WO2005089435A2

WO2005089435A2 - Contact structure for a switch

Info

Publication number: WO2005089435A2
Application number: PCT/US2005/008925
Authority: WO
Inventors: Neil R. Aukland; Thomas J. Schoepf; George Albert Drew; Gerd Rudolph
Original assignee: Delphi Technologies, Inc.
Priority date: 2004-03-18
Filing date: 2005-03-17
Publication date: 2005-09-29
Also published as: WO2005089435A3; EP1728258A4; EP1728258B1; US6979786B2; EP1728258A2; US20050205396A1

Abstract

A contact structure for a sliding switch includes a conductive stationary contact (120) disposed on a base (112) and a conductive movable contact (124) for electrically contacting the stationary contact (120). The movable contact (124) is movable along a path (A, B) between a current-inhibiting position and a current-permitting position with respect to the stationary contact (120). At least one of the contacts (120, 124) has a protruding portion (144a, 144b) that provides an electrical interface for discharge of arcing as the movable contact (124) terminates electrical interface for discharge of arcing as the movable contact (124) terminates electrical communication with the stationary contact (120). As a result, the invention prevents, or substantially reduces, degradation in switch performance, which might otherwise be caused by debris accumulation associated with arcing.

Description

CONTACT STRUCTURE FOR A SWITCH

TECHNICAL FIELD [0001] The present invention relates generally to the structure of contacts of a sliding switch and, in particular, to the structure and relative movement of stationary and movable switching contacts.

BACKGROUND OF THE INVENTION [0002] There is a growing demand for sliding switches that use printed circuit boards, wire frames, and the like as stationary contacts. Such switches are used in vehicles (e.g., to control lights, turn signals, etc.), in household devices (e.g., as program switches for washers and dryers, etc.), and many other applications. [0003] A conventional arrangement and structure of contacts of a sliding step switch is shown in Figs. 12-14. The arrangement depicts a three-function configuration 510 for a sliding switch. In this arrangement, a first conductive stationary contact pad 514, connected to a positive terminal of a power source, is disposed on a circuit board substrate 512, which is formed of an insulating material such as synthetic resin. Second, third, and fourth conductive stationary contact pads 516, 518, 520, connected to a negative terminal of a power source via a ground connection, are also disposed on substrate 12. An insulating material 522, such as a solder mask, is disposed between contact pads 514, 516, 518, 520. [0004] A movable contact assembly 524 is mounted to an un-illustrated holder, which permits movement of assembly 524 in the directions indicated by arrows A and B. Movable contact 524 includes first and second cylindrical, movable, conductive contact heads 526,

