EP3195384A1

EP3195384A1 - Device for connection of button cell batteries to a circuit board and use

Info

Publication number: EP3195384A1
Application number: EP15718137.1A
Authority: EP
Inventors: Jan Jægergaard
Original assignee: Orbiloc Aps
Current assignee: ORBILOC APS
Priority date: 2014-05-09
Filing date: 2015-04-08
Publication date: 2017-07-26
Also published as: WO2015169318A1; DK178200B1

Abstract

The invention includes a device (15) designed to contain at least one button cell battery (6), where the device (15) includes at least one contact spring (7) with at least another contact surface (5a), designed to provide electrical contact to another conducting track (3) on a circuit board (1). The contact spring (7) also includes at least a first contact surface (4a) designed to provide electrical contact with the other battery terminal (6b). The first battery terminal (6a) and a first conducting track (2) on the circuit board (1 ) include a joint contact area. The device (15) includes at least one holder item (9) with first items, which first items are designed to fix the circuit board (1) and the device also includes other items, which other items are designed to fix the contact spring / the contact springs (7) in the holder item (9). With the invention it is achieved that it is thus possible to achieve a very compact product design since the batteries (6) are situated very close to the circuit board (1). Furthermore, the solution ensures easy mounting and easy access for changing the batteries (6) when the product is opened.

Description

Device for connection of button cell batteries to a circuit board and use

The invention relates to a device designed to contain at least one button cell battery, which battery / batteries have a first battery terminal and a second battery terminal and where the device includes a contact spring with at least another contact surface, which is designed to provide electrical contact to another conducting track on another surface on a circuit board, which contact spring includes at least one first contact surface, which is designed to provide electrical contact with the other battery terminal and where the first battery terminal and a first conducting track on the circuit board includes a joint contact area.

The invention also relates to the use of the device. In order to provide electronics with button cell batteries, there are required two connections between battery and circuit board. Traditional connection of button cell batteries uses two contact items, of which at least one is mounted, or installed subsequently, directly on the circuit board. These contact items ensure connection between circuit board and button cell battery such that the electronics is provided with power. At least one of the contact pieces must have spring characteristics in order to compensate for the mechanical tolerances that the circuit board and batteries have, and this is hereafter referred to as a contact spring. From US2002142648 is known a contact spring, which is either soldered on or is in another way mechanically fastened to a circuit board in order to create electrical contact to the battery terminals. One of the battery terminals is in direct contact with the circuit board, and the other battery terminal is in contact with the contact spring, which has then got contact to the circuit board. It has been found, that there are certain drawbacks of this known technology. This connection requires that the used contact springs are fastened directly on the circuit board. The fastening is most often carried out by soldering the contact spring fixed to the circuit board. Other solutions are also seen, where the contact spring is fastened with a mechanical lock on the circuit board. Common for these solutions is that they require handling in the mounting process of the circuit board, which either has to be carried out manually or is expensive to automate. From US6602080 is also known a contact spring, which is constructed for being mounted on a circuit board with surface mounted technology (SMT).

It has been found, however, that there are certain drawbacks of the known technology. The solutions with fixed contact spring cause that the batteries must be pushed in under the contact spring, in order to create contact to the battery terminals. This requires free space on the circuit board and possibly in the product and results in that a change of battery can be difficult and entail a risk of damaging the circuit board when the batteries are moved out and in under the contact spring.

There is also a risk of the batteries falling out again, unless there is inserted an extra item, which prevents this.

If the contact spring is soldered on, there is as a result of the spring characteristics and that the spring must hold the batteries pressed towards the circuit board, also risk of stressing the soldering, if there is not mechanical load alleviation, which increases the probability for mistakes.

It is therefore an object of the invention to improve the known technique and use. The object of the invention is achieved by a device of the in the introduction to claim 1 stated type, which is characterized in that the device includes at least one holder item, with first devices, which first devices are designed to fix the circuit board and that the device also includes other items, which other items are designed to fix the contact spring in the holder item. In this way it thus becomes possible that, by introducing a holder item and a loose contact spring for button cell batteries, the supply dependent circuit board can be produced solely by use of surface mounted technology (SMT), thus avoiding costly manual handling. The solution also allows a very compact product design since the batteries lie close against the circuit board. Furthermore, the solution ensures easy access to changing the batteries when the product is opened. The batteries can be mounted in a direction perpendicular to the circuit board, such that there is no need to move them in under the contact spring, which saves space on the circuit and in the product and there is no risk that the batteries can be displaced out of their correct position.

