TECHNICAL FIELD OF THE INVENTION

The present invention relates to a battery charger according to the preamble of the appended independent claim.

BACKGROUND OF THE INVENTION

Battery chargers are used for charging electrical devices, such as mobile phones, laptops and tablet computers. Many battery chargers are equipped with an interchangeable plug so that by changing the plug the battery charger can be connect- ed to different types of socket outlets. An interchangeable plug thus enables the same battery charger to be used in countries where different standards are complied with.

Various ways are known to detachably couple a plug to a battery charger. For example in one known battery charger, the plug is received in a recess of the charger body. The plug is slid into its place along guiding grooves provided in the recess, and interlocked with the charger body by means of a locking mechanism. The plug is detached from the charger body by pressing a release button of the locking mechanism, and sliding the plug away from the charger body.

A problem associated with the above described battery charger and other known battery chargers having an interchangeable plug is that the detachment of the plug requires the user to simultaneously press the release button of the locking mechanism and move the plug relative to the charger body. This is difficult, and can even be impossible for some users.

OBJECTIVES OF THE INVENTION It is an objective of the present invention to reduce or even eliminate the prior art problems presented above.

It is an objective of the present invention to provide a battery charger having an interchangeable plug. It is also an objective of the invention to provide a battery charger to which a plug may be easily attached and from which a plug may be easily detached. It is a further objective of the invention to provide a battery charger from which a plug may be detached without pressing a release button. In order to realise the above-mentioned objectives, the battery charger according to the invention is characterised by what is presented in the characterising part of the appended independent claim. Advantageous embodiments of the invention are described in the dependent claims. DESCRIPTION OF THE INVENTION

A typical battery charger according to the invention comprises a body and a plug detachably coupled to the body. In a typical battery charger according to the invention the plug comprises a coupling part having a bottom and two sides, each of said sides comprising a first guiding rail provided with a locking slot, and the body comprises a coupling recess for receiving the coupling part, said coupling recess having a bottom and two opposite side walls, each of said side walls comprising a first guiding groove provided with a locking spring, wherein the first guiding grooves are arranged to receive the first guiding rails so that the locking springs are engageable with the locking slots. A battery charger according to the invention is equipped with an interchangeable plug. The plug may comprise protruding prongs, blades or pins that fit into matching slots or holes in a socket outlet. Depending on the type of the plug, the battery charger may be coupled with different types of socket outlets.

The first guiding rails are arranged to be slideable along the first guiding grooves. The plug is attached to the charger body by sliding the first guiding rails along the first guiding grooves until the locking springs are engaged with the locking slots.

The plug is interlocked with the body by means of the locking springs and slots.

The plug is detached from the charger body by moving the plug in the opposite direction, whereby the locking springs are disengaged from the locking slots and the first guiding rails are slid away from the first guiding grooves.

The coupling part and the coupling recess are preferably essentially rectangular. The coupling part may comprise a bottom, two opposite sides, and two opposite ends. The coupling recess may comprise a bottom, two opposite side walls, and two opposite ends. The coupling part and the coupling recess are dimensioned in such a manner that the coupling part fits into the coupling recess. The first guiding rails located on the opposite sides of the coupling part and the first guiding grooves located on the opposite side walls of the coupling recess are arranged symmetrically with each other so that the first guiding grooves may receive the first guiding rails. When the locking springs are engaged with the locking slots, a first end of the coupling part is preferably in contact with a first end of the coupling recess. The locking springs are preferably located near the first end of the coupling recess, and the locking slots are preferably located near the first end of the coupling part. A second end of the coupling recess is preferably open, whereby the coupling part may pass through the second end of the coupling recess when the plug is attached to or detached from the body.

At its rest position the locking spring protrudes from the first guiding groove. The first guiding groove may be provided with an aperture through which the locking spring is arranged to protrude. When the first guiding rail comes into contact with the locking spring, the first guiding rail presses the locking spring towards the first guiding groove. When the locking slot of the first guiding rail comes into alignment with the locking spring, the locking spring is projected into the locking slot, whereby the plug is interlocked with the body. The locking spring can be made of different materials, such as for example metal or plastic. The locking spring can be formed, for example, from a metal strip which is bent into a desired shape. The locking spring is preferably a formed spring such as a plate spring or a flat spring. The two locking springs can be separate parts or they can be connected together to constitute a locking spring assembly.

In a battery charger according to the invention the plug can be attached and de- tached easily. Especially, the detachment of the plug is much easier than in the prior art battery chargers because the detachment of the plug does not require any release button to be pressed. The plug may be attached and detached simply by moving the plug relative to the body.