X 528 mounted to respective, conductive contact springs 530, 532. Contact springs 530, 532 are electrically coupled to one another through conductive metal strip 534. [0005] As depicted in Fig. 12, movable contact assembly 524 is in a first, steady-state position, which enables current to flow (i.e., electrical communication) from first contact pad 514 through movable contact 524 into second contact pad 516 so as to activate the function controlled by second contact pad 516. As movable contact assembly 524 moves along a path that is substantially parallel to the direction of arrow B, movable contact heads 526, 528 move to positions wherein electrical communication is terminated between first contact pad 514 and second contact pad 516, and wherein electrical communication may be initiated between first contact pad 514 and third contact pad 518 or fourth contact pad 520. Similarly, movable contact assembly 524 may also move along a path parallel to arrow A. In this manner, movement of contact assembly 524 may facilitate activation or deactivation of functions associated with each of the contact pads 516, 518, and 520. [0006] Electrical communication is often initiated between a cylindrically shaped movable contact head and a flat stationary contact pad by pressing the contact head onto the stationary contact pad defining a set of locations, at which electrical communication between the contacts (i.e., current flow) occurs. Upon operation of the switch, electrical communication is terminated by movement of the movable contact head past the edge of the stationary contact pad. [0007] Under specific voltage and current conditions, an arc may be initiated as the physical distance (i.e., gap) between the contacts is increased. This arc generally occurs during the terminal portion of the period of electrical communication between contacts. The current flowing through the gap between contacts generates heat, resulting in temperatures that may be sufficiently high to cause arc erosion. As a consequence, some or all of the nearby insulation may be burned away. [0008] Fig. 13 illustrates an electrical schematic diagram of the switch configuration shown on Fig. 12. Fig. 14 shows a sectional view of the switch configuration shown on Fig. 12. [0009] Fig. 15 illustrates an area 546 on a conventional contact pad, in which arcing may occur (i.e., an arcing zone). During the life of the switch, arc erosion causes debris fields 548, including both conductive and insulating material, to form and grow on the stationary contact pads and insulating regions. [0010] Sliding movement of the contact head through the debris field may also cause debris particles to be dragged into a primary, or steady-state, area of close proximity between the contacts, known as a contacting zone 542. The accumulation of such debris (e.g., on the stationary contact pad 520) may cause increased resistance between the contacts when the contact head electrically communicates with the contacting zone on the stationary contact pad during steady-state use of the switch. Ultimately, a switch becomes non-functional, or fails, when such debris causes the electrical resistance between contacts to increase to a level, at which the circuit may no longer be effectively completed, or at which resistance in the circuit becomes unacceptably high - even though the contacts may have been placed in a position intended to enable electrical communication (i.e., a flow of current). Fig. 16 graphically illustrates voltage drop across contacts as a function of switching cycles of a conventional switch. In the illustrated example, voltage differential begins to increase and become unstable after about 25 arcing cycles. [0011] During switch operation, as a contact head is translated from one contact pad to another, debris particles may be dragged onto insulating material that is positioned between stationary contact pads. Such debris on the insulation material may reduce the dielectric strength of the insulation. Accordingly, the switch may fail when the isolation resistance between the contact pads is reduced until a short-circuit is established between contact pads. Lubrication of the contacts generally increases the rate at which debris is deposited onto the insulation. [0012] As electrical performance requirements for sliding switches continue to increase, improvement in sliding switch performance is needed to satisfy increasingly stringent requirements.