In addition, the construction contains no solderings that could potentially be stressed and thus fail.

Further appropriate embodiments of the device are stated in additional claims.

By an additional aspect of the invention, the device includes that the holding item includes a lower helping item and an upper helping item, which is designed to interact with each other.

It is hereby achieved that the design of the holding item is flexible and that the necessary function surfaces for fixing contacts spring, batteries and circuit board can be divided into two items.

By an additional aspect of the invention, the device includes that the lower helping item includes a thread and that the upper helping item includes another thread, which threads are designed to go in mesh with each other. It is hereby achieved that the lower helping item and the upper helping item can be fixed to each other.

By an additional aspect of the invention, the device includes that the first items include a surface on the upper helping item, which surface forms contact with a first surface on the circuit board and includes another surface on the lower helping item, which other surface forms contact with the second surface, different from the first surface on the circuit board.

It is hereby achieved that the circuit board is fixed in the correct position in relation to battery / batteries and the contact spring.

By an additional aspect of the invention, the device includes that the other items include at least one spring arm in the contact spring, which spring arm is designed to provide a friction between the spring arm and the holder item.

It is hereby achieved that the contact spring is fixed in the holder item.

By an additional aspect of the invention, the device includes that the contact spring includes at least a first spring surface, which first spring surface / surfaces are designed to be in contact with at least a first holding surface on the holder item, which first holder surface / surfaces are designed to have a fixed distance to the other surface on the circuit board. It is hereby achieved that the contact spring is fixed in the correct position such that the electrical connections to the circuit board and battery / batteries is maintained.

By an additional aspect of the invention, the device includes that the first contact surfaces and the other contact surfaces on the contact spring are coated with a metal, including nickel or gold.

It is hereby achieved that the electrical contact to the other battery terminal and to the other conducting track is maintained over time and is not weakened by oxidation or corrosion.

By an additional aspect of the invention, the device includes that the contact spring is manufactured from a metallic material or in a polymeric material.

It is hereby achieved that the necessary spring properties in the contact spring can be provided.

By an additional aspect of the invention, the device includes that the holder item is manufactured from polymeric, metallic or mineral material. It is hereby achieved that the holder item has the necessary mechanical properties to fix the circuit board and the contact spring.

As mentioned, the invention also relates to use of the device for connection of button cell batteries to a circuit board in electronic devices including in lamps and portable products.

Hereby it becomes possible to efficiently connect button cell batteries to a circuit board in electronic devices including portable products and in lamps.

The invention will now be explained more further with reference to the drawings, on which:

Fig. 1 shows a cutaway view of a device according to the invention

Fig. 2 shows a cutaway view of a device according to the invention with batteries and circuit board

Fig. 3 shows an exploded view of the device shown in fig. 2

Fig. 4 shows a part of the device according to the invention. Fig. 5 shows a circuit board

In fig. 1 is with (15) marked shown a device

On fig. 2 is with (1) marked shown a circuit board. The circuit board (1 ) is shaped cylindrical and has two sides, which two sides consist a first surface (1a) and another surface (1 b).

With (9) is shown a holder item, which consists of a lower helping item (9a) and an upper helping item (9b). With a first surface (13) on the upper helping item (9b), the circuit board (1 ) is supported on the first surface (1a), and with another surface ( 1) on the lower helping item (9a), the circuit board (1 ) is supported on the other surface (1b) such that the circuit board (1) is unambiguously placed in relation to the holder item (9).

The upper helping item (9b) is cylindrical with a thread (14b) on the external cylindrical surface. The internal cylindrical surface constitutes a third surface (16), which has contact to the circuit board's (1) cylindrical surface, which connects the 2 surfaces (1a, 1 b) on the circuit board (1), which cylindrical surface constitutes a third surface ( 7) on the circuit board (1). There is in the upper helping item (9b) placed at least one element, which emanates from the internal cylindrical surface and reaches in over the circuit board's (1) first surface (1a). This element has a surface, which forms contact to the circuit board's (1 ) first surface (1a) and which consists the first surface (13) in the holder item (9).

