Patent Publication Number: US-5158468-A

Title: Self-retaining contact assembly

Description:
TECHNICAL FIELD 
     This invention relates generally to electrical contacts in general and, more particularly, to a self-retaining electrical contact which is hand-insertable into a housing. 
     BACKGROUND 
     Most electrical contact assemblies require additional mounting structures to a housing such as rivets, screws, and other hardware, not to mention solder interconnections. In addition to the obvious increase in material and labor costs of manufacturing these contact assemblies, many require special tools to attach the contacts to the housing. Furthermore, the contact assemblies used in many products are difficult and impractical to repair. Additional mounting structures typically cause a decrease in the reliability of the contact structure. Therefore, there exists a need for a solderless contact assembly that allows for ease of assembly as well as disassembly and having a minimum of mounting structures. 
     SUMMARY OF THE INVENTION 
     An electrical contact for use in a housing having at least a first appending wall and a second appending wall comprises a contact finger substantially fitted on an inner wall of the first appending wall and on an outer wall of the second appending wall for placement in a housing aperture, the contact finger having at least a first portion, a second portion, and a third portion, the first portion protruding below the aperture and contacting a contact area on a substrate located within the housing, the second portion clipping on to opposing walls of the second appending wall and the third portion protruding from the aperture forming an external contact area. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a charger housing and electronic contact assembly in accordance with the present invention. 
     FIG. 2 is a cut view of a charger housing and electronic contact assembly in accordance with the present invention. 
     FIG. 3 is a frontal view of a charger housing and electronic contact assembly in accordance with the present invention. 
     FIG. 4 is a perspective view of the electronic contact assembly in accordance with the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring to FIG. 1 there is shown a perspective view of a charger housing and contact assembly 10 in accordance with the present invention. Preferably, the assembly 10 comprises a plastic bottom portion 26 and a plastic top portion 24 that snap together without using any special tooling or fasteners. The top portion 24 further preferably comprises a well 30 for receiving a rechargeable battery (not shown) having contacts (not shown) for mating with charger contacts 17 or contact fingers, or extending features that protrude from an aperture or opening 31 in the top housing portion 24. 
     Referring to FIG. 2, there is shown a partial cut view of the charger housing and contact assembly 10. In further detail, the assembly 10 comprises a top housing portion 24 and a bottom housing portion 26 that retains a substrate or printed circuit board 20 within the housing assembly. The printed circuit board preferably includes a wiping contact surface 22 for contacting with a hand-insertable, hand removable self-locking electrical contact 11 that inserts and attaches itself to at least one of the walls 28 of the top housing portion 24. The top housing 24 preferably comprises a first appending wall or inverted wall 29 and a second appending wall or inverted wall 28. The first wall 29 preferably includes an aperture or opening 31 and another opening 32 wherein the electrical contact 11 is hand-inserted through. Preferably, the contact 11 comprises a first portion 12 that protrudes below the aperture 32 and is biased toward a contact pad 22 on the substrate 20. The contact 11 also comprises a second portion 14 that clips or forms a press fit to opposing sides of the appending wall 28. The contact further comprises a third portion 16 that protrudes from the aperture 31 that allows a rechargeable battery having contacts (not shown) to be charged via the contact 11. The third portion 16 preferably further includes an extending feature 17 that allows for better contact with the battery contacts even if the battery contacts are slightly recessed. The second portion 14 also includes members 13 and 15 that form an inverted J shaped construction that mates with portions of the walls 28 and 29. In other words, the contact 11 substantially fits on the inner wall of the first appending wall (29) and on an outer wall of the second appending wall (28) for placement in the top housing portion. 
     Referring to FIG. 3, there is shown a partial front view of the charger housing and contact assembly 10. The contact 11 is preferably an integral piece of metal having portions 12, 14 and 16 slip fit within the top housing portion 24. The housing assembly is enclosed when the bottom housing portion 26 mates with the top housing portion 24. The substrate 20 having the contact pads 22 lies on the bottom housing portion 26. When the top and bottom housing portions (24 and 26) mate, the contact portion 12 becomes biased towards the contact pad 22 on the substrate 20. The contact is not easily removed externally since the contact portion 16 has a tongue portion 18 that is preferably wider than the width of the aperture 31. The contact 11 is easily removed after opening the housing by separating the top housing portion 24 from the bottom housing portion 26. The contact 11 including the portion 16 having the tongue portion 18 and extending feature 17 is easily hand-insertable and removable or replaceable. 
     The charger housing and contact assembly 10 is suitable for a variety of rechargeable batteries having different contact spacings or pitch. The different contact (11) spacings and heights could accomodate for different battery capacities or for different models without compromising in the alignment of the charger contact 11 with the battery contacts (not shown) and without compromising contact with the pads 22 on the printed circuit board 20. For instance, the top housing portion 24 could have a variable well (30) depth allowing for a variable contact height. 
     Referring to FIG. 4, there is shown a perspective view of the contact 11. As shown, the contact 11 again has a first portion 12 for providing contact to a substrate within the charger housing (not shown) and a mid-section or second portion 14 including an inverted J-shaped structure formed from members 13 and 15. Portion 12 provides good contact with the contact pad 22 on the substrate 20 as well as protecting the pad 22 from tin fretting by providing a wiping mechanism each time a battery is inserted into the well 30 of the battery charger housing 10 (see FIG. 1). The clip-on feature of the second portion 14 is formed by a stampedout member which creates the aperture 19 as shown. Finally, the third portion 16 of the contact 11 includes an extension feature 17 as well as a tongue 18. The feature 17 provides better contact with the connecting battery (not shown) and the tongue provides some spring action as well as some removal prevention of the contact for the housing.