Patent 3646300 - CONTACT SWITCH
|United States Patent||Patent Number 3,646,300|
|Manabe||Issued February 29, 1972|
|**Please see images for: ( Certificate of Correction ) **|
An electrical switch having fixed contacts with which a movable contact is adapted to selectively engage as the switch is actuated. The movable contact is so constructed and so mounted in a recess in a carrier therefor that misalignment or tilting of the carrier will not significantly affect engagement between the contacts.
|Inventors:||Noboru Manabe (Tokyo JA)|
|Assignee:||Alps Electric Co., Ltd. (Tokyo, JA)|
|Filed:||April 9, 1970|
|Nov 19, 1969 [JA]||44/109811|
|Current U.S. Class:||200/16A - 200/16R - 200/258 - 200/275|
|Current CPC Class:||H01H 13/562 (20130101)|
|Current International Class:||H01H013/56 (20060101)|
|Field of Search:||;200/16R,16A,166D,166BH,166H|
|3546402||December 1970||Spaeth et al.|
|3352980||November 1967||De Rougemont et al.|
|3259728||July 1966||De Rougemont et al.|
|2762880||September 1956||Hathorn et al.|
1. A contact switch comprising a casing with an inner chamber, contacts on the inner wall of said casing and exposed to said chamber, a carrier member movable in said chamber, there being clearance between said carrier between said carrier member and said casing, said carrier member having a recess with a wall facing said contacts, a contact member in said recess, said contact member having an inner wall and a pair of outer walls resiliently connected to and normally spaced from said inner wall on opposite sides thereof respectively, the second of said outer walls extending outwardly from said recess toward said inner wall of said casing and engaging and sliding over said contacts, the first of said outer walls having a protrusion with surface extending toward and rockingly engaging said recess wall around an axis in the direction of movement of said carrier member, whereby upon tilting of said carrier member in said chamber about an axis along its direction of movement said protrusion remains in rocking engagement with said recess wall, thereby maintaining said second outer wall in engagement with said contacts under substantially uniform pressure.
2. A contact switch as recited in claim 1, wherein said second outer wall is divided into separate contacting surfaces individually engageable with said contacts.
3. A contact switch as recited in claim 1, wherein said second outer wall comprises a vertical channel dividing said second outer wall into separate contacting surfaces individually engageable with said contacts.
4. A contact switch as recited in claim 1, wherein said first outer wall is divided into separate surfaces each having a protrusion thereon extending toward and engaging said recess wall, thereby aligning said contact member in said recess, whereby said second outer wall remains engaged with said contacts under uniform pressure.
5. A contact switch as recited in claim 3, wherein there is an opening in said first outer wall dividing said outer wall into separate surfaces each having a protrusion thereon extending toward and engaging said recess wall, thereby aligning said contact member in said recess, whereby said second outer wall remains engaged to said contacts.
6. A contact switch as recited in claim 1, wherein said recess comprises sidewalls within said recess and vertically disposed to said recess wall, said first outer wall comprising flaps at each end thereof and vertically disposed to said first outer wall, and which are contactable by said sidewalls such that upon forward thrust of said carrier member, a first flap contacts a first side wall whereby said contact member is likewise thrust forward, and such that upon reverse thrust by said carrier member, a second flap contacts said second sidewalls, whereby said contact member is likewise thrust reversely.
7. A contact switch as recited in claim 5, wherein said protrusions on said first outer wall are in registration with said contacting surfaces in a direction transverse to the direction of movement of said carrier member, whereby said contacting surfaces remain engaged with said contacts under uniform pressure.
8. A contact switch as recited in claim 1, wherein said recess wall is substantially flat and said protrusion surface is convexly curved thereby to define substantially a point contact with said flat recess wall.
9. A contact switch as recited in claim 1, wherein said contact member is generally S-shaped.
The present invention relates to an improved contact switch, and more particularly, a contact switch which maintains proper electrical contact at all times, and in which switching noise is minimized.