The holder item (9) thus includes the first surface (13) and the other surface (11)

With (6) indicated is shown a button cell battery. The battery's first terminal (6a) is in direct contact with the circuit board's (1) other surface (1b). The battery's other terminal (6b) is in contact with a contact spring (7). On fig. 2 and fig 3. are shown two batteries, but the device can also be used with another number of batteries.

On fig. 2 and fig. 3 is with (9a) indicated shown the lower helping item, which with the other surface (11) supports the circuit board (1 ) on the circuit board's other surface (1 b).

The lower helping item (9a) is cylindrical in its shape with an internal cylinder element, including an upper end surface, which constitutes the other surface (11 ) and an internal cylindrical surface, which constitutes a fourth surface (18), which encircles the batteries (6) and an external cylindrical surface, which is situated within the third surface (17) on the circuit board (1). The lower helping item (9a) also includes an external cylinder element, where there on the internal surface of this external cylinder element is a thread ( 4a).

The 2 cylindrical elements are connected and closed with a bottom element in the opposite end in relation to the second surface (11), which bottom element has an internal surface, which consists the first holding surface (10).

The lower helping item (9a) and the upper helping item (9b) together constitute the holding item (9).

On fig. 3 and 4 is with (8) shown a first spring surface on the contact spring (7), which, as shown in fig. 3, forms contact against a first holding surface (10) on the lower helping item (9a) in the holder item (9). On the figures, the first spring surface (8) is shown as a plane surface, but it can also have other shapes, including also being a part of a springy element on the contact spring (7).

The contact spring (7), which is mounted in the lower helping item (9a) includes at least a first contact leg (4), which with a first contact surface (4a) is in contact with the battery's other terminal (6b). The contact spring (7) also includes at least one other contact leg (5), which with an other contact surface (5a) is in contact with the circuit board (1 ).

Both the first contact surface (4a) and the other contact surface (5a) can be placed on springy elements on the contact spring (7). The contact spring is here shown as a bent thin plate item, which includes a mostly circular central plate, on which the one side constitutes the first holding surface (8). Around the middle of this central plate is a hole, where there along the internal periphery emanates three legs, which constitute the first contact legs (4). These legs are bent in an angle below 90 degrees in opposite direction of the normal to the first holding surface (8) and at the free ends of the first contact legs (4) are found surfaces, which are parallel with the central plate. On each of these surfaces is shaped a section of a sphere surface, which surfaces constitute the first contact surfaces (4a). The angle below 90 degrees ensures that the first contact legs (4) together with the material characteristics have springy properties and can provide a sufficient contact pressure between the first contact surfaces (4a) and the battery's other terminal (6b)

At the external periphery of the central plate, there emanates three legs, approximately perpendicular on the plate and in opposite direction of the normal to the first holding surface (8), where these legs constitute the other contact legs (5). On each of the free ends on these other contact legs (5) is found a surface, which approximately is a section of a circle, which surfaces constitute the other contact surfaces (5a). In the central place, there are on each side of each of these other contact legs (5) grooves, which emanate from the central plate's external periphery and in towards the center. These grooves result in that a part of each other contact leg (5) is parallel to the central plate, which allows a, for any of the other contact legs (5), independent deflection in direction of the first holding surface's (8) normal. This deflection ensures that the other contact legs (5) together with the material properties have springy properties and can provide a sufficient contact pressure between the first contact surfaces (5a) and the circuit board (1 )

In a preferred embodiment, there are three first contact legs (4) and three other contact legs (5) with the in the figures shown design, which results in a balanced support, but the invention is not limited to these numbers and designs.

On fig. 3 is with (16) indicated shown the third surface of the holder item (9) and with (17) indicated shown the third surface of the circuit board (1 ). These two surfaces (16, 17) are cylindrical in their design and the third surface (17) on the circuit board (1 ) is designed so that it fits within the third surface (16) on the holder item (9), allowing that the circuit board (1) can be encircled by the third surface (16) on the holder item (9). The third surface (16) on the holder item (9), thus forms contact with the third surface (17) on the circuit board (1) and ensures that the circuit board (1) is fixed relative to the holder item (9), in a plane parallel to the circuit board's (1) first surface (1a).

