GB2381669A

GB2381669A - Folding plug

Info

Publication number: GB2381669A
Application number: GB0125985A
Authority: GB
Inventors: Nigel Malcolm Ogier
Original assignee: Individual
Current assignee: Individual
Priority date: 2001-10-30
Filing date: 2001-10-30
Publication date: 2003-05-07
Anticipated expiration: 2021-10-30
Also published as: GB0125985D0; GB2381669B

Abstract

An electrical plug has a connecting pin (24) being moveable on an arm (16) about an axis parallel to the connecting pins (8 or 9). Preferably, the upper part of a vertical flash plate (27) which is recessed to substantially accommodate and fix the moveable arm can be folded through 90 degrees to be parallel to the connecting pins. A cavity together with a closure (14) in the body of the plug which must be closed to permit the moveable arm (16) or the vertical flash guard (27) to assume an operative condition such that it would permit the plug to then be inserted into an electrical socket.

Description

ELECTRICAL PLUGS The present invention relates to electrical plugs and is concerned in particular, although not exclusively, with an electrical plug for use with portable electrical equipment such as, for example, laptop computers or digital video cameras.

Portable electrical equipment is often provided with an electrical plug and cable which can be connected between the piece of equipment and a standard electrical wall socket to provide the piece of equipment with a power source when the piece of equipment is being used in proximity to such a wall socket.

The electrical plug typically used comprises a standard three pin or two pin plug for use in standard three aperture or two aperture wall sockets in the UK or continental Europe respectively. However, such standard plugs take up a relatively large amount of space when being carried with the piece of portable equipment, in a carry case or other device typically used to transport such equipment.

According to a first aspect of the present invention there is provided an electrical plug comprising a casing and at least two exposed, parallel pins which are carried by the casing, at least one of the pins being so arranged as to be movable relative to the casing about an axis parallel to said one pin, from an inoperative condition in which said pins cannot be inserted into an electrical socket to an operative position in which said pins can be inserted into an electrical socket.

Preferably said movable pin is mounted on an arm. the arm being pivotally connected to the casing. This can facilitate the plug being more compact when said one pin is in the inoperative condition.

Preferably the arm is made from an insulating material.

Preferably the plug comprises three pins, two of the pins being fixed relative to the casing.

Preferably the casing is of substantially flat box shape, with the two fixed pins projecting from an edge face thereof, and the arm extends substantially at 90 to the casing in the operative position and lies substantially parallel to the base of the box in the inoperative position.

The arm is preferably of substantially plate-form, and the casing is preferably provided with a recess which substantially accommodates the arm in the inoperative position, thereby providing a particularly compact plug for storage and transport.

Preferably said movable pin is an earth pin.

Preferably the plug further comprises a flash plate having a lower half adjacent to and parallel with said edge face from which the fixed pins project and having an upper half so arranged to be movable relative to the lower half from an inoperative position in which said pins cannot be inserted into an electrical socket, to an operative position in which said pins can be inserted into said socket.

Preferably the upper half of the flash plate has a slot through which the movable pin extends when the movable pin is in the operative position and the upper half of the flash plate is in the operative position, the slot engaging the pin and preventing the pin from moving to the inoperative position when the upper half is in the operative position.

According to a second aspect of the present invention there is provided an electrical plug comprising a casing having a cavity adapted to receive a fuse, and a closure to close the cavity, the closure being associated with electrical contact

means, the plug being so arranged that, in use, when both the fuse is received in the cavity and the cavity is closed by the closure the electrical contact means completes an electrical circuit and, when the cavity is not closed by the closure, the electrical contact means breaks the electrical circuit.

Preferably said closure comprises a planar cover pivotally mounted on the casing and said electrical contact means comprises a conductive tab extending from the cover, substantially perpendicularly to the plane of said cover.

Preferably retaining means are provided to co-operate with the closure to retain the closure in the closed position, at least when the plug is in the operative condition.

Preferably the cavity is arranged so that the fuse is received in the cavity with the fuse parallel to the pins and the cover is pivotally mounted for movement about an axis parallel to the pins.

Alternatively, the cavity is arranged so that the fuse is received in the cavity with the fuse perpendicular to the pins and the cover is pivotally mounted for movement about an axis perpendicular to the pins.

According to a third aspect of the present invention there is provided an electrical plug comprising the features of both the first and second aspects of the invention.

Preferably the securing means comprises said movable arm which, when in the operative position, co-operates with part of said closure when the cavity is closed by the closure.

Other embodiments of the present invention may include any combination of the features or limitations referred to herein.