SUMMARY OF THE INVENTION [0013] The present invention provides contact structures for a sliding switch capable of extending the service life of the switch while maintaining voltage stability relative to switches having a conventional contact structure. [0014] In accordance with a first aspect of the present invention, an improved contact structure is provided for a sliding switch having a stationary contact pad and a movable contact that is capable of directing accumulation of arcing debris away from a portion of a steady-state contacting zone on the stationary contact pad. Consequently, a portion of the contacting area between stationary and movable contacts remains generally free of arcing erosion debris for an increased number of switching cycles, thus extending the service life and improving voltage stability as compared to a conventional switch contact configuration. [0015] In accordance with the first aspect of the present invention, a contact structure for a sliding switch includes a stationary contact pad and a movable contact that translates along a path extending between a current-inhibiting position and a current-permitting position. It should be understood that a current-inhibiting position is a position wherein the movable contact is electrically isolated from the stationary contact pad. Similarly, a current-permitting position is a position wherein the movable contact may maintain a primary electrical interface with the stationary contact pad. The stationary contact pad includes a contacting zone that initiates electrical communication with the movable contact when the movable contact approaches the current-permitting position. The stationary contact also includes an arcing zone that serves to terminate electrical communication with the movable contact when the movable contact moves from the current-permitting position to the current-inhibiting position. Similarly, the arcing zone may serve to initiate electrical communication with the movable contact moves from a current-inhibiting position to a current-permitting position. The arcing zone accomplishes this termination and/or initiation of electrical communication by providing an auxiliary area, at which arcing is induced to occur (i.e., is facilitated and/or preferentially encouraged) between the stationary contact and the movable contact. In an exemplary embodiment, the stationary contact and the movable contact may be shaped and configured such that when the contacting zone is projected, in parallel with respect to the path onto the arcing zone, at least a portion of a projection of the contacting zone lies outside the arcing zone so as to provide a region within the contacting zone that lies generally outside of any arcing erosion debris path created by the movable contact as the movable contact moves relative to the stationary contact. [0016] In a preferred embodiment of a sliding switch including a movable contact and a flat stationary contact pad, a contact edge is defined on the stationary contact pad such that the contact edge electrically contacts the movable contact as the movable contact moves between a current-inhibiting position and a steady-state contact position. In accordance with this embodiment, the movable contact may include a cylindrical contact head, and the flat stationary contact pad may include a V-shaped contact edge configured to partially define a region of concavity on the stationary contact pad. Consequently, this embodiment provides two arcing zones as well as a substantially arc-free region situated between the two arcing zones. In accordance with this embodiment, a portion of a contacting zone projected along a path of movement of the movable contact head falls on the substantially arc free region. A portion of the contacting zone, therefore, lies generally outside of an arcing erosion debris path created by the movable contact as it moves relative to the stationary contact. Other contact configurations may be used so that at least a portion of a projection of the contacting zone lies outside the arcing zone to provide a region within the contacting zone that lies generally outside of an arcing erosion debris path created by the movable contact as it translates relative to (e.g., slides or rolls across) the stationary contact. [0017] In accordance with a second aspect of the present invention, a contact configuration is configured to direct arcing toward a contact pad that is electrically coupled to the positive terminal of a power source. Consequently, arcing is directed away from those contact pads that are coupled to a negative terminal. This configuration is advantageous because accumulation of conductive arcing debris between adjacent stationary contact pads is reduced relative to configurations known in the art. Thus, dielectric strength between adjacent contact pads may be preserved over an extended portion of the service life of a switch. [0018] Further in accordance with the second aspect of the present invention, a contact configuration for a sliding switch includes a first stationary contact pad electrically coupled to a positive terminal of a power source, a second stationary contact pad electrically coupled to a negative terminal, and a movable contact. This exemplary embodiment also includes an insulating region that electrically isolates each of the contact pads, and the movable contact is configured to be movable between a current-permitting (i.e., contact) position, in which the movable contact electrically couples the first and second stationary contact pads, and a current-inhibiting position, in which the movable contact is electrically isolated from the second stationary contact pad. In accordance with this exemplary embodiment, the first stationary contact pad and the movable contact are configured so that, as the movable contact moves from the current-permitting position to the current-inhibiting position, the movable contact terminates electrical communication with second stationary contact pad before it terminates electrical communication with the first stationary contact pad. In addition, as the movable contact moves from the current-inhibiting position to the current- permitting position, the movable contact initiates electrical communication with the first stationary contact pad before it initiates electrical communication with the second stationary contact pad. [0019] In accordance with a third aspect of the present invention, a contact configuration facilitates simultaneous arcing at both a contact pad connected to a negative terminal as well as a contact pad connected to a positive terminal. Consequently, arcing energy is distributed among the dual contact pads, and an improvement (i.e., reduction) is realized in the formation of arcing erosion debris at the contact pad that is coupled to the negative terminal relative to the quantity of debris typically experienced in prior art structures. [0020] Further in accordance with the third aspect of the present invention, a contact configuration for a sliding switch includes a first stationary contact pad electrically coupled with a positive terminal of a power source, a second stationary contact pad electrically coupled with a negative terminal, and a movable contact. This exemplary embodiment also includes an insulating region electrically isolating each of the contact pads. In this embodiment, the movable contact is configured to be movable between a contact position, in which the movable contact electrically couples the first and second stationary contact pads, and a current-inhibiting position, in which movable contact is electrically isolated from the second stationary contact pad. The first stationary contact pad and movable contact are configured so that, as the movable contact moves from the contact position to the current-inhibiting position, the movable contact terminates electrical communication with second stationary contact pad at the same moment that it terminates electrical communication with the first stationary contact pad. As the movable contact moves from a current-inhibiting position to a current-permitting position, the movable contact initiates electrical communication with the first stationary contact pad at the same moment that electrical communication is initiated with the second stationary contact pad.