According to an embodiment of the invention the locking spring comprises a bent portion made of a metal strip for engaging with the locking slot. Preferably, the bent portion has a shape that essentially corresponds to the shape of the locking slot. The bent portion protrudes from the first guiding groove. The bent portion is preferably arranged to protrude through an aperture provided in the first guiding groove. The bent portion is bendable in a direction perpendicular to the longitudi- nal direction of the first guiding groove.

The bent portion can have various shapes. The bent portion can be curved and/or comprise one or more bends and/or straight parts. The bent portion can, for example, comprise two straight parts that are arranged at an angle to each other. The angle between the straight parts can be, for example, 90-160 degrees, 100- 150 degrees, or 1 10-130 degrees. Preferably, the bent portion has a symmetrical shape, such as for example a shape of V or U. The bent portion having a symmetrical shape is arranged in the first guiding groove in such a manner that its bottom part points to the coupling recess and its first and second end are arranged into the aperture. Due to the symmetrical shape of the bent portion the forces that are needed for the attachment and detachment of the plug can be made essentially equal.

The bent portion and the locking slot are preferably arranged to have congruent shapes so that the bent portion fits into the locking slot. For example, if the bent portion is V-shaped, the locking slot comprises a corresponding V-shaped portion. According to an embodiment of the invention the first guiding rails extend from a first end of the coupling part towards a second end of the coupling part, and the first guiding grooves extend from a first end of the coupling recess towards a second end of the coupling recess. When the second end of the coupling recess is open, the first guiding grooves may extend essentially to the second end of the coupling recess. The first guiding rails may extend essentially to the second end of the coupling part. The longer the first guiding rails and grooves are, the stronger the coupling between the plug and the charger body is.

According to an embodiment of the invention each of the sides of the coupling part comprises a second guiding rail arranged consecutively with the first guiding rail, and each of the side walls of the coupling recess comprises a second guiding groove arranged consecutively with the first guiding groove, wherein the second guiding grooves are arranged to receive the second guiding rails. The first and the second guiding rail as well as the first and the second guiding groove are arranged at a distance from each other. The lengths of the first and the second guiding rails are preferably essentially the same. Also the lengths of the first and the second guiding grooves are preferably essentially the same.

According to an embodiment of the invention the plug is arranged to be coupled to the body in such a manner that the plug is moved in a first coupling direction to a first position in which the first guiding rails are located between the first and the second guiding grooves, and then the plug is moved in a second coupling direction, which is perpendicular to the first coupling direction, from the first position to a second position in which the locking springs are engaged with the locking slots. When the plug is removed from the body, the plug is first moved in a direction opposite to the second coupling direction, and then from the first position in a direc- tion opposite to the first coupling direction. The coupling recess may comprise in its longitudinal direction a widened portion between the first and the second guiding grooves, and the coupling part may comprise in its longitudinal direction a narrowed portion between the first and the second guiding rails. The width of the widened portion is larger than the width of the coupling recess portions comprising the coupling grooves. The width of the narrowed portion is smaller than the width of the coupling part portions comprising the coupling rails. The widened portion is dimensioned in such a manner that the coupling part portion comprising the first guiding rails fit through it.

According to an embodiment of the invention the first and/or the second guiding groove is formed on the side wall with a projection member extending in the longitudinal direction of the side wall. In other words, the projection member and the bottom of the coupling recess define the guiding groove along which the guiding rail may move. Preferably, all the guiding grooves of the coupling recess are formed with projection members. A projection member defining the second guiding groove may comprise an end part, which connects the projection member at its one end to the bottom of the coupling recess. Preferably, the end part is located at the end which is closer to the first end of the coupling recess, whereby the end part prevents the first guiding rail from sliding into the second guiding groove when the plug is detached from the charger body. According to an embodiment of the invention the bottom of the coupling recess comprises two contact springs arranged consecutively in the longitudinal direction of the coupling recess, and the bottom of the coupling part comprises two contact elements arranged consecutively in the longitudinal direction of the coupling part, wherein the contact springs are in contact with the contact elements when the locking springs are engaged with the locking slots. The contact springs as well as the contact elements are arranged at a distance from each other.