The present invention may be carried into practice in various ways, but folding three-pin plugs in accordance with the invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a perspective view of a first plug in accordance with the invention shown in a folded, inoperative condition but with the fuse cover open ; Figure 2 is a perspective view corresponding to Figure 1 but with the fuse cover closed and with a pivotal pin arm in an intermediate condition ; Figure 3 is a perspective view corresponding to Figures 1 and 2 but showing the plug in an operative condition; Figure 4 is a perspective view of an alternative embodiment of the plug in a folded, inoperative condition but with the fuse cover open; Figure 5 is a perspective view corresponding to Figure 4 but with the fuse cover closed, the pivotal pin arm in an operative condition and a flash plate in an intermediate condition; and Figure 6 is a perspective view corresponding to Figures 4 and 5 but showing the plug in an operative condition.

Referring initially to Figure 1. an electrical plug 1 comprises a casing 2 of generally flat box shape having a square, planar, base 3. A planar, rectangular face 4 is parallel with and spaced apart from part of the base 3. A second planar, rectangular face 5 is adjacent the first face 4 and parallel with but spaced further from an adjacent part of the base 3. A step 6 is defined between the first face 4 and the second face 5. The first face 4 and the second face 5 are connected to the base 3 by side walls 7 which are substantially perpendicular to

the base 3 and the faces 4 and 5. The casing 2 is made from an electrically insulating material such as a plastics material. Any other suitable material could, alternatively be used.

A first pin 8 and a second parallel pin 9 project substantially perpendicularly from one of the side walls 7. Each pin 8,9 is made from an electrically conducting material and each pin 8,9 is part of a plug circuit as is well known in the art. The plug circuit is contained within the casing 2. It is envisaged that each pin 8,9 is a live/neutral pin dimensioned to be inserted into the live/neutral aperture of a standard, UK, three aperture electric wall socket.

The casing 2 is provided with an elongate cavity 10 which extends downwardly from the second face 5 towards the base 3 between second pin 9 and a side wall 7 opposed from second pin 9. The cavity 10 is substantially parallel to pin 9. The cavity 10 opens onto the second face 5. The cavity 10 is dimensioned to receive a fuse 11 as is commonly used in electrical apparatus in the UK. Resilient spring clips (not shown) may be provided within the cavity 10 to clip the fuse 11 in the cavity 10 so that the fuse is secured.

When the fuse 11 is secured within the cavity 10, one end 12 of the fuse 11 touches an electrical contact (not shown) at one end of the cavity 10. The other end 13 of the fuse 11 is adjacent but not touching another electrical contact (not shown) at an opposed end of the cavity 10. Each electrical contact forms part of the plug circuit.

The plug 1 further comprises a closure to close the cavity 10. The closure comprises a planar, rectangular fuse cover 14 made from an electrically insulating material. The closure is associated with electrical contact means comprising an electrically conducting tab 15 which extends perpendicularly from the underside of part of the cover 14.

A side edge of the cover 14 is pivotally mounted at one end of the casing 2 so as to be movable, about an axis parallel with pins 8 and 9, between an open position (as shown in Figure 1) to a closed position in which the cover closes the cavity 10 (as shown in Figures 2 and 3). When the cover 14 is in the closed position, the electrically conducting tab 15 extends into the cavity 10 between said second end 13 of the fuse 11 and the adjacent electrical contact. When in this position, the electrically conducting tab 15 completes the plug circuit as will be further described hereinafter.

The plug 1 further comprises an arm 16 in the form of a plate having two opposed rectangular ends 17,18 which are interconnected by an upper rectangular wall 19, a lower rectangular wall 20, and two rectangular side walls 21. An abutment 23 is defined on the upper rectangular face 19 a small distance up from the first end 17 of the arm 16. The abutment 23 extends right across the upper face 19, parallel to the rectangular ends 17,18. The first end 17 is pivotally mounted on the first face 4 of the casing 2 for pivotal movement about an axis 22 parallel to the first and second pins 8,9. The axis 22 is adjacent the step 6 between the first and second faces 4 and 5 of the casing 2.

A third pin 24 is mounted on the second end 18 of the arm 16 such that the third pin 24 extends from the arm 16 in a direction substantially parallel to the axis 22 and parallel to the first and second pins 8,9. The arm 16 is made from an electrically insulating material.

The third pin 24 is made from an electrically conductive material and is secured to the arm 16 in any suitable manner. The third pin 24 forms part of the plug circuit contained within the plug 1. This can be achieved by connecting the third pin 24 to a wire which extends through the arm and out of the arm through an aperture in end 17 of the arm 16. The wire (not shown) can then be inserted through another aperture in the casing 2 so as to be connected to the plug circuit

contained within the casing 2. It is envisaged that the third pin 24 comprises the earth pin of the plug circuit.