BRIEF DESCRIPTION OF THE DRAWINGS [0022] The above-mentioned features of the present invention may be more clearly understood from the following detailed description' considered in conjunction with the following drawings, in which like numerals represent like elements and in which: [0023] Fig. 1 is a plan view of a first exemplary embodiment of a contact structure in accordance with the present invention; [0024] Fig. 2 is a sectional view of the contact structure shown on Fig. 2; [0025] Fig. 3 is a plan view of a second exemplary embodiment of a contact structure in accordance with the present invention; [0026] Fig. 4 is a plan view of a third exemplary embodiment of a contact structure in accordance with the present invention; [0027] Fig. 5 is a plan view illustrating an aspect of the present invention; [0028] Fig. 6 is a graph depicting contact voltage between a movable contact head and stationary contact as a function of switching cycles for an exemplary embodiment of a contact configuration of the present invention; [0029] Fig. 7 is a plan view illustrating an aspect of an alternate embodiment of the present invention; [0030] Fig. 8 is a plan view illustrating an aspect of a second alternate embodiment of the present invention; [0031] Fig. 9 is a plan view illustrating an aspect of a third alternate embodiment of the present invention; [0032] Fig. 10 is a plan view illustrating an aspect of a fourth alternate embodiment of the present invention; [0033] Fig. 11 is a section view of the an aspect of the fourth alternate embodiment of the present invention; and [0034] Fig. 12 is a plan view of a contact structure known in the prior art; [0035] Fig. 13 is an electrical schematic of the contact structure shown on Fig. 12; [0036] Fig. 14 is a sectional view of a prior art contact structure; [0037] Fig. 15 is a plan view illustrating an aspect of a prior art contact structure; and [0038] Fig. 16 is a graph depicting an aspect of a prior art contact structure.