The contact springs and the contact elements provide an electrical connection between the plug and the body. The contact springs and the contact elements are made of metal. The contact element is connected to an electrical pin of the plug, or it forms an integral part of the electrical pin. The contact elements convey electrical current to the contact springs, when the electrical pins of the battery charger are connected to holes of a socket outlet (AC power socket). The contact springs are connected to a circuit board of the battery charger which circuit board comprises electronic components. According to an embodiment of the invention the bottom of the coupling recess comprises a rail extending in the longitudinal direction of the coupling recess, and the bottom of the coupling part comprises a groove extending in the longitudinal direction of the coupling part, wherein the rail is arranged to be slideable along the groove.

The contact elements are preferably located in the groove. This arrangement increases electrical safety because the contact elements may not be easily touched in an accidental case where the plug is not attached to the charger body and the contact elements are live. When the contact elements are located in the groove, the contact springs are arranged in connection with the rail.

According to an embodiment of the invention the locking spring is connected to the body in a floating manner so that the locking spring may move in the longitudinal direction of the first guiding groove. By connecting in a floating manner is meant that the locking spring is not tightly fixed to the body, but may move a certain amount in both directions of the first guiding groove.

When the first guiding rail comes into contact with the locking spring, a front end of the first guiding rail presses the locking spring towards the first guiding groove. At the same time the locking spring slightly moves in the moving direction of the first guiding rail. When the plug is removed from the body, an edge of the locking slot presses the locking spring towards the first guiding groove. At the same time the locking spring slightly moves in the moving direction of the first guiding rail.

According to an embodiment of the invention a front end of the first guiding rail is rounded or bevelled. The rounded or bevelled end reduces the force that is needed in attaching the plug to the body. The front end of the first guiding rail is prefer- ably shaped in such a manner that it conforms to the shape of the bent portion.

The exemplary embodiments of the invention presented in this text are not interpreted to pose limitations to the applicability of the appended claims. The verb "to comprise" is used in this text as an open limitation that does not exclude the existence of also unrecited features. The features recited in the dependent claims are mutually freely combinable unless otherwise explicitly stated.

BRIEF DESCRIPTION OF THE DRAWINGS

The novel features which are considered as characteristic of the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the description of specific embodiments when read in connection with the accompanying drawings.

Figs. 1A-1 B illustrate a body of a battery charger according to an embodiment of the invention, figs. 2A-2B illustrate a plug that can be detachably coupled to the body according to figs. 1A-1 B, fig. 3 illustrates the attachment and detachment of the plug according to figs. 2A-2B, and fig. 4 illustrates a partial cross section of a battery charger according to an embodiment of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

A body and a plug of a battery charger according to an embodiment of the invention are illustrated in figs. 1A-1 B and 2A-2B, respectively. The battery charger comprises an interchangeable plug, and is suitable for charging electrical devices, such as for example mobile phones.

Figs. 1A-1 B illustrate different views of the body of the battery charger. The body 100 comprises a coupling recess 101 for receiving a coupling part of a plug. The coupling recess 101 comprises a bottom 102 and two opposite side walls 103. Each of the side walls 103 comprises a first and a second guiding groove 104, 105, which are formed on the side wall 103 with a first and a second projection member 106, 107 which extend in the longitudinal direction of the side wall 103. The first and the second projection member 106, 107 are arranged at a distance from each other so that the coupling recess 101 comprises in its longitudinal direc- tion a widened portion 108. The first projection member 106 ends to a first end 109 of the coupling recess 101 . The second projection member 107 comprises an end part 1 10, which connects the projection member at its one end to the bottom 102 of the coupling recess 101 . The end part 1 10 is located at the end which is closer to the first end 109 of the coupling recess 101 . A second end 1 1 1 of the coupling recess 101 is open.

The first guiding grooves 104 are provided with an aperture on the side wall 103 through which aperture a locking spring 1 12 protrudes into the coupling recess 101 . The locking spring 1 12 comprises a V-shaped portion which is arranged in such a manner that its tip points to the coupling recess 101 . The locking springs 1 12 are located near the first end 109 of the coupling recess 101 .

The bottom 102 of the coupling recess 101 comprises two contact springs 1 13 which are arranged in connection with a rail 1 14 extending in the longitudinal direction of the coupling recess 101 . The contact springs 1 13 are connected to a circuit board (not shown) which is located inside the body 100. The battery charger may be coupled to an electrical device to be charged with a cable 1 15.

Figs. 2A-2B illustrate different views of the plug of the battery charger. The plug 200 comprises a coupling part 201 which fits into the coupling recess 101 of the body 100 so that the plug 200 may be coupled to the body 100.