The arm 16 and the third pin 24 can thus pivot, about axis 22, from a substantially horizontal position in which the arm 16 and pin 24 are substantially parallel with the base 3 of the casing 2 (as shown in Figure 1) to a substantially vertical position in which the arm 16 and pin 24 are substantially perpendicular to the base 3 of the casing 2 (as shown in Figure 3).

In the folded condition of the plug, the arm 16 is in the substantially horizontal

position with the lower wall 20 of the arm 16 adjacent the first face 4 of the casing 2. In this position of arm 16, the cover 14 can be opened, as shown in Figure 1, to enable the fuse 11 to be changed if necessary. When the arm 16 is in the substantially horizontal position shown in Figure 1, the third pin 24 is adjacent the first pin 8 extending from the casing 2 and thus the plug is substantially flat and occupies relatively little space. The pins 8,9 and 24 of the plug 1 cannot be inserted into a standard three aperture UK plug socket because the third pin 24 is not aligned with the third aperture of the socket. Thus, in this condition, the fuse 11 can be safely changed by a person without the person accidentally receiving an electric shock.

After the fuse 11 has been changed and a new fuse 11 has been secured in the cavity 10 of the casing 2, the cover 14 is lowered so that the cover 14 closes the cavity 10. With the cover 14 in the closed position, the tab 15 on the cover 14 extends into the cavity 10 and completes the plug circuit between the second end 13 of the fuse 11 and the adjacent electrical contact.

The arm 16 is then raised from the substantially horizontal position to the substantially vertical position about the axis 22. The abutment 23, which extends across the upper wall 19 of the arm 16 comprises retaining means which

extends over part of the lip 6, part of the second face 5 of the casing 2 and part of the cover 14 so that the cover 14 of the cavity 10 cannot be opened.

The pins 8, 9 and 24 of the plug 1 are now in a position in which they can be aligned with the three apertures of an electric wall socket. The pins 8,9 and 24 can then be inserted into the wall socket so that electricity flows from the socket into the plug 1. The plug 1 is provided with a cable (not shown) which extends from the plug 1 to interconnect the plug circuit and an electrical appliance such as a laptop computer or a video camera and thus electricity is provided for the appliance.

It will be appreciated that, when the pins 8,9 and 24 of the plug 1 are inserted into the electrical socket, the arm 16 must be in the substantially vertical position so that the third pin 24 is aligned with the third aperture of the socket. When the arm 16 is in this substantially vertical position, the abutment 23 extends over part of the cover 14, thus preventing the cover 14 from being opened when the plug 1 is inserted into the socket. Thus, the risk of electrocution that could occur by opening the cover 14 and changing the fuse 11 when the plug 1 is in the socket is reduced because the cover 14 cannot be opened until the plug 1 is removed from the wall socket and the arm 16 is lowered to the substantially horizontal position.

It is also to be appreciated that, even if the cover 14 is open, the arm 16 is raised to the substantially vertical position and the plug 1 is inserted into the wall socket, there is still a reduced risk of electric shock because, when the cover 14 is open, the electrically conductive tab 15 of the cover 14 is not located between the second end 13 of the fuse 11 and the adjacent electrical contact in the plug 1 and thus the plug circuit is not complete.

Thus the risk of electrocution firstly is reduced by preventing the fuse cover 14 from being opened when the plug 1 is inserted in the wall socket and secondly

by breaking the plug circuit if the plug is inserted in the wall socket with the fuse cover 14 open.

Referring now to Figure 4, an alternative embodiment of the electrical plug 1 is shown with like features being numbered with like numerals.

The plug I comprises a casing 2 of generally flat, box shape. The features of the casing 2 are similar to those described above except that, in this embodiment, the elongate cavity 10 extends between two opposed side walls 7 of the casing 2, substantially perpendicularly to the parallel pins 8 and 9. Thus, the distance by which the casing 2 extends behind the parallel pins 8,9 is reduced and the plug 1 occupies less space.

The plug I further comprises a closure comprising a fuse cover 14 as has been previously described. However, in this embodiment, the cover 14 is pivotally mounted at one end of the casing remote from the pins 8 and 9 and is pivotable about an axis parallel to the cavity 10 and perpendicular to the parallel pins 8 and 9 and to the axis 22 about which the arm 16 is pivotally movable.

In this embodiment a flash cover 25 is provided in the form of a plate having a lower half 26 and an upper half 27, the upper half 27 being pivotally movable relative to the lower half 26 about an axis 28.

