Metal working – Method of mechanical manufacture – Electrical device making
Reexamination Certificate
1998-02-12
2001-03-27
Young, Lee (Department: 3729)
Metal working
Method of mechanical manufacture
Electrical device making
C029S756000, C029S884000, C200S0050EA
Reexamination Certificate
active
06205650
ABSTRACT:
The present invention relates to a method of producing an electrical switch comprising a housing at least partially enclosing switching means for cooperating with a set of at least two metallic terminals, each terminal having an exterior portion outside the housing and an interior portion inside the housing.
In relation to switches of this type it is extremely important to reduce the manufacturing costs. Any factor that increases the number of switches produced in a given period of time with the same personnel, factory space and discrete units of production equipment is essential for the competitiveness of the finished switch in the marketplace.
It is therefore an object of the present invention to provide a method of producing such switches in which such an increased production capacity is obtained as compared with prior art methods.
A method for producing keyboard switches is known from European Patent No. 0 329 968 in which a single row of sets of metallic terminals is punched out of a strip of the base metal of the terminals, a housing is moulded around each set of terminals, switching means are installed in each housing and each set of terminals is thereafter separated from the strip. In this method the necessary moulding and installing operations are confined to a single production track defined by the single row of sets in the strip.
A method for producing push button switches is known from U.S. Pat. No. 4,803,316 in which two parallel rows of sets of terminals are punched out of a strip, and a housing frame is moulded on each set whereafter the sets are separated from the strip and processed individually for installing the switching means. In this method the individual processing of each discrete set of terminals with attached housing frame requires a number of additional handling steps for insertion in, guidance through, removal from and transportation between the various work stations corresponding to the subsequent steps of installing the switching means in each individual and discrete housing frame.
So as to be able to form the sets, attach the housings to the sets, install the switching means in the housings and finally separate the sets from the sheet all in more than one product ion track while the sets still are interconnected in the sheet, the method according to the invention comprises:
providing a substantially planar sheet of the base metal of said terminals,
removing port ions of the sheet so as to form within the boundaries thereof at least two rows of said sets of metallic terminals and so that each terminal remains attached to the sheet solely at the end of the exterior portion of each terminal farthest from the interior portion thereof,
attaching a housing to each of the sets in the sheet,
installing a switching means in each of the housings, and
separating said end of each of the exterior portions of each set provided with a housing and a switching means from the sheet.
Preferably, a housing is attached to each of one or more sets in each of all the rows substantially simultaneously, and a switching means is subsequently installed in each of the housings in one or more steps, each of said steps being performed in one or more housings of each of all the rows substantially simultaneously.
When the housings consist of a mouldable plastic material, the housings are preferably attached to each set by being moulded around the metallic terminals of the set.
So as to utilize the material of the sheet of base metal as efficiently as possible, the sets are preferably disposed in the sheet in an array constituted by substantially parallel, rectilinear rows of sets extending in a first direction and by further substantially parallel, rectilinear rows of sets extending in a second direction substantially at right angles to the first direction.
Preferably, apertures for guiding and positioning the sheet during the steps of attaching the housing, installing the switching means and separating the sets from the sheet are provided along the edges of the sheet and in at least some of the regions between the sets.
In cases where the same switch can be used for two or more applications it is advantageous that the same production method and equipment can be used for manufacturing the switch for all such applications and therefore according to the invention each set of terminals may comprise at least two sub-sets, each sub-set corresponding to a different application of the switch, the method comprising a further step in which at least a portion adjacent said end of the exterior portion of each of the terminals of the sub-set or sub-sets of each set not relevant for the current application of the switch is separated from the rest of the terminal and thereby from the completed switch.
The method of production according to the invention can advantageously be used for a variety of different switches such as rotary switches, toggle switches, on-off switches etc. The method is particularly advantageous in connection with keyboard switches. A currently very utilized keyboard switch is square and has outer dimensions of 6 mm by 6 mm, and the free ends of the terminals of such a switch correspond to the connection points of printed circuit boards designed for such switches. To create more room for other components connected to the printed circuit board it is advantageous that the keyboard switch have smaller dimensions, for instance 4 mm by 4 mm. To enable his smaller switch to be used both with printed circuit boards designed for the larger switches and with printed circuit boards designed for the smaller ones, the housing of the keyboard switch has, according to the invention, a square section in a plane parallel to the plane of the sheet, the exterior dimensions of the square section being 4 mm wide and 4 mm long, and the set of terminals comprising a first sub-set corresponding to an application, for example exterior printed circuit board electrical connections, of a keyboard switch with a square section with exterior dimensions of 6 mm by 6 mm, and a second sub-set corresponding to an application, for example exterior printed circuit board circuit connections, of a keyboard switch with a square section with exterior dimensions of 4 mm by 4 mm.
To further reduce production time and thereby increase the throughput with given means as regards personnel, space and production units it is advantageous to reduce the number of separate elements in the switching means, and therefore it is advantageous to apply the method according to the invention to a keyboard switch wherein the switching means of the keyboard switch comprise a contact element for electrically interconnecting at least two of the terminals in a first position of said contact element and interrupting said electrical interconnection in a second position, an activating element for moving the contact element from its second to its first position, a resiliently deformable member arranged for cooperation with the activating element such that it is resiliently deformed when the contact element is in its first position and is undeformed when the contact element is in its second position, and a key element connected to the activating element, said key element being arranged for being operated by a fingertip of a user of the keyboard, the activating element, the deformable member and the key element constituting an integral unit made from a resiliently deformable material such as silicone rubber.
To further reduce the number of steps to be performed during the installation of the switching means, the contact element, prior to installing the switching means in the housing, is preferably fixedly attached to said unit, for instance by partially embedding it in the material of the unit.
Preferably, the sheet of base metal is substantially rectangular, the rows of sets of terminals being substantially parallel to the sides of the rectangle.
In some applications it is advantageous that the sheet constitutes a strip that can be wound on and off a roll.
The invention further relates to an electrical switch produced by a method accordin
Enoch Claus
Jacobsen Flemming
MEC A/S
Tugbang A. Dexter
Young Lee
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