A conventional slide switch has a sliding contact mounted in a recess in a movable member or carrier, that sliding contact selectively engaging fixed contacts as the movable member is shifted, thereby to modify the electrical circuit through the switch. Those movable contacts have generally been in the form of a spherical projection which produces only a point contact with fixed contacts on the inner walls of a surrounding casing. As a result, switches of this type have been subject to considerable wear through the abrasive action of the spherical projection sliding over the fixed contact surfaces. Over a period of time, such switches become rather noisy in operation, but more important, the high degree of wear leads to unstable electrical contact. Hence this type of switch becomes unreliable in operation after an extended period of time.
It is a prime object of the present invention to provide a contact switch which eliminates the above discussed disadvantages in the prior art, and does so by means of an inexpensive, simple and sturdy structure.
It is a more specific object of the present invention to provide a contact switch which initiates and maintains reliable electrical contact even after long periods of use.
It is another object of the present invention to provide a contact switch the operation of which is essentially unaffected by abrasive wear on the contact surfaces.
It is a further object of the present invention to provide a contact switch which produces a minimum amount of electrical noise, and which does not require an excessive amount of pressure for actuation.
A switch casing is provided which, as is conventional, has an inner chamber where fixed contacts are exposed. A movable member or carrier is shiftable within that chamber, and it carries a movable contact adapted selectively to engage the fixed contacts as the movable member is shifted, thereby to modify the electrical circuit through the switch. In accordance with the present invention that movable member is provided with a recess within which a first wall of the movable contact is received and from which a second wall of the movable contact extends, that movable contact being resilient and being compressed between an innerwall of the recess (engaged by said first contact wall) and the fixed contacts (engaged by said second contact wall). The first contact wall is provided with protrusions which engage said inner recess wall, thus permitting relative movement between movable member and movable contact without adversely affecting the engagement between said second contact wall and said fixed contacts. Preferably the later engagement is a surface engagement, and the protrusions on said first contact wall are in registration with the surface engagement areas of said second contact wall.
To the accomplishment of the above, and to such other objects as may hereinafter appear, the present invention relates to the construction of a contact switch as defined in the appended claims and as described in the specification taken together with the accompanying drawings in which:
FIG. 1 is a top plan view, partially cross sectioned, of the contact switch mechanism of the present invention;
FIG. 2 is a cross-sectional view taken along the line 2--2 of FIG. 1; and showing the movable carrier member in a normal position;
FIG. 3 is an enlarged three-quarter perspective view of the contact member; and
FIG. 4 is a view similar to FIG. 2 but showing the movable carrier member in various positions tilted with respect to its normal position.
Referring to the drawing, FIG. 1 illustrates the contact switch generally designated by the numeral 10. The casing 12 is generally rectangular in section and is bounded by the inner walls 14, those walls defining an inner chamber 21 open at its ends. Fixed to these inner walls 14 are two sets of electrical contacts 16a, 16b and 16c, which extend throughout the entire height of the casing 12, and which may, as shown, protrude through and beyond the boundaries of the outer walls 15 of the casing 12. The contacts 16a, 16b and 16c are shown as, but need not be, equally spaced from one another.
A movable carrier member 17 is received in chamber 21, protrudes out from at least one end of the chamber and is movable within the chamber in the direction indicated by arrow 50 at least for a distance equal to the spacing between an adjacent pair of contacts (16a and 16b, or 16c and 16d). A substantial clearance 42 is provided between the movable member 17 and the inner walls 14 defining chamber 21. A recess 18 is formed in the member 17, that recess 18 facing one set of fixed contacts 16a-c. As illustrated, that recess 18 is generally rectangular in cross section, having an inner or bottom wall 20 and sidewalls 22 and is adapted to receive a contact member designed to operatively electrically selectively engage contacts 16a-16c.
FIG. 3 illustrates such a contact member generally designated 24. The embodiment shown consists basically of an intermediate or inner wall 30, a first outer wall 26, and a second outer wall 28. The outer walls 26 and 28 are disposed on opposite sides of the inner wall 30 and are substantially vertical. The outer walls 26 and 28 are connected to the inner wall 30 by means of the connecting sections 36. The combination of the first outer wall 26, a connecting section 36, and the inner wall 30, form a substantially "V" shaped channel. Likewise, the combination of the second outer wall 28, a connecting piece 36, and the inner wall 30, forms a substantially "V" shaped channel which is oppositely disposed to the first channel. The contact member 24 is resiliently compressible from one outer wall to the other, and may be formed from a single sheet of resilient conductive material. As shown best in FIGS. 2 and 4, the outer walls 26 and 28 of the contact member 24 are resiliently pressed toward the inner wall 30 by the bearing of the casing inner wall 14 and recess inner wall 20 respectively.