DETAILED DESCRIPTION OF THE INVENTION [0039] As discussed above, contact configurations in accordance with the present invention are capable of providing an increased number of switching cycles while providing a more stable resistance across contacts than achieved by known contact configurations. [0040] Referring to the figures, Figs. 1-2 illustrate a first exemplary embodiment of a contact configuration 110 for a sliding switch. [0041] Circuit board substrate 112 is formed of a synthetic resin of an insulating material. First conductive stationary contact pad 114, which is electrically coupled to a positive terminal of a power source, is disposed on substrate 112. Second, third, and fourth conductive stationary contact pads 116, 118, 120, connected to a negative terminal of a power source via a ground connection, are also disposed on substrate 112. Insulating material 122, such as a solder mask, is disposed between contact pads 114, 116, 118, 120. [0042] Conductive movable contact assembly 124 is mounted to an un-illustrated holder, which permits movement in the directions indicated by arrows A and B. In an exemplary embodiment, movable contact assembly 124 includes first and second cylindrically shaped conductive movable contacts 126, 128, mounted to respective conductive contact springs 130, 132. Contact springs 130, 132 are electrically coupled to one another by a conductive metal strip 134. As shown on Fig. 1, second movable contact 128 maintains electrical communication with respective stationary contact pads 116, 118, 120 generally at a contact line 128a, in which cylindrically shaped second movable contact 128 contacts respective contact pad 116, 118, 120. [0043] As shown on Fig. 1, movable contact assembly 124 is in a first steady-state position, which enables current to flow from first contact pad 114 through movable contact assembly 124 into second contact pad 116 so as to activate a function controlled by second contact pad 116. As movable contact assembly 124 moves along a path in parallel with the direction of arrow B, movable contacts 126, 128 move to a second steady-state position (illustrated in phantom at 136a, 136b, respectively) that represents a first OFF position. In an exemplary embodiment, movable contact assembly 124 may continue to move in the direction of arrow B to a third steady-state position (illustrated by contacting zones shown in phantom at 138a, 138b), in which a function controlled by third contact pad 118 is activated, to a fourth steady-state position (illustrated in phantom at 140a, 140b, respectively) that represents a second OFF position, and to a fifth steady-state position (illustrated by contacting zones shown in phantom at 142a, 142b, respectively), at which a function controlled by fourth contact pad 120 is activated. Similarly, movable contact assembly 124 may translate from fifth steady-state position along a path in parallel with arrow A to other steady-state positions. [0044] As shown on Fig. 1, fourth contact pad 120 includes first and second protruding portions 144a, 144b, which provide an electrical interface for discharge of arcing as second movable contact 128 moves between fourth and fifth positions in a direction parallel with the direction of arrows A and B, thereby initiating electrical communication with, or terminating electrical communication with, fourth contact pad 120. Protruding portions 144a, 144b are each at least partially defined by a peripheral edge 146 that is in non-parallel relation with contact line 128a. As shown on Fig. 1, first and second protruding portions 144a, 144b combine to form a "V shape. In accordance with this embodiment, the top of the "V functions as both first and second arcing zones 148a, 148b, respectively, and provide an electrical interface for discharge of arcing. [0045] As illustrated on Fig. 1, when contacting zone 142b is projected along movement path (indicated by arrows A and B) onto first and second arcing zones 148a, 148b, at least a portion of a projection 150 of contacting zone 142b lies outside arcing zones 148a, 148b, thereby providing a region 152 within contacting zone 142b that is generally outside of an arcing erosion debris path (648a, 648b as shown on Fig. 5) created by second movable contact 128 as it translates (e.g., slides, rolls) across fourth contact pad 120. [0046] Similarly, second and third contact pads 116, 118 include protruding portions that also provide an electrical interface for discharge of arcing. [0047] Fig. 5 shows a movable contact 628 and a stationary contact pad 620 similar to second movable contact 128 and fourth stationary contact pad 120 as shown on Figs. 1 and 2. Fig. 5 illustrates two arcing zones 646a, 646b, that provide an electrical interface, at which arcing occurs on stationary contact pad 620 as movable contact head 628 moves so as to initiate electrical communication with stationary contact pad 620 (e.g., as movable contact head 128 translates between fourth and fifth steady-state positions 140a, 142a, as depicted on Fig. 1). It should be appreciated that arcing erosion debris fields 648a, 648b, including both conductive and insulating material, are likely to form and accumulate on stationary contact pad 620 and insulating material 622 during the service life of switch. Debris fields 648a, 648b generally spread from arcing zones 646a, 646b in parallel with the direction of a path of movement of contact head 628 in the direction of arrows A and B. Consequently, arcing zones 646a, 646b are positioned so that a portion 650 of contacting zone 642a generally remains outside of arcing erosion debris fields 648a, 648b over an extended portion of the service life of switch. As a result, as shown on Fig. 6, contact voltage differential between movable contact 628 and stationary contact pad 620 remains relatively low, and stable, over an extended portion of the service life of switch. This is a significant improvement over the performance, as shown by graph 702 on Fig. 16, of contact configurations of switches lαiown in the prior art. [0048] Fig. 3 illustrates a second contact arrangement 310 for a sliding switch. Similar to arrangement 110 depicted in Fig. 1, second contact arrangement 310 includes second, third, and fourth conductive stationary contact pads 316, 318, 320, which are disposed on substrate 312 and electrically coupled to a negative terminal of a power source via a ground connection. Second contact arrangement 310 further includes a conductive movable contact assembly 324 including first and second cylindrical, conductive, movable contacts 326, 328. In accordance with this embodiment, first stationary contact pad 314, which is connected to a positive terminal of a power source, includes first, second, and third conductive pad portions 360, 362, 364. A first insulating region 366 is disposed between first and second pad portions 360, 362. A second insulation region 368 is disposed between second and third pad portions 362, 364. [0049] Second contact arrangement 310 is