Battery contacts

A battery contact (1) for connecting a battery (9) to an electric circuit (4) is comprised a first portion (2) for coupling to the electric circuit and a second portion (3) for coupling to the battery. The contact is made in one piece of electrically conductive sheet metal and is cut and bent so as to form the second portion into a tapered helical spring. The first portion (2) is formed with two retaining prongs (6,7) which facilitate locating and fixing the contact to the electric circuit (4) and a tab 8 which is used for soldering the contact to the electric circuit. In order to allow the contact to be easily picked-up in an automatic manufacturing line, a flat handling portion (11) is provided between the first and second portions.

BACKGROUND OF THE INVENTION 
This invention relates to battery contacts which are used to provide an 
electrical connection between an electric circuit and a battery. Such 
contacts generally comprise one portion for coupling to the circuit and a 
second portion for contact with the battery. In order to maintain adequate 
electrical connection with the battery, the second portion is often made 
in the form of a spring which exerts sufficient force against the battery 
to maintain electrical connection even under stress conditions. 
Such springs have normally been made as either leaf springs or helical 
springs. The leaf-spring version generally consists of a flat, battery 
connecting portion attached via a bent portion to the circuit-connecting 
portion, the bend providing the spring effect. The helical spring version 
generally consists of a round-wire helical spring portion, usually with 
the helix being in a conical configuration, attached to the 
circuit-connecting portion. This circuit-connecting portion has also 
generally been made of round-wire so as to be integral with the spring 
portion. 
A problem with the leaf spring type battery contacts is that they do not 
readily facilitate the use of different size batteries as they do not 
exert sufficient force to maintain good electrical contact with a variety 
of battery sizes. The helical spring type battery contacts are better at 
facilitating the use of different size batteries but, having round-wire 
circuit connecting portions renders them difficult to use on automatic 
assembly lines since it requires very accurate sensing to enable round 
wire ends to be picked up and positioned by automatic apparatus. 
Furthermore, such round wire battery contacts cannot be picked up by 
vacuum operated pick-up arms as there is insufficient surface area for the 
vacuum to work against. 
It is, therefore, an object of the present invention to provide a battery 
contact which can be used with a wide variety of battery sizes and which 
can easily be found and handled by automatic assembly lines. 
SUMMARY OF THE INVENTION 
Accordingly, the invention provides a battery contact manufactured in one 
piece from electrically conductive sheet metal comprising a first portion 
for coupling to an electric circuit and a second portion in the form of a 
helical spring for coupling to a battery. The second portion is preferably 
in the form of a tapered helical spring. Also, there is preferably 
provided a handling portion between the first portion and the spring 
portion, the handling portion conveniently being substantially flat in 
order to facilitate pick-up using vacuum operation. In a preferred 
embodiment, the first portion includes at least one tab for connection to 
an electric circuit, such as a printed circuit board and preferably also 
includes at least one retaining prong for locating and fixing the battery 
contact to the electric circuit before soldering takes place.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Thus, the drawings show several views of a battery contact 1 having a first 
portion 2 for coupling to an electric circuit and a second portion 3 for 
contacting a battery. The electric circuit is represented by part of a 
printed circuit board (PCB) 4 and the battery is designated 5. However, 
neither the PCB nor the battery are shown in all of the views. 
The contact 1 is manufactured from sheet metal by a process of punching a 
blank from the sheet and then simply bending the blank into the correct 
shape as shown in the drawings. The metal should, of course, be 
electrically conductive and also springy. Examples of suitable materials 
are stainless steel and beryllium copper although any similar material may 
alternately be used. 
The first portion 2 of the contact is designed for connection to a printed 
circuit board for use in instruments such as pagers, radios, etc. It 
comprises two parallel prongs 6, 7 and a tab 8 arranged perpendicularly to 
the prongs. The two prongs enter through respective holes 9 in the PCB 4 
and are then bent over to retain the battery contact on the PCB. The two 
prongs 6,7 are shown in FIG. 4 passing through holes in the PCB 4 and in 
FIG. 3, one of the prongs, 7, is shown bent over. The tab 8 sits flat 
against the PCB 4 providing self-location, self-fixturing and stability of 
the contact prior to soldering of the tab 8 to the PCB 4. 
The second portion 3 of the contact is shaped in the form of tapered 
helical spring. Of course, since the contact is made of sheet metal, the 
helices of the spring are not round in cross-section, but are in the form 
of a strip of metal coiled in a helical manner with gradually reducing 
radius toward the end of the spring remote from the first portion 2. This 
end of the spring is used to contact the battery and includes three radial 
prongs 10 which are directed towards the axis of the spring at its outer 
end for contact with the battery. 
In order to facilitate the use of the battery contact in an automatic 
manufacturing line where the contacts are required to be picked up and 
placed by automatic robot-like arms the battery contact 1 is formed with a 
substantially flat handling portion 11 between the first, electric circuit 
coupling portion 2 and the second, battery contacting portion 3. This 
handling portion 11 allows the contact to be easily picked up using vacuum 
pick-up arms and placed in the correct position on the PCB 4. It will be 
apparent that although the electric circuit coupling portion 2 and the 
handling portion 11 have been described with particular features and 
shapes, any desired shape that may be cut out of sheet metal may be used 
within the scope of this invention according to the type of electric 
circuit the contact is to be coupled to and the type of pick-up means 
employed in the automatic manufacturing line.