# US 7,609,135 B2 · Switching apparatus with voltage spike prevention > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,609,135 B2 - Document ID: US7609135B2 - Status: Granted - Kind: B2 - Application number: 10/987,418 - Filed: 2004-11-12 - Published: 2005-10-20 - Granted: 2009-10-27 - Earliest claimed: 2004-04-14 - Assignees: Tektronix, Inc. - Inventors: Kei-Wean Calvin Yang - Web page: https://patentgrep.com/patent/US7609135B2 ## CPC - H01H 50/10: Electromagnetic or electrostatic shielding (casings H01H50/02) - H01H 9/12: Means for earthing parts of switch not normally conductively connected to the contacts - H01H: ELECTRIC SWITCHES; RELAYS; SELECTORS; EMERGENCY PROTECTIVE DEVICES (contact cables H01B7/10; electrolytic self-interrupters H01G9/18; emergency protective circuit arrangements H02H; switching by electronic means without contact-making H03K17/00) ## Abstract A switching apparatus has a conductive housing forming a chamber. The housing has an aperture enabling communication between the chamber and a housing exterior. A rod extends through the aperture, and has a first end within the chamber, and an opposed second end outside the chamber. The rod reciprocates over a range of motion between a first position in which a limited portion of the rod extends into the chamber, and a second position in which a greater portion of the rod extends into the chamber. The rod has a electrically insulative portion electrically isolating the first end from the second end, and has a conductive surface contacting the housing. A pair of electrical contacts are located in the chamber, and a shorting bar connected to the first end of the rod operates to bridge the contacts when the rod is in a selected position. ## Claims ### Claim 1 A switching apparatus comprising; a conductive housing defining a chamber; the conductive housing defining an aperture providing communication between the chamber and a housing exterior; a rod extending through the aperture, and having a first end within the chamber, and an opposed second end outside the chamber; the rod having a cap portion at the second end; the rod being operable to reciprocate over a range of motion between a first position in which a limited portion of the rod extends into the chamber, and a second position in which a greater portion of the rod extends into the chamber; the rod having a electrically insulative portion electrically isolating the first end from the second end; the rod having a conductive surface contacting the housing; a spring substantially surrounding the portion of the conductive surface of the rod not extending into the chamber, the spring being bounded by a lower surface of the cap, and a surface of the conductive housing; a pair of electrical contacts in the chamber; and a shorting bar connected to the first end of the rod and operable to bridge the contacts when the rod is in a selected position; wherein when said rod is moved to said second position, said conductive surface remains outside of said chamber. ### Claim 2 (depends on 1) The apparatus of claim 1 wherein the aperture is a circular bore, and wherein the rod's conductive surface is a cylindrical surface. ### Claim 3 (depends on 1) The apparatus of claim 1 wherein the rod is an elongated dielectric body having a metallic surface about an intermediate portion. ### Claim 4 (depends on 1) The apparatus of claim 1 wherein the conductive surface is a metal sleeve. ### Claim 5 A switching apparatus comprising; a conductive housing defining a chamber; the housing defining an aperture providing communication between the chamber and a housing exterior; a rod extending through the aperture, and having a first end within the chamber, and an opposed second end outside the chamber; the rod being operable to reciprocate over a range of motion between a first position in which a limited portion of the rod extends into the chamber, and a second position in which a greater portion of the rod extends into the chamber; the rod having a electrically insulative portion electrically isolating the first end from the second end; the rod having a conductive surface contacting the housing; a pair of electrical contacts in the chamber; and a shorting bar connected to the first end of the rod and operable to bridge the contacts when the rod is in a selected position; wherein when said rod is moved to said second position, said conductive surface remains outside of said chamber; wherein said conductive surface is a metal sleeve; and wherein the sleeve surrounds a dielectric portion, and including a compound of limited conductivity between the sleeve and the dielectric portion. ### Claim 6 (depends on 1) The apparatus of claim 1 wherein the conductive surface is an applied film of liquid. ### Claim 7 (depends on 1) The apparatus of claim 1 wherein the conductive surface is a metal coating. ### Claim 8 (depends on 1) The apparatus of claim 1 wherein the rod has a metal intermediate portion, and with a dielectric end portion at each end of the metal portion. ### Claim 9 (depends on 1) The apparatus of claim 1 wherein when the rod is moved to the second position, the conductive surface remains outside of the chamber. ### Claim 10 (depends on 9) The apparatus of claim 9 wherein when the rod is moved to the second position, the conductive surface is adjacent to an inner surface of the chamber. ### Claim 11 (depends on 1) The apparatus of claim 1 wherein the conductive surface defines a gap, such that it does not continuously encircle the rod. ### Claim 12 An electronic instrument having a switching apparatus comprising; a conductive housing defining a chamber; the housing defining an aperture providing communication between the chamber and a housing exterior; a rod extending through the aperture, and having a first end within the chamber, and an opposed second end outside the chamber; the rod having a cap portion at the second end; the rod being operable to reciprocate over a range of motion between a first position in which a limited portion of the rod extends into the chamber, and a second position in which a greater portion of the rod extends into the chamber; the rod having a electrically insulative portion electrically isolating the first end from the second end; the rod having a conductive surface contacting the housing; a spring substantially surrounding the portion of the conductive surface of the rod not extending into the chamber, the spring being bounded by a lower surface of the cap, and a surface of the conductive housing; a pair of electrical contacts in the chamber; and a shorting bar connected to the first end of the rod and operable to bridge the contacts when the rod is in a selected position; wherein when said rod is moved to said second position, said conductive surface remains outside of said chamber. ### Claim 13 (depends on 12) The instrument of claim 12 wherein the rod is an elongated dielectric body having a metallic surface about an intermediate portion. ### Claim 14 (depends on 12) The instrument of claim 12 wherein the conductive surface is a metal sleeve. ### Claim 15 (depends on 12) The instrument of claim 12 wherein the conductive surface is a metal coating. ### Claim 16 (depends on 12) The instrument of claim 12 wherein when the rod is moved to the second position, the conductive surface remains outside of the chamber. ### Claim 17 (depends on 4) The apparatus of claim 4, wherein the metal sleeve is substantially cylindrical, has a first end and a second end, and said sleeve defines a gap from said first end to said second end such that it does not continuously encircle said rod.