Gas tube surge protective device and method for making the device

Claim 2

A surge protective device which comprises: a. an insulative housing having a bore extending therethrough; b. a first electrode disposed at one end of the housing and having a member extending into the bore of the housing; c. a second electrode disposed at the other end of the housing bore in spaced relation to the first electrode to form a gap therebetween and closing the housing bore to form a chamber for ionizable gas; and d. a starter electrode deposited on the wall of the housing bore and joined to the second electrode, said starter electrode extending along the wall of the housing bore to circumscribe a portion of the member of the first electrode to initiate the ionization of the gas and provide reproducibility of breakdown voltage.

Claim 3

A surge protective device, as recited in claim 1, wherein: a. the insulative housing is ceramic having a counterbore at one end of the bore; and b. the first electrode has a shoulder substantially concentric, complimentary with and spaced from the counterbore to provide a setback shielded from sputtered material to prevent shorting of the electrodes.

Claim 4

A surge protective device, as recited in claim 2, wherein the member extending into the bore also extends past the midlength of the bore so that the gap is located remote from the counterbored end to lengthen the life of the device.

Claim 5

A surge protective device, as recited in claim 1, wherein the first and second electrodes are copper.

Claim 6

A surge protective device, as recited in claim 1, wherein the starter electrode is other electrode material sputtered on the wall of the housing bore.

Claim 7

A surge protective device which comprises: a. a tubular insulative housing having a counterbore at one end to form a setback; b. a first copper electrode disposed at the counterbored end of the housing, said first electrode having shoulder spaced substantially concentrically from and complimentary with the counterbore to shade the setback and prevent sputtered material on the inner wall of the tubular housing from contacting the first electrode, said shoulder having a cylindrical portion extending coaxially therefrom into the bore of the tubular insulative housing past the midpoint and in spaced relation to the inner wall thereof, the face of said cylindrical portion being distant from the counterbored end of the housing; c. a second copper electrode disposed at the other end of the housing, said second electrode having a conical frustrum portion extending coaxially into the bore of and in spaced relation to the inner wall of the tubular insulative housing, the face of the conical frustrum portion of the second electrode being spaced from the face of the cylindrical portion of the first electrode to form the device arc gap, said first and second electrodes and housing forming an enclosed chamber for a gas capable of rapid ionization upon application of a surge voltage to the electrodes; and d. a starter electrode joined to said second electrode, said starter electrode being electrode material sputtered onto the inner wall of the housing to form a shell electrically joined to the second electrode and circumscribing at least a part of the cylindrical portion of the first electrode to form an annular space between said starter electrode and cylindrical portion, said space being smaller than said device gap, and said starter electrode initiating discharge in the ionizable gas at a uniform level.

Claim 8

A surge protective device which comprises: a. a tubular insulative housing having a counterbore at one end to form a setback; b. a first copper electrode disposed at the counterbored end of the housing, said first electrode having shoulder spaced substantially concentrically from and complimentary with the counterbore to shade the setback and prevent sputtered material on the inner wall of the tubular housing from contacting the first electrode, said shoulder having a cylindrical portion extending coaxially therefrom into the bore of the tubular insulative housing past the midpoint and in spaced relation to the inner wall thereof, the face of said cylindrical portion being distant from the counterbored end of the housing; c. a second copper electrode disposed at the other end of the housing, said second electrode having a conical frustrum portion extending coaxially into the bore of and in spaced relation to the inner wall of the tubular insulative housing, the face of the conical frustrum portion of the second electrode being spaced from the face of the cylindrical portion of the first electrode to form the device arc gap, said first and second electrodes and housing forming an enclosed chamber for a gas capable of rapid ionization upon application of a surge voltage to the electrodes; and d. a starter electrode joined to said second electrode, said starter electrode being electrode material sputtered onto the inner wall of the housing to form a shell electrically joined to the second electrode and circumscribing at least a part of the cylindrical portion of the first electrode to form an annular space between said starter electrode and cylindrical portion, said space being smaller than said device gap, and said starter electrode initiating discharge in the ionizable gas at a uniform level.

Claim 9

In combination with a surge protective device of the type wherein a tubular insulative housing is closed at one end by a first electrode having a cylindrical member extending into the bore of the housing and at the other end by a second electrode in spaced relation to the first electrode to form a discharge gap within a chamber for ionizable gas, the improvement, which comprises: a starter electrode deposited on the inner wall of the housing and joined to the second electrode to initiate ionization of the gas and maintain the initiation at a uniform level.

Claim 10

In combination with a surge protective device of the type wherein a tubular insulative housing is closed at one end by a first electrode having a cylindrical member extending into the bore of the housing and at the other end by a second electrode in spaced relation to the first electrode to form a discharge gap within a chamber for ionizable gas, the improvement, which comprises: a starter electrode deposited on the inner wall of the housing and joined to the second electrode to initiate ionization of the gas and maintain the initiation at a uniform level.

Claim 11

A surge protective device, as recited in claim 7, wherein the starter electrode is other electrode matErial sputtered on the inner wall of the housing.

Claim 12

A surge protective device, as recited in claim 8, wherein the device includes a setback at one end and the discharge gap at the other.

Claim 15

A method of making a gas-filled surge protector, as recited in claim 10, wherein conductive material is deposited by sputtering.

Claim 16

A method of making a gas-filled surge protector, as recited in claim 11, wherein the cylindrical member extends into the bore past the midlength to locate the gap in proximity to the end of the housing.