The method for fixing the circuit board (1) in a plane parallel to the circuit board's (1) first surface (1a) in relation to the holder item (9) is not limited to the method shown here, but can also be implemented with other methods, including with a hole in the circuit board (1) and a guide pin in the holder item (9). On fig. 4 is with (3) shown a conducting track on the circuit board's (1 ) other surface (1 b). The other contact surfaces (5a) have contact to the other conducting track (3) on the circuit board (1)

Both the first contact legs (4) and other contact legs (5) are preloaded and have spring properties, which ensure electrical contact despite the mechanical tolerances.

With (12) is shown at least one spring arm in the contact spring (7), which is in fixed mesh with the fourth surface (18) in the holder item (9), as a result of friction between spring arm (12) and fourth surface (18) in the holder item (9). This spring arm (12) can have other shapes than the one shown here and ensures that the contact spring (7) maintains its position relative to the holder item (9), if the holder item (9) is moved in relation to the circuit board (1 ). The method for retaining the contact spring is not limited to the method shown here, but can also be provided with other methods than shown here, including with a snap hook or by gluing. The fixing function can also be designed such that the contact spring (7) is controlled by the holding item (9) in certain directions and free to move in other directions.

The contact spring (7) will in a preferred embodiment be manufactured in a metallic material and be coated with nickel or gold, in order to ensure the electrical connections with the second battery terminal (6b) and with the second conductor track (3). The contact spring (7) can also be manufactured from other materials including polymeric materials, for example with conductive properties or with added conductive tracks. The material must also provide the mechanical and springy properties, which are required to provide adequate surface pressure at the electrical connection.

The contact spring (7) will in a preferred embodiment consist of an item, but can also consist of several items.

In fig. 5, the circuit board (1 ) is shown. On the circuit board's (1 ) second surface (1 b) is printed a first conductor track (2), which functions as contact area to the battery's first terminal (6a). There is also printed a second conductor track (3) on the same second surface (1 b) of the print, which is in contact with the contact spring's (7) second contact surface (5a) and thus to the battery's second terminal (6b) which is in contact with the contact spring's (7) first contact surface (4a). The first conductor track (2) and the second conductor track (3) are not in direct contact with each other.

The holder item (9) creates a backstop for the contact spring (7), such that there is enough surface pressure between the first contact legs' (4) first contact surfaces (4a) and second battery terminal (6b) and between the second contact legs' (5) second contact surface (5a) and second conductor track (3) on the circuit board's (1) second surface (1b). The backstop, which is achieved by the holder item (9) pressing with first holding surface (10) on the contact spring's (7), the spring surface (8), will together with the spring properties in the first contact legs (4) further ensure that the battery's first terminal (6a) is in electrical contact with the first conductor track (2) on the circuit board's (1) second surface (1 b). The lower helping item (9a) and the upper helping item (9b), are on fig. 1 and 2 shown with thread (14a) and thread (14b), which ensures that the two items can be screwed together and thus ensure that the items are properly positioned relative to each other and that there can be created the necessary backstop to the contact spring (7). Other assembly methods, including a snap connection or by gluing can also provide the required attachment. The lower helping item (9a) can also be linked directly to the circuit board (1), for example by a snap connection, which results in that the holder item (9) can consist of only the lower helping item (9a). The holder item (9) encircles, in a preferred embodiment, the batteries (6) and the circuit board (1) such that the batteries (6) and the circuit board (1) does not have the option to shift from their correct positions, and thus it is ensured that no errors occur as a result of the batteries having moved away from the contact surfaces on the circuit board (1) and on the contact spring (7). The batteries are encircled by the fourth surface (18) on the lower helping item (9a) and the circuit board is encircled by the third surface (16) on the upper helping item (9b). Both surfaces are included in the holder item (9)

When the lower helping item (9a) and the upper helping item (9b) are separated from each other, the contact spring (7) follows in this design with the lower helping item (9a) in the holder item (9), as a result of that the spring arms (12 ) and the friction between the spring arms (12) and the holder item (9), will keep the contact spring (7) fixed in the lower helping item (9) and thus in the holding item (9). This characteristic can in another embodiment be used to stop the electrical connection. The circuit board (1) will be able to continue to be supported in the upper helping item (9b) when the lower helping item (9a) is screwed off. By thus moving the lower helping item (9a), for example by turning it in the thread (14a) it is achieved that the electric circuit, which is supplied by power from the batteries is turned off, and that it is thereby possible to use this characteristic to an on / off function.