The lower half 26 is substantially rectangular and has two spaced apart rectangular apertures. The lower half 26 is mounted on and is parallel to the side wall 7 of the casing 2 from which the pins 8 and 9 project. When so mounted, the pins 8,9 project through the apertures of the lower half 26 of the flash plate 25.

The upper half 27 is substantially semicircular and has a lower, substantially straight edge which is pivotally mounted on the lower half 26. A rectangular

slot 29 is defined on part of the upper half 27 remote from the axis 28. The slot 29 is dimensioned such that the third pin 24 can extend through said slot 29 as will be further described hereinafter.

The flash plate 15 is made from an electrically insulating material. The shape of the plate is such that there is a predetermined area of the flash plate 25 which surrounds each pin 8,9 and 24. This predetermined area is dimensioned to conform to appropriate safety standards such as British Safety standards. The flash plate 25 can be any shape provided the chosen shape provides the predetermined area necessary to surround each pin and conform to the appropriate standards.

In the folded condition of the plug 1, the arm 16 is in the substantially horizontal position with the lower wall 20 of the arm adjacent the first face 4 of the casing 2. In this position of arm 16, the cover 14 can be opened, as shown in Figure 4, to enable the fuse to be changed if necessary. The upper half 27 of the flash plate 25 is folded to an inoperative position in which the upper half 27 extends substantially perpendicularly from the lower half 26 of the flash plate in a direction parallel to the pins 8,9.

Thus, the cover 14 is mounted for pivotal movement about an axis perpendicular to the axis 22 about which the arm 16 can pivot. Thus, with the cover 14 open, the arm 16 cannot be raised to the substantially vertical, operative position because a side edge of the cover 14 abuts against end 17 of arm 16. When the cover 14 is open, the arm 16 cannot be raised to an operative position in which the pins 8, 9 and 24 of the plug 1 can be inserted into a three aperture wall socket and the risk of electrocution is therefore reduced.

After the fuse 11 has been changed, the cover 14 is lowered so that the cover 14 closes the cavity 10 and the tab 15 on the cover 14 extends into the cavity 10 and completes the plug circuit as has been previously described. The arm 16 can

then be raised to the substantially vertical, operative position as shown in Figure 5. The abutment 23 of the arm 16 extends over part of the cover 14 and thus retains the cover 14 in the closed position. The upper half 27 of the flash plate 25 can then be raised from the horizontal, inoperative position to a vertical, operative position. When so raised the third pin 24 projects through the slot 29 on the upper half 27 and the pins 8, 9 project through the apertures in the lower half 26 of the flash plate 25. This is shown in Figure 6.

With arm 16 in the vertical, operative position and the upper half 27 of the flash plate 25 in the vertical, operative position, the engagement of the slot 29 with the third pin 24 prevents the pin 24 from being lowered to the inoperative position. The pins 8, 9 and 24 can then be inserted into a wall socket.

Thus the risk of electrocution is further reduced by the cover 14, when open,

preventing the arm 16 and third pin 24 from being raised to the operative position in which the pins 8, 9 and 24 can be inserted into a wall socket. When the arm 16 and third pin 24 are in the operative position, the upper half 26 of flash cover 25 locks the arm in position and also makes it more difficult for a : person holding the plug 1 itself to touch the pins 8,9 and 24 and risk electrocution.

It will be appreciated that the pin 24 and the arm 16 may be made from an electrically conductive material, or that the arm and the pin may both be made from a non-electrically conductive material.

It will further be appreciated that in a modified embodiment the cover 14 need not necessarily be provided with the tab 15, and that the plug circuit is completed by insertion of a fuse into a modified cavity.

Claims

CLAIMS 1. An electrical plug where at least one of the connecting pins (numbered 24 on figures 4,5 and 6) is moveable on an arm (numbered 16 on figures 4,5 and 6) about an axis parallel to the pins (numbered 8 or 9 on figures 4,5 and 6.
2. A plug as claimed in Claim 1 where the upper part of the vertical flash plate (numbered 27 on figures 4,5 and 6) which is recessed to substantially accommodate and fix the moveable arm can be folded through 90 degrees to become parallel to the horizontal pins.
3. A plug as claimed in Claim 1 or Claim 2 and where a cavity is provided in the body of the plug to receive a fuse (numbered 11 on figure 4) and a closure (numbered 14 on figures 4,5 and 6) is provided which must be closed to permit the moveable arm (numbered 16 on figures 4,5 and 6) or the vertical flash plate (numbered 27 on figures 4,5 and 6) to assume an operative condition which would permit the plug to then be inserted into an electrical socket.