configured such that, as the switch moves from an ON position to an OFF position, first movable contact 326 initially terminates electrical communication with first stationary contact pad 314 before terminating electrical communication with one of second, third, or fourth contact pads 316, 318, 320. Second contact arrangement 310 is also configured such that as the switch moves from an OFF position to an ON position, second movable contact 328 initiates electrical communication with one of second, third, or fourth contact pads 316, 318, 320 before first movable contact 326 initiates electrical communication with first stationary contact pad 314. Consequently, arcing occurs between first movable contact 326 and first stationary contact pad 314 and does not occur for a significant portion of the service life of switch between second movable contact 328 and second, third, and fourth stationary contacts pads 316, 318, 320. This is advantageous in that formation of conductive arc debris between second, third, and fourth stationary contact pads 316, 318, 320 is prevented or minimized. One skilled in the art will appreciate that it is advantageous to minimize such arc debris, which tends to reduce dielectric strength between adjacent pads and sometimes causes a conductive circuit to form between pads. Protruding portions 344a, 344b are illustrated on second portion 362 of first stationary contact pad 314. Arcing is facilitated and/or encouraged, and generally occurs, at the protruding portions 344a, 344b generally within path 370. [0050] Fig. 4 illustrates a third contact arrangement 410 for a sliding switch. Third contact arrangement 410 is similar to arrangement 310, depicted in Fig. 3, and includes a first stationary contact power pad 414 that is electrically coupled to a positive terminal of a power source. First stationary contact power pad 414 includes first, second, and third conductive pad portions 460, 462, 464. First insulating region 466 is disposed between first and second pad portions 460, 462, and second insulation region 468 is disposed between second and third pad portions 462, 464. Third insulating region 480 exists between first and second stationary contact pads 416, 418, and a fourth insulation arrangement 482 exists between second and third stationary contact pads 418, 420. [0051] Third contact arrangement 410 is configured such that, as the switch moves from an ON position to an OFF position, a first movable contact 426 terminates electrical communication with first stationary contact pad 414 simultaneously with the termination, by second movable contact 428, of electrical communication with one of second, third, or fourth contact pads 416, 418, 420. Second contact arrangement 410 is also configured such that, as the switch moves from an OFF position to an ON position, second movable contact 428 initiates electrical communication with one of second, third, or fourth contact pads 416, 418, 420 at the same moment that first movable contact 426 initiates electrical communication with first stationary contact pad 414. Consequently, arcing occurs with both the first and second movable contacts 426, 428. This configuration is capable of decreasing formation of arcing erosion debris at the contact pads connected to the negative terminal relative to the amount of debris typically generated by configurations known in the prior art. [0052] Fig. 7 depicts a first alternate contact pad configuration 710 in accordance with the present invention, wherein a stationary contact pad 720 and a movable contact 728 are mutually shaped and configured such that at least a portion 750 of a contacting zone 742a lies outside an arcing zone 746a when contacting zone 742a is projected along a path of movement of contact head 728, as depicted by arrows A and B. Therefore, a region 750 is provided within contacting zone 742a, which lies generally outside arcing erosion debris path 748a created by movable contact 728 as it translates relative to (e.g., slides or rolls across) stationary contact pad 720. Fig. 7 illustrates a protruding portion 744a, a receiving edge 760, and a line of contact 762 of movable contact 728. It should be noted that the line of contact 762 and the receiving edge 760 are in non-parallel relation with respect to one another. [0053] Fig. 8 depicts a second alternate contact pad configuration 810 in accordance with the present invention, wherein a stationary contact pad 820 and a movable contact 828 are mutually shaped and configured such that at least a portion 850 of a contacting zone 842a lies outside an arcing zone 846a when contacting zone 842a is projected along a path of movement of contact head 828 as depicted by arrows A and B. Therefore, a region 850 is provided within contacting zone 842a, which is generally outside arcing erosion debris path 848a created by movable contact 828 as it translates relative to (e.g., slides or rolls across) stationary contact pad 820. A receiving edge 860 is shown in non-parallel relation to movable contact 862. [0054] Fig. 9 depicts a third alternate contact configuration 910 in accordance with the present invention. A conventional stationary contact pad 920 is rectangular in shape, and movable contact 928 includes first and second projecting portions 928a, 928b. Stationary contact pad 920 and movable contact 928 are mutually shaped and configured such that at least a portion 950 a contacting zone 942a lies outside an arcing zone 946a, 946b when contacting zone 942a is projected along a path of movement of movable contact 928, as depicted by arrows A and B. In accordance with this embodiment, a region 950 is provided within contacting zone 942a, which lies generally outside arcing erosion debris path 948a, 948b created by movable contact 928 as it translates relative to stationary contact pad 920. [0055] Figs. 10 and 11 depict a fourth alternate contact configuration 1010 in accordance with the present invention. A stationary contact pad 1020 is rectangular shaped, and movable contact 1028 includes first, second, and third furcations 1028a, 1028b, 1028c. Stationary contact pad 1020 and movable contact head 1028 are mutually shaped and configured such that at least a portion 1052b, c of contacting zone 1052a, 1052b, 1052c lies outside an arcing zone 1048 when contacting zone 1052a, 1052b, 1052c is projected along a path of movement of movable contact 1028, as depicted by arrows A and B. [0056] It should be appreciated that the preferred embodiments shown and described herein are provided merely by way of example and are not intended to limit the scope of the invention in any way. Preferred dimensions, ratios, materials and construction techniques are illustrative only and are not necessarily required to practice the invention. It is intended that the scope of the present invention herein disclosed should not be limited by the particular disclosed embodiments herein. Further modifications and alterations may occur to others upon reading and understanding the specification.