In another embodiment, not shown on the drawing, for example provided by leaving out the spring arms (12), the contact spring (7) will be able to move in relation to the lower helping item (9a), when the lower helping item (9a) is separated from the upper helping item (9b). The contact spring (7) will thus be able to be separated from the lower helping item (9a).

Holder item (9) will in a preferred embodiment be manufactured in a polymeric material, but can also be manufactured in a metallic or mineral material. The holder item (9) will typically be manufactured by an injection mould process in a non conducting material.

The holding item (9) has thus got the necessary mechanical properties to fix both the circuit board (1) and the contact spring (7)

With a loose contact spring (7) or with the contact spring fixed in the holder item (9), it is achieved that the batteries (6) can easily be replaced, when the holder item is loosened from the circuit board (1 ).

With a loose contact spring (7) it is achieved that the circuit board (1) can be produced only by use of surface mounted technology (SMT) and expensive manual handling is thereby avoided. It is also achieved that the contact spring (7) must not be soldered and the risk is thereby avoided of stressing such a soldering and a subsequent following potential error in the electrical connection. Moreover, a very compact product design can be achieved, since the batteries (6) are placed very close to the circuit board (1) and that the batteries (6) are mounted in a direction perpendicular to the print and does thereby not require free space on the circuit board or in the construction to push the batteries (6) in under the contact spring (7)

On the shown figure, the device (15) is shown cylindrical and the circuit board (1) is therefore also cylindrical. However, the invention can also be used for other shapes, including rectangular / quadratic circuit boards (1). In that case, the device (15) will take a geometry, which can enclose the circuit board (1 ), for example also rectangular or quadratic.

In another embodiment, the device will be able to provide a waterproof enclosure of the batteries (6) and the circuit board (1) and thereby protect both the batteries (6) and the circuit board (1 ) from external influences, including water and chemicals.

Claims

P A T E N T C L A I M S

Device (15) designed to contain at least one button cell battery (6), which battery / batteries (6) have a first battery terminal (6a) and a second battery terminal (6b) and where the device (15) includes a contact spring (7) with at least another contact surface (5a), which is designed to provide electrical contact to another conducting track (3) on another surface (1 b) on a circuit board (1 ), which contact spring (7) includes at least one first contact surface (4a), which is designed to provide electrical contact with the other battery terminal (6b) and where the first battery terminal (6a) and a first conducting track (2) on the circuit board (1) includes a joint contact area characterized in that the device (15) includes at least one holder item (9), with first devices, which first devices are designed to fix the circuit board (1 ) and that the device also includes other items, which other items are designed to fix the contact spring (7) in the holder item (9).

Device (15) according to claim 1 characterized in that the holder item (9) includes a lower helping item (9a) and an upper helping item (9b), which is designed to co-operate with each other.

Device (15) according to claim 2 characterized in that the lower helping item (9a) includes a thread (14a) and that the upper helping item (9b) includes another thread (14b), which threads (14a, 14b) are designed to go in mesh with each other.

Device (15) according to claim 1 to 3 characterized in that the first items include a first surface (13) on the holder item (9), which first surface (13) forms contact with a first surface (1a) on the circuit board (1) and includes another surface (11) on the holder item (9), which other surface (11) forms contact with the other surface (1b), different from the first surface (1a) on the circuit board (1 ).

5. Device (15) according to one or more of claims 1 to 4 characterized in that the other items include at least one spring arm (12) in the contact spring (7), which spring arm (12) is designed to provide a friction between the spring arm / spring arms (12) and the holder item (9).

6. Device (15) according to one or more of claims 1 to 5 characterized in that the contact spring (7) includes at least a first spring surface (8), which first spring surface / surfaces (8) are designed to be in contact with at least a first holding surface (10) on the holder item (9), which first holder surface / surfaces (10) are designed to have a fixed distance to the other surface (1 b) on the circuit board (1 ).

Device (15) according to one or more of claims 1 to 5 characterized in that the first contact surfaces (4a) and the other contact surfaces (5a) on the contact spring (7) are covered with a metal, including nickel or gold.

Device (15) according to one or more of claims 1 to characterized in that the contact spring (7) is manufactured from metallic material or in a polymeric material.

Device (15) according to one or more of claims 1 to characterized in that the holder item (9) is manufactured polymeric, metallic or mineral material.

10. Use of the device (15) according to one or more of claims 1 to 9 for connection of button cell batteries (6) to a circuit board (1 ) in electronic devices including in lamps and portable products.