Preferably a pair of opposed recesses 18 are formed in the movable member 17, each with its own resilient contact member 24, thereby to provide a balanced force on the member 17 both laterally and rotationally. The second contact member 24 may, if desired, coact with the second set of fixed contacts 16a-c, and the switch is so disclosed in the drawings.
The second outer wall 28 contacts the fixed contacts 16a, 16b and 16c, located on the inner wall 14 of the casing 12. That outer wall 28 is divided into separate contacting surfaces 27a and 27b, which division is accomplished by forming a vertical channel 32 substantially in the center of the second outer wall 28. The channel 32 is bounded by the sloping walls 34, and the inner wall 35. The channel 32 provides a separation between the first outer wall sections 27a and 29b producing individual contact surfaces. Those contact surfaces are generally planar, and of substantial area. They are spaced from one another by a distance corresponding to the distance between laterally adjacent fixed contacts.
The fist outer wall 26 has a vertical, central cutout 38 through its entire height. This cutout 38 divides the first outer wall 26 into individual sections 29a and 29b, which collectively are slightly wider than the inner wall 30, and each having a protrusion 40 in the shape of a spherical segment centrally located thereon, which is capable of maintaining contact with the recess inner wall 20 even though the contact member 17 may tilt or rotate from its normal position shown in FIG. 2.
At the outer end of each section 27a and 27b of the second outer wall 28, and extending substantially throughout the entire height of that wall, are inwardly extending flaps 44a and 44b perpendicularly disposed to that wall.
Referring to FIGS. 2 and 4, the contact members 24 are shown situated in their respective recesses 18. The second outer wall 28 of each contact member is illustrated as, uniformly throughout its entire area, contacting the upstanding contacts 16a and 16b. The protrusions 40 are shown engaged with the inner wall 20 of the recess 18. Since in this position the contact member 24 is compressed, the second outer wall 28 and the first outer wall 26 are urged respectively against the upstanding contacts 16a and 16b, and the recess inner wall 20.
As shown in FIG. 4, the movable member 17 having a clearance 42 between itself and the casing inner walls 14, can be rotated or tilted about its own longitudinal axis until its corners 19 touch the casing inner walls 14, or touch the connecting piece 36 of the contact member 24. Throughout the entire allowable rotation of the contact member 17, the recess inner walls 20 remain engaged with the protrusions 40, thereby providing no appreciable change in the compression stored up in the resilient contact member 24. This causes the contact sections 27a and 27b to remain uniformly in contact with the contacts 16a, 16b and 16c, throughout the entire allowable rotation of the contact member 17. The S-shape of the contact members 24 cooperate in ensuring uniform engagement with the fixed contacts.
Referring now to FIG. 1, the movable member 17 is shown in a first position in which the contact member 24 is situated opposite the two contacts 16a and 16b. In this position the contact section 27a engages the contact 16a and the contact section 27b engages the contact 16b. When the movable member 17 is thrust forward (up in FIG. 1), the contact member 24 moves therewith, and the contact sections 27a and 27b slide along the contacts 16a and 16b, disengaging from them. Engagement of the flap 44a with a side wall 22 of recess 20 aids in causing contact member 24 to move smoothly with movable member 17. As the movable member 17 is thrust further forward the contact sections 27a and 27b respectively engage the contacts 16b and 16c. Through this entire forward movement, the protrusions 40 remain engaged to the recess inner wall 20 regardless of the fact that the movable member 17 may be rotated or tilted slightly about its longitudinal axis. Hence uniform contact engagement is ensured, and electrical noise is greatly minimized.
While but a single embodiment of the present invention is here disclosed, it will be appreciated that many variations may be made in the details thereof without departing from the spirit and scope of the invention, as defined in the appended claims.
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