Claims

Claims:

What is claimed is:

Claim 1: A contact structure for a sliding switch, comprising: a first, conductive, stationary contact (120) disposed on a base (112); a conductive, movable contact (124) for electrically contacting said stationary contact (120), said movable contact (124) being movable relative to said stationary contact (120) along a path (A, B) from a current-permitting position, in which said movable contact (124) maintains a primary electrical interface with said stationary contact (120), to a current- inhibiting position, in which said movable contact (124) is electrically isolated from said stationary contact (120); a contacting zone (142a, 142b) defined on said stationary contact (120), said contacting zone (142a, 142b) electrically contacting said movable contact (124) when said movable contact (124) occupies said current-permitting position; and an arcing zone (148a, 148b) defined on at least one of said stationary contact (120) or said movable contact (124), said arcing zone (148a, 148b) configured to provide an electrical interface, in which arcing occurs between said stationary contact (120) and said movable contact (124).

Claim 2: A contact structure for a sliding switch as recited in claim 1, said arcing zone (148a, 148b) configured to initiate electrical communication with the other of said stationary contact (12) or said movable contact (124) when said movable contact (124) traverses said path (A, B) in a direction from said current-inhibiting position to said current- permitting position. Claim 3: A contact structure for a sliding switch as recited in claim 1, said arcing zone (148a, 148b) configured to terminate electrical communication with the other of said stationary contact (120) or said movable contact (124) when said movable contact (124) traverses said path (A, B) in a direction from said current-permitting position to said current-inhibiting position.

Claim 4: A contact structure for a sliding switch as recited in claim 1, wherein said stationary contact (120) is a flat pad.

Claim 5: A contact structure for a sliding switch as recited in claim 2, wherein said movable contact (124) is shaped substantially as a cylinder.