The coupling part 201 comprises a bottom 202 and two sides 203. Each of the sides 203 comprises a first and a second guiding rail 204, 205 which are arranged consecutively with each other. The first and the second guiding rail 204, 205 are adapted to slide in the first and the second guiding groove 104, 105, respectively. The first and the second guiding rail 204, 205 are arranged at a distance from each other so that the coupling part 201 comprises in its longitudinal direction a narrowed portion 206. A front end of the first guiding rail 204 is rounded. The rounded end reduces the force that is needed in attaching the plug 200 to the body 100.

The first guiding rail 204 comprises a locking slot 207, which has essentially the same shape as the bent portion of the locking spring 1 12 so that the locking spring 1 12 fits into the locking slot 207. The locking slot 207 of the first guiding rail 204 is located near a first end 208 of the coupling part 201 . The plug 200 is attached to the charger body 100 by sliding the guiding rails 204, 205 along the guiding grooves 104, 105 until the locking springs 1 12 are engaged with the locking slots 207. The plug 200 is interlocked with the body 100 by means of the locking springs 1 12 and the locking slots 207. When the locking springs 1 12 are engaged with the locking slots 207, the first end 208 of the coupling part 201 is in contact with the first end 109 of the coupling recess 101 .

The bottom 202 of the coupling part 201 comprises two contact elements 209 which are arranged in a groove 210 which extends in the longitudinal direction of the coupling part 201 . The rail 1 14 on the bottom 102 of the coupling recess 101 is adapted to slide in the groove 210. When the locking springs 1 12 are engaged with the locking slots 207, the contact elements 209 are in contact with the contact springs 1 13, whereby they provide an electrical connection between the plug 200 and the body 100. The contact elements 209 are connected to electrical pins 21 1 which are meant to be connected to holes of a socket outlet. Fig. 3 illustrates the procedure of attaching the plug to the charger body (from left to right), and the procedure of detaching the plug from the charger body (from right to left).

The plug 200 is attached to the body 100 as follows. First, the plug 200 is arranged to a first position in which the first guiding rails 204 are located between the first and the second guiding grooves 104, 105. This is done by moving the plug 200 relative to the body 100 in a first coupling direction so that the first guiding rails 204 are received into the widened portion 108 of the coupling recess 101 , and the second projection members 107 are received into the narrowed portion 206 of the coupling part 201 . The plug 200 is moved in the first coupling direction until the bottom 202 of the coupling part 201 is against the bottom 102 of the coupling recess 101 , whereby the rail 1 14 located in the bottom 102 of the coupling recess 101 is received into the groove 210 located in the bottom 202 of the coupling part 201 .

From the first position the plug 200 is arranged to a second position in which the plug 200 is interlocked with the body 100 by means of the locking springs 1 12 and the locking slots 207. This is done by moving the plug 200 relative to the body 100 in a second coupling direction, which is perpendicular to the first coupling direction, so that the first and the second guiding rails 204, 205 slide along the first and the second guiding grooves 104, 105, respectively. When the first guiding rail 204 comes into contact with the locking spring 1 12, the first guiding rail 204 presses the locking spring 1 12 towards the first guiding groove 104. When the locking slot 207 of the first guiding rail 204 comes into alignment with the locking spring 1 12, the locking spring 1 12 is projected into the locking slot 207. The first end 109 of the coupling recess 101 prevents the plug 200 from moving any further in the se- cond coupling direction. At the second position the contact springs 1 13 are in contact with the contact elements 209, thus providing an electrical connection between the plug 200 and the body 100.

When the plug 200 is removed from the body 100, the plug 200 is first moved in a direction opposite to the second coupling direction, whereby the locking springs 1 12 are disengaged from the locking slots 207. The end parts 1 10 of the second projection members 107 prevent the first guiding rail 204 from sliding into the second guiding groove 105. From the first position the plug 200 is moved in a direction opposite to the first coupling direction.

Fig. 4 illustrates a partial cross section of a battery charger according to an em- bodiment of the invention. Fig. 4 shows how the locking springs 1 12 are engaged with the locking slots 207 in a situation where the plug 200 is attached to the body 100. In this embodiment the locking springs 1 12 are parts of the same metal strip which is bent into a shape which allows the locking springs 1 12 to move in the second coupling direction when the plug 200 is attached to the body 100, and in the direction opposite to the second coupling direction when the plug 200 is detached from the body 100.

Only advantageous exemplary embodiments of the invention are described in the figures. It is clear to a person skilled in the art that the invention is not restricted only to the examples presented above, but the invention may vary within the limits of the claims presented hereafter. Some possible embodiments of the invention are described in the dependent claims, and they are not to be considered to restrict the scope of protection of the invention as such.