STATES PATENTS 2,918,541 12/1959 Waite. 3,045,090 7/ 1962 Wilson et al. 3,301,971 1/1967 Johnson. 3,382,340 5/1968 Moodie et al.

HERMAN O. JONES, Primary Examiner US. Cl. X.R. 00-1 1

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