Claim 6: A contact structure for a sliding switch as recited in claim 5, wherein a central axis of said movable contact (124) is perpendicular to said path (A, B).

Claim 7: A contact structure for a sliding switch as recited in claim 1, wherein said arcing zone comprises a protruding region (144a).

Claim 8: A contact structure for a sliding switch as recited in claim 1, said stationary contact (120) and said movable contact (124) being mutually shaped and oriented such that at least a portion of a projection (150) of said contacting zone (142a, 142b) along said path (A, B) onto said arcing zone (148a, 148b) lies outside said arcing zone (148a, 148b), thereby providing a region (52) within said contacting zone (142a, 142b), said region (52) being positioned generally outside of an arcing erosion debris path (648a, 648b) created by said movable contact (124) as said movable contact (124) moves along said path (A, B).

Claim 9: A contact structure for a sliding switch as recited in claim 1, further comprising a second, conductive, stationary contact (414) disposed on said base (112); wherein said movable contact (426, 428) is configured for electrically connecting said first stationary contact (420) and said second stationary contact (414), said movable contact (426, 428) being movable along a path from a current facilitating position, in which said movable contact (426, 428) facilitates electrical communication between said first stationary contact (420) and said second stationary contact (414), to a current-inhibiting position, in which said first stationary contact (420) and said second stationary contact (414) are electrically isolated from one another, said movable contact (426, 428) being configured to simultaneously terminate electrical communication with both of said first stationary contact (420) and said second stationary contact (414) as said movable contact (426, 428) moves from said current-permitting position to said current-inhibiting position.

Claim 10: A contact structure for a sliding switch as recited in claim 1, further comprising: a second conductive, stationary contact (318) disposed on said base (312), said first stationary contact (320) and said second stationary contact (318) of a first electrical polarity; a third conductive, stationary contact (314) disposed on said base (312), said third stationary contact (314) of a second polarity opposite said first polarity, said third stationary contact (314) including a first conductive portion (364) and a second conductive portion (362); an insulator (368) disposed so as to electrically isolate said first stationary contact (320), said second stationary contact (318), said third stationary contact (314), said first conductive portion (360) and said second conductive portion (362); said movable contact (324) configured to move along a path (A, B) from a first contact position, in which said movable contact (324) communicates electrically with said first stationary contact (320) and said first conductive portion (364), to a second contact position, in which said movable contact (324) communicates electrically with said second stationary contact (318) and said second conductive portion (362); said path including a current-inhibiting position located between said first contact position and said second contact position; said first stationary contact (320) and said first conductive portion (364) being electrically isolated from one another, and said second stationary contact (318) and said second conductive portion (362) being electrically isolated from one another, when said movable contact (324) is in said current-inhibiting position; and said movable contact (324) being configured to terminate electrical communication with said first conductive portion (364) before said movable contact (324) terminates electrical communication with said first stationary contact (320) as said movable contact (324) moves from said first contact position toward said current-inhibiting position, thereby directing discharge of arcing to said third stationary contact (314) and preventing degradation of insulation performance between said first stationary contact (320) and said second stationary contact (318).

Claim 11: A method of preventing degradation in performance of a sliding switch comprising the steps of: providing a first, conductive, stationary contact disposed on a base, said stationary contact including a contacting zone; providing a conductive contact movable relative to said contacting zone along a path from a current-permitting position, in which said movable contact maintains a primary electrical interface with said contacting zone, to a current-inhibiting position, in which said movable contact is electrically isolated from said stationary contact, said movable contact configured for electrically contacting said contacting zone when said movable contact is in said current-permitting position; and providing an arcing zone defined on at least one of said stationary contact or said movable contact, said arcing zone configured to provide an electrical interface, in which arcing occurs between said stationary contact and said movable contact; whereby arcing is encouraged to occur outside said path upon engagement or disengagement between said conductive, moveable contact and said stationary contact.